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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 Expires: July 13, 2009 January 9, 2009 6 The Web Socket protocol 7 draft-hixie-thewebsocketprotocol-01 9 Status of this Memo 11 This Internet-Draft is submitted to IETF in full conformance with the 12 provisions of BCP 78 and BCP 79. 14 Internet-Drafts are working documents of the Internet Engineering 15 Task Force (IETF), its areas, and its working groups. Note that 16 other groups may also distribute working documents as Internet- 17 Drafts. 19 Internet-Drafts are draft documents valid for a maximum of six months 20 and may be updated, replaced, or obsoleted by other documents at any 21 time. It is inappropriate to use Internet-Drafts as reference 22 material or to cite them other than as "work in progress." 24 The list of current Internet-Drafts can be accessed at 25 http://www.ietf.org/ietf/1id-abstracts.txt. 27 The list of Internet-Draft Shadow Directories can be accessed at 28 http://www.ietf.org/shadow.html. 30 This Internet-Draft will expire on July 13, 2009. 32 Copyright Notice 34 Copyright (c) 2009 IETF Trust and the persons identified as the 35 document authors. All rights reserved. 37 This document is subject to BCP 78 and the IETF Trust's Legal 38 Provisions Relating to IETF Documents 39 (http://trustee.ietf.org/license-info) in effect on the date of 40 publication of this document. Please review these documents 41 carefully, as they describe your rights and restrictions with respect 42 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, and is therefore a 56 subset of, the HTML5 specification produced by the WHATWG. [HTML5] 58 Table of Contents 60 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 61 2. Client-side requirements . . . . . . . . . . . . . . . . . . . 5 62 2.1. Handshake . . . . . . . . . . . . . . . . . . . . . . . . 5 63 2.2. Data framing . . . . . . . . . . . . . . . . . . . . . . . 10 64 3. Server-side requirements . . . . . . . . . . . . . . . . . . . 13 65 3.1. Minimal handshake . . . . . . . . . . . . . . . . . . . . 13 66 3.2. Handshake details . . . . . . . . . . . . . . . . . . . . 13 67 3.3. Data framing . . . . . . . . . . . . . . . . . . . . . . . 14 68 4. Closing the connection . . . . . . . . . . . . . . . . . . . . 16 69 5. Security considerations . . . . . . . . . . . . . . . . . . . 17 70 6. IANA considerations . . . . . . . . . . . . . . . . . . . . . 18 71 7. Normative References . . . . . . . . . . . . . . . . . . . . . 19 72 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 20 74 1. Introduction 76 ** ISSUE ** ... 78 2. Client-side requirements 80 _This section only applies to user agents, not to servers._ 82 NOTE: This specification doesn't currently define a limit to the 83 number of simultaneous connections that a client can establish to a 84 server. 86 2.1. Handshake 88 When the user agent is to *establish a Web Socket connection* to a 89 host /host/, optionally on port /port/, from an origin /origin/, with 90 a flag /secure/, and with a particular /resource name/, it must run 91 the following steps: 93 1. If there is no explicit /port/, then: if /secure/ is false, let 94 /port/ be 81, otherwise let /port/ be 815. 96 2. If the user agent is configured to use a proxy to connect to 97 host /host/ and/or port /port/, then connect to that proxy and 98 ask it to open a TCP/IP connection to the host given by /host/ 99 and the port given by /port/. 101 EXAMPLE: For example, if the user agent uses an HTTP proxy 102 for all traffic, then if it was to try to connect to port 80 103 on server example.com, it might send the following lines to 104 the proxy server: 106 CONNECT example.com HTTP/1.1 108 If there was a password, the connection might look like: 110 CONNECT example.com HTTP/1.1 111 Proxy-authorization: Basic ZWRuYW1vZGU6bm9jYXBlcyE= 113 Otherwise, if the user agent is not configured to use a proxy, 114 then open a TCP/IP connection to the host given by /host/ and 115 the port given by /port/. 117 3. If the connection could not be opened, then fail the Web Socket 118 connection and abort these steps. 