429b6352c9badc69c6b9ed4ed01102179c9236ab
[exim.git] / src / src / host.c
1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
4
5 /* Copyright (c) University of Cambridge 1995 - 2015 */
6 /* See the file NOTICE for conditions of use and distribution. */
7
8 /* Functions for finding hosts, either by gethostbyname(), gethostbyaddr(), or
9 directly via the DNS. When IPv6 is supported, getipnodebyname() and
10 getipnodebyaddr() may be used instead of gethostbyname() and gethostbyaddr(),
11 if the newer functions are available. This module also contains various other
12 functions concerned with hosts and addresses, and a random number function,
13 used for randomizing hosts with equal MXs but available for use in other parts
14 of Exim. */
15
16
17 #include "exim.h"
18
19
20 /* Static variable for preserving the list of interface addresses in case it is
21 used more than once. */
22
23 static ip_address_item *local_interface_data = NULL;
24
25
26 #ifdef USE_INET_NTOA_FIX
27 /*************************************************
28 * Replacement for broken inet_ntoa() *
29 *************************************************/
30
31 /* On IRIX systems, gcc uses a different structure passing convention to the
32 native libraries. This causes inet_ntoa() to always yield 0.0.0.0 or
33 255.255.255.255. To get round this, we provide a private version of the
34 function here. It is used only if USE_INET_NTOA_FIX is set, which should happen
35 only when gcc is in use on an IRIX system. Code send to me by J.T. Breitner,
36 with these comments:
37
38 code by Stuart Levy
39 as seen in comp.sys.sgi.admin
40
41 August 2005: Apparently this is also needed for AIX systems; USE_INET_NTOA_FIX
42 should now be set for them as well.
43
44 Arguments: sa an in_addr structure
45 Returns: pointer to static text string
46 */
47
48 char *
49 inet_ntoa(struct in_addr sa)
50 {
51 static uschar addr[20];
52 sprintf(addr, "%d.%d.%d.%d",
53 (US &sa.s_addr)[0],
54 (US &sa.s_addr)[1],
55 (US &sa.s_addr)[2],
56 (US &sa.s_addr)[3]);
57 return addr;
58 }
59 #endif
60
61
62
63 /*************************************************
64 * Random number generator *
65 *************************************************/
66
67 /* This is a simple pseudo-random number generator. It does not have to be
68 very good for the uses to which it is put. When running the regression tests,
69 start with a fixed seed.
70
71 If you need better, see vaguely_random_number() which is potentially stronger,
72 if a crypto library is available, but might end up just calling this instead.
73
74 Arguments:
75 limit: one more than the largest number required
76
77 Returns: a pseudo-random number in the range 0 to limit-1
78 */
79
80 int
81 random_number(int limit)
82 {
83 if (limit < 1)
84 return 0;
85 if (random_seed == 0)
86 {
87 if (running_in_test_harness) random_seed = 42; else
88 {
89 int p = (int)getpid();
90 random_seed = (int)time(NULL) ^ ((p << 16) | p);
91 }
92 }
93 random_seed = 1103515245 * random_seed + 12345;
94 return (unsigned int)(random_seed >> 16) % limit;
95 }
96
97 /*************************************************
98 * Wrappers for logging lookup times *
99 *************************************************/
100
101 /* When the 'slow_lookup_log' variable is enabled, these wrappers will
102 write to the log file all (potential) dns lookups that take more than
103 slow_lookup_log milliseconds
104 */
105
106 static void
107 log_long_lookup(const uschar * type, const uschar * data, unsigned long msec)
108 {
109 log_write(0, LOG_MAIN, "Long %s lookup for '%s': %lu msec",
110 type, data, msec);
111 }
112
113
114 /* returns the current system epoch time in milliseconds. */
115 static unsigned long
116 get_time_in_ms()
117 {
118 struct timeval tmp_time;
119 unsigned long seconds, microseconds;
120
121 gettimeofday(&tmp_time, NULL);
122 seconds = (unsigned long) tmp_time.tv_sec;
123 microseconds = (unsigned long) tmp_time.tv_usec;
124 return seconds*1000 + microseconds/1000;
125 }
126
127
128 static int
129 dns_lookup_timerwrap(dns_answer *dnsa, const uschar *name, int type,
130 const uschar **fully_qualified_name)
131 {
132 int retval;
133 unsigned long time_msec;
134
135 if (!slow_lookup_log)
136 return dns_lookup(dnsa, name, type, fully_qualified_name);
137
138 time_msec = get_time_in_ms();
139 retval = dns_lookup(dnsa, name, type, fully_qualified_name);
140 if ((time_msec = get_time_in_ms() - time_msec) > slow_lookup_log)
141 log_long_lookup(US"name", name, time_msec);
142 return retval;
143 }
144
145
146 /*************************************************
147 * Replace gethostbyname() when testing *
148 *************************************************/
149
150 /* This function is called instead of gethostbyname(), gethostbyname2(), or
151 getipnodebyname() when running in the test harness. . It also
152 recognizes an unqualified "localhost" and forces it to the appropriate loopback
153 address. IP addresses are treated as literals. For other names, it uses the DNS
154 to find the host name. In the test harness, this means it will access only the
155 fake DNS resolver.
156
157 Arguments:
158 name the host name or a textual IP address
159 af AF_INET or AF_INET6
160 error_num where to put an error code:
161 HOST_NOT_FOUND/TRY_AGAIN/NO_RECOVERY/NO_DATA
162
163 Returns: a hostent structure or NULL for an error
164 */
165
166 static struct hostent *
167 host_fake_gethostbyname(const uschar *name, int af, int *error_num)
168 {
169 #if HAVE_IPV6
170 int alen = (af == AF_INET)? sizeof(struct in_addr):sizeof(struct in6_addr);
171 #else
172 int alen = sizeof(struct in_addr);
173 #endif
174
175 int ipa;
176 const uschar *lname = name;
177 uschar *adds;
178 uschar **alist;
179 struct hostent *yield;
180 dns_answer dnsa;
181 dns_scan dnss;
182 dns_record *rr;
183
184 DEBUG(D_host_lookup)
185 debug_printf("using host_fake_gethostbyname for %s (%s)\n", name,
186 (af == AF_INET)? "IPv4" : "IPv6");
187
188 /* Handle unqualified "localhost" */
189
190 if (Ustrcmp(name, "localhost") == 0)
191 lname = (af == AF_INET)? US"127.0.0.1" : US"::1";
192
193 /* Handle a literal IP address */
194
195 ipa = string_is_ip_address(lname, NULL);
196 if (ipa != 0)
197 {
198 if ((ipa == 4 && af == AF_INET) ||
199 (ipa == 6 && af == AF_INET6))
200 {
201 int i, n;
202 int x[4];
203 yield = store_get(sizeof(struct hostent));
204 alist = store_get(2 * sizeof(char *));
205 adds = store_get(alen);
206 yield->h_name = CS name;
207 yield->h_aliases = NULL;
208 yield->h_addrtype = af;
209 yield->h_length = alen;
210 yield->h_addr_list = CSS alist;
211 *alist++ = adds;
212 n = host_aton(lname, x);
213 for (i = 0; i < n; i++)
214 {
215 int y = x[i];
216 *adds++ = (y >> 24) & 255;
217 *adds++ = (y >> 16) & 255;
218 *adds++ = (y >> 8) & 255;
219 *adds++ = y & 255;
220 }
221 *alist = NULL;
222 }
223
224 /* Wrong kind of literal address */
225
226 else
227 {
228 *error_num = HOST_NOT_FOUND;
229 return NULL;
230 }
231 }
232
233 /* Handle a host name */
234
235 else
236 {
237 int type = (af == AF_INET)? T_A:T_AAAA;
238 int rc = dns_lookup_timerwrap(&dnsa, lname, type, NULL);
239 int count = 0;
240
241 lookup_dnssec_authenticated = NULL;
242
243 switch(rc)
244 {
245 case DNS_SUCCEED: break;
246 case DNS_NOMATCH: *error_num = HOST_NOT_FOUND; return NULL;
247 case DNS_NODATA: *error_num = NO_DATA; return NULL;
248 case DNS_AGAIN: *error_num = TRY_AGAIN; return NULL;
249 default:
250 case DNS_FAIL: *error_num = NO_RECOVERY; return NULL;
251 }
252
253 for (rr = dns_next_rr(&dnsa, &dnss, RESET_ANSWERS);
254 rr;
255 rr = dns_next_rr(&dnsa, &dnss, RESET_NEXT))
256 if (rr->type == type)
257 count++;
258
259 yield = store_get(sizeof(struct hostent));
260 alist = store_get((count + 1) * sizeof(char **));
261 adds = store_get(count *alen);
262
263 yield->h_name = CS name;
264 yield->h_aliases = NULL;
265 yield->h_addrtype = af;
266 yield->h_length = alen;
267 yield->h_addr_list = CSS alist;
268
269 for (rr = dns_next_rr(&dnsa, &dnss, RESET_ANSWERS);
270 rr;
271 rr = dns_next_rr(&dnsa, &dnss, RESET_NEXT))
272 {
273 int i, n;
274 int x[4];
275 dns_address *da;
276 if (rr->type != type) continue;
277 if (!(da = dns_address_from_rr(&dnsa, rr))) break;
278 *alist++ = adds;
279 n = host_aton(da->address, x);
280 for (i = 0; i < n; i++)
281 {
282 int y = x[i];
283 *adds++ = (y >> 24) & 255;
284 *adds++ = (y >> 16) & 255;
285 *adds++ = (y >> 8) & 255;
286 *adds++ = y & 255;
287 }
288 }
289 *alist = NULL;
290 }
291
292 return yield;
293 }
294
295
296
297 /*************************************************
298 * Build chain of host items from list *
299 *************************************************/
300
301 /* This function builds a chain of host items from a textual list of host
302 names. It does not do any lookups. If randomize is true, the chain is build in
303 a randomized order. There may be multiple groups of independently randomized
304 hosts; they are delimited by a host name consisting of just "+".
305
306 Arguments:
307 anchor anchor for the chain
308 list text list
309 randomize TRUE for randomizing
310
311 Returns: nothing
312 */
313
314 void
315 host_build_hostlist(host_item **anchor, const uschar *list, BOOL randomize)
316 {
317 int sep = 0;
318 int fake_mx = MX_NONE; /* This value is actually -1 */
319 uschar *name;
320
321 if (list == NULL) return;
322 if (randomize) fake_mx--; /* Start at -2 for randomizing */
323
324 *anchor = NULL;
325
326 while ((name = string_nextinlist(&list, &sep, NULL, 0)) != NULL)
327 {
328 host_item *h;
329
330 if (name[0] == '+' && name[1] == 0) /* "+" delimits a randomized group */
331 { /* ignore if not randomizing */
332 if (randomize) fake_mx--;
333 continue;
334 }
335
336 h = store_get(sizeof(host_item));
337 h->name = name;
338 h->address = NULL;
339 h->port = PORT_NONE;
340 h->mx = fake_mx;
341 h->sort_key = randomize? (-fake_mx)*1000 + random_number(1000) : 0;
342 h->status = hstatus_unknown;
343 h->why = hwhy_unknown;
344 h->last_try = 0;
345
346 if (*anchor == NULL)
347 {
348 h->next = NULL;
349 *anchor = h;
350 }
351 else
352 {
353 host_item *hh = *anchor;
354 if (h->sort_key < hh->sort_key)
355 {
356 h->next = hh;
357 *anchor = h;
358 }
359 else
360 {
361 while (hh->next != NULL && h->sort_key >= (hh->next)->sort_key)
362 hh = hh->next;
363 h->next = hh->next;
364 hh->next = h;
365 }
366 }
367 }
368 }
369
370
371
372
373
374 /*************************************************
375 * Extract port from address string *
376 *************************************************/
377
378 /* In the spool file, and in the -oMa and -oMi options, a host plus port is
379 given as an IP address followed by a dot and a port number. This function
380 decodes this.
381
382 An alternative format for the -oMa and -oMi options is [ip address]:port which
383 is what Exim 4 uses for output, because it seems to becoming commonly used,
384 whereas the dot form confuses some programs/people. So we recognize that form
385 too.
386
387 Argument:
388 address points to the string; if there is a port, the '.' in the string
389 is overwritten with zero to terminate the address; if the string
390 is in the [xxx]:ppp format, the address is shifted left and the
391 brackets are removed
392
393 Returns: 0 if there is no port, else the port number. If there's a syntax
394 error, leave the incoming address alone, and return 0.
395 */
396
397 int
398 host_address_extract_port(uschar *address)
399 {
400 int port = 0;
401 uschar *endptr;
402
403 /* Handle the "bracketed with colon on the end" format */
404
405 if (*address == '[')
406 {
407 uschar *rb = address + 1;
408 while (*rb != 0 && *rb != ']') rb++;
409 if (*rb++ == 0) return 0; /* Missing ]; leave invalid address */
410 if (*rb == ':')
411 {
412 port = Ustrtol(rb + 1, &endptr, 10);
413 if (*endptr != 0) return 0; /* Invalid port; leave invalid address */
414 }
415 else if (*rb != 0) return 0; /* Bad syntax; leave invalid address */
416 memmove(address, address + 1, rb - address - 2);
417 rb[-2] = 0;
418 }
419
420 /* Handle the "dot on the end" format */
421
422 else
423 {
424 int skip = -3; /* Skip 3 dots in IPv4 addresses */
425 address--;
426 while (*(++address) != 0)
427 {
428 int ch = *address;
429 if (ch == ':') skip = 0; /* Skip 0 dots in IPv6 addresses */
430 else if (ch == '.' && skip++ >= 0) break;
431 }
432 if (*address == 0) return 0;
433 port = Ustrtol(address + 1, &endptr, 10);
434 if (*endptr != 0) return 0; /* Invalid port; leave invalid address */
435 *address = 0;
436 }
437
438 return port;
439 }
440
441
442 /*************************************************
443 * Get port from a host item's name *
444 *************************************************/
445
446 /* This function is called when finding the IP address for a host that is in a
447 list of hosts explicitly configured, such as in the manualroute router, or in a
448 fallback hosts list. We see if there is a port specification at the end of the
449 host name, and if so, remove it. A minimum length of 3 is required for the
450 original name; nothing shorter is recognized as having a port.
451
452 We test for a name ending with a sequence of digits; if preceded by colon we
453 have a port if the character before the colon is ] and the name starts with [
454 or if there are no other colons in the name (i.e. it's not an IPv6 address).
