aa36a5dc9361a713cfd5b8256491cda5b4bd7f18
[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 *************************************************/
131
132 static void
133 close_daemon_sockets(int daemon_notifier_fd,
134 int * listen_sockets, int listen_socket_count)
135 {
136 if (daemon_notifier_fd >= 0) (void) close(daemon_notifier_fd);
137 for (int i = 0; i < listen_socket_count; i++) (void) close(listen_sockets[i]);
138 }
139
140
141 /*************************************************
142 * Handle a connected SMTP call *
143 *************************************************/
144
145 /* This function is called when an SMTP connection has been accepted.
146 If there are too many, give an error message and close down. Otherwise
147 spin off a sub-process to handle the call. The list of listening sockets
148 is required so that they can be closed in the sub-process. Take care not to
149 leak store in this process - reset the stacking pool at the end.
150
151 Arguments:
152 listen_sockets sockets which are listening for incoming calls
153 listen_socket_count count of listening sockets
154 accept_socket socket of the current accepted call
155 accepted socket information about the current call
156
157 Returns: nothing
158 */
159
160 static void
161 handle_smtp_call(int *listen_sockets, int listen_socket_count,
162 int accept_socket, struct sockaddr *accepted)
163 {
164 pid_t pid;
165 union sockaddr_46 interface_sockaddr;
166 EXIM_SOCKLEN_T ifsize = sizeof(interface_sockaddr);
167 int dup_accept_socket = -1;
168 int max_for_this_host = 0;
169 int save_log_selector = *log_selector;
170 gstring * whofrom;
171
172 rmark reset_point = store_mark();
173
174 /* Make the address available in ASCII representation, and also fish out
175 the remote port. */
176
177 sender_host_address = host_ntoa(-1, accepted, NULL, &sender_host_port);
178 DEBUG(D_any) debug_printf("Connection request from %s port %d\n",
179 sender_host_address, sender_host_port);
180
181 /* Set up the output stream, check the socket has duplicated, and set up the
182 input stream. These operations fail only the exceptional circumstances. Note
183 that never_error() won't use smtp_out if it is NULL. */
184
185 if (!(smtp_out = fdopen(accept_socket, "wb")))
186 {
187 never_error(US"daemon: fdopen() for smtp_out failed", US"", errno);
188 goto ERROR_RETURN;
189 }
190
191 if ((dup_accept_socket = dup(accept_socket)) < 0)
192 {
193 never_error(US"daemon: couldn't dup socket descriptor",
194 US"Connection setup failed", errno);
195 goto ERROR_RETURN;
196 }
197
198 if (!(smtp_in = fdopen(dup_accept_socket, "rb")))
199 {
200 never_error(US"daemon: fdopen() for smtp_in failed",
201 US"Connection setup failed", errno);
202 goto ERROR_RETURN;
203 }
204
205 /* Get the data for the local interface address. Panic for most errors, but
206 "connection reset by peer" just means the connection went away. */
207
208 if (getsockname(accept_socket, (struct sockaddr *)(&interface_sockaddr),
209 &ifsize) < 0)
210 {
211 log_write(0, LOG_MAIN | ((errno == ECONNRESET)? 0 : LOG_PANIC),
212 "getsockname() failed: %s", strerror(errno));
213 smtp_printf("421 Local problem: getsockname() failed; please try again later\r\n", FALSE);
214 goto ERROR_RETURN;
215 }
216
217 interface_address = host_ntoa(-1, &interface_sockaddr, NULL, &interface_port);
218 DEBUG(D_interface) debug_printf("interface address=%s port=%d\n",
219 interface_address, interface_port);
220
221 /* Build a string identifying the remote host and, if requested, the port and
222 the local interface data. This is for logging; at the end of this function the
223 memory is reclaimed. */
224
225 whofrom = string_append(NULL, 3, "[", sender_host_address, "]");
226
227 if (LOGGING(incoming_port))
228 whofrom = string_fmt_append(whofrom, ":%d", sender_host_port);
229
230 if (LOGGING(incoming_interface))
231 whofrom = string_fmt_append(whofrom, " I=[%s]:%d",
232 interface_address, interface_port);
233
234 (void) string_from_gstring(whofrom); /* Terminate the newly-built string */
235
236 /* Check maximum number of connections. We do not check for reserved
237 connections or unacceptable hosts here. That is done in the subprocess because
238 it might take some time. */
239
240 if (smtp_accept_max > 0 && smtp_accept_count >= smtp_accept_max)
241 {
242 DEBUG(D_any) debug_printf("rejecting SMTP connection: count=%d max=%d\n",
243 smtp_accept_count, smtp_accept_max);
244 smtp_printf("421 Too many concurrent SMTP connections; "
245 "please try again later.\r\n", FALSE);
246 log_write(L_connection_reject,
247 LOG_MAIN, "Connection from %s refused: too many connections",
248 whofrom->s);
249 goto ERROR_RETURN;
250 }
251
252 /* If a load limit above which only reserved hosts are acceptable is defined,
253 get the load average here, and if there are in fact no reserved hosts, do
254 the test right away (saves a fork). If there are hosts, do the check in the
255 subprocess because it might take time. */
256
257 if (smtp_load_reserve >= 0)
258 {
259 load_average = OS_GETLOADAVG();
260 if (smtp_reserve_hosts == NULL && load_average > smtp_load_reserve)
261 {
262 DEBUG(D_any) debug_printf("rejecting SMTP connection: load average = %.2f\n",
263 (double)load_average/1000.0);
264 smtp_printf("421 Too much load; please try again later.\r\n", FALSE);
265 log_write(L_connection_reject,
266 LOG_MAIN, "Connection from %s refused: load average = %.2f",
267 whofrom->s, (double)load_average/1000.0);
268 goto ERROR_RETURN;
269 }
270 }
271
272 /* Check that one specific host (strictly, IP address) is not hogging
273 resources. This is done here to prevent a denial of service attack by someone
274 forcing you to fork lots of times before denying service. The value of
275 smtp_accept_max_per_host is a string which is expanded. This makes it possible
276 to provide host-specific limits according to $sender_host address, but because
277 this is in the daemon mainline, only fast expansions (such as inline address
278 checks) should be used. The documentation is full of warnings. */
279
280 if (smtp_accept_max_per_host != NULL)
281 {
282 uschar *expanded = expand_string(smtp_accept_max_per_host);
283 if (expanded == NULL)
284 {
285 if (!f.expand_string_forcedfail)
286 log_write(0, LOG_MAIN|LOG_PANIC, "expansion of smtp_accept_max_per_host "
287 "failed for %s: %s", whofrom->s, expand_string_message);
288 }
289 /* For speed, interpret a decimal number inline here */
290 else
291 {
292 uschar *s = expanded;
293 while (isdigit(*s))
294 max_for_this_host = max_for_this_host * 10 + *s++ - '0';
295 if (*s != 0)
296 log_write(0, LOG_MAIN|LOG_PANIC, "expansion of smtp_accept_max_per_host "
297 "for %s contains non-digit: %s", whofrom->s, expanded);
298 }
299 }
300
301 /* If we have fewer connections than max_for_this_host, we can skip the tedious
302 per host_address checks. Note that at this stage smtp_accept_count contains the
303 count of *other* connections, not including this one. */
304
305 if ((max_for_this_host > 0) &&
306 (smtp_accept_count >= max_for_this_host))
307 {
308 int host_accept_count = 0;
309 int other_host_count = 0; /* keep a count of non matches to optimise */
310
311 for (int i = 0; i < smtp_accept_max; ++i)
312 if (smtp_slots[i].host_address)
313 {
314 if (Ustrcmp(sender_host_address, smtp_slots[i].host_address) == 0)
315 host_accept_count++;
316 else
317 other_host_count++;
318
319 /* Testing all these strings is expensive - see if we can drop out
320 early, either by hitting the target, or finding there are not enough
321 connections left to make the target. */
322
323 if ((host_accept_count >= max_for_this_host) ||
324 ((smtp_accept_count - other_host_count) < max_for_this_host))
325 break;
326 }
327
328 if (host_accept_count >= max_for_this_host)
329 {
330 DEBUG(D_any) debug_printf("rejecting SMTP connection: too many from this "
331 "IP address: count=%d max=%d\n",
332 host_accept_count, max_for_this_host);
333 smtp_printf("421 Too many concurrent SMTP connections "
334 "from this IP address; please try again later.\r\n", FALSE);
335 log_write(L_connection_reject,
336 LOG_MAIN, "Connection from %s refused: too many connections "
337 "from that IP address", whofrom->s);
338 goto ERROR_RETURN;
339 }
340 }
341
342 /* OK, the connection count checks have been passed. Before we can fork the
343 accepting process, we must first log the connection if requested. This logging
344 used to happen in the subprocess, but doing that means that the value of
345 smtp_accept_count can be out of step by the time it is logged. So we have to do
346 the logging here and accept the performance cost. Note that smtp_accept_count
347 hasn't yet been incremented to take account of this connection.
348
349 In order to minimize the cost (because this is going to happen for every
350 connection), do a preliminary selector test here. This saves ploughing through
351 the generalized logging code each time when the selector is false. If the
352 selector is set, check whether the host is on the list for logging. If not,
353 arrange to unset the selector in the subprocess. */
354
355 if (LOGGING(smtp_connection))
356 {
357 uschar *list = hosts_connection_nolog;
358 memset(sender_host_cache, 0, sizeof(sender_host_cache));
359 if (list != NULL && verify_check_host(&list) == OK)
360 save_log_selector &= ~L_smtp_connection;
361 else
362 log_write(L_smtp_connection, LOG_MAIN, "SMTP connection from %s "
363 "(TCP/IP connection count = %d)", whofrom->s, smtp_accept_count + 1);
364 }
365
366 /* Now we can fork the accepting process; do a lookup tidy, just in case any
367 expansion above did a lookup. */
368
369 search_tidyup();
370 pid = fork();
371
372 /* Handle the child process */
373
374 if (pid == 0)
375 {
376 int i;
377 int queue_only_reason = 0;
378 int old_pool = store_pool;
379 int save_debug_selector = debug_selector;
380 BOOL local_queue_only;
381 BOOL session_local_queue_only;
382 #ifdef SA_NOCLDWAIT
383 struct sigaction act;
384 #endif
385
386 smtp_accept_count++; /* So that it includes this process */
387
388 /* May have been modified for the subprocess */
389
390 *log_selector = save_log_selector;
391
392 /* Get the local interface address into permanent store */
393
394 store_pool = POOL_PERM;
395 interface_address = string_copy(interface_address);
396 store_pool = old_pool;
397
398 /* Check for a tls-on-connect port */
399
400 if (host_is_tls_on_connect_port(interface_port)) tls_in.on_connect = TRUE;
401
402 /* Expand smtp_active_hostname if required. We do not do this any earlier,
403 because it may depend on the local interface address (indeed, that is most
404 likely what it depends on.) */
405
406 smtp_active_hostname = primary_hostname;
407 if (raw_active_hostname)
408 {
409 uschar * nah = expand_string(raw_active_hostname);
410 if (!nah)
411 {
412 if (!f.expand_string_forcedfail)
413 {
414 log_write(0, LOG_MAIN|LOG_PANIC, "failed to expand \"%s\" "
415 "(smtp_active_hostname): %s", raw_active_hostname,
416 expand_string_message);
417 smtp_printf("421 Local configuration error; "
418 "please try again later.\r\n", FALSE);
419 mac_smtp_fflush();
420 search_tidyup();
421 exim_underbar_exit(EXIT_FAILURE, US"conn-accept");
422 }
423 }
424 else if (*nah) smtp_active_hostname = nah;
425 }
426
427 /* Initialize the queueing flags */
428
429 queue_check_only();
430 session_local_queue_only = queue_only;
431
432 /* Close the listening sockets, and set the SIGCHLD handler to SIG_IGN.
