lib/client.c

   1 /*
   2  * libwebsockets - small server side websockets and web server implementation
   3  *
   4  * Copyright (C) 2010-2013 Andy Green <andy@warmcat.com>
   5  *
   6  *  This library is free software; you can redistribute it and/or
   7  *  modify it under the terms of the GNU Lesser General Public
   8  *  License as published by the Free Software Foundation:
   9  *  version 2.1 of the License.
  10  *
  11  *  This library is distributed in the hope that it will be useful,
  12  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  *  Lesser General Public License for more details.
  15  *
  16  *  You should have received a copy of the GNU Lesser General Public
  17  *  License along with this library; if not, write to the Free Software
  18  *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
  19  *  MA  02110-1301  USA
  20  */
  21
  22 #include "private-libwebsockets.h"
  23
  24 #ifdef WIN32
  25 #include <tchar.h>
  26 #include <io.h>
  27 #else
  28 #ifdef LWS_BUILTIN_GETIFADDRS
  29 #include <getifaddrs.h>
  30 #else
  31 #include <ifaddrs.h>
  32 #endif
  33 #include <sys/un.h>
  34 #include <sys/socket.h>
  35 #include <netdb.h>
  36 #endif
  37
  38 #ifdef LWS_OPENSSL_SUPPORT
  39 extern int openssl_websocket_private_data_index;
  40 #endif
  41
  42 int lws_client_socket_service(struct libwebsocket_context *context, struct libwebsocket *wsi, struct pollfd *pollfd)
  43 {
  44         int n;
  45         char pkt[1024];
  46         char *p = &pkt[0];
  47         int len;
  48         char c;
  49 #ifdef LWS_OPENSSL_SUPPORT
  50         char ssl_err_buf[512];
  51 #endif
  52
  53         switch (wsi->mode) {
  54
  55         case LWS_CONNMODE_WS_CLIENT_WAITING_PROXY_REPLY:
  56
  57                 /* handle proxy hung up on us */
  58
  59                 if (pollfd->revents & (POLLERR | POLLHUP)) {
  60
  61                         lwsl_warn("Proxy connection %p (fd=%d) dead\n",
  62                                 (void *)wsi, pollfd->fd);
  63
  64                         libwebsocket_close_and_free_session(context, wsi,
  65                                                      LWS_CLOSE_STATUS_NOSTATUS);
  66                         return 0;
  67                 }
  68
  69                 n = recv(wsi->sock, pkt, sizeof pkt, 0);
  70                 if (n < 0) {
  71                         libwebsocket_close_and_free_session(context, wsi,
  72                                                      LWS_CLOSE_STATUS_NOSTATUS);
  73                         lwsl_err("ERROR reading from proxy socket\n");
  74                         return 0;
  75                 }
  76
  77                 pkt[13] = '\0';
  78                 if (strcmp(pkt, "HTTP/1.0 200 ") != 0) {
  79                         libwebsocket_close_and_free_session(context, wsi,
  80                                                      LWS_CLOSE_STATUS_NOSTATUS);
  81                         lwsl_err("ERROR from proxy: %s\n", pkt);
  82                         return 0;
  83                 }
  84
  85                 /* clear his proxy connection timeout */
  86
  87                 libwebsocket_set_timeout(wsi, NO_PENDING_TIMEOUT, 0);
  88
  89                 /* fallthru */
  90
  91         case LWS_CONNMODE_WS_CLIENT_ISSUE_HANDSHAKE:
  92
  93                 /*
  94                  * we are under PENDING_TIMEOUT_SENT_CLIENT_HANDSHAKE
  95                  * timeout protection set in client-handshake.c
  96                  */
  97
  98         #ifdef LWS_OPENSSL_SUPPORT
  99
 100                 /*
 101                  * take care of our libwebsocket_callback_on_writable
 102                  * happening at a time when there's no real connection yet
 103                  */
 104
 105                 pollfd->events &= ~POLLOUT;
 106
 107                 /* external POLL support via protocol 0 */
 108                 context->protocols[0].callback(context, wsi,
 109                         LWS_CALLBACK_CLEAR_MODE_POLL_FD,
 110                         (void *)(long)wsi->sock, NULL, POLLOUT);
 111
