Internet Engineering Task Force A. Hutton
Internet-Draft Unify
Intended status: Standards Track J. Uberti
Expires: December 29, 2014 Google
M. Thomson
Mozilla
June 27, 2014
HTTP Connect - Tunnel Protocol For WebRTC
draft-hutton-httpbis-connect-protocol-00
Abstract
This document describes a mechanism to enable HTTP Clients to provide
an indication within a HTTP Connect request as to which protocol will
be used within the tunnel established to the Server identified by the
target resource. The tunneled protocol is declared using the Tunnel-
Protocol HTTP Request header field. Label usage relating to the use
of HTTP Connect by WebRTC clients (e.g. turn, webrtc) are described
in this document.
Status of This Memo
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This Internet-Draft will expire on December 29, 2014.
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carefully, as they describe your rights and restrictions with respect
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
2. Use Cases . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. The Tunnel-Protocol HTTP Request Header Field . . . . . . . . 3
3.1. Header Field Values . . . . . . . . . . . . . . . . . . . 3
3.2. Syntax . . . . . . . . . . . . . . . . . . . . . . . . . 4
3.3. TURN as the Tunnel Protocol . . . . . . . . . . . . . . . 4
3.4. ICE-TCP / WebRTC as the Tunnel Protocol . . . . . . . . . 4
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
5. Security Considerations . . . . . . . . . . . . . . . . . . . 5
6. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
6.1. Normative References . . . . . . . . . . . . . . . . . . 5
6.2. Informative References . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction
The HTTP Connect method (Section 4.3.6 of [RFC7231]) requests that
the recipient establish a tunnel to the destination origin server
identified by the request-target 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 RTCWEB use cases and requirements document
[I-D.ietf-rtcweb-use-cases-and-requirements] includes a requirement
that a WebRTC Client must be able to send streams and data to a peer
in the presence of Firewalls that only allow traffic via a HTTP
Proxy, when Firewall policy allows WebRTC traffic. To facilitate
this and to allow such a HTTP Proxy to be provided with an indication
that WebRTC related real-time media is to be included in the tunnel
this specification defines the Tunnel-Protocol Request header field
and associated labels. This allows the proxy to identify the
protocol being used in the tunnel as early as possible therefore
enabling the proxy to make informed policy decisions. The type of
policy decisions the proxy may make is not specified here but may
include rejecting the request with a HTTP status code responses or
prioritizing connections. As described in Section 4.3.6 of [RFC7231]
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and 2xx response indicates consent for the client to switch to tunnel
mode.
The HTTP Tunnel-Protocol header field may be used in conjunction with
and complements the application layer next protocol extension
[I-D.ietf-tls-applayerprotoneg] specified for TLS [RFC5246]". In the
scenario where the HTTP Connect is used to establish a TLS tunnel
then the HTTP Tunnel-Protocol may be used to carry the same next
protocol label as carried within the TLS handshake. However, the
Tunnel-Protocol is an indication rather a negotiation since the HTTP
Proxy does not implement the tunneled protocol. ALPN Labels are
already defined for TURN in [I-D.patil-tram-alpn] and WebRTC
[I-D.thomson-rtcweb-alpn] and are re-used here.
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. Use Cases
The following two use cases are considered:
o The WebRTC Client issues a HTTP CONNECT request to the HTTP proxy
with the TURN server address in the Request URI.
o The WebRTC Client issues a HTTP CONNECT request to the HTTP proxy
with the TCP address of a WebRTC peer in the Request URI. This is
used in the case of establishing ICE-TCP [RFC6544] with a WebRTC
Peer.
3. The Tunnel-Protocol HTTP Request Header Field
The client MAY include the Tunnel-Protocol Request Header field in a
HTTP Connect request to indicate the application layer protocol
within the tunnel.
3.1. Header Field Values
Valid values for the protocol field are taken from the registry
established in [I-D.ietf-tls-applayerprotoneg]. For the purposes of
WebRTC, the values "webrtc" [I-D.thomson-rtcweb-alpn] and "turn"
[I-D.patil-tram-alpn] are applicable.
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3.2. 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].
