2d10387f6345fd21706cee946431ceeefe20c722
[exim.git] / src / src / daemon.c
1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
4
5 /* Copyright (c) University of Cambridge 1995 - 2015 */
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 if (list != NULL && verify_check_host(&list) == OK)
345 save_log_selector &= ~L_smtp_connection;
346 else
347 log_write(L_smtp_connection, LOG_MAIN, "SMTP connection from %s "
348 "(TCP/IP connection count = %d)", whofrom, smtp_accept_count + 1);
349 }
350
351 /* Now we can fork the accepting process; do a lookup tidy, just in case any
352 expansion above did a lookup. */
353
354 search_tidyup();
355 pid = fork();
356
357 /* Handle the child process */
358
359 if (pid == 0)
360 {
361 int i;
362 int queue_only_reason = 0;
363 int old_pool = store_pool;
364 int save_debug_selector = debug_selector;
365 BOOL local_queue_only;
366 BOOL session_local_queue_only;
367 #ifdef SA_NOCLDWAIT
368 struct sigaction act;
369 #endif
370
371 smtp_accept_count++; /* So that it includes this process */
372
373 /* May have been modified for the subprocess */
374
375 *log_selector = save_log_selector;
376
377 /* Get the local interface address into permanent store */
378
379 store_pool = POOL_PERM;
380 interface_address = string_copy(interface_address);
381 store_pool = old_pool;
382
383 /* Check for a tls-on-connect port */
384
385 if (host_is_tls_on_connect_port(interface_port)) tls_in.on_connect = TRUE;
386
387 /* Expand smtp_active_hostname if required. We do not do this any earlier,
388 because it may depend on the local interface address (indeed, that is most
389 likely what it depends on.) */
390
391 smtp_active_hostname = primary_hostname;
392 if (raw_active_hostname != NULL)
393 {
394 uschar *nah = expand_string(raw_active_hostname);
395 if (nah == NULL)
396 {
397 if (!expand_string_forcedfail)
398 {
399 log_write(0, LOG_MAIN|LOG_PANIC, "failed to expand \"%s\" "
400 "(smtp_active_hostname): %s", raw_active_hostname,
401 expand_string_message);
402 smtp_printf("421 Local configuration error; "
403 "please try again later.\r\n");
404 mac_smtp_fflush();
405 search_tidyup();
406 _exit(EXIT_FAILURE);
407 }
408 }
409 else if (nah[0] != 0) smtp_active_hostname = nah;
410 }
411
412 /* Initialize the queueing flags */
413
414 queue_check_only();
415 session_local_queue_only = queue_only;
416
417 /* Close the listening sockets, and set the SIGCHLD handler to SIG_IGN.
418 We also attempt to set things up so that children are automatically reaped,
419 but just in case this isn't available, there's a paranoid waitpid() in the
420 loop too (except for systems where we are sure it isn't needed). See the more
421 extensive comment before the reception loop in exim.c for a fuller
422 explanation of this logic. */
423
424 for (i = 0; i < listen_socket_count; i++) (void)close(listen_sockets[i]);
425
426 /* Set FD_CLOEXEC on the SMTP socket. We don't want any rogue child processes
427 to be able to communicate with them, under any circumstances. */
428 (void)fcntl(accept_socket, F_SETFD,
429 fcntl(accept_socket, F_GETFD) | FD_CLOEXEC);
430 (void)fcntl(dup_accept_socket, F_SETFD,
431 fcntl(dup_accept_socket, F_GETFD) | FD_CLOEXEC);
432
433 #ifdef SA_NOCLDWAIT
434 act.sa_handler = SIG_IGN;
435 sigemptyset(&(act.sa_mask));
436 act.sa_flags = SA_NOCLDWAIT;
437 sigaction(SIGCHLD, &act, NULL);
438 #else
439 signal(SIGCHLD, SIG_IGN);
440 #endif
441
442 /* Attempt to get an id from the sending machine via the RFC 1413
443 protocol. We do this in the sub-process in order not to hold up the
444 main process if there is any delay. Then set up the fullhost information
445 in case there is no HELO/EHLO.
446
447 If debugging is enabled only for the daemon, we must turn if off while
448 finding the id, but turn it on again afterwards so that information about the
449 incoming connection is output. */
450
451 if (debug_daemon) debug_selector = 0;
452 verify_get_ident(IDENT_PORT);
453 host_build_sender_fullhost();
454 debug_selector = save_debug_selector;
455
456 DEBUG(D_any)
457 debug_printf("Process %d is handling incoming connection from %s\n",
458 (int)getpid(), sender_fullhost);
459
460 /* Now disable debugging permanently if it's required only for the daemon
461 process. */
462
463 if (debug_daemon) debug_selector = 0;
464
465 /* If there are too many child processes for immediate delivery,
466 set the session_local_queue_only flag, which is initialized from the
467 configured value and may therefore already be TRUE. Leave logging
468 till later so it will have a message id attached. Note that there is no
469 possibility of re-calculating this per-message, because the value of
470 smtp_accept_count does not change in this subprocess. */
471
472 if (smtp_accept_queue > 0 && smtp_accept_count > smtp_accept_queue)
473 {
474 session_local_queue_only = TRUE;
475 queue_only_reason = 1;
476 }
477
478 /* Handle the start of the SMTP session, then loop, accepting incoming
479 messages from the SMTP connection. The end will come at the QUIT command,
480 when smtp_setup_msg() returns 0. A break in the connection causes the
481 process to die (see accept.c).
482
483 NOTE: We do *not* call smtp_log_no_mail() if smtp_start_session() fails,
484 because a log line has already been written for all its failure exists
485 (usually "connection refused: <reason>") and writing another one is
486 unnecessary clutter. */
487
488 if (!smtp_start_session())
489 {
490 mac_smtp_fflush();
491 search_tidyup();
492 _exit(EXIT_SUCCESS);
493 }
494
495 for (;;)
496 {
497 int rc;
498 message_id[0] = 0; /* Clear out any previous message_id */
499 reset_point = store_get(0); /* Save current store high water point */
500
501 DEBUG(D_any)
502 debug_printf("Process %d is ready for new message\n", (int)getpid());
503
504 /* Smtp_setup_msg() returns 0 on QUIT or if the call is from an
505 unacceptable host or if an ACL "drop" command was triggered, -1 on
506 connection lost, and +1 on validly reaching DATA. Receive_msg() almost
507 always returns TRUE when smtp_input is true; just retry if no message was
508 accepted (can happen for invalid message parameters). However, it can yield
509 FALSE if the connection was forcibly dropped by the DATA ACL. */
510
511 if ((rc = smtp_setup_msg()) > 0)
512 {
513 BOOL ok = receive_msg(FALSE);
514 search_tidyup(); /* Close cached databases */
515 if (!ok) /* Connection was dropped */
516 {
517 mac_smtp_fflush();
518 smtp_log_no_mail(); /* Log no mail if configured */
519 _exit(EXIT_SUCCESS);
520 }
521 if (message_id[0] == 0) continue; /* No message was accepted */
522 }
523 else
524 {
525 mac_smtp_fflush();
526 search_tidyup();
527 smtp_log_no_mail(); /* Log no mail if configured */
528 _exit((rc == 0)? EXIT_SUCCESS : EXIT_FAILURE);
529 }
530
531 /* Show the recipients when debugging */
532
533 DEBUG(D_receive)
534 {
535 int i;
536 if (sender_address != NULL)
537 debug_printf("Sender: %s\n", sender_address);
538 if (recipients_list != NULL)
539 {
540 debug_printf("Recipients:\n");
541 for (i = 0; i < recipients_count; i++)
542 debug_printf(" %s\n", recipients_list[i].address);
543 }
544 }
545
546 /* A message has been accepted. Clean up any previous delivery processes
547 that have completed and are defunct, on systems where they don't go away
548 by themselves (see comments when setting SIG_IGN above). On such systems
549 (if any) these delivery processes hang around after termination until
550 the next message is received. */
551
552 #ifndef SIG_IGN_WORKS
553 while (waitpid(-1, NULL, WNOHANG) > 0);
554 #endif
555
556 /* Reclaim up the store used in accepting this message */
557
558 store_reset(reset_point);
559
560 /* If queue_only is set or if there are too many incoming connections in
561 existence, session_local_queue_only will be TRUE. If it is not, check
562 whether we have received too many messages in this session for immediate
563 delivery. */
564
565 if (!session_local_queue_only &&
566 smtp_accept_queue_per_connection > 0 &&
567 receive_messagecount > smtp_accept_queue_per_connection)
568 {
569 session_local_queue_only = TRUE;
570 queue_only_reason = 2;
571 }
572
573 /* Initialize local_queue_only from session_local_queue_only. If it is not
574 true, and queue_only_load is set, check that the load average is below it.
