test-server/test-server.c

   1 /*
   2  * libwebsockets-test-server - libwebsockets test implementation
   3  *
   4  * Copyright (C) 2010-2011 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 <stdio.h>
  23 #include <stdlib.h>
  24 #include <unistd.h>
  25 #include <getopt.h>
  26 #include <string.h>
  27 #include <sys/time.h>
  28 #include <assert.h>
  29 #include <syslog.h>
  30
  31 #include "../lib/libwebsockets.h"
  32
  33 static int close_testing;
  34
  35 #ifdef EXTERNAL_POLL
  36 #ifndef LWS_NO_FORK
  37 #define LWS_NO_FORK
  38 #endif
  39
  40 int max_poll_elements;
  41
  42 struct pollfd *pollfds;
  43 int *fd_lookup;
  44 int count_pollfds;
  45
  46 #endif /* EXTERNAL_POLL */
  47
  48
  49 /*
  50  * This demo server shows how to use libwebsockets for one or more
  51  * websocket protocols in the same server
  52  *
  53  * It defines the following websocket protocols:
  54  *
  55  *  dumb-increment-protocol:  once the socket is opened, an incrementing
  56  *                              ascii string is sent down it every 50ms.
  57  *                              If you send "reset\n" on the websocket, then
  58  *                              the incrementing number is reset to 0.
  59  *
  60  *  lws-mirror-protocol: copies any received packet to every connection also
  61  *                              using this protocol, including the sender
  62  */
  63
  64 enum demo_protocols {
  65         /* always first */
  66         PROTOCOL_HTTP = 0,
  67
  68         PROTOCOL_DUMB_INCREMENT,
  69         PROTOCOL_LWS_MIRROR,
  70
  71         /* always last */
  72         DEMO_PROTOCOL_COUNT
  73 };
  74
  75
  76 #define LOCAL_RESOURCE_PATH INSTALL_DATADIR"/libwebsockets-test-server"
  77
  78 /*
  79  * We take a strict whitelist approach to stop ../ attacks
  80  */
  81
  82 struct serveable {
  83         const char *urlpath;
  84         const char *mimetype;
  85 };
  86
  87 static const struct serveable whitelist[] = {
  88         { "/favicon.ico", "image/x-icon" },
  89         { "/libwebsockets.org-logo.png", "image/png" },
  90
  91         /* last one is the default served if no match */
  92         { "/test.html", "text/html" },
  93 };
  94
  95 /* this protocol server (always the first one) just knows how to do HTTP */
  96
  97 static int callback_http(struct libwebsocket_context *context,
  98                 struct libwebsocket *wsi,
  99                 enum libwebsocket_callback_reasons reason, void *user,
 100                                                            void *in, size_t len)
 101 {
 102 #if 0
 103         char client_name[128];
 104         char client_ip[128];
 105 #endif
 106         char buf[256];
 107         int n;
 108 #ifdef EXTERNAL_POLL
 109         int m;
 110         int fd = (int)(long)user;
 111 #endif
 112
 113         switch (reason) {
 114         case LWS_CALLBACK_HTTP:
 115
 116                 for (n = 0; n < (sizeof(whitelist) / sizeof(whitelist[0]) - 1); n++)
 117                         if (in && strcmp(in, whitelist[n].urlpath) == 0)
 118                                 break;
 119
 120                 sprintf(buf, LOCAL_RESOURCE_PATH"%s", whitelist[n].urlpath);
 121
 122                 if (libwebsockets_serve_http_file(context, wsi, buf, whitelist[n].mimetype))
 123                         lwsl_err("Failed to send HTTP file\n");
 124
 125                 /*
 126                  * notice that the sending of the file completes asynchronously,
 127                  * we'll get a LWS_CALLBACK_HTTP_FILE_COMPLETION callback when
 128                  * it's done
 129                  */
 130
 131                 break;
 132
 133         case LWS_CALLBACK_HTTP_FILE_COMPLETION:
 134 //              lwsl_info("LWS_CALLBACK_HTTP_FILE_COMPLETION seen\n");
 135                 /* kill the connection after we sent one file */
 136                 return 1;
 137
 138         /*
 139          * callback for confirming to continue with client IP appear in
 140          * protocol 0 callback since no websocket protocol has been agreed
 141          * yet.  You can just ignore this if you won't filter on client IP
 142          * since the default uhandled callback return is 0 meaning let the
 143          * connection continue.
