1 /* $Cambridge: exim/src/src/host.c,v 1.1 2004/10/07 10:39:01 ph10 Exp $ */
3 /*************************************************
4 * Exim - an Internet mail transport agent *
5 *************************************************/
7 /* Copyright (c) University of Cambridge 1995 - 2004 */
8 /* See the file NOTICE for conditions of use and distribution. */
10 /* Functions for finding hosts, either by gethostbyname(), gethostbyaddr(), or
11 directly via the DNS. When IPv6 is supported, getipnodebyname() and
12 getipnodebyaddr() may be used instead of gethostbyname() and gethostbyaddr(),
13 if the newer functions are available. This module also contains various other
14 functions concerned with hosts and addresses, and a random number function,
15 used for randomizing hosts with equal MXs but available for use in other parts
22 /* Static variable for preserving the list of interface addresses in case it is
23 used more than once. */
25 static ip_address_item *local_interface_data = NULL;
28 #ifdef USE_INET_NTOA_FIX
29 /*************************************************
30 * Replacement for broken inet_ntoa() *
31 *************************************************/
33 /* On IRIX systems, gcc uses a different structure passing convention to the
34 native libraries. This causes inet_ntoa() to always yield 0.0.0.0 or
35 255.255.255.255. To get round this, we provide a private version of the
36 function here. It is used only if USE_INET_NTOA_FIX is set, which should happen
37 only when gcc is in use on an IRIX system. Code send to me by J.T. Breitner,
41 as seen in comp.sys.sgi.admin
43 Arguments: sa an in_addr structure
44 Returns: pointer to static text string
48 inet_ntoa(struct in_addr sa)
50 static uschar addr[20];
51 sprintf(addr, "%d.%d.%d.%d",
62 /*************************************************
63 * Random number generator *
64 *************************************************/
66 /* This is a simple pseudo-random number generator. It does not have to be
67 very good for the uses to which it is put. When running the regression tests,
68 start with a fixed seed.
71 limit: one more than the largest number required
73 Returns: a pseudo-random number in the range 0 to limit-1
77 random_number(int limit)
81 if (running_in_test_harness) random_seed = 42; else
83 int p = (int)getpid();
84 random_seed = (int)time(NULL) ^ ((p << 16) | p);
87 random_seed = 1103515245 * random_seed + 12345;
88 return (unsigned int)(random_seed >> 16) % limit;
93 /*************************************************
94 * Build chain of host items from list *
95 *************************************************/
97 /* This function builds a chain of host items from a textual list of host
98 names. It does not do any lookups. If randomize is true, the chain is build in
99 a randomized order. There may be multiple groups of independently randomized
100 hosts; they are delimited by a host name consisting of just "+".
103 anchor anchor for the chain
105 randomize TRUE for randomizing
111 host_build_hostlist(host_item **anchor, uschar *list, BOOL randomize)
114 int fake_mx = MX_NONE; /* This value is actually -1 */
118 if (list == NULL) return;
119 if (randomize) fake_mx--; /* Start at -2 for randomizing */
123 while ((name = string_nextinlist(&list, &sep, buffer, sizeof(buffer))) != NULL)
127 if (name[0] == '+' && name[1] == 0) /* "+" delimits a randomized group */
128 { /* ignore if not randomizing */
129 if (randomize) fake_mx--;
133 h = store_get(sizeof(host_item));
134 h->name = string_copy(name);
138 h->sort_key = randomize? (-fake_mx)*1000 + random_number(1000) : 0;
139 h->status = hstatus_unknown;
140 h->why = hwhy_unknown;
150 host_item *hh = *anchor;
151 if (h->sort_key < hh->sort_key)
158 while (hh->next != NULL && h->sort_key >= (hh->next)->sort_key)
171 /*************************************************
172 * Extract port from address string *
173 *************************************************/
175 /* In the spool file, and in the -oMa and -oMi options, a host plus port is
176 given as an IP address followed by a dot and a port number. This function
179 An alternative format for the -oMa and -oMi options is [ip address]:port which
180 is what Exim 4 uses for output, because it seems to becoming commonly used,
181 whereas the dot form confuses some programs/people. So we recognize that form
185 address points to the string; if there is a port, the '.' in the string
186 is overwritten with zero to terminate the address; if the string
187 is in the [xxx]:ppp format, the address is shifted left and the
190 Returns: 0 if there is no port, else the port number. If there's a syntax
191 error, leave the incoming address alone, and return 0.
195 host_extract_port(uschar *address)
200 /* Handle the "bracketed with colon on the end" format */
204 uschar *rb = address + 1;
205 while (*rb != 0 && *rb != ']') rb++;
206 if (*rb++ == 0) return 0; /* Missing ]; leave invalid address */
209 port = Ustrtol(rb + 1, &endptr, 10);
210 if (*endptr != 0) return 0; /* Invalid port; leave invalid address */
212 else if (*rb != 0) return 0; /* Bad syntax; leave invalid address */
213 memmove(address, address + 1, rb - address - 2);
217 /* Handle the "dot on the end" format */
221 int skip = -3; /* Skip 3 dots in IPv4 addresses */
223 while (*(++address) != 0)
226 if (ch == ':') skip = 0; /* Skip 0 dots in IPv6 addresses */
227 else if (ch == '.' && skip++ >= 0) break;
229 if (*address == 0) return 0;
230 port = Ustrtol(address + 1, &endptr, 10);
231 if (*endptr != 0) return 0; /* Invalid port; leave invalid address */
240 #ifndef STAND_ALONE /* Omit when standalone testing */
242 /*************************************************
243 * Build sender_fullhost and sender_rcvhost *
244 *************************************************/
246 /* This function is called when sender_host_name and/or sender_helo_name
247 have been set. Or might have been set - for a local message read off the spool
248 they won't be. In that case, do nothing. Otherwise, set up the fullhost string
251 (a) No sender_host_name or sender_helo_name: "[ip address]"
252 (b) Just sender_host_name: "host_name [ip address]"
253 (c) Just sender_helo_name: "(helo_name) [ip address]"
254 (d) The two are identical: "host_name [ip address]"
255 (e) The two are different: "host_name (helo_name) [ip address]"
257 If log_incoming_port is set, the sending host's port number is added to the IP
260 This function also builds sender_rcvhost for use in Received: lines, whose
261 syntax is a bit different. This value also includes the RFC 1413 identity.
262 There wouldn't be two different variables if I had got all this right in the
265 Because this data may survive over more than one incoming SMTP message, it has
266 to be in permanent store.
273 host_build_sender_fullhost(void)
276 int old_pool = store_pool;
278 if (sender_host_address == NULL) return;
280 store_pool = POOL_PERM;
282 /* Set up address, with or without the port. After discussion, it seems that
283 the only format that doesn't cause trouble is [aaaa]:pppp. However, we can't
284 use this directly as the first item for Received: because it ain't an RFC 2822
287 address = string_sprintf("[%s]:%d", sender_host_address, sender_host_port);
288 if ((log_extra_selector & LX_incoming_port) == 0 || sender_host_port <= 0)
289 *(Ustrrchr(address, ':')) = 0;
291 /* Host name is not verified */
293 if (sender_host_name == NULL)
295 uschar *portptr = Ustrstr(address, "]:");
298 int adlen; /* Sun compiler doesn't like ++ in initializers */
300 adlen = (portptr == NULL)? Ustrlen(address) : (++portptr - address);
301 sender_fullhost = (sender_helo_name == NULL)? address :
302 string_sprintf("(%s) %s", sender_helo_name, address);
304 sender_rcvhost = string_cat(NULL, &size, &ptr, address, adlen);
306 if (sender_ident != NULL || sender_helo_name != NULL || portptr != NULL)
309 sender_rcvhost = string_cat(sender_rcvhost, &size, &ptr, US" (", 2);
313 sender_rcvhost = string_append(sender_rcvhost, &size, &ptr, 2, US"port=",
316 if (sender_helo_name != NULL)
317 sender_rcvhost = string_append(sender_rcvhost, &size, &ptr, 2,
318 (firstptr == ptr)? US"helo=" : US" helo=", sender_helo_name);
320 if (sender_ident != NULL)
321 sender_rcvhost = string_append(sender_rcvhost, &size, &ptr, 2,
322 (firstptr == ptr)? US"ident=" : US" ident=", sender_ident);
324 sender_rcvhost = string_cat(sender_rcvhost, &size, &ptr, US")", 1);
327 sender_rcvhost[ptr] = 0; /* string_cat() always leaves room */
329 /* Release store, because string_cat allocated a minimum of 100 bytes that
330 are rarely completely used. */
332 store_reset(sender_rcvhost + ptr + 1);
335 /* Host name is known and verified. */
340 if (sender_helo_name == NULL ||
341 strcmpic(sender_host_name, sender_helo_name) == 0 ||
342 (sender_helo_name[0] == '[' &&
343 sender_helo_name[(len=Ustrlen(sender_helo_name))-1] == ']' &&
344 strncmpic(sender_helo_name+1, sender_host_address, len - 2) == 0))
346 sender_fullhost = string_sprintf("%s %s", sender_host_name, address);
347 sender_rcvhost = (sender_ident == NULL)?
348 string_sprintf("%s (%s)", sender_host_name, address) :
349 string_sprintf("%s (%s ident=%s)", sender_host_name, address,
354 sender_fullhost = string_sprintf("%s (%s) %s", sender_host_name,
355 sender_helo_name, address);
356 sender_rcvhost = (sender_ident == NULL)?
