draft-ietf-hybi-thewebsocketprotocol-07.txt   draft-ietf-hybi-thewebsocketprotocol-08.txt 
HyBi Working Group I. Fette HyBi Working Group I. Fette
Internet-Draft Google, Inc. Internet-Draft Google, Inc.
Intended status: Standards Track April 22, 2011 Intended status: Standards Track June 7, 2011
Expires: October 24, 2011 Expires: December 9, 2011
The WebSocket protocol The WebSocket protocol
draft-ietf-hybi-thewebsocketprotocol-07 draft-ietf-hybi-thewebsocketprotocol-08
Abstract Abstract
The WebSocket protocol enables two-way communication between a user The WebSocket protocol enables two-way communication between a client
agent running untrusted code running in a controlled environment to a running untrusted code running in a controlled environment to a
remote host that has opted-in to communications from that code. The remote host that has opted-in to communications from that code. The
security model used for this is the Origin-based security model security model used for this is the Origin-based security model
commonly used by Web browsers. The protocol consists of an initial commonly used by Web browsers. The protocol consists of an opening
handshake followed by basic message framing, layered over TCP. The handshake followed by basic message framing, layered over TCP. (In
goal of this technology is to provide a mechanism for browser-based theory, any transport protocol could be used so long as it provides
applications that need two-way communication with servers that does for reliable transport, is byte clean, and supports relatively large
not rely on opening multiple HTTP connections (e.g. using message sizes. However, for this document, we consider only TCP.)
The goal of this technology is to provide a mechanism for browser-
based applications that need two-way communication with servers that
does not rely on opening multiple HTTP connections (e.g. using
XMLHttpRequest or <iframe>s and long polling). XMLHttpRequest or <iframe>s and long polling).
Please send feedback to the hybi@ietf.org mailing list. Please send feedback to the hybi@ietf.org mailing list.
Status of this Memo Status of this Memo
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provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on October 24, 2011. This Internet-Draft will expire on December 9, 2011.
Copyright Notice Copyright Notice
Copyright (c) 2011 IETF Trust and the persons identified as the Copyright (c) 2011 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Background . . . . . . . . . . . . . . . . . . . . . . . . 4 1.1. Background . . . . . . . . . . . . . . . . . . . . . . . 4
1.2. Protocol overview . . . . . . . . . . . . . . . . . . . . 4 1.2. Protocol Overview . . . . . . . . . . . . . . . . . . . . 4
1.3. Opening handshake . . . . . . . . . . . . . . . . . . . . 6 1.3. Opening Handshake . . . . . . . . . . . . . . . . . . . . 6
1.4. Closing handshake . . . . . . . . . . . . . . . . . . . . 8 1.4. Closing Handshake . . . . . . . . . . . . . . . . . . . . 9
1.5. Design philosophy . . . . . . . . . . . . . . . . . . . . 9 1.5. Design Philosophy . . . . . . . . . . . . . . . . . . . . 9
1.6. Security model . . . . . . . . . . . . . . . . . . . . . . 10 1.6. Security Model . . . . . . . . . . . . . . . . . . . . . 10
1.7. Relationship to TCP and HTTP . . . . . . . . . . . . . . . 10 1.7. Relationship to TCP and HTTP . . . . . . . . . . . . . . 11
1.8. Establishing a connection . . . . . . . . . . . . . . . . 11 1.8. Establishing a Connection . . . . . . . . . . . . . . . . 11
1.9. Subprotocols using the WebSocket protocol . . . . . . . . 11 1.9. Subprotocols Using the WebSocket protocol . . . . . . . . 11
2. Conformance requirements . . . . . . . . . . . . . . . . . . . 13 2. Conformance Requirements . . . . . . . . . . . . . . . . . . . 13
2.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 13 2.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 13
3. WebSocket URIs . . . . . . . . . . . . . . . . . . . . . . . . 15 3. WebSocket URIs . . . . . . . . . . . . . . . . . . . . . . . . 15
3.1. Parsing WebSocket URIs . . . . . . . . . . . . . . . . . . 15 4. Data Framing . . . . . . . . . . . . . . . . . . . . . . . . . 16
3.2. Constructing WebSocket URIs . . . . . . . . . . . . . . . 16 4.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . 16
3.3. Valid WebSocket URIs . . . . . . . . . . . . . . . . . . . 16 4.2. Base Framing Protocol . . . . . . . . . . . . . . . . . . 16
4. Data Framing . . . . . . . . . . . . . . . . . . . . . . . . . 17 4.3. Client-to-Server Masking . . . . . . . . . . . . . . . . 20
4.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . 17 4.4. Fragmentation . . . . . . . . . . . . . . . . . . . . . . 21
4.2. Base Framing Protocol . . . . . . . . . . . . . . . . . . 17 4.5. Control Frames . . . . . . . . . . . . . . . . . . . . . 22
4.3. Client-to-Server Masking . . . . . . . . . . . . . . . . . 20
4.4. Fragmentation . . . . . . . . . . . . . . . . . . . . . . 21
4.5. Control Frames . . . . . . . . . . . . . . . . . . . . . . 23
4.5.1. Close . . . . . . . . . . . . . . . . . . . . . . . . 23 4.5.1. Close . . . . . . . . . . . . . . . . . . . . . . . . 23
4.5.2. Ping . . . . . . . . . . . . . . . . . . . . . . . . . 24 4.5.2. Ping . . . . . . . . . . . . . . . . . . . . . . . . . 23
4.5.3. Pong . . . . . . . . . . . . . . . . . . . . . . . . . 24 4.5.3. Pong . . . . . . . . . . . . . . . . . . . . . . . . . 24
4.6. Data Frames . . . . . . . . . . . . . . . . . . . . . . . 24 4.6. Data Frames . . . . . . . . . . . . . . . . . . . . . . . 24
4.7. Examples . . . . . . . . . . . . . . . . . . . . . . . . . 25 4.7. Examples . . . . . . . . . . . . . . . . . . . . . . . . 25
4.8. Extensibility . . . . . . . . . . . . . . . . . . . . . . 25 4.8. Extensibility . . . . . . . . . . . . . . . . . . . . . . 25
5. Opening Handshake . . . . . . . . . . . . . . . . . . . . . . 27 5. Opening Handshake . . . . . . . . . . . . . . . . . . . . . . 27
5.1. Client Requirements . . . . . . . . . . . . . . . . . . . 27 5.1. Client Requirements . . . . . . . . . . . . . . . . . . . 27
5.2. Server-side requirements . . . . . . . . . . . . . . . . . 31 5.2. Server-side Requirements . . . . . . . . . . . . . . . . 32
5.2.1. Reading the client's opening handshake . . . . . . . . 32 5.2.1. Reading the Client's Opening Handshake . . . . . . . . 32
5.2.2. Sending the server's opening handshake . . . . . . . . 32 5.2.2. Sending the Server's Opening Handshake . . . . . . . . 33
6. Error Handling . . . . . . . . . . . . . . . . . . . . . . . . 36 6. Sending and Receiving Data . . . . . . . . . . . . . . . . . . 37
6.1. Handling errors in UTF-8 from the server . . . . . . . . . 36 6.1. Sending Data . . . . . . . . . . . . . . . . . . . . . . 37
6.2. Handling errors in UTF-8 from the client . . . . . . . . . 36 6.2. Receiving Data . . . . . . . . . . . . . . . . . . . . . 37
7. Closing the connection . . . . . . . . . . . . . . . . . . . . 37 7. Closing the connection . . . . . . . . . . . . . . . . . . . . 39
7.1. Definitions . . . . . . . . . . . . . . . . . . . . . . . 37 7.1. Definitions . . . . . . . . . . . . . . . . . . . . . . . 39
7.1.1. Close the WebSocket Connection . . . . . . . . . . . . 37 7.1.1. Close the WebSocket Connection . . . . . . . . . . . . 39
7.1.2. Start the WebSocket Closing Handshake . . . . . . . . 37 7.1.2. Start the WebSocket Closing Handshake . . . . . . . . 39
7.1.3. The WebSocket Connection Is Closed . . . . . . . . . . 37 7.1.3. The WebSocket Closing Handshake is Started . . . . . . 39
7.1.4. Fail the WebSocket Connection . . . . . . . . . . . . 37 7.1.4. The WebSocket Connection is Closed . . . . . . . . . . 40
7.2. Abnormal closures . . . . . . . . . . . . . . . . . . . . 37 7.1.5. The WebSocket Connection Close Code . . . . . . . . . 40
7.2.1. Client-initiated closure . . . . . . . . . . . . . . . 38 7.1.6. The WebSocket Connection Close Reason . . . . . . . . 40
7.2.2. Server-initiated closure . . . . . . . . . . . . . . . 38 7.1.7. Fail the WebSocket Connection . . . . . . . . . . . . 41
7.3. Normal closure of connections . . . . . . . . . . . . . . 38 7.2. Abnormal Closures . . . . . . . . . . . . . . . . . . . . 41
7.4. Status codes . . . . . . . . . . . . . . . . . . . . . . . 38 7.2.1. Client-Initiated Closure . . . . . . . . . . . . . . . 41
7.4.1. Defined Status Codes . . . . . . . . . . . . . . . . . 38 7.2.2. Server-initiated closure . . . . . . . . . . . . . . . 42
7.4.2. Reserved status code ranges . . . . . . . . . . . . . 39 7.3. Normal Closure of Connections . . . . . . . . . . . . . . 42
8. Extensions . . . . . . . . . . . . . . . . . . . . . . . . . . 41 7.4. Status Codes . . . . . . . . . . . . . . . . . . . . . . 42
8.1. Negotiating extensions . . . . . . . . . . . . . . . . . . 41 7.4.1. Defined Status Codes . . . . . . . . . . . . . . . . . 42
8.2. Known extensions . . . . . . . . . . . . . . . . . . . . . 42 7.4.2. Reserved Status Code Ranges . . . . . . . . . . . . . 43
8.2.1. Compression . . . . . . . . . . . . . . . . . . . . . 42 8. Error Handling . . . . . . . . . . . . . . . . . . . . . . . . 45
9. Security considerations . . . . . . . . . . . . . . . . . . . 44 8.1. Handling Errors in UTF-8 from the Server . . . . . . . . 45
10. IANA considerations . . . . . . . . . . . . . . . . . . . . . 46 8.2. Handling Errors in UTF-8 from the Client . . . . . . . . 45
10.1. Registration of ws: scheme . . . . . . . . . . . . . . . . 46 9. Extensions . . . . . . . . . . . . . . . . . . . . . . . . . . 46
10.2. Registration of wss: scheme . . . . . . . . . . . . . . . 47 9.1. Negotiating Extensions . . . . . . . . . . . . . . . . . 46
10.3. Registration of the "WebSocket" HTTP Upgrade keyword . . . 48 9.2. Known Extensions . . . . . . . . . . . . . . . . . . . . 47
10.4. Sec-WebSocket-Key . . . . . . . . . . . . . . . . . . . . 48 9.2.1. Compression . . . . . . . . . . . . . . . . . . . . . 47
10.5. Sec-WebSocket-Extensions . . . . . . . . . . . . . . . . . 49 10. Security Considerations . . . . . . . . . . . . . . . . . . . 49
10.6. Sec-WebSocket-Accept . . . . . . . . . . . . . . . . . . . 50 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 51
10.7. Sec-WebSocket-Origin . . . . . . . . . . . . . . . . . . . 50 11.1. Registration of "ws:" Scheme . . . . . . . . . . . . . . 51
10.8. Sec-WebSocket-Protocol . . . . . . . . . . . . . . . . . . 51 11.2. Registration of "wss:" Scheme . . . . . . . . . . . . . . 52
10.9. Sec-WebSocket-Version . . . . . . . . . . . . . . . . . . 51 11.3. Registration of the "WebSocket" HTTP Upgrade Keyword . . 53
11. Using the WebSocket protocol from other specifications . . . . 53 11.4. Sec-WebSocket-Key . . . . . . . . . . . . . . . . . . . . 53
12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 54 11.5. Sec-WebSocket-Extensions . . . . . . . . . . . . . . . . 54
13. References . . . . . . . . . . . . . . . . . . . . . . . . . . 55 11.6. WebSocket Extension Name Registry . . . . . . . . . . . . 55
13.1. Normative References . . . . . . . . . . . . . . . . . . . 55 11.7. Sec-WebSocket-Accept . . . . . . . . . . . . . . . . . . 56
13.2. Informative References . . . . . . . . . . . . . . . . . . 56 11.8. Sec-WebSocket-Origin . . . . . . . . . . . . . . . . . . 56
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 57 11.9. Sec-WebSocket-Protocol . . . . . . . . . . . . . . . . . 57
11.10. WebSocket Subprotocol Name Registry . . . . . . . . . . . 57
11.11. Sec-WebSocket-Version . . . . . . . . . . . . . . . . . . 58
11.12. WebSocket Version Number Registry . . . . . . . . . . . . 59
11.13. WebSocket Close Code Number Registry . . . . . . . . . . 60
11.14. WebSocket Opcode Registry . . . . . . . . . . . . . . . . 61
11.15. WebSocket Framing Header Bits Registry . . . . . . . . . 62
12. Using the WebSocket protocol from Other Specifications . . . . 63
13. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 64
14. References . . . . . . . . . . . . . . . . . . . . . . . . . . 65
14.1. Normative References . . . . . . . . . . . . . . . . . . 65
14.2. Informative References . . . . . . . . . . . . . . . . . 66
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 68
1. Introduction 1. Introduction
1.1. Background 1.1. Background
_This section is non-normative._ _This section is non-normative._
Historically, creating an instant messenger chat client as a Web Historically, creating an instant messenger chat client as a Web
application has required an abuse of HTTP to poll the server for application has required an abuse of HTTP to poll the server for
updates while sending upstream notifications as distinct HTTP updates while sending upstream notifications as distinct HTTP
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traffic in both directions. This is what the WebSocket protocol traffic in both directions. This is what the WebSocket protocol
provides. Combined with the WebSocket API, it provides an provides. Combined with the WebSocket API, it provides an
alternative to HTTP polling for two-way communication from a Web page alternative to HTTP polling for two-way communication from a Web page
to a remote server. [WSAPI] to a remote server. [WSAPI]
The same technique can be used for a variety of Web applications: The same technique can be used for a variety of Web applications:
games, stock tickers, multiuser applications with simultaneous games, stock tickers, multiuser applications with simultaneous
editing, user interfaces exposing server-side services in real time, editing, user interfaces exposing server-side services in real time,
etc. etc.
1.2. Protocol overview 1.2. Protocol Overview
_This section is non-normative._ _This section is non-normative._
The protocol has two parts: a handshake, and then the data transfer. The protocol has two parts: a handshake, and then the data transfer.
The handshake from the client looks as follows: The handshake from the client looks as follows:
GET /chat HTTP/1.1 GET /chat HTTP/1.1
Host: server.example.com Host: server.example.com
Upgrade: websocket Upgrade: websocket
Connection: Upgrade Connection: Upgrade
Sec-WebSocket-Key: dGhlIHNhbXBsZSBub25jZQ== Sec-WebSocket-Key: dGhlIHNhbXBsZSBub25jZQ==
Sec-WebSocket-Origin: http://example.com Sec-WebSocket-Origin: http://example.com
Sec-WebSocket-Protocol: chat, superchat Sec-WebSocket-Protocol: chat, superchat
Sec-WebSocket-Version: 7 Sec-WebSocket-Version: 8
The handshake from the server looks as follows: The handshake from the server looks as follows:
HTTP/1.1 101 Switching Protocols HTTP/1.1 101 Switching Protocols
Upgrade: websocket Upgrade: websocket
Connection: Upgrade Connection: Upgrade
Sec-WebSocket-Accept: s3pPLMBiTxaQ9kYGzzhZRbK+xOo= Sec-WebSocket-Accept: s3pPLMBiTxaQ9kYGzzhZRbK+xOo=
Sec-WebSocket-Protocol: chat Sec-WebSocket-Protocol: chat
The leading line from the client follows the Request-Line format. The leading line from the client follows the Request-Line format.
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Once the client and server have both sent their handshakes, and if Once the client and server have both sent their handshakes, and if
the handshake was successful, then the data transfer part starts. the handshake was successful, then the data transfer part starts.
This is a two-way communication channel where each side can, This is a two-way communication channel where each side can,
independently from the other, send data at will. independently from the other, send data at will.
Clients and servers, after a successful handshake, transfer data back Clients and servers, after a successful handshake, transfer data back
and forth in conceptual units referred to in this specification as and forth in conceptual units referred to in this specification as
"messages". A message is a complete unit of data at an application "messages". A message is a complete unit of data at an application
level, with the expectation that many or most applications level, with the expectation that many or most applications
implementing this protocol (such as web user agents) provide APIs in implementing this protocol (such as web user agents) provide APIs in
terms of sending and receiving messages. The websocket message does terms of sending and receiving messages. The WebSocket message does
not necessarily correspond to a particular network layer framing, as not necessarily correspond to a particular network layer framing, as
a fragmented message may be coalesced, or vice versa, e.g. by an a fragmented message may be coalesced, or vice versa, e.g. by an
intermediary. intermediary.
Data is sent on the wire in the form of frames that have an Data is sent on the wire in the form of frames that have an
associated type. A message is composed of one or more frames, all of associated type. A message is composed of one or more frames, all of
which contain the same type of data. Broadly speaking, there are which contain the same type of data. Broadly speaking, there are
types for textual data, which is interpreted as UTF-8 [RFC3629] text, types for textual data, which is interpreted as UTF-8 [RFC3629] text,
binary data (whose interpretation is left up to the application), and binary data (whose interpretation is left up to the application), and
control frames, which are not intended to carry data for the control frames, which are not intended to carry data for the
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signal that the connection should be closed. This version of the signal that the connection should be closed. This version of the
protocol defines six frame types and leaves ten reserved for future protocol defines six frame types and leaves ten reserved for future
use. use.
The WebSocket protocol uses this framing so that specifications that The WebSocket protocol uses this framing so that specifications that
use the WebSocket protocol can expose such connections using an use the WebSocket protocol can expose such connections using an
event-based mechanism instead of requiring users of those event-based mechanism instead of requiring users of those
specifications to implement buffering and piecing together of specifications to implement buffering and piecing together of
messages manually. messages manually.
1.3. Opening handshake 1.3. Opening Handshake
_This section is non-normative._ _This section is non-normative._
The opening handshake is intended to be compatible with HTTP-based The opening handshake is intended to be compatible with HTTP-based
server-side software and intermediaries, so that a single port can be server-side software and intermediaries, so that a single port can be
used by both HTTP clients talking to that server and WebSocket used by both HTTP clients talking to that server and WebSocket
clients talking to that server. To this end, the WebSocket client's clients talking to that server. To this end, the WebSocket client's
handshake is an HTTP Upgrade request: handshake is an HTTP Upgrade request:
GET /chat HTTP/1.1 GET /chat HTTP/1.1
Host: server.example.com Host: server.example.com
Upgrade: websocket Upgrade: websocket
Connection: Upgrade Connection: Upgrade
Sec-WebSocket-Key: dGhlIHNhbXBsZSBub25jZQ== Sec-WebSocket-Key: dGhlIHNhbXBsZSBub25jZQ==
Sec-WebSocket-Origin: http://example.com Sec-WebSocket-Origin: http://example.com
Sec-WebSocket-Protocol: chat, superchat Sec-WebSocket-Protocol: chat, superchat
Sec-WebSocket-Version: 7 Sec-WebSocket-Version: 8
Headers in the handshake are sent by the client in a random order; Headers in the handshake are sent by the client in a random order;
the order is not meaningful. the order is not meaningful.
