lib/libwebsockets.c

   1 /*
   2  * libwebsockets - small server side websockets and web server implementation
   3  *
   4  * Copyright (C) 2010 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 LWS_OPENSSL_SUPPORT
  25 SSL_CTX *ssl_ctx;
  26 int use_ssl;
  27 #endif
  28
  29 void
  30 libwebsocket_close_and_free_session(struct libwebsocket *wsi)
  31 {
  32         int n;
  33
  34         if ((unsigned long)wsi < LWS_MAX_PROTOCOLS)
  35                 return;
  36
  37         n = wsi->state;
  38
  39         wsi->state = WSI_STATE_DEAD_SOCKET;
  40
  41         if (wsi->protocol->callback && n == WSI_STATE_ESTABLISHED)
  42                 wsi->protocol->callback(wsi, LWS_CALLBACK_CLOSED,
  43                                                       wsi->user_space, NULL, 0);
  44
  45         for (n = 0; n < WSI_TOKEN_COUNT; n++)
  46                 if (wsi->utf8_token[n].token)
  47                         free(wsi->utf8_token[n].token);
  48
  49 /*      fprintf(stderr, "closing fd=%d\n", wsi->sock); */
  50
  51 #ifdef LWS_OPENSSL_SUPPORT
  52         if (use_ssl) {
  53                 n = SSL_get_fd(wsi->ssl);
  54                 SSL_shutdown(wsi->ssl);
  55                 close(n);
  56                 SSL_free(wsi->ssl);
  57         } else {
  58 #endif
  59                 shutdown(wsi->sock, SHUT_RDWR);
  60                 close(wsi->sock);
  61 #ifdef LWS_OPENSSL_SUPPORT
  62         }
  63 #endif
  64         if (wsi->user_space)
  65                 free(wsi->user_space);
  66
  67         free(wsi);
  68 }
  69
  70 static int
  71 libwebsocket_poll_connections(struct libwebsocket_context *this)
  72 {
  73         unsigned char buf[LWS_SEND_BUFFER_PRE_PADDING + MAX_BROADCAST_PAYLOAD +
  74                                                   LWS_SEND_BUFFER_POST_PADDING];
  75         int client = this->count_protocols + 1;
  76         struct libwebsocket *wsi;
  77         int n;
  78         size_t len;
  79
  80         /* check for activity on client sockets */
  81
  82         for (; client < this->fds_count; client++) {
  83
  84                 /* handle session socket closed */
  85
  86                 if (this->fds[client].revents & (POLLERR | POLLHUP)) {
  87
  88                         debug("Session Socket %d %p (fd=%d) dead\n",
  89                                   client, this->wsi[client], this->fds[client]);
  90
  91                         libwebsocket_close_and_free_session(this->wsi[client]);
  92                         goto nuke_this;
  93                 }
  94
  95                 /* any incoming data ready? */
  96
  97                 if (!(this->fds[client].revents & POLLIN))
  98                         continue;
  99
 100                 /* broadcast? */
 101
 102                 if ((unsigned long)this->wsi[client] < LWS_MAX_PROTOCOLS) {
 103
 104                         /* get the issued broadcast payload from the socket */
 105
 106                         len = read(this->fds[client].fd,
 107                                    buf + LWS_SEND_BUFFER_PRE_PADDING,
 108                                    MAX_BROADCAST_PAYLOAD);
 109
 110                         if (len < 0) {
 111                                 fprintf(stderr,
 112                                            "Error reading broadcast payload\n");
 113                                 continue;
 114                         }
 115
 116                         /* broadcast it to all guys with this protocol index */
 117
 118                         for (n = this->count_protocols + 1;
 119                                                      n < this->fds_count; n++) {
 120
 121                                 wsi = this->wsi[n];
 122
 123                                 if ((unsigned long)wsi < LWS_MAX_PROTOCOLS)
 124                                         continue;
 125
 126                                 /*
 127                                  * never broadcast to non-established
 128                                  * connection
 129                                  */
 130
 131                                 if (wsi->state != WSI_STATE_ESTABLISHED)
 132                                         continue;
 133
 134                                 /*
 135                                  * only broadcast to connections using
 136                                  * the requested protocol
 137                                  */
 138
 139                                 if (wsi->protocol->protocol_index !=
 140                                           (int)(unsigned long)this->wsi[client])
 141                                         continue;
 142
 143                                 /* broadcast it to this connection */
 144
 145                                 wsi->protocol->callback(wsi,
 146                                         LWS_CALLBACK_BROADCAST,
