draft-ietf-httpbis-tunnel-protocol-03.txt   draft-ietf-httpbis-tunnel-protocol-04.txt 
HTTP Working Group A. Hutton HTTP Working Group A. Hutton
Internet-Draft Unify Internet-Draft Unify
Intended status: Standards Track J. Uberti Intended status: Standards Track J. Uberti
Expires: October 20, 2015 Google Expires: November 21, 2015 Google
M. Thomson M. Thomson
Mozilla Mozilla
April 18, 2015 May 20, 2015
The ALPN HTTP Header Field The ALPN HTTP Header Field
draft-ietf-httpbis-tunnel-protocol-03 draft-ietf-httpbis-tunnel-protocol-04
Abstract Abstract
This specification allows HTTP CONNECT requests to indicate what This specification allows HTTP CONNECT requests to indicate what
protocol will be used within the tunnel once established, using the protocol will be used within the tunnel once established, using the
ALPN header field. ALPN 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 [1].
Working Group information can be found at [2] and [3]; source code
and issues list for this draft can be found at [4].
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on October 20, 2015. This Internet-Draft will expire on November 21, 2015.
Copyright Notice Copyright Notice
Copyright (c) 2015 IETF Trust and the persons identified as the Copyright (c) 2015 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
2. The ALPN HTTP Header Field . . . . . . . . . . . . . . . . . 3 2. The ALPN HTTP Header Field . . . . . . . . . . . . . . . . . 3
2.1. Header Field Values . . . . . . . . . . . . . . . . . . . 3 2.1. Header Field Values . . . . . . . . . . . . . . . . . . . 3
2.2. Syntax . . . . . . . . . . . . . . . . . . . . . . . . . 3 2.2. Syntax . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.3. Usage . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
4. Security Considerations . . . . . . . . . . . . . . . . . . . 4 4. Security Considerations . . . . . . . . . . . . . . . . . . . 4
5. References . . . . . . . . . . . . . . . . . . . . . . . . . 5 5. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
5.1. Normative References . . . . . . . . . . . . . . . . . . 5 5.1. Normative References . . . . . . . . . . . . . . . . . . 5
5.2. Informative References . . . . . . . . . . . . . . . . . 5 5.2. Informative References . . . . . . . . . . . . . . . . . 6
5.3. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 6 5.3. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction 1. Introduction
The HTTP CONNECT method (Section 4.3.6 of [RFC7231]) requests that The HTTP CONNECT method (Section 4.3.6 of [RFC7231]) requests that
the recipient establish a tunnel to the identified origin server and the recipient establish a tunnel to the identified origin server and
thereafter forward packets, in both directions, until the tunnel is thereafter forward packets, in both directions, until the tunnel is
closed. Such tunnels are commonly used to create end-to-end virtual closed. Such tunnels are commonly used to create end-to-end virtual
connections, through one or more proxies. connections, through one or more proxies.
The HTTP ALPN header field identifies the protocol that will be The HTTP ALPN header field identifies the protocol that will be used
spoken within the tunnel, using the Application Layer Protocol within the tunnel, using the Application Layer Protocol Negotiation
Negotiation identifier (ALPN, [RFC7301]). identifier (ALPN, [RFC7301]).
When the CONNECT method is used to establish a tunnel, the ALPN When the CONNECT method is used to establish a tunnel, the ALPN
header field can be used to identify the protocol that the client header field can be used to identify the protocol that the client
intends to use with that tunnel. For a tunnel that is then secured intends to use with that tunnel. For a tunnel that is then secured
using TLS [RFC5246], the header field carries the same application using TLS [RFC5246], the header field carries the same application
protocol label as will be carried within the TLS handshake. If there protocol label as will be carried within the TLS handshake. If there
are multiple possible application protocols, all of those application are multiple possible application protocols, all of those application
protocols are indicated. protocols are indicated.
The ALPN header field carries an indication of client intent only. The ALPN header field carries an indication of client intent only.