433 We also attempt to set things up so that children are automatically reaped,
434 but just in case this isn't available, there's a paranoid waitpid() in the
435 loop too (except for systems where we are sure it isn't needed). See the more
436 extensive comment before the reception loop in exim.c for a fuller
437 explanation of this logic. */
438
439 close_daemon_sockets(daemon_notifier_fd, listen_sockets, listen_socket_count);
440
441 /* Set FD_CLOEXEC on the SMTP socket. We don't want any rogue child processes
442 to be able to communicate with them, under any circumstances. */
443 (void)fcntl(accept_socket, F_SETFD,
444 fcntl(accept_socket, F_GETFD) | FD_CLOEXEC);
445 (void)fcntl(dup_accept_socket, F_SETFD,
446 fcntl(dup_accept_socket, F_GETFD) | FD_CLOEXEC);
447
448 #ifdef SA_NOCLDWAIT
449 act.sa_handler = SIG_IGN;
450 sigemptyset(&(act.sa_mask));
451 act.sa_flags = SA_NOCLDWAIT;
452 sigaction(SIGCHLD, &act, NULL);
453 #else
454 signal(SIGCHLD, SIG_IGN);
455 #endif
456 signal(SIGTERM, SIG_DFL);
457
458 /* Attempt to get an id from the sending machine via the RFC 1413
459 protocol. We do this in the sub-process in order not to hold up the
460 main process if there is any delay. Then set up the fullhost information
461 in case there is no HELO/EHLO.
462
463 If debugging is enabled only for the daemon, we must turn if off while
464 finding the id, but turn it on again afterwards so that information about the
465 incoming connection is output. */
466
467 if (f.debug_daemon) debug_selector = 0;
468 verify_get_ident(IDENT_PORT);
469 host_build_sender_fullhost();
470 debug_selector = save_debug_selector;
471
472 DEBUG(D_any)
473 debug_printf("Process %d is handling incoming connection from %s\n",
474 (int)getpid(), sender_fullhost);
475
476 /* Now disable debugging permanently if it's required only for the daemon
477 process. */
478
479 if (f.debug_daemon) debug_selector = 0;
480
481 /* If there are too many child processes for immediate delivery,
482 set the session_local_queue_only flag, which is initialized from the
483 configured value and may therefore already be TRUE. Leave logging
484 till later so it will have a message id attached. Note that there is no
485 possibility of re-calculating this per-message, because the value of
486 smtp_accept_count does not change in this subprocess. */
487
488 if (smtp_accept_queue > 0 && smtp_accept_count > smtp_accept_queue)
489 {
490 session_local_queue_only = TRUE;
491 queue_only_reason = 1;
492 }
493
494 /* Handle the start of the SMTP session, then loop, accepting incoming
495 messages from the SMTP connection. The end will come at the QUIT command,
496 when smtp_setup_msg() returns 0. A break in the connection causes the
497 process to die (see accept.c).
498
499 NOTE: We do *not* call smtp_log_no_mail() if smtp_start_session() fails,
500 because a log line has already been written for all its failure exists
501 (usually "connection refused: <reason>") and writing another one is
502 unnecessary clutter. */
503
504 if (!smtp_start_session())
505 {
506 mac_smtp_fflush();
507 search_tidyup();
508 exim_underbar_exit(EXIT_SUCCESS, US"conn-smtp");
509 }
510
511 for (;;)
512 {
513 int rc;
514 message_id[0] = 0; /* Clear out any previous message_id */
515 reset_point = store_mark(); /* Save current store high water point */
516
517 DEBUG(D_any)
518 debug_printf("Process %d is ready for new message\n", (int)getpid());
519
520 /* Smtp_setup_msg() returns 0 on QUIT or if the call is from an
521 unacceptable host or if an ACL "drop" command was triggered, -1 on
522 connection lost, and +1 on validly reaching DATA. Receive_msg() almost
523 always returns TRUE when smtp_input is true; just retry if no message was
524 accepted (can happen for invalid message parameters). However, it can yield
525 FALSE if the connection was forcibly dropped by the DATA ACL. */
526
527 if ((rc = smtp_setup_msg()) > 0)
528 {
529 BOOL ok = receive_msg(FALSE);
530 search_tidyup(); /* Close cached databases */
531 if (!ok) /* Connection was dropped */
532 {
533 cancel_cutthrough_connection(TRUE, US"receive dropped");
534 mac_smtp_fflush();
535 smtp_log_no_mail(); /* Log no mail if configured */
536 exim_underbar_exit(EXIT_SUCCESS, US"conn-receive");
537 }
538 if (message_id[0] == 0) continue; /* No message was accepted */
539 }
540 else
541 {
542 if (smtp_out)
543 {
544 int fd = fileno(smtp_in);
545 uschar buf[128];
546
547 mac_smtp_fflush();
548 /* drain socket, for clean TCP FINs */
549 if (fcntl(fd, F_SETFL, O_NONBLOCK) == 0)
550 for(int i = 16; read(fd, buf, sizeof(buf)) > 0 && i > 0; ) i--;
551 }
552 cancel_cutthrough_connection(TRUE, US"message setup dropped");
553 search_tidyup();
554 smtp_log_no_mail(); /* Log no mail if configured */
555
556 /*XXX should we pause briefly, hoping that the client will be the
557 active TCP closer hence get the TCP_WAIT endpoint? */
558 DEBUG(D_receive) debug_printf("SMTP>>(close on process exit)\n");
559 exim_underbar_exit(rc ? EXIT_FAILURE : EXIT_SUCCESS, US"conn-setup");
560 }
561
562 /* Show the recipients when debugging */
563
564 DEBUG(D_receive)
565 {
566 if (sender_address)
567 debug_printf("Sender: %s\n", sender_address);
568 if (recipients_list)
569 {
570 debug_printf("Recipients:\n");
571 for (int i = 0; i < recipients_count; i++)
572 debug_printf(" %s\n", recipients_list[i].address);
573 }
574 }
575
576 /* A message has been accepted. Clean up any previous delivery processes
577 that have completed and are defunct, on systems where they don't go away
578 by themselves (see comments when setting SIG_IGN above). On such systems
579 (if any) these delivery processes hang around after termination until
580 the next message is received. */
581
582 #ifndef SIG_IGN_WORKS
583 while (waitpid(-1, NULL, WNOHANG) > 0);
584 #endif
585
586 /* Reclaim up the store used in accepting this message */
587
588 {
589 int r = receive_messagecount;
590 BOOL q = f.queue_only_policy;
591 smtp_reset(reset_point);
592 reset_point = NULL;
593 f.queue_only_policy = q;
594 receive_messagecount = r;
595 }
596
597 /* If queue_only is set or if there are too many incoming connections in
598 existence, session_local_queue_only will be TRUE. If it is not, check
599 whether we have received too many messages in this session for immediate
600 delivery. */
601
602 if (!session_local_queue_only &&
603 smtp_accept_queue_per_connection > 0 &&
604 receive_messagecount > smtp_accept_queue_per_connection)
605 {
606 session_local_queue_only = TRUE;
607 queue_only_reason = 2;
608 }
609
610 /* Initialize local_queue_only from session_local_queue_only. If it is not
611 true, and queue_only_load is set, check that the load average is below it.
612 If local_queue_only is set by this means, we also set if for the session if
613 queue_only_load_latch is true (the default). This means that, once set,
614 local_queue_only remains set for any subsequent messages on the same SMTP
615 connection. This is a deliberate choice; even though the load average may
616 fall, it doesn't seem right to deliver later messages on the same call when
617 not delivering earlier ones. However, the are special circumstances such as
618 very long-lived connections from scanning appliances where this is not the
619 best strategy. In such cases, queue_only_load_latch should be set false. */
620
621 if ( !(local_queue_only = session_local_queue_only)
622 && queue_only_load >= 0
623 && (local_queue_only = (load_average = OS_GETLOADAVG()) > queue_only_load)
624 )
625 {
626 queue_only_reason = 3;
627 if (queue_only_load_latch) session_local_queue_only = TRUE;
628 }
629
630 /* Log the queueing here, when it will get a message id attached, but
631 not if queue_only is set (case 0). */
632
633 if (local_queue_only) switch(queue_only_reason)
634 {
635 case 1: log_write(L_delay_delivery,
636 LOG_MAIN, "no immediate delivery: too many connections "
637 "(%d, max %d)", smtp_accept_count, smtp_accept_queue);
638 break;
639
640 case 2: log_write(L_delay_delivery,
641 LOG_MAIN, "no immediate delivery: more than %d messages "
642 "received in one connection", smtp_accept_queue_per_connection);
643 break;
644
645 case 3: log_write(L_delay_delivery,
646 LOG_MAIN, "no immediate delivery: load average %.2f",
647 (double)load_average/1000.0);
648 break;
649 }
650
651 /* If a delivery attempt is required, spin off a new process to handle it.
652 If we are not root, we have to re-exec exim unless deliveries are being
653 done unprivileged. */
654
655 else if ( (!f.queue_only_policy || f.queue_smtp)
656 && !f.deliver_freeze)
657 {
658 pid_t dpid;
659
660 /* Before forking, ensure that the C output buffer is flushed. Otherwise
661 anything that it in it will get duplicated, leading to duplicate copies
662 of the pending output. */
663
664 mac_smtp_fflush();
665
666 if ((dpid = fork()) == 0)
667 {
668 (void)fclose(smtp_in);
669 (void)fclose(smtp_out);
670
671 /* Don't ever molest the parent's SSL connection, but do clean up
672 the data structures if necessary. */
673
674 #ifndef DISABLE_TLS
675 tls_close(NULL, TLS_NO_SHUTDOWN);
676 #endif
677
678 /* Reset SIGHUP and SIGCHLD in the child in both cases. */
679
680 signal(SIGHUP, SIG_DFL);
681 signal(SIGCHLD, SIG_DFL);
682 signal(SIGTERM, SIG_DFL);
683
684 if (geteuid() != root_uid && !deliver_drop_privilege)
685 {
686 signal(SIGALRM, SIG_DFL);
687 delivery_re_exec(CEE_EXEC_PANIC);
688 /* Control does not return here. */
689 }
690
691 /* No need to re-exec; SIGALRM remains set to the default handler */
692
693 (void) deliver_message(message_id, FALSE, FALSE);
694 search_tidyup();
695 exim_underbar_exit(EXIT_SUCCESS, US"deliver_msg");
696 }
697
698 if (dpid > 0)
699 {
700 release_cutthrough_connection(US"passed for delivery");
701 DEBUG(D_any) debug_printf("forked delivery process %d\n", (int)dpid);
702 }
703 else
704 {
705 cancel_cutthrough_connection(TRUE, US"delivery fork failed");
706 log_write(0, LOG_MAIN|LOG_PANIC, "daemon: delivery process fork "
707 "failed: %s", strerror(errno));
708 }
709 }
710 }
711 }
712
713
714 /* Carrying on in the parent daemon process... Can't do much if the fork
715 failed. Otherwise, keep count of the number of accepting processes and
716 remember the pid for ticking off when the child completes. */
717
718 if (pid < 0)
719 never_error(US"daemon: accept process fork failed", US"Fork failed", errno);
720 else
721 {
722 for (int i = 0; i < smtp_accept_max; ++i)
723 if (smtp_slots[i].pid <= 0)
724 {
725 smtp_slots[i].pid = pid;
726 /* Connection closes come asyncronously, so we cannot stack this store */
727 if (smtp_accept_max_per_host)
728 smtp_slots[i].host_address = string_copy_malloc(sender_host_address);
729 smtp_accept_count++;
730 break;
731 }
732 DEBUG(D_any) debug_printf("%d SMTP accept process%s running\n",
733 smtp_accept_count, smtp_accept_count == 1 ? "" : "es");
734 }
735
736 /* Get here via goto in error cases */
737
738 ERROR_RETURN:
739
740 /* Close the streams associated with the socket which will also close the
741 socket fds in this process. We can't do anything if fclose() fails, but
742 logging brings it to someone's attention. However, "connection reset by peer"
743 isn't really a problem, so skip that one. On Solaris, a dropped connection can
744 manifest itself as a broken pipe, so drop that one too. If the streams don't
745 exist, something went wrong while setting things up. Make sure the socket
746 descriptors are closed, in order to drop the connection. */
747
748 if (smtp_out)
749 {
750 if (fclose(smtp_out) != 0 && errno != ECONNRESET && errno != EPIPE)
751 log_write(0, LOG_MAIN|LOG_PANIC, "daemon: fclose(smtp_out) failed: %s",
752 strerror(errno));
753 smtp_out = NULL;
754 }
755 else (void)close(accept_socket);
756
757 if (smtp_in)
758 {
759 if (fclose(smtp_in) != 0 && errno != ECONNRESET && errno != EPIPE)
760 log_write(0, LOG_MAIN|LOG_PANIC, "daemon: fclose(smtp_in) failed: %s",
761 strerror(errno));
762 smtp_in = NULL;
763 }
764 else (void)close(dup_accept_socket);
765
766 /* Release any store used in this process, including the store used for holding
767 the incoming host address and an expanded active_hostname. */
768
769 log_close_all();
770 interface_address =
771 sender_host_address = NULL;
772 store_reset(reset_point);
773 sender_host_address = NULL;
774 }
775
776
777
778
779 /*************************************************
780 * Check wildcard listen special cases *
781 *************************************************/
782
783 /* This function is used when binding and listening on lists of addresses and
784 ports. It tests for special cases of wildcard listening, when IPv4 and IPv6
785 sockets may interact in different ways in different operating systems. It is
786 passed an error number, the list of listening addresses, and the current
787 address. Two checks are available: for a previous wildcard IPv6 address, or for
788 a following wildcard IPv4 address, in both cases on the same port.
