lib/client-handshake.c

   1 #include "private-libwebsockets.h"
   2 #include <netdb.h>
   3
   4
   5 /*
   6  * In-place str to lower case
   7  */
   8
   9 void
  10 strtolower(char *s)
  11 {
  12         while (*s) {
  13                 *s = tolower(*s);
  14                 s++;
  15         }
  16 }
  17
  18 void
  19 libwebsocket_client_close(struct libwebsocket *wsi)
  20 {
  21         int n = wsi->state;
  22         struct libwebsocket_context *clients;
  23
  24         if (n == WSI_STATE_DEAD_SOCKET)
  25                 return;
  26
  27         /* mark the WSI as dead and let the callback know */
  28
  29         wsi->state = WSI_STATE_DEAD_SOCKET;
  30
  31         if (wsi->protocol) {
  32                 if (wsi->protocol->callback && n == WSI_STATE_ESTABLISHED)
  33                         wsi->protocol->callback(wsi, LWS_CALLBACK_CLOSED,
  34                                                       wsi->user_space, NULL, 0);
  35
  36                 /* remove it from the client polling list */
  37                 clients = wsi->protocol->owning_server;
  38                 if (clients)
  39                         for (n = 0; n < clients->fds_count; n++) {
  40                                 if (clients->wsi[n] != wsi)
  41                                         continue;
  42                                 while (n < clients->fds_count - 1) {
  43                                         clients->fds[n] = clients->fds[n + 1];
  44                                         clients->wsi[n] = clients->wsi[n + 1];
  45                                         n++;
  46                                 }
  47                                 /* we only have to deal with one */
  48                                 n = clients->fds_count;
  49                         }
  50
  51         }
  52
  53         /* clean out any parsing allocations */
  54
  55         for (n = 0; n < WSI_TOKEN_COUNT; n++)
  56                 if (wsi->utf8_token[n].token)
  57                         free(wsi->utf8_token[n].token);
  58
  59         /* shut down reasonably cleanly */
  60
  61 #ifdef LWS_OPENSSL_SUPPORT
  62         if (wsi->ssl) {
  63                 n = SSL_get_fd(wsi->ssl);
  64                 SSL_shutdown(wsi->ssl);
  65                 close(n);
  66                 SSL_free(wsi->ssl);
  67         } else {
  68 #endif
  69                 shutdown(wsi->sock, SHUT_RDWR);
  70                 close(wsi->sock);
  71 #ifdef LWS_OPENSSL_SUPPORT
  72         }
  73 #endif
  74 }
  75
  76
  77 /**
  78  * libwebsocket_client_connect() - Connect to another websocket server
  79  * @this:       Websocket context
  80  * @address:    Remote server address, eg, "myserver.com"
  81  * @port:       Port to connect to on the remote server, eg, 80
  82  * @ssl_connection:     0 = ws://, 1 = wss:// encrypted, 2 = wss:// allow self
  83  *                      signed certs
  84  * @path:       Websocket path on server
  85  * @host:       Hostname on server
  86  * @origin:     Socket origin name
  87  * @protocol:   Comma-separated list of protocols being asked for from
  88  *              the server, or just one.  The server will pick the one it
  89  *              likes best.
  90  *
  91  *      This function creates a connection to a remote server
  92  */
  93
  94 struct libwebsocket *
  95 libwebsocket_client_connect(struct libwebsocket_context *this,
  96                               const char *address,
  97                               int port,
  98                               int ssl_connection,
  99                               const char *path,
 100                               const char *host,
 101                               const char *origin,
 102                               const char *protocol)
 103 {
 104         struct hostent *server_hostent;
 105         struct sockaddr_in server_addr;
 106         char buf[150];
 107         char key_b64[150];
 108         char hash[20];
 109         int fd;
 110         struct pollfd pfd;
 111         static const char magic_websocket_guid[] =
 112                                          "258EAFA5-E914-47DA-95CA-C5AB0DC85B11";
 113         static const char magic_websocket_04_masking_guid[] =
 114                                          "61AC5F19-FBBA-4540-B96F-6561F1AB40A8";
 115         char pkt[1024];
 116         char *p = &pkt[0];
 117         const char *pc;
 118         int len;
 119         int okay = 0;
 120         struct libwebsocket *wsi;
 121         int n;
 122         int plen = 0;
 123 #ifdef LWS_OPENSSL_SUPPORT
 124         char ssl_err_buf[512];
 125 #else
 126         if (ssl_connection) {
 127                 fprintf(stderr, "libwebsockets not configured for ssl\n");
 128                 return NULL;
 129         }
 130 #endif
 131
 132         wsi = malloc(sizeof(struct libwebsocket));
 133         if (wsi == NULL) {
 134                 fprintf(stderr, "Out of memory allocing new connection\n");
 135                 return NULL;
 136         }
 137
 138         this->wsi[this->fds_count] = wsi;
 139
 140         wsi->ietf_spec_revision = 4;
 141         wsi->name_buffer_pos = 0;
 142         wsi->user_space = NULL;
 143         wsi->state = WSI_STATE_CLIENT_UNCONNECTED;
 144         wsi->pings_vs_pongs = 0;
 145         wsi->protocol = NULL;
 146
 147         for (n = 0; n < WSI_TOKEN_COUNT; n++) {
 148                 wsi->utf8_token[n].token = NULL;
 149                 wsi->utf8_token[n].token_len = 0;
 150         }
 151
 152         /*
 153          * proxy?
