1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
5 /* Copyright (c) University of Cambridge 1995 - 2018 */
6 /* See the file NOTICE for conditions of use and distribution. */
8 /* Functions concerned with running Exim as a daemon */
14 /* Structure for holding data for each SMTP connection */
16 typedef struct smtp_slot {
17 pid_t pid; /* pid of the spawned reception process */
18 uschar *host_address; /* address of the client host */
21 /* An empty slot for initializing (Standard C does not allow constructor
22 expressions in assignments except as initializers in declarations). */
24 static smtp_slot empty_smtp_slot = { .pid = 0, .host_address = NULL };
28 /*************************************************
29 * Local static variables *
30 *************************************************/
32 static SIGNAL_BOOL sigchld_seen;
33 static SIGNAL_BOOL sighup_seen;
34 static SIGNAL_BOOL sigterm_seen;
36 static int accept_retry_count = 0;
37 static int accept_retry_errno;
38 static BOOL accept_retry_select_failed;
40 static int queue_run_count = 0;
41 static pid_t *queue_pid_slots = NULL;
42 static smtp_slot *smtp_slots = NULL;
44 static BOOL write_pid = TRUE;
48 /*************************************************
50 *************************************************/
52 /* All this handler does is to set a flag and re-enable the signal.
54 Argument: the signal number
59 sighup_handler(int sig)
61 sig = sig; /* Keep picky compilers happy */
63 signal(SIGHUP, sighup_handler);
68 /*************************************************
69 * SIGCHLD handler for main daemon process *
70 *************************************************/
72 /* Don't re-enable the handler here, since we aren't doing the
73 waiting here. If the signal is re-enabled, there will just be an
74 infinite sequence of calls to this handler. The SIGCHLD signal is
75 used just as a means of waking up the daemon so that it notices
76 terminated subprocesses as soon as possible.
78 Argument: the signal number
83 main_sigchld_handler(int sig)
85 sig = sig; /* Keep picky compilers happy */
86 os_non_restarting_signal(SIGCHLD, SIG_DFL);
91 /* SIGTERM handler. Try to get the damon pif file removed
95 main_sigterm_handler(int sig)
103 /*************************************************
104 * Unexpected errors in SMTP calls *
105 *************************************************/
107 /* This function just saves a bit of repetitious coding.
110 log_msg Text of message to be logged
111 smtp_msg Text of SMTP error message
112 was_errno The failing errno
118 never_error(uschar *log_msg, uschar *smtp_msg, int was_errno)
120 uschar *emsg = was_errno <= 0
121 ? US"" : string_sprintf(": %s", strerror(was_errno));
122 log_write(0, LOG_MAIN|LOG_PANIC, "%s%s", log_msg, emsg);
123 if (smtp_out) smtp_printf("421 %s\r\n", FALSE, smtp_msg);
129 /*************************************************
130 * Handle a connected SMTP call *
131 *************************************************/
133 /* This function is called when an SMTP connection has been accepted.
134 If there are too many, give an error message and close down. Otherwise
135 spin off a sub-process to handle the call. The list of listening sockets
136 is required so that they can be closed in the sub-process. Take care not to
137 leak store in this process - reset the stacking pool at the end.
140 listen_sockets sockets which are listening for incoming calls
141 listen_socket_count count of listening sockets
142 accept_socket socket of the current accepted call
143 accepted socket information about the current call
149 handle_smtp_call(int *listen_sockets, int listen_socket_count,
150 int accept_socket, struct sockaddr *accepted)
153 union sockaddr_46 interface_sockaddr;
154 EXIM_SOCKLEN_T ifsize = sizeof(interface_sockaddr);
155 int dup_accept_socket = -1;
156 int max_for_this_host = 0;
157 int save_log_selector = *log_selector;
160 rmark reset_point = store_mark();
162 /* Make the address available in ASCII representation, and also fish out
165 sender_host_address = host_ntoa(-1, accepted, NULL, &sender_host_port);
166 DEBUG(D_any) debug_printf("Connection request from %s port %d\n",
167 sender_host_address, sender_host_port);
169 /* Set up the output stream, check the socket has duplicated, and set up the
170 input stream. These operations fail only the exceptional circumstances. Note
171 that never_error() won't use smtp_out if it is NULL. */
173 if (!(smtp_out = fdopen(accept_socket, "wb")))
175 never_error(US"daemon: fdopen() for smtp_out failed", US"", errno);
179 if ((dup_accept_socket = dup(accept_socket)) < 0)
181 never_error(US"daemon: couldn't dup socket descriptor",
182 US"Connection setup failed", errno);
186 if (!(smtp_in = fdopen(dup_accept_socket, "rb")))
188 never_error(US"daemon: fdopen() for smtp_in failed",
189 US"Connection setup failed", errno);
193 /* Get the data for the local interface address. Panic for most errors, but
194 "connection reset by peer" just means the connection went away. */
196 if (getsockname(accept_socket, (struct sockaddr *)(&interface_sockaddr),
199 log_write(0, LOG_MAIN | ((errno == ECONNRESET)? 0 : LOG_PANIC),
200 "getsockname() failed: %s", strerror(errno));
201 smtp_printf("421 Local problem: getsockname() failed; please try again later\r\n", FALSE);
205 interface_address = host_ntoa(-1, &interface_sockaddr, NULL, &interface_port);
206 DEBUG(D_interface) debug_printf("interface address=%s port=%d\n",
207 interface_address, interface_port);
209 /* Build a string identifying the remote host and, if requested, the port and
210 the local interface data. This is for logging; at the end of this function the
211 memory is reclaimed. */
213 whofrom = string_append(NULL, 3, "[", sender_host_address, "]");
215 if (LOGGING(incoming_port))
216 whofrom = string_fmt_append(whofrom, ":%d", sender_host_port);
218 if (LOGGING(incoming_interface))
219 whofrom = string_fmt_append(whofrom, " I=[%s]:%d",
220 interface_address, interface_port);
222 (void) string_from_gstring(whofrom); /* Terminate the newly-built string */
224 /* Check maximum number of connections. We do not check for reserved
225 connections or unacceptable hosts here. That is done in the subprocess because
226 it might take some time. */
228 if (smtp_accept_max > 0 && smtp_accept_count >= smtp_accept_max)
230 DEBUG(D_any) debug_printf("rejecting SMTP connection: count=%d max=%d\n",
231 smtp_accept_count, smtp_accept_max);
232 smtp_printf("421 Too many concurrent SMTP connections; "
233 "please try again later.\r\n", FALSE);
234 log_write(L_connection_reject,
235 LOG_MAIN, "Connection from %s refused: too many connections",
240 /* If a load limit above which only reserved hosts are acceptable is defined,
241 get the load average here, and if there are in fact no reserved hosts, do
242 the test right away (saves a fork). If there are hosts, do the check in the
243 subprocess because it might take time. */
245 if (smtp_load_reserve >= 0)
247 load_average = OS_GETLOADAVG();
248 if (smtp_reserve_hosts == NULL && load_average > smtp_load_reserve)
250 DEBUG(D_any) debug_printf("rejecting SMTP connection: load average = %.2f\n",
251 (double)load_average/1000.0);
252 smtp_printf("421 Too much load; please try again later.\r\n", FALSE);
253 log_write(L_connection_reject,
254 LOG_MAIN, "Connection from %s refused: load average = %.2f",
255 whofrom->s, (double)load_average/1000.0);
260 /* Check that one specific host (strictly, IP address) is not hogging
261 resources. This is done here to prevent a denial of service attack by someone
262 forcing you to fork lots of times before denying service. The value of
263 smtp_accept_max_per_host is a string which is expanded. This makes it possible
264 to provide host-specific limits according to $sender_host address, but because
265 this is in the daemon mainline, only fast expansions (such as inline address
266 checks) should be used. The documentation is full of warnings. */
268 if (smtp_accept_max_per_host != NULL)
270 uschar *expanded = expand_string(smtp_accept_max_per_host);
271 if (expanded == NULL)
273 if (!f.expand_string_forcedfail)
274 log_write(0, LOG_MAIN|LOG_PANIC, "expansion of smtp_accept_max_per_host "
275 "failed for %s: %s", whofrom->s, expand_string_message);
277 /* For speed, interpret a decimal number inline here */
280 uschar *s = expanded;
282 max_for_this_host = max_for_this_host * 10 + *s++ - '0';
284 log_write(0, LOG_MAIN|LOG_PANIC, "expansion of smtp_accept_max_per_host "
285 "for %s contains non-digit: %s", whofrom->s, expanded);
289 /* If we have fewer connections than max_for_this_host, we can skip the tedious
290 per host_address checks. Note that at this stage smtp_accept_count contains the
291 count of *other* connections, not including this one. */
293 if ((max_for_this_host > 0) &&
294 (smtp_accept_count >= max_for_this_host))
296 int host_accept_count = 0;
297 int other_host_count = 0; /* keep a count of non matches to optimise */
299 for (int i = 0; i < smtp_accept_max; ++i)
300 if (smtp_slots[i].host_address)
302 if (Ustrcmp(sender_host_address, smtp_slots[i].host_address) == 0)
307 /* Testing all these strings is expensive - see if we can drop out
308 early, either by hitting the target, or finding there are not enough
309 connections left to make the target. */
311 if ((host_accept_count >= max_for_this_host) ||
312 ((smtp_accept_count - other_host_count) < max_for_this_host))
316 if (host_accept_count >= max_for_this_host)
318 DEBUG(D_any) debug_printf("rejecting SMTP connection: too many from this "
319 "IP address: count=%d max=%d\n",
320 host_accept_count, max_for_this_host);
321 smtp_printf("421 Too many concurrent SMTP connections "
322 "from this IP address; please try again later.\r\n", FALSE);
323 log_write(L_connection_reject,
324 LOG_MAIN, "Connection from %s refused: too many connections "
325 "from that IP address", whofrom->s);
330 /* OK, the connection count checks have been passed. Before we can fork the
331 accepting process, we must first log the connection if requested. This logging
332 used to happen in the subprocess, but doing that means that the value of
333 smtp_accept_count can be out of step by the time it is logged. So we have to do
334 the logging here and accept the performance cost. Note that smtp_accept_count
335 hasn't yet been incremented to take account of this connection.