789
790 In practice, pairs of wildcard addresses should be adjacent in the address list
791 because they are sorted that way below.
792
793 Arguments:
794 eno the error number
795 addresses the list of addresses
796 ipa the current IP address
797 back if TRUE, check for previous wildcard IPv6 address
798 if FALSE, check for a following wildcard IPv4 address
799
800 Returns: TRUE or FALSE
801 */
802
803 static BOOL
804 check_special_case(int eno, ip_address_item *addresses, ip_address_item *ipa,
805 BOOL back)
806 {
807 ip_address_item *ipa2;
808
809 /* For the "back" case, if the failure was "address in use" for a wildcard IPv4
810 address, seek a previous IPv6 wildcard address on the same port. As it is
811 previous, it must have been successfully bound and be listening. Flag it as a
812 "6 including 4" listener. */
813
814 if (back)
815 {
816 if (eno != EADDRINUSE || ipa->address[0] != 0) return FALSE;
817 for (ipa2 = addresses; ipa2 != ipa; ipa2 = ipa2->next)
818 {
819 if (ipa2->address[1] == 0 && ipa2->port == ipa->port)
820 {
821 ipa2->v6_include_v4 = TRUE;
822 return TRUE;
823 }
824 }
825 }
826
827 /* For the "forward" case, if the current address is a wildcard IPv6 address,
828 we seek a following wildcard IPv4 address on the same port. */
829
830 else
831 {
832 if (ipa->address[0] != ':' || ipa->address[1] != 0) return FALSE;
833 for (ipa2 = ipa->next; ipa2 != NULL; ipa2 = ipa2->next)
834 if (ipa2->address[0] == 0 && ipa->port == ipa2->port) return TRUE;
835 }
836
837 return FALSE;
838 }
839
840
841
842
843 /*************************************************
844 * Handle terminating subprocesses *
845 *************************************************/
846
847 /* Handle the termination of child processes. Theoretically, this need be done
848 only when sigchld_seen is TRUE, but rumour has it that some systems lose
849 SIGCHLD signals at busy times, so to be on the safe side, this function is
850 called each time round. It shouldn't be too expensive.
851
852 Arguments: none
853 Returns: nothing
854 */
855
856 static void
857 handle_ending_processes(void)
858 {
859 int status;
860 pid_t pid;
861
862 while ((pid = waitpid(-1, &status, WNOHANG)) > 0)
863 {
864 DEBUG(D_any)
865 {
866 debug_printf("child %d ended: status=0x%x\n", (int)pid, status);
867 #ifdef WCOREDUMP
868 if (WIFEXITED(status))
869 debug_printf(" normal exit, %d\n", WEXITSTATUS(status));
870 else if (WIFSIGNALED(status))
871 debug_printf(" signal exit, signal %d%s\n", WTERMSIG(status),
872 WCOREDUMP(status) ? " (core dumped)" : "");
873 #endif
874 }
875
876 /* If it's a listening daemon for which we are keeping track of individual
877 subprocesses, deal with an accepting process that has terminated. */
878
879 if (smtp_slots)
880 {
881 int i;
882 for (i = 0; i < smtp_accept_max; i++)
883 if (smtp_slots[i].pid == pid)
884 {
885 if (smtp_slots[i].host_address)
886 store_free(smtp_slots[i].host_address);
887 smtp_slots[i] = empty_smtp_slot;
888 if (--smtp_accept_count < 0) smtp_accept_count = 0;
889 DEBUG(D_any) debug_printf("%d SMTP accept process%s now running\n",
890 smtp_accept_count, (smtp_accept_count == 1)? "" : "es");
891 break;
892 }
893 if (i < smtp_accept_max) continue; /* Found an accepting process */
894 }
895
896 /* If it wasn't an accepting process, see if it was a queue-runner
897 process that we are tracking. */
898
899 if (queue_pid_slots)
900 {
901 int max = atoi(CS expand_string(queue_run_max));
902 for (int i = 0; i < max; i++)
903 if (queue_pid_slots[i] == pid)
904 {
905 queue_pid_slots[i] = 0;
906 if (--queue_run_count < 0) queue_run_count = 0;
907 DEBUG(D_any) debug_printf("%d queue-runner process%s now running\n",
908 queue_run_count, (queue_run_count == 1)? "" : "es");
909 break;
910 }
911 }
912 }
913 }
914
915
916
917 static void
918 set_pid_file_path(void)
919 {
920 if (override_pid_file_path)
921 pid_file_path = override_pid_file_path;
922
923 if (!*pid_file_path)
924 pid_file_path = string_sprintf("%s/exim-daemon.pid", spool_directory);
925 }
926
927
928 /* Remove the daemon's pidfile. Note: runs with root privilege,
929 as a direct child of the daemon. Does not return. */
930
931 void
932 delete_pid_file(void)
933 {
934 uschar * daemon_pid = string_sprintf("%d\n", (int)getppid());
935 FILE * f;
936
937 set_pid_file_path();
938 if ((f = Ufopen(pid_file_path, "rb")))
939 {
940 if ( fgets(CS big_buffer, big_buffer_size, f)
941 && Ustrcmp(daemon_pid, big_buffer) == 0
942 )
943 if (Uunlink(pid_file_path) == 0)
944 {
945 DEBUG(D_any)
946 debug_printf("%s unlink: %s\n", pid_file_path, strerror(errno));
947 }
948 else
949 DEBUG(D_any)
950 debug_printf("unlinked %s\n", pid_file_path);
951 fclose(f);
952 }
953 else
954 DEBUG(D_any)
955 debug_printf("%s\n", string_open_failed(errno, "pid file %s",
956 pid_file_path));
957 exim_exit(EXIT_SUCCESS, US"pid file remover");
958 }
959
960
961 /* Called by the daemon; exec a child to get the pid file deleted
962 since we may require privs for the containing directory */
963
964 static void
965 daemon_die(void)
966 {
967 int pid;
968
969 if (daemon_notifier_fd >= 0)
970 {
971 close(daemon_notifier_fd);
972 daemon_notifier_fd = -1;
973 #ifndef EXIM_HAVE_ABSTRACT_UNIX_SOCKETS
974 {
975 uschar * s = expand_string(notifier_socket);
976 DEBUG(D_any) debug_printf("unlinking notifier socket %s\n", s);
977 Uunlink(s);
978 }
979 #endif
980 }
981
982 if (f.running_in_test_harness || write_pid)
983 {
984 if ((pid = fork()) == 0)
985 {
986 if (override_pid_file_path)
987 (void)child_exec_exim(CEE_EXEC_PANIC, FALSE, NULL, FALSE, 3,
988 "-oP", override_pid_file_path, "-oPX");
989 else
990 (void)child_exec_exim(CEE_EXEC_PANIC, FALSE, NULL, FALSE, 1, "-oPX");
991
992 /* Control never returns here. */
993 }
994 if (pid > 0)
995 child_close(pid, 1);
996 }
997 exim_exit(EXIT_SUCCESS, US"daemon");
998 }
999
1000
1001 /*************************************************
1002 * Listener socket for local work prompts *
1003 *************************************************/
1004
1005 static void
1006 daemon_notifier_socket(void)
1007 {
1008 int fd;
1009 const uschar * where;
1010 struct sockaddr_un sa_un = {.sun_family = AF_UNIX};
1011 int len;
1012
1013 if (override_local_interfaces && !override_pid_file_path)
1014 {
1015 DEBUG(D_any)
1016 debug_printf("-oX used without -oP so not creating notifier socket\n");
1017 return;
1018 }
1019
1020 DEBUG(D_any) debug_printf("creating notifier socket\n");
1021
1022 #ifdef SOCK_CLOEXEC
1023 if ((fd = socket(PF_UNIX, SOCK_DGRAM|SOCK_CLOEXEC, 0)) < 0)
1024 { where = US"socket"; goto bad; }
1025 #else
1026 if ((fd = socket(PF_UNIX, SOCK_DGRAM, 0)) < 0)
1027 { where = US"socket"; goto bad; }
1028 (void)fcntl(fd, F_SETFD, fcntl(fd, F_GETFD) | FD_CLOEXEC);
1029 #endif
1030
1031 #ifdef EXIM_HAVE_ABSTRACT_UNIX_SOCKETS
1032 sa_un.sun_path[0] = 0; /* Abstract local socket addr - Linux-specific? */
1033 len = offsetof(struct sockaddr_un, sun_path) + 1
1034 + snprintf(sa_un.sun_path+1, sizeof(sa_un.sun_path)-1, "%s",
1035 expand_string(notifier_socket));
1036 DEBUG(D_any) debug_printf(" @%s\n", sa_un.sun_path+1);
1037 #else /* filesystem-visible and persistent; will neeed removal */
1038 len = offsetof(struct sockaddr_un, sun_path)
1039 + snprintf(sa_un.sun_path, sizeof(sa_un.sun_path), "%s",
1040 expand_string(notifier_socket));
1041 DEBUG(D_any) debug_printf(" %s\n", sa_un.sun_path);
1042 #endif
1043
1044 if (bind(fd, (const struct sockaddr *)&sa_un, len) < 0)
1045 { where = US"bind"; goto bad; }
1046
1047 #ifdef SO_PASSCRED /* Linux */
1048 if (setsockopt(fd, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on)) < 0)
1049 { where = US"SO_PASSCRED"; goto bad2; }
1050 #elif defined(LOCAL_CREDS) /* FreeBSD-ish */
1051 if (setsockopt(fd, 0, LOCAL_CREDS, &on, sizeof(on)) < 0)
1052 { where = US"LOCAL_CREDS"; goto bad2; }
1053 #endif
1054
1055 /* debug_printf("%s: fd %d\n", __FUNCTION__, fd); */
1056 daemon_notifier_fd = fd;
1057 return;
1058
1059 bad2:
1060 #ifndef EXIM_HAVE_ABSTRACT_UNIX_SOCKETS
1061 Uunlink(sa_un.sun_path);
1062 #endif
1063 bad:
1064 log_write(0, LOG_MAIN|LOG_PANIC, "%s %s: %s",
1065 __FUNCTION__, where, strerror(errno));
1066 close(fd);
1067 return;
1068 }
1069
1070
1071 static uschar queuerun_msgid[MESSAGE_ID_LENGTH+1];
1072
1073 /* Return TRUE if a sigalrm should be emulated */
1074 static BOOL
1075 daemon_notification(void)
1076 {
1077 uschar buf[256], cbuf[256];
1078 struct sockaddr_un sa_un;
1079 struct iovec iov = {.iov_base = buf, .iov_len = sizeof(buf)-1};
1080 struct msghdr msg = { .msg_name = &sa_un,
1081 .msg_namelen = sizeof(sa_un),
1082 .msg_iov = &iov,
1083 .msg_iovlen = 1,
1084 .msg_control = cbuf,
1085 .msg_controllen = sizeof(cbuf)
1086 };
1087 ssize_t sz;
1088 struct cmsghdr * cp;
1089
1090 buf[sizeof(buf)-1] = 0;
1091 if ((sz = recvmsg(daemon_notifier_fd, &msg, 0)) <= 0) return FALSE;
1092 if (sz >= sizeof(buf)) return FALSE;
1093
1094 #ifdef notdef
1095 debug_printf("addrlen %d\n", msg.msg_namelen);
1096 #endif
1097 DEBUG(D_queue_run) debug_printf("%s from addr '%s%.*s'\n", __FUNCTION__,
1098 *sa_un.sun_path ? "" : "@",
1099 (int)msg.msg_namelen - (*sa_un.sun_path ? 0 : 1),
1100 sa_un.sun_path + (*sa_un.sun_path ? 0 : 1));
1101
1102 /* Refuse to handle the item unless the peer has good credentials */
1103 #ifdef SCM_CREDENTIALS
1104 # define EXIM_SCM_CR_TYPE SCM_CREDENTIALS
1105 #elif defined(LOCAL_CREDS) && defined(SCM_CREDS)
1106 # define EXIM_SCM_CR_TYPE SCM_CREDS
1107 #else
1108 /* The OS has no way to get the creds of the caller (for a unix/datagram socket.
