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7d468ab8 | 1 | /* $Cambridge: exim/src/src/daemon.c,v 1.3 2004/11/11 16:03:47 ph10 Exp $ */ |
059ec3d9 PH |
2 | |
3 | /************************************************* | |
4 | * Exim - an Internet mail transport agent * | |
5 | *************************************************/ | |
6 | ||
7 | /* Copyright (c) University of Cambridge 1995 - 2004 */ | |
8 | /* See the file NOTICE for conditions of use and distribution. */ | |
9 | ||
10 | /* Functions concerned with running Exim as a daemon */ | |
11 | ||
12 | ||
13 | #include "exim.h" | |
14 | ||
15 | ||
16 | /* Structure for holding data for each SMTP connection */ | |
17 | ||
18 | typedef struct smtp_slot { | |
19 | pid_t pid; /* pid of the spawned reception process */ | |
20 | uschar *host_address; /* address of the client host */ | |
21 | } smtp_slot; | |
22 | ||
23 | /* An empty slot for initializing (Standard C does not allow constructor | |
24 | expressions in assigments except as initializers in declarations). */ | |
25 | ||
26 | static smtp_slot empty_smtp_slot = { 0, NULL }; | |
27 | ||
28 | ||
29 | ||
30 | /************************************************* | |
31 | * Local static variables * | |
32 | *************************************************/ | |
33 | ||
34 | static volatile BOOL sigchld_seen; | |
35 | static volatile BOOL sighup_seen; | |
36 | ||
37 | static int accept_retry_count = 0; | |
38 | static int accept_retry_errno; | |
39 | static BOOL accept_retry_select_failed; | |
40 | ||
41 | static int queue_run_count = 0; | |
42 | static pid_t *queue_pid_slots; | |
43 | static smtp_slot *smtp_slots; | |
44 | ||
45 | static BOOL write_pid = TRUE; | |
46 | ||
47 | ||
48 | ||
49 | /************************************************* | |
50 | * SIGHUP Handler * | |
51 | *************************************************/ | |
52 | ||
53 | /* All this handler does is to set a flag and re-enable the signal. | |
54 | ||
55 | Argument: the signal number | |
56 | Returns: nothing | |
57 | */ | |
58 | ||
59 | static void | |
60 | sighup_handler(int sig) | |
61 | { | |
62 | sig = sig; /* Keep picky compilers happy */ | |
63 | sighup_seen = TRUE; | |
64 | signal(SIGHUP, sighup_handler); | |
65 | } | |
66 | ||
67 | ||
68 | ||
69 | /************************************************* | |
70 | * SIGCHLD handler for main daemon process * | |
71 | *************************************************/ | |
72 | ||
73 | /* Don't re-enable the handler here, since we aren't doing the | |
74 | waiting here. If the signal is re-enabled, there will just be an | |
75 | infinite sequence of calls to this handler. The SIGCHLD signal is | |
76 | used just as a means of waking up the daemon so that it notices | |
77 | terminated subprocesses as soon as possible. | |
78 | ||
79 | Argument: the signal number | |
80 | Returns: nothing | |
81 | */ | |
82 | ||
83 | static void | |
84 | main_sigchld_handler(int sig) | |
85 | { | |
86 | sig = sig; /* Keep picky compilers happy */ | |
7d468ab8 | 87 | os_non_restarting_signal(SIGCHLD, SIG_DFL); |
059ec3d9 | 88 | sigchld_seen = TRUE; |
059ec3d9 PH |
89 | } |
90 | ||
91 | ||
92 | ||
93 | ||
94 | /************************************************* | |
95 | * Unexpected errors in SMTP calls * | |
96 | *************************************************/ | |
97 | ||
98 | /* This function just saves a bit of repetitious coding. | |
99 | ||
100 | Arguments: | |
101 | log_msg Text of message to be logged | |
102 | smtp_msg Text of SMTP error message | |
103 | was_errno The failing errno | |
104 | ||
105 | Returns: nothing | |
106 | */ | |
107 | ||
108 | static void | |
109 | never_error(uschar *log_msg, uschar *smtp_msg, int was_errno) | |
110 | { | |
111 | uschar *emsg = (was_errno <= 0)? US"" : | |
112 | string_sprintf(": %s", strerror(was_errno)); | |
113 | log_write(0, LOG_MAIN|LOG_PANIC, "%s%s", log_msg, emsg); | |
114 | if (smtp_out != NULL) smtp_printf("421 %s\r\n", smtp_msg); | |
115 | } | |
116 | ||
117 | ||
118 | ||
119 | ||
120 | /************************************************* | |
121 | * Handle a connected SMTP call * | |
122 | *************************************************/ | |
123 | ||
124 | /* This function is called when an SMTP connection has been accepted. | |
125 | If there are too many, give an error message and close down. Otherwise | |
126 | spin off a sub-process to handle the call. The list of listening sockets | |
127 | is required so that they can be closed in the sub-process. Take care not to | |
128 | leak store in this process - reset the stacking pool at the end. | |
129 | ||
130 | Arguments: | |
131 | listen_sockets sockets which are listening for incoming calls | |
132 | listen_socket_count count of listening sockets | |
133 | accept_socket socket of the current accepted call | |
134 | accepted socket information about the current call | |
135 | ||
136 | Returns: nothing | |
137 | */ | |
138 | ||
139 | static void | |
140 | handle_smtp_call(int *listen_sockets, int listen_socket_count, | |
141 | int accept_socket, struct sockaddr *accepted) | |
142 | { | |
143 | pid_t pid; | |
144 | union sockaddr_46 interface_sockaddr; | |
145 | SOCKLEN_T ifsize = sizeof(interface_sockaddr); | |
146 | int dup_accept_socket = -1; | |
147 | int max_for_this_host = 0; | |
148 | int wfsize = 0; | |
149 | int wfptr = 0; | |
150 | int use_log_write_selector = log_write_selector; | |
151 | uschar *whofrom = NULL; | |
152 | ||
153 | void *reset_point = store_get(0); | |
154 | ||
155 | /* Make the address available in ASCII representation, and also fish out | |
156 | the remote port. */ | |
157 | ||
158 | sender_host_address = host_ntoa(-1, accepted, NULL, &sender_host_port); | |
159 | DEBUG(D_any) debug_printf("Connection request from %s port %d\n", | |
160 | sender_host_address, sender_host_port); | |
161 | ||
162 | /* Set up the output stream, check the socket has duplicated, and set up the | |
163 | input stream. These operations fail only the exceptional circumstances. Note | |
164 | that never_error() won't use smtp_out if it is NULL. */ | |
165 | ||
166 | smtp_out = fdopen(accept_socket, "wb"); | |
167 | if (smtp_out == NULL) | |
168 | { | |
169 | never_error(US"daemon: fdopen() for smtp_out failed", US"", errno); | |
170 | goto ERROR_RETURN; | |
171 | } | |
172 | ||
173 | dup_accept_socket = dup(accept_socket); | |
174 | if (dup_accept_socket < 0) | |
175 | { | |
176 | never_error(US"daemon: couldn't dup socket descriptor", | |
177 | US"Connection setup failed", errno); | |
178 | goto ERROR_RETURN; | |
179 | } | |
180 | ||
181 | smtp_in = fdopen(dup_accept_socket, "rb"); | |
182 | if (smtp_in == NULL) | |
183 | { | |
184 | never_error(US"daemon: fdopen() for smtp_in failed", | |
185 | US"Connection setup failed", errno); | |
186 | goto ERROR_RETURN; | |
187 | } | |
188 | ||
189 | /* Get the data for the local interface address. */ | |
190 | ||
191 | if (getsockname(accept_socket, (struct sockaddr *)(&interface_sockaddr), | |
192 | &ifsize) < 0) | |
193 | { | |
194 | log_write(0, LOG_MAIN|LOG_PANIC, "getsockname() failed: %s", | |
195 | strerror(errno)); | |
196 | smtp_printf("421 Local problem: getsockname() failed; please try again later\r\n"); | |
197 | goto ERROR_RETURN; | |
198 | } | |
199 | ||
200 | interface_address = host_ntoa(-1, &interface_sockaddr, NULL, &interface_port); | |
201 | DEBUG(D_interface) debug_printf("interface address=%s port=%d\n", | |
202 | interface_address, interface_port); | |
203 | ||
204 | /* Build a string identifying the remote host and, if requested, the port and | |
205 | the local interface data. This is for logging; at the end of this function the | |
206 | memory is reclaimed. */ | |
207 | ||
208 | whofrom = string_append(whofrom, &wfsize, &wfptr, 3, "[", sender_host_address, "]"); | |
209 | ||
210 | if ((log_extra_selector & LX_incoming_port) != 0) | |
211 | whofrom = string_append(whofrom, &wfsize, &wfptr, 2, ":", string_sprintf("%d", | |
212 | sender_host_port)); | |
213 | ||
214 | if ((log_extra_selector & LX_incoming_interface) != 0) | |
215 | whofrom = string_append(whofrom, &wfsize, &wfptr, 4, " I=[", | |
216 | interface_address, "]:", string_sprintf("%d", interface_port)); | |
217 | ||
218 | whofrom[wfptr] = 0; /* Terminate the newly-built string */ | |
219 | ||
220 | /* Check maximum number of connections. We do not check for reserved | |
221 | connections or unacceptable hosts here. That is done in the subprocess because | |
222 | it might take some time. */ | |
223 | ||
224 | if (smtp_accept_max > 0 && smtp_accept_count >= smtp_accept_max) | |
225 | { | |
226 | DEBUG(D_any) debug_printf("rejecting SMTP connection: count=%d max=%d\n", | |
227 | smtp_accept_count, smtp_accept_max); | |
228 | smtp_printf("421 Too many concurrent SMTP connections; " | |
229 | "please try again later.\r\n"); | |
230 | log_write(L_connection_reject, | |
231 | LOG_MAIN, "Connection from %s refused: too many connections", | |
232 | whofrom); | |
233 | goto ERROR_RETURN; | |
234 | } | |
235 | ||
236 | /* If a load limit above which only reserved hosts are acceptable is defined, | |
237 | get the load average here, and if there are in fact no reserved hosts, do | |
238 | the test right away (saves a fork). If there are hosts, do the check in the | |