 112                 /* we can retry this... so just cook the SSL BIO the first time */
 113
 114                 if (wsi->use_ssl && !wsi->ssl) {
 115
 116                         wsi->ssl = SSL_new(context->ssl_client_ctx);
 117                         wsi->client_bio = BIO_new_socket(wsi->sock,
 118                                                                    BIO_NOCLOSE);
 119
 120                         SSL_set_bio(wsi->ssl, wsi->client_bio, wsi->client_bio);
 121
 122                         BIO_set_nbio(wsi->client_bio, 1); /* nonblocking */
 123
 124                         SSL_set_ex_data(wsi->ssl,
 125                                         openssl_websocket_private_data_index,
 126                                                                        context);
 127                 }
 128
 129                 if (wsi->use_ssl) {
 130                         lws_latency_pre(context, wsi);
 131                         n = SSL_connect(wsi->ssl);
 132                         lws_latency(context, wsi, "SSL_connect LWS_CONNMODE_WS_CLIENT_ISSUE_HANDSHAKE", n, n > 0);
 133
 134                         if (n < 0) {
 135                                 n = SSL_get_error(wsi->ssl, n);
 136
 137                                 if (n == SSL_ERROR_WANT_READ ||
 138                                         n == SSL_ERROR_WANT_WRITE) {
 139                                         /*
 140                                          * wants us to retry connect due to state of the
 141                                          * underlying ssl layer... but since it may be
 142                                          * stalled on blocked write, no incoming data may
 143                                          * arrive to trigger the retry.  Force (possibly
 144                                          * many if the SSL state persists in returning the
 145                                          * condition code, but other sockets are getting
 146                                          * serviced inbetweentimes) us to get called back
 147                                          * when writable.
 148                                          */
 149
 150                                         lwsl_info("SSL_connect -> SSL_ERROR_WANT_... retrying\n");
 151                                         libwebsocket_callback_on_writable(context, wsi);
 152
 153                                         return 0; /* no error */
 154                                 }
 155                                 n = -1;
 156                         }
 157
 158                         if (n <= 0) {
 159                                 /*
 160                                  * retry if new data comes until we
 161                                  * run into the connection timeout or win
 162                                  */
 163
 164                                 lwsl_err("SSL connect error %s\n",
 165                                         ERR_error_string(ERR_get_error(),
 166                                                                   ssl_err_buf));
 167                                 return 0;
 168                         }
 169
 170                         lws_latency_pre(context, wsi);
 171                         n = SSL_get_verify_result(wsi->ssl);
 172                         lws_latency(context, wsi, "SSL_get_verify_result LWS_CONNMODE_WS_CLIENT_ISSUE_HANDSHAKE", n, n > 0);
 173                         if ((n != X509_V_OK) && (
 174                                 n != X509_V_ERR_DEPTH_ZERO_SELF_SIGNED_CERT ||
 175                                                            wsi->use_ssl != 2)) {
 176
 177                                 lwsl_err("server's cert didn't "
 178                                                            "look good %d\n", n);
 179                                 libwebsocket_close_and_free_session(context,
 180                                                 wsi, LWS_CLOSE_STATUS_NOSTATUS);
 181                                 return 0;
 182                         }
 183                 } else
 184                         wsi->ssl = NULL;
 185         #endif
