1 /* $Cambridge: exim/src/src/host.c,v 1.2 2004/11/12 16:54:55 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 * Sort addresses when testing *
95 *************************************************/
97 /* This function is called only when running in the test harness. It sorts a
98 number of multihomed host IP addresses into the order, so as to get
99 repeatability. This doesn't have to be efficient. But don't interchange IPv4
103 host -> the first host item
104 last -> the last host item
110 sort_addresses(host_item *host, host_item *last)
117 for (h = host; h != last; h = h->next)
119 if ((Ustrchr(h->address, ':') == NULL) !=
120 (Ustrchr(h->next->address, ':') == NULL))
122 if (Ustrcmp(h->address, h->next->address) > 0)
124 uschar *temp = h->address;
125 h->address = h->next->address;
126 h->next->address = temp;
135 /*************************************************
136 * Build chain of host items from list *
137 *************************************************/
139 /* This function builds a chain of host items from a textual list of host
140 names. It does not do any lookups. If randomize is true, the chain is build in
141 a randomized order. There may be multiple groups of independently randomized
142 hosts; they are delimited by a host name consisting of just "+".
145 anchor anchor for the chain
147 randomize TRUE for randomizing
153 host_build_hostlist(host_item **anchor, uschar *list, BOOL randomize)
156 int fake_mx = MX_NONE; /* This value is actually -1 */
160 if (list == NULL) return;
161 if (randomize) fake_mx--; /* Start at -2 for randomizing */
165 while ((name = string_nextinlist(&list, &sep, buffer, sizeof(buffer))) != NULL)
169 if (name[0] == '+' && name[1] == 0) /* "+" delimits a randomized group */
170 { /* ignore if not randomizing */
171 if (randomize) fake_mx--;
175 h = store_get(sizeof(host_item));
176 h->name = string_copy(name);
180 h->sort_key = randomize? (-fake_mx)*1000 + random_number(1000) : 0;
181 h->status = hstatus_unknown;
182 h->why = hwhy_unknown;
192 host_item *hh = *anchor;
193 if (h->sort_key < hh->sort_key)
200 while (hh->next != NULL && h->sort_key >= (hh->next)->sort_key)
213 /*************************************************
214 * Extract port from address string *
215 *************************************************/
217 /* In the spool file, and in the -oMa and -oMi options, a host plus port is
218 given as an IP address followed by a dot and a port number. This function
221 An alternative format for the -oMa and -oMi options is [ip address]:port which
222 is what Exim 4 uses for output, because it seems to becoming commonly used,
223 whereas the dot form confuses some programs/people. So we recognize that form
227 address points to the string; if there is a port, the '.' in the string
228 is overwritten with zero to terminate the address; if the string
229 is in the [xxx]:ppp format, the address is shifted left and the
232 Returns: 0 if there is no port, else the port number. If there's a syntax
233 error, leave the incoming address alone, and return 0.
237 host_extract_port(uschar *address)
242 /* Handle the "bracketed with colon on the end" format */
246 uschar *rb = address + 1;
247 while (*rb != 0 && *rb != ']') rb++;
248 if (*rb++ == 0) return 0; /* Missing ]; leave invalid address */
251 port = Ustrtol(rb + 1, &endptr, 10);
252 if (*endptr != 0) return 0; /* Invalid port; leave invalid address */
254 else if (*rb != 0) return 0; /* Bad syntax; leave invalid address */
255 memmove(address, address + 1, rb - address - 2);
259 /* Handle the "dot on the end" format */
263 int skip = -3; /* Skip 3 dots in IPv4 addresses */
265 while (*(++address) != 0)
268 if (ch == ':') skip = 0; /* Skip 0 dots in IPv6 addresses */
269 else if (ch == '.' && skip++ >= 0) break;
271 if (*address == 0) return 0;
272 port = Ustrtol(address + 1, &endptr, 10);
273 if (*endptr != 0) return 0; /* Invalid port; leave invalid address */
282 #ifndef STAND_ALONE /* Omit when standalone testing */
284 /*************************************************
285 * Build sender_fullhost and sender_rcvhost *
286 *************************************************/
288 /* This function is called when sender_host_name and/or sender_helo_name
289 have been set. Or might have been set - for a local message read off the spool
290 they won't be. In that case, do nothing. Otherwise, set up the fullhost string
293 (a) No sender_host_name or sender_helo_name: "[ip address]"
294 (b) Just sender_host_name: "host_name [ip address]"
295 (c) Just sender_helo_name: "(helo_name) [ip address]"
296 (d) The two are identical: "host_name [ip address]"
297 (e) The two are different: "host_name (helo_name) [ip address]"
299 If log_incoming_port is set, the sending host's port number is added to the IP
302 This function also builds sender_rcvhost for use in Received: lines, whose
303 syntax is a bit different. This value also includes the RFC 1413 identity.
304 There wouldn't be two different variables if I had got all this right in the
307 Because this data may survive over more than one incoming SMTP message, it has
308 to be in permanent store.
315 host_build_sender_fullhost(void)
318 int old_pool = store_pool;
320 if (sender_host_address == NULL) return;
322 store_pool = POOL_PERM;
324 /* Set up address, with or without the port. After discussion, it seems that
325 the only format that doesn't cause trouble is [aaaa]:pppp. However, we can't
326 use this directly as the first item for Received: because it ain't an RFC 2822
329 address = string_sprintf("[%s]:%d", sender_host_address, sender_host_port);
330 if ((log_extra_selector & LX_incoming_port) == 0 || sender_host_port <= 0)
331 *(Ustrrchr(address, ':')) = 0;
333 /* Host name is not verified */
335 if (sender_host_name == NULL)
337 uschar *portptr = Ustrstr(address, "]:");
340 int adlen; /* Sun compiler doesn't like ++ in initializers */
342 adlen = (portptr == NULL)? Ustrlen(address) : (++portptr - address);
343 sender_fullhost = (sender_helo_name == NULL)? address :
344 string_sprintf("(%s) %s", sender_helo_name, address);
346 sender_rcvhost = string_cat(NULL, &size, &ptr, address, adlen);
348 if (sender_ident != NULL || sender_helo_name != NULL || portptr != NULL)
351 sender_rcvhost = string_cat(sender_rcvhost, &size, &ptr, US" (", 2);
355 sender_rcvhost = string_append(sender_rcvhost, &size, &ptr, 2, US"port=",
358 if (sender_helo_name != NULL)
359 sender_rcvhost = string_append(sender_rcvhost, &size, &ptr, 2,
360 (firstptr == ptr)? US"helo=" : US" helo=", sender_helo_name);
362 if (sender_ident != NULL)
363 sender_rcvhost = string_append(sender_rcvhost, &size, &ptr, 2,
364 (firstptr == ptr)? US"ident=" : US" ident=", sender_ident);
366 sender_rcvhost = string_cat(sender_rcvhost, &size, &ptr, US")", 1);
369 sender_rcvhost[ptr] = 0; /* string_cat() always leaves room */
371 /* Release store, because string_cat allocated a minimum of 100 bytes that
372 are rarely completely used. */
374 store_reset(sender_rcvhost + ptr + 1);
377 /* Host name is known and verified. */
382 if (sender_helo_name == NULL ||
383 strcmpic(sender_host_name, sender_helo_name) == 0 ||
384 (sender_helo_name[0] == '[' &&
385 sender_helo_name[(len=Ustrlen(sender_helo_name))-1] == ']' &&
386 strncmpic(sender_helo_name+1, sender_host_address, len - 2) == 0))
388 sender_fullhost = string_sprintf("%s %s", sender_host_name, address);
389 sender_rcvhost = (sender_ident == NULL)?
390 string_sprintf("%s (%s)", sender_host_name, address) :
391 string_sprintf("%s (%s ident=%s)", sender_host_name, address,
396 sender_fullhost = string_sprintf("%s (%s) %s", sender_host_name,
397 sender_helo_name, address);
398 sender_rcvhost = (sender_ident == NULL)?
399 string_sprintf("%s (%s helo=%s)", sender_host_name,
400 address, sender_helo_name) :
401 string_sprintf("%s\n\t(%s helo=%s ident=%s)", sender_host_name,
402 address, sender_helo_name, sender_ident);
406 store_pool = old_pool;
408 DEBUG(D_host_lookup) debug_printf("sender_fullhost = %s\n", sender_fullhost);
409 DEBUG(D_host_lookup) debug_printf("sender_rcvhost = %s\n", sender_rcvhost);
414 /*************************************************
415 * Build host+ident message *
416 *************************************************/
418 /* Used when logging rejections and various ACL and SMTP incidents. The text
419 return depends on whether sender_fullhost and sender_ident are set or not:
421 no ident, no host => U=unknown
422 no ident, host set => H=sender_fullhost
423 ident set, no host => U=ident
424 ident set, host set => H=sender_fullhost U=ident
427 useflag TRUE if first item to be flagged (H= or U=); if there are two
428 items, the second is always flagged
430 Returns: pointer to a string in big_buffer
434 host_and_ident(BOOL useflag)
436 if (sender_fullhost == NULL)
438 (void)string_format(big_buffer, big_buffer_size, "%s%s", useflag? "U=" : "",
439 (sender_ident == NULL)? US"unknown" : sender_ident);
443 uschar *flag = useflag? US"H=" : US"";
444 uschar *iface = US"";
445 if ((log_extra_selector & LX_incoming_interface) != 0 &&
446 interface_address != NULL)
447 iface = string_sprintf(" I=[%s]:%d", interface_address, interface_port);
448 if (sender_ident == NULL)
449 (void)string_format(big_buffer, big_buffer_size, "%s%s%s",
450 flag, sender_fullhost, iface);
452 (void)string_format(big_buffer, big_buffer_size, "%s%s%s U=%s",
453 flag, sender_fullhost, iface, sender_ident);
458 #endif /* STAND_ALONE */
463 /*************************************************
464 * Build list of local interfaces *
465 *************************************************/
467 /* This function interprets the contents of the local_interfaces or
468 extra_local_interfaces options, and creates an ip_address_item block for each
469 item on the list. There is no special interpretation of any IP addresses; in
470 particular, 0.0.0.0 and ::0 are returned without modification. If any address
471 includes a port, it is set in the block. Otherwise the port value is set to
476 name the name of the option being expanded
478 Returns: a chain of ip_address_items, each containing to a textual
479 version of an IP address, and a port number (host order) or
480 zero if no port was given with the address
484 host_build_ifacelist(uschar *list, uschar *name)
489 ip_address_item *yield = NULL;
490 ip_address_item *last = NULL;
491 ip_address_item *next;
493 while ((s = string_nextinlist(&list, &sep, buffer, sizeof(buffer))) != NULL)
495 int port = host_extract_port(s); /* Leaves just the IP address */
496 if (!string_is_ip_address(s, NULL))
497 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "Malformed IP address \"%s\" in %s",
500 /* This use of strcpy() is OK because we have checked that s is a valid IP
501 address above. The field in the ip_address_item is large enough to hold an
504 next = store_get(sizeof(ip_address_item));
506 Ustrcpy(next->address, s);
508 next->v6_include_v4 = FALSE;
510 if (yield == NULL) yield = last = next; else
524 /*************************************************
525 * Find addresses on local interfaces *
526 *************************************************/
528 /* This function finds the addresses of local IP interfaces. These are used
529 when testing for routing to the local host. As the function may be called more
530 than once, the list is preserved in permanent store, pointed to by a static
531 variable, to save doing the work more than once per process.
