Change host_lookup re-forward from byname to bydns; checking DNSSEC
[exim.git] / src / src / host.c
1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
4
5 /* Copyright (c) University of Cambridge 1995 - 2012 */
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 ((log_extra_selector & LX_incoming_port) == 0 || 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 ((log_extra_selector & LX_incoming_interface) != 0 &&
699 interface_address != NULL)
700 iface = string_sprintf(" I=[%s]:%d", interface_address, interface_port);
701 if (sender_ident == NULL)
702 (void)string_format(big_buffer, big_buffer_size, "%s%s%s",
703 flag, sender_fullhost, iface);
704 else
705 (void)string_format(big_buffer, big_buffer_size, "%s%s%s U=%s",
706 flag, sender_fullhost, iface, sender_ident);
707 }
708 return big_buffer;
709 }
710
711 #endif /* STAND_ALONE */
712
713
714
715
716 /*************************************************
717 * Build list of local interfaces *
718 *************************************************/
719
720 /* This function interprets the contents of the local_interfaces or
721 extra_local_interfaces options, and creates an ip_address_item block for each
722 item on the list. There is no special interpretation of any IP addresses; in
723 particular, 0.0.0.0 and ::0 are returned without modification. If any address
724 includes a port, it is set in the block. Otherwise the port value is set to
725 zero.
726
727 Arguments:
728 list the list
729 name the name of the option being expanded
730
731 Returns: a chain of ip_address_items, each containing to a textual
732 version of an IP address, and a port number (host order) or
733 zero if no port was given with the address
734 */
735
736 ip_address_item *
737 host_build_ifacelist(const uschar *list, uschar *name)
738 {
739 int sep = 0;
740 uschar *s;
741 uschar buffer[64];
742 ip_address_item *yield = NULL;
743 ip_address_item *last = NULL;
744 ip_address_item *next;
745
746 while ((s = string_nextinlist(&list, &sep, buffer, sizeof(buffer))) != NULL)
747 {
748 int ipv;
749 int port = host_address_extract_port(s); /* Leaves just the IP address */
750 if ((ipv = string_is_ip_address(s, NULL)) == 0)
751 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "Malformed IP address \"%s\" in %s",
752 s, name);
753
754 /* Skip IPv6 addresses if IPv6 is disabled. */
755
756 if (disable_ipv6 && ipv == 6) continue;
757
758 /* This use of strcpy() is OK because we have checked that s is a valid IP
759 address above. The field in the ip_address_item is large enough to hold an
760 IPv6 address. */
761
762 next = store_get(sizeof(ip_address_item));
763 next->next = NULL;
764 Ustrcpy(next->address, s);
765 next->port = port;
766 next->v6_include_v4 = FALSE;
767
768 if (yield == NULL) yield = last = next; else
769 {
770 last->next = next;
771 last = next;
772 }
773 }
774
775 return yield;
776 }
777
778
779
780
781
782 /*************************************************
783 * Find addresses on local interfaces *
784 *************************************************/
785
786 /* This function finds the addresses of local IP interfaces. These are used
787 when testing for routing to the local host. As the function may be called more
788 than once, the list is preserved in permanent store, pointed to by a static
789 variable, to save doing the work more than once per process.
790
791 The generic list of interfaces is obtained by calling host_build_ifacelist()
792 for local_interfaces and extra_local_interfaces. This list scanned to remove
793 duplicates (which may exist with different ports - not relevant here). If
794 either of the wildcard IP addresses (0.0.0.0 and ::0) are encountered, they are
795 replaced by the appropriate (IPv4 or IPv6) list of actual local interfaces,
796 obtained from os_find_running_interfaces().
797
798 Arguments: none
799 Returns: a chain of ip_address_items, each containing to a textual
800 version of an IP address; the port numbers are not relevant
801 */
802
803
804 /* First, a local subfunction to add an interface to a list in permanent store,
805 but only if there isn't a previous copy of that address on the list. */
806
807 static ip_address_item *
808 add_unique_interface(ip_address_item *list, ip_address_item *ipa)
809 {
810 ip_address_item *ipa2;
811 for (ipa2 = list; ipa2 != NULL; ipa2 = ipa2->next)
812 if (Ustrcmp(ipa2->address, ipa->address) == 0) return list;
813 ipa2 = store_get_perm(sizeof(ip_address_item));
814 *ipa2 = *ipa;
815 ipa2->next = list;
816 return ipa2;
817 }
818
819
820 /* This is the globally visible function */
821
822 ip_address_item *
823 host_find_interfaces(void)
824 {
825 ip_address_item *running_interfaces = NULL;
826
827 if (local_interface_data == NULL)
828 {
829 void *reset_item = store_get(0);
830 ip_address_item *dlist = host_build_ifacelist(CUS local_interfaces,
831 US"local_interfaces");
832 ip_address_item *xlist = host_build_ifacelist(CUS extra_local_interfaces,
833 US"extra_local_interfaces");
834 ip_address_item *ipa;
835
836 if (dlist == NULL) dlist = xlist; else
837 {
838 for (ipa = dlist; ipa->next != NULL; ipa = ipa->next);
839 ipa->next = xlist;
840 }
841
842 for (ipa = dlist; ipa != NULL; ipa = ipa->next)
843 {
844 if (Ustrcmp(ipa->address, "0.0.0.0") == 0 ||
845 Ustrcmp(ipa->address, "::0") == 0)
846 {
847 ip_address_item *ipa2;
848 BOOL ipv6 = ipa->address[0] == ':';
849 if (running_interfaces == NULL)
850 running_interfaces = os_find_running_interfaces();
851 for (ipa2 = running_interfaces; ipa2 != NULL; ipa2 = ipa2->next)
852 {
853 if ((Ustrchr(ipa2->address, ':') != NULL) == ipv6)
854 local_interface_data = add_unique_interface(local_interface_data,
855 ipa2);
856 }
857 }
858 else
859 {
860 local_interface_data = add_unique_interface(local_interface_data, ipa);
861 DEBUG(D_interface)
862 {
863 debug_printf("Configured local interface: address=%s", ipa->address);
864 if (ipa->port != 0) debug_printf(" port=%d", ipa->port);
865 debug_printf("\n");
866 }
867 }
868 }
869 store_reset(reset_item);
870 }
871
872 return local_interface_data;
873 }
874
875
876
877
878
879 /*************************************************
880 * Convert network IP address to text *
881 *************************************************/
882
883 /* Given an IPv4 or IPv6 address in binary, convert it to a text
884 string and return the result in a piece of new store. The address can
885 either be given directly, or passed over in a sockaddr structure. Note
886 that this isn't the converse of host_aton() because of byte ordering
887 differences. See host_nmtoa() below.
888
889 Arguments:
890 type if < 0 then arg points to a sockaddr, else
891 either AF_INET or AF_INET6
892 arg points to a sockaddr if type is < 0, or
893 points to an IPv4 address (32 bits), or
894 points to an IPv6 address (128 bits),
895 in both cases, in network byte order
896 buffer if NULL, the result is returned in gotten store;
897 else points to a buffer to hold the answer
898 portptr points to where to put the port number, if non NULL; only
899 used when type < 0
900
901 Returns: pointer to character string
902 */
903
904 uschar *
905 host_ntoa(int type, const void *arg, uschar *buffer, int *portptr)
906 {
907 uschar *yield;
908
909 /* The new world. It is annoying that we have to fish out the address from
910 different places in the block, depending on what kind of address it is. It
911 is also a pain that inet_ntop() returns a const uschar *, whereas the IPv4
912 function inet_ntoa() returns just uschar *, and some picky compilers insist
913 on warning if one assigns a const uschar * to a uschar *. Hence the casts. */
914
915 #if HAVE_IPV6
916 uschar addr_buffer[46];
917 if (type < 0)
918 {
919 int family = ((struct sockaddr *)arg)->sa_family;
920 if (family == AF_INET6)
921 {
922 struct sockaddr_in6 *sk = (struct sockaddr_in6 *)arg;
923 yield = (uschar *)inet_ntop(family, &(sk->sin6_addr), CS addr_buffer,
924 sizeof(addr_buffer));
925 if (portptr != NULL) *portptr = ntohs(sk->sin6_port);
926 }
927 else
928 {
929 struct sockaddr_in *sk = (struct sockaddr_in *)arg;
930 yield = (uschar *)inet_ntop(family, &(sk->sin_addr), CS addr_buffer,
931 sizeof(addr_buffer));
932 if (portptr != NULL) *portptr = ntohs(sk->sin_port);
933 }
934 }
935 else
936 {
937 yield = (uschar *)inet_ntop(type, arg, CS addr_buffer, sizeof(addr_buffer));
938 }
939
940 /* If the result is a mapped IPv4 address, show it in V4 format. */
941
942 if (Ustrncmp(yield, "::ffff:", 7) == 0) yield += 7;
943
944 #else /* HAVE_IPV6 */
945
946 /* The old world */
947
948 if (type < 0)
949 {
950 yield = US inet_ntoa(((struct sockaddr_in *)arg)->sin_addr);
951 if (portptr != NULL) *portptr = ntohs(((struct sockaddr_in *)arg)->sin_port);
952 }
953 else
954 yield = US inet_ntoa(*((struct in_addr *)arg));
955 #endif
956
957 /* If there is no buffer, put the string into some new store. */
958
959 if (buffer == NULL) return string_copy(yield);
960
961 /* Callers of this function with a non-NULL buffer must ensure that it is
962 large enough to hold an IPv6 address, namely, at least 46 bytes. That's what
963 makes this use of strcpy() OK. */
964
965 Ustrcpy(buffer, yield);
966 return buffer;
967 }
968
969
970
971
972 /*************************************************
973 * Convert address text to binary *
974 *************************************************/
975
976 /* Given the textual form of an IP address, convert it to binary in an
977 array of ints. IPv4 addresses occupy one int; IPv6 addresses occupy 4 ints.
978 The result has the first byte in the most significant byte of the first int. In
979 other words, the result is not in network byte order, but in host byte order.
980 As a result, this is not the converse of host_ntoa(), which expects network
981 byte order. See host_nmtoa() below.
982
983 Arguments:
984 address points to the textual address, checked for syntax
985 bin points to an array of 4 ints
986
987 Returns: the number of ints used
988 */
989
990 int
991 host_aton(const uschar *address, int *bin)
992 {
993 int x[4];
994 int v4offset = 0;
995
996 /* Handle IPv6 address, which may end with an IPv4 address. It may also end
997 with a "scope", introduced by a percent sign. This code is NOT enclosed in #if
998 HAVE_IPV6 in order that IPv6 addresses are recognized even if IPv6 is not
999 supported. */
1000
1001 if (Ustrchr(address, ':') != NULL)
1002 {
1003 const uschar *p = address;
1004 const uschar *component[8];
1005 BOOL ipv4_ends = FALSE;
1006 int ci = 0;
1007 int nulloffset = 0;
1008 int v6count = 8;
1009 int i;
1010
1011 /* If the address starts with a colon, it will start with two colons.
1012 Just lose the first one, which will leave a null first component. */
1013
1014 if (*p == ':') p++;
1015
1016 /* Split the address into components separated by colons. The input address
1017 is supposed to be checked for syntax. There was a case where this was
1018 overlooked; to guard against that happening again, check here and crash if
1019 there are too many components. */
1020
1021 while (*p != 0 && *p != '%')
1022 {
1023 int len = Ustrcspn(p, ":%");
1024 if (len == 0) nulloffset = ci;
1025 if (ci > 7) log_write(0, LOG_MAIN|LOG_PANIC_DIE,
1026 "Internal error: invalid IPv6 address \"%s\" passed to host_aton()",
1027 address);
1028 component[ci++] = p;
1029 p += len;
1030 if (*p == ':') p++;
1031 }
1032
1033 /* If the final component contains a dot, it is a trailing v4 address.
