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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; | |
69 | size_t onhosts; | |
70 | const int count_inc = 10; | |
71 | int err; | |
72 | ||
73 | onhosts = *ps; | |
74 | ||
75 | memset(&hints, 0, sizeof(hints)); | |
76 | hints.ai_family = PF_UNSPEC; | |
77 | hints.ai_socktype = SOCK_STREAM; | |
78 | hints.ai_protocol = IPPROTO_TCP; | |
79 | ||
80 | snprintf(servname, sizeof(servname), "%d", port); | |
81 | err = getaddrinfo(host, servname, &hints, &res0); | |
82 | if (err) | |
83 | return (-1); | |
84 | ||
85 | for (res = res0; res != NULL; res = res->ai_next) { | |
86 | if (*ps + 1 >= roundup(*ps, count_inc)) { | |
87 | size_t newsz = roundup(*ps + 2, count_inc); | |
88 | *he = reallocf(*he, newsz * sizeof(**he)); | |
89 | if (*he == NULL) | |
90 | goto out; | |
91 | } | |
92 | ||
93 | p = &(*he)[*ps]; | |
94 | strlcpy(p->host, host, sizeof(p->host)); | |
95 | p->pref = pref; | |
96 | p->ai = *res; | |
97 | p->ai.ai_addr = NULL; | |
98 | bcopy(res->ai_addr, &p->sa, p->ai.ai_addrlen); | |
99 | ||
32d3ec65 | 100 | getnameinfo((struct sockaddr *)&p->sa, p->ai.ai_addrlen, |
8cbdbd34 SS |
101 | p->addr, sizeof(p->addr), |
102 | NULL, 0, NI_NUMERICHOST); | |
103 | ||
104 | (*ps)++; | |
105 | } | |
106 | freeaddrinfo(res0); | |
107 | ||
108 | return (*ps - onhosts); | |
109 | ||
110 | out: | |
111 | if (res0 != NULL) | |
112 | freeaddrinfo(res0); | |
113 | return (-1); | |
114 | } | |
115 | ||
116 | int | |
117 | dns_get_mx_list(const char *host, int port, struct mx_hostentry **he, int no_mx) | |
118 | { | |
119 | char outname[MAXDNAME]; | |
120 | ns_msg msg; | |
121 | ns_rr rr; | |
122 | const char *searchhost; | |
9b921550 SS |
123 | const unsigned char *cp; |
124 | unsigned char *ans; | |
8cbdbd34 SS |
125 | struct mx_hostentry *hosts = NULL; |
126 | size_t nhosts = 0; | |
127 | size_t anssz; | |
128 | int pref; | |
129 | int cname_recurse; | |
130 | int err; | |
131 | int i; | |
132 | ||
133 | res_init(); | |
134 | searchhost = host; | |
135 | cname_recurse = 0; | |
136 | ||
137 | anssz = 65536; | |
138 | ans = malloc(anssz); | |
139 | if (ans == NULL) | |
140 | return (1); | |
141 | ||
142 | if (no_mx) | |
143 | goto out; | |
144 | ||
145 | repeat: | |
146 | err = res_search(searchhost, ns_c_in, ns_t_mx, ans, anssz); | |
147 | if (err < 0) { | |
148 | switch (h_errno) { | |
149 | case NO_DATA: | |
150 | /* | |
151 | * Host exists, but no MX (or CNAME) entry. | |
152 | * Not an error, use host name instead. | |
153 | */ | |
154 | goto out; | |
155 | case TRY_AGAIN: | |
156 | /* transient error */ | |
157 | goto transerr; | |
158 | case NO_RECOVERY: | |
159 | case HOST_NOT_FOUND: | |
160 | default: | |
161 | errno = ENOENT; | |
162 | goto err; | |
163 | } | |
164 | } | |
165 | ||
166 | if (!ns_initparse(ans, anssz, &msg)) | |
167 | goto transerr; | |
168 | ||
169 | switch (ns_msg_getflag(msg, ns_f_rcode)) { | |
170 | case ns_r_noerror: | |
171 | break; | |
172 | case ns_r_nxdomain: | |
173 | goto err; | |
174 | default: | |
175 | goto transerr; | |
176 | } | |
177 | ||
178 | for (i = 0; i < ns_msg_count(msg, ns_s_an); i++) { | |
179 | if (ns_parserr(&msg, ns_s_an, i, &rr)) | |
180 | goto transerr; | |
181 | ||
9b921550 | 182 | cp = ns_rr_rdata(rr); |
8cbdbd34 SS |
183 | |
184 | switch (ns_rr_type(rr)) { | |
185 | case ns_t_mx: | |
186 | pref = ns_get16(cp); | |
187 | cp += 2; | |
188 | err = ns_name_uncompress(ns_msg_base(msg), ns_msg_end(msg), | |
189 | cp, outname, sizeof(outname)); | |
190 | if (err < 0) | |
191 | goto transerr; | |
192 | ||
193 | add_host(pref, outname, port, &hosts, &nhosts); | |
194 | break; | |
195 | ||
196 | case ns_t_cname: | |
197 | err = ns_name_uncompress(ns_msg_base(msg), ns_msg_end(msg), | |
198 | cp, outname, sizeof(outname)); | |
199 | if (err < 0) | |
200 | goto transerr; | |
201 | ||
202 | /* Prevent a CNAME loop */ | |
203 | if (cname_recurse++ > 10) | |
204 | goto err; | |
205 | ||
206 | searchhost = outname; | |
207 | goto repeat; | |
208 | ||
209 | default: | |
210 | break; | |
211 | } | |
212 | } | |
213 | ||
214 | out: | |
215 | err = 0; | |
216 | if (0) { | |
217 | transerr: | |
218 | if (nhosts == 0) | |
219 | err = 1; | |
220 | } | |
221 | if (0) { | |
222 | err: | |
223 | err = -1; | |
224 | } | |
225 | ||
226 | free(ans); | |
227 | ||
228 | if (!err) { | |
229 | /* | |
230 | * If we didn't find any MX, use the hostname instead. | |
231 | */ | |
232 | if (nhosts == 0) | |
233 | add_host(0, searchhost, port, &hosts, &nhosts); | |
234 | ||
235 | qsort(hosts, nhosts, sizeof(*hosts), sort_pref); | |
236 | } | |
237 | ||
238 | if (nhosts > 0) { | |
239 | /* terminate list */ | |
240 | *hosts[nhosts].host = 0; | |
241 | } else { | |
242 | if (hosts != NULL) | |
243 | free(hosts); | |
244 | hosts = NULL; | |
245 | } | |
246 | ||
247 | *he = hosts; | |
248 | return (err); | |
249 | ||
250 | free(ans); | |
251 | if (hosts != NULL) | |
252 | free(hosts); | |
253 | return (err); | |
254 | } | |
255 | ||
256 | #if defined(TESTING) | |
257 | int | |
258 | main(int argc, char **argv) | |
259 | { | |
260 | struct mx_hostentry *he, *p; | |
261 | int err; | |
262 | ||
263 | err = dns_get_mx_list(argv[1], 53, &he, 0); | |
264 | if (err) | |
265 | return (err); | |
266 | ||
267 | for (p = he; *p->host != 0; p++) { | |
268 | printf("%d\t%s\t%s\n", p->pref, p->host, p->addr); | |
269 | } | |
270 | ||
271 | return (0); | |
272 | } | |
273 | #endif |