| 1 | /************************************************* |
| 2 | * Exim - an Internet mail transport agent * |
| 3 | *************************************************/ |
| 4 | |
| 5 | /* Copyright (c) University of Cambridge 1995 - 2018 */ |
| 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 | |
| 16 | typedef 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 |
| 22 | expressions in assignments except as initializers in declarations). */ |
| 23 | |
| 24 | static smtp_slot empty_smtp_slot = { .pid = 0, .host_address = NULL }; |
| 25 | |
| 26 | |
| 27 | |
| 28 | /************************************************* |
| 29 | * Local static variables * |
| 30 | *************************************************/ |
| 31 | |
| 32 | static SIGNAL_BOOL sigchld_seen; |
| 33 | static SIGNAL_BOOL sighup_seen; |
| 34 | static SIGNAL_BOOL sigterm_seen; |
| 35 | |
| 36 | static int accept_retry_count = 0; |
| 37 | static int accept_retry_errno; |
| 38 | static BOOL accept_retry_select_failed; |
| 39 | |
| 40 | static int queue_run_count = 0; |
| 41 | static pid_t *queue_pid_slots = NULL; |
| 42 | static smtp_slot *smtp_slots = NULL; |
| 43 | |
| 44 | static BOOL write_pid = TRUE; |
| 45 | |
| 46 | |
| 47 | |
| 48 | /************************************************* |
| 49 | * SIGHUP Handler * |
| 50 | *************************************************/ |
| 51 | |
| 52 | /* All this handler does is to set a flag and re-enable the signal. |
| 53 | |
| 54 | Argument: the signal number |
| 55 | Returns: nothing |
| 56 | */ |
| 57 | |
| 58 | static void |
| 59 | sighup_handler(int sig) |
| 60 | { |
| 61 | sig = sig; /* Keep picky compilers happy */ |
| 62 | sighup_seen = TRUE; |
| 63 | signal(SIGHUP, sighup_handler); |
| 64 | } |
| 65 | |
| 66 | |
| 67 | |
| 68 | /************************************************* |
| 69 | * SIGCHLD handler for main daemon process * |
| 70 | *************************************************/ |
| 71 | |
| 72 | /* Don't re-enable the handler here, since we aren't doing the |
| 73 | waiting here. If the signal is re-enabled, there will just be an |
| 74 | infinite sequence of calls to this handler. The SIGCHLD signal is |
| 75 | used just as a means of waking up the daemon so that it notices |
| 76 | terminated subprocesses as soon as possible. |
| 77 | |
| 78 | Argument: the signal number |
| 79 | Returns: nothing |
| 80 | */ |
| 81 | |
| 82 | static void |
| 83 | main_sigchld_handler(int sig) |
| 84 | { |
| 85 | sig = sig; /* Keep picky compilers happy */ |
| 86 | os_non_restarting_signal(SIGCHLD, SIG_DFL); |
| 87 | sigchld_seen = TRUE; |
| 88 | } |
| 89 | |
| 90 | |
| 91 | /* SIGTERM handler. Try to get the damon pif file removed |
| 92 | before exiting. */ |
| 93 | |
| 94 | static void |
| 95 | main_sigterm_handler(int sig) |
| 96 | { |
| 97 | sigterm_seen = TRUE; |
| 98 | } |
| 99 | |
| 100 | |
| 101 | |
| 102 | |
| 103 | /************************************************* |
| 104 | * Unexpected errors in SMTP calls * |
| 105 | *************************************************/ |
| 106 | |
| 107 | /* This function just saves a bit of repetitious coding. |
| 108 | |
| 109 | Arguments: |
| 110 | log_msg Text of message to be logged |
| 111 | smtp_msg Text of SMTP error message |
| 112 | was_errno The failing errno |
| 113 | |
| 114 | Returns: nothing |
| 115 | */ |
| 116 | |
| 117 | static void |
| 118 | never_error(uschar *log_msg, uschar *smtp_msg, int was_errno) |
| 119 | { |
| 120 | uschar *emsg = was_errno <= 0 |
| 121 | ? US"" : string_sprintf(": %s", strerror(was_errno)); |
| 122 | log_write(0, LOG_MAIN|LOG_PANIC, "%s%s", log_msg, emsg); |
| 123 | if (smtp_out) smtp_printf("421 %s\r\n", FALSE, smtp_msg); |
| 124 | } |
| 125 | |
| 126 | |
| 127 | |
| 128 | |
| 129 | /************************************************* |
| 130 | * Handle a connected SMTP call * |
| 131 | *************************************************/ |
| 132 | |
| 133 | /* This function is called when an SMTP connection has been accepted. |
| 134 | If there are too many, give an error message and close down. Otherwise |
| 135 | spin off a sub-process to handle the call. The list of listening sockets |
| 136 | is required so that they can be closed in the sub-process. Take care not to |
| 137 | leak store in this process - reset the stacking pool at the end. |
| 138 | |
| 139 | Arguments: |
| 140 | listen_sockets sockets which are listening for incoming calls |
| 141 | listen_socket_count count of listening sockets |
| 142 | accept_socket socket of the current accepted call |
| 143 | accepted socket information about the current call |
| 144 | |
| 145 | Returns: nothing |
| 146 | */ |
| 147 | |
| 148 | static void |
| 149 | handle_smtp_call(int *listen_sockets, int listen_socket_count, |
| 150 | int accept_socket, struct sockaddr *accepted) |
| 151 | { |
| 152 | pid_t pid; |
| 153 | union sockaddr_46 interface_sockaddr; |
| 154 | EXIM_SOCKLEN_T ifsize = sizeof(interface_sockaddr); |
| 155 | int dup_accept_socket = -1; |
| 156 | int max_for_this_host = 0; |
| 157 | int save_log_selector = *log_selector; |
| 158 | gstring * whofrom; |
| 159 | |
| 160 | rmark reset_point = store_mark(); |
| 161 | |
| 162 | /* Make the address available in ASCII representation, and also fish out |
| 163 | the remote port. */ |
| 164 | |
| 165 | sender_host_address = host_ntoa(-1, accepted, NULL, &sender_host_port); |
| 166 | DEBUG(D_any) debug_printf("Connection request from %s port %d\n", |
| 167 | sender_host_address, sender_host_port); |
| 168 | |
| 169 | /* Set up the output stream, check the socket has duplicated, and set up the |
| 170 | input stream. These operations fail only the exceptional circumstances. Note |
| 171 | that never_error() won't use smtp_out if it is NULL. */ |
| 172 | |
| 173 | if (!(smtp_out = fdopen(accept_socket, "wb"))) |
| 174 | { |
| 175 | never_error(US"daemon: fdopen() for smtp_out failed", US"", errno); |
| 176 | goto ERROR_RETURN; |
| 177 | } |
| 178 | |
| 179 | if ((dup_accept_socket = dup(accept_socket)) < 0) |
| 180 | { |
| 181 | never_error(US"daemon: couldn't dup socket descriptor", |
| 182 | US"Connection setup failed", errno); |
| 183 | goto ERROR_RETURN; |
| 184 | } |
| 185 | |
| 186 | if (!(smtp_in = fdopen(dup_accept_socket, "rb"))) |
| 187 | { |
| 188 | never_error(US"daemon: fdopen() for smtp_in failed", |
| 189 | US"Connection setup failed", errno); |
| 190 | goto ERROR_RETURN; |
| 191 | } |
| 192 | |
| 193 | /* Get the data for the local interface address. Panic for most errors, but |
| 194 | "connection reset by peer" just means the connection went away. */ |
| 195 | |
| 196 | if (getsockname(accept_socket, (struct sockaddr *)(&interface_sockaddr), |
| 197 | &ifsize) < 0) |
| 198 | { |
| 199 | log_write(0, LOG_MAIN | ((errno == ECONNRESET)? 0 : LOG_PANIC), |
| 200 | "getsockname() failed: %s", strerror(errno)); |
| 201 | smtp_printf("421 Local problem: getsockname() failed; please try again later\r\n", FALSE); |
| 202 | goto ERROR_RETURN; |
| 203 | } |
| 204 | |
| 205 | interface_address = host_ntoa(-1, &interface_sockaddr, NULL, &interface_port); |
| 206 | DEBUG(D_interface) debug_printf("interface address=%s port=%d\n", |
| 207 | interface_address, interface_port); |
| 208 | |
| 209 | /* Build a string identifying the remote host and, if requested, the port and |
| 210 | the local interface data. This is for logging; at the end of this function the |
| 211 | memory is reclaimed. */ |
| 212 | |
| 213 | whofrom = string_append(NULL, 3, "[", sender_host_address, "]"); |
| 214 | |
| 215 | if (LOGGING(incoming_port)) |
| 216 | whofrom = string_fmt_append(whofrom, ":%d", sender_host_port); |
| 217 | |
| 218 | if (LOGGING(incoming_interface)) |
| 219 | whofrom = string_fmt_append(whofrom, " I=[%s]:%d", |
| 220 | interface_address, interface_port); |
| 221 | |
| 222 | (void) string_from_gstring(whofrom); /* Terminate the newly-built string */ |
| 223 | |
| 224 | /* Check maximum number of connections. We do not check for reserved |
| 225 | connections or unacceptable hosts here. That is done in the subprocess because |
| 226 | it might take some time. */ |
| 227 | |
| 228 | if (smtp_accept_max > 0 && smtp_accept_count >= smtp_accept_max) |
| 229 | { |
| 230 | DEBUG(D_any) debug_printf("rejecting SMTP connection: count=%d max=%d\n", |
| 231 | smtp_accept_count, smtp_accept_max); |
| 232 | smtp_printf("421 Too many concurrent SMTP connections; " |
| 233 | "please try again later.\r\n", FALSE); |
| 234 | log_write(L_connection_reject, |
| 235 | LOG_MAIN, "Connection from %s refused: too many connections", |
| 236 | whofrom->s); |
| 237 | goto ERROR_RETURN; |
| 238 | } |
| 239 | |
| 240 | /* If a load limit above which only reserved hosts are acceptable is defined, |
| 241 | get the load average here, and if there are in fact no reserved hosts, do |
| 242 | the test right away (saves a fork). If there are hosts, do the check in the |
| 243 | subprocess because it might take time. */ |
| 244 | |
| 245 | if (smtp_load_reserve >= 0) |
| 246 | { |
| 247 | load_average = OS_GETLOADAVG(); |
| 248 | if (smtp_reserve_hosts == NULL && load_average > smtp_load_reserve) |
| 249 | { |
| 250 | DEBUG(D_any) debug_printf("rejecting SMTP connection: load average = %.2f\n", |
| 251 | (double)load_average/1000.0); |
| 252 | smtp_printf("421 Too much load; please try again later.\r\n", FALSE); |
| 253 | log_write(L_connection_reject, |
| 254 | LOG_MAIN, "Connection from %s refused: load average = %.2f", |
| 255 | whofrom->s, (double)load_average/1000.0); |
| 256 | goto ERROR_RETURN; |
| 257 | } |
| 258 | } |
| 259 | |
| 260 | /* Check that one specific host (strictly, IP address) is not hogging |
| 261 | resources. This is done here to prevent a denial of service attack by someone |
| 262 | forcing you to fork lots of times before denying service. The value of |
| 263 | smtp_accept_max_per_host is a string which is expanded. This makes it possible |
| 264 | to provide host-specific limits according to $sender_host address, but because |
| 265 | this is in the daemon mainline, only fast expansions (such as inline address |
| 266 | checks) should be used. The documentation is full of warnings. */ |
| 267 | |
| 268 | if (smtp_accept_max_per_host != NULL) |
| 269 | { |
| 270 | uschar *expanded = expand_string(smtp_accept_max_per_host); |
| 271 | if (expanded == NULL) |
| 272 | { |
| 273 | if (!f.expand_string_forcedfail) |
| 274 | log_write(0, LOG_MAIN|LOG_PANIC, "expansion of smtp_accept_max_per_host " |
| 275 | "failed for %s: %s", whofrom->s, expand_string_message); |
| 276 | } |
| 277 | /* For speed, interpret a decimal number inline here */ |
| 278 | else |
| 279 | { |
| 280 | uschar *s = expanded; |
| 281 | while (isdigit(*s)) |
| 282 | max_for_this_host = max_for_this_host * 10 + *s++ - '0'; |
| 283 | if (*s != 0) |
| 284 | log_write(0, LOG_MAIN|LOG_PANIC, "expansion of smtp_accept_max_per_host " |
| 285 | "for %s contains non-digit: %s", whofrom->s, expanded); |
| 286 | } |
| 287 | } |
| 288 | |
| 289 | /* If we have fewer connections than max_for_this_host, we can skip the tedious |
| 290 | per host_address checks. Note that at this stage smtp_accept_count contains the |
| 291 | count of *other* connections, not including this one. */ |
| 292 | |
| 293 | if ((max_for_this_host > 0) && |