1034 As the syntax is known to be checked, just set up for a trailing
1035 v4 address and restrict the v6 part to 6 components. */
1036
1037 if (Ustrchr(component[ci-1], '.') != NULL)
1038 {
1039 address = component[--ci];
1040 ipv4_ends = TRUE;
1041 v4offset = 3;
1042 v6count = 6;
1043 }
1044
1045 /* If there are fewer than 6 or 8 components, we have to insert some
1046 more empty ones in the middle. */
1047
1048 if (ci < v6count)
1049 {
1050 int insert_count = v6count - ci;
1051 for (i = v6count-1; i > nulloffset + insert_count; i--)
1052 component[i] = component[i - insert_count];
1053 while (i > nulloffset) component[i--] = US"";
1054 }
1055
1056 /* Now turn the components into binary in pairs and bung them
1057 into the vector of ints. */
1058
1059 for (i = 0; i < v6count; i += 2)
1060 bin[i/2] = (Ustrtol(component[i], NULL, 16) << 16) +
1061 Ustrtol(component[i+1], NULL, 16);
1062
1063 /* If there was no terminating v4 component, we are done. */
1064
1065 if (!ipv4_ends) return 4;
1066 }
1067
1068 /* Handle IPv4 address */
1069
1070 (void)sscanf(CS address, "%d.%d.%d.%d", x, x+1, x+2, x+3);
1071 bin[v4offset] = (x[0] << 24) + (x[1] << 16) + (x[2] << 8) + x[3];
1072 return v4offset+1;
1073 }
1074
1075
1076 /*************************************************
1077 * Apply mask to an IP address *
1078 *************************************************/
1079
1080 /* Mask an address held in 1 or 4 ints, with the ms bit in the ms bit of the
1081 first int, etc.
1082
1083 Arguments:
1084 count the number of ints
1085 binary points to the ints to be masked
1086 mask the count of ms bits to leave, or -1 if no masking
1087
1088 Returns: nothing
1089 */
1090
1091 void
1092 host_mask(int count, int *binary, int mask)
1093 {
1094 int i;
1095 if (mask < 0) mask = 99999;
1096 for (i = 0; i < count; i++)
1097 {
1098 int wordmask;
1099 if (mask == 0) wordmask = 0;
1100 else if (mask < 32)
1101 {
1102 wordmask = (-1) << (32 - mask);
1103 mask = 0;
1104 }
1105 else
1106 {
1107 wordmask = -1;
1108 mask -= 32;
1109 }
1110 binary[i] &= wordmask;
1111 }
1112 }
1113
1114
1115
1116
1117 /*************************************************
1118 * Convert masked IP address in ints to text *
1119 *************************************************/
1120
1121 /* We can't use host_ntoa() because it assumes the binary values are in network
1122 byte order, and these are the result of host_aton(), which puts them in ints in
1123 host byte order. Also, we really want IPv6 addresses to be in a canonical
1124 format, so we output them with no abbreviation. In a number of cases we can't
1125 use the normal colon separator in them because it terminates keys in lsearch
1126 files, so we want to use dot instead. There's an argument that specifies what
1127 to use for IPv6 addresses.
1128
1129 Arguments:
1130 count 1 or 4 (number of ints)
1131 binary points to the ints
1132 mask mask value; if < 0 don't add to result
1133 buffer big enough to hold the result
1134 sep component separator character for IPv6 addresses
1135
1136 Returns: the number of characters placed in buffer, not counting
1137 the final nul.
1138 */
1139
1140 int
1141 host_nmtoa(int count, int *binary, int mask, uschar *buffer, int sep)
1142 {
1143 int i, j;
1144 uschar *tt = buffer;
1145
1146 if (count == 1)
1147 {
1148 j = binary[0];
1149 for (i = 24; i >= 0; i -= 8)
1150 {
1151 sprintf(CS tt, "%d.", (j >> i) & 255);
1152 while (*tt) tt++;
1153 }
1154 }
1155 else
1156 {
1157 for (i = 0; i < 4; i++)
1158 {
1159 j = binary[i];
1160 sprintf(CS tt, "%04x%c%04x%c", (j >> 16) & 0xffff, sep, j & 0xffff, sep);
1161 while (*tt) tt++;
1162 }
1163 }
1164
1165 tt--; /* lose final separator */
1166
1167 if (mask < 0)
1168 *tt = 0;
1169 else
1170 {
1171 sprintf(CS tt, "/%d", mask);
1172 while (*tt) tt++;
1173 }
1174
1175 return tt - buffer;
1176 }
1177
1178
1179
1180 /*************************************************
1181 * Check port for tls_on_connect *
1182 *************************************************/
1183
1184 /* This function checks whether a given incoming port is configured for tls-
1185 on-connect. It is called from the daemon and from inetd handling. If the global
1186 option tls_on_connect is already set, all ports operate this way. Otherwise, we
1187 check the tls_on_connect_ports option for a list of ports.
1188
1189 Argument: a port number
1190 Returns: TRUE or FALSE
1191 */
1192
1193 BOOL
1194 host_is_tls_on_connect_port(int port)
1195 {
1196 int sep = 0;
1197 uschar buffer[32];
1198 const uschar *list = tls_in.on_connect_ports;
1199 uschar *s;
1200 uschar *end;
1201
1202 if (tls_in.on_connect) return TRUE;
1203
1204 while ((s = string_nextinlist(&list, &sep, buffer, sizeof(buffer))))
1205 if (Ustrtol(s, &end, 10) == port)
1206 return TRUE;
1207
1208 return FALSE;
1209 }
1210
1211
1212
1213 /*************************************************
1214 * Check whether host is in a network *
1215 *************************************************/
1216
1217 /* This function checks whether a given IP address matches a pattern that
1218 represents either a single host, or a network (using CIDR notation). The caller
1219 of this function must check the syntax of the arguments before calling it.
1220
1221 Arguments:
1222 host string representation of the ip-address to check
1223 net string representation of the network, with optional CIDR mask
1224 maskoffset offset to the / that introduces the mask in the key
1225 zero if there is no mask
1226
1227 Returns:
1228 TRUE the host is inside the network
1229 FALSE the host is NOT inside the network
1230 */
1231
1232 BOOL
1233 host_is_in_net(const uschar *host, const uschar *net, int maskoffset)
1234 {
1235 int i;
1236 int address[4];
1237 int incoming[4];
1238 int mlen;
1239 int size = host_aton(net, address);
1240 int insize;
1241
1242 /* No mask => all bits to be checked */
1243
1244 if (maskoffset == 0) mlen = 99999; /* Big number */
1245 else mlen = Uatoi(net + maskoffset + 1);
1246
1247 /* Convert the incoming address to binary. */
1248
1249 insize = host_aton(host, incoming);
1250
1251 /* Convert IPv4 addresses given in IPv6 compatible mode, which represent
1252 connections from IPv4 hosts to IPv6 hosts, that is, addresses of the form
1253 ::ffff:<v4address>, to IPv4 format. */
1254
1255 if (insize == 4 && incoming[0] == 0 && incoming[1] == 0 &&
1256 incoming[2] == 0xffff)
1257 {
1258 insize = 1;
1259 incoming[0] = incoming[3];
1260 }
1261
1262 /* No match if the sizes don't agree. */
1263
1264 if (insize != size) return FALSE;
1265
1266 /* Else do the masked comparison. */
1267
1268 for (i = 0; i < size; i++)
1269 {
1270 int mask;
1271 if (mlen == 0) mask = 0;
1272 else if (mlen < 32)
1273 {
1274 mask = (-1) << (32 - mlen);
1275 mlen = 0;
1276 }
1277 else
1278 {
1279 mask = -1;
1280 mlen -= 32;
1281 }
1282 if ((incoming[i] & mask) != (address[i] & mask)) return FALSE;
1283 }
1284
1285 return TRUE;
1286 }
1287
1288
1289
1290 /*************************************************
1291 * Scan host list for local hosts *
1292 *************************************************/
1293
1294 /* Scan through a chain of addresses and check whether any of them is the
1295 address of an interface on the local machine. If so, remove that address and
1296 any previous ones with the same MX value, and all subsequent ones (which will
1297 have greater or equal MX values) from the chain. Note: marking them as unusable
1298 is NOT the right thing to do because it causes the hosts not to be used for
1299 other domains, for which they may well be correct.
1300
1301 The hosts may be part of a longer chain; we only process those between the
1302 initial pointer and the "last" pointer.
1303
1304 There is also a list of "pseudo-local" host names which are checked against the
1305 host names. Any match causes that host item to be treated the same as one which
1306 matches a local IP address.
1307
1308 If the very first host is a local host, then all MX records had a precedence
1309 greater than or equal to that of the local host. Either there's a problem in
1310 the DNS, or an apparently remote name turned out to be an abbreviation for the
1311 local host. Give a specific return code, and let the caller decide what to do.
1312 Otherwise, give a success code if at least one host address has been found.
1313
1314 Arguments:
1315 host pointer to the first host in the chain
1316 lastptr pointer to pointer to the last host in the chain (may be updated)
1317 removed if not NULL, set TRUE if some local addresses were removed
1318 from the list
1319
1320 Returns:
1321 HOST_FOUND if there is at least one host with an IP address on the chain
1322 and an MX value less than any MX value associated with the
1323 local host
1324 HOST_FOUND_LOCAL if a local host is among the lowest-numbered MX hosts; when
1325 the host addresses were obtained from A records or
1326 gethostbyname(), the MX values are set to -1.
1327 HOST_FIND_FAILED if no valid hosts with set IP addresses were found
1328 */
1329
1330 int
1331 host_scan_for_local_hosts(host_item *host, host_item **lastptr, BOOL *removed)
1332 {
1333 int yield = HOST_FIND_FAILED;
1334 host_item *last = *lastptr;
1335 host_item *prev = NULL;
1336 host_item *h;
1337
1338 if (removed != NULL) *removed = FALSE;
1339
1340 if (local_interface_data == NULL) local_interface_data = host_find_interfaces();
1341
1342 for (h = host; h != last->next; h = h->next)
1343 {
1344 #ifndef STAND_ALONE
1345 if (hosts_treat_as_local != NULL)
1346 {
1347 int rc;
1348 const uschar *save = deliver_domain;
1349 deliver_domain = h->name; /* set $domain */
1350 rc = match_isinlist(string_copylc(h->name), CUSS &hosts_treat_as_local, 0,
1351 &domainlist_anchor, NULL, MCL_DOMAIN, TRUE, NULL);
1352 deliver_domain = save;
1353 if (rc == OK) goto FOUND_LOCAL;
1354 }
1355 #endif
1356
1357 /* It seems that on many operating systems, 0.0.0.0 is treated as a synonym
1358 for 127.0.0.1 and refers to the local host. We therefore force it always to
1359 be treated as local. */
1360
1361 if (h->address != NULL)
1362 {
1363 ip_address_item *ip;
1364 if (Ustrcmp(h->address, "0.0.0.0") == 0) goto FOUND_LOCAL;
1365 for (ip = local_interface_data; ip != NULL; ip = ip->next)
1366 if (Ustrcmp(h->address, ip->address) == 0) goto FOUND_LOCAL;
1367 yield = HOST_FOUND; /* At least one remote address has been found */
1368 }
1369
1370 /* Update prev to point to the last host item before any that have
1371 the same MX value as the one we have just considered. */
1372
1373 if (h->next == NULL || h->next->mx != h->mx) prev = h;
1374 }
1375
1376 return yield; /* No local hosts found: return HOST_FOUND or HOST_FIND_FAILED */
1377
1378 /* A host whose IP address matches a local IP address, or whose name matches
1379 something in hosts_treat_as_local has been found. */
1380
1381 FOUND_LOCAL:
1382
1383 if (prev == NULL)
1384 {
1385 HDEBUG(D_host_lookup) debug_printf((h->mx >= 0)?
1386 "local host has lowest MX\n" :
1387 "local host found for non-MX address\n");
1388 return HOST_FOUND_LOCAL;
1389 }
1390
1391 HDEBUG(D_host_lookup)
1392 {
1393 debug_printf("local host in host list - removed hosts:\n");
1394 for (h = prev->next; h != last->next; h = h->next)
1395 debug_printf(" %s %s %d\n", h->name, h->address, h->mx);
1396 }
1397
1398 if (removed != NULL) *removed = TRUE;
1399 prev->next = last->next;
1400 *lastptr = prev;
1401 return yield;
1402 }
1403
1404
1405
1406
1407 /*************************************************
1408 * Remove duplicate IPs in host list *
1409 *************************************************/
1410
1411 /* You would think that administrators could set up their DNS records so that
1412 one ended up with a list of unique IP addresses after looking up A or MX
1413 records, but apparently duplication is common. So we scan such lists and
1414 remove the later duplicates. Note that we may get lists in which some host
1415 addresses are not set.