The "Request-URI" of the GET method [RFC2616] is used to identify the The "Request-URI" of the GET method [RFC2616] is used to identify the
endpoint of the WebSocket connection, both to allow multiple domains endpoint of the WebSocket connection, both to allow multiple domains
to be served from one IP address and to allow multiple WebSocket to be served from one IP address and to allow multiple WebSocket
endpoints to be served by a single server. endpoints to be served by a single server.
The client includes the hostname in the Host header of its handshake The client includes the hostname in the Host header of its handshake
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the WebSocket protocol) are acceptable to the client. The server the WebSocket protocol) are acceptable to the client. The server
selects one of the acceptable protocols and echoes that value in its selects one of the acceptable protocols and echoes that value in its
handshake to indicate that it has selected that protocol. handshake to indicate that it has selected that protocol.
Sec-WebSocket-Protocol: chat Sec-WebSocket-Protocol: chat
The |Sec-WebSocket-Origin| header is used to protect against The |Sec-WebSocket-Origin| header is used to protect against
unauthorized cross-origin use of a WebSocket server by scripts using unauthorized cross-origin use of a WebSocket server by scripts using
the |WebSocket| API in a Web browser. The server is informed of the the |WebSocket| API in a Web browser. The server is informed of the
script origin generating the WebSocket connection request. If the script origin generating the WebSocket connection request. If the
server does not wish to accept connections from this origin, it can server does not wish to accept connections from this origin, it can
choose to abort the connection. This header is sent by browser choose to reject the connection by sending an appropriate HTTP error
clients, for non-browser clients this header may be sent if it makes code. This header is sent by browser clients, for non-browser
sense in the context of those clients. clients this header may be sent if it makes sense in the context of
those clients.
NOTE: It is worth noting that for the attack cases this header
protects against, the untrusted party is typically the author of a
JavaScript application that is executing in the context of the
client. The client itself can contact the server and via the
mechanism of the |Sec-WebSocket-Origin| header, determine whether to
extend those communication privileges to the JavaScript application.
A JavaScript application cannot set a header starting with "Sec-" via
XHR. The intent is not to prevent non-browsers from establishing
connections, but rather to ensure that browsers under the control of
potentially malicious JavaScript cannot fake a WebSocket handshake.
Finally, the server has to prove to the client that it received the Finally, the server has to prove to the client that it received the
client's WebSocket handshake, so that the server doesn't accept client's WebSocket handshake, so that the server doesn't accept
connections that are not WebSocket connections. This prevents an connections that are not WebSocket connections. This prevents an
attacker from tricking a WebSocket server by sending it carefully- attacker from tricking a WebSocket server by sending it carefully-
crafted packets using |XMLHttpRequest| or a |form| submission. crafted packets using |XMLHttpRequest| or a |form| submission.
To prove that the handshake was received, the server has to take two To prove that the handshake was received, the server has to take two
pieces of information and combine them to form a response. The first pieces of information and combine them to form a response. The first
piece of information comes from the |Sec-WebSocket-Key| header in the piece of information comes from the |Sec-WebSocket-Key| header in the
client handshake: client handshake:
Sec-WebSocket-Key: dGhlIHNhbXBsZSBub25jZQ== Sec-WebSocket-Key: dGhlIHNhbXBsZSBub25jZQ==
For this header, the server has to take the value (as present in the For this header, the server has to take the value (as present in the
header, e.g. the base64-encoded [RFC4648] version minus leading and header, e.g. the base64-encoded [RFC4648] version minus leading and
trailing whitespace), and concatenate this with the GUID "258EAFA5- trailing whitespace), and concatenate this with the GUID "258EAFA5-
E914-47DA-95CA-C5AB0DC85B11" in string form, which is unlikely to be E914-47DA-95CA-C5AB0DC85B11" in string form, which is unlikely to be
used by network endpoints that do not understand the WebSocket used by network endpoints that do not understand the WebSocket
protocol. A SHA-1 hash, base64-encoded, of this concatenation is protocol. A SHA-1 hash (160 bits), base64-encoded, of this
then returned in the server's handshake [FIPS.180-2.2002]. concatenation is then returned in the server's handshake
[FIPS.180-2.2002].
Concretely, if as in the example above, header |Sec-WebSocket-Key| Concretely, if as in the example above, header |Sec-WebSocket-Key|
had the value "dGhlIHNhbXBsZSBub25jZQ==", the server would had the value "dGhlIHNhbXBsZSBub25jZQ==", the server would
concatenate the string "258EAFA5-E914-47DA-95CA-C5AB0DC85B11" to form concatenate the string "258EAFA5-E914-47DA-95CA-C5AB0DC85B11" to form
the string "dGhlIHNhbXBsZSBub25jZQ==258EAFA5-E914-47DA-95CA- the string "dGhlIHNhbXBsZSBub25jZQ==258EAFA5-E914-47DA-95CA-
C5AB0DC85B11". The server would then take the SHA-1 hash of this, C5AB0DC85B11". The server would then take the SHA-1 hash of this,
giving the value 0xb3 0x7a 0x4f 0x2c 0xc0 0x62 0x4f 0x16 0x90 0xf6 giving the value 0xb3 0x7a 0x4f 0x2c 0xc0 0x62 0x4f 0x16 0x90 0xf6
0x46 0x06 0xcf 0x38 0x59 0x45 0xb2 0xbe 0xc4 0xea. This value is 0x46 0x06 0xcf 0x38 0x59 0x45 0xb2 0xbe 0xc4 0xea. This value is
then base64-encoded, to give the value "s3pPLMBiTxaQ9kYGzzhZRbK+ then base64-encoded, to give the value "s3pPLMBiTxaQ9kYGzzhZRbK+
xOo=". This value would then be echoed in the header |Sec-WebSocket- xOo=". This value would then be echoed in the header |Sec-WebSocket-
skipping to change at page 8, line 31 skipping to change at page 8, line 44
HTTP/1.1 101 Switching Protocols HTTP/1.1 101 Switching Protocols
Upgrade: websocket Upgrade: websocket
Connection: Upgrade Connection: Upgrade
Sec-WebSocket-Accept: s3pPLMBiTxaQ9kYGzzhZRbK+xOo= Sec-WebSocket-Accept: s3pPLMBiTxaQ9kYGzzhZRbK+xOo=
These fields are checked by the Web browser when it is acting as a These fields are checked by the Web browser when it is acting as a
|WebSocket| client for scripted pages. If the |Sec-WebSocket-Accept| |WebSocket| client for scripted pages. If the |Sec-WebSocket-Accept|
value does not match the expected value, or if the header is missing, value does not match the expected value, or if the header is missing,
or if the HTTP status code is not 101, the connection will not be or if the HTTP status code is not 101, the connection will not be
established and WebSockets frames will not be sent. established and WebSocket frames will not be sent.
Option fields can also be included. In this version of the protocol, Option fields can also be included. In this version of the protocol,
the main option field is |Sec-WebSocket-Protocol|, which indicates the main option field is |Sec-WebSocket-Protocol|, which indicates
the subprotocol that the server has selected. Web browsers verify the subprotocol that the server has selected. Web browsers verify
that the server included one of the values as was specified in the that the server included one of the values as was specified in the
WebSocket client' handshake. A server that speaks multiple WebSocket client's handshake. A server that speaks multiple
subprotocols has to make sure it selects one based on the client's subprotocols has to make sure it selects one based on the client's
handshake and specifies it in its handshake. handshake and specifies it in its handshake.
Sec-WebSocket-Protocol: chat Sec-WebSocket-Protocol: chat
The server can also set cookie-related option fields to _set_ The server can also set cookie-related option fields to _set_
cookies, as in HTTP. cookies, as in HTTP.
1.4. Closing handshake 1.4. Closing Handshake
_This section is non-normative._ _This section is non-normative._
The closing handshake is far simpler than the opening handshake. The closing handshake is far simpler than the opening handshake.
Either peer can send a control frame with data containing a specified Either peer can send a control frame with data containing a specified
control sequence to begin the closing handshake (detailed in control sequence to begin the closing handshake (detailed in
Section 4.5.1). Upon receiving such a frame, the other peer sends a Section 4.5.1). Upon receiving such a frame, the other peer sends a
close frame in response, if it hasn't already sent one. Upon close frame in response, if it hasn't already sent one. Upon
receiving _that_ control frame, the first peer then closes the receiving _that_ control frame, the first peer then closes the
connection, safe in the knowledge that no further data is connection, safe in the knowledge that no further data is
forthcoming. forthcoming.
After sending a control frame indicating the connection should be After sending a control frame indicating the connection should be
closed, a peer does not send any further data; after receiving a closed, a peer does not send any further data; after receiving a
control frame indicating the connection should be closed, a peer control frame indicating the connection should be closed, a peer
discards any further data received. discards any further data received.
It is safe for both peers to initiate this handshake simultaneously. It is safe for both peers to initiate this handshake simultaneously.
The closing handshake is intended to replace the TCP closing The closing handshake is intended to complement the TCP closing
handshake (FIN/ACK), on the basis that the TCP closing handshake is handshake (FIN/ACK), on the basis that the TCP closing handshake is
not always reliable end-to-end, especially in the presence of man-in- not always reliable end-to-end, especially in the presence of man-in-
the-middle proxies and other intermediaries. the-middle proxies and other intermediaries.
By sending a close frame and waiting for a close frame in response, By sending a close frame and waiting for a close frame in response,
certain cases are avoided where data may be unnecessarily lost. For certain cases are avoided where data may be unnecessarily lost. For
instance, on some platforms, if a socket is closed with data in the instance, on some platforms, if a socket is closed with data in the
receive queue, a RST packet is sent, which will then cause recv() to receive queue, a RST packet is sent, which will then cause recv() to
fail for the party that received the RST, even if there was data fail for the party that received the RST, even if there was data
waiting to be read. waiting to be read.
1.5. Design philosophy 1.5. Design Philosophy
_This section is non-normative._ _This section is non-normative._
The WebSocket protocol is designed on the principle that there should The WebSocket protocol is designed on the principle that there should
be minimal framing (the only framing that exists is to make the be minimal framing (the only framing that exists is to make the
protocol frame-based instead of stream-based, and to support a protocol frame-based instead of stream-based, and to support a
distinction between Unicode text and binary frames). It is expected distinction between Unicode text and binary frames). It is expected
that metadata would be layered on top of WebSocket by the application that metadata would be layered on top of WebSocket by the application
layer, in the same way that metadata is layered on top of TCP by the layer, in the same way that metadata is layered on top of TCP by the
application layer (HTTP). application layer (HTTP).
Conceptually, WebSocket is really just a layer on top of TCP that Conceptually, WebSocket is really just a layer on top of TCP that
adds a Web "origin"-based security model for browsers; adds an adds a Web "origin"-based security model for browsers; adds an
addressing and protocol naming mechanism to support multiple services addressing and protocol naming mechanism to support multiple services
on one port and multiple host names on one IP address; layers a on one port and multiple host names on one IP address; layers a
framing mechanism on top of TCP to get back to the IP packet framing mechanism on top of TCP to get back to the IP packet
mechanism that TCP is built on, but without length limits; and re- mechanism that TCP is built on, but without length limits; and
implements the closing handshake in-band. Other than that, it adds includes an additional closing handshake in-band that is designed to
nothing. Basically it is intended to be as close to just exposing work in the presence of proxies and other intermediaries. Other than
raw TCP to script as possible given the constraints of the Web. It's that, it adds nothing. Basically it is intended to be as close to
also designed in such a way that its servers can share a port with just exposing raw TCP to script as possible given the constraints of
HTTP servers, by having its handshake be a valid HTTP Upgrade request the Web. It's also designed in such a way that its servers can share
mechanism also. a port with HTTP servers, by having its handshake be a valid HTTP
Upgrade request mechanism also.
The protocol is intended to be extensible; future versions will The protocol is intended to be extensible; future versions will
likely introduce additional concepts such as multiplexing. likely introduce additional concepts such as multiplexing.
1.6. Security model 1.6. Security Model
_This section is non-normative._ _This section is non-normative._
The WebSocket protocol uses the origin model used by Web browsers to The WebSocket protocol uses the origin model used by Web browsers to
restrict which Web pages can contact a WebSocket server when the restrict which Web pages can contact a WebSocket server when the
WebSocket protocol is used from a Web page. Naturally, when the WebSocket protocol is used from a Web page. Naturally, when the
WebSocket protocol is used by a dedicated client directly (i.e. not WebSocket protocol is used by a dedicated client directly (i.e. not
from a Web page through a Web browser), the origin model is not from a Web page through a Web browser), the origin model is not
useful, as the client can provide any arbitrary origin string. useful, as the client can provide any arbitrary origin string.
skipping to change at page 11, line 5 skipping to change at page 11, line 20
_This section is non-normative._ _This section is non-normative._
The WebSocket protocol is an independent TCP-based protocol. Its The WebSocket protocol is an independent TCP-based protocol. Its
only relationship to HTTP is that its handshake is interpreted by only relationship to HTTP is that its handshake is interpreted by
HTTP servers as an Upgrade request. HTTP servers as an Upgrade request.
By default the WebSocket protocol uses port 80 for regular WebSocket By default the WebSocket protocol uses port 80 for regular WebSocket
connections and port 443 for WebSocket connections tunneled over TLS connections and port 443 for WebSocket connections tunneled over TLS
[RFC2818]. [RFC2818].
1.8. Establishing a connection 1.8. Establishing a Connection
_This section is non-normative._ _This section is non-normative._
When a connection is to be made to a port that is shared by an HTTP When a connection is to be made to a port that is shared by an HTTP
server (a situation that is quite likely to occur with traffic to server (a situation that is quite likely to occur with traffic to
ports 80 and 443), the connection will appear to the HTTP server to ports 80 and 443), the connection will appear to the HTTP server to
be a regular GET request with an Upgrade offer. In relatively simple be a regular GET request with an Upgrade offer. In relatively simple
setups with just one IP address and a single server for all traffic setups with just one IP address and a single server for all traffic
to a single hostname, this might allow a practical way for systems to a single hostname, this might allow a practical way for systems
based on the WebSocket protocol to be deployed. In more elaborate based on the WebSocket protocol to be deployed. In more elaborate
setups (e.g. with load balancers and multiple servers), a dedicated setups (e.g. with load balancers and multiple servers), a dedicated
set of hosts for WebSocket connections separate from the HTTP servers set of hosts for WebSocket connections separate from the HTTP servers
is probably easier to manage. At the time of writing of this is probably easier to manage. At the time of writing of this
specification, it should be noted that connections on port 80 and 443 specification, it should be noted that connections on port 80 and 443
have significantly different success rates, with connections on port have significantly different success rates, with connections on port
443 being significantly more likely to succeed, though this may 443 being significantly more likely to succeed, though this may
change with time. change with time.
1.9. Subprotocols using the WebSocket protocol 1.9. Subprotocols Using the WebSocket protocol
_This section is non-normative._ _This section is non-normative._
The client can request that the server use a specific subprotocol by The client can request that the server use a specific subprotocol by
including the |Sec-WebSocket-Protocol| field in its handshake. If it including the |Sec-WebSocket-Protocol| field in its handshake. If it
is specified, the server needs to include the same field and one of is specified, the server needs to include the same field and one of
the selected subprotocol values in its response for the connection to the selected subprotocol values in its response for the connection to
be established. be established.
These subprotocol names do not need to be registered, but if a These subprotocol names should be registered as per Section 11.10.
subprotocol is intended to be implemented by multiple independent To avoid potential collisions, it is recommended to use names that
WebSocket servers, potential clashes with the names of subprotocols contain the domain name of the subprotocol's originator. For
defined independently can be avoided by using names that contain the example, if Example Corporation were to create a Chat subprotocol to
domain name of the subprotocol's originator. For example, if Example be implemented by many servers around the Web, they could name it
Corporation were to create a Chat subprotocol to be implemented by "chat.example.com". If the Example Organization called their
many servers around the Web, they could name it "chat.example.com". competing subprotocol "example.org's chat protocol", then the two
If the Example Organization called their competing subprotocol subprotocols could be implemented by servers simultaneously, with the
"example.org's chat protocol", then the two subprotocols could be server dynamically selecting which subprotocol to use based on the
implemented by servers simultaneously, with the server dynamically value sent by the client.
selecting which subprotocol to use based on the value sent by the
client.
Subprotocols can be versioned in backwards-incompatible ways by Subprotocols can be versioned in backwards-incompatible ways by
changing the subprotocol name, e.g. going from "bookings.example.net" changing the subprotocol name, e.g. going from "bookings.example.net"
to "v2.bookings.example.net". These subprotocols would be considered to "v2.bookings.example.net". These subprotocols would be considered
completely separate by WebSocket clients. Backwards-compatible completely separate by WebSocket clients. Backwards-compatible
versioning can be implemented by reusing the same subprotocol string versioning can be implemented by reusing the same subprotocol string
but carefully designing the actual subprotocol to support this kind but carefully designing the actual subprotocol to support this kind
of extensibility. of extensibility.
2. Conformance requirements 2. Conformance Requirements
All diagrams, examples, and notes in this specification are non- All diagrams, examples, and notes in this specification are non-
normative, as are all sections explicitly marked non-normative. normative, as are all sections explicitly marked non-normative.
Everything else in this specification is normative. Everything else in this specification is normative.
The key words "MUST", "MUST NOT", "REQUIRED", "SHOULD", "SHOULD NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHOULD", "SHOULD NOT",
"RECOMMENDED", "MAY", and "OPTIONAL" in the normative parts of this "RECOMMENDED", "MAY", and "OPTIONAL" in the normative parts of this
document are to be interpreted as described in RFC2119. [RFC2119] document are to be interpreted as described in RFC2119. [RFC2119]
Requirements phrased in the imperative as part of algorithms (such as Requirements phrased in the imperative as part of algorithms (such as
skipping to change at page 13, line 31 skipping to change at page 13, line 31
be implemented in any manner, so long as the end result is be implemented in any manner, so long as the end result is
equivalent. (In particular, the algorithms defined in this equivalent. (In particular, the algorithms defined in this
specification are intended to be easy to follow, and not intended to specification are intended to be easy to follow, and not intended to
be performant.) be performant.)
Implementations MAY impose implementation-specific limits on Implementations MAY impose implementation-specific limits on
otherwise unconstrained inputs, e.g. to prevent denial of service otherwise unconstrained inputs, e.g. to prevent denial of service
attacks, to guard against running out of memory, or to work around attacks, to guard against running out of memory, or to work around
platform-specific limitations. platform-specific limitations.
