lib/service.c

   1 /*
   2  * libwebsockets - small server side websockets and web server implementation
   3  *
   4  * Copyright (C) 2010-2014 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 int
  25 lws_handle_POLLOUT_event(struct libwebsocket_context *context,
  26                    struct libwebsocket *wsi, struct libwebsocket_pollfd *pollfd)
  27 {
  28         int n;
  29         struct lws_tokens eff_buf;
  30         int ret;
  31         int m;
  32         int handled = 0;
  33
  34         /* pending truncated sends have uber priority */
  35
  36         if (wsi->truncated_send_len) {
  37                 if (lws_issue_raw(wsi, wsi->truncated_send_malloc +
  38                                 wsi->truncated_send_offset,
  39                                                 wsi->truncated_send_len) < 0) {
  40                         lwsl_info("lws_handle_POLLOUT_event signalling to close\n");
  41                         return -1;
  42                 }
  43                 /* leave POLLOUT active either way */
  44                 return 0;
  45         } else
  46                 if (wsi->state == WSI_STATE_FLUSHING_STORED_SEND_BEFORE_CLOSE) {
  47                         lwsl_info("***** %x signalling to close in POLLOUT handler\n", wsi);
  48                         return -1; /* retry closing now */
  49                 }
  50
  51
  52         m = lws_ext_callback_for_each_active(wsi, LWS_EXT_CALLBACK_IS_WRITEABLE,
  53                                                                        NULL, 0);
  54         if (handled == 1)
  55                 goto notify_action;
  56 #ifndef LWS_NO_EXTENSIONS
  57         if (!wsi->extension_data_pending || handled == 2)
  58                 goto user_service;
  59 #endif
  60         /*
  61          * check in on the active extensions, see if they
  62          * had pending stuff to spill... they need to get the
  63          * first look-in otherwise sequence will be disordered
  64          *
  65          * NULL, zero-length eff_buf means just spill pending
  66          */
  67
  68         ret = 1;
  69         while (ret == 1) {
  70
  71                 /* default to nobody has more to spill */
  72
  73                 ret = 0;
  74                 eff_buf.token = NULL;
  75                 eff_buf.token_len = 0;
  76
  77                 /* give every extension a chance to spill */
  78
  79                 m = lws_ext_callback_for_each_active(wsi,
  80                                         LWS_EXT_CALLBACK_PACKET_TX_PRESEND,
  81                                                                    &eff_buf, 0);
  82                 if (m < 0) {
  83                         lwsl_err("ext reports fatal error\n");
  84                         return -1;
  85                 }
  86                 if (m)
  87                         /*
  88                          * at least one extension told us he has more
  89                          * to spill, so we will go around again after
  90                          */
  91                         ret = 1;
  92
  93                 /* assuming they gave us something to send, send it */
  94
  95                 if (eff_buf.token_len) {
  96                         n = lws_issue_raw(wsi, (unsigned char *)eff_buf.token,
  97                                                              eff_buf.token_len);
  98                         if (n < 0) {
  99                                 lwsl_info("closing from POLLOUT spill\n");
 100                                 return -1;
 101                         }
 102                         /*
 103                          * Keep amount spilled small to minimize chance of this
 104                          */
 105                         if (n != eff_buf.token_len) {
 106                                 lwsl_err("Unable to spill ext %d vs %s\n",
 107                                                           eff_buf.token_len, n);
 108                                 return -1;
 109                         }
 110                 } else
 111                         continue;
 112
 113                 /* no extension has more to spill */
 114
 115                 if (!ret)
 116                         continue;
 117
 118                 /*
 119                  * There's more to spill from an extension, but we just sent
 120                  * something... did that leave the pipe choked?
 121                  */
 122
 123                 if (!lws_send_pipe_choked(wsi))
 124                         /* no we could add more */
 125                         continue;
 126
 127                 lwsl_info("choked in POLLOUT service\n");
 128
 129                 /*
 130                  * Yes, he's choked.  Leave the POLLOUT masked on so we will
 131                  * come back here when he is unchoked.  Don't call the user
 132                  * callback to enforce ordering of spilling, he'll get called
 133                  * when we come back here and there's nothing more to spill.