1416
1417 Arguments:
1418 host pointer to the first host in the chain
1419 lastptr pointer to pointer to the last host in the chain (may be updated)
1420
1421 Returns: nothing
1422 */
1423
1424 static void
1425 host_remove_duplicates(host_item *host, host_item **lastptr)
1426 {
1427 while (host != *lastptr)
1428 {
1429 if (host->address != NULL)
1430 {
1431 host_item *h = host;
1432 while (h != *lastptr)
1433 {
1434 if (h->next->address != NULL &&
1435 Ustrcmp(h->next->address, host->address) == 0)
1436 {
1437 DEBUG(D_host_lookup) debug_printf("duplicate IP address %s (MX=%d) "
1438 "removed\n", host->address, h->next->mx);
1439 if (h->next == *lastptr) *lastptr = h;
1440 h->next = h->next->next;
1441 }
1442 else h = h->next;
1443 }
1444 }
1445 /* If the last item was removed, host may have become == *lastptr */
1446 if (host != *lastptr) host = host->next;
1447 }
1448 }
1449
1450
1451
1452
1453 /*************************************************
1454 * Find sender host name by gethostbyaddr() *
1455 *************************************************/
1456
1457 /* This used to be the only way it was done, but it turns out that not all
1458 systems give aliases for calls to gethostbyaddr() - or one of the modern
1459 equivalents like getipnodebyaddr(). Fortunately, multiple PTR records are rare,
1460 but they can still exist. This function is now used only when a DNS lookup of
1461 the IP address fails, in order to give access to /etc/hosts.
1462
1463 Arguments: none
1464 Returns: OK, DEFER, FAIL
1465 */
1466
1467 static int
1468 host_name_lookup_byaddr(void)
1469 {
1470 int len;
1471 uschar *s, *t;
1472 struct hostent *hosts;
1473 struct in_addr addr;
1474 unsigned long time_msec;
1475
1476 if (slow_lookup_log) time_msec = get_time_in_ms();
1477
1478 /* Lookup on IPv6 system */
1479
1480 #if HAVE_IPV6
1481 if (Ustrchr(sender_host_address, ':') != NULL)
1482 {
1483 struct in6_addr addr6;
1484 if (inet_pton(AF_INET6, CS sender_host_address, &addr6) != 1)
1485 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "unable to parse \"%s\" as an "
1486 "IPv6 address", sender_host_address);
1487 #if HAVE_GETIPNODEBYADDR
1488 hosts = getipnodebyaddr(CS &addr6, sizeof(addr6), AF_INET6, &h_errno);
1489 #else
1490 hosts = gethostbyaddr(CS &addr6, sizeof(addr6), AF_INET6);
1491 #endif
1492 }
1493 else
1494 {
1495 if (inet_pton(AF_INET, CS sender_host_address, &addr) != 1)
1496 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "unable to parse \"%s\" as an "
1497 "IPv4 address", sender_host_address);
1498 #if HAVE_GETIPNODEBYADDR
1499 hosts = getipnodebyaddr(CS &addr, sizeof(addr), AF_INET, &h_errno);
1500 #else
1501 hosts = gethostbyaddr(CS &addr, sizeof(addr), AF_INET);
1502 #endif
1503 }
1504
1505 /* Do lookup on IPv4 system */
1506
1507 #else
1508 addr.s_addr = (S_ADDR_TYPE)inet_addr(CS sender_host_address);
1509 hosts = gethostbyaddr(CS(&addr), sizeof(addr), AF_INET);
1510 #endif
1511
1512 if ( slow_lookup_log
1513 && (time_msec = get_time_in_ms() - time_msec) > slow_lookup_log
1514 )
1515 log_long_lookup(US"name", sender_host_address, time_msec);
1516
1517 /* Failed to look up the host. */
1518
1519 if (hosts == NULL)
1520 {
1521 HDEBUG(D_host_lookup) debug_printf("IP address lookup failed: h_errno=%d\n",
1522 h_errno);
1523 return (h_errno == TRY_AGAIN || h_errno == NO_RECOVERY) ? DEFER : FAIL;
1524 }
1525
1526 /* It seems there are some records in the DNS that yield an empty name. We
1527 treat this as non-existent. In some operating systems, this is returned as an
1528 empty string; in others as a single dot. */
1529
1530 if (hosts->h_name == NULL || hosts->h_name[0] == 0 || hosts->h_name[0] == '.')
1531 {
1532 HDEBUG(D_host_lookup) debug_printf("IP address lookup yielded an empty name: "
1533 "treated as non-existent host name\n");
1534 return FAIL;
1535 }
1536
1537 /* Copy and lowercase the name, which is in static storage in many systems.
1538 Put it in permanent memory. */
1539
1540 s = (uschar *)hosts->h_name;
1541 len = Ustrlen(s) + 1;
1542 t = sender_host_name = store_get_perm(len);
1543 while (*s != 0) *t++ = tolower(*s++);
1544 *t = 0;
1545
1546 /* If the host has aliases, build a copy of the alias list */
1547
1548 if (hosts->h_aliases != NULL)
1549 {
1550 int count = 1;
1551 uschar **aliases, **ptr;
1552 for (aliases = USS hosts->h_aliases; *aliases != NULL; aliases++) count++;
1553 ptr = sender_host_aliases = store_get_perm(count * sizeof(uschar *));
1554 for (aliases = USS hosts->h_aliases; *aliases != NULL; aliases++)
1555 {
1556 uschar *s = *aliases;
1557 int len = Ustrlen(s) + 1;
1558 uschar *t = *ptr++ = store_get_perm(len);
1559 while (*s != 0) *t++ = tolower(*s++);
1560 *t = 0;
1561 }
1562 *ptr = NULL;
1563 }
1564
1565 return OK;
1566 }
1567
1568
1569
1570 /*************************************************
1571 * Find host name for incoming call *
1572 *************************************************/
1573
1574 /* Put the name in permanent store, pointed to by sender_host_name. We also set
1575 up a list of alias names, pointed to by sender_host_alias. The list is
1576 NULL-terminated. The incoming address is in sender_host_address, either in
1577 dotted-quad form for IPv4 or in colon-separated form for IPv6.
1578
1579 This function does a thorough check that the names it finds point back to the
1580 incoming IP address. Any that do not are discarded. Note that this is relied on
1581 by the ACL reverse_host_lookup check.
1582
1583 On some systems, get{host,ipnode}byaddr() appears to do this internally, but
1584 this it not universally true. Also, for release 4.30, this function was changed
1585 to do a direct DNS lookup first, by default[1], because it turns out that that
1586 is the only guaranteed way to find all the aliases on some systems. My
1587 experiments indicate that Solaris gethostbyaddr() gives the aliases for but
1588 Linux does not.
1589
1590 [1] The actual order is controlled by the host_lookup_order option.
1591
1592 Arguments: none
1593 Returns: OK on success, the answer being placed in the global variable
1594 sender_host_name, with any aliases in a list hung off
1595 sender_host_aliases
1596 FAIL if no host name can be found
1597 DEFER if a temporary error was encountered
1598
1599 The variable host_lookup_msg is set to an empty string on sucess, or to a
1600 reason for the failure otherwise, in a form suitable for tagging onto an error
1601 message, and also host_lookup_failed is set TRUE if the lookup failed. If there
1602 was a defer, host_lookup_deferred is set TRUE.
1603
1604 Any dynamically constructed string for host_lookup_msg must be in permanent
1605 store, because it might be used for several incoming messages on the same SMTP
1606 connection. */
1607
1608 int
1609 host_name_lookup(void)
1610 {
1611 int old_pool, rc;
1612 int sep = 0;
1613 uschar *hname, *save_hostname;
1614 uschar **aliases;
1615 uschar buffer[256];
1616 uschar *ordername;
1617 const uschar *list = host_lookup_order;
1618 dns_record *rr;
1619 dns_answer dnsa;
1620 dns_scan dnss;
1621
1622 sender_host_dnssec = host_lookup_deferred = host_lookup_failed = FALSE;
1623
1624 HDEBUG(D_host_lookup)
1625 debug_printf("looking up host name for %s\n", sender_host_address);
1626
1627 /* For testing the case when a lookup does not complete, we have a special
1628 reserved IP address. */
1629
1630 if (running_in_test_harness &&
1631 Ustrcmp(sender_host_address, "99.99.99.99") == 0)
1632 {
1633 HDEBUG(D_host_lookup)
1634 debug_printf("Test harness: host name lookup returns DEFER\n");
1635 host_lookup_deferred = TRUE;
1636 return DEFER;
1637 }
1638
1639 /* Do lookups directly in the DNS or via gethostbyaddr() (or equivalent), in
1640 the order specified by the host_lookup_order option. */
1641
1642 while ((ordername = string_nextinlist(&list, &sep, buffer, sizeof(buffer))))
1643 {
1644 if (strcmpic(ordername, US"bydns") == 0)
1645 {
1646 dns_init(FALSE, FALSE, FALSE); /* dnssec ctrl by dns_dnssec_ok glbl */
1647 dns_build_reverse(sender_host_address, buffer);
1648 rc = dns_lookup_timerwrap(&dnsa, buffer, T_PTR, NULL);
1649
1650 /* The first record we come across is used for the name; others are
1651 considered to be aliases. We have to scan twice, in order to find out the
1652 number of aliases. However, if all the names are empty, we will behave as
1653 if failure. (PTR records that yield empty names have been encountered in
1654 the DNS.) */
1655
1656 if (rc == DNS_SUCCEED)
1657 {
1658 uschar **aptr = NULL;
1659 int ssize = 264;
1660 int count = 0;
1661 int old_pool = store_pool;
1662
1663 sender_host_dnssec = dns_is_secure(&dnsa);
1664 DEBUG(D_dns)
1665 debug_printf("Reverse DNS security status: %s\n",
1666 sender_host_dnssec ? "DNSSEC verified (AD)" : "unverified");
1667
1668 store_pool = POOL_PERM; /* Save names in permanent storage */
1669
1670 for (rr = dns_next_rr(&dnsa, &dnss, RESET_ANSWERS);
1671 rr != NULL;
1672 rr = dns_next_rr(&dnsa, &dnss, RESET_NEXT))
1673 {
1674 if (rr->type == T_PTR) count++;
1675 }
1676
1677 /* Get store for the list of aliases. For compatibility with
1678 gethostbyaddr, we make an empty list if there are none. */
1679
1680 aptr = sender_host_aliases = store_get(count * sizeof(uschar *));
1681
1682 /* Re-scan and extract the names */
1683
1684 for (rr = dns_next_rr(&dnsa, &dnss, RESET_ANSWERS);
1685 rr != NULL;
1686 rr = dns_next_rr(&dnsa, &dnss, RESET_NEXT))
1687 {
1688 uschar *s = NULL;
1689 if (rr->type != T_PTR) continue;
1690 s = store_get(ssize);
1691
1692 /* If an overlong response was received, the data will have been
1693 truncated and dn_expand may fail. */
1694
1695 if (dn_expand(dnsa.answer, dnsa.answer + dnsa.answerlen,
1696 (uschar *)(rr->data), (DN_EXPAND_ARG4_TYPE)(s), ssize) < 0)
1697 {
1698 log_write(0, LOG_MAIN, "host name alias list truncated for %s",
1699 sender_host_address);
1700 break;
1701 }
1702
1703 store_reset(s + Ustrlen(s) + 1);
1704 if (s[0] == 0)
1705 {
1706 HDEBUG(D_host_lookup) debug_printf("IP address lookup yielded an "
1707 "empty name: treated as non-existent host name\n");
1708 continue;
1709 }
1710 if (!sender_host_name) sender_host_name = s;
1711 else *aptr++ = s;
1712 while (*s != 0) { *s = tolower(*s); s++; }
1713 }
1714
1715 *aptr = NULL; /* End of alias list */
1716 store_pool = old_pool; /* Reset store pool */
1717
1718 /* If we've found a names, break out of the "order" loop */
1719
1720 if (sender_host_name != NULL) break;
1721 }
1722
1723 /* If the DNS lookup deferred, we must also defer. */
1724
1725 if (rc == DNS_AGAIN)
1726 {
1727 HDEBUG(D_host_lookup)
1728 debug_printf("IP address PTR lookup gave temporary error\n");
1729 host_lookup_deferred = TRUE;
1730 return DEFER;
1731 }
1732 }
1733
1734 /* Do a lookup using gethostbyaddr() - or equivalent */
1735
1736 else if (strcmpic(ordername, US"byaddr") == 0)
1737 {
1738 HDEBUG(D_host_lookup)
1739 debug_printf("IP address lookup using gethostbyaddr()\n");
1740 rc = host_name_lookup_byaddr();
1741 if (rc == DEFER)
1742 {
1743 host_lookup_deferred = TRUE;
1744 return rc; /* Can't carry on */
1745 }
1746 if (rc == OK) break; /* Found a name */
1747 }
1748 } /* Loop for bydns/byaddr scanning */
1749
1750 /* If we have failed to find a name, return FAIL and log when required.