 147                                         wsi->user_space,
 148                                         buf + LWS_SEND_BUFFER_PRE_PADDING, len);
 149                         }
 150
 151                         continue;
 152                 }
 153
 154 #ifdef LWS_OPENSSL_SUPPORT
 155                 if (this->use_ssl)
 156                         n = SSL_read(this->wsi[client]->ssl, buf, sizeof buf);
 157                 else
 158 #endif
 159                         n = recv(this->fds[client].fd, buf, sizeof buf, 0);
 160
 161                 if (n < 0) {
 162                         fprintf(stderr, "Socket read returned %d\n", n);
 163                         continue;
 164                 }
 165                 if (!n) {
 166                         libwebsocket_close_and_free_session(this->wsi[client]);
 167                         goto nuke_this;
 168                 }
 169
 170                 /* service incoming data */
 171
 172                 if (libwebsocket_read(this->wsi[client], buf, n) >= 0)
 173                         continue;
 174
 175                 /*
 176                  * it closed and nuked wsi[client], so remove the
 177                  * socket handle and wsi from our service list
 178                  */
 179 nuke_this:
 180
 181                 debug("nuking wsi %p, fsd_count = %d\n",
 182                                         this->wsi[client], this->fds_count - 1);
 183
 184                 this->fds_count--;
 185                 for (n = client; n < this->fds_count; n++) {
 186                         this->fds[n] = this->fds[n + 1];
 187                         this->wsi[n] = this->wsi[n + 1];
 188                 }
 189                 break;
 190         }
 191
 192         return 0;
 193 }
 194
 195
 196 int
 197 libwebsocket_service(struct libwebsocket_context *this, int timeout_ms)
 198 {
 199         int n;
 200         int client;
 201         unsigned int clilen;
 202         struct sockaddr_in cli_addr;
 203         int fd;
 204
 205         /* stay dead once we are dead */
 206
 207         if (this == NULL)
 208                 return 1;
 209
 210         n = poll(this->fds, this->fds_count, timeout_ms);
 211
 212         if (n < 0 || this->fds[0].revents & (POLLERR | POLLHUP)) {
 213                 fprintf(stderr, "Listen Socket dead\n");
 214                 goto fatal;
 215         }
 216         if (n == 0) /* poll timeout */
 217                 return 0;
 218
 219         /* handle accept on listening socket? */
 220
 221         for (client = 0; client < this->count_protocols + 1; client++) {
 222
 223                 if (!this->fds[client].revents & POLLIN)
 224                         continue;
 225
 226                 /* listen socket got an unencrypted connection... */
 227
 228                 clilen = sizeof(cli_addr);
 229                 fd  = accept(this->fds[client].fd,
 230                              (struct sockaddr *)&cli_addr, &clilen);
 231                 if (fd < 0) {
 232                         fprintf(stderr, "ERROR on accept");
 233                         continue;
 234                 }
 235
 236                 if (this->fds_count >= MAX_CLIENTS) {
 237                         fprintf(stderr, "too busy");
 238                         close(fd);
 239                         continue;
 240                 }
 241
 242                 if (client) {
 243                         /*
 244                          * accepting a connection to broadcast socket
 245                          * set wsi to be protocol index not pointer
 246                          */
 247
 248                         this->wsi[this->fds_count] =
 249                               (struct libwebsocket *)(long)(client - 1);
 250
 251                         goto fill_in_fds;
 252                 }
 253
 254                 /* accepting connection to main listener */
 255
 256                 this->wsi[this->fds_count] =
 257                                     malloc(sizeof(struct libwebsocket));
 258                 if (!this->wsi[this->fds_count]) {
 259                         fprintf(stderr, "Out of memory for new connection\n");
 260                         continue;
 261                 }
 262
 263 #ifdef LWS_OPENSSL_SUPPORT
 264                 if (this->use_ssl) {
 265
 266                         this->wsi[this->fds_count]->ssl = SSL_new(ssl_ctx);
 267                         if (this->wsi[this->fds_count]->ssl == NULL) {
 268                                 fprintf(stderr, "SSL_new failed: %s\n",
 269                                     ERR_error_string(SSL_get_error(
 270                                     this->wsi[this->fds_count]->ssl, 0),
 271                                                                  NULL));
 272                                 free(this->wsi[this->fds_count]);
