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
  30 #include "../lib/libwebsockets.h"
  31
  32 static int close_testing;
  33
  34 #ifdef EXTERNAL_POLL
  35 #define LWS_NO_FORK
  36 #ifndef MAX_CLIENTS
  37 #define MAX_POLL_ELEMENTS 100
  38 #else
  39 #define MAX_POLL_ELEMENTS (MAX_CLIENTS)
  40 #endif
  41
  42 struct poll_hash_map {
  43         int fd;
  44         int index;
  45 };
  46
  47 #define POLL_HASH_BITS 8
  48
  49 #define POLL_HASH_BUCKETS (1 << POLL_HASH_BITS)
  50 #define POLL_ENTRIES_PER_BUCKET (MAX_POLL_ELEMENTS / (1 << (POLL_HASH_BITS - 2)))
  51 #define POLL_HASH(num) (num & (POLL_HASH_BUCKETS - 1))
  52
  53 struct pollfd pollfds[MAX_POLL_ELEMENTS];
  54 struct poll_hash_map pollfd_maps[POLL_HASH_BUCKETS][POLL_ENTRIES_PER_BUCKET];
  55 int pollfd_count[POLL_HASH_BUCKETS];
  56 int count_pollfds = 0;
  57
  58 static int find_poll_map_index(int hash, int fd)
  59 {
  60         int n;
  61
  62         for (n = 0; n < pollfd_count[hash]; n++)
  63                 if (pollfd_maps[hash][n].fd == fd)
  64                         return n;
  65
  66         return -1;
  67 }
  68
  69 static int find_pollfd_index(int fd)
  70 {
  71         int n;
  72         int hash = POLL_HASH(fd);
  73
  74         n = find_poll_map_index(hash, fd);
  75         if (n < 0)
  76                 return n;
  77
  78         return pollfd_maps[hash][n].index;
  79 }
  80
  81 #endif /* EXTERNAL_POLL */
  82
  83 /*
  84  * This demo server shows how to use libwebsockets for one or more
  85  * websocket protocols in the same server
  86  *
  87  * It defines the following websocket protocols:
  88  *
  89  *  dumb-increment-protocol:  once the socket is opened, an incrementing
  90  *                              ascii string is sent down it every 50ms.
  91  *                              If you send "reset\n" on the websocket, then
  92  *                              the incrementing number is reset to 0.
  93  *
  94  *  lws-mirror-protocol: copies any received packet to every connection also
  95  *                              using this protocol, including the sender
  96  */
  97
  98 enum demo_protocols {
  99         /* always first */
 100         PROTOCOL_HTTP = 0,
 101
 102         PROTOCOL_DUMB_INCREMENT,
 103         PROTOCOL_LWS_MIRROR,
 104
 105         /* always last */
 106         DEMO_PROTOCOL_COUNT
 107 };
 108
 109
 110 #define LOCAL_RESOURCE_PATH INSTALL_DATADIR"/libwebsockets-test-server"
 111
 112 /*
 113  * We take a strict whitelist approach to stop ../ attacks
 114  */
 115
 116 struct serveable {
 117         const char *urlpath;
 118         const char *mimetype;
 119 };
 120
 121 static const struct serveable whitelist[] = {
 122         { "/favicon.ico", "image/x-icon" },
 123         { "/libwebsockets.org-logo.png", "image/png" },
 124
 125         /* last one is the default served if no match */
 126         { "/test.html", "text/html" },
 127 };
 128
 129 /* this protocol server (always the first one) just knows how to do HTTP */
 130
 131 static int callback_http(struct libwebsocket_context *context,
 132                 struct libwebsocket *wsi,
 133                 enum libwebsocket_callback_reasons reason, void *user,
 134                                                            void *in, size_t len)
 135 {
 136         char client_name[128];
 137         char client_ip[128];
 138         char buf[256];
 139         int n;
 140 #ifdef EXTERNAL_POLL
 141         int m, m1;
 142         int hash, hash1;
 143         int fd = (int)(long)user;
 144 #endif
 145
 146         switch (reason) {
 147         case LWS_CALLBACK_HTTP:
 148
 149                 for (n = 0; n < (sizeof(whitelist) / sizeof(whitelist[0]) - 1); n++)
 150                         if (in && strcmp(in, whitelist[n].urlpath) == 0)
