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;
97 /*************************************************
98 * Wrappers for logging lookup times *
99 *************************************************/
101 /* When the 'slow_lookup_log' variable is enabled, these wrappers will
102 write to the log file all (potential) dns lookups that take more than
103 slow_lookup_log milliseconds
107 log_long_lookup(const uschar * type, const uschar * data, unsigned long msec)
109 log_write(0, LOG_MAIN, "Long %s lookup for '%s': %lu msec",
114 /* returns the current system epoch time in milliseconds. */
118 struct timeval tmp_time;
119 unsigned long seconds, microseconds;
121 gettimeofday(&tmp_time, NULL);
122 seconds = (unsigned long) tmp_time.tv_sec;
123 microseconds = (unsigned long) tmp_time.tv_usec;
124 return seconds*1000 + microseconds/1000;
129 dns_lookup_timerwrap(dns_answer *dnsa, const uschar *name, int type,
130 const uschar **fully_qualified_name)
133 unsigned long time_msec;
135 if (!slow_lookup_log)
136 return dns_lookup(dnsa, name, type, fully_qualified_name);
138 time_msec = get_time_in_ms();
139 retval = dns_lookup(dnsa, name, type, fully_qualified_name);
140 if ((time_msec = get_time_in_ms() - time_msec) > slow_lookup_log)
141 log_long_lookup(US"name", name, time_msec);
146 /*************************************************
147 * Replace gethostbyname() when testing *
148 *************************************************/
150 /* This function is called instead of gethostbyname(), gethostbyname2(), or
151 getipnodebyname() when running in the test harness. . It also
152 recognizes an unqualified "localhost" and forces it to the appropriate loopback
153 address. IP addresses are treated as literals. For other names, it uses the DNS
154 to find the host name. In the test harness, this means it will access only the
158 name the host name or a textual IP address
159 af AF_INET or AF_INET6
160 error_num where to put an error code:
161 HOST_NOT_FOUND/TRY_AGAIN/NO_RECOVERY/NO_DATA
163 Returns: a hostent structure or NULL for an error
166 static struct hostent *
167 host_fake_gethostbyname(const uschar *name, int af, int *error_num)
170 int alen = (af == AF_INET)? sizeof(struct in_addr):sizeof(struct in6_addr);
172 int alen = sizeof(struct in_addr);
176 const uschar *lname = name;
179 struct hostent *yield;
185 debug_printf("using host_fake_gethostbyname for %s (%s)\n", name,
186 (af == AF_INET)? "IPv4" : "IPv6");
188 /* Handle unqualified "localhost" */
190 if (Ustrcmp(name, "localhost") == 0)
191 lname = (af == AF_INET)? US"127.0.0.1" : US"::1";
193 /* Handle a literal IP address */
195 ipa = string_is_ip_address(lname, NULL);
198 if ((ipa == 4 && af == AF_INET) ||
199 (ipa == 6 && af == AF_INET6))
203 yield = store_get(sizeof(struct hostent));
204 alist = store_get(2 * sizeof(char *));
205 adds = store_get(alen);
206 yield->h_name = CS name;
207 yield->h_aliases = NULL;
208 yield->h_addrtype = af;
209 yield->h_length = alen;
210 yield->h_addr_list = CSS alist;
212 n = host_aton(lname, x);
213 for (i = 0; i < n; i++)
216 *adds++ = (y >> 24) & 255;
217 *adds++ = (y >> 16) & 255;
218 *adds++ = (y >> 8) & 255;
224 /* Wrong kind of literal address */
228 *error_num = HOST_NOT_FOUND;
233 /* Handle a host name */
237 int type = (af == AF_INET)? T_A:T_AAAA;
238 int rc = dns_lookup_timerwrap(&dnsa, lname, type, NULL);
241 lookup_dnssec_authenticated = NULL;
245 case DNS_SUCCEED: break;
246 case DNS_NOMATCH: *error_num = HOST_NOT_FOUND; return NULL;
247 case DNS_NODATA: *error_num = NO_DATA; return NULL;
248 case DNS_AGAIN: *error_num = TRY_AGAIN; return NULL;
250 case DNS_FAIL: *error_num = NO_RECOVERY; return NULL;
253 for (rr = dns_next_rr(&dnsa, &dnss, RESET_ANSWERS);
255 rr = dns_next_rr(&dnsa, &dnss, RESET_NEXT))
257 if (rr->type == type) count++;
260 yield = store_get(sizeof(struct hostent));
261 alist = store_get((count + 1) * sizeof(char **));
262 adds = store_get(count *alen);
264 yield->h_name = CS name;
265 yield->h_aliases = NULL;
266 yield->h_addrtype = af;
267 yield->h_length = alen;
268 yield->h_addr_list = CSS alist;
270 for (rr = dns_next_rr(&dnsa, &dnss, RESET_ANSWERS);
272 rr = dns_next_rr(&dnsa, &dnss, RESET_NEXT))
277 if (rr->type != type) continue;
278 da = dns_address_from_rr(&dnsa, rr);
280 n = host_aton(da->address, x);
281 for (i = 0; i < n; i++)
284 *adds++ = (y >> 24) & 255;
285 *adds++ = (y >> 16) & 255;
286 *adds++ = (y >> 8) & 255;
298 /*************************************************
299 * Build chain of host items from list *
300 *************************************************/
302 /* This function builds a chain of host items from a textual list of host
303 names. It does not do any lookups. If randomize is true, the chain is build in
304 a randomized order. There may be multiple groups of independently randomized
305 hosts; they are delimited by a host name consisting of just "+".
308 anchor anchor for the chain
310 randomize TRUE for randomizing
316 host_build_hostlist(host_item **anchor, const uschar *list, BOOL randomize)
319 int fake_mx = MX_NONE; /* This value is actually -1 */
322 if (list == NULL) return;
323 if (randomize) fake_mx--; /* Start at -2 for randomizing */
327 while ((name = string_nextinlist(&list, &sep, NULL, 0)) != NULL)
331 if (name[0] == '+' && name[1] == 0) /* "+" delimits a randomized group */
332 { /* ignore if not randomizing */
333 if (randomize) fake_mx--;
337 h = store_get(sizeof(host_item));
342 h->sort_key = randomize? (-fake_mx)*1000 + random_number(1000) : 0;
343 h->status = hstatus_unknown;
344 h->why = hwhy_unknown;
354 host_item *hh = *anchor;
355 if (h->sort_key < hh->sort_key)
362 while (hh->next != NULL && h->sort_key >= (hh->next)->sort_key)
375 /*************************************************
376 * Extract port from address string *
377 *************************************************/
379 /* In the spool file, and in the -oMa and -oMi options, a host plus port is
380 given as an IP address followed by a dot and a port number. This function
383 An alternative format for the -oMa and -oMi options is [ip address]:port which
384 is what Exim 4 uses for output, because it seems to becoming commonly used,
385 whereas the dot form confuses some programs/people. So we recognize that form
389 address points to the string; if there is a port, the '.' in the string
390 is overwritten with zero to terminate the address; if the string
391 is in the [xxx]:ppp format, the address is shifted left and the
394 Returns: 0 if there is no port, else the port number. If there's a syntax
395 error, leave the incoming address alone, and return 0.
399 host_address_extract_port(uschar *address)
404 /* Handle the "bracketed with colon on the end" format */
408 uschar *rb = address + 1;
409 while (*rb != 0 && *rb != ']') rb++;
410 if (*rb++ == 0) return 0; /* Missing ]; leave invalid address */
413 port = Ustrtol(rb + 1, &endptr, 10);
414 if (*endptr != 0) return 0; /* Invalid port; leave invalid address */
416 else if (*rb != 0) return 0; /* Bad syntax; leave invalid address */
417 memmove(address, address + 1, rb - address - 2);
421 /* Handle the "dot on the end" format */
425 int skip = -3; /* Skip 3 dots in IPv4 addresses */
427 while (*(++address) != 0)
430 if (ch == ':') skip = 0; /* Skip 0 dots in IPv6 addresses */
431 else if (ch == '.' && skip++ >= 0) break;
433 if (*address == 0) return 0;
434 port = Ustrtol(address + 1, &endptr, 10);
435 if (*endptr != 0) return 0; /* Invalid port; leave invalid address */
443 /*************************************************
444 * Get port from a host item's name *
445 *************************************************/
447 /* This function is called when finding the IP address for a host that is in a
448 list of hosts explicitly configured, such as in the manualroute router, or in a
449 fallback hosts list. We see if there is a port specification at the end of the
450 host name, and if so, remove it. A minimum length of 3 is required for the
451 original name; nothing shorter is recognized as having a port.
453 We test for a name ending with a sequence of digits; if preceded by colon we
454 have a port if the character before the colon is ] and the name starts with [
455 or if there are no other colons in the name (i.e. it's not an IPv6 address).
457 Arguments: pointer to the host item
458 Returns: a port number or PORT_NONE
462 host_item_get_port(host_item *h)
466 int len = Ustrlen(h->name);
468 if (len < 3 || (p = h->name + len - 1, !isdigit(*p))) return PORT_NONE;
470 /* Extract potential port number */
475 while (p > h->name + 1 && isdigit(*p))
477 port += (*p-- - '0') * x;
481 /* The smallest value of p at this point is h->name + 1. */
483 if (*p != ':') return PORT_NONE;
485 if (p[-1] == ']' && h->name[0] == '[')
486 h->name = string_copyn(h->name + 1, p - h->name - 2);
487 else if (Ustrchr(h->name, ':') == p)
488 h->name = string_copyn(h->name, p - h->name);
489 else return PORT_NONE;
491 DEBUG(D_route|D_host_lookup) debug_printf("host=%s port=%d\n", h->name, port);
497 #ifndef STAND_ALONE /* Omit when standalone testing */
499 /*************************************************
500 * Build sender_fullhost and sender_rcvhost *
501 *************************************************/
503 /* This function is called when sender_host_name and/or sender_helo_name
504 have been set. Or might have been set - for a local message read off the spool
505 they won't be. In that case, do nothing. Otherwise, set up the fullhost string
508 (a) No sender_host_name or sender_helo_name: "[ip address]"
509 (b) Just sender_host_name: "host_name [ip address]"
510 (c) Just sender_helo_name: "(helo_name) [ip address]" unless helo is IP
511 in which case: "[ip address}"
512 (d) The two are identical: "host_name [ip address]" includes helo = IP
513 (e) The two are different: "host_name (helo_name) [ip address]"
515 If log_incoming_port is set, the sending host's port number is added to the IP
518 This function also builds sender_rcvhost for use in Received: lines, whose
519 syntax is a bit different. This value also includes the RFC 1413 identity.
520 There wouldn't be two different variables if I had got all this right in the
523 Because this data may survive over more than one incoming SMTP message, it has
524 to be in permanent store.
