draft-lafon-rfc2616bis-01.txt   draft-lafon-rfc2616bis-02.txt 
Network Working Group R. Fielding Network Working Group R. Fielding
Internet-Draft Day Software Internet-Draft Day Software
Obsoletes: 2616 (if approved) J. Gettys Obsoletes: 2616 (if approved) J. Gettys
Intended status: Standards Track J. Mogul Intended status: Standards Track J. Mogul
Expires: April 25, 2007 HP Expires: May 23, 2007 HP
H. Frystyk H. Frystyk
Microsoft Microsoft
L. Masinter L. Masinter
Adobe Systems Adobe Systems
P. Leach P. Leach
Microsoft Microsoft
T. Berners-Lee T. Berners-Lee
W3C/MIT W3C/MIT
Y. Lafon, Ed. Y. Lafon, Ed.
W3C W3C
J. Reschke, Ed. J. Reschke, Ed.
greenbytes greenbytes
October 22, 2006 November 19, 2006
Hypertext Transfer Protocol -- HTTP/1.1 Hypertext Transfer Protocol -- HTTP/1.1
draft-lafon-rfc2616bis-01 draft-lafon-rfc2616bis-02
Status of this Memo Status of this Memo
By submitting this Internet-Draft, each author represents that any By submitting this Internet-Draft, each author represents that any
applicable patent or other IPR claims of which he or she is aware applicable patent or other IPR claims of which he or she is aware
have been or will be disclosed, and any of which he or she becomes have been or will be disclosed, and any of which he or she becomes
aware will be disclosed, in accordance with Section 6 of BCP 79. aware will be disclosed, in accordance with Section 6 of BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that Task Force (IETF), its areas, and its working groups. Note that
skipping to change at page 1, line 48 skipping to change at page 1, line 48
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt. http://www.ietf.org/ietf/1id-abstracts.txt.
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This Internet-Draft will expire on April 25, 2007. This Internet-Draft will expire on May 23, 2007.
Abstract Abstract
The Hypertext Transfer Protocol (HTTP) is an application-level The Hypertext Transfer Protocol (HTTP) is an application-level
protocol for distributed, collaborative, hypermedia information protocol for distributed, collaborative, hypermedia information
systems. It is a generic, stateless, protocol which can be used for systems. It is a generic, stateless, protocol which can be used for
many tasks beyond its use for hypertext, such as name servers and many tasks beyond its use for hypertext, such as name servers and
distributed object management systems, through extension of its distributed object management systems, through extension of its
request methods, error codes and headers [47]. A feature of HTTP is request methods, error codes and headers [RFC2324]. A feature of
the typing and negotiation of data representation, allowing systems HTTP is the typing and negotiation of data representation, allowing
to be built independently of the data being transferred. systems to be built independently of the data being transferred.
HTTP has been in use by the World-Wide Web global information HTTP has been in use by the World-Wide Web global information
initiative since 1990. This specification defines the protocol initiative since 1990. This specification defines the protocol
referred to as "HTTP/1.1", and is an update to RFC2616. referred to as "HTTP/1.1", and is an update to RFC2616.
Editorial Note (To be removed by RFC Editor before publication) Editorial Note (To be removed by RFC Editor before publication)
Distribution of this document is unlimited. Please send comments to Distribution of this document is unlimited. Please send comments to
the Hypertext Transfer Protocol (HTTP) mailing list at the Hypertext Transfer Protocol (HTTP) mailing list at
ietf-http-wg@w3.org [51], which may be joined by sending a message ietf-http-wg@w3.org [1], which may be joined by sending a message
with subject "subscribe" to ietf-http-wg-request@w3.org [52]. with subject "subscribe" to ietf-http-wg-request@w3.org [2].
Discussions of the HTTP working group are archived at Discussions of the HTTP working group are archived at
<http://lists.w3.org/Archives/Public/ietf-http-wg/>. XML versions, <http://lists.w3.org/Archives/Public/ietf-http-wg/>. XML versions,
latest edits and the issues list for this document are available from latest edits and the issues list for this document are available from
<http://www.w3.org/Protocols/HTTP/1.1/>. <http://www.w3.org/Protocols/HTTP/1.1/rfc2616bis/>.
The purpose of this document is to revise RFC2616 ([50]), doing only The purpose of this document is to revise [RFC2616], doing only
minimal corrections. For now, it is not planned to advance the minimal corrections. For now, it is not planned to advance the
standards level of HTTP, thus - if published - the specification will standards level of HTTP, thus - if published - the specification will
still be a "Proposed Standard" (see [46]). still be a "Proposed Standard" (see [RFC2026]).
The current plan is to incorporate known errata, and to update the The current plan is to incorporate known errata, and to update the
specification text according to the current IETF publication specification text according to the current IETF publication
guidelines. In particular: guidelines. In particular:
o Incorporate the corrections collected in the RFC2616 errata o Incorporate the corrections collected in the RFC2616 errata
document (<http://purl.org/NET/http-errata>) (most of the document (<http://purl.org/NET/http-errata>) (most of the
suggested fixes have been applied to draft 01). suggested fixes have been applied to draft 01).
o Incorporate corrections for newly discovered and agreed-upon o Incorporate corrections for newly discovered and agreed-upon
problems, using the HTTP WG mailing list as forum. problems, using the HTTP WG mailing list as forum and
<http://www.w3.org/Protocols/HTTP/1.1/rfc2616bis/issues/> as
issues list.
o Update references, and re-classify them into "Normative" and o Update references, and re-classify them into "Normative" and
"Informative", based on the prior work done by Jim Gettys in "Informative", based on the prior work done by Jim Gettys in
<http://tools.ietf.org/html/draft-gettys-http-v11-spec-rev-00>. <http://tools.ietf.org/html/draft-gettys-http-v11-spec-rev-00>.
This document is based on a variant of the original RFC2616 This document is based on a variant of the original RFC2616
specification formatted using Marshall T. Rose's "xml2rfc" tool (see specification formatted using Marshall T. Rose's "xml2rfc" tool (see
<http://xml.resource.org>) and therefore deviates from the original <http://xml.resource.org>) and therefore deviates from the original
text in word wrapping, page breaks, list formatting, reference text in word wrapping, page breaks, list formatting, reference
formatting, whitespace usage and appendix numbering. Otherwise, it formatting, whitespace usage and appendix numbering. Otherwise, it
is supposed to contain an accurate copy of the original specification is supposed to contain an accurate copy of the original specification
text. See <http://www.w3.org/Protocols/HTTP/1.1/ text. See <http://www.w3.org/Protocols/HTTP/1.1/
rfc2616bis-00-from-rfc2616.diff.html> for a comparison between both rfc2616bis-00-from-rfc2616.diff.html> for a comparison between both
documents, as generated by "rfcdiff" documents, as generated by "rfcdiff"
(<http://tools.ietf.org/tools/rfcdiff/>). (<http://tools.ietf.org/tools/rfcdiff/>).
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 11 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 10
1.1. Purpose . . . . . . . . . . . . . . . . . . . . . . . . 11 1.1. Purpose . . . . . . . . . . . . . . . . . . . . . . . . 10
1.2. Requirements . . . . . . . . . . . . . . . . . . . . . . 11 1.2. Requirements . . . . . . . . . . . . . . . . . . . . . . 10
1.3. Terminology . . . . . . . . . . . . . . . . . . . . . . 12 1.3. Terminology . . . . . . . . . . . . . . . . . . . . . . 11
1.4. Overall Operation . . . . . . . . . . . . . . . . . . . 16 1.4. Overall Operation . . . . . . . . . . . . . . . . . . . 15
2. Notational Conventions and Generic Grammar . . . . . . . . . 19 2. Notational Conventions and Generic Grammar . . . . . . . . . 18
2.1. Augmented BNF . . . . . . . . . . . . . . . . . . . . . 19 2.1. Augmented BNF . . . . . . . . . . . . . . . . . . . . . 18
2.2. Basic Rules . . . . . . . . . . . . . . . . . . . . . . 21 2.2. Basic Rules . . . . . . . . . . . . . . . . . . . . . . 20
3. Protocol Parameters . . . . . . . . . . . . . . . . . . . . . 23 3. Protocol Parameters . . . . . . . . . . . . . . . . . . . . . 22
3.1. HTTP Version . . . . . . . . . . . . . . . . . . . . . . 23 3.1. HTTP Version . . . . . . . . . . . . . . . . . . . . . . 22
3.2. Uniform Resource Identifiers . . . . . . . . . . . . . . 24 3.2. Uniform Resource Identifiers . . . . . . . . . . . . . . 23
3.2.1. General Syntax . . . . . . . . . . . . . . . . . . . 24 3.2.1. General Syntax . . . . . . . . . . . . . . . . . . . 23
3.2.2. http URL . . . . . . . . . . . . . . . . . . . . . . 25 3.2.2. http URL . . . . . . . . . . . . . . . . . . . . . . 24
3.2.3. URI Comparison . . . . . . . . . . . . . . . . . . . 25 3.2.3. URI Comparison . . . . . . . . . . . . . . . . . . . 24
3.3. Date/Time Formats . . . . . . . . . . . . . . . . . . . 26 3.3. Date/Time Formats . . . . . . . . . . . . . . . . . . . 25
3.3.1. Full Date . . . . . . . . . . . . . . . . . . . . . 26 3.3.1. Full Date . . . . . . . . . . . . . . . . . . . . . 25
3.3.2. Delta Seconds . . . . . . . . . . . . . . . . . . . 27 3.3.2. Delta Seconds . . . . . . . . . . . . . . . . . . . 26
3.4. Character Sets . . . . . . . . . . . . . . . . . . . . . 27 3.4. Character Sets . . . . . . . . . . . . . . . . . . . . . 26
3.4.1. Missing Charset . . . . . . . . . . . . . . . . . . 28 3.4.1. Missing Charset . . . . . . . . . . . . . . . . . . 27
3.5. Content Codings . . . . . . . . . . . . . . . . . . . . 29 3.5. Content Codings . . . . . . . . . . . . . . . . . . . . 28
3.6. Transfer Codings . . . . . . . . . . . . . . . . . . . . 30 3.6. Transfer Codings . . . . . . . . . . . . . . . . . . . . 29
3.6.1. Chunked Transfer Coding . . . . . . . . . . . . . . 31 3.6.1. Chunked Transfer Coding . . . . . . . . . . . . . . 30
3.7. Media Types . . . . . . . . . . . . . . . . . . . . . . 32 3.7. Media Types . . . . . . . . . . . . . . . . . . . . . . 31
3.7.1. Canonicalization and Text Defaults . . . . . . . . . 33 3.7.1. Canonicalization and Text Defaults . . . . . . . . . 32
3.7.2. Multipart Types . . . . . . . . . . . . . . . . . . 34 3.7.2. Multipart Types . . . . . . . . . . . . . . . . . . 33
3.8. Product Tokens . . . . . . . . . . . . . . . . . . . . . 34 3.8. Product Tokens . . . . . . . . . . . . . . . . . . . . . 33
3.9. Quality Values . . . . . . . . . . . . . . . . . . . . . 35 3.9. Quality Values . . . . . . . . . . . . . . . . . . . . . 34
3.10. Language Tags . . . . . . . . . . . . . . . . . . . . . 35 3.10. Language Tags . . . . . . . . . . . . . . . . . . . . . 34
3.11. Entity Tags . . . . . . . . . . . . . . . . . . . . . . 36 3.11. Entity Tags . . . . . . . . . . . . . . . . . . . . . . 35
3.12. Range Units . . . . . . . . . . . . . . . . . . . . . . 36 3.12. Range Units . . . . . . . . . . . . . . . . . . . . . . 35
4. HTTP Message . . . . . . . . . . . . . . . . . . . . . . . . 38 4. HTTP Message . . . . . . . . . . . . . . . . . . . . . . . . 37
4.1. Message Types . . . . . . . . . . . . . . . . . . . . . 38 4.1. Message Types . . . . . . . . . . . . . . . . . . . . . 37
4.2. Message Headers . . . . . . . . . . . . . . . . . . . . 38 4.2. Message Headers . . . . . . . . . . . . . . . . . . . . 37
4.3. Message Body . . . . . . . . . . . . . . . . . . . . . . 39 4.3. Message Body . . . . . . . . . . . . . . . . . . . . . . 38
4.4. Message Length . . . . . . . . . . . . . . . . . . . . . 40 4.4. Message Length . . . . . . . . . . . . . . . . . . . . . 39
4.5. General Header Fields . . . . . . . . . . . . . . . . . 41 4.5. General Header Fields . . . . . . . . . . . . . . . . . 40
5. Request . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 5. Request . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
5.1. Request-Line . . . . . . . . . . . . . . . . . . . . . . 43 5.1. Request-Line . . . . . . . . . . . . . . . . . . . . . . 42
5.1.1. Method . . . . . . . . . . . . . . . . . . . . . . . 43 5.1.1. Method . . . . . . . . . . . . . . . . . . . . . . . 42
5.1.2. Request-URI . . . . . . . . . . . . . . . . . . . . 44 5.1.2. Request-URI . . . . . . . . . . . . . . . . . . . . 43
5.2. The Resource Identified by a Request . . . . . . . . . . 45 5.2. The Resource Identified by a Request . . . . . . . . . . 44
5.3. Request Header Fields . . . . . . . . . . . . . . . . . 46 5.3. Request Header Fields . . . . . . . . . . . . . . . . . 45
6. Response . . . . . . . . . . . . . . . . . . . . . . . . . . 47 6. Response . . . . . . . . . . . . . . . . . . . . . . . . . . 46
6.1. Status-Line . . . . . . . . . . . . . . . . . . . . . . 47 6.1. Status-Line . . . . . . . . . . . . . . . . . . . . . . 46
6.1.1. Status Code and Reason Phrase . . . . . . . . . . . 47 6.1.1. Status Code and Reason Phrase . . . . . . . . . . . 46
6.2. Response Header Fields . . . . . . . . . . . . . . . . . 50 6.2. Response Header Fields . . . . . . . . . . . . . . . . . 49
7. Entity . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 7. Entity . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
7.1. Entity Header Fields . . . . . . . . . . . . . . . . . . 51 7.1. Entity Header Fields . . . . . . . . . . . . . . . . . . 50
7.2. Entity Body . . . . . . . . . . . . . . . . . . . . . . 51 7.2. Entity Body . . . . . . . . . . . . . . . . . . . . . . 50
7.2.1. Type . . . . . . . . . . . . . . . . . . . . . . . . 52 7.2.1. Type . . . . . . . . . . . . . . . . . . . . . . . . 51
7.2.2. Entity Length . . . . . . . . . . . . . . . . . . . 52 7.2.2. Entity Length . . . . . . . . . . . . . . . . . . . 51
8. Connections . . . . . . . . . . . . . . . . . . . . . . . . . 53 8. Connections . . . . . . . . . . . . . . . . . . . . . . . . . 52
8.1. Persistent Connections . . . . . . . . . . . . . . . . . 53 8.1. Persistent Connections . . . . . . . . . . . . . . . . . 52
8.1.1. Purpose . . . . . . . . . . . . . . . . . . . . . . 53 8.1.1. Purpose . . . . . . . . . . . . . . . . . . . . . . 52
8.1.2. Overall Operation . . . . . . . . . . . . . . . . . 53 8.1.2. Overall Operation . . . . . . . . . . . . . . . . . 52
8.1.3. Proxy Servers . . . . . . . . . . . . . . . . . . . 55 8.1.3. Proxy Servers . . . . . . . . . . . . . . . . . . . 54
8.1.4. Practical Considerations . . . . . . . . . . . . . . 55 8.1.4. Practical Considerations . . . . . . . . . . . . . . 54
8.2. Message Transmission Requirements . . . . . . . . . . . 56 8.2. Message Transmission Requirements . . . . . . . . . . . 55
8.2.1. Persistent Connections and Flow Control . . . . . . 56 8.2.1. Persistent Connections and Flow Control . . . . . . 55
8.2.2. Monitoring Connections for Error Status Messages . . 56 8.2.2. Monitoring Connections for Error Status Messages . . 55
8.2.3. Use of the 100 (Continue) Status . . . . . . . . . . 57 8.2.3. Use of the 100 (Continue) Status . . . . . . . . . . 56
8.2.4. Client Behavior if Server Prematurely Closes 8.2.4. Client Behavior if Server Prematurely Closes
Connection . . . . . . . . . . . . . . . . . . . . . 59 Connection . . . . . . . . . . . . . . . . . . . . . 58
9. Method Definitions . . . . . . . . . . . . . . . . . . . . . 60 9. Method Definitions . . . . . . . . . . . . . . . . . . . . . 59
9.1. Safe and Idempotent Methods . . . . . . . . . . . . . . 60 9.1. Safe and Idempotent Methods . . . . . . . . . . . . . . 59
9.1.1. Safe Methods . . . . . . . . . . . . . . . . . . . . 60 9.1.1. Safe Methods . . . . . . . . . . . . . . . . . . . . 59
9.1.2. Idempotent Methods . . . . . . . . . . . . . . . . . 60 9.1.2. Idempotent Methods . . . . . . . . . . . . . . . . . 59
9.2. OPTIONS . . . . . . . . . . . . . . . . . . . . . . . . 61 9.2. OPTIONS . . . . . . . . . . . . . . . . . . . . . . . . 60
9.3. GET . . . . . . . . . . . . . . . . . . . . . . . . . . 62 9.3. GET . . . . . . . . . . . . . . . . . . . . . . . . . . 61
9.4. HEAD . . . . . . . . . . . . . . . . . . . . . . . . . . 62 9.4. HEAD . . . . . . . . . . . . . . . . . . . . . . . . . . 61
9.5. POST . . . . . . . . . . . . . . . . . . . . . . . . . . 63 9.5. POST . . . . . . . . . . . . . . . . . . . . . . . . . . 62
9.6. PUT . . . . . . . . . . . . . . . . . . . . . . . . . . 64 9.6. PUT . . . . . . . . . . . . . . . . . . . . . . . . . . 63
9.7. DELETE . . . . . . . . . . . . . . . . . . . . . . . . . 65 9.7. DELETE . . . . . . . . . . . . . . . . . . . . . . . . . 64
9.8. TRACE . . . . . . . . . . . . . . . . . . . . . . . . . 65 9.8. TRACE . . . . . . . . . . . . . . . . . . . . . . . . . 64
9.9. CONNECT . . . . . . . . . . . . . . . . . . . . . . . . 66 9.9. CONNECT . . . . . . . . . . . . . . . . . . . . . . . . 65
10. Status Code Definitions . . . . . . . . . . . . . . . . . . . 67 10. Status Code Definitions . . . . . . . . . . . . . . . . . . . 66
10.1. Informational 1xx . . . . . . . . . . . . . . . . . . . 67 10.1. Informational 1xx . . . . . . . . . . . . . . . . . . . 66
10.1.1. 100 Continue . . . . . . . . . . . . . . . . . . . . 67 10.1.1. 100 Continue . . . . . . . . . . . . . . . . . . . . 66
10.1.2. 101 Switching Protocols . . . . . . . . . . . . . . 67 10.1.2. 101 Switching Protocols . . . . . . . . . . . . . . 66
10.2. Successful 2xx . . . . . . . . . . . . . . . . . . . . . 68 10.2. Successful 2xx . . . . . . . . . . . . . . . . . . . . . 67
10.2.1. 200 OK . . . . . . . . . . . . . . . . . . . . . . . 68 10.2.1. 200 OK . . . . . . . . . . . . . . . . . . . . . . . 67
10.2.2. 201 Created . . . . . . . . . . . . . . . . . . . . 68 10.2.2. 201 Created . . . . . . . . . . . . . . . . . . . . 67
10.2.3. 202 Accepted . . . . . . . . . . . . . . . . . . . . 68 10.2.3. 202 Accepted . . . . . . . . . . . . . . . . . . . . 67
10.2.4. 203 Non-Authoritative Information . . . . . . . . . 69 10.2.4. 203 Non-Authoritative Information . . . . . . . . . 68
10.2.5. 204 No Content . . . . . . . . . . . . . . . . . . . 69 10.2.5. 204 No Content . . . . . . . . . . . . . . . . . . . 68
10.2.6. 205 Reset Content . . . . . . . . . . . . . . . . . 69 10.2.6. 205 Reset Content . . . . . . . . . . . . . . . . . 68
10.2.7. 206 Partial Content . . . . . . . . . . . . . . . . 70 10.2.7. 206 Partial Content . . . . . . . . . . . . . . . . 69
10.3. Redirection 3xx . . . . . . . . . . . . . . . . . . . . 70 10.3. Redirection 3xx . . . . . . . . . . . . . . . . . . . . 69
10.3.1. 300 Multiple Choices . . . . . . . . . . . . . . . . 71 10.3.1. 300 Multiple Choices . . . . . . . . . . . . . . . . 70
10.3.2. 301 Moved Permanently . . . . . . . . . . . . . . . 71 10.3.2. 301 Moved Permanently . . . . . . . . . . . . . . . 70
10.3.3. 302 Found . . . . . . . . . . . . . . . . . . . . . 72 10.3.3. 302 Found . . . . . . . . . . . . . . . . . . . . . 71
10.3.4. 303 See Other . . . . . . . . . . . . . . . . . . . 72 10.3.4. 303 See Other . . . . . . . . . . . . . . . . . . . 71
10.3.5. 304 Not Modified . . . . . . . . . . . . . . . . . . 73 10.3.5. 304 Not Modified . . . . . . . . . . . . . . . . . . 72
10.3.6. 305 Use Proxy . . . . . . . . . . . . . . . . . . . 73 10.3.6. 305 Use Proxy . . . . . . . . . . . . . . . . . . . 72
10.3.7. 306 (Unused) . . . . . . . . . . . . . . . . . . . . 74 10.3.7. 306 (Unused) . . . . . . . . . . . . . . . . . . . . 73
10.3.8. 307 Temporary Redirect . . . . . . . . . . . . . . . 74 10.3.8. 307 Temporary Redirect . . . . . . . . . . . . . . . 73
10.4. Client Error 4xx . . . . . . . . . . . . . . . . . . . . 74 10.4. Client Error 4xx . . . . . . . . . . . . . . . . . . . . 73
10.4.1. 400 Bad Request . . . . . . . . . . . . . . . . . . 75 10.4.1. 400 Bad Request . . . . . . . . . . . . . . . . . . 74
10.4.2. 401 Unauthorized . . . . . . . . . . . . . . . . . . 75 10.4.2. 401 Unauthorized . . . . . . . . . . . . . . . . . . 74
10.4.3. 402 Payment Required . . . . . . . . . . . . . . . . 75 10.4.3. 402 Payment Required . . . . . . . . . . . . . . . . 74
10.4.4. 403 Forbidden . . . . . . . . . . . . . . . . . . . 75 10.4.4. 403 Forbidden . . . . . . . . . . . . . . . . . . . 74
10.4.5. 404 Not Found . . . . . . . . . . . . . . . . . . . 75 10.4.5. 404 Not Found . . . . . . . . . . . . . . . . . . . 74
10.4.6. 405 Method Not Allowed . . . . . . . . . . . . . . . 76 10.4.6. 405 Method Not Allowed . . . . . . . . . . . . . . . 75
10.4.7. 406 Not Acceptable . . . . . . . . . . . . . . . . . 76 10.4.7. 406 Not Acceptable . . . . . . . . . . . . . . . . . 75
10.4.8. 407 Proxy Authentication Required . . . . . . . . . 76 10.4.8. 407 Proxy Authentication Required . . . . . . . . . 75
10.4.9. 408 Request Timeout . . . . . . . . . . . . . . . . 77 10.4.9. 408 Request Timeout . . . . . . . . . . . . . . . . 76
10.4.10. 409 Conflict . . . . . . . . . . . . . . . . . . . . 77 10.4.10. 409 Conflict . . . . . . . . . . . . . . . . . . . . 76
10.4.11. 410 Gone . . . . . . . . . . . . . . . . . . . . . . 77 10.4.11. 410 Gone . . . . . . . . . . . . . . . . . . . . . . 76
10.4.12. 411 Length Required . . . . . . . . . . . . . . . . 78 10.4.12. 411 Length Required . . . . . . . . . . . . . . . . 77
10.4.13. 412 Precondition Failed . . . . . . . . . . . . . . 78 10.4.13. 412 Precondition Failed . . . . . . . . . . . . . . 77
10.4.14. 413 Request Entity Too Large . . . . . . . . . . . . 78 10.4.14. 413 Request Entity Too Large . . . . . . . . . . . . 77
10.4.15. 414 Request-URI Too Long . . . . . . . . . . . . . . 78 10.4.15. 414 Request-URI Too Long . . . . . . . . . . . . . . 77
10.4.16. 415 Unsupported Media Type . . . . . . . . . . . . . 78 10.4.16. 415 Unsupported Media Type . . . . . . . . . . . . . 77
10.4.17. 416 Requested Range Not Satisfiable . . . . . . . . 78 10.4.17. 416 Requested Range Not Satisfiable . . . . . . . . 77
10.4.18. 417 Expectation Failed . . . . . . . . . . . . . . . 79 10.4.18. 417 Expectation Failed . . . . . . . . . . . . . . . 78
10.5. Server Error 5xx . . . . . . . . . . . . . . . . . . . . 79 10.5. Server Error 5xx . . . . . . . . . . . . . . . . . . . . 78
10.5.1. 500 Internal Server Error . . . . . . . . . . . . . 79 10.5.1. 500 Internal Server Error . . . . . . . . . . . . . 78
10.5.2. 501 Not Implemented . . . . . . . . . . . . . . . . 79 10.5.2. 501 Not Implemented . . . . . . . . . . . . . . . . 78
10.5.3. 502 Bad Gateway . . . . . . . . . . . . . . . . . . 79 10.5.3. 502 Bad Gateway . . . . . . . . . . . . . . . . . . 78
10.5.4. 503 Service Unavailable . . . . . . . . . . . . . . 80 10.5.4. 503 Service Unavailable . . . . . . . . . . . . . . 79
10.5.5. 504 Gateway Timeout . . . . . . . . . . . . . . . . 80 10.5.5. 504 Gateway Timeout . . . . . . . . . . . . . . . . 79
10.5.6. 505 HTTP Version Not Supported . . . . . . . . . . . 80 10.5.6. 505 HTTP Version Not Supported . . . . . . . . . . . 79
11. Access Authentication . . . . . . . . . . . . . . . . . . . . 81 11. Access Authentication . . . . . . . . . . . . . . . . . . . . 80
12. Content Negotiation . . . . . . . . . . . . . . . . . . . . . 82 12. Content Negotiation . . . . . . . . . . . . . . . . . . . . . 81
