draft-ietf-httpbis-h2-websockets-07.txt   rfc8441.txt 
HTTP P. McManus Internet Engineering Task Force (IETF) P. McManus
Internet-Draft Mozilla Request for Comments: 8441 Mozilla
Updates: 6455 (if approved) June 18, 2018 Updates: 6455 September 2018
Intended status: Standards Track Category: Standards Track
Expires: December 20, 2018 ISSN: 2070-1721
Bootstrapping WebSockets with HTTP/2 Bootstrapping WebSockets with HTTP/2
draft-ietf-httpbis-h2-websockets-07
Abstract Abstract
This document defines a mechanism for running the WebSocket Protocol This document defines a mechanism for running the WebSocket Protocol
(RFC 6455) over a single stream of an HTTP/2 connection. (RFC 6455) over a single stream of an HTTP/2 connection.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This is an Internet Standards Track document.
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 https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months This document is a product of the Internet Engineering Task Force
and may be updated, replaced, or obsoleted by other documents at any (IETF). It represents the consensus of the IETF community. It has
time. It is inappropriate to use Internet-Drafts as reference received public review and has been approved for publication by the
material or to cite them other than as "work in progress." Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 7841.
This Internet-Draft will expire on December 20, 2018. Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc8441.
Copyright Notice Copyright Notice
Copyright (c) 2018 IETF Trust and the persons identified as the Copyright (c) 2018 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
(https://trustee.ietf.org/license-info) in effect on the date of (https://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
skipping to change at page 2, line 11 skipping to change at page 2, line 11
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
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
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. The SETTINGS_ENABLE_CONNECT_PROTOCOL SETTINGS Parameter . . . 3 3. The SETTINGS_ENABLE_CONNECT_PROTOCOL SETTINGS Parameter . . . 3
4. The Extended CONNECT Method . . . . . . . . . . . . . . . . . 4 4. The Extended CONNECT Method . . . . . . . . . . . . . . . . . 4
5. Using Extended CONNECT To Bootstrap the WebSocket Protocol . 4 5. Using Extended CONNECT to Bootstrap the WebSocket Protocol . 4
5.1. Example . . . . . . . . . . . . . . . . . . . . . . . . . 5 5.1. Example . . . . . . . . . . . . . . . . . . . . . . . . . 6
6. Design Considerations . . . . . . . . . . . . . . . . . . . . 6 6. Design Considerations . . . . . . . . . . . . . . . . . . . . 6
7. About Intermediaries . . . . . . . . . . . . . . . . . . . . 6 7. About Intermediaries . . . . . . . . . . . . . . . . . . . . 6
8. Security Considerations . . . . . . . . . . . . . . . . . . . 7 8. Security Considerations . . . . . . . . . . . . . . . . . . . 7
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
10. Normative References . . . . . . . . . . . . . . . . . . . . 7 9.1. A New HTTP/2 Setting . . . . . . . . . . . . . . . . . . 7
9.2. A New HTTP Upgrade Token . . . . . . . . . . . . . . . . 7
10. Normative References . . . . . . . . . . . . . . . . . . . . 8
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 8 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 8
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 8 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction 1. Introduction
The Hypertext Transfer Protocol (HTTP) [RFC7230] provides compatible The Hypertext Transfer Protocol (HTTP) [RFC7230] provides compatible
resource-level semantics across different versions but it does not resource-level semantics across different versions, but it does not
offer compatibility at the connection management level. Other offer compatibility at the connection-management level. Other
protocols, such as WebSockets, that rely on connection management protocols that rely on connection-management details of HTTP, such as
details of HTTP must be updated for new versions of HTTP. WebSockets, must be updated for new versions of HTTP.
The WebSocket Protocol [RFC6455] uses the HTTP/1.1 Upgrade mechanism The WebSocket Protocol [RFC6455] uses the HTTP/1.1 Upgrade mechanism
(Section 6.7 of [RFC7230]) to transition a TCP connection from HTTP (Section 6.7 of [RFC7230]) to transition a TCP connection from HTTP
into a WebSocket connection. A different approach must be taken with into a WebSocket connection. A different approach must be taken with
HTTP/2 [RFC7540]. HTTP/2 does not allow connection-wide header HTTP/2 [RFC7540]. Due to its multiplexing nature, HTTP/2 does not
fields and status codes such as the Upgrade and Connection request allow connection-wide header fields or status codes, such as the
header fields or the 101 (Switching Protocols) response code due to Upgrade and Connection request-header fields or the 101 (Switching
its multiplexing nature. These are all required by the [RFC6455] Protocols) response code. These are all required by the [RFC6455]
opening handshake. opening handshake.
