[Docs] [txt|pdf] [Tracker] [Email] [Diff1] [Diff2] [Nits]

Versions: 00 01 02 03 05 06 07 10 11 12 13 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 draft-ietf-hybi-thewebsocketprotocol

Network Working Group                                         I. Hickson
Internet-Draft                                              Google, Inc.
Intended status: Standards Track                           July 28, 2009
Expires: January 29, 2010


                        The Web Socket protocol
                  draft-hixie-thewebsocketprotocol-26

Status of this Memo

   This Internet-Draft is submitted to IETF in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups.  Note that
   other groups may also distribute working documents as Internet-
   Drafts.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   The list of current Internet-Drafts can be accessed at
   http://www.ietf.org/ietf/1id-abstracts.txt.

   The list of Internet-Draft Shadow Directories can be accessed at
   http://www.ietf.org/shadow.html.

   This Internet-Draft will expire on January 29, 2010.

Copyright Notice

   Copyright (c) 2009 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents in effect on the date of
   publication of this document (http://trustee.ietf.org/license-info).
   Please review these documents carefully, as they describe your rights
   and restrictions with respect to this document.









Hickson                 Expires January 29, 2010                [Page 1]

Internet-Draft           The Web Socket protocol               July 2009


Abstract

   This protocol enables two-way communication between a user agent
   running untrusted code running in a controlled environment to a
   remote host that understands the protocol.  It is intended to fail to
   communicate with servers of pre-existing protocols like SMTP or HTTP,
   while allowing HTTP servers to opt-in to supporting this protocol if
   desired.  It is designed to be easy to implement on the server side.











































Hickson                 Expires January 29, 2010                [Page 2]

Internet-Draft           The Web Socket protocol               July 2009


Author's note

   This document is automatically generated from the same source
   document as the HTML5 specification.  [HTML5]


Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
     1.1.  Security model . . . . . . . . . . . . . . . . . . . . . .  4
     1.2.  Relationship to TCP/IP and HTTP  . . . . . . . . . . . . .  4
     1.3.  Establishing a connection  . . . . . . . . . . . . . . . .  4
   2.  Conformance requirements . . . . . . . . . . . . . . . . . . .  6
   3.  Client-side requirements . . . . . . . . . . . . . . . . . . .  7
     3.1.  Handshake  . . . . . . . . . . . . . . . . . . . . . . . .  7
     3.2.  Data framing . . . . . . . . . . . . . . . . . . . . . . . 14
     3.3.  Handling errors in UTF-8 . . . . . . . . . . . . . . . . . 15
   4.  Server-side requirements . . . . . . . . . . . . . . . . . . . 16
     4.1.  Minimal handshake  . . . . . . . . . . . . . . . . . . . . 16
     4.2.  Handshake details  . . . . . . . . . . . . . . . . . . . . 17
     4.3.  Data framing . . . . . . . . . . . . . . . . . . . . . . . 18
   5.  Closing the connection . . . . . . . . . . . . . . . . . . . . 19
   6.  Security considerations  . . . . . . . . . . . . . . . . . . . 20
   7.  IANA considerations  . . . . . . . . . . . . . . . . . . . . . 21
   8.  Normative References . . . . . . . . . . . . . . . . . . . . . 22
   Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 23

























Hickson                 Expires January 29, 2010                [Page 3]

Internet-Draft           The Web Socket protocol               July 2009


1.  Introduction

   The Web Socket protocol is designed on the principle that there
   should be minimal framing (the only framing that exists is to make
   the protocol frame-based instead of stream-based, and to support a
   distinction between Unicode text and binary frames).  It is expected
   that metadata would be layered on top of Web Socket by the
   application layer, in the same way that metadata is layered on top of
   TCP/IP by the application layer (HTTP).

   Conceptually, Web Socket is really just a layer on top of TCP/IP that
   adds a Web "origin"-based security model for browsers; adds an
   addressing and protocol naming mechanism to support multiple services
   on one port and multiple host names on one IP address; and layers a
   framing mechanism on top of TCP to get back to the IP packet
   mechanism that TCP is built on, but without length limits.  Other
   than that, it adds nothing.  Basically it is intended to be as close
   as possible to just exposing raw TCP/IP to script as possible given
   the constraints of the Web. It's also designed in such a way that its
   servers can share a port with HTTP servers, by having its handshake
   be a valid HTTP Upgrade handshake also.

