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8cbdbd34 | 1 | /* |
e458e5f0 | 2 | * Copyright (c) 2008-2014, Simon Schubert <2@0x2c.org>. |
8cbdbd34 SS |
3 | * Copyright (c) 2008 The DragonFly Project. All rights reserved. |
4 | * | |
5 | * This code is derived from software contributed to The DragonFly Project | |
e458e5f0 | 6 | * by Simon Schubert <2@0x2c.org>. |
8cbdbd34 SS |
7 | * |
8 | * Redistribution and use in source and binary forms, with or without | |
9 | * modification, are permitted provided that the following conditions | |
10 | * are met: | |
11 | * | |
12 | * 1. Redistributions of source code must retain the above copyright | |
13 | * notice, this list of conditions and the following disclaimer. | |
14 | * 2. Redistributions in binary form must reproduce the above copyright | |
15 | * notice, this list of conditions and the following disclaimer in | |
16 | * the documentation and/or other materials provided with the | |
17 | * distribution. | |
18 | * 3. Neither the name of The DragonFly Project nor the names of its | |
19 | * contributors may be used to endorse or promote products derived | |
20 | * from this software without specific, prior written permission. | |
21 | * | |
22 | * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS | |
23 | * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT | |
24 | * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS | |
25 | * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE | |
26 | * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, | |
27 | * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING, | |
28 | * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; | |
29 | * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED | |
30 | * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, | |
31 | * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT | |
32 | * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF | |
33 | * SUCH DAMAGE. | |
34 | */ | |
35 | ||
36 | #include <sys/types.h> | |
00077282 | 37 | #include <sys/param.h> |
8cbdbd34 SS |
38 | #include <netinet/in.h> |
39 | #include <arpa/inet.h> | |
40 | #include <arpa/nameser.h> | |
41 | #include <errno.h> | |
42 | #include <netdb.h> | |
43 | #include <resolv.h> | |
44 | #include <string.h> | |
45 | #include <stdlib.h> | |
46 | ||
47 | #include "dma.h" | |
48 | ||
49 | static int | |
50 | sort_pref(const void *a, const void *b) | |
51 | { | |
52 | const struct mx_hostentry *ha = a, *hb = b; | |
53 | int v; | |
54 | ||
55 | /* sort increasing by preference primarily */ | |
56 | v = ha->pref - hb->pref; | |
57 | if (v != 0) | |
58 | return (v); | |
59 | ||
60 | /* sort PF_INET6 before PF_INET */ | |
61 | v = - (ha->ai.ai_family - hb->ai.ai_family); | |
62 | return (v); | |
63 | } | |
64 | ||
65 | static int | |
66 | add_host(int pref, const char *host, int port, struct mx_hostentry **he, size_t *ps) | |
67 | { | |
68 | struct addrinfo hints, *res, *res0 = NULL; | |
69 | char servname[10]; | |
70 | struct mx_hostentry *p; | |
8cbdbd34 | 71 | const int count_inc = 10; |
8cbdbd34 | 72 | |
8cbdbd34 SS |
73 | memset(&hints, 0, sizeof(hints)); |