533 The generic list of interfaces is obtained by calling host_build_ifacelist()
534 for local_interfaces and extra_local_interfaces. This list scanned to remove
535 duplicates (which may exist with different ports - not relevant here). If
536 either of the wildcard IP addresses (0.0.0.0 and ::0) are encountered, they are
537 replaced by the appropriate (IPv4 or IPv6) list of actual local interfaces,
538 obtained from os_find_running_interfaces().
541 Returns: a chain of ip_address_items, each containing to a textual
542 version of an IP address; the port numbers are not relevant
546 /* First, a local subfunction to add an interface to a list in permanent store,
547 but only if there isn't a previous copy of that address on the list. */
549 static ip_address_item *
550 add_unique_interface(ip_address_item *list, ip_address_item *ipa)
552 ip_address_item *ipa2;
553 for (ipa2 = list; ipa2 != NULL; ipa2 = ipa2->next)
554 if (Ustrcmp(ipa2->address, ipa->address) == 0) return list;
555 ipa2 = store_get_perm(sizeof(ip_address_item));
562 /* This is the globally visible function */
565 host_find_interfaces(void)
567 ip_address_item *running_interfaces = NULL;
569 if (local_interface_data == NULL)
571 void *reset_item = store_get(0);
572 ip_address_item *dlist = host_build_ifacelist(local_interfaces,
573 US"local_interfaces");
574 ip_address_item *xlist = host_build_ifacelist(extra_local_interfaces,
575 US"extra_local_interfaces");
576 ip_address_item *ipa;
578 if (dlist == NULL) dlist = xlist; else
580 for (ipa = dlist; ipa->next != NULL; ipa = ipa->next);
584 for (ipa = dlist; ipa != NULL; ipa = ipa->next)
586 if (Ustrcmp(ipa->address, "0.0.0.0") == 0 ||
587 Ustrcmp(ipa->address, "::0") == 0)
589 ip_address_item *ipa2;
590 BOOL ipv6 = ipa->address[0] == ':';
591 if (running_interfaces == NULL)
592 running_interfaces = os_find_running_interfaces();
593 for (ipa2 = running_interfaces; ipa2 != NULL; ipa2 = ipa2->next)
595 if ((Ustrchr(ipa2->address, ':') != NULL) == ipv6)
596 local_interface_data = add_unique_interface(local_interface_data,
602 local_interface_data = add_unique_interface(local_interface_data, ipa);
605 debug_printf("Configured local interface: address=%s", ipa->address);
606 if (ipa->port != 0) debug_printf(" port=%d", ipa->port);
611 store_reset(reset_item);
614 return local_interface_data;
621 /*************************************************
622 * Convert network IP address to text *
623 *************************************************/
625 /* Given an IPv4 or IPv6 address in binary, convert it to a text
626 string and return the result in a piece of new store. The address can
627 either be given directly, or passed over in a sockaddr structure. Note
628 that this isn't the converse of host_aton() because of byte ordering
629 differences. See host_nmtoa() below.
632 type if < 0 then arg points to a sockaddr, else
633 either AF_INET or AF_INET6
634 arg points to a sockaddr if type is < 0, or
635 points to an IPv4 address (32 bits), or
636 points to an IPv6 address (128 bits),
637 in both cases, in network byte order
638 buffer if NULL, the result is returned in gotten store;
639 else points to a buffer to hold the answer
640 portptr points to where to put the port number, if non NULL; only
643 Returns: pointer to character string
647 host_ntoa(int type, const void *arg, uschar *buffer, int *portptr)
651 /* The new world. It is annoying that we have to fish out the address from
652 different places in the block, depending on what kind of address it is. It
653 is also a pain that inet_ntop() returns a const uschar *, whereas the IPv4
654 function inet_ntoa() returns just uschar *, and some picky compilers insist
655 on warning if one assigns a const uschar * to a uschar *. Hence the casts. */
658 uschar addr_buffer[46];
661 int family = ((struct sockaddr *)arg)->sa_family;
662 if (family == AF_INET6)
664 struct sockaddr_in6 *sk = (struct sockaddr_in6 *)arg;
665 yield = (uschar *)inet_ntop(family, &(sk->sin6_addr), CS addr_buffer,
666 sizeof(addr_buffer));
667 if (portptr != NULL) *portptr = ntohs(sk->sin6_port);
671 struct sockaddr_in *sk = (struct sockaddr_in *)arg;
672 yield = (uschar *)inet_ntop(family, &(sk->sin_addr), CS addr_buffer,
673 sizeof(addr_buffer));
674 if (portptr != NULL) *portptr = ntohs(sk->sin_port);
679 yield = (uschar *)inet_ntop(type, arg, CS addr_buffer, sizeof(addr_buffer));
682 /* If the result is a mapped IPv4 address, show it in V4 format. */
684 if (Ustrncmp(yield, "::ffff:", 7) == 0) yield += 7;
686 #else /* HAVE_IPV6 */
692 yield = US inet_ntoa(((struct sockaddr_in *)arg)->sin_addr);
693 if (portptr != NULL) *portptr = ntohs(((struct sockaddr_in *)arg)->sin_port);
696 yield = US inet_ntoa(*((struct in_addr *)arg));
699 /* If there is no buffer, put the string into some new store. */
701 if (buffer == NULL) return string_copy(yield);
703 /* Callers of this function with a non-NULL buffer must ensure that it is
704 large enough to hold an IPv6 address, namely, at least 46 bytes. That's what
705 makes this use of strcpy() OK. */
707 Ustrcpy(buffer, yield);
714 /*************************************************
715 * Convert address text to binary *
716 *************************************************/
718 /* Given the textual form of an IP address, convert it to binary in an
719 array of ints. IPv4 addresses occupy one int; IPv6 addresses occupy 4 ints.
720 The result has the first byte in the most significant byte of the first int. In
721 other words, the result is not in network byte order, but in host byte order.
722 As a result, this is not the converse of host_ntoa(), which expects network
723 byte order. See host_nmtoa() below.
726 address points to the textual address, checked for syntax
727 bin points to an array of 4 ints
729 Returns: the number of ints used
733 host_aton(uschar *address, int *bin)
738 /* Handle IPv6 address, which may end with an IPv4 address. This code is NOT
739 enclosed in #if HAVE_IPV6 in order that IPv6 addresses are recognized even if
740 IPv6 is not supported. */
742 if (Ustrchr(address, ':') != NULL)
745 uschar *component[8];
746 BOOL ipv4_ends = FALSE;
752 /* If the address starts with a colon, it will start with two colons.
753 Just lose the first one, which will leave a null first component. */
757 /* Split the address into components separated by colons. */
761 int len = Ustrcspn(p, ":");
762 if (len == 0) nulloffset = ci;
768 /* If the final component contains a dot, it is a trailing v4 address.
769 As the syntax is known to be checked, just set up for a trailing
770 v4 address and restrict the v6 part to 6 components. */
772 if (Ustrchr(component[ci-1], '.') != NULL)
774 address = component[--ci];
780 /* If there are fewer than 6 or 8 components, we have to insert some
781 more empty ones in the middle. */
785 int insert_count = v6count - ci;
786 for (i = v6count-1; i > nulloffset + insert_count; i--)
787 component[i] = component[i - insert_count];
788 while (i > nulloffset) component[i--] = US"";
791 /* Now turn the components into binary in pairs and bung them
792 into the vector of ints. */
794 for (i = 0; i < v6count; i += 2)
795 bin[i/2] = (Ustrtol(component[i], NULL, 16) << 16) +
796 Ustrtol(component[i+1], NULL, 16);
798 /* If there was no terminating v4 component, we are done. */
800 if (!ipv4_ends) return 4;
803 /* Handle IPv4 address */
805 sscanf(CS address, "%d.%d.%d.%d", x, x+1, x+2, x+3);
806 bin[v4offset] = (x[0] << 24) + (x[1] << 16) + (x[2] << 8) + x[3];
811 /*************************************************
812 * Apply mask to an IP address *
813 *************************************************/
815 /* Mask an address held in 1 or 4 ints, with the ms bit in the ms bit of the
819 count the number of ints
820 binary points to the ints to be masked
821 mask the count of ms bits to leave, or -1 if no masking
827 host_mask(int count, int *binary, int mask)
830 if (mask < 0) mask = 99999;
831 for (i = 0; i < count; i++)
834 if (mask == 0) wordmask = 0;
837 wordmask = (-1) << (32 - mask);
845 binary[i] &= wordmask;
852 /*************************************************
853 * Convert masked IP address in ints to text *
854 *************************************************/
856 /* We can't use host_ntoa() because it assumes the binary values are in network
857 byte order, and these are the result of host_aton(), which puts them in ints in
858 host byte order. Also, we really want IPv6 addresses to be in a canonical
859 format, so we output them with no abbreviation. However, we can't use the
860 normal colon separator in them because it terminates keys in lsearch files, so
864 count 1 or 4 (number of ints)
865 binary points to the ints
866 mask mask value; if < 0 don't add to result
867 buffer big enough to hold the result
869 Returns: the number of characters placed in buffer, not counting
874 host_nmtoa(int count, int *binary, int mask, uschar *buffer)
882 for (i = 24; i >= 0; i -= 8)
884 sprintf(CS tt, "%d.", (j >> i) & 255);
890 for (i = 0; i < 4; i++)
893 sprintf(CS tt, "%04x.%04x.", (j >> 16) & 0xffff, j & 0xffff);
898 tt--; /* lose final . */
904 sprintf(CS tt, "/%d", mask);
913 /*************************************************
914 * Check port for tls_on_connect *
915 *************************************************/
917 /* This function checks whether a given incoming port is configured for tls-
918 on-connect. It is called from the daemon and from inetd handling. If the global
919 option tls_on_connect is already set, all ports operate this way. Otherwise, we
920 check the tls_on_connect_ports option for a list of ports.
922 Argument: a port number
923 Returns: TRUE or FALSE
927 host_is_tls_on_connect_port(int port)
931 uschar *list = tls_on_connect_ports;
934 if (tls_on_connect) return TRUE;
936 while ((s = string_nextinlist(&list, &sep, buffer, sizeof(buffer))) != NULL)
939 int lport = Ustrtol(s, &end, 10);
940 if (*end != 0) log_write(0, LOG_MAIN|LOG_PANIC_DIE, "tls_on_connect_ports "
941 "contains \"%s\", which is not a port number: exim abandoned", s);
942 if (lport == port) return TRUE;
950 /*************************************************
951 * Check whether host is in a network *
952 *************************************************/
954 /* This function checks whether a given IP address matches a pattern that
955 represents either a single host, or a network (using CIDR notation). The caller
956 of this function must check the syntax of the arguments before calling it.
