1 /* $Cambridge: exim/src/src/host.c,v 1.7 2005/01/12 12:17:41 ph10 Exp $ */
3 /*************************************************
4 * Exim - an Internet mail transport agent *
5 *************************************************/
7 /* Copyright (c) University of Cambridge 1995 - 2005 */
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) == 0)
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. It may also end
739 with a "scope", introduced by a percent sign. This code is NOT enclosed in #if
740 HAVE_IPV6 in order that IPv6 addresses are recognized even if IPv6 is not
743 if (Ustrchr(address, ':') != NULL)
746 uschar *component[8];
747 BOOL ipv4_ends = FALSE;
753 /* If the address starts with a colon, it will start with two colons.
754 Just lose the first one, which will leave a null first component. */
758 /* Split the address into components separated by colons. The input address
759 is supposed to be checked for syntax. There was a case where this was
760 overlooked; to guard against that happening again, check here and crash if
761 there are too many components. */
763 while (*p != 0 && *p != '%')
765 int len = Ustrcspn(p, ":%");
766 if (len == 0) nulloffset = ci;
767 if (ci > 7) log_write(0, LOG_MAIN|LOG_PANIC_DIE,
768 "Internal error: invalid IPv6 address \"%s\" passed to host_aton()",
775 /* If the final component contains a dot, it is a trailing v4 address.
776 As the syntax is known to be checked, just set up for a trailing
777 v4 address and restrict the v6 part to 6 components. */
779 if (Ustrchr(component[ci-1], '.') != NULL)
781 address = component[--ci];
787 /* If there are fewer than 6 or 8 components, we have to insert some
788 more empty ones in the middle. */
792 int insert_count = v6count - ci;
793 for (i = v6count-1; i > nulloffset + insert_count; i--)
794 component[i] = component[i - insert_count];
795 while (i > nulloffset) component[i--] = US"";
798 /* Now turn the components into binary in pairs and bung them
799 into the vector of ints. */
801 for (i = 0; i < v6count; i += 2)
802 bin[i/2] = (Ustrtol(component[i], NULL, 16) << 16) +
803 Ustrtol(component[i+1], NULL, 16);
805 /* If there was no terminating v4 component, we are done. */
807 if (!ipv4_ends) return 4;
810 /* Handle IPv4 address */
812 sscanf(CS address, "%d.%d.%d.%d", x, x+1, x+2, x+3);
813 bin[v4offset] = (x[0] << 24) + (x[1] << 16) + (x[2] << 8) + x[3];
818 /*************************************************
819 * Apply mask to an IP address *
820 *************************************************/
822 /* Mask an address held in 1 or 4 ints, with the ms bit in the ms bit of the
826 count the number of ints
827 binary points to the ints to be masked
828 mask the count of ms bits to leave, or -1 if no masking
834 host_mask(int count, int *binary, int mask)
837 if (mask < 0) mask = 99999;
838 for (i = 0; i < count; i++)
841 if (mask == 0) wordmask = 0;
844 wordmask = (-1) << (32 - mask);
852 binary[i] &= wordmask;
859 /*************************************************
860 * Convert masked IP address in ints to text *
861 *************************************************/
863 /* We can't use host_ntoa() because it assumes the binary values are in network
864 byte order, and these are the result of host_aton(), which puts them in ints in
865 host byte order. Also, we really want IPv6 addresses to be in a canonical
866 format, so we output them with no abbreviation. In a number of cases we can't
867 use the normal colon separator in them because it terminates keys in lsearch
868 files, so we want to use dot instead. There's an argument that specifies what
869 to use for IPv6 addresses.
872 count 1 or 4 (number of ints)
873 binary points to the ints
874 mask mask value; if < 0 don't add to result
875 buffer big enough to hold the result
876 sep component separator character for IPv6 addresses
878 Returns: the number of characters placed in buffer, not counting
883 host_nmtoa(int count, int *binary, int mask, uschar *buffer, int sep)
891 for (i = 24; i >= 0; i -= 8)
893 sprintf(CS tt, "%d.", (j >> i) & 255);
899 for (i = 0; i < 4; i++)
902 sprintf(CS tt, "%04x%c%04x%c", (j >> 16) & 0xffff, sep, j & 0xffff, sep);
907 tt--; /* lose final separator */
913 sprintf(CS tt, "/%d", mask);
922 /*************************************************
923 * Check port for tls_on_connect *
924 *************************************************/
926 /* This function checks whether a given incoming port is configured for tls-
927 on-connect. It is called from the daemon and from inetd handling. If the global
928 option tls_on_connect is already set, all ports operate this way. Otherwise, we
929 check the tls_on_connect_ports option for a list of ports.
931 Argument: a port number
932 Returns: TRUE or FALSE
936 host_is_tls_on_connect_port(int port)
940 uschar *list = tls_on_connect_ports;
943 if (tls_on_connect) return TRUE;
945 while ((s = string_nextinlist(&list, &sep, buffer, sizeof(buffer))) != NULL)
948 int lport = Ustrtol(s, &end, 10);
949 if (*end != 0) log_write(0, LOG_MAIN|LOG_PANIC_DIE, "tls_on_connect_ports "
950 "contains \"%s\", which is not a port number: exim abandoned", s);
951 if (lport == port) return TRUE;
959 /*************************************************
960 * Check whether host is in a network *
961 *************************************************/
963 /* This function checks whether a given IP address matches a pattern that
964 represents either a single host, or a network (using CIDR notation). The caller
965 of this function must check the syntax of the arguments before calling it.
968 host string representation of the ip-address to check
969 net string representation of the network, with optional CIDR mask
970 maskoffset offset to the / that introduces the mask in the key
971 zero if there is no mask
974 TRUE the host is inside the network
975 FALSE the host is NOT inside the network
979 host_is_in_net(uschar *host, uschar *net, int maskoffset)
985 int size = host_aton(net, address);
988 /* No mask => all bits to be checked */
990 if (maskoffset == 0) mlen = 99999; /* Big number */
991 else mlen = Uatoi(net + maskoffset + 1);
993 /* Convert the incoming address to binary. */
995 insize = host_aton(host, incoming);
997 /* Convert IPv4 addresses given in IPv6 compatible mode, which represent
998 connections from IPv4 hosts to IPv6 hosts, that is, addresses of the form
999 ::ffff:<v4address>, to IPv4 format. */
1001 if (insize == 4 && incoming[0] == 0 && incoming[1] == 0 &&
1002 incoming[2] == 0xffff)
1005 incoming[0] = incoming[3];
1008 /* No match if the sizes don't agree. */
1010 if (insize != size) return FALSE;
1012 /* Else do the masked comparison. */
1014 for (i = 0; i < size; i++)
1017 if (mlen == 0) mask = 0;
1020 mask = (-1) << (32 - mlen);
1028 if ((incoming[i] & mask) != (address[i] & mask)) return FALSE;
1036 /*************************************************
1037 * Scan host list for local hosts *
1038 *************************************************/
1040 /* Scan through a chain of addresses and check whether any of them is the
1041 address of an interface on the local machine. If so, remove that address and
1042 any previous ones with the same MX value, and all subsequent ones (which will
1043 have greater or equal MX values) from the chain. Note: marking them as unusable
1044 is NOT the right thing to do because it causes the hosts not to be used for
1045 other domains, for which they may well be correct.
1047 The hosts may be part of a longer chain; we only process those between the
1048 initial pointer and the "last" pointer.
1050 There is also a list of "pseudo-local" host names which are checked against the
1051 host names. Any match causes that host item to be treated the same as one which
1052 matches a local IP address.
1054 If the very first host is a local host, then all MX records had a precedence
1055 greater than or equal to that of the local host. Either there's a problem in
1056 the DNS, or an apparently remote name turned out to be an abbreviation for the
1057 local host. Give a specific return code, and let the caller decide what to do.
1058 Otherwise, give a success code if at least one host address has been found.
1061 host pointer to the first host in the chain
1062 lastptr pointer to pointer to the last host in the chain (may be updated)
1063 removed if not NULL, set TRUE if some local addresses were removed
1067 HOST_FOUND if there is at least one host with an IP address on the chain
1068 and an MX value less than any MX value associated with the
1070 HOST_FOUND_LOCAL if a local host is among the lowest-numbered MX hosts; when
1071 the host addresses were obtained from A records or
1072 gethostbyname(), the MX values are set to -1.
