1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
5 /* Copyright (c) University of Cambridge 1995 - 2014 */
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 assigments 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 use_log_write_selector = log_write_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 smtp_out = fdopen(accept_socket, "wb");
165 if (smtp_out == NULL)
167 never_error(US"daemon: fdopen() for smtp_out failed", US"", errno);
171 dup_accept_socket = dup(accept_socket);
172 if (dup_accept_socket < 0)
174 never_error(US"daemon: couldn't dup socket descriptor",
175 US"Connection setup failed", errno);
179 smtp_in = fdopen(dup_accept_socket, "rb");
182 never_error(US"daemon: fdopen() for smtp_in failed",
183 US"Connection setup failed", errno);
187 /* Get the data for the local interface address. Panic for most errors, but
188 "connection reset by peer" just means the connection went away. */
190 if (getsockname(accept_socket, (struct sockaddr *)(&interface_sockaddr),
193 log_write(0, LOG_MAIN | ((errno == ECONNRESET)? 0 : LOG_PANIC),
194 "getsockname() failed: %s", strerror(errno));
195 smtp_printf("421 Local problem: getsockname() failed; please try again later\r\n");
199 interface_address = host_ntoa(-1, &interface_sockaddr, NULL, &interface_port);
200 DEBUG(D_interface) debug_printf("interface address=%s port=%d\n",
201 interface_address, interface_port);
203 /* Build a string identifying the remote host and, if requested, the port and
204 the local interface data. This is for logging; at the end of this function the
205 memory is reclaimed. */
207 whofrom = string_append(whofrom, &wfsize, &wfptr, 3, "[", sender_host_address, "]");
209 if ((log_extra_selector & LX_incoming_port) != 0)
210 whofrom = string_append(whofrom, &wfsize, &wfptr, 2, ":", string_sprintf("%d",
213 if ((log_extra_selector & LX_incoming_interface) != 0)
214 whofrom = string_append(whofrom, &wfsize, &wfptr, 4, " I=[",
215 interface_address, "]:", string_sprintf("%d", interface_port));
217 whofrom[wfptr] = 0; /* Terminate the newly-built string */
219 /* Check maximum number of connections. We do not check for reserved
220 connections or unacceptable hosts here. That is done in the subprocess because
221 it might take some time. */
223 if (smtp_accept_max > 0 && smtp_accept_count >= smtp_accept_max)
225 DEBUG(D_any) debug_printf("rejecting SMTP connection: count=%d max=%d\n",
226 smtp_accept_count, smtp_accept_max);
227 smtp_printf("421 Too many concurrent SMTP connections; "
228 "please try again later.\r\n");
229 log_write(L_connection_reject,
230 LOG_MAIN, "Connection from %s refused: too many connections",
235 /* If a load limit above which only reserved hosts are acceptable is defined,
236 get the load average here, and if there are in fact no reserved hosts, do
237 the test right away (saves a fork). If there are hosts, do the check in the
238 subprocess because it might take time. */
240 if (smtp_load_reserve >= 0)
242 load_average = OS_GETLOADAVG();
243 if (smtp_reserve_hosts == NULL && load_average > smtp_load_reserve)
245 DEBUG(D_any) debug_printf("rejecting SMTP connection: load average = %.2f\n",
246 (double)load_average/1000.0);
247 smtp_printf("421 Too much load; please try again later.\r\n");
248 log_write(L_connection_reject,
249 LOG_MAIN, "Connection from %s refused: load average = %.2f",
250 whofrom, (double)load_average/1000.0);
255 /* Check that one specific host (strictly, IP address) is not hogging
256 resources. This is done here to prevent a denial of service attack by someone
257 forcing you to fork lots of times before denying service. The value of
258 smtp_accept_max_per_host is a string which is expanded. This makes it possible
259 to provide host-specific limits according to $sender_host address, but because
260 this is in the daemon mainline, only fast expansions (such as inline address
261 checks) should be used. The documentation is full of warnings. */
263 if (smtp_accept_max_per_host != NULL)
265 uschar *expanded = expand_string(smtp_accept_max_per_host);
266 if (expanded == NULL)
268 if (!expand_string_forcedfail)
269 log_write(0, LOG_MAIN|LOG_PANIC, "expansion of smtp_accept_max_per_host "
270 "failed for %s: %s", whofrom, expand_string_message);
272 /* For speed, interpret a decimal number inline here */
275 uschar *s = expanded;
277 max_for_this_host = max_for_this_host * 10 + *s++ - '0';
279 log_write(0, LOG_MAIN|LOG_PANIC, "expansion of smtp_accept_max_per_host "
280 "for %s contains non-digit: %s", whofrom, expanded);
284 /* If we have fewer connections than max_for_this_host, we can skip the tedious
285 per host_address checks. Note that at this stage smtp_accept_count contains the
286 count of *other* connections, not including this one. */
288 if ((max_for_this_host > 0) &&
289 (smtp_accept_count >= max_for_this_host))
292 int host_accept_count = 0;
293 int other_host_count = 0; /* keep a count of non matches to optimise */
295 for (i = 0; i < smtp_accept_max; ++i)
297 if (smtp_slots[i].host_address != NULL)
299 if (Ustrcmp(sender_host_address, smtp_slots[i].host_address) == 0)
304 /* Testing all these strings is expensive - see if we can drop out
305 early, either by hitting the target, or finding there are not enough
306 connections left to make the target. */
308 if ((host_accept_count >= max_for_this_host) ||
309 ((smtp_accept_count - other_host_count) < max_for_this_host))
314 if (host_accept_count >= max_for_this_host)
316 DEBUG(D_any) debug_printf("rejecting SMTP connection: too many from this "
317 "IP address: count=%d max=%d\n",
318 host_accept_count, max_for_this_host);
319 smtp_printf("421 Too many concurrent SMTP connections "
320 "from this IP address; please try again later.\r\n");
321 log_write(L_connection_reject,
322 LOG_MAIN, "Connection from %s refused: too many connections "
323 "from that IP address", whofrom);
328 /* OK, the connection count checks have been passed. Before we can fork the
329 accepting process, we must first log the connection if requested. This logging
330 used to happen in the subprocess, but doing that means that the value of
331 smtp_accept_count can be out of step by the time it is logged. So we have to do
332 the logging here and accept the performance cost. Note that smtp_accept_count
333 hasn't yet been incremented to take account of this connection.
335 In order to minimize the cost (because this is going to happen for every
336 connection), do a preliminary selector test here. This saves ploughing through
337 the generalized logging code each time when the selector is false. If the
338 selector is set, check whether the host is on the list for logging. If not,
339 arrange to unset the selector in the subprocess. */
341 if ((log_write_selector & L_smtp_connection) != 0)
343 uschar *list = hosts_connection_nolog;
344 if (list != NULL && verify_check_host(&list) == OK)
345 use_log_write_selector &= ~L_smtp_connection;
347 log_write(L_smtp_connection, LOG_MAIN, "SMTP connection from %s "
348 "(TCP/IP connection count = %d)", whofrom, smtp_accept_count + 1);
351 /* Now we can fork the accepting process; do a lookup tidy, just in case any
352 expansion above did a lookup. */
357 /* Handle the child process */
362 int queue_only_reason = 0;
363 int old_pool = store_pool;
364 int save_debug_selector = debug_selector;
365 BOOL local_queue_only;
366 BOOL session_local_queue_only;
368 struct sigaction act;
371 smtp_accept_count++; /* So that it includes this process */
373 /* May have been modified for the subprocess */
375 log_write_selector = use_log_write_selector;
377 /* Get the local interface address into permanent store */
379 store_pool = POOL_PERM;
380 interface_address = string_copy(interface_address);
381 store_pool = old_pool;
383 /* Check for a tls-on-connect port */
385 if (host_is_tls_on_connect_port(interface_port)) tls_in.on_connect = TRUE;
387 /* Expand smtp_active_hostname if required. We do not do this any earlier,
388 because it may depend on the local interface address (indeed, that is most
389 likely what it depends on.) */
391 smtp_active_hostname = primary_hostname;
392 if (raw_active_hostname != NULL)
394 uschar *nah = expand_string(raw_active_hostname);
397 if (!expand_string_forcedfail)
399 log_write(0, LOG_MAIN|LOG_PANIC, "failed to expand \"%s\" "
400 "(smtp_active_hostname): %s", raw_active_hostname,
401 expand_string_message);
402 smtp_printf("421 Local configuration error; "
403 "please try again later.\r\n");
409 else if (nah[0] != 0) smtp_active_hostname = nah;
412 /* Initialize the queueing flags */
415 session_local_queue_only = queue_only;
417 /* Close the listening sockets, and set the SIGCHLD handler to SIG_IGN.