455
456 Arguments: pointer to the host item
457 Returns: a port number or PORT_NONE
458 */
459
460 int
461 host_item_get_port(host_item *h)
462 {
463 const uschar *p;
464 int port, x;
465 int len = Ustrlen(h->name);
466
467 if (len < 3 || (p = h->name + len - 1, !isdigit(*p))) return PORT_NONE;
468
469 /* Extract potential port number */
470
471 port = *p-- - '0';
472 x = 10;
473
474 while (p > h->name + 1 && isdigit(*p))
475 {
476 port += (*p-- - '0') * x;
477 x *= 10;
478 }
479
480 /* The smallest value of p at this point is h->name + 1. */
481
482 if (*p != ':') return PORT_NONE;
483
484 if (p[-1] == ']' && h->name[0] == '[')
485 h->name = string_copyn(h->name + 1, p - h->name - 2);
486 else if (Ustrchr(h->name, ':') == p)
487 h->name = string_copyn(h->name, p - h->name);
488 else return PORT_NONE;
489
490 DEBUG(D_route|D_host_lookup) debug_printf("host=%s port=%d\n", h->name, port);
491 return port;
492 }
493
494
495
496 #ifndef STAND_ALONE /* Omit when standalone testing */
497
498 /*************************************************
499 * Build sender_fullhost and sender_rcvhost *
500 *************************************************/
501
502 /* This function is called when sender_host_name and/or sender_helo_name
503 have been set. Or might have been set - for a local message read off the spool
504 they won't be. In that case, do nothing. Otherwise, set up the fullhost string
505 as follows:
506
507 (a) No sender_host_name or sender_helo_name: "[ip address]"
508 (b) Just sender_host_name: "host_name [ip address]"
509 (c) Just sender_helo_name: "(helo_name) [ip address]" unless helo is IP
510 in which case: "[ip address}"
511 (d) The two are identical: "host_name [ip address]" includes helo = IP
512 (e) The two are different: "host_name (helo_name) [ip address]"
513
514 If log_incoming_port is set, the sending host's port number is added to the IP
515 address.
516
517 This function also builds sender_rcvhost for use in Received: lines, whose
518 syntax is a bit different. This value also includes the RFC 1413 identity.
519 There wouldn't be two different variables if I had got all this right in the
520 first place.
521
522 Because this data may survive over more than one incoming SMTP message, it has
523 to be in permanent store.
524
525 Arguments: none
526 Returns: nothing
527 */
528
529 void
530 host_build_sender_fullhost(void)
531 {
532 BOOL show_helo = TRUE;
533 uschar *address;
534 int len;
535 int old_pool = store_pool;
536
537 if (sender_host_address == NULL) return;
538
539 store_pool = POOL_PERM;
540
541 /* Set up address, with or without the port. After discussion, it seems that
542 the only format that doesn't cause trouble is [aaaa]:pppp. However, we can't
543 use this directly as the first item for Received: because it ain't an RFC 2822
544 domain. Sigh. */
545
546 address = string_sprintf("[%s]:%d", sender_host_address, sender_host_port);
547 if (!LOGGING(incoming_port) || sender_host_port <= 0)
548 *(Ustrrchr(address, ':')) = 0;
549
550 /* If there's no EHLO/HELO data, we can't show it. */
551
552 if (sender_helo_name == NULL) show_helo = FALSE;
553
554 /* If HELO/EHLO was followed by an IP literal, it's messy because of two
555 features of IPv6. Firstly, there's the "IPv6:" prefix (Exim is liberal and
556 doesn't require this, for historical reasons). Secondly, IPv6 addresses may not
557 be given in canonical form, so we have to canonicize them before comparing. As
558 it happens, the code works for both IPv4 and IPv6. */
559
560 else if (sender_helo_name[0] == '[' &&
561 sender_helo_name[(len=Ustrlen(sender_helo_name))-1] == ']')
562 {
563 int offset = 1;
564 uschar *helo_ip;
565
566 if (strncmpic(sender_helo_name + 1, US"IPv6:", 5) == 0) offset += 5;
567 if (strncmpic(sender_helo_name + 1, US"IPv4:", 5) == 0) offset += 5;
568
569 helo_ip = string_copyn(sender_helo_name + offset, len - offset - 1);
570
571 if (string_is_ip_address(helo_ip, NULL) != 0)
572 {
573 int x[4], y[4];
574 int sizex, sizey;
575 uschar ipx[48], ipy[48]; /* large enough for full IPv6 */
576
577 sizex = host_aton(helo_ip, x);
578 sizey = host_aton(sender_host_address, y);
579
580 (void)host_nmtoa(sizex, x, -1, ipx, ':');
581 (void)host_nmtoa(sizey, y, -1, ipy, ':');
582
583 if (strcmpic(ipx, ipy) == 0) show_helo = FALSE;
584 }
585 }
586
587 /* Host name is not verified */
588
589 if (sender_host_name == NULL)
590 {
591 uschar *portptr = Ustrstr(address, "]:");
592 int size = 0;
593 int ptr = 0;
594 int adlen; /* Sun compiler doesn't like ++ in initializers */
595
596 adlen = (portptr == NULL)? Ustrlen(address) : (++portptr - address);
597 sender_fullhost = (sender_helo_name == NULL)? address :
598 string_sprintf("(%s) %s", sender_helo_name, address);
599
600 sender_rcvhost = string_cat(NULL, &size, &ptr, address, adlen);
601
602 if (sender_ident != NULL || show_helo || portptr != NULL)
603 {
604 int firstptr;
605 sender_rcvhost = string_cat(sender_rcvhost, &size, &ptr, US" (", 2);
606 firstptr = ptr;
607
608 if (portptr != NULL)
609 sender_rcvhost = string_append(sender_rcvhost, &size, &ptr, 2, US"port=",
610 portptr + 1);
611
612 if (show_helo)
613 sender_rcvhost = string_append(sender_rcvhost, &size, &ptr, 2,
614 (firstptr == ptr)? US"helo=" : US" helo=", sender_helo_name);
615
616 if (sender_ident != NULL)
617 sender_rcvhost = string_append(sender_rcvhost, &size, &ptr, 2,
618 (firstptr == ptr)? US"ident=" : US" ident=", sender_ident);
619
620 sender_rcvhost = string_cat(sender_rcvhost, &size, &ptr, US")", 1);
621 }
622
623 sender_rcvhost[ptr] = 0; /* string_cat() always leaves room */
624
625 /* Release store, because string_cat allocated a minimum of 100 bytes that
626 are rarely completely used. */
627
628 store_reset(sender_rcvhost + ptr + 1);
629 }
630
631 /* Host name is known and verified. Unless we've already found that the HELO
632 data matches the IP address, compare it with the name. */
633
634 else
635 {
636 if (show_helo && strcmpic(sender_host_name, sender_helo_name) == 0)
637 show_helo = FALSE;
638
639 if (show_helo)
640 {
641 sender_fullhost = string_sprintf("%s (%s) %s", sender_host_name,
642 sender_helo_name, address);
643 sender_rcvhost = (sender_ident == NULL)?
644 string_sprintf("%s (%s helo=%s)", sender_host_name,
645 address, sender_helo_name) :
646 string_sprintf("%s\n\t(%s helo=%s ident=%s)", sender_host_name,
647 address, sender_helo_name, sender_ident);
648 }
649 else
650 {
651 sender_fullhost = string_sprintf("%s %s", sender_host_name, address);
652 sender_rcvhost = (sender_ident == NULL)?
653 string_sprintf("%s (%s)", sender_host_name, address) :
654 string_sprintf("%s (%s ident=%s)", sender_host_name, address,
655 sender_ident);
656 }
657 }
658
659 store_pool = old_pool;
660
661 DEBUG(D_host_lookup) debug_printf("sender_fullhost = %s\n", sender_fullhost);
662 DEBUG(D_host_lookup) debug_printf("sender_rcvhost = %s\n", sender_rcvhost);
663 }
664
665
666
667 /*************************************************
668 * Build host+ident message *
669 *************************************************/
670
671 /* Used when logging rejections and various ACL and SMTP incidents. The text
672 return depends on whether sender_fullhost and sender_ident are set or not:
673
674 no ident, no host => U=unknown
675 no ident, host set => H=sender_fullhost
676 ident set, no host => U=ident
677 ident set, host set => H=sender_fullhost U=ident
678
679 Arguments:
680 useflag TRUE if first item to be flagged (H= or U=); if there are two
681 items, the second is always flagged
682
683 Returns: pointer to a string in big_buffer
684 */
685
686 uschar *
687 host_and_ident(BOOL useflag)
688 {
689 if (sender_fullhost == NULL)
690 {
691 (void)string_format(big_buffer, big_buffer_size, "%s%s", useflag? "U=" : "",
692 (sender_ident == NULL)? US"unknown" : sender_ident);
693 }
694 else
695 {
696 uschar *flag = useflag? US"H=" : US"";
697 uschar *iface = US"";
698 if (LOGGING(incoming_interface) && interface_address != NULL)
699 iface = string_sprintf(" I=[%s]:%d", interface_address, interface_port);
700 if (sender_ident == NULL)
701 (void)string_format(big_buffer, big_buffer_size, "%s%s%s",
702 flag, sender_fullhost, iface);
703 else
704 (void)string_format(big_buffer, big_buffer_size, "%s%s%s U=%s",
705 flag, sender_fullhost, iface, sender_ident);
706 }
707 return big_buffer;
708 }
709
710 #endif /* STAND_ALONE */
711
712
713
714
715 /*************************************************
716 * Build list of local interfaces *
717 *************************************************/
718
719 /* This function interprets the contents of the local_interfaces or
720 extra_local_interfaces options, and creates an ip_address_item block for each
721 item on the list. There is no special interpretation of any IP addresses; in
722 particular, 0.0.0.0 and ::0 are returned without modification. If any address
723 includes a port, it is set in the block. Otherwise the port value is set to
724 zero.
725
726 Arguments:
727 list the list
728 name the name of the option being expanded
729
730 Returns: a chain of ip_address_items, each containing to a textual
731 version of an IP address, and a port number (host order) or
732 zero if no port was given with the address
733 */
734
735 ip_address_item *
736 host_build_ifacelist(const uschar *list, uschar *name)
737 {
738 int sep = 0;
739 uschar *s;
740 uschar buffer[64];
741 ip_address_item *yield = NULL;
742 ip_address_item *last = NULL;
743 ip_address_item *next;
744
745 while ((s = string_nextinlist(&list, &sep, buffer, sizeof(buffer))) != NULL)
746 {
747 int ipv;
748 int port = host_address_extract_port(s); /* Leaves just the IP address */
749 if ((ipv = string_is_ip_address(s, NULL)) == 0)
750 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "Malformed IP address \"%s\" in %s",
751 s, name);
752
753 /* Skip IPv6 addresses if IPv6 is disabled. */
754
755 if (disable_ipv6 && ipv == 6) continue;
756
757 /* This use of strcpy() is OK because we have checked that s is a valid IP
758 address above. The field in the ip_address_item is large enough to hold an
759 IPv6 address. */
760
761 next = store_get(sizeof(ip_address_item));
762 next->next = NULL;
763 Ustrcpy(next->address, s);
764 next->port = port;
765 next->v6_include_v4 = FALSE;
766
767 if (yield == NULL) yield = last = next; else
768 {
769 last->next = next;
770 last = next;
771 }
772 }
773
774 return yield;
775 }
776
777
778
779
780
781 /*************************************************
782 * Find addresses on local interfaces *
783 *************************************************/
784
785 /* This function finds the addresses of local IP interfaces. These are used
786 when testing for routing to the local host. As the function may be called more
787 than once, the list is preserved in permanent store, pointed to by a static
788 variable, to save doing the work more than once per process.
789
790 The generic list of interfaces is obtained by calling host_build_ifacelist()
791 for local_interfaces and extra_local_interfaces. This list scanned to remove
792 duplicates (which may exist with different ports - not relevant here). If
793 either of the wildcard IP addresses (0.0.0.0 and ::0) are encountered, they are
794 replaced by the appropriate (IPv4 or IPv6) list of actual local interfaces,
795 obtained from os_find_running_interfaces().
796
797 Arguments: none
798 Returns: a chain of ip_address_items, each containing to a textual
799 version of an IP address; the port numbers are not relevant
800 */
801
802
803 /* First, a local subfunction to add an interface to a list in permanent store,
804 but only if there isn't a previous copy of that address on the list. */
805
806 static ip_address_item *
807 add_unique_interface(ip_address_item *list, ip_address_item *ipa)
808 {
809 ip_address_item *ipa2;
810 for (ipa2 = list; ipa2 != NULL; ipa2 = ipa2->next)
811 if (Ustrcmp(ipa2->address, ipa->address) == 0) return list;
812 ipa2 = store_get_perm(sizeof(ip_address_item));
813 *ipa2 = *ipa;
814 ipa2->next = list;
815 return ipa2;
816 }
817
818
819 /* This is the globally visible function */
820
821 ip_address_item *
822 host_find_interfaces(void)
823 {
824 ip_address_item *running_interfaces = NULL;
825
826 if (local_interface_data == NULL)
827 {
828 void *reset_item = store_get(0);
829 ip_address_item *dlist = host_build_ifacelist(CUS local_interfaces,
830 US"local_interfaces");
831 ip_address_item *xlist = host_build_ifacelist(CUS extra_local_interfaces,
832 US"extra_local_interfaces");
833 ip_address_item *ipa;
834
835 if (dlist == NULL) dlist = xlist; else
836 {
837 for (ipa = dlist; ipa->next != NULL; ipa = ipa->next);
838 ipa->next = xlist;
839 }
840
841 for (ipa = dlist; ipa != NULL; ipa = ipa->next)
842 {
843 if (Ustrcmp(ipa->address, "0.0.0.0") == 0 ||
844 Ustrcmp(ipa->address, "::0") == 0)
845 {
846 ip_address_item *ipa2;
847 BOOL ipv6 = ipa->address[0] == ':';
848 if (running_interfaces == NULL)
849 running_interfaces = os_find_running_interfaces();
850 for (ipa2 = running_interfaces; ipa2 != NULL; ipa2 = ipa2->next)
851 {
852 if ((Ustrchr(ipa2->address, ':') != NULL) == ipv6)
853 local_interface_data = add_unique_interface(local_interface_data,
854 ipa2);
855 }
856 }
857 else
858 {
859 local_interface_data = add_unique_interface(local_interface_data, ipa);
860 DEBUG(D_interface)
861 {
862 debug_printf("Configured local interface: address=%s", ipa->address);
863 if (ipa->port != 0) debug_printf(" port=%d", ipa->port);
864 debug_printf("\n");
865 }
866 }
867 }
868 store_reset(reset_item);
869 }
870
871 return local_interface_data;
872 }
873
874
875
876
877
878 /*************************************************
879 * Convert network IP address to text *
880 *************************************************/
881
882 /* Given an IPv4 or IPv6 address in binary, convert it to a text
883 string and return the result in a piece of new store. The address can
884 either be given directly, or passed over in a sockaddr structure. Note
885 that this isn't the converse of host_aton() because of byte ordering
886 differences. See host_nmtoa() below.
