Close logs after daemon-process exceptional write. Bug 728
[exim.git] / src / src / daemon.c
CommitLineData
059ec3d9
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1/*************************************************
2* Exim - an Internet mail transport agent *
3*************************************************/
4
3386088d 5/* Copyright (c) University of Cambridge 1995 - 2015 */
059ec3d9
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6/* See the file NOTICE for conditions of use and distribution. */
7
8/* Functions concerned with running Exim as a daemon */
9
10
11#include "exim.h"
12
13
14/* Structure for holding data for each SMTP connection */
15
16typedef struct smtp_slot {
17 pid_t pid; /* pid of the spawned reception process */
18 uschar *host_address; /* address of the client host */
19} smtp_slot;
20
21/* An empty slot for initializing (Standard C does not allow constructor
22expressions in assigments except as initializers in declarations). */
23
24static smtp_slot empty_smtp_slot = { 0, NULL };
25
26
27
28/*************************************************
29* Local static variables *
30*************************************************/
31
cd59ab18
PP
32static SIGNAL_BOOL sigchld_seen;
33static SIGNAL_BOOL sighup_seen;
059ec3d9
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34
35static int accept_retry_count = 0;
36static int accept_retry_errno;
37static BOOL accept_retry_select_failed;
38
39static int queue_run_count = 0;
bb6e88ff
PH
40static pid_t *queue_pid_slots = NULL;
41static smtp_slot *smtp_slots = NULL;
059ec3d9
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42
43static BOOL write_pid = TRUE;
44
45
46
47/*************************************************
48* SIGHUP Handler *
49*************************************************/
50
51/* All this handler does is to set a flag and re-enable the signal.
52
53Argument: the signal number
54Returns: nothing
55*/
56
57static void
58sighup_handler(int sig)
59{
60sig = sig; /* Keep picky compilers happy */
61sighup_seen = TRUE;
62signal(SIGHUP, sighup_handler);
63}
64
65
66
67/*************************************************
68* SIGCHLD handler for main daemon process *
69*************************************************/
70
71/* Don't re-enable the handler here, since we aren't doing the
72waiting here. If the signal is re-enabled, there will just be an
73infinite sequence of calls to this handler. The SIGCHLD signal is
74used just as a means of waking up the daemon so that it notices
75terminated subprocesses as soon as possible.
76
77Argument: the signal number
78Returns: nothing
79*/
80
81static void
82main_sigchld_handler(int sig)
83{
84sig = sig; /* Keep picky compilers happy */
7d468ab8 85os_non_restarting_signal(SIGCHLD, SIG_DFL);
059ec3d9 86sigchld_seen = TRUE;
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PH
87}
88
89
90
91
92/*************************************************
93* Unexpected errors in SMTP calls *
94*************************************************/
95
96/* This function just saves a bit of repetitious coding.
97
98Arguments:
99 log_msg Text of message to be logged
100 smtp_msg Text of SMTP error message
101 was_errno The failing errno
102
103Returns: nothing
104*/
105
106static void
107never_error(uschar *log_msg, uschar *smtp_msg, int was_errno)
108{
109uschar *emsg = (was_errno <= 0)? US"" :
110 string_sprintf(": %s", strerror(was_errno));
111log_write(0, LOG_MAIN|LOG_PANIC, "%s%s", log_msg, emsg);
112if (smtp_out != NULL) smtp_printf("421 %s\r\n", smtp_msg);
113}
114
115
116
117
118/*************************************************
119* Handle a connected SMTP call *
120*************************************************/
121
122/* This function is called when an SMTP connection has been accepted.
123If there are too many, give an error message and close down. Otherwise
124spin off a sub-process to handle the call. The list of listening sockets
125is required so that they can be closed in the sub-process. Take care not to
126leak store in this process - reset the stacking pool at the end.
127
128Arguments:
129 listen_sockets sockets which are listening for incoming calls
130 listen_socket_count count of listening sockets
131 accept_socket socket of the current accepted call
132 accepted socket information about the current call
133
134Returns: nothing
135*/
136
137static void
138handle_smtp_call(int *listen_sockets, int listen_socket_count,
139 int accept_socket, struct sockaddr *accepted)
140{
141pid_t pid;
142union sockaddr_46 interface_sockaddr;
36a3b041 143EXIM_SOCKLEN_T ifsize = sizeof(interface_sockaddr);
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144int dup_accept_socket = -1;
145int max_for_this_host = 0;
146int wfsize = 0;
147int wfptr = 0;
6c6d6e48 148int save_log_selector = *log_selector;
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149uschar *whofrom = NULL;
150
151void *reset_point = store_get(0);
152
153/* Make the address available in ASCII representation, and also fish out
154the remote port. */
155
156sender_host_address = host_ntoa(-1, accepted, NULL, &sender_host_port);
157DEBUG(D_any) debug_printf("Connection request from %s port %d\n",
158 sender_host_address, sender_host_port);
159
160/* Set up the output stream, check the socket has duplicated, and set up the
161input stream. These operations fail only the exceptional circumstances. Note
162that never_error() won't use smtp_out if it is NULL. */
163
164smtp_out = fdopen(accept_socket, "wb");
165if (smtp_out == NULL)
166 {
167 never_error(US"daemon: fdopen() for smtp_out failed", US"", errno);
168 goto ERROR_RETURN;
169 }
170
171dup_accept_socket = dup(accept_socket);
172if (dup_accept_socket < 0)
173 {
174 never_error(US"daemon: couldn't dup socket descriptor",
175 US"Connection setup failed", errno);
176 goto ERROR_RETURN;
177 }
178
179smtp_in = fdopen(dup_accept_socket, "rb");
180if (smtp_in == NULL)
181 {
182 never_error(US"daemon: fdopen() for smtp_in failed",
183 US"Connection setup failed", errno);
184 goto ERROR_RETURN;
185 }
186
520de300
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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. */
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189
190if (getsockname(accept_socket, (struct sockaddr *)(&interface_sockaddr),
191 &ifsize) < 0)
192 {
520de300
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193 log_write(0, LOG_MAIN | ((errno == ECONNRESET)? 0 : LOG_PANIC),
194 "getsockname() failed: %s", strerror(errno));
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195 smtp_printf("421 Local problem: getsockname() failed; please try again later\r\n");
196 goto ERROR_RETURN;
197 }
198
199interface_address = host_ntoa(-1, &interface_sockaddr, NULL, &interface_port);
200DEBUG(D_interface) debug_printf("interface address=%s port=%d\n",
201 interface_address, interface_port);
202
203/* Build a string identifying the remote host and, if requested, the port and
204the local interface data. This is for logging; at the end of this function the
205memory is reclaimed. */
206
207whofrom = string_append(whofrom, &wfsize, &wfptr, 3, "[", sender_host_address, "]");
208
6c6d6e48 209if (LOGGING(incoming_port))
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210 whofrom = string_append(whofrom, &wfsize, &wfptr, 2, ":", string_sprintf("%d",
211 sender_host_port));
212
6c6d6e48 213if (LOGGING(incoming_interface))
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214 whofrom = string_append(whofrom, &wfsize, &wfptr, 4, " I=[",
215 interface_address, "]:", string_sprintf("%d", interface_port));
216
217whofrom[wfptr] = 0; /* Terminate the newly-built string */
218
219/* Check maximum number of connections. We do not check for reserved
220connections or unacceptable hosts here. That is done in the subprocess because
221it might take some time. */
222
223if (smtp_accept_max > 0 && smtp_accept_count >= smtp_accept_max)
224 {
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",
231 whofrom);
232 goto ERROR_RETURN;
233 }
234
235/* If a load limit above which only reserved hosts are acceptable is defined,
236get the load average here, and if there are in fact no reserved hosts, do
237the test right away (saves a fork). If there are hosts, do the check in the
238subprocess because it might take time. */
239
240if (smtp_load_reserve >= 0)
241 {
8669f003 242 load_average = OS_GETLOADAVG();
059ec3d9
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243 if (smtp_reserve_hosts == NULL && load_average > smtp_load_reserve)
244 {
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);
251 goto ERROR_RETURN;
252 }
253 }
254
255/* Check that one specific host (strictly, IP address) is not hogging
256resources. This is done here to prevent a denial of service attack by someone
257forcing you to fork lots of times before denying service. The value of
258smtp_accept_max_per_host is a string which is expanded. This makes it possible
259to provide host-specific limits according to $sender_host address, but because
260this is in the daemon mainline, only fast expansions (such as inline address
261checks) should be used. The documentation is full of warnings. */
262
263if (smtp_accept_max_per_host != NULL)
264 {
265 uschar *expanded = expand_string(smtp_accept_max_per_host);
266 if (expanded == NULL)
267 {
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);
271 }
272 /* For speed, interpret a decimal number inline here */
273 else
274 {
275 uschar *s = expanded;
276 while (isdigit(*s))
277 max_for_this_host = max_for_this_host * 10 + *s++ - '0';
278 if (*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);
281 }
282 }
283
284/* If we have fewer connections than max_for_this_host, we can skip the tedious
285per host_address checks. Note that at this stage smtp_accept_count contains the
286count of *other* connections, not including this one. */
287
288if ((max_for_this_host > 0) &&
289 (smtp_accept_count >= max_for_this_host))
290 {
291 int i;
292 int host_accept_count = 0;
293 int other_host_count = 0; /* keep a count of non matches to optimise */
294
295 for (i = 0; i < smtp_accept_max; ++i)
296 {
297 if (smtp_slots[i].host_address != NULL)
298 {
299 if (Ustrcmp(sender_host_address, smtp_slots[i].host_address) == 0)
300 host_accept_count++;
301 else
302 other_host_count++;
303
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. */
307
308 if ((host_accept_count >= max_for_this_host) ||
309 ((smtp_accept_count - other_host_count) < max_for_this_host))
310 break;
311 }
312 }
313
314 if (host_accept_count >= max_for_this_host)
315 {
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);
324 goto ERROR_RETURN;
325 }
326 }
327
328/* OK, the connection count checks have been passed. Before we can fork the
329accepting process, we must first log the connection if requested. This logging
330used to happen in the subprocess, but doing that means that the value of
331smtp_accept_count can be out of step by the time it is logged. So we have to do
332the logging here and accept the performance cost. Note that smtp_accept_count
333hasn't yet been incremented to take account of this connection.
