66787896b01f52476a4034b04cecce2e8d26b6a4
[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
35 static int accept_retry_count = 0;
36 static int accept_retry_errno;
37 static BOOL accept_retry_select_failed;
38
39 static int queue_run_count = 0;
40 static pid_t *queue_pid_slots = NULL;
41 static smtp_slot *smtp_slots = NULL;
42
43 static BOOL write_pid = TRUE;
44
45
46
47 /*************************************************
48 * SIGHUP Handler *
49 *************************************************/
50
51 /* All this handler does is to set a flag and re-enable the signal.
52
53 Argument: the signal number
54 Returns: nothing
55 */
56
57 static void
58 sighup_handler(int sig)
59 {
60 sig = sig; /* Keep picky compilers happy */
61 sighup_seen = TRUE;
62 signal(SIGHUP, sighup_handler);
63 }
64
65
66
67 /*************************************************
68 * SIGCHLD handler for main daemon process *
69 *************************************************/
70
71 /* Don't re-enable the handler here, since we aren't doing the
72 waiting here. If the signal is re-enabled, there will just be an
73 infinite sequence of calls to this handler. The SIGCHLD signal is
74 used just as a means of waking up the daemon so that it notices
75 terminated subprocesses as soon as possible.
76
77 Argument: the signal number
78 Returns: nothing
79 */
80
81 static void
82 main_sigchld_handler(int sig)
83 {
84 sig = sig; /* Keep picky compilers happy */
85 os_non_restarting_signal(SIGCHLD, SIG_DFL);
86 sigchld_seen = TRUE;
87 }
88
89
90
91
92 /*************************************************
93 * Unexpected errors in SMTP calls *
94 *************************************************/
95
96 /* This function just saves a bit of repetitious coding.
97
98 Arguments:
99 log_msg Text of message to be logged
100 smtp_msg Text of SMTP error message
101 was_errno The failing errno
102
103 Returns: nothing
104 */
105
106 static void
107 never_error(uschar *log_msg, uschar *smtp_msg, int was_errno)
108 {
109 uschar *emsg = (was_errno <= 0)? US"" :
110 string_sprintf(": %s", strerror(was_errno));
111 log_write(0, LOG_MAIN|LOG_PANIC, "%s%s", log_msg, emsg);
112 if (smtp_out != NULL) smtp_printf("421 %s\r\n", FALSE, smtp_msg);
113 }
114
115
116
117
118 /*************************************************
119 * Handle a connected SMTP call *
120 *************************************************/
121
122 /* This function is called when an SMTP connection has been accepted.
123 If there are too many, give an error message and close down. Otherwise
124 spin off a sub-process to handle the call. The list of listening sockets
125 is required so that they can be closed in the sub-process. Take care not to
126 leak store in this process - reset the stacking pool at the end.
127
128 Arguments:
129 listen_sockets sockets which are listening for incoming calls
130 listen_socket_count count of listening sockets
131 accept_socket socket of the current accepted call
132 accepted socket information about the current call
133
134 Returns: nothing
135 */
136
137 static void
138 handle_smtp_call(int *listen_sockets, int listen_socket_count,
139 int accept_socket, struct sockaddr *accepted)
140 {
141 pid_t pid;
142 union sockaddr_46 interface_sockaddr;
143 EXIM_SOCKLEN_T ifsize = sizeof(interface_sockaddr);
144 int dup_accept_socket = -1;
145 int max_for_this_host = 0;
146 int save_log_selector = *log_selector;
147 gstring * whofrom;
148
149 void *reset_point = store_get(0);
150
151 /* Make the address available in ASCII representation, and also fish out
152 the remote port. */
153
154 sender_host_address = host_ntoa(-1, accepted, NULL, &sender_host_port);
155 DEBUG(D_any) debug_printf("Connection request from %s port %d\n",
156 sender_host_address, sender_host_port);
157
158 /* Set up the output stream, check the socket has duplicated, and set up the
159 input stream. These operations fail only the exceptional circumstances. Note
160 that never_error() won't use smtp_out if it is NULL. */
161
162 if (!(smtp_out = fdopen(accept_socket, "wb")))
163 {
164 never_error(US"daemon: fdopen() for smtp_out failed", US"", errno);
165 goto ERROR_RETURN;
166 }
167
168 if ((dup_accept_socket = dup(accept_socket)) < 0)
169 {
170 never_error(US"daemon: couldn't dup socket descriptor",
171 US"Connection setup failed", errno);
172 goto ERROR_RETURN;
173 }
174
175 if (!(smtp_in = fdopen(dup_accept_socket, "rb")))
176 {
177 never_error(US"daemon: fdopen() for smtp_in failed",
178 US"Connection setup failed", errno);
179 goto ERROR_RETURN;
180 }
181
182 /* Get the data for the local interface address. Panic for most errors, but
183 "connection reset by peer" just means the connection went away. */
184
185 if (getsockname(accept_socket, (struct sockaddr *)(&interface_sockaddr),
186 &ifsize) < 0)
187 {
188 log_write(0, LOG_MAIN | ((errno == ECONNRESET)? 0 : LOG_PANIC),
189 "getsockname() failed: %s", strerror(errno));
190 smtp_printf("421 Local problem: getsockname() failed; please try again later\r\n", FALSE);
191 goto ERROR_RETURN;
192 }
193
194 interface_address = host_ntoa(-1, &interface_sockaddr, NULL, &interface_port);
195 DEBUG(D_interface) debug_printf("interface address=%s port=%d\n",
196 interface_address, interface_port);
197
198 /* Build a string identifying the remote host and, if requested, the port and
199 the local interface data. This is for logging; at the end of this function the
200 memory is reclaimed. */
201
202 whofrom = string_append(NULL, 3, "[", sender_host_address, "]");
203
204 if (LOGGING(incoming_port))
205 whofrom = string_append(whofrom, 2, ":", string_sprintf("%d", sender_host_port));
206
207 if (LOGGING(incoming_interface))
208 whofrom = string_append(whofrom, 4, " I=[",
209 interface_address, "]:", string_sprintf("%d", interface_port));
210
211 (void) string_from_gstring(whofrom); /* Terminate the newly-built string */
212
213 /* Check maximum number of connections. We do not check for reserved
214 connections or unacceptable hosts here. That is done in the subprocess because
215 it might take some time. */
216
217 if (smtp_accept_max > 0 && smtp_accept_count >= smtp_accept_max)
218 {
219 DEBUG(D_any) debug_printf("rejecting SMTP connection: count=%d max=%d\n",
220 smtp_accept_count, smtp_accept_max);
221 smtp_printf("421 Too many concurrent SMTP connections; "
222 "please try again later.\r\n", FALSE);
223 log_write(L_connection_reject,
224 LOG_MAIN, "Connection from %s refused: too many connections",
225 whofrom->s);
226 goto ERROR_RETURN;
227 }
228
229 /* If a load limit above which only reserved hosts are acceptable is defined,
230 get the load average here, and if there are in fact no reserved hosts, do
231 the test right away (saves a fork). If there are hosts, do the check in the
232 subprocess because it might take time. */
233
234 if (smtp_load_reserve >= 0)
235 {
236 load_average = OS_GETLOADAVG();
237 if (smtp_reserve_hosts == NULL && load_average > smtp_load_reserve)
238 {
239 DEBUG(D_any) debug_printf("rejecting SMTP connection: load average = %.2f\n",
240 (double)load_average/1000.0);
241 smtp_printf("421 Too much load; please try again later.\r\n", FALSE);
242 log_write(L_connection_reject,
243 LOG_MAIN, "Connection from %s refused: load average = %.2f",
244 whofrom->s, (double)load_average/1000.0);
245 goto ERROR_RETURN;
246 }
247 }
248
249 /* Check that one specific host (strictly, IP address) is not hogging
250 resources. This is done here to prevent a denial of service attack by someone
251 forcing you to fork lots of times before denying service. The value of
252 smtp_accept_max_per_host is a string which is expanded. This makes it possible
253 to provide host-specific limits according to $sender_host address, but because
254 this is in the daemon mainline, only fast expansions (such as inline address
255 checks) should be used. The documentation is full of warnings. */
256
257 if (smtp_accept_max_per_host != NULL)
258 {
259 uschar *expanded = expand_string(smtp_accept_max_per_host);
260 if (expanded == NULL)
261 {
262 if (!f.expand_string_forcedfail)
263 log_write(0, LOG_MAIN|LOG_PANIC, "expansion of smtp_accept_max_per_host "
264 "failed for %s: %s", whofrom->s, expand_string_message);
265 }
266 /* For speed, interpret a decimal number inline here */
267 else
268 {
269 uschar *s = expanded;
270 while (isdigit(*s))
271 max_for_this_host = max_for_this_host * 10 + *s++ - '0';
272 if (*s != 0)
273 log_write(0, LOG_MAIN|LOG_PANIC, "expansion of smtp_accept_max_per_host "
274 "for %s contains non-digit: %s", whofrom->s, expanded);
275 }
276 }
277
278 /* If we have fewer connections than max_for_this_host, we can skip the tedious
279 per host_address checks. Note that at this stage smtp_accept_count contains the
280 count of *other* connections, not including this one. */
281
282 if ((max_for_this_host > 0) &&
283 (smtp_accept_count >= max_for_this_host))
284 {
285 int i;
286 int host_accept_count = 0;
287 int other_host_count = 0; /* keep a count of non matches to optimise */
288
289 for (i = 0; i < smtp_accept_max; ++i)
290 if (smtp_slots[i].host_address)
291 {
292 if (Ustrcmp(sender_host_address, smtp_slots[i].host_address) == 0)
293 host_accept_count++;
294 else
295 other_host_count++;
296
297 /* Testing all these strings is expensive - see if we can drop out
298 early, either by hitting the target, or finding there are not enough
299 connections left to make the target. */
300
301 if ((host_accept_count >= max_for_this_host) ||
302 ((smtp_accept_count - other_host_count) < max_for_this_host))
303 break;
304 }
305
306 if (host_accept_count >= max_for_this_host)
307 {
308 DEBUG(D_any) debug_printf("rejecting SMTP connection: too many from this "
309 "IP address: count=%d max=%d\n",
310 host_accept_count, max_for_this_host);
311 smtp_printf("421 Too many concurrent SMTP connections "
312 "from this IP address; please try again later.\r\n", FALSE);
313 log_write(L_connection_reject,
314 LOG_MAIN, "Connection from %s refused: too many connections "
315 "from that IP address", whofrom->s);
316 goto ERROR_RETURN;
317 }
318 }
319
320 /* OK, the connection count checks have been passed. Before we can fork the
321 accepting process, we must first log the connection if requested. This logging
322 used to happen in the subprocess, but doing that means that the value of
323 smtp_accept_count can be out of step by the time it is logged. So we have to do
324 the logging here and accept the performance cost. Note that smtp_accept_count
325 hasn't yet been incremented to take account of this connection.