Being able to bootstrap WebSockets from HTTP/2 allows one TCP Being able to bootstrap WebSockets from HTTP/2 allows one TCP
connection to be shared by both protocols and extends HTTP/2's more connection to be shared by both protocols and extends HTTP/2's more
efficient use of the network to WebSockets. efficient use of the network to WebSockets.
This document extends the HTTP CONNECT method (as specified for This document extends the HTTP CONNECT method, as specified for
HTTP/2 in Section 8.3 of [RFC7540]). The extension allows the HTTP/2 in Section 8.3 of [RFC7540]. The extension allows the
substitution of a new protocol name to connect to rather than the substitution of a new protocol name to connect to rather than the
external host normally used by CONNECT. The result is a tunnel on a external host normally used by CONNECT. The result is a tunnel on a
single HTTP/2 stream that can carry data for WebSockets (or any other single HTTP/2 stream that can carry data for WebSockets (or any other
protocol). The other streams on the connection may carry more protocol). The other streams on the connection may carry more
extended CONNECT tunnels, traditional HTTP/2 data, or a mixture of extended CONNECT tunnels, traditional HTTP/2 data, or a mixture of
both. both.
This tunneled stream will be multiplexed with other regular streams This tunneled stream will be multiplexed with other regular streams
on the connection and enjoys the normal priority, cancellation, and on the connection and enjoys the normal priority, cancellation, and
flow control features of HTTP/2. flow-control features of HTTP/2.
Streams that successfully establish a WebSocket connection using a Streams that successfully establish a WebSocket connection using a
tunneled stream and the modifications to the opening handshake tunneled stream and the modifications to the opening handshake
defined in this document then use the traditional WebSocket Protocol, defined in this document then use the traditional WebSocket Protocol,
treating the stream as if were the TCP connection in that treating the stream as if it were the TCP connection in that
specification. specification.
2. Terminology 2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP "OPTIONAL" in this document are to be interpreted as described in
14 [RFC2119] [RFC8174] when, and only when, they appear in all BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
3. The SETTINGS_ENABLE_CONNECT_PROTOCOL SETTINGS Parameter 3. The SETTINGS_ENABLE_CONNECT_PROTOCOL SETTINGS Parameter
This document adds a new SETTINGS Parameter to those defined by This document adds a new SETTINGS parameter to those defined by
[RFC7540], Section 6.5.2. [RFC7540], Section 6.5.2.
The new parameter name is SETTINGS_ENABLE_CONNECT_PROTOCOL. The The new parameter name is SETTINGS_ENABLE_CONNECT_PROTOCOL. The
value of the parameter MUST be 0 or 1. value of the parameter MUST be 0 or 1.
Upon receipt of SETTINGS_ENABLE_CONNECT_PROTOCOL with a value of 1, a Upon receipt of SETTINGS_ENABLE_CONNECT_PROTOCOL with a value of 1, a
client MAY use the Extended CONNECT definition of this document when client MAY use the Extended CONNECT as defined in this document when
creating new streams. Receipt of this parameter by a server does not creating new streams. Receipt of this parameter by a server does not
have any impact. have any impact.
A sender MUST NOT send a SETTINGS_ENABLE_CONNECT_PROTOCOL parameter A sender MUST NOT send a SETTINGS_ENABLE_CONNECT_PROTOCOL parameter
with the value of 0 after previously sending a value of 1. with the value of 0 after previously sending a value of 1.
