1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
5 /* Copyright (c) University of Cambridge 1995 - 2012 */
6 /* See the file NOTICE for conditions of use and distribution. */
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
20 /* Static variable for preserving the list of interface addresses in case it is
21 used more than once. */
23 static ip_address_item *local_interface_data = NULL;
26 #ifdef USE_INET_NTOA_FIX
27 /*************************************************
28 * Replacement for broken inet_ntoa() *
29 *************************************************/
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,
39 as seen in comp.sys.sgi.admin
41 August 2005: Apparently this is also needed for AIX systems; USE_INET_NTOA_FIX
42 should now be set for them as well.
44 Arguments: sa an in_addr structure
45 Returns: pointer to static text string
49 inet_ntoa(struct in_addr sa)
51 static uschar addr[20];
52 sprintf(addr, "%d.%d.%d.%d",
63 /*************************************************
64 * Random number generator *
65 *************************************************/
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.
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.
75 limit: one more than the largest number required
77 Returns: a pseudo-random number in the range 0 to limit-1
81 random_number(int limit)
87 if (running_in_test_harness) random_seed = 42; else
89 int p = (int)getpid();
90 random_seed = (int)time(NULL) ^ ((p << 16) | p);
93 random_seed = 1103515245 * random_seed + 12345;
94 return (unsigned int)(random_seed >> 16) % limit;
99 /*************************************************
100 * Replace gethostbyname() when testing *
101 *************************************************/
103 /* This function is called instead of gethostbyname(), gethostbyname2(), or
104 getipnodebyname() when running in the test harness. It recognizes the name
105 "manyhome.test.ex" and generates a humungous number of IP addresses. It also
106 recognizes an unqualified "localhost" and forces it to the appropriate loopback
107 address. IP addresses are treated as literals. For other names, it uses the DNS
108 to find the host name. In the test harness, this means it will access only the
112 name the host name or a textual IP address
113 af AF_INET or AF_INET6
114 error_num where to put an error code:
115 HOST_NOT_FOUND/TRY_AGAIN/NO_RECOVERY/NO_DATA
117 Returns: a hostent structure or NULL for an error
120 static struct hostent *
121 host_fake_gethostbyname(const uschar *name, int af, int *error_num)
124 int alen = (af == AF_INET)? sizeof(struct in_addr):sizeof(struct in6_addr);
126 int alen = sizeof(struct in_addr);
130 const uschar *lname = name;
133 struct hostent *yield;
139 debug_printf("using host_fake_gethostbyname for %s (%s)\n", name,
140 (af == AF_INET)? "IPv4" : "IPv6");
142 /* Handle the name that needs a vast number of IP addresses */
144 if (Ustrcmp(name, "manyhome.test.ex") == 0 && af == AF_INET)
147 yield = store_get(sizeof(struct hostent));
148 alist = store_get(2049 * sizeof(char *));
149 adds = store_get(2048 * alen);
150 yield->h_name = CS name;
151 yield->h_aliases = NULL;
152 yield->h_addrtype = af;
153 yield->h_length = alen;
154 yield->h_addr_list = CSS alist;
155 for (i = 104; i <= 111; i++)
157 for (j = 0; j <= 255; j++)
170 /* Handle unqualified "localhost" */
172 if (Ustrcmp(name, "localhost") == 0)
173 lname = (af == AF_INET)? US"127.0.0.1" : US"::1";
175 /* Handle a literal IP address */
177 ipa = string_is_ip_address(lname, NULL);
180 if ((ipa == 4 && af == AF_INET) ||
181 (ipa == 6 && af == AF_INET6))
185 yield = store_get(sizeof(struct hostent));
186 alist = store_get(2 * sizeof(char *));
187 adds = store_get(alen);
188 yield->h_name = CS name;
189 yield->h_aliases = NULL;
190 yield->h_addrtype = af;
191 yield->h_length = alen;
192 yield->h_addr_list = CSS alist;
194 n = host_aton(lname, x);
195 for (i = 0; i < n; i++)
198 *adds++ = (y >> 24) & 255;
199 *adds++ = (y >> 16) & 255;
200 *adds++ = (y >> 8) & 255;
206 /* Wrong kind of literal address */
210 *error_num = HOST_NOT_FOUND;
215 /* Handle a host name */
219 int type = (af == AF_INET)? T_A:T_AAAA;
220 int rc = dns_lookup(&dnsa, lname, type, NULL);
223 lookup_dnssec_authenticated = NULL;
227 case DNS_SUCCEED: break;
228 case DNS_NOMATCH: *error_num = HOST_NOT_FOUND; return NULL;
229 case DNS_NODATA: *error_num = NO_DATA; return NULL;
230 case DNS_AGAIN: *error_num = TRY_AGAIN; return NULL;
232 case DNS_FAIL: *error_num = NO_RECOVERY; return NULL;
235 for (rr = dns_next_rr(&dnsa, &dnss, RESET_ANSWERS);
237 rr = dns_next_rr(&dnsa, &dnss, RESET_NEXT))
239 if (rr->type == type) count++;
242 yield = store_get(sizeof(struct hostent));
243 alist = store_get((count + 1) * sizeof(char **));
244 adds = store_get(count *alen);
246 yield->h_name = CS name;
247 yield->h_aliases = NULL;
248 yield->h_addrtype = af;
249 yield->h_length = alen;
250 yield->h_addr_list = CSS alist;
252 for (rr = dns_next_rr(&dnsa, &dnss, RESET_ANSWERS);
254 rr = dns_next_rr(&dnsa, &dnss, RESET_NEXT))
259 if (rr->type != type) continue;
260 da = dns_address_from_rr(&dnsa, rr);
262 n = host_aton(da->address, x);
263 for (i = 0; i < n; i++)
266 *adds++ = (y >> 24) & 255;
267 *adds++ = (y >> 16) & 255;
268 *adds++ = (y >> 8) & 255;
280 /*************************************************
281 * Build chain of host items from list *
282 *************************************************/
284 /* This function builds a chain of host items from a textual list of host
285 names. It does not do any lookups. If randomize is true, the chain is build in
286 a randomized order. There may be multiple groups of independently randomized
287 hosts; they are delimited by a host name consisting of just "+".
290 anchor anchor for the chain
292 randomize TRUE for randomizing
298 host_build_hostlist(host_item **anchor, const uschar *list, BOOL randomize)
301 int fake_mx = MX_NONE; /* This value is actually -1 */
304 if (list == NULL) return;
305 if (randomize) fake_mx--; /* Start at -2 for randomizing */
309 while ((name = string_nextinlist(&list, &sep, NULL, 0)) != NULL)
313 if (name[0] == '+' && name[1] == 0) /* "+" delimits a randomized group */
314 { /* ignore if not randomizing */
315 if (randomize) fake_mx--;
319 h = store_get(sizeof(host_item));
324 h->sort_key = randomize? (-fake_mx)*1000 + random_number(1000) : 0;
325 h->status = hstatus_unknown;
326 h->why = hwhy_unknown;
336 host_item *hh = *anchor;
337 if (h->sort_key < hh->sort_key)
344 while (hh->next != NULL && h->sort_key >= (hh->next)->sort_key)
357 /*************************************************
358 * Extract port from address string *
359 *************************************************/
361 /* In the spool file, and in the -oMa and -oMi options, a host plus port is
362 given as an IP address followed by a dot and a port number. This function
365 An alternative format for the -oMa and -oMi options is [ip address]:port which
366 is what Exim 4 uses for output, because it seems to becoming commonly used,
367 whereas the dot form confuses some programs/people. So we recognize that form
371 address points to the string; if there is a port, the '.' in the string
372 is overwritten with zero to terminate the address; if the string
373 is in the [xxx]:ppp format, the address is shifted left and the
376 Returns: 0 if there is no port, else the port number. If there's a syntax
377 error, leave the incoming address alone, and return 0.
381 host_address_extract_port(uschar *address)
386 /* Handle the "bracketed with colon on the end" format */
390 uschar *rb = address + 1;
391 while (*rb != 0 && *rb != ']') rb++;
392 if (*rb++ == 0) return 0; /* Missing ]; leave invalid address */
395 port = Ustrtol(rb + 1, &endptr, 10);
396 if (*endptr != 0) return 0; /* Invalid port; leave invalid address */
398 else if (*rb != 0) return 0; /* Bad syntax; leave invalid address */
399 memmove(address, address + 1, rb - address - 2);
403 /* Handle the "dot on the end" format */
407 int skip = -3; /* Skip 3 dots in IPv4 addresses */
409 while (*(++address) != 0)
412 if (ch == ':') skip = 0; /* Skip 0 dots in IPv6 addresses */
413 else if (ch == '.' && skip++ >= 0) break;
415 if (*address == 0) return 0;
416 port = Ustrtol(address + 1, &endptr, 10);
417 if (*endptr != 0) return 0; /* Invalid port; leave invalid address */
425 /*************************************************
426 * Get port from a host item's name *
427 *************************************************/
429 /* This function is called when finding the IP address for a host that is in a
430 list of hosts explicitly configured, such as in the manualroute router, or in a
431 fallback hosts list. We see if there is a port specification at the end of the
432 host name, and if so, remove it. A minimum length of 3 is required for the
433 original name; nothing shorter is recognized as having a port.
435 We test for a name ending with a sequence of digits; if preceded by colon we
436 have a port if the character before the colon is ] and the name starts with [
437 or if there are no other colons in the name (i.e. it's not an IPv6 address).
439 Arguments: pointer to the host item
440 Returns: a port number or PORT_NONE
444 host_item_get_port(host_item *h)
448 int len = Ustrlen(h->name);
450 if (len < 3 || (p = h->name + len - 1, !isdigit(*p))) return PORT_NONE;
452 /* Extract potential port number */
457 while (p > h->name + 1 && isdigit(*p))
459 port += (*p-- - '0') * x;
463 /* The smallest value of p at this point is h->name + 1. */
465 if (*p != ':') return PORT_NONE;
467 if (p[-1] == ']' && h->name[0] == '[')
468 h->name = string_copyn(h->name + 1, p - h->name - 2);
469 else if (Ustrchr(h->name, ':') == p)
470 h->name = string_copyn(h->name, p - h->name);
471 else return PORT_NONE;
473 DEBUG(D_route|D_host_lookup) debug_printf("host=%s port=%d\n", h->name, port);
479 #ifndef STAND_ALONE /* Omit when standalone testing */
481 /*************************************************
482 * Build sender_fullhost and sender_rcvhost *
483 *************************************************/
485 /* This function is called when sender_host_name and/or sender_helo_name
486 have been set. Or might have been set - for a local message read off the spool
487 they won't be. In that case, do nothing. Otherwise, set up the fullhost string
490 (a) No sender_host_name or sender_helo_name: "[ip address]"
491 (b) Just sender_host_name: "host_name [ip address]"
492 (c) Just sender_helo_name: "(helo_name) [ip address]" unless helo is IP
493 in which case: "[ip address}"
494 (d) The two are identical: "host_name [ip address]" includes helo = IP
495 (e) The two are different: "host_name (helo_name) [ip address]"
497 If log_incoming_port is set, the sending host's port number is added to the IP
500 This function also builds sender_rcvhost for use in Received: lines, whose
501 syntax is a bit different. This value also includes the RFC 1413 identity.
502 There wouldn't be two different variables if I had got all this right in the
505 Because this data may survive over more than one incoming SMTP message, it has
506 to be in permanent store.
