tinc-vpn.org Git - tinc/blob - src/event.c

   1 /*
   2     event.c -- I/O, timeout and signal event handling
   3     Copyright (C) 2012-2021 Guus Sliepen <guus@tinc-vpn.org>
   4
   5     This program is free software; you can redistribute it and/or modify
   6     it under the terms of the GNU General Public License as published by
   7     the Free Software Foundation; either version 2 of the License, or
   8     (at your option) any later version.
   9
  10     This program is distributed in the hope that it will be useful,
  11     but WITHOUT ANY WARRANTY; without even the implied warranty of
  12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13     GNU General Public License for more details.
  14
  15     You should have received a copy of the GNU General Public License along
  16     with this program; if not, write to the Free Software Foundation, Inc.,
  17     51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  18 */
  19
  20 #include "system.h"
  21 #include "dropin.h"
  22
  23 #ifdef HAVE_SYS_EPOLL_H
  24 #include <sys/epoll.h>
  25 #endif
  26
  27 #include "event.h"
  28 #include "utils.h"
  29 #include "net.h"
  30
  31 struct timeval now;
  32 #ifndef HAVE_MINGW
  33
  34 #ifdef HAVE_SYS_EPOLL_H
  35 static int epollset = 0;
  36 #else
  37 static fd_set readfds;
  38 static fd_set writefds;
  39 #endif
  40
  41 #else
  42 static const long READ_EVENTS = FD_READ | FD_ACCEPT | FD_CLOSE;
  43 static const long WRITE_EVENTS = FD_WRITE | FD_CONNECT;
  44 static DWORD event_count = 0;
  45 #endif
  46 static bool running;
  47
  48 #ifdef HAVE_SYS_EPOLL_H
  49 static inline int event_epoll_init() {
  50         /* NOTE: 1024 limit is only used on ancient (pre 2.6.27) kernels.
  51                 Decent kernels will ignore this value making it unlimited.
  52                 epoll_create1 might be better, but these kernels would not be supported
  53                 in that case.
  54         */
  55         return epoll_create(1024);
  56 }
  57 #endif
  58
  59 static int io_compare(const io_t *a, const io_t *b) {
  60 #ifndef HAVE_MINGW
  61         return a->fd - b->fd;
  62 #else
  63
  64         if(a->event < b->event) {
  65                 return -1;
  66         }
  67
  68         if(a->event > b->event) {
  69                 return 1;
  70         }
  71
  72         return 0;
  73 #endif
  74 }
  75
  76 static int timeout_compare(const timeout_t *a, const timeout_t *b) {
  77         struct timeval diff;
  78         timersub(&a->tv, &b->tv, &diff);
  79
  80         if(diff.tv_sec < 0) {
  81                 return -1;
  82         }
  83
  84         if(diff.tv_sec > 0) {
  85                 return 1;
  86         }
  87
  88         if(diff.tv_usec < 0) {
  89                 return -1;
  90         }
  91
  92         if(diff.tv_usec > 0) {
  93                 return 1;
  94         }
  95
  96         if(a < b) {
  97                 return -1;
  98         }
  99
 100         if(a > b) {
 101                 return 1;
 102         }
 103
 104         return 0;
 105 }
 106
 107 static splay_tree_t io_tree = {.compare = (splay_compare_t)io_compare};
 108 static splay_tree_t timeout_tree = {.compare = (splay_compare_t)timeout_compare};
 109
 110 void io_add(io_t *io, io_cb_t cb, void *data, int fd, int flags) {
 111         if(io->cb) {
 112                 return;
 113         }
 114
 115         io->fd = fd;
 116 #ifdef HAVE_MINGW
 117
 118         if(io->fd != -1) {
 119                 io->event = WSACreateEvent();
 120
 121                 if(io->event == WSA_INVALID_EVENT) {
 122                         abort();
 123                 }
 124         }
 125
 126         event_count++;
 127 #endif
 128         io->cb = cb;
 129         io->data = data;
 130         io->node.data = io;
 131
 132         io_set(io, flags);
 133
 134 #ifndef HAVE_SYS_EPOLL_H
 135
 136         if(!splay_insert_node(&io_tree, &io->node)) {
 137                 abort();
 138         }
 139
 140 #endif
 141 }
 142
 143 #ifdef HAVE_MINGW
 144 void io_add_event(io_t *io, io_cb_t cb, void *data, WSAEVENT event) {
 145         io->event = event;
 146         io_add(io, cb, data, -1, 0);
 147 }
 148 #endif
 149
 150 void io_set(io_t *io, int flags) {
 151 #ifdef HAVE_SYS_EPOLL_H
 152
 153         if(!epollset) {
 154                 epollset = event_epoll_init();
 155         }
 156
 157 #endif
 158
 159         if(flags == io->flags) {
 160                 return;
 161         }
 162
 163         io->flags = flags;
 164
 165         if(io->fd == -1) {