 134                  */
 135
 136                 return 0;
 137         }
 138 #ifndef LWS_NO_EXTENSIONS
 139         wsi->extension_data_pending = 0;
 140
 141 user_service:
 142 #endif
 143         /* one shot */
 144
 145         if (pollfd) {
 146                 if (lws_change_pollfd(wsi, LWS_POLLOUT, 0))
 147                         return 1;
 148
 149                 lws_libev_io(context, wsi, LWS_EV_STOP | LWS_EV_WRITE);
 150         }
 151
 152 notify_action:
 153         if (wsi->mode == LWS_CONNMODE_WS_CLIENT)
 154                 n = LWS_CALLBACK_CLIENT_WRITEABLE;
 155         else
 156                 n = LWS_CALLBACK_SERVER_WRITEABLE;
 157
 158         return user_callback_handle_rxflow(wsi->protocol->callback, context,
 159                         wsi, (enum libwebsocket_callback_reasons) n,
 160                                                       wsi->user_space, NULL, 0);
 161 }
 162
 163
 164
 165 int
 166 libwebsocket_service_timeout_check(struct libwebsocket_context *context,
 167                                      struct libwebsocket *wsi, unsigned int sec)
 168 {
 169         /*
 170          * if extensions want in on it (eg, we are a mux parent)
 171          * give them a chance to service child timeouts
 172          */
 173         if (lws_ext_callback_for_each_active(wsi, LWS_EXT_CALLBACK_1HZ, NULL, sec) < 0)
 174                 return 0;
 175
 176         if (!wsi->pending_timeout)
 177                 return 0;
 178
 179         /*
 180          * if we went beyond the allowed time, kill the
 181          * connection
 182          */
 183         if (sec > wsi->pending_timeout_limit) {
 184                 lwsl_info("TIMEDOUT WAITING on %d\n", wsi->pending_timeout);
 185                 libwebsocket_close_and_free_session(context,
 186                                                 wsi, LWS_CLOSE_STATUS_NOSTATUS);
 187                 return 1;
 188         }
 189
 190         return 0;
 191 }
 192
 193 /**
 194  * libwebsocket_service_fd() - Service polled socket with something waiting
 195  * @context:    Websocket context
 196  * @pollfd:     The pollfd entry describing the socket fd and which events
 197  *              happened.
 198  *
 199  *      This function takes a pollfd that has POLLIN or POLLOUT activity and
 200  *      services it according to the state of the associated
 201  *      struct libwebsocket.
 202  *
 203  *      The one call deals with all "service" that might happen on a socket
 204  *      including listen accepts, http files as well as websocket protocol.
 205  *
 206  *      If a pollfd says it has something, you can just pass it to
 207  *      libwebsocket_serice_fd() whether it is a socket handled by lws or not.
 208  *      If it sees it is a lws socket, the traffic will be handled and
 209  *      pollfd->revents will be zeroed now.
 210  *
 211  *      If the socket is foreign to lws, it leaves revents alone.  So you can
 212  *      see if you should service yourself by checking the pollfd revents
 213  *      after letting lws try to service it.
 214  */
 215
 216 LWS_VISIBLE int
 217 libwebsocket_service_fd(struct libwebsocket_context *context,
 218                                                           struct libwebsocket_pollfd *pollfd)
 219 {
 220         struct libwebsocket *wsi;
 221         int n;
 222         int m;
 223         int listen_socket_fds_index = 0;
 224         time_t now;
 225         int timed_out = 0;
 226         int our_fd = 0;
 227         char draining_flow = 0;
 228         int more;
 229         struct lws_tokens eff_buf;
 230
 231         if (context->listen_service_fd)
 232                 listen_socket_fds_index = context->lws_lookup[
 233                              context->listen_service_fd]->position_in_fds_table;
 234
 235         /*
 236          * you can call us with pollfd = NULL to just allow the once-per-second
 237          * global timeout checks; if less than a second since the last check
 238          * it returns immediately then.
 239          */
 240
 241         time(&now);
 242
 243         /* TODO: if using libev, we should probably use timeout watchers... */
 244         if (context->last_timeout_check_s != now) {
 245                 context->last_timeout_check_s = now;
 246
 247                 lws_plat_service_periodic(context);
 248
 249                 /* global timeout check once per second */
 250
 251                 if (pollfd)
 252                         our_fd = pollfd->fd;
 253
 254                 for (n = 0; n < context->fds_count; n++) {
 255                         m = context->fds[n].fd;
 256                         wsi = context->lws_lookup[m];
 257                         if (!wsi)
 258                                 continue;
 259
 260                         if (libwebsocket_service_timeout_check(context, wsi, now))
 261                                 /* he did time out... */
 262                                 if (m == our_fd) {
 263                                         /* it was the guy we came to service! */
 264                                         timed_out = 1;
 265                                         /* mark as handled */
 266                                         pollfd->revents = 0;
 267                                 }
 268                 }
 269         }
 270
 271         /* the socket we came to service timed out, nothing to do */
 272         if (timed_out)
 273                 return 0;
 274
 275         /* just here for timeout management? */
 276         if (pollfd == NULL)
 277                 return 0;
 278
 279         /* no, here to service a socket descriptor */
 280         wsi = context->lws_lookup[pollfd->fd];
 281         if (wsi == NULL)
 282                 /* not lws connection ... leave revents alone and return */
 283                 return 0;
 284
 285         /*
 286          * so that caller can tell we handled, past here we need to
 287          * zero down pollfd->revents after handling
 288          */
 289
 290         /*
 291          * deal with listen service piggybacking
 292          * every listen_service_modulo services of other fds, we
 293          * sneak one in to service the listen socket if there's anything waiting
 294          *
 295          * To handle connection storms, as found in ab, if we previously saw a
 296          * pending connection here, it causes us to check again next time.
