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
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skipping to change at page 1, line 48 skipping to change at page 1, line 48
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This Internet-Draft will expire on April 25, 2007. This Internet-Draft will expire on May 23, 2007.
Copyright Notice Copyright Notice
Copyright (C) The IETF Trust (2006). Copyright (C) The IETF Trust (2006).
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 . . . . . . . . . . . . . . . . . . . . . . . . 12 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 11
1.1. Purpose . . . . . . . . . . . . . . . . . . . . . . . . 12 1.1. Purpose . . . . . . . . . . . . . . . . . . . . . . . . 11
1.2. Requirements . . . . . . . . . . . . . . . . . . . . . . 12 1.2. Requirements . . . . . . . . . . . . . . . . . . . . . . 11
1.3. Terminology . . . . . . . . . . . . . . . . . . . . . . 13 1.3. Terminology . . . . . . . . . . . . . . . . . . . . . . 12
1.4. Overall Operation . . . . . . . . . . . . . . . . . . . 17 1.4. Overall Operation . . . . . . . . . . . . . . . . . . . 16
2. Notational Conventions and Generic Grammar . . . . . . . . . 20 2. Notational Conventions and Generic Grammar . . . . . . . . . 19
2.1. Augmented BNF . . . . . . . . . . . . . . . . . . . . . 20 2.1. Augmented BNF . . . . . . . . . . . . . . . . . . . . . 19
2.2. Basic Rules . . . . . . . . . . . . . . . . . . . . . . 22 2.2. Basic Rules . . . . . . . . . . . . . . . . . . . . . . 21
3. Protocol Parameters . . . . . . . . . . . . . . . . . . . . . 24 3. Protocol Parameters . . . . . . . . . . . . . . . . . . . . . 23
3.1. HTTP Version . . . . . . . . . . . . . . . . . . . . . . 24 3.1. HTTP Version . . . . . . . . . . . . . . . . . . . . . . 23
3.2. Uniform Resource Identifiers . . . . . . . . . . . . . . 25 3.2. Uniform Resource Identifiers . . . . . . . . . . . . . . 24
3.2.1. General Syntax . . . . . . . . . . . . . . . . . . . 25 3.2.1. General Syntax . . . . . . . . . . . . . . . . . . . 24
3.2.2. http URL . . . . . . . . . . . . . . . . . . . . . . 26 3.2.2. http URL . . . . . . . . . . . . . . . . . . . . . . 25
3.2.3. URI Comparison . . . . . . . . . . . . . . . . . . . 26 3.2.3. URI Comparison . . . . . . . . . . . . . . . . . . . 25
3.3. Date/Time Formats . . . . . . . . . . . . . . . . . . . 27 3.3. Date/Time Formats . . . . . . . . . . . . . . . . . . . 26
3.3.1. Full Date . . . . . . . . . . . . . . . . . . . . . 27 3.3.1. Full Date . . . . . . . . . . . . . . . . . . . . . 26
3.3.2. Delta Seconds . . . . . . . . . . . . . . . . . . . 28 3.3.2. Delta Seconds . . . . . . . . . . . . . . . . . . . 27
3.4. Character Sets . . . . . . . . . . . . . . . . . . . . . 28 3.4. Character Sets . . . . . . . . . . . . . . . . . . . . . 27
3.4.1. Missing Charset . . . . . . . . . . . . . . . . . . 29 3.4.1. Missing Charset . . . . . . . . . . . . . . . . . . 28
3.5. Content Codings . . . . . . . . . . . . . . . . . . . . 30 3.5. Content Codings . . . . . . . . . . . . . . . . . . . . 29
3.6. Transfer Codings . . . . . . . . . . . . . . . . . . . . 31 3.6. Transfer Codings . . . . . . . . . . . . . . . . . . . . 30
3.6.1. Chunked Transfer Coding . . . . . . . . . . . . . . 32 3.6.1. Chunked Transfer Coding . . . . . . . . . . . . . . 31
3.7. Media Types . . . . . . . . . . . . . . . . . . . . . . 33 3.7. Media Types . . . . . . . . . . . . . . . . . . . . . . 32
3.7.1. Canonicalization and Text Defaults . . . . . . . . . 34 3.7.1. Canonicalization and Text Defaults . . . . . . . . . 33
3.7.2. Multipart Types . . . . . . . . . . . . . . . . . . 35 3.7.2. Multipart Types . . . . . . . . . . . . . . . . . . 34
3.8. Product Tokens . . . . . . . . . . . . . . . . . . . . . 35 3.8. Product Tokens . . . . . . . . . . . . . . . . . . . . . 34
3.9. Quality Values . . . . . . . . . . . . . . . . . . . . . 36 3.9. Quality Values . . . . . . . . . . . . . . . . . . . . . 35
3.10. Language Tags . . . . . . . . . . . . . . . . . . . . . 36 3.10. Language Tags . . . . . . . . . . . . . . . . . . . . . 35
3.11. Entity Tags . . . . . . . . . . . . . . . . . . . . . . 37 3.11. Entity Tags . . . . . . . . . . . . . . . . . . . . . . 36
3.12. Range Units . . . . . . . . . . . . . . . . . . . . . . 37 3.12. Range Units . . . . . . . . . . . . . . . . . . . . . . 36
4. HTTP Message . . . . . . . . . . . . . . . . . . . . . . . . 39 4. HTTP Message . . . . . . . . . . . . . . . . . . . . . . . . 38
4.1. Message Types . . . . . . . . . . . . . . . . . . . . . 39 4.1. Message Types . . . . . . . . . . . . . . . . . . . . . 38
4.2. Message Headers . . . . . . . . . . . . . . . . . . . . 39 4.2. Message Headers . . . . . . . . . . . . . . . . . . . . 38
4.3. Message Body . . . . . . . . . . . . . . . . . . . . . . 40 4.3. Message Body . . . . . . . . . . . . . . . . . . . . . . 39
4.4. Message Length . . . . . . . . . . . . . . . . . . . . . 41 4.4. Message Length . . . . . . . . . . . . . . . . . . . . . 40
4.5. General Header Fields . . . . . . . . . . . . . . . . . 42 4.5. General Header Fields . . . . . . . . . . . . . . . . . 41
5. Request . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 5. Request . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
5.1. Request-Line . . . . . . . . . . . . . . . . . . . . . . 44 5.1. Request-Line . . . . . . . . . . . . . . . . . . . . . . 43
5.1.1. Method . . . . . . . . . . . . . . . . . . . . . . . 44 5.1.1. Method . . . . . . . . . . . . . . . . . . . . . . . 43
5.1.2. Request-URI . . . . . . . . . . . . . . . . . . . . 45 5.1.2. Request-URI . . . . . . . . . . . . . . . . . . . . 44
5.2. The Resource Identified by a Request . . . . . . . . . . 46 5.2. The Resource Identified by a Request . . . . . . . . . . 45
5.3. Request Header Fields . . . . . . . . . . . . . . . . . 47 5.3. Request Header Fields . . . . . . . . . . . . . . . . . 46
6. Response . . . . . . . . . . . . . . . . . . . . . . . . . . 48 6. Response . . . . . . . . . . . . . . . . . . . . . . . . . . 47
6.1. Status-Line . . . . . . . . . . . . . . . . . . . . . . 48 6.1. Status-Line . . . . . . . . . . . . . . . . . . . . . . 47
6.1.1. Status Code and Reason Phrase . . . . . . . . . . . 48 6.1.1. Status Code and Reason Phrase . . . . . . . . . . . 47
6.2. Response Header Fields . . . . . . . . . . . . . . . . . 51 6.2. Response Header Fields . . . . . . . . . . . . . . . . . 50