326
327 In order to minimize the cost (because this is going to happen for every
328 connection), do a preliminary selector test here. This saves ploughing through
329 the generalized logging code each time when the selector is false. If the
330 selector is set, check whether the host is on the list for logging. If not,
331 arrange to unset the selector in the subprocess. */
332
333 if (LOGGING(smtp_connection))
334 {
335 uschar *list = hosts_connection_nolog;
336 memset(sender_host_cache, 0, sizeof(sender_host_cache));
337 if (list != NULL && verify_check_host(&list) == OK)
338 save_log_selector &= ~L_smtp_connection;
339 else
340 log_write(L_smtp_connection, LOG_MAIN, "SMTP connection from %s "
341 "(TCP/IP connection count = %d)", whofrom->s, smtp_accept_count + 1);
342 }
343
344 /* Now we can fork the accepting process; do a lookup tidy, just in case any
345 expansion above did a lookup. */
346
347 search_tidyup();
348 pid = fork();
349
350 /* Handle the child process */
351
352 if (pid == 0)
353 {
354 int i;
355 int queue_only_reason = 0;
356 int old_pool = store_pool;
357 int save_debug_selector = debug_selector;
358 BOOL local_queue_only;
359 BOOL session_local_queue_only;
360 #ifdef SA_NOCLDWAIT
361 struct sigaction act;
362 #endif
363
364 smtp_accept_count++; /* So that it includes this process */
365
366 /* May have been modified for the subprocess */
367
368 *log_selector = save_log_selector;
369
370 /* Get the local interface address into permanent store */
371
372 store_pool = POOL_PERM;
373 interface_address = string_copy(interface_address);
374 store_pool = old_pool;
375
376 /* Check for a tls-on-connect port */
377
378 if (host_is_tls_on_connect_port(interface_port)) tls_in.on_connect = TRUE;
379
380 /* Expand smtp_active_hostname if required. We do not do this any earlier,
381 because it may depend on the local interface address (indeed, that is most
382 likely what it depends on.) */
383
384 smtp_active_hostname = primary_hostname;
385 if (raw_active_hostname)
386 {
387 uschar * nah = expand_string(raw_active_hostname);
388 if (!nah)
389 {
390 if (!f.expand_string_forcedfail)
391 {
392 log_write(0, LOG_MAIN|LOG_PANIC, "failed to expand \"%s\" "
393 "(smtp_active_hostname): %s", raw_active_hostname,
394 expand_string_message);
395 smtp_printf("421 Local configuration error; "
396 "please try again later.\r\n", FALSE);
397 mac_smtp_fflush();
398 search_tidyup();
399 _exit(EXIT_FAILURE);
400 }
401 }
402 else if (*nah) smtp_active_hostname = nah;
403 }
404
405 /* Initialize the queueing flags */
406
407 queue_check_only();
408 session_local_queue_only = queue_only;
409
410 /* Close the listening sockets, and set the SIGCHLD handler to SIG_IGN.
411 We also attempt to set things up so that children are automatically reaped,
412 but just in case this isn't available, there's a paranoid waitpid() in the
413 loop too (except for systems where we are sure it isn't needed). See the more
414 extensive comment before the reception loop in exim.c for a fuller
415 explanation of this logic. */
416
417 for (i = 0; i < listen_socket_count; i++) (void)close(listen_sockets[i]);
418
419 /* Set FD_CLOEXEC on the SMTP socket. We don't want any rogue child processes
420 to be able to communicate with them, under any circumstances. */
421 (void)fcntl(accept_socket, F_SETFD,
422 fcntl(accept_socket, F_GETFD) | FD_CLOEXEC);
423 (void)fcntl(dup_accept_socket, F_SETFD,
424 fcntl(dup_accept_socket, F_GETFD) | FD_CLOEXEC);
425
426 #ifdef SA_NOCLDWAIT
427 act.sa_handler = SIG_IGN;
428 sigemptyset(&(act.sa_mask));
429 act.sa_flags = SA_NOCLDWAIT;
430 sigaction(SIGCHLD, &act, NULL);
431 #else
432 signal(SIGCHLD, SIG_IGN);
433 #endif
434
435 /* Attempt to get an id from the sending machine via the RFC 1413
436 protocol. We do this in the sub-process in order not to hold up the
437 main process if there is any delay. Then set up the fullhost information
438 in case there is no HELO/EHLO.
439
440 If debugging is enabled only for the daemon, we must turn if off while
441 finding the id, but turn it on again afterwards so that information about the
442 incoming connection is output. */
443
444 if (f.debug_daemon) debug_selector = 0;
445 verify_get_ident(IDENT_PORT);
446 host_build_sender_fullhost();
447 debug_selector = save_debug_selector;
448
449 DEBUG(D_any)
450 debug_printf("Process %d is handling incoming connection from %s\n",
451 (int)getpid(), sender_fullhost);
452
453 /* Now disable debugging permanently if it's required only for the daemon
454 process. */
455
456 if (f.debug_daemon) debug_selector = 0;
457
458 /* If there are too many child processes for immediate delivery,
459 set the session_local_queue_only flag, which is initialized from the
460 configured value and may therefore already be TRUE. Leave logging
461 till later so it will have a message id attached. Note that there is no
462 possibility of re-calculating this per-message, because the value of
463 smtp_accept_count does not change in this subprocess. */
464
465 if (smtp_accept_queue > 0 && smtp_accept_count > smtp_accept_queue)
466 {
467 session_local_queue_only = TRUE;
468 queue_only_reason = 1;
469 }
470
471 /* Handle the start of the SMTP session, then loop, accepting incoming
472 messages from the SMTP connection. The end will come at the QUIT command,
473 when smtp_setup_msg() returns 0. A break in the connection causes the
474 process to die (see accept.c).
475
476 NOTE: We do *not* call smtp_log_no_mail() if smtp_start_session() fails,
477 because a log line has already been written for all its failure exists
478 (usually "connection refused: <reason>") and writing another one is
479 unnecessary clutter. */
480
481 if (!smtp_start_session())
482 {
483 mac_smtp_fflush();
484 search_tidyup();
485 _exit(EXIT_SUCCESS);
486 }
487
488 for (;;)
489 {
490 int rc;
491 message_id[0] = 0; /* Clear out any previous message_id */
492 reset_point = store_get(0); /* Save current store high water point */
493
494 DEBUG(D_any)
495 debug_printf("Process %d is ready for new message\n", (int)getpid());
496
497 /* Smtp_setup_msg() returns 0 on QUIT or if the call is from an
498 unacceptable host or if an ACL "drop" command was triggered, -1 on
499 connection lost, and +1 on validly reaching DATA. Receive_msg() almost
500 always returns TRUE when smtp_input is true; just retry if no message was
501 accepted (can happen for invalid message parameters). However, it can yield
502 FALSE if the connection was forcibly dropped by the DATA ACL. */
503
504 if ((rc = smtp_setup_msg()) > 0)
505 {
506 BOOL ok = receive_msg(FALSE);
507 search_tidyup(); /* Close cached databases */
508 if (!ok) /* Connection was dropped */
509 {
510 cancel_cutthrough_connection(TRUE, US"receive dropped");
511 mac_smtp_fflush();
512 smtp_log_no_mail(); /* Log no mail if configured */
513 _exit(EXIT_SUCCESS);
514 }
515 if (message_id[0] == 0) continue; /* No message was accepted */
516 }
517 else
518 {
519 if (smtp_out)
520 {
521 int i, fd = fileno(smtp_in);
522 uschar buf[128];
523
524 mac_smtp_fflush();
525 /* drain socket, for clean TCP FINs */
526 if (fcntl(fd, F_SETFL, O_NONBLOCK) == 0)
527 for(i = 16; read(fd, buf, sizeof(buf)) > 0 && i > 0; ) i--;
528 }
529 cancel_cutthrough_connection(TRUE, US"message setup dropped");
530 search_tidyup();
531 smtp_log_no_mail(); /* Log no mail if configured */
532
533 /*XXX should we pause briefly, hoping that the client will be the
534 active TCP closer hence get the TCP_WAIT endpoint? */
535 DEBUG(D_receive) debug_printf("SMTP>>(close on process exit)\n");
536 _exit(rc ? EXIT_FAILURE : EXIT_SUCCESS);
537 }
538
539 /* Show the recipients when debugging */
540
541 DEBUG(D_receive)
542 {
543 int i;
544 if (sender_address)
545 debug_printf("Sender: %s\n", sender_address);
546 if (recipients_list)
547 {
548 debug_printf("Recipients:\n");
549 for (i = 0; i < recipients_count; i++)
550 debug_printf(" %s\n", recipients_list[i].address);
551 }
552 }
553
554 /* A message has been accepted. Clean up any previous delivery processes
555 that have completed and are defunct, on systems where they don't go away
556 by themselves (see comments when setting SIG_IGN above). On such systems
557 (if any) these delivery processes hang around after termination until
558 the next message is received. */
559
560 #ifndef SIG_IGN_WORKS
561 while (waitpid(-1, NULL, WNOHANG) > 0);
562 #endif
563
564 /* Reclaim up the store used in accepting this message */
565
566 {
567 int r = receive_messagecount;
568 BOOL q = f.queue_only_policy;
569 smtp_reset(reset_point);
570 f.queue_only_policy = q;
571 receive_messagecount = r;
572 }
573
574 /* If queue_only is set or if there are too many incoming connections in
575 existence, session_local_queue_only will be TRUE. If it is not, check
576 whether we have received too many messages in this session for immediate
577 delivery. */
578
579 if (!session_local_queue_only &&
580 smtp_accept_queue_per_connection > 0 &&
581 receive_messagecount > smtp_accept_queue_per_connection)
582 {
583 session_local_queue_only = TRUE;
584 queue_only_reason = 2;
585 }
586
587 /* Initialize local_queue_only from session_local_queue_only. If it is not
588 true, and queue_only_load is set, check that the load average is below it.