357 string_sprintf("%s (%s helo=%s)", sender_host_name,
358 address, sender_helo_name) :
359 string_sprintf("%s\n\t(%s helo=%s ident=%s)", sender_host_name,
360 address, sender_helo_name, sender_ident);
364 store_pool = old_pool;
366 DEBUG(D_host_lookup) debug_printf("sender_fullhost = %s\n", sender_fullhost);
367 DEBUG(D_host_lookup) debug_printf("sender_rcvhost = %s\n", sender_rcvhost);
372 /*************************************************
373 * Build host+ident message *
374 *************************************************/
376 /* Used when logging rejections and various ACL and SMTP incidents. The text
377 return depends on whether sender_fullhost and sender_ident are set or not:
379 no ident, no host => U=unknown
380 no ident, host set => H=sender_fullhost
381 ident set, no host => U=ident
382 ident set, host set => H=sender_fullhost U=ident
385 useflag TRUE if first item to be flagged (H= or U=); if there are two
386 items, the second is always flagged
388 Returns: pointer to a string in big_buffer
392 host_and_ident(BOOL useflag)
394 if (sender_fullhost == NULL)
396 (void)string_format(big_buffer, big_buffer_size, "%s%s", useflag? "U=" : "",
397 (sender_ident == NULL)? US"unknown" : sender_ident);
401 uschar *flag = useflag? US"H=" : US"";
402 uschar *iface = US"";
403 if ((log_extra_selector & LX_incoming_interface) != 0 &&
404 interface_address != NULL)
405 iface = string_sprintf(" I=[%s]:%d", interface_address, interface_port);
406 if (sender_ident == NULL)
407 (void)string_format(big_buffer, big_buffer_size, "%s%s%s",
408 flag, sender_fullhost, iface);
410 (void)string_format(big_buffer, big_buffer_size, "%s%s%s U=%s",
411 flag, sender_fullhost, iface, sender_ident);
416 #endif /* STAND_ALONE */
421 /*************************************************
422 * Build list of local interfaces *
423 *************************************************/
425 /* This function interprets the contents of the local_interfaces or
426 extra_local_interfaces options, and creates an ip_address_item block for each
427 item on the list. There is no special interpretation of any IP addresses; in
428 particular, 0.0.0.0 and ::0 are returned without modification. If any address
429 includes a port, it is set in the block. Otherwise the port value is set to
434 name the name of the option being expanded
436 Returns: a chain of ip_address_items, each containing to a textual
437 version of an IP address, and a port number (host order) or
438 zero if no port was given with the address
442 host_build_ifacelist(uschar *list, uschar *name)
447 ip_address_item *yield = NULL;
448 ip_address_item *last = NULL;
449 ip_address_item *next;
451 while ((s = string_nextinlist(&list, &sep, buffer, sizeof(buffer))) != NULL)
453 int port = host_extract_port(s); /* Leaves just the IP address */
454 if (!string_is_ip_address(s, NULL))
455 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "Malformed IP address \"%s\" in %s",
458 /* This use of strcpy() is OK because we have checked that s is a valid IP
459 address above. The field in the ip_address_item is large enough to hold an
462 next = store_get(sizeof(ip_address_item));
464 Ustrcpy(next->address, s);
466 next->v6_include_v4 = FALSE;
468 if (yield == NULL) yield = last = next; else
482 /*************************************************
483 * Find addresses on local interfaces *
484 *************************************************/
486 /* This function finds the addresses of local IP interfaces. These are used
487 when testing for routing to the local host. As the function may be called more
488 than once, the list is preserved in permanent store, pointed to by a static
489 variable, to save doing the work more than once per process.
491 The generic list of interfaces is obtained by calling host_build_ifacelist()
492 for local_interfaces and extra_local_interfaces. This list scanned to remove
493 duplicates (which may exist with different ports - not relevant here). If
494 either of the wildcard IP addresses (0.0.0.0 and ::0) are encountered, they are
495 replaced by the appropriate (IPv4 or IPv6) list of actual local interfaces,
496 obtained from os_find_running_interfaces().
499 Returns: a chain of ip_address_items, each containing to a textual
500 version of an IP address; the port numbers are not relevant
504 /* First, a local subfunction to add an interface to a list in permanent store,
505 but only if there isn't a previous copy of that address on the list. */
507 static ip_address_item *
508 add_unique_interface(ip_address_item *list, ip_address_item *ipa)
510 ip_address_item *ipa2;
511 for (ipa2 = list; ipa2 != NULL; ipa2 = ipa2->next)
512 if (Ustrcmp(ipa2->address, ipa->address) == 0) return list;
513 ipa2 = store_get_perm(sizeof(ip_address_item));
520 /* This is the globally visible function */
523 host_find_interfaces(void)
525 ip_address_item *running_interfaces = NULL;
527 if (local_interface_data == NULL)
529 void *reset_item = store_get(0);
530 ip_address_item *dlist = host_build_ifacelist(local_interfaces,
531 US"local_interfaces");
532 ip_address_item *xlist = host_build_ifacelist(extra_local_interfaces,
533 US"extra_local_interfaces");
534 ip_address_item *ipa;
536 if (dlist == NULL) dlist = xlist; else
538 for (ipa = dlist; ipa->next != NULL; ipa = ipa->next);
542 for (ipa = dlist; ipa != NULL; ipa = ipa->next)
544 if (Ustrcmp(ipa->address, "0.0.0.0") == 0 ||
545 Ustrcmp(ipa->address, "::0") == 0)
547 ip_address_item *ipa2;
548 BOOL ipv6 = ipa->address[0] == ':';
549 if (running_interfaces == NULL)
550 running_interfaces = os_find_running_interfaces();
551 for (ipa2 = running_interfaces; ipa2 != NULL; ipa2 = ipa2->next)
553 if ((Ustrchr(ipa2->address, ':') != NULL) == ipv6)
554 local_interface_data = add_unique_interface(local_interface_data,
560 local_interface_data = add_unique_interface(local_interface_data, ipa);
563 debug_printf("Configured local interface: address=%s", ipa->address);
564 if (ipa->port != 0) debug_printf(" port=%d", ipa->port);
569 store_reset(reset_item);
572 return local_interface_data;
579 /*************************************************
580 * Convert network IP address to text *
581 *************************************************/
583 /* Given an IPv4 or IPv6 address in binary, convert it to a text
584 string and return the result in a piece of new store. The address can
585 either be given directly, or passed over in a sockaddr structure. Note
586 that this isn't the converse of host_aton() because of byte ordering
587 differences. See host_nmtoa() below.
590 type if < 0 then arg points to a sockaddr, else
591 either AF_INET or AF_INET6
592 arg points to a sockaddr if type is < 0, or
593 points to an IPv4 address (32 bits), or
594 points to an IPv6 address (128 bits),
595 in both cases, in network byte order
596 buffer if NULL, the result is returned in gotten store;
597 else points to a buffer to hold the answer
598 portptr points to where to put the port number, if non NULL; only
601 Returns: pointer to character string
605 host_ntoa(int type, const void *arg, uschar *buffer, int *portptr)
609 /* The new world. It is annoying that we have to fish out the address from
610 different places in the block, depending on what kind of address it is. It
611 is also a pain that inet_ntop() returns a const uschar *, whereas the IPv4
612 function inet_ntoa() returns just uschar *, and some picky compilers insist
613 on warning if one assigns a const uschar * to a uschar *. Hence the casts. */
616 uschar addr_buffer[46];
619 int family = ((struct sockaddr *)arg)->sa_family;
620 if (family == AF_INET6)
622 struct sockaddr_in6 *sk = (struct sockaddr_in6 *)arg;
623 yield = (uschar *)inet_ntop(family, &(sk->sin6_addr), CS addr_buffer,
624 sizeof(addr_buffer));
625 if (portptr != NULL) *portptr = ntohs(sk->sin6_port);
629 struct sockaddr_in *sk = (struct sockaddr_in *)arg;
630 yield = (uschar *)inet_ntop(family, &(sk->sin_addr), CS addr_buffer,
631 sizeof(addr_buffer));
632 if (portptr != NULL) *portptr = ntohs(sk->sin_port);
637 yield = (uschar *)inet_ntop(type, arg, CS addr_buffer, sizeof(addr_buffer));
640 /* If the result is a mapped IPv4 address, show it in V4 format. */
642 if (Ustrncmp(yield, "::ffff:", 7) == 0) yield += 7;
644 #else /* HAVE_IPV6 */
650 yield = US inet_ntoa(((struct sockaddr_in *)arg)->sin_addr);
651 if (portptr != NULL) *portptr = ntohs(((struct sockaddr_in *)arg)->sin_port);
654 yield = US inet_ntoa(*((struct in_addr *)arg));
657 /* If there is no buffer, put the string into some new store. */
659 if (buffer == NULL) return string_copy(yield);
661 /* Callers of this function with a non-NULL buffer must ensure that it is
662 large enough to hold an IPv6 address, namely, at least 46 bytes. That's what
663 makes this use of strcpy() OK. */
665 Ustrcpy(buffer, yield);
672 /*************************************************
673 * Convert address text to binary *
674 *************************************************/
676 /* Given the textual form of an IP address, convert it to binary in an
677 array of ints. IPv4 addresses occupy one int; IPv6 addresses occupy 4 ints.
678 The result has the first byte in the most significant byte of the first int. In
679 other words, the result is not in network byte order, but in host byte order.
680 As a result, this is not the converse of host_ntoa(), which expects network
681 byte order. See host_nmtoa() below.
684 address points to the textual address, checked for syntax
685 bin points to an array of 4 ints
687 Returns: the number of ints used
691 host_aton(uschar *address, int *bin)
696 /* Handle IPv6 address, which may end with an IPv4 address. This code is NOT
697 enclosed in #if HAVE_IPV6 in order that IPv6 addresses are recognized even if
698 IPv6 is not supported. */
700 if (Ustrchr(address, ':') != NULL)
703 uschar *component[8];
704 BOOL ipv4_ends = FALSE;
710 /* If the address starts with a colon, it will start with two colons.
711 Just lose the first one, which will leave a null first component. */
715 /* Split the address into components separated by colons. */
719 int len = Ustrcspn(p, ":");
720 if (len == 0) nulloffset = ci;
726 /* If the final component contains a dot, it is a trailing v4 address.
727 As the syntax is known to be checked, just set up for a trailing
728 v4 address and restrict the v6 part to 6 components. */
730 if (Ustrchr(component[ci-1], '.') != NULL)
732 address = component[--ci];
738 /* If there are fewer than 6 or 8 components, we have to insert some
739 more empty ones in the middle. */
743 int insert_count = v6count - ci;
744 for (i = v6count-1; i > nulloffset + insert_count; i--)
745 component[i] = component[i - insert_count];
746 while (i > nulloffset) component[i--] = US"";
749 /* Now turn the components into binary in pairs and bung them
750 into the vector of ints. */
752 for (i = 0; i < v6count; i += 2)
753 bin[i/2] = (Ustrtol(component[i], NULL, 16) << 16) +
754 Ustrtol(component[i+1], NULL, 16);
756 /* If there was no terminating v4 component, we are done. */
758 if (!ipv4_ends) return 4;
761 /* Handle IPv4 address */
763 sscanf(CS address, "%d.%d.%d.%d", x, x+1, x+2, x+3);
764 bin[v4offset] = (x[0] << 24) + (x[1] << 16) + (x[2] << 8) + x[3];
769 /*************************************************
770 * Apply mask to an IP address *
771 *************************************************/
773 /* Mask an address held in 1 or 4 ints, with the ms bit in the ms bit of the
777 count the number of ints
778 binary points to the ints to be masked
779 mask the count of ms bits to leave, or -1 if no masking
785 host_mask(int count, int *binary, int mask)
788 if (mask < 0) mask = 99999;
789 for (i = 0; i < count; i++)
792 if (mask == 0) wordmask = 0;
795 wordmask = (-1) << (32 - mask);
803 binary[i] &= wordmask;
810 /*************************************************
811 * Convert masked IP address in ints to text *
812 *************************************************/
814 /* We can't use host_ntoa() because it assumes the binary values are in network
815 byte order, and these are the result of host_aton(), which puts them in ints in
816 host byte order. Also, we really want IPv6 addresses to be in a canonical
817 format, so we output them with no abbreviation. However, we can't use the
818 normal colon separator in them because it terminates keys in lsearch files, so
822 count 1 or 4 (number of ints)
823 binary points to the ints
824 mask mask value; if < 0 don't add to result
825 buffer big enough to hold the result
827 Returns: the number of characters placed in buffer, not counting
832 host_nmtoa(int count, int *binary, int mask, uschar *buffer)
840 for (i = 24; i >= 0; i -= 8)
842 sprintf(CS tt, "%d.", (j >> i) & 255);
848 for (i = 0; i < 4; i++)
851 sprintf(CS tt, "%04x.%04x.", (j >> 16) & 0xffff, j & 0xffff);
856 tt--; /* lose final . */
862 sprintf(CS tt, "/%d", mask);
871 /*************************************************
872 * Check port for tls_on_connect *
873 *************************************************/
875 /* This function checks whether a given incoming port is configured for tls-
876 on-connect. It is called from the daemon and from inetd handling. If the global
877 option tls_on_connect is already set, all ports operate this way. Otherwise, we
878 check the tls_on_connect_ports option for a list of ports.