1073 HOST_FIND_FAILED if no valid hosts with set IP addresses were found
1077 host_scan_for_local_hosts(host_item *host, host_item **lastptr, BOOL *removed)
1079 int yield = HOST_FIND_FAILED;
1080 host_item *last = *lastptr;
1081 host_item *prev = NULL;
1084 if (removed != NULL) *removed = FALSE;
1086 if (local_interface_data == NULL) local_interface_data = host_find_interfaces();
1088 for (h = host; h != last->next; h = h->next)
1091 if (hosts_treat_as_local != NULL)
1094 uschar *save = deliver_domain;
1095 deliver_domain = h->name; /* set $domain */
1096 rc = match_isinlist(string_copylc(h->name), &hosts_treat_as_local, 0,
1097 &domainlist_anchor, NULL, MCL_DOMAIN, TRUE, NULL);
1098 deliver_domain = save;
1099 if (rc == OK) goto FOUND_LOCAL;
1103 /* It seems that on many operating systems, 0.0.0.0 is treated as a synonym
1104 for 127.0.0.1 and refers to the local host. We therefore force it always to
1105 be treated as local. */
1107 if (h->address != NULL)
1109 ip_address_item *ip;
1110 if (Ustrcmp(h->address, "0.0.0.0") == 0) goto FOUND_LOCAL;
1111 for (ip = local_interface_data; ip != NULL; ip = ip->next)
1112 if (Ustrcmp(h->address, ip->address) == 0) goto FOUND_LOCAL;
1113 yield = HOST_FOUND; /* At least one remote address has been found */
1116 /* Update prev to point to the last host item before any that have
1117 the same MX value as the one we have just considered. */
1119 if (h->next == NULL || h->next->mx != h->mx) prev = h;
1122 return yield; /* No local hosts found: return HOST_FOUND or HOST_FIND_FAILED */
1124 /* A host whose IP address matches a local IP address, or whose name matches
1125 something in hosts_treat_as_local has been found. */
1131 HDEBUG(D_host_lookup) debug_printf((h->mx >= 0)?
1132 "local host has lowest MX\n" :
1133 "local host found for non-MX address\n");
1134 return HOST_FOUND_LOCAL;
1137 HDEBUG(D_host_lookup)
1139 debug_printf("local host in host list - removed hosts:\n");
1140 for (h = prev->next; h != last->next; h = h->next)
1141 debug_printf(" %s %s %d\n", h->name, h->address, h->mx);
1144 if (removed != NULL) *removed = TRUE;
1145 prev->next = last->next;
1153 /*************************************************
1154 * Remove duplicate IPs in host list *
1155 *************************************************/
1157 /* You would think that administrators could set up their DNS records so that
1158 one ended up with a list of unique IP addresses after looking up A or MX
1159 records, but apparently duplication is common. So we scan such lists and
1160 remove the later duplicates. Note that we may get lists in which some host
1161 addresses are not set.
1164 host pointer to the first host in the chain
1165 lastptr pointer to pointer to the last host in the chain (may be updated)
1171 host_remove_duplicates(host_item *host, host_item **lastptr)
1173 while (host != *lastptr)
1175 if (host->address != NULL)
1177 host_item *h = host;
1178 while (h != *lastptr)
1180 if (h->next->address != NULL &&
1181 Ustrcmp(h->next->address, host->address) == 0)
1183 DEBUG(D_host_lookup) debug_printf("duplicate IP address %s (MX=%d) "
1184 "removed\n", host->address, h->next->mx);
1185 if (h->next == *lastptr) *lastptr = h;
1186 h->next = h->next->next;
1191 /* If the last item was removed, host may have become == *lastptr */
1192 if (host != *lastptr) host = host->next;
1199 /*************************************************
1200 * Find sender host name by gethostbyaddr() *
1201 *************************************************/
1203 /* This used to be the only way it was done, but it turns out that not all
1204 systems give aliases for calls to gethostbyaddr() - or one of the modern
1205 equivalents like getipnodebyaddr(). Fortunately, multiple PTR records are rare,
1206 but they can still exist. This function is now used only when a DNS lookup of
1207 the IP address fails, in order to give access to /etc/hosts.
1210 Returns: OK, DEFER, FAIL
1214 host_name_lookup_byaddr(void)
1218 struct hostent *hosts;
1219 struct in_addr addr;
1221 /* Lookup on IPv6 system */
1224 if (Ustrchr(sender_host_address, ':') != NULL)
1226 struct in6_addr addr6;
1227 if (inet_pton(AF_INET6, CS sender_host_address, &addr6) != 1)
1228 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "unable to parse \"%s\" as an "
1229 "IPv6 address", sender_host_address);
1230 #if HAVE_GETIPNODEBYADDR
1231 hosts = getipnodebyaddr(CS &addr6, sizeof(addr6), AF_INET6, &h_errno);
1233 hosts = gethostbyaddr(CS &addr6, sizeof(addr6), AF_INET6);
1238 if (inet_pton(AF_INET, CS sender_host_address, &addr) != 1)
1239 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "unable to parse \"%s\" as an "
1240 "IPv4 address", sender_host_address);
1241 #if HAVE_GETIPNODEBYADDR
1242 hosts = getipnodebyaddr(CS &addr, sizeof(addr), AF_INET, &h_errno);
1244 hosts = gethostbyaddr(CS &addr, sizeof(addr), AF_INET);
1248 /* Do lookup on IPv4 system */
1251 addr.s_addr = (S_ADDR_TYPE)inet_addr(CS sender_host_address);
1252 hosts = gethostbyaddr(CS(&addr), sizeof(addr), AF_INET);
1255 /* Failed to look up the host. */
1259 HDEBUG(D_host_lookup) debug_printf("IP address lookup failed: h_errno=%d\n",
1261 return (h_errno == TRY_AGAIN || h_errno == NO_RECOVERY) ? DEFER : FAIL;
1264 /* It seems there are some records in the DNS that yield an empty name. We
1265 treat this as non-existent. In some operating systems, this is returned as an
1266 empty string; in others as a single dot. */
1268 if (hosts->h_name[0] == 0 || hosts->h_name[0] == '.')
1270 HDEBUG(D_host_lookup) debug_printf("IP address lookup yielded an empty name: "
1271 "treated as non-existent host name\n");
1275 /* Copy and lowercase the name, which is in static storage in many systems.
1276 Put it in permanent memory. */
1278 s = (uschar *)hosts->h_name;
1279 len = Ustrlen(s) + 1;
1280 t = sender_host_name = store_get_perm(len);
1281 while (*s != 0) *t++ = tolower(*s++);
1284 /* If the host has aliases, build a copy of the alias list */
1286 if (hosts->h_aliases != NULL)
1289 uschar **aliases, **ptr;
1290 for (aliases = USS hosts->h_aliases; *aliases != NULL; aliases++) count++;
1291 ptr = sender_host_aliases = store_get_perm(count * sizeof(uschar *));
1292 for (aliases = USS hosts->h_aliases; *aliases != NULL; aliases++)
1294 uschar *s = *aliases;
1295 int len = Ustrlen(s) + 1;
1296 uschar *t = *ptr++ = store_get_perm(len);
1297 while (*s != 0) *t++ = tolower(*s++);
1308 /*************************************************
1309 * Find host name for incoming call *
1310 *************************************************/
1312 /* Put the name in permanent store, pointed to by sender_host_name. We also set
1313 up a list of alias names, pointed to by sender_host_alias. The list is
1314 NULL-terminated. The incoming address is in sender_host_address, either in
1315 dotted-quad form for IPv4 or in colon-separated form for IPv6.
1317 This function does a thorough check that the names it finds point back to the
1318 incoming IP address. Any that do not are discarded. Note that this is relied on
1319 by the ACL reverse_host_lookup check.
1321 On some systems, get{host,ipnode}byaddr() appears to do this internally, but
1322 this it not universally true. Also, for release 4.30, this function was changed
1323 to do a direct DNS lookup first, by default[1], because it turns out that that
1324 is the only guaranteed way to find all the aliases on some systems. My
1325 experiments indicate that Solaris gethostbyaddr() gives the aliases for but
1328 [1] The actual order is controlled by the host_lookup_order option.