The conformance classes defined by this specification are user agents The conformance classes defined by this specification are clients and
and servers. servers.
2.1. Terminology 2.1. Terminology
*ASCII* shall mean the character-encoding scheme defined in _ASCII_ shall mean the character-encoding scheme defined in
[ANSI.X3-4.1986]. [ANSI.X3-4.1986].
*Converting a string to ASCII lowercase* means replacing all This document makes reference to UTF-8 values and uses UTF-8
notational formats as defined in STD 63 [RFC3629].
Key Terms such as named algorithms or definitions are indicated like
_this_.
Names of headers or variables are indicated like |this|.
Variable values are indicated like /this/.
_Converting a string to ASCII lowercase_ means replacing all
characters in the range U+0041 to U+005A (i.e. LATIN CAPITAL LETTER characters in the range U+0041 to U+005A (i.e. LATIN CAPITAL LETTER
A to LATIN CAPITAL LETTER Z) with the corresponding characters in the A to LATIN CAPITAL LETTER Z) with the corresponding characters in the
range U+0061 to U+007A (i.e. LATIN SMALL LETTER A to LATIN SMALL range U+0061 to U+007A (i.e. LATIN SMALL LETTER A to LATIN SMALL
LETTER Z). LETTER Z).
Comparing two strings in an *ASCII case-insensitive* manner means Comparing two strings in an _ASCII case-insensitive_ manner means
comparing them exactly, code point for code point, except that the comparing them exactly, code point for code point, except that the
characters in the range U+0041 to U+005A (i.e. LATIN CAPITAL LETTER characters in the range U+0041 to U+005A (i.e. LATIN CAPITAL LETTER
A to LATIN CAPITAL LETTER Z) and the corresponding characters in the A to LATIN CAPITAL LETTER Z) and the corresponding characters in the
range U+0061 to U+007A (i.e. LATIN SMALL LETTER A to LATIN SMALL range U+0061 to U+007A (i.e. LATIN SMALL LETTER A to LATIN SMALL
LETTER Z) are considered to also match. LETTER Z) are considered to also match.
The term "URI" is used in this document as defined in [RFC3986]. The term "URI" is used in this document as defined in [RFC3986].
When an implementation is required to _send_ data as part of the When an implementation is required to _send_ data as part of the
WebSocket protocol, the implementation MAY delay the actual WebSocket protocol, the implementation MAY delay the actual
transmission arbitrarily, e.g. buffering data so as to send fewer IP transmission arbitrarily, e.g. buffering data so as to send fewer IP
packets. packets.
3. WebSocket URIs 3. WebSocket URIs
3.1. Parsing WebSocket URIs This specification defines two URI schemes, using the ABNF syntax
defined in RFC 5234 [RFC5234], and terminology and ABNF productions
The steps to *parse a WebSocket URI's components* from a string /uri/ defined by the URI specification RFC 3986 [RFC3986].
are as follows. These steps return either a /host/, a /port/, a
/resource name/, and a /secure/ flag, or they fail.
1. If the /uri/ string is not an absolute URI, then fail this
algorithm. [RFC3986]
2. Resolve the /uri/ string using the resolve a Web address
algorithm defined by the Web addresses specification, with the
URI character encoding set to UTF-8. [RFC3629] [RFC3986]
[RFC3987]
NOTE: It doesn't matter what it is resolved relative to, since
we already know it is an absolute URI at this point.
3. If /uri/ does not have a <scheme> component whose value, when
converted to ASCII lowercase, is either "ws" or "wss", then fail
this algorithm.
4. If /uri/ has a <fragment> component, then fail this algorithm.
5. If the <scheme> component of /uri/ is "ws", set /secure/ to
false; otherwise, if the <scheme> component is "wss", set
/secure/ to true; if neither of the above apply, fail this
algorithm.
6. Let /host/ be the value of the <host> component of /uri/,
converted to ASCII lowercase.
7. If /uri/ has a <port> component, then let /port/ be that
component's value; otherwise, there is no explicit /port/.
8. If there is no explicit /port/, then: if /secure/ is false, let
/port/ be 80, otherwise let /port/ be 443.
9. Let /resource name/ be the value of the <path> component (which
might be empty) of /uri/.
10. If /resource name/ is the empty string, set it to a single
character U+002F SOLIDUS (/).
11. If /uri/ has a <query> component, then append a single U+003F
QUESTION MARK character (?) to /resource name/, followed by the
value of the <query> component.
12. Return /host/, /port/, /resource name/, and /secure/.
3.2. Constructing WebSocket URIs
The steps to *construct a WebSocket URI* from a /host/, a /port/, a
/resource name/, and a /secure/ flag, are as follows:
1. Let /uri/ be the empty string.
2. If the /secure/ flag is false, then append the string "ws://" to
/uri/. Otherwise, append the string "wss://" to /uri/.
3. Append /host/ to /uri/.
4. If the /secure/ flag is false and port is not 80, or if the
/secure/ flag is true and port is not 443, then append the string
":" followed by /port/ to /uri/.
5. Append /resource name/ to /uri/. ws-URI = "ws:" "//" host [ ":" port ] path [ "?" query ]
wss-URI = "ws:" "//" host [ ":" port ] path [ "?" query ]
6. Return /uri/. host = <host, defined in [RFC3986], Section 3.2.2>
port = <host, defined in [RFC3986], Section 3.2.3>
path = <path-abempty, defined in [RFC3986], Section 3.3>
query = <query, defined in [RFC3986], Section 3.4>
3.3. Valid WebSocket URIs The port component is OPTIONAL; the default for "ws" is port 80,
while the default for "wss" is port 443.
For a WebSocket URI to be considered valid, the following conditions The URI is called "secure" if the scheme component matches "wss"
MUST hold. case-insensitively.
o The /host/ MUST be ASCII-only (i.e. it MUST have been punycode- The "resource-name" can be constructed by concatenating
encoded [RFC3492] already if necessary, and MUST NOT contain any
characters above U+007E).
o The /resource name/ string MUST be a non-empty string of "/" if the path component is empty
characters in the range U+0021 to U+007E and MUST start with a the path component
U+002F SOLIDUS character (/). "?" if the query component is non-empty
the query component
Any WebSocket URIs not meeting the above criteria are considered Fragment identifiers are meaningless in the context of WebSocket
invalid. A client MUST NOT attempt to make a connection to an URIs, and MUST NOT be used on these URIs. The character "#" in URIs
invalid WebSocket URI. A client SHOULD attempt to parse a URI MUST be escaped as %23 if used as part of the query component.
obtained from any external source (such as a web site or a user)
using the steps specified in Section 3.1 to obtain a valid WebSocket
URI, but MUST NOT attempt to connect with such an unparsed URI, and
instead only use the parsed version and only if that version is
considered valid by the criteria above.
4. Data Framing 4. Data Framing
4.1. Overview 4.1. Overview
In the WebSocket protocol, data is transmitted using a sequence of In the WebSocket protocol, data is transmitted using a sequence of
frames. Frames sent from the client to the server are masked to frames. Frames sent from the client to the server are masked to
avoid confusing network intermediaries, such as intercepting proxies. avoid confusing network intermediaries, such as intercepting proxies.
Frames sent from the server to the client are not masked. Frames sent from the server to the client are not masked.
The base framing protocol defines a frame type with an opcode, a The base framing protocol defines a frame type with an opcode, a
payload length, and designated locations for extension and payload length, and designated locations for extension and
application data, which together define the _payload_ data. Certain application data, which together define the _payload_ data. Certain
bits and opcodes are reserved for future expansion of the protocol. bits and opcodes are reserved for future expansion of the protocol.
As such, in the absence of extensions negotiated during the opening
handshake (Section 5), all reserved bits MUST be 0 and reserved
opcode values MUST NOT be used.
A data frame MAY be transmitted by either the client or the server at A data frame MAY be transmitted by either the client or the server at
any time after handshake completion and before that endpoint has sent any time after opening handshake completion and before that endpoint
a close message (Section 4.5.1). has sent a close frame (Section 4.5.1).
4.2. Base Framing Protocol 4.2. Base Framing Protocol
This wire format for the data transfer part is described by the ABNF This wire format for the data transfer part is described by the ABNF
[RFC5234] given in detail in this section. A high level overview of [RFC5234] given in detail in this section. A high level overview of
the framing is given in the following figure. the framing is given in the following figure.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-------+-+-------------+-------------------------------+ +-+-+-+-+-------+-+-------------+-------------------------------+
skipping to change at page 18, line 12 skipping to change at page 17, line 12
| Payload Data continued ... | | Payload Data continued ... |
+---------------------------------------------------------------+ +---------------------------------------------------------------+
FIN: 1 bit FIN: 1 bit
Indicates that this is the final fragment in a message. The first Indicates that this is the final fragment in a message. The first
fragment MAY also be the final fragment. fragment MAY also be the final fragment.
RSV1, RSV2, RSV3: 1 bit each RSV1, RSV2, RSV3: 1 bit each
Must be 0 unless an extension is negotiated which defines meanings MUST be 0 unless an extension is negotiated which defines meanings
for non-zero values for non-zero values. If a nonzero value is received and none of
the negotiated extensions defines the meaning of such a nonzero
value, the receiving endpoint MUST ignore that value.
Opcode: 4 bits Opcode: 4 bits
Defines the interpretation of the payload data Defines the interpretation of the payload data. If an unknown
opcode is received, the receiving endpoint MUST ignore that frame.
The following values are defined.
* %x0 denotes a continuation frame
* %x1 denotes a text frame
* %x2 denotes a binary frame
* %x3-7 are reserved for further non-control frames
* %x8 denotes a connection close
* %x9 denotes a ping
* %xA denotes a pong
* %xB-F are reserved for further control frames
Mask: 1 bit Mask: 1 bit
Defines whether the payload data is masked. If set to 1, a Defines whether the payload data is masked. If set to 1, a
masking key is present in Masking-key, and this is used to unmask masking key is present in masking-key, and this is used to unmask
the payload data as per Section 4.3. All frames sent from client the payload data as per Section 4.3. All frames sent from client
to server have this bit set to 1. to server have this bit set to 1.
Payload length: 7 bits, 7+16 bits, or 7+64 bits Payload length: 7 bits, 7+16 bits, or 7+64 bits
The length of the payload: if 0-125, that is the payload length. The length of the payload data, in bytes: if 0-125, that is the
If 126, the following 2 bytes interpreted as a 16 bit unsigned payload length. If 126, the following 2 bytes interpreted as a 16
integer are the payload length. If 127, the following 8 bytes bit unsigned integer are the payload length. If 127, the
interpreted as a 64-bit unsigned integer (the most significant bit following 8 bytes interpreted as a 64-bit unsigned integer (the
MUST be 0) are the payload length. Multibyte length quantities most significant bit MUST be 0) are the payload length. Multibyte
are expressed in network byte order. The payload length is the length quantities are expressed in network byte order. The
length of the Extension data + the length of the Application data. payload length is the length of the extension data + the length of
The length of the Extension data may be zero, in which case the the application data. The length of the extension data may be
Payload length is the length of the Application data. The length zero, in which case the payload length is the length of the
of this field is always at least 7 bits. If the value of the application data.
first 7 bits is 0-125, the length of this field is 7 bits. If the
value is 126, there exist 16 additional bits with a 16-bit length.
If the value is 127, there exist 64 additional bits with a 63-bit
length (the most significant bit MUST be 0).
Masking-key: 0 or 4 bytes Masking-key: 0 or 4 bytes
All frames sent from the client to the server are masked by a 32- All frames sent from the client to the server are masked by a 32-
bit value that is contained within the frame. This field is bit value that is contained within the frame. This field is
present if the Mask bit is set to 1, and is absent if the Mask bit present if the mask bit is set to 1, and is absent if the mask bit
is set to 0. See Section 4.3 for further information on client- is set to 0. See Section 4.3 for further information on client-
to-server masking. to-server masking.
Payload data: n bytes Payload data: (x+y) bytes
The payload data is defined as Extension Data concatenated with The payload data is defined as extension data concatenated with
Application Data. application data.
Extension data: n bytes Extension data: x bytes
The extension data is 0 bytes unless an extension has been The extension data is 0 bytes unless an extension has been
negotiated. Any extension MUST specify the length of the negotiated. Any extension MUST specify the length of the
extension data, or how that length may be calculated, and how the extension data, or how that length may be calculated, and how the
extension use MUST be negotiated during the handshake. If extension use MUST be negotiated during the opening handshake. If
present, the extension data is included in the total payload present, the extension data is included in the total payload
length. length.
Application data: n bytes Application data: y bytes
Arbitrary application data, taking up the remainder of the frame Arbitrary application data, taking up the remainder of the frame
after any extension data. The length of the Application data is after any extension data. The length of the application data is
equal to the payload length minus the length of the Extension equal to the payload length minus the length of the extension
data. data.
The base framing protocol is formally defined by the following ABNF The base framing protocol is formally defined by the following ABNF
[RFC5234]: [RFC5234]:
ws-frame = frame-fin ws-frame = frame-fin
frame-rsv1 frame-rsv1
frame-rsv2 frame-rsv2
frame-rsv3 frame-rsv3
frame-opcode frame-opcode
frame-masked frame-masked
frame-payload-length frame-payload-length
[ frame-masking-key ] [ frame-masking-key ]
frame-payload-data frame-payload-data
frame-fin = %x0 ; more frames of this message follow frame-fin = %x0 ; more frames of this message follow
/ %x1 ; final frame of message / %x1 ; final frame of this message
frame-rsv1 = %x0 ; 1 bit, MUST be 0 frame-rsv1 = %x0 ; 1 bit, MUST be 0
frame-rsv2 = %x0 ; 1 bit, MUST be 0 frame-rsv2 = %x0 ; 1 bit, MUST be 0
frame-rsv3 = %x0 ; 1 bit, MUST be 0 frame-rsv3 = %x0 ; 1 bit, MUST be 0
frame-opcode = %x0 ; continuation frame frame-opcode = %x0 ; continuation frame
/ %x1 ; text frame / %x1 ; text frame
/ %x2 ; binary frame / %x2 ; binary frame
/ %3-7 ; reserved for further non-control frames / %x3-7 ; reserved for further non-control frames
/ %x8 ; connection close / %x8 ; connection close
/ %x9 ; ping / %x9 ; ping
/ %xA ; pong / %xA ; pong
/ %xB-F ; reserved for further control frames / %xB-F ; reserved for further control frames
frame-masked = %x0 ; frame is not masked, no frame-masking-key frame-masked = %x0 ; frame is not masked, no frame-masking-key
= %x1 ; frame is masked, frame-masking-key present / %x1 ; frame is masked, frame-masking-key present
frame-payload-length = %x00-7D frame-payload-length = %x00-7D
/ %x7E frame-payload-length-16 / %x7E frame-payload-length-16
/ %x7F frame-payload-length-63 / %x7F frame-payload-length-63
frame-payload-length-16 = %x0000-FFFF frame-payload-length-16 = %x0000-FFFF
frame-payload-length-63 = %x0000000000000000-7FFFFFFFFFFFFFFF frame-payload-length-63 = %x0000000000000000-7FFFFFFFFFFFFFFF
frame-masking-key = <4>( %0x00-FF ) ; present only if frame-masked is 1 frame-masking-key = 4( %0x00-FF ) ; present only if frame-masked is 1
frame-payload-data = (frame-masked-extension-data frame-payload-data = (frame-masked-extension-data
frame-masked-application-data) ; frame-masked 1 frame-masked-application-data) ; frame-masked 1
/ (frame-unmasked-extension-data / (frame-unmasked-extension-data
frame-unmasked-application-data) ; frame-masked 0 frame-unmasked-application-data) ; frame-masked 0
frame-masked-extension-data = *( %x00-FF ) ; to be defined later frame-masked-extension-data = *( %x00-FF ) ; to be defined later
frame-masked-application-data = *( %x00-FF ) frame-masked-application-data = *( %x00-FF )
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in Section 4.2. in Section 4.2.
The masking key is contained completely within the frame, as defined The masking key is contained completely within the frame, as defined
in Section 4.2 as frame-masking-key. It is used to mask the payload in Section 4.2 as frame-masking-key. It is used to mask the payload
data defined in the same section as frame-payload-data, which data defined in the same section as frame-payload-data, which
includes extension and application data. includes extension and application data.
The masking key is a 32-bit value chosen at random by the client. The masking key is a 32-bit value chosen at random by the client.
The masking key MUST be derived from a strong source of entropy, and The masking key MUST be derived from a strong source of entropy, and
the masking key for a given frame MUST NOT make it simple for a the masking key for a given frame MUST NOT make it simple for a
server to predict the masking key for a subsequent frame. server to predict the masking key for a subsequent frame. RFC 4086
[RFC4086] discusses what entails a suitable source of entropy for
security-sensitive applications.
The masking does not affect the length of the payload data. To The masking does not affect the length of the payload data. To
convert masked data into unmasked data, or vice versa, the following convert masked data into unmasked data, or vice versa, the following
algorithm is applied. The same algorithm applies regardless of the algorithm is applied. The same algorithm applies regardless of the
direction of the translation - e.g. the same steps are applied to direction of the translation - e.g. the same steps are applied to
mask the data as to unmask the data. mask the data as to unmask the data.
Octet i of the transformed data ("transformed-octet-i") is the XOR of Octet i of the transformed data ("transformed-octet-i") is the XOR of
octet i of the original data ("original-octet-i") with octet i modulo octet i of the original data ("original-octet-i") with octet i modulo
4 of the masking key ("masking-key-octet-j"): 4 of the masking key ("masking-key-octet-j"):
j = i MOD 4 j = i MOD 4
transformed-octet-i = original-octet-i XOR masking-key-octet-j transformed-octet-i = original-octet-i XOR masking-key-octet-j
When preparing a masked frame, the client MUST pick a fresh masking When preparing a masked frame, the client MUST pick a fresh masking
key uniformly at random from the set of allowed 32-bit values. The key uniformly at random from the set of allowed 32-bit values. The
unpredictability of the masking-nonce is essential to prevent the unpredictability of the masking key is essential to prevent the
author of malicious application data from selecting the bytes that author of malicious applications from selecting the bytes that appear
appear on the wire. on the wire.
The payload length, indicated in the framing as frame-payload-length, The payload length, indicated in the framing as frame-payload-length,
does NOT include the length of the masking key. It is the length of does NOT include the length of the masking key. It is the length of
the payload data, e.g. the number of bytes following the masking key. the payload data, e.g. the number of bytes following the masking key.
4.4. Fragmentation 4.4. Fragmentation
The primary purpose of fragmentation is to allow sending a message The primary purpose of fragmentation is to allow sending a message
that is of unknown size when the message is started without having to that is of unknown size when the message is started without having to
buffer that message. If messages couldn't be fragmented, then an buffer that message. If messages couldn't be fragmented, then an
skipping to change at page 22, line 8 skipping to change at page 21, line 29
channel. channel.
