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420a0d19 CE |
1 | /************************************************* |
2 | * Exim - an Internet mail transport agent * | |
3 | *************************************************/ | |
4 | ||
2ea97746 | 5 | /* Copyright (c) University of Cambridge 1995 - 2015 */ |
420a0d19 CE |
6 | /* See the file NOTICE for conditions of use and distribution. */ |
7 | ||
8 | ||
9 | #include "../exim.h" | |
10 | #include "rf_functions.h" | |
11 | ||
12 | ||
13 | ||
14 | /************************************************* | |
15 | * Look up IP addresses for a set of hosts * | |
16 | *************************************************/ | |
17 | ||
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. | |
22 | ||
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". | |
27 | ||
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" | |
32 | if that is present. | |
33 | ||
34 | Arguments: | |
35 | rblock the router block | |
36 | addr the address being routed | |
37 | ignore_target_hosts list of hosts to ignore | |
2ea97746 CE |
38 | lookup_type LK_DEFAULT or LK_BYNAME or LK_BYDNS, |
39 | plus LK_IPV4_{ONLY,PREFER} | |
420a0d19 CE |
40 | hff_code what to do for host find failed |
41 | addr_new passed to rf_self_action for self=reroute | |
42 | ||
43 | Returns: OK | |
44 | DEFER host lookup defer | |
45 | PASS timeout etc and pass_on_timeout set | |
46 | self_action: PASS, DECLINE, DEFER, FAIL, FREEZE | |
47 | hff_code after host find failed | |
48 | */ | |
49 | ||
50 | int | |
51 | rf_lookup_hostlist(router_instance *rblock, address_item *addr, | |
52 | uschar *ignore_target_hosts, int lookup_type, int hff_code, | |
53 | address_item **addr_new) | |
54 | { | |
55 | BOOL self_send = FALSE; | |
56 | host_item *h, *next_h, *prev; | |
57 | ||
58 | /* Look up each host address. A lookup may add additional items into the chain | |
59 | if there are multiple addresses. Hence the use of next_h to start each cycle of | |
60 | the loop at the next original host. If any host is identified as being the local | |
61 | host, omit it and any subsequent hosts - i.e. treat the list like an ordered | |
62 | list of MX hosts. If the first host is the local host, act according to the | |
63 | "self" option in the configuration. */ | |
64 | ||
2ea97746 | 65 | for (prev = NULL, h = addr->host_list; h; h = next_h) |
420a0d19 | 66 | { |
2ea97746 CE |
67 | const uschar *canonical_name; |
68 | int rc, len, port, mx, sort_key; | |
420a0d19 CE |
69 | |
70 | next_h = h->next; | |
2ea97746 | 71 | if (h->address) { prev = h; continue; } |
420a0d19 CE |
72 | |
73 | DEBUG(D_route|D_host_lookup) | |
74 | debug_printf("finding IP address for %s\n", h->name); | |
75 | ||
76 | /* Handle any port setting that may be on the name; it will be removed | |
77 | from the end of the name. */ | |
78 | ||
79 | port = host_item_get_port(h); | |
80 | ||
2ea97746 CE |
81 | /* Store the previous mx and sort_key values, which were assigned in |
82 | host_build_hostlist and will be overwritten by host_find_bydns. */ | |
83 | ||
84 | mx = h->mx; | |
85 | sort_key = h->sort_key; | |
86 | ||
420a0d19 | 87 | /* If the name ends with "/MX", we interpret it to mean "the list of hosts |
2ea97746 CE |
88 | pointed to by MX records with this name", and the MX record values override |
