7f7ab6d0d04e3c7082e6e1b70dcfb942790e901e
[exim.git] / src / src / routers / rf_lookup_hostlist.c
1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
4
5 /* Copyright (c) University of Cambridge 1995 - 2015 */
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
38 lookup_type LK_DEFAULT or LK_BYNAME or LK_BYDNS,
39 plus LK_IPV4_{ONLY,PREFER}
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
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. */
63
64 for (host_item * prev = NULL, * h = addr->host_list, *next_h; h; h = next_h)
65 {
66 const uschar *canonical_name;
67 int rc, len, port, mx, sort_key;
68
69 next_h = h->next;
70 if (h->address) { prev = h; continue; }
71
72 DEBUG(D_route|D_host_lookup)
73 debug_printf("finding IP address for %s\n", h->name);
74
75 /* Handle any port setting that may be on the name; it will be removed
76 from the end of the name. */
77
78 port = host_item_get_port(h);
79
80 /* Store the previous mx and sort_key values, which were assigned in
81 host_build_hostlist and will be overwritten by host_find_bydns. */
82
83 mx = h->mx;
84 sort_key = h->sort_key;
85
86 /* If the name ends with "/MX", we interpret it to mean "the list of hosts
87 pointed to by MX records with this name", and the MX record values override
88 the ordering from host_build_hostlist. */
89
90 len = Ustrlen(h->name);
91 if (len > 3 && strcmpic(h->name + len - 3, US"/mx") == 0)
92 {
93 int whichrrs = lookup_type & LK_IPV4_ONLY
94 ? HOST_FIND_BY_MX | HOST_FIND_IPV4_ONLY
95 : lookup_type & LK_IPV4_PREFER
96 ? HOST_FIND_BY_MX | HOST_FIND_IPV4_FIRST
97 : HOST_FIND_BY_MX;
98
99 DEBUG(D_route|D_host_lookup)
100 debug_printf("doing DNS MX lookup for %s\n", h->name);
101
102 mx = MX_NONE;
103 h->name = string_copyn(h->name, len - 3);
104 rc = host_find_bydns(h,
105 ignore_target_hosts,
106 whichrrs, /* look only for MX records */
107 NULL, /* SRV service not relevant */
108 NULL, /* failing srv domains not relevant */
109 NULL, /* no special mx failing domains */
110 &rblock->dnssec, /* dnssec request/require */
111 NULL, /* fully_qualified_name */
112 NULL); /* indicate local host removed */
113 }
114
115 /* If explicitly configured to look up by name, or if the "host name" is
116 actually an IP address, do a byname lookup. */
117
118 else if (lookup_type & LK_BYNAME || string_is_ip_address(h->name, NULL) != 0)
119 {
120 DEBUG(D_route|D_host_lookup) debug_printf("calling host_find_byname\n");
121 rc = host_find_byname(h, ignore_target_hosts, HOST_FIND_QUALIFY_SINGLE,
122 &canonical_name, TRUE);
123 }
124
125 /* Otherwise, do a DNS lookup. If that yields "host not found", and the
126 lookup type is the default (i.e. "bydns" is not explicitly configured),
127 follow up with a byname lookup, just in case. */
128
129 else
130 {
131 BOOL removed;
132 int whichrrs = lookup_type & LK_IPV4_ONLY
133 ? HOST_FIND_BY_A
134 : lookup_type & LK_IPV4_PREFER
135 ? HOST_FIND_BY_A | HOST_FIND_BY_AAAA | HOST_FIND_IPV4_FIRST
136 : HOST_FIND_BY_A | HOST_FIND_BY_AAAA;
137
138 DEBUG(D_route|D_host_lookup) debug_printf("doing DNS lookup\n");
139 switch (rc = host_find_bydns(h, ignore_target_hosts, whichrrs, NULL,
140 NULL, NULL,
141 &rblock->dnssec, /* domains for request/require */