337 In order to minimize the cost (because this is going to happen for every
338 connection), do a preliminary selector test here. This saves ploughing through
339 the generalized logging code each time when the selector is false. If the
340 selector is set, check whether the host is on the list for logging. If not,
341 arrange to unset the selector in the subprocess. */
343 if (LOGGING(smtp_connection))
345 uschar *list = hosts_connection_nolog;
346 memset(sender_host_cache, 0, sizeof(sender_host_cache));
347 if (list != NULL && verify_check_host(&list) == OK)
348 save_log_selector &= ~L_smtp_connection;
350 log_write(L_smtp_connection, LOG_MAIN, "SMTP connection from %s "
351 "(TCP/IP connection count = %d)", whofrom->s, smtp_accept_count + 1);
354 /* Now we can fork the accepting process; do a lookup tidy, just in case any
355 expansion above did a lookup. */
360 /* Handle the child process */
365 int queue_only_reason = 0;
366 int old_pool = store_pool;
367 int save_debug_selector = debug_selector;
368 BOOL local_queue_only;
369 BOOL session_local_queue_only;
371 struct sigaction act;
374 smtp_accept_count++; /* So that it includes this process */
376 /* May have been modified for the subprocess */
378 *log_selector = save_log_selector;
380 /* Get the local interface address into permanent store */
382 store_pool = POOL_PERM;
383 interface_address = string_copy(interface_address);
384 store_pool = old_pool;
386 /* Check for a tls-on-connect port */
388 if (host_is_tls_on_connect_port(interface_port)) tls_in.on_connect = TRUE;
390 /* Expand smtp_active_hostname if required. We do not do this any earlier,
391 because it may depend on the local interface address (indeed, that is most
392 likely what it depends on.) */
394 smtp_active_hostname = primary_hostname;
395 if (raw_active_hostname)
397 uschar * nah = expand_string(raw_active_hostname);
400 if (!f.expand_string_forcedfail)
402 log_write(0, LOG_MAIN|LOG_PANIC, "failed to expand \"%s\" "
403 "(smtp_active_hostname): %s", raw_active_hostname,
404 expand_string_message);
405 smtp_printf("421 Local configuration error; "
406 "please try again later.\r\n", FALSE);
409 exim_underbar_exit(EXIT_FAILURE);
412 else if (*nah) smtp_active_hostname = nah;
415 /* Initialize the queueing flags */
418 session_local_queue_only = queue_only;
420 /* Close the listening sockets, and set the SIGCHLD handler to SIG_IGN.
421 We also attempt to set things up so that children are automatically reaped,
422 but just in case this isn't available, there's a paranoid waitpid() in the
423 loop too (except for systems where we are sure it isn't needed). See the more
424 extensive comment before the reception loop in exim.c for a fuller
425 explanation of this logic. */
427 for (i = 0; i < listen_socket_count; i++) (void)close(listen_sockets[i]);
429 /* Set FD_CLOEXEC on the SMTP socket. We don't want any rogue child processes
430 to be able to communicate with them, under any circumstances. */
431 (void)fcntl(accept_socket, F_SETFD,
432 fcntl(accept_socket, F_GETFD) | FD_CLOEXEC);
433 (void)fcntl(dup_accept_socket, F_SETFD,
434 fcntl(dup_accept_socket, F_GETFD) | FD_CLOEXEC);
437 act.sa_handler = SIG_IGN;
438 sigemptyset(&(act.sa_mask));
439 act.sa_flags = SA_NOCLDWAIT;
440 sigaction(SIGCHLD, &act, NULL);
442 signal(SIGCHLD, SIG_IGN);
444 signal(SIGTERM, SIG_DFL);
446 /* Attempt to get an id from the sending machine via the RFC 1413
447 protocol. We do this in the sub-process in order not to hold up the
448 main process if there is any delay. Then set up the fullhost information
449 in case there is no HELO/EHLO.
451 If debugging is enabled only for the daemon, we must turn if off while
452 finding the id, but turn it on again afterwards so that information about the
453 incoming connection is output. */
455 if (f.debug_daemon) debug_selector = 0;
456 verify_get_ident(IDENT_PORT);
457 host_build_sender_fullhost();
458 debug_selector = save_debug_selector;
461 debug_printf("Process %d is handling incoming connection from %s\n",
462 (int)getpid(), sender_fullhost);
464 /* Now disable debugging permanently if it's required only for the daemon
467 if (f.debug_daemon) debug_selector = 0;
469 /* If there are too many child processes for immediate delivery,
470 set the session_local_queue_only flag, which is initialized from the
471 configured value and may therefore already be TRUE. Leave logging
472 till later so it will have a message id attached. Note that there is no
473 possibility of re-calculating this per-message, because the value of
474 smtp_accept_count does not change in this subprocess. */
476 if (smtp_accept_queue > 0 && smtp_accept_count > smtp_accept_queue)
478 session_local_queue_only = TRUE;
479 queue_only_reason = 1;
482 /* Handle the start of the SMTP session, then loop, accepting incoming
483 messages from the SMTP connection. The end will come at the QUIT command,
484 when smtp_setup_msg() returns 0. A break in the connection causes the
485 process to die (see accept.c).
487 NOTE: We do *not* call smtp_log_no_mail() if smtp_start_session() fails,
488 because a log line has already been written for all its failure exists
489 (usually "connection refused: <reason>") and writing another one is
490 unnecessary clutter. */
492 if (!smtp_start_session())
496 exim_underbar_exit(EXIT_SUCCESS);
502 message_id[0] = 0; /* Clear out any previous message_id */
503 reset_point = store_mark(); /* Save current store high water point */
506 debug_printf("Process %d is ready for new message\n", (int)getpid());
508 /* Smtp_setup_msg() returns 0 on QUIT or if the call is from an
509 unacceptable host or if an ACL "drop" command was triggered, -1 on
510 connection lost, and +1 on validly reaching DATA. Receive_msg() almost
511 always returns TRUE when smtp_input is true; just retry if no message was
512 accepted (can happen for invalid message parameters). However, it can yield
513 FALSE if the connection was forcibly dropped by the DATA ACL. */
515 if ((rc = smtp_setup_msg()) > 0)
517 BOOL ok = receive_msg(FALSE);
518 search_tidyup(); /* Close cached databases */
519 if (!ok) /* Connection was dropped */
521 cancel_cutthrough_connection(TRUE, US"receive dropped");
523 smtp_log_no_mail(); /* Log no mail if configured */
524 exim_underbar_exit(EXIT_SUCCESS);
526 if (message_id[0] == 0) continue; /* No message was accepted */
532 int fd = fileno(smtp_in);
536 /* drain socket, for clean TCP FINs */
537 if (fcntl(fd, F_SETFL, O_NONBLOCK) == 0)
538 for(int i = 16; read(fd, buf, sizeof(buf)) > 0 && i > 0; ) i--;
540 cancel_cutthrough_connection(TRUE, US"message setup dropped");
542 smtp_log_no_mail(); /* Log no mail if configured */
544 /*XXX should we pause briefly, hoping that the client will be the
545 active TCP closer hence get the TCP_WAIT endpoint? */
546 DEBUG(D_receive) debug_printf("SMTP>>(close on process exit)\n");
547 exim_underbar_exit(rc ? EXIT_FAILURE : EXIT_SUCCESS);
550 /* Show the recipients when debugging */
555 debug_printf("Sender: %s\n", sender_address);
558 debug_printf("Recipients:\n");
559 for (int i = 0; i < recipients_count; i++)
560 debug_printf(" %s\n", recipients_list[i].address);
564 /* A message has been accepted. Clean up any previous delivery processes
565 that have completed and are defunct, on systems where they don't go away
566 by themselves (see comments when setting SIG_IGN above). On such systems
567 (if any) these delivery processes hang around after termination until
568 the next message is received. */
570 #ifndef SIG_IGN_WORKS
571 while (waitpid(-1, NULL, WNOHANG) > 0);
574 /* Reclaim up the store used in accepting this message */
577 int r = receive_messagecount;
578 BOOL q = f.queue_only_policy;
579 smtp_reset(reset_point);
581 f.queue_only_policy = q;
582 receive_messagecount = r;
585 /* If queue_only is set or if there are too many incoming connections in
586 existence, session_local_queue_only will be TRUE. If it is not, check
587 whether we have received too many messages in this session for immediate
590 if (!session_local_queue_only &&
591 smtp_accept_queue_per_connection > 0 &&
592 receive_messagecount > smtp_accept_queue_per_connection)
594 session_local_queue_only = TRUE;
595 queue_only_reason = 2;
598 /* Initialize local_queue_only from session_local_queue_only. If it is not
599 true, and queue_only_load is set, check that the load average is below it.
600 If local_queue_only is set by this means, we also set if for the session if
601 queue_only_load_latch is true (the default). This means that, once set,
602 local_queue_only remains set for any subsequent messages on the same SMTP
603 connection. This is a deliberate choice; even though the load average may
604 fall, it doesn't seem right to deliver later messages on the same call when
605 not delivering earlier ones. However, the are special circumstances such as
606 very long-lived connections from scanning appliances where this is not the
607 best strategy. In such cases, queue_only_load_latch should be set false. */
609 if ( !(local_queue_only = session_local_queue_only)
610 && queue_only_load >= 0
611 && (local_queue_only = (load_average = OS_GETLOADAVG()) > queue_only_load)
614 queue_only_reason = 3;
615 if (queue_only_load_latch) session_local_queue_only = TRUE;
618 /* Log the queueing here, when it will get a message id attached, but
619 not if queue_only is set (case 0). */
621 if (local_queue_only) switch(queue_only_reason)
623 case 1: log_write(L_delay_delivery,
624 LOG_MAIN, "no immediate delivery: too many connections "
625 "(%d, max %d)", smtp_accept_count, smtp_accept_queue);
628 case 2: log_write(L_delay_delivery,
629 LOG_MAIN, "no immediate delivery: more than %d messages "
630 "received in one connection", smtp_accept_queue_per_connection);
633 case 3: log_write(L_delay_delivery,
634 LOG_MAIN, "no immediate delivery: load average %.2f",
635 (double)load_average/1000.0);
639 /* If a delivery attempt is required, spin off a new process to handle it.