531 host_build_sender_fullhost(void)
533 BOOL show_helo = TRUE;
536 int old_pool = store_pool;
538 if (sender_host_address == NULL) return;
540 store_pool = POOL_PERM;
542 /* Set up address, with or without the port. After discussion, it seems that
543 the only format that doesn't cause trouble is [aaaa]:pppp. However, we can't
544 use this directly as the first item for Received: because it ain't an RFC 2822
547 address = string_sprintf("[%s]:%d", sender_host_address, sender_host_port);
548 if ((log_extra_selector & LX_incoming_port) == 0 || sender_host_port <= 0)
549 *(Ustrrchr(address, ':')) = 0;
551 /* If there's no EHLO/HELO data, we can't show it. */
553 if (sender_helo_name == NULL) show_helo = FALSE;
555 /* If HELO/EHLO was followed by an IP literal, it's messy because of two
556 features of IPv6. Firstly, there's the "IPv6:" prefix (Exim is liberal and
557 doesn't require this, for historical reasons). Secondly, IPv6 addresses may not
558 be given in canonical form, so we have to canonicize them before comparing. As
559 it happens, the code works for both IPv4 and IPv6. */
561 else if (sender_helo_name[0] == '[' &&
562 sender_helo_name[(len=Ustrlen(sender_helo_name))-1] == ']')
567 if (strncmpic(sender_helo_name + 1, US"IPv6:", 5) == 0) offset += 5;
568 if (strncmpic(sender_helo_name + 1, US"IPv4:", 5) == 0) offset += 5;
570 helo_ip = string_copyn(sender_helo_name + offset, len - offset - 1);
572 if (string_is_ip_address(helo_ip, NULL) != 0)
576 uschar ipx[48], ipy[48]; /* large enough for full IPv6 */
578 sizex = host_aton(helo_ip, x);
579 sizey = host_aton(sender_host_address, y);
581 (void)host_nmtoa(sizex, x, -1, ipx, ':');
582 (void)host_nmtoa(sizey, y, -1, ipy, ':');
584 if (strcmpic(ipx, ipy) == 0) show_helo = FALSE;
588 /* Host name is not verified */
590 if (sender_host_name == NULL)
592 uschar *portptr = Ustrstr(address, "]:");
595 int adlen; /* Sun compiler doesn't like ++ in initializers */
597 adlen = (portptr == NULL)? Ustrlen(address) : (++portptr - address);
598 sender_fullhost = (sender_helo_name == NULL)? address :
599 string_sprintf("(%s) %s", sender_helo_name, address);
601 sender_rcvhost = string_cat(NULL, &size, &ptr, address, adlen);
603 if (sender_ident != NULL || show_helo || portptr != NULL)
606 sender_rcvhost = string_cat(sender_rcvhost, &size, &ptr, US" (", 2);
610 sender_rcvhost = string_append(sender_rcvhost, &size, &ptr, 2, US"port=",
614 sender_rcvhost = string_append(sender_rcvhost, &size, &ptr, 2,
615 (firstptr == ptr)? US"helo=" : US" helo=", sender_helo_name);
617 if (sender_ident != NULL)
618 sender_rcvhost = string_append(sender_rcvhost, &size, &ptr, 2,
619 (firstptr == ptr)? US"ident=" : US" ident=", sender_ident);
621 sender_rcvhost = string_cat(sender_rcvhost, &size, &ptr, US")", 1);
624 sender_rcvhost[ptr] = 0; /* string_cat() always leaves room */
626 /* Release store, because string_cat allocated a minimum of 100 bytes that
627 are rarely completely used. */
629 store_reset(sender_rcvhost + ptr + 1);
632 /* Host name is known and verified. Unless we've already found that the HELO
633 data matches the IP address, compare it with the name. */
637 if (show_helo && strcmpic(sender_host_name, sender_helo_name) == 0)
642 sender_fullhost = string_sprintf("%s (%s) %s", sender_host_name,
643 sender_helo_name, address);
644 sender_rcvhost = (sender_ident == NULL)?
645 string_sprintf("%s (%s helo=%s)", sender_host_name,
646 address, sender_helo_name) :
647 string_sprintf("%s\n\t(%s helo=%s ident=%s)", sender_host_name,
648 address, sender_helo_name, sender_ident);
652 sender_fullhost = string_sprintf("%s %s", sender_host_name, address);
653 sender_rcvhost = (sender_ident == NULL)?
654 string_sprintf("%s (%s)", sender_host_name, address) :
655 string_sprintf("%s (%s ident=%s)", sender_host_name, address,
660 store_pool = old_pool;
662 DEBUG(D_host_lookup) debug_printf("sender_fullhost = %s\n", sender_fullhost);
663 DEBUG(D_host_lookup) debug_printf("sender_rcvhost = %s\n", sender_rcvhost);
668 /*************************************************
669 * Build host+ident message *
670 *************************************************/
672 /* Used when logging rejections and various ACL and SMTP incidents. The text
673 return depends on whether sender_fullhost and sender_ident are set or not:
675 no ident, no host => U=unknown
676 no ident, host set => H=sender_fullhost
677 ident set, no host => U=ident
678 ident set, host set => H=sender_fullhost U=ident
681 useflag TRUE if first item to be flagged (H= or U=); if there are two
682 items, the second is always flagged
684 Returns: pointer to a string in big_buffer
688 host_and_ident(BOOL useflag)
690 if (sender_fullhost == NULL)
692 (void)string_format(big_buffer, big_buffer_size, "%s%s", useflag? "U=" : "",
693 (sender_ident == NULL)? US"unknown" : sender_ident);
697 uschar *flag = useflag? US"H=" : US"";
698 uschar *iface = US"";
699 if ((log_extra_selector & LX_incoming_interface) != 0 &&
700 interface_address != NULL)
701 iface = string_sprintf(" I=[%s]:%d", interface_address, interface_port);
702 if (sender_ident == NULL)
703 (void)string_format(big_buffer, big_buffer_size, "%s%s%s",
704 flag, sender_fullhost, iface);
706 (void)string_format(big_buffer, big_buffer_size, "%s%s%s U=%s",
707 flag, sender_fullhost, iface, sender_ident);
712 #endif /* STAND_ALONE */
717 /*************************************************
718 * Build list of local interfaces *
719 *************************************************/
721 /* This function interprets the contents of the local_interfaces or
722 extra_local_interfaces options, and creates an ip_address_item block for each
723 item on the list. There is no special interpretation of any IP addresses; in
724 particular, 0.0.0.0 and ::0 are returned without modification. If any address
725 includes a port, it is set in the block. Otherwise the port value is set to
730 name the name of the option being expanded
732 Returns: a chain of ip_address_items, each containing to a textual
733 version of an IP address, and a port number (host order) or
734 zero if no port was given with the address
738 host_build_ifacelist(const uschar *list, uschar *name)
743 ip_address_item *yield = NULL;
744 ip_address_item *last = NULL;
745 ip_address_item *next;
747 while ((s = string_nextinlist(&list, &sep, buffer, sizeof(buffer))) != NULL)
750 int port = host_address_extract_port(s); /* Leaves just the IP address */
751 if ((ipv = string_is_ip_address(s, NULL)) == 0)
752 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "Malformed IP address \"%s\" in %s",
755 /* Skip IPv6 addresses if IPv6 is disabled. */
757 if (disable_ipv6 && ipv == 6) continue;
759 /* This use of strcpy() is OK because we have checked that s is a valid IP
760 address above. The field in the ip_address_item is large enough to hold an
763 next = store_get(sizeof(ip_address_item));
765 Ustrcpy(next->address, s);
767 next->v6_include_v4 = FALSE;
769 if (yield == NULL) yield = last = next; else
783 /*************************************************
784 * Find addresses on local interfaces *
785 *************************************************/
787 /* This function finds the addresses of local IP interfaces. These are used
788 when testing for routing to the local host. As the function may be called more
789 than once, the list is preserved in permanent store, pointed to by a static
790 variable, to save doing the work more than once per process.
792 The generic list of interfaces is obtained by calling host_build_ifacelist()
793 for local_interfaces and extra_local_interfaces. This list scanned to remove
794 duplicates (which may exist with different ports - not relevant here). If
795 either of the wildcard IP addresses (0.0.0.0 and ::0) are encountered, they are
796 replaced by the appropriate (IPv4 or IPv6) list of actual local interfaces,
797 obtained from os_find_running_interfaces().
800 Returns: a chain of ip_address_items, each containing to a textual
801 version of an IP address; the port numbers are not relevant
805 /* First, a local subfunction to add an interface to a list in permanent store,
806 but only if there isn't a previous copy of that address on the list. */
808 static ip_address_item *
809 add_unique_interface(ip_address_item *list, ip_address_item *ipa)
811 ip_address_item *ipa2;
812 for (ipa2 = list; ipa2 != NULL; ipa2 = ipa2->next)
813 if (Ustrcmp(ipa2->address, ipa->address) == 0) return list;
814 ipa2 = store_get_perm(sizeof(ip_address_item));
821 /* This is the globally visible function */
824 host_find_interfaces(void)
826 ip_address_item *running_interfaces = NULL;
828 if (local_interface_data == NULL)
830 void *reset_item = store_get(0);
831 ip_address_item *dlist = host_build_ifacelist(CUS local_interfaces,
832 US"local_interfaces");
833 ip_address_item *xlist = host_build_ifacelist(CUS extra_local_interfaces,
834 US"extra_local_interfaces");
835 ip_address_item *ipa;
837 if (dlist == NULL) dlist = xlist; else
839 for (ipa = dlist; ipa->next != NULL; ipa = ipa->next);
843 for (ipa = dlist; ipa != NULL; ipa = ipa->next)
845 if (Ustrcmp(ipa->address, "0.0.0.0") == 0 ||
846 Ustrcmp(ipa->address, "::0") == 0)
848 ip_address_item *ipa2;
849 BOOL ipv6 = ipa->address[0] == ':';
850 if (running_interfaces == NULL)
851 running_interfaces = os_find_running_interfaces();
852 for (ipa2 = running_interfaces; ipa2 != NULL; ipa2 = ipa2->next)
854 if ((Ustrchr(ipa2->address, ':') != NULL) == ipv6)
855 local_interface_data = add_unique_interface(local_interface_data,
861 local_interface_data = add_unique_interface(local_interface_data, ipa);
864 debug_printf("Configured local interface: address=%s", ipa->address);
865 if (ipa->port != 0) debug_printf(" port=%d", ipa->port);
870 store_reset(reset_item);
873 return local_interface_data;
880 /*************************************************
881 * Convert network IP address to text *
882 *************************************************/
884 /* Given an IPv4 or IPv6 address in binary, convert it to a text
885 string and return the result in a piece of new store. The address can
886 either be given directly, or passed over in a sockaddr structure. Note
887 that this isn't the converse of host_aton() because of byte ordering
888 differences. See host_nmtoa() below.
891 type if < 0 then arg points to a sockaddr, else
892 either AF_INET or AF_INET6
893 arg points to a sockaddr if type is < 0, or
894 points to an IPv4 address (32 bits), or
895 points to an IPv6 address (128 bits),
896 in both cases, in network byte order
897 buffer if NULL, the result is returned in gotten store;
898 else points to a buffer to hold the answer
899 portptr points to where to put the port number, if non NULL; only
902 Returns: pointer to character string
906 host_ntoa(int type, const void *arg, uschar *buffer, int *portptr)
910 /* The new world. It is annoying that we have to fish out the address from
911 different places in the block, depending on what kind of address it is. It
912 is also a pain that inet_ntop() returns a const uschar *, whereas the IPv4
913 function inet_ntoa() returns just uschar *, and some picky compilers insist
914 on warning if one assigns a const uschar * to a uschar *. Hence the casts. */
917 uschar addr_buffer[46];
920 int family = ((struct sockaddr *)arg)->sa_family;
921 if (family == AF_INET6)
923 struct sockaddr_in6 *sk = (struct sockaddr_in6 *)arg;
924 yield = (uschar *)inet_ntop(family, &(sk->sin6_addr), CS addr_buffer,
925 sizeof(addr_buffer));
926 if (portptr != NULL) *portptr = ntohs(sk->sin6_port);
930 struct sockaddr_in *sk = (struct sockaddr_in *)arg;
931 yield = (uschar *)inet_ntop(family, &(sk->sin_addr), CS addr_buffer,
932 sizeof(addr_buffer));
933 if (portptr != NULL) *portptr = ntohs(sk->sin_port);
938 yield = (uschar *)inet_ntop(type, arg, CS addr_buffer, sizeof(addr_buffer));
941 /* If the result is a mapped IPv4 address, show it in V4 format. */
943 if (Ustrncmp(yield, "::ffff:", 7) == 0) yield += 7;
945 #else /* HAVE_IPV6 */
951 yield = US inet_ntoa(((struct sockaddr_in *)arg)->sin_addr);
952 if (portptr != NULL) *portptr = ntohs(((struct sockaddr_in *)arg)->sin_port);
955 yield = US inet_ntoa(*((struct in_addr *)arg));
958 /* If there is no buffer, put the string into some new store. */
960 if (buffer == NULL) return string_copy(yield);
962 /* Callers of this function with a non-NULL buffer must ensure that it is
963 large enough to hold an IPv6 address, namely, at least 46 bytes. That's what
964 makes this use of strcpy() OK. */
966 Ustrcpy(buffer, yield);
973 /*************************************************
974 * Convert address text to binary *
975 *************************************************/
977 /* Given the textual form of an IP address, convert it to binary in an
978 array of ints. IPv4 addresses occupy one int; IPv6 addresses occupy 4 ints.
979 The result has the first byte in the most significant byte of the first int. In
980 other words, the result is not in network byte order, but in host byte order.
