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 write_type = LWS_WRITE_PONG;
  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 &&
  97             wsi->u.ws.ping_pending_flag) {
  98
  99                 if (wsi->u.ws.payload_is_close)
 100                         write_type = LWS_WRITE_CLOSE;
 101
 102                 n = libwebsocket_write(wsi,
 103                                 &wsi->u.ws.ping_payload_buf[
 104                                         LWS_SEND_BUFFER_PRE_PADDING],
 105                                         wsi->u.ws.ping_payload_len,
 106                                                                write_type);
 107                 if (n < 0)
 108                         return -1;
 109
 110                 /* well he is sent, mark him done */
 111                 wsi->u.ws.ping_pending_flag = 0;
 112                 if (wsi->u.ws.payload_is_close)
 113                         /* oh... a close frame was it... then we are done */
 114                         return -1;
 115
 116                 /* otherwise for PING, leave POLLOUT active either way */
 117                 return 0;
 118         }
 119
 120         /* if nothing critical, user can get the callback */
 121
 122         m = lws_ext_callback_for_each_active(wsi, LWS_EXT_CALLBACK_IS_WRITEABLE,
 123                                                                        NULL, 0);
 124 #ifndef LWS_NO_EXTENSIONS
 125         if (!wsi->extension_data_pending)
 126                 goto user_service;
 127 #endif
 128         /*
 129          * check in on the active extensions, see if they
 130          * had pending stuff to spill... they need to get the
 131          * first look-in otherwise sequence will be disordered
 132          *
 133          * NULL, zero-length eff_buf means just spill pending
 134          */
 135
 136         ret = 1;
 137         while (ret == 1) {
 138
 139                 /* default to nobody has more to spill */
 140
 141                 ret = 0;
 142                 eff_buf.token = NULL;
 143                 eff_buf.token_len = 0;
 144
 145                 /* give every extension a chance to spill */
 146
 147                 m = lws_ext_callback_for_each_active(wsi,
 148                                         LWS_EXT_CALLBACK_PACKET_TX_PRESEND,
 149                                                                    &eff_buf, 0);
 150                 if (m < 0) {
 151                         lwsl_err("ext reports fatal error\n");
 152                         return -1;
 153                 }
 154                 if (m)
 155                         /*
 156                          * at least one extension told us he has more
 157                          * to spill, so we will go around again after
 158                          */
 159                         ret = 1;
 160
 161                 /* assuming they gave us something to send, send it */
 162
 163                 if (eff_buf.token_len) {
 164                         n = lws_issue_raw(wsi, (unsigned char *)eff_buf.token,
 165                                                              eff_buf.token_len);
 166                         if (n < 0) {
 167                                 lwsl_info("closing from POLLOUT spill\n");
 168                                 return -1;
 169                         }
 170                         /*
 171                          * Keep amount spilled small to minimize chance of this
 172                          */
 173                         if (n != eff_buf.token_len) {
 174                                 lwsl_err("Unable to spill ext %d vs %s\n",
 175                                                           eff_buf.token_len, n);
 176                                 return -1;
 177                         }
 178                 } else
 179                         continue;
 180
 181                 /* no extension has more to spill */
 182
 183                 if (!ret)
 184                         continue;
 185
 186                 /*
 187                  * There's more to spill from an extension, but we just sent
 188                  * something... did that leave the pipe choked?
 189                  */
 190
 191                 if (!lws_send_pipe_choked(wsi))
 192                         /* no we could add more */
 193                         continue;
 194
 195                 lwsl_info("choked in POLLOUT service\n");
 196
 197                 /*
 198                  * Yes, he's choked.  Leave the POLLOUT masked on so we will
 199                  * come back here when he is unchoked.  Don't call the user
 200                  * callback to enforce ordering of spilling, he'll get called
 201                  * when we come back here and there's nothing more to spill.
 202                  */
 203
 204                 return 0;
 205         }
 206 #ifndef LWS_NO_EXTENSIONS
 207         wsi->extension_data_pending = 0;
 208
 209 user_service:
 210 #endif
 211         /* one shot */
 212
 213         if (pollfd) {
 214                 if (lws_change_pollfd(wsi, LWS_POLLOUT, 0)) {
 215                         lwsl_info("failled at set pollfd\n");
 216                         return 1;
 217                 }
 218
 219                 lws_libev_io(context, wsi, LWS_EV_STOP | LWS_EV_WRITE);
 220         }
 221
 222 #ifdef LWS_USE_HTTP2
 223         /*
 224          * we are the 'network wsi' for potentially many muxed child wsi with
 225          * no network connection of their own, who have to use us for all their
 226          * network actions.  So we use a round-robin scheme to share out the
 227          * POLLOUT notifications to our children.
