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a5a28604 | 1 | /* $Cambridge: exim/src/src/routers/rf_lookup_hostlist.c,v 1.3 2005/01/11 15:51:03 ph10 Exp $ */ |
0756eb3c PH |
2 | |
3 | /************************************************* | |
4 | * Exim - an Internet mail transport agent * | |
5 | *************************************************/ | |
6 | ||
c988f1f4 | 7 | /* Copyright (c) University of Cambridge 1995 - 2005 */ |
0756eb3c PH |
8 | /* See the file NOTICE for conditions of use and distribution. */ |
9 | ||
10 | ||
11 | #include "../exim.h" | |
12 | #include "rf_functions.h" | |
13 | ||
14 | ||
15 | ||
16 | /************************************************* | |
17 | * Look up IP addresses for a set of hosts * | |
18 | *************************************************/ | |
19 | ||
20 | /* This function is called by a router to fill in the IP addresses for a set of | |
21 | hosts that are attached to an address. Each host has its name and MX value set; | |
22 | and those that need processing have their address fields set NULL. Multihomed | |
23 | hosts cause additional blocks to be inserted into the chain. | |
24 | ||
25 | This function also supports pseudo-hosts whose names end with "/MX". In this | |
26 | case, MX records are looked up for the name, and the list of hosts obtained | |
27 | replaces the incoming "host". In other words, "x/MX" is shorthand for "those | |
28 | hosts pointed to by x's MX records". | |
29 | ||
30 | Arguments: | |
31 | rblock the router block | |
32 | addr the address being routed | |
33 | ignore_target_hosts list of hosts to ignore | |
34 | lookup_type lk_default or lk_byname or lk_bydns | |
35 | hff_code what to do for host find failed | |
36 | addr_new passed to rf_self_action for self=reroute | |
37 | ||
38 | Returns: OK | |
39 | DEFER host lookup defer | |
40 | PASS timeout etc and pass_on_timeout set | |
41 | self_action: PASS, DECLINE, DEFER, FAIL, FREEZE | |
42 | hff_code after host find failed | |
43 | */ | |
44 | ||
45 | int | |
46 | rf_lookup_hostlist(router_instance *rblock, address_item *addr, | |
47 | uschar *ignore_target_hosts, int lookup_type, int hff_code, | |
48 | address_item **addr_new) | |
49 | { | |
50 | BOOL self_send = FALSE; | |
51 | host_item *h, *next_h, *prev; | |
52 | ||
53 | /* Look up each host address. A lookup may add additional items into the chain | |
54 | if there are multiple addresses. Hence the use of next_h to start each cycle of | |
55 | the loop at the next original host. If any host is identified as being the local | |
56 | host, omit it and any subsequent hosts - i.e. treat the list like an ordered | |
57 | list of MX hosts. If the first host is the local host, act according to the | |
58 | "self" option in the configuration. */ | |
59 | ||
60 | prev = NULL; | |
61 | for (h = addr->host_list; h != NULL; prev = h, h = next_h) | |
62 | { | |
63 | uschar *canonical_name; | |
64 | int rc, len; | |
65 | ||
66 | next_h = h->next; | |
67 | if (h->address != NULL) continue; | |
68 | ||
69 | DEBUG(D_route|D_host_lookup) | |
70 | debug_printf("finding IP address for %s\n", h->name); | |
71 | ||
72 | /* If the name ends with "/MX", we interpret it to mean "the list of hosts | |
73 | pointed to by MX records with this name". */ | |
74 | ||
75 | len = Ustrlen(h->name); | |
76 | if (len > 3 && strcmpic(h->name + len - 3, US"/mx") == 0) | |
77 | { | |
78 | DEBUG(D_route|D_host_lookup) | |
79 | debug_printf("doing DNS MX lookup for %s\n", h->name); | |
80 | ||
81 | h->name[len-3] = 0; | |
82 | rc = host_find_bydns(h, | |
83 | ignore_target_hosts, | |
84 | HOST_FIND_BY_MX, /* look only for MX records */ | |
85 | NULL, /* SRV service not relevant */ | |
86 | NULL, /* failing srv domains not relevant */ | |
87 | NULL, /* no special mx failing domains */ | |