 186
 187                 p = libwebsockets_generate_client_handshake(context, wsi, p);
 188                 if (p == NULL) {
 189                         lwsl_err("Failed to generate handshake for client, closing it\n");
 190                         libwebsocket_close_and_free_session(context, wsi,
 191                                                      LWS_CLOSE_STATUS_NOSTATUS);
 192                         return 0;
 193                 }
 194
 195                 /* send our request to the server */
 196
 197                 lws_latency_pre(context, wsi);
 198         #ifdef LWS_OPENSSL_SUPPORT
 199                 if (wsi->use_ssl)
 200                         n = SSL_write(wsi->ssl, pkt, p - pkt);
 201                 else
 202         #endif
 203                         n = send(wsi->sock, pkt, p - pkt, 0);
 204                 lws_latency(context, wsi, "send or SSL_write LWS_CONNMODE_WS_CLIENT_ISSUE_HANDSHAKE", n, n >= 0);
 205
 206                 if (n < 0) {
 207                         lwsl_debug("ERROR writing to client socket\n");
 208                         libwebsocket_close_and_free_session(context, wsi,
 209                                                      LWS_CLOSE_STATUS_NOSTATUS);
 210                         return 0;
 211                 }
 212
 213                 wsi->u.hdr.parser_state = WSI_TOKEN_NAME_PART;
 214                 wsi->u.hdr.lextable_pos = 0;
 215                 wsi->mode = LWS_CONNMODE_WS_CLIENT_WAITING_SERVER_REPLY;
 216                 libwebsocket_set_timeout(wsi,
 217                                 PENDING_TIMEOUT_AWAITING_SERVER_RESPONSE, AWAITING_TIMEOUT);
 218
 219                 break;
 220
 221         case LWS_CONNMODE_WS_CLIENT_WAITING_SERVER_REPLY:
 222
 223                 /* handle server hung up on us */
 224
 225                 if (pollfd->revents & (POLLERR | POLLHUP)) {
 226
 227                         lwsl_debug("Server connection %p (fd=%d) dead\n",
 228                                 (void *)wsi, pollfd->fd);
 229
 230                         goto bail3;
 231                 }
 232
 233
 234                 /* interpret the server response */
 235
 236                 /*
 237                  *  HTTP/1.1 101 Switching Protocols
 238                  *  Upgrade: websocket
 239                  *  Connection: Upgrade
 240                  *  Sec-WebSocket-Accept: me89jWimTRKTWwrS3aRrL53YZSo=
 241                  *  Sec-WebSocket-Nonce: AQIDBAUGBwgJCgsMDQ4PEC==
 242                  *  Sec-WebSocket-Protocol: chat
 243                  */
 244
 245                 /*
 246                  * we have to take some care here to only take from the
 247                  * socket bytewise.  The browser may (and has been seen to
 248                  * in the case that onopen() performs websocket traffic)
 249                  * coalesce both handshake response and websocket traffic
 250                  * in one packet, since at that point the connection is
 251                  * definitively ready from browser pov.
 252                  */
 253
 254                 len = 1;
 255                 while (wsi->u.hdr.parser_state != WSI_PARSING_COMPLETE && len > 0) {
 256 #ifdef LWS_OPENSSL_SUPPORT
 257                         if (wsi->use_ssl)
 258                                 len = SSL_read(wsi->ssl, &c, 1);
 259                          else
 260 #endif
 261                                 len = recv(wsi->sock, &c, 1, 0);
 262
 263                         libwebsocket_parse(wsi, c);
 264                 }
 265
 266                 /*
 267                  * hs may also be coming in multiple packets, there is a 5-sec
 268                  * libwebsocket timeout still active here too, so if parsing did
 269                  * not complete just wait for next packet coming in this state
 270                  */
 271
 272                 if (wsi->u.hdr.parser_state != WSI_PARSING_COMPLETE)
 273                         break;
 274
 275                 /*
 276                  * otherwise deal with the handshake.  If there's any
 277                  * packet traffic already arrived we'll trigger poll() again
