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Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- ** The abstract seems to contain references ([HTML5]), which it shouldn't. Please replace those with straight textual mentions of the documents in question. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year == The document doesn't use any RFC 2119 keywords, yet has text resembling RFC 2119 boilerplate text. -- The document date (July 7, 2009) is 5399 days in the past. Is this intentional? Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) -- Possible downref: Non-RFC (?) normative reference: ref. 'HTML5' ** Obsolete normative reference: RFC 2109 (Obsoleted by RFC 2965) ** Obsolete normative reference: RFC 2246 (Obsoleted by RFC 4346) ** Obsolete normative reference: RFC 2616 (Obsoleted by RFC 7230, RFC 7231, RFC 7232, RFC 7233, RFC 7234, RFC 7235) ** Obsolete normative reference: RFC 2965 (Obsoleted by RFC 6265) Summary: 6 errors (**), 0 flaws (~~), 2 warnings (==), 2 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group I. Hickson 3 Internet-Draft Google, Inc. 4 Intended status: Standards Track July 7, 2009 5 Expires: January 8, 2010 7 The Web Socket protocol 8 draft-hixie-thewebsocketprotocol-18 10 Status of this Memo 12 This Internet-Draft is submitted to IETF in full conformance with the 13 provisions of BCP 78 and BCP 79. 15 Internet-Drafts are working documents of the Internet Engineering 16 Task Force (IETF), its areas, and its working groups. Note that 17 other groups may also distribute working documents as Internet- 18 Drafts. 20 Internet-Drafts are draft documents valid for a maximum of six months 21 and may be updated, replaced, or obsoleted by other documents at any 22 time. It is inappropriate to use Internet-Drafts as reference 23 material or to cite them other than as "work in progress." 25 The list of current Internet-Drafts can be accessed at 26 http://www.ietf.org/ietf/1id-abstracts.txt. 28 The list of Internet-Draft Shadow Directories can be accessed at 29 http://www.ietf.org/shadow.html. 31 This Internet-Draft will expire on January 8, 2010. 33 Copyright Notice 35 Copyright (c) 2009 IETF Trust and the persons identified as the 36 document authors. All rights reserved. 38 This document is subject to BCP 78 and the IETF Trust's Legal 39 Provisions Relating to IETF Documents in effect on the date of 40 publication of this document (http://trustee.ietf.org/license-info). 41 Please review these documents carefully, as they describe your rights 42 and restrictions with respect to this document. 44 Abstract 46 This protocol enables two-way communication between a user agent 47 running untrusted code running in a controlled environment to a 48 remote host that understands the protocol. It is intended to fail to 49 communicate with servers of pre-existing protocols like SMTP or HTTP, 50 while allowing HTTP servers to opt-in to supporting this protocol if 51 desired. It is designed to be easy to implement on the server side. 53 Author's note 55 This document is automatically generated from the same source 56 document as the HTML5 specification. [HTML5] 58 Table of Contents 60 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 61 1.1. Security model . . . . . . . . . . . . . . . . . . . . . . 4 62 2. Conformance requirements . . . . . . . . . . . . . . . . . . . 5 63 3. Client-side requirements . . . . . . . . . . . . . . . . . . . 6 64 3.1. Handshake . . . . . . . . . . . . . . . . . . . . . . . . 6 65 3.2. Data framing . . . . . . . . . . . . . . . . . . . . . . . 13 66 3.3. Handling errors in UTF-8 . . . . . . . . . . . . . . . . . 14 67 4. Server-side requirements . . . . . . . . . . . . . . . . . . . 15 68 4.1. Minimal handshake . . . . . . . . . . . . . . . . . . . . 15 69 4.2. Handshake details . . . . . . . . . . . . . . . . . . . . 16 70 4.3. Data framing . . . . . . . . . . . . . . . . . . . . . . . 17 71 5. Closing the connection . . . . . . . . . . . . . . . . . . . . 18 72 6. Security considerations . . . . . . . . . . . . . . . . . . . 