1109 Punt; don't try to check. */
1110 #endif
1111
1112 #ifdef EXIM_SCM_CR_TYPE
1113 for (struct cmsghdr * cp = CMSG_FIRSTHDR(&msg);
1114 cp;
1115 cp = CMSG_NXTHDR(&msg, cp))
1116 if (cp->cmsg_level == SOL_SOCKET && cp->cmsg_type == EXIM_SCM_CR_TYPE)
1117 {
1118 # ifdef SCM_CREDENTIALS /* Linux */
1119 struct ucred * cr = (struct ucred *) CMSG_DATA(cp);
1120 if (cr->uid && cr->uid != exim_uid)
1121 {
1122 DEBUG(D_queue_run) debug_printf("%s: sender creds pid %d uid %d gid %d\n",
1123 __FUNCTION__, (int)cr->pid, (int)cr->uid, (int)cr->gid);
1124 return FALSE;
1125 }
1126 # elif defined(LOCAL_CREDS) /* BSD-ish */
1127 struct sockcred * cr = (struct sockcred *) CMSG_DATA(cp);
1128 if (cr->sc_uid && cr->sc_uid != exim_uid)
1129 {
1130 DEBUG(D_queue_run) debug_printf("%s: sender creds pid ??? uid %d gid %d\n",
1131 __FUNCTION__, (int)cr->sc_uid, (int)cr->sc_gid);
1132 return FALSE;
1133 }
1134 # endif
1135 break;
1136 }
1137 #endif
1138
1139 buf[sz] = 0;
1140 switch (buf[0])
1141 {
1142 #ifdef EXPERIMENTAL_QUEUE_RAMP
1143 case NOTIFY_MSG_QRUN:
1144 /* this should be a message_id */
1145 DEBUG(D_queue_run)
1146 debug_printf("%s: qrunner trigger: %s\n", __FUNCTION__, buf+1);
1147 memcpy(queuerun_msgid, buf+1, MESSAGE_ID_LENGTH+1);
1148 return TRUE;
1149 #endif /*EXPERIMENTAL_QUEUE_RAMP*/
1150
1151 case NOTIFY_QUEUE_SIZE_REQ:
1152 {
1153 uschar buf[16];
1154 int len = snprintf(CS buf, sizeof(buf), "%u", queue_count_cached());
1155
1156 DEBUG(D_queue_run)
1157 debug_printf("%s: queue size request: %s\n", __FUNCTION__, buf);
1158
1159 if (sendto(daemon_notifier_fd, buf, len, 0,
1160 (const struct sockaddr *)&sa_un, msg.msg_namelen) < 0)
1161 log_write(0, LOG_MAIN|LOG_PANIC,
1162 "%s: sendto: %s\n", __FUNCTION__, strerror(errno));
1163 return FALSE;
1164 }
1165 }
1166 return FALSE;
1167 }
1168
1169
1170 /*************************************************
1171 * Exim Daemon Mainline *
1172 *************************************************/
1173
1174 /* The daemon can do two jobs, either of which is optional:
1175
1176 (1) Listens for incoming SMTP calls and spawns off a sub-process to handle
1177 each one. This is requested by the -bd option, with -oX specifying the SMTP
1178 port on which to listen (for testing).
1179
1180 (2) Spawns a queue-running process every so often. This is controlled by the
1181 -q option with a an interval time. (If no time is given, a single queue run
1182 is done from the main function, and control doesn't get here.)
1183
1184 Root privilege is required in order to attach to port 25. Some systems require
1185 it when calling socket() rather than bind(). To cope with all cases, we run as
1186 root for both socket() and bind(). Some systems also require root in order to
1187 write to the pid file directory. This function must therefore be called as root
1188 if it is to work properly in all circumstances. Once the socket is bound and
1189 the pid file written, root privilege is given up if there is an exim uid.
1190
1191 There are no arguments to this function, and it never returns. */
1192
1193 void
1194 daemon_go(void)
1195 {
1196 struct passwd *pw;
1197 int *listen_sockets = NULL;
1198 int listen_socket_count = 0;
1199 ip_address_item *addresses = NULL;
1200 time_t last_connection_time = (time_t)0;
1201 int local_queue_run_max = atoi(CS expand_string(queue_run_max));
1202
1203 /* If any debugging options are set, turn on the D_pid bit so that all
1204 debugging lines get the pid added. */
1205
1206 DEBUG(D_any|D_v) debug_selector |= D_pid;
1207
1208 if (f.inetd_wait_mode)
1209 {
1210 listen_socket_count = 1;
1211 listen_sockets = store_get(sizeof(int), FALSE);
1212 (void) close(3);
1213 if (dup2(0, 3) == -1)
1214 log_write(0, LOG_MAIN|LOG_PANIC_DIE,
1215 "failed to dup inetd socket safely away: %s", strerror(errno));
1216
1217 listen_sockets[0] = 3;
1218 (void) close(0);
1219 (void) close(1);
1220 (void) close(2);
1221 exim_nullstd();
1222
1223 if (debug_file == stderr)
1224 {
1225 /* need a call to log_write before call to open debug_file, so that
1226 log.c:file_path has been initialised. This is unfortunate. */
1227 log_write(0, LOG_MAIN, "debugging Exim in inetd wait mode starting");
1228
1229 fclose(debug_file);
1230 debug_file = NULL;
1231 exim_nullstd(); /* re-open fd2 after we just closed it again */
1232 debug_logging_activate(US"-wait", NULL);
1233 }
1234
1235 DEBUG(D_any) debug_printf("running in inetd wait mode\n");
1236
1237 /* As per below, when creating sockets ourselves, we handle tcp_nodelay for
1238 our own buffering; we assume though that inetd set the socket REUSEADDR. */
1239
1240 if (tcp_nodelay)
1241 if (setsockopt(3, IPPROTO_TCP, TCP_NODELAY, US &on, sizeof(on)))
1242 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "failed to set socket NODELAY: %s",
1243 strerror(errno));
1244 }
1245
1246
1247 if (f.inetd_wait_mode || f.daemon_listen)
1248 {
1249 /* If any option requiring a load average to be available during the
1250 reception of a message is set, call os_getloadavg() while we are root
1251 for those OS for which this is necessary the first time it is called (in
1252 order to perform an "open" on the kernel memory file). */
1253
1254 #ifdef LOAD_AVG_NEEDS_ROOT
1255 if (queue_only_load >= 0 || smtp_load_reserve >= 0 ||
1256 (deliver_queue_load_max >= 0 && deliver_drop_privilege))
1257 (void)os_getloadavg();
1258 #endif
1259 }
1260
1261
1262 /* Do the preparation for setting up a listener on one or more interfaces, and
1263 possible on various ports. This is controlled by the combination of
1264 local_interfaces (which can set IP addresses and ports) and daemon_smtp_port
1265 (which is a list of default ports to use for those items in local_interfaces
1266 that do not specify a port). The -oX command line option can be used to
1267 override one or both of these options.
1268
1269 If local_interfaces is not set, the default is to listen on all interfaces.
1270 When it is set, it can include "all IPvx interfaces" as an item. This is useful
1271 when different ports are in use.
1272
1273 It turns out that listening on all interfaces is messy in an IPv6 world,
1274 because several different implementation approaches have been taken. This code
1275 is now supposed to work with all of them. The point of difference is whether an
1276 IPv6 socket that is listening on all interfaces will receive incoming IPv4
1277 calls or not. We also have to cope with the case when IPv6 libraries exist, but
1278 there is no IPv6 support in the kernel.
1279
1280 . On Solaris, an IPv6 socket will accept IPv4 calls, and give them as mapped
1281 addresses. However, if an IPv4 socket is also listening on all interfaces,
1282 calls are directed to the appropriate socket.
1283
1284 . On (some versions of) Linux, an IPv6 socket will accept IPv4 calls, and
1285 give them as mapped addresses, but an attempt also to listen on an IPv4
1286 socket on all interfaces causes an error.
1287
1288 . On OpenBSD, an IPv6 socket will not accept IPv4 calls. You have to set up
1289 two sockets if you want to accept both kinds of call.
1290
1291 . FreeBSD is like OpenBSD, but it has the IPV6_V6ONLY socket option, which
1292 can be turned off, to make it behave like the versions of Linux described
1293 above.
1294
1295 . I heard a report that the USAGI IPv6 stack for Linux has implemented
1296 IPV6_V6ONLY.
1297
1298 So, what we do when IPv6 is supported is as follows:
1299
1300 (1) After it is set up, the list of interfaces is scanned for wildcard
1301 addresses. If an IPv6 and an IPv4 wildcard are both found for the same
1302 port, the list is re-arranged so that they are together, with the IPv6
1303 wildcard first.
1304
1305 (2) If the creation of a wildcard IPv6 socket fails, we just log the error and
1306 carry on if an IPv4 wildcard socket for the same port follows later in the
1307 list. This allows Exim to carry on in the case when the kernel has no IPv6
1308 support.
1309
1310 (3) Having created an IPv6 wildcard socket, we try to set IPV6_V6ONLY if that
1311 option is defined. However, if setting fails, carry on regardless (but log
1312 the incident).
1313
1314 (4) If binding or listening on an IPv6 wildcard socket fails, it is a serious
1315 error.
