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