3634ad448237df378740c0d3f838aff3f74b79de
[exim.git] / src / src / daemon.c
1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
4
5 /* Copyright (c) University of Cambridge 1995 - 2016 */
6 /* See the file NOTICE for conditions of use and distribution. */
7
8 /* Functions concerned with running Exim as a daemon */
9
10
11 #include "exim.h"
12
13
14 /* Structure for holding data for each SMTP connection */
15
16 typedef struct smtp_slot {
17 pid_t pid; /* pid of the spawned reception process */
18 uschar *host_address; /* address of the client host */
19 } smtp_slot;
20
21 /* An empty slot for initializing (Standard C does not allow constructor
22 expressions in assigments except as initializers in declarations). */
23
24 static smtp_slot empty_smtp_slot = { 0, NULL };
25
26
27
28 /*************************************************
29 * Local static variables *
30 *************************************************/
31
32 static SIGNAL_BOOL sigchld_seen;
33 static SIGNAL_BOOL sighup_seen;
34
35 static int accept_retry_count = 0;
36 static int accept_retry_errno;
37 static BOOL accept_retry_select_failed;
38
39 static int queue_run_count = 0;
40 static pid_t *queue_pid_slots = NULL;
41 static smtp_slot *smtp_slots = NULL;
42
43 static BOOL write_pid = TRUE;
44
45
46
47 /*************************************************
48 * SIGHUP Handler *
49 *************************************************/
50
51 /* All this handler does is to set a flag and re-enable the signal.
52
53 Argument: the signal number
54 Returns: nothing
55 */
56
57 static void
58 sighup_handler(int sig)
59 {
60 sig = sig; /* Keep picky compilers happy */
61 sighup_seen = TRUE;
62 signal(SIGHUP, sighup_handler);
63 }
64
65
66
67 /*************************************************
68 * SIGCHLD handler for main daemon process *
69 *************************************************/
70
71 /* Don't re-enable the handler here, since we aren't doing the
72 waiting here. If the signal is re-enabled, there will just be an
73 infinite sequence of calls to this handler. The SIGCHLD signal is
74 used just as a means of waking up the daemon so that it notices
75 terminated subprocesses as soon as possible.
76
77 Argument: the signal number
78 Returns: nothing
79 */
80
81 static void
82 main_sigchld_handler(int sig)
83 {
84 sig = sig; /* Keep picky compilers happy */
85 os_non_restarting_signal(SIGCHLD, SIG_DFL);
86 sigchld_seen = TRUE;
87 }
88
89
90
91
92 /*************************************************
93 * Unexpected errors in SMTP calls *
94 *************************************************/
95
96 /* This function just saves a bit of repetitious coding.
97
98 Arguments:
99 log_msg Text of message to be logged
100 smtp_msg Text of SMTP error message
101 was_errno The failing errno
102
103 Returns: nothing
104 */
105
106 static void
107 never_error(uschar *log_msg, uschar *smtp_msg, int was_errno)
108 {
109 uschar *emsg = (was_errno <= 0)? US"" :
110 string_sprintf(": %s", strerror(was_errno));
111 log_write(0, LOG_MAIN|LOG_PANIC, "%s%s", log_msg, emsg);
112 if (smtp_out != NULL) smtp_printf("421 %s\r\n", smtp_msg);
113 }
114
115
116
117
118 /*************************************************
119 * Handle a connected SMTP call *
120 *************************************************/
121
122 /* This function is called when an SMTP connection has been accepted.
123 If there are too many, give an error message and close down. Otherwise
124 spin off a sub-process to handle the call. The list of listening sockets
125 is required so that they can be closed in the sub-process. Take care not to
126 leak store in this process - reset the stacking pool at the end.
127
128 Arguments:
129 listen_sockets sockets which are listening for incoming calls
130 listen_socket_count count of listening sockets
131 accept_socket socket of the current accepted call
132 accepted socket information about the current call
133
134 Returns: nothing
135 */
136
137 static void
138 handle_smtp_call(int *listen_sockets, int listen_socket_count,
139 int accept_socket, struct sockaddr *accepted)
140 {
141 pid_t pid;
142 union sockaddr_46 interface_sockaddr;
143 EXIM_SOCKLEN_T ifsize = sizeof(interface_sockaddr);
144 int dup_accept_socket = -1;
145 int max_for_this_host = 0;
146 int wfsize = 0;
147 int wfptr = 0;
148 int save_log_selector = *log_selector;
149 uschar *whofrom = NULL;
150
151 void *reset_point = store_get(0);
152
153 /* Make the address available in ASCII representation, and also fish out
154 the remote port. */
155
156 sender_host_address = host_ntoa(-1, accepted, NULL, &sender_host_port);
157 DEBUG(D_any) debug_printf("Connection request from %s port %d\n",
158 sender_host_address, sender_host_port);
159
160 /* Set up the output stream, check the socket has duplicated, and set up the
161 input stream. These operations fail only the exceptional circumstances. Note
162 that never_error() won't use smtp_out if it is NULL. */
163
164 smtp_out = fdopen(accept_socket, "wb");
165 if (smtp_out == NULL)
166 {
167 never_error(US"daemon: fdopen() for smtp_out failed", US"", errno);
168 goto ERROR_RETURN;
169 }
170
171 dup_accept_socket = dup(accept_socket);
172 if (dup_accept_socket < 0)
173 {
174 never_error(US"daemon: couldn't dup socket descriptor",
175 US"Connection setup failed", errno);
176 goto ERROR_RETURN;
177 }
178
179 smtp_in = fdopen(dup_accept_socket, "rb");
180 if (smtp_in == NULL)
181 {
182 never_error(US"daemon: fdopen() for smtp_in failed",
183 US"Connection setup failed", errno);
184 goto ERROR_RETURN;
185 }
186
187 /* Get the data for the local interface address. Panic for most errors, but
188 "connection reset by peer" just means the connection went away. */
189
190 if (getsockname(accept_socket, (struct sockaddr *)(&interface_sockaddr),
191 &ifsize) < 0)
192 {
193 log_write(0, LOG_MAIN | ((errno == ECONNRESET)? 0 : LOG_PANIC),
194 "getsockname() failed: %s", strerror(errno));
195 smtp_printf("421 Local problem: getsockname() failed; please try again later\r\n");
196 goto ERROR_RETURN;
197 }
198
199 interface_address = host_ntoa(-1, &interface_sockaddr, NULL, &interface_port);
200 DEBUG(D_interface) debug_printf("interface address=%s port=%d\n",
201 interface_address, interface_port);
202
203 /* Build a string identifying the remote host and, if requested, the port and
204 the local interface data. This is for logging; at the end of this function the
205 memory is reclaimed. */
206
207 whofrom = string_append(whofrom, &wfsize, &wfptr, 3, "[", sender_host_address, "]");
208
209 if (LOGGING(incoming_port))
210 whofrom = string_append(whofrom, &wfsize, &wfptr, 2, ":", string_sprintf("%d",
211 sender_host_port));
212
213 if (LOGGING(incoming_interface))
214 whofrom = string_append(whofrom, &wfsize, &wfptr, 4, " I=[",
215 interface_address, "]:", string_sprintf("%d", interface_port));
216
217 whofrom[wfptr] = 0; /* Terminate the newly-built string */
218
219 /* Check maximum number of connections. We do not check for reserved
220 connections or unacceptable hosts here. That is done in the subprocess because
221 it might take some time. */
222
223 if (smtp_accept_max > 0 && smtp_accept_count >= smtp_accept_max)
224 {
225 DEBUG(D_any) debug_printf("rejecting SMTP connection: count=%d max=%d\n",
226 smtp_accept_count, smtp_accept_max);
227 smtp_printf("421 Too many concurrent SMTP connections; "
228 "please try again later.\r\n");
229 log_write(L_connection_reject,
230 LOG_MAIN, "Connection from %s refused: too many connections",
231 whofrom);
232 goto ERROR_RETURN;
233 }
234
235 /* If a load limit above which only reserved hosts are acceptable is defined,
236 get the load average here, and if there are in fact no reserved hosts, do
237 the test right away (saves a fork). If there are hosts, do the check in the
238 subprocess because it might take time. */
239
240 if (smtp_load_reserve >= 0)
241 {
242 load_average = OS_GETLOADAVG();
243 if (smtp_reserve_hosts == NULL && load_average > smtp_load_reserve)
244 {
245 DEBUG(D_any) debug_printf("rejecting SMTP connection: load average = %.2f\n",
246 (double)load_average/1000.0);
247 smtp_printf("421 Too much load; please try again later.\r\n");
248 log_write(L_connection_reject,
249 LOG_MAIN, "Connection from %s refused: load average = %.2f",
250 whofrom, (double)load_average/1000.0);
251 goto ERROR_RETURN;
252 }
253 }
254
255 /* Check that one specific host (strictly, IP address) is not hogging
256 resources. This is done here to prevent a denial of service attack by someone
257 forcing you to fork lots of times before denying service. The value of
258 smtp_accept_max_per_host is a string which is expanded. This makes it possible
259 to provide host-specific limits according to $sender_host address, but because
260 this is in the daemon mainline, only fast expansions (such as inline address
261 checks) should be used. The documentation is full of warnings. */
262
263 if (smtp_accept_max_per_host != NULL)
264 {
265 uschar *expanded = expand_string(smtp_accept_max_per_host);
266 if (expanded == NULL)
267 {
268 if (!expand_string_forcedfail)
269 log_write(0, LOG_MAIN|LOG_PANIC, "expansion of smtp_accept_max_per_host "
270 "failed for %s: %s", whofrom, expand_string_message);
271 }
272 /* For speed, interpret a decimal number inline here */
273 else
274 {
275 uschar *s = expanded;
276 while (isdigit(*s))
277 max_for_this_host = max_for_this_host * 10 + *s++ - '0';
278 if (*s != 0)
279 log_write(0, LOG_MAIN|LOG_PANIC, "expansion of smtp_accept_max_per_host "
280 "for %s contains non-digit: %s", whofrom, expanded);
281 }
282 }
283
284 /* If we have fewer connections than max_for_this_host, we can skip the tedious
285 per host_address checks. Note that at this stage smtp_accept_count contains the
286 count of *other* connections, not including this one. */
287
288 if ((max_for_this_host > 0) &&
289 (smtp_accept_count >= max_for_this_host))
290 {
291 int i;
292 int host_accept_count = 0;
293 int other_host_count = 0; /* keep a count of non matches to optimise */
294
295 for (i = 0; i < smtp_accept_max; ++i)
296 {
297 if (smtp_slots[i].host_address != NULL)
298 {
299 if (Ustrcmp(sender_host_address, smtp_slots[i].host_address) == 0)
300 host_accept_count++;
301 else
302 other_host_count++;
303
304 /* Testing all these strings is expensive - see if we can drop out
305 early, either by hitting the target, or finding there are not enough
306 connections left to make the target. */
307
308 if ((host_accept_count >= max_for_this_host) ||
309 ((smtp_accept_count - other_host_count) < max_for_this_host))
310 break;
311 }
312 }
313
314 if (host_accept_count >= max_for_this_host)
315 {
316 DEBUG(D_any) debug_printf("rejecting SMTP connection: too many from this "
317 "IP address: count=%d max=%d\n",
318 host_accept_count, max_for_this_host);
319 smtp_printf("421 Too many concurrent SMTP connections "
320 "from this IP address; please try again later.\r\n");
321 log_write(L_connection_reject,
322 LOG_MAIN, "Connection from %s refused: too many connections "
323 "from that IP address", whofrom);
324 goto ERROR_RETURN;
325 }
326 }
327
328 /* OK, the connection count checks have been passed. Before we can fork the
329 accepting process, we must first log the connection if requested. This logging
330 used to happen in the subprocess, but doing that means that the value of
331 smtp_accept_count can be out of step by the time it is logged. So we have to do
332 the logging here and accept the performance cost. Note that smtp_accept_count
333 hasn't yet been incremented to take account of this connection.