959 host string representation of the ip-address to check
960 net string representation of the network, with optional CIDR mask
961 maskoffset offset to the / that introduces the mask in the key
962 zero if there is no mask
965 TRUE the host is inside the network
966 FALSE the host is NOT inside the network
970 host_is_in_net(uschar *host, uschar *net, int maskoffset)
976 int size = host_aton(net, address);
979 /* No mask => all bits to be checked */
981 if (maskoffset == 0) mlen = 99999; /* Big number */
982 else mlen = Uatoi(net + maskoffset + 1);
984 /* Convert the incoming address to binary. */
986 insize = host_aton(host, incoming);
988 /* Convert IPv4 addresses given in IPv6 compatible mode, which represent
989 connections from IPv4 hosts to IPv6 hosts, that is, addresses of the form
990 ::ffff:<v4address>, to IPv4 format. */
992 if (insize == 4 && incoming[0] == 0 && incoming[1] == 0 &&
993 incoming[2] == 0xffff)
996 incoming[0] = incoming[3];
999 /* No match if the sizes don't agree. */
1001 if (insize != size) return FALSE;
1003 /* Else do the masked comparison. */
1005 for (i = 0; i < size; i++)
1008 if (mlen == 0) mask = 0;
1011 mask = (-1) << (32 - mlen);
1019 if ((incoming[i] & mask) != (address[i] & mask)) return FALSE;
1027 /*************************************************
1028 * Scan host list for local hosts *
1029 *************************************************/
1031 /* Scan through a chain of addresses and check whether any of them is the
1032 address of an interface on the local machine. If so, remove that address and
1033 any previous ones with the same MX value, and all subsequent ones (which will
1034 have greater or equal MX values) from the chain. Note: marking them as unusable
1035 is NOT the right thing to do because it causes the hosts not to be used for
1036 other domains, for which they may well be correct.
1038 The hosts may be part of a longer chain; we only process those between the
1039 initial pointer and the "last" pointer.
1041 There is also a list of "pseudo-local" host names which are checked against the
1042 host names. Any match causes that host item to be treated the same as one which
1043 matches a local IP address.
1045 If the very first host is a local host, then all MX records had a precedence
1046 greater than or equal to that of the local host. Either there's a problem in
1047 the DNS, or an apparently remote name turned out to be an abbreviation for the
1048 local host. Give a specific return code, and let the caller decide what to do.
1049 Otherwise, give a success code if at least one host address has been found.
1052 host pointer to the first host in the chain
1053 lastptr pointer to pointer to the last host in the chain (may be updated)
1054 removed if not NULL, set TRUE if some local addresses were removed
1058 HOST_FOUND if there is at least one host with an IP address on the chain
1059 and an MX value less than any MX value associated with the
1061 HOST_FOUND_LOCAL if a local host is among the lowest-numbered MX hosts; when
1062 the host addresses were obtained from A records or
1063 gethostbyname(), the MX values are set to -1.
1064 HOST_FIND_FAILED if no valid hosts with set IP addresses were found
1068 host_scan_for_local_hosts(host_item *host, host_item **lastptr, BOOL *removed)
1070 int yield = HOST_FIND_FAILED;
1071 host_item *last = *lastptr;
1072 host_item *prev = NULL;
1075 if (removed != NULL) *removed = FALSE;
1077 if (local_interface_data == NULL) local_interface_data = host_find_interfaces();
1079 for (h = host; h != last->next; h = h->next)
1082 if (hosts_treat_as_local != NULL)
1085 uschar *save = deliver_domain;
1086 deliver_domain = h->name; /* set $domain */
1087 rc = match_isinlist(string_copylc(h->name), &hosts_treat_as_local, 0,
1088 &domainlist_anchor, NULL, MCL_DOMAIN, TRUE, NULL);
1089 deliver_domain = save;
1090 if (rc == OK) goto FOUND_LOCAL;
1094 /* It seems that on many operating systems, 0.0.0.0 is treated as a synonym
1095 for 127.0.0.1 and refers to the local host. We therefore force it always to
1096 be treated as local. */
1098 if (h->address != NULL)
1100 ip_address_item *ip;
1101 if (Ustrcmp(h->address, "0.0.0.0") == 0) goto FOUND_LOCAL;
1102 for (ip = local_interface_data; ip != NULL; ip = ip->next)
1103 if (Ustrcmp(h->address, ip->address) == 0) goto FOUND_LOCAL;
1104 yield = HOST_FOUND; /* At least one remote address has been found */
1107 /* Update prev to point to the last host item before any that have
1108 the same MX value as the one we have just considered. */
1110 if (h->next == NULL || h->next->mx != h->mx) prev = h;
1113 return yield; /* No local hosts found: return HOST_FOUND or HOST_FIND_FAILED */
1115 /* A host whose IP address matches a local IP address, or whose name matches
1116 something in hosts_treat_as_local has been found. */
1122 HDEBUG(D_host_lookup) debug_printf((h->mx >= 0)?
1123 "local host has lowest MX\n" :
1124 "local host found for non-MX address\n");
1125 return HOST_FOUND_LOCAL;
1128 HDEBUG(D_host_lookup)
1130 debug_printf("local host in host list - removed hosts:\n");
1131 for (h = prev->next; h != last->next; h = h->next)
1132 debug_printf(" %s %s %d\n", h->name, h->address, h->mx);
1135 if (removed != NULL) *removed = TRUE;
1136 prev->next = last->next;
1144 /*************************************************
1145 * Remove duplicate IPs in host list *
1146 *************************************************/
1148 /* You would think that administrators could set up their DNS records so that
1149 one ended up with a list of unique IP addresses after looking up A or MX
1150 records, but apparently duplication is common. So we scan such lists and
1151 remove the later duplicates. Note that we may get lists in which some host
1152 addresses are not set.
1155 host pointer to the first host in the chain
1156 lastptr pointer to pointer to the last host in the chain (may be updated)
1162 host_remove_duplicates(host_item *host, host_item **lastptr)
1164 while (host != *lastptr)
1166 if (host->address != NULL)
1168 host_item *h = host;
1169 while (h != *lastptr)
1171 if (h->next->address != NULL &&
1172 Ustrcmp(h->next->address, host->address) == 0)
1174 DEBUG(D_host_lookup) debug_printf("duplicate IP address %s (MX=%d) "
1175 "removed\n", host->address, h->next->mx);
1176 if (h->next == *lastptr) *lastptr = h;
1177 h->next = h->next->next;
1182 /* If the last item was removed, host may have become == *lastptr */
1183 if (host != *lastptr) host = host->next;
1190 /*************************************************
1191 * Find sender host name by gethostbyaddr() *
1192 *************************************************/
1194 /* This used to be the only way it was done, but it turns out that not all
1195 systems give aliases for calls to gethostbyaddr() - or one of the modern
1196 equivalents like getipnodebyaddr(). Fortunately, multiple PTR records are rare,
1197 but they can still exist. This function is now used only when a DNS lookup of
1198 the IP address fails, in order to give access to /etc/hosts.
1201 Returns: OK, DEFER, FAIL
1205 host_name_lookup_byaddr(void)
1209 struct hostent *hosts;
1210 struct in_addr addr;
1212 /* Lookup on IPv6 system */
1215 if (Ustrchr(sender_host_address, ':') != NULL)
1217 struct in6_addr addr6;
1218 if (inet_pton(AF_INET6, CS sender_host_address, &addr6) != 1)
1219 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "unable to parse \"%s\" as an "
1220 "IPv6 address", sender_host_address);
1221 #if HAVE_GETIPNODEBYADDR
1222 hosts = getipnodebyaddr(CS &addr6, sizeof(addr6), AF_INET6, &h_errno);
1224 hosts = gethostbyaddr(CS &addr6, sizeof(addr6), AF_INET6);
1229 if (inet_pton(AF_INET, CS sender_host_address, &addr) != 1)
1230 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "unable to parse \"%s\" as an "
1231 "IPv4 address", sender_host_address);
1232 #if HAVE_GETIPNODEBYADDR
1233 hosts = getipnodebyaddr(CS &addr, sizeof(addr), AF_INET, &h_errno);
1235 hosts = gethostbyaddr(CS &addr, sizeof(addr), AF_INET);
1239 /* Do lookup on IPv4 system */
1242 addr.s_addr = (S_ADDR_TYPE)inet_addr(CS sender_host_address);
1243 hosts = gethostbyaddr(CS(&addr), sizeof(addr), AF_INET);
1246 /* Failed to look up the host. */
1250 HDEBUG(D_host_lookup) debug_printf("IP address lookup failed: h_errno=%d\n",
1252 return (h_errno == TRY_AGAIN || h_errno == NO_RECOVERY) ? DEFER : FAIL;
1255 /* It seems there are some records in the DNS that yield an empty name. We
1256 treat this as non-existent. In some operating systems, this is returned as an
1257 empty string; in others as a single dot. */
1259 if (hosts->h_name[0] == 0 || hosts->h_name[0] == '.')
1261 HDEBUG(D_host_lookup) debug_printf("IP address lookup yielded an empty name: "
1262 "treated as non-existent host name\n");
1266 /* Copy and lowercase the name, which is in static storage in many systems.
1267 Put it in permanent memory. */
1269 s = (uschar *)hosts->h_name;
1270 len = Ustrlen(s) + 1;
1271 t = sender_host_name = store_get_perm(len);
1272 while (*s != 0) *t++ = tolower(*s++);
1275 /* If the host has aliases, build a copy of the alias list */
1277 if (hosts->h_aliases != NULL)
1280 uschar **aliases, **ptr;
1281 for (aliases = USS hosts->h_aliases; *aliases != NULL; aliases++) count++;
1282 ptr = sender_host_aliases = store_get_perm(count * sizeof(uschar *));
1283 for (aliases = USS hosts->h_aliases; *aliases != NULL; aliases++)
1285 uschar *s = *aliases;
1286 int len = Ustrlen(s) + 1;
1287 uschar *t = *ptr++ = store_get_perm(len);
1288 while (*s != 0) *t++ = tolower(*s++);
1299 /*************************************************
1300 * Find host name for incoming call *
1301 *************************************************/
1303 /* Put the name in permanent store, pointed to by sender_host_name. We also set
1304 up a list of alias names, pointed to by sender_host_alias. The list is
1305 NULL-terminated. The incoming address is in sender_host_address, either in
1306 dotted-quad form for IPv4 or in colon-separated form for IPv6.
1308 This function does a thorough check that the names it finds point back to the
1309 incoming IP address. Any that do not are discarded. Note that this is relied on
1310 by the ACL reverse_host_lookup check.
1312 On some systems, get{host,ipnode}byaddr() appears to do this internally, but
1313 this it not universally true. Also, for release 4.30, this function was changed
1314 to do a direct DNS lookup first, by default[1], because it turns out that that
1315 is the only guaranteed way to find all the aliases on some systems. My
1316 experiments indicate that Solaris gethostbyaddr() gives the aliases for but
1319 [1] The actual order is controlled by the host_lookup_order option.
