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 volatile 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         io->event = WSACreateEvent();
  76         if (io->event == WSA_INVALID_EVENT)
  77                 abort();
  78         event_count++;
  79 #endif
  80         io->cb = cb;
  81         io->data = data;
  82         io->node.data = io;
  83
  84         io_set(io, flags);
  85
  86         if(!splay_insert_node(&io_tree, &io->node))
  87                 abort();
  88 }
  89
  90 void io_set(io_t *io, int flags) {
  91         if (flags == io->flags)
  92                 return;
  93         io->flags = flags;
  94
  95 #ifndef HAVE_MINGW
  96         if(flags & IO_READ)
  97                 FD_SET(io->fd, &readfds);
  98         else
  99                 FD_CLR(io->fd, &readfds);
 100
 101         if(flags & IO_WRITE)
 102                 FD_SET(io->fd, &writefds);
 103         else
 104                 FD_CLR(io->fd, &writefds);
 105 #else
 106         long events = 0;
 107         if (flags & IO_WRITE)
 108                 events |= WRITE_EVENTS;
 109         if (flags & IO_READ)
 110                 events |= READ_EVENTS;
 111         if (WSAEventSelect(io->fd, io->event, events) != 0)
 112                 abort();
 113 #endif
 114 }
 115
 116 void io_del(io_t *io) {
 117         if(!io->cb)
 118                 return;
 119
 120         io_set(io, 0);
 121 #ifdef HAVE_MINGW
 122         if (WSACloseEvent(io->event) == FALSE)
 123                 abort();
 124         event_count--;
 125 #endif
 126
 127         splay_unlink_node(&io_tree, &io->node);
 128         io->cb = NULL;
 129 }
 130
 131 void timeout_add(timeout_t *timeout, timeout_cb_t cb, void *data, struct timeval *tv) {
 132         timeout->cb = cb;
 133         timeout->data = data;
 134         timeout->node.data = timeout;
 135
 136         timeout_set(timeout, tv);
 137 }
 138
 139 void timeout_set(timeout_t *timeout, struct timeval *tv) {
 140         if(timerisset(&timeout->tv))
 141                 splay_unlink_node(&timeout_tree, &timeout->node);
 142
 143         if(!now.tv_sec)
 144                 gettimeofday(&now, NULL);
 145
 146         timeradd(&now, tv, &timeout->tv);
 147
 148         if(!splay_insert_node(&timeout_tree, &timeout->node))
 149                 abort();
 150 }
 151
 152 void timeout_del(timeout_t *timeout) {
 153         if(!timeout->cb)
 154                 return;
 155
 156         splay_unlink_node(&timeout_tree, &timeout->node);
 157         timeout->cb = 0;
 158         timeout->tv = (struct timeval){0, 0};
 159 }
 160
 161 #ifndef HAVE_MINGW
 162 static int signal_compare(const signal_t *a, const signal_t *b) {
 163         return a->signum - b->signum;
 164 }
 165
 166 static io_t signalio;
 167 static int pipefd[2] = {-1, -1};
 168 static splay_tree_t signal_tree = {.compare = (splay_compare_t)signal_compare};
 169
 170 static void signal_handler(int signum) {
 171         unsigned char num = signum;
 172         write(pipefd[1], &num, 1);
 173 }
 174
 175 static void signalio_handler(void *data, int flags) {
 176         unsigned char signum;
 177         if(read(pipefd[0], &signum, 1) != 1)
 178                 return;
 179
 180         signal_t *sig = splay_search(&signal_tree, &((signal_t){.signum = signum}));
 181         if(sig)
 182                 sig->cb(sig->data);
 183 }
 184
 185 static void pipe_init(void) {
 186         if(!pipe(pipefd))
 187                 io_add(&signalio, signalio_handler, NULL, pipefd[0], IO_READ);
 188 }
 189
 190 void signal_add(signal_t *sig, signal_cb_t cb, void *data, int signum) {
 191         if(sig->cb)
 192                 return;
 193
 194         sig->cb = cb;
 195         sig->data = data;
 196         sig->signum = signum;
 197         sig->node.data = sig;
 198
 199         if(pipefd[0] == -1)
 200                 pipe_init();
 201
 202         signal(sig->signum, signal_handler);
 203
 204         if(!splay_insert_node(&signal_tree, &sig->node))
 205                 abort();
 206 }
 207
 208 void signal_del(signal_t *sig) {
 209         if(!sig->cb)
 210                 return;
 211
 212         signal(sig->signum, SIG_DFL);
 213
 214         splay_unlink_node(&signal_tree, &sig->node);
 215         sig->cb = NULL;
 216 }
 217 #endif
 218
 219 static struct timeval * get_time_remaining(struct timeval *diff) {
 220         gettimeofday(&now, NULL);
 221         struct timeval *tv = NULL;
 222
 223         while(timeout_tree.head) {
 224                 timeout_t *timeout = timeout_tree.head->data;
 225                 timersub(&timeout->tv, &now, diff);
 226
 227                 if(diff->tv_sec < 0) {
 228                         timeout->cb(timeout->data);
 229                         if(timercmp(&timeout->tv, &now, <))
 230                                 timeout_del(timeout);
 231                 } else {
 232                         tv = diff;
 233                         break;
 234                 }
 235         }
 236
 237         return tv;
 238 }
 239
 240 bool event_loop(void) {
 241         running = true;
 242
 243 #ifndef HAVE_MINGW
 244         fd_set readable;
