lib/service.c

   1 /*
   2  * libwebsockets - small server side websockets and web server implementation
   3  *
   4  * Copyright (C) 2010-2015 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 lws *wsi)
  26 {
  27         int n;
  28
  29         switch (wsi->mode) {
  30         case LWSCM_WS_CLIENT:
  31                 n = LWS_CALLBACK_CLIENT_WRITEABLE;
  32                 break;
  33         case LWSCM_WS_SERVING:
  34                 n = LWS_CALLBACK_SERVER_WRITEABLE;
  35                 break;
  36         default:
  37                 n = LWS_CALLBACK_HTTP_WRITEABLE;
  38                 break;
  39         }
  40         lwsl_debug("%s: %p (user=%p)\n", __func__, wsi, wsi->user_space);
  41         return user_callback_handle_rxflow(wsi->protocol->callback,
  42                                            wsi, (enum lws_callback_reasons) n,
  43                                            wsi->user_space, NULL, 0);
  44 }
  45
  46 int
  47 lws_handle_POLLOUT_event(struct lws *wsi, struct lws_pollfd *pollfd)
  48 {
  49         int write_type = LWS_WRITE_PONG;
  50         struct lws_tokens eff_buf;
  51 #ifdef LWS_USE_HTTP2
  52         struct lws *wsi2;
  53 #endif
  54         int ret, m, n;
  55
  56         /*
  57          * user callback is lowest priority to get these notifications
  58          * actually, since other pending things cannot be disordered
  59          */
  60
  61         /* Priority 1: pending truncated sends are incomplete ws fragments
  62          *             If anything else sent first the protocol would be
  63          *             corrupted.
  64          */
  65         if (wsi->trunc_len) {
  66                 if (lws_issue_raw(wsi, wsi->trunc_alloc + wsi->trunc_offset,
  67                                   wsi->trunc_len) < 0) {
  68                         lwsl_info("%s signalling to close\n", __func__);
  69                         return -1;
  70                 }
  71                 /* leave POLLOUT active either way */
  72                 return 0;
  73         } else
  74                 if (wsi->state == LWSS_FLUSHING_STORED_SEND_BEFORE_CLOSE)
  75                         return -1; /* retry closing now */
  76
  77
  78 #ifdef LWS_USE_HTTP2
  79         /* Priority 2: protocol packets
  80          */
  81         if (wsi->pps) {
  82                 lwsl_info("servicing pps %d\n", wsi->pps);
  83                 switch (wsi->pps) {
  84                 case LWS_PPS_HTTP2_MY_SETTINGS:
  85                 case LWS_PPS_HTTP2_ACK_SETTINGS:
  86                         lws_http2_do_pps_send(lws_get_context(wsi), wsi);
  87                         break;
  88                 default:
  89                         break;
  90                 }
  91                 wsi->pps = LWS_PPS_NONE;
  92                 lws_rx_flow_control(wsi, 1);
  93
  94                 return 0; /* leave POLLOUT active */
  95         }
  96 #endif
  97         /* Priority 3: pending control packets (pong or close)
  98          */
  99         if ((wsi->state == LWSS_ESTABLISHED &&
 100              wsi->u.ws.ping_pending_flag) ||
 101             (wsi->state == LWSS_RETURNED_CLOSE_ALREADY &&
 102              wsi->u.ws.payload_is_close)) {
 103
 104                 if (wsi->u.ws.payload_is_close)
 105                         write_type = LWS_WRITE_CLOSE;
 106
 107                 n = lws_write(wsi, &wsi->u.ws.ping_payload_buf[LWS_PRE],
 108                               wsi->u.ws.ping_payload_len, write_type);
 109                 if (n < 0)
 110                         return -1;
 111
 112                 /* well he is sent, mark him done */
 113                 wsi->u.ws.ping_pending_flag = 0;
 114                 if (wsi->u.ws.payload_is_close)
 115                         /* oh... a close frame was it... then we are done */
 116                         return -1;
 117
 118                 /* otherwise for PING, leave POLLOUT active either way */
 119                 return 0;
 120         }
 121
 122         /* Priority 4: if we are closing, not allowed to send more data frags
 123          *             which means user callback or tx ext flush banned now
 124          */
 125         if (wsi->state == LWSS_RETURNED_CLOSE_ALREADY)
 126                 goto user_service;
 127
 128         /* Priority 5: Tx path extension with more to send
 129          *
 130          *             These are handled as new fragments each time around
 131          *             So while we must block new writeable callback to enforce
 132          *             payload ordering, but since they are always complete
 133          *             fragments control packets can interleave OK.