1316
1317 (5) If binding or listening on an IPv4 wildcard socket fails with the error
1318 EADDRINUSE, and a previous interface was an IPv6 wildcard for the same
1319 port (which must have succeeded or we wouldn't have got this far), we
1320 assume we are in the situation where just a single socket is permitted,
1321 and ignore the error.
1322
1323 Phew!
1324
1325 The preparation code decodes options and sets up the relevant data. We do this
1326 first, so that we can return non-zero if there are any syntax errors, and also
1327 write to stderr. */
1328
1329 if (f.daemon_listen && !f.inetd_wait_mode)
1330 {
1331 int *default_smtp_port;
1332 int sep;
1333 int pct = 0;
1334 uschar *s;
1335 const uschar * list;
1336 uschar *local_iface_source = US"local_interfaces";
1337 ip_address_item *ipa;
1338 ip_address_item **pipa;
1339
1340 /* If -oX was used, disable the writing of a pid file unless -oP was
1341 explicitly used to force it. Then scan the string given to -oX. Any items
1342 that contain neither a dot nor a colon are used to override daemon_smtp_port.
1343 Any other items are used to override local_interfaces. */
1344
1345 if (override_local_interfaces)
1346 {
1347 gstring * new_smtp_port = NULL;
1348 gstring * new_local_interfaces = NULL;
1349
1350 if (!override_pid_file_path) write_pid = FALSE;
1351
1352 list = override_local_interfaces;
1353 sep = 0;
1354 while ((s = string_nextinlist(&list, &sep, big_buffer, big_buffer_size)))
1355 {
1356 uschar joinstr[4];
1357 gstring ** gp = Ustrpbrk(s, ".:") ? &new_local_interfaces : &new_smtp_port;
1358
1359 if (!*gp)
1360 {
1361 joinstr[0] = sep;
1362 joinstr[1] = ' ';
1363 *gp = string_catn(*gp, US"<", 1);
1364 }
1365
1366 *gp = string_catn(*gp, joinstr, 2);
1367 *gp = string_cat (*gp, s);
1368 }
1369
1370 if (new_smtp_port)
1371 {
1372 daemon_smtp_port = string_from_gstring(new_smtp_port);
1373 DEBUG(D_any) debug_printf("daemon_smtp_port overridden by -oX:\n %s\n",
1374 daemon_smtp_port);
1375 }
1376
1377 if (new_local_interfaces)
1378 {
1379 local_interfaces = string_from_gstring(new_local_interfaces);
1380 local_iface_source = US"-oX data";
1381 DEBUG(D_any) debug_printf("local_interfaces overridden by -oX:\n %s\n",
1382 local_interfaces);
1383 }
1384 }
1385
1386 /* Create a list of default SMTP ports, to be used if local_interfaces
1387 contains entries without explicit ports. First count the number of ports, then
1388 build a translated list in a vector. */
1389
1390 list = daemon_smtp_port;
1391 sep = 0;
1392 while ((s = string_nextinlist(&list, &sep, big_buffer, big_buffer_size)))
1393 pct++;
1394 default_smtp_port = store_get((pct+1) * sizeof(int), FALSE);
1395 list = daemon_smtp_port;
1396 sep = 0;
1397 for (pct = 0;
1398 (s = string_nextinlist(&list, &sep, big_buffer, big_buffer_size));
1399 pct++)
1400 {
1401 if (isdigit(*s))
1402 {
1403 uschar *end;
1404 default_smtp_port[pct] = Ustrtol(s, &end, 0);
1405 if (end != s + Ustrlen(s))
1406 log_write(0, LOG_PANIC_DIE|LOG_CONFIG, "invalid SMTP port: %s", s);
1407 }
1408 else
1409 {
1410 struct servent *smtp_service = getservbyname(CS s, "tcp");
1411 if (!smtp_service)
1412 log_write(0, LOG_PANIC_DIE|LOG_CONFIG, "TCP port \"%s\" not found", s);
1413 default_smtp_port[pct] = ntohs(smtp_service->s_port);
1414 }
1415 }
1416 default_smtp_port[pct] = 0;
1417
1418 /* Check the list of TLS-on-connect ports and do name lookups if needed */
1419
1420 list = tls_in.on_connect_ports;
1421 sep = 0;
1422 while ((s = string_nextinlist(&list, &sep, big_buffer, big_buffer_size)))
1423 if (!isdigit(*s))
1424 {
1425 gstring * g = NULL;
1426
1427 list = tls_in.on_connect_ports;
1428 tls_in.on_connect_ports = NULL;
1429 sep = 0;
1430 while ((s = string_nextinlist(&list, &sep, big_buffer, big_buffer_size)))
1431 {
1432 if (!isdigit(*s))
1433 {
1434 struct servent * smtp_service = getservbyname(CS s, "tcp");
1435 if (!smtp_service)
1436 log_write(0, LOG_PANIC_DIE|LOG_CONFIG, "TCP port \"%s\" not found", s);
1437 s = string_sprintf("%d", (int)ntohs(smtp_service->s_port));
1438 }
1439 g = string_append_listele(g, ':', s);
1440 }
1441 if (g)
1442 tls_in.on_connect_ports = g->s;
1443 break;
1444 }
1445
1446 /* Create the list of local interfaces, possibly with ports included. This
1447 list may contain references to 0.0.0.0 and ::0 as wildcards. These special
1448 values are converted below. */
1449
1450 addresses = host_build_ifacelist(local_interfaces, local_iface_source);
1451
1452 /* In the list of IP addresses, convert 0.0.0.0 into an empty string, and ::0
1453 into the string ":". We use these to recognize wildcards in IPv4 and IPv6. In
1454 fact, many IP stacks recognize 0.0.0.0 and ::0 and handle them as wildcards
1455 anyway, but we need to know which are the wildcard addresses, and the shorter
1456 strings are neater.
1457
1458 In the same scan, fill in missing port numbers from the default list. When
1459 there is more than one item in the list, extra items are created. */
1460
1461 for (ipa = addresses; ipa; ipa = ipa->next)
1462 {
1463 if (Ustrcmp(ipa->address, "0.0.0.0") == 0)
1464 ipa->address[0] = 0;
1465 else if (Ustrcmp(ipa->address, "::0") == 0)
1466 {
1467 ipa->address[0] = ':';
1468 ipa->address[1] = 0;
1469 }
1470
1471 if (ipa->port > 0) continue;
1472
1473 if (daemon_smtp_port[0] <= 0)
1474 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "no port specified for interface "
1475 "%s and daemon_smtp_port is unset; cannot start daemon",
1476 ipa->address[0] == 0 ? US"\"all IPv4\"" :
1477 ipa->address[1] == 0 ? US"\"all IPv6\"" : ipa->address);
1478
1479 ipa->port = default_smtp_port[0];
1480 for (int i = 1; default_smtp_port[i] > 0; i++)
1481 {
1482 ip_address_item *new = store_get(sizeof(ip_address_item), FALSE);
1483
1484 memcpy(new->address, ipa->address, Ustrlen(ipa->address) + 1);
1485 new->port = default_smtp_port[i];
1486 new->next = ipa->next;
1487 ipa->next = new;
1488 ipa = new;
1489 }
1490 }
1491
1492 /* Scan the list of addresses for wildcards. If we find an IPv4 and an IPv6
1493 wildcard for the same port, ensure that (a) they are together and (b) the
1494 IPv6 address comes first. This makes handling the messy features easier, and
1495 also simplifies the construction of the "daemon started" log line. */
1496
1497 pipa = &addresses;
1498 for (ipa = addresses; ipa; pipa = &ipa->next, ipa = ipa->next)
1499 {
1500 ip_address_item *ipa2;
1501
1502 /* Handle an IPv4 wildcard */
1503
1504 if (ipa->address[0] == 0)
1505 for (ipa2 = ipa; ipa2->next; ipa2 = ipa2->next)
1506 {
1507 ip_address_item *ipa3 = ipa2->next;
1508 if (ipa3->address[0] == ':' &&
1509 ipa3->address[1] == 0 &&
1510 ipa3->port == ipa->port)
1511 {
1512 ipa2->next = ipa3->next;
1513 ipa3->next = ipa;
1514 *pipa = ipa3;
1515 break;
1516 }
1517 }
1518
1519 /* Handle an IPv6 wildcard. */
1520
1521 else if (ipa->address[0] == ':' && ipa->address[1] == 0)
1522 for (ipa2 = ipa; ipa2->next; ipa2 = ipa2->next)
1523 {
1524 ip_address_item *ipa3 = ipa2->next;
1525 if (ipa3->address[0] == 0 && ipa3->port == ipa->port)
1526 {
1527 ipa2->next = ipa3->next;
1528 ipa3->next = ipa->next;
1529 ipa->next = ipa3;
1530 ipa = ipa3;
1531 break;
1532 }
1533 }
1534 }
1535
1536 /* Get a vector to remember all the sockets in */
1537
1538 for (ipa = addresses; ipa; ipa = ipa->next)
1539 listen_socket_count++;
1540 listen_sockets = store_get(sizeof(int) * listen_socket_count, FALSE);
1541
1542 } /* daemon_listen but not inetd_wait_mode */
1543
1544 if (f.daemon_listen)
1545 {
1546
1547 /* Do a sanity check on the max connects value just to save us from getting
1548 a huge amount of store. */
1549
1550 if (smtp_accept_max > 4095) smtp_accept_max = 4096;
1551
1552 /* There's no point setting smtp_accept_queue unless it is less than the max
1553 connects limit. The configuration reader ensures that the max is set if the
1554 queue-only option is set. */
1555
1556 if (smtp_accept_queue > smtp_accept_max) smtp_accept_queue = 0;
1557
1558 /* Get somewhere to keep the list of SMTP accepting pids if we are keeping
1559 track of them for total number and queue/host limits. */
1560
1561 if (smtp_accept_max > 0)
1562 {
1563 smtp_slots = store_get(smtp_accept_max * sizeof(smtp_slot), FALSE);
1564 for (int i = 0; i < smtp_accept_max; i++) smtp_slots[i] = empty_smtp_slot;
1565 }
1566 }
1567
1568 /* The variable background_daemon is always false when debugging, but
1569 can also be forced false in order to keep a non-debugging daemon in the
1570 foreground. If background_daemon is true, close all open file descriptors that
1571 we know about, but then re-open stdin, stdout, and stderr to /dev/null. Also
1572 do this for inetd_wait mode.
1573
1574 This is protection against any called functions (in libraries, or in
1575 Perl, or whatever) that think they can write to stderr (or stdout). Before this
1576 was added, it was quite likely that an SMTP connection would use one of these
1577 file descriptors, in which case writing random stuff to it caused chaos.