7. Entity . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 7. Entity . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
7.1. Entity Header Fields . . . . . . . . . . . . . . . . . . 52 7.1. Entity Header Fields . . . . . . . . . . . . . . . . . . 51
7.2. Entity Body . . . . . . . . . . . . . . . . . . . . . . 52 7.2. Entity Body . . . . . . . . . . . . . . . . . . . . . . 51
7.2.1. Type . . . . . . . . . . . . . . . . . . . . . . . . 53 7.2.1. Type . . . . . . . . . . . . . . . . . . . . . . . . 52
7.2.2. Entity Length . . . . . . . . . . . . . . . . . . . 53 7.2.2. Entity Length . . . . . . . . . . . . . . . . . . . 52
8. Connections . . . . . . . . . . . . . . . . . . . . . . . . . 54 8. Connections . . . . . . . . . . . . . . . . . . . . . . . . . 53
8.1. Persistent Connections . . . . . . . . . . . . . . . . . 54 8.1. Persistent Connections . . . . . . . . . . . . . . . . . 53
8.1.1. Purpose . . . . . . . . . . . . . . . . . . . . . . 54 8.1.1. Purpose . . . . . . . . . . . . . . . . . . . . . . 53
8.1.2. Overall Operation . . . . . . . . . . . . . . . . . 54 8.1.2. Overall Operation . . . . . . . . . . . . . . . . . 53
8.1.3. Proxy Servers . . . . . . . . . . . . . . . . . . . 56 8.1.3. Proxy Servers . . . . . . . . . . . . . . . . . . . 55
8.1.4. Practical Considerations . . . . . . . . . . . . . . 56 8.1.4. Practical Considerations . . . . . . . . . . . . . . 55
8.2. Message Transmission Requirements . . . . . . . . . . . 57 8.2. Message Transmission Requirements . . . . . . . . . . . 56
8.2.1. Persistent Connections and Flow Control . . . . . . 57 8.2.1. Persistent Connections and Flow Control . . . . . . 56
8.2.2. Monitoring Connections for Error Status Messages . . 57 8.2.2. Monitoring Connections for Error Status Messages . . 56
8.2.3. Use of the 100 (Continue) Status . . . . . . . . . . 58 8.2.3. Use of the 100 (Continue) Status . . . . . . . . . . 57
8.2.4. Client Behavior if Server Prematurely Closes 8.2.4. Client Behavior if Server Prematurely Closes
Connection . . . . . . . . . . . . . . . . . . . . . 60 Connection . . . . . . . . . . . . . . . . . . . . . 59
9. Method Definitions . . . . . . . . . . . . . . . . . . . . . 61 9. Method Definitions . . . . . . . . . . . . . . . . . . . . . 60
9.1. Safe and Idempotent Methods . . . . . . . . . . . . . . 61 9.1. Safe and Idempotent Methods . . . . . . . . . . . . . . 60
9.1.1. Safe Methods . . . . . . . . . . . . . . . . . . . . 61 9.1.1. Safe Methods . . . . . . . . . . . . . . . . . . . . 60
9.1.2. Idempotent Methods . . . . . . . . . . . . . . . . . 61 9.1.2. Idempotent Methods . . . . . . . . . . . . . . . . . 60
9.2. OPTIONS . . . . . . . . . . . . . . . . . . . . . . . . 62 9.2. OPTIONS . . . . . . . . . . . . . . . . . . . . . . . . 61
9.3. GET . . . . . . . . . . . . . . . . . . . . . . . . . . 63 9.3. GET . . . . . . . . . . . . . . . . . . . . . . . . . . 62
9.4. HEAD . . . . . . . . . . . . . . . . . . . . . . . . . . 63 9.4. HEAD . . . . . . . . . . . . . . . . . . . . . . . . . . 62
9.5. POST . . . . . . . . . . . . . . . . . . . . . . . . . . 64 9.5. POST . . . . . . . . . . . . . . . . . . . . . . . . . . 63
9.6. PUT . . . . . . . . . . . . . . . . . . . . . . . . . . 65 9.6. PUT . . . . . . . . . . . . . . . . . . . . . . . . . . 64
9.7. DELETE . . . . . . . . . . . . . . . . . . . . . . . . . 66 9.7. DELETE . . . . . . . . . . . . . . . . . . . . . . . . . 65
9.8. TRACE . . . . . . . . . . . . . . . . . . . . . . . . . 66 9.8. TRACE . . . . . . . . . . . . . . . . . . . . . . . . . 65
9.9. CONNECT . . . . . . . . . . . . . . . . . . . . . . . . 67 9.9. CONNECT . . . . . . . . . . . . . . . . . . . . . . . . 66
10. Status Code Definitions . . . . . . . . . . . . . . . . . . . 68 10. Status Code Definitions . . . . . . . . . . . . . . . . . . . 67
10.1. Informational 1xx . . . . . . . . . . . . . . . . . . . 68 10.1. Informational 1xx . . . . . . . . . . . . . . . . . . . 67
10.1.1. 100 Continue . . . . . . . . . . . . . . . . . . . . 68 10.1.1. 100 Continue . . . . . . . . . . . . . . . . . . . . 67
10.1.2. 101 Switching Protocols . . . . . . . . . . . . . . 68 10.1.2. 101 Switching Protocols . . . . . . . . . . . . . . 67
10.2. Successful 2xx . . . . . . . . . . . . . . . . . . . . . 69 10.2. Successful 2xx . . . . . . . . . . . . . . . . . . . . . 68
10.2.1. 200 OK . . . . . . . . . . . . . . . . . . . . . . . 69 10.2.1. 200 OK . . . . . . . . . . . . . . . . . . . . . . . 68
10.2.2. 201 Created . . . . . . . . . . . . . . . . . . . . 69 10.2.2. 201 Created . . . . . . . . . . . . . . . . . . . . 68
10.2.3. 202 Accepted . . . . . . . . . . . . . . . . . . . . 69 10.2.3. 202 Accepted . . . . . . . . . . . . . . . . . . . . 68
10.2.4. 203 Non-Authoritative Information . . . . . . . . . 70 10.2.4. 203 Non-Authoritative Information . . . . . . . . . 69
10.2.5. 204 No Content . . . . . . . . . . . . . . . . . . . 70 10.2.5. 204 No Content . . . . . . . . . . . . . . . . . . . 69
10.2.6. 205 Reset Content . . . . . . . . . . . . . . . . . 70 10.2.6. 205 Reset Content . . . . . . . . . . . . . . . . . 69
10.2.7. 206 Partial Content . . . . . . . . . . . . . . . . 71 10.2.7. 206 Partial Content . . . . . . . . . . . . . . . . 70
10.3. Redirection 3xx . . . . . . . . . . . . . . . . . . . . 71 10.3. Redirection 3xx . . . . . . . . . . . . . . . . . . . . 70
10.3.1. 300 Multiple Choices . . . . . . . . . . . . . . . . 72 10.3.1. 300 Multiple Choices . . . . . . . . . . . . . . . . 71
10.3.2. 301 Moved Permanently . . . . . . . . . . . . . . . 72 10.3.2. 301 Moved Permanently . . . . . . . . . . . . . . . 71
10.3.3. 302 Found . . . . . . . . . . . . . . . . . . . . . 73 10.3.3. 302 Found . . . . . . . . . . . . . . . . . . . . . 72
10.3.4. 303 See Other . . . . . . . . . . . . . . . . . . . 73 10.3.4. 303 See Other . . . . . . . . . . . . . . . . . . . 72
10.3.5. 304 Not Modified . . . . . . . . . . . . . . . . . . 74 10.3.5. 304 Not Modified . . . . . . . . . . . . . . . . . . 73
10.3.6. 305 Use Proxy . . . . . . . . . . . . . . . . . . . 74 10.3.6. 305 Use Proxy . . . . . . . . . . . . . . . . . . . 73
10.3.7. 306 (Unused) . . . . . . . . . . . . . . . . . . . . 75 10.3.7. 306 (Unused) . . . . . . . . . . . . . . . . . . . . 74