 273                                 continue;
 274                         }
 275
 276                         SSL_set_fd(this->wsi[this->fds_count]->ssl, fd);
 277
 278                         n = SSL_accept(this->wsi[this->fds_count]->ssl);
 279                         if (n != 1) {
 280                                 /*
 281                                  * browsers seem to probe with various
 282                                  * ssl params which fail then retry
 283                                  * and succeed
 284                                  */
 285                                 debug("SSL_accept failed skt %u: %s\n",
 286                                       fd,
 287                                       ERR_error_string(SSL_get_error(
 288                                       this->wsi[this->fds_count]->ssl,
 289                                                              n), NULL));
 290                                 SSL_free(
 291                                        this->wsi[this->fds_count]->ssl);
 292                                 free(this->wsi[this->fds_count]);
 293                                 continue;
 294                         }
 295                         debug("accepted new SSL conn  "
 296                               "port %u on fd=%d SSL ver %s\n",
 297                                 ntohs(cli_addr.sin_port), fd,
 298                                   SSL_get_version(this->wsi[
 299                                                 this->fds_count]->ssl));
 300
 301                 } else
 302 #endif
 303                         debug("accepted new conn  port %u on fd=%d\n",
 304                                           ntohs(cli_addr.sin_port), fd);
 305
 306                 /* intialize the instance struct */
 307
 308                 this->wsi[this->fds_count]->sock = fd;
 309                 this->wsi[this->fds_count]->state = WSI_STATE_HTTP;
 310                 this->wsi[this->fds_count]->name_buffer_pos = 0;
 311
 312                 for (n = 0; n < WSI_TOKEN_COUNT; n++) {
 313                         this->wsi[this->fds_count]->
 314                                              utf8_token[n].token = NULL;
 315                         this->wsi[this->fds_count]->
 316                                             utf8_token[n].token_len = 0;
 317                 }
 318
 319                 /*
 320                  * these can only be set once the protocol is known
 321                  * we set an unestablished connection's protocol pointer
 322                  * to the start of the supported list, so it can look
 323                  * for matching ones during the handshake
 324                  */
 325                 this->wsi[this->fds_count]->protocol = this->protocols;
 326                 this->wsi[this->fds_count]->user_space = NULL;
 327
 328                 /*
 329                  * Default protocol is 76 / 00
 330                  * After 76, there's a header specified to inform which
 331                  * draft the client wants, when that's seen we modify
 332                  * the individual connection's spec revision accordingly
 333                  */
 334                 this->wsi[this->fds_count]->ietf_spec_revision = 0;
 335
 336 fill_in_fds:
 337
 338                 /*
 339                  * make sure NO events are seen yet on this new socket
 340                  * (otherwise we inherit old fds[client].revents from
 341                  * previous socket there and die mysteriously! )
 342                  */
 343                 this->fds[this->fds_count].revents = 0;
 344
 345                 this->fds[this->fds_count].events = POLLIN;
 346                 this->fds[this->fds_count++].fd = fd;
 347
 348         }
 349
 350         /* service anything incoming on websocket connection */
 351
 352         libwebsocket_poll_connections(this);
 353
 354         /* this round is done */
 355
 356         return 0;
 357
 358 fatal:
 359
 360         /* close listening skt and per-protocol broadcast sockets */
 361         for (client = 0; client < this->fds_count; client++)
 362                 close(this->fds[0].fd);
 363
 364 #ifdef LWS_OPENSSL_SUPPORT
 365         SSL_CTX_free(ssl_ctx);
 366 #endif
 367         kill(0, SIGTERM);
 368
 369         if (this)
 370                 free(this);
 371
 372         this = NULL;
 373
 374         /* inform caller we are dead */
 375
 376         return 1;
 377 }
 378
 379
 380 /**
 381  * libwebsocket_create_server() - Create the listening websockets server
 382  * @port:       Port to listen on
 383  * @protocols:  Array of structures listing supported protocols and a protocol-
 384  *              specific callback for each one.  The list is ended with an
 385  *              entry that has a NULL callback pointer.