19 73 7. IANA considerations . . . . . . . . . . . . . . . . . . . . . 20 74 8. Normative References . . . . . . . . . . . . . . . . . . . . . 21 75 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 22 77 1. Introduction 79 The Web Socket protocol is designed on the principle that there 80 should be minimal framing (the only framing that exists is to make 81 the protocol frame-based instead of stream-based, and to support a 82 distinction between Unicode text and binary frames). It is expected 83 that metadata would be layered on top of Web Socket by the 84 application layer, in the same way that metadata is layered on top of 85 TCP/IP by the application layer (HTTP). 87 Conceptually, Web Socket is really just a layer on top of TCP/IP that 88 adds a Web "origin"-based security model for browsers; adds an 89 addressing and protocol naming mechanism to support multiple services 90 on one port and multiple host names on one IP address; and layers a 91 framing mechanism on top of TCP to get back to the IP packet 92 mechanism that TCP is built on, but without length limits. Other 93 than that, it adds nothing. Basically it is intended to be as close 94 as possible to just exposing raw TCP/IP to script as possible given 95 the constraints of the Web. It's also designed in such a way that its 96 servers can share a port with HTTP servers, by having its handshake 97 be a valid HTTP Upgrade handshake also. 99 1.1. Security model 101 The Web Socket protocol uses the origin model used by Web browsers to 102 restrict which Web pages can contact a Web Socket server when the Web 103 Socket protocol is used from a Web page. Naturally, when the Web 104 Socket protocol is used directly (not from a Web page), the origin 105 model is not useful, as the client can provide any arbitrary origin 106 string. 108 2. Conformance requirements 110 All diagrams, examples, and notes in this specification are non- 111 normative, as are all sections explicitly marked non-normative. 112 Everything else in this specification is normative. 114 The key words "MUST", "MUST NOT", "REQUIRED", "SHOULD", "SHOULD NOT", 115 "RECOMMENDED", "MAY", and "OPTIONAL" in the normative parts of this 116 document are to be interpreted as described in RFC2119. For 117 readability, these words do not appear in all uppercase letters in 118 this specification. [RFC2119] 120 Requirements phrased in the imperative as part of algorithms (such as 121 "strip any leading space characters" or "return false and abort these 122 steps") are to be interpreted with the meaning of the key word 123 ("must", "should", "may", etc) used in introducing the algorithm. 125 Conformance requirements phrased as algorithms or specific steps may 126 be implemented in any manner, so long as the end result is 127 equivalent. (In particular, the algorithms defined in this 128 specification are intended to be easy to follow, and not intended to 129 be performant.) 131 Implementations may impose implementation-specific limits on 132 otherwise unconstrained inputs, e.g. to prevent denial of service 133 attacks, to guard against running out of memory, or to work around 134 platform-specific limitations. 136 The conformance classes defined by this specification are user agents 137 and servers. 139 3. Client-side requirements 141 _This section only applies to user agents, not to servers._ 143 NOTE: This specification doesn't currently define a limit to the 144 number of simultaneous connections that a client can establish to a 145 server. 147 3.1. Handshake 149 When the user agent is to *establish a Web Socket connection* to a 150 host /host/, optionally on port /port/, from an origin /origin/, with 151 a flag /secure/, with a particular /resource name/, and optionally 152 with a particular /protocol/, it must run the following steps. 154 NOTE: The /host/ and /origin/ strings will be all-lowercase when this 155 algorithm is invoked. 157 1. If there is no explicit /port/, then: if /secure/ is false, let 158 /port/ be 81, otherwise let /port/ be 815. 