10.3.8. 307 Temporary Redirect . . . . . . . . . . . . . . . 75 10.3.8. 307 Temporary Redirect . . . . . . . . . . . . . . . 74
10.4. Client Error 4xx . . . . . . . . . . . . . . . . . . . . 75 10.4. Client Error 4xx . . . . . . . . . . . . . . . . . . . . 74
10.4.1. 400 Bad Request . . . . . . . . . . . . . . . . . . 76 10.4.1. 400 Bad Request . . . . . . . . . . . . . . . . . . 75
10.4.2. 401 Unauthorized . . . . . . . . . . . . . . . . . . 76 10.4.2. 401 Unauthorized . . . . . . . . . . . . . . . . . . 75
10.4.3. 402 Payment Required . . . . . . . . . . . . . . . . 76 10.4.3. 402 Payment Required . . . . . . . . . . . . . . . . 75
10.4.4. 403 Forbidden . . . . . . . . . . . . . . . . . . . 76 10.4.4. 403 Forbidden . . . . . . . . . . . . . . . . . . . 75
10.4.5. 404 Not Found . . . . . . . . . . . . . . . . . . . 76 10.4.5. 404 Not Found . . . . . . . . . . . . . . . . . . . 75
10.4.6. 405 Method Not Allowed . . . . . . . . . . . . . . . 77 10.4.6. 405 Method Not Allowed . . . . . . . . . . . . . . . 76
10.4.7. 406 Not Acceptable . . . . . . . . . . . . . . . . . 77 10.4.7. 406 Not Acceptable . . . . . . . . . . . . . . . . . 76
10.4.8. 407 Proxy Authentication Required . . . . . . . . . 77 10.4.8. 407 Proxy Authentication Required . . . . . . . . . 76
10.4.9. 408 Request Timeout . . . . . . . . . . . . . . . . 78 10.4.9. 408 Request Timeout . . . . . . . . . . . . . . . . 77
10.4.10. 409 Conflict . . . . . . . . . . . . . . . . . . . . 78 10.4.10. 409 Conflict . . . . . . . . . . . . . . . . . . . . 77
10.4.11. 410 Gone . . . . . . . . . . . . . . . . . . . . . . 78 10.4.11. 410 Gone . . . . . . . . . . . . . . . . . . . . . . 77
10.4.12. 411 Length Required . . . . . . . . . . . . . . . . 79 10.4.12. 411 Length Required . . . . . . . . . . . . . . . . 78
10.4.13. 412 Precondition Failed . . . . . . . . . . . . . . 79 10.4.13. 412 Precondition Failed . . . . . . . . . . . . . . 78
10.4.14. 413 Request Entity Too Large . . . . . . . . . . . . 79 10.4.14. 413 Request Entity Too Large . . . . . . . . . . . . 78
10.4.15. 414 Request-URI Too Long . . . . . . . . . . . . . . 79 10.4.15. 414 Request-URI Too Long . . . . . . . . . . . . . . 78
10.4.16. 415 Unsupported Media Type . . . . . . . . . . . . . 79 10.4.16. 415 Unsupported Media Type . . . . . . . . . . . . . 78
10.4.17. 416 Requested Range Not Satisfiable . . . . . . . . 79 10.4.17. 416 Requested Range Not Satisfiable . . . . . . . . 78
10.4.18. 417 Expectation Failed . . . . . . . . . . . . . . . 80 10.4.18. 417 Expectation Failed . . . . . . . . . . . . . . . 79
10.5. Server Error 5xx . . . . . . . . . . . . . . . . . . . . 80 10.5. Server Error 5xx . . . . . . . . . . . . . . . . . . . . 79
10.5.1. 500 Internal Server Error . . . . . . . . . . . . . 80 10.5.1. 500 Internal Server Error . . . . . . . . . . . . . 79
10.5.2. 501 Not Implemented . . . . . . . . . . . . . . . . 80 10.5.2. 501 Not Implemented . . . . . . . . . . . . . . . . 79
10.5.3. 502 Bad Gateway . . . . . . . . . . . . . . . . . . 80 10.5.3. 502 Bad Gateway . . . . . . . . . . . . . . . . . . 79
10.5.4. 503 Service Unavailable . . . . . . . . . . . . . . 81 10.5.4. 503 Service Unavailable . . . . . . . . . . . . . . 80
10.5.5. 504 Gateway Timeout . . . . . . . . . . . . . . . . 81 10.5.5. 504 Gateway Timeout . . . . . . . . . . . . . . . . 80
10.5.6. 505 HTTP Version Not Supported . . . . . . . . . . . 81 10.5.6. 505 HTTP Version Not Supported . . . . . . . . . . . 80
11. Access Authentication . . . . . . . . . . . . . . . . . . . . 82 11. Access Authentication . . . . . . . . . . . . . . . . . . . . 81
12. Content Negotiation . . . . . . . . . . . . . . . . . . . . . 83 12. Content Negotiation . . . . . . . . . . . . . . . . . . . . . 82
12.1. Server-driven Negotiation . . . . . . . . . . . . . . . 83 12.1. Server-driven Negotiation . . . . . . . . . . . . . . . 82
12.2. Agent-driven Negotiation . . . . . . . . . . . . . . . . 84 12.2. Agent-driven Negotiation . . . . . . . . . . . . . . . . 83
12.3. Transparent Negotiation . . . . . . . . . . . . . . . . 85 12.3. Transparent Negotiation . . . . . . . . . . . . . . . . 84
13. Caching in HTTP . . . . . . . . . . . . . . . . . . . . . . . 86 13. Caching in HTTP . . . . . . . . . . . . . . . . . . . . . . . 85
13.1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87 13.1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
13.1.1. Cache Correctness . . . . . . . . . . . . . . . . . 87 13.1.1. Cache Correctness . . . . . . . . . . . . . . . . . 86
13.1.2. Warnings . . . . . . . . . . . . . . . . . . . . . . 88 13.1.2. Warnings . . . . . . . . . . . . . . . . . . . . . . 87
13.1.3. Cache-control Mechanisms . . . . . . . . . . . . . . 89 13.1.3. Cache-control Mechanisms . . . . . . . . . . . . . . 88
13.1.4. Explicit User Agent Warnings . . . . . . . . . . . . 89 13.1.4. Explicit User Agent Warnings . . . . . . . . . . . . 88
13.1.5. Exceptions to the Rules and Warnings . . . . . . . . 90 13.1.5. Exceptions to the Rules and Warnings . . . . . . . . 89
13.1.6. Client-controlled Behavior . . . . . . . . . . . . . 90 13.1.6. Client-controlled Behavior . . . . . . . . . . . . . 89
13.2. Expiration Model . . . . . . . . . . . . . . . . . . . . 91 13.2. Expiration Model . . . . . . . . . . . . . . . . . . . . 90
13.2.1. Server-Specified Expiration . . . . . . . . . . . . 91 13.2.1. Server-Specified Expiration . . . . . . . . . . . . 90
13.2.2. Heuristic Expiration . . . . . . . . . . . . . . . . 91 13.2.2. Heuristic Expiration . . . . . . . . . . . . . . . . 90
13.2.3. Age Calculations . . . . . . . . . . . . . . . . . . 92 13.2.3. Age Calculations . . . . . . . . . . . . . . . . . . 91
13.2.4. Expiration Calculations . . . . . . . . . . . . . . 94 13.2.4. Expiration Calculations . . . . . . . . . . . . . . 93
13.2.5. Disambiguating Expiration Values . . . . . . . . . . 95 13.2.5. Disambiguating Expiration Values . . . . . . . . . . 94
13.2.6. Disambiguating Multiple Responses . . . . . . . . . 96 13.2.6. Disambiguating Multiple Responses . . . . . . . . . 95
13.3. Validation Model . . . . . . . . . . . . . . . . . . . . 96 13.3. Validation Model . . . . . . . . . . . . . . . . . . . . 95
13.3.1. Last-Modified Dates . . . . . . . . . . . . . . . . 97 13.3.1. Last-Modified Dates . . . . . . . . . . . . . . . . 96
13.3.2. Entity Tag Cache Validators . . . . . . . . . . . . 97 13.3.2. Entity Tag Cache Validators . . . . . . . . . . . . 96