981 As a result, this is not the converse of host_ntoa(), which expects network
982 byte order. See host_nmtoa() below.
985 address points to the textual address, checked for syntax
986 bin points to an array of 4 ints
988 Returns: the number of ints used
992 host_aton(const uschar *address, int *bin)
997 /* Handle IPv6 address, which may end with an IPv4 address. It may also end
998 with a "scope", introduced by a percent sign. This code is NOT enclosed in #if
999 HAVE_IPV6 in order that IPv6 addresses are recognized even if IPv6 is not
1002 if (Ustrchr(address, ':') != NULL)
1004 const uschar *p = address;
1005 const uschar *component[8];
1006 BOOL ipv4_ends = FALSE;
1012 /* If the address starts with a colon, it will start with two colons.
1013 Just lose the first one, which will leave a null first component. */
1017 /* Split the address into components separated by colons. The input address
1018 is supposed to be checked for syntax. There was a case where this was
1019 overlooked; to guard against that happening again, check here and crash if
1020 there are too many components. */
1022 while (*p != 0 && *p != '%')
1024 int len = Ustrcspn(p, ":%");
1025 if (len == 0) nulloffset = ci;
1026 if (ci > 7) log_write(0, LOG_MAIN|LOG_PANIC_DIE,
1027 "Internal error: invalid IPv6 address \"%s\" passed to host_aton()",
1029 component[ci++] = p;
1034 /* If the final component contains a dot, it is a trailing v4 address.
1035 As the syntax is known to be checked, just set up for a trailing
1036 v4 address and restrict the v6 part to 6 components. */
1038 if (Ustrchr(component[ci-1], '.') != NULL)
1040 address = component[--ci];
1046 /* If there are fewer than 6 or 8 components, we have to insert some
1047 more empty ones in the middle. */
1051 int insert_count = v6count - ci;
1052 for (i = v6count-1; i > nulloffset + insert_count; i--)
1053 component[i] = component[i - insert_count];
1054 while (i > nulloffset) component[i--] = US"";
1057 /* Now turn the components into binary in pairs and bung them
1058 into the vector of ints. */
1060 for (i = 0; i < v6count; i += 2)
1061 bin[i/2] = (Ustrtol(component[i], NULL, 16) << 16) +
1062 Ustrtol(component[i+1], NULL, 16);
1064 /* If there was no terminating v4 component, we are done. */
1066 if (!ipv4_ends) return 4;
1069 /* Handle IPv4 address */
1071 (void)sscanf(CS address, "%d.%d.%d.%d", x, x+1, x+2, x+3);
1072 bin[v4offset] = (x[0] << 24) + (x[1] << 16) + (x[2] << 8) + x[3];
1077 /*************************************************
1078 * Apply mask to an IP address *
1079 *************************************************/
1081 /* Mask an address held in 1 or 4 ints, with the ms bit in the ms bit of the
1085 count the number of ints
1086 binary points to the ints to be masked
1087 mask the count of ms bits to leave, or -1 if no masking
1093 host_mask(int count, int *binary, int mask)
1096 if (mask < 0) mask = 99999;
1097 for (i = 0; i < count; i++)
1100 if (mask == 0) wordmask = 0;
1103 wordmask = (-1) << (32 - mask);
1111 binary[i] &= wordmask;
1118 /*************************************************
1119 * Convert masked IP address in ints to text *
1120 *************************************************/
1122 /* We can't use host_ntoa() because it assumes the binary values are in network
1123 byte order, and these are the result of host_aton(), which puts them in ints in
1124 host byte order. Also, we really want IPv6 addresses to be in a canonical
1125 format, so we output them with no abbreviation. In a number of cases we can't
1126 use the normal colon separator in them because it terminates keys in lsearch
1127 files, so we want to use dot instead. There's an argument that specifies what
1128 to use for IPv6 addresses.
1131 count 1 or 4 (number of ints)
1132 binary points to the ints
1133 mask mask value; if < 0 don't add to result
1134 buffer big enough to hold the result
1135 sep component separator character for IPv6 addresses
1137 Returns: the number of characters placed in buffer, not counting
1142 host_nmtoa(int count, int *binary, int mask, uschar *buffer, int sep)
1145 uschar *tt = buffer;
1150 for (i = 24; i >= 0; i -= 8)
1152 sprintf(CS tt, "%d.", (j >> i) & 255);
1158 for (i = 0; i < 4; i++)
1161 sprintf(CS tt, "%04x%c%04x%c", (j >> 16) & 0xffff, sep, j & 0xffff, sep);
1166 tt--; /* lose final separator */
1172 sprintf(CS tt, "/%d", mask);
1181 /*************************************************
1182 * Check port for tls_on_connect *
1183 *************************************************/
1185 /* This function checks whether a given incoming port is configured for tls-
1186 on-connect. It is called from the daemon and from inetd handling. If the global
1187 option tls_on_connect is already set, all ports operate this way. Otherwise, we
1188 check the tls_on_connect_ports option for a list of ports.
1190 Argument: a port number
1191 Returns: TRUE or FALSE
1195 host_is_tls_on_connect_port(int port)
1199 const uschar *list = tls_in.on_connect_ports;
1203 if (tls_in.on_connect) return TRUE;
1205 while ((s = string_nextinlist(&list, &sep, buffer, sizeof(buffer))))
1206 if (Ustrtol(s, &end, 10) == port)
1214 /*************************************************
1215 * Check whether host is in a network *
1216 *************************************************/
1218 /* This function checks whether a given IP address matches a pattern that
1219 represents either a single host, or a network (using CIDR notation). The caller
1220 of this function must check the syntax of the arguments before calling it.
1223 host string representation of the ip-address to check
1224 net string representation of the network, with optional CIDR mask
1225 maskoffset offset to the / that introduces the mask in the key
1226 zero if there is no mask
1229 TRUE the host is inside the network
1230 FALSE the host is NOT inside the network
1234 host_is_in_net(const uschar *host, const uschar *net, int maskoffset)
1240 int size = host_aton(net, address);
1243 /* No mask => all bits to be checked */
1245 if (maskoffset == 0) mlen = 99999; /* Big number */
1246 else mlen = Uatoi(net + maskoffset + 1);
1248 /* Convert the incoming address to binary. */
1250 insize = host_aton(host, incoming);
1252 /* Convert IPv4 addresses given in IPv6 compatible mode, which represent
1253 connections from IPv4 hosts to IPv6 hosts, that is, addresses of the form
1254 ::ffff:<v4address>, to IPv4 format. */
1256 if (insize == 4 && incoming[0] == 0 && incoming[1] == 0 &&
1257 incoming[2] == 0xffff)
1260 incoming[0] = incoming[3];
1263 /* No match if the sizes don't agree. */
1265 if (insize != size) return FALSE;
1267 /* Else do the masked comparison. */
1269 for (i = 0; i < size; i++)
1272 if (mlen == 0) mask = 0;
1275 mask = (-1) << (32 - mlen);
1283 if ((incoming[i] & mask) != (address[i] & mask)) return FALSE;
1291 /*************************************************
1292 * Scan host list for local hosts *
1293 *************************************************/
1295 /* Scan through a chain of addresses and check whether any of them is the
1296 address of an interface on the local machine. If so, remove that address and
1297 any previous ones with the same MX value, and all subsequent ones (which will
1298 have greater or equal MX values) from the chain. Note: marking them as unusable
1299 is NOT the right thing to do because it causes the hosts not to be used for
1300 other domains, for which they may well be correct.
1302 The hosts may be part of a longer chain; we only process those between the
1303 initial pointer and the "last" pointer.
1305 There is also a list of "pseudo-local" host names which are checked against the
1306 host names. Any match causes that host item to be treated the same as one which
1307 matches a local IP address.
1309 If the very first host is a local host, then all MX records had a precedence
1310 greater than or equal to that of the local host. Either there's a problem in
1311 the DNS, or an apparently remote name turned out to be an abbreviation for the
1312 local host. Give a specific return code, and let the caller decide what to do.
1313 Otherwise, give a success code if at least one host address has been found.
1316 host pointer to the first host in the chain
1317 lastptr pointer to pointer to the last host in the chain (may be updated)
1318 removed if not NULL, set TRUE if some local addresses were removed
1322 HOST_FOUND if there is at least one host with an IP address on the chain
1323 and an MX value less than any MX value associated with the
1325 HOST_FOUND_LOCAL if a local host is among the lowest-numbered MX hosts; when
1326 the host addresses were obtained from A records or
1327 gethostbyname(), the MX values are set to -1.
1328 HOST_FIND_FAILED if no valid hosts with set IP addresses were found
1332 host_scan_for_local_hosts(host_item *host, host_item **lastptr, BOOL *removed)
1334 int yield = HOST_FIND_FAILED;
1335 host_item *last = *lastptr;
1336 host_item *prev = NULL;
1339 if (removed != NULL) *removed = FALSE;
1341 if (local_interface_data == NULL) local_interface_data = host_find_interfaces();
1343 for (h = host; h != last->next; h = h->next)
1346 if (hosts_treat_as_local != NULL)
1349 const uschar *save = deliver_domain;
1350 deliver_domain = h->name; /* set $domain */
1351 rc = match_isinlist(string_copylc(h->name), CUSS &hosts_treat_as_local, 0,
1352 &domainlist_anchor, NULL, MCL_DOMAIN, TRUE, NULL);
1353 deliver_domain = save;
1354 if (rc == OK) goto FOUND_LOCAL;
1358 /* It seems that on many operating systems, 0.0.0.0 is treated as a synonym
1359 for 127.0.0.1 and refers to the local host. We therefore force it always to
1360 be treated as local. */
1362 if (h->address != NULL)
1364 ip_address_item *ip;
1365 if (Ustrcmp(h->address, "0.0.0.0") == 0) goto FOUND_LOCAL;
1366 for (ip = local_interface_data; ip != NULL; ip = ip->next)
1367 if (Ustrcmp(h->address, ip->address) == 0) goto FOUND_LOCAL;
1368 yield = HOST_FOUND; /* At least one remote address has been found */
1371 /* Update prev to point to the last host item before any that have
1372 the same MX value as the one we have just considered. */
1374 if (h->next == NULL || h->next->mx != h->mx) prev = h;
1377 return yield; /* No local hosts found: return HOST_FOUND or HOST_FIND_FAILED */
1379 /* A host whose IP address matches a local IP address, or whose name matches
1380 something in hosts_treat_as_local has been found. */
1386 HDEBUG(D_host_lookup) debug_printf((h->mx >= 0)?
1387 "local host has lowest MX\n" :
1388 "local host found for non-MX address\n");
1389 return HOST_FOUND_LOCAL;
1392 HDEBUG(D_host_lookup)
1394 debug_printf("local host in host list - removed hosts:\n");
1395 for (h = prev->next; h != last->next; h = h->next)
1396 debug_printf(" %s %s %d\n", h->name, h->address, h->mx);
1399 if (removed != NULL) *removed = TRUE;
1400 prev->next = last->next;
1408 /*************************************************
1409 * Remove duplicate IPs in host list *
1410 *************************************************/
1412 /* You would think that administrators could set up their DNS records so that
1413 one ended up with a list of unique IP addresses after looking up A or MX
1414 records, but apparently duplication is common. So we scan such lists and
1415 remove the later duplicates. Note that we may get lists in which some host
1416 addresses are not set.
1419 host pointer to the first host in the chain
1420 lastptr pointer to pointer to the last host in the chain (may be updated)
1426 host_remove_duplicates(host_item *host, host_item **lastptr)
1428 while (host != *lastptr)
1430 if (host->address != NULL)
1432 host_item *h = host;
1433 while (h != *lastptr)
1435 if (h->next->address != NULL &&
1436 Ustrcmp(h->next->address, host->address) == 0)
1438 DEBUG(D_host_lookup) debug_printf("duplicate IP address %s (MX=%d) "
1439 "removed\n", host->address, h->next->mx);
1440 if (h->next == *lastptr) *lastptr = h;
1441 h->next = h->next->next;
1446 /* If the last item was removed, host may have become == *lastptr */
1447 if (host != *lastptr) host = host->next;
1454 /*************************************************
1455 * Find sender host name by gethostbyaddr() *
1456 *************************************************/
1458 /* This used to be the only way it was done, but it turns out that not all
1459 systems give aliases for calls to gethostbyaddr() - or one of the modern
1460 equivalents like getipnodebyaddr(). Fortunately, multiple PTR records are rare,
1461 but they can still exist. This function is now used only when a DNS lookup of
1462 the IP address fails, in order to give access to /etc/hosts.