 278                  * right away and deal with it that way
 279                  */
 280
 281                 return lws_client_interpret_server_handshake(context, wsi);
 282
 283 bail3:
 284                 if (wsi->c_protocol)
 285                         free(wsi->c_protocol);
 286                 libwebsocket_close_and_free_session(context, wsi,
 287                                                     LWS_CLOSE_STATUS_NOSTATUS);
 288                 return 0;
 289
 290         case LWS_CONNMODE_WS_CLIENT_WAITING_EXTENSION_CONNECT:
 291                 lwsl_ext("LWS_CONNMODE_WS_CLIENT_WAITING_EXTENSION_CONNECT\n");
 292                 break;
 293
 294         case LWS_CONNMODE_WS_CLIENT_PENDING_CANDIDATE_CHILD:
 295                 lwsl_ext("LWS_CONNMODE_WS_CLIENT_PENDING_CANDIDATE_CHILD\n");
 296                 break;
 297         default:
 298                 break;
 299         }
 300
 301         return 0;
 302 }
 303
 304
 305 /*
 306  * In-place str to lower case
 307  */
 308
 309 static void
 310 strtolower(char *s)
 311 {
 312         while (*s) {
 313                 *s = tolower(*s);
 314                 s++;
 315         }
 316 }
 317
 318 int
 319 lws_client_interpret_server_handshake(struct libwebsocket_context *context,
 320                 struct libwebsocket *wsi)
 321 {
 322         const char *pc;
 323         int okay = 0;
 324 #ifndef LWS_NO_EXTENSIONS
 325         char ext_name[128];
 326         struct libwebsocket_extension *ext;
 327         void *v;
 328         int more = 1;
 329         const char *c;
 330 #endif
 331         int n;
 332
 333         /*
 334          * well, what the server sent looked reasonable for syntax.
 335          * Now let's confirm it sent all the necessary headers
 336          */
 337 #if 0
 338         lwsl_parser("WSI_TOKEN_HTTP: %d\n",
 339                                     wsi->utf8_token[WSI_TOKEN_HTTP].token_len);
 340         lwsl_parser("WSI_TOKEN_UPGRADE: %d\n",
 341                                  wsi->utf8_token[WSI_TOKEN_UPGRADE].token_len);
 342         lwsl_parser("WSI_TOKEN_CONNECTION: %d\n",
 343                               wsi->utf8_token[WSI_TOKEN_CONNECTION].token_len);
 344         lwsl_parser("WSI_TOKEN_ACCEPT: %d\n",
 345                                   wsi->utf8_token[WSI_TOKEN_ACCEPT].token_len);
 346         lwsl_parser("WSI_TOKEN_NONCE: %d\n",
 347                                    wsi->utf8_token[WSI_TOKEN_NONCE].token_len);
 348         lwsl_parser("WSI_TOKEN_PROTOCOL: %d\n",
 349                                 wsi->utf8_token[WSI_TOKEN_PROTOCOL].token_len);
 350 #endif
 351
 352         strtolower(wsi->utf8_token[WSI_TOKEN_HTTP].token);
 353         if (strncmp(wsi->utf8_token[WSI_TOKEN_HTTP].token, "101", 3)) {
 354                 lwsl_warn("libwebsocket_client_handshake "
 355                                 "server sent bad HTTP response '%s'\n",
 356                                  wsi->utf8_token[WSI_TOKEN_HTTP].token);
 357                 goto bail3;
 358         }
 359
 360         strtolower(wsi->utf8_token[WSI_TOKEN_UPGRADE].token);
 361         if (strcmp(wsi->utf8_token[WSI_TOKEN_UPGRADE].token,
 362                                                          "websocket")) {
 363                 lwsl_warn("libwebsocket_client_handshake server "
 364                                 "sent bad Upgrade header '%s'\n",
 365                                   wsi->utf8_token[WSI_TOKEN_UPGRADE].token);
 366                 goto bail3;
 367         }
 368
 369         strtolower(wsi->utf8_token[WSI_TOKEN_CONNECTION].token);
 370         if (strcmp(wsi->utf8_token[WSI_TOKEN_CONNECTION].token,
 371                                                            "upgrade")) {
 372                 lwsl_warn("libwebsocket_client_handshake server "
 373                                 "sent bad Connection hdr '%s'\n",
 374                            wsi->utf8_token[WSI_TOKEN_CONNECTION].token);
 375                 goto bail3;
 376         }
 377
 378         pc = wsi->c_protocol;
 379         if (pc == NULL)
