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         //lwsl_err("%s: %p\n", __func__, wsi);
  57
  58         /*
  59          * user callback is lowest priority to get these notifications
  60          * actually, since other pending things cannot be disordered
  61          */
  62
  63         /* Priority 1: pending truncated sends are incomplete ws fragments
  64          *             If anything else sent first the protocol would be
  65          *             corrupted.
  66          */
  67         if (wsi->trunc_len) {
  68                 if (lws_issue_raw(wsi, wsi->trunc_alloc + wsi->trunc_offset,
  69                                   wsi->trunc_len) < 0) {
  70                         lwsl_info("%s signalling to close\n", __func__);
  71                         return -1;
  72                 }
  73                 /* leave POLLOUT active either way */
  74                 return 0;
  75         } else
  76                 if (wsi->state == LWSS_FLUSHING_STORED_SEND_BEFORE_CLOSE)
  77                         return -1; /* retry closing now */
  78
  79
  80 #ifdef LWS_USE_HTTP2
  81         /* Priority 2: protocol packets
  82          */
  83         if (wsi->pps) {
  84                 lwsl_info("servicing pps %d\n", wsi->pps);
  85                 switch (wsi->pps) {
  86                 case LWS_PPS_HTTP2_MY_SETTINGS:
  87                 case LWS_PPS_HTTP2_ACK_SETTINGS:
  88                         lws_http2_do_pps_send(lws_get_context(wsi), wsi);
  89                         break;
  90                 default:
  91                         break;
  92                 }
  93                 wsi->pps = LWS_PPS_NONE;
  94                 lws_rx_flow_control(wsi, 1);
  95
  96                 return 0; /* leave POLLOUT active */
  97         }
  98 #endif
  99
 100 #ifdef LWS_WITH_CGI
 101         if (wsi->cgi)
 102                 goto user_service_go_again;
 103 #endif
 104
 105         /* Priority 3: pending control packets (pong or close)
 106          */
 107         if ((wsi->state == LWSS_ESTABLISHED &&
 108              wsi->u.ws.ping_pending_flag) ||
 109             (wsi->state == LWSS_RETURNED_CLOSE_ALREADY &&
 110              wsi->u.ws.payload_is_close)) {
 111
 112                 if (wsi->u.ws.payload_is_close)
 113                         write_type = LWS_WRITE_CLOSE;
 114
 115                 n = lws_write(wsi, &wsi->u.ws.ping_payload_buf[LWS_PRE],
 116                               wsi->u.ws.ping_payload_len, write_type);
 117                 if (n < 0)
 118                         return -1;
 119
 120                 /* well he is sent, mark him done */
 121                 wsi->u.ws.ping_pending_flag = 0;
 122                 if (wsi->u.ws.payload_is_close)
 123                         /* oh... a close frame was it... then we are done */
 124                         return -1;
 125
 126                 /* otherwise for PING, leave POLLOUT active either way */
 127                 return 0;
 128         }
 129
 130         /* Priority 4: if we are closing, not allowed to send more data frags
 131          *             which means user callback or tx ext flush banned now
 132          */
 133         if (wsi->state == LWSS_RETURNED_CLOSE_ALREADY)
 134                 goto user_service;
 135
 136         /* Priority 5: Tx path extension with more to send
 137          *
 138          *             These are handled as new fragments each time around
 139          *             So while we must block new writeable callback to enforce
 140          *             payload ordering, but since they are always complete
 141          *             fragments control packets can interleave OK.
 142          */
 143         if (wsi->state == LWSS_ESTABLISHED && wsi->u.ws.tx_draining_ext) {
 144                 lwsl_ext("SERVICING TX EXT DRAINING\n");
 145                 if (lws_write(wsi, NULL, 0, LWS_WRITE_CONTINUATION) < 0)
 146                         return -1;
 147                 /* leave POLLOUT active */
 148                 return 0;
 149         }
 150
 151         /* Priority 6: user can get the callback
 152          */
 153         m = lws_ext_cb_active(wsi, LWS_EXT_CB_IS_WRITEABLE, NULL, 0);
 154         if (m)
 155                 return -1;
 156 #ifndef LWS_NO_EXTENSIONS
 157         if (!wsi->extension_data_pending)
 158                 goto user_service;
 159 #endif
 160         /*
 161          * check in on the active extensions, see if they
 162          * had pending stuff to spill... they need to get the
 163          * first look-in otherwise sequence will be disordered
 164          *
 165          * NULL, zero-length eff_buf means just spill pending
 166          */
 167
 168         ret = 1;
 169         while (ret == 1) {
 170
 171                 /* default to nobody has more to spill */
 172
 173                 ret = 0;
 174                 eff_buf.token = NULL;
 175                 eff_buf.token_len = 0;
 176
 177                 /* give every extension a chance to spill */
 178
 179                 m = lws_ext_cb_active(wsi,
 180                                         LWS_EXT_CB_PACKET_TX_PRESEND,
 181                                                &eff_buf, 0);
 182                 if (m < 0) {
 183                         lwsl_err("ext reports fatal error\n");
 184                         return -1;
 185                 }
 186                 if (m)
 187                         /*
 188                          * at least one extension told us he has more
 189                          * to spill, so we will go around again after
 190                          */
 191                         ret = 1;
 192
 193                 /* assuming they gave us something to send, send it */
 194
 195                 if (eff_buf.token_len) {
 196                         n = lws_issue_raw(wsi, (unsigned char *)eff_buf.token,
 197                                           eff_buf.token_len);
 198                         if (n < 0) {
 199                                 lwsl_info("closing from POLLOUT spill\n");
 200                                 return -1;
 201                         }
 202                         /*
 203                          * Keep amount spilled small to minimize chance of this
 204                          */
 205                         if (n != eff_buf.token_len) {
 206                                 lwsl_err("Unable to spill ext %d vs %s\n",
 207                                                           eff_buf.token_len, n);
 208                                 return -1;
 209                         }
 210                 } else
 211                         continue;
 212
 213                 /* no extension has more to spill */
 214
 215                 if (!ret)
 216                         continue;
 217
 218                 /*
 219                  * There's more to spill from an extension, but we just sent
 220                  * something... did that leave the pipe choked?