1465 Returns: OK, DEFER, FAIL
1469 host_name_lookup_byaddr(void)
1473 struct hostent *hosts;
1474 struct in_addr addr;
1475 unsigned long time_msec;
1477 if (slow_lookup_log) time_msec = get_time_in_ms();
1479 /* Lookup on IPv6 system */
1482 if (Ustrchr(sender_host_address, ':') != NULL)
1484 struct in6_addr addr6;
1485 if (inet_pton(AF_INET6, CS sender_host_address, &addr6) != 1)
1486 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "unable to parse \"%s\" as an "
1487 "IPv6 address", sender_host_address);
1488 #if HAVE_GETIPNODEBYADDR
1489 hosts = getipnodebyaddr(CS &addr6, sizeof(addr6), AF_INET6, &h_errno);
1491 hosts = gethostbyaddr(CS &addr6, sizeof(addr6), AF_INET6);
1496 if (inet_pton(AF_INET, CS sender_host_address, &addr) != 1)
1497 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "unable to parse \"%s\" as an "
1498 "IPv4 address", sender_host_address);
1499 #if HAVE_GETIPNODEBYADDR
1500 hosts = getipnodebyaddr(CS &addr, sizeof(addr), AF_INET, &h_errno);
1502 hosts = gethostbyaddr(CS &addr, sizeof(addr), AF_INET);
1506 /* Do lookup on IPv4 system */
1509 addr.s_addr = (S_ADDR_TYPE)inet_addr(CS sender_host_address);
1510 hosts = gethostbyaddr(CS(&addr), sizeof(addr), AF_INET);
1513 if ( slow_lookup_log
1514 && (time_msec = get_time_in_ms() - time_msec) > slow_lookup_log
1516 log_long_lookup(US"name", sender_host_address, time_msec);
1518 /* Failed to look up the host. */
1522 HDEBUG(D_host_lookup) debug_printf("IP address lookup failed: h_errno=%d\n",
1524 return (h_errno == TRY_AGAIN || h_errno == NO_RECOVERY) ? DEFER : FAIL;
1527 /* It seems there are some records in the DNS that yield an empty name. We
1528 treat this as non-existent. In some operating systems, this is returned as an
1529 empty string; in others as a single dot. */
1531 if (hosts->h_name == NULL || hosts->h_name[0] == 0 || hosts->h_name[0] == '.')
1533 HDEBUG(D_host_lookup) debug_printf("IP address lookup yielded an empty name: "
1534 "treated as non-existent host name\n");
1538 /* Copy and lowercase the name, which is in static storage in many systems.
1539 Put it in permanent memory. */
1541 s = (uschar *)hosts->h_name;
1542 len = Ustrlen(s) + 1;
1543 t = sender_host_name = store_get_perm(len);
1544 while (*s != 0) *t++ = tolower(*s++);
1547 /* If the host has aliases, build a copy of the alias list */
1549 if (hosts->h_aliases != NULL)
1552 uschar **aliases, **ptr;
1553 for (aliases = USS hosts->h_aliases; *aliases != NULL; aliases++) count++;
1554 ptr = sender_host_aliases = store_get_perm(count * sizeof(uschar *));
1555 for (aliases = USS hosts->h_aliases; *aliases != NULL; aliases++)
1557 uschar *s = *aliases;
1558 int len = Ustrlen(s) + 1;
1559 uschar *t = *ptr++ = store_get_perm(len);
1560 while (*s != 0) *t++ = tolower(*s++);
1571 /*************************************************
1572 * Find host name for incoming call *
1573 *************************************************/
1575 /* Put the name in permanent store, pointed to by sender_host_name. We also set
1576 up a list of alias names, pointed to by sender_host_alias. The list is
1577 NULL-terminated. The incoming address is in sender_host_address, either in
1578 dotted-quad form for IPv4 or in colon-separated form for IPv6.
1580 This function does a thorough check that the names it finds point back to the
1581 incoming IP address. Any that do not are discarded. Note that this is relied on
1582 by the ACL reverse_host_lookup check.
1584 On some systems, get{host,ipnode}byaddr() appears to do this internally, but
1585 this it not universally true. Also, for release 4.30, this function was changed
1586 to do a direct DNS lookup first, by default[1], because it turns out that that
1587 is the only guaranteed way to find all the aliases on some systems. My
1588 experiments indicate that Solaris gethostbyaddr() gives the aliases for but
1591 [1] The actual order is controlled by the host_lookup_order option.
1594 Returns: OK on success, the answer being placed in the global variable
1595 sender_host_name, with any aliases in a list hung off
1597 FAIL if no host name can be found
1598 DEFER if a temporary error was encountered
1600 The variable host_lookup_msg is set to an empty string on sucess, or to a
1601 reason for the failure otherwise, in a form suitable for tagging onto an error
1602 message, and also host_lookup_failed is set TRUE if the lookup failed. If there
1603 was a defer, host_lookup_deferred is set TRUE.
1605 Any dynamically constructed string for host_lookup_msg must be in permanent
1606 store, because it might be used for several incoming messages on the same SMTP
1610 host_name_lookup(void)
1614 uschar *hname, *save_hostname;
1618 const uschar *list = host_lookup_order;
1623 sender_host_dnssec = host_lookup_deferred = host_lookup_failed = FALSE;
1625 HDEBUG(D_host_lookup)
1626 debug_printf("looking up host name for %s\n", sender_host_address);
1628 /* For testing the case when a lookup does not complete, we have a special
1629 reserved IP address. */
1631 if (running_in_test_harness &&
1632 Ustrcmp(sender_host_address, "99.99.99.99") == 0)
1634 HDEBUG(D_host_lookup)
1635 debug_printf("Test harness: host name lookup returns DEFER\n");
1636 host_lookup_deferred = TRUE;
1640 /* Do lookups directly in the DNS or via gethostbyaddr() (or equivalent), in
1641 the order specified by the host_lookup_order option. */
1643 while ((ordername = string_nextinlist(&list, &sep, buffer, sizeof(buffer)))
1646 if (strcmpic(ordername, US"bydns") == 0)
1648 dns_init(FALSE, FALSE, FALSE); /* dnssec ctrl by dns_dnssec_ok glbl */
1649 dns_build_reverse(sender_host_address, buffer);
1650 rc = dns_lookup_timerwrap(&dnsa, buffer, T_PTR, NULL);
1652 /* The first record we come across is used for the name; others are
1653 considered to be aliases. We have to scan twice, in order to find out the
1654 number of aliases. However, if all the names are empty, we will behave as
1655 if failure. (PTR records that yield empty names have been encountered in
1658 if (rc == DNS_SUCCEED)
1660 uschar **aptr = NULL;
1663 int old_pool = store_pool;
1665 /* Ideally we'd check DNSSEC both forward and reverse, but we use the
1666 gethost* routines for forward, so can't do that unless/until we rewrite. */
1667 sender_host_dnssec = dns_is_secure(&dnsa);
1669 debug_printf("Reverse DNS security status: %s\n",
1670 sender_host_dnssec ? "DNSSEC verified (AD)" : "unverified");
1672 store_pool = POOL_PERM; /* Save names in permanent storage */
1674 for (rr = dns_next_rr(&dnsa, &dnss, RESET_ANSWERS);
1676 rr = dns_next_rr(&dnsa, &dnss, RESET_NEXT))
1678 if (rr->type == T_PTR) count++;
1681 /* Get store for the list of aliases. For compatibility with
1682 gethostbyaddr, we make an empty list if there are none. */
1684 aptr = sender_host_aliases = store_get(count * sizeof(uschar *));
1686 /* Re-scan and extract the names */
1688 for (rr = dns_next_rr(&dnsa, &dnss, RESET_ANSWERS);
1690 rr = dns_next_rr(&dnsa, &dnss, RESET_NEXT))
1693 if (rr->type != T_PTR) continue;
1694 s = store_get(ssize);
1696 /* If an overlong response was received, the data will have been
1697 truncated and dn_expand may fail. */
1699 if (dn_expand(dnsa.answer, dnsa.answer + dnsa.answerlen,
1700 (uschar *)(rr->data), (DN_EXPAND_ARG4_TYPE)(s), ssize) < 0)
1702 log_write(0, LOG_MAIN, "host name alias list truncated for %s",
1703 sender_host_address);
1707 store_reset(s + Ustrlen(s) + 1);
1710 HDEBUG(D_host_lookup) debug_printf("IP address lookup yielded an "
1711 "empty name: treated as non-existent host name\n");
1714 if (sender_host_name == NULL) sender_host_name = s;
1716 while (*s != 0) { *s = tolower(*s); s++; }
1719 *aptr = NULL; /* End of alias list */
1720 store_pool = old_pool; /* Reset store pool */
1722 /* If we've found a names, break out of the "order" loop */
1724 if (sender_host_name != NULL) break;
1727 /* If the DNS lookup deferred, we must also defer. */
1729 if (rc == DNS_AGAIN)
1731 HDEBUG(D_host_lookup)
1732 debug_printf("IP address PTR lookup gave temporary error\n");
1733 host_lookup_deferred = TRUE;
1738 /* Do a lookup using gethostbyaddr() - or equivalent */
1740 else if (strcmpic(ordername, US"byaddr") == 0)
1742 HDEBUG(D_host_lookup)
1743 debug_printf("IP address lookup using gethostbyaddr()\n");
1744 rc = host_name_lookup_byaddr();
1747 host_lookup_deferred = TRUE;
1748 return rc; /* Can't carry on */
1750 if (rc == OK) break; /* Found a name */
1752 } /* Loop for bydns/byaddr scanning */
1754 /* If we have failed to find a name, return FAIL and log when required.
1755 NB host_lookup_msg must be in permanent store. */
1757 if (sender_host_name == NULL)
1759 if (host_checking || !log_testing_mode)
1760 log_write(L_host_lookup_failed, LOG_MAIN, "no host name found for IP "
1761 "address %s", sender_host_address);
1762 host_lookup_msg = US" (failed to find host name from IP address)";
1763 host_lookup_failed = TRUE;
1767 HDEBUG(D_host_lookup)
1769 uschar **aliases = sender_host_aliases;
1770 debug_printf("IP address lookup yielded \"%s\"\n", sender_host_name);
1771 while (*aliases != NULL) debug_printf(" alias \"%s\"\n", *aliases++);
1774 /* We need to verify that a forward lookup on the name we found does indeed
1775 correspond to the address. This is for security: in principle a malefactor who
1776 happened to own a reverse zone could set it to point to any names at all.
1778 This code was present in versions of Exim before 3.20. At that point I took it
1779 out because I thought that gethostbyaddr() did the check anyway. It turns out
1780 that this isn't always the case, so it's coming back in at 4.01. This version
1781 is actually better, because it also checks aliases.