| 294 | (smtp_accept_count >= max_for_this_host)) |
| 295 | { |
| 296 | int host_accept_count = 0; |
| 297 | int other_host_count = 0; /* keep a count of non matches to optimise */ |
| 298 | |
| 299 | for (int i = 0; i < smtp_accept_max; ++i) |
| 300 | if (smtp_slots[i].host_address) |
| 301 | { |
| 302 | if (Ustrcmp(sender_host_address, smtp_slots[i].host_address) == 0) |
| 303 | host_accept_count++; |
| 304 | else |
| 305 | other_host_count++; |
| 306 | |
| 307 | /* Testing all these strings is expensive - see if we can drop out |
| 308 | early, either by hitting the target, or finding there are not enough |
| 309 | connections left to make the target. */ |
| 310 | |
| 311 | if ((host_accept_count >= max_for_this_host) || |
| 312 | ((smtp_accept_count - other_host_count) < max_for_this_host)) |
| 313 | break; |
| 314 | } |
| 315 | |
| 316 | if (host_accept_count >= max_for_this_host) |
| 317 | { |
| 318 | DEBUG(D_any) debug_printf("rejecting SMTP connection: too many from this " |
| 319 | "IP address: count=%d max=%d\n", |
| 320 | host_accept_count, max_for_this_host); |
| 321 | smtp_printf("421 Too many concurrent SMTP connections " |
| 322 | "from this IP address; please try again later.\r\n", FALSE); |
| 323 | log_write(L_connection_reject, |
| 324 | LOG_MAIN, "Connection from %s refused: too many connections " |
| 325 | "from that IP address", whofrom->s); |
| 326 | goto ERROR_RETURN; |
| 327 | } |
| 328 | } |
| 329 | |
| 330 | /* OK, the connection count checks have been passed. Before we can fork the |
| 331 | accepting process, we must first log the connection if requested. This logging |
| 332 | used to happen in the subprocess, but doing that means that the value of |
| 333 | smtp_accept_count can be out of step by the time it is logged. So we have to do |
| 334 | the logging here and accept the performance cost. Note that smtp_accept_count |
| 335 | hasn't yet been incremented to take account of this connection. |
| 336 | |
| 337 | In order to minimize the cost (because this is going to happen for every |
| 338 | connection), do a preliminary selector test here. This saves ploughing through |
| 339 | the generalized logging code each time when the selector is false. If the |
| 340 | selector is set, check whether the host is on the list for logging. If not, |
| 341 | arrange to unset the selector in the subprocess. */ |
| 342 | |
| 343 | if (LOGGING(smtp_connection)) |
| 344 | { |
| 345 | uschar *list = hosts_connection_nolog; |
| 346 | memset(sender_host_cache, 0, sizeof(sender_host_cache)); |
| 347 | if (list != NULL && verify_check_host(&list) == OK) |
| 348 | save_log_selector &= ~L_smtp_connection; |
| 349 | else |
| 350 | log_write(L_smtp_connection, LOG_MAIN, "SMTP connection from %s " |
| 351 | "(TCP/IP connection count = %d)", whofrom->s, smtp_accept_count + 1); |
| 352 | } |
| 353 | |
| 354 | /* Now we can fork the accepting process; do a lookup tidy, just in case any |
| 355 | expansion above did a lookup. */ |
| 356 | |
| 357 | search_tidyup(); |
| 358 | pid = fork(); |
| 359 | |
| 360 | /* Handle the child process */ |
| 361 | |
| 362 | if (pid == 0) |
| 363 | { |
| 364 | int i; |
| 365 | int queue_only_reason = 0; |
| 366 | int old_pool = store_pool; |
| 367 | int save_debug_selector = debug_selector; |
| 368 | BOOL local_queue_only; |
| 369 | BOOL session_local_queue_only; |
| 370 | #ifdef SA_NOCLDWAIT |
| 371 | struct sigaction act; |
| 372 | #endif |
| 373 | |
| 374 | smtp_accept_count++; /* So that it includes this process */ |
| 375 | |
| 376 | /* May have been modified for the subprocess */ |
| 377 | |
| 378 | *log_selector = save_log_selector; |
| 379 | |
| 380 | /* Get the local interface address into permanent store */ |
| 381 | |
| 382 | store_pool = POOL_PERM; |
| 383 | interface_address = string_copy(interface_address); |
| 384 | store_pool = old_pool; |
| 385 | |
| 386 | /* Check for a tls-on-connect port */ |
| 387 | |
| 388 | if (host_is_tls_on_connect_port(interface_port)) tls_in.on_connect = TRUE; |
| 389 | |
| 390 | /* Expand smtp_active_hostname if required. We do not do this any earlier, |
| 391 | because it may depend on the local interface address (indeed, that is most |
| 392 | likely what it depends on.) */ |
| 393 | |
| 394 | smtp_active_hostname = primary_hostname; |
| 395 | if (raw_active_hostname) |
| 396 | { |
| 397 | uschar * nah = expand_string(raw_active_hostname); |
| 398 | if (!nah) |
| 399 | { |
| 400 | if (!f.expand_string_forcedfail) |
| 401 | { |
| 402 | log_write(0, LOG_MAIN|LOG_PANIC, "failed to expand \"%s\" " |
| 403 | "(smtp_active_hostname): %s", raw_active_hostname, |
| 404 | expand_string_message); |
| 405 | smtp_printf("421 Local configuration error; " |
| 406 | "please try again later.\r\n", FALSE); |
| 407 | mac_smtp_fflush(); |
| 408 | search_tidyup(); |
| 409 | exim_underbar_exit(EXIT_FAILURE); |
| 410 | } |
| 411 | } |
| 412 | else if (*nah) smtp_active_hostname = nah; |
| 413 | } |
| 414 | |
| 415 | /* Initialize the queueing flags */ |
| 416 | |
| 417 | queue_check_only(); |
| 418 | session_local_queue_only = queue_only; |
| 419 | |
| 420 | /* Close the listening sockets, and set the SIGCHLD handler to SIG_IGN. |
| 421 | We also attempt to set things up so that children are automatically reaped, |
| 422 | but just in case this isn't available, there's a paranoid waitpid() in the |
| 423 | loop too (except for systems where we are sure it isn't needed). See the more |
| 424 | extensive comment before the reception loop in exim.c for a fuller |
| 425 | explanation of this logic. */ |
| 426 | |
| 427 | for (i = 0; i < listen_socket_count; i++) (void)close(listen_sockets[i]); |
| 428 | |
| 429 | /* Set FD_CLOEXEC on the SMTP socket. We don't want any rogue child processes |
| 430 | to be able to communicate with them, under any circumstances. */ |
| 431 | (void)fcntl(accept_socket, F_SETFD, |
| 432 | fcntl(accept_socket, F_GETFD) | FD_CLOEXEC); |
| 433 | (void)fcntl(dup_accept_socket, F_SETFD, |
| 434 | fcntl(dup_accept_socket, F_GETFD) | FD_CLOEXEC); |
| 435 | |
| 436 | #ifdef SA_NOCLDWAIT |
| 437 | act.sa_handler = SIG_IGN; |
| 438 | sigemptyset(&(act.sa_mask)); |
| 439 | act.sa_flags = SA_NOCLDWAIT; |
| 440 | sigaction(SIGCHLD, &act, NULL); |
| 441 | #else |
| 442 | signal(SIGCHLD, SIG_IGN); |
| 443 | #endif |
| 444 | signal(SIGTERM, SIG_DFL); |
| 445 | |
| 446 | /* Attempt to get an id from the sending machine via the RFC 1413 |
| 447 | protocol. We do this in the sub-process in order not to hold up the |
| 448 | main process if there is any delay. Then set up the fullhost information |
| 449 | in case there is no HELO/EHLO. |
| 450 | |
| 451 | If debugging is enabled only for the daemon, we must turn if off while |
| 452 | finding the id, but turn it on again afterwards so that information about the |
| 453 | incoming connection is output. */ |
| 454 | |
| 455 | if (f.debug_daemon) debug_selector = 0; |
| 456 | verify_get_ident(IDENT_PORT); |
| 457 | host_build_sender_fullhost(); |
| 458 | debug_selector = save_debug_selector; |
| 459 | |
| 460 | DEBUG(D_any) |
| 461 | debug_printf("Process %d is handling incoming connection from %s\n", |
| 462 | (int)getpid(), sender_fullhost); |
| 463 | |
| 464 | /* Now disable debugging permanently if it's required only for the daemon |
| 465 | process. */ |
| 466 | |
| 467 | if (f.debug_daemon) debug_selector = 0; |
| 468 | |
| 469 | /* If there are too many child processes for immediate delivery, |
| 470 | set the session_local_queue_only flag, which is initialized from the |
| 471 | configured value and may therefore already be TRUE. Leave logging |
| 472 | till later so it will have a message id attached. Note that there is no |
| 473 | possibility of re-calculating this per-message, because the value of |
| 474 | smtp_accept_count does not change in this subprocess. */ |
| 475 | |
| 476 | if (smtp_accept_queue > 0 && smtp_accept_count > smtp_accept_queue) |
| 477 | { |
| 478 | session_local_queue_only = TRUE; |
| 479 | queue_only_reason = 1; |
| 480 | } |
| 481 | |
| 482 | /* Handle the start of the SMTP session, then loop, accepting incoming |
| 483 | messages from the SMTP connection. The end will come at the QUIT command, |
| 484 | when smtp_setup_msg() returns 0. A break in the connection causes the |
| 485 | process to die (see accept.c). |
| 486 | |
| 487 | NOTE: We do *not* call smtp_log_no_mail() if smtp_start_session() fails, |
| 488 | because a log line has already been written for all its failure exists |
| 489 | (usually "connection refused: <reason>") and writing another one is |
| 490 | unnecessary clutter. */ |
| 491 | |
| 492 | if (!smtp_start_session()) |
| 493 | { |
| 494 | mac_smtp_fflush(); |
| 495 | search_tidyup(); |
| 496 | exim_underbar_exit(EXIT_SUCCESS); |
| 497 | } |
| 498 | |
| 499 | for (;;) |
| 500 | { |
| 501 | int rc; |
| 502 | message_id[0] = 0; /* Clear out any previous message_id */ |
| 503 | reset_point = store_mark(); /* Save current store high water point */ |
| 504 | |
| 505 | DEBUG(D_any) |
| 506 | debug_printf("Process %d is ready for new message\n", (int)getpid()); |
| 507 | |
| 508 | /* Smtp_setup_msg() returns 0 on QUIT or if the call is from an |
| 509 | unacceptable host or if an ACL "drop" command was triggered, -1 on |
| 510 | connection lost, and +1 on validly reaching DATA. Receive_msg() almost |
| 511 | always returns TRUE when smtp_input is true; just retry if no message was |
| 512 | accepted (can happen for invalid message parameters). However, it can yield |
| 513 | FALSE if the connection was forcibly dropped by the DATA ACL. */ |
| 514 | |
| 515 | if ((rc = smtp_setup_msg()) > 0) |
| 516 | { |
| 517 | BOOL ok = receive_msg(FALSE); |
| 518 | search_tidyup(); /* Close cached databases */ |
| 519 | if (!ok) /* Connection was dropped */ |
| 520 | { |
| 521 | cancel_cutthrough_connection(TRUE, US"receive dropped"); |
| 522 | mac_smtp_fflush(); |
| 523 | smtp_log_no_mail(); /* Log no mail if configured */ |
| 524 | exim_underbar_exit(EXIT_SUCCESS); |
| 525 | } |
| 526 | if (message_id[0] == 0) continue; /* No message was accepted */ |
| 527 | } |
| 528 | else |
| 529 | { |
| 530 | if (smtp_out) |
| 531 | { |
| 532 | int fd = fileno(smtp_in); |
| 533 | uschar buf[128]; |
| 534 | |
| 535 | mac_smtp_fflush(); |
| 536 | /* drain socket, for clean TCP FINs */ |
| 537 | if (fcntl(fd, F_SETFL, O_NONBLOCK) == 0) |
| 538 | for(int i = 16; read(fd, buf, sizeof(buf)) > 0 && i > 0; ) i--; |
| 539 | } |
| 540 | cancel_cutthrough_connection(TRUE, US"message setup dropped"); |
| 541 | search_tidyup(); |
| 542 | smtp_log_no_mail(); /* Log no mail if configured */ |
| 543 | |
| 544 | /*XXX should we pause briefly, hoping that the client will be the |
| 545 | active TCP closer hence get the TCP_WAIT endpoint? */ |
| 546 | DEBUG(D_receive) debug_printf("SMTP>>(close on process exit)\n"); |
| 547 | exim_underbar_exit(rc ? EXIT_FAILURE : EXIT_SUCCESS); |
| 548 | } |
| 549 | |
| 550 | /* Show the recipients when debugging */ |
| 551 | |
| 552 | DEBUG(D_receive) |
| 553 | { |
| 554 | if (sender_address) |
| 555 | debug_printf("Sender: %s\n", sender_address); |
| 556 | if (recipients_list) |
| 557 | { |
| 558 | debug_printf("Recipients:\n"); |
| 559 | for (int i = 0; i < recipients_count; i++) |
| 560 | debug_printf(" %s\n", recipients_list[i].address); |