 221                  */
 222
 223                 if (!lws_send_pipe_choked(wsi))
 224                         /* no we could add more */
 225                         continue;
 226
 227                 lwsl_info("choked in POLLOUT service\n");
 228
 229                 /*
 230                  * Yes, he's choked.  Leave the POLLOUT masked on so we will
 231                  * come back here when he is unchoked.  Don't call the user
 232                  * callback to enforce ordering of spilling, he'll get called
 233                  * when we come back here and there's nothing more to spill.
 234                  */
 235
 236                 return 0;
 237         }
 238 #ifndef LWS_NO_EXTENSIONS
 239         wsi->extension_data_pending = 0;
 240 #endif
 241 user_service:
 242         /* one shot */
 243
 244         if (pollfd)
 245                 if (lws_change_pollfd(wsi, LWS_POLLOUT, 0)) {
 246                         lwsl_info("failed at set pollfd\n");
 247                         return 1;
 248                 }
 249
 250
 251         if (!wsi->hdr_parsing_completed)
 252                 return 0;
 253
 254 #ifdef LWS_WITH_CGI
 255 user_service_go_again:
 256 #endif
 257
 258 #ifdef LWS_USE_HTTP2
 259         /*
 260          * we are the 'network wsi' for potentially many muxed child wsi with
 261          * no network connection of their own, who have to use us for all their
 262          * network actions.  So we use a round-robin scheme to share out the
 263          * POLLOUT notifications to our children.
 264          *
 265          * But because any child could exhaust the socket's ability to take
 266          * writes, we can only let one child get notified each time.
 267          *
 268          * In addition children may be closed / deleted / added between POLLOUT
 269          * notifications, so we can't hold pointers
 270          */
 271
 272         if (wsi->mode != LWSCM_HTTP2_SERVING) {
 273                 lwsl_info("%s: non http2\n", __func__);
 274                 goto notify;
 275         }
 276
 277         wsi->u.http2.requested_POLLOUT = 0;
 278         if (!wsi->u.http2.initialized) {
 279                 lwsl_info("pollout on uninitialized http2 conn\n");
 280                 return 0;
 281         }
 282
 283         lwsl_info("%s: doing children\n", __func__);
 284
 285         wsi2 = wsi;
 286         do {
 287                 wsi2 = wsi2->u.http2.next_child_wsi;
 288                 lwsl_info("%s: child %p\n", __func__, wsi2);
 289                 if (!wsi2)
 290                         continue;
 291                 if (!wsi2->u.http2.requested_POLLOUT)
 292                         continue;
 293                 wsi2->u.http2.requested_POLLOUT = 0;
 294                 if (lws_calllback_as_writeable(wsi2)) {
 295                         lwsl_debug("Closing POLLOUT child\n");
 296                         lws_close_free_wsi(wsi2, LWS_CLOSE_STATUS_NOSTATUS);
 297                 }
 298                 wsi2 = wsi;
 299         } while (wsi2 != NULL && !lws_send_pipe_choked(wsi));
 300
 301         lwsl_info("%s: completed\n", __func__);
 302
 303         return 0;
 304 notify:
 305 #endif
 306         return lws_calllback_as_writeable(wsi);
 307 }
 308
 309 int
 310 lws_service_timeout_check(struct lws *wsi, unsigned int sec)
 311 {
 312         struct lws_context_per_thread *pt = &wsi->context->pt[(int)wsi->tsi];
 313
 314         /*
 315          * if extensions want in on it (eg, we are a mux parent)
 316          * give them a chance to service child timeouts
 317          */
 318         if (lws_ext_cb_active(wsi, LWS_EXT_CB_1HZ, NULL, sec) < 0)
 319                 return 0;
 320
 321         if (!wsi->pending_timeout)
 322                 return 0;
 323
 324         /*
 325          * if we went beyond the allowed time, kill the
 326          * connection
 327          */
 328         if ((time_t)sec > wsi->pending_timeout_limit) {
 329 #if LWS_POSIX
 330                 lwsl_notice("wsi %p: TIMEDOUT WAITING on %d (did hdr %d, ah %p, wl %d, pfd events %d)\n",
 331                             (void *)wsi, wsi->pending_timeout,
 332                             wsi->hdr_parsing_completed, wsi->u.hdr.ah,
 333                             pt->ah_wait_list_length,
 334                             pt->fds[wsi->sock].events);
 335 #endif
 336                 /*
 337                  * Since he failed a timeout, he already had a chance to do
 338                  * something and was unable to... that includes situations like
 339                  * half closed connections.  So process this "failed timeout"
 340                  * close as a violent death and don't try to do protocol
 341                  * cleanup like flush partials.
