1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
5 /* Copyright (c) University of Cambridge 1995 - 2018 */
6 /* Copyright (c) The Exim Maintainers 2020 */
7 /* See the file NOTICE for conditions of use and distribution. */
9 /* Functions concerned with running Exim as a daemon */
15 /* Structure for holding data for each SMTP connection */
17 typedef struct smtp_slot {
18 pid_t pid; /* pid of the spawned reception process */
19 uschar *host_address; /* address of the client host */
22 /* An empty slot for initializing (Standard C does not allow constructor
23 expressions in assignments except as initializers in declarations). */
25 static smtp_slot empty_smtp_slot = { .pid = 0, .host_address = NULL };
29 /*************************************************
30 * Local static variables *
31 *************************************************/
33 static SIGNAL_BOOL sigchld_seen;
34 static SIGNAL_BOOL sighup_seen;
35 static SIGNAL_BOOL sigterm_seen;
37 static int accept_retry_count = 0;
38 static int accept_retry_errno;
39 static BOOL accept_retry_select_failed;
41 static int queue_run_count = 0;
42 static pid_t *queue_pid_slots = NULL;
43 static smtp_slot *smtp_slots = NULL;
45 static BOOL write_pid = TRUE;
49 /*************************************************
51 *************************************************/
53 /* All this handler does is to set a flag and re-enable the signal.
55 Argument: the signal number
60 sighup_handler(int sig)
62 sig = sig; /* Keep picky compilers happy */
64 signal(SIGHUP, sighup_handler);
69 /*************************************************
70 * SIGCHLD handler for main daemon process *
71 *************************************************/
73 /* Don't re-enable the handler here, since we aren't doing the
74 waiting here. If the signal is re-enabled, there will just be an
75 infinite sequence of calls to this handler. The SIGCHLD signal is
76 used just as a means of waking up the daemon so that it notices
77 terminated subprocesses as soon as possible.
79 Argument: the signal number
84 main_sigchld_handler(int sig)
86 sig = sig; /* Keep picky compilers happy */
87 os_non_restarting_signal(SIGCHLD, SIG_DFL);
92 /* SIGTERM handler. Try to get the damon pif file removed
96 main_sigterm_handler(int sig)
104 /*************************************************
105 * Unexpected errors in SMTP calls *
106 *************************************************/
108 /* This function just saves a bit of repetitious coding.
111 log_msg Text of message to be logged
112 smtp_msg Text of SMTP error message
113 was_errno The failing errno
119 never_error(uschar *log_msg, uschar *smtp_msg, int was_errno)
121 uschar *emsg = was_errno <= 0
122 ? US"" : string_sprintf(": %s", strerror(was_errno));
123 log_write(0, LOG_MAIN|LOG_PANIC, "%s%s", log_msg, emsg);
124 if (smtp_out) smtp_printf("421 %s\r\n", FALSE, smtp_msg);
130 /*************************************************
131 *************************************************/
134 close_daemon_sockets(int daemon_notifier_fd,
135 int * listen_sockets, int listen_socket_count)
137 if (daemon_notifier_fd >= 0) (void) close(daemon_notifier_fd);
138 for (int i = 0; i < listen_socket_count; i++) (void) close(listen_sockets[i]);
142 /*************************************************
143 * Handle a connected SMTP call *
144 *************************************************/
146 /* This function is called when an SMTP connection has been accepted.
147 If there are too many, give an error message and close down. Otherwise
148 spin off a sub-process to handle the call. The list of listening sockets
149 is required so that they can be closed in the sub-process. Take care not to
150 leak store in this process - reset the stacking pool at the end.
153 listen_sockets sockets which are listening for incoming calls
154 listen_socket_count count of listening sockets
155 accept_socket socket of the current accepted call
156 accepted socket information about the current call
162 handle_smtp_call(int *listen_sockets, int listen_socket_count,
163 int accept_socket, struct sockaddr *accepted)
166 union sockaddr_46 interface_sockaddr;
167 EXIM_SOCKLEN_T ifsize = sizeof(interface_sockaddr);
168 int dup_accept_socket = -1;
169 int max_for_this_host = 0;
170 int save_log_selector = *log_selector;
173 rmark reset_point = store_mark();
175 /* Make the address available in ASCII representation, and also fish out
178 sender_host_address = host_ntoa(-1, accepted, NULL, &sender_host_port);
179 DEBUG(D_any) debug_printf("Connection request from %s port %d\n",
180 sender_host_address, sender_host_port);
182 /* Set up the output stream, check the socket has duplicated, and set up the
183 input stream. These operations fail only the exceptional circumstances. Note
184 that never_error() won't use smtp_out if it is NULL. */
186 if (!(smtp_out = fdopen(accept_socket, "wb")))
188 never_error(US"daemon: fdopen() for smtp_out failed", US"", errno);
192 if ((dup_accept_socket = dup(accept_socket)) < 0)
194 never_error(US"daemon: couldn't dup socket descriptor",
195 US"Connection setup failed", errno);
199 if (!(smtp_in = fdopen(dup_accept_socket, "rb")))
201 never_error(US"daemon: fdopen() for smtp_in failed",
202 US"Connection setup failed", errno);
206 /* Get the data for the local interface address. Panic for most errors, but
207 "connection reset by peer" just means the connection went away. */
209 if (getsockname(accept_socket, (struct sockaddr *)(&interface_sockaddr),
212 log_write(0, LOG_MAIN | ((errno == ECONNRESET)? 0 : LOG_PANIC),
213 "getsockname() failed: %s", strerror(errno));
214 smtp_printf("421 Local problem: getsockname() failed; please try again later\r\n", FALSE);
218 interface_address = host_ntoa(-1, &interface_sockaddr, NULL, &interface_port);
219 DEBUG(D_interface) debug_printf("interface address=%s port=%d\n",
220 interface_address, interface_port);
222 /* Build a string identifying the remote host and, if requested, the port and
223 the local interface data. This is for logging; at the end of this function the
224 memory is reclaimed. */
226 whofrom = string_append(NULL, 3, "[", sender_host_address, "]");
228 if (LOGGING(incoming_port))
229 whofrom = string_fmt_append(whofrom, ":%d", sender_host_port);
231 if (LOGGING(incoming_interface))
232 whofrom = string_fmt_append(whofrom, " I=[%s]:%d",
233 interface_address, interface_port);
235 (void) string_from_gstring(whofrom); /* Terminate the newly-built string */
237 /* Check maximum number of connections. We do not check for reserved
238 connections or unacceptable hosts here. That is done in the subprocess because
239 it might take some time. */
241 if (smtp_accept_max > 0 && smtp_accept_count >= smtp_accept_max)
243 DEBUG(D_any) debug_printf("rejecting SMTP connection: count=%d max=%d\n",
244 smtp_accept_count, smtp_accept_max);
245 smtp_printf("421 Too many concurrent SMTP connections; "
246 "please try again later.\r\n", FALSE);
247 log_write(L_connection_reject,
248 LOG_MAIN, "Connection from %s refused: too many connections",
253 /* If a load limit above which only reserved hosts are acceptable is defined,
254 get the load average here, and if there are in fact no reserved hosts, do
255 the test right away (saves a fork). If there are hosts, do the check in the
256 subprocess because it might take time. */
258 if (smtp_load_reserve >= 0)
260 load_average = OS_GETLOADAVG();
261 if (smtp_reserve_hosts == NULL && load_average > smtp_load_reserve)
263 DEBUG(D_any) debug_printf("rejecting SMTP connection: load average = %.2f\n",
264 (double)load_average/1000.0);
265 smtp_printf("421 Too much load; please try again later.\r\n", FALSE);
266 log_write(L_connection_reject,
267 LOG_MAIN, "Connection from %s refused: load average = %.2f",
268 whofrom->s, (double)load_average/1000.0);
273 /* Check that one specific host (strictly, IP address) is not hogging
274 resources. This is done here to prevent a denial of service attack by someone
275 forcing you to fork lots of times before denying service. The value of
276 smtp_accept_max_per_host is a string which is expanded. This makes it possible
277 to provide host-specific limits according to $sender_host address, but because
278 this is in the daemon mainline, only fast expansions (such as inline address
279 checks) should be used. The documentation is full of warnings. */
281 if (smtp_accept_max_per_host != NULL)
283 uschar *expanded = expand_string(smtp_accept_max_per_host);
284 if (expanded == NULL)
286 if (!f.expand_string_forcedfail)
287 log_write(0, LOG_MAIN|LOG_PANIC, "expansion of smtp_accept_max_per_host "
288 "failed for %s: %s", whofrom->s, expand_string_message);
290 /* For speed, interpret a decimal number inline here */
293 uschar *s = expanded;
295 max_for_this_host = max_for_this_host * 10 + *s++ - '0';
297 log_write(0, LOG_MAIN|LOG_PANIC, "expansion of smtp_accept_max_per_host "
298 "for %s contains non-digit: %s", whofrom->s, expanded);
302 /* If we have fewer connections than max_for_this_host, we can skip the tedious
303 per host_address checks. Note that at this stage smtp_accept_count contains the
304 count of *other* connections, not including this one. */
306 if ((max_for_this_host > 0) &&
307 (smtp_accept_count >= max_for_this_host))
309 int host_accept_count = 0;
310 int other_host_count = 0; /* keep a count of non matches to optimise */
312 for (int i = 0; i < smtp_accept_max; ++i)
313 if (smtp_slots[i].host_address)
315 if (Ustrcmp(sender_host_address, smtp_slots[i].host_address) == 0)
320 /* Testing all these strings is expensive - see if we can drop out
321 early, either by hitting the target, or finding there are not enough
322 connections left to make the target. */
324 if ((host_accept_count >= max_for_this_host) ||
325 ((smtp_accept_count - other_host_count) < max_for_this_host))
329 if (host_accept_count >= max_for_this_host)
331 DEBUG(D_any) debug_printf("rejecting SMTP connection: too many from this "
332 "IP address: count=%d max=%d\n",
333 host_accept_count, max_for_this_host);
334 smtp_printf("421 Too many concurrent SMTP connections "
335 "from this IP address; please try again later.\r\n", FALSE);
336 log_write(L_connection_reject,
337 LOG_MAIN, "Connection from %s refused: too many connections "
338 "from that IP address", whofrom->s);
344 /* OK, the connection count checks have been passed. Before we can fork the
345 accepting process, we must first log the connection if requested. This logging
346 used to happen in the subprocess, but doing that means that the value of
347 smtp_accept_count can be out of step by the time it is logged. So we have to do
348 the logging here and accept the performance cost. Note that smtp_accept_count
349 hasn't yet been incremented to take account of this connection.