120 4. If /secure/ is true, perform a TLS handshake over the 121 connection. If this fails (e.g. the server's certificate could 122 not be verified), then fail the Web Socket connection and abort 123 these steps. Otherwise, all further communication on this 124 channel must run through the encrypted tunnel. [RFC2246] 126 5. Send the following bytes to the remote side (the server): 128 47 45 54 20 130 Send the /resource name/ value, encoded as US-ASCII. 132 Send the following bytes: 134 20 48 54 54 50 2f 31 2e 31 0d 0a 55 70 67 72 61 135 64 65 3a 20 57 65 62 53 6f 63 6b 65 74 0d 0a 43 136 6f 6e 6e 65 63 74 69 6f 6e 3a 20 55 70 67 72 61 137 64 65 0d 0a 139 NOTE: The string "GET ", the path, " HTTP/1.1", CRLF, the string 140 "Upgrade: WebSocket", CRLF, and the string "Connection: 141 Upgrade", CRLF. 143 6. Send the following bytes: 145 48 6f 73 74 3a 20 147 Send the /host/ value, encoded as US-ASCII and converted to 148 lowercase, if it represents a host name (and not an IP address). 150 Send the following bytes: 152 0d 0a 154 NOTE: The string "Host: ", the host, and CRLF. 156 7. Send the following bytes: 158 4f 72 69 67 69 6e 3a 20 160 Send the /origin/ value, encoded as US-ASCII and converted to 161 lowercase. 163 Send the following bytes: 165 0d 0a 167 NOTE: The string "Origin: ", the origin, and CRLF. 169 8. If the client has any authentication information or cookies that 170 would be relevant to a resource accessed over HTTP, if /secure/ 171 is false, or HTTPS, if it is true, on host /host/, port /port/, 172 with /resource name/ as the path (and possibly query 173 parameters), then HTTP headers that would be appropriate for 174 that information should be sent at this point. [RFC2616] 175 [RFC2109] [RFC2965] 177 Each header must be on a line of its own (each ending with a CR 178 LF sequence). For the purposes of this step, each header must 179 not be split into multiple lines (despite HTTP otherwise 180 allowing this with continuation lines). 182 EXAMPLE: For example, if the server had a username and 183 password that applied to |http://example.com/socket|, and the 184 Web Socket was being opened to |ws://example.com:80/socket|, 185 it could send them: 187 Authorization: Basic d2FsbGU6ZXZl 189 However, it would not send them if the Web Socket was being 190 opened to |ws://example.com/socket|, as that uses a different 191 port (81, not 80). 193 9. Send the following bytes: 195 0d 0a 197 NOTE: Just a CRLF (a blank line). 199 10. Read the first 85 bytes from the server. If the connection 200 closes before 85 bytes are received, or if the first 85 bytes 201 aren't exactly equal to the following bytes, then fail the Web 202 Socket connection and abort these steps. 204 48 54 54 50 2f 31 2e 31 20 31 30 31 20 57 65 62 205 20 53 6f 63 6b 65 74 20 50 72 6f 74 6f 63 6f 6c 206 20 48 61 6e 64 73 68 61 6b 65 0d 0a 55 70 67 72 207 61 64 65 3a 20 57 65 62 53 6f 63 6b 65 74 0d 0a 208 43 6f 6e 6e 65 63 74 69 6f 6e 3a 20 55 70 67 72 209 61 64 65 0d 0a 211 NOTE: The string "HTTP/1.1 101 Web Socket Protocol Handshake", 212 CRLF, the string "Upgrade: WebSocket", CRLF, the string 213 "Connection: Upgrade", CRLF. 215 11. Let /headers/ be a list of name-value pairs, initially empty. 217 12. _Header_: Let /name/ and /value/ be empty byte arrays. 219 13. Read a byte from the server. 221 If the connection closes before this byte is received, then fail 222 the Web Socket connection and abort these steps. 224 Otherwise, handle the byte as described in the appropriate entry 225 below: 227 -> If the byte is 0x0d (ASCII CR) 228 If the /name/ byte array is empty, then jump to the headers 229 processing step. Otherwise, fail the Web Socket connection 230 and abort these steps. 232 -> If the byte is 0x0a (ASCII LF) 233 Fail the Web Socket connection and abort these steps. 235 -> If the byte is 0x3a (ASCII ":") 236 Move on to the next step. 238 -> If the byte is in the range 0x41 .. 0x5a (ASCII "A" .. "Z") 239 Append a byte whose value is the byte's value plus 0x20 to 240 the /name/ byte array and redo this step for the next byte. 242 -> Otherwise 243 Append the byte to the /name/ byte array and redo this step 244 for the next byte. 246 NOTE: This reads a header name, terminated by a colon, 247 converting upper-case ASCII letters to lowercase, and aborting 248 if a stray CR or LF is found. 