realhostname.c revision 56590 
1/*-
2 * Copyright (c) 1999 Brian Somers <brian@Awfulhak.org>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 *
26 * $FreeBSD: head/lib/libutil/realhostname.c 56590 2000-01-25 14:52:10Z shin $
27 */
28
29#include <sys/param.h>
30
31#include <sys/socket.h>
32#include <netdb.h>
33#include <netinet/in.h>
34#include <arpa/inet.h>
35
36#include <stdio.h>
37#include <string.h>
38
39#include "libutil.h"
40
41/* wrapper for KAME-special getnameinfo() */
42#ifndef NI_WITHSCOPEID
43#define	NI_WITHSCOPEID	0
44#endif
45
46struct sockinet {
47	u_char	si_len;
48	u_char	si_family;
49	u_short	si_port;
50};
51
52int
53realhostname(char *host, size_t hsize, const struct in_addr *ip)
54{
55	int result;
56	struct hostent *hp;
57
58	result = HOSTNAME_INVALIDADDR;
59	hp = gethostbyaddr((char *)ip, sizeof(*ip), AF_INET);
60
61	if (hp != NULL && strlen(hp->h_name) <= hsize) {
62		char lookup[MAXHOSTNAMELEN];
63
64		strncpy(lookup, hp->h_name, sizeof(lookup) - 1);
65		lookup[sizeof(lookup) - 1] = '\0';
66		hp = gethostbyname(lookup);
67		if (hp == NULL)
68			result = HOSTNAME_INVALIDNAME;
69		else for (; ; hp->h_addr_list++) {
70			if (hp->h_addr_list[0] == NULL) {
71				result = HOSTNAME_INCORRECTNAME;
72				break;
73			}
74			if (!memcmp(*hp->h_addr_list, ip, sizeof(*ip))) {
75				strncpy(host, lookup, hsize);
76				return HOSTNAME_FOUND;
77			}
78		}
79	}
80
81	strncpy(host, inet_ntoa(*ip), hsize);
82
83	return result;
84}
85
86int
87realhostname_sa(char *host, size_t hsize, struct sockaddr *addr, int addrlen)
88{
89	int result, error;
90
91	result = HOSTNAME_INVALIDADDR;
92
93	error = getnameinfo(addr, addrlen, host, hsize, NULL, 0, 0);
94	if (error == NULL) {
95		struct addrinfo hints, *res, *ores;
96		struct sockaddr *sa;
97
98		memset(&hints, 0, sizeof(struct addrinfo));
99		hints.ai_family = AF_UNSPEC;
100		hints.ai_flags = AI_CANONNAME;
101
102		error = getaddrinfo(host, NULL, &hints, &res);
103		if (error) {
104			result = HOSTNAME_INVALIDNAME;
105			goto numeric;
106		} else for (ores = res; ; res = res->ai_next) {
107			if (res == NULL) {
108				freeaddrinfo(ores);
109				result = HOSTNAME_INCORRECTNAME;
110				goto numeric;
111			}
112			sa = res->ai_addr;
113			if (sa == NULL) {
114				freeaddrinfo(ores);
115				result = HOSTNAME_INCORRECTNAME;
116				goto numeric;
117			}
118			if (sa->sa_len == addrlen &&
119			    sa->sa_family == addr->sa_family) {
120				u_int16_t port;
121
122				port = ((struct sockinet *)addr)->si_port;
123				((struct sockinet *)addr)->si_port = 0;
124				if (!memcmp(sa, addr, sa->sa_len)) {
125					strncpy(host, res->ai_canonname,
126						hsize);
127					result = HOSTNAME_FOUND;
128					((struct sockinet *)addr)->si_port =
129						port;
130					break;
131				}
132				((struct sockinet *)addr)->si_port = port;
133			}
134#ifdef INET6
135			/*
136			 * XXX IPv4 mapped IPv6 addr consideraton,
137			 * specified in rfc2373.
138			 */
139			if (sa->sa_family == AF_INET &&
140			    addr->sa_family == AF_INET6) {
141				struct in_addr *in;
142				struct in6_addr *in6;
143
144				in = &((struct sockaddr_in *)sa)->sin_addr;
145				in6 = &((struct sockaddr_in6 *)addr)->sin6_addr;
146				if (IN6_IS_ADDR_V4MAPPED(in6) &&
147				    !memcmp(&in6->s6_addr[12], in,
148					    sizeof(*in))) {
149					strncpy(host, res->ai_canonname,
150						hsize);
151					result = HOSTNAME_FOUND;
152					break;
153				}
154			}
155#endif
156		}
157		freeaddrinfo(ores);
158	} else {
159    numeric:
160		getnameinfo(addr, addrlen, host, hsize, NULL, 0,
161			    NI_NUMERICHOST|NI_WITHSCOPEID);
162		/* XXX: do 'error' check */
163	}
164
165	return result;
166}
167
168
169