1.1.  Security model

   The Web Socket protocol uses the origin model used by Web browsers to
   restrict which Web pages can contact a Web Socket server when the Web
   Socket protocol is used from a Web page.  Naturally, when the Web
   Socket protocol is used directly (not from a Web page), the origin
   model is not useful, as the client can provide any arbitrary origin
   string.

1.2.  Relationship to TCP/IP and HTTP

   The Web Socket protocol is an independent TCP-based protocol.  It's
   only relationship to HTTP is that its handshake is interpreted by
   HTTP servers as an Upgrade request.

   The Web Socket protocol by default uses port 81 for regular Web
   Socket connections and port 815 for Web Socket connections tunneled
   over TLS.

1.3.  Establishing a connection

   There are several options for establishing a Web Socket connection.

   The simplest method is to use port 81 to get a direct connection to a
   Web Socket server.  However, this port may be blocked by firewalls.




Hickson                 Expires January 29, 2010                [Page 4]

Internet-Draft           The Web Socket protocol               July 2009


   The second simplest method is to use TLS encryption and port 815 to
   connect directly to a Web Socket server.  This is the preferred
   solution, as it is secure and correct.  However, TLS encryption can
   be computationally expensive, and port 815 might also be blocked by
   firewalls.

   To avoid firewalls, ports 80 and 443 might be used instead.  These
   are the HTTP and HTTPS ports.  Port 80 traffic, however, will often
   be intercepted by HTTP proxies, which can lead to the connection
   failing to be established.

   Port 443, using encryption, is therefore the most reliable solution.
   It is unlikely to be blocked by a firewall or intercepted by a proxy.
   However, again, TLS encryption can be computationally expensive.

   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
   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
   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
   based on the Web Socket protocol to be deployed.  In more elaborate
   setups (e.g. with load balancers and multiple servers), a dedicated
   set of hosts for Web Socket connections separate from the HTTP
   servers is probably easier to manage.


























Hickson                 Expires January 29, 2010                [Page 5]

Internet-Draft           The Web Socket protocol               July 2009


2.  Conformance requirements

   All diagrams, examples, and notes in this specification are non-
   normative, as are all sections explicitly marked non-normative.
   Everything else in this specification is normative.

   The key words "MUST", "MUST NOT", "REQUIRED", "SHOULD", "SHOULD NOT",
   "RECOMMENDED", "MAY", and "OPTIONAL" in the normative parts of this
   document are to be interpreted as described in RFC2119.  For
   readability, these words do not appear in all uppercase letters in
   this specification.  [RFC2119]

   Requirements phrased in the imperative as part of algorithms (such as
   "strip any leading space characters" or "return false and abort these
   steps") are to be interpreted with the meaning of the key word
   ("must", "should", "may", etc) used in introducing the algorithm.

   Conformance requirements phrased as algorithms or specific steps may
   be implemented in any manner, so long as the end result is
   equivalent.  (In particular, the algorithms defined in this
   specification are intended to be easy to follow, and not intended to
   be performant.)

   Implementations may impose implementation-specific limits on
   otherwise unconstrained inputs, e.g. to prevent denial of service
   attacks, to guard against running out of memory, or to work around
   platform-specific limitations.

   The conformance classes defined by this specification are user agents
   and servers.





















Hickson                 Expires January 29, 2010                [Page 6]

Internet-Draft           The Web Socket protocol               July 2009


3.  Client-side requirements

   _This section only applies to user agents, not to servers._

   NOTE: This specification doesn't currently define a limit to the
   number of simultaneous connections that a client can establish to a
   server.

3.1.  Handshake

   When the user agent is to *establish a Web Socket connection* to a
   host /host/, optionally on port /port/, from an origin /origin/, with
   a flag /secure/, with a particular /resource name/, and optionally
   with a particular /protocol/, it must run the following steps.

   NOTE: The /host/ and /origin/ strings will be all-lowercase when this
   algorithm is invoked.

   1.   If there is no explicit /port/, then: if /secure/ is false, let
        /port/ be 81, otherwise let /port/ be 815.

   2.   If the user agent already has a Web Socket connection to the
        remote host (IP address) identified by /host/, even if known by
        another name, wait until that connection has been established or
        for that connection to have failed.