 151                                 break;
 152
 153                 sprintf(buf, LOCAL_RESOURCE_PATH"%s", whitelist[n].urlpath);
 154
 155                 if (libwebsockets_serve_http_file(context, wsi, buf, whitelist[n].mimetype))
 156                         fprintf(stderr, "Failed to send HTTP file\n");
 157
 158                 /*
 159                  * notice that the sending of the file completes asynchronously,
 160                  * we'll get a LWS_CALLBACK_HTTP_FILE_COMPLETION callback when
 161                  * it's done
 162                  */
 163
 164                 break;
 165
 166         case LWS_CALLBACK_HTTP_FILE_COMPLETION:
 167 //              fprintf(stderr, "LWS_CALLBACK_HTTP_FILE_COMPLETION seen\n");
 168                 /* kill the connection after we sent one file */
 169                 return 1;
 170
 171         /*
 172          * callback for confirming to continue with client IP appear in
 173          * protocol 0 callback since no websocket protocol has been agreed
 174          * yet.  You can just ignore this if you won't filter on client IP
 175          * since the default uhandled callback return is 0 meaning let the
 176          * connection continue.
 177          */
 178
 179         case LWS_CALLBACK_FILTER_NETWORK_CONNECTION:
 180
 181                 libwebsockets_get_peer_addresses((int)(long)user, client_name,
 182                              sizeof(client_name), client_ip, sizeof(client_ip));
 183
 184 //              fprintf(stderr, "Received network connect from %s (%s)\n",
 185 //                                                      client_name, client_ip);
 186
 187                 /* if we returned non-zero from here, we kill the connection */
 188                 break;
 189
 190 #ifdef EXTERNAL_POLL
 191         /*
 192          * callbacks for managing the external poll() array appear in
 193          * protocol 0 callback
 194          */
 195
 196         case LWS_CALLBACK_ADD_POLL_FD:
 197                 if (count_pollfds == MAX_POLL_ELEMENTS) {
 198                         fprintf(stderr, "LWS_CALLBACK_ADD_POLL_FD: too many sockets to track\n");
 199                         return 1;
 200                 }
 201                 hash = POLL_HASH(fd);
 202                 if (pollfd_count[hash] == POLL_ENTRIES_PER_BUCKET) {
 203                         fprintf(stderr, "LWS_CALLBACK_ADD_POLL_FD: hash table overflow\n");
 204                         return 1;
 205                 }
 206
 207 //              fprintf(stderr, "Adding fd %d at pollfd_maps[%d][%d], pollfds[%d]\n", fd, hash, pollfd_count[hash], count_pollfds);
 208
 209                 pollfd_maps[hash][pollfd_count[hash]].fd = fd;
 210                 pollfd_maps[hash][pollfd_count[hash]++].index = count_pollfds;
 211
 212                 pollfds[count_pollfds].fd = (int)(long)user;
 213                 pollfds[count_pollfds].events = (int)len;
 214                 pollfds[count_pollfds++].revents = 0;
 215                 break;
 216
 217         case LWS_CALLBACK_DEL_POLL_FD:
 218                 hash = POLL_HASH(fd);
 219                 n = find_poll_map_index(hash, fd);
 220                 if (n < 0) {
 221                         fprintf(stderr, "unable to find fd %d in poll_maps\n", fd);
 222                         return 1;
 223                 }
 224                 m = pollfd_maps[hash][n].index;
 225
 226                 assert(pollfds[m].fd == fd);
 227                 assert(count_pollfds);
 228                 assert(pollfd_count[hash]);
 229
 230 //              fprintf(stderr, "Removing fd %d at pollfd_maps[%d][%d], pollfds[%d]\n", fd, hash, n, m);
 231
 232                 /*
 233                  * swap the end guy into our vacant slot...