351 In order to minimize the cost (because this is going to happen for every
352 connection), do a preliminary selector test here. This saves ploughing through
353 the generalized logging code each time when the selector is false. If the
354 selector is set, check whether the host is on the list for logging. If not,
355 arrange to unset the selector in the subprocess. */
357 if (LOGGING(smtp_connection))
359 uschar *list = hosts_connection_nolog;
360 memset(sender_host_cache, 0, sizeof(sender_host_cache));
361 if (list != NULL && verify_check_host(&list) == OK)
362 save_log_selector &= ~L_smtp_connection;
364 log_write(L_smtp_connection, LOG_MAIN, "SMTP connection from %s "
365 "(TCP/IP connection count = %d)", whofrom->s, smtp_accept_count + 1);
368 /* Now we can fork the accepting process; do a lookup tidy, just in case any
369 expansion above did a lookup. */
372 pid = exim_fork(US"daemon-accept");
374 /* Handle the child process */
378 int queue_only_reason = 0;
379 int old_pool = store_pool;
380 int save_debug_selector = debug_selector;
381 BOOL local_queue_only;
382 BOOL session_local_queue_only;
384 struct sigaction act;
387 smtp_accept_count++; /* So that it includes this process */
389 /* May have been modified for the subprocess */
391 *log_selector = save_log_selector;
393 /* Get the local interface address into permanent store */
395 store_pool = POOL_PERM;
396 interface_address = string_copy(interface_address);
397 store_pool = old_pool;
399 /* Check for a tls-on-connect port */
401 if (host_is_tls_on_connect_port(interface_port)) tls_in.on_connect = TRUE;
403 /* Expand smtp_active_hostname if required. We do not do this any earlier,
404 because it may depend on the local interface address (indeed, that is most
405 likely what it depends on.) */
407 smtp_active_hostname = primary_hostname;
408 if (raw_active_hostname)
410 uschar * nah = expand_string(raw_active_hostname);
413 if (!f.expand_string_forcedfail)
415 log_write(0, LOG_MAIN|LOG_PANIC, "failed to expand \"%s\" "
416 "(smtp_active_hostname): %s", raw_active_hostname,
417 expand_string_message);
418 smtp_printf("421 Local configuration error; "
419 "please try again later.\r\n", FALSE);
422 exim_underbar_exit(EXIT_FAILURE);
425 else if (*nah) smtp_active_hostname = nah;
428 /* Initialize the queueing flags */
431 session_local_queue_only = queue_only;
433 /* Close the listening sockets, and set the SIGCHLD handler to SIG_IGN.
434 We also attempt to set things up so that children are automatically reaped,
435 but just in case this isn't available, there's a paranoid waitpid() in the
436 loop too (except for systems where we are sure it isn't needed). See the more
437 extensive comment before the reception loop in exim.c for a fuller
438 explanation of this logic. */
440 close_daemon_sockets(daemon_notifier_fd, listen_sockets, listen_socket_count);
442 /* Set FD_CLOEXEC on the SMTP socket. We don't want any rogue child processes
443 to be able to communicate with them, under any circumstances. */
444 (void)fcntl(accept_socket, F_SETFD,
445 fcntl(accept_socket, F_GETFD) | FD_CLOEXEC);
446 (void)fcntl(dup_accept_socket, F_SETFD,
447 fcntl(dup_accept_socket, F_GETFD) | FD_CLOEXEC);
450 act.sa_handler = SIG_IGN;
451 sigemptyset(&(act.sa_mask));
452 act.sa_flags = SA_NOCLDWAIT;
453 sigaction(SIGCHLD, &act, NULL);
455 signal(SIGCHLD, SIG_IGN);
457 signal(SIGTERM, SIG_DFL);
459 /* Attempt to get an id from the sending machine via the RFC 1413
460 protocol. We do this in the sub-process in order not to hold up the
461 main process if there is any delay. Then set up the fullhost information
462 in case there is no HELO/EHLO.
464 If debugging is enabled only for the daemon, we must turn if off while
465 finding the id, but turn it on again afterwards so that information about the
466 incoming connection is output. */
468 if (f.debug_daemon) debug_selector = 0;
469 verify_get_ident(IDENT_PORT);
470 host_build_sender_fullhost();
471 debug_selector = save_debug_selector;
474 debug_printf("Process %d is handling incoming connection from %s\n",
475 (int)getpid(), sender_fullhost);
477 /* Now disable debugging permanently if it's required only for the daemon
480 if (f.debug_daemon) debug_selector = 0;
482 /* If there are too many child processes for immediate delivery,
483 set the session_local_queue_only flag, which is initialized from the
484 configured value and may therefore already be TRUE. Leave logging
485 till later so it will have a message id attached. Note that there is no
486 possibility of re-calculating this per-message, because the value of
487 smtp_accept_count does not change in this subprocess. */
489 if (smtp_accept_queue > 0 && smtp_accept_count > smtp_accept_queue)
491 session_local_queue_only = TRUE;
492 queue_only_reason = 1;
495 /* Handle the start of the SMTP session, then loop, accepting incoming
496 messages from the SMTP connection. The end will come at the QUIT command,
497 when smtp_setup_msg() returns 0. A break in the connection causes the
498 process to die (see accept.c).
500 NOTE: We do *not* call smtp_log_no_mail() if smtp_start_session() fails,
501 because a log line has already been written for all its failure exists
502 (usually "connection refused: <reason>") and writing another one is
503 unnecessary clutter. */
505 if (!smtp_start_session())
509 exim_underbar_exit(EXIT_SUCCESS);
515 message_id[0] = 0; /* Clear out any previous message_id */
516 reset_point = store_mark(); /* Save current store high water point */
519 debug_printf("Process %d is ready for new message\n", (int)getpid());
521 /* Smtp_setup_msg() returns 0 on QUIT or if the call is from an
522 unacceptable host or if an ACL "drop" command was triggered, -1 on
523 connection lost, and +1 on validly reaching DATA. Receive_msg() almost
524 always returns TRUE when smtp_input is true; just retry if no message was
525 accepted (can happen for invalid message parameters). However, it can yield
526 FALSE if the connection was forcibly dropped by the DATA ACL. */
528 if ((rc = smtp_setup_msg()) > 0)
530 BOOL ok = receive_msg(FALSE);
531 search_tidyup(); /* Close cached databases */
532 if (!ok) /* Connection was dropped */
534 cancel_cutthrough_connection(TRUE, US"receive dropped");
536 smtp_log_no_mail(); /* Log no mail if configured */
537 exim_underbar_exit(EXIT_SUCCESS);
539 if (message_id[0] == 0) continue; /* No message was accepted */
545 int fd = fileno(smtp_in);
549 /* drain socket, for clean TCP FINs */
550 if (fcntl(fd, F_SETFL, O_NONBLOCK) == 0)
551 for(int i = 16; read(fd, buf, sizeof(buf)) > 0 && i > 0; ) i--;
553 cancel_cutthrough_connection(TRUE, US"message setup dropped");
555 smtp_log_no_mail(); /* Log no mail if configured */
557 /*XXX should we pause briefly, hoping that the client will be the
558 active TCP closer hence get the TCP_WAIT endpoint? */
559 DEBUG(D_receive) debug_printf("SMTP>>(close on process exit)\n");
560 exim_underbar_exit(rc ? EXIT_FAILURE : EXIT_SUCCESS);
563 /* Show the recipients when debugging */
568 debug_printf("Sender: %s\n", sender_address);
571 debug_printf("Recipients:\n");
572 for (int i = 0; i < recipients_count; i++)
573 debug_printf(" %s\n", recipients_list[i].address);
577 /* A message has been accepted. Clean up any previous delivery processes
578 that have completed and are defunct, on systems where they don't go away
579 by themselves (see comments when setting SIG_IGN above). On such systems
580 (if any) these delivery processes hang around after termination until
581 the next message is received. */
583 #ifndef SIG_IGN_WORKS
584 while (waitpid(-1, NULL, WNOHANG) > 0);
587 /* Reclaim up the store used in accepting this message */
590 int r = receive_messagecount;
591 BOOL q = f.queue_only_policy;
592 smtp_reset(reset_point);
594 f.queue_only_policy = q;
595 receive_messagecount = r;
598 /* If queue_only is set or if there are too many incoming connections in
599 existence, session_local_queue_only will be TRUE. If it is not, check
600 whether we have received too many messages in this session for immediate
603 if (!session_local_queue_only &&
604 smtp_accept_queue_per_connection > 0 &&
605 receive_messagecount > smtp_accept_queue_per_connection)
607 session_local_queue_only = TRUE;
608 queue_only_reason = 2;
611 /* Initialize local_queue_only from session_local_queue_only. If it is not
612 true, and queue_only_load is set, check that the load average is below it.
613 If local_queue_only is set by this means, we also set if for the session if
614 queue_only_load_latch is true (the default). This means that, once set,
615 local_queue_only remains set for any subsequent messages on the same SMTP
616 connection. This is a deliberate choice; even though the load average may
617 fall, it doesn't seem right to deliver later messages on the same call when
618 not delivering earlier ones. However, the are special circumstances such as
619 very long-lived connections from scanning appliances where this is not the
620 best strategy. In such cases, queue_only_load_latch should be set false. */
622 if ( !(local_queue_only = session_local_queue_only)
623 && queue_only_load >= 0
624 && (local_queue_only = (load_average = OS_GETLOADAVG()) > queue_only_load)
627 queue_only_reason = 3;
628 if (queue_only_load_latch) session_local_queue_only = TRUE;
631 /* Log the queueing here, when it will get a message id attached, but
632 not if queue_only is set (case 0). */
634 if (local_queue_only) switch(queue_only_reason)
636 case 1: log_write(L_delay_delivery,
637 LOG_MAIN, "no immediate delivery: too many connections "
638 "(%d, max %d)", smtp_accept_count, smtp_accept_queue);
641 case 2: log_write(L_delay_delivery,
642 LOG_MAIN, "no immediate delivery: more than %d messages "
643 "received in one connection", smtp_accept_queue_per_connection);
646 case 3: log_write(L_delay_delivery,
647 LOG_MAIN, "no immediate delivery: load average %.2f",
648 (double)load_average/1000.0);
652 /* If a delivery attempt is required, spin off a new process to handle it.