12.1. Server-driven Negotiation . . . . . . . . . . . . . . . 82 12.1. Server-driven Negotiation . . . . . . . . . . . . . . . 81
12.2. Agent-driven Negotiation . . . . . . . . . . . . . . . . 83 12.2. Agent-driven Negotiation . . . . . . . . . . . . . . . . 82
12.3. Transparent Negotiation . . . . . . . . . . . . . . . . 84 12.3. Transparent Negotiation . . . . . . . . . . . . . . . . 83
13. Caching in HTTP . . . . . . . . . . . . . . . . . . . . . . . 85 13. Caching in HTTP . . . . . . . . . . . . . . . . . . . . . . . 84
13.1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86 13.1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
13.1.1. Cache Correctness . . . . . . . . . . . . . . . . . 86 13.1.1. Cache Correctness . . . . . . . . . . . . . . . . . 85
13.1.2. Warnings . . . . . . . . . . . . . . . . . . . . . . 87 13.1.2. Warnings . . . . . . . . . . . . . . . . . . . . . . 86
13.1.3. Cache-control Mechanisms . . . . . . . . . . . . . . 88 13.1.3. Cache-control Mechanisms . . . . . . . . . . . . . . 87
13.1.4. Explicit User Agent Warnings . . . . . . . . . . . . 88 13.1.4. Explicit User Agent Warnings . . . . . . . . . . . . 87
13.1.5. Exceptions to the Rules and Warnings . . . . . . . . 89 13.1.5. Exceptions to the Rules and Warnings . . . . . . . . 88
13.1.6. Client-controlled Behavior . . . . . . . . . . . . . 89 13.1.6. Client-controlled Behavior . . . . . . . . . . . . . 88
13.2. Expiration Model . . . . . . . . . . . . . . . . . . . . 90 13.2. Expiration Model . . . . . . . . . . . . . . . . . . . . 89
13.2.1. Server-Specified Expiration . . . . . . . . . . . . 90 13.2.1. Server-Specified Expiration . . . . . . . . . . . . 89
13.2.2. Heuristic Expiration . . . . . . . . . . . . . . . . 90 13.2.2. Heuristic Expiration . . . . . . . . . . . . . . . . 89
13.2.3. Age Calculations . . . . . . . . . . . . . . . . . . 91 13.2.3. Age Calculations . . . . . . . . . . . . . . . . . . 90
13.2.4. Expiration Calculations . . . . . . . . . . . . . . 93 13.2.4. Expiration Calculations . . . . . . . . . . . . . . 92
13.2.5. Disambiguating Expiration Values . . . . . . . . . . 94 13.2.5. Disambiguating Expiration Values . . . . . . . . . . 93
13.2.6. Disambiguating Multiple Responses . . . . . . . . . 95 13.2.6. Disambiguating Multiple Responses . . . . . . . . . 94
13.3. Validation Model . . . . . . . . . . . . . . . . . . . . 95 13.3. Validation Model . . . . . . . . . . . . . . . . . . . . 94
13.3.1. Last-Modified Dates . . . . . . . . . . . . . . . . 96 13.3.1. Last-Modified Dates . . . . . . . . . . . . . . . . 95
13.3.2. Entity Tag Cache Validators . . . . . . . . . . . . 96 13.3.2. Entity Tag Cache Validators . . . . . . . . . . . . 95
13.3.3. Weak and Strong Validators . . . . . . . . . . . . . 97 13.3.3. Weak and Strong Validators . . . . . . . . . . . . . 96
13.3.4. Rules for When to Use Entity Tags and 13.3.4. Rules for When to Use Entity Tags and
Last-Modified Dates . . . . . . . . . . . . . . . . 99 Last-Modified Dates . . . . . . . . . . . . . . . . 98
13.3.5. Non-validating Conditionals . . . . . . . . . . . . 101 13.3.5. Non-validating Conditionals . . . . . . . . . . . . 100
13.4. Response Cacheability . . . . . . . . . . . . . . . . . 101 13.4. Response Cacheability . . . . . . . . . . . . . . . . . 100
13.5. Constructing Responses From Caches . . . . . . . . . . . 102 13.5. Constructing Responses From Caches . . . . . . . . . . . 101
13.5.1. End-to-end and Hop-by-hop Headers . . . . . . . . . 102 13.5.1. End-to-end and Hop-by-hop Headers . . . . . . . . . 101
13.5.2. Non-modifiable Headers . . . . . . . . . . . . . . . 103 13.5.2. Non-modifiable Headers . . . . . . . . . . . . . . . 102
13.5.3. Combining Headers . . . . . . . . . . . . . . . . . 104 13.5.3. Combining Headers . . . . . . . . . . . . . . . . . 103
13.5.4. Combining Byte Ranges . . . . . . . . . . . . . . . 105 13.5.4. Combining Byte Ranges . . . . . . . . . . . . . . . 104
13.6. Caching Negotiated Responses . . . . . . . . . . . . . . 106 13.6. Caching Negotiated Responses . . . . . . . . . . . . . . 105
13.7. Shared and Non-Shared Caches . . . . . . . . . . . . . . 107 13.7. Shared and Non-Shared Caches . . . . . . . . . . . . . . 106
13.8. Errors or Incomplete Response Cache Behavior . . . . . . 107 13.8. Errors or Incomplete Response Cache Behavior . . . . . . 106
13.9. Side Effects of GET and HEAD . . . . . . . . . . . . . . 108 13.9. Side Effects of GET and HEAD . . . . . . . . . . . . . . 107
13.10. Invalidation After Updates or Deletions . . . . . . . . 108 13.10. Invalidation After Updates or Deletions . . . . . . . . 107
13.11. Write-Through Mandatory . . . . . . . . . . . . . . . . 109 13.11. Write-Through Mandatory . . . . . . . . . . . . . . . . 108
13.12. Cache Replacement . . . . . . . . . . . . . . . . . . . 109 13.12. Cache Replacement . . . . . . . . . . . . . . . . . . . 108
13.13. History Lists . . . . . . . . . . . . . . . . . . . . . 110 13.13. History Lists . . . . . . . . . . . . . . . . . . . . . 109
14. Header Field Definitions . . . . . . . . . . . . . . . . . . 111 14. Header Field Definitions . . . . . . . . . . . . . . . . . . 110
14.1. Accept . . . . . . . . . . . . . . . . . . . . . . . . . 111 14.1. Accept . . . . . . . . . . . . . . . . . . . . . . . . . 110
14.2. Accept-Charset . . . . . . . . . . . . . . . . . . . . . 113 14.2. Accept-Charset . . . . . . . . . . . . . . . . . . . . . 112
14.3. Accept-Encoding . . . . . . . . . . . . . . . . . . . . 113 14.3. Accept-Encoding . . . . . . . . . . . . . . . . . . . . 112
14.4. Accept-Language . . . . . . . . . . . . . . . . . . . . 115 14.4. Accept-Language . . . . . . . . . . . . . . . . . . . . 114
14.5. Accept-Ranges . . . . . . . . . . . . . . . . . . . . . 116 14.5. Accept-Ranges . . . . . . . . . . . . . . . . . . . . . 115
14.6. Age . . . . . . . . . . . . . . . . . . . . . . . . . . 116 14.6. Age . . . . . . . . . . . . . . . . . . . . . . . . . . 115
14.7. Allow . . . . . . . . . . . . . . . . . . . . . . . . . 117 14.7. Allow . . . . . . . . . . . . . . . . . . . . . . . . . 116
14.8. Authorization . . . . . . . . . . . . . . . . . . . . . 118 14.8. Authorization . . . . . . . . . . . . . . . . . . . . . 116
14.9. Cache-Control . . . . . . . . . . . . . . . . . . . . . 118 14.9. Cache-Control . . . . . . . . . . . . . . . . . . . . . 117
14.9.1. What is Cacheable . . . . . . . . . . . . . . . . . 120 14.9.1. What is Cacheable . . . . . . . . . . . . . . . . . 119
14.9.2. What May be Stored by Caches . . . . . . . . . . . . 121 14.9.2. What May be Stored by Caches . . . . . . . . . . . . 120
14.9.3. Modifications of the Basic Expiration Mechanism . . 122 14.9.3. Modifications of the Basic Expiration Mechanism . . 121
14.9.4. Cache Revalidation and Reload Controls . . . . . . . 124 14.9.4. Cache Revalidation and Reload Controls . . . . . . . 123
14.9.5. No-Transform Directive . . . . . . . . . . . . . . . 127 14.9.5. No-Transform Directive . . . . . . . . . . . . . . . 125
14.9.6. Cache Control Extensions . . . . . . . . . . . . . . 127 14.9.6. Cache Control Extensions . . . . . . . . . . . . . . 126
14.10. Connection . . . . . . . . . . . . . . . . . . . . . . . 128 14.10. Connection . . . . . . . . . . . . . . . . . . . . . . . 127
14.11. Content-Encoding . . . . . . . . . . . . . . . . . . . . 129 14.11. Content-Encoding . . . . . . . . . . . . . . . . . . . . 128
14.12. Content-Language . . . . . . . . . . . . . . . . . . . . 130 14.12. Content-Language . . . . . . . . . . . . . . . . . . . . 128
14.13. Content-Length . . . . . . . . . . . . . . . . . . . . . 130 14.13. Content-Length . . . . . . . . . . . . . . . . . . . . . 129
14.14. Content-Location . . . . . . . . . . . . . . . . . . . . 131 14.14. Content-Location . . . . . . . . . . . . . . . . . . . . 130
14.15. Content-MD5 . . . . . . . . . . . . . . . . . . . . . . 132 14.15. Content-MD5 . . . . . . . . . . . . . . . . . . . . . . 131
14.16. Content-Range . . . . . . . . . . . . . . . . . . . . . 133 14.16. Content-Range . . . . . . . . . . . . . . . . . . . . . 132
14.17. Content-Type . . . . . . . . . . . . . . . . . . . . . . 135 14.17. Content-Type . . . . . . . . . . . . . . . . . . . . . . 134
14.18. Date . . . . . . . . . . . . . . . . . . . . . . . . . . 136 14.18. Date . . . . . . . . . . . . . . . . . . . . . . . . . . 134
14.18.1. Clockless Origin Server Operation . . . . . . . . . 137 14.18.1. Clockless Origin Server Operation . . . . . . . . . 135
14.19. ETag . . . . . . . . . . . . . . . . . . . . . . . . . . 137 14.19. ETag . . . . . . . . . . . . . . . . . . . . . . . . . . 136
14.20. Expect . . . . . . . . . . . . . . . . . . . . . . . . . 137 14.20. Expect . . . . . . . . . . . . . . . . . . . . . . . . . 136
14.21. Expires . . . . . . . . . . . . . . . . . . . . . . . . 138 14.21. Expires . . . . . . . . . . . . . . . . . . . . . . . . 137
14.22. From . . . . . . . . . . . . . . . . . . . . . . . . . . 139 14.22. From . . . . . . . . . . . . . . . . . . . . . . . . . . 138
14.23. Host . . . . . . . . . . . . . . . . . . . . . . . . . . 140 14.23. Host . . . . . . . . . . . . . . . . . . . . . . . . . . 138
14.24. If-Match . . . . . . . . . . . . . . . . . . . . . . . . 140 14.24. If-Match . . . . . . . . . . . . . . . . . . . . . . . . 139
14.25. If-Modified-Since . . . . . . . . . . . . . . . . . . . 141 14.25. If-Modified-Since . . . . . . . . . . . . . . . . . . . 140
14.26. If-None-Match . . . . . . . . . . . . . . . . . . . . . 143 14.26. If-None-Match . . . . . . . . . . . . . . . . . . . . . 142
14.27. If-Range . . . . . . . . . . . . . . . . . . . . . . . . 144 14.27. If-Range . . . . . . . . . . . . . . . . . . . . . . . . 143
14.28. If-Unmodified-Since . . . . . . . . . . . . . . . . . . 145 14.28. If-Unmodified-Since . . . . . . . . . . . . . . . . . . 144
14.29. Last-Modified . . . . . . . . . . . . . . . . . . . . . 145 14.29. Last-Modified . . . . . . . . . . . . . . . . . . . . . 144
14.30. Location . . . . . . . . . . . . . . . . . . . . . . . . 146 14.30. Location . . . . . . . . . . . . . . . . . . . . . . . . 145
14.31. Max-Forwards . . . . . . . . . . . . . . . . . . . . . . 147 14.31. Max-Forwards . . . . . . . . . . . . . . . . . . . . . . 146
14.32. Pragma . . . . . . . . . . . . . . . . . . . . . . . . . 147 14.32. Pragma . . . . . . . . . . . . . . . . . . . . . . . . . 146
14.33. Proxy-Authenticate . . . . . . . . . . . . . . . . . . . 148 14.33. Proxy-Authenticate . . . . . . . . . . . . . . . . . . . 147
14.34. Proxy-Authorization . . . . . . . . . . . . . . . . . . 149 14.34. Proxy-Authorization . . . . . . . . . . . . . . . . . . 147
14.35. Range . . . . . . . . . . . . . . . . . . . . . . . . . 149 14.35. Range . . . . . . . . . . . . . . . . . . . . . . . . . 148
14.35.1. Byte Ranges . . . . . . . . . . . . . . . . . . . . 149 14.35.1. Byte Ranges . . . . . . . . . . . . . . . . . . . . 148
14.35.2. Range Retrieval Requests . . . . . . . . . . . . . . 151 14.35.2. Range Retrieval Requests . . . . . . . . . . . . . . 149
14.36. Referer . . . . . . . . . . . . . . . . . . . . . . . . 152 14.36. Referer . . . . . . . . . . . . . . . . . . . . . . . . 150
14.37. Retry-After . . . . . . . . . . . . . . . . . . . . . . 152 14.37. Retry-After . . . . . . . . . . . . . . . . . . . . . . 151
14.38. Server . . . . . . . . . . . . . . . . . . . . . . . . . 152 14.38. Server . . . . . . . . . . . . . . . . . . . . . . . . . 151
14.39. TE . . . . . . . . . . . . . . . . . . . . . . . . . . . 153 14.39. TE . . . . . . . . . . . . . . . . . . . . . . . . . . . 152
14.40. Trailer . . . . . . . . . . . . . . . . . . . . . . . . 154 14.40. Trailer . . . . . . . . . . . . . . . . . . . . . . . . 153
14.41. Transfer-Encoding . . . . . . . . . . . . . . . . . . . 155 14.41. Transfer-Encoding . . . . . . . . . . . . . . . . . . . 153
14.42. Upgrade . . . . . . . . . . . . . . . . . . . . . . . . 155 14.42. Upgrade . . . . . . . . . . . . . . . . . . . . . . . . 154
14.43. User-Agent . . . . . . . . . . . . . . . . . . . . . . . 156 14.43. User-Agent . . . . . . . . . . . . . . . . . . . . . . . 155
14.44. Vary . . . . . . . . . . . . . . . . . . . . . . . . . . 157 14.44. Vary . . . . . . . . . . . . . . . . . . . . . . . . . . 155
14.45. Via . . . . . . . . . . . . . . . . . . . . . . . . . . 157 14.45. Via . . . . . . . . . . . . . . . . . . . . . . . . . . 156
14.46. Warning . . . . . . . . . . . . . . . . . . . . . . . . 159 14.46. Warning . . . . . . . . . . . . . . . . . . . . . . . . 158
14.47. WWW-Authenticate . . . . . . . . . . . . . . . . . . . . 162 14.47. WWW-Authenticate . . . . . . . . . . . . . . . . . . . . 160
15. Security Considerations . . . . . . . . . . . . . . . . . . . 163 15. Security Considerations . . . . . . . . . . . . . . . . . . . 161
15.1. Personal Information . . . . . . . . . . . . . . . . . . 163 15.1. Personal Information . . . . . . . . . . . . . . . . . . 161
15.1.1. Abuse of Server Log Information . . . . . . . . . . 163 15.1.1. Abuse of Server Log Information . . . . . . . . . . 161
15.1.2. Transfer of Sensitive Information . . . . . . . . . 163 15.1.2. Transfer of Sensitive Information . . . . . . . . . 161
15.1.3. Encoding Sensitive Information in URI's . . . . . . 164 15.1.3. Encoding Sensitive Information in URI's . . . . . . 162
15.1.4. Privacy Issues Connected to Accept Headers . . . . . 165 15.1.4. Privacy Issues Connected to Accept Headers . . . . . 163
15.2. Attacks Based On File and Path Names . . . . . . . . . . 165 15.2. Attacks Based On File and Path Names . . . . . . . . . . 163
15.3. DNS Spoofing . . . . . . . . . . . . . . . . . . . . . . 166 15.3. DNS Spoofing . . . . . . . . . . . . . . . . . . . . . . 164
15.4. Location Headers and Spoofing . . . . . . . . . . . . . 166 15.4. Location Headers and Spoofing . . . . . . . . . . . . . 164
15.5. Content-Disposition Issues . . . . . . . . . . . . . . . 167 15.5. Content-Disposition Issues . . . . . . . . . . . . . . . 165
15.6. Authentication Credentials and Idle Clients . . . . . . 167 15.6. Authentication Credentials and Idle Clients . . . . . . 165
15.7. Proxies and Caching . . . . . . . . . . . . . . . . . . 167 15.7. Proxies and Caching . . . . . . . . . . . . . . . . . . 165
15.7.1. Denial of Service Attacks on Proxies . . . . . . . . 168 15.7.1. Denial of Service Attacks on Proxies . . . . . . . . 166
16. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 169 16. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 167
16.1. (RFC2616) . . . . . . . . . . . . . . . . . . . . . . . 169 16.1. (RFC2616) . . . . . . . . . . . . . . . . . . . . . . . 167
16.2. (This Document) . . . . . . . . . . . . . . . . . . . . 170 16.2. (This Document) . . . . . . . . . . . . . . . . . . . . 168
17. References . . . . . . . . . . . . . . . . . . . . . . . . . 171 17. References . . . . . . . . . . . . . . . . . . . . . . . . . 169
17.1. References . . . . . . . . . . . . . . . . . . . . . . . 171 17.1. References . . . . . . . . . . . . . . . . . . . . . . . 169
17.2. Informative References . . . . . . . . . . . . . . . . . 174 17.2. Informative References . . . . . . . . . . . . . . . . . 173
Appendix A. Internet Media Type message/http and Appendix A. Internet Media Type message/http and
application/http . . . . . . . . . . . . . . . . . . 176 application/http . . . . . . . . . . . . . . . . . . 175
Appendix B. Internet Media Type multipart/byteranges . . . . . . 178 Appendix B. Internet Media Type multipart/byteranges . . . . . . 177
Appendix C. Tolerant Applications . . . . . . . . . . . . . . . 180 Appendix C. Tolerant Applications . . . . . . . . . . . . . . . 179
Appendix D. Differences Between HTTP Entities and RFC 2045 Appendix D. Differences Between HTTP Entities and RFC 2045
Entities . . . . . . . . . . . . . . . . . . . . . . 181 Entities . . . . . . . . . . . . . . . . . . . . . . 180
D.1. MIME-Version . . . . . . . . . . . . . . . . . . . . . . 181 D.1. MIME-Version . . . . . . . . . . . . . . . . . . . . . . 180
D.2. Conversion to Canonical Form . . . . . . . . . . . . . . 181 D.2. Conversion to Canonical Form . . . . . . . . . . . . . . 180
D.3. Conversion of Date Formats . . . . . . . . . . . . . . . 182 D.3. Conversion of Date Formats . . . . . . . . . . . . . . . 181
D.4. Introduction of Content-Encoding . . . . . . . . . . . . 182 D.4. Introduction of Content-Encoding . . . . . . . . . . . . 181
D.5. No Content-Transfer-Encoding . . . . . . . . . . . . . . 182 D.5. No Content-Transfer-Encoding . . . . . . . . . . . . . . 181
D.6. Introduction of Transfer-Encoding . . . . . . . . . . . 183 D.6. Introduction of Transfer-Encoding . . . . . . . . . . . 182
D.7. MHTML and Line Length Limitations . . . . . . . . . . . 183 D.7. MHTML and Line Length Limitations . . . . . . . . . . . 182
Appendix E. Additional Features . . . . . . . . . . . . . . . . 184 Appendix E. Additional Features . . . . . . . . . . . . . . . . 183
E.1. Content-Disposition . . . . . . . . . . . . . . . . . . 184 E.1. Content-Disposition . . . . . . . . . . . . . . . . . . 183
Appendix F. Compatibility with Previous Versions . . . . . . . . 185 Appendix F. Compatibility with Previous Versions . . . . . . . . 184
F.1. Changes from HTTP/1.0 . . . . . . . . . . . . . . . . . 185 F.1. Changes from HTTP/1.0 . . . . . . . . . . . . . . . . . 184
F.1.1. Changes to Simplify Multi-homed Web Servers and F.1.1. Changes to Simplify Multi-homed Web Servers and
Conserve IP Addresses . . . . . . . . . . . . . . . 185 Conserve IP Addresses . . . . . . . . . . . . . . . 184
F.2. Compatibility with HTTP/1.0 Persistent Connections . . . 186 F.2. Compatibility with HTTP/1.0 Persistent Connections . . . 185
F.3. Changes from RFC 2068 . . . . . . . . . . . . . . . . . 187 F.3. Changes from RFC 2068 . . . . . . . . . . . . . . . . . 186
F.4. Changes from RFC 2616 . . . . . . . . . . . . . . . . . 189 F.4. Changes from RFC 2616 . . . . . . . . . . . . . . . . . 188
Appendix G. Change Log (to be removed by RFC Editor before Appendix G. Change Log (to be removed by RFC Editor before
publication) . . . . . . . . . . . . . . . . . . . . 191 publication) . . . . . . . . . . . . . . . . . . . . 190
G.1. Since RFC2616 . . . . . . . . . . . . . . . . . . . . . 191 G.1. Since RFC2616 . . . . . . . . . . . . . . . . . . . . . 190
G.2. Since draft-lafon-rfc2616bis-00 . . . . . . . . . . . . 191 G.2. Since draft-lafon-rfc2616bis-00 . . . . . . . . . . . . 190
G.3. Since draft-lafon-rfc2616bis-01 . . . . . . . . . . . . 190
Appendix H. Resolved issues (to be removed by RFC Editor Appendix H. Resolved issues (to be removed by RFC Editor
before publication) . . . . . . . . . . . . . . . . 192 before publication) . . . . . . . . . . . . . . . . 191
H.1. rfc2606-compliance . . . . . . . . . . . . . . . . . . . 192 H.1. rfc2606-compliance . . . . . . . . . . . . . . . . . . . 191
H.2. editor-notes . . . . . . . . . . . . . . . . . . . . . . 192 H.2. references_style . . . . . . . . . . . . . . . . . . . . 191
H.3. verscase . . . . . . . . . . . . . . . . . . . . . . . . 192 H.3. media-reg . . . . . . . . . . . . . . . . . . . . . . . 191
H.4. unsafe-uri . . . . . . . . . . . . . . . . . . . . . . . 192 H.4. location-fragments . . . . . . . . . . . . . . . . . . . 192
H.5. charactersets . . . . . . . . . . . . . . . . . . . . . 193
H.6. identity . . . . . . . . . . . . . . . . . . . . . . . . 193
H.7. chunk-size . . . . . . . . . . . . . . . . . . . . . . . 193
H.8. msg-len-chars . . . . . . . . . . . . . . . . . . . . . 194
H.9. uriquery . . . . . . . . . . . . . . . . . . . . . . . . 194
H.10. post . . . . . . . . . . . . . . . . . . . . . . . . . . 194
H.11. ifrange206 . . . . . . . . . . . . . . . . . . . . . . . 194
H.12. saferedirect . . . . . . . . . . . . . . . . . . . . . . 195
H.13. trailer-hop . . . . . . . . . . . . . . . . . . . . . . 195
H.14. invalidupd . . . . . . . . . . . . . . . . . . . . . . . 195
H.15. noclose1xx . . . . . . . . . . . . . . . . . . . . . . . 196
H.16. via-must . . . . . . . . . . . . . . . . . . . . . . . . 196
Appendix I. Open issues (to be removed by RFC Editor prior to Appendix I. Open issues (to be removed by RFC Editor prior to
publication) . . . . . . . . . . . . . . . . . . . . 197 publication) . . . . . . . . . . . . . . . . . . . . 193
I.1. rfc2616bis . . . . . . . . . . . . . . . . . . . . . . . 197 I.1. rfc2616bis . . . . . . . . . . . . . . . . . . . . . . . 193
I.2. unneeded_references . . . . . . . . . . . . . . . . . . 197 I.2. unneeded_references . . . . . . . . . . . . . . . . . . 193
I.3. edit . . . . . . . . . . . . . . . . . . . . . . . . . . 197 I.3. edit . . . . . . . . . . . . . . . . . . . . . . . . . . 193
I.4. media-reg . . . . . . . . . . . . . . . . . . . . . . . 197 I.4. rfc2048_informative_and_obsolete . . . . . . . . . . . . 193
I.5. languagetag . . . . . . . . . . . . . . . . . . . . . . 197 I.5. languagetag . . . . . . . . . . . . . . . . . . . . . . 193
I.6. location-fragments . . . . . . . . . . . . . . . . . . . 198 I.6. fragment-combination . . . . . . . . . . . . . . . . . . 194
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 199 Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 210 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 206
Intellectual Property and Copyright Statements . . . . . . . . . 213 Intellectual Property and Copyright Statements . . . . . . . . . 209
1. Introduction 1. Introduction
1.1. Purpose 1.1. Purpose
The Hypertext Transfer Protocol (HTTP) is an application-level The Hypertext Transfer Protocol (HTTP) is an application-level
protocol for distributed, collaborative, hypermedia information protocol for distributed, collaborative, hypermedia information
systems. HTTP has been in use by the World-Wide Web global systems. HTTP has been in use by the World-Wide Web global
information initiative since 1990. The first version of HTTP, information initiative since 1990. The first version of HTTP,
referred to as HTTP/0.9, was a simple protocol for raw data transfer referred to as HTTP/0.9, was a simple protocol for raw data transfer
across the Internet. HTTP/1.0, as defined by RFC 1945 [6], improved across the Internet. HTTP/1.0, as defined by [RFC1945], improved the
the protocol by allowing messages to be in the format of MIME-like protocol by allowing messages to be in the format of MIME-like
messages, containing metainformation about the data transferred and messages, containing metainformation about the data transferred and
modifiers on the request/response semantics. However, HTTP/1.0 does modifiers on the request/response semantics. However, HTTP/1.0 does
not sufficiently take into consideration the effects of hierarchical not sufficiently take into consideration the effects of hierarchical
proxies, caching, the need for persistent connections, or virtual proxies, caching, the need for persistent connections, or virtual
hosts. In addition, the proliferation of incompletely-implemented hosts. In addition, the proliferation of incompletely-implemented
applications calling themselves "HTTP/1.0" has necessitated a applications calling themselves "HTTP/1.0" has necessitated a
protocol version change in order for two communicating applications protocol version change in order for two communicating applications
to determine each other's true capabilities. to determine each other's true capabilities.