239 | subprocess because it might take time. */ | |
240 | ||
241 | if (smtp_load_reserve >= 0) | |
242 | { | |
243 | load_average = os_getloadavg(); | |
244 | if (smtp_reserve_hosts == NULL && load_average > smtp_load_reserve) | |
245 | { | |
246 | DEBUG(D_any) debug_printf("rejecting SMTP connection: load average = %.2f\n", | |
247 | (double)load_average/1000.0); | |
248 | smtp_printf("421 Too much load; please try again later.\r\n"); | |
249 | log_write(L_connection_reject, | |
250 | LOG_MAIN, "Connection from %s refused: load average = %.2f", | |
251 | whofrom, (double)load_average/1000.0); | |
252 | goto ERROR_RETURN; | |
253 | } | |
254 | } | |
255 | ||
256 | /* Check that one specific host (strictly, IP address) is not hogging | |
257 | resources. This is done here to prevent a denial of service attack by someone | |
258 | forcing you to fork lots of times before denying service. The value of | |
259 | smtp_accept_max_per_host is a string which is expanded. This makes it possible | |
260 | to provide host-specific limits according to $sender_host address, but because | |
261 | this is in the daemon mainline, only fast expansions (such as inline address | |
262 | checks) should be used. The documentation is full of warnings. */ | |
263 | ||
264 | if (smtp_accept_max_per_host != NULL) | |
265 | { | |
266 | uschar *expanded = expand_string(smtp_accept_max_per_host); | |
267 | if (expanded == NULL) | |
268 | { | |
269 | if (!expand_string_forcedfail) | |
270 | log_write(0, LOG_MAIN|LOG_PANIC, "expansion of smtp_accept_max_per_host " | |
271 | "failed for %s: %s", whofrom, expand_string_message); | |
272 | } | |
273 | /* For speed, interpret a decimal number inline here */ | |
274 | else | |
275 | { | |
276 | uschar *s = expanded; | |
277 | while (isdigit(*s)) | |
278 | max_for_this_host = max_for_this_host * 10 + *s++ - '0'; | |
279 | if (*s != 0) | |
280 | log_write(0, LOG_MAIN|LOG_PANIC, "expansion of smtp_accept_max_per_host " | |
281 | "for %s contains non-digit: %s", whofrom, expanded); | |
282 | } | |
283 | } | |
284 | ||
285 | /* If we have fewer connections than max_for_this_host, we can skip the tedious | |
286 | per host_address checks. Note that at this stage smtp_accept_count contains the | |
287 | count of *other* connections, not including this one. */ | |
288 | ||
289 | if ((max_for_this_host > 0) && | |
290 | (smtp_accept_count >= max_for_this_host)) | |
291 | { | |
292 | int i; | |
293 | int host_accept_count = 0; | |
294 | int other_host_count = 0; /* keep a count of non matches to optimise */ | |
295 | ||
296 | for (i = 0; i < smtp_accept_max; ++i) | |
297 | { | |
298 | if (smtp_slots[i].host_address != NULL) | |
299 | { | |
300 | if (Ustrcmp(sender_host_address, smtp_slots[i].host_address) == 0) | |
301 | host_accept_count++; | |
302 | else | |
303 | other_host_count++; | |
304 | ||
305 | /* Testing all these strings is expensive - see if we can drop out | |
306 | early, either by hitting the target, or finding there are not enough | |
307 | connections left to make the target. */ | |
308 | ||
309 | if ((host_accept_count >= max_for_this_host) || | |
310 | ((smtp_accept_count - other_host_count) < max_for_this_host)) | |
311 | break; | |
312 | } | |
313 | } | |
314 | ||
315 | if (host_accept_count >= max_for_this_host) | |
316 | { | |
317 | DEBUG(D_any) debug_printf("rejecting SMTP connection: too many from this " | |
318 | "IP address: count=%d max=%d\n", | |
319 | host_accept_count, max_for_this_host); | |
320 | smtp_printf("421 Too many concurrent SMTP connections " | |
321 | "from this IP address; please try again later.\r\n"); | |
322 | log_write(L_connection_reject, | |
323 | LOG_MAIN, "Connection from %s refused: too many connections " | |
324 | "from that IP address", whofrom); | |
325 | goto ERROR_RETURN; | |
326 | } | |
327 | } | |
328 | ||
329 | /* OK, the connection count checks have been passed. Before we can fork the | |
330 | accepting process, we must first log the connection if requested. This logging | |
331 | used to happen in the subprocess, but doing that means that the value of | |
332 | smtp_accept_count can be out of step by the time it is logged. So we have to do | |
333 | the logging here and accept the performance cost. Note that smtp_accept_count | |
334 | hasn't yet been incremented to take account of this connection. | |
335 | ||
336 | In order to minimize the cost (because this is going to happen for every | |
337 | connection), do a preliminary selector test here. This saves ploughing through | |
338 | the generalized logging code each time when the selector is false. If the | |
339 | selector is set, check whether the host is on the list for logging. If not, | |
340 | arrange to unset the selector in the subprocess. */ | |
341 | ||
342 | if ((log_write_selector & L_smtp_connection) != 0) | |
343 | { | |
344 | uschar *list = hosts_connection_nolog; | |
345 | if (list != NULL && verify_check_host(&list) == OK) | |
346 | use_log_write_selector &= ~L_smtp_connection; | |
347 | else | |
348 | log_write(L_smtp_connection, LOG_MAIN, "SMTP connection from %s " | |
349 | "(TCP/IP connection count = %d)", whofrom, smtp_accept_count + 1); | |
350 | } | |
351 | ||
352 | /* Now we can fork the accepting process; do a lookup tidy, just in case any | |
353 | expansion above did a lookup. */ | |
354 | ||
355 | search_tidyup(); | |
356 | pid = fork(); | |
357 | ||
358 | /* Handle the child process */ | |
359 | ||
360 | if (pid == 0) | |
361 | { | |
362 | int i; | |
363 | int queue_only_reason = 0; | |
364 | int old_pool = store_pool; | |
3d235903 | 365 | int save_debug_selector = debug_selector; |
059ec3d9 PH |
366 | BOOL local_queue_only; |
367 | #ifdef SA_NOCLDWAIT | |
368 | struct sigaction act; | |
369 | #endif | |
370 | ||
371 | /* May have been modified for the subprocess */ | |
372 | ||
373 | log_write_selector = use_log_write_selector; | |
374 | ||
375 | /* Get the local interface address into permanent store */ | |
376 | ||
377 | store_pool = POOL_PERM; | |
378 | interface_address = string_copy(interface_address); | |
379 | store_pool = old_pool; | |
380 | ||
381 | /* Check for a tls-on-connect port */ | |
382 | ||
383 | if (host_is_tls_on_connect_port(interface_port)) tls_on_connect = TRUE; | |
384 | ||
385 | /* Expand smtp_active_hostname if required. We do not do this any earlier, | |
386 | because it may depend on the local interface address (indeed, that is most | |
387 | likely what it depends on.) */ | |
388 | ||
389 | smtp_active_hostname = primary_hostname; | |
390 | if (raw_active_hostname != NULL) | |
391 | { | |
392 | uschar *nah = expand_string(raw_active_hostname); | |
393 | if (nah == NULL) | |
394 | { | |
395 | if (!expand_string_forcedfail) | |
396 | { | |
397 | log_write(0, LOG_MAIN|LOG_PANIC, "failed to expand \"%s\" " | |
398 | "(smtp_active_hostname): %s", raw_active_hostname, | |
399 | expand_string_message); | |
400 | smtp_printf("421 Local configuration error; " | |
401 | "please try again later.\r\n"); | |
402 | mac_smtp_fflush(); | |
403 | search_tidyup(); | |
404 | _exit(EXIT_FAILURE); | |
405 | } | |
406 | } | |
407 | else if (nah[0] != 0) smtp_active_hostname = nah; | |
408 | } | |
409 | ||
410 | /* Initialize the queueing flags */ | |
411 | ||
412 | queue_check_only(); | |
413 | local_queue_only = queue_only; | |
414 | ||
415 | /* Close the listening sockets, and set the SIGCHLD handler to SIG_IGN. | |
416 | We also attempt to set things up so that children are automatically reaped, | |
417 | but just in case this isn't available, there's a paranoid waitpid() in the | |
418 | loop too (except for systems where we are sure it isn't needed). See the more | |
419 | extensive comment before the reception loop in exim.c for a fuller | |
420 | explanation of this logic. */ | |
421 | ||
422 | for (i = 0; i < listen_socket_count; i++) close(listen_sockets[i]); | |
423 | ||
424 | #ifdef SA_NOCLDWAIT | |
425 | act.sa_handler = SIG_IGN; | |
426 | sigemptyset(&(act.sa_mask)); | |
427 | act.sa_flags = SA_NOCLDWAIT; | |
428 | sigaction(SIGCHLD, &act, NULL); | |
429 | #else | |
430 | signal(SIGCHLD, SIG_IGN); | |
431 | #endif | |
432 | ||
433 | /* Attempt to get an id from the sending machine via the RFC 1413 | |
434 | protocol. We do this in the sub-process in order not to hold up the | |
435 | main process if there is any delay. Then set up the fullhost information | |
3d235903 PH |
436 | in case there is no HELO/EHLO. |
437 | ||
438 | If debugging is enabled only for the daemon, we must turn if off while | |
439 | finding the id, but turn it on again afterwards so that information about the | |
440 | incoming connection is output. */ | |
441 | ||
442 | if (debug_daemon) debug_selector = 0; | |
059ec3d9 PH |
443 | verify_get_ident(IDENT_PORT); |
444 | host_build_sender_fullhost(); | |
3d235903 | 445 | debug_selector = save_debug_selector; |
059ec3d9 PH |
446 | |
447 | DEBUG(D_any) | |
448 | debug_printf("Process %d is handling incoming connection from %s\n", | |
449 | (int)getpid(), sender_fullhost); | |
450 | ||
3d235903 PH |
451 | /* Now disable debugging permanently if it's required only for the daemon |
452 | process. */ | |
453 | ||
454 | if (debug_daemon) debug_selector = 0; | |
