draft-ietf-httpbis-tunnel-protocol-01.txt   draft-ietf-httpbis-tunnel-protocol-02.txt 
HTTPbis 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: July 23, 2015 Google Expires: September 25, 2015 Google
M. Thomson M. Thomson
Mozilla Mozilla
January 19, 2015 March 24, 2015
The Tunnel-Protocol HTTP Request Header Field The Tunnel-Protocol HTTP Header Field
draft-ietf-httpbis-tunnel-protocol-01 draft-ietf-httpbis-tunnel-protocol-02
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
Tunnel-Protocol request header field. Tunnel-Protocol header field.
Editorial Note (To be removed by RFC Editor) Editorial Note (To be removed by RFC Editor)
Discussion of this draft takes place on the HTTPBIS working group Discussion of this draft takes place on the HTTPBIS working group
mailing list (ietf-http-wg@w3.org), which is archived at [1]. mailing list (ietf-http-wg@w3.org), which is archived at [1].
Working Group information can be found at [2] and [3]; source code Working Group information can be found at [2] and [3]; source code
and issues list for this draft can be found at [4]. and issues list for this draft can be found at [4].
Status of This Memo Status of This Memo
skipping to change at page 1, line 43 skipping to change at page 1, line 43
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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This Internet-Draft will expire on July 23, 2015. This Internet-Draft will expire on September 25, 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
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
2. The Tunnel-Protocol HTTP Request Header Field . . . . . . . . 3 2. The Tunnel-Protocol HTTP Header Field . . . . . . . . . . . . 3
2.1. Header Field Values . . . . . . . . . . . . . . . . . . . 3 2.1. Header Field Values . . . . . . . . . . . . . . . . . . . 3
2.2. Syntax . . . . . . . . . . . . . . . . . . . . . . . . . 3 2.2. Syntax . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
4. Security Considerations . . . . . . . . . . . . . . . . . . . 4 4. Security Considerations . . . . . . . . . . . . . . . . . . . 4
5. References . . . . . . . . . . . . . . . . . . . . . . . . . 4 5. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
5.1. Normative References . . . . . . . . . . . . . . . . . . 5 5.1. Normative References . . . . . . . . . . . . . . . . . . 5
5.2. Informative References . . . . . . . . . . . . . . . . . 5 5.2. Informative References . . . . . . . . . . . . . . . . . 5
5.3. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 5 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, which may then be secured connections, through one or more proxies.
using TLS (Transport Layer Security, [RFC5246]).
The HTTP Tunnel-Protocol header field identifies the protocol that The HTTP Tunnel-Protocol header field identifies the protocol that
will be spoken within the tunnel, using the application layer next will be spoken within the tunnel, using the Application Layer
protocol identifier [RFC7301] specified for TLS [RFC5246]. Protocol Negotiation identifier (ALPN, [RFC7301]).
When CONNECT is used to establish a TLS tunnel, the Tunnel-Protocol When the CONNECT method is used to establish a tunnel, the Tunnel-
header field may be used to carry the same application protocol label Protocol header field can be used to identify the protocol that the
as will be carried within the TLS handshake. If there are multiple client intends to use with that tunnel. For a tunnel that is then
possible application protocols, all of those application protocols secured using TLS [RFC5246], the header field carries the same
are indicated. 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 of client
intent only. In TLS, the final choice of application protocol is
made by the server from the set of choices presented by the client.
Other protocols could negotiate protocols differently.
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 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. field. For example, a proxy could use the application protocol to
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
document are to be interpreted as described in RFC 2119 [RFC2119]. document are to be interpreted as described in RFC 2119 [RFC2119].
2. The Tunnel-Protocol HTTP Request Header Field 2. The Tunnel-Protocol HTTP Header Field
Clients include the `Tunnel-Protocol` Request Header field in an HTTP Clients include the Tunnel-Protocol header field in an HTTP CONNECT
CONNECT request to indicate the application layer protocol will be request to indicate the application layer protocol that will be used
used within the tunnel, or the set of protocols that might be used within the tunnel, or the set of protocols that might be used within
within the tunnel. the tunnel.