| 561 | } |
| 562 | } |
| 563 | |
| 564 | /* A message has been accepted. Clean up any previous delivery processes |
| 565 | that have completed and are defunct, on systems where they don't go away |
| 566 | by themselves (see comments when setting SIG_IGN above). On such systems |
| 567 | (if any) these delivery processes hang around after termination until |
| 568 | the next message is received. */ |
| 569 | |
| 570 | #ifndef SIG_IGN_WORKS |
| 571 | while (waitpid(-1, NULL, WNOHANG) > 0); |
| 572 | #endif |
| 573 | |
| 574 | /* Reclaim up the store used in accepting this message */ |
| 575 | |
| 576 | { |
| 577 | int r = receive_messagecount; |
| 578 | BOOL q = f.queue_only_policy; |
| 579 | smtp_reset(reset_point); |
| 580 | reset_point = NULL; |
| 581 | f.queue_only_policy = q; |
| 582 | receive_messagecount = r; |
| 583 | } |
| 584 | |
| 585 | /* If queue_only is set or if there are too many incoming connections in |
| 586 | existence, session_local_queue_only will be TRUE. If it is not, check |
| 587 | whether we have received too many messages in this session for immediate |
| 588 | delivery. */ |
| 589 | |
| 590 | if (!session_local_queue_only && |
| 591 | smtp_accept_queue_per_connection > 0 && |
| 592 | receive_messagecount > smtp_accept_queue_per_connection) |
| 593 | { |
| 594 | session_local_queue_only = TRUE; |
| 595 | queue_only_reason = 2; |
| 596 | } |
| 597 | |
| 598 | /* Initialize local_queue_only from session_local_queue_only. If it is not |
| 599 | true, and queue_only_load is set, check that the load average is below it. |
| 600 | If local_queue_only is set by this means, we also set if for the session if |
| 601 | queue_only_load_latch is true (the default). This means that, once set, |
| 602 | local_queue_only remains set for any subsequent messages on the same SMTP |
| 603 | connection. This is a deliberate choice; even though the load average may |
| 604 | fall, it doesn't seem right to deliver later messages on the same call when |
| 605 | not delivering earlier ones. However, the are special circumstances such as |
| 606 | very long-lived connections from scanning appliances where this is not the |
| 607 | best strategy. In such cases, queue_only_load_latch should be set false. */ |
| 608 | |
| 609 | if ( !(local_queue_only = session_local_queue_only) |
| 610 | && queue_only_load >= 0 |
| 611 | && (local_queue_only = (load_average = OS_GETLOADAVG()) > queue_only_load) |
| 612 | ) |
| 613 | { |
| 614 | queue_only_reason = 3; |
| 615 | if (queue_only_load_latch) session_local_queue_only = TRUE; |
| 616 | } |
| 617 | |
| 618 | /* Log the queueing here, when it will get a message id attached, but |
| 619 | not if queue_only is set (case 0). */ |
| 620 | |
| 621 | if (local_queue_only) switch(queue_only_reason) |
| 622 | { |
| 623 | case 1: log_write(L_delay_delivery, |
| 624 | LOG_MAIN, "no immediate delivery: too many connections " |
| 625 | "(%d, max %d)", smtp_accept_count, smtp_accept_queue); |
| 626 | break; |
| 627 | |
| 628 | case 2: log_write(L_delay_delivery, |
| 629 | LOG_MAIN, "no immediate delivery: more than %d messages " |
| 630 | "received in one connection", smtp_accept_queue_per_connection); |
| 631 | break; |
| 632 | |
| 633 | case 3: log_write(L_delay_delivery, |
| 634 | LOG_MAIN, "no immediate delivery: load average %.2f", |
| 635 | (double)load_average/1000.0); |
| 636 | break; |
| 637 | } |
| 638 | |
| 639 | /* If a delivery attempt is required, spin off a new process to handle it. |
| 640 | If we are not root, we have to re-exec exim unless deliveries are being |
| 641 | done unprivileged. */ |
| 642 | |
| 643 | else if (!f.queue_only_policy && !f.deliver_freeze) |
| 644 | { |
| 645 | pid_t dpid; |
| 646 | |
| 647 | /* Before forking, ensure that the C output buffer is flushed. Otherwise |
| 648 | anything that it in it will get duplicated, leading to duplicate copies |
| 649 | of the pending output. */ |
| 650 | |
| 651 | mac_smtp_fflush(); |
| 652 | |
| 653 | if ((dpid = fork()) == 0) |
| 654 | { |
| 655 | (void)fclose(smtp_in); |
| 656 | (void)fclose(smtp_out); |
| 657 | |
| 658 | /* Don't ever molest the parent's SSL connection, but do clean up |
| 659 | the data structures if necessary. */ |
| 660 | |
| 661 | #ifndef DISABLE_TLS |
| 662 | tls_close(NULL, TLS_NO_SHUTDOWN); |
| 663 | #endif |
| 664 | |
| 665 | /* Reset SIGHUP and SIGCHLD in the child in both cases. */ |
| 666 | |
| 667 | signal(SIGHUP, SIG_DFL); |
| 668 | signal(SIGCHLD, SIG_DFL); |
| 669 | signal(SIGTERM, SIG_DFL); |
| 670 | |
| 671 | if (geteuid() != root_uid && !deliver_drop_privilege) |
| 672 | { |
| 673 | signal(SIGALRM, SIG_DFL); |
| 674 | delivery_re_exec(CEE_EXEC_PANIC); |
| 675 | /* Control does not return here. */ |
| 676 | } |
| 677 | |
| 678 | /* No need to re-exec; SIGALRM remains set to the default handler */ |
| 679 | |
| 680 | (void) deliver_message(message_id, FALSE, FALSE); |
| 681 | search_tidyup(); |
| 682 | exim_underbar_exit(EXIT_SUCCESS); |
| 683 | } |
| 684 | |
| 685 | if (dpid > 0) |
| 686 | { |
| 687 | release_cutthrough_connection(US"passed for delivery"); |
| 688 | DEBUG(D_any) debug_printf("forked delivery process %d\n", (int)dpid); |
| 689 | } |
| 690 | else |
| 691 | { |
| 692 | cancel_cutthrough_connection(TRUE, US"delivery fork failed"); |
| 693 | log_write(0, LOG_MAIN|LOG_PANIC, "daemon: delivery process fork " |
| 694 | "failed: %s", strerror(errno)); |
| 695 | } |
| 696 | } |
| 697 | } |
| 698 | } |
| 699 | |
| 700 | |
| 701 | /* Carrying on in the parent daemon process... Can't do much if the fork |
| 702 | failed. Otherwise, keep count of the number of accepting processes and |
| 703 | remember the pid for ticking off when the child completes. */ |
| 704 | |
| 705 | if (pid < 0) |
| 706 | never_error(US"daemon: accept process fork failed", US"Fork failed", errno); |
| 707 | else |
| 708 | { |
| 709 | for (int i = 0; i < smtp_accept_max; ++i) |
| 710 | if (smtp_slots[i].pid <= 0) |
| 711 | { |
| 712 | smtp_slots[i].pid = pid; |
| 713 | /* Connection closes come asyncronously, so we cannot stack this store */ |
| 714 | if (smtp_accept_max_per_host) |
| 715 | smtp_slots[i].host_address = string_copy_malloc(sender_host_address); |
| 716 | smtp_accept_count++; |
| 717 | break; |
| 718 | } |
| 719 | DEBUG(D_any) debug_printf("%d SMTP accept process%s running\n", |
| 720 | smtp_accept_count, smtp_accept_count == 1 ? "" : "es"); |
| 721 | } |
| 722 | |
| 723 | /* Get here via goto in error cases */ |
| 724 | |
| 725 | ERROR_RETURN: |
| 726 | |
| 727 | /* Close the streams associated with the socket which will also close the |
| 728 | socket fds in this process. We can't do anything if fclose() fails, but |
| 729 | logging brings it to someone's attention. However, "connection reset by peer" |
| 730 | isn't really a problem, so skip that one. On Solaris, a dropped connection can |
| 731 | manifest itself as a broken pipe, so drop that one too. If the streams don't |
| 732 | exist, something went wrong while setting things up. Make sure the socket |
| 733 | descriptors are closed, in order to drop the connection. */ |
| 734 | |
| 735 | if (smtp_out) |
| 736 | { |
| 737 | if (fclose(smtp_out) != 0 && errno != ECONNRESET && errno != EPIPE) |
| 738 | log_write(0, LOG_MAIN|LOG_PANIC, "daemon: fclose(smtp_out) failed: %s", |
| 739 | strerror(errno)); |
| 740 | smtp_out = NULL; |
| 741 | } |
| 742 | else (void)close(accept_socket); |
| 743 | |
| 744 | if (smtp_in) |
| 745 | { |
| 746 | if (fclose(smtp_in) != 0 && errno != ECONNRESET && errno != EPIPE) |
| 747 | log_write(0, LOG_MAIN|LOG_PANIC, "daemon: fclose(smtp_in) failed: %s", |
| 748 | strerror(errno)); |
| 749 | smtp_in = NULL; |
| 750 | } |
| 751 | else (void)close(dup_accept_socket); |
| 752 | |
| 753 | /* Release any store used in this process, including the store used for holding |
| 754 | the incoming host address and an expanded active_hostname. */ |
| 755 | |
| 756 | log_close_all(); |
| 757 | interface_address = |
| 758 | sender_host_address = NULL; |
| 759 | store_reset(reset_point); |
| 760 | sender_host_address = NULL; |
| 761 | } |
| 762 | |
| 763 | |
| 764 | |
| 765 | |
| 766 | /************************************************* |
| 767 | * Check wildcard listen special cases * |
| 768 | *************************************************/ |
| 769 | |
| 770 | /* This function is used when binding and listening on lists of addresses and |
| 771 | ports. It tests for special cases of wildcard listening, when IPv4 and IPv6 |
| 772 | sockets may interact in different ways in different operating systems. It is |
| 773 | passed an error number, the list of listening addresses, and the current |
| 774 | address. Two checks are available: for a previous wildcard IPv6 address, or for |
| 775 | a following wildcard IPv4 address, in both cases on the same port. |
| 776 | |
| 777 | In practice, pairs of wildcard addresses should be adjacent in the address list |
| 778 | because they are sorted that way below. |
| 779 | |
| 780 | Arguments: |
| 781 | eno the error number |
| 782 | addresses the list of addresses |
| 783 | ipa the current IP address |
| 784 | back if TRUE, check for previous wildcard IPv6 address |
| 785 | if FALSE, check for a following wildcard IPv4 address |
| 786 | |
| 787 | Returns: TRUE or FALSE |
| 788 | */ |
| 789 | |
| 790 | static BOOL |
| 791 | check_special_case(int eno, ip_address_item *addresses, ip_address_item *ipa, |
| 792 | BOOL back) |
| 793 | { |
| 794 | ip_address_item *ipa2; |
| 795 | |
| 796 | /* For the "back" case, if the failure was "address in use" for a wildcard IPv4 |
| 797 | address, seek a previous IPv6 wildcard address on the same port. As it is |
| 798 | previous, it must have been successfully bound and be listening. Flag it as a |
| 799 | "6 including 4" listener. */ |
| 800 | |
| 801 | if (back) |
| 802 | { |
| 803 | if (eno != EADDRINUSE || ipa->address[0] != 0) return FALSE; |
| 804 | for (ipa2 = addresses; ipa2 != ipa; ipa2 = ipa2->next) |
| 805 | { |
| 806 | if (ipa2->address[1] == 0 && ipa2->port == ipa->port) |
| 807 | { |
| 808 | ipa2->v6_include_v4 = TRUE; |
| 809 | return TRUE; |
| 810 | } |
| 811 | } |
| 812 | } |
| 813 | |
| 814 | /* For the "forward" case, if the current address is a wildcard IPv6 address, |
| 815 | we seek a following wildcard IPv4 address on the same port. */ |
| 816 | |
| 817 | else |
| 818 | { |
| 819 | if (ipa->address[0] != ':' || ipa->address[1] != 0) return FALSE; |
| 820 | for (ipa2 = ipa->next; ipa2 != NULL; ipa2 = ipa2->next) |
| 821 | if (ipa2->address[0] == 0 && ipa->port == ipa2->port) return TRUE; |
| 822 | } |
| 823 | |
| 824 | return FALSE; |
| 825 | } |
| 826 | |
| 827 | |
| 828 | |
| 829 | |
| 830 | /************************************************* |
| 831 | * Handle terminating subprocesses * |
| 832 | *************************************************/ |
| 833 | |
| 834 | /* Handle the termination of child processes. Theoretically, this need be done |
| 835 | only when sigchld_seen is TRUE, but rumour has it that some systems lose |
| 836 | SIGCHLD signals at busy times, so to be on the safe side, this function is |
| 837 | called each time round. It shouldn't be too expensive. |
| 838 | |
| 839 | Arguments: none |
| 840 | Returns: nothing |
| 841 | */ |
| 842 | |