1322 Returns: OK on success, the answer being placed in the global variable
1323 sender_host_name, with any aliases in a list hung off
1325 FAIL if no host name can be found
1326 DEFER if a temporary error was encountered
1328 The variable host_lookup_msg is set to an empty string on sucess, or to a
1329 reason for the failure otherwise, in a form suitable for tagging onto an error
1330 message, and also host_lookup_failed is set TRUE if the lookup failed. Any
1331 dynamically constructed string for host_lookup_msg must be in permanent store,
1332 because it might be used for several incoming messages on the same SMTP
1336 host_name_lookup(void)
1340 uschar *hname, *save_hostname;
1344 uschar *list = host_lookup_order;
1349 HDEBUG(D_host_lookup)
1350 debug_printf("looking up host name for %s\n", sender_host_address);
1352 /* For testing the case when a lookup does not complete, we have a special
1353 reserved IP address. */
1355 if (running_in_test_harness &&
1356 Ustrcmp(sender_host_address, "99.99.99.99") == 0)
1358 HDEBUG(D_host_lookup)
1359 debug_printf("Test harness: host name lookup returns DEFER\n");
1363 /* Do lookups directly in the DNS or via gethostbyaddr() (or equivalent), in
1364 the order specified by the host_lookup_order option. */
1366 while ((ordername = string_nextinlist(&list, &sep, buffer, sizeof(buffer)))
1369 if (strcmpic(ordername, US"bydns") == 0)
1371 dns_init(FALSE, FALSE);
1372 dns_build_reverse(sender_host_address, buffer);
1373 rc = dns_lookup(&dnsa, buffer, T_PTR, NULL);
1375 /* The first record we come across is used for the name; others are
1376 considered to be aliases. We have to scan twice, in order to find out the
1377 number of aliases. However, if all the names are empty, we will behave as
1378 if failure. (PTR records that yield empty names have been encountered in
1381 if (rc == DNS_SUCCEED)
1383 uschar **aptr = NULL;
1386 int old_pool = store_pool;
1388 store_pool = POOL_PERM; /* Save names in permanent storage */
1390 for (rr = dns_next_rr(&dnsa, &dnss, RESET_ANSWERS);
1392 rr = dns_next_rr(&dnsa, &dnss, RESET_NEXT))
1394 if (rr->type == T_PTR) count++;
1397 /* Get store for the list of aliases. For compatibility with
1398 gethostbyaddr, we make an empty list if there are none. */
1400 aptr = sender_host_aliases = store_get(count * sizeof(uschar *));
1402 /* Re-scan and extract the names */
1404 for (rr = dns_next_rr(&dnsa, &dnss, RESET_ANSWERS);
1406 rr = dns_next_rr(&dnsa, &dnss, RESET_NEXT))
1409 if (rr->type != T_PTR) continue;
1410 s = store_get(ssize);
1412 /* If an overlong response was received, the data will have been
1413 truncated and dn_expand may fail. */
1415 if (dn_expand(dnsa.answer, dnsa.answer + dnsa.answerlen,
1416 (uschar *)(rr->data), (DN_EXPAND_ARG4_TYPE)(s), ssize) < 0)
1418 log_write(0, LOG_MAIN, "host name alias list truncated for %s",
1419 sender_host_address);
1423 store_reset(s + Ustrlen(s) + 1);
1426 HDEBUG(D_host_lookup) debug_printf("IP address lookup yielded an "
1427 "empty name: treated as non-existent host name\n");
1430 if (sender_host_name == NULL) sender_host_name = s;
1432 while (*s != 0) { *s = tolower(*s); s++; }
1435 *aptr = NULL; /* End of alias list */
1436 store_pool = old_pool; /* Reset store pool */
1438 /* If we've found a names, break out of the "order" loop */
1440 if (sender_host_name != NULL) break;
1443 /* If the DNS lookup deferred, we must also defer. */
1445 if (rc == DNS_AGAIN)
1447 HDEBUG(D_host_lookup)
1448 debug_printf("IP address PTR lookup gave temporary error\n");
1453 /* Do a lookup using gethostbyaddr() - or equivalent */
1455 else if (strcmpic(ordername, US"byaddr") == 0)
1457 HDEBUG(D_host_lookup)
1458 debug_printf("IP address lookup using gethostbyaddr()\n");
1460 rc = host_name_lookup_byaddr();
1461 if (rc == DEFER) return rc; /* Can't carry on */
1462 if (rc == OK) break; /* Found a name */
1464 } /* Loop for bydns/byaddr scanning */
1466 /* If we have failed to find a name, return FAIL and log when required.
1467 NB host_lookup_msg must be in permanent store. */
1469 if (sender_host_name == NULL)
1471 if (host_checking || !log_testing_mode)
1472 log_write(L_host_lookup_failed, LOG_MAIN, "no host name found for IP "
1473 "address %s", sender_host_address);
1474 host_lookup_msg = US" (failed to find host name from IP address)";
1476 host_lookup_failed = TRUE;
1480 /* We have a host name. If we are running in the test harness, we want the host
1481 name and its alias to appear always the same way round. There are only ever two
1482 names in these tests. If one of them contains "alias", make sure it is second;
1483 otherwise put them in alphabetical order. */
1485 if (running_in_test_harness && *sender_host_aliases != NULL &&
1487 Ustrstr(sender_host_name, "alias") != NULL ||
1489 Ustrstr(*sender_host_aliases, "alias") == NULL &&
1490 Ustrcmp(sender_host_name, *sender_host_aliases) > 0
1494 uschar *temp = sender_host_name;
1495 sender_host_name = *sender_host_aliases;
1496 *sender_host_aliases = temp;
1499 /* Debug output what was found, after test harness swapping, for consistency */
1501 HDEBUG(D_host_lookup)
1503 uschar **aliases = sender_host_aliases;
1504 debug_printf("IP address lookup yielded %s\n", sender_host_name);
1505 while (*aliases != NULL) debug_printf(" alias %s\n", *aliases++);
1508 /* We need to verify that a forward lookup on the name we found does indeed
1509 correspond to the address. This is for security: in principle a malefactor who
1510 happened to own a reverse zone could set it to point to any names at all.
1512 This code was present in versions of Exim before 3.20. At that point I took it
1513 out because I thought that gethostbyaddr() did the check anyway. It turns out
1514 that this isn't always the case, so it's coming back in at 4.01. This version
1515 is actually better, because it also checks aliases.
1517 The code was made more robust at release 4.21. Prior to that, it accepted all
1518 the names if any of them had the correct IP address. Now the code checks all
1519 the names, and accepts only those that have the correct IP address. */
1521 save_hostname = sender_host_name; /* Save for error messages */
1522 aliases = sender_host_aliases;
1523 for (hname = sender_host_name; hname != NULL; hname = *aliases++)
1533 /* When called with the 5th argument FALSE, host_find_byname() won't return
1534 HOST_FOUND_LOCAL. If the incoming address is an IPv4 address expressed in
1535 IPv6 format, we must compare the IPv4 part to any IPv4 addresses. */
1537 if ((rc = host_find_byname(&h, NULL, NULL, FALSE)) == HOST_FOUND)
1540 uschar *address_ipv4 = (Ustrncmp(sender_host_address, "::ffff:", 7) == 0)?
1541 sender_host_address + 7 : sender_host_address;
1542 HDEBUG(D_host_lookup) debug_printf("checking addresses for %s\n", hname);
1543 for (hh = &h; hh != NULL; hh = hh->next)
1545 if ((Ustrcmp(hh->address, (Ustrchr(hh->address, ':') == NULL)?
1546 address_ipv4 : sender_host_address)) == 0)
1548 HDEBUG(D_host_lookup) debug_printf(" %s OK\n", hh->address);
1554 HDEBUG(D_host_lookup) debug_printf(" %s\n", hh->address);
1557 if (!ok) HDEBUG(D_host_lookup)
1558 debug_printf("no IP address for %s matched %s\n", hname,
1559 sender_host_address);
1561 else if (rc == HOST_FIND_AGAIN)
1563 HDEBUG(D_host_lookup) debug_printf("temporary error for host name lookup\n");
1568 HDEBUG(D_host_lookup) debug_printf("no IP addresses found for %s\n", hname);
1571 /* If this name is no good, and it's the sender name, set it null pro tem;
1572 if it's an alias, just remove it from the list. */
1576 if (hname == sender_host_name) sender_host_name = NULL; else
1578 uschar **a; /* Don't amalgamate - some */
1579 a = --aliases; /* compilers grumble */
1580 while (*a != NULL) { *a = a[1]; a++; }
1585 /* If sender_host_name == NULL, it means we didn't like the name. Replace
1586 it with the first alias, if there is one. */
1588 if (sender_host_name == NULL && *sender_host_aliases != NULL)
1589 sender_host_name = *sender_host_aliases++;
1591 /* If we now have a main name, all is well. */
1593 if (sender_host_name != NULL) return OK;
1595 /* We have failed to find an address that matches. */
1597 HDEBUG(D_host_lookup)
1598 debug_printf("%s does not match any IP address for %s\n",
1599 sender_host_address, save_hostname);
1601 /* This message must be in permanent store */
1603 old_pool = store_pool;
1604 store_pool = POOL_PERM;
1605 host_lookup_msg = string_sprintf(" (%s does not match any IP address for %s)",
1606 sender_host_address, save_hostname);
1607 store_pool = old_pool;
1609 host_lookup_failed = TRUE;
1616 /*************************************************
1617 * Find IP address(es) for host by name *
1618 *************************************************/
1620 /* The input is a host_item structure with the name filled in and the address
1621 field set to NULL. We use gethostbyname(). Of course, gethostbyname() may use
1622 the DNS, but it doesn't do MX processing. If more than one address is given,
1623 chain on additional host items, with other relevant fields copied.
1625 The second argument provides a host list (usually an IP list) of hosts to
1626 ignore. This makes it possible to ignore IPv6 link-local addresses or loopback
1627 addresses in unreasonable places.
1629 The lookup may result in a change of name. For compatibility with the dns
1630 lookup, return this via fully_qualified_name as well as updating the host item.
1631 The lookup may also yield more than one IP address, in which case chain on
1632 subsequent host_item structures.