887
888 Arguments:
889 type if < 0 then arg points to a sockaddr, else
890 either AF_INET or AF_INET6
891 arg points to a sockaddr if type is < 0, or
892 points to an IPv4 address (32 bits), or
893 points to an IPv6 address (128 bits),
894 in both cases, in network byte order
895 buffer if NULL, the result is returned in gotten store;
896 else points to a buffer to hold the answer
897 portptr points to where to put the port number, if non NULL; only
898 used when type < 0
899
900 Returns: pointer to character string
901 */
902
903 uschar *
904 host_ntoa(int type, const void *arg, uschar *buffer, int *portptr)
905 {
906 uschar *yield;
907
908 /* The new world. It is annoying that we have to fish out the address from
909 different places in the block, depending on what kind of address it is. It
910 is also a pain that inet_ntop() returns a const uschar *, whereas the IPv4
911 function inet_ntoa() returns just uschar *, and some picky compilers insist
912 on warning if one assigns a const uschar * to a uschar *. Hence the casts. */
913
914 #if HAVE_IPV6
915 uschar addr_buffer[46];
916 if (type < 0)
917 {
918 int family = ((struct sockaddr *)arg)->sa_family;
919 if (family == AF_INET6)
920 {
921 struct sockaddr_in6 *sk = (struct sockaddr_in6 *)arg;
922 yield = (uschar *)inet_ntop(family, &(sk->sin6_addr), CS addr_buffer,
923 sizeof(addr_buffer));
924 if (portptr != NULL) *portptr = ntohs(sk->sin6_port);
925 }
926 else
927 {
928 struct sockaddr_in *sk = (struct sockaddr_in *)arg;
929 yield = (uschar *)inet_ntop(family, &(sk->sin_addr), CS addr_buffer,
930 sizeof(addr_buffer));
931 if (portptr != NULL) *portptr = ntohs(sk->sin_port);
932 }
933 }
934 else
935 {
936 yield = (uschar *)inet_ntop(type, arg, CS addr_buffer, sizeof(addr_buffer));
937 }
938
939 /* If the result is a mapped IPv4 address, show it in V4 format. */
940
941 if (Ustrncmp(yield, "::ffff:", 7) == 0) yield += 7;
942
943 #else /* HAVE_IPV6 */
944
945 /* The old world */
946
947 if (type < 0)
948 {
949 yield = US inet_ntoa(((struct sockaddr_in *)arg)->sin_addr);
950 if (portptr != NULL) *portptr = ntohs(((struct sockaddr_in *)arg)->sin_port);
951 }
952 else
953 yield = US inet_ntoa(*((struct in_addr *)arg));
954 #endif
955
956 /* If there is no buffer, put the string into some new store. */
957
958 if (buffer == NULL) return string_copy(yield);
959
960 /* Callers of this function with a non-NULL buffer must ensure that it is
961 large enough to hold an IPv6 address, namely, at least 46 bytes. That's what
962 makes this use of strcpy() OK. */
963
964 Ustrcpy(buffer, yield);
965 return buffer;
966 }
967
968
969
970
971 /*************************************************
972 * Convert address text to binary *
973 *************************************************/
974
975 /* Given the textual form of an IP address, convert it to binary in an
976 array of ints. IPv4 addresses occupy one int; IPv6 addresses occupy 4 ints.
977 The result has the first byte in the most significant byte of the first int. In
978 other words, the result is not in network byte order, but in host byte order.
979 As a result, this is not the converse of host_ntoa(), which expects network
980 byte order. See host_nmtoa() below.
981
982 Arguments:
983 address points to the textual address, checked for syntax
984 bin points to an array of 4 ints
985
986 Returns: the number of ints used
987 */
988
989 int
990 host_aton(const uschar *address, int *bin)
991 {
992 int x[4];
993 int v4offset = 0;
994
995 /* Handle IPv6 address, which may end with an IPv4 address. It may also end
996 with a "scope", introduced by a percent sign. This code is NOT enclosed in #if
997 HAVE_IPV6 in order that IPv6 addresses are recognized even if IPv6 is not
998 supported. */
999
1000 if (Ustrchr(address, ':') != NULL)
1001 {
1002 const uschar *p = address;
1003 const uschar *component[8];
1004 BOOL ipv4_ends = FALSE;
1005 int ci = 0;
1006 int nulloffset = 0;
1007 int v6count = 8;
1008 int i;
1009
1010 /* If the address starts with a colon, it will start with two colons.
1011 Just lose the first one, which will leave a null first component. */
1012
1013 if (*p == ':') p++;
1014
1015 /* Split the address into components separated by colons. The input address
1016 is supposed to be checked for syntax. There was a case where this was
1017 overlooked; to guard against that happening again, check here and crash if
1018 there are too many components. */
1019
1020 while (*p != 0 && *p != '%')
1021 {
1022 int len = Ustrcspn(p, ":%");
1023 if (len == 0) nulloffset = ci;
1024 if (ci > 7) log_write(0, LOG_MAIN|LOG_PANIC_DIE,
1025 "Internal error: invalid IPv6 address \"%s\" passed to host_aton()",
1026 address);
1027 component[ci++] = p;
1028 p += len;
1029 if (*p == ':') p++;
1030 }
1031
1032 /* If the final component contains a dot, it is a trailing v4 address.
1033 As the syntax is known to be checked, just set up for a trailing
1034 v4 address and restrict the v6 part to 6 components. */
1035
1036 if (Ustrchr(component[ci-1], '.') != NULL)
1037 {
1038 address = component[--ci];
1039 ipv4_ends = TRUE;
1040 v4offset = 3;
1041 v6count = 6;
1042 }
1043
1044 /* If there are fewer than 6 or 8 components, we have to insert some
1045 more empty ones in the middle. */
1046
1047 if (ci < v6count)
1048 {
1049 int insert_count = v6count - ci;
1050 for (i = v6count-1; i > nulloffset + insert_count; i--)
1051 component[i] = component[i - insert_count];
1052 while (i > nulloffset) component[i--] = US"";
1053 }
1054
1055 /* Now turn the components into binary in pairs and bung them
1056 into the vector of ints. */
1057
1058 for (i = 0; i < v6count; i += 2)
1059 bin[i/2] = (Ustrtol(component[i], NULL, 16) << 16) +
1060 Ustrtol(component[i+1], NULL, 16);
1061
1062 /* If there was no terminating v4 component, we are done. */
1063
1064 if (!ipv4_ends) return 4;
1065 }
1066
1067 /* Handle IPv4 address */
1068
1069 (void)sscanf(CS address, "%d.%d.%d.%d", x, x+1, x+2, x+3);
1070 bin[v4offset] = (x[0] << 24) + (x[1] << 16) + (x[2] << 8) + x[3];
1071 return v4offset+1;
1072 }
1073
1074
1075 /*************************************************
1076 * Apply mask to an IP address *
1077 *************************************************/
1078
1079 /* Mask an address held in 1 or 4 ints, with the ms bit in the ms bit of the
1080 first int, etc.
1081
1082 Arguments:
1083 count the number of ints
1084 binary points to the ints to be masked
1085 mask the count of ms bits to leave, or -1 if no masking
1086
1087 Returns: nothing
1088 */
1089
1090 void
1091 host_mask(int count, int *binary, int mask)
1092 {
1093 int i;
1094 if (mask < 0) mask = 99999;
1095 for (i = 0; i < count; i++)
1096 {
1097 int wordmask;
1098 if (mask == 0) wordmask = 0;
1099 else if (mask < 32)
1100 {
1101 wordmask = (-1) << (32 - mask);
1102 mask = 0;
1103 }
1104 else
1105 {
1106 wordmask = -1;
1107 mask -= 32;
1108 }
1109 binary[i] &= wordmask;
1110 }
1111 }
1112
1113
1114
1115
1116 /*************************************************
1117 * Convert masked IP address in ints to text *
1118 *************************************************/
1119
1120 /* We can't use host_ntoa() because it assumes the binary values are in network
1121 byte order, and these are the result of host_aton(), which puts them in ints in
1122 host byte order. Also, we really want IPv6 addresses to be in a canonical
1123 format, so we output them with no abbreviation. In a number of cases we can't
1124 use the normal colon separator in them because it terminates keys in lsearch
1125 files, so we want to use dot instead. There's an argument that specifies what
1126 to use for IPv6 addresses.
1127
1128 Arguments:
1129 count 1 or 4 (number of ints)
1130 binary points to the ints
1131 mask mask value; if < 0 don't add to result
1132 buffer big enough to hold the result
1133 sep component separator character for IPv6 addresses
1134
1135 Returns: the number of characters placed in buffer, not counting
1136 the final nul.
1137 */
1138
1139 int
1140 host_nmtoa(int count, int *binary, int mask, uschar *buffer, int sep)
1141 {
1142 int i, j;
1143 uschar *tt = buffer;
1144
1145 if (count == 1)
1146 {
1147 j = binary[0];
1148 for (i = 24; i >= 0; i -= 8)
1149 {
1150 sprintf(CS tt, "%d.", (j >> i) & 255);
1151 while (*tt) tt++;
1152 }
1153 }
1154 else
1155 {
1156 for (i = 0; i < 4; i++)
1157 {
1158 j = binary[i];
1159 sprintf(CS tt, "%04x%c%04x%c", (j >> 16) & 0xffff, sep, j & 0xffff, sep);
1160 while (*tt) tt++;
1161 }
1162 }
1163
1164 tt--; /* lose final separator */
1165
1166 if (mask < 0)
1167 *tt = 0;
1168 else
1169 {
1170 sprintf(CS tt, "/%d", mask);
1171 while (*tt) tt++;
1172 }
1173
1174 return tt - buffer;
1175 }
1176
1177
1178
1179 /*************************************************
1180 * Check port for tls_on_connect *
1181 *************************************************/
1182
1183 /* This function checks whether a given incoming port is configured for tls-
1184 on-connect. It is called from the daemon and from inetd handling. If the global
1185 option tls_on_connect is already set, all ports operate this way. Otherwise, we
1186 check the tls_on_connect_ports option for a list of ports.
1187
1188 Argument: a port number
1189 Returns: TRUE or FALSE
1190 */
1191
1192 BOOL
1193 host_is_tls_on_connect_port(int port)
1194 {
1195 int sep = 0;
1196 uschar buffer[32];
1197 const uschar *list = tls_in.on_connect_ports;
1198 uschar *s;
1199 uschar *end;
1200
1201 if (tls_in.on_connect) return TRUE;
1202
1203 while ((s = string_nextinlist(&list, &sep, buffer, sizeof(buffer))))
1204 if (Ustrtol(s, &end, 10) == port)
1205 return TRUE;
1206
1207 return FALSE;
1208 }
1209
1210
1211
1212 /*************************************************
1213 * Check whether host is in a network *
1214 *************************************************/
1215
1216 /* This function checks whether a given IP address matches a pattern that
1217 represents either a single host, or a network (using CIDR notation). The caller
1218 of this function must check the syntax of the arguments before calling it.
1219
1220 Arguments:
1221 host string representation of the ip-address to check
1222 net string representation of the network, with optional CIDR mask
1223 maskoffset offset to the / that introduces the mask in the key
1224 zero if there is no mask
1225
1226 Returns:
1227 TRUE the host is inside the network
1228 FALSE the host is NOT inside the network
1229 */
1230
1231 BOOL
1232 host_is_in_net(const uschar *host, const uschar *net, int maskoffset)
1233 {
1234 int i;
1235 int address[4];
1236 int incoming[4];
1237 int mlen;
1238 int size = host_aton(net, address);
1239 int insize;
1240
1241 /* No mask => all bits to be checked */
1242
1243 if (maskoffset == 0) mlen = 99999; /* Big number */
1244 else mlen = Uatoi(net + maskoffset + 1);
1245
1246 /* Convert the incoming address to binary. */
1247
1248 insize = host_aton(host, incoming);
1249
1250 /* Convert IPv4 addresses given in IPv6 compatible mode, which represent
1251 connections from IPv4 hosts to IPv6 hosts, that is, addresses of the form
1252 ::ffff:<v4address>, to IPv4 format. */
1253
1254 if (insize == 4 && incoming[0] == 0 && incoming[1] == 0 &&
1255 incoming[2] == 0xffff)
1256 {
1257 insize = 1;
1258 incoming[0] = incoming[3];
1259 }
1260
1261 /* No match if the sizes don't agree. */
1262
1263 if (insize != size) return FALSE;
1264
1265 /* Else do the masked comparison. */
1266
1267 for (i = 0; i < size; i++)
1268 {
1269 int mask;
1270 if (mlen == 0) mask = 0;
1271 else if (mlen < 32)
1272 {
1273 mask = (-1) << (32 - mlen);
1274 mlen = 0;
1275 }
1276 else
1277 {
1278 mask = -1;
1279 mlen -= 32;
1280 }
1281 if ((incoming[i] & mask) != (address[i] & mask)) return FALSE;
1282 }
1283
1284 return TRUE;
1285 }
1286
1287
1288
1289 /*************************************************
1290 * Scan host list for local hosts *
1291 *************************************************/
1292
1293 /* Scan through a chain of addresses and check whether any of them is the
1294 address of an interface on the local machine. If so, remove that address and
1295 any previous ones with the same MX value, and all subsequent ones (which will
1296 have greater or equal MX values) from the chain. Note: marking them as unusable
1297 is NOT the right thing to do because it causes the hosts not to be used for
1298 other domains, for which they may well be correct.
1299
1300 The hosts may be part of a longer chain; we only process those between the
1301 initial pointer and the "last" pointer.
1302
1303 There is also a list of "pseudo-local" host names which are checked against the
1304 host names. Any match causes that host item to be treated the same as one which
1305 matches a local IP address.
1306
1307 If the very first host is a local host, then all MX records had a precedence
1308 greater than or equal to that of the local host. Either there's a problem in
1309 the DNS, or an apparently remote name turned out to be an abbreviation for the
1310 local host. Give a specific return code, and let the caller decide what to do.
1311 Otherwise, give a success code if at least one host address has been found.
1312
1313 Arguments:
1314 host pointer to the first host in the chain
1315 lastptr pointer to pointer to the last host in the chain (may be updated)
1316 removed if not NULL, set TRUE if some local addresses were removed
1317 from the list
1318
1319 Returns:
1320 HOST_FOUND if there is at least one host with an IP address on the chain
1321 and an MX value less than any MX value associated with the
1322 local host
1323 HOST_FOUND_LOCAL if a local host is among the lowest-numbered MX hosts; when
1324 the host addresses were obtained from A records or
1325 gethostbyname(), the MX values are set to -1.
1326 HOST_FIND_FAILED if no valid hosts with set IP addresses were found
1327 */
1328
1329 int
1330 host_scan_for_local_hosts(host_item *host, host_item **lastptr, BOOL *removed)
1331 {
1332 int yield = HOST_FIND_FAILED;
1333 host_item *last = *lastptr;
1334 host_item *prev = NULL;
1335 host_item *h;
1336
1337 if (removed != NULL) *removed = FALSE;
1338
1339 if (local_interface_data == NULL) local_interface_data = host_find_interfaces();
1340
1341 for (h = host; h != last->next; h = h->next)
1342 {
1343 #ifndef STAND_ALONE
1344 if (hosts_treat_as_local != NULL)
1345 {
1346 int rc;
1347 const uschar *save = deliver_domain;
1348 deliver_domain = h->name; /* set $domain */
1349 rc = match_isinlist(string_copylc(h->name), CUSS &hosts_treat_as_local, 0,
1350 &domainlist_anchor, NULL, MCL_DOMAIN, TRUE, NULL);
1351 deliver_domain = save;
1352 if (rc == OK) goto FOUND_LOCAL;
1353 }
1354 #endif
1355
1356 /* It seems that on many operating systems, 0.0.0.0 is treated as a synonym
1357 for 127.0.0.1 and refers to the local host. We therefore force it always to
1358 be treated as local. */
1359
1360 if (h->address != NULL)
1361 {
1362 ip_address_item *ip;
1363 if (Ustrcmp(h->address, "0.0.0.0") == 0) goto FOUND_LOCAL;
1364 for (ip = local_interface_data; ip != NULL; ip = ip->next)
1365 if (Ustrcmp(h->address, ip->address) == 0) goto FOUND_LOCAL;
1366 yield = HOST_FOUND; /* At least one remote address has been found */
1367 }
1368
1369 /* Update prev to point to the last host item before any that have
1370 the same MX value as the one we have just considered. */
1371
1372 if (h->next == NULL || h->next->mx != h->mx) prev = h;
1373 }
1374
1375 return yield; /* No local hosts found: return HOST_FOUND or HOST_FIND_FAILED */
1376
1377 /* A host whose IP address matches a local IP address, or whose name matches
1378 something in hosts_treat_as_local has been found. */
1379
1380 FOUND_LOCAL:
1381
1382 if (prev == NULL)
1383 {
1384 HDEBUG(D_host_lookup) debug_printf((h->mx >= 0)?
1385 "local host has lowest MX\n" :
1386 "local host found for non-MX address\n");
1387 return HOST_FOUND_LOCAL;
1388 }
1389
1390 HDEBUG(D_host_lookup)
1391 {
1392 debug_printf("local host in host list - removed hosts:\n");
1393 for (h = prev->next; h != last->next; h = h->next)
1394 debug_printf(" %s %s %d\n", h->name, h->address, h->mx);
1395 }
1396
1397 if (removed != NULL) *removed = TRUE;
1398 prev->next = last->next;
1399 *lastptr = prev;
1400 return yield;
1401 }
1402
1403
1404
1405
1406 /*************************************************
1407 * Remove duplicate IPs in host list *
1408 *************************************************/
1409
1410 /* You would think that administrators could set up their DNS records so that
1411 one ended up with a list of unique IP addresses after looking up A or MX
1412 records, but apparently duplication is common. So we scan such lists and
1413 remove the later duplicates. Note that we may get lists in which some host
1414 addresses are not set.
