1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
5 /* Copyright (c) University of Cambridge 1995 - 2017 */
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 = { 0, NULL };
28 /*************************************************
29 * Local static variables *
30 *************************************************/
32 static SIGNAL_BOOL sigchld_seen;
33 static SIGNAL_BOOL sighup_seen;
35 static int accept_retry_count = 0;
36 static int accept_retry_errno;
37 static BOOL accept_retry_select_failed;
39 static int queue_run_count = 0;
40 static pid_t *queue_pid_slots = NULL;
41 static smtp_slot *smtp_slots = NULL;
43 static BOOL write_pid = TRUE;
47 /*************************************************
49 *************************************************/
51 /* All this handler does is to set a flag and re-enable the signal.
53 Argument: the signal number
58 sighup_handler(int sig)
60 sig = sig; /* Keep picky compilers happy */
62 signal(SIGHUP, sighup_handler);
67 /*************************************************
68 * SIGCHLD handler for main daemon process *
69 *************************************************/
71 /* Don't re-enable the handler here, since we aren't doing the
72 waiting here. If the signal is re-enabled, there will just be an
73 infinite sequence of calls to this handler. The SIGCHLD signal is
74 used just as a means of waking up the daemon so that it notices
75 terminated subprocesses as soon as possible.
77 Argument: the signal number
82 main_sigchld_handler(int sig)
84 sig = sig; /* Keep picky compilers happy */
85 os_non_restarting_signal(SIGCHLD, SIG_DFL);
92 /*************************************************
93 * Unexpected errors in SMTP calls *
94 *************************************************/
96 /* This function just saves a bit of repetitious coding.
99 log_msg Text of message to be logged
100 smtp_msg Text of SMTP error message
101 was_errno The failing errno
107 never_error(uschar *log_msg, uschar *smtp_msg, int was_errno)
109 uschar *emsg = (was_errno <= 0)? US"" :
110 string_sprintf(": %s", strerror(was_errno));
111 log_write(0, LOG_MAIN|LOG_PANIC, "%s%s", log_msg, emsg);
112 if (smtp_out != NULL) smtp_printf("421 %s\r\n", smtp_msg);
118 /*************************************************
119 * Handle a connected SMTP call *
120 *************************************************/
122 /* This function is called when an SMTP connection has been accepted.
123 If there are too many, give an error message and close down. Otherwise
124 spin off a sub-process to handle the call. The list of listening sockets
125 is required so that they can be closed in the sub-process. Take care not to
126 leak store in this process - reset the stacking pool at the end.
129 listen_sockets sockets which are listening for incoming calls
130 listen_socket_count count of listening sockets
131 accept_socket socket of the current accepted call
132 accepted socket information about the current call
138 handle_smtp_call(int *listen_sockets, int listen_socket_count,
139 int accept_socket, struct sockaddr *accepted)
142 union sockaddr_46 interface_sockaddr;
143 EXIM_SOCKLEN_T ifsize = sizeof(interface_sockaddr);
144 int dup_accept_socket = -1;
145 int max_for_this_host = 0;
148 int save_log_selector = *log_selector;
149 uschar *whofrom = NULL;
151 void *reset_point = store_get(0);
153 /* Make the address available in ASCII representation, and also fish out
156 sender_host_address = host_ntoa(-1, accepted, NULL, &sender_host_port);
157 DEBUG(D_any) debug_printf("Connection request from %s port %d\n",
158 sender_host_address, sender_host_port);
160 /* Set up the output stream, check the socket has duplicated, and set up the
161 input stream. These operations fail only the exceptional circumstances. Note
162 that never_error() won't use smtp_out if it is NULL. */
164 if (!(smtp_out = fdopen(accept_socket, "wb")))
166 never_error(US"daemon: fdopen() for smtp_out failed", US"", errno);
170 if ((dup_accept_socket = dup(accept_socket)) < 0)
172 never_error(US"daemon: couldn't dup socket descriptor",
173 US"Connection setup failed", errno);
177 if (!(smtp_in = fdopen(dup_accept_socket, "rb")))
179 never_error(US"daemon: fdopen() for smtp_in failed",
180 US"Connection setup failed", errno);
184 /* Get the data for the local interface address. Panic for most errors, but
185 "connection reset by peer" just means the connection went away. */
187 if (getsockname(accept_socket, (struct sockaddr *)(&interface_sockaddr),
190 log_write(0, LOG_MAIN | ((errno == ECONNRESET)? 0 : LOG_PANIC),
191 "getsockname() failed: %s", strerror(errno));
192 smtp_printf("421 Local problem: getsockname() failed; please try again later\r\n");
196 interface_address = host_ntoa(-1, &interface_sockaddr, NULL, &interface_port);
197 DEBUG(D_interface) debug_printf("interface address=%s port=%d\n",
198 interface_address, interface_port);
200 /* Build a string identifying the remote host and, if requested, the port and
201 the local interface data. This is for logging; at the end of this function the
202 memory is reclaimed. */
204 whofrom = string_append(whofrom, &wfsize, &wfptr, 3, "[", sender_host_address, "]");
206 if (LOGGING(incoming_port))
207 whofrom = string_append(whofrom, &wfsize, &wfptr, 2, ":", string_sprintf("%d",
210 if (LOGGING(incoming_interface))
211 whofrom = string_append(whofrom, &wfsize, &wfptr, 4, " I=[",
212 interface_address, "]:", string_sprintf("%d", interface_port));
214 whofrom[wfptr] = 0; /* Terminate the newly-built string */
216 /* Check maximum number of connections. We do not check for reserved
217 connections or unacceptable hosts here. That is done in the subprocess because
218 it might take some time. */
220 if (smtp_accept_max > 0 && smtp_accept_count >= smtp_accept_max)
222 DEBUG(D_any) debug_printf("rejecting SMTP connection: count=%d max=%d\n",
223 smtp_accept_count, smtp_accept_max);
224 smtp_printf("421 Too many concurrent SMTP connections; "
225 "please try again later.\r\n");
226 log_write(L_connection_reject,
227 LOG_MAIN, "Connection from %s refused: too many connections",
232 /* If a load limit above which only reserved hosts are acceptable is defined,
233 get the load average here, and if there are in fact no reserved hosts, do
234 the test right away (saves a fork). If there are hosts, do the check in the
235 subprocess because it might take time. */
237 if (smtp_load_reserve >= 0)
239 load_average = OS_GETLOADAVG();
240 if (smtp_reserve_hosts == NULL && load_average > smtp_load_reserve)
242 DEBUG(D_any) debug_printf("rejecting SMTP connection: load average = %.2f\n",
243 (double)load_average/1000.0);
244 smtp_printf("421 Too much load; please try again later.\r\n");
245 log_write(L_connection_reject,
246 LOG_MAIN, "Connection from %s refused: load average = %.2f",
247 whofrom, (double)load_average/1000.0);
252 /* Check that one specific host (strictly, IP address) is not hogging
253 resources. This is done here to prevent a denial of service attack by someone
254 forcing you to fork lots of times before denying service. The value of
255 smtp_accept_max_per_host is a string which is expanded. This makes it possible
256 to provide host-specific limits according to $sender_host address, but because
257 this is in the daemon mainline, only fast expansions (such as inline address
258 checks) should be used. The documentation is full of warnings. */
260 if (smtp_accept_max_per_host != NULL)
262 uschar *expanded = expand_string(smtp_accept_max_per_host);
263 if (expanded == NULL)
265 if (!expand_string_forcedfail)
266 log_write(0, LOG_MAIN|LOG_PANIC, "expansion of smtp_accept_max_per_host "
267 "failed for %s: %s", whofrom, expand_string_message);
269 /* For speed, interpret a decimal number inline here */
272 uschar *s = expanded;
274 max_for_this_host = max_for_this_host * 10 + *s++ - '0';
276 log_write(0, LOG_MAIN|LOG_PANIC, "expansion of smtp_accept_max_per_host "
277 "for %s contains non-digit: %s", whofrom, expanded);
281 /* If we have fewer connections than max_for_this_host, we can skip the tedious
282 per host_address checks. Note that at this stage smtp_accept_count contains the
283 count of *other* connections, not including this one. */
285 if ((max_for_this_host > 0) &&
286 (smtp_accept_count >= max_for_this_host))
289 int host_accept_count = 0;
290 int other_host_count = 0; /* keep a count of non matches to optimise */
292 for (i = 0; i < smtp_accept_max; ++i)
293 if (smtp_slots[i].host_address)
295 if (Ustrcmp(sender_host_address, smtp_slots[i].host_address) == 0)
300 /* Testing all these strings is expensive - see if we can drop out
301 early, either by hitting the target, or finding there are not enough
302 connections left to make the target. */
304 if ((host_accept_count >= max_for_this_host) ||
305 ((smtp_accept_count - other_host_count) < max_for_this_host))
309 if (host_accept_count >= max_for_this_host)
311 DEBUG(D_any) debug_printf("rejecting SMTP connection: too many from this "
312 "IP address: count=%d max=%d\n",
313 host_accept_count, max_for_this_host);
314 smtp_printf("421 Too many concurrent SMTP connections "
315 "from this IP address; please try again later.\r\n");
316 log_write(L_connection_reject,
317 LOG_MAIN, "Connection from %s refused: too many connections "
318 "from that IP address", whofrom);
323 /* OK, the connection count checks have been passed. Before we can fork the
324 accepting process, we must first log the connection if requested. This logging
325 used to happen in the subprocess, but doing that means that the value of
326 smtp_accept_count can be out of step by the time it is logged. So we have to do
327 the logging here and accept the performance cost. Note that smtp_accept_count
328 hasn't yet been incremented to take account of this connection.