| 843 | static void |
| 844 | handle_ending_processes(void) |
| 845 | { |
| 846 | int status; |
| 847 | pid_t pid; |
| 848 | |
| 849 | while ((pid = waitpid(-1, &status, WNOHANG)) > 0) |
| 850 | { |
| 851 | DEBUG(D_any) |
| 852 | { |
| 853 | debug_printf("child %d ended: status=0x%x\n", (int)pid, status); |
| 854 | #ifdef WCOREDUMP |
| 855 | if (WIFEXITED(status)) |
| 856 | debug_printf(" normal exit, %d\n", WEXITSTATUS(status)); |
| 857 | else if (WIFSIGNALED(status)) |
| 858 | debug_printf(" signal exit, signal %d%s\n", WTERMSIG(status), |
| 859 | WCOREDUMP(status) ? " (core dumped)" : ""); |
| 860 | #endif |
| 861 | } |
| 862 | |
| 863 | /* If it's a listening daemon for which we are keeping track of individual |
| 864 | subprocesses, deal with an accepting process that has terminated. */ |
| 865 | |
| 866 | if (smtp_slots) |
| 867 | { |
| 868 | int i; |
| 869 | for (i = 0; i < smtp_accept_max; i++) |
| 870 | if (smtp_slots[i].pid == pid) |
| 871 | { |
| 872 | if (smtp_slots[i].host_address) |
| 873 | store_free(smtp_slots[i].host_address); |
| 874 | smtp_slots[i] = empty_smtp_slot; |
| 875 | if (--smtp_accept_count < 0) smtp_accept_count = 0; |
| 876 | DEBUG(D_any) debug_printf("%d SMTP accept process%s now running\n", |
| 877 | smtp_accept_count, (smtp_accept_count == 1)? "" : "es"); |
| 878 | break; |
| 879 | } |
| 880 | if (i < smtp_accept_max) continue; /* Found an accepting process */ |
| 881 | } |
| 882 | |
| 883 | /* If it wasn't an accepting process, see if it was a queue-runner |
| 884 | process that we are tracking. */ |
| 885 | |
| 886 | if (queue_pid_slots) |
| 887 | { |
| 888 | int max = atoi(CS expand_string(queue_run_max)); |
| 889 | for (int i = 0; i < max; i++) |
| 890 | if (queue_pid_slots[i] == pid) |
| 891 | { |
| 892 | queue_pid_slots[i] = 0; |
| 893 | if (--queue_run_count < 0) queue_run_count = 0; |
| 894 | DEBUG(D_any) debug_printf("%d queue-runner process%s now running\n", |
| 895 | queue_run_count, (queue_run_count == 1)? "" : "es"); |
| 896 | break; |
| 897 | } |
| 898 | } |
| 899 | } |
| 900 | } |
| 901 | |
| 902 | |
| 903 | |
| 904 | static void |
| 905 | set_pid_file_path(void) |
| 906 | { |
| 907 | if (override_pid_file_path) |
| 908 | pid_file_path = override_pid_file_path; |
| 909 | |
| 910 | if (!*pid_file_path) |
| 911 | pid_file_path = string_sprintf("%s/exim-daemon.pid", spool_directory); |
| 912 | } |
| 913 | |
| 914 | |
| 915 | /* Remove the daemon's pidfile. Note: runs with root privilege, |
| 916 | as a direct child of the daemon. Does not return. */ |
| 917 | |
| 918 | void |
| 919 | delete_pid_file(void) |
| 920 | { |
| 921 | uschar * daemon_pid = string_sprintf("%d\n", (int)getppid()); |
| 922 | FILE * f; |
| 923 | |
| 924 | set_pid_file_path(); |
| 925 | if ((f = Ufopen(pid_file_path, "rb"))) |
| 926 | { |
| 927 | if ( fgets(CS big_buffer, big_buffer_size, f) |
| 928 | && Ustrcmp(daemon_pid, big_buffer) == 0 |
| 929 | ) |
| 930 | if (Uunlink(pid_file_path) == 0) |
| 931 | { |
| 932 | DEBUG(D_any) |
| 933 | debug_printf("%s unlink: %s\n", pid_file_path, strerror(errno)); |
| 934 | } |
| 935 | else |
| 936 | DEBUG(D_any) |
| 937 | debug_printf("unlinked %s\n", pid_file_path); |
| 938 | fclose(f); |
| 939 | } |
| 940 | else |
| 941 | DEBUG(D_any) |
| 942 | debug_printf("%s\n", string_open_failed(errno, "pid file %s", |
| 943 | pid_file_path)); |
| 944 | exim_exit(EXIT_SUCCESS, US"pid file remover"); |
| 945 | } |
| 946 | |
| 947 | |
| 948 | /* Called by the daemon; exec a child to get the pid file deleted |
| 949 | since we may require privs for the containing directory */ |
| 950 | |
| 951 | static void |
| 952 | daemon_die(void) |
| 953 | { |
| 954 | int pid; |
| 955 | |
| 956 | if (f.running_in_test_harness || write_pid) |
| 957 | { |
| 958 | if ((pid = fork()) == 0) |
| 959 | { |
| 960 | if (override_pid_file_path) |
| 961 | (void)child_exec_exim(CEE_EXEC_PANIC, FALSE, NULL, FALSE, 3, |
| 962 | "-oP", override_pid_file_path, "-oPX"); |
| 963 | else |
| 964 | (void)child_exec_exim(CEE_EXEC_PANIC, FALSE, NULL, FALSE, 1, "-oPX"); |
| 965 | |
| 966 | /* Control never returns here. */ |
| 967 | } |
| 968 | if (pid > 0) |
| 969 | child_close(pid, 1); |
| 970 | } |
| 971 | exim_exit(EXIT_SUCCESS, US"daemon"); |
| 972 | } |
| 973 | |
| 974 | |
| 975 | /************************************************* |
| 976 | * Exim Daemon Mainline * |
| 977 | *************************************************/ |
| 978 | |
| 979 | /* The daemon can do two jobs, either of which is optional: |
| 980 | |
| 981 | (1) Listens for incoming SMTP calls and spawns off a sub-process to handle |
| 982 | each one. This is requested by the -bd option, with -oX specifying the SMTP |
| 983 | port on which to listen (for testing). |
| 984 | |
| 985 | (2) Spawns a queue-running process every so often. This is controlled by the |
| 986 | -q option with a an interval time. (If no time is given, a single queue run |
| 987 | is done from the main function, and control doesn't get here.) |
| 988 | |
| 989 | Root privilege is required in order to attach to port 25. Some systems require |
| 990 | it when calling socket() rather than bind(). To cope with all cases, we run as |
| 991 | root for both socket() and bind(). Some systems also require root in order to |
| 992 | write to the pid file directory. This function must therefore be called as root |
| 993 | if it is to work properly in all circumstances. Once the socket is bound and |
| 994 | the pid file written, root privilege is given up if there is an exim uid. |
| 995 | |
| 996 | There are no arguments to this function, and it never returns. */ |
| 997 | |
| 998 | void |
| 999 | daemon_go(void) |
| 1000 | { |
| 1001 | struct passwd *pw; |
| 1002 | int *listen_sockets = NULL; |
| 1003 | int listen_socket_count = 0; |
| 1004 | ip_address_item *addresses = NULL; |
| 1005 | time_t last_connection_time = (time_t)0; |
| 1006 | int local_queue_run_max = atoi(CS expand_string(queue_run_max)); |
| 1007 | |
| 1008 | /* If any debugging options are set, turn on the D_pid bit so that all |
| 1009 | debugging lines get the pid added. */ |
| 1010 | |
| 1011 | DEBUG(D_any|D_v) debug_selector |= D_pid; |
| 1012 | |
| 1013 | if (f.inetd_wait_mode) |
| 1014 | { |
| 1015 | listen_socket_count = 1; |
| 1016 | listen_sockets = store_get(sizeof(int), FALSE); |
| 1017 | (void) close(3); |
| 1018 | if (dup2(0, 3) == -1) |
| 1019 | log_write(0, LOG_MAIN|LOG_PANIC_DIE, |
| 1020 | "failed to dup inetd socket safely away: %s", strerror(errno)); |
| 1021 | |
| 1022 | listen_sockets[0] = 3; |
| 1023 | (void) close(0); |
| 1024 | (void) close(1); |
| 1025 | (void) close(2); |
| 1026 | exim_nullstd(); |
| 1027 | |
| 1028 | if (debug_file == stderr) |
| 1029 | { |
| 1030 | /* need a call to log_write before call to open debug_file, so that |
| 1031 | log.c:file_path has been initialised. This is unfortunate. */ |
| 1032 | log_write(0, LOG_MAIN, "debugging Exim in inetd wait mode starting"); |
| 1033 | |
| 1034 | fclose(debug_file); |
| 1035 | debug_file = NULL; |
| 1036 | exim_nullstd(); /* re-open fd2 after we just closed it again */ |
| 1037 | debug_logging_activate(US"-wait", NULL); |
| 1038 | } |
| 1039 | |
| 1040 | DEBUG(D_any) debug_printf("running in inetd wait mode\n"); |
| 1041 | |
| 1042 | /* As per below, when creating sockets ourselves, we handle tcp_nodelay for |
| 1043 | our own buffering; we assume though that inetd set the socket REUSEADDR. */ |
| 1044 | |
| 1045 | if (tcp_nodelay) |
| 1046 | if (setsockopt(3, IPPROTO_TCP, TCP_NODELAY, US &on, sizeof(on))) |
| 1047 | log_write(0, LOG_MAIN|LOG_PANIC_DIE, "failed to set socket NODELAY: %s", |
| 1048 | strerror(errno)); |
| 1049 | } |
| 1050 | |
| 1051 | |
| 1052 | if (f.inetd_wait_mode || f.daemon_listen) |
| 1053 | { |
| 1054 | /* If any option requiring a load average to be available during the |
| 1055 | reception of a message is set, call os_getloadavg() while we are root |
| 1056 | for those OS for which this is necessary the first time it is called (in |
| 1057 | order to perform an "open" on the kernel memory file). */ |
| 1058 | |
| 1059 | #ifdef LOAD_AVG_NEEDS_ROOT |
| 1060 | if (queue_only_load >= 0 || smtp_load_reserve >= 0 || |
| 1061 | (deliver_queue_load_max >= 0 && deliver_drop_privilege)) |
| 1062 | (void)os_getloadavg(); |
| 1063 | #endif |
| 1064 | } |
| 1065 | |
| 1066 | |
| 1067 | /* Do the preparation for setting up a listener on one or more interfaces, and |
| 1068 | possible on various ports. This is controlled by the combination of |
| 1069 | local_interfaces (which can set IP addresses and ports) and daemon_smtp_port |
| 1070 | (which is a list of default ports to use for those items in local_interfaces |
| 1071 | that do not specify a port). The -oX command line option can be used to |
| 1072 | override one or both of these options. |
| 1073 | |
| 1074 | If local_interfaces is not set, the default is to listen on all interfaces. |
| 1075 | When it is set, it can include "all IPvx interfaces" as an item. This is useful |
| 1076 | when different ports are in use. |
| 1077 | |
| 1078 | It turns out that listening on all interfaces is messy in an IPv6 world, |
| 1079 | because several different implementation approaches have been taken. This code |
| 1080 | is now supposed to work with all of them. The point of difference is whether an |
| 1081 | IPv6 socket that is listening on all interfaces will receive incoming IPv4 |
| 1082 | calls or not. We also have to cope with the case when IPv6 libraries exist, but |
| 1083 | there is no IPv6 support in the kernel. |
| 1084 | |
| 1085 | . On Solaris, an IPv6 socket will accept IPv4 calls, and give them as mapped |
| 1086 | addresses. However, if an IPv4 socket is also listening on all interfaces, |
| 1087 | calls are directed to the appropriate socket. |
| 1088 | |
| 1089 | . On (some versions of) Linux, an IPv6 socket will accept IPv4 calls, and |
| 1090 | give them as mapped addresses, but an attempt also to listen on an IPv4 |
| 1091 | socket on all interfaces causes an error. |
| 1092 | |
| 1093 | . On OpenBSD, an IPv6 socket will not accept IPv4 calls. You have to set up |
| 1094 | two sockets if you want to accept both kinds of call. |
| 1095 | |
| 1096 | . FreeBSD is like OpenBSD, but it has the IPV6_V6ONLY socket option, which |
| 1097 | can be turned off, to make it behave like the versions of Linux described |
| 1098 | above. |
| 1099 | |
| 1100 | . I heard a report that the USAGI IPv6 stack for Linux has implemented |
| 1101 | IPV6_V6ONLY. |
| 1102 | |
| 1103 | So, what we do when IPv6 is supported is as follows: |
| 1104 | |
| 1105 | (1) After it is set up, the list of interfaces is scanned for wildcard |
| 1106 | addresses. If an IPv6 and an IPv4 wildcard are both found for the same |
| 1107 | port, the list is re-arranged so that they are together, with the IPv6 |
| 1108 | wildcard first. |
| 1109 | |
| 1110 | (2) If the creation of a wildcard IPv6 socket fails, we just log the error and |
| 1111 | carry on if an IPv4 wildcard socket for the same port follows later in the |
| 1112 | list. This allows Exim to carry on in the case when the kernel has no IPv6 |
| 1113 | support. |
| 1114 | |
| 1115 | (3) Having created an IPv6 wildcard socket, we try to set IPV6_V6ONLY if that |