This specification defines the protocol referred to as "HTTP/1.1". This specification defines the protocol referred to as "HTTP/1.1".
This protocol includes more stringent requirements than HTTP/1.0 in This protocol includes more stringent requirements than HTTP/1.0 in
order to ensure reliable implementation of its features. order to ensure reliable implementation of its features.
Practical information systems require more functionality than simple Practical information systems require more functionality than simple
retrieval, including search, front-end update, and annotation. HTTP retrieval, including search, front-end update, and annotation. HTTP
allows an open-ended set of methods and headers that indicate the allows an open-ended set of methods and headers that indicate the
purpose of a request [47]. It builds on the discipline of reference purpose of a request [RFC2324]. It builds on the discipline of
provided by the Uniform Resource Identifier (URI) [3], as a location reference provided by the Uniform Resource Identifier (URI)
(URL) [4] or name (URN) [20], for indicating the resource to which a [RFC1630], as a location (URL) [RFC1738] or name (URN) [RFC1737], for
method is to be applied. Messages are passed in a format similar to indicating the resource to which a method is to be applied. Messages
that used by Internet mail [9] as defined by the Multipurpose are passed in a format similar to that used by Internet mail [RFC822]
Internet Mail Extensions (MIME) [7]. as defined by the Multipurpose Internet Mail Extensions (MIME)
[RFC2045].
HTTP is also used as a generic protocol for communication between HTTP is also used as a generic protocol for communication between
user agents and proxies/gateways to other Internet systems, including user agents and proxies/gateways to other Internet systems, including
those supported by the SMTP [16], NNTP [13], FTP [18], Gopher [2], those supported by the SMTP [RFC821], NNTP [RFC977], FTP [RFC959],
and WAIS [10] protocols. In this way, HTTP allows basic hypermedia Gopher [RFC1436], and WAIS [WAIS] protocols. In this way, HTTP
access to resources available from diverse applications. allows basic hypermedia access to resources available from diverse
applications.
1.2. Requirements 1.2. Requirements
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [34]. document are to be interpreted as described in [RFC2119].
An implementation is not compliant if it fails to satisfy one or more An implementation is not compliant if it fails to satisfy one or more
of the MUST or REQUIRED level requirements for the protocols it of the MUST or REQUIRED level requirements for the protocols it
implements. An implementation that satisfies all the MUST or implements. An implementation that satisfies all the MUST or
REQUIRED level and all the SHOULD level requirements for its REQUIRED level and all the SHOULD level requirements for its
protocols is said to be "unconditionally compliant"; one that protocols is said to be "unconditionally compliant"; one that
satisfies all the MUST level requirements but not all the SHOULD satisfies all the MUST level requirements but not all the SHOULD
level requirements for its protocols is said to be "conditionally level requirements for its protocols is said to be "conditionally
compliant." compliant."
skipping to change at page 18, line 4 skipping to change at page 17, line 4
subsets of cached data via CD-ROM, and so on. HTTP systems are used subsets of cached data via CD-ROM, and so on. HTTP systems are used
in corporate intranets over high-bandwidth links, and for access via in corporate intranets over high-bandwidth links, and for access via
PDAs with low-power radio links and intermittent connectivity. The PDAs with low-power radio links and intermittent connectivity. The
goal of HTTP/1.1 is to support the wide diversity of configurations goal of HTTP/1.1 is to support the wide diversity of configurations
already deployed while introducing protocol constructs that meet the already deployed while introducing protocol constructs that meet the
needs of those who build web applications that require high needs of those who build web applications that require high
reliability and, failing that, at least reliable indications of reliability and, failing that, at least reliable indications of
failure. failure.
HTTP communication usually takes place over TCP/IP connections. The HTTP communication usually takes place over TCP/IP connections. The
default port is TCP 80 [19], but other ports can be used. This does default port is TCP 80 [RFC1700], but other ports can be used. This
not preclude HTTP from being implemented on top of any other protocol does not preclude HTTP from being implemented on top of any other
on the Internet, or on other networks. HTTP only presumes a reliable protocol on the Internet, or on other networks. HTTP only presumes a
transport; any protocol that provides such guarantees can be used; reliable transport; any protocol that provides such guarantees can be
the mapping of the HTTP/1.1 request and response structures onto the used; the mapping of the HTTP/1.1 request and response structures
transport data units of the protocol in question is outside the scope onto the transport data units of the protocol in question is outside
of this specification. the scope of this specification.
In HTTP/1.0, most implementations used a new connection for each In HTTP/1.0, most implementations used a new connection for each
request/response exchange. In HTTP/1.1, a connection may be used for request/response exchange. In HTTP/1.1, a connection may be used for
one or more request/response exchanges, although connections may be one or more request/response exchanges, although connections may be
closed for a variety of reasons (see Section 8.1). closed for a variety of reasons (see Section 8.1).
2. Notational Conventions and Generic Grammar 2. Notational Conventions and Generic Grammar
2.1. Augmented BNF 2.1. Augmented BNF
All of the mechanisms specified in this document are described in All of the mechanisms specified in this document are described in
both prose and an augmented Backus-Naur Form (BNF) similar to that both prose and an augmented Backus-Naur Form (BNF) similar to that
used by RFC 822 [9]. Implementors will need to be familiar with the used by [RFC822]. Implementors will need to be familiar with the
notation in order to understand this specification. The augmented notation in order to understand this specification. The augmented
BNF includes the following constructs: BNF includes the following constructs:
name = definition name = definition
The name of a rule is simply the name itself (without any The name of a rule is simply the name itself (without any
enclosing "<" and ">") and is separated from its definition by the enclosing "<" and ">") and is separated from its definition by the
equal "=" character. White space is only significant in that equal "=" character. White space is only significant in that
indentation of continuation lines is used to indicate a rule indentation of continuation lines is used to indicate a rule
definition that spans more than one line. Certain basic rules are definition that spans more than one line. Certain basic rules are
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between adjacent words and separators, without changing the between adjacent words and separators, without changing the
interpretation of a field. At least one delimiter (LWS and/or interpretation of a field. At least one delimiter (LWS and/or
separators) MUST exist between any two tokens (for the definition separators) MUST exist between any two tokens (for the definition
of "token" below), since they would otherwise be interpreted as a of "token" below), since they would otherwise be interpreted as a
single token. single token.
2.2. Basic Rules 2.2. Basic Rules
The following rules are used throughout this specification to The following rules are used throughout this specification to
describe basic parsing constructs. The US-ASCII coded character set describe basic parsing constructs. The US-ASCII coded character set
is defined by ANSI X3.4-1986 [21]. is defined by ANSI X3.4-1986 [USASCII].
OCTET = <any 8-bit sequence of data> OCTET = <any 8-bit sequence of data>
CHAR = <any US-ASCII character (octets 0 - 127)> CHAR = <any US-ASCII character (octets 0 - 127)>
UPALPHA = <any US-ASCII uppercase letter "A".."Z"> UPALPHA = <any US-ASCII uppercase letter "A".."Z">
LOALPHA = <any US-ASCII lowercase letter "a".."z"> LOALPHA = <any US-ASCII lowercase letter "a".."z">
ALPHA = UPALPHA | LOALPHA ALPHA = UPALPHA | LOALPHA
DIGIT = <any US-ASCII digit "0".."9"> DIGIT = <any US-ASCII digit "0".."9">
CTL = <any US-ASCII control character CTL = <any US-ASCII control character
(octets 0 - 31) and DEL (127)> (octets 0 - 31) and DEL (127)>
CR = <US-ASCII CR, carriage return (13)> CR = <US-ASCII CR, carriage return (13)>
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continuation line begins with a space or horizontal tab. All linear continuation line begins with a space or horizontal tab. All linear
white space, including folding, has the same semantics as SP. A white space, including folding, has the same semantics as SP. A
recipient MAY replace any linear white space with a single SP before recipient MAY replace any linear white space with a single SP before
interpreting the field value or forwarding the message downstream. interpreting the field value or forwarding the message downstream.
LWS = [CRLF] 1*( SP | HT ) LWS = [CRLF] 1*( SP | HT )
The TEXT rule is only used for descriptive field contents and values The TEXT rule is only used for descriptive field contents and values
that are not intended to be interpreted by the message parser. Words that are not intended to be interpreted by the message parser. Words
of *TEXT MAY contain characters from character sets other than ISO- of *TEXT MAY contain characters from character sets other than ISO-
8859-1 [22] only when encoded according to the rules of RFC 2047 8859-1 [ISO-8859] only when encoded according to the rules of
[14]. [RFC2047].
TEXT = <any OCTET except CTLs, TEXT = <any OCTET except CTLs,
but including LWS> but including LWS>
A CRLF is allowed in the definition of TEXT only as part of a header A CRLF is allowed in the definition of TEXT only as part of a header
field continuation. It is expected that the folding LWS will be field continuation. It is expected that the folding LWS will be
replaced with a single SP before interpretation of the TEXT value. replaced with a single SP before interpretation of the TEXT value.
Hexadecimal numeric characters are used in several protocol elements. Hexadecimal numeric characters are used in several protocol elements.
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the sender to indicate the format of a message and its capacity for the sender to indicate the format of a message and its capacity for
understanding further HTTP communication, rather than the features understanding further HTTP communication, rather than the features
obtained via that communication. No change is made to the version obtained via that communication. No change is made to the version
number for the addition of message components which do not affect number for the addition of message components which do not affect
communication behavior or which only add to extensible field values. communication behavior or which only add to extensible field values.
The <minor> number is incremented when the changes made to the The <minor> number is incremented when the changes made to the
protocol add features which do not change the general message parsing protocol add features which do not change the general message parsing
algorithm, but which may add to the message semantics and imply algorithm, but which may add to the message semantics and imply
additional capabilities of the sender. The <major> number is additional capabilities of the sender. The <major> number is
incremented when the format of a message within the protocol is incremented when the format of a message within the protocol is
changed. See RFC 2145 [36] for a fuller explanation. changed. See [RFC2145] for a fuller explanation.
The version of an HTTP message is indicated by an HTTP-Version field The version of an HTTP message is indicated by an HTTP-Version field
in the first line of the message. in the first line of the message.
HTTP-Version = "HTTP" "/" 1*DIGIT "." 1*DIGIT HTTP-Version = "HTTP" "/" 1*DIGIT "." 1*DIGIT
Note that the major and minor numbers MUST be treated as separate Note that the major and minor numbers MUST be treated as separate
integers and that each MAY be incremented higher than a single digit. integers and that each MAY be incremented higher than a single digit.
Thus, HTTP/2.4 is a lower version than HTTP/2.13, which in turn is Thus, HTTP/2.4 is a lower version than HTTP/2.13, which in turn is
lower than HTTP/12.3. Leading zeros MUST be ignored by recipients lower than HTTP/12.3. Leading zeros MUST be ignored by recipients
and MUST NOT be sent. and MUST NOT be sent.
An application that sends a request or response message that includes An application that sends a request or response message that includes
HTTP-Version of "HTTP/1.1" MUST be at least conditionally compliant HTTP-Version of "HTTP/1.1" MUST be at least conditionally compliant
with this specification. Applications that are at least with this specification. Applications that are at least
conditionally compliant with this specification SHOULD use an HTTP- conditionally compliant with this specification SHOULD use an HTTP-
Version of "HTTP/1.1" in their messages, and MUST do so for any Version of "HTTP/1.1" in their messages, and MUST do so for any
message that is not compatible with HTTP/1.0. For more details on message that is not compatible with HTTP/1.0. For more details on
when to send specific HTTP-Version values, see RFC 2145 [36]. when to send specific HTTP-Version values, see [RFC2145].
The HTTP version of an application is the highest HTTP version for The HTTP version of an application is the highest HTTP version for
which the application is at least conditionally compliant. HTTP- which the application is at least conditionally compliant. HTTP-
Version is case-sensitive. Version is case-sensitive.
Proxy and gateway applications need to be careful when forwarding Proxy and gateway applications need to be careful when forwarding
messages in protocol versions different from that of the application. messages in protocol versions different from that of the application.
Since the protocol version indicates the protocol capability of the Since the protocol version indicates the protocol capability of the
sender, a proxy/gateway MUST NOT send a message with a version sender, a proxy/gateway MUST NOT send a message with a version
indicator which is greater than its actual version. If a higher indicator which is greater than its actual version. If a higher
version request is received, the proxy/gateway MUST either downgrade version request is received, the proxy/gateway MUST either downgrade
the request version, or respond with an error, or switch to tunnel the request version, or respond with an error, or switch to tunnel
behavior. behavior.
Due to interoperability problems with HTTP/1.0 proxies discovered Due to interoperability problems with HTTP/1.0 proxies discovered
since the publication of RFC 2068 [33], caching proxies MUST, since the publication of [RFC2068], caching proxies MUST, gateways
gateways MAY, and tunnels MUST NOT upgrade the request to the highest MAY, and tunnels MUST NOT upgrade the request to the highest version
version they support. The proxy/gateway's response to that request they support. The proxy/gateway's response to that request MUST be
MUST be in the same major version as the request. in the same major version as the request.
Note: Converting between versions of HTTP may involve modification Note: Converting between versions of HTTP may involve modification
of header fields required or forbidden by the versions involved. of header fields required or forbidden by the versions involved.
3.2. Uniform Resource Identifiers 3.2. Uniform Resource Identifiers
URIs have been known by many names: WWW addresses, Universal Document URIs have been known by many names: WWW addresses, Universal Document
Identifiers, Universal Resource Identifiers [3], and finally the Identifiers, Universal Resource Identifiers [RFC1630], and finally
combination of Uniform Resource Locators (URL) [4] and Names (URN) the combination of Uniform Resource Locators (URL) [RFC1738] and
[20]. As far as HTTP is concerned, Uniform Resource Identifiers are Names (URN) [RFC1737]. As far as HTTP is concerned, Uniform Resource
simply formatted strings which identify--via name, location, or any Identifiers are simply formatted strings which identify--via name,
other characteristic--a resource. location, or any other characteristic--a resource.
3.2.1. General Syntax 3.2.1. General Syntax
URIs in HTTP can be represented in absolute form or relative to some URIs in HTTP can be represented in absolute form or relative to some
known base URI [11], depending upon the context of their use. The known base URI [RFC1808], depending upon the context of their use.
two forms are differentiated by the fact that absolute URIs always The two forms are differentiated by the fact that absolute URIs
begin with a scheme name followed by a colon. For definitive always begin with a scheme name followed by a colon. For definitive
information on URL syntax and semantics, see "Uniform Resource information on URL syntax and semantics, see "Uniform Resource
Identifiers (URI): Generic Syntax and Semantics," RFC 2396 [42] Identifiers (URI): Generic Syntax and Semantics," [RFC2396] (which
(which replaces RFCs 1738 [4] and RFC 1808 [11]). This specification replaces [RFC1738] and [RFC1808]). This specification adopts the
adopts the definitions of "URI-reference", "absoluteURI", definitions of "URI-reference", "absoluteURI", "relativeURI", "port",
"relativeURI", "port", "host","abs_path", "rel_path", and "authority" "host","abs_path", "rel_path", and "authority" from that
from that specification. specification.
The HTTP protocol does not place any a priori limit on the length of The HTTP protocol does not place any a priori limit on the length of
a URI. Servers MUST be able to handle the URI of any resource they a URI. Servers MUST be able to handle the URI of any resource they
serve, and SHOULD be able to handle URIs of unbounded length if they serve, and SHOULD be able to handle URIs of unbounded length if they
provide GET-based forms that could generate such URIs. A server provide GET-based forms that could generate such URIs. A server
SHOULD return 414 (Request-URI Too Long) status if a URI is longer SHOULD return 414 (Request-URI Too Long) status if a URI is longer
than the server can handle (see Section 10.4.15). than the server can handle (see Section 10.4.15).
Note: Servers ought to be cautious about depending on URI lengths Note: Servers ought to be cautious about depending on URI lengths
above 255 bytes, because some older client or proxy above 255 bytes, because some older client or proxy
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The "http" scheme is used to locate network resources via the HTTP The "http" scheme is used to locate network resources via the HTTP
protocol. This section defines the scheme-specific syntax and protocol. This section defines the scheme-specific syntax and
semantics for http URLs. semantics for http URLs.
http_URL = "http:" "//" host [ ":" port ] [ abs_path [ "?" query ]] http_URL = "http:" "//" host [ ":" port ] [ abs_path [ "?" query ]]
If the port is empty or not given, port 80 is assumed. The semantics If the port is empty or not given, port 80 is assumed. The semantics
are that the identified resource is located at the server listening are that the identified resource is located at the server listening
for TCP connections on that port of that host, and the Request-URI for TCP connections on that port of that host, and the Request-URI
for the resource is abs_path (Section 5.1.2). The use of IP for the resource is abs_path (Section 5.1.2). The use of IP
addresses in URLs SHOULD be avoided whenever possible (see RFC 1900 addresses in URLs SHOULD be avoided whenever possible (see
[24]). If the abs_path is not present in the URL, it MUST be given [RFC1900]). If the abs_path is not present in the URL, it MUST be
as "/" when used as a Request-URI for a resource (Section 5.1.2). If given as "/" when used as a Request-URI for a resource
a proxy receives a host name which is not a fully qualified domain (Section 5.1.2). If a proxy receives a host name which is not a
name, it MAY add its domain to the host name it received. If a proxy fully qualified domain name, it MAY add its domain to the host name
receives a fully qualified domain name, the proxy MUST NOT change the it received. If a proxy receives a fully qualified domain name, the
host name. proxy MUST NOT change the host name.
3.2.3. URI Comparison 3.2.3. URI Comparison
When comparing two URIs to decide if they match or not, a client When comparing two URIs to decide if they match or not, a client
SHOULD use a case-sensitive octet-by-octet comparison of the entire SHOULD use a case-sensitive octet-by-octet comparison of the entire
URIs, with these exceptions: URIs, with these exceptions:
o A port that is empty or not given is equivalent to the default o A port that is empty or not given is equivalent to the default
port for that URI-reference; port for that URI-reference;
o Comparisons of host names MUST be case-insensitive; o Comparisons of host names MUST be case-insensitive;
o Comparisons of scheme names MUST be case-insensitive; o Comparisons of scheme names MUST be case-insensitive;
o An empty abs_path is equivalent to an abs_path of "/". o An empty abs_path is equivalent to an abs_path of "/".
Characters other than those in the "reserved" set (see RFC 2396 [42]) Characters other than those in the "reserved" set (see [RFC2396]) are
are equivalent to their ""%" HEX HEX" encoding. equivalent to their ""%" HEX HEX" encoding.
For example, the following three URIs are equivalent: For example, the following three URIs are equivalent:
http://abc.com:80/~smith/home.html http://example.com:80/~smith/home.html
http://ABC.com/%7Esmith/home.html http://EXAMPLE.com/%7Esmith/home.html
http://ABC.com:/%7esmith/home.html http://EXAMPLE.com:/%7esmith/home.html
3.3. Date/Time Formats 3.3. Date/Time Formats
3.3.1. Full Date 3.3.1. Full Date
HTTP applications have historically allowed three different formats HTTP applications have historically allowed three different formats
for the representation of date/time stamps: for the representation of date/time stamps:
Sun, 06 Nov 1994 08:49:37 GMT ; RFC 822, updated by RFC 1123 Sun, 06 Nov 1994 08:49:37 GMT ; [RFC822], updated by [RFC1123]
Sunday, 06-Nov-94 08:49:37 GMT ; RFC 850, obsoleted by RFC 1036 Sunday, 06-Nov-94 08:49:37 GMT ; RFC 850, obsoleted by [RFC1036]
Sun Nov 6 08:49:37 1994 ; ANSI C's asctime() format Sun Nov 6 08:49:37 1994 ; ANSI C's asctime() format
The first format is preferred as an Internet standard and represents The first format is preferred as an Internet standard and represents
a fixed-length subset of that defined by RFC 1123 [8] (an update to a fixed-length subset of that defined by [RFC1123] (an update to
RFC 822 [9]). The second format is in common use, but is based on [RFC822]). The second format is in common use, but is based on the
the obsolete RFC 850 [12] date format and lacks a four-digit year. obsolete RFC 850 [RFC1036] date format and lacks a four-digit year.
HTTP/1.1 clients and servers that parse the date value MUST accept HTTP/1.1 clients and servers that parse the date value MUST accept
all three formats (for compatibility with HTTP/1.0), though they MUST all three formats (for compatibility with HTTP/1.0), though they MUST
only generate the RFC 1123 format for representing HTTP-date values only generate the RFC 1123 format for representing HTTP-date values
in header fields. See Appendix C for further information. in header fields. See Appendix C for further information.
Note: Recipients of date values are encouraged to be robust in Note: Recipients of date values are encouraged to be robust in
accepting date values that may have been sent by non-HTTP accepting date values that may have been sent by non-HTTP
applications, as is sometimes the case when retrieving or posting applications, as is sometimes the case when retrieving or posting
messages via proxies/gateways to SMTP or NNTP. messages via proxies/gateways to SMTP or NNTP.
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to characters. In particular, use of external profiling information to characters. In particular, use of external profiling information
to determine the exact mapping is not permitted. to determine the exact mapping is not permitted.
Note: This use of the term "character set" is more commonly Note: This use of the term "character set" is more commonly
referred to as a "character encoding." However, since HTTP and referred to as a "character encoding." However, since HTTP and
MIME share the same registry, it is important that the terminology MIME share the same registry, it is important that the terminology
also be shared. also be shared.
HTTP character sets are identified by case-insensitive tokens. The HTTP character sets are identified by case-insensitive tokens. The
complete set of tokens is defined by the IANA Character Set registry complete set of tokens is defined by the IANA Character Set registry
[19]. [RFC1700].
charset = token charset = token
Although HTTP allows an arbitrary token to be used as a charset Although HTTP allows an arbitrary token to be used as a charset
value, any token that has a predefined value within the IANA value, any token that has a predefined value within the IANA
Character Set registry [19] MUST represent the character set defined Character Set registry [RFC1700] MUST represent the character set
by that registry. Applications SHOULD limit their use of character defined by that registry. Applications SHOULD limit their use of
sets to those defined by the IANA registry. character sets to those defined by the IANA registry.
HTTP uses charset in two contexts: within an Accept-Charset request HTTP uses charset in two contexts: within an Accept-Charset request
header (in which the charset value is an unquoted token) and as the header (in which the charset value is an unquoted token) and as the
value of a parameter in a Content-Type header (within a request or value of a parameter in a Content-Type header (within a request or
response), in which case the parameter value of the charset parameter response), in which case the parameter value of the charset parameter
may be quoted. may be quoted.
Implementors should be aware of IETF character set requirements [38] Implementors should be aware of IETF character set requirements
[41]. [RFC2279] [RFC2277].
3.4.1. Missing Charset 3.4.1. Missing Charset
Some HTTP/1.0 software has interpreted a Content-Type header without Some HTTP/1.0 software has interpreted a Content-Type header without
charset parameter incorrectly to mean "recipient should guess." charset parameter incorrectly to mean "recipient should guess."
Senders wishing to defeat this behavior MAY include a charset Senders wishing to defeat this behavior MAY include a charset
parameter even when the charset is ISO-8859-1 and SHOULD do so when parameter even when the charset is ISO-8859-1 and SHOULD do so when
it is known that it will not confuse the recipient. it is known that it will not confuse the recipient.
Unfortunately, some older HTTP/1.0 clients did not deal properly with Unfortunately, some older HTTP/1.0 clients did not deal properly with
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indicates what decoding mechanism will be required to remove the indicates what decoding mechanism will be required to remove the
encoding. encoding.
The Internet Assigned Numbers Authority (IANA) acts as a registry for The Internet Assigned Numbers Authority (IANA) acts as a registry for
content-coding value tokens. Initially, the registry contains the content-coding value tokens. Initially, the registry contains the
following tokens: following tokens:
gzip gzip
An encoding format produced by the file compression program "gzip" An encoding format produced by the file compression program "gzip"
(GNU zip) as described in RFC 1952 [25]. This format is a Lempel- (GNU zip) as described in [RFC1952]. This format is a Lempel-Ziv
Ziv coding (LZ77) with a 32 bit CRC. coding (LZ77) with a 32 bit CRC.
compress compress
The encoding format produced by the common UNIX file compression The encoding format produced by the common UNIX file compression
program "compress". This format is an adaptive Lempel-Ziv-Welch program "compress". This format is an adaptive Lempel-Ziv-Welch
coding (LZW). coding (LZW).
Use of program names for the identification of encoding formats is Use of program names for the identification of encoding formats is
not desirable and is discouraged for future encodings. Their use not desirable and is discouraged for future encodings. Their use
here is representative of historical practice, not good design. here is representative of historical practice, not good design.
For compatibility with previous implementations of HTTP, For compatibility with previous implementations of HTTP,
applications SHOULD consider "x-gzip" and "x-compress" to be applications SHOULD consider "x-gzip" and "x-compress" to be
equivalent to "gzip" and "compress" respectively. equivalent to "gzip" and "compress" respectively.
deflate deflate
The "zlib" format defined in RFC 1950 [31] in combination with the The "zlib" format defined in [RFC1950] in combination with the
"deflate" compression mechanism described in RFC 1951 [29]. "deflate" compression mechanism described in [RFC1951].
identity identity
The default (identity) encoding; the use of no transformation The default (identity) encoding; the use of no transformation
whatsoever. This content-coding is used only in the Accept- whatsoever. This content-coding is used only in the Accept-
Encoding header, and SHOULD NOT be used in the Content-Encoding Encoding header, and SHOULD NOT be used in the Content-Encoding
header. header.
New content-coding value tokens SHOULD be registered; to allow New content-coding value tokens SHOULD be registered; to allow
interoperability between clients and servers, specifications of the interoperability between clients and servers, specifications of the
content coding algorithms needed to implement a new value SHOULD be content coding algorithms needed to implement a new value SHOULD be
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Whenever a transfer-coding is applied to a message-body, the set of Whenever a transfer-coding is applied to a message-body, the set of
transfer-codings MUST include "chunked", unless the message is transfer-codings MUST include "chunked", unless the message is
terminated by closing the connection. When the "chunked" transfer- terminated by closing the connection. When the "chunked" transfer-
coding is used, it MUST be the last transfer-coding applied to the coding is used, it MUST be the last transfer-coding applied to the
message-body. The "chunked" transfer-coding MUST NOT be applied more message-body. The "chunked" transfer-coding MUST NOT be applied more
than once to a message-body. These rules allow the recipient to than once to a message-body. These rules allow the recipient to
determine the transfer-length of the message (Section 4.4). determine the transfer-length of the message (Section 4.4).