160 2. If the user agent already has a Web Socket connection to the 161 remote host identified by /host/ (even if known by another 162 name), wait until that connection has been established or for 163 that connection to have failed. 165 NOTE: This makes it harder for a script to perform a denial of 166 service attack by just opening a large number of Web Socket 167 connections to a remote host. 169 NOTE: There is no limit to the number of established Web Socket 170 connections a user agent can have with a single remote host. 171 Servers can refuse to connect users with an excessive number of 172 connections, or disconnect resource-hogging users when suffering 173 high load. 175 3. If the user agent is configured to use a proxy to connect to 176 host /host/ and/or port /port/, then connect to that proxy and 177 ask it to open a TCP/IP connection to the host given by /host/ 178 and the port given by /port/. 180 EXAMPLE: For example, if the user agent uses an HTTP proxy 181 for all traffic, then if it was to try to connect to port 80 182 on server example.com, it might send the following lines to 183 the proxy server: 185 CONNECT example.com:80 HTTP/1.1 186 Host: example.com 188 If there was a password, the connection might look like: 190 CONNECT example.com:80 HTTP/1.1 191 Host: example.com 192 Proxy-authorization: Basic ZWRuYW1vZGU6bm9jYXBlcyE= 194 Otherwise, if the user agent is not configured to use a proxy, 195 then open a TCP/IP connection to the host given by /host/ and 196 the port given by /port/. 198 4. If the connection could not be opened, then fail the Web Socket 199 connection and abort these steps. 201 5. If /secure/ is true, perform a TLS handshake over the 202 connection. If this fails (e.g. the server's certificate could 203 not be verified), then fail the Web Socket connection and abort 204 these steps. Otherwise, all further communication on this 205 channel must run through the encrypted tunnel. [RFC2246] 207 6. Send the following bytes to the remote side (the server): 209 47 45 54 20 211 Send the /resource name/ value, encoded as US-ASCII. 213 Send the following bytes: 215 20 48 54 54 50 2f 31 2e 31 0d 0a 55 70 67 72 61 216 64 65 3a 20 57 65 62 53 6f 63 6b 65 74 0d 0a 43 217 6f 6e 6e 65 63 74 69 6f 6e 3a 20 55 70 67 72 61 218 64 65 0d 0a 220 NOTE: The string "GET ", the path, " HTTP/1.1", CRLF, the string 221 "Upgrade: WebSocket", CRLF, and the string "Connection: 222 Upgrade", CRLF. 224 7. Send the following bytes: 226 48 6f 73 74 3a 20 228 Send the /host/ value, encoded as US-ASCII. 230 Send the following bytes: 232 0d 0a 234 NOTE: The string "Host: ", the host, and CRLF. 236 8. Send the following bytes: 238 4f 72 69 67 69 6e 3a 20 240 Send the /origin/ value, encoded as US-ASCII. 242 NOTE: The /origin/ value is a string that was passed to this 243 algorithm. 245 Send the following bytes: 247 0d 0a 249 NOTE: The string "Origin: ", the origin, and CRLF. 251 9. If there is no /protocol/, then skip this step. 253 Otherwise, send the following bytes: 255 57 65 62 53 6f 63 6b 65 74 2d 50 72 6f 74 6f 63 256 6f 6c 3a 20 258 Send the /protocol/ value, encoded as US-ASCII. 260 Send the following bytes: 262 0d 0a 264 NOTE: The string "WebSocket-Protocol: ", the protocol, and CRLF. 266 10. If the client has any authentication information or cookies that 267 would be relevant to a resource accessed over HTTP, if /secure/ 268 is false, or HTTPS, if it is true, on host /host/, port /port/, 269 with /resource name/ as the path (and possibly query 270 parameters), then HTTP headers that would be appropriate for 271 that information should be sent at this point. [RFC2616] 272 [RFC2109] [RFC2965] 274 Each header must be on a line of its own (each ending with a CR 275 LF sequence). For the purposes of this step, each header must 276 not be split into multiple lines (despite HTTP otherwise 277 allowing this with continuation lines). 