418 We also attempt to set things up so that children are automatically reaped,
419 but just in case this isn't available, there's a paranoid waitpid() in the
420 loop too (except for systems where we are sure it isn't needed). See the more
421 extensive comment before the reception loop in exim.c for a fuller
422 explanation of this logic. */
424 for (i = 0; i < listen_socket_count; i++) (void)close(listen_sockets[i]);
426 /* Set FD_CLOEXEC on the SMTP socket. We don't want any rogue child processes
427 to be able to communicate with them, under any circumstances. */
428 (void)fcntl(accept_socket, F_SETFD,
429 fcntl(accept_socket, F_GETFD) | FD_CLOEXEC);
430 (void)fcntl(dup_accept_socket, F_SETFD,
431 fcntl(dup_accept_socket, F_GETFD) | FD_CLOEXEC);
434 act.sa_handler = SIG_IGN;
435 sigemptyset(&(act.sa_mask));
436 act.sa_flags = SA_NOCLDWAIT;
437 sigaction(SIGCHLD, &act, NULL);
439 signal(SIGCHLD, SIG_IGN);
442 /* Attempt to get an id from the sending machine via the RFC 1413
443 protocol. We do this in the sub-process in order not to hold up the
444 main process if there is any delay. Then set up the fullhost information
445 in case there is no HELO/EHLO.
447 If debugging is enabled only for the daemon, we must turn if off while
448 finding the id, but turn it on again afterwards so that information about the
449 incoming connection is output. */
451 if (debug_daemon) debug_selector = 0;
452 verify_get_ident(IDENT_PORT);
453 host_build_sender_fullhost();
454 debug_selector = save_debug_selector;
457 debug_printf("Process %d is handling incoming connection from %s\n",
458 (int)getpid(), sender_fullhost);
460 /* Now disable debugging permanently if it's required only for the daemon
463 if (debug_daemon) debug_selector = 0;
465 /* If there are too many child processes for immediate delivery,
466 set the session_local_queue_only flag, which is initialized from the
467 configured value and may therefore already be TRUE. Leave logging
468 till later so it will have a message id attached. Note that there is no
469 possibility of re-calculating this per-message, because the value of
470 smtp_accept_count does not change in this subprocess. */
472 if (smtp_accept_queue > 0 && smtp_accept_count > smtp_accept_queue)
474 session_local_queue_only = TRUE;
475 queue_only_reason = 1;
478 /* Handle the start of the SMTP session, then loop, accepting incoming
479 messages from the SMTP connection. The end will come at the QUIT command,
480 when smtp_setup_msg() returns 0. A break in the connection causes the
481 process to die (see accept.c).
483 NOTE: We do *not* call smtp_log_no_mail() if smtp_start_session() fails,
484 because a log line has already been written for all its failure exists
485 (usually "connection refused: <reason>") and writing another one is
486 unnecessary clutter. */
488 if (!smtp_start_session())
498 message_id[0] = 0; /* Clear out any previous message_id */
499 reset_point = store_get(0); /* Save current store high water point */
502 debug_printf("Process %d is ready for new message\n", (int)getpid());
504 /* Smtp_setup_msg() returns 0 on QUIT or if the call is from an
505 unacceptable host or if an ACL "drop" command was triggered, -1 on
506 connection lost, and +1 on validly reaching DATA. Receive_msg() almost
507 always returns TRUE when smtp_input is true; just retry if no message was
508 accepted (can happen for invalid message parameters). However, it can yield
509 FALSE if the connection was forcibly dropped by the DATA ACL. */
511 if ((rc = smtp_setup_msg()) > 0)
513 BOOL ok = receive_msg(FALSE);
514 search_tidyup(); /* Close cached databases */
515 if (!ok) /* Connection was dropped */
518 smtp_log_no_mail(); /* Log no mail if configured */
521 if (message_id[0] == 0) continue; /* No message was accepted */
527 smtp_log_no_mail(); /* Log no mail if configured */
528 _exit((rc == 0)? EXIT_SUCCESS : EXIT_FAILURE);
531 /* Show the recipients when debugging */
536 if (sender_address != NULL)
537 debug_printf("Sender: %s\n", sender_address);
538 if (recipients_list != NULL)
540 debug_printf("Recipients:\n");
541 for (i = 0; i < recipients_count; i++)
542 debug_printf(" %s\n", recipients_list[i].address);
546 /* A message has been accepted. Clean up any previous delivery processes
547 that have completed and are defunct, on systems where they don't go away
548 by themselves (see comments when setting SIG_IGN above). On such systems
549 (if any) these delivery processes hang around after termination until
550 the next message is received. */
552 #ifndef SIG_IGN_WORKS
553 while (waitpid(-1, NULL, WNOHANG) > 0);
556 /* Reclaim up the store used in accepting this message */
558 store_reset(reset_point);
560 /* If queue_only is set or if there are too many incoming connections in
561 existence, session_local_queue_only will be TRUE. If it is not, check
562 whether we have received too many messages in this session for immediate
565 if (!session_local_queue_only &&
566 smtp_accept_queue_per_connection > 0 &&
567 receive_messagecount > smtp_accept_queue_per_connection)
569 session_local_queue_only = TRUE;
570 queue_only_reason = 2;
573 /* Initialize local_queue_only from session_local_queue_only. If it is not
574 true, and queue_only_load is set, check that the load average is below it.
575 If local_queue_only is set by this means, we also set if for the session if
576 queue_only_load_latch is true (the default). This means that, once set,
577 local_queue_only remains set for any subsequent messages on the same SMTP
578 connection. This is a deliberate choice; even though the load average may
579 fall, it doesn't seem right to deliver later messages on the same call when
580 not delivering earlier ones. However, the are special circumstances such as
581 very long-lived connections from scanning appliances where this is not the
582 best strategy. In such cases, queue_only_load_latch should be set false. */
584 local_queue_only = session_local_queue_only;
585 if (!local_queue_only && queue_only_load >= 0)
587 local_queue_only = (load_average = OS_GETLOADAVG()) > queue_only_load;
588 if (local_queue_only)
590 queue_only_reason = 3;
591 if (queue_only_load_latch) session_local_queue_only = TRUE;
595 /* Log the queueing here, when it will get a message id attached, but
596 not if queue_only is set (case 0). */
598 if (local_queue_only) switch(queue_only_reason)
601 log_write(L_delay_delivery,
602 LOG_MAIN, "no immediate delivery: too many connections "
603 "(%d, max %d)", smtp_accept_count, smtp_accept_queue);
607 log_write(L_delay_delivery,
608 LOG_MAIN, "no immediate delivery: more than %d messages "
609 "received in one connection", smtp_accept_queue_per_connection);
613 log_write(L_delay_delivery,
614 LOG_MAIN, "no immediate delivery: load average %.2f",
615 (double)load_average/1000.0);
619 /* If a delivery attempt is required, spin off a new process to handle it.
