1 /* $Cambridge: exim/src/src/host.c,v 1.4 2004/12/29 10:16:53 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. The input address
758 is supposed to be checked for syntax. There was a case where this was
759 overlooked; to guard against that happening again, check here and crash if
760 there is a violation. */
764 int len = Ustrcspn(p, ":");
765 if (len == 0) nulloffset = ci;
766 if (ci > 7) log_write(0, LOG_MAIN|LOG_PANIC_DIE,
767 "Internal error: invalid IPv6 address \"%s\" passed to host_aton()",
774 /* If the final component contains a dot, it is a trailing v4 address.
775 As the syntax is known to be checked, just set up for a trailing
776 v4 address and restrict the v6 part to 6 components. */
778 if (Ustrchr(component[ci-1], '.') != NULL)
780 address = component[--ci];
786 /* If there are fewer than 6 or 8 components, we have to insert some
787 more empty ones in the middle. */
791 int insert_count = v6count - ci;
792 for (i = v6count-1; i > nulloffset + insert_count; i--)
793 component[i] = component[i - insert_count];
794 while (i > nulloffset) component[i--] = US"";
797 /* Now turn the components into binary in pairs and bung them
798 into the vector of ints. */
800 for (i = 0; i < v6count; i += 2)
801 bin[i/2] = (Ustrtol(component[i], NULL, 16) << 16) +
802 Ustrtol(component[i+1], NULL, 16);
804 /* If there was no terminating v4 component, we are done. */
806 if (!ipv4_ends) return 4;
809 /* Handle IPv4 address */
811 sscanf(CS address, "%d.%d.%d.%d", x, x+1, x+2, x+3);
812 bin[v4offset] = (x[0] << 24) + (x[1] << 16) + (x[2] << 8) + x[3];
817 /*************************************************
818 * Apply mask to an IP address *
819 *************************************************/
821 /* Mask an address held in 1 or 4 ints, with the ms bit in the ms bit of the
825 count the number of ints
826 binary points to the ints to be masked
827 mask the count of ms bits to leave, or -1 if no masking
833 host_mask(int count, int *binary, int mask)
836 if (mask < 0) mask = 99999;
837 for (i = 0; i < count; i++)
840 if (mask == 0) wordmask = 0;
843 wordmask = (-1) << (32 - mask);
851 binary[i] &= wordmask;
858 /*************************************************
859 * Convert masked IP address in ints to text *
860 *************************************************/
862 /* We can't use host_ntoa() because it assumes the binary values are in network
863 byte order, and these are the result of host_aton(), which puts them in ints in
864 host byte order. Also, we really want IPv6 addresses to be in a canonical
865 format, so we output them with no abbreviation. In a number of cases we can't
866 use the normal colon separator in them because it terminates keys in lsearch
867 files, so we want to use dot instead. There's an argument that specifies what
868 to use for IPv6 addresses.
871 count 1 or 4 (number of ints)
872 binary points to the ints
873 mask mask value; if < 0 don't add to result
874 buffer big enough to hold the result
875 sep component separator character for IPv6 addresses
877 Returns: the number of characters placed in buffer, not counting
882 host_nmtoa(int count, int *binary, int mask, uschar *buffer, int sep)
890 for (i = 24; i >= 0; i -= 8)
892 sprintf(CS tt, "%d.", (j >> i) & 255);
898 for (i = 0; i < 4; i++)
901 sprintf(CS tt, "%04x%c%04x%c", (j >> 16) & 0xffff, sep, j & 0xffff, sep);
906 tt--; /* lose final separator */
912 sprintf(CS tt, "/%d", mask);
921 /*************************************************
922 * Check port for tls_on_connect *
923 *************************************************/
925 /* This function checks whether a given incoming port is configured for tls-
926 on-connect. It is called from the daemon and from inetd handling. If the global
927 option tls_on_connect is already set, all ports operate this way. Otherwise, we
928 check the tls_on_connect_ports option for a list of ports.
930 Argument: a port number
931 Returns: TRUE or FALSE
935 host_is_tls_on_connect_port(int port)
939 uschar *list = tls_on_connect_ports;
942 if (tls_on_connect) return TRUE;
944 while ((s = string_nextinlist(&list, &sep, buffer, sizeof(buffer))) != NULL)
947 int lport = Ustrtol(s, &end, 10);
948 if (*end != 0) log_write(0, LOG_MAIN|LOG_PANIC_DIE, "tls_on_connect_ports "
949 "contains \"%s\", which is not a port number: exim abandoned", s);
950 if (lport == port) return TRUE;
958 /*************************************************
959 * Check whether host is in a network *
960 *************************************************/
962 /* This function checks whether a given IP address matches a pattern that
963 represents either a single host, or a network (using CIDR notation). The caller
964 of this function must check the syntax of the arguments before calling it.
967 host string representation of the ip-address to check
968 net string representation of the network, with optional CIDR mask
969 maskoffset offset to the / that introduces the mask in the key
970 zero if there is no mask
973 TRUE the host is inside the network
974 FALSE the host is NOT inside the network
978 host_is_in_net(uschar *host, uschar *net, int maskoffset)
984 int size = host_aton(net, address);
987 /* No mask => all bits to be checked */
989 if (maskoffset == 0) mlen = 99999; /* Big number */
990 else mlen = Uatoi(net + maskoffset + 1);
992 /* Convert the incoming address to binary. */
994 insize = host_aton(host, incoming);
996 /* Convert IPv4 addresses given in IPv6 compatible mode, which represent
997 connections from IPv4 hosts to IPv6 hosts, that is, addresses of the form
998 ::ffff:<v4address>, to IPv4 format. */
1000 if (insize == 4 && incoming[0] == 0 && incoming[1] == 0 &&
1001 incoming[2] == 0xffff)
1004 incoming[0] = incoming[3];
1007 /* No match if the sizes don't agree. */
1009 if (insize != size) return FALSE;
1011 /* Else do the masked comparison. */
1013 for (i = 0; i < size; i++)
1016 if (mlen == 0) mask = 0;
1019 mask = (-1) << (32 - mlen);
1027 if ((incoming[i] & mask) != (address[i] & mask)) return FALSE;
1035 /*************************************************
1036 * Scan host list for local hosts *
1037 *************************************************/
1039 /* Scan through a chain of addresses and check whether any of them is the
1040 address of an interface on the local machine. If so, remove that address and
1041 any previous ones with the same MX value, and all subsequent ones (which will
1042 have greater or equal MX values) from the chain. Note: marking them as unusable
1043 is NOT the right thing to do because it causes the hosts not to be used for
1044 other domains, for which they may well be correct.
1046 The hosts may be part of a longer chain; we only process those between the
1047 initial pointer and the "last" pointer.
1049 There is also a list of "pseudo-local" host names which are checked against the
1050 host names. Any match causes that host item to be treated the same as one which
1051 matches a local IP address.
1053 If the very first host is a local host, then all MX records had a precedence
1054 greater than or equal to that of the local host. Either there's a problem in
1055 the DNS, or an apparently remote name turned out to be an abbreviation for the
1056 local host. Give a specific return code, and let the caller decide what to do.
1057 Otherwise, give a success code if at least one host address has been found.
1060 host pointer to the first host in the chain
1061 lastptr pointer to pointer to the last host in the chain (may be updated)
1062 removed if not NULL, set TRUE if some local addresses were removed
1066 HOST_FOUND if there is at least one host with an IP address on the chain
1067 and an MX value less than any MX value associated with the
1069 HOST_FOUND_LOCAL if a local host is among the lowest-numbered MX hosts; when
1070 the host addresses were obtained from A records or
1071 gethostbyname(), the MX values are set to -1.
