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 static int
  25 lws_calllback_as_writeable(struct libwebsocket_context *context,
  26                    struct libwebsocket *wsi)
  27 {
  28         int n;
  29
  30         switch (wsi->mode) {
  31         case LWS_CONNMODE_WS_CLIENT:
  32                 n = LWS_CALLBACK_CLIENT_WRITEABLE;
  33                 break;
  34         case LWS_CONNMODE_WS_SERVING:
  35                 n = LWS_CALLBACK_SERVER_WRITEABLE;
  36                 break;
  37         default:
  38                 n = LWS_CALLBACK_HTTP_WRITEABLE;
  39                 break;
  40         }
  41         lwsl_info("%s: %p (user=%p)\n", __func__, wsi, wsi->user_space);
  42         return user_callback_handle_rxflow(wsi->protocol->callback, context,
  43                         wsi, (enum libwebsocket_callback_reasons) n,
  44                                                       wsi->user_space, NULL, 0);
  45 }
  46
  47 int
  48 lws_handle_POLLOUT_event(struct libwebsocket_context *context,
  49                    struct libwebsocket *wsi, struct libwebsocket_pollfd *pollfd)
  50 {
  51         int n;
  52         struct lws_tokens eff_buf;
  53 #ifdef LWS_USE_HTTP2
  54         struct libwebsocket *wsi2;
  55 #endif
  56         int ret;
  57         int m;
  58         int handled = 0;
  59
  60         /* pending truncated sends have uber priority */
  61
  62         if (wsi->truncated_send_len) {
  63                 if (lws_issue_raw(wsi, wsi->truncated_send_malloc +
  64                                 wsi->truncated_send_offset,
  65                                                 wsi->truncated_send_len) < 0) {
  66                         lwsl_info("lws_handle_POLLOUT_event signalling to close\n");
  67                         return -1;
  68                 }
  69                 /* leave POLLOUT active either way */
  70                 return 0;
  71         } else
  72                 if (wsi->state == WSI_STATE_FLUSHING_STORED_SEND_BEFORE_CLOSE) {
  73                         lwsl_info("***** %x signalling to close in POLLOUT handler\n", wsi);
  74                         return -1; /* retry closing now */
  75                 }
  76 #ifdef LWS_USE_HTTP2
  77         /* protocol packets are next */
  78         if (wsi->pps) {
  79                 lwsl_info("servicing pps %d\n", wsi->pps);
  80                 switch (wsi->pps) {
  81                 case LWS_PPS_HTTP2_MY_SETTINGS:
  82                 case LWS_PPS_HTTP2_ACK_SETTINGS:
  83                         lws_http2_do_pps_send(context, wsi);
  84                         break;
  85                 default:
  86                         break;
  87                 }
  88                 wsi->pps = LWS_PPS_NONE;
  89                 libwebsocket_rx_flow_control(wsi, 1);
  90
  91                 return 0; /* leave POLLOUT active */
  92         }
  93 #endif
  94         /* pending control packets have next priority */
  95
  96         if (wsi->state == WSI_STATE_ESTABLISHED && wsi->u.ws.ping_payload_len) {
  97                 n = libwebsocket_write(wsi,
  98                                 &wsi->u.ws.ping_payload_buf[
  99                                         LWS_SEND_BUFFER_PRE_PADDING],
 100                                         wsi->u.ws.ping_payload_len,
 101                                                                LWS_WRITE_PONG);
 102                 if (n < 0)
 103                         return -1;
 104                 /* well he is sent, mark him done */
 105                 wsi->u.ws.ping_payload_len = 0;
 106                 /* leave POLLOUT active either way */
 107                 return 0;
 108         }
 109
 110         /* if nothing critical, user can get the callback */
 111
 112         m = lws_ext_callback_for_each_active(wsi, LWS_EXT_CALLBACK_IS_WRITEABLE,
 113                                                                        NULL, 0);
 114         if (handled == 1)
 115                 goto notify_action;
 116 #ifndef LWS_NO_EXTENSIONS
 117         if (!wsi->extension_data_pending || handled == 2)
 118                 goto user_service;
 119 #endif
 120         /*
 121          * check in on the active extensions, see if they