13.3.3. Weak and Strong Validators . . . . . . . . . . . . . 98 13.3.3. Weak and Strong Validators . . . . . . . . . . . . . 97
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 . . . . . . . . . . . . . . . . 100 Last-Modified Dates . . . . . . . . . . . . . . . . 99
13.3.5. Non-validating Conditionals . . . . . . . . . . . . 102 13.3.5. Non-validating Conditionals . . . . . . . . . . . . 101
13.4. Response Cacheability . . . . . . . . . . . . . . . . . 102 13.4. Response Cacheability . . . . . . . . . . . . . . . . . 101
13.5. Constructing Responses From Caches . . . . . . . . . . . 103 13.5. Constructing Responses From Caches . . . . . . . . . . . 102
13.5.1. End-to-end and Hop-by-hop Headers . . . . . . . . . 103 13.5.1. End-to-end and Hop-by-hop Headers . . . . . . . . . 102
13.5.2. Non-modifiable Headers . . . . . . . . . . . . . . . 104 13.5.2. Non-modifiable Headers . . . . . . . . . . . . . . . 103
13.5.3. Combining Headers . . . . . . . . . . . . . . . . . 105 13.5.3. Combining Headers . . . . . . . . . . . . . . . . . 104
13.5.4. Combining Byte Ranges . . . . . . . . . . . . . . . 106 13.5.4. Combining Byte Ranges . . . . . . . . . . . . . . . 105
13.6. Caching Negotiated Responses . . . . . . . . . . . . . . 107 13.6. Caching Negotiated Responses . . . . . . . . . . . . . . 106
13.7. Shared and Non-Shared Caches . . . . . . . . . . . . . . 108 13.7. Shared and Non-Shared Caches . . . . . . . . . . . . . . 107
13.8. Errors or Incomplete Response Cache Behavior . . . . . . 108 13.8. Errors or Incomplete Response Cache Behavior . . . . . . 107
13.9. Side Effects of GET and HEAD . . . . . . . . . . . . . . 109 13.9. Side Effects of GET and HEAD . . . . . . . . . . . . . . 108
13.10. Invalidation After Updates or Deletions . . . . . . . . 109 13.10. Invalidation After Updates or Deletions . . . . . . . . 108
13.11. Write-Through Mandatory . . . . . . . . . . . . . . . . 110 13.11. Write-Through Mandatory . . . . . . . . . . . . . . . . 109
13.12. Cache Replacement . . . . . . . . . . . . . . . . . . . 110 13.12. Cache Replacement . . . . . . . . . . . . . . . . . . . 109
13.13. History Lists . . . . . . . . . . . . . . . . . . . . . 111 13.13. History Lists . . . . . . . . . . . . . . . . . . . . . 110
14. Header Field Definitions . . . . . . . . . . . . . . . . . . 112 14. Header Field Definitions . . . . . . . . . . . . . . . . . . 111
14.1. Accept . . . . . . . . . . . . . . . . . . . . . . . . . 112 14.1. Accept . . . . . . . . . . . . . . . . . . . . . . . . . 111
14.2. Accept-Charset . . . . . . . . . . . . . . . . . . . . . 114 14.2. Accept-Charset . . . . . . . . . . . . . . . . . . . . . 113
14.3. Accept-Encoding . . . . . . . . . . . . . . . . . . . . 114 14.3. Accept-Encoding . . . . . . . . . . . . . . . . . . . . 113
14.4. Accept-Language . . . . . . . . . . . . . . . . . . . . 116 14.4. Accept-Language . . . . . . . . . . . . . . . . . . . . 115
14.5. Accept-Ranges . . . . . . . . . . . . . . . . . . . . . 117 14.5. Accept-Ranges . . . . . . . . . . . . . . . . . . . . . 116
14.6. Age . . . . . . . . . . . . . . . . . . . . . . . . . . 117 14.6. Age . . . . . . . . . . . . . . . . . . . . . . . . . . 116
14.7. Allow . . . . . . . . . . . . . . . . . . . . . . . . . 118 14.7. Allow . . . . . . . . . . . . . . . . . . . . . . . . . 117
14.8. Authorization . . . . . . . . . . . . . . . . . . . . . 119 14.8. Authorization . . . . . . . . . . . . . . . . . . . . . 117
14.9. Cache-Control . . . . . . . . . . . . . . . . . . . . . 119 14.9. Cache-Control . . . . . . . . . . . . . . . . . . . . . 118
14.9.1. What is Cacheable . . . . . . . . . . . . . . . . . 121 14.9.1. What is Cacheable . . . . . . . . . . . . . . . . . 120
14.9.2. What May be Stored by Caches . . . . . . . . . . . . 122 14.9.2. What May be Stored by Caches . . . . . . . . . . . . 121
14.9.3. Modifications of the Basic Expiration Mechanism . . 123 14.9.3. Modifications of the Basic Expiration Mechanism . . 122
14.9.4. Cache Revalidation and Reload Controls . . . . . . . 125 14.9.4. Cache Revalidation and Reload Controls . . . . . . . 124
14.9.5. No-Transform Directive . . . . . . . . . . . . . . . 128 14.9.5. No-Transform Directive . . . . . . . . . . . . . . . 126
14.9.6. Cache Control Extensions . . . . . . . . . . . . . . 128 14.9.6. Cache Control Extensions . . . . . . . . . . . . . . 127
14.10. Connection . . . . . . . . . . . . . . . . . . . . . . . 129 14.10. Connection . . . . . . . . . . . . . . . . . . . . . . . 128
14.11. Content-Encoding . . . . . . . . . . . . . . . . . . . . 130 14.11. Content-Encoding . . . . . . . . . . . . . . . . . . . . 129
14.12. Content-Language . . . . . . . . . . . . . . . . . . . . 131 14.12. Content-Language . . . . . . . . . . . . . . . . . . . . 129
14.13. Content-Length . . . . . . . . . . . . . . . . . . . . . 131 14.13. Content-Length . . . . . . . . . . . . . . . . . . . . . 130
14.14. Content-Location . . . . . . . . . . . . . . . . . . . . 132 14.14. Content-Location . . . . . . . . . . . . . . . . . . . . 131
14.15. Content-MD5 . . . . . . . . . . . . . . . . . . . . . . 133 14.15. Content-MD5 . . . . . . . . . . . . . . . . . . . . . . 132
14.16. Content-Range . . . . . . . . . . . . . . . . . . . . . 134 14.16. Content-Range . . . . . . . . . . . . . . . . . . . . . 133
14.17. Content-Type . . . . . . . . . . . . . . . . . . . . . . 136 14.17. Content-Type . . . . . . . . . . . . . . . . . . . . . . 135
14.18. Date . . . . . . . . . . . . . . . . . . . . . . . . . . 137 14.18. Date . . . . . . . . . . . . . . . . . . . . . . . . . . 135
14.18.1. Clockless Origin Server Operation . . . . . . . . . 138 14.18.1. Clockless Origin Server Operation . . . . . . . . . 136
14.19. ETag . . . . . . . . . . . . . . . . . . . . . . . . . . 138 14.19. ETag . . . . . . . . . . . . . . . . . . . . . . . . . . 137
14.20. Expect . . . . . . . . . . . . . . . . . . . . . . . . . 138 14.20. Expect . . . . . . . . . . . . . . . . . . . . . . . . . 137
14.21. Expires . . . . . . . . . . . . . . . . . . . . . . . . 139 14.21. Expires . . . . . . . . . . . . . . . . . . . . . . . . 138
14.22. From . . . . . . . . . . . . . . . . . . . . . . . . . . 140 14.22. From . . . . . . . . . . . . . . . . . . . . . . . . . . 139