250 14. Read a byte from the server. 252 If the connection closes before this byte is received, then fail 253 the Web Socket connection and abort these steps. 255 Otherwise, handle the byte as described in the appropriate entry 256 below: 258 -> If the byte is 0x20 (ASCII space) 259 Ignore the byte and move on to the next step. 261 -> Otherwise 262 Treat the byte as described by the list in the next step, 263 then move on to that next step for real. 265 NOTE: This skips past a space character after the colon, if 266 necessary. 268 15. Read a byte from the server. 270 If the connection closes before this byte is received, then fail 271 the Web Socket connection and abort these steps. 273 Otherwise, handle the byte as described in the appropriate entry 274 below: 276 -> If the byte is 0x0d (ASCII CR) 277 Move on to the next step. 279 -> If the byte is 0x0a (ASCII LF) 280 Fail the Web Socket connection and abort these steps. 282 -> Otherwise 283 Append the byte to the /name/ byte array and redo this step 284 for the next byte. 286 NOTE: This reads a header value, terminated by a CRLF. 288 16. Read a byte from the server. 290 If the connection closes before this byte is received, or if the 291 byte is not a 0x0a byte (ASCII LF), then fail the Web Socket 292 connection and abort these steps. 294 NOTE: This skips past the LF byte of the CRLF after the header. 296 17. Append an entry to the /headers/ list that has the name given by 297 the string obtained by interpreting the /name/ byte array as a 298 UTF-8 byte stream and the value given by the string obtained by 299 interpreting the /value/ byte array as a UTF-8 byte stream. 301 18. Return to the header step above. 303 19. _Headers processing_: If there is not exactly one entry in the 304 /headers/ list whose name is "websocket-origin", or if there is 305 not exactly one entry in the /headers/ list whose name is 306 "websocket-location", or if there are any entries in the 307 /headers/ list whose names are the empty string, then fail the 308 Web Socket connection and abort these steps. 310 20. Handle each entry in the /headers/ list as follows: 312 -> If the entry's name is "websocket-origin|" 313 If the value is not exactly equal to /origin/, converted to 314 lowercase, then fail the Web Socket connection and abort 315 these steps. 317 -> If the entry's name is "websocket-location|" 318 If the value is not exactly equal to a string consisting of 319 the following components in the same order, then fail the Web 320 Socket connection and abort these steps: 322 1. The string "http" if /secure/ is false and "https" if 323 /secure/ is true 325 2. The three characters "://". 327 3. The value of /host/. 329 4. If /secure/ is false and /port/ is not 81, or if /secure/ 330 is true and /port/ is not 815: a ":" character followed 331 by the value of /port/. 333 5. The value of /resource name/. 335 -> If the entry's name is "set-cookie|" or "set-cookie2|" or 336 another cookie-related header name 337 Handle the cookie as defined by the appropriate spec, with 338 the resource being the one with the host /host/, the port 339 /port/, the path (and possibly query parameters) /resource 340 name/, and the scheme |http| if /secure/ is false and |https| 341 if /secure/ is true. [RFC2109] [RFC2965] 343 -> Any other name 344 Ignore it. 346 21. The *Web Socket connection is established*. Now the user agent 347 must send and receive to and from the connection as described in 348 the next section. 350 To *fail the Web Socket connection*, the user agent must close the 351 Web Socket connection, and may report the problem to the user (which 352 would be especially useful for developers). However, user agents 353 must not convey the failure information to the script that attempted 354 the connection in a way distinguishable from the Web Socket being 355 closed normally. 357 2.2. Data framing 359 Once a Web Socket connection is established, the user agent must run 360 through the following state machine for the bytes sent by the server. 