620 If we are not root, we have to re-exec exim unless deliveries are being
621 done unprivileged. */
623 else if (!queue_only_policy && !deliver_freeze)
627 /* Before forking, ensure that the C output buffer is flushed. Otherwise
628 anything that it in it will get duplicated, leading to duplicate copies
629 of the pending output. */
633 if ((dpid = fork()) == 0)
635 (void)fclose(smtp_in);
636 (void)fclose(smtp_out);
638 /* Don't ever molest the parent's SSL connection, but do clean up
639 the data structures if necessary. */
642 tls_close(TRUE, FALSE);
645 /* Reset SIGHUP and SIGCHLD in the child in both cases. */
647 signal(SIGHUP, SIG_DFL);
648 signal(SIGCHLD, SIG_DFL);
650 if (geteuid() != root_uid && !deliver_drop_privilege)
652 signal(SIGALRM, SIG_DFL);
653 (void)child_exec_exim(CEE_EXEC_PANIC, FALSE, NULL, FALSE, 2, US"-Mc",
655 /* Control does not return here. */
658 /* No need to re-exec; SIGALRM remains set to the default handler */
660 (void)deliver_message(message_id, FALSE, FALSE);
667 DEBUG(D_any) debug_printf("forked delivery process %d\n", (int)dpid);
671 log_write(0, LOG_MAIN|LOG_PANIC, "daemon: delivery process fork "
672 "failed: %s", strerror(errno));
679 /* Carrying on in the parent daemon process... Can't do much if the fork
680 failed. Otherwise, keep count of the number of accepting processes and
681 remember the pid for ticking off when the child completes. */
685 never_error(US"daemon: accept process fork failed", US"Fork failed", errno);
690 for (i = 0; i < smtp_accept_max; ++i)
692 if (smtp_slots[i].pid <= 0)
694 smtp_slots[i].pid = pid;
695 if (smtp_accept_max_per_host != NULL)
696 smtp_slots[i].host_address = string_copy_malloc(sender_host_address);
701 DEBUG(D_any) debug_printf("%d SMTP accept process%s running\n",
702 smtp_accept_count, (smtp_accept_count == 1)? "" : "es");
705 /* Get here via goto in error cases */
709 /* Close the streams associated with the socket which will also close the
710 socket fds in this process. We can't do anything if fclose() fails, but
711 logging brings it to someone's attention. However, "connection reset by peer"
712 isn't really a problem, so skip that one. On Solaris, a dropped connection can
713 manifest itself as a broken pipe, so drop that one too. If the streams don't
714 exist, something went wrong while setting things up. Make sure the socket
715 descriptors are closed, in order to drop the connection. */
717 if (smtp_out != NULL)
719 if (fclose(smtp_out) != 0 && errno != ECONNRESET && errno != EPIPE)
720 log_write(0, LOG_MAIN|LOG_PANIC, "daemon: fclose(smtp_out) failed: %s",
724 else (void)close(accept_socket);
728 if (fclose(smtp_in) != 0 && errno != ECONNRESET && errno != EPIPE)
729 log_write(0, LOG_MAIN|LOG_PANIC, "daemon: fclose(smtp_in) failed: %s",
733 else (void)close(dup_accept_socket);
735 /* Release any store used in this process, including the store used for holding
736 the incoming host address and an expanded active_hostname. */
738 store_reset(reset_point);
739 sender_host_address = NULL;
745 /*************************************************
746 * Check wildcard listen special cases *
747 *************************************************/
749 /* This function is used when binding and listening on lists of addresses and
750 ports. It tests for special cases of wildcard listening, when IPv4 and IPv6
751 sockets may interact in different ways in different operating systems. It is
752 passed an error number, the list of listening addresses, and the current
753 address. Two checks are available: for a previous wildcard IPv6 address, or for
754 a following wildcard IPv4 address, in both cases on the same port.
756 In practice, pairs of wildcard addresses should be adjacent in the address list
757 because they are sorted that way below.
761 addresses the list of addresses
762 ipa the current IP address
763 back if TRUE, check for previous wildcard IPv6 address
764 if FALSE, check for a following wildcard IPv4 address
766 Returns: TRUE or FALSE
770 check_special_case(int eno, ip_address_item *addresses, ip_address_item *ipa,
773 ip_address_item *ipa2;
775 /* For the "back" case, if the failure was "address in use" for a wildcard IPv4
776 address, seek a previous IPv6 wildcard address on the same port. As it is
777 previous, it must have been successfully bound and be listening. Flag it as a
778 "6 including 4" listener. */
782 if (eno != EADDRINUSE || ipa->address[0] != 0) return FALSE;
783 for (ipa2 = addresses; ipa2 != ipa; ipa2 = ipa2->next)
785 if (ipa2->address[1] == 0 && ipa2->port == ipa->port)
787 ipa2->v6_include_v4 = TRUE;
793 /* For the "forward" case, if the current address is a wildcard IPv6 address,
794 we seek a following wildcard IPv4 address on the same port. */
798 if (ipa->address[0] != ':' || ipa->address[1] != 0) return FALSE;
799 for (ipa2 = ipa->next; ipa2 != NULL; ipa2 = ipa2->next)
800 if (ipa2->address[0] == 0 && ipa->port == ipa2->port) return TRUE;
809 /*************************************************
810 * Handle terminating subprocesses *
811 *************************************************/
813 /* Handle the termination of child processes. Theoretically, this need be done
814 only when sigchld_seen is TRUE, but rumour has it that some systems lose
815 SIGCHLD signals at busy times, so to be on the safe side, this function is
816 called each time round. It shouldn't be too expensive.
823 handle_ending_processes(void)
828 while ((pid = waitpid(-1, &status, WNOHANG)) > 0)
833 debug_printf("child %d ended: status=0x%x\n", (int)pid, status);
835 if (WIFEXITED(status))
836 debug_printf(" normal exit, %d\n", WEXITSTATUS(status));
837 else if (WIFSIGNALED(status))
838 debug_printf(" signal exit, signal %d%s\n", WTERMSIG(status),
839 WCOREDUMP(status) ? " (core dumped)" : "");
843 /* If it's a listening daemon for which we are keeping track of individual
844 subprocesses, deal with an accepting process that has terminated. */
846 if (smtp_slots != NULL)
848 for (i = 0; i < smtp_accept_max; i++)
850 if (smtp_slots[i].pid == pid)
852 if (smtp_slots[i].host_address != NULL)
853 store_free(smtp_slots[i].host_address);
854 smtp_slots[i] = empty_smtp_slot;
855 if (--smtp_accept_count < 0) smtp_accept_count = 0;
856 DEBUG(D_any) debug_printf("%d SMTP accept process%s now running\n",
857 smtp_accept_count, (smtp_accept_count == 1)? "" : "es");
861 if (i < smtp_accept_max) continue; /* Found an accepting process */
864 /* If it wasn't an accepting process, see if it was a queue-runner
865 process that we are tracking. */
867 if (queue_pid_slots != NULL)
869 for (i = 0; i < queue_run_max; i++)
871 if (queue_pid_slots[i] == pid)
873 queue_pid_slots[i] = 0;
874 if (--queue_run_count < 0) queue_run_count = 0;
875 DEBUG(D_any) debug_printf("%d queue-runner process%s now running\n",
876 queue_run_count, (queue_run_count == 1)? "" : "es");
886 /*************************************************
887 * Exim Daemon Mainline *
888 *************************************************/
890 /* The daemon can do two jobs, either of which is optional:
892 (1) Listens for incoming SMTP calls and spawns off a sub-process to handle
893 each one. This is requested by the -bd option, with -oX specifying the SMTP
894 port on which to listen (for testing).
896 (2) Spawns a queue-running process every so often. This is controlled by the
897 -q option with a an interval time. (If no time is given, a single queue run
898 is done from the main function, and control doesn't get here.)