1331 Returns: OK on success, the answer being placed in the global variable
1332 sender_host_name, with any aliases in a list hung off
1334 FAIL if no host name can be found
1335 DEFER if a temporary error was encountered
1337 The variable host_lookup_msg is set to an empty string on sucess, or to a
1338 reason for the failure otherwise, in a form suitable for tagging onto an error
1339 message, and also host_lookup_failed is set TRUE if the lookup failed. Any
1340 dynamically constructed string for host_lookup_msg must be in permanent store,
1341 because it might be used for several incoming messages on the same SMTP
1345 host_name_lookup(void)
1349 uschar *hname, *save_hostname;
1353 uschar *list = host_lookup_order;
1358 HDEBUG(D_host_lookup)
1359 debug_printf("looking up host name for %s\n", sender_host_address);
1361 /* For testing the case when a lookup does not complete, we have a special
1362 reserved IP address. */
1364 if (running_in_test_harness &&
1365 Ustrcmp(sender_host_address, "99.99.99.99") == 0)
1367 HDEBUG(D_host_lookup)
1368 debug_printf("Test harness: host name lookup returns DEFER\n");
1372 /* Do lookups directly in the DNS or via gethostbyaddr() (or equivalent), in
1373 the order specified by the host_lookup_order option. */
1375 while ((ordername = string_nextinlist(&list, &sep, buffer, sizeof(buffer)))
1378 if (strcmpic(ordername, US"bydns") == 0)
1380 dns_init(FALSE, FALSE);
1381 dns_build_reverse(sender_host_address, buffer);
1382 rc = dns_lookup(&dnsa, buffer, T_PTR, NULL);
1384 /* The first record we come across is used for the name; others are
1385 considered to be aliases. We have to scan twice, in order to find out the
1386 number of aliases. However, if all the names are empty, we will behave as
1387 if failure. (PTR records that yield empty names have been encountered in
1390 if (rc == DNS_SUCCEED)
1392 uschar **aptr = NULL;
1395 int old_pool = store_pool;
1397 store_pool = POOL_PERM; /* Save names in permanent storage */
1399 for (rr = dns_next_rr(&dnsa, &dnss, RESET_ANSWERS);
1401 rr = dns_next_rr(&dnsa, &dnss, RESET_NEXT))
1403 if (rr->type == T_PTR) count++;
1406 /* Get store for the list of aliases. For compatibility with
1407 gethostbyaddr, we make an empty list if there are none. */
1409 aptr = sender_host_aliases = store_get(count * sizeof(uschar *));
1411 /* Re-scan and extract the names */
1413 for (rr = dns_next_rr(&dnsa, &dnss, RESET_ANSWERS);
1415 rr = dns_next_rr(&dnsa, &dnss, RESET_NEXT))
1418 if (rr->type != T_PTR) continue;
1419 s = store_get(ssize);
1421 /* If an overlong response was received, the data will have been
1422 truncated and dn_expand may fail. */
1424 if (dn_expand(dnsa.answer, dnsa.answer + dnsa.answerlen,
1425 (uschar *)(rr->data), (DN_EXPAND_ARG4_TYPE)(s), ssize) < 0)
1427 log_write(0, LOG_MAIN, "host name alias list truncated for %s",
1428 sender_host_address);
1432 store_reset(s + Ustrlen(s) + 1);
1435 HDEBUG(D_host_lookup) debug_printf("IP address lookup yielded an "
1436 "empty name: treated as non-existent host name\n");
1439 if (sender_host_name == NULL) sender_host_name = s;
1441 while (*s != 0) { *s = tolower(*s); s++; }
1444 *aptr = NULL; /* End of alias list */
1445 store_pool = old_pool; /* Reset store pool */
1447 /* If we've found a names, break out of the "order" loop */
1449 if (sender_host_name != NULL) break;
1452 /* If the DNS lookup deferred, we must also defer. */
1454 if (rc == DNS_AGAIN)
1456 HDEBUG(D_host_lookup)
1457 debug_printf("IP address PTR lookup gave temporary error\n");
1462 /* Do a lookup using gethostbyaddr() - or equivalent */
1464 else if (strcmpic(ordername, US"byaddr") == 0)
1466 HDEBUG(D_host_lookup)
1467 debug_printf("IP address lookup using gethostbyaddr()\n");
1469 rc = host_name_lookup_byaddr();
1470 if (rc == DEFER) return rc; /* Can't carry on */
1471 if (rc == OK) break; /* Found a name */
1473 } /* Loop for bydns/byaddr scanning */
1475 /* If we have failed to find a name, return FAIL and log when required.
1476 NB host_lookup_msg must be in permanent store. */
1478 if (sender_host_name == NULL)
1480 if (host_checking || !log_testing_mode)
1481 log_write(L_host_lookup_failed, LOG_MAIN, "no host name found for IP "
1482 "address %s", sender_host_address);
1483 host_lookup_msg = US" (failed to find host name from IP address)";
1485 host_lookup_failed = TRUE;
1489 /* We have a host name. If we are running in the test harness, we want the host
1490 name and its alias to appear always the same way round. There are only ever two
1491 names in these tests. If one of them contains "alias", make sure it is second;
1492 otherwise put them in alphabetical order. */
1494 if (running_in_test_harness && *sender_host_aliases != NULL &&
1496 Ustrstr(sender_host_name, "alias") != NULL ||
1498 Ustrstr(*sender_host_aliases, "alias") == NULL &&
1499 Ustrcmp(sender_host_name, *sender_host_aliases) > 0
1503 uschar *temp = sender_host_name;
1504 sender_host_name = *sender_host_aliases;
1505 *sender_host_aliases = temp;
1508 /* Debug output what was found, after test harness swapping, for consistency */
1510 HDEBUG(D_host_lookup)
1512 uschar **aliases = sender_host_aliases;
1513 debug_printf("IP address lookup yielded %s\n", sender_host_name);
1514 while (*aliases != NULL) debug_printf(" alias %s\n", *aliases++);
1517 /* We need to verify that a forward lookup on the name we found does indeed
1518 correspond to the address. This is for security: in principle a malefactor who
1519 happened to own a reverse zone could set it to point to any names at all.
1521 This code was present in versions of Exim before 3.20. At that point I took it
1522 out because I thought that gethostbyaddr() did the check anyway. It turns out
1523 that this isn't always the case, so it's coming back in at 4.01. This version
1524 is actually better, because it also checks aliases.
1526 The code was made more robust at release 4.21. Prior to that, it accepted all
1527 the names if any of them had the correct IP address. Now the code checks all
1528 the names, and accepts only those that have the correct IP address. */
1530 save_hostname = sender_host_name; /* Save for error messages */
1531 aliases = sender_host_aliases;
1532 for (hname = sender_host_name; hname != NULL; hname = *aliases++)
1542 /* When called with the 5th argument FALSE, host_find_byname() won't return
1543 HOST_FOUND_LOCAL. If the incoming address is an IPv4 address expressed in
1544 IPv6 format, we must compare the IPv4 part to any IPv4 addresses. */
1546 if ((rc = host_find_byname(&h, NULL, NULL, FALSE)) == HOST_FOUND)
1549 uschar *address_ipv4 = (Ustrncmp(sender_host_address, "::ffff:", 7) == 0)?
1550 sender_host_address + 7 : sender_host_address;
1551 HDEBUG(D_host_lookup) debug_printf("checking addresses for %s\n", hname);
1552 for (hh = &h; hh != NULL; hh = hh->next)
1554 if ((Ustrcmp(hh->address, (Ustrchr(hh->address, ':') == NULL)?
1555 address_ipv4 : sender_host_address)) == 0)
1557 HDEBUG(D_host_lookup) debug_printf(" %s OK\n", hh->address);
1563 HDEBUG(D_host_lookup) debug_printf(" %s\n", hh->address);
1566 if (!ok) HDEBUG(D_host_lookup)
1567 debug_printf("no IP address for %s matched %s\n", hname,
1568 sender_host_address);
1570 else if (rc == HOST_FIND_AGAIN)
1572 HDEBUG(D_host_lookup) debug_printf("temporary error for host name lookup\n");
1577 HDEBUG(D_host_lookup) debug_printf("no IP addresses found for %s\n", hname);
1580 /* If this name is no good, and it's the sender name, set it null pro tem;
1581 if it's an alias, just remove it from the list. */
1585 if (hname == sender_host_name) sender_host_name = NULL; else
1587 uschar **a; /* Don't amalgamate - some */
1588 a = --aliases; /* compilers grumble */
1589 while (*a != NULL) { *a = a[1]; a++; }
1594 /* If sender_host_name == NULL, it means we didn't like the name. Replace
1595 it with the first alias, if there is one. */
1597 if (sender_host_name == NULL && *sender_host_aliases != NULL)
1598 sender_host_name = *sender_host_aliases++;
1600 /* If we now have a main name, all is well. */
1602 if (sender_host_name != NULL) return OK;
1604 /* We have failed to find an address that matches. */
1606 HDEBUG(D_host_lookup)
1607 debug_printf("%s does not match any IP address for %s\n",
1608 sender_host_address, save_hostname);
1610 /* This message must be in permanent store */
1612 old_pool = store_pool;
1613 store_pool = POOL_PERM;
1614 host_lookup_msg = string_sprintf(" (%s does not match any IP address for %s)",
1615 sender_host_address, save_hostname);
1616 store_pool = old_pool;
1618 host_lookup_failed = TRUE;
1625 /*************************************************
1626 * Find IP address(es) for host by name *
1627 *************************************************/
1629 /* The input is a host_item structure with the name filled in and the address
1630 field set to NULL. We use gethostbyname(). Of course, gethostbyname() may use
1631 the DNS, but it doesn't do MX processing. If more than one address is given,
1632 chain on additional host items, with other relevant fields copied.
1634 The second argument provides a host list (usually an IP list) of hosts to
1635 ignore. This makes it possible to ignore IPv6 link-local addresses or loopback
1636 addresses in unreasonable places.
1638 The lookup may result in a change of name. For compatibility with the dns
1639 lookup, return this via fully_qualified_name as well as updating the host item.
1640 The lookup may also yield more than one IP address, in which case chain on
1641 subsequent host_item structures.