1072 HOST_FIND_FAILED if no valid hosts with set IP addresses were found
1076 host_scan_for_local_hosts(host_item *host, host_item **lastptr, BOOL *removed)
1078 int yield = HOST_FIND_FAILED;
1079 host_item *last = *lastptr;
1080 host_item *prev = NULL;
1083 if (removed != NULL) *removed = FALSE;
1085 if (local_interface_data == NULL) local_interface_data = host_find_interfaces();
1087 for (h = host; h != last->next; h = h->next)
1090 if (hosts_treat_as_local != NULL)
1093 uschar *save = deliver_domain;
1094 deliver_domain = h->name; /* set $domain */
1095 rc = match_isinlist(string_copylc(h->name), &hosts_treat_as_local, 0,
1096 &domainlist_anchor, NULL, MCL_DOMAIN, TRUE, NULL);
1097 deliver_domain = save;
1098 if (rc == OK) goto FOUND_LOCAL;
1102 /* It seems that on many operating systems, 0.0.0.0 is treated as a synonym
1103 for 127.0.0.1 and refers to the local host. We therefore force it always to
1104 be treated as local. */
1106 if (h->address != NULL)
1108 ip_address_item *ip;
1109 if (Ustrcmp(h->address, "0.0.0.0") == 0) goto FOUND_LOCAL;
1110 for (ip = local_interface_data; ip != NULL; ip = ip->next)
1111 if (Ustrcmp(h->address, ip->address) == 0) goto FOUND_LOCAL;
1112 yield = HOST_FOUND; /* At least one remote address has been found */
1115 /* Update prev to point to the last host item before any that have
1116 the same MX value as the one we have just considered. */
1118 if (h->next == NULL || h->next->mx != h->mx) prev = h;
1121 return yield; /* No local hosts found: return HOST_FOUND or HOST_FIND_FAILED */
1123 /* A host whose IP address matches a local IP address, or whose name matches
1124 something in hosts_treat_as_local has been found. */
1130 HDEBUG(D_host_lookup) debug_printf((h->mx >= 0)?
1131 "local host has lowest MX\n" :
1132 "local host found for non-MX address\n");
1133 return HOST_FOUND_LOCAL;
1136 HDEBUG(D_host_lookup)
1138 debug_printf("local host in host list - removed hosts:\n");
1139 for (h = prev->next; h != last->next; h = h->next)
1140 debug_printf(" %s %s %d\n", h->name, h->address, h->mx);
1143 if (removed != NULL) *removed = TRUE;
1144 prev->next = last->next;
1152 /*************************************************
1153 * Remove duplicate IPs in host list *
1154 *************************************************/
1156 /* You would think that administrators could set up their DNS records so that
1157 one ended up with a list of unique IP addresses after looking up A or MX
1158 records, but apparently duplication is common. So we scan such lists and
1159 remove the later duplicates. Note that we may get lists in which some host
1160 addresses are not set.
1163 host pointer to the first host in the chain
1164 lastptr pointer to pointer to the last host in the chain (may be updated)
1170 host_remove_duplicates(host_item *host, host_item **lastptr)
1172 while (host != *lastptr)
1174 if (host->address != NULL)
1176 host_item *h = host;
1177 while (h != *lastptr)
1179 if (h->next->address != NULL &&
1180 Ustrcmp(h->next->address, host->address) == 0)
1182 DEBUG(D_host_lookup) debug_printf("duplicate IP address %s (MX=%d) "
1183 "removed\n", host->address, h->next->mx);
1184 if (h->next == *lastptr) *lastptr = h;
1185 h->next = h->next->next;
1190 /* If the last item was removed, host may have become == *lastptr */
1191 if (host != *lastptr) host = host->next;
1198 /*************************************************
1199 * Find sender host name by gethostbyaddr() *
1200 *************************************************/
1202 /* This used to be the only way it was done, but it turns out that not all
1203 systems give aliases for calls to gethostbyaddr() - or one of the modern
1204 equivalents like getipnodebyaddr(). Fortunately, multiple PTR records are rare,
1205 but they can still exist. This function is now used only when a DNS lookup of
1206 the IP address fails, in order to give access to /etc/hosts.
1209 Returns: OK, DEFER, FAIL
1213 host_name_lookup_byaddr(void)
1217 struct hostent *hosts;
1218 struct in_addr addr;
1220 /* Lookup on IPv6 system */
1223 if (Ustrchr(sender_host_address, ':') != NULL)
1225 struct in6_addr addr6;
1226 if (inet_pton(AF_INET6, CS sender_host_address, &addr6) != 1)
1227 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "unable to parse \"%s\" as an "
1228 "IPv6 address", sender_host_address);
1229 #if HAVE_GETIPNODEBYADDR
1230 hosts = getipnodebyaddr(CS &addr6, sizeof(addr6), AF_INET6, &h_errno);
1232 hosts = gethostbyaddr(CS &addr6, sizeof(addr6), AF_INET6);
1237 if (inet_pton(AF_INET, CS sender_host_address, &addr) != 1)
1238 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "unable to parse \"%s\" as an "
1239 "IPv4 address", sender_host_address);
1240 #if HAVE_GETIPNODEBYADDR
1241 hosts = getipnodebyaddr(CS &addr, sizeof(addr), AF_INET, &h_errno);
1243 hosts = gethostbyaddr(CS &addr, sizeof(addr), AF_INET);
1247 /* Do lookup on IPv4 system */
1250 addr.s_addr = (S_ADDR_TYPE)inet_addr(CS sender_host_address);
1251 hosts = gethostbyaddr(CS(&addr), sizeof(addr), AF_INET);
1254 /* Failed to look up the host. */
1258 HDEBUG(D_host_lookup) debug_printf("IP address lookup failed: h_errno=%d\n",
1260 return (h_errno == TRY_AGAIN || h_errno == NO_RECOVERY) ? DEFER : FAIL;
1263 /* It seems there are some records in the DNS that yield an empty name. We
1264 treat this as non-existent. In some operating systems, this is returned as an
1265 empty string; in others as a single dot. */
1267 if (hosts->h_name[0] == 0 || hosts->h_name[0] == '.')
1269 HDEBUG(D_host_lookup) debug_printf("IP address lookup yielded an empty name: "
1270 "treated as non-existent host name\n");
1274 /* Copy and lowercase the name, which is in static storage in many systems.
1275 Put it in permanent memory. */
1277 s = (uschar *)hosts->h_name;
1278 len = Ustrlen(s) + 1;
1279 t = sender_host_name = store_get_perm(len);
1280 while (*s != 0) *t++ = tolower(*s++);
1283 /* If the host has aliases, build a copy of the alias list */
1285 if (hosts->h_aliases != NULL)
1288 uschar **aliases, **ptr;
1289 for (aliases = USS hosts->h_aliases; *aliases != NULL; aliases++) count++;
1290 ptr = sender_host_aliases = store_get_perm(count * sizeof(uschar *));
1291 for (aliases = USS hosts->h_aliases; *aliases != NULL; aliases++)
1293 uschar *s = *aliases;
1294 int len = Ustrlen(s) + 1;
1295 uschar *t = *ptr++ = store_get_perm(len);
1296 while (*s != 0) *t++ = tolower(*s++);
1307 /*************************************************
1308 * Find host name for incoming call *
1309 *************************************************/
1311 /* Put the name in permanent store, pointed to by sender_host_name. We also set
1312 up a list of alias names, pointed to by sender_host_alias. The list is
1313 NULL-terminated. The incoming address is in sender_host_address, either in
1314 dotted-quad form for IPv4 or in colon-separated form for IPv6.
1316 This function does a thorough check that the names it finds point back to the
1317 incoming IP address. Any that do not are discarded. Note that this is relied on
1318 by the ACL reverse_host_lookup check.
1320 On some systems, get{host,ipnode}byaddr() appears to do this internally, but
1321 this it not universally true. Also, for release 4.30, this function was changed
1322 to do a direct DNS lookup first, by default[1], because it turns out that that
1323 is the only guaranteed way to find all the aliases on some systems. My
1324 experiments indicate that Solaris gethostbyaddr() gives the aliases for but
1327 [1] The actual order is controlled by the host_lookup_order option.