88 | NULL, /* fully_qualified_name */ | |
89 | NULL); /* indicate local host removed */ | |
90 | } | |
91 | ||
92 | /* If explicitly configured to look up by name, or if the "host name" is | |
93 | actually an IP address, do a byname lookup. */ | |
94 | ||
a5a28604 | 95 | else if (lookup_type == lk_byname || string_is_ip_address(h->name, NULL) > 0) |
0756eb3c PH |
96 | { |
97 | DEBUG(D_route|D_host_lookup) debug_printf("calling host_find_byname\n"); | |
98 | rc = host_find_byname(h, ignore_target_hosts, &canonical_name, TRUE); | |
99 | } | |
100 | ||
101 | /* Otherwise, do a DNS lookup. If that yields "host not found", and the | |
102 | lookup type is the default (i.e. "bydns" is not explicitly configured), | |
103 | follow up with a byname lookup, just in case. */ | |
104 | ||
105 | else | |
106 | { | |
107 | BOOL removed; | |
108 | DEBUG(D_route|D_host_lookup) debug_printf("doing DNS lookup\n"); | |
109 | rc = host_find_bydns(h, ignore_target_hosts, HOST_FIND_BY_A, NULL, NULL, | |
110 | NULL, &canonical_name, &removed); | |
111 | if (rc == HOST_FOUND) | |
112 | { | |
113 | if (removed) setflag(addr, af_local_host_removed); | |
114 | } | |
115 | else if (rc == HOST_FIND_FAILED) | |
116 | { | |
117 | if (lookup_type == lk_default) | |
118 | { | |
119 | DEBUG(D_route|D_host_lookup) | |
120 | debug_printf("DNS lookup failed: trying getipnodebyname\n"); | |
121 | rc = host_find_byname(h, ignore_target_hosts, &canonical_name, TRUE); | |
122 | } | |
123 | } | |
124 | } | |
125 | ||
126 | /* Temporary failure defers, unless pass_on_timeout is set */ | |
127 | ||
128 | if (rc == HOST_FIND_AGAIN) | |
129 | { | |
130 | if (rblock->pass_on_timeout) | |
131 | { | |
132 | DEBUG(D_route) | |
133 | debug_printf("%s router timed out and pass_on_timeout set\n", | |
134 | rblock->name); | |
135 | return PASS; | |
136 | } | |
137 | addr->message = string_sprintf("host lookup for %s did not complete " | |
138 | "(DNS timeout?)", h->name); | |
139 | addr->basic_errno = ERRNO_DNSDEFER; | |
140 | return DEFER; | |
141 | } | |
142 | ||
143 | /* Permanent failure is controlled by host_find_failed */ | |
144 | ||
145 | if (rc == HOST_FIND_FAILED) | |
146 | { | |
147 | if (hff_code == hff_pass) return PASS; | |
148 | if (hff_code == hff_decline) return DECLINE; | |
149 | ||
150 | addr->message = | |
151 | string_sprintf("lookup of host \"%s\" failed in %s router%s", | |
152 | h->name, rblock->name, | |
153 | host_find_failed_syntax? ": syntax error in name" : ""); | |
154 | ||
155 | if (hff_code == hff_defer) return DEFER; | |
156 | if (hff_code == hff_fail) return FAIL; | |
157 | ||
158 | addr->special_action = SPECIAL_FREEZE; | |
159 | return DEFER; | |
160 | } | |
161 | ||
162 | /* A local host gets chopped, with its successors, if there are previous | |
163 | hosts. Otherwise the self option is used. If it is set to "send", any | |
164 | subsequent hosts that are also the local host do NOT get chopped. */ | |
165 | ||
166 | if (rc == HOST_FOUND_LOCAL && !self_send) | |
167 | { | |
168 | if (prev != NULL) | |
169 | { | |
170 | DEBUG(D_route) | |
171 | { | |
172 | debug_printf("Removed from host list:\n"); | |
173 | for (; h != NULL; h = h->next) debug_printf(" %s\n", h->name); | |
174 | } | |
175 | prev->next = NULL; | |
176 | setflag(addr, af_local_host_removed); | |
177 | break; | |
178 | } | |
179 | rc = rf_self_action(addr, h, rblock->self_code, rblock->self_rewrite, | |
180 | rblock->self, addr_new); | |
181 | if (rc != OK) | |
182 | { | |
183 | addr->host_list = NULL; /* Kill the host list for */ | |
184 | return rc; /* anything other than "send" */ | |
185 | } | |
186 | self_send = TRUE; | |
187 | } | |
188 | } | |
189 | ||
190 | return OK; | |
191 | } | |
192 | ||
193 | /* End of rf_lookup_hostlist.c */ |