 134          */
 135         if (wsi->state == LWSS_ESTABLISHED && wsi->u.ws.tx_draining_ext) {
 136                 lwsl_ext("SERVICING TX EXT DRAINING\n");
 137                 if (lws_write(wsi, NULL, 0, LWS_WRITE_CONTINUATION) < 0)
 138                         return -1;
 139                 /* leave POLLOUT active */
 140                 return 0;
 141         }
 142
 143         /* Priority 6: user can get the callback
 144          */
 145         m = lws_ext_cb_active(wsi, LWS_EXT_CB_IS_WRITEABLE, NULL, 0);
 146 #ifndef LWS_NO_EXTENSIONS
 147         if (!wsi->extension_data_pending)
 148                 goto user_service;
 149 #endif
 150         /*
 151          * check in on the active extensions, see if they
 152          * had pending stuff to spill... they need to get the
 153          * first look-in otherwise sequence will be disordered
 154          *
 155          * NULL, zero-length eff_buf means just spill pending
 156          */
 157
 158         ret = 1;
 159         while (ret == 1) {
 160
 161                 /* default to nobody has more to spill */
 162
 163                 ret = 0;
 164                 eff_buf.token = NULL;
 165                 eff_buf.token_len = 0;
 166
 167                 /* give every extension a chance to spill */
 168
 169                 m = lws_ext_cb_active(wsi,
 170                                         LWS_EXT_CB_PACKET_TX_PRESEND,
 171                                                &eff_buf, 0);
 172                 if (m < 0) {
 173                         lwsl_err("ext reports fatal error\n");
 174                         return -1;
 175                 }
 176                 if (m)
 177                         /*
 178                          * at least one extension told us he has more
 179                          * to spill, so we will go around again after
 180                          */
 181                         ret = 1;
 182
 183                 /* assuming they gave us something to send, send it */
 184
 185                 if (eff_buf.token_len) {
 186                         n = lws_issue_raw(wsi, (unsigned char *)eff_buf.token,
 187                                           eff_buf.token_len);
 188                         if (n < 0) {
 189                                 lwsl_info("closing from POLLOUT spill\n");
 190                                 return -1;
 191                         }
 192                         /*
 193                          * Keep amount spilled small to minimize chance of this
 194                          */
 195                         if (n != eff_buf.token_len) {
 196                                 lwsl_err("Unable to spill ext %d vs %s\n",
 197                                                           eff_buf.token_len, n);
 198                                 return -1;
 199                         }
 200                 } else
 201                         continue;
 202
 203                 /* no extension has more to spill */
 204
 205                 if (!ret)
 206                         continue;
 207
 208                 /*
 209                  * There's more to spill from an extension, but we just sent
 210                  * something... did that leave the pipe choked?
 211                  */
 212
 213                 if (!lws_send_pipe_choked(wsi))
 214                         /* no we could add more */
 215                         continue;
 216
 217                 lwsl_info("choked in POLLOUT service\n");
 218
 219                 /*
 220                  * Yes, he's choked.  Leave the POLLOUT masked on so we will
 221                  * come back here when he is unchoked.  Don't call the user
 222                  * callback to enforce ordering of spilling, he'll get called
 223                  * when we come back here and there's nothing more to spill.
 224                  */
 225
 226                 return 0;
 227         }
 228 #ifndef LWS_NO_EXTENSIONS
 229         wsi->extension_data_pending = 0;
 230 #endif
 231 user_service:
 232         /* one shot */
 233
 234         if (pollfd)
 235                 if (lws_change_pollfd(wsi, LWS_POLLOUT, 0)) {
 236                         lwsl_info("failed at set pollfd\n");
 237                         return 1;
 238                 }
 239
 240         if (!wsi->hdr_parsing_completed)
 241                 return 0;
 242
 243 #ifdef LWS_USE_HTTP2
 244         /*
 245          * we are the 'network wsi' for potentially many muxed child wsi with
 246          * no network connection of their own, who have to use us for all their
 247          * network actions.  So we use a round-robin scheme to share out the
 248          * POLLOUT notifications to our children.
 249          *
 250          * But because any child could exhaust the socket's ability to take
 251          * writes, we can only let one child get notified each time.