14.23. Host . . . . . . . . . . . . . . . . . . . . . . . . . . 141 14.23. Host . . . . . . . . . . . . . . . . . . . . . . . . . . 139
14.24. If-Match . . . . . . . . . . . . . . . . . . . . . . . . 141 14.24. If-Match . . . . . . . . . . . . . . . . . . . . . . . . 140
14.25. If-Modified-Since . . . . . . . . . . . . . . . . . . . 142 14.25. If-Modified-Since . . . . . . . . . . . . . . . . . . . 141
14.26. If-None-Match . . . . . . . . . . . . . . . . . . . . . 144 14.26. If-None-Match . . . . . . . . . . . . . . . . . . . . . 143
14.27. If-Range . . . . . . . . . . . . . . . . . . . . . . . . 145 14.27. If-Range . . . . . . . . . . . . . . . . . . . . . . . . 144
14.28. If-Unmodified-Since . . . . . . . . . . . . . . . . . . 146 14.28. If-Unmodified-Since . . . . . . . . . . . . . . . . . . 145
14.29. Last-Modified . . . . . . . . . . . . . . . . . . . . . 146 14.29. Last-Modified . . . . . . . . . . . . . . . . . . . . . 145
14.30. Location . . . . . . . . . . . . . . . . . . . . . . . . 147 14.30. Location . . . . . . . . . . . . . . . . . . . . . . . . 146
14.31. Max-Forwards . . . . . . . . . . . . . . . . . . . . . . 148 14.31. Max-Forwards . . . . . . . . . . . . . . . . . . . . . . 147
14.32. Pragma . . . . . . . . . . . . . . . . . . . . . . . . . 148 14.32. Pragma . . . . . . . . . . . . . . . . . . . . . . . . . 147
14.33. Proxy-Authenticate . . . . . . . . . . . . . . . . . . . 149 14.33. Proxy-Authenticate . . . . . . . . . . . . . . . . . . . 148
14.34. Proxy-Authorization . . . . . . . . . . . . . . . . . . 150 14.34. Proxy-Authorization . . . . . . . . . . . . . . . . . . 148
14.35. Range . . . . . . . . . . . . . . . . . . . . . . . . . 150 14.35. Range . . . . . . . . . . . . . . . . . . . . . . . . . 149
14.35.1. Byte Ranges . . . . . . . . . . . . . . . . . . . . 150 14.35.1. Byte Ranges . . . . . . . . . . . . . . . . . . . . 149
14.35.2. Range Retrieval Requests . . . . . . . . . . . . . . 152 14.35.2. Range Retrieval Requests . . . . . . . . . . . . . . 150
14.36. Referer . . . . . . . . . . . . . . . . . . . . . . . . 153 14.36. Referer . . . . . . . . . . . . . . . . . . . . . . . . 151
14.37. Retry-After . . . . . . . . . . . . . . . . . . . . . . 153 14.37. Retry-After . . . . . . . . . . . . . . . . . . . . . . 152
14.38. Server . . . . . . . . . . . . . . . . . . . . . . . . . 153 14.38. Server . . . . . . . . . . . . . . . . . . . . . . . . . 152
14.39. TE . . . . . . . . . . . . . . . . . . . . . . . . . . . 154 14.39. TE . . . . . . . . . . . . . . . . . . . . . . . . . . . 153
14.40. Trailer . . . . . . . . . . . . . . . . . . . . . . . . 155 14.40. Trailer . . . . . . . . . . . . . . . . . . . . . . . . 154
14.41. Transfer-Encoding . . . . . . . . . . . . . . . . . . . 156 14.41. Transfer-Encoding . . . . . . . . . . . . . . . . . . . 154
14.42. Upgrade . . . . . . . . . . . . . . . . . . . . . . . . 156 14.42. Upgrade . . . . . . . . . . . . . . . . . . . . . . . . 155
14.43. User-Agent . . . . . . . . . . . . . . . . . . . . . . . 157 14.43. User-Agent . . . . . . . . . . . . . . . . . . . . . . . 156
14.44. Vary . . . . . . . . . . . . . . . . . . . . . . . . . . 158 14.44. Vary . . . . . . . . . . . . . . . . . . . . . . . . . . 156
14.45. Via . . . . . . . . . . . . . . . . . . . . . . . . . . 158 14.45. Via . . . . . . . . . . . . . . . . . . . . . . . . . . 157
14.46. Warning . . . . . . . . . . . . . . . . . . . . . . . . 160 14.46. Warning . . . . . . . . . . . . . . . . . . . . . . . . 159
14.47. WWW-Authenticate . . . . . . . . . . . . . . . . . . . . 163 14.47. WWW-Authenticate . . . . . . . . . . . . . . . . . . . . 161
15. Security Considerations . . . . . . . . . . . . . . . . . . . 164 15. Security Considerations . . . . . . . . . . . . . . . . . . . 162
15.1. Personal Information . . . . . . . . . . . . . . . . . . 164 15.1. Personal Information . . . . . . . . . . . . . . . . . . 162
15.1.1. Abuse of Server Log Information . . . . . . . . . . 164 15.1.1. Abuse of Server Log Information . . . . . . . . . . 162
15.1.2. Transfer of Sensitive Information . . . . . . . . . 164 15.1.2. Transfer of Sensitive Information . . . . . . . . . 162
15.1.3. Encoding Sensitive Information in URI's . . . . . . 165 15.1.3. Encoding Sensitive Information in URI's . . . . . . 163
15.1.4. Privacy Issues Connected to Accept Headers . . . . . 166 15.1.4. Privacy Issues Connected to Accept Headers . . . . . 164
15.2. Attacks Based On File and Path Names . . . . . . . . . . 166 15.2. Attacks Based On File and Path Names . . . . . . . . . . 164
15.3. DNS Spoofing . . . . . . . . . . . . . . . . . . . . . . 167 15.3. DNS Spoofing . . . . . . . . . . . . . . . . . . . . . . 165
15.4. Location Headers and Spoofing . . . . . . . . . . . . . 167 15.4. Location Headers and Spoofing . . . . . . . . . . . . . 165
15.5. Content-Disposition Issues . . . . . . . . . . . . . . . 168 15.5. Content-Disposition Issues . . . . . . . . . . . . . . . 166
15.6. Authentication Credentials and Idle Clients . . . . . . 168 15.6. Authentication Credentials and Idle Clients . . . . . . 166
15.7. Proxies and Caching . . . . . . . . . . . . . . . . . . 168 15.7. Proxies and Caching . . . . . . . . . . . . . . . . . . 166
15.7.1. Denial of Service Attacks on Proxies . . . . . . . . 169 15.7.1. Denial of Service Attacks on Proxies . . . . . . . . 167
16. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 170 16. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 168
16.1. (RFC2616) . . . . . . . . . . . . . . . . . . . . . . . 170 16.1. (RFC2616) . . . . . . . . . . . . . . . . . . . . . . . 168
16.2. (This Document) . . . . . . . . . . . . . . . . . . . . 171 16.2. (This Document) . . . . . . . . . . . . . . . . . . . . 169
17. References . . . . . . . . . . . . . . . . . . . . . . . . . 172 17. References . . . . . . . . . . . . . . . . . . . . . . . . . 170
17.1. References . . . . . . . . . . . . . . . . . . . . . . . 172 17.1. References . . . . . . . . . . . . . . . . . . . . . . . 170
17.2. Informative References . . . . . . . . . . . . . . . . . 175 17.2. Informative References . . . . . . . . . . . . . . . . . 174
Appendix A. Internet Media Type message/http and Appendix A. Internet Media Type message/http and
application/http . . . . . . . . . . . . . . . . . . 177 application/http . . . . . . . . . . . . . . . . . . 176