1330 Returns: OK on success, the answer being placed in the global variable
1331 sender_host_name, with any aliases in a list hung off
1333 FAIL if no host name can be found
1334 DEFER if a temporary error was encountered
1336 The variable host_lookup_msg is set to an empty string on sucess, or to a
1337 reason for the failure otherwise, in a form suitable for tagging onto an error
1338 message, and also host_lookup_failed is set TRUE if the lookup failed. Any
1339 dynamically constructed string for host_lookup_msg must be in permanent store,
1340 because it might be used for several incoming messages on the same SMTP
1344 host_name_lookup(void)
1348 uschar *hname, *save_hostname;
1352 uschar *list = host_lookup_order;
1357 HDEBUG(D_host_lookup)
1358 debug_printf("looking up host name for %s\n", sender_host_address);
1360 /* For testing the case when a lookup does not complete, we have a special
1361 reserved IP address. */
1363 if (running_in_test_harness &&
1364 Ustrcmp(sender_host_address, "99.99.99.99") == 0)
1366 HDEBUG(D_host_lookup)
1367 debug_printf("Test harness: host name lookup returns DEFER\n");
1371 /* Do lookups directly in the DNS or via gethostbyaddr() (or equivalent), in
1372 the order specified by the host_lookup_order option. */
1374 while ((ordername = string_nextinlist(&list, &sep, buffer, sizeof(buffer)))
1377 if (strcmpic(ordername, US"bydns") == 0)
1379 dns_init(FALSE, FALSE);
1380 dns_build_reverse(sender_host_address, buffer);
1381 rc = dns_lookup(&dnsa, buffer, T_PTR, NULL);
1383 /* The first record we come across is used for the name; others are
1384 considered to be aliases. We have to scan twice, in order to find out the
1385 number of aliases. However, if all the names are empty, we will behave as
1386 if failure. (PTR records that yield empty names have been encountered in
1389 if (rc == DNS_SUCCEED)
1391 uschar **aptr = NULL;
1394 int old_pool = store_pool;
1396 store_pool = POOL_PERM; /* Save names in permanent storage */
1398 for (rr = dns_next_rr(&dnsa, &dnss, RESET_ANSWERS);
1400 rr = dns_next_rr(&dnsa, &dnss, RESET_NEXT))
1402 if (rr->type == T_PTR) count++;
1405 /* Get store for the list of aliases. For compatibility with
1406 gethostbyaddr, we make an empty list if there are none. */
1408 aptr = sender_host_aliases = store_get(count * sizeof(uschar *));
1410 /* Re-scan and extract the names */
1412 for (rr = dns_next_rr(&dnsa, &dnss, RESET_ANSWERS);
1414 rr = dns_next_rr(&dnsa, &dnss, RESET_NEXT))
1417 if (rr->type != T_PTR) continue;
1418 s = store_get(ssize);
1420 /* If an overlong response was received, the data will have been
1421 truncated and dn_expand may fail. */
1423 if (dn_expand(dnsa.answer, dnsa.answer + dnsa.answerlen,
1424 (uschar *)(rr->data), (DN_EXPAND_ARG4_TYPE)(s), ssize) < 0)
1426 log_write(0, LOG_MAIN, "host name alias list truncated for %s",
1427 sender_host_address);
1431 store_reset(s + Ustrlen(s) + 1);
1434 HDEBUG(D_host_lookup) debug_printf("IP address lookup yielded an "
1435 "empty name: treated as non-existent host name\n");
1438 if (sender_host_name == NULL) sender_host_name = s;
1440 while (*s != 0) { *s = tolower(*s); s++; }
1443 *aptr = NULL; /* End of alias list */
1444 store_pool = old_pool; /* Reset store pool */
1446 /* If we've found a names, break out of the "order" loop */
1448 if (sender_host_name != NULL) break;
1451 /* If the DNS lookup deferred, we must also defer. */
1453 if (rc == DNS_AGAIN)
1455 HDEBUG(D_host_lookup)
1456 debug_printf("IP address PTR lookup gave temporary error\n");
1461 /* Do a lookup using gethostbyaddr() - or equivalent */
1463 else if (strcmpic(ordername, US"byaddr") == 0)
1465 HDEBUG(D_host_lookup)
1466 debug_printf("IP address lookup using gethostbyaddr()\n");
1468 rc = host_name_lookup_byaddr();
1469 if (rc == DEFER) return rc; /* Can't carry on */
1470 if (rc == OK) break; /* Found a name */
1472 } /* Loop for bydns/byaddr scanning */
1474 /* If we have failed to find a name, return FAIL and log when required.
1475 NB host_lookup_msg must be in permanent store. */
1477 if (sender_host_name == NULL)
1479 if (host_checking || !log_testing_mode)
1480 log_write(L_host_lookup_failed, LOG_MAIN, "no host name found for IP "
1481 "address %s", sender_host_address);
1482 host_lookup_msg = US" (failed to find host name from IP address)";
1484 host_lookup_failed = TRUE;
1488 /* We have a host name. If we are running in the test harness, we want the host
1489 name and its alias to appear always the same way round. There are only ever two
1490 names in these tests. If one of them contains "alias", make sure it is second;
1491 otherwise put them in alphabetical order. */
1493 if (running_in_test_harness && *sender_host_aliases != NULL &&
1495 Ustrstr(sender_host_name, "alias") != NULL ||
1497 Ustrstr(*sender_host_aliases, "alias") == NULL &&
1498 Ustrcmp(sender_host_name, *sender_host_aliases) > 0
1502 uschar *temp = sender_host_name;
1503 sender_host_name = *sender_host_aliases;
1504 *sender_host_aliases = temp;
1507 /* Debug output what was found, after test harness swapping, for consistency */
1509 HDEBUG(D_host_lookup)
1511 uschar **aliases = sender_host_aliases;
1512 debug_printf("IP address lookup yielded %s\n", sender_host_name);
1513 while (*aliases != NULL) debug_printf(" alias %s\n", *aliases++);
1516 /* We need to verify that a forward lookup on the name we found does indeed
1517 correspond to the address. This is for security: in principle a malefactor who
1518 happened to own a reverse zone could set it to point to any names at all.
1520 This code was present in versions of Exim before 3.20. At that point I took it
1521 out because I thought that gethostbyaddr() did the check anyway. It turns out
1522 that this isn't always the case, so it's coming back in at 4.01. This version
1523 is actually better, because it also checks aliases.
1525 The code was made more robust at release 4.21. Prior to that, it accepted all
1526 the names if any of them had the correct IP address. Now the code checks all
1527 the names, and accepts only those that have the correct IP address. */
1529 save_hostname = sender_host_name; /* Save for error messages */
1530 aliases = sender_host_aliases;
1531 for (hname = sender_host_name; hname != NULL; hname = *aliases++)
1541 /* When called with the 5th argument FALSE, host_find_byname() won't return
1542 HOST_FOUND_LOCAL. If the incoming address is an IPv4 address expressed in
1543 IPv6 format, we must compare the IPv4 part to any IPv4 addresses. */
1545 if ((rc = host_find_byname(&h, NULL, NULL, FALSE)) == HOST_FOUND)
1548 uschar *address_ipv4 = (Ustrncmp(sender_host_address, "::ffff:", 7) == 0)?
1549 sender_host_address + 7 : sender_host_address;
1550 HDEBUG(D_host_lookup) debug_printf("checking addresses for %s\n", hname);
1551 for (hh = &h; hh != NULL; hh = hh->next)
1553 if ((Ustrcmp(hh->address, (Ustrchr(hh->address, ':') == NULL)?
1554 address_ipv4 : sender_host_address)) == 0)
1556 HDEBUG(D_host_lookup) debug_printf(" %s OK\n", hh->address);
1562 HDEBUG(D_host_lookup) debug_printf(" %s\n", hh->address);
1565 if (!ok) HDEBUG(D_host_lookup)
1566 debug_printf("no IP address for %s matched %s\n", hname,
1567 sender_host_address);
1569 else if (rc == HOST_FIND_AGAIN)
1571 HDEBUG(D_host_lookup) debug_printf("temporary error for host name lookup\n");
1576 HDEBUG(D_host_lookup) debug_printf("no IP addresses found for %s\n", hname);
1579 /* If this name is no good, and it's the sender name, set it null pro tem;
1580 if it's an alias, just remove it from the list. */
1584 if (hname == sender_host_name) sender_host_name = NULL; else
1586 uschar **a; /* Don't amalgamate - some */
1587 a = --aliases; /* compilers grumble */
1588 while (*a != NULL) { *a = a[1]; a++; }
1593 /* If sender_host_name == NULL, it means we didn't like the name. Replace
1594 it with the first alias, if there is one. */
1596 if (sender_host_name == NULL && *sender_host_aliases != NULL)
1597 sender_host_name = *sender_host_aliases++;
1599 /* If we now have a main name, all is well. */
1601 if (sender_host_name != NULL) return OK;
1603 /* We have failed to find an address that matches. */
1605 HDEBUG(D_host_lookup)
1606 debug_printf("%s does not match any IP address for %s\n",
1607 sender_host_address, save_hostname);
1609 /* This message must be in permanent store */
1611 old_pool = store_pool;
1612 store_pool = POOL_PERM;
1613 host_lookup_msg = string_sprintf(" (%s does not match any IP address for %s)",
1614 sender_host_address, save_hostname);
1615 store_pool = old_pool;
1617 host_lookup_failed = TRUE;
1624 /*************************************************
1625 * Find IP address(es) for host by name *
1626 *************************************************/
1628 /* The input is a host_item structure with the name filled in and the address
1629 field set to NULL. We use gethostbyname(). Of course, gethostbyname() may use
1630 the DNS, but it doesn't do MX processing. If more than one address is given,
1631 chain on additional host items, with other relevant fields copied.
1633 The second argument provides a host list (usually an IP list) of hosts to
1634 ignore. This makes it possible to ignore IPv6 link-local addresses or loopback
1635 addresses in unreasonable places.
1637 The lookup may result in a change of name. For compatibility with the dns
1638 lookup, return this via fully_qualified_name as well as updating the host item.
1639 The lookup may also yield more than one IP address, in which case chain on
1640 subsequent host_item structures.