1578
1579 Then disconnect from the controlling terminal, Most modern Unixes seem to have
1580 setsid() for getting rid of the controlling terminal. For any OS that doesn't,
1581 setsid() can be #defined as a no-op, or as something else. */
1582
1583 if (f.background_daemon || f.inetd_wait_mode)
1584 {
1585 log_close_all(); /* Just in case anything was logged earlier */
1586 search_tidyup(); /* Just in case any were used in reading the config. */
1587 (void)close(0); /* Get rid of stdin/stdout/stderr */
1588 (void)close(1);
1589 (void)close(2);
1590 exim_nullstd(); /* Connect stdin/stdout/stderr to /dev/null */
1591 log_stderr = NULL; /* So no attempt to copy paniclog output */
1592 }
1593
1594 if (f.background_daemon)
1595 {
1596 /* If the parent process of this one has pid == 1, we are re-initializing the
1597 daemon as the result of a SIGHUP. In this case, there is no need to do
1598 anything, because the controlling terminal has long gone. Otherwise, fork, in
1599 case current process is a process group leader (see 'man setsid' for an
1600 explanation) before calling setsid(). */
1601
1602 if (getppid() != 1)
1603 {
1604 pid_t pid = fork();
1605 if (pid < 0) log_write(0, LOG_MAIN|LOG_PANIC_DIE,
1606 "fork() failed when starting daemon: %s", strerror(errno));
1607 if (pid > 0) exit(EXIT_SUCCESS); /* in parent process, just exit */
1608 (void)setsid(); /* release controlling terminal */
1609 }
1610 }
1611
1612 /* We are now in the disconnected, daemon process (unless debugging). Set up
1613 the listening sockets if required. */
1614
1615 daemon_notifier_socket();
1616
1617 if (f.daemon_listen && !f.inetd_wait_mode)
1618 {
1619 int sk;
1620 ip_address_item *ipa;
1621
1622 /* For each IP address, create a socket, bind it to the appropriate port, and
1623 start listening. See comments above about IPv6 sockets that may or may not
1624 accept IPv4 calls when listening on all interfaces. We also have to cope with
1625 the case of a system with IPv6 libraries, but no IPv6 support in the kernel.
1626 listening, provided a wildcard IPv4 socket for the same port follows. */
1627
1628 for (ipa = addresses, sk = 0; sk < listen_socket_count; ipa = ipa->next, sk++)
1629 {
1630 BOOL wildcard;
1631 ip_address_item *ipa2;
1632 int af;
1633
1634 if (Ustrchr(ipa->address, ':') != NULL)
1635 {
1636 af = AF_INET6;
1637 wildcard = ipa->address[1] == 0;
1638 }
1639 else
1640 {
1641 af = AF_INET;
1642 wildcard = ipa->address[0] == 0;
1643 }
1644
1645 if ((listen_sockets[sk] = ip_socket(SOCK_STREAM, af)) < 0)
1646 {
1647 if (check_special_case(0, addresses, ipa, FALSE))
1648 {
1649 log_write(0, LOG_MAIN, "Failed to create IPv6 socket for wildcard "
1650 "listening (%s): will use IPv4", strerror(errno));
1651 goto SKIP_SOCKET;
1652 }
1653 log_write(0, LOG_PANIC_DIE, "IPv%c socket creation failed: %s",
1654 (af == AF_INET6)? '6' : '4', strerror(errno));
1655 }
1656
1657 /* If this is an IPv6 wildcard socket, set IPV6_V6ONLY if that option is
1658 available. Just log failure (can get protocol not available, just like
1659 socket creation can). */
1660
1661 #ifdef IPV6_V6ONLY
1662 if (af == AF_INET6 && wildcard &&
1663 setsockopt(listen_sockets[sk], IPPROTO_IPV6, IPV6_V6ONLY, CS (&on),
1664 sizeof(on)) < 0)
1665 log_write(0, LOG_MAIN, "Setting IPV6_V6ONLY on daemon's IPv6 wildcard "
1666 "socket failed (%s): carrying on without it", strerror(errno));
1667 #endif /* IPV6_V6ONLY */
1668
1669 /* Set SO_REUSEADDR so that the daemon can be restarted while a connection
1670 is being handled. Without this, a connection will prevent reuse of the
1671 smtp port for listening. */
1672
1673 if (setsockopt(listen_sockets[sk], SOL_SOCKET, SO_REUSEADDR,
1674 US (&on), sizeof(on)) < 0)
1675 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "setting SO_REUSEADDR on socket "
1676 "failed when starting daemon: %s", strerror(errno));
1677
1678 /* Set TCP_NODELAY; Exim does its own buffering. There is a switch to
1679 disable this because it breaks some broken clients. */
1680
1681 if (tcp_nodelay) setsockopt(listen_sockets[sk], IPPROTO_TCP, TCP_NODELAY,
1682 US (&on), sizeof(on));
1683
1684 /* Now bind the socket to the required port; if Exim is being restarted
1685 it may not always be possible to bind immediately, even with SO_REUSEADDR
1686 set, so try 10 times, waiting between each try. After 10 failures, we give
1687 up. In an IPv6 environment, if bind () fails with the error EADDRINUSE and
1688 we are doing wildcard IPv4 listening and there was a previous IPv6 wildcard
1689 address for the same port, ignore the error on the grounds that we must be
1690 in a system where the IPv6 socket accepts both kinds of call. This is
1691 necessary for (some release of) USAGI Linux; other IP stacks fail at the
1692 listen() stage instead. */
1693
1694 #ifdef TCP_FASTOPEN
1695 f.tcp_fastopen_ok = TRUE;
1696 #endif
1697 for(;;)
1698 {
1699 uschar *msg, *addr;
1700 if (ip_bind(listen_sockets[sk], af, ipa->address, ipa->port) >= 0) break;
1701 if (check_special_case(errno, addresses, ipa, TRUE))
1702 {
1703 DEBUG(D_any) debug_printf("wildcard IPv4 bind() failed after IPv6 "
1704 "listen() success; EADDRINUSE ignored\n");
1705 (void)close(listen_sockets[sk]);
1706 goto SKIP_SOCKET;
1707 }
1708 msg = US strerror(errno);
1709 addr = wildcard
1710 ? af == AF_INET6
1711 ? US"(any IPv6)"
1712 : US"(any IPv4)"
1713 : ipa->address;
1714 if (daemon_startup_retries <= 0)
1715 log_write(0, LOG_MAIN|LOG_PANIC_DIE,
1716 "socket bind() to port %d for address %s failed: %s: "
1717 "daemon abandoned", ipa->port, addr, msg);
1718 log_write(0, LOG_MAIN, "socket bind() to port %d for address %s "
1719 "failed: %s: waiting %s before trying again (%d more %s)",
1720 ipa->port, addr, msg, readconf_printtime(daemon_startup_sleep),
1721 daemon_startup_retries, (daemon_startup_retries > 1)? "tries" : "try");
1722 daemon_startup_retries--;
1723 sleep(daemon_startup_sleep);
1724 }
1725
1726 DEBUG(D_any)
1727 if (wildcard)
1728 debug_printf("listening on all interfaces (IPv%c) port %d\n",
1729 af == AF_INET6 ? '6' : '4', ipa->port);
1730 else
1731 debug_printf("listening on %s port %d\n", ipa->address, ipa->port);
1732
1733 #if defined(TCP_FASTOPEN) && !defined(__APPLE__)
1734 if ( f.tcp_fastopen_ok
1735 && setsockopt(listen_sockets[sk], IPPROTO_TCP, TCP_FASTOPEN,
1736 &smtp_connect_backlog, sizeof(smtp_connect_backlog)))
1737 {
1738 DEBUG(D_any) debug_printf("setsockopt FASTOPEN: %s\n", strerror(errno));
1739 f.tcp_fastopen_ok = FALSE;
1740 }
1741 #endif
1742
1743 /* Start listening on the bound socket, establishing the maximum backlog of
1744 connections that is allowed. On success, continue to the next address. */
1745
1746 if (listen(listen_sockets[sk], smtp_connect_backlog) >= 0)
1747 {
1748 #if defined(TCP_FASTOPEN) && defined(__APPLE__)
1749 if ( f.tcp_fastopen_ok
1750 && setsockopt(listen_sockets[sk], IPPROTO_TCP, TCP_FASTOPEN,
1751 &on, sizeof(on)))
1752 {
1753 DEBUG(D_any) debug_printf("setsockopt FASTOPEN: %s\n", strerror(errno));
1754 f.tcp_fastopen_ok = FALSE;
1755 }
1756 #endif
1757 continue;
1758 }
1759
1760 /* Listening has failed. In an IPv6 environment, as for bind(), if listen()
1761 fails with the error EADDRINUSE and we are doing IPv4 wildcard listening
1762 and there was a previous successful IPv6 wildcard listen on the same port,
1763 we want to ignore the error on the grounds that we must be in a system
1764 where the IPv6 socket accepts both kinds of call. */
1765
1766 if (!check_special_case(errno, addresses, ipa, TRUE))
1767 log_write(0, LOG_PANIC_DIE, "listen() failed on interface %s: %s",
1768 wildcard
1769 ? af == AF_INET6 ? US"(any IPv6)" : US"(any IPv4)" : ipa->address,
1770 strerror(errno));
1771
1772 DEBUG(D_any) debug_printf("wildcard IPv4 listen() failed after IPv6 "
1773 "listen() success; EADDRINUSE ignored\n");
1774 (void)close(listen_sockets[sk]);
1775
1776 /* Come here if there has been a problem with the socket which we
1777 are going to ignore. We remove the address from the chain, and back up the
1778 counts. */
1779
1780 SKIP_SOCKET:
1781 sk--; /* Back up the count */
1782 listen_socket_count--; /* Reduce the total */
1783 if (ipa == addresses) addresses = ipa->next; else
1784 {
1785 for (ipa2 = addresses; ipa2->next != ipa; ipa2 = ipa2->next);
1786 ipa2->next = ipa->next;
1787 ipa = ipa2;
1788 }
1789 } /* End of bind/listen loop for each address */
1790 } /* End of setup for listening */
1791
1792
1793 /* If we are not listening, we want to write a pid file only if -oP was
1794 explicitly given. */
1795
1796 else if (!override_pid_file_path)
1797 write_pid = FALSE;
1798
1799 /* Write the pid to a known file for assistance in identification, if required.
1800 We do this before giving up root privilege, because on some systems it is
1801 necessary to be root in order to write into the pid file directory. There's
1802 nothing to stop multiple daemons running, as long as no more than one listens
1803 on a given TCP/IP port on the same interface(s). However, in these
1804 circumstances it gets far too complicated to mess with pid file names
1805 automatically. Consequently, Exim 4 writes a pid file only
1806
1807 (a) When running in the test harness, or
1808 (b) When -bd is used and -oX is not used, or
1809 (c) When -oP is used to supply a path.
1810
1811 The variable daemon_write_pid is used to control this. */
1812
1813 if (f.running_in_test_harness || write_pid)
1814 {
1815 FILE *f;
1816
1817 set_pid_file_path();
1818 if ((f = modefopen(pid_file_path, "wb", 0644)))
1819 {
1820 (void)fprintf(f, "%d\n", (int)getpid());
1821 (void)fclose(f);
1822 DEBUG(D_any) debug_printf("pid written to %s\n", pid_file_path);
1823 }
1824 else
1825 DEBUG(D_any)
1826 debug_printf("%s\n", string_open_failed(errno, "pid file %s",
1827 pid_file_path));
1828 }
1829
1830 /* Set up the handler for SIGHUP, which causes a restart of the daemon. */
1831
1832 sighup_seen = FALSE;
1833 signal(SIGHUP, sighup_handler);
1834
1835 /* Give up root privilege at this point (assuming that exim_uid and exim_gid
1836 are not root). The third argument controls the running of initgroups().
