1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
5 /* Copyright (c) University of Cambridge 1995 - 2012 */
6 /* See the file NOTICE for conditions of use and distribution. */
8 /* Functions for finding hosts, either by gethostbyname(), gethostbyaddr(), or
9 directly via the DNS. When IPv6 is supported, getipnodebyname() and
10 getipnodebyaddr() may be used instead of gethostbyname() and gethostbyaddr(),
11 if the newer functions are available. This module also contains various other
12 functions concerned with hosts and addresses, and a random number function,
13 used for randomizing hosts with equal MXs but available for use in other parts
20 /* Static variable for preserving the list of interface addresses in case it is
21 used more than once. */
23 static ip_address_item *local_interface_data = NULL;
26 #ifdef USE_INET_NTOA_FIX
27 /*************************************************
28 * Replacement for broken inet_ntoa() *
29 *************************************************/
31 /* On IRIX systems, gcc uses a different structure passing convention to the
32 native libraries. This causes inet_ntoa() to always yield 0.0.0.0 or
33 255.255.255.255. To get round this, we provide a private version of the
34 function here. It is used only if USE_INET_NTOA_FIX is set, which should happen
35 only when gcc is in use on an IRIX system. Code send to me by J.T. Breitner,
39 as seen in comp.sys.sgi.admin
41 August 2005: Apparently this is also needed for AIX systems; USE_INET_NTOA_FIX
42 should now be set for them as well.
44 Arguments: sa an in_addr structure
45 Returns: pointer to static text string
49 inet_ntoa(struct in_addr sa)
51 static uschar addr[20];
52 sprintf(addr, "%d.%d.%d.%d",
63 /*************************************************
64 * Random number generator *
65 *************************************************/
67 /* This is a simple pseudo-random number generator. It does not have to be
68 very good for the uses to which it is put. When running the regression tests,
69 start with a fixed seed.
71 If you need better, see vaguely_random_number() which is potentially stronger,
72 if a crypto library is available, but might end up just calling this instead.
75 limit: one more than the largest number required
77 Returns: a pseudo-random number in the range 0 to limit-1
81 random_number(int limit)
87 if (running_in_test_harness) random_seed = 42; else
89 int p = (int)getpid();
90 random_seed = (int)time(NULL) ^ ((p << 16) | p);
93 random_seed = 1103515245 * random_seed + 12345;
94 return (unsigned int)(random_seed >> 16) % limit;
97 /*************************************************
98 * Wrappers for logging lookup times *
99 *************************************************/
101 /* When the 'slow_lookup_log' variable is enabled, these wrappers will
102 write to the log file all (potential) dns lookups that take more than
103 slow_lookup_log milliseconds
107 log_long_lookup(const uschar * type, const uschar * data, unsigned long msec)
109 log_write(0, LOG_MAIN, "Long %s lookup for '%s': %lu msec",
114 /* returns the current system epoch time in milliseconds. */
118 struct timeval tmp_time;
119 unsigned long seconds, microseconds;
121 gettimeofday(&tmp_time, NULL);
122 seconds = (unsigned long) tmp_time.tv_sec;
123 microseconds = (unsigned long) tmp_time.tv_usec;
124 return seconds*1000 + microseconds/1000;
129 dns_lookup_timerwrap(dns_answer *dnsa, const uschar *name, int type,
130 const uschar **fully_qualified_name)
133 unsigned long time_msec;
135 if (!slow_lookup_log)
136 return dns_lookup(dnsa, name, type, fully_qualified_name);
138 time_msec = get_time_in_ms();
139 retval = dns_lookup(dnsa, name, type, fully_qualified_name);
140 if ((time_msec = get_time_in_ms() - time_msec) > slow_lookup_log)
141 log_long_lookup(US"name", name, time_msec);
146 /*************************************************
147 * Replace gethostbyname() when testing *
148 *************************************************/
150 /* This function is called instead of gethostbyname(), gethostbyname2(), or
151 getipnodebyname() when running in the test harness. . It also
152 recognizes an unqualified "localhost" and forces it to the appropriate loopback
153 address. IP addresses are treated as literals. For other names, it uses the DNS
154 to find the host name. In the test harness, this means it will access only the
158 name the host name or a textual IP address
159 af AF_INET or AF_INET6
160 error_num where to put an error code:
161 HOST_NOT_FOUND/TRY_AGAIN/NO_RECOVERY/NO_DATA
163 Returns: a hostent structure or NULL for an error
166 static struct hostent *
167 host_fake_gethostbyname(const uschar *name, int af, int *error_num)
170 int alen = (af == AF_INET)? sizeof(struct in_addr):sizeof(struct in6_addr);
172 int alen = sizeof(struct in_addr);
176 const uschar *lname = name;
179 struct hostent *yield;
185 debug_printf("using host_fake_gethostbyname for %s (%s)\n", name,
186 (af == AF_INET)? "IPv4" : "IPv6");
188 /* Handle unqualified "localhost" */
190 if (Ustrcmp(name, "localhost") == 0)
191 lname = (af == AF_INET)? US"127.0.0.1" : US"::1";
193 /* Handle a literal IP address */
195 ipa = string_is_ip_address(lname, NULL);
198 if ((ipa == 4 && af == AF_INET) ||
199 (ipa == 6 && af == AF_INET6))
203 yield = store_get(sizeof(struct hostent));
204 alist = store_get(2 * sizeof(char *));
205 adds = store_get(alen);
206 yield->h_name = CS name;
207 yield->h_aliases = NULL;
208 yield->h_addrtype = af;
209 yield->h_length = alen;
210 yield->h_addr_list = CSS alist;
212 n = host_aton(lname, x);
213 for (i = 0; i < n; i++)
216 *adds++ = (y >> 24) & 255;
217 *adds++ = (y >> 16) & 255;
218 *adds++ = (y >> 8) & 255;
224 /* Wrong kind of literal address */
228 *error_num = HOST_NOT_FOUND;
233 /* Handle a host name */
237 int type = (af == AF_INET)? T_A:T_AAAA;
238 int rc = dns_lookup_timerwrap(&dnsa, lname, type, NULL);
241 lookup_dnssec_authenticated = NULL;
245 case DNS_SUCCEED: break;
246 case DNS_NOMATCH: *error_num = HOST_NOT_FOUND; return NULL;
247 case DNS_NODATA: *error_num = NO_DATA; return NULL;
248 case DNS_AGAIN: *error_num = TRY_AGAIN; return NULL;
250 case DNS_FAIL: *error_num = NO_RECOVERY; return NULL;
253 for (rr = dns_next_rr(&dnsa, &dnss, RESET_ANSWERS);
255 rr = dns_next_rr(&dnsa, &dnss, RESET_NEXT))
256 if (rr->type == type)
259 yield = store_get(sizeof(struct hostent));
260 alist = store_get((count + 1) * sizeof(char **));
261 adds = store_get(count *alen);
263 yield->h_name = CS name;
264 yield->h_aliases = NULL;
265 yield->h_addrtype = af;
266 yield->h_length = alen;
267 yield->h_addr_list = CSS alist;
269 for (rr = dns_next_rr(&dnsa, &dnss, RESET_ANSWERS);
271 rr = dns_next_rr(&dnsa, &dnss, RESET_NEXT))
276 if (rr->type != type) continue;
277 if (!(da = dns_address_from_rr(&dnsa, rr))) break;
279 n = host_aton(da->address, x);
280 for (i = 0; i < n; i++)
283 *adds++ = (y >> 24) & 255;
284 *adds++ = (y >> 16) & 255;
285 *adds++ = (y >> 8) & 255;
297 /*************************************************
298 * Build chain of host items from list *
299 *************************************************/
301 /* This function builds a chain of host items from a textual list of host
302 names. It does not do any lookups. If randomize is true, the chain is build in
303 a randomized order. There may be multiple groups of independently randomized
304 hosts; they are delimited by a host name consisting of just "+".
307 anchor anchor for the chain
309 randomize TRUE for randomizing
315 host_build_hostlist(host_item **anchor, const uschar *list, BOOL randomize)
318 int fake_mx = MX_NONE; /* This value is actually -1 */
321 if (list == NULL) return;
322 if (randomize) fake_mx--; /* Start at -2 for randomizing */
326 while ((name = string_nextinlist(&list, &sep, NULL, 0)) != NULL)
330 if (name[0] == '+' && name[1] == 0) /* "+" delimits a randomized group */
331 { /* ignore if not randomizing */
332 if (randomize) fake_mx--;
336 h = store_get(sizeof(host_item));
341 h->sort_key = randomize? (-fake_mx)*1000 + random_number(1000) : 0;
342 h->status = hstatus_unknown;
343 h->why = hwhy_unknown;
353 host_item *hh = *anchor;
354 if (h->sort_key < hh->sort_key)
361 while (hh->next != NULL && h->sort_key >= (hh->next)->sort_key)
374 /*************************************************
375 * Extract port from address string *
376 *************************************************/
378 /* In the spool file, and in the -oMa and -oMi options, a host plus port is
379 given as an IP address followed by a dot and a port number. This function
382 An alternative format for the -oMa and -oMi options is [ip address]:port which
383 is what Exim 4 uses for output, because it seems to becoming commonly used,
384 whereas the dot form confuses some programs/people. So we recognize that form
388 address points to the string; if there is a port, the '.' in the string
389 is overwritten with zero to terminate the address; if the string
390 is in the [xxx]:ppp format, the address is shifted left and the
393 Returns: 0 if there is no port, else the port number. If there's a syntax
394 error, leave the incoming address alone, and return 0.
398 host_address_extract_port(uschar *address)
403 /* Handle the "bracketed with colon on the end" format */
407 uschar *rb = address + 1;
408 while (*rb != 0 && *rb != ']') rb++;
409 if (*rb++ == 0) return 0; /* Missing ]; leave invalid address */
412 port = Ustrtol(rb + 1, &endptr, 10);
413 if (*endptr != 0) return 0; /* Invalid port; leave invalid address */
415 else if (*rb != 0) return 0; /* Bad syntax; leave invalid address */
416 memmove(address, address + 1, rb - address - 2);
420 /* Handle the "dot on the end" format */
424 int skip = -3; /* Skip 3 dots in IPv4 addresses */
426 while (*(++address) != 0)
429 if (ch == ':') skip = 0; /* Skip 0 dots in IPv6 addresses */
430 else if (ch == '.' && skip++ >= 0) break;
432 if (*address == 0) return 0;
433 port = Ustrtol(address + 1, &endptr, 10);
434 if (*endptr != 0) return 0; /* Invalid port; leave invalid address */
442 /*************************************************
443 * Get port from a host item's name *
444 *************************************************/
446 /* This function is called when finding the IP address for a host that is in a
447 list of hosts explicitly configured, such as in the manualroute router, or in a
448 fallback hosts list. We see if there is a port specification at the end of the
449 host name, and if so, remove it. A minimum length of 3 is required for the
450 original name; nothing shorter is recognized as having a port.
452 We test for a name ending with a sequence of digits; if preceded by colon we
453 have a port if the character before the colon is ] and the name starts with [
454 or if there are no other colons in the name (i.e. it's not an IPv6 address).
456 Arguments: pointer to the host item
457 Returns: a port number or PORT_NONE
461 host_item_get_port(host_item *h)
465 int len = Ustrlen(h->name);
467 if (len < 3 || (p = h->name + len - 1, !isdigit(*p))) return PORT_NONE;
469 /* Extract potential port number */
474 while (p > h->name + 1 && isdigit(*p))
476 port += (*p-- - '0') * x;
480 /* The smallest value of p at this point is h->name + 1. */
482 if (*p != ':') return PORT_NONE;
484 if (p[-1] == ']' && h->name[0] == '[')
485 h->name = string_copyn(h->name + 1, p - h->name - 2);
486 else if (Ustrchr(h->name, ':') == p)
487 h->name = string_copyn(h->name, p - h->name);
488 else return PORT_NONE;
490 DEBUG(D_route|D_host_lookup) debug_printf("host=%s port=%d\n", h->name, port);
496 #ifndef STAND_ALONE /* Omit when standalone testing */
498 /*************************************************
499 * Build sender_fullhost and sender_rcvhost *
500 *************************************************/
502 /* This function is called when sender_host_name and/or sender_helo_name
503 have been set. Or might have been set - for a local message read off the spool
504 they won't be. In that case, do nothing. Otherwise, set up the fullhost string
507 (a) No sender_host_name or sender_helo_name: "[ip address]"
508 (b) Just sender_host_name: "host_name [ip address]"
509 (c) Just sender_helo_name: "(helo_name) [ip address]" unless helo is IP
510 in which case: "[ip address}"
511 (d) The two are identical: "host_name [ip address]" includes helo = IP
512 (e) The two are different: "host_name (helo_name) [ip address]"
514 If log_incoming_port is set, the sending host's port number is added to the IP
517 This function also builds sender_rcvhost for use in Received: lines, whose
518 syntax is a bit different. This value also includes the RFC 1413 identity.