900 Root privilege is required in order to attach to port 25. Some systems require
901 it when calling socket() rather than bind(). To cope with all cases, we run as
902 root for both socket() and bind(). Some systems also require root in order to
903 write to the pid file directory. This function must therefore be called as root
904 if it is to work properly in all circumstances. Once the socket is bound and
905 the pid file written, root privilege is given up if there is an exim uid.
907 There are no arguments to this function, and it never returns. */
913 int *listen_sockets = NULL;
914 int listen_socket_count = 0;
915 ip_address_item *addresses = NULL;
916 time_t last_connection_time = (time_t)0;
918 /* If any debugging options are set, turn on the D_pid bit so that all
919 debugging lines get the pid added. */
921 DEBUG(D_any|D_v) debug_selector |= D_pid;
927 listen_socket_count = 1;
928 listen_sockets = store_get(sizeof(int *));
930 if (dup2(0, 3) == -1)
932 log_write(0, LOG_MAIN|LOG_PANIC_DIE,
933 "failed to dup inetd socket safely away: %s", strerror(errno));
935 listen_sockets[0] = 3;
941 if (debug_file == stderr)
943 /* need a call to log_write before call to open debug_file, so that
944 log.c:file_path has been initialised. This is unfortunate. */
945 log_write(0, LOG_MAIN, "debugging Exim in inetd wait mode starting");
949 exim_nullstd(); /* re-open fd2 after we just closed it again */
950 debug_logging_activate(US"-wait", NULL);
953 DEBUG(D_any) debug_printf("running in inetd wait mode\n");
955 /* As per below, when creating sockets ourselves, we handle tcp_nodelay for
956 our own buffering; we assume though that inetd set the socket REUSEADDR. */
958 if (tcp_nodelay) setsockopt(3, IPPROTO_TCP, TCP_NODELAY,
959 (uschar *)(&on), sizeof(on));
963 if (inetd_wait_mode || daemon_listen)
965 /* If any option requiring a load average to be available during the
966 reception of a message is set, call os_getloadavg() while we are root
967 for those OS for which this is necessary the first time it is called (in
968 order to perform an "open" on the kernel memory file). */
970 #ifdef LOAD_AVG_NEEDS_ROOT
971 if (queue_only_load >= 0 || smtp_load_reserve >= 0 ||
972 (deliver_queue_load_max >= 0 && deliver_drop_privilege))
973 (void)os_getloadavg();
978 /* Do the preparation for setting up a listener on one or more interfaces, and
979 possible on various ports. This is controlled by the combination of
980 local_interfaces (which can set IP addresses and ports) and daemon_smtp_port
981 (which is a list of default ports to use for those items in local_interfaces
982 that do not specify a port). The -oX command line option can be used to
983 override one or both of these options.
985 If local_interfaces is not set, the default is to listen on all interfaces.
986 When it is set, it can include "all IPvx interfaces" as an item. This is useful
987 when different ports are in use.
989 It turns out that listening on all interfaces is messy in an IPv6 world,
990 because several different implementation approaches have been taken. This code
991 is now supposed to work with all of them. The point of difference is whether an
992 IPv6 socket that is listening on all interfaces will receive incoming IPv4
993 calls or not. We also have to cope with the case when IPv6 libraries exist, but
994 there is no IPv6 support in the kernel.
996 . On Solaris, an IPv6 socket will accept IPv4 calls, and give them as mapped
997 addresses. However, if an IPv4 socket is also listening on all interfaces,
998 calls are directed to the appropriate socket.
1000 . On (some versions of) Linux, an IPv6 socket will accept IPv4 calls, and
1001 give them as mapped addresses, but an attempt also to listen on an IPv4
1002 socket on all interfaces causes an error.
1004 . On OpenBSD, an IPv6 socket will not accept IPv4 calls. You have to set up
1005 two sockets if you want to accept both kinds of call.
1007 . FreeBSD is like OpenBSD, but it has the IPV6_V6ONLY socket option, which
1008 can be turned off, to make it behave like the versions of Linux described
1011 . I heard a report that the USAGI IPv6 stack for Linux has implemented
1014 So, what we do when IPv6 is supported is as follows:
1016 (1) After it is set up, the list of interfaces is scanned for wildcard
1017 addresses. If an IPv6 and an IPv4 wildcard are both found for the same
1018 port, the list is re-arranged so that they are together, with the IPv6
1021 (2) If the creation of a wildcard IPv6 socket fails, we just log the error and
1022 carry on if an IPv4 wildcard socket for the same port follows later in the
1023 list. This allows Exim to carry on in the case when the kernel has no IPv6
1026 (3) Having created an IPv6 wildcard socket, we try to set IPV6_V6ONLY if that
1027 option is defined. However, if setting fails, carry on regardless (but log
1030 (4) If binding or listening on an IPv6 wildcard socket fails, it is a serious
1033 (5) If binding or listening on an IPv4 wildcard socket fails with the error
1034 EADDRINUSE, and a previous interface was an IPv6 wildcard for the same
1035 port (which must have succeeded or we wouldn't have got this far), we
1036 assume we are in the situation where just a single socket is permitted,
1037 and ignore the error.
1041 The preparation code decodes options and sets up the relevant data. We do this
1042 first, so that we can return non-zero if there are any syntax errors, and also
1045 if (daemon_listen && !inetd_wait_mode)
1047 int *default_smtp_port;
1051 const uschar * list;
1052 uschar *local_iface_source = US"local_interfaces";
1053 ip_address_item *ipa;
1054 ip_address_item **pipa;
1056 /* If -oX was used, disable the writing of a pid file unless -oP was
1057 explicitly used to force it. Then scan the string given to -oX. Any items
1058 that contain neither a dot nor a colon are used to override daemon_smtp_port.