334
335 In order to minimize the cost (because this is going to happen for every
336 connection), do a preliminary selector test here. This saves ploughing through
337 the generalized logging code each time when the selector is false. If the
338 selector is set, check whether the host is on the list for logging. If not,
339 arrange to unset the selector in the subprocess. */
340
341 if (LOGGING(smtp_connection))
342 {
343 uschar *list = hosts_connection_nolog;
344 memset(sender_host_cache, 0, sizeof(sender_host_cache));
345 if (list != NULL && verify_check_host(&list) == OK)
346 save_log_selector &= ~L_smtp_connection;
347 else
348 log_write(L_smtp_connection, LOG_MAIN, "SMTP connection from %s "
349 "(TCP/IP connection count = %d)", whofrom, smtp_accept_count + 1);
350 }
351
352 /* Now we can fork the accepting process; do a lookup tidy, just in case any
353 expansion above did a lookup. */
354
355 search_tidyup();
356 pid = fork();
357
358 /* Handle the child process */
359
360 if (pid == 0)
361 {
362 int i;
363 int queue_only_reason = 0;
364 int old_pool = store_pool;
365 int save_debug_selector = debug_selector;
366 BOOL local_queue_only;
367 BOOL session_local_queue_only;
368 #ifdef SA_NOCLDWAIT
369 struct sigaction act;
370 #endif
371
372 smtp_accept_count++; /* So that it includes this process */
373
374 /* May have been modified for the subprocess */
375
376 *log_selector = save_log_selector;
377
378 /* Get the local interface address into permanent store */
379
380 store_pool = POOL_PERM;
381 interface_address = string_copy(interface_address);
382 store_pool = old_pool;
383
384 /* Check for a tls-on-connect port */
385
386 if (host_is_tls_on_connect_port(interface_port)) tls_in.on_connect = TRUE;
387
388 /* Expand smtp_active_hostname if required. We do not do this any earlier,
389 because it may depend on the local interface address (indeed, that is most
390 likely what it depends on.) */
391
392 smtp_active_hostname = primary_hostname;
393 if (raw_active_hostname != NULL)
394 {
395 uschar *nah = expand_string(raw_active_hostname);
396 if (nah == NULL)
397 {
398 if (!expand_string_forcedfail)
399 {
400 log_write(0, LOG_MAIN|LOG_PANIC, "failed to expand \"%s\" "
401 "(smtp_active_hostname): %s", raw_active_hostname,
402 expand_string_message);
403 smtp_printf("421 Local configuration error; "
404 "please try again later.\r\n");
405 mac_smtp_fflush();
406 search_tidyup();
407 _exit(EXIT_FAILURE);
408 }
409 }
410 else if (nah[0] != 0) smtp_active_hostname = nah;
411 }
412
413 /* Initialize the queueing flags */
414
415 queue_check_only();
416 session_local_queue_only = queue_only;
417
418 /* Close the listening sockets, and set the SIGCHLD handler to SIG_IGN.
419 We also attempt to set things up so that children are automatically reaped,
420 but just in case this isn't available, there's a paranoid waitpid() in the
421 loop too (except for systems where we are sure it isn't needed). See the more
422 extensive comment before the reception loop in exim.c for a fuller
423 explanation of this logic. */
424
425 for (i = 0; i < listen_socket_count; i++) (void)close(listen_sockets[i]);
426
427 /* Set FD_CLOEXEC on the SMTP socket. We don't want any rogue child processes
428 to be able to communicate with them, under any circumstances. */
429 (void)fcntl(accept_socket, F_SETFD,
430 fcntl(accept_socket, F_GETFD) | FD_CLOEXEC);
431 (void)fcntl(dup_accept_socket, F_SETFD,
432 fcntl(dup_accept_socket, F_GETFD) | FD_CLOEXEC);
433
434 #ifdef SA_NOCLDWAIT
435 act.sa_handler = SIG_IGN;
436 sigemptyset(&(act.sa_mask));
437 act.sa_flags = SA_NOCLDWAIT;
438 sigaction(SIGCHLD, &act, NULL);
439 #else
440 signal(SIGCHLD, SIG_IGN);
441 #endif
442
443 /* Attempt to get an id from the sending machine via the RFC 1413
444 protocol. We do this in the sub-process in order not to hold up the
445 main process if there is any delay. Then set up the fullhost information
446 in case there is no HELO/EHLO.
447
448 If debugging is enabled only for the daemon, we must turn if off while
449 finding the id, but turn it on again afterwards so that information about the
450 incoming connection is output. */
451
452 if (debug_daemon) debug_selector = 0;
453 verify_get_ident(IDENT_PORT);
454 host_build_sender_fullhost();
455 debug_selector = save_debug_selector;
456
457 DEBUG(D_any)
458 debug_printf("Process %d is handling incoming connection from %s\n",
459 (int)getpid(), sender_fullhost);
460
461 /* Now disable debugging permanently if it's required only for the daemon
462 process. */
463
464 if (debug_daemon) debug_selector = 0;
465
466 /* If there are too many child processes for immediate delivery,
467 set the session_local_queue_only flag, which is initialized from the
468 configured value and may therefore already be TRUE. Leave logging
469 till later so it will have a message id attached. Note that there is no
470 possibility of re-calculating this per-message, because the value of
471 smtp_accept_count does not change in this subprocess. */
472
473 if (smtp_accept_queue > 0 && smtp_accept_count > smtp_accept_queue)
474 {
475 session_local_queue_only = TRUE;
476 queue_only_reason = 1;
477 }
478
479 /* Handle the start of the SMTP session, then loop, accepting incoming
480 messages from the SMTP connection. The end will come at the QUIT command,
481 when smtp_setup_msg() returns 0. A break in the connection causes the
482 process to die (see accept.c).
483
484 NOTE: We do *not* call smtp_log_no_mail() if smtp_start_session() fails,
485 because a log line has already been written for all its failure exists
486 (usually "connection refused: <reason>") and writing another one is
487 unnecessary clutter. */
488
489 if (!smtp_start_session())
490 {
491 mac_smtp_fflush();
492 search_tidyup();
493 _exit(EXIT_SUCCESS);
494 }
495
496 for (;;)
497 {
498 int rc;
499 message_id[0] = 0; /* Clear out any previous message_id */
500 reset_point = store_get(0); /* Save current store high water point */
501
502 DEBUG(D_any)
503 debug_printf("Process %d is ready for new message\n", (int)getpid());
504
505 /* Smtp_setup_msg() returns 0 on QUIT or if the call is from an
506 unacceptable host or if an ACL "drop" command was triggered, -1 on
507 connection lost, and +1 on validly reaching DATA. Receive_msg() almost
508 always returns TRUE when smtp_input is true; just retry if no message was
509 accepted (can happen for invalid message parameters). However, it can yield
510 FALSE if the connection was forcibly dropped by the DATA ACL. */
511
512 if ((rc = smtp_setup_msg()) > 0)
513 {
514 BOOL ok = receive_msg(FALSE);
515 search_tidyup(); /* Close cached databases */
516 if (!ok) /* Connection was dropped */
517 {
518 mac_smtp_fflush();
519 smtp_log_no_mail(); /* Log no mail if configured */
520 _exit(EXIT_SUCCESS);
521 }
522 if (message_id[0] == 0) continue; /* No message was accepted */
523 }
524 else
525 {
526 mac_smtp_fflush();
527 search_tidyup();
528 smtp_log_no_mail(); /* Log no mail if configured */
529 _exit((rc == 0)? EXIT_SUCCESS : EXIT_FAILURE);
530 }
531
532 /* Show the recipients when debugging */
533
534 DEBUG(D_receive)
535 {
536 int i;
537 if (sender_address != NULL)
538 debug_printf("Sender: %s\n", sender_address);
539 if (recipients_list != NULL)
540 {
541 debug_printf("Recipients:\n");
542 for (i = 0; i < recipients_count; i++)
543 debug_printf(" %s\n", recipients_list[i].address);
544 }
545 }
546
547 /* A message has been accepted. Clean up any previous delivery processes
548 that have completed and are defunct, on systems where they don't go away
549 by themselves (see comments when setting SIG_IGN above). On such systems
550 (if any) these delivery processes hang around after termination until
551 the next message is received. */
552
553 #ifndef SIG_IGN_WORKS
554 while (waitpid(-1, NULL, WNOHANG) > 0);
555 #endif
556
557 /* Reclaim up the store used in accepting this message */
558
559 store_reset(reset_point);
560
561 /* If queue_only is set or if there are too many incoming connections in
562 existence, session_local_queue_only will be TRUE. If it is not, check
563 whether we have received too many messages in this session for immediate
564 delivery. */
565
566 if (!session_local_queue_only &&
567 smtp_accept_queue_per_connection > 0 &&
568 receive_messagecount > smtp_accept_queue_per_connection)
569 {
570 session_local_queue_only = TRUE;
571 queue_only_reason = 2;
572 }
573
574 /* Initialize local_queue_only from session_local_queue_only. If it is not
575 true, and queue_only_load is set, check that the load average is below it.