519 There wouldn't be two different variables if I had got all this right in the
522 Because this data may survive over more than one incoming SMTP message, it has
523 to be in permanent store.
530 host_build_sender_fullhost(void)
532 BOOL show_helo = TRUE;
535 int old_pool = store_pool;
537 if (sender_host_address == NULL) return;
539 store_pool = POOL_PERM;
541 /* Set up address, with or without the port. After discussion, it seems that
542 the only format that doesn't cause trouble is [aaaa]:pppp. However, we can't
543 use this directly as the first item for Received: because it ain't an RFC 2822
546 address = string_sprintf("[%s]:%d", sender_host_address, sender_host_port);
547 if ((log_extra_selector & LX_incoming_port) == 0 || sender_host_port <= 0)
548 *(Ustrrchr(address, ':')) = 0;
550 /* If there's no EHLO/HELO data, we can't show it. */
552 if (sender_helo_name == NULL) show_helo = FALSE;
554 /* If HELO/EHLO was followed by an IP literal, it's messy because of two
555 features of IPv6. Firstly, there's the "IPv6:" prefix (Exim is liberal and
556 doesn't require this, for historical reasons). Secondly, IPv6 addresses may not
557 be given in canonical form, so we have to canonicize them before comparing. As
558 it happens, the code works for both IPv4 and IPv6. */
560 else if (sender_helo_name[0] == '[' &&
561 sender_helo_name[(len=Ustrlen(sender_helo_name))-1] == ']')
566 if (strncmpic(sender_helo_name + 1, US"IPv6:", 5) == 0) offset += 5;
567 if (strncmpic(sender_helo_name + 1, US"IPv4:", 5) == 0) offset += 5;
569 helo_ip = string_copyn(sender_helo_name + offset, len - offset - 1);
571 if (string_is_ip_address(helo_ip, NULL) != 0)
575 uschar ipx[48], ipy[48]; /* large enough for full IPv6 */
577 sizex = host_aton(helo_ip, x);
578 sizey = host_aton(sender_host_address, y);
580 (void)host_nmtoa(sizex, x, -1, ipx, ':');
581 (void)host_nmtoa(sizey, y, -1, ipy, ':');
583 if (strcmpic(ipx, ipy) == 0) show_helo = FALSE;
587 /* Host name is not verified */
589 if (sender_host_name == NULL)
591 uschar *portptr = Ustrstr(address, "]:");
594 int adlen; /* Sun compiler doesn't like ++ in initializers */
596 adlen = (portptr == NULL)? Ustrlen(address) : (++portptr - address);
597 sender_fullhost = (sender_helo_name == NULL)? address :
598 string_sprintf("(%s) %s", sender_helo_name, address);
600 sender_rcvhost = string_cat(NULL, &size, &ptr, address, adlen);
602 if (sender_ident != NULL || show_helo || portptr != NULL)
605 sender_rcvhost = string_cat(sender_rcvhost, &size, &ptr, US" (", 2);
609 sender_rcvhost = string_append(sender_rcvhost, &size, &ptr, 2, US"port=",
613 sender_rcvhost = string_append(sender_rcvhost, &size, &ptr, 2,
614 (firstptr == ptr)? US"helo=" : US" helo=", sender_helo_name);
616 if (sender_ident != NULL)
617 sender_rcvhost = string_append(sender_rcvhost, &size, &ptr, 2,
618 (firstptr == ptr)? US"ident=" : US" ident=", sender_ident);
620 sender_rcvhost = string_cat(sender_rcvhost, &size, &ptr, US")", 1);
623 sender_rcvhost[ptr] = 0; /* string_cat() always leaves room */
625 /* Release store, because string_cat allocated a minimum of 100 bytes that
626 are rarely completely used. */
628 store_reset(sender_rcvhost + ptr + 1);
631 /* Host name is known and verified. Unless we've already found that the HELO
632 data matches the IP address, compare it with the name. */
636 if (show_helo && strcmpic(sender_host_name, sender_helo_name) == 0)
641 sender_fullhost = string_sprintf("%s (%s) %s", sender_host_name,
642 sender_helo_name, address);
643 sender_rcvhost = (sender_ident == NULL)?
644 string_sprintf("%s (%s helo=%s)", sender_host_name,
645 address, sender_helo_name) :
646 string_sprintf("%s\n\t(%s helo=%s ident=%s)", sender_host_name,
647 address, sender_helo_name, sender_ident);
651 sender_fullhost = string_sprintf("%s %s", sender_host_name, address);
652 sender_rcvhost = (sender_ident == NULL)?
653 string_sprintf("%s (%s)", sender_host_name, address) :
654 string_sprintf("%s (%s ident=%s)", sender_host_name, address,
659 store_pool = old_pool;
661 DEBUG(D_host_lookup) debug_printf("sender_fullhost = %s\n", sender_fullhost);
662 DEBUG(D_host_lookup) debug_printf("sender_rcvhost = %s\n", sender_rcvhost);
667 /*************************************************
668 * Build host+ident message *
669 *************************************************/
671 /* Used when logging rejections and various ACL and SMTP incidents. The text
672 return depends on whether sender_fullhost and sender_ident are set or not:
674 no ident, no host => U=unknown
675 no ident, host set => H=sender_fullhost
676 ident set, no host => U=ident
677 ident set, host set => H=sender_fullhost U=ident
680 useflag TRUE if first item to be flagged (H= or U=); if there are two
681 items, the second is always flagged
683 Returns: pointer to a string in big_buffer
687 host_and_ident(BOOL useflag)
689 if (sender_fullhost == NULL)
691 (void)string_format(big_buffer, big_buffer_size, "%s%s", useflag? "U=" : "",
692 (sender_ident == NULL)? US"unknown" : sender_ident);
696 uschar *flag = useflag? US"H=" : US"";
697 uschar *iface = US"";
698 if ((log_extra_selector & LX_incoming_interface) != 0 &&
699 interface_address != NULL)
700 iface = string_sprintf(" I=[%s]:%d", interface_address, interface_port);
701 if (sender_ident == NULL)
702 (void)string_format(big_buffer, big_buffer_size, "%s%s%s",
703 flag, sender_fullhost, iface);
705 (void)string_format(big_buffer, big_buffer_size, "%s%s%s U=%s",
706 flag, sender_fullhost, iface, sender_ident);
711 #endif /* STAND_ALONE */
716 /*************************************************
717 * Build list of local interfaces *
718 *************************************************/
720 /* This function interprets the contents of the local_interfaces or
721 extra_local_interfaces options, and creates an ip_address_item block for each
722 item on the list. There is no special interpretation of any IP addresses; in
723 particular, 0.0.0.0 and ::0 are returned without modification. If any address
724 includes a port, it is set in the block. Otherwise the port value is set to
729 name the name of the option being expanded
731 Returns: a chain of ip_address_items, each containing to a textual
732 version of an IP address, and a port number (host order) or
733 zero if no port was given with the address
737 host_build_ifacelist(const uschar *list, uschar *name)
742 ip_address_item *yield = NULL;
743 ip_address_item *last = NULL;
744 ip_address_item *next;
746 while ((s = string_nextinlist(&list, &sep, buffer, sizeof(buffer))) != NULL)
749 int port = host_address_extract_port(s); /* Leaves just the IP address */
750 if ((ipv = string_is_ip_address(s, NULL)) == 0)
751 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "Malformed IP address \"%s\" in %s",
754 /* Skip IPv6 addresses if IPv6 is disabled. */
756 if (disable_ipv6 && ipv == 6) continue;
758 /* This use of strcpy() is OK because we have checked that s is a valid IP
759 address above. The field in the ip_address_item is large enough to hold an
762 next = store_get(sizeof(ip_address_item));
764 Ustrcpy(next->address, s);
766 next->v6_include_v4 = FALSE;
768 if (yield == NULL) yield = last = next; else
782 /*************************************************
783 * Find addresses on local interfaces *
784 *************************************************/
786 /* This function finds the addresses of local IP interfaces. These are used
787 when testing for routing to the local host. As the function may be called more
788 than once, the list is preserved in permanent store, pointed to by a static
789 variable, to save doing the work more than once per process.
791 The generic list of interfaces is obtained by calling host_build_ifacelist()
792 for local_interfaces and extra_local_interfaces. This list scanned to remove
793 duplicates (which may exist with different ports - not relevant here). If
794 either of the wildcard IP addresses (0.0.0.0 and ::0) are encountered, they are
795 replaced by the appropriate (IPv4 or IPv6) list of actual local interfaces,
796 obtained from os_find_running_interfaces().
799 Returns: a chain of ip_address_items, each containing to a textual
800 version of an IP address; the port numbers are not relevant
804 /* First, a local subfunction to add an interface to a list in permanent store,
805 but only if there isn't a previous copy of that address on the list. */
807 static ip_address_item *
808 add_unique_interface(ip_address_item *list, ip_address_item *ipa)
810 ip_address_item *ipa2;
811 for (ipa2 = list; ipa2 != NULL; ipa2 = ipa2->next)
812 if (Ustrcmp(ipa2->address, ipa->address) == 0) return list;
813 ipa2 = store_get_perm(sizeof(ip_address_item));
820 /* This is the globally visible function */
823 host_find_interfaces(void)
825 ip_address_item *running_interfaces = NULL;
827 if (local_interface_data == NULL)
829 void *reset_item = store_get(0);
830 ip_address_item *dlist = host_build_ifacelist(CUS local_interfaces,
831 US"local_interfaces");
832 ip_address_item *xlist = host_build_ifacelist(CUS extra_local_interfaces,
833 US"extra_local_interfaces");
834 ip_address_item *ipa;
836 if (dlist == NULL) dlist = xlist; else
838 for (ipa = dlist; ipa->next != NULL; ipa = ipa->next);
842 for (ipa = dlist; ipa != NULL; ipa = ipa->next)
844 if (Ustrcmp(ipa->address, "0.0.0.0") == 0 ||
845 Ustrcmp(ipa->address, "::0") == 0)
847 ip_address_item *ipa2;
848 BOOL ipv6 = ipa->address[0] == ':';
849 if (running_interfaces == NULL)
850 running_interfaces = os_find_running_interfaces();
851 for (ipa2 = running_interfaces; ipa2 != NULL; ipa2 = ipa2->next)
853 if ((Ustrchr(ipa2->address, ':') != NULL) == ipv6)
854 local_interface_data = add_unique_interface(local_interface_data,
860 local_interface_data = add_unique_interface(local_interface_data, ipa);
863 debug_printf("Configured local interface: address=%s", ipa->address);
864 if (ipa->port != 0) debug_printf(" port=%d", ipa->port);
869 store_reset(reset_item);
872 return local_interface_data;
879 /*************************************************
880 * Convert network IP address to text *
881 *************************************************/
883 /* Given an IPv4 or IPv6 address in binary, convert it to a text
884 string and return the result in a piece of new store. The address can
885 either be given directly, or passed over in a sockaddr structure. Note
886 that this isn't the converse of host_aton() because of byte ordering
887 differences. See host_nmtoa() below.