455 | ||
059ec3d9 PH |
456 | /* If there are too many child processes for immediate delivery, |
457 | set the local_queue_only flag, which is initialized from the | |
458 | configured value and may therefore already be TRUE. Leave logging | |
459 | till later so it will have a message id attached. */ | |
460 | ||
461 | if (smtp_accept_queue > 0 && smtp_accept_count >= smtp_accept_queue) | |
462 | { | |
463 | local_queue_only = TRUE; | |
464 | queue_only_reason = 1; | |
465 | } | |
466 | ||
467 | /* Handle the start of the SMTP session, then loop, accepting incoming | |
468 | messages from the SMTP connection. The end will come at the QUIT command, | |
469 | when smtp_setup_msg() returns 0. A break in the connection causes the | |
470 | process to die (see accept.c). */ | |
471 | ||
472 | if (!smtp_start_session()) | |
473 | { | |
474 | mac_smtp_fflush(); | |
475 | search_tidyup(); | |
476 | _exit(EXIT_SUCCESS); | |
477 | } | |
478 | ||
479 | for (;;) | |
480 | { | |
481 | int rc; | |
482 | message_id[0] = 0; /* Clear out any previous message_id */ | |
483 | reset_point = store_get(0); /* Save current store high water point */ | |
484 | ||
485 | DEBUG(D_any) | |
486 | debug_printf("Process %d is ready for new message\n", (int)getpid()); | |
487 | ||
488 | /* Smtp_setup_msg() returns 0 on QUIT or if the call is from an | |
489 | unacceptable host or if an ACL "drop" command was triggered, -1 on | |
490 | connection lost, and +1 on validly reaching DATA. Receive_msg() almost | |
491 | always returns TRUE when smtp_input is true; just retry if no message was | |
492 | accepted (can happen for invalid message parameters). However, it can yield | |
493 | FALSE if the connection was forcibly dropped by the DATA ACL. */ | |
494 | ||
495 | if ((rc = smtp_setup_msg()) > 0) | |
496 | { | |
497 | BOOL ok = receive_msg(FALSE); | |
498 | search_tidyup(); /* Close cached databases */ | |
499 | if (!ok) /* Connection was dropped */ | |
500 | { | |
501 | mac_smtp_fflush(); | |
502 | _exit(EXIT_SUCCESS); | |
503 | } | |
504 | if (message_id[0] == 0) continue; /* No message was accepted */ | |
505 | } | |
506 | else | |
507 | { | |
508 | mac_smtp_fflush(); | |
509 | search_tidyup(); | |
510 | _exit((rc == 0)? EXIT_SUCCESS : EXIT_FAILURE); | |
511 | } | |
512 | ||
513 | /* Show the recipients when debugging */ | |
514 | ||
515 | DEBUG(D_receive) | |
516 | { | |
517 | int i; | |
518 | if (sender_address != NULL) | |
519 | debug_printf("Sender: %s\n", sender_address); | |
520 | if (recipients_list != NULL) | |
521 | { | |
522 | debug_printf("Recipients:\n"); | |
523 | for (i = 0; i < recipients_count; i++) | |
524 | debug_printf(" %s\n", recipients_list[i].address); | |
525 | } | |
526 | } | |
527 | ||
528 | /* A message has been accepted. Clean up any previous delivery processes | |
529 | that have completed and are defunct, on systems where they don't go away | |
530 | by themselves (see comments when setting SIG_IGN above). On such systems | |
531 | (if any) these delivery processes hang around after termination until | |
532 | the next message is received. */ | |
533 | ||
534 | #ifndef SIG_IGN_WORKS | |
535 | while (waitpid(-1, NULL, WNOHANG) > 0); | |
536 | #endif | |
537 | ||
538 | /* Reclaim up the store used in accepting this message */ | |
539 | ||
540 | store_reset(reset_point); | |
541 | ||
542 | /* If queue_only is set or if there are too many incoming connections in | |
543 | existence, local_queue_only will be TRUE. If it is not, check whether we | |
544 | have received too many messages in this session for immediate delivery. If | |
545 | not, and queue_only_load is set, check that the load average is below it. | |
546 | Note that, once set, local_queue_only remains set for any subsequent | |
547 | messages on the same SMTP connection. This is a deliberate choice; even | |
548 | though the load average may fall, it doesn't seem right to deliver later | |
549 | messages on the same call when not delivering earlier ones. */ | |
550 | ||
551 | if (!local_queue_only) | |
552 | { | |
553 | if (smtp_accept_queue_per_connection > 0 && | |
554 | receive_messagecount > smtp_accept_queue_per_connection) | |
555 | { | |
556 | local_queue_only = TRUE; | |
557 | queue_only_reason = 2; | |
558 | } | |
559 | else if (queue_only_load >= 0) | |
560 | { | |
561 | local_queue_only = (load_average = os_getloadavg()) > queue_only_load; | |
562 | if (local_queue_only) queue_only_reason = 3; | |
563 | } | |
564 | } | |
565 | ||
566 | /* Log the queueing here, when it will get a message id attached, but | |
567 | not if queue_only is set (case 0). */ | |
568 | ||
569 | if (local_queue_only) switch(queue_only_reason) | |
570 | { | |
571 | case 1: | |
572 | log_write(L_delay_delivery, | |
573 | LOG_MAIN, "no immediate delivery: too many connections " | |
574 | "(%d, max %d)", smtp_accept_count, smtp_accept_queue); | |
575 | break; | |
576 | ||
577 | case 2: | |
578 | log_write(L_delay_delivery, | |
579 | LOG_MAIN, "no immediate delivery: more than %d messages " | |
580 | "received in one connection", smtp_accept_queue_per_connection); | |
581 | break; | |
582 | ||
583 | case 3: | |
584 | log_write(L_delay_delivery, | |
585 | LOG_MAIN, "no immediate delivery: load average %.2f", | |
586 | (double)load_average/1000.0); | |
587 | break; | |
588 | } | |
589 | ||
590 | /* If a delivery attempt is required, spin off a new process to handle it. | |
591 | If we are not root, we have to re-exec exim unless deliveries are being | |
592 | done unprivileged. */ | |
593 | ||
594 | else if (!queue_only_policy && !deliver_freeze) | |
595 | { | |
596 | pid_t dpid; | |
597 | ||
598 | /* Before forking, ensure that the C output buffer is flushed. Otherwise | |
599 | anything that it in it will get duplicated, leading to duplicate copies | |
600 | of the pending output. */ | |
601 | ||
602 | mac_smtp_fflush(); | |
603 | ||
604 | if ((dpid = fork()) == 0) | |
605 | { | |
606 | fclose(smtp_in); | |
607 | fclose(smtp_out); | |
608 | ||
609 | /* Don't ever molest the parent's SSL connection, but do clean up | |
610 | the data structures if necessary. */ | |
611 | ||
612 | #ifdef SUPPORT_TLS | |
613 | tls_close(FALSE); | |
614 | #endif | |
615 | ||
616 | /* Reset SIGHUP and SIGCHLD in the child in both cases. */ | |
617 | ||
618 | signal(SIGHUP, SIG_DFL); | |
619 | signal(SIGCHLD, SIG_DFL); | |
620 | ||
621 | if (geteuid() != root_uid && !deliver_drop_privilege) | |
622 | { | |
623 | signal(SIGALRM, SIG_DFL); | |
624 | (void)child_exec_exim(CEE_EXEC_PANIC, FALSE, NULL, FALSE, 2, US"-Mc", | |
625 | message_id); | |
626 | /* Control does not return here. */ | |
627 | } | |
628 | ||
629 | /* No need to re-exec; SIGALRM remains set to the default handler */ | |
630 | ||
631 | (void)deliver_message(message_id, FALSE, FALSE); | |
632 | search_tidyup(); | |
633 | _exit(EXIT_SUCCESS); | |
634 | } | |
635 | ||
636 | if (dpid > 0) | |
637 | { | |
638 | DEBUG(D_any) debug_printf("forked delivery process %d\n", (int)dpid); | |
639 | } | |
640 | else | |
641 | { | |
642 | log_write(0, LOG_MAIN|LOG_PANIC, "daemon: delivery process fork " | |
643 | "failed: %s", strerror(errno)); | |
644 | } | |
645 | } | |
646 | } | |
647 | } | |
648 | ||
649 | ||
650 | /* Carrying on in the parent daemon process... Can't do much if the fork | |
651 | failed. Otherwise, keep count of the number of accepting processes and | |
652 | remember the pid for ticking off when the child completes. */ | |
653 | ||
654 | if (pid < 0) | |
655 | { | |
656 | never_error(US"daemon: accept process fork failed", US"Fork failed", errno); | |
657 | } | |
658 | else | |
659 | { | |
660 | int i; | |
661 | for (i = 0; i < smtp_accept_max; ++i) | |
662 | { | |
663 | if (smtp_slots[i].pid <= 0) | |
664 | { | |
665 | smtp_slots[i].pid = pid; | |
666 | if (smtp_accept_max_per_host != NULL) | |
667 | smtp_slots[i].host_address = string_copy_malloc(sender_host_address); | |
668 | smtp_accept_count++; | |
669 | break; | |
670 | } | |
671 | } | |
672 | DEBUG(D_any) debug_printf("%d SMTP accept process%s running\n", | |
673 | smtp_accept_count, (smtp_accept_count == 1)? "" : "es"); | |
674 | } | |
675 | ||
676 | /* Get here via goto in error cases */ | |
677 | ||
678 | ERROR_RETURN: | |
679 | ||
680 | /* Close the streams associated with the socket which will also close the | |
681 | socket fds in this process. We can't do anything if fclose() fails, but | |
682 | logging brings it to someone's attention. However, "connection reset by peer" | |
683 | isn't really a problem, so skip that one. If the streams don't exist, something | |
684 | went wrong while setting things up. Make sure the socket descriptors are | |
685 | closed, in order to drop the connection. */ | |
686 | ||
687 | if (smtp_out != NULL) | |
688 | { | |
689 | if (fclose(smtp_out) != 0 && errno != ECONNRESET) | |
690 | log_write(0, LOG_MAIN|LOG_PANIC, "daemon: fclose(smtp_out) failed: %s", | |
691 | strerror(errno)); | |
692 | smtp_out = NULL; | |
693 | } | |
694 | else close(accept_socket); | |
695 | ||
696 | if (smtp_in != NULL) | |
697 | { | |
698 | if (fclose(smtp_in) != 0 && errno != ECONNRESET) | |
699 | log_write(0, LOG_MAIN|LOG_PANIC, "daemon: fclose(smtp_in) failed: %s", | |
700 | strerror(errno)); | |
