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

   1 /*
   2     event.c -- I/O, timeout and signal event handling
   3     Copyright (C) 2012-2013 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
  22 #include "dropin.h"
  23 #include "event.h"
  24 #include "net.h"
  25 #include "utils.h"
  26 #include "xalloc.h"
  27
  28 struct timeval now;
  29
  30 #ifndef HAVE_MINGW
  31 static fd_set readfds;
  32 static fd_set writefds;
  33 #else
  34 static const long READ_EVENTS = FD_READ | FD_ACCEPT | FD_CLOSE;
  35 static const long WRITE_EVENTS = FD_WRITE | FD_CONNECT;
  36 static DWORD event_count = 0;
  37 #endif
  38 static bool running;
  39
  40 static int io_compare(const io_t *a, const io_t *b) {
  41 #ifndef HAVE_MINGW
  42         return a->fd - b->fd;
  43 #else
  44         return a->event - b->event;
  45 #endif
  46 }
  47
  48 static int timeout_compare(const timeout_t *a, const timeout_t *b) {
  49         struct timeval diff;
  50         timersub(&a->tv, &b->tv, &diff);
  51         if(diff.tv_sec < 0)
  52                 return -1;
  53         if(diff.tv_sec > 0)
  54                 return 1;
  55         if(diff.tv_usec < 0)
  56                 return -1;
  57         if(diff.tv_usec > 0)
  58                 return 1;
  59         if(a < b)
  60                 return -1;
  61         if(a > b)
  62                 return 1;
  63         return 0;
  64 }
  65
  66 static splay_tree_t io_tree = {.compare = (splay_compare_t)io_compare};
  67 static splay_tree_t timeout_tree = {.compare = (splay_compare_t)timeout_compare};
  68
  69 void io_add(io_t *io, io_cb_t cb, void *data, int fd, int flags) {
  70         if(io->cb)
  71                 return;
  72
  73         io->fd = fd;
  74 #ifdef HAVE_MINGW
  75         if (io->fd != -1) {
  76                 io->event = WSACreateEvent();
  77                 if (io->event == WSA_INVALID_EVENT)
  78                         abort();
  79         }
  80         event_count++;
  81 #endif
  82         io->cb = cb;
  83         io->data = data;
  84         io->node.data = io;
  85
  86         io_set(io, flags);
  87
  88         if(!splay_insert_node(&io_tree, &io->node))
  89                 abort();
  90 }
  91
  92 #ifdef HAVE_MINGW
  93 void io_add_event(io_t *io, io_cb_t cb, void *data, WSAEVENT event) {
  94         io->event = event;
  95         io_add(io, cb, data, -1, 0);
  96 }
  97 #endif
  98
  99 void io_set(io_t *io, int flags) {
 100         if (flags == io->flags)
 101                 return;
 102         io->flags = flags;
 103         if (io->fd == -1)
 104                 return;
 105
 106 #ifndef HAVE_MINGW
 107         if(flags & IO_READ)
 108                 FD_SET(io->fd, &readfds);
 109         else
 110                 FD_CLR(io->fd, &readfds);
 111
 112         if(flags & IO_WRITE)
 113                 FD_SET(io->fd, &writefds);
 114         else
 115                 FD_CLR(io->fd, &writefds);
 116 #else
 117         long events = 0;
 118         if (flags & IO_WRITE)
 119                 events |= WRITE_EVENTS;
 120         if (flags & IO_READ)
 121                 events |= READ_EVENTS;
 122         if (WSAEventSelect(io->fd, io->event, events) != 0)
 123                 abort();
 124 #endif
 125 }
 126
 127 void io_del(io_t *io) {
 128         if(!io->cb)
 129                 return;
 130
 131         io_set(io, 0);
 132 #ifdef HAVE_MINGW
 133         if (io->fd != -1 && WSACloseEvent(io->event) == FALSE)
 134                 abort();
 135         event_count--;
 136 #endif
 137
 138         splay_unlink_node(&io_tree, &io->node);
 139         io->cb = NULL;
 140 }
 141
 142 void timeout_add(timeout_t *timeout, timeout_cb_t cb, void *data, struct timeval *tv) {
 143         timeout->cb = cb;
 144         timeout->data = data;
 145         timeout->node.data = timeout;
 146
 147         timeout_set(timeout, tv);
 148 }
 149
 150 void timeout_set(timeout_t *timeout, struct timeval *tv) {
 151         if(timerisset(&timeout->tv))
 152                 splay_unlink_node(&timeout_tree, &timeout->node);
 153
 154         if(!now.tv_sec)
 155                 gettimeofday(&now, NULL);
 156
 157         timeradd(&now, tv, &timeout->tv);
 158
 159         if(!splay_insert_node(&timeout_tree, &timeout->node))
 160                 abort();
 161 }
 162
 163 void timeout_del(timeout_t *timeout) {
 164         if(!timeout->cb)
 165                 return;
 166