| 1116 | option is defined. However, if setting fails, carry on regardless (but log |
| 1117 | the incident). |
| 1118 | |
| 1119 | (4) If binding or listening on an IPv6 wildcard socket fails, it is a serious |
| 1120 | error. |
| 1121 | |
| 1122 | (5) If binding or listening on an IPv4 wildcard socket fails with the error |
| 1123 | EADDRINUSE, and a previous interface was an IPv6 wildcard for the same |
| 1124 | port (which must have succeeded or we wouldn't have got this far), we |
| 1125 | assume we are in the situation where just a single socket is permitted, |
| 1126 | and ignore the error. |
| 1127 | |
| 1128 | Phew! |
| 1129 | |
| 1130 | The preparation code decodes options and sets up the relevant data. We do this |
| 1131 | first, so that we can return non-zero if there are any syntax errors, and also |
| 1132 | write to stderr. */ |
| 1133 | |
| 1134 | if (f.daemon_listen && !f.inetd_wait_mode) |
| 1135 | { |
| 1136 | int *default_smtp_port; |
| 1137 | int sep; |
| 1138 | int pct = 0; |
| 1139 | uschar *s; |
| 1140 | const uschar * list; |
| 1141 | uschar *local_iface_source = US"local_interfaces"; |
| 1142 | ip_address_item *ipa; |
| 1143 | ip_address_item **pipa; |
| 1144 | |
| 1145 | /* If -oX was used, disable the writing of a pid file unless -oP was |
| 1146 | explicitly used to force it. Then scan the string given to -oX. Any items |
| 1147 | that contain neither a dot nor a colon are used to override daemon_smtp_port. |
| 1148 | Any other items are used to override local_interfaces. */ |
| 1149 | |
| 1150 | if (override_local_interfaces) |
| 1151 | { |
| 1152 | gstring * new_smtp_port = NULL; |
| 1153 | gstring * new_local_interfaces = NULL; |
| 1154 | |
| 1155 | if (!override_pid_file_path) write_pid = FALSE; |
| 1156 | |
| 1157 | list = override_local_interfaces; |
| 1158 | sep = 0; |
| 1159 | while ((s = string_nextinlist(&list, &sep, big_buffer, big_buffer_size))) |
| 1160 | { |
| 1161 | uschar joinstr[4]; |
| 1162 | gstring ** gp = Ustrpbrk(s, ".:") ? &new_local_interfaces : &new_smtp_port; |
| 1163 | |
| 1164 | if (!*gp) |
| 1165 | { |
| 1166 | joinstr[0] = sep; |
| 1167 | joinstr[1] = ' '; |
| 1168 | *gp = string_catn(*gp, US"<", 1); |
| 1169 | } |
| 1170 | |
| 1171 | *gp = string_catn(*gp, joinstr, 2); |
| 1172 | *gp = string_cat (*gp, s); |
| 1173 | } |
| 1174 | |
| 1175 | if (new_smtp_port) |
| 1176 | { |
| 1177 | daemon_smtp_port = string_from_gstring(new_smtp_port); |
| 1178 | DEBUG(D_any) debug_printf("daemon_smtp_port overridden by -oX:\n %s\n", |
| 1179 | daemon_smtp_port); |
| 1180 | } |
| 1181 | |
| 1182 | if (new_local_interfaces) |
| 1183 | { |
| 1184 | local_interfaces = string_from_gstring(new_local_interfaces); |
| 1185 | local_iface_source = US"-oX data"; |
| 1186 | DEBUG(D_any) debug_printf("local_interfaces overridden by -oX:\n %s\n", |
| 1187 | local_interfaces); |
| 1188 | } |
| 1189 | } |
| 1190 | |
| 1191 | /* Create a list of default SMTP ports, to be used if local_interfaces |
| 1192 | contains entries without explicit ports. First count the number of ports, then |
| 1193 | build a translated list in a vector. */ |
| 1194 | |
| 1195 | list = daemon_smtp_port; |
| 1196 | sep = 0; |
| 1197 | while ((s = string_nextinlist(&list, &sep, big_buffer, big_buffer_size))) |
| 1198 | pct++; |
| 1199 | default_smtp_port = store_get((pct+1) * sizeof(int), FALSE); |
| 1200 | list = daemon_smtp_port; |
| 1201 | sep = 0; |
| 1202 | for (pct = 0; |
| 1203 | (s = string_nextinlist(&list, &sep, big_buffer, big_buffer_size)); |
| 1204 | pct++) |
| 1205 | { |
| 1206 | if (isdigit(*s)) |
| 1207 | { |
| 1208 | uschar *end; |
| 1209 | default_smtp_port[pct] = Ustrtol(s, &end, 0); |
| 1210 | if (end != s + Ustrlen(s)) |
| 1211 | log_write(0, LOG_PANIC_DIE|LOG_CONFIG, "invalid SMTP port: %s", s); |
| 1212 | } |
| 1213 | else |
| 1214 | { |
| 1215 | struct servent *smtp_service = getservbyname(CS s, "tcp"); |
| 1216 | if (!smtp_service) |
| 1217 | log_write(0, LOG_PANIC_DIE|LOG_CONFIG, "TCP port \"%s\" not found", s); |
| 1218 | default_smtp_port[pct] = ntohs(smtp_service->s_port); |
| 1219 | } |
| 1220 | } |
| 1221 | default_smtp_port[pct] = 0; |
| 1222 | |
| 1223 | /* Check the list of TLS-on-connect ports and do name lookups if needed */ |
| 1224 | |
| 1225 | list = tls_in.on_connect_ports; |
| 1226 | sep = 0; |
| 1227 | while ((s = string_nextinlist(&list, &sep, big_buffer, big_buffer_size))) |
| 1228 | if (!isdigit(*s)) |
| 1229 | { |
| 1230 | gstring * g = NULL; |
| 1231 | |
| 1232 | list = tls_in.on_connect_ports; |
| 1233 | tls_in.on_connect_ports = NULL; |
| 1234 | sep = 0; |
| 1235 | while ((s = string_nextinlist(&list, &sep, big_buffer, big_buffer_size))) |
| 1236 | { |
| 1237 | if (!isdigit(*s)) |
| 1238 | { |
| 1239 | struct servent * smtp_service = getservbyname(CS s, "tcp"); |
| 1240 | if (!smtp_service) |
| 1241 | log_write(0, LOG_PANIC_DIE|LOG_CONFIG, "TCP port \"%s\" not found", s); |
| 1242 | s = string_sprintf("%d", (int)ntohs(smtp_service->s_port)); |
| 1243 | } |
| 1244 | g = string_append_listele(g, ':', s); |
| 1245 | } |
| 1246 | if (g) |
| 1247 | tls_in.on_connect_ports = g->s; |
| 1248 | break; |
| 1249 | } |
| 1250 | |
| 1251 | /* Create the list of local interfaces, possibly with ports included. This |
| 1252 | list may contain references to 0.0.0.0 and ::0 as wildcards. These special |
| 1253 | values are converted below. */ |
| 1254 | |
| 1255 | addresses = host_build_ifacelist(local_interfaces, local_iface_source); |
| 1256 | |
| 1257 | /* In the list of IP addresses, convert 0.0.0.0 into an empty string, and ::0 |
| 1258 | into the string ":". We use these to recognize wildcards in IPv4 and IPv6. In |
| 1259 | fact, many IP stacks recognize 0.0.0.0 and ::0 and handle them as wildcards |
| 1260 | anyway, but we need to know which are the wildcard addresses, and the shorter |
| 1261 | strings are neater. |
| 1262 | |
| 1263 | In the same scan, fill in missing port numbers from the default list. When |
| 1264 | there is more than one item in the list, extra items are created. */ |
| 1265 | |
| 1266 | for (ipa = addresses; ipa; ipa = ipa->next) |
| 1267 | { |
| 1268 | if (Ustrcmp(ipa->address, "0.0.0.0") == 0) |
| 1269 | ipa->address[0] = 0; |
| 1270 | else if (Ustrcmp(ipa->address, "::0") == 0) |
| 1271 | { |
| 1272 | ipa->address[0] = ':'; |
| 1273 | ipa->address[1] = 0; |
| 1274 | } |
| 1275 | |
| 1276 | if (ipa->port > 0) continue; |
| 1277 | |
| 1278 | if (daemon_smtp_port[0] <= 0) |
| 1279 | log_write(0, LOG_MAIN|LOG_PANIC_DIE, "no port specified for interface " |
| 1280 | "%s and daemon_smtp_port is unset; cannot start daemon", |
| 1281 | ipa->address[0] == 0 ? US"\"all IPv4\"" : |
| 1282 | ipa->address[1] == 0 ? US"\"all IPv6\"" : ipa->address); |
| 1283 | |
| 1284 | ipa->port = default_smtp_port[0]; |
| 1285 | for (int i = 1; default_smtp_port[i] > 0; i++) |
| 1286 | { |
| 1287 | ip_address_item *new = store_get(sizeof(ip_address_item), FALSE); |
| 1288 | |
| 1289 | memcpy(new->address, ipa->address, Ustrlen(ipa->address) + 1); |
| 1290 | new->port = default_smtp_port[i]; |
| 1291 | new->next = ipa->next; |
| 1292 | ipa->next = new; |
| 1293 | ipa = new; |
| 1294 | } |
| 1295 | } |
| 1296 | |
| 1297 | /* Scan the list of addresses for wildcards. If we find an IPv4 and an IPv6 |
| 1298 | wildcard for the same port, ensure that (a) they are together and (b) the |
| 1299 | IPv6 address comes first. This makes handling the messy features easier, and |
| 1300 | also simplifies the construction of the "daemon started" log line. */ |
| 1301 | |
| 1302 | pipa = &addresses; |
| 1303 | for (ipa = addresses; ipa; pipa = &ipa->next, ipa = ipa->next) |
| 1304 | { |
| 1305 | ip_address_item *ipa2; |
| 1306 | |
| 1307 | /* Handle an IPv4 wildcard */ |
| 1308 | |
| 1309 | if (ipa->address[0] == 0) |
| 1310 | for (ipa2 = ipa; ipa2->next; ipa2 = ipa2->next) |
| 1311 | { |
| 1312 | ip_address_item *ipa3 = ipa2->next; |
| 1313 | if (ipa3->address[0] == ':' && |
| 1314 | ipa3->address[1] == 0 && |
| 1315 | ipa3->port == ipa->port) |
| 1316 | { |
| 1317 | ipa2->next = ipa3->next; |
| 1318 | ipa3->next = ipa; |
| 1319 | *pipa = ipa3; |
| 1320 | break; |
| 1321 | } |
| 1322 | } |
| 1323 | |
| 1324 | /* Handle an IPv6 wildcard. */ |
| 1325 | |
| 1326 | else if (ipa->address[0] == ':' && ipa->address[1] == 0) |
| 1327 | for (ipa2 = ipa; ipa2->next; ipa2 = ipa2->next) |
| 1328 | { |
| 1329 | ip_address_item *ipa3 = ipa2->next; |
| 1330 | if (ipa3->address[0] == 0 && ipa3->port == ipa->port) |
| 1331 | { |
| 1332 | ipa2->next = ipa3->next; |
| 1333 | ipa3->next = ipa->next; |
| 1334 | ipa->next = ipa3; |
| 1335 | ipa = ipa3; |
| 1336 | break; |
| 1337 | } |
| 1338 | } |
| 1339 | } |
| 1340 | |
| 1341 | /* Get a vector to remember all the sockets in */ |
| 1342 | |
| 1343 | for (ipa = addresses; ipa; ipa = ipa->next) |
| 1344 | listen_socket_count++; |
| 1345 | listen_sockets = store_get(sizeof(int) * listen_socket_count, FALSE); |
| 1346 | |
| 1347 | } /* daemon_listen but not inetd_wait_mode */ |
| 1348 | |
| 1349 | if (f.daemon_listen) |
| 1350 | { |
| 1351 | |
| 1352 | /* Do a sanity check on the max connects value just to save us from getting |
| 1353 | a huge amount of store. */ |
| 1354 | |
| 1355 | if (smtp_accept_max > 4095) smtp_accept_max = 4096; |
| 1356 | |
| 1357 | /* There's no point setting smtp_accept_queue unless it is less than the max |
| 1358 | connects limit. The configuration reader ensures that the max is set if the |
| 1359 | queue-only option is set. */ |
| 1360 | |
| 1361 | if (smtp_accept_queue > smtp_accept_max) smtp_accept_queue = 0; |
| 1362 | |
| 1363 | /* Get somewhere to keep the list of SMTP accepting pids if we are keeping |
| 1364 | track of them for total number and queue/host limits. */ |
| 1365 | |
| 1366 | if (smtp_accept_max > 0) |
| 1367 | { |
| 1368 | smtp_slots = store_get(smtp_accept_max * sizeof(smtp_slot), FALSE); |
| 1369 | for (int i = 0; i < smtp_accept_max; i++) smtp_slots[i] = empty_smtp_slot; |
| 1370 | } |
| 1371 | } |
| 1372 | |
| 1373 | /* The variable background_daemon is always false when debugging, but |
| 1374 | can also be forced false in order to keep a non-debugging daemon in the |
| 1375 | foreground. If background_daemon is true, close all open file descriptors that |
| 1376 | we know about, but then re-open stdin, stdout, and stderr to /dev/null. Also |
| 1377 | do this for inetd_wait mode. |
| 1378 | |
| 1379 | This is protection against any called functions (in libraries, or in |
| 1380 | Perl, or whatever) that think they can write to stderr (or stdout). Before this |
| 1381 | was added, it was quite likely that an SMTP connection would use one of these |
| 1382 | file descriptors, in which case writing random stuff to it caused chaos. |
| 1383 | |
| 1384 | Then disconnect from the controlling terminal, Most modern Unixes seem to have |
| 1385 | setsid() for getting rid of the controlling terminal. For any OS that doesn't, |
| 1386 | setsid() can be #defined as a no-op, or as something else. */ |
| 1387 | |
| 1388 | if (f.background_daemon || f.inetd_wait_mode) |
| 1389 | { |
| 1390 | log_close_all(); /* Just in case anything was logged earlier */ |
| 1391 | search_tidyup(); /* Just in case any were used in reading the config. */ |
| 1392 | (void)close(0); /* Get rid of stdin/stdout/stderr */ |
| 1393 | (void)close(1); |