575 If local_queue_only is set by this means, we also set if for the session if
576 queue_only_load_latch is true (the default). This means that, once set,
577 local_queue_only remains set for any subsequent messages on the same SMTP
578 connection. This is a deliberate choice; even though the load average may
579 fall, it doesn't seem right to deliver later messages on the same call when
580 not delivering earlier ones. However, the are special circumstances such as
581 very long-lived connections from scanning appliances where this is not the
582 best strategy. In such cases, queue_only_load_latch should be set false. */
583
584 local_queue_only = session_local_queue_only;
585 if (!local_queue_only && queue_only_load >= 0)
586 {
587 local_queue_only = (load_average = OS_GETLOADAVG()) > queue_only_load;
588 if (local_queue_only)
589 {
590 queue_only_reason = 3;
591 if (queue_only_load_latch) session_local_queue_only = TRUE;
592 }
593 }
594
595 /* Log the queueing here, when it will get a message id attached, but
596 not if queue_only is set (case 0). */
597
598 if (local_queue_only) switch(queue_only_reason)
599 {
600 case 1:
601 log_write(L_delay_delivery,
602 LOG_MAIN, "no immediate delivery: too many connections "
603 "(%d, max %d)", smtp_accept_count, smtp_accept_queue);
604 break;
605
606 case 2:
607 log_write(L_delay_delivery,
608 LOG_MAIN, "no immediate delivery: more than %d messages "
609 "received in one connection", smtp_accept_queue_per_connection);
610 break;
611
612 case 3:
613 log_write(L_delay_delivery,
614 LOG_MAIN, "no immediate delivery: load average %.2f",
615 (double)load_average/1000.0);
616 break;
617 }
618
619 /* If a delivery attempt is required, spin off a new process to handle it.
620 If we are not root, we have to re-exec exim unless deliveries are being
621 done unprivileged. */
622
623 else if (!queue_only_policy && !deliver_freeze)
624 {
625 pid_t dpid;
626
627 /* Before forking, ensure that the C output buffer is flushed. Otherwise
628 anything that it in it will get duplicated, leading to duplicate copies
629 of the pending output. */
630
631 mac_smtp_fflush();
632
633 if ((dpid = fork()) == 0)
634 {
635 (void)fclose(smtp_in);
636 (void)fclose(smtp_out);
637
638 /* Don't ever molest the parent's SSL connection, but do clean up
639 the data structures if necessary. */
640
641 #ifdef SUPPORT_TLS
642 tls_close(TRUE, FALSE);
643 #endif
644
645 /* Reset SIGHUP and SIGCHLD in the child in both cases. */
646
647 signal(SIGHUP, SIG_DFL);
648 signal(SIGCHLD, SIG_DFL);
649
650 if (geteuid() != root_uid && !deliver_drop_privilege)
651 {
652 signal(SIGALRM, SIG_DFL);
653 (void)child_exec_exim(CEE_EXEC_PANIC, FALSE, NULL, FALSE, 2, US"-Mc",
654 message_id);
655 /* Control does not return here. */
656 }
657
658 /* No need to re-exec; SIGALRM remains set to the default handler */
659
660 (void)deliver_message(message_id, FALSE, FALSE);
661 search_tidyup();
662 _exit(EXIT_SUCCESS);
663 }
664
665 if (dpid > 0)
666 {
667 DEBUG(D_any) debug_printf("forked delivery process %d\n", (int)dpid);
668 }
669 else
670 {
671 log_write(0, LOG_MAIN|LOG_PANIC, "daemon: delivery process fork "
672 "failed: %s", strerror(errno));
673 }
674 }
675 }
676 }
677
678
679 /* Carrying on in the parent daemon process... Can't do much if the fork
680 failed. Otherwise, keep count of the number of accepting processes and
681 remember the pid for ticking off when the child completes. */
682
683 if (pid < 0)
684 {
685 never_error(US"daemon: accept process fork failed", US"Fork failed", errno);
686 }
687 else
688 {
689 int i;
690 for (i = 0; i < smtp_accept_max; ++i)
691 {
692 if (smtp_slots[i].pid <= 0)
693 {
694 smtp_slots[i].pid = pid;
695 if (smtp_accept_max_per_host != NULL)
696 smtp_slots[i].host_address = string_copy_malloc(sender_host_address);
697 smtp_accept_count++;
698 break;
699 }
700 }
701 DEBUG(D_any) debug_printf("%d SMTP accept process%s running\n",
702 smtp_accept_count, (smtp_accept_count == 1)? "" : "es");
703 }
704
705 /* Get here via goto in error cases */
706
707 ERROR_RETURN:
708
709 /* Close the streams associated with the socket which will also close the
710 socket fds in this process. We can't do anything if fclose() fails, but
711 logging brings it to someone's attention. However, "connection reset by peer"
712 isn't really a problem, so skip that one. On Solaris, a dropped connection can
713 manifest itself as a broken pipe, so drop that one too. If the streams don't
714 exist, something went wrong while setting things up. Make sure the socket
715 descriptors are closed, in order to drop the connection. */
716
717 if (smtp_out != NULL)
718 {
719 if (fclose(smtp_out) != 0 && errno != ECONNRESET && errno != EPIPE)
720 log_write(0, LOG_MAIN|LOG_PANIC, "daemon: fclose(smtp_out) failed: %s",
721 strerror(errno));
722 smtp_out = NULL;
723 }
724 else (void)close(accept_socket);
725
726 if (smtp_in != NULL)
727 {
728 if (fclose(smtp_in) != 0 && errno != ECONNRESET && errno != EPIPE)
729 log_write(0, LOG_MAIN|LOG_PANIC, "daemon: fclose(smtp_in) failed: %s",
730 strerror(errno));
731 smtp_in = NULL;
732 }
733 else (void)close(dup_accept_socket);
734
735 /* Release any store used in this process, including the store used for holding
736 the incoming host address and an expanded active_hostname. */
737
738 store_reset(reset_point);
739 sender_host_address = NULL;
740 }
741
742
743
744
745 /*************************************************
746 * Check wildcard listen special cases *
747 *************************************************/
748
749 /* This function is used when binding and listening on lists of addresses and
750 ports. It tests for special cases of wildcard listening, when IPv4 and IPv6
751 sockets may interact in different ways in different operating systems. It is
752 passed an error number, the list of listening addresses, and the current
753 address. Two checks are available: for a previous wildcard IPv6 address, or for
754 a following wildcard IPv4 address, in both cases on the same port.
755
756 In practice, pairs of wildcard addresses should be adjacent in the address list
757 because they are sorted that way below.
758
759 Arguments:
760 eno the error number
761 addresses the list of addresses
762 ipa the current IP address
763 back if TRUE, check for previous wildcard IPv6 address
764 if FALSE, check for a following wildcard IPv4 address
765
766 Returns: TRUE or FALSE
767 */
768
769 static BOOL
770 check_special_case(int eno, ip_address_item *addresses, ip_address_item *ipa,
771 BOOL back)
772 {
773 ip_address_item *ipa2;
774
775 /* For the "back" case, if the failure was "address in use" for a wildcard IPv4
776 address, seek a previous IPv6 wildcard address on the same port. As it is
777 previous, it must have been successfully bound and be listening. Flag it as a
778 "6 including 4" listener. */
779
780 if (back)
781 {
782 if (eno != EADDRINUSE || ipa->address[0] != 0) return FALSE;
783 for (ipa2 = addresses; ipa2 != ipa; ipa2 = ipa2->next)
784 {
785 if (ipa2->address[1] == 0 && ipa2->port == ipa->port)
786 {
787 ipa2->v6_include_v4 = TRUE;
788 return TRUE;
789 }
790 }
791 }
792
793 /* For the "forward" case, if the current address is a wildcard IPv6 address,
794 we seek a following wildcard IPv4 address on the same port. */
795
796 else
797 {
798 if (ipa->address[0] != ':' || ipa->address[1] != 0) return FALSE;
799 for (ipa2 = ipa->next; ipa2 != NULL; ipa2 = ipa2->next)
800 if (ipa2->address[0] == 0 && ipa->port == ipa2->port) return TRUE;
801 }
802
803 return FALSE;
804 }
805
806
807
808
809 /*************************************************
810 * Handle terminating subprocesses *
811 *************************************************/
812
813 /* Handle the termination of child processes. Theoretically, this need be done
814 only when sigchld_seen is TRUE, but rumour has it that some systems lose
815 SIGCHLD signals at busy times, so to be on the safe side, this function is
816 called each time round. It shouldn't be too expensive.