1837 Normally we do this, in order to set up the groups for the Exim user. However,
1838 if we are not root at this time - some odd installations run that way - we
1839 cannot do this. */
1840
1841 exim_setugid(exim_uid, exim_gid, geteuid()==root_uid, US"running as a daemon");
1842
1843 /* Update the originator_xxx fields so that received messages as listed as
1844 coming from Exim, not whoever started the daemon. */
1845
1846 originator_uid = exim_uid;
1847 originator_gid = exim_gid;
1848 originator_login = (pw = getpwuid(exim_uid))
1849 ? string_copy_perm(US pw->pw_name, FALSE) : US"exim";
1850
1851 /* Get somewhere to keep the list of queue-runner pids if we are keeping track
1852 of them (and also if we are doing queue runs). */
1853
1854 if (queue_interval > 0 && local_queue_run_max > 0)
1855 {
1856 queue_pid_slots = store_get(local_queue_run_max * sizeof(pid_t), FALSE);
1857 for (int i = 0; i < local_queue_run_max; i++) queue_pid_slots[i] = 0;
1858 }
1859
1860 /* Set up the handler for termination of child processes, and the one
1861 telling us to die. */
1862
1863 sigchld_seen = FALSE;
1864 os_non_restarting_signal(SIGCHLD, main_sigchld_handler);
1865
1866 sigterm_seen = FALSE;
1867 os_non_restarting_signal(SIGTERM, main_sigterm_handler);
1868
1869 /* If we are to run the queue periodically, pretend the alarm has just gone
1870 off. This will cause the first queue-runner to get kicked off straight away. */
1871
1872 sigalrm_seen = (queue_interval > 0);
1873
1874 /* Log the start up of a daemon - at least one of listening or queue running
1875 must be set up. */
1876
1877 if (f.inetd_wait_mode)
1878 {
1879 uschar *p = big_buffer;
1880
1881 if (inetd_wait_timeout >= 0)
1882 sprintf(CS p, "terminating after %d seconds", inetd_wait_timeout);
1883 else
1884 sprintf(CS p, "with no wait timeout");
1885
1886 log_write(0, LOG_MAIN,
1887 "exim %s daemon started: pid=%d, launched with listening socket, %s",
1888 version_string, getpid(), big_buffer);
1889 set_process_info("daemon(%s): pre-listening socket", version_string);
1890
1891 /* set up the timeout logic */
1892 sigalrm_seen = TRUE;
1893 }
1894
1895 else if (f.daemon_listen)
1896 {
1897 int smtp_ports = 0;
1898 int smtps_ports = 0;
1899 ip_address_item * ipa;
1900 uschar * p;
1901 uschar * qinfo = queue_interval > 0
1902 ? string_sprintf("-q%s", readconf_printtime(queue_interval))
1903 : US"no queue runs";
1904
1905 /* Build a list of listening addresses in big_buffer, but limit it to 10
1906 items. The style is for backwards compatibility.
1907
1908 It is now possible to have some ports listening for SMTPS (the old,
1909 deprecated protocol that starts TLS without using STARTTLS), and others
1910 listening for standard SMTP. Keep their listings separate. */
1911
1912 for (int j = 0, i; j < 2; j++)
1913 {
1914 for (i = 0, ipa = addresses; i < 10 && ipa; i++, ipa = ipa->next)
1915 {
1916 /* First time round, look for SMTP ports; second time round, look for
1917 SMTPS ports. Build IP+port strings. */
1918
1919 if (host_is_tls_on_connect_port(ipa->port) == (j > 0))
1920 {
1921 if (j == 0)
1922 smtp_ports++;
1923 else
1924 smtps_ports++;
1925
1926 /* Now the information about the port (and sometimes interface) */
1927
1928 if (ipa->address[0] == ':' && ipa->address[1] == 0)
1929 { /* v6 wildcard */
1930 if (ipa->next && ipa->next->address[0] == 0 &&
1931 ipa->next->port == ipa->port)
1932 {
1933 ipa->log = string_sprintf(" port %d (IPv6 and IPv4)", ipa->port);
1934 (ipa = ipa->next)->log = NULL;
1935 }
1936 else if (ipa->v6_include_v4)
1937 ipa->log = string_sprintf(" port %d (IPv6 with IPv4)", ipa->port);
1938 else
1939 ipa->log = string_sprintf(" port %d (IPv6)", ipa->port);
1940 }
1941 else if (ipa->address[0] == 0) /* v4 wildcard */
1942 ipa->log = string_sprintf(" port %d (IPv4)", ipa->port);
1943 else /* check for previously-seen IP */
1944 {
1945 ip_address_item * i2;
1946 for (i2 = addresses; i2 != ipa; i2 = i2->next)
1947 if ( host_is_tls_on_connect_port(i2->port) == (j > 0)
1948 && Ustrcmp(ipa->address, i2->address) == 0
1949 )
1950 { /* found; append port to list */
1951 for (p = i2->log; *p; ) p++; /* end of existing string */
1952 if (*--p == '}') *p = '\0'; /* drop EOL */
1953 while (isdigit(*--p)) ; /* char before port */
1954
1955 i2->log = *p == ':' /* no list yet? */
1956 ? string_sprintf("%.*s{%s,%d}",
1957 (int)(p - i2->log + 1), i2->log, p+1, ipa->port)
1958 : string_sprintf("%s,%d}", i2->log, ipa->port);
1959 ipa->log = NULL;
1960 break;
1961 }
1962 if (i2 == ipa) /* first-time IP */
1963 ipa->log = string_sprintf(" [%s]:%d", ipa->address, ipa->port);
1964 }
1965 }
1966 }
1967 }
1968
1969 p = big_buffer;
1970 for (int j = 0, i; j < 2; j++)
1971 {
1972 /* First time round, look for SMTP ports; second time round, look for
1973 SMTPS ports. For the first one of each, insert leading text. */
1974
1975 if (j == 0)
1976 {
1977 if (smtp_ports > 0)
1978 p += sprintf(CS p, "SMTP on");
1979 }
1980 else
1981 if (smtps_ports > 0)
1982 p += sprintf(CS p, "%sSMTPS on",
1983 smtp_ports == 0 ? "" : " and for ");
1984
1985 /* Now the information about the port (and sometimes interface) */
1986
1987 for (i = 0, ipa = addresses; i < 10 && ipa; i++, ipa = ipa->next)
1988 if (host_is_tls_on_connect_port(ipa->port) == (j > 0))
1989 if (ipa->log)
1990 p += sprintf(CS p, "%s", ipa->log);
1991
1992 if (ipa)
1993 p += sprintf(CS p, " ...");
1994 }
1995
1996 log_write(0, LOG_MAIN,
1997 "exim %s daemon started: pid=%d, %s, listening for %s",
1998 version_string, getpid(), qinfo, big_buffer);
1999 set_process_info("daemon(%s): %s, listening for %s",
2000 version_string, qinfo, big_buffer);
2001 }
2002
2003 else
2004 {
2005 uschar * s = *queue_name
2006 ? string_sprintf("-qG%s/%s", queue_name, readconf_printtime(queue_interval))
2007 : string_sprintf("-q%s", readconf_printtime(queue_interval));
2008 log_write(0, LOG_MAIN,
2009 "exim %s daemon started: pid=%d, %s, not listening for SMTP",
2010 version_string, getpid(), s);
2011 set_process_info("daemon(%s): %s, not listening", version_string, s);
2012 }
2013
2014 /* Do any work it might be useful to amortize over our children
2015 (eg: compile regex) */
2016
2017 dns_pattern_init();
2018 smtp_deliver_init(); /* Used for callouts */
2019
2020 #ifndef DISABLE_DKIM
2021 {
2022 # ifdef MEASURE_TIMING
2023 struct timeval t0;
2024 gettimeofday(&t0, NULL);
2025 # endif
2026 dkim_exim_init();
2027 # ifdef MEASURE_TIMING
2028 report_time_since(&t0, US"dkim_exim_init (delta)");
2029 # endif
2030 }
2031 #endif
2032
2033 #ifdef WITH_CONTENT_SCAN
2034 malware_init();
2035 #endif
2036 #ifdef SUPPORT_SPF
2037 spf_init();
2038 #endif
2039
2040 /* Close the log so it can be renamed and moved. In the few cases below where
2041 this long-running process writes to the log (always exceptional conditions), it
2042 closes the log afterwards, for the same reason. */
2043
2044 log_close_all();
2045
2046 DEBUG(D_any) debug_print_ids(US"daemon running with");
2047
2048 /* Any messages accepted via this route are going to be SMTP. */
2049
2050 smtp_input = TRUE;
2051
2052 #ifdef MEASURE_TIMING
2053 report_time_since(&timestamp_startup, US"daemon loop start"); /* testcase 0022 */
2054 #endif
2055
2056 /* Enter the never-ending loop... */
2057
2058 for (;;)
2059 {
2060 #if HAVE_IPV6
2061 struct sockaddr_in6 accepted;
2062 #else
2063 struct sockaddr_in accepted;
2064 #endif
2065
2066 EXIM_SOCKLEN_T len;
2067 pid_t pid;
2068
2069 if (sigterm_seen)
2070 daemon_die(); /* Does not return */
2071
2072 /* This code is placed first in the loop, so that it gets obeyed at the
2073 start, before the first wait, for the queue-runner case, so that the first
2074 one can be started immediately.