701 | smtp_in = NULL; | |
702 | } | |
703 | else close(dup_accept_socket); | |
704 | ||
705 | /* Release any store used in this process, including the store used for holding | |
706 | the incoming host address and an expanded active_hostname. */ | |
707 | ||
708 | store_reset(reset_point); | |
709 | sender_host_address = NULL; | |
710 | } | |
711 | ||
712 | ||
713 | ||
714 | ||
715 | /************************************************* | |
716 | * Check wildcard listen special cases * | |
717 | *************************************************/ | |
718 | ||
719 | /* This function is used when binding and listening on lists of addresses and | |
720 | ports. It tests for special cases of wildcard listening, when IPv4 and IPv6 | |
721 | sockets may interact in different ways in different operating systems. It is | |
722 | passed an error number, the list of listening addresses, and the current | |
723 | address. Two checks are available: for a previous wildcard IPv6 address, or for | |
724 | a following wildcard IPv4 address, in both cases on the same port. | |
725 | ||
726 | In practice, pairs of wildcard addresses should be adjacent in the address list | |
727 | because they are sorted that way below. | |
728 | ||
729 | Arguments: | |
730 | eno the error number | |
731 | addresses the list of addresses | |
732 | ipa the current IP address | |
733 | back if TRUE, check for previous wildcard IPv6 address | |
734 | if FALSE, check for a following wildcard IPv4 address | |
735 | ||
736 | Returns: TRUE or FALSE | |
737 | */ | |
738 | ||
739 | static BOOL | |
740 | check_special_case(int eno, ip_address_item *addresses, ip_address_item *ipa, | |
741 | BOOL back) | |
742 | { | |
743 | ip_address_item *ipa2; | |
744 | ||
745 | /* For the "back" case, if the failure was "address in use" for a wildcard IPv4 | |
746 | address, seek a previous IPv6 wildcard address on the same port. As it is | |
747 | previous, it must have been successfully bound and be listening. Flag it as a | |
748 | "6 including 4" listener. */ | |
749 | ||
750 | if (back) | |
751 | { | |
752 | if (eno != EADDRINUSE || ipa->address[0] != 0) return FALSE; | |
753 | for (ipa2 = addresses; ipa2 != ipa; ipa2 = ipa2->next) | |
754 | { | |
755 | if (ipa2->address[1] == 0 && ipa2->port == ipa->port) | |
756 | { | |
757 | ipa2->v6_include_v4 = TRUE; | |
758 | return TRUE; | |
759 | } | |
760 | } | |
761 | } | |
762 | ||
763 | /* For the "forward" case, if the current address is a wildcard IPv6 address, | |
764 | we seek a following wildcard IPv4 address on the same port. */ | |
765 | ||
766 | else | |
767 | { | |
768 | if (ipa->address[0] != ':' || ipa->address[1] != 0) return FALSE; | |
769 | for (ipa2 = ipa->next; ipa2 != NULL; ipa2 = ipa2->next) | |
770 | if (ipa2->address[0] == 0 && ipa->port == ipa2->port) return TRUE; | |
771 | } | |
772 | ||
773 | return FALSE; | |
774 | } | |
775 | ||
776 | ||
777 | ||
778 | ||
779 | ||
780 | ||
781 | /************************************************* | |
782 | * Exim Daemon Mainline * | |
783 | *************************************************/ | |
784 | ||
785 | /* The daemon can do two jobs, either of which is optional: | |
786 | ||
787 | (1) Listens for incoming SMTP calls and spawns off a sub-process to handle | |
788 | each one. This is requested by the -bd option, with -oX specifying the SMTP | |
789 | port on which to listen (for testing). | |
790 | ||
791 | (2) Spawns a queue-running process every so often. This is controlled by the | |
792 | -q option with a an interval time. (If no time is given, a single queue run | |
793 | is done from the main function, and control doesn't get here.) | |
794 | ||
795 | Root privilege is required in order to attach to port 25. Some systems require | |
796 | it when calling socket() rather than bind(). To cope with all cases, we run as | |
797 | root for both socket() and bind(). Some systems also require root in order to | |
798 | write to the pid file directory. This function must therefore be called as root | |
799 | if it is to work properly in all circumstances. Once the socket is bound and | |
800 | the pid file written, root privilege is given up if there is an exim uid. | |
801 | ||
802 | There are no arguments to this function, and it never returns. */ | |
803 | ||
804 | void | |
805 | daemon_go(void) | |
806 | { | |
807 | int *listen_sockets = NULL; | |
808 | int listen_socket_count = 0; | |
809 | ip_address_item *addresses = NULL; | |
810 | ||
811 | /* If any debugging options are set, turn on the D_pid bit so that all | |
812 | debugging lines get the pid added. */ | |
813 | ||
814 | DEBUG(D_any|D_v) debug_selector |= D_pid; | |
815 | ||
816 | ||
817 | /* Do the preparation for setting up a listener on one or more interfaces, and | |
818 | possible on various ports. This is controlled by the combination of | |
819 | local_interfaces (which can set IP addresses and ports) and daemon_smtp_port | |
820 | (which is a list of default ports to use for those items in local_interfaces | |
821 | that do not specify a port). The -oX command line option can be used to | |
822 | override one or both of these options. | |
823 | ||
824 | If local_interfaces is not set, the default is to listen on all interfaces. | |
825 | When it is set, it can include "all IPvx interfaces" as an item. This is useful | |
826 | when different ports are in use. | |
827 | ||
828 | It turns out that listening on all interfaces is messy in an IPv6 world, | |
829 | because several different implementation approaches have been taken. This code | |
830 | is now supposed to work with all of them. The point of difference is whether an | |
831 | IPv6 socket that is listening on all interfaces will receive incoming IPv4 | |
832 | calls or not. We also have to cope with the case when IPv6 libraries exist, but | |
833 | there is no IPv6 support in the kernel. | |
834 | ||
835 | . On Solaris, an IPv6 socket will accept IPv4 calls, and give them as mapped | |
836 | addresses. However, if an IPv4 socket is also listening on all interfaces, | |
837 | calls are directed to the appropriate socket. | |
838 | ||
839 | . On (some versions of) Linux, an IPv6 socket will accept IPv4 calls, and | |
840 | give them as mapped addresses, but an attempt also to listen on an IPv4 | |
841 | socket on all interfaces causes an error. | |
842 | ||
843 | . On OpenBSD, an IPv6 socket will not accept IPv4 calls. You have to set up | |
844 | two sockets if you want to accept both kinds of call. | |
845 | ||
846 | . FreeBSD is like OpenBSD, but it has the IPV6_V6ONLY socket option, which | |
847 | can be turned off, to make it behave like the versions of Linux described | |
848 | above. | |
849 | ||
850 | . I heard a report that the USAGI IPv6 stack for Linux has implemented | |
851 | IPV6_V6ONLY. | |
852 | ||
853 | So, what we do when IPv6 is supported is as follows: | |
854 | ||
855 | (1) After it is set up, the list of interfaces is scanned for wildcard | |
856 | addresses. If an IPv6 and an IPv4 wildcard are both found for the same | |
857 | port, the list is re-arranged so that they are together, with the IPv6 | |
858 | wildcard first. | |
859 | ||
860 | (2) If the creation of a wildcard IPv6 socket fails, we just log the error and | |
861 | carry on if an IPv4 wildcard socket for the same port follows later in the | |
862 | list. This allows Exim to carry on in the case when the kernel has no IPv6 | |
863 | support. | |
864 | ||
865 | (3) Having created an IPv6 wildcard socket, we try to set IPV6_V6ONLY if that | |
866 | option is defined. However, if setting fails, carry on regardless (but log | |
867 | the incident). | |
868 | ||
869 | (4) If binding or listening on an IPv6 wildcard socket fails, it is a serious | |
870 | error. | |
871 | ||
872 | (5) If binding or listening on an IPv4 wildcard socket fails with the error | |
873 | EADDRINUSE, and a previous interface was an IPv6 wildcard for the same | |
874 | port (which must have succeeded or we wouldn't have got this far), we | |
875 | assume we are in the situation where just a single socket is permitted, | |
876 | and ignore the error. | |
877 | ||
878 | Phew! | |
879 | ||
880 | The preparation code decodes options and sets up the relevant data. We do this | |
881 | first, so that we can return non-zero if there are any syntax errors, and also | |
882 | write to stderr. */ | |
883 | ||
884 | if (daemon_listen) | |
885 | { | |
886 | int *default_smtp_port; | |
887 | int sep; | |
888 | int pct = 0; | |
889 | uschar *s; | |
890 | uschar *list; | |
891 | uschar *local_iface_source = US"local_interfaces"; | |
892 | ip_address_item *ipa; | |
893 | ip_address_item **pipa; | |
894 | ||
895 | /* If any option requiring a load average to be available during the | |
896 | reception of a message is set, call os_getloadavg() while we are root | |
897 | for those OS for which this is necessary the first time it is called (in | |
898 | order to perform an "open" on the kernel memory file). */ | |
899 | ||
900 | #ifdef LOAD_AVG_NEEDS_ROOT | |
901 | if (queue_only_load >= 0 || smtp_load_reserve >= 0) (void)os_getloadavg(); | |
902 | #endif | |
903 | ||
904 | /* If -oX was used, disable the writing of a pid file unless -oP was | |