        NOTE: This makes it harder for a script to perform a denial of
        service attack by just opening a large number of Web Socket
        connections to a remote host.

        NOTE: There is no limit to the number of established Web Socket
        connections a user agent can have with a single remote host.
        Servers can refuse to connect users with an excessive number of
        connections, or disconnect resource-hogging users when suffering
        high load.

   3.   If the user agent is configured to use a proxy when using the
        Web Socket protocol to connect to host /host/ and/or port
        /port/, then connect to that proxy and ask it to open a TCP/IP
        connection to the host given by /host/ and the port given by
        /port/.

           EXAMPLE: For example, if the user agent uses an HTTP proxy
           for all traffic, then if it was to try to connect to port 80
           on server example.com, it might send the following lines to
           the proxy server:





Hickson                 Expires January 29, 2010                [Page 7]

Internet-Draft           The Web Socket protocol               July 2009


              CONNECT example.com:80 HTTP/1.1
              Host: example.com

           If there was a password, the connection might look like:

              CONNECT example.com:80 HTTP/1.1
              Host: example.com
              Proxy-authorization: Basic ZWRuYW1vZGU6bm9jYXBlcyE=

        Otherwise, if the user agent is not configured to use a proxy,
        then open a TCP/IP connection to the host given by /host/ and
        the port given by /port/.

        NOTE: Implementations that do not expose explicit UI for
        selecting a proxy for Web Socket connections separate from other
        proxies are encouraged to use a SOCKS proxy for Web Socket
        connections, if available, or failing that, to prefer the proxy
        configured for HTTPS connections over the proxy configured for
        HTTP connections.

   4.   If the connection could not be opened, then fail the Web Socket
        connection and abort these steps.

   5.   If /secure/ is true, perform a TLS handshake over the
        connection.  If this fails (e.g. the server's certificate could
        not be verified), then fail the Web Socket connection and abort
        these steps.  Otherwise, all further communication on this
        channel must run through the encrypted tunnel.  [RFC2246]

   6.   Send the following bytes to the remote side (the server):

           47 45 54 20

        Send the /resource name/ value, encoded as US-ASCII.

        Send the following bytes:

           20 48 54 54 50 2f 31 2e  31 0d 0a 55 70 67 72 61
           64 65 3a 20 57 65 62 53  6f 63 6b 65 74 0d 0a 43
           6f 6e 6e 65 63 74 69 6f  6e 3a 20 55 70 67 72 61
           64 65 0d 0a

        NOTE: The string "GET ", the path, " HTTP/1.1", CRLF, the string
        "Upgrade: WebSocket", CRLF, and the string "Connection:
         Upgrade", CRLF.

   7.   Send the following bytes:




Hickson                 Expires January 29, 2010                [Page 8]

Internet-Draft           The Web Socket protocol               July 2009


           48 6f 73 74 3a 20

        Send the /host/ value, encoded as US-ASCII.

        Send the following bytes:

           0d 0a

        NOTE: The string "Host: ", the host, and CRLF.

   8.   Send the following bytes:

           4f 72 69 67 69 6e 3a 20

        Send the /origin/ value, encoded as US-ASCII.

        NOTE: The /origin/ value is a string that was passed to this
        algorithm.

        Send the following bytes:

           0d 0a

        NOTE: The string "Origin: ", the origin, and CRLF.

   9.   If there is no /protocol/, then skip this step.

        Otherwise, send the following bytes:

           57 65 62 53 6f 63 6b 65  74 2d 50 72 6f 74 6f 63
           6f 6c 3a 20

        Send the /protocol/ value, encoded as US-ASCII.

        Send the following bytes:

           0d 0a

        NOTE: The string "WebSocket-Protocol: ", the protocol, and CRLF.

   10.  If the client has any authentication information or cookies that
        would be relevant to a resource accessed over HTTP, if /secure/
        is false, or HTTPS, if it is true, on host /host/, port /port/,
        with /resource name/ as the path (and possibly query
        parameters), then HTTP headers that would be appropriate for
        that information should be sent at this point.  [RFC2616]
        [RFC2109] [RFC2965]




Hickson                 Expires January 29, 2010                [Page 9]

Internet-Draft           The Web Socket protocol               July 2009


        Each header must be on a line of its own (each ending with a CR
        LF sequence).  For the purposes of this step, each header must
        not be split into multiple lines (despite HTTP otherwise
        allowing this with continuation lines).

