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         /* protocol packets are next */
  52         if (wsi->pps) {
  53                 lwsl_err("servicing pps %d\n", wsi->pps);
  54                 switch (wsi->pps) {
  55                 case LWS_PPS_HTTP2_MY_SETTINGS:
  56                 case LWS_PPS_HTTP2_ACK_SETTINGS:
  57                         lws_http2_do_pps_send(context, wsi);
  58                         break;
  59                 default:
  60                         break;
  61                 }
  62                 wsi->pps = LWS_PPS_NONE;
  63                 libwebsocket_rx_flow_control(wsi, 1);
  64
  65                 return 0; /* leave POLLOUT active */
  66         }
  67
  68         /* pending control packets have next priority */
  69
  70         if (wsi->state == WSI_STATE_ESTABLISHED && wsi->u.ws.ping_payload_len) {
  71                 n = libwebsocket_write(wsi,
  72                                 &wsi->u.ws.ping_payload_buf[
  73                                         LWS_SEND_BUFFER_PRE_PADDING],
  74                                         wsi->u.ws.ping_payload_len,
  75                                                                LWS_WRITE_PONG);
  76                 if (n < 0)
  77                         return -1;
  78                 /* well he is sent, mark him done */
  79                 wsi->u.ws.ping_payload_len = 0;
  80                 /* leave POLLOUT active either way */
  81                 return 0;
  82         }
  83
  84         /* if nothing critical, user can get the callback */
  85
  86         m = lws_ext_callback_for_each_active(wsi, LWS_EXT_CALLBACK_IS_WRITEABLE,
  87                                                                        NULL, 0);
  88         if (handled == 1)
  89                 goto notify_action;
  90 #ifndef LWS_NO_EXTENSIONS
  91         if (!wsi->extension_data_pending || handled == 2)
  92                 goto user_service;
  93 #endif
  94         /*
  95          * check in on the active extensions, see if they
  96          * had pending stuff to spill... they need to get the
  97          * first look-in otherwise sequence will be disordered
  98          *
  99          * NULL, zero-length eff_buf means just spill pending
 100          */
 101
 102         ret = 1;
 103         while (ret == 1) {
 104
 105                 /* default to nobody has more to spill */
 106
 107                 ret = 0;
 108                 eff_buf.token = NULL;
 109                 eff_buf.token_len = 0;
 110
 111                 /* give every extension a chance to spill */
 112
 113                 m = lws_ext_callback_for_each_active(wsi,
 114                                         LWS_EXT_CALLBACK_PACKET_TX_PRESEND,
 115                                                                    &eff_buf, 0);
 116                 if (m < 0) {
 117                         lwsl_err("ext reports fatal error\n");
 118                         return -1;
 119                 }
 120                 if (m)
 121                         /*
 122                          * at least one extension told us he has more
 123                          * to spill, so we will go around again after
 124                          */
 125                         ret = 1;
 126
 127                 /* assuming they gave us something to send, send it */
 128
 129                 if (eff_buf.token_len) {
 130                         n = lws_issue_raw(wsi, (unsigned char *)eff_buf.token,
 131                                                              eff_buf.token_len);
 132                         if (n < 0) {
 133                                 lwsl_info("closing from POLLOUT spill\n");
 134                                 return -1;
 135                         }
 136                         /*
 137                          * Keep amount spilled small to minimize chance of this
 138                          */
 139                         if (n != eff_buf.token_len) {
 140                                 lwsl_err("Unable to spill ext %d vs %s\n",
 141                                                           eff_buf.token_len, n);
 142                                 return -1;
 143                         }
 144                 } else
 145                         continue;
 146
 147                 /* no extension has more to spill */
 148
 149                 if (!ret)
 150                         continue;
 151
 152                 /*
 153                  * There's more to spill from an extension, but we just sent
 154                  * something... did that leave the pipe choked?