 234                  * works ok if n is the end guy
 235                  */
 236
 237                 count_pollfds--;
 238                 if (count_pollfds) {
 239
 240                         /* end guy... */
 241                         hash1 = POLL_HASH(pollfds[count_pollfds].fd);
 242                         m1 = find_poll_map_index(hash1, pollfds[count_pollfds].fd);
 243                         /* your index has changed... */
 244                         pollfd_maps[hash1][m1].index = m;
 245
 246                         pollfds[m] = pollfds[count_pollfds];
 247                         pollfds[count_pollfds].fd = -1;
 248                 }
 249
 250                 /*
 251                  * similar trick with hashtable
 252                  * old end guy goes into vacant slot in hash table
 253                  */
 254
 255 /* some versions of gcc see a false positive here, workaround */
 256 #ifdef __GNUC__
 257 #pragma GCC diagnostic ignored "-Warray-bounds"
 258 #endif
 259                 pollfd_count[hash]--;
 260                 if (pollfd_count[hash]) {
 261                         pollfd_maps[hash][n].index = pollfd_maps[hash][pollfd_count[hash]].index;
 262                         pollfd_maps[hash][n].fd = pollfd_maps[hash][pollfd_count[hash]].fd;
 263                 }
 264 #ifdef __GNUC__
 265 #pragma GCC diagnostic pop
 266 #endif
 267                 break;
 268
 269         case LWS_CALLBACK_SET_MODE_POLL_FD:
 270                 n = find_pollfd_index(fd);
 271                 if (n < 0) {
 272                         fprintf(stderr, "unable to find fd %d\n", fd);
 273                         return 1;
 274                 }
 275                 if(pollfds[n].fd != fd) {
 276                         fprintf(stderr, "Setting fd %d, found at pollfd_index %d, actually fd %d\n", fd, n, pollfds[n].fd);
 277                         assert(0);
 278                 }
 279                 pollfds[n].events |= (int)(long)len;
 280                 break;
 281
 282         case LWS_CALLBACK_CLEAR_MODE_POLL_FD:
 283                 n = find_pollfd_index(fd);
 284                 if (n < 0) {
 285                         fprintf(stderr, "unable to find fd %d\n", fd);
 286                         return 1;
 287                 }
 288                 assert(pollfds[n].fd == fd);
 289                 pollfds[n].events &= ~(int)(long)len;
 290                 break;
 291 #endif
 292         default:
 293                 break;
 294         }
 295
 296         return 0;
 297 }
 298
 299
 300 /*
 301  * this is just an example of parsing handshake headers, you don't need this
 302  * in your code unless you will filter allowing connections by the header
 303  * content
 304  */
 305
 306 static void
 307 dump_handshake_info(struct lws_tokens *lwst)
 308 {
 309         int n;
 310         static const char *token_names[WSI_TOKEN_COUNT] = {
 311                 /*[WSI_TOKEN_GET_URI]           =*/ "GET URI",
 312                 /*[WSI_TOKEN_HOST]              =*/ "Host",
 313                 /*[WSI_TOKEN_CONNECTION]        =*/ "Connection",
 314                 /*[WSI_TOKEN_KEY1]              =*/ "key 1",
 315                 /*[WSI_TOKEN_KEY2]              =*/ "key 2",
 316                 /*[WSI_TOKEN_PROTOCOL]          =*/ "Protocol",
 317                 /*[WSI_TOKEN_UPGRADE]           =*/ "Upgrade",
 318                 /*[WSI_TOKEN_ORIGIN]            =*/ "Origin",
 319                 /*[WSI_TOKEN_DRAFT]             =*/ "Draft",
 320                 /*[WSI_TOKEN_CHALLENGE]         =*/ "Challenge",
 321
 322                 /* new for 04 */
 323                 /*[WSI_TOKEN_KEY]               =*/ "Key",
 324                 /*[WSI_TOKEN_VERSION]           =*/ "Version",
 325                 /*[WSI_TOKEN_SWORIGIN]          =*/ "Sworigin",
 326
 327                 /* new for 05 */
 328                 /*[WSI_TOKEN_EXTENSIONS]        =*/ "Extensions",
 329
 330                 /* client receives these */
 331                 /*[WSI_TOKEN_ACCEPT]            =*/ "Accept",
 332                 /*[WSI_TOKEN_NONCE]             =*/ "Nonce",
 333                 /*[WSI_TOKEN_HTTP]              =*/ "Http",
 334                 /*[WSI_TOKEN_MUXURL]    =*/ "MuxURL",
 335         };
 336
 337         for (n = 0; n < WSI_TOKEN_COUNT; n++) {
 338                 if (lwst[n].token == NULL)
 339                         continue;
 340
 341                 fprintf(stderr, "    %s = %s\n", token_names[n], lwst[n].token);
 342         }
 343 }
 344
 345 /* dumb_increment protocol */
 346
 347 /*
 348  * one of these is auto-created for each connection and a pointer to the
 349  * appropriate instance is passed to the callback in the user parameter
 350  *
 351  * for this example protocol we use it to individualize the count for each
 352  * connection.