 380                 lwsl_parser("lws_client_interpret_server_handshake: "
 381                                                           "NULL c_protocol\n");
 382         else
 383                 lwsl_parser("lws_client_interpret_server_handshake: "
 384                                                       "cPprotocol='%s'\n", pc);
 385
 386         /*
 387          * confirm the protocol the server wants to talk was in the list
 388          * of protocols we offered
 389          */
 390
 391         if (!wsi->utf8_token[WSI_TOKEN_PROTOCOL].token_len) {
 392
 393                 lwsl_info("lws_client_interpret_server_handshake "
 394                                                "WSI_TOKEN_PROTOCOL is null\n");
 395                 /*
 396                  * no protocol name to work from,
 397                  * default to first protocol
 398                  */
 399                 wsi->protocol = &context->protocols[0];
 400                 wsi->c_callback = wsi->protocol->callback;
 401                 free(wsi->c_protocol);
 402
 403                 goto check_extensions;
 404         }
 405
 406         while (*pc && !okay) {
 407                 if ((!strncmp(pc, wsi->utf8_token[WSI_TOKEN_PROTOCOL].token,
 408                  wsi->utf8_token[WSI_TOKEN_PROTOCOL].token_len)) &&
 409                  (pc[wsi->utf8_token[WSI_TOKEN_PROTOCOL].token_len] == ',' ||
 410                   pc[wsi->utf8_token[WSI_TOKEN_PROTOCOL].token_len] == '\0')) {
 411                         okay = 1;
 412                         continue;
 413                 }
 414                 while (*pc && *pc != ',')
 415                         pc++;
 416                 while (*pc && *pc != ' ')
 417                         pc++;
 418         }
 419
 420         /* done with him now */
 421
 422         if (wsi->c_protocol)
 423                 free(wsi->c_protocol);
 424
 425         if (!okay) {
 426                 lwsl_err("libwebsocket_client_handshake server "
 427                                         "sent bad protocol '%s'\n",
 428                                  wsi->utf8_token[WSI_TOKEN_PROTOCOL].token);
 429                 goto bail2;
 430         }
 431
 432         /*
 433          * identify the selected protocol struct and set it
 434          */
 435         n = 0;
 436         wsi->protocol = NULL;
 437         while (context->protocols[n].callback && !wsi->protocol) {  /* Stop after finding first one?? */
 438                 if (strcmp(wsi->utf8_token[WSI_TOKEN_PROTOCOL].token,
 439                                            context->protocols[n].name) == 0) {
 440                         wsi->protocol = &context->protocols[n];
 441                         wsi->c_callback = wsi->protocol->callback;
 442                 }
 443                 n++;
 444         }
 445
 446         if (wsi->protocol == NULL) {
 447                 lwsl_err("libwebsocket_client_handshake server "
 448                                 "requested protocol '%s', which we "
 449                                 "said we supported but we don't!\n",
 450                                  wsi->utf8_token[WSI_TOKEN_PROTOCOL].token);
 451                 goto bail2;
 452         }
 453
 454
 455 check_extensions:
 456 #ifndef LWS_NO_EXTENSIONS
 457         /* instantiate the accepted extensions */
 458
 459         if (!wsi->utf8_token[WSI_TOKEN_EXTENSIONS].token_len) {
 460                 lwsl_ext("no client extenstions allowed by server\n");
 461                 goto check_accept;
 462         }
 463
 464         /*
 465          * break down the list of server accepted extensions
 466          * and go through matching them or identifying bogons
 467          */
 468
 469         c = wsi->utf8_token[WSI_TOKEN_EXTENSIONS].token;
 470         n = 0;
 471         while (more) {
 472
 473                 if (*c && (*c != ',' && *c != ' ' && *c != '\t')) {
 474                         ext_name[n] = *c++;
 475                         if (n < sizeof(ext_name) - 1)
 476                                 n++;
 477                         continue;
 478                 }
 479                 ext_name[n] = '\0';