905 | explicitly used to force it. Then scan the string given to -oX. Any items | |
906 | that contain neither a dot nor a colon are used to override daemon_smtp_port. | |
907 | Any other items are used to override local_interfaces. */ | |
908 | ||
909 | if (override_local_interfaces != NULL) | |
910 | { | |
911 | uschar *new_smtp_port = NULL; | |
912 | uschar *new_local_interfaces = NULL; | |
913 | int portsize = 0; | |
914 | int portptr = 0; | |
915 | int ifacesize = 0; | |
916 | int ifaceptr = 0; | |
917 | ||
918 | if (override_pid_file_path == NULL) write_pid = FALSE; | |
919 | ||
920 | list = override_local_interfaces; | |
921 | sep = 0; | |
922 | while ((s = string_nextinlist(&list,&sep,big_buffer,big_buffer_size)) | |
923 | != NULL) | |
924 | { | |
925 | uschar joinstr[4]; | |
926 | uschar **ptr; | |
927 | int *sizeptr; | |
928 | int *ptrptr; | |
929 | ||
930 | if (Ustrpbrk(s, ".:") == NULL) | |
931 | { | |
932 | ptr = &new_smtp_port; | |
933 | sizeptr = &portsize; | |
934 | ptrptr = &portptr; | |
935 | } | |
936 | else | |
937 | { | |
938 | ptr = &new_local_interfaces; | |
939 | sizeptr = &ifacesize; | |
940 | ptrptr = &ifaceptr; | |
941 | } | |
942 | ||
943 | if (*ptr == NULL) | |
944 | { | |
945 | joinstr[0] = sep; | |
946 | joinstr[1] = ' '; | |
947 | *ptr = string_cat(*ptr, sizeptr, ptrptr, US"<", 1); | |
948 | } | |
949 | ||
950 | *ptr = string_cat(*ptr, sizeptr, ptrptr, joinstr, 2); | |
951 | *ptr = string_cat(*ptr, sizeptr, ptrptr, s, Ustrlen(s)); | |
952 | } | |
953 | ||
954 | if (new_smtp_port != NULL) | |
955 | { | |
956 | new_smtp_port[portptr] = 0; | |
957 | daemon_smtp_port = new_smtp_port; | |
958 | DEBUG(D_any) debug_printf("daemon_smtp_port overridden by -oX:\n %s\n", | |
959 | daemon_smtp_port); | |
960 | } | |
961 | ||
962 | if (new_local_interfaces != NULL) | |
963 | { | |
964 | new_local_interfaces[ifaceptr] = 0; | |
965 | local_interfaces = new_local_interfaces; | |
966 | local_iface_source = US"-oX data"; | |
967 | DEBUG(D_any) debug_printf("local_interfaces overridden by -oX:\n %s\n", | |
968 | local_interfaces); | |
969 | } | |
970 | } | |
971 | ||
972 | /* Create a list of default SMTP ports, to be used if local_interfaces | |
973 | contains entries without explict ports. First count the number of ports, then | |
974 | build a translated list in a vector. */ | |
975 | ||
976 | list = daemon_smtp_port; | |
977 | sep = 0; | |
978 | while ((s = string_nextinlist(&list,&sep,big_buffer,big_buffer_size)) != NULL) | |
979 | pct++; | |
980 | default_smtp_port = store_get((pct+1) * sizeof(int)); | |
981 | list = daemon_smtp_port; | |
982 | sep = 0; | |
983 | for (pct = 0; | |
984 | (s = string_nextinlist(&list,&sep,big_buffer,big_buffer_size)) != NULL; | |
985 | pct++) | |
986 | { | |
987 | if (isdigit(*s)) | |
988 | { | |
989 | uschar *end; | |
990 | default_smtp_port[pct] = Ustrtol(s, &end, 0); | |
991 | if (end != s + Ustrlen(s)) | |
992 | log_write(0, LOG_PANIC_DIE|LOG_CONFIG, "invalid SMTP port: %s", s); | |
993 | } | |
994 | else | |
995 | { | |
996 | struct servent *smtp_service = getservbyname(CS s, "tcp"); | |
997 | if (smtp_service == NULL) | |
998 | log_write(0, LOG_PANIC_DIE|LOG_CONFIG, "TCP port \"%s\" not found", s); | |
999 | default_smtp_port[pct] = ntohs(smtp_service->s_port); | |
1000 | } | |
1001 | } | |
1002 | default_smtp_port[pct] = 0; | |
1003 | ||
1004 | /* Create the list of local interfaces, possibly with ports included. This | |
1005 | list may contain references to 0.0.0.0 and ::0 as wildcards. These special | |
1006 | values are converted below. */ | |
1007 | ||
1008 | addresses = host_build_ifacelist(local_interfaces, local_iface_source); | |
1009 | ||
1010 | /* In the list of IP addresses, convert 0.0.0.0 into an empty string, and ::0 | |
1011 | into the string ":". We use these to recognize wildcards in IPv4 and IPv6. In | |
1012 | fact, many IP stacks recognize 0.0.0.0 and ::0 and handle them as wildcards | |
1013 | anyway, but we need to know which are the wildcard addresses, and the shorter | |
1014 | strings are neater. | |
1015 | ||
1016 | In the same scan, fill in missing port numbers from the default list. When | |
1017 | there is more than one item in the list, extra items are created. */ | |
1018 | ||
1019 | for (ipa = addresses; ipa != NULL; ipa = ipa->next) | |
1020 | { | |
1021 | int i; | |
1022 | ||
1023 | if (Ustrcmp(ipa->address, "0.0.0.0") == 0) ipa->address[0] = 0; | |
1024 | else if (Ustrcmp(ipa->address, "::0") == 0) | |
1025 | { | |
1026 | ipa->address[0] = ':'; | |
1027 | ipa->address[1] = 0; | |
1028 | } | |
1029 | ||
1030 | if (ipa->port > 0) continue; | |
1031 | ||
1032 | if (daemon_smtp_port[0] <= 0) | |
1033 | log_write(0, LOG_MAIN|LOG_PANIC_DIE, "no port specified for interface " | |
1034 | "%s and daemon_smtp_port is unset; cannot start daemon", | |
1035 | (ipa->address[0] == 0)? US"\"all IPv4\"" : | |
1036 | (ipa->address[1] == 0)? US"\"all IPv6\"" : ipa->address); | |
1037 | ipa->port = default_smtp_port[0]; | |
1038 | for (i = 1; default_smtp_port[i] > 0; i++) | |
1039 | { | |
1040 | ip_address_item *new = store_get(sizeof(ip_address_item)); | |
1041 | memcpy(new->address, ipa->address, Ustrlen(ipa->address) + 1); | |
1042 | new->port = default_smtp_port[i]; | |
1043 | new->next = ipa->next; | |
1044 | ipa->next = new; | |
1045 | ipa = new; | |
1046 | } | |
1047 | } | |
1048 | ||
1049 | /* Scan the list of addresses for wildcards. If we find an IPv4 and an IPv6 | |
1050 | wildcard for the same port, ensure that (a) they are together and (b) the | |
1051 | IPv6 address comes first. This makes handling the messy features easier, and | |
1052 | also simplifies the construction of the "daemon started" log line. */ | |
1053 | ||
1054 | pipa = &addresses; | |
1055 | for (ipa = addresses; ipa != NULL; pipa = &(ipa->next), ipa = ipa->next) | |
1056 | { | |
1057 | ip_address_item *ipa2; | |
1058 | ||
1059 | /* Handle an IPv4 wildcard */ | |
1060 | ||
1061 | if (ipa->address[0] == 0) | |
1062 | { | |
1063 | for (ipa2 = ipa; ipa2->next != NULL; ipa2 = ipa2->next) | |
1064 | { | |
1065 | ip_address_item *ipa3 = ipa2->next; | |
1066 | if (ipa3->address[0] == ':' && | |
1067 | ipa3->address[1] == 0 && | |
1068 | ipa3->port == ipa->port) | |
1069 | { | |
1070 | ipa2->next = ipa3->next; | |
1071 | ipa3->next = ipa; | |
1072 | *pipa = ipa3; | |
1073 | break; | |
1074 | } | |
1075 | } | |
1076 | } | |
1077 | ||
1078 | /* Handle an IPv6 wildcard. */ | |
1079 | ||
1080 | else if (ipa->address[0] == ':' && ipa->address[1] == 0) | |
1081 | { | |
1082 | for (ipa2 = ipa; ipa2->next != NULL; ipa2 = ipa2->next) | |
1083 | { | |
1084 | ip_address_item *ipa3 = ipa2->next; | |
1085 | if (ipa3->address[0] == 0 && ipa3->port == ipa->port) | |
1086 | { | |
1087 | ipa2->next = ipa3->next; | |
1088 | ipa3->next = ipa->next; | |
1089 | ipa->next = ipa3; | |
1090 | ipa = ipa3; | |
1091 | break; | |
1092 | } | |
1093 | } | |
1094 | } | |
1095 | } | |
1096 | ||
1097 | /* Get a vector to remember all the sockets in */ | |
1098 | ||
1099 | for (ipa = addresses; ipa != NULL; ipa = ipa->next) | |
1100 | listen_socket_count++; | |
1101 | listen_sockets = store_get(sizeof(int *) * listen_socket_count); | |
1102 | ||
1103 | /* Do a sanity check on the max connects value just to save us from getting | |
1104 | a huge amount of store. */ | |
1105 | ||
1106 | if (smtp_accept_max > 4095) smtp_accept_max = 4096; | |
1107 | ||
1108 | /* There's no point setting smtp_accept_queue unless it is less than the max | |
1109 | connects limit. The configuration reader ensures that the max is set if the | |
1110 | queue-only option is set. */ | |
1111 | ||
1112 | if (smtp_accept_queue > smtp_accept_max) smtp_accept_queue = 0; | |
1113 | ||
1114 | /* Get somewhere to keep the list of SMTP accepting pids if we are keeping | |
1115 | track of them for total number and queue/host limits. */ | |
1116 | ||
1117 | if (smtp_accept_max > 0) | |
1118 | { | |
1119 | int i; | |
1120 | smtp_slots = store_get(smtp_accept_max * sizeof(smtp_slot)); | |
1121 | for (i = 0; i < smtp_accept_max; i++) smtp_slots[i] = empty_smtp_slot; | |
1122 | } | |
1123 | } | |
1124 | ||
1125 | /* We now close all open file descriptors that we know about, and disconnect | |
1126 | from the controlling terminal, unless background_daemon is unset. This is | |
1127 | always unset when debugging, but can also be forced. Most modern Unixes seem to | |
1128 | have setsid() for getting rid of the controlling terminal. For any OS that | |
1129 | doesn't, setsid() can be #defined as a no-op, or as something else. */ | |
1130 | ||
1131 | if (background_daemon) | |
1132 | { | |
1133 | log_close_all(); /* Just in case anything was logged earlier */ | |
1134 | search_tidyup(); /* Just in case any were used in reading the config. */ | |
1135 | close(0); /* Get rid of stdin/stdout/stderr */ | |
1136 | close(1); | |
1137 | close(2); | |
1138 | log_stderr = NULL; /* So no attempt to copy paniclog output */ | |
1139 | ||
1140 | /* If the parent process of this one has pid == 1, we are re-initializing the | |
1141 | daemon as the result of a SIGHUP. In this case, there is no need to do any | |
1142 | forking, because the controlling terminal has long gone. Otherwise, fork, | |
1143 | in case current process is a process group leader (see 'man setsid' for an | |
