HTTP/1.1, part 2: Message Semantics
draft-ietf-httpbis-p2-semantics-19
The information below is for an old version of the document.
| Document | Type |
This is an older version of an Internet-Draft that was ultimately published as RFC 7231.
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| Authors | Roy T. Fielding , Yves Lafon , Julian Reschke | ||
| Last updated | 2012-07-05 (Latest revision 2012-03-12) | ||
| RFC stream | Internet Engineering Task Force (IETF) | ||
| Formats | |||
| Reviews | |||
| Additional resources | Mailing list discussion | ||
| Stream | WG state | WG Document | |
| Document shepherd | (None) | ||
| IESG | IESG state | Became RFC 7231 (Proposed Standard) | |
| Consensus boilerplate | Unknown | ||
| Telechat date | (None) | ||
| Responsible AD | Barry Leiba | ||
| Send notices to | httpbis-chairs@tools.ietf.org, draft-ietf-httpbis-p2-semantics@tools.ietf.org |
draft-ietf-httpbis-p2-semantics-19
Internet-Draft HTTP/1.1, Part 2 March 2012 a fixed limitation. 7.3.1. 300 Multiple Choices The target resource has more than one representation, each with its own specific location, and agent-driven negotiation information (Section 5 of [Part3]) is being provided so that the user (or user agent) can select a preferred representation by redirecting its request to that location. Unless it was a HEAD request, the response SHOULD include a representation containing a list of representation metadata and location(s) from which the user or user agent can choose the one most appropriate. Depending upon the format and the capabilities of the user agent, selection of the most appropriate choice MAY be performed automatically. However, this specification does not define any standard for such automatic selection. If the server has a preferred choice of representation, it SHOULD include the specific URI for that representation in the Location field; user agents MAY use the Location field value for automatic redirection. Caches MAY use a heuristic (see Section 2.3.1.1 of [Part6]) to determine freshness for 300 responses. 7.3.2. 301 Moved Permanently The target resource has been assigned a new permanent URI and any future references to this resource SHOULD use one of the returned URIs. Clients with link editing capabilities ought to automatically re-link references to the effective request URI to one or more of the new references returned by the server, where possible. Caches MAY use a heuristic (see Section 2.3.1.1 of [Part6]) to determine freshness for 301 responses. The new permanent URI SHOULD be given by the Location field in the response. A response payload can contain a short hypertext note with a hyperlink to the new URI(s). Note: For historic reasons, user agents MAY change the request method from POST to GET for the subsequent request. If this behavior is undesired, status code 307 (Temporary Redirect) can be used instead. Fielding, et al. Expires September 13, 2012 [Page 31] Internet-Draft HTTP/1.1, Part 2 March 2012 7.3.3. 302 Found The target resource resides temporarily under a different URI. Since the redirection might be altered on occasion, the client SHOULD continue to use the effective request URI for future requests. The temporary URI SHOULD be given by the Location field in the response. A response payload can contain a short hypertext note with a hyperlink to the new URI(s). Note: For historic reasons, user agents MAY change the request method from POST to GET for the subsequent request. If this behavior is undesired, status code 307 (Temporary Redirect) can be used instead. 7.3.4. 303 See Other The 303 status code indicates that the server is redirecting the user agent to a different resource, as indicated by a URI in the Location header field, that is intended to provide an indirect response to the original request. In order to satisfy the original request, a user agent SHOULD perform a retrieval request using the Location URI (a GET or HEAD request if using HTTP), which may itself be redirected further, and present the eventual result as an answer to the original request. Note that the new URI in the Location header field is not considered equivalent to the effective request URI. This status code is generally applicable to any HTTP method. It is primarily used to allow the output of a POST action to redirect the user agent to a selected resource, since doing so provides the information corresponding to the POST response in a form that can be separately identified, bookmarked, and cached independent of the original request. A 303 response to a GET request indicates that the requested resource does not have a representation of its own that can be transferred by the server over HTTP. The Location URI indicates a resource that is descriptive of the target resource, such that the follow-on representation might be useful to recipients without implying that it adequately represents the target resource. Note that answers to the questions of what can be represented, what representations are adequate, and what might be a useful description are outside the scope of HTTP and thus entirely determined by the URI owner(s). Except for responses to a HEAD request, the representation of a 303 response SHOULD contain a short hypertext note with a hyperlink to the Location URI. Fielding, et al. Expires September 13, 2012 [Page 32] Internet-Draft HTTP/1.1, Part 2 March 2012 7.3.5. 305 Use Proxy The 305 status code was defined in a previous version of this specification (see Appendix A), and is now deprecated. 7.3.6. 306 (Unused) The 306 status code was used in a previous version of the specification, is no longer used, and the code is reserved. 7.3.7. 307 Temporary Redirect The target resource resides temporarily under a different URI. Since the redirection can change over time, the client SHOULD continue to use the effective request URI for future requests. The temporary URI SHOULD be given by the Location field in the response. A response payload can contain a short hypertext note with a hyperlink to the new URI(s). Note: This status code is similar to 302 Found, except that it does not allow rewriting the request method from POST to GET. This specification defines no equivalent counterpart for 301 Moved Permanently. 7.4. Client Error 4xx The 4xx class of status code is intended for cases in which the client seems to have erred. Except when responding to a HEAD request, the server SHOULD include a representation containing an explanation of the error situation, and whether it is a temporary or permanent condition. These status codes are applicable to any request method. User agents SHOULD display any included representation to the user. 7.4.1. 400 Bad Request The server cannot or will not process the request, due to a client error (e.g., malformed syntax). 7.4.2. 402 Payment Required This code is reserved for future use. 7.4.3. 403 Forbidden The server understood the request, but refuses to authorize it. Providing different user authentication credentials might be Fielding, et al. Expires September 13, 2012 [Page 33] Internet-Draft HTTP/1.1, Part 2 March 2012 successful, but any credentials that were provided in the request are insufficient. The request SHOULD NOT be repeated with the same credentials. If the request method was not HEAD and the server wishes to make public why the request has not been fulfilled, it SHOULD describe the reason for the refusal in the representation. If the server does not wish to make this information available to the client, the status code 404 (Not Found) MAY be used instead. 7.4.4. 404 Not Found The server has not found anything matching the effective request URI. No indication is given of whether the condition is temporary or permanent. The 410 (Gone) status code SHOULD be used if the server knows, through some internally configurable mechanism, that an old resource is permanently unavailable and has no forwarding address. This status code is commonly used when the server does not wish to reveal exactly why the request has been refused, or when no other response is applicable. 7.4.5. 405 Method Not Allowed The method specified in the request-line is not allowed for the target resource. The response MUST include an Allow header field containing a list of valid methods for the requested resource. 7.4.6. 