 386  *              It's not const because we write the owning_server member
 387  * @ssl_cert_filepath:  If libwebsockets was compiled to use ssl, and you want
 388  *                      to listen using SSL, set to the filepath to fetch the
 389  *                      server cert from, otherwise NULL for unencrypted
 390  * @ssl_private_key_filepath: filepath to private key if wanting SSL mode,
 391  *                      else ignored
 392  * @gid:        group id to change to after setting listen socket, or -1.
 393  * @uid:        user id to change to after setting listen socket, or -1.
 394  *
 395  *      This function creates the listening socket and takes care
 396  *      of all initialization in one step.
 397  *
 398  *      After initialization, it returns a struct libwebsocket_context * that
 399  *      represents this server.  After calling, user code needs to take care
 400  *      of calling libwebsocket_service() with the context pointer to get the
 401  *      server's sockets serviced.  This can be done in the same process context
 402  *      or a forked process, or another thread,
 403  *
 404  *      The protocol callback functions are called for a handful of events
 405  *      including http requests coming in, websocket connections becoming
 406  *      established, and data arriving; it's also called periodically to allow
 407  *      async transmission.
 408  *
 409  *      HTTP requests are sent always to the FIRST protocol in @protocol, since
 410  *      at that time websocket protocol has not been negotiated.  Other
 411  *      protocols after the first one never see any HTTP callack activity.
 412  *
 413  *      The server created is a simple http server by default; part of the
 414  *      websocket standard is upgrading this http connection to a websocket one.
 415  *
 416  *      This allows the same server to provide files like scripts and favicon /
 417  *      images or whatever over http and dynamic data over websockets all in
 418  *      one place; they're all handled in the user callback.
 419  */
 420
 421 struct libwebsocket_context *
 422 libwebsocket_create_server(int port,
 423                                struct libwebsocket_protocols *protocols,
 424                                const char *ssl_cert_filepath,
 425                                const char *ssl_private_key_filepath,
 426                                int gid, int uid)
 427 {
 428         int n;
 429         int sockfd;
 430         int fd;
 431         struct sockaddr_in serv_addr, cli_addr;
 432         int opt = 1;
 433         struct libwebsocket_context *this = NULL;
 434         unsigned int slen;
 435
 436 #ifdef LWS_OPENSSL_SUPPORT
 437         SSL_METHOD *method;
 438         char ssl_err_buf[512];
 439
 440         use_ssl = ssl_cert_filepath != NULL && ssl_private_key_filepath != NULL;
 441         if (use_ssl)
 442                 fprintf(stderr, " Compiled with SSL support, using it\n");
 443         else
 444                 fprintf(stderr, " Compiled with SSL support, not using it\n");
 445
 446 #else
 447         if (ssl_cert_filepath != NULL && ssl_private_key_filepath != NULL) {
 448                 fprintf(stderr, " Not compiled for OpenSSl support!\n");
 449                 return NULL;
 450         }
 451         fprintf(stderr, " Compiled without SSL support, serving unencrypted\n");
 452 #endif
 453
 454 #ifdef LWS_OPENSSL_SUPPORT
 455         if (use_ssl) {
 456                 SSL_library_init();
 457
 458                 OpenSSL_add_all_algorithms();
 459                 SSL_load_error_strings();
 460
 461                 /*
 462                  * Firefox insists on SSLv23 not SSLv3
 463                  * Konq disables SSLv2 by default now, SSLv23 works
 464                  */
 465
 466                 method = (SSL_METHOD *)SSLv23_server_method();
 467                 if (!method) {
 468                         fprintf(stderr, "problem creating ssl method: %s\n",
 469                                 ERR_error_string(ERR_get_error(), ssl_err_buf));
 470                         return NULL;
 471                 }
 472                 ssl_ctx = SSL_CTX_new(method);  /* create context */
 473                 if (!ssl_ctx) {
 474                         printf("problem creating ssl context: %s\n",
 475                                 ERR_error_string(ERR_get_error(), ssl_err_buf));