 252          *
 253          * In addition children may be closed / deleted / added between POLLOUT
 254          * notifications, so we can't hold pointers
 255          */
 256
 257         if (wsi->mode != LWSCM_HTTP2_SERVING) {
 258                 lwsl_info("%s: non http2\n", __func__);
 259                 goto notify;
 260         }
 261
 262         wsi->u.http2.requested_POLLOUT = 0;
 263         if (!wsi->u.http2.initialized) {
 264                 lwsl_info("pollout on uninitialized http2 conn\n");
 265                 return 0;
 266         }
 267
 268         lwsl_info("%s: doing children\n", __func__);
 269
 270         wsi2 = wsi;
 271         do {
 272                 wsi2 = wsi2->u.http2.next_child_wsi;
 273                 lwsl_info("%s: child %p\n", __func__, wsi2);
 274                 if (!wsi2)
 275                         continue;
 276                 if (!wsi2->u.http2.requested_POLLOUT)
 277                         continue;
 278                 wsi2->u.http2.requested_POLLOUT = 0;
 279                 if (lws_calllback_as_writeable(wsi2)) {
 280                         lwsl_debug("Closing POLLOUT child\n");
 281                         lws_close_free_wsi(wsi2, LWS_CLOSE_STATUS_NOSTATUS);
 282                 }
 283                 wsi2 = wsi;
 284         } while (wsi2 != NULL && !lws_send_pipe_choked(wsi));
 285
 286         lwsl_info("%s: completed\n", __func__);
 287
 288         return 0;
 289 notify:
 290 #endif
 291         return lws_calllback_as_writeable(wsi);
 292 }
 293
 294 int
 295 lws_service_timeout_check(struct lws *wsi, unsigned int sec)
 296 {
 297         struct lws_context_per_thread *pt = &wsi->context->pt[(int)wsi->tsi];
 298
 299         /*
 300          * if extensions want in on it (eg, we are a mux parent)
 301          * give them a chance to service child timeouts
 302          */
 303         if (lws_ext_cb_active(wsi, LWS_EXT_CB_1HZ, NULL, sec) < 0)
 304                 return 0;
 305
 306         if (!wsi->pending_timeout)
 307                 return 0;
 308
 309         /*
 310          * if we went beyond the allowed time, kill the
 311          * connection
 312          */
 313         if ((time_t)sec > wsi->pending_timeout_limit) {
 314 #if LWS_POSIX
 315                 lwsl_notice("wsi %p: TIMEDOUT WAITING on %d (did hdr %d, ah %p, wl %d, pfd events %d)\n",
 316                             (void *)wsi, wsi->pending_timeout,
 317                             wsi->hdr_parsing_completed, wsi->u.hdr.ah,
 318                             pt->ah_wait_list_length,
 319                             pt->fds[wsi->sock].events);
 320 #endif
 321                 /*
 322                  * Since he failed a timeout, he already had a chance to do
 323                  * something and was unable to... that includes situations like
 324                  * half closed connections.  So process this "failed timeout"
 325                  * close as a violent death and don't try to do protocol
 326                  * cleanup like flush partials.
 327                  */
 328                 wsi->socket_is_permanently_unusable = 1;
 329                 lws_close_free_wsi(wsi, LWS_CLOSE_STATUS_NOSTATUS);
 330
 331                 return 1;
 332         }
 333
 334         return 0;
 335 }
 336
 337 int lws_rxflow_cache(struct lws *wsi, unsigned char *buf, int n, int len)
 338 {
 339         /* his RX is flowcontrolled, don't send remaining now */
 340         if (wsi->rxflow_buffer) {
 341                 /* rxflow while we were spilling prev rxflow */
 342                 lwsl_info("stalling in existing rxflow buf\n");
 343                 return 1;
 344         }
 345
 346         /* a new rxflow, buffer it and warn caller */
 347         lwsl_info("new rxflow input buffer len %d\n", len - n);
 348         wsi->rxflow_buffer = lws_malloc(len - n);
 349         wsi->rxflow_len = len - n;
 350         wsi->rxflow_pos = 0;
 351         memcpy(wsi->rxflow_buffer, buf + n, len - n);
 352
 353         return 0;
 354 }
 355
 356 /* this is used by the platform service code to stop us waiting for network
 357  * activity in poll() when we have something that already needs service
 358  */
 359
 360 int
 361 lws_service_adjust_timeout(struct lws_context *context, int timeout_ms, int tsi)
 362 {
 363         struct lws_context_per_thread *pt = &context->pt[tsi];
 364         int n;
 365
 366         /* Figure out if we really want to wait in poll()
 367          * We only need to wait if really nothing already to do and we have
 368          * to wait for something from network
 369          */
 370
 371         /* 1) if we know we are draining rx ext, do not wait in poll */
 372         if (pt->rx_draining_ext_list)
 373                 timeout_ms = 0;
 374
 375 #ifdef LWS_OPENSSL_SUPPORT
 376         /* 2) if we know we have non-network pending data, do not wait in poll */
 377         if (lws_ssl_anybody_has_buffered_read_tsi(context, tsi)) {
 378                 timeout_ms = 0;
 379                 lwsl_err("ssl buffered read\n");
 380         }
 381 #endif
 382
 383         /* 3) if any ah has pending rx, do not wait in poll */
 384         for (n = 0; n < context->max_http_header_pool; n++)
 385                 if (pt->ah_pool[n].rxpos != pt->ah_pool[n].rxlen) {
 386                         /* any ah with pending rx must be attached to someone */
 387                         assert(pt->ah_pool[n].wsi);
 388                         timeout_ms = 0;
 389                         break;
 390                 }
 391
 392         return timeout_ms;
 393 }
 394
 395 /*
 396  * guys that need POLLIN service again without waiting for network action
 397  * can force POLLIN here if not flowcontrolled, so they will get service.