 122          * had pending stuff to spill... they need to get the
 123          * first look-in otherwise sequence will be disordered
 124          *
 125          * NULL, zero-length eff_buf means just spill pending
 126          */
 127
 128         ret = 1;
 129         while (ret == 1) {
 130
 131                 /* default to nobody has more to spill */
 132
 133                 ret = 0;
 134                 eff_buf.token = NULL;
 135                 eff_buf.token_len = 0;
 136
 137                 /* give every extension a chance to spill */
 138
 139                 m = lws_ext_callback_for_each_active(wsi,
 140                                         LWS_EXT_CALLBACK_PACKET_TX_PRESEND,
 141                                                                    &eff_buf, 0);
 142                 if (m < 0) {
 143                         lwsl_err("ext reports fatal error\n");
 144                         return -1;
 145                 }
 146                 if (m)
 147                         /*
 148                          * at least one extension told us he has more
 149                          * to spill, so we will go around again after
 150                          */
 151                         ret = 1;
 152
 153                 /* assuming they gave us something to send, send it */
 154
 155                 if (eff_buf.token_len) {
 156                         n = lws_issue_raw(wsi, (unsigned char *)eff_buf.token,
 157                                                              eff_buf.token_len);
 158                         if (n < 0) {
 159                                 lwsl_info("closing from POLLOUT spill\n");
 160                                 return -1;
 161                         }
 162                         /*
 163                          * Keep amount spilled small to minimize chance of this
 164                          */
 165                         if (n != eff_buf.token_len) {
 166                                 lwsl_err("Unable to spill ext %d vs %s\n",
 167                                                           eff_buf.token_len, n);
 168                                 return -1;
 169                         }
 170                 } else
 171                         continue;
 172
 173                 /* no extension has more to spill */
 174
 175                 if (!ret)
 176                         continue;
 177
 178                 /*
 179                  * There's more to spill from an extension, but we just sent
 180                  * something... did that leave the pipe choked?
 181                  */
 182
 183                 if (!lws_send_pipe_choked(wsi))
 184                         /* no we could add more */
 185                         continue;
 186
 187                 lwsl_info("choked in POLLOUT service\n");
 188
 189                 /*
 190                  * Yes, he's choked.  Leave the POLLOUT masked on so we will
 191                  * come back here when he is unchoked.  Don't call the user
 192                  * callback to enforce ordering of spilling, he'll get called
 193                  * when we come back here and there's nothing more to spill.
 194                  */
 195
 196                 return 0;
 197         }
 198 #ifndef LWS_NO_EXTENSIONS
 199         wsi->extension_data_pending = 0;
 200
 201 user_service:
 202 #endif
 203         /* one shot */
 204
 205         if (pollfd) {
 206                 if (lws_change_pollfd(wsi, LWS_POLLOUT, 0)) {
 207                         lwsl_info("failled at set pollfd\n");
 208                         return 1;
 209                 }
 210
 211                 lws_libev_io(context, wsi, LWS_EV_STOP | LWS_EV_WRITE);
 212         }
 213
 214 notify_action:
 215 #ifdef LWS_USE_HTTP2
 216         /*
 217          * we are the 'network wsi' for potentially many muxed child wsi with
 218          * no network connection of their own, who have to use us for all their
 219          * network actions.  So we use a round-robin scheme to share out the
 220          * POLLOUT notifications to our children.
 221          *
 222          * But because any child could exhaust the socket's ability to take
 223          * writes, we can only let one child get notified each time.