1059 Any other items are used to override local_interfaces. */
1061 if (override_local_interfaces != NULL)
1063 uschar *new_smtp_port = NULL;
1064 uschar *new_local_interfaces = NULL;
1070 if (override_pid_file_path == NULL) write_pid = FALSE;
1072 list = override_local_interfaces;
1074 while ((s = string_nextinlist(&list, &sep, big_buffer, big_buffer_size)))
1081 if (Ustrpbrk(s, ".:") == NULL)
1083 ptr = &new_smtp_port;
1084 sizeptr = &portsize;
1089 ptr = &new_local_interfaces;
1090 sizeptr = &ifacesize;
1098 *ptr = string_cat(*ptr, sizeptr, ptrptr, US"<", 1);
1101 *ptr = string_cat(*ptr, sizeptr, ptrptr, joinstr, 2);
1102 *ptr = string_cat(*ptr, sizeptr, ptrptr, s, Ustrlen(s));
1105 if (new_smtp_port != NULL)
1107 new_smtp_port[portptr] = 0;
1108 daemon_smtp_port = new_smtp_port;
1109 DEBUG(D_any) debug_printf("daemon_smtp_port overridden by -oX:\n %s\n",
1113 if (new_local_interfaces != NULL)
1115 new_local_interfaces[ifaceptr] = 0;
1116 local_interfaces = new_local_interfaces;
1117 local_iface_source = US"-oX data";
1118 DEBUG(D_any) debug_printf("local_interfaces overridden by -oX:\n %s\n",
1123 /* Create a list of default SMTP ports, to be used if local_interfaces
1124 contains entries without explict ports. First count the number of ports, then
1125 build a translated list in a vector. */
1127 list = daemon_smtp_port;
1129 while ((s = string_nextinlist(&list, &sep, big_buffer, big_buffer_size)))
1131 default_smtp_port = store_get((pct+1) * sizeof(int));
1132 list = daemon_smtp_port;
1135 (s = string_nextinlist(&list, &sep, big_buffer, big_buffer_size));
1141 default_smtp_port[pct] = Ustrtol(s, &end, 0);
1142 if (end != s + Ustrlen(s))
1143 log_write(0, LOG_PANIC_DIE|LOG_CONFIG, "invalid SMTP port: %s", s);
1147 struct servent *smtp_service = getservbyname(CS s, "tcp");
1149 log_write(0, LOG_PANIC_DIE|LOG_CONFIG, "TCP port \"%s\" not found", s);
1150 default_smtp_port[pct] = ntohs(smtp_service->s_port);
1153 default_smtp_port[pct] = 0;
1155 /* Check the list of TLS-on-connect ports and do name lookups if needed */
1157 list = tls_in.on_connect_ports;
1159 while ((s = string_nextinlist(&list, &sep, big_buffer, big_buffer_size)))
1162 list = tls_in.on_connect_ports;
1163 tls_in.on_connect_ports = NULL;
1165 while ((s = string_nextinlist(&list, &sep, big_buffer, big_buffer_size)))
1169 struct servent *smtp_service = getservbyname(CS s, "tcp");
1171 log_write(0, LOG_PANIC_DIE|LOG_CONFIG, "TCP port \"%s\" not found", s);
1172 s= string_sprintf("%d", (int)ntohs(smtp_service->s_port));
1174 tls_in.on_connect_ports = string_append_listele(tls_in.on_connect_ports,
1180 /* Create the list of local interfaces, possibly with ports included. This
1181 list may contain references to 0.0.0.0 and ::0 as wildcards. These special
1182 values are converted below. */
1184 addresses = host_build_ifacelist(local_interfaces, local_iface_source);
1186 /* In the list of IP addresses, convert 0.0.0.0 into an empty string, and ::0
1187 into the string ":". We use these to recognize wildcards in IPv4 and IPv6. In
1188 fact, many IP stacks recognize 0.0.0.0 and ::0 and handle them as wildcards
1189 anyway, but we need to know which are the wildcard addresses, and the shorter
1192 In the same scan, fill in missing port numbers from the default list. When
1193 there is more than one item in the list, extra items are created. */
1195 for (ipa = addresses; ipa != NULL; ipa = ipa->next)
1199 if (Ustrcmp(ipa->address, "0.0.0.0") == 0) ipa->address[0] = 0;
1200 else if (Ustrcmp(ipa->address, "::0") == 0)
1202 ipa->address[0] = ':';
1203 ipa->address[1] = 0;
1206 if (ipa->port > 0) continue;
1208 if (daemon_smtp_port[0] <= 0)
1209 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "no port specified for interface "
1210 "%s and daemon_smtp_port is unset; cannot start daemon",
1211 (ipa->address[0] == 0)? US"\"all IPv4\"" :
1212 (ipa->address[1] == 0)? US"\"all IPv6\"" : ipa->address);
1213 ipa->port = default_smtp_port[0];
1214 for (i = 1; default_smtp_port[i] > 0; i++)
1216 ip_address_item *new = store_get(sizeof(ip_address_item));
1217 memcpy(new->address, ipa->address, Ustrlen(ipa->address) + 1);
1218 new->port = default_smtp_port[i];
1219 new->next = ipa->next;
1225 /* Scan the list of addresses for wildcards. If we find an IPv4 and an IPv6
1226 wildcard for the same port, ensure that (a) they are together and (b) the
1227 IPv6 address comes first. This makes handling the messy features easier, and
1228 also simplifies the construction of the "daemon started" log line. */
1231 for (ipa = addresses; ipa != NULL; pipa = &(ipa->next), ipa = ipa->next)
1233 ip_address_item *ipa2;
1235 /* Handle an IPv4 wildcard */
1237 if (ipa->address[0] == 0)
1239 for (ipa2 = ipa; ipa2->next != NULL; ipa2 = ipa2->next)
1241 ip_address_item *ipa3 = ipa2->next;
1242 if (ipa3->address[0] == ':' &&
1243 ipa3->address[1] == 0 &&
1244 ipa3->port == ipa->port)
1246 ipa2->next = ipa3->next;
1254 /* Handle an IPv6 wildcard. */
1256 else if (ipa->address[0] == ':' && ipa->address[1] == 0)
1258 for (ipa2 = ipa; ipa2->next != NULL; ipa2 = ipa2->next)
1260 ip_address_item *ipa3 = ipa2->next;
1261 if (ipa3->address[0] == 0 && ipa3->port == ipa->port)
1263 ipa2->next = ipa3->next;
1264 ipa3->next = ipa->next;
1273 /* Get a vector to remember all the sockets in */
1275 for (ipa = addresses; ipa != NULL; ipa = ipa->next)
1276 listen_socket_count++;
1277 listen_sockets = store_get(sizeof(int *) * listen_socket_count);
1279 } /* daemon_listen but not inetd_wait_mode */
1284 /* Do a sanity check on the max connects value just to save us from getting
1285 a huge amount of store. */
1287 if (smtp_accept_max > 4095) smtp_accept_max = 4096;
1289 /* There's no point setting smtp_accept_queue unless it is less than the max
1290 connects limit. The configuration reader ensures that the max is set if the
1291 queue-only option is set. */
1293 if (smtp_accept_queue > smtp_accept_max) smtp_accept_queue = 0;
1295 /* Get somewhere to keep the list of SMTP accepting pids if we are keeping
1296 track of them for total number and queue/host limits. */
1298 if (smtp_accept_max > 0)
1301 smtp_slots = store_get(smtp_accept_max * sizeof(smtp_slot));
1302 for (i = 0; i < smtp_accept_max; i++) smtp_slots[i] = empty_smtp_slot;
1306 /* The variable background_daemon is always false when debugging, but
1307 can also be forced false in order to keep a non-debugging daemon in the
1308 foreground. If background_daemon is true, close all open file descriptors that
1309 we know about, but then re-open stdin, stdout, and stderr to /dev/null. Also
1310 do this for inetd_wait mode.
1312 This is protection against any called functions (in libraries, or in
1313 Perl, or whatever) that think they can write to stderr (or stdout). Before this
1314 was added, it was quite likely that an SMTP connection would use one of these
1315 file descriptors, in which case writing random stuff to it caused chaos.
1317 Then disconnect from the controlling terminal, Most modern Unixes seem to have
1318 setsid() for getting rid of the controlling terminal. For any OS that doesn't,
1319 setsid() can be #defined as a no-op, or as something else. */
1321 if (background_daemon || inetd_wait_mode)
1323 log_close_all(); /* Just in case anything was logged earlier */
1324 search_tidyup(); /* Just in case any were used in reading the config. */
1325 (void)close(0); /* Get rid of stdin/stdout/stderr */
1328 exim_nullstd(); /* Connect stdin/stdout/stderr to /dev/null */
1329 log_stderr = NULL; /* So no attempt to copy paniclog output */
1332 if (background_daemon)
1334 /* If the parent process of this one has pid == 1, we are re-initializing the
1335 daemon as the result of a SIGHUP. In this case, there is no need to do
1336 anything, because the controlling terminal has long gone. Otherwise, fork, in
1337 case current process is a process group leader (see 'man setsid' for an
1338 explanation) before calling setsid(). */
1343 if (pid < 0) log_write(0, LOG_MAIN|LOG_PANIC_DIE,
1344 "fork() failed when starting daemon: %s", strerror(errno));
1345 if (pid > 0) exit(EXIT_SUCCESS); /* in parent process, just exit */
1346 (void)setsid(); /* release controlling terminal */
1350 /* We are now in the disconnected, daemon process (unless debugging). Set up
1351 the listening sockets if required. */
1353 if (daemon_listen && !inetd_wait_mode)
1357 ip_address_item *ipa;
1359 /* For each IP address, create a socket, bind it to the appropriate port, and
1360 start listening. See comments above about IPv6 sockets that may or may not
1361 accept IPv4 calls when listening on all interfaces. We also have to cope with
1362 the case of a system with IPv6 libraries, but no IPv6 support in the kernel.