 166                 return;
 167         }
 168
 169 #ifndef HAVE_MINGW
 170 #ifdef HAVE_SYS_EPOLL_H
 171         epoll_ctl(epollset, EPOLL_CTL_DEL, io->fd, NULL);
 172
 173         struct epoll_event ev = {
 174                 .events = 0,
 175                 .data.ptr = io,
 176         };
 177
 178         if(flags & IO_READ) {
 179                 ev.events |= EPOLLIN;
 180         }
 181
 182         if(flags & IO_WRITE) {
 183                 ev.events |= EPOLLOUT;
 184         } else if(ev.events == 0) {
 185                 io_tree.generation++;
 186                 return;
 187         }
 188
 189         if(epoll_ctl(epollset, EPOLL_CTL_ADD, io->fd, &ev) < 0) {
 190                 perror("epoll_ctl_add");
 191         }
 192
 193 #else
 194
 195         if(flags & IO_READ) {
 196                 FD_SET(io->fd, &readfds);
 197         } else {
 198                 FD_CLR(io->fd, &readfds);
 199         }
 200
 201         if(flags & IO_WRITE) {
 202                 FD_SET(io->fd, &writefds);
 203         } else {
 204                 FD_CLR(io->fd, &writefds);
 205         }
 206
 207 #endif
 208 #else
 209         long events = 0;
 210
 211         if(flags & IO_WRITE) {
 212                 events |= WRITE_EVENTS;
 213         }
 214
 215         if(flags & IO_READ) {
 216                 events |= READ_EVENTS;
 217         }
 218
 219         if(WSAEventSelect(io->fd, io->event, events) != 0) {
 220                 abort();
 221         }
 222
 223 #endif
 224 }
 225
 226 void io_del(io_t *io) {
 227         if(!io->cb) {
 228                 return;
 229         }
 230
 231         io_set(io, 0);
 232 #ifdef HAVE_MINGW
 233
 234         if(io->fd != -1 && WSACloseEvent(io->event) == FALSE) {
 235                 abort();
 236         }
 237
 238         event_count--;
 239 #endif
 240
 241 #ifndef HAVE_SYS_EPOLL_H
 242         splay_unlink_node(&io_tree, &io->node);
 243 #endif
 244         io->cb = NULL;
 245 }
 246
 247 void timeout_add(timeout_t *timeout, timeout_cb_t cb, void *data, struct timeval *tv) {
 248         timeout->cb = cb;
 249         timeout->data = data;
 250         timeout->node.data = timeout;
 251
 252         timeout_set(timeout, tv);
 253 }
 254
 255 void timeout_set(timeout_t *timeout, struct timeval *tv) {
 256         if(timerisset(&timeout->tv)) {
 257                 splay_unlink_node(&timeout_tree, &timeout->node);
 258         }
 259
 260         if(!now.tv_sec) {
 261                 gettimeofday(&now, NULL);
 262         }
 263
 264         timeradd(&now, tv, &timeout->tv);
 265
 266         if(!splay_insert_node(&timeout_tree, &timeout->node)) {
 267                 abort();
 268         }
 269 }
 270
 271 void timeout_del(timeout_t *timeout) {
 272         if(!timeout->cb) {
 273                 return;
 274         }
 275
 276         splay_unlink_node(&timeout_tree, &timeout->node);
 277         timeout->cb = 0;
 278         timeout->tv = (struct timeval) {
 279                 0, 0
 280         };
 281 }
 282
 283 #ifndef HAVE_MINGW
 284
 285 // From Matz's Ruby
 286 #ifndef NSIG
 287 # define NSIG (_SIGMAX + 1)      /* For QNX */
 288 #endif
 289
 290
 291 static io_t signalio;
 292 static int pipefd[2] = {-1, -1};
 293 static signal_t *signal_handle[NSIG + 1] = {};
 294
 295 static void signal_handler(int signum) {
 296         unsigned char num = signum;
 297         write(pipefd[1], &num, 1);
 298 }
 299
 300 static void signalio_handler(void *data, int flags) {
 301         (void)data;
 302         (void)flags;
 303         unsigned char signum;
 304
 305         if(read(pipefd[0], &signum, 1) != 1) {
 306                 return;
 307         }
 308
 309         signal_t *sig = signal_handle[signum];
 310
 311         if(sig) {
 312                 sig->cb(sig->data);
 313         }
 314 }
 315
 316 static void pipe_init(void) {
 317         if(!pipe(pipefd)) {
 318                 io_add(&signalio, signalio_handler, NULL, pipefd[0], IO_READ);
 319         }
 320 }
 321
 322 void signal_add(signal_t *sig, signal_cb_t cb, void *data, int signum) {
 323         if(sig->cb) {
 324                 return;
 325         }
 326
 327         sig->signum = signum;
 328         sig->cb = cb;
 329         sig->data = data;
 330
 331         if(pipefd[0] == -1) {
 332                 pipe_init();
 333         }
 334
 335         signal(signum, signal_handler);
 336
 337         signal_handle[signum] = sig;
 338 }
 339
 340 void signal_del(signal_t *sig) {
 341         if(!sig->cb) {
 342                 return;
