ACL: control = queue/first_pass_route
[exim.git] / src / src / daemon.c
1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
4
5 /* Copyright (c) University of Cambridge 1995 - 2018 */
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 assignments except as initializers in declarations). */
23
24 static smtp_slot empty_smtp_slot = { .pid = 0, .host_address = NULL };
25
26
27
28 /*************************************************
29 * Local static variables *
30 *************************************************/
31
32 static SIGNAL_BOOL sigchld_seen;
33 static SIGNAL_BOOL sighup_seen;
34 static SIGNAL_BOOL sigterm_seen;
35
36 static int accept_retry_count = 0;
37 static int accept_retry_errno;
38 static BOOL accept_retry_select_failed;
39
40 static int queue_run_count = 0;
41 static pid_t *queue_pid_slots = NULL;
42 static smtp_slot *smtp_slots = NULL;
43
44 static BOOL write_pid = TRUE;
45
46
47
48 /*************************************************
49 * SIGHUP Handler *
50 *************************************************/
51
52 /* All this handler does is to set a flag and re-enable the signal.
53
54 Argument: the signal number
55 Returns: nothing
56 */
57
58 static void
59 sighup_handler(int sig)
60 {
61 sig = sig; /* Keep picky compilers happy */
62 sighup_seen = TRUE;
63 signal(SIGHUP, sighup_handler);
64 }
65
66
67
68 /*************************************************
69 * SIGCHLD handler for main daemon process *
70 *************************************************/
71
72 /* Don't re-enable the handler here, since we aren't doing the
73 waiting here. If the signal is re-enabled, there will just be an
74 infinite sequence of calls to this handler. The SIGCHLD signal is
75 used just as a means of waking up the daemon so that it notices
76 terminated subprocesses as soon as possible.
77
78 Argument: the signal number
79 Returns: nothing
80 */
81
82 static void
83 main_sigchld_handler(int sig)
84 {
85 sig = sig; /* Keep picky compilers happy */
86 os_non_restarting_signal(SIGCHLD, SIG_DFL);
87 sigchld_seen = TRUE;
88 }
89
90
91 /* SIGTERM handler. Try to get the damon pif file removed
92 before exiting. */
93
94 static void
95 main_sigterm_handler(int sig)
96 {
97 sigterm_seen = TRUE;
98 }
99
100
101
102
103 /*************************************************
104 * Unexpected errors in SMTP calls *
105 *************************************************/
106
107 /* This function just saves a bit of repetitious coding.
108
109 Arguments:
110 log_msg Text of message to be logged
111 smtp_msg Text of SMTP error message
112 was_errno The failing errno
113
114 Returns: nothing
115 */
116
117 static void
118 never_error(uschar *log_msg, uschar *smtp_msg, int was_errno)
119 {
120 uschar *emsg = was_errno <= 0
121 ? US"" : string_sprintf(": %s", strerror(was_errno));
122 log_write(0, LOG_MAIN|LOG_PANIC, "%s%s", log_msg, emsg);
123 if (smtp_out) smtp_printf("421 %s\r\n", FALSE, smtp_msg);
124 }
125
126
127
128
129 /*************************************************
130 * Handle a connected SMTP call *
131 *************************************************/
132
133 /* This function is called when an SMTP connection has been accepted.
134 If there are too many, give an error message and close down. Otherwise
135 spin off a sub-process to handle the call. The list of listening sockets
136 is required so that they can be closed in the sub-process. Take care not to
137 leak store in this process - reset the stacking pool at the end.
138
139 Arguments:
140 listen_sockets sockets which are listening for incoming calls
141 listen_socket_count count of listening sockets
142 accept_socket socket of the current accepted call
143 accepted socket information about the current call
144
145 Returns: nothing
146 */
147
148 static void
149 handle_smtp_call(int *listen_sockets, int listen_socket_count,
150 int accept_socket, struct sockaddr *accepted)
151 {
152 pid_t pid;
153 union sockaddr_46 interface_sockaddr;
154 EXIM_SOCKLEN_T ifsize = sizeof(interface_sockaddr);
155 int dup_accept_socket = -1;
156 int max_for_this_host = 0;
157 int save_log_selector = *log_selector;
158 gstring * whofrom;
159
160 rmark reset_point = store_mark();
161
162 /* Make the address available in ASCII representation, and also fish out
163 the remote port. */
164
165 sender_host_address = host_ntoa(-1, accepted, NULL, &sender_host_port);
166 DEBUG(D_any) debug_printf("Connection request from %s port %d\n",
167 sender_host_address, sender_host_port);
168
169 /* Set up the output stream, check the socket has duplicated, and set up the
170 input stream. These operations fail only the exceptional circumstances. Note
171 that never_error() won't use smtp_out if it is NULL. */
172
173 if (!(smtp_out = fdopen(accept_socket, "wb")))
174 {
175 never_error(US"daemon: fdopen() for smtp_out failed", US"", errno);
176 goto ERROR_RETURN;
177 }
178
179 if ((dup_accept_socket = dup(accept_socket)) < 0)
180 {
181 never_error(US"daemon: couldn't dup socket descriptor",
182 US"Connection setup failed", errno);
183 goto ERROR_RETURN;
184 }
185
186 if (!(smtp_in = fdopen(dup_accept_socket, "rb")))
187 {
188 never_error(US"daemon: fdopen() for smtp_in failed",
189 US"Connection setup failed", errno);
190 goto ERROR_RETURN;
191 }
192
193 /* Get the data for the local interface address. Panic for most errors, but
194 "connection reset by peer" just means the connection went away. */
195
196 if (getsockname(accept_socket, (struct sockaddr *)(&interface_sockaddr),
197 &ifsize) < 0)
198 {
199 log_write(0, LOG_MAIN | ((errno == ECONNRESET)? 0 : LOG_PANIC),
200 "getsockname() failed: %s", strerror(errno));
201 smtp_printf("421 Local problem: getsockname() failed; please try again later\r\n", FALSE);
202 goto ERROR_RETURN;
203 }
204
205 interface_address = host_ntoa(-1, &interface_sockaddr, NULL, &interface_port);
206 DEBUG(D_interface) debug_printf("interface address=%s port=%d\n",
207 interface_address, interface_port);
208
209 /* Build a string identifying the remote host and, if requested, the port and
210 the local interface data. This is for logging; at the end of this function the
211 memory is reclaimed. */
212
213 whofrom = string_append(NULL, 3, "[", sender_host_address, "]");
214
215 if (LOGGING(incoming_port))
216 whofrom = string_fmt_append(whofrom, ":%d", sender_host_port);
217
218 if (LOGGING(incoming_interface))
219 whofrom = string_fmt_append(whofrom, " I=[%s]:%d",
220 interface_address, interface_port);
221
222 (void) string_from_gstring(whofrom); /* Terminate the newly-built string */
223
224 /* Check maximum number of connections. We do not check for reserved
225 connections or unacceptable hosts here. That is done in the subprocess because
226 it might take some time. */
227
228 if (smtp_accept_max > 0 && smtp_accept_count >= smtp_accept_max)
229 {
230 DEBUG(D_any) debug_printf("rejecting SMTP connection: count=%d max=%d\n",
231 smtp_accept_count, smtp_accept_max);
232 smtp_printf("421 Too many concurrent SMTP connections; "
233 "please try again later.\r\n", FALSE);
234 log_write(L_connection_reject,
235 LOG_MAIN, "Connection from %s refused: too many connections",
236 whofrom->s);
237 goto ERROR_RETURN;
238 }
239
240 /* If a load limit above which only reserved hosts are acceptable is defined,
241 get the load average here, and if there are in fact no reserved hosts, do
242 the test right away (saves a fork). If there are hosts, do the check in the
243 subprocess because it might take time. */
244
245 if (smtp_load_reserve >= 0)
246 {
247 load_average = OS_GETLOADAVG();
248 if (smtp_reserve_hosts == NULL && load_average > smtp_load_reserve)
249 {
250 DEBUG(D_any) debug_printf("rejecting SMTP connection: load average = %.2f\n",
251 (double)load_average/1000.0);
252 smtp_printf("421 Too much load; please try again later.\r\n", FALSE);
253 log_write(L_connection_reject,
254 LOG_MAIN, "Connection from %s refused: load average = %.2f",
255 whofrom->s, (double)load_average/1000.0);
256 goto ERROR_RETURN;
257 }
258 }
259
260 /* Check that one specific host (strictly, IP address) is not hogging
261 resources. This is done here to prevent a denial of service attack by someone
262 forcing you to fork lots of times before denying service. The value of
263 smtp_accept_max_per_host is a string which is expanded. This makes it possible
264 to provide host-specific limits according to $sender_host address, but because
265 this is in the daemon mainline, only fast expansions (such as inline address
266 checks) should be used. The documentation is full of warnings. */
267
268 if (smtp_accept_max_per_host != NULL)
269 {
270 uschar *expanded = expand_string(smtp_accept_max_per_host);
271 if (expanded == NULL)
272 {
273 if (!f.expand_string_forcedfail)
274 log_write(0, LOG_MAIN|LOG_PANIC, "expansion of smtp_accept_max_per_host "
275 "failed for %s: %s", whofrom->s, expand_string_message);
276 }
277 /* For speed, interpret a decimal number inline here */
278 else
279 {
280 uschar *s = expanded;
281 while (isdigit(*s))
282 max_for_this_host = max_for_this_host * 10 + *s++ - '0';
283 if (*s != 0)
284 log_write(0, LOG_MAIN|LOG_PANIC, "expansion of smtp_accept_max_per_host "
285 "for %s contains non-digit: %s", whofrom->s, expanded);
286 }
287 }
288
289 /* If we have fewer connections than max_for_this_host, we can skip the tedious
290 per host_address checks. Note that at this stage smtp_accept_count contains the
291 count of *other* connections, not including this one. */
292
293 if ((max_for_this_host > 0) &&
294 (smtp_accept_count >= max_for_this_host))
295 {
296 int host_accept_count = 0;
297 int other_host_count = 0; /* keep a count of non matches to optimise */
298
299 for (int i = 0; i < smtp_accept_max; ++i)
300 if (smtp_slots[i].host_address)
301 {
302 if (Ustrcmp(sender_host_address, smtp_slots[i].host_address) == 0)
303 host_accept_count++;
304 else
305 other_host_count++;
306
307 /* Testing all these strings is expensive - see if we can drop out
308 early, either by hitting the target, or finding there are not enough
309 connections left to make the target. */
310
311 if ((host_accept_count >= max_for_this_host) ||
312 ((smtp_accept_count - other_host_count) < max_for_this_host))
313 break;
314 }
315
316 if (host_accept_count >= max_for_this_host)
317 {
318 DEBUG(D_any) debug_printf("rejecting SMTP connection: too many from this "
319 "IP address: count=%d max=%d\n",
320 host_accept_count, max_for_this_host);
321 smtp_printf("421 Too many concurrent SMTP connections "
322 "from this IP address; please try again later.\r\n", FALSE);
323 log_write(L_connection_reject,
324 LOG_MAIN, "Connection from %s refused: too many connections "
325 "from that IP address", whofrom->s);
326 goto ERROR_RETURN;
327 }
328 }
329
330 /* OK, the connection count checks have been passed. Before we can fork the
331 accepting process, we must first log the connection if requested. This logging
332 used to happen in the subprocess, but doing that means that the value of
333 smtp_accept_count can be out of step by the time it is logged. So we have to do
334 the logging here and accept the performance cost. Note that smtp_accept_count
335 hasn't yet been incremented to take account of this connection.