1751 NB host_lookup_msg must be in permanent store. */
1752
1753 if (sender_host_name == NULL)
1754 {
1755 if (host_checking || !log_testing_mode)
1756 log_write(L_host_lookup_failed, LOG_MAIN, "no host name found for IP "
1757 "address %s", sender_host_address);
1758 host_lookup_msg = US" (failed to find host name from IP address)";
1759 host_lookup_failed = TRUE;
1760 return FAIL;
1761 }
1762
1763 HDEBUG(D_host_lookup)
1764 {
1765 uschar **aliases = sender_host_aliases;
1766 debug_printf("IP address lookup yielded \"%s\"\n", sender_host_name);
1767 while (*aliases != NULL) debug_printf(" alias \"%s\"\n", *aliases++);
1768 }
1769
1770 /* We need to verify that a forward lookup on the name we found does indeed
1771 correspond to the address. This is for security: in principle a malefactor who
1772 happened to own a reverse zone could set it to point to any names at all.
1773
1774 This code was present in versions of Exim before 3.20. At that point I took it
1775 out because I thought that gethostbyaddr() did the check anyway. It turns out
1776 that this isn't always the case, so it's coming back in at 4.01. This version
1777 is actually better, because it also checks aliases.
1778
1779 The code was made more robust at release 4.21. Prior to that, it accepted all
1780 the names if any of them had the correct IP address. Now the code checks all
1781 the names, and accepts only those that have the correct IP address. */
1782
1783 save_hostname = sender_host_name; /* Save for error messages */
1784 aliases = sender_host_aliases;
1785 for (hname = sender_host_name; hname != NULL; hname = *aliases++)
1786 {
1787 int rc;
1788 BOOL ok = FALSE;
1789 host_item h;
1790 dnssec_domains d;
1791
1792 h.next = NULL;
1793 h.name = hname;
1794 h.mx = MX_NONE;
1795 h.address = NULL;
1796 d.request = sender_host_dnssec ? US"*" : NULL;;
1797 d.require = NULL;
1798
1799 if ( (rc = host_find_bydns(&h, NULL, HOST_FIND_BY_A,
1800 NULL, NULL, NULL, &d, NULL, NULL)) == HOST_FOUND
1801 || rc == HOST_FOUND_LOCAL
1802 )
1803 {
1804 host_item *hh;
1805 HDEBUG(D_host_lookup) debug_printf("checking addresses for %s\n", hname);
1806
1807 /* If the forward lookup was not secure we cancel the is-secure variable */
1808
1809 DEBUG(D_dns) debug_printf("Forward DNS security status: %s\n",
1810 h.dnssec == DS_YES ? "DNSSEC verified (AD)" : "unverified");
1811 if (h.dnssec != DS_YES) sender_host_dnssec = FALSE;
1812
1813 for (hh = &h; hh != NULL; hh = hh->next)
1814 if (host_is_in_net(hh->address, sender_host_address, 0))
1815 {
1816 HDEBUG(D_host_lookup) debug_printf(" %s OK\n", hh->address);
1817 ok = TRUE;
1818 break;
1819 }
1820 else
1821 HDEBUG(D_host_lookup) debug_printf(" %s\n", hh->address);
1822
1823 if (!ok) HDEBUG(D_host_lookup)
1824 debug_printf("no IP address for %s matched %s\n", hname,
1825 sender_host_address);
1826 }
1827 else if (rc == HOST_FIND_AGAIN)
1828 {
1829 HDEBUG(D_host_lookup) debug_printf("temporary error for host name lookup\n");
1830 host_lookup_deferred = TRUE;
1831 sender_host_name = NULL;
1832 return DEFER;
1833 }
1834 else
1835 HDEBUG(D_host_lookup) debug_printf("no IP addresses found for %s\n", hname);
1836
1837 /* If this name is no good, and it's the sender name, set it null pro tem;
1838 if it's an alias, just remove it from the list. */
1839
1840 if (!ok)
1841 {
1842 if (hname == sender_host_name) sender_host_name = NULL; else
1843 {
1844 uschar **a; /* Don't amalgamate - some */
1845 a = --aliases; /* compilers grumble */
1846 while (*a != NULL) { *a = a[1]; a++; }
1847 }
1848 }
1849 }
1850
1851 /* If sender_host_name == NULL, it means we didn't like the name. Replace
1852 it with the first alias, if there is one. */
1853
1854 if (sender_host_name == NULL && *sender_host_aliases != NULL)
1855 sender_host_name = *sender_host_aliases++;
1856
1857 /* If we now have a main name, all is well. */
1858
1859 if (sender_host_name != NULL) return OK;
1860
1861 /* We have failed to find an address that matches. */
1862
1863 HDEBUG(D_host_lookup)
1864 debug_printf("%s does not match any IP address for %s\n",
1865 sender_host_address, save_hostname);
1866
1867 /* This message must be in permanent store */
1868
1869 old_pool = store_pool;
1870 store_pool = POOL_PERM;
1871 host_lookup_msg = string_sprintf(" (%s does not match any IP address for %s)",
1872 sender_host_address, save_hostname);
1873 store_pool = old_pool;
1874 host_lookup_failed = TRUE;
1875 return FAIL;
1876 }
1877
1878
1879
1880
1881 /*************************************************
1882 * Find IP address(es) for host by name *
1883 *************************************************/
1884
1885 /* The input is a host_item structure with the name filled in and the address
1886 field set to NULL. We use gethostbyname() or getipnodebyname() or
1887 gethostbyname2(), as appropriate. Of course, these functions may use the DNS,
1888 but they do not do MX processing. It appears, however, that in some systems the
1889 current setting of resolver options is used when one of these functions calls
1890 the resolver. For this reason, we call dns_init() at the start, with arguments
1891 influenced by bits in "flags", just as we do for host_find_bydns().
1892
1893 The second argument provides a host list (usually an IP list) of hosts to
1894 ignore. This makes it possible to ignore IPv6 link-local addresses or loopback
1895 addresses in unreasonable places.
1896
1897 The lookup may result in a change of name. For compatibility with the dns
1898 lookup, return this via fully_qualified_name as well as updating the host item.
1899 The lookup may also yield more than one IP address, in which case chain on
1900 subsequent host_item structures.
1901
1902 Arguments:
1903 host a host item with the name and MX filled in;
1904 the address is to be filled in;
1905 multiple IP addresses cause other host items to be
1906 chained on.
1907 ignore_target_hosts a list of hosts to ignore
1908 flags HOST_FIND_QUALIFY_SINGLE ) passed to
1909 HOST_FIND_SEARCH_PARENTS ) dns_init()
1910 fully_qualified_name if not NULL, set to point to host name for
1911 compatibility with host_find_bydns
1912 local_host_check TRUE if a check for the local host is wanted
1913
1914 Returns: HOST_FIND_FAILED Failed to find the host or domain
1915 HOST_FIND_AGAIN Try again later
1916 HOST_FOUND Host found - data filled in
1917 HOST_FOUND_LOCAL Host found and is the local host
1918 */
1919
1920 int
1921 host_find_byname(host_item *host, const uschar *ignore_target_hosts, int flags,
1922 const uschar **fully_qualified_name, BOOL local_host_check)
1923 {
1924 int i, yield, times;
1925 uschar **addrlist;
1926 host_item *last = NULL;
1927 BOOL temp_error = FALSE;
1928 #if HAVE_IPV6
1929 int af;
1930 #endif
1931
1932 /* If we are in the test harness, a name ending in .test.again.dns always
1933 forces a temporary error response, unless the name is in
1934 dns_again_means_nonexist. */
1935
1936 if (running_in_test_harness)
1937 {
1938 const uschar *endname = host->name + Ustrlen(host->name);
1939 if (Ustrcmp(endname - 14, "test.again.dns") == 0) goto RETURN_AGAIN;
1940 }
1941
1942 /* Make sure DNS options are set as required. This appears to be necessary in
1943 some circumstances when the get..byname() function actually calls the DNS. */
1944
1945 dns_init((flags & HOST_FIND_QUALIFY_SINGLE) != 0,
1946 (flags & HOST_FIND_SEARCH_PARENTS) != 0,
1947 FALSE); /* Cannot retrieve dnssec status so do not request */
1948
1949 /* In an IPv6 world, unless IPv6 has been disabled, we need to scan for both
1950 kinds of address, so go round the loop twice. Note that we have ensured that
1951 AF_INET6 is defined even in an IPv4 world, which makes for slightly tidier
1952 code. However, if dns_ipv4_lookup matches the domain, we also just do IPv4
1953 lookups here (except when testing standalone). */
1954
1955 #if HAVE_IPV6
1956 #ifdef STAND_ALONE
1957 if (disable_ipv6)
1958 #else
1959 if (disable_ipv6 ||
1960 (dns_ipv4_lookup != NULL &&
1961 match_isinlist(host->name, CUSS &dns_ipv4_lookup, 0, NULL, NULL,
1962 MCL_DOMAIN, TRUE, NULL) == OK))
1963 #endif
1964
1965 { af = AF_INET; times = 1; }
1966 else
1967 { af = AF_INET6; times = 2; }
1968
1969 /* No IPv6 support */
1970
1971 #else /* HAVE_IPV6 */
1972 times = 1;
1973 #endif /* HAVE_IPV6 */
1974
1975 /* Initialize the flag that gets set for DNS syntax check errors, so that the
1976 interface to this function can be similar to host_find_bydns. */
1977
1978 host_find_failed_syntax = FALSE;
1979
1980 /* Loop to look up both kinds of address in an IPv6 world */
1981
1982 for (i = 1; i <= times;
1983 #if HAVE_IPV6
1984 af = AF_INET, /* If 2 passes, IPv4 on the second */
1985 #endif
1986 i++)
1987 {
1988 BOOL ipv4_addr;
1989 int error_num = 0;
1990 struct hostent *hostdata;
1991 unsigned long time_msec;
1992
1993 #ifdef STAND_ALONE
1994 printf("Looking up: %s\n", host->name);
1995 #endif
1996
1997 if (slow_lookup_log) time_msec = get_time_in_ms();
1998
1999 #if HAVE_IPV6
2000 if (running_in_test_harness)
2001 hostdata = host_fake_gethostbyname(host->name, af, &error_num);
2002 else
2003 {
2004 #if HAVE_GETIPNODEBYNAME
2005 hostdata = getipnodebyname(CS host->name, af, 0, &error_num);
2006 #else
2007 hostdata = gethostbyname2(CS host->name, af);
2008 error_num = h_errno;
2009 #endif
2010 }
2011
2012 #else /* not HAVE_IPV6 */
2013 if (running_in_test_harness)
2014 hostdata = host_fake_gethostbyname(host->name, AF_INET, &error_num);
2015 else
2016 {
2017 hostdata = gethostbyname(CS host->name);
2018 error_num = h_errno;
2019 }
2020 #endif /* HAVE_IPV6 */
2021
2022 if (slow_lookup_log
2023 && (time_msec = get_time_in_ms() - time_msec) > slow_lookup_log)
2024 log_long_lookup(US"name", host->name, time_msec);
2025
2026 if (hostdata == NULL)
2027 {
2028 uschar *error;
2029 switch (error_num)
2030 {
2031 case HOST_NOT_FOUND: error = US"HOST_NOT_FOUND"; break;
2032 case TRY_AGAIN: error = US"TRY_AGAIN"; break;
2033 case NO_RECOVERY: error = US"NO_RECOVERY"; break;
2034 case NO_DATA: error = US"NO_DATA"; break;
2035 #if NO_DATA != NO_ADDRESS
2036 case NO_ADDRESS: error = US"NO_ADDRESS"; break;
2037 #endif
2038 default: error = US"?"; break;
2039 }
2040
2041 DEBUG(D_host_lookup) debug_printf("%s returned %d (%s)\n",
2042 #if HAVE_IPV6
2043 #if HAVE_GETIPNODEBYNAME
2044 (af == AF_INET6)? "getipnodebyname(af=inet6)" : "getipnodebyname(af=inet)",
2045 #else
2046 (af == AF_INET6)? "gethostbyname2(af=inet6)" : "gethostbyname2(af=inet)",
2047 #endif
2048 #else
2049 "gethostbyname",
2050 #endif
2051 error_num, error);
2052
2053 if (error_num == TRY_AGAIN || error_num == NO_RECOVERY) temp_error = TRUE;
2054 continue;
2055 }
2056 if ((hostdata->h_addr_list)[0] == NULL) continue;
2057
2058 /* Replace the name with the fully qualified one if necessary, and fill in
2059 the fully_qualified_name pointer. */
2060
2061 if (hostdata->h_name[0] != 0 &&
2062 Ustrcmp(host->name, hostdata->h_name) != 0)
2063 host->name = string_copy_dnsdomain((uschar *)hostdata->h_name);
2064 if (fully_qualified_name != NULL) *fully_qualified_name = host->name;
2065
2066 /* Get the list of addresses. IPv4 and IPv6 addresses can be distinguished
2067 by their different lengths. Scan the list, ignoring any that are to be
2068 ignored, and build a chain from the rest. */
2069
2070 ipv4_addr = hostdata->h_length == sizeof(struct in_addr);
2071
2072 for (addrlist = USS hostdata->h_addr_list; *addrlist != NULL; addrlist++)
2073 {
2074 uschar *text_address =
2075 host_ntoa(ipv4_addr? AF_INET:AF_INET6, *addrlist, NULL, NULL);
2076
2077 #ifndef STAND_ALONE
2078 if (ignore_target_hosts != NULL &&
2079 verify_check_this_host(&ignore_target_hosts, NULL, host->name,
2080 text_address, NULL) == OK)
2081 {
2082 DEBUG(D_host_lookup)
2083 debug_printf("ignored host %s [%s]\n", host->name, text_address);
2084 continue;
2085 }
2086 #endif
2087
2088 /* If this is the first address, last == NULL and we put the data in the
2089 original block. */
2090
2091 if (last == NULL)
2092 {
2093 host->address = text_address;
2094 host->port = PORT_NONE;
2095 host->status = hstatus_unknown;
2096 host->why = hwhy_unknown;
2097 host->dnssec = DS_UNK;
2098 last = host;
2099 }
2100
2101 /* Else add further host item blocks for any other addresses, keeping
2102 the order. */
2103
2104 else
2105 {
2106 host_item *next = store_get(sizeof(host_item));
2107 next->name = host->name;
2108 next->mx = host->mx;
2109 next->address = text_address;
2110 next->port = PORT_NONE;
2111 next->status = hstatus_unknown;
2112 next->why = hwhy_unknown;
2113 next->dnssec = DS_UNK;
2114 next->last_try = 0;
2115 next->next = last->next;
2116 last->next = next;
2117 last = next;
2118 }
2119 }
2120 }
2121
2122 /* If no hosts were found, the address field in the original host block will be
2123 NULL. If temp_error is set, at least one of the lookups gave a temporary error,
2124 so we pass that back. */
2125
2126 if (host->address == NULL)
2127 {
2128 uschar *msg =
2129 #ifndef STAND_ALONE
2130 (message_id[0] == 0 && smtp_in != NULL)?