653 If we are not root, we have to re-exec exim unless deliveries are being
654 done unprivileged. */
656 else if ( (!f.queue_only_policy || f.queue_smtp)
657 && !f.deliver_freeze)
661 /* Before forking, ensure that the C output buffer is flushed. Otherwise
662 anything that it in it will get duplicated, leading to duplicate copies
663 of the pending output. */
667 if ((dpid = exim_fork(US"daemon-accept-delivery")) == 0)
669 (void)fclose(smtp_in);
670 (void)fclose(smtp_out);
672 /* Don't ever molest the parent's SSL connection, but do clean up
673 the data structures if necessary. */
676 tls_close(NULL, TLS_NO_SHUTDOWN);
679 /* Reset SIGHUP and SIGCHLD in the child in both cases. */
681 signal(SIGHUP, SIG_DFL);
682 signal(SIGCHLD, SIG_DFL);
683 signal(SIGTERM, SIG_DFL);
685 if (geteuid() != root_uid && !deliver_drop_privilege)
687 signal(SIGALRM, SIG_DFL);
688 delivery_re_exec(CEE_EXEC_PANIC);
689 /* Control does not return here. */
692 /* No need to re-exec; SIGALRM remains set to the default handler */
694 (void) deliver_message(message_id, FALSE, FALSE);
696 exim_underbar_exit(EXIT_SUCCESS);
701 release_cutthrough_connection(US"passed for delivery");
702 DEBUG(D_any) debug_printf("forked delivery process %d\n", (int)dpid);
706 cancel_cutthrough_connection(TRUE, US"delivery fork failed");
707 log_write(0, LOG_MAIN|LOG_PANIC, "daemon: delivery process fork "
708 "failed: %s", strerror(errno));
715 /* Carrying on in the parent daemon process... Can't do much if the fork
716 failed. Otherwise, keep count of the number of accepting processes and
717 remember the pid for ticking off when the child completes. */
720 never_error(US"daemon: accept process fork failed", US"Fork failed", errno);
723 for (int i = 0; i < smtp_accept_max; ++i)
724 if (smtp_slots[i].pid <= 0)
726 smtp_slots[i].pid = pid;
727 /* Connection closes come asyncronously, so we cannot stack this store */
728 if (smtp_accept_max_per_host)
729 smtp_slots[i].host_address = string_copy_malloc(sender_host_address);
733 DEBUG(D_any) debug_printf("%d SMTP accept process%s running\n",
734 smtp_accept_count, smtp_accept_count == 1 ? "" : "es");
737 /* Get here via goto in error cases */
741 /* Close the streams associated with the socket which will also close the
742 socket fds in this process. We can't do anything if fclose() fails, but
743 logging brings it to someone's attention. However, "connection reset by peer"
744 isn't really a problem, so skip that one. On Solaris, a dropped connection can
745 manifest itself as a broken pipe, so drop that one too. If the streams don't
746 exist, something went wrong while setting things up. Make sure the socket
747 descriptors are closed, in order to drop the connection. */
751 if (fclose(smtp_out) != 0 && errno != ECONNRESET && errno != EPIPE)
752 log_write(0, LOG_MAIN|LOG_PANIC, "daemon: fclose(smtp_out) failed: %s",
756 else (void)close(accept_socket);
760 if (fclose(smtp_in) != 0 && errno != ECONNRESET && errno != EPIPE)
761 log_write(0, LOG_MAIN|LOG_PANIC, "daemon: fclose(smtp_in) failed: %s",
765 else (void)close(dup_accept_socket);
767 /* Release any store used in this process, including the store used for holding
768 the incoming host address and an expanded active_hostname. */
772 sender_host_address = NULL;
773 store_reset(reset_point);
774 sender_host_address = NULL;
780 /*************************************************
781 * Check wildcard listen special cases *
782 *************************************************/
784 /* This function is used when binding and listening on lists of addresses and
785 ports. It tests for special cases of wildcard listening, when IPv4 and IPv6
786 sockets may interact in different ways in different operating systems. It is
787 passed an error number, the list of listening addresses, and the current
788 address. Two checks are available: for a previous wildcard IPv6 address, or for
789 a following wildcard IPv4 address, in both cases on the same port.
791 In practice, pairs of wildcard addresses should be adjacent in the address list
792 because they are sorted that way below.
796 addresses the list of addresses
797 ipa the current IP address
798 back if TRUE, check for previous wildcard IPv6 address
799 if FALSE, check for a following wildcard IPv4 address
801 Returns: TRUE or FALSE
805 check_special_case(int eno, ip_address_item *addresses, ip_address_item *ipa,
808 ip_address_item *ipa2;
810 /* For the "back" case, if the failure was "address in use" for a wildcard IPv4
811 address, seek a previous IPv6 wildcard address on the same port. As it is
812 previous, it must have been successfully bound and be listening. Flag it as a
813 "6 including 4" listener. */
817 if (eno != EADDRINUSE || ipa->address[0] != 0) return FALSE;
818 for (ipa2 = addresses; ipa2 != ipa; ipa2 = ipa2->next)
820 if (ipa2->address[1] == 0 && ipa2->port == ipa->port)
822 ipa2->v6_include_v4 = TRUE;
828 /* For the "forward" case, if the current address is a wildcard IPv6 address,
829 we seek a following wildcard IPv4 address on the same port. */
833 if (ipa->address[0] != ':' || ipa->address[1] != 0) return FALSE;
834 for (ipa2 = ipa->next; ipa2 != NULL; ipa2 = ipa2->next)
835 if (ipa2->address[0] == 0 && ipa->port == ipa2->port) return TRUE;
844 /*************************************************
845 * Handle terminating subprocesses *
846 *************************************************/
848 /* Handle the termination of child processes. Theoretically, this need be done
849 only when sigchld_seen is TRUE, but rumour has it that some systems lose
850 SIGCHLD signals at busy times, so to be on the safe side, this function is
851 called each time round. It shouldn't be too expensive.
858 handle_ending_processes(void)
863 while ((pid = waitpid(-1, &status, WNOHANG)) > 0)
867 debug_printf("child %d ended: status=0x%x\n", (int)pid, status);
869 if (WIFEXITED(status))
870 debug_printf(" normal exit, %d\n", WEXITSTATUS(status));
871 else if (WIFSIGNALED(status))
872 debug_printf(" signal exit, signal %d%s\n", WTERMSIG(status),
873 WCOREDUMP(status) ? " (core dumped)" : "");
877 /* If it's a listening daemon for which we are keeping track of individual
878 subprocesses, deal with an accepting process that has terminated. */
883 for (i = 0; i < smtp_accept_max; i++)
884 if (smtp_slots[i].pid == pid)
886 if (smtp_slots[i].host_address)
887 store_free(smtp_slots[i].host_address);
888 smtp_slots[i] = empty_smtp_slot;
889 if (--smtp_accept_count < 0) smtp_accept_count = 0;
890 DEBUG(D_any) debug_printf("%d SMTP accept process%s now running\n",
891 smtp_accept_count, (smtp_accept_count == 1)? "" : "es");
894 if (i < smtp_accept_max) continue; /* Found an accepting process */
897 /* If it wasn't an accepting process, see if it was a queue-runner
898 process that we are tracking. */
902 int max = atoi(CS expand_string(queue_run_max));
903 for (int i = 0; i < max; i++)
904 if (queue_pid_slots[i] == pid)
906 queue_pid_slots[i] = 0;
907 if (--queue_run_count < 0) queue_run_count = 0;
908 DEBUG(D_any) debug_printf("%d queue-runner process%s now running\n",
909 queue_run_count, (queue_run_count == 1)? "" : "es");
919 set_pid_file_path(void)
921 if (override_pid_file_path)
922 pid_file_path = override_pid_file_path;
925 pid_file_path = string_sprintf("%s/exim-daemon.pid", spool_directory);
929 /* Remove the daemon's pidfile. Note: runs with root privilege,
930 as a direct child of the daemon. Does not return. */
933 delete_pid_file(void)
935 uschar * daemon_pid = string_sprintf("%d\n", (int)getppid());
939 if ((f = Ufopen(pid_file_path, "rb")))
941 if ( fgets(CS big_buffer, big_buffer_size, f)
942 && Ustrcmp(daemon_pid, big_buffer) == 0
944 if (Uunlink(pid_file_path) == 0)
947 debug_printf("%s unlink: %s\n", pid_file_path, strerror(errno));
951 debug_printf("unlinked %s\n", pid_file_path);
956 debug_printf("%s\n", string_open_failed(errno, "pid file %s",
958 exim_exit(EXIT_SUCCESS);
962 /* Called by the daemon; exec a child to get the pid file deleted
963 since we may require privs for the containing directory */
970 if (daemon_notifier_fd >= 0)
972 close(daemon_notifier_fd);
973 daemon_notifier_fd = -1;
974 #ifndef EXIM_HAVE_ABSTRACT_UNIX_SOCKETS
976 uschar * s = expand_string(notifier_socket);
977 DEBUG(D_any) debug_printf("unlinking notifier socket %s\n", s);
983 if (f.running_in_test_harness || write_pid)
985 if ((pid = exim_fork(US"daemon-del-pidfile")) == 0)
987 if (override_pid_file_path)
988 (void)child_exec_exim(CEE_EXEC_PANIC, FALSE, NULL, FALSE, 3,