 228          *
 229          * But because any child could exhaust the socket's ability to take
 230          * writes, we can only let one child get notified each time.
 231          *
 232          * In addition children may be closed / deleted / added between POLLOUT
 233          * notifications, so we can't hold pointers
 234          */
 235
 236         if (wsi->mode != LWS_CONNMODE_HTTP2_SERVING) {
 237                 lwsl_info("%s: non http2\n", __func__);
 238                 goto notify;
 239         }
 240
 241         wsi->u.http2.requested_POLLOUT = 0;
 242         if (!wsi->u.http2.initialized) {
 243                 lwsl_info("pollout on uninitialized http2 conn\n");
 244                 return 0;
 245         }
 246
 247         lwsl_info("%s: doing children\n", __func__);
 248
 249         wsi2 = wsi;
 250         do {
 251                 wsi2 = wsi2->u.http2.next_child_wsi;
 252                 lwsl_info("%s: child %p\n", __func__, wsi2);
 253                 if (!wsi2)
 254                         continue;
 255                 if (!wsi2->u.http2.requested_POLLOUT)
 256                         continue;
 257                 wsi2->u.http2.requested_POLLOUT = 0;
 258                 if (lws_calllback_as_writeable(context, wsi2)) {
 259                         lwsl_debug("Closing POLLOUT child\n");
 260                         libwebsocket_close_and_free_session(context, wsi2,
 261                                                 LWS_CLOSE_STATUS_NOSTATUS);
 262                 }
 263                 wsi2 = wsi;
 264         } while (wsi2 != NULL && !lws_send_pipe_choked(wsi));
 265
 266         lwsl_info("%s: completed\n", __func__);
 267
 268         return 0;
 269 notify:
 270 #endif
 271         return lws_calllback_as_writeable(context, wsi);
 272 }
 273
 274
 275
 276 int
 277 libwebsocket_service_timeout_check(struct libwebsocket_context *context,
 278                                      struct libwebsocket *wsi, unsigned int sec)
 279 {
 280         /*
 281          * if extensions want in on it (eg, we are a mux parent)
 282          * give them a chance to service child timeouts
 283          */
 284         if (lws_ext_callback_for_each_active(wsi, LWS_EXT_CALLBACK_1HZ, NULL, sec) < 0)
 285                 return 0;
 286
 287         if (!wsi->pending_timeout)
 288                 return 0;
 289
 290         /*
 291          * if we went beyond the allowed time, kill the
 292          * connection
 293          */
 294         if (sec > wsi->pending_timeout_limit) {
 295                 lwsl_info("TIMEDOUT WAITING on %d\n", wsi->pending_timeout);
 296                 /*
 297                  * Since he failed a timeout, he already had a chance to do
 298                  * something and was unable to... that includes situations like
 299                  * half closed connections.  So process this "failed timeout"
 300                  * close as a violent death and don't try to do protocol
 301                  * cleanup like flush partials.
 302                  */
 303                 wsi->socket_is_permanently_unusable = 1;
 304                 libwebsocket_close_and_free_session(context,
 305                                                 wsi, LWS_CLOSE_STATUS_NOSTATUS);
 306                 return 1;
 307         }
 308
 309         return 0;
 310 }
 311
 312 int lws_rxflow_cache(struct libwebsocket *wsi, unsigned char *buf, int n, int len)
 313 {
 314         /* his RX is flowcontrolled, don't send remaining now */
 315         if (wsi->rxflow_buffer) {
 316                 /* rxflow while we were spilling prev rxflow */
 317                 lwsl_info("stalling in existing rxflow buf\n");
 318                 return 1;
 319         }
 320
 321         /* a new rxflow, buffer it and warn caller */
 322         lwsl_info("new rxflow input buffer len %d\n", len - n);
 323         wsi->rxflow_buffer = lws_malloc(len - n);
 324         wsi->rxflow_len = len - n;
 325         wsi->rxflow_pos = 0;
 326         memcpy(wsi->rxflow_buffer, buf + n, len - n);
 327
 328         return 0;
 329 }
 330
 331 /**
 332  * libwebsocket_service_fd() - Service polled socket with something waiting
 333  * @context:    Websocket context
 334  * @pollfd:     The pollfd entry describing the socket fd and which events
 335  *              happened.