513 host_build_sender_fullhost(void)
515 BOOL show_helo = TRUE;
518 int old_pool = store_pool;
520 if (sender_host_address == NULL) return;
522 store_pool = POOL_PERM;
524 /* Set up address, with or without the port. After discussion, it seems that
525 the only format that doesn't cause trouble is [aaaa]:pppp. However, we can't
526 use this directly as the first item for Received: because it ain't an RFC 2822
529 address = string_sprintf("[%s]:%d", sender_host_address, sender_host_port);
530 if ((log_extra_selector & LX_incoming_port) == 0 || sender_host_port <= 0)
531 *(Ustrrchr(address, ':')) = 0;
533 /* If there's no EHLO/HELO data, we can't show it. */
535 if (sender_helo_name == NULL) show_helo = FALSE;
537 /* If HELO/EHLO was followed by an IP literal, it's messy because of two
538 features of IPv6. Firstly, there's the "IPv6:" prefix (Exim is liberal and
539 doesn't require this, for historical reasons). Secondly, IPv6 addresses may not
540 be given in canonical form, so we have to canonicize them before comparing. As
541 it happens, the code works for both IPv4 and IPv6. */
543 else if (sender_helo_name[0] == '[' &&
544 sender_helo_name[(len=Ustrlen(sender_helo_name))-1] == ']')
549 if (strncmpic(sender_helo_name + 1, US"IPv6:", 5) == 0) offset += 5;
550 if (strncmpic(sender_helo_name + 1, US"IPv4:", 5) == 0) offset += 5;
552 helo_ip = string_copyn(sender_helo_name + offset, len - offset - 1);
554 if (string_is_ip_address(helo_ip, NULL) != 0)
558 uschar ipx[48], ipy[48]; /* large enough for full IPv6 */
560 sizex = host_aton(helo_ip, x);
561 sizey = host_aton(sender_host_address, y);
563 (void)host_nmtoa(sizex, x, -1, ipx, ':');
564 (void)host_nmtoa(sizey, y, -1, ipy, ':');
566 if (strcmpic(ipx, ipy) == 0) show_helo = FALSE;
570 /* Host name is not verified */
572 if (sender_host_name == NULL)
574 uschar *portptr = Ustrstr(address, "]:");
577 int adlen; /* Sun compiler doesn't like ++ in initializers */
579 adlen = (portptr == NULL)? Ustrlen(address) : (++portptr - address);
580 sender_fullhost = (sender_helo_name == NULL)? address :
581 string_sprintf("(%s) %s", sender_helo_name, address);
583 sender_rcvhost = string_cat(NULL, &size, &ptr, address, adlen);
585 if (sender_ident != NULL || show_helo || portptr != NULL)
588 sender_rcvhost = string_cat(sender_rcvhost, &size, &ptr, US" (", 2);
592 sender_rcvhost = string_append(sender_rcvhost, &size, &ptr, 2, US"port=",
596 sender_rcvhost = string_append(sender_rcvhost, &size, &ptr, 2,
597 (firstptr == ptr)? US"helo=" : US" helo=", sender_helo_name);
599 if (sender_ident != NULL)
600 sender_rcvhost = string_append(sender_rcvhost, &size, &ptr, 2,
601 (firstptr == ptr)? US"ident=" : US" ident=", sender_ident);
603 sender_rcvhost = string_cat(sender_rcvhost, &size, &ptr, US")", 1);
606 sender_rcvhost[ptr] = 0; /* string_cat() always leaves room */
608 /* Release store, because string_cat allocated a minimum of 100 bytes that
609 are rarely completely used. */
611 store_reset(sender_rcvhost + ptr + 1);
614 /* Host name is known and verified. Unless we've already found that the HELO
615 data matches the IP address, compare it with the name. */
619 if (show_helo && strcmpic(sender_host_name, sender_helo_name) == 0)
624 sender_fullhost = string_sprintf("%s (%s) %s", sender_host_name,
625 sender_helo_name, address);
626 sender_rcvhost = (sender_ident == NULL)?
627 string_sprintf("%s (%s helo=%s)", sender_host_name,
628 address, sender_helo_name) :
629 string_sprintf("%s\n\t(%s helo=%s ident=%s)", sender_host_name,
630 address, sender_helo_name, sender_ident);
634 sender_fullhost = string_sprintf("%s %s", sender_host_name, address);
635 sender_rcvhost = (sender_ident == NULL)?
636 string_sprintf("%s (%s)", sender_host_name, address) :
637 string_sprintf("%s (%s ident=%s)", sender_host_name, address,
642 store_pool = old_pool;
644 DEBUG(D_host_lookup) debug_printf("sender_fullhost = %s\n", sender_fullhost);
645 DEBUG(D_host_lookup) debug_printf("sender_rcvhost = %s\n", sender_rcvhost);
650 /*************************************************
651 * Build host+ident message *
652 *************************************************/
654 /* Used when logging rejections and various ACL and SMTP incidents. The text
655 return depends on whether sender_fullhost and sender_ident are set or not:
657 no ident, no host => U=unknown
658 no ident, host set => H=sender_fullhost
659 ident set, no host => U=ident
660 ident set, host set => H=sender_fullhost U=ident
663 useflag TRUE if first item to be flagged (H= or U=); if there are two
664 items, the second is always flagged
666 Returns: pointer to a string in big_buffer
670 host_and_ident(BOOL useflag)
672 if (sender_fullhost == NULL)
674 (void)string_format(big_buffer, big_buffer_size, "%s%s", useflag? "U=" : "",
675 (sender_ident == NULL)? US"unknown" : sender_ident);
679 uschar *flag = useflag? US"H=" : US"";
680 uschar *iface = US"";
681 if ((log_extra_selector & LX_incoming_interface) != 0 &&
682 interface_address != NULL)
683 iface = string_sprintf(" I=[%s]:%d", interface_address, interface_port);
684 if (sender_ident == NULL)
685 (void)string_format(big_buffer, big_buffer_size, "%s%s%s",
686 flag, sender_fullhost, iface);
688 (void)string_format(big_buffer, big_buffer_size, "%s%s%s U=%s",
689 flag, sender_fullhost, iface, sender_ident);
694 #endif /* STAND_ALONE */
699 /*************************************************
700 * Build list of local interfaces *
701 *************************************************/
703 /* This function interprets the contents of the local_interfaces or
704 extra_local_interfaces options, and creates an ip_address_item block for each
705 item on the list. There is no special interpretation of any IP addresses; in
706 particular, 0.0.0.0 and ::0 are returned without modification. If any address
707 includes a port, it is set in the block. Otherwise the port value is set to
712 name the name of the option being expanded
714 Returns: a chain of ip_address_items, each containing to a textual
715 version of an IP address, and a port number (host order) or
716 zero if no port was given with the address
720 host_build_ifacelist(const uschar *list, uschar *name)
725 ip_address_item *yield = NULL;
726 ip_address_item *last = NULL;
727 ip_address_item *next;
729 while ((s = string_nextinlist(&list, &sep, buffer, sizeof(buffer))) != NULL)
732 int port = host_address_extract_port(s); /* Leaves just the IP address */
733 if ((ipv = string_is_ip_address(s, NULL)) == 0)
734 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "Malformed IP address \"%s\" in %s",
737 /* Skip IPv6 addresses if IPv6 is disabled. */
739 if (disable_ipv6 && ipv == 6) continue;
741 /* This use of strcpy() is OK because we have checked that s is a valid IP
742 address above. The field in the ip_address_item is large enough to hold an
745 next = store_get(sizeof(ip_address_item));
747 Ustrcpy(next->address, s);
749 next->v6_include_v4 = FALSE;
751 if (yield == NULL) yield = last = next; else
765 /*************************************************
766 * Find addresses on local interfaces *
767 *************************************************/
769 /* This function finds the addresses of local IP interfaces. These are used
770 when testing for routing to the local host. As the function may be called more
771 than once, the list is preserved in permanent store, pointed to by a static
772 variable, to save doing the work more than once per process.
774 The generic list of interfaces is obtained by calling host_build_ifacelist()
775 for local_interfaces and extra_local_interfaces. This list scanned to remove
776 duplicates (which may exist with different ports - not relevant here). If
777 either of the wildcard IP addresses (0.0.0.0 and ::0) are encountered, they are
778 replaced by the appropriate (IPv4 or IPv6) list of actual local interfaces,
779 obtained from os_find_running_interfaces().
782 Returns: a chain of ip_address_items, each containing to a textual
783 version of an IP address; the port numbers are not relevant
787 /* First, a local subfunction to add an interface to a list in permanent store,
788 but only if there isn't a previous copy of that address on the list. */
790 static ip_address_item *
791 add_unique_interface(ip_address_item *list, ip_address_item *ipa)
793 ip_address_item *ipa2;
794 for (ipa2 = list; ipa2 != NULL; ipa2 = ipa2->next)
795 if (Ustrcmp(ipa2->address, ipa->address) == 0) return list;
796 ipa2 = store_get_perm(sizeof(ip_address_item));
803 /* This is the globally visible function */
806 host_find_interfaces(void)
808 ip_address_item *running_interfaces = NULL;
810 if (local_interface_data == NULL)
812 void *reset_item = store_get(0);
813 ip_address_item *dlist = host_build_ifacelist(CUS local_interfaces,
814 US"local_interfaces");
815 ip_address_item *xlist = host_build_ifacelist(CUS extra_local_interfaces,
816 US"extra_local_interfaces");
817 ip_address_item *ipa;
819 if (dlist == NULL) dlist = xlist; else
821 for (ipa = dlist; ipa->next != NULL; ipa = ipa->next);
825 for (ipa = dlist; ipa != NULL; ipa = ipa->next)
827 if (Ustrcmp(ipa->address, "0.0.0.0") == 0 ||
828 Ustrcmp(ipa->address, "::0") == 0)
830 ip_address_item *ipa2;
831 BOOL ipv6 = ipa->address[0] == ':';
832 if (running_interfaces == NULL)
833 running_interfaces = os_find_running_interfaces();
834 for (ipa2 = running_interfaces; ipa2 != NULL; ipa2 = ipa2->next)
836 if ((Ustrchr(ipa2->address, ':') != NULL) == ipv6)
837 local_interface_data = add_unique_interface(local_interface_data,
843 local_interface_data = add_unique_interface(local_interface_data, ipa);
846 debug_printf("Configured local interface: address=%s", ipa->address);
847 if (ipa->port != 0) debug_printf(" port=%d", ipa->port);
852 store_reset(reset_item);
855 return local_interface_data;
862 /*************************************************
863 * Convert network IP address to text *
864 *************************************************/
866 /* Given an IPv4 or IPv6 address in binary, convert it to a text
867 string and return the result in a piece of new store. The address can
868 either be given directly, or passed over in a sockaddr structure. Note
869 that this isn't the converse of host_aton() because of byte ordering
870 differences. See host_nmtoa() below.
873 type if < 0 then arg points to a sockaddr, else
874 either AF_INET or AF_INET6
875 arg points to a sockaddr if type is < 0, or
876 points to an IPv4 address (32 bits), or
877 points to an IPv6 address (128 bits),
878 in both cases, in network byte order
879 buffer if NULL, the result is returned in gotten store;
880 else points to a buffer to hold the answer
881 portptr points to where to put the port number, if non NULL; only
884 Returns: pointer to character string
888 host_ntoa(int type, const void *arg, uschar *buffer, int *portptr)
892 /* The new world. It is annoying that we have to fish out the address from
893 different places in the block, depending on what kind of address it is. It
894 is also a pain that inet_ntop() returns a const uschar *, whereas the IPv4
895 function inet_ntoa() returns just uschar *, and some picky compilers insist
896 on warning if one assigns a const uschar * to a uschar *. Hence the casts. */
899 uschar addr_buffer[46];
902 int family = ((struct sockaddr *)arg)->sa_family;
903 if (family == AF_INET6)
905 struct sockaddr_in6 *sk = (struct sockaddr_in6 *)arg;
906 yield = (uschar *)inet_ntop(family, &(sk->sin6_addr), CS addr_buffer,
907 sizeof(addr_buffer));
908 if (portptr != NULL) *portptr = ntohs(sk->sin6_port);
912 struct sockaddr_in *sk = (struct sockaddr_in *)arg;
913 yield = (uschar *)inet_ntop(family, &(sk->sin_addr), CS addr_buffer,
914 sizeof(addr_buffer));
915 if (portptr != NULL) *portptr = ntohs(sk->sin_port);
920 yield = (uschar *)inet_ntop(type, arg, CS addr_buffer, sizeof(addr_buffer));
923 /* If the result is a mapped IPv4 address, show it in V4 format. */
925 if (Ustrncmp(yield, "::ffff:", 7) == 0) yield += 7;
927 #else /* HAVE_IPV6 */
933 yield = US inet_ntoa(((struct sockaddr_in *)arg)->sin_addr);
934 if (portptr != NULL) *portptr = ntohs(((struct sockaddr_in *)arg)->sin_port);
937 yield = US inet_ntoa(*((struct in_addr *)arg));
940 /* If there is no buffer, put the string into some new store. */
942 if (buffer == NULL) return string_copy(yield);
944 /* Callers of this function with a non-NULL buffer must ensure that it is
945 large enough to hold an IPv6 address, namely, at least 46 bytes. That's what
946 makes this use of strcpy() OK. */
948 Ustrcpy(buffer, yield);
955 /*************************************************
956 * Convert address text to binary *
957 *************************************************/
959 /* Given the textual form of an IP address, convert it to binary in an
960 array of ints. IPv4 addresses occupy one int; IPv6 addresses occupy 4 ints.