406 Not Acceptable The resource identified by the request is only capable of generating response representations which have content characteristics not acceptable according to the Accept and Accept-* header fields sent in the request (see Section 6 of [Part3]). Unless it was a HEAD request, the response SHOULD include a representation containing a list of available representation characteristics and location(s) from which the user or user agent can choose the one most appropriate. Depending upon the format and the capabilities of the user agent, selection of the most appropriate choice MAY be performed automatically. However, this specification does not define any standard for such automatic selection. Note: HTTP/1.1 servers are allowed to return responses which are not acceptable according to the accept header fields sent in the request. In some cases, this might even be preferable to sending a 406 response. User agents are encouraged to inspect the header fields of an incoming response to determine if it is acceptable. Fielding, et al. Expires September 13, 2012 [Page 34] Internet-Draft HTTP/1.1, Part 2 March 2012 If the response could be unacceptable, a user agent SHOULD temporarily stop receipt of more data and query the user for a decision on further actions. 7.4.7. 408 Request Timeout The client did not produce a request within the time that the server was prepared to wait. The client MAY repeat the request without modifications at any later time. 7.4.8. 409 Conflict The request could not be completed due to a conflict with the current state of the resource. This code is only allowed in situations where it is expected that the user might be able to resolve the conflict and resubmit the request. The response body SHOULD include enough information for the user to recognize the source of the conflict. Ideally, the response representation would include enough information for the user or user agent to fix the problem; however, that might not be possible and is not required. Conflicts are most likely to occur in response to a PUT request. For example, if versioning were being used and the representation being PUT included changes to a resource which conflict with those made by an earlier (third-party) request, the server might use the 409 response to indicate that it can't complete the request. In this case, the response representation would likely contain a list of the differences between the two versions. 7.4.9. 410 Gone The target resource is no longer available at the server and no forwarding address is known. This condition is expected to be considered permanent. Clients with link editing capabilities SHOULD delete references to the effective request URI after user approval. If the server does not know, or has no facility to determine, whether or not the condition is permanent, the status code 404 (Not Found) SHOULD be used instead. The 410 response is primarily intended to assist the task of web maintenance by notifying the recipient that the resource is intentionally unavailable and that the server owners desire that remote links to that resource be removed. Such an event is common for limited-time, promotional services and for resources belonging to individuals no longer working at the server's site. It is not necessary to mark all permanently unavailable resources as "gone" or to keep the mark for any length of time -- that is left to the discretion of the server owner. Fielding, et al. Expires September 13, 2012 [Page 35] Internet-Draft HTTP/1.1, Part 2 March 2012 Caches MAY use a heuristic (see Section 2.3.1.1 of [Part6]) to determine freshness for 410 responses. 7.4.10. 411 Length Required The server refuses to accept the request without a defined Content- Length. The client MAY repeat the request if it adds a valid Content-Length header field containing the length of the message body in the request message. 7.4.11. 413 Request Representation Too Large The server is refusing to process a request because the request representation is larger than the server is willing or able to process. The server MAY close the connection to prevent the client from continuing the request. If the condition is temporary, the server SHOULD include a Retry- After header field to indicate that it is temporary and after what time the client MAY try again. 7.4.12. 414 URI Too Long The server is refusing to service the request because the effective request URI is longer than the server is willing to interpret. This rare condition is only likely to occur when a client has improperly converted a POST request to a GET request with long query information, when the client has descended into a URI "black hole" of redirection (e.g., a redirected URI prefix that points to a suffix of itself), or when the server is under attack by a client attempting to exploit security holes present in some servers using fixed-length buffers for reading or manipulating the request-target. 7.4.13. 415 Unsupported Media Type The server is refusing to service the request because the request payload is in a format not supported by this request method on the target resource. 7.4.14. 417 Expectation Failed The expectation given in an Expect header field (see Section 10.3) could not be met by this server, or, if the server is a proxy, the server has unambiguous evidence that the request could not be met by the next-hop server. Fielding, et al. Expires September 13, 2012 [Page 36] Internet-Draft HTTP/1.1, Part 2 March 2012 7.4.15. 426 Upgrade Required The request can not be completed without a prior protocol upgrade. This response MUST include an Upgrade header field (Section 6.5 of [Part1]) specifying the required protocols. Example: HTTP/1.1 426 Upgrade Required Upgrade: HTTP/3.0 Connection: Upgrade Content-Length: 53 Content-Type: text/plain This service requires use of the HTTP/3.0 protocol. The server SHOULD include a message body in the 426 response which indicates in human readable form the reason for the error and describes any alternative courses which may be available to the user. 7.5. Server Error 5xx Response status codes beginning with the digit "5" indicate cases in which the server is aware that it has erred or is incapable of performing the request. Except when responding to a HEAD request, the server SHOULD include a representation containing an explanation of the error situation, and whether it is a temporary or permanent condition. User agents SHOULD display any included representation to the user. These response codes are applicable to any request method. 7.5.1. 500 Internal Server Error The server encountered an unexpected condition which prevented it from fulfilling the request. 7.5.2. 501 Not Implemented The server does not support the functionality required to fulfill the request. This is the appropriate response when the server does not recognize the request method and is not capable of supporting it for any resource. 7.5.3. 502 Bad Gateway The server, while acting as a gateway or proxy, received an invalid response from the upstream server it accessed in attempting to fulfill the request. Fielding, et al. Expires September 13, 2012 [Page 37] Internet-Draft HTTP/1.1, Part 2 March 2012 7.5.4. 503 Service Unavailable The server is currently unable to handle the request due to a temporary overloading or maintenance of the server. The implication is that this is a temporary condition which will be alleviated after some delay. If known, the length of the delay MAY be indicated in a Retry-After header field (Section 10.8). If no Retry-After is given, the client SHOULD handle the response as it would for a 500 response. Note: The existence of the 503 status code does not imply that a server must use it when becoming overloaded. Some servers might wish to simply refuse the connection. 7.5.5. 504 Gateway Timeout The server, while acting as a gateway or proxy, did not receive a timely response from the upstream server specified by the URI (e.g., HTTP, FTP, LDAP) or some other auxiliary server (e.g., DNS) it needed to access in attempting to complete the request. Note to implementors: some deployed proxies are known to return 400 or 500 when DNS lookups time out. 7.5.6. 505 HTTP Version Not Supported The server does not support, or refuses to support, the protocol version that was used in the request message. The server is indicating that it is unable or unwilling to complete the request using the same major version as the client, as described in Section 2.6 of [Part1], other than with this error message. The response SHOULD contain a representation describing why that version is not supported and what other protocols are supported by that server. 