 398  *
 399  * Return nonzero if anybody got their POLLIN faked
 400  */
 401 int
 402 lws_service_flag_pending(struct lws_context *context, int tsi)
 403 {
 404         struct lws_context_per_thread *pt = &context->pt[tsi];
 405 #ifdef LWS_OPENSSL_SUPPORT
 406         struct lws *wsi_next;
 407 #endif
 408         struct lws *wsi;
 409         int forced = 0;
 410         int n;
 411
 412         /* POLLIN faking */
 413
 414         /*
 415          * 1) For all guys with already-available ext data to drain, if they are
 416          * not flowcontrolled, fake their POLLIN status
 417          */
 418         wsi = pt->rx_draining_ext_list;
 419         while (wsi) {
 420                 pt->fds[wsi->position_in_fds_table].revents |=
 421                         pt->fds[wsi->position_in_fds_table].events & LWS_POLLIN;
 422                 if (pt->fds[wsi->position_in_fds_table].revents &
 423                     LWS_POLLIN)
 424                         forced = 1;
 425                 wsi = wsi->u.ws.rx_draining_ext_list;
 426         }
 427
 428 #ifdef LWS_OPENSSL_SUPPORT
 429         /*
 430          * 2) For all guys with buffered SSL read data already saved up, if they
 431          * are not flowcontrolled, fake their POLLIN status so they'll get
 432          * service to use up the buffered incoming data, even though their
 433          * network socket may have nothing
 434          */
 435         wsi = pt->pending_read_list;
 436         while (wsi) {
 437                 wsi_next = wsi->pending_read_list_next;
 438                 pt->fds[wsi->position_in_fds_table].revents |=
 439                         pt->fds[wsi->position_in_fds_table].events & LWS_POLLIN;
 440                 if (pt->fds[wsi->position_in_fds_table].revents & LWS_POLLIN) {
 441                         forced = 1;
 442                         /*
 443                          * he's going to get serviced now, take him off the
 444                          * list of guys with buffered SSL.  If he still has some
 445                          * at the end of the service, he'll get put back on the
 446                          * list then.
 447                          */
 448                         lws_ssl_remove_wsi_from_buffered_list(wsi);
 449                 }
 450
 451                 wsi = wsi_next;
 452         }
 453 #endif
 454         /*
 455          * 3) For any wsi who have an ah with pending RX who did not
 456          * complete their current headers, and are not flowcontrolled,
 457          * fake their POLLIN status so they will be able to drain the
 458          * rx buffered in the ah
 459          */
 460         for (n = 0; n < context->max_http_header_pool; n++)
 461                 if (pt->ah_pool[n].rxpos != pt->ah_pool[n].rxlen &&
 462                     !pt->ah_pool[n].wsi->hdr_parsing_completed) {
 463                         pt->fds[pt->ah_pool[n].wsi->position_in_fds_table].revents |=
 464                                 pt->fds[pt->ah_pool[n].wsi->position_in_fds_table].events &
 465                                         LWS_POLLIN;
 466                         if (pt->fds[pt->ah_pool[n].wsi->position_in_fds_table].revents &
 467                             LWS_POLLIN)
 468                                 forced = 1;
 469                 }
 470
 471         return forced;
 472 }
 473
 474 /**
 475  * lws_service_fd() - Service polled socket with something waiting
 476  * @context:    Websocket context
 477  * @pollfd:     The pollfd entry describing the socket fd and which events
 478  *              happened.
 479  *
 480  *      This function takes a pollfd that has POLLIN or POLLOUT activity and
 481  *      services it according to the state of the associated
 482  *      struct lws.
 483  *
 484  *      The one call deals with all "service" that might happen on a socket
 485  *      including listen accepts, http files as well as websocket protocol.
 486  *
 487  *      If a pollfd says it has something, you can just pass it to
 488  *      lws_service_fd() whether it is a socket handled by lws or not.
 489  *      If it sees it is a lws socket, the traffic will be handled and
 490  *      pollfd->revents will be zeroed now.
 491  *
 492  *      If the socket is foreign to lws, it leaves revents alone.  So you can
 493  *      see if you should service yourself by checking the pollfd revents
 494  *      after letting lws try to service it.