| 1394 | (void)close(2); |
| 1395 | exim_nullstd(); /* Connect stdin/stdout/stderr to /dev/null */ |
| 1396 | log_stderr = NULL; /* So no attempt to copy paniclog output */ |
| 1397 | } |
| 1398 | |
| 1399 | if (f.background_daemon) |
| 1400 | { |
| 1401 | /* If the parent process of this one has pid == 1, we are re-initializing the |
| 1402 | daemon as the result of a SIGHUP. In this case, there is no need to do |
| 1403 | anything, because the controlling terminal has long gone. Otherwise, fork, in |
| 1404 | case current process is a process group leader (see 'man setsid' for an |
| 1405 | explanation) before calling setsid(). */ |
| 1406 | |
| 1407 | if (getppid() != 1) |
| 1408 | { |
| 1409 | pid_t pid = fork(); |
| 1410 | if (pid < 0) log_write(0, LOG_MAIN|LOG_PANIC_DIE, |
| 1411 | "fork() failed when starting daemon: %s", strerror(errno)); |
| 1412 | if (pid > 0) exit(EXIT_SUCCESS); /* in parent process, just exit */ |
| 1413 | (void)setsid(); /* release controlling terminal */ |
| 1414 | } |
| 1415 | } |
| 1416 | |
| 1417 | /* We are now in the disconnected, daemon process (unless debugging). Set up |
| 1418 | the listening sockets if required. */ |
| 1419 | |
| 1420 | if (f.daemon_listen && !f.inetd_wait_mode) |
| 1421 | { |
| 1422 | int sk; |
| 1423 | ip_address_item *ipa; |
| 1424 | |
| 1425 | /* For each IP address, create a socket, bind it to the appropriate port, and |
| 1426 | start listening. See comments above about IPv6 sockets that may or may not |
| 1427 | accept IPv4 calls when listening on all interfaces. We also have to cope with |
| 1428 | the case of a system with IPv6 libraries, but no IPv6 support in the kernel. |
| 1429 | listening, provided a wildcard IPv4 socket for the same port follows. */ |
| 1430 | |
| 1431 | for (ipa = addresses, sk = 0; sk < listen_socket_count; ipa = ipa->next, sk++) |
| 1432 | { |
| 1433 | BOOL wildcard; |
| 1434 | ip_address_item *ipa2; |
| 1435 | int af; |
| 1436 | |
| 1437 | if (Ustrchr(ipa->address, ':') != NULL) |
| 1438 | { |
| 1439 | af = AF_INET6; |
| 1440 | wildcard = ipa->address[1] == 0; |
| 1441 | } |
| 1442 | else |
| 1443 | { |
| 1444 | af = AF_INET; |
| 1445 | wildcard = ipa->address[0] == 0; |
| 1446 | } |
| 1447 | |
| 1448 | if ((listen_sockets[sk] = ip_socket(SOCK_STREAM, af)) < 0) |
| 1449 | { |
| 1450 | if (check_special_case(0, addresses, ipa, FALSE)) |
| 1451 | { |
| 1452 | log_write(0, LOG_MAIN, "Failed to create IPv6 socket for wildcard " |
| 1453 | "listening (%s): will use IPv4", strerror(errno)); |
| 1454 | goto SKIP_SOCKET; |
| 1455 | } |
| 1456 | log_write(0, LOG_PANIC_DIE, "IPv%c socket creation failed: %s", |
| 1457 | (af == AF_INET6)? '6' : '4', strerror(errno)); |
| 1458 | } |
| 1459 | |
| 1460 | /* If this is an IPv6 wildcard socket, set IPV6_V6ONLY if that option is |
| 1461 | available. Just log failure (can get protocol not available, just like |
| 1462 | socket creation can). */ |
| 1463 | |
| 1464 | #ifdef IPV6_V6ONLY |
| 1465 | if (af == AF_INET6 && wildcard && |
| 1466 | setsockopt(listen_sockets[sk], IPPROTO_IPV6, IPV6_V6ONLY, CS (&on), |
| 1467 | sizeof(on)) < 0) |
| 1468 | log_write(0, LOG_MAIN, "Setting IPV6_V6ONLY on daemon's IPv6 wildcard " |
| 1469 | "socket failed (%s): carrying on without it", strerror(errno)); |
| 1470 | #endif /* IPV6_V6ONLY */ |
| 1471 | |
| 1472 | /* Set SO_REUSEADDR so that the daemon can be restarted while a connection |
| 1473 | is being handled. Without this, a connection will prevent reuse of the |
| 1474 | smtp port for listening. */ |
| 1475 | |
| 1476 | if (setsockopt(listen_sockets[sk], SOL_SOCKET, SO_REUSEADDR, |
| 1477 | US (&on), sizeof(on)) < 0) |
| 1478 | log_write(0, LOG_MAIN|LOG_PANIC_DIE, "setting SO_REUSEADDR on socket " |
| 1479 | "failed when starting daemon: %s", strerror(errno)); |
| 1480 | |
| 1481 | /* Set TCP_NODELAY; Exim does its own buffering. There is a switch to |
| 1482 | disable this because it breaks some broken clients. */ |
| 1483 | |
| 1484 | if (tcp_nodelay) setsockopt(listen_sockets[sk], IPPROTO_TCP, TCP_NODELAY, |
| 1485 | US (&on), sizeof(on)); |
| 1486 | |
| 1487 | /* Now bind the socket to the required port; if Exim is being restarted |
| 1488 | it may not always be possible to bind immediately, even with SO_REUSEADDR |
| 1489 | set, so try 10 times, waiting between each try. After 10 failures, we give |
| 1490 | up. In an IPv6 environment, if bind () fails with the error EADDRINUSE and |
| 1491 | we are doing wildcard IPv4 listening and there was a previous IPv6 wildcard |
| 1492 | address for the same port, ignore the error on the grounds that we must be |
| 1493 | in a system where the IPv6 socket accepts both kinds of call. This is |
| 1494 | necessary for (some release of) USAGI Linux; other IP stacks fail at the |
| 1495 | listen() stage instead. */ |
| 1496 | |
| 1497 | #ifdef TCP_FASTOPEN |
| 1498 | f.tcp_fastopen_ok = TRUE; |
| 1499 | #endif |
| 1500 | for(;;) |
| 1501 | { |
| 1502 | uschar *msg, *addr; |
| 1503 | if (ip_bind(listen_sockets[sk], af, ipa->address, ipa->port) >= 0) break; |
| 1504 | if (check_special_case(errno, addresses, ipa, TRUE)) |
| 1505 | { |
| 1506 | DEBUG(D_any) debug_printf("wildcard IPv4 bind() failed after IPv6 " |
| 1507 | "listen() success; EADDRINUSE ignored\n"); |
| 1508 | (void)close(listen_sockets[sk]); |
| 1509 | goto SKIP_SOCKET; |
| 1510 | } |
| 1511 | msg = US strerror(errno); |
| 1512 | addr = wildcard |
| 1513 | ? af == AF_INET6 |
| 1514 | ? US"(any IPv6)" |
| 1515 | : US"(any IPv4)" |
| 1516 | : ipa->address; |
| 1517 | if (daemon_startup_retries <= 0) |
| 1518 | log_write(0, LOG_MAIN|LOG_PANIC_DIE, |
| 1519 | "socket bind() to port %d for address %s failed: %s: " |
| 1520 | "daemon abandoned", ipa->port, addr, msg); |
| 1521 | log_write(0, LOG_MAIN, "socket bind() to port %d for address %s " |
| 1522 | "failed: %s: waiting %s before trying again (%d more %s)", |
| 1523 | ipa->port, addr, msg, readconf_printtime(daemon_startup_sleep), |
| 1524 | daemon_startup_retries, (daemon_startup_retries > 1)? "tries" : "try"); |
| 1525 | daemon_startup_retries--; |
| 1526 | sleep(daemon_startup_sleep); |
| 1527 | } |
| 1528 | |
| 1529 | DEBUG(D_any) |
| 1530 | if (wildcard) |
| 1531 | debug_printf("listening on all interfaces (IPv%c) port %d\n", |
| 1532 | af == AF_INET6 ? '6' : '4', ipa->port); |
| 1533 | else |
| 1534 | debug_printf("listening on %s port %d\n", ipa->address, ipa->port); |
| 1535 | |
| 1536 | #if defined(TCP_FASTOPEN) && !defined(__APPLE__) |
| 1537 | if ( f.tcp_fastopen_ok |
| 1538 | && setsockopt(listen_sockets[sk], IPPROTO_TCP, TCP_FASTOPEN, |
| 1539 | &smtp_connect_backlog, sizeof(smtp_connect_backlog))) |
| 1540 | { |
| 1541 | DEBUG(D_any) debug_printf("setsockopt FASTOPEN: %s\n", strerror(errno)); |
| 1542 | f.tcp_fastopen_ok = FALSE; |
| 1543 | } |
| 1544 | #endif |
| 1545 | |
| 1546 | /* Start listening on the bound socket, establishing the maximum backlog of |
| 1547 | connections that is allowed. On success, continue to the next address. */ |
| 1548 | |
| 1549 | if (listen(listen_sockets[sk], smtp_connect_backlog) >= 0) |
| 1550 | { |
| 1551 | #if defined(TCP_FASTOPEN) && defined(__APPLE__) |
| 1552 | if ( f.tcp_fastopen_ok |
| 1553 | && setsockopt(listen_sockets[sk], IPPROTO_TCP, TCP_FASTOPEN, |
| 1554 | &on, sizeof(on))) |
| 1555 | { |
| 1556 | DEBUG(D_any) debug_printf("setsockopt FASTOPEN: %s\n", strerror(errno)); |
| 1557 | f.tcp_fastopen_ok = FALSE; |
| 1558 | } |
| 1559 | #endif |
| 1560 | continue; |
| 1561 | } |
| 1562 | |
| 1563 | /* Listening has failed. In an IPv6 environment, as for bind(), if listen() |
| 1564 | fails with the error EADDRINUSE and we are doing IPv4 wildcard listening |
| 1565 | and there was a previous successful IPv6 wildcard listen on the same port, |
| 1566 | we want to ignore the error on the grounds that we must be in a system |
| 1567 | where the IPv6 socket accepts both kinds of call. */ |
| 1568 | |
| 1569 | if (!check_special_case(errno, addresses, ipa, TRUE)) |
| 1570 | log_write(0, LOG_PANIC_DIE, "listen() failed on interface %s: %s", |
| 1571 | wildcard |
| 1572 | ? af == AF_INET6 ? US"(any IPv6)" : US"(any IPv4)" : ipa->address, |
| 1573 | strerror(errno)); |
| 1574 | |
| 1575 | DEBUG(D_any) debug_printf("wildcard IPv4 listen() failed after IPv6 " |
| 1576 | "listen() success; EADDRINUSE ignored\n"); |
| 1577 | (void)close(listen_sockets[sk]); |
| 1578 | |
| 1579 | /* Come here if there has been a problem with the socket which we |
| 1580 | are going to ignore. We remove the address from the chain, and back up the |
| 1581 | counts. */ |
| 1582 | |
| 1583 | SKIP_SOCKET: |
| 1584 | sk--; /* Back up the count */ |
| 1585 | listen_socket_count--; /* Reduce the total */ |
| 1586 | if (ipa == addresses) addresses = ipa->next; else |
| 1587 | { |
| 1588 | for (ipa2 = addresses; ipa2->next != ipa; ipa2 = ipa2->next); |
| 1589 | ipa2->next = ipa->next; |
| 1590 | ipa = ipa2; |
| 1591 | } |
| 1592 | } /* End of bind/listen loop for each address */ |
| 1593 | } /* End of setup for listening */ |
| 1594 | |
| 1595 | |
| 1596 | /* If we are not listening, we want to write a pid file only if -oP was |
| 1597 | explicitly given. */ |
| 1598 | |
| 1599 | else if (!override_pid_file_path) |
| 1600 | write_pid = FALSE; |
| 1601 | |
| 1602 | /* Write the pid to a known file for assistance in identification, if required. |
| 1603 | We do this before giving up root privilege, because on some systems it is |
| 1604 | necessary to be root in order to write into the pid file directory. There's |
| 1605 | nothing to stop multiple daemons running, as long as no more than one listens |
| 1606 | on a given TCP/IP port on the same interface(s). However, in these |
| 1607 | circumstances it gets far too complicated to mess with pid file names |
| 1608 | automatically. Consequently, Exim 4 writes a pid file only |
| 1609 | |
| 1610 | (a) When running in the test harness, or |
| 1611 | (b) When -bd is used and -oX is not used, or |
| 1612 | (c) When -oP is used to supply a path. |
| 1613 | |
| 1614 | The variable daemon_write_pid is used to control this. */ |
| 1615 | |
| 1616 | if (f.running_in_test_harness || write_pid) |
| 1617 | { |
| 1618 | FILE *f; |
| 1619 | |
| 1620 | set_pid_file_path(); |
| 1621 | if ((f = modefopen(pid_file_path, "wb", 0644))) |
| 1622 | { |
| 1623 | (void)fprintf(f, "%d\n", (int)getpid()); |
| 1624 | (void)fclose(f); |
| 1625 | DEBUG(D_any) debug_printf("pid written to %s\n", pid_file_path); |
| 1626 | } |
| 1627 | else |
| 1628 | DEBUG(D_any) |
| 1629 | debug_printf("%s\n", string_open_failed(errno, "pid file %s", |
| 1630 | pid_file_path)); |
| 1631 | } |
| 1632 | |
| 1633 | /* Set up the handler for SIGHUP, which causes a restart of the daemon. */ |
| 1634 | |
| 1635 | sighup_seen = FALSE; |
| 1636 | signal(SIGHUP, sighup_handler); |
| 1637 | |
| 1638 | /* Give up root privilege at this point (assuming that exim_uid and exim_gid |
| 1639 | are not root). The third argument controls the running of initgroups(). |
| 1640 | Normally we do this, in order to set up the groups for the Exim user. However, |
| 1641 | if we are not root at this time - some odd installations run that way - we |
| 1642 | cannot do this. */ |
| 1643 | |
| 1644 | exim_setugid(exim_uid, exim_gid, geteuid()==root_uid, US"running as a daemon"); |