8. Date/Time Formats HTTP applications have historically allowed three different formats for date/time stamps. However, the preferred format is a fixed- length subset of that defined by [RFC1123]: Sun, 06 Nov 1994 08:49:37 GMT ; RFC 1123 The other formats are described here only for compatibility with obsolete implementations. Sunday, 06-Nov-94 08:49:37 GMT ; obsolete RFC 850 format Sun Nov 6 08:49:37 1994 ; ANSI C's asctime() format Fielding, et al. Expires September 13, 2012 [Page 38] Internet-Draft HTTP/1.1, Part 2 March 2012 HTTP/1.1 clients and servers that parse a date value MUST accept all three formats (for compatibility with HTTP/1.0), though they MUST only generate the RFC 1123 format for representing HTTP-date values in header fields. All HTTP date/time stamps MUST be represented in Greenwich Mean Time (GMT), without exception. For the purposes of HTTP, GMT is exactly equal to UTC (Coordinated Universal Time). This is indicated in the first two formats by the inclusion of "GMT" as the three-letter abbreviation for time zone, and MUST be assumed when reading the asctime format. HTTP-date is case sensitive and MUST NOT include additional whitespace beyond that specifically included as SP in the grammar. HTTP-date = rfc1123-date / obs-date Preferred format: Fielding, et al. Expires September 13, 2012 [Page 39] Internet-Draft HTTP/1.1, Part 2 March 2012 rfc1123-date = day-name "," SP date1 SP time-of-day SP GMT ; fixed length subset of the format defined in ; Section 5.2.14 of [RFC1123] day-name = %x4D.6F.6E ; "Mon", case-sensitive / %x54.75.65 ; "Tue", case-sensitive / %x57.65.64 ; "Wed", case-sensitive / %x54.68.75 ; "Thu", case-sensitive / %x46.72.69 ; "Fri", case-sensitive / %x53.61.74 ; "Sat", case-sensitive / %x53.75.6E ; "Sun", case-sensitive date1 = day SP month SP year ; e.g., 02 Jun 1982 day = 2DIGIT month = %x4A.61.6E ; "Jan", case-sensitive / %x46.65.62 ; "Feb", case-sensitive / %x4D.61.72 ; "Mar", case-sensitive / %x41.70.72 ; "Apr", case-sensitive / %x4D.61.79 ; "May", case-sensitive / %x4A.75.6E ; "Jun", case-sensitive / %x4A.75.6C ; "Jul", case-sensitive / %x41.75.67 ; "Aug", case-sensitive / %x53.65.70 ; "Sep", case-sensitive / %x4F.63.74 ; "Oct", case-sensitive / %x4E.6F.76 ; "Nov", case-sensitive / %x44.65.63 ; "Dec", case-sensitive year = 4DIGIT GMT = %x47.4D.54 ; "GMT", case-sensitive time-of-day = hour ":" minute ":" second ; 00:00:00 - 23:59:59 hour = 2DIGIT minute = 2DIGIT second = 2DIGIT The semantics of day-name, day, month, year, and time-of-day are the same as those defined for the RFC 5322 constructs with the corresponding name ([RFC5322], Section 3.3). Obsolete formats: obs-date = rfc850-date / asctime-date Fielding, et al. Expires September 13, 2012 [Page 40] Internet-Draft HTTP/1.1, Part 2 March 2012 rfc850-date = day-name-l "," SP date2 SP time-of-day SP GMT date2 = day "-" month "-" 2DIGIT ; day-month-year (e.g., 02-Jun-82) day-name-l = %x4D.6F.6E.64.61.79 ; "Monday", case-sensitive / %x54.75.65.73.64.61.79 ; "Tuesday", case-sensitive / %x57.65.64.6E.65.73.64.61.79 ; "Wednesday", case-sensitive / %x54.68.75.72.73.64.61.79 ; "Thursday", case-sensitive / %x46.72.69.64.61.79 ; "Friday", case-sensitive / %x53.61.74.75.72.64.61.79 ; "Saturday", case-sensitive / %x53.75.6E.64.61.79 ; "Sunday", case-sensitive asctime-date = day-name SP date3 SP time-of-day SP year date3 = month SP ( 2DIGIT / ( SP 1DIGIT )) ; month day (e.g., Jun 2) Note: Recipients of date values are encouraged to be robust in accepting date values that might have been sent by non-HTTP applications, as is sometimes the case when retrieving or posting messages via proxies/gateways to SMTP or NNTP. Note: HTTP requirements for the date/time stamp format apply only to their usage within the protocol stream. Clients and servers are not required to use these formats for user presentation, request logging, etc. 9. Product Tokens Product tokens are used to allow communicating applications to identify themselves by software name and version. Most fields using product tokens also allow sub-products which form a significant part of the application to be listed, separated by whitespace. By convention, the products are listed in order of their significance for identifying the application. product = token ["/" product-version] product-version = token Examples: User-Agent: CERN-LineMode/2.15 libwww/2.17b3 Server: Apache/0.8.4 Product tokens SHOULD be short and to the point. They MUST NOT be used for advertising or other non-essential information. Although any token octet MAY appear in a product-version, this token SHOULD only be used for a version identifier (i.e., successive versions of Fielding, et al. Expires September 13, 2012 [Page 41] Internet-Draft HTTP/1.1, Part 2 March 2012 the same product SHOULD only differ in the product-version portion of the product value). 10. Header Field Definitions This section defines the syntax and semantics of HTTP/1.1 header fields related to request and response semantics. 10.1. Allow The "Allow" header field lists the set of methods advertised as supported by the target resource. The purpose of this field is strictly to inform the recipient of valid request methods associated with the resource. Allow = #method Example of use: Allow: GET, HEAD, PUT The actual set of allowed methods is defined by the origin server at the time of each request. A proxy MUST NOT modify the Allow header field -- it does not need to understand all the methods specified in order to handle them according to the generic message handling rules. 10.2. Date The "Date" header field represents the date and time at which the message was originated, having the same semantics as the Origination Date Field (orig-date) defined in Section 3.6.1 of [RFC5322]. The field value is an HTTP-date, as defined in Section 8; it MUST be sent in rfc1123-date format. Date = HTTP-date An example is Date: Tue, 15 Nov 1994 08:12:31 GMT Origin servers MUST include a Date header field in all responses, except in these cases: 1. If the response status code is 100 (Continue) or 101 (Switching Protocols), the response MAY include a Date header field, at the server's option. Fielding, et al. Expires September 13, 2012 [Page 42] Internet-Draft HTTP/1.1, Part 2 March 2012 2. If the response status code conveys a server error, e.g., 500 (Internal Server Error) or 503 (Service Unavailable), and it is inconvenient or impossible to generate a valid Date. 3. If the server does not have a clock that can provide a reasonable approximation of the current time, its responses MUST NOT include a Date header field. 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 recipient. Clients can use the Date header field as well; in order to keep request messages small, they are advised not to include it when it doesn't convey any useful information (as is usually the case for requests that do not contain a payload). The HTTP-date sent in a Date header field SHOULD NOT represent a date and time subsequent to the generation of the message. It SHOULD represent the best available approximation of the date and time of message generation, unless the implementation has no means of generating a reasonably accurate date and time. In theory, the date ought to represent the moment just before the payload is generated. In practice, the date can be generated at any time during the message origination without affecting its semantic value. 10.3. Expect The "Expect" header field is used to indicate that particular server behaviors are required by the client. Expect = 1#expectation expectation = expect-name [ BWS "=" BWS expect-value ] *( OWS ";" [ OWS expect-param ] ) expect-param = expect-name [ BWS "=" BWS expect-value ] expect-name = token expect-value = token / quoted-string If all received Expect header field(s) are syntactically valid but contain an expectation that the recipient does not understand or cannot comply with, the recipient MUST respond with a 417 (Expectation Failed) status code. A recipient of a syntactically invalid Expectation header field MUST respond with a 4xx status code other than 417. The only expectation defined by this specification is: Fielding, et al. Expires September 13, 2012 [Page 43] Internet-Draft HTTP/1.1, Part 2 March 2012 100-continue The "100-continue" expectation is defined Section 6.4.3 of [Part1]. It does not support any expect-params. Comparison is case-insensitive for names (expect-name), and case- sensitive for values (expect-value). The Expect mechanism is hop-by-hop: the above requirements apply to any server, including proxies. However, the Expect header field itself is end-to-end; it MUST be forwarded if the request is forwarded. Many older HTTP/1.0 and HTTP/1.1 applications do not understand the Expect header field. 