334
335In order to minimize the cost (because this is going to happen for every
336connection), do a preliminary selector test here. This saves ploughing through
337the generalized logging code each time when the selector is false. If the
338selector is set, check whether the host is on the list for logging. If not,
339arrange to unset the selector in the subprocess. */
340
6c6d6e48 341if (LOGGING(smtp_connection))
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PH
342 {
343 uschar *list = hosts_connection_nolog;
344 if (list != NULL && verify_check_host(&list) == OK)
6c6d6e48 345 save_log_selector &= ~L_smtp_connection;
059ec3d9
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346 else
347 log_write(L_smtp_connection, LOG_MAIN, "SMTP connection from %s "
348 "(TCP/IP connection count = %d)", whofrom, smtp_accept_count + 1);
349 }
350
351/* Now we can fork the accepting process; do a lookup tidy, just in case any
352expansion above did a lookup. */
353
354search_tidyup();
355pid = fork();
356
357/* Handle the child process */
358
359if (pid == 0)
360 {
361 int i;
362 int queue_only_reason = 0;
363 int old_pool = store_pool;
8e669ac1 364 int save_debug_selector = debug_selector;
059ec3d9 365 BOOL local_queue_only;
8669f003 366 BOOL session_local_queue_only;
059ec3d9
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367 #ifdef SA_NOCLDWAIT
368 struct sigaction act;
369 #endif
370
b01dd148
PH
371 smtp_accept_count++; /* So that it includes this process */
372
059ec3d9
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373 /* May have been modified for the subprocess */
374
6c6d6e48 375 *log_selector = save_log_selector;
059ec3d9
PH
376
377 /* Get the local interface address into permanent store */
378
379 store_pool = POOL_PERM;
380 interface_address = string_copy(interface_address);
381 store_pool = old_pool;
382
383 /* Check for a tls-on-connect port */
384
817d9f57 385 if (host_is_tls_on_connect_port(interface_port)) tls_in.on_connect = TRUE;
059ec3d9
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386
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.) */
390
391 smtp_active_hostname = primary_hostname;
392 if (raw_active_hostname != NULL)
393 {
394 uschar *nah = expand_string(raw_active_hostname);
395 if (nah == NULL)
396 {
397 if (!expand_string_forcedfail)
398 {
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");
404 mac_smtp_fflush();
405 search_tidyup();
406 _exit(EXIT_FAILURE);
407 }
408 }
409 else if (nah[0] != 0) smtp_active_hostname = nah;
410 }
411
412 /* Initialize the queueing flags */
413
414 queue_check_only();
8669f003 415 session_local_queue_only = queue_only;
059ec3d9
PH
416
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. */
423
f1e894f3 424 for (i = 0; i < listen_socket_count; i++) (void)close(listen_sockets[i]);
059ec3d9 425
fa32850b
DW
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);
432
059ec3d9
PH
433 #ifdef SA_NOCLDWAIT
434 act.sa_handler = SIG_IGN;
435 sigemptyset(&(act.sa_mask));
436 act.sa_flags = SA_NOCLDWAIT;
437 sigaction(SIGCHLD, &act, NULL);
438 #else
439 signal(SIGCHLD, SIG_IGN);
440 #endif
441
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
8e669ac1
PH
445 in case there is no HELO/EHLO.
446
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
3d235903 449 incoming connection is output. */
8e669ac1 450
3d235903 451 if (debug_daemon) debug_selector = 0;
059ec3d9
PH
452 verify_get_ident(IDENT_PORT);
453 host_build_sender_fullhost();
8e669ac1 454 debug_selector = save_debug_selector;
059ec3d9
PH
455
456 DEBUG(D_any)
457 debug_printf("Process %d is handling incoming connection from %s\n",
458 (int)getpid(), sender_fullhost);
459
3d235903
PH
460 /* Now disable debugging permanently if it's required only for the daemon
461 process. */
462
463 if (debug_daemon) debug_selector = 0;
464
059ec3d9 465 /* If there are too many child processes for immediate delivery,
8669f003 466 set the session_local_queue_only flag, which is initialized from the
059ec3d9 467 configured value and may therefore already be TRUE. Leave logging
8669f003
PH
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. */
059ec3d9 471
b01dd148 472 if (smtp_accept_queue > 0 && smtp_accept_count > smtp_accept_queue)
059ec3d9 473 {
8669f003 474 session_local_queue_only = TRUE;
059ec3d9
PH
475 queue_only_reason = 1;
476 }
477
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
24796b8d
PH
481 process to die (see accept.c).
482
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. */
059ec3d9
PH
487
488 if (!smtp_start_session())
489 {
490 mac_smtp_fflush();
491 search_tidyup();
492 _exit(EXIT_SUCCESS);
493 }
494
495 for (;;)
496 {
497 int rc;
498 message_id[0] = 0; /* Clear out any previous message_id */
499 reset_point = store_get(0); /* Save current store high water point */
500
501 DEBUG(D_any)
502 debug_printf("Process %d is ready for new message\n", (int)getpid());
503
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. */
510
511 if ((rc = smtp_setup_msg()) > 0)
512 {
513 BOOL ok = receive_msg(FALSE);
514 search_tidyup(); /* Close cached databases */
515 if (!ok) /* Connection was dropped */
516 {
517 mac_smtp_fflush();
b4ed4da0 518 smtp_log_no_mail(); /* Log no mail if configured */
059ec3d9
PH
519 _exit(EXIT_SUCCESS);
520 }
521 if (message_id[0] == 0) continue; /* No message was accepted */
522 }
523 else
524 {
525 mac_smtp_fflush();
526 search_tidyup();
b4ed4da0 527 smtp_log_no_mail(); /* Log no mail if configured */
059ec3d9
PH
528 _exit((rc == 0)? EXIT_SUCCESS : EXIT_FAILURE);
529 }
530
531 /* Show the recipients when debugging */
532
533 DEBUG(D_receive)
534 {
535 int i;
536 if (sender_address != NULL)
537 debug_printf("Sender: %s\n", sender_address);
538 if (recipients_list != NULL)
539 {
540 debug_printf("Recipients:\n");
541 for (i = 0; i < recipients_count; i++)
542 debug_printf(" %s\n", recipients_list[i].address);
543 }
544 }
545
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. */
551
552 #ifndef SIG_IGN_WORKS
553 while (waitpid(-1, NULL, WNOHANG) > 0);
554 #endif
555
556 /* Reclaim up the store used in accepting this message */
557
558 store_reset(reset_point);
559
560 /* If queue_only is set or if there are too many incoming connections in
8669f003
PH
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
563 delivery. */
564
565 if (!session_local_queue_only &&
566 smtp_accept_queue_per_connection > 0 &&
567 receive_messagecount > smtp_accept_queue_per_connection)
059ec3d9 568 {
8669f003
PH
569 session_local_queue_only = TRUE;
570 queue_only_reason = 2;
571 }
572
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. */
583
584 local_queue_only = session_local_queue_only;
585 if (!local_queue_only && queue_only_load >= 0)
586 {
587 local_queue_only = (load_average = OS_GETLOADAVG()) > queue_only_load;
588 if (local_queue_only)
059ec3d9 589 {
8669f003
PH
590 queue_only_reason = 3;
591 if (queue_only_load_latch) session_local_queue_only = TRUE;
059ec3d9
PH
592 }
593 }
594
595 /* Log the queueing here, when it will get a message id attached, but
596 not if queue_only is set (case 0). */
597
598 if (local_queue_only) switch(queue_only_reason)
599 {
600 case 1:
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);
604 break;
605
606 case 2:
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);
610 break;
611
612 case 3:
613 log_write(L_delay_delivery,
614 LOG_MAIN, "no immediate delivery: load average %.2f",
615 (double)load_average/1000.0);
616 break;
617 }
618
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. */
622
623 else if (!queue_only_policy && !deliver_freeze)
624 {
625 pid_t dpid;
626
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. */
630
631 mac_smtp_fflush();
632
633 if ((dpid = fork()) == 0)
634 {
f1e894f3
PH
635 (void)fclose(smtp_in);
636 (void)fclose(smtp_out);
059ec3d9
PH
637
638 /* Don't ever molest the parent's SSL connection, but do clean up
639 the data structures if necessary. */
640
641 #ifdef SUPPORT_TLS
a400eccf 642 tls_close(TRUE, FALSE);
059ec3d9
PH
643 #endif
644
645 /* Reset SIGHUP and SIGCHLD in the child in both cases. */
646
647 signal(SIGHUP, SIG_DFL);
648 signal(SIGCHLD, SIG_DFL);
649
650 if (geteuid() != root_uid && !deliver_drop_privilege)
651 {
652 signal(SIGALRM, SIG_DFL);
653 (void)child_exec_exim(CEE_EXEC_PANIC, FALSE, NULL, FALSE, 2, US"-Mc",
654 message_id);
655 /* Control does not return here. */
656 }
657
658 /* No need to re-exec; SIGALRM remains set to the default handler */
659
660 (void)deliver_message(message_id, FALSE, FALSE);
661 search_tidyup();
662 _exit(EXIT_SUCCESS);
663 }
664
665 if (dpid > 0)
666 {
667 DEBUG(D_any) debug_printf("forked delivery process %d\n", (int)dpid);
668 }
669 else
670 {
671 log_write(0, LOG_MAIN|LOG_PANIC, "daemon: delivery process fork "
672 "failed: %s", strerror(errno));
673 }
674 }
675 }
676 }
677
678
679/* Carrying on in the parent daemon process... Can't do much if the fork
680failed. Otherwise, keep count of the number of accepting processes and
681remember the pid for ticking off when the child completes. */
682
683if (pid < 0)
684 {
685 never_error(US"daemon: accept process fork failed", US"Fork failed", errno);
686 }
687else
688 {
689 int i;
690 for (i = 0; i < smtp_accept_max; ++i)
691 {
692 if (smtp_slots[i].pid <= 0)
693 {
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);
697 smtp_accept_count++;
698 break;
699 }
700 }
701 DEBUG(D_any) debug_printf("%d SMTP accept process%s running\n",
702 smtp_accept_count, (smtp_accept_count == 1)? "" : "es");
703 }
704
705/* Get here via goto in error cases */
706
707ERROR_RETURN:
708
709/* Close the streams associated with the socket which will also close the