Transfer-codings are analogous to the Content-Transfer-Encoding Transfer-codings are analogous to the Content-Transfer-Encoding
values of MIME [7], which were designed to enable safe transport of values of MIME [RFC2045], which were designed to enable safe
binary data over a 7-bit transport service. However, safe transport transport of binary data over a 7-bit transport service. However,
has a different focus for an 8bit-clean transfer protocol. In HTTP, safe transport has a different focus for an 8bit-clean transfer
the only unsafe characteristic of message-bodies is the difficulty in protocol. In HTTP, the only unsafe characteristic of message-bodies
determining the exact body length (Section 7.2.2), or the desire to is the difficulty in determining the exact body length
encrypt data over a shared transport. (Section 7.2.2), or the desire to encrypt data over a shared
transport.
The Internet Assigned Numbers Authority (IANA) acts as a registry for The Internet Assigned Numbers Authority (IANA) acts as a registry for
transfer-coding value tokens. Initially, the registry contains the transfer-coding value tokens. Initially, the registry contains the
following tokens: "chunked" (Section 3.6.1), "gzip" (Section 3.5), following tokens: "chunked" (Section 3.6.1), "gzip" (Section 3.5),
"compress" (Section 3.5), and "deflate" (Section 3.5). "compress" (Section 3.5), and "deflate" (Section 3.5).
New transfer-coding value tokens SHOULD be registered in the same way New transfer-coding value tokens SHOULD be registered in the same way
as new content-coding value tokens (Section 3.5). as new content-coding value tokens (Section 3.5).
A server which receives an entity-body with a transfer-coding it does A server which receives an entity-body with a transfer-coding it does
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An example process for decoding a Chunked-Body is presented in An example process for decoding a Chunked-Body is presented in
Appendix D.6. Appendix D.6.
All HTTP/1.1 applications MUST be able to receive and decode the All HTTP/1.1 applications MUST be able to receive and decode the
"chunked" transfer-coding, and MUST ignore chunk-extension extensions "chunked" transfer-coding, and MUST ignore chunk-extension extensions
they do not understand. they do not understand.
3.7. Media Types 3.7. Media Types
HTTP uses Internet Media Types [17] in the Content-Type HTTP uses Internet Media Types [RFC1590] in the Content-Type
(Section 14.17) and Accept (Section 14.1) header fields in order to (Section 14.17) and Accept (Section 14.1) header fields in order to
provide open and extensible data typing and type negotiation. provide open and extensible data typing and type negotiation.
media-type = type "/" subtype *( ";" parameter ) media-type = type "/" subtype *( ";" parameter )
type = token type = token
subtype = token subtype = token
Parameters MAY follow the type/subtype in the form of attribute/value Parameters MAY follow the type/subtype in the form of attribute/value
pairs (as defined in Section 3.6). pairs (as defined in Section 3.6).
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attribute and its value. The presence or absence of a parameter attribute and its value. The presence or absence of a parameter
might be significant to the processing of a media-type, depending on might be significant to the processing of a media-type, depending on
its definition within the media type registry. its definition within the media type registry.
Note that some older HTTP applications do not recognize media type Note that some older HTTP applications do not recognize media type
parameters. When sending data to older HTTP applications, parameters. When sending data to older HTTP applications,
implementations SHOULD only use media type parameters when they are implementations SHOULD only use media type parameters when they are
required by that type/subtype definition. required by that type/subtype definition.
Media-type values are registered with the Internet Assigned Number Media-type values are registered with the Internet Assigned Number
Authority (IANA [19]). The media type registration process is Authority (IANA [RFC1700]). The media type registration process is
outlined in RFC 1590 [17]. Use of non-registered media types is outlined in [RFC1590]. Use of non-registered media types is
discouraged. discouraged.
3.7.1. Canonicalization and Text Defaults 3.7.1. Canonicalization and Text Defaults
Internet media types are registered with a canonical form. An Internet media types are registered with a canonical form. An
entity-body transferred via HTTP messages MUST be represented in the entity-body transferred via HTTP messages MUST be represented in the
appropriate canonical form prior to its transmission except for appropriate canonical form prior to its transmission except for
"text" types, as defined in the next paragraph. "text" types, as defined in the next paragraph.
When in canonical form, media subtypes of the "text" type use CRLF as When in canonical form, media subtypes of the "text" type use CRLF as
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parameter is provided by the sender, media subtypes of the "text" parameter is provided by the sender, media subtypes of the "text"
type are defined to have a default charset value of "ISO-8859-1" when type are defined to have a default charset value of "ISO-8859-1" when
received via HTTP. Data in character sets other than "ISO-8859-1" or received via HTTP. Data in character sets other than "ISO-8859-1" or
its subsets MUST be labeled with an appropriate charset value. See its subsets MUST be labeled with an appropriate charset value. See
Section 3.4.1 for compatibility problems. Section 3.4.1 for compatibility problems.
3.7.2. Multipart Types 3.7.2. Multipart Types
MIME provides for a number of "multipart" types -- encapsulations of MIME provides for a number of "multipart" types -- encapsulations of
one or more entities within a single message-body. All multipart one or more entities within a single message-body. All multipart
types share a common syntax, as defined in section 5.1.1 of RFC 2046 types share a common syntax, as defined in Section 5.1.1 of
[40], and MUST include a boundary parameter as part of the media type [RFC2046], and MUST include a boundary parameter as part of the media
value. The message body is itself a protocol element and MUST type value. The message body is itself a protocol element and MUST
therefore use only CRLF to represent line breaks between body-parts. therefore use only CRLF to represent line breaks between body-parts.
Unlike in RFC 2046, the epilogue of any multipart message MUST be Unlike in RFC 2046, the epilogue of any multipart message MUST be
empty; HTTP applications MUST NOT transmit the epilogue (even if the empty; HTTP applications MUST NOT transmit the epilogue (even if the
original multipart contains an epilogue). These restrictions exist original multipart contains an epilogue). These restrictions exist
in order to preserve the self-delimiting nature of a multipart in order to preserve the self-delimiting nature of a multipart
message-body, wherein the "end" of the message-body is indicated by message-body, wherein the "end" of the message-body is indicated by
the ending multipart boundary. the ending multipart boundary.
In general, HTTP treats a multipart message-body no differently than In general, HTTP treats a multipart message-body no differently than
any other media type: strictly as payload. The one exception is the any other media type: strictly as payload. The one exception is the
"multipart/byteranges" type (Appendix B) when it appears in a 206 "multipart/byteranges" type (Appendix B) when it appears in a 206
(Partial Content) response, which will be interpreted by some HTTP (Partial Content) response, which will be interpreted by some HTTP
caching mechanisms as described in sections 13.5.4 and 14.16. In all caching mechanisms as described in Sections 13.5.4 and 14.16. In all
other cases, an HTTP user agent SHOULD follow the same or similar other cases, an HTTP user agent SHOULD follow the same or similar
behavior as a MIME user agent would upon receipt of a multipart type. behavior as a MIME user agent would upon receipt of a multipart type.
The MIME header fields within each body-part of a multipart message- The MIME header fields within each body-part of a multipart message-
body do not have any significance to HTTP beyond that defined by body do not have any significance to HTTP beyond that defined by
their MIME semantics. their MIME semantics.
In general, an HTTP user agent SHOULD follow the same or similar In general, an HTTP user agent SHOULD follow the same or similar
behavior as a MIME user agent would upon receipt of a multipart type. behavior as a MIME user agent would upon receipt of a multipart type.
If an application receives an unrecognized multipart subtype, the If an application receives an unrecognized multipart subtype, the
application MUST treat it as being equivalent to "multipart/mixed". application MUST treat it as being equivalent to "multipart/mixed".
Note: The "multipart/form-data" type has been specifically defined Note: The "multipart/form-data" type has been specifically defined
for carrying form data suitable for processing via the POST for carrying form data suitable for processing via the POST
request method, as described in RFC 1867 [15]. request method, as described in [RFC1867].
3.8. Product Tokens 3.8. Product Tokens
Product tokens are used to allow communicating applications to Product tokens are used to allow communicating applications to
identify themselves by software name and version. Most fields using identify themselves by software name and version. Most fields using
product tokens also allow sub-products which form a significant part product tokens also allow sub-products which form a significant part
of the application to be listed, separated by white space. By of the application to be listed, separated by white space. By
convention, the products are listed in order of their significance convention, the products are listed in order of their significance
for identifying the application. for identifying the application.
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3.10. Language Tags 3.10. Language Tags
A language tag identifies a natural language spoken, written, or A language tag identifies a natural language spoken, written, or
otherwise conveyed by human beings for communication of information otherwise conveyed by human beings for communication of information
to other human beings. Computer languages are explicitly excluded. to other human beings. Computer languages are explicitly excluded.
HTTP uses language tags within the Accept-Language and Content- HTTP uses language tags within the Accept-Language and Content-
Language fields. Language fields.
The syntax and registry of HTTP language tags is the same as that The syntax and registry of HTTP language tags is the same as that
defined by RFC 1766 [1]. In summary, a language tag is composed of 1 defined by [RFC1766]. In summary, a language tag is composed of 1 or
or more parts: A primary language tag and a possibly empty series of more parts: A primary language tag and a possibly empty series of
subtags: subtags:
language-tag = primary-tag *( "-" subtag ) language-tag = primary-tag *( "-" subtag )
primary-tag = 1*8ALPHA primary-tag = 1*8ALPHA
subtag = 1*8ALPHA subtag = 1*8ALPHA
White space is not allowed within the tag and all tags are case- White space is not allowed within the tag and all tags are case-
insensitive. The name space of language tags is administered by the insensitive. The name space of language tags is administered by the
IANA. Example tags include: IANA. Example tags include:
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4. HTTP Message 4. HTTP Message
4.1. Message Types 4.1. Message Types
HTTP messages consist of requests from client to server and responses HTTP messages consist of requests from client to server and responses
from server to client. from server to client.
HTTP-message = Request | Response ; HTTP/1.1 messages HTTP-message = Request | Response ; HTTP/1.1 messages
Request (Section 5) and Response (Section 6) messages use the generic Request (Section 5) and Response (Section 6) messages use the generic
message format of RFC 822 [9] for transferring entities (the payload message format of [RFC822] for transferring entities (the payload of
of the message). Both types of message consist of a start-line, zero the message). Both types of message consist of a start-line, zero or
or more header fields (also known as "headers"), an empty line (i.e., more header fields (also known as "headers"), an empty line (i.e., a
a line with nothing preceding the CRLF) indicating the end of the line with nothing preceding the CRLF) indicating the end of the
header fields, and possibly a message-body. header fields, and possibly a message-body.
generic-message = start-line generic-message = start-line
*(message-header CRLF) *(message-header CRLF)
CRLF CRLF
[ message-body ] [ message-body ]
start-line = Request-Line | Status-Line start-line = Request-Line | Status-Line
In the interest of robustness, servers SHOULD ignore any empty In the interest of robustness, servers SHOULD ignore any empty
line(s) received where a Request-Line is expected. In other words, line(s) received where a Request-Line is expected. In other words,
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Certain buggy HTTP/1.0 client implementations generate extra CRLF's Certain buggy HTTP/1.0 client implementations generate extra CRLF's
after a POST request. To restate what is explicitly forbidden by the after a POST request. To restate what is explicitly forbidden by the
BNF, an HTTP/1.1 client MUST NOT preface or follow a request with an BNF, an HTTP/1.1 client MUST NOT preface or follow a request with an
extra CRLF. extra CRLF.
4.2. Message Headers 4.2. Message Headers
HTTP header fields, which include general-header (Section 4.5), HTTP header fields, which include general-header (Section 4.5),
request-header (Section 5.3), response-header (Section 6.2), and request-header (Section 5.3), response-header (Section 6.2), and
entity-header (Section 7.1) fields, follow the same generic format as entity-header (Section 7.1) fields, follow the same generic format as
that given in Section 3.1 of RFC 822 [9]. Each header field consists that given in Section 3.1 of [RFC822]. Each header field consists of
of a name followed by a colon (":") and the field value. Field names a name followed by a colon (":") and the field value. Field names
are case-insensitive. The field value MAY be preceded by any amount are case-insensitive. The field value MAY be preceded by any amount
of LWS, though a single SP is preferred. Header fields can be of LWS, though a single SP is preferred. Header fields can be
extended over multiple lines by preceding each extra line with at extended over multiple lines by preceding each extra line with at
least one SP or HT. Applications ought to follow "common form", least one SP or HT. Applications ought to follow "common form",
where one is known or indicated, when generating HTTP constructs, where one is known or indicated, when generating HTTP constructs,
since there might exist some implementations that fail to accept since there might exist some implementations that fail to accept
anything beyond the common forms. anything beyond the common forms.
message-header = field-name ":" [ field-value ] message-header = field-name ":" [ field-value ]
field-name = token field-name = token
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GET /pub/WWW/TheProject.html HTTP/1.1 GET /pub/WWW/TheProject.html HTTP/1.1
Host: www.example.org Host: www.example.org
followed by the remainder of the Request. Note that the absolute followed by the remainder of the Request. Note that the absolute
path cannot be empty; if none is present in the original URI, it MUST path cannot be empty; if none is present in the original URI, it MUST
be given as "/" (the server root). be given as "/" (the server root).
The Request-URI is transmitted in the format specified in The Request-URI is transmitted in the format specified in
Section 3.2.1. If the Request-URI is encoded using the "% HEX HEX" Section 3.2.1. If the Request-URI is encoded using the "% HEX HEX"
encoding [42], the origin server MUST decode the Request-URI in order encoding [RFC2396], the origin server MUST decode the Request-URI in
to properly interpret the request. Servers SHOULD respond to invalid order to properly interpret the request. Servers SHOULD respond to
Request-URIs with an appropriate status code. invalid Request-URIs with an appropriate status code.
A transparent proxy MUST NOT rewrite the "abs_path" part of the A transparent proxy MUST NOT rewrite the "abs_path" part of the
received Request-URI when forwarding it to the next inbound server, received Request-URI when forwarding it to the next inbound server,
except as noted above to replace a null abs_path with "/". except as noted above to replace a null abs_path with "/".
Note: The "no rewrite" rule prevents the proxy from changing the Note: The "no rewrite" rule prevents the proxy from changing the
meaning of the request when the origin server is improperly using meaning of the request when the origin server is improperly using
a non-reserved URI character for a reserved purpose. Implementors a non-reserved URI character for a reserved purpose. Implementors
should be aware that some pre-HTTP/1.1 proxies have been known to should be aware that some pre-HTTP/1.1 proxies have been known to
rewrite the Request-URI. rewrite the Request-URI.
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8.1. Persistent Connections 8.1. Persistent Connections
8.1.1. Purpose 8.1.1. Purpose
Prior to persistent connections, a separate TCP connection was Prior to persistent connections, a separate TCP connection was
established to fetch each URL, increasing the load on HTTP servers established to fetch each URL, increasing the load on HTTP servers
and causing congestion on the Internet. The use of inline images and and causing congestion on the Internet. The use of inline images and
other associated data often require a client to make multiple other associated data often require a client to make multiple
requests of the same server in a short amount of time. Analysis of requests of the same server in a short amount of time. Analysis of
these performance problems and results from a prototype these performance problems and results from a prototype
implementation are available [26] [30]. Implementation experience implementation are available [Pad1995] [Spero]. Implementation
and measurements of actual HTTP/1.1 (RFC 2068) implementations show experience and measurements of actual HTTP/1.1 (RFC 2068)
good results [39]. Alternatives have also been explored, for implementations show good results [Nie1997]. Alternatives have also
example, T/TCP [27]. been explored, for example, T/TCP [Tou1998].
Persistent HTTP connections have a number of advantages: Persistent HTTP connections have a number of advantages:
o By opening and closing fewer TCP connections, CPU time is saved in o By opening and closing fewer TCP connections, CPU time is saved in
routers and hosts (clients, servers, proxies, gateways, tunnels, routers and hosts (clients, servers, proxies, gateways, tunnels,
or caches), and memory used for TCP protocol control blocks can be or caches), and memory used for TCP protocol control blocks can be
saved in hosts. saved in hosts.
o HTTP requests and responses can be pipelined on a connection. o HTTP requests and responses can be pipelined on a connection.
Pipelining allows a client to make multiple requests without Pipelining allows a client to make multiple requests without
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It is especially important that proxies correctly implement the It is especially important that proxies correctly implement the
properties of the Connection header field as specified in properties of the Connection header field as specified in
Section 14.10. Section 14.10.
The proxy server MUST signal persistent connections separately with The proxy server MUST signal persistent connections separately with
its clients and the origin servers (or other proxy servers) that it its clients and the origin servers (or other proxy servers) that it
connects to. Each persistent connection applies to only one connects to. Each persistent connection applies to only one
transport link. transport link.
A proxy server MUST NOT establish a HTTP/1.1 persistent connection A proxy server MUST NOT establish a HTTP/1.1 persistent connection
with an HTTP/1.0 client (but see RFC 2068 [33] for information and with an HTTP/1.0 client (but see [RFC2068] for information and
discussion of the problems with the Keep-Alive header implemented by discussion of the problems with the Keep-Alive header implemented by
many HTTP/1.0 clients). many HTTP/1.0 clients).
8.1.4. Practical Considerations 8.1.4. Practical Considerations
Servers will usually have some time-out value beyond which they will Servers will usually have some time-out value beyond which they will
no longer maintain an inactive connection. Proxy servers might make no longer maintain an inactive connection. Proxy servers might make
this a higher value since it is likely that the client will be making this a higher value since it is likely that the client will be making
more connections through the same server. The use of persistent more connections through the same server. The use of persistent
connections places no requirements on the length (or existence) of connections places no requirements on the length (or existence) of
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proxies forwarding messages in an infinite loop. proxies forwarding messages in an infinite loop.
If the request is valid, the response SHOULD contain the entire If the request is valid, the response SHOULD contain the entire
request message in the entity-body, with a Content-Type of "message/ request message in the entity-body, with a Content-Type of "message/
http". Responses to this method MUST NOT be cached. http". Responses to this method MUST NOT be cached.
9.9. CONNECT 9.9. CONNECT
This specification reserves the method name CONNECT for use with a This specification reserves the method name CONNECT for use with a
proxy that can dynamically switch to being a tunnel (e.g. SSL proxy that can dynamically switch to being a tunnel (e.g. SSL
tunneling [44]). tunneling [Luo1998]).
10. Status Code Definitions 10. Status Code Definitions
Each Status-Code is described below, including a description of which Each Status-Code is described below, including a description of which
method(s) it can follow and any metainformation required in the method(s) it can follow and any metainformation required in the
response. response.
10.1. Informational 1xx 10.1. Informational 1xx
This class of status code indicates a provisional response, This class of status code indicates a provisional response,
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respond with this status code. The 304 response MUST NOT contain a respond with this status code. The 304 response MUST NOT contain a
message-body, and thus is always terminated by the first empty line message-body, and thus is always terminated by the first empty line
after the header fields. after the header fields.
The response MUST include the following header fields: The response MUST include the following header fields:
o Date, unless its omission is required by Section 14.18.1 o Date, unless its omission is required by Section 14.18.1
If a clockless origin server obeys these rules, and proxies and If a clockless origin server obeys these rules, and proxies and
clients add their own Date to any response received without one (as clients add their own Date to any response received without one (as
already specified by [RFC 2068], section 14.19), caches will operate already specified by [RFC2068], Section 14.19), caches will operate
correctly. correctly.
o ETag and/or Content-Location, if the header would have been sent o ETag and/or Content-Location, if the header would have been sent
in a 200 response to the same request in a 200 response to the same request
o Expires, Cache-Control, and/or Vary, if the field-value might o Expires, Cache-Control, and/or Vary, if the field-value might
differ from that sent in any previous response for the same differ from that sent in any previous response for the same
variant variant
If the conditional GET used a strong cache validator (see If the conditional GET used a strong cache validator (see
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challenge applicable to the requested resource. The client MAY challenge applicable to the requested resource. The client MAY
repeat the request with a suitable Authorization header field repeat the request with a suitable Authorization header field
(Section 14.8). If the request already included Authorization (Section 14.8). If the request already included Authorization
credentials, then the 401 response indicates that authorization has credentials, then the 401 response indicates that authorization has
been refused for those credentials. If the 401 response contains the been refused for those credentials. If the 401 response contains the
same challenge as the prior response, and the user agent has already same challenge as the prior response, and the user agent has already
attempted authentication at least once, then the user SHOULD be attempted authentication at least once, then the user SHOULD be
presented the entity that was given in the response, since that presented the entity that was given in the response, since that
entity might include relevant diagnostic information. HTTP access entity might include relevant diagnostic information. HTTP access
authentication is explained in "HTTP Authentication: Basic and Digest authentication is explained in "HTTP Authentication: Basic and Digest
Access Authentication" [43]. Access Authentication" [RFC2617].
10.4.3. 402 Payment Required 10.4.3. 402 Payment Required
This code is reserved for future use. This code is reserved for future use.
10.4.4. 403 Forbidden 10.4.4. 403 Forbidden
The server understood the request, but is refusing to fulfill it. The server understood the request, but is refusing to fulfill it.
Authorization will not help and the request SHOULD NOT be repeated. Authorization will not help and the request SHOULD NOT be repeated.
If the request method was not HEAD and the server wishes to make If the request method was not HEAD and the server wishes to make
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10.4.8. 407 Proxy Authentication Required 10.4.8. 407 Proxy Authentication Required
This code is similar to 401 (Unauthorized), but indicates that the This code is similar to 401 (Unauthorized), but indicates that the
client must first authenticate itself with the proxy. The proxy MUST client must first authenticate itself with the proxy. The proxy MUST
return a Proxy-Authenticate header field (Section 14.33) containing a return a Proxy-Authenticate header field (Section 14.33) containing a
challenge applicable to the proxy for the requested resource. The challenge applicable to the proxy for the requested resource. The
client MAY repeat the request with a suitable Proxy-Authorization client MAY repeat the request with a suitable Proxy-Authorization
header field (Section 14.34). HTTP access authentication is header field (Section 14.34). HTTP access authentication is
explained in "HTTP Authentication: Basic and Digest Access explained in "HTTP Authentication: Basic and Digest Access
Authentication" [43]. Authentication" [RFC2617].
10.4.9. 408 Request Timeout 10.4.9. 408 Request Timeout
The client did not produce a request within the time that the server The client did not produce a request within the time that the server
was prepared to wait. The client MAY repeat the request without was prepared to wait. The client MAY repeat the request without
modifications at any later time. modifications at any later time.
10.4.10. 409 Conflict 10.4.10. 409 Conflict
The request could not be completed due to a conflict with the current The request could not be completed due to a conflict with the current
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contain an entity describing why that version is not supported and contain an entity describing why that version is not supported and
what other protocols are supported by that server. what other protocols are supported by that server.
11. Access Authentication 11. Access Authentication
HTTP provides several OPTIONAL challenge-response authentication HTTP provides several OPTIONAL challenge-response authentication
mechanisms which can be used by a server to challenge a client mechanisms which can be used by a server to challenge a client
request and by a client to provide authentication information. The request and by a client to provide authentication information. The
general framework for access authentication, and the specification of general framework for access authentication, and the specification of
"basic" and "digest" authentication, are specified in "HTTP "basic" and "digest" authentication, are specified in "HTTP
Authentication: Basic and Digest Access Authentication" [43]. This Authentication: Basic and Digest Access Authentication" [RFC2617].
specification adopts the definitions of "challenge" and "credentials" This specification adopts the definitions of "challenge" and
from that specification. "credentials" from that specification.
12. Content Negotiation 12. Content Negotiation
Most HTTP responses include an entity which contains information for Most HTTP responses include an entity which contains information for
interpretation by a human user. Naturally, it is desirable to supply interpretation by a human user. Naturally, it is desirable to supply
the user with the "best available" entity corresponding to the the user with the "best available" entity corresponding to the
request. Unfortunately for servers and caches, not all users have request. Unfortunately for servers and caches, not all users have
the same preferences for what is "best," and not all user agents are the same preferences for what is "best," and not all user agents are
equally capable of rendering all entity types. For that reason, HTTP equally capable of rendering all entity types. For that reason, HTTP
has provisions for several mechanisms for "content negotiation" -- has provisions for several mechanisms for "content negotiation" --
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ought to err on the side of maintaining transparency unless a ought to err on the side of maintaining transparency unless a
careful and complete analysis shows significant benefits in careful and complete analysis shows significant benefits in
breaking transparency. breaking transparency.
13.1. 13.1.
13.1.1. Cache Correctness 13.1.1. Cache Correctness
A correct cache MUST respond to a request with the most up-to-date A correct cache MUST respond to a request with the most up-to-date
response held by the cache that is appropriate to the request (see response held by the cache that is appropriate to the request (see
sections 13.2.5, 13.2.6, and 13.12) which meets one of the following Sections 13.2.5, 13.2.6, and 13.12) which meets one of the following
conditions: conditions:
1. It has been checked for equivalence with what the origin server 1. It has been checked for equivalence with what the origin server
would have returned by revalidating the response with the origin would have returned by revalidating the response with the origin
server (Section 13.3); server (Section 13.3);
2. It is "fresh enough" (see Section 13.2). In the default case, 2. It is "fresh enough" (see Section 13.2). In the default case,
this means it meets the least restrictive freshness requirement this means it meets the least restrictive freshness requirement
of the client, origin server, and cache (see Section 14.9); if of the client, origin server, and cache (see Section 14.9); if
the origin server so specifies, it is the freshness requirement the origin server so specifies, it is the freshness requirement
of the origin server alone. If a stored response is not "fresh of the origin server alone. If a stored response is not "fresh
enough" by the most restrictive freshness requirement of both the enough" by the most restrictive freshness requirement of both the
client and the origin server, in carefully considered client and the origin server, in carefully considered
circumstances the cache MAY still return the response with the circumstances the cache MAY still return the response with the
appropriate Warning header (see section 13.1.5 and 14.46), unless appropriate Warning header (see Section 13.1.5 and 14.46), unless
such a response is prohibited (e.g., by a "no-store" cache- such a response is prohibited (e.g., by a "no-store" cache-
directive, or by a "no-cache" cache-request-directive; see directive, or by a "no-cache" cache-request-directive; see
Section 14.9). Section 14.9).
3. It is an appropriate 304 (Not Modified), 305 (Proxy Redirect), or 3. It is an appropriate 304 (Not Modified), 305 (Proxy Redirect), or
error (4xx or 5xx) response message. error (4xx or 5xx) response message.