880 Argument: a port number
881 Returns: TRUE or FALSE
885 host_is_tls_on_connect_port(int port)
889 uschar *list = tls_on_connect_ports;
892 if (tls_on_connect) return TRUE;
894 while ((s = string_nextinlist(&list, &sep, buffer, sizeof(buffer))) != NULL)
897 int lport = Ustrtol(s, &end, 10);
898 if (*end != 0) log_write(0, LOG_MAIN|LOG_PANIC_DIE, "tls_on_connect_ports "
899 "contains \"%s\", which is not a port number: exim abandoned", s);
900 if (lport == port) return TRUE;
908 /*************************************************
909 * Check whether host is in a network *
910 *************************************************/
912 /* This function checks whether a given IP address matches a pattern that
913 represents either a single host, or a network (using CIDR notation). The caller
914 of this function must check the syntax of the arguments before calling it.
917 host string representation of the ip-address to check
918 net string representation of the network, with optional CIDR mask
919 maskoffset offset to the / that introduces the mask in the key
920 zero if there is no mask
923 TRUE the host is inside the network
924 FALSE the host is NOT inside the network
928 host_is_in_net(uschar *host, uschar *net, int maskoffset)
934 int size = host_aton(net, address);
937 /* No mask => all bits to be checked */
939 if (maskoffset == 0) mlen = 99999; /* Big number */
940 else mlen = Uatoi(net + maskoffset + 1);
942 /* Convert the incoming address to binary. */
944 insize = host_aton(host, incoming);
946 /* Convert IPv4 addresses given in IPv6 compatible mode, which represent
947 connections from IPv4 hosts to IPv6 hosts, that is, addresses of the form
948 ::ffff:<v4address>, to IPv4 format. */
950 if (insize == 4 && incoming[0] == 0 && incoming[1] == 0 &&
951 incoming[2] == 0xffff)
954 incoming[0] = incoming[3];
957 /* No match if the sizes don't agree. */
959 if (insize != size) return FALSE;
961 /* Else do the masked comparison. */
963 for (i = 0; i < size; i++)
966 if (mlen == 0) mask = 0;
969 mask = (-1) << (32 - mlen);
977 if ((incoming[i] & mask) != (address[i] & mask)) return FALSE;
985 /*************************************************
986 * Scan host list for local hosts *
987 *************************************************/
989 /* Scan through a chain of addresses and check whether any of them is the
990 address of an interface on the local machine. If so, remove that address and
991 any previous ones with the same MX value, and all subsequent ones (which will
992 have greater or equal MX values) from the chain. Note: marking them as unusable
993 is NOT the right thing to do because it causes the hosts not to be used for
994 other domains, for which they may well be correct.
996 The hosts may be part of a longer chain; we only process those between the
997 initial pointer and the "last" pointer.
999 There is also a list of "pseudo-local" host names which are checked against the
1000 host names. Any match causes that host item to be treated the same as one which
1001 matches a local IP address.
1003 If the very first host is a local host, then all MX records had a precedence
1004 greater than or equal to that of the local host. Either there's a problem in
1005 the DNS, or an apparently remote name turned out to be an abbreviation for the
1006 local host. Give a specific return code, and let the caller decide what to do.
1007 Otherwise, give a success code if at least one host address has been found.
1010 host pointer to the first host in the chain
1011 lastptr pointer to pointer to the last host in the chain (may be updated)
1012 removed if not NULL, set TRUE if some local addresses were removed
1016 HOST_FOUND if there is at least one host with an IP address on the chain
1017 and an MX value less than any MX value associated with the
1019 HOST_FOUND_LOCAL if a local host is among the lowest-numbered MX hosts; when
1020 the host addresses were obtained from A records or
1021 gethostbyname(), the MX values are set to -1.
1022 HOST_FIND_FAILED if no valid hosts with set IP addresses were found
1026 host_scan_for_local_hosts(host_item *host, host_item **lastptr, BOOL *removed)
1028 int yield = HOST_FIND_FAILED;
1029 host_item *last = *lastptr;
1030 host_item *prev = NULL;
1033 if (removed != NULL) *removed = FALSE;
1035 if (local_interface_data == NULL) local_interface_data = host_find_interfaces();
1037 for (h = host; h != last->next; h = h->next)
1040 if (hosts_treat_as_local != NULL)
1043 uschar *save = deliver_domain;
1044 deliver_domain = h->name; /* set $domain */
1045 rc = match_isinlist(string_copylc(h->name), &hosts_treat_as_local, 0,
1046 &domainlist_anchor, NULL, MCL_DOMAIN, TRUE, NULL);
1047 deliver_domain = save;
1048 if (rc == OK) goto FOUND_LOCAL;
1052 /* It seems that on many operating systems, 0.0.0.0 is treated as a synonym
1053 for 127.0.0.1 and refers to the local host. We therefore force it always to
1054 be treated as local. */
1056 if (h->address != NULL)
1058 ip_address_item *ip;
1059 if (Ustrcmp(h->address, "0.0.0.0") == 0) goto FOUND_LOCAL;
1060 for (ip = local_interface_data; ip != NULL; ip = ip->next)
1061 if (Ustrcmp(h->address, ip->address) == 0) goto FOUND_LOCAL;
1062 yield = HOST_FOUND; /* At least one remote address has been found */
1065 /* Update prev to point to the last host item before any that have
1066 the same MX value as the one we have just considered. */
1068 if (h->next == NULL || h->next->mx != h->mx) prev = h;
1071 return yield; /* No local hosts found: return HOST_FOUND or HOST_FIND_FAILED */
1073 /* A host whose IP address matches a local IP address, or whose name matches
1074 something in hosts_treat_as_local has been found. */
1080 HDEBUG(D_host_lookup) debug_printf((h->mx >= 0)?
1081 "local host has lowest MX\n" :
1082 "local host found for non-MX address\n");
1083 return HOST_FOUND_LOCAL;
1086 HDEBUG(D_host_lookup)
1088 debug_printf("local host in host list - removed hosts:\n");
1089 for (h = prev->next; h != last->next; h = h->next)
1090 debug_printf(" %s %s %d\n", h->name, h->address, h->mx);
1093 if (removed != NULL) *removed = TRUE;
1094 prev->next = last->next;
1102 /*************************************************
1103 * Remove duplicate IPs in host list *
1104 *************************************************/
1106 /* You would think that administrators could set up their DNS records so that
1107 one ended up with a list of unique IP addresses after looking up A or MX
1108 records, but apparently duplication is common. So we scan such lists and
1109 remove the later duplicates. Note that we may get lists in which some host
1110 addresses are not set.
1113 host pointer to the first host in the chain
1114 lastptr pointer to pointer to the last host in the chain (may be updated)
1120 host_remove_duplicates(host_item *host, host_item **lastptr)
1122 while (host != *lastptr)
1124 if (host->address != NULL)
1126 host_item *h = host;
1127 while (h != *lastptr)
1129 if (h->next->address != NULL &&
1130 Ustrcmp(h->next->address, host->address) == 0)
1132 DEBUG(D_host_lookup) debug_printf("duplicate IP address %s (MX=%d) "
1133 "removed\n", host->address, h->next->mx);
1134 if (h->next == *lastptr) *lastptr = h;
1135 h->next = h->next->next;
1140 /* If the last item was removed, host may have become == *lastptr */
1141 if (host != *lastptr) host = host->next;
1148 /*************************************************
1149 * Find sender host name by gethostbyaddr() *
1150 *************************************************/
1152 /* This used to be the only way it was done, but it turns out that not all
1153 systems give aliases for calls to gethostbyaddr() - or one of the modern
1154 equivalents like getipnodebyaddr(). Fortunately, multiple PTR records are rare,
1155 but they can still exist. This function is now used only when a DNS lookup of
1156 the IP address fails, in order to give access to /etc/hosts.
1159 Returns: OK, DEFER, FAIL
1163 host_name_lookup_byaddr(void)
1167 struct hostent *hosts;
1168 struct in_addr addr;
1170 /* Lookup on IPv6 system */
1173 if (Ustrchr(sender_host_address, ':') != NULL)
1175 struct in6_addr addr6;
1176 if (inet_pton(AF_INET6, CS sender_host_address, &addr6) != 1)
1177 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "unable to parse \"%s\" as an "
1178 "IPv6 address", sender_host_address);
1179 #if HAVE_GETIPNODEBYADDR
1180 hosts = getipnodebyaddr(CS &addr6, sizeof(addr6), AF_INET6, &h_errno);
1182 hosts = gethostbyaddr(CS &addr6, sizeof(addr6), AF_INET6);
1187 if (inet_pton(AF_INET, CS sender_host_address, &addr) != 1)
1188 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "unable to parse \"%s\" as an "
1189 "IPv4 address", sender_host_address);
1190 #if HAVE_GETIPNODEBYADDR
1191 hosts = getipnodebyaddr(CS &addr, sizeof(addr), AF_INET, &h_errno);
1193 hosts = gethostbyaddr(CS &addr, sizeof(addr), AF_INET);
1197 /* Do lookup on IPv4 system */
1200 addr.s_addr = (S_ADDR_TYPE)inet_addr(CS sender_host_address);
1201 hosts = gethostbyaddr(CS(&addr), sizeof(addr), AF_INET);
1204 /* Failed to look up the host. */
1208 HDEBUG(D_host_lookup) debug_printf("IP address lookup failed: h_errno=%d\n",
1210 return (h_errno == TRY_AGAIN || h_errno == NO_RECOVERY) ? DEFER : FAIL;
1213 /* It seems there are some records in the DNS that yield an empty name. We
1214 treat this as non-existent. In some operating systems, this is returned as an
1215 empty string; in others as a single dot. */
1217 if (hosts->h_name[0] == 0 || hosts->h_name[0] == '.')
1219 HDEBUG(D_host_lookup) debug_printf("IP address lookup yielded an empty name: "
1220 "treated as non-existent host name\n");
1224 /* Copy and lowercase the name, which is in static storage in many systems.
1225 Put it in permanent memory. */
1227 s = (uschar *)hosts->h_name;
1228 len = Ustrlen(s) + 1;
1229 t = sender_host_name = store_get_perm(len);
1230 while (*s != 0) *t++ = tolower(*s++);
1233 /* If the host has aliases, build a copy of the alias list */
1235 if (hosts->h_aliases != NULL)
1238 uschar **aliases, **ptr;
1239 for (aliases = USS hosts->h_aliases; *aliases != NULL; aliases++) count++;
1240 ptr = sender_host_aliases = store_get_perm(count * sizeof(uschar *));
1241 for (aliases = USS hosts->h_aliases; *aliases != NULL; aliases++)
1243 uschar *s = *aliases;
1244 int len = Ustrlen(s) + 1;
1245 uschar *t = *ptr++ = store_get_perm(len);
1246 while (*s != 0) *t++ = tolower(*s++);
1257 /*************************************************
1258 * Find host name for incoming call *
1259 *************************************************/
1261 /* Put the name in permanent store, pointed to by sender_host_name. We also set
1262 up a list of alias names, pointed to by sender_host_alias. The list is
1263 NULL-terminated. The incoming address is in sender_host_address, either in
1264 dotted-quad form for IPv4 or in colon-separated form for IPv6.