 297          */
 298
 299         if (context->listen_service_fd && pollfd !=
 300                                        &context->fds[listen_socket_fds_index]) {
 301                 context->listen_service_count++;
 302                 if (context->listen_service_extraseen ||
 303                                 context->listen_service_count ==
 304                                                context->listen_service_modulo) {
 305                         context->listen_service_count = 0;
 306                         m = 1;
 307                         if (context->listen_service_extraseen > 5)
 308                                 m = 2;
 309                         while (m--) {
 310                                 /*
 311                                  * even with extpoll, we prepared this
 312                                  * internal fds for listen
 313                                  */
 314                                 n = lws_poll_listen_fd(&context->fds[listen_socket_fds_index]);
 315                                 if (n > 0) { /* there's a conn waiting for us */
 316                                         libwebsocket_service_fd(context,
 317                                                 &context->
 318                                                   fds[listen_socket_fds_index]);
 319                                         context->listen_service_extraseen++;
 320                                 } else {
 321                                         if (context->listen_service_extraseen)
 322                                                 context->
 323                                                      listen_service_extraseen--;
 324                                         break;
 325                                 }
 326                         }
 327                 }
 328
 329         }
 330
 331         /* handle session socket closed */
 332
 333         if ((!(pollfd->revents & LWS_POLLIN)) &&
 334                         (pollfd->revents & LWS_POLLHUP)) {
 335
 336                 lwsl_debug("Session Socket %p (fd=%d) dead\n",
 337                                                        (void *)wsi, pollfd->fd);
 338
 339                 goto close_and_handled;
 340         }
 341
 342         /* okay, what we came here to do... */
 343
 344         switch (wsi->mode) {
 345         case LWS_CONNMODE_HTTP_SERVING:
 346         case LWS_CONNMODE_HTTP_SERVING_ACCEPTED:
 347         case LWS_CONNMODE_SERVER_LISTENER:
 348         case LWS_CONNMODE_SSL_ACK_PENDING:
 349                 n = lws_server_socket_service(context, wsi, pollfd);
 350                 if (n < 0)
 351                         goto close_and_handled;
 352                 goto handled;
 353
 354         case LWS_CONNMODE_WS_SERVING:
 355         case LWS_CONNMODE_WS_CLIENT:
 356
 357                 /* the guy requested a callback when it was OK to write */
 358
 359                 if ((pollfd->revents & LWS_POLLOUT) &&
 360                         (wsi->state == WSI_STATE_ESTABLISHED ||
 361                                 wsi->state == WSI_STATE_FLUSHING_STORED_SEND_BEFORE_CLOSE) &&
 362                            lws_handle_POLLOUT_event(context, wsi, pollfd)) {
 363                         lwsl_info("libwebsocket_service_fd: closing\n");
 364                         goto close_and_handled;
 365                 }
 366
 367                 if (wsi->u.ws.rxflow_buffer &&
 368                               (wsi->u.ws.rxflow_change_to & LWS_RXFLOW_ALLOW)) {
 369                         lwsl_info("draining rxflow\n");
 370                         /* well, drain it */
 371                         eff_buf.token = (char *)wsi->u.ws.rxflow_buffer +
 372                                                 wsi->u.ws.rxflow_pos;
 373                         eff_buf.token_len = wsi->u.ws.rxflow_len -
 374                                                 wsi->u.ws.rxflow_pos;
 375                         draining_flow = 1;
 376                         goto drain;
 377                 }
 378
 379                 /* any incoming data ready? */
 380
 381                 if (!(pollfd->revents & LWS_POLLIN))
 382                         break;
 383
 384 read_pending:
 385                 eff_buf.token_len = lws_ssl_capable_read(wsi,
 386                                 context->service_buffer,
 387                                                sizeof(context->service_buffer));
 388                 switch (eff_buf.token_len) {
 389                 case 0:
 390                         lwsl_info("service_fd: closing due to 0 length read\n");
 391                         goto close_and_handled;
 392                 case LWS_SSL_CAPABLE_ERROR:
 393                         n = 0;
 394                         goto handled;
 395                 case LWS_SSL_CAPABLE_MORE_SERVICE:
 396                         goto close_and_handled;
 397                 }
 398
 399                 /*
 400                  * give any active extensions a chance to munge the buffer
 401                  * before parse.  We pass in a pointer to an lws_tokens struct
 402                  * prepared with the default buffer and content length that's in
 403                  * there.  Rather than rewrite the default buffer, extensions
 404                  * that expect to grow the buffer can adapt .token to
 405                  * point to their own per-connection buffer in the extension
 406                  * user allocation.  By default with no extensions or no
 407                  * extension callback handling, just the normal input buffer is
 408                  * used then so it is efficient.