589 If local_queue_only is set by this means, we also set if for the session if
590 queue_only_load_latch is true (the default). This means that, once set,
591 local_queue_only remains set for any subsequent messages on the same SMTP
592 connection. This is a deliberate choice; even though the load average may
593 fall, it doesn't seem right to deliver later messages on the same call when
594 not delivering earlier ones. However, the are special circumstances such as
595 very long-lived connections from scanning appliances where this is not the
596 best strategy. In such cases, queue_only_load_latch should be set false. */
597
598 if ( !(local_queue_only = session_local_queue_only)
599 && queue_only_load >= 0
600 && (local_queue_only = (load_average = OS_GETLOADAVG()) > queue_only_load)
601 )
602 {
603 queue_only_reason = 3;
604 if (queue_only_load_latch) session_local_queue_only = TRUE;
605 }
606
607 /* Log the queueing here, when it will get a message id attached, but
608 not if queue_only is set (case 0). */
609
610 if (local_queue_only) switch(queue_only_reason)
611 {
612 case 1: log_write(L_delay_delivery,
613 LOG_MAIN, "no immediate delivery: too many connections "
614 "(%d, max %d)", smtp_accept_count, smtp_accept_queue);
615 break;
616
617 case 2: log_write(L_delay_delivery,
618 LOG_MAIN, "no immediate delivery: more than %d messages "
619 "received in one connection", smtp_accept_queue_per_connection);
620 break;
621
622 case 3: log_write(L_delay_delivery,
623 LOG_MAIN, "no immediate delivery: load average %.2f",
624 (double)load_average/1000.0);
625 break;
626 }
627
628 /* If a delivery attempt is required, spin off a new process to handle it.
629 If we are not root, we have to re-exec exim unless deliveries are being
630 done unprivileged. */
631
632 else if (!f.queue_only_policy && !f.deliver_freeze)
633 {
634 pid_t dpid;
635
636 /* Before forking, ensure that the C output buffer is flushed. Otherwise
637 anything that it in it will get duplicated, leading to duplicate copies
638 of the pending output. */
639
640 mac_smtp_fflush();
641
642 if ((dpid = fork()) == 0)
643 {
644 (void)fclose(smtp_in);
645 (void)fclose(smtp_out);
646
647 /* Don't ever molest the parent's SSL connection, but do clean up
648 the data structures if necessary. */
649
650 #ifdef SUPPORT_TLS
651 tls_close(NULL, TLS_NO_SHUTDOWN);
652 #endif
653
654 /* Reset SIGHUP and SIGCHLD in the child in both cases. */
655
656 signal(SIGHUP, SIG_DFL);
657 signal(SIGCHLD, SIG_DFL);
658
659 if (geteuid() != root_uid && !deliver_drop_privilege)
660 {
661 signal(SIGALRM, SIG_DFL);
662 delivery_re_exec(CEE_EXEC_PANIC);
663 /* Control does not return here. */
664 }
665
666 /* No need to re-exec; SIGALRM remains set to the default handler */
667
668 (void) deliver_message(message_id, FALSE, FALSE);
669 search_tidyup();
670 _exit(EXIT_SUCCESS);
671 }
672
673 if (dpid > 0)
674 {
675 release_cutthrough_connection(US"passed for delivery");
676 DEBUG(D_any) debug_printf("forked delivery process %d\n", (int)dpid);
677 }
678 else
679 {
680 cancel_cutthrough_connection(TRUE, US"delivery fork failed");
681 log_write(0, LOG_MAIN|LOG_PANIC, "daemon: delivery process fork "
682 "failed: %s", strerror(errno));
683 }
684 }
685 }
686 }
687
688
689 /* Carrying on in the parent daemon process... Can't do much if the fork
690 failed. Otherwise, keep count of the number of accepting processes and
691 remember the pid for ticking off when the child completes. */
692
693 if (pid < 0)
694 never_error(US"daemon: accept process fork failed", US"Fork failed", errno);
695 else
696 {
697 int i;
698 for (i = 0; i < smtp_accept_max; ++i)
699 if (smtp_slots[i].pid <= 0)
700 {
701 smtp_slots[i].pid = pid;
702 if (smtp_accept_max_per_host != NULL)
703 smtp_slots[i].host_address = string_copy_malloc(sender_host_address);
704 smtp_accept_count++;
705 break;
706 }
707 DEBUG(D_any) debug_printf("%d SMTP accept process%s running\n",
708 smtp_accept_count, (smtp_accept_count == 1)? "" : "es");
709 }
710
711 /* Get here via goto in error cases */
712
713 ERROR_RETURN:
714
715 /* Close the streams associated with the socket which will also close the
716 socket fds in this process. We can't do anything if fclose() fails, but
717 logging brings it to someone's attention. However, "connection reset by peer"
718 isn't really a problem, so skip that one. On Solaris, a dropped connection can
719 manifest itself as a broken pipe, so drop that one too. If the streams don't
720 exist, something went wrong while setting things up. Make sure the socket
721 descriptors are closed, in order to drop the connection. */
722
723 if (smtp_out)
724 {
725 if (fclose(smtp_out) != 0 && errno != ECONNRESET && errno != EPIPE)
726 log_write(0, LOG_MAIN|LOG_PANIC, "daemon: fclose(smtp_out) failed: %s",
727 strerror(errno));
728 smtp_out = NULL;
729 }
730 else (void)close(accept_socket);
731
732 if (smtp_in)
733 {
734 if (fclose(smtp_in) != 0 && errno != ECONNRESET && errno != EPIPE)
735 log_write(0, LOG_MAIN|LOG_PANIC, "daemon: fclose(smtp_in) failed: %s",
736 strerror(errno));
737 smtp_in = NULL;
738 }
739 else (void)close(dup_accept_socket);
740
741 /* Release any store used in this process, including the store used for holding
742 the incoming host address and an expanded active_hostname. */
743
744 log_close_all();
745 interface_address =
746 sender_host_address = NULL;
747 store_reset(reset_point);
748 sender_host_address = NULL;
749 }
750
751
752
753
754 /*************************************************
755 * Check wildcard listen special cases *
756 *************************************************/
757
758 /* This function is used when binding and listening on lists of addresses and
759 ports. It tests for special cases of wildcard listening, when IPv4 and IPv6
760 sockets may interact in different ways in different operating systems. It is
761 passed an error number, the list of listening addresses, and the current
762 address. Two checks are available: for a previous wildcard IPv6 address, or for
763 a following wildcard IPv4 address, in both cases on the same port.
764
765 In practice, pairs of wildcard addresses should be adjacent in the address list
766 because they are sorted that way below.
767
768 Arguments:
769 eno the error number
770 addresses the list of addresses
771 ipa the current IP address
772 back if TRUE, check for previous wildcard IPv6 address
773 if FALSE, check for a following wildcard IPv4 address
774
775 Returns: TRUE or FALSE
776 */
777
778 static BOOL
779 check_special_case(int eno, ip_address_item *addresses, ip_address_item *ipa,
780 BOOL back)
781 {
782 ip_address_item *ipa2;
783
784 /* For the "back" case, if the failure was "address in use" for a wildcard IPv4
785 address, seek a previous IPv6 wildcard address on the same port. As it is
786 previous, it must have been successfully bound and be listening. Flag it as a
787 "6 including 4" listener. */
788
789 if (back)
790 {
791 if (eno != EADDRINUSE || ipa->address[0] != 0) return FALSE;
792 for (ipa2 = addresses; ipa2 != ipa; ipa2 = ipa2->next)
793 {
794 if (ipa2->address[1] == 0 && ipa2->port == ipa->port)
795 {
796 ipa2->v6_include_v4 = TRUE;
797 return TRUE;
798 }
799 }
800 }
801
802 /* For the "forward" case, if the current address is a wildcard IPv6 address,
803 we seek a following wildcard IPv4 address on the same port. */
804
805 else
806 {
807 if (ipa->address[0] != ':' || ipa->address[1] != 0) return FALSE;
808 for (ipa2 = ipa->next; ipa2 != NULL; ipa2 = ipa2->next)
809 if (ipa2->address[0] == 0 && ipa->port == ipa2->port) return TRUE;
810 }
811
812 return FALSE;
813 }
814
815
816
817
818 /*************************************************
819 * Handle terminating subprocesses *
820 *************************************************/
821
822 /* Handle the termination of child processes. Theoretically, this need be done
823 only when sigchld_seen is TRUE, but rumour has it that some systems lose
824 SIGCHLD signals at busy times, so to be on the safe side, this function is
825 called each time round. It shouldn't be too expensive.