 342                  */
 343                 wsi->socket_is_permanently_unusable = 1;
 344                 lws_close_free_wsi(wsi, LWS_CLOSE_STATUS_NOSTATUS);
 345
 346                 return 1;
 347         }
 348
 349         return 0;
 350 }
 351
 352 int lws_rxflow_cache(struct lws *wsi, unsigned char *buf, int n, int len)
 353 {
 354         /* his RX is flowcontrolled, don't send remaining now */
 355         if (wsi->rxflow_buffer) {
 356                 /* rxflow while we were spilling prev rxflow */
 357                 lwsl_info("stalling in existing rxflow buf\n");
 358                 return 1;
 359         }
 360
 361         /* a new rxflow, buffer it and warn caller */
 362         lwsl_info("new rxflow input buffer len %d\n", len - n);
 363         wsi->rxflow_buffer = lws_malloc(len - n);
 364         wsi->rxflow_len = len - n;
 365         wsi->rxflow_pos = 0;
 366         memcpy(wsi->rxflow_buffer, buf + n, len - n);
 367
 368         return 0;
 369 }
 370
 371 /* this is used by the platform service code to stop us waiting for network
 372  * activity in poll() when we have something that already needs service
 373  */
 374
 375 int
 376 lws_service_adjust_timeout(struct lws_context *context, int timeout_ms, int tsi)
 377 {
 378         struct lws_context_per_thread *pt = &context->pt[tsi];
 379         int n;
 380
 381         /* Figure out if we really want to wait in poll()
 382          * We only need to wait if really nothing already to do and we have
 383          * to wait for something from network
 384          */
 385
 386         /* 1) if we know we are draining rx ext, do not wait in poll */
 387         if (pt->rx_draining_ext_list)
 388                 return 0;
 389
 390 #ifdef LWS_OPENSSL_SUPPORT
 391         /* 2) if we know we have non-network pending data, do not wait in poll */
 392         if (lws_ssl_anybody_has_buffered_read_tsi(context, tsi)) {
 393                 lwsl_info("ssl buffered read\n");
 394                 return 0;
 395         }
 396 #endif
 397
 398         /* 3) if any ah has pending rx, do not wait in poll */
 399         for (n = 0; n < context->max_http_header_pool; n++)
 400                 if (pt->ah_pool[n].rxpos != pt->ah_pool[n].rxlen) {
 401                         /* any ah with pending rx must be attached to someone */
 402                         assert(pt->ah_pool[n].wsi);
 403                         return 0;
 404                 }
 405
 406         return timeout_ms;
 407 }
 408
 409 /*
 410  * guys that need POLLIN service again without waiting for network action
 411  * can force POLLIN here if not flowcontrolled, so they will get service.
 412  *
 413  * Return nonzero if anybody got their POLLIN faked
 414  */
 415 int
 416 lws_service_flag_pending(struct lws_context *context, int tsi)
 417 {
 418         struct lws_context_per_thread *pt = &context->pt[tsi];
 419 #ifdef LWS_OPENSSL_SUPPORT
 420         struct lws *wsi_next;
 421 #endif
 422         struct lws *wsi;
 423         int forced = 0;
 424         int n;
 425
 426         /* POLLIN faking */
 427
 428         /*
 429          * 1) For all guys with already-available ext data to drain, if they are
 430          * not flowcontrolled, fake their POLLIN status
 431          */
 432         wsi = pt->rx_draining_ext_list;
 433         while (wsi) {
 434                 pt->fds[wsi->position_in_fds_table].revents |=
 435                         pt->fds[wsi->position_in_fds_table].events & LWS_POLLIN;
 436                 if (pt->fds[wsi->position_in_fds_table].revents &
 437                     LWS_POLLIN)
 438                         forced = 1;
 439                 wsi = wsi->u.ws.rx_draining_ext_list;
 440         }
 441
 442 #ifdef LWS_OPENSSL_SUPPORT
 443         /*
 444          * 2) For all guys with buffered SSL read data already saved up, if they
 445          * are not flowcontrolled, fake their POLLIN status so they'll get
 446          * service to use up the buffered incoming data, even though their
 447          * network socket may have nothing
 448          */
 449         wsi = pt->pending_read_list;
 450         while (wsi) {
 451                 wsi_next = wsi->pending_read_list_next;
 452                 pt->fds[wsi->position_in_fds_table].revents |=
 453                         pt->fds[wsi->position_in_fds_table].events & LWS_POLLIN;
 454                 if (pt->fds[wsi->position_in_fds_table].revents & LWS_POLLIN) {
 455                         forced = 1;
 456                         /*
 457                          * he's going to get serviced now, take him off the
 458                          * list of guys with buffered SSL.  If he still has some
 459                          * at the end of the service, he'll get put back on the
 460                          * list then.