1266 This function does a thorough check that the names it finds point back to the
1267 incoming IP address. Any that do not are discarded. Note that this is relied on
1268 by the ACL reverse_host_lookup check.
1270 On some systems, get{host,ipnode}byaddr() appears to do this internally, but
1271 this it not universally true. Also, for release 4.30, this function was changed
1272 to do a direct DNS lookup first, by default[1], because it turns out that that
1273 is the only guaranteed way to find all the aliases on some systems. My
1274 experiments indicate that Solaris gethostbyaddr() gives the aliases for but
1277 [1] The actual order is controlled by the host_lookup_order option.
1280 Returns: OK on success, the answer being placed in the global variable
1281 sender_host_name, with any aliases in a list hung off
1283 FAIL if no host name can be found
1284 DEFER if a temporary error was encountered
1286 The variable host_lookup_msg is set to an empty string on sucess, or to a
1287 reason for the failure otherwise, in a form suitable for tagging onto an error
1288 message, and also host_lookup_failed is set TRUE if the lookup failed. Any
1289 dynamically constructed string for host_lookup_msg must be in permanent store,
1290 because it might be used for several incoming messages on the same SMTP
1294 host_name_lookup(void)
1298 uschar *hname, *save_hostname;
1302 uschar *list = host_lookup_order;
1307 HDEBUG(D_host_lookup)
1308 debug_printf("looking up host name for %s\n", sender_host_address);
1310 /* For testing the case when a lookup does not complete, we have a special
1311 reserved IP address. */
1313 if (running_in_test_harness &&
1314 Ustrcmp(sender_host_address, "99.99.99.99") == 0)
1316 HDEBUG(D_host_lookup)
1317 debug_printf("Test harness: host name lookup returns DEFER\n");
1321 /* Do lookups directly in the DNS or via gethostbyaddr() (or equivalent), in
1322 the order specified by the host_lookup_order option. */
1324 while ((ordername = string_nextinlist(&list, &sep, buffer, sizeof(buffer)))
1327 if (strcmpic(ordername, US"bydns") == 0)
1329 dns_init(FALSE, FALSE);
1330 dns_build_reverse(sender_host_address, buffer);
1331 rc = dns_lookup(&dnsa, buffer, T_PTR, NULL);
1333 /* The first record we come across is used for the name; others are
1334 considered to be aliases. We have to scan twice, in order to find out the
1335 number of aliases. However, if all the names are empty, we will behave as
1336 if failure. (PTR records that yield empty names have been encountered in
1339 if (rc == DNS_SUCCEED)
1341 uschar **aptr = NULL;
1344 int old_pool = store_pool;
1346 store_pool = POOL_PERM; /* Save names in permanent storage */
1348 for (rr = dns_next_rr(&dnsa, &dnss, RESET_ANSWERS);
1350 rr = dns_next_rr(&dnsa, &dnss, RESET_NEXT))
1352 if (rr->type == T_PTR) count++;
1355 /* Get store for the list of aliases. For compatibility with
1356 gethostbyaddr, we make an empty list if there are none. */
1358 aptr = sender_host_aliases = store_get(count * sizeof(uschar *));
1360 /* Re-scan and extract the names */
1362 for (rr = dns_next_rr(&dnsa, &dnss, RESET_ANSWERS);
1364 rr = dns_next_rr(&dnsa, &dnss, RESET_NEXT))
1367 if (rr->type != T_PTR) continue;
1368 s = store_get(ssize);
1370 /* If an overlong response was received, the data will have been
1371 truncated and dn_expand may fail. */
1373 if (dn_expand(dnsa.answer, dnsa.answer + dnsa.answerlen,
1374 (uschar *)(rr->data), (DN_EXPAND_ARG4_TYPE)(s), ssize) < 0)
1376 log_write(0, LOG_MAIN, "host name alias list truncated for %s",
1377 sender_host_address);
1381 store_reset(s + Ustrlen(s) + 1);
1384 HDEBUG(D_host_lookup) debug_printf("IP address lookup yielded an "
1385 "empty name: treated as non-existent host name\n");
1388 if (sender_host_name == NULL) sender_host_name = s;
1390 while (*s != 0) { *s = tolower(*s); s++; }
1393 *aptr = NULL; /* End of alias list */
1394 store_pool = old_pool; /* Reset store pool */
1396 /* If we've found a names, break out of the "order" loop */
1398 if (sender_host_name != NULL) break;
1401 /* If the DNS lookup deferred, we must also defer. */
1403 if (rc == DNS_AGAIN)
1405 HDEBUG(D_host_lookup)
1406 debug_printf("IP address PTR lookup gave temporary error\n");
1411 /* Do a lookup using gethostbyaddr() - or equivalent */
1413 else if (strcmpic(ordername, US"byaddr") == 0)
1415 HDEBUG(D_host_lookup)
1416 debug_printf("IP address lookup using gethostbyaddr()\n");
1418 rc = host_name_lookup_byaddr();
1419 if (rc == DEFER) return rc; /* Can't carry on */
1420 if (rc == OK) break; /* Found a name */
1422 } /* Loop for bydns/byaddr scanning */
1424 /* If we have failed to find a name, return FAIL and log when required.
1425 NB host_lookup_msg must be in permanent store. */
1427 if (sender_host_name == NULL)
1429 if (host_checking || !log_testing_mode)
1430 log_write(L_host_lookup_failed, LOG_MAIN, "no host name found for IP "
1431 "address %s", sender_host_address);
1432 host_lookup_msg = US" (failed to find host name from IP address)";
1434 host_lookup_failed = TRUE;
1438 /* We have a host name. If we are running in the test harness, we want the host
1439 name and its alias to appear always the same way round. There are only ever two
1440 names in these tests. If one of them contains "alias", make sure it is second;
1441 otherwise put them in alphabetical order. */
1443 if (running_in_test_harness && *sender_host_aliases != NULL &&
1445 Ustrstr(sender_host_name, "alias") != NULL ||
1447 Ustrstr(*sender_host_aliases, "alias") == NULL &&
1448 Ustrcmp(sender_host_name, *sender_host_aliases) > 0
1452 uschar *temp = sender_host_name;
1453 sender_host_name = *sender_host_aliases;
1454 *sender_host_aliases = temp;
1457 /* Debug output what was found, after test harness swapping, for consistency */
1459 HDEBUG(D_host_lookup)
1461 uschar **aliases = sender_host_aliases;
1462 debug_printf("IP address lookup yielded %s\n", sender_host_name);
1463 while (*aliases != NULL) debug_printf(" alias %s\n", *aliases++);
1466 /* We need to verify that a forward lookup on the name we found does indeed
1467 correspond to the address. This is for security: in principle a malefactor who
1468 happened to own a reverse zone could set it to point to any names at all.
1470 This code was present in versions of Exim before 3.20. At that point I took it
1471 out because I thought that gethostbyaddr() did the check anyway. It turns out
1472 that this isn't always the case, so it's coming back in at 4.01. This version
1473 is actually better, because it also checks aliases.
1475 The code was made more robust at release 4.21. Prior to that, it accepted all
1476 the names if any of them had the correct IP address. Now the code checks all
1477 the names, and accepts only those that have the correct IP address. */
1479 save_hostname = sender_host_name; /* Save for error messages */
1480 aliases = sender_host_aliases;
1481 for (hname = sender_host_name; hname != NULL; hname = *aliases++)
1491 /* When called with the 5th argument FALSE, host_find_byname() won't return
1492 HOST_FOUND_LOCAL. If the incoming address is an IPv4 address expressed in
1493 IPv6 format, we must compare the IPv4 part to any IPv4 addresses. */
1495 if ((rc = host_find_byname(&h, NULL, NULL, FALSE)) == HOST_FOUND)
1498 uschar *address_ipv4 = (Ustrncmp(sender_host_address, "::ffff:", 7) == 0)?
1499 sender_host_address + 7 : sender_host_address;
1500 HDEBUG(D_host_lookup) debug_printf("checking addresses for %s\n", hname);
1501 for (hh = &h; hh != NULL; hh = hh->next)
1503 if ((Ustrcmp(hh->address, (Ustrchr(hh->address, ':') == NULL)?
1504 address_ipv4 : sender_host_address)) == 0)
1506 HDEBUG(D_host_lookup) debug_printf(" %s OK\n", hh->address);
1512 HDEBUG(D_host_lookup) debug_printf(" %s\n", hh->address);
1515 if (!ok) HDEBUG(D_host_lookup)
1516 debug_printf("no IP address for %s matched %s\n", hname,
1517 sender_host_address);
1519 else if (rc == HOST_FIND_AGAIN)
1521 HDEBUG(D_host_lookup) debug_printf("temporary error for host name lookup\n");
1526 HDEBUG(D_host_lookup) debug_printf("no IP addresses found for %s\n", hname);
1529 /* If this name is no good, and it's the sender name, set it null pro tem;
1530 if it's an alias, just remove it from the list. */
1534 if (hname == sender_host_name) sender_host_name = NULL; else
1536 uschar **a; /* Don't amalgamate - some */
1537 a = --aliases; /* compilers grumble */
1538 while (*a != NULL) { *a = a[1]; a++; }
1543 /* If sender_host_name == NULL, it means we didn't like the name. Replace
1544 it with the first alias, if there is one. */
1546 if (sender_host_name == NULL && *sender_host_aliases != NULL)
1547 sender_host_name = *sender_host_aliases++;
1549 /* If we now have a main name, all is well. */
1551 if (sender_host_name != NULL) return OK;
1553 /* We have failed to find an address that matches. */
1555 HDEBUG(D_host_lookup)
1556 debug_printf("%s does not match any IP address for %s\n",
1557 sender_host_address, save_hostname);
1559 /* This message must be in permanent store */
1561 old_pool = store_pool;
1562 store_pool = POOL_PERM;
1563 host_lookup_msg = string_sprintf(" (%s does not match any IP address for %s)",
1564 sender_host_address, save_hostname);
1565 store_pool = old_pool;
1567 host_lookup_failed = TRUE;
1574 /*************************************************
1575 * Find IP address(es) for host by name *
1576 *************************************************/
1578 /* The input is a host_item structure with the name filled in and the address
1579 field set to NULL. We use gethostbyname(). Of course, gethostbyname() may use
1580 the DNS, but it doesn't do MX processing. If more than one address is given,
1581 chain on additional host items, with other relevant fields copied.
1583 The second argument provides a host list (usually an IP list) of hosts to
1584 ignore. This makes it possible to ignore IPv6 link-local addresses or loopback
1585 addresses in unreasonable places.
1587 The lookup may result in a change of name. For compatibility with the dns
1588 lookup, return this via fully_qualified_name as well as updating the host item.
1589 The lookup may also yield more than one IP address, in which case chain on
1590 subsequent host_item structures.