 343         }
 344
 345         signal(sig->signum, SIG_DFL);
 346
 347         signal_handle[sig->signum] = NULL;
 348         sig->cb = NULL;
 349 }
 350 #endif
 351
 352 static struct timeval *timeout_execute(struct timeval *diff) {
 353         gettimeofday(&now, NULL);
 354         struct timeval *tv = NULL;
 355
 356         while(timeout_tree.head) {
 357                 timeout_t *timeout = timeout_tree.head->data;
 358                 timersub(&timeout->tv, &now, diff);
 359
 360                 if(diff->tv_sec < 0) {
 361                         timeout->cb(timeout->data);
 362
 363                         if(timercmp(&timeout->tv, &now, <)) {
 364                                 timeout_del(timeout);
 365                         }
 366                 } else {
 367                         tv = diff;
 368                         break;
 369                 }
 370         }
 371
 372         return tv;
 373 }
 374
 375 bool event_loop(void) {
 376         running = true;
 377
 378 #ifndef HAVE_MINGW
 379
 380 #ifdef HAVE_SYS_EPOLL_H
 381
 382         if(!epollset) {
 383                 epollset = event_epoll_init();
 384         }
 385
 386 #else
 387         fd_set readable;
 388         fd_set writable;
 389 #endif
 390
 391         while(running) {
 392                 struct timeval diff;
 393                 struct timeval *tv = timeout_execute(&diff);
 394 #ifndef HAVE_SYS_EPOLL_H
 395                 memcpy(&readable, &readfds, sizeof(readable));
 396                 memcpy(&writable, &writefds, sizeof(writable));
 397 #endif
 398
 399
 400 #ifdef HAVE_SYS_EPOLL_H
 401                 struct epoll_event events[EPOLL_MAX_EVENTS_PER_LOOP];
 402                 long timeout = (tv->tv_sec * 1000) + (tv->tv_usec / 1000);
 403
 404                 if(timeout > INT_MAX) {
 405                         timeout = INT_MAX;
 406                 }
 407
 408                 int n = epoll_wait(epollset, events, EPOLL_MAX_EVENTS_PER_LOOP, (int)timeout);
 409 #else
 410                 int maxfds =  0;
 411
 412                 if(io_tree.tail) {
 413                         io_t *last = io_tree.tail->data;
 414                         maxfds = last->fd + 1;
 415                 }
 416
 417                 int n = select(maxfds, &readable, &writable, NULL, tv);
 418 #endif
 419
 420                 if(n < 0) {
 421                         if(sockwouldblock(sockerrno)) {
 422                                 continue;
 423                         } else {
 424                                 return false;
 425                         }
 426                 }
 427
 428                 if(!n) {
 429                         continue;
 430                 }
 431
 432                 unsigned int curgen = io_tree.generation;
 433
 434
 435 #ifdef HAVE_SYS_EPOLL_H
 436
 437                 for(int i = 0; i < n; i++) {
 438                         io_t *io = events[i].data.ptr;
 439
 440                         if(events[i].events & EPOLLOUT && io->flags & IO_WRITE) {
 441                                 io->cb(io->data, IO_WRITE);
 442                         }
 443
 444                         if(curgen != io_tree.generation) {
 445                                 break;
 446                         }
 447
 448                         if(events[i].events & EPOLLIN && io->flags & IO_READ) {
 449                                 io->cb(io->data, IO_READ);
 450                         }
 451
 452                         if(curgen != io_tree.generation) {
 453                                 break;
 454                         }
 455                 }
 456
 457 #else
 458
 459                 for splay_each(io_t, io, &io_tree) {
 460                         if(FD_ISSET(io->fd, &writable)) {
 461                                 io->cb(io->data, IO_WRITE);
 462                         } else if(FD_ISSET(io->fd, &readable)) {
 463                                 io->cb(io->data, IO_READ);
 464                         } else {
 465                                 continue;
 466                         }
 467
 468                         /*
 469                                 There are scenarios in which the callback will remove another io_t from the tree
 470                                 (e.g. closing a double connection). Since splay_each does not support that, we
 471                                 need to exit the loop if that happens. That's okay, since any remaining events will
 472                                 get picked up by the next select() call.