989 "-oP", override_pid_file_path, "-oPX");
991 (void)child_exec_exim(CEE_EXEC_PANIC, FALSE, NULL, FALSE, 1, "-oPX");
993 /* Control never returns here. */
998 exim_exit(EXIT_SUCCESS);
1002 /*************************************************
1003 * Listener socket for local work prompts *
1004 *************************************************/
1007 daemon_notifier_socket(void)
1010 const uschar * where;
1011 struct sockaddr_un sa_un = {.sun_family = AF_UNIX};
1014 if (override_local_interfaces && !override_pid_file_path)
1017 debug_printf("-oX used without -oP so not creating notifier socket\n");
1021 DEBUG(D_any) debug_printf("creating notifier socket\n");
1024 if ((fd = socket(PF_UNIX, SOCK_DGRAM|SOCK_CLOEXEC, 0)) < 0)
1025 { where = US"socket"; goto bad; }
1027 if ((fd = socket(PF_UNIX, SOCK_DGRAM, 0)) < 0)
1028 { where = US"socket"; goto bad; }
1029 (void)fcntl(fd, F_SETFD, fcntl(fd, F_GETFD) | FD_CLOEXEC);
1032 #ifdef EXIM_HAVE_ABSTRACT_UNIX_SOCKETS
1033 sa_un.sun_path[0] = 0; /* Abstract local socket addr - Linux-specific? */
1034 len = offsetof(struct sockaddr_un, sun_path) + 1
1035 + snprintf(sa_un.sun_path+1, sizeof(sa_un.sun_path)-1, "%s",
1036 expand_string(notifier_socket));
1037 DEBUG(D_any) debug_printf(" @%s\n", sa_un.sun_path+1);
1038 #else /* filesystem-visible and persistent; will neeed removal */
1039 len = offsetof(struct sockaddr_un, sun_path)
1040 + snprintf(sa_un.sun_path, sizeof(sa_un.sun_path), "%s",
1041 expand_string(notifier_socket));
1042 DEBUG(D_any) debug_printf(" %s\n", sa_un.sun_path);
1045 if (bind(fd, (const struct sockaddr *)&sa_un, len) < 0)
1046 { where = US"bind"; goto bad; }
1048 #ifdef SO_PASSCRED /* Linux */
1049 if (setsockopt(fd, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on)) < 0)
1050 { where = US"SO_PASSCRED"; goto bad2; }
1051 #elif defined(LOCAL_CREDS) /* FreeBSD-ish */
1052 if (setsockopt(fd, 0, LOCAL_CREDS, &on, sizeof(on)) < 0)
1053 { where = US"LOCAL_CREDS"; goto bad2; }
1056 /* debug_printf("%s: fd %d\n", __FUNCTION__, fd); */
1057 daemon_notifier_fd = fd;
1061 #ifndef EXIM_HAVE_ABSTRACT_UNIX_SOCKETS
1062 Uunlink(sa_un.sun_path);
1065 log_write(0, LOG_MAIN|LOG_PANIC, "%s %s: %s",
1066 __FUNCTION__, where, strerror(errno));
1072 static uschar queuerun_msgid[MESSAGE_ID_LENGTH+1];
1074 /* Return TRUE if a sigalrm should be emulated */
1076 daemon_notification(void)
1078 uschar buf[256], cbuf[256];
1079 struct sockaddr_un sa_un;
1080 struct iovec iov = {.iov_base = buf, .iov_len = sizeof(buf)-1};
1081 struct msghdr msg = { .msg_name = &sa_un,
1082 .msg_namelen = sizeof(sa_un),
1085 .msg_control = cbuf,
1086 .msg_controllen = sizeof(cbuf)
1090 buf[sizeof(buf)-1] = 0;
1091 if ((sz = recvmsg(daemon_notifier_fd, &msg, 0)) <= 0) return FALSE;
1092 if (sz >= sizeof(buf)) return FALSE;
1095 debug_printf("addrlen %d\n", msg.msg_namelen);
1097 DEBUG(D_queue_run) debug_printf("%s from addr '%s%.*s'\n", __FUNCTION__,
1098 *sa_un.sun_path ? "" : "@",
1099 (int)msg.msg_namelen - (*sa_un.sun_path ? 0 : 1),
1100 sa_un.sun_path + (*sa_un.sun_path ? 0 : 1));
1102 /* Refuse to handle the item unless the peer has good credentials */
1103 #ifdef SCM_CREDENTIALS
1104 # define EXIM_SCM_CR_TYPE SCM_CREDENTIALS
1105 #elif defined(LOCAL_CREDS) && defined(SCM_CREDS)
1106 # define EXIM_SCM_CR_TYPE SCM_CREDS
1108 /* The OS has no way to get the creds of the caller (for a unix/datagram socket.
1109 Punt; don't try to check. */
1112 #ifdef EXIM_SCM_CR_TYPE
1113 for (struct cmsghdr * cp = CMSG_FIRSTHDR(&msg);
1115 cp = CMSG_NXTHDR(&msg, cp))
1116 if (cp->cmsg_level == SOL_SOCKET && cp->cmsg_type == EXIM_SCM_CR_TYPE)
1118 # ifdef SCM_CREDENTIALS /* Linux */
1119 struct ucred * cr = (struct ucred *) CMSG_DATA(cp);
1120 if (cr->uid && cr->uid != exim_uid)
1122 DEBUG(D_queue_run) debug_printf("%s: sender creds pid %d uid %d gid %d\n",
1123 __FUNCTION__, (int)cr->pid, (int)cr->uid, (int)cr->gid);
1126 # elif defined(LOCAL_CREDS) /* BSD-ish */
1127 struct sockcred * cr = (struct sockcred *) CMSG_DATA(cp);
1128 if (cr->sc_uid && cr->sc_uid != exim_uid)
1130 DEBUG(D_queue_run) debug_printf("%s: sender creds pid ??? uid %d gid %d\n",
1131 __FUNCTION__, (int)cr->sc_uid, (int)cr->sc_gid);
1142 #ifdef EXPERIMENTAL_QUEUE_RAMP
1143 case NOTIFY_MSG_QRUN:
1144 /* this should be a message_id */
1146 debug_printf("%s: qrunner trigger: %s\n", __FUNCTION__, buf+1);
1147 memcpy(queuerun_msgid, buf+1, MESSAGE_ID_LENGTH+1);
1149 #endif /*EXPERIMENTAL_QUEUE_RAMP*/
1151 case NOTIFY_QUEUE_SIZE_REQ:
1154 int len = snprintf(CS buf, sizeof(buf), "%u", queue_count_cached());
1157 debug_printf("%s: queue size request: %s\n", __FUNCTION__, buf);
1159 if (sendto(daemon_notifier_fd, buf, len, 0,
1160 (const struct sockaddr *)&sa_un, msg.msg_namelen) < 0)
1161 log_write(0, LOG_MAIN|LOG_PANIC,
1162 "%s: sendto: %s\n", __FUNCTION__, strerror(errno));
1170 /*************************************************
1171 * Exim Daemon Mainline *
1172 *************************************************/
1174 /* The daemon can do two jobs, either of which is optional:
1176 (1) Listens for incoming SMTP calls and spawns off a sub-process to handle
1177 each one. This is requested by the -bd option, with -oX specifying the SMTP
1178 port on which to listen (for testing).
1180 (2) Spawns a queue-running process every so often. This is controlled by the
1181 -q option with a an interval time. (If no time is given, a single queue run
1182 is done from the main function, and control doesn't get here.)
1184 Root privilege is required in order to attach to port 25. Some systems require
1185 it when calling socket() rather than bind(). To cope with all cases, we run as
1186 root for both socket() and bind(). Some systems also require root in order to
1187 write to the pid file directory. This function must therefore be called as root
1188 if it is to work properly in all circumstances. Once the socket is bound and
1189 the pid file written, root privilege is given up if there is an exim uid.
1191 There are no arguments to this function, and it never returns. */
1197 int *listen_sockets = NULL;
1198 int listen_socket_count = 0;
1199 ip_address_item *addresses = NULL;
1200 time_t last_connection_time = (time_t)0;
1201 int local_queue_run_max = atoi(CS expand_string(queue_run_max));
1203 process_purpose = US"daemon";
1205 /* If any debugging options are set, turn on the D_pid bit so that all
1206 debugging lines get the pid added. */
1208 DEBUG(D_any|D_v) debug_selector |= D_pid;
1210 if (f.inetd_wait_mode)
1212 listen_socket_count = 1;
1213 listen_sockets = store_get(sizeof(int), FALSE);
1215 if (dup2(0, 3) == -1)
1216 log_write(0, LOG_MAIN|LOG_PANIC_DIE,
1217 "failed to dup inetd socket safely away: %s", strerror(errno));
1219 listen_sockets[0] = 3;
1225 if (debug_file == stderr)
1227 /* need a call to log_write before call to open debug_file, so that
1228 log.c:file_path has been initialised. This is unfortunate. */
1229 log_write(0, LOG_MAIN, "debugging Exim in inetd wait mode starting");
1233 exim_nullstd(); /* re-open fd2 after we just closed it again */
1234 debug_logging_activate(US"-wait", NULL);
1237 DEBUG(D_any) debug_printf("running in inetd wait mode\n");
1239 /* As per below, when creating sockets ourselves, we handle tcp_nodelay for
1240 our own buffering; we assume though that inetd set the socket REUSEADDR. */
1243 if (setsockopt(3, IPPROTO_TCP, TCP_NODELAY, US &on, sizeof(on)))
1244 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "failed to set socket NODELAY: %s",
1249 if (f.inetd_wait_mode || f.daemon_listen)
1251 /* If any option requiring a load average to be available during the
1252 reception of a message is set, call os_getloadavg() while we are root
1253 for those OS for which this is necessary the first time it is called (in
1254 order to perform an "open" on the kernel memory file). */
1256 #ifdef LOAD_AVG_NEEDS_ROOT
1257 if (queue_only_load >= 0 || smtp_load_reserve >= 0 ||
1258 (deliver_queue_load_max >= 0 && deliver_drop_privilege))
1259 (void)os_getloadavg();
1264 /* Do the preparation for setting up a listener on one or more interfaces, and
1265 possible on various ports. This is controlled by the combination of
1266 local_interfaces (which can set IP addresses and ports) and daemon_smtp_port
1267 (which is a list of default ports to use for those items in local_interfaces
1268 that do not specify a port). The -oX command line option can be used to
1269 override one or both of these options.