 155                  */
 156
 157                 if (!lws_send_pipe_choked(wsi))
 158                         /* no we could add more */
 159                         continue;
 160
 161                 lwsl_info("choked in POLLOUT service\n");
 162
 163                 /*
 164                  * Yes, he's choked.  Leave the POLLOUT masked on so we will
 165                  * come back here when he is unchoked.  Don't call the user
 166                  * callback to enforce ordering of spilling, he'll get called
 167                  * when we come back here and there's nothing more to spill.
 168                  */
 169
 170                 return 0;
 171         }
 172 #ifndef LWS_NO_EXTENSIONS
 173         wsi->extension_data_pending = 0;
 174
 175 user_service:
 176 #endif
 177         /* one shot */
 178
 179         if (pollfd) {
 180                 if (lws_change_pollfd(wsi, LWS_POLLOUT, 0)) {
 181                         lwsl_info("failled at set pollfd\n");
 182                         return 1;
 183                 }
 184
 185                 lws_libev_io(context, wsi, LWS_EV_STOP | LWS_EV_WRITE);
 186         }
 187
 188 notify_action:
 189         if (wsi->mode == LWS_CONNMODE_WS_CLIENT)
 190                 n = LWS_CALLBACK_CLIENT_WRITEABLE;
 191         else
 192                 n = LWS_CALLBACK_SERVER_WRITEABLE;
 193
 194         return user_callback_handle_rxflow(wsi->protocol->callback, context,
 195                         wsi, (enum libwebsocket_callback_reasons) n,
 196                                                       wsi->user_space, NULL, 0);
 197 }
 198
 199
 200
 201 int
 202 libwebsocket_service_timeout_check(struct libwebsocket_context *context,
 203                                      struct libwebsocket *wsi, unsigned int sec)
 204 {
 205         /*
 206          * if extensions want in on it (eg, we are a mux parent)
 207          * give them a chance to service child timeouts
 208          */
 209         if (lws_ext_callback_for_each_active(wsi, LWS_EXT_CALLBACK_1HZ, NULL, sec) < 0)
 210                 return 0;
 211
 212         if (!wsi->pending_timeout)
 213                 return 0;
 214
 215         /*
 216          * if we went beyond the allowed time, kill the
 217          * connection
 218          */
 219         if (sec > wsi->pending_timeout_limit) {
 220                 lwsl_info("TIMEDOUT WAITING on %d\n", wsi->pending_timeout);
 221                 libwebsocket_close_and_free_session(context,
 222                                                 wsi, LWS_CLOSE_STATUS_NOSTATUS);
 223                 return 1;
 224         }
 225
 226         return 0;
 227 }
 228
 229 int lws_rxflow_cache(struct libwebsocket *wsi, unsigned char *buf, int n, int len)
 230 {
 231         /* his RX is flowcontrolled, don't send remaining now */
 232         if (wsi->rxflow_buffer) {
 233                 /* rxflow while we were spilling prev rxflow */
 234                 lwsl_info("stalling in existing rxflow buf\n");
 235                 return 1;
 236         }
 237
 238         /* a new rxflow, buffer it and warn caller */
 239         lwsl_info("new rxflow input buffer len %d\n", len - n);
 240         wsi->rxflow_buffer = (unsigned char *)malloc(len - n);
 241         wsi->rxflow_len = len - n;
 242         wsi->rxflow_pos = 0;
 243         memcpy(wsi->rxflow_buffer, buf + n, len - n);
 244
 245         return 0;
 246 }
 247
 248 /**
 249  * libwebsocket_service_fd() - Service polled socket with something waiting
 250  * @context:    Websocket context
 251  * @pollfd:     The pollfd entry describing the socket fd and which events
 252  *              happened.
 253  *
 254  *      This function takes a pollfd that has POLLIN or POLLOUT activity and
 255  *      services it according to the state of the associated
 256  *      struct libwebsocket.
 257  *
 258  *      The one call deals with all "service" that might happen on a socket
 259  *      including listen accepts, http files as well as websocket protocol.
 260  *
 261  *      If a pollfd says it has something, you can just pass it to
 262  *      libwebsocket_serice_fd() whether it is a socket handled by lws or not.