817
818 Arguments: none
819 Returns: nothing
820 */
821
822 static void
823 handle_ending_processes(void)
824 {
825 int status;
826 pid_t pid;
827
828 while ((pid = waitpid(-1, &status, WNOHANG)) > 0)
829 {
830 int i;
831 DEBUG(D_any)
832 {
833 debug_printf("child %d ended: status=0x%x\n", (int)pid, status);
834 #ifdef WCOREDUMP
835 if (WIFEXITED(status))
836 debug_printf(" normal exit, %d\n", WEXITSTATUS(status));
837 else if (WIFSIGNALED(status))
838 debug_printf(" signal exit, signal %d%s\n", WTERMSIG(status),
839 WCOREDUMP(status) ? " (core dumped)" : "");
840 #endif
841 }
842
843 /* If it's a listening daemon for which we are keeping track of individual
844 subprocesses, deal with an accepting process that has terminated. */
845
846 if (smtp_slots != NULL)
847 {
848 for (i = 0; i < smtp_accept_max; i++)
849 {
850 if (smtp_slots[i].pid == pid)
851 {
852 if (smtp_slots[i].host_address != NULL)
853 store_free(smtp_slots[i].host_address);
854 smtp_slots[i] = empty_smtp_slot;
855 if (--smtp_accept_count < 0) smtp_accept_count = 0;
856 DEBUG(D_any) debug_printf("%d SMTP accept process%s now running\n",
857 smtp_accept_count, (smtp_accept_count == 1)? "" : "es");
858 break;
859 }
860 }
861 if (i < smtp_accept_max) continue; /* Found an accepting process */
862 }
863
864 /* If it wasn't an accepting process, see if it was a queue-runner
865 process that we are tracking. */
866
867 if (queue_pid_slots != NULL)
868 {
869 for (i = 0; i < queue_run_max; i++)
870 {
871 if (queue_pid_slots[i] == pid)
872 {
873 queue_pid_slots[i] = 0;
874 if (--queue_run_count < 0) queue_run_count = 0;
875 DEBUG(D_any) debug_printf("%d queue-runner process%s now running\n",
876 queue_run_count, (queue_run_count == 1)? "" : "es");
877 break;
878 }
879 }
880 }
881 }
882 }
883
884
885
886 /*************************************************
887 * Exim Daemon Mainline *
888 *************************************************/
889
890 /* The daemon can do two jobs, either of which is optional:
891
892 (1) Listens for incoming SMTP calls and spawns off a sub-process to handle
893 each one. This is requested by the -bd option, with -oX specifying the SMTP
894 port on which to listen (for testing).
895
896 (2) Spawns a queue-running process every so often. This is controlled by the
897 -q option with a an interval time. (If no time is given, a single queue run
898 is done from the main function, and control doesn't get here.)
899
900 Root privilege is required in order to attach to port 25. Some systems require
901 it when calling socket() rather than bind(). To cope with all cases, we run as
902 root for both socket() and bind(). Some systems also require root in order to
903 write to the pid file directory. This function must therefore be called as root
904 if it is to work properly in all circumstances. Once the socket is bound and
905 the pid file written, root privilege is given up if there is an exim uid.
906
907 There are no arguments to this function, and it never returns. */
908
909 void
910 daemon_go(void)
911 {
912 struct passwd *pw;
913 int *listen_sockets = NULL;
914 int listen_socket_count = 0;
915 ip_address_item *addresses = NULL;
916 time_t last_connection_time = (time_t)0;
917
918 /* If any debugging options are set, turn on the D_pid bit so that all
919 debugging lines get the pid added. */
920
921 DEBUG(D_any|D_v) debug_selector |= D_pid;
922
923 if (inetd_wait_mode)
924 {
925 int on = 1;
926
927 listen_socket_count = 1;
928 listen_sockets = store_get(sizeof(int *));
929 (void) close(3);
930 if (dup2(0, 3) == -1)
931 {
932 log_write(0, LOG_MAIN|LOG_PANIC_DIE,
933 "failed to dup inetd socket safely away: %s", strerror(errno));
934 }
935 listen_sockets[0] = 3;
936 (void) close(0);
937 (void) close(1);
938 (void) close(2);
939 exim_nullstd();
940
941 if (debug_file == stderr)
942 {
943 /* need a call to log_write before call to open debug_file, so that
944 log.c:file_path has been initialised. This is unfortunate. */
945 log_write(0, LOG_MAIN, "debugging Exim in inetd wait mode starting");
946
947 fclose(debug_file);
948 debug_file = NULL;
949 exim_nullstd(); /* re-open fd2 after we just closed it again */
950 debug_logging_activate(US"-wait", NULL);
951 }
952
953 DEBUG(D_any) debug_printf("running in inetd wait mode\n");
954
955 /* As per below, when creating sockets ourselves, we handle tcp_nodelay for
956 our own buffering; we assume though that inetd set the socket REUSEADDR. */
957
958 if (tcp_nodelay) setsockopt(3, IPPROTO_TCP, TCP_NODELAY,
959 (uschar *)(&on), sizeof(on));
960 }
961
962
963 if (inetd_wait_mode || daemon_listen)
964 {
965 /* If any option requiring a load average to be available during the
966 reception of a message is set, call os_getloadavg() while we are root
967 for those OS for which this is necessary the first time it is called (in
968 order to perform an "open" on the kernel memory file). */
969
970 #ifdef LOAD_AVG_NEEDS_ROOT
971 if (queue_only_load >= 0 || smtp_load_reserve >= 0 ||
972 (deliver_queue_load_max >= 0 && deliver_drop_privilege))
973 (void)os_getloadavg();
974 #endif
975 }
976
977
978 /* Do the preparation for setting up a listener on one or more interfaces, and
979 possible on various ports. This is controlled by the combination of
980 local_interfaces (which can set IP addresses and ports) and daemon_smtp_port
981 (which is a list of default ports to use for those items in local_interfaces
982 that do not specify a port). The -oX command line option can be used to
983 override one or both of these options.
984
985 If local_interfaces is not set, the default is to listen on all interfaces.
986 When it is set, it can include "all IPvx interfaces" as an item. This is useful
987 when different ports are in use.
988
989 It turns out that listening on all interfaces is messy in an IPv6 world,
990 because several different implementation approaches have been taken. This code
991 is now supposed to work with all of them. The point of difference is whether an
992 IPv6 socket that is listening on all interfaces will receive incoming IPv4
993 calls or not. We also have to cope with the case when IPv6 libraries exist, but
994 there is no IPv6 support in the kernel.
995
996 . On Solaris, an IPv6 socket will accept IPv4 calls, and give them as mapped
997 addresses. However, if an IPv4 socket is also listening on all interfaces,
998 calls are directed to the appropriate socket.
999
1000 . On (some versions of) Linux, an IPv6 socket will accept IPv4 calls, and
1001 give them as mapped addresses, but an attempt also to listen on an IPv4
1002 socket on all interfaces causes an error.
1003
1004 . On OpenBSD, an IPv6 socket will not accept IPv4 calls. You have to set up
1005 two sockets if you want to accept both kinds of call.
1006
1007 . FreeBSD is like OpenBSD, but it has the IPV6_V6ONLY socket option, which
1008 can be turned off, to make it behave like the versions of Linux described
1009 above.
1010
1011 . I heard a report that the USAGI IPv6 stack for Linux has implemented
1012 IPV6_V6ONLY.
1013
1014 So, what we do when IPv6 is supported is as follows:
1015
1016 (1) After it is set up, the list of interfaces is scanned for wildcard
1017 addresses. If an IPv6 and an IPv4 wildcard are both found for the same
1018 port, the list is re-arranged so that they are together, with the IPv6
1019 wildcard first.
1020
1021 (2) If the creation of a wildcard IPv6 socket fails, we just log the error and
1022 carry on if an IPv4 wildcard socket for the same port follows later in the
1023 list. This allows Exim to carry on in the case when the kernel has no IPv6
1024 support.
1025
1026 (3) Having created an IPv6 wildcard socket, we try to set IPV6_V6ONLY if that
1027 option is defined. However, if setting fails, carry on regardless (but log
1028 the incident).
1029
1030 (4) If binding or listening on an IPv6 wildcard socket fails, it is a serious
1031 error.