Tunnel-Protocol = "Tunnel-Protocol":" protocol | protocol-extension
protocol = "webrtc" | "turn"
protocol-extension = token
3.3. TURN as the Tunnel Protocol
The RTCWEB transports specification [I-D.ietf-rtcweb-transports]
requires that a WebRTC client support the modes of TURN that uses TCP
and TLS between the client and the TURN server in order to deal with
firewalls blocking UDP traffic. In the case where HTTP Connect is
used to establish a tunnel to the TURN server the client SHOULD
include the "Tunnel-Protocol" header field with the value "turn"
[I-D.patil-tram-alpn] as shown in the example below.
CONNECT turn_server.example.com:5349 HTTP/1.1
Host: turn_server.example.com:5349
Tunnel-Protocol: turn
3.4. ICE-TCP / WebRTC as the Tunnel Protocol
[I-D.ietf-rtcweb-transports] also requires that a WebRTC client
support ICE-TCP [RFC6544] as a mechanism to allow webrtc applications
to communicate to peers with public IP addresses across UDP-blocking
firewalls without using a TURN server. In this case the client
SHOULD include the "Tunnel-Protocol" header field with the value
"webrtc" [I-D.thomson-rtcweb-alpn] as shown in the example below.
CONNECT 198.51.100.0:8999 HTTP/1.1
Host: 198.51.100.0:8999
Tunnel-Protocol: webrtc
Note: The protocol "c_webrtc" described in [I-D.thomson-rtcweb-alpn]
is not relevent in this context and when used at the TLS layer the
client SHOULD use "webrtc" in the Tunnel-Protocol header. OPEN ISSUE
- Is this correct?
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4. IANA Considerations
To Be Added
5. Security Considerations
In case of using HTTP CONNECT to a TURN server the security
consideration of [RFC7231], Section-4.3.6] 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 and HTTP Proxies may of course not support the
header and therefore ignore it. If the header is not present or
ignored then the proxy has no explicit indication as to the purpose
of the tunnel on which to provide consent, this is the generic case
that exists without the Tunnel-Protocol header.
6. References
6.1. Normative References
[I-D.patil-tram-alpn]
Patil, P., Reddy, T., Salgueiro, G., and M. Petit-
Huguenin, "Application Layer Protocol Negotiation (ALPN)
for Session Traversal Utilities for NAT (STUN)", draft-
patil-tram-alpn-00 (work in progress), April 2014.
[I-D.thomson-rtcweb-alpn]
Thomson, M., "Application Layer Protocol Negotiation for
Web Real-Time Communications (WebRTC)", draft-thomson-
rtcweb-alpn-00 (work in progress), April 2014.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC7230] Fielding, R. and J. Reschke, "Hypertext Transfer Protocol
(HTTP/1.1): Message Syntax and Routing", RFC 7230, June
2014.
[RFC7231] Fielding, R. and J. Reschke, "Hypertext Transfer Protocol
(HTTP/1.1): Semantics and Content", RFC 7231, June 2014.
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6.2. Informative References
[I-D.ietf-rtcweb-transports]
Alvestrand, H., "Transports for RTCWEB", draft-ietf-
rtcweb-transports-05 (work in progress), June 2014.
[I-D.ietf-rtcweb-use-cases-and-requirements]
Holmberg, C., Hakansson, S., and G. Eriksson, "Web Real-
Time Communication Use-cases and Requirements", draft-
ietf-rtcweb-use-cases-and-requirements-14 (work in
progress), February 2014.
[I-D.ietf-tls-applayerprotoneg]
Friedl, S., Popov, A., Langley, A., and S. Emile,
"Transport Layer Security (TLS) Application Layer Protocol
Negotiation Extension", draft-ietf-tls-applayerprotoneg-05
(work in progress), March 2014.
[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.2", RFC 5246, August 2008.
[RFC6544] Rosenberg, J., Keranen, A., Lowekamp, B., and A. Roach,
"TCP Candidates with Interactive Connectivity
Establishment (ICE)", RFC 6544, March 2012.
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
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Martin Thomson
Mozilla
331 E Evelyn Street
Mountain View, CA 94041
US
Email: martin.thomson@gmail.com
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