 224          *
 225          * In addition children may be closed / deleted / added between POLLOUT
 226          * notifications, so we can't hold pointers
 227          */
 228
 229         if (wsi->mode != LWS_CONNMODE_HTTP2_SERVING) {
 230                 lwsl_info("%s: non http2\n", __func__);
 231                 goto notify;
 232         }
 233
 234         wsi->u.http2.requested_POLLOUT = 0;
 235         if (!wsi->u.http2.initialized) {
 236                 lwsl_info("pollout on uninitialized http2 conn\n");
 237                 return 0;
 238         }
 239
 240         lwsl_info("%s: doing children\n", __func__);
 241
 242         wsi2 = wsi;
 243         do {
 244                 wsi2 = wsi2->u.http2.next_child_wsi;
 245                 lwsl_info("%s: child %p\n", __func__, wsi2);
 246                 if (!wsi2)
 247                         continue;
 248                 if (!wsi2->u.http2.requested_POLLOUT)
 249                         continue;
 250                 wsi2->u.http2.requested_POLLOUT = 0;
 251                 if (lws_calllback_as_writeable(context, wsi2)) {
 252                         lwsl_debug("Closing POLLOUT child\n");
 253                         libwebsocket_close_and_free_session(context, wsi2,
 254                                                 LWS_CLOSE_STATUS_NOSTATUS);
 255                 }
 256                 wsi2 = wsi;
 257         } while (wsi2 != NULL && !lws_send_pipe_choked(wsi));
 258
 259         lwsl_info("%s: completed\n", __func__);
 260
 261         return 0;
 262 notify:
 263 #endif
 264         return lws_calllback_as_writeable(context, wsi);
 265 }
 266
 267
 268
 269 int
 270 libwebsocket_service_timeout_check(struct libwebsocket_context *context,
 271                                      struct libwebsocket *wsi, unsigned int sec)
 272 {
 273         /*
 274          * if extensions want in on it (eg, we are a mux parent)
 275          * give them a chance to service child timeouts
 276          */
 277         if (lws_ext_callback_for_each_active(wsi, LWS_EXT_CALLBACK_1HZ, NULL, sec) < 0)
 278                 return 0;
 279
 280         if (!wsi->pending_timeout)
 281                 return 0;
 282
 283         /*
 284          * if we went beyond the allowed time, kill the
 285          * connection
 286          */
 287         if (sec > wsi->pending_timeout_limit) {
 288                 lwsl_info("TIMEDOUT WAITING on %d\n", wsi->pending_timeout);
 289                 libwebsocket_close_and_free_session(context,
 290                                                 wsi, LWS_CLOSE_STATUS_NOSTATUS);
 291                 return 1;
 292         }
 293
 294         return 0;
 295 }
 296
 297 int lws_rxflow_cache(struct libwebsocket *wsi, unsigned char *buf, int n, int len)
 298 {
 299         /* his RX is flowcontrolled, don't send remaining now */
 300         if (wsi->rxflow_buffer) {
 301                 /* rxflow while we were spilling prev rxflow */
 302                 lwsl_info("stalling in existing rxflow buf\n");
 303                 return 1;
 304         }
 305
 306         /* a new rxflow, buffer it and warn caller */
 307         lwsl_info("new rxflow input buffer len %d\n", len - n);
 308         wsi->rxflow_buffer = (unsigned char *)malloc(len - n);
 309         wsi->rxflow_len = len - n;
 310         wsi->rxflow_pos = 0;
 311         memcpy(wsi->rxflow_buffer, buf + n, len - n);
 312
 313         return 0;
 314 }
 315
 316 /**
 317  * libwebsocket_service_fd() - Service polled socket with something waiting
 318  * @context:    Websocket context
 319  * @pollfd:     The pollfd entry describing the socket fd and which events
 320  *              happened.
 321  *
 322  *      This function takes a pollfd that has POLLIN or POLLOUT activity and
 323  *      services it according to the state of the associated
 324  *      struct libwebsocket.
 325  *
 326  *      The one call deals with all "service" that might happen on a socket
 327  *      including listen accepts, http files as well as websocket protocol.
 328  *
 329  *      If a pollfd says it has something, you can just pass it to
 330  *      libwebsocket_serice_fd() whether it is a socket handled by lws or not.