 144          */
 145
 146         case LWS_CALLBACK_FILTER_NETWORK_CONNECTION:
 147 #if 0
 148                 libwebsockets_get_peer_addresses((int)(long)user, client_name,
 149                              sizeof(client_name), client_ip, sizeof(client_ip));
 150
 151                 fprintf(stderr, "Received network connect from %s (%s)\n",
 152                                                         client_name, client_ip);
 153 #endif
 154                 /* if we returned non-zero from here, we kill the connection */
 155                 break;
 156
 157 #ifdef EXTERNAL_POLL
 158         /*
 159          * callbacks for managing the external poll() array appear in
 160          * protocol 0 callback
 161          */
 162
 163         case LWS_CALLBACK_ADD_POLL_FD:
 164
 165                 if (count_pollfds >= max_poll_elements) {
 166                         lwsl_err("LWS_CALLBACK_ADD_POLL_FD: too many sockets to track\n");
 167                         return 1;
 168                 }
 169
 170                 fd_lookup[fd] = count_pollfds;
 171                 pollfds[count_pollfds].fd = fd;
 172                 pollfds[count_pollfds].events = (int)(long)len;
 173                 pollfds[count_pollfds++].revents = 0;
 174                 break;
 175
 176         case LWS_CALLBACK_DEL_POLL_FD:
 177                 if (!--count_pollfds)
 178                         break;
 179                 m = fd_lookup[fd];
 180                 /* have the last guy take up the vacant slot */
 181                 pollfds[m] = pollfds[count_pollfds];
 182                 fd_lookup[pollfds[count_pollfds].fd] = m;
 183                 break;
 184
 185         case LWS_CALLBACK_SET_MODE_POLL_FD:
 186                 pollfds[fd_lookup[fd]].events |= (int)(long)len;
 187                 break;
 188
 189         case LWS_CALLBACK_CLEAR_MODE_POLL_FD:
 190                 pollfds[fd_lookup[fd]].events &= ~(int)(long)len;
 191                 break;
 192 #endif
 193
 194         default:
 195                 break;
 196         }
 197
 198         return 0;
 199 }
 200
 201 /*
 202  * this is just an example of parsing handshake headers, you don't need this
 203  * in your code unless you will filter allowing connections by the header
 204  * content
 205  */
 206
 207 static void
 208 dump_handshake_info(struct lws_tokens *lwst)
 209 {
 210         int n;
 211         static const char *token_names[WSI_TOKEN_COUNT] = {
 212                 /*[WSI_TOKEN_GET_URI]           =*/ "GET URI",
 213                 /*[WSI_TOKEN_HOST]              =*/ "Host",
 214                 /*[WSI_TOKEN_CONNECTION]        =*/ "Connection",
 215                 /*[WSI_TOKEN_KEY1]              =*/ "key 1",
 216                 /*[WSI_TOKEN_KEY2]              =*/ "key 2",
 217                 /*[WSI_TOKEN_PROTOCOL]          =*/ "Protocol",
 218                 /*[WSI_TOKEN_UPGRADE]           =*/ "Upgrade",
 219                 /*[WSI_TOKEN_ORIGIN]            =*/ "Origin",
 220                 /*[WSI_TOKEN_DRAFT]             =*/ "Draft",
 221                 /*[WSI_TOKEN_CHALLENGE]         =*/ "Challenge",
 222
 223                 /* new for 04 */
 224                 /*[WSI_TOKEN_KEY]               =*/ "Key",
 225                 /*[WSI_TOKEN_VERSION]           =*/ "Version",
 226                 /*[WSI_TOKEN_SWORIGIN]          =*/ "Sworigin",
 227
 228                 /* new for 05 */
 229                 /*[WSI_TOKEN_EXTENSIONS]        =*/ "Extensions",
 230
 231                 /* client receives these */
 232                 /*[WSI_TOKEN_ACCEPT]            =*/ "Accept",
 233                 /*[WSI_TOKEN_NONCE]             =*/ "Nonce",
 234                 /*[WSI_TOKEN_HTTP]              =*/ "Http",
 235                 /*[WSI_TOKEN_MUXURL]    =*/ "MuxURL",
 236         };
 237
 238         for (n = 0; n < WSI_TOKEN_COUNT; n++) {
 239                 if (lwst[n].token == NULL)
 240                         continue;
 241