 461                          */
 462                         lws_ssl_remove_wsi_from_buffered_list(wsi);
 463                 }
 464
 465                 wsi = wsi_next;
 466         }
 467 #endif
 468         /*
 469          * 3) For any wsi who have an ah with pending RX who did not
 470          * complete their current headers, and are not flowcontrolled,
 471          * fake their POLLIN status so they will be able to drain the
 472          * rx buffered in the ah
 473          */
 474         for (n = 0; n < context->max_http_header_pool; n++)
 475                 if (pt->ah_pool[n].rxpos != pt->ah_pool[n].rxlen &&
 476                     !pt->ah_pool[n].wsi->hdr_parsing_completed) {
 477                         pt->fds[pt->ah_pool[n].wsi->position_in_fds_table].revents |=
 478                                 pt->fds[pt->ah_pool[n].wsi->position_in_fds_table].events &
 479                                         LWS_POLLIN;
 480                         if (pt->fds[pt->ah_pool[n].wsi->position_in_fds_table].revents &
 481                             LWS_POLLIN)
 482                                 forced = 1;
 483                 }
 484
 485         return forced;
 486 }
 487
 488 #ifndef LWS_NO_CLIENT
 489
 490 LWS_VISIBLE int
 491 lws_http_client_read(struct lws *wsi, char **buf, int *len)
 492 {
 493         int rlen, n;
 494
 495         rlen = lws_ssl_capable_read(wsi, (unsigned char *)*buf, *len);
 496         if (rlen < 0)
 497                 return -1;
 498
 499         *len = rlen;
 500         if (rlen == 0)
 501                 return 0;
 502
 503 //      lwsl_err("%s: read %d\n", __func__, rlen);
 504
 505         /* allow the source to signal he has data again next time */
 506         wsi->client_rx_avail = 0;
 507         lws_change_pollfd(wsi, 0, LWS_POLLIN);
 508
 509         /*
 510          * server may insist on transfer-encoding: chunked,
 511          * so http client must deal with it
 512          */
 513 spin_chunks:
 514         while (wsi->chunked && (wsi->chunk_parser != ELCP_CONTENT) && *len) {
 515                 switch (wsi->chunk_parser) {
 516                 case ELCP_HEX:
 517                         if ((*buf)[0] == '\x0d') {
 518                                 wsi->chunk_parser = ELCP_CR;
 519                                 break;
 520                         }
 521                         n = char_to_hex((*buf)[0]);
 522                         if (n < 0)
 523                                 return -1;
 524                         wsi->chunk_remaining <<= 4;
 525                         wsi->chunk_remaining |= n;
 526                         break;
 527                 case ELCP_CR:
 528                         if ((*buf)[0] != '\x0a')
 529                                 return -1;
 530                         wsi->chunk_parser = ELCP_CONTENT;
 531                         lwsl_info("chunk %d\n", wsi->chunk_remaining);
 532                         if (wsi->chunk_remaining)
 533                                 break;
 534                         lwsl_info("final chunk\n");
 535                         goto completed;
 536
 537                 case ELCP_CONTENT:
 538                         break;
 539
 540                 case ELCP_POST_CR:
 541                         if ((*buf)[0] != '\x0d')
 542                                 return -1;
 543
 544                         wsi->chunk_parser = ELCP_POST_LF;
 545                         break;
 546
 547                 case ELCP_POST_LF:
 548                         if ((*buf)[0] != '\x0a')
 549                                 return -1;
 550
 551                         wsi->chunk_parser = ELCP_HEX;
 552                         wsi->chunk_remaining = 0;
 553                         break;
 554                 }
 555                 (*buf)++;
 556                 (*len)--;
 557         }
 558
 559         if (wsi->chunked && !wsi->chunk_remaining)
 560                 return 0;
 561
 562         if (wsi->u.http.content_remain &&
 563             (int)wsi->u.http.content_remain < *len)
 564                 n = wsi->u.http.content_remain;
 565         else
 566                 n = *len;
 567
 568         if (wsi->chunked && wsi->chunk_remaining &&
 569             wsi->chunk_remaining < n)
 570                 n = wsi->chunk_remaining;
 571
 572 #ifdef LWS_WITH_HTTP_PROXY
 573         /* hubbub */
 574         if (wsi->perform_rewrite)
 575                 lws_rewrite_parse(wsi->rw, (unsigned char *)*buf, n);
 576         else
 577 #endif
 578                 if (user_callback_handle_rxflow(wsi->protocol->callback,
 579                                 wsi, LWS_CALLBACK_RECEIVE_CLIENT_HTTP_READ,
 580                                 wsi->user_space, *buf, n))
 581                         return -1;
 582
 583         if (wsi->chunked && wsi->chunk_remaining) {
 584                 (*buf) += n;
 585                 wsi->chunk_remaining -= n;
 586                 *len -= n;
 587         }
 588
 589         if (wsi->chunked && !wsi->chunk_remaining)
 590                 wsi->chunk_parser = ELCP_POST_CR;
 591
 592         if (wsi->chunked && *len) {
 593                 goto spin_chunks;
 594         }
 595
 596         if (wsi->chunked)
 597                 return 0;
 598
 599         wsi->u.http.content_remain -= n;
 600         if (wsi->u.http.content_remain || !wsi->u.http.content_length)
 601                 return 0;
 602
 603 completed:
 604         if (user_callback_handle_rxflow(wsi->protocol->callback,
 605                         wsi, LWS_CALLBACK_COMPLETED_CLIENT_HTTP,
 606                         wsi->user_space, NULL, 0))
 607                 return -1;
 608
 609         if (lws_http_transaction_completed_client(wsi))
 610                 return -1;
 611
 612         return 0;
 613 }
 614 #endif
 615
 616 /**
 617  * lws_service_fd() - Service polled socket with something waiting
 618  * @context:    Websocket context
 619  * @pollfd:     The pollfd entry describing the socket fd and which events
 620  *              happened.