           EXAMPLE: For example, if the server had a username and
           password that applied to |http://example.com/socket|, and the
           Web Socket was being opened to |ws://example.com:80/socket|,
           it could send them:

              Authorization: Basic d2FsbGU6ZXZl

           However, it would not send them if the Web Socket was being
           opened to |ws://example.com/socket|, as that uses a different
           port (81, not 80).

   11.  Send the following bytes:

           0d 0a

        NOTE: Just a CRLF (a blank line).

   12.  Read the first 85 bytes from the server.  If the connection
        closes before 85 bytes are received, or if the first 85 bytes
        aren't exactly equal to the following bytes, then fail the Web
        Socket connection and abort these steps.

           48 54 54 50 2f 31 2e 31  20 31 30 31 20 57 65 62
           20 53 6f 63 6b 65 74 20  50 72 6f 74 6f 63 6f 6c
           20 48 61 6e 64 73 68 61  6b 65 0d 0a 55 70 67 72
           61 64 65 3a 20 57 65 62  53 6f 63 6b 65 74 0d 0a
           43 6f 6e 6e 65 63 74 69  6f 6e 3a 20 55 70 67 72
           61 64 65 0d 0a

        NOTE: The string "HTTP/1.1 101 Web Socket Protocol Handshake",
        CRLF, the string "Upgrade: WebSocket", CRLF, the string
        "Connection: Upgrade", CRLF.

        User agents may apply a timeout to this step, failing the Web
        Socket connection if the server does not respond with the above
        bytes within a suitable time period.

   13.  Let /headers/ be a list of name-value pairs, initially empty.

   14.  _Header_: Let /name/ and /value/ be empty byte arrays.

   15.  Read a byte from the server.




Hickson                 Expires January 29, 2010               [Page 10]

Internet-Draft           The Web Socket protocol               July 2009


        If the connection closes before this byte is received, then fail
        the Web Socket connection and abort these steps.

        Otherwise, handle the byte as described in the appropriate entry
        below:

        -> If the byte is 0x0d (ASCII CR)
           If the /name/ byte array is empty, then jump to the headers
           processing step.  Otherwise, fail the Web Socket connection
           and abort these steps.

        -> If the byte is 0x0a (ASCII LF)
           Fail the Web Socket connection and abort these steps.

        -> If the byte is 0x3a (ASCII ":")
           Move on to the next step.

        -> If the byte is in the range 0x41 .. 0x5a (ASCII "A" .. "Z")
           Append a byte whose value is the byte's value plus 0x20 to
           the /name/ byte array and redo this step for the next byte.

        -> Otherwise
           Append the byte to the /name/ byte array and redo this step
           for the next byte.

        NOTE: This reads a header name, terminated by a colon,
        converting upper-case ASCII letters to lowercase, and aborting
        if a stray CR or LF is found.

   16.  Read a byte from the server.

        If the connection closes before this byte is received, then fail
        the Web Socket connection and abort these steps.

        Otherwise, handle the byte as described in the appropriate entry
        below:

        -> If the byte is 0x20 (ASCII space)
           Ignore the byte and move on to the next step.

        -> Otherwise
           Treat the byte as described by the list in the next step,
           then move on to that next step for real.

        NOTE: This skips past a space character after the colon, if
        necessary.





Hickson                 Expires January 29, 2010               [Page 11]

Internet-Draft           The Web Socket protocol               July 2009


   17.  Read a byte from the server.

        If the connection closes before this byte is received, then fail
        the Web Socket connection and abort these steps.

        Otherwise, handle the byte as described in the appropriate entry
        below:

        -> If the byte is 0x0d (ASCII CR)
           Move on to the next step.

        -> If the byte is 0x0a (ASCII LF)
           Fail the Web Socket connection and abort these steps.

        -> Otherwise
           Append the byte to the /value/ byte array and redo this step
           for the next byte.

        NOTE: This reads a header value, terminated by a CRLF.