1271 If local_interfaces is not set, the default is to listen on all interfaces.
1272 When it is set, it can include "all IPvx interfaces" as an item. This is useful
1273 when different ports are in use.
1275 It turns out that listening on all interfaces is messy in an IPv6 world,
1276 because several different implementation approaches have been taken. This code
1277 is now supposed to work with all of them. The point of difference is whether an
1278 IPv6 socket that is listening on all interfaces will receive incoming IPv4
1279 calls or not. We also have to cope with the case when IPv6 libraries exist, but
1280 there is no IPv6 support in the kernel.
1282 . On Solaris, an IPv6 socket will accept IPv4 calls, and give them as mapped
1283 addresses. However, if an IPv4 socket is also listening on all interfaces,
1284 calls are directed to the appropriate socket.
1286 . On (some versions of) Linux, an IPv6 socket will accept IPv4 calls, and
1287 give them as mapped addresses, but an attempt also to listen on an IPv4
1288 socket on all interfaces causes an error.
1290 . On OpenBSD, an IPv6 socket will not accept IPv4 calls. You have to set up
1291 two sockets if you want to accept both kinds of call.
1293 . FreeBSD is like OpenBSD, but it has the IPV6_V6ONLY socket option, which
1294 can be turned off, to make it behave like the versions of Linux described
1297 . I heard a report that the USAGI IPv6 stack for Linux has implemented
1300 So, what we do when IPv6 is supported is as follows:
1302 (1) After it is set up, the list of interfaces is scanned for wildcard
1303 addresses. If an IPv6 and an IPv4 wildcard are both found for the same
1304 port, the list is re-arranged so that they are together, with the IPv6
1307 (2) If the creation of a wildcard IPv6 socket fails, we just log the error and
1308 carry on if an IPv4 wildcard socket for the same port follows later in the
1309 list. This allows Exim to carry on in the case when the kernel has no IPv6
1312 (3) Having created an IPv6 wildcard socket, we try to set IPV6_V6ONLY if that
1313 option is defined. However, if setting fails, carry on regardless (but log
1316 (4) If binding or listening on an IPv6 wildcard socket fails, it is a serious
1319 (5) If binding or listening on an IPv4 wildcard socket fails with the error
1320 EADDRINUSE, and a previous interface was an IPv6 wildcard for the same
1321 port (which must have succeeded or we wouldn't have got this far), we
1322 assume we are in the situation where just a single socket is permitted,
1323 and ignore the error.
1327 The preparation code decodes options and sets up the relevant data. We do this
1328 first, so that we can return non-zero if there are any syntax errors, and also
1331 if (f.daemon_listen && !f.inetd_wait_mode)
1333 int *default_smtp_port;
1337 const uschar * list;
1338 uschar *local_iface_source = US"local_interfaces";
1339 ip_address_item *ipa;
1340 ip_address_item **pipa;
1342 /* If -oX was used, disable the writing of a pid file unless -oP was
1343 explicitly used to force it. Then scan the string given to -oX. Any items
1344 that contain neither a dot nor a colon are used to override daemon_smtp_port.
1345 Any other items are used to override local_interfaces. */
1347 if (override_local_interfaces)
1349 gstring * new_smtp_port = NULL;
1350 gstring * new_local_interfaces = NULL;
1352 if (!override_pid_file_path) write_pid = FALSE;
1354 list = override_local_interfaces;
1356 while ((s = string_nextinlist(&list, &sep, NULL, 0)))
1359 gstring ** gp = Ustrpbrk(s, ".:") ? &new_local_interfaces : &new_smtp_port;
1365 *gp = string_catn(*gp, US"<", 1);
1368 *gp = string_catn(*gp, joinstr, 2);
1369 *gp = string_cat (*gp, s);
1374 daemon_smtp_port = string_from_gstring(new_smtp_port);
1375 DEBUG(D_any) debug_printf("daemon_smtp_port overridden by -oX:\n %s\n",
1379 if (new_local_interfaces)
1381 local_interfaces = string_from_gstring(new_local_interfaces);
1382 local_iface_source = US"-oX data";
1383 DEBUG(D_any) debug_printf("local_interfaces overridden by -oX:\n %s\n",
1388 /* Create a list of default SMTP ports, to be used if local_interfaces
1389 contains entries without explicit ports. First count the number of ports, then
1390 build a translated list in a vector. */
1392 list = daemon_smtp_port;
1394 while ((s = string_nextinlist(&list, &sep, NULL, 0)))
1396 default_smtp_port = store_get((pct+1) * sizeof(int), FALSE);
1397 list = daemon_smtp_port;
1400 (s = string_nextinlist(&list, &sep, NULL, 0));
1406 default_smtp_port[pct] = Ustrtol(s, &end, 0);
1407 if (end != s + Ustrlen(s))
1408 log_write(0, LOG_PANIC_DIE|LOG_CONFIG, "invalid SMTP port: %s", s);
1412 struct servent *smtp_service = getservbyname(CS s, "tcp");
1414 log_write(0, LOG_PANIC_DIE|LOG_CONFIG, "TCP port \"%s\" not found", s);
1415 default_smtp_port[pct] = ntohs(smtp_service->s_port);
1418 default_smtp_port[pct] = 0;
1420 /* Check the list of TLS-on-connect ports and do name lookups if needed */
1422 list = tls_in.on_connect_ports;
1424 while ((s = string_nextinlist(&list, &sep, big_buffer, big_buffer_size)))
1429 list = tls_in.on_connect_ports;
1430 tls_in.on_connect_ports = NULL;
1432 while ((s = string_nextinlist(&list, &sep, big_buffer, big_buffer_size)))
1436 struct servent * smtp_service = getservbyname(CS s, "tcp");
1438 log_write(0, LOG_PANIC_DIE|LOG_CONFIG, "TCP port \"%s\" not found", s);
1439 s = string_sprintf("%d", (int)ntohs(smtp_service->s_port));
1441 g = string_append_listele(g, ':', s);
1444 tls_in.on_connect_ports = g->s;
1448 /* Create the list of local interfaces, possibly with ports included. This
1449 list may contain references to 0.0.0.0 and ::0 as wildcards. These special
1450 values are converted below. */
1452 addresses = host_build_ifacelist(local_interfaces, local_iface_source);
1454 /* In the list of IP addresses, convert 0.0.0.0 into an empty string, and ::0
1455 into the string ":". We use these to recognize wildcards in IPv4 and IPv6. In
1456 fact, many IP stacks recognize 0.0.0.0 and ::0 and handle them as wildcards
1457 anyway, but we need to know which are the wildcard addresses, and the shorter
1460 In the same scan, fill in missing port numbers from the default list. When
1461 there is more than one item in the list, extra items are created. */
1463 for (ipa = addresses; ipa; ipa = ipa->next)
1465 if (Ustrcmp(ipa->address, "0.0.0.0") == 0)
1466 ipa->address[0] = 0;
1467 else if (Ustrcmp(ipa->address, "::0") == 0)
1469 ipa->address[0] = ':';
1470 ipa->address[1] = 0;
1473 if (ipa->port > 0) continue;
1475 if (daemon_smtp_port[0] <= 0)
1476 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "no port specified for interface "
1477 "%s and daemon_smtp_port is unset; cannot start daemon",
1478 ipa->address[0] == 0 ? US"\"all IPv4\"" :
1479 ipa->address[1] == 0 ? US"\"all IPv6\"" : ipa->address);
1481 ipa->port = default_smtp_port[0];
1482 for (int i = 1; default_smtp_port[i] > 0; i++)
1484 ip_address_item *new = store_get(sizeof(ip_address_item), FALSE);
1486 memcpy(new->address, ipa->address, Ustrlen(ipa->address) + 1);
1487 new->port = default_smtp_port[i];
1488 new->next = ipa->next;
1494 /* Scan the list of addresses for wildcards. If we find an IPv4 and an IPv6
1495 wildcard for the same port, ensure that (a) they are together and (b) the
1496 IPv6 address comes first. This makes handling the messy features easier, and
1497 also simplifies the construction of the "daemon started" log line. */
1500 for (ipa = addresses; ipa; pipa = &ipa->next, ipa = ipa->next)
1502 ip_address_item *ipa2;
1504 /* Handle an IPv4 wildcard */
1506 if (ipa->address[0] == 0)
1507 for (ipa2 = ipa; ipa2->next; ipa2 = ipa2->next)
1509 ip_address_item *ipa3 = ipa2->next;
1510 if (ipa3->address[0] == ':' &&
1511 ipa3->address[1] == 0 &&
1512 ipa3->port == ipa->port)
1514 ipa2->next = ipa3->next;
1521 /* Handle an IPv6 wildcard. */
1523 else if (ipa->address[0] == ':' && ipa->address[1] == 0)
1524 for (ipa2 = ipa; ipa2->next; ipa2 = ipa2->next)
1526 ip_address_item *ipa3 = ipa2->next;
1527 if (ipa3->address[0] == 0 && ipa3->port == ipa->port)
1529 ipa2->next = ipa3->next;
1530 ipa3->next = ipa->next;
1538 /* Get a vector to remember all the sockets in */
1540 for (ipa = addresses; ipa; ipa = ipa->next)
1541 listen_socket_count++;
1542 listen_sockets = store_get(sizeof(int) * listen_socket_count, FALSE);
1544 } /* daemon_listen but not inetd_wait_mode */
1546 if (f.daemon_listen)
1549 /* Do a sanity check on the max connects value just to save us from getting
1550 a huge amount of store. */
1552 if (smtp_accept_max > 4095) smtp_accept_max = 4096;
1554 /* There's no point setting smtp_accept_queue unless it is less than the max
1555 connects limit. The configuration reader ensures that the max is set if the
1556 queue-only option is set. */
1558 if (smtp_accept_queue > smtp_accept_max) smtp_accept_queue = 0;
1560 /* Get somewhere to keep the list of SMTP accepting pids if we are keeping
1561 track of them for total number and queue/host limits. */
1563 if (smtp_accept_max > 0)
1565 smtp_slots = store_get(smtp_accept_max * sizeof(smtp_slot), FALSE);
1566 for (int i = 0; i < smtp_accept_max; i++) smtp_slots[i] = empty_smtp_slot;
1570 /* The variable background_daemon is always false when debugging, but
1571 can also be forced false in order to keep a non-debugging daemon in the
1572 foreground. If background_daemon is true, close all open file descriptors that
1573 we know about, but then re-open stdin, stdout, and stderr to /dev/null. Also
1574 do this for inetd_wait mode.