336
337 In order to minimize the cost (because this is going to happen for every
338 connection), do a preliminary selector test here. This saves ploughing through
339 the generalized logging code each time when the selector is false. If the
340 selector is set, check whether the host is on the list for logging. If not,
341 arrange to unset the selector in the subprocess. */
342
343 if (LOGGING(smtp_connection))
344 {
345 uschar *list = hosts_connection_nolog;
346 memset(sender_host_cache, 0, sizeof(sender_host_cache));
347 if (list != NULL && verify_check_host(&list) == OK)
348 save_log_selector &= ~L_smtp_connection;
349 else
350 log_write(L_smtp_connection, LOG_MAIN, "SMTP connection from %s "
351 "(TCP/IP connection count = %d)", whofrom->s, smtp_accept_count + 1);
352 }
353
354 /* Now we can fork the accepting process; do a lookup tidy, just in case any
355 expansion above did a lookup. */
356
357 search_tidyup();
358 pid = fork();
359
360 /* Handle the child process */
361
362 if (pid == 0)
363 {
364 int i;
365 int queue_only_reason = 0;
366 int old_pool = store_pool;
367 int save_debug_selector = debug_selector;
368 BOOL local_queue_only;
369 BOOL session_local_queue_only;
370 #ifdef SA_NOCLDWAIT
371 struct sigaction act;
372 #endif
373
374 smtp_accept_count++; /* So that it includes this process */
375
376 /* May have been modified for the subprocess */
377
378 *log_selector = save_log_selector;
379
380 /* Get the local interface address into permanent store */
381
382 store_pool = POOL_PERM;
383 interface_address = string_copy(interface_address);
384 store_pool = old_pool;
385
386 /* Check for a tls-on-connect port */
387
388 if (host_is_tls_on_connect_port(interface_port)) tls_in.on_connect = TRUE;
389
390 /* Expand smtp_active_hostname if required. We do not do this any earlier,
391 because it may depend on the local interface address (indeed, that is most
392 likely what it depends on.) */
393
394 smtp_active_hostname = primary_hostname;
395 if (raw_active_hostname)
396 {
397 uschar * nah = expand_string(raw_active_hostname);
398 if (!nah)
399 {
400 if (!f.expand_string_forcedfail)
401 {
402 log_write(0, LOG_MAIN|LOG_PANIC, "failed to expand \"%s\" "
403 "(smtp_active_hostname): %s", raw_active_hostname,
404 expand_string_message);
405 smtp_printf("421 Local configuration error; "
406 "please try again later.\r\n", FALSE);
407 mac_smtp_fflush();
408 search_tidyup();
409 exim_underbar_exit(EXIT_FAILURE);
410 }
411 }
412 else if (*nah) smtp_active_hostname = nah;
413 }
414
415 /* Initialize the queueing flags */
416
417 queue_check_only();
418 session_local_queue_only = queue_only;
419
420 /* Close the listening sockets, and set the SIGCHLD handler to SIG_IGN.
421 We also attempt to set things up so that children are automatically reaped,
422 but just in case this isn't available, there's a paranoid waitpid() in the
423 loop too (except for systems where we are sure it isn't needed). See the more
424 extensive comment before the reception loop in exim.c for a fuller
425 explanation of this logic. */
426
427 for (i = 0; i < listen_socket_count; i++) (void)close(listen_sockets[i]);
428
429 /* Set FD_CLOEXEC on the SMTP socket. We don't want any rogue child processes
430 to be able to communicate with them, under any circumstances. */
431 (void)fcntl(accept_socket, F_SETFD,
432 fcntl(accept_socket, F_GETFD) | FD_CLOEXEC);
433 (void)fcntl(dup_accept_socket, F_SETFD,
434 fcntl(dup_accept_socket, F_GETFD) | FD_CLOEXEC);
435
436 #ifdef SA_NOCLDWAIT
437 act.sa_handler = SIG_IGN;
438 sigemptyset(&(act.sa_mask));
439 act.sa_flags = SA_NOCLDWAIT;
440 sigaction(SIGCHLD, &act, NULL);
441 #else
442 signal(SIGCHLD, SIG_IGN);
443 #endif
444 signal(SIGTERM, SIG_DFL);
445
446 /* Attempt to get an id from the sending machine via the RFC 1413
447 protocol. We do this in the sub-process in order not to hold up the
448 main process if there is any delay. Then set up the fullhost information
449 in case there is no HELO/EHLO.
450
451 If debugging is enabled only for the daemon, we must turn if off while
452 finding the id, but turn it on again afterwards so that information about the
453 incoming connection is output. */
454
455 if (f.debug_daemon) debug_selector = 0;
456 verify_get_ident(IDENT_PORT);
457 host_build_sender_fullhost();
458 debug_selector = save_debug_selector;
459
460 DEBUG(D_any)
461 debug_printf("Process %d is handling incoming connection from %s\n",
462 (int)getpid(), sender_fullhost);
463
464 /* Now disable debugging permanently if it's required only for the daemon
465 process. */
466
467 if (f.debug_daemon) debug_selector = 0;
468
469 /* If there are too many child processes for immediate delivery,
470 set the session_local_queue_only flag, which is initialized from the
471 configured value and may therefore already be TRUE. Leave logging
472 till later so it will have a message id attached. Note that there is no
473 possibility of re-calculating this per-message, because the value of
474 smtp_accept_count does not change in this subprocess. */
475
476 if (smtp_accept_queue > 0 && smtp_accept_count > smtp_accept_queue)
477 {
478 session_local_queue_only = TRUE;
479 queue_only_reason = 1;
480 }
481
482 /* Handle the start of the SMTP session, then loop, accepting incoming
483 messages from the SMTP connection. The end will come at the QUIT command,
484 when smtp_setup_msg() returns 0. A break in the connection causes the
485 process to die (see accept.c).
486
487 NOTE: We do *not* call smtp_log_no_mail() if smtp_start_session() fails,
488 because a log line has already been written for all its failure exists
489 (usually "connection refused: <reason>") and writing another one is
490 unnecessary clutter. */
491
492 if (!smtp_start_session())
493 {
494 mac_smtp_fflush();
495 search_tidyup();
496 exim_underbar_exit(EXIT_SUCCESS);
497 }
498
499 for (;;)
500 {
501 int rc;
502 message_id[0] = 0; /* Clear out any previous message_id */
503 reset_point = store_mark(); /* Save current store high water point */
504
505 DEBUG(D_any)
506 debug_printf("Process %d is ready for new message\n", (int)getpid());
507
508 /* Smtp_setup_msg() returns 0 on QUIT or if the call is from an
509 unacceptable host or if an ACL "drop" command was triggered, -1 on
510 connection lost, and +1 on validly reaching DATA. Receive_msg() almost
511 always returns TRUE when smtp_input is true; just retry if no message was
512 accepted (can happen for invalid message parameters). However, it can yield
513 FALSE if the connection was forcibly dropped by the DATA ACL. */
514
515 if ((rc = smtp_setup_msg()) > 0)
516 {
517 BOOL ok = receive_msg(FALSE);
518 search_tidyup(); /* Close cached databases */
519 if (!ok) /* Connection was dropped */
520 {
521 cancel_cutthrough_connection(TRUE, US"receive dropped");
522 mac_smtp_fflush();
523 smtp_log_no_mail(); /* Log no mail if configured */
524 exim_underbar_exit(EXIT_SUCCESS);
525 }
526 if (message_id[0] == 0) continue; /* No message was accepted */
527 }
528 else
529 {
530 if (smtp_out)
531 {
532 int fd = fileno(smtp_in);
533 uschar buf[128];
534
535 mac_smtp_fflush();
536 /* drain socket, for clean TCP FINs */
537 if (fcntl(fd, F_SETFL, O_NONBLOCK) == 0)
538 for(int i = 16; read(fd, buf, sizeof(buf)) > 0 && i > 0; ) i--;
539 }
540 cancel_cutthrough_connection(TRUE, US"message setup dropped");
541 search_tidyup();
542 smtp_log_no_mail(); /* Log no mail if configured */
543
544 /*XXX should we pause briefly, hoping that the client will be the
545 active TCP closer hence get the TCP_WAIT endpoint? */
546 DEBUG(D_receive) debug_printf("SMTP>>(close on process exit)\n");
547 exim_underbar_exit(rc ? EXIT_FAILURE : EXIT_SUCCESS);
548 }
549
550 /* Show the recipients when debugging */
551
552 DEBUG(D_receive)
553 {
554 if (sender_address)
555 debug_printf("Sender: %s\n", sender_address);
556 if (recipients_list)
557 {
558 debug_printf("Recipients:\n");
559 for (int i = 0; i < recipients_count; i++)
560 debug_printf(" %s\n", recipients_list[i].address);
561 }
562 }
563
564 /* A message has been accepted. Clean up any previous delivery processes
565 that have completed and are defunct, on systems where they don't go away
566 by themselves (see comments when setting SIG_IGN above). On such systems
567 (if any) these delivery processes hang around after termination until
568 the next message is received. */
569
570 #ifndef SIG_IGN_WORKS
571 while (waitpid(-1, NULL, WNOHANG) > 0);
572 #endif
573
574 /* Reclaim up the store used in accepting this message */
575
576 {
577 int r = receive_messagecount;
578 BOOL q = f.queue_only_policy;
579 smtp_reset(reset_point);
580 reset_point = NULL;
581 f.queue_only_policy = q;
582 receive_messagecount = r;
583 }
584
585 /* If queue_only is set or if there are too many incoming connections in
586 existence, session_local_queue_only will be TRUE. If it is not, check
587 whether we have received too many messages in this session for immediate
588 delivery. */
589
590 if (!session_local_queue_only &&
591 smtp_accept_queue_per_connection > 0 &&
592 receive_messagecount > smtp_accept_queue_per_connection)
593 {
594 session_local_queue_only = TRUE;
595 queue_only_reason = 2;
596 }
597
598 /* Initialize local_queue_only from session_local_queue_only. If it is not
599 true, and queue_only_load is set, check that the load average is below it.