1415
1416 Arguments:
1417 host pointer to the first host in the chain
1418 lastptr pointer to pointer to the last host in the chain (may be updated)
1419
1420 Returns: nothing
1421 */
1422
1423 static void
1424 host_remove_duplicates(host_item *host, host_item **lastptr)
1425 {
1426 while (host != *lastptr)
1427 {
1428 if (host->address != NULL)
1429 {
1430 host_item *h = host;
1431 while (h != *lastptr)
1432 {
1433 if (h->next->address != NULL &&
1434 Ustrcmp(h->next->address, host->address) == 0)
1435 {
1436 DEBUG(D_host_lookup) debug_printf("duplicate IP address %s (MX=%d) "
1437 "removed\n", host->address, h->next->mx);
1438 if (h->next == *lastptr) *lastptr = h;
1439 h->next = h->next->next;
1440 }
1441 else h = h->next;
1442 }
1443 }
1444 /* If the last item was removed, host may have become == *lastptr */
1445 if (host != *lastptr) host = host->next;
1446 }
1447 }
1448
1449
1450
1451
1452 /*************************************************
1453 * Find sender host name by gethostbyaddr() *
1454 *************************************************/
1455
1456 /* This used to be the only way it was done, but it turns out that not all
1457 systems give aliases for calls to gethostbyaddr() - or one of the modern
1458 equivalents like getipnodebyaddr(). Fortunately, multiple PTR records are rare,
1459 but they can still exist. This function is now used only when a DNS lookup of
1460 the IP address fails, in order to give access to /etc/hosts.
1461
1462 Arguments: none
1463 Returns: OK, DEFER, FAIL
1464 */
1465
1466 static int
1467 host_name_lookup_byaddr(void)
1468 {
1469 int len;
1470 uschar *s, *t;
1471 struct hostent *hosts;
1472 struct in_addr addr;
1473 unsigned long time_msec;
1474
1475 if (slow_lookup_log) time_msec = get_time_in_ms();
1476
1477 /* Lookup on IPv6 system */
1478
1479 #if HAVE_IPV6
1480 if (Ustrchr(sender_host_address, ':') != NULL)
1481 {
1482 struct in6_addr addr6;
1483 if (inet_pton(AF_INET6, CS sender_host_address, &addr6) != 1)
1484 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "unable to parse \"%s\" as an "
1485 "IPv6 address", sender_host_address);
1486 #if HAVE_GETIPNODEBYADDR
1487 hosts = getipnodebyaddr(CS &addr6, sizeof(addr6), AF_INET6, &h_errno);
1488 #else
1489 hosts = gethostbyaddr(CS &addr6, sizeof(addr6), AF_INET6);
1490 #endif
1491 }
1492 else
1493 {
1494 if (inet_pton(AF_INET, CS sender_host_address, &addr) != 1)
1495 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "unable to parse \"%s\" as an "
1496 "IPv4 address", sender_host_address);
1497 #if HAVE_GETIPNODEBYADDR
1498 hosts = getipnodebyaddr(CS &addr, sizeof(addr), AF_INET, &h_errno);
1499 #else
1500 hosts = gethostbyaddr(CS &addr, sizeof(addr), AF_INET);
1501 #endif
1502 }
1503
1504 /* Do lookup on IPv4 system */
1505
1506 #else
1507 addr.s_addr = (S_ADDR_TYPE)inet_addr(CS sender_host_address);
1508 hosts = gethostbyaddr(CS(&addr), sizeof(addr), AF_INET);
1509 #endif
1510
1511 if ( slow_lookup_log
1512 && (time_msec = get_time_in_ms() - time_msec) > slow_lookup_log
1513 )
1514 log_long_lookup(US"name", sender_host_address, time_msec);
1515
1516 /* Failed to look up the host. */
1517
1518 if (hosts == NULL)
1519 {
1520 HDEBUG(D_host_lookup) debug_printf("IP address lookup failed: h_errno=%d\n",
1521 h_errno);
1522 return (h_errno == TRY_AGAIN || h_errno == NO_RECOVERY) ? DEFER : FAIL;
1523 }
1524
1525 /* It seems there are some records in the DNS that yield an empty name. We
1526 treat this as non-existent. In some operating systems, this is returned as an
1527 empty string; in others as a single dot. */
1528
1529 if (hosts->h_name == NULL || hosts->h_name[0] == 0 || hosts->h_name[0] == '.')
1530 {
1531 HDEBUG(D_host_lookup) debug_printf("IP address lookup yielded an empty name: "
1532 "treated as non-existent host name\n");
1533 return FAIL;
1534 }
1535
1536 /* Copy and lowercase the name, which is in static storage in many systems.
1537 Put it in permanent memory. */
1538
1539 s = (uschar *)hosts->h_name;
1540 len = Ustrlen(s) + 1;
1541 t = sender_host_name = store_get_perm(len);
1542 while (*s != 0) *t++ = tolower(*s++);
1543 *t = 0;
1544
1545 /* If the host has aliases, build a copy of the alias list */
1546
1547 if (hosts->h_aliases != NULL)
1548 {
1549 int count = 1;
1550 uschar **aliases, **ptr;
1551 for (aliases = USS hosts->h_aliases; *aliases != NULL; aliases++) count++;
1552 ptr = sender_host_aliases = store_get_perm(count * sizeof(uschar *));
1553 for (aliases = USS hosts->h_aliases; *aliases != NULL; aliases++)
1554 {
1555 uschar *s = *aliases;
1556 int len = Ustrlen(s) + 1;
1557 uschar *t = *ptr++ = store_get_perm(len);
1558 while (*s != 0) *t++ = tolower(*s++);
1559 *t = 0;
1560 }
1561 *ptr = NULL;
1562 }
1563
1564 return OK;
1565 }
1566
1567
1568
1569 /*************************************************
1570 * Find host name for incoming call *
1571 *************************************************/
1572
1573 /* Put the name in permanent store, pointed to by sender_host_name. We also set
1574 up a list of alias names, pointed to by sender_host_alias. The list is
1575 NULL-terminated. The incoming address is in sender_host_address, either in
1576 dotted-quad form for IPv4 or in colon-separated form for IPv6.
1577
1578 This function does a thorough check that the names it finds point back to the
1579 incoming IP address. Any that do not are discarded. Note that this is relied on
1580 by the ACL reverse_host_lookup check.
1581
1582 On some systems, get{host,ipnode}byaddr() appears to do this internally, but
1583 this it not universally true. Also, for release 4.30, this function was changed
1584 to do a direct DNS lookup first, by default[1], because it turns out that that
1585 is the only guaranteed way to find all the aliases on some systems. My
1586 experiments indicate that Solaris gethostbyaddr() gives the aliases for but
1587 Linux does not.
1588
1589 [1] The actual order is controlled by the host_lookup_order option.
1590
1591 Arguments: none
1592 Returns: OK on success, the answer being placed in the global variable
1593 sender_host_name, with any aliases in a list hung off
1594 sender_host_aliases
1595 FAIL if no host name can be found
1596 DEFER if a temporary error was encountered
1597
1598 The variable host_lookup_msg is set to an empty string on sucess, or to a
1599 reason for the failure otherwise, in a form suitable for tagging onto an error
1600 message, and also host_lookup_failed is set TRUE if the lookup failed. If there
1601 was a defer, host_lookup_deferred is set TRUE.
1602
1603 Any dynamically constructed string for host_lookup_msg must be in permanent
1604 store, because it might be used for several incoming messages on the same SMTP
1605 connection. */
1606
1607 int
1608 host_name_lookup(void)
1609 {
1610 int old_pool, rc;
1611 int sep = 0;
1612 uschar *hname, *save_hostname;
1613 uschar **aliases;
1614 uschar buffer[256];
1615 uschar *ordername;
1616 const uschar *list = host_lookup_order;
1617 dns_record *rr;
1618 dns_answer dnsa;
1619 dns_scan dnss;
1620
1621 sender_host_dnssec = host_lookup_deferred = host_lookup_failed = FALSE;
1622
1623 HDEBUG(D_host_lookup)
1624 debug_printf("looking up host name for %s\n", sender_host_address);
1625
1626 /* For testing the case when a lookup does not complete, we have a special
1627 reserved IP address. */
1628
1629 if (running_in_test_harness &&
1630 Ustrcmp(sender_host_address, "99.99.99.99") == 0)
1631 {
1632 HDEBUG(D_host_lookup)
1633 debug_printf("Test harness: host name lookup returns DEFER\n");
1634 host_lookup_deferred = TRUE;
1635 return DEFER;
1636 }
1637
1638 /* Do lookups directly in the DNS or via gethostbyaddr() (or equivalent), in
1639 the order specified by the host_lookup_order option. */
1640
1641 while ((ordername = string_nextinlist(&list, &sep, buffer, sizeof(buffer))))
1642 {
1643 if (strcmpic(ordername, US"bydns") == 0)
1644 {
1645 dns_init(FALSE, FALSE, FALSE); /* dnssec ctrl by dns_dnssec_ok glbl */
1646 dns_build_reverse(sender_host_address, buffer);
1647 rc = dns_lookup_timerwrap(&dnsa, buffer, T_PTR, NULL);
1648
1649 /* The first record we come across is used for the name; others are
1650 considered to be aliases. We have to scan twice, in order to find out the
1651 number of aliases. However, if all the names are empty, we will behave as
1652 if failure. (PTR records that yield empty names have been encountered in
1653 the DNS.) */
1654
1655 if (rc == DNS_SUCCEED)
1656 {
1657 uschar **aptr = NULL;
1658 int ssize = 264;
1659 int count = 0;
1660 int old_pool = store_pool;
1661
1662 sender_host_dnssec = dns_is_secure(&dnsa);
1663 DEBUG(D_dns)
1664 debug_printf("Reverse DNS security status: %s\n",
1665 sender_host_dnssec ? "DNSSEC verified (AD)" : "unverified");
1666
1667 store_pool = POOL_PERM; /* Save names in permanent storage */
1668
1669 for (rr = dns_next_rr(&dnsa, &dnss, RESET_ANSWERS);
1670 rr;
1671 rr = dns_next_rr(&dnsa, &dnss, RESET_NEXT))
1672 if (rr->type == T_PTR)
1673 count++;
1674
1675 /* Get store for the list of aliases. For compatibility with
1676 gethostbyaddr, we make an empty list if there are none. */
1677
1678 aptr = sender_host_aliases = store_get(count * sizeof(uschar *));
1679
1680 /* Re-scan and extract the names */
1681
1682 for (rr = dns_next_rr(&dnsa, &dnss, RESET_ANSWERS);
1683 rr;
1684 rr = dns_next_rr(&dnsa, &dnss, RESET_NEXT))
1685 {
1686 uschar *s = NULL;
1687 if (rr->type != T_PTR) continue;
1688 s = store_get(ssize);
1689
1690 /* If an overlong response was received, the data will have been
1691 truncated and dn_expand may fail. */
1692
1693 if (dn_expand(dnsa.answer, dnsa.answer + dnsa.answerlen,
1694 (uschar *)(rr->data), (DN_EXPAND_ARG4_TYPE)(s), ssize) < 0)
1695 {
1696 log_write(0, LOG_MAIN, "host name alias list truncated for %s",
1697 sender_host_address);
1698 break;
1699 }
1700
1701 store_reset(s + Ustrlen(s) + 1);
1702 if (s[0] == 0)
1703 {
1704 HDEBUG(D_host_lookup) debug_printf("IP address lookup yielded an "
1705 "empty name: treated as non-existent host name\n");
1706 continue;
1707 }
1708 if (!sender_host_name) sender_host_name = s;
1709 else *aptr++ = s;
1710 while (*s != 0) { *s = tolower(*s); s++; }
1711 }
1712
1713 *aptr = NULL; /* End of alias list */
1714 store_pool = old_pool; /* Reset store pool */
1715
1716 /* If we've found a names, break out of the "order" loop */
1717
1718 if (sender_host_name != NULL) break;
1719 }
1720
1721 /* If the DNS lookup deferred, we must also defer. */
1722
1723 if (rc == DNS_AGAIN)
1724 {
1725 HDEBUG(D_host_lookup)
1726 debug_printf("IP address PTR lookup gave temporary error\n");
1727 host_lookup_deferred = TRUE;
1728 return DEFER;
1729 }
1730 }
1731
1732 /* Do a lookup using gethostbyaddr() - or equivalent */
1733
1734 else if (strcmpic(ordername, US"byaddr") == 0)
1735 {
1736 HDEBUG(D_host_lookup)
1737 debug_printf("IP address lookup using gethostbyaddr()\n");
1738 rc = host_name_lookup_byaddr();
1739 if (rc == DEFER)
1740 {
1741 host_lookup_deferred = TRUE;
1742 return rc; /* Can't carry on */
1743 }
1744 if (rc == OK) break; /* Found a name */
1745 }
1746 } /* Loop for bydns/byaddr scanning */
1747
1748 /* If we have failed to find a name, return FAIL and log when required.
1749 NB host_lookup_msg must be in permanent store. */
1750
1751 if (sender_host_name == NULL)
1752 {
1753 if (host_checking || !log_testing_mode)
1754 log_write(L_host_lookup_failed, LOG_MAIN, "no host name found for IP "
1755 "address %s", sender_host_address);
1756 host_lookup_msg = US" (failed to find host name from IP address)";
1757 host_lookup_failed = TRUE;
1758 return FAIL;
1759 }
1760
1761 HDEBUG(D_host_lookup)
1762 {
1763 uschar **aliases = sender_host_aliases;
1764 debug_printf("IP address lookup yielded \"%s\"\n", sender_host_name);
1765 while (*aliases != NULL) debug_printf(" alias \"%s\"\n", *aliases++);
1766 }
1767
1768 /* We need to verify that a forward lookup on the name we found does indeed
1769 correspond to the address. This is for security: in principle a malefactor who
1770 happened to own a reverse zone could set it to point to any names at all.
