lib/pollfd.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 int
  25 _lws_change_pollfd(struct lws *wsi, int _and, int _or, struct lws_pollargs *pa)
  26 {
  27         struct lws_context_per_thread *pt;
  28         struct lws_context *context;
  29         int ret = 0, pa_events = 1;
  30         struct lws_pollfd *pfd;
  31         int sampled_tid, tid;
  32
  33         if (!wsi || wsi->position_in_fds_table < 0)
  34                 return 0;
  35
  36         if (wsi->handling_pollout && !_and && _or == LWS_POLLOUT) {
  37                 /*
  38                  * Happening alongside service thread handling POLLOUT.
  39                  * The danger is when he is finished, he will disable POLLOUT,
  40                  * countermanding what we changed here.
  41                  *
  42                  * Instead of changing the fds, inform the service thread
  43                  * what happened, and ask it to leave POLLOUT active on exit
  44                  */
  45                 wsi->leave_pollout_active = 1;
  46                 /*
  47                  * by definition service thread is not in poll wait, so no need
  48                  * to cancel service
  49                  */
  50
  51                 lwsl_debug("%s: using leave_pollout_active\n", __func__);
  52
  53                 return 0;
  54         }
  55
  56         context = wsi->context;
  57         pt = &context->pt[(int)wsi->tsi];
  58         assert(wsi->position_in_fds_table >= 0 &&
  59                wsi->position_in_fds_table < pt->fds_count);
  60
  61         pfd = &pt->fds[wsi->position_in_fds_table];
  62         pa->fd = wsi->desc.sockfd;
  63         pa->prev_events = pfd->events;
  64         pa->events = pfd->events = (pfd->events & ~_and) | _or;
  65
  66         //lwsl_notice("%s: wsi %p, posin %d. from %d -> %d\n", __func__, wsi, wsi->position_in_fds_table, pa->prev_events, pa->events);
  67
  68
  69         if (wsi->http2_substream)
  70                 return 0;
  71
  72         if (wsi->vhost->protocols[0].callback(wsi, LWS_CALLBACK_CHANGE_MODE_POLL_FD,
  73                                            wsi->user_space, (void *)pa, 0)) {
  74                 ret = -1;
  75                 goto bail;
  76         }
  77
  78         if (_and & LWS_POLLIN) {
  79                 lws_libev_io(wsi, LWS_EV_STOP | LWS_EV_READ);
  80                 lws_libuv_io(wsi, LWS_EV_STOP | LWS_EV_READ);
  81                 lws_libevent_io(wsi, LWS_EV_STOP | LWS_EV_READ);
  82         }
  83         if (_or & LWS_POLLIN) {
  84                 lws_libev_io(wsi, LWS_EV_START | LWS_EV_READ);
  85                 lws_libuv_io(wsi, LWS_EV_START | LWS_EV_READ);
  86                 lws_libevent_io(wsi, LWS_EV_START | LWS_EV_READ);
  87         }
  88         if (_and & LWS_POLLOUT) {
  89                 lws_libev_io(wsi, LWS_EV_STOP | LWS_EV_WRITE);
  90                 lws_libuv_io(wsi, LWS_EV_STOP | LWS_EV_WRITE);
  91                 lws_libevent_io(wsi, LWS_EV_STOP | LWS_EV_WRITE);
  92         }
  93         if (_or & LWS_POLLOUT) {
  94                 lws_libev_io(wsi, LWS_EV_START | LWS_EV_WRITE);
  95                 lws_libuv_io(wsi, LWS_EV_START | LWS_EV_WRITE);
  96                 lws_libevent_io(wsi, LWS_EV_START | LWS_EV_WRITE);
  97         }
  98
  99         /*
 100          * if we changed something in this pollfd...
 101          *   ... and we're running in a different thread context
 102          *     than the service thread...
 103          *       ... and the service thread is waiting ...