In TLS, the final choice of application protocol is made by the An ALPN identifier is used here only to identify the application
server from the set of choices presented by the client. Other protocol or suite of protocols that the client intends to use in the
protocols could negotiate protocols differently. tunnel. No negotiation takes place using this header field. In TLS,
the final choice of application protocol is made by the server from
the set of choices presented by the client. Other substrates could
negotiate the application protocol differently.
Proxies do not implement the tunneled protocol, though they might Proxies do not implement the tunneled protocol, though they might
choose to make policy decisions based on the value of the header choose to make policy decisions based on the value of the header
field. For example, a proxy could use the application protocol to field. For example, a proxy could use the application protocol to
select appropriate traffic prioritization. select appropriate traffic prioritization.
1.1. Requirements Language 1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
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2. The ALPN HTTP Header Field 2. The ALPN HTTP Header Field
Clients include the ALPN header field in an HTTP CONNECT request to Clients include the ALPN header field in an HTTP CONNECT request to
indicate the application layer protocol that will be used within the indicate the application layer protocol that will be used within the
tunnel, or the set of protocols that might be used within the tunnel. tunnel, or the set of protocols that might be used within the tunnel.
2.1. Header Field Values 2.1. Header Field Values
Valid values for the protocol field are taken from the "Application- Valid values for the protocol field are taken from the "Application-
Layer Protocol Negotiation (ALPN) Protocol ID" registry ([5]) Layer Protocol Negotiation (ALPN) Protocol ID" registry ([1])
established by [RFC7301]. established by [RFC7301].
2.2. Syntax 2.2. Syntax
The ABNF (Augmented Backus-Naur Form) syntax for the ALPN header The ABNF (Augmented Backus-Naur Form) syntax for the ALPN header
field is given below. It is based on the Generic Grammar defined in field is given below. It is based on the Generic Grammar defined in
Section 2 of [RFC7230]. Section 2 of [RFC7230].
ALPN = "ALPN":" 1#protocol-id ALPN = "ALPN":" 1#protocol-id
protocol-id = token ; percent-encoded ALPN protocol identifier protocol-id = token ; percent-encoded ALPN protocol identifier
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With these constraints, recipients can apply simple string comparison With these constraints, recipients can apply simple string comparison
to match protocol identifiers. to match protocol identifiers.
For example: For example:
CONNECT www.example.com HTTP/1.1 CONNECT www.example.com HTTP/1.1
Host: www.example.com Host: www.example.com
ALPN: h2, http%2F1.1 ALPN: h2, http%2F1.1
2.3. Usage
For a CONNECT tunnel that conveys a TLS session that in turn
encapsulates another protocol, the value of the ALPN header field
contains the same list of ALPN identifiers that will be sent in the
TLS ClientHello message [RFC7301].
Where no protocol negotiation is expected to occur, such as in
protocols that do not use TLS, the ALPN header field contains a
single ALPN Protocol Identifier corresponding to the application
protocol that is intended to be used. If an alternative form of
protocol negotiation is possible, the ALPN header field contains the
set of protocols that might be negotiated.
When used in the ALPN header field, the ALPN identifier and registry
are used to identify an entire application protocol stack, not a
single protocol layer or component.
3. IANA Considerations 3. IANA Considerations
HTTP header fields are registered within the "Message Headers" HTTP header fields are registered within the "Permanent Message
registry maintained at [6]. This document defines and registers the Header Field Names" registry maintained at [2]. This document
ALPN header field, according to [RFC3864] as follows: defines and registers the ALPN header field, according to [RFC3864]
as follows:
Header Field Name: ALPN Header Field Name: ALPN
Protocol: http Protocol: http
Status: Standard Status: Standard
Reference: Section 2 Reference: Section 2
Change Controller: IETF (iesg@ietf.org) - Internet Engineering Task Change Controller: IETF (iesg@ietf.org) - Internet Engineering Task
 End of changes. 12 change blocks. 
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