10.4. From The "From" header field, if given, SHOULD contain an Internet e-mail address for the human user who controls the requesting user agent. The address SHOULD be machine-usable, as defined by "mailbox" in Section 3.4 of [RFC5322]: From = mailbox mailbox = <mailbox, defined in [RFC5322], Section 3.4> An example is: From: webmaster@example.org This header field MAY be used for logging purposes and as a means for identifying the source of invalid or unwanted requests. It SHOULD NOT be used as an insecure form of access protection. The interpretation of this field is that the request is being performed on behalf of the person given, who accepts responsibility for the method performed. In particular, robot agents SHOULD include this header field so that the person responsible for running the robot can be contacted if problems occur on the receiving end. The Internet e-mail address in this field MAY be separate from the Internet host which issued the request. For example, when a request is passed through a proxy the original issuer's address SHOULD be used. The client SHOULD NOT send the From header field without the user's approval, as it might conflict with the user's privacy interests or their site's security policy. It is strongly recommended that the Fielding, et al. Expires September 13, 2012 [Page 44] Internet-Draft HTTP/1.1, Part 2 March 2012 user be able to disable, enable, and modify the value of this field at any time prior to a request. 10.5. Location The "Location" header field MAY be sent in responses to refer to a specific resource in accordance with the semantics of the status code. Location = URI-reference For 201 (Created) responses, the Location is the URI of the new resource which was created by the request. For 3xx responses, the location SHOULD indicate the server's preferred URI for automatic redirection to the resource. The field value consists of a single URI-reference. When it has the form of a relative reference ([RFC3986], Section 4.2), the final value is computed by resolving it against the effective request URI ([RFC3986], Section 5). If the original URI, as navigated to by the user agent, did contain a fragment identifier, and the final value does not, then the original URI's fragment identifier is added to the final value. For example, the original URI "http://www.example.org/~tim", combined with a field value given as: Location: /pub/WWW/People.html#tim would result in a final value of "http://www.example.org/pub/WWW/People.html#tim" An original URI "http://www.example.org/index.html#larry", combined with a field value given as: Location: http://www.example.net/index.html would result in a final value of "http://www.example.net/index.html#larry", preserving the original fragment identifier. Note: Some recipients attempt to recover from Location fields that are not valid URI references. This specification does not mandate or define such processing, but does allow it (see Section 1.1). There are circumstances in which a fragment identifier in a Location URI would not be appropriate. For instance, when it appears in a 201 Created response, where the Location header field specifies the URI Fielding, et al. Expires September 13, 2012 [Page 45] Internet-Draft HTTP/1.1, Part 2 March 2012 for the entire created resource. Note: The Content-Location header field (Section 6.7 of [Part3]) differs from Location in that the Content-Location identifies the most specific resource corresponding to the enclosed representation. It is therefore possible for a response to contain header fields for both Location and Content-Location. 10.6. Max-Forwards The "Max-Forwards" header field provides a mechanism with the TRACE (Section 6.8) and OPTIONS (Section 6.2) methods to limit the number of times that the request is forwarded by proxies. This can be useful when the client is attempting to trace a request which appears to be failing or looping mid-chain. Max-Forwards = 1*DIGIT The Max-Forwards value is a decimal integer indicating the remaining number of times this request message can be forwarded. Each recipient of a TRACE or OPTIONS request containing a Max- Forwards header field MUST check and update its value prior to forwarding the request. If the received value is zero (0), the recipient MUST NOT forward the request; instead, it MUST respond as the final recipient. If the received Max-Forwards value is greater than zero, then the forwarded message MUST contain an updated Max- Forwards field with a value decremented by one (1). The Max-Forwards header field MAY be ignored for all other request methods. 10.7. Referer The "Referer" [sic] header field allows the client to specify the URI of the resource from which the target URI was obtained (the "referrer", although the header field is misspelled.). The Referer header field allows servers to generate lists of back- links to resources for interest, logging, optimized caching, etc. It also allows obsolete or mistyped links to be traced for maintenance. Some servers use Referer as a means of controlling where they allow links from (so-called "deep linking"), but legitimate requests do not always contain a Referer header field. If the target URI was obtained from a source that does not have its own URI (e.g., input from the user keyboard), the Referer field MUST either be sent with the value "about:blank", or not be sent at all. Fielding, et al. Expires September 13, 2012 [Page 46] Internet-Draft HTTP/1.1, Part 2 March 2012 Note that this requirement does not apply to sources with non-HTTP URIs (e.g., FTP). Referer = absolute-URI / partial-URI Example: Referer: http://www.example.org/hypertext/Overview.html If the field value is a relative URI, it SHOULD be interpreted relative to the effective request URI. The URI MUST NOT include a fragment. See Section 12.2 for security considerations. 10.8. Retry-After The header "Retry-After" field can be used with a 503 (Service Unavailable) response to indicate how long the service is expected to be unavailable to the requesting client. This field MAY also be used with any 3xx (Redirection) response to indicate the minimum time the user-agent is asked to wait before issuing the redirected request. The value of this field can be either an HTTP-date or an integer number of seconds (in decimal) after the time of the response. Retry-After = HTTP-date / delta-seconds Time spans are non-negative decimal integers, representing time in seconds. delta-seconds = 1*DIGIT Two examples of its use are Retry-After: Fri, 31 Dec 1999 23:59:59 GMT Retry-After: 120 In the latter example, the delay is 2 minutes. 10.9. Server The "Server" header field contains information about the software used by the origin server to handle the request. The field can contain multiple product tokens (Section 9) and comments (Section 3.2 of [Part1]) identifying the server and any significant subproducts. The product tokens are listed in order of their significance for identifying the application. Fielding, et al. Expires September 13, 2012 [Page 47] Internet-Draft HTTP/1.1, Part 2 March 2012 Server = product *( RWS ( product / comment ) ) Example: Server: CERN/3.0 libwww/2.17 If the response is being forwarded through a proxy, the proxy application MUST NOT modify the Server header field. Instead, it MUST include a Via field (as described in Section 6.2 of [Part1]). Note: Revealing the specific software version of the server might allow the server machine to become more vulnerable to attacks against software that is known to contain security holes. Server implementors are encouraged to make this field a configurable option. 10.10. User-Agent The "User-Agent" header field contains information about the user agent originating the request. User agents SHOULD include this field with requests. Typically, it is used for statistical purposes, the tracing of protocol violations, and tailoring responses to avoid particular user agent limitations. The field can contain multiple product tokens (Section 9) and comments (Section 3.2 of [Part1]) identifying the agent and its significant subproducts. By convention, the product tokens are listed in order of their significance for identifying the application. Because this field is usually sent on every request a user agent makes, implementations are encouraged not to include needlessly fine- grained detail, and to limit (or even prohibit) the addition of subproducts by third parties. Overly long and detailed User-Agent field values make requests larger and can also be used to identify ("fingerprint") the user against their wishes. Likewise, implementations are encouraged not to use the product tokens of other implementations in order to declare compatibility with them, as this circumvents the purpose of the field. Finally, they are encouraged not to use comments to identify products; doing so makes the field value more difficult to parse. User-Agent = product *( RWS ( product / comment ) ) Example: Fielding, et al. Expires September 13, 2012 [Page 48] Internet-Draft HTTP/1.1, Part 2 March 2012 User-Agent: CERN-LineMode/2.15 libwww/2.17b3 11. IANA Considerations 11.1. Method Registry The registration procedure for HTTP request