279 EXAMPLE: For example, if the server had a username and 280 password that applied to |http://example.com/socket|, and the 281 Web Socket was being opened to |ws://example.com:80/socket|, 282 it could send them: 284 Authorization: Basic d2FsbGU6ZXZl 286 However, it would not send them if the Web Socket was being 287 opened to |ws://example.com/socket|, as that uses a different 288 port (81, not 80). 290 11. Send the following bytes: 292 0d 0a 294 NOTE: Just a CRLF (a blank line). 296 12. Read the first 85 bytes from the server. If the connection 297 closes before 85 bytes are received, or if the first 85 bytes 298 aren't exactly equal to the following bytes, then fail the Web 299 Socket connection and abort these steps. 301 48 54 54 50 2f 31 2e 31 20 31 30 31 20 57 65 62 302 20 53 6f 63 6b 65 74 20 50 72 6f 74 6f 63 6f 6c 303 20 48 61 6e 64 73 68 61 6b 65 0d 0a 55 70 67 72 304 61 64 65 3a 20 57 65 62 53 6f 63 6b 65 74 0d 0a 305 43 6f 6e 6e 65 63 74 69 6f 6e 3a 20 55 70 67 72 306 61 64 65 0d 0a 308 NOTE: The string "HTTP/1.1 101 Web Socket Protocol Handshake", 309 CRLF, the string "Upgrade: WebSocket", CRLF, the string 310 "Connection: Upgrade", CRLF. 312 User agents may apply a timeout to this step, failing the Web 313 Socket connection if the server does not respond with the above 314 bytes within a suitable time period. 316 13. Let /headers/ be a list of name-value pairs, initially empty. 318 14. _Header_: Let /name/ and /value/ be empty byte arrays. 320 15. Read a byte from the server. 322 If the connection closes before this byte is received, then fail 323 the Web Socket connection and abort these steps. 325 Otherwise, handle the byte as described in the appropriate entry 326 below: 328 -> If the byte is 0x0d (ASCII CR) 329 If the /name/ byte array is empty, then jump to the headers 330 processing step. Otherwise, fail the Web Socket connection 331 and abort these steps. 333 -> If the byte is 0x0a (ASCII LF) 334 Fail the Web Socket connection and abort these steps. 336 -> If the byte is 0x3a (ASCII ":") 337 Move on to the next step. 339 -> If the byte is in the range 0x41 .. 0x5a (ASCII "A" .. "Z") 340 Append a byte whose value is the byte's value plus 0x20 to 341 the /name/ byte array and redo this step for the next byte. 343 -> Otherwise 344 Append the byte to the /name/ byte array and redo this step 345 for the next byte. 347 NOTE: This reads a header name, terminated by a colon, 348 converting upper-case ASCII letters to lowercase, and aborting 349 if a stray CR or LF is found. 351 16. Read a byte from the server. 353 If the connection closes before this byte is received, then fail 354 the Web Socket connection and abort these steps. 356 Otherwise, handle the byte as described in the appropriate entry 357 below: 359 -> If the byte is 0x20 (ASCII space) 360 Ignore the byte and move on to the next step. 362 -> Otherwise 363 Treat the byte as described by the list in the next step, 364 then move on to that next step for real. 366 NOTE: This skips past a space character after the colon, if 367 necessary. 369 17. Read a byte from the server. 371 If the connection closes before this byte is received, then fail 372 the Web Socket connection and abort these steps. 374 Otherwise, handle the byte as described in the appropriate entry 375 below: 377 -> If the byte is 0x0d (ASCII CR) 378 Move on to the next step. 380 -> If the byte is 0x0a (ASCII LF) 381 Fail the Web Socket connection and abort these steps. 383 -> Otherwise 384 Append the byte to the /name/ byte array and redo this step 385 for the next byte. 387 NOTE: This reads a header value, terminated by a CRLF. 389 18. Read a byte from the server. 391 If the connection closes before this byte is received, or if the 392 byte is not a 0x0a byte (ASCII LF), then fail the Web Socket 393 connection and abort these steps. 395 NOTE: This skips past the LF byte of the CRLF after the header. 397 19. Append an entry to the /headers/ list that has the name given by 398 the string obtained by interpreting the /name/ byte array as a 399 UTF-8 byte stream and the value given by the string obtained by 400 interpreting the /value/ byte array as a UTF-8 byte stream. 