640 If we are not root, we have to re-exec exim unless deliveries are being
641 done unprivileged. */
643 else if ( (!f.queue_only_policy || f.queue_smtp)
644 && !f.deliver_freeze)
648 /* Before forking, ensure that the C output buffer is flushed. Otherwise
649 anything that it in it will get duplicated, leading to duplicate copies
650 of the pending output. */
654 if ((dpid = fork()) == 0)
656 (void)fclose(smtp_in);
657 (void)fclose(smtp_out);
659 /* Don't ever molest the parent's SSL connection, but do clean up
660 the data structures if necessary. */
663 tls_close(NULL, TLS_NO_SHUTDOWN);
666 /* Reset SIGHUP and SIGCHLD in the child in both cases. */
668 signal(SIGHUP, SIG_DFL);
669 signal(SIGCHLD, SIG_DFL);
670 signal(SIGTERM, SIG_DFL);
672 if (geteuid() != root_uid && !deliver_drop_privilege)
674 signal(SIGALRM, SIG_DFL);
675 delivery_re_exec(CEE_EXEC_PANIC);
676 /* Control does not return here. */
679 /* No need to re-exec; SIGALRM remains set to the default handler */
681 (void) deliver_message(message_id, FALSE, FALSE);
683 exim_underbar_exit(EXIT_SUCCESS);
688 release_cutthrough_connection(US"passed for delivery");
689 DEBUG(D_any) debug_printf("forked delivery process %d\n", (int)dpid);
693 cancel_cutthrough_connection(TRUE, US"delivery fork failed");
694 log_write(0, LOG_MAIN|LOG_PANIC, "daemon: delivery process fork "
695 "failed: %s", strerror(errno));
702 /* Carrying on in the parent daemon process... Can't do much if the fork
703 failed. Otherwise, keep count of the number of accepting processes and
704 remember the pid for ticking off when the child completes. */
707 never_error(US"daemon: accept process fork failed", US"Fork failed", errno);
710 for (int i = 0; i < smtp_accept_max; ++i)
711 if (smtp_slots[i].pid <= 0)
713 smtp_slots[i].pid = pid;
714 /* Connection closes come asyncronously, so we cannot stack this store */
715 if (smtp_accept_max_per_host)
716 smtp_slots[i].host_address = string_copy_malloc(sender_host_address);
720 DEBUG(D_any) debug_printf("%d SMTP accept process%s running\n",
721 smtp_accept_count, smtp_accept_count == 1 ? "" : "es");
724 /* Get here via goto in error cases */
728 /* Close the streams associated with the socket which will also close the
729 socket fds in this process. We can't do anything if fclose() fails, but
730 logging brings it to someone's attention. However, "connection reset by peer"
731 isn't really a problem, so skip that one. On Solaris, a dropped connection can
732 manifest itself as a broken pipe, so drop that one too. If the streams don't
733 exist, something went wrong while setting things up. Make sure the socket
734 descriptors are closed, in order to drop the connection. */
738 if (fclose(smtp_out) != 0 && errno != ECONNRESET && errno != EPIPE)
739 log_write(0, LOG_MAIN|LOG_PANIC, "daemon: fclose(smtp_out) failed: %s",
743 else (void)close(accept_socket);
747 if (fclose(smtp_in) != 0 && errno != ECONNRESET && errno != EPIPE)
748 log_write(0, LOG_MAIN|LOG_PANIC, "daemon: fclose(smtp_in) failed: %s",
752 else (void)close(dup_accept_socket);
754 /* Release any store used in this process, including the store used for holding
755 the incoming host address and an expanded active_hostname. */
759 sender_host_address = NULL;
760 store_reset(reset_point);
761 sender_host_address = NULL;
767 /*************************************************
768 * Check wildcard listen special cases *
769 *************************************************/
771 /* This function is used when binding and listening on lists of addresses and
772 ports. It tests for special cases of wildcard listening, when IPv4 and IPv6
773 sockets may interact in different ways in different operating systems. It is
774 passed an error number, the list of listening addresses, and the current
775 address. Two checks are available: for a previous wildcard IPv6 address, or for
776 a following wildcard IPv4 address, in both cases on the same port.
778 In practice, pairs of wildcard addresses should be adjacent in the address list
779 because they are sorted that way below.
783 addresses the list of addresses
784 ipa the current IP address
785 back if TRUE, check for previous wildcard IPv6 address
786 if FALSE, check for a following wildcard IPv4 address
788 Returns: TRUE or FALSE
792 check_special_case(int eno, ip_address_item *addresses, ip_address_item *ipa,
795 ip_address_item *ipa2;
797 /* For the "back" case, if the failure was "address in use" for a wildcard IPv4
798 address, seek a previous IPv6 wildcard address on the same port. As it is
799 previous, it must have been successfully bound and be listening. Flag it as a
800 "6 including 4" listener. */
804 if (eno != EADDRINUSE || ipa->address[0] != 0) return FALSE;
805 for (ipa2 = addresses; ipa2 != ipa; ipa2 = ipa2->next)
807 if (ipa2->address[1] == 0 && ipa2->port == ipa->port)
809 ipa2->v6_include_v4 = TRUE;
815 /* For the "forward" case, if the current address is a wildcard IPv6 address,
816 we seek a following wildcard IPv4 address on the same port. */
820 if (ipa->address[0] != ':' || ipa->address[1] != 0) return FALSE;
821 for (ipa2 = ipa->next; ipa2 != NULL; ipa2 = ipa2->next)
822 if (ipa2->address[0] == 0 && ipa->port == ipa2->port) return TRUE;
831 /*************************************************
832 * Handle terminating subprocesses *
833 *************************************************/
835 /* Handle the termination of child processes. Theoretically, this need be done
836 only when sigchld_seen is TRUE, but rumour has it that some systems lose
837 SIGCHLD signals at busy times, so to be on the safe side, this function is
838 called each time round. It shouldn't be too expensive.
845 handle_ending_processes(void)
850 while ((pid = waitpid(-1, &status, WNOHANG)) > 0)
854 debug_printf("child %d ended: status=0x%x\n", (int)pid, status);
856 if (WIFEXITED(status))
857 debug_printf(" normal exit, %d\n", WEXITSTATUS(status));
858 else if (WIFSIGNALED(status))
859 debug_printf(" signal exit, signal %d%s\n", WTERMSIG(status),
860 WCOREDUMP(status) ? " (core dumped)" : "");
864 /* If it's a listening daemon for which we are keeping track of individual
865 subprocesses, deal with an accepting process that has terminated. */
870 for (i = 0; i < smtp_accept_max; i++)
871 if (smtp_slots[i].pid == pid)
873 if (smtp_slots[i].host_address)
874 store_free(smtp_slots[i].host_address);
875 smtp_slots[i] = empty_smtp_slot;
876 if (--smtp_accept_count < 0) smtp_accept_count = 0;
877 DEBUG(D_any) debug_printf("%d SMTP accept process%s now running\n",
878 smtp_accept_count, (smtp_accept_count == 1)? "" : "es");
881 if (i < smtp_accept_max) continue; /* Found an accepting process */
884 /* If it wasn't an accepting process, see if it was a queue-runner
885 process that we are tracking. */
889 int max = atoi(CS expand_string(queue_run_max));
890 for (int i = 0; i < max; i++)
891 if (queue_pid_slots[i] == pid)
893 queue_pid_slots[i] = 0;
894 if (--queue_run_count < 0) queue_run_count = 0;
895 DEBUG(D_any) debug_printf("%d queue-runner process%s now running\n",
896 queue_run_count, (queue_run_count == 1)? "" : "es");
906 set_pid_file_path(void)
908 if (override_pid_file_path)
909 pid_file_path = override_pid_file_path;
912 pid_file_path = string_sprintf("%s/exim-daemon.pid", spool_directory);
916 /* Remove the daemon's pidfile. Note: runs with root privilege,
917 as a direct child of the daemon. Does not return. */
920 delete_pid_file(void)
922 uschar * daemon_pid = string_sprintf("%d\n", (int)getppid());
926 if ((f = Ufopen(pid_file_path, "rb")))
928 if ( fgets(CS big_buffer, big_buffer_size, f)
929 && Ustrcmp(daemon_pid, big_buffer) == 0
931 if (Uunlink(pid_file_path) == 0)
934 debug_printf("%s unlink: %s\n", pid_file_path, strerror(errno));
938 debug_printf("unlinked %s\n", pid_file_path);
943 debug_printf("%s\n", string_open_failed(errno, "pid file %s",
945 exim_exit(EXIT_SUCCESS, US"pid file remover");
949 /* Called by the daemon; exec a child to get the pid file deleted
950 since we may require privs for the containing directory */
957 if (daemon_notifier_fd >= 0)
959 close(daemon_notifier_fd);
960 daemon_notifier_fd = -1;
961 #ifndef EXIM_HAVE_ABSTRACT_UNIX_SOCKETS
963 uschar * s = string_sprintf("%s/%s", spool_directory, NOTIFIER_SOCKET_NAME);
964 DEBUG(D_any) debug_printf("unlinking notifier socket %s\n", s);
970 if (f.running_in_test_harness || write_pid)