1783 The code was made more robust at release 4.21. Prior to that, it accepted all
1784 the names if any of them had the correct IP address. Now the code checks all
1785 the names, and accepts only those that have the correct IP address. */
1787 save_hostname = sender_host_name; /* Save for error messages */
1788 aliases = sender_host_aliases;
1789 for (hname = sender_host_name; hname != NULL; hname = *aliases++)
1799 /* When called with the last argument FALSE, host_find_byname() won't return
1800 HOST_FOUND_LOCAL. If the incoming address is an IPv4 address expressed in
1801 IPv6 format, we must compare the IPv4 part to any IPv4 addresses. */
1803 if ((rc = host_find_byname(&h, NULL, 0, NULL, FALSE)) == HOST_FOUND)
1806 HDEBUG(D_host_lookup) debug_printf("checking addresses for %s\n", hname);
1807 for (hh = &h; hh != NULL; hh = hh->next)
1809 if (host_is_in_net(hh->address, sender_host_address, 0))
1811 HDEBUG(D_host_lookup) debug_printf(" %s OK\n", hh->address);
1817 HDEBUG(D_host_lookup) debug_printf(" %s\n", hh->address);
1820 if (!ok) HDEBUG(D_host_lookup)
1821 debug_printf("no IP address for %s matched %s\n", hname,
1822 sender_host_address);
1824 else if (rc == HOST_FIND_AGAIN)
1826 HDEBUG(D_host_lookup) debug_printf("temporary error for host name lookup\n");
1827 host_lookup_deferred = TRUE;
1828 sender_host_name = NULL;
1833 HDEBUG(D_host_lookup) debug_printf("no IP addresses found for %s\n", hname);
1836 /* If this name is no good, and it's the sender name, set it null pro tem;
1837 if it's an alias, just remove it from the list. */
1841 if (hname == sender_host_name) sender_host_name = NULL; else
1843 uschar **a; /* Don't amalgamate - some */
1844 a = --aliases; /* compilers grumble */
1845 while (*a != NULL) { *a = a[1]; a++; }
1850 /* If sender_host_name == NULL, it means we didn't like the name. Replace
1851 it with the first alias, if there is one. */
1853 if (sender_host_name == NULL && *sender_host_aliases != NULL)
1854 sender_host_name = *sender_host_aliases++;
1856 /* If we now have a main name, all is well. */
1858 if (sender_host_name != NULL) return OK;
1860 /* We have failed to find an address that matches. */
1862 HDEBUG(D_host_lookup)
1863 debug_printf("%s does not match any IP address for %s\n",
1864 sender_host_address, save_hostname);
1866 /* This message must be in permanent store */
1868 old_pool = store_pool;
1869 store_pool = POOL_PERM;
1870 host_lookup_msg = string_sprintf(" (%s does not match any IP address for %s)",
1871 sender_host_address, save_hostname);
1872 store_pool = old_pool;
1873 host_lookup_failed = TRUE;
1880 /*************************************************
1881 * Find IP address(es) for host by name *
1882 *************************************************/
1884 /* The input is a host_item structure with the name filled in and the address
1885 field set to NULL. We use gethostbyname() or getipnodebyname() or
1886 gethostbyname2(), as appropriate. Of course, these functions may use the DNS,
1887 but they do not do MX processing. It appears, however, that in some systems the
1888 current setting of resolver options is used when one of these functions calls
1889 the resolver. For this reason, we call dns_init() at the start, with arguments
1890 influenced by bits in "flags", just as we do for host_find_bydns().
1892 The second argument provides a host list (usually an IP list) of hosts to
1893 ignore. This makes it possible to ignore IPv6 link-local addresses or loopback
1894 addresses in unreasonable places.
1896 The lookup may result in a change of name. For compatibility with the dns
1897 lookup, return this via fully_qualified_name as well as updating the host item.
1898 The lookup may also yield more than one IP address, in which case chain on
1899 subsequent host_item structures.
1902 host a host item with the name and MX filled in;
1903 the address is to be filled in;
1904 multiple IP addresses cause other host items to be
1906 ignore_target_hosts a list of hosts to ignore
1907 flags HOST_FIND_QUALIFY_SINGLE ) passed to
1908 HOST_FIND_SEARCH_PARENTS ) dns_init()
1909 fully_qualified_name if not NULL, set to point to host name for
1910 compatibility with host_find_bydns
1911 local_host_check TRUE if a check for the local host is wanted
1913 Returns: HOST_FIND_FAILED Failed to find the host or domain
1914 HOST_FIND_AGAIN Try again later
1915 HOST_FOUND Host found - data filled in
1916 HOST_FOUND_LOCAL Host found and is the local host
1920 host_find_byname(host_item *host, const uschar *ignore_target_hosts, int flags,
1921 const uschar **fully_qualified_name, BOOL local_host_check)
1923 int i, yield, times;
1925 host_item *last = NULL;
1926 BOOL temp_error = FALSE;
1931 /* If we are in the test harness, a name ending in .test.again.dns always
1932 forces a temporary error response, unless the name is in
1933 dns_again_means_nonexist. */
1935 if (running_in_test_harness)
1937 const uschar *endname = host->name + Ustrlen(host->name);
1938 if (Ustrcmp(endname - 14, "test.again.dns") == 0) goto RETURN_AGAIN;
1941 /* Make sure DNS options are set as required. This appears to be necessary in
1942 some circumstances when the get..byname() function actually calls the DNS. */
1944 dns_init((flags & HOST_FIND_QUALIFY_SINGLE) != 0,
1945 (flags & HOST_FIND_SEARCH_PARENTS) != 0,
1946 FALSE); /*XXX dnssec? */
1948 /* In an IPv6 world, unless IPv6 has been disabled, we need to scan for both
1949 kinds of address, so go round the loop twice. Note that we have ensured that
1950 AF_INET6 is defined even in an IPv4 world, which makes for slightly tidier
1951 code. However, if dns_ipv4_lookup matches the domain, we also just do IPv4
1952 lookups here (except when testing standalone). */
1959 (dns_ipv4_lookup != NULL &&
1960 match_isinlist(host->name, CUSS &dns_ipv4_lookup, 0, NULL, NULL,
1961 MCL_DOMAIN, TRUE, NULL) == OK))
1964 { af = AF_INET; times = 1; }
1966 { af = AF_INET6; times = 2; }
1968 /* No IPv6 support */
1970 #else /* HAVE_IPV6 */
1972 #endif /* HAVE_IPV6 */
1974 /* Initialize the flag that gets set for DNS syntax check errors, so that the
1975 interface to this function can be similar to host_find_bydns. */
1977 host_find_failed_syntax = FALSE;
1979 /* Loop to look up both kinds of address in an IPv6 world */
1981 for (i = 1; i <= times;
1983 af = AF_INET, /* If 2 passes, IPv4 on the second */
1989 struct hostent *hostdata;
1990 unsigned long time_msec;
1993 printf("Looking up: %s\n", host->name);
1996 if (slow_lookup_log) time_msec = get_time_in_ms();
1999 if (running_in_test_harness)
2000 hostdata = host_fake_gethostbyname(host->name, af, &error_num);
2003 #if HAVE_GETIPNODEBYNAME
2004 hostdata = getipnodebyname(CS host->name, af, 0, &error_num);
2006 hostdata = gethostbyname2(CS host->name, af);
2007 error_num = h_errno;
2011 #else /* not HAVE_IPV6 */
2012 if (running_in_test_harness)
2013 hostdata = host_fake_gethostbyname(host->name, AF_INET, &error_num);
2016 hostdata = gethostbyname(CS host->name);
2017 error_num = h_errno;
2019 #endif /* HAVE_IPV6 */
2022 && (time_msec = get_time_in_ms() - time_msec) > slow_lookup_log)
2023 log_long_lookup(US"name", host->name, time_msec);
2025 if (hostdata == NULL)
2030 case HOST_NOT_FOUND: error = US"HOST_NOT_FOUND"; break;
2031 case TRY_AGAIN: error = US"TRY_AGAIN"; break;
2032 case NO_RECOVERY: error = US"NO_RECOVERY"; break;
2033 case NO_DATA: error = US"NO_DATA"; break;
2034 #if NO_DATA != NO_ADDRESS
2035 case NO_ADDRESS: error = US"NO_ADDRESS"; break;
2037 default: error = US"?"; break;
2040 DEBUG(D_host_lookup) debug_printf("%s returned %d (%s)\n",
2042 #if HAVE_GETIPNODEBYNAME
2043 (af == AF_INET6)? "getipnodebyname(af=inet6)" : "getipnodebyname(af=inet)",
2045 (af == AF_INET6)? "gethostbyname2(af=inet6)" : "gethostbyname2(af=inet)",
2052 if (error_num == TRY_AGAIN || error_num == NO_RECOVERY) temp_error = TRUE;
2055 if ((hostdata->h_addr_list)[0] == NULL) continue;
2057 /* Replace the name with the fully qualified one if necessary, and fill in
2058 the fully_qualified_name pointer. */
2060 if (hostdata->h_name[0] != 0 &&
2061 Ustrcmp(host->name, hostdata->h_name) != 0)
2062 host->name = string_copy_dnsdomain((uschar *)hostdata->h_name);
2063 if (fully_qualified_name != NULL) *fully_qualified_name = host->name;
2065 /* Get the list of addresses. IPv4 and IPv6 addresses can be distinguished
2066 by their different lengths. Scan the list, ignoring any that are to be
2067 ignored, and build a chain from the rest. */
2069 ipv4_addr = hostdata->h_length == sizeof(struct in_addr);
2071 for (addrlist = USS hostdata->h_addr_list; *addrlist != NULL; addrlist++)
2073 uschar *text_address =
2074 host_ntoa(ipv4_addr? AF_INET:AF_INET6, *addrlist, NULL, NULL);
2077 if (ignore_target_hosts != NULL &&
2078 verify_check_this_host(&ignore_target_hosts, NULL, host->name,
2079 text_address, NULL) == OK)
2081 DEBUG(D_host_lookup)
2082 debug_printf("ignored host %s [%s]\n", host->name, text_address);
2087 /* If this is the first address, last == NULL and we put the data in the
2092 host->address = text_address;
2093 host->port = PORT_NONE;
2094 host->status = hstatus_unknown;
2095 host->why = hwhy_unknown;
2096 host->dnssec = DS_UNK;
2100 /* Else add further host item blocks for any other addresses, keeping
2105 host_item *next = store_get(sizeof(host_item));
2106 next->name = host->name;
2107 next->mx = host->mx;
2108 next->address = text_address;
2109 next->port = PORT_NONE;
2110 next->status = hstatus_unknown;
2111 next->why = hwhy_unknown;
2112 next->dnssec = DS_UNK;
2114 next->next = last->next;
2121 /* If no hosts were found, the address field in the original host block will be
2122 NULL. If temp_error is set, at least one of the lookups gave a temporary error,
2123 so we pass that back. */
2125 if (host->address == NULL)
2129 (message_id[0] == 0 && smtp_in != NULL)?
2130 string_sprintf("no IP address found for host %s (during %s)", host->name,
2131 smtp_get_connection_info()) :
2133 string_sprintf("no IP address found for host %s", host->name);
2135 HDEBUG(D_host_lookup) debug_printf("%s\n", msg);
2136 if (temp_error) goto RETURN_AGAIN;
2137 if (host_checking || !log_testing_mode)
2138 log_write(L_host_lookup_failed, LOG_MAIN, "%s", msg);
2139 return HOST_FIND_FAILED;
2142 /* Remove any duplicate IP addresses, then check to see if this is the local
2143 host if required. */
2145 host_remove_duplicates(host, &last);
2146 yield = local_host_check?
2147 host_scan_for_local_hosts(host, &last, NULL) : HOST_FOUND;
2149 HDEBUG(D_host_lookup)
2152 if (fully_qualified_name != NULL)
2153 debug_printf("fully qualified name = %s\n", *fully_qualified_name);
2154 debug_printf("%s looked up these IP addresses:\n",
2156 #if HAVE_GETIPNODEBYNAME
2165 for (h = host; h != last->next; h = h->next)
2166 debug_printf(" name=%s address=%s\n", h->name,
2167 (h->address == NULL)? US"<null>" : h->address);
2170 /* Return the found status. */
2174 /* Handle the case when there is a temporary error. If the name matches
2175 dns_again_means_nonexist, return permanent rather than temporary failure. */
2181 const uschar *save = deliver_domain;
2182 deliver_domain = host->name; /* set $domain */
2183 rc = match_isinlist(host->name, CUSS &dns_again_means_nonexist, 0, NULL, NULL,
2184 MCL_DOMAIN, TRUE, NULL);
2185 deliver_domain = save;
2188 DEBUG(D_host_lookup) debug_printf("%s is in dns_again_means_nonexist: "
2189 "returning HOST_FIND_FAILED\n", host->name);
2190 return HOST_FIND_FAILED;
2193 return HOST_FIND_AGAIN;
2199 /*************************************************
2200 * Fill in a host address from the DNS *
2201 *************************************************/
2203 /* Given a host item, with its name, port and mx fields set, and its address
2204 field set to NULL, fill in its IP address from the DNS. If it is multi-homed,
2205 create additional host items for the additional addresses, copying all the
2206 other fields, and randomizing the order.
2208 On IPv6 systems, A6 records are sought first (but only if support for A6 is
2209 configured - they may never become mainstream), then AAAA records are sought,
2210 and finally A records are sought as well.