576 If local_queue_only is set by this means, we also set if for the session if
577 queue_only_load_latch is true (the default). This means that, once set,
578 local_queue_only remains set for any subsequent messages on the same SMTP
579 connection. This is a deliberate choice; even though the load average may
580 fall, it doesn't seem right to deliver later messages on the same call when
581 not delivering earlier ones. However, the are special circumstances such as
582 very long-lived connections from scanning appliances where this is not the
583 best strategy. In such cases, queue_only_load_latch should be set false. */
584
585 local_queue_only = session_local_queue_only;
586 if (!local_queue_only && queue_only_load >= 0)
587 {
588 local_queue_only = (load_average = OS_GETLOADAVG()) > queue_only_load;
589 if (local_queue_only)
590 {
591 queue_only_reason = 3;
592 if (queue_only_load_latch) session_local_queue_only = TRUE;
593 }
594 }
595
596 /* Log the queueing here, when it will get a message id attached, but
597 not if queue_only is set (case 0). */
598
599 if (local_queue_only) switch(queue_only_reason)
600 {
601 case 1:
602 log_write(L_delay_delivery,
603 LOG_MAIN, "no immediate delivery: too many connections "
604 "(%d, max %d)", smtp_accept_count, smtp_accept_queue);
605 break;
606
607 case 2:
608 log_write(L_delay_delivery,
609 LOG_MAIN, "no immediate delivery: more than %d messages "
610 "received in one connection", smtp_accept_queue_per_connection);
611 break;
612
613 case 3:
614 log_write(L_delay_delivery,
615 LOG_MAIN, "no immediate delivery: load average %.2f",
616 (double)load_average/1000.0);
617 break;
618 }
619
620 /* If a delivery attempt is required, spin off a new process to handle it.
621 If we are not root, we have to re-exec exim unless deliveries are being
622 done unprivileged. */
623
624 else if (!queue_only_policy && !deliver_freeze)
625 {
626 pid_t dpid;
627
628 /* Before forking, ensure that the C output buffer is flushed. Otherwise
629 anything that it in it will get duplicated, leading to duplicate copies
630 of the pending output. */
631
632 mac_smtp_fflush();
633
634 if ((dpid = fork()) == 0)
635 {
636 (void)fclose(smtp_in);
637 (void)fclose(smtp_out);
638
639 /* Don't ever molest the parent's SSL connection, but do clean up
640 the data structures if necessary. */
641
642 #ifdef SUPPORT_TLS
643 tls_close(TRUE, FALSE);
644 #endif
645
646 /* Reset SIGHUP and SIGCHLD in the child in both cases. */
647
648 signal(SIGHUP, SIG_DFL);
649 signal(SIGCHLD, SIG_DFL);
650
651 if (geteuid() != root_uid && !deliver_drop_privilege)
652 {
653 signal(SIGALRM, SIG_DFL);
654 (void)child_exec_exim(CEE_EXEC_PANIC, FALSE, NULL, FALSE, 2, US"-Mc",
655 message_id);
656 /* Control does not return here. */
657 }
658
659 /* No need to re-exec; SIGALRM remains set to the default handler */
660
661 (void)deliver_message(message_id, FALSE, FALSE);
662 search_tidyup();
663 _exit(EXIT_SUCCESS);
664 }
665
666 if (dpid > 0)
667 {
668 DEBUG(D_any) debug_printf("forked delivery process %d\n", (int)dpid);
669 }
670 else
671 {
672 log_write(0, LOG_MAIN|LOG_PANIC, "daemon: delivery process fork "
673 "failed: %s", strerror(errno));
674 }
675 }
676 }
677 }
678
679
680 /* Carrying on in the parent daemon process... Can't do much if the fork
681 failed. Otherwise, keep count of the number of accepting processes and
682 remember the pid for ticking off when the child completes. */
683
684 if (pid < 0)
685 {
686 never_error(US"daemon: accept process fork failed", US"Fork failed", errno);
687 }
688 else
689 {
690 int i;
691 for (i = 0; i < smtp_accept_max; ++i)
692 {
693 if (smtp_slots[i].pid <= 0)
694 {
695 smtp_slots[i].pid = pid;
696 if (smtp_accept_max_per_host != NULL)
697 smtp_slots[i].host_address = string_copy_malloc(sender_host_address);
698 smtp_accept_count++;
699 break;
700 }
701 }
702 DEBUG(D_any) debug_printf("%d SMTP accept process%s running\n",
703 smtp_accept_count, (smtp_accept_count == 1)? "" : "es");
704 }
705
706 /* Get here via goto in error cases */
707
708 ERROR_RETURN:
709
710 /* Close the streams associated with the socket which will also close the
711 socket fds in this process. We can't do anything if fclose() fails, but
712 logging brings it to someone's attention. However, "connection reset by peer"
713 isn't really a problem, so skip that one. On Solaris, a dropped connection can
714 manifest itself as a broken pipe, so drop that one too. If the streams don't
715 exist, something went wrong while setting things up. Make sure the socket
716 descriptors are closed, in order to drop the connection. */
717
718 if (smtp_out != NULL)
719 {
720 if (fclose(smtp_out) != 0 && errno != ECONNRESET && errno != EPIPE)
721 log_write(0, LOG_MAIN|LOG_PANIC, "daemon: fclose(smtp_out) failed: %s",
722 strerror(errno));
723 smtp_out = NULL;
724 }
725 else (void)close(accept_socket);
726
727 if (smtp_in != NULL)
728 {
729 if (fclose(smtp_in) != 0 && errno != ECONNRESET && errno != EPIPE)
730 log_write(0, LOG_MAIN|LOG_PANIC, "daemon: fclose(smtp_in) failed: %s",
731 strerror(errno));
732 smtp_in = NULL;
733 }
734 else (void)close(dup_accept_socket);
735
736 /* Release any store used in this process, including the store used for holding
737 the incoming host address and an expanded active_hostname. */
738
739 log_close_all();
740 store_reset(reset_point);
741 sender_host_address = NULL;
742 }
743
744
745
746
747 /*************************************************
748 * Check wildcard listen special cases *
749 *************************************************/
750
751 /* This function is used when binding and listening on lists of addresses and
752 ports. It tests for special cases of wildcard listening, when IPv4 and IPv6
753 sockets may interact in different ways in different operating systems. It is
754 passed an error number, the list of listening addresses, and the current
755 address. Two checks are available: for a previous wildcard IPv6 address, or for
756 a following wildcard IPv4 address, in both cases on the same port.
757
758 In practice, pairs of wildcard addresses should be adjacent in the address list
759 because they are sorted that way below.
760
761 Arguments:
762 eno the error number
763 addresses the list of addresses
764 ipa the current IP address
765 back if TRUE, check for previous wildcard IPv6 address
766 if FALSE, check for a following wildcard IPv4 address
767
768 Returns: TRUE or FALSE
769 */
770
771 static BOOL
772 check_special_case(int eno, ip_address_item *addresses, ip_address_item *ipa,
773 BOOL back)
774 {
775 ip_address_item *ipa2;
776
777 /* For the "back" case, if the failure was "address in use" for a wildcard IPv4
778 address, seek a previous IPv6 wildcard address on the same port. As it is
779 previous, it must have been successfully bound and be listening. Flag it as a
780 "6 including 4" listener. */
781
782 if (back)
783 {
784 if (eno != EADDRINUSE || ipa->address[0] != 0) return FALSE;
785 for (ipa2 = addresses; ipa2 != ipa; ipa2 = ipa2->next)
786 {
787 if (ipa2->address[1] == 0 && ipa2->port == ipa->port)
788 {
789 ipa2->v6_include_v4 = TRUE;
790 return TRUE;
791 }
792 }
793 }
794
795 /* For the "forward" case, if the current address is a wildcard IPv6 address,
796 we seek a following wildcard IPv4 address on the same port. */
797
798 else
799 {
800 if (ipa->address[0] != ':' || ipa->address[1] != 0) return FALSE;
801 for (ipa2 = ipa->next; ipa2 != NULL; ipa2 = ipa2->next)
802 if (ipa2->address[0] == 0 && ipa->port == ipa2->port) return TRUE;
803 }
804
805 return FALSE;
806 }
807
808
809
810
811 /*************************************************
812 * Handle terminating subprocesses *
813 *************************************************/
814
815 /* Handle the termination of child processes. Theoretically, this need be done
816 only when sigchld_seen is TRUE, but rumour has it that some systems lose
817 SIGCHLD signals at busy times, so to be on the safe side, this function is
818 called each time round. It shouldn't be too expensive.