826
827 Arguments: none
828 Returns: nothing
829 */
830
831 static void
832 handle_ending_processes(void)
833 {
834 int status;
835 pid_t pid;
836
837 while ((pid = waitpid(-1, &status, WNOHANG)) > 0)
838 {
839 int i;
840 DEBUG(D_any)
841 {
842 debug_printf("child %d ended: status=0x%x\n", (int)pid, status);
843 #ifdef WCOREDUMP
844 if (WIFEXITED(status))
845 debug_printf(" normal exit, %d\n", WEXITSTATUS(status));
846 else if (WIFSIGNALED(status))
847 debug_printf(" signal exit, signal %d%s\n", WTERMSIG(status),
848 WCOREDUMP(status) ? " (core dumped)" : "");
849 #endif
850 }
851
852 /* If it's a listening daemon for which we are keeping track of individual
853 subprocesses, deal with an accepting process that has terminated. */
854
855 if (smtp_slots)
856 {
857 for (i = 0; i < smtp_accept_max; i++)
858 if (smtp_slots[i].pid == pid)
859 {
860 if (smtp_slots[i].host_address)
861 store_free(smtp_slots[i].host_address);
862 smtp_slots[i] = empty_smtp_slot;
863 if (--smtp_accept_count < 0) smtp_accept_count = 0;
864 DEBUG(D_any) debug_printf("%d SMTP accept process%s now running\n",
865 smtp_accept_count, (smtp_accept_count == 1)? "" : "es");
866 break;
867 }
868 if (i < smtp_accept_max) continue; /* Found an accepting process */
869 }
870
871 /* If it wasn't an accepting process, see if it was a queue-runner
872 process that we are tracking. */
873
874 if (queue_pid_slots)
875 {
876 int max = atoi(CS expand_string(queue_run_max));
877 for (i = 0; i < max; i++)
878 if (queue_pid_slots[i] == pid)
879 {
880 queue_pid_slots[i] = 0;
881 if (--queue_run_count < 0) queue_run_count = 0;
882 DEBUG(D_any) debug_printf("%d queue-runner process%s now running\n",
883 queue_run_count, (queue_run_count == 1)? "" : "es");
884 break;
885 }
886 }
887 }
888 }
889
890
891
892 /*************************************************
893 * Exim Daemon Mainline *
894 *************************************************/
895
896 /* The daemon can do two jobs, either of which is optional:
897
898 (1) Listens for incoming SMTP calls and spawns off a sub-process to handle
899 each one. This is requested by the -bd option, with -oX specifying the SMTP
900 port on which to listen (for testing).
901
902 (2) Spawns a queue-running process every so often. This is controlled by the
903 -q option with a an interval time. (If no time is given, a single queue run
904 is done from the main function, and control doesn't get here.)
905
906 Root privilege is required in order to attach to port 25. Some systems require
907 it when calling socket() rather than bind(). To cope with all cases, we run as
908 root for both socket() and bind(). Some systems also require root in order to
909 write to the pid file directory. This function must therefore be called as root
910 if it is to work properly in all circumstances. Once the socket is bound and
911 the pid file written, root privilege is given up if there is an exim uid.
912
913 There are no arguments to this function, and it never returns. */
914
915 void
916 daemon_go(void)
917 {
918 struct passwd *pw;
919 int *listen_sockets = NULL;
920 int listen_socket_count = 0;
921 ip_address_item *addresses = NULL;
922 time_t last_connection_time = (time_t)0;
923 int local_queue_run_max = atoi(CS expand_string(queue_run_max));
924
925 /* If any debugging options are set, turn on the D_pid bit so that all
926 debugging lines get the pid added. */
927
928 DEBUG(D_any|D_v) debug_selector |= D_pid;
929
930 if (f.inetd_wait_mode)
931 {
932 listen_socket_count = 1;
933 listen_sockets = store_get(sizeof(int));
934 (void) close(3);
935 if (dup2(0, 3) == -1)
936 log_write(0, LOG_MAIN|LOG_PANIC_DIE,
937 "failed to dup inetd socket safely away: %s", strerror(errno));
938
939 listen_sockets[0] = 3;
940 (void) close(0);
941 (void) close(1);
942 (void) close(2);
943 exim_nullstd();
944
945 if (debug_file == stderr)
946 {
947 /* need a call to log_write before call to open debug_file, so that
948 log.c:file_path has been initialised. This is unfortunate. */
949 log_write(0, LOG_MAIN, "debugging Exim in inetd wait mode starting");
950
951 fclose(debug_file);
952 debug_file = NULL;
953 exim_nullstd(); /* re-open fd2 after we just closed it again */
954 debug_logging_activate(US"-wait", NULL);
955 }
956
957 DEBUG(D_any) debug_printf("running in inetd wait mode\n");
958
959 /* As per below, when creating sockets ourselves, we handle tcp_nodelay for
960 our own buffering; we assume though that inetd set the socket REUSEADDR. */
961
962 if (tcp_nodelay)
963 if (setsockopt(3, IPPROTO_TCP, TCP_NODELAY, US &on, sizeof(on)))
964 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "failed to set socket NODELAY: %s",
965 strerror(errno));
966 }
967
968
969 if (f.inetd_wait_mode || f.daemon_listen)
970 {
971 /* If any option requiring a load average to be available during the
972 reception of a message is set, call os_getloadavg() while we are root
973 for those OS for which this is necessary the first time it is called (in
974 order to perform an "open" on the kernel memory file). */
975
976 #ifdef LOAD_AVG_NEEDS_ROOT
977 if (queue_only_load >= 0 || smtp_load_reserve >= 0 ||
978 (deliver_queue_load_max >= 0 && deliver_drop_privilege))
979 (void)os_getloadavg();
980 #endif
981 }
982
983
984 /* Do the preparation for setting up a listener on one or more interfaces, and
985 possible on various ports. This is controlled by the combination of
986 local_interfaces (which can set IP addresses and ports) and daemon_smtp_port
987 (which is a list of default ports to use for those items in local_interfaces
988 that do not specify a port). The -oX command line option can be used to
989 override one or both of these options.
990
991 If local_interfaces is not set, the default is to listen on all interfaces.
992 When it is set, it can include "all IPvx interfaces" as an item. This is useful
993 when different ports are in use.
994
995 It turns out that listening on all interfaces is messy in an IPv6 world,
996 because several different implementation approaches have been taken. This code
997 is now supposed to work with all of them. The point of difference is whether an
998 IPv6 socket that is listening on all interfaces will receive incoming IPv4
999 calls or not. We also have to cope with the case when IPv6 libraries exist, but
1000 there is no IPv6 support in the kernel.
1001
1002 . On Solaris, an IPv6 socket will accept IPv4 calls, and give them as mapped
1003 addresses. However, if an IPv4 socket is also listening on all interfaces,
1004 calls are directed to the appropriate socket.
1005
1006 . On (some versions of) Linux, an IPv6 socket will accept IPv4 calls, and
1007 give them as mapped addresses, but an attempt also to listen on an IPv4
1008 socket on all interfaces causes an error.
1009
1010 . On OpenBSD, an IPv6 socket will not accept IPv4 calls. You have to set up
1011 two sockets if you want to accept both kinds of call.
1012
1013 . FreeBSD is like OpenBSD, but it has the IPV6_V6ONLY socket option, which
1014 can be turned off, to make it behave like the versions of Linux described
1015 above.
1016
1017 . I heard a report that the USAGI IPv6 stack for Linux has implemented
1018 IPV6_V6ONLY.
1019
1020 So, what we do when IPv6 is supported is as follows:
1021
1022 (1) After it is set up, the list of interfaces is scanned for wildcard
1023 addresses. If an IPv6 and an IPv4 wildcard are both found for the same
1024 port, the list is re-arranged so that they are together, with the IPv6
1025 wildcard first.
1026
1027 (2) If the creation of a wildcard IPv6 socket fails, we just log the error and
1028 carry on if an IPv4 wildcard socket for the same port follows later in the
1029 list. This allows Exim to carry on in the case when the kernel has no IPv6
1030 support.
1031
1032 (3) Having created an IPv6 wildcard socket, we try to set IPV6_V6ONLY if that
1033 option is defined. However, if setting fails, carry on regardless (but log
1034 the incident).
1035
1036 (4) If binding or listening on an IPv6 wildcard socket fails, it is a serious
1037 error.
1038
1039 (5) If binding or listening on an IPv4 wildcard socket fails with the error
1040 EADDRINUSE, and a previous interface was an IPv6 wildcard for the same
1041 port (which must have succeeded or we wouldn't have got this far), we
1042 assume we are in the situation where just a single socket is permitted,
1043 and ignore the error.
1044
1045 Phew!
1046
1047 The preparation code decodes options and sets up the relevant data. We do this
1048 first, so that we can return non-zero if there are any syntax errors, and also
1049 write to stderr. */
1050
1051 if (f.daemon_listen && !f.inetd_wait_mode)
1052 {
1053 int *default_smtp_port;
1054 int sep;
1055 int pct = 0;
1056 uschar *s;
1057 const uschar * list;
1058 uschar *local_iface_source = US"local_interfaces";
1059 ip_address_item *ipa;
1060 ip_address_item **pipa;
1061
1062 /* If -oX was used, disable the writing of a pid file unless -oP was
1063 explicitly used to force it. Then scan the string given to -oX. Any items
1064 that contain neither a dot nor a colon are used to override daemon_smtp_port.