2.1. Header Field Values 2.1. Header Field Values
Valid values for the protocol field are taken from the registry Valid values for the protocol field are taken from the "Application-
established in [RFC7301]. Layer Protocol Negotiation (ALPN) Protocol ID" registry ([5])
established by [RFC7301].
2.2. Syntax 2.2. Syntax
The ABNF (Augmented Backus-Naur Form) syntax for the `Tunnel- The ABNF (Augmented Backus-Naur Form) syntax for the Tunnel-Protocol
Protocol` header field is given below. It is based on the Generic header field is given below. It is based on the Generic Grammar
Grammar defined in Section 2 of [RFC7230]. defined in Section 2 of [RFC7230].
Tunnel-Protocol = "Tunnel-Protocol":" 1#protocol-id Tunnel-Protocol = "Tunnel-Protocol":" 1#protocol-id
protocol-id = token ; percent-encoded ALPN protocol identifier protocol-id = token ; percent-encoded ALPN protocol identifier
ALPN protocol names are octet sequences with no additional ALPN protocol names are octet sequences with no additional
constraints on format. Octets not allowed in tokens ([RFC7230], constraints on format. Octets not allowed in tokens ([RFC7230],
Section 3.2.6) must be percent-encoded as per Section 2.1 of Section 3.2.6) MUST be percent-encoded as per Section 2.1 of
[RFC3986]. Consequently, the octet representing the percent [RFC3986]. Consequently, the octet representing the percent
character "%" (hex 25) must be percent-encoded as well. character "%" (hex 25) MUST be percent-encoded as well.
In order to have precisely one way to represent any ALPN protocol In order to have precisely one way to represent any ALPN protocol
name, the following additional constraints apply: name, the following additional constraints apply:
o Octets in the ALPN protocol must not be percent-encoded if they o Octets in the ALPN protocol MUST NOT be percent-encoded if they
are valid token characters except "%", and are valid token characters except "%", and
o When using percent-encoding, uppercase hex digits must be used. o When using percent-encoding, uppercase hex digits MUST be used.
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
Tunnel-Protocol: h2, http%2F1.1 Tunnel-Protocol: h2, http%2F1.1
3. IANA Considerations 3. IANA Considerations
HTTP header fields are registered within the "Message Headers" HTTP header fields are registered within the "Message Headers"
registry maintained at [5]. This document defines and registers the registry maintained at [6]. This document defines and registers the
`Tunnel-Protocol` header field, according to [RFC3864] as follows: Tunnel-Protocol header field, according to [RFC3864] as follows:
Header Field Name: Tunnel-Protocol Header Field Name: Tunnel-Protocol
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
Force Force
4. Security Considerations 4. Security Considerations
In case of using HTTP CONNECT to a TURN server the security In case of using HTTP CONNECT to a TURN server ("Traversal Using
considerations of Section 4.3.6 of [RFC7231] apply. It states that Relays around NAT", [RFC5766]) the security considerations of
there "are significant risks in establishing a tunnel to arbitrary Section 4.3.6 of [RFC7231] apply. It states that there "are
servers, particularly when the destination is a well-known or significant risks in establishing a tunnel to arbitrary servers,
reserved TCP port that is not intended for Web traffic. Proxies that particularly when the destination is a well-known or reserved TCP
support CONNECT SHOULD restrict its use to a limited set of known port that is not intended for Web traffic. Proxies that support
ports or a configurable whitelist of safe request targets." 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 The Tunnel-Protocol header field described in this document is an
is an optional header. Clients and HTTP Proxies could choose to not OPTIONAL header field. Clients and HTTP proxies could choose to not
support the header and therefore fail to provide it, or ignore it support the header and therefore fail to provide it, or ignore it
when present. If the header is not available or ignored, a proxy 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 cannot identify the purpose of the tunnel and use this as input to
any authorization decision regarding the tunnel. This is any authorization decision regarding the tunnel. This is
indistinguishable from the case where either client or proxy does not indistinguishable from the case where either client or proxy does not
support the `Tunnel-Protocol` header. support the Tunnel-Protocol header field.