 495  */
 496
 497 LWS_VISIBLE int
 498 lws_service_fd_tsi(struct lws_context *context, struct lws_pollfd *pollfd, int tsi)
 499 {
 500         struct lws_context_per_thread *pt = &context->pt[tsi];
 501         lws_sockfd_type our_fd = 0, tmp_fd;
 502         struct lws_tokens eff_buf;
 503         unsigned int pending = 0;
 504         struct lws *wsi, *wsi1;
 505         char draining_flow = 0;
 506         int timed_out = 0;
 507         time_t now;
 508         int n = 0, m;
 509         int more;
 510
 511         /*
 512          * you can call us with pollfd = NULL to just allow the once-per-second
 513          * global timeout checks; if less than a second since the last check
 514          * it returns immediately then.
 515          */
 516
 517         time(&now);
 518
 519         /* TODO: if using libev, we should probably use timeout watchers... */
 520         if (context->last_timeout_check_s != now) {
 521                 context->last_timeout_check_s = now;
 522
 523                 lws_plat_service_periodic(context);
 524
 525                 /* global timeout check once per second */
 526
 527                 if (pollfd)
 528                         our_fd = pollfd->fd;
 529
 530                 wsi = context->pt[tsi].timeout_list;
 531                 while (wsi) {
 532                         /* we have to take copies, because he may be deleted */
 533                         wsi1 = wsi->timeout_list;
 534                         tmp_fd = wsi->sock;
 535                         if (lws_service_timeout_check(wsi, (unsigned int)now)) {
 536                                 /* he did time out... */
 537                                 if (tmp_fd == our_fd)
 538                                         /* it was the guy we came to service! */
 539                                         timed_out = 1;
 540                                         /* he's gone, no need to mark as handled */
 541                         }
 542                         wsi = wsi1;
 543                 }
 544 #ifdef LWS_WITH_CGI
 545                 lws_cgi_kill_terminated(pt);
 546 #endif
 547 #if 0
 548                 {
 549                         char s[300], *p = s;
 550
 551                         for (n = 0; n < context->count_threads; n++)
 552                                 p += sprintf(p, " %7lu (%5d), ",
 553                                              context->pt[n].count_conns,
 554                                              context->pt[n].fds_count);
 555
 556                         lwsl_notice("load: %s\n", s);
 557                 }
 558 #endif
 559         }
 560
 561         /* the socket we came to service timed out, nothing to do */
 562         if (timed_out)
 563                 return 0;
 564
 565         /* just here for timeout management? */
 566         if (!pollfd)
 567                 return 0;
 568
 569         /* no, here to service a socket descriptor */
 570         wsi = wsi_from_fd(context, pollfd->fd);
 571         if (!wsi)
 572                 /* not lws connection ... leave revents alone and return */
 573                 return 0;
 574
 575         /*
 576          * so that caller can tell we handled, past here we need to
 577          * zero down pollfd->revents after handling
 578          */
 579
 580 #if LWS_POSIX
 581         /* handle session socket closed */
 582
 583         if ((!(pollfd->revents & pollfd->events & LWS_POLLIN)) &&
 584             (pollfd->revents & LWS_POLLHUP)) {
 585                 wsi->socket_is_permanently_unusable = 1;
 586                 lwsl_debug("Session Socket %p (fd=%d) dead\n",
 587                                                        (void *)wsi, pollfd->fd);
 588
 589                 goto close_and_handled;
 590         }
 591
 592 #ifdef _WIN32
 593         if (pollfd->revents & LWS_POLLOUT)
 594                 wsi->sock_send_blocking = FALSE;
 595 #endif
 596
 597 #endif
 598
 599         lwsl_debug("fd=%d, revents=%d\n", pollfd->fd, pollfd->revents);
 600
 601         /* okay, what we came here to do... */
 602
 603         switch (wsi->mode) {
 604         case LWSCM_HTTP_SERVING:
 605         case LWSCM_HTTP_CLIENT:
 606         case LWSCM_HTTP_SERVING_ACCEPTED:
 607         case LWSCM_SERVER_LISTENER:
 608         case LWSCM_SSL_ACK_PENDING:
 609                 if (wsi->state == LWSS_CLIENT_HTTP_ESTABLISHED) {
 610                         goto handled;
 611                 }
 612                 n = lws_server_socket_service(context, wsi, pollfd);
 613                 if (n) /* closed by above */
 614                         return 1;
 615                 pending = lws_ssl_pending(wsi);
 616                 if (pending)
 617                         goto handle_pending;
 618                 goto handled;
 619
 620         case LWSCM_WS_SERVING:
 621         case LWSCM_WS_CLIENT:
 622         case LWSCM_HTTP2_SERVING:
 623         case LWSCM_HTTP_CLIENT_ACCEPTED:
 624
 625                 /* 1: something requested a callback when it was OK to write */
 626
 627                 if ((pollfd->revents & LWS_POLLOUT) &&
 628                     (wsi->state == LWSS_ESTABLISHED ||
 629                      wsi->state == LWSS_HTTP2_ESTABLISHED ||
 630                      wsi->state == LWSS_HTTP2_ESTABLISHED_PRE_SETTINGS ||
 631                      wsi->state == LWSS_RETURNED_CLOSE_ALREADY ||
 632                      wsi->state == LWSS_FLUSHING_STORED_SEND_BEFORE_CLOSE) &&
 633                     lws_handle_POLLOUT_event(wsi, pollfd)) {
 634                         if (wsi->state == LWSS_RETURNED_CLOSE_ALREADY)
 635                                 wsi->state = LWSS_FLUSHING_STORED_SEND_BEFORE_CLOSE;
 636                         lwsl_info("lws_service_fd: closing\n");
 637                         goto close_and_handled;
 638                 }
 639
 640                 if (wsi->state == LWSS_RETURNED_CLOSE_ALREADY ||
 641                     wsi->state == LWSS_AWAITING_CLOSE_ACK) {
 642                         /*
 643                          * we stopped caring about anything except control
 644                          * packets.  Force flow control off, defeat tx
 645                          * draining.
