TFO: use IPPROTO_TCP not SOL_TCL for setsockopt, being present on more platforms
[exim.git] / src / src / daemon.c
1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
4
5 /* Copyright (c) University of Cambridge 1995 - 2016 */
6 /* See the file NOTICE for conditions of use and distribution. */
7
8 /* Functions concerned with running Exim as a daemon */
9
10
11 #include "exim.h"
12
13
14 /* Structure for holding data for each SMTP connection */
15
16 typedef struct smtp_slot {
17 pid_t pid; /* pid of the spawned reception process */
18 uschar *host_address; /* address of the client host */
19 } smtp_slot;
20
21 /* An empty slot for initializing (Standard C does not allow constructor
22 expressions in assigments except as initializers in declarations). */
23
24 static smtp_slot empty_smtp_slot = { 0, NULL };
25
26
27
28 /*************************************************
29 * Local static variables *
30 *************************************************/
31
32 static SIGNAL_BOOL sigchld_seen;
33 static SIGNAL_BOOL sighup_seen;
34
35 static int accept_retry_count = 0;
36 static int accept_retry_errno;
37 static BOOL accept_retry_select_failed;
38
39 static int queue_run_count = 0;
40 static pid_t *queue_pid_slots = NULL;
41 static smtp_slot *smtp_slots = NULL;
42
43 static BOOL write_pid = TRUE;
44
45
46
47 /*************************************************
48 * SIGHUP Handler *
49 *************************************************/
50
51 /* All this handler does is to set a flag and re-enable the signal.
52
53 Argument: the signal number
54 Returns: nothing
55 */
56
57 static void
58 sighup_handler(int sig)
59 {
60 sig = sig; /* Keep picky compilers happy */
61 sighup_seen = TRUE;
62 signal(SIGHUP, sighup_handler);
63 }
64
65
66
67 /*************************************************
68 * SIGCHLD handler for main daemon process *
69 *************************************************/
70
71 /* Don't re-enable the handler here, since we aren't doing the
72 waiting here. If the signal is re-enabled, there will just be an
73 infinite sequence of calls to this handler. The SIGCHLD signal is
74 used just as a means of waking up the daemon so that it notices
75 terminated subprocesses as soon as possible.
76
77 Argument: the signal number
78 Returns: nothing
79 */
80
81 static void
82 main_sigchld_handler(int sig)
83 {
84 sig = sig; /* Keep picky compilers happy */
85 os_non_restarting_signal(SIGCHLD, SIG_DFL);
86 sigchld_seen = TRUE;
87 }
88
89
90
91
92 /*************************************************
93 * Unexpected errors in SMTP calls *
94 *************************************************/
95
96 /* This function just saves a bit of repetitious coding.
97
98 Arguments:
99 log_msg Text of message to be logged
100 smtp_msg Text of SMTP error message
101 was_errno The failing errno
102
103 Returns: nothing
104 */
105
106 static void
107 never_error(uschar *log_msg, uschar *smtp_msg, int was_errno)
108 {
109 uschar *emsg = (was_errno <= 0)? US"" :
110 string_sprintf(": %s", strerror(was_errno));
111 log_write(0, LOG_MAIN|LOG_PANIC, "%s%s", log_msg, emsg);
112 if (smtp_out != NULL) smtp_printf("421 %s\r\n", smtp_msg);
113 }
114
115
116
117
118 /*************************************************
119 * Handle a connected SMTP call *
120 *************************************************/
121
122 /* This function is called when an SMTP connection has been accepted.
123 If there are too many, give an error message and close down. Otherwise
124 spin off a sub-process to handle the call. The list of listening sockets
125 is required so that they can be closed in the sub-process. Take care not to
126 leak store in this process - reset the stacking pool at the end.
127
128 Arguments:
129 listen_sockets sockets which are listening for incoming calls
130 listen_socket_count count of listening sockets
131 accept_socket socket of the current accepted call
132 accepted socket information about the current call
133
134 Returns: nothing
135 */
136
137 static void
138 handle_smtp_call(int *listen_sockets, int listen_socket_count,
139 int accept_socket, struct sockaddr *accepted)
140 {
141 pid_t pid;
142 union sockaddr_46 interface_sockaddr;
143 EXIM_SOCKLEN_T ifsize = sizeof(interface_sockaddr);
144 int dup_accept_socket = -1;
145 int max_for_this_host = 0;
146 int wfsize = 0;
147 int wfptr = 0;
148 int save_log_selector = *log_selector;
149 uschar *whofrom = NULL;
150
151 void *reset_point = store_get(0);
152
153 /* Make the address available in ASCII representation, and also fish out
154 the remote port. */
155
156 sender_host_address = host_ntoa(-1, accepted, NULL, &sender_host_port);
157 DEBUG(D_any) debug_printf("Connection request from %s port %d\n",
158 sender_host_address, sender_host_port);
159
160 /* Set up the output stream, check the socket has duplicated, and set up the
161 input stream. These operations fail only the exceptional circumstances. Note
162 that never_error() won't use smtp_out if it is NULL. */
163
164 if (!(smtp_out = fdopen(accept_socket, "wb")))
165 {
166 never_error(US"daemon: fdopen() for smtp_out failed", US"", errno);
167 goto ERROR_RETURN;
168 }
169
170 if ((dup_accept_socket = dup(accept_socket)) < 0)
171 {
172 never_error(US"daemon: couldn't dup socket descriptor",
173 US"Connection setup failed", errno);
174 goto ERROR_RETURN;
175 }
176
177 if (!(smtp_in = fdopen(dup_accept_socket, "rb")))
178 {
179 never_error(US"daemon: fdopen() for smtp_in failed",
180 US"Connection setup failed", errno);
181 goto ERROR_RETURN;
182 }
183
184 /* Get the data for the local interface address. Panic for most errors, but
185 "connection reset by peer" just means the connection went away. */
186
187 if (getsockname(accept_socket, (struct sockaddr *)(&interface_sockaddr),
188 &ifsize) < 0)
189 {
190 log_write(0, LOG_MAIN | ((errno == ECONNRESET)? 0 : LOG_PANIC),
191 "getsockname() failed: %s", strerror(errno));
192 smtp_printf("421 Local problem: getsockname() failed; please try again later\r\n");
193 goto ERROR_RETURN;
194 }
195
196 interface_address = host_ntoa(-1, &interface_sockaddr, NULL, &interface_port);
197 DEBUG(D_interface) debug_printf("interface address=%s port=%d\n",
198 interface_address, interface_port);
199
200 /* Build a string identifying the remote host and, if requested, the port and
201 the local interface data. This is for logging; at the end of this function the
202 memory is reclaimed. */
203
204 whofrom = string_append(whofrom, &wfsize, &wfptr, 3, "[", sender_host_address, "]");
205
206 if (LOGGING(incoming_port))
207 whofrom = string_append(whofrom, &wfsize, &wfptr, 2, ":", string_sprintf("%d",
208 sender_host_port));
209
210 if (LOGGING(incoming_interface))
211 whofrom = string_append(whofrom, &wfsize, &wfptr, 4, " I=[",
212 interface_address, "]:", string_sprintf("%d", interface_port));
213
214 whofrom[wfptr] = 0; /* Terminate the newly-built string */
215
216 /* Check maximum number of connections. We do not check for reserved
217 connections or unacceptable hosts here. That is done in the subprocess because
218 it might take some time. */
219
220 if (smtp_accept_max > 0 && smtp_accept_count >= smtp_accept_max)
221 {
222 DEBUG(D_any) debug_printf("rejecting SMTP connection: count=%d max=%d\n",
223 smtp_accept_count, smtp_accept_max);
224 smtp_printf("421 Too many concurrent SMTP connections; "
225 "please try again later.\r\n");
226 log_write(L_connection_reject,
227 LOG_MAIN, "Connection from %s refused: too many connections",
228 whofrom);
229 goto ERROR_RETURN;
230 }
231
232 /* If a load limit above which only reserved hosts are acceptable is defined,
233 get the load average here, and if there are in fact no reserved hosts, do
234 the test right away (saves a fork). If there are hosts, do the check in the
235 subprocess because it might take time. */
236
237 if (smtp_load_reserve >= 0)
238 {
239 load_average = OS_GETLOADAVG();
240 if (smtp_reserve_hosts == NULL && load_average > smtp_load_reserve)
241 {
242 DEBUG(D_any) debug_printf("rejecting SMTP connection: load average = %.2f\n",
243 (double)load_average/1000.0);
244 smtp_printf("421 Too much load; please try again later.\r\n");
245 log_write(L_connection_reject,
246 LOG_MAIN, "Connection from %s refused: load average = %.2f",
247 whofrom, (double)load_average/1000.0);
248 goto ERROR_RETURN;
249 }
250 }
251
252 /* Check that one specific host (strictly, IP address) is not hogging
253 resources. This is done here to prevent a denial of service attack by someone
254 forcing you to fork lots of times before denying service. The value of
255 smtp_accept_max_per_host is a string which is expanded. This makes it possible
256 to provide host-specific limits according to $sender_host address, but because
257 this is in the daemon mainline, only fast expansions (such as inline address
258 checks) should be used. The documentation is full of warnings. */
259
260 if (smtp_accept_max_per_host != NULL)
261 {
262 uschar *expanded = expand_string(smtp_accept_max_per_host);
263 if (expanded == NULL)
264 {
265 if (!expand_string_forcedfail)
266 log_write(0, LOG_MAIN|LOG_PANIC, "expansion of smtp_accept_max_per_host "
267 "failed for %s: %s", whofrom, expand_string_message);
268 }
269 /* For speed, interpret a decimal number inline here */
270 else
271 {
272 uschar *s = expanded;
273 while (isdigit(*s))
274 max_for_this_host = max_for_this_host * 10 + *s++ - '0';
275 if (*s != 0)
276 log_write(0, LOG_MAIN|LOG_PANIC, "expansion of smtp_accept_max_per_host "
277 "for %s contains non-digit: %s", whofrom, expanded);
278 }
279 }
280
281 /* If we have fewer connections than max_for_this_host, we can skip the tedious
282 per host_address checks. Note that at this stage smtp_accept_count contains the
283 count of *other* connections, not including this one. */
284
285 if ((max_for_this_host > 0) &&
286 (smtp_accept_count >= max_for_this_host))
287 {
288 int i;
289 int host_accept_count = 0;
290 int other_host_count = 0; /* keep a count of non matches to optimise */
291
292 for (i = 0; i < smtp_accept_max; ++i)
293 if (smtp_slots[i].host_address != NULL)
294 {
295 if (Ustrcmp(sender_host_address, smtp_slots[i].host_address) == 0)
296 host_accept_count++;
297 else
298 other_host_count++;
299
300 /* Testing all these strings is expensive - see if we can drop out
301 early, either by hitting the target, or finding there are not enough
302 connections left to make the target. */
303
304 if ((host_accept_count >= max_for_this_host) ||
305 ((smtp_accept_count - other_host_count) < max_for_this_host))
306 break;
307 }
308
309 if (host_accept_count >= max_for_this_host)
310 {
311 DEBUG(D_any) debug_printf("rejecting SMTP connection: too many from this "
312 "IP address: count=%d max=%d\n",
313 host_accept_count, max_for_this_host);
314 smtp_printf("421 Too many concurrent SMTP connections "
315 "from this IP address; please try again later.\r\n");
316 log_write(L_connection_reject,
317 LOG_MAIN, "Connection from %s refused: too many connections "
318 "from that IP address", whofrom);
319 goto ERROR_RETURN;
320 }
321 }
322
323 /* OK, the connection count checks have been passed. Before we can fork the
324 accepting process, we must first log the connection if requested. This logging
325 used to happen in the subprocess, but doing that means that the value of
326 smtp_accept_count can be out of step by the time it is logged. So we have to do
327 the logging here and accept the performance cost. Note that smtp_accept_count
328 hasn't yet been incremented to take account of this connection.