1363 listening, provided a wildcard IPv4 socket for the same port follows. */
1365 for (ipa = addresses, sk = 0; sk < listen_socket_count; ipa = ipa->next, sk++)
1368 ip_address_item *ipa2;
1371 if (Ustrchr(ipa->address, ':') != NULL)
1374 wildcard = ipa->address[1] == 0;
1379 wildcard = ipa->address[0] == 0;
1382 listen_sockets[sk] = ip_socket(SOCK_STREAM, af);
1383 if (listen_sockets[sk] < 0)
1385 if (check_special_case(0, addresses, ipa, FALSE))
1387 log_write(0, LOG_MAIN, "Failed to create IPv6 socket for wildcard "
1388 "listening (%s): will use IPv4", strerror(errno));
1391 log_write(0, LOG_PANIC_DIE, "IPv%c socket creation failed: %s",
1392 (af == AF_INET6)? '6' : '4', strerror(errno));
1395 /* If this is an IPv6 wildcard socket, set IPV6_V6ONLY if that option is
1396 available. Just log failure (can get protocol not available, just like
1397 socket creation can). */
1400 if (af == AF_INET6 && wildcard &&
1401 setsockopt(listen_sockets[sk], IPPROTO_IPV6, IPV6_V6ONLY, (char *)(&on),
1403 log_write(0, LOG_MAIN, "Setting IPV6_V6ONLY on daemon's IPv6 wildcard "
1404 "socket failed (%s): carrying on without it", strerror(errno));
1405 #endif /* IPV6_V6ONLY */
1407 /* Set SO_REUSEADDR so that the daemon can be restarted while a connection
1408 is being handled. Without this, a connection will prevent reuse of the
1409 smtp port for listening. */
1411 if (setsockopt(listen_sockets[sk], SOL_SOCKET, SO_REUSEADDR,
1412 (uschar *)(&on), sizeof(on)) < 0)
1413 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "setting SO_REUSEADDR on socket "
1414 "failed when starting daemon: %s", strerror(errno));
1416 /* Set TCP_NODELAY; Exim does its own buffering. There is a switch to
1417 disable this because it breaks some broken clients. */
1419 if (tcp_nodelay) setsockopt(listen_sockets[sk], IPPROTO_TCP, TCP_NODELAY,
1420 (uschar *)(&on), sizeof(on));
1422 /* Now bind the socket to the required port; if Exim is being restarted
1423 it may not always be possible to bind immediately, even with SO_REUSEADDR
1424 set, so try 10 times, waiting between each try. After 10 failures, we give
1425 up. In an IPv6 environment, if bind () fails with the error EADDRINUSE and
1426 we are doing wildcard IPv4 listening and there was a previous IPv6 wildcard
1427 address for the same port, ignore the error on the grounds that we must be
1428 in a system where the IPv6 socket accepts both kinds of call. This is
1429 necessary for (some release of) USAGI Linux; other IP stacks fail at the
1430 listen() stage instead. */
1435 if (ip_bind(listen_sockets[sk], af, ipa->address, ipa->port) >= 0) break;
1436 if (check_special_case(errno, addresses, ipa, TRUE))
1438 DEBUG(D_any) debug_printf("wildcard IPv4 bind() failed after IPv6 "
1439 "listen() success; EADDRINUSE ignored\n");
1440 (void)close(listen_sockets[sk]);
1443 msg = US strerror(errno);
1444 addr = wildcard? ((af == AF_INET6)? US"(any IPv6)" : US"(any IPv4)") :
1446 if (daemon_startup_retries <= 0)
1447 log_write(0, LOG_MAIN|LOG_PANIC_DIE,
1448 "socket bind() to port %d for address %s failed: %s: "
1449 "daemon abandoned", ipa->port, addr, msg);
1450 log_write(0, LOG_MAIN, "socket bind() to port %d for address %s "
1451 "failed: %s: waiting %s before trying again (%d more %s)",
1452 ipa->port, addr, msg, readconf_printtime(daemon_startup_sleep),
1453 daemon_startup_retries, (daemon_startup_retries > 1)? "tries" : "try");
1454 daemon_startup_retries--;
1455 sleep(daemon_startup_sleep);
1461 debug_printf("listening on all interfaces (IPv%c) port %d\n",
1462 (af == AF_INET6)? '6' : '4', ipa->port);
1464 debug_printf("listening on %s port %d\n", ipa->address, ipa->port);
1467 /* Start listening on the bound socket, establishing the maximum backlog of
1468 connections that is allowed. On success, continue to the next address. */
1470 if (listen(listen_sockets[sk], smtp_connect_backlog) >= 0) continue;
1472 /* Listening has failed. In an IPv6 environment, as for bind(), if listen()
1473 fails with the error EADDRINUSE and we are doing IPv4 wildcard listening
1474 and there was a previous successful IPv6 wildcard listen on the same port,
1475 we want to ignore the error on the grounds that we must be in a system
1476 where the IPv6 socket accepts both kinds of call. */
1478 if (!check_special_case(errno, addresses, ipa, TRUE))
1479 log_write(0, LOG_PANIC_DIE, "listen() failed on interface %s: %s",
1480 wildcard? ((af == AF_INET6)? US"(any IPv6)" : US"(any IPv4)") :
1484 DEBUG(D_any) debug_printf("wildcard IPv4 listen() failed after IPv6 "
1485 "listen() success; EADDRINUSE ignored\n");
1486 (void)close(listen_sockets[sk]);
1488 /* Come here if there has been a problem with the socket which we
1489 are going to ignore. We remove the address from the chain, and back up the
1493 sk--; /* Back up the count */
1494 listen_socket_count--; /* Reduce the total */
1495 if (ipa == addresses) addresses = ipa->next; else
1497 for (ipa2 = addresses; ipa2->next != ipa; ipa2 = ipa2->next);
1498 ipa2->next = ipa->next;
1501 } /* End of bind/listen loop for each address */
1502 } /* End of setup for listening */
1505 /* If we are not listening, we want to write a pid file only if -oP was
1506 explicitly given. */
1508 else if (override_pid_file_path == NULL) write_pid = FALSE;
1510 /* Write the pid to a known file for assistance in identification, if required.
1511 We do this before giving up root privilege, because on some systems it is
1512 necessary to be root in order to write into the pid file directory. There's
1513 nothing to stop multiple daemons running, as long as no more than one listens
1514 on a given TCP/IP port on the same interface(s). However, in these
1515 circumstances it gets far too complicated to mess with pid file names
1516 automatically. Consequently, Exim 4 writes a pid file only
1518 (a) When running in the test harness, or
1519 (b) When -bd is used and -oX is not used, or
1520 (c) When -oP is used to supply a path.
1522 The variable daemon_write_pid is used to control this. */
1524 if (running_in_test_harness || write_pid)
1528 if (override_pid_file_path != NULL)
1529 pid_file_path = override_pid_file_path;
1531 if (pid_file_path[0] == 0)
1532 pid_file_path = string_sprintf("%s/exim-daemon.pid", spool_directory);
1534 f = modefopen(pid_file_path, "wb", 0644);
1537 (void)fprintf(f, "%d\n", (int)getpid());
1539 DEBUG(D_any) debug_printf("pid written to %s\n", pid_file_path);
1544 debug_printf("%s\n", string_open_failed(errno, "pid file %s",
1549 /* Set up the handler for SIGHUP, which causes a restart of the daemon. */
1551 sighup_seen = FALSE;
1552 signal(SIGHUP, sighup_handler);
1554 /* Give up root privilege at this point (assuming that exim_uid and exim_gid
1555 are not root). The third argument controls the running of initgroups().
1556 Normally we do this, in order to set up the groups for the Exim user. However,
1557 if we are not root at this time - some odd installations run that way - we
1560 exim_setugid(exim_uid, exim_gid, geteuid()==root_uid, US"running as a daemon");
1562 /* Update the originator_xxx fields so that received messages as listed as
1563 coming from Exim, not whoever started the daemon. */
1565 originator_uid = exim_uid;
1566 originator_gid = exim_gid;
1567 originator_login = ((pw = getpwuid(exim_uid)) != NULL)?