The value of the Tunnel-Protocol header field could be falsified by a
client. If the data being sent through the tunnel is encrypted (for
example, with TLS [RFC5246]), then the proxy might not be able to
directly inspect the data to verify that the claimed protocol is the
one which is actually being used, though a proxy might be able to
perform traffic analysis [TRAFFIC]. A proxy therefore cannot rely on
the value of the Tunnel-Protocol header field as a policy input in
all cases.
5. References 5. References
5.1. Normative References 5.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[RFC3864] Klyne, G., Nottingham, M., and J. Mogul, "Registration [RFC3864] Klyne, G., Nottingham, M., and J. Mogul, "Registration
Procedures for Message Header Fields", BCP 90, RFC 3864, Procedures for Message Header Fields", BCP 90, RFC 3864,
September 2004. September 2004, <http://www.rfc-editor.org/info/rfc3864>.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66, RFC Resource Identifier (URI): Generic Syntax", STD 66, RFC
3986, January 2005. 3986, January 2005,
<http://www.rfc-editor.org/info/rfc3986>.
[RFC7230] Fielding, R. and J. Reschke, "Hypertext Transfer Protocol [RFC7230] Fielding, R. and J. Reschke, "Hypertext Transfer Protocol
(HTTP/1.1): Message Syntax and Routing", RFC 7230, June (HTTP/1.1): Message Syntax and Routing", RFC 7230, June
2014. 2014, <http://www.rfc-editor.org/info/rfc7230>.
[RFC7231] Fielding, R. and J. Reschke, "Hypertext Transfer Protocol [RFC7231] Fielding, R. and J. Reschke, "Hypertext Transfer Protocol
(HTTP/1.1): Semantics and Content", RFC 7231, June 2014. (HTTP/1.1): Semantics and Content", RFC 7231, June 2014,
<http://www.rfc-editor.org/info/rfc7231>.
[RFC7301] Friedl, S., Popov, A., Langley, A., and E. Stephan, [RFC7301] Friedl, S., Popov, A., Langley, A., and E. Stephan,
"Transport Layer Security (TLS) Application-Layer Protocol "Transport Layer Security (TLS) Application-Layer Protocol
Negotiation Extension", RFC 7301, July 2014. Negotiation Extension", RFC 7301, July 2014,
<http://www.rfc-editor.org/info/rfc7301>.
5.2. Informative References 5.2. Informative References
[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.2", RFC 5246, August 2008. (TLS) Protocol Version 1.2", RFC 5246, August 2008,
<http://www.rfc-editor.org/info/rfc5246>.
[RFC5766] Mahy, R., Matthews, P., and J. Rosenberg, "Traversal Using
Relays around NAT (TURN): Relay Extensions to Session
Traversal Utilities for NAT (STUN)", RFC 5766, April 2010,
<http://www.rfc-editor.org/info/rfc5766>.
[TRAFFIC] Pironti, A., Strub, P-Y., and K. Bhargavan, "Website Users
by TLS Traffic Analysis: New Attacks and Effective
Countermeasures, Revision 1", 2012,
<https://alfredo.pironti.eu/research/publications/full/
identifying-website-users-tls-traffic-analysis-new-
attacks-and-effective-counterme>.
5.3. URIs 5.3. URIs
[1] https://www.iana.org/assignments/message-headers [1] http://www.iana.org/assignments/tls-extensiontype-values/#alpn-
protocol-ids
[2] https://www.iana.org/assignments/message-headers
Authors' Addresses Authors' Addresses
Andrew Hutton Andrew Hutton
Unify Unify
Technology Drive Technology Drive
Nottingham NG9 1LA Nottingham NG9 1LA
UK UK
EMail: andrew.hutton@unify.com EMail: andrew.hutton@unify.com
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