 353  */
 354
 355 struct per_session_data__dumb_increment {
 356         int number;
 357 };
 358
 359 static int
 360 callback_dumb_increment(struct libwebsocket_context *context,
 361                         struct libwebsocket *wsi,
 362                         enum libwebsocket_callback_reasons reason,
 363                                                void *user, void *in, size_t len)
 364 {
 365         int n;
 366         unsigned char buf[LWS_SEND_BUFFER_PRE_PADDING + 512 +
 367                                                   LWS_SEND_BUFFER_POST_PADDING];
 368         unsigned char *p = &buf[LWS_SEND_BUFFER_PRE_PADDING];
 369         struct per_session_data__dumb_increment *pss = user;
 370
 371         switch (reason) {
 372
 373         case LWS_CALLBACK_ESTABLISHED:
 374                 fprintf(stderr, "callback_dumb_increment: "
 375                                                  "LWS_CALLBACK_ESTABLISHED\n");
 376                 pss->number = 0;
 377                 break;
 378
 379         /*
 380          * in this protocol, we just use the broadcast action as the chance to
 381          * send our own connection-specific data and ignore the broadcast info
 382          * that is available in the 'in' parameter
 383          */
 384
 385         case LWS_CALLBACK_BROADCAST:
 386                 n = sprintf((char *)p, "%d", pss->number++);
 387                 n = libwebsocket_write(wsi, p, n, LWS_WRITE_TEXT);
 388                 if (n < 0) {
 389                         fprintf(stderr, "ERROR %d writing to socket\n", n);
 390                         return 1;
 391                 }
 392                 if (close_testing && pss->number == 50) {
 393                         fprintf(stderr, "close tesing limit, closing\n");
 394                         libwebsocket_close_and_free_session(context, wsi,
 395                                                        LWS_CLOSE_STATUS_NORMAL);
 396                 }
 397                 break;
 398
 399         case LWS_CALLBACK_RECEIVE:
 400                 fprintf(stderr, "rx %d\n", (int)len);
 401                 if (len < 6)
 402                         break;
 403                 if (strcmp(in, "reset\n") == 0)
 404                         pss->number = 0;
 405                 break;
 406         /*
 407          * this just demonstrates how to use the protocol filter. If you won't
 408          * study and reject connections based on header content, you don't need
 409          * to handle this callback
 410          */
 411
 412         case LWS_CALLBACK_FILTER_PROTOCOL_CONNECTION:
 413                 dump_handshake_info((struct lws_tokens *)(long)user);
 414                 /* you could return non-zero here and kill the connection */
 415                 break;
 416
 417         default:
 418                 break;
 419         }
 420
 421         return 0;
 422 }
 423
 424
 425 /* lws-mirror_protocol */
 426
 427 #define MAX_MESSAGE_QUEUE 64
 428
 429 struct per_session_data__lws_mirror {
 430         struct libwebsocket *wsi;
 431         int ringbuffer_tail;
 432 };
 433
 434 struct a_message {
 435         void *payload;
 436         size_t len;
 437 };
 438
 439 static struct a_message ringbuffer[MAX_MESSAGE_QUEUE];
 440 static int ringbuffer_head;
 441
 442
 443 static int
 444 callback_lws_mirror(struct libwebsocket_context *context,
 445                         struct libwebsocket *wsi,
 446                         enum libwebsocket_callback_reasons reason,
 447                                                void *user, void *in, size_t len)
 448 {
 449         int n;
 450         struct per_session_data__lws_mirror *pss = user;
 451
 452         switch (reason) {
 453
 454         case LWS_CALLBACK_ESTABLISHED:
 455                 fprintf(stderr, "callback_lws_mirror: "
 456                                                  "LWS_CALLBACK_ESTABLISHED\n");
 457                 pss->ringbuffer_tail = ringbuffer_head;
 458                 pss->wsi = wsi;
 459                 break;
 460
 461         case LWS_CALLBACK_SERVER_WRITEABLE:
 462                 if (close_testing)
 463                         break;
 464                 if (pss->ringbuffer_tail != ringbuffer_head) {
 465