710socket fds in this process. We can't do anything if fclose() fails, but
711logging brings it to someone's attention. However, "connection reset by peer"
1f872c80
PH
712isn't really a problem, so skip that one. On Solaris, a dropped connection can
713manifest itself as a broken pipe, so drop that one too. If the streams don't
714exist, something went wrong while setting things up. Make sure the socket
715descriptors are closed, in order to drop the connection. */
059ec3d9
PH
716
717if (smtp_out != NULL)
718 {
1f872c80 719 if (fclose(smtp_out) != 0 && errno != ECONNRESET && errno != EPIPE)
059ec3d9
PH
720 log_write(0, LOG_MAIN|LOG_PANIC, "daemon: fclose(smtp_out) failed: %s",
721 strerror(errno));
722 smtp_out = NULL;
723 }
f1e894f3 724else (void)close(accept_socket);
059ec3d9
PH
725
726if (smtp_in != NULL)
727 {
1f872c80 728 if (fclose(smtp_in) != 0 && errno != ECONNRESET && errno != EPIPE)
059ec3d9
PH
729 log_write(0, LOG_MAIN|LOG_PANIC, "daemon: fclose(smtp_in) failed: %s",
730 strerror(errno));
731 smtp_in = NULL;
732 }
f1e894f3 733else (void)close(dup_accept_socket);
059ec3d9
PH
734
735/* Release any store used in this process, including the store used for holding
736the incoming host address and an expanded active_hostname. */
737
c8899c20 738log_close_all();
059ec3d9
PH
739store_reset(reset_point);
740sender_host_address = NULL;
741}
742
743
744
745
746/*************************************************
747* Check wildcard listen special cases *
748*************************************************/
749
750/* This function is used when binding and listening on lists of addresses and
751ports. It tests for special cases of wildcard listening, when IPv4 and IPv6
752sockets may interact in different ways in different operating systems. It is
753passed an error number, the list of listening addresses, and the current
754address. Two checks are available: for a previous wildcard IPv6 address, or for
755a following wildcard IPv4 address, in both cases on the same port.
756
757In practice, pairs of wildcard addresses should be adjacent in the address list
758because they are sorted that way below.
759
760Arguments:
761 eno the error number
762 addresses the list of addresses
763 ipa the current IP address
764 back if TRUE, check for previous wildcard IPv6 address
765 if FALSE, check for a following wildcard IPv4 address
766
767Returns: TRUE or FALSE
768*/
769
770static BOOL
771check_special_case(int eno, ip_address_item *addresses, ip_address_item *ipa,
772 BOOL back)
773{
774ip_address_item *ipa2;
775
776/* For the "back" case, if the failure was "address in use" for a wildcard IPv4
777address, seek a previous IPv6 wildcard address on the same port. As it is
778previous, it must have been successfully bound and be listening. Flag it as a
779"6 including 4" listener. */
780
781if (back)
782 {
783 if (eno != EADDRINUSE || ipa->address[0] != 0) return FALSE;
784 for (ipa2 = addresses; ipa2 != ipa; ipa2 = ipa2->next)
785 {
786 if (ipa2->address[1] == 0 && ipa2->port == ipa->port)
787 {
788 ipa2->v6_include_v4 = TRUE;
789 return TRUE;
790 }
791 }
792 }
793
794/* For the "forward" case, if the current address is a wildcard IPv6 address,
795we seek a following wildcard IPv4 address on the same port. */
796
797else
798 {
799 if (ipa->address[0] != ':' || ipa->address[1] != 0) return FALSE;
800 for (ipa2 = ipa->next; ipa2 != NULL; ipa2 = ipa2->next)
801 if (ipa2->address[0] == 0 && ipa->port == ipa2->port) return TRUE;
802 }
803
804return FALSE;
805}
806
807
808
809
bb6e88ff
PH
810/*************************************************
811* Handle terminating subprocesses *
812*************************************************/
813
814/* Handle the termination of child processes. Theoretically, this need be done
815only when sigchld_seen is TRUE, but rumour has it that some systems lose
816SIGCHLD signals at busy times, so to be on the safe side, this function is
817called each time round. It shouldn't be too expensive.
818
819Arguments: none
820Returns: nothing
821*/
822
823static void
824handle_ending_processes(void)
825{
826int status;
827pid_t pid;
828
829while ((pid = waitpid(-1, &status, WNOHANG)) > 0)
830 {
831 int i;
7be682ca
PP
832 DEBUG(D_any)
833 {
834 debug_printf("child %d ended: status=0x%x\n", (int)pid, status);
835#ifdef WCOREDUMP
836 if (WIFEXITED(status))
837 debug_printf(" normal exit, %d\n", WEXITSTATUS(status));
838 else if (WIFSIGNALED(status))
839 debug_printf(" signal exit, signal %d%s\n", WTERMSIG(status),
840 WCOREDUMP(status) ? " (core dumped)" : "");
841#endif
842 }
bb6e88ff 843
8e669ac1 844 /* If it's a listening daemon for which we are keeping track of individual
bb6e88ff
PH
845 subprocesses, deal with an accepting process that has terminated. */
846
847 if (smtp_slots != NULL)
848 {
849 for (i = 0; i < smtp_accept_max; i++)
850 {
851 if (smtp_slots[i].pid == pid)
852 {
853 if (smtp_slots[i].host_address != NULL)
854 store_free(smtp_slots[i].host_address);
855 smtp_slots[i] = empty_smtp_slot;
856 if (--smtp_accept_count < 0) smtp_accept_count = 0;
857 DEBUG(D_any) debug_printf("%d SMTP accept process%s now running\n",
858 smtp_accept_count, (smtp_accept_count == 1)? "" : "es");
859 break;
860 }
861 }
862 if (i < smtp_accept_max) continue; /* Found an accepting process */
863 }
864
865 /* If it wasn't an accepting process, see if it was a queue-runner
866 process that we are tracking. */
867
868 if (queue_pid_slots != NULL)
869 {
870 for (i = 0; i < queue_run_max; i++)
871 {
872 if (queue_pid_slots[i] == pid)
873 {
874 queue_pid_slots[i] = 0;
875 if (--queue_run_count < 0) queue_run_count = 0;
876 DEBUG(D_any) debug_printf("%d queue-runner process%s now running\n",
877 queue_run_count, (queue_run_count == 1)? "" : "es");
878 break;
879 }
880 }
881 }
882 }
883}
884
059ec3d9
PH
885
886
887/*************************************************
888* Exim Daemon Mainline *
889*************************************************/
890
891/* The daemon can do two jobs, either of which is optional:
892
893(1) Listens for incoming SMTP calls and spawns off a sub-process to handle
894each one. This is requested by the -bd option, with -oX specifying the SMTP
895port on which to listen (for testing).
896
897(2) Spawns a queue-running process every so often. This is controlled by the
898-q option with a an interval time. (If no time is given, a single queue run
899is done from the main function, and control doesn't get here.)
900
901Root privilege is required in order to attach to port 25. Some systems require
902it when calling socket() rather than bind(). To cope with all cases, we run as
903root for both socket() and bind(). Some systems also require root in order to
904write to the pid file directory. This function must therefore be called as root
905if it is to work properly in all circumstances. Once the socket is bound and
906the pid file written, root privilege is given up if there is an exim uid.
907
908There are no arguments to this function, and it never returns. */
909
910void
911daemon_go(void)
912{
ebeaf996 913struct passwd *pw;
059ec3d9
PH
914int *listen_sockets = NULL;
915int listen_socket_count = 0;
916ip_address_item *addresses = NULL;
9ee44efb 917time_t last_connection_time = (time_t)0;
059ec3d9
PH
918
919/* If any debugging options are set, turn on the D_pid bit so that all
920debugging lines get the pid added. */
921
922DEBUG(D_any|D_v) debug_selector |= D_pid;
923
9ee44efb
PP
924if (inetd_wait_mode)
925 {
926 int on = 1;
927
928 listen_socket_count = 1;
929 listen_sockets = store_get(sizeof(int *));
930 (void) close(3);
931 if (dup2(0, 3) == -1)
932 {
933 log_write(0, LOG_MAIN|LOG_PANIC_DIE,
934 "failed to dup inetd socket safely away: %s", strerror(errno));
935 }
936 listen_sockets[0] = 3;
937 (void) close(0);
938 (void) close(1);
939 (void) close(2);
940 exim_nullstd();
941
942 if (debug_file == stderr)
943 {
944 /* need a call to log_write before call to open debug_file, so that
945 log.c:file_path has been initialised. This is unfortunate. */
946 log_write(0, LOG_MAIN, "debugging Exim in inetd wait mode starting");
947
948 fclose(debug_file);
949 debug_file = NULL;
950 exim_nullstd(); /* re-open fd2 after we just closed it again */
951 debug_logging_activate(US"-wait", NULL);
952 }
953
954 DEBUG(D_any) debug_printf("running in inetd wait mode\n");
955
956 /* As per below, when creating sockets ourselves, we handle tcp_nodelay for
957 our own buffering; we assume though that inetd set the socket REUSEADDR. */
958
959 if (tcp_nodelay) setsockopt(3, IPPROTO_TCP, TCP_NODELAY,
960 (uschar *)(&on), sizeof(on));
961 }
962
963
964if (inetd_wait_mode || daemon_listen)
965 {
966 /* If any option requiring a load average to be available during the
967 reception of a message is set, call os_getloadavg() while we are root
968 for those OS for which this is necessary the first time it is called (in
969 order to perform an "open" on the kernel memory file). */
970
971 #ifdef LOAD_AVG_NEEDS_ROOT
972 if (queue_only_load >= 0 || smtp_load_reserve >= 0 ||
973 (deliver_queue_load_max >= 0 && deliver_drop_privilege))
974 (void)os_getloadavg();
975 #endif
976 }
977
059ec3d9
PH
978
979/* Do the preparation for setting up a listener on one or more interfaces, and
980possible on various ports. This is controlled by the combination of
981local_interfaces (which can set IP addresses and ports) and daemon_smtp_port
982(which is a list of default ports to use for those items in local_interfaces
983that do not specify a port). The -oX command line option can be used to
984override one or both of these options.