The following rules apply to fragmentation: The following rules apply to fragmentation:
o An unfragmented message consists of a single frame with the FIN o An unfragmented message consists of a single frame with the FIN
bit set and an opcode other than 0. bit set and an opcode other than 0.
o A fragmented message consists of a single frame with the FIN bit o A fragmented message consists of a single frame with the FIN bit
clear and an opcode other than 0, followed by zero or more frames clear and an opcode other than 0, followed by zero or more frames
with the FIN bit clear and the opcode set to 0, and terminated by with the FIN bit clear and the opcode set to 0, and terminated by
a single frame with the FIN bit set and an opcode of 0. Its a single frame with the FIN bit set and an opcode of 0. A
content is the concatenation of the application data (and any fragmented message is conceptually equivalent to a single larger
extension data that may be present) from each of those frames in message whose payload is equal to the concatenation of the
order. As an example, for a text message sent as three fragments, payloads of the fragments in order, however in the presence of
the first fragment would have an opcode of 0x4 and a FIN bit extensions this may not hold true as the extension defines the
clear, the second fragment would have an opcode of 0x0 and a FIN interpretation of the extension data present. For instance,
bit clear, and the third fragment would have an opcode of 0x0 and extension data may only be present at the beginning of the first
a FIN bit that is set. fragment and apply to subsequent fragments, or there may be
extension data present in each of the fragments that applies only
to that particular fragment. Setting aside the issue of
extensions, the following example demonstrates how fragmentation
works.
o EXAMPLE: For a text message sent as three fragments, the first
fragment would have an opcode of 0x1 and a FIN bit clear, the
second fragment would have an opcode of 0x0 and a FIN bit clear,
and the third fragment would have an opcode of 0x0 and a FIN bit
that is set.
o Control frames MAY be injected in the middle of a fragmented o Control frames MAY be injected in the middle of a fragmented
message. Control frames themselves MUST NOT be fragmented. message. Control frames themselves MUST NOT be fragmented.
o Message fragments MUST be delivered to the recipient in the order
sent by the sender.
o An endpoint MUST be capable of handling control frames in the o An endpoint MUST be capable of handling control frames in the
middle of a fragmented message. middle of a fragmented message.
o _Note: if control frames could not be interjected, the latency of o _Note: if control frames could not be interjected, the latency of
a ping, for example, would be very long if behind a large message. a ping, for example, would be very long if behind a large message.
Hence, the requirement of handling control frames in the middle of Hence, the requirement of handling control frames in the middle of
a fragmented message._ a fragmented message._
o A sender MAY create fragments of any size for non control o A sender MAY create fragments of any size for non-control
messages. messages.
o Clients and servers MUST support receiving both fragmented and o Clients and servers MUST support receiving both fragmented and
unfragmented messages. unfragmented messages.
o As control frames cannot be fragmented, an intermediary MUST NOT o As control frames cannot be fragmented, an intermediary MUST NOT
attempt to change the fragmentation of a control frame. attempt to change the fragmentation of a control frame.
o An intermediary MUST NOT change the fragmentation of a message if o An intermediary MUST NOT change the fragmentation of a message if
any reserved bit values are used and the meaning of these values any reserved bit values are used and the meaning of these values
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a message MUST be either text or binary, or one of the reserved a message MUST be either text or binary, or one of the reserved
opcodes. opcodes.
4.5. Control Frames 4.5. Control Frames
Control frames are identified by opcodes where the most significant Control frames are identified by opcodes where the most significant
bit of the opcode is 1. Currently defined opcodes for control frames bit of the opcode is 1. Currently defined opcodes for control frames
include 0x8 (Close), 0x9 (Ping), and 0xA (Pong). Opcodes 0xB-0xF are include 0x8 (Close), 0x9 (Ping), and 0xA (Pong). Opcodes 0xB-0xF are
reserved for further control frames yet to be defined. reserved for further control frames yet to be defined.
Control frames are used to communicate state about the websocket. Control frames are used to communicate state about the WebSocket.
Control frames can be interjected in the middle of a fragmented Control frames can be interjected in the middle of a fragmented
message. message.
All control frames MUST have a payload length of 125 bytes or less All control frames MUST have a payload length of 125 bytes or less
and MUST NOT be fragmented. and MUST NOT be fragmented.
4.5.1. Close 4.5.1. Close
The Close message contains an opcode of 0x8. The Close frame contains an opcode of 0x8.
The Close message MAY contain a body (the "application data" portion The Close frame MAY contain a body (the "application data" portion of
of the frame) that indicates a reason for closing, such as an the frame) that indicates a reason for closing, such as an endpoint
endpoint shutting down, an endpoint having received a message too shutting down, an endpoint having received a frame too large, or an
large, or an endpoint having received a message that does not conform endpoint having received a frame that does not conform to the format
to the format expected by the other endpoint. If there is a body, expected by the other endpoint. If there is a body, the first two
the first two bytes of the body MUST be a 2-byte integer (in network bytes of the body MUST be a 2-byte unsigned integer (in network byte
byte order) representing a status code defined in Section 7.4. order) representing a status code with value /code/ defined in
Following the 2-byte integer the body MAY contain UTF-8 encoded data, Section 7.4. Following the 2-byte integer the body MAY contain UTF-8
the interpretation of which is not defined by this specification. encoded data with value /reason/, the interpretation of which is not
This data is not necessarily human readable, but may be useful for defined by this specification. This data is not necessarily human
debugging or passing information relevant to the script that opened readable, but may be useful for debugging or passing information
the connection. relevant to the script that opened the connection.
The application MUST NOT send any more data frames after sending a The application MUST NOT send any more data frames after sending a
close message. close frame.
If an endpoint receives a Close message and that endpoint did not If an endpoint receives a Close frame and that endpoint did not
previously send a Close message, the endpoint MUST send a Close previously send a Close frame, the endpoint MUST send a Close frame
message in response. It SHOULD do so as soon as is practical. in response. It SHOULD do so as soon as is practical. An endpoint
MAY delay sending a close frame until its current message is sent
(for instance, if the majority of a fragmented message is already
sent, an endpoint MAY send the remaining fragments before sending a
Close frame). However, there is no guarantee that the endpoint which
has already sent a Close frame will continue to process data.
After both sending and receiving a close message, an endpoint After both sending and receiving a close message, an endpoint
considers the websocket connection closed, and SHOULD close the considers the WebSocket connection closed, and MUST close the
underlying TCP connection. underlying TCP connection. The server MUST close the underlying TCP
connection immediately; the client SHOULD wait for the server to
close the connection but MAY close the connection at any time after
sending and receiving a close message, e.g. if it has not received a
TCP close from the server in a reasonable time period.
If a client and server both send a Close message at the same time, If a client and server both send a Close message at the same time,
both endpoints will have sent and received a Close message and should both endpoints will have sent and received a Close message and should
consider the websocket connection closed and close the underlying TCP consider the WebSocket connection closed and close the underlying TCP
connection. connection.
4.5.2. Ping 4.5.2. Ping
The Ping message contains an opcode of 0x9. The Ping frame contains an opcode of 0x9.
Upon receipt of a Ping message, an endpoint MUST send a Pong message Upon receipt of a Ping frame, an endpoint MUST send a Pong frame in
in response. It SHOULD do so as soon as is practical. The message response. It SHOULD do so as soon as is practical. Pong frames are
bodies (i.e. both the Extension data (if any) and the Application discussed in Section 4.5.3.
data) of the Ping and Pong MUST be the same.
An endpoint MAY send a Ping message any time after the connection is An endpoint MAY send a Ping frame any time after the connection is
established and before the connection is closed. NOTE: A ping established and before the connection is closed. NOTE: A ping frame
message may serve either as a keepalive, or to verify that the remote may serve either as a keepalive, or to verify that the remote
endpoint is still responsive. endpoint is still responsive.
4.5.3. Pong 4.5.3. Pong
The Pong message contains an opcode of 0xA. The Pong frame contains an opcode of 0xA.
Upon receipt of a Ping message, an endpoint MUST send a Pong message Section 4.5.2 details requirements that apply to both Ping and Pong
in response. It SHOULD do so as soon as is practical. The message frames.
bodies (i.e. both the Extension data (if any) and the Application
data) of the Ping and Pong MUST be the same. In the case multiple
Pings have been received, a Pong MUST be issued only in response to
the most recent Ping.
A Pong message MAY be sent unsolicited. This serves as a A Pong frame sent in response to a Ping frame must have identical
Application Data as found in the message body of the Ping frame being
replied to.
If an endpoint receives a Ping frame and has not yet sent Pong
frame(s) in response to previous Ping frame(s), the endpoint MAY
elect to send a Pong frame for only the most recently processed Ping
frame.
A Pong frame MAY be sent unsolicited. This serves as a
unidirectional heartbeat. A response to an unsolicited pong is not unidirectional heartbeat. A response to an unsolicited pong is not
expected. expected.
4.6. Data Frames 4.6. Data Frames
Data frames (e.g. non control frames) are identified by opcodes where Data frames (e.g. non-control frames) are identified by opcodes where
the most significant bit of the opcode is 0. Currently defined the most significant bit of the opcode is 0. Currently defined
opcodes for data frames include 0x1 (Text), 0x2 (Binary). Opcodes opcodes for data frames include 0x1 (Text), 0x2 (Binary). Opcodes
0x3-0x7 are reserved for further non-control frames yet to be 0x3-0x7 are reserved for further non-control frames yet to be
defined. defined.
Data frames carry application-layer or extension-layer data. The Data frames carry application-layer or extension-layer data. The
opcode determines the interpretation of the data: opcode determines the interpretation of the data:
Text Text
skipping to change at page 25, line 44 skipping to change at page 25, line 44
* 0x82 0x7E 0x0100 [256 bytes of binary data] * 0x82 0x7E 0x0100 [256 bytes of binary data]
o 64KiB binary message in a single unmasked frame o 64KiB binary message in a single unmasked frame
* 0x82 0x7F 0x0000000000010000 [65536 bytes of binary data] * 0x82 0x7F 0x0000000000010000 [65536 bytes of binary data]
4.8. Extensibility 4.8. Extensibility
The protocol is designed to allow for extensions, which will add The protocol is designed to allow for extensions, which will add
capabilities to the base protocols. The endpoints of a connection capabilities to the base protocols. The endpoints of a connection
MUST negotiate the use of any extensions during the handshake. This MUST negotiate the use of any extensions during the opening
specification provides opcodes 0x3 through 0x7 and 0xB through 0xF, handshake. This specification provides opcodes 0x3 through 0x7 and
the extension data field, and the frame-rsv1, frame-rsv2, and frame- 0xB through 0xF, the extension data field, and the frame-rsv1, frame-
rsv3 bits of the frame header for use by extensions. The negotiation rsv2, and frame-rsv3 bits of the frame header for use by extensions.
of extensions is discussed in further detail in Section 8.1. Below The negotiation of extensions is discussed in further detail in
are some anticipated uses of extensions. This list is neither Section 9.1. Below are some anticipated uses of extensions. This
complete nor proscriptive. list is neither complete nor proscriptive.
o Extension data may be placed in the payload before the application o Extension data may be placed in the payload data before the
data. application data.
o Reserved bits can be allocated for per-frame needs. o Reserved bits can be allocated for per-frame needs.
o Reserved opcode values can be defined. o Reserved opcode values can be defined.
o Reserved bits can be allocated to the opcode field if more opcode o Reserved bits can be allocated to the opcode field if more opcode
values are needed. values are needed.
o A reserved bit or an "extension" opcode can be defined which o A reserved bit or an "extension" opcode can be defined which
allocates additional bits out of the payload area to define larger allocates additional bits out of the payload data to define larger
opcodes or more per-frame bits. opcodes or more per-frame bits.
5. Opening Handshake 5. Opening Handshake
5.1. Client Requirements 5.1. Client Requirements
User agents running in controlled environments, e.g. browsers on To _Establish a WebSocket Connection_, a client opens a connection
mobile handsets tied to specific carriers, may offload the management and sends a handshake as defined in this section. A connection is
of the connection to another agent on the network. In such a defined to initially be in a CONNECTING state. A client will need to
situation, the user agent for the purposes of conformance is supply a /host/, /port/, /resource name/, and a /secure/ flag, which
considered to include both the handset software and any such agents. are the components of a WebSocket URI as discussed in Section 3,
along with a list of /protocols/ and /extensions/ to be used.
Additionally, if the client is a web browser, an /origin/ MUST be
supplied.
When the user agent is to *establish a WebSocket connection* given Clients running in controlled environments, e.g. browsers on mobile
either a WebSocket URI /uri/ or the constituent components of a URI handsets tied to specific carriers, may offload the management of the
as specified in Section 11, it MUST meet the following requirements. connection to another agent on the network. In such a situation, the
In the following text, we will use terms from Section 3 such as client for the purposes of conformance is considered to include both
"/host/" and "/secure/ flag" as defined in that section. the handset software and any such agents.
1. The WebSocket URI and its components derived by applying the When the client is to _Establish a WebSocket Connection_ given a set
steps defined in Section 3.3, or if the following algorithm was of (/host/, /port/, /resource name/, and /secure/ flag), along with a
supplied with the constituent components as defined in Section 11 list of /protocols/ and /extensions/ to be used, and an /origin/ in
then those components provided, MUST be valid according to the case of web browsers, it MUST open a connection, send an opening
Section 3.3. If any of the requirements are not met, the client handshake, and read the server's handshake in response. The exact
MUST fail the WebSocket connection and abort these steps. requirements of how the connection should be opened, what should be
sent in the opening handshake, and how the server's response should
be interpreted, are as follows in this section. In the following
text, we will use terms from Section 3 such as "/host/" and "/secure/
flag" as defined in that section.
2. If the user agent already has a WebSocket connection to the 1. The components of the WebSocket URI passed into this algorithm
remote host (IP address) identified by /host/ and port /port/ (/host/, /port/, /resource name/ and /secure/ flag) MUST be valid
pair, even if the remote host is known by another name, the user according to the specification of WebSocket URIs specified in
agent MUST wait until that connection has been established or for Section 3. If any of the components are invalid, the client MUST
that connection to have failed. There MUST be no more than one _Fail the WebSocket Connection_ and abort these steps.
connection in a CONNECTING state. If multiple connections to the
same IP address are attempted simultaneously, the user agent MUST
serialize them so that there is no more than one connection at a
time running through the following steps.
If the user agent cannot determine the IP address of the remote 2. If the client already has a WebSocket connection to the remote
host (for example because all communication is being done through host (IP address) identified by /host/ and port /port/ pair, even
a proxy server that performs DNS queries itself), then the user if the remote host is known by another name, the client MUST wait
agent MUST assume for the purposes of this step that each host until that connection has been established or for that connection
name refers to a distinct remote host, but should instead limit to have failed. There MUST be no more than one connection in a
the total number of simultaneous connections that are not CONNECTING state. If multiple connections to the same IP address
established to a reasonably low number (e.g., in a Web browser, are attempted simultaneously, the client MUST serialize them so
to the number of tabs the user has open). that there is no more than one connection at a time running
through the following steps.
If the client cannot determine the IP address of the remote host
(for example because all communication is being done through a
proxy server that performs DNS queries itself), then the client
MUST assume for the purposes of this step that each host name
refers to a distinct remote host, and should instead limit the
total number of simultaneous connections that are not established
to a reasonably low number (e.g., in a Web browser, simultaneous
pending connections to a.example.com and b.example.com would be
allowed, but if thirty connections are requested, that may not be
allowed. The limit should consider the number of tabs the user
has open.
NOTE: This makes it harder for a script to perform a denial of NOTE: This makes it harder for a script to perform a denial of
service attack by just opening a large number of WebSocket service attack by just opening a large number of WebSocket
connections to a remote host. A server can further reduce the connections to a remote host. A server can further reduce the
load on itself when attacked by making use of this by pausing load on itself when attacked by making use of this by pausing
before closing the connection, as that will reduce the rate at before closing the connection, as that will reduce the rate at
which the client reconnects. which the client reconnects.
NOTE: There is no limit to the number of established WebSocket NOTE: There is no limit to the number of established WebSocket
connections a user agent can have with a single remote host. connections a client can have with a single remote host. Servers
Servers can refuse to accept connections from hosts with an can refuse to accept connections from hosts with an excessive
excessive number of existing connections, or disconnect resource- number of existing connections, or disconnect resource-hogging
hogging connections when suffering high load. connections when suffering high load.
3. _Proxy Usage_: If the user agent is configured to use a proxy 3. _Proxy Usage_: If the client is configured to use a proxy when
when using the WebSocket protocol to connect to host /host/ using the WebSocket protocol to connect to host /host/ and/or
and/or port /port/, then the user agent SHOULD connect to that port /port/, then the client SHOULD connect to that proxy and ask
proxy and ask it to open a TCP connection to the host given by it to open a TCP connection to the host given by /host/ and the
/host/ and the port given by /port/. port given by /port/.
EXAMPLE: For example, if the user agent uses an HTTP proxy for EXAMPLE: For example, if the client uses an HTTP proxy for all
all traffic, then if it was to try to connect to port 80 on traffic, then if it was to try to connect to port 80 on server
server example.com, it might send the following lines to the example.com, it might send the following lines to the proxy
proxy server: server:
CONNECT example.com:80 HTTP/1.1 CONNECT example.com:80 HTTP/1.1
Host: example.com Host: example.com
If there was a password, the connection might look like: If there was a password, the connection might look like:
CONNECT example.com:80 HTTP/1.1 CONNECT example.com:80 HTTP/1.1
Host: example.com Host: example.com
Proxy-authorization: Basic ZWRuYW1vZGU6bm9jYXBlcyE= Proxy-authorization: Basic ZWRuYW1vZGU6bm9jYXBlcyE=
If the user agent is not configured to use a proxy, then a direct If the client is not configured to use a proxy, then a direct TCP
TCP connection SHOULD be opened to the host given by /host/ and connection SHOULD be opened to the host given by /host/ and the
the port given by /port/. port given by /port/.
NOTE: Implementations that do not expose explicit UI for NOTE: Implementations that do not expose explicit UI for
selecting a proxy for WebSocket connections separate from other selecting a proxy for WebSocket connections separate from other
proxies are encouraged to use a SOCKS proxy for WebSocket proxies are encouraged to use a SOCKS proxy for WebSocket
connections, if available, or failing that, to prefer the proxy connections, if available, or failing that, to prefer the proxy
configured for HTTPS connections over the proxy configured for configured for HTTPS connections over the proxy configured for
HTTP connections. HTTP connections.
For the purpose of proxy autoconfiguration scripts, the URI to For the purpose of proxy autoconfiguration scripts, the URI to
pass the function MUST be constructed from /host/, /port/, pass the function MUST be constructed from /host/, /port/,
/resource name/, and the /secure/ flag using the steps to /resource name/, and the /secure/ flag using the definition of a
construct a WebSocket URI as given in Section 3.2. WebSocket URI as given in Section 3.