 473                         */
 474                         if(curgen != io_tree.generation) {
 475                                 break;
 476                         }
 477                 }
 478
 479 #endif
 480         }
 481
 482 #else
 483
 484         while(running) {
 485                 struct timeval diff;
 486                 struct timeval *tv = timeout_execute(&diff);
 487                 DWORD timeout_ms = tv ? (DWORD)(tv->tv_sec * 1000 + tv->tv_usec / 1000 + 1) : WSA_INFINITE;
 488
 489                 if(!event_count) {
 490                         Sleep(timeout_ms);
 491                         continue;
 492                 }
 493
 494                 /*
 495                    For some reason, Microsoft decided to make the FD_WRITE event edge-triggered instead of level-triggered,
 496                    which is the opposite of what select() does. In practice, that means that if a FD_WRITE event triggers,
 497                    it will never trigger again until a send() returns EWOULDBLOCK. Since the semantics of this event loop
 498                    is that write events are level-triggered (i.e. they continue firing until the socket is full), we need
 499                    to emulate these semantics by making sure we fire each IO_WRITE that is still writeable.
 500
 501                    Note that technically FD_CLOSE has the same problem, but it's okay because user code does not rely on
 502                    this event being fired again if ignored.
 503                 */
 504                 unsigned int curgen = io_tree.generation;
 505
 506                 for splay_each(io_t, io, &io_tree) {
 507                         if(io->flags & IO_WRITE && send(io->fd, NULL, 0, 0) == 0) {
 508                                 io->cb(io->data, IO_WRITE);
 509
 510                                 if(curgen != io_tree.generation) {
 511                                         break;
 512                                 }
 513                         }
 514                 }
 515
 516                 if(event_count > WSA_MAXIMUM_WAIT_EVENTS) {
 517                         WSASetLastError(WSA_INVALID_PARAMETER);
 518                         return(false);
 519                 }
 520
 521                 WSAEVENT events[WSA_MAXIMUM_WAIT_EVENTS];
 522                 io_t *io_map[WSA_MAXIMUM_WAIT_EVENTS];
 523                 DWORD event_index = 0;
 524
 525                 for splay_each(io_t, io, &io_tree) {
 526                         events[event_index] = io->event;
 527                         io_map[event_index] = io;
 528                         event_index++;
 529                 }
 530
 531                 /*
 532                  * If the generation number changes due to event addition
 533                  * or removal by a callback we restart the loop.
 534                  */
 535                 curgen = io_tree.generation;
 536
 537                 for(DWORD event_offset = 0; event_offset < event_count;) {
 538                         DWORD result = WSAWaitForMultipleEvents(event_count - event_offset, &events[event_offset], FALSE, timeout_ms, FALSE);
 539
 540                         if(result == WSA_WAIT_TIMEOUT) {
 541                                 break;
 542                         }
 543
 544                         if(result < WSA_WAIT_EVENT_0 || result >= WSA_WAIT_EVENT_0 + event_count - event_offset) {
 545                                 return false;
 546                         }
 547
 548                         /* Look up io in the map by index. */
 549                         event_index = result - WSA_WAIT_EVENT_0 + event_offset;
 550                         io_t *io = io_map[event_index];
 551
 552                         if(io->fd == -1) {
 553                                 io->cb(io->data, 0);
 554
 555                                 if(curgen != io_tree.generation) {
 556                                         break;
 557                                 }
 558                         } else {
 559                                 WSANETWORKEVENTS network_events;
 560
 561                                 if(WSAEnumNetworkEvents(io->fd, io->event, &network_events) != 0) {
 562                                         return(false);
 563                                 }
 564
 565                                 if(network_events.lNetworkEvents & READ_EVENTS) {
 566                                         io->cb(io->data, IO_READ);
 567
 568                                         if(curgen != io_tree.generation) {
 569                                                 break;
 570                                         }
 571                                 }
 572
 573                                 /*
 574                                     The fd might be available for write too. However, if we already fired the read callback, that
 575                                     callback might have deleted the io (e.g. through terminate_connection()), so we can't fire the
 576                                     write callback here. Instead, we loop back and let the writable io loop above handle it.
 577                                  */
 578                         }
 579
 580                         /* Continue checking the rest of the events. */
 581                         event_offset = event_index + 1;
 582
 583                         /* Just poll the next time through. */
 584                         timeout_ms = 0;
 585                 }
 586         }
 587
 588 #endif
 589
 590         return true;
 591 }
 592
 593 void event_exit(void) {
 594         running = false;
 595 }