961 The result has the first byte in the most significant byte of the first int. In
962 other words, the result is not in network byte order, but in host byte order.
963 As a result, this is not the converse of host_ntoa(), which expects network
964 byte order. See host_nmtoa() below.
967 address points to the textual address, checked for syntax
968 bin points to an array of 4 ints
970 Returns: the number of ints used
974 host_aton(const uschar *address, int *bin)
979 /* Handle IPv6 address, which may end with an IPv4 address. It may also end
980 with a "scope", introduced by a percent sign. This code is NOT enclosed in #if
981 HAVE_IPV6 in order that IPv6 addresses are recognized even if IPv6 is not
984 if (Ustrchr(address, ':') != NULL)
986 const uschar *p = address;
987 const uschar *component[8];
988 BOOL ipv4_ends = FALSE;
994 /* If the address starts with a colon, it will start with two colons.
995 Just lose the first one, which will leave a null first component. */
999 /* Split the address into components separated by colons. The input address
1000 is supposed to be checked for syntax. There was a case where this was
1001 overlooked; to guard against that happening again, check here and crash if
1002 there are too many components. */
1004 while (*p != 0 && *p != '%')
1006 int len = Ustrcspn(p, ":%");
1007 if (len == 0) nulloffset = ci;
1008 if (ci > 7) log_write(0, LOG_MAIN|LOG_PANIC_DIE,
1009 "Internal error: invalid IPv6 address \"%s\" passed to host_aton()",
1011 component[ci++] = p;
1016 /* If the final component contains a dot, it is a trailing v4 address.
1017 As the syntax is known to be checked, just set up for a trailing
1018 v4 address and restrict the v6 part to 6 components. */
1020 if (Ustrchr(component[ci-1], '.') != NULL)
1022 address = component[--ci];
1028 /* If there are fewer than 6 or 8 components, we have to insert some
1029 more empty ones in the middle. */
1033 int insert_count = v6count - ci;
1034 for (i = v6count-1; i > nulloffset + insert_count; i--)
1035 component[i] = component[i - insert_count];
1036 while (i > nulloffset) component[i--] = US"";
1039 /* Now turn the components into binary in pairs and bung them
1040 into the vector of ints. */
1042 for (i = 0; i < v6count; i += 2)
1043 bin[i/2] = (Ustrtol(component[i], NULL, 16) << 16) +
1044 Ustrtol(component[i+1], NULL, 16);
1046 /* If there was no terminating v4 component, we are done. */
1048 if (!ipv4_ends) return 4;
1051 /* Handle IPv4 address */
1053 (void)sscanf(CS address, "%d.%d.%d.%d", x, x+1, x+2, x+3);
1054 bin[v4offset] = (x[0] << 24) + (x[1] << 16) + (x[2] << 8) + x[3];
1059 /*************************************************
1060 * Apply mask to an IP address *
1061 *************************************************/
1063 /* Mask an address held in 1 or 4 ints, with the ms bit in the ms bit of the
1067 count the number of ints
1068 binary points to the ints to be masked
1069 mask the count of ms bits to leave, or -1 if no masking
1075 host_mask(int count, int *binary, int mask)
1078 if (mask < 0) mask = 99999;
1079 for (i = 0; i < count; i++)
1082 if (mask == 0) wordmask = 0;
1085 wordmask = (-1) << (32 - mask);
1093 binary[i] &= wordmask;
1100 /*************************************************
1101 * Convert masked IP address in ints to text *
1102 *************************************************/
1104 /* We can't use host_ntoa() because it assumes the binary values are in network
1105 byte order, and these are the result of host_aton(), which puts them in ints in
1106 host byte order. Also, we really want IPv6 addresses to be in a canonical
1107 format, so we output them with no abbreviation. In a number of cases we can't
1108 use the normal colon separator in them because it terminates keys in lsearch
1109 files, so we want to use dot instead. There's an argument that specifies what
1110 to use for IPv6 addresses.
1113 count 1 or 4 (number of ints)
1114 binary points to the ints
1115 mask mask value; if < 0 don't add to result
1116 buffer big enough to hold the result
1117 sep component separator character for IPv6 addresses
1119 Returns: the number of characters placed in buffer, not counting
1124 host_nmtoa(int count, int *binary, int mask, uschar *buffer, int sep)
1127 uschar *tt = buffer;
1132 for (i = 24; i >= 0; i -= 8)
1134 sprintf(CS tt, "%d.", (j >> i) & 255);
1140 for (i = 0; i < 4; i++)
1143 sprintf(CS tt, "%04x%c%04x%c", (j >> 16) & 0xffff, sep, j & 0xffff, sep);
1148 tt--; /* lose final separator */
1154 sprintf(CS tt, "/%d", mask);
1163 /*************************************************
1164 * Check port for tls_on_connect *
1165 *************************************************/
1167 /* This function checks whether a given incoming port is configured for tls-
1168 on-connect. It is called from the daemon and from inetd handling. If the global
1169 option tls_on_connect is already set, all ports operate this way. Otherwise, we
1170 check the tls_on_connect_ports option for a list of ports.
1172 Argument: a port number
1173 Returns: TRUE or FALSE
1177 host_is_tls_on_connect_port(int port)
1181 const uschar *list = tls_in.on_connect_ports;
1185 if (tls_in.on_connect) return TRUE;
1187 while ((s = string_nextinlist(&list, &sep, buffer, sizeof(buffer))))
1188 if (Ustrtol(s, &end, 10) == port)
1196 /*************************************************
1197 * Check whether host is in a network *
1198 *************************************************/
1200 /* This function checks whether a given IP address matches a pattern that
1201 represents either a single host, or a network (using CIDR notation). The caller
1202 of this function must check the syntax of the arguments before calling it.
1205 host string representation of the ip-address to check
1206 net string representation of the network, with optional CIDR mask
1207 maskoffset offset to the / that introduces the mask in the key
1208 zero if there is no mask
1211 TRUE the host is inside the network
1212 FALSE the host is NOT inside the network
1216 host_is_in_net(const uschar *host, const uschar *net, int maskoffset)
1222 int size = host_aton(net, address);
1225 /* No mask => all bits to be checked */
1227 if (maskoffset == 0) mlen = 99999; /* Big number */
1228 else mlen = Uatoi(net + maskoffset + 1);
1230 /* Convert the incoming address to binary. */
1232 insize = host_aton(host, incoming);
1234 /* Convert IPv4 addresses given in IPv6 compatible mode, which represent
1235 connections from IPv4 hosts to IPv6 hosts, that is, addresses of the form
1236 ::ffff:<v4address>, to IPv4 format. */
1238 if (insize == 4 && incoming[0] == 0 && incoming[1] == 0 &&
1239 incoming[2] == 0xffff)
1242 incoming[0] = incoming[3];
1245 /* No match if the sizes don't agree. */
1247 if (insize != size) return FALSE;
1249 /* Else do the masked comparison. */
1251 for (i = 0; i < size; i++)
1254 if (mlen == 0) mask = 0;
1257 mask = (-1) << (32 - mlen);
1265 if ((incoming[i] & mask) != (address[i] & mask)) return FALSE;
1273 /*************************************************
1274 * Scan host list for local hosts *
1275 *************************************************/
1277 /* Scan through a chain of addresses and check whether any of them is the
1278 address of an interface on the local machine. If so, remove that address and
1279 any previous ones with the same MX value, and all subsequent ones (which will
1280 have greater or equal MX values) from the chain. Note: marking them as unusable
1281 is NOT the right thing to do because it causes the hosts not to be used for
1282 other domains, for which they may well be correct.
1284 The hosts may be part of a longer chain; we only process those between the
1285 initial pointer and the "last" pointer.
1287 There is also a list of "pseudo-local" host names which are checked against the
1288 host names. Any match causes that host item to be treated the same as one which
1289 matches a local IP address.
1291 If the very first host is a local host, then all MX records had a precedence
1292 greater than or equal to that of the local host. Either there's a problem in
1293 the DNS, or an apparently remote name turned out to be an abbreviation for the
1294 local host. Give a specific return code, and let the caller decide what to do.
1295 Otherwise, give a success code if at least one host address has been found.
1298 host pointer to the first host in the chain
1299 lastptr pointer to pointer to the last host in the chain (may be updated)
1300 removed if not NULL, set TRUE if some local addresses were removed
1304 HOST_FOUND if there is at least one host with an IP address on the chain
1305 and an MX value less than any MX value associated with the
1307 HOST_FOUND_LOCAL if a local host is among the lowest-numbered MX hosts; when
1308 the host addresses were obtained from A records or
1309 gethostbyname(), the MX values are set to -1.
1310 HOST_FIND_FAILED if no valid hosts with set IP addresses were found
1314 host_scan_for_local_hosts(host_item *host, host_item **lastptr, BOOL *removed)
1316 int yield = HOST_FIND_FAILED;
1317 host_item *last = *lastptr;
1318 host_item *prev = NULL;
1321 if (removed != NULL) *removed = FALSE;
1323 if (local_interface_data == NULL) local_interface_data = host_find_interfaces();
1325 for (h = host; h != last->next; h = h->next)
1328 if (hosts_treat_as_local != NULL)
1331 const uschar *save = deliver_domain;
1332 deliver_domain = h->name; /* set $domain */
1333 rc = match_isinlist(string_copylc(h->name), CUSS &hosts_treat_as_local, 0,
1334 &domainlist_anchor, NULL, MCL_DOMAIN, TRUE, NULL);
1335 deliver_domain = save;
1336 if (rc == OK) goto FOUND_LOCAL;
1340 /* It seems that on many operating systems, 0.0.0.0 is treated as a synonym
1341 for 127.0.0.1 and refers to the local host. We therefore force it always to
1342 be treated as local. */
1344 if (h->address != NULL)
1346 ip_address_item *ip;
1347 if (Ustrcmp(h->address, "0.0.0.0") == 0) goto FOUND_LOCAL;
1348 for (ip = local_interface_data; ip != NULL; ip = ip->next)
1349 if (Ustrcmp(h->address, ip->address) == 0) goto FOUND_LOCAL;
1350 yield = HOST_FOUND; /* At least one remote address has been found */
1353 /* Update prev to point to the last host item before any that have
1354 the same MX value as the one we have just considered. */
1356 if (h->next == NULL || h->next->mx != h->mx) prev = h;
1359 return yield; /* No local hosts found: return HOST_FOUND or HOST_FIND_FAILED */
1361 /* A host whose IP address matches a local IP address, or whose name matches
1362 something in hosts_treat_as_local has been found. */
1368 HDEBUG(D_host_lookup) debug_printf((h->mx >= 0)?
1369 "local host has lowest MX\n" :
1370 "local host found for non-MX address\n");
1371 return HOST_FOUND_LOCAL;
1374 HDEBUG(D_host_lookup)
1376 debug_printf("local host in host list - removed hosts:\n");
1377 for (h = prev->next; h != last->next; h = h->next)
1378 debug_printf(" %s %s %d\n", h->name, h->address, h->mx);
1381 if (removed != NULL) *removed = TRUE;
1382 prev->next = last->next;
1390 /*************************************************
1391 * Remove duplicate IPs in host list *
1392 *************************************************/
1394 /* You would think that administrators could set up their DNS records so that
1395 one ended up with a list of unique IP addresses after looking up A or MX
1396 records, but apparently duplication is common. So we scan such lists and
1397 remove the later duplicates. Note that we may get lists in which some host
1398 addresses are not set.
