ircd/engine_poll.c

   1 /*
   2  * IRC - Internet Relay Chat, ircd/engine_poll.c
   3  * Copyright (C) 2001 Kevin L. Mitchell <klmitch@mit.edu>
   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 1, or (at your option)
   8  * 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
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  18  */
  19 /** @file
  20  * @brief POSIX poll() event engine.
  21  * @version $Id: engine_poll.c,v 1.10 2004/12/11 05:13:44 klmitch Exp $
  22  */
  23 #include "config.h"
  24
  25 #include "ircd_events.h"
  26
  27 #include "ircd.h"
  28 #include "ircd_alloc.h"
  29 #include "ircd_log.h"
  30 #include "s_debug.h"
  31
  32 /* #include <assert.h> -- Now using assert in ircd_log.h */
  33 #include <errno.h>
  34 #include <sys/poll.h>
  35 #include <sys/socket.h>
  36 #include <sys/types.h>
  37 #include <time.h>
  38 #include <unistd.h>
  39
  40 #define POLL_ERROR_THRESHOLD    20      /**< after 20 poll errors, restart */
  41 #define ERROR_EXPIRE_TIME       3600    /**< expire errors after an hour */
  42
  43 /* Figure out what bits to set for read */
  44 #if defined(POLLMSG) && defined(POLLIN) && defined(POLLRDNORM)
  45 #  define POLLREADFLAGS (POLLMSG|POLLIN|POLLRDNORM)
  46 #elif defined(POLLIN) && defined(POLLRDNORM)
  47 #  define POLLREADFLAGS (POLLIN|POLLRDNORM)
  48 #elif defined(POLLIN)
  49 #  define POLLREADFLAGS POLLIN
  50 #elif defined(POLLRDNORM)
  51 #  define POLLREADFLAGS POLLRDNORM
  52 #endif
  53
  54 /* Figure out what bits to set for write */
  55 #if defined(POLLOUT) && defined(POLLWRNORM)
  56 #  define POLLWRITEFLAGS (POLLOUT|POLLWRNORM)
  57 #elif defined(POLLOUT)
  58 #  define POLLWRITEFLAGS POLLOUT
  59 #elif defined(POLLWRNORM)
  60 #  define POLLWRITEFLAGS POLLWRNORM
  61 #endif
  62
  63 /** Array of active Socket structures, indexed by file descriptor. */
  64 static struct Socket** sockList;
  65 /** Array of poll() active elements. */
  66 static struct pollfd* pollfdList;
  67 /** Number of pollfd elements currently used. */
  68 static unsigned int poll_count;
  69 /** Maximum file descriptor supported, plus one. */
  70 static unsigned int poll_max;
  71
  72 /** Number of recent errors from poll(). */
  73 static int errors = 0;
  74 /** Periodic timer to forget errors. */
  75 static struct Timer clear_error;
  76
  77 /** Decrement the error count (once per hour).
  78  * @param[in] ev Expired timer event (ignored).
  79  */
  80 static void
  81 error_clear(struct Event* ev)
  82 {
  83   if (!--errors) /* remove timer when error count reaches 0 */
  84     timer_del(ev_timer(ev));
  85 }
  86
  87 /** Initialize the poll() engine.
  88  * @param[in] max_sockets Maximum number of file descriptors to support.
  89  * @return Non-zero on success, or zero on failure.
  90  */
  91 static int
  92 engine_init(int max_sockets)
  93 {
  94   int i;
  95
  96   /* allocate necessary memory */
  97   sockList = (struct Socket**) MyMalloc(sizeof(struct Socket*) * max_sockets);
  98   pollfdList = (struct pollfd*) MyMalloc(sizeof(struct pollfd) * max_sockets);
  99
 100   /* initialize the data */
 101   for (i = 0; i < max_sockets; i++) {
 102     sockList[i] = 0;
 103     pollfdList[i].fd = -1;
 104     pollfdList[i].events = 0;
 105     pollfdList[i].revents = 0;
 106   }
 107
 108   poll_count = 0; /* nothing in set */
 109   poll_max = max_sockets; /* number of sockets allocated */
 110
 111   return 1;
 112 }
 113
 114 /** Figure out what events go with a given state.
 115  * @param[in] state %Socket state to consider.
 116  * @param[in] events User-specified preferred event set.
 117  * @return Actual set of preferred events.