819
820 Arguments: none
821 Returns: nothing
822 */
823
824 static void
825 handle_ending_processes(void)
826 {
827 int status;
828 pid_t pid;
829
830 while ((pid = waitpid(-1, &status, WNOHANG)) > 0)
831 {
832 int i;
833 DEBUG(D_any)
834 {
835 debug_printf("child %d ended: status=0x%x\n", (int)pid, status);
836 #ifdef WCOREDUMP
837 if (WIFEXITED(status))
838 debug_printf(" normal exit, %d\n", WEXITSTATUS(status));
839 else if (WIFSIGNALED(status))
840 debug_printf(" signal exit, signal %d%s\n", WTERMSIG(status),
841 WCOREDUMP(status) ? " (core dumped)" : "");
842 #endif
843 }
844
845 /* If it's a listening daemon for which we are keeping track of individual
846 subprocesses, deal with an accepting process that has terminated. */
847
848 if (smtp_slots != NULL)
849 {
850 for (i = 0; i < smtp_accept_max; i++)
851 {
852 if (smtp_slots[i].pid == pid)
853 {
854 if (smtp_slots[i].host_address != NULL)
855 store_free(smtp_slots[i].host_address);
856 smtp_slots[i] = empty_smtp_slot;
857 if (--smtp_accept_count < 0) smtp_accept_count = 0;
858 DEBUG(D_any) debug_printf("%d SMTP accept process%s now running\n",
859 smtp_accept_count, (smtp_accept_count == 1)? "" : "es");
860 break;
861 }
862 }
863 if (i < smtp_accept_max) continue; /* Found an accepting process */
864 }
865
866 /* If it wasn't an accepting process, see if it was a queue-runner
867 process that we are tracking. */
868
869 if (queue_pid_slots)
870 {
871 int max = atoi(expand_string(queue_run_max));
872 for (i = 0; i < max; i++)
873 if (queue_pid_slots[i] == pid)
874 {
875 queue_pid_slots[i] = 0;
876 if (--queue_run_count < 0) queue_run_count = 0;
877 DEBUG(D_any) debug_printf("%d queue-runner process%s now running\n",
878 queue_run_count, (queue_run_count == 1)? "" : "es");
879 break;
880 }
881 }
882 }
883 }
884
885
886
887 /*************************************************
888 * Exim Daemon Mainline *
889 *************************************************/
890
891 /* The daemon can do two jobs, either of which is optional:
892
893 (1) Listens for incoming SMTP calls and spawns off a sub-process to handle
894 each one. This is requested by the -bd option, with -oX specifying the SMTP
895 port on which to listen (for testing).
896
897 (2) Spawns a queue-running process every so often. This is controlled by the
898 -q option with a an interval time. (If no time is given, a single queue run
899 is done from the main function, and control doesn't get here.)
900
901 Root privilege is required in order to attach to port 25. Some systems require
902 it when calling socket() rather than bind(). To cope with all cases, we run as
903 root for both socket() and bind(). Some systems also require root in order to
904 write to the pid file directory. This function must therefore be called as root
905 if it is to work properly in all circumstances. Once the socket is bound and
906 the pid file written, root privilege is given up if there is an exim uid.
907
908 There are no arguments to this function, and it never returns. */
909
910 void
911 daemon_go(void)
912 {
913 struct passwd *pw;
914 int *listen_sockets = NULL;
915 int listen_socket_count = 0;
916 ip_address_item *addresses = NULL;
917 time_t last_connection_time = (time_t)0;
918 int local_queue_run_max = atoi(expand_string(queue_run_max));
919
920 /* If any debugging options are set, turn on the D_pid bit so that all
921 debugging lines get the pid added. */
922
923 DEBUG(D_any|D_v) debug_selector |= D_pid;
924
925 if (inetd_wait_mode)
926 {
927 int on = 1;
928
929 listen_socket_count = 1;
930 listen_sockets = store_get(sizeof(int));
931 (void) close(3);
932 if (dup2(0, 3) == -1)
933 log_write(0, LOG_MAIN|LOG_PANIC_DIE,
934 "failed to dup inetd socket safely away: %s", strerror(errno));
935
936 listen_sockets[0] = 3;
937 (void) close(0);
938 (void) close(1);
939 (void) close(2);
940 exim_nullstd();
941
942 if (debug_file == stderr)
943 {
944 /* need a call to log_write before call to open debug_file, so that
945 log.c:file_path has been initialised. This is unfortunate. */
946 log_write(0, LOG_MAIN, "debugging Exim in inetd wait mode starting");
947
948 fclose(debug_file);
949 debug_file = NULL;
950 exim_nullstd(); /* re-open fd2 after we just closed it again */
951 debug_logging_activate(US"-wait", NULL);
952 }
953
954 DEBUG(D_any) debug_printf("running in inetd wait mode\n");
955
956 /* As per below, when creating sockets ourselves, we handle tcp_nodelay for
957 our own buffering; we assume though that inetd set the socket REUSEADDR. */
958
959 if (tcp_nodelay)
960 if (setsockopt(3, IPPROTO_TCP, TCP_NODELAY, US &on, sizeof(on)))
961 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "failed to set socket NODELAY: %s",
962 strerror(errno));
963 }
964
965
966 if (inetd_wait_mode || daemon_listen)
967 {
968 /* If any option requiring a load average to be available during the
969 reception of a message is set, call os_getloadavg() while we are root
970 for those OS for which this is necessary the first time it is called (in
971 order to perform an "open" on the kernel memory file). */
972
973 #ifdef LOAD_AVG_NEEDS_ROOT
974 if (queue_only_load >= 0 || smtp_load_reserve >= 0 ||
975 (deliver_queue_load_max >= 0 && deliver_drop_privilege))
976 (void)os_getloadavg();
977 #endif
978 }
979
980
981 /* Do the preparation for setting up a listener on one or more interfaces, and
982 possible on various ports. This is controlled by the combination of
983 local_interfaces (which can set IP addresses and ports) and daemon_smtp_port
984 (which is a list of default ports to use for those items in local_interfaces
985 that do not specify a port). The -oX command line option can be used to
986 override one or both of these options.
987
988 If local_interfaces is not set, the default is to listen on all interfaces.
989 When it is set, it can include "all IPvx interfaces" as an item. This is useful
990 when different ports are in use.
991
992 It turns out that listening on all interfaces is messy in an IPv6 world,
993 because several different implementation approaches have been taken. This code
994 is now supposed to work with all of them. The point of difference is whether an
995 IPv6 socket that is listening on all interfaces will receive incoming IPv4
996 calls or not. We also have to cope with the case when IPv6 libraries exist, but
997 there is no IPv6 support in the kernel.
998
999 . On Solaris, an IPv6 socket will accept IPv4 calls, and give them as mapped
1000 addresses. However, if an IPv4 socket is also listening on all interfaces,
1001 calls are directed to the appropriate socket.
1002
1003 . On (some versions of) Linux, an IPv6 socket will accept IPv4 calls, and
1004 give them as mapped addresses, but an attempt also to listen on an IPv4
1005 socket on all interfaces causes an error.
1006
1007 . On OpenBSD, an IPv6 socket will not accept IPv4 calls. You have to set up
1008 two sockets if you want to accept both kinds of call.
1009
1010 . FreeBSD is like OpenBSD, but it has the IPV6_V6ONLY socket option, which
1011 can be turned off, to make it behave like the versions of Linux described
1012 above.
1013
1014 . I heard a report that the USAGI IPv6 stack for Linux has implemented
1015 IPV6_V6ONLY.
1016
1017 So, what we do when IPv6 is supported is as follows:
1018
1019 (1) After it is set up, the list of interfaces is scanned for wildcard
1020 addresses. If an IPv6 and an IPv4 wildcard are both found for the same
1021 port, the list is re-arranged so that they are together, with the IPv6
1022 wildcard first.
1023
1024 (2) If the creation of a wildcard IPv6 socket fails, we just log the error and
1025 carry on if an IPv4 wildcard socket for the same port follows later in the
1026 list. This allows Exim to carry on in the case when the kernel has no IPv6
1027 support.
1028
1029 (3) Having created an IPv6 wildcard socket, we try to set IPV6_V6ONLY if that
1030 option is defined. However, if setting fails, carry on regardless (but log
1031 the incident).
1032
1033 (4) If binding or listening on an IPv6 wildcard socket fails, it is a serious
1034 error.
1035
1036 (5) If binding or listening on an IPv4 wildcard socket fails with the error
1037 EADDRINUSE, and a previous interface was an IPv6 wildcard for the same
1038 port (which must have succeeded or we wouldn't have got this far), we
1039 assume we are in the situation where just a single socket is permitted,
1040 and ignore the error.
1041
1042 Phew!
1043
1044 The preparation code decodes options and sets up the relevant data. We do this
1045 first, so that we can return non-zero if there are any syntax errors, and also
1046 write to stderr. */
1047
1048 if (daemon_listen && !inetd_wait_mode)
1049 {
1050 int *default_smtp_port;
1051 int sep;
1052 int pct = 0;
1053 uschar *s;
1054 const uschar * list;
1055 uschar *local_iface_source = US"local_interfaces";
1056 ip_address_item *ipa;
1057 ip_address_item **pipa;
1058
1059 /* If -oX was used, disable the writing of a pid file unless -oP was
1060 explicitly used to force it. Then scan the string given to -oX. Any items
1061 that contain neither a dot nor a colon are used to override daemon_smtp_port.