1644 host a host item with the name and MX filled in;
1645 the address is to be filled in;
1646 multiple IP addresses cause other host items to be
1648 ignore_target_hosts a list of hosts to ignore
1649 fully_qualified_name if not NULL, set to point to host name for
1650 compatibility with host_find_bydns
1651 local_host_check TRUE if a check for the local host is wanted
1653 Returns: HOST_FIND_FAILED Failed to find the host or domain
1654 HOST_FIND_AGAIN Try again later
1655 HOST_FOUND Host found - data filled in
1656 HOST_FOUND_LOCAL Host found and is the local host
1660 host_find_byname(host_item *host, uschar *ignore_target_hosts,
1661 uschar **fully_qualified_name, BOOL local_host_check)
1663 int i, yield, times;
1665 host_item *last = NULL;
1666 BOOL temp_error = FALSE;
1668 /* In an IPv6 world, we need to scan for both kinds of address, so go round the
1669 loop twice. Note that we have ensured that AF_INET6 is defined even in an IPv4
1670 world, which makes for slightly tidier code. However, if dns_ipv4_lookup
1671 matches the domain, we also just do IPv4 lookups here (except when testing
1678 if (dns_ipv4_lookup != NULL &&
1679 match_isinlist(host->name, &dns_ipv4_lookup, 0, NULL, NULL, MCL_DOMAIN,
1681 { af = AF_INET; times = 1; }
1683 #endif /* STAND_ALONE */
1685 { af = AF_INET6; times = 2; }
1687 /* No IPv6 support */
1689 #else /* HAVE_IPV6 */
1691 #endif /* HAVE_IPV6 */
1693 /* Initialize the flag that gets set for DNS syntax check errors, so that the
1694 interface to this function can be similar to host_find_bydns. */
1696 host_find_failed_syntax = FALSE;
1698 /* Loop to look up both kinds of address in an IPv6 world */
1700 for (i = 1; i <= times;
1702 af = AF_INET, /* If 2 passes, IPv4 on the second */
1708 struct hostent *hostdata;
1711 #if HAVE_GETIPNODEBYNAME
1712 hostdata = getipnodebyname(CS host->name, af, 0, &error_num);
1714 hostdata = gethostbyname2(CS host->name, af);
1715 error_num = h_errno;
1718 hostdata = gethostbyname(CS host->name);
1719 error_num = h_errno;
1722 if (hostdata == NULL)
1727 case HOST_NOT_FOUND: error = US"HOST_NOT_FOUND"; break;
1728 case TRY_AGAIN: error = US"TRY_AGAIN"; break;
1729 case NO_RECOVERY: error = US"NO_RECOVERY"; break;
1730 case NO_DATA: error = US"NO_DATA"; break;
1731 #if NO_DATA != NO_ADDRESS
1732 case NO_ADDRESS: error = US"NO_ADDRESS"; break;
1734 default: error = US"?"; break;
1737 DEBUG(D_host_lookup) debug_printf("%s returned %d (%s)\n",
1739 #if HAVE_GETIPNODEBYNAME
1740 (af == AF_INET6)? "getipnodebyname(af=inet6)" : "getipnodebyname(af=inet)",
1742 (af == AF_INET6)? "gethostbyname2(af=inet6)" : "gethostbyname2(af=inet)",
1749 if (error_num == TRY_AGAIN || error_num == NO_RECOVERY) temp_error = TRUE;
1752 if ((hostdata->h_addr_list)[0] == NULL) continue;
1754 /* Replace the name with the fully qualified one if necessary, and fill in
1755 the fully_qualified_name pointer. */
1757 if (hostdata->h_name[0] != 0 &&
1758 Ustrcmp(host->name, hostdata->h_name) != 0)
1759 host->name = string_copy_dnsdomain((uschar *)hostdata->h_name);
1760 if (fully_qualified_name != NULL) *fully_qualified_name = host->name;
1762 /* Get the list of addresses. IPv4 and IPv6 addresses can be distinguished
1763 by their different lengths. Scan the list, ignoring any that are to be
1764 ignored, and build a chain from the rest. */
1766 ipv4_addr = hostdata->h_length == sizeof(struct in_addr);
1768 for (addrlist = USS hostdata->h_addr_list; *addrlist != NULL; addrlist++)
1770 uschar *text_address =
1771 host_ntoa(ipv4_addr? AF_INET:AF_INET6, *addrlist, NULL, NULL);
1774 if (ignore_target_hosts != NULL &&
1775 verify_check_this_host(&ignore_target_hosts, NULL, host->name,
1776 text_address, NULL) == OK)
1778 DEBUG(D_host_lookup)
1779 debug_printf("ignored host %s [%s]\n", host->name, text_address);
1784 /* If this is the first address, last == NULL and we put the data in the
1789 host->address = text_address;
1790 host->port = PORT_NONE;
1791 host->status = hstatus_unknown;
1792 host->why = hwhy_unknown;
1796 /* Else add further host item blocks for any other addresses, keeping
1801 host_item *next = store_get(sizeof(host_item));
1802 next->name = host->name;
1803 next->mx = host->mx;
1804 next->address = text_address;
1805 next->port = PORT_NONE;
1806 next->status = hstatus_unknown;
1807 next->why = hwhy_unknown;
1809 next->next = last->next;
1816 /* If no hosts were found, the address field in the original host block will be
1817 NULL. If temp_error is set, at least one of the lookups gave a temporary error,
1818 so we pass that back. */
1820 if (host->address == NULL)
1824 (message_id[0] == 0 && smtp_in != NULL)?
1825 string_sprintf("no IP address found for host %s (during %s)", host->name,
1826 smtp_get_connection_info()) :
1828 string_sprintf("no IP address found for host %s", host->name);
1830 HDEBUG(D_host_lookup) debug_printf("%s\n", msg);
1831 if (temp_error) return HOST_FIND_AGAIN;
1832 if (host_checking || !log_testing_mode)
1833 log_write(L_host_lookup_failed, LOG_MAIN, "%s", msg);
1834 return HOST_FIND_FAILED;
1837 /* Remove any duplicate IP addresses, then check to see if this is the local
1838 host if required. */
1840 host_remove_duplicates(host, &last);
1841 yield = local_host_check?
1842 host_scan_for_local_hosts(host, &last, NULL) : HOST_FOUND;
1844 /* When running in the test harness, sort into the order of addresses so as to
1845 get repeatability. */
1847 if (running_in_test_harness) sort_addresses(host, last);
1849 HDEBUG(D_host_lookup)
1852 if (fully_qualified_name != NULL)
1853 debug_printf("fully qualified name = %s\n", *fully_qualified_name);
1854 debug_printf("%s looked up these IP addresses:\n",
1856 #if HAVE_GETIPNODEBYNAME
1865 for (h = host; h != last->next; h = h->next)
1866 debug_printf(" name=%s address=%s\n", h->name,
1867 (h->address == NULL)? US"<null>" : h->address);
1870 /* Return the found status. */
1877 /*************************************************
1878 * Fill in a host address from the DNS *
1879 *************************************************/
1881 /* Given a host item, with its name and mx fields set, and its address field
1882 set to NULL, fill in its IP address from the DNS. If it is multi-homed, create
1883 additional host items for the additional addresses, copying all the other
1884 fields, and randomizing the order.
1886 On IPv6 systems, A6 records are sought first (but only if support for A6 is
1887 configured - they may never become mainstream), then AAAA records are sought,
1888 and finally A records are sought as well.
