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