329
330 In order to minimize the cost (because this is going to happen for every
331 connection), do a preliminary selector test here. This saves ploughing through
332 the generalized logging code each time when the selector is false. If the
333 selector is set, check whether the host is on the list for logging. If not,
334 arrange to unset the selector in the subprocess. */
335
336 if (LOGGING(smtp_connection))
337 {
338 uschar *list = hosts_connection_nolog;
339 memset(sender_host_cache, 0, sizeof(sender_host_cache));
340 if (list != NULL && verify_check_host(&list) == OK)
341 save_log_selector &= ~L_smtp_connection;
342 else
343 log_write(L_smtp_connection, LOG_MAIN, "SMTP connection from %s "
344 "(TCP/IP connection count = %d)", whofrom, smtp_accept_count + 1);
345 }
346
347 /* Now we can fork the accepting process; do a lookup tidy, just in case any
348 expansion above did a lookup. */
349
350 search_tidyup();
351 pid = fork();
352
353 /* Handle the child process */
354
355 if (pid == 0)
356 {
357 int i;
358 int queue_only_reason = 0;
359 int old_pool = store_pool;
360 int save_debug_selector = debug_selector;
361 BOOL local_queue_only;
362 BOOL session_local_queue_only;
363 #ifdef SA_NOCLDWAIT
364 struct sigaction act;
365 #endif
366
367 smtp_accept_count++; /* So that it includes this process */
368
369 /* May have been modified for the subprocess */
370
371 *log_selector = save_log_selector;
372
373 /* Get the local interface address into permanent store */
374
375 store_pool = POOL_PERM;
376 interface_address = string_copy(interface_address);
377 store_pool = old_pool;
378
379 /* Check for a tls-on-connect port */
380
381 if (host_is_tls_on_connect_port(interface_port)) tls_in.on_connect = TRUE;
382
383 /* Expand smtp_active_hostname if required. We do not do this any earlier,
384 because it may depend on the local interface address (indeed, that is most
385 likely what it depends on.) */
386
387 smtp_active_hostname = primary_hostname;
388 if (raw_active_hostname)
389 {
390 uschar * nah = expand_string(raw_active_hostname);
391 if (!nah)
392 {
393 if (!expand_string_forcedfail)
394 {
395 log_write(0, LOG_MAIN|LOG_PANIC, "failed to expand \"%s\" "
396 "(smtp_active_hostname): %s", raw_active_hostname,
397 expand_string_message);
398 smtp_printf("421 Local configuration error; "
399 "please try again later.\r\n");
400 mac_smtp_fflush();
401 search_tidyup();
402 _exit(EXIT_FAILURE);
403 }
404 }
405 else if (*nah) smtp_active_hostname = nah;
406 }
407
408 /* Initialize the queueing flags */
409
410 queue_check_only();
411 session_local_queue_only = queue_only;
412
413 /* Close the listening sockets, and set the SIGCHLD handler to SIG_IGN.
414 We also attempt to set things up so that children are automatically reaped,
415 but just in case this isn't available, there's a paranoid waitpid() in the
416 loop too (except for systems where we are sure it isn't needed). See the more
417 extensive comment before the reception loop in exim.c for a fuller
418 explanation of this logic. */
419
420 for (i = 0; i < listen_socket_count; i++) (void)close(listen_sockets[i]);
421
422 /* Set FD_CLOEXEC on the SMTP socket. We don't want any rogue child processes
423 to be able to communicate with them, under any circumstances. */
424 (void)fcntl(accept_socket, F_SETFD,
425 fcntl(accept_socket, F_GETFD) | FD_CLOEXEC);
426 (void)fcntl(dup_accept_socket, F_SETFD,
427 fcntl(dup_accept_socket, F_GETFD) | FD_CLOEXEC);
428
429 #ifdef SA_NOCLDWAIT
430 act.sa_handler = SIG_IGN;
431 sigemptyset(&(act.sa_mask));
432 act.sa_flags = SA_NOCLDWAIT;
433 sigaction(SIGCHLD, &act, NULL);
434 #else
435 signal(SIGCHLD, SIG_IGN);
436 #endif
437
438 /* Attempt to get an id from the sending machine via the RFC 1413
439 protocol. We do this in the sub-process in order not to hold up the
440 main process if there is any delay. Then set up the fullhost information
441 in case there is no HELO/EHLO.
442
443 If debugging is enabled only for the daemon, we must turn if off while
444 finding the id, but turn it on again afterwards so that information about the
445 incoming connection is output. */
446
447 if (debug_daemon) debug_selector = 0;
448 verify_get_ident(IDENT_PORT);
449 host_build_sender_fullhost();
450 debug_selector = save_debug_selector;
451
452 DEBUG(D_any)
453 debug_printf("Process %d is handling incoming connection from %s\n",
454 (int)getpid(), sender_fullhost);
455
456 /* Now disable debugging permanently if it's required only for the daemon
457 process. */
458
459 if (debug_daemon) debug_selector = 0;
460
461 /* If there are too many child processes for immediate delivery,
462 set the session_local_queue_only flag, which is initialized from the
463 configured value and may therefore already be TRUE. Leave logging
464 till later so it will have a message id attached. Note that there is no
465 possibility of re-calculating this per-message, because the value of
466 smtp_accept_count does not change in this subprocess. */
467
468 if (smtp_accept_queue > 0 && smtp_accept_count > smtp_accept_queue)
469 {
470 session_local_queue_only = TRUE;
471 queue_only_reason = 1;
472 }
473
474 /* Handle the start of the SMTP session, then loop, accepting incoming
475 messages from the SMTP connection. The end will come at the QUIT command,
476 when smtp_setup_msg() returns 0. A break in the connection causes the
477 process to die (see accept.c).
478
479 NOTE: We do *not* call smtp_log_no_mail() if smtp_start_session() fails,
480 because a log line has already been written for all its failure exists
481 (usually "connection refused: <reason>") and writing another one is
482 unnecessary clutter. */
483
484 if (!smtp_start_session())
485 {
486 mac_smtp_fflush();
487 search_tidyup();
488 _exit(EXIT_SUCCESS);
489 }
490
491 for (;;)
492 {
493 int rc;
494 message_id[0] = 0; /* Clear out any previous message_id */
495 reset_point = store_get(0); /* Save current store high water point */
496
497 DEBUG(D_any)
498 debug_printf("Process %d is ready for new message\n", (int)getpid());
499
500 /* Smtp_setup_msg() returns 0 on QUIT or if the call is from an
501 unacceptable host or if an ACL "drop" command was triggered, -1 on
502 connection lost, and +1 on validly reaching DATA. Receive_msg() almost
503 always returns TRUE when smtp_input is true; just retry if no message was
504 accepted (can happen for invalid message parameters). However, it can yield
505 FALSE if the connection was forcibly dropped by the DATA ACL. */
506
507 if ((rc = smtp_setup_msg()) > 0)
508 {
509 BOOL ok = receive_msg(FALSE);
510 search_tidyup(); /* Close cached databases */
511 if (!ok) /* Connection was dropped */
512 {
513 mac_smtp_fflush();
514 smtp_log_no_mail(); /* Log no mail if configured */
515 _exit(EXIT_SUCCESS);
516 }
517 if (message_id[0] == 0) continue; /* No message was accepted */
518 }
519 else
520 {
521 if (smtp_out)
522 {
523 int i;
524 uschar buf[128];
525
526 mac_smtp_fflush();
527 /* drain socket, for clean TCP FINs */
528 for(i = 16; read(fileno(smtp_in), buf, sizeof(buf)) > 0 && i > 0; ) i--;
529 }
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 != NULL)
545 debug_printf("Sender: %s\n", sender_address);
546 if (recipients_list != NULL)
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 store_reset(reset_point);
567
568 /* If queue_only is set or if there are too many incoming connections in
569 existence, session_local_queue_only will be TRUE. If it is not, check
570 whether we have received too many messages in this session for immediate
571 delivery. */
572
573 if (!session_local_queue_only &&
574 smtp_accept_queue_per_connection > 0 &&
575 receive_messagecount > smtp_accept_queue_per_connection)
576 {
577 session_local_queue_only = TRUE;
578 queue_only_reason = 2;
579 }
580
581 /* Initialize local_queue_only from session_local_queue_only. If it is not
582 true, and queue_only_load is set, check that the load average is below it.