1890 The host name may be changed if the DNS returns a different name - e.g. fully
1891 qualified or changed via CNAME. If fully_qualified_name is not NULL, dns_lookup
1892 ensures that it points to the fully qualified name. However, this is the fully
1893 qualified version of the original name; if a CNAME is involved, the actual
1894 canonical host name may be different again, and so we get it directly from the
1895 relevant RR. Note that we do NOT change the mx field of the host item in this
1896 function as it may be called to set the addresses of hosts taken from MX
1900 host points to the host item we're filling in
1901 lastptr points to pointer to last host item in a chain of
1902 host items (may be updated if host is last and gets
1903 extended because multihomed)
1904 ignore_target_hosts list of hosts to ignore
1905 allow_ip if TRUE, recognize an IP address and return it
1906 fully_qualified_name if not NULL, return fully qualified name here if
1907 the contents are different (i.e. it must be preset
1910 Returns: HOST_FIND_FAILED couldn't find A record
1911 HOST_FIND_AGAIN try again later
1912 HOST_FOUND found AAAA and/or A record(s)
1913 HOST_IGNORED found, but all IPs ignored
1917 set_address_from_dns(host_item *host, host_item **lastptr,
1918 uschar *ignore_target_hosts, BOOL allow_ip, uschar **fully_qualified_name)
1921 host_item *thishostlast = NULL; /* Indicates not yet filled in anything */
1922 BOOL v6_find_again = FALSE;
1925 /* If allow_ip is set, a name which is an IP address returns that value
1926 as its address. This is used for MX records when allow_mx_to_ip is set, for
1927 those sites that feel they have to flaunt the RFC rules. */
1929 if (allow_ip && string_is_ip_address(host->name, NULL) != 0)
1932 if (ignore_target_hosts != NULL &&
1933 verify_check_this_host(&ignore_target_hosts, NULL, host->name,
1934 host->name, NULL) == OK)
1935 return HOST_IGNORED;
1938 host->address = host->name;
1939 host->port = PORT_NONE;
1943 /* On an IPv6 system, go round the loop up to three times, looking for A6 and
1944 AAAA records the first two times. However, unless doing standalone testing, we
1945 force an IPv4 lookup if the domain matches dns_ipv4_lookup is set. Since A6
1946 records look like being abandoned, support them only if explicitly configured
1947 to do so. On an IPv4 system, go round the loop once only, looking only for A
1953 if (dns_ipv4_lookup != NULL &&
1954 match_isinlist(host->name, &dns_ipv4_lookup, 0, NULL, NULL, MCL_DOMAIN,
1956 i = 0; /* look up A records only */
1958 #endif /* STAND_ALONE */
1961 i = 2; /* look up A6 and AAAA and A records */
1963 i = 1; /* look up AAAA and A records */
1964 #endif /* SUPPORT_A6 */
1966 /* The IPv4 world */
1968 #else /* HAVE_IPV6 */
1969 i = 0; /* look up A records only */
1970 #endif /* HAVE_IPV6 */
1974 static int types[] = { T_A, T_AAAA, T_A6 };
1975 int type = types[i];
1976 int randoffset = (i == 0)? 500 : 0; /* Ensures v6 sorts before v4 */
1980 int rc = dns_lookup(&dnsa, host->name, type, fully_qualified_name);
1982 /* We want to return HOST_FIND_AGAIN if one of the A, A6, or AAAA lookups
1983 fails or times out, but not if another one succeeds. (In the early
1984 IPv6 days there are name servers that always fail on AAAA, but are happy
1985 to give out an A record. We want to proceed with that A record.) */
1987 if (rc != DNS_SUCCEED)
1989 if (i == 0) /* Just tried for an A record, i.e. end of loop */
1991 if (host->address != NULL) return HOST_FOUND; /* A6 or AAAA was found */
1992 if (rc == DNS_AGAIN || rc == DNS_FAIL || v6_find_again)
1993 return HOST_FIND_AGAIN;
1994 return HOST_FIND_FAILED; /* DNS_NOMATCH or DNS_NODATA */
1997 /* Tried for an A6 or AAAA record: remember if this was a temporary
1998 error, and look for the next record type. */
2000 if (rc != DNS_NOMATCH && rc != DNS_NODATA) v6_find_again = TRUE;
2004 /* Lookup succeeded: fill in the given host item with the first non-ignored
2005 address found; create additional items for any others. A single A6 record
2006 may generate more than one address. */
2008 for (rr = dns_next_rr(&dnsa, &dnss, RESET_ANSWERS);
2010 rr = dns_next_rr(&dnsa, &dnss, RESET_NEXT))
2012 if (rr->type == type)
2014 /* dns_address *da = dns_address_from_rr(&dnsa, rr); */
2017 da = dns_address_from_rr(&dnsa, rr);
2019 DEBUG(D_host_lookup)
2022 debug_printf("no addresses extracted from A6 RR for %s\n",
2026 /* This loop runs only once for A and AAAA records, but may run
2027 several times for an A6 record that generated multiple addresses. */
2029 for (; da != NULL; da = da->next)
2032 if (ignore_target_hosts != NULL &&
2033 verify_check_this_host(&ignore_target_hosts, NULL,
2034 host->name, da->address, NULL) == OK)
2036 DEBUG(D_host_lookup)
2037 debug_printf("ignored host %s [%s]\n", host->name, da->address);
2042 /* If this is the first address, stick it in the given host block,
2043 and change the name if the returned RR has a different name. */
2045 if (thishostlast == NULL)
2047 if (strcmpic(host->name, rr->name) != 0)
2048 host->name = string_copy_dnsdomain(rr->name);
2049 host->address = da->address;
2050 host->port = PORT_NONE;
2051 host->sort_key = host->mx * 1000 + random_number(500) + randoffset;
2052 host->status = hstatus_unknown;
2053 host->why = hwhy_unknown;
2054 thishostlast = host;
2057 /* Not the first address. Check for, and ignore, duplicates. Then
2058 insert in the chain at a random point. */
2065 /* End of our local chain is specified by "thishostlast". */
2067 for (next = host;; next = next->next)
2069 if (Ustrcmp(CS da->address, next->address) == 0) break;
2070 if (next == thishostlast) { next = NULL; break; }
2072 if (next != NULL) continue; /* With loop for next address */
2074 /* Not a duplicate */
2076 new_sort_key = host->mx * 1000 + random_number(500) + randoffset;
2077 next = store_get(sizeof(host_item));
2079 /* New address goes first: insert the new block after the first one
2080 (so as not to disturb the original pointer) but put the new address
2081 in the original block. */
2083 if (new_sort_key < host->sort_key)
2087 host->address = da->address;
2088 host->port = PORT_NONE;
2089 host->sort_key = new_sort_key;
2090 if (thishostlast == host) thishostlast = next; /* Local last */
2091 if (*lastptr == host) *lastptr = next; /* Global last */
2094 /* Otherwise scan down the addresses for this host to find the
2095 one to insert after. */
2099 host_item *h = host;
2100 while (h != thishostlast)
2102 if (new_sort_key < h->next->sort_key) break;
2107 next->address = da->address;
2108 next->port = PORT_NONE;
2109 next->sort_key = new_sort_key;
2110 if (h == thishostlast) thishostlast = next; /* Local last */
2111 if (h == *lastptr) *lastptr = next; /* Global last */
2119 /* Control gets here only if the third lookup (the A record) succeeded.
2120 However, the address may not be filled in if it was ignored. */
2122 return (host->address == NULL)? HOST_IGNORED : HOST_FOUND;
2128 /*************************************************
2129 * Find IP addresses and names for host via DNS *
2130 *************************************************/
2132 /* The input is a host_item structure with the name filled in and the address
2133 field set to NULL. This may be in a chain of other host items. The lookup may
2134 result in more than one IP address, in which case we must created new host
2135 blocks for the additional addresses, and insert them into the chain. The
2136 original name may not be fully qualified. Use the fully_qualified_name argument
2137 to return the official name, as returned by the resolver.
2140 host point to initial host item
2141 ignore_target_hosts a list of hosts to ignore
2142 whichrrs flags indicating which RRs to look for:
2143 HOST_FIND_BY_SRV => look for SRV
2144 HOST_FIND_BY_MX => look for MX
2145 HOST_FIND_BY_A => look for A or AAAA
2146 also flags indicating how the lookup is done
2147 HOST_FIND_QUALIFY_SINGLE ) passed to the
2148 HOST_FIND_SEARCH_PARENTS ) resolver
2149 srv_service when SRV used, the service name
2150 srv_fail_domains DNS errors for these domains => assume nonexist
2151 mx_fail_domains DNS errors for these domains => assume nonexist
2152 fully_qualified_name if not NULL, return fully-qualified name
2153 removed set TRUE if local host was removed from the list
2155 Returns: HOST_FIND_FAILED Failed to find the host or domain;
2156 if there was a syntax error,
2157 host_find_failed_syntax is set.