330 In order to minimize the cost (because this is going to happen for every
331 connection), do a preliminary selector test here. This saves ploughing through
332 the generalized logging code each time when the selector is false. If the
333 selector is set, check whether the host is on the list for logging. If not,
334 arrange to unset the selector in the subprocess. */
336 if (LOGGING(smtp_connection))
338 uschar *list = hosts_connection_nolog;
339 memset(sender_host_cache, 0, sizeof(sender_host_cache));
340 if (list != NULL && verify_check_host(&list) == OK)
341 save_log_selector &= ~L_smtp_connection;
343 log_write(L_smtp_connection, LOG_MAIN, "SMTP connection from %s "
344 "(TCP/IP connection count = %d)", whofrom, smtp_accept_count + 1);
347 /* Now we can fork the accepting process; do a lookup tidy, just in case any
348 expansion above did a lookup. */
353 /* Handle the child process */
358 int queue_only_reason = 0;
359 int old_pool = store_pool;
360 int save_debug_selector = debug_selector;
361 BOOL local_queue_only;
362 BOOL session_local_queue_only;
364 struct sigaction act;
367 smtp_accept_count++; /* So that it includes this process */
369 /* May have been modified for the subprocess */
371 *log_selector = save_log_selector;
373 /* Get the local interface address into permanent store */
375 store_pool = POOL_PERM;
376 interface_address = string_copy(interface_address);
377 store_pool = old_pool;
379 /* Check for a tls-on-connect port */
381 if (host_is_tls_on_connect_port(interface_port)) tls_in.on_connect = TRUE;
383 /* Expand smtp_active_hostname if required. We do not do this any earlier,
384 because it may depend on the local interface address (indeed, that is most
385 likely what it depends on.) */
387 smtp_active_hostname = primary_hostname;
388 if (raw_active_hostname)
390 uschar * nah = expand_string(raw_active_hostname);
393 if (!expand_string_forcedfail)
395 log_write(0, LOG_MAIN|LOG_PANIC, "failed to expand \"%s\" "
396 "(smtp_active_hostname): %s", raw_active_hostname,
397 expand_string_message);
398 smtp_printf("421 Local configuration error; "
399 "please try again later.\r\n");
405 else if (*nah) smtp_active_hostname = nah;
408 /* Initialize the queueing flags */
411 session_local_queue_only = queue_only;
413 /* Close the listening sockets, and set the SIGCHLD handler to SIG_IGN.
414 We also attempt to set things up so that children are automatically reaped,
415 but just in case this isn't available, there's a paranoid waitpid() in the
416 loop too (except for systems where we are sure it isn't needed). See the more
417 extensive comment before the reception loop in exim.c for a fuller
418 explanation of this logic. */
420 for (i = 0; i < listen_socket_count; i++) (void)close(listen_sockets[i]);
422 /* Set FD_CLOEXEC on the SMTP socket. We don't want any rogue child processes
423 to be able to communicate with them, under any circumstances. */
424 (void)fcntl(accept_socket, F_SETFD,
425 fcntl(accept_socket, F_GETFD) | FD_CLOEXEC);
426 (void)fcntl(dup_accept_socket, F_SETFD,
427 fcntl(dup_accept_socket, F_GETFD) | FD_CLOEXEC);
430 act.sa_handler = SIG_IGN;
431 sigemptyset(&(act.sa_mask));
432 act.sa_flags = SA_NOCLDWAIT;
433 sigaction(SIGCHLD, &act, NULL);
435 signal(SIGCHLD, SIG_IGN);
438 /* Attempt to get an id from the sending machine via the RFC 1413
439 protocol. We do this in the sub-process in order not to hold up the
440 main process if there is any delay. Then set up the fullhost information
441 in case there is no HELO/EHLO.
443 If debugging is enabled only for the daemon, we must turn if off while
444 finding the id, but turn it on again afterwards so that information about the
445 incoming connection is output. */
447 if (debug_daemon) debug_selector = 0;
448 verify_get_ident(IDENT_PORT);
449 host_build_sender_fullhost();
450 debug_selector = save_debug_selector;
453 debug_printf("Process %d is handling incoming connection from %s\n",
454 (int)getpid(), sender_fullhost);
456 /* Now disable debugging permanently if it's required only for the daemon
459 if (debug_daemon) debug_selector = 0;
461 /* If there are too many child processes for immediate delivery,
462 set the session_local_queue_only flag, which is initialized from the
463 configured value and may therefore already be TRUE. Leave logging
464 till later so it will have a message id attached. Note that there is no
465 possibility of re-calculating this per-message, because the value of
466 smtp_accept_count does not change in this subprocess. */
468 if (smtp_accept_queue > 0 && smtp_accept_count > smtp_accept_queue)
470 session_local_queue_only = TRUE;
471 queue_only_reason = 1;
474 /* Handle the start of the SMTP session, then loop, accepting incoming
475 messages from the SMTP connection. The end will come at the QUIT command,
476 when smtp_setup_msg() returns 0. A break in the connection causes the
477 process to die (see accept.c).
479 NOTE: We do *not* call smtp_log_no_mail() if smtp_start_session() fails,
480 because a log line has already been written for all its failure exists
481 (usually "connection refused: <reason>") and writing another one is
482 unnecessary clutter. */
484 if (!smtp_start_session())
494 message_id[0] = 0; /* Clear out any previous message_id */
495 reset_point = store_get(0); /* Save current store high water point */
498 debug_printf("Process %d is ready for new message\n", (int)getpid());
500 /* Smtp_setup_msg() returns 0 on QUIT or if the call is from an
501 unacceptable host or if an ACL "drop" command was triggered, -1 on
502 connection lost, and +1 on validly reaching DATA. Receive_msg() almost
503 always returns TRUE when smtp_input is true; just retry if no message was
504 accepted (can happen for invalid message parameters). However, it can yield
505 FALSE if the connection was forcibly dropped by the DATA ACL. */
507 if ((rc = smtp_setup_msg()) > 0)
509 BOOL ok = receive_msg(FALSE);
510 search_tidyup(); /* Close cached databases */
511 if (!ok) /* Connection was dropped */
514 smtp_log_no_mail(); /* Log no mail if configured */
517 if (message_id[0] == 0) continue; /* No message was accepted */
523 int i, fd = fileno(smtp_in);
527 /* drain socket, for clean TCP FINs */
528 if (fcntl(fd, F_SETFL, O_NONBLOCK) == 0)
529 for(i = 16; read(fd, buf, sizeof(buf)) > 0 && i > 0; ) i--;
532 smtp_log_no_mail(); /* Log no mail if configured */
534 /*XXX should we pause briefly, hoping that the client will be the
535 active TCP closer hence get the TCP_WAIT endpoint? */
536 DEBUG(D_receive) debug_printf("SMTP>>(close on process exit)\n");
537 _exit(rc ? EXIT_FAILURE : EXIT_SUCCESS);
540 /* Show the recipients when debugging */
545 if (sender_address != NULL)
546 debug_printf("Sender: %s\n", sender_address);
547 if (recipients_list != NULL)
549 debug_printf("Recipients:\n");
550 for (i = 0; i < recipients_count; i++)
551 debug_printf(" %s\n", recipients_list[i].address);
555 /* A message has been accepted. Clean up any previous delivery processes
556 that have completed and are defunct, on systems where they don't go away
557 by themselves (see comments when setting SIG_IGN above). On such systems
558 (if any) these delivery processes hang around after termination until
559 the next message is received. */
561 #ifndef SIG_IGN_WORKS
562 while (waitpid(-1, NULL, WNOHANG) > 0);
565 /* Reclaim up the store used in accepting this message */
567 return_path = sender_address = NULL;
568 authenticated_sender = NULL;
569 sending_ip_address = NULL;
570 deliver_host_address = deliver_host =
571 deliver_domain_orig = deliver_localpart_orig = NULL;
572 dnslist_domain = dnslist_matched = NULL;
574 dkim_cur_signer = NULL;
576 store_reset(reset_point);
578 /* If queue_only is set or if there are too many incoming connections in
579 existence, session_local_queue_only will be TRUE. If it is not, check
580 whether we have received too many messages in this session for immediate
583 if (!session_local_queue_only &&
584 smtp_accept_queue_per_connection > 0 &&
585 receive_messagecount > smtp_accept_queue_per_connection)
587 session_local_queue_only = TRUE;
588 queue_only_reason = 2;
591 /* Initialize local_queue_only from session_local_queue_only. If it is not
592 true, and queue_only_load is set, check that the load average is below it.