1771
1772 This code was present in versions of Exim before 3.20. At that point I took it
1773 out because I thought that gethostbyaddr() did the check anyway. It turns out
1774 that this isn't always the case, so it's coming back in at 4.01. This version
1775 is actually better, because it also checks aliases.
1776
1777 The code was made more robust at release 4.21. Prior to that, it accepted all
1778 the names if any of them had the correct IP address. Now the code checks all
1779 the names, and accepts only those that have the correct IP address. */
1780
1781 save_hostname = sender_host_name; /* Save for error messages */
1782 aliases = sender_host_aliases;
1783 for (hname = sender_host_name; hname != NULL; hname = *aliases++)
1784 {
1785 int rc;
1786 BOOL ok = FALSE;
1787 host_item h;
1788 dnssec_domains d;
1789
1790 h.next = NULL;
1791 h.name = hname;
1792 h.mx = MX_NONE;
1793 h.address = NULL;
1794 d.request = sender_host_dnssec ? US"*" : NULL;;
1795 d.require = NULL;
1796
1797 if ( (rc = host_find_bydns(&h, NULL, HOST_FIND_BY_A,
1798 NULL, NULL, NULL, &d, NULL, NULL)) == HOST_FOUND
1799 || rc == HOST_FOUND_LOCAL
1800 )
1801 {
1802 host_item *hh;
1803 HDEBUG(D_host_lookup) debug_printf("checking addresses for %s\n", hname);
1804
1805 /* If the forward lookup was not secure we cancel the is-secure variable */
1806
1807 DEBUG(D_dns) debug_printf("Forward DNS security status: %s\n",
1808 h.dnssec == DS_YES ? "DNSSEC verified (AD)" : "unverified");
1809 if (h.dnssec != DS_YES) sender_host_dnssec = FALSE;
1810
1811 for (hh = &h; hh != NULL; hh = hh->next)
1812 if (host_is_in_net(hh->address, sender_host_address, 0))
1813 {
1814 HDEBUG(D_host_lookup) debug_printf(" %s OK\n", hh->address);
1815 ok = TRUE;
1816 break;
1817 }
1818 else
1819 HDEBUG(D_host_lookup) debug_printf(" %s\n", hh->address);
1820
1821 if (!ok) HDEBUG(D_host_lookup)
1822 debug_printf("no IP address for %s matched %s\n", hname,
1823 sender_host_address);
1824 }
1825 else if (rc == HOST_FIND_AGAIN)
1826 {
1827 HDEBUG(D_host_lookup) debug_printf("temporary error for host name lookup\n");
1828 host_lookup_deferred = TRUE;
1829 sender_host_name = NULL;
1830 return DEFER;
1831 }
1832 else
1833 HDEBUG(D_host_lookup) debug_printf("no IP addresses found for %s\n", hname);
1834
1835 /* If this name is no good, and it's the sender name, set it null pro tem;
1836 if it's an alias, just remove it from the list. */
1837
1838 if (!ok)
1839 {
1840 if (hname == sender_host_name) sender_host_name = NULL; else
1841 {
1842 uschar **a; /* Don't amalgamate - some */
1843 a = --aliases; /* compilers grumble */
1844 while (*a != NULL) { *a = a[1]; a++; }
1845 }
1846 }
1847 }
1848
1849 /* If sender_host_name == NULL, it means we didn't like the name. Replace
1850 it with the first alias, if there is one. */
1851
1852 if (sender_host_name == NULL && *sender_host_aliases != NULL)
1853 sender_host_name = *sender_host_aliases++;
1854
1855 /* If we now have a main name, all is well. */
1856
1857 if (sender_host_name != NULL) return OK;
1858
1859 /* We have failed to find an address that matches. */
1860
1861 HDEBUG(D_host_lookup)
1862 debug_printf("%s does not match any IP address for %s\n",
1863 sender_host_address, save_hostname);
1864
1865 /* This message must be in permanent store */
1866
1867 old_pool = store_pool;
1868 store_pool = POOL_PERM;
1869 host_lookup_msg = string_sprintf(" (%s does not match any IP address for %s)",
1870 sender_host_address, save_hostname);
1871 store_pool = old_pool;
1872 host_lookup_failed = TRUE;
1873 return FAIL;
1874 }
1875
1876
1877
1878
1879 /*************************************************
1880 * Find IP address(es) for host by name *
1881 *************************************************/
1882
1883 /* The input is a host_item structure with the name filled in and the address
1884 field set to NULL. We use gethostbyname() or getipnodebyname() or
1885 gethostbyname2(), as appropriate. Of course, these functions may use the DNS,
1886 but they do not do MX processing. It appears, however, that in some systems the
1887 current setting of resolver options is used when one of these functions calls
1888 the resolver. For this reason, we call dns_init() at the start, with arguments
1889 influenced by bits in "flags", just as we do for host_find_bydns().
1890
1891 The second argument provides a host list (usually an IP list) of hosts to
1892 ignore. This makes it possible to ignore IPv6 link-local addresses or loopback
1893 addresses in unreasonable places.
1894
1895 The lookup may result in a change of name. For compatibility with the dns
1896 lookup, return this via fully_qualified_name as well as updating the host item.
1897 The lookup may also yield more than one IP address, in which case chain on
1898 subsequent host_item structures.
1899
1900 Arguments:
1901 host a host item with the name and MX filled in;
1902 the address is to be filled in;
1903 multiple IP addresses cause other host items to be
1904 chained on.
1905 ignore_target_hosts a list of hosts to ignore
1906 flags HOST_FIND_QUALIFY_SINGLE ) passed to
1907 HOST_FIND_SEARCH_PARENTS ) dns_init()
1908 fully_qualified_name if not NULL, set to point to host name for
1909 compatibility with host_find_bydns
1910 local_host_check TRUE if a check for the local host is wanted
1911
1912 Returns: HOST_FIND_FAILED Failed to find the host or domain
1913 HOST_FIND_AGAIN Try again later
1914 HOST_FOUND Host found - data filled in
1915 HOST_FOUND_LOCAL Host found and is the local host
1916 */
1917
1918 int
1919 host_find_byname(host_item *host, const uschar *ignore_target_hosts, int flags,
1920 const uschar **fully_qualified_name, BOOL local_host_check)
1921 {
1922 int i, yield, times;
1923 uschar **addrlist;
1924 host_item *last = NULL;
1925 BOOL temp_error = FALSE;
1926 #if HAVE_IPV6
1927 int af;
1928 #endif
1929
1930 /* Make sure DNS options are set as required. This appears to be necessary in
1931 some circumstances when the get..byname() function actually calls the DNS. */
1932
1933 dns_init((flags & HOST_FIND_QUALIFY_SINGLE) != 0,
1934 (flags & HOST_FIND_SEARCH_PARENTS) != 0,
1935 FALSE); /* Cannot retrieve dnssec status so do not request */
1936
1937 /* In an IPv6 world, unless IPv6 has been disabled, we need to scan for both
1938 kinds of address, so go round the loop twice. Note that we have ensured that
1939 AF_INET6 is defined even in an IPv4 world, which makes for slightly tidier
1940 code. However, if dns_ipv4_lookup matches the domain, we also just do IPv4
1941 lookups here (except when testing standalone). */
1942
1943 #if HAVE_IPV6
1944 #ifdef STAND_ALONE
1945 if (disable_ipv6)
1946 #else
1947 if (disable_ipv6 ||
1948 (dns_ipv4_lookup != NULL &&
1949 match_isinlist(host->name, CUSS &dns_ipv4_lookup, 0, NULL, NULL,
1950 MCL_DOMAIN, TRUE, NULL) == OK))
1951 #endif
1952
1953 { af = AF_INET; times = 1; }
1954 else
1955 { af = AF_INET6; times = 2; }
1956
1957 /* No IPv6 support */
1958
1959 #else /* HAVE_IPV6 */
1960 times = 1;
1961 #endif /* HAVE_IPV6 */
1962
1963 /* Initialize the flag that gets set for DNS syntax check errors, so that the
1964 interface to this function can be similar to host_find_bydns. */
1965
1966 host_find_failed_syntax = FALSE;
1967
1968 /* Loop to look up both kinds of address in an IPv6 world */
1969
1970 for (i = 1; i <= times;
1971 #if HAVE_IPV6
1972 af = AF_INET, /* If 2 passes, IPv4 on the second */
1973 #endif
1974 i++)
1975 {
1976 BOOL ipv4_addr;
1977 int error_num = 0;
1978 struct hostent *hostdata;
1979 unsigned long time_msec = 0; /* compiler quietening */
1980
1981 #ifdef STAND_ALONE
1982 printf("Looking up: %s\n", host->name);
1983 #endif
1984
1985 if (slow_lookup_log) time_msec = get_time_in_ms();
1986
1987 #if HAVE_IPV6
1988 if (running_in_test_harness)
1989 hostdata = host_fake_gethostbyname(host->name, af, &error_num);
1990 else
1991 {
1992 #if HAVE_GETIPNODEBYNAME
1993 hostdata = getipnodebyname(CS host->name, af, 0, &error_num);
1994 #else
1995 hostdata = gethostbyname2(CS host->name, af);
1996 error_num = h_errno;
1997 #endif
1998 }
1999
2000 #else /* not HAVE_IPV6 */
2001 if (running_in_test_harness)
2002 hostdata = host_fake_gethostbyname(host->name, AF_INET, &error_num);
2003 else
2004 {
2005 hostdata = gethostbyname(CS host->name);
2006 error_num = h_errno;
2007 }
2008 #endif /* HAVE_IPV6 */
2009
2010 if ( slow_lookup_log
2011 && (time_msec = get_time_in_ms() - time_msec) > slow_lookup_log)
2012 log_long_lookup(US"name", host->name, time_msec);
2013
2014 if (hostdata == NULL)
2015 {
2016 uschar *error;
2017 switch (error_num)
2018 {
2019 case HOST_NOT_FOUND: error = US"HOST_NOT_FOUND"; break;
2020 case TRY_AGAIN: error = US"TRY_AGAIN"; break;
2021 case NO_RECOVERY: error = US"NO_RECOVERY"; break;
2022 case NO_DATA: error = US"NO_DATA"; break;
2023 #if NO_DATA != NO_ADDRESS
2024 case NO_ADDRESS: error = US"NO_ADDRESS"; break;
2025 #endif
2026 default: error = US"?"; break;
2027 }
2028
2029 DEBUG(D_host_lookup) debug_printf("%s returned %d (%s)\n",
2030 #if HAVE_IPV6
2031 #if HAVE_GETIPNODEBYNAME
2032 (af == AF_INET6)? "getipnodebyname(af=inet6)" : "getipnodebyname(af=inet)",
2033 #else
2034 (af == AF_INET6)? "gethostbyname2(af=inet6)" : "gethostbyname2(af=inet)",
2035 #endif
2036 #else
2037 "gethostbyname",
2038 #endif
2039 error_num, error);
2040
2041 if (error_num == TRY_AGAIN || error_num == NO_RECOVERY) temp_error = TRUE;
2042 continue;
2043 }
2044 if ((hostdata->h_addr_list)[0] == NULL) continue;
2045
2046 /* Replace the name with the fully qualified one if necessary, and fill in
2047 the fully_qualified_name pointer. */
2048
2049 if (hostdata->h_name[0] != 0 &&
2050 Ustrcmp(host->name, hostdata->h_name) != 0)
2051 host->name = string_copy_dnsdomain((uschar *)hostdata->h_name);
2052 if (fully_qualified_name != NULL) *fully_qualified_name = host->name;
2053
2054 /* Get the list of addresses. IPv4 and IPv6 addresses can be distinguished
2055 by their different lengths. Scan the list, ignoring any that are to be
2056 ignored, and build a chain from the rest. */
2057
2058 ipv4_addr = hostdata->h_length == sizeof(struct in_addr);
2059
2060 for (addrlist = USS hostdata->h_addr_list; *addrlist != NULL; addrlist++)
2061 {
2062 uschar *text_address =
2063 host_ntoa(ipv4_addr? AF_INET:AF_INET6, *addrlist, NULL, NULL);
2064
2065 #ifndef STAND_ALONE
2066 if (ignore_target_hosts != NULL &&
2067 verify_check_this_host(&ignore_target_hosts, NULL, host->name,
2068 text_address, NULL) == OK)
2069 {
2070 DEBUG(D_host_lookup)
2071 debug_printf("ignored host %s [%s]\n", host->name, text_address);
2072 continue;
2073 }
2074 #endif
2075
2076 /* If this is the first address, last == NULL and we put the data in the
2077 original block. */
2078
2079 if (last == NULL)
2080 {
2081 host->address = text_address;
2082 host->port = PORT_NONE;
2083 host->status = hstatus_unknown;
2084 host->why = hwhy_unknown;
2085 host->dnssec = DS_UNK;
2086 last = host;
2087 }
2088
2089 /* Else add further host item blocks for any other addresses, keeping
2090 the order. */
2091
2092 else
2093 {
2094 host_item *next = store_get(sizeof(host_item));
2095 next->name = host->name;
2096 next->mx = host->mx;
2097 next->address = text_address;
2098 next->port = PORT_NONE;
2099 next->status = hstatus_unknown;
2100 next->why = hwhy_unknown;
2101 next->dnssec = DS_UNK;
2102 next->last_try = 0;
2103 next->next = last->next;
2104 last->next = next;
2105 last = next;
2106 }
2107 }
2108 }
2109
2110 /* If no hosts were found, the address field in the original host block will be
2111 NULL. If temp_error is set, at least one of the lookups gave a temporary error,
2112 so we pass that back. */
2113
2114 if (host->address == NULL)
2115 {
2116 uschar *msg =
2117 #ifndef STAND_ALONE
2118 (message_id[0] == 0 && smtp_in != NULL)?
2119 string_sprintf("no IP address found for host %s (during %s)", host->name,
2120 smtp_get_connection_info()) :
2121 #endif
2122 string_sprintf("no IP address found for host %s", host->name);
2123
2124 HDEBUG(D_host_lookup) debug_printf("%s\n", msg);
2125 if (temp_error) goto RETURN_AGAIN;
2126 if (host_checking || !log_testing_mode)
2127 log_write(L_host_lookup_failed, LOG_MAIN, "%s", msg);
2128 return HOST_FIND_FAILED;
2129 }
2130
2131 /* Remove any duplicate IP addresses, then check to see if this is the local
2132 host if required. */
2133
2134 host_remove_duplicates(host, &last);
2135 yield = local_host_check?