402 20. Return to the "Header" step above. 404 21. _Headers processing_: If there is not exactly one entry in the 405 /headers/ list whose name is "websocket-origin", or if there is 406 not exactly one entry in the /headers/ list whose name is 407 "websocket-location", or if the /protocol/ was specified but 408 there is not exactly one entry in the /headers/ list whose name 409 is "websocket-protocol", or if there are any entries in the 410 /headers/ list whose names are the empty string, then fail the 411 Web Socket connection and abort these steps. 413 22. Read a byte from the server. 415 If the connection closes before this byte is received, or if the 416 byte is not a 0x0a byte (ASCII LF), then fail the Web Socket 417 connection and abort these steps. 419 NOTE: This skips past the LF byte of the CRLF after the blank 420 line after the headers. 422 23. Handle each entry in the /headers/ list as follows: 424 -> If the entry's name is "websocket-origin|" 425 If the value is not exactly equal to /origin/, converted to 426 ASCII lowercase, then fail the Web Socket connection and 427 abort these steps. 429 -> If the entry's name is "websocket-location|" 430 If the value is not exactly equal to a string consisting of 431 the following components in the same order, then fail the Web 432 Socket connection and abort these steps: 434 1. The string "ws" if /secure/ is false and "wss" if 435 /secure/ is true 437 2. The three characters "://". 439 3. The value of /host/. 441 4. If /secure/ is false and /port/ is not 81, or if /secure/ 442 is true and /port/ is not 815: a ":" character followed 443 by the value of /port/. 445 5. The value of /resource name/. 447 -> If the entry's name is "websocket-protocol|" 448 If there was a /protocol/ specified, and the value is not 449 exactly equal to /protocol/, then fail the Web Socket 450 connection and abort these steps. (If no /protocol/ was 451 specified, the header is ignored.) 453 -> If the entry's name is "set-cookie|" or "set-cookie2|" or 454 another cookie-related header name 455 Handle the cookie as defined by the appropriate spec, with 456 the resource being the one with the host /host/, the port 457 /port/, the path (and possibly query parameters) /resource 458 name/, and the scheme |http| if /secure/ is false and |https| 459 if /secure/ is true. [RFC2109] [RFC2965] 461 -> Any other name 462 Ignore it. 464 24. The *Web Socket connection is established*. Now the user agent 465 must send and receive to and from the connection as described in 466 the next section. 468 To *fail the Web Socket connection*, the user agent must close the 469 Web Socket connection, and may report the problem to the user (which 470 would be especially useful for developers). However, user agents 471 must not convey the failure information to the script that attempted 472 the connection in a way distinguishable from the Web Socket being 473 closed normally. 475 3.2. Data framing 477 Once a Web Socket connection is established, the user agent must run 478 through the following state machine for the bytes sent by the server. 480 1. Try to read a byte from the server. Let /frame type/ be that 481 byte. 483 If no byte could be read because the Web Socket connection is 484 closed, then abort. 486 2. Handle the /frame type/ byte as follows: 488 If the high-order bit of the /frame type/ byte is set (i.e. if 489 /frame type/ _and_ed with 0x80 returns 0x80) 490 Run these steps. If at any point during these steps a read is 491 attempted but fails because the Web Socket connection is 492 closed, then abort. 494 1. Let /length/ be zero. 496 2. _Length_: Read a byte, let /b/ be that byte. 498 3. Let /b_v/ be integer corresponding to the low 7 bits of 499 /b/ (the value you would get by _and_ing /b/ with 0x7f). 501 4. Multiply /length/ by 128, add /b_v/ to that result, and 502 store the final result in /length/. 504 5. If the high-order bit of /b/ is set (i.e. if /b/ _and_ed 505 with 0x80 returns 0x80), then return to the step above 506 labeled _length_. 