 409                  */
 410
 411                 eff_buf.token = (char *)context->service_buffer;
 412 drain:
 413
 414                 do {
 415
 416                         more = 0;
 417
 418                         m = lws_ext_callback_for_each_active(wsi,
 419                                 LWS_EXT_CALLBACK_PACKET_RX_PREPARSE, &eff_buf, 0);
 420                         if (m < 0)
 421                                 goto close_and_handled;
 422                         if (m)
 423                                 more = 1;
 424
 425                         /* service incoming data */
 426
 427                         if (eff_buf.token_len) {
 428                                 n = libwebsocket_read(context, wsi,
 429                                         (unsigned char *)eff_buf.token,
 430                                                             eff_buf.token_len);
 431                                 if (n < 0) {
 432                                         /* we closed wsi */
 433                                         n = 0;
 434                                         goto handled;
 435                                 }
 436                         }
 437
 438                         eff_buf.token = NULL;
 439                         eff_buf.token_len = 0;
 440                 } while (more);
 441
 442                 if (draining_flow && wsi->u.ws.rxflow_buffer &&
 443                                  wsi->u.ws.rxflow_pos == wsi->u.ws.rxflow_len) {
 444                         lwsl_info("flow buffer: drained\n");
 445                         free(wsi->u.ws.rxflow_buffer);
 446                         wsi->u.ws.rxflow_buffer = NULL;
 447                         /* having drained the rxflow buffer, can rearm POLLIN */
 448                         n = _libwebsocket_rx_flow_control(wsi); /* n ignored, needed for NO_SERVER case */
 449                 }
 450
 451                 if (lws_ssl_pending(wsi))
 452                         goto read_pending;
 453                 break;
 454
 455         default:
 456 #ifdef LWS_NO_CLIENT
 457                 break;
 458 #else
 459                 n = lws_client_socket_service(context, wsi, pollfd);
 460                 goto handled;
 461 #endif
 462         }
 463
 464         n = 0;
 465         goto handled;
 466
 467 close_and_handled:
 468         libwebsocket_close_and_free_session(context, wsi,
 469                                                 LWS_CLOSE_STATUS_NOSTATUS);
 470         n = 1;
 471
 472 handled:
 473         pollfd->revents = 0;
 474         return n;
 475 }
 476
 477 /**
 478  * libwebsocket_service() - Service any pending websocket activity
 479  * @context:    Websocket context
 480  * @timeout_ms: Timeout for poll; 0 means return immediately if nothing needed
 481  *              service otherwise block and service immediately, returning
 482  *              after the timeout if nothing needed service.
 483  *
 484  *      This function deals with any pending websocket traffic, for three
 485  *      kinds of event.  It handles these events on both server and client
 486  *      types of connection the same.
 487  *
 488  *      1) Accept new connections to our context's server
 489  *
 490  *      2) Call the receive callback for incoming frame data received by
 491  *          server or client connections.
 492  *
 493  *      You need to call this service function periodically to all the above
 494  *      functions to happen; if your application is single-threaded you can
 495  *      just call it in your main event loop.
 496  *
 497  *      Alternatively you can fork a new process that asynchronously handles
 498  *      calling this service in a loop.  In that case you are happy if this
 499  *      call blocks your thread until it needs to take care of something and
 500  *      would call it with a large nonzero timeout.  Your loop then takes no
 501  *      CPU while there is nothing happening.
 502  *
 503  *      If you are calling it in a single-threaded app, you don't want it to
 504  *      wait around blocking other things in your loop from happening, so you
 505  *      would call it with a timeout_ms of 0, so it returns immediately if
 506  *      nothing is pending, or as soon as it services whatever was pending.
 507  */
 508
 509 LWS_VISIBLE int
 510 libwebsocket_service(struct libwebsocket_context *context, int timeout_ms)
 511 {
 512         return lws_plat_service(context, timeout_ms);
 513 }
 514