   18.  Read a byte from the server.

        If the connection closes before this byte is received, or if the
        byte is not a 0x0a byte (ASCII LF), then fail the Web Socket
        connection and abort these steps.

        NOTE: This skips past the LF byte of the CRLF after the header.

   19.  Append an entry to the /headers/ list that has the name given by
        the string obtained by interpreting the /name/ byte array as a
        UTF-8 byte stream and the value given by the string obtained by
        interpreting the /value/ byte array as a UTF-8 byte stream.

   20.  Return to the "Header" step above.

   21.  _Headers processing_: If there is not exactly one entry in the
        /headers/ list whose name is "websocket-origin", or if there is
        not exactly one entry in the /headers/ list whose name is
        "websocket-location", or if the /protocol/ was specified but
        there is not exactly one entry in the /headers/ list whose name
        is "websocket-protocol", or if there are any entries in the
        /headers/ list whose names are the empty string, then fail the
        Web Socket connection and abort these steps.

   22.  Read a byte from the server.

        If the connection closes before this byte is received, or if the
        byte is not a 0x0a byte (ASCII LF), then fail the Web Socket



Hickson                 Expires January 29, 2010               [Page 12]

Internet-Draft           The Web Socket protocol               July 2009


        connection and abort these steps.

        NOTE: This skips past the LF byte of the CRLF after the blank
        line after the headers.

   23.  Handle each entry in the /headers/ list as follows:

        -> If the entry's name is "websocket-origin"
           If the value is not exactly equal to /origin/, converted to
           ASCII lowercase, then fail the Web Socket connection and
           abort these steps.

        -> If the entry's name is "websocket-location"
           If the value is not exactly equal to a string consisting of
           the following components in the same order, then fail the Web
           Socket connection and abort these steps:

           1.  The string "ws" if /secure/ is false and "wss" if
               /secure/ is true

           2.  The three characters "://".

           3.  The value of /host/.

           4.  If /secure/ is false and /port/ is not 81, or if /secure/
               is true and /port/ is not 815: a ":" character followed
               by the value of /port/.

           5.  The value of /resource name/.

        -> If the entry's name is "websocket-protocol"
           If there was a /protocol/ specified, and the value is not
           exactly equal to /protocol/, then fail the Web Socket
           connection and abort these steps.  (If no /protocol/ was
           specified, the header is ignored.)

        -> If the entry's name is "set-cookie" or "set-cookie2" or
        another cookie-related header name
           Handle the cookie as defined by the appropriate spec, with
           the resource being the one with the host /host/, the port
           /port/, the path (and possibly query parameters) /resource
           name/, and the scheme |http| if /secure/ is false and |https|
           if /secure/ is true.  [RFC2109] [RFC2965]

        -> Any other name
           Ignore it.





Hickson                 Expires January 29, 2010               [Page 13]

Internet-Draft           The Web Socket protocol               July 2009


   24.  The *Web Socket connection is established*.  Now the user agent
        must send and receive to and from the connection as described in
        the next section.

   To *fail the Web Socket connection*, the user agent must close the
   Web Socket connection, and may report the problem to the user (which
   would be especially useful for developers).  However, user agents
   must not convey the failure information to the script that attempted
   the connection in a way distinguishable from the Web Socket being
   closed normally.

3.2.  Data framing

   Once a Web Socket connection is established, the user agent must run
   through the following state machine for the bytes sent by the server.

   1.  Try to read a byte from the server.  Let /frame type/ be that
       byte.

       If no byte could be read because the Web Socket connection is
       closed, then abort.

   2.  Handle the /frame type/ byte as follows:

       If the high-order bit of the /frame type/ byte is set (i.e. if
       /frame type/ _and_ed with 0x80 returns 0x80)
          Run these steps.  If at any point during these steps a read is
          attempted but fails because the Web Socket connection is
          closed, then abort.

          1.  Let /length/ be zero.

          2.  _Length_: Read a byte, let /b/ be that byte.

          3.  Let /b_v/ be integer corresponding to the low 7 bits of
              /b/ (the value you would get by _and_ing /b/ with 0x7f).

          4.  Multiply /length/ by 128, add /b_v/ to that result, and
              store the final result in /length/.

          5.  If the high-order bit of /b/ is set (i.e. if /b/ _and_ed
              with 0x80 returns 0x80), then return to the step above
              labeled _length_.