508 6. Read /length/ bytes. 510 7. Discard the read bytes. 512 If the high-order bit of the /frame type/ byte is _not_ set (i.e. 513 if /frame type/ _and_ed with 0x80 returns 0x00) 514 Run these steps. If at any point during these steps a read is 515 attempted but fails because the Web Socket connection is 516 closed, then abort. 518 1. Let /raw data/ be an empty byte array. 520 2. _Data_: Read a byte, let /b/ be that byte. 522 3. If /b/ is not 0xff, then append /b/ to /raw data/ and 523 return to the previous step (labeled _data_). 525 4. Interpret /raw data/ as a UTF-8 string, and store that 526 string in /data/. 528 5. If /frame type/ is 0x00, then *a message has been 529 received* with text /data/. Otherwise, discard the data. 531 3. Return to the first step to read the next byte. 533 If the user agent is faced with content that is too large to be 534 handled appropriately, then it must fail the Web Socket connection. 536 Once a Web Socket connection is established, the user agent must use 537 the following steps to *send /data/ using the Web Socket*: 539 1. Send a 0x00 byte to the server. 541 2. Encode /data/ using UTF-8 and send the resulting byte stream to 542 the server. 544 3. Send a 0xff byte to the server. 546 3.3. Handling errors in UTF-8 548 When a client is to interpret a byte stream as UTF-8 but finds that 549 the byte stream is not in fact a valid UTF-8 stream, then any bytes 550 or sequences of bytes that are not valid UTF-8 sequences must be 551 interpreted as a U+FFFD REPLACEMENT CHARACTER. 553 4. Server-side requirements 555 _This section only applies to servers._ 557 4.1. Minimal handshake 559 NOTE: This section describes the minimal requirements for a server- 560 side implementation of Web Sockets. 562 Listen on a port for TCP/IP. Upon receiving a connection request, 563 open a connection and send the following bytes back to the client: 565 48 54 54 50 2f 31 2e 31 20 31 30 31 20 57 65 62 566 20 53 6f 63 6b 65 74 20 50 72 6f 74 6f 63 6f 6c 567 20 48 61 6e 64 73 68 61 6b 65 0d 0a 55 70 67 72 568 61 64 65 3a 20 57 65 62 53 6f 63 6b 65 74 0d 0a 569 43 6f 6e 6e 65 63 74 69 6f 6e 3a 20 55 70 67 72 570 61 64 65 0d 0a 572 Send the string "WebSocket-Origin" followed by a U+003A COLON (":") 573 followed by the ASCII serialization of the origin from which the 574 server is willing to accept connections, followed by a CRLF pair 575 (0x0d 0x0a). 577 For instance: 579 WebSocket-Origin: http://example.com 581 Send the string "WebSocket-Location" followed by a U+003A COLON (":") 582 followed by the URL of the Web Socket script, followed by a CRLF pair 583 (0x0d 0x0a). 585 For instance: 587 WebSocket-Location: ws://example.com:80/demo 589 Send another CRLF pair (0x0d 0x0a). 591 Read data from the client until four bytes 0x0d 0x0a 0x0d 0x0a are 592 read. This data must either be discarded or handled as described in 593 the following section describing the handshake details. 595 If the connection isn't dropped at this point, go to the data framing 596 section. 598 4.2. Handshake details 600 The previous section ignores the data that is transmitted by the 601 client during the handshake. 603 The data sent by the client consists of a number of fields separated 604 by CR LF pairs (bytes 0x0d 0x0a). 606 The first field consists of three tokens separated by space 607 characters (byte 0x20). The middle token is the path being opened. 608 If the server supports multiple paths, then the server should echo 609 the value of this field in the initial handshake, as part of the URL 610 given on the |WebSocket-Location| line (after the appropriate scheme 611 and host). 613 If the first field does not have three tokens, the server should 614 abort the connection as it probably represents an errorneous client. 