 480                 if (!*c)
 481                         more = 0;
 482                 else {
 483                         c++;
 484                         if (!n)
 485                                 continue;
 486                 }
 487
 488                 /* check we actually support it */
 489
 490                 lwsl_ext("checking client ext %s\n", ext_name);
 491
 492                 n = 0;
 493                 ext = wsi->protocol->owning_server->extensions;
 494                 while (ext && ext->callback) {
 495
 496                         if (strcmp(ext_name, ext->name)) {
 497                                 ext++;
 498                                 continue;
 499                         }
 500
 501                         n = 1;
 502
 503                         lwsl_ext("instantiating client ext %s\n", ext_name);
 504
 505                         /* instantiate the extension on this conn */
 506
 507                         wsi->active_extensions_user[
 508                                 wsi->count_active_extensions] =
 509                                          malloc(ext->per_session_data_size);
 510                         if (wsi->active_extensions_user[
 511                                 wsi->count_active_extensions] == NULL) {
 512                                 lwsl_err("Out of mem\n");
 513                                 goto bail2;
 514                         }
 515                         memset(wsi->active_extensions_user[
 516                                 wsi->count_active_extensions], 0,
 517                                                     ext->per_session_data_size);
 518                         wsi->active_extensions[
 519                                   wsi->count_active_extensions] = ext;
 520
 521                         /* allow him to construct his context */
 522
 523                         ext->callback(wsi->protocol->owning_server,
 524                                 ext, wsi,
 525                                    LWS_EXT_CALLBACK_CLIENT_CONSTRUCT,
 526                                         wsi->active_extensions_user[
 527                                          wsi->count_active_extensions],
 528                                                                    NULL, 0);
 529
 530                         wsi->count_active_extensions++;
 531
 532                         ext++;
 533                 }
 534
 535                 if (n == 0) {
 536                         lwsl_warn("Server said we should use"
 537                                   "an unknown extension '%s'!\n", ext_name);
 538                         goto bail2;
 539                 }
 540
 541                 n = 0;
 542         }
 543
 544 check_accept:
 545 #endif
 546
 547         /*
 548          * Confirm his accept token is the one we precomputed
 549          */
 550
 551         if (strcmp(wsi->utf8_token[WSI_TOKEN_ACCEPT].token,
 552                                   wsi->u.hdr.initial_handshake_hash_base64)) {
 553                 lwsl_warn("libwebsocket_client_handshake server "
 554                         "sent bad ACCEPT '%s' vs computed '%s'\n",
 555                         wsi->utf8_token[WSI_TOKEN_ACCEPT].token,
 556                                         wsi->u.hdr.initial_handshake_hash_base64);
 557                 goto bail2;
 558         }
 559
 560         /* allocate the per-connection user memory (if any) */
 561         if (wsi->protocol->per_session_data_size &&
 562                                           !libwebsocket_ensure_user_space(wsi))
 563                 goto bail2;
 564
 565         /* clear his proxy connection timeout */
 566
 567         libwebsocket_set_timeout(wsi, NO_PENDING_TIMEOUT, 0);
 568
 569         /* mark him as being alive */
 570
 571         wsi->state = WSI_STATE_ESTABLISHED;
 572         wsi->mode = LWS_CONNMODE_WS_CLIENT;
 573
 574         /* union transition */
 575         memset(&wsi->u, 0, sizeof wsi->u);
 576
 577         lwsl_debug("handshake OK for protocol %s\n", wsi->protocol->name);
 578
 579         /* call him back to inform him he is up */
