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 #ifdef LWS_USE_HTTP2
 241         /*
 242          * we are the 'network wsi' for potentially many muxed child wsi with
 243          * no network connection of their own, who have to use us for all their
 244          * network actions.  So we use a round-robin scheme to share out the
 245          * POLLOUT notifications to our children.
 246          *
 247          * But because any child could exhaust the socket's ability to take
 248          * writes, we can only let one child get notified each time.
 249          *
 250          * In addition children may be closed / deleted / added between POLLOUT
 251          * notifications, so we can't hold pointers
 252          */
 253
 254         if (wsi->mode != LWSCM_HTTP2_SERVING) {
 255                 lwsl_info("%s: non http2\n", __func__);
 256                 goto notify;
 257         }
 258
 259         wsi->u.http2.requested_POLLOUT = 0;
 260         if (!wsi->u.http2.initialized) {
 261                 lwsl_info("pollout on uninitialized http2 conn\n");
 262                 return 0;
 263         }
 264
 265         lwsl_info("%s: doing children\n", __func__);
 266
 267         wsi2 = wsi;
 268         do {
 269                 wsi2 = wsi2->u.http2.next_child_wsi;
 270                 lwsl_info("%s: child %p\n", __func__, wsi2);
 271                 if (!wsi2)
 272                         continue;
 273                 if (!wsi2->u.http2.requested_POLLOUT)
 274                         continue;
 275                 wsi2->u.http2.requested_POLLOUT = 0;
 276                 if (lws_calllback_as_writeable(wsi2)) {
 277                         lwsl_debug("Closing POLLOUT child\n");
 278                         lws_close_free_wsi(wsi2, LWS_CLOSE_STATUS_NOSTATUS);
 279                 }
 280                 wsi2 = wsi;
 281         } while (wsi2 != NULL && !lws_send_pipe_choked(wsi));
 282
 283         lwsl_info("%s: completed\n", __func__);
 284
 285         return 0;
 286 notify:
 287 #endif
 288         return lws_calllback_as_writeable(wsi);
 289 }
 290
 291 int
 292 lws_service_timeout_check(struct lws *wsi, unsigned int sec)
 293 {
 294         struct lws_context_per_thread *pt = &wsi->context->pt[(int)wsi->tsi];
 295         struct lws **pwsi;
 296
 297         /*
 298          * if extensions want in on it (eg, we are a mux parent)
 299          * give them a chance to service child timeouts
 300          */
 301         if (lws_ext_cb_active(wsi, LWS_EXT_CB_1HZ, NULL, sec) < 0)
 302                 return 0;
 303
 304         if (!wsi->pending_timeout)
 305                 return 0;
 306
 307         /*
 308          * if we went beyond the allowed time, kill the
 309          * connection
 310          */
 311         if ((time_t)sec > wsi->pending_timeout_limit) {
 312 #if LWS_POSIX
 313                 lwsl_notice("wsi %p: TIMEDOUT WAITING on %d (did hdr %d, ah %p, wl %d, pfd events %d)\n",
 314                             (void *)wsi, wsi->pending_timeout,
 315                             wsi->hdr_parsing_completed, wsi->u.hdr.ah,
 316                             pt->ah_wait_list_length,
 317                             pt->fds[wsi->sock].events);
 318 #endif
 319                 lws_pt_lock(pt);
 320
 321                 pwsi = &pt->ah_wait_list;
 322                 if (!pwsi)
 323                         return 0;
 324                 while (*pwsi) {
 325                         if (*pwsi == wsi)
 326                                 break;
 327                         pwsi = &(*pwsi)->u.hdr.ah_wait_list;
 328                         lwsl_err("%s: pwsi=%p\n", __func__, pwsi);
 329                 }
 330                 lws_pt_unlock(pt);
 331
 332                 if (!*pwsi)
 333                         lwsl_err("*** not on ah wait list ***\n");
 334                 /*
 335                  * Since he failed a timeout, he already had a chance to do
 336                  * something and was unable to... that includes situations like
 337                  * half closed connections.  So process this "failed timeout"
 338                  * close as a violent death and don't try to do protocol
 339                  * cleanup like flush partials.