1144 | explanation). */ | |
1145 | ||
1146 | if (getppid() != 1) | |
1147 | { | |
1148 | pid_t pid = fork(); | |
1149 | if (pid < 0) log_write(0, LOG_MAIN|LOG_PANIC_DIE, | |
1150 | "fork() failed when starting daemon: %s", strerror(errno)); | |
1151 | if (pid > 0) exit(EXIT_SUCCESS); /* in parent process, just exit */ | |
1152 | (void)setsid(); /* release controlling terminal */ | |
1153 | } | |
1154 | } | |
1155 | ||
1156 | /* We are now in the disconnected, daemon process (unless debugging). Set up | |
1157 | the listening sockets if required. */ | |
1158 | ||
1159 | if (daemon_listen) | |
1160 | { | |
1161 | int sk; | |
1162 | int on = 1; | |
1163 | ip_address_item *ipa; | |
1164 | ||
1165 | /* For each IP address, create a socket, bind it to the appropriate port, and | |
1166 | start listening. See comments above about IPv6 sockets that may or may not | |
1167 | accept IPv4 calls when listening on all interfaces. We also have to cope with | |
1168 | the case of a system with IPv6 libraries, but no IPv6 support in the kernel. | |
1169 | listening, provided a wildcard IPv4 socket for the same port follows. */ | |
1170 | ||
1171 | for (ipa = addresses, sk = 0; sk < listen_socket_count; ipa = ipa->next, sk++) | |
1172 | { | |
1173 | BOOL wildcard; | |
1174 | ip_address_item *ipa2; | |
1175 | int retries = 9; | |
1176 | int af; | |
1177 | ||
1178 | if (Ustrchr(ipa->address, ':') != NULL) | |
1179 | { | |
1180 | af = AF_INET6; | |
1181 | wildcard = ipa->address[1] == 0; | |
1182 | } | |
1183 | else | |
1184 | { | |
1185 | af = AF_INET; | |
1186 | wildcard = ipa->address[0] == 0; | |
1187 | } | |
1188 | ||
1189 | listen_sockets[sk] = ip_socket(SOCK_STREAM, af); | |
1190 | if (listen_sockets[sk] < 0) | |
1191 | { | |
1192 | if (check_special_case(0, addresses, ipa, FALSE)) | |
1193 | { | |
1194 | log_write(0, LOG_MAIN, "Failed to create IPv6 socket for wildcard " | |
1195 | "listening (%s): will use IPv4", strerror(errno)); | |
1196 | goto SKIP_SOCKET; | |
1197 | } | |
1198 | log_write(0, LOG_PANIC_DIE, "IPv%c socket creation failed: %s", | |
1199 | (af == AF_INET6)? '6' : '4', strerror(errno)); | |
1200 | } | |
1201 | ||
1202 | /* If this is an IPv6 wildcard socket, set IPV6_V6ONLY if that option is | |
1203 | available. Just log failure (can get protocol not available, just like | |
1204 | socket creation can). */ | |
1205 | ||
1206 | #ifdef IPV6_V6ONLY | |
1207 | if (af == AF_INET6 && wildcard && | |
1208 | setsockopt(listen_sockets[sk], IPPROTO_IPV6, IPV6_V6ONLY, (char *)(&on), | |
1209 | sizeof(on)) < 0) | |
1210 | log_write(0, LOG_MAIN, "Setting IPV6_V6ONLY on daemon's IPv6 wildcard " | |
1211 | "socket failed (%s): carrying on without it", strerror(errno)); | |
1212 | #endif /* IPV6_V6ONLY */ | |
1213 | ||
1214 | /* Set SO_REUSEADDR so that the daemon can be restarted while a connection | |
1215 | is being handled. Without this, a connection will prevent reuse of the | |
1216 | smtp port for listening. */ | |
1217 | ||
1218 | if (setsockopt(listen_sockets[sk], SOL_SOCKET, SO_REUSEADDR, | |
1219 | (uschar *)(&on), sizeof(on)) < 0) | |
1220 | log_write(0, LOG_MAIN|LOG_PANIC_DIE, "setting SO_REUSEADDR on socket " | |
1221 | "failed when starting daemon: %s", strerror(errno)); | |
1222 | ||
1223 | /* Set TCP_NODELAY; Exim does its own buffering. There is a switch to | |
1224 | disable this because it breaks some broken clients. */ | |
1225 | ||
1226 | if (tcp_nodelay) setsockopt(listen_sockets[sk], IPPROTO_TCP, TCP_NODELAY, | |
1227 | (uschar *)(&on), sizeof(on)); | |
1228 | ||
1229 | /* Now bind the socket to the required port; if Exim is being restarted | |
1230 | it may not always be possible to bind immediately, even with SO_REUSEADDR | |
1231 | set, so try 10 times, waiting between each try. After 10 failures, we give | |
1232 | up. In an IPv6 environment, if bind () fails with the error EADDRINUSE and | |
1233 | we are doing wildcard IPv4 listening and there was a previous IPv6 wildcard | |
1234 | address for the same port, ignore the error on the grounds that we must be | |
1235 | in a system where the IPv6 socket accepts both kinds of call. This is | |
1236 | necessary for (some release of) USAGI Linux; other IP stacks fail at the | |
1237 | listen() stage instead. */ | |
1238 | ||
1239 | for(;;) | |
1240 | { | |
1241 | uschar *msg, *addr; | |
1242 | if (ip_bind(listen_sockets[sk], af, ipa->address, ipa->port) >= 0) break; | |
1243 | if (check_special_case(errno, addresses, ipa, TRUE)) | |
1244 | { | |
1245 | DEBUG(D_any) debug_printf("wildcard IPv4 bind() failed after IPv6 " | |
1246 | "listen() success; EADDRINUSE ignored\n"); | |
1247 | close(listen_sockets[sk]); | |
1248 | goto SKIP_SOCKET; | |
1249 | } | |
1250 | msg = US strerror(errno); | |
1251 | addr = wildcard? ((af == AF_INET6)? US"(any IPv6)" : US"(any IPv4)") : | |
1252 | ipa->address; | |
1253 | if (retries-- <= 0) | |
1254 | log_write(0, LOG_MAIN|LOG_PANIC_DIE, | |
1255 | "socket bind() to port %d for address %s failed: %s: " | |
1256 | "daemon abandoned", ipa->port, addr, msg); | |
1257 | log_write(0, LOG_MAIN, "socket bind() to port %d for address %s " | |
1258 | "failed: %s: waiting before trying again", ipa->port, addr, msg); | |
1259 | sleep(30); | |
1260 | } | |
1261 | ||
1262 | DEBUG(D_any) | |
1263 | { | |
1264 | if (wildcard) | |
1265 | debug_printf("listening on all interfaces (IPv%c) port %d\n", | |
1266 | (af == AF_INET6)? '6' : '4', ipa->port); | |
1267 | else | |
1268 | debug_printf("listening on %s port %d\n", ipa->address, ipa->port); | |
1269 | } | |
1270 | ||
1271 | /* Start listening on the bound socket, establishing the maximum backlog of | |
1272 | connections that is allowed. On success, continue to the next address. */ | |
1273 | ||
1274 | if (listen(listen_sockets[sk], smtp_connect_backlog) >= 0) continue; | |
1275 | ||
1276 | /* Listening has failed. In an IPv6 environment, as for bind(), if listen() | |
1277 | fails with the error EADDRINUSE and we are doing IPv4 wildcard listening | |
1278 | and there was a previous successful IPv6 wildcard listen on the same port, | |
1279 | we want to ignore the error on the grounds that we must be in a system | |
1280 | where the IPv6 socket accepts both kinds of call. */ | |
1281 | ||
1282 | if (!check_special_case(errno, addresses, ipa, TRUE)) | |
1283 | log_write(0, LOG_PANIC_DIE, "listen() failed on interface %s: %s", | |
1284 | wildcard? ((af == AF_INET6)? US"(any IPv6)" : US"(any IPv4)") : | |
1285 | ipa->address, | |
1286 | strerror(errno)); | |
1287 | ||
1288 | DEBUG(D_any) debug_printf("wildcard IPv4 listen() failed after IPv6 " | |
1289 | "listen() success; EADDRINUSE ignored\n"); | |
1290 | close(listen_sockets[sk]); | |
1291 | ||
1292 | /* Come here if there has been a problem with the socket which we | |
1293 | are going to ignore. We remove the address from the chain, and back up the | |
1294 | counts. */ | |
1295 | ||
1296 | SKIP_SOCKET: | |
1297 | sk--; /* Back up the count */ | |
1298 | listen_socket_count--; /* Reduce the total */ | |
1299 | if (ipa == addresses) addresses = ipa->next; else | |
1300 | { | |
1301 | for (ipa2 = addresses; ipa2->next != ipa; ipa2 = ipa2->next); | |
1302 | ipa2->next = ipa->next; | |
1303 | ipa = ipa2; | |
1304 | } | |
1305 | } /* End of bind/listen loop for each address */ | |
1306 | } /* End of setup for listening */ | |
1307 | ||
1308 | ||
1309 | /* If we are not listening, we want to write a pid file only if -oP was | |
1310 | explicitly given. */ | |
1311 | ||
1312 | else if (override_pid_file_path == NULL) write_pid = FALSE; | |
1313 | ||
1314 | /* Write the pid to a known file for assistance in identification, if required. | |
1315 | We do this before giving up root privilege, because on some systems it is | |
1316 | necessary to be root in order to write into the pid file directory. There's | |
1317 | nothing to stop multiple daemons running, as long as no more than one listens | |
1318 | on a given TCP/IP port on the same interface(s). However, in these | |
1319 | circumstances it gets far too complicated to mess with pid file names | |
1320 | automatically. Consequently, Exim 4 writes a pid file only | |
1321 | ||
1322 | (a) When running in the test harness, or | |
1323 | (b) When -bd is used and -oX is not used, or | |
1324 | (c) When -oP is used to supply a path. | |
1325 | ||
1326 | The variable daemon_write_pid is used to control this. */ | |
1327 | ||
1328 | if (running_in_test_harness || write_pid) | |
1329 | { | |
1330 | FILE *f; | |
1331 | ||
1332 | if (override_pid_file_path != NULL) | |
1333 | pid_file_path = override_pid_file_path; | |
1334 | ||
1335 | if (pid_file_path[0] == 0) | |
1336 | pid_file_path = string_sprintf("%s/exim-daemon.pid", spool_directory); | |
1337 | ||
1338 | f = Ufopen(pid_file_path, "wb"); | |
1339 | if (f != NULL) | |
1340 | { | |
1341 | fprintf(f, "%d\n", (int)getpid()); | |
1342 | fchmod(fileno(f), 0644); | |
1343 | fclose(f); | |
1344 | DEBUG(D_any) debug_printf("pid written to %s\n", pid_file_path); | |
1345 | } | |
1346 | else | |
1347 | { | |
1348 | DEBUG(D_any) | |
1349 | debug_printf("%s\n", string_open_failed(errno, "pid file %s", | |
1350 | pid_file_path)); | |
1351 | } | |
1352 | } | |
1353 | ||