NOTE: The WebSocket protocol can be identified in proxy NOTE: The WebSocket protocol can be identified in proxy
autoconfiguration scripts from the scheme ("ws:" for unencrypted autoconfiguration scripts from the scheme ("ws:" for unencrypted
connections and "wss:" for encrypted connections). connections and "wss:" for encrypted connections).
4. If the connection could not be opened, either because a direct 4. If the connection could not be opened, either because a direct
connection failed or because any proxy used returned an error, connection failed or because any proxy used returned an error,
then the user agent MUST fail the WebSocket connection and abort then the client MUST _Fail the WebSocket Connection_ and abort
the connection attempt. the connection attempt.
5. If /secure/ is true, the user agent MUST perform a TLS handshake 5. If /secure/ is true, the client MUST perform a TLS handshake over
over the connection [RFC2818]. If this fails (e.g. the server's the connection after opening the connection and before sending
certificate could not be verified), then the user agent MUST fail the handshake data [RFC2818]. If this fails (e.g. the server's
the WebSocket connection and abort the connection. Otherwise, certificate could not be verified), then the client MUST _Fail
the WebSocket Connection_ and abort the connection. Otherwise,
all further communication on this channel MUST run through the all further communication on this channel MUST run through the
encrypted tunnel. [RFC5246] encrypted tunnel. [RFC5246]
User agents MUST use the Server Name Indication extension in the Clients MUST use the Server Name Indication extension in the TLS
TLS handshake. [RFC6066] handshake. [RFC6066]
Once a connection to the server has been established (including a Once a connection to the server has been established (including a
connection via a proxy or over a TLS-encrypted tunnel), the client connection via a proxy or over a TLS-encrypted tunnel), the client
MUST send a handshake to the server. The handshake consists of an MUST send an opening handshake to the server. The handshake consists
HTTP upgrade request, along with a list of required and optional of an HTTP upgrade request, along with a list of required and
headers. The requirements for this handshake are as follows. optional headers. The requirements for this handshake are as
follows.
1. The handshake MUST be a valid HTTP request as specified by 1. The handshake MUST be a valid HTTP request as specified by
[RFC2616]. [RFC2616].
2. The Method of the request MUST be GET and the HTTP version MUST 2. The Method of the request MUST be GET and the HTTP version MUST
be at least 1.1. be at least 1.1.
For example, if the WebSocket URI is "ws://example.com/chat", For example, if the WebSocket URI is "ws://example.com/chat",
The first line sent should be "GET /chat HTTP/1.1" The first line sent should be "GET /chat HTTP/1.1"
3. The request MUST contain a "Request-URI" as part of the GET 3. The request MUST contain a "Request-URI" as part of the GET
method. This MUST match the /resource name/ Section 3. method. This MUST match the /resource name/ Section 3 (a
relative URI), or be an absolute URI that, when parsed, has a
matching /resource name/ as well as matching /host/, /port/, and
appropriate scheme (ws or wss).
4. The request MUST contain a "Host" header whose value is equal to 4. The request MUST contain a "Host" header whose value is equal to
/host/ /host/.
5. The request MUST contain an "Upgrade" header whose value is 5. The request MUST contain an "Upgrade" header whose value is
equal to "websocket". equal to "websocket".
6. The request MUST contain a "Connection" header whose value MUST 6. The request MUST contain a "Connection" header whose value MUST
include the "Upgrade" token. include the "Upgrade" token.
7. The request MUST include a header with the name "Sec-WebSocket- 7. The request MUST include a header with the name "Sec-WebSocket-
Key". The value of this header MUST be a nonce consisting of a Key". The value of this header MUST be a nonce consisting of a
randomly selected 16-byte value that has been base64-encoded randomly selected 16-byte value that has been base64-encoded
skipping to change at page 30, line 19 skipping to change at page 30, line 40
8. The request MUST include a header with the name "Sec-WebSocket- 8. The request MUST include a header with the name "Sec-WebSocket-
Origin" if the request is coming from a browser client. If the Origin" if the request is coming from a browser client. If the
connection is from a non-browser client, the request MAY include connection is from a non-browser client, the request MAY include
this header if the semantics of that client match the use-case this header if the semantics of that client match the use-case
described here for browser clients. The value of this header described here for browser clients. The value of this header
MUST be the ASCII serialization of origin of the context in MUST be the ASCII serialization of origin of the context in
which the code establishing the connection is running, and MUST which the code establishing the connection is running, and MUST
be lower-case. The value MUST NOT contain letters in the range be lower-case. The value MUST NOT contain letters in the range
U+0041 to U+005A (i.e. LATIN CAPITAL LETTER A to LATIN CAPITAL U+0041 to U+005A (i.e. LATIN CAPITAL LETTER A to LATIN CAPITAL
LETTER Z) [I-D.ietf-websec-origin]. LETTER Z) [I-D.ietf-websec-origin]. The ABNF is as defined in
Section 6.1 of [I-D.ietf-websec-origin].
As an example, if code is running on www.example.com attempting As an example, if code is running on www.example.com attempting
to establish a connection to ww2.example.com, the value of the to establish a connection to ww2.example.com, the value of the
header would be "http://www.example.com". header would be "http://www.example.com".
9. The request MUST include a header with the name "Sec-WebSocket- 9. The request MUST include a header with the name "Sec-WebSocket-
Version". The value of this header MUST be 7. Version". The value of this header MUST be 8.
10. The request MAY include a header with the name "Sec-WebSocket- 10. The request MAY include a header with the name "Sec-WebSocket-
Protocol". If present, this value indicates the subprotocol(s) Protocol". If present, this value indicates the subprotocol(s)
the client wishes to speak. The elements that comprise this the client wishes to speak, ordered by preference. The elements
value MUST be non-empty strings with characters in the range that comprise this value MUST be non-empty strings with
U+0021 to U+007E and MUST all be unique strings. The ABNF for characters in the range U+0021 to U+007E not including separator
the value of this header is 1#(token | quoted-string), where the characters as defined in [RFC2616], and MUST all be unique
definitions of constructs and rules are as given in [RFC2616]. strings. The ABNF for the value of this header is 1#token,
where the definitions of constructs and rules are as given in
[RFC2616].
11. The request MAY include a header with the name "Sec-WebSocket- 11. The request MAY include a header with the name "Sec-WebSocket-
Extensions". If present, this value indicates the protocol- Extensions". If present, this value indicates the protocol-
level extension(s) the client wishes to speak. The level extension(s) the client wishes to speak. The
interpretation and format of this header is described in interpretation and format of this header is described in
Section 8.1. Section 9.1.
12. The request MAY include headers associated with sending cookies, 12. The request MAY include headers associated with sending cookies,
as defined by the appropriate specifications as defined by the appropriate specifications
[I-D.ietf-httpstate-cookie]. [I-D.ietf-httpstate-cookie]. These headers are referred to as
_Headers to Send Appropriate Cookies_.
Once the client's opening handshake has been sent, the client MUST Once the client's opening handshake has been sent, the client MUST
wait for a response from the server before sending any further data. wait for a response from the server before sending any further data.
The client MUST validate the server's response as follows: The client MUST validate the server's response as follows:
o If the status code received from the server is not 101, the client 1. If the status code received from the server is not 101, the
handles the response per HTTP procedures. Otherwise, proceed as client handles the response per HTTP procedures. Otherwise,
follows. proceed as follows.
o If the response lacks an Upgrade header or the Upgrade header 2. If the response lacks an "Upgrade" header or the "Upgrade" header
contains a value that is not an ASCII case-insensitive match for contains a value that is not an ASCII case-insensitive match for
the value "websocket", the client MUST fail the WebSocket the value "websocket", the client MUST _Fail the WebSocket
connection. Connection _.
o If the response lacks a Connection header or the Connection header 3. If the response lacks a "Connection" header or the "Connection"
contains a value that is not an ASCII case-insensitive match for header contains a value that is not an ASCII case-insensitive
the value "Upgrade", the client MUST fail the WebSocket match for the value "Upgrade", the client MUST _Fail the
connection. WebSocket Connection_.
o If the response lacks a Sec-WebSocket-Accept header or the Sec- 4. If the response lacks a "Sec-WebSocket-Accept" header or the
WebSocket-Accept contains a value other than the base64-encoded "Sec-WebSocket-Accept" contains a value other than the base64-
SHA-1 of the concatenation of the Sec-WebSocket-Key (as a string, encoded SHA-1 of the concatenation of the "Sec-WebSocket-Key" (as
not base64-decoded) with the string "258EAFA5-E914-47DA-95CA- a string, not base64-decoded) with the string "258EAFA5-E914-
C5AB0DC85B11", the client MUST fail the WebSocket connection. 47DA-95CA-C5AB0DC85B11", the client MUST _Fail the WebSocket
Connection_
Where the algorithm above requires that a user agent fail the 5. If the response includes a "Sec-WebSocket-Extensions" header, and
WebSocket connection, the user agent MAY first read an arbitrary this header indicates the use of an extension that was not
number of further bytes from the connection (and then discard them) present in the client' handshake (the server has indicated an
before actually *failing the WebSocket connection*. Similarly, if a extension not requested by the client), the client MUST _Fail the
user agent can show that the bytes read from the connection so far WebSocket Connection_. (The parsing of this header to determine
are such that there is no subsequent sequence of bytes that the which extensions are requested is discussed in Section 9.1.)
server can send that would not result in the user agent being
required to *fail the WebSocket connection*, the user agent MAY
immediately *fail the WebSocket connection* without waiting for those
bytes.
NOTE: The previous paragraph is intended to make it conforming for If the server's response is validated as provided for above, it is
user agents to implement the algorithm in subtly different ways that said that _The WebSocket Connection is Established_ and that the
are equivalent in all ways except that they terminate the connection WebSocket Connection is in the OPEN state. The _Extensions In Use_
at earlier or later points. For example, it enables an is defined to be a (possibly empty) string, the value of which is
implementation to buffer the entire handshake response before equal to the value of the |Sec-WebSocket-Extensions| header supplied
checking it, or to verify each field as it is received rather than by the server's handshake, or the null value if that header was not
collecting all the fields and then checking them as a block. present in the server's handshake. The _Subprotocol In Use_ is
defined to be the value of the |Sec-WebSocket-Protocol| header in the
server's handshake, or the null value if that header was not present
in the server's handshake. Additionally, if any headers in the
server's handshake indicate that cookies should be set (as defined by
[I-D.ietf-httpstate-cookie]), these cookies are referred to as
_Cookies Set During the Server's Opening Handshake_.
5.2. Server-side requirements 5.2. Server-side Requirements
_This section only applies to servers._ _This section only applies to servers._
Servers MAY offload the management of the connection to other agents Servers MAY offload the management of the connection to other agents
on the network, for example load balancers and reverse proxies. In on the network, for example load balancers and reverse proxies. In
such a situation, the server for the purposes of conformance is such a situation, the server for the purposes of conformance is
considered to include all parts of the server-side infrastructure considered to include all parts of the server-side infrastructure
from the first device to terminate the TCP connection all the way to from the first device to terminate the TCP connection all the way to
the server that processes requests and sends responses. the server that processes requests and sends responses.
EXAMPLE: For example, a data center might have a server that responds EXAMPLE: For example, a data center might have a server that responds
to WebSocket requests with an appropriate handshake, and then passes to WebSocket requests with an appropriate handshake, and then passes
the connection to another server to actually process the data frames. the connection to another server to actually process the data frames.
For the purposes of this specification, the "server" is the For the purposes of this specification, the "server" is the
combination of both computers. combination of both computers.
5.2.1. Reading the client's opening handshake 5.2.1. Reading the Client's Opening Handshake
When a client starts a WebSocket connection, it sends its part of the When a client starts a WebSocket connection, it sends its part of the
opening handshake. The server must parse at least part of this opening handshake. The server must parse at least part of this
handshake in order to obtain the necessary information to generate handshake in order to obtain the necessary information to generate
the server part of the handshake. the server part of the handshake.
The client handshake consists of the following parts. If the server, The client's opening handshake consists of the following parts. If
while reading the handshake, finds that the client did not send a the server, while reading the handshake, finds that the client did
handshake that matches the description below, the server MUST abort not send a handshake that matches the description below, the server
the WebSocket connection. MUST stop processing the client's handshake, and return an HTTP
response with an appropriate error code (such as 400 Bad Request).
1. An HTTP/1.1 or higher GET request, including a "Request-URI" 1. An HTTP/1.1 or higher GET request, including a "Request-URI"
[RFC2616] that should be interpreted as a /resource name/ [RFC2616] that should be interpreted as a /resource name/
Section 3. Section 3.
2. A "Host" header containing the server's authority. 2. A "Host" header containing the server's authority.
3. A "Sec-WebSocket-Key" header with a base64-encoded value that, 3. A "Sec-WebSocket-Key" header with a base64-encoded value that,
when decoded, is 16 bytes in length. when decoded, is 16 bytes in length.
4. A "Sec-WebSocket-Version" header, with a value of 7. 4. A "Sec-WebSocket-Version" header, with a value of 8.
5. Optionally, a "Sec-WebSocket-Origin" header. This header is sent 5. Optionally, a "Sec-WebSocket-Origin" header. This header is sent
by all browser clients. A connection attempt lacking this header by all browser clients. A connection attempt lacking this header
SHOULD NOT be interpreted as coming from a browser client. SHOULD NOT be interpreted as coming from a browser client.
6. Optionally, a "Sec-WebSocket-Protocol" header, with a list of 6. Optionally, a "Sec-WebSocket-Protocol" header, with a list of
values indicating which protocols the client would like to speak, values indicating which protocols the client would like to speak,
ordered by preference. ordered by preference.
7. Optionally, a "Sec-WebSocket-Extensions" header, with a list of 7. Optionally, a "Sec-WebSocket-Extensions" header, with a list of
values indicating which extensions the client would like to values indicating which extensions the client would like to
speak. The interpretation of this header is discussed in speak. The interpretation of this header is discussed in
Section 8.1. Section 9.1.
8. Optionally, other headers, such as those used to send cookies to 8. Optionally, other headers, such as those used to send cookies to
a server. Unknown headers MUST be ignored. a server. Unknown headers MUST be ignored.
5.2.2. Sending the server's opening handshake 5.2.2. Sending the Server's Opening Handshake
When a client establishes a WebSocket connection to a server, the When a client establishes a WebSocket connection to a server, the
server MUST complete the following steps to accept the connection and server MUST complete the following steps to accept the connection and
send the server's opening handshake. send the server's opening handshake.
1. If the server supports encryption, perform a TLS handshake over 1. If the server supports encryption, perform a TLS handshake over
the connection. If this fails (e.g. the client indicated a host the connection. If this fails (e.g. the client indicated a host
name in the extended client hello "server_name" extension that name in the extended client hello "server_name" extension that
the server does not host), then close the connection; otherwise, the server does not host), then close the connection; otherwise,
all further communication for the connection (including the all further communication for the connection (including the
server handshake) MUST run through the encrypted tunnel. server's handshake) MUST run through the encrypted tunnel.
[RFC5246] [RFC5246]
2. Establish the following information: 2. Establish the following information:
/origin/ /origin/
The |Sec-WebSocket-Origin| header in the client's handshake The |Sec-WebSocket-Origin| header in the client's handshake
indicates the origin of the script establishing the indicates the origin of the script establishing the
connection. The origin is serialized to ASCII and converted connection. The origin is serialized to ASCII and converted
to lowercase. The server MAY use this information as part of to lowercase. The server MAY use this information as part of
a determination of whether to accept the incoming connection. a determination of whether to accept the incoming connection.
If the server does not validate the origin, it will accept If the server does not validate the origin, it will accept
connections from anywhere. For more detail, refer to connections from anywhere. If the server does not wish to
Section 9. accept this connection, it MUST return an appropriate HTTP
error code (e.g. 403 Forbidden) and abort the WebSocket
handshake described in this section. For more detail, refer
to Section 10.
/key/ /key/
The |Sec-WebSocket-Key| header in the client's handshake The |Sec-WebSocket-Key| header in the client's handshake
includes a base64-encoded value that, if decoded, is 16 bytes includes a base64-encoded value that, if decoded, is 16 bytes
in length. This (encoded) value is used in the creation of in length. This (encoded) value is used in the creation of
the server's handshake to indicate an acceptance of the the server's handshake to indicate an acceptance of the
connection. It is not necessary for the server to base64- connection. It is not necessary for the server to base64-
decode the Sec-WebSocket-Key value. decode the "Sec-WebSocket-Key" value.
/version/ /version/
The |Sec-WebSocket-Version| header in the client's handshake The |Sec-WebSocket-Version| header in the client's handshake
includes the version of the WebSocket protocol the client is includes the version of the WebSocket protocol the client is
attempting to communicate with. If this version does not attempting to communicate with. If this version does not
match a version understood by the server, the server MUST match a version understood by the server, the server MUST
abort the WebSocket connection. The server MAY send a non-200 abort the websocket handshake described in this section and
response code with a |Sec-WebSocket-Version| header indicating instead send an appropriate HTTP error code (such as 426
the version(s) the server is capable of understanding. Upgrade Required), and a |Sec-WebSocket-Version| header
indicating the version(s) the server is capable of
understanding.
/resource name/ /resource name/
An identifier for the service provided by the server. If the An identifier for the service provided by the server. If the
server provides multiple services, then the value should be server provides multiple services, then the value should be
derived from the resource name given in the client's handshake derived from the resource name given in the client's handshake
from the Request-URI [RFC2616] of the GET method. from the Request-URI [RFC2616] of the GET method. If the
requested service is not available, the server MUST send an
appropriate HTTP error code (such as 404 Not Found) and abort
the WebSocket handshake.
/subprotocol/ /subprotocol/
Either a single value or null, representing the subprotocol Either a single value or null, representing the subprotocol
the server is ready to use. If the server supports multiple the server is ready to use. If the server supports multiple
subprotocols, then the value MUST be derived from the client's subprotocols, then the value MUST be derived from the client's
handshake, specifically by selecting one of the values from handshake, specifically by selecting one of the values from
the "Sec-WebSocket-Protocol" field. The absence of such a the "Sec-WebSocket-Protocol" field. The absence of such a
field is equivalent to the null value. The empty string is field is equivalent to the null value. The empty string is
not the same as the null value for these purposes, and is not not the same as the null value for these purposes, and is not
a legal value for this field. The ABNF for the value of this a legal value for this field. The ABNF for the value of this
header is (token | quoted-string), where the definitions of header is (token), where the definitions of constructs and
constructs and rules are as given in [RFC2616]. rules are as given in [RFC2616].