890 type if < 0 then arg points to a sockaddr, else
891 either AF_INET or AF_INET6
892 arg points to a sockaddr if type is < 0, or
893 points to an IPv4 address (32 bits), or
894 points to an IPv6 address (128 bits),
895 in both cases, in network byte order
896 buffer if NULL, the result is returned in gotten store;
897 else points to a buffer to hold the answer
898 portptr points to where to put the port number, if non NULL; only
901 Returns: pointer to character string
905 host_ntoa(int type, const void *arg, uschar *buffer, int *portptr)
909 /* The new world. It is annoying that we have to fish out the address from
910 different places in the block, depending on what kind of address it is. It
911 is also a pain that inet_ntop() returns a const uschar *, whereas the IPv4
912 function inet_ntoa() returns just uschar *, and some picky compilers insist
913 on warning if one assigns a const uschar * to a uschar *. Hence the casts. */
916 uschar addr_buffer[46];
919 int family = ((struct sockaddr *)arg)->sa_family;
920 if (family == AF_INET6)
922 struct sockaddr_in6 *sk = (struct sockaddr_in6 *)arg;
923 yield = (uschar *)inet_ntop(family, &(sk->sin6_addr), CS addr_buffer,
924 sizeof(addr_buffer));
925 if (portptr != NULL) *portptr = ntohs(sk->sin6_port);
929 struct sockaddr_in *sk = (struct sockaddr_in *)arg;
930 yield = (uschar *)inet_ntop(family, &(sk->sin_addr), CS addr_buffer,
931 sizeof(addr_buffer));
932 if (portptr != NULL) *portptr = ntohs(sk->sin_port);
937 yield = (uschar *)inet_ntop(type, arg, CS addr_buffer, sizeof(addr_buffer));
940 /* If the result is a mapped IPv4 address, show it in V4 format. */
942 if (Ustrncmp(yield, "::ffff:", 7) == 0) yield += 7;
944 #else /* HAVE_IPV6 */
950 yield = US inet_ntoa(((struct sockaddr_in *)arg)->sin_addr);
951 if (portptr != NULL) *portptr = ntohs(((struct sockaddr_in *)arg)->sin_port);
954 yield = US inet_ntoa(*((struct in_addr *)arg));
957 /* If there is no buffer, put the string into some new store. */
959 if (buffer == NULL) return string_copy(yield);
961 /* Callers of this function with a non-NULL buffer must ensure that it is
962 large enough to hold an IPv6 address, namely, at least 46 bytes. That's what
963 makes this use of strcpy() OK. */
965 Ustrcpy(buffer, yield);
972 /*************************************************
973 * Convert address text to binary *
974 *************************************************/
976 /* Given the textual form of an IP address, convert it to binary in an
977 array of ints. IPv4 addresses occupy one int; IPv6 addresses occupy 4 ints.
978 The result has the first byte in the most significant byte of the first int. In
979 other words, the result is not in network byte order, but in host byte order.
980 As a result, this is not the converse of host_ntoa(), which expects network
981 byte order. See host_nmtoa() below.
984 address points to the textual address, checked for syntax
985 bin points to an array of 4 ints
987 Returns: the number of ints used
991 host_aton(const uschar *address, int *bin)
996 /* Handle IPv6 address, which may end with an IPv4 address. It may also end
997 with a "scope", introduced by a percent sign. This code is NOT enclosed in #if
998 HAVE_IPV6 in order that IPv6 addresses are recognized even if IPv6 is not
1001 if (Ustrchr(address, ':') != NULL)
1003 const uschar *p = address;
1004 const uschar *component[8];
1005 BOOL ipv4_ends = FALSE;
1011 /* If the address starts with a colon, it will start with two colons.
1012 Just lose the first one, which will leave a null first component. */
1016 /* Split the address into components separated by colons. The input address
1017 is supposed to be checked for syntax. There was a case where this was
1018 overlooked; to guard against that happening again, check here and crash if
1019 there are too many components. */
1021 while (*p != 0 && *p != '%')
1023 int len = Ustrcspn(p, ":%");
1024 if (len == 0) nulloffset = ci;
1025 if (ci > 7) log_write(0, LOG_MAIN|LOG_PANIC_DIE,
1026 "Internal error: invalid IPv6 address \"%s\" passed to host_aton()",
1028 component[ci++] = p;
1033 /* If the final component contains a dot, it is a trailing v4 address.
1034 As the syntax is known to be checked, just set up for a trailing
1035 v4 address and restrict the v6 part to 6 components. */
1037 if (Ustrchr(component[ci-1], '.') != NULL)
1039 address = component[--ci];
1045 /* If there are fewer than 6 or 8 components, we have to insert some
1046 more empty ones in the middle. */
1050 int insert_count = v6count - ci;
1051 for (i = v6count-1; i > nulloffset + insert_count; i--)
1052 component[i] = component[i - insert_count];
1053 while (i > nulloffset) component[i--] = US"";
1056 /* Now turn the components into binary in pairs and bung them
1057 into the vector of ints. */
1059 for (i = 0; i < v6count; i += 2)
1060 bin[i/2] = (Ustrtol(component[i], NULL, 16) << 16) +
1061 Ustrtol(component[i+1], NULL, 16);
1063 /* If there was no terminating v4 component, we are done. */
1065 if (!ipv4_ends) return 4;
1068 /* Handle IPv4 address */
1070 (void)sscanf(CS address, "%d.%d.%d.%d", x, x+1, x+2, x+3);
1071 bin[v4offset] = (x[0] << 24) + (x[1] << 16) + (x[2] << 8) + x[3];
1076 /*************************************************
1077 * Apply mask to an IP address *
1078 *************************************************/
1080 /* Mask an address held in 1 or 4 ints, with the ms bit in the ms bit of the
1084 count the number of ints
1085 binary points to the ints to be masked
1086 mask the count of ms bits to leave, or -1 if no masking
1092 host_mask(int count, int *binary, int mask)
1095 if (mask < 0) mask = 99999;
1096 for (i = 0; i < count; i++)
1099 if (mask == 0) wordmask = 0;
1102 wordmask = (-1) << (32 - mask);
1110 binary[i] &= wordmask;
1117 /*************************************************
1118 * Convert masked IP address in ints to text *
1119 *************************************************/
1121 /* We can't use host_ntoa() because it assumes the binary values are in network
1122 byte order, and these are the result of host_aton(), which puts them in ints in
1123 host byte order. Also, we really want IPv6 addresses to be in a canonical
1124 format, so we output them with no abbreviation. In a number of cases we can't
1125 use the normal colon separator in them because it terminates keys in lsearch
1126 files, so we want to use dot instead. There's an argument that specifies what
1127 to use for IPv6 addresses.
1130 count 1 or 4 (number of ints)
1131 binary points to the ints
1132 mask mask value; if < 0 don't add to result
1133 buffer big enough to hold the result
1134 sep component separator character for IPv6 addresses
1136 Returns: the number of characters placed in buffer, not counting
1141 host_nmtoa(int count, int *binary, int mask, uschar *buffer, int sep)
1144 uschar *tt = buffer;
1149 for (i = 24; i >= 0; i -= 8)
1151 sprintf(CS tt, "%d.", (j >> i) & 255);
1157 for (i = 0; i < 4; i++)
1160 sprintf(CS tt, "%04x%c%04x%c", (j >> 16) & 0xffff, sep, j & 0xffff, sep);
1165 tt--; /* lose final separator */
1171 sprintf(CS tt, "/%d", mask);
1180 /*************************************************
1181 * Check port for tls_on_connect *
1182 *************************************************/
1184 /* This function checks whether a given incoming port is configured for tls-
1185 on-connect. It is called from the daemon and from inetd handling. If the global
1186 option tls_on_connect is already set, all ports operate this way. Otherwise, we
1187 check the tls_on_connect_ports option for a list of ports.
1189 Argument: a port number
1190 Returns: TRUE or FALSE
1194 host_is_tls_on_connect_port(int port)
1198 const uschar *list = tls_in.on_connect_ports;
1202 if (tls_in.on_connect) return TRUE;
1204 while ((s = string_nextinlist(&list, &sep, buffer, sizeof(buffer))))
1205 if (Ustrtol(s, &end, 10) == port)
1213 /*************************************************
1214 * Check whether host is in a network *
1215 *************************************************/
1217 /* This function checks whether a given IP address matches a pattern that
1218 represents either a single host, or a network (using CIDR notation). The caller
1219 of this function must check the syntax of the arguments before calling it.
1222 host string representation of the ip-address to check
1223 net string representation of the network, with optional CIDR mask
1224 maskoffset offset to the / that introduces the mask in the key
1225 zero if there is no mask
1228 TRUE the host is inside the network
1229 FALSE the host is NOT inside the network
1233 host_is_in_net(const uschar *host, const uschar *net, int maskoffset)
1239 int size = host_aton(net, address);
1242 /* No mask => all bits to be checked */
1244 if (maskoffset == 0) mlen = 99999; /* Big number */
1245 else mlen = Uatoi(net + maskoffset + 1);
1247 /* Convert the incoming address to binary. */
1249 insize = host_aton(host, incoming);
1251 /* Convert IPv4 addresses given in IPv6 compatible mode, which represent
1252 connections from IPv4 hosts to IPv6 hosts, that is, addresses of the form
1253 ::ffff:<v4address>, to IPv4 format. */
1255 if (insize == 4 && incoming[0] == 0 && incoming[1] == 0 &&
1256 incoming[2] == 0xffff)
1259 incoming[0] = incoming[3];
1262 /* No match if the sizes don't agree. */
1264 if (insize != size) return FALSE;
1266 /* Else do the masked comparison. */
1268 for (i = 0; i < size; i++)
1271 if (mlen == 0) mask = 0;
1274 mask = (-1) << (32 - mlen);
1282 if ((incoming[i] & mask) != (address[i] & mask)) return FALSE;
1290 /*************************************************
1291 * Scan host list for local hosts *
1292 *************************************************/
1294 /* Scan through a chain of addresses and check whether any of them is the
1295 address of an interface on the local machine. If so, remove that address and
1296 any previous ones with the same MX value, and all subsequent ones (which will
1297 have greater or equal MX values) from the chain. Note: marking them as unusable
1298 is NOT the right thing to do because it causes the hosts not to be used for
1299 other domains, for which they may well be correct.
1301 The hosts may be part of a longer chain; we only process those between the
1302 initial pointer and the "last" pointer.
1304 There is also a list of "pseudo-local" host names which are checked against the
1305 host names. Any match causes that host item to be treated the same as one which
1306 matches a local IP address.
1308 If the very first host is a local host, then all MX records had a precedence
1309 greater than or equal to that of the local host. Either there's a problem in
1310 the DNS, or an apparently remote name turned out to be an abbreviation for the
1311 local host. Give a specific return code, and let the caller decide what to do.
1312 Otherwise, give a success code if at least one host address has been found.
1315 host pointer to the first host in the chain
1316 lastptr pointer to pointer to the last host in the chain (may be updated)
1317 removed if not NULL, set TRUE if some local addresses were removed
1321 HOST_FOUND if there is at least one host with an IP address on the chain
1322 and an MX value less than any MX value associated with the
1324 HOST_FOUND_LOCAL if a local host is among the lowest-numbered MX hosts; when
1325 the host addresses were obtained from A records or
1326 gethostbyname(), the MX values are set to -1.
1327 HOST_FIND_FAILED if no valid hosts with set IP addresses were found
1331 host_scan_for_local_hosts(host_item *host, host_item **lastptr, BOOL *removed)
1333 int yield = HOST_FIND_FAILED;
1334 host_item *last = *lastptr;
1335 host_item *prev = NULL;
1338 if (removed != NULL) *removed = FALSE;
1340 if (local_interface_data == NULL) local_interface_data = host_find_interfaces();
1342 for (h = host; h != last->next; h = h->next)
1345 if (hosts_treat_as_local != NULL)
1348 const uschar *save = deliver_domain;
1349 deliver_domain = h->name; /* set $domain */
1350 rc = match_isinlist(string_copylc(h->name), CUSS &hosts_treat_as_local, 0,
1351 &domainlist_anchor, NULL, MCL_DOMAIN, TRUE, NULL);
1352 deliver_domain = save;
1353 if (rc == OK) goto FOUND_LOCAL;
1357 /* It seems that on many operating systems, 0.0.0.0 is treated as a synonym
1358 for 127.0.0.1 and refers to the local host. We therefore force it always to
1359 be treated as local. */
1361 if (h->address != NULL)
1363 ip_address_item *ip;
1364 if (Ustrcmp(h->address, "0.0.0.0") == 0) goto FOUND_LOCAL;
1365 for (ip = local_interface_data; ip != NULL; ip = ip->next)
1366 if (Ustrcmp(h->address, ip->address) == 0) goto FOUND_LOCAL;
1367 yield = HOST_FOUND; /* At least one remote address has been found */
1370 /* Update prev to point to the last host item before any that have
1371 the same MX value as the one we have just considered. */
1373 if (h->next == NULL || h->next->mx != h->mx) prev = h;
1376 return yield; /* No local hosts found: return HOST_FOUND or HOST_FIND_FAILED */
1378 /* A host whose IP address matches a local IP address, or whose name matches
1379 something in hosts_treat_as_local has been found. */
1385 HDEBUG(D_host_lookup) debug_printf((h->mx >= 0)?
1386 "local host has lowest MX\n" :
1387 "local host found for non-MX address\n");
1388 return HOST_FOUND_LOCAL;
1391 HDEBUG(D_host_lookup)
1393 debug_printf("local host in host list - removed hosts:\n");
1394 for (h = prev->next; h != last->next; h = h->next)
1395 debug_printf(" %s %s %d\n", h->name, h->address, h->mx);
1398 if (removed != NULL) *removed = TRUE;
1399 prev->next = last->next;
1407 /*************************************************
1408 * Remove duplicate IPs in host list *
1409 *************************************************/
1411 /* You would think that administrators could set up their DNS records so that
1412 one ended up with a list of unique IP addresses after looking up A or MX
1413 records, but apparently duplication is common. So we scan such lists and
1414 remove the later duplicates. Note that we may get lists in which some host
1415 addresses are not set.