1401 host pointer to the first host in the chain
1402 lastptr pointer to pointer to the last host in the chain (may be updated)
1408 host_remove_duplicates(host_item *host, host_item **lastptr)
1410 while (host != *lastptr)
1412 if (host->address != NULL)
1414 host_item *h = host;
1415 while (h != *lastptr)
1417 if (h->next->address != NULL &&
1418 Ustrcmp(h->next->address, host->address) == 0)
1420 DEBUG(D_host_lookup) debug_printf("duplicate IP address %s (MX=%d) "
1421 "removed\n", host->address, h->next->mx);
1422 if (h->next == *lastptr) *lastptr = h;
1423 h->next = h->next->next;
1428 /* If the last item was removed, host may have become == *lastptr */
1429 if (host != *lastptr) host = host->next;
1436 /*************************************************
1437 * Find sender host name by gethostbyaddr() *
1438 *************************************************/
1440 /* This used to be the only way it was done, but it turns out that not all
1441 systems give aliases for calls to gethostbyaddr() - or one of the modern
1442 equivalents like getipnodebyaddr(). Fortunately, multiple PTR records are rare,
1443 but they can still exist. This function is now used only when a DNS lookup of
1444 the IP address fails, in order to give access to /etc/hosts.
1447 Returns: OK, DEFER, FAIL
1451 host_name_lookup_byaddr(void)
1455 struct hostent *hosts;
1456 struct in_addr addr;
1458 /* Lookup on IPv6 system */
1461 if (Ustrchr(sender_host_address, ':') != NULL)
1463 struct in6_addr addr6;
1464 if (inet_pton(AF_INET6, CS sender_host_address, &addr6) != 1)
1465 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "unable to parse \"%s\" as an "
1466 "IPv6 address", sender_host_address);
1467 #if HAVE_GETIPNODEBYADDR
1468 hosts = getipnodebyaddr(CS &addr6, sizeof(addr6), AF_INET6, &h_errno);
1470 hosts = gethostbyaddr(CS &addr6, sizeof(addr6), AF_INET6);
1475 if (inet_pton(AF_INET, CS sender_host_address, &addr) != 1)
1476 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "unable to parse \"%s\" as an "
1477 "IPv4 address", sender_host_address);
1478 #if HAVE_GETIPNODEBYADDR
1479 hosts = getipnodebyaddr(CS &addr, sizeof(addr), AF_INET, &h_errno);
1481 hosts = gethostbyaddr(CS &addr, sizeof(addr), AF_INET);
1485 /* Do lookup on IPv4 system */
1488 addr.s_addr = (S_ADDR_TYPE)inet_addr(CS sender_host_address);
1489 hosts = gethostbyaddr(CS(&addr), sizeof(addr), AF_INET);
1492 /* Failed to look up the host. */
1496 HDEBUG(D_host_lookup) debug_printf("IP address lookup failed: h_errno=%d\n",
1498 return (h_errno == TRY_AGAIN || h_errno == NO_RECOVERY) ? DEFER : FAIL;
1501 /* It seems there are some records in the DNS that yield an empty name. We
1502 treat this as non-existent. In some operating systems, this is returned as an
1503 empty string; in others as a single dot. */
1505 if (hosts->h_name == NULL || hosts->h_name[0] == 0 || hosts->h_name[0] == '.')
1507 HDEBUG(D_host_lookup) debug_printf("IP address lookup yielded an empty name: "
1508 "treated as non-existent host name\n");
1512 /* Copy and lowercase the name, which is in static storage in many systems.
1513 Put it in permanent memory. */
1515 s = (uschar *)hosts->h_name;
1516 len = Ustrlen(s) + 1;
1517 t = sender_host_name = store_get_perm(len);
1518 while (*s != 0) *t++ = tolower(*s++);
1521 /* If the host has aliases, build a copy of the alias list */
1523 if (hosts->h_aliases != NULL)
1526 uschar **aliases, **ptr;
1527 for (aliases = USS hosts->h_aliases; *aliases != NULL; aliases++) count++;
1528 ptr = sender_host_aliases = store_get_perm(count * sizeof(uschar *));
1529 for (aliases = USS hosts->h_aliases; *aliases != NULL; aliases++)
1531 uschar *s = *aliases;
1532 int len = Ustrlen(s) + 1;
1533 uschar *t = *ptr++ = store_get_perm(len);
1534 while (*s != 0) *t++ = tolower(*s++);
1545 /*************************************************
1546 * Find host name for incoming call *
1547 *************************************************/
1549 /* Put the name in permanent store, pointed to by sender_host_name. We also set
1550 up a list of alias names, pointed to by sender_host_alias. The list is
1551 NULL-terminated. The incoming address is in sender_host_address, either in
1552 dotted-quad form for IPv4 or in colon-separated form for IPv6.
1554 This function does a thorough check that the names it finds point back to the
1555 incoming IP address. Any that do not are discarded. Note that this is relied on
1556 by the ACL reverse_host_lookup check.
1558 On some systems, get{host,ipnode}byaddr() appears to do this internally, but
1559 this it not universally true. Also, for release 4.30, this function was changed
1560 to do a direct DNS lookup first, by default[1], because it turns out that that
1561 is the only guaranteed way to find all the aliases on some systems. My
1562 experiments indicate that Solaris gethostbyaddr() gives the aliases for but
1565 [1] The actual order is controlled by the host_lookup_order option.
1568 Returns: OK on success, the answer being placed in the global variable
1569 sender_host_name, with any aliases in a list hung off
1571 FAIL if no host name can be found
1572 DEFER if a temporary error was encountered
1574 The variable host_lookup_msg is set to an empty string on sucess, or to a
1575 reason for the failure otherwise, in a form suitable for tagging onto an error
1576 message, and also host_lookup_failed is set TRUE if the lookup failed. If there
1577 was a defer, host_lookup_deferred is set TRUE.
1579 Any dynamically constructed string for host_lookup_msg must be in permanent
1580 store, because it might be used for several incoming messages on the same SMTP
1584 host_name_lookup(void)
1588 uschar *hname, *save_hostname;
1592 const uschar *list = host_lookup_order;
1597 sender_host_dnssec = host_lookup_deferred = host_lookup_failed = FALSE;
1599 HDEBUG(D_host_lookup)
1600 debug_printf("looking up host name for %s\n", sender_host_address);
1602 /* For testing the case when a lookup does not complete, we have a special
1603 reserved IP address. */
1605 if (running_in_test_harness &&
1606 Ustrcmp(sender_host_address, "99.99.99.99") == 0)
1608 HDEBUG(D_host_lookup)
1609 debug_printf("Test harness: host name lookup returns DEFER\n");
1610 host_lookup_deferred = TRUE;
1614 /* Do lookups directly in the DNS or via gethostbyaddr() (or equivalent), in
1615 the order specified by the host_lookup_order option. */
1617 while ((ordername = string_nextinlist(&list, &sep, buffer, sizeof(buffer)))
1620 if (strcmpic(ordername, US"bydns") == 0)
1622 dns_init(FALSE, FALSE, FALSE); /* dnssec ctrl by dns_dnssec_ok glbl */
1623 dns_build_reverse(sender_host_address, buffer);
1624 rc = dns_lookup(&dnsa, buffer, T_PTR, NULL);
1626 /* The first record we come across is used for the name; others are
1627 considered to be aliases. We have to scan twice, in order to find out the
1628 number of aliases. However, if all the names are empty, we will behave as
1629 if failure. (PTR records that yield empty names have been encountered in
1632 if (rc == DNS_SUCCEED)
1634 uschar **aptr = NULL;
1637 int old_pool = store_pool;
1639 /* Ideally we'd check DNSSEC both forward and reverse, but we use the
1640 gethost* routines for forward, so can't do that unless/until we rewrite. */
1641 sender_host_dnssec = dns_is_secure(&dnsa);
1643 debug_printf("Reverse DNS security status: %s\n",
1644 sender_host_dnssec ? "DNSSEC verified (AD)" : "unverified");
1646 store_pool = POOL_PERM; /* Save names in permanent storage */
1648 for (rr = dns_next_rr(&dnsa, &dnss, RESET_ANSWERS);
1650 rr = dns_next_rr(&dnsa, &dnss, RESET_NEXT))
1652 if (rr->type == T_PTR) count++;
1655 /* Get store for the list of aliases. For compatibility with
1656 gethostbyaddr, we make an empty list if there are none. */
1658 aptr = sender_host_aliases = store_get(count * sizeof(uschar *));
1660 /* Re-scan and extract the names */
1662 for (rr = dns_next_rr(&dnsa, &dnss, RESET_ANSWERS);
1664 rr = dns_next_rr(&dnsa, &dnss, RESET_NEXT))
1667 if (rr->type != T_PTR) continue;
1668 s = store_get(ssize);
1670 /* If an overlong response was received, the data will have been
1671 truncated and dn_expand may fail. */
1673 if (dn_expand(dnsa.answer, dnsa.answer + dnsa.answerlen,
1674 (uschar *)(rr->data), (DN_EXPAND_ARG4_TYPE)(s), ssize) < 0)
1676 log_write(0, LOG_MAIN, "host name alias list truncated for %s",
1677 sender_host_address);
1681 store_reset(s + Ustrlen(s) + 1);
1684 HDEBUG(D_host_lookup) debug_printf("IP address lookup yielded an "
1685 "empty name: treated as non-existent host name\n");
1688 if (sender_host_name == NULL) sender_host_name = s;
1690 while (*s != 0) { *s = tolower(*s); s++; }
1693 *aptr = NULL; /* End of alias list */
1694 store_pool = old_pool; /* Reset store pool */
1696 /* If we've found a names, break out of the "order" loop */
1698 if (sender_host_name != NULL) break;
1701 /* If the DNS lookup deferred, we must also defer. */
1703 if (rc == DNS_AGAIN)
1705 HDEBUG(D_host_lookup)
1706 debug_printf("IP address PTR lookup gave temporary error\n");
1707 host_lookup_deferred = TRUE;
1712 /* Do a lookup using gethostbyaddr() - or equivalent */
1714 else if (strcmpic(ordername, US"byaddr") == 0)
1716 HDEBUG(D_host_lookup)
1717 debug_printf("IP address lookup using gethostbyaddr()\n");
1718 rc = host_name_lookup_byaddr();
1721 host_lookup_deferred = TRUE;
1722 return rc; /* Can't carry on */
1724 if (rc == OK) break; /* Found a name */
1726 } /* Loop for bydns/byaddr scanning */
1728 /* If we have failed to find a name, return FAIL and log when required.
1729 NB host_lookup_msg must be in permanent store. */
1731 if (sender_host_name == NULL)
1733 if (host_checking || !log_testing_mode)
1734 log_write(L_host_lookup_failed, LOG_MAIN, "no host name found for IP "
1735 "address %s", sender_host_address);
1736 host_lookup_msg = US" (failed to find host name from IP address)";
1737 host_lookup_failed = TRUE;
1741 HDEBUG(D_host_lookup)
1743 uschar **aliases = sender_host_aliases;
1744 debug_printf("IP address lookup yielded \"%s\"\n", sender_host_name);
1745 while (*aliases != NULL) debug_printf(" alias \"%s\"\n", *aliases++);
1748 /* We need to verify that a forward lookup on the name we found does indeed
1749 correspond to the address. This is for security: in principle a malefactor who
1750 happened to own a reverse zone could set it to point to any names at all.
1752 This code was present in versions of Exim before 3.20. At that point I took it
1753 out because I thought that gethostbyaddr() did the check anyway. It turns out
1754 that this isn't always the case, so it's coming back in at 4.01. This version
1755 is actually better, because it also checks aliases.