1643 host a host item with the name and MX filled in;
1644 the address is to be filled in;
1645 multiple IP addresses cause other host items to be
1647 ignore_target_hosts a list of hosts to ignore
1648 fully_qualified_name if not NULL, set to point to host name for
1649 compatibility with host_find_bydns
1650 local_host_check TRUE if a check for the local host is wanted
1652 Returns: HOST_FIND_FAILED Failed to find the host or domain
1653 HOST_FIND_AGAIN Try again later
1654 HOST_FOUND Host found - data filled in
1655 HOST_FOUND_LOCAL Host found and is the local host
1659 host_find_byname(host_item *host, uschar *ignore_target_hosts,
1660 uschar **fully_qualified_name, BOOL local_host_check)
1662 int i, yield, times;
1664 host_item *last = NULL;
1665 BOOL temp_error = FALSE;
1667 /* In an IPv6 world, we need to scan for both kinds of address, so go round the
1668 loop twice. Note that we have ensured that AF_INET6 is defined even in an IPv4
1669 world, which makes for slightly tidier code. However, if dns_ipv4_lookup
1670 matches the domain, we also just do IPv4 lookups here (except when testing
1677 if (dns_ipv4_lookup != NULL &&
1678 match_isinlist(host->name, &dns_ipv4_lookup, 0, NULL, NULL, MCL_DOMAIN,
1680 { af = AF_INET; times = 1; }
1682 #endif /* STAND_ALONE */
1684 { af = AF_INET6; times = 2; }
1686 /* No IPv6 support */
1688 #else /* HAVE_IPV6 */
1690 #endif /* HAVE_IPV6 */
1692 /* Initialize the flag that gets set for DNS syntax check errors, so that the
1693 interface to this function can be similar to host_find_bydns. */
1695 host_find_failed_syntax = FALSE;
1697 /* Loop to look up both kinds of address in an IPv6 world */
1699 for (i = 1; i <= times;
1701 af = AF_INET, /* If 2 passes, IPv4 on the second */
1707 struct hostent *hostdata;
1710 #if HAVE_GETIPNODEBYNAME
1711 hostdata = getipnodebyname(CS host->name, af, 0, &error_num);
1713 hostdata = gethostbyname2(CS host->name, af);
1714 error_num = h_errno;
1717 hostdata = gethostbyname(CS host->name);
1718 error_num = h_errno;
1721 if (hostdata == NULL)
1726 case HOST_NOT_FOUND: error = US"HOST_NOT_FOUND"; break;
1727 case TRY_AGAIN: error = US"TRY_AGAIN"; break;
1728 case NO_RECOVERY: error = US"NO_RECOVERY"; break;
1729 case NO_DATA: error = US"NO_DATA"; break;
1730 #if NO_DATA != NO_ADDRESS
1731 case NO_ADDRESS: error = US"NO_ADDRESS"; break;
1733 default: error = US"?"; break;
1736 DEBUG(D_host_lookup) debug_printf("%s returned %d (%s)\n",
1738 #if HAVE_GETIPNODEBYNAME
1739 (af == AF_INET6)? "getipnodebyname(af=inet6)" : "getipnodebyname(af=inet)",
1741 (af == AF_INET6)? "gethostbyname2(af=inet6)" : "gethostbyname2(af=inet)",
1748 if (error_num == TRY_AGAIN || error_num == NO_RECOVERY) temp_error = TRUE;
1751 if ((hostdata->h_addr_list)[0] == NULL) continue;
1753 /* Replace the name with the fully qualified one if necessary, and fill in
1754 the fully_qualified_name pointer. */
1756 if (hostdata->h_name[0] != 0 &&
1757 Ustrcmp(host->name, hostdata->h_name) != 0)
1758 host->name = string_copy_dnsdomain((uschar *)hostdata->h_name);
1759 if (fully_qualified_name != NULL) *fully_qualified_name = host->name;
1761 /* Get the list of addresses. IPv4 and IPv6 addresses can be distinguished
1762 by their different lengths. Scan the list, ignoring any that are to be
1763 ignored, and build a chain from the rest. */
1765 ipv4_addr = hostdata->h_length == sizeof(struct in_addr);
1767 for (addrlist = USS hostdata->h_addr_list; *addrlist != NULL; addrlist++)
1769 uschar *text_address =
1770 host_ntoa(ipv4_addr? AF_INET:AF_INET6, *addrlist, NULL, NULL);
1773 if (ignore_target_hosts != NULL &&
1774 verify_check_this_host(&ignore_target_hosts, NULL, host->name,
1775 text_address, NULL) == OK)
1777 DEBUG(D_host_lookup)
1778 debug_printf("ignored host %s [%s]\n", host->name, text_address);
1783 /* If this is the first address, last == NULL and we put the data in the
1788 host->address = text_address;
1789 host->port = PORT_NONE;
1790 host->status = hstatus_unknown;
1791 host->why = hwhy_unknown;
1795 /* Else add further host item blocks for any other addresses, keeping
1800 host_item *next = store_get(sizeof(host_item));
1801 next->name = host->name;
1802 next->mx = host->mx;
1803 next->address = text_address;
1804 next->port = PORT_NONE;
1805 next->status = hstatus_unknown;
1806 next->why = hwhy_unknown;
1808 next->next = last->next;
1815 /* If no hosts were found, the address field in the original host block will be
1816 NULL. If temp_error is set, at least one of the lookups gave a temporary error,
1817 so we pass that back. */
1819 if (host->address == NULL)
1823 (message_id[0] == 0 && smtp_in != NULL)?
1824 string_sprintf("no IP address found for host %s (during %s)", host->name,
1825 smtp_get_connection_info()) :
1827 string_sprintf("no IP address found for host %s", host->name);
1829 HDEBUG(D_host_lookup) debug_printf("%s\n", msg);
1830 if (temp_error) return HOST_FIND_AGAIN;
1831 if (host_checking || !log_testing_mode)
1832 log_write(L_host_lookup_failed, LOG_MAIN, "%s", msg);
1833 return HOST_FIND_FAILED;
1836 /* Remove any duplicate IP addresses, then check to see if this is the local
1837 host if required. */
1839 host_remove_duplicates(host, &last);
1840 yield = local_host_check?
1841 host_scan_for_local_hosts(host, &last, NULL) : HOST_FOUND;
1843 /* When running in the test harness, sort into the order of addresses so as to
1844 get repeatability. */
1846 if (running_in_test_harness) sort_addresses(host, last);
1848 HDEBUG(D_host_lookup)
1851 if (fully_qualified_name != NULL)
1852 debug_printf("fully qualified name = %s\n", *fully_qualified_name);
1853 debug_printf("%s looked up these IP addresses:\n",
1855 #if HAVE_GETIPNODEBYNAME
1864 for (h = host; h != last->next; h = h->next)
1865 debug_printf(" name=%s address=%s\n", h->name,
1866 (h->address == NULL)? US"<null>" : h->address);
1869 /* Return the found status. */
1876 /*************************************************
1877 * Fill in a host address from the DNS *
1878 *************************************************/
1880 /* Given a host item, with its name and mx fields set, and its address field
1881 set to NULL, fill in its IP address from the DNS. If it is multi-homed, create
1882 additional host items for the additional addresses, copying all the other
1883 fields, and randomizing the order.
1885 On IPv6 systems, A6 records are sought first (but only if support for A6 is
1886 configured - they may never become mainstream), then AAAA records are sought,
1887 and finally A records are sought as well.