600 If local_queue_only is set by this means, we also set if for the session if
601 queue_only_load_latch is true (the default). This means that, once set,
602 local_queue_only remains set for any subsequent messages on the same SMTP
603 connection. This is a deliberate choice; even though the load average may
604 fall, it doesn't seem right to deliver later messages on the same call when
605 not delivering earlier ones. However, the are special circumstances such as
606 very long-lived connections from scanning appliances where this is not the
607 best strategy. In such cases, queue_only_load_latch should be set false. */
608
609 if ( !(local_queue_only = session_local_queue_only)
610 && queue_only_load >= 0
611 && (local_queue_only = (load_average = OS_GETLOADAVG()) > queue_only_load)
612 )
613 {
614 queue_only_reason = 3;
615 if (queue_only_load_latch) session_local_queue_only = TRUE;
616 }
617
618 /* Log the queueing here, when it will get a message id attached, but
619 not if queue_only is set (case 0). */
620
621 if (local_queue_only) switch(queue_only_reason)
622 {
623 case 1: log_write(L_delay_delivery,
624 LOG_MAIN, "no immediate delivery: too many connections "
625 "(%d, max %d)", smtp_accept_count, smtp_accept_queue);
626 break;
627
628 case 2: log_write(L_delay_delivery,
629 LOG_MAIN, "no immediate delivery: more than %d messages "
630 "received in one connection", smtp_accept_queue_per_connection);
631 break;
632
633 case 3: log_write(L_delay_delivery,
634 LOG_MAIN, "no immediate delivery: load average %.2f",
635 (double)load_average/1000.0);
636 break;
637 }
638
639 /* If a delivery attempt is required, spin off a new process to handle it.
640 If we are not root, we have to re-exec exim unless deliveries are being
641 done unprivileged. */
642
643 else if ( (!f.queue_only_policy || f.queue_smtp)
644 && !f.deliver_freeze)
645 {
646 pid_t dpid;
647
648 /* Before forking, ensure that the C output buffer is flushed. Otherwise
649 anything that it in it will get duplicated, leading to duplicate copies
650 of the pending output. */
651
652 mac_smtp_fflush();
653
654 if ((dpid = fork()) == 0)
655 {
656 (void)fclose(smtp_in);
657 (void)fclose(smtp_out);
658
659 /* Don't ever molest the parent's SSL connection, but do clean up
660 the data structures if necessary. */
661
662 #ifndef DISABLE_TLS
663 tls_close(NULL, TLS_NO_SHUTDOWN);
664 #endif
665
666 /* Reset SIGHUP and SIGCHLD in the child in both cases. */
667
668 signal(SIGHUP, SIG_DFL);
669 signal(SIGCHLD, SIG_DFL);
670 signal(SIGTERM, SIG_DFL);
671
672 if (geteuid() != root_uid && !deliver_drop_privilege)
673 {
674 signal(SIGALRM, SIG_DFL);
675 delivery_re_exec(CEE_EXEC_PANIC);
676 /* Control does not return here. */
677 }
678
679 /* No need to re-exec; SIGALRM remains set to the default handler */
680
681 (void) deliver_message(message_id, FALSE, FALSE);
682 search_tidyup();
683 exim_underbar_exit(EXIT_SUCCESS);
684 }
685
686 if (dpid > 0)
687 {
688 release_cutthrough_connection(US"passed for delivery");
689 DEBUG(D_any) debug_printf("forked delivery process %d\n", (int)dpid);
690 }
691 else
692 {
693 cancel_cutthrough_connection(TRUE, US"delivery fork failed");
694 log_write(0, LOG_MAIN|LOG_PANIC, "daemon: delivery process fork "
695 "failed: %s", strerror(errno));
696 }
697 }
698 }
699 }
700
701
702 /* Carrying on in the parent daemon process... Can't do much if the fork
703 failed. Otherwise, keep count of the number of accepting processes and
704 remember the pid for ticking off when the child completes. */
705
706 if (pid < 0)
707 never_error(US"daemon: accept process fork failed", US"Fork failed", errno);
708 else
709 {
710 for (int i = 0; i < smtp_accept_max; ++i)
711 if (smtp_slots[i].pid <= 0)
712 {
713 smtp_slots[i].pid = pid;
714 /* Connection closes come asyncronously, so we cannot stack this store */
715 if (smtp_accept_max_per_host)
716 smtp_slots[i].host_address = string_copy_malloc(sender_host_address);
717 smtp_accept_count++;
718 break;
719 }
720 DEBUG(D_any) debug_printf("%d SMTP accept process%s running\n",
721 smtp_accept_count, smtp_accept_count == 1 ? "" : "es");
722 }
723
724 /* Get here via goto in error cases */
725
726 ERROR_RETURN:
727
728 /* Close the streams associated with the socket which will also close the
729 socket fds in this process. We can't do anything if fclose() fails, but
730 logging brings it to someone's attention. However, "connection reset by peer"
731 isn't really a problem, so skip that one. On Solaris, a dropped connection can
732 manifest itself as a broken pipe, so drop that one too. If the streams don't
733 exist, something went wrong while setting things up. Make sure the socket
734 descriptors are closed, in order to drop the connection. */
735
736 if (smtp_out)
737 {
738 if (fclose(smtp_out) != 0 && errno != ECONNRESET && errno != EPIPE)
739 log_write(0, LOG_MAIN|LOG_PANIC, "daemon: fclose(smtp_out) failed: %s",
740 strerror(errno));
741 smtp_out = NULL;
742 }
743 else (void)close(accept_socket);
744
745 if (smtp_in)
746 {
747 if (fclose(smtp_in) != 0 && errno != ECONNRESET && errno != EPIPE)
748 log_write(0, LOG_MAIN|LOG_PANIC, "daemon: fclose(smtp_in) failed: %s",
749 strerror(errno));
750 smtp_in = NULL;
751 }
752 else (void)close(dup_accept_socket);
753
754 /* Release any store used in this process, including the store used for holding
755 the incoming host address and an expanded active_hostname. */
756
757 log_close_all();
758 interface_address =
759 sender_host_address = NULL;
760 store_reset(reset_point);
761 sender_host_address = NULL;
762 }
763
764
765
766
767 /*************************************************
768 * Check wildcard listen special cases *
769 *************************************************/
770
771 /* This function is used when binding and listening on lists of addresses and
772 ports. It tests for special cases of wildcard listening, when IPv4 and IPv6
773 sockets may interact in different ways in different operating systems. It is
774 passed an error number, the list of listening addresses, and the current
775 address. Two checks are available: for a previous wildcard IPv6 address, or for
776 a following wildcard IPv4 address, in both cases on the same port.
777
778 In practice, pairs of wildcard addresses should be adjacent in the address list
779 because they are sorted that way below.
780
781 Arguments:
782 eno the error number
783 addresses the list of addresses
784 ipa the current IP address
785 back if TRUE, check for previous wildcard IPv6 address
786 if FALSE, check for a following wildcard IPv4 address
787
788 Returns: TRUE or FALSE
789 */
790
791 static BOOL
792 check_special_case(int eno, ip_address_item *addresses, ip_address_item *ipa,
793 BOOL back)
794 {
795 ip_address_item *ipa2;
796
797 /* For the "back" case, if the failure was "address in use" for a wildcard IPv4
798 address, seek a previous IPv6 wildcard address on the same port. As it is
799 previous, it must have been successfully bound and be listening. Flag it as a
800 "6 including 4" listener. */
801
802 if (back)
803 {
804 if (eno != EADDRINUSE || ipa->address[0] != 0) return FALSE;
805 for (ipa2 = addresses; ipa2 != ipa; ipa2 = ipa2->next)
806 {
807 if (ipa2->address[1] == 0 && ipa2->port == ipa->port)
808 {
809 ipa2->v6_include_v4 = TRUE;
810 return TRUE;
811 }
812 }
813 }
814
815 /* For the "forward" case, if the current address is a wildcard IPv6 address,
816 we seek a following wildcard IPv4 address on the same port. */
817
818 else
819 {
820 if (ipa->address[0] != ':' || ipa->address[1] != 0) return FALSE;
821 for (ipa2 = ipa->next; ipa2 != NULL; ipa2 = ipa2->next)
822 if (ipa2->address[0] == 0 && ipa->port == ipa2->port) return TRUE;
823 }
824
825 return FALSE;
826 }
827
828
829
830
831 /*************************************************
832 * Handle terminating subprocesses *
833 *************************************************/
834
835 /* Handle the termination of child processes. Theoretically, this need be done
836 only when sigchld_seen is TRUE, but rumour has it that some systems lose
837 SIGCHLD signals at busy times, so to be on the safe side, this function is
838 called each time round. It shouldn't be too expensive.