 118  */
 119 static unsigned int
 120 state_to_events(enum SocketState state, unsigned int events)
 121 {
 122   switch (state) {
 123   case SS_CONNECTING: /* connecting socket */
 124     return SOCK_EVENT_WRITABLE;
 125     break;
 126
 127   case SS_LISTENING: /* listening socket */
 128   case SS_NOTSOCK: /* our signal socket */
 129     return SOCK_EVENT_READABLE;
 130     break;
 131
 132   case SS_CONNECTED: case SS_DATAGRAM: case SS_CONNECTDG:
 133     return events; /* ordinary socket */
 134     break;
 135   }
 136
 137   /*NOTREACHED*/
 138   return 0;
 139 }
 140
 141 /** Set interest events in a pollfd as appropriate.
 142  * @param[in] idx Index of pollfd to operate on.
 143  * @param[in] clear Set of interest events to clear from socket.
 144  * @param[in] set Set of interest events to set on socket.
 145  */
 146 static void
 147 set_or_clear(int idx, unsigned int clear, unsigned int set)
 148 {
 149   if ((clear ^ set) & SOCK_EVENT_READABLE) { /* readable has changed */
 150     if (set & SOCK_EVENT_READABLE) /* it's set */
 151       pollfdList[idx].events |= POLLREADFLAGS;
 152     else /* clear it */
 153       pollfdList[idx].events &= ~POLLREADFLAGS;
 154   }
 155
 156   if ((clear ^ set) & SOCK_EVENT_WRITABLE) { /* writable has changed */
 157     if (set & SOCK_EVENT_WRITABLE) /* it's set */
 158       pollfdList[idx].events |= POLLWRITEFLAGS;
 159     else /* clear it */
 160       pollfdList[idx].events &= ~POLLWRITEFLAGS;
 161   }
 162 }
 163
 164 /** Add a socket to the event engine.
 165  * @param[in] sock Socket to add to engine.
 166  * @return Non-zero on success, or zero on error.
 167  */
 168 static int
 169 engine_add(struct Socket* sock)
 170 {
 171   int i;
 172
 173   assert(0 != sock);
 174
 175   for (i = 0; sockList[i] && i < poll_count; i++) /* Find an empty slot */
 176     ;
 177
 178   Debug((DEBUG_ENGINE, "poll: Looking at slot %d, contents %p", i,
 179          sockList[i]));
 180
 181   if (i >= poll_count) { /* ok, need to allocate another off the list */
 182     if (poll_count >= poll_max) { /* bounds-check... */
 183       log_write(LS_SYSTEM, L_ERROR, 0,
 184                 "Attempt to add socket %d (> %d) to event engine", sock->s_fd,
 185                 poll_max);
 186       return 0;
 187     }
 188
 189     i = poll_count++;
 190     Debug((DEBUG_ENGINE, "poll: Allocating a new slot: %d", i));
 191   }
 192
 193   s_ed_int(sock) = i; /* set engine data */
 194   sockList[i] = sock; /* enter socket into data structures */
 195   pollfdList[i].fd = s_fd(sock);
 196
 197   Debug((DEBUG_ENGINE, "poll: Adding socket %d to engine on %d [%p], state %s",
 198          s_fd(sock), s_ed_int(sock), sock, state_to_name(s_state(sock))));
 199
 200   /* set the appropriate bits */
 201   set_or_clear(i, 0, state_to_events(s_state(sock), s_events(sock)));
 202
 203   return 1; /* success */
 204 }
 205
 206 /** Handle state transition for a socket.
 207  * @param[in] sock Socket changing state.
 208  * @param[in] new_state New state for socket.
 209  */
 210 static void
 211 engine_state(struct Socket* sock, enum SocketState new_state)
 212 {
 213   assert(0 != sock);
 214   assert(sock == sockList[s_ed_int(sock)]);
 215   assert(s_fd(sock) == pollfdList[s_ed_int(sock)].fd);
 216
 217   Debug((DEBUG_ENGINE, "poll: Changing state for socket %p to %s", sock,
 218          state_to_name(new_state)));
 219
 220   /* set the correct events */
 221   set_or_clear(s_ed_int(sock),
 222                state_to_events(s_state(sock), s_events(sock)), /* old state */
 223                state_to_events(new_state, s_events(sock))); /* new state */
 224 }
 225
 226 /** Handle change to preferred socket events.
 227  * @param[in] sock Socket getting new interest list.
 228  * @param[in] new_events New set of interesting events for socket.