1032
1033 (5) If binding or listening on an IPv4 wildcard socket fails with the error
1034 EADDRINUSE, and a previous interface was an IPv6 wildcard for the same
1035 port (which must have succeeded or we wouldn't have got this far), we
1036 assume we are in the situation where just a single socket is permitted,
1037 and ignore the error.
1038
1039 Phew!
1040
1041 The preparation code decodes options and sets up the relevant data. We do this
1042 first, so that we can return non-zero if there are any syntax errors, and also
1043 write to stderr. */
1044
1045 if (daemon_listen && !inetd_wait_mode)
1046 {
1047 int *default_smtp_port;
1048 int sep;
1049 int pct = 0;
1050 uschar *s;
1051 const uschar * list;
1052 uschar *local_iface_source = US"local_interfaces";
1053 ip_address_item *ipa;
1054 ip_address_item **pipa;
1055
1056 /* If -oX was used, disable the writing of a pid file unless -oP was
1057 explicitly used to force it. Then scan the string given to -oX. Any items
1058 that contain neither a dot nor a colon are used to override daemon_smtp_port.
1059 Any other items are used to override local_interfaces. */
1060
1061 if (override_local_interfaces != NULL)
1062 {
1063 uschar *new_smtp_port = NULL;
1064 uschar *new_local_interfaces = NULL;
1065 int portsize = 0;
1066 int portptr = 0;
1067 int ifacesize = 0;
1068 int ifaceptr = 0;
1069
1070 if (override_pid_file_path == NULL) write_pid = FALSE;
1071
1072 list = override_local_interfaces;
1073 sep = 0;
1074 while ((s = string_nextinlist(&list, &sep, big_buffer, big_buffer_size)))
1075 {
1076 uschar joinstr[4];
1077 uschar **ptr;
1078 int *sizeptr;
1079 int *ptrptr;
1080
1081 if (Ustrpbrk(s, ".:") == NULL)
1082 {
1083 ptr = &new_smtp_port;
1084 sizeptr = &portsize;
1085 ptrptr = &portptr;
1086 }
1087 else
1088 {
1089 ptr = &new_local_interfaces;
1090 sizeptr = &ifacesize;
1091 ptrptr = &ifaceptr;
1092 }
1093
1094 if (*ptr == NULL)
1095 {
1096 joinstr[0] = sep;
1097 joinstr[1] = ' ';
1098 *ptr = string_cat(*ptr, sizeptr, ptrptr, US"<", 1);
1099 }
1100
1101 *ptr = string_cat(*ptr, sizeptr, ptrptr, joinstr, 2);
1102 *ptr = string_cat(*ptr, sizeptr, ptrptr, s, Ustrlen(s));
1103 }
1104
1105 if (new_smtp_port != NULL)
1106 {
1107 new_smtp_port[portptr] = 0;
1108 daemon_smtp_port = new_smtp_port;
1109 DEBUG(D_any) debug_printf("daemon_smtp_port overridden by -oX:\n %s\n",
1110 daemon_smtp_port);
1111 }
1112
1113 if (new_local_interfaces != NULL)
1114 {
1115 new_local_interfaces[ifaceptr] = 0;
1116 local_interfaces = new_local_interfaces;
1117 local_iface_source = US"-oX data";
1118 DEBUG(D_any) debug_printf("local_interfaces overridden by -oX:\n %s\n",
1119 local_interfaces);
1120 }
1121 }
1122
1123 /* Create a list of default SMTP ports, to be used if local_interfaces
1124 contains entries without explict ports. First count the number of ports, then
1125 build a translated list in a vector. */
1126
1127 list = daemon_smtp_port;
1128 sep = 0;
1129 while ((s = string_nextinlist(&list, &sep, big_buffer, big_buffer_size)))
1130 pct++;
1131 default_smtp_port = store_get((pct+1) * sizeof(int));
1132 list = daemon_smtp_port;
1133 sep = 0;
1134 for (pct = 0;
1135 (s = string_nextinlist(&list, &sep, big_buffer, big_buffer_size));
1136 pct++)
1137 {
1138 if (isdigit(*s))
1139 {
1140 uschar *end;
1141 default_smtp_port[pct] = Ustrtol(s, &end, 0);
1142 if (end != s + Ustrlen(s))
1143 log_write(0, LOG_PANIC_DIE|LOG_CONFIG, "invalid SMTP port: %s", s);
1144 }
1145 else
1146 {
1147 struct servent *smtp_service = getservbyname(CS s, "tcp");
1148 if (!smtp_service)
1149 log_write(0, LOG_PANIC_DIE|LOG_CONFIG, "TCP port \"%s\" not found", s);
1150 default_smtp_port[pct] = ntohs(smtp_service->s_port);
1151 }
1152 }
1153 default_smtp_port[pct] = 0;
1154
1155 /* Check the list of TLS-on-connect ports and do name lookups if needed */
1156
1157 list = tls_in.on_connect_ports;
1158 sep = 0;
1159 while ((s = string_nextinlist(&list, &sep, big_buffer, big_buffer_size)))
1160 if (!isdigit(*s))
1161 {
1162 list = tls_in.on_connect_ports;
1163 tls_in.on_connect_ports = NULL;
1164 sep = 0;
1165 while ((s = string_nextinlist(&list, &sep, big_buffer, big_buffer_size)))
1166 {
1167 if (!isdigit(*s))
1168 {
1169 struct servent *smtp_service = getservbyname(CS s, "tcp");
1170 if (!smtp_service)
1171 log_write(0, LOG_PANIC_DIE|LOG_CONFIG, "TCP port \"%s\" not found", s);
1172 s= string_sprintf("%d", (int)ntohs(smtp_service->s_port));
1173 }
1174 tls_in.on_connect_ports = string_append_listele(tls_in.on_connect_ports,
1175 ':', s);
1176 }
1177 break;
1178 }
1179
1180 /* Create the list of local interfaces, possibly with ports included. This
1181 list may contain references to 0.0.0.0 and ::0 as wildcards. These special
1182 values are converted below. */
1183
1184 addresses = host_build_ifacelist(local_interfaces, local_iface_source);
1185
1186 /* In the list of IP addresses, convert 0.0.0.0 into an empty string, and ::0
1187 into the string ":". We use these to recognize wildcards in IPv4 and IPv6. In
1188 fact, many IP stacks recognize 0.0.0.0 and ::0 and handle them as wildcards
1189 anyway, but we need to know which are the wildcard addresses, and the shorter
1190 strings are neater.