 242                 fprintf(stderr, "    %s = %s\n", token_names[n], lwst[n].token);
 243         }
 244 }
 245
 246 /* dumb_increment protocol */
 247
 248 /*
 249  * one of these is auto-created for each connection and a pointer to the
 250  * appropriate instance is passed to the callback in the user parameter
 251  *
 252  * for this example protocol we use it to individualize the count for each
 253  * connection.
 254  */
 255
 256 struct per_session_data__dumb_increment {
 257         int number;
 258 };
 259
 260 static int
 261 callback_dumb_increment(struct libwebsocket_context *context,
 262                         struct libwebsocket *wsi,
 263                         enum libwebsocket_callback_reasons reason,
 264                                                void *user, void *in, size_t len)
 265 {
 266         int n;
 267         unsigned char buf[LWS_SEND_BUFFER_PRE_PADDING + 512 +
 268                                                   LWS_SEND_BUFFER_POST_PADDING];
 269         unsigned char *p = &buf[LWS_SEND_BUFFER_PRE_PADDING];
 270         struct per_session_data__dumb_increment *pss = user;
 271
 272         switch (reason) {
 273
 274         case LWS_CALLBACK_ESTABLISHED:
 275                 lwsl_info("callback_dumb_increment: "
 276                                                  "LWS_CALLBACK_ESTABLISHED\n");
 277                 pss->number = 0;
 278                 break;
 279
 280         /*
 281          * in this protocol, we just use the broadcast action as the chance to
 282          * send our own connection-specific data and ignore the broadcast info
 283          * that is available in the 'in' parameter
 284          */
 285
 286         case LWS_CALLBACK_BROADCAST:
 287                 n = sprintf((char *)p, "%d", pss->number++);
 288                 n = libwebsocket_write(wsi, p, n, LWS_WRITE_TEXT);
 289                 if (n < 0) {
 290                         lwsl_err("ERROR %d writing to socket\n", n);
 291                         return 1;
 292                 }
 293                 if (close_testing && pss->number == 50) {
 294                         lwsl_info("close tesing limit, closing\n");
 295                         libwebsocket_close_and_free_session(context, wsi,
 296                                                        LWS_CLOSE_STATUS_NORMAL);
 297                 }
 298                 break;
 299
 300         case LWS_CALLBACK_RECEIVE:
 301 //              fprintf(stderr, "rx %d\n", (int)len);
 302                 if (len < 6)
 303                         break;
 304                 if (strcmp(in, "reset\n") == 0)
 305                         pss->number = 0;
 306                 break;
 307         /*
 308          * this just demonstrates how to use the protocol filter. If you won't
 309          * study and reject connections based on header content, you don't need
 310          * to handle this callback
 311          */
 312
 313         case LWS_CALLBACK_FILTER_PROTOCOL_CONNECTION:
 314                 dump_handshake_info((struct lws_tokens *)(long)user);
 315                 /* you could return non-zero here and kill the connection */
 316                 break;
 317
 318         default:
 319                 break;
 320         }
 321
 322         return 0;
 323 }
 324
 325
 326 /* lws-mirror_protocol */
 327
 328 #define MAX_MESSAGE_QUEUE 128
 329
 330 struct per_session_data__lws_mirror {
 331         struct libwebsocket *wsi;
 332         int ringbuffer_tail;
 333 };
 334
 335 struct a_message {
 336         void *payload;
 337         size_t len;
 338 };
 339
 340 static struct a_message ringbuffer[MAX_MESSAGE_QUEUE];
 341 static int ringbuffer_head;
 342
 343 static struct libwebsocket *wsi_choked[20];
 344 static int num_wsi_choked;
 345
 346 static int
 347 callback_lws_mirror(struct libwebsocket_context *context,
 348                         struct libwebsocket *wsi,
 349                         enum libwebsocket_callback_reasons reason,