 263  *      If it sees it is a lws socket, the traffic will be handled and
 264  *      pollfd->revents will be zeroed now.
 265  *
 266  *      If the socket is foreign to lws, it leaves revents alone.  So you can
 267  *      see if you should service yourself by checking the pollfd revents
 268  *      after letting lws try to service it.
 269  */
 270
 271 LWS_VISIBLE int
 272 libwebsocket_service_fd(struct libwebsocket_context *context,
 273                                                           struct libwebsocket_pollfd *pollfd)
 274 {
 275         struct libwebsocket *wsi;
 276         int n;
 277         int m;
 278         int listen_socket_fds_index = 0;
 279         time_t now;
 280         int timed_out = 0;
 281         int our_fd = 0;
 282         char draining_flow = 0;
 283         int more;
 284         struct lws_tokens eff_buf;
 285
 286         if (context->listen_service_fd)
 287                 listen_socket_fds_index = context->lws_lookup[
 288                              context->listen_service_fd]->position_in_fds_table;
 289
 290         /*
 291          * you can call us with pollfd = NULL to just allow the once-per-second
 292          * global timeout checks; if less than a second since the last check
 293          * it returns immediately then.
 294          */
 295
 296         time(&now);
 297
 298         /* TODO: if using libev, we should probably use timeout watchers... */
 299         if (context->last_timeout_check_s != now) {
 300                 context->last_timeout_check_s = now;
 301
 302                 lws_plat_service_periodic(context);
 303
 304                 /* global timeout check once per second */
 305
 306                 if (pollfd)
 307                         our_fd = pollfd->fd;
 308
 309                 for (n = 0; n < context->fds_count; n++) {
 310                         m = context->fds[n].fd;
 311                         wsi = context->lws_lookup[m];
 312                         if (!wsi)
 313                                 continue;
 314
 315                         if (libwebsocket_service_timeout_check(context, wsi, now))
 316                                 /* he did time out... */
 317                                 if (m == our_fd) {
 318                                         /* it was the guy we came to service! */
 319                                         timed_out = 1;
 320                                         /* mark as handled */
 321                                         pollfd->revents = 0;
 322                                 }
 323                 }
 324         }
 325
 326         /* the socket we came to service timed out, nothing to do */
 327         if (timed_out)
 328                 return 0;
 329
 330         /* just here for timeout management? */
 331         if (pollfd == NULL)
 332                 return 0;
 333
 334         /* no, here to service a socket descriptor */
 335         wsi = context->lws_lookup[pollfd->fd];
 336         if (wsi == NULL)
 337                 /* not lws connection ... leave revents alone and return */
 338                 return 0;
 339
 340         /*
 341          * so that caller can tell we handled, past here we need to
 342          * zero down pollfd->revents after handling
 343          */
 344
 345         /*
 346          * deal with listen service piggybacking
 347          * every listen_service_modulo services of other fds, we
 348          * sneak one in to service the listen socket if there's anything waiting
 349          *
 350          * To handle connection storms, as found in ab, if we previously saw a
 351          * pending connection here, it causes us to check again next time.