The use of a SETTINGS Parameter to opt-in to an otherwise Using a SETTINGS parameter to opt into an otherwise incompatible
incompatible protocol change is a use of "Extending HTTP/2" defined protocol change is a use of "Extending HTTP/2" defined by Section 5.5
by Section 5.5 of [RFC7540]. Specifically, the addition a new of [RFC7540]. Specifically, the addition a new pseudo-header field,
pseudo-header field ":protocol" and the change in meaning of the ":protocol", and the change in meaning of the :authority pseudo-
":authority" pseudo-header field in Section 4 require opt-in header field in Section 4 require opt-in negotiation. If a client
negotiation. If a client were to use the provisions of the extended were to use the provisions of the extended CONNECT method defined in
CONNECT method defined in this document without first receiving a this document without first receiving a
SETTINGS_ENABLE_CONNECT_PROTOCOL parameter, a non-supporting peer SETTINGS_ENABLE_CONNECT_PROTOCOL parameter, a non-supporting peer
would detect a malformed request and generate a stream error would detect a malformed request and generate a stream error
(Section 8.1.2.6 of [RFC7540]). (Section 8.1.2.6 of [RFC7540]).
4. The Extended CONNECT Method 4. The Extended CONNECT Method
Usage of the CONNECT method in HTTP/2 is defined by Section 8.3 of Usage of the CONNECT method in HTTP/2 is defined by Section 8.3 of
[RFC7540]. This extension modifies the method in the following ways: [RFC7540]. This extension modifies the method in the following ways:
o A new pseudo-header field :protocol MAY be included on request o A new pseudo-header field :protocol MAY be included on request
HEADERS indicating the desired protocol to be spoken on the tunnel HEADERS indicating the desired protocol to be spoken on the tunnel
created by CONNECT. The pseudo-header field is single valued and created by CONNECT. The pseudo-header field is single valued and
contains a value from the HTTP Upgrade Token Registry located at contains a value from the "Hypertext Transfer Protocol (HTTP)
https://www.iana.org/assignments/http-upgrade-tokens/http-upgrade- Upgrade Token Registry" located at
tokens.xhtml <https://www.iana.org/assignments/http-upgrade-tokens/>
o On requests that contain the :protocol pseudo-header field, the o On requests that contain the :protocol pseudo-header field, the
:scheme and :path pseudo-header fields of the target URI (See :scheme and :path pseudo-header fields of the target URI (see
Section 5) MUST also be included. Section 5) MUST also be included.
o On requests bearing the :protocol pseudo-header field, the o On requests bearing the :protocol pseudo-header field, the
:authority pseudo-header field is interpreted according to :authority pseudo-header field is interpreted according to
Section 8.1.2.3 of [RFC7540] instead of Section 8.3 of [RFC7540]. Section 8.1.2.3 of [RFC7540] instead of Section 8.3 of that
In particular, the server MUST NOT create a tunnel to the host document. In particular, the server MUST NOT create a tunnel to
indicated by the :authority as it would with a CONNECT method the host indicated by the :authority as it would with a CONNECT
request that was not modified by this extension. method request that was not modified by this extension.
Upon receiving a CONNECT request bearing the :protocol pseudo-header Upon receiving a CONNECT request bearing the :protocol pseudo-header
field the server establishes a tunnel to another service of the field, the server establishes a tunnel to another service of the
protocol type indicated by the pseudo-header field. This service may protocol type indicated by the pseudo-header field. This service may
or may not be co-located with the server. or may not be co-located with the server.
5. Using Extended CONNECT To Bootstrap the WebSocket Protocol 5. Using Extended CONNECT to Bootstrap the WebSocket Protocol
The :protocol pseudo-header field MUST be included in the CONNECT The :protocol pseudo-header field MUST be included in the CONNECT
request and it MUST have a value of "websocket" to initiate a request, and it MUST have a value of "websocket" to initiate a
WebSocket connection on an HTTP/2 stream. Other HTTP request and WebSocket connection on an HTTP/2 stream. Other HTTP request and
response header fields, such as those for manipulating cookies, may response-header fields, such as those for manipulating cookies, may
be included in the HEADERS with the CONNECT method as usual. This be included in the HEADERS with the CONNECT method as usual. This
request replaces the GET-based request in [RFC6455] and is used to request replaces the GET-based request in [RFC6455] and is used to
process the WebSockets opening handshake. process the WebSockets opening handshake.