616 The remaining fields consist of name-value pairs, with the name part 617 separated from the value part by a colon and a space (bytes 0x3a 618 0x20). Of these, several are interesting: 620 Host (bytes 48 6f 73 74) 621 The value gives the hostname that the client intended to use when 622 opening the Web Socket. It would be of interest in particular to 623 virtual hosting environments, where one server might serve 624 multiple hosts, and might therefore want to return different data. 626 The right host has to be output as part of the URL given on the 627 |WebSocket-Location| line of the handshake described above, to 628 verify that the server knows that it is really representing that 629 host. 631 Origin (bytes 4f 72 69 67 69 6e) 632 The value gives the scheme, hostname, and port (if it's not the 633 default port for the given scheme) of the page that asked the 634 client to open the Web Socket. It would be interesting if the 635 server's operator had deals with operators of other sites, since 636 the server could then decide how to respond (or indeed, _whether_ 637 to respond) based on which site was requesting a connection. 639 If the server supports connections from more than one origin, then 640 the server should echo the value of this field in the initial 641 handshake, on the |WebSocket-Origin| line. 643 Other fields 644 Other fields can be used, such as "Cookie" or "Authorization", for 645 authentication purposes. 647 Any fields that lack the colon-space separator should be discarded 648 and may cause the server to disconnect. 650 4.3. Data framing 652 NOTE: This section only describes how to handle content that this 653 specification allows user agents to send (text). It doesn't handle 654 any arbitrary content in the same way that the requirements on user 655 agents defined earlier handle any content including possible future 656 extensions to the protocols. 658 The server must run through the following steps to process the bytes 659 sent by the client: 661 1. Read a byte from the client. Assuming everything is going 662 according to plan, it will be a 0x00 byte. If the byte is not a 663 0x00 byte, then the server may disconnect. 665 2. Let /raw data/ be an empty byte array. 667 3. _Data_: Read a byte, let /b/ be that byte. 669 4. If /b/ is not 0xff, then append /b/ to /raw data/ and return to 670 the previous step (labeled _data_). 672 5. Interpret /raw data/ as a UTF-8 string, and apply whatever 673 server-specific processing is to occur for the resulting string. 675 6. Return to the first step to read the next byte. 677 The server must run through the following steps to send strings to 678 the client: 680 1. Send a 0x00 byte to the client to indicate the start of a string. 682 2. Encode /data/ using UTF-8 and send the resulting byte stream to 683 the client. 685 3. Send a 0xff byte to the client to indicate the end of the 686 message. 688 5. Closing the connection 690 To *close the Web Socket connection*, either the user agent or the 691 server closes the TCP/IP connection. There is no closing handshake. 692 Whether the user agent or the server closes the connection, it is 693 said that the *Web Socket connection is closed*. 695 Servers may close the Web Socket connection whenever desired. 697 User agents should not close the Web Socket connection arbitrarily. 699 6. Security considerations 701 ** ISSUE ** ... 703 7. IANA considerations 705 ** ISSUE ** ...(two URI schemes, two ports, HTTP Upgrade keyword) 707 8. Normative References 709 [HTML5] Hickson, I., "HTML5", July 2009. 711 [RFC2109] Kristol, D. and L. Montulli, "HTTP State Management 712 Mechanism", RFC 2109, February 1997. 714 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 715 Requirement Levels", BCP 14, RFC 2119, March 1997. 717 [RFC2246] Dierks, T. and C. Allen, "The TLS Protocol Version 1.0", 718 RFC 2246, January 1999. 720 [RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H., 721 Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext 722 Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999. 724 [RFC2965] Kristol, D. and L. Montulli, "HTTP State Management 725 Mechanism", RFC 2965, October 2000. 727 Author's Address 729 Ian Hickson 730 Google, Inc. 732 Email: ian@hixie.ch 733 URI: http://ln.hixie.ch/