 229  */
 230 static void
 231 engine_events(struct Socket* sock, unsigned int new_events)
 232 {
 233   assert(0 != sock);
 234   assert(sock == sockList[s_ed_int(sock)]);
 235   assert(s_fd(sock) == pollfdList[s_ed_int(sock)].fd);
 236
 237   Debug((DEBUG_ENGINE, "poll: Changing event mask for socket %p to [%s]", sock,
 238          sock_flags(new_events)));
 239
 240   /* set the correct events */
 241   set_or_clear(s_ed_int(sock),
 242                state_to_events(s_state(sock), s_events(sock)), /* old events */
 243                state_to_events(s_state(sock), new_events)); /* new events */
 244 }
 245
 246 /** Remove a socket from the event engine.
 247  * @param[in] sock Socket being destroyed.
 248  */
 249 static void
 250 engine_delete(struct Socket* sock)
 251 {
 252   assert(0 != sock);
 253   assert(sock == sockList[s_ed_int(sock)]);
 254   assert(s_fd(sock) == pollfdList[s_ed_int(sock)].fd);
 255
 256   Debug((DEBUG_ENGINE, "poll: Deleting socket %d (%d) [%p], state %s",
 257          s_fd(sock), s_ed_int(sock), sock, state_to_name(s_state(sock))));
 258
 259   /* clear the events */
 260   pollfdList[s_ed_int(sock)].fd = -1;
 261   pollfdList[s_ed_int(sock)].events = 0;
 262
 263   /* zero the socket list entry */
 264   sockList[s_ed_int(sock)] = 0;
 265
 266   /* update poll_count */
 267   while (poll_count > 0 && sockList[poll_count - 1] == 0)
 268     poll_count--;
 269 }
 270
 271 /** Run engine event loop.
 272  * @param[in] gen Lists of generators of various types.
 273  */
 274 static void
 275 engine_loop(struct Generators* gen)
 276 {
 277   int wait;
 278   int nfds;
 279   int i;
 280   int errcode;
 281   socklen_t codesize;
 282   struct Socket *sock;
 283
 284   while (running) {
 285     wait = timer_next(gen) ? (timer_next(gen) - CurrentTime) * 1000 : -1;
 286
 287     Debug((DEBUG_INFO, "poll: delay: %Tu (%Tu) %d", timer_next(gen),
 288            CurrentTime, wait));
 289
 290     /* check for active files */
 291     nfds = poll(pollfdList, poll_count, wait);
 292
 293     CurrentTime = time(0); /* set current time... */
 294
 295     if (nfds < 0) {
 296       if (errno != EINTR) { /* ignore poll interrupts */
 297         /* Log the poll error */
 298         log_write(LS_SOCKET, L_ERROR, 0, "poll() error: %m");
 299         if (!errors++)
 300           timer_add(timer_init(&clear_error), error_clear, 0, TT_PERIODIC,
 301                     ERROR_EXPIRE_TIME);
 302         else if (errors > POLL_ERROR_THRESHOLD) /* too many errors... */
 303           server_restart("too many poll errors");
 304       }
 305       /* old code did a sleep(1) here; with usage these days,
 306        * that may be too expensive
 307        */
 308       continue;
 309     }
 310
 311     for (i = 0; nfds && i < poll_count; i++) {
 312       if (!(sock = sockList[i])) /* skip empty socket elements */
 313         continue;
 314
 315       assert(s_fd(sock) == pollfdList[i].fd);
 316
 317       gen_ref_inc(sock); /* can't have it going away on us */
 318
 319       Debug((DEBUG_ENGINE, "poll: Checking socket %p (fd %d, index %d, "
 320              "state %s, events %s", sock, s_fd(sock), i,
 321              state_to_name(s_state(sock)), sock_flags(s_events(sock))));
 322
 323       if (s_state(sock) != SS_NOTSOCK) {
 324         errcode = 0; /* check for errors on socket */
 325         codesize = sizeof(errcode);
 326         if (getsockopt(s_fd(sock), SOL_SOCKET, SO_ERROR, &errcode,
 327                        &codesize) < 0)
 328           errcode = errno; /* work around Solaris implementation */
 329
 330         if (errcode) { /* an error occurred; generate an event */
 331           Debug((DEBUG_ENGINE, "poll: Error %d on fd %d (index %d), socket %p",
 332                  errcode, s_fd(sock), i, sock));
 333           event_generate(ET_ERROR, sock, errcode);
 334           gen_ref_dec(sock); /* careful not to leak ref counts */
 335           nfds--;
 336           continue;