89 | the ordering from host_build_hostlist. */ | |
420a0d19 CE |
90 | |
91 | len = Ustrlen(h->name); | |
92 | if (len > 3 && strcmpic(h->name + len - 3, US"/mx") == 0) | |
93 | { | |
2ea97746 CE |
94 | int whichrrs = lookup_type & LK_IPV4_ONLY |
95 | ? HOST_FIND_BY_MX | HOST_FIND_IPV4_ONLY | |
96 | : lookup_type & LK_IPV4_PREFER | |
97 | ? HOST_FIND_BY_MX | HOST_FIND_IPV4_FIRST | |
98 | : HOST_FIND_BY_MX; | |
99 | ||
420a0d19 CE |
100 | DEBUG(D_route|D_host_lookup) |
101 | debug_printf("doing DNS MX lookup for %s\n", h->name); | |
102 | ||
2ea97746 | 103 | mx = MX_NONE; |
420a0d19 CE |
104 | h->name = string_copyn(h->name, len - 3); |
105 | rc = host_find_bydns(h, | |
106 | ignore_target_hosts, | |
2ea97746 CE |
107 | whichrrs, /* look only for MX records */ |
108 | NULL, /* SRV service not relevant */ | |
109 | NULL, /* failing srv domains not relevant */ | |
110 | NULL, /* no special mx failing domains */ | |
111 | &rblock->dnssec, /* dnssec request/require */ | |
112 | NULL, /* fully_qualified_name */ | |
113 | NULL); /* indicate local host removed */ | |
420a0d19 CE |
114 | } |
115 | ||
116 | /* If explicitly configured to look up by name, or if the "host name" is | |
117 | actually an IP address, do a byname lookup. */ | |
118 | ||
2ea97746 | 119 | else if (lookup_type & LK_BYNAME || string_is_ip_address(h->name, NULL) != 0) |
420a0d19 CE |
120 | { |
121 | DEBUG(D_route|D_host_lookup) debug_printf("calling host_find_byname\n"); | |
122 | rc = host_find_byname(h, ignore_target_hosts, HOST_FIND_QUALIFY_SINGLE, | |
123 | &canonical_name, TRUE); | |
124 | } | |
125 | ||
126 | /* Otherwise, do a DNS lookup. If that yields "host not found", and the | |
127 | lookup type is the default (i.e. "bydns" is not explicitly configured), | |
128 | follow up with a byname lookup, just in case. */ | |
129 | ||
130 | else | |
131 | { | |
132 | BOOL removed; | |
2ea97746 CE |
133 | int whichrrs = lookup_type & LK_IPV4_ONLY |
134 | ? HOST_FIND_BY_A | |
135 | : lookup_type & LK_IPV4_PREFER | |
136 | ? HOST_FIND_BY_A | HOST_FIND_BY_AAAA | HOST_FIND_IPV4_FIRST | |
137 | : HOST_FIND_BY_A | HOST_FIND_BY_AAAA; | |
138 | ||
420a0d19 | 139 | DEBUG(D_route|D_host_lookup) debug_printf("doing DNS lookup\n"); |
2ea97746 CE |
140 | switch (rc = host_find_bydns(h, ignore_target_hosts, whichrrs, NULL, |
141 | NULL, NULL, | |
142 | &rblock->dnssec, /* domains for request/require */ | |
143 | &canonical_name, &removed)) | |
420a0d19 | 144 | { |
2ea97746 CE |
145 | case HOST_FOUND: |
146 | if (removed) setflag(addr, af_local_host_removed); | |
147 | break; | |
148 | case HOST_FIND_FAILED: | |
149 | if (lookup_type & LK_DEFAULT) | |
150 | { | |
151 | DEBUG(D_route|D_host_lookup) | |
152 | debug_printf("DNS lookup failed: trying getipnodebyname\n"); | |
153 | rc = host_find_byname(h, ignore_target_hosts, HOST_FIND_QUALIFY_SINGLE, | |
154 | &canonical_name, TRUE); | |
155 | } | |
156 | break; | |
420a0d19 CE |
157 | } |
158 | } | |
159 | ||
160 | /* Temporary failure defers, unless pass_on_timeout is set */ | |
161 | ||
2ea97746 CE |
162 | if (rc == HOST_FIND_SECURITY) |
163 | { | |
164 | addr->message = string_sprintf("host lookup for %s done insecurely" , h->name); | |
165 | addr->basic_errno = ERRNO_DNSDEFER; | |
166 | return DEFER; | |
167 | } | |