 476                         return NULL;
 477                 }
 478                 /* set the local certificate from CertFile */
 479                 n = SSL_CTX_use_certificate_file(ssl_ctx,
 480                                         ssl_cert_filepath, SSL_FILETYPE_PEM);
 481                 if (n != 1) {
 482                         fprintf(stderr, "problem getting cert '%s': %s\n",
 483                                 ssl_cert_filepath,
 484                                 ERR_error_string(ERR_get_error(), ssl_err_buf));
 485                         return NULL;
 486                 }
 487                 /* set the private key from KeyFile */
 488                 if (SSL_CTX_use_PrivateKey_file(ssl_ctx,
 489                                                 ssl_private_key_filepath,
 490                                                 SSL_FILETYPE_PEM) != 1) {
 491                         fprintf(stderr, "ssl problem getting key '%s': %s\n",
 492                                                 ssl_private_key_filepath,
 493                                 ERR_error_string(ERR_get_error(), ssl_err_buf));
 494                         return NULL;
 495                 }
 496                 /* verify private key */
 497                 if (!SSL_CTX_check_private_key(ssl_ctx)) {
 498                         fprintf(stderr, "Private SSL key doesn't match cert\n");
 499                         return NULL;
 500                 }
 501
 502                 /* SSL is happy and has a cert it's content with */
 503         }
 504 #endif
 505
 506         /* selftest */
 507
 508         if (lws_b64_selftest())
 509                 return NULL;
 510
 511
 512         this = malloc(sizeof(struct libwebsocket_context));
 513
 514         this->protocols = protocols;
 515
 516         /* set up our external listening socket we serve on */
 517
 518         sockfd = socket(AF_INET, SOCK_STREAM, 0);
 519         if (sockfd < 0) {
 520                 fprintf(stderr, "ERROR opening socket");
 521                 return NULL;
 522         }
 523
 524         /* allow us to restart even if old sockets in TIME_WAIT */
 525         setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt));
 526
 527         bzero((char *) &serv_addr, sizeof(serv_addr));
 528         serv_addr.sin_family = AF_INET;
 529         serv_addr.sin_addr.s_addr = INADDR_ANY;
 530         serv_addr.sin_port = htons(port);
 531
 532         n = bind(sockfd, (struct sockaddr *) &serv_addr, sizeof(serv_addr));
 533         if (n < 0) {
 534                 fprintf(stderr, "ERROR on binding to port %d (%d %d)\n",
 535                                                                 port, n, errno);
 536                 return NULL;
 537         }
 538
 539         /* drop any root privs for this process */
 540
 541         if (gid != -1)
 542                 if (setgid(gid))
 543                         fprintf(stderr, "setgid: %s\n", strerror(errno));
 544         if (uid != -1)
 545                 if (setuid(uid))
 546                         fprintf(stderr, "setuid: %s\n", strerror(errno));
 547
 548         /*
 549          * prepare the poll() fd array... it's like this
 550          *
 551          * [0] = external listening socket
 552          * [1 .. this->count_protocols] = per-protocol broadcast sockets
 553          * [this->count_protocols + 1 ... this->fds_count-1] = connection skts
 554          */
 555
 556         this->fds_count = 1;
 557         this->fds[0].fd = sockfd;
 558         this->fds[0].events = POLLIN;
 559         this->count_protocols = 0;
 560 #ifdef LWS_OPENSSL_SUPPORT
 561         this->use_ssl = use_ssl;
 562 #endif
 563
 564         listen(sockfd, 5);
 565         fprintf(stderr, " Listening on port %d\n", port);
 566
 567         /* set up our internal broadcast trigger sockets per-protocol */
 568
 569         for (; protocols[this->count_protocols].callback;
 570                                                       this->count_protocols++) {
 571                 protocols[this->count_protocols].owning_server = this;
 572                 protocols[this->count_protocols].protocol_index =
 573                                                           this->count_protocols;
 574
 575                 fd = socket(AF_INET, SOCK_STREAM, 0);
 576                 if (fd < 0) {
 577                         fprintf(stderr, "ERROR opening socket");