 337         }
 338       }
 339
 340 #ifdef POLLHUP
 341       if (pollfdList[i].revents & POLLHUP) { /* hang-up on socket */
 342         Debug((DEBUG_ENGINE, "poll: EOF from client (POLLHUP)"));
 343         event_generate(ET_EOF, sock, 0);
 344         nfds--;
 345         continue;
 346       }
 347 #endif /* POLLHUP */
 348
 349       switch (s_state(sock)) {
 350       case SS_CONNECTING:
 351         if (pollfdList[i].revents & POLLWRITEFLAGS) { /* connect completed */
 352           Debug((DEBUG_ENGINE, "poll: Connection completed"));
 353           event_generate(ET_CONNECT, sock, 0);
 354           nfds--;
 355         }
 356         break;
 357
 358       case SS_LISTENING:
 359         if (pollfdList[i].revents & POLLREADFLAGS) { /* ready for accept */
 360           Debug((DEBUG_ENGINE, "poll: Ready for accept"));
 361           event_generate(ET_ACCEPT, sock, 0);
 362           nfds--;
 363         }
 364         break;
 365
 366       case SS_NOTSOCK:
 367         if (pollfdList[i].revents & POLLREADFLAGS) { /* data on socket */
 368           /* can't peek; it's not a socket */
 369           Debug((DEBUG_ENGINE, "poll: non-socket readable"));
 370           event_generate(ET_READ, sock, 0);
 371           nfds--;
 372         }
 373         break;
 374
 375       case SS_CONNECTED:
 376         if (pollfdList[i].revents & POLLREADFLAGS) { /* data on socket */
 377           char c;
 378
 379           switch (recv(s_fd(sock), &c, 1, MSG_PEEK)) { /* check EOF */
 380           case -1: /* error occurred?!? */
 381             if (errno == EAGAIN) {
 382               Debug((DEBUG_ENGINE, "poll: Resource temporarily unavailable?"));
 383               continue;
 384             }
 385             Debug((DEBUG_ENGINE, "poll: Uncaught error!"));
 386             event_generate(ET_ERROR, sock, errno);
 387             break;
 388
 389           case 0: /* EOF from client */
 390             Debug((DEBUG_ENGINE, "poll: EOF from client"));
 391             event_generate(ET_EOF, sock, 0);
 392             break;
 393
 394           default: /* some data can be read */
 395             Debug((DEBUG_ENGINE, "poll: Data to be read"));
 396             event_generate(ET_READ, sock, 0);
 397             break;
 398           }
 399         }
 400         if (pollfdList[i].revents & POLLWRITEFLAGS) { /* socket writable */
 401           Debug((DEBUG_ENGINE, "poll: Data can be written"));
 402           event_generate(ET_WRITE, sock, 0);
 403         }
 404         if (pollfdList[i].revents & (POLLREADFLAGS | POLLWRITEFLAGS))
 405           nfds--;
 406         break;
 407
 408       case SS_DATAGRAM: case SS_CONNECTDG:
 409         if (pollfdList[i].revents & POLLREADFLAGS) { /* socket readable */
 410           Debug((DEBUG_ENGINE, "poll: Datagram to be read"));
 411           event_generate(ET_READ, sock, 0);
 412         }
 413         if (pollfdList[i].revents & POLLWRITEFLAGS) { /* socket writable */
 414           Debug((DEBUG_ENGINE, "poll: Datagram can be written"));
 415           event_generate(ET_WRITE, sock, 0);
 416         }
 417         if (pollfdList[i].revents & (POLLREADFLAGS | POLLWRITEFLAGS))
 418           nfds--;
 419         break;
 420       }
 421
 422       gen_ref_dec(sock); /* we're done with it */
 423     }
 424
 425     timer_run(); /* execute any pending timers */
 426   }
 427 }
 428
 429 /** Descriptor for poll() event engine. */
 430 struct Engine engine_poll = {
 431   "poll()",             /* Engine name */
 432   engine_init,          /* Engine initialization function */
 433   0,                    /* Engine signal registration function */
 434   engine_add,           /* Engine socket registration function */
 435   engine_state,         /* Engine socket state change function */
 436   engine_events,        /* Engine socket events mask function */
 437   engine_delete,        /* Engine socket deletion function */
 438   engine_loop           /* Core engine event loop */
 439 };