 621  *
 622  *      This function takes a pollfd that has POLLIN or POLLOUT activity and
 623  *      services it according to the state of the associated
 624  *      struct lws.
 625  *
 626  *      The one call deals with all "service" that might happen on a socket
 627  *      including listen accepts, http files as well as websocket protocol.
 628  *
 629  *      If a pollfd says it has something, you can just pass it to
 630  *      lws_service_fd() whether it is a socket handled by lws or not.
 631  *      If it sees it is a lws socket, the traffic will be handled and
 632  *      pollfd->revents will be zeroed now.
 633  *
 634  *      If the socket is foreign to lws, it leaves revents alone.  So you can
 635  *      see if you should service yourself by checking the pollfd revents
 636  *      after letting lws try to service it.
 637  */
 638
 639 LWS_VISIBLE int
 640 lws_service_fd_tsi(struct lws_context *context, struct lws_pollfd *pollfd, int tsi)
 641 {
 642         struct lws_context_per_thread *pt = &context->pt[tsi];
 643         lws_sockfd_type our_fd = 0, tmp_fd;
 644         struct lws_tokens eff_buf;
 645         unsigned int pending = 0;
 646         struct lws *wsi, *wsi1;
 647         char draining_flow = 0;
 648         int timed_out = 0;
 649         time_t now;
 650         int n = 0, m;
 651         int more;
 652
 653         if (!context->protocol_init_done)
 654                 lws_protocol_init(context);
 655
 656         /*
 657          * you can call us with pollfd = NULL to just allow the once-per-second
 658          * global timeout checks; if less than a second since the last check
 659          * it returns immediately then.
 660          */
 661
 662         time(&now);
 663
 664         /* TODO: if using libev, we should probably use timeout watchers... */
 665         if (context->last_timeout_check_s != now) {
 666                 context->last_timeout_check_s = now;
 667
 668                 lws_plat_service_periodic(context);
 669
 670                 /* global timeout check once per second */
 671
 672                 if (pollfd)
 673                         our_fd = pollfd->fd;
 674
 675                 wsi = context->pt[tsi].timeout_list;
 676                 while (wsi) {
 677                         /* we have to take copies, because he may be deleted */
 678                         wsi1 = wsi->timeout_list;
 679                         tmp_fd = wsi->sock;
 680                         if (lws_service_timeout_check(wsi, (unsigned int)now)) {
 681                                 /* he did time out... */
 682                                 if (tmp_fd == our_fd)
 683                                         /* it was the guy we came to service! */
 684                                         timed_out = 1;
 685                                         /* he's gone, no need to mark as handled */
 686                         }
 687                         wsi = wsi1;
 688                 }
 689 #ifdef LWS_WITH_CGI
 690                 lws_cgi_kill_terminated(pt);
 691 #endif
 692 #if 0
 693                 {
 694                         char s[300], *p = s;
 695
 696                         for (n = 0; n < context->count_threads; n++)
 697                                 p += sprintf(p, " %7lu (%5d), ",
 698                                              context->pt[n].count_conns,
 699                                              context->pt[n].fds_count);
 700
 701                         lwsl_notice("load: %s\n", s);
 702                 }
 703 #endif
 704         }
 705
 706         /* the socket we came to service timed out, nothing to do */
 707         if (timed_out)
 708                 return 0;
 709
 710         /* just here for timeout management? */
 711         if (!pollfd)
 712                 return 0;
 713
 714         /* no, here to service a socket descriptor */
 715         wsi = wsi_from_fd(context, pollfd->fd);
 716         if (!wsi)
 717                 /* not lws connection ... leave revents alone and return */
 718                 return 0;
 719
 720         /*
 721          * so that caller can tell we handled, past here we need to
 722          * zero down pollfd->revents after handling
 723          */
 724
 725 #if LWS_POSIX
 726         /* handle session socket closed */
 727
 728         if ((!(pollfd->revents & pollfd->events & LWS_POLLIN)) &&
 729             (pollfd->revents & LWS_POLLHUP)) {
 730                 wsi->socket_is_permanently_unusable = 1;
 731                 lwsl_debug("Session Socket %p (fd=%d) dead\n",
 732                                                        (void *)wsi, pollfd->fd);
 733
 734                 goto close_and_handled;
 735         }
 736
 737 #ifdef _WIN32
 738         if (pollfd->revents & LWS_POLLOUT)
 739                 wsi->sock_send_blocking = FALSE;
 740 #endif
 741
 742 #endif
 743
 744         lwsl_debug("fd=%d, revents=%d\n", pollfd->fd, pollfd->revents);
 745
 746         /* okay, what we came here to do... */
 747
 748         switch (wsi->mode) {
 749         case LWSCM_HTTP_SERVING:
 750         case LWSCM_HTTP_CLIENT:
 751         case LWSCM_HTTP_SERVING_ACCEPTED:
 752         case LWSCM_SERVER_LISTENER:
 753         case LWSCM_SSL_ACK_PENDING:
 754                 if (wsi->state == LWSS_CLIENT_HTTP_ESTABLISHED)
 755                         goto handled;
 756
 757 #ifdef LWS_WITH_CGI
 758                 if (wsi->cgi && (pollfd->revents & LWS_POLLOUT)) {
 759                         n = lws_handle_POLLOUT_event(wsi, pollfd);
 760                         if (n)
 761                                 goto close_and_handled;
 762                         goto handled;
 763                 }
 764 #endif
 765                 n = lws_server_socket_service(context, wsi, pollfd);
 766                 if (n) /* closed by above */
 767                         return 1;
 768                 goto handled;
 769
 770         case LWSCM_WS_SERVING:
 771         case LWSCM_WS_CLIENT:
 772         case LWSCM_HTTP2_SERVING:
 773         case LWSCM_HTTP_CLIENT_ACCEPTED:
 774
 775                 /* 1: something requested a callback when it was OK to write */
 776
 777                 if ((pollfd->revents & LWS_POLLOUT) &&
 778                     (wsi->state == LWSS_ESTABLISHED ||
 779                      wsi->state == LWSS_HTTP2_ESTABLISHED ||
 780                      wsi->state == LWSS_HTTP2_ESTABLISHED_PRE_SETTINGS ||
 781                      wsi->state == LWSS_RETURNED_CLOSE_ALREADY ||
 782                      wsi->state == LWSS_FLUSHING_STORED_SEND_BEFORE_CLOSE) &&
 783                     lws_handle_POLLOUT_event(wsi, pollfd)) {
 784                         if (wsi->state == LWSS_RETURNED_CLOSE_ALREADY)
 785                                 wsi->state = LWSS_FLUSHING_STORED_SEND_BEFORE_CLOSE;
 786                         lwsl_info("lws_service_fd: closing\n");
 787                         goto close_and_handled;
 788                 }
 789
 790                 if (wsi->state == LWSS_RETURNED_CLOSE_ALREADY ||
 791                     wsi->state == LWSS_AWAITING_CLOSE_ACK) {
 792                         /*
 793                          * we stopped caring about anything except control
 794                          * packets.  Force flow control off, defeat tx
 795                          * draining.
 796                          */
 797                         lws_rx_flow_control(wsi, 1);
 798                         wsi->u.ws.tx_draining_ext = 0;
 799                 }
 800
 801                 if (wsi->u.ws.tx_draining_ext)
 802                         /* we cannot deal with new RX until the TX ext
 803                          * path has been drained.  It's because new
 804                          * rx will, eg, crap on the wsi rx buf that
 805                          * may be needed to retain state.
 806                          *
 807                          * TX ext drain path MUST go through event loop
 808                          * to avoid blocking.
 809                          */
 810                         break;
 811
 812                 if (!(wsi->rxflow_change_to & LWS_RXFLOW_ALLOW))
 813                         /* We cannot deal with any kind of new RX
 814                          * because we are RX-flowcontrolled.
 815                          */
 816                         break;
 817
 818                 /* 2: RX Extension needs to be drained
 819                  */
 820
 821                 if (wsi->state == LWSS_ESTABLISHED &&
 822                     wsi->u.ws.rx_draining_ext) {
 823
 824                         lwsl_ext("%s: RX EXT DRAINING: Service\n", __func__);
 825 #ifndef LWS_NO_CLIENT
 826                         if (wsi->mode == LWSCM_WS_CLIENT) {
 827                                 n = lws_client_rx_sm(wsi, 0);
 828                                 if (n < 0)
 829                                         /* we closed wsi */
 830                                         n = 0;
 831                         } else
 832 #endif
 833                                 n = lws_rx_sm(wsi, 0);
 834
 835                         goto handled;
 836                 }
 837
 838                 if (wsi->u.ws.rx_draining_ext)
 839                         /*
 840                          * We have RX EXT content to drain, but can't do it
 841                          * right now.  That means we cannot do anything lower
 842                          * priority either.
 843                          */
 844                         break;
 845
 846                 /* 3: RX Flowcontrol buffer needs to be drained
 847                  */
 848
 849                 if (wsi->rxflow_buffer) {
 850                         lwsl_info("draining rxflow (len %d)\n",
 851                                 wsi->rxflow_len - wsi->rxflow_pos
 852                         );
 853                         /* well, drain it */
 854                         eff_buf.token = (char *)wsi->rxflow_buffer +
 855                                                 wsi->rxflow_pos;
 856                         eff_buf.token_len = wsi->rxflow_len - wsi->rxflow_pos;
 857                         draining_flow = 1;
 858                         goto drain;
 859                 }
 860
 861                 /* 4: any incoming (or ah-stashed incoming rx) data ready?