/extensions/ /extensions/
A (possibly empty) list representing the protocol-level A (possibly empty) list representing the protocol-level
extensions the server is ready to use. If the server supports extensions the server is ready to use. If the server supports
multiple extensions, then the value MUST be derived from the multiple extensions, then the value MUST be derived from the
client's handshake, specifically by selecting one or more of client's handshake, specifically by selecting one or more of
the values from the "Sec-WebSocket-Extensions" field. The the values from the "Sec-WebSocket-Extensions" field. The
absence of such a field is equivalent to the null value. The absence of such a field is equivalent to the null value. The
empty string is not the same as the null value for these empty string is not the same as the null value for these
purposes. Extensions not listed by the client MUST NOT be purposes. Extensions not listed by the client MUST NOT be
listed. The method by which these values should be selected listed. The method by which these values should be selected
and interpreted is discussed in Section 8.1. and interpreted is discussed in Section 9.1.
3. If the server chooses to accept the incoming connection, it MUST 3. If the server chooses to accept the incoming connection, it MUST
reply with a valid HTTP response indicating the following. reply with a valid HTTP response indicating the following.
1. A 101 response code. Such a response could look like 1. A 101 response code. Such a response could look like
"HTTP/1.1 101 Switching Protocols" "HTTP/1.1 101 Switching Protocols"
2. A "Sec-WebSocket-Accept" header. The value of this header is 2. A "Sec-WebSocket-Accept" header. The value of this header is
constructed by concatenating /key/, defined above in constructed by concatenating /key/, defined above in
Paragraph 2 of Section 5.2.2, with the string "258EAFA5-E914- Paragraph 2 of Section 5.2.2, with the string "258EAFA5-E914-
47DA-95CA-C5AB0DC85B11", taking the SHA-1 hash of this 47DA-95CA-C5AB0DC85B11", taking the SHA-1 hash of this
concatenated value to obtain a 20-byte value, and base64- concatenated value to obtain a 20-byte value, and base64-
encoding this 20-byte hash. encoding this 20-byte hash.
The ABNF of this header is defined as follows:
accept-value = base64-value
base64-value = *base64-data [ base64-padding ]
base64-data = 4base64-character
base64-padding = (2base64-character "==") / (3base64-character "=")
base64-character = ALPHA / DIGIT / "+" / "/"
NOTE: As an example, if the value of the "Sec-WebSocket-Key" NOTE: As an example, if the value of the "Sec-WebSocket-Key"
header in the client's handshake were header in the client's handshake were
"dGhlIHNhbXBsZSBub25jZQ==", the server would append the "dGhlIHNhbXBsZSBub25jZQ==", the server would append the
string "258EAFA5-E914-47DA-95CA-C5AB0DC85B11" to form the string "258EAFA5-E914-47DA-95CA-C5AB0DC85B11" to form the
string "dGhlIHNhbXBsZSBub25jZQ==258EAFA5-E914-47DA-95CA- string "dGhlIHNhbXBsZSBub25jZQ==258EAFA5-E914-47DA-95CA-
C5AB0DC85B11". The server would then take the SHA-1 hash of C5AB0DC85B11". The server would then take the SHA-1 hash of
this string, giving the value 0xb3 0x7a 0x4f 0x2c 0xc0 0x62 this string, giving the value 0xb3 0x7a 0x4f 0x2c 0xc0 0x62
0x4f 0x16 0x90 0xf6 0x46 0x06 0xcf 0x38 0x59 0x45 0xb2 0xbe 0x4f 0x16 0x90 0xf6 0x46 0x06 0xcf 0x38 0x59 0x45 0xb2 0xbe
0xc4 0xea. This value is then base64-encoded, to give the 0xc4 0xea. This value is then base64-encoded, to give the
value "s3pPLMBiTxaQ9kYGzzhZRbK+xOo=", which would be returned value "s3pPLMBiTxaQ9kYGzzhZRbK+xOo=", which would be returned
in the "Sec-WebSocket-Accept" header. in the "Sec-WebSocket-Accept" header.
3. Optionally, a "Sec-WebSocket-Protocol" header, with a value 3. Optionally, a "Sec-WebSocket-Protocol" header, with a value
/subprotocol/ as defined in Paragraph 2 of Section 5.2.2. /subprotocol/ as defined in Paragraph 2 of Section 5.2.2.
4. Optionally, a "Sec-WebSocket-Extensions" header, with a value 4. Optionally, a "Sec-WebSocket-Extensions" header, with a value
/extensions/ as defined in Paragraph 2 of Section 5.2.2. /extensions/ as defined in Paragraph 2 of Section 5.2.2. If
multiple extensions are to be used, they must all be listed
in a single Sec-WebSocket-Extensions header. This header
MUST NOT be repeated.
This completes the server's handshake. If the server finishes these This completes the server's handshake. If the server finishes these
steps without aborting the WebSocket connection, and if the client steps without aborting the WebSocket handshake, the server considers
does not then fail the WebSocket connection, then the connection is the WebSocket connection to be established and that the WebSocket
established and the server may begin sending and receiving data. connection is in the OPEN state. At this point, the server may begin
sending (and receiving) data.
6. Error Handling 6. Sending and Receiving Data
6.1. Handling errors in UTF-8 from the server 6.1. Sending Data
When a client is to interpret a byte stream as UTF-8 but finds that To _Send a WebSocket Message_ comprising of /data/ over a WebSocket
the byte stream is not in fact a valid UTF-8 stream, then any bytes connection, an endpoint MUST perform the following steps.
or sequences of bytes that are not valid UTF-8 sequences MUST be
interpreted as a U+FFFD REPLACEMENT CHARACTER.
6.2. Handling errors in UTF-8 from the client 1. The endpoint MUST ensure the WebSocket connection is in the OPEN
state (cf. Section 5.1 and Section 5.2.2.) If at any point the
state of the WebSocket connection changes, the endpoint MUST
abort the following steps.
When a server is to interpret a byte stream as UTF-8 but finds that 2. An endpoint MUST encapsulate the /data/ in a WebSocket frame as
the byte stream is not in fact a valid UTF-8 stream, behavior is defined in Section 4.2. If the data to be sent is large, or if
undefined. A server could close the connection, convert invalid byte the data is not available in its entirety at the point the
sequences to U+FFFD REPLACEMENT CHARACTERs, store the data verbatim, endpoint wishes to begin sending the data, the endpoint MAY
or perform application-specific processing. Subprotocols layered on alternately encapsulate the data in a series of frames as defined
the WebSocket protocol might define specific behavior for servers. in Section 4.4.
3. The opcode (frame-opcode) of the first frame containing the data
MUST be set to the appropriate value from Section 4.2 for data
that is to be interpreted by the recipient as text or binary
data.
4. The FIN bit (frame-fin) of the last frame containing the data
MUST be set to 1 as defined in Section 4.2.
5. If the data is being sent by the client, the frame(s) MUST be
masked as defined in Section 4.3.
6. If any extensions (Section 9) have been negotiated for the
WebSocket connection, additional considerations may apply as per
the definition of those extensions.
7. The frame(s) that have been formed MUST be transmitted over the
underlying network connection.
6.2. Receiving Data
To receive WebSocket data, an endpoint listens on the underlying
network connection. Incoming data MUST be parsed as WebSocket frames
as defined in Section 4.2. If a control frame (Section 4.5) is
received, the frame MUST be handled as defined by Section 4.5. Upon
receiving a data frame (Section 4.6), the endpoint MUST note the
/type/ of the data as defined by the Opcode (frame-opcode) from
Section 4.2. The _Application Data_ from this frame is defined as
the /data/ of the message. If the frame comprises an unfragmented
message (Section 4.4), it is said that _A WebSocket Message Has Been
Received_ with type /type/ and data /data/. If the frame is part of
a fragmented message, the _Application Data_ of the subsequent data
frames is concatenated to form the /data/. When the last fragment is
received as indicated by the FIN bit (frame-fin), it is said that _A
WebSocket Message Has Been Received_ with data /data/ (comprised of
the concatenation of the _Application Data_ of the fragments) and
type /type/ (noted from the first frame of the fragmented message).
Subsequent data frames MUST be interpreted as belonging to a new
WebSocket Message.
Extensions (Section 9) MAY change the semantics of how data is read,
specifically including what comprises a message boundary.
Data frames received by a server from a client MUST be unmasked as
described in Section 4.3.
7. Closing the connection 7. Closing the connection
7.1. Definitions 7.1. Definitions
7.1.1. Close the WebSocket Connection 7.1.1. Close the WebSocket Connection
To _Close the WebSocket Connection_, an endpoint closes the To _Close the WebSocket Connection_, an endpoint closes the
underlying TCP connection. An endpoint SHOULD use a method that underlying TCP connection. An endpoint SHOULD use a method that
cleanly closes the TCP connection, as well as the TLS session, if cleanly closes the TCP connection, as well as the TLS session, if
applicable, discarding any trailing bytes that may be received. An applicable, discarding any trailing bytes that may be received. An
endpoint MAY close the connection via any means available when endpoint MAY close the connection via any means available when
necessary, such as when under attack. necessary, such as when under attack.
The underlying TCP connection, in most normal cases, SHOULD be closed
first by the server, so that it holds the TIME_WAIT state and not the
client (as this would prevent it from re-opening the connection for 2
MSL, while there is no corresponding server impact as a TIME_WAIT
connection is immediately reopened upon a new SYN with a higher seq
number). In abnormal cases (such as not having received a TCP Close
from the server after a reasonable amount of time) a client MAY
initiate the TCP Close. As such, when a server is instructed to
_Close the WebSocket Connection_ it SHOULD initiate a TCP Close
immediately, and when a client is instructed to do the same, it
SHOULD wait for a TCP Close from the server.
As an example of how to obtain a clean closure in C using Berkeley As an example of how to obtain a clean closure in C using Berkeley
sockets, one would call shutdown() with SHUT_WR on the socket, call sockets, one would call shutdown() with SHUT_WR on the socket, call
recv() until obtaining a return value of 0 indicating that the peer recv() until obtaining a return value of 0 indicating that the peer
has also performed an orderly shutdown, and finally calling close() has also performed an orderly shutdown, and finally calling close()
on the socket. on the socket.
7.1.2. Start the WebSocket Closing Handshake 7.1.2. Start the WebSocket Closing Handshake
To _start the WebSocket closing handshake_, an endpoint MUST send a To _Start the WebSocket Closing Handshake_ with a status code
Close control frame, as described in Section 4.5.1. Once an endpoint (Section 7.4) /code/ and an optional close reason (Section 7.1.6)
has both sent and received a Close control frame, that endpoint /reason/, an endpoint MUST send a Close control frame, as described
SHOULD _Close the WebSocket Connection_ as defined in Section 7.1.1. in Section 4.5.1 whose status code is set to /code/ and whose close
reason is set to /reason/. Once an endpoint has both sent and
received a Close control frame, that endpoint SHOULD _Close the
WebSocket Connection_ as defined in Section 7.1.1.
7.1.3. The WebSocket Connection Is Closed 7.1.3. The WebSocket Closing Handshake is Started
When the underlying TCP connection is closed, it is said that _the Upon either sending or receiving a Close control frame, it is said
WebSocket connection is closed_. If the tcp connection was closed that _The WebSocket Closing Handshake is Started_ and that the
after the WebSocket closing handshake was completed, the WebSocket WebSocket connection is in the CLOSING state.
connection is said to have been closed _cleanly_.
7.1.4. Fail the WebSocket Connection 7.1.4. The WebSocket Connection is Closed
Certain algorithms and specifications require a user agent to _fail When the underlying TCP connection is closed, it is said that _The
the WebSocket connection_. To do so, the user agent MUST _Close the WebSocket Connection is Closed_ and that the WebSocket connection is
in the CLOSED state. If the tcp connection was closed after the
WebSocket closing handshake was completed, the WebSocket connection
is said to have been closed _cleanly_.
If the WebSocket connection could not be established, it is also said
that _The WebSocket Connection is Closed_, but not cleanly.
7.1.5. The WebSocket Connection Close Code
As defined in Section 4.5.1 and Section 7.4, a Close control frame
may contain a status code indicating a reason for closure. A closing
of the WebSocket connection may be initiated by either endpoint,
potentially simultaneously. _The WebSocket Connection Close Code_ is
defined as the status code (Section 7.4) contained in the first Close
control frame received by the application implementing this protocol.
If this Close control frame contains no status code, _The WebSocket
Connection Close Code_ is considered to be 1005. If _The WebSocket
Connection is Closed_ and no Close control frame was received by the
endpoint (such as could occur if the underlying transport connection
is lost), _The WebSocket Connection Close Code_ is considered to be
1006.
NOTE: Two endpoints may not agree on the value of _The WebSocket
Connection Close Code_. As an example, if the remote endpoint sent a
Close frame but the local application has not yet read the data
containing the Close frame from its socket's receive buffer, and the
local application independently decided to close the connection and
send a Close frame, both endpoints will have sent and received a
Close frame, and will not send further Close frames. Each endpoint
will see the Connection Close Code sent by the other end as the
_WebSocket Connection Close Code_. As such, it is possible that the
two endpoints may not agree on the value of _The WebSocket Connection
Close Code_ in the case that both endpoints _Start the WebSocket
Closing Handshake_ independently and at roughly the same time.
7.1.6. The WebSocket Connection Close Reason
As defined in Section 4.5.1 and Section 7.4, a Close control frame
may contain a status code indicating a reason for closure, followed
by UTF-8 encoded data, the interpretation of said data being left to
the endpoints and not defined by this protocol. A closing of the
WebSocket connection may be initiated by either endpoint, potentially
simultaneously. _The WebSocket Connection Close Reason_ is defined as
the UTF-8 encoded data following the status code (Section 7.4)
contained in the first Close control frame received by the
application implementing this protocol. If there is no such data in
the Close control frame, _The WebSocket Connection Close Reason_ is
the empty string.
NOTE: Following the same logic as noted in Section 7.1.5, two
endpoints may not agree on _The WebSocket Connection Close Reason_.
7.1.7. Fail the WebSocket Connection
Certain algorithms and specifications require an endpoint to _Fail
the WebSocket Connection_. To do so, the client MUST _Close the
WebSocket Connection_, and MAY report the problem to the user (which WebSocket Connection_, and MAY report the problem to the user (which
would be especially useful for developers) in an appropriate manner. would be especially useful for developers) in an appropriate manner.
If _The WebSocket Connection is Established_ prior to the point where
the endpoint is required to _Fail the WebSocket Connection_, the
endpoint SHOULD send a Close frame with an appropriate status code
Section 7.4 before proceeding to _Close the WebSocket Connection_.
An endpoint MAY omit sending a Close frame if it believes the other
side is unlikely to be able to receive and process the close frame,
due to the nature of the error that led to the WebSocket connection
being failed in the first place. An endpoint MUST NOT continue to
attempt to process data (including a responding Close frame) from the
remote endpoint after being instruted to _Fail the WebSocket
Connection_.
Except as indicated above or as specified by the application layer Except as indicated above or as specified by the application layer
(e.g. a script using the WebSocket API), user agents SHOULD NOT close (e.g. a script using the WebSocket API), clients SHOULD NOT close the
the connection. connection.
7.2. Abnormal closures 7.2. Abnormal Closures
7.2.1. Client-initiated closure
Certain algorithms, namely during the initial handshake, require the 7.2.1. Client-Initiated Closure
user agent to *fail the WebSocket connection*. To do so, the user
agent MUST _Close the WebSocket connection_ as previously defined, Certain algorithms, namely during the opening handshake, require the
and MAY report the problem to the user via an appropriate mechanism client to _Fail the WebSocket Connection_. To do so, the client MUST
(which would be especially useful for developers). _Fail the WebSocket Connection_ as defined in Section 7.1.7.
If at any point the underlying transport layer connection is
unexpectedly lost, the client MUST _Fail the WebSocket Connection_.
Except as indicated above or as specified by the application layer Except as indicated above or as specified by the application layer
(e.g. a script using the WebSocket API), user agents SHOULD NOT close (e.g. a script using the WebSocket API), clients SHOULD NOT close the
the connection. connection.
7.2.2. Server-initiated closure 7.2.2. Server-initiated closure
Certain algorithms require or recommend that the server _abort the Certain algorithms require or recommend that the server _Abort the
WebSocket connection_ during the opening handshake. To do so, the WebSocket Connection_ during the opening handshake. To do so, the
server MUST simply _close the WebSocket connection_ (Section 7.1.1). server MUST simply _Close the WebSocket Connection_ (Section 7.1.1).
7.3. Normal closure of connections 7.3. Normal Closure of Connections
Servers MAY close the WebSocket connection whenever desired. User Servers MAY close the WebSocket connection whenever desired. Clients
agents SHOULD NOT close the WebSocket connection arbitrarily. In SHOULD NOT close the WebSocket connection arbitrarily. In either
either case, an endpoint initiates a closure by following the case, an endpoint initiates a closure by following the procedures to
procedures to _start the WebSocket closing handshake_ _Start the WebSocket Closing Handshake_ (Section 7.1.2).
(Section 7.1.2).
7.4. Status codes 7.4. Status Codes
When closing an established connection (e.g. when sending a Close When closing an established connection (e.g. when sending a Close
frame, after the handshake has completed), an endpoint MAY indicate a frame, after the opening handshake has completed), an endpoint MAY
reason for closure. The interpretation of this reason by an indicate a reason for closure. The interpretation of this reason by
endpoint, and the action an endpoint should take given this reason, an endpoint, and the action an endpoint should take given this
are left undefined by this specification. This specification defines reason, are left undefined by this specification. This specification
a set of pre-defined status codes, and specifies which ranges may be defines a set of pre-defined status codes, and specifies which ranges
used by extensions, frameworks, and end applications. The status may be used by extensions, frameworks, and end applications. The
code and any associated textual message are optional components of a status code and any associated textual message are optional
Close frame. components of a Close frame.
7.4.1. Defined Status Codes 7.4.1. Defined Status Codes
Endpoints MAY use the following pre-defined status codes when sending Endpoints MAY use the following pre-defined status codes when sending
a Close frame. a Close frame.
1000 1000
1000 indicates a normal closure, meaning whatever purpose the 1000 indicates a normal closure, meaning whatever purpose the
connection was established for has been fulfilled. connection was established for has been fulfilled.
skipping to change at page 39, line 25 skipping to change at page 43, line 15
1003 1003
1003 indicates that an endpoint is terminating the connection 1003 indicates that an endpoint is terminating the connection
because it has received a type of data it cannot accept (e.g. an because it has received a type of data it cannot accept (e.g. an
endpoint that understands only text data MAY send this if it endpoint that understands only text data MAY send this if it
receives a binary message). receives a binary message).
1004 1004
1004 indicates that an endpoint is terminating the connection 1004 indicates that an endpoint is terminating the connection
because it has received a message that is too large. because it has received a frame that is too large.
7.4.2. Reserved status code ranges 1005
1005 is a reserved value and MUST NOT be set as a status code in a
Close control frame by an endpoint. It is designated for use in
applications expecting a status code to indicate that no status
code was actually present.
1006
1006 is a reserved value and MUST NOT be set as a status code in a
Close control frame by an endpoint. It is designated for use in
applications expecting a status code to indicate that the
connection was closed abnormally, e.g. without sending or
receiving a Close control frame.
7.4.2. Reserved Status Code Ranges
0-999 0-999
Status codes in the range 0-999 are not used. Status codes in the range 0-999 are not used.