 350                                                void *user, void *in, size_t len)
 351 {
 352         int n;
 353         struct per_session_data__lws_mirror *pss = user;
 354
 355         switch (reason) {
 356
 357         case LWS_CALLBACK_ESTABLISHED:
 358                 lwsl_info("callback_lws_mirror: "
 359                                                  "LWS_CALLBACK_ESTABLISHED\n");
 360                 pss->ringbuffer_tail = ringbuffer_head;
 361                 pss->wsi = wsi;
 362                 break;
 363
 364         case LWS_CALLBACK_SERVER_WRITEABLE:
 365                 if (close_testing)
 366                         break;
 367                 while (pss->ringbuffer_tail != ringbuffer_head) {
 368
 369                         n = libwebsocket_write(wsi, (unsigned char *)
 370                                    ringbuffer[pss->ringbuffer_tail].payload +
 371                                    LWS_SEND_BUFFER_PRE_PADDING,
 372                                    ringbuffer[pss->ringbuffer_tail].len,
 373                                                                 LWS_WRITE_TEXT);
 374                         if (n < 0) {
 375                                 lwsl_err("ERROR %d writing to socket\n", n);
 376                                 return 1;
 377                         }
 378
 379                         if (pss->ringbuffer_tail == (MAX_MESSAGE_QUEUE - 1))
 380                                 pss->ringbuffer_tail = 0;
 381                         else
 382                                 pss->ringbuffer_tail++;
 383
 384                         if (((ringbuffer_head - pss->ringbuffer_tail) &
 385                                   (MAX_MESSAGE_QUEUE - 1)) == (MAX_MESSAGE_QUEUE - 15)) {
 386                                 for (n = 0; n < num_wsi_choked; n++)
 387                                         libwebsocket_rx_flow_control(wsi_choked[n], 1);
 388                                 num_wsi_choked = 0;
 389                         }
 390                         // lwsl_debug("tx fifo %d\n", (ringbuffer_head - pss->ringbuffer_tail) & (MAX_MESSAGE_QUEUE - 1));
 391
 392                         if (lws_send_pipe_choked(wsi)) {
 393                                 libwebsocket_callback_on_writable(context, wsi);
 394                                 return 0;
 395                         }
 396                 }
 397                 break;
 398
 399         case LWS_CALLBACK_BROADCAST:
 400                 n = libwebsocket_write(wsi, in, len, LWS_WRITE_TEXT);
 401                 if (n < 0)
 402                         lwsl_err("mirror write failed\n");
 403                 break;
 404
 405         case LWS_CALLBACK_RECEIVE:
 406
 407                 if (((ringbuffer_head - pss->ringbuffer_tail) &
 408                                   (MAX_MESSAGE_QUEUE - 1)) == (MAX_MESSAGE_QUEUE - 1)) {
 409                         lwsl_err("dropping!\n");
 410                         goto choke;
 411                 }
 412
 413                 if (ringbuffer[ringbuffer_head].payload)
 414                         free(ringbuffer[ringbuffer_head].payload);
 415
 416                 ringbuffer[ringbuffer_head].payload =
 417                                 malloc(LWS_SEND_BUFFER_PRE_PADDING + len +
 418                                                   LWS_SEND_BUFFER_POST_PADDING);
 419                 ringbuffer[ringbuffer_head].len = len;
 420                 memcpy((char *)ringbuffer[ringbuffer_head].payload +
 421                                           LWS_SEND_BUFFER_PRE_PADDING, in, len);
 422                 if (ringbuffer_head == (MAX_MESSAGE_QUEUE - 1))
 423                         ringbuffer_head = 0;
 424                 else
 425                         ringbuffer_head++;
 426
 427                 if (((ringbuffer_head - pss->ringbuffer_tail) &
 428                                   (MAX_MESSAGE_QUEUE - 1)) != (MAX_MESSAGE_QUEUE - 2))