 340                  */
 341                 wsi->socket_is_permanently_unusable = 1;
 342                 lws_close_free_wsi(wsi, LWS_CLOSE_STATUS_NOSTATUS);
 343
 344                 return 1;
 345         }
 346
 347         return 0;
 348 }
 349
 350 int lws_rxflow_cache(struct lws *wsi, unsigned char *buf, int n, int len)
 351 {
 352         /* his RX is flowcontrolled, don't send remaining now */
 353         if (wsi->rxflow_buffer) {
 354                 /* rxflow while we were spilling prev rxflow */
 355                 lwsl_info("stalling in existing rxflow buf\n");
 356                 return 1;
 357         }
 358
 359         /* a new rxflow, buffer it and warn caller */
 360         lwsl_info("new rxflow input buffer len %d\n", len - n);
 361         wsi->rxflow_buffer = lws_malloc(len - n);
 362         wsi->rxflow_len = len - n;
 363         wsi->rxflow_pos = 0;
 364         memcpy(wsi->rxflow_buffer, buf + n, len - n);
 365
 366         return 0;
 367 }
 368
 369 /* this is used by the platform service code to stop us waiting for network
 370  * activity in poll() when we have something that already needs service
 371  */
 372
 373 int
 374 lws_service_adjust_timeout(struct lws_context *context, int timeout_ms, int tsi)
 375 {
 376         struct lws_context_per_thread *pt = &context->pt[tsi];
 377         int n;
 378
 379         /* Figure out if we really want to wait in poll()
 380          * We only need to wait if really nothing already to do and we have
 381          * to wait for something from network
 382          */
 383
 384         /* 1) if we know we are draining rx ext, do not wait in poll */
 385         if (pt->rx_draining_ext_list)
 386                 timeout_ms = 0;
 387
 388 #ifdef LWS_OPENSSL_SUPPORT
 389         /* 2) if we know we have non-network pending data, do not wait in poll */
 390         if (lws_ssl_anybody_has_buffered_read_tsi(context, tsi)) {
 391                 timeout_ms = 0;
 392                 lwsl_err("ssl buffered read\n");
 393         }
 394 #endif
 395
 396         /* 3) if any ah has pending rx, do not wait in poll */
 397         for (n = 0; n < context->max_http_header_pool; n++)
 398                 if (pt->ah_pool[n].rxpos != pt->ah_pool[n].rxlen) {
 399                         /* any ah with pending rx must be attached to someone */
 400                         assert(pt->ah_pool[n].wsi);
 401                         timeout_ms = 0;
 402                         break;
 403                 }
 404
 405         return timeout_ms;
 406 }
 407
 408 /*
 409  * guys that need POLLIN service again without waiting for network action
 410  * can force POLLIN here if not flowcontrolled, so they will get service.
 411  *
 412  * Return nonzero if anybody got their POLLIN faked
 413  */
 414 int
 415 lws_service_flag_pending(struct lws_context *context, int tsi)
 416 {
 417         struct lws_context_per_thread *pt = &context->pt[tsi];
 418 #ifdef LWS_OPENSSL_SUPPORT
 419         struct lws *wsi_next;
 420 #endif
 421         struct lws *wsi;
 422         int forced = 0;
 423         int n;
 424
 425         /* POLLIN faking */
 426
 427         /*
 428          * 1) For all guys with already-available ext data to drain, if they are
 429          * not flowcontrolled, fake their POLLIN status
 430          */
 431         wsi = pt->rx_draining_ext_list;
 432         while (wsi) {
 433                 pt->fds[wsi->position_in_fds_table].revents |=
 434                         pt->fds[wsi->position_in_fds_table].events & LWS_POLLIN;
 435                 if (pt->fds[wsi->position_in_fds_table].revents &
 436                     LWS_POLLIN)
 437                         forced = 1;
 438                 wsi = wsi->u.ws.rx_draining_ext_list;
 439         }
 440
 441 #ifdef LWS_OPENSSL_SUPPORT
 442         /*
 443          * 2) For all guys with buffered SSL read data already saved up, if they
 444          * are not flowcontrolled, fake their POLLIN status so they'll get
 445          * service to use up the buffered incoming data, even though their
 446          * network socket may have nothing
 447          */
 448         wsi = pt->pending_read_list;
 449         while (wsi) {
 450                 wsi_next = wsi->pending_read_list_next;
 451                 pt->fds[wsi->position_in_fds_table].revents |=
 452                         pt->fds[wsi->position_in_fds_table].events & LWS_POLLIN;
 453                 if (pt->fds[wsi->position_in_fds_table].revents & LWS_POLLIN) {
 454                         forced = 1;
 455                         /*
 456                          * he's going to get serviced now, take him off the
 457                          * list of guys with buffered SSL.  If he still has some
 458                          * at the end of the service, he'll get put back on the
 459                          * list then.