985
986If local_interfaces is not set, the default is to listen on all interfaces.
987When it is set, it can include "all IPvx interfaces" as an item. This is useful
988when different ports are in use.
989
990It turns out that listening on all interfaces is messy in an IPv6 world,
991because several different implementation approaches have been taken. This code
992is now supposed to work with all of them. The point of difference is whether an
993IPv6 socket that is listening on all interfaces will receive incoming IPv4
994calls or not. We also have to cope with the case when IPv6 libraries exist, but
995there is no IPv6 support in the kernel.
996
997. On Solaris, an IPv6 socket will accept IPv4 calls, and give them as mapped
998 addresses. However, if an IPv4 socket is also listening on all interfaces,
999 calls are directed to the appropriate socket.
1000
1001. On (some versions of) Linux, an IPv6 socket will accept IPv4 calls, and
1002 give them as mapped addresses, but an attempt also to listen on an IPv4
1003 socket on all interfaces causes an error.
1004
1005. On OpenBSD, an IPv6 socket will not accept IPv4 calls. You have to set up
1006 two sockets if you want to accept both kinds of call.
1007
1008. FreeBSD is like OpenBSD, but it has the IPV6_V6ONLY socket option, which
1009 can be turned off, to make it behave like the versions of Linux described
1010 above.
1011
1012. I heard a report that the USAGI IPv6 stack for Linux has implemented
1013 IPV6_V6ONLY.
1014
1015So, what we do when IPv6 is supported is as follows:
1016
1017 (1) After it is set up, the list of interfaces is scanned for wildcard
1018 addresses. If an IPv6 and an IPv4 wildcard are both found for the same
1019 port, the list is re-arranged so that they are together, with the IPv6
1020 wildcard first.
1021
1022 (2) If the creation of a wildcard IPv6 socket fails, we just log the error and
1023 carry on if an IPv4 wildcard socket for the same port follows later in the
1024 list. This allows Exim to carry on in the case when the kernel has no IPv6
1025 support.
1026
1027 (3) Having created an IPv6 wildcard socket, we try to set IPV6_V6ONLY if that
1028 option is defined. However, if setting fails, carry on regardless (but log
1029 the incident).
1030
1031 (4) If binding or listening on an IPv6 wildcard socket fails, it is a serious
1032 error.
1033
1034 (5) If binding or listening on an IPv4 wildcard socket fails with the error
1035 EADDRINUSE, and a previous interface was an IPv6 wildcard for the same
1036 port (which must have succeeded or we wouldn't have got this far), we
1037 assume we are in the situation where just a single socket is permitted,
1038 and ignore the error.
1039
1040Phew!
1041
1042The preparation code decodes options and sets up the relevant data. We do this
1043first, so that we can return non-zero if there are any syntax errors, and also
1044write to stderr. */
1045
602e0254 1046if (daemon_listen && !inetd_wait_mode)
059ec3d9
PH
1047 {
1048 int *default_smtp_port;
1049 int sep;
1050 int pct = 0;
1051 uschar *s;
55414b25 1052 const uschar * list;
059ec3d9
PH
1053 uschar *local_iface_source = US"local_interfaces";
1054 ip_address_item *ipa;
1055 ip_address_item **pipa;
1056
059ec3d9
PH
1057 /* If -oX was used, disable the writing of a pid file unless -oP was
1058 explicitly used to force it. Then scan the string given to -oX. Any items
1059 that contain neither a dot nor a colon are used to override daemon_smtp_port.
1060 Any other items are used to override local_interfaces. */
1061
1062 if (override_local_interfaces != NULL)
1063 {
1064 uschar *new_smtp_port = NULL;
1065 uschar *new_local_interfaces = NULL;
1066 int portsize = 0;
1067 int portptr = 0;
1068 int ifacesize = 0;
1069 int ifaceptr = 0;
1070
1071 if (override_pid_file_path == NULL) write_pid = FALSE;
1072
1073 list = override_local_interfaces;
1074 sep = 0;
55414b25 1075 while ((s = string_nextinlist(&list, &sep, big_buffer, big_buffer_size)))
059ec3d9
PH
1076 {
1077 uschar joinstr[4];
1078 uschar **ptr;
1079 int *sizeptr;
1080 int *ptrptr;
1081
1082 if (Ustrpbrk(s, ".:") == NULL)
1083 {
1084 ptr = &new_smtp_port;
1085 sizeptr = &portsize;
1086 ptrptr = &portptr;
1087 }
1088 else
1089 {
1090 ptr = &new_local_interfaces;
1091 sizeptr = &ifacesize;
1092 ptrptr = &ifaceptr;
1093 }
1094
1095 if (*ptr == NULL)
1096 {
1097 joinstr[0] = sep;
1098 joinstr[1] = ' ';
1099 *ptr = string_cat(*ptr, sizeptr, ptrptr, US"<", 1);
1100 }
1101
1102 *ptr = string_cat(*ptr, sizeptr, ptrptr, joinstr, 2);
1103 *ptr = string_cat(*ptr, sizeptr, ptrptr, s, Ustrlen(s));
1104 }
1105
1106 if (new_smtp_port != NULL)
1107 {
1108 new_smtp_port[portptr] = 0;
1109 daemon_smtp_port = new_smtp_port;
1110 DEBUG(D_any) debug_printf("daemon_smtp_port overridden by -oX:\n %s\n",
1111 daemon_smtp_port);
1112 }
1113
1114 if (new_local_interfaces != NULL)
1115 {
1116 new_local_interfaces[ifaceptr] = 0;
1117 local_interfaces = new_local_interfaces;
1118 local_iface_source = US"-oX data";
1119 DEBUG(D_any) debug_printf("local_interfaces overridden by -oX:\n %s\n",
1120 local_interfaces);
1121 }
1122 }
1123
1124 /* Create a list of default SMTP ports, to be used if local_interfaces
1125 contains entries without explict ports. First count the number of ports, then
1126 build a translated list in a vector. */
1127
1128 list = daemon_smtp_port;
1129 sep = 0;
55414b25 1130 while ((s = string_nextinlist(&list, &sep, big_buffer, big_buffer_size)))
059ec3d9
PH
1131 pct++;
1132 default_smtp_port = store_get((pct+1) * sizeof(int));
1133 list = daemon_smtp_port;
1134 sep = 0;
1135 for (pct = 0;
55414b25 1136 (s = string_nextinlist(&list, &sep, big_buffer, big_buffer_size));
059ec3d9
PH
1137 pct++)
1138 {
1139 if (isdigit(*s))
1140 {
1141 uschar *end;
1142 default_smtp_port[pct] = Ustrtol(s, &end, 0);
1143 if (end != s + Ustrlen(s))
1144 log_write(0, LOG_PANIC_DIE|LOG_CONFIG, "invalid SMTP port: %s", s);
1145 }
1146 else
1147 {
1148 struct servent *smtp_service = getservbyname(CS s, "tcp");
071c51f7 1149 if (!smtp_service)
059ec3d9
PH
1150 log_write(0, LOG_PANIC_DIE|LOG_CONFIG, "TCP port \"%s\" not found", s);
1151 default_smtp_port[pct] = ntohs(smtp_service->s_port);
1152 }
1153 }
1154 default_smtp_port[pct] = 0;
1155
071c51f7
JH
1156 /* Check the list of TLS-on-connect ports and do name lookups if needed */
1157
1158 list = tls_in.on_connect_ports;
1159 sep = 0;
1160 while ((s = string_nextinlist(&list, &sep, big_buffer, big_buffer_size)))
1161 if (!isdigit(*s))
1162 {
1163 list = tls_in.on_connect_ports;
1164 tls_in.on_connect_ports = NULL;
1165 sep = 0;
1166 while ((s = string_nextinlist(&list, &sep, big_buffer, big_buffer_size)))
1167 {
1168 if (!isdigit(*s))
1169 {
1170 struct servent *smtp_service = getservbyname(CS s, "tcp");
1171 if (!smtp_service)
1172 log_write(0, LOG_PANIC_DIE|LOG_CONFIG, "TCP port \"%s\" not found", s);
1173 s= string_sprintf("%d", (int)ntohs(smtp_service->s_port));
1174 }
1175 tls_in.on_connect_ports = string_append_listele(tls_in.on_connect_ports,
1176 ':', s);
1177 }
1178 break;
1179 }
1180
059ec3d9
PH
1181 /* Create the list of local interfaces, possibly with ports included. This
1182 list may contain references to 0.0.0.0 and ::0 as wildcards. These special
1183 values are converted below. */
1184
1185 addresses = host_build_ifacelist(local_interfaces, local_iface_source);
1186
1187 /* In the list of IP addresses, convert 0.0.0.0 into an empty string, and ::0
1188 into the string ":". We use these to recognize wildcards in IPv4 and IPv6. In
1189 fact, many IP stacks recognize 0.0.0.0 and ::0 and handle them as wildcards
1190 anyway, but we need to know which are the wildcard addresses, and the shorter
1191 strings are neater.