1191
1192 In the same scan, fill in missing port numbers from the default list. When
1193 there is more than one item in the list, extra items are created. */
1194
1195 for (ipa = addresses; ipa != NULL; ipa = ipa->next)
1196 {
1197 int i;
1198
1199 if (Ustrcmp(ipa->address, "0.0.0.0") == 0) ipa->address[0] = 0;
1200 else if (Ustrcmp(ipa->address, "::0") == 0)
1201 {
1202 ipa->address[0] = ':';
1203 ipa->address[1] = 0;
1204 }
1205
1206 if (ipa->port > 0) continue;
1207
1208 if (daemon_smtp_port[0] <= 0)
1209 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "no port specified for interface "
1210 "%s and daemon_smtp_port is unset; cannot start daemon",
1211 (ipa->address[0] == 0)? US"\"all IPv4\"" :
1212 (ipa->address[1] == 0)? US"\"all IPv6\"" : ipa->address);
1213 ipa->port = default_smtp_port[0];
1214 for (i = 1; default_smtp_port[i] > 0; i++)
1215 {
1216 ip_address_item *new = store_get(sizeof(ip_address_item));
1217 memcpy(new->address, ipa->address, Ustrlen(ipa->address) + 1);
1218 new->port = default_smtp_port[i];
1219 new->next = ipa->next;
1220 ipa->next = new;
1221 ipa = new;
1222 }
1223 }
1224
1225 /* Scan the list of addresses for wildcards. If we find an IPv4 and an IPv6
1226 wildcard for the same port, ensure that (a) they are together and (b) the
1227 IPv6 address comes first. This makes handling the messy features easier, and
1228 also simplifies the construction of the "daemon started" log line. */
1229
1230 pipa = &addresses;
1231 for (ipa = addresses; ipa != NULL; pipa = &(ipa->next), ipa = ipa->next)
1232 {
1233 ip_address_item *ipa2;
1234
1235 /* Handle an IPv4 wildcard */
1236
1237 if (ipa->address[0] == 0)
1238 {
1239 for (ipa2 = ipa; ipa2->next != NULL; ipa2 = ipa2->next)
1240 {
1241 ip_address_item *ipa3 = ipa2->next;
1242 if (ipa3->address[0] == ':' &&
1243 ipa3->address[1] == 0 &&
1244 ipa3->port == ipa->port)
1245 {
1246 ipa2->next = ipa3->next;
1247 ipa3->next = ipa;
1248 *pipa = ipa3;
1249 break;
1250 }
1251 }
1252 }
1253
1254 /* Handle an IPv6 wildcard. */
1255
1256 else if (ipa->address[0] == ':' && ipa->address[1] == 0)
1257 {
1258 for (ipa2 = ipa; ipa2->next != NULL; ipa2 = ipa2->next)
1259 {
1260 ip_address_item *ipa3 = ipa2->next;
1261 if (ipa3->address[0] == 0 && ipa3->port == ipa->port)
1262 {
1263 ipa2->next = ipa3->next;
1264 ipa3->next = ipa->next;
1265 ipa->next = ipa3;
1266 ipa = ipa3;
1267 break;
1268 }
1269 }
1270 }
1271 }
1272
1273 /* Get a vector to remember all the sockets in */
1274
1275 for (ipa = addresses; ipa != NULL; ipa = ipa->next)
1276 listen_socket_count++;
1277 listen_sockets = store_get(sizeof(int *) * listen_socket_count);
1278
1279 } /* daemon_listen but not inetd_wait_mode */
1280
1281 if (daemon_listen)
1282 {
1283
1284 /* Do a sanity check on the max connects value just to save us from getting
1285 a huge amount of store. */
1286
1287 if (smtp_accept_max > 4095) smtp_accept_max = 4096;
1288
1289 /* There's no point setting smtp_accept_queue unless it is less than the max
1290 connects limit. The configuration reader ensures that the max is set if the
1291 queue-only option is set. */
1292
1293 if (smtp_accept_queue > smtp_accept_max) smtp_accept_queue = 0;
1294
1295 /* Get somewhere to keep the list of SMTP accepting pids if we are keeping
1296 track of them for total number and queue/host limits. */
1297
1298 if (smtp_accept_max > 0)
1299 {
1300 int i;
1301 smtp_slots = store_get(smtp_accept_max * sizeof(smtp_slot));
1302 for (i = 0; i < smtp_accept_max; i++) smtp_slots[i] = empty_smtp_slot;
1303 }
1304 }
1305
1306 /* The variable background_daemon is always false when debugging, but
1307 can also be forced false in order to keep a non-debugging daemon in the
1308 foreground. If background_daemon is true, close all open file descriptors that
1309 we know about, but then re-open stdin, stdout, and stderr to /dev/null. Also
1310 do this for inetd_wait mode.
1311
1312 This is protection against any called functions (in libraries, or in
1313 Perl, or whatever) that think they can write to stderr (or stdout). Before this
1314 was added, it was quite likely that an SMTP connection would use one of these
1315 file descriptors, in which case writing random stuff to it caused chaos.
1316
1317 Then disconnect from the controlling terminal, Most modern Unixes seem to have
1318 setsid() for getting rid of the controlling terminal. For any OS that doesn't,
1319 setsid() can be #defined as a no-op, or as something else. */
1320
1321 if (background_daemon || inetd_wait_mode)
1322 {
1323 log_close_all(); /* Just in case anything was logged earlier */
1324 search_tidyup(); /* Just in case any were used in reading the config. */
1325 (void)close(0); /* Get rid of stdin/stdout/stderr */
1326 (void)close(1);
1327 (void)close(2);
1328 exim_nullstd(); /* Connect stdin/stdout/stderr to /dev/null */
1329 log_stderr = NULL; /* So no attempt to copy paniclog output */
1330 }
1331
1332 if (background_daemon)
1333 {
1334 /* If the parent process of this one has pid == 1, we are re-initializing the
1335 daemon as the result of a SIGHUP. In this case, there is no need to do
1336 anything, because the controlling terminal has long gone. Otherwise, fork, in
1337 case current process is a process group leader (see 'man setsid' for an
1338 explanation) before calling setsid(). */
1339
1340 if (getppid() != 1)
1341 {
1342 pid_t pid = fork();
1343 if (pid < 0) log_write(0, LOG_MAIN|LOG_PANIC_DIE,
1344 "fork() failed when starting daemon: %s", strerror(errno));
1345 if (pid > 0) exit(EXIT_SUCCESS); /* in parent process, just exit */
1346 (void)setsid(); /* release controlling terminal */
1347 }
1348 }
1349
1350 /* We are now in the disconnected, daemon process (unless debugging). Set up
1351 the listening sockets if required. */
1352
1353 if (daemon_listen && !inetd_wait_mode)
1354 {
1355 int sk;
1356 int on = 1;
1357 ip_address_item *ipa;
1358
1359 /* For each IP address, create a socket, bind it to the appropriate port, and
1360 start listening. See comments above about IPv6 sockets that may or may not
1361 accept IPv4 calls when listening on all interfaces. We also have to cope with
1362 the case of a system with IPv6 libraries, but no IPv6 support in the kernel.
1363 listening, provided a wildcard IPv4 socket for the same port follows. */
1364
1365 for (ipa = addresses, sk = 0; sk < listen_socket_count; ipa = ipa->next, sk++)
1366 {
1367 BOOL wildcard;
1368 ip_address_item *ipa2;
1369 int af;
1370
1371 if (Ustrchr(ipa->address, ':') != NULL)
1372 {
1373 af = AF_INET6;
1374 wildcard = ipa->address[1] == 0;
1375 }
1376 else
1377 {
1378 af = AF_INET;
1379 wildcard = ipa->address[0] == 0;
1380 }
1381
1382 listen_sockets[sk] = ip_socket(SOCK_STREAM, af);
1383 if (listen_sockets[sk] < 0)
1384 {
1385 if (check_special_case(0, addresses, ipa, FALSE))
1386 {
1387 log_write(0, LOG_MAIN, "Failed to create IPv6 socket for wildcard "
1388 "listening (%s): will use IPv4", strerror(errno));
1389 goto SKIP_SOCKET;
1390 }
1391 log_write(0, LOG_PANIC_DIE, "IPv%c socket creation failed: %s",
1392 (af == AF_INET6)? '6' : '4', strerror(errno));
1393 }
1394
1395 /* If this is an IPv6 wildcard socket, set IPV6_V6ONLY if that option is
1396 available. Just log failure (can get protocol not available, just like
1397 socket creation can). */
1398
1399 #ifdef IPV6_V6ONLY
1400 if (af == AF_INET6 && wildcard &&
1401 setsockopt(listen_sockets[sk], IPPROTO_IPV6, IPV6_V6ONLY, (char *)(&on),
1402 sizeof(on)) < 0)
1403 log_write(0, LOG_MAIN, "Setting IPV6_V6ONLY on daemon's IPv6 wildcard "
1404 "socket failed (%s): carrying on without it", strerror(errno));
1405 #endif /* IPV6_V6ONLY */
1406
1407 /* Set SO_REUSEADDR so that the daemon can be restarted while a connection
1408 is being handled. Without this, a connection will prevent reuse of the
1409 smtp port for listening. */
1410
1411 if (setsockopt(listen_sockets[sk], SOL_SOCKET, SO_REUSEADDR,
1412 (uschar *)(&on), sizeof(on)) < 0)
1413 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "setting SO_REUSEADDR on socket "
1414 "failed when starting daemon: %s", strerror(errno));
1415