1354 | /* Set up the handler for SIGHUP, which causes a restart of the daemon. */ | |
1355 | ||
1356 | sighup_seen = FALSE; | |
1357 | signal(SIGHUP, sighup_handler); | |
1358 | ||
1359 | /* Give up root privilege at this point (assuming that exim_uid and exim_gid | |
1360 | are not root). The third argument controls the running of initgroups(). | |
1361 | Normally we do this, in order to set up the groups for the Exim user. However, | |
1362 | if we are not root at this time - some odd installations run that way - we | |
1363 | cannot do this. */ | |
1364 | ||
1365 | exim_setugid(exim_uid, exim_gid, geteuid()==root_uid, US"running as a daemon"); | |
1366 | ||
1367 | /* Get somewhere to keep the list of queue-runner pids if we are keeping track | |
1368 | of them (and also if we are doing queue runs). */ | |
1369 | ||
1370 | if (queue_interval > 0 && queue_run_max > 0) | |
1371 | { | |
1372 | int i; | |
1373 | queue_pid_slots = store_get(queue_run_max * sizeof(pid_t)); | |
1374 | for (i = 0; i < queue_run_max; i++) queue_pid_slots[i] = 0; | |
1375 | } | |
1376 | ||
1377 | /* Set up the handler for termination of child processes. */ | |
1378 | ||
1379 | sigchld_seen = FALSE; | |
7d468ab8 | 1380 | os_non_restarting_signal(SIGCHLD, main_sigchld_handler); |
059ec3d9 PH |
1381 | |
1382 | /* If we are to run the queue periodically, pretend the alarm has just gone | |
1383 | off. This will cause the first queue-runner to get kicked off straight away. */ | |
1384 | ||
1385 | sigalrm_seen = (queue_interval > 0); | |
1386 | ||
1387 | /* Log the start up of a daemon - at least one of listening or queue running | |
1388 | must be set up. */ | |
1389 | ||
1390 | if (daemon_listen) | |
1391 | { | |
1392 | int i, j; | |
1393 | int smtp_ports = 0; | |
1394 | int smtps_ports = 0; | |
1395 | ip_address_item *ipa; | |
1396 | uschar *p = big_buffer; | |
1397 | uschar *qinfo = (queue_interval > 0)? | |
1398 | string_sprintf("-q%s", readconf_printtime(queue_interval)) | |
1399 | : | |
1400 | US"no queue runs"; | |
1401 | ||
1402 | /* Build a list of listening addresses in big_buffer, but limit it to 10 | |
1403 | items. The style is for backwards compatibility. | |
1404 | ||
1405 | It is now possible to have some ports listening for SMTPS (the old, | |
1406 | deprecated protocol that starts TLS without using STARTTLS), and others | |
1407 | listening for standard SMTP. Keep their listings separate. */ | |
1408 | ||
1409 | for (j = 0; j < 2; j++) | |
1410 | { | |
1411 | for (i = 0, ipa = addresses; i < 10 && ipa != NULL; i++, ipa = ipa->next) | |
1412 | { | |
1413 | /* First time round, look for SMTP ports; second time round, look for | |
1414 | SMTPS ports. For the first one of each, insert leading text. */ | |
1415 | ||
1416 | if (host_is_tls_on_connect_port(ipa->port) == (j > 0)) | |
1417 | { | |
1418 | if (j == 0) | |
1419 | { | |
1420 | if (smtp_ports++ == 0) | |
1421 | { | |
1422 | memcpy(p, "SMTP on", 8); | |
1423 | p += 7; | |
1424 | } | |
1425 | } | |
1426 | else | |
1427 | { | |
1428 | if (smtps_ports++ == 0) | |
1429 | { | |
1430 | (void)sprintf(CS p, "%sSMTPS on", | |
1431 | (smtp_ports == 0)? "":" and for "); | |
1432 | while (*p != 0) p++; | |
1433 | } | |
1434 | } | |
1435 | ||
1436 | /* Now the information about the port (and sometimes interface) */ | |
1437 | ||
1438 | if (ipa->address[0] == ':' && ipa->address[1] == 0) | |
1439 | { | |
1440 | if (ipa->next != NULL && ipa->next->address[0] == 0 && | |
1441 | ipa->next->port == ipa->port) | |
1442 | { | |
1443 | (void)sprintf(CS p, " port %d (IPv6 and IPv4)", ipa->port); | |
1444 | ipa = ipa->next; | |
1445 | } | |
1446 | else if (ipa->v6_include_v4) | |
1447 | (void)sprintf(CS p, " port %d (IPv6 with IPv4)", ipa->port); | |
1448 | else | |
1449 | (void)sprintf(CS p, " port %d (IPv6)", ipa->port); | |
1450 | } | |
1451 | else if (ipa->address[0] == 0) | |
1452 | (void)sprintf(CS p, " port %d (IPv4)", ipa->port); | |
1453 | else | |
1454 | (void)sprintf(CS p, " [%s]:%d", ipa->address, ipa->port); | |
1455 | while (*p != 0) p++; | |
1456 | } | |
1457 | } | |
1458 | ||
1459 | if (ipa != NULL) | |
1460 | { | |
1461 | memcpy(p, " ...", 5); | |
1462 | p += 4; | |
1463 | } | |
1464 | } | |
1465 | ||
1466 | log_write(0, LOG_MAIN, | |
1467 | "exim %s daemon started: pid=%d, %s, listening for %s", | |
1468 | version_string, getpid(), qinfo, big_buffer); | |
1469 | set_process_info("daemon: %s, listening for %s", qinfo, big_buffer); | |
1470 | } | |
1471 | ||
1472 | else | |
1473 | { | |
1474 | log_write(0, LOG_MAIN, | |
1475 | "exim %s daemon started: pid=%d, -q%s, not listening for SMTP", | |
1476 | version_string, getpid(), readconf_printtime(queue_interval)); | |
1477 | set_process_info("daemon: -q%s, not listening", | |
1478 | readconf_printtime(queue_interval)); | |
1479 | } | |
1480 | ||
1481 | ||
1482 | /* Close the log so it can be renamed and moved. In the few cases below where | |
1483 | this long-running process writes to the log (always exceptional conditions), it | |
1484 | closes the log afterwards, for the same reason. */ | |
1485 | ||
1486 | log_close_all(); | |
1487 | ||
1488 | DEBUG(D_any) debug_print_ids(US"daemon running with"); | |
1489 | ||
1490 | /* Any messages accepted via this route are going to be SMTP. */ | |
1491 | ||
1492 | smtp_input = TRUE; | |
1493 | ||
1494 | /* Enter the never-ending loop... */ | |
1495 | ||
1496 | for (;;) | |
1497 | { | |
1498 | #if HAVE_IPV6 | |
1499 | struct sockaddr_in6 accepted; | |
1500 | #else | |
1501 | struct sockaddr_in accepted; | |
1502 | #endif | |
1503 | ||
1504 | SOCKLEN_T len = sizeof(accepted); | |
1505 | int status; | |
1506 | pid_t pid; | |
1507 | ||
1508 | /* This code is placed first in the loop, so that it gets obeyed at the | |
1509 | start, before the first wait. This causes the first queue-runner to be | |
1510 | started immediately. */ | |
1511 | ||
1512 | if (sigalrm_seen) | |
1513 | { | |
1514 | DEBUG(D_any) debug_printf("SIGALRM received\n"); | |
1515 | ||
1516 | /* Do a full queue run in a child process, if required, unless we already | |
1517 | have enough queue runners on the go. If we are not running as root, a | |
1518 | re-exec is required. */ | |
1519 | ||
1520 | if (queue_interval > 0 && | |
1521 | (queue_run_max <= 0 || queue_run_count < queue_run_max)) | |
1522 | { | |
1523 | if ((pid = fork()) == 0) | |
1524 | { | |
1525 | int sk; | |
3d235903 | 1526 | |
059ec3d9 PH |
1527 | DEBUG(D_any) debug_printf("Starting queue-runner: pid %d\n", |
1528 | (int)getpid()); | |
1529 | ||
3d235903 PH |
1530 | /* Disable debugging if it's required only for the daemon process. We |
1531 | leave the above message, because it ties up with the "child ended" | |
1532 | debugging messages. */ | |
1533 | ||
1534 | if (debug_daemon) debug_selector = 0; | |
1535 | ||
059ec3d9 PH |
1536 | /* Close any open listening sockets in the child */ |
1537 | ||
1538 | for (sk = 0; sk < listen_socket_count; sk++) close(listen_sockets[sk]); | |
1539 | ||
1540 | /* Reset SIGHUP and SIGCHLD in the child in both cases. */ | |
1541 | ||
1542 | signal(SIGHUP, SIG_DFL); | |
1543 | signal(SIGCHLD, SIG_DFL); | |
1544 | ||
1545 | /* Re-exec if privilege has been given up, unless deliver_drop_ | |
1546 | privilege is set. Reset SIGALRM before exec(). */ | |
1547 | ||
1548 | if (geteuid() != root_uid && !deliver_drop_privilege) | |
1549 | { | |
1550 | uschar opt[8]; | |
1551 | uschar *p = opt; | |
1552 | ||
1553 | signal(SIGALRM, SIG_DFL); | |
1554 | *p++ = '-'; | |
1555 | *p++ = 'q'; | |
1556 | if (queue_2stage) *p++ = 'q'; | |
1557 | if (queue_run_first_delivery) *p++ = 'i'; | |
1558 | if (queue_run_force) *p++ = 'f'; | |
1559 | if (deliver_force_thaw) *p++ = 'f'; | |
1560 | if (queue_run_local) *p++ = 'l'; | |
1561 | *p = 0; | |
1562 | ||
1563 | (void)child_exec_exim(CEE_EXEC_PANIC, FALSE, NULL, TRUE, 1, opt); | |
1564 | /* Control never returns here. */ | |
1565 | } | |
1566 | ||
1567 | /* No need to re-exec; SIGALRM remains set to the default handler */ | |
1568 | ||
1569 | queue_run(NULL, NULL, FALSE); | |
1570 | _exit(EXIT_SUCCESS); | |
1571 | } | |
1572 | ||
1573 | if (pid < 0) | |
1574 | { | |
1575 | log_write(0, LOG_MAIN|LOG_PANIC, "daemon: fork of queue-runner " | |
1576 | "process failed: %s", strerror(errno)); | |
1577 | log_close_all(); | |
1578 | } | |
1579 | else | |
1580 | { | |
1581 | int i; | |
1582 | for (i = 0; i < queue_run_max; ++i) | |
1583 | { | |
1584 | if (queue_pid_slots[i] <= 0) | |
1585 | { | |
1586 | queue_pid_slots[i] = pid; | |
1587 | queue_run_count++; | |
1588 | break; | |
1589 | } | |
1590 | } | |
1591 | DEBUG(D_any) debug_printf("%d queue-runner process%s running\n", | |
1592 | queue_run_count, (queue_run_count == 1)? "" : "es"); | |
1593 | } | |
1594 | } | |
1595 | ||
1596 | /* Reset the alarm clock */ | |
1597 | ||
1598 | sigalrm_seen = FALSE; | |
1599 | alarm(queue_interval); | |
1600 | } | |
1601 | ||
1602 | ||
1603 | /* Sleep till a connection happens if listening, and handle the connection if | |
1604 | that is why we woke up. The FreeBSD operating system requires the use of | |
1605 | select() before accept() because the latter function is not interrupted by | |
1606 | a signal, and we want to wake up for SIGCHLD and SIGALRM signals. Some other | |