2158 HOST_FIND_AGAIN Could not resolve at this time
2159 HOST_FOUND Host found
2160 HOST_FOUND_LOCAL The lowest MX record points to this
2161 machine, if MX records were found, or
2162 an A record that was found contains
2163 an address of the local host
2167 host_find_bydns(host_item *host, uschar *ignore_target_hosts, int whichrrs,
2168 uschar *srv_service, uschar *srv_fail_domains, uschar *mx_fail_domains,
2169 uschar **fully_qualified_name, BOOL *removed)
2171 host_item *h, *last;
2179 /* Set the default fully qualified name to the incoming name, initialize the
2180 resolver if necessary, set up the relevant options, and initialize the flag
2181 that gets set for DNS syntax check errors. */
2183 if (fully_qualified_name != NULL) *fully_qualified_name = host->name;
2184 dns_init((whichrrs & HOST_FIND_QUALIFY_SINGLE) != 0,
2185 (whichrrs & HOST_FIND_SEARCH_PARENTS) != 0);
2186 host_find_failed_syntax = FALSE;
2188 /* First, if requested, look for SRV records. The service name is given; we
2189 assume TCP progocol. DNS domain names are constrained to a maximum of 256
2190 characters, so the code below should be safe. */
2192 if ((whichrrs & HOST_FIND_BY_SRV) != 0)
2195 uschar *temp_fully_qualified_name = buffer;
2198 (void)sprintf(CS buffer, "_%s._tcp.%n%.256s", srv_service, &prefix_length,
2202 /* Search for SRV records. If the fully qualified name is different to
2203 the input name, pass back the new original domain, without the prepended
2206 rc = dns_lookup(&dnsa, buffer, ind_type, &temp_fully_qualified_name);
2207 if (temp_fully_qualified_name != buffer && fully_qualified_name != NULL)
2208 *fully_qualified_name = temp_fully_qualified_name + prefix_length;
2210 /* On DNS failures, we give the "try again" error unless the domain is
2211 listed as one for which we continue. */
2213 if (rc == DNS_FAIL || rc == DNS_AGAIN)
2215 if (match_isinlist(host->name, &srv_fail_domains, 0, NULL, NULL, MCL_DOMAIN,
2217 return HOST_FIND_AGAIN;
2218 DEBUG(D_host_lookup) debug_printf("DNS_%s treated as DNS_NODATA "
2219 "(domain in srv_fail_domains)\n", (rc == DNS_FAIL)? "FAIL":"AGAIN");
2223 /* If we did not find any SRV records, search the DNS for MX records, if
2224 requested to do so. If the result is DNS_NOMATCH, it means there is no such
2225 domain, and there's no point in going on to look for address records with the
2226 same domain. The result will be DNS_NODATA if the domain exists but has no MX
2227 records. On DNS failures, we give the "try again" error unless the domain is
2228 listed as one for which we continue. */
2230 if (rc != DNS_SUCCEED && (whichrrs & HOST_FIND_BY_MX) != 0)
2233 rc = dns_lookup(&dnsa, host->name, ind_type, fully_qualified_name);
2234 if (rc == DNS_NOMATCH) return HOST_FIND_FAILED;
2235 if (rc == DNS_FAIL || rc == DNS_AGAIN)
2237 if (match_isinlist(host->name, &mx_fail_domains, 0, NULL, NULL, MCL_DOMAIN,
2239 return HOST_FIND_AGAIN;
2240 DEBUG(D_host_lookup) debug_printf("DNS_%s treated as DNS_NODATA "
2241 "(domain in mx_fail_domains)\n", (rc == DNS_FAIL)? "FAIL":"AGAIN");
2245 /* If we haven't found anything yet, and we are requested to do so, try for an
2246 A or AAAA record. If we find it (or them) check to see that it isn't the local
2249 if (rc != DNS_SUCCEED)
2251 if ((whichrrs & HOST_FIND_BY_A) == 0)
2253 DEBUG(D_host_lookup) debug_printf("Address records are not being sought\n");
2254 return HOST_FIND_FAILED;
2257 last = host; /* End of local chainlet */
2259 host->port = PORT_NONE;
2260 rc = set_address_from_dns(host, &last, ignore_target_hosts, FALSE,
2261 fully_qualified_name);
2263 /* If one or more address records have been found, check that none of them
2264 are local. Since we know the host items all have their IP addresses
2265 inserted, host_scan_for_local_hosts() can only return HOST_FOUND or
2266 HOST_FOUND_LOCAL. We do not need to scan for duplicate IP addresses here,
2267 because set_address_from_dns() removes them. */
2269 if (rc == HOST_FOUND)
2270 rc = host_scan_for_local_hosts(host, &last, removed);
2272 if (rc == HOST_IGNORED) rc = HOST_FIND_FAILED; /* No special action */
2274 /* When running in the test harness, sort into the order of addresses so as
2275 to get repeatability. */
2277 if (running_in_test_harness) sort_addresses(host, last);
2279 DEBUG(D_host_lookup)
2282 if (host->address != NULL)
2284 if (fully_qualified_name != NULL)
2285 debug_printf("fully qualified name = %s\n", *fully_qualified_name);
2286 for (h = host; h != last->next; h = h->next)
2287 debug_printf("%s %s mx=%d sort=%d %s\n", h->name,
2288 (h->address == NULL)? US"<null>" : h->address, h->mx, h->sort_key,
2289 (h->status >= hstatus_unusable)? US"*" : US"");
2296 /* We have found one or more MX or SRV records. Sort them according to
2297 precedence. Put the data for the first one into the existing host block, and
2298 insert new host_item blocks into the chain for the remainder. For equal
2299 precedences one is supposed to randomize the order. To make this happen, the
2300 sorting is actually done on the MX value * 1000 + a random number. This is put
2301 into a host field called sort_key.
2303 In the case of hosts with both IPv6 and IPv4 addresses, we want to choose the
2304 IPv6 address in preference. At this stage, we don't know what kind of address
2305 the host has. We choose a random number < 500; if later we find an A record
2306 first, we add 500 to the random number. Then for any other address records, we
2307 use random numbers in the range 0-499 for AAAA records and 500-999 for A
2310 At this point we remove any duplicates that point to the same host, retaining
2311 only the one with the lowest precedence. We cannot yet check for precedence
2312 greater than that of the local host, because that test cannot be properly done
2313 until the addresses have been found - an MX record may point to a name for this
2314 host which is not the primary hostname. */
2316 last = NULL; /* Indicates that not even the first item is filled yet */
2318 for (rr = dns_next_rr(&dnsa, &dnss, RESET_ANSWERS);
2320 rr = dns_next_rr(&dnsa, &dnss, RESET_NEXT))
2323 int weight = 0; /* For SRV records */
2324 int port = PORT_NONE; /* For SRV records */
2325 uschar *s; /* MUST be unsigned for GETSHORT */
2328 if (rr->type != ind_type) continue;
2330 GETSHORT(precedence, s); /* Pointer s is advanced */
2332 /* For MX records, we use a random "weight" which causes multiple records of
2333 the same precedence to sort randomly. */
2335 if (ind_type == T_MX)
2337 weight = random_number(500);
2340 /* SRV records are specified with a port and a weight. The weight is used
2341 in a special algorithm. However, to start with, we just use it to order the
2342 records of equal priority (precedence). */
2346 GETSHORT(weight, s);
2350 /* Get the name of the host pointed to. */
2352 (void)dn_expand(dnsa.answer, dnsa.answer + dnsa.answerlen, s,
2353 (DN_EXPAND_ARG4_TYPE)data, sizeof(data));
2355 /* Check that we haven't already got this host on the chain; if we have,
2356 keep only the lower precedence. This situation shouldn't occur, but you
2357 never know what junk might get into the DNS (and this case has been seen on
2358 more than one occasion). */
2360 if (last != NULL) /* This is not the first record */
2362 host_item *prev = NULL;
2364 for (h = host; h != last->next; prev = h, h = h->next)
2366 if (strcmpic(h->name, data) == 0)
2368 DEBUG(D_host_lookup)
2369 debug_printf("discarded duplicate host %s (MX=%d)\n", data,
2370 (precedence > h->mx)? precedence : h->mx);
2371 if (precedence >= h->mx) goto NEXT_MX_RR; /* Skip greater precedence */
2372 if (h == host) /* Override first item */
2375 host->sort_key = precedence * 1000 + weight;
2379 /* Unwanted host item is not the first in the chain, so we can get
2380 get rid of it by cutting it out. */
2382 prev->next = h->next;
2383 if (h == last) last = prev;
2389 /* If this is the first MX or SRV record, put the data into the existing host
2390 block. Otherwise, add a new block in the correct place; if it has to be
2391 before the first block, copy the first block's data to a new second block. */
2395 host->name = string_copy_dnsdomain(data);
2396 host->address = NULL;
2398 host->mx = precedence;
2399 host->sort_key = precedence * 1000 + weight;
2400 host->status = hstatus_unknown;
2401 host->why = hwhy_unknown;
2405 /* Make a new host item and seek the correct insertion place */
2409 int sort_key = precedence * 1000 + weight;
2410 host_item *next = store_get(sizeof(host_item));
2411 next->name = string_copy_dnsdomain(data);
2412 next->address = NULL;
2414 next->mx = precedence;
2415 next->sort_key = sort_key;
2416 next->status = hstatus_unknown;
2417 next->why = hwhy_unknown;
2420 /* Handle the case when we have to insert before the first item. */
2422 if (sort_key < host->sort_key)
2429 if (last == host) last = next;
2432 /* Else scan down the items we have inserted as part of this exercise;
2433 don't go further. */
2437 for (h = host; h != last; h = h->next)
2439 if (sort_key < h->next->sort_key)
2441 next->next = h->next;
2447 /* Join on after the last host item that's part of this
2448 processing if we haven't stopped sooner. */
2452 next->next = last->next;
2459 NEXT_MX_RR: continue;
2462 /* If the list of hosts was obtained from SRV records, there are two things to
2463 do. First, if there is only one host, and it's name is ".", it means there is
2464 no SMTP service at this domain. Otherwise, we have to sort the hosts of equal
2465 priority according to their weights, using an algorithm that is defined in RFC
2466 2782. The hosts are currently sorted by priority and weight. For each priority
2467 group we have to pick off one host and put it first, and then repeat for any
2468 remaining in the same priority group. */
2470 if (ind_type == T_SRV)
2474 if (host == last && host->name[0] == 0)
2476 DEBUG(D_host_lookup) debug_printf("the single SRV record is \".\"\n");
2477 return HOST_FIND_FAILED;
2480 DEBUG(D_host_lookup)
2482 debug_printf("original ordering of hosts from SRV records:\n");
2483 for (h = host; h != last->next; h = h->next)
2484 debug_printf(" %s P=%d W=%d\n", h->name, h->mx, h->sort_key % 1000);
2487 for (pptr = &host, h = host; h != last; pptr = &(h->next), h = h->next)
2492 /* Find the last following host that has the same precedence. At the same
2493 time, compute the sum of the weights and the running totals. These can be
2494 stored in the sort_key field. */
2496 for (hh = h; hh != last; hh = hh->next)
2498 int weight = hh->sort_key % 1000; /* was precedence * 1000 + weight */
2501 if (hh->mx != hh->next->mx) break;
2504 /* If there's more than one host at this precedence (priority), we need to
2505 pick one to go first. */
2511 int randomizer = random_number(sum + 1);
2513 for (ppptr = pptr, hhh = h;
2515 ppptr = &(hhh->next), hhh = hhh->next)
2517 if (hhh->sort_key >= randomizer) break;
2520 /* hhh now points to the host that should go first; ppptr points to the
2521 place that points to it. Unfortunately, if the start of the minilist is
2522 the start of the entire list, we can't just swap the items over, because
2523 we must not change the value of host, since it is passed in from outside.