| 1645 | |
| 1646 | /* Update the originator_xxx fields so that received messages as listed as |
| 1647 | coming from Exim, not whoever started the daemon. */ |
| 1648 | |
| 1649 | originator_uid = exim_uid; |
| 1650 | originator_gid = exim_gid; |
| 1651 | originator_login = (pw = getpwuid(exim_uid)) |
| 1652 | ? string_copy_perm(US pw->pw_name, FALSE) : US"exim"; |
| 1653 | |
| 1654 | /* Get somewhere to keep the list of queue-runner pids if we are keeping track |
| 1655 | of them (and also if we are doing queue runs). */ |
| 1656 | |
| 1657 | if (queue_interval > 0 && local_queue_run_max > 0) |
| 1658 | { |
| 1659 | queue_pid_slots = store_get(local_queue_run_max * sizeof(pid_t), FALSE); |
| 1660 | for (int i = 0; i < local_queue_run_max; i++) queue_pid_slots[i] = 0; |
| 1661 | } |
| 1662 | |
| 1663 | /* Set up the handler for termination of child processes, and the one |
| 1664 | telling us to die. */ |
| 1665 | |
| 1666 | sigchld_seen = FALSE; |
| 1667 | os_non_restarting_signal(SIGCHLD, main_sigchld_handler); |
| 1668 | |
| 1669 | sigterm_seen = FALSE; |
| 1670 | os_non_restarting_signal(SIGTERM, main_sigterm_handler); |
| 1671 | |
| 1672 | /* If we are to run the queue periodically, pretend the alarm has just gone |
| 1673 | off. This will cause the first queue-runner to get kicked off straight away. */ |
| 1674 | |
| 1675 | sigalrm_seen = (queue_interval > 0); |
| 1676 | |
| 1677 | /* Log the start up of a daemon - at least one of listening or queue running |
| 1678 | must be set up. */ |
| 1679 | |
| 1680 | if (f.inetd_wait_mode) |
| 1681 | { |
| 1682 | uschar *p = big_buffer; |
| 1683 | |
| 1684 | if (inetd_wait_timeout >= 0) |
| 1685 | sprintf(CS p, "terminating after %d seconds", inetd_wait_timeout); |
| 1686 | else |
| 1687 | sprintf(CS p, "with no wait timeout"); |
| 1688 | |
| 1689 | log_write(0, LOG_MAIN, |
| 1690 | "exim %s daemon started: pid=%d, launched with listening socket, %s", |
| 1691 | version_string, getpid(), big_buffer); |
| 1692 | set_process_info("daemon(%s): pre-listening socket", version_string); |
| 1693 | |
| 1694 | /* set up the timeout logic */ |
| 1695 | sigalrm_seen = 1; |
| 1696 | } |
| 1697 | |
| 1698 | else if (f.daemon_listen) |
| 1699 | { |
| 1700 | int smtp_ports = 0; |
| 1701 | int smtps_ports = 0; |
| 1702 | ip_address_item * ipa; |
| 1703 | uschar * p; |
| 1704 | uschar * qinfo = queue_interval > 0 |
| 1705 | ? string_sprintf("-q%s", readconf_printtime(queue_interval)) |
| 1706 | : US"no queue runs"; |
| 1707 | |
| 1708 | /* Build a list of listening addresses in big_buffer, but limit it to 10 |
| 1709 | items. The style is for backwards compatibility. |
| 1710 | |
| 1711 | It is now possible to have some ports listening for SMTPS (the old, |
| 1712 | deprecated protocol that starts TLS without using STARTTLS), and others |
| 1713 | listening for standard SMTP. Keep their listings separate. */ |
| 1714 | |
| 1715 | for (int j = 0, i; j < 2; j++) |
| 1716 | { |
| 1717 | for (i = 0, ipa = addresses; i < 10 && ipa; i++, ipa = ipa->next) |
| 1718 | { |
| 1719 | /* First time round, look for SMTP ports; second time round, look for |
| 1720 | SMTPS ports. Build IP+port strings. */ |
| 1721 | |
| 1722 | if (host_is_tls_on_connect_port(ipa->port) == (j > 0)) |
| 1723 | { |
| 1724 | if (j == 0) |
| 1725 | smtp_ports++; |
| 1726 | else |
| 1727 | smtps_ports++; |
| 1728 | |
| 1729 | /* Now the information about the port (and sometimes interface) */ |
| 1730 | |
| 1731 | if (ipa->address[0] == ':' && ipa->address[1] == 0) |
| 1732 | { /* v6 wildcard */ |
| 1733 | if (ipa->next && ipa->next->address[0] == 0 && |
| 1734 | ipa->next->port == ipa->port) |
| 1735 | { |
| 1736 | ipa->log = string_sprintf(" port %d (IPv6 and IPv4)", ipa->port); |
| 1737 | (ipa = ipa->next)->log = NULL; |
| 1738 | } |
| 1739 | else if (ipa->v6_include_v4) |
| 1740 | ipa->log = string_sprintf(" port %d (IPv6 with IPv4)", ipa->port); |
| 1741 | else |
| 1742 | ipa->log = string_sprintf(" port %d (IPv6)", ipa->port); |
| 1743 | } |
| 1744 | else if (ipa->address[0] == 0) /* v4 wildcard */ |
| 1745 | ipa->log = string_sprintf(" port %d (IPv4)", ipa->port); |
| 1746 | else /* check for previously-seen IP */ |
| 1747 | { |
| 1748 | ip_address_item * i2; |
| 1749 | for (i2 = addresses; i2 != ipa; i2 = i2->next) |
| 1750 | if ( host_is_tls_on_connect_port(i2->port) == (j > 0) |
| 1751 | && Ustrcmp(ipa->address, i2->address) == 0 |
| 1752 | ) |
| 1753 | { /* found; append port to list */ |
| 1754 | for (p = i2->log; *p; ) p++; /* end of existing string */ |
| 1755 | if (*--p == '}') *p = '\0'; /* drop EOL */ |
| 1756 | while (isdigit(*--p)) ; /* char before port */ |
| 1757 | |
| 1758 | i2->log = *p == ':' /* no list yet? */ |
| 1759 | ? string_sprintf("%.*s{%s,%d}", |
| 1760 | (int)(p - i2->log + 1), i2->log, p+1, ipa->port) |
| 1761 | : string_sprintf("%s,%d}", i2->log, ipa->port); |
| 1762 | ipa->log = NULL; |
| 1763 | break; |
| 1764 | } |
| 1765 | if (i2 == ipa) /* first-time IP */ |
| 1766 | ipa->log = string_sprintf(" [%s]:%d", ipa->address, ipa->port); |
| 1767 | } |
| 1768 | } |
| 1769 | } |
| 1770 | } |
| 1771 | |
| 1772 | p = big_buffer; |
| 1773 | for (int j = 0, i; j < 2; j++) |
| 1774 | { |
| 1775 | /* First time round, look for SMTP ports; second time round, look for |
| 1776 | SMTPS ports. For the first one of each, insert leading text. */ |
| 1777 | |
| 1778 | if (j == 0) |
| 1779 | { |
| 1780 | if (smtp_ports > 0) |
| 1781 | p += sprintf(CS p, "SMTP on"); |
| 1782 | } |
| 1783 | else |
| 1784 | if (smtps_ports > 0) |
| 1785 | p += sprintf(CS p, "%sSMTPS on", |
| 1786 | smtp_ports == 0 ? "" : " and for "); |
| 1787 | |
| 1788 | /* Now the information about the port (and sometimes interface) */ |
| 1789 | |
| 1790 | for (i = 0, ipa = addresses; i < 10 && ipa; i++, ipa = ipa->next) |
| 1791 | if (host_is_tls_on_connect_port(ipa->port) == (j > 0)) |
| 1792 | if (ipa->log) |
| 1793 | p += sprintf(CS p, "%s", ipa->log); |
| 1794 | |
| 1795 | if (ipa) |
| 1796 | p += sprintf(CS p, " ..."); |
| 1797 | } |
| 1798 | |
| 1799 | log_write(0, LOG_MAIN, |
| 1800 | "exim %s daemon started: pid=%d, %s, listening for %s", |
| 1801 | version_string, getpid(), qinfo, big_buffer); |
| 1802 | set_process_info("daemon(%s): %s, listening for %s", |
| 1803 | version_string, qinfo, big_buffer); |
| 1804 | } |
| 1805 | |
| 1806 | else |
| 1807 | { |
| 1808 | uschar * s = *queue_name |
| 1809 | ? string_sprintf("-qG%s/%s", queue_name, readconf_printtime(queue_interval)) |
| 1810 | : string_sprintf("-q%s", readconf_printtime(queue_interval)); |
| 1811 | log_write(0, LOG_MAIN, |
| 1812 | "exim %s daemon started: pid=%d, %s, not listening for SMTP", |
| 1813 | version_string, getpid(), s); |
| 1814 | set_process_info("daemon(%s): %s, not listening", version_string, s); |
| 1815 | } |
| 1816 | |
| 1817 | /* Do any work it might be useful to amortize over our children |
| 1818 | (eg: compile regex) */ |
| 1819 | |
| 1820 | dns_pattern_init(); |
| 1821 | smtp_deliver_init(); /* Used for callouts */ |
| 1822 | |
| 1823 | #ifndef DISABLE_DKIM |
| 1824 | { |
| 1825 | # ifdef MEASURE_TIMING |
| 1826 | struct timeval t0; |
| 1827 | gettimeofday(&t0, NULL); |
| 1828 | # endif |
| 1829 | dkim_exim_init(); |
| 1830 | # ifdef MEASURE_TIMING |
| 1831 | report_time_since(&t0, US"dkim_exim_init (delta)"); |
| 1832 | # endif |
| 1833 | } |
| 1834 | #endif |
| 1835 | |
| 1836 | #ifdef WITH_CONTENT_SCAN |
| 1837 | malware_init(); |
| 1838 | #endif |
| 1839 | #ifdef SUPPORT_SPF |
| 1840 | spf_init(); |
| 1841 | #endif |
| 1842 | |
| 1843 | /* Close the log so it can be renamed and moved. In the few cases below where |
| 1844 | this long-running process writes to the log (always exceptional conditions), it |
| 1845 | closes the log afterwards, for the same reason. */ |
| 1846 | |
| 1847 | log_close_all(); |
| 1848 | |
| 1849 | DEBUG(D_any) debug_print_ids(US"daemon running with"); |
| 1850 | |
| 1851 | /* Any messages accepted via this route are going to be SMTP. */ |
| 1852 | |
| 1853 | smtp_input = TRUE; |
| 1854 | |
| 1855 | #ifdef MEASURE_TIMING |
| 1856 | report_time_since(×tamp_startup, US"daemon loop start"); /* testcase 0022 */ |
| 1857 | #endif |
| 1858 | |
| 1859 | /* Enter the never-ending loop... */ |
| 1860 | |
| 1861 | for (;;) |
| 1862 | { |
| 1863 | #if HAVE_IPV6 |
| 1864 | struct sockaddr_in6 accepted; |
| 1865 | #else |
| 1866 | struct sockaddr_in accepted; |
| 1867 | #endif |
| 1868 | |
| 1869 | EXIM_SOCKLEN_T len; |
| 1870 | pid_t pid; |
| 1871 | |
| 1872 | if (sigterm_seen) |
| 1873 | daemon_die(); /* Does not return */ |
| 1874 | |
| 1875 | /* This code is placed first in the loop, so that it gets obeyed at the |
| 1876 | start, before the first wait, for the queue-runner case, so that the first |
| 1877 | one can be started immediately. |
| 1878 | |
| 1879 | The other option is that we have an inetd wait timeout specified to -bw. */ |
| 1880 | |
| 1881 | if (sigalrm_seen) |
| 1882 | { |
| 1883 | if (inetd_wait_timeout > 0) |
| 1884 | { |
| 1885 | time_t resignal_interval = inetd_wait_timeout; |
| 1886 | |
| 1887 | if (last_connection_time == (time_t)0) |
| 1888 | { |
| 1889 | DEBUG(D_any) |
| 1890 | debug_printf("inetd wait timeout expired, but still not seen first message, ignoring\n"); |
| 1891 | } |
| 1892 | else |
| 1893 | { |
| 1894 | time_t now = time(NULL); |
| 1895 | if (now == (time_t)-1) |
| 1896 | { |
| 1897 | DEBUG(D_any) debug_printf("failed to get time: %s\n", strerror(errno)); |
| 1898 | } |
| 1899 | else |
| 1900 | { |
| 1901 | if ((now - last_connection_time) >= inetd_wait_timeout) |
| 1902 | { |
| 1903 | DEBUG(D_any) |
| 1904 | debug_printf("inetd wait timeout %d expired, ending daemon\n", |
| 1905 | inetd_wait_timeout); |
| 1906 | log_write(0, LOG_MAIN, "exim %s daemon terminating, inetd wait timeout reached.\n", |
| 1907 | version_string); |
| 1908 | exit(EXIT_SUCCESS); |
| 1909 | } |
| 1910 | else |
| 1911 | { |
| 1912 | resignal_interval -= (now - last_connection_time); |
| 1913 | } |
| 1914 | } |
| 1915 | } |
| 1916 | |
| 1917 | sigalrm_seen = FALSE; |
| 1918 | ALARM(resignal_interval); |
| 1919 | } |
| 1920 | |
| 1921 | else |
| 1922 | { |
| 1923 | DEBUG(D_any) debug_printf("SIGALRM received\n"); |
| 1924 | |
| 1925 | /* Do a full queue run in a child process, if required, unless we already |
| 1926 | have enough queue runners on the go. If we are not running as root, a |
| 1927 | re-exec is required. */ |
| 1928 | |
| 1929 | if (queue_interval > 0 && |
| 1930 | (local_queue_run_max <= 0 || queue_run_count < local_queue_run_max)) |
| 1931 | { |
| 1932 | if ((pid = fork()) == 0) |
| 1933 | { |
| 1934 | DEBUG(D_any) debug_printf("Starting queue-runner: pid %d\n", |
| 1935 | (int)getpid()); |
| 1936 | |
| 1937 | /* Disable debugging if it's required only for the daemon process. We |
| 1938 | leave the above message, because it ties up with the "child ended" |
| 1939 | debugging messages. */ |
| 1940 | |
| 1941 | if (f.debug_daemon) debug_selector = 0; |
| 1942 | |
| 1943 | /* Close any open listening sockets in the child */ |
| 1944 | |
| 1945 | for (int sk = 0; sk < listen_socket_count; sk++) |
| 1946 | (void)close(listen_sockets[sk]); |
| 1947 | |
| 1948 | /* Reset SIGHUP and SIGCHLD in the child in both cases. */ |
| 1949 | |