 646                          */
 647                         lws_rx_flow_control(wsi, 1);
 648                         wsi->u.ws.tx_draining_ext = 0;
 649                 }
 650
 651                 if (wsi->u.ws.tx_draining_ext)
 652                         /* we cannot deal with new RX until the TX ext
 653                          * path has been drained.  It's because new
 654                          * rx will, eg, crap on the wsi rx buf that
 655                          * may be needed to retain state.
 656                          *
 657                          * TX ext drain path MUST go through event loop
 658                          * to avoid blocking.
 659                          */
 660                         break;
 661
 662                 if (!(wsi->rxflow_change_to & LWS_RXFLOW_ALLOW))
 663                         /* We cannot deal with any kind of new RX
 664                          * because we are RX-flowcontrolled.
 665                          */
 666                         break;
 667
 668                 /* 2: RX Extension needs to be drained
 669                  */
 670
 671                 if (wsi->state == LWSS_ESTABLISHED &&
 672                     wsi->u.ws.rx_draining_ext) {
 673
 674                         lwsl_ext("%s: RX EXT DRAINING: Service\n", __func__);
 675 #ifndef LWS_NO_CLIENT
 676                         if (wsi->mode == LWSCM_WS_CLIENT) {
 677                                 n = lws_client_rx_sm(wsi, 0);
 678                                 if (n < 0)
 679                                         /* we closed wsi */
 680                                         n = 0;
 681                         } else
 682 #endif
 683                                 n = lws_rx_sm(wsi, 0);
 684
 685                         goto handled;
 686                 }
 687
 688                 if (wsi->u.ws.rx_draining_ext)
 689                         /*
 690                          * We have RX EXT content to drain, but can't do it
 691                          * right now.  That means we cannot do anything lower
 692                          * priority either.
 693                          */
 694                         break;
 695
 696                 /* 3: RX Flowcontrol buffer needs to be drained
 697                  */
 698
 699                 if (wsi->rxflow_buffer) {
 700                         lwsl_info("draining rxflow (len %d)\n",
 701                                 wsi->rxflow_len - wsi->rxflow_pos
 702                         );
 703                         /* well, drain it */
 704                         eff_buf.token = (char *)wsi->rxflow_buffer +
 705                                                 wsi->rxflow_pos;
 706                         eff_buf.token_len = wsi->rxflow_len - wsi->rxflow_pos;
 707                         draining_flow = 1;
 708                         goto drain;
 709                 }
 710
 711                 /* 4: any incoming (or ah-stashed incoming rx) data ready?