2075
2076 The other option is that we have an inetd wait timeout specified to -bw. */
2077
2078 if (sigalrm_seen)
2079 {
2080 if (inetd_wait_timeout > 0)
2081 {
2082 time_t resignal_interval = inetd_wait_timeout;
2083
2084 if (last_connection_time == (time_t)0)
2085 {
2086 DEBUG(D_any)
2087 debug_printf("inetd wait timeout expired, but still not seen first message, ignoring\n");
2088 }
2089 else
2090 {
2091 time_t now = time(NULL);
2092 if (now == (time_t)-1)
2093 {
2094 DEBUG(D_any) debug_printf("failed to get time: %s\n", strerror(errno));
2095 }
2096 else
2097 {
2098 if ((now - last_connection_time) >= inetd_wait_timeout)
2099 {
2100 DEBUG(D_any)
2101 debug_printf("inetd wait timeout %d expired, ending daemon\n",
2102 inetd_wait_timeout);
2103 log_write(0, LOG_MAIN, "exim %s daemon terminating, inetd wait timeout reached.\n",
2104 version_string);
2105 exit(EXIT_SUCCESS);
2106 }
2107 else
2108 {
2109 resignal_interval -= (now - last_connection_time);
2110 }
2111 }
2112 }
2113
2114 sigalrm_seen = FALSE;
2115 ALARM(resignal_interval);
2116 }
2117
2118 else
2119 {
2120 DEBUG(D_any) debug_printf("%s received\n",
2121 #ifdef EXPERIMENTAL_QUEUE_RAMP
2122 *queuerun_msgid ? "qrun notification" :
2123 #endif
2124 "SIGALRM");
2125
2126 /* Do a full queue run in a child process, if required, unless we already
2127 have enough queue runners on the go. If we are not running as root, a
2128 re-exec is required. */
2129
2130 if (queue_interval > 0 &&
2131 (local_queue_run_max <= 0 || queue_run_count < local_queue_run_max))
2132 {
2133 if ((pid = fork()) == 0)
2134 {
2135 DEBUG(D_any) debug_printf("Starting queue-runner: pid %d\n",
2136 (int)getpid());
2137
2138 /* Disable debugging if it's required only for the daemon process. We
2139 leave the above message, because it ties up with the "child ended"
2140 debugging messages. */
2141
2142 if (f.debug_daemon) debug_selector = 0;
2143
2144 /* Close any open listening sockets in the child */
2145
2146 close_daemon_sockets(daemon_notifier_fd,
2147 listen_sockets, listen_socket_count);
2148
2149 /* Reset SIGHUP and SIGCHLD in the child in both cases. */
2150
2151 signal(SIGHUP, SIG_DFL);
2152 signal(SIGCHLD, SIG_DFL);
2153 signal(SIGTERM, SIG_DFL);
2154
2155 /* Re-exec if privilege has been given up, unless deliver_drop_
2156 privilege is set. Reset SIGALRM before exec(). */
2157
2158 if (geteuid() != root_uid && !deliver_drop_privilege)
2159 {
2160 uschar opt[8];
2161 uschar *p = opt;
2162 uschar *extra[7];
2163 int extracount = 1;
2164
2165 signal(SIGALRM, SIG_DFL);
2166 *p++ = '-';
2167 *p++ = 'q';
2168 if ( f.queue_2stage
2169 #ifdef EXPERIMENTAL_QUEUE_RAMP
2170 && !*queuerun_msgid
2171 #endif
2172 ) *p++ = 'q';
2173 if (f.queue_run_first_delivery) *p++ = 'i';
2174 if (f.queue_run_force) *p++ = 'f';
2175 if (f.deliver_force_thaw) *p++ = 'f';
2176 if (f.queue_run_local) *p++ = 'l';
2177 *p = 0;
2178 extra[0] = *queue_name
2179 ? string_sprintf("%sG%s", opt, queue_name) : opt;
2180
2181 #ifdef EXPERIMENTAL_QUEUE_RAMP
2182 if (*queuerun_msgid)
2183 {
2184 extra[extracount++] = queuerun_msgid; /* Trigger only the */
2185 extra[extracount++] = queuerun_msgid; /* one message */
2186 }
2187 #endif
2188
2189 /* If -R or -S were on the original command line, ensure they get
2190 passed on. */
2191
2192 if (deliver_selectstring)
2193 {
2194 extra[extracount++] = f.deliver_selectstring_regex ? US"-Rr" : US"-R";
2195 extra[extracount++] = deliver_selectstring;
2196 }
2197
2198 if (deliver_selectstring_sender)
2199 {
2200 extra[extracount++] = f.deliver_selectstring_sender_regex
2201 ? US"-Sr" : US"-S";
2202 extra[extracount++] = deliver_selectstring_sender;
2203 }
2204
2205 /* Overlay this process with a new execution. */
2206
2207 (void)child_exec_exim(CEE_EXEC_PANIC, FALSE, NULL, FALSE, extracount,
2208 extra[0], extra[1], extra[2], extra[3], extra[4], extra[5], extra[6]);
2209
2210 /* Control never returns here. */
2211 }
2212
2213 /* No need to re-exec; SIGALRM remains set to the default handler */
2214
2215 #ifdef EXPERIMENTAL_QUEUE_RAMP
2216 if (*queuerun_msgid)
2217 {
2218 f.queue_2stage = FALSE;
2219 queue_run(queuerun_msgid, queuerun_msgid, FALSE);
2220 }
2221 else
2222 #endif
2223 queue_run(NULL, NULL, FALSE);
2224 exim_underbar_exit(EXIT_SUCCESS, US"queue-runner");
2225 }
2226
2227 if (pid < 0)
2228 {
2229 log_write(0, LOG_MAIN|LOG_PANIC, "daemon: fork of queue-runner "
2230 "process failed: %s", strerror(errno));
2231 log_close_all();
2232 }
2233 else
2234 {
2235 for (int i = 0; i < local_queue_run_max; ++i)
2236 if (queue_pid_slots[i] <= 0)
2237 {
2238 queue_pid_slots[i] = pid;
2239 queue_run_count++;
2240 break;
2241 }
2242 DEBUG(D_any) debug_printf("%d queue-runner process%s running\n",
2243 queue_run_count, queue_run_count == 1 ? "" : "es");
2244 }
2245 }
2246
2247 /* Reset the alarm clock */
2248
2249 sigalrm_seen = FALSE;
2250 #ifdef EXPERIMENTAL_QUEUE_RAMP
2251 if (*queuerun_msgid)
2252 *queuerun_msgid = 0;
2253 else
2254 #endif
2255 ALARM(queue_interval);
2256 }
2257
2258 } /* sigalrm_seen */
2259
2260
2261 /* Sleep till a connection happens if listening, and handle the connection if
2262 that is why we woke up. The FreeBSD operating system requires the use of
2263 select() before accept() because the latter function is not interrupted by
2264 a signal, and we want to wake up for SIGCHLD and SIGALRM signals. Some other
2265 OS do notice signals in accept() but it does no harm to have the select()
2266 in for all of them - and it won't then be a lurking problem for ports to
2267 new OS. In fact, the later addition of listening on specific interfaces only
2268 requires this way of working anyway. */
2269
2270 if (f.daemon_listen)
2271 {
2272 int lcount, select_errno;
2273 int max_socket = 0;
2274 BOOL select_failed = FALSE;
2275 fd_set select_listen;
2276
2277 FD_ZERO(&select_listen);
2278 if (daemon_notifier_fd >= 0)
2279 FD_SET(daemon_notifier_fd, &select_listen);
2280 for (int sk = 0; sk < listen_socket_count; sk++)
2281 {
2282 FD_SET(listen_sockets[sk], &select_listen);
2283 if (listen_sockets[sk] > max_socket) max_socket = listen_sockets[sk];
2284 }
2285
2286 DEBUG(D_any) debug_printf("Listening...\n");
2287
2288 /* In rare cases we may have had a SIGCHLD signal in the time between
2289 setting the handler (below) and getting back here. If so, pretend that the
2290 select() was interrupted so that we reap the child. This might still leave
2291 a small window when a SIGCHLD could get lost. However, since we use SIGCHLD
2292 only to do the reaping more quickly, it shouldn't result in anything other
2293 than a delay until something else causes a wake-up. */
2294
2295 if (sigchld_seen)
2296 {
2297 lcount = -1;
2298 errno = EINTR;
2299 }
2300 else
2301 lcount = select(max_socket + 1, (SELECT_ARG2_TYPE *)&select_listen,
2302 NULL, NULL, NULL);
2303
2304 if (lcount < 0)
2305 {
2306 select_failed = TRUE;
2307 lcount = 1;
2308 }
2309
2310 /* Clean up any subprocesses that may have terminated. We need to do this
2311 here so that smtp_accept_max_per_host works when a connection to that host
2312 has completed, and we are about to accept a new one. When this code was
2313 later in the sequence, a new connection could be rejected, even though an
2314 old one had just finished. Preserve the errno from any select() failure for
2315 the use of the common select/accept error processing below. */
2316
2317 select_errno = errno;
2318 handle_ending_processes();
2319 errno = select_errno;
2320
2321 #ifndef DISABLE_TLS
2322 /* Create or rotate any required keys */
2323 tls_daemon_init();
2324 #endif
2325
2326 /* Loop for all the sockets that are currently ready to go. If select
2327 actually failed, we have set the count to 1 and select_failed=TRUE, so as
2328 to use the common error code for select/accept below. */
2329
2330 while (lcount-- > 0)
2331 {
2332 int accept_socket = -1;
2333
2334 if (!select_failed)
2335 {
2336 if ( daemon_notifier_fd >= 0
2337 && FD_ISSET(daemon_notifier_fd, &select_listen))
2338 {
2339 FD_CLR(daemon_notifier_fd, &select_listen);
2340 sigalrm_seen = daemon_notification();
2341 break; /* to top of daemon loop */
2342 }
2343 for (int sk = 0; sk < listen_socket_count; sk++)
2344 if (FD_ISSET(listen_sockets[sk], &select_listen))
2345 {
2346 len = sizeof(accepted);
2347 accept_socket = accept(listen_sockets[sk],
2348 (struct sockaddr *)&accepted, &len);
2349 FD_CLR(listen_sockets[sk], &select_listen);
2350 break;
2351 }
2352 }
2353
2354 /* If select or accept has failed and this was not caused by an
2355 interruption, log the incident and try again. With asymmetric TCP/IP
2356 routing errors such as "No route to network" have been seen here. Also
2357 "connection reset by peer" has been seen. These cannot be classed as
2358 disastrous errors, but they could fill up a lot of log. The code in smail
2359 crashes the daemon after 10 successive failures of accept, on the grounds
2360 that some OS fail continuously. Exim originally followed suit, but this
2361 appears to have caused problems. Now it just keeps going, but instead of
2362 logging each error, it batches them up when they are continuous. */
2363
2364 if (accept_socket < 0 && errno != EINTR)
2365 {
2366 if (accept_retry_count == 0)
2367 {
2368 accept_retry_errno = errno;
2369 accept_retry_select_failed = select_failed;
2370 }
2371 else
2372 {
2373 if (errno != accept_retry_errno ||
2374 select_failed != accept_retry_select_failed ||
2375 accept_retry_count >= 50)
2376 {
2377 log_write(0, LOG_MAIN | ((accept_retry_count >= 50)? LOG_PANIC : 0),
2378 "%d %s() failure%s: %s",
2379 accept_retry_count,
2380 accept_retry_select_failed? "select" : "accept",
2381 (accept_retry_count == 1)? "" : "s",
2382 strerror(accept_retry_errno));
2383 log_close_all();
2384 accept_retry_count = 0;
2385 accept_retry_errno = errno;
2386 accept_retry_select_failed = select_failed;
2387 }
2388 }
2389 accept_retry_count++;
2390 }
2391
2392 else
2393 {
2394 if (accept_retry_count > 0)
2395 {
2396 log_write(0, LOG_MAIN, "%d %s() failure%s: %s",
2397 accept_retry_count,
2398 accept_retry_select_failed? "select" : "accept",
2399 (accept_retry_count == 1)? "" : "s",
2400 strerror(accept_retry_errno));
2401 log_close_all();
2402 accept_retry_count = 0;
2403 }
2404 }
2405
2406 /* If select/accept succeeded, deal with the connection. */
2407
2408 if (accept_socket >= 0)
2409 {
2410 if (inetd_wait_timeout)
2411 last_connection_time = time(NULL);
2412 handle_smtp_call(listen_sockets, listen_socket_count, accept_socket,
2413 (struct sockaddr *)&accepted);
2414 }
2415 }
2416 }
2417
2418 /* If not listening, then just sleep for the queue interval. If we woke
2419 up early the last time for some other signal, it won't matter because
2420 the alarm signal will wake at the right time. This code originally used
2421 sleep() but it turns out that on the FreeBSD system, sleep() is not inter-
2422 rupted by signals, so it wasn't waking up for SIGALRM or SIGCHLD. Luckily
2423 select() can be used as an interruptible sleep() on all versions of Unix. */
2424
2425 else
2426 {
2427 struct timeval tv;
2428 tv.tv_sec = queue_interval;
2429 tv.tv_usec = 0;
2430 select(0, NULL, NULL, NULL, &tv);
2431 handle_ending_processes();
2432 }
2433
2434 /* Re-enable the SIGCHLD handler if it has been run. It can't do it
2435 for itself, because it isn't doing the waiting itself. */
2436
2437 if (sigchld_seen)
2438 {
2439 sigchld_seen = FALSE;
2440 os_non_restarting_signal(SIGCHLD, main_sigchld_handler);
2441 }
2442
2443 /* Handle being woken by SIGHUP. We know at this point that the result
2444 of accept() has been dealt with, so we can re-exec exim safely, first
2445 closing the listening sockets so that they can be reused. Cancel any pending
2446 alarm in case it is just about to go off, and set SIGHUP to be ignored so
2447 that another HUP in quick succession doesn't clobber the new daemon before it
2448 gets going. All log files get closed by the close-on-exec flag; however, if
2449 the exec fails, we need to close the logs. */
2450
2451 if (sighup_seen)
2452 {
2453 log_write(0, LOG_MAIN, "pid %d: SIGHUP received: re-exec daemon",
2454 getpid());
2455 close_daemon_sockets(daemon_notifier_fd,
2456 listen_sockets, listen_socket_count);
2457 ALARM_CLR(0);
2458 signal(SIGHUP, SIG_IGN);
2459 sighup_argv[0] = exim_path;
2460 exim_nullstd();
2461 execv(CS exim_path, (char *const *)sighup_argv);
2462 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "pid %d: exec of %s failed: %s",
2463 getpid(), exim_path, strerror(errno));
2464 log_close_all();
2465 }
2466
2467 } /* End of main loop */
2468
2469 /* Control never reaches here */
2470 }
2471
2472 /* vi: aw ai sw=2
2473 */
2474 /* End of exim_daemon.c */