1576 This is protection against any called functions (in libraries, or in
1577 Perl, or whatever) that think they can write to stderr (or stdout). Before this
1578 was added, it was quite likely that an SMTP connection would use one of these
1579 file descriptors, in which case writing random stuff to it caused chaos.
1581 Then disconnect from the controlling terminal, Most modern Unixes seem to have
1582 setsid() for getting rid of the controlling terminal. For any OS that doesn't,
1583 setsid() can be #defined as a no-op, or as something else. */
1585 if (f.background_daemon || f.inetd_wait_mode)
1587 log_close_all(); /* Just in case anything was logged earlier */
1588 search_tidyup(); /* Just in case any were used in reading the config. */
1589 (void)close(0); /* Get rid of stdin/stdout/stderr */
1592 exim_nullstd(); /* Connect stdin/stdout/stderr to /dev/null */
1593 log_stderr = NULL; /* So no attempt to copy paniclog output */
1596 if (f.background_daemon)
1598 /* If the parent process of this one has pid == 1, we are re-initializing the
1599 daemon as the result of a SIGHUP. In this case, there is no need to do
1600 anything, because the controlling terminal has long gone. Otherwise, fork, in
1601 case current process is a process group leader (see 'man setsid' for an
1602 explanation) before calling setsid(). */
1606 pid_t pid = exim_fork(US"daemon");
1607 if (pid < 0) log_write(0, LOG_MAIN|LOG_PANIC_DIE,
1608 "fork() failed when starting daemon: %s", strerror(errno));
1609 if (pid > 0) exit(EXIT_SUCCESS); /* in parent process, just exit */
1610 (void)setsid(); /* release controlling terminal */
1614 /* We are now in the disconnected, daemon process (unless debugging). Set up
1615 the listening sockets if required. */
1617 daemon_notifier_socket();
1619 if (f.daemon_listen && !f.inetd_wait_mode)
1622 ip_address_item *ipa;
1624 /* For each IP address, create a socket, bind it to the appropriate port, and
1625 start listening. See comments above about IPv6 sockets that may or may not
1626 accept IPv4 calls when listening on all interfaces. We also have to cope with
1627 the case of a system with IPv6 libraries, but no IPv6 support in the kernel.
1628 listening, provided a wildcard IPv4 socket for the same port follows. */
1630 for (ipa = addresses, sk = 0; sk < listen_socket_count; ipa = ipa->next, sk++)
1633 ip_address_item *ipa2;
1636 if (Ustrchr(ipa->address, ':') != NULL)
1639 wildcard = ipa->address[1] == 0;
1644 wildcard = ipa->address[0] == 0;
1647 if ((listen_sockets[sk] = ip_socket(SOCK_STREAM, af)) < 0)
1649 if (check_special_case(0, addresses, ipa, FALSE))
1651 log_write(0, LOG_MAIN, "Failed to create IPv6 socket for wildcard "
1652 "listening (%s): will use IPv4", strerror(errno));
1655 log_write(0, LOG_PANIC_DIE, "IPv%c socket creation failed: %s",
1656 (af == AF_INET6)? '6' : '4', strerror(errno));
1659 /* If this is an IPv6 wildcard socket, set IPV6_V6ONLY if that option is
1660 available. Just log failure (can get protocol not available, just like
1661 socket creation can). */
1664 if (af == AF_INET6 && wildcard &&
1665 setsockopt(listen_sockets[sk], IPPROTO_IPV6, IPV6_V6ONLY, CS (&on),
1667 log_write(0, LOG_MAIN, "Setting IPV6_V6ONLY on daemon's IPv6 wildcard "
1668 "socket failed (%s): carrying on without it", strerror(errno));
1669 #endif /* IPV6_V6ONLY */
1671 /* Set SO_REUSEADDR so that the daemon can be restarted while a connection
1672 is being handled. Without this, a connection will prevent reuse of the
1673 smtp port for listening. */
1675 if (setsockopt(listen_sockets[sk], SOL_SOCKET, SO_REUSEADDR,
1676 US (&on), sizeof(on)) < 0)
1677 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "setting SO_REUSEADDR on socket "
1678 "failed when starting daemon: %s", strerror(errno));
1680 /* Set TCP_NODELAY; Exim does its own buffering. There is a switch to
1681 disable this because it breaks some broken clients. */
1683 if (tcp_nodelay) setsockopt(listen_sockets[sk], IPPROTO_TCP, TCP_NODELAY,
1684 US (&on), sizeof(on));
1686 /* Now bind the socket to the required port; if Exim is being restarted
1687 it may not always be possible to bind immediately, even with SO_REUSEADDR
1688 set, so try 10 times, waiting between each try. After 10 failures, we give
1689 up. In an IPv6 environment, if bind () fails with the error EADDRINUSE and
1690 we are doing wildcard IPv4 listening and there was a previous IPv6 wildcard
1691 address for the same port, ignore the error on the grounds that we must be
1692 in a system where the IPv6 socket accepts both kinds of call. This is
1693 necessary for (some release of) USAGI Linux; other IP stacks fail at the
1694 listen() stage instead. */
1697 f.tcp_fastopen_ok = TRUE;
1702 if (ip_bind(listen_sockets[sk], af, ipa->address, ipa->port) >= 0) break;
1703 if (check_special_case(errno, addresses, ipa, TRUE))
1705 DEBUG(D_any) debug_printf("wildcard IPv4 bind() failed after IPv6 "
1706 "listen() success; EADDRINUSE ignored\n");
1707 (void)close(listen_sockets[sk]);
1710 msg = US strerror(errno);
1716 if (daemon_startup_retries <= 0)
1717 log_write(0, LOG_MAIN|LOG_PANIC_DIE,
1718 "socket bind() to port %d for address %s failed: %s: "
1719 "daemon abandoned", ipa->port, addr, msg);
1720 log_write(0, LOG_MAIN, "socket bind() to port %d for address %s "
1721 "failed: %s: waiting %s before trying again (%d more %s)",
1722 ipa->port, addr, msg, readconf_printtime(daemon_startup_sleep),
1723 daemon_startup_retries, (daemon_startup_retries > 1)? "tries" : "try");
1724 daemon_startup_retries--;
1725 sleep(daemon_startup_sleep);
1730 debug_printf("listening on all interfaces (IPv%c) port %d\n",
1731 af == AF_INET6 ? '6' : '4', ipa->port);
1733 debug_printf("listening on %s port %d\n", ipa->address, ipa->port);
1735 #if defined(TCP_FASTOPEN) && !defined(__APPLE__)
1736 if ( f.tcp_fastopen_ok
1737 && setsockopt(listen_sockets[sk], IPPROTO_TCP, TCP_FASTOPEN,
1738 &smtp_connect_backlog, sizeof(smtp_connect_backlog)))
1740 DEBUG(D_any) debug_printf("setsockopt FASTOPEN: %s\n", strerror(errno));
1741 f.tcp_fastopen_ok = FALSE;
1745 /* Start listening on the bound socket, establishing the maximum backlog of
1746 connections that is allowed. On success, continue to the next address. */
1748 if (listen(listen_sockets[sk], smtp_connect_backlog) >= 0)
1750 #if defined(TCP_FASTOPEN) && defined(__APPLE__)
1751 if ( f.tcp_fastopen_ok
1752 && setsockopt(listen_sockets[sk], IPPROTO_TCP, TCP_FASTOPEN,
1755 DEBUG(D_any) debug_printf("setsockopt FASTOPEN: %s\n", strerror(errno));
1756 f.tcp_fastopen_ok = FALSE;
1762 /* Listening has failed. In an IPv6 environment, as for bind(), if listen()
1763 fails with the error EADDRINUSE and we are doing IPv4 wildcard listening
1764 and there was a previous successful IPv6 wildcard listen on the same port,
1765 we want to ignore the error on the grounds that we must be in a system
1766 where the IPv6 socket accepts both kinds of call. */
1768 if (!check_special_case(errno, addresses, ipa, TRUE))
1769 log_write(0, LOG_PANIC_DIE, "listen() failed on interface %s: %s",
1771 ? af == AF_INET6 ? US"(any IPv6)" : US"(any IPv4)" : ipa->address,
1774 DEBUG(D_any) debug_printf("wildcard IPv4 listen() failed after IPv6 "
1775 "listen() success; EADDRINUSE ignored\n");
1776 (void)close(listen_sockets[sk]);
1778 /* Come here if there has been a problem with the socket which we
1779 are going to ignore. We remove the address from the chain, and back up the
1783 sk--; /* Back up the count */
1784 listen_socket_count--; /* Reduce the total */
1785 if (ipa == addresses) addresses = ipa->next; else
1787 for (ipa2 = addresses; ipa2->next != ipa; ipa2 = ipa2->next);
1788 ipa2->next = ipa->next;
1791 } /* End of bind/listen loop for each address */
1792 } /* End of setup for listening */
1795 /* If we are not listening, we want to write a pid file only if -oP was
1796 explicitly given. */
1798 else if (!override_pid_file_path)
1801 /* Write the pid to a known file for assistance in identification, if required.
1802 We do this before giving up root privilege, because on some systems it is
1803 necessary to be root in order to write into the pid file directory. There's
1804 nothing to stop multiple daemons running, as long as no more than one listens
1805 on a given TCP/IP port on the same interface(s). However, in these
1806 circumstances it gets far too complicated to mess with pid file names
1807 automatically. Consequently, Exim 4 writes a pid file only
1809 (a) When running in the test harness, or
1810 (b) When -bd is used and -oX is not used, or
1811 (c) When -oP is used to supply a path.