1062 Any other items are used to override local_interfaces. */
1063
1064 if (override_local_interfaces != NULL)
1065 {
1066 uschar *new_smtp_port = NULL;
1067 uschar *new_local_interfaces = NULL;
1068 int portsize = 0;
1069 int portptr = 0;
1070 int ifacesize = 0;
1071 int ifaceptr = 0;
1072
1073 if (override_pid_file_path == NULL) write_pid = FALSE;
1074
1075 list = override_local_interfaces;
1076 sep = 0;
1077 while ((s = string_nextinlist(&list, &sep, big_buffer, big_buffer_size)))
1078 {
1079 uschar joinstr[4];
1080 uschar **ptr;
1081 int *sizeptr;
1082 int *ptrptr;
1083
1084 if (Ustrpbrk(s, ".:") == NULL)
1085 {
1086 ptr = &new_smtp_port;
1087 sizeptr = &portsize;
1088 ptrptr = &portptr;
1089 }
1090 else
1091 {
1092 ptr = &new_local_interfaces;
1093 sizeptr = &ifacesize;
1094 ptrptr = &ifaceptr;
1095 }
1096
1097 if (*ptr == NULL)
1098 {
1099 joinstr[0] = sep;
1100 joinstr[1] = ' ';
1101 *ptr = string_catn(*ptr, sizeptr, ptrptr, US"<", 1);
1102 }
1103
1104 *ptr = string_catn(*ptr, sizeptr, ptrptr, joinstr, 2);
1105 *ptr = string_cat (*ptr, sizeptr, ptrptr, s);
1106 }
1107
1108 if (new_smtp_port != NULL)
1109 {
1110 new_smtp_port[portptr] = 0;
1111 daemon_smtp_port = new_smtp_port;
1112 DEBUG(D_any) debug_printf("daemon_smtp_port overridden by -oX:\n %s\n",
1113 daemon_smtp_port);
1114 }
1115
1116 if (new_local_interfaces != NULL)
1117 {
1118 new_local_interfaces[ifaceptr] = 0;
1119 local_interfaces = new_local_interfaces;
1120 local_iface_source = US"-oX data";
1121 DEBUG(D_any) debug_printf("local_interfaces overridden by -oX:\n %s\n",
1122 local_interfaces);
1123 }
1124 }
1125
1126 /* Create a list of default SMTP ports, to be used if local_interfaces
1127 contains entries without explict ports. First count the number of ports, then
1128 build a translated list in a vector. */
1129
1130 list = daemon_smtp_port;
1131 sep = 0;
1132 while ((s = string_nextinlist(&list, &sep, big_buffer, big_buffer_size)))
1133 pct++;
1134 default_smtp_port = store_get((pct+1) * sizeof(int));
1135 list = daemon_smtp_port;
1136 sep = 0;
1137 for (pct = 0;
1138 (s = string_nextinlist(&list, &sep, big_buffer, big_buffer_size));
1139 pct++)
1140 {
1141 if (isdigit(*s))
1142 {
1143 uschar *end;
1144 default_smtp_port[pct] = Ustrtol(s, &end, 0);
1145 if (end != s + Ustrlen(s))
1146 log_write(0, LOG_PANIC_DIE|LOG_CONFIG, "invalid SMTP port: %s", s);
1147 }
1148 else
1149 {
1150 struct servent *smtp_service = getservbyname(CS s, "tcp");
1151 if (!smtp_service)
1152 log_write(0, LOG_PANIC_DIE|LOG_CONFIG, "TCP port \"%s\" not found", s);
1153 default_smtp_port[pct] = ntohs(smtp_service->s_port);
1154 }
1155 }
1156 default_smtp_port[pct] = 0;
1157
1158 /* Check the list of TLS-on-connect ports and do name lookups if needed */
1159
1160 list = tls_in.on_connect_ports;
1161 sep = 0;
1162 while ((s = string_nextinlist(&list, &sep, big_buffer, big_buffer_size)))
1163 if (!isdigit(*s))
1164 {
1165 list = tls_in.on_connect_ports;
1166 tls_in.on_connect_ports = NULL;
1167 sep = 0;
1168 while ((s = string_nextinlist(&list, &sep, big_buffer, big_buffer_size)))
1169 {
1170 if (!isdigit(*s))
1171 {
1172 struct servent *smtp_service = getservbyname(CS s, "tcp");
1173 if (!smtp_service)
1174 log_write(0, LOG_PANIC_DIE|LOG_CONFIG, "TCP port \"%s\" not found", s);
1175 s= string_sprintf("%d", (int)ntohs(smtp_service->s_port));
1176 }
1177 tls_in.on_connect_ports = string_append_listele(tls_in.on_connect_ports,
1178 ':', s);
1179 }
1180 break;
1181 }
1182
1183 /* Create the list of local interfaces, possibly with ports included. This
1184 list may contain references to 0.0.0.0 and ::0 as wildcards. These special
1185 values are converted below. */
1186
1187 addresses = host_build_ifacelist(local_interfaces, local_iface_source);
1188
1189 /* In the list of IP addresses, convert 0.0.0.0 into an empty string, and ::0
1190 into the string ":". We use these to recognize wildcards in IPv4 and IPv6. In
1191 fact, many IP stacks recognize 0.0.0.0 and ::0 and handle them as wildcards
1192 anyway, but we need to know which are the wildcard addresses, and the shorter
1193 strings are neater.
1194
1195 In the same scan, fill in missing port numbers from the default list. When
1196 there is more than one item in the list, extra items are created. */
1197
1198 for (ipa = addresses; ipa != NULL; ipa = ipa->next)
1199 {
1200 int i;
1201
1202 if (Ustrcmp(ipa->address, "0.0.0.0") == 0) ipa->address[0] = 0;
1203 else if (Ustrcmp(ipa->address, "::0") == 0)
1204 {
1205 ipa->address[0] = ':';
1206 ipa->address[1] = 0;
1207 }
1208
1209 if (ipa->port > 0) continue;
1210
1211 if (daemon_smtp_port[0] <= 0)
1212 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "no port specified for interface "
1213 "%s and daemon_smtp_port is unset; cannot start daemon",
1214 (ipa->address[0] == 0)? US"\"all IPv4\"" :
1215 (ipa->address[1] == 0)? US"\"all IPv6\"" : ipa->address);
1216 ipa->port = default_smtp_port[0];
1217 for (i = 1; default_smtp_port[i] > 0; i++)
1218 {
1219 ip_address_item *new = store_get(sizeof(ip_address_item));
1220 memcpy(new->address, ipa->address, Ustrlen(ipa->address) + 1);
1221 new->port = default_smtp_port[i];
1222 new->next = ipa->next;
1223 ipa->next = new;
1224 ipa = new;
1225 }
1226 }
1227
1228 /* Scan the list of addresses for wildcards. If we find an IPv4 and an IPv6
1229 wildcard for the same port, ensure that (a) they are together and (b) the
1230 IPv6 address comes first. This makes handling the messy features easier, and
1231 also simplifies the construction of the "daemon started" log line. */
1232
1233 pipa = &addresses;
1234 for (ipa = addresses; ipa != NULL; pipa = &(ipa->next), ipa = ipa->next)
1235 {
1236 ip_address_item *ipa2;
1237
1238 /* Handle an IPv4 wildcard */
1239
1240 if (ipa->address[0] == 0)
1241 {
1242 for (ipa2 = ipa; ipa2->next != NULL; ipa2 = ipa2->next)
1243 {
1244 ip_address_item *ipa3 = ipa2->next;
1245 if (ipa3->address[0] == ':' &&
1246 ipa3->address[1] == 0 &&
1247 ipa3->port == ipa->port)
1248 {
1249 ipa2->next = ipa3->next;
1250 ipa3->next = ipa;
1251 *pipa = ipa3;
1252 break;
1253 }
1254 }
1255 }
1256
1257 /* Handle an IPv6 wildcard. */
1258
1259 else if (ipa->address[0] == ':' && ipa->address[1] == 0)
1260 {
1261 for (ipa2 = ipa; ipa2->next != NULL; ipa2 = ipa2->next)
1262 {
1263 ip_address_item *ipa3 = ipa2->next;
1264 if (ipa3->address[0] == 0 && ipa3->port == ipa->port)
1265 {
1266 ipa2->next = ipa3->next;
1267 ipa3->next = ipa->next;
1268 ipa->next = ipa3;
1269 ipa = ipa3;
1270 break;
1271 }
1272 }
1273 }
1274 }
1275
1276 /* Get a vector to remember all the sockets in */
1277
1278 for (ipa = addresses; ipa != NULL; ipa = ipa->next)
1279 listen_socket_count++;
1280 listen_sockets = store_get(sizeof(int) * listen_socket_count);
1281
1282 } /* daemon_listen but not inetd_wait_mode */
1283
1284 if (daemon_listen)
1285 {
1286
1287 /* Do a sanity check on the max connects value just to save us from getting
1288 a huge amount of store. */
1289
1290 if (smtp_accept_max > 4095) smtp_accept_max = 4096;
1291
1292 /* There's no point setting smtp_accept_queue unless it is less than the max
1293 connects limit. The configuration reader ensures that the max is set if the
1294 queue-only option is set. */
1295
1296 if (smtp_accept_queue > smtp_accept_max) smtp_accept_queue = 0;
1297
1298 /* Get somewhere to keep the list of SMTP accepting pids if we are keeping
1299 track of them for total number and queue/host limits. */
1300
1301 if (smtp_accept_max > 0)
1302 {
1303 int i;
1304 smtp_slots = store_get(smtp_accept_max * sizeof(smtp_slot));
1305 for (i = 0; i < smtp_accept_max; i++) smtp_slots[i] = empty_smtp_slot;
1306 }
1307 }
1308
1309 /* The variable background_daemon is always false when debugging, but
1310 can also be forced false in order to keep a non-debugging daemon in the
1311 foreground. If background_daemon is true, close all open file descriptors that
1312 we know about, but then re-open stdin, stdout, and stderr to /dev/null. Also
1313 do this for inetd_wait mode.
1314
1315 This is protection against any called functions (in libraries, or in
1316 Perl, or whatever) that think they can write to stderr (or stdout). Before this
1317 was added, it was quite likely that an SMTP connection would use one of these
1318 file descriptors, in which case writing random stuff to it caused chaos.