2524 One day, this could perhaps be changed.
2526 The special case is fudged by putting the new item *second* in the chain,
2527 and then transferring the data between the first and second items. We
2528 can't just swap the first and the chosen item, because that would mean
2529 that an item with zero weight might no longer be first. */
2533 *ppptr = hhh->next; /* Cuts it out of the chain */
2537 host_item temp = *h;
2540 hhh->next = temp.next;
2546 hhh->next = h; /* The rest of the chain follows it */
2547 *pptr = hhh; /* It takes the place of h */
2548 h = hhh; /* It's now the start of this minilist */
2553 /* A host has been chosen to be first at this priority and h now points
2554 to this host. There may be others at the same priority, or others at a
2555 different priority. Before we leave this host, we need to put back a sort
2556 key of the traditional MX kind, in case this host is multihomed, because
2557 the sort key is used for ordering the multiple IP addresses. We do not need
2558 to ensure that these new sort keys actually reflect the order of the hosts,
2561 h->sort_key = h->mx * 1000 + random_number(500);
2562 } /* Move on to the next host */
2565 /* Now we have to ensure addresses exist for all the hosts. We have ensured
2566 above that the names in the host items are all unique. The addresses may have
2567 been returned in the additional data section of the DNS query. Because it is
2568 more expensive to scan the returned DNS records (because you have to expand the
2569 names) we do a single scan over them, and multiple scans of the chain of host
2570 items (which is typically only 3 or 4 long anyway.) Add extra host items for
2571 multi-homed hosts. */
2573 for (rr = dns_next_rr(&dnsa, &dnss, RESET_ADDITIONAL);
2575 rr = dns_next_rr(&dnsa, &dnss, RESET_NEXT))
2578 int status = hstatus_unknown;
2579 int why = hwhy_unknown;
2584 && rr->type != T_AAAA
2591 /* Find the first host that matches this record's name. If there isn't
2592 one, move on to the next RR. */
2594 for (h = host; h != last->next; h = h->next)
2595 { if (strcmpic(h->name, rr->name) == 0) break; }
2596 if (h == last->next) continue;
2598 /* For IPv4 addresses, add 500 to the random part of the sort key, to ensure
2599 they sort after IPv6 addresses. */
2601 randoffset = (rr->type == T_A)? 500 : 0;
2603 /* Get the list of textual addresses for this RR. There may be more than one
2604 if it is an A6 RR. Then loop to handle multiple addresses from an A6 record.
2605 If there are none, nothing will get done - the record is ignored. */
2607 for (da = dns_address_from_rr(&dnsa, rr); da != NULL; da = da->next)
2609 /* Set status for an ignorable host. */
2612 if (ignore_target_hosts != NULL &&
2613 verify_check_this_host(&ignore_target_hosts, NULL, h->name,
2614 da->address, NULL) == OK)
2616 DEBUG(D_host_lookup)
2617 debug_printf("ignored host %s [%s]\n", h->name, da->address);
2618 status = hstatus_unusable;
2623 /* If the address is already set for this host, it may be that
2624 we just have a duplicate DNS record. Alternatively, this may be
2625 a multi-homed host. Search all items with the same host name
2626 (they will all be together) and if this address is found, skip
2629 if (h->address != NULL)
2632 host_item *thishostlast;
2637 if (hh->address != NULL && Ustrcmp(CS da->address, hh->address) == 0)
2638 goto DNS_NEXT_RR; /* Need goto to escape from inner loop */
2642 while (hh != last->next && strcmpic(hh->name, rr->name) == 0);
2644 /* We have a multi-homed host, since we have a new address for
2645 an existing name. Create a copy of the current item, and give it
2646 the new address. RRs can be in arbitrary order, but one is supposed
2647 to randomize the addresses of multi-homed hosts, so compute a new
2648 sorting key and do that. [Latest SMTP RFC says not to randomize multi-
2649 homed hosts, but to rely on the resolver. I'm not happy about that -
2650 caching in the resolver will not rotate as often as the name server
2653 new_sort_key = h->mx * 1000 + random_number(500) + randoffset;
2654 hh = store_get(sizeof(host_item));
2656 /* New address goes first: insert the new block after the first one
2657 (so as not to disturb the original pointer) but put the new address
2658 in the original block. */
2660 if (new_sort_key < h->sort_key)
2662 *hh = *h; /* Note: copies the port */
2664 h->address = da->address;
2665 h->sort_key = new_sort_key;
2670 /* Otherwise scan down the addresses for this host to find the
2671 one to insert after. */
2675 while (h != thishostlast)
2677 if (new_sort_key < h->next->sort_key) break;
2680 *hh = *h; /* Note: copies the port */
2682 hh->address = da->address;
2683 hh->sort_key = new_sort_key;
2684 hh->status = status;
2688 if (h == last) last = hh; /* Inserted after last */
2691 /* The existing item doesn't have its address set yet, so just set it.
2692 Ensure that an IPv4 address gets its sort key incremented in case an IPv6
2693 address is found later. */
2697 h->address = da->address; /* Port should be set already */
2700 h->sort_key += randoffset;
2702 } /* Loop for addresses extracted from one RR */
2704 /* Carry on to the next RR. It would be nice to be able to be able to stop
2705 when every host on the list has an address, but we can't be sure there won't
2706 be an additional address for a multi-homed host further down the list, so
2707 we have to continue to the end. */
2709 DNS_NEXT_RR: continue;
2712 /* Set the default yield to failure */
2714 yield = HOST_FIND_FAILED;
2716 /* If we haven't found all the addresses in the additional section, we
2717 need to search for A or AAAA records explicitly. The names shouldn't point to
2718 CNAMES, but we use the general lookup function that handles them, just
2719 in case. If any lookup gives a soft error, change the default yield.
2721 For these DNS lookups, we must disable qualify_single and search_parents;
2722 otherwise invalid host names obtained from MX or SRV records can cause trouble
2723 if they happen to match something local. */
2725 dns_init(FALSE, FALSE);
2727 for (h = host; h != last->next; h = h->next)
2729 if (h->address != NULL || h->status == hstatus_unusable) continue;
2730 rc = set_address_from_dns(h, &last, ignore_target_hosts, allow_mx_to_ip, NULL);
2731 if (rc != HOST_FOUND)
2733 h->status = hstatus_unusable;
2734 if (rc == HOST_FIND_AGAIN)
2737 h->why = hwhy_deferred;
2740 h->why = (rc == HOST_IGNORED)? hwhy_ignored : hwhy_failed;
2744 /* Scan the list for any hosts that are marked unusable because they have
2745 been explicitly ignored, and remove them from the list, as if they did not
2746 exist. If we end up with just a single, ignored host, flatten its fields as if
2747 nothing was found. */
2749 if (ignore_target_hosts != NULL)
2751 host_item *prev = NULL;
2752 for (h = host; h != last->next; h = h->next)
2755 if (h->why != hwhy_ignored) /* Non ignored host, just continue */
2757 else if (prev == NULL) /* First host is ignored */
2759 if (h != last) /* First is not last */
2761 if (h->next == last) last = h; /* Overwrite it with next */
2762 *h = *(h->next); /* and reprocess it. */
2763 goto REDO; /* C should have redo, like Perl */
2766 else /* Ignored host is not first - */
2768 prev->next = h->next;
2769 if (h == last) last = prev;
2773 if (host->why == hwhy_ignored) host->address = NULL;
2776 /* There is still one complication in the case of IPv6. Although the code above
2777 arranges that IPv6 addresses take precedence over IPv4 addresses for multihomed
2778 hosts, it doesn't do this for addresses that apply to different hosts with the
2779 same MX precedence, because the sorting on MX precedence happens first. So we
2780 have to make another pass to check for this case. We ensure that, within a
2781 single MX preference value, IPv6 addresses come first. This can separate the
2782 addresses of a multihomed host, but that should not matter. */
2787 for (h = host; h != last; h = h->next)
2790 host_item *next = h->next;
2791 if (h->mx != next->mx || /* If next is different MX value */
2792 (h->sort_key % 1000) < 500 || /* OR this one is IPv6 */
2793 (next->sort_key % 1000) >= 500) /* OR next is IPv4 */
2794 continue; /* move on to next */
2796 temp.next = next->next;
2804 /* When running in the test harness, we want the hosts always to be in the same
2805 order so that the debugging output is the same and can be compared. Having a
2806 fixed set of "random" numbers doesn't actually achieve this, because the RRs
2807 come back from the resolver in a random order, so the non-random random numbers
2808 get used in a different order. We therefore have to sort the hosts that have
2809 the same MX values. We chose do to this by their name and then by IP address.