methods is defined by Section 2.2 of this document. The HTTP Method Registry shall be created at <http://www.iana.org/assignments/http-methods> and be populated with the registrations below: +---------+------+-------------+ | Method | Safe | Reference | +---------+------+-------------+ | CONNECT | no | Section 6.9 | | DELETE | no | Section 6.7 | | GET | yes | Section 6.3 | | HEAD | yes | Section 6.4 | | OPTIONS | yes | Section 6.2 | | POST | no | Section 6.5 | | PUT | no | Section 6.6 | | TRACE | yes | Section 6.8 | +---------+------+-------------+ 11.2. Status Code Registry The registration procedure for HTTP Status Codes -- previously defined in Section 7.1 of [RFC2817] -- is now defined by Section 4.2 of this document. The HTTP Status Code Registry located at <http://www.iana.org/assignments/http-status-codes> shall be updated with the registrations below: Fielding, et al. Expires September 13, 2012 [Page 49] Internet-Draft HTTP/1.1, Part 2 March 2012 +-------+----------------------------------+----------------+ | Value | Description | Reference | +-------+----------------------------------+----------------+ | 100 | Continue | Section 7.1.1 | | 101 | Switching Protocols | Section 7.1.2 | | 200 | OK | Section 7.2.1 | | 201 | Created | Section 7.2.2 | | 202 | Accepted | Section 7.2.3 | | 203 | Non-Authoritative Information | Section 7.2.4 | | 204 | No Content | Section 7.2.5 | | 205 | Reset Content | Section 7.2.6 | | 300 | Multiple Choices | Section 7.3.1 | | 301 | Moved Permanently | Section 7.3.2 | | 302 | Found | Section 7.3.3 | | 303 | See Other | Section 7.3.4 | | 305 | Use Proxy | Section 7.3.5 | | 306 | (Unused) | Section 7.3.6 | | 307 | Temporary Redirect | Section 7.3.7 | | 400 | Bad Request | Section 7.4.1 | | 402 | Payment Required | Section 7.4.2 | | 403 | Forbidden | Section 7.4.3 | | 404 | Not Found | Section 7.4.4 | | 405 | Method Not Allowed | Section 7.4.5 | | 406 | Not Acceptable | Section 7.4.6 | | 408 | Request Timeout | Section 7.4.7 | | 409 | Conflict | Section 7.4.8 | | 410 | Gone | Section 7.4.9 | | 411 | Length Required | Section 7.4.10 | | 413 | Request Representation Too Large | Section 7.4.11 | | 414 | URI Too Long | Section 7.4.12 | | 415 | Unsupported Media Type | Section 7.4.13 | | 417 | Expectation Failed | Section 7.4.14 | | 426 | Upgrade Required | Section 7.4.15 | | 500 | Internal Server Error | Section 7.5.1 | | 501 | Not Implemented | Section 7.5.2 | | 502 | Bad Gateway | Section 7.5.3 | | 503 | Service Unavailable | Section 7.5.4 | | 504 | Gateway Timeout | Section 7.5.5 | | 505 | HTTP Version Not Supported | Section 7.5.6 | +-------+----------------------------------+----------------+ 11.3. Header Field Registration The Message Header Field Registry located at <http://www.iana.org/ assignments/message-headers/message-header-index.html> shall be updated with the permanent registrations below (see [RFC3864]): Fielding, et al. Expires September 13, 2012 [Page 50] Internet-Draft HTTP/1.1, Part 2 March 2012 +-------------------+----------+----------+---------------+ | Header Field Name | Protocol | Status | Reference | +-------------------+----------+----------+---------------+ | Allow | http | standard | Section 10.1 | | Date | http | standard | Section 10.2 | | Expect | http | standard | Section 10.3 | | From | http | standard | Section 10.4 | | Location | http | standard | Section 10.5 | | Max-Forwards | http | standard | Section 10.6 | | Referer | http | standard | Section 10.7 | | Retry-After | http | standard | Section 10.8 | | Server | http | standard | Section 10.9 | | User-Agent | http | standard | Section 10.10 | +-------------------+----------+----------+---------------+ The change controller is: "IETF (iesg@ietf.org) - Internet Engineering Task Force". 12. Security Considerations This section is meant to inform application developers, information providers, and users of the security limitations in HTTP/1.1 as described by this document. The discussion does not include definitive solutions to the problems revealed, though it does make some suggestions for reducing security risks. 12.1. Transfer of Sensitive Information Like any generic data transfer protocol, HTTP cannot regulate the content of the data that is transferred, nor is there any a priori method of determining the sensitivity of any particular piece of information within the context of any given request. Therefore, applications SHOULD supply as much control over this information as possible to the provider of that information. Four header fields are worth special mention in this context: Server, Via, Referer and From. Revealing the specific software version of the server might allow the server machine to become more vulnerable to attacks against software that is known to contain security holes. Implementors SHOULD make the Server header field a configurable option. Proxies which serve as a portal through a network firewall SHOULD take special precautions regarding the transfer of header information that identifies the hosts behind the firewall. In particular, they SHOULD remove, or replace with sanitized versions, any Via fields generated behind the firewall. The Referer header field allows reading patterns to be studied and Fielding, et al. Expires September 13, 2012 [Page 51] Internet-Draft HTTP/1.1, Part 2 March 2012 reverse links drawn. Although it can be very useful, its power can be abused if user details are not separated from the information contained in the Referer. Even when the personal information has been removed, the Referer header field might indicate a private document's URI whose publication would be inappropriate. The information sent in the From field might conflict with the user's privacy interests or their site's security policy, and hence it SHOULD NOT be transmitted without the user being able to disable, enable, and modify the contents of the field. The user MUST be able to set the contents of this field within a user preference or application defaults configuration. We suggest, though do not require, that a convenient toggle interface be provided for the user to enable or disable the sending of From and Referer information. The User-Agent (Section 10.10) or Server (Section 10.9) header fields can sometimes be used to determine that a specific client or server has a particular security hole which might be exploited. Unfortunately, this same information is often used for other valuable purposes for which HTTP currently has no better mechanism. Furthermore, the User-Agent header field may contain enough entropy to be used, possibly in conjunction with other material, to uniquely identify the user. Some request methods, like TRACE (Section 6.8), expose information that was sent in request header fields within the body of their response. Clients SHOULD be careful with sensitive information, like Cookies, Authorization credentials, and other header fields that might be used to collect data from the client. 12.2. Encoding Sensitive Information in URIs Because the source of a link might be private information or might reveal an otherwise private information source, it is strongly recommended that the user be able to select whether or not the Referer field is sent. For example, a browser client could have a toggle switch for browsing openly/anonymously, which would respectively enable/disable the sending of Referer and From information. Clients SHOULD NOT include a Referer header field in a (non-secure) HTTP request if the referring page was transferred with a secure protocol. Authors of services SHOULD NOT use GET-based forms for the submission Fielding, et al. Expires September 13, 2012 [Page 52] Internet-Draft HTTP/1.1, Part 2 March 2012 of sensitive data because that data will be placed in the request- target. Many existing servers, proxies, and user agents log or display the request-target in places where it might be visible to third parties. Such services can use POST-based form submission instead. 12.3. Location Header Fields: Spoofing and Information Leakage If a single server supports multiple organizations that do not trust one another, then it MUST check the values of Location and Content- Location header fields in responses that are generated under control of said organizations to make sure that they do not attempt to invalidate resources over which they have no authority. Furthermore, appending the fragment identifier from one URI to another one obtained from a Location header field might leak confidential information to the target server -- although the fragment identifier is not transmitted in the final request, it might be visible to the user agent through other means, such as scripting. 