Appendix B. Internet Media Type multipart/byteranges . . . . . . 179 Appendix B. Internet Media Type multipart/byteranges . . . . . . 178
Appendix C. Tolerant Applications . . . . . . . . . . . . . . . 181 Appendix C. Tolerant Applications . . . . . . . . . . . . . . . 180
Appendix D. Differences Between HTTP Entities and RFC 2045 Appendix D. Differences Between HTTP Entities and RFC 2045
Entities . . . . . . . . . . . . . . . . . . . . . . 182 Entities . . . . . . . . . . . . . . . . . . . . . . 181
D.1. MIME-Version . . . . . . . . . . . . . . . . . . . . . . 182 D.1. MIME-Version . . . . . . . . . . . . . . . . . . . . . . 181
D.2. Conversion to Canonical Form . . . . . . . . . . . . . . 182 D.2. Conversion to Canonical Form . . . . . . . . . . . . . . 181
D.3. Conversion of Date Formats . . . . . . . . . . . . . . . 183 D.3. Conversion of Date Formats . . . . . . . . . . . . . . . 182
D.4. Introduction of Content-Encoding . . . . . . . . . . . . 183 D.4. Introduction of Content-Encoding . . . . . . . . . . . . 182
D.5. No Content-Transfer-Encoding . . . . . . . . . . . . . . 183 D.5. No Content-Transfer-Encoding . . . . . . . . . . . . . . 182
D.6. Introduction of Transfer-Encoding . . . . . . . . . . . 184 D.6. Introduction of Transfer-Encoding . . . . . . . . . . . 183
D.7. MHTML and Line Length Limitations . . . . . . . . . . . 184 D.7. MHTML and Line Length Limitations . . . . . . . . . . . 183
Appendix E. Additional Features . . . . . . . . . . . . . . . . 185 Appendix E. Additional Features . . . . . . . . . . . . . . . . 184
E.1. Content-Disposition . . . . . . . . . . . . . . . . . . 185 E.1. Content-Disposition . . . . . . . . . . . . . . . . . . 184
Appendix F. Compatibility with Previous Versions . . . . . . . . 186 Appendix F. Compatibility with Previous Versions . . . . . . . . 185
F.1. Changes from HTTP/1.0 . . . . . . . . . . . . . . . . . 186 F.1. Changes from HTTP/1.0 . . . . . . . . . . . . . . . . . 185
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 . . . . . . . . . . . . . . . 186 Conserve IP Addresses . . . . . . . . . . . . . . . 185
F.2. Compatibility with HTTP/1.0 Persistent Connections . . . 187 F.2. Compatibility with HTTP/1.0 Persistent Connections . . . 186
F.3. Changes from RFC 2068 . . . . . . . . . . . . . . . . . 188 F.3. Changes from RFC 2068 . . . . . . . . . . . . . . . . . 187
F.4. Changes from RFC 2616 . . . . . . . . . . . . . . . . . 190 F.4. Changes from RFC 2616 . . . . . . . . . . . . . . . . . 189
Appendix G. Change Log (to be removed by RFC Editor before Appendix G. Change Log (to be removed by RFC Editor before
publication) . . . . . . . . . . . . . . . . . . . . 192 publication) . . . . . . . . . . . . . . . . . . . . 191
G.1. Since RFC2616 . . . . . . . . . . . . . . . . . . . . . 192 G.1. Since RFC2616 . . . . . . . . . . . . . . . . . . . . . 191
G.2. Since draft-lafon-rfc2616bis-00 . . . . . . . . . . . . 192 G.2. Since draft-lafon-rfc2616bis-00 . . . . . . . . . . . . 191
G.3. Since draft-lafon-rfc2616bis-01 . . . . . . . . . . . . 191
Appendix H. Resolved issues (to be removed by RFC Editor Appendix H. Resolved issues (to be removed by RFC Editor
before publication) . . . . . . . . . . . . . . . . 193 before publication) . . . . . . . . . . . . . . . . 192
H.1. rfc2606-compliance . . . . . . . . . . . . . . . . . . . 193 H.1. rfc2606-compliance . . . . . . . . . . . . . . . . . . . 192
H.2. editor-notes . . . . . . . . . . . . . . . . . . . . . . 193 H.2. references_style . . . . . . . . . . . . . . . . . . . . 192
H.3. verscase . . . . . . . . . . . . . . . . . . . . . . . . 193 H.3. media-reg . . . . . . . . . . . . . . . . . . . . . . . 192
H.4. unsafe-uri . . . . . . . . . . . . . . . . . . . . . . . 193 H.4. location-fragments . . . . . . . . . . . . . . . . . . . 193
H.5. charactersets . . . . . . . . . . . . . . . . . . . . . 194
H.6. identity . . . . . . . . . . . . . . . . . . . . . . . . 194
H.7. chunk-size . . . . . . . . . . . . . . . . . . . . . . . 194
H.8. msg-len-chars . . . . . . . . . . . . . . . . . . . . . 195
H.9. uriquery . . . . . . . . . . . . . . . . . . . . . . . . 195
H.10. post . . . . . . . . . . . . . . . . . . . . . . . . . . 195
H.11. ifrange206 . . . . . . . . . . . . . . . . . . . . . . . 195
H.12. saferedirect . . . . . . . . . . . . . . . . . . . . . . 196
H.13. trailer-hop . . . . . . . . . . . . . . . . . . . . . . 196
H.14. invalidupd . . . . . . . . . . . . . . . . . . . . . . . 196
H.15. noclose1xx . . . . . . . . . . . . . . . . . . . . . . . 197
H.16. via-must . . . . . . . . . . . . . . . . . . . . . . . . 197
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) . . . . . . . . . . . . . . . . . . . . 198 publication) . . . . . . . . . . . . . . . . . . . . 194
I.1. rfc2616bis . . . . . . . . . . . . . . . . . . . . . . . 198 I.1. rfc2616bis . . . . . . . . . . . . . . . . . . . . . . . 194
I.2. unneeded_references . . . . . . . . . . . . . . . . . . 198 I.2. unneeded_references . . . . . . . . . . . . . . . . . . 194
I.3. edit . . . . . . . . . . . . . . . . . . . . . . . . . . 198 I.3. edit . . . . . . . . . . . . . . . . . . . . . . . . . . 194
I.4. media-reg . . . . . . . . . . . . . . . . . . . . . . . 198 I.4. rfc2048_informative_and_obsolete . . . . . . . . . . . . 194
I.5. languagetag . . . . . . . . . . . . . . . . . . . . . . 198 I.5. languagetag . . . . . . . . . . . . . . . . . . . . . . 194
I.6. location-fragments . . . . . . . . . . . . . . . . . . . 199 I.6. fragment-combination . . . . . . . . . . . . . . . . . . 195
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200 Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 196
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 211 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 207
Intellectual Property and Copyright Statements . . . . . . . . . 214 Intellectual Property and Copyright Statements . . . . . . . . . 210
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 19, line 4 skipping to change at page 18, 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:
1. If the response status code is 100 (Continue) or 101 (Switching 1. If the response status code is 100 (Continue) or 101 (Switching
Protocols), the response MAY include a Date header field, at the Protocols), the response MAY include a Date header field, at the
server's option. server's option.