972 if ((pid = fork()) == 0)
974 if (override_pid_file_path)
975 (void)child_exec_exim(CEE_EXEC_PANIC, FALSE, NULL, FALSE, 3,
976 "-oP", override_pid_file_path, "-oPX");
978 (void)child_exec_exim(CEE_EXEC_PANIC, FALSE, NULL, FALSE, 1, "-oPX");
980 /* Control never returns here. */
985 exim_exit(EXIT_SUCCESS, US"daemon");
989 /*************************************************
990 * Listener socket for local work prompts *
991 *************************************************/
994 daemon_notifier_socket(void)
997 const uschar * where;
998 struct sockaddr_un sun = {.sun_family = AF_UNIX};
1001 DEBUG(D_any) debug_printf("creating notifier socket ");
1005 if ((fd = socket(PF_UNIX, SOCK_DGRAM|SOCK_CLOEXEC, 0)) < 0)
1008 if ((fd = socket(AF_UNIX, SOCK_DGRAM, 0)) < 0)
1010 (void)fcntl(fd, F_SETFD, fcntl(fd, F_GETFD) | FD_CLOEXEC);
1013 #ifdef EXIM_HAVE_ABSTRACT_UNIX_SOCKETS
1014 sun.sun_path[0] = 0; /* Abstract local socket addr - Linux-specific? */
1015 len = offsetof(struct sockaddr_un, sun_path) + 1
1016 + snprintf(sun.sun_path+1, sizeof(sun.sun_path)-1, "%s", NOTIFIER_SOCKET_NAME);
1017 DEBUG(D_any) debug_printf("@%s\n", sun.sun_path+1);
1018 #else /* filesystem-visible and persistent; will neeed removal */
1019 len = offsetof(struct sockaddr_un, sun_path)
1020 + snprintf(sun.sun_path, sizeof(sun.sun_path), "%s/%s",
1021 spool_directory, NOTIFIER_SOCKET_NAME);
1022 DEBUG(D_any) debug_printf("%s\n", sun.sun_path);
1026 if (bind(fd, (const struct sockaddr *)&sun, len) < 0)
1029 #ifdef SO_PASSCRED /* Linux */
1030 where = US"SO_PASSCRED";
1031 if (setsockopt(fd, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on)) < 0)
1033 #elif defined(LOCAL_CREDS) /* FreeBSD-ish */
1034 where = US"LOCAL_CREDS";
1035 if (setsockopt(fd, SOL_SOCKET, LOCAL_CREDS, &on, sizeof(on)) < 0)
1039 /* debug_printf("%s: fd %d\n", __FUNCTION__, fd); */
1040 daemon_notifier_fd = fd;
1044 log_write(0, LOG_MAIN|LOG_PANIC, "%s: %s: %s",
1045 __FUNCTION__, where, strerror(errno));
1049 static uschar queuerun_msgid[MESSAGE_ID_LENGTH+1];
1051 /* Return TRUE if a sigalrm should be emulated */
1053 daemon_notification(void)
1055 uschar buf[256], cbuf[256];
1056 struct sockaddr_un sun;
1057 struct iovec iov = {.iov_base = buf, .iov_len = sizeof(buf)-1};
1058 struct msghdr msg = { .msg_name = &sun,
1059 .msg_namelen = sizeof(sun),
1062 .msg_control = cbuf,
1063 .msg_controllen = sizeof(cbuf)
1066 struct cmsghdr * cp;
1068 buf[sizeof(buf)-1] = 0;
1069 if ((sz = recvmsg(daemon_notifier_fd, &msg, 0)) <= 0) return FALSE;
1070 if (sz >= sizeof(buf)) return FALSE;
1073 debug_printf("addrlen %d\n", msg.msg_namelen);
1075 DEBUG(D_queue_run) debug_printf("%s from addr '%s%.*s'\n", __FUNCTION__,
1076 *sun.sun_path ? "" : "@",
1077 (int)msg.msg_namelen - (*sun.sun_path ? 0 : 1),
1078 sun.sun_path + (*sun.sun_path ? 0 : 1));
1080 /* Refuse to handle the item unless the peer has good credentials */
1081 #ifdef SCM_CREDENTIALS
1082 # define EXIM_SCM_CR_TYPE SCM_CREDENTIALS
1083 #elif defined(LOCAL_CREDS) && defined(SCM_CREDS)
1084 # define EXIM_SCM_CR_TYPE SCM_CREDS
1086 /* The OS has no way to get the creds of the caller (for a unix/datagram socket.
1087 Punt; don't try to check. */
1090 #ifdef EXIM_SCM_CR_TYPE
1091 for (struct cmsghdr * cp = CMSG_FIRSTHDR(&msg);
1093 cp = CMSG_NXTHDR(&msg, cp))
1094 if (cp->cmsg_level == SOL_SOCKET && cp->cmsg_type == EXIM_SCM_CR_TYPE)
1096 # ifdef SCM_CREDENTIALS /* Linux */
1097 struct ucred * cr = (struct ucred *) CMSG_DATA(cp);
1098 if (cr->uid && cr->uid != exim_uid)
1100 DEBUG(D_queue_run) debug_printf("%s: sender creds pid %d uid %d gid %d\n",
1101 __FUNCTION__, (int)cr->pid, (int)cr->uid, (int)cr->gid);
1104 # elif defined(LOCAL_CREDS) /* BSD-ish */
1105 struct sockcred * cr = (struct sockcred *) CMSG_DATA(cp);
1106 if (cr->sc_uid && cr->sc_uid != exim_uid)
1108 DEBUG(D_queue_run) debug_printf("%s: sender creds pid ??? uid %d gid %d\n",
1109 __FUNCTION__, (int)cr->sc_uid, (int)cr->sc_gid);
1120 #ifdef EXPERIMENTAL_QUEUE_RAMP
1121 case NOTIFY_MSG_QRUN:
1122 /* this should be a message_id */
1124 debug_printf("%s: qrunner trigger: %s\n", __FUNCTION__, buf+1);
1125 memcpy(queuerun_msgid, buf+1, MESSAGE_ID_LENGTH+1);
1127 #endif /*EXPERIMENTAL_QUEUE_RAMP*/
1129 case NOTIFY_QUEUE_SIZE_REQ:
1132 int len = snprintf(CS buf, sizeof(buf), "%u", queue_count_cached());
1135 debug_printf("%s: queue size request: %s\n", __FUNCTION__, buf);
1137 if (sendto(daemon_notifier_fd, buf, len, 0,
1138 (const struct sockaddr *)&sun, msg.msg_namelen) < 0)
1139 log_write(0, LOG_MAIN|LOG_PANIC,
1140 "%s: sendto: %s\n", __FUNCTION__, strerror(errno));
1148 /*************************************************
1149 * Exim Daemon Mainline *
1150 *************************************************/
1152 /* The daemon can do two jobs, either of which is optional:
1154 (1) Listens for incoming SMTP calls and spawns off a sub-process to handle
1155 each one. This is requested by the -bd option, with -oX specifying the SMTP
1156 port on which to listen (for testing).
1158 (2) Spawns a queue-running process every so often. This is controlled by the
1159 -q option with a an interval time. (If no time is given, a single queue run
1160 is done from the main function, and control doesn't get here.)
1162 Root privilege is required in order to attach to port 25. Some systems require
1163 it when calling socket() rather than bind(). To cope with all cases, we run as
1164 root for both socket() and bind(). Some systems also require root in order to
1165 write to the pid file directory. This function must therefore be called as root
1166 if it is to work properly in all circumstances. Once the socket is bound and
1167 the pid file written, root privilege is given up if there is an exim uid.
1169 There are no arguments to this function, and it never returns. */
1175 int *listen_sockets = NULL;
1176 int listen_socket_count = 0;
1177 ip_address_item *addresses = NULL;
1178 time_t last_connection_time = (time_t)0;
1179 int local_queue_run_max = atoi(CS expand_string(queue_run_max));
1181 /* If any debugging options are set, turn on the D_pid bit so that all
1182 debugging lines get the pid added. */
1184 DEBUG(D_any|D_v) debug_selector |= D_pid;
1186 if (f.inetd_wait_mode)
1188 listen_socket_count = 1;
1189 listen_sockets = store_get(sizeof(int), FALSE);
1191 if (dup2(0, 3) == -1)
1192 log_write(0, LOG_MAIN|LOG_PANIC_DIE,
1193 "failed to dup inetd socket safely away: %s", strerror(errno));
1195 listen_sockets[0] = 3;
1201 if (debug_file == stderr)
1203 /* need a call to log_write before call to open debug_file, so that
1204 log.c:file_path has been initialised. This is unfortunate. */
1205 log_write(0, LOG_MAIN, "debugging Exim in inetd wait mode starting");
1209 exim_nullstd(); /* re-open fd2 after we just closed it again */
1210 debug_logging_activate(US"-wait", NULL);
1213 DEBUG(D_any) debug_printf("running in inetd wait mode\n");
1215 /* As per below, when creating sockets ourselves, we handle tcp_nodelay for
1216 our own buffering; we assume though that inetd set the socket REUSEADDR. */
1219 if (setsockopt(3, IPPROTO_TCP, TCP_NODELAY, US &on, sizeof(on)))
1220 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "failed to set socket NODELAY: %s",
1225 if (f.inetd_wait_mode || f.daemon_listen)
1227 /* If any option requiring a load average to be available during the
1228 reception of a message is set, call os_getloadavg() while we are root
1229 for those OS for which this is necessary the first time it is called (in
1230 order to perform an "open" on the kernel memory file). */
1232 #ifdef LOAD_AVG_NEEDS_ROOT
1233 if (queue_only_load >= 0 || smtp_load_reserve >= 0 ||
1234 (deliver_queue_load_max >= 0 && deliver_drop_privilege))
1235 (void)os_getloadavg();
1240 /* Do the preparation for setting up a listener on one or more interfaces, and
1241 possible on various ports. This is controlled by the combination of
1242 local_interfaces (which can set IP addresses and ports) and daemon_smtp_port
1243 (which is a list of default ports to use for those items in local_interfaces
1244 that do not specify a port). The -oX command line option can be used to
1245 override one or both of these options.
1247 If local_interfaces is not set, the default is to listen on all interfaces.
1248 When it is set, it can include "all IPvx interfaces" as an item. This is useful
1249 when different ports are in use.
