1/*	$NetBSD: getnameinfo_verified.c,v 1.2 2017/01/28 21:31:50 christos Exp $	*/
2
3/*
4 * Copyright (c) 1999 - 2002 Kungliga Tekniska H��gskolan
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
48ROKEN_LIB_FUNCTION int ROKEN_LIB_CALL
49getnameinfo_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