1192
1193 In the same scan, fill in missing port numbers from the default list. When
1194 there is more than one item in the list, extra items are created. */
1195
1196 for (ipa = addresses; ipa != NULL; ipa = ipa->next)
1197 {
1198 int i;
1199
1200 if (Ustrcmp(ipa->address, "0.0.0.0") == 0) ipa->address[0] = 0;
1201 else if (Ustrcmp(ipa->address, "::0") == 0)
1202 {
1203 ipa->address[0] = ':';
1204 ipa->address[1] = 0;
1205 }
1206
1207 if (ipa->port > 0) continue;
1208
1209 if (daemon_smtp_port[0] <= 0)
1210 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "no port specified for interface "
1211 "%s and daemon_smtp_port is unset; cannot start daemon",
1212 (ipa->address[0] == 0)? US"\"all IPv4\"" :
1213 (ipa->address[1] == 0)? US"\"all IPv6\"" : ipa->address);
1214 ipa->port = default_smtp_port[0];
1215 for (i = 1; default_smtp_port[i] > 0; i++)
1216 {
1217 ip_address_item *new = store_get(sizeof(ip_address_item));
1218 memcpy(new->address, ipa->address, Ustrlen(ipa->address) + 1);
1219 new->port = default_smtp_port[i];
1220 new->next = ipa->next;
1221 ipa->next = new;
1222 ipa = new;
1223 }
1224 }
1225
1226 /* Scan the list of addresses for wildcards. If we find an IPv4 and an IPv6
1227 wildcard for the same port, ensure that (a) they are together and (b) the
1228 IPv6 address comes first. This makes handling the messy features easier, and
1229 also simplifies the construction of the "daemon started" log line. */
1230
1231 pipa = &addresses;
1232 for (ipa = addresses; ipa != NULL; pipa = &(ipa->next), ipa = ipa->next)
1233 {
1234 ip_address_item *ipa2;
1235
1236 /* Handle an IPv4 wildcard */
1237
1238 if (ipa->address[0] == 0)
1239 {
1240 for (ipa2 = ipa; ipa2->next != NULL; ipa2 = ipa2->next)
1241 {
1242 ip_address_item *ipa3 = ipa2->next;
1243 if (ipa3->address[0] == ':' &&
1244 ipa3->address[1] == 0 &&
1245 ipa3->port == ipa->port)
1246 {
1247 ipa2->next = ipa3->next;
1248 ipa3->next = ipa;
1249 *pipa = ipa3;
1250 break;
1251 }
1252 }
1253 }
1254
1255 /* Handle an IPv6 wildcard. */
1256
1257 else if (ipa->address[0] == ':' && ipa->address[1] == 0)
1258 {
1259 for (ipa2 = ipa; ipa2->next != NULL; ipa2 = ipa2->next)
1260 {
1261 ip_address_item *ipa3 = ipa2->next;
1262 if (ipa3->address[0] == 0 && ipa3->port == ipa->port)
1263 {
1264 ipa2->next = ipa3->next;
1265 ipa3->next = ipa->next;
1266 ipa->next = ipa3;
1267 ipa = ipa3;
1268 break;
1269 }
1270 }
1271 }
1272 }
1273
1274 /* Get a vector to remember all the sockets in */
1275
1276 for (ipa = addresses; ipa != NULL; ipa = ipa->next)
1277 listen_socket_count++;
1278 listen_sockets = store_get(sizeof(int *) * listen_socket_count);
1279
9ee44efb
PP
1280 } /* daemon_listen but not inetd_wait_mode */
1281
1282if (daemon_listen)
1283 {
1284
059ec3d9
PH
1285 /* Do a sanity check on the max connects value just to save us from getting
1286 a huge amount of store. */
1287
1288 if (smtp_accept_max > 4095) smtp_accept_max = 4096;
1289
1290 /* There's no point setting smtp_accept_queue unless it is less than the max
1291 connects limit. The configuration reader ensures that the max is set if the
1292 queue-only option is set. */
1293
1294 if (smtp_accept_queue > smtp_accept_max) smtp_accept_queue = 0;
1295
1296 /* Get somewhere to keep the list of SMTP accepting pids if we are keeping
1297 track of them for total number and queue/host limits. */
1298
1299 if (smtp_accept_max > 0)
1300 {
1301 int i;
1302 smtp_slots = store_get(smtp_accept_max * sizeof(smtp_slot));
1303 for (i = 0; i < smtp_accept_max; i++) smtp_slots[i] = empty_smtp_slot;
1304 }
1305 }
1306
76a2d7ba
PH
1307/* The variable background_daemon is always false when debugging, but
1308can also be forced false in order to keep a non-debugging daemon in the
1309foreground. If background_daemon is true, close all open file descriptors that
9ee44efb
PP
1310we know about, but then re-open stdin, stdout, and stderr to /dev/null. Also
1311do this for inetd_wait mode.
76a2d7ba
PH
1312
1313This is protection against any called functions (in libraries, or in
1314Perl, or whatever) that think they can write to stderr (or stdout). Before this
1315was added, it was quite likely that an SMTP connection would use one of these
1316file descriptors, in which case writing random stuff to it caused chaos.
1317
1318Then disconnect from the controlling terminal, Most modern Unixes seem to have
1319setsid() for getting rid of the controlling terminal. For any OS that doesn't,
1320setsid() can be #defined as a no-op, or as something else. */
059ec3d9 1321
9ee44efb 1322if (background_daemon || inetd_wait_mode)
059ec3d9 1323 {
76a2d7ba
PH
1324 log_close_all(); /* Just in case anything was logged earlier */
1325 search_tidyup(); /* Just in case any were used in reading the config. */
f1e894f3
PH
1326 (void)close(0); /* Get rid of stdin/stdout/stderr */
1327 (void)close(1);
1328 (void)close(2);
8e669ac1 1329 exim_nullstd(); /* Connect stdin/stdout/stderr to /dev/null */
059ec3d9 1330 log_stderr = NULL; /* So no attempt to copy paniclog output */
9ee44efb 1331 }
059ec3d9 1332
9ee44efb
PP
1333if (background_daemon)
1334 {
059ec3d9 1335 /* If the parent process of this one has pid == 1, we are re-initializing the
8e669ac1 1336 daemon as the result of a SIGHUP. In this case, there is no need to do
76a2d7ba
PH
1337 anything, because the controlling terminal has long gone. Otherwise, fork, in
1338 case current process is a process group leader (see 'man setsid' for an
1339 explanation) before calling setsid(). */
059ec3d9
PH
1340
1341 if (getppid() != 1)
1342 {
1343 pid_t pid = fork();
1344 if (pid < 0) log_write(0, LOG_MAIN|LOG_PANIC_DIE,
1345 "fork() failed when starting daemon: %s", strerror(errno));
1346 if (pid > 0) exit(EXIT_SUCCESS); /* in parent process, just exit */
1347 (void)setsid(); /* release controlling terminal */
1348 }
1349 }
1350
1351/* We are now in the disconnected, daemon process (unless debugging). Set up
1352the listening sockets if required. */
1353
9ee44efb 1354if (daemon_listen && !inetd_wait_mode)
059ec3d9
PH
1355 {
1356 int sk;
1357 int on = 1;
1358 ip_address_item *ipa;
1359
1360 /* For each IP address, create a socket, bind it to the appropriate port, and
1361 start listening. See comments above about IPv6 sockets that may or may not
1362 accept IPv4 calls when listening on all interfaces. We also have to cope with
1363 the case of a system with IPv6 libraries, but no IPv6 support in the kernel.
