INTERNET-DRAFT M. Yevstifeyev Intended Status: Experimental January 8, 2011 Expires: July 12, 2011 HTTP 'Headers-Not-Recognized' Header Field Abstract This document defines mechanism which allows HTTP hosts to notify another hosts about not supported header fields - 'Headers-Not- Recognized' HTTP header field. Status of this Memo This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/1id-abstracts.html The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html Copyright and License Notice Copyright (c) 2011 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must Yevstifeyev Expires July 12, 2011 [Page 1] INTERNET DRAFT Headers-Not-Recognized for HTTP January 8, 2011 include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Motivation . . . . . . . . . . . . . . . . . . . . . . . . 3 1.2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . 3 1.2.1. Conformance Criteria . . . . . . . . . . . . . . . . . 3 1.2.2. Syntax Notation . . . . . . . . . . . . . . . . . . . 3 1.2.3. Terminology . . . . . . . . . . . . . . . . . . . . . 3 2. Technical Overview . . . . . . . . . . . . . . . . . . . . . . . 4 2.1 Model of Work . . . . . . . . . . . . . . . . . . . . . . . 4 2.2 Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5 4. Security Considerations . . . . . . . . . . . . . . . . . . . . 5 5. Normative References . . . . . . . . . . . . . . . . . . . . . . 5 Author's Addresses . . . . . . . . . . . . . . . . . . . . . . . . 6 Yevstifeyev Expires July 12, 2011 [Page 2] INTERNET DRAFT Headers-Not-Recognized for HTTP January 8, 2011 1. Introduction 1.1. Motivation HTTP is one of the most widely-used protocols in the Internet. One of the things which made it so popular is extensibility. One can easily add any header field to the HTTP message. However, all hosts are not able to support all the header fields. Generally, if a it host does not support the header field, it is simply ignored. The another side of exchange is not notified about not processed header fields. This document proposes mechanism which allows HTTP hosts to notify another hosts about not recognized header fields. The proposal is to send an HTTP message with definite header field to the host if one or more header fields of its message are not supported. This document defines 'Headers-Not-Recognized' HTTP header field to be used in such occasion. 1.2. Conventions 1.2.1. Conformance Criteria The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [RFC2119]. 1.2.2. Syntax Notation This specification uses the Augmented Backus-Naur Form (ABNF) notation of [RFC5234]. The construction #element is used as defined in RFC 2616 [RFC2616], Section 2.1. 1.2.3. Terminology HTTP refers to protocol, defined in RFC 2616 [RFC2616] The terms client, server, proxy, gateway and tunnel have the same meaning as in the HTTP/1.1 specification ([RFC2616], Section 1.3). The term host means client or server. Yevstifeyev Expires July 12, 2011 [Page 3] INTERNET DRAFT Headers-Not-Recognized for HTTP January 8, 2011 2. Technical Overview 2.1 Model of Work If the HTTP host receives HTTP message which contains some header fields which are not supported by it, it is RECOMMENDED for it to include the Headers-Not-Recognized header field in the response to the host that sent message with not supported header fields. Information about not supported header fields is to be put in the 'Headers-Not-Recognized' header field following the rules of Section 2.2 of this document. The 'Headers-Not-Recognized' header field MUST contain information only about not supported header fields - i.e. header fields which are not able to be processed anyway. It MUST NOT contain information about header fields, which are partly supported, whose entity cannot be processed while the header field is supported at all, etc. When HTTP host receives HTTP message with Headers-Not-Recognized header field, it is RECOMMENDED that it avoids sending messages with header fields with mentioned in it names to source (for such message) host. Intermediate systems (also called middle-boxes), such as proxies, tunnels, gateways, etc. SHALL transfer the messages with 'Headers- Not-Recognized' header field to the destination host without changing the entity of this header field if the not supported header field was present in the initial HTTP message (i. e. message which intermediate system received before transferring it to destination host), but SHALL omit it if Headers-Not-Recognized header field's entity concerns only to header fields added to initial message by middle- box. If the aforementioned header field concerns added header fields partly, middle-box SHALL change the entity so that it concerns only initial message header field. 2.2 Syntax 'Headers-Not-Recognized' header field has the following format: headers_not_recognized = 1#header_name header_name = 1*VCHAR Yevstifeyev Expires July 12, 2011 [Page 4] INTERNET DRAFT Headers-Not-Recognized for HTTP January 8, 2011 3. IANA Considerations The permanent message header field registry should be updated with the following registration (see [RFC3864]): Header field name Headers-Not-Recognized Applicable protocol http Status experimental Specification document RFC xxxx [RFC Editor: replace xxxx with assigned RFC number] [Note: This registration should take place at http://www.iana.org/assignments/message-headers/perm-headers.html This note is to be deleted upon publication.] 4. Security Considerations This extension to HTTP is not believed to add any additional security concerns not already present in RFC 2616 [RFC2616]. 5. Normative References [RFC2119] S. Bradner, "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 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. [RFC3864] Klyne, G., Nottingham, M., and J. Mogul, "Registration Procedures for Message Header Fields", BCP 90, RFC 3864, September 2004. [RFC5234] Crocker, D., Ed., and P. Overell, "Augmented BNF for Syntax Specifications: ABNF", STD 68, RFC 5234, January 2008. Yevstifeyev Expires July 12, 2011 [Page 5] INTERNET DRAFT Headers-Not-Recognized for HTTP January 8, 2011 Author's Addresses Mykyta Yevstifeyev Kotovsk, Ukraine EMail: evnikita2@gmail.com Yevstifeyev Expires July 12, 2011 [Page 6]