 352          */
 353
 354         if (context->listen_service_fd && pollfd !=
 355                                        &context->fds[listen_socket_fds_index]) {
 356                 context->listen_service_count++;
 357                 if (context->listen_service_extraseen ||
 358                                 context->listen_service_count ==
 359                                                context->listen_service_modulo) {
 360                         context->listen_service_count = 0;
 361                         m = 1;
 362                         if (context->listen_service_extraseen > 5)
 363                                 m = 2;
 364                         while (m--) {
 365                                 /*
 366                                  * even with extpoll, we prepared this
 367                                  * internal fds for listen
 368                                  */
 369                                 n = lws_poll_listen_fd(&context->fds[listen_socket_fds_index]);
 370                                 if (n > 0) { /* there's a conn waiting for us */
 371                                         libwebsocket_service_fd(context,
 372                                                 &context->
 373                                                   fds[listen_socket_fds_index]);
 374                                         context->listen_service_extraseen++;
 375                                 } else {
 376                                         if (context->listen_service_extraseen)
 377                                                 context->
 378                                                      listen_service_extraseen--;
 379                                         break;
 380                                 }
 381                         }
 382                 }
 383
 384         }
 385
 386         /* handle session socket closed */
 387
 388         if ((!(pollfd->revents & LWS_POLLIN)) &&
 389                         (pollfd->revents & LWS_POLLHUP)) {
 390
 391                 lwsl_debug("Session Socket %p (fd=%d) dead\n",
 392                                                        (void *)wsi, pollfd->fd);
 393
 394                 goto close_and_handled;
 395         }
 396
 397         /* okay, what we came here to do... */
 398
 399         switch (wsi->mode) {
 400         case LWS_CONNMODE_HTTP_SERVING:
 401         case LWS_CONNMODE_HTTP_SERVING_ACCEPTED:
 402         case LWS_CONNMODE_SERVER_LISTENER:
 403         case LWS_CONNMODE_SSL_ACK_PENDING:
 404                 n = lws_server_socket_service(context, wsi, pollfd);
 405                 if (n < 0)
 406                         goto close_and_handled;
 407                 goto handled;
 408
 409         case LWS_CONNMODE_WS_SERVING:
 410         case LWS_CONNMODE_WS_CLIENT:
 411         case LWS_CONNMODE_HTTP2_SERVING:
 412
 413                 /* the guy requested a callback when it was OK to write */
 414
 415                 if ((pollfd->revents & LWS_POLLOUT) &&
 416                         (wsi->state == WSI_STATE_ESTABLISHED || wsi->state == WSI_STATE_HTTP2_ESTABLISHED || wsi->state == WSI_STATE_HTTP2_ESTABLISHED_PRE_SETTINGS ||
 417                                 wsi->state == WSI_STATE_FLUSHING_STORED_SEND_BEFORE_CLOSE) &&
 418                            lws_handle_POLLOUT_event(context, wsi, pollfd)) {
 419                         lwsl_info("libwebsocket_service_fd: closing\n");
 420                         goto close_and_handled;
 421                 }
 422
 423                 if (wsi->rxflow_buffer &&
 424                               (wsi->rxflow_change_to & LWS_RXFLOW_ALLOW)) {
 425                         lwsl_info("draining rxflow\n");
 426                         /* well, drain it */
 427                         eff_buf.token = (char *)wsi->rxflow_buffer +
 428                                                 wsi->rxflow_pos;
 429                         eff_buf.token_len = wsi->rxflow_len - wsi->rxflow_pos;
 430                         draining_flow = 1;
 431                         goto drain;
 432                 }
 433
 434                 /* any incoming data ready? */
 435
 436                 if (!(pollfd->revents & LWS_POLLIN))
 437                         break;
 438
 439 read_pending:
 440                 eff_buf.token_len = lws_ssl_capable_read(wsi,
 441                                 context->service_buffer,
 442                                                sizeof(context->service_buffer));
 443                 switch (eff_buf.token_len) {
 444                 case 0:
 445                         lwsl_info("service_fd: closing due to 0 length read\n");
 446                         goto close_and_handled;
 447                 case LWS_SSL_CAPABLE_MORE_SERVICE:
 448                         lwsl_info("SSL Capable more service\n");
 449                         n = 0;
 450                         goto handled;
 451                 case LWS_SSL_CAPABLE_ERROR:
 452                         lwsl_info("Closing when error\n");
 453                         goto close_and_handled;
 454                 }
 455
 456                 /*
 457                  * give any active extensions a chance to munge the buffer
 458                  * before parse.  We pass in a pointer to an lws_tokens struct
 459                  * prepared with the default buffer and content length that's in
 460                  * there.  Rather than rewrite the default buffer, extensions
 461                  * that expect to grow the buffer can adapt .token to
 462                  * point to their own per-connection buffer in the extension
 463                  * user allocation.  By default with no extensions or no
 464                  * extension callback handling, just the normal input buffer is
 465                  * used then so it is efficient.