1251 It turns out that listening on all interfaces is messy in an IPv6 world,
1252 because several different implementation approaches have been taken. This code
1253 is now supposed to work with all of them. The point of difference is whether an
1254 IPv6 socket that is listening on all interfaces will receive incoming IPv4
1255 calls or not. We also have to cope with the case when IPv6 libraries exist, but
1256 there is no IPv6 support in the kernel.
1258 . On Solaris, an IPv6 socket will accept IPv4 calls, and give them as mapped
1259 addresses. However, if an IPv4 socket is also listening on all interfaces,
1260 calls are directed to the appropriate socket.
1262 . On (some versions of) Linux, an IPv6 socket will accept IPv4 calls, and
1263 give them as mapped addresses, but an attempt also to listen on an IPv4
1264 socket on all interfaces causes an error.
1266 . On OpenBSD, an IPv6 socket will not accept IPv4 calls. You have to set up
1267 two sockets if you want to accept both kinds of call.
1269 . FreeBSD is like OpenBSD, but it has the IPV6_V6ONLY socket option, which
1270 can be turned off, to make it behave like the versions of Linux described
1273 . I heard a report that the USAGI IPv6 stack for Linux has implemented
1276 So, what we do when IPv6 is supported is as follows:
1278 (1) After it is set up, the list of interfaces is scanned for wildcard
1279 addresses. If an IPv6 and an IPv4 wildcard are both found for the same
1280 port, the list is re-arranged so that they are together, with the IPv6
1283 (2) If the creation of a wildcard IPv6 socket fails, we just log the error and
1284 carry on if an IPv4 wildcard socket for the same port follows later in the
1285 list. This allows Exim to carry on in the case when the kernel has no IPv6
1288 (3) Having created an IPv6 wildcard socket, we try to set IPV6_V6ONLY if that
1289 option is defined. However, if setting fails, carry on regardless (but log
1292 (4) If binding or listening on an IPv6 wildcard socket fails, it is a serious
1295 (5) If binding or listening on an IPv4 wildcard socket fails with the error
1296 EADDRINUSE, and a previous interface was an IPv6 wildcard for the same
1297 port (which must have succeeded or we wouldn't have got this far), we
1298 assume we are in the situation where just a single socket is permitted,
1299 and ignore the error.
1303 The preparation code decodes options and sets up the relevant data. We do this
1304 first, so that we can return non-zero if there are any syntax errors, and also
1307 if (f.daemon_listen && !f.inetd_wait_mode)
1309 int *default_smtp_port;
1313 const uschar * list;
1314 uschar *local_iface_source = US"local_interfaces";
1315 ip_address_item *ipa;
1316 ip_address_item **pipa;
1318 /* If -oX was used, disable the writing of a pid file unless -oP was
1319 explicitly used to force it. Then scan the string given to -oX. Any items
1320 that contain neither a dot nor a colon are used to override daemon_smtp_port.
1321 Any other items are used to override local_interfaces. */
1323 if (override_local_interfaces)
1325 gstring * new_smtp_port = NULL;
1326 gstring * new_local_interfaces = NULL;
1328 if (!override_pid_file_path) write_pid = FALSE;
1330 list = override_local_interfaces;
1332 while ((s = string_nextinlist(&list, &sep, big_buffer, big_buffer_size)))
1335 gstring ** gp = Ustrpbrk(s, ".:") ? &new_local_interfaces : &new_smtp_port;
1341 *gp = string_catn(*gp, US"<", 1);
1344 *gp = string_catn(*gp, joinstr, 2);
1345 *gp = string_cat (*gp, s);
1350 daemon_smtp_port = string_from_gstring(new_smtp_port);
1351 DEBUG(D_any) debug_printf("daemon_smtp_port overridden by -oX:\n %s\n",
1355 if (new_local_interfaces)
1357 local_interfaces = string_from_gstring(new_local_interfaces);
1358 local_iface_source = US"-oX data";
1359 DEBUG(D_any) debug_printf("local_interfaces overridden by -oX:\n %s\n",
1364 /* Create a list of default SMTP ports, to be used if local_interfaces
1365 contains entries without explicit ports. First count the number of ports, then
1366 build a translated list in a vector. */
1368 list = daemon_smtp_port;
1370 while ((s = string_nextinlist(&list, &sep, big_buffer, big_buffer_size)))
1372 default_smtp_port = store_get((pct+1) * sizeof(int), FALSE);
1373 list = daemon_smtp_port;
1376 (s = string_nextinlist(&list, &sep, big_buffer, big_buffer_size));
1382 default_smtp_port[pct] = Ustrtol(s, &end, 0);
1383 if (end != s + Ustrlen(s))
1384 log_write(0, LOG_PANIC_DIE|LOG_CONFIG, "invalid SMTP port: %s", s);
1388 struct servent *smtp_service = getservbyname(CS s, "tcp");
1390 log_write(0, LOG_PANIC_DIE|LOG_CONFIG, "TCP port \"%s\" not found", s);
1391 default_smtp_port[pct] = ntohs(smtp_service->s_port);
1394 default_smtp_port[pct] = 0;
1396 /* Check the list of TLS-on-connect ports and do name lookups if needed */
1398 list = tls_in.on_connect_ports;
1400 while ((s = string_nextinlist(&list, &sep, big_buffer, big_buffer_size)))
1405 list = tls_in.on_connect_ports;
1406 tls_in.on_connect_ports = NULL;
1408 while ((s = string_nextinlist(&list, &sep, big_buffer, big_buffer_size)))
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 s = string_sprintf("%d", (int)ntohs(smtp_service->s_port));
1417 g = string_append_listele(g, ':', s);
1420 tls_in.on_connect_ports = g->s;
1424 /* Create the list of local interfaces, possibly with ports included. This
1425 list may contain references to 0.0.0.0 and ::0 as wildcards. These special
1426 values are converted below. */
1428 addresses = host_build_ifacelist(local_interfaces, local_iface_source);
1430 /* In the list of IP addresses, convert 0.0.0.0 into an empty string, and ::0
1431 into the string ":". We use these to recognize wildcards in IPv4 and IPv6. In
1432 fact, many IP stacks recognize 0.0.0.0 and ::0 and handle them as wildcards
1433 anyway, but we need to know which are the wildcard addresses, and the shorter
1436 In the same scan, fill in missing port numbers from the default list. When
1437 there is more than one item in the list, extra items are created. */
1439 for (ipa = addresses; ipa; ipa = ipa->next)
1441 if (Ustrcmp(ipa->address, "0.0.0.0") == 0)
1442 ipa->address[0] = 0;
1443 else if (Ustrcmp(ipa->address, "::0") == 0)
1445 ipa->address[0] = ':';
1446 ipa->address[1] = 0;
1449 if (ipa->port > 0) continue;
1451 if (daemon_smtp_port[0] <= 0)
1452 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "no port specified for interface "
1453 "%s and daemon_smtp_port is unset; cannot start daemon",
1454 ipa->address[0] == 0 ? US"\"all IPv4\"" :
1455 ipa->address[1] == 0 ? US"\"all IPv6\"" : ipa->address);
1457 ipa->port = default_smtp_port[0];
1458 for (int i = 1; default_smtp_port[i] > 0; i++)
1460 ip_address_item *new = store_get(sizeof(ip_address_item), FALSE);
1462 memcpy(new->address, ipa->address, Ustrlen(ipa->address) + 1);
1463 new->port = default_smtp_port[i];
1464 new->next = ipa->next;
1470 /* Scan the list of addresses for wildcards. If we find an IPv4 and an IPv6
1471 wildcard for the same port, ensure that (a) they are together and (b) the
1472 IPv6 address comes first. This makes handling the messy features easier, and
1473 also simplifies the construction of the "daemon started" log line. */
1476 for (ipa = addresses; ipa; pipa = &ipa->next, ipa = ipa->next)
1478 ip_address_item *ipa2;
1480 /* Handle an IPv4 wildcard */
1482 if (ipa->address[0] == 0)
1483 for (ipa2 = ipa; ipa2->next; ipa2 = ipa2->next)
1485 ip_address_item *ipa3 = ipa2->next;
1486 if (ipa3->address[0] == ':' &&
1487 ipa3->address[1] == 0 &&
1488 ipa3->port == ipa->port)
1490 ipa2->next = ipa3->next;
1497 /* Handle an IPv6 wildcard. */
1499 else if (ipa->address[0] == ':' && ipa->address[1] == 0)
1500 for (ipa2 = ipa; ipa2->next; ipa2 = ipa2->next)
1502 ip_address_item *ipa3 = ipa2->next;
1503 if (ipa3->address[0] == 0 && ipa3->port == ipa->port)
1505 ipa2->next = ipa3->next;
1506 ipa3->next = ipa->next;
1514 /* Get a vector to remember all the sockets in */
1516 for (ipa = addresses; ipa; ipa = ipa->next)
1517 listen_socket_count++;
1518 listen_sockets = store_get(sizeof(int) * listen_socket_count, FALSE);
1520 } /* daemon_listen but not inetd_wait_mode */
1522 if (f.daemon_listen)
1525 /* Do a sanity check on the max connects value just to save us from getting
1526 a huge amount of store. */
1528 if (smtp_accept_max > 4095) smtp_accept_max = 4096;
1530 /* There's no point setting smtp_accept_queue unless it is less than the max
1531 connects limit. The configuration reader ensures that the max is set if the
1532 queue-only option is set. */
1534 if (smtp_accept_queue > smtp_accept_max) smtp_accept_queue = 0;
1536 /* Get somewhere to keep the list of SMTP accepting pids if we are keeping
1537 track of them for total number and queue/host limits. */
1539 if (smtp_accept_max > 0)
1541 smtp_slots = store_get(smtp_accept_max * sizeof(smtp_slot), FALSE);
1542 for (int i = 0; i < smtp_accept_max; i++) smtp_slots[i] = empty_smtp_slot;
1546 /* The variable background_daemon is always false when debugging, but
1547 can also be forced false in order to keep a non-debugging daemon in the
1548 foreground. If background_daemon is true, close all open file descriptors that
1549 we know about, but then re-open stdin, stdout, and stderr to /dev/null. Also
1550 do this for inetd_wait mode.