2212 The host name may be changed if the DNS returns a different name - e.g. fully
2213 qualified or changed via CNAME. If fully_qualified_name is not NULL, dns_lookup
2214 ensures that it points to the fully qualified name. However, this is the fully
2215 qualified version of the original name; if a CNAME is involved, the actual
2216 canonical host name may be different again, and so we get it directly from the
2217 relevant RR. Note that we do NOT change the mx field of the host item in this
2218 function as it may be called to set the addresses of hosts taken from MX
2222 host points to the host item we're filling in
2223 lastptr points to pointer to last host item in a chain of
2224 host items (may be updated if host is last and gets
2225 extended because multihomed)
2226 ignore_target_hosts list of hosts to ignore
2227 allow_ip if TRUE, recognize an IP address and return it
2228 fully_qualified_name if not NULL, return fully qualified name here if
2229 the contents are different (i.e. it must be preset
2231 dnnssec_require if TRUE check the DNS result AD bit
2233 Returns: HOST_FIND_FAILED couldn't find A record
2234 HOST_FIND_AGAIN try again later
2235 HOST_FOUND found AAAA and/or A record(s)
2236 HOST_IGNORED found, but all IPs ignored
2240 set_address_from_dns(host_item *host, host_item **lastptr,
2241 const uschar *ignore_target_hosts, BOOL allow_ip,
2242 const uschar **fully_qualified_name,
2243 BOOL dnssec_request, BOOL dnssec_require)
2246 host_item *thishostlast = NULL; /* Indicates not yet filled in anything */
2247 BOOL v6_find_again = FALSE;
2250 /* If allow_ip is set, a name which is an IP address returns that value
2251 as its address. This is used for MX records when allow_mx_to_ip is set, for
2252 those sites that feel they have to flaunt the RFC rules. */
2254 if (allow_ip && string_is_ip_address(host->name, NULL) != 0)
2257 if (ignore_target_hosts != NULL &&
2258 verify_check_this_host(&ignore_target_hosts, NULL, host->name,
2259 host->name, NULL) == OK)
2260 return HOST_IGNORED;
2263 host->address = host->name;
2267 /* On an IPv6 system, unless IPv6 is disabled, go round the loop up to three
2268 times, looking for A6 and AAAA records the first two times. However, unless
2269 doing standalone testing, we force an IPv4 lookup if the domain matches
2270 dns_ipv4_lookup is set. Since A6 records look like being abandoned, support
2271 them only if explicitly configured to do so. On an IPv4 system, go round the
2272 loop once only, looking only for A records. */
2276 if (disable_ipv6 || (dns_ipv4_lookup != NULL &&
2277 match_isinlist(host->name, CUSS &dns_ipv4_lookup, 0, NULL, NULL,
2278 MCL_DOMAIN, TRUE, NULL) == OK))
2279 i = 0; /* look up A records only */
2281 #endif /* STAND_ALONE */
2283 i = 1; /* look up AAAA and A records */
2285 /* The IPv4 world */
2287 #else /* HAVE_IPV6 */
2288 i = 0; /* look up A records only */
2289 #endif /* HAVE_IPV6 */
2293 static int types[] = { T_A, T_AAAA, T_A6 };
2294 int type = types[i];
2295 int randoffset = (i == 0)? 500 : 0; /* Ensures v6 sorts before v4 */
2299 int rc = dns_lookup_timerwrap(&dnsa, host->name, type, fully_qualified_name);
2300 lookup_dnssec_authenticated = !dnssec_request ? NULL
2301 : dns_is_secure(&dnsa) ? US"yes" : US"no";
2303 /* We want to return HOST_FIND_AGAIN if one of the A, A6, or AAAA lookups
2304 fails or times out, but not if another one succeeds. (In the early
2305 IPv6 days there are name servers that always fail on AAAA, but are happy
2306 to give out an A record. We want to proceed with that A record.) */
2308 if (rc != DNS_SUCCEED)
2310 if (i == 0) /* Just tried for an A record, i.e. end of loop */
2312 if (host->address != NULL) return HOST_FOUND; /* A6 or AAAA was found */
2313 if (rc == DNS_AGAIN || rc == DNS_FAIL || v6_find_again)
2314 return HOST_FIND_AGAIN;
2315 return HOST_FIND_FAILED; /* DNS_NOMATCH or DNS_NODATA */
2318 /* Tried for an A6 or AAAA record: remember if this was a temporary
2319 error, and look for the next record type. */
2321 if (rc != DNS_NOMATCH && rc != DNS_NODATA) v6_find_again = TRUE;
2327 if (dns_is_secure(&dnsa))
2329 DEBUG(D_host_lookup) debug_printf("%s A DNSSEC\n", host->name);
2330 if (host->dnssec == DS_UNK) /* set in host_find_bydns() */
2331 host->dnssec = DS_YES;
2337 log_write(L_host_lookup_failed, LOG_MAIN,
2338 "dnssec fail on %s for %.256s",
2339 i>1 ? "A6" : i>0 ? "AAAA" : "A", host->name);
2342 if (host->dnssec == DS_YES) /* set in host_find_bydns() */
2344 DEBUG(D_host_lookup) debug_printf("%s A cancel DNSSEC\n", host->name);
2345 host->dnssec = DS_NO;
2346 lookup_dnssec_authenticated = US"no";
2351 /* Lookup succeeded: fill in the given host item with the first non-ignored
2352 address found; create additional items for any others. A single A6 record
2353 may generate more than one address. The lookup had a chance to update the
2354 fqdn; we do not want any later times round the loop to do so. */
2356 fully_qualified_name = NULL;
2358 for (rr = dns_next_rr(&dnsa, &dnss, RESET_ANSWERS);
2360 rr = dns_next_rr(&dnsa, &dnss, RESET_NEXT))
2362 if (rr->type == type)
2364 /* dns_address *da = dns_address_from_rr(&dnsa, rr); */
2367 da = dns_address_from_rr(&dnsa, rr);
2369 DEBUG(D_host_lookup)
2372 debug_printf("no addresses extracted from A6 RR for %s\n",
2376 /* This loop runs only once for A and AAAA records, but may run
2377 several times for an A6 record that generated multiple addresses. */
2379 for (; da != NULL; da = da->next)
2382 if (ignore_target_hosts != NULL &&
2383 verify_check_this_host(&ignore_target_hosts, NULL,
2384 host->name, da->address, NULL) == OK)
2386 DEBUG(D_host_lookup)
2387 debug_printf("ignored host %s [%s]\n", host->name, da->address);
2392 /* If this is the first address, stick it in the given host block,
2393 and change the name if the returned RR has a different name. */
2395 if (thishostlast == NULL)
2397 if (strcmpic(host->name, rr->name) != 0)
2398 host->name = string_copy_dnsdomain(rr->name);
2399 host->address = da->address;
2400 host->sort_key = host->mx * 1000 + random_number(500) + randoffset;
2401 host->status = hstatus_unknown;
2402 host->why = hwhy_unknown;
2403 thishostlast = host;
2406 /* Not the first address. Check for, and ignore, duplicates. Then
2407 insert in the chain at a random point. */
2414 /* End of our local chain is specified by "thishostlast". */
2416 for (next = host;; next = next->next)
2418 if (Ustrcmp(CS da->address, next->address) == 0) break;
2419 if (next == thishostlast) { next = NULL; break; }
2421 if (next != NULL) continue; /* With loop for next address */
2423 /* Not a duplicate */
2425 new_sort_key = host->mx * 1000 + random_number(500) + randoffset;
2426 next = store_get(sizeof(host_item));
2428 /* New address goes first: insert the new block after the first one
2429 (so as not to disturb the original pointer) but put the new address
2430 in the original block. */
2432 if (new_sort_key < host->sort_key)
2434 *next = *host; /* Copies port */
2436 host->address = da->address;
2437 host->sort_key = new_sort_key;
2438 if (thishostlast == host) thishostlast = next; /* Local last */
2439 if (*lastptr == host) *lastptr = next; /* Global last */
2442 /* Otherwise scan down the addresses for this host to find the
2443 one to insert after. */
2447 host_item *h = host;
2448 while (h != thishostlast)
2450 if (new_sort_key < h->next->sort_key) break;
2453 *next = *h; /* Copies port */
2455 next->address = da->address;
2456 next->sort_key = new_sort_key;
2457 if (h == thishostlast) thishostlast = next; /* Local last */
2458 if (h == *lastptr) *lastptr = next; /* Global last */
2466 /* Control gets here only if the third lookup (the A record) succeeded.
2467 However, the address may not be filled in if it was ignored. */
2469 return (host->address == NULL)? HOST_IGNORED : HOST_FOUND;
2475 /*************************************************
2476 * Find IP addresses and host names via DNS *
2477 *************************************************/
2479 /* The input is a host_item structure with the name field filled in and the
2480 address field set to NULL. This may be in a chain of other host items. The
2481 lookup may result in more than one IP address, in which case we must created
2482 new host blocks for the additional addresses, and insert them into the chain.
2483 The original name may not be fully qualified. Use the fully_qualified_name
2484 argument to return the official name, as returned by the resolver.
2487 host point to initial host item
2488 ignore_target_hosts a list of hosts to ignore
2489 whichrrs flags indicating which RRs to look for:
2490 HOST_FIND_BY_SRV => look for SRV
2491 HOST_FIND_BY_MX => look for MX
2492 HOST_FIND_BY_A => look for A or AAAA
2493 also flags indicating how the lookup is done
2494 HOST_FIND_QUALIFY_SINGLE ) passed to the
2495 HOST_FIND_SEARCH_PARENTS ) resolver
2496 srv_service when SRV used, the service name
2497 srv_fail_domains DNS errors for these domains => assume nonexist
2498 mx_fail_domains DNS errors for these domains => assume nonexist
2499 dnssec_request_domains => make dnssec request
2500 dnssec_require_domains => ditto and nonexist failures
2501 fully_qualified_name if not NULL, return fully-qualified name
2502 removed set TRUE if local host was removed from the list
2504 Returns: HOST_FIND_FAILED Failed to find the host or domain;
2505 if there was a syntax error,
2506 host_find_failed_syntax is set.