362 1. Try to read a byte from the server. Let /frame type/ be that 363 byte. 365 If no byte could be read because the Web Socket connection is 366 closed, then abort. 368 2. Handle the /frame type/ byte as follows: 370 If the high-order bit of the /frame type/ byte is set (i.e. if 371 /frame type/ _and_ed with 0x80 returns 0x80) 372 Run these steps. If at any point during these steps a read is 373 attempted but fails because the Web Socket connection is 374 closed, then abort. 376 1. Let /length/ be zero. 378 2. _Length_: Read a byte, let /b/ be that byte. 380 3. Let /b_v/ be integer corresponding to the low 7 bits of 381 /b/ (the value you would get by _and_ing /b/ with 0x7f). 383 4. Multiply /length/ by 128, add /b_v/ to that result, and 384 store the final result in /length/. 386 5. If the high-order bit of /b/ is set (i.e. if /b/ _and_ed 387 with 0x80 returns 0x80), then return to the step above 388 labeled _length_. 390 6. Read /length/ bytes. 392 7. Discard the read bytes. 394 If the high-order bit of the /frame type/ byte is _not_ set (i.e. 395 if /frame type/ _and_ed with 0x80 returns 0x00) 396 Run these steps. If at any point during these steps a read is 397 attempted but fails because the Web Socket connection is 398 closed, then abort. 400 1. Let /raw data/ be an empty byte array. 402 2. _Data_: Read a byte, let /b/ be that byte. 404 3. If /b/ is not 0xff, then append /b/ to /raw data/ and 405 return to the previous step (labeled _data_). 407 4. Interpret /raw data/ as a UTF-8 string, and store that 408 string in /data/. 410 5. If /frame type/ is 0x00, then *a message has been 411 received* with text /data/. Otherwise, discard the data. 413 3. Return to the first step to read the next byte. 415 If the user agent is faced with content that is too large to be 416 handled appropriately, then it must fail the Web Socket connection. 418 Once a Web Socket connection is established, the user agent must use 419 the following steps to *send /data/ using the Web Socket*: 421 1. Send a 0x00 byte to the server. 423 2. Encode /data/ using UTF-8 and send the resulting byte stream to 424 the server. 426 3. Send a 0xff byte to the server. 428 3. Server-side requirements 430 _This section only applies to servers._ 432 3.1. Minimal handshake 434 NOTE: This section describes the minimal requirements for a server- 435 side implementation of Web Sockets. 437 Listen on a port for TCP/IP. Upon receiving a connection request, 438 open a connection and send the following bytes back to the client: 440 48 54 54 50 2f 31 2e 31 20 31 30 31 20 57 65 62 441 20 53 6f 63 6b 65 74 20 50 72 6f 74 6f 63 6f 6c 442 20 48 61 6e 64 73 68 61 6b 65 0d 0a 55 70 67 72 443 61 64 65 3a 20 57 65 62 53 6f 63 6b 65 74 0d 0a 444 43 6f 6e 6e 65 63 74 69 6f 6e 3a 20 55 70 67 72 445 61 64 65 0d 0a 447 Send the string "WebSocket-Origin" followed by a U+003A COLON (":") 448 followed by the ASCII serialization of the origin from which the 449 server is willing to accept connections, followed by a CRLF pair 450 (0x0d 0x0a). 452 For instance: 454 WebSocket-Origin: http://example.com 456 Send the string "WebSocket-Location" followed by a U+003A COLON (":") 457 followed by the URL of the Web Socket script, followed by a CRLF pair 458 (0x0d 0x0a). 460 For instance: 462 WebSocket-Location: ws://example.com:80/demo 464 Send another CRLF pair (0x0d 0x0a). 466 Read (and discard) data from the client until four bytes 0x0d 0x0a 467 0x0d 0x0a are read. 469 If the connection isn't dropped at this point, go to the data framing 470 section. 472 3.2. Handshake details 474 The previous section ignores the data that is transmitted by the 475 client during the handshake. 477 The data sent by the client consists of a number of fields separated 478 by CR LF pairs (bytes 0x0d 0x0a). 480 The first field consists of three tokens separated by space 481 characters (byte 0x20). The middle token is the path being opened. 482 If the server supports multiple paths, then the server should echo 483 the value of this field in the initial handshake, as part of the URL 484 given on the |WebSocket-Location| line (after the appropriate scheme 485 and host). 