 460                          */
 461                         lws_ssl_remove_wsi_from_buffered_list(wsi);
 462                 }
 463
 464                 wsi = wsi_next;
 465         }
 466 #endif
 467         /*
 468          * 3) For any wsi who have an ah with pending RX who did not
 469          * complete their current headers, and are not flowcontrolled,
 470          * fake their POLLIN status so they will be able to drain the
 471          * rx buffered in the ah
 472          */
 473         for (n = 0; n < context->max_http_header_pool; n++)
 474                 if (pt->ah_pool[n].rxpos != pt->ah_pool[n].rxlen &&
 475                     !pt->ah_pool[n].wsi->hdr_parsing_completed) {
 476                         pt->fds[pt->ah_pool[n].wsi->position_in_fds_table].revents |=
 477                                 pt->fds[pt->ah_pool[n].wsi->position_in_fds_table].events &
 478                                         LWS_POLLIN;
 479                         if (pt->fds[pt->ah_pool[n].wsi->position_in_fds_table].revents &
 480                             LWS_POLLIN)
 481                                 forced = 1;
 482                 }
 483
 484         return forced;
 485 }
 486
 487 /**
 488  * lws_service_fd() - Service polled socket with something waiting
 489  * @context:    Websocket context
 490  * @pollfd:     The pollfd entry describing the socket fd and which events
 491  *              happened.
 492  *
 493  *      This function takes a pollfd that has POLLIN or POLLOUT activity and
 494  *      services it according to the state of the associated
 495  *      struct lws.
 496  *
 497  *      The one call deals with all "service" that might happen on a socket
 498  *      including listen accepts, http files as well as websocket protocol.
 499  *
 500  *      If a pollfd says it has something, you can just pass it to
 501  *      lws_service_fd() whether it is a socket handled by lws or not.
 502  *      If it sees it is a lws socket, the traffic will be handled and
 503  *      pollfd->revents will be zeroed now.
 504  *
 505  *      If the socket is foreign to lws, it leaves revents alone.  So you can
 506  *      see if you should service yourself by checking the pollfd revents
 507  *      after letting lws try to service it.
 508  */
 509
 510 LWS_VISIBLE int
 511 lws_service_fd_tsi(struct lws_context *context, struct lws_pollfd *pollfd, int tsi)
 512 {
 513         struct lws_context_per_thread *pt = &context->pt[tsi];
 514         lws_sockfd_type our_fd = 0, tmp_fd;
 515         struct lws_tokens eff_buf;
 516         unsigned int pending = 0;
 517         struct lws *wsi, *wsi1;
 518         char draining_flow = 0;
 519         int timed_out = 0;
 520         time_t now;
 521         int n, m;
 522         int more;
 523
 524         /*
 525          * you can call us with pollfd = NULL to just allow the once-per-second
 526          * global timeout checks; if less than a second since the last check
 527          * it returns immediately then.
 528          */
 529
 530         time(&now);
 531
 532         /* TODO: if using libev, we should probably use timeout watchers... */
 533         if (context->last_timeout_check_s != now) {
 534                 context->last_timeout_check_s = now;
 535
 536                 lws_plat_service_periodic(context);
 537
 538                 /* global timeout check once per second */
 539
 540                 if (pollfd)
 541                         our_fd = pollfd->fd;
 542
 543                 wsi = context->pt[tsi].timeout_list;
 544                 while (wsi) {
 545                         /* we have to take copies, because he may be deleted */
 546                         wsi1 = wsi->timeout_list;
 547                         tmp_fd = wsi->sock;
 548                         if (lws_service_timeout_check(wsi, (unsigned int)now)) {
 549                                 /* he did time out... */
 550                                 if (tmp_fd == our_fd)
 551                                         /* it was the guy we came to service! */
 552                                         timed_out = 1;
 553                                         /* he's gone, no need to mark as handled */
 554                         }
 555                         wsi = wsi1;
 556                 }
 557 #if 0
 558                 {
 559                         char s[300], *p = s;
 560
 561                         for (n = 0; n < context->count_threads; n++)
 562                                 p += sprintf(p, " %7lu (%5d), ",