142 &canonical_name, &removed))
143 {
144 case HOST_FOUND:
145 if (removed) setflag(addr, af_local_host_removed);
146 break;
147 case HOST_FIND_FAILED:
148 if (lookup_type & LK_DEFAULT)
149 {
150 DEBUG(D_route|D_host_lookup)
151 debug_printf("DNS lookup failed: trying getipnodebyname\n");
152 rc = host_find_byname(h, ignore_target_hosts, HOST_FIND_QUALIFY_SINGLE,
153 &canonical_name, TRUE);
154 }
155 break;
156 }
157 }
158
159 /* Temporary failure defers, unless pass_on_timeout is set */
160
161 if (rc == HOST_FIND_SECURITY)
162 {
163 addr->message = string_sprintf("host lookup for %s done insecurely" , h->name);
164 addr->basic_errno = ERRNO_DNSDEFER;
165 return DEFER;
166 }
167 if (rc == HOST_FIND_AGAIN)
168 {
169 if (rblock->pass_on_timeout)
170 {
171 DEBUG(D_route)
172 debug_printf("%s router timed out and pass_on_timeout set\n",
173 rblock->name);
174 return PASS;
175 }
176 addr->message = string_sprintf("host lookup for %s did not complete "
177 "(DNS timeout?)", h->name);
178 addr->basic_errno = ERRNO_DNSDEFER;
179 return DEFER;
180 }
181
182 /* Permanent failure is controlled by host_find_failed */
183
184 if (rc == HOST_FIND_FAILED)
185 {
186 if (hff_code == hff_ignore)
187 {
188 if (prev == NULL) addr->host_list = next_h; else prev->next = next_h;
189 continue; /* With the next host, leave prev unchanged */
190 }
191
192 if (hff_code == hff_pass) return PASS;
193 if (hff_code == hff_decline) return DECLINE;
194
195 addr->basic_errno = ERRNO_UNKNOWNHOST;
196 addr->message =
197 string_sprintf("lookup of host \"%s\" failed in %s router%s",
198 h->name, rblock->name,
199 f.host_find_failed_syntax? ": syntax error in name" : "");
200
201 if (hff_code == hff_defer) return DEFER;
202 if (hff_code == hff_fail) return FAIL;
203
204 addr->special_action = SPECIAL_FREEZE;
205 return DEFER;
206 }
207
208 /* Deal with the settings that were previously cleared:
209 port, mx and sort_key. */
210
211 if (port != PORT_NONE)
212 for (host_item * hh = h; hh != next_h; hh = hh->next)
213 hh->port = port;
214
215 if (mx != MX_NONE)
216 for (host_item * hh = h; hh != next_h; hh = hh->next)
217 {
218 hh->mx = mx;
219 hh->sort_key = sort_key;
220 }
221
222 /* A local host gets chopped, with its successors, if there are previous
223 hosts. Otherwise the self option is used. If it is set to "send", any
224 subsequent hosts that are also the local host do NOT get chopped. */
225
226 if (rc == HOST_FOUND_LOCAL && !self_send)
227 {
228 if (prev)
229 {
230 DEBUG(D_route)
231 {
232 debug_printf("Removed from host list:\n");
233 for (; h; h = h->next) debug_printf(" %s\n", h->name);
234 }
235 prev->next = NULL;
236 setflag(addr, af_local_host_removed);
237 break;
238 }
239 rc = rf_self_action(addr, h, rblock->self_code, rblock->self_rewrite,
240 rblock->self, addr_new);
241 if (rc != OK)
242 {
243 addr->host_list = NULL; /* Kill the host list for */
244 return rc; /* anything other than "send" */
245 }
246 self_send = TRUE;
247 }
248
249 /* Ensure that prev is the host before next_h; this will not be h if a lookup
250 found multiple addresses or multiple MX records. */
251
252 prev = h;
253 while (prev->next != next_h) prev = prev->next;
254 }
255
256 return OK;
257 }
258
259 /* End of rf_lookup_hostlist.c */