HTTPbis Working Group A. Hutton Internet-Draft Unify Intended status: Standards Track J. Uberti Expires: July 23, 2015 Google M. Thomson Mozilla January 19, 2015 The Tunnel-Protocol HTTP Request Header Field draft-ietf-httpbis-tunnel-protocol-latest Abstract This specification allows HTTP CONNECT requests to indicate what protocol will be used within the tunnel once established, using the Tunnel-Protocol request header field. Editorial Note (To be removed by RFC Editor) Discussion of this draft takes place on the HTTPBIS working group mailing list (ietf-http-wg@w3.org), which is archived at . Working Group information can be found at and ; source code and issues list for this draft can be found at . Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. 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." This Internet-Draft will expire on July 23, 2015. Copyright Notice Hutton, et al. Expires July 23, 2015 [Page 1] Internet-Draft Tunnel-Protocol January 2015 Copyright (c) 2015 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 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. Requirements Language . . . . . . . . . . . . . . . . . . . 3 2. The Tunnel-Protocol HTTP Request Header Field . . . . . . . . . 3 2.1. Header Field Values . . . . . . . . . . . . . . . . . . . . 3 2.2. Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 4 4. Security Considerations . . . . . . . . . . . . . . . . . . . . 5 5. References . . . . . . . . . . . . . . . . . . . . . . . . . . 5 5.1. Normative References . . . . . . . . . . . . . . . . . . . 5 5.2. Informative References . . . . . . . . . . . . . . . . . . 6 Hutton, et al. Expires July 23, 2015 [Page 2] Internet-Draft Tunnel-Protocol January 2015 1. Introduction The HTTP CONNECT method (Section 4.3.6 of [RFC7231]) requests that the recipient establish a tunnel to the identified origin server and thereafter forward packets, in both directions, until the tunnel is closed. Such tunnels are commonly used to create end-to-end virtual connections, through one or more proxies, which may then be secured using TLS (Transport Layer Security, [RFC5246]). The HTTP Tunnel-Protocol header field identifies the protocol that will be spoken within the tunnel, using the application layer next protocol identifier [RFC7301] specified for TLS [RFC5246]. When CONNECT is used to establish a TLS tunnel, the Tunnel-Protocol header field may be used to carry the same application protocol label as will be carried within the TLS handshake. If there are multiple possible application protocols, all of those application protocols are indicated. The Tunnel-Protocol header field carries an indication only. In TLS, the final choice of application protocol is made by the server. Proxies do not implement the tunneled protocol, though they might choose to make policy decisions based on the value of the header field. 1.1. Requirements Language 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]. 2. The Tunnel-Protocol HTTP Request Header Field Clients include the `Tunnel-Protocol` Request Header field in an HTTP CONNECT request to indicate the application layer protocol will be used within the tunnel, or the set of protocols that might be used within the tunnel. 2.1. Header Field Values Valid values for the protocol field are taken from the registry established in [RFC7301]. 2.2. Syntax The ABNF (Augmented Backus-Naur Form) syntax for the `Tunnel- Protocol` header field is given below. It is based on the Generic Grammar defined in Section 2 of [RFC7230]. Hutton, et al. Expires July 23, 2015 [Page 3] Internet-Draft Tunnel-Protocol January 2015 Tunnel-Protocol = "Tunnel-Protocol":" 1#protocol-id protocol-id = token ; percent-encoded ALPN protocol identifier ALPN protocol names are octet sequences with no additional constraints on format. Octets not allowed in tokens ([RFC7230], Section 3.2.6) must be percent-encoded as per Section 2.1 of [RFC3986]. Consequently, the octet representing the percent character "%" (hex 25) must be percent-encoded as well. In order to have precisely one way to represent any ALPN protocol name, the following additional constraints apply: o Octets in the ALPN protocol must not be percent-encoded if they are valid token characters except "%", and o When using percent-encoding, uppercase hex digits must be used. With these constraints, recipients can apply simple string comparison to match protocol identifiers. For example: CONNECT www.example.com HTTP/1.1 Host: www.example.com Tunnel-Protocol: h2, http%2F1.1 3. IANA Considerations HTTP header fields are registered within the "Message Headers" registry maintained at . This document defines and registers the `Tunnel-Protocol` header field, according to [RFC3864] as follows: Header Field Name: Tunnel-Protocol Protocol: http Status: Standard Reference: Section 2 Change Controller: IETF (iesg@ietf.org) - Internet Engineering Task Force Hutton, et al. Expires July 23, 2015 [Page 4] Internet-Draft Tunnel-Protocol January 2015 4. Security Considerations In case of using HTTP CONNECT to a TURN server the security considerations of Section 4.3.6 of [RFC7231] apply. It states that there "are significant risks in establishing a tunnel to arbitrary servers, particularly when the destination is a well-known or reserved TCP port that is not intended for Web traffic. Proxies that support CONNECT SHOULD restrict its use to a limited set of known ports or a configurable whitelist of safe request targets." The `Tunnel-Protocol` request header field described in this document is an optional header. Clients and HTTP Proxies could choose to not support the header and therefore fail to provide it, or ignore it when present. If the header is not available or ignored, a proxy cannot identify the purpose of the tunnel and use this as input to any authorization decision regarding the tunnel. This is indistinguishable from the case where either client or proxy does not support the `Tunnel-Protocol` header. 5. References 5.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997, . [RFC3864] Klyne, G., Nottingham, M., and J. Mogul, "Registration Procedures for Message Header Fields", BCP 90, RFC 3864, September 2004, . [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform Resource Identifier (URI): Generic Syntax", STD 66, RFC 3986, January 2005, . [RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing", RFC 7230, June 2014, . [RFC7231] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content", RFC 7231, June 2014, . [RFC7301] Friedl, S., Popov, A., Langley, A., and E. Stephan, "Transport Layer Security (TLS) Application-Layer Protocol Negotiation Extension", RFC 7301, July 2014, Hutton, et al. Expires July 23, 2015 [Page 5] Internet-Draft Tunnel-Protocol January 2015 . 5.2. Informative References [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security (TLS) Protocol Version 1.2", RFC 5246, August 2008, . Authors' Addresses Andrew Hutton Unify Technology Drive Nottingham NG9 1LA UK EMail: andrew.hutton@unify.com Justin Uberti Google 747 6th Ave S Kirkland, WA 98033 US EMail: justin@uberti.name Martin Thomson Mozilla 331 E Evelyn Street Mountain View, CA 94041 US EMail: martin.thomson@gmail.com Hutton, et al. Expires July 23, 2015 [Page 6]