1593 host a host item with the name and MX filled in;
1594 the address is to be filled in;
1595 multiple IP addresses cause other host items to be
1597 ignore_target_hosts a list of hosts to ignore
1598 fully_qualified_name if not NULL, set to point to host name for
1599 compatibility with host_find_bydns
1600 local_host_check TRUE if a check for the local host is wanted
1602 Returns: HOST_FIND_FAILED Failed to find the host or domain
1603 HOST_FIND_AGAIN Try again later
1604 HOST_FOUND Host found - data filled in
1605 HOST_FOUND_LOCAL Host found and is the local host
1609 host_find_byname(host_item *host, uschar *ignore_target_hosts,
1610 uschar **fully_qualified_name, BOOL local_host_check)
1612 int i, yield, times;
1614 host_item *last = NULL;
1615 BOOL temp_error = FALSE;
1617 /* In an IPv6 world, we need to scan for both kinds of address, so go round the
1618 loop twice. Note that we have ensured that AF_INET6 is defined even in an IPv4
1619 world, which makes for slightly tidier code. However, if dns_ipv4_lookup
1620 matches the domain, we also just do IPv4 lookups here (except when testing
1627 if (dns_ipv4_lookup != NULL &&
1628 match_isinlist(host->name, &dns_ipv4_lookup, 0, NULL, NULL, MCL_DOMAIN,
1630 { af = AF_INET; times = 1; }
1632 #endif /* STAND_ALONE */
1634 { af = AF_INET6; times = 2; }
1636 /* No IPv6 support */
1638 #else /* HAVE_IPV6 */
1640 #endif /* HAVE_IPV6 */
1642 /* Initialize the flag that gets set for DNS syntax check errors, so that the
1643 interface to this function can be similar to host_find_bydns. */
1645 host_find_failed_syntax = FALSE;
1647 /* Loop to look up both kinds of address in an IPv6 world */
1649 for (i = 1; i <= times;
1651 af = AF_INET, /* If 2 passes, IPv4 on the second */
1657 struct hostent *hostdata;
1660 #if HAVE_GETIPNODEBYNAME
1661 hostdata = getipnodebyname(CS host->name, af, 0, &error_num);
1663 hostdata = gethostbyname2(CS host->name, af);
1664 error_num = h_errno;
1667 hostdata = gethostbyname(CS host->name);
1668 error_num = h_errno;
1671 if (hostdata == NULL)
1676 case HOST_NOT_FOUND: error = US"HOST_NOT_FOUND"; break;
1677 case TRY_AGAIN: error = US"TRY_AGAIN"; break;
1678 case NO_RECOVERY: error = US"NO_RECOVERY"; break;
1679 case NO_DATA: error = US"NO_DATA"; break;
1680 #if NO_DATA != NO_ADDRESS
1681 case NO_ADDRESS: error = US"NO_ADDRESS"; break;
1683 default: error = US"?"; break;
1686 DEBUG(D_host_lookup) debug_printf("%s returned %d (%s)\n",
1688 #if HAVE_GETIPNODEBYNAME
1689 (af == AF_INET6)? "getipnodebyname(af=inet6)" : "getipnodebyname(af=inet)",
1691 (af == AF_INET6)? "gethostbyname2(af=inet6)" : "gethostbyname2(af=inet)",
1698 if (error_num == TRY_AGAIN || error_num == NO_RECOVERY) temp_error = TRUE;
1701 if ((hostdata->h_addr_list)[0] == NULL) continue;
1703 /* Replace the name with the fully qualified one if necessary, and fill in
1704 the fully_qualified_name pointer. */
1706 if (hostdata->h_name[0] != 0 &&
1707 Ustrcmp(host->name, hostdata->h_name) != 0)
1708 host->name = string_copy_dnsdomain((uschar *)hostdata->h_name);
1709 if (fully_qualified_name != NULL) *fully_qualified_name = host->name;
1711 /* Get the list of addresses. IPv4 and IPv6 addresses can be distinguished
1712 by their different lengths. Scan the list, ignoring any that are to be
1713 ignored, and build a chain from the rest. */
1715 ipv4_addr = hostdata->h_length == sizeof(struct in_addr);
1717 for (addrlist = USS hostdata->h_addr_list; *addrlist != NULL; addrlist++)
1719 uschar *text_address =
1720 host_ntoa(ipv4_addr? AF_INET:AF_INET6, *addrlist, NULL, NULL);
1723 if (ignore_target_hosts != NULL &&
1724 verify_check_this_host(&ignore_target_hosts, NULL, host->name,
1725 text_address, NULL) == OK)
1727 DEBUG(D_host_lookup)
1728 debug_printf("ignored host %s [%s]\n", host->name, text_address);
1733 /* If this is the first address, last == NULL and we put the data in the
1738 host->address = text_address;
1739 host->port = PORT_NONE;
1740 host->status = hstatus_unknown;
1741 host->why = hwhy_unknown;
1745 /* Else add further host item blocks for any other addresses, keeping
1750 host_item *next = store_get(sizeof(host_item));
1751 next->name = host->name;
1752 next->mx = host->mx;
1753 next->address = text_address;
1754 next->port = PORT_NONE;
1755 next->status = hstatus_unknown;
1756 next->why = hwhy_unknown;
1758 next->next = last->next;
1765 /* If no hosts were found, the address field in the original host block will be
1766 NULL. If temp_error is set, at least one of the lookups gave a temporary error,
1767 so we pass that back. */
1769 if (host->address == NULL)
1773 (message_id[0] == 0 && smtp_in != NULL)?
1774 string_sprintf("no IP address found for host %s (during %s)", host->name,
1775 smtp_get_connection_info()) :
1777 string_sprintf("no IP address found for host %s", host->name);
1779 HDEBUG(D_host_lookup) debug_printf("%s\n", msg);
1780 if (temp_error) return HOST_FIND_AGAIN;
1781 if (host_checking || !log_testing_mode)
1782 log_write(L_host_lookup_failed, LOG_MAIN, "%s", msg);
1783 return HOST_FIND_FAILED;
1786 /* Remove any duplicate IP addresses, then check to see if this is the local
1787 host if required. */
1789 host_remove_duplicates(host, &last);
1790 yield = local_host_check?
1791 host_scan_for_local_hosts(host, &last, NULL) : HOST_FOUND;
1793 /* When running in the test harness, sort into the order of addresses so as to
1794 get repeatability. This doesn't have to be efficient. But don't interchange
1795 IPv4 and IPv6 addresses! */
1797 if (running_in_test_harness)
1804 for (h = host; h != last; h = h->next)
1806 if ((Ustrchr(h->address, ':') == NULL) !=
1807 (Ustrchr(h->next->address, ':') == NULL))
1809 if (Ustrcmp(h->address, h->next->address) > 0)
1811 uschar *temp = h->address;
1812 h->address = h->next->address;
1813 h->next->address = temp;
1820 HDEBUG(D_host_lookup)
1823 if (fully_qualified_name != NULL)
1824 debug_printf("fully qualified name = %s\n", *fully_qualified_name);
1825 debug_printf("%s looked up these IP addresses:\n",
1827 #if HAVE_GETIPNODEBYNAME
1836 for (h = host; h != last->next; h = h->next)
1837 debug_printf(" name=%s address=%s\n", h->name,
1838 (h->address == NULL)? US"<null>" : h->address);
1841 /* Return the found status. */
1848 /*************************************************
1849 * Fill in a host address from the DNS *
1850 *************************************************/
1852 /* Given a host item, with its name and mx fields set, and its address field
1853 set to NULL, fill in its IP address from the DNS. If it is multi-homed, create
1854 additional host items for the additional addresses, copying all the other
1855 fields, and randomizing the order.
1857 On IPv6 systems, A6 records are sought first (but only if support for A6 is
1858 configured - they may never become mainstream), then AAAA records are sought,
1859 and finally A records are sought as well.
1861 The host name may be changed if the DNS returns a different name - e.g. fully
1862 qualified or changed via CNAME. If fully_qualified_name is not NULL, dns_lookup
1863 ensures that it points to the fully qualified name. However, this is the fully
1864 qualified version of the original name; if a CNAME is involved, the actual
1865 canonical host name may be different again, and so we get it directly from the
1866 relevant RR. Note that we do NOT change the mx field of the host item in this
1867 function as it may be called to set the addresses of hosts taken from MX
1871 host points to the host item we're filling in
1872 lastptr points to pointer to last host item in a chain of
1873 host items (may be updated if host is last and gets
1874 extended because multihomed)
1875 ignore_target_hosts list of hosts to ignore
1876 allow_ip if TRUE, recognize an IP address and return it
1877 fully_qualified_name if not NULL, return fully qualified name here if
1878 the contents are different (i.e. it must be preset
1881 Returns: HOST_FIND_FAILED couldn't find A record
1882 HOST_FIND_AGAIN try again later
1883 HOST_FOUND found AAAA and/or A record(s)
1884 HOST_IGNORED found, but all IPs ignored
1888 set_address_from_dns(host_item *host, host_item **lastptr,
1889 uschar *ignore_target_hosts, BOOL allow_ip, uschar **fully_qualified_name)
1892 host_item *thishostlast = NULL; /* Indicates not yet filled in anything */
1893 BOOL v6_find_again = FALSE;
1896 /* If allow_ip is set, a name which is an IP address returns that value
1897 as its address. This is used for MX records when allow_mx_to_ip is set, for
1898 those sites that feel they have to flaunt the RFC rules. */
1900 if (allow_ip && string_is_ip_address(host->name, NULL) != 0)
1903 if (ignore_target_hosts != NULL &&
1904 verify_check_this_host(&ignore_target_hosts, NULL, host->name,
1905 host->name, NULL) == OK)
1906 return HOST_IGNORED;
1909 host->address = host->name;
1910 host->port = PORT_NONE;
1914 /* On an IPv6 system, go round the loop up to three times, looking for A6 and
1915 AAAA records the first two times. However, unless doing standalone testing, we
1916 force an IPv4 lookup if the domain matches dns_ipv4_lookup is set. Since A6
1917 records look like being abandoned, support them only if explicitly configured
1918 to do so. On an IPv4 system, go round the loop once only, looking only for A
1924 if (dns_ipv4_lookup != NULL &&
1925 match_isinlist(host->name, &dns_ipv4_lookup, 0, NULL, NULL, MCL_DOMAIN,
1927 i = 0; /* look up A records only */
1929 #endif /* STAND_ALONE */
1932 i = 2; /* look up A6 and AAAA and A records */
1934 i = 1; /* look up AAAA and A records */
1935 #endif /* SUPPORT_A6 */
1937 /* The IPv4 world */
1939 #else /* HAVE_IPV6 */
1940 i = 0; /* look up A records only */
1941 #endif /* HAVE_IPV6 */
1945 static int types[] = { T_A, T_AAAA, T_A6 };
1946 int type = types[i];
1947 int randoffset = (i == 0)? 500 : 0; /* Ensures v6 sorts before v4 */
1951 int rc = dns_lookup(&dnsa, host->name, type, fully_qualified_name);
1953 /* We want to return HOST_FIND_AGAIN if one of the A, A6, or AAAA lookups
1954 fails or times out, but not if another one succeeds. (In the early
1955 IPv6 days there are name servers that always fail on AAAA, but are happy