1889 The host name may be changed if the DNS returns a different name - e.g. fully
1890 qualified or changed via CNAME. If fully_qualified_name is not NULL, dns_lookup
1891 ensures that it points to the fully qualified name. However, this is the fully
1892 qualified version of the original name; if a CNAME is involved, the actual
1893 canonical host name may be different again, and so we get it directly from the
1894 relevant RR. Note that we do NOT change the mx field of the host item in this
1895 function as it may be called to set the addresses of hosts taken from MX
1899 host points to the host item we're filling in
1900 lastptr points to pointer to last host item in a chain of
1901 host items (may be updated if host is last and gets
1902 extended because multihomed)
1903 ignore_target_hosts list of hosts to ignore
1904 allow_ip if TRUE, recognize an IP address and return it
1905 fully_qualified_name if not NULL, return fully qualified name here if
1906 the contents are different (i.e. it must be preset
1909 Returns: HOST_FIND_FAILED couldn't find A record
1910 HOST_FIND_AGAIN try again later
1911 HOST_FOUND found AAAA and/or A record(s)
1912 HOST_IGNORED found, but all IPs ignored
1916 set_address_from_dns(host_item *host, host_item **lastptr,
1917 uschar *ignore_target_hosts, BOOL allow_ip, uschar **fully_qualified_name)
1920 host_item *thishostlast = NULL; /* Indicates not yet filled in anything */
1921 BOOL v6_find_again = FALSE;
1924 /* If allow_ip is set, a name which is an IP address returns that value
1925 as its address. This is used for MX records when allow_mx_to_ip is set, for
1926 those sites that feel they have to flaunt the RFC rules. */
1928 if (allow_ip && string_is_ip_address(host->name, NULL) != 0)
1931 if (ignore_target_hosts != NULL &&
1932 verify_check_this_host(&ignore_target_hosts, NULL, host->name,
1933 host->name, NULL) == OK)
1934 return HOST_IGNORED;
1937 host->address = host->name;
1938 host->port = PORT_NONE;
1942 /* On an IPv6 system, go round the loop up to three times, looking for A6 and
1943 AAAA records the first two times. However, unless doing standalone testing, we
1944 force an IPv4 lookup if the domain matches dns_ipv4_lookup is set. Since A6
1945 records look like being abandoned, support them only if explicitly configured
1946 to do so. On an IPv4 system, go round the loop once only, looking only for A
1952 if (dns_ipv4_lookup != NULL &&
1953 match_isinlist(host->name, &dns_ipv4_lookup, 0, NULL, NULL, MCL_DOMAIN,
1955 i = 0; /* look up A records only */
1957 #endif /* STAND_ALONE */
1960 i = 2; /* look up A6 and AAAA and A records */
1962 i = 1; /* look up AAAA and A records */
1963 #endif /* SUPPORT_A6 */
1965 /* The IPv4 world */
1967 #else /* HAVE_IPV6 */
1968 i = 0; /* look up A records only */
1969 #endif /* HAVE_IPV6 */
1973 static int types[] = { T_A, T_AAAA, T_A6 };
1974 int type = types[i];
1975 int randoffset = (i == 0)? 500 : 0; /* Ensures v6 sorts before v4 */
1979 int rc = dns_lookup(&dnsa, host->name, type, fully_qualified_name);
1981 /* We want to return HOST_FIND_AGAIN if one of the A, A6, or AAAA lookups
1982 fails or times out, but not if another one succeeds. (In the early
1983 IPv6 days there are name servers that always fail on AAAA, but are happy
1984 to give out an A record. We want to proceed with that A record.) */
1986 if (rc != DNS_SUCCEED)
1988 if (i == 0) /* Just tried for an A record, i.e. end of loop */
1990 if (host->address != NULL) return HOST_FOUND; /* A6 or AAAA was found */
1991 if (rc == DNS_AGAIN || rc == DNS_FAIL || v6_find_again)
1992 return HOST_FIND_AGAIN;
1993 return HOST_FIND_FAILED; /* DNS_NOMATCH or DNS_NODATA */
1996 /* Tried for an A6 or AAAA record: remember if this was a temporary
1997 error, and look for the next record type. */
1999 if (rc != DNS_NOMATCH && rc != DNS_NODATA) v6_find_again = TRUE;
2003 /* Lookup succeeded: fill in the given host item with the first non-ignored
2004 address found; create additional items for any others. A single A6 record
2005 may generate more than one address. */
2007 for (rr = dns_next_rr(&dnsa, &dnss, RESET_ANSWERS);
2009 rr = dns_next_rr(&dnsa, &dnss, RESET_NEXT))
2011 if (rr->type == type)
2013 /* dns_address *da = dns_address_from_rr(&dnsa, rr); */
2016 da = dns_address_from_rr(&dnsa, rr);
2018 DEBUG(D_host_lookup)
2021 debug_printf("no addresses extracted from A6 RR for %s\n",
2025 /* This loop runs only once for A and AAAA records, but may run
2026 several times for an A6 record that generated multiple addresses. */
2028 for (; da != NULL; da = da->next)
2031 if (ignore_target_hosts != NULL &&
2032 verify_check_this_host(&ignore_target_hosts, NULL,
2033 host->name, da->address, NULL) == OK)
2035 DEBUG(D_host_lookup)
2036 debug_printf("ignored host %s [%s]\n", host->name, da->address);
2041 /* If this is the first address, stick it in the given host block,
2042 and change the name if the returned RR has a different name. */
2044 if (thishostlast == NULL)
2046 if (strcmpic(host->name, rr->name) != 0)
2047 host->name = string_copy_dnsdomain(rr->name);
2048 host->address = da->address;
2049 host->port = PORT_NONE;
2050 host->sort_key = host->mx * 1000 + random_number(500) + randoffset;
2051 host->status = hstatus_unknown;
2052 host->why = hwhy_unknown;
2053 thishostlast = host;
2056 /* Not the first address. Check for, and ignore, duplicates. Then
2057 insert in the chain at a random point. */
2064 /* End of our local chain is specified by "thishostlast". */
2066 for (next = host;; next = next->next)
2068 if (Ustrcmp(CS da->address, next->address) == 0) break;
2069 if (next == thishostlast) { next = NULL; break; }
2071 if (next != NULL) continue; /* With loop for next address */
2073 /* Not a duplicate */
2075 new_sort_key = host->mx * 1000 + random_number(500) + randoffset;
2076 next = store_get(sizeof(host_item));
2078 /* New address goes first: insert the new block after the first one
2079 (so as not to disturb the original pointer) but put the new address
2080 in the original block. */
2082 if (new_sort_key < host->sort_key)
2086 host->address = da->address;
2087 host->port = PORT_NONE;
2088 host->sort_key = new_sort_key;
2089 if (thishostlast == host) thishostlast = next; /* Local last */
2090 if (*lastptr == host) *lastptr = next; /* Global last */
2093 /* Otherwise scan down the addresses for this host to find the
2094 one to insert after. */
2098 host_item *h = host;
2099 while (h != thishostlast)
2101 if (new_sort_key < h->next->sort_key) break;
2106 next->address = da->address;
2107 next->port = PORT_NONE;
2108 next->sort_key = new_sort_key;
2109 if (h == thishostlast) thishostlast = next; /* Local last */
2110 if (h == *lastptr) *lastptr = next; /* Global last */
2118 /* Control gets here only if the third lookup (the A record) succeeded.
2119 However, the address may not be filled in if it was ignored. */
2121 return (host->address == NULL)? HOST_IGNORED : HOST_FOUND;
2127 /*************************************************
2128 * Find IP addresses and names for host via DNS *
2129 *************************************************/
2131 /* The input is a host_item structure with the name filled in and the address
2132 field set to NULL. This may be in a chain of other host items. The lookup may
2133 result in more than one IP address, in which case we must created new host
2134 blocks for the additional addresses, and insert them into the chain. The
2135 original name may not be fully qualified. Use the fully_qualified_name argument
2136 to return the official name, as returned by the resolver.
2139 host point to initial host item
2140 ignore_target_hosts a list of hosts to ignore
2141 whichrrs flags indicating which RRs to look for:
2142 HOST_FIND_BY_SRV => look for SRV
2143 HOST_FIND_BY_MX => look for MX
2144 HOST_FIND_BY_A => look for A or AAAA
2145 also flags indicating how the lookup is done
2146 HOST_FIND_QUALIFY_SINGLE ) passed to the
2147 HOST_FIND_SEARCH_PARENTS ) resolver
2148 srv_service when SRV used, the service name
2149 srv_fail_domains DNS errors for these domains => assume nonexist
2150 mx_fail_domains DNS errors for these domains => assume nonexist
2151 fully_qualified_name if not NULL, return fully-qualified name
2152 removed set TRUE if local host was removed from the list
2154 Returns: HOST_FIND_FAILED Failed to find the host or domain;
2155 if there was a syntax error,
2156 host_find_failed_syntax is set.