1364 listening, provided a wildcard IPv4 socket for the same port follows. */
1365
1366 for (ipa = addresses, sk = 0; sk < listen_socket_count; ipa = ipa->next, sk++)
1367 {
1368 BOOL wildcard;
1369 ip_address_item *ipa2;
059ec3d9
PH
1370 int af;
1371
1372 if (Ustrchr(ipa->address, ':') != NULL)
1373 {
1374 af = AF_INET6;
1375 wildcard = ipa->address[1] == 0;
1376 }
1377 else
1378 {
1379 af = AF_INET;
1380 wildcard = ipa->address[0] == 0;
1381 }
1382
1383 listen_sockets[sk] = ip_socket(SOCK_STREAM, af);
1384 if (listen_sockets[sk] < 0)
1385 {
1386 if (check_special_case(0, addresses, ipa, FALSE))
1387 {
1388 log_write(0, LOG_MAIN, "Failed to create IPv6 socket for wildcard "
1389 "listening (%s): will use IPv4", strerror(errno));
1390 goto SKIP_SOCKET;
1391 }
1392 log_write(0, LOG_PANIC_DIE, "IPv%c socket creation failed: %s",
1393 (af == AF_INET6)? '6' : '4', strerror(errno));
1394 }
1395
1396 /* If this is an IPv6 wildcard socket, set IPV6_V6ONLY if that option is
1397 available. Just log failure (can get protocol not available, just like
1398 socket creation can). */
1399
1400 #ifdef IPV6_V6ONLY
1401 if (af == AF_INET6 && wildcard &&
1402 setsockopt(listen_sockets[sk], IPPROTO_IPV6, IPV6_V6ONLY, (char *)(&on),
1403 sizeof(on)) < 0)
1404 log_write(0, LOG_MAIN, "Setting IPV6_V6ONLY on daemon's IPv6 wildcard "
1405 "socket failed (%s): carrying on without it", strerror(errno));
1406 #endif /* IPV6_V6ONLY */
1407
1408 /* Set SO_REUSEADDR so that the daemon can be restarted while a connection
1409 is being handled. Without this, a connection will prevent reuse of the
1410 smtp port for listening. */
1411
1412 if (setsockopt(listen_sockets[sk], SOL_SOCKET, SO_REUSEADDR,
1413 (uschar *)(&on), sizeof(on)) < 0)
1414 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "setting SO_REUSEADDR on socket "
1415 "failed when starting daemon: %s", strerror(errno));
1416
1417 /* Set TCP_NODELAY; Exim does its own buffering. There is a switch to
1418 disable this because it breaks some broken clients. */
1419
1420 if (tcp_nodelay) setsockopt(listen_sockets[sk], IPPROTO_TCP, TCP_NODELAY,
1421 (uschar *)(&on), sizeof(on));
1422
1423 /* Now bind the socket to the required port; if Exim is being restarted
1424 it may not always be possible to bind immediately, even with SO_REUSEADDR
1425 set, so try 10 times, waiting between each try. After 10 failures, we give
1426 up. In an IPv6 environment, if bind () fails with the error EADDRINUSE and
1427 we are doing wildcard IPv4 listening and there was a previous IPv6 wildcard
1428 address for the same port, ignore the error on the grounds that we must be
1429 in a system where the IPv6 socket accepts both kinds of call. This is
1430 necessary for (some release of) USAGI Linux; other IP stacks fail at the
1431 listen() stage instead. */
1432
1433 for(;;)
1434 {
1435 uschar *msg, *addr;
1436 if (ip_bind(listen_sockets[sk], af, ipa->address, ipa->port) >= 0) break;
1437 if (check_special_case(errno, addresses, ipa, TRUE))
1438 {
1439 DEBUG(D_any) debug_printf("wildcard IPv4 bind() failed after IPv6 "
1440 "listen() success; EADDRINUSE ignored\n");
f1e894f3 1441 (void)close(listen_sockets[sk]);
059ec3d9
PH
1442 goto SKIP_SOCKET;
1443 }
1444 msg = US strerror(errno);
1445 addr = wildcard? ((af == AF_INET6)? US"(any IPv6)" : US"(any IPv4)") :
1446 ipa->address;
4aee0225 1447 if (daemon_startup_retries <= 0)
059ec3d9
PH
1448 log_write(0, LOG_MAIN|LOG_PANIC_DIE,
1449 "socket bind() to port %d for address %s failed: %s: "
1450 "daemon abandoned", ipa->port, addr, msg);
1451 log_write(0, LOG_MAIN, "socket bind() to port %d for address %s "
4aee0225
PH
1452 "failed: %s: waiting %s before trying again (%d more %s)",
1453 ipa->port, addr, msg, readconf_printtime(daemon_startup_sleep),
1454 daemon_startup_retries, (daemon_startup_retries > 1)? "tries" : "try");
1455 daemon_startup_retries--;
1456 sleep(daemon_startup_sleep);
059ec3d9
PH
1457 }
1458
1459 DEBUG(D_any)
1460 {
1461 if (wildcard)
1462 debug_printf("listening on all interfaces (IPv%c) port %d\n",
1463 (af == AF_INET6)? '6' : '4', ipa->port);
1464 else
1465 debug_printf("listening on %s port %d\n", ipa->address, ipa->port);
1466 }
1467
1468 /* Start listening on the bound socket, establishing the maximum backlog of
1469 connections that is allowed. On success, continue to the next address. */
1470
1471 if (listen(listen_sockets[sk], smtp_connect_backlog) >= 0) continue;
1472
1473 /* Listening has failed. In an IPv6 environment, as for bind(), if listen()
1474 fails with the error EADDRINUSE and we are doing IPv4 wildcard listening
1475 and there was a previous successful IPv6 wildcard listen on the same port,
1476 we want to ignore the error on the grounds that we must be in a system
1477 where the IPv6 socket accepts both kinds of call. */
1478
1479 if (!check_special_case(errno, addresses, ipa, TRUE))
1480 log_write(0, LOG_PANIC_DIE, "listen() failed on interface %s: %s",
1481 wildcard? ((af == AF_INET6)? US"(any IPv6)" : US"(any IPv4)") :
1482 ipa->address,
1483 strerror(errno));
1484
1485 DEBUG(D_any) debug_printf("wildcard IPv4 listen() failed after IPv6 "
1486 "listen() success; EADDRINUSE ignored\n");
f1e894f3 1487 (void)close(listen_sockets[sk]);
059ec3d9
PH
1488
1489 /* Come here if there has been a problem with the socket which we
1490 are going to ignore. We remove the address from the chain, and back up the
1491 counts. */
1492
1493 SKIP_SOCKET:
1494 sk--; /* Back up the count */
1495 listen_socket_count--; /* Reduce the total */
1496 if (ipa == addresses) addresses = ipa->next; else
1497 {
1498 for (ipa2 = addresses; ipa2->next != ipa; ipa2 = ipa2->next);
1499 ipa2->next = ipa->next;
1500 ipa = ipa2;
1501 }
1502 } /* End of bind/listen loop for each address */
1503 } /* End of setup for listening */
1504
1505
1506/* If we are not listening, we want to write a pid file only if -oP was
1507explicitly given. */
1508
1509else if (override_pid_file_path == NULL) write_pid = FALSE;
1510
1511/* Write the pid to a known file for assistance in identification, if required.
1512We do this before giving up root privilege, because on some systems it is
1513necessary to be root in order to write into the pid file directory. There's
1514nothing to stop multiple daemons running, as long as no more than one listens
1515on a given TCP/IP port on the same interface(s). However, in these
1516circumstances it gets far too complicated to mess with pid file names
1517automatically. Consequently, Exim 4 writes a pid file only
1518
1519 (a) When running in the test harness, or
1520 (b) When -bd is used and -oX is not used, or
1521 (c) When -oP is used to supply a path.
1522
1523The variable daemon_write_pid is used to control this. */
1524
1525if (running_in_test_harness || write_pid)
1526 {
1527 FILE *f;
1528
1529 if (override_pid_file_path != NULL)
1530 pid_file_path = override_pid_file_path;
1531
1532 if (pid_file_path[0] == 0)
1533 pid_file_path = string_sprintf("%s/exim-daemon.pid", spool_directory);
1534
2632889e 1535 f = modefopen(pid_file_path, "wb", 0644);
059ec3d9
PH
1536 if (f != NULL)
1537 {
ff790e47 1538 (void)fprintf(f, "%d\n", (int)getpid());
ff790e47 1539 (void)fclose(f);
059ec3d9
PH
1540 DEBUG(D_any) debug_printf("pid written to %s\n", pid_file_path);
1541 }
1542 else
1543 {
1544 DEBUG(D_any)
1545 debug_printf("%s\n", string_open_failed(errno, "pid file %s",
1546 pid_file_path));
1547 }
1548 }
1549
1550/* Set up the handler for SIGHUP, which causes a restart of the daemon. */
1551
1552sighup_seen = FALSE;
1553signal(SIGHUP, sighup_handler);
1554
1555/* Give up root privilege at this point (assuming that exim_uid and exim_gid
1556are not root). The third argument controls the running of initgroups().
1557Normally we do this, in order to set up the groups for the Exim user. However,
1558if we are not root at this time - some odd installations run that way - we
1559cannot do this. */
1560
1561exim_setugid(exim_uid, exim_gid, geteuid()==root_uid, US"running as a daemon");
1562
ebeaf996
PH
1563/* Update the originator_xxx fields so that received messages as listed as
1564coming from Exim, not whoever started the daemon. */
1565
1566originator_uid = exim_uid;
1567originator_gid = exim_gid;
1568originator_login = ((pw = getpwuid(exim_uid)) != NULL)?
1569 string_copy_malloc(US pw->pw_name) : US"exim";
1570
059ec3d9
PH
1571/* Get somewhere to keep the list of queue-runner pids if we are keeping track
1572of them (and also if we are doing queue runs). */
1573
1574if (queue_interval > 0 && queue_run_max > 0)
1575 {
1576 int i;
1577 queue_pid_slots = store_get(queue_run_max * sizeof(pid_t));
1578 for (i = 0; i < queue_run_max; i++) queue_pid_slots[i] = 0;
1579 }
1580
1581/* Set up the handler for termination of child processes. */
1582
1583sigchld_seen = FALSE;
7d468ab8 1584os_non_restarting_signal(SIGCHLD, main_sigchld_handler);
059ec3d9
PH
1585
1586/* If we are to run the queue periodically, pretend the alarm has just gone
1587off. This will cause the first queue-runner to get kicked off straight away. */
1588
1589sigalrm_seen = (queue_interval > 0);
1590
1591/* Log the start up of a daemon - at least one of listening or queue running
1592must be set up. */
1593
9ee44efb
PP
1594if (inetd_wait_mode)
1595 {
1596 uschar *p = big_buffer;
1597
1598 if (inetd_wait_timeout >= 0)
1599 sprintf(CS p, "terminating after %d seconds", inetd_wait_timeout);
1600 else
1601 sprintf(CS p, "with no wait timeout");
1602
1603 log_write(0, LOG_MAIN,
1604 "exim %s daemon started: pid=%d, launched with listening socket, %s",
1605 version_string, getpid(), big_buffer);
1606 set_process_info("daemon: pre-listening socket");
1607
1608 /* set up the timeout logic */
1609 sigalrm_seen = 1;
1610 }
1611
1612else if (daemon_listen)
059ec3d9
PH
1613 {
1614 int i, j;
1615 int smtp_ports = 0;
1616 int smtps_ports = 0;
1617 ip_address_item *ipa;
1618 uschar *p = big_buffer;
1619 uschar *qinfo = (queue_interval > 0)?
