1 /*	$NetBSD: getnameinfo_verified.c,v 1.1.1.1 2011/04/13 18:15:41 elric Exp $	*/
2 
3 /*
4  * Copyright (c) 1999 - 2002 Kungliga Tekniska Högskolan
5  * (Royal Institute of Technology, Stockholm, Sweden).
6  * All rights reserved.
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  *
15  * 2. Redistributions in binary form must reproduce the above copyright
16  *    notice, this list of conditions and the following disclaimer in the
17  *    documentation and/or other materials provided with the distribution.
18  *
19  * 3. Neither the name of the Institute nor the names of its contributors
20  *    may be used to endorse or promote products derived from this software
21  *    without specific prior written permission.
22  *
23  * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33  * SUCH DAMAGE.
34  */
35 
36 #include <config.h>
37 
38 #include <krb5/roken.h>
39 
40 /*
41  * Try to obtain a verified name for the address in `sa, salen' (much
42  * similar to getnameinfo).
43  * Verified in this context means that forwards and backwards lookups
44  * in DNS are consistent.  If that fails, return an error if the
45  * NI_NAMEREQD flag is set or return the numeric address as a string.
46  */
47 
48 ROKEN_LIB_FUNCTION int ROKEN_LIB_CALL
49 getnameinfo_verified(const struct sockaddr *sa, socklen_t salen,
50 		     char *host, size_t hostlen,
51 		     char *serv, size_t servlen,
52 		     int flags)
53 {
54     int ret;
55     struct addrinfo *ai, *a;
56     char servbuf[NI_MAXSERV];
57     struct addrinfo hints;
58     void *saaddr;
59     size_t sasize;
60 
61     if (host == NULL)
62 	return EAI_NONAME;
63 
64     if (serv == NULL) {
65 	serv = servbuf;
66 	servlen = sizeof(servbuf);
67     }
68 
69     ret = getnameinfo (sa, salen, host, hostlen, serv, servlen,
70 		       flags | NI_NUMERICSERV);
71     if (ret)
72 	goto fail;
73 
74     memset (&hints, 0, sizeof(hints));
75     hints.ai_socktype = SOCK_STREAM;
76     ret = getaddrinfo (host, serv, &hints, &ai);
77     if (ret)
78 	goto fail;
79 
80     saaddr = socket_get_address(sa);
81     sasize = socket_addr_size(sa);
82     for (a = ai; a != NULL; a = a->ai_next) {
83 	if (sasize == socket_addr_size(a->ai_addr) &&
84 	    memcmp(saaddr, socket_get_address(a->ai_addr), sasize) == 0) {
85 	    freeaddrinfo (ai);
86 	    return 0;
87 	}
88     }
89     freeaddrinfo (ai);
90  fail:
91     if (flags & NI_NAMEREQD)
92 	return EAI_NONAME;
93     ret = getnameinfo (sa, salen, host, hostlen, serv, servlen,
94 		       flags | NI_NUMERICSERV | NI_NUMERICHOST);
95     return ret;
96 }
97