839
840 Arguments: none
841 Returns: nothing
842 */
843
844 static void
845 handle_ending_processes(void)
846 {
847 int status;
848 pid_t pid;
849
850 while ((pid = waitpid(-1, &status, WNOHANG)) > 0)
851 {
852 DEBUG(D_any)
853 {
854 debug_printf("child %d ended: status=0x%x\n", (int)pid, status);
855 #ifdef WCOREDUMP
856 if (WIFEXITED(status))
857 debug_printf(" normal exit, %d\n", WEXITSTATUS(status));
858 else if (WIFSIGNALED(status))
859 debug_printf(" signal exit, signal %d%s\n", WTERMSIG(status),
860 WCOREDUMP(status) ? " (core dumped)" : "");
861 #endif
862 }
863
864 /* If it's a listening daemon for which we are keeping track of individual
865 subprocesses, deal with an accepting process that has terminated. */
866
867 if (smtp_slots)
868 {
869 int i;
870 for (i = 0; i < smtp_accept_max; i++)
871 if (smtp_slots[i].pid == pid)
872 {
873 if (smtp_slots[i].host_address)
874 store_free(smtp_slots[i].host_address);
875 smtp_slots[i] = empty_smtp_slot;
876 if (--smtp_accept_count < 0) smtp_accept_count = 0;
877 DEBUG(D_any) debug_printf("%d SMTP accept process%s now running\n",
878 smtp_accept_count, (smtp_accept_count == 1)? "" : "es");
879 break;
880 }
881 if (i < smtp_accept_max) continue; /* Found an accepting process */
882 }
883
884 /* If it wasn't an accepting process, see if it was a queue-runner
885 process that we are tracking. */
886
887 if (queue_pid_slots)
888 {
889 int max = atoi(CS expand_string(queue_run_max));
890 for (int i = 0; i < max; i++)
891 if (queue_pid_slots[i] == pid)
892 {
893 queue_pid_slots[i] = 0;
894 if (--queue_run_count < 0) queue_run_count = 0;
895 DEBUG(D_any) debug_printf("%d queue-runner process%s now running\n",
896 queue_run_count, (queue_run_count == 1)? "" : "es");
897 break;
898 }
899 }
900 }
901 }
902
903
904
905 static void
906 set_pid_file_path(void)
907 {
908 if (override_pid_file_path)
909 pid_file_path = override_pid_file_path;
910
911 if (!*pid_file_path)
912 pid_file_path = string_sprintf("%s/exim-daemon.pid", spool_directory);
913 }
914
915
916 /* Remove the daemon's pidfile. Note: runs with root privilege,
917 as a direct child of the daemon. Does not return. */
918
919 void
920 delete_pid_file(void)
921 {
922 uschar * daemon_pid = string_sprintf("%d\n", (int)getppid());
923 FILE * f;
924
925 set_pid_file_path();
926 if ((f = Ufopen(pid_file_path, "rb")))
927 {
928 if ( fgets(CS big_buffer, big_buffer_size, f)
929 && Ustrcmp(daemon_pid, big_buffer) == 0
930 )
931 if (Uunlink(pid_file_path) == 0)
932 {
933 DEBUG(D_any)
934 debug_printf("%s unlink: %s\n", pid_file_path, strerror(errno));
935 }
936 else
937 DEBUG(D_any)
938 debug_printf("unlinked %s\n", pid_file_path);
939 fclose(f);
940 }
941 else
942 DEBUG(D_any)
943 debug_printf("%s\n", string_open_failed(errno, "pid file %s",
944 pid_file_path));
945 exim_exit(EXIT_SUCCESS, US"pid file remover");
946 }
947
948
949 /* Called by the daemon; exec a child to get the pid file deleted
950 since we may require privs for the containing directory */
951
952 static void
953 daemon_die(void)
954 {
955 int pid;
956
957 if (f.running_in_test_harness || write_pid)
958 {
959 if ((pid = fork()) == 0)
960 {
961 if (override_pid_file_path)
962 (void)child_exec_exim(CEE_EXEC_PANIC, FALSE, NULL, FALSE, 3,
963 "-oP", override_pid_file_path, "-oPX");
964 else
965 (void)child_exec_exim(CEE_EXEC_PANIC, FALSE, NULL, FALSE, 1, "-oPX");
966
967 /* Control never returns here. */
968 }
969 if (pid > 0)
970 child_close(pid, 1);
971 }
972 exim_exit(EXIT_SUCCESS, US"daemon");
973 }
974
975
976 /*************************************************
977 * Exim Daemon Mainline *
978 *************************************************/
979
980 /* The daemon can do two jobs, either of which is optional:
981
982 (1) Listens for incoming SMTP calls and spawns off a sub-process to handle
983 each one. This is requested by the -bd option, with -oX specifying the SMTP
984 port on which to listen (for testing).
985
986 (2) Spawns a queue-running process every so often. This is controlled by the
987 -q option with a an interval time. (If no time is given, a single queue run
988 is done from the main function, and control doesn't get here.)
989
990 Root privilege is required in order to attach to port 25. Some systems require
991 it when calling socket() rather than bind(). To cope with all cases, we run as
992 root for both socket() and bind(). Some systems also require root in order to
993 write to the pid file directory. This function must therefore be called as root
994 if it is to work properly in all circumstances. Once the socket is bound and
995 the pid file written, root privilege is given up if there is an exim uid.
996
997 There are no arguments to this function, and it never returns. */
998
999 void
1000 daemon_go(void)
1001 {
1002 struct passwd *pw;
1003 int *listen_sockets = NULL;
1004 int listen_socket_count = 0;
1005 ip_address_item *addresses = NULL;
1006 time_t last_connection_time = (time_t)0;
1007 int local_queue_run_max = atoi(CS expand_string(queue_run_max));
1008
1009 /* If any debugging options are set, turn on the D_pid bit so that all
1010 debugging lines get the pid added. */
1011
1012 DEBUG(D_any|D_v) debug_selector |= D_pid;
1013
1014 if (f.inetd_wait_mode)
1015 {
1016 listen_socket_count = 1;
1017 listen_sockets = store_get(sizeof(int), FALSE);
1018 (void) close(3);
1019 if (dup2(0, 3) == -1)
1020 log_write(0, LOG_MAIN|LOG_PANIC_DIE,
1021 "failed to dup inetd socket safely away: %s", strerror(errno));
1022
1023 listen_sockets[0] = 3;
1024 (void) close(0);
1025 (void) close(1);
1026 (void) close(2);
1027 exim_nullstd();
1028
1029 if (debug_file == stderr)
1030 {
1031 /* need a call to log_write before call to open debug_file, so that
1032 log.c:file_path has been initialised. This is unfortunate. */
1033 log_write(0, LOG_MAIN, "debugging Exim in inetd wait mode starting");
1034
1035 fclose(debug_file);
1036 debug_file = NULL;
1037 exim_nullstd(); /* re-open fd2 after we just closed it again */
1038 debug_logging_activate(US"-wait", NULL);
1039 }
1040
1041 DEBUG(D_any) debug_printf("running in inetd wait mode\n");
1042
1043 /* As per below, when creating sockets ourselves, we handle tcp_nodelay for
1044 our own buffering; we assume though that inetd set the socket REUSEADDR. */
1045
1046 if (tcp_nodelay)
1047 if (setsockopt(3, IPPROTO_TCP, TCP_NODELAY, US &on, sizeof(on)))
1048 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "failed to set socket NODELAY: %s",
1049 strerror(errno));
1050 }
1051
1052
1053 if (f.inetd_wait_mode || f.daemon_listen)
1054 {
1055 /* If any option requiring a load average to be available during the
1056 reception of a message is set, call os_getloadavg() while we are root
1057 for those OS for which this is necessary the first time it is called (in
1058 order to perform an "open" on the kernel memory file). */
1059
1060 #ifdef LOAD_AVG_NEEDS_ROOT
1061 if (queue_only_load >= 0 || smtp_load_reserve >= 0 ||
1062 (deliver_queue_load_max >= 0 && deliver_drop_privilege))
1063 (void)os_getloadavg();
1064 #endif
1065 }
1066
1067
1068 /* Do the preparation for setting up a listener on one or more interfaces, and
1069 possible on various ports. This is controlled by the combination of
1070 local_interfaces (which can set IP addresses and ports) and daemon_smtp_port
1071 (which is a list of default ports to use for those items in local_interfaces
1072 that do not specify a port). The -oX command line option can be used to
1073 override one or both of these options.
1074
1075 If local_interfaces is not set, the default is to listen on all interfaces.
1076 When it is set, it can include "all IPvx interfaces" as an item. This is useful
1077 when different ports are in use.
1078
1079 It turns out that listening on all interfaces is messy in an IPv6 world,
1080 because several different implementation approaches have been taken. This code
1081 is now supposed to work with all of them. The point of difference is whether an
1082 IPv6 socket that is listening on all interfaces will receive incoming IPv4
1083 calls or not. We also have to cope with the case when IPv6 libraries exist, but
1084 there is no IPv6 support in the kernel.
1085
1086 . On Solaris, an IPv6 socket will accept IPv4 calls, and give them as mapped
1087 addresses. However, if an IPv4 socket is also listening on all interfaces,
1088 calls are directed to the appropriate socket.
1089
1090 . On (some versions of) Linux, an IPv6 socket will accept IPv4 calls, and
1091 give them as mapped addresses, but an attempt also to listen on an IPv4
1092 socket on all interfaces causes an error.
1093
1094 . On OpenBSD, an IPv6 socket will not accept IPv4 calls. You have to set up
1095 two sockets if you want to accept both kinds of call.
1096
1097 . FreeBSD is like OpenBSD, but it has the IPV6_V6ONLY socket option, which
1098 can be turned off, to make it behave like the versions of Linux described
1099 above.
1100
1101 . I heard a report that the USAGI IPv6 stack for Linux has implemented
1102 IPV6_V6ONLY.
1103
1104 So, what we do when IPv6 is supported is as follows:
1105
1106 (1) After it is set up, the list of interfaces is scanned for wildcard
1107 addresses. If an IPv6 and an IPv4 wildcard are both found for the same
1108 port, the list is re-arranged so that they are together, with the IPv6
1109 wildcard first.
1110
1111 (2) If the creation of a wildcard IPv6 socket fails, we just log the error and
1112 carry on if an IPv4 wildcard socket for the same port follows later in the
1113 list. This allows Exim to carry on in the case when the kernel has no IPv6
1114 support.
1115
1116 (3) Having created an IPv6 wildcard socket, we try to set IPV6_V6ONLY if that
1117 option is defined. However, if setting fails, carry on regardless (but log
1118 the incident).
1119
1120 (4) If binding or listening on an IPv6 wildcard socket fails, it is a serious
1121 error.
1122
1123 (5) If binding or listening on an IPv4 wildcard socket fails with the error
1124 EADDRINUSE, and a previous interface was an IPv6 wildcard for the same
1125 port (which must have succeeded or we wouldn't have got this far), we
1126 assume we are in the situation where just a single socket is permitted,
1127 and ignore the error.
1128
1129 Phew!
1130
1131 The preparation code decodes options and sets up the relevant data. We do this
1132 first, so that we can return non-zero if there are any syntax errors, and also
1133 write to stderr. */
1134
1135 if (f.daemon_listen && !f.inetd_wait_mode)
1136 {
1137 int *default_smtp_port;
1138 int sep;
1139 int pct = 0;
1140 uschar *s;
1141 const uschar * list;
1142 uschar *local_iface_source = US"local_interfaces";
1143 ip_address_item *ipa;
1144 ip_address_item **pipa;
1145
1146 /* If -oX was used, disable the writing of a pid file unless -oP was
1147 explicitly used to force it. Then scan the string given to -oX. Any items
1148 that contain neither a dot nor a colon are used to override daemon_smtp_port.