1065 Any other items are used to override local_interfaces. */
1066
1067 if (override_local_interfaces)
1068 {
1069 gstring * new_smtp_port = NULL;
1070 gstring * new_local_interfaces = NULL;
1071
1072 if (override_pid_file_path == NULL) write_pid = FALSE;
1073
1074 list = override_local_interfaces;
1075 sep = 0;
1076 while ((s = string_nextinlist(&list, &sep, big_buffer, big_buffer_size)))
1077 {
1078 uschar joinstr[4];
1079 gstring ** gp;
1080
1081 if (Ustrpbrk(s, ".:") == NULL)
1082 gp = &new_smtp_port;
1083 else
1084 gp = &new_local_interfaces;
1085
1086 if (!*gp)
1087 {
1088 joinstr[0] = sep;
1089 joinstr[1] = ' ';
1090 *gp = string_catn(*gp, US"<", 1);
1091 }
1092
1093 *gp = string_catn(*gp, joinstr, 2);
1094 *gp = string_cat (*gp, s);
1095 }
1096
1097 if (new_smtp_port)
1098 {
1099 daemon_smtp_port = string_from_gstring(new_smtp_port);
1100 DEBUG(D_any) debug_printf("daemon_smtp_port overridden by -oX:\n %s\n",
1101 daemon_smtp_port);
1102 }
1103
1104 if (new_local_interfaces)
1105 {
1106 local_interfaces = string_from_gstring(new_local_interfaces);
1107 local_iface_source = US"-oX data";
1108 DEBUG(D_any) debug_printf("local_interfaces overridden by -oX:\n %s\n",
1109 local_interfaces);
1110 }
1111 }
1112
1113 /* Create a list of default SMTP ports, to be used if local_interfaces
1114 contains entries without explicit ports. First count the number of ports, then
1115 build a translated list in a vector. */
1116
1117 list = daemon_smtp_port;
1118 sep = 0;
1119 while ((s = string_nextinlist(&list, &sep, big_buffer, big_buffer_size)))
1120 pct++;
1121 default_smtp_port = store_get((pct+1) * sizeof(int));
1122 list = daemon_smtp_port;
1123 sep = 0;
1124 for (pct = 0;
1125 (s = string_nextinlist(&list, &sep, big_buffer, big_buffer_size));
1126 pct++)
1127 {
1128 if (isdigit(*s))
1129 {
1130 uschar *end;
1131 default_smtp_port[pct] = Ustrtol(s, &end, 0);
1132 if (end != s + Ustrlen(s))
1133 log_write(0, LOG_PANIC_DIE|LOG_CONFIG, "invalid SMTP port: %s", s);
1134 }
1135 else
1136 {
1137 struct servent *smtp_service = getservbyname(CS s, "tcp");
1138 if (!smtp_service)
1139 log_write(0, LOG_PANIC_DIE|LOG_CONFIG, "TCP port \"%s\" not found", s);
1140 default_smtp_port[pct] = ntohs(smtp_service->s_port);
1141 }
1142 }
1143 default_smtp_port[pct] = 0;
1144
1145 /* Check the list of TLS-on-connect ports and do name lookups if needed */
1146
1147 list = tls_in.on_connect_ports;
1148 sep = 0;
1149 while ((s = string_nextinlist(&list, &sep, big_buffer, big_buffer_size)))
1150 if (!isdigit(*s))
1151 {
1152 gstring * g = NULL;
1153
1154 list = tls_in.on_connect_ports;
1155 tls_in.on_connect_ports = NULL;
1156 sep = 0;
1157 while ((s = string_nextinlist(&list, &sep, big_buffer, big_buffer_size)))
1158 {
1159 if (!isdigit(*s))
1160 {
1161 struct servent * smtp_service = getservbyname(CS s, "tcp");
1162 if (!smtp_service)
1163 log_write(0, LOG_PANIC_DIE|LOG_CONFIG, "TCP port \"%s\" not found", s);
1164 s = string_sprintf("%d", (int)ntohs(smtp_service->s_port));
1165 }
1166 g = string_append_listele(g, ':', s);
1167 }
1168 if (g)
1169 tls_in.on_connect_ports = g->s;
1170 break;
1171 }
1172
1173 /* Create the list of local interfaces, possibly with ports included. This
1174 list may contain references to 0.0.0.0 and ::0 as wildcards. These special
1175 values are converted below. */
1176
1177 addresses = host_build_ifacelist(local_interfaces, local_iface_source);
1178
1179 /* In the list of IP addresses, convert 0.0.0.0 into an empty string, and ::0
1180 into the string ":". We use these to recognize wildcards in IPv4 and IPv6. In
1181 fact, many IP stacks recognize 0.0.0.0 and ::0 and handle them as wildcards
1182 anyway, but we need to know which are the wildcard addresses, and the shorter
1183 strings are neater.
1184
1185 In the same scan, fill in missing port numbers from the default list. When
1186 there is more than one item in the list, extra items are created. */
1187
1188 for (ipa = addresses; ipa; ipa = ipa->next)
1189 {
1190 int i;
1191
1192 if (Ustrcmp(ipa->address, "0.0.0.0") == 0)
1193 ipa->address[0] = 0;
1194 else if (Ustrcmp(ipa->address, "::0") == 0)
1195 {
1196 ipa->address[0] = ':';
1197 ipa->address[1] = 0;
1198 }
1199
1200 if (ipa->port > 0) continue;
1201
1202 if (daemon_smtp_port[0] <= 0)
1203 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "no port specified for interface "
1204 "%s and daemon_smtp_port is unset; cannot start daemon",
1205 ipa->address[0] == 0 ? US"\"all IPv4\"" :
1206 ipa->address[1] == 0 ? US"\"all IPv6\"" : ipa->address);
1207
1208 ipa->port = default_smtp_port[0];
1209 for (i = 1; default_smtp_port[i] > 0; i++)
1210 {
1211 ip_address_item *new = store_get(sizeof(ip_address_item));
1212
1213 memcpy(new->address, ipa->address, Ustrlen(ipa->address) + 1);
1214 new->port = default_smtp_port[i];
1215 new->next = ipa->next;
1216 ipa->next = new;
1217 ipa = new;
1218 }
1219 }
1220
1221 /* Scan the list of addresses for wildcards. If we find an IPv4 and an IPv6
1222 wildcard for the same port, ensure that (a) they are together and (b) the
1223 IPv6 address comes first. This makes handling the messy features easier, and
1224 also simplifies the construction of the "daemon started" log line. */
1225
1226 pipa = &addresses;
1227 for (ipa = addresses; ipa; pipa = &ipa->next, ipa = ipa->next)
1228 {
1229 ip_address_item *ipa2;
1230
1231 /* Handle an IPv4 wildcard */
1232
1233 if (ipa->address[0] == 0)
1234 for (ipa2 = ipa; ipa2->next; ipa2 = ipa2->next)
1235 {
1236 ip_address_item *ipa3 = ipa2->next;
1237 if (ipa3->address[0] == ':' &&
1238 ipa3->address[1] == 0 &&
1239 ipa3->port == ipa->port)
1240 {
1241 ipa2->next = ipa3->next;
1242 ipa3->next = ipa;
1243 *pipa = ipa3;
1244 break;
1245 }
1246 }
1247
1248 /* Handle an IPv6 wildcard. */
1249
1250 else if (ipa->address[0] == ':' && ipa->address[1] == 0)
1251 for (ipa2 = ipa; ipa2->next; ipa2 = ipa2->next)
1252 {
1253 ip_address_item *ipa3 = ipa2->next;
1254 if (ipa3->address[0] == 0 && ipa3->port == ipa->port)
1255 {
1256 ipa2->next = ipa3->next;
1257 ipa3->next = ipa->next;
1258 ipa->next = ipa3;
1259 ipa = ipa3;
1260 break;
1261 }
1262 }
1263 }
1264
1265 /* Get a vector to remember all the sockets in */
1266
1267 for (ipa = addresses; ipa; ipa = ipa->next)
1268 listen_socket_count++;
1269 listen_sockets = store_get(sizeof(int) * listen_socket_count);
1270
1271 } /* daemon_listen but not inetd_wait_mode */
1272
1273 if (f.daemon_listen)
1274 {
1275
1276 /* Do a sanity check on the max connects value just to save us from getting
1277 a huge amount of store. */
1278
1279 if (smtp_accept_max > 4095) smtp_accept_max = 4096;
1280
1281 /* There's no point setting smtp_accept_queue unless it is less than the max
1282 connects limit. The configuration reader ensures that the max is set if the
1283 queue-only option is set. */
1284
1285 if (smtp_accept_queue > smtp_accept_max) smtp_accept_queue = 0;
1286
1287 /* Get somewhere to keep the list of SMTP accepting pids if we are keeping
1288 track of them for total number and queue/host limits. */
1289
1290 if (smtp_accept_max > 0)
1291 {
1292 int i;
1293 smtp_slots = store_get(smtp_accept_max * sizeof(smtp_slot));
1294 for (i = 0; i < smtp_accept_max; i++) smtp_slots[i] = empty_smtp_slot;
1295 }
1296 }
1297
1298 /* The variable background_daemon is always false when debugging, but
1299 can also be forced false in order to keep a non-debugging daemon in the
1300 foreground. If background_daemon is true, close all open file descriptors that
1301 we know about, but then re-open stdin, stdout, and stderr to /dev/null. Also
1302 do this for inetd_wait mode.
1303
1304 This is protection against any called functions (in libraries, or in
1305 Perl, or whatever) that think they can write to stderr (or stdout). Before this
1306 was added, it was quite likely that an SMTP connection would use one of these
1307 file descriptors, in which case writing random stuff to it caused chaos.
1308
1309 Then disconnect from the controlling terminal, Most modern Unixes seem to have
1310 setsid() for getting rid of the controlling terminal. For any OS that doesn't,
1311 setsid() can be #defined as a no-op, or as something else. */
1312
1313 if (f.background_daemon || f.inetd_wait_mode)
1314 {
1315 log_close_all(); /* Just in case anything was logged earlier */
1316 search_tidyup(); /* Just in case any were used in reading the config. */
1317 (void)close(0); /* Get rid of stdin/stdout/stderr */
1318 (void)close(1);
1319 (void)close(2);
1320 exim_nullstd(); /* Connect stdin/stdout/stderr to /dev/null */
1321 log_stderr = NULL; /* So no attempt to copy paniclog output */
1322 }
1323
1324 if (f.background_daemon)
1325 {
1326 /* If the parent process of this one has pid == 1, we are re-initializing the
1327 daemon as the result of a SIGHUP. In this case, there is no need to do
1328 anything, because the controlling terminal has long gone. Otherwise, fork, in
1329 case current process is a process group leader (see 'man setsid' for an
1330 explanation) before calling setsid(). */
1331
1332 if (getppid() != 1)
1333 {
1334 pid_t pid = fork();
1335 if (pid < 0) log_write(0, LOG_MAIN|LOG_PANIC_DIE,
1336 "fork() failed when starting daemon: %s", strerror(errno));
1337 if (pid > 0) exit(EXIT_SUCCESS); /* in parent process, just exit */
1338 (void)setsid(); /* release controlling terminal */
1339 }
1340 }
1341
1342 /* We are now in the disconnected, daemon process (unless debugging). Set up
1343 the listening sockets if required. */
1344
1345 if (f.daemon_listen && !f.inetd_wait_mode)
1346 {
1347 int sk;
1348 ip_address_item *ipa;
1349
1350 /* For each IP address, create a socket, bind it to the appropriate port, and
1351 start listening. See comments above about IPv6 sockets that may or may not
1352 accept IPv4 calls when listening on all interfaces. We also have to cope with
1353 the case of a system with IPv6 libraries, but no IPv6 support in the kernel.