 429                         goto done;
 430
 431 choke:
 432                 if (num_wsi_choked < sizeof wsi_choked / sizeof wsi_choked[0]) {
 433                         libwebsocket_rx_flow_control(wsi, 0);
 434                         wsi_choked[num_wsi_choked++] = wsi;
 435                 }
 436
 437 //              lwsl_debug("rx fifo %d\n", (ringbuffer_head - pss->ringbuffer_tail) & (MAX_MESSAGE_QUEUE - 1));
 438 done:
 439                 libwebsocket_callback_on_writable_all_protocol(
 440                                                libwebsockets_get_protocol(wsi));
 441                 break;
 442
 443         /*
 444          * this just demonstrates how to use the protocol filter. If you won't
 445          * study and reject connections based on header content, you don't need
 446          * to handle this callback
 447          */
 448
 449         case LWS_CALLBACK_FILTER_PROTOCOL_CONNECTION:
 450                 dump_handshake_info((struct lws_tokens *)(long)user);
 451                 /* you could return non-zero here and kill the connection */
 452                 break;
 453
 454         default:
 455                 break;
 456         }
 457
 458         return 0;
 459 }
 460
 461
 462 /* list of supported protocols and callbacks */
 463
 464 static struct libwebsocket_protocols protocols[] = {
 465         /* first protocol must always be HTTP handler */
 466
 467         {
 468                 "http-only",            /* name */
 469                 callback_http,          /* callback */
 470                 0                       /* per_session_data_size */
 471         },
 472         {
 473                 "dumb-increment-protocol",
 474                 callback_dumb_increment,
 475                 sizeof(struct per_session_data__dumb_increment),
 476         },
 477         {
 478                 "lws-mirror-protocol",
 479                 callback_lws_mirror,
 480                 sizeof(struct per_session_data__lws_mirror)
 481         },
 482         {
 483                 NULL, NULL, 0           /* End of list */
 484         }
 485 };
 486
 487 static struct option options[] = {
 488         { "help",       no_argument,            NULL, 'h' },
 489         { "debug",      required_argument,      NULL, 'd' },
 490         { "port",       required_argument,      NULL, 'p' },
 491         { "ssl",        no_argument,            NULL, 's' },
 492         { "interface",  required_argument,      NULL, 'i' },
 493         { "closetest",  no_argument,            NULL, 'c' },
 494 #ifndef LWS_NO_DAEMONIZE
 495         { "daemonize",  no_argument,            NULL, 'D' },
 496 #endif
 497         { NULL, 0, 0, 0 }
 498 };
 499
 500 int main(int argc, char **argv)
 501 {
 502         int n = 0;
 503         const char *cert_path =
 504                             LOCAL_RESOURCE_PATH"/libwebsockets-test-server.pem";
 505         const char *key_path =
 506                         LOCAL_RESOURCE_PATH"/libwebsockets-test-server.key.pem";
 507         unsigned char buf[LWS_SEND_BUFFER_PRE_PADDING + 1024 +
 508                                                   LWS_SEND_BUFFER_POST_PADDING];
 509         int port = 7681;
 510         int use_ssl = 0;
 511         struct libwebsocket_context *context;
 512         int opts = 0;
 513         char interface_name[128] = "";
 514         const char *interface = NULL;
 515         int syslog_options = LOG_PID | LOG_PERROR;
 516 #ifdef LWS_NO_FORK
 517         unsigned int oldus = 0;
 518 #endif
 519         int debug_level = 7;
 520 #ifndef LWS_NO_DAEMONIZE
 521         int daemonize = 0;
 522 #endif
 523
 524         while (n >= 0) {
 525                 n = getopt_long(argc, argv, "ci:hsp:d:D", options, NULL);
 526                 if (n < 0)
 527                         continue;
 528                 switch (n) {
 529 #ifndef LWS_NO_DAEMONIZE
 530                 case 'D':
 531                         daemonize = 1;
 532                         syslog_options &= ~LOG_PERROR;
