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0756eb3c PH |
1 | /************************************************* |
2 | * Exim - an Internet mail transport agent * | |
3 | *************************************************/ | |
4 | ||
3386088d | 5 | /* Copyright (c) University of Cambridge 1995 - 2015 */ |
1e1ddfac | 6 | /* Copyright (c) The Exim Maintainers 2020 */ |
0756eb3c PH |
7 | /* See the file NOTICE for conditions of use and distribution. */ |
8 | ||
9 | ||
10 | #include "../exim.h" | |
11 | #include "rf_functions.h" | |
12 | ||
13 | ||
14 | ||
15 | /************************************************* | |
16 | * Look up IP addresses for a set of hosts * | |
17 | *************************************************/ | |
18 | ||
19 | /* This function is called by a router to fill in the IP addresses for a set of | |
20 | hosts that are attached to an address. Each host has its name and MX value set; | |
21 | and those that need processing have their address fields set NULL. Multihomed | |
22 | hosts cause additional blocks to be inserted into the chain. | |
23 | ||
24 | This function also supports pseudo-hosts whose names end with "/MX". In this | |
25 | case, MX records are looked up for the name, and the list of hosts obtained | |
26 | replaces the incoming "host". In other words, "x/MX" is shorthand for "those | |
27 | hosts pointed to by x's MX records". | |
28 | ||
7cd1141b PH |
29 | It is also possible for a port to be specified along with the host name or IP |
30 | address. The syntax is to add ":port" on to the end. This doesn't work with | |
31 | IPv6 addresses, so we allow IP addresses to be enclosed in [] in order to make | |
32 | this work. The specification of the port must come last, that is, after "/MX" | |
33 | if that is present. | |
34 | ||
0756eb3c PH |
35 | Arguments: |
36 | rblock the router block | |
37 | addr the address being routed | |
38 | ignore_target_hosts list of hosts to ignore | |
66387a73 JH |
39 | lookup_type LK_DEFAULT or LK_BYNAME or LK_BYDNS, |
40 | plus LK_IPV4_{ONLY,PREFER} | |
0756eb3c PH |
41 | hff_code what to do for host find failed |
42 | addr_new passed to rf_self_action for self=reroute | |
43 | ||
44 | Returns: OK | |
45 | DEFER host lookup defer | |
46 | PASS timeout etc and pass_on_timeout set | |
47 | self_action: PASS, DECLINE, DEFER, FAIL, FREEZE | |
48 | hff_code after host find failed | |
49 | */ | |
50 | ||
51 | int | |
52 | rf_lookup_hostlist(router_instance *rblock, address_item *addr, | |
53 | uschar *ignore_target_hosts, int lookup_type, int hff_code, | |
54 | address_item **addr_new) | |
55 | { | |
56 | BOOL self_send = FALSE; | |
0756eb3c PH |
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 | ||
d7978c0f | 65 | for (host_item * prev = NULL, * h = addr->host_list, *next_h; h; h = next_h) |
0756eb3c | 66 | { |
55414b25 | 67 | const uschar *canonical_name; |
fff1b300 | 68 | int rc, len, port, mx, sort_key; |
0756eb3c PH |
69 | |
70 | next_h = h->next; | |
fff1b300 | 71 | if (h->address) { prev = h; continue; } |
0756eb3c PH |
72 | |
73 | DEBUG(D_route|D_host_lookup) | |
74 | debug_printf("finding IP address for %s\n", h->name); | |
75 | ||
7cd1141b PH |
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 | ||
fff1b300 EA |
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 | ||
0756eb3c | 87 | /* If the name ends with "/MX", we interpret it to mean "the list of hosts |
fff1b300 EA |
88 | pointed to by MX records with this name", and the MX record values override |
89 | the ordering from host_build_hostlist. */ | |
0756eb3c PH |
90 | |
91 | len = Ustrlen(h->name); | |
92 | if (len > 3 && strcmpic(h->name + len - 3, US"/mx") == 0) | |
93 | { | |
66387a73 JH |
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 | ||
0756eb3c PH |
100 | DEBUG(D_route|D_host_lookup) |
101 | debug_printf("doing DNS MX lookup for %s\n", h->name); | |
102 | ||
fff1b300 | 103 | mx = MX_NONE; |
7cd1141b | 104 | h->name = string_copyn(h->name, len - 3); |
0756eb3c PH |
105 | rc = host_find_bydns(h, |
106 | ignore_target_hosts, | |
66387a73 JH |
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 */ | |
7cd171b7 | 111 | &rblock->dnssec, /* dnssec request/require */ |
66387a73 JH |
112 | NULL, /* fully_qualified_name */ |
113 | NULL); /* indicate local host removed */ | |
0756eb3c PH |
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 | ||
66387a73 | 119 | else if (lookup_type & LK_BYNAME || string_is_ip_address(h->name, NULL) != 0) |
0756eb3c PH |
120 | { |
121 | DEBUG(D_route|D_host_lookup) debug_printf("calling host_find_byname\n"); | |
322050c2 PH |
122 | rc = host_find_byname(h, ignore_target_hosts, HOST_FIND_QUALIFY_SINGLE, |
123 | &canonical_name, TRUE); | |
0756eb3c PH |