If the cache can not communicate with the origin server, then a If the cache can not communicate with the origin server, then a
correct cache SHOULD respond as above if the response can be correct cache SHOULD respond as above if the response can be
correctly served from the cache; if not it MUST return an error or correctly served from the cache; if not it MUST return an error or
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13.2.3. Age Calculations 13.2.3. Age Calculations
In order to know if a cached entry is fresh, a cache needs to know if In order to know if a cached entry is fresh, a cache needs to know if
its age exceeds its freshness lifetime. We discuss how to calculate its age exceeds its freshness lifetime. We discuss how to calculate
the latter in Section 13.2.4; this section describes how to calculate the latter in Section 13.2.4; this section describes how to calculate
the age of a response or cache entry. the age of a response or cache entry.
In this discussion, we use the term "now" to mean "the current value In this discussion, we use the term "now" to mean "the current value
of the clock at the host performing the calculation." Hosts that use of the clock at the host performing the calculation." Hosts that use
HTTP, but especially hosts running origin servers and caches, SHOULD HTTP, but especially hosts running origin servers and caches, SHOULD
use NTP [28] or some similar protocol to synchronize their clocks to use NTP [RFC1305] or some similar protocol to synchronize their
a globally accurate time standard. clocks to a globally accurate time standard.
HTTP/1.1 requires origin servers to send a Date header, if possible, HTTP/1.1 requires origin servers to send a Date header, if possible,
with every response, giving the time at which the response was with every response, giving the time at which the response was
generated (see Section 14.18). We use the term "date_value" to generated (see Section 14.18). We use the term "date_value" to
denote the value of the Date header, in a form appropriate for denote the value of the Date header, in a form appropriate for
arithmetic operations. arithmetic operations.
HTTP/1.1 uses the Age response-header to convey the estimated age of HTTP/1.1 uses the Age response-header to convey the estimated age of
the response message when obtained from a cache. The Age field value the response message when obtained from a cache. The Age field value
is the cache's estimate of the amount of time since the response was is the cache's estimate of the amount of time since the response was
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13.3.2. Entity Tag Cache Validators 13.3.2. Entity Tag Cache Validators
The ETag response-header field value, an entity tag, provides for an The ETag response-header field value, an entity tag, provides for an
"opaque" cache validator. This might allow more reliable validation "opaque" cache validator. This might allow more reliable validation
in situations where it is inconvenient to store modification dates, in situations where it is inconvenient to store modification dates,
where the one-second resolution of HTTP date values is not where the one-second resolution of HTTP date values is not
sufficient, or where the origin server wishes to avoid certain sufficient, or where the origin server wishes to avoid certain
paradoxes that might arise from the use of modification dates. paradoxes that might arise from the use of modification dates.
Entity Tags are described in Section 3.11. The headers used with Entity Tags are described in Section 3.11. The headers used with
entity tags are described in sections 14.19, 14.24, 14.26 and 14.44. entity tags are described in Sections 14.19, 14.24, 14.26 and 14.44.
13.3.3. Weak and Strong Validators 13.3.3. Weak and Strong Validators
Since both origin servers and caches will compare two validators to Since both origin servers and caches will compare two validators to
decide if they represent the same or different entities, one normally decide if they represent the same or different entities, one normally
would expect that if the entity (the entity-body or any entity- would expect that if the entity (the entity-body or any entity-
headers) changes in any way, then the associated validator would headers) changes in any way, then the associated validator would
change as well. If this is true, then we call this validator a change as well. If this is true, then we call this validator a
"strong validator." "strong validator."
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Warning: unnecessary modification of end-to-end headers might Warning: unnecessary modification of end-to-end headers might
cause authentication failures if stronger authentication cause authentication failures if stronger authentication
mechanisms are introduced in later versions of HTTP. Such mechanisms are introduced in later versions of HTTP. Such
authentication mechanisms MAY rely on the values of header fields authentication mechanisms MAY rely on the values of header fields
not listed here. not listed here.
The Content-Length field of a request or response is added or deleted The Content-Length field of a request or response is added or deleted
according to the rules in Section 4.4. A transparent proxy MUST according to the rules in Section 4.4. A transparent proxy MUST
preserve the entity-length (Section 7.2.2) of the entity-body, preserve the entity-length (Section 7.2.2) of the entity-body,
although it MAY change the transfer-length (section Section 4.4). although it MAY change the transfer-length (Section 4.4).
13.5.3. Combining Headers 13.5.3. Combining Headers
When a cache makes a validating request to a server, and the server When a cache makes a validating request to a server, and the server
provides a 304 (Not Modified) response or a 206 (Partial Content) provides a 304 (Not Modified) response or a 206 (Partial Content)
response, the cache then constructs a response to send to the response, the cache then constructs a response to send to the
requesting client. requesting client.
If the status code is 304 (Not Modified), the cache uses the entity- If the status code is 304 (Not Modified), the cache uses the entity-
body stored in the cache entry as the entity-body of this outgoing body stored in the cache entry as the entity-body of this outgoing
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prevent a proxy cache from sending a 100 (Continue) response before prevent a proxy cache from sending a 100 (Continue) response before
the inbound server has sent its final reply. the inbound server has sent its final reply.
The alternative (known as "write-back" or "copy-back" caching) is not The alternative (known as "write-back" or "copy-back" caching) is not
allowed in HTTP/1.1, due to the difficulty of providing consistent allowed in HTTP/1.1, due to the difficulty of providing consistent
updates and the problems arising from server, cache, or network updates and the problems arising from server, cache, or network
failure prior to write-back. failure prior to write-back.
13.12. Cache Replacement 13.12. Cache Replacement
If a new cacheable (see sections 14.9.2, 13.2.5, 13.2.6 and 13.8) If a new cacheable (see Sections 14.9.2, 13.2.5, 13.2.6 and 13.8)
response is received from a resource while any existing responses for response is received from a resource while any existing responses for
the same resource are cached, the cache SHOULD use the new response the same resource are cached, the cache SHOULD use the new response
to reply to the current request. It MAY insert it into cache storage to reply to the current request. It MAY insert it into cache storage
and MAY, if it meets all other requirements, use it to respond to any and MAY, if it meets all other requirements, use it to respond to any
future requests that would previously have caused the old response to future requests that would previously have caused the old response to
be returned. If it inserts the new response into cache storage the be returned. If it inserts the new response into cache storage the
rules in Section 13.5.3 apply. rules in Section 13.5.3 apply.
Note: a new response that has an older Date header value than Note: a new response that has an older Date header value than
existing cached responses is not cacheable. existing cached responses is not cacheable.
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agent or client. agent or client.
Note: Most HTTP/1.0 applications do not recognize or obey qvalues Note: Most HTTP/1.0 applications do not recognize or obey qvalues
associated with content-codings. This means that qvalues will not associated with content-codings. This means that qvalues will not
work and are not permitted with x-gzip or x-compress. work and are not permitted with x-gzip or x-compress.
14.4. Accept-Language 14.4. Accept-Language
The Accept-Language request-header field is similar to Accept, but The Accept-Language request-header field is similar to Accept, but
restricts the set of natural languages that are preferred as a restricts the set of natural languages that are preferred as a
response to the request. Language tags are defined in section response to the request. Language tags are defined in Section 3.10.
Section 3.10.
Accept-Language = "Accept-Language" ":" Accept-Language = "Accept-Language" ":"
1#( language-range [ ";" "q" "=" qvalue ] ) 1#( language-range [ ";" "q" "=" qvalue ] )
language-range = ( ( 1*8ALPHA *( "-" 1*8ALPHA ) ) | "*" ) language-range = ( ( 1*8ALPHA *( "-" 1*8ALPHA ) ) | "*" )
Each language-range MAY be given an associated quality value which Each language-range MAY be given an associated quality value which
represents an estimate of the user's preference for the languages represents an estimate of the user's preference for the languages
specified by that range. The quality value defaults to "q=1". For specified by that range. The quality value defaults to "q=1". For
example, example,
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A user agent that wishes to authenticate itself with a server-- A user agent that wishes to authenticate itself with a server--
usually, but not necessarily, after receiving a 401 response--does so usually, but not necessarily, after receiving a 401 response--does so
by including an Authorization request-header field with the request. by including an Authorization request-header field with the request.
The Authorization field value consists of credentials containing the The Authorization field value consists of credentials containing the
authentication information of the user agent for the realm of the authentication information of the user agent for the realm of the
resource being requested. resource being requested.
Authorization = "Authorization" ":" credentials Authorization = "Authorization" ":" credentials
HTTP access authentication is described in "HTTP Authentication: HTTP access authentication is described in "HTTP Authentication:
Basic and Digest Access Authentication" [43]. If a request is Basic and Digest Access Authentication" [RFC2617]. If a request is
authenticated and a realm specified, the same credentials SHOULD be authenticated and a realm specified, the same credentials SHOULD be
valid for all other requests within this realm (assuming that the valid for all other requests within this realm (assuming that the
authentication scheme itself does not require otherwise, such as authentication scheme itself does not require otherwise, such as
credentials that vary according to a challenge value or using credentials that vary according to a challenge value or using
synchronized clocks). synchronized clocks).
When a shared cache (see Section 13.7) receives a request containing When a shared cache (see Section 13.7) receives a request containing
an Authorization field, it MUST NOT return the corresponding response an Authorization field, it MUST NOT return the corresponding response
as a reply to any other request, unless one of the following specific as a reply to any other request, unless one of the following specific
exceptions holds: exceptions holds:
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Section 13.6. Section 13.6.
If the Content-Location is a relative URI, the relative URI is If the Content-Location is a relative URI, the relative URI is
interpreted relative to the Request-URI. interpreted relative to the Request-URI.
The meaning of the Content-Location header in PUT or POST requests is The meaning of the Content-Location header in PUT or POST requests is
undefined; servers are free to ignore it in those cases. undefined; servers are free to ignore it in those cases.
14.15. Content-MD5 14.15. Content-MD5
The Content-MD5 entity-header field, as defined in RFC 1864 [23], is The Content-MD5 entity-header field, as defined in [RFC1864], is an
an MD5 digest of the entity-body for the purpose of providing an end- MD5 digest of the entity-body for the purpose of providing an end-to-
to-end message integrity check (MIC) of the entity-body. (Note: a end message integrity check (MIC) of the entity-body. (Note: a MIC
MIC is good for detecting accidental modification of the entity-body is good for detecting accidental modification of the entity-body in
in transit, but is not proof against malicious attacks.) transit, but is not proof against malicious attacks.)
Content-MD5 = "Content-MD5" ":" md5-digest Content-MD5 = "Content-MD5" ":" md5-digest
md5-digest = <base64 of 128 bit MD5 digest as per RFC 1864> md5-digest = <base64 of 128 bit MD5 digest as per [RFC1864]>
The Content-MD5 header field MAY be generated by an origin server or The Content-MD5 header field MAY be generated by an origin server or
client to function as an integrity check of the entity-body. Only client to function as an integrity check of the entity-body. Only
origin servers or clients MAY generate the Content-MD5 header field; origin servers or clients MAY generate the Content-MD5 header field;
proxies and gateways MUST NOT generate it, as this would defeat its proxies and gateways MUST NOT generate it, as this would defeat its
value as an end-to-end integrity check. Any recipient of the entity- value as an end-to-end integrity check. Any recipient of the entity-
body, including gateways and proxies, MAY check that the digest value body, including gateways and proxies, MAY check that the digest value
in this header field matches that of the entity-body as received. in this header field matches that of the entity-body as received.
The MD5 digest is computed based on the content of the entity-body, The MD5 digest is computed based on the content of the entity-body,
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Content-Type: text/html; charset=ISO-8859-4 Content-Type: text/html; charset=ISO-8859-4
Further discussion of methods for identifying the media type of an Further discussion of methods for identifying the media type of an
entity is provided in Section 7.2.1. entity is provided in Section 7.2.1.
14.18. Date 14.18. Date
The Date general-header field represents the date and time at which The Date general-header field represents the date and time at which
the message was originated, having the same semantics as orig-date in the message was originated, having the same semantics as orig-date in
RFC 822. The field value is an HTTP-date, as described in RFC 822. The field value is an HTTP-date, as described in
Section 3.3.1; it MUST be sent in RFC 1123 [8]-date format. Section 3.3.1; it MUST be sent in [RFC1123]-date format.
Date = "Date" ":" HTTP-date Date = "Date" ":" HTTP-date
An example is An example is
Date: Tue, 15 Nov 1994 08:12:31 GMT Date: Tue, 15 Nov 1994 08:12:31 GMT
Origin servers MUST include a Date header field in all responses, Origin servers MUST include a Date header field in all responses,
except in these cases: except in these cases:
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3. If the server does not have a clock that can provide a reasonable 3. If the server does not have a clock that can provide a reasonable
approximation of the current time, its responses MUST NOT include approximation of the current time, its responses MUST NOT include
a Date header field. In this case, the rules in Section 14.18.1 a Date header field. In this case, the rules in Section 14.18.1
MUST be followed. MUST be followed.
A received message that does not have a Date header field MUST be A received message that does not have a Date header field MUST be
assigned one by the recipient if the message will be cached by that assigned one by the recipient if the message will be cached by that
recipient or gatewayed via a protocol which requires a Date. An HTTP recipient or gatewayed via a protocol which requires a Date. An HTTP
implementation without a clock MUST NOT cache responses without implementation without a clock MUST NOT cache responses without
revalidating them on every use. An HTTP cache, especially a shared revalidating them on every use. An HTTP cache, especially a shared
cache, SHOULD use a mechanism, such as NTP [28], to synchronize its cache, SHOULD use a mechanism, such as NTP [RFC1305], to synchronize
clock with a reliable external standard. its clock with a reliable external standard.
Clients SHOULD only send a Date header field in messages that include Clients SHOULD only send a Date header field in messages that include
an entity-body, as in the case of the PUT and POST requests, and even an entity-body, as in the case of the PUT and POST requests, and even
then it is optional. A client without a clock MUST NOT send a Date then it is optional. A client without a clock MUST NOT send a Date
header field in a request. header field in a request.
The HTTP-date sent in a Date header SHOULD NOT represent a date and The HTTP-date sent in a Date header SHOULD NOT represent a date and
time subsequent to the generation of the message. It SHOULD time subsequent to the generation of the message. It SHOULD
represent the best available approximation of the date and time of represent the best available approximation of the date and time of
message generation, unless the implementation has no means of message generation, unless the implementation has no means of
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an entity-body, as in the case of the PUT and POST requests, and even an entity-body, as in the case of the PUT and POST requests, and even
then it is optional. A client without a clock MUST NOT send a Date then it is optional. A client without a clock MUST NOT send a Date
header field in a request. header field in a request.
The HTTP-date sent in a Date header SHOULD NOT represent a date and The HTTP-date sent in a Date header SHOULD NOT represent a date and
time subsequent to the generation of the message. It SHOULD time subsequent to the generation of the message. It SHOULD
represent the best available approximation of the date and time of represent the best available approximation of the date and time of
message generation, unless the implementation has no means of message generation, unless the implementation has no means of
generating a reasonably accurate date and time. In theory, the date generating a reasonably accurate date and time. In theory, the date
ought to represent the moment just before the entity is generated. ought to represent the moment just before the entity is generated.
In practice, the date can be generated at any time during the message In practice, the date can be generated at any time during the message
origination without affecting its semantic value. origination without affecting its semantic value.
14.18.1. Clockless Origin Server Operation 14.18.1. Clockless Origin Server Operation
Some origin server implementations might not have a clock available. Some origin server implementations might not have a clock available.
An origin server without a clock MUST NOT assign Expires or Last- An origin server without a clock MUST NOT assign Expires or Last-
Modified values to a response, unless these values were associated Modified values to a response, unless these values were associated
with the resource by a system or user with a reliable clock. It MAY with the resource by a system or user with a reliable clock. It MAY
assign an Expires value that is known, at or before server assign an Expires value that is known, at or before server
configuration time, to be in the past (this allows "pre-expiration" configuration time, to be in the past (this allows "pre-expiration"
of responses without storing separate Expires values for each of responses without storing separate Expires values for each
resource). resource).
14.19. ETag 14.19. ETag
The ETag response-header field provides the current value of the The ETag response-header field provides the current value of the
entity tag for the requested variant. The headers used with entity entity tag for the requested variant. The headers used with entity
tags are described in sections 14.24, 14.26 and 14.44. The entity tags are described in Sections 14.24, 14.26 and 14.44. The entity
tag MAY be used for comparison with other entities from the same tag MAY be used for comparison with other entities from the same
resource (see Section 13.3.3). resource (see Section 13.3.3).
ETag = "ETag" ":" entity-tag ETag = "ETag" ":" entity-tag
Examples: Examples:
ETag: "xyzzy" ETag: "xyzzy"
ETag: W/"xyzzy" ETag: W/"xyzzy"
ETag: "" ETag: ""
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The presence of an Expires header field with a date value of some The presence of an Expires header field with a date value of some
time in the future on a response that otherwise would by default be time in the future on a response that otherwise would by default be
non-cacheable indicates that the response is cacheable, unless non-cacheable indicates that the response is cacheable, unless
indicated otherwise by a Cache-Control header field (Section 14.9). indicated otherwise by a Cache-Control header field (Section 14.9).
14.22. From 14.22. From
The From request-header field, if given, SHOULD contain an Internet The From request-header field, if given, SHOULD contain an Internet
e-mail address for the human user who controls the requesting user e-mail address for the human user who controls the requesting user
agent. The address SHOULD be machine-usable, as defined by "mailbox" agent. The address SHOULD be machine-usable, as defined by "mailbox"
in RFC 822 [9] as updated by RFC 1123 [8]: in [RFC822] as updated by [RFC1123]:
From = "From" ":" mailbox From = "From" ":" mailbox
An example is: An example is:
From: webmaster@w3.org From: webmaster@w3.org
This header field MAY be used for logging purposes and as a means for This header field MAY be used for logging purposes and as a means for
identifying the source of invalid or unwanted requests. It SHOULD identifying the source of invalid or unwanted requests. It SHOULD
NOT be used as an insecure form of access protection. The NOT be used as an insecure form of access protection. The
skipping to change at page 140, line 36 skipping to change at page 139, line 23
A client MUST include a Host header field in all HTTP/1.1 request A client MUST include a Host header field in all HTTP/1.1 request
messages . If the requested URI does not include an Internet host messages . If the requested URI does not include an Internet host
name for the service being requested, then the Host header field MUST name for the service being requested, then the Host header field MUST
be given with an empty value. An HTTP/1.1 proxy MUST ensure that any be given with an empty value. An HTTP/1.1 proxy MUST ensure that any
request message it forwards does contain an appropriate Host header request message it forwards does contain an appropriate Host header
field that identifies the service being requested by the proxy. All field that identifies the service being requested by the proxy. All
Internet-based HTTP/1.1 servers MUST respond with a 400 (Bad Request) Internet-based HTTP/1.1 servers MUST respond with a 400 (Bad Request)
status code to any HTTP/1.1 request message which lacks a Host header status code to any HTTP/1.1 request message which lacks a Host header
field. field.
See sections 5.2 and F.1.1 for other requirements relating to Host. See Sections 5.2 and F.1.1 for other requirements relating to Host.
14.24. If-Match 14.24. If-Match
The If-Match request-header field is used with a method to make it The If-Match request-header field is used with a method to make it
conditional. A client that has one or more entities previously conditional. A client that has one or more entities previously
obtained from the resource can verify that one of those entities is obtained from the resource can verify that one of those entities is
current by including a list of their associated entity tags in the current by including a list of their associated entity tags in the
If-Match header field. Entity tags are defined in Section 3.11. The If-Match header field. Entity tags are defined in Section 3.11. The
purpose of this feature is to allow efficient updates of cached purpose of this feature is to allow efficient updates of cached
information with a minimum amount of transaction overhead. It is information with a minimum amount of transaction overhead. It is
skipping to change at page 148, line 42 skipping to change at page 147, line 30
14.33. Proxy-Authenticate 14.33. Proxy-Authenticate
The Proxy-Authenticate response-header field MUST be included as part The Proxy-Authenticate response-header field MUST be included as part
of a 407 (Proxy Authentication Required) response. The field value of a 407 (Proxy Authentication Required) response. The field value
consists of a challenge that indicates the authentication scheme and consists of a challenge that indicates the authentication scheme and
parameters applicable to the proxy for this Request-URI. parameters applicable to the proxy for this Request-URI.
Proxy-Authenticate = "Proxy-Authenticate" ":" 1#challenge Proxy-Authenticate = "Proxy-Authenticate" ":" 1#challenge
The HTTP access authentication process is described in "HTTP The HTTP access authentication process is described in "HTTP
Authentication: Basic and Digest Access Authentication" [43]. Unlike Authentication: Basic and Digest Access Authentication" [RFC2617].
WWW-Authenticate, the Proxy-Authenticate header field applies only to Unlike WWW-Authenticate, the Proxy-Authenticate header field applies
the current connection and SHOULD NOT be passed on to downstream only to the current connection and SHOULD NOT be passed on to
clients. However, an intermediate proxy might need to obtain its own downstream clients. However, an intermediate proxy might need to
credentials by requesting them from the downstream client, which in obtain its own credentials by requesting them from the downstream
some circumstances will appear as if the proxy is forwarding the client, which in some circumstances will appear as if the proxy is
Proxy-Authenticate header field. forwarding the Proxy-Authenticate header field.
14.34. Proxy-Authorization 14.34. Proxy-Authorization
The Proxy-Authorization request-header field allows the client to The Proxy-Authorization request-header field allows the client to
identify itself (or its user) to a proxy which requires identify itself (or its user) to a proxy which requires
authentication. The Proxy-Authorization field value consists of authentication. The Proxy-Authorization field value consists of
credentials containing the authentication information of the user credentials containing the authentication information of the user
agent for the proxy and/or realm of the resource being requested. agent for the proxy and/or realm of the resource being requested.
Proxy-Authorization = "Proxy-Authorization" ":" credentials Proxy-Authorization = "Proxy-Authorization" ":" credentials
The HTTP access authentication process is described in "HTTP The HTTP access authentication process is described in "HTTP
Authentication: Basic and Digest Access Authentication" [43]. Unlike Authentication: Basic and Digest Access Authentication" [RFC2617].
Authorization, the Proxy-Authorization header field applies only to Unlike Authorization, the Proxy-Authorization header field applies
the next outbound proxy that demanded authentication using the Proxy- only to the next outbound proxy that demanded authentication using
Authenticate field. When multiple proxies are used in a chain, the the Proxy-Authenticate field. When multiple proxies are used in a
Proxy-Authorization header field is consumed by the first outbound chain, the Proxy-Authorization header field is consumed by the first
proxy that was expecting to receive credentials. A proxy MAY relay outbound proxy that was expecting to receive credentials. A proxy
the credentials from the client request to the next proxy if that is MAY relay the credentials from the client request to the next proxy
the mechanism by which the proxies cooperatively authenticate a given if that is the mechanism by which the proxies cooperatively
request. authenticate a given request.
14.35. Range 14.35. Range
14.35.1. Byte Ranges 14.35.1. Byte Ranges
Since all HTTP entities are represented in HTTP messages as sequences Since all HTTP entities are represented in HTTP messages as sequences
of bytes, the concept of a byte range is meaningful for any HTTP of bytes, the concept of a byte range is meaningful for any HTTP
entity. (However, not all clients and servers need to support byte- entity. (However, not all clients and servers need to support byte-
range operations.) range operations.)
skipping to change at page 158, line 6 skipping to change at page 156, line 37
client), play a role in the selection of the response representation. client), play a role in the selection of the response representation.
The "*" value MUST NOT be generated by a proxy server; it may only be The "*" value MUST NOT be generated by a proxy server; it may only be
generated by an origin server. generated by an origin server.
14.45. Via 14.45. Via
The Via general-header field MUST be used by gateways and proxies to The Via general-header field MUST be used by gateways and proxies to
indicate the intermediate protocols and recipients between the user indicate the intermediate protocols and recipients between the user
agent and the server on requests, and between the origin server and agent and the server on requests, and between the origin server and
the client on responses. It is analogous to the "Received" field of the client on responses. It is analogous to the "Received" field of
RFC 822 [9] and is intended to be used for tracking message forwards, [RFC822] and is intended to be used for tracking message forwards,
avoiding request loops, and identifying the protocol capabilities of avoiding request loops, and identifying the protocol capabilities of
all senders along the request/response chain. all senders along the request/response chain.
Via = "Via" ":" 1#( received-protocol received-by [ comment ] ) Via = "Via" ":" 1#( received-protocol received-by [ comment ] )
received-protocol = [ protocol-name "/" ] protocol-version received-protocol = [ protocol-name "/" ] protocol-version
protocol-name = token protocol-name = token
protocol-version = token protocol-version = token
received-by = ( host [ ":" port ] ) | pseudonym received-by = ( host [ ":" port ] ) | pseudonym
pseudonym = token pseudonym = token
skipping to change at page 160, line 12 skipping to change at page 158, line 42
The warn-text SHOULD be in a natural language and character set that The warn-text SHOULD be in a natural language and character set that
is most likely to be intelligible to the human user receiving the is most likely to be intelligible to the human user receiving the
response. This decision MAY be based on any available knowledge, response. This decision MAY be based on any available knowledge,
such as the location of the cache or user, the Accept-Language field such as the location of the cache or user, the Accept-Language field
in a request, the Content-Language field in a response, etc. The in a request, the Content-Language field in a response, etc. The
default language is English and the default character set is ISO- default language is English and the default character set is ISO-
8859-1. 8859-1.
If a character set other than ISO-8859-1 is used, it MUST be encoded If a character set other than ISO-8859-1 is used, it MUST be encoded
in the warn-text using the method described in RFC 2047 [14]. in the warn-text using the method described in [RFC2047].
Warning headers can in general be applied to any message, however Warning headers can in general be applied to any message, however
some specific warn-codes are specific to caches and can only be some specific warn-codes are specific to caches and can only be
applied to response messages. New Warning headers SHOULD be added applied to response messages. New Warning headers SHOULD be added
after any existing Warning headers. A cache MUST NOT delete any after any existing Warning headers. A cache MUST NOT delete any
Warning header that it received with a message. However, if a cache Warning header that it received with a message. However, if a cache
successfully validates a cache entry, it SHOULD remove any Warning successfully validates a cache entry, it SHOULD remove any Warning
headers previously attached to that entry except as specified for headers previously attached to that entry except as specified for
specific Warning codes. It MUST then add any Warning headers specific Warning codes. It MUST then add any Warning headers
received in the validating response. In other words, Warning headers received in the validating response. In other words, Warning headers
skipping to change at page 162, line 17 skipping to change at page 160, line 46
14.47. WWW-Authenticate 14.47. WWW-Authenticate
The WWW-Authenticate response-header field MUST be included in 401 The WWW-Authenticate response-header field MUST be included in 401
(Unauthorized) response messages. The field value consists of at (Unauthorized) response messages. The field value consists of at
least one challenge that indicates the authentication scheme(s) and least one challenge that indicates the authentication scheme(s) and
parameters applicable to the Request-URI. parameters applicable to the Request-URI.