 580
 581         wsi->protocol->callback(context, wsi,
 582                                 LWS_CALLBACK_CLIENT_ESTABLISHED,
 583                                                      wsi->user_space, NULL, 0);
 584 #ifndef LWS_NO_EXTENSIONS
 585         /*
 586          * inform all extensions, not just active ones since they
 587          * already know
 588          */
 589
 590         ext = context->extensions;
 591
 592         while (ext && ext->callback) {
 593                 v = NULL;
 594                 for (n = 0; n < wsi->count_active_extensions; n++)
 595                         if (wsi->active_extensions[n] == ext)
 596                                 v = wsi->active_extensions_user[n];
 597
 598                 ext->callback(context, ext, wsi,
 599                           LWS_EXT_CALLBACK_ANY_WSI_ESTABLISHED, v, NULL, 0);
 600                 ext++;
 601         }
 602 #endif
 603
 604         return 0;
 605
 606 bail3:
 607         if (wsi->c_protocol)
 608                 free(wsi->c_protocol);
 609
 610 bail2:
 611         if (wsi->c_callback) wsi->c_callback(context, wsi,
 612        LWS_CALLBACK_CLIENT_CONNECTION_ERROR,
 613                          wsi->user_space,
 614                          NULL, 0);
 615         libwebsocket_close_and_free_session(context, wsi,
 616                                                  LWS_CLOSE_STATUS_NOSTATUS);  // But this should be LWS_CLOSE_STATUS_PROTOCOL_ERR
 617
 618         return 1;
 619 }
 620
 621
 622 char *
 623 libwebsockets_generate_client_handshake(struct libwebsocket_context *context,
 624                 struct libwebsocket *wsi, char *pkt)
 625 {
 626         char hash[20];
 627         char key_b64[40];
 628         char *p = pkt;
 629         int n;
 630 #ifndef LWS_NO_EXTENSIONS
 631         struct libwebsocket_extension *ext;
 632         struct libwebsocket_extension *ext1;
 633         int ext_count = 0;
 634 #endif
 635         unsigned char buf[LWS_SEND_BUFFER_PRE_PADDING + 1 +
 636                          MAX_USER_RX_BUFFER + LWS_SEND_BUFFER_POST_PADDING];
 637         static const char magic_websocket_guid[] =
 638                                          "258EAFA5-E914-47DA-95CA-C5AB0DC85B11";
 639
 640         /*
 641          * create the random key
 642          */
 643
 644         n = libwebsockets_get_random(context, hash, 16);
 645         if (n != 16) {
 646                 lwsl_err("Unable to read from random dev %s\n",
 647                                                 SYSTEM_RANDOM_FILEPATH);
 648                 free(wsi->c_path);
 649                 free(wsi->c_host);
 650                 if (wsi->c_origin)
 651                         free(wsi->c_origin);
 652                 if (wsi->c_protocol)
 653                         free(wsi->c_protocol);
 654                 libwebsocket_close_and_free_session(context, wsi,
 655                                              LWS_CLOSE_STATUS_NOSTATUS);
 656                 return NULL;
 657         }
 658
 659         lws_b64_encode_string(hash, 16, key_b64, sizeof key_b64);
 660
 661         /*
 662          * 00 example client handshake
 663          *
 664          * GET /socket.io/websocket HTTP/1.1
 665          * Upgrade: WebSocket
 666          * Connection: Upgrade
 667          * Host: 127.0.0.1:9999
 668          * Origin: http://127.0.0.1
 669          * Sec-WebSocket-Key1: 1 0 2#0W 9 89 7  92 ^
 670          * Sec-WebSocket-Key2: 7 7Y 4328 B2v[8(z1
 671          * Cookie: socketio=websocket
 672          *
 673          * (Á®Ä0¶†≥
 674          *
 675          * 04 example client handshake
 676          *
 677          * GET /chat HTTP/1.1
 678          * Host: server.example.com
 679          * Upgrade: websocket
 680          * Connection: Upgrade
 681          * Sec-WebSocket-Key: dGhlIHNhbXBsZSBub25jZQ==
 682          * Sec-WebSocket-Origin: http://example.com
 683          * Sec-WebSocket-Protocol: chat, superchat
 684          * Sec-WebSocket-Version: 4
 685          */
 686
 687         p += sprintf(p, "GET %s HTTP/1.1\x0d\x0a", wsi->c_path);
 688