2507 HOST_FIND_AGAIN Could not resolve at this time
2508 HOST_FOUND Host found
2509 HOST_FOUND_LOCAL The lowest MX record points to this
2510 machine, if MX records were found, or
2511 an A record that was found contains
2512 an address of the local host
2516 host_find_bydns(host_item *host, const uschar *ignore_target_hosts, int whichrrs,
2517 uschar *srv_service, uschar *srv_fail_domains, uschar *mx_fail_domains,
2518 uschar *dnssec_request_domains, uschar *dnssec_require_domains,
2519 const uschar **fully_qualified_name, BOOL *removed)
2521 host_item *h, *last;
2528 BOOL dnssec_require = match_isinlist(host->name, CUSS &dnssec_require_domains,
2529 0, NULL, NULL, MCL_DOMAIN, TRUE, NULL) == OK;
2530 BOOL dnssec_request = dnssec_require
2531 || match_isinlist(host->name, CUSS &dnssec_request_domains,
2532 0, NULL, NULL, MCL_DOMAIN, TRUE, NULL) == OK;
2533 dnssec_status_t dnssec;
2535 /* Set the default fully qualified name to the incoming name, initialize the
2536 resolver if necessary, set up the relevant options, and initialize the flag
2537 that gets set for DNS syntax check errors. */
2539 if (fully_qualified_name != NULL) *fully_qualified_name = host->name;
2540 dns_init((whichrrs & HOST_FIND_QUALIFY_SINGLE) != 0,
2541 (whichrrs & HOST_FIND_SEARCH_PARENTS) != 0,
2544 host_find_failed_syntax = FALSE;
2546 /* First, if requested, look for SRV records. The service name is given; we
2547 assume TCP progocol. DNS domain names are constrained to a maximum of 256
2548 characters, so the code below should be safe. */
2550 if ((whichrrs & HOST_FIND_BY_SRV) != 0)
2553 uschar *temp_fully_qualified_name = buffer;
2556 (void)sprintf(CS buffer, "_%s._tcp.%n%.256s", srv_service, &prefix_length,
2560 /* Search for SRV records. If the fully qualified name is different to
2561 the input name, pass back the new original domain, without the prepended
2565 lookup_dnssec_authenticated = NULL;
2566 rc = dns_lookup_timerwrap(&dnsa, buffer, ind_type, CUSS &temp_fully_qualified_name);
2570 if (dns_is_secure(&dnsa))
2571 { dnssec = DS_YES; lookup_dnssec_authenticated = US"yes"; }
2573 { dnssec = DS_NO; lookup_dnssec_authenticated = US"no"; }
2576 if (temp_fully_qualified_name != buffer && fully_qualified_name != NULL)
2577 *fully_qualified_name = temp_fully_qualified_name + prefix_length;
2579 /* On DNS failures, we give the "try again" error unless the domain is
2580 listed as one for which we continue. */
2582 if (rc == DNS_SUCCEED && dnssec_require && !dns_is_secure(&dnsa))
2584 log_write(L_host_lookup_failed, LOG_MAIN,
2585 "dnssec fail on SRV for %.256s", host->name);
2588 if (rc == DNS_FAIL || rc == DNS_AGAIN)
2591 if (match_isinlist(host->name, CUSS &srv_fail_domains, 0, NULL, NULL,
2592 MCL_DOMAIN, TRUE, NULL) != OK)
2594 { yield = HOST_FIND_AGAIN; goto out; }
2595 DEBUG(D_host_lookup) debug_printf("DNS_%s treated as DNS_NODATA "
2596 "(domain in srv_fail_domains)\n", (rc == DNS_FAIL)? "FAIL":"AGAIN");
2600 /* If we did not find any SRV records, search the DNS for MX records, if
2601 requested to do so. If the result is DNS_NOMATCH, it means there is no such
2602 domain, and there's no point in going on to look for address records with the
2603 same domain. The result will be DNS_NODATA if the domain exists but has no MX
2604 records. On DNS failures, we give the "try again" error unless the domain is
2605 listed as one for which we continue. */
2607 if (rc != DNS_SUCCEED && (whichrrs & HOST_FIND_BY_MX) != 0)
2611 lookup_dnssec_authenticated = NULL;
2612 rc = dns_lookup_timerwrap(&dnsa, host->name, ind_type, fully_qualified_name);
2616 if (dns_is_secure(&dnsa))
2618 DEBUG(D_host_lookup) debug_printf("%s MX DNSSEC\n", host->name);
2619 dnssec = DS_YES; lookup_dnssec_authenticated = US"yes";
2623 dnssec = DS_NO; lookup_dnssec_authenticated = US"no";
2630 yield = HOST_FIND_FAILED; goto out;
2633 if (!dnssec_require || dns_is_secure(&dnsa))
2635 log_write(L_host_lookup_failed, LOG_MAIN,
2636 "dnssec fail on MX for %.256s", host->name);
2643 if (match_isinlist(host->name, CUSS &mx_fail_domains, 0, NULL, NULL,
2644 MCL_DOMAIN, TRUE, NULL) != OK)
2646 { yield = HOST_FIND_AGAIN; goto out; }
2647 DEBUG(D_host_lookup) debug_printf("DNS_%s treated as DNS_NODATA "
2648 "(domain in mx_fail_domains)\n", (rc == DNS_FAIL)? "FAIL":"AGAIN");
2653 /* If we haven't found anything yet, and we are requested to do so, try for an
2654 A or AAAA record. If we find it (or them) check to see that it isn't the local
2657 if (rc != DNS_SUCCEED)
2659 if ((whichrrs & HOST_FIND_BY_A) == 0)
2661 DEBUG(D_host_lookup) debug_printf("Address records are not being sought\n");
2662 yield = HOST_FIND_FAILED;
2666 last = host; /* End of local chainlet */
2668 host->port = PORT_NONE;
2669 host->dnssec = DS_UNK;
2670 lookup_dnssec_authenticated = NULL;
2671 rc = set_address_from_dns(host, &last, ignore_target_hosts, FALSE,
2672 fully_qualified_name, dnssec_request, dnssec_require);
2674 /* If one or more address records have been found, check that none of them
2675 are local. Since we know the host items all have their IP addresses
2676 inserted, host_scan_for_local_hosts() can only return HOST_FOUND or
2677 HOST_FOUND_LOCAL. We do not need to scan for duplicate IP addresses here,
2678 because set_address_from_dns() removes them. */
2680 if (rc == HOST_FOUND)
2681 rc = host_scan_for_local_hosts(host, &last, removed);
2683 if (rc == HOST_IGNORED) rc = HOST_FIND_FAILED; /* No special action */
2685 DEBUG(D_host_lookup)
2688 if (host->address != NULL)
2690 if (fully_qualified_name != NULL)
2691 debug_printf("fully qualified name = %s\n", *fully_qualified_name);
2692 for (h = host; h != last->next; h = h->next)
2693 debug_printf("%s %s mx=%d sort=%d %s\n", h->name,
2694 (h->address == NULL)? US"<null>" : h->address, h->mx, h->sort_key,
2695 (h->status >= hstatus_unusable)? US"*" : US"");
2703 /* We have found one or more MX or SRV records. Sort them according to
2704 precedence. Put the data for the first one into the existing host block, and
2705 insert new host_item blocks into the chain for the remainder. For equal
2706 precedences one is supposed to randomize the order. To make this happen, the
2707 sorting is actually done on the MX value * 1000 + a random number. This is put
2708 into a host field called sort_key.
2710 In the case of hosts with both IPv6 and IPv4 addresses, we want to choose the
2711 IPv6 address in preference. At this stage, we don't know what kind of address
2712 the host has. We choose a random number < 500; if later we find an A record
2713 first, we add 500 to the random number. Then for any other address records, we
2714 use random numbers in the range 0-499 for AAAA records and 500-999 for A
2717 At this point we remove any duplicates that point to the same host, retaining
2718 only the one with the lowest precedence. We cannot yet check for precedence
2719 greater than that of the local host, because that test cannot be properly done
2720 until the addresses have been found - an MX record may point to a name for this
2721 host which is not the primary hostname. */
2723 last = NULL; /* Indicates that not even the first item is filled yet */
2725 for (rr = dns_next_rr(&dnsa, &dnss, RESET_ANSWERS);
2727 rr = dns_next_rr(&dnsa, &dnss, RESET_NEXT))
2730 int weight = 0; /* For SRV records */
2731 int port = PORT_NONE;
2732 uschar *s; /* MUST be unsigned for GETSHORT */
2735 if (rr->type != ind_type) continue;
2737 GETSHORT(precedence, s); /* Pointer s is advanced */
2739 /* For MX records, we use a random "weight" which causes multiple records of
2740 the same precedence to sort randomly. */
2742 if (ind_type == T_MX)
2743 weight = random_number(500);
2745 /* SRV records are specified with a port and a weight. The weight is used
2746 in a special algorithm. However, to start with, we just use it to order the
2747 records of equal priority (precedence). */
2751 GETSHORT(weight, s);
2755 /* Get the name of the host pointed to. */
2757 (void)dn_expand(dnsa.answer, dnsa.answer + dnsa.answerlen, s,
2758 (DN_EXPAND_ARG4_TYPE)data, sizeof(data));
2760 /* Check that we haven't already got this host on the chain; if we have,
2761 keep only the lower precedence. This situation shouldn't occur, but you
2762 never know what junk might get into the DNS (and this case has been seen on
2763 more than one occasion). */
2765 if (last != NULL) /* This is not the first record */
2767 host_item *prev = NULL;
2769 for (h = host; h != last->next; prev = h, h = h->next)
2771 if (strcmpic(h->name, data) == 0)
2773 DEBUG(D_host_lookup)
2774 debug_printf("discarded duplicate host %s (MX=%d)\n", data,
2775 (precedence > h->mx)? precedence : h->mx);
2776 if (precedence >= h->mx) goto NEXT_MX_RR; /* Skip greater precedence */
2777 if (h == host) /* Override first item */
2780 host->sort_key = precedence * 1000 + weight;
2784 /* Unwanted host item is not the first in the chain, so we can get
2785 get rid of it by cutting it out. */
2787 prev->next = h->next;
2788 if (h == last) last = prev;
2794 /* If this is the first MX or SRV record, put the data into the existing host
2795 block. Otherwise, add a new block in the correct place; if it has to be
2796 before the first block, copy the first block's data to a new second block. */
2800 host->name = string_copy_dnsdomain(data);
2801 host->address = NULL;
2803 host->mx = precedence;
2804 host->sort_key = precedence * 1000 + weight;
2805 host->status = hstatus_unknown;
2806 host->why = hwhy_unknown;
2807 host->dnssec = dnssec;
2811 /* Make a new host item and seek the correct insertion place */
2815 int sort_key = precedence * 1000 + weight;
2816 host_item *next = store_get(sizeof(host_item));
2817 next->name = string_copy_dnsdomain(data);
2818 next->address = NULL;
2820 next->mx = precedence;
2821 next->sort_key = sort_key;
2822 next->status = hstatus_unknown;
2823 next->why = hwhy_unknown;
2824 next->dnssec = dnssec;
2827 /* Handle the case when we have to insert before the first item. */
2829 if (sort_key < host->sort_key)
2836 if (last == host) last = next;
2839 /* Else scan down the items we have inserted as part of this exercise;
2840 don't go further. */
2844 for (h = host; h != last; h = h->next)
2846 if (sort_key < h->next->sort_key)
2848 next->next = h->next;
2854 /* Join on after the last host item that's part of this
2855 processing if we haven't stopped sooner. */
2859 next->next = last->next;
2866 NEXT_MX_RR: continue;
2869 /* If the list of hosts was obtained from SRV records, there are two things to
2870 do. First, if there is only one host, and it's name is ".", it means there is
2871 no SMTP service at this domain. Otherwise, we have to sort the hosts of equal
2872 priority according to their weights, using an algorithm that is defined in RFC
2873 2782. The hosts are currently sorted by priority and weight. For each priority
2874 group we have to pick off one host and put it first, and then repeat for any
2875 remaining in the same priority group. */
2877 if (ind_type == T_SRV)
2881 if (host == last && host->name[0] == 0)
2883 DEBUG(D_host_lookup) debug_printf("the single SRV record is \".\"\n");
2884 yield = HOST_FIND_FAILED;
2888 DEBUG(D_host_lookup)
2890 debug_printf("original ordering of hosts from SRV records:\n");
2891 for (h = host; h != last->next; h = h->next)
2892 debug_printf(" %s P=%d W=%d\n", h->name, h->mx, h->sort_key % 1000);
2895 for (pptr = &host, h = host; h != last; pptr = &(h->next), h = h->next)
2900 /* Find the last following host that has the same precedence. At the same
2901 time, compute the sum of the weights and the running totals. These can be
2902 stored in the sort_key field. */
2904 for (hh = h; hh != last; hh = hh->next)
2906 int weight = hh->sort_key % 1000; /* was precedence * 1000 + weight */
2909 if (hh->mx != hh->next->mx) break;
2912 /* If there's more than one host at this precedence (priority), we need to
2913 pick one to go first. */
2919 int randomizer = random_number(sum + 1);
2921 for (ppptr = pptr, hhh = h;
2923 ppptr = &(hhh->next), hhh = hhh->next)
2925 if (hhh->sort_key >= randomizer) break;
2928 /* hhh now points to the host that should go first; ppptr points to the
2929 place that points to it. Unfortunately, if the start of the minilist is
2930 the start of the entire list, we can't just swap the items over, because
2931 we must not change the value of host, since it is passed in from outside.