1813 The variable daemon_write_pid is used to control this. */
1815 if (f.running_in_test_harness || write_pid)
1819 set_pid_file_path();
1820 if ((f = modefopen(pid_file_path, "wb", 0644)))
1822 (void)fprintf(f, "%d\n", (int)getpid());
1824 DEBUG(D_any) debug_printf("pid written to %s\n", pid_file_path);
1828 debug_printf("%s\n", string_open_failed(errno, "pid file %s",
1832 /* Set up the handler for SIGHUP, which causes a restart of the daemon. */
1834 sighup_seen = FALSE;
1835 signal(SIGHUP, sighup_handler);
1837 /* Give up root privilege at this point (assuming that exim_uid and exim_gid
1838 are not root). The third argument controls the running of initgroups().
1839 Normally we do this, in order to set up the groups for the Exim user. However,
1840 if we are not root at this time - some odd installations run that way - we
1843 exim_setugid(exim_uid, exim_gid, geteuid()==root_uid, US"running as a daemon");
1845 /* Update the originator_xxx fields so that received messages as listed as
1846 coming from Exim, not whoever started the daemon. */
1848 originator_uid = exim_uid;
1849 originator_gid = exim_gid;
1850 originator_login = (pw = getpwuid(exim_uid))
1851 ? string_copy_perm(US pw->pw_name, FALSE) : US"exim";
1853 /* Get somewhere to keep the list of queue-runner pids if we are keeping track
1854 of them (and also if we are doing queue runs). */
1856 if (queue_interval > 0 && local_queue_run_max > 0)
1858 queue_pid_slots = store_get(local_queue_run_max * sizeof(pid_t), FALSE);
1859 for (int i = 0; i < local_queue_run_max; i++) queue_pid_slots[i] = 0;
1862 /* Set up the handler for termination of child processes, and the one
1863 telling us to die. */
1865 sigchld_seen = FALSE;
1866 os_non_restarting_signal(SIGCHLD, main_sigchld_handler);
1868 sigterm_seen = FALSE;
1869 os_non_restarting_signal(SIGTERM, main_sigterm_handler);
1871 /* If we are to run the queue periodically, pretend the alarm has just gone
1872 off. This will cause the first queue-runner to get kicked off straight away. */
1874 sigalrm_seen = (queue_interval > 0);
1876 /* Log the start up of a daemon - at least one of listening or queue running
1879 if (f.inetd_wait_mode)
1881 uschar *p = big_buffer;
1883 if (inetd_wait_timeout >= 0)
1884 sprintf(CS p, "terminating after %d seconds", inetd_wait_timeout);
1886 sprintf(CS p, "with no wait timeout");
1888 log_write(0, LOG_MAIN,
1889 "exim %s daemon started: pid=%d, launched with listening socket, %s",
1890 version_string, getpid(), big_buffer);
1891 set_process_info("daemon(%s): pre-listening socket", version_string);
1893 /* set up the timeout logic */
1894 sigalrm_seen = TRUE;
1897 else if (f.daemon_listen)
1900 int smtps_ports = 0;
1901 ip_address_item * ipa;
1903 uschar * qinfo = queue_interval > 0
1904 ? string_sprintf("-q%s%s",
1905 f.queue_2stage ? "q" : "", readconf_printtime(queue_interval))
1906 : US"no queue runs";
1908 /* Build a list of listening addresses in big_buffer, but limit it to 10
1909 items. The style is for backwards compatibility.
1911 It is now possible to have some ports listening for SMTPS (the old,
1912 deprecated protocol that starts TLS without using STARTTLS), and others
1913 listening for standard SMTP. Keep their listings separate. */
1915 for (int j = 0, i; j < 2; j++)
1917 for (i = 0, ipa = addresses; i < 10 && ipa; i++, ipa = ipa->next)
1919 /* First time round, look for SMTP ports; second time round, look for
1920 SMTPS ports. Build IP+port strings. */
1922 if (host_is_tls_on_connect_port(ipa->port) == (j > 0))
1929 /* Now the information about the port (and sometimes interface) */
1931 if (ipa->address[0] == ':' && ipa->address[1] == 0)
1933 if (ipa->next && ipa->next->address[0] == 0 &&
1934 ipa->next->port == ipa->port)
1936 ipa->log = string_sprintf(" port %d (IPv6 and IPv4)", ipa->port);
1937 (ipa = ipa->next)->log = NULL;
1939 else if (ipa->v6_include_v4)
1940 ipa->log = string_sprintf(" port %d (IPv6 with IPv4)", ipa->port);
1942 ipa->log = string_sprintf(" port %d (IPv6)", ipa->port);
1944 else if (ipa->address[0] == 0) /* v4 wildcard */
1945 ipa->log = string_sprintf(" port %d (IPv4)", ipa->port);
1946 else /* check for previously-seen IP */
1948 ip_address_item * i2;
1949 for (i2 = addresses; i2 != ipa; i2 = i2->next)
1950 if ( host_is_tls_on_connect_port(i2->port) == (j > 0)
1951 && Ustrcmp(ipa->address, i2->address) == 0
1953 { /* found; append port to list */
1954 for (p = i2->log; *p; ) p++; /* end of existing string */
1955 if (*--p == '}') *p = '\0'; /* drop EOL */
1956 while (isdigit(*--p)) ; /* char before port */
1958 i2->log = *p == ':' /* no list yet? */
1959 ? string_sprintf("%.*s{%s,%d}",
1960 (int)(p - i2->log + 1), i2->log, p+1, ipa->port)
1961 : string_sprintf("%s,%d}", i2->log, ipa->port);
1965 if (i2 == ipa) /* first-time IP */
1966 ipa->log = string_sprintf(" [%s]:%d", ipa->address, ipa->port);
1973 for (int j = 0, i; j < 2; j++)
1975 /* First time round, look for SMTP ports; second time round, look for
1976 SMTPS ports. For the first one of each, insert leading text. */
1981 p += sprintf(CS p, "SMTP on");
1984 if (smtps_ports > 0)
1985 p += sprintf(CS p, "%sSMTPS on",
1986 smtp_ports == 0 ? "" : " and for ");
1988 /* Now the information about the port (and sometimes interface) */
1990 for (i = 0, ipa = addresses; i < 10 && ipa; i++, ipa = ipa->next)
1991 if (host_is_tls_on_connect_port(ipa->port) == (j > 0))
1993 p += sprintf(CS p, "%s", ipa->log);
1996 p += sprintf(CS p, " ...");
1999 log_write(0, LOG_MAIN,
2000 "exim %s daemon started: pid=%d, %s, listening for %s",
2001 version_string, getpid(), qinfo, big_buffer);
2002 set_process_info("daemon(%s): %s, listening for %s",
2003 version_string, qinfo, big_buffer);
2008 uschar * s = *queue_name
2009 ? string_sprintf("-qG%s/%s", queue_name, readconf_printtime(queue_interval))
2010 : string_sprintf("-q%s", readconf_printtime(queue_interval));
2011 log_write(0, LOG_MAIN,
2012 "exim %s daemon started: pid=%d, %s, not listening for SMTP",
2013 version_string, getpid(), s);
2014 set_process_info("daemon(%s): %s, not listening", version_string, s);
2017 /* Do any work it might be useful to amortize over our children
2018 (eg: compile regex) */
2021 smtp_deliver_init(); /* Used for callouts */
2023 #ifndef DISABLE_DKIM
2025 # ifdef MEASURE_TIMING
2027 gettimeofday(&t0, NULL);
2030 # ifdef MEASURE_TIMING
2031 report_time_since(&t0, US"dkim_exim_init (delta)");
2036 #ifdef WITH_CONTENT_SCAN
2043 /* Close the log so it can be renamed and moved. In the few cases below where
2044 this long-running process writes to the log (always exceptional conditions), it
2045 closes the log afterwards, for the same reason. */
2049 DEBUG(D_any) debug_print_ids(US"daemon running with");
2051 /* Any messages accepted via this route are going to be SMTP. */
2055 #ifdef MEASURE_TIMING
2056 report_time_since(×tamp_startup, US"daemon loop start"); /* testcase 0022 */
2059 /* Enter the never-ending loop... */
2064 struct sockaddr_in6 accepted;
2066 struct sockaddr_in accepted;
2073 daemon_die(); /* Does not return */
2075 /* This code is placed first in the loop, so that it gets obeyed at the
2076 start, before the first wait, for the queue-runner case, so that the first
2077 one can be started immediately.