1418 host pointer to the first host in the chain
1419 lastptr pointer to pointer to the last host in the chain (may be updated)
1425 host_remove_duplicates(host_item *host, host_item **lastptr)
1427 while (host != *lastptr)
1429 if (host->address != NULL)
1431 host_item *h = host;
1432 while (h != *lastptr)
1434 if (h->next->address != NULL &&
1435 Ustrcmp(h->next->address, host->address) == 0)
1437 DEBUG(D_host_lookup) debug_printf("duplicate IP address %s (MX=%d) "
1438 "removed\n", host->address, h->next->mx);
1439 if (h->next == *lastptr) *lastptr = h;
1440 h->next = h->next->next;
1445 /* If the last item was removed, host may have become == *lastptr */
1446 if (host != *lastptr) host = host->next;
1453 /*************************************************
1454 * Find sender host name by gethostbyaddr() *
1455 *************************************************/
1457 /* This used to be the only way it was done, but it turns out that not all
1458 systems give aliases for calls to gethostbyaddr() - or one of the modern
1459 equivalents like getipnodebyaddr(). Fortunately, multiple PTR records are rare,
1460 but they can still exist. This function is now used only when a DNS lookup of
1461 the IP address fails, in order to give access to /etc/hosts.
1464 Returns: OK, DEFER, FAIL
1468 host_name_lookup_byaddr(void)
1472 struct hostent *hosts;
1473 struct in_addr addr;
1474 unsigned long time_msec;
1476 if (slow_lookup_log) time_msec = get_time_in_ms();
1478 /* Lookup on IPv6 system */
1481 if (Ustrchr(sender_host_address, ':') != NULL)
1483 struct in6_addr addr6;
1484 if (inet_pton(AF_INET6, CS sender_host_address, &addr6) != 1)
1485 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "unable to parse \"%s\" as an "
1486 "IPv6 address", sender_host_address);
1487 #if HAVE_GETIPNODEBYADDR
1488 hosts = getipnodebyaddr(CS &addr6, sizeof(addr6), AF_INET6, &h_errno);
1490 hosts = gethostbyaddr(CS &addr6, sizeof(addr6), AF_INET6);
1495 if (inet_pton(AF_INET, CS sender_host_address, &addr) != 1)
1496 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "unable to parse \"%s\" as an "
1497 "IPv4 address", sender_host_address);
1498 #if HAVE_GETIPNODEBYADDR
1499 hosts = getipnodebyaddr(CS &addr, sizeof(addr), AF_INET, &h_errno);
1501 hosts = gethostbyaddr(CS &addr, sizeof(addr), AF_INET);
1505 /* Do lookup on IPv4 system */
1508 addr.s_addr = (S_ADDR_TYPE)inet_addr(CS sender_host_address);
1509 hosts = gethostbyaddr(CS(&addr), sizeof(addr), AF_INET);
1512 if ( slow_lookup_log
1513 && (time_msec = get_time_in_ms() - time_msec) > slow_lookup_log
1515 log_long_lookup(US"name", sender_host_address, time_msec);
1517 /* Failed to look up the host. */
1521 HDEBUG(D_host_lookup) debug_printf("IP address lookup failed: h_errno=%d\n",
1523 return (h_errno == TRY_AGAIN || h_errno == NO_RECOVERY) ? DEFER : FAIL;
1526 /* It seems there are some records in the DNS that yield an empty name. We
1527 treat this as non-existent. In some operating systems, this is returned as an
1528 empty string; in others as a single dot. */
1530 if (hosts->h_name == NULL || hosts->h_name[0] == 0 || hosts->h_name[0] == '.')
1532 HDEBUG(D_host_lookup) debug_printf("IP address lookup yielded an empty name: "
1533 "treated as non-existent host name\n");
1537 /* Copy and lowercase the name, which is in static storage in many systems.
1538 Put it in permanent memory. */
1540 s = (uschar *)hosts->h_name;
1541 len = Ustrlen(s) + 1;
1542 t = sender_host_name = store_get_perm(len);
1543 while (*s != 0) *t++ = tolower(*s++);
1546 /* If the host has aliases, build a copy of the alias list */
1548 if (hosts->h_aliases != NULL)
1551 uschar **aliases, **ptr;
1552 for (aliases = USS hosts->h_aliases; *aliases != NULL; aliases++) count++;
1553 ptr = sender_host_aliases = store_get_perm(count * sizeof(uschar *));
1554 for (aliases = USS hosts->h_aliases; *aliases != NULL; aliases++)
1556 uschar *s = *aliases;
1557 int len = Ustrlen(s) + 1;
1558 uschar *t = *ptr++ = store_get_perm(len);
1559 while (*s != 0) *t++ = tolower(*s++);
1570 /*************************************************
1571 * Find host name for incoming call *
1572 *************************************************/
1574 /* Put the name in permanent store, pointed to by sender_host_name. We also set
1575 up a list of alias names, pointed to by sender_host_alias. The list is
1576 NULL-terminated. The incoming address is in sender_host_address, either in
1577 dotted-quad form for IPv4 or in colon-separated form for IPv6.
1579 This function does a thorough check that the names it finds point back to the
1580 incoming IP address. Any that do not are discarded. Note that this is relied on
1581 by the ACL reverse_host_lookup check.
1583 On some systems, get{host,ipnode}byaddr() appears to do this internally, but
1584 this it not universally true. Also, for release 4.30, this function was changed
1585 to do a direct DNS lookup first, by default[1], because it turns out that that
1586 is the only guaranteed way to find all the aliases on some systems. My
1587 experiments indicate that Solaris gethostbyaddr() gives the aliases for but
1590 [1] The actual order is controlled by the host_lookup_order option.
1593 Returns: OK on success, the answer being placed in the global variable
1594 sender_host_name, with any aliases in a list hung off
1596 FAIL if no host name can be found
1597 DEFER if a temporary error was encountered
1599 The variable host_lookup_msg is set to an empty string on sucess, or to a
1600 reason for the failure otherwise, in a form suitable for tagging onto an error
1601 message, and also host_lookup_failed is set TRUE if the lookup failed. If there
1602 was a defer, host_lookup_deferred is set TRUE.
1604 Any dynamically constructed string for host_lookup_msg must be in permanent
1605 store, because it might be used for several incoming messages on the same SMTP
1609 host_name_lookup(void)
1613 uschar *hname, *save_hostname;
1617 const uschar *list = host_lookup_order;
1622 sender_host_dnssec = host_lookup_deferred = host_lookup_failed = FALSE;
1624 HDEBUG(D_host_lookup)
1625 debug_printf("looking up host name for %s\n", sender_host_address);
1627 /* For testing the case when a lookup does not complete, we have a special
1628 reserved IP address. */
1630 if (running_in_test_harness &&
1631 Ustrcmp(sender_host_address, "99.99.99.99") == 0)
1633 HDEBUG(D_host_lookup)
1634 debug_printf("Test harness: host name lookup returns DEFER\n");
1635 host_lookup_deferred = TRUE;
1639 /* Do lookups directly in the DNS or via gethostbyaddr() (or equivalent), in
1640 the order specified by the host_lookup_order option. */
1642 while ((ordername = string_nextinlist(&list, &sep, buffer, sizeof(buffer)))
1645 if (strcmpic(ordername, US"bydns") == 0)
1647 dns_init(FALSE, FALSE, FALSE); /* dnssec ctrl by dns_dnssec_ok glbl */
1648 dns_build_reverse(sender_host_address, buffer);
1649 rc = dns_lookup_timerwrap(&dnsa, buffer, T_PTR, NULL);
1651 /* The first record we come across is used for the name; others are
1652 considered to be aliases. We have to scan twice, in order to find out the
1653 number of aliases. However, if all the names are empty, we will behave as
1654 if failure. (PTR records that yield empty names have been encountered in
1657 if (rc == DNS_SUCCEED)
1659 uschar **aptr = NULL;
1662 int old_pool = store_pool;
1664 /* Ideally we'd check DNSSEC both forward and reverse, but we use the
1665 gethost* routines for forward, so can't do that unless/until we rewrite. */
1666 sender_host_dnssec = dns_is_secure(&dnsa);
1668 debug_printf("Reverse DNS security status: %s\n",
1669 sender_host_dnssec ? "DNSSEC verified (AD)" : "unverified");
1671 store_pool = POOL_PERM; /* Save names in permanent storage */
1673 for (rr = dns_next_rr(&dnsa, &dnss, RESET_ANSWERS);
1675 rr = dns_next_rr(&dnsa, &dnss, RESET_NEXT))
1677 if (rr->type == T_PTR) count++;
1680 /* Get store for the list of aliases. For compatibility with
1681 gethostbyaddr, we make an empty list if there are none. */
1683 aptr = sender_host_aliases = store_get(count * sizeof(uschar *));
1685 /* Re-scan and extract the names */
1687 for (rr = dns_next_rr(&dnsa, &dnss, RESET_ANSWERS);
1689 rr = dns_next_rr(&dnsa, &dnss, RESET_NEXT))
1692 if (rr->type != T_PTR) continue;
1693 s = store_get(ssize);
1695 /* If an overlong response was received, the data will have been
1696 truncated and dn_expand may fail. */
1698 if (dn_expand(dnsa.answer, dnsa.answer + dnsa.answerlen,
1699 (uschar *)(rr->data), (DN_EXPAND_ARG4_TYPE)(s), ssize) < 0)
1701 log_write(0, LOG_MAIN, "host name alias list truncated for %s",
1702 sender_host_address);
1706 store_reset(s + Ustrlen(s) + 1);
1709 HDEBUG(D_host_lookup) debug_printf("IP address lookup yielded an "
1710 "empty name: treated as non-existent host name\n");
1713 if (sender_host_name == NULL) sender_host_name = s;
1715 while (*s != 0) { *s = tolower(*s); s++; }
1718 *aptr = NULL; /* End of alias list */
1719 store_pool = old_pool; /* Reset store pool */
1721 /* If we've found a names, break out of the "order" loop */
1723 if (sender_host_name != NULL) break;
1726 /* If the DNS lookup deferred, we must also defer. */
1728 if (rc == DNS_AGAIN)
1730 HDEBUG(D_host_lookup)
1731 debug_printf("IP address PTR lookup gave temporary error\n");
1732 host_lookup_deferred = TRUE;
1737 /* Do a lookup using gethostbyaddr() - or equivalent */
1739 else if (strcmpic(ordername, US"byaddr") == 0)
1741 HDEBUG(D_host_lookup)
1742 debug_printf("IP address lookup using gethostbyaddr()\n");
1743 rc = host_name_lookup_byaddr();
1746 host_lookup_deferred = TRUE;
1747 return rc; /* Can't carry on */
1749 if (rc == OK) break; /* Found a name */
1751 } /* Loop for bydns/byaddr scanning */
1753 /* If we have failed to find a name, return FAIL and log when required.
1754 NB host_lookup_msg must be in permanent store. */
1756 if (sender_host_name == NULL)
1758 if (host_checking || !log_testing_mode)
1759 log_write(L_host_lookup_failed, LOG_MAIN, "no host name found for IP "
1760 "address %s", sender_host_address);
1761 host_lookup_msg = US" (failed to find host name from IP address)";
1762 host_lookup_failed = TRUE;
1766 HDEBUG(D_host_lookup)
1768 uschar **aliases = sender_host_aliases;
1769 debug_printf("IP address lookup yielded \"%s\"\n", sender_host_name);
1770 while (*aliases != NULL) debug_printf(" alias \"%s\"\n", *aliases++);
1773 /* We need to verify that a forward lookup on the name we found does indeed
1774 correspond to the address. This is for security: in principle a malefactor who
1775 happened to own a reverse zone could set it to point to any names at all.
1777 This code was present in versions of Exim before 3.20. At that point I took it
1778 out because I thought that gethostbyaddr() did the check anyway. It turns out
1779 that this isn't always the case, so it's coming back in at 4.01. This version
1780 is actually better, because it also checks aliases.