 167         splay_unlink_node(&timeout_tree, &timeout->node);
 168         timeout->cb = 0;
 169         timeout->tv = (struct timeval){0, 0};
 170 }
 171
 172 #ifndef HAVE_MINGW
 173 static int signal_compare(const signal_t *a, const signal_t *b) {
 174         return a->signum - b->signum;
 175 }
 176
 177 static io_t signalio;
 178 static int pipefd[2] = {-1, -1};
 179 static splay_tree_t signal_tree = {.compare = (splay_compare_t)signal_compare};
 180
 181 static void signal_handler(int signum) {
 182         unsigned char num = signum;
 183         write(pipefd[1], &num, 1);
 184 }
 185
 186 static void signalio_handler(void *data, int flags) {
 187         unsigned char signum;
 188         if(read(pipefd[0], &signum, 1) != 1)
 189                 return;
 190
 191         signal_t *sig = splay_search(&signal_tree, &((signal_t){.signum = signum}));
 192         if(sig)
 193                 sig->cb(sig->data);
 194 }
 195
 196 static void pipe_init(void) {
 197         if(!pipe(pipefd))
 198                 io_add(&signalio, signalio_handler, NULL, pipefd[0], IO_READ);
 199 }
 200
 201 void signal_add(signal_t *sig, signal_cb_t cb, void *data, int signum) {
 202         if(sig->cb)
 203                 return;
 204
 205         sig->cb = cb;
 206         sig->data = data;
 207         sig->signum = signum;
 208         sig->node.data = sig;
 209
 210         if(pipefd[0] == -1)
 211                 pipe_init();
 212
 213         signal(sig->signum, signal_handler);
 214
 215         if(!splay_insert_node(&signal_tree, &sig->node))
 216                 abort();
 217 }
 218
 219 void signal_del(signal_t *sig) {
 220         if(!sig->cb)
 221                 return;
 222
 223         signal(sig->signum, SIG_DFL);
 224
 225         splay_unlink_node(&signal_tree, &sig->node);
 226         sig->cb = NULL;
 227 }
 228 #endif
 229
 230 static struct timeval * get_time_remaining(struct timeval *diff) {
 231         gettimeofday(&now, NULL);
 232         struct timeval *tv = NULL;
 233
 234         while(timeout_tree.head) {
 235                 timeout_t *timeout = timeout_tree.head->data;
 236                 timersub(&timeout->tv, &now, diff);
 237
 238                 if(diff->tv_sec < 0) {
 239                         timeout->cb(timeout->data);
 240                         if(timercmp(&timeout->tv, &now, <))
 241                                 timeout_del(timeout);
 242                 } else {
 243                         tv = diff;
 244                         break;
 245                 }
 246         }
 247
 248         return tv;
 249 }
 250
 251 bool event_loop(void) {
 252         running = true;
 253
 254 #ifndef HAVE_MINGW
 255         fd_set readable;
 256         fd_set writable;
 257
 258         while(running) {
 259                 struct timeval diff;
 260                 struct timeval *tv = get_time_remaining(&diff);
 261                 memcpy(&readable, &readfds, sizeof readable);
 262                 memcpy(&writable, &writefds, sizeof writable);
 263
 264                 int fds = 0;
 265
 266                 if(io_tree.tail) {
 267                         io_t *last = io_tree.tail->data;
 268                         fds = last->fd + 1;
 269                 }
 270
 271                 int n = select(fds, &readable, &writable, NULL, tv);
 272
 273                 if(n < 0) {
 274                         if(sockwouldblock(sockerrno))
 275                                 continue;
 276                         else
 277                                 return false;
 278                 }
 279
 280                 if(!n)
 281                         continue;
 282
 283                 for splay_each(io_t, io, &io_tree) {
 284                         if(FD_ISSET(io->fd, &writable))
 285                                 io->cb(io->data, IO_WRITE);
 286                         else if(FD_ISSET(io->fd, &readable))
 287                                 io->cb(io->data, IO_READ);
 288                         else
 289                                 continue;
 290
 291                         /*
 292                            There are scenarios in which the callback will remove another io_t from the tree
 293                            (e.g. closing a double connection). Since splay_each does not support that, we
 294                            need to exit the loop now. That's okay, since any remaining events will get picked
 295                            up by the next select() call.