1635 host a host item with the name and MX filled in;
1636 the address is to be filled in;
1637 multiple IP addresses cause other host items to be
1639 ignore_target_hosts a list of hosts to ignore
1640 fully_qualified_name if not NULL, set to point to host name for
1641 compatibility with host_find_bydns
1642 local_host_check TRUE if a check for the local host is wanted
1644 Returns: HOST_FIND_FAILED Failed to find the host or domain
1645 HOST_FIND_AGAIN Try again later
1646 HOST_FOUND Host found - data filled in
1647 HOST_FOUND_LOCAL Host found and is the local host
1651 host_find_byname(host_item *host, uschar *ignore_target_hosts,
1652 uschar **fully_qualified_name, BOOL local_host_check)
1654 int i, yield, times;
1656 host_item *last = NULL;
1657 BOOL temp_error = FALSE;
1659 /* In an IPv6 world, we need to scan for both kinds of address, so go round the
1660 loop twice. Note that we have ensured that AF_INET6 is defined even in an IPv4
1661 world, which makes for slightly tidier code. However, if dns_ipv4_lookup
1662 matches the domain, we also just do IPv4 lookups here (except when testing
1669 if (dns_ipv4_lookup != NULL &&
1670 match_isinlist(host->name, &dns_ipv4_lookup, 0, NULL, NULL, MCL_DOMAIN,
1672 { af = AF_INET; times = 1; }
1674 #endif /* STAND_ALONE */
1676 { af = AF_INET6; times = 2; }
1678 /* No IPv6 support */
1680 #else /* HAVE_IPV6 */
1682 #endif /* HAVE_IPV6 */
1684 /* Initialize the flag that gets set for DNS syntax check errors, so that the
1685 interface to this function can be similar to host_find_bydns. */
1687 host_find_failed_syntax = FALSE;
1689 /* Loop to look up both kinds of address in an IPv6 world */
1691 for (i = 1; i <= times;
1693 af = AF_INET, /* If 2 passes, IPv4 on the second */
1699 struct hostent *hostdata;
1702 #if HAVE_GETIPNODEBYNAME
1703 hostdata = getipnodebyname(CS host->name, af, 0, &error_num);
1705 hostdata = gethostbyname2(CS host->name, af);
1706 error_num = h_errno;
1709 hostdata = gethostbyname(CS host->name);
1710 error_num = h_errno;
1713 if (hostdata == NULL)
1718 case HOST_NOT_FOUND: error = US"HOST_NOT_FOUND"; break;
1719 case TRY_AGAIN: error = US"TRY_AGAIN"; break;
1720 case NO_RECOVERY: error = US"NO_RECOVERY"; break;
1721 case NO_DATA: error = US"NO_DATA"; break;
1722 #if NO_DATA != NO_ADDRESS
1723 case NO_ADDRESS: error = US"NO_ADDRESS"; break;
1725 default: error = US"?"; break;
1728 DEBUG(D_host_lookup) debug_printf("%s returned %d (%s)\n",
1730 #if HAVE_GETIPNODEBYNAME
1731 (af == AF_INET6)? "getipnodebyname(af=inet6)" : "getipnodebyname(af=inet)",
1733 (af == AF_INET6)? "gethostbyname2(af=inet6)" : "gethostbyname2(af=inet)",
1740 if (error_num == TRY_AGAIN || error_num == NO_RECOVERY) temp_error = TRUE;
1743 if ((hostdata->h_addr_list)[0] == NULL) continue;
1745 /* Replace the name with the fully qualified one if necessary, and fill in
1746 the fully_qualified_name pointer. */
1748 if (hostdata->h_name[0] != 0 &&
1749 Ustrcmp(host->name, hostdata->h_name) != 0)
1750 host->name = string_copy_dnsdomain((uschar *)hostdata->h_name);
1751 if (fully_qualified_name != NULL) *fully_qualified_name = host->name;
1753 /* Get the list of addresses. IPv4 and IPv6 addresses can be distinguished
1754 by their different lengths. Scan the list, ignoring any that are to be
1755 ignored, and build a chain from the rest. */
1757 ipv4_addr = hostdata->h_length == sizeof(struct in_addr);
1759 for (addrlist = USS hostdata->h_addr_list; *addrlist != NULL; addrlist++)
1761 uschar *text_address =
1762 host_ntoa(ipv4_addr? AF_INET:AF_INET6, *addrlist, NULL, NULL);
1765 if (ignore_target_hosts != NULL &&
1766 verify_check_this_host(&ignore_target_hosts, NULL, host->name,
1767 text_address, NULL) == OK)
1769 DEBUG(D_host_lookup)
1770 debug_printf("ignored host %s [%s]\n", host->name, text_address);
1775 /* If this is the first address, last == NULL and we put the data in the
1780 host->address = text_address;
1781 host->port = PORT_NONE;
1782 host->status = hstatus_unknown;
1783 host->why = hwhy_unknown;
1787 /* Else add further host item blocks for any other addresses, keeping
1792 host_item *next = store_get(sizeof(host_item));
1793 next->name = host->name;
1794 next->mx = host->mx;
1795 next->address = text_address;
1796 next->port = PORT_NONE;
1797 next->status = hstatus_unknown;
1798 next->why = hwhy_unknown;
1800 next->next = last->next;
1807 /* If no hosts were found, the address field in the original host block will be
1808 NULL. If temp_error is set, at least one of the lookups gave a temporary error,
1809 so we pass that back. */
1811 if (host->address == NULL)
1815 (message_id[0] == 0 && smtp_in != NULL)?
1816 string_sprintf("no IP address found for host %s (during %s)", host->name,
1817 smtp_get_connection_info()) :
1819 string_sprintf("no IP address found for host %s", host->name);
1821 HDEBUG(D_host_lookup) debug_printf("%s\n", msg);
1822 if (temp_error) return HOST_FIND_AGAIN;
1823 if (host_checking || !log_testing_mode)
1824 log_write(L_host_lookup_failed, LOG_MAIN, "%s", msg);
1825 return HOST_FIND_FAILED;
1828 /* Remove any duplicate IP addresses, then check to see if this is the local
1829 host if required. */
1831 host_remove_duplicates(host, &last);
1832 yield = local_host_check?
1833 host_scan_for_local_hosts(host, &last, NULL) : HOST_FOUND;
1835 /* When running in the test harness, sort into the order of addresses so as to
1836 get repeatability. */
1838 if (running_in_test_harness) sort_addresses(host, last);
1840 HDEBUG(D_host_lookup)
1843 if (fully_qualified_name != NULL)
1844 debug_printf("fully qualified name = %s\n", *fully_qualified_name);
1845 debug_printf("%s looked up these IP addresses:\n",
1847 #if HAVE_GETIPNODEBYNAME
1856 for (h = host; h != last->next; h = h->next)
1857 debug_printf(" name=%s address=%s\n", h->name,
1858 (h->address == NULL)? US"<null>" : h->address);
1861 /* Return the found status. */
1868 /*************************************************
1869 * Fill in a host address from the DNS *
1870 *************************************************/
1872 /* Given a host item, with its name and mx fields set, and its address field
1873 set to NULL, fill in its IP address from the DNS. If it is multi-homed, create
1874 additional host items for the additional addresses, copying all the other
1875 fields, and randomizing the order.
1877 On IPv6 systems, A6 records are sought first (but only if support for A6 is
1878 configured - they may never become mainstream), then AAAA records are sought,
1879 and finally A records are sought as well.
1881 The host name may be changed if the DNS returns a different name - e.g. fully
1882 qualified or changed via CNAME. If fully_qualified_name is not NULL, dns_lookup
1883 ensures that it points to the fully qualified name. However, this is the fully
1884 qualified version of the original name; if a CNAME is involved, the actual
1885 canonical host name may be different again, and so we get it directly from the
1886 relevant RR. Note that we do NOT change the mx field of the host item in this
1887 function as it may be called to set the addresses of hosts taken from MX
1891 host points to the host item we're filling in
1892 lastptr points to pointer to last host item in a chain of
1893 host items (may be updated if host is last and gets
1894 extended because multihomed)
1895 ignore_target_hosts list of hosts to ignore
1896 allow_ip if TRUE, recognize an IP address and return it
1897 fully_qualified_name if not NULL, return fully qualified name here if
1898 the contents are different (i.e. it must be preset
1901 Returns: HOST_FIND_FAILED couldn't find A record
1902 HOST_FIND_AGAIN try again later
1903 HOST_FOUND found AAAA and/or A record(s)
1904 HOST_IGNORED found, but all IPs ignored
1908 set_address_from_dns(host_item *host, host_item **lastptr,
1909 uschar *ignore_target_hosts, BOOL allow_ip, uschar **fully_qualified_name)
1912 host_item *thishostlast = NULL; /* Indicates not yet filled in anything */
1913 BOOL v6_find_again = FALSE;
1916 /* If allow_ip is set, a name which is an IP address returns that value
1917 as its address. This is used for MX records when allow_mx_to_ip is set, for
1918 those sites that feel they have to flaunt the RFC rules. */
1920 if (allow_ip && string_is_ip_address(host->name, NULL) != 0)
1923 if (ignore_target_hosts != NULL &&
1924 verify_check_this_host(&ignore_target_hosts, NULL, host->name,
1925 host->name, NULL) == OK)
1926 return HOST_IGNORED;
1929 host->address = host->name;
1930 host->port = PORT_NONE;
1934 /* On an IPv6 system, go round the loop up to three times, looking for A6 and
1935 AAAA records the first two times. However, unless doing standalone testing, we
1936 force an IPv4 lookup if the domain matches dns_ipv4_lookup is set. Since A6
1937 records look like being abandoned, support them only if explicitly configured
1938 to do so. On an IPv4 system, go round the loop once only, looking only for A
1944 if (dns_ipv4_lookup != NULL &&
1945 match_isinlist(host->name, &dns_ipv4_lookup, 0, NULL, NULL, MCL_DOMAIN,
1947 i = 0; /* look up A records only */
1949 #endif /* STAND_ALONE */
1952 i = 2; /* look up A6 and AAAA and A records */
1954 i = 1; /* look up AAAA and A records */
1955 #endif /* SUPPORT_A6 */
1957 /* The IPv4 world */
1959 #else /* HAVE_IPV6 */
1960 i = 0; /* look up A records only */
1961 #endif /* HAVE_IPV6 */
1965 static int types[] = { T_A, T_AAAA, T_A6 };
1966 int type = types[i];
1967 int randoffset = (i == 0)? 500 : 0; /* Ensures v6 sorts before v4 */
1971 int rc = dns_lookup(&dnsa, host->name, type, fully_qualified_name);
1973 /* We want to return HOST_FIND_AGAIN if one of the A, A6, or AAAA lookups
1974 fails or times out, but not if another one succeeds. (In the early
1975 IPv6 days there are name servers that always fail on AAAA, but are happy
1976 to give out an A record. We want to proceed with that A record.) */
1978 if (rc != DNS_SUCCEED)
1980 if (i == 0) /* Just tried for an A record, i.e. end of loop */
1982 if (host->address != NULL) return HOST_FOUND; /* A6 or AAAA was found */
1983 if (rc == DNS_AGAIN || rc == DNS_FAIL || v6_find_again)
1984 return HOST_FIND_AGAIN;
1985 return HOST_FIND_FAILED; /* DNS_NOMATCH or DNS_NODATA */
1988 /* Tried for an A6 or AAAA record: remember if this was a temporary
1989 error, and look for the next record type. */
1991 if (rc != DNS_NOMATCH && rc != DNS_NODATA) v6_find_again = TRUE;
1995 /* Lookup succeeded: fill in the given host item with the first non-ignored
1996 address found; create additional items for any others. A single A6 record
1997 may generate more than one address. */
1999 for (rr = dns_next_rr(&dnsa, &dnss, RESET_ANSWERS);
2001 rr = dns_next_rr(&dnsa, &dnss, RESET_NEXT))
2003 if (rr->type == type)
2005 /* dns_address *da = dns_address_from_rr(&dnsa, rr); */
2008 da = dns_address_from_rr(&dnsa, rr);
2010 DEBUG(D_host_lookup)
2013 debug_printf("no addresses extracted from A6 RR for %s\n",
2017 /* This loop runs only once for A and AAAA records, but may run
2018 several times for an A6 record that generated multiple addresses. */
2020 for (; da != NULL; da = da->next)
2023 if (ignore_target_hosts != NULL &&
2024 verify_check_this_host(&ignore_target_hosts, NULL,
2025 host->name, da->address, NULL) == OK)
2027 DEBUG(D_host_lookup)
2028 debug_printf("ignored host %s [%s]\n", host->name, da->address);
2033 /* If this is the first address, stick it in the given host block,
2034 and change the name if the returned RR has a different name. */
2036 if (thishostlast == NULL)
2038 if (strcmpic(host->name, rr->name) != 0)
2039 host->name = string_copy_dnsdomain(rr->name);
2040 host->address = da->address;
2041 host->port = PORT_NONE;
2042 host->sort_key = host->mx * 1000 + random_number(500) + randoffset;
2043 host->status = hstatus_unknown;
2044 host->why = hwhy_unknown;
2045 thishostlast = host;
2048 /* Not the first address. Check for, and ignore, duplicates. Then
2049 insert in the chain at a random point. */
2056 /* End of our local chain is specified by "thishostlast". */
2058 for (next = host;; next = next->next)
2060 if (Ustrcmp(CS da->address, next->address) == 0) break;
2061 if (next == thishostlast) { next = NULL; break; }
2063 if (next != NULL) continue; /* With loop for next address */
2065 /* Not a duplicate */
2067 new_sort_key = host->mx * 1000 + random_number(500) + randoffset;
2068 next = store_get(sizeof(host_item));
2070 /* New address goes first: insert the new block after the first one
2071 (so as not to disturb the original pointer) but put the new address
2072 in the original block. */
2074 if (new_sort_key < host->sort_key)
2078 host->address = da->address;
2079 host->port = PORT_NONE;
2080 host->sort_key = new_sort_key;
2081 if (thishostlast == host) thishostlast = next; /* Local last */
2082 if (*lastptr == host) *lastptr = next; /* Global last */
2085 /* Otherwise scan down the addresses for this host to find the
2086 one to insert after. */
2090 host_item *h = host;
2091 while (h != thishostlast)
2093 if (new_sort_key < h->next->sort_key) break;
2098 next->address = da->address;
2099 next->port = PORT_NONE;
2100 next->sort_key = new_sort_key;
2101 if (h == thishostlast) thishostlast = next; /* Local last */
2102 if (h == *lastptr) *lastptr = next; /* Global last */
2110 /* Control gets here only if the third lookup (the A record) succeeded.