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; | |
66387a73 JH |
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 | ||
0756eb3c | 139 | DEBUG(D_route|D_host_lookup) debug_printf("doing DNS lookup\n"); |
66387a73 | 140 | switch (rc = host_find_bydns(h, ignore_target_hosts, whichrrs, NULL, |
fff1b300 EA |
141 | NULL, NULL, |
142 | &rblock->dnssec, /* domains for request/require */ | |
143 | &canonical_name, &removed)) | |
0756eb3c | 144 | { |
fff1b300 EA |
145 | case HOST_FOUND: |
146 | if (removed) setflag(addr, af_local_host_removed); | |
147 | break; | |
148 | case HOST_FIND_FAILED: | |
66387a73 | 149 | if (lookup_type & LK_DEFAULT) |
fff1b300 EA |
150 | { |
151 | DEBUG(D_route|D_host_lookup) | |
a06afb97 JH |
152 | debug_printf("DNS lookup failed: trying %s\n", |
153 | f.running_in_test_harness | |
154 | ? "host_fake_gethostbyname" : "getipnodebyname"); | |
fff1b300 EA |
155 | rc = host_find_byname(h, ignore_target_hosts, HOST_FIND_QUALIFY_SINGLE, |
156 | &canonical_name, TRUE); | |
157 | } | |
158 | break; | |
0756eb3c PH |
159 | } |
160 | } | |
161 | ||
162 | /* Temporary failure defers, unless pass_on_timeout is set */ | |
163 | ||
2546388c JH |
164 | if (rc == HOST_FIND_SECURITY) |
165 | { | |
166 | addr->message = string_sprintf("host lookup for %s done insecurely" , h->name); | |
167 | addr->basic_errno = ERRNO_DNSDEFER; | |
168 | return DEFER; | |
169 | } | |
0756eb3c PH |
170 | if (rc == HOST_FIND_AGAIN) |
171 | { | |
172 | if (rblock->pass_on_timeout) | |
173 | { | |
174 | DEBUG(D_route) | |
175 | debug_printf("%s router timed out and pass_on_timeout set\n", | |
176 | rblock->name); | |
177 | return PASS; | |
178 | } | |
179 | addr->message = string_sprintf("host lookup for %s did not complete " | |
180 | "(DNS timeout?)", h->name); | |
181 | addr->basic_errno = ERRNO_DNSDEFER; | |
182 | return DEFER; | |
183 | } | |
184 | ||
185 | /* Permanent failure is controlled by host_find_failed */ | |
186 | ||
187 | if (rc == HOST_FIND_FAILED) | |
188 | { | |
c456d9bb PH |
189 | if (hff_code == hff_ignore) |
190 | { | |
191 | if (prev == NULL) addr->host_list = next_h; else prev->next = next_h; | |
cd9868ec | 192 | continue; /* With the next host, leave prev unchanged */ |
c456d9bb PH |
193 | } |
194 | ||
0756eb3c PH |
195 | if (hff_code == hff_pass) return PASS; |
196 | if (hff_code == hff_decline) return DECLINE; | |
197 | ||
bd4ece7d | 198 | addr->basic_errno = ERRNO_UNKNOWNHOST; |
0756eb3c PH |
199 | addr->message = |
200 | string_sprintf("lookup of host \"%s\" failed in %s router%s", | |
201 | h->name, rblock->name, | |
8768d548 | 202 | f.host_find_failed_syntax? ": syntax error in name" : ""); |
0756eb3c PH |
203 | |
204 | if (hff_code == hff_defer) return DEFER; | |
205 | if (hff_code == hff_fail) return FAIL; | |
206 | ||
207 | addr->special_action = SPECIAL_FREEZE; | |
208 | return DEFER; | |
209 | } | |
210 | ||
fff1b300 EA |
211 | /* Deal with the settings that were previously cleared: |
212 | port, mx and sort_key. */ | |
7cd1141b PH |
213 | |
214 | if (port != PORT_NONE) | |
d7978c0f JH |
215 | for (host_item * hh = h; hh != next_h; hh = hh->next) |
216 | hh->port = port; | |
7cd1141b | 217 | |
fff1b300 | 218 | if (mx != MX_NONE) |
d7978c0f | 219 | for (host_item * hh = h; hh != next_h; hh = hh->next) |
fff1b300 EA |
220 | { |
221 | hh->mx = mx; | |
222 | hh->sort_key = sort_key; | |
223 | } | |
fff1b300 | 224 | |
0756eb3c PH |
225 | /* A local host gets chopped, with its successors, if there are previous |
226 | hosts. Otherwise the self option is used. If it is set to "send", any | |
227 | subsequent hosts that are also the local host do NOT get chopped. */ | |
228 | ||
229 | if (rc == HOST_FOUND_LOCAL && !self_send) | |
230 | { | |
fff1b300 | 231 | if (prev) |
0756eb3c PH |
232 | { |
233 | DEBUG(D_route) | |
234 | { | |
235 | debug_printf("Removed from host list:\n"); | |
56dbf856 | 236 | for (; h; h = h->next) debug_printf(" %s\n", h->name); |
0756eb3c PH |
237 | } |
238 | prev->next = NULL; | |
239 | setflag(addr, af_local_host_removed); | |
240 | break; | |
241 | } | |
242 | rc = rf_self_action(addr, h, rblock->self_code, rblock->self_rewrite, | |
243 | rblock->self, addr_new); | |
244 | if (rc != OK) | |
245 | { | |
246 | addr->host_list = NULL; /* Kill the host list for */ | |
247 | return rc; /* anything other than "send" */ | |
248 | } | |
249 | self_send = TRUE; | |
250 | } | |
cd9868ec PH |
251 | |
252 | /* Ensure that prev is the host before next_h; this will not be h if a lookup | |
253 | found multiple addresses or multiple MX records. */ | |
254 | ||
255 | prev = h; | |
256 | while (prev->next != next_h) prev = prev->next; | |
0756eb3c PH |
257 | } |
258 | ||
259 | return OK; | |
260 | } | |
261 | ||
262 | /* End of rf_lookup_hostlist.c */ |