1319
1320 Then disconnect from the controlling terminal, Most modern Unixes seem to have
1321 setsid() for getting rid of the controlling terminal. For any OS that doesn't,
1322 setsid() can be #defined as a no-op, or as something else. */
1323
1324 if (background_daemon || inetd_wait_mode)
1325 {
1326 log_close_all(); /* Just in case anything was logged earlier */
1327 search_tidyup(); /* Just in case any were used in reading the config. */
1328 (void)close(0); /* Get rid of stdin/stdout/stderr */
1329 (void)close(1);
1330 (void)close(2);
1331 exim_nullstd(); /* Connect stdin/stdout/stderr to /dev/null */
1332 log_stderr = NULL; /* So no attempt to copy paniclog output */
1333 }
1334
1335 if (background_daemon)
1336 {
1337 /* If the parent process of this one has pid == 1, we are re-initializing the
1338 daemon as the result of a SIGHUP. In this case, there is no need to do
1339 anything, because the controlling terminal has long gone. Otherwise, fork, in
1340 case current process is a process group leader (see 'man setsid' for an
1341 explanation) before calling setsid(). */
1342
1343 if (getppid() != 1)
1344 {
1345 pid_t pid = fork();
1346 if (pid < 0) log_write(0, LOG_MAIN|LOG_PANIC_DIE,
1347 "fork() failed when starting daemon: %s", strerror(errno));
1348 if (pid > 0) exit(EXIT_SUCCESS); /* in parent process, just exit */
1349 (void)setsid(); /* release controlling terminal */
1350 }
1351 }
1352
1353 /* We are now in the disconnected, daemon process (unless debugging). Set up
1354 the listening sockets if required. */
1355
1356 if (daemon_listen && !inetd_wait_mode)
1357 {
1358 int sk;
1359 int on = 1;
1360 ip_address_item *ipa;
1361
1362 /* For each IP address, create a socket, bind it to the appropriate port, and
1363 start listening. See comments above about IPv6 sockets that may or may not
1364 accept IPv4 calls when listening on all interfaces. We also have to cope with
1365 the case of a system with IPv6 libraries, but no IPv6 support in the kernel.
1366 listening, provided a wildcard IPv4 socket for the same port follows. */
1367
1368 for (ipa = addresses, sk = 0; sk < listen_socket_count; ipa = ipa->next, sk++)
1369 {
1370 BOOL wildcard;
1371 ip_address_item *ipa2;
1372 int af;
1373
1374 if (Ustrchr(ipa->address, ':') != NULL)
1375 {
1376 af = AF_INET6;
1377 wildcard = ipa->address[1] == 0;
1378 }
1379 else
1380 {
1381 af = AF_INET;
1382 wildcard = ipa->address[0] == 0;
1383 }
1384
1385 if ((listen_sockets[sk] = ip_socket(SOCK_STREAM, af)) < 0)
1386 {
1387 if (check_special_case(0, addresses, ipa, FALSE))
1388 {
1389 log_write(0, LOG_MAIN, "Failed to create IPv6 socket for wildcard "
1390 "listening (%s): will use IPv4", strerror(errno));
1391 goto SKIP_SOCKET;
1392 }
1393 log_write(0, LOG_PANIC_DIE, "IPv%c socket creation failed: %s",
1394 (af == AF_INET6)? '6' : '4', strerror(errno));
1395 }
1396
1397 /* If this is an IPv6 wildcard socket, set IPV6_V6ONLY if that option is
1398 available. Just log failure (can get protocol not available, just like
1399 socket creation can). */
1400
1401 #ifdef IPV6_V6ONLY
1402 if (af == AF_INET6 && wildcard &&
1403 setsockopt(listen_sockets[sk], IPPROTO_IPV6, IPV6_V6ONLY, (char *)(&on),
1404 sizeof(on)) < 0)
1405 log_write(0, LOG_MAIN, "Setting IPV6_V6ONLY on daemon's IPv6 wildcard "
1406 "socket failed (%s): carrying on without it", strerror(errno));
1407 #endif /* IPV6_V6ONLY */
1408
1409 /* Set SO_REUSEADDR so that the daemon can be restarted while a connection
1410 is being handled. Without this, a connection will prevent reuse of the
1411 smtp port for listening. */
1412
1413 if (setsockopt(listen_sockets[sk], SOL_SOCKET, SO_REUSEADDR,
1414 (uschar *)(&on), sizeof(on)) < 0)
1415 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "setting SO_REUSEADDR on socket "
1416 "failed when starting daemon: %s", strerror(errno));
1417
1418 /* Set TCP_NODELAY; Exim does its own buffering. There is a switch to
1419 disable this because it breaks some broken clients. */
1420
1421 if (tcp_nodelay) setsockopt(listen_sockets[sk], IPPROTO_TCP, TCP_NODELAY,
1422 (uschar *)(&on), sizeof(on));
1423
1424 /* Now bind the socket to the required port; if Exim is being restarted
1425 it may not always be possible to bind immediately, even with SO_REUSEADDR
1426 set, so try 10 times, waiting between each try. After 10 failures, we give
1427 up. In an IPv6 environment, if bind () fails with the error EADDRINUSE and
1428 we are doing wildcard IPv4 listening and there was a previous IPv6 wildcard
1429 address for the same port, ignore the error on the grounds that we must be
1430 in a system where the IPv6 socket accepts both kinds of call. This is
1431 necessary for (some release of) USAGI Linux; other IP stacks fail at the
1432 listen() stage instead. */
1433
1434 for(;;)
1435 {
1436 uschar *msg, *addr;
1437 if (ip_bind(listen_sockets[sk], af, ipa->address, ipa->port) >= 0) break;
1438 if (check_special_case(errno, addresses, ipa, TRUE))
1439 {
1440 DEBUG(D_any) debug_printf("wildcard IPv4 bind() failed after IPv6 "
1441 "listen() success; EADDRINUSE ignored\n");
1442 (void)close(listen_sockets[sk]);
1443 goto SKIP_SOCKET;
1444 }
1445 msg = US strerror(errno);
1446 addr = wildcard? ((af == AF_INET6)? US"(any IPv6)" : US"(any IPv4)") :
1447 ipa->address;
1448 if (daemon_startup_retries <= 0)
1449 log_write(0, LOG_MAIN|LOG_PANIC_DIE,
1450 "socket bind() to port %d for address %s failed: %s: "
1451 "daemon abandoned", ipa->port, addr, msg);
1452 log_write(0, LOG_MAIN, "socket bind() to port %d for address %s "
1453 "failed: %s: waiting %s before trying again (%d more %s)",
1454 ipa->port, addr, msg, readconf_printtime(daemon_startup_sleep),
1455 daemon_startup_retries, (daemon_startup_retries > 1)? "tries" : "try");
1456 daemon_startup_retries--;
1457 sleep(daemon_startup_sleep);
1458 }
1459
1460 DEBUG(D_any)
1461 {
1462 if (wildcard)
1463 debug_printf("listening on all interfaces (IPv%c) port %d\n",
1464 (af == AF_INET6)? '6' : '4', ipa->port);
1465 else
1466 debug_printf("listening on %s port %d\n", ipa->address, ipa->port);
1467 }
1468
1469 /* Start listening on the bound socket, establishing the maximum backlog of
1470 connections that is allowed. On success, continue to the next address. */
1471
1472 if (listen(listen_sockets[sk], smtp_connect_backlog) >= 0) continue;
1473
1474 /* Listening has failed. In an IPv6 environment, as for bind(), if listen()
1475 fails with the error EADDRINUSE and we are doing IPv4 wildcard listening
1476 and there was a previous successful IPv6 wildcard listen on the same port,
1477 we want to ignore the error on the grounds that we must be in a system
1478 where the IPv6 socket accepts both kinds of call. */
1479
1480 if (!check_special_case(errno, addresses, ipa, TRUE))
1481 log_write(0, LOG_PANIC_DIE, "listen() failed on interface %s: %s",
1482 wildcard? ((af == AF_INET6)? US"(any IPv6)" : US"(any IPv4)") :
1483 ipa->address,
1484 strerror(errno));
1485
1486 DEBUG(D_any) debug_printf("wildcard IPv4 listen() failed after IPv6 "
1487 "listen() success; EADDRINUSE ignored\n");
1488 (void)close(listen_sockets[sk]);
1489
1490 /* Come here if there has been a problem with the socket which we
1491 are going to ignore. We remove the address from the chain, and back up the
1492 counts. */
1493
1494 SKIP_SOCKET:
1495 sk--; /* Back up the count */
1496 listen_socket_count--; /* Reduce the total */
1497 if (ipa == addresses) addresses = ipa->next; else
1498 {
1499 for (ipa2 = addresses; ipa2->next != ipa; ipa2 = ipa2->next);
1500 ipa2->next = ipa->next;
1501 ipa = ipa2;
1502 }
1503 } /* End of bind/listen loop for each address */
1504 } /* End of setup for listening */
1505
1506
1507 /* If we are not listening, we want to write a pid file only if -oP was
1508 explicitly given. */
1509
1510 else if (override_pid_file_path == NULL) write_pid = FALSE;
1511
1512 /* Write the pid to a known file for assistance in identification, if required.
1513 We do this before giving up root privilege, because on some systems it is
1514 necessary to be root in order to write into the pid file directory. There's
1515 nothing to stop multiple daemons running, as long as no more than one listens
1516 on a given TCP/IP port on the same interface(s). However, in these
1517 circumstances it gets far too complicated to mess with pid file names
1518 automatically. Consequently, Exim 4 writes a pid file only
1519
1520 (a) When running in the test harness, or
1521 (b) When -bd is used and -oX is not used, or
1522 (c) When -oP is used to supply a path.
1523
1524 The variable daemon_write_pid is used to control this. */
1525
1526 if (running_in_test_harness || write_pid)
1527 {
1528 FILE *f;
1529
1530 if (override_pid_file_path != NULL)
1531 pid_file_path = override_pid_file_path;
1532
1533 if (pid_file_path[0] == 0)
1534 pid_file_path = string_sprintf("%s/exim-daemon.pid", spool_directory);
1535
1536 f = modefopen(pid_file_path, "wb", 0644);
1537 if (f != NULL)
1538 {
1539 (void)fprintf(f, "%d\n", (int)getpid());
1540 (void)fclose(f);
1541 DEBUG(D_any) debug_printf("pid written to %s\n", pid_file_path);
1542 }
1543 else
1544 {
1545 DEBUG(D_any)
1546 debug_printf("%s\n", string_open_failed(errno, "pid file %s",
1547 pid_file_path));
1548 }
1549 }
1550
1551 /* Set up the handler for SIGHUP, which causes a restart of the daemon. */
1552
1553 sighup_seen = FALSE;
1554 signal(SIGHUP, sighup_handler);
1555
1556 /* Give up root privilege at this point (assuming that exim_uid and exim_gid
1557 are not root). The third argument controls the running of initgroups().