1000-1999 1000-1999
Status codes in the range 1000-1999 are reserved for definition by Status codes in the range 1000-1999 are reserved for definition by
this protocol. this protocol.
skipping to change at page 41, line 5 skipping to change at page 45, line 5
frameworks. The interpretation of these codes is undefined by frameworks. The interpretation of these codes is undefined by
this protocol. End applications MUST NOT use status codes in this this protocol. End applications MUST NOT use status codes in this
range. range.
4000-4999 4000-4999
Status codes in the range 4000-4999 MAY be used by application Status codes in the range 4000-4999 MAY be used by application
code. The interpretation of these codes is undefined by this code. The interpretation of these codes is undefined by this
protocol. protocol.
8. Extensions 8. Error Handling
8.1. Handling Errors in UTF-8 from the Server
When a client is to interpret a byte stream as UTF-8 but finds that
the byte stream is not in fact a valid UTF-8 stream, then any bytes
or sequences of bytes that are not valid UTF-8 sequences MUST be
interpreted as a U+FFFD REPLACEMENT CHARACTER.
8.2. Handling Errors in UTF-8 from the Client
When a server is to interpret a byte stream as UTF-8 but finds that
the byte stream is not in fact a valid UTF-8 stream, behavior is
undefined. A server could close the connection, convert invalid byte
sequences to U+FFFD REPLACEMENT CHARACTERs, store the data verbatim,
or perform application-specific processing. Subprotocols layered on
the WebSocket protocol might define specific behavior for servers.
9. Extensions
WebSocket clients MAY request extensions to this specification, and WebSocket clients MAY request extensions to this specification, and
WebSocket servers MAY accept some or all extensions requested by the WebSocket servers MAY accept some or all extensions requested by the
client. A server MUST NOT respond with any extension not requested client. A server MUST NOT respond with any extension not requested
by the client. If extension parameters are included in negotiations by the client. If extension parameters are included in negotiations
between the client and the server, those parameters MUST be chosen in between the client and the server, those parameters MUST be chosen in
accordance with the specification of the extension to which the accordance with the specification of the extension to which the
parameters apply. parameters apply.
8.1. Negotiating extensions 9.1. Negotiating Extensions
A client requests extensions by including a "Sec-WebSocket- A client requests extensions by including a "Sec-WebSocket-
Extensions" header, which follows the normal rules for HTTP headers Extensions" header, which follows the normal rules for HTTP headers
(see [RFC2616] section 4.2) and the value of the header is defined by (see [RFC2616] section 4.2) and the value of the header is defined by
the following ABNF. Note that unlike other section of the document the following ABNF. Note that unlike other section of the document
this section is using ABNF syntax/rules from [RFC2616]. this section is using ABNF syntax/rules from [RFC2616]. If a value
is received by either the client or the server during negotiation
that does not conform to the ABNF below, the recipient of such
malformed data MUST immediately _Fail the WebSocket Connection_.
extension-list = 1#extension extension-list = 1#extension
extension = extension-token *( ";" extension-param ) extension = extension-token *( ";" extension-param )
extension-token = registered-token | private-use-token extension-token = registered-token / private-use-token
registered-token = token registered-token = token
private-use-token = "x-" token private-use-token = "x-" token
extension-param = token [ "=" ( token | quoted-string ) ] extension-param = token [ "=" token ]
Note that like other HTTP headers, this header MAY be split or Note that like other HTTP headers, this header MAY be split or
combined across multiple lines. Ergo, the following are equivalent: combined across multiple lines. Ergo, the following are equivalent:
Sec-WebSocket-Extensions: foo Sec-WebSocket-Extensions: foo
Sec-WebSocket-Extensions: bar; baz=2 Sec-WebSocket-Extensions: bar; baz=2
is exactly equivalent to is exactly equivalent to
Sec-WebSocket-Extensions: foo, bar; baz=2 Sec-WebSocket-Extensions: foo, bar; baz=2
skipping to change at page 42, line 29 skipping to change at page 47, line 32
Sec-WebSocket-Extensions: mux; max-channels=4; flow-control, deflate-stream Sec-WebSocket-Extensions: mux; max-channels=4; flow-control, deflate-stream
Sec-WebSocket-Extensions: x-private-extension Sec-WebSocket-Extensions: x-private-extension
A server accepts one or more extensions by including a |Sec- A server accepts one or more extensions by including a |Sec-
WebSocket-Extensions| header containing one or more extensions which WebSocket-Extensions| header containing one or more extensions which
were requested by the client. The interpretation of any extension were requested by the client. The interpretation of any extension
parameters, and what constitutes a valid response by a server to a parameters, and what constitutes a valid response by a server to a
requested set of parameters by a client, will be defined by each such requested set of parameters by a client, will be defined by each such
extension. extension.
8.2. Known extensions 9.2. Known Extensions
Extensions provide a mechanism for implementations to opt-in to Extensions provide a mechanism for implementations to opt-in to
additional protocol features. This section defines the meaning of additional protocol features. This section defines the meaning of
well-known extensions but implementations MAY use extensions defined well-known extensions but implementations MAY use extensions defined
separately as well. separately as well.
8.2.1. Compression 9.2.1. Compression
The registered extension token for this compression extension is The registered extension token for this compression extension is
"deflate-stream". "deflate-stream".
The extension does not have any per message extension data and it The extension does not have any per frame extension data and it does
does not define the use of any WebSocket reserved bits or op codes. not define the use of any WebSocket reserved bits or op codes.
Senders using this extension MUST apply RFC 1951 encodings to all Senders using this extension MUST apply [RFC1951] encodings to all
bytes of the data stream following the handshake including both data bytes of the data stream following the opening handshake including
and control messages. The data stream MAY include multiple blocks of both data and control frames. The data stream MAY include multiple
both compressed and uncompressed types as defined by [RFC1951]. blocks of both compressed and uncompressed types as defined by
[RFC1951].
Senders MUST NOT delay the transmission of any portion of a WebSocket Senders MUST NOT delay the transmission of any portion of a WebSocket
message because the deflate encoding of the message does not end on a frame because the deflate encoding of the frame does not end on a
byte boundary. The encodings for adjacent messages MAY appear in the byte boundary. The encodings for adjacent frames MAY appear in the
same byte if no delay in transmission is occurred by doing so. same byte if no delay in transmission is occurred by doing so.
Historically there have been some confusion and interoperability Historically there have been some confusion and interoperability
problems around the specification of compression algorithms. In this problems around the specification of compression algorithms. In this
specification "deflate-stream" requires a [RFC1951] deflate encoding. specification "deflate-stream" requires a [RFC1951] deflate encoding.
It MUST NOT be wrapped in any of the header formats often associated It MUST NOT be wrapped in any of the header formats often associated
with RFC 1951 such as "zlib" [RFC1950]. This requirement is given with RFC 1951 such as "zlib" [RFC1950]. This requirement is given
special attention with this note because of confusion in this area, special attention with this note because of confusion in this area,
the presence of some popular open source libraries that create both the presence of some popular open source libraries that create both
formats under a single API call with confusing naming conventions, formats under a single API call with confusing naming conventions,
and the fact that the popular HTTP [RFC2616] specification defines and the fact that the popular HTTP [RFC2616] specification defines
"deflate" compression differently than this specification. "deflate" compression differently than this specification.
9. Security considerations 10. Security Considerations
While this protocol is intended to be used by scripts in Web pages, While this protocol is intended to be used by scripts in Web pages,
it can also be used directly by hosts. Such hosts are acting on it can also be used directly by hosts. Such hosts are acting on
their own behalf, and can therefore send fake "Origin" fields, their own behalf, and can therefore send fake "Origin" fields,
misleading the server. Servers should therefore be careful about misleading the server. Servers should therefore be careful about
assuming that they are talking directly to scripts from known assuming that they are talking directly to scripts from known
origins, and must consider that they might be accessed in unexpected origins, and must consider that they might be accessed in unexpected
ways. In particular, a server should not trust that any input is ways. In particular, a server should not trust that any input is
valid. valid.
skipping to change at page 44, line 30 skipping to change at page 49, line 30
Servers that are not intended to process input from any Web page but Servers that are not intended to process input from any Web page but
only for certain sites SHOULD verify the "Origin" field is an origin only for certain sites SHOULD verify the "Origin" field is an origin
they expect, and should only respond with the corresponding "Sec- they expect, and should only respond with the corresponding "Sec-
WebSocket-Origin" if it is an accepted origin. Servers that only WebSocket-Origin" if it is an accepted origin. Servers that only
accept input from one origin can just send back that value in the accept input from one origin can just send back that value in the
"Sec-WebSocket-Origin" field, without bothering to check the client's "Sec-WebSocket-Origin" field, without bothering to check the client's
value. value.
If at any time a server is faced with data that it does not If at any time a server is faced with data that it does not
understand, or that violates some criteria by which the server understand, or that violates some criteria by which the server
determines safety of input, or when the server sees a handshake that determines safety of input, or when the server sees an opening
does not correspond to the values the server is expecting (e.g. handshake that does not correspond to the values the server is
incorrect path or origin), the server SHOULD just disconnect. It is expecting (e.g. incorrect path or origin), the server SHOULD just
always safe to disconnect. disconnect. It is always safe to disconnect.
The biggest security risk when sending text data using this protocol The biggest security risk when sending text data using this protocol
is sending data using the wrong encoding. If an attacker can trick is sending data using the wrong encoding. If an attacker can trick
the server into sending data encoded as ISO-8859-1 verbatim (for the server into sending data encoded as ISO-8859-1 verbatim (for
instance), rather than encoded as UTF-8, then the attacker could instance), rather than encoded as UTF-8, then the attacker could
inject arbitrary frames into the data stream. inject arbitrary frames into the data stream.
In addition to endpoints being the target of attacks via WebSockets, In addition to endpoints being the target of attacks via WebSockets,
other parts of web infrastructure, such as proxies, may be the other parts of web infrastructure, such as proxies, may be the
subject of an attack. In particular, an intermediary may interpret a subject of an attack. In particular, an intermediary may interpret a
WebSocket message from a client as a request, and a message from the WebSocket frame from a client as a request, and a frame from the
server as a response to that request. For instance, an attacker server as a response to that request. For instance, an attacker
could get a browser to establish a connection to its server, get the could get a browser to establish a connection to its server, get the
browser to send a message that looks to an intermediary like a GET browser to send a frame that looks to an intermediary like a GET
request for a common piece of JavaScript on another domain, and send request for a common piece of JavaScript on another domain, and send
back a message that is interpreted as a cacheable response to that back a frame that is interpreted as a cacheable response to that
request, thus poisioning the cache for other users. To prevent this request, thus poisioning the cache for other users. To prevent this
attack, messages sent from clients are masked on the wire with a 32- attack, frames sent from clients are masked on the wire with a 32-bit
bit value, to prevent an attacker from controlling the bits on the value, to prevent an attacker from controlling the bits on the wire
wire and thus lessen the probability of an attacker being able to and thus lessen the probability of an attacker being able to
construct a message that can be misinterpreted by a proxy as a non- construct a frame that can be misinterpreted by a proxy as a non-
WebSocket request. WebSocket request.
As mentioned in Section 6.2, servers must be extremely cautious As mentioned in Section 8.2, servers must be extremely cautious
interpreting invalid UTF-8 data from the client. A naive UTF-8 interpreting invalid UTF-8 data from the client. A naive UTF-8
parsing implementation can result in buffer overflows in the case of parsing implementation can result in buffer overflows in the case of
invalid input data. invalid input data.
10. IANA considerations For connections using TLS (wss: URIs), the amount of benefit provided
by TLS depends greatly on the strength of the algorithms negotiated
during the TLS handshake. To achieve reasonable levels of
protections, clients should use only Strong TLS algorithms. "Web
Security Context: User Interface Guidelines"
[W3C.REC-wsc-ui-20100812] discusses what constitutes Strong TLS
algorithms.
10.1. Registration of ws: scheme 11. IANA Considerations
11.1. Registration of "ws:" Scheme
A |ws:| URI identifies a WebSocket server and resource name. A |ws:| URI identifies a WebSocket server and resource name.
URI scheme name. URI scheme name.
ws ws
Status. Status.
Permanent. Permanent.
URI scheme syntax. URI scheme syntax.
skipping to change at page 47, line 17 skipping to change at page 52, line 17
Contact. Contact.
HYBI WG <hybi@ietf.org> HYBI WG <hybi@ietf.org>
Author/Change controller. Author/Change controller.
IETF <iesg@ietf.org> IETF <iesg@ietf.org>
References. References.
RFC XXXX RFC XXXX
10.2. Registration of wss: scheme 11.2. Registration of "wss:" Scheme
A |wss:| URI identifies a WebSocket server and resource name, and A |wss:| URI identifies a WebSocket server and resource name, and
indicates that traffic over that connection is to be encrypted. indicates that traffic over that connection is to be protected via
TLS (including standard benefits of TLS such as confidentiality,
integrity, and authentication).
URI scheme name. URI scheme name.
wss wss
Status. Status.
Permanent. Permanent.
URI scheme syntax. URI scheme syntax.
In ABNF terms using the terminals from the URI specifications: In ABNF terms using the terminals from the URI specifications:
[RFC5234] [RFC3986] [RFC5234] [RFC3986]
skipping to change at page 48, line 24 skipping to change at page 53, line 26
Contact. Contact.
HYBI WG <hybi@ietf.org> HYBI WG <hybi@ietf.org>
Author/Change controller. Author/Change controller.
IETF <iesg@ietf.org> IETF <iesg@ietf.org>
References. References.
RFC XXXX RFC XXXX
10.3. Registration of the "WebSocket" HTTP Upgrade keyword 11.3. Registration of the "WebSocket" HTTP Upgrade Keyword
This section defines a keyword for registration in the "HTTP Upgrade
Tokens" registry as per RFC 2817 [RFC2817].
Name of token. Name of token.
WebSocket WebSocket
Author/Change controller. Author/Change controller.
IETF <iesg@ietf.org> IETF <iesg@ietf.org>
Contact. Contact.
HYBI <hybi@ietf.org> HYBI <hybi@ietf.org>
References. References.
RFC XXXX RFC XXXX
10.4. Sec-WebSocket-Key 11.4. Sec-WebSocket-Key
This section describes a header field for registration in the This section describes a header field for registration in the
Permanent Message Header Field Registry. [RFC3864] Permanent Message Header Field Registry. [RFC3864]
Header field name Header field name
Sec-WebSocket-Key Sec-WebSocket-Key
Applicable protocol Applicable protocol
http http
Status Status
standard standard
Author/Change controller Author/Change controller
skipping to change at page 49, line 15 skipping to change at page 54, line 20
Status Status
standard standard
Author/Change controller Author/Change controller
IETF IETF
Specification document(s) Specification document(s)
RFC XXXX RFC XXXX
Related information Related information
This header field is only used for WebSocket handshake. This header field is only used for WebSocket opening handshake.
The |Sec-WebSocket-Key| header is used in the WebSocket handshake. The |Sec-WebSocket-Key| header is used in the WebSocket opening
It is sent from the client to the server to provide part of the handshake. It is sent from the client to the server to provide part
information used by the server to prove that it received a valid of the information used by the server to prove that it received a
WebSocket handshake. This helps ensure that the server does not valid WebSocket opening handshake. This helps ensure that the server
accept connections from non-WebSocket clients (e.g. HTTP clients) does not accept connections from non-WebSocket clients (e.g. HTTP
that are being abused to send data to unsuspecting WebSocket servers. clients) that are being abused to send data to unsuspecting WebSocket
servers.
10.5. Sec-WebSocket-Extensions 11.5. Sec-WebSocket-Extensions
This section describes a header field for registration in the This section describes a header field for registration in the
Permanent Message Header Field Registry. [RFC3864] Permanent Message Header Field Registry. [RFC3864]
Header field name Header field name
Sec-WebSocket-Extensions Sec-WebSocket-Extensions
Applicable protocol Applicable protocol
http http
Status Status
standard standard
Author/Change controller Author/Change controller
IETF IETF
Specification document(s) Specification document(s)
RFC XXXX RFC XXXX
Related information Related information
This header field is only used for WebSocket handshake. This header field is only used for WebSocket opening handshake.
The |Sec-WebSocket-Extensions| header is used in the WebSocket The |Sec-WebSocket-Extensions| header is used in the WebSocket
handshake. It is initially sent from the client to the server, and opening handshake. It is initially sent from the client to the
then subsequently sent from the server to the client, to agree on a server, and then subsequently sent from the server to the client, to
set of protocol-level extensions to use for the duration of the agree on a set of protocol-level extensions to use for the duration
connection. of the connection.
10.6. Sec-WebSocket-Accept 11.6. WebSocket Extension Name Registry
This specification requests the creation of a new IANA registry for
WebSocket Extension names to be used with the WebSocket protocol in
accordance with the principles set out in RFC 5226 [RFC5226].
As part of this registry IANA will maintain the following
information:
Extension Identifier
The identifier of the extension, as will be used in the Sec-
WebSocket-Extension header registered in Section 11.5 of this
specification. The value must conform to the requirements for an
extension-token as defined in Section 9.1 of this specification.
Extension Common Name
The name of the extension, as the extension is generally referred
to.
Extension Definition
A reference to the document in which the extension being used with
the WebSocket protocol is defined.
Known Incompatible Extensions
A list of extension identifiers with which this extension is known
to be incompatible.
WebSocket Extension names are to be subject to First Come First Serve
as per RFC5226 [RFC5226], with the exception of WebSocket Extension
names whose Extension Identifier matches a private-use-token as
defined in Section 9.1 (values beginning with "x-"). These Extension
Identifiers matching private-use-token are reserved for Experimental
Use as per RFC5226 [RFC5226].
IANA is asked to add an initial value to the registry (there are no
known incompatible extensions for this initial entry):
Extension Identifier | Extension Common Name | Extension Definition
-+---------------------+------------------------+-----------------------
| deflate-stream | Deflate Stream | Section 9.2.1 of this
| | Compression | document.
-+---------------------+------------------------+-----------------------
11.7. Sec-WebSocket-Accept
This section describes a header field for registration in the This section describes a header field for registration in the
Permanent Message Header Field Registry. [RFC3864] Permanent Message Header Field Registry. [RFC3864]
Header field name Header field name
Sec-WebSocket-Accept Sec-WebSocket-Accept
Applicable protocol Applicable protocol
http http
Status Status
standard standard
Author/Change controller Author/Change controller
IETF IETF
Specification document(s) Specification document(s)
RFC XXXX RFC XXXX
Related information Related information
This header field is only used for WebSocket handshake. This header field is only used for WebSocket opening handshake.
The |Sec-WebSocket-Accept| header is used in the WebSocket handshake. The |Sec-WebSocket-Accept| header is used in the WebSocket opening
It is sent from the server to the client to confirm that the server handshake. It is sent from the server to the client to confirm that
is willing to initiate the connection. the server is willing to initiate the connection.
