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
27#include <sys/cdefs.h>
28__FBSDID("$FreeBSD: src/lib/libutil/realhostname.c,v 1.18 2005/05/13 16:31:09 ume Exp $");
29
30#include <sys/param.h>
31#include <sys/socket.h>
32
33#include <netdb.h>
34#include <netinet/in.h>
35#include <arpa/inet.h>
36
37#include <stdio.h>
38#include <string.h>
39
40#include "libutil.h"
41
42struct sockinet {
43	u_char	si_len;
44	u_char	si_family;
45	u_short	si_port;
46};
47
48int
49realhostname(char *host, size_t hsize, const struct in_addr *ip)
50{
51	char trimmed[MAXHOSTNAMELEN];
52	int result;
53	struct hostent *hp;
54
55	result = HOSTNAME_INVALIDADDR;
56	hp = gethostbyaddr((const char *)ip, sizeof(*ip), AF_INET);
57
58	if (hp != NULL) {
59		strlcpy(trimmed, hp->h_name, sizeof(trimmed));
60		trimdomain(trimmed, strlen(trimmed));
61		if (strlen(trimmed) <= 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 == NULL) {
71					result = HOSTNAME_INCORRECTNAME;
72					break;
73				}
74				if (!memcmp(*hp->h_addr_list, ip, sizeof(*ip))) {
75					strncpy(host, trimmed, hsize);
76					return HOSTNAME_FOUND;
77				}
78			}
79		}
80	}
81
82	strncpy(host, inet_ntoa(*ip), hsize);
83
84	return result;
85}
86
87int
88realhostname_sa(char *host, size_t hsize, struct sockaddr *addr, int addrlen)
89{
90	int result, error;
91	char buf[NI_MAXHOST];
92#ifdef INET6
93	struct sockaddr_in lsin;
94#endif
95
96	result = HOSTNAME_INVALIDADDR;
97
98#ifdef INET6
99	/* IPv4 mapped IPv6 addr consideraton, specified in rfc2373. */
100	if (addr->sa_family == AF_INET6 &&
101	    addrlen == sizeof(struct sockaddr_in6) &&
102	    IN6_IS_ADDR_V4MAPPED(&((struct sockaddr_in6 *)addr)->sin6_addr)) {
103		struct sockaddr_in6 *sin6;
104
105		sin6 = (struct sockaddr_in6 *)addr;
106
107		memset(&lsin, 0, sizeof(lsin));
108		lsin.sin_len = sizeof(struct sockaddr_in);
109		lsin.sin_family = AF_INET;
110		lsin.sin_port = sin6->sin6_port;
111		memcpy(&lsin.sin_addr, &sin6->sin6_addr.s6_addr[12],
112		       sizeof(struct in_addr));
113		addr = (struct sockaddr *)&lsin;
114		addrlen = lsin.sin_len;
115	}
116#endif
117
118	error = getnameinfo(addr, addrlen, buf, sizeof(buf), NULL, 0,
119			    NI_NAMEREQD);
120	if (error == 0) {
121		struct addrinfo hints, *res, *ores;
122		struct sockaddr *sa;
123
124		memset(&hints, 0, sizeof(struct addrinfo));
125		hints.ai_family = addr->sa_family;
126		hints.ai_flags = AI_CANONNAME | AI_PASSIVE;
127		hints.ai_socktype = SOCK_STREAM;
128
129		error = getaddrinfo(buf, NULL, &hints, &res);
130		if (error) {
131			result = HOSTNAME_INVALIDNAME;
132			goto numeric;
133		}
134		for (ores = res; ; res = res->ai_next) {
135			if (res == NULL) {
136				freeaddrinfo(ores);
137				result = HOSTNAME_INCORRECTNAME;
138				goto numeric;
139			}
140			sa = res->ai_addr;
141			if (sa == NULL) {
142				freeaddrinfo(ores);
143				result = HOSTNAME_INCORRECTNAME;
144				goto numeric;
145			}
146			if (sa->sa_len == addrlen &&
147			    sa->sa_family == addr->sa_family) {
148				((struct sockinet *)sa)->si_port = ((struct sockinet *)addr)->si_port;
149#ifdef INET6
150				/*
151				 * XXX: sin6_socpe_id may not been
152				 * filled by DNS
153				 */
154				if (sa->sa_family == AF_INET6 &&
155				    ((struct sockaddr_in6 *)sa)->sin6_scope_id == 0)
156					((struct sockaddr_in6 *)sa)->sin6_scope_id = ((struct sockaddr_in6 *)addr)->sin6_scope_id;
157#endif
158				if (!memcmp(sa, addr, sa->sa_len)) {
159					result = HOSTNAME_FOUND;
160					if (ores->ai_canonname == NULL) {
161						freeaddrinfo(ores);
162						goto numeric;
163					}
164					strlcpy(buf, ores->ai_canonname,
165						sizeof(buf));
166					trimdomain(buf, hsize);
167					if (strlen(buf) > hsize &&
168					    addr->sa_family == AF_INET) {
169						freeaddrinfo(ores);
170						goto numeric;
171					}
172					strncpy(host, buf, hsize);
173					break;
174				}
175			}
176		}
177		freeaddrinfo(ores);
178	} else {
179    numeric:
180		if (getnameinfo(addr, addrlen, buf, sizeof(buf), NULL, 0,
181				NI_NUMERICHOST) == 0)
182			strncpy(host, buf, hsize);
183	}
184
185	return result;
186}
187
188
189