1620 string_sprintf("-q%s", readconf_printtime(queue_interval))
1621 :
1622 US"no queue runs";
1623
1624 /* Build a list of listening addresses in big_buffer, but limit it to 10
1625 items. The style is for backwards compatibility.
1626
1627 It is now possible to have some ports listening for SMTPS (the old,
1628 deprecated protocol that starts TLS without using STARTTLS), and others
1629 listening for standard SMTP. Keep their listings separate. */
1630
1631 for (j = 0; j < 2; j++)
1632 {
1633 for (i = 0, ipa = addresses; i < 10 && ipa != NULL; i++, ipa = ipa->next)
1634 {
1635 /* First time round, look for SMTP ports; second time round, look for
1636 SMTPS ports. For the first one of each, insert leading text. */
1637
1638 if (host_is_tls_on_connect_port(ipa->port) == (j > 0))
1639 {
1640 if (j == 0)
1641 {
1642 if (smtp_ports++ == 0)
1643 {
1644 memcpy(p, "SMTP on", 8);
1645 p += 7;
1646 }
1647 }
1648 else
1649 {
1650 if (smtps_ports++ == 0)
1651 {
1652 (void)sprintf(CS p, "%sSMTPS on",
1653 (smtp_ports == 0)? "":" and for ");
1654 while (*p != 0) p++;
1655 }
1656 }
1657
1658 /* Now the information about the port (and sometimes interface) */
1659
1660 if (ipa->address[0] == ':' && ipa->address[1] == 0)
1661 {
1662 if (ipa->next != NULL && ipa->next->address[0] == 0 &&
1663 ipa->next->port == ipa->port)
1664 {
1665 (void)sprintf(CS p, " port %d (IPv6 and IPv4)", ipa->port);
1666 ipa = ipa->next;
1667 }
1668 else if (ipa->v6_include_v4)
1669 (void)sprintf(CS p, " port %d (IPv6 with IPv4)", ipa->port);
1670 else
1671 (void)sprintf(CS p, " port %d (IPv6)", ipa->port);
1672 }
1673 else if (ipa->address[0] == 0)
1674 (void)sprintf(CS p, " port %d (IPv4)", ipa->port);
1675 else
1676 (void)sprintf(CS p, " [%s]:%d", ipa->address, ipa->port);
1677 while (*p != 0) p++;
1678 }
1679 }
1680
1681 if (ipa != NULL)
1682 {
1683 memcpy(p, " ...", 5);
1684 p += 4;
1685 }
1686 }
1687
1688 log_write(0, LOG_MAIN,
1689 "exim %s daemon started: pid=%d, %s, listening for %s",
1690 version_string, getpid(), qinfo, big_buffer);
1691 set_process_info("daemon: %s, listening for %s", qinfo, big_buffer);
1692 }
1693
1694else
1695 {
1696 log_write(0, LOG_MAIN,
1697 "exim %s daemon started: pid=%d, -q%s, not listening for SMTP",
1698 version_string, getpid(), readconf_printtime(queue_interval));
1699 set_process_info("daemon: -q%s, not listening",
1700 readconf_printtime(queue_interval));
1701 }
1702
476be7e2
JH
1703/* Do any work it might be useful to amortize over our children
1704(eg: compile regex) */
1705
1706deliver_init();
1707dns_pattern_init();
1708
1709#ifdef WITH_CONTENT_SCAN
1710malware_init();
1711#endif
059ec3d9
PH
1712
1713/* Close the log so it can be renamed and moved. In the few cases below where
1714this long-running process writes to the log (always exceptional conditions), it
1715closes the log afterwards, for the same reason. */
1716
1717log_close_all();
1718
1719DEBUG(D_any) debug_print_ids(US"daemon running with");
1720
1721/* Any messages accepted via this route are going to be SMTP. */
1722
1723smtp_input = TRUE;
1724
1725/* Enter the never-ending loop... */
1726
1727for (;;)
1728 {
1729 #if HAVE_IPV6
1730 struct sockaddr_in6 accepted;
1731 #else
1732 struct sockaddr_in accepted;
1733 #endif
1734
cf73943b 1735 EXIM_SOCKLEN_T len;
059ec3d9
PH
1736 pid_t pid;
1737
1738 /* This code is placed first in the loop, so that it gets obeyed at the
9ee44efb
PP
1739 start, before the first wait, for the queue-runner case, so that the first
1740 one can be started immediately.
1741
1742 The other option is that we have an inetd wait timeout specified to -bw. */
059ec3d9
PH
1743
1744 if (sigalrm_seen)
1745 {
9ee44efb
PP
1746 if (inetd_wait_timeout > 0)
1747 {
1748 time_t resignal_interval = inetd_wait_timeout;
1749
1750 if (last_connection_time == (time_t)0)
1751 {
1752 DEBUG(D_any)
1753 debug_printf("inetd wait timeout expired, but still not seen first message, ignoring\n");
1754 }
1755 else
1756 {
1757 time_t now = time(NULL);
1758 if (now == (time_t)-1)
1759 {
1760 DEBUG(D_any) debug_printf("failed to get time: %s\n", strerror(errno));
1761 }
1762 else
1763 {
1764 if ((now - last_connection_time) >= inetd_wait_timeout)
1765 {
1766 DEBUG(D_any)
1767 debug_printf("inetd wait timeout %d expired, ending daemon\n",
1768 inetd_wait_timeout);
1769 log_write(0, LOG_MAIN, "exim %s daemon terminating, inetd wait timeout reached.\n",
1770 version_string);
1771 exit(EXIT_SUCCESS);
1772 }
1773 else
1774 {
1775 resignal_interval -= (now - last_connection_time);
1776 }
1777 }
1778 }
059ec3d9 1779
9ee44efb
PP
1780 sigalrm_seen = FALSE;
1781 alarm(resignal_interval);
1782 }
059ec3d9 1783
9ee44efb 1784 else
059ec3d9 1785 {
9ee44efb 1786 DEBUG(D_any) debug_printf("SIGALRM received\n");
8e669ac1 1787
9ee44efb
PP
1788 /* Do a full queue run in a child process, if required, unless we already
1789 have enough queue runners on the go. If we are not running as root, a
1790 re-exec is required. */
059ec3d9 1791
9ee44efb
PP
1792 if (queue_interval > 0 &&
1793 (queue_run_max <= 0 || queue_run_count < queue_run_max))
1794 {
1795 if ((pid = fork()) == 0)
1796 {
1797 int sk;
3d235903 1798
9ee44efb
PP
1799 DEBUG(D_any) debug_printf("Starting queue-runner: pid %d\n",
1800 (int)getpid());
8e669ac1 1801
9ee44efb
PP
1802 /* Disable debugging if it's required only for the daemon process. We
1803 leave the above message, because it ties up with the "child ended"
1804 debugging messages. */
059ec3d9 1805
9ee44efb 1806 if (debug_daemon) debug_selector = 0;
059ec3d9 1807
9ee44efb 1808 /* Close any open listening sockets in the child */
059ec3d9 1809
9ee44efb
PP
1810 for (sk = 0; sk < listen_socket_count; sk++)
1811 (void)close(listen_sockets[sk]);
059ec3d9 1812
9ee44efb 1813 /* Reset SIGHUP and SIGCHLD in the child in both cases. */
059ec3d9 1814
9ee44efb
PP
1815 signal(SIGHUP, SIG_DFL);
1816 signal(SIGCHLD, SIG_DFL);
059ec3d9 1817
9ee44efb
PP
1818 /* Re-exec if privilege has been given up, unless deliver_drop_
1819 privilege is set. Reset SIGALRM before exec(). */
4fbcfc2e 1820
9ee44efb 1821 if (geteuid() != root_uid && !deliver_drop_privilege)
4fbcfc2e 1822 {
9ee44efb
PP
1823 uschar opt[8];
1824 uschar *p = opt;
1825 uschar *extra[5];
1826 int extracount = 1;
1827
1828 signal(SIGALRM, SIG_DFL);
1829 *p++ = '-';
1830 *p++ = 'q';
1831 if (queue_2stage) *p++ = 'q';
1832 if (queue_run_first_delivery) *p++ = 'i';
1833 if (queue_run_force) *p++ = 'f';
1834 if (deliver_force_thaw) *p++ = 'f';
1835 if (queue_run_local) *p++ = 'l';
1836 *p = 0;
1837 extra[0] = opt;
1838
1839 /* If -R or -S were on the original command line, ensure they get
1840 passed on. */
1841
1842 if (deliver_selectstring != NULL)
1843 {
1844 extra[extracount++] = deliver_selectstring_regex? US"-Rr" : US"-R";
1845 extra[extracount++] = deliver_selectstring;
1846 }
1847
1848 if (deliver_selectstring_sender != NULL)
1849 {
1850 extra[extracount++] = deliver_selectstring_sender_regex?