583 If local_queue_only is set by this means, we also set if for the session if
584 queue_only_load_latch is true (the default). This means that, once set,
585 local_queue_only remains set for any subsequent messages on the same SMTP
586 connection. This is a deliberate choice; even though the load average may
587 fall, it doesn't seem right to deliver later messages on the same call when
588 not delivering earlier ones. However, the are special circumstances such as
589 very long-lived connections from scanning appliances where this is not the
590 best strategy. In such cases, queue_only_load_latch should be set false. */
591
592 if ( !(local_queue_only = session_local_queue_only)
593 && queue_only_load >= 0
594 && (local_queue_only = (load_average = OS_GETLOADAVG()) > queue_only_load)
595 )
596 {
597 queue_only_reason = 3;
598 if (queue_only_load_latch) session_local_queue_only = TRUE;
599 }
600
601 /* Log the queueing here, when it will get a message id attached, but
602 not if queue_only is set (case 0). */
603
604 if (local_queue_only) switch(queue_only_reason)
605 {
606 case 1: log_write(L_delay_delivery,
607 LOG_MAIN, "no immediate delivery: too many connections "
608 "(%d, max %d)", smtp_accept_count, smtp_accept_queue);
609 break;
610
611 case 2: log_write(L_delay_delivery,
612 LOG_MAIN, "no immediate delivery: more than %d messages "
613 "received in one connection", smtp_accept_queue_per_connection);
614 break;
615
616 case 3: log_write(L_delay_delivery,
617 LOG_MAIN, "no immediate delivery: load average %.2f",
618 (double)load_average/1000.0);
619 break;
620 }
621
622 /* If a delivery attempt is required, spin off a new process to handle it.
623 If we are not root, we have to re-exec exim unless deliveries are being
624 done unprivileged. */
625
626 else if (!queue_only_policy && !deliver_freeze)
627 {
628 pid_t dpid;
629
630 /* Before forking, ensure that the C output buffer is flushed. Otherwise
631 anything that it in it will get duplicated, leading to duplicate copies
632 of the pending output. */
633
634 mac_smtp_fflush();
635
636 if ((dpid = fork()) == 0)
637 {
638 (void)fclose(smtp_in);
639 (void)fclose(smtp_out);
640
641 /* Don't ever molest the parent's SSL connection, but do clean up
642 the data structures if necessary. */
643
644 #ifdef SUPPORT_TLS
645 tls_close(TRUE, FALSE);
646 #endif
647
648 /* Reset SIGHUP and SIGCHLD in the child in both cases. */
649
650 signal(SIGHUP, SIG_DFL);
651 signal(SIGCHLD, SIG_DFL);
652
653 if (geteuid() != root_uid && !deliver_drop_privilege)
654 {
655 signal(SIGALRM, SIG_DFL);
656 (void)child_exec_exim(CEE_EXEC_PANIC, FALSE, NULL, FALSE,
657 2, US"-Mc", message_id);
658 /* Control does not return here. */
659 }
660
661 /* No need to re-exec; SIGALRM remains set to the default handler */
662
663 (void)deliver_message(message_id, FALSE, FALSE);
664 search_tidyup();
665 _exit(EXIT_SUCCESS);
666 }
667
668 if (dpid > 0)
669 {
670 DEBUG(D_any) debug_printf("forked delivery process %d\n", (int)dpid);
671 }
672 else
673 log_write(0, LOG_MAIN|LOG_PANIC, "daemon: delivery process fork "
674 "failed: %s", strerror(errno));
675 }
676 }
677 }
678
679
680 /* Carrying on in the parent daemon process... Can't do much if the fork
681 failed. Otherwise, keep count of the number of accepting processes and
682 remember the pid for ticking off when the child completes. */
683
684 if (pid < 0)
685 never_error(US"daemon: accept process fork failed", US"Fork failed", errno);
686 else
687 {
688 int i;
689 for (i = 0; i < smtp_accept_max; ++i)
690 if (smtp_slots[i].pid <= 0)
691 {
692 smtp_slots[i].pid = pid;
693 if (smtp_accept_max_per_host != NULL)
694 smtp_slots[i].host_address = string_copy_malloc(sender_host_address);
695 smtp_accept_count++;
696 break;
697 }
698 DEBUG(D_any) debug_printf("%d SMTP accept process%s running\n",
699 smtp_accept_count, (smtp_accept_count == 1)? "" : "es");
700 }
701
702 /* Get here via goto in error cases */
703
704 ERROR_RETURN:
705
706 /* Close the streams associated with the socket which will also close the
707 socket fds in this process. We can't do anything if fclose() fails, but
708 logging brings it to someone's attention. However, "connection reset by peer"
709 isn't really a problem, so skip that one. On Solaris, a dropped connection can
710 manifest itself as a broken pipe, so drop that one too. If the streams don't
711 exist, something went wrong while setting things up. Make sure the socket
712 descriptors are closed, in order to drop the connection. */
713
714 if (smtp_out)
715 {
716 if (fclose(smtp_out) != 0 && errno != ECONNRESET && errno != EPIPE)
717 log_write(0, LOG_MAIN|LOG_PANIC, "daemon: fclose(smtp_out) failed: %s",
718 strerror(errno));
719 smtp_out = NULL;
720 }
721 else (void)close(accept_socket);
722
723 if (smtp_in)
724 {
725 if (fclose(smtp_in) != 0 && errno != ECONNRESET && errno != EPIPE)
726 log_write(0, LOG_MAIN|LOG_PANIC, "daemon: fclose(smtp_in) failed: %s",
727 strerror(errno));
728 smtp_in = NULL;
729 }
730 else (void)close(dup_accept_socket);
731
732 /* Release any store used in this process, including the store used for holding
733 the incoming host address and an expanded active_hostname. */
734
735 log_close_all();
736 store_reset(reset_point);
737 sender_host_address = NULL;
738 }
739
740
741
742
743 /*************************************************
744 * Check wildcard listen special cases *
745 *************************************************/
746
747 /* This function is used when binding and listening on lists of addresses and
748 ports. It tests for special cases of wildcard listening, when IPv4 and IPv6
749 sockets may interact in different ways in different operating systems. It is
750 passed an error number, the list of listening addresses, and the current
751 address. Two checks are available: for a previous wildcard IPv6 address, or for
752 a following wildcard IPv4 address, in both cases on the same port.
753
754 In practice, pairs of wildcard addresses should be adjacent in the address list
755 because they are sorted that way below.
756
757 Arguments:
758 eno the error number
759 addresses the list of addresses
760 ipa the current IP address
761 back if TRUE, check for previous wildcard IPv6 address
762 if FALSE, check for a following wildcard IPv4 address
763
764 Returns: TRUE or FALSE
765 */
766
767 static BOOL
768 check_special_case(int eno, ip_address_item *addresses, ip_address_item *ipa,
769 BOOL back)
770 {
771 ip_address_item *ipa2;
772
773 /* For the "back" case, if the failure was "address in use" for a wildcard IPv4
774 address, seek a previous IPv6 wildcard address on the same port. As it is
775 previous, it must have been successfully bound and be listening. Flag it as a
776 "6 including 4" listener. */
777
778 if (back)
779 {
780 if (eno != EADDRINUSE || ipa->address[0] != 0) return FALSE;
781 for (ipa2 = addresses; ipa2 != ipa; ipa2 = ipa2->next)
782 {
783 if (ipa2->address[1] == 0 && ipa2->port == ipa->port)
784 {
785 ipa2->v6_include_v4 = TRUE;
786 return TRUE;
787 }
788 }
789 }
790
791 /* For the "forward" case, if the current address is a wildcard IPv6 address,
792 we seek a following wildcard IPv4 address on the same port. */
793
794 else
795 {
796 if (ipa->address[0] != ':' || ipa->address[1] != 0) return FALSE;
797 for (ipa2 = ipa->next; ipa2 != NULL; ipa2 = ipa2->next)
798 if (ipa2->address[0] == 0 && ipa->port == ipa2->port) return TRUE;
799 }
800
801 return FALSE;
802 }
803
804
805
806
807 /*************************************************
808 * Handle terminating subprocesses *
809 *************************************************/
810
811 /* Handle the termination of child processes. Theoretically, this need be done
812 only when sigchld_seen is TRUE, but rumour has it that some systems lose
813 SIGCHLD signals at busy times, so to be on the safe side, this function is
814 called each time round. It shouldn't be too expensive.
815
816 Arguments: none
817 Returns: nothing
818 */
819
820 static void
821 handle_ending_processes(void)
822 {
823 int status;
824 pid_t pid;
825
826 while ((pid = waitpid(-1, &status, WNOHANG)) > 0)
827 {
828 int i;
829 DEBUG(D_any)
830 {
831 debug_printf("child %d ended: status=0x%x\n", (int)pid, status);
832 #ifdef WCOREDUMP
833 if (WIFEXITED(status))
834 debug_printf(" normal exit, %d\n", WEXITSTATUS(status));
835 else if (WIFSIGNALED(status))
836 debug_printf(" signal exit, signal %d%s\n", WTERMSIG(status),
837 WCOREDUMP(status) ? " (core dumped)" : "");
838 #endif
839 }
840
841 /* If it's a listening daemon for which we are keeping track of individual
842 subprocesses, deal with an accepting process that has terminated. */
843
844 if (smtp_slots != NULL)
845 {
846 for (i = 0; i < smtp_accept_max; i++)
847 {
848 if (smtp_slots[i].pid == pid)
849 {
850 if (smtp_slots[i].host_address != NULL)
851 store_free(smtp_slots[i].host_address);
852 smtp_slots[i] = empty_smtp_slot;
853 if (--smtp_accept_count < 0) smtp_accept_count = 0;
854 DEBUG(D_any) debug_printf("%d SMTP accept process%s now running\n",
855 smtp_accept_count, (smtp_accept_count == 1)? "" : "es");
856 break;
857 }
858 }
859 if (i < smtp_accept_max) continue; /* Found an accepting process */
860 }
861
862 /* If it wasn't an accepting process, see if it was a queue-runner
863 process that we are tracking. */
864
865 if (queue_pid_slots)
866 {
867 int max = atoi(CS expand_string(queue_run_max));
868 for (i = 0; i < max; i++)
869 if (queue_pid_slots[i] == pid)
870 {
871 queue_pid_slots[i] = 0;
872 if (--queue_run_count < 0) queue_run_count = 0;
873 DEBUG(D_any) debug_printf("%d queue-runner process%s now running\n",
874 queue_run_count, (queue_run_count == 1)? "" : "es");
875 break;
876 }
877 }
878 }
879 }
880
881
882
883 /*************************************************
884 * Exim Daemon Mainline *
885 *************************************************/
886
887 /* The daemon can do two jobs, either of which is optional:
888
889 (1) Listens for incoming SMTP calls and spawns off a sub-process to handle
890 each one. This is requested by the -bd option, with -oX specifying the SMTP
891 port on which to listen (for testing).