 533                         break;
 534 #endif
 535                 case 'd':
 536                         debug_level = atoi(optarg);
 537                         break;
 538                 case 's':
 539                         use_ssl = 1;
 540                         break;
 541                 case 'p':
 542                         port = atoi(optarg);
 543                         break;
 544                 case 'i':
 545                         strncpy(interface_name, optarg, sizeof interface_name);
 546                         interface_name[(sizeof interface_name) - 1] = '\0';
 547                         interface = interface_name;
 548                         break;
 549                 case 'c':
 550                         close_testing = 1;
 551                         fprintf(stderr, " Close testing mode -- closes on "
 552                                            "client after 50 dumb increments"
 553                                            "and suppresses lws_mirror spam\n");
 554                         break;
 555                 case 'h':
 556                         fprintf(stderr, "Usage: test-server "
 557                                         "[--port=<p>] [--ssl] "
 558                                         "[-d <log bitfield>]\n");
 559                         exit(1);
 560                 }
 561         }
 562
 563 #ifndef LWS_NO_DAEMONIZE
 564         /*
 565          * normally lock path would be /var/lock/lwsts or similar, to
 566          * simplify getting started without having to take care about
 567          * permissions or running as root, set to /tmp/.lwsts-lock
 568          */
 569         if (daemonize && lws_daemonize("/tmp/.lwsts-lock")) {
 570                 fprintf(stderr, "Failed to daemonize\n");
 571                 return 1;
 572         }
 573 #endif
 574         /* we will only try to log things according to our debug_level */
 575         setlogmask(LOG_UPTO (LOG_DEBUG));
 576         openlog("lwsts", syslog_options, LOG_DAEMON);
 577
 578         /* tell the library what debug level to emit and to send it to syslog */
 579         lws_set_log_level(debug_level, lwsl_emit_syslog);
 580
 581         lwsl_notice("libwebsockets test server - "
 582                         "(C) Copyright 2010-2013 Andy Green <andy@warmcat.com> - "
 583                                                     "licensed under LGPL2.1\n");
 584         if (!use_ssl)
 585                 cert_path = key_path = NULL;
 586 #ifdef EXTERNAL_POLL
 587         max_poll_elements = getdtablesize();
 588         pollfds = malloc(max_poll_elements * sizeof (struct pollfd));
 589         fd_lookup = malloc(max_poll_elements * sizeof (int));
 590         if (pollfds == NULL || fd_lookup == NULL) {
 591                 lwsl_err("Out of memory pollfds=%d\n", max_poll_elements);
 592                 return -1;
 593         }
 594 #endif
 595
 596         context = libwebsocket_create_context(port, interface, protocols,
 597 #ifndef LWS_NO_EXTENSIONS
 598                                 libwebsocket_internal_extensions,
 599 #else
 600                                 NULL,
 601 #endif
 602                                 cert_path, key_path, NULL, -1, -1, opts, NULL);
 603         if (context == NULL) {
 604                 lwsl_err("libwebsocket init failed\n");
 605                 return -1;
 606         }
 607
 608         buf[LWS_SEND_BUFFER_PRE_PADDING] = 'x';
 609
 610 #ifdef LWS_NO_FORK
 611
 612         /*
 613          * This example shows how to work with no forked service loop
 614          */
 615
 616         lwsl_info(" Using no-fork service loop\n");
 617
 618         n = 0;
 619         while (n >= 0) {
 620                 struct timeval tv;
 621
 622                 gettimeofday(&tv, NULL);
 623
 624                 /*
 625                  * This broadcasts to all dumb-increment-protocol connections
 626                  * at 20Hz.