1149 Any other items are used to override local_interfaces. */
1150
1151 if (override_local_interfaces)
1152 {
1153 gstring * new_smtp_port = NULL;
1154 gstring * new_local_interfaces = NULL;
1155
1156 if (!override_pid_file_path) write_pid = FALSE;
1157
1158 list = override_local_interfaces;
1159 sep = 0;
1160 while ((s = string_nextinlist(&list, &sep, big_buffer, big_buffer_size)))
1161 {
1162 uschar joinstr[4];
1163 gstring ** gp = Ustrpbrk(s, ".:") ? &new_local_interfaces : &new_smtp_port;
1164
1165 if (!*gp)
1166 {
1167 joinstr[0] = sep;
1168 joinstr[1] = ' ';
1169 *gp = string_catn(*gp, US"<", 1);
1170 }
1171
1172 *gp = string_catn(*gp, joinstr, 2);
1173 *gp = string_cat (*gp, s);
1174 }
1175
1176 if (new_smtp_port)
1177 {
1178 daemon_smtp_port = string_from_gstring(new_smtp_port);
1179 DEBUG(D_any) debug_printf("daemon_smtp_port overridden by -oX:\n %s\n",
1180 daemon_smtp_port);
1181 }
1182
1183 if (new_local_interfaces)
1184 {
1185 local_interfaces = string_from_gstring(new_local_interfaces);
1186 local_iface_source = US"-oX data";
1187 DEBUG(D_any) debug_printf("local_interfaces overridden by -oX:\n %s\n",
1188 local_interfaces);
1189 }
1190 }
1191
1192 /* Create a list of default SMTP ports, to be used if local_interfaces
1193 contains entries without explicit ports. First count the number of ports, then
1194 build a translated list in a vector. */
1195
1196 list = daemon_smtp_port;
1197 sep = 0;
1198 while ((s = string_nextinlist(&list, &sep, big_buffer, big_buffer_size)))
1199 pct++;
1200 default_smtp_port = store_get((pct+1) * sizeof(int), FALSE);
1201 list = daemon_smtp_port;
1202 sep = 0;
1203 for (pct = 0;
1204 (s = string_nextinlist(&list, &sep, big_buffer, big_buffer_size));
1205 pct++)
1206 {
1207 if (isdigit(*s))
1208 {
1209 uschar *end;
1210 default_smtp_port[pct] = Ustrtol(s, &end, 0);
1211 if (end != s + Ustrlen(s))
1212 log_write(0, LOG_PANIC_DIE|LOG_CONFIG, "invalid SMTP port: %s", s);
1213 }
1214 else
1215 {
1216 struct servent *smtp_service = getservbyname(CS s, "tcp");
1217 if (!smtp_service)
1218 log_write(0, LOG_PANIC_DIE|LOG_CONFIG, "TCP port \"%s\" not found", s);
1219 default_smtp_port[pct] = ntohs(smtp_service->s_port);
1220 }
1221 }
1222 default_smtp_port[pct] = 0;
1223
1224 /* Check the list of TLS-on-connect ports and do name lookups if needed */
1225
1226 list = tls_in.on_connect_ports;
1227 sep = 0;
1228 while ((s = string_nextinlist(&list, &sep, big_buffer, big_buffer_size)))
1229 if (!isdigit(*s))
1230 {
1231 gstring * g = NULL;
1232
1233 list = tls_in.on_connect_ports;
1234 tls_in.on_connect_ports = NULL;
1235 sep = 0;
1236 while ((s = string_nextinlist(&list, &sep, big_buffer, big_buffer_size)))
1237 {
1238 if (!isdigit(*s))
1239 {
1240 struct servent * smtp_service = getservbyname(CS s, "tcp");
1241 if (!smtp_service)
1242 log_write(0, LOG_PANIC_DIE|LOG_CONFIG, "TCP port \"%s\" not found", s);
1243 s = string_sprintf("%d", (int)ntohs(smtp_service->s_port));
1244 }
1245 g = string_append_listele(g, ':', s);
1246 }
1247 if (g)
1248 tls_in.on_connect_ports = g->s;
1249 break;
1250 }
1251
1252 /* Create the list of local interfaces, possibly with ports included. This
1253 list may contain references to 0.0.0.0 and ::0 as wildcards. These special
1254 values are converted below. */
1255
1256 addresses = host_build_ifacelist(local_interfaces, local_iface_source);
1257
1258 /* In the list of IP addresses, convert 0.0.0.0 into an empty string, and ::0
1259 into the string ":". We use these to recognize wildcards in IPv4 and IPv6. In
1260 fact, many IP stacks recognize 0.0.0.0 and ::0 and handle them as wildcards
1261 anyway, but we need to know which are the wildcard addresses, and the shorter
1262 strings are neater.
1263
1264 In the same scan, fill in missing port numbers from the default list. When
1265 there is more than one item in the list, extra items are created. */
1266
1267 for (ipa = addresses; ipa; ipa = ipa->next)
1268 {
1269 if (Ustrcmp(ipa->address, "0.0.0.0") == 0)
1270 ipa->address[0] = 0;
1271 else if (Ustrcmp(ipa->address, "::0") == 0)
1272 {
1273 ipa->address[0] = ':';
1274 ipa->address[1] = 0;
1275 }
1276
1277 if (ipa->port > 0) continue;
1278
1279 if (daemon_smtp_port[0] <= 0)
1280 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "no port specified for interface "
1281 "%s and daemon_smtp_port is unset; cannot start daemon",
1282 ipa->address[0] == 0 ? US"\"all IPv4\"" :
1283 ipa->address[1] == 0 ? US"\"all IPv6\"" : ipa->address);
1284
1285 ipa->port = default_smtp_port[0];
1286 for (int i = 1; default_smtp_port[i] > 0; i++)
1287 {
1288 ip_address_item *new = store_get(sizeof(ip_address_item), FALSE);
1289
1290 memcpy(new->address, ipa->address, Ustrlen(ipa->address) + 1);
1291 new->port = default_smtp_port[i];
1292 new->next = ipa->next;
1293 ipa->next = new;
1294 ipa = new;
1295 }
1296 }
1297
1298 /* Scan the list of addresses for wildcards. If we find an IPv4 and an IPv6
1299 wildcard for the same port, ensure that (a) they are together and (b) the
1300 IPv6 address comes first. This makes handling the messy features easier, and
1301 also simplifies the construction of the "daemon started" log line. */
1302
1303 pipa = &addresses;
1304 for (ipa = addresses; ipa; pipa = &ipa->next, ipa = ipa->next)
1305 {
1306 ip_address_item *ipa2;
1307
1308 /* Handle an IPv4 wildcard */
1309
1310 if (ipa->address[0] == 0)
1311 for (ipa2 = ipa; ipa2->next; ipa2 = ipa2->next)
1312 {
1313 ip_address_item *ipa3 = ipa2->next;
1314 if (ipa3->address[0] == ':' &&
1315 ipa3->address[1] == 0 &&
1316 ipa3->port == ipa->port)
1317 {
1318 ipa2->next = ipa3->next;
1319 ipa3->next = ipa;
1320 *pipa = ipa3;
1321 break;
1322 }
1323 }
1324
1325 /* Handle an IPv6 wildcard. */
1326
1327 else if (ipa->address[0] == ':' && ipa->address[1] == 0)
1328 for (ipa2 = ipa; ipa2->next; ipa2 = ipa2->next)
1329 {
1330 ip_address_item *ipa3 = ipa2->next;
1331 if (ipa3->address[0] == 0 && ipa3->port == ipa->port)
1332 {
1333 ipa2->next = ipa3->next;
1334 ipa3->next = ipa->next;
1335 ipa->next = ipa3;
1336 ipa = ipa3;
1337 break;
1338 }
1339 }
1340 }
1341
1342 /* Get a vector to remember all the sockets in */
1343
1344 for (ipa = addresses; ipa; ipa = ipa->next)
1345 listen_socket_count++;
1346 listen_sockets = store_get(sizeof(int) * listen_socket_count, FALSE);
1347
1348 } /* daemon_listen but not inetd_wait_mode */
1349
1350 if (f.daemon_listen)
1351 {
1352
1353 /* Do a sanity check on the max connects value just to save us from getting
1354 a huge amount of store. */
1355
1356 if (smtp_accept_max > 4095) smtp_accept_max = 4096;
1357
1358 /* There's no point setting smtp_accept_queue unless it is less than the max
1359 connects limit. The configuration reader ensures that the max is set if the
1360 queue-only option is set. */
1361
1362 if (smtp_accept_queue > smtp_accept_max) smtp_accept_queue = 0;
1363
1364 /* Get somewhere to keep the list of SMTP accepting pids if we are keeping
1365 track of them for total number and queue/host limits. */
1366
1367 if (smtp_accept_max > 0)
1368 {
1369 smtp_slots = store_get(smtp_accept_max * sizeof(smtp_slot), FALSE);
1370 for (int i = 0; i < smtp_accept_max; i++) smtp_slots[i] = empty_smtp_slot;
1371 }
1372 }
1373
1374 /* The variable background_daemon is always false when debugging, but
1375 can also be forced false in order to keep a non-debugging daemon in the
1376 foreground. If background_daemon is true, close all open file descriptors that
1377 we know about, but then re-open stdin, stdout, and stderr to /dev/null. Also
1378 do this for inetd_wait mode.
1379
1380 This is protection against any called functions (in libraries, or in
1381 Perl, or whatever) that think they can write to stderr (or stdout). Before this
1382 was added, it was quite likely that an SMTP connection would use one of these
1383 file descriptors, in which case writing random stuff to it caused chaos.
1384
1385 Then disconnect from the controlling terminal, Most modern Unixes seem to have
1386 setsid() for getting rid of the controlling terminal. For any OS that doesn't,
1387 setsid() can be #defined as a no-op, or as something else. */
1388
1389 if (f.background_daemon || f.inetd_wait_mode)
1390 {
1391 log_close_all(); /* Just in case anything was logged earlier */
1392 search_tidyup(); /* Just in case any were used in reading the config. */
1393 (void)close(0); /* Get rid of stdin/stdout/stderr */
1394 (void)close(1);
1395 (void)close(2);
1396 exim_nullstd(); /* Connect stdin/stdout/stderr to /dev/null */
1397 log_stderr = NULL; /* So no attempt to copy paniclog output */
1398 }
1399
1400 if (f.background_daemon)
1401 {
1402 /* If the parent process of this one has pid == 1, we are re-initializing the
1403 daemon as the result of a SIGHUP. In this case, there is no need to do
1404 anything, because the controlling terminal has long gone. Otherwise, fork, in
1405 case current process is a process group leader (see 'man setsid' for an
1406 explanation) before calling setsid(). */
1407
1408 if (getppid() != 1)
1409 {
1410 pid_t pid = fork();
1411 if (pid < 0) log_write(0, LOG_MAIN|LOG_PANIC_DIE,
1412 "fork() failed when starting daemon: %s", strerror(errno));
1413 if (pid > 0) exit(EXIT_SUCCESS); /* in parent process, just exit */
1414 (void)setsid(); /* release controlling terminal */
1415 }
1416 }
1417
1418 /* We are now in the disconnected, daemon process (unless debugging). Set up
1419 the listening sockets if required. */
1420
1421 if (f.daemon_listen && !f.inetd_wait_mode)
1422 {
1423 int sk;
1424 ip_address_item *ipa;
1425
1426 /* For each IP address, create a socket, bind it to the appropriate port, and
1427 start listening. See comments above about IPv6 sockets that may or may not
1428 accept IPv4 calls when listening on all interfaces. We also have to cope with
1429 the case of a system with IPv6 libraries, but no IPv6 support in the kernel.