 862                  * notice if rx flow going off raced poll(), rx flow wins
 863                  */
 864
 865                 if (!(pollfd->revents & pollfd->events & LWS_POLLIN))
 866                         break;
 867
 868 read:
 869                 /* all the union members start with hdr, so even in ws mode
 870                  * we can deal with the ah via u.hdr
 871                  */
 872                 if (wsi->u.hdr.ah) {
 873                         lwsl_info("%s: %p: inherited ah rx\n", __func__, wsi);
 874                         eff_buf.token_len = wsi->u.hdr.ah->rxlen -
 875                                             wsi->u.hdr.ah->rxpos;
 876                         eff_buf.token = (char *)wsi->u.hdr.ah->rx +
 877                                         wsi->u.hdr.ah->rxpos;
 878                 } else {
 879                         if (wsi->mode != LWSCM_HTTP_CLIENT_ACCEPTED) {
 880                                 eff_buf.token_len = lws_ssl_capable_read(wsi,
 881                                         pt->serv_buf, pending ? pending :
 882                                                         LWS_MAX_SOCKET_IO_BUF);
 883                                 switch (eff_buf.token_len) {
 884                                 case 0:
 885                                         lwsl_info("%s: zero length read\n", __func__);
 886                                         goto close_and_handled;
 887                                 case LWS_SSL_CAPABLE_MORE_SERVICE:
 888                                         lwsl_info("SSL Capable more service\n");
 889                                         n = 0;
 890                                         goto handled;
 891                                 case LWS_SSL_CAPABLE_ERROR:
 892                                         lwsl_info("Closing when error\n");
 893                                         goto close_and_handled;
 894                                 }
 895
 896                                 eff_buf.token = (char *)pt->serv_buf;
 897                         }
 898                 }
 899
 900 drain:
 901 #ifndef LWS_NO_CLIENT
 902                 if (wsi->mode == LWSCM_HTTP_CLIENT_ACCEPTED) {
 903
 904                         /*
 905                          * simply mark ourselves as having readable data
 906                          * and turn off our POLLIN
 907                          */
 908                         wsi->client_rx_avail = 1;
 909                         lws_change_pollfd(wsi, LWS_POLLIN, 0);
 910
 911                         /* let user code know, he'll usually ask for writeable
 912                          * callback and drain / reenable it there
 913                          */
 914                         if (user_callback_handle_rxflow(wsi->protocol->callback,
 915                                         wsi, LWS_CALLBACK_RECEIVE_CLIENT_HTTP,
 916                                         wsi->user_space, NULL, 0))
 917                                 goto close_and_handled;
 918                 }
 919 #endif
 920                 /*
 921                  * give any active extensions a chance to munge the buffer
 922                  * before parse.  We pass in a pointer to an lws_tokens struct
 923                  * prepared with the default buffer and content length that's in
 924                  * there.  Rather than rewrite the default buffer, extensions
 925                  * that expect to grow the buffer can adapt .token to
 926                  * point to their own per-connection buffer in the extension
 927                  * user allocation.  By default with no extensions or no
 928                  * extension callback handling, just the normal input buffer is
 929                  * used then so it is efficient.
 930                  */
 931                 do {
 932                         more = 0;
 933
 934                         m = lws_ext_cb_active(wsi, LWS_EXT_CB_PACKET_RX_PREPARSE,
 935                                               &eff_buf, 0);
 936                         if (m < 0)
 937                                 goto close_and_handled;
 938                         if (m)
 939                                 more = 1;
 940
 941                         /* service incoming data */
 942
 943                         if (eff_buf.token_len) {
 944                                 /*
 945                                  * if draining from rxflow buffer, not
 946                                  * critical to track what was used since at the
 947                                  * use it bumps wsi->rxflow_pos.  If we come
 948                                  * around again it will pick up from where it
 949                                  * left off.
 950                                  */
 951                                 n = lws_read(wsi, (unsigned char *)eff_buf.token,
 952                                              eff_buf.token_len);
 953                                 if (n < 0) {
 954                                         /* we closed wsi */
 955                                         n = 0;
 956                                         goto handled;
 957                                 }
 958                         }
 959
 960                         eff_buf.token = NULL;
 961                         eff_buf.token_len = 0;
 962                 } while (more);
 963
 964                 if (wsi->u.hdr.ah) {
 965                         lwsl_info("%s: %p: detaching inherited used ah\n",
 966                                  __func__, wsi);
 967                         /* show we used all the pending rx up */
 968                         wsi->u.hdr.ah->rxpos = wsi->u.hdr.ah->rxlen;
 969                         /* we can run the normal ah detach flow despite
 970                          * being in ws union mode, since all union members
 971                          * start with hdr */
 972                         lws_header_table_detach(wsi, 0);
 973                 }
 974
 975                 pending = lws_ssl_pending(wsi);
 976                 if (pending) {
 977                         pending = pending > LWS_MAX_SOCKET_IO_BUF ?