 154          */
 155
 156         if (this->http_proxy_port) {
 157                 plen = sprintf(pkt, "CONNECT %s:%u HTTP/1.0\x0d\x0a"
 158                         "User-agent: libwebsockets\x0d\x0a"
 159 /*Proxy-authorization: basic aGVsbG86d29ybGQ= */
 160                         "\x0d\x0a", address, port);
 161
 162                 /* OK from now on we talk via the proxy */
 163
 164                 address = this->http_proxy_address;
 165                 port = this->http_proxy_port;
 166         }
 167
 168         /*
 169          * prepare the actual connection (to the proxy, if any)
 170          */
 171
 172         server_hostent = gethostbyname(address);
 173         if (server_hostent == NULL) {
 174                 fprintf(stderr, "Unable to get host name from %s\n", address);
 175                 goto bail1;
 176         }
 177
 178         wsi->sock = socket(AF_INET, SOCK_STREAM, 0);
 179
 180         if (wsi->sock < 0) {
 181                 fprintf(stderr, "Unable to open socket\n");
 182                 goto bail1;
 183         }
 184
 185
 186         server_addr.sin_family = AF_INET;
 187         server_addr.sin_port = htons(port);
 188         server_addr.sin_addr = *((struct in_addr *)server_hostent->h_addr);
 189         bzero(&server_addr.sin_zero, 8);
 190
 191         if (connect(wsi->sock, (struct sockaddr *)&server_addr,
 192                                               sizeof(struct sockaddr)) == -1)  {
 193                 fprintf(stderr, "Connect failed\n");
 194                 goto bail1;
 195         }
 196
 197         /* we are connected to server, or proxy */
 198
 199         if (this->http_proxy_port) {
 200
 201                 n = send(wsi->sock, pkt, plen, 0);
 202                 if (n < 0) {
 203                         close(wsi->sock);
 204                         fprintf(stderr, "ERROR writing to proxy socket\n");
 205                         goto bail1;
 206                 }
 207
 208                 pfd.fd = wsi->sock;
 209                 pfd.events = POLLIN;
 210                 pfd.revents = 0;
 211
 212                 n = poll(&pfd, 1, 5000);
 213                 if (n <= 0) {
 214                         close(wsi->sock);
 215                         fprintf(stderr, "libwebsocket_client_handshake "
 216                                         "timeout on proxy response");
 217                         goto bail1;
 218                 }
 219
 220                 n = recv(wsi->sock, pkt, sizeof pkt, 0);
 221                 if (n < 0) {
 222                         close(wsi->sock);
 223                         fprintf(stderr, "ERROR reading from proxy socket\n");
 224                         goto bail1;
 225                 }
 226
 227                 pkt[13] = '\0';
 228                 if (strcmp(pkt, "HTTP/1.0 200 ") != 0) {
 229                         close(wsi->sock);
 230                         fprintf(stderr, "ERROR from proxy: %s\n", pkt);
 231                         goto bail1;
 232                 }
 233
 234                 /* we can just start sending to proxy */
 235         }
 236
 237 #ifdef LWS_OPENSSL_SUPPORT
 238         if (ssl_connection) {
 239
 240                 wsi->ssl = SSL_new(this->ssl_client_ctx);
 241                 wsi->client_bio = BIO_new_socket(wsi->sock, BIO_NOCLOSE);
 242                 SSL_set_bio(wsi->ssl, wsi->client_bio, wsi->client_bio);
 243
 244                 if (SSL_connect(wsi->ssl) <= 0) {
 245                         fprintf(stderr, "SSL connect error %s\n",
 246                                 ERR_error_string(ERR_get_error(), ssl_err_buf));
 247                         goto bail1;
 248                 }
 249
 250                 n = SSL_get_verify_result(wsi->ssl);
 251                 if (n != X509_V_OK) {
 252                         if (n != X509_V_ERR_DEPTH_ZERO_SELF_SIGNED_CERT ||
 253                                                           ssl_connection != 2) {
 254
 255                                 fprintf(stderr, "server's cert didn't "