2157 HOST_FIND_AGAIN Could not resolve at this time
2158 HOST_FOUND Host found
2159 HOST_FOUND_LOCAL The lowest MX record points to this
2160 machine, if MX records were found, or
2161 an A record that was found contains
2162 an address of the local host
2166 host_find_bydns(host_item *host, uschar *ignore_target_hosts, int whichrrs,
2167 uschar *srv_service, uschar *srv_fail_domains, uschar *mx_fail_domains,
2168 uschar **fully_qualified_name, BOOL *removed)
2170 host_item *h, *last;
2178 /* Set the default fully qualified name to the incoming name, initialize the
2179 resolver if necessary, set up the relevant options, and initialize the flag
2180 that gets set for DNS syntax check errors. */
2182 if (fully_qualified_name != NULL) *fully_qualified_name = host->name;
2183 dns_init((whichrrs & HOST_FIND_QUALIFY_SINGLE) != 0,
2184 (whichrrs & HOST_FIND_SEARCH_PARENTS) != 0);
2185 host_find_failed_syntax = FALSE;
2187 /* First, if requested, look for SRV records. The service name is given; we
2188 assume TCP progocol. DNS domain names are constrained to a maximum of 256
2189 characters, so the code below should be safe. */
2191 if ((whichrrs & HOST_FIND_BY_SRV) != 0)
2194 uschar *temp_fully_qualified_name = buffer;
2197 (void)sprintf(CS buffer, "_%s._tcp.%n%.256s", srv_service, &prefix_length,
2201 /* Search for SRV records. If the fully qualified name is different to
2202 the input name, pass back the new original domain, without the prepended
2205 rc = dns_lookup(&dnsa, buffer, ind_type, &temp_fully_qualified_name);
2206 if (temp_fully_qualified_name != buffer && fully_qualified_name != NULL)
2207 *fully_qualified_name = temp_fully_qualified_name + prefix_length;
2209 /* On DNS failures, we give the "try again" error unless the domain is
2210 listed as one for which we continue. */
2212 if (rc == DNS_FAIL || rc == DNS_AGAIN)
2214 if (match_isinlist(host->name, &srv_fail_domains, 0, NULL, NULL, MCL_DOMAIN,
2216 return HOST_FIND_AGAIN;
2217 DEBUG(D_host_lookup) debug_printf("DNS_%s treated as DNS_NODATA "
2218 "(domain in srv_fail_domains)\n", (rc == DNS_FAIL)? "FAIL":"AGAIN");
2222 /* If we did not find any SRV records, search the DNS for MX records, if
2223 requested to do so. If the result is DNS_NOMATCH, it means there is no such
2224 domain, and there's no point in going on to look for address records with the
2225 same domain. The result will be DNS_NODATA if the domain exists but has no MX
2226 records. On DNS failures, we give the "try again" error unless the domain is
2227 listed as one for which we continue. */
2229 if (rc != DNS_SUCCEED && (whichrrs & HOST_FIND_BY_MX) != 0)
2232 rc = dns_lookup(&dnsa, host->name, ind_type, fully_qualified_name);
2233 if (rc == DNS_NOMATCH) return HOST_FIND_FAILED;
2234 if (rc == DNS_FAIL || rc == DNS_AGAIN)
2236 if (match_isinlist(host->name, &mx_fail_domains, 0, NULL, NULL, MCL_DOMAIN,
2238 return HOST_FIND_AGAIN;
2239 DEBUG(D_host_lookup) debug_printf("DNS_%s treated as DNS_NODATA "
2240 "(domain in mx_fail_domains)\n", (rc == DNS_FAIL)? "FAIL":"AGAIN");
2244 /* If we haven't found anything yet, and we are requested to do so, try for an
2245 A or AAAA record. If we find it (or them) check to see that it isn't the local
2248 if (rc != DNS_SUCCEED)
2250 if ((whichrrs & HOST_FIND_BY_A) == 0)
2252 DEBUG(D_host_lookup) debug_printf("Address records are not being sought\n");
2253 return HOST_FIND_FAILED;
2256 last = host; /* End of local chainlet */
2258 host->port = PORT_NONE;
2259 rc = set_address_from_dns(host, &last, ignore_target_hosts, FALSE,
2260 fully_qualified_name);
2262 /* If one or more address records have been found, check that none of them
2263 are local. Since we know the host items all have their IP addresses
2264 inserted, host_scan_for_local_hosts() can only return HOST_FOUND or
2265 HOST_FOUND_LOCAL. We do not need to scan for duplicate IP addresses here,
2266 because set_address_from_dns() removes them. */
2268 if (rc == HOST_FOUND)
2269 rc = host_scan_for_local_hosts(host, &last, removed);
2271 if (rc == HOST_IGNORED) rc = HOST_FIND_FAILED; /* No special action */
2273 /* When running in the test harness, sort into the order of addresses so as
2274 to get repeatability. */
2276 if (running_in_test_harness) sort_addresses(host, last);
2278 DEBUG(D_host_lookup)
2281 if (host->address != NULL)
2283 if (fully_qualified_name != NULL)
2284 debug_printf("fully qualified name = %s\n", *fully_qualified_name);
2285 for (h = host; h != last->next; h = h->next)
2286 debug_printf("%s %s mx=%d sort=%d %s\n", h->name,
2287 (h->address == NULL)? US"<null>" : h->address, h->mx, h->sort_key,
2288 (h->status >= hstatus_unusable)? US"*" : US"");
2295 /* We have found one or more MX or SRV records. Sort them according to
2296 precedence. Put the data for the first one into the existing host block, and
2297 insert new host_item blocks into the chain for the remainder. For equal
2298 precedences one is supposed to randomize the order. To make this happen, the
2299 sorting is actually done on the MX value * 1000 + a random number. This is put
2300 into a host field called sort_key.
2302 In the case of hosts with both IPv6 and IPv4 addresses, we want to choose the
2303 IPv6 address in preference. At this stage, we don't know what kind of address
2304 the host has. We choose a random number < 500; if later we find an A record
2305 first, we add 500 to the random number. Then for any other address records, we
2306 use random numbers in the range 0-499 for AAAA records and 500-999 for A
2309 At this point we remove any duplicates that point to the same host, retaining
2310 only the one with the lowest precedence. We cannot yet check for precedence
2311 greater than that of the local host, because that test cannot be properly done
2312 until the addresses have been found - an MX record may point to a name for this
2313 host which is not the primary hostname. */
2315 last = NULL; /* Indicates that not even the first item is filled yet */
2317 for (rr = dns_next_rr(&dnsa, &dnss, RESET_ANSWERS);
2319 rr = dns_next_rr(&dnsa, &dnss, RESET_NEXT))
2322 int weight = 0; /* For SRV records */
2323 int port = PORT_NONE; /* For SRV records */
2324 uschar *s; /* MUST be unsigned for GETSHORT */
2327 if (rr->type != ind_type) continue;
2329 GETSHORT(precedence, s); /* Pointer s is advanced */
2331 /* For MX records, we use a random "weight" which causes multiple records of
2332 the same precedence to sort randomly. */
2334 if (ind_type == T_MX)
2336 weight = random_number(500);
2339 /* SRV records are specified with a port and a weight. The weight is used
2340 in a special algorithm. However, to start with, we just use it to order the
2341 records of equal priority (precedence). */
2345 GETSHORT(weight, s);
2349 /* Get the name of the host pointed to. */
2351 (void)dn_expand(dnsa.answer, dnsa.answer + dnsa.answerlen, s,
2352 (DN_EXPAND_ARG4_TYPE)data, sizeof(data));
2354 /* Check that we haven't already got this host on the chain; if we have,
2355 keep only the lower precedence. This situation shouldn't occur, but you
2356 never know what junk might get into the DNS (and this case has been seen on
2357 more than one occasion). */
2359 if (last != NULL) /* This is not the first record */
2361 host_item *prev = NULL;
2363 for (h = host; h != last->next; prev = h, h = h->next)
2365 if (strcmpic(h->name, data) == 0)
2367 DEBUG(D_host_lookup)
2368 debug_printf("discarded duplicate host %s (MX=%d)\n", data,
2369 (precedence > h->mx)? precedence : h->mx);
2370 if (precedence >= h->mx) goto NEXT_MX_RR; /* Skip greater precedence */
2371 if (h == host) /* Override first item */
2374 host->sort_key = precedence * 1000 + weight;
2378 /* Unwanted host item is not the first in the chain, so we can get
2379 get rid of it by cutting it out. */
2381 prev->next = h->next;
2382 if (h == last) last = prev;
2388 /* If this is the first MX or SRV record, put the data into the existing host
2389 block. Otherwise, add a new block in the correct place; if it has to be
2390 before the first block, copy the first block's data to a new second block. */
2394 host->name = string_copy_dnsdomain(data);
2395 host->address = NULL;
2397 host->mx = precedence;
2398 host->sort_key = precedence * 1000 + weight;
2399 host->status = hstatus_unknown;
2400 host->why = hwhy_unknown;
2404 /* Make a new host item and seek the correct insertion place */
2408 int sort_key = precedence * 1000 + weight;
2409 host_item *next = store_get(sizeof(host_item));
2410 next->name = string_copy_dnsdomain(data);
2411 next->address = NULL;
2413 next->mx = precedence;
2414 next->sort_key = sort_key;
2415 next->status = hstatus_unknown;
2416 next->why = hwhy_unknown;
2419 /* Handle the case when we have to insert before the first item. */
2421 if (sort_key < host->sort_key)
2428 if (last == host) last = next;
2431 /* Else scan down the items we have inserted as part of this exercise;
2432 don't go further. */
2436 for (h = host; h != last; h = h->next)
2438 if (sort_key < h->next->sort_key)
2440 next->next = h->next;
2446 /* Join on after the last host item that's part of this
2447 processing if we haven't stopped sooner. */
2451 next->next = last->next;
2458 NEXT_MX_RR: continue;
2461 /* If the list of hosts was obtained from SRV records, there are two things to
2462 do. First, if there is only one host, and it's name is ".", it means there is
2463 no SMTP service at this domain. Otherwise, we have to sort the hosts of equal
2464 priority according to their weights, using an algorithm that is defined in RFC
2465 2782. The hosts are currently sorted by priority and weight. For each priority
2466 group we have to pick off one host and put it first, and then repeat for any
2467 remaining in the same priority group. */
2469 if (ind_type == T_SRV)
2473 if (host == last && host->name[0] == 0)
2475 DEBUG(D_host_lookup) debug_printf("the single SRV record is \".\"\n");
2476 return HOST_FIND_FAILED;
2479 DEBUG(D_host_lookup)
2481 debug_printf("original ordering of hosts from SRV records:\n");
2482 for (h = host; h != last->next; h = h->next)
2483 debug_printf(" %s P=%d W=%d\n", h->name, h->mx, h->sort_key % 1000);
2486 for (pptr = &host, h = host; h != last; pptr = &(h->next), h = h->next)
2491 /* Find the last following host that has the same precedence. At the same
2492 time, compute the sum of the weights and the running totals. These can be
2493 stored in the sort_key field. */
2495 for (hh = h; hh != last; hh = hh->next)
2497 int weight = hh->sort_key % 1000; /* was precedence * 1000 + weight */
2500 if (hh->mx != hh->next->mx) break;
2503 /* If there's more than one host at this precedence (priority), we need to
2504 pick one to go first. */
2510 int randomizer = random_number(sum + 1);
2512 for (ppptr = pptr, hhh = h;
2514 ppptr = &(hhh->next), hhh = hhh->next)
2516 if (hhh->sort_key >= randomizer) break;
2519 /* hhh now points to the host that should go first; ppptr points to the
2520 place that points to it. Unfortunately, if the start of the minilist is
2521 the start of the entire list, we can't just swap the items over, because
2522 we must not change the value of host, since it is passed in from outside.