 563                                              context->pt[n].count_conns,
 564                                              context->pt[n].fds_count);
 565
 566                         lwsl_notice("load: %s\n", s);
 567                 }
 568 #endif
 569         }
 570
 571         /* the socket we came to service timed out, nothing to do */
 572         if (timed_out)
 573                 return 0;
 574
 575         /* just here for timeout management? */
 576         if (!pollfd)
 577                 return 0;
 578
 579         /* no, here to service a socket descriptor */
 580         wsi = wsi_from_fd(context, pollfd->fd);
 581         if (!wsi)
 582                 /* not lws connection ... leave revents alone and return */
 583                 return 0;
 584
 585         /*
 586          * so that caller can tell we handled, past here we need to
 587          * zero down pollfd->revents after handling
 588          */
 589
 590 #if LWS_POSIX
 591
 592         /* handle session socket closed */
 593
 594         if ((!(pollfd->revents & pollfd->events & LWS_POLLIN)) &&
 595             (pollfd->revents & LWS_POLLHUP)) {
 596                 wsi->socket_is_permanently_unusable = 1;
 597                 lwsl_debug("Session Socket %p (fd=%d) dead\n",
 598                                                        (void *)wsi, pollfd->fd);
 599
 600                 goto close_and_handled;
 601         }
 602
 603 #ifdef _WIN32
 604         if (pollfd->revents & LWS_POLLOUT)
 605                 wsi->sock_send_blocking = FALSE;
 606 #endif
 607
 608 #endif
 609
 610         /* okay, what we came here to do... */
 611
 612         switch (wsi->mode) {
 613         case LWSCM_HTTP_SERVING:
 614         case LWSCM_HTTP_SERVING_ACCEPTED:
 615         case LWSCM_SERVER_LISTENER:
 616         case LWSCM_SSL_ACK_PENDING:
 617                 n = lws_server_socket_service(context, wsi, pollfd);
 618                 if (n) /* closed by above */
 619                         return 1;
 620                 pending = lws_ssl_pending(wsi);
 621                 if (pending)
 622                         goto handle_pending;
 623                 goto handled;
 624
 625         case LWSCM_WS_SERVING:
 626         case LWSCM_WS_CLIENT:
 627         case LWSCM_HTTP2_SERVING:
 628
 629                 /* 1: something requested a callback when it was OK to write */
 630
 631                 if ((pollfd->revents & LWS_POLLOUT) &&
 632                     (wsi->state == LWSS_ESTABLISHED ||
 633                      wsi->state == LWSS_HTTP2_ESTABLISHED ||
 634                      wsi->state == LWSS_HTTP2_ESTABLISHED_PRE_SETTINGS ||
 635                      wsi->state == LWSS_RETURNED_CLOSE_ALREADY ||
 636                      wsi->state == LWSS_FLUSHING_STORED_SEND_BEFORE_CLOSE) &&
 637                     lws_handle_POLLOUT_event(wsi, pollfd)) {
 638                         if (wsi->state == LWSS_RETURNED_CLOSE_ALREADY)
 639                                 wsi->state = LWSS_FLUSHING_STORED_SEND_BEFORE_CLOSE;
 640                         lwsl_info("lws_service_fd: closing\n");
 641                         goto close_and_handled;
 642                 }
 643
 644                 if (wsi->state == LWSS_RETURNED_CLOSE_ALREADY ||
 645                     wsi->state == LWSS_AWAITING_CLOSE_ACK) {
 646                         /*
 647                          * we stopped caring about anything except control
 648                          * packets.  Force flow control off, defeat tx
 649                          * draining.
 650                          */
 651                         lws_rx_flow_control(wsi, 1);
 652                         wsi->u.ws.tx_draining_ext = 0;
 653                 }
 654
 655                 if (wsi->u.ws.tx_draining_ext) {
 656                         /* we cannot deal with new RX until the TX ext
 657                          * path has been drained.  It's because new
 658                          * rx will, eg, crap on the wsi rx buf that
 659                          * may be needed to retain state.
 660                          *
 661                          * TX ext drain path MUST go through event loop
 662                          * to avoid blocking.
 663                          */
 664                         break;
 665                 }
 666
 667                 if (!(wsi->rxflow_change_to & LWS_RXFLOW_ALLOW))
 668                         /* We cannot deal with any kind of new RX
 669                          * because we are RX-flowcontrolled.