          6.  Read /length/ bytes.

          7.  Discard the read bytes.




Hickson                 Expires January 29, 2010               [Page 14]

Internet-Draft           The Web Socket protocol               July 2009


       If the high-order bit of the /frame type/ byte is _not_ set (i.e.
       if /frame type/ _and_ed with 0x80 returns 0x00)
          Run these steps.  If at any point during these steps a read is
          attempted but fails because the Web Socket connection is
          closed, then abort.

          1.  Let /raw data/ be an empty byte array.

          2.  _Data_: Read a byte, let /b/ be that byte.

          3.  If /b/ is not 0xff, then append /b/ to /raw data/ and
              return to the previous step (labeled _data_).

          4.  Interpret /raw data/ as a UTF-8 string, and store that
              string in /data/.

          5.  If /frame type/ is 0x00, then *a message has been
              received* with text /data/.  Otherwise, discard the data.

   3.  Return to the first step to read the next byte.

   If the user agent is faced with content that is too large to be
   handled appropriately, then it must fail the Web Socket connection.


   Once a Web Socket connection is established, the user agent must use
   the following steps to *send /data/ using the Web Socket*:

   1.  Send a 0x00 byte to the server.

   2.  Encode /data/ using UTF-8 and send the resulting byte stream to
       the server.

   3.  Send a 0xff byte to the server.

   If at any point there is a fatal problem with sending data to the
   server, the user agent must fail the Web Socket connection.

3.3.  Handling errors in UTF-8

   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.







Hickson                 Expires January 29, 2010               [Page 15]

Internet-Draft           The Web Socket protocol               July 2009


4.  Server-side requirements

   _This section only applies to servers._

4.1.  Minimal handshake

   NOTE: This section describes the minimal requirements for a server-
   side implementation of Web Sockets.

   Listen on a port for TCP/IP.  Upon receiving a connection request,
   open a connection and send the following bytes back to the client:

        48 54 54 50 2f 31 2e 31  20 31 30 31 20 57 65 62
        20 53 6f 63 6b 65 74 20  50 72 6f 74 6f 63 6f 6c
        20 48 61 6e 64 73 68 61  6b 65 0d 0a 55 70 67 72
        61 64 65 3a 20 57 65 62  53 6f 63 6b 65 74 0d 0a
        43 6f 6e 6e 65 63 74 69  6f 6e 3a 20 55 70 67 72
        61 64 65 0d 0a

   Send the string "WebSocket-Origin" followed by a U+003A COLON (":")
   followed by the ASCII serialization of the origin from which the
   server is willing to accept connections, followed by a CRLF pair
   (0x0d 0x0a).

      For instance:

           WebSocket-Origin: http://example.com

   Send the string "WebSocket-Location" followed by a U+003A COLON (":")
   followed by the URL of the Web Socket script, followed by a CRLF pair
   (0x0d 0x0a).

      For instance:

           WebSocket-Location: ws://example.com:80/demo

   Send another CRLF pair (0x0d 0x0a).

   Read data from the client until four bytes 0x0d 0x0a 0x0d 0x0a are
   read.  This data must either be discarded or handled as described in
   the following section describing the handshake details.

   If the connection isn't dropped at this point, go to the data framing
   section.







Hickson                 Expires January 29, 2010               [Page 16]

Internet-Draft           The Web Socket protocol               July 2009


4.2.  Handshake details

   The previous section ignores the data that is transmitted by the
   client during the handshake.

   The data sent by the client consists of a number of fields separated
   by CR LF pairs (bytes 0x0d 0x0a).

   The first field consists of three tokens separated by space
   characters (byte 0x20).  The middle token is the path being opened.
   If the server supports multiple paths, then the server should echo
   the value of this field in the initial handshake, as part of the URL
   given on the |WebSocket-Location| line (after the appropriate scheme
   and host).

   If the first field does not have three tokens, the server should
   abort the connection as it probably represents an errorneous client.


   The remaining fields consist of name-value pairs, with the name part
   separated from the value part by a colon and a space (bytes 0x3a
   0x20).  Of these, several are interesting:

   Host (bytes 48 6f 73 74)
      The value gives the hostname that the client intended to use when
      opening the Web Socket.  It would be of interest in particular to
      virtual hosting environments, where one server might serve
      multiple hosts, and might therefore want to return different data.