1430 listening, provided a wildcard IPv4 socket for the same port follows. */
1431
1432 for (ipa = addresses, sk = 0; sk < listen_socket_count; ipa = ipa->next, sk++)
1433 {
1434 BOOL wildcard;
1435 ip_address_item *ipa2;
1436 int af;
1437
1438 if (Ustrchr(ipa->address, ':') != NULL)
1439 {
1440 af = AF_INET6;
1441 wildcard = ipa->address[1] == 0;
1442 }
1443 else
1444 {
1445 af = AF_INET;
1446 wildcard = ipa->address[0] == 0;
1447 }
1448
1449 if ((listen_sockets[sk] = ip_socket(SOCK_STREAM, af)) < 0)
1450 {
1451 if (check_special_case(0, addresses, ipa, FALSE))
1452 {
1453 log_write(0, LOG_MAIN, "Failed to create IPv6 socket for wildcard "
1454 "listening (%s): will use IPv4", strerror(errno));
1455 goto SKIP_SOCKET;
1456 }
1457 log_write(0, LOG_PANIC_DIE, "IPv%c socket creation failed: %s",
1458 (af == AF_INET6)? '6' : '4', strerror(errno));
1459 }
1460
1461 /* If this is an IPv6 wildcard socket, set IPV6_V6ONLY if that option is
1462 available. Just log failure (can get protocol not available, just like
1463 socket creation can). */
1464
1465 #ifdef IPV6_V6ONLY
1466 if (af == AF_INET6 && wildcard &&
1467 setsockopt(listen_sockets[sk], IPPROTO_IPV6, IPV6_V6ONLY, CS (&on),
1468 sizeof(on)) < 0)
1469 log_write(0, LOG_MAIN, "Setting IPV6_V6ONLY on daemon's IPv6 wildcard "
1470 "socket failed (%s): carrying on without it", strerror(errno));
1471 #endif /* IPV6_V6ONLY */
1472
1473 /* Set SO_REUSEADDR so that the daemon can be restarted while a connection
1474 is being handled. Without this, a connection will prevent reuse of the
1475 smtp port for listening. */
1476
1477 if (setsockopt(listen_sockets[sk], SOL_SOCKET, SO_REUSEADDR,
1478 US (&on), sizeof(on)) < 0)
1479 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "setting SO_REUSEADDR on socket "
1480 "failed when starting daemon: %s", strerror(errno));
1481
1482 /* Set TCP_NODELAY; Exim does its own buffering. There is a switch to
1483 disable this because it breaks some broken clients. */
1484
1485 if (tcp_nodelay) setsockopt(listen_sockets[sk], IPPROTO_TCP, TCP_NODELAY,
1486 US (&on), sizeof(on));
1487
1488 /* Now bind the socket to the required port; if Exim is being restarted
1489 it may not always be possible to bind immediately, even with SO_REUSEADDR
1490 set, so try 10 times, waiting between each try. After 10 failures, we give
1491 up. In an IPv6 environment, if bind () fails with the error EADDRINUSE and
1492 we are doing wildcard IPv4 listening and there was a previous IPv6 wildcard
1493 address for the same port, ignore the error on the grounds that we must be
1494 in a system where the IPv6 socket accepts both kinds of call. This is
1495 necessary for (some release of) USAGI Linux; other IP stacks fail at the
1496 listen() stage instead. */
1497
1498 #ifdef TCP_FASTOPEN
1499 f.tcp_fastopen_ok = TRUE;
1500 #endif
1501 for(;;)
1502 {
1503 uschar *msg, *addr;
1504 if (ip_bind(listen_sockets[sk], af, ipa->address, ipa->port) >= 0) break;
1505 if (check_special_case(errno, addresses, ipa, TRUE))
1506 {
1507 DEBUG(D_any) debug_printf("wildcard IPv4 bind() failed after IPv6 "
1508 "listen() success; EADDRINUSE ignored\n");
1509 (void)close(listen_sockets[sk]);
1510 goto SKIP_SOCKET;
1511 }
1512 msg = US strerror(errno);
1513 addr = wildcard
1514 ? af == AF_INET6
1515 ? US"(any IPv6)"
1516 : US"(any IPv4)"
1517 : ipa->address;
1518 if (daemon_startup_retries <= 0)
1519 log_write(0, LOG_MAIN|LOG_PANIC_DIE,
1520 "socket bind() to port %d for address %s failed: %s: "
1521 "daemon abandoned", ipa->port, addr, msg);
1522 log_write(0, LOG_MAIN, "socket bind() to port %d for address %s "
1523 "failed: %s: waiting %s before trying again (%d more %s)",
1524 ipa->port, addr, msg, readconf_printtime(daemon_startup_sleep),
1525 daemon_startup_retries, (daemon_startup_retries > 1)? "tries" : "try");
1526 daemon_startup_retries--;
1527 sleep(daemon_startup_sleep);
1528 }
1529
1530 DEBUG(D_any)
1531 if (wildcard)
1532 debug_printf("listening on all interfaces (IPv%c) port %d\n",
1533 af == AF_INET6 ? '6' : '4', ipa->port);
1534 else
1535 debug_printf("listening on %s port %d\n", ipa->address, ipa->port);
1536
1537 #if defined(TCP_FASTOPEN) && !defined(__APPLE__)
1538 if ( f.tcp_fastopen_ok
1539 && setsockopt(listen_sockets[sk], IPPROTO_TCP, TCP_FASTOPEN,
1540 &smtp_connect_backlog, sizeof(smtp_connect_backlog)))
1541 {
1542 DEBUG(D_any) debug_printf("setsockopt FASTOPEN: %s\n", strerror(errno));
1543 f.tcp_fastopen_ok = FALSE;
1544 }
1545 #endif
1546
1547 /* Start listening on the bound socket, establishing the maximum backlog of
1548 connections that is allowed. On success, continue to the next address. */
1549
1550 if (listen(listen_sockets[sk], smtp_connect_backlog) >= 0)
1551 {
1552 #if defined(TCP_FASTOPEN) && defined(__APPLE__)
1553 if ( f.tcp_fastopen_ok
1554 && setsockopt(listen_sockets[sk], IPPROTO_TCP, TCP_FASTOPEN,
1555 &on, sizeof(on)))
1556 {
1557 DEBUG(D_any) debug_printf("setsockopt FASTOPEN: %s\n", strerror(errno));
1558 f.tcp_fastopen_ok = FALSE;
1559 }
1560 #endif
1561 continue;
1562 }
1563
1564 /* Listening has failed. In an IPv6 environment, as for bind(), if listen()
1565 fails with the error EADDRINUSE and we are doing IPv4 wildcard listening
1566 and there was a previous successful IPv6 wildcard listen on the same port,
1567 we want to ignore the error on the grounds that we must be in a system
1568 where the IPv6 socket accepts both kinds of call. */
1569
1570 if (!check_special_case(errno, addresses, ipa, TRUE))
1571 log_write(0, LOG_PANIC_DIE, "listen() failed on interface %s: %s",
1572 wildcard
1573 ? af == AF_INET6 ? US"(any IPv6)" : US"(any IPv4)" : ipa->address,
1574 strerror(errno));
1575
1576 DEBUG(D_any) debug_printf("wildcard IPv4 listen() failed after IPv6 "
1577 "listen() success; EADDRINUSE ignored\n");
1578 (void)close(listen_sockets[sk]);
1579
1580 /* Come here if there has been a problem with the socket which we
1581 are going to ignore. We remove the address from the chain, and back up the
1582 counts. */
1583
1584 SKIP_SOCKET:
1585 sk--; /* Back up the count */
1586 listen_socket_count--; /* Reduce the total */
1587 if (ipa == addresses) addresses = ipa->next; else
1588 {
1589 for (ipa2 = addresses; ipa2->next != ipa; ipa2 = ipa2->next);
1590 ipa2->next = ipa->next;
1591 ipa = ipa2;
1592 }
1593 } /* End of bind/listen loop for each address */
1594 } /* End of setup for listening */
1595
1596
1597 /* If we are not listening, we want to write a pid file only if -oP was
1598 explicitly given. */
1599
1600 else if (!override_pid_file_path)
1601 write_pid = FALSE;
1602
1603 /* Write the pid to a known file for assistance in identification, if required.
1604 We do this before giving up root privilege, because on some systems it is
1605 necessary to be root in order to write into the pid file directory. There's
1606 nothing to stop multiple daemons running, as long as no more than one listens
1607 on a given TCP/IP port on the same interface(s). However, in these
1608 circumstances it gets far too complicated to mess with pid file names
1609 automatically. Consequently, Exim 4 writes a pid file only
1610
1611 (a) When running in the test harness, or
1612 (b) When -bd is used and -oX is not used, or
1613 (c) When -oP is used to supply a path.
1614
1615 The variable daemon_write_pid is used to control this. */
1616
1617 if (f.running_in_test_harness || write_pid)
1618 {
1619 FILE *f;
1620
1621 set_pid_file_path();
1622 if ((f = modefopen(pid_file_path, "wb", 0644)))
1623 {
1624 (void)fprintf(f, "%d\n", (int)getpid());
1625 (void)fclose(f);
1626 DEBUG(D_any) debug_printf("pid written to %s\n", pid_file_path);
1627 }
1628 else
1629 DEBUG(D_any)
1630 debug_printf("%s\n", string_open_failed(errno, "pid file %s",
1631 pid_file_path));
1632 }
1633
1634 /* Set up the handler for SIGHUP, which causes a restart of the daemon. */
1635
1636 sighup_seen = FALSE;
1637 signal(SIGHUP, sighup_handler);
1638
1639 /* Give up root privilege at this point (assuming that exim_uid and exim_gid
1640 are not root). The third argument controls the running of initgroups().