 670                          */
 671                         break;
 672
 673                 /* 2: RX Extension needs to be drained
 674                  */
 675
 676                 if (wsi->state == LWSS_ESTABLISHED &&
 677                     wsi->u.ws.rx_draining_ext) {
 678
 679                         lwsl_ext("%s: RX EXT DRAINING: Service\n", __func__);
 680 #ifndef LWS_NO_CLIENT
 681                         if (wsi->mode == LWSCM_WS_CLIENT) {
 682                                 n = lws_client_rx_sm(wsi, 0);
 683                                 if (n < 0)
 684                                         /* we closed wsi */
 685                                         n = 0;
 686                         } else
 687 #endif
 688                                 n = lws_rx_sm(wsi, 0);
 689
 690                         goto handled;
 691                 }
 692
 693                 if (wsi->u.ws.rx_draining_ext)
 694                         /*
 695                          * We have RX EXT content to drain, but can't do it
 696                          * right now.  That means we cannot do anything lower
 697                          * priority either.
 698                          */
 699                         break;
 700
 701                 /* 3: RX Flowcontrol buffer needs to be drained
 702                  */
 703
 704                 if (wsi->rxflow_buffer) {
 705                         lwsl_info("draining rxflow (len %d)\n",
 706                                 wsi->rxflow_len - wsi->rxflow_pos
 707                         );
 708                         /* well, drain it */
 709                         eff_buf.token = (char *)wsi->rxflow_buffer +
 710                                                 wsi->rxflow_pos;
 711                         eff_buf.token_len = wsi->rxflow_len - wsi->rxflow_pos;
 712                         draining_flow = 1;
 713                         goto drain;
 714                 }
 715
 716                 /* 4: any incoming (or ah-stashed incoming rx) data ready?
 717                  * notice if rx flow going off raced poll(), rx flow wins
 718                  */
 719
 720                 if (!(pollfd->revents & pollfd->events & LWS_POLLIN))
 721                         break;
 722 read:
 723
 724                 /* all the union members start with hdr, so even in ws mode
 725                  * we can deal with the ah via u.hdr
 726                  */
 727                 if (wsi->u.hdr.ah) {
 728                         lwsl_err("%s: %p: using inherited ah rx\n", __func__, wsi);
 729                         eff_buf.token_len = wsi->u.hdr.ah->rxlen -
 730                                             wsi->u.hdr.ah->rxpos;
 731                         eff_buf.token = (char *)wsi->u.hdr.ah->rx +
 732                                         wsi->u.hdr.ah->rxpos;
 733                 } else {
 734
 735                         eff_buf.token_len = lws_ssl_capable_read(wsi, pt->serv_buf,
 736                                              pending ? pending : LWS_MAX_SOCKET_IO_BUF);
 737                         switch (eff_buf.token_len) {
 738                         case 0:
 739                                 lwsl_info("service_fd: closing due to 0 length read\n");
 740                                 goto close_and_handled;
 741                         case LWS_SSL_CAPABLE_MORE_SERVICE:
 742                                 lwsl_info("SSL Capable more service\n");
 743                                 n = 0;
 744                                 goto handled;
 745                         case LWS_SSL_CAPABLE_ERROR:
 746                                 lwsl_info("Closing when error\n");
 747                                 goto close_and_handled;
 748                         }
 749
 750                         eff_buf.token = (char *)pt->serv_buf;
 751                 }
 752                 /*
 753                  * give any active extensions a chance to munge the buffer
 754                  * before parse.  We pass in a pointer to an lws_tokens struct
 755                  * prepared with the default buffer and content length that's in
 756                  * there.  Rather than rewrite the default buffer, extensions
 757                  * that expect to grow the buffer can adapt .token to
 758                  * point to their own per-connection buffer in the extension
 759                  * user allocation.  By default with no extensions or no
 760                  * extension callback handling, just the normal input buffer is
 761                  * used then so it is efficient.
 762                  */
 763 drain:
 764                 do {
 765                         more = 0;
 766
 767                         m = lws_ext_cb_active(wsi, LWS_EXT_CB_PACKET_RX_PREPARSE,
 768                                               &eff_buf, 0);
 769                         if (m < 0)
 770                                 goto close_and_handled;
 771                         if (m)
 772                                 more = 1;
 773
 774                         /* service incoming data */
 775
 776                         if (eff_buf.token_len) {
 777                                 /*
 778                                  * if draining from rxflow buffer, not
 779                                  * critical to track what was used since at the
 780                                  * use it bumps wsi->rxflow_pos.  If we come
 781                                  * around again it will pick up from where it
 782                                  * left off.