The scheme of the target URI (Section 5.1 of [RFC7230]) MUST be The scheme of the target URI (Section 5.1 of [RFC7230]) MUST be
"https" for "wss" schemed WebSockets and "http" for "ws" schemed "https" for "wss"-schemed WebSockets and "http" for "ws"-schemed
WebSockets. The remainder of the Target URI is the same as the WebSockets. The remainder of the target URI is the same as the
websocket URI. The websocket URI is still used for proxy WebSocket URI. The WebSocket URI is still used for proxy
autoconfiguration. The security requirements for the HTTP/2 autoconfiguration. The security requirements for the HTTP/2
connection used by this specification are established by [RFC7540] connection used by this specification are established by [RFC7540]
for https requests and [RFC8164] for http requests. for https requests and [RFC8164] for http requests.
[RFC6455] requires the use of Connection and Upgrade header fields [RFC6455] requires the use of Connection and Upgrade header fields
that are not part of HTTP/2. They MUST NOT be included in the that are not part of HTTP/2. They MUST NOT be included in the
CONNECT request defined here. CONNECT request defined here.
[RFC6455] requires the use of a Host header field which is also not [RFC6455] requires the use of a Host header field that is also not
part of HTTP/2. The Host information is conveyed as part of the part of HTTP/2. The Host information is conveyed as part of the
:authority pseudo-header field which is required on every HTTP/2 :authority pseudo-header field, which is required on every HTTP/2
transaction. transaction.
Implementations using this extended CONNECT to bootstrap WebSockets Implementations using this extended CONNECT to bootstrap WebSockets
do not do the processing of the [RFC6455] Sec-WebSocket-Key and Sec- do not do the processing of the Sec-WebSocket-Key and Sec-WebSocket-
WebSocket-Accept header fields as that functionality has been Accept header fields of [RFC6455] as that functionality has been
superseded by the :protocol pseudo-header field. superseded by the :protocol pseudo-header field.
The Origin [RFC6454], Sec-WebSocket-Version, Sec-WebSocket-Protocol, The Origin [RFC6454], Sec-WebSocket-Version, Sec-WebSocket-Protocol,
and Sec-WebSocket-Extensions header fields are used in the CONNECT and Sec-WebSocket-Extensions header fields are used in the CONNECT
request and response header fields in the same way as defined in request and response-header fields as defined in [RFC6455]. Note
[RFC6455]. Note that HTTP/1 header field names were case-insensitive that HTTP/1 header field names were case insensitive, whereas HTTP/2
and HTTP/2 requires they be encoded as lower case. requires they be encoded as lowercase.
After successfully processing the opening handshake, the peers should After successfully processing the opening handshake, the peers should
proceed with the WebSocket Protocol [RFC6455] using the HTTP/2 stream proceed with the WebSocket Protocol [RFC6455] using the HTTP/2 stream
from the CONNECT transaction as if it were the TCP connection from the CONNECT transaction as if it were the TCP connection
referred to in [RFC6455]. The state of the WebSocket connection at referred to in [RFC6455]. The state of the WebSocket connection at
this point is OPEN as defined by [RFC6455], Section 4.1. this point is OPEN, as defined by [RFC6455], Section 4.1.
The HTTP/2 stream closure is also analogous to the TCP connection The HTTP/2 stream closure is also analogous to the TCP connection
closure of [RFC6455]. Orderly TCP level closures are represented as closure of [RFC6455]. Orderly TCP-level closures are represented as
END_STREAM ([RFC7540], Section 6.1) flags and RST exceptions are END_STREAM flags ([RFC7540], Section 6.1). RST exceptions are
represented with the RST_STREAM ([RFC7540], Section 6.4) frame with represented with the RST_STREAM frame ([RFC7540], Section 6.4) with
the CANCEL ([RFC7540], Section 7) error code. the CANCEL error code ([RFC7540], Section 7).