1641 Normally we do this, in order to set up the groups for the Exim user. However,
1642 if we are not root at this time - some odd installations run that way - we
1643 cannot do this. */
1644
1645 exim_setugid(exim_uid, exim_gid, geteuid()==root_uid, US"running as a daemon");
1646
1647 /* Update the originator_xxx fields so that received messages as listed as
1648 coming from Exim, not whoever started the daemon. */
1649
1650 originator_uid = exim_uid;
1651 originator_gid = exim_gid;
1652 originator_login = (pw = getpwuid(exim_uid))
1653 ? string_copy_perm(US pw->pw_name, FALSE) : US"exim";
1654
1655 /* Get somewhere to keep the list of queue-runner pids if we are keeping track
1656 of them (and also if we are doing queue runs). */
1657
1658 if (queue_interval > 0 && local_queue_run_max > 0)
1659 {
1660 queue_pid_slots = store_get(local_queue_run_max * sizeof(pid_t), FALSE);
1661 for (int i = 0; i < local_queue_run_max; i++) queue_pid_slots[i] = 0;
1662 }
1663
1664 /* Set up the handler for termination of child processes, and the one
1665 telling us to die. */
1666
1667 sigchld_seen = FALSE;
1668 os_non_restarting_signal(SIGCHLD, main_sigchld_handler);
1669
1670 sigterm_seen = FALSE;
1671 os_non_restarting_signal(SIGTERM, main_sigterm_handler);
1672
1673 /* If we are to run the queue periodically, pretend the alarm has just gone
1674 off. This will cause the first queue-runner to get kicked off straight away. */
1675
1676 sigalrm_seen = (queue_interval > 0);
1677
1678 /* Log the start up of a daemon - at least one of listening or queue running
1679 must be set up. */
1680
1681 if (f.inetd_wait_mode)
1682 {
1683 uschar *p = big_buffer;
1684
1685 if (inetd_wait_timeout >= 0)
1686 sprintf(CS p, "terminating after %d seconds", inetd_wait_timeout);
1687 else
1688 sprintf(CS p, "with no wait timeout");
1689
1690 log_write(0, LOG_MAIN,
1691 "exim %s daemon started: pid=%d, launched with listening socket, %s",
1692 version_string, getpid(), big_buffer);
1693 set_process_info("daemon(%s): pre-listening socket", version_string);
1694
1695 /* set up the timeout logic */
1696 sigalrm_seen = 1;
1697 }
1698
1699 else if (f.daemon_listen)
1700 {
1701 int smtp_ports = 0;
1702 int smtps_ports = 0;
1703 ip_address_item * ipa;
1704 uschar * p;
1705 uschar * qinfo = queue_interval > 0
1706 ? string_sprintf("-q%s", readconf_printtime(queue_interval))
1707 : US"no queue runs";
1708
1709 /* Build a list of listening addresses in big_buffer, but limit it to 10
1710 items. The style is for backwards compatibility.
1711
1712 It is now possible to have some ports listening for SMTPS (the old,
1713 deprecated protocol that starts TLS without using STARTTLS), and others
1714 listening for standard SMTP. Keep their listings separate. */
1715
1716 for (int j = 0, i; j < 2; j++)
1717 {
1718 for (i = 0, ipa = addresses; i < 10 && ipa; i++, ipa = ipa->next)
1719 {
1720 /* First time round, look for SMTP ports; second time round, look for
1721 SMTPS ports. Build IP+port strings. */
1722
1723 if (host_is_tls_on_connect_port(ipa->port) == (j > 0))
1724 {
1725 if (j == 0)
1726 smtp_ports++;
1727 else
1728 smtps_ports++;
1729
1730 /* Now the information about the port (and sometimes interface) */
1731
1732 if (ipa->address[0] == ':' && ipa->address[1] == 0)
1733 { /* v6 wildcard */
1734 if (ipa->next && ipa->next->address[0] == 0 &&
1735 ipa->next->port == ipa->port)
1736 {
1737 ipa->log = string_sprintf(" port %d (IPv6 and IPv4)", ipa->port);
1738 (ipa = ipa->next)->log = NULL;
1739 }
1740 else if (ipa->v6_include_v4)
1741 ipa->log = string_sprintf(" port %d (IPv6 with IPv4)", ipa->port);
1742 else
1743 ipa->log = string_sprintf(" port %d (IPv6)", ipa->port);
1744 }
1745 else if (ipa->address[0] == 0) /* v4 wildcard */
1746 ipa->log = string_sprintf(" port %d (IPv4)", ipa->port);
1747 else /* check for previously-seen IP */
1748 {
1749 ip_address_item * i2;
1750 for (i2 = addresses; i2 != ipa; i2 = i2->next)
1751 if ( host_is_tls_on_connect_port(i2->port) == (j > 0)
1752 && Ustrcmp(ipa->address, i2->address) == 0
1753 )
1754 { /* found; append port to list */
1755 for (p = i2->log; *p; ) p++; /* end of existing string */
1756 if (*--p == '}') *p = '\0'; /* drop EOL */
1757 while (isdigit(*--p)) ; /* char before port */
1758
1759 i2->log = *p == ':' /* no list yet? */
1760 ? string_sprintf("%.*s{%s,%d}",
1761 (int)(p - i2->log + 1), i2->log, p+1, ipa->port)
1762 : string_sprintf("%s,%d}", i2->log, ipa->port);
1763 ipa->log = NULL;
1764 break;
1765 }
1766 if (i2 == ipa) /* first-time IP */
1767 ipa->log = string_sprintf(" [%s]:%d", ipa->address, ipa->port);
1768 }
1769 }
1770 }
1771 }
1772
1773 p = big_buffer;
1774 for (int j = 0, i; j < 2; j++)
1775 {
1776 /* First time round, look for SMTP ports; second time round, look for
1777 SMTPS ports. For the first one of each, insert leading text. */
1778
1779 if (j == 0)
1780 {
1781 if (smtp_ports > 0)
1782 p += sprintf(CS p, "SMTP on");
1783 }
1784 else
1785 if (smtps_ports > 0)
1786 p += sprintf(CS p, "%sSMTPS on",
1787 smtp_ports == 0 ? "" : " and for ");
1788
1789 /* Now the information about the port (and sometimes interface) */
1790
1791 for (i = 0, ipa = addresses; i < 10 && ipa; i++, ipa = ipa->next)
1792 if (host_is_tls_on_connect_port(ipa->port) == (j > 0))
1793 if (ipa->log)
1794 p += sprintf(CS p, "%s", ipa->log);
1795
1796 if (ipa)
1797 p += sprintf(CS p, " ...");
1798 }
1799
1800 log_write(0, LOG_MAIN,
1801 "exim %s daemon started: pid=%d, %s, listening for %s",
1802 version_string, getpid(), qinfo, big_buffer);
1803 set_process_info("daemon(%s): %s, listening for %s",
1804 version_string, qinfo, big_buffer);
1805 }
1806
1807 else
1808 {
1809 uschar * s = *queue_name
1810 ? string_sprintf("-qG%s/%s", queue_name, readconf_printtime(queue_interval))
1811 : string_sprintf("-q%s", readconf_printtime(queue_interval));
1812 log_write(0, LOG_MAIN,
1813 "exim %s daemon started: pid=%d, %s, not listening for SMTP",
1814 version_string, getpid(), s);
1815 set_process_info("daemon(%s): %s, not listening", version_string, s);
1816 }
1817
1818 /* Do any work it might be useful to amortize over our children
1819 (eg: compile regex) */
1820
1821 dns_pattern_init();
1822 smtp_deliver_init(); /* Used for callouts */
1823
1824 #ifndef DISABLE_DKIM
1825 {
1826 # ifdef MEASURE_TIMING
1827 struct timeval t0;
1828 gettimeofday(&t0, NULL);
1829 # endif
1830 dkim_exim_init();
1831 # ifdef MEASURE_TIMING
1832 report_time_since(&t0, US"dkim_exim_init (delta)");
1833 # endif
1834 }
1835 #endif
1836
1837 #ifdef WITH_CONTENT_SCAN
1838 malware_init();
1839 #endif
1840 #ifdef SUPPORT_SPF
1841 spf_init();
1842 #endif
1843
1844 /* Close the log so it can be renamed and moved. In the few cases below where
1845 this long-running process writes to the log (always exceptional conditions), it
1846 closes the log afterwards, for the same reason. */
1847
1848 log_close_all();
1849
1850 DEBUG(D_any) debug_print_ids(US"daemon running with");
1851
1852 /* Any messages accepted via this route are going to be SMTP. */
1853
1854 smtp_input = TRUE;
1855
1856 #ifdef MEASURE_TIMING
1857 report_time_since(&timestamp_startup, US"daemon loop start"); /* testcase 0022 */
1858 #endif
1859
1860 /* Enter the never-ending loop... */
1861
1862 for (;;)
1863 {
1864 #if HAVE_IPV6
1865 struct sockaddr_in6 accepted;
1866 #else
1867 struct sockaddr_in accepted;
1868 #endif
1869
1870 EXIM_SOCKLEN_T len;
1871 pid_t pid;
1872
1873 if (sigterm_seen)
1874 daemon_die(); /* Does not return */
1875
1876 /* This code is placed first in the loop, so that it gets obeyed at the
1877 start, before the first wait, for the queue-runner case, so that the first
1878 one can be started immediately.