 712                  * notice if rx flow going off raced poll(), rx flow wins
 713                  */
 714
 715                 if (!(pollfd->revents & pollfd->events & LWS_POLLIN))
 716                         break;
 717 read:
 718
 719                 /* all the union members start with hdr, so even in ws mode
 720                  * we can deal with the ah via u.hdr
 721                  */
 722                 if (wsi->u.hdr.ah) {
 723                         lwsl_err("%s: %p: using inherited ah rx\n", __func__, wsi);
 724                         eff_buf.token_len = wsi->u.hdr.ah->rxlen -
 725                                             wsi->u.hdr.ah->rxpos;
 726                         eff_buf.token = (char *)wsi->u.hdr.ah->rx +
 727                                         wsi->u.hdr.ah->rxpos;
 728                 } else {
 729
 730                         eff_buf.token_len = lws_ssl_capable_read(wsi, pt->serv_buf,
 731                                              pending ? pending : LWS_MAX_SOCKET_IO_BUF);
 732                         switch (eff_buf.token_len) {
 733                         case 0:
 734                                 lwsl_info("service_fd: closing due to 0 length read\n");
 735                                 goto close_and_handled;
 736                         case LWS_SSL_CAPABLE_MORE_SERVICE:
 737                                 lwsl_info("SSL Capable more service\n");
 738                                 n = 0;
 739                                 goto handled;
 740                         case LWS_SSL_CAPABLE_ERROR:
 741                                 lwsl_info("Closing when error\n");
 742                                 goto close_and_handled;
 743                         }
 744
 745                         eff_buf.token = (char *)pt->serv_buf;
 746                 }
 747
 748                 /*
 749                  * give any active extensions a chance to munge the buffer
 750                  * before parse.  We pass in a pointer to an lws_tokens struct
 751                  * prepared with the default buffer and content length that's in
 752                  * there.  Rather than rewrite the default buffer, extensions
 753                  * that expect to grow the buffer can adapt .token to
 754                  * point to their own per-connection buffer in the extension
 755                  * user allocation.  By default with no extensions or no
 756                  * extension callback handling, just the normal input buffer is
 757                  * used then so it is efficient.
 758                  */
 759 drain:
 760                 if (wsi->mode == LWSCM_HTTP_CLIENT_ACCEPTED) {
 761                         lwsl_notice("%s: calling LWS_CALLBACK_RECEIVE_CLIENT_HTTP, "
 762                                     "rem %d len %d\n", __func__,
 763                                     wsi->u.http.content_remain, eff_buf.token_len);
 764                         if (wsi->u.http.content_remain < eff_buf.token_len)
 765                                 n = wsi->u.http.content_remain;
 766                         else
 767                                 n = eff_buf.token_len;
 768                         if (user_callback_handle_rxflow(wsi->protocol->callback,
 769                                         wsi, LWS_CALLBACK_RECEIVE_CLIENT_HTTP,
 770                                         wsi->user_space, (void *)eff_buf.token,
 771                                         eff_buf.token_len))
 772                                 goto close_and_handled;
 773                         wsi->u.http.content_remain -= n;
 774                         if (wsi->u.http.content_remain)
 775                                 goto handled;
 776
 777                         lwsl_notice("%s: client http receved all content\n",
 778                                     __func__);
 779                         if (user_callback_handle_rxflow(wsi->protocol->callback,
 780                                         wsi, LWS_CALLBACK_COMPLETED_CLIENT_HTTP,
 781                                         wsi->user_space, NULL, 0))
 782                                 goto close_and_handled;
 783
 784                         if (wsi->u.http.connection_type == HTTP_CONNECTION_CLOSE)
 785                                 goto close_and_handled;
 786                         goto handled;
 787                 }
 788                 do {
 789                         more = 0;
 790
 791                         m = lws_ext_cb_active(wsi, LWS_EXT_CB_PACKET_RX_PREPARSE,
 792                                               &eff_buf, 0);
 793                         if (m < 0)
 794                                 goto close_and_handled;
 795                         if (m)
 796                                 more = 1;
 797
 798                         /* service incoming data */
 799
 800                         if (eff_buf.token_len) {
 801                                 /*
 802                                  * if draining from rxflow buffer, not
 803                                  * critical to track what was used since at the
 804                                  * use it bumps wsi->rxflow_pos.  If we come
 805                                  * around again it will pick up from where it
 806                                  * left off.
 807                                  */
 808                                 n = lws_read(wsi, (unsigned char *)eff_buf.token,
 809                                              eff_buf.token_len);
 810                                 if (n < 0) {
 811                                         /* we closed wsi */
 812                                         n = 0;
 813                                         goto handled;
 814                                 }
 815                         }
 816
 817                         eff_buf.token = NULL;
 818                         eff_buf.token_len = 0;
 819                 } while (more);
 820
 821                 if (wsi->u.hdr.ah) {
 822                         lwsl_err("%s: %p: detaching inherited used ah\n",
 823                                  __func__, wsi);
 824                         /* show we used all the pending rx up */
 825                         wsi->u.hdr.ah->rxpos = wsi->u.hdr.ah->rxlen;
 826                         /* we can run the normal ah detach flow despite
 827                          * being in ws union mode, since all union members
 828                          * start with hdr */
 829                         lws_header_table_detach(wsi, 0);
 830                 }
 831
 832                 pending = lws_ssl_pending(wsi);
 833                 if (pending) {
 834 handle_pending:
 835                         pending = pending > LWS_MAX_SOCKET_IO_BUF ?