593 If local_queue_only is set by this means, we also set if for the session if
594 queue_only_load_latch is true (the default). This means that, once set,
595 local_queue_only remains set for any subsequent messages on the same SMTP
596 connection. This is a deliberate choice; even though the load average may
597 fall, it doesn't seem right to deliver later messages on the same call when
598 not delivering earlier ones. However, the are special circumstances such as
599 very long-lived connections from scanning appliances where this is not the
600 best strategy. In such cases, queue_only_load_latch should be set false. */
602 if ( !(local_queue_only = session_local_queue_only)
603 && queue_only_load >= 0
604 && (local_queue_only = (load_average = OS_GETLOADAVG()) > queue_only_load)
607 queue_only_reason = 3;
608 if (queue_only_load_latch) session_local_queue_only = TRUE;
611 /* Log the queueing here, when it will get a message id attached, but
612 not if queue_only is set (case 0). */
614 if (local_queue_only) switch(queue_only_reason)
616 case 1: log_write(L_delay_delivery,
617 LOG_MAIN, "no immediate delivery: too many connections "
618 "(%d, max %d)", smtp_accept_count, smtp_accept_queue);
621 case 2: log_write(L_delay_delivery,
622 LOG_MAIN, "no immediate delivery: more than %d messages "
623 "received in one connection", smtp_accept_queue_per_connection);
626 case 3: log_write(L_delay_delivery,
627 LOG_MAIN, "no immediate delivery: load average %.2f",
628 (double)load_average/1000.0);
632 /* If a delivery attempt is required, spin off a new process to handle it.
633 If we are not root, we have to re-exec exim unless deliveries are being
634 done unprivileged. */
636 else if (!queue_only_policy && !deliver_freeze)
640 /* Before forking, ensure that the C output buffer is flushed. Otherwise
641 anything that it in it will get duplicated, leading to duplicate copies
642 of the pending output. */
646 if ((dpid = fork()) == 0)
648 (void)fclose(smtp_in);
649 (void)fclose(smtp_out);
651 /* Don't ever molest the parent's SSL connection, but do clean up
652 the data structures if necessary. */
655 tls_close(TRUE, FALSE);
658 /* Reset SIGHUP and SIGCHLD in the child in both cases. */
660 signal(SIGHUP, SIG_DFL);
661 signal(SIGCHLD, SIG_DFL);
663 if (geteuid() != root_uid && !deliver_drop_privilege)
665 signal(SIGALRM, SIG_DFL);
666 (void)child_exec_exim(CEE_EXEC_PANIC, FALSE, NULL, FALSE,
667 2, US"-Mc", message_id);
668 /* Control does not return here. */
671 /* No need to re-exec; SIGALRM remains set to the default handler */
673 (void)deliver_message(message_id, FALSE, FALSE);
680 DEBUG(D_any) debug_printf("forked delivery process %d\n", (int)dpid);
683 log_write(0, LOG_MAIN|LOG_PANIC, "daemon: delivery process fork "
684 "failed: %s", strerror(errno));
690 /* Carrying on in the parent daemon process... Can't do much if the fork
691 failed. Otherwise, keep count of the number of accepting processes and
692 remember the pid for ticking off when the child completes. */
695 never_error(US"daemon: accept process fork failed", US"Fork failed", errno);
699 for (i = 0; i < smtp_accept_max; ++i)
700 if (smtp_slots[i].pid <= 0)
702 smtp_slots[i].pid = pid;
703 if (smtp_accept_max_per_host != NULL)
704 smtp_slots[i].host_address = string_copy_malloc(sender_host_address);
708 DEBUG(D_any) debug_printf("%d SMTP accept process%s running\n",
709 smtp_accept_count, (smtp_accept_count == 1)? "" : "es");
712 /* Get here via goto in error cases */
716 /* Close the streams associated with the socket which will also close the
717 socket fds in this process. We can't do anything if fclose() fails, but
718 logging brings it to someone's attention. However, "connection reset by peer"
719 isn't really a problem, so skip that one. On Solaris, a dropped connection can
720 manifest itself as a broken pipe, so drop that one too. If the streams don't
721 exist, something went wrong while setting things up. Make sure the socket
722 descriptors are closed, in order to drop the connection. */
726 if (fclose(smtp_out) != 0 && errno != ECONNRESET && errno != EPIPE)
727 log_write(0, LOG_MAIN|LOG_PANIC, "daemon: fclose(smtp_out) failed: %s",
731 else (void)close(accept_socket);
735 if (fclose(smtp_in) != 0 && errno != ECONNRESET && errno != EPIPE)
736 log_write(0, LOG_MAIN|LOG_PANIC, "daemon: fclose(smtp_in) failed: %s",
740 else (void)close(dup_accept_socket);
742 /* Release any store used in this process, including the store used for holding
743 the incoming host address and an expanded active_hostname. */
747 sender_host_address = NULL;
748 store_reset(reset_point);
749 sender_host_address = NULL;
755 /*************************************************
756 * Check wildcard listen special cases *
757 *************************************************/
759 /* This function is used when binding and listening on lists of addresses and
760 ports. It tests for special cases of wildcard listening, when IPv4 and IPv6
761 sockets may interact in different ways in different operating systems. It is
762 passed an error number, the list of listening addresses, and the current
763 address. Two checks are available: for a previous wildcard IPv6 address, or for
764 a following wildcard IPv4 address, in both cases on the same port.
766 In practice, pairs of wildcard addresses should be adjacent in the address list
767 because they are sorted that way below.
771 addresses the list of addresses
772 ipa the current IP address
773 back if TRUE, check for previous wildcard IPv6 address
774 if FALSE, check for a following wildcard IPv4 address
776 Returns: TRUE or FALSE
780 check_special_case(int eno, ip_address_item *addresses, ip_address_item *ipa,
783 ip_address_item *ipa2;
785 /* For the "back" case, if the failure was "address in use" for a wildcard IPv4
786 address, seek a previous IPv6 wildcard address on the same port. As it is
787 previous, it must have been successfully bound and be listening. Flag it as a
788 "6 including 4" listener. */
792 if (eno != EADDRINUSE || ipa->address[0] != 0) return FALSE;
793 for (ipa2 = addresses; ipa2 != ipa; ipa2 = ipa2->next)
795 if (ipa2->address[1] == 0 && ipa2->port == ipa->port)
797 ipa2->v6_include_v4 = TRUE;
803 /* For the "forward" case, if the current address is a wildcard IPv6 address,
804 we seek a following wildcard IPv4 address on the same port. */
808 if (ipa->address[0] != ':' || ipa->address[1] != 0) return FALSE;
809 for (ipa2 = ipa->next; ipa2 != NULL; ipa2 = ipa2->next)
810 if (ipa2->address[0] == 0 && ipa->port == ipa2->port) return TRUE;
819 /*************************************************
820 * Handle terminating subprocesses *
821 *************************************************/
823 /* Handle the termination of child processes. Theoretically, this need be done
824 only when sigchld_seen is TRUE, but rumour has it that some systems lose
825 SIGCHLD signals at busy times, so to be on the safe side, this function is
826 called each time round. It shouldn't be too expensive.