 978                                         LWS_MAX_SOCKET_IO_BUF : pending;
 979                         goto read;
 980                 }
 981
 982                 if (draining_flow && wsi->rxflow_buffer &&
 983                     wsi->rxflow_pos == wsi->rxflow_len) {
 984                         lwsl_info("flow buffer: drained\n");
 985                         lws_free_set_NULL(wsi->rxflow_buffer);
 986                         /* having drained the rxflow buffer, can rearm POLLIN */
 987 #ifdef LWS_NO_SERVER
 988                         n =
 989 #endif
 990                         _lws_rx_flow_control(wsi);
 991                         /* n ignored, needed for NO_SERVER case */
 992                 }
 993
 994                 break;
 995 #ifdef LWS_WITH_CGI
 996         case LWSCM_CGI: /* we exist to handle a cgi's stdin/out/err data...
 997                          * do the callback on our master wsi
 998                          */
 999                 {
1000                         struct lws_cgi_args args;
1001
1002                         if (wsi->cgi_channel >= LWS_STDOUT &&
1003                             !(pollfd->revents & pollfd->events & LWS_POLLIN))
1004                                 break;
1005                         if (wsi->cgi_channel == LWS_STDIN &&
1006                             !(pollfd->revents & pollfd->events & LWS_POLLOUT))
1007                                 break;
1008
1009                         if (wsi->cgi_channel == LWS_STDIN)
1010                                 if (lws_change_pollfd(wsi, LWS_POLLOUT, 0)) {
1011                                         lwsl_info("failed at set pollfd\n");
1012                                         return 1;
1013                                 }
1014
1015                         args.ch = wsi->cgi_channel;
1016                         args.stdwsi = &wsi->parent->cgi->stdwsi[0];
1017                         args.hdr_state = wsi->hdr_state;
1018
1019                         //lwsl_err("CGI LWS_STDOUT waiting wsi %p mode %d state %d\n",
1020                         //       wsi->parent, wsi->parent->mode, wsi->parent->state);
1021
1022                         if (user_callback_handle_rxflow(
1023                                         wsi->parent->protocol->callback,
1024                                         wsi->parent, LWS_CALLBACK_CGI,
1025                                         wsi->parent->user_space,
1026                                         (void *)&args, 0))
1027                                 return 1;
1028
1029                         break;
1030                 }
1031 #endif
1032         default:
1033 #ifdef LWS_NO_CLIENT
1034                 break;
1035 #else
1036                 n = lws_client_socket_service(context, wsi, pollfd);
1037                 if (n)
1038                         return 1;
1039                 goto handled;
1040 #endif
1041         }
1042
1043         n = 0;
1044         goto handled;
1045
1046 close_and_handled:
1047         lwsl_debug("Close and handled\n");
1048         lws_close_free_wsi(wsi, LWS_CLOSE_STATUS_NOSTATUS);
1049         /*
1050          * pollfd may point to something else after the close
1051          * due to pollfd swapping scheme on delete on some platforms
1052          * we can't clear revents now because it'd be the wrong guy's revents
1053          */
1054         return 1;
1055
1056 handled:
1057         pollfd->revents = 0;
1058         return n;
1059 }
1060
1061 LWS_VISIBLE int
1062 lws_service_fd(struct lws_context *context, struct lws_pollfd *pollfd)
1063 {
1064         return lws_service_fd_tsi(context, pollfd, 0);
1065 }
1066
1067 /**
1068  * lws_service() - Service any pending websocket activity
1069  * @context:    Websocket context
1070  * @timeout_ms: Timeout for poll; 0 means return immediately if nothing needed
1071  *              service otherwise block and service immediately, returning
1072  *              after the timeout if nothing needed service.
1073  *
1074  *      This function deals with any pending websocket traffic, for three
1075  *      kinds of event.  It handles these events on both server and client
1076  *      types of connection the same.
1077  *
1078  *      1) Accept new connections to our context's server
1079  *
1080  *      2) Call the receive callback for incoming frame data received by
1081  *          server or client connections.
1082  *
1083  *      You need to call this service function periodically to all the above
1084  *      functions to happen; if your application is single-threaded you can
1085  *      just call it in your main event loop.
1086  *
1087  *      Alternatively you can fork a new process that asynchronously handles
1088  *      calling this service in a loop.  In that case you are happy if this
1089  *      call blocks your thread until it needs to take care of something and
1090  *      would call it with a large nonzero timeout.  Your loop then takes no
1091  *      CPU while there is nothing happening.
1092  *
1093  *      If you are calling it in a single-threaded app, you don't want it to
1094  *      wait around blocking other things in your loop from happening, so you
1095  *      would call it with a timeout_ms of 0, so it returns immediately if
1096  *      nothing is pending, or as soon as it services whatever was pending.
1097  */
1098
1099 LWS_VISIBLE int
1100 lws_service(struct lws_context *context, int timeout_ms)
1101 {
1102         return lws_plat_service(context, timeout_ms);
1103 }
1104
1105 LWS_VISIBLE int
1106 lws_service_tsi(struct lws_context *context, int timeout_ms, int tsi)
1107 {
1108         return lws_plat_service_tsi(context, timeout_ms, tsi);
1109 }
1110