892
893 (2) Spawns a queue-running process every so often. This is controlled by the
894 -q option with a an interval time. (If no time is given, a single queue run
895 is done from the main function, and control doesn't get here.)
896
897 Root privilege is required in order to attach to port 25. Some systems require
898 it when calling socket() rather than bind(). To cope with all cases, we run as
899 root for both socket() and bind(). Some systems also require root in order to
900 write to the pid file directory. This function must therefore be called as root
901 if it is to work properly in all circumstances. Once the socket is bound and
902 the pid file written, root privilege is given up if there is an exim uid.
903
904 There are no arguments to this function, and it never returns. */
905
906 void
907 daemon_go(void)
908 {
909 struct passwd *pw;
910 int *listen_sockets = NULL;
911 int listen_socket_count = 0;
912 ip_address_item *addresses = NULL;
913 time_t last_connection_time = (time_t)0;
914 int local_queue_run_max = atoi(CS expand_string(queue_run_max));
915
916 /* If any debugging options are set, turn on the D_pid bit so that all
917 debugging lines get the pid added. */
918
919 DEBUG(D_any|D_v) debug_selector |= D_pid;
920
921 if (inetd_wait_mode)
922 {
923 listen_socket_count = 1;
924 listen_sockets = store_get(sizeof(int));
925 (void) close(3);
926 if (dup2(0, 3) == -1)
927 log_write(0, LOG_MAIN|LOG_PANIC_DIE,
928 "failed to dup inetd socket safely away: %s", strerror(errno));
929
930 listen_sockets[0] = 3;
931 (void) close(0);
932 (void) close(1);
933 (void) close(2);
934 exim_nullstd();
935
936 if (debug_file == stderr)
937 {
938 /* need a call to log_write before call to open debug_file, so that
939 log.c:file_path has been initialised. This is unfortunate. */
940 log_write(0, LOG_MAIN, "debugging Exim in inetd wait mode starting");
941
942 fclose(debug_file);
943 debug_file = NULL;
944 exim_nullstd(); /* re-open fd2 after we just closed it again */
945 debug_logging_activate(US"-wait", NULL);
946 }
947
948 DEBUG(D_any) debug_printf("running in inetd wait mode\n");
949
950 /* As per below, when creating sockets ourselves, we handle tcp_nodelay for
951 our own buffering; we assume though that inetd set the socket REUSEADDR. */
952
953 if (tcp_nodelay)
954 if (setsockopt(3, IPPROTO_TCP, TCP_NODELAY, US &on, sizeof(on)))
955 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "failed to set socket NODELAY: %s",
956 strerror(errno));
957 }
958
959
960 if (inetd_wait_mode || daemon_listen)
961 {
962 /* If any option requiring a load average to be available during the
963 reception of a message is set, call os_getloadavg() while we are root
964 for those OS for which this is necessary the first time it is called (in
965 order to perform an "open" on the kernel memory file). */
966
967 #ifdef LOAD_AVG_NEEDS_ROOT
968 if (queue_only_load >= 0 || smtp_load_reserve >= 0 ||
969 (deliver_queue_load_max >= 0 && deliver_drop_privilege))
970 (void)os_getloadavg();
971 #endif
972 }
973
974
975 /* Do the preparation for setting up a listener on one or more interfaces, and
976 possible on various ports. This is controlled by the combination of
977 local_interfaces (which can set IP addresses and ports) and daemon_smtp_port
978 (which is a list of default ports to use for those items in local_interfaces
979 that do not specify a port). The -oX command line option can be used to
980 override one or both of these options.
981
982 If local_interfaces is not set, the default is to listen on all interfaces.
983 When it is set, it can include "all IPvx interfaces" as an item. This is useful
984 when different ports are in use.
985
986 It turns out that listening on all interfaces is messy in an IPv6 world,
987 because several different implementation approaches have been taken. This code
988 is now supposed to work with all of them. The point of difference is whether an
989 IPv6 socket that is listening on all interfaces will receive incoming IPv4
990 calls or not. We also have to cope with the case when IPv6 libraries exist, but
991 there is no IPv6 support in the kernel.
992
993 . On Solaris, an IPv6 socket will accept IPv4 calls, and give them as mapped
994 addresses. However, if an IPv4 socket is also listening on all interfaces,
995 calls are directed to the appropriate socket.
996
997 . On (some versions of) Linux, an IPv6 socket will accept IPv4 calls, and
998 give them as mapped addresses, but an attempt also to listen on an IPv4
999 socket on all interfaces causes an error.
1000
1001 . On OpenBSD, an IPv6 socket will not accept IPv4 calls. You have to set up
1002 two sockets if you want to accept both kinds of call.
1003
1004 . FreeBSD is like OpenBSD, but it has the IPV6_V6ONLY socket option, which
1005 can be turned off, to make it behave like the versions of Linux described
1006 above.
1007
1008 . I heard a report that the USAGI IPv6 stack for Linux has implemented
1009 IPV6_V6ONLY.
1010
1011 So, what we do when IPv6 is supported is as follows:
1012
1013 (1) After it is set up, the list of interfaces is scanned for wildcard
1014 addresses. If an IPv6 and an IPv4 wildcard are both found for the same
1015 port, the list is re-arranged so that they are together, with the IPv6
1016 wildcard first.
1017
1018 (2) If the creation of a wildcard IPv6 socket fails, we just log the error and
1019 carry on if an IPv4 wildcard socket for the same port follows later in the
1020 list. This allows Exim to carry on in the case when the kernel has no IPv6
1021 support.
1022
1023 (3) Having created an IPv6 wildcard socket, we try to set IPV6_V6ONLY if that
1024 option is defined. However, if setting fails, carry on regardless (but log
1025 the incident).
1026
1027 (4) If binding or listening on an IPv6 wildcard socket fails, it is a serious
1028 error.
1029
1030 (5) If binding or listening on an IPv4 wildcard socket fails with the error
1031 EADDRINUSE, and a previous interface was an IPv6 wildcard for the same
1032 port (which must have succeeded or we wouldn't have got this far), we
1033 assume we are in the situation where just a single socket is permitted,
1034 and ignore the error.
1035
1036 Phew!
1037
1038 The preparation code decodes options and sets up the relevant data. We do this
1039 first, so that we can return non-zero if there are any syntax errors, and also
1040 write to stderr. */
1041
1042 if (daemon_listen && !inetd_wait_mode)
1043 {
1044 int *default_smtp_port;
1045 int sep;
1046 int pct = 0;
1047 uschar *s;
1048 const uschar * list;
1049 uschar *local_iface_source = US"local_interfaces";
1050 ip_address_item *ipa;
1051 ip_address_item **pipa;
1052
1053 /* If -oX was used, disable the writing of a pid file unless -oP was
1054 explicitly used to force it. Then scan the string given to -oX. Any items
1055 that contain neither a dot nor a colon are used to override daemon_smtp_port.