 336  *
 337  *      This function takes a pollfd that has POLLIN or POLLOUT activity and
 338  *      services it according to the state of the associated
 339  *      struct libwebsocket.
 340  *
 341  *      The one call deals with all "service" that might happen on a socket
 342  *      including listen accepts, http files as well as websocket protocol.
 343  *
 344  *      If a pollfd says it has something, you can just pass it to
 345  *      libwebsocket_serice_fd() whether it is a socket handled by lws or not.
 346  *      If it sees it is a lws socket, the traffic will be handled and
 347  *      pollfd->revents will be zeroed now.
 348  *
 349  *      If the socket is foreign to lws, it leaves revents alone.  So you can
 350  *      see if you should service yourself by checking the pollfd revents
 351  *      after letting lws try to service it.
 352  */
 353
 354 LWS_VISIBLE int
 355 libwebsocket_service_fd(struct libwebsocket_context *context,
 356                                                           struct libwebsocket_pollfd *pollfd)
 357 {
 358         struct libwebsocket *wsi;
 359         int n;
 360         int m;
 361         int listen_socket_fds_index = 0;
 362         time_t now;
 363         int timed_out = 0;
 364         int our_fd = 0;
 365         char draining_flow = 0;
 366         int more;
 367         struct lws_tokens eff_buf;
 368
 369         if (context->listen_service_fd)
 370                 listen_socket_fds_index = wsi_from_fd(context,context->listen_service_fd)->position_in_fds_table;
 371
 372          /*
 373          * you can call us with pollfd = NULL to just allow the once-per-second
 374          * global timeout checks; if less than a second since the last check
 375          * it returns immediately then.
 376          */
 377
 378         time(&now);
 379
 380         /* TODO: if using libev, we should probably use timeout watchers... */
 381         if (context->last_timeout_check_s != now) {
 382                 context->last_timeout_check_s = now;
 383
 384                 lws_plat_service_periodic(context);
 385
 386                 /* global timeout check once per second */
 387
 388                 if (pollfd)
 389                         our_fd = pollfd->fd;
 390
 391                 for (n = 0; n < context->fds_count; n++) {
 392                         m = context->fds[n].fd;
 393                         wsi = wsi_from_fd(context,m);
 394                         if (!wsi)
 395                                 continue;
 396
 397                         if (libwebsocket_service_timeout_check(context, wsi, now))
 398                                 /* he did time out... */
 399                                 if (m == our_fd) {
 400                                         /* it was the guy we came to service! */
 401                                         timed_out = 1;
 402                                         /* mark as handled */
 403                                         if (pollfd)
 404                                                 pollfd->revents = 0;
 405                                 }
 406                 }
 407         }
 408
 409         /* the socket we came to service timed out, nothing to do */
 410         if (timed_out)
 411                 return 0;
 412
 413         /* just here for timeout management? */
 414         if (pollfd == NULL)
 415                 return 0;
 416
 417         /* no, here to service a socket descriptor */
 418         wsi = wsi_from_fd(context,pollfd->fd);
 419         if (wsi == NULL)
 420                 /* not lws connection ... leave revents alone and return */
 421                 return 0;
 422
 423         /*
 424          * so that caller can tell we handled, past here we need to
 425          * zero down pollfd->revents after handling
 426          */
 427
 428         /*
 429          * deal with listen service piggybacking
 430          * every listen_service_modulo services of other fds, we
 431          * sneak one in to service the listen socket if there's anything waiting
 432          *
 433          * To handle connection storms, as found in ab, if we previously saw a
 434          * pending connection here, it causes us to check again next time.