 466                         n = libwebsocket_write(wsi, (unsigned char *)
 467                                    ringbuffer[pss->ringbuffer_tail].payload +
 468                                    LWS_SEND_BUFFER_PRE_PADDING,
 469                                    ringbuffer[pss->ringbuffer_tail].len,
 470                                                                 LWS_WRITE_TEXT);
 471                         if (n < 0) {
 472                                 fprintf(stderr, "ERROR %d writing to socket\n", n);
 473                                 exit(1);
 474                         }
 475
 476                         if (pss->ringbuffer_tail == (MAX_MESSAGE_QUEUE - 1))
 477                                 pss->ringbuffer_tail = 0;
 478                         else
 479                                 pss->ringbuffer_tail++;
 480
 481                         if (((ringbuffer_head - pss->ringbuffer_tail) %
 482                                   MAX_MESSAGE_QUEUE) < (MAX_MESSAGE_QUEUE - 15))
 483                                 libwebsocket_rx_flow_control(wsi, 1);
 484
 485                         libwebsocket_callback_on_writable(context, wsi);
 486
 487                 }
 488                 break;
 489
 490         case LWS_CALLBACK_BROADCAST:
 491                 n = libwebsocket_write(wsi, in, len, LWS_WRITE_TEXT);
 492                 if (n < 0)
 493                         fprintf(stderr, "mirror write failed\n");
 494                 break;
 495
 496         case LWS_CALLBACK_RECEIVE:
 497
 498                 if (ringbuffer[ringbuffer_head].payload)
 499                         free(ringbuffer[ringbuffer_head].payload);
 500
 501                 ringbuffer[ringbuffer_head].payload =
 502                                 malloc(LWS_SEND_BUFFER_PRE_PADDING + len +
 503                                                   LWS_SEND_BUFFER_POST_PADDING);
 504                 ringbuffer[ringbuffer_head].len = len;
 505                 memcpy((char *)ringbuffer[ringbuffer_head].payload +
 506                                           LWS_SEND_BUFFER_PRE_PADDING, in, len);
 507                 if (ringbuffer_head == (MAX_MESSAGE_QUEUE - 1))
 508                         ringbuffer_head = 0;
 509                 else
 510                         ringbuffer_head++;
 511
 512                 if (((ringbuffer_head - pss->ringbuffer_tail) %
 513                                   MAX_MESSAGE_QUEUE) > (MAX_MESSAGE_QUEUE - 10))
 514                         libwebsocket_rx_flow_control(wsi, 0);
 515
 516                 libwebsocket_callback_on_writable_all_protocol(
 517                                                libwebsockets_get_protocol(wsi));
 518                 break;
 519         /*
 520          * this just demonstrates how to use the protocol filter. If you won't
 521          * study and reject connections based on header content, you don't need
 522          * to handle this callback
 523          */
 524
 525         case LWS_CALLBACK_FILTER_PROTOCOL_CONNECTION:
 526                 dump_handshake_info((struct lws_tokens *)(long)user);
 527                 /* you could return non-zero here and kill the connection */
 528                 break;
 529
 530         default:
 531                 break;
 532         }
 533
 534         return 0;
 535 }
 536
 537
 538 /* list of supported protocols and callbacks */
 539
 540 static struct libwebsocket_protocols protocols[] = {
 541         /* first protocol must always be HTTP handler */
 542
 543         {
 544                 "http-only",            /* name */
 545                 callback_http,          /* callback */
 546                 0                       /* per_session_data_size */
 547         },
 548         {
 549                 "dumb-increment-protocol",
 550                 callback_dumb_increment,
 551                 sizeof(struct per_session_data__dumb_increment),
 552         },
 553         {
 554                 "lws-mirror-protocol",
 555                 callback_lws_mirror,
 556                 sizeof(struct per_session_data__lws_mirror)
 557         },
 558         {
 559                 NULL, NULL, 0           /* End of list */
 560         }
 561 };
 562
 563 static struct option options[] = {