1782 The code was made more robust at release 4.21. Prior to that, it accepted all
1783 the names if any of them had the correct IP address. Now the code checks all
1784 the names, and accepts only those that have the correct IP address. */
1786 save_hostname = sender_host_name; /* Save for error messages */
1787 aliases = sender_host_aliases;
1788 for (hname = sender_host_name; hname != NULL; hname = *aliases++)
1798 /* When called with the last argument FALSE, host_find_byname() won't return
1799 HOST_FOUND_LOCAL. If the incoming address is an IPv4 address expressed in
1800 IPv6 format, we must compare the IPv4 part to any IPv4 addresses. */
1802 if ((rc = host_find_byname(&h, NULL, 0, NULL, FALSE)) == HOST_FOUND)
1805 HDEBUG(D_host_lookup) debug_printf("checking addresses for %s\n", hname);
1806 for (hh = &h; hh != NULL; hh = hh->next)
1808 if (host_is_in_net(hh->address, sender_host_address, 0))
1810 HDEBUG(D_host_lookup) debug_printf(" %s OK\n", hh->address);
1816 HDEBUG(D_host_lookup) debug_printf(" %s\n", hh->address);
1819 if (!ok) HDEBUG(D_host_lookup)
1820 debug_printf("no IP address for %s matched %s\n", hname,
1821 sender_host_address);
1823 else if (rc == HOST_FIND_AGAIN)
1825 HDEBUG(D_host_lookup) debug_printf("temporary error for host name lookup\n");
1826 host_lookup_deferred = TRUE;
1827 sender_host_name = NULL;
1832 HDEBUG(D_host_lookup) debug_printf("no IP addresses found for %s\n", hname);
1835 /* If this name is no good, and it's the sender name, set it null pro tem;
1836 if it's an alias, just remove it from the list. */
1840 if (hname == sender_host_name) sender_host_name = NULL; else
1842 uschar **a; /* Don't amalgamate - some */
1843 a = --aliases; /* compilers grumble */
1844 while (*a != NULL) { *a = a[1]; a++; }
1849 /* If sender_host_name == NULL, it means we didn't like the name. Replace
1850 it with the first alias, if there is one. */
1852 if (sender_host_name == NULL && *sender_host_aliases != NULL)
1853 sender_host_name = *sender_host_aliases++;
1855 /* If we now have a main name, all is well. */
1857 if (sender_host_name != NULL) return OK;
1859 /* We have failed to find an address that matches. */
1861 HDEBUG(D_host_lookup)
1862 debug_printf("%s does not match any IP address for %s\n",
1863 sender_host_address, save_hostname);
1865 /* This message must be in permanent store */
1867 old_pool = store_pool;
1868 store_pool = POOL_PERM;
1869 host_lookup_msg = string_sprintf(" (%s does not match any IP address for %s)",
1870 sender_host_address, save_hostname);
1871 store_pool = old_pool;
1872 host_lookup_failed = TRUE;
1879 /*************************************************
1880 * Find IP address(es) for host by name *
1881 *************************************************/
1883 /* The input is a host_item structure with the name filled in and the address
1884 field set to NULL. We use gethostbyname() or getipnodebyname() or
1885 gethostbyname2(), as appropriate. Of course, these functions may use the DNS,
1886 but they do not do MX processing. It appears, however, that in some systems the
1887 current setting of resolver options is used when one of these functions calls
1888 the resolver. For this reason, we call dns_init() at the start, with arguments
1889 influenced by bits in "flags", just as we do for host_find_bydns().
1891 The second argument provides a host list (usually an IP list) of hosts to
1892 ignore. This makes it possible to ignore IPv6 link-local addresses or loopback
1893 addresses in unreasonable places.
1895 The lookup may result in a change of name. For compatibility with the dns
1896 lookup, return this via fully_qualified_name as well as updating the host item.
1897 The lookup may also yield more than one IP address, in which case chain on
1898 subsequent host_item structures.
1901 host a host item with the name and MX filled in;
1902 the address is to be filled in;
1903 multiple IP addresses cause other host items to be
1905 ignore_target_hosts a list of hosts to ignore
1906 flags HOST_FIND_QUALIFY_SINGLE ) passed to
1907 HOST_FIND_SEARCH_PARENTS ) dns_init()
1908 fully_qualified_name if not NULL, set to point to host name for
1909 compatibility with host_find_bydns
1910 local_host_check TRUE if a check for the local host is wanted
1912 Returns: HOST_FIND_FAILED Failed to find the host or domain
1913 HOST_FIND_AGAIN Try again later
1914 HOST_FOUND Host found - data filled in
1915 HOST_FOUND_LOCAL Host found and is the local host
1919 host_find_byname(host_item *host, const uschar *ignore_target_hosts, int flags,
1920 const uschar **fully_qualified_name, BOOL local_host_check)
1922 int i, yield, times;
1924 host_item *last = NULL;
1925 BOOL temp_error = FALSE;
1930 /* If we are in the test harness, a name ending in .test.again.dns always
1931 forces a temporary error response, unless the name is in
1932 dns_again_means_nonexist. */
1934 if (running_in_test_harness)
1936 const uschar *endname = host->name + Ustrlen(host->name);
1937 if (Ustrcmp(endname - 14, "test.again.dns") == 0) goto RETURN_AGAIN;
1940 /* Make sure DNS options are set as required. This appears to be necessary in
1941 some circumstances when the get..byname() function actually calls the DNS. */
1943 dns_init((flags & HOST_FIND_QUALIFY_SINGLE) != 0,
1944 (flags & HOST_FIND_SEARCH_PARENTS) != 0,
1945 FALSE); /*XXX dnssec? */
1947 /* In an IPv6 world, unless IPv6 has been disabled, we need to scan for both
1948 kinds of address, so go round the loop twice. Note that we have ensured that
1949 AF_INET6 is defined even in an IPv4 world, which makes for slightly tidier
1950 code. However, if dns_ipv4_lookup matches the domain, we also just do IPv4
1951 lookups here (except when testing standalone). */
1958 (dns_ipv4_lookup != NULL &&
1959 match_isinlist(host->name, CUSS &dns_ipv4_lookup, 0, NULL, NULL,
1960 MCL_DOMAIN, TRUE, NULL) == OK))
1963 { af = AF_INET; times = 1; }
1965 { af = AF_INET6; times = 2; }
1967 /* No IPv6 support */
1969 #else /* HAVE_IPV6 */
1971 #endif /* HAVE_IPV6 */
1973 /* Initialize the flag that gets set for DNS syntax check errors, so that the
1974 interface to this function can be similar to host_find_bydns. */
1976 host_find_failed_syntax = FALSE;
1978 /* Loop to look up both kinds of address in an IPv6 world */
1980 for (i = 1; i <= times;
1982 af = AF_INET, /* If 2 passes, IPv4 on the second */
1988 struct hostent *hostdata;
1989 unsigned long time_msec;
1992 printf("Looking up: %s\n", host->name);
1995 if (slow_lookup_log) time_msec = get_time_in_ms();
1998 if (running_in_test_harness)
1999 hostdata = host_fake_gethostbyname(host->name, af, &error_num);
2002 #if HAVE_GETIPNODEBYNAME
2003 hostdata = getipnodebyname(CS host->name, af, 0, &error_num);
2005 hostdata = gethostbyname2(CS host->name, af);
2006 error_num = h_errno;
2010 #else /* not HAVE_IPV6 */
2011 if (running_in_test_harness)
2012 hostdata = host_fake_gethostbyname(host->name, AF_INET, &error_num);
2015 hostdata = gethostbyname(CS host->name);
2016 error_num = h_errno;
2018 #endif /* HAVE_IPV6 */
2021 && (time_msec = get_time_in_ms() - time_msec) > slow_lookup_log)
2022 log_long_lookup(US"name", host->name, time_msec);
2024 if (hostdata == NULL)
2029 case HOST_NOT_FOUND: error = US"HOST_NOT_FOUND"; break;
2030 case TRY_AGAIN: error = US"TRY_AGAIN"; break;
2031 case NO_RECOVERY: error = US"NO_RECOVERY"; break;
2032 case NO_DATA: error = US"NO_DATA"; break;
2033 #if NO_DATA != NO_ADDRESS
2034 case NO_ADDRESS: error = US"NO_ADDRESS"; break;
2036 default: error = US"?"; break;
2039 DEBUG(D_host_lookup) debug_printf("%s returned %d (%s)\n",
2041 #if HAVE_GETIPNODEBYNAME
2042 (af == AF_INET6)? "getipnodebyname(af=inet6)" : "getipnodebyname(af=inet)",
2044 (af == AF_INET6)? "gethostbyname2(af=inet6)" : "gethostbyname2(af=inet)",
2051 if (error_num == TRY_AGAIN || error_num == NO_RECOVERY) temp_error = TRUE;
2054 if ((hostdata->h_addr_list)[0] == NULL) continue;
2056 /* Replace the name with the fully qualified one if necessary, and fill in
2057 the fully_qualified_name pointer. */
2059 if (hostdata->h_name[0] != 0 &&
2060 Ustrcmp(host->name, hostdata->h_name) != 0)
2061 host->name = string_copy_dnsdomain((uschar *)hostdata->h_name);
2062 if (fully_qualified_name != NULL) *fully_qualified_name = host->name;
2064 /* Get the list of addresses. IPv4 and IPv6 addresses can be distinguished
2065 by their different lengths. Scan the list, ignoring any that are to be
2066 ignored, and build a chain from the rest. */
2068 ipv4_addr = hostdata->h_length == sizeof(struct in_addr);
2070 for (addrlist = USS hostdata->h_addr_list; *addrlist != NULL; addrlist++)
2072 uschar *text_address =
2073 host_ntoa(ipv4_addr? AF_INET:AF_INET6, *addrlist, NULL, NULL);
2076 if (ignore_target_hosts != NULL &&
2077 verify_check_this_host(&ignore_target_hosts, NULL, host->name,
2078 text_address, NULL) == OK)
2080 DEBUG(D_host_lookup)
2081 debug_printf("ignored host %s [%s]\n", host->name, text_address);
2086 /* If this is the first address, last == NULL and we put the data in the
2091 host->address = text_address;
2092 host->port = PORT_NONE;
2093 host->status = hstatus_unknown;
2094 host->why = hwhy_unknown;
2095 host->dnssec = DS_UNK;
2099 /* Else add further host item blocks for any other addresses, keeping
2104 host_item *next = store_get(sizeof(host_item));
2105 next->name = host->name;
2106 next->mx = host->mx;
2107 next->address = text_address;
2108 next->port = PORT_NONE;
2109 next->status = hstatus_unknown;
2110 next->why = hwhy_unknown;
2111 next->dnssec = DS_UNK;
2113 next->next = last->next;
2120 /* If no hosts were found, the address field in the original host block will be
2121 NULL. If temp_error is set, at least one of the lookups gave a temporary error,
2122 so we pass that back. */
2124 if (host->address == NULL)
2128 (message_id[0] == 0 && smtp_in != NULL)?
2129 string_sprintf("no IP address found for host %s (during %s)", host->name,
2130 smtp_get_connection_info()) :
2132 string_sprintf("no IP address found for host %s", host->name);
2134 HDEBUG(D_host_lookup) debug_printf("%s\n", msg);
2135 if (temp_error) goto RETURN_AGAIN;
2136 if (host_checking || !log_testing_mode)
2137 log_write(L_host_lookup_failed, LOG_MAIN, "%s", msg);
2138 return HOST_FIND_FAILED;
2141 /* Remove any duplicate IP addresses, then check to see if this is the local
2142 host if required. */
2144 host_remove_duplicates(host, &last);
2145 yield = local_host_check?
2146 host_scan_for_local_hosts(host, &last, NULL) : HOST_FOUND;
2148 HDEBUG(D_host_lookup)
2151 if (fully_qualified_name != NULL)
2152 debug_printf("fully qualified name = %s\n", *fully_qualified_name);
2153 debug_printf("%s looked up these IP addresses:\n",
2155 #if HAVE_GETIPNODEBYNAME
2164 for (h = host; h != last->next; h = h->next)
2165 debug_printf(" name=%s address=%s\n", h->name,
2166 (h->address == NULL)? US"<null>" : h->address);
2169 /* Return the found status. */
2173 /* Handle the case when there is a temporary error. If the name matches
2174 dns_again_means_nonexist, return permanent rather than temporary failure. */
2180 const uschar *save = deliver_domain;
2181 deliver_domain = host->name; /* set $domain */
2182 rc = match_isinlist(host->name, CUSS &dns_again_means_nonexist, 0, NULL, NULL,
2183 MCL_DOMAIN, TRUE, NULL);
2184 deliver_domain = save;
2187 DEBUG(D_host_lookup) debug_printf("%s is in dns_again_means_nonexist: "
2188 "returning HOST_FIND_FAILED\n", host->name);
2189 return HOST_FIND_FAILED;
2192 return HOST_FIND_AGAIN;
2198 /*************************************************
2199 * Fill in a host address from the DNS *
2200 *************************************************/
2202 /* Given a host item, with its name, port and mx fields set, and its address
2203 field set to NULL, fill in its IP address from the DNS. If it is multi-homed,
2204 create additional host items for the additional addresses, copying all the
2205 other fields, and randomizing the order.