1552 This is protection against any called functions (in libraries, or in
1553 Perl, or whatever) that think they can write to stderr (or stdout). Before this
1554 was added, it was quite likely that an SMTP connection would use one of these
1555 file descriptors, in which case writing random stuff to it caused chaos.
1557 Then disconnect from the controlling terminal, Most modern Unixes seem to have
1558 setsid() for getting rid of the controlling terminal. For any OS that doesn't,
1559 setsid() can be #defined as a no-op, or as something else. */
1561 if (f.background_daemon || f.inetd_wait_mode)
1563 log_close_all(); /* Just in case anything was logged earlier */
1564 search_tidyup(); /* Just in case any were used in reading the config. */
1565 (void)close(0); /* Get rid of stdin/stdout/stderr */
1568 exim_nullstd(); /* Connect stdin/stdout/stderr to /dev/null */
1569 log_stderr = NULL; /* So no attempt to copy paniclog output */
1572 if (f.background_daemon)
1574 /* If the parent process of this one has pid == 1, we are re-initializing the
1575 daemon as the result of a SIGHUP. In this case, there is no need to do
1576 anything, because the controlling terminal has long gone. Otherwise, fork, in
1577 case current process is a process group leader (see 'man setsid' for an
1578 explanation) before calling setsid(). */
1583 if (pid < 0) log_write(0, LOG_MAIN|LOG_PANIC_DIE,
1584 "fork() failed when starting daemon: %s", strerror(errno));
1585 if (pid > 0) exit(EXIT_SUCCESS); /* in parent process, just exit */
1586 (void)setsid(); /* release controlling terminal */
1590 /* We are now in the disconnected, daemon process (unless debugging). Set up
1591 the listening sockets if required. */
1593 daemon_notifier_socket();
1595 if (f.daemon_listen && !f.inetd_wait_mode)
1598 ip_address_item *ipa;
1600 /* For each IP address, create a socket, bind it to the appropriate port, and
1601 start listening. See comments above about IPv6 sockets that may or may not
1602 accept IPv4 calls when listening on all interfaces. We also have to cope with
1603 the case of a system with IPv6 libraries, but no IPv6 support in the kernel.
1604 listening, provided a wildcard IPv4 socket for the same port follows. */
1606 for (ipa = addresses, sk = 0; sk < listen_socket_count; ipa = ipa->next, sk++)
1609 ip_address_item *ipa2;
1612 if (Ustrchr(ipa->address, ':') != NULL)
1615 wildcard = ipa->address[1] == 0;
1620 wildcard = ipa->address[0] == 0;
1623 if ((listen_sockets[sk] = ip_socket(SOCK_STREAM, af)) < 0)
1625 if (check_special_case(0, addresses, ipa, FALSE))
1627 log_write(0, LOG_MAIN, "Failed to create IPv6 socket for wildcard "
1628 "listening (%s): will use IPv4", strerror(errno));
1631 log_write(0, LOG_PANIC_DIE, "IPv%c socket creation failed: %s",
1632 (af == AF_INET6)? '6' : '4', strerror(errno));
1635 /* If this is an IPv6 wildcard socket, set IPV6_V6ONLY if that option is
1636 available. Just log failure (can get protocol not available, just like
1637 socket creation can). */
1640 if (af == AF_INET6 && wildcard &&
1641 setsockopt(listen_sockets[sk], IPPROTO_IPV6, IPV6_V6ONLY, CS (&on),
1643 log_write(0, LOG_MAIN, "Setting IPV6_V6ONLY on daemon's IPv6 wildcard "
1644 "socket failed (%s): carrying on without it", strerror(errno));
1645 #endif /* IPV6_V6ONLY */
1647 /* Set SO_REUSEADDR so that the daemon can be restarted while a connection
1648 is being handled. Without this, a connection will prevent reuse of the
1649 smtp port for listening. */
1651 if (setsockopt(listen_sockets[sk], SOL_SOCKET, SO_REUSEADDR,
1652 US (&on), sizeof(on)) < 0)
1653 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "setting SO_REUSEADDR on socket "
1654 "failed when starting daemon: %s", strerror(errno));
1656 /* Set TCP_NODELAY; Exim does its own buffering. There is a switch to
1657 disable this because it breaks some broken clients. */
1659 if (tcp_nodelay) setsockopt(listen_sockets[sk], IPPROTO_TCP, TCP_NODELAY,
1660 US (&on), sizeof(on));
1662 /* Now bind the socket to the required port; if Exim is being restarted
1663 it may not always be possible to bind immediately, even with SO_REUSEADDR
1664 set, so try 10 times, waiting between each try. After 10 failures, we give
1665 up. In an IPv6 environment, if bind () fails with the error EADDRINUSE and
1666 we are doing wildcard IPv4 listening and there was a previous IPv6 wildcard
1667 address for the same port, ignore the error on the grounds that we must be
1668 in a system where the IPv6 socket accepts both kinds of call. This is
1669 necessary for (some release of) USAGI Linux; other IP stacks fail at the
1670 listen() stage instead. */
1673 f.tcp_fastopen_ok = TRUE;
1678 if (ip_bind(listen_sockets[sk], af, ipa->address, ipa->port) >= 0) break;
1679 if (check_special_case(errno, addresses, ipa, TRUE))
1681 DEBUG(D_any) debug_printf("wildcard IPv4 bind() failed after IPv6 "
1682 "listen() success; EADDRINUSE ignored\n");
1683 (void)close(listen_sockets[sk]);
1686 msg = US strerror(errno);
1692 if (daemon_startup_retries <= 0)
1693 log_write(0, LOG_MAIN|LOG_PANIC_DIE,
1694 "socket bind() to port %d for address %s failed: %s: "
1695 "daemon abandoned", ipa->port, addr, msg);
1696 log_write(0, LOG_MAIN, "socket bind() to port %d for address %s "
1697 "failed: %s: waiting %s before trying again (%d more %s)",
1698 ipa->port, addr, msg, readconf_printtime(daemon_startup_sleep),
1699 daemon_startup_retries, (daemon_startup_retries > 1)? "tries" : "try");
1700 daemon_startup_retries--;
1701 sleep(daemon_startup_sleep);
1706 debug_printf("listening on all interfaces (IPv%c) port %d\n",
1707 af == AF_INET6 ? '6' : '4', ipa->port);
1709 debug_printf("listening on %s port %d\n", ipa->address, ipa->port);
1711 #if defined(TCP_FASTOPEN) && !defined(__APPLE__)
1712 if ( f.tcp_fastopen_ok
1713 && setsockopt(listen_sockets[sk], IPPROTO_TCP, TCP_FASTOPEN,
1714 &smtp_connect_backlog, sizeof(smtp_connect_backlog)))
1716 DEBUG(D_any) debug_printf("setsockopt FASTOPEN: %s\n", strerror(errno));
1717 f.tcp_fastopen_ok = FALSE;
1721 /* Start listening on the bound socket, establishing the maximum backlog of
1722 connections that is allowed. On success, continue to the next address. */
1724 if (listen(listen_sockets[sk], smtp_connect_backlog) >= 0)
1726 #if defined(TCP_FASTOPEN) && defined(__APPLE__)
1727 if ( f.tcp_fastopen_ok
1728 && setsockopt(listen_sockets[sk], IPPROTO_TCP, TCP_FASTOPEN,
1731 DEBUG(D_any) debug_printf("setsockopt FASTOPEN: %s\n", strerror(errno));
1732 f.tcp_fastopen_ok = FALSE;
1738 /* Listening has failed. In an IPv6 environment, as for bind(), if listen()
1739 fails with the error EADDRINUSE and we are doing IPv4 wildcard listening
1740 and there was a previous successful IPv6 wildcard listen on the same port,
1741 we want to ignore the error on the grounds that we must be in a system
1742 where the IPv6 socket accepts both kinds of call. */
1744 if (!check_special_case(errno, addresses, ipa, TRUE))
1745 log_write(0, LOG_PANIC_DIE, "listen() failed on interface %s: %s",
1747 ? af == AF_INET6 ? US"(any IPv6)" : US"(any IPv4)" : ipa->address,
1750 DEBUG(D_any) debug_printf("wildcard IPv4 listen() failed after IPv6 "
1751 "listen() success; EADDRINUSE ignored\n");
1752 (void)close(listen_sockets[sk]);
1754 /* Come here if there has been a problem with the socket which we
1755 are going to ignore. We remove the address from the chain, and back up the
1759 sk--; /* Back up the count */
1760 listen_socket_count--; /* Reduce the total */
1761 if (ipa == addresses) addresses = ipa->next; else
1763 for (ipa2 = addresses; ipa2->next != ipa; ipa2 = ipa2->next);
1764 ipa2->next = ipa->next;
1767 } /* End of bind/listen loop for each address */
1768 } /* End of setup for listening */
1771 /* If we are not listening, we want to write a pid file only if -oP was
1772 explicitly given. */
1774 else if (!override_pid_file_path)
1777 /* Write the pid to a known file for assistance in identification, if required.
1778 We do this before giving up root privilege, because on some systems it is
1779 necessary to be root in order to write into the pid file directory. There's
1780 nothing to stop multiple daemons running, as long as no more than one listens
1781 on a given TCP/IP port on the same interface(s). However, in these
1782 circumstances it gets far too complicated to mess with pid file names
1783 automatically. Consequently, Exim 4 writes a pid file only
1785 (a) When running in the test harness, or
1786 (b) When -bd is used and -oX is not used, or
1787 (c) When -oP is used to supply a path.
1789 The variable daemon_write_pid is used to control this. */
1791 if (f.running_in_test_harness || write_pid)
1795 set_pid_file_path();
1796 if ((f = modefopen(pid_file_path, "wb", 0644)))
1798 (void)fprintf(f, "%d\n", (int)getpid());
1800 DEBUG(D_any) debug_printf("pid written to %s\n", pid_file_path);
1804 debug_printf("%s\n", string_open_failed(errno, "pid file %s",
1808 /* Set up the handler for SIGHUP, which causes a restart of the daemon. */
1810 sighup_seen = FALSE;
1811 signal(SIGHUP, sighup_handler);
1813 /* Give up root privilege at this point (assuming that exim_uid and exim_gid
1814 are not root). The third argument controls the running of initgroups().