2523 One day, this could perhaps be changed.
2525 The special case is fudged by putting the new item *second* in the chain,
2526 and then transferring the data between the first and second items. We
2527 can't just swap the first and the chosen item, because that would mean
2528 that an item with zero weight might no longer be first. */
2532 *ppptr = hhh->next; /* Cuts it out of the chain */
2536 host_item temp = *h;
2539 hhh->next = temp.next;
2545 hhh->next = h; /* The rest of the chain follows it */
2546 *pptr = hhh; /* It takes the place of h */
2547 h = hhh; /* It's now the start of this minilist */
2552 /* A host has been chosen to be first at this priority and h now points
2553 to this host. There may be others at the same priority, or others at a
2554 different priority. Before we leave this host, we need to put back a sort
2555 key of the traditional MX kind, in case this host is multihomed, because
2556 the sort key is used for ordering the multiple IP addresses. We do not need
2557 to ensure that these new sort keys actually reflect the order of the hosts,
2560 h->sort_key = h->mx * 1000 + random_number(500);
2561 } /* Move on to the next host */
2564 /* Now we have to ensure addresses exist for all the hosts. We have ensured
2565 above that the names in the host items are all unique. The addresses may have
2566 been returned in the additional data section of the DNS query. Because it is
2567 more expensive to scan the returned DNS records (because you have to expand the
2568 names) we do a single scan over them, and multiple scans of the chain of host
2569 items (which is typically only 3 or 4 long anyway.) Add extra host items for
2570 multi-homed hosts. */
2572 for (rr = dns_next_rr(&dnsa, &dnss, RESET_ADDITIONAL);
2574 rr = dns_next_rr(&dnsa, &dnss, RESET_NEXT))
2577 int status = hstatus_unknown;
2578 int why = hwhy_unknown;
2583 && rr->type != T_AAAA
2590 /* Find the first host that matches this record's name. If there isn't
2591 one, move on to the next RR. */
2593 for (h = host; h != last->next; h = h->next)
2594 { if (strcmpic(h->name, rr->name) == 0) break; }
2595 if (h == last->next) continue;
2597 /* For IPv4 addresses, add 500 to the random part of the sort key, to ensure
2598 they sort after IPv6 addresses. */
2600 randoffset = (rr->type == T_A)? 500 : 0;
2602 /* Get the list of textual addresses for this RR. There may be more than one
2603 if it is an A6 RR. Then loop to handle multiple addresses from an A6 record.
2604 If there are none, nothing will get done - the record is ignored. */
2606 for (da = dns_address_from_rr(&dnsa, rr); da != NULL; da = da->next)
2608 /* Set status for an ignorable host. */
2611 if (ignore_target_hosts != NULL &&
2612 verify_check_this_host(&ignore_target_hosts, NULL, h->name,
2613 da->address, NULL) == OK)
2615 DEBUG(D_host_lookup)
2616 debug_printf("ignored host %s [%s]\n", h->name, da->address);
2617 status = hstatus_unusable;
2622 /* If the address is already set for this host, it may be that
2623 we just have a duplicate DNS record. Alternatively, this may be
2624 a multi-homed host. Search all items with the same host name
2625 (they will all be together) and if this address is found, skip
2628 if (h->address != NULL)
2631 host_item *thishostlast;
2636 if (hh->address != NULL && Ustrcmp(CS da->address, hh->address) == 0)
2637 goto DNS_NEXT_RR; /* Need goto to escape from inner loop */
2641 while (hh != last->next && strcmpic(hh->name, rr->name) == 0);
2643 /* We have a multi-homed host, since we have a new address for
2644 an existing name. Create a copy of the current item, and give it
2645 the new address. RRs can be in arbitrary order, but one is supposed
2646 to randomize the addresses of multi-homed hosts, so compute a new
2647 sorting key and do that. [Latest SMTP RFC says not to randomize multi-
2648 homed hosts, but to rely on the resolver. I'm not happy about that -
2649 caching in the resolver will not rotate as often as the name server
2652 new_sort_key = h->mx * 1000 + random_number(500) + randoffset;
2653 hh = store_get(sizeof(host_item));
2655 /* New address goes first: insert the new block after the first one
2656 (so as not to disturb the original pointer) but put the new address
2657 in the original block. */
2659 if (new_sort_key < h->sort_key)
2661 *hh = *h; /* Note: copies the port */
2663 h->address = da->address;
2664 h->sort_key = new_sort_key;
2669 /* Otherwise scan down the addresses for this host to find the
2670 one to insert after. */
2674 while (h != thishostlast)
2676 if (new_sort_key < h->next->sort_key) break;
2679 *hh = *h; /* Note: copies the port */
2681 hh->address = da->address;
2682 hh->sort_key = new_sort_key;
2683 hh->status = status;
2687 if (h == last) last = hh; /* Inserted after last */
2690 /* The existing item doesn't have its address set yet, so just set it.
2691 Ensure that an IPv4 address gets its sort key incremented in case an IPv6
2692 address is found later. */
2696 h->address = da->address; /* Port should be set already */
2699 h->sort_key += randoffset;
2701 } /* Loop for addresses extracted from one RR */
2703 /* Carry on to the next RR. It would be nice to be able to be able to stop
2704 when every host on the list has an address, but we can't be sure there won't
2705 be an additional address for a multi-homed host further down the list, so
2706 we have to continue to the end. */
2708 DNS_NEXT_RR: continue;
2711 /* Set the default yield to failure */
2713 yield = HOST_FIND_FAILED;
2715 /* If we haven't found all the addresses in the additional section, we
2716 need to search for A or AAAA records explicitly. The names shouldn't point to
2717 CNAMES, but we use the general lookup function that handles them, just
2718 in case. If any lookup gives a soft error, change the default yield.
2720 For these DNS lookups, we must disable qualify_single and search_parents;
2721 otherwise invalid host names obtained from MX or SRV records can cause trouble
2722 if they happen to match something local. */
2724 dns_init(FALSE, FALSE);
2726 for (h = host; h != last->next; h = h->next)
2728 if (h->address != NULL || h->status == hstatus_unusable) continue;
2729 rc = set_address_from_dns(h, &last, ignore_target_hosts, allow_mx_to_ip, NULL);
2730 if (rc != HOST_FOUND)
2732 h->status = hstatus_unusable;
2733 if (rc == HOST_FIND_AGAIN)
2736 h->why = hwhy_deferred;
2739 h->why = (rc == HOST_IGNORED)? hwhy_ignored : hwhy_failed;
2743 /* Scan the list for any hosts that are marked unusable because they have
2744 been explicitly ignored, and remove them from the list, as if they did not
2745 exist. If we end up with just a single, ignored host, flatten its fields as if
2746 nothing was found. */
2748 if (ignore_target_hosts != NULL)
2750 host_item *prev = NULL;
2751 for (h = host; h != last->next; h = h->next)
2754 if (h->why != hwhy_ignored) /* Non ignored host, just continue */
2756 else if (prev == NULL) /* First host is ignored */
2758 if (h != last) /* First is not last */
2760 if (h->next == last) last = h; /* Overwrite it with next */
2761 *h = *(h->next); /* and reprocess it. */
2762 goto REDO; /* C should have redo, like Perl */
2765 else /* Ignored host is not first - */
2767 prev->next = h->next;
2768 if (h == last) last = prev;
2772 if (host->why == hwhy_ignored) host->address = NULL;
2775 /* There is still one complication in the case of IPv6. Although the code above
2776 arranges that IPv6 addresses take precedence over IPv4 addresses for multihomed
2777 hosts, it doesn't do this for addresses that apply to different hosts with the
2778 same MX precedence, because the sorting on MX precedence happens first. So we
2779 have to make another pass to check for this case. We ensure that, within a
2780 single MX preference value, IPv6 addresses come first. This can separate the
2781 addresses of a multihomed host, but that should not matter. */
2786 for (h = host; h != last; h = h->next)
2789 host_item *next = h->next;
2790 if (h->mx != next->mx || /* If next is different MX value */
2791 (h->sort_key % 1000) < 500 || /* OR this one is IPv6 */
2792 (next->sort_key % 1000) >= 500) /* OR next is IPv4 */
2793 continue; /* move on to next */
2795 temp.next = next->next;
2803 /* When running in the test harness, we want the hosts always to be in the same
2804 order so that the debugging output is the same and can be compared. Having a
2805 fixed set of "random" numbers doesn't actually achieve this, because the RRs
2806 come back from the resolver in a random order, so the non-random random numbers
2807 get used in a different order. We therefore have to sort the hosts that have
2808 the same MX values. We chose do to this by their name and then by IP address.