 564         { "help",       no_argument,            NULL, 'h' },
 565         { "debug",      required_argument,      NULL, 'd' },
 566         { "port",       required_argument,      NULL, 'p' },
 567         { "ssl",        no_argument,            NULL, 's' },
 568         { "killmask",   no_argument,            NULL, 'k' },
 569         { "interface",  required_argument,      NULL, 'i' },
 570         { "closetest",  no_argument,            NULL, 'c' },
 571         { NULL, 0, 0, 0 }
 572 };
 573
 574 int main(int argc, char **argv)
 575 {
 576         int n = 0;
 577         const char *cert_path =
 578                             LOCAL_RESOURCE_PATH"/libwebsockets-test-server.pem";
 579         const char *key_path =
 580                         LOCAL_RESOURCE_PATH"/libwebsockets-test-server.key.pem";
 581         unsigned char buf[LWS_SEND_BUFFER_PRE_PADDING + 1024 +
 582                                                   LWS_SEND_BUFFER_POST_PADDING];
 583         int port = 7681;
 584         int use_ssl = 0;
 585         struct libwebsocket_context *context;
 586         int opts = 0;
 587         char interface_name[128] = "";
 588         const char *interface = NULL;
 589 #ifdef LWS_NO_FORK
 590         unsigned int oldus = 0;
 591 #endif
 592
 593         fprintf(stderr, "libwebsockets test server\n"
 594                         "(C) Copyright 2010-2013 Andy Green <andy@warmcat.com> "
 595                                                     "licensed under LGPL2.1\n");
 596
 597         while (n >= 0) {
 598                 n = getopt_long(argc, argv, "ci:khsp:d:", options, NULL);
 599                 if (n < 0)
 600                         continue;
 601                 switch (n) {
 602                 case 'd':
 603                         lws_set_log_level(atoi(optarg), NULL);
 604                         break;
 605                 case 's':
 606                         use_ssl = 1;
 607                         break;
 608                 case 'k':
 609                         opts = LWS_SERVER_OPTION_DEFEAT_CLIENT_MASK;
 610                         break;
 611                 case 'p':
 612                         port = atoi(optarg);
 613                         break;
 614                 case 'i':
 615                         strncpy(interface_name, optarg, sizeof interface_name);
 616                         interface_name[(sizeof interface_name) - 1] = '\0';
 617                         interface = interface_name;
 618                         break;
 619                 case 'c':
 620                         close_testing = 1;
 621                         fprintf(stderr, " Close testing mode -- closes on "
 622                                            "client after 50 dumb increments"
 623                                            "and suppresses lws_mirror spam\n");
 624                         break;
 625                 case 'h':
 626                         fprintf(stderr, "Usage: test-server "
 627                                         "[--port=<p>] [--ssl] "
 628                                         "[-d <log bitfield>]\n");
 629                         exit(1);
 630                 }
 631         }
 632
 633         if (!use_ssl)
 634                 cert_path = key_path = NULL;
 635
 636         context = libwebsocket_create_context(port, interface, protocols,
 637                                 libwebsocket_internal_extensions,
 638                                 cert_path, key_path, NULL, -1, -1, opts, NULL);
 639         if (context == NULL) {
 640                 fprintf(stderr, "libwebsocket init failed\n");
 641                 return -1;
 642         }
 643
 644         buf[LWS_SEND_BUFFER_PRE_PADDING] = 'x';
 645
 646 #ifdef LWS_NO_FORK
 647
 648         /*
 649          * This example shows how to work with no forked service loop
 650          */
 651
 652         fprintf(stderr, " Using no-fork service loop\n");
 653
 654         n = 0;
 655         while (n >= 0) {
 656                 struct timeval tv;
 657
 658                 gettimeofday(&tv, NULL);
 659
 660                 /*
 661                  * This broadcasts to all dumb-increment-protocol connections
 662                  * at 20Hz.