833 handle_ending_processes(void)
838 while ((pid = waitpid(-1, &status, WNOHANG)) > 0)
843 debug_printf("child %d ended: status=0x%x\n", (int)pid, status);
845 if (WIFEXITED(status))
846 debug_printf(" normal exit, %d\n", WEXITSTATUS(status));
847 else if (WIFSIGNALED(status))
848 debug_printf(" signal exit, signal %d%s\n", WTERMSIG(status),
849 WCOREDUMP(status) ? " (core dumped)" : "");
853 /* If it's a listening daemon for which we are keeping track of individual
854 subprocesses, deal with an accepting process that has terminated. */
858 for (i = 0; i < smtp_accept_max; i++)
859 if (smtp_slots[i].pid == pid)
861 if (smtp_slots[i].host_address)
862 store_free(smtp_slots[i].host_address);
863 smtp_slots[i] = empty_smtp_slot;
864 if (--smtp_accept_count < 0) smtp_accept_count = 0;
865 DEBUG(D_any) debug_printf("%d SMTP accept process%s now running\n",
866 smtp_accept_count, (smtp_accept_count == 1)? "" : "es");
869 if (i < smtp_accept_max) continue; /* Found an accepting process */
872 /* If it wasn't an accepting process, see if it was a queue-runner
873 process that we are tracking. */
877 int max = atoi(CS expand_string(queue_run_max));
878 for (i = 0; i < max; i++)
879 if (queue_pid_slots[i] == pid)
881 queue_pid_slots[i] = 0;
882 if (--queue_run_count < 0) queue_run_count = 0;
883 DEBUG(D_any) debug_printf("%d queue-runner process%s now running\n",
884 queue_run_count, (queue_run_count == 1)? "" : "es");
893 /*************************************************
894 * Exim Daemon Mainline *
895 *************************************************/
897 /* The daemon can do two jobs, either of which is optional:
899 (1) Listens for incoming SMTP calls and spawns off a sub-process to handle
900 each one. This is requested by the -bd option, with -oX specifying the SMTP
901 port on which to listen (for testing).
903 (2) Spawns a queue-running process every so often. This is controlled by the
904 -q option with a an interval time. (If no time is given, a single queue run
905 is done from the main function, and control doesn't get here.)
907 Root privilege is required in order to attach to port 25. Some systems require
908 it when calling socket() rather than bind(). To cope with all cases, we run as
909 root for both socket() and bind(). Some systems also require root in order to
910 write to the pid file directory. This function must therefore be called as root
911 if it is to work properly in all circumstances. Once the socket is bound and
912 the pid file written, root privilege is given up if there is an exim uid.
914 There are no arguments to this function, and it never returns. */
920 int *listen_sockets = NULL;
921 int listen_socket_count = 0;
922 ip_address_item *addresses = NULL;
923 time_t last_connection_time = (time_t)0;
924 int local_queue_run_max = atoi(CS expand_string(queue_run_max));
926 /* If any debugging options are set, turn on the D_pid bit so that all
927 debugging lines get the pid added. */
929 DEBUG(D_any|D_v) debug_selector |= D_pid;
933 listen_socket_count = 1;
934 listen_sockets = store_get(sizeof(int));
936 if (dup2(0, 3) == -1)
937 log_write(0, LOG_MAIN|LOG_PANIC_DIE,
938 "failed to dup inetd socket safely away: %s", strerror(errno));
940 listen_sockets[0] = 3;
946 if (debug_file == stderr)
948 /* need a call to log_write before call to open debug_file, so that
949 log.c:file_path has been initialised. This is unfortunate. */
950 log_write(0, LOG_MAIN, "debugging Exim in inetd wait mode starting");
954 exim_nullstd(); /* re-open fd2 after we just closed it again */
955 debug_logging_activate(US"-wait", NULL);
958 DEBUG(D_any) debug_printf("running in inetd wait mode\n");
960 /* As per below, when creating sockets ourselves, we handle tcp_nodelay for
961 our own buffering; we assume though that inetd set the socket REUSEADDR. */
964 if (setsockopt(3, IPPROTO_TCP, TCP_NODELAY, US &on, sizeof(on)))
965 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "failed to set socket NODELAY: %s",
970 if (inetd_wait_mode || daemon_listen)
972 /* If any option requiring a load average to be available during the
973 reception of a message is set, call os_getloadavg() while we are root
974 for those OS for which this is necessary the first time it is called (in
975 order to perform an "open" on the kernel memory file). */
977 #ifdef LOAD_AVG_NEEDS_ROOT
978 if (queue_only_load >= 0 || smtp_load_reserve >= 0 ||
979 (deliver_queue_load_max >= 0 && deliver_drop_privilege))
980 (void)os_getloadavg();
985 /* Do the preparation for setting up a listener on one or more interfaces, and
986 possible on various ports. This is controlled by the combination of
987 local_interfaces (which can set IP addresses and ports) and daemon_smtp_port
988 (which is a list of default ports to use for those items in local_interfaces
989 that do not specify a port). The -oX command line option can be used to
990 override one or both of these options.
992 If local_interfaces is not set, the default is to listen on all interfaces.
993 When it is set, it can include "all IPvx interfaces" as an item. This is useful
994 when different ports are in use.
996 It turns out that listening on all interfaces is messy in an IPv6 world,
997 because several different implementation approaches have been taken. This code
998 is now supposed to work with all of them. The point of difference is whether an
999 IPv6 socket that is listening on all interfaces will receive incoming IPv4
1000 calls or not. We also have to cope with the case when IPv6 libraries exist, but
1001 there is no IPv6 support in the kernel.
1003 . On Solaris, an IPv6 socket will accept IPv4 calls, and give them as mapped
1004 addresses. However, if an IPv4 socket is also listening on all interfaces,
1005 calls are directed to the appropriate socket.
1007 . On (some versions of) Linux, an IPv6 socket will accept IPv4 calls, and
1008 give them as mapped addresses, but an attempt also to listen on an IPv4
1009 socket on all interfaces causes an error.
1011 . On OpenBSD, an IPv6 socket will not accept IPv4 calls. You have to set up
1012 two sockets if you want to accept both kinds of call.
1014 . FreeBSD is like OpenBSD, but it has the IPV6_V6ONLY socket option, which
1015 can be turned off, to make it behave like the versions of Linux described
1018 . I heard a report that the USAGI IPv6 stack for Linux has implemented
1021 So, what we do when IPv6 is supported is as follows:
1023 (1) After it is set up, the list of interfaces is scanned for wildcard
1024 addresses. If an IPv6 and an IPv4 wildcard are both found for the same
1025 port, the list is re-arranged so that they are together, with the IPv6
1028 (2) If the creation of a wildcard IPv6 socket fails, we just log the error and
1029 carry on if an IPv4 wildcard socket for the same port follows later in the
1030 list. This allows Exim to carry on in the case when the kernel has no IPv6
1033 (3) Having created an IPv6 wildcard socket, we try to set IPV6_V6ONLY if that
1034 option is defined. However, if setting fails, carry on regardless (but log
1037 (4) If binding or listening on an IPv6 wildcard socket fails, it is a serious
1040 (5) If binding or listening on an IPv4 wildcard socket fails with the error
1041 EADDRINUSE, and a previous interface was an IPv6 wildcard for the same
1042 port (which must have succeeded or we wouldn't have got this far), we
1043 assume we are in the situation where just a single socket is permitted,
1044 and ignore the error.
1048 The preparation code decodes options and sets up the relevant data. We do this
1049 first, so that we can return non-zero if there are any syntax errors, and also
1052 if (daemon_listen && !inetd_wait_mode)
1054 int *default_smtp_port;
1058 const uschar * list;
1059 uschar *local_iface_source = US"local_interfaces";
1060 ip_address_item *ipa;
1061 ip_address_item **pipa;
1063 /* If -oX was used, disable the writing of a pid file unless -oP was
1064 explicitly used to force it. Then scan the string given to -oX. Any items
1065 that contain neither a dot nor a colon are used to override daemon_smtp_port.