1056 Any other items are used to override local_interfaces. */
1057
1058 if (override_local_interfaces != NULL)
1059 {
1060 uschar *new_smtp_port = NULL;
1061 uschar *new_local_interfaces = NULL;
1062 int portsize = 0;
1063 int portptr = 0;
1064 int ifacesize = 0;
1065 int ifaceptr = 0;
1066
1067 if (override_pid_file_path == NULL) write_pid = FALSE;
1068
1069 list = override_local_interfaces;
1070 sep = 0;
1071 while ((s = string_nextinlist(&list, &sep, big_buffer, big_buffer_size)))
1072 {
1073 uschar joinstr[4];
1074 uschar **ptr;
1075 int *sizeptr;
1076 int *ptrptr;
1077
1078 if (Ustrpbrk(s, ".:") == NULL)
1079 {
1080 ptr = &new_smtp_port;
1081 sizeptr = &portsize;
1082 ptrptr = &portptr;
1083 }
1084 else
1085 {
1086 ptr = &new_local_interfaces;
1087 sizeptr = &ifacesize;
1088 ptrptr = &ifaceptr;
1089 }
1090
1091 if (*ptr == NULL)
1092 {
1093 joinstr[0] = sep;
1094 joinstr[1] = ' ';
1095 *ptr = string_catn(*ptr, sizeptr, ptrptr, US"<", 1);
1096 }
1097
1098 *ptr = string_catn(*ptr, sizeptr, ptrptr, joinstr, 2);
1099 *ptr = string_cat (*ptr, sizeptr, ptrptr, s);
1100 }
1101
1102 if (new_smtp_port != NULL)
1103 {
1104 new_smtp_port[portptr] = 0;
1105 daemon_smtp_port = new_smtp_port;
1106 DEBUG(D_any) debug_printf("daemon_smtp_port overridden by -oX:\n %s\n",
1107 daemon_smtp_port);
1108 }
1109
1110 if (new_local_interfaces != NULL)
1111 {
1112 new_local_interfaces[ifaceptr] = 0;
1113 local_interfaces = new_local_interfaces;
1114 local_iface_source = US"-oX data";
1115 DEBUG(D_any) debug_printf("local_interfaces overridden by -oX:\n %s\n",
1116 local_interfaces);
1117 }
1118 }
1119
1120 /* Create a list of default SMTP ports, to be used if local_interfaces
1121 contains entries without explict ports. First count the number of ports, then
1122 build a translated list in a vector. */
1123
1124 list = daemon_smtp_port;
1125 sep = 0;
1126 while ((s = string_nextinlist(&list, &sep, big_buffer, big_buffer_size)))
1127 pct++;
1128 default_smtp_port = store_get((pct+1) * sizeof(int));
1129 list = daemon_smtp_port;
1130 sep = 0;
1131 for (pct = 0;
1132 (s = string_nextinlist(&list, &sep, big_buffer, big_buffer_size));
1133 pct++)
1134 {
1135 if (isdigit(*s))
1136 {
1137 uschar *end;
1138 default_smtp_port[pct] = Ustrtol(s, &end, 0);
1139 if (end != s + Ustrlen(s))
1140 log_write(0, LOG_PANIC_DIE|LOG_CONFIG, "invalid SMTP port: %s", s);
1141 }
1142 else
1143 {
1144 struct servent *smtp_service = getservbyname(CS s, "tcp");
1145 if (!smtp_service)
1146 log_write(0, LOG_PANIC_DIE|LOG_CONFIG, "TCP port \"%s\" not found", s);
1147 default_smtp_port[pct] = ntohs(smtp_service->s_port);
1148 }
1149 }
1150 default_smtp_port[pct] = 0;
1151
1152 /* Check the list of TLS-on-connect ports and do name lookups if needed */
1153
1154 list = tls_in.on_connect_ports;
1155 sep = 0;
1156 while ((s = string_nextinlist(&list, &sep, big_buffer, big_buffer_size)))
1157 if (!isdigit(*s))
1158 {
1159 list = tls_in.on_connect_ports;
1160 tls_in.on_connect_ports = NULL;
1161 sep = 0;
1162 while ((s = string_nextinlist(&list, &sep, big_buffer, big_buffer_size)))
1163 {
1164 if (!isdigit(*s))
1165 {
1166 struct servent *smtp_service = getservbyname(CS s, "tcp");
1167 if (!smtp_service)
1168 log_write(0, LOG_PANIC_DIE|LOG_CONFIG, "TCP port \"%s\" not found", s);
1169 s= string_sprintf("%d", (int)ntohs(smtp_service->s_port));
1170 }
1171 tls_in.on_connect_ports = string_append_listele(tls_in.on_connect_ports,
1172 ':', s);
1173 }
1174 break;
1175 }
1176
1177 /* Create the list of local interfaces, possibly with ports included. This
1178 list may contain references to 0.0.0.0 and ::0 as wildcards. These special
1179 values are converted below. */
1180
1181 addresses = host_build_ifacelist(local_interfaces, local_iface_source);
1182
1183 /* In the list of IP addresses, convert 0.0.0.0 into an empty string, and ::0
1184 into the string ":". We use these to recognize wildcards in IPv4 and IPv6. In
1185 fact, many IP stacks recognize 0.0.0.0 and ::0 and handle them as wildcards
1186 anyway, but we need to know which are the wildcard addresses, and the shorter
1187 strings are neater.
1188
1189 In the same scan, fill in missing port numbers from the default list. When
1190 there is more than one item in the list, extra items are created. */
1191
1192 for (ipa = addresses; ipa != NULL; ipa = ipa->next)
1193 {
1194 int i;
1195
1196 if (Ustrcmp(ipa->address, "0.0.0.0") == 0) ipa->address[0] = 0;
1197 else if (Ustrcmp(ipa->address, "::0") == 0)
1198 {
1199 ipa->address[0] = ':';
1200 ipa->address[1] = 0;
1201 }
1202
1203 if (ipa->port > 0) continue;
1204
1205 if (daemon_smtp_port[0] <= 0)
1206 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "no port specified for interface "
1207 "%s and daemon_smtp_port is unset; cannot start daemon",
1208 (ipa->address[0] == 0)? US"\"all IPv4\"" :
1209 (ipa->address[1] == 0)? US"\"all IPv6\"" : ipa->address);
1210 ipa->port = default_smtp_port[0];
1211 for (i = 1; default_smtp_port[i] > 0; i++)
1212 {
1213 ip_address_item *new = store_get(sizeof(ip_address_item));
1214 memcpy(new->address, ipa->address, Ustrlen(ipa->address) + 1);
1215 new->port = default_smtp_port[i];
1216 new->next = ipa->next;
1217 ipa->next = new;
1218 ipa = new;
1219 }
1220 }
1221
1222 /* Scan the list of addresses for wildcards. If we find an IPv4 and an IPv6
1223 wildcard for the same port, ensure that (a) they are together and (b) the
1224 IPv6 address comes first. This makes handling the messy features easier, and
1225 also simplifies the construction of the "daemon started" log line. */
1226
1227 pipa = &addresses;
1228 for (ipa = addresses; ipa != NULL; pipa = &(ipa->next), ipa = ipa->next)
1229 {
1230 ip_address_item *ipa2;
1231
1232 /* Handle an IPv4 wildcard */
1233
1234 if (ipa->address[0] == 0)
1235 {
1236 for (ipa2 = ipa; ipa2->next != NULL; ipa2 = ipa2->next)
1237 {
1238 ip_address_item *ipa3 = ipa2->next;
1239 if (ipa3->address[0] == ':' &&
1240 ipa3->address[1] == 0 &&
1241 ipa3->port == ipa->port)
1242 {
1243 ipa2->next = ipa3->next;
1244 ipa3->next = ipa;
1245 *pipa = ipa3;
1246 break;
1247 }
1248 }
1249 }
1250
1251 /* Handle an IPv6 wildcard. */
1252
1253 else if (ipa->address[0] == ':' && ipa->address[1] == 0)
1254 {
1255 for (ipa2 = ipa; ipa2->next != NULL; ipa2 = ipa2->next)
1256 {
1257 ip_address_item *ipa3 = ipa2->next;
1258 if (ipa3->address[0] == 0 && ipa3->port == ipa->port)
1259 {
1260 ipa2->next = ipa3->next;
1261 ipa3->next = ipa->next;
1262 ipa->next = ipa3;
1263 ipa = ipa3;
1264 break;
1265 }
1266 }
1267 }
1268 }
1269
1270 /* Get a vector to remember all the sockets in */
1271
1272 for (ipa = addresses; ipa != NULL; ipa = ipa->next)
1273 listen_socket_count++;
1274 listen_sockets = store_get(sizeof(int) * listen_socket_count);
1275
1276 } /* daemon_listen but not inetd_wait_mode */
1277
1278 if (daemon_listen)
1279 {
1280
1281 /* Do a sanity check on the max connects value just to save us from getting
1282 a huge amount of store. */
1283
1284 if (smtp_accept_max > 4095) smtp_accept_max = 4096;
1285
1286 /* There's no point setting smtp_accept_queue unless it is less than the max
1287 connects limit. The configuration reader ensures that the max is set if the
1288 queue-only option is set. */
1289
1290 if (smtp_accept_queue > smtp_accept_max) smtp_accept_queue = 0;
1291
1292 /* Get somewhere to keep the list of SMTP accepting pids if we are keeping
1293 track of them for total number and queue/host limits. */
1294
1295 if (smtp_accept_max > 0)
1296 {
1297 int i;
1298 smtp_slots = store_get(smtp_accept_max * sizeof(smtp_slot));
1299 for (i = 0; i < smtp_accept_max; i++) smtp_slots[i] = empty_smtp_slot;
1300 }
1301 }
1302
1303 /* The variable background_daemon is always false when debugging, but
1304 can also be forced false in order to keep a non-debugging daemon in the
1305 foreground. If background_daemon is true, close all open file descriptors that
1306 we know about, but then re-open stdin, stdout, and stderr to /dev/null. Also
1307 do this for inetd_wait mode.
1308
1309 This is protection against any called functions (in libraries, or in
1310 Perl, or whatever) that think they can write to stderr (or stdout). Before this
1311 was added, it was quite likely that an SMTP connection would use one of these
1312 file descriptors, in which case writing random stuff to it caused chaos.
1313
1314 Then disconnect from the controlling terminal, Most modern Unixes seem to have
1315 setsid() for getting rid of the controlling terminal. For any OS that doesn't,
1316 setsid() can be #defined as a no-op, or as something else. */
1317
1318 if (background_daemon || inetd_wait_mode)
1319 {
1320 log_close_all(); /* Just in case anything was logged earlier */
1321 search_tidyup(); /* Just in case any were used in reading the config. */
1322 (void)close(0); /* Get rid of stdin/stdout/stderr */
1323 (void)close(1);
1324 (void)close(2);
1325 exim_nullstd(); /* Connect stdin/stdout/stderr to /dev/null */
1326 log_stderr = NULL; /* So no attempt to copy paniclog output */
1327 }
1328
1329 if (background_daemon)
1330 {
1331 /* If the parent process of this one has pid == 1, we are re-initializing the
1332 daemon as the result of a SIGHUP. In this case, there is no need to do
1333 anything, because the controlling terminal has long gone. Otherwise, fork, in
1334 case current process is a process group leader (see 'man setsid' for an
1335 explanation) before calling setsid(). */
1336
1337 if (getppid() != 1)
1338 {
1339 pid_t pid = fork();
1340 if (pid < 0) log_write(0, LOG_MAIN|LOG_PANIC_DIE,
1341 "fork() failed when starting daemon: %s", strerror(errno));
1342 if (pid > 0) exit(EXIT_SUCCESS); /* in parent process, just exit */
1343 (void)setsid(); /* release controlling terminal */
1344 }
1345 }
1346
1347 /* We are now in the disconnected, daemon process (unless debugging). Set up
1348 the listening sockets if required. */
1349
1350 if (daemon_listen && !inetd_wait_mode)
1351 {
1352 int sk;
1353 ip_address_item *ipa;
1354
1355 /* For each IP address, create a socket, bind it to the appropriate port, and
1356 start listening. See comments above about IPv6 sockets that may or may not
1357 accept IPv4 calls when listening on all interfaces. We also have to cope with
1358 the case of a system with IPv6 libraries, but no IPv6 support in the kernel.