 331  *      If it sees it is a lws socket, the traffic will be handled and
 332  *      pollfd->revents will be zeroed now.
 333  *
 334  *      If the socket is foreign to lws, it leaves revents alone.  So you can
 335  *      see if you should service yourself by checking the pollfd revents
 336  *      after letting lws try to service it.
 337  */
 338
 339 LWS_VISIBLE int
 340 libwebsocket_service_fd(struct libwebsocket_context *context,
 341                                                           struct libwebsocket_pollfd *pollfd)
 342 {
 343         struct libwebsocket *wsi;
 344         int n;
 345         int m;
 346         int listen_socket_fds_index = 0;
 347         time_t now;
 348         int timed_out = 0;
 349         int our_fd = 0;
 350         char draining_flow = 0;
 351         int more;
 352         struct lws_tokens eff_buf;
 353
 354         if (context->listen_service_fd)
 355                 listen_socket_fds_index = context->lws_lookup[
 356                              context->listen_service_fd]->position_in_fds_table;
 357
 358         /*
 359          * you can call us with pollfd = NULL to just allow the once-per-second
 360          * global timeout checks; if less than a second since the last check
 361          * it returns immediately then.
 362          */
 363
 364         time(&now);
 365
 366         /* TODO: if using libev, we should probably use timeout watchers... */
 367         if (context->last_timeout_check_s != now) {
 368                 context->last_timeout_check_s = now;
 369
 370                 lws_plat_service_periodic(context);
 371
 372                 /* global timeout check once per second */
 373
 374                 if (pollfd)
 375                         our_fd = pollfd->fd;
 376
 377                 for (n = 0; n < context->fds_count; n++) {
 378                         m = context->fds[n].fd;
 379                         wsi = context->lws_lookup[m];
 380                         if (!wsi)
 381                                 continue;
 382
 383                         if (libwebsocket_service_timeout_check(context, wsi, now))
 384                                 /* he did time out... */
 385                                 if (m == our_fd) {
 386                                         /* it was the guy we came to service! */
 387                                         timed_out = 1;
 388                                         /* mark as handled */
 389                                         pollfd->revents = 0;
 390                                 }
 391                 }
 392         }
 393
 394         /* the socket we came to service timed out, nothing to do */
 395         if (timed_out)
 396                 return 0;
 397
 398         /* just here for timeout management? */
 399         if (pollfd == NULL)
 400                 return 0;
 401
 402         /* no, here to service a socket descriptor */
 403         wsi = context->lws_lookup[pollfd->fd];
 404         if (wsi == NULL)
 405                 /* not lws connection ... leave revents alone and return */
 406                 return 0;
 407
 408         /*
 409          * so that caller can tell we handled, past here we need to
 410          * zero down pollfd->revents after handling
 411          */
 412
 413         /*
 414          * deal with listen service piggybacking
 415          * every listen_service_modulo services of other fds, we
 416          * sneak one in to service the listen socket if there's anything waiting
 417          *
 418          * To handle connection storms, as found in ab, if we previously saw a
 419          * pending connection here, it causes us to check again next time.