1607 | OS do notice signals in accept() but it does no harm to have the select() | |
1608 | in for all of them - and it won't then be a lurking problem for ports to | |
1609 | new OS. In fact, the later addition of listening on specific interfaces only | |
1610 | requires this way of working anyway. */ | |
1611 | ||
1612 | if (daemon_listen) | |
1613 | { | |
1614 | int sk, lcount; | |
1615 | int max_socket = 0; | |
1616 | BOOL select_failed = FALSE; | |
1617 | fd_set select_listen; | |
1618 | ||
1619 | FD_ZERO(&select_listen); | |
1620 | for (sk = 0; sk < listen_socket_count; sk++) | |
1621 | { | |
1622 | FD_SET(listen_sockets[sk], &select_listen); | |
1623 | if (listen_sockets[sk] > max_socket) max_socket = listen_sockets[sk]; | |
1624 | } | |
1625 | ||
1626 | DEBUG(D_any) debug_printf("Listening...\n"); | |
7d468ab8 PH |
1627 | |
1628 | /* In rare cases we may have had a SIGCHLD signal in the time between | |
1629 | setting the handler (below) and getting back here. If so, pretend that the | |
1630 | select() was interrupted so that we reap the child. This might still leave | |
1631 | a small window when a SIGCHLD could get lost. However, since we use SIGCHLD | |
1632 | only to do the reaping more quickly, it shouldn't result in anything other | |
1633 | than a delay until something else causes a wake-up. */ | |
1634 | ||
1635 | if (sigchld_seen) | |
1636 | { | |
1637 | lcount = -1; | |
1638 | errno = EINTR; | |
1639 | } | |
1640 | else | |
1641 | { | |
1642 | lcount = select(max_socket + 1, (SELECT_ARG2_TYPE *)&select_listen, | |
1643 | NULL, NULL, NULL); | |
1644 | } | |
059ec3d9 | 1645 | |
7d468ab8 | 1646 | if (lcount < 0) |
059ec3d9 PH |
1647 | { |
1648 | select_failed = TRUE; | |
1649 | lcount = 1; | |
1650 | } | |
7d468ab8 | 1651 | |
059ec3d9 | 1652 | /* Loop for all the sockets that are currently ready to go. If select |
7d468ab8 PH |
1653 | actually failed, we have set the count to 1 and select_failed=TRUE, so as |
1654 | to use the common error code for select/accept below. */ | |
059ec3d9 PH |
1655 | |
1656 | while (lcount-- > 0) | |
1657 | { | |
1658 | int accept_socket = -1; | |
1659 | if (!select_failed) | |
1660 | { | |
1661 | for (sk = 0; sk < listen_socket_count; sk++) | |
1662 | { | |
1663 | if (FD_ISSET(listen_sockets[sk], &select_listen)) | |
1664 | { | |
1665 | accept_socket = accept(listen_sockets[sk], | |
1666 | (struct sockaddr *)&accepted, &len); | |
1667 | FD_CLR(listen_sockets[sk], &select_listen); | |
1668 | break; | |
1669 | } | |
1670 | } | |
1671 | } | |
1672 | ||
1673 | /* If select or accept has failed and this was not caused by an | |
1674 | interruption, log the incident and try again. With asymmetric TCP/IP | |
1675 | routing errors such as "No route to network" have been seen here. Also | |
1676 | "connection reset by peer" has been seen. These cannot be classed as | |
1677 | disastrous errors, but they could fill up a lot of log. The code in smail | |
1678 | crashes the daemon after 10 successive failures of accept, on the grounds | |
1679 | that some OS fail continuously. Exim originally followed suit, but this | |
1680 | appears to have caused problems. Now it just keeps going, but instead of | |
1681 | logging each error, it batches them up when they are continuous. */ | |
1682 | ||
1683 | if (accept_socket < 0 && errno != EINTR) | |
1684 | { | |
1685 | if (accept_retry_count == 0) | |
1686 | { | |
1687 | accept_retry_errno = errno; | |
1688 | accept_retry_select_failed = select_failed; | |
1689 | } | |
1690 | else | |
1691 | { | |
1692 | if (errno != accept_retry_errno || | |
1693 | select_failed != accept_retry_select_failed || | |
1694 | accept_retry_count >= 50) | |
1695 | { | |
1696 | log_write(0, LOG_MAIN | ((accept_retry_count >= 50)? LOG_PANIC : 0), | |
1697 | "%d %s() failure%s: %s", | |
1698 | accept_retry_count, | |
1699 | accept_retry_select_failed? "select" : "accept", | |
1700 | (accept_retry_count == 1)? "" : "s", | |
1701 | strerror(accept_retry_errno)); | |
1702 | log_close_all(); | |
1703 | accept_retry_count = 0; | |
1704 | accept_retry_errno = errno; | |
1705 | accept_retry_select_failed = select_failed; | |
1706 | } | |
1707 | } | |
1708 | accept_retry_count++; | |
1709 | } | |
1710 | ||
1711 | else | |
1712 | { | |
1713 | if (accept_retry_count > 0) | |
1714 | { | |
1715 | log_write(0, LOG_MAIN, "%d %s() failure%s: %s", | |
1716 | accept_retry_count, | |
1717 | accept_retry_select_failed? "select" : "accept", | |
1718 | (accept_retry_count == 1)? "" : "s", | |
1719 | strerror(accept_retry_errno)); | |
1720 | log_close_all(); | |
1721 | accept_retry_count = 0; | |
1722 | } | |
1723 | } | |
1724 | ||
1725 | /* If select/accept succeeded, deal with the connection. */ | |
1726 | ||
1727 | if (accept_socket >= 0) | |
1728 | handle_smtp_call(listen_sockets, listen_socket_count, accept_socket, | |
1729 | (struct sockaddr *)&accepted); | |
1730 | } | |
1731 | } | |
1732 | ||
1733 | /* If not listening, then just sleep for the queue interval. If we woke | |
1734 | up early the last time for some other signal, it won't matter because | |
1735 | the alarm signal will wake at the right time. This code originally used | |
1736 | sleep() but it turns out that on the FreeBSD system, sleep() is not inter- | |
1737 | rupted by signals, so it wasn't waking up for SIGALRM or SIGCHLD. Luckily | |
1738 | select() can be used as an interruptible sleep() on all versions of Unix. */ | |
1739 | ||
1740 | else | |
1741 | { | |
1742 | struct timeval tv; | |
1743 | tv.tv_sec = queue_interval; | |
1744 | tv.tv_usec = 0; | |
1745 | select(0, NULL, NULL, NULL, &tv); | |
1746 | } | |
1747 | ||
1748 | /* Handle the termination of a child process. Theoretically, this need | |
1749 | be done only when sigchld_seen is TRUE, but rumour has it that some systems | |
1750 | lose SIGCHLD signals at busy times, so to be on the safe side, just | |
1751 | do it each time round. It shouldn't be too expensive. */ | |
1752 | ||
1753 | while ((pid = waitpid(-1, &status, WNOHANG)) > 0) | |
1754 | { | |
1755 | int i; | |
1756 | DEBUG(D_any) debug_printf("child %d ended: status=0x%x\n", (int)pid, | |
1757 | status); | |
1758 | ||
1759 | /* If it's a listening daemon, deal with an accepting process that has | |
1760 | terminated. */ | |
1761 | ||
1762 | if (daemon_listen) | |
1763 | { | |
1764 | for (i = 0; i < smtp_accept_max; i++) | |
1765 | { | |
1766 | if (smtp_slots[i].pid == pid) | |
1767 | { | |
1768 | if (smtp_slots[i].host_address != NULL) | |
1769 | store_free(smtp_slots[i].host_address); | |
1770 | smtp_slots[i] = empty_smtp_slot; | |
1771 | if (--smtp_accept_count < 0) smtp_accept_count = 0; | |
1772 | DEBUG(D_any) debug_printf("%d SMTP accept process%s now running\n", | |
1773 | smtp_accept_count, (smtp_accept_count == 1)? "" : "es"); | |
1774 | break; | |
1775 | } | |
1776 | } | |
1777 | if (i < smtp_accept_max) continue; /* Found an accepting process */ | |
1778 | } | |
1779 | ||
1780 | /* If it wasn't an accepting process, see if it was a queue-runner | |
1781 | process, if we are keeping track of them. */ | |
1782 | ||
1783 | if (queue_interval > 0) | |
1784 | { | |
1785 | for (i = 0; i < queue_run_max; i++) | |
1786 | { | |
1787 | if (queue_pid_slots[i] == pid) | |
1788 | { | |
1789 | queue_pid_slots[i] = 0; | |
1790 | if (--queue_run_count < 0) queue_run_count = 0; | |
1791 | DEBUG(D_any) debug_printf("%d queue-runner process%s now running\n", | |
1792 | queue_run_count, (queue_run_count == 1)? "" : "es"); | |
1793 | break; | |
1794 | } | |
1795 | } | |
1796 | } | |
1797 | } | |
1798 | ||
1799 | /* Re-enable the SIGCHLD handler if it has been run. It can't do it | |
1800 | for itself, because it isn't doing the waiting itself. */ | |
1801 | ||
1802 | if (sigchld_seen) | |
1803 | { | |
1804 | sigchld_seen = FALSE; | |
7d468ab8 | 1805 | os_non_restarting_signal(SIGCHLD, main_sigchld_handler); |
059ec3d9 PH |
1806 | } |
1807 | ||
1808 | /* Handle being woken by SIGHUP. We know at this point that the result | |
1809 | of accept() has been dealt with, so we can re-exec exim safely, first | |
1810 | closing the listening sockets so that they can be reused. Cancel any pending | |
1811 | alarm in case it is just about to go off, and set SIGHUP to be ignored so | |
1812 | that another HUP in quick succession doesn't clobber the new daemon before it | |
1813 | gets going. All log files get closed by the close-on-exec flag; however, if | |
1814 | the exec fails, we need to close the logs. */ | |
1815 | ||
1816 | if (sighup_seen) | |
1817 | { | |
1818 | int sk; | |
1819 | log_write(0, LOG_MAIN, "pid %d: SIGHUP received: re-exec daemon", | |
1820 | getpid()); | |
1821 | for (sk = 0; sk < listen_socket_count; sk++) close(listen_sockets[sk]); | |
1822 | alarm(0); | |
1823 | signal(SIGHUP, SIG_IGN); | |
1824 | sighup_argv[0] = exim_path; | |
1825 | exim_nullstd(); | |
1826 | execv(CS exim_path, (char *const *)sighup_argv); | |
1827 | log_write(0, LOG_MAIN|LOG_PANIC_DIE, "pid %d: exec of %s failed: %s", | |
1828 | getpid(), exim_path, strerror(errno)); | |
1829 | log_close_all(); | |
1830 | } | |
1831 | ||
1832 | } /* End of main loop */ | |
1833 | ||
1834 | /* Control never reaches here */ | |
1835 | } | |
1836 | ||
1837 | /* End of exim_daemon.c */ | |
1838 |