2079 The other option is that we have an inetd wait timeout specified to -bw. */
2083 if (inetd_wait_timeout > 0)
2085 time_t resignal_interval = inetd_wait_timeout;
2087 if (last_connection_time == (time_t)0)
2090 debug_printf("inetd wait timeout expired, but still not seen first message, ignoring\n");
2094 time_t now = time(NULL);
2095 if (now == (time_t)-1)
2097 DEBUG(D_any) debug_printf("failed to get time: %s\n", strerror(errno));
2101 if ((now - last_connection_time) >= inetd_wait_timeout)
2104 debug_printf("inetd wait timeout %d expired, ending daemon\n",
2105 inetd_wait_timeout);
2106 log_write(0, LOG_MAIN, "exim %s daemon terminating, inetd wait timeout reached.\n",
2112 resignal_interval -= (now - last_connection_time);
2117 sigalrm_seen = FALSE;
2118 ALARM(resignal_interval);
2123 DEBUG(D_any) debug_printf("%s received\n",
2124 #ifdef EXPERIMENTAL_QUEUE_RAMP
2125 *queuerun_msgid ? "qrun notification" :
2129 /* Do a full queue run in a child process, if required, unless we already
2130 have enough queue runners on the go. If we are not running as root, a
2131 re-exec is required. */
2133 if ( queue_interval > 0
2134 && (local_queue_run_max <= 0 || queue_run_count < local_queue_run_max))
2136 if ((pid = exim_fork(US"queue-runner")) == 0)
2138 /* Disable debugging if it's required only for the daemon process. We
2139 leave the above message, because it ties up with the "child ended"
2140 debugging messages. */
2142 if (f.debug_daemon) debug_selector = 0;
2144 /* Close any open listening sockets in the child */
2146 close_daemon_sockets(daemon_notifier_fd,
2147 listen_sockets, listen_socket_count);
2149 /* Reset SIGHUP and SIGCHLD in the child in both cases. */
2151 signal(SIGHUP, SIG_DFL);
2152 signal(SIGCHLD, SIG_DFL);
2153 signal(SIGTERM, SIG_DFL);
2155 /* Re-exec if privilege has been given up, unless deliver_drop_
2156 privilege is set. Reset SIGALRM before exec(). */
2158 if (geteuid() != root_uid && !deliver_drop_privilege)
2165 signal(SIGALRM, SIG_DFL);
2169 #ifdef EXPERIMENTAL_QUEUE_RAMP
2173 if (f.queue_run_first_delivery) *p++ = 'i';
2174 if (f.queue_run_force) *p++ = 'f';
2175 if (f.deliver_force_thaw) *p++ = 'f';
2176 if (f.queue_run_local) *p++ = 'l';
2178 extra[0] = *queue_name
2179 ? string_sprintf("%sG%s", opt, queue_name) : opt;
2181 #ifdef EXPERIMENTAL_QUEUE_RAMP
2182 if (*queuerun_msgid)
2184 log_write(0, LOG_MAIN, "notify triggered queue run");
2185 extra[extracount++] = queuerun_msgid; /* Trigger only the */
2186 extra[extracount++] = queuerun_msgid; /* one message */
2190 /* If -R or -S were on the original command line, ensure they get
2193 if (deliver_selectstring)
2195 extra[extracount++] = f.deliver_selectstring_regex ? US"-Rr" : US"-R";
2196 extra[extracount++] = deliver_selectstring;
2199 if (deliver_selectstring_sender)
2201 extra[extracount++] = f.deliver_selectstring_sender_regex
2203 extra[extracount++] = deliver_selectstring_sender;
2206 /* Overlay this process with a new execution. */
2208 (void)child_exec_exim(CEE_EXEC_PANIC, FALSE, NULL, FALSE, extracount,
2209 extra[0], extra[1], extra[2], extra[3], extra[4], extra[5], extra[6]);
2211 /* Control never returns here. */
2214 /* No need to re-exec; SIGALRM remains set to the default handler */
2216 #ifdef EXPERIMENTAL_QUEUE_RAMP
2217 if (*queuerun_msgid)
2219 log_write(0, LOG_MAIN, "notify triggered queue run");
2220 f.queue_2stage = FALSE;
2221 queue_run(queuerun_msgid, queuerun_msgid, FALSE);
2225 queue_run(NULL, NULL, FALSE);
2226 exim_underbar_exit(EXIT_SUCCESS);
2231 log_write(0, LOG_MAIN|LOG_PANIC, "daemon: fork of queue-runner "
2232 "process failed: %s", strerror(errno));
2237 for (int i = 0; i < local_queue_run_max; ++i)
2238 if (queue_pid_slots[i] <= 0)
2240 queue_pid_slots[i] = pid;
2244 DEBUG(D_any) debug_printf("%d queue-runner process%s running\n",
2245 queue_run_count, queue_run_count == 1 ? "" : "es");
2249 /* Reset the alarm clock */
2251 sigalrm_seen = FALSE;
2252 #ifdef EXPERIMENTAL_QUEUE_RAMP
2253 if (*queuerun_msgid)
2254 *queuerun_msgid = 0;
2257 ALARM(queue_interval);
2260 } /* sigalrm_seen */
2263 /* Sleep till a connection happens if listening, and handle the connection if
2264 that is why we woke up. The FreeBSD operating system requires the use of
2265 select() before accept() because the latter function is not interrupted by
2266 a signal, and we want to wake up for SIGCHLD and SIGALRM signals. Some other
2267 OS do notice signals in accept() but it does no harm to have the select()
2268 in for all of them - and it won't then be a lurking problem for ports to
2269 new OS. In fact, the later addition of listening on specific interfaces only
2270 requires this way of working anyway. */
2272 if (f.daemon_listen)
2274 int lcount, select_errno;
2276 BOOL select_failed = FALSE;
2277 fd_set select_listen;
2279 FD_ZERO(&select_listen);
2280 if (daemon_notifier_fd >= 0)
2281 FD_SET(daemon_notifier_fd, &select_listen);
2282 for (int sk = 0; sk < listen_socket_count; sk++)
2284 FD_SET(listen_sockets[sk], &select_listen);
2285 if (listen_sockets[sk] > max_socket) max_socket = listen_sockets[sk];
2288 DEBUG(D_any) debug_printf("Listening...\n");
2290 /* In rare cases we may have had a SIGCHLD signal in the time between
2291 setting the handler (below) and getting back here. If so, pretend that the
2292 select() was interrupted so that we reap the child. This might still leave
2293 a small window when a SIGCHLD could get lost. However, since we use SIGCHLD
2294 only to do the reaping more quickly, it shouldn't result in anything other
2295 than a delay until something else causes a wake-up. */
2303 lcount = select(max_socket + 1, (SELECT_ARG2_TYPE *)&select_listen,
2308 select_failed = TRUE;
2312 /* Clean up any subprocesses that may have terminated. We need to do this
2313 here so that smtp_accept_max_per_host works when a connection to that host
2314 has completed, and we are about to accept a new one. When this code was
2315 later in the sequence, a new connection could be rejected, even though an
2316 old one had just finished. Preserve the errno from any select() failure for
2317 the use of the common select/accept error processing below. */
2319 select_errno = errno;
2320 handle_ending_processes();
2321 errno = select_errno;
2324 /* Create or rotate any required keys */
2328 /* Loop for all the sockets that are currently ready to go. If select
2329 actually failed, we have set the count to 1 and select_failed=TRUE, so as
2330 to use the common error code for select/accept below. */
2332 while (lcount-- > 0)
2334 int accept_socket = -1;
2338 if ( daemon_notifier_fd >= 0
2339 && FD_ISSET(daemon_notifier_fd, &select_listen))
2341 FD_CLR(daemon_notifier_fd, &select_listen);
2342 sigalrm_seen = daemon_notification();
2343 break; /* to top of daemon loop */
2345 for (int sk = 0; sk < listen_socket_count; sk++)
2346 if (FD_ISSET(listen_sockets[sk], &select_listen))
2348 len = sizeof(accepted);
2349 accept_socket = accept(listen_sockets[sk],
2350 (struct sockaddr *)&accepted, &len);
2351 FD_CLR(listen_sockets[sk], &select_listen);
2356 /* If select or accept has failed and this was not caused by an
2357 interruption, log the incident and try again. With asymmetric TCP/IP
2358 routing errors such as "No route to network" have been seen here. Also
2359 "connection reset by peer" has been seen. These cannot be classed as
2360 disastrous errors, but they could fill up a lot of log. The code in smail
2361 crashes the daemon after 10 successive failures of accept, on the grounds
2362 that some OS fail continuously. Exim originally followed suit, but this
2363 appears to have caused problems. Now it just keeps going, but instead of
2364 logging each error, it batches them up when they are continuous. */
2366 if (accept_socket < 0 && errno != EINTR)
2368 if (accept_retry_count == 0)
2370 accept_retry_errno = errno;
2371 accept_retry_select_failed = select_failed;
2375 if (errno != accept_retry_errno ||
2376 select_failed != accept_retry_select_failed ||
2377 accept_retry_count >= 50)
2379 log_write(0, LOG_MAIN | ((accept_retry_count >= 50)? LOG_PANIC : 0),
2380 "%d %s() failure%s: %s",
2382 accept_retry_select_failed? "select" : "accept",
2383 (accept_retry_count == 1)? "" : "s",
2384 strerror(accept_retry_errno));
2386 accept_retry_count = 0;
2387 accept_retry_errno = errno;
2388 accept_retry_select_failed = select_failed;
2391 accept_retry_count++;
2396 if (accept_retry_count > 0)
2398 log_write(0, LOG_MAIN, "%d %s() failure%s: %s",
2400 accept_retry_select_failed? "select" : "accept",
2401 (accept_retry_count == 1)? "" : "s",
2402 strerror(accept_retry_errno));
2404 accept_retry_count = 0;
2408 /* If select/accept succeeded, deal with the connection. */
2410 if (accept_socket >= 0)
2412 if (inetd_wait_timeout)
2413 last_connection_time = time(NULL);
2414 handle_smtp_call(listen_sockets, listen_socket_count, accept_socket,
2415 (struct sockaddr *)&accepted);
2420 /* If not listening, then just sleep for the queue interval. If we woke
2421 up early the last time for some other signal, it won't matter because
2422 the alarm signal will wake at the right time. This code originally used
2423 sleep() but it turns out that on the FreeBSD system, sleep() is not inter-
2424 rupted by signals, so it wasn't waking up for SIGALRM or SIGCHLD. Luckily
2425 select() can be used as an interruptible sleep() on all versions of Unix. */
2430 tv.tv_sec = queue_interval;
2432 select(0, NULL, NULL, NULL, &tv);
2433 handle_ending_processes();
2436 /* Re-enable the SIGCHLD handler if it has been run. It can't do it
2437 for itself, because it isn't doing the waiting itself. */
2441 sigchld_seen = FALSE;
2442 os_non_restarting_signal(SIGCHLD, main_sigchld_handler);
2445 /* Handle being woken by SIGHUP. We know at this point that the result
2446 of accept() has been dealt with, so we can re-exec exim safely, first
2447 closing the listening sockets so that they can be reused. Cancel any pending
2448 alarm in case it is just about to go off, and set SIGHUP to be ignored so
2449 that another HUP in quick succession doesn't clobber the new daemon before it
2450 gets going. All log files get closed by the close-on-exec flag; however, if
2451 the exec fails, we need to close the logs. */
2455 log_write(0, LOG_MAIN, "pid %d: SIGHUP received: re-exec daemon",
2457 close_daemon_sockets(daemon_notifier_fd,
2458 listen_sockets, listen_socket_count);
2460 signal(SIGHUP, SIG_IGN);
2461 sighup_argv[0] = exim_path;
2463 execv(CS exim_path, (char *const *)sighup_argv);
2464 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "pid %d: exec of %s failed: %s",
2465 getpid(), exim_path, strerror(errno));
2469 } /* End of main loop */
2471 /* Control never reaches here */
2476 /* End of exim_daemon.c */