1879
1880 The other option is that we have an inetd wait timeout specified to -bw. */
1881
1882 if (sigalrm_seen)
1883 {
1884 if (inetd_wait_timeout > 0)
1885 {
1886 time_t resignal_interval = inetd_wait_timeout;
1887
1888 if (last_connection_time == (time_t)0)
1889 {
1890 DEBUG(D_any)
1891 debug_printf("inetd wait timeout expired, but still not seen first message, ignoring\n");
1892 }
1893 else
1894 {
1895 time_t now = time(NULL);
1896 if (now == (time_t)-1)
1897 {
1898 DEBUG(D_any) debug_printf("failed to get time: %s\n", strerror(errno));
1899 }
1900 else
1901 {
1902 if ((now - last_connection_time) >= inetd_wait_timeout)
1903 {
1904 DEBUG(D_any)
1905 debug_printf("inetd wait timeout %d expired, ending daemon\n",
1906 inetd_wait_timeout);
1907 log_write(0, LOG_MAIN, "exim %s daemon terminating, inetd wait timeout reached.\n",
1908 version_string);
1909 exit(EXIT_SUCCESS);
1910 }
1911 else
1912 {
1913 resignal_interval -= (now - last_connection_time);
1914 }
1915 }
1916 }
1917
1918 sigalrm_seen = FALSE;
1919 ALARM(resignal_interval);
1920 }
1921
1922 else
1923 {
1924 DEBUG(D_any) debug_printf("SIGALRM received\n");
1925
1926 /* Do a full queue run in a child process, if required, unless we already
1927 have enough queue runners on the go. If we are not running as root, a
1928 re-exec is required. */
1929
1930 if (queue_interval > 0 &&
1931 (local_queue_run_max <= 0 || queue_run_count < local_queue_run_max))
1932 {
1933 if ((pid = fork()) == 0)
1934 {
1935 DEBUG(D_any) debug_printf("Starting queue-runner: pid %d\n",
1936 (int)getpid());
1937
1938 /* Disable debugging if it's required only for the daemon process. We
1939 leave the above message, because it ties up with the "child ended"
1940 debugging messages. */
1941
1942 if (f.debug_daemon) debug_selector = 0;
1943
1944 /* Close any open listening sockets in the child */
1945
1946 for (int sk = 0; sk < listen_socket_count; sk++)
1947 (void)close(listen_sockets[sk]);
1948
1949 /* Reset SIGHUP and SIGCHLD in the child in both cases. */
1950
1951 signal(SIGHUP, SIG_DFL);
1952 signal(SIGCHLD, SIG_DFL);
1953 signal(SIGTERM, SIG_DFL);
1954
1955 /* Re-exec if privilege has been given up, unless deliver_drop_
1956 privilege is set. Reset SIGALRM before exec(). */
1957
1958 if (geteuid() != root_uid && !deliver_drop_privilege)
1959 {
1960 uschar opt[8];
1961 uschar *p = opt;
1962 uschar *extra[5];
1963 int extracount = 1;
1964
1965 signal(SIGALRM, SIG_DFL);
1966 *p++ = '-';
1967 *p++ = 'q';
1968 if (f.queue_2stage) *p++ = 'q';
1969 if (f.queue_run_first_delivery) *p++ = 'i';
1970 if (f.queue_run_force) *p++ = 'f';
1971 if (f.deliver_force_thaw) *p++ = 'f';
1972 if (f.queue_run_local) *p++ = 'l';
1973 *p = 0;
1974 extra[0] = queue_name
1975 ? string_sprintf("%sG%s", opt, queue_name) : opt;
1976
1977 /* If -R or -S were on the original command line, ensure they get
1978 passed on. */
1979
1980 if (deliver_selectstring)
1981 {
1982 extra[extracount++] = f.deliver_selectstring_regex ? US"-Rr" : US"-R";
1983 extra[extracount++] = deliver_selectstring;
1984 }
1985
1986 if (deliver_selectstring_sender)
1987 {
1988 extra[extracount++] = f.deliver_selectstring_sender_regex
1989 ? US"-Sr" : US"-S";
1990 extra[extracount++] = deliver_selectstring_sender;
1991 }
1992
1993 /* Overlay this process with a new execution. */
1994
1995 (void)child_exec_exim(CEE_EXEC_PANIC, FALSE, NULL, TRUE, extracount,
1996 extra[0], extra[1], extra[2], extra[3], extra[4]);
1997
1998 /* Control never returns here. */
1999 }
2000
2001 /* No need to re-exec; SIGALRM remains set to the default handler */
2002
2003 queue_run(NULL, NULL, FALSE);
2004 exim_underbar_exit(EXIT_SUCCESS);
2005 }
2006
2007 if (pid < 0)
2008 {
2009 log_write(0, LOG_MAIN|LOG_PANIC, "daemon: fork of queue-runner "
2010 "process failed: %s", strerror(errno));
2011 log_close_all();
2012 }
2013 else
2014 {
2015 for (int i = 0; i < local_queue_run_max; ++i)
2016 if (queue_pid_slots[i] <= 0)
2017 {
2018 queue_pid_slots[i] = pid;
2019 queue_run_count++;
2020 break;
2021 }
2022 DEBUG(D_any) debug_printf("%d queue-runner process%s running\n",
2023 queue_run_count, queue_run_count == 1 ? "" : "es");
2024 }
2025 }
2026
2027 /* Reset the alarm clock */
2028
2029 sigalrm_seen = FALSE;
2030 ALARM(queue_interval);
2031 }
2032
2033 } /* sigalrm_seen */
2034
2035
2036 /* Sleep till a connection happens if listening, and handle the connection if
2037 that is why we woke up. The FreeBSD operating system requires the use of
2038 select() before accept() because the latter function is not interrupted by
2039 a signal, and we want to wake up for SIGCHLD and SIGALRM signals. Some other
2040 OS do notice signals in accept() but it does no harm to have the select()
2041 in for all of them - and it won't then be a lurking problem for ports to
2042 new OS. In fact, the later addition of listening on specific interfaces only
2043 requires this way of working anyway. */
2044
2045 if (f.daemon_listen)
2046 {
2047 int lcount, select_errno;
2048 int max_socket = 0;
2049 BOOL select_failed = FALSE;
2050 fd_set select_listen;
2051
2052 FD_ZERO(&select_listen);
2053 for (int sk = 0; sk < listen_socket_count; sk++)
2054 {
2055 FD_SET(listen_sockets[sk], &select_listen);
2056 if (listen_sockets[sk] > max_socket) max_socket = listen_sockets[sk];
2057 }
2058
2059 DEBUG(D_any) debug_printf("Listening...\n");
2060
2061 /* In rare cases we may have had a SIGCHLD signal in the time between
2062 setting the handler (below) and getting back here. If so, pretend that the
2063 select() was interrupted so that we reap the child. This might still leave
2064 a small window when a SIGCHLD could get lost. However, since we use SIGCHLD
2065 only to do the reaping more quickly, it shouldn't result in anything other
2066 than a delay until something else causes a wake-up. */
2067
2068 if (sigchld_seen)
2069 {
2070 lcount = -1;
2071 errno = EINTR;
2072 }
2073 else
2074 lcount = select(max_socket + 1, (SELECT_ARG2_TYPE *)&select_listen,
2075 NULL, NULL, NULL);
2076
2077 if (lcount < 0)
2078 {
2079 select_failed = TRUE;
2080 lcount = 1;
2081 }
2082
2083 /* Clean up any subprocesses that may have terminated. We need to do this
2084 here so that smtp_accept_max_per_host works when a connection to that host
2085 has completed, and we are about to accept a new one. When this code was
2086 later in the sequence, a new connection could be rejected, even though an
2087 old one had just finished. Preserve the errno from any select() failure for
2088 the use of the common select/accept error processing below. */
2089
2090 select_errno = errno;
2091 handle_ending_processes();
2092 errno = select_errno;
2093
2094 #ifndef DISABLE_TLS
2095 /* Create or rotate any required keys */
2096 tls_daemon_init();
2097 #endif
2098
2099 /* Loop for all the sockets that are currently ready to go. If select
2100 actually failed, we have set the count to 1 and select_failed=TRUE, so as
2101 to use the common error code for select/accept below. */
2102
2103 while (lcount-- > 0)
2104 {
2105 int accept_socket = -1;
2106
2107 if (!select_failed)
2108 for (int sk = 0; sk < listen_socket_count; sk++)
2109 if (FD_ISSET(listen_sockets[sk], &select_listen))
2110 {
2111 len = sizeof(accepted);
2112 accept_socket = accept(listen_sockets[sk],
2113 (struct sockaddr *)&accepted, &len);
2114 FD_CLR(listen_sockets[sk], &select_listen);
2115 break;
2116 }
2117
2118 /* If select or accept has failed and this was not caused by an
2119 interruption, log the incident and try again. With asymmetric TCP/IP
2120 routing errors such as "No route to network" have been seen here. Also
2121 "connection reset by peer" has been seen. These cannot be classed as
2122 disastrous errors, but they could fill up a lot of log. The code in smail
2123 crashes the daemon after 10 successive failures of accept, on the grounds
2124 that some OS fail continuously. Exim originally followed suit, but this
2125 appears to have caused problems. Now it just keeps going, but instead of
2126 logging each error, it batches them up when they are continuous. */
2127
2128 if (accept_socket < 0 && errno != EINTR)
2129 {
2130 if (accept_retry_count == 0)
2131 {
2132 accept_retry_errno = errno;
2133 accept_retry_select_failed = select_failed;
2134 }
2135 else
2136 {
2137 if (errno != accept_retry_errno ||
2138 select_failed != accept_retry_select_failed ||
2139 accept_retry_count >= 50)
2140 {
2141 log_write(0, LOG_MAIN | ((accept_retry_count >= 50)? LOG_PANIC : 0),
2142 "%d %s() failure%s: %s",
2143 accept_retry_count,
2144 accept_retry_select_failed? "select" : "accept",
2145 (accept_retry_count == 1)? "" : "s",
2146 strerror(accept_retry_errno));
2147 log_close_all();
2148 accept_retry_count = 0;
2149 accept_retry_errno = errno;
2150 accept_retry_select_failed = select_failed;
2151 }
2152 }
2153 accept_retry_count++;
2154 }
2155
2156 else
2157 {
2158 if (accept_retry_count > 0)
2159 {
2160 log_write(0, LOG_MAIN, "%d %s() failure%s: %s",
2161 accept_retry_count,
2162 accept_retry_select_failed? "select" : "accept",
2163 (accept_retry_count == 1)? "" : "s",
2164 strerror(accept_retry_errno));
2165 log_close_all();
2166 accept_retry_count = 0;
2167 }
2168 }
2169
2170 /* If select/accept succeeded, deal with the connection. */
2171
2172 if (accept_socket >= 0)
2173 {
2174 if (inetd_wait_timeout)
2175 last_connection_time = time(NULL);
2176 handle_smtp_call(listen_sockets, listen_socket_count, accept_socket,
2177 (struct sockaddr *)&accepted);
2178 }
2179 }
2180 }
2181
2182 /* If not listening, then just sleep for the queue interval. If we woke
2183 up early the last time for some other signal, it won't matter because
2184 the alarm signal will wake at the right time. This code originally used
2185 sleep() but it turns out that on the FreeBSD system, sleep() is not inter-
2186 rupted by signals, so it wasn't waking up for SIGALRM or SIGCHLD. Luckily
2187 select() can be used as an interruptible sleep() on all versions of Unix. */
2188
2189 else
2190 {
2191 struct timeval tv;
2192 tv.tv_sec = queue_interval;
2193 tv.tv_usec = 0;
2194 select(0, NULL, NULL, NULL, &tv);
2195 handle_ending_processes();
2196 }
2197
2198 /* Re-enable the SIGCHLD handler if it has been run. It can't do it
2199 for itself, because it isn't doing the waiting itself. */
2200
2201 if (sigchld_seen)
2202 {
2203 sigchld_seen = FALSE;
2204 os_non_restarting_signal(SIGCHLD, main_sigchld_handler);
2205 }
2206
2207 /* Handle being woken by SIGHUP. We know at this point that the result
2208 of accept() has been dealt with, so we can re-exec exim safely, first
2209 closing the listening sockets so that they can be reused. Cancel any pending
2210 alarm in case it is just about to go off, and set SIGHUP to be ignored so
2211 that another HUP in quick succession doesn't clobber the new daemon before it
2212 gets going. All log files get closed by the close-on-exec flag; however, if
2213 the exec fails, we need to close the logs. */
2214
2215 if (sighup_seen)
2216 {
2217 log_write(0, LOG_MAIN, "pid %d: SIGHUP received: re-exec daemon",
2218 getpid());
2219 for (int sk = 0; sk < listen_socket_count; sk++)
2220 (void)close(listen_sockets[sk]);
2221 ALARM_CLR(0);
2222 signal(SIGHUP, SIG_IGN);
2223 sighup_argv[0] = exim_path;
2224 exim_nullstd();
2225 execv(CS exim_path, (char *const *)sighup_argv);
2226 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "pid %d: exec of %s failed: %s",
2227 getpid(), exim_path, strerror(errno));
2228 log_close_all();
2229 }
2230
2231 } /* End of main loop */
2232
2233 /* Control never reaches here */
2234 }
2235
2236 /* vi: aw ai sw=2
2237 */
2238 /* End of exim_daemon.c */