2207 On IPv6 systems, A6 records are sought first (but only if support for A6 is
2208 configured - they may never become mainstream), then AAAA records are sought,
2209 and finally A records are sought as well.
2211 The host name may be changed if the DNS returns a different name - e.g. fully
2212 qualified or changed via CNAME. If fully_qualified_name is not NULL, dns_lookup
2213 ensures that it points to the fully qualified name. However, this is the fully
2214 qualified version of the original name; if a CNAME is involved, the actual
2215 canonical host name may be different again, and so we get it directly from the
2216 relevant RR. Note that we do NOT change the mx field of the host item in this
2217 function as it may be called to set the addresses of hosts taken from MX
2221 host points to the host item we're filling in
2222 lastptr points to pointer to last host item in a chain of
2223 host items (may be updated if host is last and gets
2224 extended because multihomed)
2225 ignore_target_hosts list of hosts to ignore
2226 allow_ip if TRUE, recognize an IP address and return it
2227 fully_qualified_name if not NULL, return fully qualified name here if
2228 the contents are different (i.e. it must be preset
2230 dnnssec_require if TRUE check the DNS result AD bit
2232 Returns: HOST_FIND_FAILED couldn't find A record
2233 HOST_FIND_AGAIN try again later
2234 HOST_FOUND found AAAA and/or A record(s)
2235 HOST_IGNORED found, but all IPs ignored
2239 set_address_from_dns(host_item *host, host_item **lastptr,
2240 const uschar *ignore_target_hosts, BOOL allow_ip,
2241 const uschar **fully_qualified_name,
2242 BOOL dnssec_request, BOOL dnssec_require)
2245 host_item *thishostlast = NULL; /* Indicates not yet filled in anything */
2246 BOOL v6_find_again = FALSE;
2249 /* If allow_ip is set, a name which is an IP address returns that value
2250 as its address. This is used for MX records when allow_mx_to_ip is set, for
2251 those sites that feel they have to flaunt the RFC rules. */
2253 if (allow_ip && string_is_ip_address(host->name, NULL) != 0)
2256 if (ignore_target_hosts != NULL &&
2257 verify_check_this_host(&ignore_target_hosts, NULL, host->name,
2258 host->name, NULL) == OK)
2259 return HOST_IGNORED;
2262 host->address = host->name;
2266 /* On an IPv6 system, unless IPv6 is disabled, go round the loop up to three
2267 times, looking for A6 and AAAA records the first two times. However, unless
2268 doing standalone testing, we force an IPv4 lookup if the domain matches
2269 dns_ipv4_lookup is set. Since A6 records look like being abandoned, support
2270 them only if explicitly configured to do so. On an IPv4 system, go round the
2271 loop once only, looking only for A records. */
2275 if (disable_ipv6 || (dns_ipv4_lookup != NULL &&
2276 match_isinlist(host->name, CUSS &dns_ipv4_lookup, 0, NULL, NULL,
2277 MCL_DOMAIN, TRUE, NULL) == OK))
2278 i = 0; /* look up A records only */
2280 #endif /* STAND_ALONE */
2282 i = 1; /* look up AAAA and A records */
2284 /* The IPv4 world */
2286 #else /* HAVE_IPV6 */
2287 i = 0; /* look up A records only */
2288 #endif /* HAVE_IPV6 */
2292 static int types[] = { T_A, T_AAAA, T_A6 };
2293 int type = types[i];
2294 int randoffset = (i == 0)? 500 : 0; /* Ensures v6 sorts before v4 */
2298 int rc = dns_lookup_timerwrap(&dnsa, host->name, type, fully_qualified_name);
2299 lookup_dnssec_authenticated = !dnssec_request ? NULL
2300 : dns_is_secure(&dnsa) ? US"yes" : US"no";
2302 /* We want to return HOST_FIND_AGAIN if one of the A, A6, or AAAA lookups
2303 fails or times out, but not if another one succeeds. (In the early
2304 IPv6 days there are name servers that always fail on AAAA, but are happy
2305 to give out an A record. We want to proceed with that A record.) */
2307 if (rc != DNS_SUCCEED)
2309 if (i == 0) /* Just tried for an A record, i.e. end of loop */
2311 if (host->address != NULL) return HOST_FOUND; /* A6 or AAAA was found */
2312 if (rc == DNS_AGAIN || rc == DNS_FAIL || v6_find_again)
2313 return HOST_FIND_AGAIN;
2314 return HOST_FIND_FAILED; /* DNS_NOMATCH or DNS_NODATA */
2317 /* Tried for an A6 or AAAA record: remember if this was a temporary
2318 error, and look for the next record type. */
2320 if (rc != DNS_NOMATCH && rc != DNS_NODATA) v6_find_again = TRUE;
2326 if (dns_is_secure(&dnsa))
2328 DEBUG(D_host_lookup) debug_printf("%s A DNSSEC\n", host->name);
2329 if (host->dnssec == DS_UNK) /* set in host_find_bydns() */
2330 host->dnssec = DS_YES;
2336 log_write(L_host_lookup_failed, LOG_MAIN,
2337 "dnssec fail on %s for %.256s",
2338 i>1 ? "A6" : i>0 ? "AAAA" : "A", host->name);
2341 if (host->dnssec == DS_YES) /* set in host_find_bydns() */
2343 DEBUG(D_host_lookup) debug_printf("%s A cancel DNSSEC\n", host->name);
2344 host->dnssec = DS_NO;
2345 lookup_dnssec_authenticated = US"no";
2350 /* Lookup succeeded: fill in the given host item with the first non-ignored
2351 address found; create additional items for any others. A single A6 record
2352 may generate more than one address. The lookup had a chance to update the
2353 fqdn; we do not want any later times round the loop to do so. */
2355 fully_qualified_name = NULL;
2357 for (rr = dns_next_rr(&dnsa, &dnss, RESET_ANSWERS);
2359 rr = dns_next_rr(&dnsa, &dnss, RESET_NEXT))
2361 if (rr->type == type)
2363 /* dns_address *da = dns_address_from_rr(&dnsa, rr); */
2366 da = dns_address_from_rr(&dnsa, rr);
2368 DEBUG(D_host_lookup)
2370 if (!da) debug_printf("no addresses extracted from A6 RR for %s\n",
2374 /* This loop runs only once for A and AAAA records, but may run
2375 several times for an A6 record that generated multiple addresses. */
2377 for (; da; da = da->next)
2380 if (ignore_target_hosts != NULL &&
2381 verify_check_this_host(&ignore_target_hosts, NULL,
2382 host->name, da->address, NULL) == OK)
2384 DEBUG(D_host_lookup)
2385 debug_printf("ignored host %s [%s]\n", host->name, da->address);
2390 /* If this is the first address, stick it in the given host block,
2391 and change the name if the returned RR has a different name. */
2393 if (thishostlast == NULL)
2395 if (strcmpic(host->name, rr->name) != 0)
2396 host->name = string_copy_dnsdomain(rr->name);
2397 host->address = da->address;
2398 host->sort_key = host->mx * 1000 + random_number(500) + randoffset;
2399 host->status = hstatus_unknown;
2400 host->why = hwhy_unknown;
2401 thishostlast = host;
2404 /* Not the first address. Check for, and ignore, duplicates. Then
2405 insert in the chain at a random point. */
2412 /* End of our local chain is specified by "thishostlast". */
2414 for (next = host;; next = next->next)
2416 if (Ustrcmp(CS da->address, next->address) == 0) break;
2417 if (next == thishostlast) { next = NULL; break; }
2419 if (next != NULL) continue; /* With loop for next address */
2421 /* Not a duplicate */
2423 new_sort_key = host->mx * 1000 + random_number(500) + randoffset;
2424 next = store_get(sizeof(host_item));
2426 /* New address goes first: insert the new block after the first one
2427 (so as not to disturb the original pointer) but put the new address
2428 in the original block. */
2430 if (new_sort_key < host->sort_key)
2432 *next = *host; /* Copies port */
2434 host->address = da->address;
2435 host->sort_key = new_sort_key;
2436 if (thishostlast == host) thishostlast = next; /* Local last */
2437 if (*lastptr == host) *lastptr = next; /* Global last */
2440 /* Otherwise scan down the addresses for this host to find the
2441 one to insert after. */
2445 host_item *h = host;
2446 while (h != thishostlast)
2448 if (new_sort_key < h->next->sort_key) break;
2451 *next = *h; /* Copies port */
2453 next->address = da->address;
2454 next->sort_key = new_sort_key;
2455 if (h == thishostlast) thishostlast = next; /* Local last */
2456 if (h == *lastptr) *lastptr = next; /* Global last */
2464 /* Control gets here only if the third lookup (the A record) succeeded.
2465 However, the address may not be filled in if it was ignored. */
2467 return (host->address == NULL)? HOST_IGNORED : HOST_FOUND;
2473 /*************************************************
2474 * Find IP addresses and host names via DNS *
2475 *************************************************/
2477 /* The input is a host_item structure with the name field filled in and the
2478 address field set to NULL. This may be in a chain of other host items. The
2479 lookup may result in more than one IP address, in which case we must created
2480 new host blocks for the additional addresses, and insert them into the chain.
2481 The original name may not be fully qualified. Use the fully_qualified_name
2482 argument to return the official name, as returned by the resolver.
2485 host point to initial host item
2486 ignore_target_hosts a list of hosts to ignore
2487 whichrrs flags indicating which RRs to look for:
2488 HOST_FIND_BY_SRV => look for SRV
2489 HOST_FIND_BY_MX => look for MX
2490 HOST_FIND_BY_A => look for A or AAAA
2491 also flags indicating how the lookup is done
2492 HOST_FIND_QUALIFY_SINGLE ) passed to the
2493 HOST_FIND_SEARCH_PARENTS ) resolver
2494 srv_service when SRV used, the service name
2495 srv_fail_domains DNS errors for these domains => assume nonexist
2496 mx_fail_domains DNS errors for these domains => assume nonexist
2497 dnssec_request_domains => make dnssec request
2498 dnssec_require_domains => ditto and nonexist failures
2499 fully_qualified_name if not NULL, return fully-qualified name
2500 removed set TRUE if local host was removed from the list
2502 Returns: HOST_FIND_FAILED Failed to find the host or domain;
2503 if there was a syntax error,
2504 host_find_failed_syntax is set.