74 | hints.ai_family = PF_UNSPEC; | |
75 | hints.ai_socktype = SOCK_STREAM; | |
76 | hints.ai_protocol = IPPROTO_TCP; | |
77 | ||
78 | snprintf(servname, sizeof(servname), "%d", port); | |
1a1306df AS |
79 | switch (getaddrinfo(host, servname, &hints, &res0)) { |
80 | case 0: | |
81 | break; | |
82 | case EAI_AGAIN: | |
83 | case EAI_NONAME: | |
84 | /* | |
85 | * EAI_NONAME gets returned for: | |
86 | * SMARTHOST set but DNS server not reachable -> defer | |
87 | * SMARTHOST set but DNS server returns "host does not exist" | |
88 | * -> buggy configuration | |
89 | * -> either defer or bounce would be ok -> defer | |
90 | * MX entry was returned by DNS server but name doesn't resolve | |
91 | * -> hopefully transient situation -> defer | |
92 | * all other DNS problems should have been caught earlier | |
93 | * in dns_get_mx_list(). | |
94 | */ | |
95 | goto out; | |
96 | default: | |
97 | return(-1); | |
98 | } | |
8cbdbd34 SS |
99 | |
100 | for (res = res0; res != NULL; res = res->ai_next) { | |
101 | if (*ps + 1 >= roundup(*ps, count_inc)) { | |
102 | size_t newsz = roundup(*ps + 2, count_inc); | |
103 | *he = reallocf(*he, newsz * sizeof(**he)); | |
104 | if (*he == NULL) | |
105 | goto out; | |
106 | } | |
107 | ||
108 | p = &(*he)[*ps]; | |
109 | strlcpy(p->host, host, sizeof(p->host)); | |
110 | p->pref = pref; | |
111 | p->ai = *res; | |
112 | p->ai.ai_addr = NULL; | |
113 | bcopy(res->ai_addr, &p->sa, p->ai.ai_addrlen); | |
114 | ||
32d3ec65 | 115 | getnameinfo((struct sockaddr *)&p->sa, p->ai.ai_addrlen, |
8cbdbd34 SS |
116 | p->addr, sizeof(p->addr), |
117 | NULL, 0, NI_NUMERICHOST); | |
118 | ||
119 | (*ps)++; | |
120 | } | |
121 | freeaddrinfo(res0); | |
122 | ||
06dd5b89 | 123 | return (0); |
8cbdbd34 SS |
124 | |
125 | out: | |
126 | if (res0 != NULL) | |
127 | freeaddrinfo(res0); | |
4b26e6a7 | 128 | return (1); |
8cbdbd34 SS |
129 | } |
130 | ||
131 | int | |
132 | dns_get_mx_list(const char *host, int port, struct mx_hostentry **he, int no_mx) | |
133 | { | |
134 | char outname[MAXDNAME]; | |
135 | ns_msg msg; | |
136 | ns_rr rr; | |
137 | const char *searchhost; | |
9b921550 SS |
138 | const unsigned char *cp; |
139 | unsigned char *ans; | |
8cbdbd34 SS |
140 | struct mx_hostentry *hosts = NULL; |
141 | size_t nhosts = 0; | |
142 | size_t anssz; | |
143 | int pref; | |
144 | int cname_recurse; | |
4b26e6a7 | 145 | int have_mx = 0; |
8cbdbd34 SS |
146 | int err; |
147 | int i; | |
148 | ||
149 | res_init(); | |
150 | searchhost = host; | |
151 | cname_recurse = 0; | |
152 | ||
153 | anssz = 65536; | |
154 | ans = malloc(anssz); | |
155 | if (ans == NULL) | |
156 | return (1); | |
157 | ||
158 | if (no_mx) | |
159 | goto out; | |
160 | ||
161 | repeat: | |
162 | err = res_search(searchhost, ns_c_in, ns_t_mx, ans, anssz); | |
163 | if (err < 0) { | |
164 | switch (h_errno) { | |
165 | case NO_DATA: | |
166 | /* | |
167 | * Host exists, but no MX (or CNAME) entry. | |
168 | * Not an error, use host name instead. | |
169 | */ | |
170 | goto out; | |
171 | case TRY_AGAIN: | |
172 | /* transient error */ | |
173 | goto transerr; | |
174 | case NO_RECOVERY: | |