1815 Normally we do this, in order to set up the groups for the Exim user. However,
1816 if we are not root at this time - some odd installations run that way - we
1819 exim_setugid(exim_uid, exim_gid, geteuid()==root_uid, US"running as a daemon");
1821 /* Update the originator_xxx fields so that received messages as listed as
1822 coming from Exim, not whoever started the daemon. */
1824 originator_uid = exim_uid;
1825 originator_gid = exim_gid;
1826 originator_login = (pw = getpwuid(exim_uid))
1827 ? string_copy_perm(US pw->pw_name, FALSE) : US"exim";
1829 /* Get somewhere to keep the list of queue-runner pids if we are keeping track
1830 of them (and also if we are doing queue runs). */
1832 if (queue_interval > 0 && local_queue_run_max > 0)
1834 queue_pid_slots = store_get(local_queue_run_max * sizeof(pid_t), FALSE);
1835 for (int i = 0; i < local_queue_run_max; i++) queue_pid_slots[i] = 0;
1838 /* Set up the handler for termination of child processes, and the one
1839 telling us to die. */
1841 sigchld_seen = FALSE;
1842 os_non_restarting_signal(SIGCHLD, main_sigchld_handler);
1844 sigterm_seen = FALSE;
1845 os_non_restarting_signal(SIGTERM, main_sigterm_handler);
1847 /* If we are to run the queue periodically, pretend the alarm has just gone
1848 off. This will cause the first queue-runner to get kicked off straight away. */
1850 sigalrm_seen = (queue_interval > 0);
1852 /* Log the start up of a daemon - at least one of listening or queue running
1855 if (f.inetd_wait_mode)
1857 uschar *p = big_buffer;
1859 if (inetd_wait_timeout >= 0)
1860 sprintf(CS p, "terminating after %d seconds", inetd_wait_timeout);
1862 sprintf(CS p, "with no wait timeout");
1864 log_write(0, LOG_MAIN,
1865 "exim %s daemon started: pid=%d, launched with listening socket, %s",
1866 version_string, getpid(), big_buffer);
1867 set_process_info("daemon(%s): pre-listening socket", version_string);
1869 /* set up the timeout logic */
1870 sigalrm_seen = TRUE;
1873 else if (f.daemon_listen)
1876 int smtps_ports = 0;
1877 ip_address_item * ipa;
1879 uschar * qinfo = queue_interval > 0
1880 ? string_sprintf("-q%s", readconf_printtime(queue_interval))
1881 : US"no queue runs";
1883 /* Build a list of listening addresses in big_buffer, but limit it to 10
1884 items. The style is for backwards compatibility.
1886 It is now possible to have some ports listening for SMTPS (the old,
1887 deprecated protocol that starts TLS without using STARTTLS), and others
1888 listening for standard SMTP. Keep their listings separate. */
1890 for (int j = 0, i; j < 2; j++)
1892 for (i = 0, ipa = addresses; i < 10 && ipa; i++, ipa = ipa->next)
1894 /* First time round, look for SMTP ports; second time round, look for
1895 SMTPS ports. Build IP+port strings. */
1897 if (host_is_tls_on_connect_port(ipa->port) == (j > 0))
1904 /* Now the information about the port (and sometimes interface) */
1906 if (ipa->address[0] == ':' && ipa->address[1] == 0)
1908 if (ipa->next && ipa->next->address[0] == 0 &&
1909 ipa->next->port == ipa->port)
1911 ipa->log = string_sprintf(" port %d (IPv6 and IPv4)", ipa->port);
1912 (ipa = ipa->next)->log = NULL;
1914 else if (ipa->v6_include_v4)
1915 ipa->log = string_sprintf(" port %d (IPv6 with IPv4)", ipa->port);
1917 ipa->log = string_sprintf(" port %d (IPv6)", ipa->port);
1919 else if (ipa->address[0] == 0) /* v4 wildcard */
1920 ipa->log = string_sprintf(" port %d (IPv4)", ipa->port);
1921 else /* check for previously-seen IP */
1923 ip_address_item * i2;
1924 for (i2 = addresses; i2 != ipa; i2 = i2->next)
1925 if ( host_is_tls_on_connect_port(i2->port) == (j > 0)
1926 && Ustrcmp(ipa->address, i2->address) == 0
1928 { /* found; append port to list */
1929 for (p = i2->log; *p; ) p++; /* end of existing string */
1930 if (*--p == '}') *p = '\0'; /* drop EOL */
1931 while (isdigit(*--p)) ; /* char before port */
1933 i2->log = *p == ':' /* no list yet? */
1934 ? string_sprintf("%.*s{%s,%d}",
1935 (int)(p - i2->log + 1), i2->log, p+1, ipa->port)
1936 : string_sprintf("%s,%d}", i2->log, ipa->port);
1940 if (i2 == ipa) /* first-time IP */
1941 ipa->log = string_sprintf(" [%s]:%d", ipa->address, ipa->port);
1948 for (int j = 0, i; j < 2; j++)
1950 /* First time round, look for SMTP ports; second time round, look for
1951 SMTPS ports. For the first one of each, insert leading text. */
1956 p += sprintf(CS p, "SMTP on");
1959 if (smtps_ports > 0)
1960 p += sprintf(CS p, "%sSMTPS on",
1961 smtp_ports == 0 ? "" : " and for ");
1963 /* Now the information about the port (and sometimes interface) */
1965 for (i = 0, ipa = addresses; i < 10 && ipa; i++, ipa = ipa->next)
1966 if (host_is_tls_on_connect_port(ipa->port) == (j > 0))
1968 p += sprintf(CS p, "%s", ipa->log);
1971 p += sprintf(CS p, " ...");
1974 log_write(0, LOG_MAIN,
1975 "exim %s daemon started: pid=%d, %s, listening for %s",
1976 version_string, getpid(), qinfo, big_buffer);
1977 set_process_info("daemon(%s): %s, listening for %s",
1978 version_string, qinfo, big_buffer);
1983 uschar * s = *queue_name
1984 ? string_sprintf("-qG%s/%s", queue_name, readconf_printtime(queue_interval))
1985 : string_sprintf("-q%s", readconf_printtime(queue_interval));
1986 log_write(0, LOG_MAIN,
1987 "exim %s daemon started: pid=%d, %s, not listening for SMTP",
1988 version_string, getpid(), s);
1989 set_process_info("daemon(%s): %s, not listening", version_string, s);
1992 /* Do any work it might be useful to amortize over our children
1993 (eg: compile regex) */
1996 smtp_deliver_init(); /* Used for callouts */
1998 #ifndef DISABLE_DKIM
2000 # ifdef MEASURE_TIMING
2002 gettimeofday(&t0, NULL);
2005 # ifdef MEASURE_TIMING
2006 report_time_since(&t0, US"dkim_exim_init (delta)");
2011 #ifdef WITH_CONTENT_SCAN
2018 /* Close the log so it can be renamed and moved. In the few cases below where
2019 this long-running process writes to the log (always exceptional conditions), it
2020 closes the log afterwards, for the same reason. */
2024 DEBUG(D_any) debug_print_ids(US"daemon running with");
2026 /* Any messages accepted via this route are going to be SMTP. */
2030 #ifdef MEASURE_TIMING
2031 report_time_since(×tamp_startup, US"daemon loop start"); /* testcase 0022 */
2034 /* Enter the never-ending loop... */
2039 struct sockaddr_in6 accepted;
2041 struct sockaddr_in accepted;
2048 daemon_die(); /* Does not return */
2050 /* This code is placed first in the loop, so that it gets obeyed at the
2051 start, before the first wait, for the queue-runner case, so that the first
2052 one can be started immediately.