1359 listening, provided a wildcard IPv4 socket for the same port follows. */
1360
1361 for (ipa = addresses, sk = 0; sk < listen_socket_count; ipa = ipa->next, sk++)
1362 {
1363 BOOL wildcard;
1364 ip_address_item *ipa2;
1365 int af;
1366
1367 if (Ustrchr(ipa->address, ':') != NULL)
1368 {
1369 af = AF_INET6;
1370 wildcard = ipa->address[1] == 0;
1371 }
1372 else
1373 {
1374 af = AF_INET;
1375 wildcard = ipa->address[0] == 0;
1376 }
1377
1378 if ((listen_sockets[sk] = ip_socket(SOCK_STREAM, af)) < 0)
1379 {
1380 if (check_special_case(0, addresses, ipa, FALSE))
1381 {
1382 log_write(0, LOG_MAIN, "Failed to create IPv6 socket for wildcard "
1383 "listening (%s): will use IPv4", strerror(errno));
1384 goto SKIP_SOCKET;
1385 }
1386 log_write(0, LOG_PANIC_DIE, "IPv%c socket creation failed: %s",
1387 (af == AF_INET6)? '6' : '4', strerror(errno));
1388 }
1389
1390 /* If this is an IPv6 wildcard socket, set IPV6_V6ONLY if that option is
1391 available. Just log failure (can get protocol not available, just like
1392 socket creation can). */
1393
1394 #ifdef IPV6_V6ONLY
1395 if (af == AF_INET6 && wildcard &&
1396 setsockopt(listen_sockets[sk], IPPROTO_IPV6, IPV6_V6ONLY, (char *)(&on),
1397 sizeof(on)) < 0)
1398 log_write(0, LOG_MAIN, "Setting IPV6_V6ONLY on daemon's IPv6 wildcard "
1399 "socket failed (%s): carrying on without it", strerror(errno));
1400 #endif /* IPV6_V6ONLY */
1401
1402 /* Set SO_REUSEADDR so that the daemon can be restarted while a connection
1403 is being handled. Without this, a connection will prevent reuse of the
1404 smtp port for listening. */
1405
1406 if (setsockopt(listen_sockets[sk], SOL_SOCKET, SO_REUSEADDR,
1407 (uschar *)(&on), sizeof(on)) < 0)
1408 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "setting SO_REUSEADDR on socket "
1409 "failed when starting daemon: %s", strerror(errno));
1410
1411 /* Set TCP_NODELAY; Exim does its own buffering. There is a switch to
1412 disable this because it breaks some broken clients. */
1413
1414 if (tcp_nodelay) setsockopt(listen_sockets[sk], IPPROTO_TCP, TCP_NODELAY,
1415 (uschar *)(&on), sizeof(on));
1416
1417 /* Now bind the socket to the required port; if Exim is being restarted
1418 it may not always be possible to bind immediately, even with SO_REUSEADDR
1419 set, so try 10 times, waiting between each try. After 10 failures, we give
1420 up. In an IPv6 environment, if bind () fails with the error EADDRINUSE and
1421 we are doing wildcard IPv4 listening and there was a previous IPv6 wildcard
1422 address for the same port, ignore the error on the grounds that we must be
1423 in a system where the IPv6 socket accepts both kinds of call. This is
1424 necessary for (some release of) USAGI Linux; other IP stacks fail at the
1425 listen() stage instead. */
1426
1427 for(;;)
1428 {
1429 uschar *msg, *addr;
1430 if (ip_bind(listen_sockets[sk], af, ipa->address, ipa->port) >= 0) break;
1431 if (check_special_case(errno, addresses, ipa, TRUE))
1432 {
1433 DEBUG(D_any) debug_printf("wildcard IPv4 bind() failed after IPv6 "
1434 "listen() success; EADDRINUSE ignored\n");
1435 (void)close(listen_sockets[sk]);
1436 goto SKIP_SOCKET;
1437 }
1438 msg = US strerror(errno);
1439 addr = wildcard? ((af == AF_INET6)? US"(any IPv6)" : US"(any IPv4)") :
1440 ipa->address;
1441 if (daemon_startup_retries <= 0)
1442 log_write(0, LOG_MAIN|LOG_PANIC_DIE,
1443 "socket bind() to port %d for address %s failed: %s: "
1444 "daemon abandoned", ipa->port, addr, msg);
1445 log_write(0, LOG_MAIN, "socket bind() to port %d for address %s "
1446 "failed: %s: waiting %s before trying again (%d more %s)",
1447 ipa->port, addr, msg, readconf_printtime(daemon_startup_sleep),
1448 daemon_startup_retries, (daemon_startup_retries > 1)? "tries" : "try");
1449 daemon_startup_retries--;
1450 sleep(daemon_startup_sleep);
1451 }
1452
1453 DEBUG(D_any)
1454 if (wildcard)
1455 debug_printf("listening on all interfaces (IPv%c) port %d\n",
1456 af == AF_INET6 ? '6' : '4', ipa->port);
1457 else
1458 debug_printf("listening on %s port %d\n", ipa->address, ipa->port);
1459
1460 #ifdef TCP_FASTOPEN
1461 if (setsockopt(listen_sockets[sk], IPPROTO_TCP, TCP_FASTOPEN,
1462 &smtp_connect_backlog, sizeof(smtp_connect_backlog)))
1463 DEBUG(D_any) debug_printf("setsockopt FASTOPEN: %s", strerror(errno));
1464 #endif
1465
1466 /* Start listening on the bound socket, establishing the maximum backlog of
1467 connections that is allowed. On success, continue to the next address. */
1468
1469 if (listen(listen_sockets[sk], smtp_connect_backlog) >= 0) continue;
1470
1471 /* Listening has failed. In an IPv6 environment, as for bind(), if listen()
1472 fails with the error EADDRINUSE and we are doing IPv4 wildcard listening
1473 and there was a previous successful IPv6 wildcard listen on the same port,
1474 we want to ignore the error on the grounds that we must be in a system
1475 where the IPv6 socket accepts both kinds of call. */
1476
1477 if (!check_special_case(errno, addresses, ipa, TRUE))
1478 log_write(0, LOG_PANIC_DIE, "listen() failed on interface %s: %s",
1479 wildcard
1480 ? af == AF_INET6 ? US"(any IPv6)" : US"(any IPv4)" : ipa->address,
1481 strerror(errno));
1482
1483 DEBUG(D_any) debug_printf("wildcard IPv4 listen() failed after IPv6 "
1484 "listen() success; EADDRINUSE ignored\n");
1485 (void)close(listen_sockets[sk]);
1486
1487 /* Come here if there has been a problem with the socket which we
1488 are going to ignore. We remove the address from the chain, and back up the
1489 counts. */
1490
1491 SKIP_SOCKET:
1492 sk--; /* Back up the count */
1493 listen_socket_count--; /* Reduce the total */
1494 if (ipa == addresses) addresses = ipa->next; else
1495 {
1496 for (ipa2 = addresses; ipa2->next != ipa; ipa2 = ipa2->next);
1497 ipa2->next = ipa->next;
1498 ipa = ipa2;
1499 }
1500 } /* End of bind/listen loop for each address */
1501 } /* End of setup for listening */
1502
1503
1504 /* If we are not listening, we want to write a pid file only if -oP was
1505 explicitly given. */
1506
1507 else if (override_pid_file_path == NULL) write_pid = FALSE;
1508
1509 /* Write the pid to a known file for assistance in identification, if required.
1510 We do this before giving up root privilege, because on some systems it is
1511 necessary to be root in order to write into the pid file directory. There's
1512 nothing to stop multiple daemons running, as long as no more than one listens
1513 on a given TCP/IP port on the same interface(s). However, in these
1514 circumstances it gets far too complicated to mess with pid file names
1515 automatically. Consequently, Exim 4 writes a pid file only
1516
1517 (a) When running in the test harness, or
1518 (b) When -bd is used and -oX is not used, or
1519 (c) When -oP is used to supply a path.
1520
1521 The variable daemon_write_pid is used to control this. */
1522
1523 if (running_in_test_harness || write_pid)
1524 {
1525 FILE *f;
1526
1527 if (override_pid_file_path != NULL)
1528 pid_file_path = override_pid_file_path;
1529
1530 if (pid_file_path[0] == 0)
1531 pid_file_path = string_sprintf("%s/exim-daemon.pid", spool_directory);
1532
1533 f = modefopen(pid_file_path, "wb", 0644);
1534 if (f != NULL)
1535 {
1536 (void)fprintf(f, "%d\n", (int)getpid());
1537 (void)fclose(f);
1538 DEBUG(D_any) debug_printf("pid written to %s\n", pid_file_path);
1539 }
1540 else
1541 {
1542 DEBUG(D_any)
1543 debug_printf("%s\n", string_open_failed(errno, "pid file %s",
1544 pid_file_path));
1545 }
1546 }
1547
1548 /* Set up the handler for SIGHUP, which causes a restart of the daemon. */
1549
1550 sighup_seen = FALSE;
1551 signal(SIGHUP, sighup_handler);
1552
1553 /* Give up root privilege at this point (assuming that exim_uid and exim_gid
1554 are not root). The third argument controls the running of initgroups().
