2 * Copyright (c) 2008 The DragonFly Project. All rights reserved.
4 * This code is derived from software contributed to The DragonFly Project
5 * by Simon 'corecode' Schubert <corecode@fs.ei.tum.de>
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
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
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.
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
35 #include <sys/types.h>
36 #include <netinet/in.h>
37 #include <arpa/inet.h>
38 #include <arpa/nameser.h>
48 sort_pref(const void *a
, const void *b
)
50 const struct mx_hostentry
*ha
= a
, *hb
= b
;
53 /* sort increasing by preference primarily */
54 v
= ha
->pref
- hb
->pref
;
58 /* sort PF_INET6 before PF_INET */
59 v
= - (ha
->ai
.ai_family
- hb
->ai
.ai_family
);
64 add_host(int pref
, const char *host
, int port
, struct mx_hostentry
**he
, size_t *ps
)
66 struct addrinfo hints
, *res
, *res0
= NULL
;
68 struct mx_hostentry
*p
;
70 const int count_inc
= 10;
75 memset(&hints
, 0, sizeof(hints
));
76 hints
.ai_family
= PF_UNSPEC
;
77 hints
.ai_socktype
= SOCK_STREAM
;
78 hints
.ai_protocol
= IPPROTO_TCP
;
80 snprintf(servname
, sizeof(servname
), "%d", port
);
81 err
= getaddrinfo(host
, servname
, &hints
, &res0
);
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
));
94 strlcpy(p
->host
, host
, sizeof(p
->host
));
98 bcopy(res
->ai_addr
, &p
->sa
, p
->ai
.ai_addrlen
);
100 getnameinfo((struct sockaddr
*)&p
->sa
, p
->ai
.ai_addrlen
,
101 p
->addr
, sizeof(p
->addr
),
102 NULL
, 0, NI_NUMERICHOST
);
108 return (*ps
- onhosts
);
117 dns_get_mx_list(const char *host
, int port
, struct mx_hostentry
**he
, int no_mx
)
119 char outname
[MAXDNAME
];
122 const char *searchhost
;
125 struct mx_hostentry
*hosts
= NULL
;
146 err
= res_search(searchhost
, ns_c_in
, ns_t_mx
, ans
, anssz
);
151 * Host exists, but no MX (or CNAME) entry.
152 * Not an error, use host name instead.
156 /* transient error */
166 if (!ns_initparse(ans
, anssz
, &msg
))
169 switch (ns_msg_getflag(msg
, ns_f_rcode
)) {
178 for (i
= 0; i
< ns_msg_count(msg
, ns_s_an
); i
++) {
179 if (ns_parserr(&msg
, ns_s_an
, i
, &rr
))
182 cp
= (const char *)ns_rr_rdata(rr
);
184 switch (ns_rr_type(rr
)) {
188 err
= ns_name_uncompress(ns_msg_base(msg
), ns_msg_end(msg
),
189 cp
, outname
, sizeof(outname
));
193 add_host(pref
, outname
, port
, &hosts
, &nhosts
);
197 err
= ns_name_uncompress(ns_msg_base(msg
), ns_msg_end(msg
),
198 cp
, outname
, sizeof(outname
));
202 /* Prevent a CNAME loop */
203 if (cname_recurse
++ > 10)
206 searchhost
= outname
;
230 * If we didn't find any MX, use the hostname instead.
233 add_host(0, searchhost
, port
, &hosts
, &nhosts
);
235 qsort(hosts
, nhosts
, sizeof(*hosts
), sort_pref
);
240 *hosts
[nhosts
].host
= 0;
258 main(int argc
, char **argv
)
260 struct mx_hostentry
*he
, *p
;
263 err
= dns_get_mx_list(argv
[1], 53, &he
, 0);
267 for (p
= he
; *p
->host
!= 0; p
++) {
268 printf("%d\t%s\t%s\n", p
->pref
, p
->host
, p
->addr
);