2. If the response status code conveys a server error, e.g. 500 2. If the response status code conveys a server error, e.g. 500
(Internal Server Error) or 503 (Service Unavailable), and it is (Internal Server Error) or 503 (Service Unavailable), and it is
inconvenient or impossible to generate a valid Date. inconvenient or impossible to generate a valid Date.
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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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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
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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 149, line 42 skipping to change at page 148, 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 159, line 6 skipping to change at page 157, 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 161, line 12 skipping to change at page 159, 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 163, line 17 skipping to change at page 161, 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 167, line 33 skipping to change at page 165, 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:
skipping to change at page 170, line 10 skipping to change at page 168, line 10
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 171, line 7 skipping to change at page 169, 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
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.
[4] Berners-Lee, T., Masinter, L., and M. McCahill, "Uniform
Resource Locators (URL)", RFC 1738, December 1994.
[5] Berners-Lee, T. and D. Connolly, "Hypertext Markup Language -
2.0", RFC 1866, November 1995.
[6] Berners-Lee, T., Fielding, R., and H. Nielsen, "Hypertext
Transfer Protocol -- HTTP/1.0", RFC 1945, May 1996.
[7] Freed, N. and N. Borenstein, "Multipurpose Internet Mail
Extensions (MIME) Part One: Format of Internet Message Bodies",
RFC 2045, November 1996.
[8] Braden, R., "Requirements for Internet Hosts - Application and Part 1: Latin alphabet No. 1, ISO-8859-1:1987. Part 2:
Support", STD 3, RFC 1123, October 1989. Latin alphabet No. 2, ISO-8859-2, 1987. Part 3: Latin
alphabet No. 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.
[9] Crocker, D., "Standard for the format of ARPA Internet text [Luo1998] Luotonen, A., "Tunneling TCP based protocols through Web
messages", STD 11, RFC 822, August 1982. proxy servers", Work in Progress.
[10] Davis, F., Kahle, B., Morris, H., Salem, J., Shen, T., Wang, [Nie1997] Nielsen, H., Gettys, J., Prud'hommeaux, E., Lie, H., and
R., Sui, J., and M. Grinbaum, "WAIS Interface Protocol C. Lilley, "Network Performance Effects of HTTP/1.1, CSS1,
Prototype Functional Specification (v1.5)", Thinking Machines and PNG", Proceedings of ACM SIGCOMM '97, Cannes France ,
Corporation , April 1990. Sep 1997.
[11] Fielding, R., "Relative Uniform Resource Locators", RFC 1808, [Pad1995] Padmanabhan, V. and J. Mogul, "Improving HTTP Latency",
June 1995. Computer Networks and ISDN Systems v. 28, pp. 25-35,
Dec 1995.
[12] Horton, M. and R. Adams, "Standard for interchange of USENET Slightly revised version of paper in Proc. 2nd
messages", RFC 1036, December 1987. International WWW Conference '94: Mosaic and the Web, Oct.
1994, which is available at <http://www.ncsa.uiuc.edu/SDG/
IT94/Proceedings/DDay/mogul/HTTPLatency.html>.
[13] Kantor, B. and P. Lapsley, "Network News Transfer Protocol", [RFC1036] Horton, M. and R. Adams, "Standard for interchange of
RFC 977, February 1986. USENET messages", RFC 1036, December 1987.
[14] Moore, K., "MIME (Multipurpose Internet Mail Extensions) Part [RFC1123] Braden, R., "Requirements for Internet Hosts - Application
Three: Message Header Extensions for Non-ASCII Text", RFC 2047, and Support", STD 3, RFC 1123, October 1989.
November 1996.
[15] Masinter, L. and E. Nebel, "Form-based File Upload in HTML", [RFC1305] Mills, D., "Network Time Protocol (Version 3)
RFC 1867, November 1995. Specification, Implementation", RFC 1305, March 1992.
[16] Postel, J., "Simple Mail Transfer Protocol", STD 10, RFC 821, [RFC1436] Anklesaria, F., McCahill, M., Lindner, P., Johnson, D.,
August 1982. Torrey, D., and B. Alberti, "The Internet Gopher Protocol
(a distributed document search and retrieval protocol)",
RFC 1436, March 1993.
[17] Postel, J., "Media Type Registration Procedure", RFC 1590, [RFC1590] Postel, J., "Media Type Registration Procedure", RFC 1590,
March 1994. March 1994.
[18] Postel, J. and J. Reynolds, "File Transfer Protocol", STD 9, [RFC1630] Berners-Lee, T., "Universal Resource Identifiers in WWW: A
RFC 959, October 1985. 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.
[19] Reynolds, J. and J. Postel, "Assigned Numbers", STD 2, [RFC1700] Reynolds, J. and J. Postel, "Assigned Numbers", STD 2,
RFC 1700, October 1994. RFC 1700, October 1994.
[20] Masinter, L. and K. Sollins, "Functional Requirements for [RFC1737] Masinter, L. and K. Sollins, "Functional Requirements for
Uniform Resource Names", RFC 1737, December 1994. Uniform Resource Names", RFC 1737, December 1994.
[21] American National Standards Institute, "Coded Character Set -- [RFC1738] Berners-Lee, T., Masinter, L., and M. McCahill, "Uniform
7-bit American Standard Code for Information Interchange", Resource Locators (URL)", RFC 1738, December 1994.
ANSI X3.4, 1986.
[22] International Organization for Standardization, "Information [RFC1766] Alvestrand, H., "Tags for the Identification of
technology - 8-bit single byte coded graphic - character sets", Languages", RFC 1766, March 1995.
1987-1990.
Part 1: Latin alphabet No. 1, ISO-8859-1:1987. Part 2: Latin [RFC1806] Troost, R. and S. Dorner, "Communicating Presentation
alphabet No. 2, ISO-8859-2, 1987. Part 3: Latin alphabet No. Information in Internet Messages: The Content-Disposition
3, ISO-8859-3, 1988. Part 4: Latin alphabet No. 4, ISO-8859-4, Header", RFC 1806, June 1995.
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", [RFC1808] Fielding, R., "Relative Uniform Resource Locators",
RFC 1808, June 1995.
[RFC1864] Myers, J. and M. Rose, "The Content-MD5 Header Field",
RFC 1864, October 1995. RFC 1864, October 1995.
[24] Carpenter, B. and Y. Rekhter, "Renumbering Needs Work", [RFC1866] Berners-Lee, T. and D. Connolly, "Hypertext Markup
RFC 1900, February 1996. Language - 2.0", RFC 1866, November 1995.
[25] Deutsch, P., Gailly, J-L., Adler, M., Deutsch, L., and G. [RFC1867] Masinter, L. and E. Nebel, "Form-based File Upload in
HTML", RFC 1867, November 1995.
Randers-Pehrson, "GZIP file format specification version 4.3", [RFC1900] Carpenter, B. and Y. Rekhter, "Renumbering Needs Work",
RFC 1952, May 1996. RFC 1900, February 1996.
[26] Padmanabhan, V. and J. Mogul, "Improving HTTP Latency", [RFC1945] Berners-Lee, T., Fielding, R., and H. Nielsen, "Hypertext
Computer Networks and ISDN Systems v. 28, pp. 25-35, Dec 1995. Transfer Protocol -- HTTP/1.0", RFC 1945, May 1996.
Slightly revised version of paper in Proc. 2nd International [RFC1950] Deutsch, L. and J-L. Gailly, "ZLIB Compressed Data Format
WWW Conference '94: Mosaic and the Web, Oct. 1994, which is Specification version 3.3", RFC 1950, May 1996.
available at <http://www.ncsa.uiuc.edu/SDG/IT94/Proceedings/
DDay/mogul/HTTPLatency.html>.