1354 listening, provided a wildcard IPv4 socket for the same port follows. */
1355
1356 for (ipa = addresses, sk = 0; sk < listen_socket_count; ipa = ipa->next, sk++)
1357 {
1358 BOOL wildcard;
1359 ip_address_item *ipa2;
1360 int af;
1361
1362 if (Ustrchr(ipa->address, ':') != NULL)
1363 {
1364 af = AF_INET6;
1365 wildcard = ipa->address[1] == 0;
1366 }
1367 else
1368 {
1369 af = AF_INET;
1370 wildcard = ipa->address[0] == 0;
1371 }
1372
1373 if ((listen_sockets[sk] = ip_socket(SOCK_STREAM, af)) < 0)
1374 {
1375 if (check_special_case(0, addresses, ipa, FALSE))
1376 {
1377 log_write(0, LOG_MAIN, "Failed to create IPv6 socket for wildcard "
1378 "listening (%s): will use IPv4", strerror(errno));
1379 goto SKIP_SOCKET;
1380 }
1381 log_write(0, LOG_PANIC_DIE, "IPv%c socket creation failed: %s",
1382 (af == AF_INET6)? '6' : '4', strerror(errno));
1383 }
1384
1385 /* If this is an IPv6 wildcard socket, set IPV6_V6ONLY if that option is
1386 available. Just log failure (can get protocol not available, just like
1387 socket creation can). */
1388
1389 #ifdef IPV6_V6ONLY
1390 if (af == AF_INET6 && wildcard &&
1391 setsockopt(listen_sockets[sk], IPPROTO_IPV6, IPV6_V6ONLY, CS (&on),
1392 sizeof(on)) < 0)
1393 log_write(0, LOG_MAIN, "Setting IPV6_V6ONLY on daemon's IPv6 wildcard "
1394 "socket failed (%s): carrying on without it", strerror(errno));
1395 #endif /* IPV6_V6ONLY */
1396
1397 /* Set SO_REUSEADDR so that the daemon can be restarted while a connection
1398 is being handled. Without this, a connection will prevent reuse of the
1399 smtp port for listening. */
1400
1401 if (setsockopt(listen_sockets[sk], SOL_SOCKET, SO_REUSEADDR,
1402 US (&on), sizeof(on)) < 0)
1403 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "setting SO_REUSEADDR on socket "
1404 "failed when starting daemon: %s", strerror(errno));
1405
1406 /* Set TCP_NODELAY; Exim does its own buffering. There is a switch to
1407 disable this because it breaks some broken clients. */
1408
1409 if (tcp_nodelay) setsockopt(listen_sockets[sk], IPPROTO_TCP, TCP_NODELAY,
1410 US (&on), sizeof(on));
1411
1412 /* Now bind the socket to the required port; if Exim is being restarted
1413 it may not always be possible to bind immediately, even with SO_REUSEADDR
1414 set, so try 10 times, waiting between each try. After 10 failures, we give
1415 up. In an IPv6 environment, if bind () fails with the error EADDRINUSE and
1416 we are doing wildcard IPv4 listening and there was a previous IPv6 wildcard
1417 address for the same port, ignore the error on the grounds that we must be
1418 in a system where the IPv6 socket accepts both kinds of call. This is
1419 necessary for (some release of) USAGI Linux; other IP stacks fail at the
1420 listen() stage instead. */
1421
1422 #ifdef TCP_FASTOPEN
1423 f.tcp_fastopen_ok = TRUE;
1424 #endif
1425 for(;;)
1426 {
1427 uschar *msg, *addr;
1428 if (ip_bind(listen_sockets[sk], af, ipa->address, ipa->port) >= 0) break;
1429 if (check_special_case(errno, addresses, ipa, TRUE))
1430 {
1431 DEBUG(D_any) debug_printf("wildcard IPv4 bind() failed after IPv6 "
1432 "listen() success; EADDRINUSE ignored\n");
1433 (void)close(listen_sockets[sk]);
1434 goto SKIP_SOCKET;
1435 }
1436 msg = US strerror(errno);
1437 addr = wildcard
1438 ? af == AF_INET6
1439 ? US"(any IPv6)"
1440 : US"(any IPv4)"
1441 : ipa->address;
1442 if (daemon_startup_retries <= 0)
1443 log_write(0, LOG_MAIN|LOG_PANIC_DIE,
1444 "socket bind() to port %d for address %s failed: %s: "
1445 "daemon abandoned", ipa->port, addr, msg);
1446 log_write(0, LOG_MAIN, "socket bind() to port %d for address %s "
1447 "failed: %s: waiting %s before trying again (%d more %s)",
1448 ipa->port, addr, msg, readconf_printtime(daemon_startup_sleep),
1449 daemon_startup_retries, (daemon_startup_retries > 1)? "tries" : "try");
1450 daemon_startup_retries--;
1451 sleep(daemon_startup_sleep);
1452 }
1453
1454 DEBUG(D_any)
1455 if (wildcard)
1456 debug_printf("listening on all interfaces (IPv%c) port %d\n",
1457 af == AF_INET6 ? '6' : '4', ipa->port);
1458 else
1459 debug_printf("listening on %s port %d\n", ipa->address, ipa->port);
1460
1461 #ifdef TCP_FASTOPEN
1462 if (setsockopt(listen_sockets[sk], IPPROTO_TCP, TCP_FASTOPEN,
1463 &smtp_connect_backlog, sizeof(smtp_connect_backlog)))
1464 {
1465 DEBUG(D_any) debug_printf("setsockopt FASTOPEN: %s\n", strerror(errno));
1466 f.tcp_fastopen_ok = FALSE;
1467 }
1468 #endif
1469
1470 /* Start listening on the bound socket, establishing the maximum backlog of
1471 connections that is allowed. On success, continue to the next address. */
1472
1473 if (listen(listen_sockets[sk], smtp_connect_backlog) >= 0) continue;
1474
1475 /* Listening has failed. In an IPv6 environment, as for bind(), if listen()
1476 fails with the error EADDRINUSE and we are doing IPv4 wildcard listening
1477 and there was a previous successful IPv6 wildcard listen on the same port,
1478 we want to ignore the error on the grounds that we must be in a system
1479 where the IPv6 socket accepts both kinds of call. */
1480
1481 if (!check_special_case(errno, addresses, ipa, TRUE))
1482 log_write(0, LOG_PANIC_DIE, "listen() failed on interface %s: %s",
1483 wildcard
1484 ? af == AF_INET6 ? US"(any IPv6)" : US"(any IPv4)" : ipa->address,
1485 strerror(errno));
1486
1487 DEBUG(D_any) debug_printf("wildcard IPv4 listen() failed after IPv6 "
1488 "listen() success; EADDRINUSE ignored\n");
1489 (void)close(listen_sockets[sk]);
1490
1491 /* Come here if there has been a problem with the socket which we
1492 are going to ignore. We remove the address from the chain, and back up the
1493 counts. */
1494
1495 SKIP_SOCKET:
1496 sk--; /* Back up the count */
1497 listen_socket_count--; /* Reduce the total */
1498 if (ipa == addresses) addresses = ipa->next; else
1499 {
1500 for (ipa2 = addresses; ipa2->next != ipa; ipa2 = ipa2->next);
1501 ipa2->next = ipa->next;
1502 ipa = ipa2;
1503 }
1504 } /* End of bind/listen loop for each address */
1505 } /* End of setup for listening */
1506
1507
1508 /* If we are not listening, we want to write a pid file only if -oP was
1509 explicitly given. */
1510
1511 else if (!override_pid_file_path)
1512 write_pid = FALSE;
1513
1514 /* Write the pid to a known file for assistance in identification, if required.
1515 We do this before giving up root privilege, because on some systems it is
1516 necessary to be root in order to write into the pid file directory. There's
1517 nothing to stop multiple daemons running, as long as no more than one listens
1518 on a given TCP/IP port on the same interface(s). However, in these
1519 circumstances it gets far too complicated to mess with pid file names
1520 automatically. Consequently, Exim 4 writes a pid file only
1521
1522 (a) When running in the test harness, or
1523 (b) When -bd is used and -oX is not used, or
1524 (c) When -oP is used to supply a path.
1525
1526 The variable daemon_write_pid is used to control this. */
1527
1528 if (f.running_in_test_harness || write_pid)
1529 {
1530 FILE *f;
1531
1532 if (override_pid_file_path)
1533 pid_file_path = override_pid_file_path;
1534
1535 if (pid_file_path[0] == 0)
1536 pid_file_path = string_sprintf("%s/exim-daemon.pid", spool_directory);
1537
1538 if ((f = modefopen(pid_file_path, "wb", 0644)))
1539 {
1540 (void)fprintf(f, "%d\n", (int)getpid());
1541 (void)fclose(f);
1542 DEBUG(D_any) debug_printf("pid written to %s\n", pid_file_path);
1543 }
1544 else
1545 DEBUG(D_any)
1546 debug_printf("%s\n", string_open_failed(errno, "pid file %s",
1547 pid_file_path));
1548 }
1549
1550 /* Set up the handler for SIGHUP, which causes a restart of the daemon. */
1551
1552 sighup_seen = FALSE;
1553 signal(SIGHUP, sighup_handler);
1554
1555 /* Give up root privilege at this point (assuming that exim_uid and exim_gid
1556 are not root). The third argument controls the running of initgroups().
1557 Normally we do this, in order to set up the groups for the Exim user. However,
1558 if we are not root at this time - some odd installations run that way - we
1559 cannot do this. */
1560
1561 exim_setugid(exim_uid, exim_gid, geteuid()==root_uid, US"running as a daemon");
1562
1563 /* Update the originator_xxx fields so that received messages as listed as
1564 coming from Exim, not whoever started the daemon. */
1565
1566 originator_uid = exim_uid;
1567 originator_gid = exim_gid;
1568 originator_login = ((pw = getpwuid(exim_uid)) != NULL)?