2111 However, the address may not be filled in if it was ignored. */
2113 return (host->address == NULL)? HOST_IGNORED : HOST_FOUND;
2119 /*************************************************
2120 * Find IP addresses and names for host via DNS *
2121 *************************************************/
2123 /* The input is a host_item structure with the name filled in and the address
2124 field set to NULL. This may be in a chain of other host items. The lookup may
2125 result in more than one IP address, in which case we must created new host
2126 blocks for the additional addresses, and insert them into the chain. The
2127 original name may not be fully qualified. Use the fully_qualified_name argument
2128 to return the official name, as returned by the resolver.
2131 host point to initial host item
2132 ignore_target_hosts a list of hosts to ignore
2133 whichrrs flags indicating which RRs to look for:
2134 HOST_FIND_BY_SRV => look for SRV
2135 HOST_FIND_BY_MX => look for MX
2136 HOST_FIND_BY_A => look for A or AAAA
2137 also flags indicating how the lookup is done
2138 HOST_FIND_QUALIFY_SINGLE ) passed to the
2139 HOST_FIND_SEARCH_PARENTS ) resolver
2140 srv_service when SRV used, the service name
2141 srv_fail_domains DNS errors for these domains => assume nonexist
2142 mx_fail_domains DNS errors for these domains => assume nonexist
2143 fully_qualified_name if not NULL, return fully-qualified name
2144 removed set TRUE if local host was removed from the list
2146 Returns: HOST_FIND_FAILED Failed to find the host or domain;
2147 if there was a syntax error,
2148 host_find_failed_syntax is set.
2149 HOST_FIND_AGAIN Could not resolve at this time
2150 HOST_FOUND Host found
2151 HOST_FOUND_LOCAL The lowest MX record points to this
2152 machine, if MX records were found, or
2153 an A record that was found contains
2154 an address of the local host
2158 host_find_bydns(host_item *host, uschar *ignore_target_hosts, int whichrrs,
2159 uschar *srv_service, uschar *srv_fail_domains, uschar *mx_fail_domains,
2160 uschar **fully_qualified_name, BOOL *removed)
2162 host_item *h, *last;
2170 /* Set the default fully qualified name to the incoming name, initialize the
2171 resolver if necessary, set up the relevant options, and initialize the flag
2172 that gets set for DNS syntax check errors. */
2174 if (fully_qualified_name != NULL) *fully_qualified_name = host->name;
2175 dns_init((whichrrs & HOST_FIND_QUALIFY_SINGLE) != 0,
2176 (whichrrs & HOST_FIND_SEARCH_PARENTS) != 0);
2177 host_find_failed_syntax = FALSE;
2179 /* First, if requested, look for SRV records. The service name is given; we
2180 assume TCP progocol. DNS domain names are constrained to a maximum of 256
2181 characters, so the code below should be safe. */
2183 if ((whichrrs & HOST_FIND_BY_SRV) != 0)
2186 uschar *temp_fully_qualified_name = buffer;
2189 (void)sprintf(CS buffer, "_%s._tcp.%n%.256s", srv_service, &prefix_length,
2193 /* Search for SRV records. If the fully qualified name is different to
2194 the input name, pass back the new original domain, without the prepended
2197 rc = dns_lookup(&dnsa, buffer, ind_type, &temp_fully_qualified_name);
2198 if (temp_fully_qualified_name != buffer && fully_qualified_name != NULL)
2199 *fully_qualified_name = temp_fully_qualified_name + prefix_length;
2201 /* On DNS failures, we give the "try again" error unless the domain is
2202 listed as one for which we continue. */
2204 if (rc == DNS_FAIL || rc == DNS_AGAIN)
2206 if (match_isinlist(host->name, &srv_fail_domains, 0, NULL, NULL, MCL_DOMAIN,
2208 return HOST_FIND_AGAIN;
2209 DEBUG(D_host_lookup) debug_printf("DNS_%s treated as DNS_NODATA "
2210 "(domain in srv_fail_domains)\n", (rc == DNS_FAIL)? "FAIL":"AGAIN");
2214 /* If we did not find any SRV records, search the DNS for MX records, if
2215 requested to do so. If the result is DNS_NOMATCH, it means there is no such
2216 domain, and there's no point in going on to look for address records with the
2217 same domain. The result will be DNS_NODATA if the domain exists but has no MX
2218 records. On DNS failures, we give the "try again" error unless the domain is
2219 listed as one for which we continue. */
2221 if (rc != DNS_SUCCEED && (whichrrs & HOST_FIND_BY_MX) != 0)
2224 rc = dns_lookup(&dnsa, host->name, ind_type, fully_qualified_name);
2225 if (rc == DNS_NOMATCH) return HOST_FIND_FAILED;
2226 if (rc == DNS_FAIL || rc == DNS_AGAIN)
2228 if (match_isinlist(host->name, &mx_fail_domains, 0, NULL, NULL, MCL_DOMAIN,
2230 return HOST_FIND_AGAIN;
2231 DEBUG(D_host_lookup) debug_printf("DNS_%s treated as DNS_NODATA "
2232 "(domain in mx_fail_domains)\n", (rc == DNS_FAIL)? "FAIL":"AGAIN");
2236 /* If we haven't found anything yet, and we are requested to do so, try for an
2237 A or AAAA record. If we find it (or them) check to see that it isn't the local
2240 if (rc != DNS_SUCCEED)
2242 if ((whichrrs & HOST_FIND_BY_A) == 0)
2244 DEBUG(D_host_lookup) debug_printf("Address records are not being sought\n");
2245 return HOST_FIND_FAILED;
2248 last = host; /* End of local chainlet */
2250 host->port = PORT_NONE;
2251 rc = set_address_from_dns(host, &last, ignore_target_hosts, FALSE,
2252 fully_qualified_name);
2254 /* If one or more address records have been found, check that none of them
2255 are local. Since we know the host items all have their IP addresses
2256 inserted, host_scan_for_local_hosts() can only return HOST_FOUND or
2257 HOST_FOUND_LOCAL. We do not need to scan for duplicate IP addresses here,
2258 because set_address_from_dns() removes them. */
2260 if (rc == HOST_FOUND)
2261 rc = host_scan_for_local_hosts(host, &last, removed);
2263 if (rc == HOST_IGNORED) rc = HOST_FIND_FAILED; /* No special action */
2265 /* When running in the test harness, sort into the order of addresses so as
2266 to get repeatability. */
2268 if (running_in_test_harness) sort_addresses(host, last);
2270 DEBUG(D_host_lookup)
2273 if (host->address != NULL)
2275 if (fully_qualified_name != NULL)
2276 debug_printf("fully qualified name = %s\n", *fully_qualified_name);
2277 for (h = host; h != last->next; h = h->next)
2278 debug_printf("%s %s mx=%d sort=%d %s\n", h->name,
2279 (h->address == NULL)? US"<null>" : h->address, h->mx, h->sort_key,
2280 (h->status >= hstatus_unusable)? US"*" : US"");
2287 /* We have found one or more MX or SRV records. Sort them according to
2288 precedence. Put the data for the first one into the existing host block, and
2289 insert new host_item blocks into the chain for the remainder. For equal
2290 precedences one is supposed to randomize the order. To make this happen, the
2291 sorting is actually done on the MX value * 1000 + a random number. This is put
2292 into a host field called sort_key.