[27] Touch, J., Heidemann, J., and K. Obraczka, "Analysis of HTTP [RFC1951] Deutsch, P., "DEFLATE Compressed Data Format Specification
Performance", ISI Research Report ISI/RR-98-463 (original version 1.3", RFC 1951, May 1996.
report dated Aug.1996), Aug 1998,
<http://www.isi.edu/touch/pubs/http-perf96/>.
[28] Mills, D., "Network Time Protocol (Version 3) Specification, [RFC1952] Deutsch, P., Gailly, J-L., Adler, M., Deutsch, L., and G.
Implementation", RFC 1305, March 1992. Randers-Pehrson, "GZIP file format specification version
4.3", RFC 1952, May 1996.
[29] Deutsch, P., "DEFLATE Compressed Data Format Specification [RFC2026] Bradner, S., "The Internet Standards Process -- Revision
version 1.3", RFC 1951, May 1996. 3", BCP 9, RFC 2026, October 1996.
[30] Spero, S., "Analysis of HTTP Performance Problems", [RFC2045] Freed, N. and N. Borenstein, "Multipurpose Internet Mail
<http://sunsite.unc.edu/mdma-release/http-prob.html>. Extensions (MIME) Part One: Format of Internet Message
Bodies", RFC 2045, November 1996.
[31] Deutsch, L. and J-L. Gailly, "ZLIB Compressed Data Format [RFC2046] Freed, N. and N. Borenstein, "Multipurpose Internet Mail
Specification version 3.3", RFC 1950, May 1996. Extensions (MIME) Part Two: Media Types", RFC 2046,
November 1996.
[32] Franks, J., Hallam-Baker, P., Hostetler, J., Leach, P., [RFC2047] Moore, K., "MIME (Multipurpose Internet Mail Extensions)
Luotonen, A., Sink, E., and L. Stewart, "An Extension to HTTP : Part Three: Message Header Extensions for Non-ASCII Text",
Digest Access Authentication", RFC 2069, January 1997. RFC 2047, November 1996.
[33] Fielding, R., Gettys, J., Mogul, J., Nielsen, H., and T. [RFC2049] Freed, N. and N. Borenstein, "Multipurpose Internet Mail
Extensions (MIME) Part Five: Conformance Criteria and
Examples", RFC 2049, November 1996.
[RFC2068] Fielding, R., Gettys, J., Mogul, J., Nielsen, H., and T.
Berners-Lee, "Hypertext Transfer Protocol -- HTTP/1.1", Berners-Lee, "Hypertext Transfer Protocol -- HTTP/1.1",
RFC 2068, January 1997. RFC 2068, January 1997.
[34] Bradner, S., "Key words for use in RFCs to Indicate Requirement [RFC2069] Franks, J., Hallam-Baker, P., Hostetler, J., Leach, P.,
Levels", BCP 14, RFC 2119, March 1997. Luotonen, A., Sink, E., and L. Stewart, "An Extension to
HTTP : Digest Access Authentication", RFC 2069,
January 1997.
[35] Troost, R. and S. Dorner, "Communicating Presentation [RFC2076] Palme, J., "Common Internet Message Headers", RFC 2076,
Information in Internet Messages: The Content-Disposition February 1997.
Header", RFC 1806, June 1995.
[36] Mogul, J., Fielding, R., Gettys, J., and H. Nielsen, "Use and [RFC2110] Palme, J. and A. Hopmann, "MIME E-mail Encapsulation of
Interpretation of HTTP Version Numbers", RFC 2145, May 1997. Aggregate Documents, such as HTML (MHTML)", RFC 2110,
March 1997.
[37] Palme, J., "Common Internet Message Headers", RFC 2076, [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
February 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[38] Yergeau, F., "UTF-8, a transformation format of ISO 10646", [RFC2145] Mogul, J., Fielding, R., Gettys, J., and H. Nielsen, "Use
RFC 2279, January 1998. and Interpretation of HTTP Version Numbers", RFC 2145,
May 1997.
[39] Nielsen, H., Gettys, J., Prud'hommeaux, E., Lie, H., and C. [RFC2183] Troost, R., Dorner, S., and K. Moore, "Communicating
Lilley, "Network Performance Effects of HTTP/1.1, CSS1, and Presentation Information in Internet Messages: The
PNG", Proceedings of ACM SIGCOMM '97, Cannes France , Sep 1997. Content-Disposition Header Field", RFC 2183, August 1997.
[40] Freed, N. and N. Borenstein, "Multipurpose Internet Mail [RFC2277] Alvestrand, H., "IETF Policy on Character Sets and
Extensions (MIME) Part Two: Media Types", RFC 2046, Languages", BCP 18, RFC 2277, January 1998.
November 1996.
[41] Alvestrand, H., "IETF Policy on Character Sets and Languages", [RFC2279] Yergeau, F., "UTF-8, a transformation format of ISO
BCP 18, RFC 2277, January 1998. 10646", RFC 2279, January 1998.
[42] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform [RFC2324] Masinter, L., "Hyper Text Coffee Pot Control Protocol
(HTCPCP/1.0)", RFC 2324, April 1998.
[RFC2396] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifiers (URI): Generic Syntax", RFC 2396, Resource Identifiers (URI): Generic Syntax", RFC 2396,
August 1998. August 1998.
[43] Franks, J., Hallam-Baker, P., Hostetler, J., Lawrence, S., [RFC2617] Franks, J., Hallam-Baker, P., Hostetler, J., Lawrence, S.,
Leach, P., Luotonen, A., and L. Stewart, "HTTP Authentication: Leach, P., Luotonen, A., and L. Stewart, "HTTP
Basic and Digest Access Authentication", RFC 2617, June 1999. Authentication: Basic and Digest Access Authentication",
RFC 2617, June 1999.
[44] Luotonen, A., "Tunneling TCP based protocols through Web proxy [RFC821] Postel, J., "Simple Mail Transfer Protocol", STD 10,
servers", Work in Progress. RFC 821, August 1982.
[45] Palme, J. and A. Hopmann, "MIME E-mail Encapsulation of [RFC822] Crocker, D., "Standard for the format of ARPA Internet
Aggregate Documents, such as HTML (MHTML)", RFC 2110, text messages", STD 11, RFC 822, August 1982.
March 1997.
[46] Bradner, S., "The Internet Standards Process -- Revision 3", [RFC959] Postel, J. and J. Reynolds, "File Transfer Protocol",
BCP 9, RFC 2026, October 1996. STD 9, RFC 959, October 1985.
[47] Masinter, L., "Hyper Text Coffee Pot Control Protocol [RFC977] Kantor, B. and P. Lapsley, "Network News Transfer
(HTCPCP/1.0)", RFC 2324, April 1998. Protocol", RFC 977, February 1986.
[48] Freed, N. and N. Borenstein, "Multipurpose Internet Mail [Spero] Spero, S., "Analysis of HTTP Performance Problems",
Extensions (MIME) Part Five: Conformance Criteria and <http://sunsite.unc.edu/mdma-release/http-prob.html>.
Examples", RFC 2049, November 1996.
[49] Troost, R., Dorner, S., and K. Moore, "Communicating [Tou1998] Touch, J., Heidemann, J., and K. Obraczka, "Analysis of
Presentation Information in Internet Messages: The Content- HTTP Performance", ISI Research Report ISI/RR-98-463
Disposition Header Field", RFC 2183, August 1997. (original report dated Aug.1996), Aug 1998,
<http://www.isi.edu/touch/pubs/http-perf96/>.
[USASCII] American National Standards Institute, "Coded Character
Set -- 7-bit American Standard Code for Information
Interchange", ANSI X3.4, 1986.
[WAIS] Davis, F., Kahle, B., Morris, H., Salem, J., Shen, T.,
Wang, R., Sui, J., and M. Grinbaum, "WAIS Interface
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 180, line 8 skipping to change at page 179, 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.