1555 Normally we do this, in order to set up the groups for the Exim user. However,
1556 if we are not root at this time - some odd installations run that way - we
1557 cannot do this. */
1558
1559 exim_setugid(exim_uid, exim_gid, geteuid()==root_uid, US"running as a daemon");
1560
1561 /* Update the originator_xxx fields so that received messages as listed as
1562 coming from Exim, not whoever started the daemon. */
1563
1564 originator_uid = exim_uid;
1565 originator_gid = exim_gid;
1566 originator_login = ((pw = getpwuid(exim_uid)) != NULL)?
1567 string_copy_malloc(US pw->pw_name) : US"exim";
1568
1569 /* Get somewhere to keep the list of queue-runner pids if we are keeping track
1570 of them (and also if we are doing queue runs). */
1571
1572 if (queue_interval > 0 && local_queue_run_max > 0)
1573 {
1574 int i;
1575 queue_pid_slots = store_get(local_queue_run_max * sizeof(pid_t));
1576 for (i = 0; i < local_queue_run_max; i++) queue_pid_slots[i] = 0;
1577 }
1578
1579 /* Set up the handler for termination of child processes. */
1580
1581 sigchld_seen = FALSE;
1582 os_non_restarting_signal(SIGCHLD, main_sigchld_handler);
1583
1584 /* If we are to run the queue periodically, pretend the alarm has just gone
1585 off. This will cause the first queue-runner to get kicked off straight away. */
1586
1587 sigalrm_seen = (queue_interval > 0);
1588
1589 /* Log the start up of a daemon - at least one of listening or queue running
1590 must be set up. */
1591
1592 if (inetd_wait_mode)
1593 {
1594 uschar *p = big_buffer;
1595
1596 if (inetd_wait_timeout >= 0)
1597 sprintf(CS p, "terminating after %d seconds", inetd_wait_timeout);
1598 else
1599 sprintf(CS p, "with no wait timeout");
1600
1601 log_write(0, LOG_MAIN,
1602 "exim %s daemon started: pid=%d, launched with listening socket, %s",
1603 version_string, getpid(), big_buffer);
1604 set_process_info("daemon(%s): pre-listening socket", version_string);
1605
1606 /* set up the timeout logic */
1607 sigalrm_seen = 1;
1608 }
1609
1610 else if (daemon_listen)
1611 {
1612 int i, j;
1613 int smtp_ports = 0;
1614 int smtps_ports = 0;
1615 ip_address_item * ipa;
1616 uschar * p = big_buffer;
1617 uschar * qinfo = queue_interval > 0
1618 ? string_sprintf("-q%s", readconf_printtime(queue_interval))
1619 : US"no queue runs";
1620
1621 /* Build a list of listening addresses in big_buffer, but limit it to 10
1622 items. The style is for backwards compatibility.
1623
1624 It is now possible to have some ports listening for SMTPS (the old,
1625 deprecated protocol that starts TLS without using STARTTLS), and others
1626 listening for standard SMTP. Keep their listings separate. */
1627
1628 for (j = 0; j < 2; j++)
1629 {
1630 for (i = 0, ipa = addresses; i < 10 && ipa; i++, ipa = ipa->next)
1631 {
1632 /* First time round, look for SMTP ports; second time round, look for
1633 SMTPS ports. For the first one of each, insert leading text. */
1634
1635 if (host_is_tls_on_connect_port(ipa->port) == (j > 0))
1636 {
1637 if (j == 0)
1638 {
1639 if (smtp_ports++ == 0)
1640 {
1641 memcpy(p, "SMTP on", 8);
1642 p += 7;
1643 }
1644 }
1645 else
1646 {
1647 if (smtps_ports++ == 0)
1648 {
1649 (void)sprintf(CS p, "%sSMTPS on",
1650 smtp_ports == 0 ? "" : " and for ");
1651 while (*p) p++;
1652 }
1653 }
1654
1655 /* Now the information about the port (and sometimes interface) */
1656
1657 if (ipa->address[0] == ':' && ipa->address[1] == 0)
1658 {
1659 if (ipa->next != NULL && ipa->next->address[0] == 0 &&
1660 ipa->next->port == ipa->port)
1661 {
1662 (void)sprintf(CS p, " port %d (IPv6 and IPv4)", ipa->port);
1663 ipa = ipa->next;
1664 }
1665 else if (ipa->v6_include_v4)
1666 (void)sprintf(CS p, " port %d (IPv6 with IPv4)", ipa->port);
1667 else
1668 (void)sprintf(CS p, " port %d (IPv6)", ipa->port);
1669 }
1670 else if (ipa->address[0] == 0)
1671 (void)sprintf(CS p, " port %d (IPv4)", ipa->port);
1672 else
1673 (void)sprintf(CS p, " [%s]:%d", ipa->address, ipa->port);
1674 while (*p != 0) p++;
1675 }
1676 }
1677
1678 if (ipa)
1679 {
1680 memcpy(p, " ...", 5);
1681 p += 4;
1682 }
1683 }
1684
1685 log_write(0, LOG_MAIN,
1686 "exim %s daemon started: pid=%d, %s, listening for %s",
1687 version_string, getpid(), qinfo, big_buffer);
1688 set_process_info("daemon(%s): %s, listening for %s",
1689 version_string, qinfo, big_buffer);
1690 }
1691
1692 else
1693 {
1694 uschar * s = *queue_name
1695 ? string_sprintf("-qG%s/%s", queue_name, readconf_printtime(queue_interval))
1696 : string_sprintf("-q%s", readconf_printtime(queue_interval));
1697 log_write(0, LOG_MAIN,
1698 "exim %s daemon started: pid=%d, %s, not listening for SMTP",
1699 version_string, getpid(), s);
1700 set_process_info("daemon(%s): %s, not listening", version_string, s);
1701 }
1702
1703 /* Do any work it might be useful to amortize over our children
1704 (eg: compile regex) */
1705
1706 dns_pattern_init();
1707
1708 #ifdef WITH_CONTENT_SCAN
1709 malware_init();
1710 #endif
1711
1712 /* Close the log so it can be renamed and moved. In the few cases below where
1713 this long-running process writes to the log (always exceptional conditions), it
1714 closes the log afterwards, for the same reason. */
1715
1716 log_close_all();
1717
1718 DEBUG(D_any) debug_print_ids(US"daemon running with");
1719
1720 /* Any messages accepted via this route are going to be SMTP. */
1721
1722 smtp_input = TRUE;
1723
1724 /* Enter the never-ending loop... */
1725
1726 for (;;)
1727 {
1728 #if HAVE_IPV6
1729 struct sockaddr_in6 accepted;
1730 #else
1731 struct sockaddr_in accepted;
1732 #endif
1733
1734 EXIM_SOCKLEN_T len;
1735 pid_t pid;
1736
1737 /* This code is placed first in the loop, so that it gets obeyed at the
1738 start, before the first wait, for the queue-runner case, so that the first
1739 one can be started immediately.
1740
1741 The other option is that we have an inetd wait timeout specified to -bw. */
1742
1743 if (sigalrm_seen)
1744 {
1745 if (inetd_wait_timeout > 0)
1746 {
1747 time_t resignal_interval = inetd_wait_timeout;
1748
1749 if (last_connection_time == (time_t)0)
1750 {
1751 DEBUG(D_any)
1752 debug_printf("inetd wait timeout expired, but still not seen first message, ignoring\n");
1753 }
1754 else
1755 {
1756 time_t now = time(NULL);
1757 if (now == (time_t)-1)
1758 {
1759 DEBUG(D_any) debug_printf("failed to get time: %s\n", strerror(errno));
1760 }
1761 else
1762 {
1763 if ((now - last_connection_time) >= inetd_wait_timeout)
1764 {
1765 DEBUG(D_any)
1766 debug_printf("inetd wait timeout %d expired, ending daemon\n",
1767 inetd_wait_timeout);
1768 log_write(0, LOG_MAIN, "exim %s daemon terminating, inetd wait timeout reached.\n",
1769 version_string);
1770 exit(EXIT_SUCCESS);
1771 }
1772 else
1773 {
1774 resignal_interval -= (now - last_connection_time);
1775 }
1776 }
1777 }
1778
1779 sigalrm_seen = FALSE;
1780 alarm(resignal_interval);
1781 }
1782
1783 else
1784 {
1785 DEBUG(D_any) debug_printf("SIGALRM received\n");
1786
1787 /* Do a full queue run in a child process, if required, unless we already
1788 have enough queue runners on the go. If we are not running as root, a
1789 re-exec is required. */
1790
1791 if (queue_interval > 0 &&
1792 (local_queue_run_max <= 0 || queue_run_count < local_queue_run_max))
1793 {
1794 if ((pid = fork()) == 0)
1795 {
1796 int sk;
1797
1798 DEBUG(D_any) debug_printf("Starting queue-runner: pid %d\n",
1799 (int)getpid());
1800
1801 /* Disable debugging if it's required only for the daemon process. We
1802 leave the above message, because it ties up with the "child ended"
1803 debugging messages. */
1804
1805 if (debug_daemon) debug_selector = 0;
1806
1807 /* Close any open listening sockets in the child */
1808
1809 for (sk = 0; sk < listen_socket_count; sk++)
1810 (void)close(listen_sockets[sk]);
1811
1812 /* Reset SIGHUP and SIGCHLD in the child in both cases. */
1813
1814 signal(SIGHUP, SIG_DFL);
1815 signal(SIGCHLD, SIG_DFL);
1816
1817 /* Re-exec if privilege has been given up, unless deliver_drop_
1818 privilege is set. Reset SIGALRM before exec(). */
1819
1820 if (geteuid() != root_uid && !deliver_drop_privilege)
1821 {
1822 uschar opt[8];
1823 uschar *p = opt;
1824 uschar *extra[5];
1825 int extracount = 1;
1826
1827 signal(SIGALRM, SIG_DFL);
1828 *p++ = '-';
1829 *p++ = 'q';
1830 if (queue_2stage) *p++ = 'q';
1831 if (queue_run_first_delivery) *p++ = 'i';
1832 if (queue_run_force) *p++ = 'f';
1833 if (deliver_force_thaw) *p++ = 'f';
1834 if (queue_run_local) *p++ = 'l';
1835 *p = 0;
1836 extra[0] = queue_name
1837 ? string_sprintf("%sG%s", opt, queue_name) : opt;
1838
1839 /* If -R or -S were on the original command line, ensure they get
1840 passed on. */
1841