12.4. Security Considerations for CONNECT Since tunneled data is opaque to the proxy, there are additional risks to tunneling to other well-known or reserved ports. A HTTP client CONNECTing to port 25 could relay spam via SMTP, for example. As such, proxies SHOULD restrict CONNECT access to a small number of known ports. 13. Acknowledgments See Section 9 of [Part1]. 14. References 14.1. Normative References [Part1] Fielding, R., Ed., Lafon, Y., Ed., and J. Reschke, Ed., "HTTP/1.1, part 1: URIs, Connections, and Message Parsing", draft-ietf-httpbis-p1-messaging-19 (work in progress), March 2012. [Part3] Fielding, R., Ed., Lafon, Y., Ed., and J. Reschke, Ed., "HTTP/1.1, part 3: Message Payload and Content Negotiation", draft-ietf-httpbis-p3-payload-19 (work in progress), March 2012. [Part4] Fielding, R., Ed., Lafon, Y., Ed., and J. Reschke, Ed., "HTTP/1.1, part 4: Conditional Requests", Fielding, et al. Expires September 13, 2012 [Page 53] Internet-Draft HTTP/1.1, Part 2 March 2012 draft-ietf-httpbis-p4-conditional-19 (work in progress), March 2012. [Part5] Fielding, R., Ed., Lafon, Y., Ed., and J. Reschke, Ed., "HTTP/1.1, part 5: Range Requests and Partial Responses", draft-ietf-httpbis-p5-range-19 (work in progress), March 2012. [Part6] Fielding, R., Ed., Lafon, Y., Ed., Nottingham, M., Ed., and J. Reschke, Ed., "HTTP/1.1, part 6: Caching", draft-ietf-httpbis-p6-cache-19 (work in progress), March 2012. [Part7] Fielding, R., Ed., Lafon, Y., Ed., and J. Reschke, Ed., "HTTP/1.1, part 7: Authentication", draft-ietf-httpbis-p7-auth-19 (work in progress), March 2012. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform Resource Identifier (URI): Generic Syntax", STD 66, RFC 3986, January 2005. [RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax Specifications: ABNF", STD 68, RFC 5234, January 2008. 14.2. Informative References [RFC1123] Braden, R., "Requirements for Internet Hosts - Application and Support", STD 3, RFC 1123, October 1989. [RFC1945] Berners-Lee, T., Fielding, R., and H. Nielsen, "Hypertext Transfer Protocol -- HTTP/1.0", RFC 1945, May 1996. [RFC2068] Fielding, R., Gettys, J., Mogul, J., Nielsen, H., and T. Berners-Lee, "Hypertext Transfer Protocol -- HTTP/1.1", RFC 2068, January 1997. [RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H., Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999. [RFC2817] Khare, R. and S. Lawrence, "Upgrading to TLS Within HTTP/1.1", RFC 2817, May 2000. [RFC3864] Klyne, G., Nottingham, M., and J. Mogul, "Registration Fielding, et al. Expires September 13, 2012 [Page 54] Internet-Draft HTTP/1.1, Part 2 March 2012 Procedures for Message Header Fields", BCP 90, RFC 3864, September 2004. [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 5226, May 2008. [RFC5322] Resnick, P., "Internet Message Format", RFC 5322, October 2008. [RFC5789] Dusseault, L. and J. Snell, "PATCH Method for HTTP", RFC 5789, March 2010. [RFC5987] Reschke, J., "Character Set and Language Encoding for Hypertext Transfer Protocol (HTTP) Header Field Parameters", RFC 5987, August 2010. Appendix A. Changes from RFC 2616 This document takes over the Status Code Registry, previously defined in Section 7.1 of [RFC2817]. (Section 4.2) Clarify definition of POST. (Section 6.5) Remove requirement to handle all Content-* header fields; ban use of Content-Range with PUT. (Section 6.6) Take over definition of CONNECT method from [RFC2817]. (Section 6.9) Broadened the definition of 203 (Non-Authoritative Information) to include cases of payload transformations as well. (Section 7.2.4) Status codes 301, 302, and 307: removed the normative requirements on both response payloads and user interaction. (Section 7.3) Failed to consider that there are many other request methods that are safe to automatically redirect, and further that the user agent is able to make that determination based on the request method semantics. Furthermore, allow user agents to rewrite the method from POST to GET for status codes 301 and 302. (Sections 7.3.2, 7.3.3 and 7.3.7) Deprecate 305 Use Proxy status code, because user agents did not implement it. It used to indicate that the target resource must be accessed through the proxy given by the Location field. The Location field gave the URI of the proxy. The recipient was expected to repeat this single request via the proxy. (Section 7.3.5) Fielding, et al. Expires September 13, 2012 [Page 55] Internet-Draft HTTP/1.1, Part 2 March 2012 Define status 426 (Upgrade Required) (this was incorporated from [RFC2817]). (Section 7.4.15) Change ABNF productions for header fields to only define the field value. (Section 10) Reclassify "Allow" as response header field, removing the option to specify it in a PUT request. Relax the server requirement on the contents of the Allow header field and remove requirement on clients to always trust the header field value. (Section 10.1) The ABNF for the Expect header field has been both fixed (allowing parameters for value-less expectations as well) and simplified (allowing trailing semicolons after "100-continue" when they were invalid before). (Section 10.3) Correct syntax of Location header field to allow URI references (including relative references and fragments), as referred symbol "absoluteURI" wasn't what was expected, and add some clarifications as to when use of fragments would not be appropriate. (Section 10.5) Restrict Max-Forwards header field to OPTIONS and TRACE (previously, extension methods could have used it as well). (Section 10.6) Allow Referer field value of "about:blank" as alternative to not specifying it. (Section 10.7) In the description of the Server header field, the Via field was described as a SHOULD. The requirement was and is stated correctly in the description of the Via header field in Section 6.2 of [Part1]. (Section 10.9) Appendix B. Collected ABNF Allow = [ ( "," / method ) *( OWS "," [ OWS method ] ) ] BWS = <BWS, defined in [Part1], Section 3.2.1> Date = HTTP-date Expect = *( "," OWS ) expectation *( OWS "," [ OWS expectation ] ) From = mailbox GMT = %x47.4D.54 ; GMT HTTP-date = rfc1123-date / obs-date Fielding, et al. Expires September 13, 2012 [Page 56] Internet-Draft HTTP/1.1, Part 2 March 2012 Location = URI-reference Max-Forwards = 1*DIGIT OWS = <OWS, defined in [Part1], Section 3.2.1> RWS = <RWS, defined in [Part1], Section 3.2.1> Referer = absolute-URI / partial-URI Retry-After = HTTP-date / delta-seconds Server = product *( RWS ( product / comment ) ) URI-reference = <URI-reference, defined in [Part1], Section 2.7> User-Agent = product *( RWS ( product / comment ) ) absolute-URI = <absolute-URI, defined in [Part1], Section 2.7> asctime-date = day-name SP date3 SP time-of-day SP year comment = <comment, defined in [Part1], Section 3.2.4> date1 = day SP month SP year date2 = day "-" month "-" 2DIGIT date3 = month SP ( 2DIGIT / ( SP DIGIT ) ) day = 2DIGIT day-name = %x4D.6F.6E ; Mon / %x54.75.65 ; Tue / %x57.65.64 ; Wed / %x54.68.75 ; Thu / %x46.72.69 ; Fri / %x53.61.74 ; Sat / %x53.75.6E ; Sun day-name-l = %x4D.6F.6E.64.61.79 ; Monday / %x54.75.65.73.64.61.79 ; Tuesday / %x57.65.64.6E.65.73.64.61.79 ; Wednesday / %x54.68.75.72.73.64.61.79 ; Thursday / %x46.72.69.64.61.79 ; Friday / %x53.61.74.75.72.64.61.79 ; Saturday / %x53.75.6E.64.61.79 ; Sunday delta-seconds = 1*DIGIT expect-name = token expect-param = expect-name [ BWS "=" BWS expect-value ] expect-value = token / quoted-string expectation = expect-name [ BWS "=" BWS expect-value ] *( OWS ";" [ OWS expect-param ] ) hour = 2DIGIT Fielding, et al. Expires September 13, 2012 [Page 57] Internet-Draft HTTP/1.1, Part 2 March 2012 mailbox = <mailbox, defined in [RFC5322], Section 3.4> method = token minute = 2DIGIT month = %x4A.61.6E ; Jan / %x46.65.62 ; Feb / %x4D.61.72 ; Mar / %x41.70.72 ; Apr / %x4D.61.79 ; May / %x4A.75.6E ; Jun / %x4A.75.6C ; Jul / %x41.75.67 ; Aug / %x53.65.70 ; Sep / %x4F.63.74 ; Oct / %x4E.6F.76 ; Nov / %x44.65.63 ; Dec obs-date = rfc850-date / asctime-date obs-text = <obs-text, defined in [Part1], Section 3.2.4> partial-URI = <partial-URI, defined in [Part1], Section 2.7> product = token [ "/" product-version ] product-version = token quoted-string = <quoted-string, defined in [Part1], Section 3.2.4> reason-phrase = *( HTAB / SP / VCHAR / obs-text ) rfc1123-date = day-name "," SP date1 SP time-of-day SP GMT rfc850-date = day-name-l "," SP date2 SP time-of-day SP GMT second = 2DIGIT status-code = 3DIGIT time-of-day = hour ":" minute ":" second token = <token, defined in [Part1], Section 3.2.4> year = 4DIGIT Fielding, et al. Expires September 13, 2012 [Page 58] Internet-Draft HTTP/1.1, Part 2 March 2012 ABNF diagnostics: ; Allow defined but not used ; Date defined but not used ; Expect defined but not used ; From defined but not used ; Location defined but not used ; Max-Forwards defined but not used ; Referer defined but not used ; Retry-After defined but not used ; Server defined but not used ; User-Agent defined but not used ; reason-phrase defined but not used ; status-code defined but not used Appendix C. Change Log (to be removed by RFC Editor before publication) C.1. Since RFC 2616 Extracted relevant partitions from [RFC2616]. C.2. Since draft-ietf-httpbis-p2-semantics-00 Closed issues: o <http://tools.ietf.org/wg/httpbis/trac/ticket/5>: "Via is a MUST" (<http://purl.org/NET/http-errata#via-must>) o <http://tools.ietf.org/wg/httpbis/trac/ticket/6>: "Fragments allowed in Location" (<http://purl.org/NET/http-errata#location-fragments>) o <http://tools.ietf.org/wg/httpbis/trac/ticket/10>: "Safe Methods vs Redirection" (<http://purl.org/NET/http-errata#saferedirect>) o <http://tools.ietf.org/wg/httpbis/trac/ticket/17>: "Revise description of the POST method" (<http://purl.org/NET/http-errata#post>) o <http://tools.ietf.org/wg/httpbis/trac/ticket/35>: "Normative and Informative references" o <http://tools.ietf.org/wg/httpbis/trac/ticket/42>: "RFC2606 Compliance" o <http://tools.ietf.org/wg/httpbis/trac/ticket/65>: "Informative references" Fielding, et al. Expires September 13, 2012 [Page 59] Internet-Draft HTTP/1.1, Part 2 March 2012 o <http://tools.ietf.org/wg/httpbis/trac/ticket/84>: "Redundant cross-references" Other changes: o Move definitions of 304 and 412 condition codes to [Part4] C.3. Since draft-ietf-httpbis-p2-semantics-01 Closed issues: o <http://tools.ietf.org/wg/httpbis/trac/ticket/21>: "PUT side effects" o <http://tools.ietf.org/wg/httpbis/trac/ticket/91>: "Duplicate Host header requirements" Ongoing work on ABNF conversion (<http://tools.ietf.org/wg/httpbis/trac/ticket/36>): o Move "Product Tokens" section (back) into Part 1, as "token" is used in the definition of the Upgrade header field. o Add explicit references to BNF syntax and rules imported from other parts of the specification. o Copy definition of delta-seconds from Part6 instead of referencing it. C.4. Since draft-ietf-httpbis-p2-semantics-02 Closed issues: o <http://tools.ietf.org/wg/httpbis/trac/ticket/24>: "Requiring Allow in 405 responses" o <http://tools.ietf.org/wg/httpbis/trac/ticket/59>: "Status Code Registry" o <http://tools.ietf.org/wg/httpbis/trac/ticket/61>: "Redirection vs. Location" o <http://tools.ietf.org/wg/httpbis/trac/ticket/70>: "Cacheability of 303 response" o <http://tools.ietf.org/wg/httpbis/trac/ticket/76>: "305 Use Proxy" Fielding, et al. Expires September 13, 2012 [Page 60] Internet-Draft HTTP/1.1, Part 2 March 2012 o <http://tools.ietf.org/wg/httpbis/trac/ticket/105>: "Classification for Allow header" o <http://tools.ietf.org/wg/httpbis/trac/ticket/112>: "PUT - 'store under' vs 'store at'" Ongoing work on IANA Message Header Field Registration (<http://tools.ietf.org/wg/httpbis/trac/ticket/40>): o Reference RFC 3984, and update header field registrations for headers defined in this document. Ongoing work on ABNF conversion (<http://tools.ietf.org/wg/httpbis/trac/ticket/36>): o Replace string literals when the string really is case-sensitive (method). C.5. Since draft-ietf-httpbis-p2-semantics-03 Closed issues: o <http://tools.ietf.org/wg/httpbis/trac/ticket/98>: "OPTIONS request bodies" o <http://tools.ietf.org/wg/httpbis/trac/ticket/119>: "Description of CONNECT should refer to RFC2817" o <http://tools.ietf.org/wg/httpbis/trac/ticket/125>: "Location Content-Location reference request/response mixup" Ongoing work on Method Registry (<http://tools.ietf.org/wg/httpbis/trac/ticket/72>): o Added initial proposal for registration process, plus initial content (non-HTTP/1.1 methods to be added by a separate specification). C.6. Since draft-ietf-httpbis-p2-semantics-04 Closed issues: o <http://tools.ietf.org/wg/httpbis/trac/ticket/103>: "Content-*" o <http://tools.ietf.org/wg/httpbis/trac/ticket/132>: "RFC 2822 is updated by RFC 5322" Ongoing work on ABNF conversion Fielding, et al. Expires September 13, 2012 [Page 61] Internet-Draft HTTP/1.1, Part 2 March 2012 (<http://tools.ietf.org/wg/httpbis/trac/ticket/36>): o Use "/" instead of "|" for alternatives. o Introduce new ABNF rules for "bad" whitespace ("BWS"), optional whitespace ("OWS") and required whitespace ("RWS"). o Rewrite ABNFs to spell out whitespace rules, factor out header field value format definitions. C.7. Since draft-ietf-httpbis-p2-semantics-05 Closed issues: o <http://tools.ietf.org/wg/httpbis/trac/ticket/94>: "reason-phrase BNF" Final work on ABNF conversion (<http://tools.ietf.org/wg/httpbis/trac/ticket/36>): o Add appendix containing collected and expanded ABNF, reorganize ABNF introduction. C.8. Since draft-ietf-httpbis-p2-semantics-06 Closed issues: o <http://tools.ietf.org/wg/httpbis/trac/ticket/144>: "Clarify when Referer is sent" o <http://tools.ietf.org/wg/httpbis/trac/ticket/164>: "status codes vs methods" o <http://tools.ietf.org/wg/httpbis/trac/ticket/170>: "Do not require "updates" relation for specs that register status codes or method names" C.9. Since draft-ietf-httpbis-p2-semantics-07 Closed issues: o <http://tools.ietf.org/wg/httpbis/trac/ticket/27>: "Idempotency" o <http://tools.ietf.org/wg/httpbis/trac/ticket/33>: "TRACE security considerations" o <http://tools.ietf.org/wg/httpbis/trac/ticket/110>: "Clarify rules for determining what entities a response carries" Fielding, et al. Expires September 13, 2012 [Page 62] Internet-Draft HTTP/1.1, Part 2 March 2012 o <http://tools.ietf.org/wg/httpbis/trac/ticket/140>: "update note citing RFC 1945 and 2068" o <http://tools.ietf.org/wg/httpbis/trac/ticket/182>: "update note about redirect limit" o <http://tools.ietf.org/wg/httpbis/trac/ticket/191>: "Location header ABNF should use 'URI'" o <http://tools.ietf.org/wg/httpbis/trac/ticket/192>: "fragments in Location vs status 303" o <http://tools.ietf.org/wg/httpbis/trac/ticket/198>: "move IANA registrations for optional status codes" Partly resolved issues: o <http://tools.ietf.org/wg/httpbis/trac/ticket/171>: "Are OPTIONS and TRACE safe?" C.10. Since draft-ietf-httpbis-p2-semantics-08 Closed issues: o <http://tools.ietf.org/wg/httpbis/trac/ticket/10>: "Safe Methods vs Redirection" (we missed the introduction to the 3xx status codes when fixing this previously) C.11. Since draft-ietf-httpbis-p2-semantics-09 Closed issues: o <http://tools.ietf.org/wg/httpbis/trac/ticket/43>: "Fragment combination / precedence during redirects" Partly resolved issues: o <http://tools.ietf.org/wg/httpbis/trac/ticket/185>: "Location header payload handling" o <http://tools.ietf.org/wg/httpbis/trac/ticket/196>: "Term for the requested resource's URI" C.12. Since draft-ietf-httpbis-p2-semantics-10 Closed issues: Fielding, et al. Expires September 13, 2012 [Page 63] Internet-Draft HTTP/1.1, Part 2 March 2012 o <http://tools.ietf.org/wg/httpbis/trac/ticket/69>: "Clarify 'Requested Variant'" o <http://tools.ietf.org/wg/httpbis/trac/ticket/109>: "Clarify entity / representation / variant terminology" o <http://tools.ietf.org/wg/httpbis/trac/ticket/139>: "Methods and Caching" o <http://tools.ietf.org/wg/httpbis/trac/ticket/190>: "OPTIONS vs Max-Forwards" o <http://tools.ietf.org/wg/httpbis/trac/ticket/199>: "Status codes and caching" o <http://tools.ietf.org/wg/httpbis/trac/ticket/220>: "consider removing the 'changes from 2068' sections" C.13. Since draft-ietf-httpbis-p2-semantics-11 Closed issues: o <http://tools.ietf.org/wg/httpbis/trac/ticket/229>: "Considerations for new status codes" o <http://tools.ietf.org/wg/httpbis/trac/ticket/230>: "Considerations for new methods" o <http://tools.ietf.org/wg/httpbis/trac/ticket/232>: "User-Agent guidelines" (relating to the 'User-Agent' header field) C.14. Since draft-ietf-httpbis-p2-semantics-12 Closed issues: o <http://tools.ietf.org/wg/httpbis/trac/ticket/43>: "Fragment combination / precedence during redirects" (added warning about having a fragid on the redirect may cause inconvenience in some cases) o <http://tools.ietf.org/wg/httpbis/trac/ticket/79>: "Content-* vs. PUT" o <http://tools.ietf.org/wg/httpbis/trac/ticket/88>: "205 Bodies" o <http://tools.ietf.org/wg/httpbis/trac/ticket/102>: "Understanding Content-* on non-PUT requests" Fielding, et al. Expires September 13, 2012 [Page 64] Internet-Draft HTTP/1.1, Part 2 March 2012 o <http://tools.ietf.org/wg/httpbis/trac/ticket/103>: "Content-*" o <http://tools.ietf.org/wg/httpbis/trac/ticket/104>: "Header type defaulting" o <http://tools.ietf.org/wg/httpbis/trac/ticket/112>: "PUT - 'store under' vs 'store at'" o <http://tools.ietf.org/wg/httpbis/trac/ticket/137>: "duplicate ABNF for reason-phrase" o <http://tools.ietf.org/wg/httpbis/trac/ticket/180>: "Note