1558 Normally we do this, in order to set up the groups for the Exim user. However,
1559 if we are not root at this time - some odd installations run that way - we
1560 cannot do this. */
1561
1562 exim_setugid(exim_uid, exim_gid, geteuid()==root_uid, US"running as a daemon");
1563
1564 /* Update the originator_xxx fields so that received messages as listed as
1565 coming from Exim, not whoever started the daemon. */
1566
1567 originator_uid = exim_uid;
1568 originator_gid = exim_gid;
1569 originator_login = ((pw = getpwuid(exim_uid)) != NULL)?
1570 string_copy_malloc(US pw->pw_name) : US"exim";
1571
1572 /* Get somewhere to keep the list of queue-runner pids if we are keeping track
1573 of them (and also if we are doing queue runs). */
1574
1575 if (queue_interval > 0 && local_queue_run_max > 0)
1576 {
1577 int i;
1578 queue_pid_slots = store_get(local_queue_run_max * sizeof(pid_t));
1579 for (i = 0; i < local_queue_run_max; i++) queue_pid_slots[i] = 0;
1580 }
1581
1582 /* Set up the handler for termination of child processes. */
1583
1584 sigchld_seen = FALSE;
1585 os_non_restarting_signal(SIGCHLD, main_sigchld_handler);
1586
1587 /* If we are to run the queue periodically, pretend the alarm has just gone
1588 off. This will cause the first queue-runner to get kicked off straight away. */
1589
1590 sigalrm_seen = (queue_interval > 0);
1591
1592 /* Log the start up of a daemon - at least one of listening or queue running
1593 must be set up. */
1594
1595 if (inetd_wait_mode)
1596 {
1597 uschar *p = big_buffer;
1598
1599 if (inetd_wait_timeout >= 0)
1600 sprintf(CS p, "terminating after %d seconds", inetd_wait_timeout);
1601 else
1602 sprintf(CS p, "with no wait timeout");
1603
1604 log_write(0, LOG_MAIN,
1605 "exim %s daemon started: pid=%d, launched with listening socket, %s",
1606 version_string, getpid(), big_buffer);
1607 set_process_info("daemon(%s): pre-listening socket", version_string);
1608
1609 /* set up the timeout logic */
1610 sigalrm_seen = 1;
1611 }
1612
1613 else if (daemon_listen)
1614 {
1615 int i, j;
1616 int smtp_ports = 0;
1617 int smtps_ports = 0;
1618 ip_address_item *ipa;
1619 uschar *p = big_buffer;
1620 uschar *qinfo = (queue_interval > 0)?
1621 string_sprintf("-q%s", readconf_printtime(queue_interval))
1622 :
1623 US"no queue runs";
1624
1625 /* Build a list of listening addresses in big_buffer, but limit it to 10
1626 items. The style is for backwards compatibility.
1627
1628 It is now possible to have some ports listening for SMTPS (the old,
1629 deprecated protocol that starts TLS without using STARTTLS), and others
1630 listening for standard SMTP. Keep their listings separate. */
1631
1632 for (j = 0; j < 2; j++)
1633 {
1634 for (i = 0, ipa = addresses; i < 10 && ipa != NULL; i++, ipa = ipa->next)
1635 {
1636 /* First time round, look for SMTP ports; second time round, look for
1637 SMTPS ports. For the first one of each, insert leading text. */
1638
1639 if (host_is_tls_on_connect_port(ipa->port) == (j > 0))
1640 {
1641 if (j == 0)
1642 {
1643 if (smtp_ports++ == 0)
1644 {
1645 memcpy(p, "SMTP on", 8);
1646 p += 7;
1647 }
1648 }
1649 else
1650 {
1651 if (smtps_ports++ == 0)
1652 {
1653 (void)sprintf(CS p, "%sSMTPS on",
1654 (smtp_ports == 0)? "":" and for ");
1655 while (*p != 0) p++;
1656 }
1657 }
1658
1659 /* Now the information about the port (and sometimes interface) */
1660
1661 if (ipa->address[0] == ':' && ipa->address[1] == 0)
1662 {
1663 if (ipa->next != NULL && ipa->next->address[0] == 0 &&
1664 ipa->next->port == ipa->port)
1665 {
1666 (void)sprintf(CS p, " port %d (IPv6 and IPv4)", ipa->port);
1667 ipa = ipa->next;
1668 }
1669 else if (ipa->v6_include_v4)
1670 (void)sprintf(CS p, " port %d (IPv6 with IPv4)", ipa->port);
1671 else
1672 (void)sprintf(CS p, " port %d (IPv6)", ipa->port);
1673 }
1674 else if (ipa->address[0] == 0)
1675 (void)sprintf(CS p, " port %d (IPv4)", ipa->port);
1676 else
1677 (void)sprintf(CS p, " [%s]:%d", ipa->address, ipa->port);
1678 while (*p != 0) p++;
1679 }
1680 }
1681
1682 if (ipa != NULL)
1683 {
1684 memcpy(p, " ...", 5);
1685 p += 4;
1686 }
1687 }
1688
1689 log_write(0, LOG_MAIN,
1690 "exim %s daemon started: pid=%d, %s, listening for %s",
1691 version_string, getpid(), qinfo, big_buffer);
1692 set_process_info("daemon(%s): %s, listening for %s", version_string, qinfo, big_buffer);
1693 }
1694
1695 else
1696 {
1697 log_write(0, LOG_MAIN,
1698 "exim %s daemon started: pid=%d, -q%s, not listening for SMTP",
1699 version_string, getpid(), readconf_printtime(queue_interval));
1700 set_process_info("daemon(%s): -q%s, not listening",
1701 version_string,
1702 readconf_printtime(queue_interval));
1703 }
1704
1705 /* Do any work it might be useful to amortize over our children
1706 (eg: compile regex) */
1707
1708 dns_pattern_init();
1709
1710 #ifdef WITH_CONTENT_SCAN
1711 malware_init();
1712 #endif
1713
1714 /* Close the log so it can be renamed and moved. In the few cases below where
1715 this long-running process writes to the log (always exceptional conditions), it
1716 closes the log afterwards, for the same reason. */
1717
1718 log_close_all();
1719
1720 DEBUG(D_any) debug_print_ids(US"daemon running with");
1721
1722 /* Any messages accepted via this route are going to be SMTP. */
1723
1724 smtp_input = TRUE;
1725
1726 /* Enter the never-ending loop... */
1727
1728 for (;;)
1729 {
1730 #if HAVE_IPV6
1731 struct sockaddr_in6 accepted;
1732 #else
1733 struct sockaddr_in accepted;
1734 #endif
1735
1736 EXIM_SOCKLEN_T len;
1737 pid_t pid;
1738
1739 /* This code is placed first in the loop, so that it gets obeyed at the
1740 start, before the first wait, for the queue-runner case, so that the first
1741 one can be started immediately.
1742
1743 The other option is that we have an inetd wait timeout specified to -bw. */
1744
1745 if (sigalrm_seen)
1746 {
1747 if (inetd_wait_timeout > 0)
1748 {
1749 time_t resignal_interval = inetd_wait_timeout;
1750
1751 if (last_connection_time == (time_t)0)
1752 {
1753 DEBUG(D_any)
1754 debug_printf("inetd wait timeout expired, but still not seen first message, ignoring\n");
1755 }
1756 else
1757 {
1758 time_t now = time(NULL);
1759 if (now == (time_t)-1)
1760 {
1761 DEBUG(D_any) debug_printf("failed to get time: %s\n", strerror(errno));
1762 }
1763 else
1764 {
1765 if ((now - last_connection_time) >= inetd_wait_timeout)
1766 {
1767 DEBUG(D_any)
1768 debug_printf("inetd wait timeout %d expired, ending daemon\n",
1769 inetd_wait_timeout);
1770 log_write(0, LOG_MAIN, "exim %s daemon terminating, inetd wait timeout reached.\n",
1771 version_string);
1772 exit(EXIT_SUCCESS);
1773 }
1774 else
1775 {
1776 resignal_interval -= (now - last_connection_time);
1777 }
1778 }
1779 }
1780
1781 sigalrm_seen = FALSE;
1782 alarm(resignal_interval);
1783 }
1784
1785 else
1786 {
1787 DEBUG(D_any) debug_printf("SIGALRM received\n");
1788
1789 /* Do a full queue run in a child process, if required, unless we already
1790 have enough queue runners on the go. If we are not running as root, a
1791 re-exec is required. */
1792
1793 if (queue_interval > 0 &&
1794 (local_queue_run_max <= 0 || queue_run_count < local_queue_run_max))
1795 {
1796 if ((pid = fork()) == 0)
1797 {
1798 int sk;
1799
1800 DEBUG(D_any) debug_printf("Starting queue-runner: pid %d\n",
1801 (int)getpid());
1802
1803 /* Disable debugging if it's required only for the daemon process. We
1804 leave the above message, because it ties up with the "child ended"
1805 debugging messages. */
1806
1807 if (debug_daemon) debug_selector = 0;
1808
1809 /* Close any open listening sockets in the child */
1810
1811 for (sk = 0; sk < listen_socket_count; sk++)
1812 (void)close(listen_sockets[sk]);
1813
1814 /* Reset SIGHUP and SIGCHLD in the child in both cases. */
1815
1816 signal(SIGHUP, SIG_DFL);
1817 signal(SIGCHLD, SIG_DFL);
1818
1819 /* Re-exec if privilege has been given up, unless deliver_drop_
1820 privilege is set. Reset SIGALRM before exec(). */
1821
1822 if (geteuid() != root_uid && !deliver_drop_privilege)
1823 {
1824 uschar opt[8];
1825 uschar *p = opt;
1826 uschar *extra[5];
1827 int extracount = 1;
1828
1829 signal(SIGALRM, SIG_DFL);
1830 *p++ = '-';
1831 *p++ = 'q';
1832 if (queue_2stage) *p++ = 'q';
1833 if (queue_run_first_delivery) *p++ = 'i';
1834 if (queue_run_force) *p++ = 'f';
1835 if (deliver_force_thaw) *p++ = 'f';
1836 if (queue_run_local) *p++ = 'l';
1837 *p = 0;
1838 if (queue_name)
1839 extra[0] = string_sprintf("%sG%s", opt, queue_name);
1840 else
1841 extra[0] = opt;
1842
1843 /* If -R or -S were on the original command line, ensure they get
1844 passed on. */
1845
1846 if (deliver_selectstring != NULL)
1847 {
1848 extra[extracount++] = deliver_selectstring_regex? US"-Rr" : US"-R";
1849 extra[extracount++] = deliver_selectstring;
1850 }
1851
1852 if (deliver_selectstring_sender != NULL)
1853 {
1854 extra[extracount++] = deliver_selectstring_sender_regex?