2054 The other option is that we have an inetd wait timeout specified to -bw. */
2058 if (inetd_wait_timeout > 0)
2060 time_t resignal_interval = inetd_wait_timeout;
2062 if (last_connection_time == (time_t)0)
2065 debug_printf("inetd wait timeout expired, but still not seen first message, ignoring\n");
2069 time_t now = time(NULL);
2070 if (now == (time_t)-1)
2072 DEBUG(D_any) debug_printf("failed to get time: %s\n", strerror(errno));
2076 if ((now - last_connection_time) >= inetd_wait_timeout)
2079 debug_printf("inetd wait timeout %d expired, ending daemon\n",
2080 inetd_wait_timeout);
2081 log_write(0, LOG_MAIN, "exim %s daemon terminating, inetd wait timeout reached.\n",
2087 resignal_interval -= (now - last_connection_time);
2092 sigalrm_seen = FALSE;
2093 ALARM(resignal_interval);
2098 DEBUG(D_any) debug_printf("%s received\n",
2099 #ifdef EXPERIMENTAL_QUEUE_RAMP
2100 *queuerun_msgid ? "qrun notification" :
2104 /* Do a full queue run in a child process, if required, unless we already
2105 have enough queue runners on the go. If we are not running as root, a
2106 re-exec is required. */
2108 if (queue_interval > 0 &&
2109 (local_queue_run_max <= 0 || queue_run_count < local_queue_run_max))
2111 if ((pid = fork()) == 0)
2113 DEBUG(D_any) debug_printf("Starting queue-runner: pid %d\n",
2116 /* Disable debugging if it's required only for the daemon process. We
2117 leave the above message, because it ties up with the "child ended"
2118 debugging messages. */
2120 if (f.debug_daemon) debug_selector = 0;
2122 /* Close any open listening sockets in the child */
2124 if (daemon_notifier_fd >= 0)
2125 (void) close(daemon_notifier_fd);
2126 for (int sk = 0; sk < listen_socket_count; sk++)
2127 (void) close(listen_sockets[sk]);
2129 /* Reset SIGHUP and SIGCHLD in the child in both cases. */
2131 signal(SIGHUP, SIG_DFL);
2132 signal(SIGCHLD, SIG_DFL);
2133 signal(SIGTERM, SIG_DFL);
2135 /* Re-exec if privilege has been given up, unless deliver_drop_
2136 privilege is set. Reset SIGALRM before exec(). */
2138 if (geteuid() != root_uid && !deliver_drop_privilege)
2145 signal(SIGALRM, SIG_DFL);
2149 #ifdef EXPERIMENTAL_QUEUE_RAMP
2153 if (f.queue_run_first_delivery) *p++ = 'i';
2154 if (f.queue_run_force) *p++ = 'f';
2155 if (f.deliver_force_thaw) *p++ = 'f';
2156 if (f.queue_run_local) *p++ = 'l';
2158 extra[0] = *queue_name
2159 ? string_sprintf("%sG%s", opt, queue_name) : opt;
2161 #ifdef EXPERIMENTAL_QUEUE_RAMP
2162 if (*queuerun_msgid)
2164 extra[extracount++] = queuerun_msgid; /* Trigger only the */
2165 extra[extracount++] = queuerun_msgid; /* one message */
2169 /* If -R or -S were on the original command line, ensure they get
2172 if (deliver_selectstring)
2174 extra[extracount++] = f.deliver_selectstring_regex ? US"-Rr" : US"-R";
2175 extra[extracount++] = deliver_selectstring;
2178 if (deliver_selectstring_sender)
2180 extra[extracount++] = f.deliver_selectstring_sender_regex
2182 extra[extracount++] = deliver_selectstring_sender;
2185 /* Overlay this process with a new execution. */
2187 (void)child_exec_exim(CEE_EXEC_PANIC, FALSE, NULL, FALSE, extracount,
2188 extra[0], extra[1], extra[2], extra[3], extra[4], extra[5], extra[6]);
2190 /* Control never returns here. */
2193 /* No need to re-exec; SIGALRM remains set to the default handler */
2195 #ifdef EXPERIMENTAL_QUEUE_RAMP
2196 if (*queuerun_msgid)
2198 f.queue_2stage = FALSE;
2199 queue_run(queuerun_msgid, queuerun_msgid, FALSE);
2203 queue_run(NULL, NULL, FALSE);
2204 exim_underbar_exit(EXIT_SUCCESS);
2209 log_write(0, LOG_MAIN|LOG_PANIC, "daemon: fork of queue-runner "
2210 "process failed: %s", strerror(errno));
2215 for (int i = 0; i < local_queue_run_max; ++i)
2216 if (queue_pid_slots[i] <= 0)
2218 queue_pid_slots[i] = pid;
2222 DEBUG(D_any) debug_printf("%d queue-runner process%s running\n",
2223 queue_run_count, queue_run_count == 1 ? "" : "es");
2227 /* Reset the alarm clock */
2229 sigalrm_seen = FALSE;
2230 #ifdef EXPERIMENTAL_QUEUE_RAMP
2231 if (*queuerun_msgid)
2232 *queuerun_msgid = 0;
2235 ALARM(queue_interval);
2238 } /* sigalrm_seen */
2241 /* Sleep till a connection happens if listening, and handle the connection if
2242 that is why we woke up. The FreeBSD operating system requires the use of
2243 select() before accept() because the latter function is not interrupted by
2244 a signal, and we want to wake up for SIGCHLD and SIGALRM signals. Some other
2245 OS do notice signals in accept() but it does no harm to have the select()
2246 in for all of them - and it won't then be a lurking problem for ports to
2247 new OS. In fact, the later addition of listening on specific interfaces only
2248 requires this way of working anyway. */
2250 if (f.daemon_listen)
2252 int lcount, select_errno;
2254 BOOL select_failed = FALSE;
2255 fd_set select_listen;
2257 FD_ZERO(&select_listen);
2258 if (daemon_notifier_fd >= 0)
2259 FD_SET(daemon_notifier_fd, &select_listen);
2260 for (int sk = 0; sk < listen_socket_count; sk++)
2262 FD_SET(listen_sockets[sk], &select_listen);
2263 if (listen_sockets[sk] > max_socket) max_socket = listen_sockets[sk];
2266 DEBUG(D_any) debug_printf("Listening...\n");
2268 /* In rare cases we may have had a SIGCHLD signal in the time between
2269 setting the handler (below) and getting back here. If so, pretend that the
2270 select() was interrupted so that we reap the child. This might still leave
2271 a small window when a SIGCHLD could get lost. However, since we use SIGCHLD
2272 only to do the reaping more quickly, it shouldn't result in anything other
2273 than a delay until something else causes a wake-up. */
2281 lcount = select(max_socket + 1, (SELECT_ARG2_TYPE *)&select_listen,
2286 select_failed = TRUE;
2290 /* Clean up any subprocesses that may have terminated. We need to do this
2291 here so that smtp_accept_max_per_host works when a connection to that host
2292 has completed, and we are about to accept a new one. When this code was
2293 later in the sequence, a new connection could be rejected, even though an
2294 old one had just finished. Preserve the errno from any select() failure for
2295 the use of the common select/accept error processing below. */
2297 select_errno = errno;
2298 handle_ending_processes();
2299 errno = select_errno;
2302 /* Create or rotate any required keys */
2306 /* Loop for all the sockets that are currently ready to go. If select
2307 actually failed, we have set the count to 1 and select_failed=TRUE, so as
2308 to use the common error code for select/accept below. */
2310 while (lcount-- > 0)
2312 int accept_socket = -1;
2316 if ( daemon_notifier_fd >= 0
2317 && FD_ISSET(daemon_notifier_fd, &select_listen))
2319 FD_CLR(daemon_notifier_fd, &select_listen);
2320 sigalrm_seen = daemon_notification();
2321 break; /* to top of daemon loop */
2323 for (int sk = 0; sk < listen_socket_count; sk++)
2324 if (FD_ISSET(listen_sockets[sk], &select_listen))
2326 len = sizeof(accepted);
2327 accept_socket = accept(listen_sockets[sk],
2328 (struct sockaddr *)&accepted, &len);
2329 FD_CLR(listen_sockets[sk], &select_listen);
2334 /* If select or accept has failed and this was not caused by an
2335 interruption, log the incident and try again. With asymmetric TCP/IP
2336 routing errors such as "No route to network" have been seen here. Also
2337 "connection reset by peer" has been seen. These cannot be classed as
2338 disastrous errors, but they could fill up a lot of log. The code in smail
2339 crashes the daemon after 10 successive failures of accept, on the grounds
2340 that some OS fail continuously. Exim originally followed suit, but this
2341 appears to have caused problems. Now it just keeps going, but instead of
2342 logging each error, it batches them up when they are continuous. */
2344 if (accept_socket < 0 && errno != EINTR)
2346 if (accept_retry_count == 0)
2348 accept_retry_errno = errno;
2349 accept_retry_select_failed = select_failed;
2353 if (errno != accept_retry_errno ||
2354 select_failed != accept_retry_select_failed ||
2355 accept_retry_count >= 50)
2357 log_write(0, LOG_MAIN | ((accept_retry_count >= 50)? LOG_PANIC : 0),
2358 "%d %s() failure%s: %s",
2360 accept_retry_select_failed? "select" : "accept",
2361 (accept_retry_count == 1)? "" : "s",
2362 strerror(accept_retry_errno));
2364 accept_retry_count = 0;
2365 accept_retry_errno = errno;
2366 accept_retry_select_failed = select_failed;
2369 accept_retry_count++;
2374 if (accept_retry_count > 0)
2376 log_write(0, LOG_MAIN, "%d %s() failure%s: %s",
2378 accept_retry_select_failed? "select" : "accept",
2379 (accept_retry_count == 1)? "" : "s",
2380 strerror(accept_retry_errno));
2382 accept_retry_count = 0;
2386 /* If select/accept succeeded, deal with the connection. */
2388 if (accept_socket >= 0)
2390 if (inetd_wait_timeout)
2391 last_connection_time = time(NULL);
2392 handle_smtp_call(listen_sockets, listen_socket_count, accept_socket,
2393 (struct sockaddr *)&accepted);
2398 /* If not listening, then just sleep for the queue interval. If we woke
2399 up early the last time for some other signal, it won't matter because
2400 the alarm signal will wake at the right time. This code originally used
2401 sleep() but it turns out that on the FreeBSD system, sleep() is not inter-
2402 rupted by signals, so it wasn't waking up for SIGALRM or SIGCHLD. Luckily
2403 select() can be used as an interruptible sleep() on all versions of Unix. */
2408 tv.tv_sec = queue_interval;
2410 select(0, NULL, NULL, NULL, &tv);
2411 handle_ending_processes();
2414 /* Re-enable the SIGCHLD handler if it has been run. It can't do it
2415 for itself, because it isn't doing the waiting itself. */
2419 sigchld_seen = FALSE;
2420 os_non_restarting_signal(SIGCHLD, main_sigchld_handler);
2423 /* Handle being woken by SIGHUP. We know at this point that the result
2424 of accept() has been dealt with, so we can re-exec exim safely, first
2425 closing the listening sockets so that they can be reused. Cancel any pending
2426 alarm in case it is just about to go off, and set SIGHUP to be ignored so
2427 that another HUP in quick succession doesn't clobber the new daemon before it
2428 gets going. All log files get closed by the close-on-exec flag; however, if
2429 the exec fails, we need to close the logs. */
2433 log_write(0, LOG_MAIN, "pid %d: SIGHUP received: re-exec daemon",
2435 for (int sk = 0; sk < listen_socket_count; sk++)
2436 (void)close(listen_sockets[sk]);
2438 signal(SIGHUP, SIG_IGN);
2439 sighup_argv[0] = exim_path;
2441 execv(CS exim_path, (char *const *)sighup_argv);
2442 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "pid %d: exec of %s failed: %s",
2443 getpid(), exim_path, strerror(errno));
2447 } /* End of main loop */
2449 /* Control never reaches here */
2454 /* End of exim_daemon.c */