2136 host_scan_for_local_hosts(host, &last, NULL) : HOST_FOUND;
2137
2138 HDEBUG(D_host_lookup)
2139 {
2140 const host_item *h;
2141 if (fully_qualified_name != NULL)
2142 debug_printf("fully qualified name = %s\n", *fully_qualified_name);
2143 debug_printf("%s looked up these IP addresses:\n",
2144 #if HAVE_IPV6
2145 #if HAVE_GETIPNODEBYNAME
2146 "getipnodebyname"
2147 #else
2148 "gethostbyname2"
2149 #endif
2150 #else
2151 "gethostbyname"
2152 #endif
2153 );
2154 for (h = host; h != last->next; h = h->next)
2155 debug_printf(" name=%s address=%s\n", h->name,
2156 (h->address == NULL)? US"<null>" : h->address);
2157 }
2158
2159 /* Return the found status. */
2160
2161 return yield;
2162
2163 /* Handle the case when there is a temporary error. If the name matches
2164 dns_again_means_nonexist, return permanent rather than temporary failure. */
2165
2166 RETURN_AGAIN:
2167 {
2168 #ifndef STAND_ALONE
2169 int rc;
2170 const uschar *save = deliver_domain;
2171 deliver_domain = host->name; /* set $domain */
2172 rc = match_isinlist(host->name, CUSS &dns_again_means_nonexist, 0, NULL, NULL,
2173 MCL_DOMAIN, TRUE, NULL);
2174 deliver_domain = save;
2175 if (rc == OK)
2176 {
2177 DEBUG(D_host_lookup) debug_printf("%s is in dns_again_means_nonexist: "
2178 "returning HOST_FIND_FAILED\n", host->name);
2179 return HOST_FIND_FAILED;
2180 }
2181 #endif
2182 return HOST_FIND_AGAIN;
2183 }
2184 }
2185
2186
2187
2188 /*************************************************
2189 * Fill in a host address from the DNS *
2190 *************************************************/
2191
2192 /* Given a host item, with its name, port and mx fields set, and its address
2193 field set to NULL, fill in its IP address from the DNS. If it is multi-homed,
2194 create additional host items for the additional addresses, copying all the
2195 other fields, and randomizing the order.
2196
2197 On IPv6 systems, A6 records are sought first (but only if support for A6 is
2198 configured - they may never become mainstream), then AAAA records are sought,
2199 and finally A records are sought as well.
2200
2201 The host name may be changed if the DNS returns a different name - e.g. fully
2202 qualified or changed via CNAME. If fully_qualified_name is not NULL, dns_lookup
2203 ensures that it points to the fully qualified name. However, this is the fully
2204 qualified version of the original name; if a CNAME is involved, the actual
2205 canonical host name may be different again, and so we get it directly from the
2206 relevant RR. Note that we do NOT change the mx field of the host item in this
2207 function as it may be called to set the addresses of hosts taken from MX
2208 records.
2209
2210 Arguments:
2211 host points to the host item we're filling in
2212 lastptr points to pointer to last host item in a chain of
2213 host items (may be updated if host is last and gets
2214 extended because multihomed)
2215 ignore_target_hosts list of hosts to ignore
2216 allow_ip if TRUE, recognize an IP address and return it
2217 fully_qualified_name if not NULL, return fully qualified name here if
2218 the contents are different (i.e. it must be preset
2219 to something)
2220 dnssec_request if TRUE request the AD bit
2221 dnssec_require if TRUE require the AD bit
2222
2223 Returns: HOST_FIND_FAILED couldn't find A record
2224 HOST_FIND_AGAIN try again later
2225 HOST_FOUND found AAAA and/or A record(s)
2226 HOST_IGNORED found, but all IPs ignored
2227 */
2228
2229 static int
2230 set_address_from_dns(host_item *host, host_item **lastptr,
2231 const uschar *ignore_target_hosts, BOOL allow_ip,
2232 const uschar **fully_qualified_name,
2233 BOOL dnssec_request, BOOL dnssec_require)
2234 {
2235 dns_record *rr;
2236 host_item *thishostlast = NULL; /* Indicates not yet filled in anything */
2237 BOOL v6_find_again = FALSE;
2238 int i;
2239
2240 /* If allow_ip is set, a name which is an IP address returns that value
2241 as its address. This is used for MX records when allow_mx_to_ip is set, for
2242 those sites that feel they have to flaunt the RFC rules. */
2243
2244 if (allow_ip && string_is_ip_address(host->name, NULL) != 0)
2245 {
2246 #ifndef STAND_ALONE
2247 if (ignore_target_hosts != NULL &&
2248 verify_check_this_host(&ignore_target_hosts, NULL, host->name,
2249 host->name, NULL) == OK)
2250 return HOST_IGNORED;
2251 #endif
2252
2253 host->address = host->name;
2254 return HOST_FOUND;
2255 }
2256
2257 /* On an IPv6 system, unless IPv6 is disabled, go round the loop up to twice,
2258 looking for AAAA records the first time. However, unless
2259 doing standalone testing, we force an IPv4 lookup if the domain matches
2260 dns_ipv4_lookup is set. On an IPv4 system, go round the
2261 loop once only, looking only for A records. */
2262
2263 #if HAVE_IPV6
2264 #ifndef STAND_ALONE
2265 if (disable_ipv6 || (dns_ipv4_lookup != NULL &&
2266 match_isinlist(host->name, CUSS &dns_ipv4_lookup, 0, NULL, NULL,
2267 MCL_DOMAIN, TRUE, NULL) == OK))
2268 i = 0; /* look up A records only */
2269 else
2270 #endif /* STAND_ALONE */
2271
2272 i = 1; /* look up AAAA and A records */
2273
2274 /* The IPv4 world */
2275
2276 #else /* HAVE_IPV6 */
2277 i = 0; /* look up A records only */
2278 #endif /* HAVE_IPV6 */
2279
2280 for (; i >= 0; i--)
2281 {
2282 static int types[] = { T_A, T_AAAA };
2283 int type = types[i];
2284 int randoffset = (i == 0)? 500 : 0; /* Ensures v6 sorts before v4 */
2285 dns_answer dnsa;
2286 dns_scan dnss;
2287
2288 int rc = dns_lookup_timerwrap(&dnsa, host->name, type, fully_qualified_name);
2289 lookup_dnssec_authenticated = !dnssec_request ? NULL
2290 : dns_is_secure(&dnsa) ? US"yes" : US"no";
2291
2292 DEBUG(D_dns)
2293 if ( (dnssec_request || dnssec_require)
2294 && !dns_is_secure(&dnsa)
2295 && dns_is_aa(&dnsa)
2296 )
2297 debug_printf("DNS lookup of %.256s (A/AAAA) requested AD, but got AA\n", host->name);
2298
2299 /* We want to return HOST_FIND_AGAIN if one of the A or AAAA lookups
2300 fails or times out, but not if another one succeeds. (In the early
2301 IPv6 days there are name servers that always fail on AAAA, but are happy
2302 to give out an A record. We want to proceed with that A record.) */
2303
2304 if (rc != DNS_SUCCEED)
2305 {
2306 if (i == 0) /* Just tried for an A record, i.e. end of loop */
2307 {
2308 if (host->address != NULL) return HOST_FOUND; /* AAAA was found */
2309 if (rc == DNS_AGAIN || rc == DNS_FAIL || v6_find_again)
2310 return HOST_FIND_AGAIN;
2311 return HOST_FIND_FAILED; /* DNS_NOMATCH or DNS_NODATA */
2312 }
2313
2314 /* Tried for an AAAA record: remember if this was a temporary
2315 error, and look for the next record type. */
2316
2317 if (rc != DNS_NOMATCH && rc != DNS_NODATA) v6_find_again = TRUE;
2318 continue;
2319 }
2320
2321 if (dnssec_request)
2322 {
2323 if (dns_is_secure(&dnsa))
2324 {
2325 DEBUG(D_host_lookup) debug_printf("%s A DNSSEC\n", host->name);
2326 if (host->dnssec == DS_UNK) /* set in host_find_bydns() */
2327 host->dnssec = DS_YES;
2328 }
2329 else
2330 {
2331 if (dnssec_require)
2332 {
2333 log_write(L_host_lookup_failed, LOG_MAIN,
2334 "dnssec fail on %s for %.256s",
2335 i>0 ? "AAAA" : "A", host->name);
2336 continue;
2337 }
2338 if (host->dnssec == DS_YES) /* set in host_find_bydns() */
2339 {
2340 DEBUG(D_host_lookup) debug_printf("%s A cancel DNSSEC\n", host->name);
2341 host->dnssec = DS_NO;
2342 lookup_dnssec_authenticated = US"no";
2343 }
2344 }
2345 }
2346
2347 /* Lookup succeeded: fill in the given host item with the first non-ignored
2348 address found; create additional items for any others. A single A6 record
2349 may generate more than one address. The lookup had a chance to update the
2350 fqdn; we do not want any later times round the loop to do so. */
2351
2352 fully_qualified_name = NULL;
2353
2354 for (rr = dns_next_rr(&dnsa, &dnss, RESET_ANSWERS);
2355 rr;
2356 rr = dns_next_rr(&dnsa, &dnss, RESET_NEXT))
2357 {
2358 if (rr->type == type)
2359 {
2360 /* dns_address *da = dns_address_from_rr(&dnsa, rr); */
2361
2362 dns_address *da;
2363 da = dns_address_from_rr(&dnsa, rr);
2364
2365 DEBUG(D_host_lookup)
2366 if (!da) debug_printf("no addresses extracted from A6 RR for %s\n",
2367 host->name);
2368
2369 /* This loop runs only once for A and AAAA records, but may run
2370 several times for an A6 record that generated multiple addresses. */
2371
2372 for (; da; da = da->next)
2373 {
2374 #ifndef STAND_ALONE
2375 if (ignore_target_hosts != NULL &&
2376 verify_check_this_host(&ignore_target_hosts, NULL,
2377 host->name, da->address, NULL) == OK)
2378 {
2379 DEBUG(D_host_lookup)
2380 debug_printf("ignored host %s [%s]\n", host->name, da->address);
2381 continue;
2382 }
2383 #endif
2384
2385 /* If this is the first address, stick it in the given host block,
2386 and change the name if the returned RR has a different name. */
2387
2388 if (thishostlast == NULL)
2389 {
2390 if (strcmpic(host->name, rr->name) != 0)
2391 host->name = string_copy_dnsdomain(rr->name);
2392 host->address = da->address;
2393 host->sort_key = host->mx * 1000 + random_number(500) + randoffset;
2394 host->status = hstatus_unknown;
2395 host->why = hwhy_unknown;
2396 thishostlast = host;
2397 }
2398
2399 /* Not the first address. Check for, and ignore, duplicates. Then
2400 insert in the chain at a random point. */
2401
2402 else
2403 {
2404 int new_sort_key;
2405 host_item *next;
2406
2407 /* End of our local chain is specified by "thishostlast". */
2408
2409 for (next = host;; next = next->next)
2410 {
2411 if (Ustrcmp(CS da->address, next->address) == 0) break;
2412 if (next == thishostlast) { next = NULL; break; }
2413 }
2414 if (next != NULL) continue; /* With loop for next address */
2415
2416 /* Not a duplicate */
2417
2418 new_sort_key = host->mx * 1000 + random_number(500) + randoffset;
2419 next = store_get(sizeof(host_item));
2420
2421 /* New address goes first: insert the new block after the first one
2422 (so as not to disturb the original pointer) but put the new address
2423 in the original block. */
2424
2425 if (new_sort_key < host->sort_key)
2426 {
2427 *next = *host; /* Copies port */
2428 host->next = next;
2429 host->address = da->address;
2430 host->sort_key = new_sort_key;
2431 if (thishostlast == host) thishostlast = next; /* Local last */
2432 if (*lastptr == host) *lastptr = next; /* Global last */
2433 }
2434
2435 /* Otherwise scan down the addresses for this host to find the
2436 one to insert after. */
2437
2438 else
2439 {
2440 host_item *h = host;
2441 while (h != thishostlast)
2442 {
2443 if (new_sort_key < h->next->sort_key) break;
2444 h = h->next;
2445 }
2446 *next = *h; /* Copies port */
2447 h->next = next;
2448 next->address = da->address;
2449 next->sort_key = new_sort_key;
2450 if (h == thishostlast) thishostlast = next; /* Local last */
2451 if (h == *lastptr) *lastptr = next; /* Global last */
2452 }
2453 }
2454 }
2455 }
2456 }
2457 }
2458
2459 /* Control gets here only if the econdookup (the A record) succeeded.
2460 However, the address may not be filled in if it was ignored. */
2461
2462 return host->address ? HOST_FOUND : HOST_IGNORED;
2463 }
2464
2465
2466
2467
2468 /*************************************************
2469 * Find IP addresses and host names via DNS *
2470 *************************************************/
2471
2472 /* The input is a host_item structure with the name field filled in and the
2473 address field set to NULL. This may be in a chain of other host items. The
2474 lookup may result in more than one IP address, in which case we must created
2475 new host blocks for the additional addresses, and insert them into the chain.
2476 The original name may not be fully qualified. Use the fully_qualified_name
2477 argument to return the official name, as returned by the resolver.
2478
2479 Arguments:
2480 host point to initial host item
2481 ignore_target_hosts a list of hosts to ignore
2482 whichrrs flags indicating which RRs to look for:
2483 HOST_FIND_BY_SRV => look for SRV
2484 HOST_FIND_BY_MX => look for MX
2485 HOST_FIND_BY_A => look for A or AAAA
2486 also flags indicating how the lookup is done
2487 HOST_FIND_QUALIFY_SINGLE ) passed to the
2488 HOST_FIND_SEARCH_PARENTS ) resolver
2489 srv_service when SRV used, the service name
2490 srv_fail_domains DNS errors for these domains => assume nonexist
2491 mx_fail_domains DNS errors for these domains => assume nonexist
2492 dnssec_d.request => make dnssec request: domainlist
2493 dnssec_d.require => ditto and nonexist failures
2494 fully_qualified_name if not NULL, return fully-qualified name
2495 removed set TRUE if local host was removed from the list
2496
2497 Returns: HOST_FIND_FAILED Failed to find the host or domain;
2498 if there was a syntax error,
2499 host_find_failed_syntax is set.