 420          */
 421
 422         if (context->listen_service_fd && pollfd !=
 423                                        &context->fds[listen_socket_fds_index]) {
 424                 context->listen_service_count++;
 425                 if (context->listen_service_extraseen ||
 426                                 context->listen_service_count ==
 427                                                context->listen_service_modulo) {
 428                         context->listen_service_count = 0;
 429                         m = 1;
 430                         if (context->listen_service_extraseen > 5)
 431                                 m = 2;
 432                         while (m--) {
 433                                 /*
 434                                  * even with extpoll, we prepared this
 435                                  * internal fds for listen
 436                                  */
 437                                 n = lws_poll_listen_fd(&context->fds[listen_socket_fds_index]);
 438                                 if (n > 0) { /* there's a conn waiting for us */
 439                                         libwebsocket_service_fd(context,
 440                                                 &context->
 441                                                   fds[listen_socket_fds_index]);
 442                                         context->listen_service_extraseen++;
 443                                 } else {
 444                                         if (context->listen_service_extraseen)
 445                                                 context->
 446                                                      listen_service_extraseen--;
 447                                         break;
 448                                 }
 449                         }
 450                 }
 451
 452         }
 453
 454         /* handle session socket closed */
 455
 456         if ((!(pollfd->revents & LWS_POLLIN)) &&
 457                         (pollfd->revents & LWS_POLLHUP)) {
 458
 459                 lwsl_debug("Session Socket %p (fd=%d) dead\n",
 460                                                        (void *)wsi, pollfd->fd);
 461
 462                 goto close_and_handled;
 463         }
 464
 465         /* okay, what we came here to do... */
 466
 467         switch (wsi->mode) {
 468         case LWS_CONNMODE_HTTP_SERVING:
 469         case LWS_CONNMODE_HTTP_SERVING_ACCEPTED:
 470         case LWS_CONNMODE_SERVER_LISTENER:
 471         case LWS_CONNMODE_SSL_ACK_PENDING:
 472                 n = lws_server_socket_service(context, wsi, pollfd);
 473                 if (n < 0)
 474                         goto close_and_handled;
 475                 goto handled;
 476
 477         case LWS_CONNMODE_WS_SERVING:
 478         case LWS_CONNMODE_WS_CLIENT:
 479         case LWS_CONNMODE_HTTP2_SERVING:
 480
 481                 /* the guy requested a callback when it was OK to write */
 482
 483                 if ((pollfd->revents & LWS_POLLOUT) &&
 484                         (wsi->state == WSI_STATE_ESTABLISHED || wsi->state == WSI_STATE_HTTP2_ESTABLISHED || wsi->state == WSI_STATE_HTTP2_ESTABLISHED_PRE_SETTINGS ||
 485                                 wsi->state == WSI_STATE_FLUSHING_STORED_SEND_BEFORE_CLOSE) &&
 486                            lws_handle_POLLOUT_event(context, wsi, pollfd)) {
 487                         lwsl_info("libwebsocket_service_fd: closing\n");
 488                         goto close_and_handled;
 489                 }
 490
 491                 if (wsi->rxflow_buffer &&
 492                               (wsi->rxflow_change_to & LWS_RXFLOW_ALLOW)) {
 493                         lwsl_info("draining rxflow\n");
 494                         /* well, drain it */
 495                         eff_buf.token = (char *)wsi->rxflow_buffer +
 496                                                 wsi->rxflow_pos;
 497                         eff_buf.token_len = wsi->rxflow_len - wsi->rxflow_pos;
 498                         draining_flow = 1;
 499                         goto drain;
 500                 }
 501
 502                 /* any incoming data ready? */
 503
 504                 if (!(pollfd->revents & LWS_POLLIN))
 505                         break;
 506
 507                 eff_buf.token_len = lws_ssl_capable_read(context, wsi,
 508                                 context->service_buffer,
 509                                                sizeof(context->service_buffer));
 510                 switch (eff_buf.token_len) {
 511                 case 0:
 512                         lwsl_info("service_fd: closing due to 0 length read\n");
 513                         goto close_and_handled;
 514                 case LWS_SSL_CAPABLE_MORE_SERVICE:
 515                         lwsl_info("SSL Capable more service\n");
 516                         n = 0;
 517                         goto handled;
 518                 case LWS_SSL_CAPABLE_ERROR:
 519                         lwsl_info("Closing when error\n");
 520                         goto close_and_handled;
 521                 }
 522
 523                 /*
 524                  * give any active extensions a chance to munge the buffer
 525                  * before parse.  We pass in a pointer to an lws_tokens struct
 526                  * prepared with the default buffer and content length that's in
 527                  * there.  Rather than rewrite the default buffer, extensions
 528                  * that expect to grow the buffer can adapt .token to
 529                  * point to their own per-connection buffer in the extension
 530                  * user allocation.  By default with no extensions or no
 531                  * extension callback handling, just the normal input buffer is
 532                  * used then so it is efficient.