1757 The code was made more robust at release 4.21. Prior to that, it accepted all
1758 the names if any of them had the correct IP address. Now the code checks all
1759 the names, and accepts only those that have the correct IP address. */
1761 save_hostname = sender_host_name; /* Save for error messages */
1762 aliases = sender_host_aliases;
1763 for (hname = sender_host_name; hname != NULL; hname = *aliases++)
1773 /* When called with the last argument FALSE, host_find_byname() won't return
1774 HOST_FOUND_LOCAL. If the incoming address is an IPv4 address expressed in
1775 IPv6 format, we must compare the IPv4 part to any IPv4 addresses. */
1777 if ((rc = host_find_byname(&h, NULL, 0, NULL, FALSE)) == HOST_FOUND)
1780 HDEBUG(D_host_lookup) debug_printf("checking addresses for %s\n", hname);
1781 for (hh = &h; hh != NULL; hh = hh->next)
1783 if (host_is_in_net(hh->address, sender_host_address, 0))
1785 HDEBUG(D_host_lookup) debug_printf(" %s OK\n", hh->address);
1791 HDEBUG(D_host_lookup) debug_printf(" %s\n", hh->address);
1794 if (!ok) HDEBUG(D_host_lookup)
1795 debug_printf("no IP address for %s matched %s\n", hname,
1796 sender_host_address);
1798 else if (rc == HOST_FIND_AGAIN)
1800 HDEBUG(D_host_lookup) debug_printf("temporary error for host name lookup\n");
1801 host_lookup_deferred = TRUE;
1802 sender_host_name = NULL;
1807 HDEBUG(D_host_lookup) debug_printf("no IP addresses found for %s\n", hname);
1810 /* If this name is no good, and it's the sender name, set it null pro tem;
1811 if it's an alias, just remove it from the list. */
1815 if (hname == sender_host_name) sender_host_name = NULL; else
1817 uschar **a; /* Don't amalgamate - some */
1818 a = --aliases; /* compilers grumble */
1819 while (*a != NULL) { *a = a[1]; a++; }
1824 /* If sender_host_name == NULL, it means we didn't like the name. Replace
1825 it with the first alias, if there is one. */
1827 if (sender_host_name == NULL && *sender_host_aliases != NULL)
1828 sender_host_name = *sender_host_aliases++;
1830 /* If we now have a main name, all is well. */
1832 if (sender_host_name != NULL) return OK;
1834 /* We have failed to find an address that matches. */
1836 HDEBUG(D_host_lookup)
1837 debug_printf("%s does not match any IP address for %s\n",
1838 sender_host_address, save_hostname);
1840 /* This message must be in permanent store */
1842 old_pool = store_pool;
1843 store_pool = POOL_PERM;
1844 host_lookup_msg = string_sprintf(" (%s does not match any IP address for %s)",
1845 sender_host_address, save_hostname);
1846 store_pool = old_pool;
1847 host_lookup_failed = TRUE;
1854 /*************************************************
1855 * Find IP address(es) for host by name *
1856 *************************************************/
1858 /* The input is a host_item structure with the name filled in and the address
1859 field set to NULL. We use gethostbyname() or getipnodebyname() or
1860 gethostbyname2(), as appropriate. Of course, these functions may use the DNS,
1861 but they do not do MX processing. It appears, however, that in some systems the
1862 current setting of resolver options is used when one of these functions calls
1863 the resolver. For this reason, we call dns_init() at the start, with arguments
1864 influenced by bits in "flags", just as we do for host_find_bydns().
1866 The second argument provides a host list (usually an IP list) of hosts to
1867 ignore. This makes it possible to ignore IPv6 link-local addresses or loopback
1868 addresses in unreasonable places.
1870 The lookup may result in a change of name. For compatibility with the dns
1871 lookup, return this via fully_qualified_name as well as updating the host item.
1872 The lookup may also yield more than one IP address, in which case chain on
1873 subsequent host_item structures.
1876 host a host item with the name and MX filled in;
1877 the address is to be filled in;
1878 multiple IP addresses cause other host items to be
1880 ignore_target_hosts a list of hosts to ignore
1881 flags HOST_FIND_QUALIFY_SINGLE ) passed to
1882 HOST_FIND_SEARCH_PARENTS ) dns_init()
1883 fully_qualified_name if not NULL, set to point to host name for
1884 compatibility with host_find_bydns
1885 local_host_check TRUE if a check for the local host is wanted
1887 Returns: HOST_FIND_FAILED Failed to find the host or domain
1888 HOST_FIND_AGAIN Try again later
1889 HOST_FOUND Host found - data filled in
1890 HOST_FOUND_LOCAL Host found and is the local host
1894 host_find_byname(host_item *host, const uschar *ignore_target_hosts, int flags,
1895 const uschar **fully_qualified_name, BOOL local_host_check)
1897 int i, yield, times;
1899 host_item *last = NULL;
1900 BOOL temp_error = FALSE;
1905 /* If we are in the test harness, a name ending in .test.again.dns always
1906 forces a temporary error response, unless the name is in
1907 dns_again_means_nonexist. */
1909 if (running_in_test_harness)
1911 const uschar *endname = host->name + Ustrlen(host->name);
1912 if (Ustrcmp(endname - 14, "test.again.dns") == 0) goto RETURN_AGAIN;
1915 /* Make sure DNS options are set as required. This appears to be necessary in
1916 some circumstances when the get..byname() function actually calls the DNS. */
1918 dns_init((flags & HOST_FIND_QUALIFY_SINGLE) != 0,
1919 (flags & HOST_FIND_SEARCH_PARENTS) != 0,
1920 FALSE); /*XXX dnssec? */
1922 /* In an IPv6 world, unless IPv6 has been disabled, we need to scan for both
1923 kinds of address, so go round the loop twice. Note that we have ensured that
1924 AF_INET6 is defined even in an IPv4 world, which makes for slightly tidier
1925 code. However, if dns_ipv4_lookup matches the domain, we also just do IPv4
1926 lookups here (except when testing standalone). */
1933 (dns_ipv4_lookup != NULL &&
1934 match_isinlist(host->name, CUSS &dns_ipv4_lookup, 0, NULL, NULL,
1935 MCL_DOMAIN, TRUE, NULL) == OK))
1938 { af = AF_INET; times = 1; }
1940 { af = AF_INET6; times = 2; }
1942 /* No IPv6 support */
1944 #else /* HAVE_IPV6 */
1946 #endif /* HAVE_IPV6 */
1948 /* Initialize the flag that gets set for DNS syntax check errors, so that the
1949 interface to this function can be similar to host_find_bydns. */
1951 host_find_failed_syntax = FALSE;
1953 /* Loop to look up both kinds of address in an IPv6 world */
1955 for (i = 1; i <= times;
1957 af = AF_INET, /* If 2 passes, IPv4 on the second */
1963 struct hostent *hostdata;
1966 printf("Looking up: %s\n", host->name);
1970 if (running_in_test_harness)
1971 hostdata = host_fake_gethostbyname(host->name, af, &error_num);
1974 #if HAVE_GETIPNODEBYNAME
1975 hostdata = getipnodebyname(CS host->name, af, 0, &error_num);
1977 hostdata = gethostbyname2(CS host->name, af);
1978 error_num = h_errno;
1982 #else /* not HAVE_IPV6 */
1983 if (running_in_test_harness)
1984 hostdata = host_fake_gethostbyname(host->name, AF_INET, &error_num);
1987 hostdata = gethostbyname(CS host->name);
1988 error_num = h_errno;
1990 #endif /* HAVE_IPV6 */
1992 if (hostdata == NULL)
1997 case HOST_NOT_FOUND: error = US"HOST_NOT_FOUND"; break;
1998 case TRY_AGAIN: error = US"TRY_AGAIN"; break;
1999 case NO_RECOVERY: error = US"NO_RECOVERY"; break;
2000 case NO_DATA: error = US"NO_DATA"; break;
2001 #if NO_DATA != NO_ADDRESS
2002 case NO_ADDRESS: error = US"NO_ADDRESS"; break;
2004 default: error = US"?"; break;
2007 DEBUG(D_host_lookup) debug_printf("%s returned %d (%s)\n",
2009 #if HAVE_GETIPNODEBYNAME
2010 (af == AF_INET6)? "getipnodebyname(af=inet6)" : "getipnodebyname(af=inet)",
2012 (af == AF_INET6)? "gethostbyname2(af=inet6)" : "gethostbyname2(af=inet)",
2019 if (error_num == TRY_AGAIN || error_num == NO_RECOVERY) temp_error = TRUE;
2022 if ((hostdata->h_addr_list)[0] == NULL) continue;
2024 /* Replace the name with the fully qualified one if necessary, and fill in
2025 the fully_qualified_name pointer. */
2027 if (hostdata->h_name[0] != 0 &&
2028 Ustrcmp(host->name, hostdata->h_name) != 0)
2029 host->name = string_copy_dnsdomain((uschar *)hostdata->h_name);
2030 if (fully_qualified_name != NULL) *fully_qualified_name = host->name;
2032 /* Get the list of addresses. IPv4 and IPv6 addresses can be distinguished
2033 by their different lengths. Scan the list, ignoring any that are to be
2034 ignored, and build a chain from the rest. */
2036 ipv4_addr = hostdata->h_length == sizeof(struct in_addr);
2038 for (addrlist = USS hostdata->h_addr_list; *addrlist != NULL; addrlist++)
2040 uschar *text_address =
2041 host_ntoa(ipv4_addr? AF_INET:AF_INET6, *addrlist, NULL, NULL);
2044 if (ignore_target_hosts != NULL &&
2045 verify_check_this_host(&ignore_target_hosts, NULL, host->name,
2046 text_address, NULL) == OK)
2048 DEBUG(D_host_lookup)
2049 debug_printf("ignored host %s [%s]\n", host->name, text_address);
2054 /* If this is the first address, last == NULL and we put the data in the
2059 host->address = text_address;
2060 host->port = PORT_NONE;
2061 host->status = hstatus_unknown;
2062 host->why = hwhy_unknown;
2063 host->dnssec = DS_UNK;
2067 /* Else add further host item blocks for any other addresses, keeping
2072 host_item *next = store_get(sizeof(host_item));
2073 next->name = host->name;
2074 next->mx = host->mx;
2075 next->address = text_address;
2076 next->port = PORT_NONE;
2077 next->status = hstatus_unknown;
2078 next->why = hwhy_unknown;
2079 next->dnssec = DS_UNK;
2081 next->next = last->next;
2088 /* If no hosts were found, the address field in the original host block will be
2089 NULL. If temp_error is set, at least one of the lookups gave a temporary error,
2090 so we pass that back. */
2092 if (host->address == NULL)
2096 (message_id[0] == 0 && smtp_in != NULL)?
2097 string_sprintf("no IP address found for host %s (during %s)", host->name,
2098 smtp_get_connection_info()) :
2100 string_sprintf("no IP address found for host %s", host->name);
2102 HDEBUG(D_host_lookup) debug_printf("%s\n", msg);
2103 if (temp_error) goto RETURN_AGAIN;
2104 if (host_checking || !log_testing_mode)
2105 log_write(L_host_lookup_failed, LOG_MAIN, "%s", msg);
2106 return HOST_FIND_FAILED;
2109 /* Remove any duplicate IP addresses, then check to see if this is the local
2110 host if required. */
2112 host_remove_duplicates(host, &last);
2113 yield = local_host_check?
2114 host_scan_for_local_hosts(host, &last, NULL) : HOST_FOUND;
2116 HDEBUG(D_host_lookup)
2119 if (fully_qualified_name != NULL)
2120 debug_printf("fully qualified name = %s\n", *fully_qualified_name);
2121 debug_printf("%s looked up these IP addresses:\n",
2123 #if HAVE_GETIPNODEBYNAME
2132 for (h = host; h != last->next; h = h->next)
2133 debug_printf(" name=%s address=%s\n", h->name,
2134 (h->address == NULL)? US"<null>" : h->address);
2137 /* Return the found status. */
2141 /* Handle the case when there is a temporary error. If the name matches
2142 dns_again_means_nonexist, return permanent rather than temporary failure. */
2148 const uschar *save = deliver_domain;
2149 deliver_domain = host->name; /* set $domain */
2150 rc = match_isinlist(host->name, CUSS &dns_again_means_nonexist, 0, NULL, NULL,
2151 MCL_DOMAIN, TRUE, NULL);
2152 deliver_domain = save;
2155 DEBUG(D_host_lookup) debug_printf("%s is in dns_again_means_nonexist: "
2156 "returning HOST_FIND_FAILED\n", host->name);
2157 return HOST_FIND_FAILED;
2160 return HOST_FIND_AGAIN;
2166 /*************************************************
2167 * Fill in a host address from the DNS *
2168 *************************************************/
2170 /* Given a host item, with its name, port and mx fields set, and its address
2171 field set to NULL, fill in its IP address from the DNS. If it is multi-homed,
2172 create additional host items for the additional addresses, copying all the
2173 other fields, and randomizing the order.
2175 On IPv6 systems, A6 records are sought first (but only if support for A6 is
2176 configured - they may never become mainstream), then AAAA records are sought,
2177 and finally A records are sought as well.