WWW-Authenticate = "WWW-Authenticate" ":" 1#challenge WWW-Authenticate = "WWW-Authenticate" ":" 1#challenge
The HTTP access authentication process is described in "HTTP The HTTP access authentication process is described in "HTTP
Authentication: Basic and Digest Access Authentication" [43]. User Authentication: Basic and Digest Access Authentication" [RFC2617].
agents are advised to take special care in parsing the WWW- User agents are advised to take special care in parsing the WWW-
Authenticate field value as it might contain more than one challenge, Authenticate field value as it might contain more than one challenge,
or if more than one WWW-Authenticate header field is provided, the or if more than one WWW-Authenticate header field is provided, the
contents of a challenge itself can contain a comma-separated list of contents of a challenge itself can contain a comma-separated list of
authentication parameters. authentication parameters.
15. Security Considerations 15. Security Considerations
This section is meant to inform application developers, information This section is meant to inform application developers, information
providers, and users of the security limitations in HTTP/1.1 as providers, and users of the security limitations in HTTP/1.1 as
described by this document. The discussion does not include described by this document. The discussion does not include
skipping to change at page 166, line 33 skipping to change at page 164, line 33
to be cached, however, only when the TTL (Time To Live) information to be cached, however, only when the TTL (Time To Live) information
reported by the name server makes it likely that the cached reported by the name server makes it likely that the cached
information will remain useful. information will remain useful.
If HTTP clients cache the results of host name lookups in order to If HTTP clients cache the results of host name lookups in order to
achieve a performance improvement, they MUST observe the TTL achieve a performance improvement, they MUST observe the TTL
information reported by DNS. information reported by DNS.
If HTTP clients do not observe this rule, they could be spoofed when If HTTP clients do not observe this rule, they could be spoofed when
a previously-accessed server's IP address changes. As network a previously-accessed server's IP address changes. As network
renumbering is expected to become increasingly common [24], the renumbering is expected to become increasingly common [RFC1900], the
possibility of this form of attack will grow. Observing this possibility of this form of attack will grow. Observing this
requirement thus reduces this potential security vulnerability. requirement thus reduces this potential security vulnerability.
This requirement also improves the load-balancing behavior of clients This requirement also improves the load-balancing behavior of clients
for replicated servers using the same DNS name and reduces the for replicated servers using the same DNS name and reduces the
likelihood of a user's experiencing failure in accessing sites which likelihood of a user's experiencing failure in accessing sites which
use that strategy. use that strategy.
15.4. Location Headers and Spoofing 15.4. Location Headers and Spoofing
If a single server supports multiple organizations that do not trust If a single server supports multiple organizations that do not trust
one another, then it MUST check the values of Location and Content- one another, then it MUST check the values of Location and Content-
Location headers in responses that are generated under control of Location headers in responses that are generated under control of
said organizations to make sure that they do not attempt to said organizations to make sure that they do not attempt to
invalidate resources over which they have no authority. invalidate resources over which they have no authority.
15.5. Content-Disposition Issues 15.5. Content-Disposition Issues
RFC 1806 [35], from which the often implemented Content-Disposition [RFC1806], from which the often implemented Content-Disposition (see
(see Appendix E.1) header in HTTP is derived, has a number of very Appendix E.1) header in HTTP is derived, has a number of very serious
serious security considerations. Content-Disposition is not part of security considerations. Content-Disposition is not part of the HTTP
the HTTP standard, but since it is widely implemented, we are standard, but since it is widely implemented, we are documenting its
documenting its use and risks for implementors. See RFC 2183 [49] use and risks for implementors. See [RFC2183] (which updates RFC
(which updates RFC 1806) for details. 1806) for details.
15.6. Authentication Credentials and Idle Clients 15.6. Authentication Credentials and Idle Clients
Existing HTTP clients and user agents typically retain authentication Existing HTTP clients and user agents typically retain authentication
information indefinitely. HTTP/1.1. does not provide a method for a information indefinitely. HTTP/1.1. does not provide a method for a
server to direct clients to discard these cached credentials. This server to direct clients to discard these cached credentials. This
is a significant defect that requires further extensions to HTTP. is a significant defect that requires further extensions to HTTP.
Circumstances under which credential caching can interfere with the Circumstances under which credential caching can interfere with the
application's security model include but are not limited to: application's security model include but are not limited to:
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15.7.1. Denial of Service Attacks on Proxies 15.7.1. Denial of Service Attacks on Proxies
They exist. They are hard to defend against. Research continues. They exist. They are hard to defend against. Research continues.
Beware. Beware.
16. Acknowledgments 16. Acknowledgments
16.1. (RFC2616) 16.1. (RFC2616)
This specification makes heavy use of the augmented BNF and generic This specification makes heavy use of the augmented BNF and generic
constructs defined by David H. Crocker for RFC 822 [9]. Similarly, constructs defined by David H. Crocker for [RFC822]. Similarly, it
it reuses many of the definitions provided by Nathaniel Borenstein reuses many of the definitions provided by Nathaniel Borenstein and
and Ned Freed for MIME [7]. We hope that their inclusion in this Ned Freed for MIME [RFC2045]. We hope that their inclusion in this
specification will help reduce past confusion over the relationship specification will help reduce past confusion over the relationship
between HTTP and Internet mail message formats. between HTTP and Internet mail message formats.
The HTTP protocol has evolved considerably over the years. It has The HTTP protocol has evolved considerably over the years. It has
benefited from a large and active developer community--the many benefited from a large and active developer community--the many
people who have participated on the www-talk mailing list--and it is people who have participated on the www-talk mailing list--and it is
that community which has been most responsible for the success of that community which has been most responsible for the success of
HTTP and of the World-Wide Web in general. Marc Andreessen, Robert HTTP and of the World-Wide Web in general. Marc Andreessen, Robert
Cailliau, Daniel W. Connolly, Bob Denny, John Franks, Jean-Francois Cailliau, Daniel W. Connolly, Bob Denny, John Franks, Jean-Francois
Groff, Phillip M. Hallam-Baker, Hakon W. Lie, Ari Luotonen, Rob Groff, Phillip M. Hallam-Baker, Hakon W. Lie, Ari Luotonen, Rob
skipping to change at page 170, line 7 skipping to change at page 168, line 7
Much of the content and presentation of the caching design is due to Much of the content and presentation of the caching design is due to
suggestions and comments from individuals including: Shel Kaphan, suggestions and comments from individuals including: Shel Kaphan,
Paul Leach, Koen Holtman, David Morris, and Larry Masinter. Paul Leach, Koen Holtman, David Morris, and Larry Masinter.
Most of the specification of ranges is based on work originally done Most of the specification of ranges is based on work originally done
by Ari Luotonen and John Franks, with additional input from Steve by Ari Luotonen and John Franks, with additional input from Steve
Zilles. Zilles.
Thanks to the "cave men" of Palo Alto. You know who you are. Thanks to the "cave men" of Palo Alto. You know who you are.
Jim Gettys (the editor of [50]) wishes particularly to thank Roy Jim Gettys (the editor of [RFC2616]) wishes particularly to thank Roy
Fielding, the editor of [33], along with John Klensin, Jeff Mogul, Fielding, the editor of [RFC2068], along with John Klensin, Jeff
Paul Leach, Dave Kristol, Koen Holtman, John Franks, Josh Cohen, Alex Mogul, Paul Leach, Dave Kristol, Koen Holtman, John Franks, Josh
Hopmann, Scott Lawrence, and Larry Masinter for their help. And Cohen, Alex Hopmann, Scott Lawrence, and Larry Masinter for their
thanks go particularly to Jeff Mogul and Scott Lawrence for help. And thanks go particularly to Jeff Mogul and Scott Lawrence
performing the "MUST/MAY/SHOULD" audit. for performing the "MUST/MAY/SHOULD" audit.
The Apache Group, Anselm Baird-Smith, author of Jigsaw, and Henrik The Apache Group, Anselm Baird-Smith, author of Jigsaw, and Henrik
Frystyk implemented RFC 2068 early, and we wish to thank them for the Frystyk implemented RFC 2068 early, and we wish to thank them for the
discovery of many of the problems that this document attempts to discovery of many of the problems that this document attempts to
rectify. rectify.
16.2. (This Document) 16.2. (This Document)
This document has benefited greatly from the comments of all those This document has benefited greatly from the comments of all those
participating in the HTTP-WG. In particular, we thank Scott Lawrence participating in the HTTP-WG. In particular, we thank Scott Lawrence
for maintaining the RFC2616 Errata list, and Roy Fielding, Bjoern for maintaining the RFC2616 Errata list, and Roy Fielding, Bjoern
Hoehrmann, Larry Masinter, Howard Melman, Jeff Mogul and Alex Hoehrmann, Larry Masinter, Howard Melman, Jeff Mogul and Alex
Rousskov for contributions to it. Rousskov for contributions to it.
17. References 17. References
17.1. References 17.1. References
[1] Alvestrand, H., "Tags for the Identification of Languages", [ISO-8859]
RFC 1766, March 1995. International Organization for Standardization,
"Information technology - 8-bit single byte coded graphic
[2] Anklesaria, F., McCahill, M., Lindner, P., Johnson, D., Torrey, - character sets", 1987-1990.
D., and B. Alberti, "The Internet Gopher Protocol (a
distributed document search and retrieval protocol)", RFC 1436,
March 1993.
[3] Berners-Lee, T., "Universal Resource Identifiers in WWW: A Part 1: Latin alphabet No. 1, ISO-8859-1:1987. Part 2:
Unifying Syntax for the Expression of Names and Addresses of Latin alphabet No. 2, ISO-8859-2, 1987. Part 3: Latin
Objects on the Network as used in the World-Wide Web", alphabet No. 3, ISO-8859-3, 1988. Part 4: Latin alphabet
RFC 1630, June 1994. No. 4, ISO-8859-4, 1988. Part 5: Latin/Cyrillic alphabet,
ISO-8859-5, 1988. Part 6: Latin/Arabic alphabet, ISO-
8859-6, 1987. Part 7: Latin/Greek alphabet, ISO-8859-7,
1987. Part 8: Latin/Hebrew alphabet, ISO-8859-8, 1988.
Part 9: Latin alphabet No. 5, ISO-8859-9, 1990.
[4] Berners-Lee, T., Masinter, L., and M. McCahill, "Uniform [Luo1998] Luotonen, A., "Tunneling TCP based protocols through Web
Resource Locators (URL)", RFC 1738, December 1994. proxy servers", Work in Progress.
[5] Berners-Lee, T. and D. Connolly, "Hypertext Markup Language - [Nie1997] Nielsen, H., Gettys, J., Prud'hommeaux, E., Lie, H., and
2.0", RFC 1866, November 1995. C. Lilley, "Network Performance Effects of HTTP/1.1, CSS1,
and PNG", Proceedings of ACM SIGCOMM '97, Cannes France ,
Sep 1997.
[6] Berners-Lee, T., Fielding, R., and H. Nielsen, "Hypertext [Pad1995] Padmanabhan, V. and J. Mogul, "Improving HTTP Latency",
Transfer Protocol -- HTTP/1.0", RFC 1945, May 1996. Computer Networks and ISDN Systems v. 28, pp. 25-35,
Dec 1995.
[7] Freed, N. and N. Borenstein, "Multipurpose Internet Mail Slightly revised version of paper in Proc. 2nd
Extensions (MIME) Part One: Format of Internet Message Bodies", International WWW Conference '94: Mosaic and the Web, Oct.
RFC 2045, November 1996. 1994, which is available at <http://www.ncsa.uiuc.edu/SDG/
IT94/Proceedings/DDay/mogul/HTTPLatency.html>.
[8] Braden, R., "Requirements for Internet Hosts - Application and [RFC1036] Horton, M. and R. Adams, "Standard for interchange of
Support", STD 3, RFC 1123, October 1989. USENET messages", RFC 1036, December 1987.
[9] Crocker, D., "Standard for the format of ARPA Internet text [RFC1123] Braden, R., "Requirements for Internet Hosts - Application
messages", STD 11, RFC 822, August 1982. and Support", STD 3, RFC 1123, October 1989.
[10] Davis, F., Kahle, B., Morris, H., Salem, J., Shen, T., Wang, [RFC1305] Mills, D., "Network Time Protocol (Version 3)
R., Sui, J., and M. Grinbaum, "WAIS Interface Protocol Specification, Implementation", RFC 1305, March 1992.
Prototype Functional Specification (v1.5)", Thinking Machines
Corporation , April 1990.
[11] Fielding, R., "Relative Uniform Resource Locators", RFC 1808, [RFC1436] Anklesaria, F., McCahill, M., Lindner, P., Johnson, D.,
June 1995. Torrey, D., and B. Alberti, "The Internet Gopher Protocol
(a distributed document search and retrieval protocol)",
RFC 1436, March 1993.
[12] Horton, M. and R. Adams, "Standard for interchange of USENET [RFC1590] Postel, J., "Media Type Registration Procedure", RFC 1590,
messages", RFC 1036, December 1987. March 1994.
[13] Kantor, B. and P. Lapsley, "Network News Transfer Protocol", [RFC1630] Berners-Lee, T., "Universal Resource Identifiers in WWW: A
RFC 977, February 1986. Unifying Syntax for the Expression of Names and Addresses
of Objects on the Network as used in the World-Wide Web",
RFC 1630, June 1994.
[14] Moore, K., "MIME (Multipurpose Internet Mail Extensions) Part [RFC1700] Reynolds, J. and J. Postel, "Assigned Numbers", STD 2,
Three: Message Header Extensions for Non-ASCII Text", RFC 2047, RFC 1700, October 1994.
November 1996.
[15] Masinter, L. and E. Nebel, "Form-based File Upload in HTML", [RFC1737] Masinter, L. and K. Sollins, "Functional Requirements for
RFC 1867, November 1995. Uniform Resource Names", RFC 1737, December 1994.
[16] Postel, J., "Simple Mail Transfer Protocol", STD 10, RFC 821, [RFC1738] Berners-Lee, T., Masinter, L., and M. McCahill, "Uniform
August 1982. Resource Locators (URL)", RFC 1738, December 1994.
[17] Postel, J., "Media Type Registration Procedure", RFC 1590, [RFC1766] Alvestrand, H., "Tags for the Identification of
March 1994. Languages", RFC 1766, March 1995.
[18] Postel, J. and J. Reynolds, "File Transfer Protocol", STD 9, [RFC1806] Troost, R. and S. Dorner, "Communicating Presentation
RFC 959, October 1985. Information in Internet Messages: The Content-Disposition
Header", RFC 1806, June 1995.
[19] Reynolds, J. and J. Postel, "Assigned Numbers", STD 2, [RFC1808] Fielding, R., "Relative Uniform Resource Locators",
RFC 1700, October 1994. RFC 1808, June 1995.
[20] Masinter, L. and K. Sollins, "Functional Requirements for [RFC1864] Myers, J. and M. Rose, "The Content-MD5 Header Field",
Uniform Resource Names", RFC 1737, December 1994. RFC 1864, October 1995.
[21] American National Standards Institute, "Coded Character Set -- [RFC1866] Berners-Lee, T. and D. Connolly, "Hypertext Markup
7-bit American Standard Code for Information Interchange", Language - 2.0", RFC 1866, November 1995.
ANSI X3.4, 1986.
[22] International Organization for Standardization, "Information [RFC1867] Masinter, L. and E. Nebel, "Form-based File Upload in
technology - 8-bit single byte coded graphic - character sets", HTML", RFC 1867, November 1995.
1987-1990.
Part 1: Latin alphabet No. 1, ISO-8859-1:1987. Part 2: Latin [RFC1900] Carpenter, B. and Y. Rekhter, "Renumbering Needs Work",
alphabet No. 2, ISO-8859-2, 1987. Part 3: Latin alphabet No. RFC 1900, February 1996.
3, ISO-8859-3, 1988. Part 4: Latin alphabet No. 4, ISO-8859-4,
1988. Part 5: Latin/Cyrillic alphabet, ISO-8859-5, 1988. Part
6: Latin/Arabic alphabet, ISO-8859-6, 1987. Part 7: Latin/
Greek alphabet, ISO-8859-7, 1987. Part 8: Latin/Hebrew
alphabet, ISO-8859-8, 1988. Part 9: Latin alphabet No. 5, ISO-
8859-9, 1990.
[23] Myers, J. and M. Rose, "The Content-MD5 Header Field", [RFC1945] Berners-Lee, T., Fielding, R., and H. Nielsen, "Hypertext
RFC 1864, October 1995. Transfer Protocol -- HTTP/1.0", RFC 1945, May 1996.
[24] Carpenter, B. and Y. Rekhter, "Renumbering Needs Work", [RFC1950] Deutsch, L. and J-L. Gailly, "ZLIB Compressed Data Format
RFC 1900, February 1996. Specification version 3.3", RFC 1950, May 1996.
[25] Deutsch, P., Gailly, J-L., Adler, M., Deutsch, L., and G. [RFC1951] Deutsch, P., "DEFLATE Compressed Data Format Specification
version 1.3", RFC 1951, May 1996.
Randers-Pehrson, "GZIP file format specification version 4.3", [RFC1952] Deutsch, P., Gailly, J-L., Adler, M., Deutsch, L., and G.
RFC 1952, May 1996. Randers-Pehrson, "GZIP file format specification version
4.3", RFC 1952, May 1996.
[26] Padmanabhan, V. and J. Mogul, "Improving HTTP Latency", [RFC2026] Bradner, S., "The Internet Standards Process -- Revision
Computer Networks and ISDN Systems v. 28, pp. 25-35, Dec 1995. 3", BCP 9, RFC 2026, October 1996.
Slightly revised version of paper in Proc. 2nd International [RFC2045] Freed, N. and N. Borenstein, "Multipurpose Internet Mail
WWW Conference '94: Mosaic and the Web, Oct. 1994, which is Extensions (MIME) Part One: Format of Internet Message
available at <http://www.ncsa.uiuc.edu/SDG/IT94/Proceedings/ Bodies", RFC 2045, November 1996.
DDay/mogul/HTTPLatency.html>.
[27] Touch, J., Heidemann, J., and K. Obraczka, "Analysis of HTTP [RFC2046] Freed, N. and N. Borenstein, "Multipurpose Internet Mail
Performance", ISI Research Report ISI/RR-98-463 (original Extensions (MIME) Part Two: Media Types", RFC 2046,
report dated Aug.1996), Aug 1998, November 1996.
<http://www.isi.edu/touch/pubs/http-perf96/>.
[28] Mills, D., "Network Time Protocol (Version 3) Specification, [RFC2047] Moore, K., "MIME (Multipurpose Internet Mail Extensions)
Implementation", RFC 1305, March 1992. Part Three: Message Header Extensions for Non-ASCII Text",
RFC 2047, November 1996.
[29] Deutsch, P., "DEFLATE Compressed Data Format Specification [RFC2049] Freed, N. and N. Borenstein, "Multipurpose Internet Mail
version 1.3", RFC 1951, May 1996. Extensions (MIME) Part Five: Conformance Criteria and
Examples", RFC 2049, November 1996.
[30] Spero, S., "Analysis of HTTP Performance Problems", [RFC2068] Fielding, R., Gettys, J., Mogul, J., Nielsen, H., and T.
<http://sunsite.unc.edu/mdma-release/http-prob.html>. Berners-Lee, "Hypertext Transfer Protocol -- HTTP/1.1",
RFC 2068, January 1997.
[31] Deutsch, L. and J-L. Gailly, "ZLIB Compressed Data Format [RFC2069] Franks, J., Hallam-Baker, P., Hostetler, J., Leach, P.,
Specification version 3.3", RFC 1950, May 1996. Luotonen, A., Sink, E., and L. Stewart, "An Extension to
HTTP : Digest Access Authentication", RFC 2069,
January 1997.
[32] Franks, J., Hallam-Baker, P., Hostetler, J., Leach, P., [RFC2076] Palme, J., "Common Internet Message Headers", RFC 2076,
Luotonen, A., Sink, E., and L. Stewart, "An Extension to HTTP : February 1997.
Digest Access Authentication", RFC 2069, January 1997.
[33] Fielding, R., Gettys, J., Mogul, J., Nielsen, H., and T. [RFC2110] Palme, J. and A. Hopmann, "MIME E-mail Encapsulation of
Berners-Lee, "Hypertext Transfer Protocol -- HTTP/1.1", Aggregate Documents, such as HTML (MHTML)", RFC 2110,
RFC 2068, January 1997. March 1997.
[34] Bradner, S., "Key words for use in RFCs to Indicate Requirement [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[35] Troost, R. and S. Dorner, "Communicating Presentation [RFC2145] Mogul, J., Fielding, R., Gettys, J., and H. Nielsen, "Use
Information in Internet Messages: The Content-Disposition and Interpretation of HTTP Version Numbers", RFC 2145,
Header", RFC 1806, June 1995. May 1997.
[36] Mogul, J., Fielding, R., Gettys, J., and H. Nielsen, "Use and [RFC2183] Troost, R., Dorner, S., and K. Moore, "Communicating
Interpretation of HTTP Version Numbers", RFC 2145, May 1997. Presentation Information in Internet Messages: The
Content-Disposition Header Field", RFC 2183, August 1997.
[37] Palme, J., "Common Internet Message Headers", RFC 2076, [RFC2277] Alvestrand, H., "IETF Policy on Character Sets and
February 1997. Languages", BCP 18, RFC 2277, January 1998.
[38] Yergeau, F., "UTF-8, a transformation format of ISO 10646", [RFC2279] Yergeau, F., "UTF-8, a transformation format of ISO
RFC 2279, January 1998. 10646", RFC 2279, January 1998.
[39] Nielsen, H., Gettys, J., Prud'hommeaux, E., Lie, H., and C. [RFC2324] Masinter, L., "Hyper Text Coffee Pot Control Protocol
Lilley, "Network Performance Effects of HTTP/1.1, CSS1, and (HTCPCP/1.0)", RFC 2324, April 1998.
PNG", Proceedings of ACM SIGCOMM '97, Cannes France , Sep 1997.
[40] Freed, N. and N. Borenstein, "Multipurpose Internet Mail [RFC2396] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Extensions (MIME) Part Two: Media Types", RFC 2046, Resource Identifiers (URI): Generic Syntax", RFC 2396,
November 1996. August 1998.
[41] Alvestrand, H., "IETF Policy on Character Sets and Languages", [RFC2617] Franks, J., Hallam-Baker, P., Hostetler, J., Lawrence, S.,
BCP 18, RFC 2277, January 1998. Leach, P., Luotonen, A., and L. Stewart, "HTTP
Authentication: Basic and Digest Access Authentication",
RFC 2617, June 1999.
[42] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform [RFC821] Postel, J., "Simple Mail Transfer Protocol", STD 10,
Resource Identifiers (URI): Generic Syntax", RFC 2396, RFC 821, August 1982.
August 1998.
[43] Franks, J., Hallam-Baker, P., Hostetler, J., Lawrence, S., [RFC822] Crocker, D., "Standard for the format of ARPA Internet
Leach, P., Luotonen, A., and L. Stewart, "HTTP Authentication: text messages", STD 11, RFC 822, August 1982.
Basic and Digest Access Authentication", RFC 2617, June 1999.
[44] Luotonen, A., "Tunneling TCP based protocols through Web proxy [RFC959] Postel, J. and J. Reynolds, "File Transfer Protocol",
servers", Work in Progress. STD 9, RFC 959, October 1985.
[45] Palme, J. and A. Hopmann, "MIME E-mail Encapsulation of [RFC977] Kantor, B. and P. Lapsley, "Network News Transfer
Aggregate Documents, such as HTML (MHTML)", RFC 2110, Protocol", RFC 977, February 1986.
March 1997.
[46] Bradner, S., "The Internet Standards Process -- Revision 3", [Spero] Spero, S., "Analysis of HTTP Performance Problems",
BCP 9, RFC 2026, October 1996. <http://sunsite.unc.edu/mdma-release/http-prob.html>.
[47] Masinter, L., "Hyper Text Coffee Pot Control Protocol [Tou1998] Touch, J., Heidemann, J., and K. Obraczka, "Analysis of
(HTCPCP/1.0)", RFC 2324, April 1998. HTTP Performance", ISI Research Report ISI/RR-98-463
(original report dated Aug.1996), Aug 1998,
<http://www.isi.edu/touch/pubs/http-perf96/>.
[48] Freed, N. and N. Borenstein, "Multipurpose Internet Mail [USASCII] American National Standards Institute, "Coded Character
Extensions (MIME) Part Five: Conformance Criteria and Set -- 7-bit American Standard Code for Information
Examples", RFC 2049, November 1996. Interchange", ANSI X3.4, 1986.
[49] Troost, R., Dorner, S., and K. Moore, "Communicating [WAIS] Davis, F., Kahle, B., Morris, H., Salem, J., Shen, T.,
Presentation Information in Internet Messages: The Content- Wang, R., Sui, J., and M. Grinbaum, "WAIS Interface
Disposition Header Field", RFC 2183, August 1997. Protocol Prototype Functional Specification (v1.5)",
Thinking Machines Corporation , April 1990.
17.2. Informative References 17.2. Informative References
[50] Fielding, R., Gettys, J., Mogul, J., Frystyk, H., Masinter, L., [RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
Leach, P., and T. Berners-Lee, "Hypertext Transfer Protocol -- Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext
HTTP/1.1", RFC 2616, June 1999. Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.
URIs URIs
[51] <mailto:ietf-http-wg@w3.org> [1] <mailto:ietf-http-wg@w3.org>
[52] <mailto:ietf-http-wg-request@w3.org?subject=subscribe> [2] <mailto:ietf-http-wg-request@w3.org?subject=subscribe>
Appendix A. Internet Media Type message/http and application/http Appendix A. Internet Media Type message/http and application/http
In addition to defining the HTTP/1.1 protocol, this document serves In addition to defining the HTTP/1.1 protocol, this document serves
as the specification for the Internet media type "message/http" and as the specification for the Internet media type "message/http" and
"application/http". The message/http type can be used to enclose a "application/http". The message/http type can be used to enclose a
single HTTP request or response message, provided that it obeys the single HTTP request or response message, provided that it obeys the
MIME restrictions for all "message" types regarding line length and MIME restrictions for all "message" types regarding line length and
encodings. The application/http type can be used to enclose a encodings. The application/http type can be used to enclose a
pipeline of one or more HTTP request or response messages (not pipeline of one or more HTTP request or response messages (not
intermixed). The following is to be registered with IANA [17]. intermixed). The following is to be registered with IANA [RFC1590].