1956 to give out an A record. We want to proceed with that A record.) */
1958 if (rc != DNS_SUCCEED)
1960 if (i == 0) /* Just tried for an A record, i.e. end of loop */
1962 if (host->address != NULL) return HOST_FOUND; /* A6 or AAAA was found */
1963 if (rc == DNS_AGAIN || rc == DNS_FAIL || v6_find_again)
1964 return HOST_FIND_AGAIN;
1965 return HOST_FIND_FAILED; /* DNS_NOMATCH or DNS_NODATA */
1968 /* Tried for an A6 or AAAA record: remember if this was a temporary
1969 error, and look for the next record type. */
1971 if (rc != DNS_NOMATCH && rc != DNS_NODATA) v6_find_again = TRUE;
1975 /* Lookup succeeded: fill in the given host item with the first non-ignored
1976 address found; create additional items for any others. A single A6 record
1977 may generate more than one address. */
1979 for (rr = dns_next_rr(&dnsa, &dnss, RESET_ANSWERS);
1981 rr = dns_next_rr(&dnsa, &dnss, RESET_NEXT))
1983 if (rr->type == type)
1985 /* dns_address *da = dns_address_from_rr(&dnsa, rr); */
1988 da = dns_address_from_rr(&dnsa, rr);
1990 DEBUG(D_host_lookup)
1993 debug_printf("no addresses extracted from A6 RR for %s\n",
1997 /* This loop runs only once for A and AAAA records, but may run
1998 several times for an A6 record that generated multiple addresses. */
2000 for (; da != NULL; da = da->next)
2003 if (ignore_target_hosts != NULL &&
2004 verify_check_this_host(&ignore_target_hosts, NULL,
2005 host->name, da->address, NULL) == OK)
2007 DEBUG(D_host_lookup)
2008 debug_printf("ignored host %s [%s]\n", host->name, da->address);
2013 /* If this is the first address, stick it in the given host block,
2014 and change the name if the returned RR has a different name. */
2016 if (thishostlast == NULL)
2018 if (strcmpic(host->name, rr->name) != 0)
2019 host->name = string_copy_dnsdomain(rr->name);
2020 host->address = da->address;
2021 host->port = PORT_NONE;
2022 host->sort_key = host->mx * 1000 + random_number(500) + randoffset;
2023 host->status = hstatus_unknown;
2024 host->why = hwhy_unknown;
2025 thishostlast = host;
2028 /* Not the first address. Check for, and ignore, duplicates. Then
2029 insert in the chain at a random point. */
2036 /* End of our local chain is specified by "thishostlast". */
2038 for (next = host;; next = next->next)
2040 if (Ustrcmp(CS da->address, next->address) == 0) break;
2041 if (next == thishostlast) { next = NULL; break; }
2043 if (next != NULL) continue; /* With loop for next address */
2045 /* Not a duplicate */
2047 new_sort_key = host->mx * 1000 + random_number(500) + randoffset;
2048 next = store_get(sizeof(host_item));
2050 /* New address goes first: insert the new block after the first one
2051 (so as not to disturb the original pointer) but put the new address
2052 in the original block. */
2054 if (new_sort_key < host->sort_key)
2058 host->address = da->address;
2059 host->port = PORT_NONE;
2060 host->sort_key = new_sort_key;
2061 if (thishostlast == host) thishostlast = next; /* Local last */
2062 if (*lastptr == host) *lastptr = next; /* Global last */
2065 /* Otherwise scan down the addresses for this host to find the
2066 one to insert after. */
2070 host_item *h = host;
2071 while (h != thishostlast)
2073 if (new_sort_key < h->next->sort_key) break;
2078 next->address = da->address;
2079 next->port = PORT_NONE;
2080 next->sort_key = new_sort_key;
2081 if (h == thishostlast) thishostlast = next; /* Local last */
2082 if (h == *lastptr) *lastptr = next; /* Global last */
2090 /* Control gets here only if the third lookup (the A record) succeeded.
2091 However, the address may not be filled in if it was ignored. */
2093 return (host->address == NULL)? HOST_IGNORED : HOST_FOUND;
2099 /*************************************************
2100 * Find IP addresses and names for host via DNS *
2101 *************************************************/
2103 /* The input is a host_item structure with the name filled in and the address
2104 field set to NULL. This may be in a chain of other host items. The lookup may
2105 result in more than one IP address, in which case we must created new host
2106 blocks for the additional addresses, and insert them into the chain. The
2107 original name may not be fully qualified. Use the fully_qualified_name argument
2108 to return the official name, as returned by the resolver.
2111 host point to initial host item
2112 ignore_target_hosts a list of hosts to ignore
2113 whichrrs flags indicating which RRs to look for:
2114 HOST_FIND_BY_SRV => look for SRV
2115 HOST_FIND_BY_MX => look for MX
2116 HOST_FIND_BY_A => look for A or AAAA
2117 also flags indicating how the lookup is done
2118 HOST_FIND_QUALIFY_SINGLE ) passed to the
2119 HOST_FIND_SEARCH_PARENTS ) resolver
2120 srv_service when SRV used, the service name
2121 srv_fail_domains DNS errors for these domains => assume nonexist
2122 mx_fail_domains DNS errors for these domains => assume nonexist
2123 fully_qualified_name if not NULL, return fully-qualified name
2124 removed set TRUE if local host was removed from the list
2126 Returns: HOST_FIND_FAILED Failed to find the host or domain;
2127 if there was a syntax error,
2128 host_find_failed_syntax is set.
2129 HOST_FIND_AGAIN Could not resolve at this time
2130 HOST_FOUND Host found
2131 HOST_FOUND_LOCAL The lowest MX record points to this
2132 machine, if MX records were found, or
2133 an A record that was found contains
2134 an address of the local host
2138 host_find_bydns(host_item *host, uschar *ignore_target_hosts, int whichrrs,
2139 uschar *srv_service, uschar *srv_fail_domains, uschar *mx_fail_domains,
2140 uschar **fully_qualified_name, BOOL *removed)
2142 host_item *h, *last;
2150 /* Set the default fully qualified name to the incoming name, initialize the
2151 resolver if necessary, set up the relevant options, and initialize the flag
2152 that gets set for DNS syntax check errors. */
2154 if (fully_qualified_name != NULL) *fully_qualified_name = host->name;
2155 dns_init((whichrrs & HOST_FIND_QUALIFY_SINGLE) != 0,
2156 (whichrrs & HOST_FIND_SEARCH_PARENTS) != 0);
2157 host_find_failed_syntax = FALSE;
2159 /* First, if requested, look for SRV records. The service name is given; we
2160 assume TCP progocol. DNS domain names are constrained to a maximum of 256
2161 characters, so the code below should be safe. */
2163 if ((whichrrs & HOST_FIND_BY_SRV) != 0)
2166 uschar *temp_fully_qualified_name = buffer;
2169 (void)sprintf(CS buffer, "_%s._tcp.%n%.256s", srv_service, &prefix_length,
2173 /* Search for SRV records. If the fully qualified name is different to
2174 the input name, pass back the new original domain, without the prepended
2177 rc = dns_lookup(&dnsa, buffer, ind_type, &temp_fully_qualified_name);
2178 if (temp_fully_qualified_name != buffer && fully_qualified_name != NULL)
2179 *fully_qualified_name = temp_fully_qualified_name + prefix_length;
2181 /* On DNS failures, we give the "try again" error unless the domain is
2182 listed as one for which we continue. */
2184 if (rc == DNS_FAIL || rc == DNS_AGAIN)
2186 if (match_isinlist(host->name, &srv_fail_domains, 0, NULL, NULL, MCL_DOMAIN,
2188 return HOST_FIND_AGAIN;
2189 DEBUG(D_host_lookup) debug_printf("DNS_%s treated as DNS_NODATA "
2190 "(domain in srv_fail_domains)\n", (rc == DNS_FAIL)? "FAIL":"AGAIN");
2194 /* If we did not find any SRV records, search the DNS for MX records, if
2195 requested to do so. If the result is DNS_NOMATCH, it means there is no such
2196 domain, and there's no point in going on to look for address records with the
2197 same domain. The result will be DNS_NODATA if the domain exists but has no MX
2198 records. On DNS failures, we give the "try again" error unless the domain is
2199 listed as one for which we continue. */
2201 if (rc != DNS_SUCCEED && (whichrrs & HOST_FIND_BY_MX) != 0)
2204 rc = dns_lookup(&dnsa, host->name, ind_type, fully_qualified_name);
2205 if (rc == DNS_NOMATCH) return HOST_FIND_FAILED;
2206 if (rc == DNS_FAIL || rc == DNS_AGAIN)
2208 if (match_isinlist(host->name, &mx_fail_domains, 0, NULL, NULL, MCL_DOMAIN,
2210 return HOST_FIND_AGAIN;
2211 DEBUG(D_host_lookup) debug_printf("DNS_%s treated as DNS_NODATA "
2212 "(domain in mx_fail_domains)\n", (rc == DNS_FAIL)? "FAIL":"AGAIN");
2216 /* If we haven't found anything yet, and we are requested to do so, try for an
2217 A or AAAA record. If we find it (or them) check to see that it isn't the local
2220 if (rc != DNS_SUCCEED)
2222 if ((whichrrs & HOST_FIND_BY_A) == 0)
2224 DEBUG(D_host_lookup) debug_printf("Address records are not being sought\n");
2225 return HOST_FIND_FAILED;
2228 last = host; /* End of local chainlet */
2230 host->port = PORT_NONE;
2231 rc = set_address_from_dns(host, &last, ignore_target_hosts, FALSE,
2232 fully_qualified_name);
2234 /* If one or more address records have been found, check that none of them
2235 are local. Since we know the host items all have their IP addresses
2236 inserted, host_scan_for_local_hosts() can only return HOST_FOUND or
2237 HOST_FOUND_LOCAL. We do not need to scan for duplicate IP addresses here,
2238 because set_address_from_dns() removes them. */
2240 if (rc == HOST_FOUND)
2241 rc = host_scan_for_local_hosts(host, &last, removed);
2243 if (rc == HOST_IGNORED) rc = HOST_FIND_FAILED; /* No special action */
2245 DEBUG(D_host_lookup)
2248 if (host->address != NULL)
2250 if (fully_qualified_name != NULL)
2251 debug_printf("fully qualified name = %s\n", *fully_qualified_name);
2252 for (h = host; h != last->next; h = h->next)
2253 debug_printf("%s %s mx=%d sort=%d %s\n", h->name,
2254 (h->address == NULL)? US"<null>" : h->address, h->mx, h->sort_key,
2255 (h->status >= hstatus_unusable)? US"*" : US"");
2262 /* We have found one or more MX or SRV records. Sort them according to
2263 precedence. Put the data for the first one into the existing host block, and
2264 insert new host_item blocks into the chain for the remainder. For equal
2265 precedences one is supposed to randomize the order. To make this happen, the
2266 sorting is actually done on the MX value * 1000 + a random number. This is put
2267 into a host field called sort_key.