 689         p += sprintf(p, "Pragma: no-cache\x0d\x0a"
 690                                         "Cache-Control: no-cache\x0d\x0a");
 691
 692         p += sprintf(p, "Host: %s\x0d\x0a", wsi->c_host);
 693         p += sprintf(p, "Upgrade: websocket\x0d\x0a"
 694                                         "Connection: Upgrade\x0d\x0a"
 695                                         "Sec-WebSocket-Key: ");
 696         strcpy(p, key_b64);
 697         p += strlen(key_b64);
 698         p += sprintf(p, "\x0d\x0a");
 699         if (wsi->c_origin) {
 700                 if (wsi->ietf_spec_revision == 13)
 701                         p += sprintf(p, "Origin: %s\x0d\x0a", wsi->c_origin);
 702                 else
 703                         p += sprintf(p, "Sec-WebSocket-Origin: %s\x0d\x0a",
 704                                                          wsi->c_origin);
 705         }
 706         if (wsi->c_protocol)
 707                 p += sprintf(p, "Sec-WebSocket-Protocol: %s\x0d\x0a",
 708                                                        wsi->c_protocol);
 709
 710         /* tell the server what extensions we could support */
 711
 712         p += sprintf(p, "Sec-WebSocket-Extensions: ");
 713 #ifndef LWS_NO_EXTENSIONS
 714         ext = context->extensions;
 715         while (ext && ext->callback) {
 716
 717                 n = 0;
 718                 ext1 = context->extensions;
 719
 720                 while (ext1 && ext1->callback) {
 721                         n |= ext1->callback(context, ext1, wsi,
 722                                 LWS_EXT_CALLBACK_CHECK_OK_TO_PROPOSE_EXTENSION,
 723                                         NULL, (char *)ext->name, 0);
 724
 725                         ext1++;
 726                 }
 727
 728                 if (n) { /* an extension vetos us */
 729                         lwsl_ext("ext %s vetoed\n", (char *)ext->name);
 730                         ext++;
 731                         continue;
 732                 }
 733
 734                 n = context->protocols[0].callback(context, wsi,
 735                         LWS_CALLBACK_CLIENT_CONFIRM_EXTENSION_SUPPORTED,
 736                                 wsi->user_space, (char *)ext->name, 0);
 737
 738                 /*
 739                  * zero return from callback means
 740                  * go ahead and allow the extension,
 741                  * it's what we get if the callback is
 742                  * unhandled
 743                  */
 744
 745                 if (n) {
 746                         ext++;
 747                         continue;
 748                 }
 749
 750                 /* apply it */
 751
 752                 if (ext_count)
 753                         *p++ = ',';
 754                 p += sprintf(p, "%s", ext->name);
 755                 ext_count++;
 756
 757                 ext++;
 758         }
 759 #endif
 760         p += sprintf(p, "\x0d\x0a");
 761
 762         if (wsi->ietf_spec_revision)
 763                 p += sprintf(p, "Sec-WebSocket-Version: %d\x0d\x0a",
 764                                                wsi->ietf_spec_revision);
 765
 766         /* give userland a chance to append, eg, cookies */
 767
 768         context->protocols[0].callback(context, wsi,
 769                 LWS_CALLBACK_CLIENT_APPEND_HANDSHAKE_HEADER,
 770                 NULL, &p, (pkt + sizeof(pkt)) - p - 12);
 771
 772         p += sprintf(p, "\x0d\x0a");
 773
 774         /* prepare the expected server accept response */
 775
 776         strcpy((char *)buf, key_b64);
 777         strcpy((char *)&buf[strlen((char *)buf)], magic_websocket_guid);
 778
 779         SHA1(buf, strlen((char *)buf), (unsigned char *)hash);
 780
 781         lws_b64_encode_string(hash, 20,
 782                         wsi->u.hdr.initial_handshake_hash_base64,
 783                              sizeof wsi->u.hdr.initial_handshake_hash_base64);
 784
 785         /* done with these now */
 786
 787         free(wsi->c_path);
 788         free(wsi->c_host);
 789         if (wsi->c_origin)
 790                 free(wsi->c_origin);
 791
 792         return p;
 793 }
 794