 104          *         then cancel it to force a restart with our changed events
 105          */
 106 #if LWS_POSIX
 107         pa_events = pa->prev_events != pa->events;
 108 #endif
 109
 110         if (pa_events) {
 111
 112                 if (lws_plat_change_pollfd(context, wsi, pfd)) {
 113                         lwsl_info("%s failed\n", __func__);
 114                         ret = -1;
 115                         goto bail;
 116                 }
 117
 118                 sampled_tid = context->service_tid;
 119                 if (sampled_tid) {
 120                         tid = wsi->vhost->protocols[0].callback(wsi,
 121                                      LWS_CALLBACK_GET_THREAD_ID, NULL, NULL, 0);
 122                         if (tid == -1) {
 123                                 ret = -1;
 124                                 goto bail;
 125                         }
 126                         if (tid != sampled_tid)
 127                                 lws_cancel_service_pt(wsi);
 128                 }
 129         }
 130 bail:
 131         return ret;
 132 }
 133
 134 #ifndef LWS_NO_SERVER
 135 static void
 136 lws_accept_modulation(struct lws_context_per_thread *pt, int allow)
 137 {
 138 // multithread listen seems broken
 139 #if 0
 140         struct lws_vhost *vh = context->vhost_list;
 141         struct lws_pollargs pa1;
 142
 143         while (vh) {
 144                 if (allow)
 145                         _lws_change_pollfd(pt->wsi_listening,
 146                                            0, LWS_POLLIN, &pa1);
 147                 else
 148                         _lws_change_pollfd(pt->wsi_listening,
 149                                            LWS_POLLIN, 0, &pa1);
 150                 vh = vh->vhost_next;
 151         }
 152 #endif
 153 }
 154 #endif
 155
 156 int
 157 insert_wsi_socket_into_fds(struct lws_context *context, struct lws *wsi)
 158 {
 159         struct lws_pollargs pa = { wsi->desc.sockfd, LWS_POLLIN, 0 };
 160         struct lws_context_per_thread *pt = &context->pt[(int)wsi->tsi];
 161         int ret = 0;
 162
 163
 164         lwsl_debug("%s: %p: tsi=%d, sock=%d, pos-in-fds=%d\n",
 165                   __func__, wsi, wsi->tsi, wsi->desc.sockfd, pt->fds_count);
 166
 167         if ((unsigned int)pt->fds_count >= context->fd_limit_per_thread) {
 168                 lwsl_err("Too many fds (%d vs %d)\n", context->max_fds,
 169                                 context->fd_limit_per_thread    );
 170                 return 1;
 171         }
 172
 173 #if !defined(_WIN32) && !defined(LWS_WITH_ESP8266)
 174         if (wsi->desc.sockfd >= context->max_fds) {
 175                 lwsl_err("Socket fd %d is too high (%d)\n",
 176                          wsi->desc.sockfd, context->max_fds);
 177                 return 1;
 178         }
 179 #endif
 180
 181         assert(wsi);
 182         assert(wsi->vhost);
 183         assert(lws_socket_is_valid(wsi->desc.sockfd));
 184
 185         if (wsi->vhost->protocols[0].callback(wsi, LWS_CALLBACK_LOCK_POLL,
 186                                            wsi->user_space, (void *) &pa, 1))
 187                 return -1;
 188
 189         lws_pt_lock(pt);
 190         pt->count_conns++;
 191         insert_wsi(context, wsi);
 192 #if defined(LWS_WITH_ESP8266)
 193         if (wsi->position_in_fds_table == -1)
 194 #endif
 195                 wsi->position_in_fds_table = pt->fds_count;
 196
 197         // lwsl_notice("%s: %p: setting posinfds %d\n", __func__, wsi, wsi->position_in_fds_table);
 198
 199         pt->fds[wsi->position_in_fds_table].fd = wsi->desc.sockfd;
 200 #if LWS_POSIX
 201         pt->fds[wsi->position_in_fds_table].events = LWS_POLLIN;
 202 #else
 203         pt->fds[wsi->position_in_fds_table].events = 0; // LWS_POLLIN;
 204 #endif
 205         pa.events = pt->fds[pt->fds_count].events;
 206
 207         lws_plat_insert_socket_into_fds(context, wsi);
 208
 209         /* external POLL support via protocol 0 */
 210         if (wsi->vhost->protocols[0].callback(wsi, LWS_CALLBACK_ADD_POLL_FD,
 211                                            wsi->user_space, (void *) &pa, 0))
 212                 ret =  -1;
 213 #ifndef LWS_NO_SERVER
 214         /* if no more room, defeat accepts on this thread */
 215         if ((unsigned int)pt->fds_count == context->fd_limit_per_thread - 1)