2179 The host name may be changed if the DNS returns a different name - e.g. fully
2180 qualified or changed via CNAME. If fully_qualified_name is not NULL, dns_lookup
2181 ensures that it points to the fully qualified name. However, this is the fully
2182 qualified version of the original name; if a CNAME is involved, the actual
2183 canonical host name may be different again, and so we get it directly from the
2184 relevant RR. Note that we do NOT change the mx field of the host item in this
2185 function as it may be called to set the addresses of hosts taken from MX
2189 host points to the host item we're filling in
2190 lastptr points to pointer to last host item in a chain of
2191 host items (may be updated if host is last and gets
2192 extended because multihomed)
2193 ignore_target_hosts list of hosts to ignore
2194 allow_ip if TRUE, recognize an IP address and return it
2195 fully_qualified_name if not NULL, return fully qualified name here if
2196 the contents are different (i.e. it must be preset
2198 dnnssec_require if TRUE check the DNS result AD bit
2200 Returns: HOST_FIND_FAILED couldn't find A record
2201 HOST_FIND_AGAIN try again later
2202 HOST_FOUND found AAAA and/or A record(s)
2203 HOST_IGNORED found, but all IPs ignored
2207 set_address_from_dns(host_item *host, host_item **lastptr,
2208 const uschar *ignore_target_hosts, BOOL allow_ip,
2209 const uschar **fully_qualified_name,
2210 BOOL dnssec_request, BOOL dnssec_require)
2213 host_item *thishostlast = NULL; /* Indicates not yet filled in anything */
2214 BOOL v6_find_again = FALSE;
2217 /* If allow_ip is set, a name which is an IP address returns that value
2218 as its address. This is used for MX records when allow_mx_to_ip is set, for
2219 those sites that feel they have to flaunt the RFC rules. */
2221 if (allow_ip && string_is_ip_address(host->name, NULL) != 0)
2224 if (ignore_target_hosts != NULL &&
2225 verify_check_this_host(&ignore_target_hosts, NULL, host->name,
2226 host->name, NULL) == OK)
2227 return HOST_IGNORED;
2230 host->address = host->name;
2234 /* On an IPv6 system, unless IPv6 is disabled, go round the loop up to three
2235 times, looking for A6 and AAAA records the first two times. However, unless
2236 doing standalone testing, we force an IPv4 lookup if the domain matches
2237 dns_ipv4_lookup is set. Since A6 records look like being abandoned, support
2238 them only if explicitly configured to do so. On an IPv4 system, go round the
2239 loop once only, looking only for A records. */
2243 if (disable_ipv6 || (dns_ipv4_lookup != NULL &&
2244 match_isinlist(host->name, CUSS &dns_ipv4_lookup, 0, NULL, NULL,
2245 MCL_DOMAIN, TRUE, NULL) == OK))
2246 i = 0; /* look up A records only */
2248 #endif /* STAND_ALONE */
2251 i = 2; /* look up A6 and AAAA and A records */
2253 i = 1; /* look up AAAA and A records */
2254 #endif /* SUPPORT_A6 */
2256 /* The IPv4 world */
2258 #else /* HAVE_IPV6 */
2259 i = 0; /* look up A records only */
2260 #endif /* HAVE_IPV6 */
2264 static int types[] = { T_A, T_AAAA, T_A6 };
2265 int type = types[i];
2266 int randoffset = (i == 0)? 500 : 0; /* Ensures v6 sorts before v4 */
2270 int rc = dns_lookup(&dnsa, host->name, type, fully_qualified_name);
2271 lookup_dnssec_authenticated = !dnssec_request ? NULL
2272 : dns_is_secure(&dnsa) ? US"yes" : US"no";
2274 /* We want to return HOST_FIND_AGAIN if one of the A, A6, or AAAA lookups
2275 fails or times out, but not if another one succeeds. (In the early
2276 IPv6 days there are name servers that always fail on AAAA, but are happy
2277 to give out an A record. We want to proceed with that A record.) */
2279 if (rc != DNS_SUCCEED)
2281 if (i == 0) /* Just tried for an A record, i.e. end of loop */
2283 if (host->address != NULL) return HOST_FOUND; /* A6 or AAAA was found */
2284 if (rc == DNS_AGAIN || rc == DNS_FAIL || v6_find_again)
2285 return HOST_FIND_AGAIN;
2286 return HOST_FIND_FAILED; /* DNS_NOMATCH or DNS_NODATA */
2289 /* Tried for an A6 or AAAA record: remember if this was a temporary
2290 error, and look for the next record type. */
2292 if (rc != DNS_NOMATCH && rc != DNS_NODATA) v6_find_again = TRUE;
2298 if (dns_is_secure(&dnsa))
2300 DEBUG(D_host_lookup) debug_printf("%s A DNSSEC\n", host->name);
2301 if (host->dnssec == DS_UNK) /* set in host_find_bydns() */
2302 host->dnssec = DS_YES;
2308 log_write(L_host_lookup_failed, LOG_MAIN,
2309 "dnssec fail on %s for %.256s",
2310 i>1 ? "A6" : i>0 ? "AAAA" : "A", host->name);
2313 if (host->dnssec == DS_YES) /* set in host_find_bydns() */
2315 DEBUG(D_host_lookup) debug_printf("%s A cancel DNSSEC\n", host->name);
2316 host->dnssec = DS_NO;
2317 lookup_dnssec_authenticated = US"no";
2322 /* Lookup succeeded: fill in the given host item with the first non-ignored
2323 address found; create additional items for any others. A single A6 record
2324 may generate more than one address. */
2326 for (rr = dns_next_rr(&dnsa, &dnss, RESET_ANSWERS);
2328 rr = dns_next_rr(&dnsa, &dnss, RESET_NEXT))
2330 if (rr->type == type)
2332 /* dns_address *da = dns_address_from_rr(&dnsa, rr); */
2335 da = dns_address_from_rr(&dnsa, rr);
2337 DEBUG(D_host_lookup)
2340 debug_printf("no addresses extracted from A6 RR for %s\n",
2344 /* This loop runs only once for A and AAAA records, but may run
2345 several times for an A6 record that generated multiple addresses. */
2347 for (; da != NULL; da = da->next)
2350 if (ignore_target_hosts != NULL &&
2351 verify_check_this_host(&ignore_target_hosts, NULL,
2352 host->name, da->address, NULL) == OK)
2354 DEBUG(D_host_lookup)
2355 debug_printf("ignored host %s [%s]\n", host->name, da->address);
2360 /* If this is the first address, stick it in the given host block,
2361 and change the name if the returned RR has a different name. */
2363 if (thishostlast == NULL)
2365 if (strcmpic(host->name, rr->name) != 0)
2366 host->name = string_copy_dnsdomain(rr->name);
2367 host->address = da->address;
2368 host->sort_key = host->mx * 1000 + random_number(500) + randoffset;
2369 host->status = hstatus_unknown;
2370 host->why = hwhy_unknown;
2371 thishostlast = host;
2374 /* Not the first address. Check for, and ignore, duplicates. Then
2375 insert in the chain at a random point. */
2382 /* End of our local chain is specified by "thishostlast". */
2384 for (next = host;; next = next->next)
2386 if (Ustrcmp(CS da->address, next->address) == 0) break;
2387 if (next == thishostlast) { next = NULL; break; }
2389 if (next != NULL) continue; /* With loop for next address */
2391 /* Not a duplicate */
2393 new_sort_key = host->mx * 1000 + random_number(500) + randoffset;
2394 next = store_get(sizeof(host_item));
2396 /* New address goes first: insert the new block after the first one
2397 (so as not to disturb the original pointer) but put the new address
2398 in the original block. */
2400 if (new_sort_key < host->sort_key)
2402 *next = *host; /* Copies port */
2404 host->address = da->address;
2405 host->sort_key = new_sort_key;
2406 if (thishostlast == host) thishostlast = next; /* Local last */
2407 if (*lastptr == host) *lastptr = next; /* Global last */
2410 /* Otherwise scan down the addresses for this host to find the
2411 one to insert after. */
2415 host_item *h = host;
2416 while (h != thishostlast)
2418 if (new_sort_key < h->next->sort_key) break;
2421 *next = *h; /* Copies port */
2423 next->address = da->address;
2424 next->sort_key = new_sort_key;
2425 if (h == thishostlast) thishostlast = next; /* Local last */
2426 if (h == *lastptr) *lastptr = next; /* Global last */
2434 /* Control gets here only if the third lookup (the A record) succeeded.
2435 However, the address may not be filled in if it was ignored. */
2437 return (host->address == NULL)? HOST_IGNORED : HOST_FOUND;
2443 /*************************************************
2444 * Find IP addresses and host names via DNS *
2445 *************************************************/
2447 /* The input is a host_item structure with the name field filled in and the
2448 address field set to NULL. This may be in a chain of other host items. The
2449 lookup may result in more than one IP address, in which case we must created
2450 new host blocks for the additional addresses, and insert them into the chain.
2451 The original name may not be fully qualified. Use the fully_qualified_name
2452 argument to return the official name, as returned by the resolver.
2455 host point to initial host item
2456 ignore_target_hosts a list of hosts to ignore
2457 whichrrs flags indicating which RRs to look for:
2458 HOST_FIND_BY_SRV => look for SRV
2459 HOST_FIND_BY_MX => look for MX
2460 HOST_FIND_BY_A => look for A or AAAA
2461 also flags indicating how the lookup is done
2462 HOST_FIND_QUALIFY_SINGLE ) passed to the
2463 HOST_FIND_SEARCH_PARENTS ) resolver
2464 srv_service when SRV used, the service name
2465 srv_fail_domains DNS errors for these domains => assume nonexist
2466 mx_fail_domains DNS errors for these domains => assume nonexist
2467 dnssec_request_domains => make dnssec request
2468 dnssec_require_domains => ditto and nonexist failures
2469 fully_qualified_name if not NULL, return fully-qualified name
2470 removed set TRUE if local host was removed from the list
2472 Returns: HOST_FIND_FAILED Failed to find the host or domain;
2473 if there was a syntax error,
2474 host_find_failed_syntax is set.