1066 Any other items are used to override local_interfaces. */
1068 if (override_local_interfaces != NULL)
1070 uschar *new_smtp_port = NULL;
1071 uschar *new_local_interfaces = NULL;
1077 if (override_pid_file_path == NULL) write_pid = FALSE;
1079 list = override_local_interfaces;
1081 while ((s = string_nextinlist(&list, &sep, big_buffer, big_buffer_size)))
1088 if (Ustrpbrk(s, ".:") == NULL)
1090 ptr = &new_smtp_port;
1091 sizeptr = &portsize;
1096 ptr = &new_local_interfaces;
1097 sizeptr = &ifacesize;
1105 *ptr = string_catn(*ptr, sizeptr, ptrptr, US"<", 1);
1108 *ptr = string_catn(*ptr, sizeptr, ptrptr, joinstr, 2);
1109 *ptr = string_cat (*ptr, sizeptr, ptrptr, s);
1112 if (new_smtp_port != NULL)
1114 new_smtp_port[portptr] = 0;
1115 daemon_smtp_port = new_smtp_port;
1116 DEBUG(D_any) debug_printf("daemon_smtp_port overridden by -oX:\n %s\n",
1120 if (new_local_interfaces != NULL)
1122 new_local_interfaces[ifaceptr] = 0;
1123 local_interfaces = new_local_interfaces;
1124 local_iface_source = US"-oX data";
1125 DEBUG(D_any) debug_printf("local_interfaces overridden by -oX:\n %s\n",
1130 /* Create a list of default SMTP ports, to be used if local_interfaces
1131 contains entries without explicit ports. First count the number of ports, then
1132 build a translated list in a vector. */
1134 list = daemon_smtp_port;
1136 while ((s = string_nextinlist(&list, &sep, big_buffer, big_buffer_size)))
1138 default_smtp_port = store_get((pct+1) * sizeof(int));
1139 list = daemon_smtp_port;
1142 (s = string_nextinlist(&list, &sep, big_buffer, big_buffer_size));
1148 default_smtp_port[pct] = Ustrtol(s, &end, 0);
1149 if (end != s + Ustrlen(s))
1150 log_write(0, LOG_PANIC_DIE|LOG_CONFIG, "invalid SMTP port: %s", s);
1154 struct servent *smtp_service = getservbyname(CS s, "tcp");
1156 log_write(0, LOG_PANIC_DIE|LOG_CONFIG, "TCP port \"%s\" not found", s);
1157 default_smtp_port[pct] = ntohs(smtp_service->s_port);
1160 default_smtp_port[pct] = 0;
1162 /* Check the list of TLS-on-connect ports and do name lookups if needed */
1164 list = tls_in.on_connect_ports;
1166 while ((s = string_nextinlist(&list, &sep, big_buffer, big_buffer_size)))
1169 list = tls_in.on_connect_ports;
1170 tls_in.on_connect_ports = NULL;
1172 while ((s = string_nextinlist(&list, &sep, big_buffer, big_buffer_size)))
1176 struct servent *smtp_service = getservbyname(CS s, "tcp");
1178 log_write(0, LOG_PANIC_DIE|LOG_CONFIG, "TCP port \"%s\" not found", s);
1179 s= string_sprintf("%d", (int)ntohs(smtp_service->s_port));
1181 tls_in.on_connect_ports = string_append_listele(tls_in.on_connect_ports,
1187 /* Create the list of local interfaces, possibly with ports included. This
1188 list may contain references to 0.0.0.0 and ::0 as wildcards. These special
1189 values are converted below. */
1191 addresses = host_build_ifacelist(local_interfaces, local_iface_source);
1193 /* In the list of IP addresses, convert 0.0.0.0 into an empty string, and ::0
1194 into the string ":". We use these to recognize wildcards in IPv4 and IPv6. In
1195 fact, many IP stacks recognize 0.0.0.0 and ::0 and handle them as wildcards
1196 anyway, but we need to know which are the wildcard addresses, and the shorter
1199 In the same scan, fill in missing port numbers from the default list. When
1200 there is more than one item in the list, extra items are created. */
1202 for (ipa = addresses; ipa != NULL; ipa = ipa->next)
1206 if (Ustrcmp(ipa->address, "0.0.0.0") == 0) ipa->address[0] = 0;
1207 else if (Ustrcmp(ipa->address, "::0") == 0)
1209 ipa->address[0] = ':';
1210 ipa->address[1] = 0;
1213 if (ipa->port > 0) continue;
1215 if (daemon_smtp_port[0] <= 0)
1216 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "no port specified for interface "
1217 "%s and daemon_smtp_port is unset; cannot start daemon",
1218 (ipa->address[0] == 0)? US"\"all IPv4\"" :
1219 (ipa->address[1] == 0)? US"\"all IPv6\"" : ipa->address);
1220 ipa->port = default_smtp_port[0];
1221 for (i = 1; default_smtp_port[i] > 0; i++)
1223 ip_address_item *new = store_get(sizeof(ip_address_item));
1224 memcpy(new->address, ipa->address, Ustrlen(ipa->address) + 1);
1225 new->port = default_smtp_port[i];
1226 new->next = ipa->next;
1232 /* Scan the list of addresses for wildcards. If we find an IPv4 and an IPv6
1233 wildcard for the same port, ensure that (a) they are together and (b) the
1234 IPv6 address comes first. This makes handling the messy features easier, and
1235 also simplifies the construction of the "daemon started" log line. */
1238 for (ipa = addresses; ipa != NULL; pipa = &(ipa->next), ipa = ipa->next)
1240 ip_address_item *ipa2;
1242 /* Handle an IPv4 wildcard */
1244 if (ipa->address[0] == 0)
1246 for (ipa2 = ipa; ipa2->next != NULL; ipa2 = ipa2->next)
1248 ip_address_item *ipa3 = ipa2->next;
1249 if (ipa3->address[0] == ':' &&
1250 ipa3->address[1] == 0 &&
1251 ipa3->port == ipa->port)
1253 ipa2->next = ipa3->next;
1261 /* Handle an IPv6 wildcard. */
1263 else if (ipa->address[0] == ':' && ipa->address[1] == 0)
1265 for (ipa2 = ipa; ipa2->next != NULL; ipa2 = ipa2->next)
1267 ip_address_item *ipa3 = ipa2->next;
1268 if (ipa3->address[0] == 0 && ipa3->port == ipa->port)
1270 ipa2->next = ipa3->next;
1271 ipa3->next = ipa->next;
1280 /* Get a vector to remember all the sockets in */
1282 for (ipa = addresses; ipa != NULL; ipa = ipa->next)
1283 listen_socket_count++;
1284 listen_sockets = store_get(sizeof(int) * listen_socket_count);
1286 } /* daemon_listen but not inetd_wait_mode */
1291 /* Do a sanity check on the max connects value just to save us from getting
1292 a huge amount of store. */
1294 if (smtp_accept_max > 4095) smtp_accept_max = 4096;
1296 /* There's no point setting smtp_accept_queue unless it is less than the max
1297 connects limit. The configuration reader ensures that the max is set if the
1298 queue-only option is set. */
1300 if (smtp_accept_queue > smtp_accept_max) smtp_accept_queue = 0;
1302 /* Get somewhere to keep the list of SMTP accepting pids if we are keeping
1303 track of them for total number and queue/host limits. */
1305 if (smtp_accept_max > 0)
1308 smtp_slots = store_get(smtp_accept_max * sizeof(smtp_slot));
1309 for (i = 0; i < smtp_accept_max; i++) smtp_slots[i] = empty_smtp_slot;
1313 /* The variable background_daemon is always false when debugging, but
1314 can also be forced false in order to keep a non-debugging daemon in the
1315 foreground. If background_daemon is true, close all open file descriptors that
1316 we know about, but then re-open stdin, stdout, and stderr to /dev/null. Also
1317 do this for inetd_wait mode.
1319 This is protection against any called functions (in libraries, or in
1320 Perl, or whatever) that think they can write to stderr (or stdout). Before this
1321 was added, it was quite likely that an SMTP connection would use one of these
1322 file descriptors, in which case writing random stuff to it caused chaos.