2131 string_sprintf("no IP address found for host %s (during %s)", host->name,
2132 smtp_get_connection_info()) :
2133 #endif
2134 string_sprintf("no IP address found for host %s", host->name);
2135
2136 HDEBUG(D_host_lookup) debug_printf("%s\n", msg);
2137 if (temp_error) goto RETURN_AGAIN;
2138 if (host_checking || !log_testing_mode)
2139 log_write(L_host_lookup_failed, LOG_MAIN, "%s", msg);
2140 return HOST_FIND_FAILED;
2141 }
2142
2143 /* Remove any duplicate IP addresses, then check to see if this is the local
2144 host if required. */
2145
2146 host_remove_duplicates(host, &last);
2147 yield = local_host_check?
2148 host_scan_for_local_hosts(host, &last, NULL) : HOST_FOUND;
2149
2150 HDEBUG(D_host_lookup)
2151 {
2152 const host_item *h;
2153 if (fully_qualified_name != NULL)
2154 debug_printf("fully qualified name = %s\n", *fully_qualified_name);
2155 debug_printf("%s looked up these IP addresses:\n",
2156 #if HAVE_IPV6
2157 #if HAVE_GETIPNODEBYNAME
2158 "getipnodebyname"
2159 #else
2160 "gethostbyname2"
2161 #endif
2162 #else
2163 "gethostbyname"
2164 #endif
2165 );
2166 for (h = host; h != last->next; h = h->next)
2167 debug_printf(" name=%s address=%s\n", h->name,
2168 (h->address == NULL)? US"<null>" : h->address);
2169 }
2170
2171 /* Return the found status. */
2172
2173 return yield;
2174
2175 /* Handle the case when there is a temporary error. If the name matches
2176 dns_again_means_nonexist, return permanent rather than temporary failure. */
2177
2178 RETURN_AGAIN:
2179 {
2180 #ifndef STAND_ALONE
2181 int rc;
2182 const uschar *save = deliver_domain;
2183 deliver_domain = host->name; /* set $domain */
2184 rc = match_isinlist(host->name, CUSS &dns_again_means_nonexist, 0, NULL, NULL,
2185 MCL_DOMAIN, TRUE, NULL);
2186 deliver_domain = save;
2187 if (rc == OK)
2188 {
2189 DEBUG(D_host_lookup) debug_printf("%s is in dns_again_means_nonexist: "
2190 "returning HOST_FIND_FAILED\n", host->name);
2191 return HOST_FIND_FAILED;
2192 }
2193 #endif
2194 return HOST_FIND_AGAIN;
2195 }
2196 }
2197
2198
2199
2200 /*************************************************
2201 * Fill in a host address from the DNS *
2202 *************************************************/
2203
2204 /* Given a host item, with its name, port and mx fields set, and its address
2205 field set to NULL, fill in its IP address from the DNS. If it is multi-homed,
2206 create additional host items for the additional addresses, copying all the
2207 other fields, and randomizing the order.
2208
2209 On IPv6 systems, A6 records are sought first (but only if support for A6 is
2210 configured - they may never become mainstream), then AAAA records are sought,
2211 and finally A records are sought as well.
2212
2213 The host name may be changed if the DNS returns a different name - e.g. fully
2214 qualified or changed via CNAME. If fully_qualified_name is not NULL, dns_lookup
2215 ensures that it points to the fully qualified name. However, this is the fully
2216 qualified version of the original name; if a CNAME is involved, the actual
2217 canonical host name may be different again, and so we get it directly from the
2218 relevant RR. Note that we do NOT change the mx field of the host item in this
2219 function as it may be called to set the addresses of hosts taken from MX
2220 records.
2221
2222 Arguments:
2223 host points to the host item we're filling in
2224 lastptr points to pointer to last host item in a chain of
2225 host items (may be updated if host is last and gets
2226 extended because multihomed)
2227 ignore_target_hosts list of hosts to ignore
2228 allow_ip if TRUE, recognize an IP address and return it
2229 fully_qualified_name if not NULL, return fully qualified name here if
2230 the contents are different (i.e. it must be preset
2231 to something)
2232 dnnssec_require if TRUE check the DNS result AD bit
2233
2234 Returns: HOST_FIND_FAILED couldn't find A record
2235 HOST_FIND_AGAIN try again later
2236 HOST_FOUND found AAAA and/or A record(s)
2237 HOST_IGNORED found, but all IPs ignored
2238 */
2239
2240 static int
2241 set_address_from_dns(host_item *host, host_item **lastptr,
2242 const uschar *ignore_target_hosts, BOOL allow_ip,
2243 const uschar **fully_qualified_name,
2244 BOOL dnssec_request, BOOL dnssec_require)
2245 {
2246 dns_record *rr;
2247 host_item *thishostlast = NULL; /* Indicates not yet filled in anything */
2248 BOOL v6_find_again = FALSE;
2249 int i;
2250
2251 /* If allow_ip is set, a name which is an IP address returns that value
2252 as its address. This is used for MX records when allow_mx_to_ip is set, for
2253 those sites that feel they have to flaunt the RFC rules. */
2254
2255 if (allow_ip && string_is_ip_address(host->name, NULL) != 0)
2256 {
2257 #ifndef STAND_ALONE
2258 if (ignore_target_hosts != NULL &&
2259 verify_check_this_host(&ignore_target_hosts, NULL, host->name,
2260 host->name, NULL) == OK)
2261 return HOST_IGNORED;
2262 #endif
2263
2264 host->address = host->name;
2265 return HOST_FOUND;
2266 }
2267
2268 /* On an IPv6 system, unless IPv6 is disabled, go round the loop up to three
2269 times, looking for A6 and AAAA records the first two times. However, unless
2270 doing standalone testing, we force an IPv4 lookup if the domain matches
2271 dns_ipv4_lookup is set. Since A6 records look like being abandoned, support
2272 them only if explicitly configured to do so. On an IPv4 system, go round the
2273 loop once only, looking only for A records. */
2274
2275 #if HAVE_IPV6
2276 #ifndef STAND_ALONE
2277 if (disable_ipv6 || (dns_ipv4_lookup != NULL &&
2278 match_isinlist(host->name, CUSS &dns_ipv4_lookup, 0, NULL, NULL,
2279 MCL_DOMAIN, TRUE, NULL) == OK))
2280 i = 0; /* look up A records only */
2281 else
2282 #endif /* STAND_ALONE */
2283
2284 i = 1; /* look up AAAA and A records */
2285
2286 /* The IPv4 world */
2287
2288 #else /* HAVE_IPV6 */
2289 i = 0; /* look up A records only */
2290 #endif /* HAVE_IPV6 */
2291
2292 for (; i >= 0; i--)
2293 {
2294 static int types[] = { T_A, T_AAAA, T_A6 };
2295 int type = types[i];
2296 int randoffset = (i == 0)? 500 : 0; /* Ensures v6 sorts before v4 */
2297 dns_answer dnsa;
2298 dns_scan dnss;
2299
2300 int rc = dns_lookup_timerwrap(&dnsa, host->name, type, fully_qualified_name);
2301 lookup_dnssec_authenticated = !dnssec_request ? NULL
2302 : dns_is_secure(&dnsa) ? US"yes" : US"no";
2303
2304 /* We want to return HOST_FIND_AGAIN if one of the A, A6, or AAAA lookups
2305 fails or times out, but not if another one succeeds. (In the early
2306 IPv6 days there are name servers that always fail on AAAA, but are happy
2307 to give out an A record. We want to proceed with that A record.) */
2308
2309 if (rc != DNS_SUCCEED)
2310 {
2311 if (i == 0) /* Just tried for an A record, i.e. end of loop */
2312 {
2313 if (host->address != NULL) return HOST_FOUND; /* A6 or AAAA was found */
2314 if (rc == DNS_AGAIN || rc == DNS_FAIL || v6_find_again)
2315 return HOST_FIND_AGAIN;
2316 return HOST_FIND_FAILED; /* DNS_NOMATCH or DNS_NODATA */
2317 }
2318
2319 /* Tried for an A6 or AAAA record: remember if this was a temporary
2320 error, and look for the next record type. */
2321
2322 if (rc != DNS_NOMATCH && rc != DNS_NODATA) v6_find_again = TRUE;
2323 continue;
2324 }
2325
2326 if (dnssec_request)
2327 {
2328 if (dns_is_secure(&dnsa))
2329 {
2330 DEBUG(D_host_lookup) debug_printf("%s A DNSSEC\n", host->name);
2331 if (host->dnssec == DS_UNK) /* set in host_find_bydns() */
2332 host->dnssec = DS_YES;
2333 }
2334 else
2335 {
2336 if (dnssec_require)
2337 {
2338 log_write(L_host_lookup_failed, LOG_MAIN,
2339 "dnssec fail on %s for %.256s",
2340 i>1 ? "A6" : i>0 ? "AAAA" : "A", host->name);
2341 continue;
2342 }
2343 if (host->dnssec == DS_YES) /* set in host_find_bydns() */
2344 {
2345 DEBUG(D_host_lookup) debug_printf("%s A cancel DNSSEC\n", host->name);
2346 host->dnssec = DS_NO;
2347 lookup_dnssec_authenticated = US"no";
2348 }
2349 }
2350 }
2351
2352 /* Lookup succeeded: fill in the given host item with the first non-ignored
2353 address found; create additional items for any others. A single A6 record
2354 may generate more than one address. The lookup had a chance to update the
2355 fqdn; we do not want any later times round the loop to do so. */
2356
2357 fully_qualified_name = NULL;
2358
2359 for (rr = dns_next_rr(&dnsa, &dnss, RESET_ANSWERS);
2360 rr;
2361 rr = dns_next_rr(&dnsa, &dnss, RESET_NEXT))
2362 {
2363 if (rr->type == type)
2364 {
2365 /* dns_address *da = dns_address_from_rr(&dnsa, rr); */
2366
2367 dns_address *da;
2368 da = dns_address_from_rr(&dnsa, rr);
2369
2370 DEBUG(D_host_lookup)
2371 {
2372 if (!da) debug_printf("no addresses extracted from A6 RR for %s\n",
2373 host->name);
2374 }
2375
2376 /* This loop runs only once for A and AAAA records, but may run
2377 several times for an A6 record that generated multiple addresses. */
2378
2379 for (; da; da = da->next)
2380 {
2381 #ifndef STAND_ALONE
2382 if (ignore_target_hosts != NULL &&
2383 verify_check_this_host(&ignore_target_hosts, NULL,
2384 host->name, da->address, NULL) == OK)
2385 {
2386 DEBUG(D_host_lookup)
2387 debug_printf("ignored host %s [%s]\n", host->name, da->address);
2388 continue;
2389 }
2390 #endif
2391
2392 /* If this is the first address, stick it in the given host block,
2393 and change the name if the returned RR has a different name. */
2394
2395 if (thishostlast == NULL)
2396 {
2397 if (strcmpic(host->name, rr->name) != 0)
2398 host->name = string_copy_dnsdomain(rr->name);
2399 host->address = da->address;
2400 host->sort_key = host->mx * 1000 + random_number(500) + randoffset;
2401 host->status = hstatus_unknown;
2402 host->why = hwhy_unknown;
2403 thishostlast = host;
2404 }
2405
2406 /* Not the first address. Check for, and ignore, duplicates. Then
2407 insert in the chain at a random point. */
2408
2409 else
2410 {
2411 int new_sort_key;
2412 host_item *next;
2413
2414 /* End of our local chain is specified by "thishostlast". */
2415
2416 for (next = host;; next = next->next)
2417 {
2418 if (Ustrcmp(CS da->address, next->address) == 0) break;
2419 if (next == thishostlast) { next = NULL; break; }
2420 }
2421 if (next != NULL) continue; /* With loop for next address */
2422
2423 /* Not a duplicate */
2424
2425 new_sort_key = host->mx * 1000 + random_number(500) + randoffset;
2426 next = store_get(sizeof(host_item));
2427
2428 /* New address goes first: insert the new block after the first one
2429 (so as not to disturb the original pointer) but put the new address
2430 in the original block. */
2431
2432 if (new_sort_key < host->sort_key)
2433 {
2434 *next = *host; /* Copies port */
2435 host->next = next;
2436 host->address = da->address;
2437 host->sort_key = new_sort_key;
2438 if (thishostlast == host) thishostlast = next; /* Local last */
2439 if (*lastptr == host) *lastptr = next; /* Global last */
2440 }
2441
2442 /* Otherwise scan down the addresses for this host to find the
2443 one to insert after. */
2444
2445 else
2446 {
2447 host_item *h = host;
2448 while (h != thishostlast)
2449 {
2450 if (new_sort_key < h->next->sort_key) break;
2451 h = h->next;
2452 }
2453 *next = *h; /* Copies port */
2454 h->next = next;
2455 next->address = da->address;
2456 next->sort_key = new_sort_key;
2457 if (h == thishostlast) thishostlast = next; /* Local last */
2458 if (h == *lastptr) *lastptr = next; /* Global last */
2459 }
2460 }
2461 }
2462 }
2463 }
2464 }
2465
2466 /* Control gets here only if the third lookup (the A record) succeeded.