 216                 lws_accept_modulation(pt, 0);
 217 #endif
 218         lws_pt_unlock(pt);
 219
 220         if (wsi->vhost->protocols[0].callback(wsi, LWS_CALLBACK_UNLOCK_POLL,
 221                                            wsi->user_space, (void *)&pa, 1))
 222                 ret = -1;
 223
 224         return ret;
 225 }
 226
 227 int
 228 remove_wsi_socket_from_fds(struct lws *wsi)
 229 {
 230         struct lws_context *context = wsi->context;
 231         struct lws_pollargs pa = { wsi->desc.sockfd, 0, 0 };
 232 #if !defined(LWS_WITH_ESP8266)
 233         struct lws_context_per_thread *pt = &context->pt[(int)wsi->tsi];
 234         struct lws *end_wsi;
 235         int v;
 236 #endif
 237         int m, ret = 0;
 238
 239 #if !defined(_WIN32) && !defined(LWS_WITH_ESP8266)
 240         if (wsi->desc.sockfd > context->max_fds) {
 241                 lwsl_err("fd %d too high (%d)\n", wsi->desc.sockfd, context->max_fds);
 242                 return 1;
 243         }
 244 #endif
 245
 246         if (wsi->vhost->protocols[0].callback(wsi, LWS_CALLBACK_LOCK_POLL,
 247                                            wsi->user_space, (void *)&pa, 1))
 248                 return -1;
 249
 250         lws_same_vh_protocol_remove(wsi);
 251
 252         /* the guy who is to be deleted's slot index in pt->fds */
 253         m = wsi->position_in_fds_table;
 254
 255 #if !defined(LWS_WITH_ESP8266)
 256         lws_libev_io(wsi, LWS_EV_STOP | LWS_EV_READ | LWS_EV_WRITE | LWS_EV_PREPARE_DELETION);
 257         lws_libuv_io(wsi, LWS_EV_STOP | LWS_EV_READ | LWS_EV_WRITE | LWS_EV_PREPARE_DELETION);
 258
 259         lws_pt_lock(pt);
 260
 261         lwsl_debug("%s: wsi=%p, sock=%d, fds pos=%d, end guy pos=%d, endfd=%d\n",
 262                   __func__, wsi, wsi->desc.sockfd, wsi->position_in_fds_table,
 263                   pt->fds_count, pt->fds[pt->fds_count].fd);
 264
 265         /* have the last guy take up the now vacant slot */
 266         pt->fds[m] = pt->fds[pt->fds_count - 1];
 267 #endif
 268         /* this decrements pt->fds_count */
 269         lws_plat_delete_socket_from_fds(context, wsi, m);
 270 #if !defined(LWS_WITH_ESP8266)
 271         v = (int) pt->fds[m].fd;
 272         /* end guy's "position in fds table" is now the deletion guy's old one */
 273         end_wsi = wsi_from_fd(context, v);
 274         if (!end_wsi) {
 275                 lwsl_err("no wsi found for sock fd %d at pos %d, pt->fds_count=%d\n", (int)pt->fds[m].fd, m, pt->fds_count);
 276                 assert(0);
 277         } else
 278                 end_wsi->position_in_fds_table = m;
 279
 280         /* deletion guy's lws_lookup entry needs nuking */
 281         delete_from_fd(context, wsi->desc.sockfd);
 282         /* removed wsi has no position any more */
 283         wsi->position_in_fds_table = -1;
 284
 285         /* remove also from external POLL support via protocol 0 */
 286         if (lws_socket_is_valid(wsi->desc.sockfd))
 287                 if (wsi->vhost->protocols[0].callback(wsi, LWS_CALLBACK_DEL_POLL_FD,
 288                                                    wsi->user_space, (void *) &pa, 0))
 289                         ret = -1;
 290 #ifndef LWS_NO_SERVER
 291         if (!context->being_destroyed)
 292                 /* if this made some room, accept connects on this thread */
 293                 if ((unsigned int)pt->fds_count < context->fd_limit_per_thread - 1)
 294                         lws_accept_modulation(pt, 1);
 295 #endif
 296         lws_pt_unlock(pt);
 297
 298         if (wsi->vhost->protocols[0].callback(wsi, LWS_CALLBACK_UNLOCK_POLL,
 299                                            wsi->user_space, (void *) &pa, 1))
 300                 ret = -1;
 301 #endif
 302         return ret;
 303 }
 304
 305 int
 306 lws_change_pollfd(struct lws *wsi, int _and, int _or)
 307 {
 308         struct lws_context_per_thread *pt;
 309         struct lws_context *context;
 310         struct lws_pollargs pa;
 311         int ret = 0;
 312
 313         if (!wsi || !wsi->protocol || wsi->position_in_fds_table < 0)
 314                 return 1;
 315
 316         context = lws_get_context(wsi);
 317         if (!context)
 318                 return 1;
 319
 320         if (wsi->vhost->protocols[0].callback(wsi, LWS_CALLBACK_LOCK_POLL,
 321                                            wsi->user_space,  (void *) &pa, 0))
