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