1568 string_copy_malloc(US pw->pw_name) : US"exim";
1570 /* Get somewhere to keep the list of queue-runner pids if we are keeping track
1571 of them (and also if we are doing queue runs). */
1573 if (queue_interval > 0 && queue_run_max > 0)
1576 queue_pid_slots = store_get(queue_run_max * sizeof(pid_t));
1577 for (i = 0; i < queue_run_max; i++) queue_pid_slots[i] = 0;
1580 /* Set up the handler for termination of child processes. */
1582 sigchld_seen = FALSE;
1583 os_non_restarting_signal(SIGCHLD, main_sigchld_handler);
1585 /* If we are to run the queue periodically, pretend the alarm has just gone
1586 off. This will cause the first queue-runner to get kicked off straight away. */
1588 sigalrm_seen = (queue_interval > 0);
1590 /* Log the start up of a daemon - at least one of listening or queue running
1593 if (inetd_wait_mode)
1595 uschar *p = big_buffer;
1597 if (inetd_wait_timeout >= 0)
1598 sprintf(CS p, "terminating after %d seconds", inetd_wait_timeout);
1600 sprintf(CS p, "with no wait timeout");
1602 log_write(0, LOG_MAIN,
1603 "exim %s daemon started: pid=%d, launched with listening socket, %s",
1604 version_string, getpid(), big_buffer);
1605 set_process_info("daemon: pre-listening socket");
1607 /* set up the timeout logic */
1611 else if (daemon_listen)
1615 int smtps_ports = 0;
1616 ip_address_item *ipa;
1617 uschar *p = big_buffer;
1618 uschar *qinfo = (queue_interval > 0)?
1619 string_sprintf("-q%s", readconf_printtime(queue_interval))
1623 /* Build a list of listening addresses in big_buffer, but limit it to 10
1624 items. The style is for backwards compatibility.
1626 It is now possible to have some ports listening for SMTPS (the old,
1627 deprecated protocol that starts TLS without using STARTTLS), and others
1628 listening for standard SMTP. Keep their listings separate. */
1630 for (j = 0; j < 2; j++)
1632 for (i = 0, ipa = addresses; i < 10 && ipa != NULL; i++, ipa = ipa->next)
1634 /* First time round, look for SMTP ports; second time round, look for
1635 SMTPS ports. For the first one of each, insert leading text. */
1637 if (host_is_tls_on_connect_port(ipa->port) == (j > 0))
1641 if (smtp_ports++ == 0)
1643 memcpy(p, "SMTP on", 8);
1649 if (smtps_ports++ == 0)
1651 (void)sprintf(CS p, "%sSMTPS on",
1652 (smtp_ports == 0)? "":" and for ");
1653 while (*p != 0) p++;
1657 /* Now the information about the port (and sometimes interface) */
1659 if (ipa->address[0] == ':' && ipa->address[1] == 0)
1661 if (ipa->next != NULL && ipa->next->address[0] == 0 &&
1662 ipa->next->port == ipa->port)
1664 (void)sprintf(CS p, " port %d (IPv6 and IPv4)", ipa->port);
1667 else if (ipa->v6_include_v4)
1668 (void)sprintf(CS p, " port %d (IPv6 with IPv4)", ipa->port);
1670 (void)sprintf(CS p, " port %d (IPv6)", ipa->port);
1672 else if (ipa->address[0] == 0)
1673 (void)sprintf(CS p, " port %d (IPv4)", ipa->port);
1675 (void)sprintf(CS p, " [%s]:%d", ipa->address, ipa->port);
1676 while (*p != 0) p++;
1682 memcpy(p, " ...", 5);
1687 log_write(0, LOG_MAIN,
1688 "exim %s daemon started: pid=%d, %s, listening for %s",
1689 version_string, getpid(), qinfo, big_buffer);
1690 set_process_info("daemon: %s, listening for %s", qinfo, big_buffer);
1695 log_write(0, LOG_MAIN,
1696 "exim %s daemon started: pid=%d, -q%s, not listening for SMTP",
1697 version_string, getpid(), readconf_printtime(queue_interval));
1698 set_process_info("daemon: -q%s, not listening",
1699 readconf_printtime(queue_interval));
1702 /* Do any work it might be useful to amortize over our children
1703 (eg: compile regex) */
1708 #ifdef WITH_CONTENT_SCAN
1712 /* Close the log so it can be renamed and moved. In the few cases below where
1713 this long-running process writes to the log (always exceptional conditions), it
1714 closes the log afterwards, for the same reason. */
1718 DEBUG(D_any) debug_print_ids(US"daemon running with");
1720 /* Any messages accepted via this route are going to be SMTP. */
1724 /* Enter the never-ending loop... */
1729 struct sockaddr_in6 accepted;
1731 struct sockaddr_in accepted;
1737 /* This code is placed first in the loop, so that it gets obeyed at the
1738 start, before the first wait, for the queue-runner case, so that the first
1739 one can be started immediately.
1741 The other option is that we have an inetd wait timeout specified to -bw. */
1745 if (inetd_wait_timeout > 0)
1747 time_t resignal_interval = inetd_wait_timeout;
1749 if (last_connection_time == (time_t)0)
1752 debug_printf("inetd wait timeout expired, but still not seen first message, ignoring\n");
1756 time_t now = time(NULL);
1757 if (now == (time_t)-1)
1759 DEBUG(D_any) debug_printf("failed to get time: %s\n", strerror(errno));
1763 if ((now - last_connection_time) >= inetd_wait_timeout)
1766 debug_printf("inetd wait timeout %d expired, ending daemon\n",
1767 inetd_wait_timeout);
1768 log_write(0, LOG_MAIN, "exim %s daemon terminating, inetd wait timeout reached.\n",
1774 resignal_interval -= (now - last_connection_time);
1779 sigalrm_seen = FALSE;
1780 alarm(resignal_interval);
1785 DEBUG(D_any) debug_printf("SIGALRM received\n");
1787 /* Do a full queue run in a child process, if required, unless we already
1788 have enough queue runners on the go. If we are not running as root, a
1789 re-exec is required. */
1791 if (queue_interval > 0 &&
1792 (queue_run_max <= 0 || queue_run_count < queue_run_max))
1794 if ((pid = fork()) == 0)
1798 DEBUG(D_any) debug_printf("Starting queue-runner: pid %d\n",
1801 /* Disable debugging if it's required only for the daemon process. We
1802 leave the above message, because it ties up with the "child ended"
1803 debugging messages. */
1805 if (debug_daemon) debug_selector = 0;
1807 /* Close any open listening sockets in the child */
1809 for (sk = 0; sk < listen_socket_count; sk++)
1810 (void)close(listen_sockets[sk]);
1812 /* Reset SIGHUP and SIGCHLD in the child in both cases. */
1814 signal(SIGHUP, SIG_DFL);
1815 signal(SIGCHLD, SIG_DFL);
1817 /* Re-exec if privilege has been given up, unless deliver_drop_
1818 privilege is set. Reset SIGALRM before exec(). */
1820 if (geteuid() != root_uid && !deliver_drop_privilege)
1827 signal(SIGALRM, SIG_DFL);
1830 if (queue_2stage) *p++ = 'q';
1831 if (queue_run_first_delivery) *p++ = 'i';
1832 if (queue_run_force) *p++ = 'f';
1833 if (deliver_force_thaw) *p++ = 'f';
1834 if (queue_run_local) *p++ = 'l';
1838 /* If -R or -S were on the original command line, ensure they get
1841 if (deliver_selectstring != NULL)
1843 extra[extracount++] = deliver_selectstring_regex? US"-Rr" : US"-R";
1844 extra[extracount++] = deliver_selectstring;
1847 if (deliver_selectstring_sender != NULL)
1849 extra[extracount++] = deliver_selectstring_sender_regex?