5.1. Example 5.1. Example
[[ From Client ]] [[ From Server ]] [[ From Client ]] [[ From Server ]]
SETTINGS SETTINGS
SETTINGS_ENABLE_CONNECT_[..] = 1 SETTINGS_ENABLE_CONNECT_[..] = 1
HEADERS + END_HEADERS HEADERS + END_HEADERS
:method = CONNECT :method = CONNECT
:protocol = websocket :protocol = websocket
:scheme = https :scheme = https
:path = /chat :path = /chat
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A more native integration with HTTP/2 is certainly possible with A more native integration with HTTP/2 is certainly possible with
larger additions to HTTP/2. This design was selected to minimize the larger additions to HTTP/2. This design was selected to minimize the
solution complexity while still addressing the primary concern of solution complexity while still addressing the primary concern of
running HTTP/2 and WebSockets concurrently. running HTTP/2 and WebSockets concurrently.
7. About Intermediaries 7. About Intermediaries
This document does not change how WebSockets interacts with HTTP This document does not change how WebSockets interacts with HTTP
forward proxies. If a client wishing to speak WebSockets connects forward proxies. If a client wishing to speak WebSockets connects
via HTTP/2 to an HTTP proxy it should continue to use a traditional via HTTP/2 to an HTTP proxy, it should continue to use a traditional
(i.e. not with a :protocol pseudo-header field) CONNECT to tunnel CONNECT (i.e., not with a :protocol pseudo-header field) to tunnel
through that proxy to the WebSocket server via HTTP. through that proxy to the WebSocket server via HTTP.
The resulting version of HTTP on that tunnel determines whether The resulting version of HTTP on that tunnel determines whether
WebSockets is initiated directly or via a modified CONNECT request WebSockets is initiated directly or via a modified CONNECT request
described in this document. described in this document.
8. Security Considerations 8. Security Considerations
[RFC6455] ensures that non-WebSockets clients, especially [RFC6455] ensures that non-WebSockets clients, especially
XMLHttpRequest based clients, cannot make a WebSocket connection. XMLHttpRequest-based clients, cannot make a WebSocket connection.
Its primary mechanism for doing that is the use of Sec- prefixed Its primary mechanism for doing that is the use of Sec-prefixed
request header fields that cannot be created by XMLHttpRequest-based request-header fields that cannot be created by XMLHttpRequest-based
clients. This specification addresses that concern in two ways: clients. This specification addresses that concern in two ways:
o XMLHttpRequest also prohibits use of the CONNECT method in o XMLHttpRequest also prohibits use of the CONNECT method in
addition to Sec- prefixed request header fields. addition to Sec-prefixed request-header fields.
o The use of a pseudo-header field is something that is connection o The use of a pseudo-header field is something that is connection
specific and HTTP/2 does not ever allow to be created outside of specific, and HTTP/2 never allows a pseudo-header to be created
the protocol stack. outside of the protocol stack.
The security considerations of [RFC6455] section 10 continue to apply The security considerations of [RFC6455], Section 10 continue to
to the use of the WebSocket Protocol when using this specification apply to the use of the WebSocket Protocol when using this
with the exception of 10.8. That section is not relevant because it specification, with the exception of 10.8. That section is not
is specific to the boostrapping handshake that is changed in this relevant, because it is specific to the bootstrapping handshake that
document. is changed in this document.
9. IANA Considerations 9. IANA Considerations
This document establishes an entry for the HTTP/2 Settings Registry 9.1. A New HTTP/2 Setting
This document registers an entry in the "HTTP/2 Settings" registry
that was established by Section 11.3 of [RFC7540]. that was established by Section 11.3 of [RFC7540].
Name: SETTINGS_ENABLE_CONNECT_PROTOCOL Code: 0x8
Name: SETTINGS_ENABLE_CONNECT_PROTOCOL
Initial Value: 0
Specification: This document
Code: 0x8 9.2. A New HTTP Upgrade Token
Initial Value: 0 This document registers an entry in the "HTTP Upgrade Tokens"
registry that was established by [RFC7230].
Specification: This document Value: websocket
Description: The Web Socket Protocol
Expected Version Tokens:
References: [RFC6455] [RFC8441]
10. Normative References 10. 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, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC6454] Barth, A., "The Web Origin Concept", RFC 6454, [RFC6454] Barth, A., "The Web Origin Concept", RFC 6454,
DOI 10.17487/RFC6454, December 2011, DOI 10.17487/RFC6454, December 2011,
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