2294 In the case of hosts with both IPv6 and IPv4 addresses, we want to choose the
2295 IPv6 address in preference. At this stage, we don't know what kind of address
2296 the host has. We choose a random number < 500; if later we find an A record
2297 first, we add 500 to the random number. Then for any other address records, we
2298 use random numbers in the range 0-499 for AAAA records and 500-999 for A
2301 At this point we remove any duplicates that point to the same host, retaining
2302 only the one with the lowest precedence. We cannot yet check for precedence
2303 greater than that of the local host, because that test cannot be properly done
2304 until the addresses have been found - an MX record may point to a name for this
2305 host which is not the primary hostname. */
2307 last = NULL; /* Indicates that not even the first item is filled yet */
2309 for (rr = dns_next_rr(&dnsa, &dnss, RESET_ANSWERS);
2311 rr = dns_next_rr(&dnsa, &dnss, RESET_NEXT))
2314 int weight = 0; /* For SRV records */
2315 int port = PORT_NONE; /* For SRV records */
2316 uschar *s; /* MUST be unsigned for GETSHORT */
2319 if (rr->type != ind_type) continue;
2321 GETSHORT(precedence, s); /* Pointer s is advanced */
2323 /* For MX records, we use a random "weight" which causes multiple records of
2324 the same precedence to sort randomly. */
2326 if (ind_type == T_MX)
2328 weight = random_number(500);
2331 /* SRV records are specified with a port and a weight. The weight is used
2332 in a special algorithm. However, to start with, we just use it to order the
2333 records of equal priority (precedence). */
2337 GETSHORT(weight, s);
2341 /* Get the name of the host pointed to. */
2343 (void)dn_expand(dnsa.answer, dnsa.answer + dnsa.answerlen, s,
2344 (DN_EXPAND_ARG4_TYPE)data, sizeof(data));
2346 /* Check that we haven't already got this host on the chain; if we have,
2347 keep only the lower precedence. This situation shouldn't occur, but you
2348 never know what junk might get into the DNS (and this case has been seen on
2349 more than one occasion). */
2351 if (last != NULL) /* This is not the first record */
2353 host_item *prev = NULL;
2355 for (h = host; h != last->next; prev = h, h = h->next)
2357 if (strcmpic(h->name, data) == 0)
2359 DEBUG(D_host_lookup)
2360 debug_printf("discarded duplicate host %s (MX=%d)\n", data,
2361 (precedence > h->mx)? precedence : h->mx);
2362 if (precedence >= h->mx) goto NEXT_MX_RR; /* Skip greater precedence */
2363 if (h == host) /* Override first item */
2366 host->sort_key = precedence * 1000 + weight;
2370 /* Unwanted host item is not the first in the chain, so we can get
2371 get rid of it by cutting it out. */
2373 prev->next = h->next;
2374 if (h == last) last = prev;
2380 /* If this is the first MX or SRV record, put the data into the existing host
2381 block. Otherwise, add a new block in the correct place; if it has to be
2382 before the first block, copy the first block's data to a new second block. */
2386 host->name = string_copy_dnsdomain(data);
2387 host->address = NULL;
2389 host->mx = precedence;
2390 host->sort_key = precedence * 1000 + weight;
2391 host->status = hstatus_unknown;
2392 host->why = hwhy_unknown;
2396 /* Make a new host item and seek the correct insertion place */
2400 int sort_key = precedence * 1000 + weight;
2401 host_item *next = store_get(sizeof(host_item));
2402 next->name = string_copy_dnsdomain(data);
2403 next->address = NULL;
2405 next->mx = precedence;
2406 next->sort_key = sort_key;
2407 next->status = hstatus_unknown;
2408 next->why = hwhy_unknown;
2411 /* Handle the case when we have to insert before the first item. */
2413 if (sort_key < host->sort_key)
2420 if (last == host) last = next;
2423 /* Else scan down the items we have inserted as part of this exercise;
2424 don't go further. */
2428 for (h = host; h != last; h = h->next)
2430 if (sort_key < h->next->sort_key)
2432 next->next = h->next;
2438 /* Join on after the last host item that's part of this
2439 processing if we haven't stopped sooner. */
2443 next->next = last->next;
2450 NEXT_MX_RR: continue;
2453 /* If the list of hosts was obtained from SRV records, there are two things to
2454 do. First, if there is only one host, and it's name is ".", it means there is
2455 no SMTP service at this domain. Otherwise, we have to sort the hosts of equal
2456 priority according to their weights, using an algorithm that is defined in RFC
2457 2782. The hosts are currently sorted by priority and weight. For each priority
2458 group we have to pick off one host and put it first, and then repeat for any
2459 remaining in the same priority group. */
2461 if (ind_type == T_SRV)
2465 if (host == last && host->name[0] == 0)
2467 DEBUG(D_host_lookup) debug_printf("the single SRV record is \".\"\n");
2468 return HOST_FIND_FAILED;
2471 DEBUG(D_host_lookup)
2473 debug_printf("original ordering of hosts from SRV records:\n");
2474 for (h = host; h != last->next; h = h->next)
2475 debug_printf(" %s P=%d W=%d\n", h->name, h->mx, h->sort_key % 1000);
2478 for (pptr = &host, h = host; h != last; pptr = &(h->next), h = h->next)
2483 /* Find the last following host that has the same precedence. At the same
2484 time, compute the sum of the weights and the running totals. These can be
2485 stored in the sort_key field. */
2487 for (hh = h; hh != last; hh = hh->next)
2489 int weight = hh->sort_key % 1000; /* was precedence * 1000 + weight */
2492 if (hh->mx != hh->next->mx) break;
2495 /* If there's more than one host at this precedence (priority), we need to
2496 pick one to go first. */
2502 int randomizer = random_number(sum + 1);
2504 for (ppptr = pptr, hhh = h;
2506 ppptr = &(hhh->next), hhh = hhh->next)
2508 if (hhh->sort_key >= randomizer) break;
2511 /* hhh now points to the host that should go first; ppptr points to the
2512 place that points to it. Unfortunately, if the start of the minilist is
2513 the start of the entire list, we can't just swap the items over, because
2514 we must not change the value of host, since it is passed in from outside.
2515 One day, this could perhaps be changed.
2517 The special case is fudged by putting the new item *second* in the chain,
2518 and then transferring the data between the first and second items. We
2519 can't just swap the first and the chosen item, because that would mean
2520 that an item with zero weight might no longer be first. */
2524 *ppptr = hhh->next; /* Cuts it out of the chain */
2528 host_item temp = *h;
2531 hhh->next = temp.next;
2537 hhh->next = h; /* The rest of the chain follows it */
2538 *pptr = hhh; /* It takes the place of h */
2539 h = hhh; /* It's now the start of this minilist */
2544 /* A host has been chosen to be first at this priority and h now points
2545 to this host. There may be others at the same priority, or others at a
2546 different priority. Before we leave this host, we need to put back a sort
2547 key of the traditional MX kind, in case this host is multihomed, because
2548 the sort key is used for ordering the multiple IP addresses. We do not need
2549 to ensure that these new sort keys actually reflect the order of the hosts,
2552 h->sort_key = h->mx * 1000 + random_number(500);
2553 } /* Move on to the next host */
2556 /* Now we have to ensure addresses exist for all the hosts. We have ensured
2557 above that the names in the host items are all unique. The addresses may have
2558 been returned in the additional data section of the DNS query. Because it is
2559 more expensive to scan the returned DNS records (because you have to expand the
2560 names) we do a single scan over them, and multiple scans of the chain of host
2561 items (which is typically only 3 or 4 long anyway.) Add extra host items for
2562 multi-homed hosts. */
2564 for (rr = dns_next_rr(&dnsa, &dnss, RESET_ADDITIONAL);
2566 rr = dns_next_rr(&dnsa, &dnss, RESET_NEXT))
2569 int status = hstatus_unknown;
2570 int why = hwhy_unknown;
2575 && rr->type != T_AAAA
2582 /* Find the first host that matches this record's name. If there isn't
2583 one, move on to the next RR. */
2585 for (h = host; h != last->next; h = h->next)
2586 { if (strcmpic(h->name, rr->name) == 0) break; }
2587 if (h == last->next) continue;
2589 /* For IPv4 addresses, add 500 to the random part of the sort key, to ensure
2590 they sort after IPv6 addresses. */
2592 randoffset = (rr->type == T_A)? 500 : 0;
2594 /* Get the list of textual addresses for this RR. There may be more than one
2595 if it is an A6 RR. Then loop to handle multiple addresses from an A6 record.
2596 If there are none, nothing will get done - the record is ignored. */
2598 for (da = dns_address_from_rr(&dnsa, rr); da != NULL; da = da->next)
2600 /* Set status for an ignorable host. */
2603 if (ignore_target_hosts != NULL &&
2604 verify_check_this_host(&ignore_target_hosts, NULL, h->name,
2605 da->address, NULL) == OK)
2607 DEBUG(D_host_lookup)
2608 debug_printf("ignored host %s [%s]\n", h->name, da->address);
2609 status = hstatus_unusable;
2614 /* If the address is already set for this host, it may be that
2615 we just have a duplicate DNS record. Alternatively, this may be
2616 a multi-homed host. Search all items with the same host name
2617 (they will all be together) and if this address is found, skip
2620 if (h->address != NULL)
2623 host_item *thishostlast;
2628 if (hh->address != NULL && Ustrcmp(CS da->address, hh->address) == 0)
2629 goto DNS_NEXT_RR; /* Need goto to escape from inner loop */
2633 while (hh != last->next && strcmpic(hh->name, rr->name) == 0);
2635 /* We have a multi-homed host, since we have a new address for
2636 an existing name. Create a copy of the current item, and give it
2637 the new address. RRs can be in arbitrary order, but one is supposed
2638 to randomize the addresses of multi-homed hosts, so compute a new
2639 sorting key and do that. [Latest SMTP RFC says not to randomize multi-
2640 homed hosts, but to rely on the resolver. I'm not happy about that -
2641 caching in the resolver will not rotate as often as the name server
2644 new_sort_key = h->mx * 1000 + random_number(500) + randoffset;
2645 hh = store_get(sizeof(host_item));
2647 /* New address goes first: insert the new block after the first one
2648 (so as not to disturb the original pointer) but put the new address
2649 in the original block. */
2651 if (new_sort_key < h->sort_key)
2653 *hh = *h; /* Note: copies the port */
2655 h->address = da->address;
2656 h->sort_key = new_sort_key;
2661 /* Otherwise scan down the addresses for this host to find the
2662 one to insert after. */
2666 while (h != thishostlast)
2668 if (new_sort_key < h->next->sort_key) break;
2671 *hh = *h; /* Note: copies the port */
2673 hh->address = da->address;
2674 hh->sort_key = new_sort_key;
2675 hh->status = status;
2679 if (h == last) last = hh; /* Inserted after last */
2682 /* The existing item doesn't have its address set yet, so just set it.
2683 Ensure that an IPv4 address gets its sort key incremented in case an IPv6
2684 address is found later. */
2688 h->address = da->address; /* Port should be set already */
2691 h->sort_key += randoffset;
2693 } /* Loop for addresses extracted from one RR */
2695 /* Carry on to the next RR. It would be nice to be able to be able to stop
2696 when every host on the list has an address, but we can't be sure there won't
2697 be an additional address for a multi-homed host further down the list, so
2698 we have to continue to the end. */
2700 DNS_NEXT_RR: continue;
2703 /* Set the default yield to failure */
2705 yield = HOST_FIND_FAILED;
2707 /* If we haven't found all the addresses in the additional section, we
2708 need to search for A or AAAA records explicitly. The names shouldn't point to
2709 CNAMES, but we use the general lookup function that handles them, just
2710 in case. If any lookup gives a soft error, change the default yield.