 296                          */
 297                         break;
 298                 }
 299         }
 300 #else
 301         while (running) {
 302                 struct timeval diff;
 303                 struct timeval *tv = get_time_remaining(&diff);
 304                 DWORD timeout_ms = tv ? (tv->tv_sec * 1000 + tv->tv_usec / 1000 + 1) : WSA_INFINITE;
 305
 306                 if (!event_count) {
 307                         Sleep(timeout_ms);
 308                         continue;
 309                 }
 310
 311                 /*
 312                    For some reason, Microsoft decided to make the FD_WRITE event edge-triggered instead of level-triggered,
 313                    which is the opposite of what select() does. In practice, that means that if a FD_WRITE event triggers,
 314                    it will never trigger again until a send() returns EWOULDBLOCK. Since the semantics of this event loop
 315                    is that write events are level-triggered (i.e. they continue firing until the socket is full), we need
 316                    to emulate these semantics by making sure we fire each IO_WRITE that is still writeable.
 317
 318                    Note that technically FD_CLOSE has the same problem, but it's okay because user code does not rely on
 319                    this event being fired again if ignored.
 320                 */
 321                 io_t* writeable_io = NULL;
 322                 for splay_each(io_t, io, &io_tree)
 323                         if (io->flags & IO_WRITE && send(io->fd, NULL, 0, 0) == 0) {
 324                                 writeable_io = io;
 325                                 break;
 326                         }
 327                 if (writeable_io) {
 328                         writeable_io->cb(writeable_io->data, IO_WRITE);
 329                         continue;
 330                 }
 331
 332                 WSAEVENT* events = xmalloc(event_count * sizeof(*events));
 333                 DWORD event_index = 0;
 334                 for splay_each(io_t, io, &io_tree) {
 335                         events[event_index] = io->event;
 336                         event_index++;
 337                 }
 338
 339                 DWORD result = WSAWaitForMultipleEvents(event_count, events, FALSE, timeout_ms, FALSE);
 340
 341                 WSAEVENT event;
 342                 if (result >= WSA_WAIT_EVENT_0 && result < WSA_WAIT_EVENT_0 + event_count)
 343                         event = events[result - WSA_WAIT_EVENT_0];
 344                 free(events);
 345                 if (result == WSA_WAIT_TIMEOUT)
 346                         continue;
 347                 if (result < WSA_WAIT_EVENT_0 || result >= WSA_WAIT_EVENT_0 + event_count)
 348                         return false;
 349
 350                 io_t *io = splay_search(&io_tree, &((io_t){.event = event}));
 351                 if (!io)
 352                         abort();
 353
 354                 if (io->fd == -1) {
 355                         io->cb(io->data, 0);
 356                 } else {
 357                         WSANETWORKEVENTS network_events;
 358                         if (WSAEnumNetworkEvents(io->fd, io->event, &network_events) != 0)
 359                                 return false;
 360                         if (network_events.lNetworkEvents & READ_EVENTS)
 361                                 io->cb(io->data, IO_READ);
 362                         /*
 363                             The fd might be available for write too. However, if we already fired the read callback, that
 364                             callback might have deleted the io (e.g. through terminate_connection()), so we can't fire the
 365                             write callback here. Instead, we loop back and let the writable io loop above handle it.
 366                          */
 367                 }
 368         }
 369 #endif
 370
 371         return true;
 372 }
 373
 374 void event_exit(void) {
 375         running = false;
 376 }