2269 In the case of hosts with both IPv6 and IPv4 addresses, we want to choose the
2270 IPv6 address in preference. At this stage, we don't know what kind of address
2271 the host has. We choose a random number < 500; if later we find an A record
2272 first, we add 500 to the random number. Then for any other address records, we
2273 use random numbers in the range 0-499 for AAAA records and 500-999 for A
2276 At this point we remove any duplicates that point to the same host, retaining
2277 only the one with the lowest precedence. We cannot yet check for precedence
2278 greater than that of the local host, because that test cannot be properly done
2279 until the addresses have been found - an MX record may point to a name for this
2280 host which is not the primary hostname. */
2282 last = NULL; /* Indicates that not even the first item is filled yet */
2284 for (rr = dns_next_rr(&dnsa, &dnss, RESET_ANSWERS);
2286 rr = dns_next_rr(&dnsa, &dnss, RESET_NEXT))
2289 int weight = 0; /* For SRV records */
2290 int port = PORT_NONE; /* For SRV records */
2291 uschar *s; /* MUST be unsigned for GETSHORT */
2294 if (rr->type != ind_type) continue;
2296 GETSHORT(precedence, s); /* Pointer s is advanced */
2298 /* For MX records, we use a random "weight" which causes multiple records of
2299 the same precedence to sort randomly. */
2301 if (ind_type == T_MX)
2303 weight = random_number(500);
2306 /* SRV records are specified with a port and a weight. The weight is used
2307 in a special algorithm. However, to start with, we just use it to order the
2308 records of equal priority (precedence). */
2312 GETSHORT(weight, s);
2316 /* Get the name of the host pointed to. */
2318 (void)dn_expand(dnsa.answer, dnsa.answer + dnsa.answerlen, s,
2319 (DN_EXPAND_ARG4_TYPE)data, sizeof(data));
2321 /* Check that we haven't already got this host on the chain; if we have,
2322 keep only the lower precedence. This situation shouldn't occur, but you
2323 never know what junk might get into the DNS (and this case has been seen on
2324 more than one occasion). */
2326 if (last != NULL) /* This is not the first record */
2328 host_item *prev = NULL;
2330 for (h = host; h != last->next; prev = h, h = h->next)
2332 if (strcmpic(h->name, data) == 0)
2334 DEBUG(D_host_lookup)
2335 debug_printf("discarded duplicate host %s (MX=%d)\n", data,
2336 (precedence > h->mx)? precedence : h->mx);
2337 if (precedence >= h->mx) goto NEXT_MX_RR; /* Skip greater precedence */
2338 if (h == host) /* Override first item */
2341 host->sort_key = precedence * 1000 + weight;
2345 /* Unwanted host item is not the first in the chain, so we can get
2346 get rid of it by cutting it out. */
2348 prev->next = h->next;
2349 if (h == last) last = prev;
2355 /* If this is the first MX or SRV record, put the data into the existing host
2356 block. Otherwise, add a new block in the correct place; if it has to be
2357 before the first block, copy the first block's data to a new second block. */
2361 host->name = string_copy_dnsdomain(data);
2362 host->address = NULL;
2364 host->mx = precedence;
2365 host->sort_key = precedence * 1000 + weight;
2366 host->status = hstatus_unknown;
2367 host->why = hwhy_unknown;
2371 /* Make a new host item and seek the correct insertion place */
2375 int sort_key = precedence * 1000 + weight;
2376 host_item *next = store_get(sizeof(host_item));
2377 next->name = string_copy_dnsdomain(data);
2378 next->address = NULL;
2380 next->mx = precedence;
2381 next->sort_key = sort_key;
2382 next->status = hstatus_unknown;
2383 next->why = hwhy_unknown;
2386 /* Handle the case when we have to insert before the first item. */
2388 if (sort_key < host->sort_key)
2395 if (last == host) last = next;
2398 /* Else scan down the items we have inserted as part of this exercise;
2399 don't go further. */
2403 for (h = host; h != last; h = h->next)
2405 if (sort_key < h->next->sort_key)
2407 next->next = h->next;
2413 /* Join on after the last host item that's part of this
2414 processing if we haven't stopped sooner. */
2418 next->next = last->next;
2425 NEXT_MX_RR: continue;
2428 /* If the list of hosts was obtained from SRV records, there are two things to
2429 do. First, if there is only one host, and it's name is ".", it means there is
2430 no SMTP service at this domain. Otherwise, we have to sort the hosts of equal
2431 priority according to their weights, using an algorithm that is defined in RFC
2432 2782. The hosts are currently sorted by priority and weight. For each priority
2433 group we have to pick off one host and put it first, and then repeat for any
2434 remaining in the same priority group. */
2436 if (ind_type == T_SRV)
2440 if (host == last && host->name[0] == 0)
2442 DEBUG(D_host_lookup) debug_printf("the single SRV record is \".\"\n");
2443 return HOST_FIND_FAILED;
2446 DEBUG(D_host_lookup)
2448 debug_printf("original ordering of hosts from SRV records:\n");
2449 for (h = host; h != last->next; h = h->next)
2450 debug_printf(" %s P=%d W=%d\n", h->name, h->mx, h->sort_key % 1000);
2453 for (pptr = &host, h = host; h != last; pptr = &(h->next), h = h->next)
2458 /* Find the last following host that has the same precedence. At the same
2459 time, compute the sum of the weights and the running totals. These can be
2460 stored in the sort_key field. */
2462 for (hh = h; hh != last; hh = hh->next)
2464 int weight = hh->sort_key % 1000; /* was precedence * 1000 + weight */
2467 if (hh->mx != hh->next->mx) break;
2470 /* If there's more than one host at this precedence (priority), we need to
2471 pick one to go first. */
2477 int randomizer = random_number(sum + 1);
2479 for (ppptr = pptr, hhh = h;
2481 ppptr = &(hhh->next), hhh = hhh->next)
2483 if (hhh->sort_key >= randomizer) break;
2486 /* hhh now points to the host that should go first; ppptr points to the
2487 place that points to it. Unfortunately, if the start of the minilist is
2488 the start of the entire list, we can't just swap the items over, because
2489 we must not change the value of host, since it is passed in from outside.
2490 One day, this could perhaps be changed.
2492 The special case is fudged by putting the new item *second* in the chain,
2493 and then transferring the data between the first and second items. We
2494 can't just swap the first and the chosen item, because that would mean
2495 that an item with zero weight might no longer be first. */
2499 *ppptr = hhh->next; /* Cuts it out of the chain */
2503 host_item temp = *h;
2506 hhh->next = temp.next;
2512 hhh->next = h; /* The rest of the chain follows it */
2513 *pptr = hhh; /* It takes the place of h */
2514 h = hhh; /* It's now the start of this minilist */
2519 /* A host has been chosen to be first at this priority and h now points
2520 to this host. There may be others at the same priority, or others at a
2521 different priority. Before we leave this host, we need to put back a sort
2522 key of the traditional MX kind, in case this host is multihomed, because
2523 the sort key is used for ordering the multiple IP addresses. We do not need
2524 to ensure that these new sort keys actually reflect the order of the hosts,
2527 h->sort_key = h->mx * 1000 + random_number(500);
2528 } /* Move on to the next host */
2531 /* Now we have to ensure addresses exist for all the hosts. We have ensured
2532 above that the names in the host items are all unique. The addresses may have
2533 been returned in the additional data section of the DNS query. Because it is
2534 more expensive to scan the returned DNS records (because you have to expand the
2535 names) we do a single scan over them, and multiple scans of the chain of host
2536 items (which is typically only 3 or 4 long anyway.) Add extra host items for
2537 multi-homed hosts. */
2539 for (rr = dns_next_rr(&dnsa, &dnss, RESET_ADDITIONAL);
2541 rr = dns_next_rr(&dnsa, &dnss, RESET_NEXT))
2544 int status = hstatus_unknown;
2545 int why = hwhy_unknown;
2550 && rr->type != T_AAAA
2557 /* Find the first host that matches this record's name. If there isn't
2558 one, move on to the next RR. */
2560 for (h = host; h != last->next; h = h->next)
2561 { if (strcmpic(h->name, rr->name) == 0) break; }
2562 if (h == last->next) continue;
2564 /* For IPv4 addresses, add 500 to the random part of the sort key, to ensure
2565 they sort after IPv6 addresses. */
2567 randoffset = (rr->type == T_A)? 500 : 0;
2569 /* Get the list of textual addresses for this RR. There may be more than one
2570 if it is an A6 RR. Then loop to handle multiple addresses from an A6 record.
2571 If there are none, nothing will get done - the record is ignored. */
2573 for (da = dns_address_from_rr(&dnsa, rr); da != NULL; da = da->next)
2575 /* Set status for an ignorable host. */
2578 if (ignore_target_hosts != NULL &&
2579 verify_check_this_host(&ignore_target_hosts, NULL, h->name,
2580 da->address, NULL) == OK)
2582 DEBUG(D_host_lookup)
2583 debug_printf("ignored host %s [%s]\n", h->name, da->address);
2584 status = hstatus_unusable;
2589 /* If the address is already set for this host, it may be that
2590 we just have a duplicate DNS record. Alternatively, this may be
2591 a multi-homed host. Search all items with the same host name
2592 (they will all be together) and if this address is found, skip
2595 if (h->address != NULL)
2598 host_item *thishostlast;
2603 if (hh->address != NULL && Ustrcmp(CS da->address, hh->address) == 0)
2604 goto DNS_NEXT_RR; /* Need goto to escape from inner loop */
2608 while (hh != last->next && strcmpic(hh->name, rr->name) == 0);
2610 /* We have a multi-homed host, since we have a new address for
2611 an existing name. Create a copy of the current item, and give it
2612 the new address. RRs can be in arbitrary order, but one is supposed
2613 to randomize the addresses of multi-homed hosts, so compute a new
2614 sorting key and do that. [Latest SMTP RFC says not to randomize multi-
2615 homed hosts, but to rely on the resolver. I'm not happy about that -
2616 caching in the resolver will not rotate as often as the name server
2619 new_sort_key = h->mx * 1000 + random_number(500) + randoffset;
2620 hh = store_get(sizeof(host_item));
2622 /* New address goes first: insert the new block after the first one
2623 (so as not to disturb the original pointer) but put the new address
2624 in the original block. */
2626 if (new_sort_key < h->sort_key)
2628 *hh = *h; /* Note: copies the port */
2630 h->address = da->address;
2631 h->sort_key = new_sort_key;
2636 /* Otherwise scan down the addresses for this host to find the
2637 one to insert after. */
2641 while (h != thishostlast)
2643 if (new_sort_key < h->next->sort_key) break;
2646 *hh = *h; /* Note: copies the port */
2648 hh->address = da->address;
2649 hh->sort_key = new_sort_key;
2650 hh->status = status;
2654 if (h == last) last = hh; /* Inserted after last */
2657 /* The existing item doesn't have its address set yet, so just set it.