1416 /* Set TCP_NODELAY; Exim does its own buffering. There is a switch to
1417 disable this because it breaks some broken clients. */
1418
1419 if (tcp_nodelay) setsockopt(listen_sockets[sk], IPPROTO_TCP, TCP_NODELAY,
1420 (uschar *)(&on), sizeof(on));
1421
1422 /* Now bind the socket to the required port; if Exim is being restarted
1423 it may not always be possible to bind immediately, even with SO_REUSEADDR
1424 set, so try 10 times, waiting between each try. After 10 failures, we give
1425 up. In an IPv6 environment, if bind () fails with the error EADDRINUSE and
1426 we are doing wildcard IPv4 listening and there was a previous IPv6 wildcard
1427 address for the same port, ignore the error on the grounds that we must be
1428 in a system where the IPv6 socket accepts both kinds of call. This is
1429 necessary for (some release of) USAGI Linux; other IP stacks fail at the
1430 listen() stage instead. */
1431
1432 for(;;)
1433 {
1434 uschar *msg, *addr;
1435 if (ip_bind(listen_sockets[sk], af, ipa->address, ipa->port) >= 0) break;
1436 if (check_special_case(errno, addresses, ipa, TRUE))
1437 {
1438 DEBUG(D_any) debug_printf("wildcard IPv4 bind() failed after IPv6 "
1439 "listen() success; EADDRINUSE ignored\n");
1440 (void)close(listen_sockets[sk]);
1441 goto SKIP_SOCKET;
1442 }
1443 msg = US strerror(errno);
1444 addr = wildcard? ((af == AF_INET6)? US"(any IPv6)" : US"(any IPv4)") :
1445 ipa->address;
1446 if (daemon_startup_retries <= 0)
1447 log_write(0, LOG_MAIN|LOG_PANIC_DIE,
1448 "socket bind() to port %d for address %s failed: %s: "
1449 "daemon abandoned", ipa->port, addr, msg);
1450 log_write(0, LOG_MAIN, "socket bind() to port %d for address %s "
1451 "failed: %s: waiting %s before trying again (%d more %s)",
1452 ipa->port, addr, msg, readconf_printtime(daemon_startup_sleep),
1453 daemon_startup_retries, (daemon_startup_retries > 1)? "tries" : "try");
1454 daemon_startup_retries--;
1455 sleep(daemon_startup_sleep);
1456 }
1457
1458 DEBUG(D_any)
1459 {
1460 if (wildcard)
1461 debug_printf("listening on all interfaces (IPv%c) port %d\n",
1462 (af == AF_INET6)? '6' : '4', ipa->port);
1463 else
1464 debug_printf("listening on %s port %d\n", ipa->address, ipa->port);
1465 }
1466
1467 /* Start listening on the bound socket, establishing the maximum backlog of
1468 connections that is allowed. On success, continue to the next address. */
1469
1470 if (listen(listen_sockets[sk], smtp_connect_backlog) >= 0) continue;
1471
1472 /* Listening has failed. In an IPv6 environment, as for bind(), if listen()
1473 fails with the error EADDRINUSE and we are doing IPv4 wildcard listening
1474 and there was a previous successful IPv6 wildcard listen on the same port,
1475 we want to ignore the error on the grounds that we must be in a system
1476 where the IPv6 socket accepts both kinds of call. */
1477
1478 if (!check_special_case(errno, addresses, ipa, TRUE))
1479 log_write(0, LOG_PANIC_DIE, "listen() failed on interface %s: %s",
1480 wildcard? ((af == AF_INET6)? US"(any IPv6)" : US"(any IPv4)") :
1481 ipa->address,
1482 strerror(errno));
1483
1484 DEBUG(D_any) debug_printf("wildcard IPv4 listen() failed after IPv6 "
1485 "listen() success; EADDRINUSE ignored\n");
1486 (void)close(listen_sockets[sk]);
1487
1488 /* Come here if there has been a problem with the socket which we
1489 are going to ignore. We remove the address from the chain, and back up the
1490 counts. */
1491
1492 SKIP_SOCKET:
1493 sk--; /* Back up the count */
1494 listen_socket_count--; /* Reduce the total */
1495 if (ipa == addresses) addresses = ipa->next; else
1496 {
1497 for (ipa2 = addresses; ipa2->next != ipa; ipa2 = ipa2->next);
1498 ipa2->next = ipa->next;
1499 ipa = ipa2;
1500 }
1501 } /* End of bind/listen loop for each address */
1502 } /* End of setup for listening */
1503
1504
1505 /* If we are not listening, we want to write a pid file only if -oP was
1506 explicitly given. */
1507
1508 else if (override_pid_file_path == NULL) write_pid = FALSE;
1509
1510 /* Write the pid to a known file for assistance in identification, if required.
1511 We do this before giving up root privilege, because on some systems it is
1512 necessary to be root in order to write into the pid file directory. There's
1513 nothing to stop multiple daemons running, as long as no more than one listens
1514 on a given TCP/IP port on the same interface(s). However, in these
1515 circumstances it gets far too complicated to mess with pid file names
1516 automatically. Consequently, Exim 4 writes a pid file only
1517
1518 (a) When running in the test harness, or
1519 (b) When -bd is used and -oX is not used, or
1520 (c) When -oP is used to supply a path.
1521
1522 The variable daemon_write_pid is used to control this. */
1523
1524 if (running_in_test_harness || write_pid)
1525 {
1526 FILE *f;
1527
1528 if (override_pid_file_path != NULL)
1529 pid_file_path = override_pid_file_path;
1530
1531 if (pid_file_path[0] == 0)
1532 pid_file_path = string_sprintf("%s/exim-daemon.pid", spool_directory);
1533
1534 f = modefopen(pid_file_path, "wb", 0644);
1535 if (f != NULL)
1536 {
1537 (void)fprintf(f, "%d\n", (int)getpid());
1538 (void)fclose(f);
1539 DEBUG(D_any) debug_printf("pid written to %s\n", pid_file_path);
1540 }
1541 else
1542 {
1543 DEBUG(D_any)
1544 debug_printf("%s\n", string_open_failed(errno, "pid file %s",
1545 pid_file_path));
1546 }
1547 }
1548
1549 /* Set up the handler for SIGHUP, which causes a restart of the daemon. */
1550
1551 sighup_seen = FALSE;
1552 signal(SIGHUP, sighup_handler);
1553
1554 /* Give up root privilege at this point (assuming that exim_uid and exim_gid
1555 are not root). The third argument controls the running of initgroups().
1556 Normally we do this, in order to set up the groups for the Exim user. However,
1557 if we are not root at this time - some odd installations run that way - we
1558 cannot do this. */
1559
1560 exim_setugid(exim_uid, exim_gid, geteuid()==root_uid, US"running as a daemon");
1561
1562 /* Update the originator_xxx fields so that received messages as listed as
1563 coming from Exim, not whoever started the daemon. */
1564
1565 originator_uid = exim_uid;
1566 originator_gid = exim_gid;
1567 originator_login = ((pw = getpwuid(exim_uid)) != NULL)?
1568 string_copy_malloc(US pw->pw_name) : US"exim";
1569
1570 /* Get somewhere to keep the list of queue-runner pids if we are keeping track
1571 of them (and also if we are doing queue runs). */
1572
1573 if (queue_interval > 0 && queue_run_max > 0)
1574 {
1575 int i;
1576 queue_pid_slots = store_get(queue_run_max * sizeof(pid_t));
1577 for (i = 0; i < queue_run_max; i++) queue_pid_slots[i] = 0;
1578 }
1579
1580 /* Set up the handler for termination of child processes. */
1581
1582 sigchld_seen = FALSE;
1583 os_non_restarting_signal(SIGCHLD, main_sigchld_handler);
1584
1585 /* If we are to run the queue periodically, pretend the alarm has just gone
1586 off. This will cause the first queue-runner to get kicked off straight away. */
1587
1588 sigalrm_seen = (queue_interval > 0);
1589
1590 /* Log the start up of a daemon - at least one of listening or queue running
1591 must be set up. */
1592
1593 if (inetd_wait_mode)
1594 {
1595 uschar *p = big_buffer;
1596
1597 if (inetd_wait_timeout >= 0)
1598 sprintf(CS p, "terminating after %d seconds", inetd_wait_timeout);
1599 else
1600 sprintf(CS p, "with no wait timeout");
1601
1602 log_write(0, LOG_MAIN,
1603 "exim %s daemon started: pid=%d, launched with listening socket, %s",
1604 version_string, getpid(), big_buffer);
1605 set_process_info("daemon: pre-listening socket");
1606
1607 /* set up the timeout logic */
1608 sigalrm_seen = 1;
1609 }
1610
1611 else if (daemon_listen)
1612 {
1613 int i, j;
1614 int smtp_ports = 0;
1615 int smtps_ports = 0;
1616 ip_address_item *ipa;
1617 uschar *p = big_buffer;
1618 uschar *qinfo = (queue_interval > 0)?
1619 string_sprintf("-q%s", readconf_printtime(queue_interval))
1620 :
1621 US"no queue runs";
1622
1623 /* Build a list of listening addresses in big_buffer, but limit it to 10
1624 items. The style is for backwards compatibility.