 256                                                            "look good %d\n", n);
 257                                 goto bail2;
 258                         }
 259                 }
 260         } else {
 261                 wsi->ssl = NULL;
 262 #endif
 263
 264
 265 #ifdef LWS_OPENSSL_SUPPORT
 266         }
 267 #endif
 268
 269         /*
 270          * create the random key
 271          */
 272
 273         fd = open(SYSTEM_RANDOM_FILEPATH, O_RDONLY);
 274         if (fd < 1) {
 275                 fprintf(stderr, "Unable to open random device %s\n",
 276                                                         SYSTEM_RANDOM_FILEPATH);
 277                 goto bail2;
 278         }
 279         n = read(fd, hash, 16);
 280         if (n != 16) {
 281                 fprintf(stderr, "Unable to read from random device %s\n",
 282                                                         SYSTEM_RANDOM_FILEPATH);
 283                 close(fd);
 284                 goto bail2;
 285         }
 286         close(fd);
 287
 288         lws_b64_encode_string(hash, 16, key_b64, sizeof key_b64);
 289
 290         /*
 291          * 04 example client handshake
 292          *
 293          * GET /chat HTTP/1.1
 294          * Host: server.example.com
 295          * Upgrade: websocket
 296          * Connection: Upgrade
 297          * Sec-WebSocket-Key: dGhlIHNhbXBsZSBub25jZQ==
 298          * Sec-WebSocket-Origin: http://example.com
 299          * Sec-WebSocket-Protocol: chat, superchat
 300          * Sec-WebSocket-Version: 4
 301          */
 302
 303          p += sprintf(p, "GET %s HTTP/1.1\x0d\x0a", path);
 304          p += sprintf(p, "Host: %s\x0d\x0a", host);
 305          p += sprintf(p, "Upgrade: websocket\x0d\x0a");
 306          p += sprintf(p, "Connection: Upgrade\x0d\x0aSec-WebSocket-Key: ");
 307          strcpy(p, key_b64);
 308          p += strlen(key_b64);
 309          p += sprintf(p, "\x0d\x0aSec-WebSocket-Origin: %s\x0d\x0a", origin);
 310          if (protocol != NULL)
 311                 p += sprintf(p, "Sec-WebSocket-Protocol: %s\x0d\x0a", protocol);
 312          p += sprintf(p, "Sec-WebSocket-Version: 4\x0d\x0a\x0d\x0a");
 313
 314
 315         /* prepare the expected server accept response */
 316
 317         strcpy(buf, key_b64);
 318         strcpy(&buf[strlen(buf)], magic_websocket_guid);
 319
 320         SHA1((unsigned char *)buf, strlen(buf), (unsigned char *)hash);
 321
 322         lws_b64_encode_string(hash, 20, wsi->initial_handshake_hash_base64,
 323                                   sizeof wsi->initial_handshake_hash_base64);
 324
 325         /* send our request to the server */
 326
 327 #ifdef LWS_OPENSSL_SUPPORT
 328         if (ssl_connection)
 329                 n = SSL_write(wsi->ssl, pkt, p - pkt);
 330         else
 331 #endif
 332                 n = send(wsi->sock, pkt, p - pkt, 0);
 333
 334         if (n < 0) {
 335                 fprintf(stderr, "ERROR writing to client socket\n");
 336                 goto bail2;
 337         }
 338
 339         wsi->parser_state = WSI_TOKEN_NAME_PART;
 340
 341         pfd.fd = wsi->sock;
 342         pfd.events = POLLIN;
 343         pfd.revents = 0;
 344
 345         n = poll(&pfd, 1, 5000);
 346         if (n < 0) {
 347                 fprintf(stderr, "libwebsocket_client_handshake socket error "
 348                                 "while waiting for handshake response");
 349                 goto bail2;
 350         }
 351         if (n == 0) {
 352                 fprintf(stderr, "libwebsocket_client_handshake timeout "
 353                                 "while waiting for handshake response");
 354                 goto bail2;
 355         }
 356
 357         /* interpret the server response */
 358
 359         /*
 360          *  HTTP/1.1 101 Switching Protocols
 361          *  Upgrade: websocket
 362          *  Connection: Upgrade
 363          *  Sec-WebSocket-Accept: me89jWimTRKTWwrS3aRrL53YZSo=
 364          *  Sec-WebSocket-Nonce: AQIDBAUGBwgJCgsMDQ4PEC==
 365          *  Sec-WebSocket-Protocol: chat