2712 For these DNS lookups, we must disable qualify_single and search_parents;
2713 otherwise invalid host names obtained from MX or SRV records can cause trouble
2714 if they happen to match something local. */
2716 dns_init(FALSE, FALSE);
2718 for (h = host; h != last->next; h = h->next)
2720 if (h->address != NULL || h->status == hstatus_unusable) continue;
2721 rc = set_address_from_dns(h, &last, ignore_target_hosts, allow_mx_to_ip, NULL);
2722 if (rc != HOST_FOUND)
2724 h->status = hstatus_unusable;
2725 if (rc == HOST_FIND_AGAIN)
2728 h->why = hwhy_deferred;
2731 h->why = (rc == HOST_IGNORED)? hwhy_ignored : hwhy_failed;
2735 /* Scan the list for any hosts that are marked unusable because they have
2736 been explicitly ignored, and remove them from the list, as if they did not
2737 exist. If we end up with just a single, ignored host, flatten its fields as if
2738 nothing was found. */
2740 if (ignore_target_hosts != NULL)
2742 host_item *prev = NULL;
2743 for (h = host; h != last->next; h = h->next)
2746 if (h->why != hwhy_ignored) /* Non ignored host, just continue */
2748 else if (prev == NULL) /* First host is ignored */
2750 if (h != last) /* First is not last */
2752 if (h->next == last) last = h; /* Overwrite it with next */
2753 *h = *(h->next); /* and reprocess it. */
2754 goto REDO; /* C should have redo, like Perl */
2757 else /* Ignored host is not first - */
2759 prev->next = h->next;
2760 if (h == last) last = prev;
2764 if (host->why == hwhy_ignored) host->address = NULL;
2767 /* There is still one complication in the case of IPv6. Although the code above
2768 arranges that IPv6 addresses take precedence over IPv4 addresses for multihomed
2769 hosts, it doesn't do this for addresses that apply to different hosts with the
2770 same MX precedence, because the sorting on MX precedence happens first. So we
2771 have to make another pass to check for this case. We ensure that, within a
2772 single MX preference value, IPv6 addresses come first. This can separate the
2773 addresses of a multihomed host, but that should not matter. */
2778 for (h = host; h != last; h = h->next)
2781 host_item *next = h->next;
2782 if (h->mx != next->mx || /* If next is different MX value */
2783 (h->sort_key % 1000) < 500 || /* OR this one is IPv6 */
2784 (next->sort_key % 1000) >= 500) /* OR next is IPv4 */
2785 continue; /* move on to next */
2787 temp.next = next->next;
2795 /* When running in the test harness, we want the hosts always to be in the same
2796 order so that the debugging output is the same and can be compared. Having a
2797 fixed set of "random" numbers doesn't actually achieve this, because the RRs
2798 come back from the resolver in a random order, so the non-random random numbers
2799 get used in a different order. We therefore have to sort the hosts that have
2800 the same MX values. We chose do to this by their name and then by IP address.
2801 The fact that the sort is slow matters not - this is testing only! */
2803 if (running_in_test_harness)
2809 for (h = host; h != last; h = h->next)
2811 int c = Ustrcmp(h->name, h->next->name);
2812 if (c == 0) c = Ustrcmp(h->address, h->next->address);
2813 if (h->mx == h->next->mx && c > 0)
2815 host_item *next = h->next;
2816 host_item temp = *h;
2817 temp.next = next->next;
2828 /* Remove any duplicate IP addresses and then scan the list of hosts for any
2829 whose IP addresses are on the local host. If any are found, all hosts with the
2830 same or higher MX values are removed. However, if the local host has the lowest
2831 numbered MX, then HOST_FOUND_LOCAL is returned. Otherwise, if at least one host
2832 with an IP address is on the list, HOST_FOUND is returned. Otherwise,
2833 HOST_FIND_FAILED is returned, but in this case do not update the yield, as it
2834 might have been set to HOST_FIND_AGAIN just above here. If not, it will already
2835 be HOST_FIND_FAILED. */
2837 host_remove_duplicates(host, &last);
2838 rc = host_scan_for_local_hosts(host, &last, removed);
2839 if (rc != HOST_FIND_FAILED) yield = rc;
2841 DEBUG(D_host_lookup)
2843 if (fully_qualified_name != NULL)
2844 debug_printf("fully qualified name = %s\n", *fully_qualified_name);
2845 debug_printf("host_find_bydns yield = %s (%d); returned hosts:\n",
2846 (yield == HOST_FOUND)? "HOST_FOUND" :
2847 (yield == HOST_FOUND_LOCAL)? "HOST_FOUND_LOCAL" :
2848 (yield == HOST_FIND_AGAIN)? "HOST_FIND_AGAIN" :
2849 (yield == HOST_FIND_FAILED)? "HOST_FIND_FAILED" : "?",
2851 for (h = host; h != last->next; h = h->next)
2853 debug_printf(" %s %s MX=%d ", h->name,
2854 (h->address == NULL)? US"<null>" : h->address, h->mx);
2855 if (h->port != PORT_NONE) debug_printf("port=%d ", h->port);
2856 if (h->status >= hstatus_unusable) debug_printf("*");
2867 /*************************************************
2868 **************************************************
2869 * Stand-alone test program *
2870 **************************************************
2871 *************************************************/
2875 BOOL alldigits(uschar *buffer)
2877 if (!isdigit(*buffer)) return FALSE;
2878 if (*buffer == '0' && buffer[1] == 'x')
2881 while (isxdigit(*(++buffer)));
2883 else while (isdigit(*(++buffer)));
2884 return (*buffer == 0);
2887 int main(int argc, char **cargv)
2890 int whichrrs = HOST_FIND_BY_MX | HOST_FIND_BY_A;
2891 BOOL byname = FALSE;
2892 BOOL qualify_single = TRUE;
2893 BOOL search_parents = FALSE;
2894 uschar **argv = USS cargv;
2897 primary_hostname = US"";
2898 store_pool = POOL_MAIN;
2899 debug_selector = D_host_lookup|D_interface;
2900 debug_file = stdout;
2901 debug_fd = fileno(debug_file);
2903 printf("Exim stand-alone host functions test\n");
2905 host_find_interfaces();
2906 debug_selector = D_host_lookup | D_dns;
2908 if (argc > 1) primary_hostname = argv[1];
2910 /* So that debug level changes can be done first */
2912 dns_init(qualify_single, search_parents);
2914 printf("Testing host lookup\n");
2916 while (Ufgets(buffer, 256, stdin) != NULL)
2919 int len = Ustrlen(buffer);
2920 uschar *fully_qualified_name;
2922 while (len > 0 && isspace(buffer[len-1])) len--;
2925 if (Ustrcmp(buffer, "q") == 0) break;
2927 if (Ustrcmp(buffer, "byname") == 0) byname = TRUE;
2928 else if (Ustrcmp(buffer, "no_byname") == 0) byname = FALSE;
2929 else if (Ustrcmp(buffer, "a_only") == 0) whichrrs = HOST_FIND_BY_A;
2930 else if (Ustrcmp(buffer, "mx_only") == 0) whichrrs = HOST_FIND_BY_MX;
2931 else if (Ustrcmp(buffer, "srv_only") == 0) whichrrs = HOST_FIND_BY_SRV;
2932 else if (Ustrcmp(buffer, "srv+a") == 0)
2933 whichrrs = HOST_FIND_BY_SRV | HOST_FIND_BY_A;
2934 else if (Ustrcmp(buffer, "srv+mx") == 0)
2935 whichrrs = HOST_FIND_BY_SRV | HOST_FIND_BY_MX;
2936 else if (Ustrcmp(buffer, "srv+mx+a") == 0)
2937 whichrrs = HOST_FIND_BY_SRV | HOST_FIND_BY_MX | HOST_FIND_BY_A;
2938 else if (Ustrcmp(buffer, "qualify_single") == 0) qualify_single = TRUE;
2939 else if (Ustrcmp(buffer, "no_qualify_single") == 0) qualify_single = FALSE;
2940 else if (Ustrcmp(buffer, "search_parents") == 0) search_parents = TRUE;
2941 else if (Ustrcmp(buffer, "no_search_parents") == 0) search_parents = FALSE;
2942 else if (Ustrncmp(buffer, "retrans", 7) == 0)
2944 sscanf(CS(buffer+8), "%d", &dns_retrans);
2945 _res.retrans = dns_retrans;
2947 else if (Ustrncmp(buffer, "retry", 5) == 0)
2949 sscanf(CS(buffer+6), "%d", &dns_retry);
2950 _res.retry = dns_retry;
2952 else if (alldigits(buffer))
2954 debug_selector = Ustrtol(buffer, NULL, 0);
2955 _res.options &= ~RES_DEBUG;
2956 DEBUG(D_resolver) _res.options |= RES_DEBUG;
2960 int flags = whichrrs;
2966 h.status = hstatus_unknown;
2967 h.why = hwhy_unknown;
2970 if (qualify_single) flags |= HOST_FIND_QUALIFY_SINGLE;
2971 if (search_parents) flags |= HOST_FIND_SEARCH_PARENTS;
2974 host_find_byname(&h, NULL, &fully_qualified_name, TRUE)
2976 host_find_bydns(&h, NULL, flags, US"smtp", NULL, NULL,
2977 &fully_qualified_name, NULL);
2979 if (rc == HOST_FIND_FAILED) printf("Failed\n");
2980 else if (rc == HOST_FIND_AGAIN) printf("Again\n");
2981 else if (rc == HOST_FOUND_LOCAL) printf("Local\n");
2987 printf("Testing host_aton\n");
2989 while (Ufgets(buffer, 256, stdin) != NULL)
2993 int len = Ustrlen(buffer);
2995 while (len > 0 && isspace(buffer[len-1])) len--;
2998 if (Ustrcmp(buffer, "q") == 0) break;
3000 len = host_aton(buffer, x);
3001 printf("length = %d ", len);
3002 for (i = 0; i < len; i++)
3004 printf("%04x ", (x[i] >> 16) & 0xffff);
3005 printf("%04x ", x[i] & 0xffff);
3012 printf("Testing host_name_lookup\n");
3014 while (Ufgets(buffer, 256, stdin) != NULL)
3016 int len = Ustrlen(buffer);
3017 while (len > 0 && isspace(buffer[len-1])) len--;
3019 if (Ustrcmp(buffer, "q") == 0) break;
3020 sender_host_address = buffer;
3021 sender_host_name = NULL;
3022 sender_host_aliases = NULL;
3023 host_lookup_msg = US"";
3024 host_lookup_failed = FALSE;
3025 if (host_name_lookup() == FAIL) /* Debug causes printing */
3026 printf("Lookup failed:%s\n", host_lookup_msg);
3034 #endif /* STAND_ALONE */