487 The remaining fields consist of name-value pairs, with the name part 488 separated from the value part by a colon and a space (bytes 0x3a 489 0x20). Of these, several are interesting: 491 Host (bytes 48 6f 73 74) 492 The value gives the hostname that the client intended to use when 493 opening the Web Socket. It would be of interest in particular to 494 virtual hosting environments, where one server might serve 495 multiple hosts, and might therefore want to return different data. 497 The right host has to be output as part of the URL given on the 498 |WebSocket-Location| line of the handshake described above, to 499 verify that the server knows that it is really representing that 500 host. 502 Origin (bytes 4f 72 69 67 69 6e) 503 The value gives the scheme, hostname, and port (if it's not the 504 default port for the given scheme) of the page that asked the 505 client to open the Web Socket. It would be interesting if the 506 server's operator had deals with operators of other sites, since 507 the server could then decide how to respond (or indeed, _whether_ 508 to respond) based on which site was requesting a connection. 510 If the server supports connections from more than one origin, then 511 the server should echo the value of this field in the initial 512 handshake, on the |WebSocket-Origin| line. 514 Other fields 515 Other fields can be used, such as "Cookie" or "Authorization", for 516 authentication purposes. 518 3.3. Data framing 520 NOTE: This section only describes how to handle content that this 521 specification allows user agents to send (text). It doesn't handle 522 any arbitrary content in the same way that the requirements on user 523 agents defined earlier handle any content including possible future 524 extensions to the protocols. 526 The server should run through the following steps to process the 527 bytes sent by the client: 529 1. Read a byte from the client. Assuming everything is going 530 according to plan, it will be a 0x00 byte. Behaviour for the 531 server is undefined if the byte is not 0x00. 533 2. Let /raw data/ be an empty byte array. 535 3. _Data_: Read a byte, let /b/ be that byte. 537 4. If /b/ is not 0xff, then append /b/ to /raw data/ and return to 538 the previous step (labeled _data_). 540 5. Interpret /raw data/ as a UTF-8 string, and apply whatever 541 server-specific processing should occur for the resulting string. 543 6. Return to the first step to read the next byte. 545 The server should run through the following steps to send strings to 546 the client: 548 1. Send a 0x00 byte to the client to indicate the start of a string. 550 2. Encode /data/ using UTF-8 and send the resulting byte stream to 551 the client. 553 3. Send a 0xff byte to the client to indicate the end of the 554 message. 556 4. Closing the connection 558 To *close the Web Socket connection*, either the user agent or the 559 server closes the TCP/IP connection. There is no closing handshake. 560 Whether the user agent or the server closes the connection, it is 561 said that the *Web Socket connection is closed*. 563 Servers may close the Web Socket connection whenever desired. 565 User agents should not close the Web Socket connection arbitrarily. 567 5. Security considerations 569 ** ISSUE ** ... 571 6. IANA considerations 573 ** ISSUE ** ...(two URI schemes, two ports, HTTP Upgrade keyword) 575 7. Normative References 577 [HTML5] Hickson, I., "HTML5", January 2009. 579 [RFC2109] Kristol, D. and L. Montulli, "HTTP State Management 580 Mechanism", RFC 2109, February 1997. 582 [RFC2246] Dierks, T. and C. Allen, "The TLS Protocol Version 1.0", 583 RFC 2246, January 1999. 585 [RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H., 586 Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext 587 Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999. 589 [RFC2965] Kristol, D. and L. Montulli, "HTTP State Management 590 Mechanism", RFC 2965, October 2000. 592 Author's Address 594 Ian Hickson 595 Google, Inc. 597 Email: ian@hixie.ch 598 URI: http://ln.hixie.ch/