 366          */
 367
 368 #ifdef LWS_OPENSSL_SUPPORT
 369         if (ssl_connection)
 370                 len = SSL_read(wsi->ssl, pkt, sizeof pkt);
 371         else
 372 #endif
 373                 len = recv(wsi->sock, pkt, sizeof pkt, 0);
 374
 375         if (len < 0) {
 376                 fprintf(stderr, "libwebsocket_client_handshake read error\n");
 377                 goto bail2;
 378         }
 379
 380         p = pkt;
 381         for (n = 0; n < len; n++)
 382                 libwebsocket_parse(wsi, *p++);
 383
 384         if (wsi->parser_state != WSI_PARSING_COMPLETE) {
 385                 fprintf(stderr, "libwebsocket_client_handshake server response"
 386                                 " failed parsing\n");
 387                 goto bail2;
 388         }
 389
 390         /*
 391          * well, what the server sent looked reasonable for syntax.
 392          * Now let's confirm it sent all the necessary headers
 393          */
 394
 395          if (!wsi->utf8_token[WSI_TOKEN_HTTP].token_len ||
 396                         !wsi->utf8_token[WSI_TOKEN_UPGRADE].token_len ||
 397                         !wsi->utf8_token[WSI_TOKEN_CONNECTION].token_len ||
 398                         !wsi->utf8_token[WSI_TOKEN_ACCEPT].token_len ||
 399                         !wsi->utf8_token[WSI_TOKEN_NONCE].token_len ||
 400                         (!wsi->utf8_token[WSI_TOKEN_PROTOCOL].token_len &&
 401                                                             protocol != NULL)) {
 402                 fprintf(stderr, "libwebsocket_client_handshake "
 403                                                 "missing required header(s)\n");
 404                 pkt[len] = '\0';
 405                 fprintf(stderr, "%s", pkt);
 406                 goto bail2;
 407         }
 408
 409         /*
 410          * Everything seems to be there, now take a closer look at what is in
 411          * each header
 412          */
 413
 414         strtolower(wsi->utf8_token[WSI_TOKEN_HTTP].token);
 415         if (strcmp(wsi->utf8_token[WSI_TOKEN_HTTP].token,
 416                                                    "101 switching protocols")) {
 417                 fprintf(stderr, "libwebsocket_client_handshake server sent bad"
 418                                 " HTTP response '%s'\n",
 419                                          wsi->utf8_token[WSI_TOKEN_HTTP].token);
 420                 goto bail2;
 421         }
 422
 423         strtolower(wsi->utf8_token[WSI_TOKEN_UPGRADE].token);
 424         if (strcmp(wsi->utf8_token[WSI_TOKEN_UPGRADE].token, "websocket")) {
 425                 fprintf(stderr, "libwebsocket_client_handshake server sent bad"
 426                                 " Upgrade header '%s'\n",
 427                                       wsi->utf8_token[WSI_TOKEN_UPGRADE].token);
 428                 goto bail2;
 429         }
 430
 431         strtolower(wsi->utf8_token[WSI_TOKEN_CONNECTION].token);
 432         if (strcmp(wsi->utf8_token[WSI_TOKEN_CONNECTION].token, "upgrade")) {
 433                 fprintf(stderr, "libwebsocket_client_handshake server sent bad"
 434                                 " Connection hdr '%s'\n",
 435                                    wsi->utf8_token[WSI_TOKEN_CONNECTION].token);
 436                 goto bail2;
 437         }
 438         /*
 439          * confirm the protocol the server wants to talk was in the list of
 440          * protocols we offered
 441          */
 442
 443         if (!wsi->utf8_token[WSI_TOKEN_PROTOCOL].token_len) {
 444
 445                 /* no protocol name to work from, default to first protocol */
 446                 wsi->protocol = &this->protocols[0];
 447
 448                 goto check_accept;
 449         }
 450
 451         pc = protocol;
 452         while (*pc && !okay) {
 453                 if ((!strncmp(pc, wsi->utf8_token[WSI_TOKEN_PROTOCOL].token,
 454                         wsi->utf8_token[WSI_TOKEN_PROTOCOL].token_len)) &&
 455                 (pc[wsi->utf8_token[WSI_TOKEN_PROTOCOL].token_len] == ',' ||