2658 Ensure that an IPv4 address gets its sort key incremented in case an IPv6
2659 address is found later. */
2663 h->address = da->address; /* Port should be set already */
2666 h->sort_key += randoffset;
2668 } /* Loop for addresses extracted from one RR */
2670 /* Carry on to the next RR. It would be nice to be able to be able to stop
2671 when every host on the list has an address, but we can't be sure there won't
2672 be an additional address for a multi-homed host further down the list, so
2673 we have to continue to the end. */
2675 DNS_NEXT_RR: continue;
2678 /* Set the default yield to failure */
2680 yield = HOST_FIND_FAILED;
2682 /* If we haven't found all the addresses in the additional section, we
2683 need to search for A or AAAA records explicitly. The names shouldn't point to
2684 CNAMES, but we use the general lookup function that handles them, just
2685 in case. If any lookup gives a soft error, change the default yield.
2687 For these DNS lookups, we must disable qualify_single and search_parents;
2688 otherwise invalid host names obtained from MX or SRV records can cause trouble
2689 if they happen to match something local. */
2691 dns_init(FALSE, FALSE);
2693 for (h = host; h != last->next; h = h->next)
2695 if (h->address != NULL || h->status == hstatus_unusable) continue;
2696 rc = set_address_from_dns(h, &last, ignore_target_hosts, allow_mx_to_ip, NULL);
2697 if (rc != HOST_FOUND)
2699 h->status = hstatus_unusable;
2700 if (rc == HOST_FIND_AGAIN)
2703 h->why = hwhy_deferred;
2706 h->why = (rc == HOST_IGNORED)? hwhy_ignored : hwhy_failed;
2710 /* Scan the list for any hosts that are marked unusable because they have
2711 been explicitly ignored, and remove them from the list, as if they did not
2712 exist. If we end up with just a single, ignored host, flatten its fields as if
2713 nothing was found. */
2715 if (ignore_target_hosts != NULL)
2717 host_item *prev = NULL;
2718 for (h = host; h != last->next; h = h->next)
2721 if (h->why != hwhy_ignored) /* Non ignored host, just continue */
2723 else if (prev == NULL) /* First host is ignored */
2725 if (h != last) /* First is not last */
2727 if (h->next == last) last = h; /* Overwrite it with next */
2728 *h = *(h->next); /* and reprocess it. */
2729 goto REDO; /* C should have redo, like Perl */
2732 else /* Ignored host is not first - */
2734 prev->next = h->next;
2735 if (h == last) last = prev;
2739 if (host->why == hwhy_ignored) host->address = NULL;
2742 /* There is still one complication in the case of IPv6. Although the code above
2743 arranges that IPv6 addresses take precedence over IPv4 addresses for multihomed
2744 hosts, it doesn't do this for addresses that apply to different hosts with the
2745 same MX precedence, because the sorting on MX precedence happens first. So we
2746 have to make another pass to check for this case. We ensure that, within a
2747 single MX preference value, IPv6 addresses come first. This can separate the
2748 addresses of a multihomed host, but that should not matter. */
2753 for (h = host; h != last; h = h->next)
2756 host_item *next = h->next;
2757 if (h->mx != next->mx || /* If next is different MX value */
2758 (h->sort_key % 1000) < 500 || /* OR this one is IPv6 */
2759 (next->sort_key % 1000) >= 500) /* OR next is IPv4 */
2760 continue; /* move on to next */
2762 temp.next = next->next;
2770 /* When running in the test harness, we want the hosts always to be in the same
2771 order so that the debugging output is the same and can be compared. Having a
2772 fixed set of "random" numbers doesn't actually achieve this, because the RRs
2773 come back from the resolver in a random order, so the non-random random numbers
2774 get used in a different order. We therefore have to sort the hosts that have
2775 the same MX values. We chose do to this by their name and then by IP address.
2776 The fact that the sort is slow matters not - this is testing only! */
2778 if (running_in_test_harness)
2784 for (h = host; h != last; h = h->next)
2786 int c = Ustrcmp(h->name, h->next->name);
2787 if (c == 0) c = Ustrcmp(h->address, h->next->address);
2788 if (h->mx == h->next->mx && c > 0)
2790 host_item *next = h->next;
2791 host_item temp = *h;
2792 temp.next = next->next;
2803 /* Remove any duplicate IP addresses and then scan the list of hosts for any
2804 whose IP addresses are on the local host. If any are found, all hosts with the
2805 same or higher MX values are removed. However, if the local host has the lowest
2806 numbered MX, then HOST_FOUND_LOCAL is returned. Otherwise, if at least one host
2807 with an IP address is on the list, HOST_FOUND is returned. Otherwise,
2808 HOST_FIND_FAILED is returned, but in this case do not update the yield, as it
2809 might have been set to HOST_FIND_AGAIN just above here. If not, it will already
2810 be HOST_FIND_FAILED. */
2812 host_remove_duplicates(host, &last);
2813 rc = host_scan_for_local_hosts(host, &last, removed);
2814 if (rc != HOST_FIND_FAILED) yield = rc;
2816 DEBUG(D_host_lookup)
2818 if (fully_qualified_name != NULL)
2819 debug_printf("fully qualified name = %s\n", *fully_qualified_name);
2820 debug_printf("host_find_bydns yield = %s (%d); returned hosts:\n",
2821 (yield == HOST_FOUND)? "HOST_FOUND" :
2822 (yield == HOST_FOUND_LOCAL)? "HOST_FOUND_LOCAL" :
2823 (yield == HOST_FIND_AGAIN)? "HOST_FIND_AGAIN" :
2824 (yield == HOST_FIND_FAILED)? "HOST_FIND_FAILED" : "?",
2826 for (h = host; h != last->next; h = h->next)
2828 debug_printf(" %s %s MX=%d ", h->name,
2829 (h->address == NULL)? US"<null>" : h->address, h->mx);
2830 if (h->port != PORT_NONE) debug_printf("port=%d ", h->port);
2831 if (h->status >= hstatus_unusable) debug_printf("*");
2842 /*************************************************
2843 **************************************************
2844 * Stand-alone test program *
2845 **************************************************
2846 *************************************************/
2850 BOOL alldigits(uschar *buffer)
2852 if (!isdigit(*buffer)) return FALSE;
2853 if (*buffer == '0' && buffer[1] == 'x')
2856 while (isxdigit(*(++buffer)));
2858 else while (isdigit(*(++buffer)));
2859 return (*buffer == 0);
2862 int main(int argc, char **cargv)
2865 int whichrrs = HOST_FIND_BY_MX | HOST_FIND_BY_A;
2866 BOOL byname = FALSE;
2867 BOOL qualify_single = TRUE;
2868 BOOL search_parents = FALSE;
2869 uschar **argv = USS cargv;
2872 primary_hostname = US"";
2873 store_pool = POOL_MAIN;
2874 debug_selector = D_host_lookup|D_interface;
2875 debug_file = stdout;
2876 debug_fd = fileno(debug_file);
2878 printf("Exim stand-alone host functions test\n");
2880 host_find_interfaces();
2881 debug_selector = D_host_lookup | D_dns;
2883 if (argc > 1) primary_hostname = argv[1];
2885 /* So that debug level changes can be done first */
2887 dns_init(qualify_single, search_parents);
2889 printf("Testing host lookup\n");
2891 while (Ufgets(buffer, 256, stdin) != NULL)
2894 int len = Ustrlen(buffer);
2895 uschar *fully_qualified_name;
2897 while (len > 0 && isspace(buffer[len-1])) len--;
2900 if (Ustrcmp(buffer, "q") == 0) break;
2902 if (Ustrcmp(buffer, "byname") == 0) byname = TRUE;
2903 else if (Ustrcmp(buffer, "no_byname") == 0) byname = FALSE;
2904 else if (Ustrcmp(buffer, "a_only") == 0) whichrrs = HOST_FIND_BY_A;
2905 else if (Ustrcmp(buffer, "mx_only") == 0) whichrrs = HOST_FIND_BY_MX;
2906 else if (Ustrcmp(buffer, "srv_only") == 0) whichrrs = HOST_FIND_BY_SRV;
2907 else if (Ustrcmp(buffer, "srv+a") == 0)
2908 whichrrs = HOST_FIND_BY_SRV | HOST_FIND_BY_A;
2909 else if (Ustrcmp(buffer, "srv+mx") == 0)
2910 whichrrs = HOST_FIND_BY_SRV | HOST_FIND_BY_MX;
2911 else if (Ustrcmp(buffer, "srv+mx+a") == 0)
2912 whichrrs = HOST_FIND_BY_SRV | HOST_FIND_BY_MX | HOST_FIND_BY_A;
2913 else if (Ustrcmp(buffer, "qualify_single") == 0) qualify_single = TRUE;
2914 else if (Ustrcmp(buffer, "no_qualify_single") == 0) qualify_single = FALSE;
2915 else if (Ustrcmp(buffer, "search_parents") == 0) search_parents = TRUE;
2916 else if (Ustrcmp(buffer, "no_search_parents") == 0) search_parents = FALSE;
2917 else if (Ustrncmp(buffer, "retrans", 7) == 0)
2919 sscanf(CS(buffer+8), "%d", &dns_retrans);
2920 _res.retrans = dns_retrans;
2922 else if (Ustrncmp(buffer, "retry", 5) == 0)
2924 sscanf(CS(buffer+6), "%d", &dns_retry);
2925 _res.retry = dns_retry;
2927 else if (alldigits(buffer))
2929 debug_selector = Ustrtol(buffer, NULL, 0);
2930 _res.options &= ~RES_DEBUG;
2931 DEBUG(D_resolver) _res.options |= RES_DEBUG;
2935 int flags = whichrrs;
2941 h.status = hstatus_unknown;
2942 h.why = hwhy_unknown;
2945 if (qualify_single) flags |= HOST_FIND_QUALIFY_SINGLE;
2946 if (search_parents) flags |= HOST_FIND_SEARCH_PARENTS;
2949 host_find_byname(&h, NULL, &fully_qualified_name, TRUE)
2951 host_find_bydns(&h, NULL, flags, US"smtp", NULL, NULL,
2952 &fully_qualified_name, NULL);
2954 if (rc == HOST_FIND_FAILED) printf("Failed\n");
2955 else if (rc == HOST_FIND_AGAIN) printf("Again\n");
2956 else if (rc == HOST_FOUND_LOCAL) printf("Local\n");
2962 printf("Testing host_aton\n");
2964 while (Ufgets(buffer, 256, stdin) != NULL)
2968 int len = Ustrlen(buffer);
2970 while (len > 0 && isspace(buffer[len-1])) len--;
2973 if (Ustrcmp(buffer, "q") == 0) break;
2975 len = host_aton(buffer, x);
2976 printf("length = %d ", len);
2977 for (i = 0; i < len; i++)
2979 printf("%04x ", (x[i] >> 16) & 0xffff);
2980 printf("%04x ", x[i] & 0xffff);
2987 printf("Testing host_name_lookup\n");
2989 while (Ufgets(buffer, 256, stdin) != NULL)
2991 int len = Ustrlen(buffer);
2992 while (len > 0 && isspace(buffer[len-1])) len--;
2994 if (Ustrcmp(buffer, "q") == 0) break;
2995 sender_host_address = buffer;
2996 sender_host_name = NULL;
2997 sender_host_aliases = NULL;
2998 host_lookup_msg = US"";
2999 host_lookup_failed = FALSE;
3000 if (host_name_lookup() == FAIL) /* Debug causes printing */
3001 printf("Lookup failed:%s\n", host_lookup_msg);
3009 #endif /* STAND_ALONE */