2475 HOST_FIND_AGAIN Could not resolve at this time
2476 HOST_FOUND Host found
2477 HOST_FOUND_LOCAL The lowest MX record points to this
2478 machine, if MX records were found, or
2479 an A record that was found contains
2480 an address of the local host
2484 host_find_bydns(host_item *host, const uschar *ignore_target_hosts, int whichrrs,
2485 uschar *srv_service, uschar *srv_fail_domains, uschar *mx_fail_domains,
2486 uschar *dnssec_request_domains, uschar *dnssec_require_domains,
2487 const uschar **fully_qualified_name, BOOL *removed)
2489 host_item *h, *last;
2496 BOOL dnssec_require = match_isinlist(host->name, CUSS &dnssec_require_domains,
2497 0, NULL, NULL, MCL_DOMAIN, TRUE, NULL) == OK;
2498 BOOL dnssec_request = dnssec_require
2499 || match_isinlist(host->name, CUSS &dnssec_request_domains,
2500 0, NULL, NULL, MCL_DOMAIN, TRUE, NULL) == OK;
2501 dnssec_status_t dnssec;
2503 /* Set the default fully qualified name to the incoming name, initialize the
2504 resolver if necessary, set up the relevant options, and initialize the flag
2505 that gets set for DNS syntax check errors. */
2507 if (fully_qualified_name != NULL) *fully_qualified_name = host->name;
2508 dns_init((whichrrs & HOST_FIND_QUALIFY_SINGLE) != 0,
2509 (whichrrs & HOST_FIND_SEARCH_PARENTS) != 0,
2512 host_find_failed_syntax = FALSE;
2514 /* First, if requested, look for SRV records. The service name is given; we
2515 assume TCP progocol. DNS domain names are constrained to a maximum of 256
2516 characters, so the code below should be safe. */
2518 if ((whichrrs & HOST_FIND_BY_SRV) != 0)
2521 uschar *temp_fully_qualified_name = buffer;
2524 (void)sprintf(CS buffer, "_%s._tcp.%n%.256s", srv_service, &prefix_length,
2528 /* Search for SRV records. If the fully qualified name is different to
2529 the input name, pass back the new original domain, without the prepended
2533 lookup_dnssec_authenticated = NULL;
2534 rc = dns_lookup(&dnsa, buffer, ind_type, CUSS &temp_fully_qualified_name);
2538 if (dns_is_secure(&dnsa))
2539 { dnssec = DS_YES; lookup_dnssec_authenticated = US"yes"; }
2541 { dnssec = DS_NO; lookup_dnssec_authenticated = US"no"; }
2544 if (temp_fully_qualified_name != buffer && fully_qualified_name != NULL)
2545 *fully_qualified_name = temp_fully_qualified_name + prefix_length;
2547 /* On DNS failures, we give the "try again" error unless the domain is
2548 listed as one for which we continue. */
2550 if (rc == DNS_SUCCEED && dnssec_require && !dns_is_secure(&dnsa))
2552 log_write(L_host_lookup_failed, LOG_MAIN,
2553 "dnssec fail on SRV for %.256s", host->name);
2556 if (rc == DNS_FAIL || rc == DNS_AGAIN)
2559 if (match_isinlist(host->name, CUSS &srv_fail_domains, 0, NULL, NULL,
2560 MCL_DOMAIN, TRUE, NULL) != OK)
2562 { yield = HOST_FIND_AGAIN; goto out; }
2563 DEBUG(D_host_lookup) debug_printf("DNS_%s treated as DNS_NODATA "
2564 "(domain in srv_fail_domains)\n", (rc == DNS_FAIL)? "FAIL":"AGAIN");
2568 /* If we did not find any SRV records, search the DNS for MX records, if
2569 requested to do so. If the result is DNS_NOMATCH, it means there is no such
2570 domain, and there's no point in going on to look for address records with the
2571 same domain. The result will be DNS_NODATA if the domain exists but has no MX
2572 records. On DNS failures, we give the "try again" error unless the domain is
2573 listed as one for which we continue. */
2575 if (rc != DNS_SUCCEED && (whichrrs & HOST_FIND_BY_MX) != 0)
2579 lookup_dnssec_authenticated = NULL;
2580 rc = dns_lookup(&dnsa, host->name, ind_type, fully_qualified_name);
2584 if (dns_is_secure(&dnsa))
2586 DEBUG(D_host_lookup) debug_printf("%s MX DNSSEC\n", host->name);
2587 dnssec = DS_YES; lookup_dnssec_authenticated = US"yes";
2591 dnssec = DS_NO; lookup_dnssec_authenticated = US"no";
2598 yield = HOST_FIND_FAILED; goto out;
2601 if (!dnssec_require || dns_is_secure(&dnsa))
2603 log_write(L_host_lookup_failed, LOG_MAIN,
2604 "dnssec fail on MX for %.256s", host->name);
2611 if (match_isinlist(host->name, CUSS &mx_fail_domains, 0, NULL, NULL,
2612 MCL_DOMAIN, TRUE, NULL) != OK)
2614 { yield = HOST_FIND_AGAIN; goto out; }
2615 DEBUG(D_host_lookup) debug_printf("DNS_%s treated as DNS_NODATA "
2616 "(domain in mx_fail_domains)\n", (rc == DNS_FAIL)? "FAIL":"AGAIN");
2621 /* If we haven't found anything yet, and we are requested to do so, try for an
2622 A or AAAA record. If we find it (or them) check to see that it isn't the local
2625 if (rc != DNS_SUCCEED)
2627 if ((whichrrs & HOST_FIND_BY_A) == 0)
2629 DEBUG(D_host_lookup) debug_printf("Address records are not being sought\n");
2630 yield = HOST_FIND_FAILED;
2634 last = host; /* End of local chainlet */
2636 host->port = PORT_NONE;
2637 host->dnssec = DS_UNK;
2638 lookup_dnssec_authenticated = NULL;
2639 rc = set_address_from_dns(host, &last, ignore_target_hosts, FALSE,
2640 fully_qualified_name, dnssec_request, dnssec_require);
2642 /* If one or more address records have been found, check that none of them
2643 are local. Since we know the host items all have their IP addresses
2644 inserted, host_scan_for_local_hosts() can only return HOST_FOUND or
2645 HOST_FOUND_LOCAL. We do not need to scan for duplicate IP addresses here,
2646 because set_address_from_dns() removes them. */
2648 if (rc == HOST_FOUND)
2649 rc = host_scan_for_local_hosts(host, &last, removed);
2651 if (rc == HOST_IGNORED) rc = HOST_FIND_FAILED; /* No special action */
2653 DEBUG(D_host_lookup)
2656 if (host->address != NULL)
2658 if (fully_qualified_name != NULL)
2659 debug_printf("fully qualified name = %s\n", *fully_qualified_name);
2660 for (h = host; h != last->next; h = h->next)
2661 debug_printf("%s %s mx=%d sort=%d %s\n", h->name,
2662 (h->address == NULL)? US"<null>" : h->address, h->mx, h->sort_key,
2663 (h->status >= hstatus_unusable)? US"*" : US"");
2671 /* We have found one or more MX or SRV records. Sort them according to
2672 precedence. Put the data for the first one into the existing host block, and
2673 insert new host_item blocks into the chain for the remainder. For equal
2674 precedences one is supposed to randomize the order. To make this happen, the
2675 sorting is actually done on the MX value * 1000 + a random number. This is put
2676 into a host field called sort_key.
2678 In the case of hosts with both IPv6 and IPv4 addresses, we want to choose the
2679 IPv6 address in preference. At this stage, we don't know what kind of address
2680 the host has. We choose a random number < 500; if later we find an A record
2681 first, we add 500 to the random number. Then for any other address records, we
2682 use random numbers in the range 0-499 for AAAA records and 500-999 for A
2685 At this point we remove any duplicates that point to the same host, retaining
2686 only the one with the lowest precedence. We cannot yet check for precedence
2687 greater than that of the local host, because that test cannot be properly done
2688 until the addresses have been found - an MX record may point to a name for this
2689 host which is not the primary hostname. */
2691 last = NULL; /* Indicates that not even the first item is filled yet */
2693 for (rr = dns_next_rr(&dnsa, &dnss, RESET_ANSWERS);
2695 rr = dns_next_rr(&dnsa, &dnss, RESET_NEXT))
2698 int weight = 0; /* For SRV records */
2699 int port = PORT_NONE;
2700 uschar *s; /* MUST be unsigned for GETSHORT */
2703 if (rr->type != ind_type) continue;
2705 GETSHORT(precedence, s); /* Pointer s is advanced */
2707 /* For MX records, we use a random "weight" which causes multiple records of
2708 the same precedence to sort randomly. */
2710 if (ind_type == T_MX)
2711 weight = random_number(500);
2713 /* SRV records are specified with a port and a weight. The weight is used
2714 in a special algorithm. However, to start with, we just use it to order the
2715 records of equal priority (precedence). */
2719 GETSHORT(weight, s);
2723 /* Get the name of the host pointed to. */
2725 (void)dn_expand(dnsa.answer, dnsa.answer + dnsa.answerlen, s,
2726 (DN_EXPAND_ARG4_TYPE)data, sizeof(data));
2728 /* Check that we haven't already got this host on the chain; if we have,
2729 keep only the lower precedence. This situation shouldn't occur, but you
2730 never know what junk might get into the DNS (and this case has been seen on
2731 more than one occasion). */
2733 if (last != NULL) /* This is not the first record */
2735 host_item *prev = NULL;
2737 for (h = host; h != last->next; prev = h, h = h->next)
2739 if (strcmpic(h->name, data) == 0)
2741 DEBUG(D_host_lookup)
2742 debug_printf("discarded duplicate host %s (MX=%d)\n", data,
2743 (precedence > h->mx)? precedence : h->mx);
2744 if (precedence >= h->mx) goto NEXT_MX_RR; /* Skip greater precedence */
2745 if (h == host) /* Override first item */
2748 host->sort_key = precedence * 1000 + weight;
2752 /* Unwanted host item is not the first in the chain, so we can get
2753 get rid of it by cutting it out. */
2755 prev->next = h->next;
2756 if (h == last) last = prev;
2762 /* If this is the first MX or SRV record, put the data into the existing host
2763 block. Otherwise, add a new block in the correct place; if it has to be
2764 before the first block, copy the first block's data to a new second block. */
2768 host->name = string_copy_dnsdomain(data);
2769 host->address = NULL;
2771 host->mx = precedence;
2772 host->sort_key = precedence * 1000 + weight;
2773 host->status = hstatus_unknown;
2774 host->why = hwhy_unknown;
2775 host->dnssec = dnssec;
2779 /* Make a new host item and seek the correct insertion place */
2783 int sort_key = precedence * 1000 + weight;
2784 host_item *next = store_get(sizeof(host_item));
2785 next->name = string_copy_dnsdomain(data);
2786 next->address = NULL;
2788 next->mx = precedence;
2789 next->sort_key = sort_key;
2790 next->status = hstatus_unknown;
2791 next->why = hwhy_unknown;
2792 next->dnssec = dnssec;
2795 /* Handle the case when we have to insert before the first item. */
2797 if (sort_key < host->sort_key)
2804 if (last == host) last = next;
2807 /* Else scan down the items we have inserted as part of this exercise;
2808 don't go further. */
2812 for (h = host; h != last; h = h->next)
2814 if (sort_key < h->next->sort_key)
2816 next->next = h->next;
2822 /* Join on after the last host item that's part of this
2823 processing if we haven't stopped sooner. */
2827 next->next = last->next;
2834 NEXT_MX_RR: continue;
2837 /* If the list of hosts was obtained from SRV records, there are two things to
2838 do. First, if there is only one host, and it's name is ".", it means there is
2839 no SMTP service at this domain. Otherwise, we have to sort the hosts of equal
2840 priority according to their weights, using an algorithm that is defined in RFC
2841 2782. The hosts are currently sorted by priority and weight. For each priority
2842 group we have to pick off one host and put it first, and then repeat for any
2843 remaining in the same priority group. */
2845 if (ind_type == T_SRV)
2849 if (host == last && host->name[0] == 0)
2851 DEBUG(D_host_lookup) debug_printf("the single SRV record is \".\"\n");
2852 yield = HOST_FIND_FAILED;
2856 DEBUG(D_host_lookup)
2858 debug_printf("original ordering of hosts from SRV records:\n");
2859 for (h = host; h != last->next; h = h->next)
2860 debug_printf(" %s P=%d W=%d\n", h->name, h->mx, h->sort_key % 1000);
2863 for (pptr = &host, h = host; h != last; pptr = &(h->next), h = h->next)
2868 /* Find the last following host that has the same precedence. At the same
2869 time, compute the sum of the weights and the running totals. These can be
2870 stored in the sort_key field. */
2872 for (hh = h; hh != last; hh = hh->next)
2874 int weight = hh->sort_key % 1000; /* was precedence * 1000 + weight */
2877 if (hh->mx != hh->next->mx) break;
2880 /* If there's more than one host at this precedence (priority), we need to
2881 pick one to go first. */
2887 int randomizer = random_number(sum + 1);
2889 for (ppptr = pptr, hhh = h;
2891 ppptr = &(hhh->next), hhh = hhh->next)
2893 if (hhh->sort_key >= randomizer) break;
2896 /* hhh now points to the host that should go first; ppptr points to the
2897 place that points to it. Unfortunately, if the start of the minilist is
2898 the start of the entire list, we can't just swap the items over, because
2899 we must not change the value of host, since it is passed in from outside.