      The right host has to be output as part of the URL given on the
      |WebSocket-Location| line of the handshake described above, to
      verify that the server knows that it is really representing that
      host.

   Origin (bytes 4f 72 69 67 69 6e)
      The value gives the scheme, hostname, and port (if it's not the
      default port for the given scheme) of the page that asked the
      client to open the Web Socket.  It would be interesting if the
      server's operator had deals with operators of other sites, since
      the server could then decide how to respond (or indeed, _whether_
      to respond) based on which site was requesting a connection.

      If the server supports connections from more than one origin, then
      the server should echo the value of this field in the initial
      handshake, on the |WebSocket-Origin| line.






Hickson                 Expires January 29, 2010               [Page 17]

Internet-Draft           The Web Socket protocol               July 2009


   Other fields
      Other fields can be used, such as "Cookie" or "Authorization", for
      authentication purposes.

   Any fields that lack the colon-space separator should be discarded
   and may cause the server to disconnect.

4.3.  Data framing

   NOTE: This section only describes how to handle content that this
   specification allows user agents to send (text).  It doesn't handle
   any arbitrary content in the same way that the requirements on user
   agents defined earlier handle any content including possible future
   extensions to the protocols.

   The server must run through the following steps to process the bytes
   sent by the client:

   1.  Read a byte from the client.  Assuming everything is going
       according to plan, it will be a 0x00 byte.  If the byte is not a
       0x00 byte, then the server may disconnect.

   2.  Let /raw data/ be an empty byte array.

   3.  _Data_: Read a byte, let /b/ be that byte.

   4.  If /b/ is not 0xff, then append /b/ to /raw data/ and return to
       the previous step (labeled _data_).

   5.  Interpret /raw data/ as a UTF-8 string, and apply whatever
       server-specific processing is to occur for the resulting string.

   6.  Return to the first step to read the next byte.


   The server must run through the following steps to send strings to
   the client:

   1.  Send a 0x00 byte to the client to indicate the start of a string.

   2.  Encode /data/ using UTF-8 and send the resulting byte stream to
       the client.

   3.  Send a 0xff byte to the client to indicate the end of the
       message.






Hickson                 Expires January 29, 2010               [Page 18]

Internet-Draft           The Web Socket protocol               July 2009


5.  Closing the connection

   To *close the Web Socket connection*, either the user agent or the
   server closes the TCP/IP connection.  There is no closing handshake.
   Whether the user agent or the server closes the connection, it is
   said that the *Web Socket connection is closed*.

   Servers may close the Web Socket connection whenever desired.

   User agents should not close the Web Socket connection arbitrarily.









































Hickson                 Expires January 29, 2010               [Page 19]

Internet-Draft           The Web Socket protocol               July 2009


6.  Security considerations

   ** ISSUE ** ...
















































Hickson                 Expires January 29, 2010               [Page 20]

Internet-Draft           The Web Socket protocol               July 2009


7.  IANA considerations

   ** ISSUE ** ...(two URI schemes, two ports, HTTP Upgrade keyword)
















































Hickson                 Expires January 29, 2010               [Page 21]

Internet-Draft           The Web Socket protocol               July 2009


8.  Normative References

   [HTML5]    Hickson, I., "HTML5", July 2009.

   [RFC2109]  Kristol, D. and L. Montulli, "HTTP State Management
              Mechanism", RFC 2109, February 1997.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC2246]  Dierks, T. and C. Allen, "The TLS Protocol Version 1.0",
              RFC 2246, January 1999.

   [RFC2616]  Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
              Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext
              Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.

   [RFC2965]  Kristol, D. and L. Montulli, "HTTP State Management
              Mechanism", RFC 2965, October 2000.
































Hickson                 Expires January 29, 2010               [Page 22]

Internet-Draft           The Web Socket protocol               July 2009


Author's Address

   Ian Hickson
   Google, Inc.

   Email: ian@hixie.ch
   URI:   http://ln.hixie.ch/












































Hickson                 Expires January 29, 2010               [Page 23]


Html markup produced by rfcmarkup 1.108, available from http://tools.ietf.org/tools/rfcmarkup/