1851 extra[extracount++] = deliver_selectstring_sender;
1854 /* Overlay this process with a new execution. */
1856 (void)child_exec_exim(CEE_EXEC_PANIC, FALSE, NULL, TRUE, extracount,
1857 extra[0], extra[1], extra[2], extra[3], extra[4]);
1859 /* Control never returns here. */
1862 /* No need to re-exec; SIGALRM remains set to the default handler */
1864 queue_run(NULL, NULL, FALSE);
1865 _exit(EXIT_SUCCESS);
1870 log_write(0, LOG_MAIN|LOG_PANIC, "daemon: fork of queue-runner "
1871 "process failed: %s", strerror(errno));
1877 for (i = 0; i < queue_run_max; ++i)
1879 if (queue_pid_slots[i] <= 0)
1881 queue_pid_slots[i] = pid;
1886 DEBUG(D_any) debug_printf("%d queue-runner process%s running\n",
1887 queue_run_count, (queue_run_count == 1)? "" : "es");
1891 /* Reset the alarm clock */
1893 sigalrm_seen = FALSE;
1894 alarm(queue_interval);
1897 } /* sigalrm_seen */
1900 /* Sleep till a connection happens if listening, and handle the connection if
1901 that is why we woke up. The FreeBSD operating system requires the use of
1902 select() before accept() because the latter function is not interrupted by
1903 a signal, and we want to wake up for SIGCHLD and SIGALRM signals. Some other
1904 OS do notice signals in accept() but it does no harm to have the select()
1905 in for all of them - and it won't then be a lurking problem for ports to
1906 new OS. In fact, the later addition of listening on specific interfaces only
1907 requires this way of working anyway. */
1911 int sk, lcount, select_errno;
1913 BOOL select_failed = FALSE;
1914 fd_set select_listen;
1916 FD_ZERO(&select_listen);
1917 for (sk = 0; sk < listen_socket_count; sk++)
1919 FD_SET(listen_sockets[sk], &select_listen);
1920 if (listen_sockets[sk] > max_socket) max_socket = listen_sockets[sk];
1923 DEBUG(D_any) debug_printf("Listening...\n");
1925 /* In rare cases we may have had a SIGCHLD signal in the time between
1926 setting the handler (below) and getting back here. If so, pretend that the
1927 select() was interrupted so that we reap the child. This might still leave
1928 a small window when a SIGCHLD could get lost. However, since we use SIGCHLD
1929 only to do the reaping more quickly, it shouldn't result in anything other
1930 than a delay until something else causes a wake-up. */
1939 lcount = select(max_socket + 1, (SELECT_ARG2_TYPE *)&select_listen,
1945 select_failed = TRUE;
1949 /* Clean up any subprocesses that may have terminated. We need to do this
1950 here so that smtp_accept_max_per_host works when a connection to that host
1951 has completed, and we are about to accept a new one. When this code was
1952 later in the sequence, a new connection could be rejected, even though an
1953 old one had just finished. Preserve the errno from any select() failure for
1954 the use of the common select/accept error processing below. */
1956 select_errno = errno;
1957 handle_ending_processes();
1958 errno = select_errno;
1960 /* Loop for all the sockets that are currently ready to go. If select
1961 actually failed, we have set the count to 1 and select_failed=TRUE, so as
1962 to use the common error code for select/accept below. */
1964 while (lcount-- > 0)
1966 int accept_socket = -1;
1969 for (sk = 0; sk < listen_socket_count; sk++)
1971 if (FD_ISSET(listen_sockets[sk], &select_listen))
1973 len = sizeof(accepted);
1974 accept_socket = accept(listen_sockets[sk],
1975 (struct sockaddr *)&accepted, &len);
1976 FD_CLR(listen_sockets[sk], &select_listen);
1982 /* If select or accept has failed and this was not caused by an
1983 interruption, log the incident and try again. With asymmetric TCP/IP
1984 routing errors such as "No route to network" have been seen here. Also
1985 "connection reset by peer" has been seen. These cannot be classed as
1986 disastrous errors, but they could fill up a lot of log. The code in smail
1987 crashes the daemon after 10 successive failures of accept, on the grounds
1988 that some OS fail continuously. Exim originally followed suit, but this
1989 appears to have caused problems. Now it just keeps going, but instead of
1990 logging each error, it batches them up when they are continuous. */
1992 if (accept_socket < 0 && errno != EINTR)
1994 if (accept_retry_count == 0)
1996 accept_retry_errno = errno;
1997 accept_retry_select_failed = select_failed;
2001 if (errno != accept_retry_errno ||
2002 select_failed != accept_retry_select_failed ||
2003 accept_retry_count >= 50)
2005 log_write(0, LOG_MAIN | ((accept_retry_count >= 50)? LOG_PANIC : 0),
2006 "%d %s() failure%s: %s",
2008 accept_retry_select_failed? "select" : "accept",
2009 (accept_retry_count == 1)? "" : "s",
2010 strerror(accept_retry_errno));
2012 accept_retry_count = 0;
2013 accept_retry_errno = errno;
2014 accept_retry_select_failed = select_failed;
2017 accept_retry_count++;
2022 if (accept_retry_count > 0)
2024 log_write(0, LOG_MAIN, "%d %s() failure%s: %s",
2026 accept_retry_select_failed? "select" : "accept",
2027 (accept_retry_count == 1)? "" : "s",
2028 strerror(accept_retry_errno));
2030 accept_retry_count = 0;
2034 /* If select/accept succeeded, deal with the connection. */
2036 if (accept_socket >= 0)
2038 if (inetd_wait_timeout)
2039 last_connection_time = time(NULL);
2040 handle_smtp_call(listen_sockets, listen_socket_count, accept_socket,
2041 (struct sockaddr *)&accepted);
2046 /* If not listening, then just sleep for the queue interval. If we woke
2047 up early the last time for some other signal, it won't matter because
2048 the alarm signal will wake at the right time. This code originally used
2049 sleep() but it turns out that on the FreeBSD system, sleep() is not inter-
2050 rupted by signals, so it wasn't waking up for SIGALRM or SIGCHLD. Luckily
2051 select() can be used as an interruptible sleep() on all versions of Unix. */
2056 tv.tv_sec = queue_interval;
2058 select(0, NULL, NULL, NULL, &tv);
2059 handle_ending_processes();
2062 /* Re-enable the SIGCHLD handler if it has been run. It can't do it
2063 for itself, because it isn't doing the waiting itself. */
2067 sigchld_seen = FALSE;
2068 os_non_restarting_signal(SIGCHLD, main_sigchld_handler);
2071 /* Handle being woken by SIGHUP. We know at this point that the result
2072 of accept() has been dealt with, so we can re-exec exim safely, first
2073 closing the listening sockets so that they can be reused. Cancel any pending
2074 alarm in case it is just about to go off, and set SIGHUP to be ignored so
2075 that another HUP in quick succession doesn't clobber the new daemon before it
2076 gets going. All log files get closed by the close-on-exec flag; however, if
2077 the exec fails, we need to close the logs. */
2082 log_write(0, LOG_MAIN, "pid %d: SIGHUP received: re-exec daemon",
2084 for (sk = 0; sk < listen_socket_count; sk++)
2085 (void)close(listen_sockets[sk]);
2087 signal(SIGHUP, SIG_IGN);
2088 sighup_argv[0] = exim_path;
2090 execv(CS exim_path, (char *const *)sighup_argv);
2091 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "pid %d: exec of %s failed: %s",
2092 getpid(), exim_path, strerror(errno));
2096 } /* End of main loop */
2098 /* Control never reaches here */
2103 /* End of exim_daemon.c */