 783                                  */
 784                                 n = lws_read(wsi, (unsigned char *)eff_buf.token,
 785                                              eff_buf.token_len);
 786                                 if (n < 0) {
 787                                         /* we closed wsi */
 788                                         n = 0;
 789                                         goto handled;
 790                                 }
 791                         }
 792
 793                         eff_buf.token = NULL;
 794                         eff_buf.token_len = 0;
 795                 } while (more);
 796
 797                 if (wsi->u.hdr.ah) {
 798                         lwsl_err("%s: %p: detaching inherited used ah\n", __func__, wsi);
 799                         /* show we used all the pending rx up */
 800                         wsi->u.hdr.ah->rxpos = wsi->u.hdr.ah->rxlen;
 801                         /* we can run the normal ah detach flow despite
 802                          * being in ws union mode, since all union members
 803                          * start with hdr */
 804                         lws_header_table_detach(wsi);
 805                 }
 806
 807                 pending = lws_ssl_pending(wsi);
 808                 if (pending) {
 809 handle_pending:
 810                         pending = pending > LWS_MAX_SOCKET_IO_BUF ?
 811                                         LWS_MAX_SOCKET_IO_BUF : pending;
 812                         goto read;
 813                 }
 814
 815                 if (draining_flow && wsi->rxflow_buffer &&
 816                     wsi->rxflow_pos == wsi->rxflow_len) {
 817                         lwsl_info("flow buffer: drained\n");
 818                         lws_free_set_NULL(wsi->rxflow_buffer);
 819                         /* having drained the rxflow buffer, can rearm POLLIN */
 820 #ifdef LWS_NO_SERVER
 821                         n =
 822 #endif
 823                         _lws_rx_flow_control(wsi);
 824                         /* n ignored, needed for NO_SERVER case */
 825                 }
 826
 827                 break;
 828
 829         default:
 830 #ifdef LWS_NO_CLIENT
 831                 break;
 832 #else
 833                 n = lws_client_socket_service(context, wsi, pollfd);
 834                 if (n)
 835                         return 1;
 836                 goto handled;
 837 #endif
 838         }
 839
 840         n = 0;
 841         goto handled;
 842
 843 close_and_handled:
 844         lwsl_debug("Close and handled\n");
 845         lws_close_free_wsi(wsi, LWS_CLOSE_STATUS_NOSTATUS);
 846         /*
 847          * pollfd may point to something else after the close
 848          * due to pollfd swapping scheme on delete on some platforms
 849          * we can't clear revents now because it'd be the wrong guy's revents
 850          */
 851         return 1;
 852
 853 handled:
 854         pollfd->revents = 0;
 855         return n;
 856 }
 857
 858 LWS_VISIBLE int
 859 lws_service_fd(struct lws_context *context, struct lws_pollfd *pollfd)
 860 {
 861         return lws_service_fd_tsi(context, pollfd, 0);
 862 }
 863
 864 /**
 865  * lws_service() - Service any pending websocket activity
 866  * @context:    Websocket context
 867  * @timeout_ms: Timeout for poll; 0 means return immediately if nothing needed
 868  *              service otherwise block and service immediately, returning
 869  *              after the timeout if nothing needed service.
 870  *
 871  *      This function deals with any pending websocket traffic, for three
 872  *      kinds of event.  It handles these events on both server and client
 873  *      types of connection the same.
 874  *
 875  *      1) Accept new connections to our context's server
 876  *
 877  *      2) Call the receive callback for incoming frame data received by
 878  *          server or client connections.
 879  *
 880  *      You need to call this service function periodically to all the above
 881  *      functions to happen; if your application is single-threaded you can
 882  *      just call it in your main event loop.
 883  *
 884  *      Alternatively you can fork a new process that asynchronously handles
 885  *      calling this service in a loop.  In that case you are happy if this
 886  *      call blocks your thread until it needs to take care of something and
 887  *      would call it with a large nonzero timeout.  Your loop then takes no
 888  *      CPU while there is nothing happening.
 889  *
 890  *      If you are calling it in a single-threaded app, you don't want it to
 891  *      wait around blocking other things in your loop from happening, so you
 892  *      would call it with a timeout_ms of 0, so it returns immediately if
 893  *      nothing is pending, or as soon as it services whatever was pending.
 894  */
 895
 896 LWS_VISIBLE int
 897 lws_service(struct lws_context *context, int timeout_ms)
 898 {
 899         return lws_plat_service(context, timeout_ms);
 900 }
 901
 902 LWS_VISIBLE int
 903 lws_service_tsi(struct lws_context *context, int timeout_ms, int tsi)
 904 {
 905         return lws_plat_service_tsi(context, timeout_ms, tsi);
 906 }
 907