 245         fd_set writable;
 246
 247         while(running) {
 248                 memcpy(&readable, &readfds, sizeof readable);
 249                 memcpy(&writable, &writefds, sizeof writable);
 250                 struct timeval diff;
 251                 struct timeval *tv = get_time_remaining(&diff);
 252
 253                 int fds = 0;
 254
 255                 if(io_tree.tail) {
 256                         io_t *last = io_tree.tail->data;
 257                         fds = last->fd + 1;
 258                 }
 259
 260                 int n = select(fds, &readable, &writable, NULL, tv);
 261
 262                 if(n < 0) {
 263                         if(sockwouldblock(sockerrno))
 264                                 continue;
 265                         else
 266                                 return false;
 267                 }
 268
 269                 if(!n)
 270                         continue;
 271
 272                 for splay_each(io_t, io, &io_tree) {
 273                         if(FD_ISSET(io->fd, &writable))
 274                                 io->cb(io->data, IO_WRITE);
 275                         else if(FD_ISSET(io->fd, &readable))
 276                                 io->cb(io->data, IO_READ);
 277                 }
 278         }
 279 #else
 280         while (running) {
 281                 struct timeval diff;
 282                 struct timeval *tv = get_time_remaining(&diff);
 283                 DWORD timeout_ms = tv ? (tv->tv_sec * 1000 + tv->tv_usec / 1000 + 1) : WSA_INFINITE;
 284
 285                 if (!event_count) {
 286                         LeaveCriticalSection(&mutex);
 287                         Sleep(timeout_ms);
 288                         EnterCriticalSection(&mutex);
 289                         continue;
 290                 }
 291
 292                 /*
 293                    For some reason, Microsoft decided to make the FD_WRITE event edge-triggered instead of level-triggered,
 294                    which is the opposite of what select() does. In practice, that means that if a FD_WRITE event triggers,
 295                    it will never trigger again until a send() returns EWOULDBLOCK. Since the semantics of this event loop
 296                    is that write events are level-triggered (i.e. they continue firing until the socket is full), we need
 297                    to emulate these semantics by making sure we fire each IO_WRITE that is still writeable.
 298
 299                    Note that technically FD_CLOSE has the same problem, but it's okay because user code does not rely on
 300                    this event being fired again if ignored.
 301                 */
 302                 io_t* writeable_io = NULL;
 303                 for splay_each(io_t, io, &io_tree)
 304                         if (io->flags & IO_WRITE && send(io->fd, NULL, 0, 0) == 0) {
 305                                 writeable_io = io;
 306                                 break;
 307                         }
 308                 if (writeable_io) {
 309                         writeable_io->cb(writeable_io->data, IO_WRITE);
 310                         continue;
 311                 }
 312
 313                 WSAEVENT* events = xmalloc(event_count * sizeof(*events));
 314                 DWORD event_index = 0;
 315                 for splay_each(io_t, io, &io_tree) {
 316                         events[event_index] = io->event;
 317                         event_index++;
 318                 }
 319
 320                 LeaveCriticalSection(&mutex);
 321                 DWORD result = WSAWaitForMultipleEvents(event_count, events, FALSE, timeout_ms, FALSE);
 322                 EnterCriticalSection(&mutex);
 323
 324                 WSAEVENT event;
 325                 if (result >= WSA_WAIT_EVENT_0 && result < WSA_WAIT_EVENT_0 + event_count)
 326                         event = events[result - WSA_WAIT_EVENT_0];
 327                 free(events);
 328                 if (result == WSA_WAIT_TIMEOUT)
 329                         continue;
 330                 if (result < WSA_WAIT_EVENT_0 || result >= WSA_WAIT_EVENT_0 + event_count)
 331                         return false;
 332
 333                 io_t *io = splay_search(&io_tree, &((io_t){.event = event}));
 334                 if (!io)
 335                         abort();
 336
 337                 WSANETWORKEVENTS network_events;
 338                 if (WSAEnumNetworkEvents(io->fd, io->event, &network_events) != 0)
 339                         return false;
 340                 if (network_events.lNetworkEvents & WRITE_EVENTS)
 341                         io->cb(io->data, IO_WRITE);
 342                 if (network_events.lNetworkEvents & READ_EVENTS)
 343                         io->cb(io->data, IO_READ);
 344         }
 345 #endif
 346
 347         return true;
 348 }
 349
 350 void event_flush_output(void) {
 351         for splay_each(io_t, io, &io_tree)
 352                 if(io->flags & IO_WRITE)
 353                         io->cb(io->data, IO_WRITE);
 354 }
 355
 356 void event_exit(void) {
 357         running = false;
 358 }