 836                                         LWS_MAX_SOCKET_IO_BUF : pending;
 837                         goto read;
 838                 }
 839
 840                 if (draining_flow && wsi->rxflow_buffer &&
 841                     wsi->rxflow_pos == wsi->rxflow_len) {
 842                         lwsl_info("flow buffer: drained\n");
 843                         lws_free_set_NULL(wsi->rxflow_buffer);
 844                         /* having drained the rxflow buffer, can rearm POLLIN */
 845 #ifdef LWS_NO_SERVER
 846                         n =
 847 #endif
 848                         _lws_rx_flow_control(wsi);
 849                         /* n ignored, needed for NO_SERVER case */
 850                 }
 851
 852                 break;
 853 #ifdef LWS_WITH_CGI
 854         case LWSCM_CGI: /* we exist to handle a cgi's stdin/out/err data...
 855                          * do the callback on our master wsi
 856                          */
 857                 {
 858                         struct lws_cgi_args args;
 859
 860                         if (wsi->cgi_channel >= LWS_STDOUT &&
 861                             !(pollfd->revents & pollfd->events & LWS_POLLIN))
 862                                 break;
 863                         if (wsi->cgi_channel == LWS_STDIN &&
 864                             !(pollfd->revents & pollfd->events & LWS_POLLOUT))
 865                                 break;
 866
 867                         if (wsi->cgi_channel == LWS_STDIN)
 868                                 if (lws_change_pollfd(wsi, LWS_POLLOUT, 0)) {
 869                                         lwsl_info("failed at set pollfd\n");
 870                                         return 1;
 871                                 }
 872
 873                         args.ch = wsi->cgi_channel;
 874                         args.stdwsi = &wsi->parent->cgi->stdwsi[0];
 875
 876                         if (user_callback_handle_rxflow(
 877                                         wsi->parent->protocol->callback,
 878                                         wsi->parent, LWS_CALLBACK_CGI,
 879                                         wsi->parent->user_space,
 880                                         (void *)&args, 0))
 881                                 return 1;
 882
 883                         break;
 884                 }
 885 #endif
 886         default:
 887 #ifdef LWS_NO_CLIENT
 888                 break;
 889 #else
 890                 n = lws_client_socket_service(context, wsi, pollfd);
 891                 if (n)
 892                         return 1;
 893                 goto handled;
 894 #endif
 895         }
 896
 897         n = 0;
 898         goto handled;
 899
 900 close_and_handled:
 901         lwsl_debug("Close and handled\n");
 902         lws_close_free_wsi(wsi, LWS_CLOSE_STATUS_NOSTATUS);
 903         /*
 904          * pollfd may point to something else after the close
 905          * due to pollfd swapping scheme on delete on some platforms
 906          * we can't clear revents now because it'd be the wrong guy's revents
 907          */
 908         return 1;
 909
 910 handled:
 911         pollfd->revents = 0;
 912         return n;
 913 }
 914
 915 LWS_VISIBLE int
 916 lws_service_fd(struct lws_context *context, struct lws_pollfd *pollfd)
 917 {
 918         return lws_service_fd_tsi(context, pollfd, 0);
 919 }
 920
 921 /**
 922  * lws_service() - Service any pending websocket activity
 923  * @context:    Websocket context
 924  * @timeout_ms: Timeout for poll; 0 means return immediately if nothing needed
 925  *              service otherwise block and service immediately, returning
 926  *              after the timeout if nothing needed service.
 927  *
 928  *      This function deals with any pending websocket traffic, for three
 929  *      kinds of event.  It handles these events on both server and client
 930  *      types of connection the same.
 931  *
 932  *      1) Accept new connections to our context's server
 933  *
 934  *      2) Call the receive callback for incoming frame data received by
 935  *          server or client connections.
 936  *
 937  *      You need to call this service function periodically to all the above
 938  *      functions to happen; if your application is single-threaded you can
 939  *      just call it in your main event loop.
 940  *
 941  *      Alternatively you can fork a new process that asynchronously handles
 942  *      calling this service in a loop.  In that case you are happy if this
 943  *      call blocks your thread until it needs to take care of something and
 944  *      would call it with a large nonzero timeout.  Your loop then takes no
 945  *      CPU while there is nothing happening.
 946  *
 947  *      If you are calling it in a single-threaded app, you don't want it to
 948  *      wait around blocking other things in your loop from happening, so you
 949  *      would call it with a timeout_ms of 0, so it returns immediately if
 950  *      nothing is pending, or as soon as it services whatever was pending.
 951  */
 952
 953 LWS_VISIBLE int
 954 lws_service(struct lws_context *context, int timeout_ms)
 955 {
 956         return lws_plat_service(context, timeout_ms);
 957 }
 958
 959 LWS_VISIBLE int
 960 lws_service_tsi(struct lws_context *context, int timeout_ms, int tsi)
 961 {
 962         return lws_plat_service_tsi(context, timeout_ms, tsi);
 963 }
 964