2467 However, the address may not be filled in if it was ignored. */
2468
2469 return (host->address == NULL)? HOST_IGNORED : HOST_FOUND;
2470 }
2471
2472
2473
2474
2475 /*************************************************
2476 * Find IP addresses and host names via DNS *
2477 *************************************************/
2478
2479 /* The input is a host_item structure with the name field filled in and the
2480 address field set to NULL. This may be in a chain of other host items. The
2481 lookup may result in more than one IP address, in which case we must created
2482 new host blocks for the additional addresses, and insert them into the chain.
2483 The original name may not be fully qualified. Use the fully_qualified_name
2484 argument to return the official name, as returned by the resolver.
2485
2486 Arguments:
2487 host point to initial host item
2488 ignore_target_hosts a list of hosts to ignore
2489 whichrrs flags indicating which RRs to look for:
2490 HOST_FIND_BY_SRV => look for SRV
2491 HOST_FIND_BY_MX => look for MX
2492 HOST_FIND_BY_A => look for A or AAAA
2493 also flags indicating how the lookup is done
2494 HOST_FIND_QUALIFY_SINGLE ) passed to the
2495 HOST_FIND_SEARCH_PARENTS ) resolver
2496 srv_service when SRV used, the service name
2497 srv_fail_domains DNS errors for these domains => assume nonexist
2498 mx_fail_domains DNS errors for these domains => assume nonexist
2499 dnssec_d.request => make dnssec request: domainlist
2500 dnssec_d.require => ditto and nonexist failures
2501 fully_qualified_name if not NULL, return fully-qualified name
2502 removed set TRUE if local host was removed from the list
2503
2504 Returns: HOST_FIND_FAILED Failed to find the host or domain;
2505 if there was a syntax error,
2506 host_find_failed_syntax is set.
2507 HOST_FIND_AGAIN Could not resolve at this time
2508 HOST_FOUND Host found
2509 HOST_FOUND_LOCAL The lowest MX record points to this
2510 machine, if MX records were found, or
2511 an A record that was found contains
2512 an address of the local host
2513 */
2514
2515 int
2516 host_find_bydns(host_item *host, const uschar *ignore_target_hosts, int whichrrs,
2517 uschar *srv_service, uschar *srv_fail_domains, uschar *mx_fail_domains,
2518 const dnssec_domains *dnssec_d,
2519 const uschar **fully_qualified_name, BOOL *removed)
2520 {
2521 host_item *h, *last;
2522 dns_record *rr;
2523 int rc = DNS_FAIL;
2524 int ind_type = 0;
2525 int yield;
2526 dns_answer dnsa;
2527 dns_scan dnss;
2528 BOOL dnssec_require = dnssec_d
2529 && match_isinlist(host->name, CUSS &dnssec_d->require,
2530 0, NULL, NULL, MCL_DOMAIN, TRUE, NULL) == OK;
2531 BOOL dnssec_request = dnssec_require
2532 || ( dnssec_d
2533 && match_isinlist(host->name, CUSS &dnssec_d->request,
2534 0, NULL, NULL, MCL_DOMAIN, TRUE, NULL) == OK);
2535 dnssec_status_t dnssec;
2536
2537 /* Set the default fully qualified name to the incoming name, initialize the
2538 resolver if necessary, set up the relevant options, and initialize the flag
2539 that gets set for DNS syntax check errors. */
2540
2541 if (fully_qualified_name != NULL) *fully_qualified_name = host->name;
2542 dns_init((whichrrs & HOST_FIND_QUALIFY_SINGLE) != 0,
2543 (whichrrs & HOST_FIND_SEARCH_PARENTS) != 0,
2544 dnssec_request);
2545 host_find_failed_syntax = FALSE;
2546
2547 /* First, if requested, look for SRV records. The service name is given; we
2548 assume TCP progocol. DNS domain names are constrained to a maximum of 256
2549 characters, so the code below should be safe. */
2550
2551 if ((whichrrs & HOST_FIND_BY_SRV) != 0)
2552 {
2553 uschar buffer[300];
2554 uschar *temp_fully_qualified_name = buffer;
2555 int prefix_length;
2556
2557 (void)sprintf(CS buffer, "_%s._tcp.%n%.256s", srv_service, &prefix_length,
2558 host->name);
2559 ind_type = T_SRV;
2560
2561 /* Search for SRV records. If the fully qualified name is different to
2562 the input name, pass back the new original domain, without the prepended
2563 magic. */
2564
2565 dnssec = DS_UNK;
2566 lookup_dnssec_authenticated = NULL;
2567 rc = dns_lookup_timerwrap(&dnsa, buffer, ind_type, CUSS &temp_fully_qualified_name);
2568
2569 if (dnssec_request)
2570 {
2571 if (dns_is_secure(&dnsa))
2572 { dnssec = DS_YES; lookup_dnssec_authenticated = US"yes"; }
2573 else
2574 { dnssec = DS_NO; lookup_dnssec_authenticated = US"no"; }
2575 }
2576
2577 if (temp_fully_qualified_name != buffer && fully_qualified_name != NULL)
2578 *fully_qualified_name = temp_fully_qualified_name + prefix_length;
2579
2580 /* On DNS failures, we give the "try again" error unless the domain is
2581 listed as one for which we continue. */
2582
2583 if (rc == DNS_SUCCEED && dnssec_require && !dns_is_secure(&dnsa))
2584 {
2585 log_write(L_host_lookup_failed, LOG_MAIN,
2586 "dnssec fail on SRV for %.256s", host->name);
2587 rc = DNS_FAIL;
2588 }
2589 if (rc == DNS_FAIL || rc == DNS_AGAIN)
2590 {
2591 #ifndef STAND_ALONE
2592 if (match_isinlist(host->name, CUSS &srv_fail_domains, 0, NULL, NULL,
2593 MCL_DOMAIN, TRUE, NULL) != OK)
2594 #endif
2595 { yield = HOST_FIND_AGAIN; goto out; }
2596 DEBUG(D_host_lookup) debug_printf("DNS_%s treated as DNS_NODATA "
2597 "(domain in srv_fail_domains)\n", (rc == DNS_FAIL)? "FAIL":"AGAIN");
2598 }
2599 }
2600
2601 /* If we did not find any SRV records, search the DNS for MX records, if
2602 requested to do so. If the result is DNS_NOMATCH, it means there is no such
2603 domain, and there's no point in going on to look for address records with the
2604 same domain. The result will be DNS_NODATA if the domain exists but has no MX
2605 records. On DNS failures, we give the "try again" error unless the domain is
2606 listed as one for which we continue. */
2607
2608 if (rc != DNS_SUCCEED && (whichrrs & HOST_FIND_BY_MX) != 0)
2609 {
2610 ind_type = T_MX;
2611 dnssec = DS_UNK;
2612 lookup_dnssec_authenticated = NULL;
2613 rc = dns_lookup_timerwrap(&dnsa, host->name, ind_type, fully_qualified_name);
2614
2615 if (dnssec_request)
2616 {
2617 if (dns_is_secure(&dnsa))
2618 {
2619 DEBUG(D_host_lookup) debug_printf("%s MX DNSSEC\n", host->name);
2620 dnssec = DS_YES; lookup_dnssec_authenticated = US"yes";
2621 }
2622 else
2623 {
2624 dnssec = DS_NO; lookup_dnssec_authenticated = US"no";
2625 }
2626 }
2627
2628 switch (rc)
2629 {
2630 case DNS_NOMATCH:
2631 yield = HOST_FIND_FAILED; goto out;
2632
2633 case DNS_SUCCEED:
2634 if (!dnssec_require || dns_is_secure(&dnsa))
2635 break;
2636 log_write(L_host_lookup_failed, LOG_MAIN,
2637 "dnssec fail on MX for %.256s", host->name);
2638 rc = DNS_FAIL;
2639 /*FALLTHROUGH*/
2640
2641 case DNS_FAIL:
2642 case DNS_AGAIN:
2643 #ifndef STAND_ALONE
2644 if (match_isinlist(host->name, CUSS &mx_fail_domains, 0, NULL, NULL,
2645 MCL_DOMAIN, TRUE, NULL) != OK)
2646 #endif
2647 { yield = HOST_FIND_AGAIN; goto out; }
2648 DEBUG(D_host_lookup) debug_printf("DNS_%s treated as DNS_NODATA "
2649 "(domain in mx_fail_domains)\n", (rc == DNS_FAIL)? "FAIL":"AGAIN");
2650 break;
2651 }
2652 }
2653
2654 /* If we haven't found anything yet, and we are requested to do so, try for an
2655 A or AAAA record. If we find it (or them) check to see that it isn't the local
2656 host. */
2657
2658 if (rc != DNS_SUCCEED)
2659 {
2660 if ((whichrrs & HOST_FIND_BY_A) == 0)
2661 {
2662 DEBUG(D_host_lookup) debug_printf("Address records are not being sought\n");
2663 yield = HOST_FIND_FAILED;
2664 goto out;
2665 }
2666
2667 last = host; /* End of local chainlet */
2668 host->mx = MX_NONE;
2669 host->port = PORT_NONE;
2670 host->dnssec = DS_UNK;
2671 lookup_dnssec_authenticated = NULL;
2672 rc = set_address_from_dns(host, &last, ignore_target_hosts, FALSE,
2673 fully_qualified_name, dnssec_request, dnssec_require);
2674
2675 /* If one or more address records have been found, check that none of them
2676 are local. Since we know the host items all have their IP addresses
2677 inserted, host_scan_for_local_hosts() can only return HOST_FOUND or
2678 HOST_FOUND_LOCAL. We do not need to scan for duplicate IP addresses here,
2679 because set_address_from_dns() removes them. */
2680
2681 if (rc == HOST_FOUND)
2682 rc = host_scan_for_local_hosts(host, &last, removed);
2683 else
2684 if (rc == HOST_IGNORED) rc = HOST_FIND_FAILED; /* No special action */
2685
2686 DEBUG(D_host_lookup)
2687 {
2688 host_item *h;
2689 if (host->address != NULL)
2690 {
2691 if (fully_qualified_name != NULL)
2692 debug_printf("fully qualified name = %s\n", *fully_qualified_name);
2693 for (h = host; h != last->next; h = h->next)
2694 debug_printf("%s %s mx=%d sort=%d %s\n", h->name,
2695 (h->address == NULL)? US"<null>" : h->address, h->mx, h->sort_key,
2696 (h->status >= hstatus_unusable)? US"*" : US"");
2697 }
2698 }
2699
2700 yield = rc;
2701 goto out;
2702 }
2703
2704 /* We have found one or more MX or SRV records. Sort them according to
2705 precedence. Put the data for the first one into the existing host block, and
2706 insert new host_item blocks into the chain for the remainder. For equal
2707 precedences one is supposed to randomize the order. To make this happen, the
2708 sorting is actually done on the MX value * 1000 + a random number. This is put
2709 into a host field called sort_key.