 663                  *
 664                  * We're just sending a character 'x', in these examples the
 665                  * callbacks send their own per-connection content.
 666                  *
 667                  * You have to send something with nonzero length to get the
 668                  * callback actions delivered.
 669                  *
 670                  * We take care of pre-and-post padding allocation.
 671                  */
 672
 673                 if (((unsigned int)tv.tv_usec - oldus) > 50000) {
 674                         libwebsockets_broadcast(
 675                                         &protocols[PROTOCOL_DUMB_INCREMENT],
 676                                         &buf[LWS_SEND_BUFFER_PRE_PADDING], 1);
 677                         oldus = tv.tv_usec;
 678                 }
 679
 680                 /*
 681                  * This example server does not fork or create a thread for
 682                  * websocket service, it all runs in this single loop.  So,
 683                  * we have to give the websockets an opportunity to service
 684                  * "manually".
 685                  *
 686                  * If no socket is needing service, the call below returns
 687                  * immediately and quickly.  Negative return means we are
 688                  * in process of closing
 689                  */
 690 #ifdef EXTERNAL_POLL
 691
 692                 /*
 693                  * this represents an existing server's single poll action
 694                  * which also includes libwebsocket sockets
 695                  */
 696
 697                 n = poll(pollfds, count_pollfds, 50);
 698                 if (n < 0)
 699                         continue;
 700
 701
 702                 if (n)
 703                         for (n = 0; n < count_pollfds; n++)
 704                                 if (pollfds[n].revents)
 705                                         /*
 706                                         * returns immediately if the fd does not
 707                                         * match anything under libwebsockets
 708                                         * control
 709                                         */
 710                                         if (libwebsocket_service_fd(context,
 711                                                                   &pollfds[n]) < 0)
 712                                                 goto done;
 713 #else
 714                 n = libwebsocket_service(context, 50);
 715 #endif
 716         }
 717
 718 #else /* !LWS_NO_FORK */
 719
 720         /*
 721          * This example shows how to work with the forked websocket service loop
 722          */
 723
 724         fprintf(stderr, " Using forked service loop\n");
 725
 726         /*
 727          * This forks the websocket service action into a subprocess so we
 728          * don't have to take care about it.
 729          */
 730
 731         n = libwebsockets_fork_service_loop(context);
 732         if (n < 0) {
 733                 fprintf(stderr, "Unable to fork service loop %d\n", n);
 734                 return 1;
 735         }
 736
 737         while (1) {
 738
 739                 usleep(50000);
 740
 741                 /*
 742                  * This broadcasts to all dumb-increment-protocol connections
 743                  * at 20Hz.
 744                  *
 745                  * We're just sending a character 'x', in these examples the
 746                  * callbacks send their own per-connection content.
 747                  *
 748                  * You have to send something with nonzero length to get the
 749                  * callback actions delivered.
 750                  *
 751                  * We take care of pre-and-post padding allocation.
 752                  */
 753
 754                 libwebsockets_broadcast(&protocols[PROTOCOL_DUMB_INCREMENT],
 755                                         &buf[LWS_SEND_BUFFER_PRE_PADDING], 1);
 756         }
 757
 758 #endif
 759 #ifdef EXTERNAL_POLL
 760 done:
 761 #endif
 762
 763         libwebsocket_context_destroy(context);
 764
 765         return 0;
 766 }