 627                  *
 628                  * We're just sending a character 'x', in these examples the
 629                  * callbacks send their own per-connection content.
 630                  *
 631                  * You have to send something with nonzero length to get the
 632                  * callback actions delivered.
 633                  *
 634                  * We take care of pre-and-post padding allocation.
 635                  */
 636
 637                 if (((unsigned int)tv.tv_usec - oldus) > 50000) {
 638                         libwebsockets_broadcast(
 639                                         &protocols[PROTOCOL_DUMB_INCREMENT],
 640                                         &buf[LWS_SEND_BUFFER_PRE_PADDING], 1);
 641                         oldus = tv.tv_usec;
 642                 }
 643
 644                 /*
 645                  * This example server does not fork or create a thread for
 646                  * websocket service, it all runs in this single loop.  So,
 647                  * we have to give the websockets an opportunity to service
 648                  * "manually".
 649                  *
 650                  * If no socket is needing service, the call below returns
 651                  * immediately and quickly.  Negative return means we are
 652                  * in process of closing
 653                  */
 654 #ifdef EXTERNAL_POLL
 655
 656                 /*
 657                  * this represents an existing server's single poll action
 658                  * which also includes libwebsocket sockets
 659                  */
 660
 661                 n = poll(pollfds, count_pollfds, 50);
 662                 if (n < 0)
 663                         continue;
 664
 665
 666                 if (n)
 667                         for (n = 0; n < count_pollfds; n++)
 668                                 if (pollfds[n].revents)
 669                                         /*
 670                                         * returns immediately if the fd does not
 671                                         * match anything under libwebsockets
 672                                         * control
 673                                         */
 674                                         if (libwebsocket_service_fd(context,
 675                                                                   &pollfds[n]) < 0)
 676                                                 goto done;
 677 #else
 678                 n = libwebsocket_service(context, 50);
 679 #endif
 680         }
 681
 682 #else /* !LWS_NO_FORK */
 683
 684         /*
 685          * This example shows how to work with the forked websocket service loop
 686          */
 687
 688         lwsl_info(" Using forked service loop\n");
 689
 690         /*
 691          * This forks the websocket service action into a subprocess so we
 692          * don't have to take care about it.
 693          */
 694
 695         n = libwebsockets_fork_service_loop(context);
 696         if (n < 0) {
 697                 lwsl_err("Unable to fork service loop %d\n", n);
 698                 return 1;
 699         }
 700         if (n)
 701                 exit(0);
 702
 703         while (1) {
 704
 705                 usleep(50000);
 706
 707                 /*
 708                  * This broadcasts to all dumb-increment-protocol connections
 709                  * at 20Hz.
 710                  *
 711                  * We're just sending a character 'x', in these examples the
 712                  * callbacks send their own per-connection content.
 713                  *
 714                  * You have to send something with nonzero length to get the
 715                  * callback actions delivered.
 716                  *
 717                  * We take care of pre-and-post padding allocation.
 718                  */
 719
 720                 libwebsockets_broadcast_foreign(&protocols[PROTOCOL_DUMB_INCREMENT],
 721                                         &buf[LWS_SEND_BUFFER_PRE_PADDING], 1);
 722         }
 723
 724 #endif
 725 #ifdef EXTERNAL_POLL
 726 done:
 727 #endif
 728
 729         libwebsocket_context_destroy(context);
 730
 731         lwsl_notice("libwebsockets-test-server exited cleanly\n");
 732
 733         closelog();
 734
 735         return 0;
 736 }