1569 string_copy_malloc(US pw->pw_name) : US"exim";
1570
1571 /* Get somewhere to keep the list of queue-runner pids if we are keeping track
1572 of them (and also if we are doing queue runs). */
1573
1574 if (queue_interval > 0 && local_queue_run_max > 0)
1575 {
1576 int i;
1577 queue_pid_slots = store_get(local_queue_run_max * sizeof(pid_t));
1578 for (i = 0; i < local_queue_run_max; i++) queue_pid_slots[i] = 0;
1579 }
1580
1581 /* Set up the handler for termination of child processes. */
1582
1583 sigchld_seen = FALSE;
1584 os_non_restarting_signal(SIGCHLD, main_sigchld_handler);
1585
1586 /* If we are to run the queue periodically, pretend the alarm has just gone
1587 off. This will cause the first queue-runner to get kicked off straight away. */
1588
1589 sigalrm_seen = (queue_interval > 0);
1590
1591 /* Log the start up of a daemon - at least one of listening or queue running
1592 must be set up. */
1593
1594 if (f.inetd_wait_mode)
1595 {
1596 uschar *p = big_buffer;
1597
1598 if (inetd_wait_timeout >= 0)
1599 sprintf(CS p, "terminating after %d seconds", inetd_wait_timeout);
1600 else
1601 sprintf(CS p, "with no wait timeout");
1602
1603 log_write(0, LOG_MAIN,
1604 "exim %s daemon started: pid=%d, launched with listening socket, %s",
1605 version_string, getpid(), big_buffer);
1606 set_process_info("daemon(%s): pre-listening socket", version_string);
1607
1608 /* set up the timeout logic */
1609 sigalrm_seen = 1;
1610 }
1611
1612 else if (f.daemon_listen)
1613 {
1614 int i, j;
1615 int smtp_ports = 0;
1616 int smtps_ports = 0;
1617 ip_address_item * ipa, * i2;
1618 uschar * p = big_buffer;
1619 uschar * qinfo = queue_interval > 0
1620 ? string_sprintf("-q%s", readconf_printtime(queue_interval))
1621 : US"no queue runs";
1622
1623 /* Build a list of listening addresses in big_buffer, but limit it to 10
1624 items. The style is for backwards compatibility.
1625
1626 It is now possible to have some ports listening for SMTPS (the old,
1627 deprecated protocol that starts TLS without using STARTTLS), and others
1628 listening for standard SMTP. Keep their listings separate. */
1629
1630 for (j = 0; j < 2; j++)
1631 {
1632 for (i = 0, ipa = addresses; i < 10 && ipa; i++, ipa = ipa->next)
1633 {
1634 /* First time round, look for SMTP ports; second time round, look for
1635 SMTPS ports. For the first one of each, insert leading text. */
1636
1637 if (host_is_tls_on_connect_port(ipa->port) == (j > 0))
1638 {
1639 if (j == 0)
1640 {
1641 if (smtp_ports++ == 0)
1642 {
1643 memcpy(p, "SMTP on", 8);
1644 p += 7;
1645 }
1646 }
1647 else
1648 if (smtps_ports++ == 0)
1649 p += sprintf(CS p, "%sSMTPS on",
1650 smtp_ports == 0 ? "" : " and for ");
1651
1652 /* Now the information about the port (and sometimes interface) */
1653
1654 if (ipa->address[0] == ':' && ipa->address[1] == 0)
1655 { /* v6 wildcard */
1656 if (ipa->next && ipa->next->address[0] == 0 &&
1657 ipa->next->port == ipa->port)
1658 {
1659 p += sprintf(CS p, " port %d (IPv6 and IPv4)", ipa->port);
1660 ipa = ipa->next;
1661 }
1662 else if (ipa->v6_include_v4)
1663 p += sprintf(CS p, " port %d (IPv6 with IPv4)", ipa->port);
1664 else
1665 p += sprintf(CS p, " port %d (IPv6)", ipa->port);
1666 }
1667 else if (ipa->address[0] == 0) /* v4 wildcard */
1668 p += sprintf(CS p, " port %d (IPv4)", ipa->port);
1669 else /* check for previously-seen IP */
1670 {
1671 for (i2 = addresses; i2 != ipa; i2 = i2->next)
1672 if ( host_is_tls_on_connect_port(i2->port) == (j > 0)
1673 && Ustrcmp(ipa->address, i2->address) == 0
1674 )
1675 { /* found; append port to list */
1676 if (p[-1] == '}') p--;
1677 while (isdigit(*--p)) ;
1678 p += 1 + sprintf(CS p+1, "%s%d,%d}", *p == ',' ? "" : "{",
1679 i2->port, ipa->port);
1680 break;
1681 }
1682 if (i2 == ipa) /* first-time IP */
1683 p += sprintf(CS p, " [%s]:%d", ipa->address, ipa->port);
1684 }
1685 }
1686 }
1687
1688 if (ipa)
1689 {
1690 memcpy(p, " ...", 5);
1691 p += 4;
1692 }
1693 }
1694
1695 log_write(0, LOG_MAIN,
1696 "exim %s daemon started: pid=%d, %s, listening for %s",
1697 version_string, getpid(), qinfo, big_buffer);
1698 set_process_info("daemon(%s): %s, listening for %s",
1699 version_string, qinfo, big_buffer);
1700 }
1701
1702 else
1703 {
1704 uschar * s = *queue_name
1705 ? string_sprintf("-qG%s/%s", queue_name, readconf_printtime(queue_interval))
1706 : string_sprintf("-q%s", readconf_printtime(queue_interval));
1707 log_write(0, LOG_MAIN,
1708 "exim %s daemon started: pid=%d, %s, not listening for SMTP",
1709 version_string, getpid(), s);
1710 set_process_info("daemon(%s): %s, not listening", version_string, s);
1711 }
1712
1713 /* Do any work it might be useful to amortize over our children
1714 (eg: compile regex) */
1715
1716 dns_pattern_init();
1717
1718 #ifdef WITH_CONTENT_SCAN
1719 malware_init();
1720 #endif
1721
1722 /* Close the log so it can be renamed and moved. In the few cases below where
1723 this long-running process writes to the log (always exceptional conditions), it
1724 closes the log afterwards, for the same reason. */
1725
1726 log_close_all();
1727
1728 DEBUG(D_any) debug_print_ids(US"daemon running with");
1729
1730 /* Any messages accepted via this route are going to be SMTP. */
1731
1732 smtp_input = TRUE;
1733
1734 /* Enter the never-ending loop... */
1735
1736 for (;;)
1737 {
1738 #if HAVE_IPV6
1739 struct sockaddr_in6 accepted;
1740 #else
1741 struct sockaddr_in accepted;
1742 #endif
1743
1744 EXIM_SOCKLEN_T len;
1745 pid_t pid;
1746
1747 /* This code is placed first in the loop, so that it gets obeyed at the
1748 start, before the first wait, for the queue-runner case, so that the first
1749 one can be started immediately.
1750
1751 The other option is that we have an inetd wait timeout specified to -bw. */
1752
1753 if (sigalrm_seen)
1754 {
1755 if (inetd_wait_timeout > 0)
1756 {
1757 time_t resignal_interval = inetd_wait_timeout;
1758
1759 if (last_connection_time == (time_t)0)
1760 {
1761 DEBUG(D_any)
1762 debug_printf("inetd wait timeout expired, but still not seen first message, ignoring\n");
1763 }
1764 else
1765 {
1766 time_t now = time(NULL);
1767 if (now == (time_t)-1)
1768 {
1769 DEBUG(D_any) debug_printf("failed to get time: %s\n", strerror(errno));
1770 }
1771 else
1772 {
1773 if ((now - last_connection_time) >= inetd_wait_timeout)
1774 {
1775 DEBUG(D_any)
1776 debug_printf("inetd wait timeout %d expired, ending daemon\n",
1777 inetd_wait_timeout);
1778 log_write(0, LOG_MAIN, "exim %s daemon terminating, inetd wait timeout reached.\n",
1779 version_string);
1780 exit(EXIT_SUCCESS);
1781 }
1782 else
1783 {
1784 resignal_interval -= (now - last_connection_time);
1785 }
1786 }
1787 }
1788
1789 sigalrm_seen = FALSE;
1790 alarm(resignal_interval);
1791 }
1792
1793 else
1794 {
1795 DEBUG(D_any) debug_printf("SIGALRM received\n");
1796
1797 /* Do a full queue run in a child process, if required, unless we already
1798 have enough queue runners on the go. If we are not running as root, a
1799 re-exec is required. */
1800
1801 if (queue_interval > 0 &&
1802 (local_queue_run_max <= 0 || queue_run_count < local_queue_run_max))
1803 {
1804 if ((pid = fork()) == 0)
1805 {
1806 int sk;
1807
1808 DEBUG(D_any) debug_printf("Starting queue-runner: pid %d\n",
1809 (int)getpid());
1810
1811 /* Disable debugging if it's required only for the daemon process. We
1812 leave the above message, because it ties up with the "child ended"
1813 debugging messages. */
1814
1815 if (f.debug_daemon) debug_selector = 0;
1816
1817 /* Close any open listening sockets in the child */
1818
1819 for (sk = 0; sk < listen_socket_count; sk++)
1820 (void)close(listen_sockets[sk]);
1821
1822 /* Reset SIGHUP and SIGCHLD in the child in both cases. */
1823
1824 signal(SIGHUP, SIG_DFL);
1825 signal(SIGCHLD, SIG_DFL);
1826
1827 /* Re-exec if privilege has been given up, unless deliver_drop_
1828 privilege is set. Reset SIGALRM before exec(). */
1829
1830 if (geteuid() != root_uid && !deliver_drop_privilege)
1831 {
1832 uschar opt[8];
1833 uschar *p = opt;
1834 uschar *extra[5];
1835 int extracount = 1;
1836
1837 signal(SIGALRM, SIG_DFL);
1838 *p++ = '-';
1839 *p++ = 'q';
1840 if (f.queue_2stage) *p++ = 'q';
1841 if (f.queue_run_first_delivery) *p++ = 'i';
1842 if (f.queue_run_force) *p++ = 'f';
1843 if (f.deliver_force_thaw) *p++ = 'f';
1844 if (f.queue_run_local) *p++ = 'l';
1845 *p = 0;
1846 extra[0] = queue_name
1847 ? string_sprintf("%sG%s", opt, queue_name) : opt;
1848
1849 /* If -R or -S were on the original command line, ensure they get
1850 passed on. */
1851
1852 if (deliver_selectstring)
1853 {