2710
2711 In the case of hosts with both IPv6 and IPv4 addresses, we want to choose the
2712 IPv6 address in preference. At this stage, we don't know what kind of address
2713 the host has. We choose a random number < 500; if later we find an A record
2714 first, we add 500 to the random number. Then for any other address records, we
2715 use random numbers in the range 0-499 for AAAA records and 500-999 for A
2716 records.
2717
2718 At this point we remove any duplicates that point to the same host, retaining
2719 only the one with the lowest precedence. We cannot yet check for precedence
2720 greater than that of the local host, because that test cannot be properly done
2721 until the addresses have been found - an MX record may point to a name for this
2722 host which is not the primary hostname. */
2723
2724 last = NULL; /* Indicates that not even the first item is filled yet */
2725
2726 for (rr = dns_next_rr(&dnsa, &dnss, RESET_ANSWERS);
2727 rr != NULL;
2728 rr = dns_next_rr(&dnsa, &dnss, RESET_NEXT))
2729 {
2730 int precedence;
2731 int weight = 0; /* For SRV records */
2732 int port = PORT_NONE;
2733 uschar *s; /* MUST be unsigned for GETSHORT */
2734 uschar data[256];
2735
2736 if (rr->type != ind_type) continue;
2737 s = rr->data;
2738 GETSHORT(precedence, s); /* Pointer s is advanced */
2739
2740 /* For MX records, we use a random "weight" which causes multiple records of
2741 the same precedence to sort randomly. */
2742
2743 if (ind_type == T_MX)
2744 weight = random_number(500);
2745
2746 /* SRV records are specified with a port and a weight. The weight is used
2747 in a special algorithm. However, to start with, we just use it to order the
2748 records of equal priority (precedence). */
2749
2750 else
2751 {
2752 GETSHORT(weight, s);
2753 GETSHORT(port, s);
2754 }
2755
2756 /* Get the name of the host pointed to. */
2757
2758 (void)dn_expand(dnsa.answer, dnsa.answer + dnsa.answerlen, s,
2759 (DN_EXPAND_ARG4_TYPE)data, sizeof(data));
2760
2761 /* Check that we haven't already got this host on the chain; if we have,
2762 keep only the lower precedence. This situation shouldn't occur, but you
2763 never know what junk might get into the DNS (and this case has been seen on
2764 more than one occasion). */
2765
2766 if (last != NULL) /* This is not the first record */
2767 {
2768 host_item *prev = NULL;
2769
2770 for (h = host; h != last->next; prev = h, h = h->next)
2771 {
2772 if (strcmpic(h->name, data) == 0)
2773 {
2774 DEBUG(D_host_lookup)
2775 debug_printf("discarded duplicate host %s (MX=%d)\n", data,
2776 (precedence > h->mx)? precedence : h->mx);
2777 if (precedence >= h->mx) goto NEXT_MX_RR; /* Skip greater precedence */
2778 if (h == host) /* Override first item */
2779 {
2780 h->mx = precedence;
2781 host->sort_key = precedence * 1000 + weight;
2782 goto NEXT_MX_RR;
2783 }
2784
2785 /* Unwanted host item is not the first in the chain, so we can get
2786 get rid of it by cutting it out. */
2787
2788 prev->next = h->next;
2789 if (h == last) last = prev;
2790 break;
2791 }
2792 }
2793 }
2794
2795 /* If this is the first MX or SRV record, put the data into the existing host
2796 block. Otherwise, add a new block in the correct place; if it has to be
2797 before the first block, copy the first block's data to a new second block. */
2798
2799 if (last == NULL)
2800 {
2801 host->name = string_copy_dnsdomain(data);
2802 host->address = NULL;
2803 host->port = port;
2804 host->mx = precedence;
2805 host->sort_key = precedence * 1000 + weight;
2806 host->status = hstatus_unknown;
2807 host->why = hwhy_unknown;
2808 host->dnssec = dnssec;
2809 last = host;
2810 }
2811
2812 /* Make a new host item and seek the correct insertion place */
2813
2814 else
2815 {
2816 int sort_key = precedence * 1000 + weight;
2817 host_item *next = store_get(sizeof(host_item));
2818 next->name = string_copy_dnsdomain(data);
2819 next->address = NULL;
2820 next->port = port;
2821 next->mx = precedence;
2822 next->sort_key = sort_key;
2823 next->status = hstatus_unknown;
2824 next->why = hwhy_unknown;
2825 next->dnssec = dnssec;
2826 next->last_try = 0;
2827
2828 /* Handle the case when we have to insert before the first item. */
2829
2830 if (sort_key < host->sort_key)
2831 {
2832 host_item htemp;
2833 htemp = *host;
2834 *host = *next;
2835 *next = htemp;
2836 host->next = next;
2837 if (last == host) last = next;
2838 }
2839
2840 /* Else scan down the items we have inserted as part of this exercise;
2841 don't go further. */
2842
2843 else
2844 {
2845 for (h = host; h != last; h = h->next)
2846 {
2847 if (sort_key < h->next->sort_key)
2848 {
2849 next->next = h->next;
2850 h->next = next;
2851 break;
2852 }
2853 }
2854
2855 /* Join on after the last host item that's part of this
2856 processing if we haven't stopped sooner. */
2857
2858 if (h == last)
2859 {
2860 next->next = last->next;
2861 last->next = next;
2862 last = next;
2863 }
2864 }
2865 }
2866
2867 NEXT_MX_RR: continue;
2868 }
2869
2870 /* If the list of hosts was obtained from SRV records, there are two things to
2871 do. First, if there is only one host, and it's name is ".", it means there is
2872 no SMTP service at this domain. Otherwise, we have to sort the hosts of equal
2873 priority according to their weights, using an algorithm that is defined in RFC
2874 2782. The hosts are currently sorted by priority and weight. For each priority
2875 group we have to pick off one host and put it first, and then repeat for any
2876 remaining in the same priority group. */
2877
2878 if (ind_type == T_SRV)
2879 {
2880 host_item **pptr;
2881
2882 if (host == last && host->name[0] == 0)
2883 {
2884 DEBUG(D_host_lookup) debug_printf("the single SRV record is \".\"\n");
2885 yield = HOST_FIND_FAILED;
2886 goto out;
2887 }
2888
2889 DEBUG(D_host_lookup)
2890 {
2891 debug_printf("original ordering of hosts from SRV records:\n");
2892 for (h = host; h != last->next; h = h->next)
2893 debug_printf(" %s P=%d W=%d\n", h->name, h->mx, h->sort_key % 1000);
2894 }
2895
2896 for (pptr = &host, h = host; h != last; pptr = &(h->next), h = h->next)
2897 {
2898 int sum = 0;
2899 host_item *hh;
2900
2901 /* Find the last following host that has the same precedence. At the same
2902 time, compute the sum of the weights and the running totals. These can be
2903 stored in the sort_key field. */
2904
2905 for (hh = h; hh != last; hh = hh->next)
2906 {
2907 int weight = hh->sort_key % 1000; /* was precedence * 1000 + weight */
2908 sum += weight;
2909 hh->sort_key = sum;
2910 if (hh->mx != hh->next->mx) break;
2911 }
2912
2913 /* If there's more than one host at this precedence (priority), we need to
2914 pick one to go first. */
2915
2916 if (hh != h)
2917 {
2918 host_item *hhh;
2919 host_item **ppptr;
2920 int randomizer = random_number(sum + 1);
2921
2922 for (ppptr = pptr, hhh = h;
2923 hhh != hh;
2924 ppptr = &(hhh->next), hhh = hhh->next)
2925 {
2926 if (hhh->sort_key >= randomizer) break;
2927 }
2928
2929 /* hhh now points to the host that should go first; ppptr points to the
2930 place that points to it. Unfortunately, if the start of the minilist is
2931 the start of the entire list, we can't just swap the items over, because
2932 we must not change the value of host, since it is passed in from outside.
2933 One day, this could perhaps be changed.
2934
2935 The special case is fudged by putting the new item *second* in the chain,
2936 and then transferring the data between the first and second items. We
2937 can't just swap the first and the chosen item, because that would mean
2938 that an item with zero weight might no longer be first. */
2939
2940 if (hhh != h)
2941 {
2942 *ppptr = hhh->next; /* Cuts it out of the chain */
2943
2944 if (h == host)
2945 {
2946 host_item temp = *h;
2947 *h = *hhh;
2948 *hhh = temp;
2949 hhh->next = temp.next;
2950 h->next = hhh;
2951 }
2952
2953 else
2954 {
2955 hhh->next = h; /* The rest of the chain follows it */
2956 *pptr = hhh; /* It takes the place of h */
2957 h = hhh; /* It's now the start of this minilist */
2958 }
2959 }
2960 }
2961
2962 /* A host has been chosen to be first at this priority and h now points
2963 to this host. There may be others at the same priority, or others at a
2964 different priority. Before we leave this host, we need to put back a sort
2965 key of the traditional MX kind, in case this host is multihomed, because
2966 the sort key is used for ordering the multiple IP addresses. We do not need
2967 to ensure that these new sort keys actually reflect the order of the hosts,
2968 however. */
2969
2970 h->sort_key = h->mx * 1000 + random_number(500);
2971 } /* Move on to the next host */
2972 }
2973
2974 /* Now we have to find IP addresses for all the hosts. We have ensured above
2975 that the names in all the host items are unique. Before release 4.61 we used to
2976 process records from the additional section in the DNS packet that returned the
2977 MX or SRV records. However, a DNS name server is free to drop any resource
2978 records from the additional section. In theory, this has always been a
2979 potential problem, but it is exacerbated by the advent of IPv6. If a host had
2980 several IPv4 addresses and some were not in the additional section, at least
2981 Exim would try the others. However, if a host had both IPv4 and IPv6 addresses
2982 and all the IPv4 (say) addresses were absent, Exim would try only for a IPv6
2983 connection, and never try an IPv4 address. When there was only IPv4
2984 connectivity, this was a disaster that did in practice occur.
2985
2986 So, from release 4.61 onwards, we always search for A and AAAA records
2987 explicitly. The names shouldn't point to CNAMES, but we use the general lookup
2988 function that handles them, just in case. If any lookup gives a soft error,
2989 change the default yield.
