1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
5 /* Copyright (c) University of Cambridge 1995 - 2009 */
6 /* See the file NOTICE for conditions of use and distribution. */
10 #include "rf_functions.h"
14 /*************************************************
15 * Look up IP addresses for a set of hosts *
16 *************************************************/
18 /* This function is called by a router to fill in the IP addresses for a set of
19 hosts that are attached to an address. Each host has its name and MX value set;
20 and those that need processing have their address fields set NULL. Multihomed
21 hosts cause additional blocks to be inserted into the chain.
23 This function also supports pseudo-hosts whose names end with "/MX". In this
24 case, MX records are looked up for the name, and the list of hosts obtained
25 replaces the incoming "host". In other words, "x/MX" is shorthand for "those
26 hosts pointed to by x's MX records".
28 It is also possible for a port to be specified along with the host name or IP
29 address. The syntax is to add ":port" on to the end. This doesn't work with
30 IPv6 addresses, so we allow IP addresses to be enclosed in [] in order to make
31 this work. The specification of the port must come last, that is, after "/MX"
35 rblock the router block
36 addr the address being routed
37 ignore_target_hosts list of hosts to ignore
38 lookup_type lk_default or lk_byname or lk_bydns
39 hff_code what to do for host find failed
40 addr_new passed to rf_self_action for self=reroute
43 DEFER host lookup defer
44 PASS timeout etc and pass_on_timeout set
45 self_action: PASS, DECLINE, DEFER, FAIL, FREEZE
46 hff_code after host find failed
50 rf_lookup_hostlist(router_instance *rblock, address_item *addr,
51 uschar *ignore_target_hosts, int lookup_type, int hff_code,
52 address_item **addr_new)
54 BOOL self_send = FALSE;
55 host_item *h, *next_h, *prev;
57 /* Look up each host address. A lookup may add additional items into the chain
58 if there are multiple addresses. Hence the use of next_h to start each cycle of
59 the loop at the next original host. If any host is identified as being the local
60 host, omit it and any subsequent hosts - i.e. treat the list like an ordered
61 list of MX hosts. If the first host is the local host, act according to the
62 "self" option in the configuration. */
65 for (h = addr->host_list; h != NULL; h = next_h)
67 uschar *canonical_name;
71 if (h->address != NULL) { prev = h; continue; }
73 DEBUG(D_route|D_host_lookup)
74 debug_printf("finding IP address for %s\n", h->name);
76 /* Handle any port setting that may be on the name; it will be removed
77 from the end of the name. */
79 port = host_item_get_port(h);
81 /* If the name ends with "/MX", we interpret it to mean "the list of hosts
82 pointed to by MX records with this name". */
84 len = Ustrlen(h->name);
85 if (len > 3 && strcmpic(h->name + len - 3, US"/mx") == 0)
87 DEBUG(D_route|D_host_lookup)
88 debug_printf("doing DNS MX lookup for %s\n", h->name);
90 h->name = string_copyn(h->name, len - 3);
91 rc = host_find_bydns(h,
93 HOST_FIND_BY_MX, /* look only for MX records */
94 NULL, /* SRV service not relevant */
95 NULL, /* failing srv domains not relevant */
96 NULL, /* no special mx failing domains */
97 NULL, /* fully_qualified_name */
98 NULL); /* indicate local host removed */
101 /* If explicitly configured to look up by name, or if the "host name" is
102 actually an IP address, do a byname lookup. */
104 else if (lookup_type == lk_byname || string_is_ip_address(h->name, NULL) != 0)
106 DEBUG(D_route|D_host_lookup) debug_printf("calling host_find_byname\n");
107 rc = host_find_byname(h, ignore_target_hosts, HOST_FIND_QUALIFY_SINGLE,
108 &canonical_name, TRUE);
111 /* Otherwise, do a DNS lookup. If that yields "host not found", and the
112 lookup type is the default (i.e. "bydns" is not explicitly configured),
113 follow up with a byname lookup, just in case. */
118 DEBUG(D_route|D_host_lookup) debug_printf("doing DNS lookup\n");
119 rc = host_find_bydns(h, ignore_target_hosts, HOST_FIND_BY_A, NULL, NULL,
120 NULL, &canonical_name, &removed);
121 if (rc == HOST_FOUND)
123 if (removed) setflag(addr, af_local_host_removed);
125 else if (rc == HOST_FIND_FAILED)
127 if (lookup_type == lk_default)
129 DEBUG(D_route|D_host_lookup)
130 debug_printf("DNS lookup failed: trying getipnodebyname\n");
131 rc = host_find_byname(h, ignore_target_hosts, HOST_FIND_QUALIFY_SINGLE,
132 &canonical_name, TRUE);
137 /* Temporary failure defers, unless pass_on_timeout is set */
139 if (rc == HOST_FIND_AGAIN)
141 if (rblock->pass_on_timeout)
144 debug_printf("%s router timed out and pass_on_timeout set\n",
148 addr->message = string_sprintf("host lookup for %s did not complete "
149 "(DNS timeout?)", h->name);
150 addr->basic_errno = ERRNO_DNSDEFER;
154 /* Permanent failure is controlled by host_find_failed */
156 if (rc == HOST_FIND_FAILED)
158 if (hff_code == hff_ignore)
160 if (prev == NULL) addr->host_list = next_h; else prev->next = next_h;
161 continue; /* With the next host, leave prev unchanged */
164 if (hff_code == hff_pass) return PASS;
165 if (hff_code == hff_decline) return DECLINE;
168 string_sprintf("lookup of host \"%s\" failed in %s router%s",
169 h->name, rblock->name,
170 host_find_failed_syntax? ": syntax error in name" : "");
172 if (hff_code == hff_defer) return DEFER;
173 if (hff_code == hff_fail) return FAIL;
175 addr->special_action = SPECIAL_FREEZE;
179 /* Deal with a port setting */
181 if (port != PORT_NONE)
184 for (hh = h; hh != next_h; hh = hh->next) hh->port = port;
187 /* A local host gets chopped, with its successors, if there are previous
188 hosts. Otherwise the self option is used. If it is set to "send", any
189 subsequent hosts that are also the local host do NOT get chopped. */
191 if (rc == HOST_FOUND_LOCAL && !self_send)
197 debug_printf("Removed from host list:\n");
198 for (; h != NULL; h = h->next) debug_printf(" %s\n", h->name);
201 setflag(addr, af_local_host_removed);
204 rc = rf_self_action(addr, h, rblock->self_code, rblock->self_rewrite,
205 rblock->self, addr_new);
208 addr->host_list = NULL; /* Kill the host list for */
209 return rc; /* anything other than "send" */
214 /* Ensure that prev is the host before next_h; this will not be h if a lookup
215 found multiple addresses or multiple MX records. */
218 while (prev->next != next_h) prev = prev->next;
224 /* End of rf_lookup_hostlist.c */