Media Type name: message Media Type name: message
Media subtype name: http Media subtype name: http
Required parameters: none Required parameters: none
Optional parameters: version, msgtype Optional parameters: version, msgtype
version: The HTTP-Version number of the enclosed message (e.g., version: The HTTP-Version number of the enclosed message (e.g.,
skipping to change at page 179, line 8 skipping to change at page 178, line 8
Content-range: bytes 7000-7999/8000 Content-range: bytes 7000-7999/8000
...the second range ...the second range
--THIS_STRING_SEPARATES-- --THIS_STRING_SEPARATES--
Notes: Notes:
1. Additional CRLFs may precede the first boundary string in the 1. Additional CRLFs may precede the first boundary string in the
entity. entity.
2. Although RFC 2046 [40] permits the boundary string to be quoted, 2. Although [RFC2046] permits the boundary string to be quoted, some
some existing implementations handle a quoted boundary string existing implementations handle a quoted boundary string
incorrectly. incorrectly.
3. A number of browsers and servers were coded to an early draft of 3. A number of browsers and servers were coded to an early draft of
the byteranges specification to use a media type of multipart/ the byteranges specification to use a media type of multipart/
x-byteranges, which is almost, but not quite compatible with the x-byteranges, which is almost, but not quite compatible with the
version documented in HTTP/1.1. version documented in HTTP/1.1.
Appendix C. Tolerant Applications Appendix C. Tolerant Applications
Although this document specifies the requirements for the generation Although this document specifies the requirements for the generation
skipping to change at page 180, line 25 skipping to change at page 179, line 25
accept any amount of SP or HT characters between fields, even though accept any amount of SP or HT characters between fields, even though
only a single SP is required. only a single SP is required.
The line terminator for message-header fields is the sequence CRLF. The line terminator for message-header fields is the sequence CRLF.
However, we recommend that applications, when parsing such headers, However, we recommend that applications, when parsing such headers,
recognize a single LF as a line terminator and ignore the leading CR. recognize a single LF as a line terminator and ignore the leading CR.
The character set of an entity-body SHOULD be labeled as the lowest The character set of an entity-body SHOULD be labeled as the lowest
common denominator of the character codes used within that body, with common denominator of the character codes used within that body, with
the exception that not labeling the entity is preferred over labeling the exception that not labeling the entity is preferred over labeling
the entity with the labels US-ASCII or ISO-8859-1. See section 3.7.1 the entity with the labels US-ASCII or ISO-8859-1. See Section 3.7.1
and 3.4.1. and 3.4.1.
Additional rules for requirements on parsing and encoding of dates Additional rules for requirements on parsing and encoding of dates
and other potential problems with date encodings include: and other potential problems with date encodings include:
o HTTP/1.1 clients and caches SHOULD assume that an RFC-850 date o HTTP/1.1 clients and caches SHOULD assume that an RFC-850 date
which appears to be more than 50 years in the future is in fact in which appears to be more than 50 years in the future is in fact in
the past (this helps solve the "year 2000" problem). the past (this helps solve the "year 2000" problem).
o An HTTP/1.1 implementation MAY internally represent a parsed o An HTTP/1.1 implementation MAY internally represent a parsed
skipping to change at page 181, line 7 skipping to change at page 180, line 7
o All expiration-related calculations MUST be done in GMT. The o All expiration-related calculations MUST be done in GMT. The
local time zone MUST NOT influence the calculation or comparison local time zone MUST NOT influence the calculation or comparison
of an age or expiration time. of an age or expiration time.
o If an HTTP header incorrectly carries a date value with a time o If an HTTP header incorrectly carries a date value with a time
zone other than GMT, it MUST be converted into GMT using the most zone other than GMT, it MUST be converted into GMT using the most
conservative possible conversion. conservative possible conversion.
Appendix D. Differences Between HTTP Entities and RFC 2045 Entities Appendix D. Differences Between HTTP Entities and RFC 2045 Entities
HTTP/1.1 uses many of the constructs defined for Internet Mail (RFC HTTP/1.1 uses many of the constructs defined for Internet Mail
822 [9]) and the Multipurpose Internet Mail Extensions (MIME [7]) to ([RFC822]) and the Multipurpose Internet Mail Extensions (MIME
allow entities to be transmitted in an open variety of [RFC2045]) to allow entities to be transmitted in an open variety of
representations and with extensible mechanisms. However, RFC 2045 representations and with extensible mechanisms. However, RFC 2045
discusses mail, and HTTP has a few features that are different from discusses mail, and HTTP has a few features that are different from
those described in RFC 2045. These differences were carefully chosen those described in RFC 2045. These differences were carefully chosen
to optimize performance over binary connections, to allow greater to optimize performance over binary connections, to allow greater
freedom in the use of new media types, to make date comparisons freedom in the use of new media types, to make date comparisons
easier, and to acknowledge the practice of some early HTTP servers easier, and to acknowledge the practice of some early HTTP servers
and clients. and clients.
This appendix describes specific areas where HTTP differs from RFC This appendix describes specific areas where HTTP differs from RFC
2045. Proxies and gateways to strict MIME environments SHOULD be 2045. Proxies and gateways to strict MIME environments SHOULD be
skipping to change at page 181, line 31 skipping to change at page 180, line 31
where necessary. Proxies and gateways from MIME environments to HTTP where necessary. Proxies and gateways from MIME environments to HTTP
also need to be aware of the differences because some conversions also need to be aware of the differences because some conversions
might be required. might be required.
D.1. MIME-Version D.1. MIME-Version
HTTP is not a MIME-compliant protocol. However, HTTP/1.1 messages HTTP is not a MIME-compliant protocol. However, HTTP/1.1 messages
MAY include a single MIME-Version general-header field to indicate MAY include a single MIME-Version general-header field to indicate
what version of the MIME protocol was used to construct the message. what version of the MIME protocol was used to construct the message.
Use of the MIME-Version header field indicates that the message is in Use of the MIME-Version header field indicates that the message is in
full compliance with the MIME protocol (as defined in RFC 2045[7]). full compliance with the MIME protocol (as defined in [RFC2045]).
Proxies/gateways are responsible for ensuring full compliance (where Proxies/gateways are responsible for ensuring full compliance (where
possible) when exporting HTTP messages to strict MIME environments. possible) when exporting HTTP messages to strict MIME environments.
MIME-Version = "MIME-Version" ":" 1*DIGIT "." 1*DIGIT MIME-Version = "MIME-Version" ":" 1*DIGIT "." 1*DIGIT
MIME version "1.0" is the default for use in HTTP/1.1. However, MIME version "1.0" is the default for use in HTTP/1.1. However,
HTTP/1.1 message parsing and semantics are defined by this document HTTP/1.1 message parsing and semantics are defined by this document
and not the MIME specification. and not the MIME specification.
D.2. Conversion to Canonical Form D.2. Conversion to Canonical Form
RFC 2045 [7] requires that an Internet mail entity be converted to [RFC2045] requires that an Internet mail entity be converted to
canonical form prior to being transferred, as described in section 4 canonical form prior to being transferred, as described in Section 4
of RFC 2049 [48]. Section 3.7.1 of this document describes the forms of [RFC2049]. Section 3.7.1 of this document describes the forms
allowed for subtypes of the "text" media type when transmitted over allowed for subtypes of the "text" media type when transmitted over
HTTP. RFC 2046 requires that content with a type of "text" represent HTTP. RFC 2046 requires that content with a type of "text" represent
line breaks as CRLF and forbids the use of CR or LF outside of line line breaks as CRLF and forbids the use of CR or LF outside of line
break sequences. HTTP allows CRLF, bare CR, and bare LF to indicate break sequences. HTTP allows CRLF, bare CR, and bare LF to indicate
a line break within text content when a message is transmitted over a line break within text content when a message is transmitted over
HTTP. HTTP.
Where it is possible, a proxy or gateway from HTTP to a strict MIME Where it is possible, a proxy or gateway from HTTP to a strict MIME
environment SHOULD translate all line breaks within the text media environment SHOULD translate all line breaks within the text media
types described in Section 3.7.1 of this document to the RFC 2049 types described in Section 3.7.1 of this document to the RFC 2049
skipping to change at page 183, line 32 skipping to change at page 182, line 32
read entity-header read entity-header
while (entity-header not empty) { while (entity-header not empty) {
append entity-header to existing header fields append entity-header to existing header fields
read entity-header read entity-header
} }
Content-Length := length Content-Length := length
Remove "chunked" from Transfer-Encoding Remove "chunked" from Transfer-Encoding
D.7. MHTML and Line Length Limitations D.7. MHTML and Line Length Limitations
HTTP implementations which share code with MHTML [45] implementations HTTP implementations which share code with MHTML [RFC2110]
need to be aware of MIME line length limitations. Since HTTP does implementations need to be aware of MIME line length limitations.
not have this limitation, HTTP does not fold long lines. MHTML Since HTTP does not have this limitation, HTTP does not fold long
messages being transported by HTTP follow all conventions of MHTML, lines. MHTML messages being transported by HTTP follow all
including line length limitations and folding, canonicalization, conventions of MHTML, including line length limitations and folding,
etc., since HTTP transports all message-bodies as payload (see canonicalization, etc., since HTTP transports all message-bodies as
Section 3.7.2) and does not interpret the content or any MIME header payload (see Section 3.7.2) and does not interpret the content or any
lines that might be contained therein. MIME header lines that might be contained therein.
Appendix E. Additional Features Appendix E. Additional Features
RFC 1945 and RFC 2068 document protocol elements used by some RFC 1945 and RFC 2068 document protocol elements used by some
existing HTTP implementations, but not consistently and correctly existing HTTP implementations, but not consistently and correctly
across most HTTP/1.1 applications. Implementors are advised to be across most HTTP/1.1 applications. Implementors are advised to be
aware of these features, but cannot rely upon their presence in, or aware of these features, but cannot rely upon their presence in, or
interoperability with, other HTTP/1.1 applications. Some of these interoperability with, other HTTP/1.1 applications. Some of these
describe proposed experimental features, and some describe features describe proposed experimental features, and some describe features
that experimental deployment found lacking that are now addressed in that experimental deployment found lacking that are now addressed in
the base HTTP/1.1 specification. the base HTTP/1.1 specification.
A number of other headers, such as Content-Disposition and Title, A number of other headers, such as Content-Disposition and Title,
from SMTP and MIME are also often implemented (see RFC 2076 [37]). from SMTP and MIME are also often implemented (see [RFC2076]).
E.1. Content-Disposition E.1. Content-Disposition
The Content-Disposition response-header field has been proposed as a The Content-Disposition response-header field has been proposed as a
means for the origin server to suggest a default filename if the user means for the origin server to suggest a default filename if the user
requests that the content is saved to a file. This usage is derived requests that the content is saved to a file. This usage is derived
from the definition of Content-Disposition in RFC 1806 [35]. from the definition of Content-Disposition in [RFC1806].
content-disposition = "Content-Disposition" ":" content-disposition = "Content-Disposition" ":"
disposition-type *( ";" disposition-parm ) disposition-type *( ";" disposition-parm )
disposition-type = "attachment" | disp-extension-token disposition-type = "attachment" | disp-extension-token
disposition-parm = filename-parm | disp-extension-parm disposition-parm = filename-parm | disp-extension-parm
filename-parm = "filename" "=" quoted-string filename-parm = "filename" "=" quoted-string
disp-extension-token = token disp-extension-token = token
disp-extension-parm = token "=" ( token | quoted-string ) disp-extension-parm = token "=" ( token | quoted-string )
An example is An example is
skipping to change at page 185, line 33 skipping to change at page 184, line 33
o recognize the format of the Status-Line for HTTP/1.0 and 1.1 o recognize the format of the Status-Line for HTTP/1.0 and 1.1
responses; responses;
o understand any valid response in the format of HTTP/0.9, 1.0, or o understand any valid response in the format of HTTP/0.9, 1.0, or
1.1. 1.1.
For most implementations of HTTP/1.0, each connection is established For most implementations of HTTP/1.0, each connection is established
by the client prior to the request and closed by the server after by the client prior to the request and closed by the server after
sending the response. Some implementations implement the Keep-Alive sending the response. Some implementations implement the Keep-Alive
version of persistent connections described in Section 19.7.1 of RFC version of persistent connections described in Section 19.7.1 of
2068 [33]. [RFC2068].
F.1. Changes from HTTP/1.0 F.1. Changes from HTTP/1.0
This section summarizes major differences between versions HTTP/1.0 This section summarizes major differences between versions HTTP/1.0
and HTTP/1.1. and HTTP/1.1.
F.1.1. Changes to Simplify Multi-homed Web Servers and Conserve IP F.1.1. Changes to Simplify Multi-homed Web Servers and Conserve IP
Addresses Addresses
The requirements that clients and servers support the Host request- The requirements that clients and servers support the Host request-
skipping to change at page 186, line 51 skipping to change at page 185, line 51
However, talking to proxies is the most important use of persistent However, talking to proxies is the most important use of persistent
connections, so that prohibition is clearly unacceptable. Therefore, connections, so that prohibition is clearly unacceptable. Therefore,
we need some other mechanism for indicating a persistent connection we need some other mechanism for indicating a persistent connection
is desired, which is safe to use even when talking to an old proxy is desired, which is safe to use even when talking to an old proxy
that ignores Connection. Persistent connections are the default for that ignores Connection. Persistent connections are the default for
HTTP/1.1 messages; we introduce a new keyword (Connection: close) for HTTP/1.1 messages; we introduce a new keyword (Connection: close) for
declaring non-persistence. See Section 14.10. declaring non-persistence. See Section 14.10.
The original HTTP/1.0 form of persistent connections (the Connection: The original HTTP/1.0 form of persistent connections (the Connection:
Keep-Alive and Keep-Alive header) is documented in RFC 2068. [33] Keep-Alive and Keep-Alive header) is documented in [RFC2068].
F.3. Changes from RFC 2068 F.3. Changes from RFC 2068
This specification has been carefully audited to correct and This specification has been carefully audited to correct and
disambiguate key word usage; RFC 2068 had many problems in respect to disambiguate key word usage; RFC 2068 had many problems in respect to
the conventions laid out in RFC 2119 [34]. the conventions laid out in [RFC2119].
Clarified which error code should be used for inbound server failures Clarified which error code should be used for inbound server failures
(e.g. DNS failures). (Section 10.5.5). (e.g. DNS failures). (Section 10.5.5).
CREATE had a race that required an Etag be sent when a resource is CREATE had a race that required an Etag be sent when a resource is
first created. (Section 10.2.2). first created. (Section 10.2.2).
Content-Base was deleted from the specification: it was not Content-Base was deleted from the specification: it was not
implemented widely, and there is no simple, safe way to introduce it implemented widely, and there is no simple, safe way to introduce it
without a robust extension mechanism. In addition, it is used in a without a robust extension mechanism. In addition, it is used in a
similar, but not identical fashion in MHTML [45]. similar, but not identical fashion in MHTML [RFC2110].
Transfer-coding and message lengths all interact in ways that Transfer-coding and message lengths all interact in ways that
required fixing exactly when chunked encoding is used (to allow for required fixing exactly when chunked encoding is used (to allow for
transfer encoding that may not be self delimiting); it was important transfer encoding that may not be self delimiting); it was important
to straighten out exactly how message lengths are computed. to straighten out exactly how message lengths are computed.
(Sections 3.6, 4.4, 7.2.2, 13.5.2, 14.13, 14.16) (Sections 3.6, 4.4, 7.2.2, 13.5.2, 14.13, 14.16)
A content-coding of "identity" was introduced, to solve problems A content-coding of "identity" was introduced, to solve problems
discovered in caching. (Section 3.5) discovered in caching. (Section 3.5)
skipping to change at page 188, line 47 skipping to change at page 187, line 47
5. Require that the origin server MUST NOT wait for the request body 5. Require that the origin server MUST NOT wait for the request body
before it sends a required 100 (Continue) response. before it sends a required 100 (Continue) response.
6. Allow, rather than require, a server to omit 100 (Continue) if it 6. Allow, rather than require, a server to omit 100 (Continue) if it
has already seen some of the request body. has already seen some of the request body.
7. Allow servers to defend against denial-of-service attacks and 7. Allow servers to defend against denial-of-service attacks and
broken clients. broken clients.
This change adds the Expect header and 417 status code. The message This change adds the Expect header and 417 status code. The message
transmission requirements fixes are in sections 8.2, 10.4.18, transmission requirements fixes are in Sections 8.2, 10.4.18,
8.1.2.2, 13.11, and 14.20. 8.1.2.2, 13.11, and 14.20.
Proxies should be able to add Content-Length when appropriate. Proxies should be able to add Content-Length when appropriate.
(Section 13.5.2) (Section 13.5.2)
Clean up confusion between 403 and 404 responses. (Section 10.4.4, Clean up confusion between 403 and 404 responses. (Section 10.4.4,
10.4.5, and 10.4.11) 10.4.5, and 10.4.11)
Warnings could be cached incorrectly, or not updated appropriately. Warnings could be cached incorrectly, or not updated appropriately.
(Section 13.1.2, 13.2.4, 13.5.2, 13.5.3, 14.9.3, and 14.46) Warning (Section 13.1.2, 13.2.4, 13.5.2, 13.5.3, 14.9.3, and 14.46) Warning
also needed to be a general header, as PUT or other methods may have also needed to be a general header, as PUT or other methods may have
skipping to change at page 189, line 24 skipping to change at page 188, line 24
codings become as full fledged as content-codings. This involves codings become as full fledged as content-codings. This involves
adding an IANA registry for transfer-codings (separate from content adding an IANA registry for transfer-codings (separate from content
codings), a new header field (TE) and enabling trailer headers in the codings), a new header field (TE) and enabling trailer headers in the
future. Transfer encoding is a major performance benefit, so it was future. Transfer encoding is a major performance benefit, so it was
worth fixing [39]. TE also solves another, obscure, downward worth fixing [39]. TE also solves another, obscure, downward
interoperability problem that could have occurred due to interactions interoperability problem that could have occurred due to interactions
between authentication trailers, chunked encoding and HTTP/1.0 between authentication trailers, chunked encoding and HTTP/1.0
clients.(Section 3.6, 3.6.1, and 14.39) clients.(Section 3.6, 3.6.1, and 14.39)
The PATCH, LINK, UNLINK methods were defined but not commonly The PATCH, LINK, UNLINK methods were defined but not commonly
implemented in previous versions of this specification. See RFC 2068 implemented in previous versions of this specification. See
[33]. [RFC2068].
The Alternates, Content-Version, Derived-From, Link, URI, Public and The Alternates, Content-Version, Derived-From, Link, URI, Public and
Content-Base header fields were defined in previous versions of this Content-Base header fields were defined in previous versions of this
specification, but not commonly implemented. See RFC 2068 [33]. specification, but not commonly implemented. See [RFC2068].
F.4. Changes from RFC 2616 F.4. Changes from RFC 2616
Clarify that HTTP-Version is case sensitive. (Section 3.1) Clarify that HTTP-Version is case sensitive. (Section 3.1)
Eliminate overlooked reference to "unsafe" characters. Eliminate overlooked reference to "unsafe" characters.
(Section 3.2.3) (Section 3.2.3)
Clarify contexts that charset is used in. (Section 3.4) Clarify contexts that charset is used in. (Section 3.4)
Remove reference to non-existant identity transfer-coding value Remove reference to non-existant identity transfer-coding value
tokens. (Sections 3.6, 4.4 and D.5) tokens. (Sections 3.6, 4.4 and D.5)
Clarification that the chunk length does not include the count of the Clarification that the chunk length does not include the count of the
octets in the chunk header and trailer. (Section 3.6.1) octets in the chunk header and trailer. (Section 3.6.1)
Fix BNF to add query, as the abs_path production in Section 3 of [42] Fix BNF to add query, as the abs_path production in Section 3 of
doesn't define it. (Section 5.1.2) [RFC2396] doesn't define it. (Section 5.1.2)
Clarify definition of POST. (Section 9.5) Clarify definition of POST. (Section 9.5)
Clarify that it's not ok to use a weak cache validator in a 206 Clarify that it's not ok to use a weak cache validator in a 206
response. (Section 10.2.7) response. (Section 10.2.7)
Failed to consider that there are many other request methods that are Failed to consider that there are many other request methods that are
safe to automatically redirect, and further that the user agent is safe to automatically redirect, and further that the user agent is
able to make that determination based on the request method able to make that determination based on the request method
semantics. (Sections 10.3.2, 10.3.3 and 10.3.8 ) semantics. (Sections 10.3.2, 10.3.3 and 10.3.8 )
skipping to change at page 192, line 5 skipping to change at page 190, line 35
Reformat HTTP-WG contributors as a plain text paragraph. Reformat HTTP-WG contributors as a plain text paragraph.
Change [RFC2616] to be an informative reference. Fix RFC2026 Change [RFC2616] to be an informative reference. Fix RFC2026
reference (broken in draft 00). Outdent artwork to more closely reference (broken in draft 00). Outdent artwork to more closely
match RFC2616. (No change tracking for these changes). match RFC2616. (No change tracking for these changes).
Mark Yves Lafon and Julian Reschke as "Editor" in the front page and Mark Yves Lafon and Julian Reschke as "Editor" in the front page and
the Authors section. Re-add all of the authors of RFC2616 for now. the Authors section. Re-add all of the authors of RFC2616 for now.
(No change tracking for these changes). (No change tracking for these changes).
G.3. Since draft-lafon-rfc2616bis-01
Add issues "fragment-combination" and
"rfc2048_informative_and_obsolete".
Resolve issues "location-fragments" (by moving the remaining issue
into the new issue "fragment-combination") and "media-reg" (by adding
"rfc2048_informative_and_obsolete" instead).
Reopen and close issue "rfc2606-compliance" again (other instances
where found).
Add and resolve issue "references_style".
Appendix H. Resolved issues (to be removed by RFC Editor before Appendix H. Resolved issues (to be removed by RFC Editor before
publication) publication)
Issues that were either rejected or resolved in this version of this Issues that were either rejected or resolved in this version of this
document. document.
H.1. rfc2606-compliance H.1. rfc2606-compliance
Type: edit Type: edit
<http://www.w3.org/Protocols/HTTP/1.1/rfc2616bis/issues/#i42>
julian.reschke@greenbytes.de (2006-10-19): Make sure that domain julian.reschke@greenbytes.de (2006-10-19): Make sure that domain
names in examples use names reserved for that purpose (see RFC2606). names in examples use names reserved for that purpose (see RFC2606).
Resolution: Done. Resolution (2006-11-02): Done.
H.2. editor-notes
Type: edit
<http://purl.org/NET/http-errata#editor-notes>
fielding@kiwi.ics.uci.edu (1999-08-03): See http://lists.w3.org/
Archives/Public/ietf-http-wg-old/1999MayAug/0102.html.
Resolution (2006-10-14): Not applicable. New References section is
generated by xml2rfc.
H.3. verscase
In Section 3.1:
Type: change
<http://purl.org/NET/http-errata#verscase>
fielding@apache.org (2002-09-16): See http://lists.w3.org/Archives/
Public/ietf-http-wg/2002JulSep/0066.html.
Resolution (2006-10-14): Resolved as per
http://purl.org/NET/http-errata#verscase.
H.4. unsafe-uri
In Section 3.2.3:
Type: change
<http://purl.org/NET/http-errata#unsafe-uri>
fielding@kiwi.ICS.UCI.EDU (1999-09-10): See
http://ftp.ics.uci.edu/pub/ietf/http/hypermail/1999/0273.html.
Resolution (2006-10-14): Resolved as per
http://purl.org/NET/http-errata#unsafe-uri.
H.5. charactersets
In Section 3.4:
Type: change
<http://purl.org/NET/http-errata#charactersets>
Howard@silverstream.com (2001-02-08): See http://lists.w3.org/
Archives/Public/ietf-http-wg-old/2001JanApr/0022.html.
Resolution (2006-10-14): Resolved as per
http://purl.org/NET/http-errata#charactersets.
H.6. identity
In Section 3.6:
Type: change
<http://purl.org/NET/http-errata#identity>
LMM@acm.org (2001-11-05): See http://lists.w3.org/Archives/Public/
ietf-http-wg-old/2001SepDec/0018.html.
Resolution (2006-10-14): Resolved as per
http://purl.org/NET/http-errata#identity.
H.7. chunk-size
In Section 3.6.1:
Type: change
<http://purl.org/NET/http-errata#chunk-size>
wham_bang@yahoo.com (1999-06-02): See http://lists.w3.org/Archives/
Public/ietf-http-wg-old/1999MayAug/0018.html.
Resolution (2006-10-14): Resolved as per
http://purl.org/NET/http-errata#chunk-size.
H.8. msg-len-chars
In Section 4.4:
Type: edit
<http://purl.org/NET/http-errata#msg-len-chars>
fielding@kiwi.ics.uci.edu (1999-08-03): See http://lists.w3.org/
Archives/Public/ietf-http-wg-old/1999MayAug/0102.html.
Resolution (2006-10-13): Resolved as per
http://purl.org/NET/http-errata#msg-len-chars.
H.9. uriquery
In Section 5.1:
Type: change
<http://purl.org/NET/http-errata#uriquery>
LMM@acm.org (2001-07-30): See http://lists.w3.org/Archives/Public/
ietf-http-wg-old/2001MayAug/0034.html.
Resolution (2006-10-14): Resolved as per
http://purl.org/NET/http-errata#uriquery.
H.10. post
In Section 9.5:
Type: change
<http://purl.org/NET/http-errata#post>
mogul@pa.dec.com (2002-04-09): See http://lists.w3.org/Archives/
Public/ietf-http-wg-old/2002JanApr/0024.html.
Resolution (2006-10-16): Resolved as per
http://purl.org/NET/http-errata#post.
H.11. ifrange206
In Section 10.2.7:
Type: change
<http://purl.org/NET/http-errata#identity>
rousskov@measurement-factory.com (2003-04-15): See http://
lists.w3.org/Archives/Public/ietf-http-wg/2003AprJun/0003.html.
Resolution (2006-10-16): Resolved as per
http://purl.org/NET/http-errata#ifrange206.
H.12. saferedirect
In Section 10.3.2:
Type: change
<http://purl.org/NET/http-errata#saferedirect>
fielding@ebuilt.com (2001-03-03): See http://lists.w3.org/Archives/
Public/ietf-http-wg-old/2001JanApr/0031.html.
Resolution (2006-10-14): Resolved as per
http://purl.org/NET/http-errata#saferedirect.
H.13. trailer-hop
In Section 13.5.1: H.2. references_style
Type: edit Type: edit
<http://purl.org/NET/http-errata#trailer-hop> <http://lists.w3.org/Archives/Public/ietf-http-wg/2006OctDec/
0182.html>
mogul@pa.dec.com (2000-12-04): See http://lists.w3.org/Archives/ julian.reschke@greenbytes.de (2006-11-12): Change references style to
Public/ietf-http-wg-old/2000SepDec/0127.html. symbolic ("[RFC2396]") instead of ("[42]").