1324 Then disconnect from the controlling terminal, Most modern Unixes seem to have
1325 setsid() for getting rid of the controlling terminal. For any OS that doesn't,
1326 setsid() can be #defined as a no-op, or as something else. */
1328 if (background_daemon || inetd_wait_mode)
1330 log_close_all(); /* Just in case anything was logged earlier */
1331 search_tidyup(); /* Just in case any were used in reading the config. */
1332 (void)close(0); /* Get rid of stdin/stdout/stderr */
1335 exim_nullstd(); /* Connect stdin/stdout/stderr to /dev/null */
1336 log_stderr = NULL; /* So no attempt to copy paniclog output */
1339 if (background_daemon)
1341 /* If the parent process of this one has pid == 1, we are re-initializing the
1342 daemon as the result of a SIGHUP. In this case, there is no need to do
1343 anything, because the controlling terminal has long gone. Otherwise, fork, in
1344 case current process is a process group leader (see 'man setsid' for an
1345 explanation) before calling setsid(). */
1350 if (pid < 0) log_write(0, LOG_MAIN|LOG_PANIC_DIE,
1351 "fork() failed when starting daemon: %s", strerror(errno));
1352 if (pid > 0) exit(EXIT_SUCCESS); /* in parent process, just exit */
1353 (void)setsid(); /* release controlling terminal */
1357 /* We are now in the disconnected, daemon process (unless debugging). Set up
1358 the listening sockets if required. */
1360 if (daemon_listen && !inetd_wait_mode)
1363 ip_address_item *ipa;
1365 /* For each IP address, create a socket, bind it to the appropriate port, and
1366 start listening. See comments above about IPv6 sockets that may or may not
1367 accept IPv4 calls when listening on all interfaces. We also have to cope with
1368 the case of a system with IPv6 libraries, but no IPv6 support in the kernel.
1369 listening, provided a wildcard IPv4 socket for the same port follows. */
1371 for (ipa = addresses, sk = 0; sk < listen_socket_count; ipa = ipa->next, sk++)
1374 ip_address_item *ipa2;
1377 if (Ustrchr(ipa->address, ':') != NULL)
1380 wildcard = ipa->address[1] == 0;
1385 wildcard = ipa->address[0] == 0;
1388 if ((listen_sockets[sk] = ip_socket(SOCK_STREAM, af)) < 0)
1390 if (check_special_case(0, addresses, ipa, FALSE))
1392 log_write(0, LOG_MAIN, "Failed to create IPv6 socket for wildcard "
1393 "listening (%s): will use IPv4", strerror(errno));
1396 log_write(0, LOG_PANIC_DIE, "IPv%c socket creation failed: %s",
1397 (af == AF_INET6)? '6' : '4', strerror(errno));
1400 /* If this is an IPv6 wildcard socket, set IPV6_V6ONLY if that option is
1401 available. Just log failure (can get protocol not available, just like
1402 socket creation can). */
1405 if (af == AF_INET6 && wildcard &&
1406 setsockopt(listen_sockets[sk], IPPROTO_IPV6, IPV6_V6ONLY, (char *)(&on),
1408 log_write(0, LOG_MAIN, "Setting IPV6_V6ONLY on daemon's IPv6 wildcard "
1409 "socket failed (%s): carrying on without it", strerror(errno));
1410 #endif /* IPV6_V6ONLY */
1412 /* Set SO_REUSEADDR so that the daemon can be restarted while a connection
1413 is being handled. Without this, a connection will prevent reuse of the
1414 smtp port for listening. */
1416 if (setsockopt(listen_sockets[sk], SOL_SOCKET, SO_REUSEADDR,
1417 (uschar *)(&on), sizeof(on)) < 0)
1418 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "setting SO_REUSEADDR on socket "
1419 "failed when starting daemon: %s", strerror(errno));
1421 /* Set TCP_NODELAY; Exim does its own buffering. There is a switch to
1422 disable this because it breaks some broken clients. */
1424 if (tcp_nodelay) setsockopt(listen_sockets[sk], IPPROTO_TCP, TCP_NODELAY,
1425 (uschar *)(&on), sizeof(on));
1427 /* Now bind the socket to the required port; if Exim is being restarted
1428 it may not always be possible to bind immediately, even with SO_REUSEADDR
1429 set, so try 10 times, waiting between each try. After 10 failures, we give
1430 up. In an IPv6 environment, if bind () fails with the error EADDRINUSE and
1431 we are doing wildcard IPv4 listening and there was a previous IPv6 wildcard
1432 address for the same port, ignore the error on the grounds that we must be
1433 in a system where the IPv6 socket accepts both kinds of call. This is
1434 necessary for (some release of) USAGI Linux; other IP stacks fail at the
1435 listen() stage instead. */
1438 tcp_fastopen_ok = TRUE;
1443 if (ip_bind(listen_sockets[sk], af, ipa->address, ipa->port) >= 0) break;
1444 if (check_special_case(errno, addresses, ipa, TRUE))
1446 DEBUG(D_any) debug_printf("wildcard IPv4 bind() failed after IPv6 "
1447 "listen() success; EADDRINUSE ignored\n");
1448 (void)close(listen_sockets[sk]);
1451 msg = US strerror(errno);
1452 addr = wildcard? ((af == AF_INET6)? US"(any IPv6)" : US"(any IPv4)") :
1454 if (daemon_startup_retries <= 0)
1455 log_write(0, LOG_MAIN|LOG_PANIC_DIE,
1456 "socket bind() to port %d for address %s failed: %s: "
1457 "daemon abandoned", ipa->port, addr, msg);
1458 log_write(0, LOG_MAIN, "socket bind() to port %d for address %s "
1459 "failed: %s: waiting %s before trying again (%d more %s)",
1460 ipa->port, addr, msg, readconf_printtime(daemon_startup_sleep),
1461 daemon_startup_retries, (daemon_startup_retries > 1)? "tries" : "try");
1462 daemon_startup_retries--;
1463 sleep(daemon_startup_sleep);
1468 debug_printf("listening on all interfaces (IPv%c) port %d\n",
1469 af == AF_INET6 ? '6' : '4', ipa->port);
1471 debug_printf("listening on %s port %d\n", ipa->address, ipa->port);
1474 if (setsockopt(listen_sockets[sk], IPPROTO_TCP, TCP_FASTOPEN,
1475 &smtp_connect_backlog, sizeof(smtp_connect_backlog)))
1477 DEBUG(D_any) debug_printf("setsockopt FASTOPEN: %s\n", strerror(errno));
1478 tcp_fastopen_ok = FALSE;
1482 /* Start listening on the bound socket, establishing the maximum backlog of
1483 connections that is allowed. On success, continue to the next address. */
1485 if (listen(listen_sockets[sk], smtp_connect_backlog) >= 0) continue;
1487 /* Listening has failed. In an IPv6 environment, as for bind(), if listen()
1488 fails with the error EADDRINUSE and we are doing IPv4 wildcard listening
1489 and there was a previous successful IPv6 wildcard listen on the same port,
1490 we want to ignore the error on the grounds that we must be in a system
1491 where the IPv6 socket accepts both kinds of call. */
1493 if (!check_special_case(errno, addresses, ipa, TRUE))
1494 log_write(0, LOG_PANIC_DIE, "listen() failed on interface %s: %s",
1496 ? af == AF_INET6 ? US"(any IPv6)" : US"(any IPv4)" : ipa->address,
1499 DEBUG(D_any) debug_printf("wildcard IPv4 listen() failed after IPv6 "
1500 "listen() success; EADDRINUSE ignored\n");
1501 (void)close(listen_sockets[sk]);
1503 /* Come here if there has been a problem with the socket which we
1504 are going to ignore. We remove the address from the chain, and back up the
1508 sk--; /* Back up the count */
1509 listen_socket_count--; /* Reduce the total */
1510 if (ipa == addresses) addresses = ipa->next; else
1512 for (ipa2 = addresses; ipa2->next != ipa; ipa2 = ipa2->next);
1513 ipa2->next = ipa->next;
1516 } /* End of bind/listen loop for each address */
1517 } /* End of setup for listening */
1520 /* If we are not listening, we want to write a pid file only if -oP was
1521 explicitly given. */
1523 else if (override_pid_file_path == NULL) write_pid = FALSE;
1525 /* Write the pid to a known file for assistance in identification, if required.
1526 We do this before giving up root privilege, because on some systems it is
1527 necessary to be root in order to write into the pid file directory. There's
1528 nothing to stop multiple daemons running, as long as no more than one listens
1529 on a given TCP/IP port on the same interface(s). However, in these
1530 circumstances it gets far too complicated to mess with pid file names
1531 automatically. Consequently, Exim 4 writes a pid file only
1533 (a) When running in the test harness, or
1534 (b) When -bd is used and -oX is not used, or
1535 (c) When -oP is used to supply a path.