 578                         return NULL;
 579                 }
 580
 581                 /* allow us to restart even if old sockets in TIME_WAIT */
 582                 setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt));
 583
 584                 bzero((char *) &serv_addr, sizeof(serv_addr));
 585                 serv_addr.sin_family = AF_INET;
 586                 serv_addr.sin_addr.s_addr = inet_addr("127.0.0.1");
 587                 serv_addr.sin_port = 0; /* pick the port for us */
 588
 589                 n = bind(fd, (struct sockaddr *) &serv_addr, sizeof(serv_addr));
 590                 if (n < 0) {
 591                         fprintf(stderr, "ERROR on binding to port %d (%d %d)\n",
 592                                                                 port, n, errno);
 593                         return NULL;
 594                 }
 595
 596                 slen = sizeof cli_addr;
 597                 n = getsockname(fd, (struct sockaddr *)&cli_addr, &slen);
 598                 if (n < 0) {
 599                         fprintf(stderr, "getsockname failed\n");
 600                         return NULL;
 601                 }
 602                 protocols[this->count_protocols].broadcast_socket_port =
 603                                                        ntohs(cli_addr.sin_port);
 604                 listen(fd, 5);
 605
 606                 debug("  Protocol %s broadcast socket %d\n",
 607                                 protocols[this->count_protocols].name,
 608                                                       ntohs(cli_addr.sin_port));
 609
 610                 this->fds[this->fds_count].fd = fd;
 611                 this->fds[this->fds_count].events = POLLIN;
 612                 /* wsi only exists for connections, not broadcast listener */
 613                 this->wsi[this->fds_count] = NULL;
 614                 this->fds_count++;
 615         }
 616
 617         return this;
 618 }
 619
 620 /**
 621  * libwebsockets_fork_service_loop() - Optional helper function forks off
 622  *                                a process for the websocket server loop.
 623  *                              You don't have to use this but if not, you
 624  *                              have to make sure you are calling
 625  *                              libwebsocket_service periodically to service
 626  *                              the websocket traffic
 627  * @this:       server context returned by creation function
 628  */
 629
 630 int
 631 libwebsockets_fork_service_loop(struct libwebsocket_context *this)
 632 {
 633         int client;
 634         int fd;
 635         struct sockaddr_in cli_addr;
 636         int n;
 637
 638         if (fork())
 639                 return 0;
 640
 641         for (client = 1; client < this->count_protocols + 1; client++) {
 642                 fd = socket(AF_INET, SOCK_STREAM, 0);
 643                 if (fd < 0) {
 644                         fprintf(stderr, "Unable to create socket\n");
 645                         return -1;
 646                 }
 647                 cli_addr.sin_family = AF_INET;
 648                 cli_addr.sin_port = htons(
 649                            this->protocols[client - 1].broadcast_socket_port);
 650                 cli_addr.sin_addr.s_addr = inet_addr("127.0.0.1");
 651                 n = connect(fd, (struct sockaddr *)&cli_addr,
 652                                                        sizeof cli_addr);
 653                 if (n < 0) {
 654                         fprintf(stderr, "Unable to connect to "
 655                                         "broadcast socket %d, %s\n",
 656                                         client, strerror(errno));
 657                         return -1;
 658                 }
 659
 660                 this->protocols[client - 1].broadcast_socket_user_fd = fd;
 661         }
 662
 663         /* we want a SIGHUP when our parent goes down */
 664         prctl(PR_SET_PDEATHSIG, SIGHUP);
 665
 666         /* in this forked process, sit and service websocket connections */
 667
 668         while (1)
 669                 if (libwebsocket_service(this, 1000))
 670                         return -1;
 671
 672         return 0;
 673 }
 674
 675 /**
 676  * libwebsockets_get_protocol() - Returns a protocol pointer from a websocket
 677  *                                connection.