 435          */
 436
 437         if (context->listen_service_fd && pollfd !=
 438                                        &context->fds[listen_socket_fds_index]) {
 439                 context->listen_service_count++;
 440                 if (context->listen_service_extraseen ||
 441                                 context->listen_service_count ==
 442                                                context->listen_service_modulo) {
 443                         context->listen_service_count = 0;
 444                         m = 1;
 445                         if (context->listen_service_extraseen > 5)
 446                                 m = 2;
 447                         while (m--) {
 448                                 /*
 449                                  * even with extpoll, we prepared this
 450                                  * internal fds for listen
 451                                  */
 452                                 n = lws_poll_listen_fd(&context->fds[listen_socket_fds_index]);
 453                                 if (n > 0) { /* there's a conn waiting for us */
 454                                         libwebsocket_service_fd(context,
 455                                                 &context->
 456                                                   fds[listen_socket_fds_index]);
 457                                         context->listen_service_extraseen++;
 458                                 } else {
 459                                         if (context->listen_service_extraseen)
 460                                                 context->
 461                                                      listen_service_extraseen--;
 462                                         break;
 463                                 }
 464                         }
 465                 }
 466
 467         }
 468
 469         /* handle session socket closed */
 470
 471         if ((!(pollfd->revents & LWS_POLLIN)) &&
 472                         (pollfd->revents & LWS_POLLHUP)) {
 473
 474                 lwsl_debug("Session Socket %p (fd=%d) dead\n",
 475                                                        (void *)wsi, pollfd->fd);
 476
 477                 goto close_and_handled;
 478         }
 479
 480         /* okay, what we came here to do... */
 481
 482         switch (wsi->mode) {
 483         case LWS_CONNMODE_HTTP_SERVING:
 484         case LWS_CONNMODE_HTTP_SERVING_ACCEPTED:
 485         case LWS_CONNMODE_SERVER_LISTENER:
 486         case LWS_CONNMODE_SSL_ACK_PENDING:
 487                 n = lws_server_socket_service(context, wsi, pollfd);
 488                 if (n < 0)
 489                         goto close_and_handled;
 490                 goto handled;
 491
 492         case LWS_CONNMODE_WS_SERVING:
 493         case LWS_CONNMODE_WS_CLIENT:
 494         case LWS_CONNMODE_HTTP2_SERVING:
 495
 496                 /* the guy requested a callback when it was OK to write */
 497
 498                 if ((pollfd->revents & LWS_POLLOUT) &&
 499                     (wsi->state == WSI_STATE_ESTABLISHED ||
 500                      wsi->state == WSI_STATE_HTTP2_ESTABLISHED ||
 501                      wsi->state == WSI_STATE_HTTP2_ESTABLISHED_PRE_SETTINGS ||
 502                      wsi->state == WSI_STATE_RETURNED_CLOSE_ALREADY ||
 503                      wsi->state == WSI_STATE_FLUSHING_STORED_SEND_BEFORE_CLOSE) &&
 504                            lws_handle_POLLOUT_event(context, wsi, pollfd)) {
 505                         lwsl_info("libwebsocket_service_fd: closing\n");
 506                         goto close_and_handled;
 507                 }
 508
 509                 if (wsi->rxflow_buffer &&
 510                               (wsi->rxflow_change_to & LWS_RXFLOW_ALLOW)) {
 511                         lwsl_info("draining rxflow\n");
 512                         /* well, drain it */
 513                         eff_buf.token = (char *)wsi->rxflow_buffer +
 514                                                 wsi->rxflow_pos;
 515                         eff_buf.token_len = wsi->rxflow_len - wsi->rxflow_pos;
 516                         draining_flow = 1;
 517                         goto drain;
 518                 }
 519
 520                 /* any incoming data ready? */
 521
 522                 if (!(pollfd->revents & LWS_POLLIN))
 523                         break;
 524
 525                 eff_buf.token_len = lws_ssl_capable_read(context, wsi,
 526                                 context->service_buffer,
 527                                                sizeof(context->service_buffer));
 528                 switch (eff_buf.token_len) {
 529                 case 0:
 530                         lwsl_info("service_fd: closing due to 0 length read\n");
 531                         goto close_and_handled;
 532                 case LWS_SSL_CAPABLE_MORE_SERVICE:
 533                         lwsl_info("SSL Capable more service\n");
 534                         n = 0;
 535                         goto handled;
 536                 case LWS_SSL_CAPABLE_ERROR:
 537                         lwsl_info("Closing when error\n");
 538                         goto close_and_handled;
 539                 }
 540
 541                 /*
 542                  * give any active extensions a chance to munge the buffer
 543                  * before parse.  We pass in a pointer to an lws_tokens struct
 544                  * prepared with the default buffer and content length that's in
 545                  * there.  Rather than rewrite the default buffer, extensions
 546                  * that expect to grow the buffer can adapt .token to
 547                  * point to their own per-connection buffer in the extension
 548                  * user allocation.  By default with no extensions or no
 549                  * extension callback handling, just the normal input buffer is
 550                  * used then so it is efficient.