1537 The variable daemon_write_pid is used to control this. */
1539 if (running_in_test_harness || write_pid)
1543 if (override_pid_file_path != NULL)
1544 pid_file_path = override_pid_file_path;
1546 if (pid_file_path[0] == 0)
1547 pid_file_path = string_sprintf("%s/exim-daemon.pid", spool_directory);
1549 f = modefopen(pid_file_path, "wb", 0644);
1552 (void)fprintf(f, "%d\n", (int)getpid());
1554 DEBUG(D_any) debug_printf("pid written to %s\n", pid_file_path);
1559 debug_printf("%s\n", string_open_failed(errno, "pid file %s",
1564 /* Set up the handler for SIGHUP, which causes a restart of the daemon. */
1566 sighup_seen = FALSE;
1567 signal(SIGHUP, sighup_handler);
1569 /* Give up root privilege at this point (assuming that exim_uid and exim_gid
1570 are not root). The third argument controls the running of initgroups().
1571 Normally we do this, in order to set up the groups for the Exim user. However,
1572 if we are not root at this time - some odd installations run that way - we
1575 exim_setugid(exim_uid, exim_gid, geteuid()==root_uid, US"running as a daemon");
1577 /* Update the originator_xxx fields so that received messages as listed as
1578 coming from Exim, not whoever started the daemon. */
1580 originator_uid = exim_uid;
1581 originator_gid = exim_gid;
1582 originator_login = ((pw = getpwuid(exim_uid)) != NULL)?
1583 string_copy_malloc(US pw->pw_name) : US"exim";
1585 /* Get somewhere to keep the list of queue-runner pids if we are keeping track
1586 of them (and also if we are doing queue runs). */
1588 if (queue_interval > 0 && local_queue_run_max > 0)
1591 queue_pid_slots = store_get(local_queue_run_max * sizeof(pid_t));
1592 for (i = 0; i < local_queue_run_max; i++) queue_pid_slots[i] = 0;
1595 /* Set up the handler for termination of child processes. */
1597 sigchld_seen = FALSE;
1598 os_non_restarting_signal(SIGCHLD, main_sigchld_handler);
1600 /* If we are to run the queue periodically, pretend the alarm has just gone
1601 off. This will cause the first queue-runner to get kicked off straight away. */
1603 sigalrm_seen = (queue_interval > 0);
1605 /* Log the start up of a daemon - at least one of listening or queue running
1608 if (inetd_wait_mode)
1610 uschar *p = big_buffer;
1612 if (inetd_wait_timeout >= 0)
1613 sprintf(CS p, "terminating after %d seconds", inetd_wait_timeout);
1615 sprintf(CS p, "with no wait timeout");
1617 log_write(0, LOG_MAIN,
1618 "exim %s daemon started: pid=%d, launched with listening socket, %s",
1619 version_string, getpid(), big_buffer);
1620 set_process_info("daemon(%s): pre-listening socket", version_string);
1622 /* set up the timeout logic */
1626 else if (daemon_listen)
1630 int smtps_ports = 0;
1631 ip_address_item * ipa;
1632 uschar * p = big_buffer;
1633 uschar * qinfo = queue_interval > 0
1634 ? string_sprintf("-q%s", readconf_printtime(queue_interval))
1635 : US"no queue runs";
1637 /* Build a list of listening addresses in big_buffer, but limit it to 10
1638 items. The style is for backwards compatibility.
1640 It is now possible to have some ports listening for SMTPS (the old,
1641 deprecated protocol that starts TLS without using STARTTLS), and others
1642 listening for standard SMTP. Keep their listings separate. */
1644 for (j = 0; j < 2; j++)
1646 for (i = 0, ipa = addresses; i < 10 && ipa; i++, ipa = ipa->next)
1648 /* First time round, look for SMTP ports; second time round, look for
1649 SMTPS ports. For the first one of each, insert leading text. */
1651 if (host_is_tls_on_connect_port(ipa->port) == (j > 0))
1655 if (smtp_ports++ == 0)
1657 memcpy(p, "SMTP on", 8);
1663 if (smtps_ports++ == 0)
1665 (void)sprintf(CS p, "%sSMTPS on",
1666 smtp_ports == 0 ? "" : " and for ");
1671 /* Now the information about the port (and sometimes interface) */
1673 if (ipa->address[0] == ':' && ipa->address[1] == 0)
1675 if (ipa->next != NULL && ipa->next->address[0] == 0 &&
1676 ipa->next->port == ipa->port)
1678 (void)sprintf(CS p, " port %d (IPv6 and IPv4)", ipa->port);
1681 else if (ipa->v6_include_v4)
1682 (void)sprintf(CS p, " port %d (IPv6 with IPv4)", ipa->port);
1684 (void)sprintf(CS p, " port %d (IPv6)", ipa->port);
1686 else if (ipa->address[0] == 0)
1687 (void)sprintf(CS p, " port %d (IPv4)", ipa->port);
1689 (void)sprintf(CS p, " [%s]:%d", ipa->address, ipa->port);
1690 while (*p != 0) p++;
1696 memcpy(p, " ...", 5);
1701 log_write(0, LOG_MAIN,
1702 "exim %s daemon started: pid=%d, %s, listening for %s",
1703 version_string, getpid(), qinfo, big_buffer);
1704 set_process_info("daemon(%s): %s, listening for %s",
1705 version_string, qinfo, big_buffer);
1710 uschar * s = *queue_name
1711 ? string_sprintf("-qG%s/%s", queue_name, readconf_printtime(queue_interval))
1712 : string_sprintf("-q%s", readconf_printtime(queue_interval));
1713 log_write(0, LOG_MAIN,
1714 "exim %s daemon started: pid=%d, %s, not listening for SMTP",
1715 version_string, getpid(), s);
1716 set_process_info("daemon(%s): %s, not listening", version_string, s);
1719 /* Do any work it might be useful to amortize over our children
1720 (eg: compile regex) */
1724 #ifdef WITH_CONTENT_SCAN
1728 /* Close the log so it can be renamed and moved. In the few cases below where
1729 this long-running process writes to the log (always exceptional conditions), it
1730 closes the log afterwards, for the same reason. */
1734 DEBUG(D_any) debug_print_ids(US"daemon running with");
1736 /* Any messages accepted via this route are going to be SMTP. */
1740 /* Enter the never-ending loop... */
1745 struct sockaddr_in6 accepted;
1747 struct sockaddr_in accepted;
1753 /* This code is placed first in the loop, so that it gets obeyed at the
1754 start, before the first wait, for the queue-runner case, so that the first
1755 one can be started immediately.