Resolution (2006-10-14): Resolved as per Resolution (2006-11-19): Done.
http://purl.org/NET/http-errata#trailer-hop.
H.14. invalidupd H.3. media-reg
In Section 13.10: In Section 3.7:
Type: change Type: change
<http://purl.org/NET/http-errata#invalidupd> <http://purl.org/NET/http-errata#media-reg>
Jeff.Mogul@hp.com (2002-06-21): See http://lists.w3.org/Archives/ derhoermi@gmx.net (2000-09-10): See
Public/ietf-http-wg/2002AprJun/0058.html. http://lists.w3.org/Archives/Public/ietf-http-wg-old/2000SepDec/0013.
Resolution (2006-10-14): Resolved as per Resolution (2006-11-14): Done (note that RFC2048 has been obsoleted
http://purl.org/NET/http-errata#invalidupd. now as well; see separate issue rfc2048_informative_and_obsolete).
Note that the prosed resolution in
http://purl.org/NET/http-errata#media-reg contains typos both in the
original text ("4288" rather than "1590") and in the proposed
resolution ("Mulitpurpose").
H.15. noclose1xx H.4. location-fragments
In Section 14.10: In Section 14.30:
Type: change Type: change
<http://purl.org/NET/http-errata#noclose1xx> <http://purl.org/NET/http-errata#location-fragments>
fielding@ebuilt.com (2001-11-08): See http://lists.w3.org/Archives/
Public/ietf-http-wg-old/2001SepDec/0022.html.
Resolution (2006-10-14): Resolved as per
http://purl.org/NET/http-errata#noclose1xx.
H.16. via-must
In Section 14.38:
Type: change
<http://purl.org/NET/http-errata#via-must> fielding@kiwi.ics.uci.edu (1999-08-06): See
http://lists.w3.org/Archives/Public/ietf-http-wg-old/1999MayAug/0103.
julian.reschke@greenbytes.de (2006-10-14): See julian.reschke@greenbytes.de (2006-10-16): Fix BNF and add note about
http://purl.org/NET/http-errata#via-must. when it's appropriate to use fragments as suggested in
http://purl.org/NET/http-errata#location-fragments. This leaves us
with the open issue: _At present, the behavior in the case where
there was a fragment with the original URI, e.g.:
http://host1.example.com/resource1#fragment1 where /resource1
redirects to http://host2.example.com/resource2#fragment2 is
'fragment1' discarded? Do you find fragment2 and then find fragment1
within it? We don't have fragment combination rules._.
Resolution (2006-10-14): Resolved as per Resolution (2006-10-27): Close this issue (with fixes in draft 01),
http://purl.org/NET/http-errata#via-must. and add the new issue fragment-combination to deal with the remaining
issue.
Appendix I. Open issues (to be removed by RFC Editor prior to Appendix I. Open issues (to be removed by RFC Editor prior to
publication) publication)
I.1. rfc2616bis I.1. rfc2616bis
Type: edit Type: edit
julian.reschke@greenbytes.de (2006-10-10): Umbrella issue for changes julian.reschke@greenbytes.de (2006-10-10): Umbrella issue for changes
with respect to the revision process itself. with respect to the revision process itself.
skipping to change at page 197, line 32 skipping to change at page 193, line 32
julian.reschke@greenbytes.de (2006-10-19): The reference entries for julian.reschke@greenbytes.de (2006-10-19): The reference entries for
RFC1866, RFC2069 and RFC2026 are unused. Remove them? RFC1866, RFC2069 and RFC2026 are unused. Remove them?
I.3. edit I.3. edit
Type: edit Type: edit
julian.reschke@greenbytes.de (2006-10-08): Umbrella issue for julian.reschke@greenbytes.de (2006-10-08): Umbrella issue for
editorial fixes/enhancements. editorial fixes/enhancements.
I.4. media-reg I.4. rfc2048_informative_and_obsolete
In Section 3.7:
Type: change
<http://purl.org/NET/http-errata#media-reg>
derhoermi@gmx.net (2000-09-10): See http://lists.w3.org/Archives/ Type: edit
Public/ietf-http-wg-old/2000SepDec/0013.html.
julian.reschke@greenbytes.de (2006-10-14): Resolve as part of general julian.reschke@greenbytes.de (2006-11-15): Classify RFC2048
update and reclassification of references. ("Multipurpose Internet Mail Extensions (MIME) Part Four:
Registration Procedures") as informative, update to RFC4288,
potentially update the application/http and multipart/byteranges MIME
type registration. Also, in Section 3.7 fix first reference to refer
to RFC2046 (it's about media types in general, not the registration
procedure).
I.5. languagetag I.5. languagetag
In Section 3: In Section 3:
Type: change Type: change
<http://purl.org/NET/http-errata#languagetag> <http://purl.org/NET/http-errata#languagetag>
julian.reschke@greenbytes.de (2006-10-14): See julian.reschke@greenbytes.de (2006-10-14): See
http://purl.org/NET/http-errata#languagetag. http://purl.org/NET/http-errata#languagetag.
julian.reschke@greenbytes.de (2006-10-14): In the meantime RFC3066 julian.reschke@greenbytes.de (2006-10-14): In the meantime RFC3066
has been obsoleted by RFC4646. See also http://lists.w3.org/ has been obsoleted by RFC4646. See also http://lists.w3.org/
Archives/Public/ietf-http-wg/2006OctDec/0001.html. Archives/Public/ietf-http-wg/2006OctDec/0001.html.
I.6. location-fragments I.6. fragment-combination
In Section 14.30: In Section 14.30:
Type: change Type: change
<http://purl.org/NET/http-errata#location-fragments> <http://www.w3.org/Protocols/HTTP/1.1/rfc2616bis/issues/#i43>
fielding@kiwi.ics.uci.edu (1999-08-06): See http://lists.w3.org/ fielding@kiwi.ics.uci.edu (1999-08-06): See
Archives/Public/ietf-http-wg-old/1999MayAug/0103.html. http://lists.w3.org/Archives/Public/ietf-http-wg-old/1999MayAug/0103.
julian.reschke@greenbytes.de (2006-10-16): Fix BNF and add note about julian.reschke@greenbytes.de (2006-10-29): Part of this was fixed in
when it's appropriate to use fragments as suggested in draft 01 (see issue location-fragments). This leaves us with the
http://purl.org/NET/http-errata#location-fragments. This leaves us open issue: _At present, the behavior in the case where there was a
with the open issue: _At present, the behavior in the case where fragment with the original URI, e.g.:
there was a fragment with the original URI, e.g.:
http://host1.example.com/resource1#fragment1 where /resource1 http://host1.example.com/resource1#fragment1 where /resource1
redirects to http://host2.example.com/resource2#fragment2 is redirects to http://host2.example.com/resource2#fragment2 is
'fragment1' discarded? Do you find fragment2 and then find fragment1 'fragment1' discarded? Do you find fragment2 and then find fragment1
within it? We don't have fragment combination rules._. within it? We don't have fragment combination rules._. See also
http://www.w3.org/Protocols/HTTP/1.1/rfc2616bis/issues/#i43.
Index Index
1 1
100 Continue (status code) 67 100 Continue (status code) 66
101 Switching Protocols (status code) 67 101 Switching Protocols (status code) 66
2 2
200 OK (status code) 68 200 OK (status code) 67
201 Created (status code) 68 201 Created (status code) 67
202 Accepted (status code) 68 202 Accepted (status code) 67
203 Non-Authoritative Information (status code) 69 203 Non-Authoritative Information (status code) 68
204 No Content (status code) 69 204 No Content (status code) 68
205 Reset Content (status code) 69 205 Reset Content (status code) 68
206 Partial Content (status code) 70 206 Partial Content (status code) 69
3 3
300 Multiple Choices (status code) 71 300 Multiple Choices (status code) 70
301 Moved Permanently (status code) 71 301 Moved Permanently (status code) 70
302 Found (status code) 72 302 Found (status code) 71
303 See Other (status code) 72 303 See Other (status code) 71
304 Not Modified (status code) 73 304 Not Modified (status code) 72
305 Use Proxy (status code) 73 305 Use Proxy (status code) 72
306 (Unused) (status code) 74 306 (Unused) (status code) 73
307 Temporary Redirect (status code) 74 307 Temporary Redirect (status code) 73
4 4
400 Bad Request (status code) 75 400 Bad Request (status code) 74
401 Unauthorized (status code) 75 401 Unauthorized (status code) 74
402 Payment Required (status code) 75 402 Payment Required (status code) 74
403 Forbidden (status code) 75 403 Forbidden (status code) 74
404 Not Found (status code) 75 404 Not Found (status code) 74
405 Method Not Allowed (status code) 76 405 Method Not Allowed (status code) 75
406 Not Acceptable (status code) 76 406 Not Acceptable (status code) 75
407 Proxy Authentication Required (status code) 76 407 Proxy Authentication Required (status code) 75
408 Request Timeout (status code) 77 408 Request Timeout (status code) 76
409 Conflict (status code) 77 409 Conflict (status code) 76
410 Gone (status code) 77 410 Gone (status code) 76
411 Length Required (status code) 78 411 Length Required (status code) 77
412 Precondition Failed (status code) 78 412 Precondition Failed (status code) 77
413 Request Entity Too Large (status code) 78 413 Request Entity Too Large (status code) 77
414 Request-URI Too Long (status code) 78 414 Request-URI Too Long (status code) 77
415 Unsupported Media Type (status code) 78 415 Unsupported Media Type (status code) 77
416 Requested Range Not Satisfiable (status code) 78 416 Requested Range Not Satisfiable (status code) 77
417 Expectation Failed (status code) 79 417 Expectation Failed (status code) 78
5 5
500 Internal Server Error (status code) 79 500 Internal Server Error (status code) 78
501 Not Implemented (status code) 79 501 Not Implemented (status code) 78
502 Bad Gateway (status code) 79 502 Bad Gateway (status code) 78
503 Service Unavailable (status code) 80 503 Service Unavailable (status code) 79
504 Gateway Timeout (status code) 80 504 Gateway Timeout (status code) 79
505 HTTP Version Not Supported (status code) 80 505 HTTP Version Not Supported (status code) 79
A A
Accept header 111 Accept header 110
Accept-Charset header 113 Accept-Charset header 112
Accept-Encoding header 113 Accept-Encoding header 112
Accept-Language header 115 Accept-Language header 114
Accept-Ranges header 116 Accept-Ranges header 115
age 15 age 14
Age header 116 Age header 115
Allow header 117 Allow header 116
Authorization header 118 Alternates header 188
Authorization header 116
C C
cache 14 cache 13
Cache Directives Cache Directives
max-age 123, 125 max-age 122, 124
max-stale 123 max-stale 122
min-fresh 123 min-fresh 122
must-revalidate 125 must-revalidate 124
no-cache 121 no-cache 120
no-store 121 no-store 120
no-transform 127 no-transform 125
only-if-cached 125 only-if-cached 124
private 120 private 119
proxy-revalidate 126 proxy-revalidate 125
public 120 public 119
s-maxage 122 s-maxage 121
Cache-Control header 118 Cache-Control header 117
cacheable 14 cacheable 13
client 13 client 12
compress 29 compress 28
CONNECT method 66 CONNECT method 65
connection 12 connection 11
Connection header 128 Connection header 127
content negotiation 13 content negotiation 12
Content-Encoding header 129 Content-Base header 188
Content-Language header 130 Content-Encoding header 128
Content-Length header 130 Content-Language header 128
Content-Location header 131 Content-Length header 129
Content-MD5 header 132 Content-Location header 130
Content-Range header 133 Content-MD5 header 131
Content-Type header 135 Content-Range header 132
Content-Type header 134
Content-Version header 188
D D
Date header 136 Date header 134
deflate 29 deflate 28
DELETE method 65 DELETE method 64
downstream 16 Derived-From header 188
downstream 15
E E
entity 12 entity 11
ETag header 137 ETag header 136
Expect header 137 Expect header 136
Expires header 138 Expires header 137
explicit expiration time 15 explicit expiration time 14
F F
first-hand 14 first-hand 13
fresh 15 fresh 14
freshness lifetime 15 freshness lifetime 14
From header 139 From header 138
G G
gateway 14 gateway 13
GET method 62 GET method 61
Grammar Grammar
Accept 111 Accept 110
Accept-Charset 113 Accept-Charset 112
Accept-Encoding 113 Accept-Encoding 112
accept-extension 111 accept-extension 110
Accept-Language 115 Accept-Language 114
accept-params 111 accept-params 110
Accept-Ranges 116 Accept-Ranges 115
acceptable-ranges 116 acceptable-ranges 115
Age 117
age-value 117
Allow 117
ALPHA 21
asctime-date 27
attribute 30
Authorization 118
byte-content-range-spec 133
byte-range-resp-spec 133
byte-range-set 149
byte-range-spec 149
byte-ranges-specifier 149
bytes-unit 36
Cache-Control 119
cache-directive 119
cache-extension 119
cache-request-directive 119
cache-response-directive 119
CHAR 21
charset 28
chunk 31
chunk-data 31
chunk-ext-name 31
chunk-ext-val 31
chunk-extension 31
chunk-size 31
Chunked-Body 31
codings 113
comment 22
Connection 128
connection-token 128
content-coding 29
content-disposition 184
Content-Encoding 129
Content-Language 130
Content-Length 131
Content-Location 131
Content-MD5 132
Content-Range 133
content-range-spec 133
Content-Type 135
CR 21
CRLF 21
ctext 22
CTL 21
Date 136
date1 27
date2 27
date3 27
delta-seconds 27
DIGIT 21
disp-extension-parm 184
disp-extension-token 184
disposition-parm 184
disposition-type 184
entity-body 51
entity-header 51
entity-tag 36
ETag 137
Expect 137
expect-params 137
expectation 137
expectation-extension 137
Expires 138
extension-code 49
extension-header 51
extension-method 43
extension-pragma 148
field-content 39
field-name 39
field-value 39
filename-parm 184
first-byte-pos 149
From 139
general-header 42
generic-message 38
HEX 22
Host 140
HT 21
HTTP-date 27
HTTP-message 38
HTTP-Version 23
http_URL 25
If-Match 140
If-Modified-Since 142
If-None-Match 143
If-Range 144
If-Unmodified-Since 145
instance-length 133
language-range 115
language-tag 35
last-byte-pos 149
last-chunk 31
Last-Modified 145
LF 21
LOALPHA 21
Location 146
LWS 21
Max-Forwards 147
md5-digest 132
media-range 111
media-type 32
message-body 39
message-header 39
Method 43
MIME-Version 181
month 27
OCTET 21
opaque-tag 36
other-range-unit 36
parameter 30
Pragma 148
pragma-directive 148
primary-tag 35
product 34
product-version 34
protocol-name 158
protocol-version 158
Proxy-Authenticate 148
Proxy-Authorization 149
pseudonym 158
qdtext 22
quoted-pair 22
quoted-string 22
qvalue 35
Range 151
range-unit 36
ranges-specifier 149
Reason-Phrase 49
received-by 158
received-protocol 158
Referer 152
Request 43
request-header 46
Request-Line 43
Request-URI 44
Response 47
response-header 50
Retry-After 152
rfc850-date 27
rfc1123-date 27
separators 22
Server 153
SP 21
start-line 38
Status-Code 49
Status-Line 47
subtag 35
subtype 32
suffix-byte-range-spec 150
suffix-length 150
t-codings 153
TE 153
TEXT 21
time 27
token 22
Trailer 154
trailer 31
transfer-coding 30
Transfer-Encoding 155
transfer-extension 30
type 32
UPALPHA 21
Upgrade 155
User-Agent 156
value 30
Vary 157
Via 158
warn-agent 159
warn-code 159
warn-date 159
warn-text 159
Warning 159
warning-value 159
weak 36
weekday 27
wkday 27
WWW-Authenticate 162
gzip 29
H
HEAD method 62
Headers
Accept 111
Accept-Charset 113
Accept-Encoding 113
Accept-Language 115
Accept-Ranges 116
Age 116 Age 116
Allow 117 age-value 116
Authorization 118 Allow 116
ALPHA 20
asctime-date 26
attribute 29
Authorization 117
byte-content-range-spec 132
byte-range-resp-spec 132
byte-range-set 148
byte-range-spec 148
byte-ranges-specifier 148
bytes-unit 35
Cache-Control 118 Cache-Control 118
Connection 128 cache-directive 118
Content-Encoding 129 cache-extension 118
Content-Language 130 cache-request-directive 118
Content-Length 130 cache-response-directive 118
Content-Location 131 CHAR 20
Content-MD5 132 charset 27
Content-Range 133 chunk 30
Content-Type 135 chunk-data 30
Date 136 chunk-ext-name 30
ETag 137 chunk-ext-val 30
Expect 137 chunk-extension 30
Expires 138 chunk-size 30
From 139 Chunked-Body 30
Host 140 codings 112
If-Match 140 comment 21
If-Modified-Since 141 Connection 127
If-None-Match 143 connection-token 127
If-Range 144 content-coding 28
If-Unmodified-Since 145 content-disposition 183
Last-Modified 145 Content-Encoding 128
Location 146 Content-Language 129
Max-Forwards 147 Content-Length 129
Pragma 147 Content-Location 130
Proxy-Authenticate 148 Content-MD5 131
Proxy-Authorization 149 Content-Range 132
content-range-spec 132
Content-Type 134
CR 20
CRLF 20
ctext 21
CTL 20
Date 134
date1 26
date2 26
date3 26
delta-seconds 26
DIGIT 20
disp-extension-parm 183
disp-extension-token 183
disposition-parm 183
disposition-type 183
entity-body 50
entity-header 50
entity-tag 35
ETag 136
Expect 136
expect-params 136
expectation 136
expectation-extension 136
Expires 137
extension-code 48
extension-header 50
extension-method 42
extension-pragma 146
field-content 38
field-name 38
field-value 38
filename-parm 183
first-byte-pos 148
From 138
general-header 41
generic-message 37
HEX 21
Host 138
HT 20
HTTP-date 26
HTTP-message 37
HTTP-Version 22
http_URL 24
If-Match 139
If-Modified-Since 140
If-None-Match 142
If-Range 143
If-Unmodified-Since 144
instance-length 132
language-range 114
language-tag 34
last-byte-pos 148
last-chunk 30
Last-Modified 144
LF 20
LOALPHA 20
Location 145
LWS 20
Max-Forwards 146
md5-digest 131
media-range 110
media-type 31
message-body 38
message-header 38
Method 42
MIME-Version 180
month 26
OCTET 20
opaque-tag 35
other-range-unit 35
parameter 29
Pragma 146
pragma-directive 146
primary-tag 34
product 33
product-version 33
protocol-name 156
protocol-version 156
Proxy-Authenticate 147
Proxy-Authorization 147
pseudonym 156
qdtext 21
quoted-pair 21
quoted-string 21
qvalue 34
Range 149 Range 149
Referer 152 range-unit 35
Retry-After 152 ranges-specifier 148
Server 152 Reason-Phrase 48
TE 153 received-by 156
Trailer 154 received-protocol 156
Transfer-Encoding 155 Referer 150
Upgrade 155 Request 42
User-Agent 156 request-header 45
Vary 157 Request-Line 42
Via 157 Request-URI 43
Warning 159 Response 46
WWW-Authenticate 162 response-header 49
heuristic expiration time 15 Retry-After 151
Host header 140 rfc850-date 26
rfc1123-date 26
separators 21
Server 151
SP 20
start-line 37
Status-Code 48
Status-Line 46
subtag 34
subtype 31
suffix-byte-range-spec 149
suffix-length 149
t-codings 152
TE 152
TEXT 20
time 26
token 21
Trailer 153
trailer 30
transfer-coding 29
Transfer-Encoding 153
transfer-extension 29
type 31
UPALPHA 20
Upgrade 154
User-Agent 155
value 29
Vary 155
Via 156
warn-agent 158
warn-code 158
warn-date 158
warn-text 158
Warning 158
warning-value 158
weak 35
weekday 26
wkday 26
WWW-Authenticate 160
gzip 28
H
HEAD method 61
Headers
Accept 110
Accept-Charset 112
Accept-Encoding 112
Accept-Language 114
Accept-Ranges 115
Age 115
Allow 116
Alternate 188
Authorization 116
Cache-Control 117
Connection 127
Content-Base 188
Content-Encoding 128
Content-Language 128
Content-Length 129
Content-Location 130
Content-MD5 131
Content-Range 132
Content-Type 134
Content-Version 188
Date 134
Derived-From 188
ETag 136
Expect 136
Expires 137
From 138
Host 138
If-Match 139
If-Modified-Since 140
If-None-Match 142
If-Range 143
If-Unmodified-Since 144
Last-Modified 144
Link 188
Location 145
Max-Forwards 146
Pragma 146
Proxy-Authenticate 147
Proxy-Authorization 147
Public 188
Range 148
Referer 150
Retry-After 151
Server 151
TE 152
Trailer 153
Transfer-Encoding 153
Upgrade 154
URI 188
User-Agent 155
Vary 155
Via 156
Warning 158
WWW-Authenticate 160
heuristic expiration time 14
Host header 138
I I
identity 29 identity 28
If-Match header 140 If-Match header 139
If-Modified-Since header 141 If-Modified-Since header 140
If-None-Match header 143 If-None-Match header 142
If-Range header 144 If-Range header 143
If-Unmodified-Since header 145 If-Unmodified-Since header 144
inbound 16 inbound 15
L L
Last-Modified header 145 Last-Modified header 144
Location header 146 Link header 188
LINK method 188
Location header 145
M M
max-age max-age
Cache Directive 123, 125 Cache Directive 122, 124
Max-Forwards header 147 Max-Forwards header 146
max-stale max-stale
Cache Directive 123 Cache Directive 122
message 12 message 11
Methods Methods
CONNECT 66 CONNECT 65
DELETE 65 DELETE 64
GET 62 GET 61
HEAD 62 HEAD 61
OPTIONS 61 LINK 188
POST 63 OPTIONS 60
PUT 64 PATCH 188
TRACE 65 POST 62
PUT 63
TRACE 64
UNLINK 188
min-fresh min-fresh
Cache Directive 123 Cache Directive 122
must-revalidate must-revalidate
Cache Directive 125 Cache Directive 124
N N
no-cache no-cache
Cache Directive 121 Cache Directive 120
no-store no-store
Cache Directive 121 Cache Directive 120
no-transform no-transform
Cache Directive 127 Cache Directive 125
O O
only-if-cached only-if-cached
Cache Directive 125 Cache Directive 124
OPTIONS method 61 OPTIONS method 60
origin server 13 origin server 12
outbound 16 outbound 15
P P
POST method 63 PATCH method 188
Pragma header 147 POST method 62
Pragma header 146
private private
Cache Directive 120 Cache Directive 119
proxy 13 proxy 12
Proxy-Authenticate header 148 Proxy-Authenticate header 147
Proxy-Authorization header 149 Proxy-Authorization header 147
proxy-revalidate proxy-revalidate
Cache Directive 126 Cache Directive 125
public public
Cache Directive 120 Cache Directive 119
PUT method 64 Public header 188
PUT method 63
R R
Range header 149 Range header 148
Referer header 152 Referer header 150
representation 12 representation 11
request 12 request 11
resource 12 resource 11
response 12 response 11
Retry-After header 152 Retry-After header 151
S S
s-maxage s-maxage
Cache Directive 122 Cache Directive 121
semantically transparent 15 semantically transparent 14
server 13 server 12
Server header 152 Server header 151
stale 15 stale 14
Status Codes Status Codes
100 Continue 67 100 Continue 66
101 Switching Protocols 67 101 Switching Protocols 66
200 OK 68 200 OK 67
201 Created 68 201 Created 67
202 Accepted 68 202 Accepted 67
203 Non-Authoritative Information 69 203 Non-Authoritative Information 68
204 No Content 69 204 No Content 68
205 Reset Content 69 205 Reset Content 68
206 Partial Content 70 206 Partial Content 69
300 Multiple Choices 71 300 Multiple Choices 70
301 Moved Permanently 71 301 Moved Permanently 70
302 Found 72 302 Found 71
303 See Other 72 303 See Other 71
304 Not Modified 73 304 Not Modified 72
305 Use Proxy 73 305 Use Proxy 72
306 (Unused) 74 306 (Unused) 73
307 Temporary Redirect 74 307 Temporary Redirect 73
400 Bad Request 75 400 Bad Request 74
401 Unauthorized 75 401 Unauthorized 74
402 Payment Required 75 402 Payment Required 74
403 Forbidden 75 403 Forbidden 74
404 Not Found 75 404 Not Found 74
405 Method Not Allowed 76 405 Method Not Allowed 75
406 Not Acceptable 76 406 Not Acceptable 75
407 Proxy Authentication Required 76 407 Proxy Authentication Required 75
408 Request Timeout 77 408 Request Timeout 76
409 Conflict 77 409 Conflict 76
410 Gone 77 410 Gone 76
411 Length Required 78 411 Length Required 77
412 Precondition Failed 78 412 Precondition Failed 77
413 Request Entity Too Large 78 413 Request Entity Too Large 77
414 Request-URI Too Long 78 414 Request-URI Too Long 77
415 Unsupported Media Type 78 415 Unsupported Media Type 77
416 Requested Range Not Satisfiable 78 416 Requested Range Not Satisfiable 77
417 Expectation Failed 79 417 Expectation Failed 78
500 Internal Server Error 79 500 Internal Server Error 78
501 Not Implemented 79 501 Not Implemented 78
502 Bad Gateway 79 502 Bad Gateway 78
503 Service Unavailable 80 503 Service Unavailable 79
504 Gateway Timeout 80 504 Gateway Timeout 79
505 HTTP Version Not Supported 80 505 HTTP Version Not Supported 79
T T
TE header 153 TE header 152
TRACE method 65 TRACE method 64
Trailer header 154 Trailer header 153
Transfer-Encoding header 155 Transfer-Encoding header 153
tunnel 14 tunnel 13
U U
Upgrade header 155 UNLINK method 188
upstream 16 Upgrade header 154
user agent 13 upstream 15
User-Agent header 156 URI header 188
user agent 12
User-Agent header 155
V V
validator 15 validator 14
variant 13 variant 12
Vary header 157 Vary header 155
Via header 157 Via header 156
W W
Warning header 159 Warning header 158
WWW-Authenticate header 162 WWW-Authenticate header 160
Authors' Addresses Authors' Addresses
Roy T. Fielding Roy T. Fielding
Day Software Day Software
23 Corporate Plaza DR, Suite 215 23 Corporate Plaza DR, Suite 215
Newport Beach, CA 92660 Newport Beach, CA 92660
USA USA
Phone: +1-949-706-5300 Phone: +1-949-706-5300
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