 456                    pc[wsi->utf8_token[WSI_TOKEN_PROTOCOL].token_len] == '\0')) {
 457                         okay = 1;
 458                         continue;
 459                 }
 460                 while (*pc && *pc != ',')
 461                         pc++;
 462                 while (*pc && *pc != ' ')
 463                         pc++;
 464         }
 465         if (!okay) {
 466                 fprintf(stderr, "libwebsocket_client_handshake server "
 467                                         "sent bad protocol '%s'\n",
 468                              wsi->utf8_token[WSI_TOKEN_PROTOCOL].token);
 469                 goto bail2;
 470         }
 471
 472         /*
 473          * identify the selected protocol struct and set it
 474          */
 475         n = 0;
 476         wsi->protocol = NULL;
 477         while (this->protocols[n].callback) {
 478                 if (strcmp(wsi->utf8_token[WSI_TOKEN_PROTOCOL].token,
 479                                        this->protocols[n].name) == 0)
 480                         wsi->protocol = &this->protocols[n];
 481                 n++;
 482         }
 483
 484         if (wsi->protocol == NULL) {
 485                 fprintf(stderr, "libwebsocket_client_handshake server "
 486                                 "requested protocol '%s', which we "
 487                                 "said we supported but we don't!\n",
 488                              wsi->utf8_token[WSI_TOKEN_PROTOCOL].token);
 489                 goto bail2;
 490         }
 491
 492 check_accept:
 493         /*
 494          * Confirm his accept token is the same as the one we precomputed
 495          */
 496
 497         if (strcmp(wsi->utf8_token[WSI_TOKEN_ACCEPT].token,
 498                                           wsi->initial_handshake_hash_base64)) {
 499                 fprintf(stderr, "libwebsocket_client_handshake server sent "
 500                                 "bad ACCEPT '%s' vs computed '%s'\n",
 501                                 wsi->utf8_token[WSI_TOKEN_ACCEPT].token,
 502                                             wsi->initial_handshake_hash_base64);
 503                 goto bail2;
 504         }
 505
 506         /*
 507          * Calculate the masking key to use when sending data to server
 508          */
 509
 510         strcpy(buf, key_b64);
 511         p = buf + strlen(key_b64);
 512         strcpy(p, wsi->utf8_token[WSI_TOKEN_NONCE].token);
 513         p += wsi->utf8_token[WSI_TOKEN_NONCE].token_len;
 514         strcpy(p, magic_websocket_04_masking_guid);
 515         SHA1((unsigned char *)buf, strlen(buf), wsi->masking_key_04);
 516
 517         /* allocate the per-connection user memory (if any) */
 518
 519         if (wsi->protocol->per_session_data_size) {
 520                 wsi->user_space = malloc(
 521                                   wsi->protocol->per_session_data_size);
 522                 if (wsi->user_space  == NULL) {
 523                         fprintf(stderr, "Out of memory for "
 524                                                    "conn user space\n");
 525                         goto bail2;
 526                 }
 527         } else
 528                 wsi->user_space = NULL;
 529
 530         /* okay he is good to go */
 531
 532         this->fds[this->fds_count].fd = wsi->sock;
 533         this->fds[this->fds_count].revents = 0;
 534         this->fds[this->fds_count++].events = POLLIN;
 535
 536         wsi->state = WSI_STATE_ESTABLISHED;
 537         wsi->mode = LWS_CONNMODE_WS_CLIENT;
 538
 539         fprintf(stderr, "handshake OK for protocol %s\n", wsi->protocol->name);
 540
 541         /* call him back to inform him he is up */
 542
 543         wsi->protocol->callback(wsi,
 544                          LWS_CALLBACK_CLIENT_ESTABLISHED,
 545                          wsi->user_space,
 546                          NULL, 0);
 547         return wsi;
 548
 549
 550 bail2:
 551         libwebsocket_client_close(wsi);
 552 bail1:
 553         free(wsi);
 554
 555         return NULL;
 556 }