1757 The other option is that we have an inetd wait timeout specified to -bw. */
1761 if (inetd_wait_timeout > 0)
1763 time_t resignal_interval = inetd_wait_timeout;
1765 if (last_connection_time == (time_t)0)
1768 debug_printf("inetd wait timeout expired, but still not seen first message, ignoring\n");
1772 time_t now = time(NULL);
1773 if (now == (time_t)-1)
1775 DEBUG(D_any) debug_printf("failed to get time: %s\n", strerror(errno));
1779 if ((now - last_connection_time) >= inetd_wait_timeout)
1782 debug_printf("inetd wait timeout %d expired, ending daemon\n",
1783 inetd_wait_timeout);
1784 log_write(0, LOG_MAIN, "exim %s daemon terminating, inetd wait timeout reached.\n",
1790 resignal_interval -= (now - last_connection_time);
1795 sigalrm_seen = FALSE;
1796 alarm(resignal_interval);
1801 DEBUG(D_any) debug_printf("SIGALRM received\n");
1803 /* Do a full queue run in a child process, if required, unless we already
1804 have enough queue runners on the go. If we are not running as root, a
1805 re-exec is required. */
1807 if (queue_interval > 0 &&
1808 (local_queue_run_max <= 0 || queue_run_count < local_queue_run_max))
1810 if ((pid = fork()) == 0)
1814 DEBUG(D_any) debug_printf("Starting queue-runner: pid %d\n",
1817 /* Disable debugging if it's required only for the daemon process. We
1818 leave the above message, because it ties up with the "child ended"
1819 debugging messages. */
1821 if (debug_daemon) debug_selector = 0;
1823 /* Close any open listening sockets in the child */
1825 for (sk = 0; sk < listen_socket_count; sk++)
1826 (void)close(listen_sockets[sk]);
1828 /* Reset SIGHUP and SIGCHLD in the child in both cases. */
1830 signal(SIGHUP, SIG_DFL);
1831 signal(SIGCHLD, SIG_DFL);
1833 /* Re-exec if privilege has been given up, unless deliver_drop_
1834 privilege is set. Reset SIGALRM before exec(). */
1836 if (geteuid() != root_uid && !deliver_drop_privilege)
1843 signal(SIGALRM, SIG_DFL);
1846 if (queue_2stage) *p++ = 'q';
1847 if (queue_run_first_delivery) *p++ = 'i';
1848 if (queue_run_force) *p++ = 'f';
1849 if (deliver_force_thaw) *p++ = 'f';
1850 if (queue_run_local) *p++ = 'l';
1852 extra[0] = queue_name
1853 ? string_sprintf("%sG%s", opt, queue_name) : opt;
1855 /* If -R or -S were on the original command line, ensure they get
1858 if (deliver_selectstring)
1860 extra[extracount++] = deliver_selectstring_regex ? US"-Rr" : US"-R";
1861 extra[extracount++] = deliver_selectstring;
1864 if (deliver_selectstring_sender)
1866 extra[extracount++] = deliver_selectstring_sender_regex
1868 extra[extracount++] = deliver_selectstring_sender;
1871 /* Overlay this process with a new execution. */
1873 (void)child_exec_exim(CEE_EXEC_PANIC, FALSE, NULL, TRUE, extracount,
1874 extra[0], extra[1], extra[2], extra[3], extra[4]);
1876 /* Control never returns here. */
1879 /* No need to re-exec; SIGALRM remains set to the default handler */
1881 queue_run(NULL, NULL, FALSE);
1882 _exit(EXIT_SUCCESS);
1887 log_write(0, LOG_MAIN|LOG_PANIC, "daemon: fork of queue-runner "
1888 "process failed: %s", strerror(errno));
1894 for (i = 0; i < local_queue_run_max; ++i)
1895 if (queue_pid_slots[i] <= 0)
1897 queue_pid_slots[i] = pid;
1901 DEBUG(D_any) debug_printf("%d queue-runner process%s running\n",
1902 queue_run_count, (queue_run_count == 1)? "" : "es");
1906 /* Reset the alarm clock */
1908 sigalrm_seen = FALSE;
1909 alarm(queue_interval);
1912 } /* sigalrm_seen */
1915 /* Sleep till a connection happens if listening, and handle the connection if
1916 that is why we woke up. The FreeBSD operating system requires the use of
1917 select() before accept() because the latter function is not interrupted by
1918 a signal, and we want to wake up for SIGCHLD and SIGALRM signals. Some other
1919 OS do notice signals in accept() but it does no harm to have the select()
1920 in for all of them - and it won't then be a lurking problem for ports to
1921 new OS. In fact, the later addition of listening on specific interfaces only
1922 requires this way of working anyway. */
1926 int sk, lcount, select_errno;
1928 BOOL select_failed = FALSE;
1929 fd_set select_listen;
1931 FD_ZERO(&select_listen);
1932 for (sk = 0; sk < listen_socket_count; sk++)
1934 FD_SET(listen_sockets[sk], &select_listen);
1935 if (listen_sockets[sk] > max_socket) max_socket = listen_sockets[sk];
1938 DEBUG(D_any) debug_printf("Listening...\n");
1940 /* In rare cases we may have had a SIGCHLD signal in the time between
1941 setting the handler (below) and getting back here. If so, pretend that the
1942 select() was interrupted so that we reap the child. This might still leave
1943 a small window when a SIGCHLD could get lost. However, since we use SIGCHLD
1944 only to do the reaping more quickly, it shouldn't result in anything other
1945 than a delay until something else causes a wake-up. */
1954 lcount = select(max_socket + 1, (SELECT_ARG2_TYPE *)&select_listen,
1960 select_failed = TRUE;
1964 /* Clean up any subprocesses that may have terminated. We need to do this
1965 here so that smtp_accept_max_per_host works when a connection to that host
1966 has completed, and we are about to accept a new one. When this code was
1967 later in the sequence, a new connection could be rejected, even though an
1968 old one had just finished. Preserve the errno from any select() failure for
1969 the use of the common select/accept error processing below. */
1971 select_errno = errno;
1972 handle_ending_processes();
1973 errno = select_errno;
1975 /* Loop for all the sockets that are currently ready to go. If select
1976 actually failed, we have set the count to 1 and select_failed=TRUE, so as
1977 to use the common error code for select/accept below. */
1979 while (lcount-- > 0)
1981 int accept_socket = -1;
1984 for (sk = 0; sk < listen_socket_count; sk++)
1986 if (FD_ISSET(listen_sockets[sk], &select_listen))
1988 len = sizeof(accepted);
1989 accept_socket = accept(listen_sockets[sk],
1990 (struct sockaddr *)&accepted, &len);
1991 FD_CLR(listen_sockets[sk], &select_listen);
1997 /* If select or accept has failed and this was not caused by an
1998 interruption, log the incident and try again. With asymmetric TCP/IP
1999 routing errors such as "No route to network" have been seen here. Also
2000 "connection reset by peer" has been seen. These cannot be classed as
2001 disastrous errors, but they could fill up a lot of log. The code in smail
2002 crashes the daemon after 10 successive failures of accept, on the grounds
2003 that some OS fail continuously. Exim originally followed suit, but this
2004 appears to have caused problems. Now it just keeps going, but instead of
2005 logging each error, it batches them up when they are continuous. */
2007 if (accept_socket < 0 && errno != EINTR)
2009 if (accept_retry_count == 0)
2011 accept_retry_errno = errno;
2012 accept_retry_select_failed = select_failed;
2016 if (errno != accept_retry_errno ||
2017 select_failed != accept_retry_select_failed ||
2018 accept_retry_count >= 50)
2020 log_write(0, LOG_MAIN | ((accept_retry_count >= 50)? LOG_PANIC : 0),
2021 "%d %s() failure%s: %s",
2023 accept_retry_select_failed? "select" : "accept",
2024 (accept_retry_count == 1)? "" : "s",
2025 strerror(accept_retry_errno));
2027 accept_retry_count = 0;
2028 accept_retry_errno = errno;
2029 accept_retry_select_failed = select_failed;
2032 accept_retry_count++;
2037 if (accept_retry_count > 0)
2039 log_write(0, LOG_MAIN, "%d %s() failure%s: %s",
2041 accept_retry_select_failed? "select" : "accept",
2042 (accept_retry_count == 1)? "" : "s",
2043 strerror(accept_retry_errno));
2045 accept_retry_count = 0;
2049 /* If select/accept succeeded, deal with the connection. */
2051 if (accept_socket >= 0)
2053 if (inetd_wait_timeout)
2054 last_connection_time = time(NULL);
2055 handle_smtp_call(listen_sockets, listen_socket_count, accept_socket,
2056 (struct sockaddr *)&accepted);
2061 /* If not listening, then just sleep for the queue interval. If we woke
2062 up early the last time for some other signal, it won't matter because
2063 the alarm signal will wake at the right time. This code originally used
2064 sleep() but it turns out that on the FreeBSD system, sleep() is not inter-
2065 rupted by signals, so it wasn't waking up for SIGALRM or SIGCHLD. Luckily
2066 select() can be used as an interruptible sleep() on all versions of Unix. */
2071 tv.tv_sec = queue_interval;
2073 select(0, NULL, NULL, NULL, &tv);
2074 handle_ending_processes();
2077 /* Re-enable the SIGCHLD handler if it has been run. It can't do it
2078 for itself, because it isn't doing the waiting itself. */
2082 sigchld_seen = FALSE;
2083 os_non_restarting_signal(SIGCHLD, main_sigchld_handler);
2086 /* Handle being woken by SIGHUP. We know at this point that the result
2087 of accept() has been dealt with, so we can re-exec exim safely, first
2088 closing the listening sockets so that they can be reused. Cancel any pending
2089 alarm in case it is just about to go off, and set SIGHUP to be ignored so
2090 that another HUP in quick succession doesn't clobber the new daemon before it
2091 gets going. All log files get closed by the close-on-exec flag; however, if
2092 the exec fails, we need to close the logs. */
2097 log_write(0, LOG_MAIN, "pid %d: SIGHUP received: re-exec daemon",
2099 for (sk = 0; sk < listen_socket_count; sk++)
2100 (void)close(listen_sockets[sk]);
2102 signal(SIGHUP, SIG_IGN);
2103 sighup_argv[0] = exim_path;
2105 execv(CS exim_path, (char *const *)sighup_argv);
2106 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "pid %d: exec of %s failed: %s",
2107 getpid(), exim_path, strerror(errno));
2111 } /* End of main loop */
2113 /* Control never reaches here */
2118 /* End of exim_daemon.c */