1625
1626 It is now possible to have some ports listening for SMTPS (the old,
1627 deprecated protocol that starts TLS without using STARTTLS), and others
1628 listening for standard SMTP. Keep their listings separate. */
1629
1630 for (j = 0; j < 2; j++)
1631 {
1632 for (i = 0, ipa = addresses; i < 10 && ipa != NULL; i++, ipa = ipa->next)
1633 {
1634 /* First time round, look for SMTP ports; second time round, look for
1635 SMTPS ports. For the first one of each, insert leading text. */
1636
1637 if (host_is_tls_on_connect_port(ipa->port) == (j > 0))
1638 {
1639 if (j == 0)
1640 {
1641 if (smtp_ports++ == 0)
1642 {
1643 memcpy(p, "SMTP on", 8);
1644 p += 7;
1645 }
1646 }
1647 else
1648 {
1649 if (smtps_ports++ == 0)
1650 {
1651 (void)sprintf(CS p, "%sSMTPS on",
1652 (smtp_ports == 0)? "":" and for ");
1653 while (*p != 0) p++;
1654 }
1655 }
1656
1657 /* Now the information about the port (and sometimes interface) */
1658
1659 if (ipa->address[0] == ':' && ipa->address[1] == 0)
1660 {
1661 if (ipa->next != NULL && ipa->next->address[0] == 0 &&
1662 ipa->next->port == ipa->port)
1663 {
1664 (void)sprintf(CS p, " port %d (IPv6 and IPv4)", ipa->port);
1665 ipa = ipa->next;
1666 }
1667 else if (ipa->v6_include_v4)
1668 (void)sprintf(CS p, " port %d (IPv6 with IPv4)", ipa->port);
1669 else
1670 (void)sprintf(CS p, " port %d (IPv6)", ipa->port);
1671 }
1672 else if (ipa->address[0] == 0)
1673 (void)sprintf(CS p, " port %d (IPv4)", ipa->port);
1674 else
1675 (void)sprintf(CS p, " [%s]:%d", ipa->address, ipa->port);
1676 while (*p != 0) p++;
1677 }
1678 }
1679
1680 if (ipa != NULL)
1681 {
1682 memcpy(p, " ...", 5);
1683 p += 4;
1684 }
1685 }
1686
1687 log_write(0, LOG_MAIN,
1688 "exim %s daemon started: pid=%d, %s, listening for %s",
1689 version_string, getpid(), qinfo, big_buffer);
1690 set_process_info("daemon: %s, listening for %s", qinfo, big_buffer);
1691 }
1692
1693 else
1694 {
1695 log_write(0, LOG_MAIN,
1696 "exim %s daemon started: pid=%d, -q%s, not listening for SMTP",
1697 version_string, getpid(), readconf_printtime(queue_interval));
1698 set_process_info("daemon: -q%s, not listening",
1699 readconf_printtime(queue_interval));
1700 }
1701
1702 /* Do any work it might be useful to amortize over our children
1703 (eg: compile regex) */
1704
1705 deliver_init();
1706 dns_pattern_init();
1707
1708 #ifdef WITH_CONTENT_SCAN
1709 malware_init();
1710 #endif
1711
1712 /* Close the log so it can be renamed and moved. In the few cases below where
1713 this long-running process writes to the log (always exceptional conditions), it
1714 closes the log afterwards, for the same reason. */
1715
1716 log_close_all();
1717
1718 DEBUG(D_any) debug_print_ids(US"daemon running with");
1719
1720 /* Any messages accepted via this route are going to be SMTP. */
1721
1722 smtp_input = TRUE;
1723
1724 /* Enter the never-ending loop... */
1725
1726 for (;;)
1727 {
1728 #if HAVE_IPV6
1729 struct sockaddr_in6 accepted;
1730 #else
1731 struct sockaddr_in accepted;
1732 #endif
1733
1734 EXIM_SOCKLEN_T len;
1735 pid_t pid;
1736
1737 /* This code is placed first in the loop, so that it gets obeyed at the
1738 start, before the first wait, for the queue-runner case, so that the first
1739 one can be started immediately.
1740
1741 The other option is that we have an inetd wait timeout specified to -bw. */
1742
1743 if (sigalrm_seen)
1744 {
1745 if (inetd_wait_timeout > 0)
1746 {
1747 time_t resignal_interval = inetd_wait_timeout;
1748
1749 if (last_connection_time == (time_t)0)
1750 {
1751 DEBUG(D_any)
1752 debug_printf("inetd wait timeout expired, but still not seen first message, ignoring\n");
1753 }
1754 else
1755 {
1756 time_t now = time(NULL);
1757 if (now == (time_t)-1)
1758 {
1759 DEBUG(D_any) debug_printf("failed to get time: %s\n", strerror(errno));
1760 }
1761 else
1762 {
1763 if ((now - last_connection_time) >= inetd_wait_timeout)
1764 {
1765 DEBUG(D_any)
1766 debug_printf("inetd wait timeout %d expired, ending daemon\n",
1767 inetd_wait_timeout);
1768 log_write(0, LOG_MAIN, "exim %s daemon terminating, inetd wait timeout reached.\n",
1769 version_string);
1770 exit(EXIT_SUCCESS);
1771 }
1772 else
1773 {
1774 resignal_interval -= (now - last_connection_time);
1775 }
1776 }
1777 }
1778
1779 sigalrm_seen = FALSE;
1780 alarm(resignal_interval);
1781 }
1782
1783 else
1784 {
1785 DEBUG(D_any) debug_printf("SIGALRM received\n");
1786
1787 /* Do a full queue run in a child process, if required, unless we already
1788 have enough queue runners on the go. If we are not running as root, a
1789 re-exec is required. */
1790
1791 if (queue_interval > 0 &&
1792 (queue_run_max <= 0 || queue_run_count < queue_run_max))
1793 {
1794 if ((pid = fork()) == 0)
1795 {
1796 int sk;
1797
1798 DEBUG(D_any) debug_printf("Starting queue-runner: pid %d\n",
1799 (int)getpid());
1800
1801 /* Disable debugging if it's required only for the daemon process. We
1802 leave the above message, because it ties up with the "child ended"
1803 debugging messages. */
1804
1805 if (debug_daemon) debug_selector = 0;
1806
1807 /* Close any open listening sockets in the child */
1808
1809 for (sk = 0; sk < listen_socket_count; sk++)
1810 (void)close(listen_sockets[sk]);
1811
1812 /* Reset SIGHUP and SIGCHLD in the child in both cases. */
1813
1814 signal(SIGHUP, SIG_DFL);
1815 signal(SIGCHLD, SIG_DFL);
1816
1817 /* Re-exec if privilege has been given up, unless deliver_drop_
1818 privilege is set. Reset SIGALRM before exec(). */
1819
1820 if (geteuid() != root_uid && !deliver_drop_privilege)
1821 {
1822 uschar opt[8];
1823 uschar *p = opt;
1824 uschar *extra[5];
1825 int extracount = 1;
1826
1827 signal(SIGALRM, SIG_DFL);
1828 *p++ = '-';
1829 *p++ = 'q';
1830 if (queue_2stage) *p++ = 'q';
1831 if (queue_run_first_delivery) *p++ = 'i';
1832 if (queue_run_force) *p++ = 'f';
1833 if (deliver_force_thaw) *p++ = 'f';
1834 if (queue_run_local) *p++ = 'l';
1835 *p = 0;
1836 extra[0] = opt;
1837
1838 /* If -R or -S were on the original command line, ensure they get
1839 passed on. */
1840
1841 if (deliver_selectstring != NULL)
1842 {
1843 extra[extracount++] = deliver_selectstring_regex? US"-Rr" : US"-R";
1844 extra[extracount++] = deliver_selectstring;
1845 }
1846
1847 if (deliver_selectstring_sender != NULL)
1848 {
1849 extra[extracount++] = deliver_selectstring_sender_regex?