420a0d19 CE |
168 | if (rc == HOST_FIND_AGAIN) |
169 | { | |
170 | if (rblock->pass_on_timeout) | |
171 | { | |
172 | DEBUG(D_route) | |
173 | debug_printf("%s router timed out and pass_on_timeout set\n", | |
174 | rblock->name); | |
175 | return PASS; | |
176 | } | |
177 | addr->message = string_sprintf("host lookup for %s did not complete " | |
178 | "(DNS timeout?)", h->name); | |
179 | addr->basic_errno = ERRNO_DNSDEFER; | |
180 | return DEFER; | |
181 | } | |
182 | ||
183 | /* Permanent failure is controlled by host_find_failed */ | |
184 | ||
185 | if (rc == HOST_FIND_FAILED) | |
186 | { | |
187 | if (hff_code == hff_ignore) | |
188 | { | |
189 | if (prev == NULL) addr->host_list = next_h; else prev->next = next_h; | |
190 | continue; /* With the next host, leave prev unchanged */ | |
191 | } | |
192 | ||
193 | if (hff_code == hff_pass) return PASS; | |
194 | if (hff_code == hff_decline) return DECLINE; | |
195 | ||
2ea97746 | 196 | addr->basic_errno = ERRNO_UNKNOWNHOST; |
420a0d19 CE |
197 | addr->message = |
198 | string_sprintf("lookup of host \"%s\" failed in %s router%s", | |
199 | h->name, rblock->name, | |
2ea97746 | 200 | f.host_find_failed_syntax? ": syntax error in name" : ""); |
420a0d19 CE |
201 | |
202 | if (hff_code == hff_defer) return DEFER; | |
203 | if (hff_code == hff_fail) return FAIL; | |
204 | ||
205 | addr->special_action = SPECIAL_FREEZE; | |
206 | return DEFER; | |
207 | } | |
208 | ||
2ea97746 CE |
209 | /* Deal with the settings that were previously cleared: |
210 | port, mx and sort_key. */ | |
420a0d19 CE |
211 | |
212 | if (port != PORT_NONE) | |
213 | { | |
214 | host_item *hh; | |
215 | for (hh = h; hh != next_h; hh = hh->next) hh->port = port; | |
216 | } | |
217 | ||
2ea97746 CE |
218 | if (mx != MX_NONE) |
219 | { | |
220 | host_item *hh; | |
221 | for (hh = h; hh != next_h; hh = hh->next) | |
222 | { | |
223 | hh->mx = mx; | |
224 | hh->sort_key = sort_key; | |
225 | } | |
226 | } | |
227 | ||
420a0d19 CE |
228 | /* A local host gets chopped, with its successors, if there are previous |
229 | hosts. Otherwise the self option is used. If it is set to "send", any | |
230 | subsequent hosts that are also the local host do NOT get chopped. */ | |
231 | ||
232 | if (rc == HOST_FOUND_LOCAL && !self_send) | |
233 | { | |
2ea97746 | 234 | if (prev) |
420a0d19 CE |
235 | { |
236 | DEBUG(D_route) | |
237 | { | |
238 | debug_printf("Removed from host list:\n"); | |
239 | for (; h != NULL; h = h->next) debug_printf(" %s\n", h->name); | |
240 | } | |
241 | prev->next = NULL; | |
242 | setflag(addr, af_local_host_removed); | |
243 | break; | |
244 | } | |
245 | rc = rf_self_action(addr, h, rblock->self_code, rblock->self_rewrite, | |
246 | rblock->self, addr_new); | |
247 | if (rc != OK) | |
248 | { | |
249 | addr->host_list = NULL; /* Kill the host list for */ | |
250 | return rc; /* anything other than "send" */ | |
251 | } | |
252 | self_send = TRUE; | |
253 | } | |
254 | ||
255 | /* Ensure that prev is the host before next_h; this will not be h if a lookup | |
256 | found multiple addresses or multiple MX records. */ | |
257 | ||
258 | prev = h; | |
259 | while (prev->next != next_h) prev = prev->next; | |
260 | } | |
261 | ||
262 | return OK; | |
263 | } | |
264 | ||
265 | /* End of rf_lookup_hostlist.c */ |