2900 One day, this could perhaps be changed.
2902 The special case is fudged by putting the new item *second* in the chain,
2903 and then transferring the data between the first and second items. We
2904 can't just swap the first and the chosen item, because that would mean
2905 that an item with zero weight might no longer be first. */
2909 *ppptr = hhh->next; /* Cuts it out of the chain */
2913 host_item temp = *h;
2916 hhh->next = temp.next;
2922 hhh->next = h; /* The rest of the chain follows it */
2923 *pptr = hhh; /* It takes the place of h */
2924 h = hhh; /* It's now the start of this minilist */
2929 /* A host has been chosen to be first at this priority and h now points
2930 to this host. There may be others at the same priority, or others at a
2931 different priority. Before we leave this host, we need to put back a sort
2932 key of the traditional MX kind, in case this host is multihomed, because
2933 the sort key is used for ordering the multiple IP addresses. We do not need
2934 to ensure that these new sort keys actually reflect the order of the hosts,
2937 h->sort_key = h->mx * 1000 + random_number(500);
2938 } /* Move on to the next host */
2941 /* Now we have to find IP addresses for all the hosts. We have ensured above
2942 that the names in all the host items are unique. Before release 4.61 we used to
2943 process records from the additional section in the DNS packet that returned the
2944 MX or SRV records. However, a DNS name server is free to drop any resource
2945 records from the additional section. In theory, this has always been a
2946 potential problem, but it is exacerbated by the advent of IPv6. If a host had
2947 several IPv4 addresses and some were not in the additional section, at least
2948 Exim would try the others. However, if a host had both IPv4 and IPv6 addresses
2949 and all the IPv4 (say) addresses were absent, Exim would try only for a IPv6
2950 connection, and never try an IPv4 address. When there was only IPv4
2951 connectivity, this was a disaster that did in practice occur.
2953 So, from release 4.61 onwards, we always search for A and AAAA records
2954 explicitly. The names shouldn't point to CNAMES, but we use the general lookup
2955 function that handles them, just in case. If any lookup gives a soft error,
2956 change the default yield.
2958 For these DNS lookups, we must disable qualify_single and search_parents;
2959 otherwise invalid host names obtained from MX or SRV records can cause trouble
2960 if they happen to match something local. */
2962 yield = HOST_FIND_FAILED; /* Default yield */
2963 dns_init(FALSE, FALSE, /* Disable qualify_single and search_parents */
2964 dnssec_request || dnssec_require);
2966 for (h = host; h != last->next; h = h->next)
2968 if (h->address != NULL) continue; /* Inserted by a multihomed host */
2969 rc = set_address_from_dns(h, &last, ignore_target_hosts, allow_mx_to_ip,
2970 NULL, dnssec_request, dnssec_require);
2971 if (rc != HOST_FOUND)
2973 h->status = hstatus_unusable;
2974 if (rc == HOST_FIND_AGAIN)
2977 h->why = hwhy_deferred;
2980 h->why = (rc == HOST_IGNORED)? hwhy_ignored : hwhy_failed;
2984 /* Scan the list for any hosts that are marked unusable because they have
2985 been explicitly ignored, and remove them from the list, as if they did not
2986 exist. If we end up with just a single, ignored host, flatten its fields as if
2987 nothing was found. */
2989 if (ignore_target_hosts != NULL)
2991 host_item *prev = NULL;
2992 for (h = host; h != last->next; h = h->next)
2995 if (h->why != hwhy_ignored) /* Non ignored host, just continue */
2997 else if (prev == NULL) /* First host is ignored */
2999 if (h != last) /* First is not last */
3001 if (h->next == last) last = h; /* Overwrite it with next */
3002 *h = *(h->next); /* and reprocess it. */
3003 goto REDO; /* C should have redo, like Perl */
3006 else /* Ignored host is not first - */
3008 prev->next = h->next;
3009 if (h == last) last = prev;
3013 if (host->why == hwhy_ignored) host->address = NULL;
3016 /* There is still one complication in the case of IPv6. Although the code above
3017 arranges that IPv6 addresses take precedence over IPv4 addresses for multihomed
3018 hosts, it doesn't do this for addresses that apply to different hosts with the
3019 same MX precedence, because the sorting on MX precedence happens first. So we
3020 have to make another pass to check for this case. We ensure that, within a
3021 single MX preference value, IPv6 addresses come first. This can separate the
3022 addresses of a multihomed host, but that should not matter. */
3025 if (h != last && !disable_ipv6)
3027 for (h = host; h != last; h = h->next)
3030 host_item *next = h->next;
3031 if (h->mx != next->mx || /* If next is different MX */
3032 h->address == NULL || /* OR this one is unset */
3033 Ustrchr(h->address, ':') != NULL || /* OR this one is IPv6 */
3034 (next->address != NULL &&
3035 Ustrchr(next->address, ':') == NULL)) /* OR next is IPv4 */
3036 continue; /* move on to next */
3037 temp = *h; /* otherwise, swap */
3038 temp.next = next->next;
3046 /* Remove any duplicate IP addresses and then scan the list of hosts for any
3047 whose IP addresses are on the local host. If any are found, all hosts with the
3048 same or higher MX values are removed. However, if the local host has the lowest
3049 numbered MX, then HOST_FOUND_LOCAL is returned. Otherwise, if at least one host
3050 with an IP address is on the list, HOST_FOUND is returned. Otherwise,
3051 HOST_FIND_FAILED is returned, but in this case do not update the yield, as it
3052 might have been set to HOST_FIND_AGAIN just above here. If not, it will already
3053 be HOST_FIND_FAILED. */
3055 host_remove_duplicates(host, &last);
3056 rc = host_scan_for_local_hosts(host, &last, removed);
3057 if (rc != HOST_FIND_FAILED) yield = rc;
3059 DEBUG(D_host_lookup)
3061 if (fully_qualified_name != NULL)
3062 debug_printf("fully qualified name = %s\n", *fully_qualified_name);
3063 debug_printf("host_find_bydns yield = %s (%d); returned hosts:\n",
3064 (yield == HOST_FOUND)? "HOST_FOUND" :
3065 (yield == HOST_FOUND_LOCAL)? "HOST_FOUND_LOCAL" :
3066 (yield == HOST_FIND_AGAIN)? "HOST_FIND_AGAIN" :
3067 (yield == HOST_FIND_FAILED)? "HOST_FIND_FAILED" : "?",
3069 for (h = host; h != last->next; h = h->next)
3071 debug_printf(" %s %s MX=%d %s", h->name,
3072 !h->address ? US"<null>" : h->address, h->mx,
3073 h->dnssec == DS_YES ? US"DNSSEC " : US"");
3074 if (h->port != PORT_NONE) debug_printf("port=%d ", h->port);
3075 if (h->status >= hstatus_unusable) debug_printf("*");
3082 dns_init(FALSE, FALSE, FALSE); /* clear the dnssec bit for getaddrbyname */
3089 /*************************************************
3090 **************************************************
3091 * Stand-alone test program *
3092 **************************************************
3093 *************************************************/
3097 int main(int argc, char **cargv)
3100 int whichrrs = HOST_FIND_BY_MX | HOST_FIND_BY_A;
3101 BOOL byname = FALSE;
3102 BOOL qualify_single = TRUE;
3103 BOOL search_parents = FALSE;
3104 BOOL request_dnssec = FALSE;
3105 BOOL require_dnssec = FALSE;
3106 uschar **argv = USS cargv;
3109 disable_ipv6 = FALSE;
3110 primary_hostname = US"";
3111 store_pool = POOL_MAIN;
3112 debug_selector = D_host_lookup|D_interface;
3113 debug_file = stdout;
3114 debug_fd = fileno(debug_file);
3116 printf("Exim stand-alone host functions test\n");
3118 host_find_interfaces();
3119 debug_selector = D_host_lookup | D_dns;
3121 if (argc > 1) primary_hostname = argv[1];
3123 /* So that debug level changes can be done first */
3125 dns_init(qualify_single, search_parents, FALSE);
3127 printf("Testing host lookup\n");
3129 while (Ufgets(buffer, 256, stdin) != NULL)
3132 int len = Ustrlen(buffer);
3133 uschar *fully_qualified_name;
3135 while (len > 0 && isspace(buffer[len-1])) len--;
3138 if (Ustrcmp(buffer, "q") == 0) break;
3140 if (Ustrcmp(buffer, "byname") == 0) byname = TRUE;
3141 else if (Ustrcmp(buffer, "no_byname") == 0) byname = FALSE;
3142 else if (Ustrcmp(buffer, "a_only") == 0) whichrrs = HOST_FIND_BY_A;
3143 else if (Ustrcmp(buffer, "mx_only") == 0) whichrrs = HOST_FIND_BY_MX;
3144 else if (Ustrcmp(buffer, "srv_only") == 0) whichrrs = HOST_FIND_BY_SRV;
3145 else if (Ustrcmp(buffer, "srv+a") == 0)
3146 whichrrs = HOST_FIND_BY_SRV | HOST_FIND_BY_A;
3147 else if (Ustrcmp(buffer, "srv+mx") == 0)
3148 whichrrs = HOST_FIND_BY_SRV | HOST_FIND_BY_MX;
3149 else if (Ustrcmp(buffer, "srv+mx+a") == 0)
3150 whichrrs = HOST_FIND_BY_SRV | HOST_FIND_BY_MX | HOST_FIND_BY_A;
3151 else if (Ustrcmp(buffer, "qualify_single") == 0) qualify_single = TRUE;
3152 else if (Ustrcmp(buffer, "no_qualify_single") == 0) qualify_single = FALSE;
3153 else if (Ustrcmp(buffer, "search_parents") == 0) search_parents = TRUE;
3154 else if (Ustrcmp(buffer, "no_search_parents") == 0) search_parents = FALSE;
3155 else if (Ustrcmp(buffer, "request_dnssec") == 0) request_dnssec = TRUE;
3156 else if (Ustrcmp(buffer, "no_request_dnssec") == 0) request_dnssec = FALSE;
3157 else if (Ustrcmp(buffer, "require_dnssec") == 0) require_dnssec = TRUE;
3158 else if (Ustrcmp(buffer, "no_reqiret_dnssec") == 0) require_dnssec = FALSE;
3159 else if (Ustrcmp(buffer, "test_harness") == 0)
3160 running_in_test_harness = !running_in_test_harness;
3161 else if (Ustrcmp(buffer, "ipv6") == 0) disable_ipv6 = !disable_ipv6;
3162 else if (Ustrcmp(buffer, "res_debug") == 0)
3164 _res.options ^= RES_DEBUG;
3166 else if (Ustrncmp(buffer, "retrans", 7) == 0)
3168 (void)sscanf(CS(buffer+8), "%d", &dns_retrans);
3169 _res.retrans = dns_retrans;
3171 else if (Ustrncmp(buffer, "retry", 5) == 0)
3173 (void)sscanf(CS(buffer+6), "%d", &dns_retry);
3174 _res.retry = dns_retry;
3178 int flags = whichrrs;
3184 h.status = hstatus_unknown;
3185 h.why = hwhy_unknown;
3188 if (qualify_single) flags |= HOST_FIND_QUALIFY_SINGLE;
3189 if (search_parents) flags |= HOST_FIND_SEARCH_PARENTS;
3192 ? host_find_byname(&h, NULL, flags, &fully_qualified_name, TRUE)
3193 : host_find_bydns(&h, NULL, flags, US"smtp", NULL, NULL,
3194 request_dnssec ? &h.name : NULL,
3195 require_dnssec ? &h.name : NULL,
3196 &fully_qualified_name, NULL);
3198 if (rc == HOST_FIND_FAILED) printf("Failed\n");
3199 else if (rc == HOST_FIND_AGAIN) printf("Again\n");
3200 else if (rc == HOST_FOUND_LOCAL) printf("Local\n");
3206 printf("Testing host_aton\n");
3208 while (Ufgets(buffer, 256, stdin) != NULL)
3212 int len = Ustrlen(buffer);
3214 while (len > 0 && isspace(buffer[len-1])) len--;
3217 if (Ustrcmp(buffer, "q") == 0) break;
3219 len = host_aton(buffer, x);
3220 printf("length = %d ", len);
3221 for (i = 0; i < len; i++)
3223 printf("%04x ", (x[i] >> 16) & 0xffff);
3224 printf("%04x ", x[i] & 0xffff);
3231 printf("Testing host_name_lookup\n");
3233 while (Ufgets(buffer, 256, stdin) != NULL)
3235 int len = Ustrlen(buffer);
3236 while (len > 0 && isspace(buffer[len-1])) len--;
3238 if (Ustrcmp(buffer, "q") == 0) break;
3239 sender_host_address = buffer;
3240 sender_host_name = NULL;
3241 sender_host_aliases = NULL;
3242 host_lookup_msg = US"";
3243 host_lookup_failed = FALSE;
3244 if (host_name_lookup() == FAIL) /* Debug causes printing */
3245 printf("Lookup failed:%s\n", host_lookup_msg);
3253 #endif /* STAND_ALONE */