1850 US"-Sr" : US"-S";
1851 extra[extracount++] = deliver_selectstring_sender;
1852 }
1853
1854 /* Overlay this process with a new execution. */
1855
1856 (void)child_exec_exim(CEE_EXEC_PANIC, FALSE, NULL, TRUE, extracount,
1857 extra[0], extra[1], extra[2], extra[3], extra[4]);
1858
1859 /* Control never returns here. */
1860 }
1861
1862 /* No need to re-exec; SIGALRM remains set to the default handler */
1863
1864 queue_run(NULL, NULL, FALSE);
1865 _exit(EXIT_SUCCESS);
1866 }
1867
1868 if (pid < 0)
1869 {
1870 log_write(0, LOG_MAIN|LOG_PANIC, "daemon: fork of queue-runner "
1871 "process failed: %s", strerror(errno));
1872 log_close_all();
1873 }
1874 else
1875 {
1876 int i;
1877 for (i = 0; i < queue_run_max; ++i)
1878 {
1879 if (queue_pid_slots[i] <= 0)
1880 {
1881 queue_pid_slots[i] = pid;
1882 queue_run_count++;
1883 break;
1884 }
1885 }
1886 DEBUG(D_any) debug_printf("%d queue-runner process%s running\n",
1887 queue_run_count, (queue_run_count == 1)? "" : "es");
1888 }
1889 }
1890
1891 /* Reset the alarm clock */
1892
1893 sigalrm_seen = FALSE;
1894 alarm(queue_interval);
1895 }
1896
1897 } /* sigalrm_seen */
1898
1899
1900 /* Sleep till a connection happens if listening, and handle the connection if
1901 that is why we woke up. The FreeBSD operating system requires the use of
1902 select() before accept() because the latter function is not interrupted by
1903 a signal, and we want to wake up for SIGCHLD and SIGALRM signals. Some other
1904 OS do notice signals in accept() but it does no harm to have the select()
1905 in for all of them - and it won't then be a lurking problem for ports to
1906 new OS. In fact, the later addition of listening on specific interfaces only
1907 requires this way of working anyway. */
1908
1909 if (daemon_listen)
1910 {
1911 int sk, lcount, select_errno;
1912 int max_socket = 0;
1913 BOOL select_failed = FALSE;
1914 fd_set select_listen;
1915
1916 FD_ZERO(&select_listen);
1917 for (sk = 0; sk < listen_socket_count; sk++)
1918 {
1919 FD_SET(listen_sockets[sk], &select_listen);
1920 if (listen_sockets[sk] > max_socket) max_socket = listen_sockets[sk];
1921 }
1922
1923 DEBUG(D_any) debug_printf("Listening...\n");
1924
1925 /* In rare cases we may have had a SIGCHLD signal in the time between
1926 setting the handler (below) and getting back here. If so, pretend that the
1927 select() was interrupted so that we reap the child. This might still leave
1928 a small window when a SIGCHLD could get lost. However, since we use SIGCHLD
1929 only to do the reaping more quickly, it shouldn't result in anything other
1930 than a delay until something else causes a wake-up. */
1931
1932 if (sigchld_seen)
1933 {
1934 lcount = -1;
1935 errno = EINTR;
1936 }
1937 else
1938 {
1939 lcount = select(max_socket + 1, (SELECT_ARG2_TYPE *)&select_listen,
1940 NULL, NULL, NULL);
1941 }
1942
1943 if (lcount < 0)
1944 {
1945 select_failed = TRUE;
1946 lcount = 1;
1947 }
1948
1949 /* Clean up any subprocesses that may have terminated. We need to do this
1950 here so that smtp_accept_max_per_host works when a connection to that host
1951 has completed, and we are about to accept a new one. When this code was
1952 later in the sequence, a new connection could be rejected, even though an
1953 old one had just finished. Preserve the errno from any select() failure for
1954 the use of the common select/accept error processing below. */
1955
1956 select_errno = errno;
1957 handle_ending_processes();
1958 errno = select_errno;
1959
1960 /* Loop for all the sockets that are currently ready to go. If select
1961 actually failed, we have set the count to 1 and select_failed=TRUE, so as
1962 to use the common error code for select/accept below. */
1963
1964 while (lcount-- > 0)
1965 {
1966 int accept_socket = -1;
1967 if (!select_failed)
1968 {
1969 for (sk = 0; sk < listen_socket_count; sk++)
1970 {
1971 if (FD_ISSET(listen_sockets[sk], &select_listen))
1972 {
1973 len = sizeof(accepted);
1974 accept_socket = accept(listen_sockets[sk],
1975 (struct sockaddr *)&accepted, &len);
1976 FD_CLR(listen_sockets[sk], &select_listen);
1977 break;
1978 }
1979 }
1980 }
1981
1982 /* If select or accept has failed and this was not caused by an
1983 interruption, log the incident and try again. With asymmetric TCP/IP
1984 routing errors such as "No route to network" have been seen here. Also
1985 "connection reset by peer" has been seen. These cannot be classed as
1986 disastrous errors, but they could fill up a lot of log. The code in smail
1987 crashes the daemon after 10 successive failures of accept, on the grounds
1988 that some OS fail continuously. Exim originally followed suit, but this
1989 appears to have caused problems. Now it just keeps going, but instead of
1990 logging each error, it batches them up when they are continuous. */
1991
1992 if (accept_socket < 0 && errno != EINTR)
1993 {
1994 if (accept_retry_count == 0)
1995 {
1996 accept_retry_errno = errno;
1997 accept_retry_select_failed = select_failed;
1998 }
1999 else
2000 {
2001 if (errno != accept_retry_errno ||
2002 select_failed != accept_retry_select_failed ||
2003 accept_retry_count >= 50)
2004 {
2005 log_write(0, LOG_MAIN | ((accept_retry_count >= 50)? LOG_PANIC : 0),
2006 "%d %s() failure%s: %s",
2007 accept_retry_count,
2008 accept_retry_select_failed? "select" : "accept",
2009 (accept_retry_count == 1)? "" : "s",
2010 strerror(accept_retry_errno));
2011 log_close_all();
2012 accept_retry_count = 0;
2013 accept_retry_errno = errno;
2014 accept_retry_select_failed = select_failed;
2015 }
2016 }
2017 accept_retry_count++;
2018 }
2019
2020 else
2021 {
2022 if (accept_retry_count > 0)
2023 {
2024 log_write(0, LOG_MAIN, "%d %s() failure%s: %s",
2025 accept_retry_count,
2026 accept_retry_select_failed? "select" : "accept",
2027 (accept_retry_count == 1)? "" : "s",
2028 strerror(accept_retry_errno));
2029 log_close_all();
2030 accept_retry_count = 0;
2031 }
2032 }
2033
2034 /* If select/accept succeeded, deal with the connection. */
2035
2036 if (accept_socket >= 0)
2037 {
2038 if (inetd_wait_timeout)
2039 last_connection_time = time(NULL);
2040 handle_smtp_call(listen_sockets, listen_socket_count, accept_socket,
2041 (struct sockaddr *)&accepted);
2042 }
2043 }
2044 }
2045
2046 /* If not listening, then just sleep for the queue interval. If we woke
2047 up early the last time for some other signal, it won't matter because
2048 the alarm signal will wake at the right time. This code originally used
2049 sleep() but it turns out that on the FreeBSD system, sleep() is not inter-
2050 rupted by signals, so it wasn't waking up for SIGALRM or SIGCHLD. Luckily
2051 select() can be used as an interruptible sleep() on all versions of Unix. */
2052
2053 else
2054 {
2055 struct timeval tv;
2056 tv.tv_sec = queue_interval;
2057 tv.tv_usec = 0;
2058 select(0, NULL, NULL, NULL, &tv);
2059 handle_ending_processes();
2060 }
2061
2062 /* Re-enable the SIGCHLD handler if it has been run. It can't do it
2063 for itself, because it isn't doing the waiting itself. */
2064
2065 if (sigchld_seen)
2066 {
2067 sigchld_seen = FALSE;
2068 os_non_restarting_signal(SIGCHLD, main_sigchld_handler);
2069 }
2070
2071 /* Handle being woken by SIGHUP. We know at this point that the result
2072 of accept() has been dealt with, so we can re-exec exim safely, first
2073 closing the listening sockets so that they can be reused. Cancel any pending
2074 alarm in case it is just about to go off, and set SIGHUP to be ignored so
2075 that another HUP in quick succession doesn't clobber the new daemon before it
2076 gets going. All log files get closed by the close-on-exec flag; however, if
2077 the exec fails, we need to close the logs. */
2078
2079 if (sighup_seen)
2080 {
2081 int sk;
2082 log_write(0, LOG_MAIN, "pid %d: SIGHUP received: re-exec daemon",
2083 getpid());
2084 for (sk = 0; sk < listen_socket_count; sk++)
2085 (void)close(listen_sockets[sk]);
2086 alarm(0);
2087 signal(SIGHUP, SIG_IGN);
2088 sighup_argv[0] = exim_path;
2089 exim_nullstd();
2090 execv(CS exim_path, (char *const *)sighup_argv);
2091 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "pid %d: exec of %s failed: %s",
2092 getpid(), exim_path, strerror(errno));
2093 log_close_all();
2094 }
2095
2096 } /* End of main loop */
2097
2098 /* Control never reaches here */
2099 }
2100
2101 /* vi: aw ai sw=2
2102 */
2103 /* End of exim_daemon.c */