| 1950 | signal(SIGHUP, SIG_DFL); |
| 1951 | signal(SIGCHLD, SIG_DFL); |
| 1952 | signal(SIGTERM, SIG_DFL); |
| 1953 | |
| 1954 | /* Re-exec if privilege has been given up, unless deliver_drop_ |
| 1955 | privilege is set. Reset SIGALRM before exec(). */ |
| 1956 | |
| 1957 | if (geteuid() != root_uid && !deliver_drop_privilege) |
| 1958 | { |
| 1959 | uschar opt[8]; |
| 1960 | uschar *p = opt; |
| 1961 | uschar *extra[5]; |
| 1962 | int extracount = 1; |
| 1963 | |
| 1964 | signal(SIGALRM, SIG_DFL); |
| 1965 | *p++ = '-'; |
| 1966 | *p++ = 'q'; |
| 1967 | if (f.queue_2stage) *p++ = 'q'; |
| 1968 | if (f.queue_run_first_delivery) *p++ = 'i'; |
| 1969 | if (f.queue_run_force) *p++ = 'f'; |
| 1970 | if (f.deliver_force_thaw) *p++ = 'f'; |
| 1971 | if (f.queue_run_local) *p++ = 'l'; |
| 1972 | *p = 0; |
| 1973 | extra[0] = queue_name |
| 1974 | ? string_sprintf("%sG%s", opt, queue_name) : opt; |
| 1975 | |
| 1976 | /* If -R or -S were on the original command line, ensure they get |
| 1977 | passed on. */ |
| 1978 | |
| 1979 | if (deliver_selectstring) |
| 1980 | { |
| 1981 | extra[extracount++] = f.deliver_selectstring_regex ? US"-Rr" : US"-R"; |
| 1982 | extra[extracount++] = deliver_selectstring; |
| 1983 | } |
| 1984 | |
| 1985 | if (deliver_selectstring_sender) |
| 1986 | { |
| 1987 | extra[extracount++] = f.deliver_selectstring_sender_regex |
| 1988 | ? US"-Sr" : US"-S"; |
| 1989 | extra[extracount++] = deliver_selectstring_sender; |
| 1990 | } |
| 1991 | |
| 1992 | /* Overlay this process with a new execution. */ |
| 1993 | |
| 1994 | (void)child_exec_exim(CEE_EXEC_PANIC, FALSE, NULL, TRUE, extracount, |
| 1995 | extra[0], extra[1], extra[2], extra[3], extra[4]); |
| 1996 | |
| 1997 | /* Control never returns here. */ |
| 1998 | } |
| 1999 | |
| 2000 | /* No need to re-exec; SIGALRM remains set to the default handler */ |
| 2001 | |
| 2002 | queue_run(NULL, NULL, FALSE); |
| 2003 | exim_underbar_exit(EXIT_SUCCESS); |
| 2004 | } |
| 2005 | |
| 2006 | if (pid < 0) |
| 2007 | { |
| 2008 | log_write(0, LOG_MAIN|LOG_PANIC, "daemon: fork of queue-runner " |
| 2009 | "process failed: %s", strerror(errno)); |
| 2010 | log_close_all(); |
| 2011 | } |
| 2012 | else |
| 2013 | { |
| 2014 | for (int i = 0; i < local_queue_run_max; ++i) |
| 2015 | if (queue_pid_slots[i] <= 0) |
| 2016 | { |
| 2017 | queue_pid_slots[i] = pid; |
| 2018 | queue_run_count++; |
| 2019 | break; |
| 2020 | } |
| 2021 | DEBUG(D_any) debug_printf("%d queue-runner process%s running\n", |
| 2022 | queue_run_count, queue_run_count == 1 ? "" : "es"); |
| 2023 | } |
| 2024 | } |
| 2025 | |
| 2026 | /* Reset the alarm clock */ |
| 2027 | |
| 2028 | sigalrm_seen = FALSE; |
| 2029 | ALARM(queue_interval); |
| 2030 | } |
| 2031 | |
| 2032 | } /* sigalrm_seen */ |
| 2033 | |
| 2034 | |
| 2035 | /* Sleep till a connection happens if listening, and handle the connection if |
| 2036 | that is why we woke up. The FreeBSD operating system requires the use of |
| 2037 | select() before accept() because the latter function is not interrupted by |
| 2038 | a signal, and we want to wake up for SIGCHLD and SIGALRM signals. Some other |
| 2039 | OS do notice signals in accept() but it does no harm to have the select() |
| 2040 | in for all of them - and it won't then be a lurking problem for ports to |
| 2041 | new OS. In fact, the later addition of listening on specific interfaces only |
| 2042 | requires this way of working anyway. */ |
| 2043 | |
| 2044 | if (f.daemon_listen) |
| 2045 | { |
| 2046 | int lcount, select_errno; |
| 2047 | int max_socket = 0; |
| 2048 | BOOL select_failed = FALSE; |
| 2049 | fd_set select_listen; |
| 2050 | |
| 2051 | FD_ZERO(&select_listen); |
| 2052 | for (int sk = 0; sk < listen_socket_count; sk++) |
| 2053 | { |
| 2054 | FD_SET(listen_sockets[sk], &select_listen); |
| 2055 | if (listen_sockets[sk] > max_socket) max_socket = listen_sockets[sk]; |
| 2056 | } |
| 2057 | |
| 2058 | DEBUG(D_any) debug_printf("Listening...\n"); |
| 2059 | |
| 2060 | /* In rare cases we may have had a SIGCHLD signal in the time between |
| 2061 | setting the handler (below) and getting back here. If so, pretend that the |
| 2062 | select() was interrupted so that we reap the child. This might still leave |
| 2063 | a small window when a SIGCHLD could get lost. However, since we use SIGCHLD |
| 2064 | only to do the reaping more quickly, it shouldn't result in anything other |
| 2065 | than a delay until something else causes a wake-up. */ |
| 2066 | |
| 2067 | if (sigchld_seen) |
| 2068 | { |
| 2069 | lcount = -1; |
| 2070 | errno = EINTR; |
| 2071 | } |
| 2072 | else |
| 2073 | lcount = select(max_socket + 1, (SELECT_ARG2_TYPE *)&select_listen, |
| 2074 | NULL, NULL, NULL); |
| 2075 | |
| 2076 | if (lcount < 0) |
| 2077 | { |
| 2078 | select_failed = TRUE; |
| 2079 | lcount = 1; |
| 2080 | } |
| 2081 | |
| 2082 | /* Clean up any subprocesses that may have terminated. We need to do this |
| 2083 | here so that smtp_accept_max_per_host works when a connection to that host |
| 2084 | has completed, and we are about to accept a new one. When this code was |
| 2085 | later in the sequence, a new connection could be rejected, even though an |
| 2086 | old one had just finished. Preserve the errno from any select() failure for |
| 2087 | the use of the common select/accept error processing below. */ |
| 2088 | |
| 2089 | select_errno = errno; |
| 2090 | handle_ending_processes(); |
| 2091 | errno = select_errno; |
| 2092 | |
| 2093 | #ifndef DISABLE_TLS |
| 2094 | /* Create or rotate any required keys */ |
| 2095 | tls_daemon_init(); |
| 2096 | #endif |
| 2097 | |
| 2098 | /* Loop for all the sockets that are currently ready to go. If select |
| 2099 | actually failed, we have set the count to 1 and select_failed=TRUE, so as |
| 2100 | to use the common error code for select/accept below. */ |
| 2101 | |
| 2102 | while (lcount-- > 0) |
| 2103 | { |
| 2104 | int accept_socket = -1; |
| 2105 | |
| 2106 | if (!select_failed) |
| 2107 | for (int sk = 0; sk < listen_socket_count; sk++) |
| 2108 | if (FD_ISSET(listen_sockets[sk], &select_listen)) |
| 2109 | { |
| 2110 | len = sizeof(accepted); |
| 2111 | accept_socket = accept(listen_sockets[sk], |
| 2112 | (struct sockaddr *)&accepted, &len); |
| 2113 | FD_CLR(listen_sockets[sk], &select_listen); |
| 2114 | break; |
| 2115 | } |
| 2116 | |
| 2117 | /* If select or accept has failed and this was not caused by an |
| 2118 | interruption, log the incident and try again. With asymmetric TCP/IP |
| 2119 | routing errors such as "No route to network" have been seen here. Also |
| 2120 | "connection reset by peer" has been seen. These cannot be classed as |
| 2121 | disastrous errors, but they could fill up a lot of log. The code in smail |
| 2122 | crashes the daemon after 10 successive failures of accept, on the grounds |
| 2123 | that some OS fail continuously. Exim originally followed suit, but this |
| 2124 | appears to have caused problems. Now it just keeps going, but instead of |
| 2125 | logging each error, it batches them up when they are continuous. */ |
| 2126 | |
| 2127 | if (accept_socket < 0 && errno != EINTR) |
| 2128 | { |
| 2129 | if (accept_retry_count == 0) |
| 2130 | { |
| 2131 | accept_retry_errno = errno; |
| 2132 | accept_retry_select_failed = select_failed; |
| 2133 | } |
| 2134 | else |
| 2135 | { |
| 2136 | if (errno != accept_retry_errno || |
| 2137 | select_failed != accept_retry_select_failed || |
| 2138 | accept_retry_count >= 50) |
| 2139 | { |
| 2140 | log_write(0, LOG_MAIN | ((accept_retry_count >= 50)? LOG_PANIC : 0), |
| 2141 | "%d %s() failure%s: %s", |
| 2142 | accept_retry_count, |
| 2143 | accept_retry_select_failed? "select" : "accept", |
| 2144 | (accept_retry_count == 1)? "" : "s", |
| 2145 | strerror(accept_retry_errno)); |
| 2146 | log_close_all(); |
| 2147 | accept_retry_count = 0; |
| 2148 | accept_retry_errno = errno; |
| 2149 | accept_retry_select_failed = select_failed; |
| 2150 | } |
| 2151 | } |
| 2152 | accept_retry_count++; |
| 2153 | } |
| 2154 | |
| 2155 | else |
| 2156 | { |
| 2157 | if (accept_retry_count > 0) |
| 2158 | { |
| 2159 | log_write(0, LOG_MAIN, "%d %s() failure%s: %s", |
| 2160 | accept_retry_count, |
| 2161 | accept_retry_select_failed? "select" : "accept", |
| 2162 | (accept_retry_count == 1)? "" : "s", |
| 2163 | strerror(accept_retry_errno)); |
| 2164 | log_close_all(); |
| 2165 | accept_retry_count = 0; |
| 2166 | } |
| 2167 | } |
| 2168 | |
| 2169 | /* If select/accept succeeded, deal with the connection. */ |
| 2170 | |
| 2171 | if (accept_socket >= 0) |
| 2172 | { |
| 2173 | if (inetd_wait_timeout) |
| 2174 | last_connection_time = time(NULL); |
| 2175 | handle_smtp_call(listen_sockets, listen_socket_count, accept_socket, |
| 2176 | (struct sockaddr *)&accepted); |
| 2177 | } |
| 2178 | } |
| 2179 | } |
| 2180 | |
| 2181 | /* If not listening, then just sleep for the queue interval. If we woke |
| 2182 | up early the last time for some other signal, it won't matter because |
| 2183 | the alarm signal will wake at the right time. This code originally used |
| 2184 | sleep() but it turns out that on the FreeBSD system, sleep() is not inter- |
| 2185 | rupted by signals, so it wasn't waking up for SIGALRM or SIGCHLD. Luckily |
| 2186 | select() can be used as an interruptible sleep() on all versions of Unix. */ |
| 2187 | |
| 2188 | else |
| 2189 | { |
| 2190 | struct timeval tv; |
| 2191 | tv.tv_sec = queue_interval; |
| 2192 | tv.tv_usec = 0; |
| 2193 | select(0, NULL, NULL, NULL, &tv); |
| 2194 | handle_ending_processes(); |
| 2195 | } |
| 2196 | |
| 2197 | /* Re-enable the SIGCHLD handler if it has been run. It can't do it |
| 2198 | for itself, because it isn't doing the waiting itself. */ |
| 2199 | |
| 2200 | if (sigchld_seen) |
| 2201 | { |
| 2202 | sigchld_seen = FALSE; |
| 2203 | os_non_restarting_signal(SIGCHLD, main_sigchld_handler); |
| 2204 | } |
| 2205 | |
| 2206 | /* Handle being woken by SIGHUP. We know at this point that the result |
| 2207 | of accept() has been dealt with, so we can re-exec exim safely, first |
| 2208 | closing the listening sockets so that they can be reused. Cancel any pending |
| 2209 | alarm in case it is just about to go off, and set SIGHUP to be ignored so |
| 2210 | that another HUP in quick succession doesn't clobber the new daemon before it |
| 2211 | gets going. All log files get closed by the close-on-exec flag; however, if |
| 2212 | the exec fails, we need to close the logs. */ |
| 2213 | |
| 2214 | if (sighup_seen) |
| 2215 | { |
| 2216 | log_write(0, LOG_MAIN, "pid %d: SIGHUP received: re-exec daemon", |
| 2217 | getpid()); |
| 2218 | for (int sk = 0; sk < listen_socket_count; sk++) |
| 2219 | (void)close(listen_sockets[sk]); |
| 2220 | ALARM_CLR(0); |
| 2221 | signal(SIGHUP, SIG_IGN); |
| 2222 | sighup_argv[0] = exim_path; |
| 2223 | exim_nullstd(); |
| 2224 | execv(CS exim_path, (char *const *)sighup_argv); |
| 2225 | log_write(0, LOG_MAIN|LOG_PANIC_DIE, "pid %d: exec of %s failed: %s", |
| 2226 | getpid(), exim_path, strerror(errno)); |
| 2227 | log_close_all(); |
| 2228 | } |
| 2229 | |
| 2230 | } /* End of main loop */ |
| 2231 | |
| 2232 | /* Control never reaches here */ |
| 2233 | } |
| 2234 | |
| 2235 | /* vi: aw ai sw=2 |
| 2236 | */ |
| 2237 | /* End of exim_daemon.c */ |