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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 HTTPbis Working Group A. Hutton 3 Internet-Draft Unify 4 Intended status: Standards Track J. Uberti 5 Expires: July 23, 2015 Google 6 M. Thomson 7 Mozilla 8 January 19, 2015 10 The Tunnel-Protocol HTTP Request Header Field 11 draft-ietf-httpbis-tunnel-protocol-01 13 Abstract 15 This specification allows HTTP CONNECT requests to indicate what 16 protocol will be used within the tunnel once established, using the 17 Tunnel-Protocol request header field. 19 Editorial Note (To be removed by RFC Editor) 21 Discussion of this draft takes place on the HTTPBIS working group 22 mailing list (ietf-http-wg@w3.org), which is archived at [1]. 24 Working Group information can be found at [2] and [3]; source code 25 and issues list for this draft can be found at [4]. 27 Status of This Memo 29 This Internet-Draft is submitted in full conformance with the 30 provisions of BCP 78 and BCP 79. 32 Internet-Drafts are working documents of the Internet Engineering 33 Task Force (IETF). Note that other groups may also distribute 34 working documents as Internet-Drafts. The list of current Internet- 35 Drafts is at http://datatracker.ietf.org/drafts/current/. 37 Internet-Drafts are draft documents valid for a maximum of six months 38 and may be updated, replaced, or obsoleted by other documents at any 39 time. It is inappropriate to use Internet-Drafts as reference 40 material or to cite them other than as "work in progress." 42 This Internet-Draft will expire on July 23, 2015. 44 Copyright Notice 46 Copyright (c) 2015 IETF Trust and the persons identified as the 47 document authors. All rights reserved. 49 This document is subject to BCP 78 and the IETF Trust's Legal 50 Provisions Relating to IETF Documents 51 (http://trustee.ietf.org/license-info) in effect on the date of 52 publication of this document. Please review these documents 53 carefully, as they describe your rights and restrictions with respect 54 to this document. Code Components extracted from this document must 55 include Simplified BSD License text as described in Section 4.e of 56 the Trust Legal Provisions and are provided without warranty as 57 described in the Simplified BSD License. 59 Table of Contents 61 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 62 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 63 2. The Tunnel-Protocol HTTP Request Header Field . . . . . . . . 3 64 2.1. Header Field Values . . . . . . . . . . . . . . . . . . . 3 65 2.2. Syntax . . . . . . . . . . . . . . . . . . . . . . . . . 3 66 3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 67 4. Security Considerations . . . . . . . . . . . . . . . . . . . 4 68 5. References . . . . . . . . . . . . . . . . . . . . . . . . . 4 69 5.1. Normative References . . . . . . . . . . . . . . . . . . 5 70 5.2. Informative References . . . . . . . . . . . . . . . . . 5 71 5.3. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 5 73 1. Introduction 75 The HTTP CONNECT method (Section 4.3.6 of [RFC7231]) requests that 76 the recipient establish a tunnel to the identified origin server and 77 thereafter forward packets, in both directions, until the tunnel is 78 closed. Such tunnels are commonly used to create end-to-end virtual 79 connections, through one or more proxies, which may then be secured 80 using TLS (Transport Layer Security, [RFC5246]). 82 The HTTP Tunnel-Protocol header field identifies the protocol that 83 will be spoken within the tunnel, using the application layer next 84 protocol identifier [RFC7301] specified for TLS [RFC5246]. 86 When CONNECT is used to establish a TLS tunnel, the Tunnel-Protocol 87 header field may be used to carry the same application protocol label 88 as will be carried within the TLS handshake. If there are multiple 89 possible application protocols, all of those application protocols 90 are indicated. 92 The Tunnel-Protocol header field carries an indication only. In TLS, 93 the final choice of application protocol is made by the server. 94 Proxies do not implement the tunneled protocol, though they might 95 choose to make policy decisions based on the value of the header 96 field. 98 1.1. Requirements Language 100 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 101 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 102 document are to be interpreted as described in RFC 2119 [RFC2119]. 