2809 The fact that the sort is slow matters not - this is testing only! */
2811 if (running_in_test_harness)
2817 for (h = host; h != last; h = h->next)
2819 int c = Ustrcmp(h->name, h->next->name);
2820 if (c == 0) c = Ustrcmp(h->address, h->next->address);
2821 if (h->mx == h->next->mx && c > 0)
2823 host_item *next = h->next;
2824 host_item temp = *h;
2825 temp.next = next->next;
2836 /* Remove any duplicate IP addresses and then scan the list of hosts for any
2837 whose IP addresses are on the local host. If any are found, all hosts with the
2838 same or higher MX values are removed. However, if the local host has the lowest
2839 numbered MX, then HOST_FOUND_LOCAL is returned. Otherwise, if at least one host
2840 with an IP address is on the list, HOST_FOUND is returned. Otherwise,
2841 HOST_FIND_FAILED is returned, but in this case do not update the yield, as it
2842 might have been set to HOST_FIND_AGAIN just above here. If not, it will already
2843 be HOST_FIND_FAILED. */
2845 host_remove_duplicates(host, &last);
2846 rc = host_scan_for_local_hosts(host, &last, removed);
2847 if (rc != HOST_FIND_FAILED) yield = rc;
2849 DEBUG(D_host_lookup)
2851 if (fully_qualified_name != NULL)
2852 debug_printf("fully qualified name = %s\n", *fully_qualified_name);
2853 debug_printf("host_find_bydns yield = %s (%d); returned hosts:\n",
2854 (yield == HOST_FOUND)? "HOST_FOUND" :
2855 (yield == HOST_FOUND_LOCAL)? "HOST_FOUND_LOCAL" :
2856 (yield == HOST_FIND_AGAIN)? "HOST_FIND_AGAIN" :
2857 (yield == HOST_FIND_FAILED)? "HOST_FIND_FAILED" : "?",
2859 for (h = host; h != last->next; h = h->next)
2861 debug_printf(" %s %s MX=%d ", h->name,
2862 (h->address == NULL)? US"<null>" : h->address, h->mx);
2863 if (h->port != PORT_NONE) debug_printf("port=%d ", h->port);
2864 if (h->status >= hstatus_unusable) debug_printf("*");
2875 /*************************************************
2876 **************************************************
2877 * Stand-alone test program *
2878 **************************************************
2879 *************************************************/
2883 BOOL alldigits(uschar *buffer)
2885 if (!isdigit(*buffer)) return FALSE;
2886 if (*buffer == '0' && buffer[1] == 'x')
2889 while (isxdigit(*(++buffer)));
2891 else while (isdigit(*(++buffer)));
2892 return (*buffer == 0);
2895 int main(int argc, char **cargv)
2898 int whichrrs = HOST_FIND_BY_MX | HOST_FIND_BY_A;
2899 BOOL byname = FALSE;
2900 BOOL qualify_single = TRUE;
2901 BOOL search_parents = FALSE;
2902 uschar **argv = USS cargv;
2905 primary_hostname = US"";
2906 store_pool = POOL_MAIN;
2907 debug_selector = D_host_lookup|D_interface;
2908 debug_file = stdout;
2909 debug_fd = fileno(debug_file);
2911 printf("Exim stand-alone host functions test\n");
2913 host_find_interfaces();
2914 debug_selector = D_host_lookup | D_dns;
2916 if (argc > 1) primary_hostname = argv[1];
2918 /* So that debug level changes can be done first */
2920 dns_init(qualify_single, search_parents);
2922 printf("Testing host lookup\n");
2924 while (Ufgets(buffer, 256, stdin) != NULL)
2927 int len = Ustrlen(buffer);
2928 uschar *fully_qualified_name;
2930 while (len > 0 && isspace(buffer[len-1])) len--;
2933 if (Ustrcmp(buffer, "q") == 0) break;
2935 if (Ustrcmp(buffer, "byname") == 0) byname = TRUE;
2936 else if (Ustrcmp(buffer, "no_byname") == 0) byname = FALSE;
2937 else if (Ustrcmp(buffer, "a_only") == 0) whichrrs = HOST_FIND_BY_A;
2938 else if (Ustrcmp(buffer, "mx_only") == 0) whichrrs = HOST_FIND_BY_MX;
2939 else if (Ustrcmp(buffer, "srv_only") == 0) whichrrs = HOST_FIND_BY_SRV;
2940 else if (Ustrcmp(buffer, "srv+a") == 0)
2941 whichrrs = HOST_FIND_BY_SRV | HOST_FIND_BY_A;
2942 else if (Ustrcmp(buffer, "srv+mx") == 0)
2943 whichrrs = HOST_FIND_BY_SRV | HOST_FIND_BY_MX;
2944 else if (Ustrcmp(buffer, "srv+mx+a") == 0)
2945 whichrrs = HOST_FIND_BY_SRV | HOST_FIND_BY_MX | HOST_FIND_BY_A;
2946 else if (Ustrcmp(buffer, "qualify_single") == 0) qualify_single = TRUE;
2947 else if (Ustrcmp(buffer, "no_qualify_single") == 0) qualify_single = FALSE;
2948 else if (Ustrcmp(buffer, "search_parents") == 0) search_parents = TRUE;
2949 else if (Ustrcmp(buffer, "no_search_parents") == 0) search_parents = FALSE;
2950 else if (Ustrncmp(buffer, "retrans", 7) == 0)
2952 sscanf(CS(buffer+8), "%d", &dns_retrans);
2953 _res.retrans = dns_retrans;
2955 else if (Ustrncmp(buffer, "retry", 5) == 0)
2957 sscanf(CS(buffer+6), "%d", &dns_retry);
2958 _res.retry = dns_retry;
2960 else if (alldigits(buffer))
2962 debug_selector = Ustrtol(buffer, NULL, 0);
2963 _res.options &= ~RES_DEBUG;
2964 DEBUG(D_resolver) _res.options |= RES_DEBUG;
2968 int flags = whichrrs;
2974 h.status = hstatus_unknown;
2975 h.why = hwhy_unknown;
2978 if (qualify_single) flags |= HOST_FIND_QUALIFY_SINGLE;
2979 if (search_parents) flags |= HOST_FIND_SEARCH_PARENTS;
2982 host_find_byname(&h, NULL, &fully_qualified_name, TRUE)
2984 host_find_bydns(&h, NULL, flags, US"smtp", NULL, NULL,
2985 &fully_qualified_name, NULL);
2987 if (rc == HOST_FIND_FAILED) printf("Failed\n");
2988 else if (rc == HOST_FIND_AGAIN) printf("Again\n");
2989 else if (rc == HOST_FOUND_LOCAL) printf("Local\n");
2995 printf("Testing host_aton\n");
2997 while (Ufgets(buffer, 256, stdin) != NULL)
3001 int len = Ustrlen(buffer);
3003 while (len > 0 && isspace(buffer[len-1])) len--;
3006 if (Ustrcmp(buffer, "q") == 0) break;
3008 len = host_aton(buffer, x);
3009 printf("length = %d ", len);
3010 for (i = 0; i < len; i++)
3012 printf("%04x ", (x[i] >> 16) & 0xffff);
3013 printf("%04x ", x[i] & 0xffff);
3020 printf("Testing host_name_lookup\n");
3022 while (Ufgets(buffer, 256, stdin) != NULL)
3024 int len = Ustrlen(buffer);
3025 while (len > 0 && isspace(buffer[len-1])) len--;
3027 if (Ustrcmp(buffer, "q") == 0) break;
3028 sender_host_address = buffer;
3029 sender_host_name = NULL;
3030 sender_host_aliases = NULL;
3031 host_lookup_msg = US"";
3032 host_lookup_failed = FALSE;
3033 if (host_name_lookup() == FAIL) /* Debug causes printing */
3034 printf("Lookup failed:%s\n", host_lookup_msg);
3042 #endif /* STAND_ALONE */