2990
2991 For these DNS lookups, we must disable qualify_single and search_parents;
2992 otherwise invalid host names obtained from MX or SRV records can cause trouble
2993 if they happen to match something local. */
2994
2995 yield = HOST_FIND_FAILED; /* Default yield */
2996 dns_init(FALSE, FALSE, /* Disable qualify_single and search_parents */
2997 dnssec_request || dnssec_require);
2998
2999 for (h = host; h != last->next; h = h->next)
3000 {
3001 if (h->address != NULL) continue; /* Inserted by a multihomed host */
3002 rc = set_address_from_dns(h, &last, ignore_target_hosts, allow_mx_to_ip,
3003 NULL, dnssec_request, dnssec_require);
3004 if (rc != HOST_FOUND)
3005 {
3006 h->status = hstatus_unusable;
3007 if (rc == HOST_FIND_AGAIN)
3008 {
3009 yield = rc;
3010 h->why = hwhy_deferred;
3011 }
3012 else
3013 h->why = (rc == HOST_IGNORED)? hwhy_ignored : hwhy_failed;
3014 }
3015 }
3016
3017 /* Scan the list for any hosts that are marked unusable because they have
3018 been explicitly ignored, and remove them from the list, as if they did not
3019 exist. If we end up with just a single, ignored host, flatten its fields as if
3020 nothing was found. */
3021
3022 if (ignore_target_hosts != NULL)
3023 {
3024 host_item *prev = NULL;
3025 for (h = host; h != last->next; h = h->next)
3026 {
3027 REDO:
3028 if (h->why != hwhy_ignored) /* Non ignored host, just continue */
3029 prev = h;
3030 else if (prev == NULL) /* First host is ignored */
3031 {
3032 if (h != last) /* First is not last */
3033 {
3034 if (h->next == last) last = h; /* Overwrite it with next */
3035 *h = *(h->next); /* and reprocess it. */
3036 goto REDO; /* C should have redo, like Perl */
3037 }
3038 }
3039 else /* Ignored host is not first - */
3040 { /* cut it out */
3041 prev->next = h->next;
3042 if (h == last) last = prev;
3043 }
3044 }
3045
3046 if (host->why == hwhy_ignored) host->address = NULL;
3047 }
3048
3049 /* There is still one complication in the case of IPv6. Although the code above
3050 arranges that IPv6 addresses take precedence over IPv4 addresses for multihomed
3051 hosts, it doesn't do this for addresses that apply to different hosts with the
3052 same MX precedence, because the sorting on MX precedence happens first. So we
3053 have to make another pass to check for this case. We ensure that, within a
3054 single MX preference value, IPv6 addresses come first. This can separate the
3055 addresses of a multihomed host, but that should not matter. */
3056
3057 #if HAVE_IPV6
3058 if (h != last && !disable_ipv6)
3059 {
3060 for (h = host; h != last; h = h->next)
3061 {
3062 host_item temp;
3063 host_item *next = h->next;
3064 if (h->mx != next->mx || /* If next is different MX */
3065 h->address == NULL || /* OR this one is unset */
3066 Ustrchr(h->address, ':') != NULL || /* OR this one is IPv6 */
3067 (next->address != NULL &&
3068 Ustrchr(next->address, ':') == NULL)) /* OR next is IPv4 */
3069 continue; /* move on to next */
3070 temp = *h; /* otherwise, swap */
3071 temp.next = next->next;
3072 *h = *next;
3073 h->next = next;
3074 *next = temp;
3075 }
3076 }
3077 #endif
3078
3079 /* Remove any duplicate IP addresses and then scan the list of hosts for any
3080 whose IP addresses are on the local host. If any are found, all hosts with the
3081 same or higher MX values are removed. However, if the local host has the lowest
3082 numbered MX, then HOST_FOUND_LOCAL is returned. Otherwise, if at least one host
3083 with an IP address is on the list, HOST_FOUND is returned. Otherwise,
3084 HOST_FIND_FAILED is returned, but in this case do not update the yield, as it
3085 might have been set to HOST_FIND_AGAIN just above here. If not, it will already
3086 be HOST_FIND_FAILED. */
3087
3088 host_remove_duplicates(host, &last);
3089 rc = host_scan_for_local_hosts(host, &last, removed);
3090 if (rc != HOST_FIND_FAILED) yield = rc;
3091
3092 DEBUG(D_host_lookup)
3093 {
3094 if (fully_qualified_name != NULL)
3095 debug_printf("fully qualified name = %s\n", *fully_qualified_name);
3096 debug_printf("host_find_bydns yield = %s (%d); returned hosts:\n",
3097 (yield == HOST_FOUND)? "HOST_FOUND" :
3098 (yield == HOST_FOUND_LOCAL)? "HOST_FOUND_LOCAL" :
3099 (yield == HOST_FIND_AGAIN)? "HOST_FIND_AGAIN" :
3100 (yield == HOST_FIND_FAILED)? "HOST_FIND_FAILED" : "?",
3101 yield);
3102 for (h = host; h != last->next; h = h->next)
3103 {
3104 debug_printf(" %s %s MX=%d %s", h->name,
3105 !h->address ? US"<null>" : h->address, h->mx,
3106 h->dnssec == DS_YES ? US"DNSSEC " : US"");
3107 if (h->port != PORT_NONE) debug_printf("port=%d ", h->port);
3108 if (h->status >= hstatus_unusable) debug_printf("*");
3109 debug_printf("\n");
3110 }
3111 }
3112
3113 out:
3114
3115 dns_init(FALSE, FALSE, FALSE); /* clear the dnssec bit for getaddrbyname */
3116 return yield;
3117 }
3118
3119 /*************************************************
3120 **************************************************
3121 * Stand-alone test program *
3122 **************************************************
3123 *************************************************/
3124
3125 #ifdef STAND_ALONE
3126
3127 int main(int argc, char **cargv)
3128 {
3129 host_item h;
3130 int whichrrs = HOST_FIND_BY_MX | HOST_FIND_BY_A;
3131 BOOL byname = FALSE;
3132 BOOL qualify_single = TRUE;
3133 BOOL search_parents = FALSE;
3134 BOOL request_dnssec = FALSE;
3135 BOOL require_dnssec = FALSE;
3136 uschar **argv = USS cargv;
3137 uschar buffer[256];
3138
3139 disable_ipv6 = FALSE;
3140 primary_hostname = US"";
3141 store_pool = POOL_MAIN;
3142 debug_selector = D_host_lookup|D_interface;
3143 debug_file = stdout;
3144 debug_fd = fileno(debug_file);
3145
3146 printf("Exim stand-alone host functions test\n");
3147
3148 host_find_interfaces();
3149 debug_selector = D_host_lookup | D_dns;
3150
3151 if (argc > 1) primary_hostname = argv[1];
3152
3153 /* So that debug level changes can be done first */
3154
3155 dns_init(qualify_single, search_parents, FALSE);
3156
3157 printf("Testing host lookup\n");
3158 printf("> ");
3159 while (Ufgets(buffer, 256, stdin) != NULL)
3160 {
3161 int rc;
3162 int len = Ustrlen(buffer);
3163 uschar *fully_qualified_name;
3164
3165 while (len > 0 && isspace(buffer[len-1])) len--;
3166 buffer[len] = 0;
3167
3168 if (Ustrcmp(buffer, "q") == 0) break;
3169
3170 if (Ustrcmp(buffer, "byname") == 0) byname = TRUE;
3171 else if (Ustrcmp(buffer, "no_byname") == 0) byname = FALSE;
3172 else if (Ustrcmp(buffer, "a_only") == 0) whichrrs = HOST_FIND_BY_A;
3173 else if (Ustrcmp(buffer, "mx_only") == 0) whichrrs = HOST_FIND_BY_MX;
3174 else if (Ustrcmp(buffer, "srv_only") == 0) whichrrs = HOST_FIND_BY_SRV;
3175 else if (Ustrcmp(buffer, "srv+a") == 0)
3176 whichrrs = HOST_FIND_BY_SRV | HOST_FIND_BY_A;
3177 else if (Ustrcmp(buffer, "srv+mx") == 0)
3178 whichrrs = HOST_FIND_BY_SRV | HOST_FIND_BY_MX;
3179 else if (Ustrcmp(buffer, "srv+mx+a") == 0)
3180 whichrrs = HOST_FIND_BY_SRV | HOST_FIND_BY_MX | HOST_FIND_BY_A;
3181 else if (Ustrcmp(buffer, "qualify_single") == 0) qualify_single = TRUE;
3182 else if (Ustrcmp(buffer, "no_qualify_single") == 0) qualify_single = FALSE;
3183 else if (Ustrcmp(buffer, "search_parents") == 0) search_parents = TRUE;
3184 else if (Ustrcmp(buffer, "no_search_parents") == 0) search_parents = FALSE;
3185 else if (Ustrcmp(buffer, "request_dnssec") == 0) request_dnssec = TRUE;
3186 else if (Ustrcmp(buffer, "no_request_dnssec") == 0) request_dnssec = FALSE;
3187 else if (Ustrcmp(buffer, "require_dnssec") == 0) require_dnssec = TRUE;
3188 else if (Ustrcmp(buffer, "no_reqiret_dnssec") == 0) require_dnssec = FALSE;
3189 else if (Ustrcmp(buffer, "test_harness") == 0)
3190 running_in_test_harness = !running_in_test_harness;
3191 else if (Ustrcmp(buffer, "ipv6") == 0) disable_ipv6 = !disable_ipv6;
3192 else if (Ustrcmp(buffer, "res_debug") == 0)
3193 {
3194 _res.options ^= RES_DEBUG;
3195 }
3196 else if (Ustrncmp(buffer, "retrans", 7) == 0)
3197 {
3198 (void)sscanf(CS(buffer+8), "%d", &dns_retrans);
3199 _res.retrans = dns_retrans;
3200 }
3201 else if (Ustrncmp(buffer, "retry", 5) == 0)
3202 {
3203 (void)sscanf(CS(buffer+6), "%d", &dns_retry);
3204 _res.retry = dns_retry;
3205 }
3206 else
3207 {
3208 int flags = whichrrs;
3209 dnssec d;
3210
3211 h.name = buffer;
3212 h.next = NULL;
3213 h.mx = MX_NONE;
3214 h.port = PORT_NONE;
3215 h.status = hstatus_unknown;
3216 h.why = hwhy_unknown;
3217 h.address = NULL;
3218
3219 if (qualify_single) flags |= HOST_FIND_QUALIFY_SINGLE;
3220 if (search_parents) flags |= HOST_FIND_SEARCH_PARENTS;
3221
3222 d.request = request_dnssec ? &h.name : NULL;
3223 d.require = require_dnssec ? &h.name : NULL;
3224
3225 rc = byname
3226 ? host_find_byname(&h, NULL, flags, &fully_qualified_name, TRUE)
3227 : host_find_bydns(&h, NULL, flags, US"smtp", NULL, NULL,
3228 &d, &fully_qualified_name, NULL);
3229
3230 if (rc == HOST_FIND_FAILED) printf("Failed\n");
3231 else if (rc == HOST_FIND_AGAIN) printf("Again\n");
3232 else if (rc == HOST_FOUND_LOCAL) printf("Local\n");
3233 }
3234
3235 printf("\n> ");
3236 }
3237
3238 printf("Testing host_aton\n");
3239 printf("> ");
3240 while (Ufgets(buffer, 256, stdin) != NULL)
3241 {
3242 int i;
3243 int x[4];
3244 int len = Ustrlen(buffer);
3245
3246 while (len > 0 && isspace(buffer[len-1])) len--;
3247 buffer[len] = 0;
3248
3249 if (Ustrcmp(buffer, "q") == 0) break;
3250
3251 len = host_aton(buffer, x);
3252 printf("length = %d ", len);
3253 for (i = 0; i < len; i++)
3254 {
3255 printf("%04x ", (x[i] >> 16) & 0xffff);
3256 printf("%04x ", x[i] & 0xffff);
3257 }
3258 printf("\n> ");
3259 }
3260
3261 printf("\n");
3262
3263 printf("Testing host_name_lookup\n");
3264 printf("> ");
3265 while (Ufgets(buffer, 256, stdin) != NULL)
3266 {
3267 int len = Ustrlen(buffer);
3268 while (len > 0 && isspace(buffer[len-1])) len--;
3269 buffer[len] = 0;
3270 if (Ustrcmp(buffer, "q") == 0) break;
3271 sender_host_address = buffer;
3272 sender_host_name = NULL;
3273 sender_host_aliases = NULL;
3274 host_lookup_msg = US"";
3275 host_lookup_failed = FALSE;
3276 if (host_name_lookup() == FAIL) /* Debug causes printing */
3277 printf("Lookup failed:%s\n", host_lookup_msg);
3278 printf("\n> ");
3279 }
3280
3281 printf("\n");
3282
3283 return 0;
3284 }
3285 #endif /* STAND_ALONE */
3286
3287 /* vi: aw ai sw=2
3288 */
3289 /* End of host.c */