2932 One day, this could perhaps be changed.
2934 The special case is fudged by putting the new item *second* in the chain,
2935 and then transferring the data between the first and second items. We
2936 can't just swap the first and the chosen item, because that would mean
2937 that an item with zero weight might no longer be first. */
2941 *ppptr = hhh->next; /* Cuts it out of the chain */
2945 host_item temp = *h;
2948 hhh->next = temp.next;
2954 hhh->next = h; /* The rest of the chain follows it */
2955 *pptr = hhh; /* It takes the place of h */
2956 h = hhh; /* It's now the start of this minilist */
2961 /* A host has been chosen to be first at this priority and h now points
2962 to this host. There may be others at the same priority, or others at a
2963 different priority. Before we leave this host, we need to put back a sort
2964 key of the traditional MX kind, in case this host is multihomed, because
2965 the sort key is used for ordering the multiple IP addresses. We do not need
2966 to ensure that these new sort keys actually reflect the order of the hosts,
2969 h->sort_key = h->mx * 1000 + random_number(500);
2970 } /* Move on to the next host */
2973 /* Now we have to find IP addresses for all the hosts. We have ensured above
2974 that the names in all the host items are unique. Before release 4.61 we used to
2975 process records from the additional section in the DNS packet that returned the
2976 MX or SRV records. However, a DNS name server is free to drop any resource
2977 records from the additional section. In theory, this has always been a
2978 potential problem, but it is exacerbated by the advent of IPv6. If a host had
2979 several IPv4 addresses and some were not in the additional section, at least
2980 Exim would try the others. However, if a host had both IPv4 and IPv6 addresses
2981 and all the IPv4 (say) addresses were absent, Exim would try only for a IPv6
2982 connection, and never try an IPv4 address. When there was only IPv4
2983 connectivity, this was a disaster that did in practice occur.
2985 So, from release 4.61 onwards, we always search for A and AAAA records
2986 explicitly. The names shouldn't point to CNAMES, but we use the general lookup
2987 function that handles them, just in case. If any lookup gives a soft error,
2988 change the default yield.
2990 For these DNS lookups, we must disable qualify_single and search_parents;
2991 otherwise invalid host names obtained from MX or SRV records can cause trouble
2992 if they happen to match something local. */
2994 yield = HOST_FIND_FAILED; /* Default yield */
2995 dns_init(FALSE, FALSE, /* Disable qualify_single and search_parents */
2996 dnssec_request || dnssec_require);
2998 for (h = host; h != last->next; h = h->next)
3000 if (h->address != NULL) continue; /* Inserted by a multihomed host */
3001 rc = set_address_from_dns(h, &last, ignore_target_hosts, allow_mx_to_ip,
3002 NULL, dnssec_request, dnssec_require);
3003 if (rc != HOST_FOUND)
3005 h->status = hstatus_unusable;
3006 if (rc == HOST_FIND_AGAIN)
3009 h->why = hwhy_deferred;
3012 h->why = (rc == HOST_IGNORED)? hwhy_ignored : hwhy_failed;
3016 /* Scan the list for any hosts that are marked unusable because they have
3017 been explicitly ignored, and remove them from the list, as if they did not
3018 exist. If we end up with just a single, ignored host, flatten its fields as if
3019 nothing was found. */
3021 if (ignore_target_hosts != NULL)
3023 host_item *prev = NULL;
3024 for (h = host; h != last->next; h = h->next)
3027 if (h->why != hwhy_ignored) /* Non ignored host, just continue */
3029 else if (prev == NULL) /* First host is ignored */
3031 if (h != last) /* First is not last */
3033 if (h->next == last) last = h; /* Overwrite it with next */
3034 *h = *(h->next); /* and reprocess it. */
3035 goto REDO; /* C should have redo, like Perl */
3038 else /* Ignored host is not first - */
3040 prev->next = h->next;
3041 if (h == last) last = prev;
3045 if (host->why == hwhy_ignored) host->address = NULL;
3048 /* There is still one complication in the case of IPv6. Although the code above
3049 arranges that IPv6 addresses take precedence over IPv4 addresses for multihomed
3050 hosts, it doesn't do this for addresses that apply to different hosts with the
3051 same MX precedence, because the sorting on MX precedence happens first. So we
3052 have to make another pass to check for this case. We ensure that, within a
3053 single MX preference value, IPv6 addresses come first. This can separate the
3054 addresses of a multihomed host, but that should not matter. */
3057 if (h != last && !disable_ipv6)
3059 for (h = host; h != last; h = h->next)
3062 host_item *next = h->next;
3063 if (h->mx != next->mx || /* If next is different MX */
3064 h->address == NULL || /* OR this one is unset */
3065 Ustrchr(h->address, ':') != NULL || /* OR this one is IPv6 */
3066 (next->address != NULL &&
3067 Ustrchr(next->address, ':') == NULL)) /* OR next is IPv4 */
3068 continue; /* move on to next */
3069 temp = *h; /* otherwise, swap */
3070 temp.next = next->next;
3078 /* Remove any duplicate IP addresses and then scan the list of hosts for any
3079 whose IP addresses are on the local host. If any are found, all hosts with the
3080 same or higher MX values are removed. However, if the local host has the lowest
3081 numbered MX, then HOST_FOUND_LOCAL is returned. Otherwise, if at least one host
3082 with an IP address is on the list, HOST_FOUND is returned. Otherwise,
3083 HOST_FIND_FAILED is returned, but in this case do not update the yield, as it
3084 might have been set to HOST_FIND_AGAIN just above here. If not, it will already
3085 be HOST_FIND_FAILED. */
3087 host_remove_duplicates(host, &last);
3088 rc = host_scan_for_local_hosts(host, &last, removed);
3089 if (rc != HOST_FIND_FAILED) yield = rc;
3091 DEBUG(D_host_lookup)
3093 if (fully_qualified_name != NULL)
3094 debug_printf("fully qualified name = %s\n", *fully_qualified_name);
3095 debug_printf("host_find_bydns yield = %s (%d); returned hosts:\n",
3096 (yield == HOST_FOUND)? "HOST_FOUND" :
3097 (yield == HOST_FOUND_LOCAL)? "HOST_FOUND_LOCAL" :
3098 (yield == HOST_FIND_AGAIN)? "HOST_FIND_AGAIN" :
3099 (yield == HOST_FIND_FAILED)? "HOST_FIND_FAILED" : "?",
3101 for (h = host; h != last->next; h = h->next)
3103 debug_printf(" %s %s MX=%d %s", h->name,
3104 !h->address ? US"<null>" : h->address, h->mx,
3105 h->dnssec == DS_YES ? US"DNSSEC " : US"");
3106 if (h->port != PORT_NONE) debug_printf("port=%d ", h->port);
3107 if (h->status >= hstatus_unusable) debug_printf("*");
3114 dns_init(FALSE, FALSE, FALSE); /* clear the dnssec bit for getaddrbyname */
3118 /*************************************************
3119 **************************************************
3120 * Stand-alone test program *
3121 **************************************************
3122 *************************************************/
3126 int main(int argc, char **cargv)
3129 int whichrrs = HOST_FIND_BY_MX | HOST_FIND_BY_A;
3130 BOOL byname = FALSE;
3131 BOOL qualify_single = TRUE;
3132 BOOL search_parents = FALSE;
3133 BOOL request_dnssec = FALSE;
3134 BOOL require_dnssec = FALSE;
3135 uschar **argv = USS cargv;
3138 disable_ipv6 = FALSE;
3139 primary_hostname = US"";
3140 store_pool = POOL_MAIN;
3141 debug_selector = D_host_lookup|D_interface;
3142 debug_file = stdout;
3143 debug_fd = fileno(debug_file);
3145 printf("Exim stand-alone host functions test\n");
3147 host_find_interfaces();
3148 debug_selector = D_host_lookup | D_dns;
3150 if (argc > 1) primary_hostname = argv[1];
3152 /* So that debug level changes can be done first */
3154 dns_init(qualify_single, search_parents, FALSE);
3156 printf("Testing host lookup\n");
3158 while (Ufgets(buffer, 256, stdin) != NULL)
3161 int len = Ustrlen(buffer);
3162 uschar *fully_qualified_name;
3164 while (len > 0 && isspace(buffer[len-1])) len--;
3167 if (Ustrcmp(buffer, "q") == 0) break;
3169 if (Ustrcmp(buffer, "byname") == 0) byname = TRUE;
3170 else if (Ustrcmp(buffer, "no_byname") == 0) byname = FALSE;
3171 else if (Ustrcmp(buffer, "a_only") == 0) whichrrs = HOST_FIND_BY_A;
3172 else if (Ustrcmp(buffer, "mx_only") == 0) whichrrs = HOST_FIND_BY_MX;
3173 else if (Ustrcmp(buffer, "srv_only") == 0) whichrrs = HOST_FIND_BY_SRV;
3174 else if (Ustrcmp(buffer, "srv+a") == 0)
3175 whichrrs = HOST_FIND_BY_SRV | HOST_FIND_BY_A;
3176 else if (Ustrcmp(buffer, "srv+mx") == 0)
3177 whichrrs = HOST_FIND_BY_SRV | HOST_FIND_BY_MX;
3178 else if (Ustrcmp(buffer, "srv+mx+a") == 0)
3179 whichrrs = HOST_FIND_BY_SRV | HOST_FIND_BY_MX | HOST_FIND_BY_A;
3180 else if (Ustrcmp(buffer, "qualify_single") == 0) qualify_single = TRUE;
3181 else if (Ustrcmp(buffer, "no_qualify_single") == 0) qualify_single = FALSE;
3182 else if (Ustrcmp(buffer, "search_parents") == 0) search_parents = TRUE;
3183 else if (Ustrcmp(buffer, "no_search_parents") == 0) search_parents = FALSE;
3184 else if (Ustrcmp(buffer, "request_dnssec") == 0) request_dnssec = TRUE;
3185 else if (Ustrcmp(buffer, "no_request_dnssec") == 0) request_dnssec = FALSE;
3186 else if (Ustrcmp(buffer, "require_dnssec") == 0) require_dnssec = TRUE;
3187 else if (Ustrcmp(buffer, "no_reqiret_dnssec") == 0) require_dnssec = FALSE;
3188 else if (Ustrcmp(buffer, "test_harness") == 0)
3189 running_in_test_harness = !running_in_test_harness;
3190 else if (Ustrcmp(buffer, "ipv6") == 0) disable_ipv6 = !disable_ipv6;
3191 else if (Ustrcmp(buffer, "res_debug") == 0)
3193 _res.options ^= RES_DEBUG;
3195 else if (Ustrncmp(buffer, "retrans", 7) == 0)
3197 (void)sscanf(CS(buffer+8), "%d", &dns_retrans);
3198 _res.retrans = dns_retrans;
3200 else if (Ustrncmp(buffer, "retry", 5) == 0)
3202 (void)sscanf(CS(buffer+6), "%d", &dns_retry);
3203 _res.retry = dns_retry;
3207 int flags = whichrrs;
3213 h.status = hstatus_unknown;
3214 h.why = hwhy_unknown;
3217 if (qualify_single) flags |= HOST_FIND_QUALIFY_SINGLE;
3218 if (search_parents) flags |= HOST_FIND_SEARCH_PARENTS;
3221 ? host_find_byname(&h, NULL, flags, &fully_qualified_name, TRUE)
3222 : host_find_bydns(&h, NULL, flags, US"smtp", NULL, NULL,
3223 request_dnssec ? &h.name : NULL,
3224 require_dnssec ? &h.name : NULL,
3225 &fully_qualified_name, NULL);
3227 if (rc == HOST_FIND_FAILED) printf("Failed\n");
3228 else if (rc == HOST_FIND_AGAIN) printf("Again\n");
3229 else if (rc == HOST_FOUND_LOCAL) printf("Local\n");
3235 printf("Testing host_aton\n");
3237 while (Ufgets(buffer, 256, stdin) != NULL)
3241 int len = Ustrlen(buffer);
3243 while (len > 0 && isspace(buffer[len-1])) len--;
3246 if (Ustrcmp(buffer, "q") == 0) break;
3248 len = host_aton(buffer, x);
3249 printf("length = %d ", len);
3250 for (i = 0; i < len; i++)
3252 printf("%04x ", (x[i] >> 16) & 0xffff);
3253 printf("%04x ", x[i] & 0xffff);
3260 printf("Testing host_name_lookup\n");
3262 while (Ufgets(buffer, 256, stdin) != NULL)
3264 int len = Ustrlen(buffer);
3265 while (len > 0 && isspace(buffer[len-1])) len--;
3267 if (Ustrcmp(buffer, "q") == 0) break;
3268 sender_host_address = buffer;
3269 sender_host_name = NULL;
3270 sender_host_aliases = NULL;
3271 host_lookup_msg = US"";
3272 host_lookup_failed = FALSE;
3273 if (host_name_lookup() == FAIL) /* Debug causes printing */
3274 printf("Lookup failed:%s\n", host_lookup_msg);
3282 #endif /* STAND_ALONE */