2505 HOST_FIND_AGAIN Could not resolve at this time
2506 HOST_FOUND Host found
2507 HOST_FOUND_LOCAL The lowest MX record points to this
2508 machine, if MX records were found, or
2509 an A record that was found contains
2510 an address of the local host
2514 host_find_bydns(host_item *host, const uschar *ignore_target_hosts, int whichrrs,
2515 uschar *srv_service, uschar *srv_fail_domains, uschar *mx_fail_domains,
2516 uschar *dnssec_request_domains, uschar *dnssec_require_domains,
2517 const uschar **fully_qualified_name, BOOL *removed)
2519 host_item *h, *last;
2526 BOOL dnssec_require = match_isinlist(host->name, CUSS &dnssec_require_domains,
2527 0, NULL, NULL, MCL_DOMAIN, TRUE, NULL) == OK;
2528 BOOL dnssec_request = dnssec_require
2529 || match_isinlist(host->name, CUSS &dnssec_request_domains,
2530 0, NULL, NULL, MCL_DOMAIN, TRUE, NULL) == OK;
2531 dnssec_status_t dnssec;
2533 /* Set the default fully qualified name to the incoming name, initialize the
2534 resolver if necessary, set up the relevant options, and initialize the flag
2535 that gets set for DNS syntax check errors. */
2537 if (fully_qualified_name != NULL) *fully_qualified_name = host->name;
2538 dns_init((whichrrs & HOST_FIND_QUALIFY_SINGLE) != 0,
2539 (whichrrs & HOST_FIND_SEARCH_PARENTS) != 0,
2542 host_find_failed_syntax = FALSE;
2544 /* First, if requested, look for SRV records. The service name is given; we
2545 assume TCP progocol. DNS domain names are constrained to a maximum of 256
2546 characters, so the code below should be safe. */
2548 if ((whichrrs & HOST_FIND_BY_SRV) != 0)
2551 uschar *temp_fully_qualified_name = buffer;
2554 (void)sprintf(CS buffer, "_%s._tcp.%n%.256s", srv_service, &prefix_length,
2558 /* Search for SRV records. If the fully qualified name is different to
2559 the input name, pass back the new original domain, without the prepended
2563 lookup_dnssec_authenticated = NULL;
2564 rc = dns_lookup_timerwrap(&dnsa, buffer, ind_type, CUSS &temp_fully_qualified_name);
2568 if (dns_is_secure(&dnsa))
2569 { dnssec = DS_YES; lookup_dnssec_authenticated = US"yes"; }
2571 { dnssec = DS_NO; lookup_dnssec_authenticated = US"no"; }
2574 if (temp_fully_qualified_name != buffer && fully_qualified_name != NULL)
2575 *fully_qualified_name = temp_fully_qualified_name + prefix_length;
2577 /* On DNS failures, we give the "try again" error unless the domain is
2578 listed as one for which we continue. */
2580 if (rc == DNS_SUCCEED && dnssec_require && !dns_is_secure(&dnsa))
2582 log_write(L_host_lookup_failed, LOG_MAIN,
2583 "dnssec fail on SRV for %.256s", host->name);
2586 if (rc == DNS_FAIL || rc == DNS_AGAIN)
2589 if (match_isinlist(host->name, CUSS &srv_fail_domains, 0, NULL, NULL,
2590 MCL_DOMAIN, TRUE, NULL) != OK)
2592 { yield = HOST_FIND_AGAIN; goto out; }
2593 DEBUG(D_host_lookup) debug_printf("DNS_%s treated as DNS_NODATA "
2594 "(domain in srv_fail_domains)\n", (rc == DNS_FAIL)? "FAIL":"AGAIN");
2598 /* If we did not find any SRV records, search the DNS for MX records, if
2599 requested to do so. If the result is DNS_NOMATCH, it means there is no such
2600 domain, and there's no point in going on to look for address records with the
2601 same domain. The result will be DNS_NODATA if the domain exists but has no MX
2602 records. On DNS failures, we give the "try again" error unless the domain is
2603 listed as one for which we continue. */
2605 if (rc != DNS_SUCCEED && (whichrrs & HOST_FIND_BY_MX) != 0)
2609 lookup_dnssec_authenticated = NULL;
2610 rc = dns_lookup_timerwrap(&dnsa, host->name, ind_type, fully_qualified_name);
2614 if (dns_is_secure(&dnsa))
2616 DEBUG(D_host_lookup) debug_printf("%s MX DNSSEC\n", host->name);
2617 dnssec = DS_YES; lookup_dnssec_authenticated = US"yes";
2621 dnssec = DS_NO; lookup_dnssec_authenticated = US"no";
2628 yield = HOST_FIND_FAILED; goto out;
2631 if (!dnssec_require || dns_is_secure(&dnsa))
2633 log_write(L_host_lookup_failed, LOG_MAIN,
2634 "dnssec fail on MX for %.256s", host->name);
2641 if (match_isinlist(host->name, CUSS &mx_fail_domains, 0, NULL, NULL,
2642 MCL_DOMAIN, TRUE, NULL) != OK)
2644 { yield = HOST_FIND_AGAIN; goto out; }
2645 DEBUG(D_host_lookup) debug_printf("DNS_%s treated as DNS_NODATA "
2646 "(domain in mx_fail_domains)\n", (rc == DNS_FAIL)? "FAIL":"AGAIN");
2651 /* If we haven't found anything yet, and we are requested to do so, try for an
2652 A or AAAA record. If we find it (or them) check to see that it isn't the local
2655 if (rc != DNS_SUCCEED)
2657 if ((whichrrs & HOST_FIND_BY_A) == 0)
2659 DEBUG(D_host_lookup) debug_printf("Address records are not being sought\n");
2660 yield = HOST_FIND_FAILED;
2664 last = host; /* End of local chainlet */
2666 host->port = PORT_NONE;
2667 host->dnssec = DS_UNK;
2668 lookup_dnssec_authenticated = NULL;
2669 rc = set_address_from_dns(host, &last, ignore_target_hosts, FALSE,
2670 fully_qualified_name, dnssec_request, dnssec_require);
2672 /* If one or more address records have been found, check that none of them
2673 are local. Since we know the host items all have their IP addresses
2674 inserted, host_scan_for_local_hosts() can only return HOST_FOUND or
2675 HOST_FOUND_LOCAL. We do not need to scan for duplicate IP addresses here,
2676 because set_address_from_dns() removes them. */
2678 if (rc == HOST_FOUND)
2679 rc = host_scan_for_local_hosts(host, &last, removed);
2681 if (rc == HOST_IGNORED) rc = HOST_FIND_FAILED; /* No special action */
2683 DEBUG(D_host_lookup)
2686 if (host->address != NULL)
2688 if (fully_qualified_name != NULL)
2689 debug_printf("fully qualified name = %s\n", *fully_qualified_name);
2690 for (h = host; h != last->next; h = h->next)
2691 debug_printf("%s %s mx=%d sort=%d %s\n", h->name,
2692 (h->address == NULL)? US"<null>" : h->address, h->mx, h->sort_key,
2693 (h->status >= hstatus_unusable)? US"*" : US"");
2701 /* We have found one or more MX or SRV records. Sort them according to
2702 precedence. Put the data for the first one into the existing host block, and
2703 insert new host_item blocks into the chain for the remainder. For equal
2704 precedences one is supposed to randomize the order. To make this happen, the
2705 sorting is actually done on the MX value * 1000 + a random number. This is put
2706 into a host field called sort_key.
2708 In the case of hosts with both IPv6 and IPv4 addresses, we want to choose the
2709 IPv6 address in preference. At this stage, we don't know what kind of address
2710 the host has. We choose a random number < 500; if later we find an A record
2711 first, we add 500 to the random number. Then for any other address records, we
2712 use random numbers in the range 0-499 for AAAA records and 500-999 for A
2715 At this point we remove any duplicates that point to the same host, retaining
2716 only the one with the lowest precedence. We cannot yet check for precedence
2717 greater than that of the local host, because that test cannot be properly done
2718 until the addresses have been found - an MX record may point to a name for this
2719 host which is not the primary hostname. */
2721 last = NULL; /* Indicates that not even the first item is filled yet */
2723 for (rr = dns_next_rr(&dnsa, &dnss, RESET_ANSWERS);
2725 rr = dns_next_rr(&dnsa, &dnss, RESET_NEXT))
2728 int weight = 0; /* For SRV records */
2729 int port = PORT_NONE;
2730 uschar *s; /* MUST be unsigned for GETSHORT */
2733 if (rr->type != ind_type) continue;
2735 GETSHORT(precedence, s); /* Pointer s is advanced */
2737 /* For MX records, we use a random "weight" which causes multiple records of
2738 the same precedence to sort randomly. */
2740 if (ind_type == T_MX)
2741 weight = random_number(500);
2743 /* SRV records are specified with a port and a weight. The weight is used
2744 in a special algorithm. However, to start with, we just use it to order the
2745 records of equal priority (precedence). */
2749 GETSHORT(weight, s);
2753 /* Get the name of the host pointed to. */
2755 (void)dn_expand(dnsa.answer, dnsa.answer + dnsa.answerlen, s,
2756 (DN_EXPAND_ARG4_TYPE)data, sizeof(data));
2758 /* Check that we haven't already got this host on the chain; if we have,
2759 keep only the lower precedence. This situation shouldn't occur, but you
2760 never know what junk might get into the DNS (and this case has been seen on
2761 more than one occasion). */
2763 if (last != NULL) /* This is not the first record */
2765 host_item *prev = NULL;
2767 for (h = host; h != last->next; prev = h, h = h->next)
2769 if (strcmpic(h->name, data) == 0)
2771 DEBUG(D_host_lookup)
2772 debug_printf("discarded duplicate host %s (MX=%d)\n", data,
2773 (precedence > h->mx)? precedence : h->mx);
2774 if (precedence >= h->mx) goto NEXT_MX_RR; /* Skip greater precedence */
2775 if (h == host) /* Override first item */
2778 host->sort_key = precedence * 1000 + weight;
2782 /* Unwanted host item is not the first in the chain, so we can get
2783 get rid of it by cutting it out. */
2785 prev->next = h->next;
2786 if (h == last) last = prev;
2792 /* If this is the first MX or SRV record, put the data into the existing host
2793 block. Otherwise, add a new block in the correct place; if it has to be
2794 before the first block, copy the first block's data to a new second block. */
2798 host->name = string_copy_dnsdomain(data);
2799 host->address = NULL;
2801 host->mx = precedence;
2802 host->sort_key = precedence * 1000 + weight;
2803 host->status = hstatus_unknown;
2804 host->why = hwhy_unknown;
2805 host->dnssec = dnssec;
2809 /* Make a new host item and seek the correct insertion place */
2813 int sort_key = precedence * 1000 + weight;
2814 host_item *next = store_get(sizeof(host_item));
2815 next->name = string_copy_dnsdomain(data);
2816 next->address = NULL;
2818 next->mx = precedence;
2819 next->sort_key = sort_key;
2820 next->status = hstatus_unknown;
2821 next->why = hwhy_unknown;
2822 next->dnssec = dnssec;
2825 /* Handle the case when we have to insert before the first item. */
2827 if (sort_key < host->sort_key)
2834 if (last == host) last = next;
2837 /* Else scan down the items we have inserted as part of this exercise;
2838 don't go further. */
2842 for (h = host; h != last; h = h->next)
2844 if (sort_key < h->next->sort_key)
2846 next->next = h->next;
2852 /* Join on after the last host item that's part of this
2853 processing if we haven't stopped sooner. */
2857 next->next = last->next;
2864 NEXT_MX_RR: continue;
2867 /* If the list of hosts was obtained from SRV records, there are two things to
2868 do. First, if there is only one host, and it's name is ".", it means there is
2869 no SMTP service at this domain. Otherwise, we have to sort the hosts of equal
2870 priority according to their weights, using an algorithm that is defined in RFC
2871 2782. The hosts are currently sorted by priority and weight. For each priority
2872 group we have to pick off one host and put it first, and then repeat for any
2873 remaining in the same priority group. */
2875 if (ind_type == T_SRV)
2879 if (host == last && host->name[0] == 0)
2881 DEBUG(D_host_lookup) debug_printf("the single SRV record is \".\"\n");
2882 yield = HOST_FIND_FAILED;
2886 DEBUG(D_host_lookup)
2888 debug_printf("original ordering of hosts from SRV records:\n");
2889 for (h = host; h != last->next; h = h->next)
2890 debug_printf(" %s P=%d W=%d\n", h->name, h->mx, h->sort_key % 1000);
2893 for (pptr = &host, h = host; h != last; pptr = &(h->next), h = h->next)
2898 /* Find the last following host that has the same precedence. At the same
2899 time, compute the sum of the weights and the running totals. These can be
2900 stored in the sort_key field. */
2902 for (hh = h; hh != last; hh = hh->next)
2904 int weight = hh->sort_key % 1000; /* was precedence * 1000 + weight */
2907 if (hh->mx != hh->next->mx) break;
2910 /* If there's more than one host at this precedence (priority), we need to
2911 pick one to go first. */
2917 int randomizer = random_number(sum + 1);
2919 for (ppptr = pptr, hhh = h;
2921 ppptr = &(hhh->next), hhh = hhh->next)
2923 if (hhh->sort_key >= randomizer) break;
2926 /* hhh now points to the host that should go first; ppptr points to the
2927 place that points to it. Unfortunately, if the start of the minilist is
2928 the start of the entire list, we can't just swap the items over, because
2929 we must not change the value of host, since it is passed in from outside.