2810 The fact that the sort is slow matters not - this is testing only! */
2812 if (running_in_test_harness)
2818 for (h = host; h != last; h = h->next)
2820 int c = Ustrcmp(h->name, h->next->name);
2821 if (c == 0) c = Ustrcmp(h->address, h->next->address);
2822 if (h->mx == h->next->mx && c > 0)
2824 host_item *next = h->next;
2825 host_item temp = *h;
2826 temp.next = next->next;
2837 /* Remove any duplicate IP addresses and then scan the list of hosts for any
2838 whose IP addresses are on the local host. If any are found, all hosts with the
2839 same or higher MX values are removed. However, if the local host has the lowest
2840 numbered MX, then HOST_FOUND_LOCAL is returned. Otherwise, if at least one host
2841 with an IP address is on the list, HOST_FOUND is returned. Otherwise,
2842 HOST_FIND_FAILED is returned, but in this case do not update the yield, as it
2843 might have been set to HOST_FIND_AGAIN just above here. If not, it will already
2844 be HOST_FIND_FAILED. */
2846 host_remove_duplicates(host, &last);
2847 rc = host_scan_for_local_hosts(host, &last, removed);
2848 if (rc != HOST_FIND_FAILED) yield = rc;
2850 DEBUG(D_host_lookup)
2852 if (fully_qualified_name != NULL)
2853 debug_printf("fully qualified name = %s\n", *fully_qualified_name);
2854 debug_printf("host_find_bydns yield = %s (%d); returned hosts:\n",
2855 (yield == HOST_FOUND)? "HOST_FOUND" :
2856 (yield == HOST_FOUND_LOCAL)? "HOST_FOUND_LOCAL" :
2857 (yield == HOST_FIND_AGAIN)? "HOST_FIND_AGAIN" :
2858 (yield == HOST_FIND_FAILED)? "HOST_FIND_FAILED" : "?",
2860 for (h = host; h != last->next; h = h->next)
2862 debug_printf(" %s %s MX=%d ", h->name,
2863 (h->address == NULL)? US"<null>" : h->address, h->mx);
2864 if (h->port != PORT_NONE) debug_printf("port=%d ", h->port);
2865 if (h->status >= hstatus_unusable) debug_printf("*");
2876 /*************************************************
2877 **************************************************
2878 * Stand-alone test program *
2879 **************************************************
2880 *************************************************/
2884 BOOL alldigits(uschar *buffer)
2886 if (!isdigit(*buffer)) return FALSE;
2887 if (*buffer == '0' && buffer[1] == 'x')
2890 while (isxdigit(*(++buffer)));
2892 else while (isdigit(*(++buffer)));
2893 return (*buffer == 0);
2896 int main(int argc, char **cargv)
2899 int whichrrs = HOST_FIND_BY_MX | HOST_FIND_BY_A;
2900 BOOL byname = FALSE;
2901 BOOL qualify_single = TRUE;
2902 BOOL search_parents = FALSE;
2903 uschar **argv = USS cargv;
2906 primary_hostname = US"";
2907 store_pool = POOL_MAIN;
2908 debug_selector = D_host_lookup|D_interface;
2909 debug_file = stdout;
2910 debug_fd = fileno(debug_file);
2912 printf("Exim stand-alone host functions test\n");
2914 host_find_interfaces();
2915 debug_selector = D_host_lookup | D_dns;
2917 if (argc > 1) primary_hostname = argv[1];
2919 /* So that debug level changes can be done first */
2921 dns_init(qualify_single, search_parents);
2923 printf("Testing host lookup\n");
2925 while (Ufgets(buffer, 256, stdin) != NULL)
2928 int len = Ustrlen(buffer);
2929 uschar *fully_qualified_name;
2931 while (len > 0 && isspace(buffer[len-1])) len--;
2934 if (Ustrcmp(buffer, "q") == 0) break;
2936 if (Ustrcmp(buffer, "byname") == 0) byname = TRUE;
2937 else if (Ustrcmp(buffer, "no_byname") == 0) byname = FALSE;
2938 else if (Ustrcmp(buffer, "a_only") == 0) whichrrs = HOST_FIND_BY_A;
2939 else if (Ustrcmp(buffer, "mx_only") == 0) whichrrs = HOST_FIND_BY_MX;
2940 else if (Ustrcmp(buffer, "srv_only") == 0) whichrrs = HOST_FIND_BY_SRV;
2941 else if (Ustrcmp(buffer, "srv+a") == 0)
2942 whichrrs = HOST_FIND_BY_SRV | HOST_FIND_BY_A;
2943 else if (Ustrcmp(buffer, "srv+mx") == 0)
2944 whichrrs = HOST_FIND_BY_SRV | HOST_FIND_BY_MX;
2945 else if (Ustrcmp(buffer, "srv+mx+a") == 0)
2946 whichrrs = HOST_FIND_BY_SRV | HOST_FIND_BY_MX | HOST_FIND_BY_A;
2947 else if (Ustrcmp(buffer, "qualify_single") == 0) qualify_single = TRUE;
2948 else if (Ustrcmp(buffer, "no_qualify_single") == 0) qualify_single = FALSE;
2949 else if (Ustrcmp(buffer, "search_parents") == 0) search_parents = TRUE;
2950 else if (Ustrcmp(buffer, "no_search_parents") == 0) search_parents = FALSE;
2951 else if (Ustrncmp(buffer, "retrans", 7) == 0)
2953 sscanf(CS(buffer+8), "%d", &dns_retrans);
2954 _res.retrans = dns_retrans;
2956 else if (Ustrncmp(buffer, "retry", 5) == 0)
2958 sscanf(CS(buffer+6), "%d", &dns_retry);
2959 _res.retry = dns_retry;
2961 else if (alldigits(buffer))
2963 debug_selector = Ustrtol(buffer, NULL, 0);
2964 _res.options &= ~RES_DEBUG;
2965 DEBUG(D_resolver) _res.options |= RES_DEBUG;
2969 int flags = whichrrs;
2975 h.status = hstatus_unknown;
2976 h.why = hwhy_unknown;
2979 if (qualify_single) flags |= HOST_FIND_QUALIFY_SINGLE;
2980 if (search_parents) flags |= HOST_FIND_SEARCH_PARENTS;
2983 host_find_byname(&h, NULL, &fully_qualified_name, TRUE)
2985 host_find_bydns(&h, NULL, flags, US"smtp", NULL, NULL,
2986 &fully_qualified_name, NULL);
2988 if (rc == HOST_FIND_FAILED) printf("Failed\n");
2989 else if (rc == HOST_FIND_AGAIN) printf("Again\n");
2990 else if (rc == HOST_FOUND_LOCAL) printf("Local\n");
2996 printf("Testing host_aton\n");
2998 while (Ufgets(buffer, 256, stdin) != NULL)
3002 int len = Ustrlen(buffer);
3004 while (len > 0 && isspace(buffer[len-1])) len--;
3007 if (Ustrcmp(buffer, "q") == 0) break;
3009 len = host_aton(buffer, x);
3010 printf("length = %d ", len);
3011 for (i = 0; i < len; i++)
3013 printf("%04x ", (x[i] >> 16) & 0xffff);
3014 printf("%04x ", x[i] & 0xffff);
3021 printf("Testing host_name_lookup\n");
3023 while (Ufgets(buffer, 256, stdin) != NULL)
3025 int len = Ustrlen(buffer);
3026 while (len > 0 && isspace(buffer[len-1])) len--;
3028 if (Ustrcmp(buffer, "q") == 0) break;
3029 sender_host_address = buffer;
3030 sender_host_name = NULL;
3031 sender_host_aliases = NULL;
3032 host_lookup_msg = US"";
3033 host_lookup_failed = FALSE;
3034 if (host_name_lookup() == FAIL) /* Debug causes printing */
3035 printf("Lookup failed:%s\n", host_lookup_msg);
3043 #endif /* STAND_ALONE */