2500 HOST_FIND_AGAIN Could not resolve at this time
2501 HOST_FOUND Host found
2502 HOST_FOUND_LOCAL The lowest MX record points to this
2503 machine, if MX records were found, or
2504 an A record that was found contains
2505 an address of the local host
2506 */
2507
2508 int
2509 host_find_bydns(host_item *host, const uschar *ignore_target_hosts, int whichrrs,
2510 uschar *srv_service, uschar *srv_fail_domains, uschar *mx_fail_domains,
2511 const dnssec_domains *dnssec_d,
2512 const uschar **fully_qualified_name, BOOL *removed)
2513 {
2514 host_item *h, *last;
2515 dns_record *rr;
2516 int rc = DNS_FAIL;
2517 int ind_type = 0;
2518 int yield;
2519 dns_answer dnsa;
2520 dns_scan dnss;
2521 BOOL dnssec_require = dnssec_d
2522 && match_isinlist(host->name, CUSS &dnssec_d->require,
2523 0, NULL, NULL, MCL_DOMAIN, TRUE, NULL) == OK;
2524 BOOL dnssec_request = dnssec_require
2525 || ( dnssec_d
2526 && match_isinlist(host->name, CUSS &dnssec_d->request,
2527 0, NULL, NULL, MCL_DOMAIN, TRUE, NULL) == OK);
2528 dnssec_status_t dnssec;
2529
2530 /* Set the default fully qualified name to the incoming name, initialize the
2531 resolver if necessary, set up the relevant options, and initialize the flag
2532 that gets set for DNS syntax check errors. */
2533
2534 if (fully_qualified_name != NULL) *fully_qualified_name = host->name;
2535 dns_init((whichrrs & HOST_FIND_QUALIFY_SINGLE) != 0,
2536 (whichrrs & HOST_FIND_SEARCH_PARENTS) != 0,
2537 dnssec_request);
2538 host_find_failed_syntax = FALSE;
2539
2540 /* First, if requested, look for SRV records. The service name is given; we
2541 assume TCP protocol. DNS domain names are constrained to a maximum of 256
2542 characters, so the code below should be safe. */
2543
2544 if ((whichrrs & HOST_FIND_BY_SRV) != 0)
2545 {
2546 uschar buffer[300];
2547 uschar *temp_fully_qualified_name = buffer;
2548 int prefix_length;
2549
2550 (void)sprintf(CS buffer, "_%s._tcp.%n%.256s", srv_service, &prefix_length,
2551 host->name);
2552 ind_type = T_SRV;
2553
2554 /* Search for SRV records. If the fully qualified name is different to
2555 the input name, pass back the new original domain, without the prepended
2556 magic. */
2557
2558 dnssec = DS_UNK;
2559 lookup_dnssec_authenticated = NULL;
2560 rc = dns_lookup_timerwrap(&dnsa, buffer, ind_type, CUSS &temp_fully_qualified_name);
2561
2562 DEBUG(D_dns)
2563 if ((dnssec_request || dnssec_require)
2564 & !dns_is_secure(&dnsa)
2565 & dns_is_aa(&dnsa))
2566 debug_printf("DNS lookup of %.256s (SRV) requested AD, but got AA\n", host->name);
2567
2568 if (dnssec_request)
2569 {
2570 if (dns_is_secure(&dnsa))
2571 { dnssec = DS_YES; lookup_dnssec_authenticated = US"yes"; }
2572 else
2573 { dnssec = DS_NO; lookup_dnssec_authenticated = US"no"; }
2574 }
2575
2576 if (temp_fully_qualified_name != buffer && fully_qualified_name != NULL)
2577 *fully_qualified_name = temp_fully_qualified_name + prefix_length;
2578
2579 /* On DNS failures, we give the "try again" error unless the domain is
2580 listed as one for which we continue. */
2581
2582 if (rc == DNS_SUCCEED && dnssec_require && !dns_is_secure(&dnsa))
2583 {
2584 log_write(L_host_lookup_failed, LOG_MAIN,
2585 "dnssec fail on SRV for %.256s", host->name);
2586 rc = DNS_FAIL;
2587 }
2588 if (rc == DNS_FAIL || rc == DNS_AGAIN)
2589 {
2590 #ifndef STAND_ALONE
2591 if (match_isinlist(host->name, CUSS &srv_fail_domains, 0, NULL, NULL,
2592 MCL_DOMAIN, TRUE, NULL) != OK)
2593 #endif
2594 { yield = HOST_FIND_AGAIN; goto out; }
2595 DEBUG(D_host_lookup) debug_printf("DNS_%s treated as DNS_NODATA "
2596 "(domain in srv_fail_domains)\n", (rc == DNS_FAIL)? "FAIL":"AGAIN");
2597 }
2598 }
2599
2600 /* If we did not find any SRV records, search the DNS for MX records, if
2601 requested to do so. If the result is DNS_NOMATCH, it means there is no such
2602 domain, and there's no point in going on to look for address records with the
2603 same domain. The result will be DNS_NODATA if the domain exists but has no MX
2604 records. On DNS failures, we give the "try again" error unless the domain is
2605 listed as one for which we continue. */
2606
2607 if (rc != DNS_SUCCEED && (whichrrs & HOST_FIND_BY_MX) != 0)
2608 {
2609 ind_type = T_MX;
2610 dnssec = DS_UNK;
2611 lookup_dnssec_authenticated = NULL;
2612 rc = dns_lookup_timerwrap(&dnsa, host->name, ind_type, fully_qualified_name);
2613
2614 DEBUG(D_dns)
2615 if ((dnssec_request || dnssec_require)
2616 & !dns_is_secure(&dnsa)
2617 & dns_is_aa(&dnsa))
2618 debug_printf("DNS lookup of %.256s (MX) requested AD, but got AA\n", host->name);
2619
2620 if (dnssec_request)
2621 {
2622 if (dns_is_secure(&dnsa))
2623 {
2624 DEBUG(D_host_lookup) debug_printf("%s MX DNSSEC\n", host->name);
2625 dnssec = DS_YES; lookup_dnssec_authenticated = US"yes";
2626 }
2627 else
2628 {
2629 dnssec = DS_NO; lookup_dnssec_authenticated = US"no";
2630 }
2631 }
2632
2633 switch (rc)
2634 {
2635 case DNS_NOMATCH:
2636 yield = HOST_FIND_FAILED; goto out;
2637
2638 case DNS_SUCCEED:
2639 if (!dnssec_require || dns_is_secure(&dnsa))
2640 break;
2641 log_write(L_host_lookup_failed, LOG_MAIN,
2642 "dnssec fail on MX for %.256s", host->name);
2643 rc = DNS_FAIL;
2644 /*FALLTHROUGH*/
2645
2646 case DNS_FAIL:
2647 case DNS_AGAIN:
2648 #ifndef STAND_ALONE
2649 if (match_isinlist(host->name, CUSS &mx_fail_domains, 0, NULL, NULL,
2650 MCL_DOMAIN, TRUE, NULL) != OK)
2651 #endif
2652 { yield = HOST_FIND_AGAIN; goto out; }
2653 DEBUG(D_host_lookup) debug_printf("DNS_%s treated as DNS_NODATA "
2654 "(domain in mx_fail_domains)\n", (rc == DNS_FAIL)? "FAIL":"AGAIN");
2655 break;
2656 }
2657 }
2658
2659 /* If we haven't found anything yet, and we are requested to do so, try for an
2660 A or AAAA record. If we find it (or them) check to see that it isn't the local
2661 host. */
2662
2663 if (rc != DNS_SUCCEED)
2664 {
2665 if ((whichrrs & HOST_FIND_BY_A) == 0)
2666 {
2667 DEBUG(D_host_lookup) debug_printf("Address records are not being sought\n");
2668 yield = HOST_FIND_FAILED;
2669 goto out;
2670 }
2671
2672 last = host; /* End of local chainlet */
2673 host->mx = MX_NONE;
2674 host->port = PORT_NONE;
2675 host->dnssec = DS_UNK;
2676 lookup_dnssec_authenticated = NULL;
2677 rc = set_address_from_dns(host, &last, ignore_target_hosts, FALSE,
2678 fully_qualified_name, dnssec_request, dnssec_require);
2679
2680 /* If one or more address records have been found, check that none of them
2681 are local. Since we know the host items all have their IP addresses
2682 inserted, host_scan_for_local_hosts() can only return HOST_FOUND or
2683 HOST_FOUND_LOCAL. We do not need to scan for duplicate IP addresses here,
2684 because set_address_from_dns() removes them. */
2685
2686 if (rc == HOST_FOUND)
2687 rc = host_scan_for_local_hosts(host, &last, removed);
2688 else
2689 if (rc == HOST_IGNORED) rc = HOST_FIND_FAILED; /* No special action */
2690
2691 DEBUG(D_host_lookup)
2692 {
2693 host_item *h;
2694 if (host->address != NULL)
2695 {
2696 if (fully_qualified_name != NULL)
2697 debug_printf("fully qualified name = %s\n", *fully_qualified_name);
2698 for (h = host; h != last->next; h = h->next)
2699 debug_printf("%s %s mx=%d sort=%d %s\n", h->name,
2700 (h->address == NULL)? US"<null>" : h->address, h->mx, h->sort_key,
2701 (h->status >= hstatus_unusable)? US"*" : US"");
2702 }
2703 }
2704
2705 yield = rc;
2706 goto out;
2707 }
2708
2709 /* We have found one or more MX or SRV records. Sort them according to
2710 precedence. Put the data for the first one into the existing host block, and
2711 insert new host_item blocks into the chain for the remainder. For equal
2712 precedences one is supposed to randomize the order. To make this happen, the
2713 sorting is actually done on the MX value * 1000 + a random number. This is put
2714 into a host field called sort_key.
2715
2716 In the case of hosts with both IPv6 and IPv4 addresses, we want to choose the
2717 IPv6 address in preference. At this stage, we don't know what kind of address
2718 the host has. We choose a random number < 500; if later we find an A record
2719 first, we add 500 to the random number. Then for any other address records, we
2720 use random numbers in the range 0-499 for AAAA records and 500-999 for A
2721 records.
2722
2723 At this point we remove any duplicates that point to the same host, retaining
2724 only the one with the lowest precedence. We cannot yet check for precedence
2725 greater than that of the local host, because that test cannot be properly done
2726 until the addresses have been found - an MX record may point to a name for this
2727 host which is not the primary hostname. */
2728
2729 last = NULL; /* Indicates that not even the first item is filled yet */
2730
2731 for (rr = dns_next_rr(&dnsa, &dnss, RESET_ANSWERS);
2732 rr != NULL;
2733 rr = dns_next_rr(&dnsa, &dnss, RESET_NEXT))
2734 {
2735 int precedence;
2736 int weight = 0; /* For SRV records */
2737 int port = PORT_NONE;
2738 uschar *s; /* MUST be unsigned for GETSHORT */
2739 uschar data[256];
2740
2741 if (rr->type != ind_type) continue;
2742 s = rr->data;
2743 GETSHORT(precedence, s); /* Pointer s is advanced */
2744
2745 /* For MX records, we use a random "weight" which causes multiple records of
2746 the same precedence to sort randomly. */
2747
2748 if (ind_type == T_MX)
2749 weight = random_number(500);
2750
2751 /* SRV records are specified with a port and a weight. The weight is used
2752 in a special algorithm. However, to start with, we just use it to order the
2753 records of equal priority (precedence). */
2754
2755 else
2756 {
2757 GETSHORT(weight, s);
2758 GETSHORT(port, s);
2759 }
2760
2761 /* Get the name of the host pointed to. */
2762
2763 (void)dn_expand(dnsa.answer, dnsa.answer + dnsa.answerlen, s,
2764 (DN_EXPAND_ARG4_TYPE)data, sizeof(data));
2765
2766 /* Check that we haven't already got this host on the chain; if we have,
2767 keep only the lower precedence. This situation shouldn't occur, but you
2768 never know what junk might get into the DNS (and this case has been seen on
2769 more than one occasion). */
2770
2771 if (last != NULL) /* This is not the first record */
2772 {
2773 host_item *prev = NULL;
2774
2775 for (h = host; h != last->next; prev = h, h = h->next)
2776 {
2777 if (strcmpic(h->name, data) == 0)
2778 {
2779 DEBUG(D_host_lookup)
2780 debug_printf("discarded duplicate host %s (MX=%d)\n", data,
2781 (precedence > h->mx)? precedence : h->mx);
2782 if (precedence >= h->mx) goto NEXT_MX_RR; /* Skip greater precedence */
2783 if (h == host) /* Override first item */
2784 {
2785 h->mx = precedence;
2786 host->sort_key = precedence * 1000 + weight;
2787 goto NEXT_MX_RR;
2788 }
2789
2790 /* Unwanted host item is not the first in the chain, so we can get
2791 get rid of it by cutting it out. */
2792
2793 prev->next = h->next;
2794 if (h == last) last = prev;
2795 break;
2796 }
2797 }
2798 }
2799
2800 /* If this is the first MX or SRV record, put the data into the existing host
2801 block. Otherwise, add a new block in the correct place; if it has to be
2802 before the first block, copy the first block's data to a new second block. */
2803
2804 if (last == NULL)
2805 {
2806 host->name = string_copy_dnsdomain(data);
2807 host->address = NULL;
2808 host->port = port;
2809 host->mx = precedence;
2810 host->sort_key = precedence * 1000 + weight;
2811 host->status = hstatus_unknown;
2812 host->why = hwhy_unknown;
2813 host->dnssec = dnssec;
2814 last = host;
2815 }
2816
2817 /* Make a new host item and seek the correct insertion place */
2818
2819 else
2820 {
2821 int sort_key = precedence * 1000 + weight;
2822 host_item *next = store_get(sizeof(host_item));
2823 next->name = string_copy_dnsdomain(data);
2824 next->address = NULL;
2825 next->port = port;
2826 next->mx = precedence;
2827 next->sort_key = sort_key;
2828 next->status = hstatus_unknown;
2829 next->why = hwhy_unknown;
2830 next->dnssec = dnssec;
2831 next->last_try = 0;
2832
2833 /* Handle the case when we have to insert before the first item. */
2834
2835 if (sort_key < host->sort_key)
2836 {
2837 host_item htemp;
2838 htemp = *host;
2839 *host = *next;
2840 *next = htemp;
2841 host->next = next;
2842 if (last == host) last = next;
2843 }
2844
2845 /* Else scan down the items we have inserted as part of this exercise;
2846 don't go further. */
2847
2848 else
2849 {
2850 for (h = host; h != last; h = h->next)
2851 {
2852 if (sort_key < h->next->sort_key)
2853 {
2854 next->next = h->next;
2855 h->next = next;
2856 break;
2857 }
2858 }
2859
2860 /* Join on after the last host item that's part of this
2861 processing if we haven't stopped sooner. */
2862
2863 if (h == last)
2864 {
2865 next->next = last->next;
2866 last->next = next;
2867 last = next;
2868 }
2869 }
2870 }
2871
2872 NEXT_MX_RR: continue;
2873 }
2874
2875 /* If the list of hosts was obtained from SRV records, there are two things to
2876 do. First, if there is only one host, and it's name is ".", it means there is
2877 no SMTP service at this domain. Otherwise, we have to sort the hosts of equal
2878 priority according to their weights, using an algorithm that is defined in RFC
2879 2782. The hosts are currently sorted by priority and weight. For each priority
2880 group we have to pick off one host and put it first, and then repeat for any
2881 remaining in the same priority group. */
2882
2883 if (ind_type == T_SRV)
2884 {
2885 host_item **pptr;
2886
2887 if (host == last && host->name[0] == 0)
2888 {
2889 DEBUG(D_host_lookup) debug_printf("the single SRV record is \".\"\n");
2890 yield = HOST_FIND_FAILED;
2891 goto out;
2892 }
2893
2894 DEBUG(D_host_lookup)
2895 {
2896 debug_printf("original ordering of hosts from SRV records:\n");
2897 for (h = host; h != last->next; h = h->next)
2898 debug_printf(" %s P=%d W=%d\n", h->name, h->mx, h->sort_key % 1000);
2899 }
2900
2901 for (pptr = &host, h = host; h != last; pptr = &(h->next), h = h->next)
2902 {
2903 int sum = 0;
2904 host_item *hh;
2905
2906 /* Find the last following host that has the same precedence. At the same
2907 time, compute the sum of the weights and the running totals. These can be
2908 stored in the sort_key field. */
2909
2910 for (hh = h; hh != last; hh = hh->next)
2911 {
2912 int weight = hh->sort_key % 1000; /* was precedence * 1000 + weight */
2913 sum += weight;
2914 hh->sort_key = sum;
2915 if (hh->mx != hh->next->mx) break;
2916 }
2917
2918 /* If there's more than one host at this precedence (priority), we need to
2919 pick one to go first. */
2920
2921 if (hh != h)
2922 {
2923 host_item *hhh;
2924 host_item **ppptr;
2925 int randomizer = random_number(sum + 1);
2926
2927 for (ppptr = pptr, hhh = h;
2928 hhh != hh;
2929 ppptr = &(hhh->next), hhh = hhh->next)
2930 {
2931 if (hhh->sort_key >= randomizer) break;
2932 }
2933
2934 /* hhh now points to the host that should go first; ppptr points to the
2935 place that points to it. Unfortunately, if the start of the minilist is
2936 the start of the entire list, we can't just swap the items over, because
2937 we must not change the value of host, since it is passed in from outside.