 322                 return -1;
 323
 324         pt = &context->pt[(int)wsi->tsi];
 325
 326         lws_pt_lock(pt);
 327         ret = _lws_change_pollfd(wsi, _and, _or, &pa);
 328         lws_pt_unlock(pt);
 329         if (wsi->vhost->protocols[0].callback(wsi, LWS_CALLBACK_UNLOCK_POLL,
 330                                            wsi->user_space, (void *) &pa, 0))
 331                 ret = -1;
 332
 333         return ret;
 334 }
 335
 336 LWS_VISIBLE int
 337 lws_callback_on_writable(struct lws *wsi)
 338 {
 339         struct lws_context_per_thread *pt;
 340 #ifdef LWS_USE_HTTP2
 341         struct lws *network_wsi, *wsi2;
 342         int already;
 343 #endif
 344
 345         if (wsi->state == LWSS_SHUTDOWN)
 346                 return 0;
 347
 348         if (wsi->socket_is_permanently_unusable)
 349                 return 0;
 350
 351         pt = &wsi->context->pt[(int)wsi->tsi];
 352         lws_stats_atomic_bump(wsi->context, pt, LWSSTATS_C_WRITEABLE_CB_REQ, 1);
 353 #if defined(LWS_WITH_STATS)
 354         if (!wsi->active_writable_req_us) {
 355                 wsi->active_writable_req_us = time_in_microseconds();
 356                 lws_stats_atomic_bump(wsi->context, pt, LWSSTATS_C_WRITEABLE_CB_EFF_REQ, 1);
 357         }
 358 #endif
 359
 360 #ifdef LWS_USE_HTTP2
 361         lwsl_info("%s: %p\n", __func__, wsi);
 362
 363         if (wsi->mode != LWSCM_HTTP2_SERVING)
 364                 goto network_sock;
 365
 366         if (wsi->u.http2.requested_POLLOUT) {
 367                 lwsl_info("already pending writable\n");
 368                 return 1;
 369         }
 370
 371         if (wsi->u.http2.tx_credit <= 0) {
 372                 /*
 373                  * other side is not able to cope with us sending
 374                  * anything so no matter if we have POLLOUT on our side.
 375                  *
 376                  * Delay waiting for our POLLOUT until peer indicates he has
 377                  * space for more using tx window command in http2 layer
 378                  */
 379                 lwsl_info("%s: %p: waiting_tx_credit (%d)\n", __func__, wsi,
 380                           wsi->u.http2.tx_credit);
 381                 wsi->u.http2.waiting_tx_credit = 1;
 382                 return 0;
 383         }
 384
 385         network_wsi = lws_http2_get_network_wsi(wsi);
 386         already = network_wsi->u.http2.requested_POLLOUT;
 387
 388         /* mark everybody above him as requesting pollout */
 389
 390         wsi2 = wsi;
 391         while (wsi2) {
 392                 wsi2->u.http2.requested_POLLOUT = 1;
 393                 lwsl_info("mark %p pending writable\n", wsi2);
 394                 wsi2 = wsi2->u.http2.parent_wsi;
 395         }
 396
 397         /* for network action, act only on the network wsi */
 398
 399         wsi = network_wsi;
 400         if (already)
 401                 return 1;
 402 network_sock:
 403 #endif
 404
 405         if (lws_ext_cb_active(wsi, LWS_EXT_CB_REQUEST_ON_WRITEABLE, NULL, 0))
 406                 return 1;
 407
 408         if (wsi->position_in_fds_table < 0) {
 409                 lwsl_err("%s: failed to find socket %d\n", __func__, wsi->desc.sockfd);
 410                 return -1;
 411         }
 412
 413         if (lws_change_pollfd(wsi, 0, LWS_POLLOUT))
 414                 return -1;
 415
 416         return 1;
 417 }
 418
 419 /*
 420  * stitch protocol choice into the vh protocol linked list
 421  * We always insert ourselves at the start of the list
 422  *
 423  * X <-> B
 424  * X <-> pAn <-> pB
 425  *
 426  * Illegal to attach more than once without detach inbetween
 427  */
 428 void
 429 lws_same_vh_protocol_insert(struct lws *wsi, int n)
 430 {
 431         //lwsl_err("%s: pre insert vhost start wsi %p, that wsi prev == %p\n",
 432         //              __func__,
 433         //              wsi->vhost->same_vh_protocol_list[n],
 434         //              wsi->same_vh_protocol_prev);
 435
 436         if (wsi->same_vh_protocol_prev || wsi->same_vh_protocol_next) {
 437                 lwsl_err("Attempted to attach wsi twice to same vh prot\n");
 438                 assert(0);
 439         }
 440
 441         wsi->same_vh_protocol_prev = /* guy who points to us */
 442                 &wsi->vhost->same_vh_protocol_list[n];
 443         wsi->same_vh_protocol_next = /* old first guy is our next */