1855 US"-Sr" : US"-S";
1856 extra[extracount++] = deliver_selectstring_sender;
1857 }
1858
1859 /* Overlay this process with a new execution. */
1860
1861 (void)child_exec_exim(CEE_EXEC_PANIC, FALSE, NULL, TRUE, extracount,
1862 extra[0], extra[1], extra[2], extra[3], extra[4]);
1863
1864 /* Control never returns here. */
1865 }
1866
1867 /* No need to re-exec; SIGALRM remains set to the default handler */
1868
1869 queue_run(NULL, NULL, FALSE);
1870 _exit(EXIT_SUCCESS);
1871 }
1872
1873 if (pid < 0)
1874 {
1875 log_write(0, LOG_MAIN|LOG_PANIC, "daemon: fork of queue-runner "
1876 "process failed: %s", strerror(errno));
1877 log_close_all();
1878 }
1879 else
1880 {
1881 int i;
1882 for (i = 0; i < local_queue_run_max; ++i)
1883 if (queue_pid_slots[i] <= 0)
1884 {
1885 queue_pid_slots[i] = pid;
1886 queue_run_count++;
1887 break;
1888 }
1889 DEBUG(D_any) debug_printf("%d queue-runner process%s running\n",
1890 queue_run_count, (queue_run_count == 1)? "" : "es");
1891 }
1892 }
1893
1894 /* Reset the alarm clock */
1895
1896 sigalrm_seen = FALSE;
1897 alarm(queue_interval);
1898 }
1899
1900 } /* sigalrm_seen */
1901
1902
1903 /* Sleep till a connection happens if listening, and handle the connection if
1904 that is why we woke up. The FreeBSD operating system requires the use of
1905 select() before accept() because the latter function is not interrupted by
1906 a signal, and we want to wake up for SIGCHLD and SIGALRM signals. Some other
1907 OS do notice signals in accept() but it does no harm to have the select()
1908 in for all of them - and it won't then be a lurking problem for ports to
1909 new OS. In fact, the later addition of listening on specific interfaces only
1910 requires this way of working anyway. */
1911
1912 if (daemon_listen)
1913 {
1914 int sk, lcount, select_errno;
1915 int max_socket = 0;
1916 BOOL select_failed = FALSE;
1917 fd_set select_listen;
1918
1919 FD_ZERO(&select_listen);
1920 for (sk = 0; sk < listen_socket_count; sk++)
1921 {
1922 FD_SET(listen_sockets[sk], &select_listen);
1923 if (listen_sockets[sk] > max_socket) max_socket = listen_sockets[sk];
1924 }
1925
1926 DEBUG(D_any) debug_printf("Listening...\n");
1927
1928 /* In rare cases we may have had a SIGCHLD signal in the time between
1929 setting the handler (below) and getting back here. If so, pretend that the
1930 select() was interrupted so that we reap the child. This might still leave
1931 a small window when a SIGCHLD could get lost. However, since we use SIGCHLD
1932 only to do the reaping more quickly, it shouldn't result in anything other
1933 than a delay until something else causes a wake-up. */
1934
1935 if (sigchld_seen)
1936 {
1937 lcount = -1;
1938 errno = EINTR;
1939 }
1940 else
1941 {
1942 lcount = select(max_socket + 1, (SELECT_ARG2_TYPE *)&select_listen,
1943 NULL, NULL, NULL);
1944 }
1945
1946 if (lcount < 0)
1947 {
1948 select_failed = TRUE;
1949 lcount = 1;
1950 }
1951
1952 /* Clean up any subprocesses that may have terminated. We need to do this
1953 here so that smtp_accept_max_per_host works when a connection to that host
1954 has completed, and we are about to accept a new one. When this code was
1955 later in the sequence, a new connection could be rejected, even though an
1956 old one had just finished. Preserve the errno from any select() failure for
1957 the use of the common select/accept error processing below. */
1958
1959 select_errno = errno;
1960 handle_ending_processes();
1961 errno = select_errno;
1962
1963 /* Loop for all the sockets that are currently ready to go. If select
1964 actually failed, we have set the count to 1 and select_failed=TRUE, so as
1965 to use the common error code for select/accept below. */
1966
1967 while (lcount-- > 0)
1968 {
1969 int accept_socket = -1;
1970 if (!select_failed)
1971 {
1972 for (sk = 0; sk < listen_socket_count; sk++)
1973 {
1974 if (FD_ISSET(listen_sockets[sk], &select_listen))
1975 {
1976 len = sizeof(accepted);
1977 accept_socket = accept(listen_sockets[sk],
1978 (struct sockaddr *)&accepted, &len);
1979 FD_CLR(listen_sockets[sk], &select_listen);
1980 break;
1981 }
1982 }
1983 }
1984
1985 /* If select or accept has failed and this was not caused by an
1986 interruption, log the incident and try again. With asymmetric TCP/IP
1987 routing errors such as "No route to network" have been seen here. Also
1988 "connection reset by peer" has been seen. These cannot be classed as
1989 disastrous errors, but they could fill up a lot of log. The code in smail
1990 crashes the daemon after 10 successive failures of accept, on the grounds
1991 that some OS fail continuously. Exim originally followed suit, but this
1992 appears to have caused problems. Now it just keeps going, but instead of
1993 logging each error, it batches them up when they are continuous. */
1994
1995 if (accept_socket < 0 && errno != EINTR)
1996 {
1997 if (accept_retry_count == 0)
1998 {
1999 accept_retry_errno = errno;
2000 accept_retry_select_failed = select_failed;
2001 }
2002 else
2003 {
2004 if (errno != accept_retry_errno ||
2005 select_failed != accept_retry_select_failed ||
2006 accept_retry_count >= 50)
2007 {
2008 log_write(0, LOG_MAIN | ((accept_retry_count >= 50)? LOG_PANIC : 0),
2009 "%d %s() failure%s: %s",
2010 accept_retry_count,
2011 accept_retry_select_failed? "select" : "accept",
2012 (accept_retry_count == 1)? "" : "s",
2013 strerror(accept_retry_errno));
2014 log_close_all();
2015 accept_retry_count = 0;
2016 accept_retry_errno = errno;
2017 accept_retry_select_failed = select_failed;
2018 }
2019 }
2020 accept_retry_count++;
2021 }
2022
2023 else
2024 {
2025 if (accept_retry_count > 0)
2026 {
2027 log_write(0, LOG_MAIN, "%d %s() failure%s: %s",
2028 accept_retry_count,
2029 accept_retry_select_failed? "select" : "accept",
2030 (accept_retry_count == 1)? "" : "s",
2031 strerror(accept_retry_errno));
2032 log_close_all();
2033 accept_retry_count = 0;
2034 }
2035 }
2036
2037 /* If select/accept succeeded, deal with the connection. */
2038
2039 if (accept_socket >= 0)
2040 {
2041 if (inetd_wait_timeout)
2042 last_connection_time = time(NULL);
2043 handle_smtp_call(listen_sockets, listen_socket_count, accept_socket,
2044 (struct sockaddr *)&accepted);
2045 }
2046 }
2047 }
2048
2049 /* If not listening, then just sleep for the queue interval. If we woke
2050 up early the last time for some other signal, it won't matter because
2051 the alarm signal will wake at the right time. This code originally used
2052 sleep() but it turns out that on the FreeBSD system, sleep() is not inter-
2053 rupted by signals, so it wasn't waking up for SIGALRM or SIGCHLD. Luckily
2054 select() can be used as an interruptible sleep() on all versions of Unix. */
2055
2056 else
2057 {
2058 struct timeval tv;
2059 tv.tv_sec = queue_interval;
2060 tv.tv_usec = 0;
2061 select(0, NULL, NULL, NULL, &tv);
2062 handle_ending_processes();
2063 }
2064
2065 /* Re-enable the SIGCHLD handler if it has been run. It can't do it
2066 for itself, because it isn't doing the waiting itself. */
2067
2068 if (sigchld_seen)
2069 {
2070 sigchld_seen = FALSE;
2071 os_non_restarting_signal(SIGCHLD, main_sigchld_handler);
2072 }
2073
2074 /* Handle being woken by SIGHUP. We know at this point that the result
2075 of accept() has been dealt with, so we can re-exec exim safely, first
2076 closing the listening sockets so that they can be reused. Cancel any pending
2077 alarm in case it is just about to go off, and set SIGHUP to be ignored so
2078 that another HUP in quick succession doesn't clobber the new daemon before it
2079 gets going. All log files get closed by the close-on-exec flag; however, if
2080 the exec fails, we need to close the logs. */
2081
2082 if (sighup_seen)
2083 {
2084 int sk;
2085 log_write(0, LOG_MAIN, "pid %d: SIGHUP received: re-exec daemon",
2086 getpid());
2087 for (sk = 0; sk < listen_socket_count; sk++)
2088 (void)close(listen_sockets[sk]);
2089 alarm(0);
2090 signal(SIGHUP, SIG_IGN);
2091 sighup_argv[0] = exim_path;
2092 exim_nullstd();
2093 execv(CS exim_path, (char *const *)sighup_argv);
2094 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "pid %d: exec of %s failed: %s",
2095 getpid(), exim_path, strerror(errno));
2096 log_close_all();
2097 }
2098
2099 } /* End of main loop */
2100
2101 /* Control never reaches here */
2102 }
2103
2104 /* vi: aw ai sw=2
2105 */
2106 /* End of exim_daemon.c */