2938 One day, this could perhaps be changed.
2939
2940 The special case is fudged by putting the new item *second* in the chain,
2941 and then transferring the data between the first and second items. We
2942 can't just swap the first and the chosen item, because that would mean
2943 that an item with zero weight might no longer be first. */
2944
2945 if (hhh != h)
2946 {
2947 *ppptr = hhh->next; /* Cuts it out of the chain */
2948
2949 if (h == host)
2950 {
2951 host_item temp = *h;
2952 *h = *hhh;
2953 *hhh = temp;
2954 hhh->next = temp.next;
2955 h->next = hhh;
2956 }
2957
2958 else
2959 {
2960 hhh->next = h; /* The rest of the chain follows it */
2961 *pptr = hhh; /* It takes the place of h */
2962 h = hhh; /* It's now the start of this minilist */
2963 }
2964 }
2965 }
2966
2967 /* A host has been chosen to be first at this priority and h now points
2968 to this host. There may be others at the same priority, or others at a
2969 different priority. Before we leave this host, we need to put back a sort
2970 key of the traditional MX kind, in case this host is multihomed, because
2971 the sort key is used for ordering the multiple IP addresses. We do not need
2972 to ensure that these new sort keys actually reflect the order of the hosts,
2973 however. */
2974
2975 h->sort_key = h->mx * 1000 + random_number(500);
2976 } /* Move on to the next host */
2977 }
2978
2979 /* Now we have to find IP addresses for all the hosts. We have ensured above
2980 that the names in all the host items are unique. Before release 4.61 we used to
2981 process records from the additional section in the DNS packet that returned the
2982 MX or SRV records. However, a DNS name server is free to drop any resource
2983 records from the additional section. In theory, this has always been a
2984 potential problem, but it is exacerbated by the advent of IPv6. If a host had
2985 several IPv4 addresses and some were not in the additional section, at least
2986 Exim would try the others. However, if a host had both IPv4 and IPv6 addresses
2987 and all the IPv4 (say) addresses were absent, Exim would try only for a IPv6
2988 connection, and never try an IPv4 address. When there was only IPv4
2989 connectivity, this was a disaster that did in practice occur.
2990
2991 So, from release 4.61 onwards, we always search for A and AAAA records
2992 explicitly. The names shouldn't point to CNAMES, but we use the general lookup
2993 function that handles them, just in case. If any lookup gives a soft error,
2994 change the default yield.
2995
2996 For these DNS lookups, we must disable qualify_single and search_parents;
2997 otherwise invalid host names obtained from MX or SRV records can cause trouble
2998 if they happen to match something local. */
2999
3000 yield = HOST_FIND_FAILED; /* Default yield */
3001 dns_init(FALSE, FALSE, /* Disable qualify_single and search_parents */
3002 dnssec_request || dnssec_require);
3003
3004 for (h = host; h != last->next; h = h->next)
3005 {
3006 if (h->address != NULL) continue; /* Inserted by a multihomed host */
3007 rc = set_address_from_dns(h, &last, ignore_target_hosts, allow_mx_to_ip,
3008 NULL, dnssec_request, dnssec_require);
3009 if (rc != HOST_FOUND)
3010 {
3011 h->status = hstatus_unusable;
3012 if (rc == HOST_FIND_AGAIN)
3013 {
3014 yield = rc;
3015 h->why = hwhy_deferred;
3016 }
3017 else
3018 h->why = (rc == HOST_IGNORED)? hwhy_ignored : hwhy_failed;
3019 }
3020 }
3021
3022 /* Scan the list for any hosts that are marked unusable because they have
3023 been explicitly ignored, and remove them from the list, as if they did not
3024 exist. If we end up with just a single, ignored host, flatten its fields as if
3025 nothing was found. */
3026
3027 if (ignore_target_hosts != NULL)
3028 {
3029 host_item *prev = NULL;
3030 for (h = host; h != last->next; h = h->next)
3031 {
3032 REDO:
3033 if (h->why != hwhy_ignored) /* Non ignored host, just continue */
3034 prev = h;
3035 else if (prev == NULL) /* First host is ignored */
3036 {
3037 if (h != last) /* First is not last */
3038 {
3039 if (h->next == last) last = h; /* Overwrite it with next */
3040 *h = *(h->next); /* and reprocess it. */
3041 goto REDO; /* C should have redo, like Perl */
3042 }
3043 }
3044 else /* Ignored host is not first - */
3045 { /* cut it out */
3046 prev->next = h->next;
3047 if (h == last) last = prev;
3048 }
3049 }
3050
3051 if (host->why == hwhy_ignored) host->address = NULL;
3052 }
3053
3054 /* There is still one complication in the case of IPv6. Although the code above
3055 arranges that IPv6 addresses take precedence over IPv4 addresses for multihomed
3056 hosts, it doesn't do this for addresses that apply to different hosts with the
3057 same MX precedence, because the sorting on MX precedence happens first. So we
3058 have to make another pass to check for this case. We ensure that, within a
3059 single MX preference value, IPv6 addresses come first. This can separate the
3060 addresses of a multihomed host, but that should not matter. */
3061
3062 #if HAVE_IPV6
3063 if (h != last && !disable_ipv6)
3064 {
3065 for (h = host; h != last; h = h->next)
3066 {
3067 host_item temp;
3068 host_item *next = h->next;
3069 if (h->mx != next->mx || /* If next is different MX */
3070 h->address == NULL || /* OR this one is unset */
3071 Ustrchr(h->address, ':') != NULL || /* OR this one is IPv6 */
3072 (next->address != NULL &&
3073 Ustrchr(next->address, ':') == NULL)) /* OR next is IPv4 */
3074 continue; /* move on to next */
3075 temp = *h; /* otherwise, swap */
3076 temp.next = next->next;
3077 *h = *next;
3078 h->next = next;
3079 *next = temp;
3080 }
3081 }
3082 #endif
3083
3084 /* Remove any duplicate IP addresses and then scan the list of hosts for any
3085 whose IP addresses are on the local host. If any are found, all hosts with the
3086 same or higher MX values are removed. However, if the local host has the lowest
3087 numbered MX, then HOST_FOUND_LOCAL is returned. Otherwise, if at least one host
3088 with an IP address is on the list, HOST_FOUND is returned. Otherwise,
3089 HOST_FIND_FAILED is returned, but in this case do not update the yield, as it
3090 might have been set to HOST_FIND_AGAIN just above here. If not, it will already
3091 be HOST_FIND_FAILED. */
3092
3093 host_remove_duplicates(host, &last);
3094 rc = host_scan_for_local_hosts(host, &last, removed);
3095 if (rc != HOST_FIND_FAILED) yield = rc;
3096
3097 DEBUG(D_host_lookup)
3098 {
3099 if (fully_qualified_name != NULL)
3100 debug_printf("fully qualified name = %s\n", *fully_qualified_name);
3101 debug_printf("host_find_bydns yield = %s (%d); returned hosts:\n",
3102 (yield == HOST_FOUND)? "HOST_FOUND" :
3103 (yield == HOST_FOUND_LOCAL)? "HOST_FOUND_LOCAL" :
3104 (yield == HOST_FIND_AGAIN)? "HOST_FIND_AGAIN" :
3105 (yield == HOST_FIND_FAILED)? "HOST_FIND_FAILED" : "?",
3106 yield);
3107 for (h = host; h != last->next; h = h->next)
3108 {
3109 debug_printf(" %s %s MX=%d %s", h->name,
3110 !h->address ? US"<null>" : h->address, h->mx,
3111 h->dnssec == DS_YES ? US"DNSSEC " : US"");
3112 if (h->port != PORT_NONE) debug_printf("port=%d ", h->port);
3113 if (h->status >= hstatus_unusable) debug_printf("*");
3114 debug_printf("\n");
3115 }
3116 }
3117
3118 out:
3119
3120 dns_init(FALSE, FALSE, FALSE); /* clear the dnssec bit for getaddrbyname */
3121 return yield;
3122 }
3123
3124 /*************************************************
3125 **************************************************
3126 * Stand-alone test program *
3127 **************************************************
3128 *************************************************/
3129
3130 #ifdef STAND_ALONE
3131
3132 int main(int argc, char **cargv)
3133 {
3134 host_item h;
3135 int whichrrs = HOST_FIND_BY_MX | HOST_FIND_BY_A;
3136 BOOL byname = FALSE;
3137 BOOL qualify_single = TRUE;
3138 BOOL search_parents = FALSE;
3139 BOOL request_dnssec = FALSE;
3140 BOOL require_dnssec = FALSE;
3141 uschar **argv = USS cargv;
3142 uschar buffer[256];
3143
3144 disable_ipv6 = FALSE;
3145 primary_hostname = US"";
3146 store_pool = POOL_MAIN;
3147 debug_selector = D_host_lookup|D_interface;
3148 debug_file = stdout;
3149 debug_fd = fileno(debug_file);
3150
3151 printf("Exim stand-alone host functions test\n");
3152
3153 host_find_interfaces();
3154 debug_selector = D_host_lookup | D_dns;
3155
3156 if (argc > 1) primary_hostname = argv[1];
3157
3158 /* So that debug level changes can be done first */
3159
3160 dns_init(qualify_single, search_parents, FALSE);
3161
3162 printf("Testing host lookup\n");
3163 printf("> ");
3164 while (Ufgets(buffer, 256, stdin) != NULL)
3165 {
3166 int rc;
3167 int len = Ustrlen(buffer);
3168 uschar *fully_qualified_name;
3169
3170 while (len > 0 && isspace(buffer[len-1])) len--;
3171 buffer[len] = 0;
3172
3173 if (Ustrcmp(buffer, "q") == 0) break;
3174
3175 if (Ustrcmp(buffer, "byname") == 0) byname = TRUE;
3176 else if (Ustrcmp(buffer, "no_byname") == 0) byname = FALSE;
3177 else if (Ustrcmp(buffer, "a_only") == 0) whichrrs = HOST_FIND_BY_A;
3178 else if (Ustrcmp(buffer, "mx_only") == 0) whichrrs = HOST_FIND_BY_MX;
3179 else if (Ustrcmp(buffer, "srv_only") == 0) whichrrs = HOST_FIND_BY_SRV;
3180 else if (Ustrcmp(buffer, "srv+a") == 0)
3181 whichrrs = HOST_FIND_BY_SRV | HOST_FIND_BY_A;
3182 else if (Ustrcmp(buffer, "srv+mx") == 0)
3183 whichrrs = HOST_FIND_BY_SRV | HOST_FIND_BY_MX;
3184 else if (Ustrcmp(buffer, "srv+mx+a") == 0)
3185 whichrrs = HOST_FIND_BY_SRV | HOST_FIND_BY_MX | HOST_FIND_BY_A;
3186 else if (Ustrcmp(buffer, "qualify_single") == 0) qualify_single = TRUE;
3187 else if (Ustrcmp(buffer, "no_qualify_single") == 0) qualify_single = FALSE;
3188 else if (Ustrcmp(buffer, "search_parents") == 0) search_parents = TRUE;
3189 else if (Ustrcmp(buffer, "no_search_parents") == 0) search_parents = FALSE;
3190 else if (Ustrcmp(buffer, "request_dnssec") == 0) request_dnssec = TRUE;
3191 else if (Ustrcmp(buffer, "no_request_dnssec") == 0) request_dnssec = FALSE;
3192 else if (Ustrcmp(buffer, "require_dnssec") == 0) require_dnssec = TRUE;
3193 else if (Ustrcmp(buffer, "no_reqiret_dnssec") == 0) require_dnssec = FALSE;
3194 else if (Ustrcmp(buffer, "test_harness") == 0)
3195 running_in_test_harness = !running_in_test_harness;
3196 else if (Ustrcmp(buffer, "ipv6") == 0) disable_ipv6 = !disable_ipv6;
3197 else if (Ustrcmp(buffer, "res_debug") == 0)
3198 {
3199 _res.options ^= RES_DEBUG;
3200 }
3201 else if (Ustrncmp(buffer, "retrans", 7) == 0)
3202 {
3203 (void)sscanf(CS(buffer+8), "%d", &dns_retrans);
3204 _res.retrans = dns_retrans;
3205 }
3206 else if (Ustrncmp(buffer, "retry", 5) == 0)
3207 {
3208 (void)sscanf(CS(buffer+6), "%d", &dns_retry);
3209 _res.retry = dns_retry;
3210 }
3211 else
3212 {
3213 int flags = whichrrs;
3214 dnssec_domains d;
3215
3216 h.name = buffer;
3217 h.next = NULL;
3218 h.mx = MX_NONE;
3219 h.port = PORT_NONE;
3220 h.status = hstatus_unknown;
3221 h.why = hwhy_unknown;
3222 h.address = NULL;
3223
3224 if (qualify_single) flags |= HOST_FIND_QUALIFY_SINGLE;
3225 if (search_parents) flags |= HOST_FIND_SEARCH_PARENTS;
3226
3227 d.request = request_dnssec ? &h.name : NULL;
3228 d.require = require_dnssec ? &h.name : NULL;
3229
3230 rc = byname
3231 ? host_find_byname(&h, NULL, flags, &fully_qualified_name, TRUE)
3232 : host_find_bydns(&h, NULL, flags, US"smtp", NULL, NULL,
3233 &d, &fully_qualified_name, NULL);
3234
3235 if (rc == HOST_FIND_FAILED) printf("Failed\n");
3236 else if (rc == HOST_FIND_AGAIN) printf("Again\n");
3237 else if (rc == HOST_FOUND_LOCAL) printf("Local\n");
3238 }
3239
3240 printf("\n> ");
3241 }
3242
3243 printf("Testing host_aton\n");
3244 printf("> ");
3245 while (Ufgets(buffer, 256, stdin) != NULL)
3246 {
3247 int i;
3248 int x[4];
3249 int len = Ustrlen(buffer);
3250
3251 while (len > 0 && isspace(buffer[len-1])) len--;
3252 buffer[len] = 0;
3253
3254 if (Ustrcmp(buffer, "q") == 0) break;
3255
3256 len = host_aton(buffer, x);
3257 printf("length = %d ", len);
3258 for (i = 0; i < len; i++)
3259 {
3260 printf("%04x ", (x[i] >> 16) & 0xffff);
3261 printf("%04x ", x[i] & 0xffff);
3262 }
3263 printf("\n> ");
3264 }
3265
3266 printf("\n");
3267
3268 printf("Testing host_name_lookup\n");
3269 printf("> ");
3270 while (Ufgets(buffer, 256, stdin) != NULL)
3271 {
3272 int len = Ustrlen(buffer);
3273 while (len > 0 && isspace(buffer[len-1])) len--;
3274 buffer[len] = 0;
3275 if (Ustrcmp(buffer, "q") == 0) break;
3276 sender_host_address = buffer;
3277 sender_host_name = NULL;
3278 sender_host_aliases = NULL;
3279 host_lookup_msg = US"";
3280 host_lookup_failed = FALSE;
3281 if (host_name_lookup() == FAIL) /* Debug causes printing */
3282 printf("Lookup failed:%s\n", host_lookup_msg);
3283 printf("\n> ");
3284 }
3285
3286 printf("\n");
3287
3288 return 0;
3289 }
3290 #endif /* STAND_ALONE */
3291
3292 /* vi: aw ai sw=2
3293 */
3294 /* End of host.c */