1854 extra[extracount++] = f.deliver_selectstring_regex ? US"-Rr" : US"-R";
1855 extra[extracount++] = deliver_selectstring;
1856 }
1857
1858 if (deliver_selectstring_sender)
1859 {
1860 extra[extracount++] = f.deliver_selectstring_sender_regex
1861 ? US"-Sr" : US"-S";
1862 extra[extracount++] = deliver_selectstring_sender;
1863 }
1864
1865 /* Overlay this process with a new execution. */
1866
1867 (void)child_exec_exim(CEE_EXEC_PANIC, FALSE, NULL, TRUE, extracount,
1868 extra[0], extra[1], extra[2], extra[3], extra[4]);
1869
1870 /* Control never returns here. */
1871 }
1872
1873 /* No need to re-exec; SIGALRM remains set to the default handler */
1874
1875 queue_run(NULL, NULL, FALSE);
1876 _exit(EXIT_SUCCESS);
1877 }
1878
1879 if (pid < 0)
1880 {
1881 log_write(0, LOG_MAIN|LOG_PANIC, "daemon: fork of queue-runner "
1882 "process failed: %s", strerror(errno));
1883 log_close_all();
1884 }
1885 else
1886 {
1887 int i;
1888 for (i = 0; i < local_queue_run_max; ++i)
1889 if (queue_pid_slots[i] <= 0)
1890 {
1891 queue_pid_slots[i] = pid;
1892 queue_run_count++;
1893 break;
1894 }
1895 DEBUG(D_any) debug_printf("%d queue-runner process%s running\n",
1896 queue_run_count, (queue_run_count == 1)? "" : "es");
1897 }
1898 }
1899
1900 /* Reset the alarm clock */
1901
1902 sigalrm_seen = FALSE;
1903 alarm(queue_interval);
1904 }
1905
1906 } /* sigalrm_seen */
1907
1908
1909 /* Sleep till a connection happens if listening, and handle the connection if
1910 that is why we woke up. The FreeBSD operating system requires the use of
1911 select() before accept() because the latter function is not interrupted by
1912 a signal, and we want to wake up for SIGCHLD and SIGALRM signals. Some other
1913 OS do notice signals in accept() but it does no harm to have the select()
1914 in for all of them - and it won't then be a lurking problem for ports to
1915 new OS. In fact, the later addition of listening on specific interfaces only
1916 requires this way of working anyway. */
1917
1918 if (f.daemon_listen)
1919 {
1920 int sk, lcount, select_errno;
1921 int max_socket = 0;
1922 BOOL select_failed = FALSE;
1923 fd_set select_listen;
1924
1925 FD_ZERO(&select_listen);
1926 for (sk = 0; sk < listen_socket_count; sk++)
1927 {
1928 FD_SET(listen_sockets[sk], &select_listen);
1929 if (listen_sockets[sk] > max_socket) max_socket = listen_sockets[sk];
1930 }
1931
1932 DEBUG(D_any) debug_printf("Listening...\n");
1933
1934 /* In rare cases we may have had a SIGCHLD signal in the time between
1935 setting the handler (below) and getting back here. If so, pretend that the
1936 select() was interrupted so that we reap the child. This might still leave
1937 a small window when a SIGCHLD could get lost. However, since we use SIGCHLD
1938 only to do the reaping more quickly, it shouldn't result in anything other
1939 than a delay until something else causes a wake-up. */
1940
1941 if (sigchld_seen)
1942 {
1943 lcount = -1;
1944 errno = EINTR;
1945 }
1946 else
1947 lcount = select(max_socket + 1, (SELECT_ARG2_TYPE *)&select_listen,
1948 NULL, NULL, NULL);
1949
1950 if (lcount < 0)
1951 {
1952 select_failed = TRUE;
1953 lcount = 1;
1954 }
1955
1956 /* Clean up any subprocesses that may have terminated. We need to do this
1957 here so that smtp_accept_max_per_host works when a connection to that host
1958 has completed, and we are about to accept a new one. When this code was
1959 later in the sequence, a new connection could be rejected, even though an
1960 old one had just finished. Preserve the errno from any select() failure for
1961 the use of the common select/accept error processing below. */
1962
1963 select_errno = errno;
1964 handle_ending_processes();
1965 errno = select_errno;
1966
1967 /* Loop for all the sockets that are currently ready to go. If select
1968 actually failed, we have set the count to 1 and select_failed=TRUE, so as
1969 to use the common error code for select/accept below. */
1970
1971 while (lcount-- > 0)
1972 {
1973 int accept_socket = -1;
1974
1975 if (!select_failed)
1976 for (sk = 0; sk < listen_socket_count; sk++)
1977 if (FD_ISSET(listen_sockets[sk], &select_listen))
1978 {
1979 len = sizeof(accepted);
1980 accept_socket = accept(listen_sockets[sk],
1981 (struct sockaddr *)&accepted, &len);
1982 FD_CLR(listen_sockets[sk], &select_listen);
1983 break;
1984 }
1985
1986 /* If select or accept has failed and this was not caused by an
1987 interruption, log the incident and try again. With asymmetric TCP/IP
1988 routing errors such as "No route to network" have been seen here. Also
1989 "connection reset by peer" has been seen. These cannot be classed as
1990 disastrous errors, but they could fill up a lot of log. The code in smail
1991 crashes the daemon after 10 successive failures of accept, on the grounds
1992 that some OS fail continuously. Exim originally followed suit, but this
1993 appears to have caused problems. Now it just keeps going, but instead of
1994 logging each error, it batches them up when they are continuous. */
1995
1996 if (accept_socket < 0 && errno != EINTR)
1997 {
1998 if (accept_retry_count == 0)
1999 {
2000 accept_retry_errno = errno;
2001 accept_retry_select_failed = select_failed;
2002 }
2003 else
2004 {
2005 if (errno != accept_retry_errno ||
2006 select_failed != accept_retry_select_failed ||
2007 accept_retry_count >= 50)
2008 {
2009 log_write(0, LOG_MAIN | ((accept_retry_count >= 50)? LOG_PANIC : 0),
2010 "%d %s() failure%s: %s",
2011 accept_retry_count,
2012 accept_retry_select_failed? "select" : "accept",
2013 (accept_retry_count == 1)? "" : "s",
2014 strerror(accept_retry_errno));
2015 log_close_all();
2016 accept_retry_count = 0;
2017 accept_retry_errno = errno;
2018 accept_retry_select_failed = select_failed;
2019 }
2020 }
2021 accept_retry_count++;
2022 }
2023
2024 else
2025 {
2026 if (accept_retry_count > 0)
2027 {
2028 log_write(0, LOG_MAIN, "%d %s() failure%s: %s",
2029 accept_retry_count,
2030 accept_retry_select_failed? "select" : "accept",
2031 (accept_retry_count == 1)? "" : "s",
2032 strerror(accept_retry_errno));
2033 log_close_all();
2034 accept_retry_count = 0;
2035 }
2036 }
2037
2038 /* If select/accept succeeded, deal with the connection. */
2039
2040 if (accept_socket >= 0)
2041 {
2042 if (inetd_wait_timeout)
2043 last_connection_time = time(NULL);
2044 handle_smtp_call(listen_sockets, listen_socket_count, accept_socket,
2045 (struct sockaddr *)&accepted);
2046 }
2047 }
2048 }
2049
2050 /* If not listening, then just sleep for the queue interval. If we woke
2051 up early the last time for some other signal, it won't matter because
2052 the alarm signal will wake at the right time. This code originally used
2053 sleep() but it turns out that on the FreeBSD system, sleep() is not inter-
2054 rupted by signals, so it wasn't waking up for SIGALRM or SIGCHLD. Luckily
2055 select() can be used as an interruptible sleep() on all versions of Unix. */
2056
2057 else
2058 {
2059 struct timeval tv;
2060 tv.tv_sec = queue_interval;
2061 tv.tv_usec = 0;
2062 select(0, NULL, NULL, NULL, &tv);
2063 handle_ending_processes();
2064 }
2065
2066 /* Re-enable the SIGCHLD handler if it has been run. It can't do it
2067 for itself, because it isn't doing the waiting itself. */
2068
2069 if (sigchld_seen)
2070 {
2071 sigchld_seen = FALSE;
2072 os_non_restarting_signal(SIGCHLD, main_sigchld_handler);
2073 }
2074
2075 /* Handle being woken by SIGHUP. We know at this point that the result
2076 of accept() has been dealt with, so we can re-exec exim safely, first
2077 closing the listening sockets so that they can be reused. Cancel any pending
2078 alarm in case it is just about to go off, and set SIGHUP to be ignored so
2079 that another HUP in quick succession doesn't clobber the new daemon before it
2080 gets going. All log files get closed by the close-on-exec flag; however, if
2081 the exec fails, we need to close the logs. */
2082
2083 if (sighup_seen)
2084 {
2085 int sk;
2086 log_write(0, LOG_MAIN, "pid %d: SIGHUP received: re-exec daemon",
2087 getpid());
2088 for (sk = 0; sk < listen_socket_count; sk++)
2089 (void)close(listen_sockets[sk]);
2090 alarm(0);
2091 signal(SIGHUP, SIG_IGN);
2092 sighup_argv[0] = exim_path;
2093 exim_nullstd();
2094 execv(CS exim_path, (char *const *)sighup_argv);
2095 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "pid %d: exec of %s failed: %s",
2096 getpid(), exim_path, strerror(errno));
2097 log_close_all();
2098 }
2099
2100 } /* End of main loop */
2101
2102 /* Control never reaches here */
2103 }
2104
2105 /* vi: aw ai sw=2
2106 */
2107 /* End of exim_daemon.c */