1851 US"-Sr" : US"-S";
1852 extra[extracount++] = deliver_selectstring_sender;
1853 }
1854
1855 /* Overlay this process with a new execution. */
1856
1857 (void)child_exec_exim(CEE_EXEC_PANIC, FALSE, NULL, TRUE, extracount,
1858 extra[0], extra[1], extra[2], extra[3], extra[4]);
1859
1860 /* Control never returns here. */
4fbcfc2e
PH
1861 }
1862
9ee44efb 1863 /* No need to re-exec; SIGALRM remains set to the default handler */
059ec3d9 1864
9ee44efb
PP
1865 queue_run(NULL, NULL, FALSE);
1866 _exit(EXIT_SUCCESS);
059ec3d9
PH
1867 }
1868
9ee44efb 1869 if (pid < 0)
059ec3d9 1870 {
9ee44efb
PP
1871 log_write(0, LOG_MAIN|LOG_PANIC, "daemon: fork of queue-runner "
1872 "process failed: %s", strerror(errno));
1873 log_close_all();
1874 }
1875 else
1876 {
1877 int i;
1878 for (i = 0; i < queue_run_max; ++i)
059ec3d9 1879 {
9ee44efb
PP
1880 if (queue_pid_slots[i] <= 0)
1881 {
1882 queue_pid_slots[i] = pid;
1883 queue_run_count++;
1884 break;
1885 }
059ec3d9 1886 }
9ee44efb
PP
1887 DEBUG(D_any) debug_printf("%d queue-runner process%s running\n",
1888 queue_run_count, (queue_run_count == 1)? "" : "es");
059ec3d9 1889 }
059ec3d9 1890 }
059ec3d9 1891
9ee44efb 1892 /* Reset the alarm clock */
059ec3d9 1893
9ee44efb
PP
1894 sigalrm_seen = FALSE;
1895 alarm(queue_interval);
1896 }
1897
1898 } /* sigalrm_seen */
059ec3d9
PH
1899
1900
1901 /* Sleep till a connection happens if listening, and handle the connection if
1902 that is why we woke up. The FreeBSD operating system requires the use of
1903 select() before accept() because the latter function is not interrupted by
1904 a signal, and we want to wake up for SIGCHLD and SIGALRM signals. Some other
1905 OS do notice signals in accept() but it does no harm to have the select()
1906 in for all of them - and it won't then be a lurking problem for ports to
1907 new OS. In fact, the later addition of listening on specific interfaces only
1908 requires this way of working anyway. */
1909
1910 if (daemon_listen)
1911 {
bb6e88ff 1912 int sk, lcount, select_errno;
059ec3d9
PH
1913 int max_socket = 0;
1914 BOOL select_failed = FALSE;
1915 fd_set select_listen;
1916
1917 FD_ZERO(&select_listen);
1918 for (sk = 0; sk < listen_socket_count; sk++)
1919 {
1920 FD_SET(listen_sockets[sk], &select_listen);
1921 if (listen_sockets[sk] > max_socket) max_socket = listen_sockets[sk];
1922 }
1923
1924 DEBUG(D_any) debug_printf("Listening...\n");
8e669ac1
PH
1925
1926 /* In rare cases we may have had a SIGCHLD signal in the time between
1927 setting the handler (below) and getting back here. If so, pretend that the
7d468ab8 1928 select() was interrupted so that we reap the child. This might still leave
8e669ac1 1929 a small window when a SIGCHLD could get lost. However, since we use SIGCHLD
7d468ab8
PH
1930 only to do the reaping more quickly, it shouldn't result in anything other
1931 than a delay until something else causes a wake-up. */
1932
1933 if (sigchld_seen)
1934 {
1935 lcount = -1;
8e669ac1 1936 errno = EINTR;
7d468ab8
PH
1937 }
1938 else
8e669ac1 1939 {
7d468ab8
PH
1940 lcount = select(max_socket + 1, (SELECT_ARG2_TYPE *)&select_listen,
1941 NULL, NULL, NULL);
8e669ac1 1942 }
059ec3d9 1943
7d468ab8 1944 if (lcount < 0)
059ec3d9
PH
1945 {
1946 select_failed = TRUE;
1947 lcount = 1;
1948 }
8e669ac1
PH
1949
1950 /* Clean up any subprocesses that may have terminated. We need to do this
1951 here so that smtp_accept_max_per_host works when a connection to that host
1952 has completed, and we are about to accept a new one. When this code was
1953 later in the sequence, a new connection could be rejected, even though an
1954 old one had just finished. Preserve the errno from any select() failure for
bb6e88ff 1955 the use of the common select/accept error processing below. */
8e669ac1 1956
bb6e88ff
PH
1957 select_errno = errno;
1958 handle_ending_processes();
8e669ac1
PH
1959 errno = select_errno;
1960
059ec3d9 1961 /* Loop for all the sockets that are currently ready to go. If select
7d468ab8
PH
1962 actually failed, we have set the count to 1 and select_failed=TRUE, so as
1963 to use the common error code for select/accept below. */
059ec3d9
PH
1964
1965 while (lcount-- > 0)
1966 {
1967 int accept_socket = -1;
1968 if (!select_failed)
1969 {
1970 for (sk = 0; sk < listen_socket_count; sk++)
1971 {
1972 if (FD_ISSET(listen_sockets[sk], &select_listen))
1973 {
cf73943b 1974 len = sizeof(accepted);
059ec3d9
PH
1975 accept_socket = accept(listen_sockets[sk],
1976 (struct sockaddr *)&accepted, &len);
1977 FD_CLR(listen_sockets[sk], &select_listen);
1978 break;
1979 }
1980 }
1981 }
1982
1983 /* If select or accept has failed and this was not caused by an
1984 interruption, log the incident and try again. With asymmetric TCP/IP
1985 routing errors such as "No route to network" have been seen here. Also
1986 "connection reset by peer" has been seen. These cannot be classed as
1987 disastrous errors, but they could fill up a lot of log. The code in smail
1988 crashes the daemon after 10 successive failures of accept, on the grounds
1989 that some OS fail continuously. Exim originally followed suit, but this
1990 appears to have caused problems. Now it just keeps going, but instead of
1991 logging each error, it batches them up when they are continuous. */
1992
1993 if (accept_socket < 0 && errno != EINTR)
1994 {
1995 if (accept_retry_count == 0)
1996 {
1997 accept_retry_errno = errno;
1998 accept_retry_select_failed = select_failed;
1999 }
2000 else
2001 {
2002 if (errno != accept_retry_errno ||
2003 select_failed != accept_retry_select_failed ||
2004 accept_retry_count >= 50)
2005 {
2006 log_write(0, LOG_MAIN | ((accept_retry_count >= 50)? LOG_PANIC : 0),
2007 "%d %s() failure%s: %s",
2008 accept_retry_count,
2009 accept_retry_select_failed? "select" : "accept",
2010 (accept_retry_count == 1)? "" : "s",
2011 strerror(accept_retry_errno));
2012 log_close_all();
2013 accept_retry_count = 0;
2014 accept_retry_errno = errno;
2015 accept_retry_select_failed = select_failed;
2016 }
2017 }
2018 accept_retry_count++;
2019 }
2020
2021 else
2022 {
2023 if (accept_retry_count > 0)
2024 {
2025 log_write(0, LOG_MAIN, "%d %s() failure%s: %s",
2026 accept_retry_count,
2027 accept_retry_select_failed? "select" : "accept",
2028 (accept_retry_count == 1)? "" : "s",
2029 strerror(accept_retry_errno));
2030 log_close_all();
2031 accept_retry_count = 0;
2032 }
2033 }
2034
2035 /* If select/accept succeeded, deal with the connection. */
2036
2037 if (accept_socket >= 0)
9ee44efb
PP
2038 {
2039 if (inetd_wait_timeout)
2040 last_connection_time = time(NULL);
059ec3d9
PH
2041 handle_smtp_call(listen_sockets, listen_socket_count, accept_socket,
2042 (struct sockaddr *)&accepted);
9ee44efb 2043 }
059ec3d9
PH
2044 }
2045 }
2046
2047 /* If not listening, then just sleep for the queue interval. If we woke
2048 up early the last time for some other signal, it won't matter because
2049 the alarm signal will wake at the right time. This code originally used
2050 sleep() but it turns out that on the FreeBSD system, sleep() is not inter-
2051 rupted by signals, so it wasn't waking up for SIGALRM or SIGCHLD. Luckily
2052 select() can be used as an interruptible sleep() on all versions of Unix. */
2053
2054 else
2055 {
2056 struct timeval tv;
2057 tv.tv_sec = queue_interval;
2058 tv.tv_usec = 0;
2059 select(0, NULL, NULL, NULL, &tv);
8e669ac1 2060 handle_ending_processes();
059ec3d9
PH
2061 }
2062
2063 /* Re-enable the SIGCHLD handler if it has been run. It can't do it
2064 for itself, because it isn't doing the waiting itself. */
2065
2066 if (sigchld_seen)
2067 {
2068 sigchld_seen = FALSE;
7d468ab8 2069 os_non_restarting_signal(SIGCHLD, main_sigchld_handler);
059ec3d9
PH
2070 }
2071
2072 /* Handle being woken by SIGHUP. We know at this point that the result
2073 of accept() has been dealt with, so we can re-exec exim safely, first
2074 closing the listening sockets so that they can be reused. Cancel any pending
2075 alarm in case it is just about to go off, and set SIGHUP to be ignored so
2076 that another HUP in quick succession doesn't clobber the new daemon before it
2077 gets going. All log files get closed by the close-on-exec flag; however, if
2078 the exec fails, we need to close the logs. */
2079
2080 if (sighup_seen)
2081 {
2082 int sk;
2083 log_write(0, LOG_MAIN, "pid %d: SIGHUP received: re-exec daemon",
2084 getpid());
f1e894f3
PH
2085 for (sk = 0; sk < listen_socket_count; sk++)
2086 (void)close(listen_sockets[sk]);
059ec3d9
PH
2087 alarm(0);
2088 signal(SIGHUP, SIG_IGN);
2089 sighup_argv[0] = exim_path;
2090 exim_nullstd();
2091 execv(CS exim_path, (char *const *)sighup_argv);
2092 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "pid %d: exec of %s failed: %s",
2093 getpid(), exim_path, strerror(errno));
2094 log_close_all();
2095 }
2096
2097 } /* End of main loop */
2098
2099/* Control never reaches here */
2100}
2101
071c51f7
JH
2102/* vi: aw ai sw=2
2103*/
059ec3d9 2104/* End of exim_daemon.c */