1842 if (deliver_selectstring)
1843 {
1844 extra[extracount++] = deliver_selectstring_regex ? US"-Rr" : US"-R";
1845 extra[extracount++] = deliver_selectstring;
1846 }
1847
1848 if (deliver_selectstring_sender)
1849 {
1850 extra[extracount++] = deliver_selectstring_sender_regex
1851 ? US"-Sr" : US"-S";
1852 extra[extracount++] = deliver_selectstring_sender;
1853 }
1854
1855 /* Overlay this process with a new execution. */
1856
1857 (void)child_exec_exim(CEE_EXEC_PANIC, FALSE, NULL, TRUE, extracount,
1858 extra[0], extra[1], extra[2], extra[3], extra[4]);
1859
1860 /* Control never returns here. */
1861 }
1862
1863 /* No need to re-exec; SIGALRM remains set to the default handler */
1864
1865 queue_run(NULL, NULL, FALSE);
1866 _exit(EXIT_SUCCESS);
1867 }
1868
1869 if (pid < 0)
1870 {
1871 log_write(0, LOG_MAIN|LOG_PANIC, "daemon: fork of queue-runner "
1872 "process failed: %s", strerror(errno));
1873 log_close_all();
1874 }
1875 else
1876 {
1877 int i;
1878 for (i = 0; i < local_queue_run_max; ++i)
1879 if (queue_pid_slots[i] <= 0)
1880 {
1881 queue_pid_slots[i] = pid;
1882 queue_run_count++;
1883 break;
1884 }
1885 DEBUG(D_any) debug_printf("%d queue-runner process%s running\n",
1886 queue_run_count, (queue_run_count == 1)? "" : "es");
1887 }
1888 }
1889
1890 /* Reset the alarm clock */
1891
1892 sigalrm_seen = FALSE;
1893 alarm(queue_interval);
1894 }
1895
1896 } /* sigalrm_seen */
1897
1898
1899 /* Sleep till a connection happens if listening, and handle the connection if
1900 that is why we woke up. The FreeBSD operating system requires the use of
1901 select() before accept() because the latter function is not interrupted by
1902 a signal, and we want to wake up for SIGCHLD and SIGALRM signals. Some other
1903 OS do notice signals in accept() but it does no harm to have the select()
1904 in for all of them - and it won't then be a lurking problem for ports to
1905 new OS. In fact, the later addition of listening on specific interfaces only
1906 requires this way of working anyway. */
1907
1908 if (daemon_listen)
1909 {
1910 int sk, lcount, select_errno;
1911 int max_socket = 0;
1912 BOOL select_failed = FALSE;
1913 fd_set select_listen;
1914
1915 FD_ZERO(&select_listen);
1916 for (sk = 0; sk < listen_socket_count; sk++)
1917 {
1918 FD_SET(listen_sockets[sk], &select_listen);
1919 if (listen_sockets[sk] > max_socket) max_socket = listen_sockets[sk];
1920 }
1921
1922 DEBUG(D_any) debug_printf("Listening...\n");
1923
1924 /* In rare cases we may have had a SIGCHLD signal in the time between
1925 setting the handler (below) and getting back here. If so, pretend that the
1926 select() was interrupted so that we reap the child. This might still leave
1927 a small window when a SIGCHLD could get lost. However, since we use SIGCHLD
1928 only to do the reaping more quickly, it shouldn't result in anything other
1929 than a delay until something else causes a wake-up. */
1930
1931 if (sigchld_seen)
1932 {
1933 lcount = -1;
1934 errno = EINTR;
1935 }
1936 else
1937 {
1938 lcount = select(max_socket + 1, (SELECT_ARG2_TYPE *)&select_listen,
1939 NULL, NULL, NULL);
1940 }
1941
1942 if (lcount < 0)
1943 {
1944 select_failed = TRUE;
1945 lcount = 1;
1946 }
1947
1948 /* Clean up any subprocesses that may have terminated. We need to do this
1949 here so that smtp_accept_max_per_host works when a connection to that host
1950 has completed, and we are about to accept a new one. When this code was
1951 later in the sequence, a new connection could be rejected, even though an
1952 old one had just finished. Preserve the errno from any select() failure for
1953 the use of the common select/accept error processing below. */
1954
1955 select_errno = errno;
1956 handle_ending_processes();
1957 errno = select_errno;
1958
1959 /* Loop for all the sockets that are currently ready to go. If select
1960 actually failed, we have set the count to 1 and select_failed=TRUE, so as
1961 to use the common error code for select/accept below. */
1962
1963 while (lcount-- > 0)
1964 {
1965 int accept_socket = -1;
1966 if (!select_failed)
1967 {
1968 for (sk = 0; sk < listen_socket_count; sk++)
1969 {
1970 if (FD_ISSET(listen_sockets[sk], &select_listen))
1971 {
1972 len = sizeof(accepted);
1973 accept_socket = accept(listen_sockets[sk],
1974 (struct sockaddr *)&accepted, &len);
1975 FD_CLR(listen_sockets[sk], &select_listen);
1976 break;
1977 }
1978 }
1979 }
1980
1981 /* If select or accept has failed and this was not caused by an
1982 interruption, log the incident and try again. With asymmetric TCP/IP
1983 routing errors such as "No route to network" have been seen here. Also
1984 "connection reset by peer" has been seen. These cannot be classed as
1985 disastrous errors, but they could fill up a lot of log. The code in smail
1986 crashes the daemon after 10 successive failures of accept, on the grounds
1987 that some OS fail continuously. Exim originally followed suit, but this
1988 appears to have caused problems. Now it just keeps going, but instead of
1989 logging each error, it batches them up when they are continuous. */
1990
1991 if (accept_socket < 0 && errno != EINTR)
1992 {
1993 if (accept_retry_count == 0)
1994 {
1995 accept_retry_errno = errno;
1996 accept_retry_select_failed = select_failed;
1997 }
1998 else
1999 {
2000 if (errno != accept_retry_errno ||
2001 select_failed != accept_retry_select_failed ||
2002 accept_retry_count >= 50)
2003 {
2004 log_write(0, LOG_MAIN | ((accept_retry_count >= 50)? LOG_PANIC : 0),
2005 "%d %s() failure%s: %s",
2006 accept_retry_count,
2007 accept_retry_select_failed? "select" : "accept",
2008 (accept_retry_count == 1)? "" : "s",
2009 strerror(accept_retry_errno));
2010 log_close_all();
2011 accept_retry_count = 0;
2012 accept_retry_errno = errno;
2013 accept_retry_select_failed = select_failed;
2014 }
2015 }
2016 accept_retry_count++;
2017 }
2018
2019 else
2020 {
2021 if (accept_retry_count > 0)
2022 {
2023 log_write(0, LOG_MAIN, "%d %s() failure%s: %s",
2024 accept_retry_count,
2025 accept_retry_select_failed? "select" : "accept",
2026 (accept_retry_count == 1)? "" : "s",
2027 strerror(accept_retry_errno));
2028 log_close_all();
2029 accept_retry_count = 0;
2030 }
2031 }
2032
2033 /* If select/accept succeeded, deal with the connection. */
2034
2035 if (accept_socket >= 0)
2036 {
2037 if (inetd_wait_timeout)
2038 last_connection_time = time(NULL);
2039 handle_smtp_call(listen_sockets, listen_socket_count, accept_socket,
2040 (struct sockaddr *)&accepted);
2041 }
2042 }
2043 }
2044
2045 /* If not listening, then just sleep for the queue interval. If we woke
2046 up early the last time for some other signal, it won't matter because
2047 the alarm signal will wake at the right time. This code originally used
2048 sleep() but it turns out that on the FreeBSD system, sleep() is not inter-
2049 rupted by signals, so it wasn't waking up for SIGALRM or SIGCHLD. Luckily
2050 select() can be used as an interruptible sleep() on all versions of Unix. */
2051
2052 else
2053 {
2054 struct timeval tv;
2055 tv.tv_sec = queue_interval;
2056 tv.tv_usec = 0;
2057 select(0, NULL, NULL, NULL, &tv);
2058 handle_ending_processes();
2059 }
2060
2061 /* Re-enable the SIGCHLD handler if it has been run. It can't do it
2062 for itself, because it isn't doing the waiting itself. */
2063
2064 if (sigchld_seen)
2065 {
2066 sigchld_seen = FALSE;
2067 os_non_restarting_signal(SIGCHLD, main_sigchld_handler);
2068 }
2069
2070 /* Handle being woken by SIGHUP. We know at this point that the result
2071 of accept() has been dealt with, so we can re-exec exim safely, first
2072 closing the listening sockets so that they can be reused. Cancel any pending
2073 alarm in case it is just about to go off, and set SIGHUP to be ignored so
2074 that another HUP in quick succession doesn't clobber the new daemon before it
2075 gets going. All log files get closed by the close-on-exec flag; however, if
2076 the exec fails, we need to close the logs. */
2077
2078 if (sighup_seen)
2079 {
2080 int sk;
2081 log_write(0, LOG_MAIN, "pid %d: SIGHUP received: re-exec daemon",
2082 getpid());
2083 for (sk = 0; sk < listen_socket_count; sk++)
2084 (void)close(listen_sockets[sk]);
2085 alarm(0);
2086 signal(SIGHUP, SIG_IGN);
2087 sighup_argv[0] = exim_path;
2088 exim_nullstd();
2089 execv(CS exim_path, (char *const *)sighup_argv);
2090 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "pid %d: exec of %s failed: %s",
2091 getpid(), exim_path, strerror(errno));
2092 log_close_all();
2093 }
2094
2095 } /* End of main loop */
2096
2097 /* Control never reaches here */
2098 }
2099
2100 /* vi: aw ai sw=2
2101 */
2102 /* End of exim_daemon.c */