10.7. Sec-WebSocket-Origin 11.8. Sec-WebSocket-Origin
This section describes a header field for registration in the This section describes a header field for registration in the
Permanent Message Header Field Registry. [RFC3864] Permanent Message Header Field Registry. [RFC3864]
Header field name Header field name
Sec-WebSocket-Origin Sec-WebSocket-Origin
Applicable protocol Applicable protocol
http http
Status Status
standard standard
Author/Change controller Author/Change controller
IETF IETF
Specification document(s) Specification document(s)
RFC XXXX RFC XXXX
Related information Related information
This header field is only used for WebSocket handshake. This header field is only used for WebSocket opening handshake.
The |Sec-WebSocket-Origin| header is used in the WebSocket handshake. The |Sec-WebSocket-Origin| header is used in the WebSocket opening
It is sent from the server to the client to confirm the origin of the handshake. It is sent from the server to the client to confirm the
script that opened the connection. This enables user agents to origin of the script that opened the connection. This enables
verify that the server is willing to serve the script that opened the clients to verify that the server is willing to serve the script that
connection. opened the connection.
10.8. Sec-WebSocket-Protocol 11.9. Sec-WebSocket-Protocol
This section describes a header field for registration in the This section describes a header field for registration in the
Permanent Message Header Field Registry. [RFC3864] Permanent Message Header Field Registry. [RFC3864]
Header field name Header field name
Sec-WebSocket-Protocol Sec-WebSocket-Protocol
Applicable protocol Applicable protocol
http http
Status Status
standard standard
Author/Change controller Author/Change controller
IETF IETF
Specification document(s) Specification document(s)
RFC XXXX RFC XXXX
Related information Related information
This header field is only used for WebSocket handshake. This header field is only used for WebSocket opening handshake.
The |Sec-WebSocket-Protocol| header is used in the WebSocket The |Sec-WebSocket-Protocol| header is used in the WebSocket opening
handshake. It is sent from the client to the server and back from handshake. It is sent from the client to the server and back from
the server to the client to confirm the subprotocol of the the server to the client to confirm the subprotocol of the
connection. This enables scripts to both select a subprotocol and be connection. This enables scripts to both select a subprotocol and be
sure that the server agreed to serve that subprotocol. sure that the server agreed to serve that subprotocol.
10.9. Sec-WebSocket-Version 11.10. WebSocket Subprotocol Name Registry
This specification requests the creation of a new IANA registry for
WebSocket Subprotocol names to be used with the WebSocket protocol in
accordance with the principles set out in RFC 5226 [RFC5226].
As part of this registry IANA will maintain the following
information:
Subprotocol Identifier
The identifier of the subprotocol, as will be used in the Sec-
WebSocket-Protocol header registered in Section 11.9 of this
specification. The value must conform to the requirements given
in Paragraph 10 of Paragraph 4 of Section 5.1 of this
specification, namely the value must be a token as defined by RFC
2616 [RFC2616].
Subprotocol Common Name
The name of the subprotocol, as the subprotocol is generally
referred to.
Subprotocol Definition
A reference to the document in which the subprotocol being used
with the WebSocket protocol is defined.
WebSocket Subprotocol names are to be subject to First Come First
Serve as per RFC5226 [RFC5226].
11.11. Sec-WebSocket-Version
This section describes a header field for registration in the This section describes a header field for registration in the
Permanent Message Header Field Registry. [RFC3864] Permanent Message Header Field Registry. [RFC3864]
Header field name Header field name
Sec-WebSocket-Version Sec-WebSocket-Version
Applicable protocol Applicable protocol
http http
Status Status
standard standard
Author/Change controller Author/Change controller
IETF IETF
Specification document(s) Specification document(s)
RFC XXXX RFC XXXX
Related information Related information
This header field is only used for WebSocket handshake. This header field is only used for WebSocket opening handshake.
The |Sec-WebSocket-Version| header is used in the WebSocket The |Sec-WebSocket-Version| header is used in the WebSocket opening
handshake. It is sent from the client to the server to indicate the handshake. It is sent from the client to the server to indicate the
protocol version of the connection. This enables servers to protocol version of the connection. This enables servers to
correctly interpret the handshake and subsequent data being sent from correctly interpret the opening handshake and subsequent data being
the data, and close the connection if the server cannot interpret sent from the data, and close the connection if the server cannot
that data in a safe manner. interpret that data in a safe manner.
11. Using the WebSocket protocol from other specifications 11.12. WebSocket Version Number Registry
This specification requests the creation of a new IANA registry for
WebSocket Version Numbers to be used with the WebSocket protocol in
accordance with the principles set out in RFC 5226 [RFC5226].
As part of this registry IANA will maintain the following
information:
Version Number
The version number to be used in the Sec-WebSocket-Version as
specified in Section 5.1 of this specification. The value must be
a whole number (zero or higher).
Reference
The RFC requesting a new version number.
WebSocket Version Numbers are to be subject to RFC Required as per
RFC5226 [RFC5226].
IANA is asked to add initial values to the registry, with suggested
numerical values as these have been used in past versions of this
protocol.
Version Number | Reference
-+----------------+-----------------------------------------+-
| 0 + draft-ietf-hybi-thewebsocketprotocol-00 |
-+----------------+-----------------------------------------+-
| 1 + draft-ietf-hybi-thewebsocketprotocol-01 |
-+----------------+-----------------------------------------+-
| 2 + draft-ietf-hybi-thewebsocketprotocol-02 |
-+----------------+-----------------------------------------+-
| 3 + draft-ietf-hybi-thewebsocketprotocol-03 |
-+----------------+-----------------------------------------+-
| 4 + draft-ietf-hybi-thewebsocketprotocol-04 |
-+----------------+-----------------------------------------+-
| 5 + draft-ietf-hybi-thewebsocketprotocol-05 |
-+----------------+-----------------------------------------+-
| 6 + draft-ietf-hybi-thewebsocketprotocol-06 |
-+----------------+-----------------------------------------+-
| 7 + draft-ietf-hybi-thewebsocketprotocol-07 |
-+----------------+-----------------------------------------+-
| 8 + draft-ietf-hybi-thewebsocketprotocol-08 |
-+----------------+-----------------------------------------+-
11.13. WebSocket Close Code Number Registry
This specification requests the creation of a new IANA registry for
WebSocket Connection Close Code Numbers in accordance with the
principles set out in RFC 5226 [RFC5226].
As part of this registry IANA will maintain the following
information:
Status Code
The Status Code which denotes a reson for a WebSocket connection
closure as per Section 7.4 of this document. The status code is
an integer number.
Meaning
The meaning of the status code.
Contact
A contact for the entity reserving the status code.
Reference
The stable document requesting the status codes and defining their
meaning, required for status codes in the range 1000-2999.
WebSocket Close Code Numbers are to be subject to different
registration requirements depending on their range. Unless otherwise
specified, requests are subject to Standards Action as per RFC5226
[RFC5226]. Requests for status codes for use by this protocol or
subsequent versions are subject to Standards Action and should be
granted status codes in the range 1000-1999. Requests for status
codes for use by extensions are subject to Specification Required and
should be granted Status Codes in the range 2000-2999. Requests for
status codes for use by libraries and frameworks are subject to First
Come First Served and should be granted in the range 3000-3999. The
range of status codes from 4000-4999 is designated for Private Use by
application code. Requests should indicate whether they are
requesting status codes for use by the WebSocket protocol (or a
future version of the protocol), by extensions, or by libraries and
frameworks.
IANA is asked to add initial values to the registry, with suggested
numerical values as these have been used in past versions of this
protocol.
|Status Code | Meaning | Contact | Reference |
-+------------+-----------------+---------------+-----------|
| 1000 | Normal Closure | hybi@ietf.org | RFC XXXX |
-+------------+-----------------+---------------+-----------|
| 1001 | Going Away | hybi@ietf.org | RFC XXXX |
-+------------+-----------------+---------------+-----------|
| 1002 | Protocol error | hybi@ietf.org | RFC XXXX |
-+------------+-----------------+---------------+-----------|
| 1003 | Unsupported Data| hybi@ietf.org | RFC XXXX |
-+------------+-----------------+---------------+-----------|
| 1004 | Frame Too Large | hybi@ietf.org | RFC XXXX |
-+------------+-----------------+---------------+-----------|
| 1005 | No Status Rcvd | hybi@ietf.org | RFC XXXX |
-+------------+-----------------+---------------+-----------|
| 1006 | Abnormal Closure| hybi@ietf.org | RFC XXXX |
-+------------+-----------------+---------------+-----------|
11.14. WebSocket Opcode Registry
This specification requests the creation of a new IANA registry for
WebSocket Opcodes in accordance with the principles set out in RFC
5226 [RFC5226].
As part of this registry IANA will maintain the following
information:
Opcode
The opcode denotes the frame type of the WebSocket frame, as
defined in Section 4.2. The status code is an integer number
between 0 and 15, inclusive.
Meaning
The meaning of the opcode code.
Reference
The specification requesting the opcode.
WebSocket Opcode numbers are subject to Standards Action as per
RFC5226 [RFC5226].
IANA is asked to add initial values to the registry, with suggested
numerical values as these have been used in past versions of this
protocol.
|Opcode | Meaning | Reference |
-+--------+-------------------------------------+-----------|
| 0 | Continuation Frame | RFC XXXX |
-+--------+-------------------------------------+-----------|
| 1 | Text Frame | RFC XXXX |
-+--------+-------------------------------------+-----------|
| 2 | Binary Frame | RFC XXXX |
-+--------+-------------------------------------+-----------|
| 8 | Connection Close Frame | RFC XXXX |
-+--------+-------------------------------------+-----------|
| 9 | Ping Frame | RFC XXXX |
-+--------+-------------------------------------+-----------|
| 10 | Pong Frame | RFC XXXX |
-+--------+-------------------------------------+-----------|
11.15. WebSocket Framing Header Bits Registry
This specification requests the creation of a new IANA registry for
WebSocket Framing Header Bits in accordance with the principles set
out in RFC 5226 [RFC5226]. This registry controls assignment of the
bits marked RSV1, RSV2, and RSV3 in Section 4.2.
These bits are reserved for future versions or extensions of this
specification.
WebSocket Framing Header Bits assignments are subject to Standards
Action per RFC 5226 [RFC5226].
12. Using the WebSocket protocol from Other Specifications
The WebSocket protocol is intended to be used by another The WebSocket protocol is intended to be used by another
specification to provide a generic mechanism for dynamic author- specification to provide a generic mechanism for dynamic author-
defined content, e.g. in a specification defining a scripted API. defined content, e.g. in a specification defining a scripted API.
Such a specification first needs to "establish a WebSocket Such a specification first needs to _Establish a WebSocket
connection", providing that algorithm with: Connection_, providing that algorithm with:
o The destination, consisting of a /host/ and a /port/. o The destination, consisting of a /host/ and a /port/.
o A /resource name/, which allows for multiple services to be o A /resource name/, which allows for multiple services to be
identified at one host and port. identified at one host and port.
o A /secure/ flag, which is true if the connection is to be o A /secure/ flag, which is true if the connection is to be
encrypted, and false otherwise. encrypted, and false otherwise.
o An ASCII serialization of an origin that is being made responsible o An ASCII serialization of an origin that is being made responsible
for the connection. [I-D.ietf-websec-origin] for the connection. [I-D.ietf-websec-origin]
o Optionally a string identifying a protocol that is to be layered o Optionally a string identifying a protocol that is to be layered
over the WebSocket connection. over the WebSocket connection.
The /host/, /port/, /resource name/, and /secure/ flag are usually The /host/, /port/, /resource name/, and /secure/ flag are usually
obtained from a URI using the steps to parse a WebSocket URI's obtained from a URI using the steps to parse a WebSocket URI's
components. These steps fail if the URI does not specify a components. These steps fail if the URI does not specify a
WebSocket. WebSocket.
If a connection can be established, then it is said that the
"WebSocket connection is established".
If at any time the connection is to be closed, then the specification If at any time the connection is to be closed, then the specification
needs to use the "close the WebSocket connection" algorithm. needs to use the _Close the WebSocket Connection_ algorithm
(Section 7.1.1).
When the connection is closed, for any reason including failure to Section 7.1.4 defines when _The WebSocket Connection is Closed_.
establish the connection in the first place, it is said that the
"WebSocket connection is closed".
While a connection is open, the specification will need to handle the While a connection is open, the specification will need to handle the
cases when "a WebSocket message has been received" with text /data/. cases when _A WebSocket Message Has Been Received_ (Section 6.2).
To send some text /data/ to an open connection, the specification To send some data /data/ to an open connection, the specification
needs to "send /data/ using the WebSocket". needs to _Send a WebSocket Message_ (Section 6.1).
12. Acknowledgements 13. Acknowledgements
Special thanks are due to Ian Hickson, who was the original author Special thanks are due to Ian Hickson, who was the original author
and editor of this protocol. The initial design of this and editor of this protocol. The initial design of this
specification benefitted from the participation of many people in the specification benefitted from the participation of many people in the
WHATWG and WHATWG mailing list. Contributions to that specification WHATWG and WHATWG mailing list. Contributions to that specification
are not tracked by section, but a list of all who contributed to that are not tracked by section, but a list of all who contributed to that
specification is given in the WHATWG HTML specification at specification is given in the WHATWG HTML specification at
http://whatwg.org/html5. http://whatwg.org/html5.
Special thanks also to John Tamplin for providing a significant Special thanks also to John Tamplin for providing a significant
amount of text for the Data Framing section of this specification. amount of text for the Data Framing section of this specification.
Special thanks also to Adam Barth for providing a significant amount Special thanks also to Adam Barth for providing a significant amount
of text and background research for the Data Masking section of this of text and background research for the Data Masking section of this
specification. specification.
13. References 14. References
13.1. Normative References 14.1. Normative References
[ANSI.X3-4.1986] [ANSI.X3-4.1986]
American National Standards Institute, "Coded Character American National Standards Institute, "Coded Character
Set - 7-bit American Standard Code for Information Set - 7-bit American Standard Code for Information
Interchange", ANSI X3.4, 1986. Interchange", ANSI X3.4, 1986.
[FIPS.180-2.2002] [FIPS.180-2.2002]
National Institute of Standards and Technology, "Secure National Institute of Standards and Technology, "Secure
Hash Standard", FIPS PUB 180-2, August 2002, <http:// Hash Standard", FIPS PUB 180-2, August 2002, <http://
csrc.nist.gov/publications/fips/fips180-2/fips180-2.pdf>. csrc.nist.gov/publications/fips/fips180-2/fips180-2.pdf>.
skipping to change at page 55, line 29 skipping to change at page 65, line 29
[RFC1951] Deutsch, P., "DEFLATE Compressed Data Format Specification [RFC1951] Deutsch, P., "DEFLATE Compressed Data Format Specification
version 1.3", RFC 1951, May 1996. version 1.3", RFC 1951, May 1996.
[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.
[RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H., [RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext
Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999. Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.
[RFC2817] Khare, R. and S. Lawrence, "Upgrading to TLS Within
HTTP/1.1", RFC 2817, May 2000.
[RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818, May 2000. [RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818, May 2000.
[RFC3490] Faltstrom, P., Hoffman, P., and A. Costello, [RFC3490] Faltstrom, P., Hoffman, P., and A. Costello,
"Internationalizing Domain Names in Applications (IDNA)", "Internationalizing Domain Names in Applications (IDNA)",
RFC 3490, March 2003. RFC 3490, March 2003.
[RFC3492] Costello, A., "Punycode: A Bootstring encoding of Unicode
for Internationalized Domain Names in Applications
(IDNA)", RFC 3492, March 2003.
[RFC3548] Josefsson, S., "The Base16, Base32, and Base64 Data [RFC3548] Josefsson, S., "The Base16, Base32, and Base64 Data
Encodings", RFC 3548, July 2003. Encodings", RFC 3548, July 2003.
[RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO [RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO
10646", STD 63, RFC 3629, November 2003. 10646", STD 63, RFC 3629, November 2003.
[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.
[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, Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, January 2005. RFC 3986, January 2005.
[RFC3987] Duerst, M. and M. Suignard, "Internationalized Resource [RFC3987] Duerst, M. and M. Suignard, "Internationalized Resource
Identifiers (IRIs)", RFC 3987, January 2005. Identifiers (IRIs)", RFC 3987, January 2005.
[RFC4086] Eastlake, D., Schiller, J., and S. Crocker, "Randomness
Requirements for Security", BCP 106, RFC 4086, June 2005.
[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.
[RFC6066] Eastlake, D., "Transport Layer Security (TLS) Extensions: [RFC6066] Eastlake, D., "Transport Layer Security (TLS) Extensions:
Extension Definitions", RFC 6066, January 2011. Extension Definitions", RFC 6066, January 2011.
[RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data [RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data
Encodings", RFC 4648, October 2006. Encodings", RFC 4648, October 2006.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
May 2008.
[RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax [RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, RFC 5234, January 2008. Specifications: ABNF", STD 68, RFC 5234, January 2008.
13.2. Informative References 14.2. Informative References
[WSAPI] Hickson, I., "The Web Sockets API", August 2010, [WSAPI] Hickson, I., "The Web Sockets API", August 2010,
<http://dev.w3.org/html5/websockets/>. <http://dev.w3.org/html5/websockets/>.
[I-D.ietf-httpstate-cookie] [I-D.ietf-httpstate-cookie]
Barth, A., "HTTP State Management Mechanism", Barth, A., "HTTP State Management Mechanism",
draft-ietf-httpstate-cookie-20 (work in progress), draft-ietf-httpstate-cookie-20 (work in progress),
December 2010. December 2010.
[I-D.ietf-websec-origin] [I-D.ietf-websec-origin]
skipping to change at page 57, line 5 skipping to change at page 66, line 51
Specification version 3.3", RFC 1950, May 1996. Specification version 3.3", RFC 1950, May 1996.
[RFC5321] Klensin, J., "Simple Mail Transfer Protocol", RFC 5321, [RFC5321] Klensin, J., "Simple Mail Transfer Protocol", RFC 5321,
October 2008. October 2008.
[RFC6202] Loreto, S., Saint-Andre, P., Salsano, S., and G. Wilkins, [RFC6202] Loreto, S., Saint-Andre, P., Salsano, S., and G. Wilkins,
"Known Issues and Best Practices for the Use of Long "Known Issues and Best Practices for the Use of Long
Polling and Streaming in Bidirectional HTTP", RFC 6202, Polling and Streaming in Bidirectional HTTP", RFC 6202,
April 2011. April 2011.
[W3C.REC-wsc-ui-20100812]
Saldhana, A. and T. Roessler, "Web Security Context: User
Interface Guidelines", World Wide Web Consortium
Recommendation REC-wsc-ui-20100812, August 2010,
<http://www.w3.org/TR/2010/REC-wsc-ui-20100812>.
Author's Address Author's Address
Ian Fette Ian Fette
Google, Inc. Google, Inc.
Email: ifette+ietf@google.com Email: ifette+ietf@google.com
URI: http://www.ianfette.com/ URI: http://www.ianfette.com/
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