2930 One day, this could perhaps be changed.
2932 The special case is fudged by putting the new item *second* in the chain,
2933 and then transferring the data between the first and second items. We
2934 can't just swap the first and the chosen item, because that would mean
2935 that an item with zero weight might no longer be first. */
2939 *ppptr = hhh->next; /* Cuts it out of the chain */
2943 host_item temp = *h;
2946 hhh->next = temp.next;
2952 hhh->next = h; /* The rest of the chain follows it */
2953 *pptr = hhh; /* It takes the place of h */
2954 h = hhh; /* It's now the start of this minilist */
2959 /* A host has been chosen to be first at this priority and h now points
2960 to this host. There may be others at the same priority, or others at a
2961 different priority. Before we leave this host, we need to put back a sort
2962 key of the traditional MX kind, in case this host is multihomed, because
2963 the sort key is used for ordering the multiple IP addresses. We do not need
2964 to ensure that these new sort keys actually reflect the order of the hosts,
2967 h->sort_key = h->mx * 1000 + random_number(500);
2968 } /* Move on to the next host */
2971 /* Now we have to find IP addresses for all the hosts. We have ensured above
2972 that the names in all the host items are unique. Before release 4.61 we used to
2973 process records from the additional section in the DNS packet that returned the
2974 MX or SRV records. However, a DNS name server is free to drop any resource
2975 records from the additional section. In theory, this has always been a
2976 potential problem, but it is exacerbated by the advent of IPv6. If a host had
2977 several IPv4 addresses and some were not in the additional section, at least
2978 Exim would try the others. However, if a host had both IPv4 and IPv6 addresses
2979 and all the IPv4 (say) addresses were absent, Exim would try only for a IPv6
2980 connection, and never try an IPv4 address. When there was only IPv4
2981 connectivity, this was a disaster that did in practice occur.
2983 So, from release 4.61 onwards, we always search for A and AAAA records
2984 explicitly. The names shouldn't point to CNAMES, but we use the general lookup
2985 function that handles them, just in case. If any lookup gives a soft error,
2986 change the default yield.
2988 For these DNS lookups, we must disable qualify_single and search_parents;
2989 otherwise invalid host names obtained from MX or SRV records can cause trouble
2990 if they happen to match something local. */
2992 yield = HOST_FIND_FAILED; /* Default yield */
2993 dns_init(FALSE, FALSE, /* Disable qualify_single and search_parents */
2994 dnssec_request || dnssec_require);
2996 for (h = host; h != last->next; h = h->next)
2998 if (h->address != NULL) continue; /* Inserted by a multihomed host */
2999 rc = set_address_from_dns(h, &last, ignore_target_hosts, allow_mx_to_ip,
3000 NULL, dnssec_request, dnssec_require);
3001 if (rc != HOST_FOUND)
3003 h->status = hstatus_unusable;
3004 if (rc == HOST_FIND_AGAIN)
3007 h->why = hwhy_deferred;
3010 h->why = (rc == HOST_IGNORED)? hwhy_ignored : hwhy_failed;
3014 /* Scan the list for any hosts that are marked unusable because they have
3015 been explicitly ignored, and remove them from the list, as if they did not
3016 exist. If we end up with just a single, ignored host, flatten its fields as if
3017 nothing was found. */
3019 if (ignore_target_hosts != NULL)
3021 host_item *prev = NULL;
3022 for (h = host; h != last->next; h = h->next)
3025 if (h->why != hwhy_ignored) /* Non ignored host, just continue */
3027 else if (prev == NULL) /* First host is ignored */
3029 if (h != last) /* First is not last */
3031 if (h->next == last) last = h; /* Overwrite it with next */
3032 *h = *(h->next); /* and reprocess it. */
3033 goto REDO; /* C should have redo, like Perl */
3036 else /* Ignored host is not first - */
3038 prev->next = h->next;
3039 if (h == last) last = prev;
3043 if (host->why == hwhy_ignored) host->address = NULL;
3046 /* There is still one complication in the case of IPv6. Although the code above
3047 arranges that IPv6 addresses take precedence over IPv4 addresses for multihomed
3048 hosts, it doesn't do this for addresses that apply to different hosts with the
3049 same MX precedence, because the sorting on MX precedence happens first. So we
3050 have to make another pass to check for this case. We ensure that, within a
3051 single MX preference value, IPv6 addresses come first. This can separate the
3052 addresses of a multihomed host, but that should not matter. */
3055 if (h != last && !disable_ipv6)
3057 for (h = host; h != last; h = h->next)
3060 host_item *next = h->next;
3061 if (h->mx != next->mx || /* If next is different MX */
3062 h->address == NULL || /* OR this one is unset */
3063 Ustrchr(h->address, ':') != NULL || /* OR this one is IPv6 */
3064 (next->address != NULL &&
3065 Ustrchr(next->address, ':') == NULL)) /* OR next is IPv4 */
3066 continue; /* move on to next */
3067 temp = *h; /* otherwise, swap */
3068 temp.next = next->next;
3076 /* Remove any duplicate IP addresses and then scan the list of hosts for any
3077 whose IP addresses are on the local host. If any are found, all hosts with the
3078 same or higher MX values are removed. However, if the local host has the lowest
3079 numbered MX, then HOST_FOUND_LOCAL is returned. Otherwise, if at least one host
3080 with an IP address is on the list, HOST_FOUND is returned. Otherwise,
3081 HOST_FIND_FAILED is returned, but in this case do not update the yield, as it
3082 might have been set to HOST_FIND_AGAIN just above here. If not, it will already
3083 be HOST_FIND_FAILED. */
3085 host_remove_duplicates(host, &last);
3086 rc = host_scan_for_local_hosts(host, &last, removed);
3087 if (rc != HOST_FIND_FAILED) yield = rc;
3089 DEBUG(D_host_lookup)
3091 if (fully_qualified_name != NULL)
3092 debug_printf("fully qualified name = %s\n", *fully_qualified_name);
3093 debug_printf("host_find_bydns yield = %s (%d); returned hosts:\n",
3094 (yield == HOST_FOUND)? "HOST_FOUND" :
3095 (yield == HOST_FOUND_LOCAL)? "HOST_FOUND_LOCAL" :
3096 (yield == HOST_FIND_AGAIN)? "HOST_FIND_AGAIN" :
3097 (yield == HOST_FIND_FAILED)? "HOST_FIND_FAILED" : "?",
3099 for (h = host; h != last->next; h = h->next)
3101 debug_printf(" %s %s MX=%d %s", h->name,
3102 !h->address ? US"<null>" : h->address, h->mx,
3103 h->dnssec == DS_YES ? US"DNSSEC " : US"");
3104 if (h->port != PORT_NONE) debug_printf("port=%d ", h->port);
3105 if (h->status >= hstatus_unusable) debug_printf("*");
3112 dns_init(FALSE, FALSE, FALSE); /* clear the dnssec bit for getaddrbyname */
3116 /*************************************************
3117 **************************************************
3118 * Stand-alone test program *
3119 **************************************************
3120 *************************************************/
3124 int main(int argc, char **cargv)
3127 int whichrrs = HOST_FIND_BY_MX | HOST_FIND_BY_A;
3128 BOOL byname = FALSE;
3129 BOOL qualify_single = TRUE;
3130 BOOL search_parents = FALSE;
3131 BOOL request_dnssec = FALSE;
3132 BOOL require_dnssec = FALSE;
3133 uschar **argv = USS cargv;
3136 disable_ipv6 = FALSE;
3137 primary_hostname = US"";
3138 store_pool = POOL_MAIN;
3139 debug_selector = D_host_lookup|D_interface;
3140 debug_file = stdout;
3141 debug_fd = fileno(debug_file);
3143 printf("Exim stand-alone host functions test\n");
3145 host_find_interfaces();
3146 debug_selector = D_host_lookup | D_dns;
3148 if (argc > 1) primary_hostname = argv[1];
3150 /* So that debug level changes can be done first */
3152 dns_init(qualify_single, search_parents, FALSE);
3154 printf("Testing host lookup\n");
3156 while (Ufgets(buffer, 256, stdin) != NULL)
3159 int len = Ustrlen(buffer);
3160 uschar *fully_qualified_name;
3162 while (len > 0 && isspace(buffer[len-1])) len--;
3165 if (Ustrcmp(buffer, "q") == 0) break;
3167 if (Ustrcmp(buffer, "byname") == 0) byname = TRUE;
3168 else if (Ustrcmp(buffer, "no_byname") == 0) byname = FALSE;
3169 else if (Ustrcmp(buffer, "a_only") == 0) whichrrs = HOST_FIND_BY_A;
3170 else if (Ustrcmp(buffer, "mx_only") == 0) whichrrs = HOST_FIND_BY_MX;
3171 else if (Ustrcmp(buffer, "srv_only") == 0) whichrrs = HOST_FIND_BY_SRV;
3172 else if (Ustrcmp(buffer, "srv+a") == 0)
3173 whichrrs = HOST_FIND_BY_SRV | HOST_FIND_BY_A;
3174 else if (Ustrcmp(buffer, "srv+mx") == 0)
3175 whichrrs = HOST_FIND_BY_SRV | HOST_FIND_BY_MX;
3176 else if (Ustrcmp(buffer, "srv+mx+a") == 0)
3177 whichrrs = HOST_FIND_BY_SRV | HOST_FIND_BY_MX | HOST_FIND_BY_A;
3178 else if (Ustrcmp(buffer, "qualify_single") == 0) qualify_single = TRUE;
3179 else if (Ustrcmp(buffer, "no_qualify_single") == 0) qualify_single = FALSE;
3180 else if (Ustrcmp(buffer, "search_parents") == 0) search_parents = TRUE;
3181 else if (Ustrcmp(buffer, "no_search_parents") == 0) search_parents = FALSE;
3182 else if (Ustrcmp(buffer, "request_dnssec") == 0) request_dnssec = TRUE;
3183 else if (Ustrcmp(buffer, "no_request_dnssec") == 0) request_dnssec = FALSE;
3184 else if (Ustrcmp(buffer, "require_dnssec") == 0) require_dnssec = TRUE;
3185 else if (Ustrcmp(buffer, "no_reqiret_dnssec") == 0) require_dnssec = FALSE;
3186 else if (Ustrcmp(buffer, "test_harness") == 0)
3187 running_in_test_harness = !running_in_test_harness;
3188 else if (Ustrcmp(buffer, "ipv6") == 0) disable_ipv6 = !disable_ipv6;
3189 else if (Ustrcmp(buffer, "res_debug") == 0)
3191 _res.options ^= RES_DEBUG;
3193 else if (Ustrncmp(buffer, "retrans", 7) == 0)
3195 (void)sscanf(CS(buffer+8), "%d", &dns_retrans);
3196 _res.retrans = dns_retrans;
3198 else if (Ustrncmp(buffer, "retry", 5) == 0)
3200 (void)sscanf(CS(buffer+6), "%d", &dns_retry);
3201 _res.retry = dns_retry;
3205 int flags = whichrrs;
3211 h.status = hstatus_unknown;
3212 h.why = hwhy_unknown;
3215 if (qualify_single) flags |= HOST_FIND_QUALIFY_SINGLE;
3216 if (search_parents) flags |= HOST_FIND_SEARCH_PARENTS;
3219 ? host_find_byname(&h, NULL, flags, &fully_qualified_name, TRUE)
3220 : host_find_bydns(&h, NULL, flags, US"smtp", NULL, NULL,
3221 request_dnssec ? &h.name : NULL,
3222 require_dnssec ? &h.name : NULL,
3223 &fully_qualified_name, NULL);
3225 if (rc == HOST_FIND_FAILED) printf("Failed\n");
3226 else if (rc == HOST_FIND_AGAIN) printf("Again\n");
3227 else if (rc == HOST_FOUND_LOCAL) printf("Local\n");
3233 printf("Testing host_aton\n");
3235 while (Ufgets(buffer, 256, stdin) != NULL)
3239 int len = Ustrlen(buffer);
3241 while (len > 0 && isspace(buffer[len-1])) len--;
3244 if (Ustrcmp(buffer, "q") == 0) break;
3246 len = host_aton(buffer, x);
3247 printf("length = %d ", len);
3248 for (i = 0; i < len; i++)
3250 printf("%04x ", (x[i] >> 16) & 0xffff);
3251 printf("%04x ", x[i] & 0xffff);
3258 printf("Testing host_name_lookup\n");
3260 while (Ufgets(buffer, 256, stdin) != NULL)
3262 int len = Ustrlen(buffer);
3263 while (len > 0 && isspace(buffer[len-1])) len--;
3265 if (Ustrcmp(buffer, "q") == 0) break;
3266 sender_host_address = buffer;
3267 sender_host_name = NULL;
3268 sender_host_aliases = NULL;
3269 host_lookup_msg = US"";
3270 host_lookup_failed = FALSE;
3271 if (host_name_lookup() == FAIL) /* Debug causes printing */
3272 printf("Lookup failed:%s\n", host_lookup_msg);
3280 #endif /* STAND_ALONE */