104 2. The Tunnel-Protocol HTTP Request Header Field 106 Clients include the `Tunnel-Protocol` Request Header field in an HTTP 107 CONNECT request to indicate the application layer protocol will be 108 used within the tunnel, or the set of protocols that might be used 109 within the tunnel. 111 2.1. Header Field Values 113 Valid values for the protocol field are taken from the registry 114 established in [RFC7301]. 116 2.2. Syntax 118 The ABNF (Augmented Backus-Naur Form) syntax for the `Tunnel- 119 Protocol` header field is given below. It is based on the Generic 120 Grammar defined in Section 2 of [RFC7230]. 122 Tunnel-Protocol = "Tunnel-Protocol":" 1#protocol-id 123 protocol-id = token ; percent-encoded ALPN protocol identifier 125 ALPN protocol names are octet sequences with no additional 126 constraints on format. Octets not allowed in tokens ([RFC7230], 127 Section 3.2.6) must be percent-encoded as per Section 2.1 of 128 [RFC3986]. Consequently, the octet representing the percent 129 character "%" (hex 25) must be percent-encoded as well. 131 In order to have precisely one way to represent any ALPN protocol 132 name, the following additional constraints apply: 134 o Octets in the ALPN protocol must not be percent-encoded if they 135 are valid token characters except "%", and 137 o When using percent-encoding, uppercase hex digits must be used. 139 With these constraints, recipients can apply simple string comparison 140 to match protocol identifiers. 142 For example: 144 CONNECT www.example.com HTTP/1.1 145 Host: www.example.com 146 Tunnel-Protocol: h2, http%2F1.1 148 3. IANA Considerations 150 HTTP header fields are registered within the "Message Headers" 151 registry maintained at [5]. This document defines and registers the 152 `Tunnel-Protocol` header field, according to [RFC3864] as follows: 154 Header Field Name: Tunnel-Protocol 156 Protocol: http 158 Status: Standard 160 Reference: Section 2 162 Change Controller: IETF (iesg@ietf.org) - Internet Engineering Task 163 Force 165 4. Security Considerations 167 In case of using HTTP CONNECT to a TURN server the security 168 considerations of Section 4.3.6 of [RFC7231] apply. It states that 169 there "are significant risks in establishing a tunnel to arbitrary 170 servers, particularly when the destination is a well-known or 171 reserved TCP port that is not intended for Web traffic. Proxies that 172 support CONNECT SHOULD restrict its use to a limited set of known 173 ports or a configurable whitelist of safe request targets." 175 The `Tunnel-Protocol` request header field described in this document 176 is an optional header. Clients and HTTP Proxies could choose to not 177 support the header and therefore fail to provide it, or ignore it 178 when present. If the header is not available or ignored, a proxy 179 cannot identify the purpose of the tunnel and use this as input to 180 any authorization decision regarding the tunnel. This is 181 indistinguishable from the case where either client or proxy does not 182 support the `Tunnel-Protocol` header. 184 5. References 185 5.1. Normative References 187 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 188 Requirement Levels", BCP 14, RFC 2119, March 1997. 190 [RFC3864] Klyne, G., Nottingham, M., and J. Mogul, "Registration 191 Procedures for Message Header Fields", BCP 90, RFC 3864, 192 September 2004. 194 [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform 195 Resource Identifier (URI): Generic Syntax", STD 66, RFC 196 3986, January 2005. 198 [RFC7230] Fielding, R. and J. Reschke, "Hypertext Transfer Protocol 199 (HTTP/1.1): Message Syntax and Routing", RFC 7230, June 200 2014. 202 [RFC7231] Fielding, R. and J. Reschke, "Hypertext Transfer Protocol 203 (HTTP/1.1): Semantics and Content", RFC 7231, June 2014. 205 [RFC7301] Friedl, S., Popov, A., Langley, A., and E. Stephan, 206 "Transport Layer Security (TLS) Application-Layer Protocol 207 Negotiation Extension", RFC 7301, July 2014. 209 5.2. Informative References 211 [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security 212 (TLS) Protocol Version 1.2", RFC 5246, August 2008. 214 5.3. URIs 216 [1] https://www.iana.org/assignments/message-headers 218 Authors' Addresses 220 Andrew Hutton 221 Unify 222 Technology Drive 223 Nottingham NG9 1LA 224 UK 226 EMail: andrew.hutton@unify.com 227 Justin Uberti 228 Google 229 747 6th Ave S 230 Kirkland, WA 98033 231 US 233 EMail: justin@uberti.name 235 Martin Thomson 236 Mozilla 237 331 E Evelyn Street 238 Mountain View, CA 94041 239 US 241 EMail: martin.thomson@gmail.com