 678  * @wsi:        pointer to struct websocket you want to know the protocol of
 679  *
 680  *
 681  *      This is useful to get the protocol to broadcast back to from inside
 682  * the callback.
 683  */
 684
 685 const struct libwebsocket_protocols *
 686 libwebsockets_get_protocol(struct libwebsocket *wsi)
 687 {
 688         return wsi->protocol;
 689 }
 690
 691 /**
 692  * libwebsockets_broadcast() - Sends a buffer to the callback for all active
 693  *                                connections of the given protocol.
 694  * @protocol:   pointer to the protocol you will broadcast to all members of
 695  * @buf:  buffer containing the data to be broadcase.  NOTE: this has to be
 696  *              allocated with LWS_SEND_BUFFER_PRE_PADDING valid bytes before
 697  *              the pointer and LWS_SEND_BUFFER_POST_PADDING afterwards in the
 698  *              case you are calling this function from callback context.
 699  * @len:        length of payload data in buf, starting from buf.
 700  *
 701  *      This function allows bulk sending of a packet to every connection using
 702  * the given protocol.  It does not send the data directly; instead it calls
 703  * the callback with a reason type of LWS_CALLBACK_BROADCAST.  If the callback
 704  * wants to actually send the data for that connection, the callback itself
 705  * should call libwebsocket_write().
 706  *
 707  * libwebsockets_broadcast() can be called from another fork context without
 708  * having to take any care about data visibility between the processes, it'll
 709  * "just work".
 710  */
 711
 712
 713 int
 714 libwebsockets_broadcast(const struct libwebsocket_protocols *protocol,
 715                                                  unsigned char *buf, size_t len)
 716 {
 717         struct libwebsocket_context *this = protocol->owning_server;
 718         int n;
 719
 720         if (!protocol->broadcast_socket_user_fd) {
 721                 /*
 722                  * We are either running unforked / flat, or we are being
 723                  * called from poll thread context
 724                  * eg, from a callback.  In that case don't use sockets for
 725                  * broadcast IPC (since we can't open a socket connection to
 726                  * a socket listening on our own thread) but directly do the
 727                  * send action.
 728                  *
 729                  * Locking is not needed because we are by definition being
 730                  * called in the poll thread context and are serialized.
 731                  */
 732
 733                 for (n = this->count_protocols + 1; n < this->fds_count; n++) {
 734
 735                         if ((unsigned long)this->wsi[n] < LWS_MAX_PROTOCOLS)
 736                                 continue;
 737
 738                         /* never broadcast to non-established connection */
 739
 740                         if (this->wsi[n]->state != WSI_STATE_ESTABLISHED)
 741                                 continue;
 742
 743                         /* only broadcast to guys using requested protocol */
 744
 745                         if (this->wsi[n]->protocol != protocol)
 746                                 continue;
 747
 748                         this->wsi[n]->protocol->callback(this->wsi[n],
 749                                          LWS_CALLBACK_BROADCAST,
 750                                          this->wsi[n]->user_space,
 751                                          buf, len);
 752                 }
 753
 754                 return 0;
 755         }
 756
 757         /*
 758          * We're being called from a different process context than the server
 759          * loop.  Instead of broadcasting directly, we send our
 760          * payload on a socket to do the IPC; the server process will serialize
 761          * the broadcast action in its main poll() loop.
 762          *
 763          * There's one broadcast socket listening for each protocol supported
 764          * set up when the websocket server initializes
 765          */
 766
 767         n = send(protocol->broadcast_socket_user_fd, buf, len, 0);
 768
 769         return n;
 770 }