special status of Content-* prefix in header registration procedures" o <http://tools.ietf.org/wg/httpbis/trac/ticket/203>: "Max-Forwards vs extension methods" o <http://tools.ietf.org/wg/httpbis/trac/ticket/213>: "What is the value space of HTTP status codes?" (actually fixed in draft-ietf-httpbis-p2-semantics-11) o <http://tools.ietf.org/wg/httpbis/trac/ticket/224>: "Header Classification" o <http://tools.ietf.org/wg/httpbis/trac/ticket/225>: "PUT side effect: invalidation or just stale?" o <http://tools.ietf.org/wg/httpbis/trac/ticket/226>: "proxies not supporting certain methods" o <http://tools.ietf.org/wg/httpbis/trac/ticket/239>: "Migrate CONNECT from RFC2817 to p2" o <http://tools.ietf.org/wg/httpbis/trac/ticket/240>: "Migrate Upgrade details from RFC2817" o <http://tools.ietf.org/wg/httpbis/trac/ticket/267>: "clarify PUT semantics'" o <http://tools.ietf.org/wg/httpbis/trac/ticket/275>: "duplicate ABNF for 'Method'" o <http://tools.ietf.org/wg/httpbis/trac/ticket/276>: "untangle ABNFs for header fields" Fielding, et al. Expires September 13, 2012 [Page 65] Internet-Draft HTTP/1.1, Part 2 March 2012 C.15. Since draft-ietf-httpbis-p2-semantics-13 Closed issues: o <http://tools.ietf.org/wg/httpbis/trac/ticket/276>: "untangle ABNFs for header fields" o <http://tools.ietf.org/wg/httpbis/trac/ticket/251>: "message body in CONNECT request" C.16. Since draft-ietf-httpbis-p2-semantics-14 Closed issues: o <http://tools.ietf.org/wg/httpbis/trac/ticket/255>: "Clarify status code for rate limiting" o <http://tools.ietf.org/wg/httpbis/trac/ticket/294>: "clarify 403 forbidden" o <http://tools.ietf.org/wg/httpbis/trac/ticket/296>: "Clarify 203 Non-Authoritative Information" o <http://tools.ietf.org/wg/httpbis/trac/ticket/298>: "update default reason phrase for 413" C.17. Since draft-ietf-httpbis-p2-semantics-15 Closed issues: o <http://tools.ietf.org/wg/httpbis/trac/ticket/285>: "Strength of requirements on Accept re: 406" o <http://tools.ietf.org/wg/httpbis/trac/ticket/303>: "400 response isn't generic" C.18. Since draft-ietf-httpbis-p2-semantics-16 Closed issues: o <http://tools.ietf.org/wg/httpbis/trac/ticket/160>: "Redirects and non-GET methods" o <http://tools.ietf.org/wg/httpbis/trac/ticket/186>: "Document HTTP's error-handling philosophy" o <http://tools.ietf.org/wg/httpbis/trac/ticket/231>: "Considerations for new headers" Fielding, et al. Expires September 13, 2012 [Page 66] Internet-Draft HTTP/1.1, Part 2 March 2012 o <http://tools.ietf.org/wg/httpbis/trac/ticket/310>: "clarify 303 redirect on HEAD" C.19. Since draft-ietf-httpbis-p2-semantics-17 Closed issues: o <http://tools.ietf.org/wg/httpbis/trac/ticket/185>: "Location header payload handling" o <http://tools.ietf.org/wg/httpbis/trac/ticket/255>: "Clarify status code for rate limiting" (change backed out because a new status code is being defined for this purpose) o <http://tools.ietf.org/wg/httpbis/trac/ticket/312>: "should there be a permanent variant of 307" o <http://tools.ietf.org/wg/httpbis/trac/ticket/325>: "When are Location's semantics triggered?" o <http://tools.ietf.org/wg/httpbis/trac/ticket/327>: "'expect' grammar missing OWS" o <http://tools.ietf.org/wg/httpbis/trac/ticket/329>: "header field considerations: quoted-string vs use of double quotes" C.20. Since draft-ietf-httpbis-p2-semantics-18 Closed issues: o <http://tools.ietf.org/wg/httpbis/trac/ticket/227>: "Combining HEAD responses" o <http://tools.ietf.org/wg/httpbis/trac/ticket/238>: "Requirements for user intervention during redirects" o <http://tools.ietf.org/wg/httpbis/trac/ticket/250>: "message-body in CONNECT response" o <http://tools.ietf.org/wg/httpbis/trac/ticket/295>: "Applying original fragment to 'plain' redirected URI" o <http://tools.ietf.org/wg/httpbis/trac/ticket/302>: "Misplaced text on connection handling in p2" o <http://tools.ietf.org/wg/httpbis/trac/ticket/331>: "clarify that 201 doesn't require Location header fields" Fielding, et al. Expires September 13, 2012 [Page 67] Internet-Draft HTTP/1.1, Part 2 March 2012 o <http://tools.ietf.org/wg/httpbis/trac/ticket/332>: "relax requirements on hypertext in 3/4/5xx error responses" o <http://tools.ietf.org/wg/httpbis/trac/ticket/333>: "example for 426 response should have a payload" o <http://tools.ietf.org/wg/httpbis/trac/ticket/336>: "drop indirection entries for status codes" Index 1 100 Continue (status code) 26 100-continue (expect value) 44 101 Switching Protocols (status code) 27 2 200 OK (status code) 27 201 Created (status code) 27 202 Accepted (status code) 28 203 Non-Authoritative Information (status code) 28 204 No Content (status code) 28 205 Reset Content (status code) 29 3 300 Multiple Choices (status code) 31 301 Moved Permanently (status code) 31 302 Found (status code) 32 303 See Other (status code) 32 305 Use Proxy (status code) 33 306 (Unused) (status code) 33 307 Temporary Redirect (status code) 33 4 400 Bad Request (status code) 33 402 Payment Required (status code) 33 403 Forbidden (status code) 33 404 Not Found (status code) 34 405 Method Not Allowed (status code) 34 406 Not Acceptable (status code) 34 408 Request Timeout (status code) 35 409 Conflict (status code) 35 410 Gone (status code) 35 411 Length Required (status code) 36 413 Request Representation Too Large (status code) 36 414 URI Too Long (status code) 36 415 Unsupported Media Type (status code) 36 417 Expectation Failed (status code) 36 Fielding, et al. Expires September 13, 2012 [Page 68] Internet-Draft HTTP/1.1, Part 2 March 2012 426 Upgrade Required (status code) 37 5 500 Internal Server Error (status code) 37 501 Not Implemented (status code) 37 502 Bad Gateway (status code) 37 503 Service Unavailable (status code) 38 504 Gateway Timeout (status code) 38 505 HTTP Version Not Supported (status code) 38 A Allow header field 42 C CONNECT method 24 D Date header field 42 DELETE method 23 E Expect header field 43 Expect Values 100-continue 44 F From header field 44 G GET method 19 Grammar Allow 42 asctime-date 41 Date 42 date1 40 day 40 day-name 40 day-name-l 40 delta-seconds 47 Expect 43 expect-name 43 expect-param 43 expect-value 43 expectation 43 extension-code 12 From 44 GMT 40 hour 40 Fielding, et al. Expires September 13, 2012 [Page 69] Internet-Draft HTTP/1.1, Part 2 March 2012 HTTP-date 39 Location 45 Max-Forwards 46 method 7 minute 40 month 40 obs-date 40 product 41 product-version 41 reason-phrase 12 Referer 47 Retry-After 47 rfc850-date 41 rfc1123-date 40 second 40 Server 47 status-code 12 time-of-day 40 User-Agent 48 year 40 H HEAD method 19 Header Fields Allow 42 Date 42 Expect 43 From 44 Location 45 Max-Forwards 46 Referer 46 Retry-After 47 Server 47 User-Agent 48 I Idempotent Methods 17 L Location header field 45 M Max-Forwards header field 46 Methods CONNECT 24 DELETE 23 GET 19 HEAD 19 Fielding, et al. Expires September 13, 2012 [Page 70] Internet-Draft HTTP/1.1, Part 2 March 2012 OPTIONS 18 POST 20 PUT 21 TRACE 23 O OPTIONS method 18 P POST method 20 PUT method 21 R Referer header field 46 Retry-After header field 47 S Safe Methods 17 Server header field 47 Status Codes 100 Continue 26 101 Switching Protocols 27 200 OK 27 201 Created 27 202 Accepted 28 203 Non-Authoritative Information 28 204 No Content 28 205 Reset Content 29 300 Multiple Choices 31 301 Moved Permanently 31 302 Found 32 303 See Other 32 305 Use Proxy 33 306 (Unused) 33 307 Temporary Redirect 33 400 Bad Request 33 402 Payment Required 33 403 Forbidden 33 404 Not Found 34 405 Method Not Allowed 34 406 Not Acceptable 34 408 Request Timeout 35 409 Conflict 35 410 Gone 35 411 Length Required 36 413 Request Representation Too Large 36 414 URI Too Long 36 415 Unsupported Media Type 36 Fielding, et al. Expires September 13, 2012 [Page 71] Internet-Draft HTTP/1.1, Part 2 March 2012 417 Expectation Failed 36 426 Upgrade Required 37 500 Internal Server Error 37 501 Not Implemented 37 502 Bad Gateway 37 503 Service Unavailable 38 504 Gateway Timeout 38 505 HTTP Version Not Supported 38 T TRACE method 23 U User-Agent header field 48 Authors' Addresses Roy T. Fielding (editor) Adobe Systems Incorporated 345 Park Ave San Jose, CA 95110 USA EMail: fielding@gbiv.com URI: http://roy.gbiv.com/ Yves Lafon (editor) World Wide Web Consortium W3C / ERCIM 2004, rte des Lucioles Sophia-Antipolis, AM 06902 France EMail: ylafon@w3.org URI: http://www.raubacapeu.net/people/yves/ Fielding, et al. Expires September 13, 2012 [Page 72] Internet-Draft HTTP/1.1, Part 2 March 2012 Julian F. Reschke (editor) greenbytes GmbH Hafenweg 16 Muenster, NW 48155 Germany Phone: +49 251 2807760 Fax: +49 251 2807761 EMail: julian.reschke@greenbytes.de URI: http://greenbytes.de/tech/webdav/ Fielding, et al. 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