 551                  */
 552
 553                 eff_buf.token = (char *)context->service_buffer;
 554 drain:
 555
 556                 do {
 557
 558                         more = 0;
 559
 560                         m = lws_ext_callback_for_each_active(wsi,
 561                                 LWS_EXT_CALLBACK_PACKET_RX_PREPARSE, &eff_buf, 0);
 562                         if (m < 0)
 563                                 goto close_and_handled;
 564                         if (m)
 565                                 more = 1;
 566
 567                         /* service incoming data */
 568
 569                         if (eff_buf.token_len) {
 570                                 n = libwebsocket_read(context, wsi,
 571                                         (unsigned char *)eff_buf.token,
 572                                                             eff_buf.token_len);
 573                                 if (n < 0) {
 574                                         /* we closed wsi */
 575                                         n = 0;
 576                                         goto handled;
 577                                 }
 578                         }
 579
 580                         eff_buf.token = NULL;
 581                         eff_buf.token_len = 0;
 582                 } while (more);
 583
 584                 if (draining_flow && wsi->rxflow_buffer &&
 585                                  wsi->rxflow_pos == wsi->rxflow_len) {
 586                         lwsl_info("flow buffer: drained\n");
 587                         lws_free2(wsi->rxflow_buffer);
 588                         /* having drained the rxflow buffer, can rearm POLLIN */
 589 #ifdef LWS_NO_SERVER
 590                         n =
 591 #endif
 592                         _libwebsocket_rx_flow_control(wsi); /* n ignored, needed for NO_SERVER case */
 593                 }
 594
 595                 break;
 596
 597         default:
 598 #ifdef LWS_NO_CLIENT
 599                 break;
 600 #else
 601                 n = lws_client_socket_service(context, wsi, pollfd);
 602                 goto handled;
 603 #endif
 604         }
 605
 606         n = 0;
 607         goto handled;
 608
 609 close_and_handled:
 610         lwsl_debug("Close and handled\n");
 611         libwebsocket_close_and_free_session(context, wsi,
 612                                                 LWS_CLOSE_STATUS_NOSTATUS);
 613         n = 1;
 614
 615 handled:
 616         pollfd->revents = 0;
 617         return n;
 618 }
 619
 620 /**
 621  * libwebsocket_service() - Service any pending websocket activity
 622  * @context:    Websocket context
 623  * @timeout_ms: Timeout for poll; 0 means return immediately if nothing needed
 624  *              service otherwise block and service immediately, returning
 625  *              after the timeout if nothing needed service.
 626  *
 627  *      This function deals with any pending websocket traffic, for three
 628  *      kinds of event.  It handles these events on both server and client
 629  *      types of connection the same.
 630  *
 631  *      1) Accept new connections to our context's server
 632  *
 633  *      2) Call the receive callback for incoming frame data received by
 634  *          server or client connections.
 635  *
 636  *      You need to call this service function periodically to all the above
 637  *      functions to happen; if your application is single-threaded you can
 638  *      just call it in your main event loop.
 639  *
 640  *      Alternatively you can fork a new process that asynchronously handles
 641  *      calling this service in a loop.  In that case you are happy if this
 642  *      call blocks your thread until it needs to take care of something and
 643  *      would call it with a large nonzero timeout.  Your loop then takes no
 644  *      CPU while there is nothing happening.
 645  *
 646  *      If you are calling it in a single-threaded app, you don't want it to
 647  *      wait around blocking other things in your loop from happening, so you
 648  *      would call it with a timeout_ms of 0, so it returns immediately if
 649  *      nothing is pending, or as soon as it services whatever was pending.
 650  */
 651
 652 LWS_VISIBLE int
 653 libwebsocket_service(struct libwebsocket_context *context, int timeout_ms)
 654 {
 655         return lws_plat_service(context, timeout_ms);
 656 }
 657