 466                  */
 467
 468                 eff_buf.token = (char *)context->service_buffer;
 469 drain:
 470
 471                 do {
 472
 473                         more = 0;
 474
 475                         m = lws_ext_callback_for_each_active(wsi,
 476                                 LWS_EXT_CALLBACK_PACKET_RX_PREPARSE, &eff_buf, 0);
 477                         if (m < 0)
 478                                 goto close_and_handled;
 479                         if (m)
 480                                 more = 1;
 481
 482                         /* service incoming data */
 483
 484                         if (eff_buf.token_len) {
 485                                 n = libwebsocket_read(context, wsi,
 486                                         (unsigned char *)eff_buf.token,
 487                                                             eff_buf.token_len);
 488                                 if (n < 0) {
 489                                         /* we closed wsi */
 490                                         n = 0;
 491                                         goto handled;
 492                                 }
 493                         }
 494
 495                         eff_buf.token = NULL;
 496                         eff_buf.token_len = 0;
 497                 } while (more);
 498
 499                 if (draining_flow && wsi->rxflow_buffer &&
 500                                  wsi->rxflow_pos == wsi->rxflow_len) {
 501                         lwsl_info("flow buffer: drained\n");
 502                         free(wsi->rxflow_buffer);
 503                         wsi->rxflow_buffer = NULL;
 504                         /* having drained the rxflow buffer, can rearm POLLIN */
 505                         n = _libwebsocket_rx_flow_control(wsi); /* n ignored, needed for NO_SERVER case */
 506                 }
 507
 508                 if (lws_ssl_pending(wsi))
 509                         goto read_pending;
 510                 break;
 511
 512         default:
 513 #ifdef LWS_NO_CLIENT
 514                 break;
 515 #else
 516                 n = lws_client_socket_service(context, wsi, pollfd);
 517                 goto handled;
 518 #endif
 519         }
 520
 521         n = 0;
 522         goto handled;
 523
 524 close_and_handled:
 525         lwsl_debug("Close and handled\n");
 526         libwebsocket_close_and_free_session(context, wsi,
 527                                                 LWS_CLOSE_STATUS_NOSTATUS);
 528         n = 1;
 529
 530 handled:
 531         pollfd->revents = 0;
 532         return n;
 533 }
 534
 535 /**
 536  * libwebsocket_service() - Service any pending websocket activity
 537  * @context:    Websocket context
 538  * @timeout_ms: Timeout for poll; 0 means return immediately if nothing needed
 539  *              service otherwise block and service immediately, returning
 540  *              after the timeout if nothing needed service.
 541  *
 542  *      This function deals with any pending websocket traffic, for three
 543  *      kinds of event.  It handles these events on both server and client
 544  *      types of connection the same.
 545  *
 546  *      1) Accept new connections to our context's server
 547  *
 548  *      2) Call the receive callback for incoming frame data received by
 549  *          server or client connections.
 550  *
 551  *      You need to call this service function periodically to all the above
 552  *      functions to happen; if your application is single-threaded you can
 553  *      just call it in your main event loop.
 554  *
 555  *      Alternatively you can fork a new process that asynchronously handles
 556  *      calling this service in a loop.  In that case you are happy if this
 557  *      call blocks your thread until it needs to take care of something and
 558  *      would call it with a large nonzero timeout.  Your loop then takes no
 559  *      CPU while there is nothing happening.
 560  *
 561  *      If you are calling it in a single-threaded app, you don't want it to
 562  *      wait around blocking other things in your loop from happening, so you
 563  *      would call it with a timeout_ms of 0, so it returns immediately if
 564  *      nothing is pending, or as soon as it services whatever was pending.
 565  */
 566
 567 LWS_VISIBLE int
 568 libwebsocket_service(struct libwebsocket_context *context, int timeout_ms)
 569 {
 570         return lws_plat_service(context, timeout_ms);
 571 }
 572