 444                         wsi->vhost->same_vh_protocol_list[n];
 445         /* we become the new first guy */
 446         wsi->vhost->same_vh_protocol_list[n] = wsi;
 447
 448         if (wsi->same_vh_protocol_next)
 449                 /* old first guy points back to us now */
 450                 wsi->same_vh_protocol_next->same_vh_protocol_prev =
 451                                 &wsi->same_vh_protocol_next;
 452 }
 453
 454 void
 455 lws_same_vh_protocol_remove(struct lws *wsi)
 456 {
 457         /*
 458          * detach ourselves from vh protocol list if we're on one
 459          * A -> B -> C
 460          * A -> C , or, B -> C, or A -> B
 461          *
 462          * OK to call on already-detached wsi
 463          */
 464         lwsl_info("%s: removing same prot wsi %p\n", __func__, wsi);
 465
 466         if (wsi->same_vh_protocol_prev) {
 467                 assert (*(wsi->same_vh_protocol_prev) == wsi);
 468                 lwsl_info("have prev %p, setting him to our next %p\n",
 469                          wsi->same_vh_protocol_prev,
 470                          wsi->same_vh_protocol_next);
 471
 472                 /* guy who pointed to us should point to our next */
 473                 *(wsi->same_vh_protocol_prev) = wsi->same_vh_protocol_next;
 474         }
 475
 476         /* our next should point back to our prev */
 477         if (wsi->same_vh_protocol_next) {
 478                 wsi->same_vh_protocol_next->same_vh_protocol_prev =
 479                                 wsi->same_vh_protocol_prev;
 480         }
 481
 482         wsi->same_vh_protocol_prev = NULL;
 483         wsi->same_vh_protocol_next = NULL;
 484 }
 485
 486
 487 LWS_VISIBLE int
 488 lws_callback_on_writable_all_protocol_vhost(const struct lws_vhost *vhost,
 489                                       const struct lws_protocols *protocol)
 490 {
 491         struct lws *wsi;
 492
 493         if (protocol < vhost->protocols ||
 494             protocol >= (vhost->protocols + vhost->count_protocols)) {
 495
 496                 lwsl_err("%s: protocol %p is not from vhost %p (%p - %p)\n",
 497                         __func__, protocol, vhost->protocols, vhost,
 498                         (vhost->protocols + vhost->count_protocols));
 499
 500                 return -1;
 501         }
 502
 503         wsi = vhost->same_vh_protocol_list[protocol - vhost->protocols];
 504         //lwsl_notice("%s: protocol %p, start wsi %p\n", __func__, protocol, wsi);
 505         while (wsi) {
 506                 //lwsl_notice("%s: protocol %p, this wsi %p (wsi->protocol=%p)\n",
 507                 //              __func__, protocol, wsi, wsi->protocol);
 508                 assert(wsi->protocol == protocol);
 509                 assert(*wsi->same_vh_protocol_prev == wsi);
 510                 if (wsi->same_vh_protocol_next) {
 511                 //      lwsl_err("my next says %p\n", wsi->same_vh_protocol_next);
 512                 //      lwsl_err("my next's prev says %p\n",
 513                 //              wsi->same_vh_protocol_next->same_vh_protocol_prev);
 514                         assert(wsi->same_vh_protocol_next->same_vh_protocol_prev == &wsi->same_vh_protocol_next);
 515                 }
 516                 //lwsl_notice("  apv: %p\n", wsi);
 517                 lws_callback_on_writable(wsi);
 518                 wsi = wsi->same_vh_protocol_next;
 519         }
 520
 521         return 0;
 522 }
 523
 524 LWS_VISIBLE int
 525 lws_callback_on_writable_all_protocol(const struct lws_context *context,
 526                                       const struct lws_protocols *protocol)
 527 {
 528         struct lws_vhost *vhost = context->vhost_list;
 529         int n;
 530
 531         while (vhost) {
 532                 for (n = 0; n < vhost->count_protocols; n++)
 533                         if (protocol->callback ==
 534                             vhost->protocols[n].callback &&
 535                             !strcmp(protocol->name, vhost->protocols[n].name))
 536                                 break;
 537                 if (n != vhost->count_protocols)
 538                         lws_callback_on_writable_all_protocol_vhost(
 539                                 vhost, &vhost->protocols[n]);
 540
 541                 vhost = vhost->vhost_next;
 542         }
 543
 544         return 0;
 545 }