175 | case HOST_NOT_FOUND: | |
176 | default: | |
177 | errno = ENOENT; | |
178 | goto err; | |
179 | } | |
180 | } | |
181 | ||
182 | if (!ns_initparse(ans, anssz, &msg)) | |
183 | goto transerr; | |
184 | ||
185 | switch (ns_msg_getflag(msg, ns_f_rcode)) { | |
186 | case ns_r_noerror: | |
187 | break; | |
188 | case ns_r_nxdomain: | |
189 | goto err; | |
190 | default: | |
191 | goto transerr; | |
192 | } | |
193 | ||
194 | for (i = 0; i < ns_msg_count(msg, ns_s_an); i++) { | |
195 | if (ns_parserr(&msg, ns_s_an, i, &rr)) | |
196 | goto transerr; | |
197 | ||
9b921550 | 198 | cp = ns_rr_rdata(rr); |
8cbdbd34 SS |
199 | |
200 | switch (ns_rr_type(rr)) { | |
201 | case ns_t_mx: | |
4b26e6a7 | 202 | have_mx = 1; |
8cbdbd34 SS |
203 | pref = ns_get16(cp); |
204 | cp += 2; | |
205 | err = ns_name_uncompress(ns_msg_base(msg), ns_msg_end(msg), | |
206 | cp, outname, sizeof(outname)); | |
207 | if (err < 0) | |
208 | goto transerr; | |
209 | ||
4b26e6a7 SS |
210 | err = add_host(pref, outname, port, &hosts, &nhosts); |
211 | if (err == -1) | |
212 | goto err; | |
8cbdbd34 SS |
213 | break; |
214 | ||
215 | case ns_t_cname: | |
216 | err = ns_name_uncompress(ns_msg_base(msg), ns_msg_end(msg), | |
217 | cp, outname, sizeof(outname)); | |
218 | if (err < 0) | |
219 | goto transerr; | |
220 | ||
221 | /* Prevent a CNAME loop */ | |
222 | if (cname_recurse++ > 10) | |
223 | goto err; | |
224 | ||
225 | searchhost = outname; | |
226 | goto repeat; | |
227 | ||
228 | default: | |
229 | break; | |
230 | } | |
231 | } | |
232 | ||
233 | out: | |
234 | err = 0; | |
235 | if (0) { | |
236 | transerr: | |
237 | if (nhosts == 0) | |
238 | err = 1; | |
239 | } | |
240 | if (0) { | |
241 | err: | |
242 | err = -1; | |
243 | } | |
244 | ||
245 | free(ans); | |
246 | ||
4b26e6a7 SS |
247 | if (err == 0) { |
248 | if (!have_mx) { | |
249 | /* | |
250 | * If we didn't find any MX, use the hostname instead. | |
251 | */ | |
252 | err = add_host(0, host, port, &hosts, &nhosts); | |
253 | } else if (nhosts == 0) { | |
254 | /* | |
255 | * We did get MX, but couldn't resolve any of them | |
256 | * due to transient errors. | |
257 | */ | |
258 | err = 1; | |
259 | } | |
8cbdbd34 SS |
260 | } |
261 | ||
262 | if (nhosts > 0) { | |
4b26e6a7 | 263 | qsort(hosts, nhosts, sizeof(*hosts), sort_pref); |
8cbdbd34 SS |
264 | /* terminate list */ |
265 | *hosts[nhosts].host = 0; | |
266 | } else { | |
267 | if (hosts != NULL) | |
268 | free(hosts); | |
269 | hosts = NULL; | |
270 | } | |
271 | ||
272 | *he = hosts; | |
273 | return (err); | |
274 | ||
275 | free(ans); | |
276 | if (hosts != NULL) | |
277 | free(hosts); | |
278 | return (err); | |
279 | } | |
280 | ||
281 | #if defined(TESTING) | |
282 | int | |
283 | main(int argc, char **argv) | |
284 | { | |
285 | struct mx_hostentry *he, *p; | |
286 | int err; | |
287 | ||
288 | err = dns_get_mx_list(argv[1], 53, &he, 0); | |
289 | if (err) | |
290 | return (err); | |
291 | ||
292 | for (p = he; *p->host != 0; p++) { | |
293 | printf("%d\t%s\t%s\n", p->pref, p->host, p->addr); | |
294 | } | |
295 | ||
296 | return (0); | |
297 | } | |
298 | #endif |