 533                  */
 534
 535                 eff_buf.token = (char *)context->service_buffer;
 536 drain:
 537
 538                 do {
 539
 540                         more = 0;
 541
 542                         m = lws_ext_callback_for_each_active(wsi,
 543                                 LWS_EXT_CALLBACK_PACKET_RX_PREPARSE, &eff_buf, 0);
 544                         if (m < 0)
 545                                 goto close_and_handled;
 546                         if (m)
 547                                 more = 1;
 548
 549                         /* service incoming data */
 550
 551                         if (eff_buf.token_len) {
 552                                 n = libwebsocket_read(context, wsi,
 553                                         (unsigned char *)eff_buf.token,
 554                                                             eff_buf.token_len);
 555                                 if (n < 0) {
 556                                         /* we closed wsi */
 557                                         n = 0;
 558                                         goto handled;
 559                                 }
 560                         }
 561
 562                         eff_buf.token = NULL;
 563                         eff_buf.token_len = 0;
 564                 } while (more);
 565
 566                 if (draining_flow && wsi->rxflow_buffer &&
 567                                  wsi->rxflow_pos == wsi->rxflow_len) {
 568                         lwsl_info("flow buffer: drained\n");
 569                         free(wsi->rxflow_buffer);
 570                         wsi->rxflow_buffer = NULL;
 571                         /* having drained the rxflow buffer, can rearm POLLIN */
 572                         _libwebsocket_rx_flow_control(wsi); /* n ignored, needed for NO_SERVER case */
 573                 }
 574
 575                 break;
 576
 577         default:
 578 #ifdef LWS_NO_CLIENT
 579                 break;
 580 #else
 581                 n = lws_client_socket_service(context, wsi, pollfd);
 582                 goto handled;
 583 #endif
 584         }
 585
 586         n = 0;
 587         goto handled;
 588
 589 close_and_handled:
 590         lwsl_debug("Close and handled\n");
 591         libwebsocket_close_and_free_session(context, wsi,
 592                                                 LWS_CLOSE_STATUS_NOSTATUS);
 593         n = 1;
 594
 595 handled:
 596         pollfd->revents = 0;
 597         return n;
 598 }
 599
 600 /**
 601  * libwebsocket_service() - Service any pending websocket activity
 602  * @context:    Websocket context
 603  * @timeout_ms: Timeout for poll; 0 means return immediately if nothing needed
 604  *              service otherwise block and service immediately, returning
 605  *              after the timeout if nothing needed service.
 606  *
 607  *      This function deals with any pending websocket traffic, for three
 608  *      kinds of event.  It handles these events on both server and client
 609  *      types of connection the same.
 610  *
 611  *      1) Accept new connections to our context's server
 612  *
 613  *      2) Call the receive callback for incoming frame data received by
 614  *          server or client connections.
 615  *
 616  *      You need to call this service function periodically to all the above
 617  *      functions to happen; if your application is single-threaded you can
 618  *      just call it in your main event loop.
 619  *
 620  *      Alternatively you can fork a new process that asynchronously handles
 621  *      calling this service in a loop.  In that case you are happy if this
 622  *      call blocks your thread until it needs to take care of something and
 623  *      would call it with a large nonzero timeout.  Your loop then takes no
 624  *      CPU while there is nothing happening.
 625  *
 626  *      If you are calling it in a single-threaded app, you don't want it to
 627  *      wait around blocking other things in your loop from happening, so you
 628  *      would call it with a timeout_ms of 0, so it returns immediately if
 629  *      nothing is pending, or as soon as it services whatever was pending.
 630  */
 631
 632 LWS_VISIBLE int
 633 libwebsocket_service(struct libwebsocket_context *context, int timeout_ms)
 634 {
 635         return lws_plat_service(context, timeout_ms);
 636 }
 637