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
29#include <sys/param.h>
30#include <sys/socket.h>
31
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
41struct sockinet {
42	u_char	si_len;
43	u_char	si_family;
44	u_short	si_port;
45};
46
47void trimdomain(char *_fullhost, size_t _hostsize);
48
49int
50realhostname(char *host, size_t hsize, const struct in_addr *ip)
51{
52	char trimmed[MAXHOSTNAMELEN];
53	int result;
54	struct hostent *hp;
55
56	result = HOSTNAME_INVALIDADDR;
57	hp = gethostbyaddr((const char *)ip, sizeof(*ip), AF_INET);
58
59	if (hp != NULL) {
60		strlcpy(trimmed, hp->h_name, sizeof(trimmed));
61		trimdomain(trimmed, strlen(trimmed));
62		if (strlen(trimmed) <= hsize) {
63			char lookup[MAXHOSTNAMELEN];
64
65			strncpy(lookup, hp->h_name, sizeof(lookup) - 1);
66			lookup[sizeof(lookup) - 1] = '\0';
67			hp = gethostbyname(lookup);
68			if (hp == NULL)
69				result = HOSTNAME_INVALIDNAME;
70			else for (; ; hp->h_addr_list++) {
71				if (*hp->h_addr_list == NULL) {
72					result = HOSTNAME_INCORRECTNAME;
73					break;
74				}
75				if (!memcmp(*hp->h_addr_list, ip, sizeof(*ip))) {
76					strncpy(host, trimmed, hsize);
77					return HOSTNAME_FOUND;
78				}
79			}
80		}
81	}
82
83	strncpy(host, inet_ntoa(*ip), hsize);
84
85	return result;
86}
87
88int
89realhostname_sa(char *host, size_t hsize, struct sockaddr *addr, int addrlen)
90{
91	int result, error;
92	char buf[NI_MAXHOST];
93
94	result = HOSTNAME_INVALIDADDR;
95
96#ifdef INET6
97	/* IPv4 mapped IPv6 addr consideraton, specified in rfc2373. */
98	if (addr->sa_family == AF_INET6 &&
99	    addrlen == sizeof(struct sockaddr_in6) &&
100	    IN6_IS_ADDR_V4MAPPED(&((struct sockaddr_in6 *)addr)->sin6_addr)) {
101		struct sockaddr_in6 *sin6;
102
103		sin6 = (struct sockaddr_in6 *)addr;
104
105		memset(&lsin, 0, sizeof(lsin));
106		lsin.sin_len = sizeof(struct sockaddr_in);
107		lsin.sin_family = AF_INET;
108		lsin.sin_port = sin6->sin6_port;
109		memcpy(&lsin.sin_addr, &sin6->sin6_addr.s6_addr[12],
110		       sizeof(struct in_addr));
111		addr = (struct sockaddr *)&lsin;
112		addrlen = lsin.sin_len;
113	}
114#endif
115
116	error = getnameinfo(addr, addrlen, buf, sizeof(buf), NULL, 0,
117			    NI_NAMEREQD);
118	if (error == 0) {
119		struct addrinfo hints, *res, *ores;
120		struct sockaddr *sa;
121
122		memset(&hints, 0, sizeof(struct addrinfo));
123		hints.ai_family = addr->sa_family;
124		hints.ai_flags = AI_CANONNAME | AI_PASSIVE;
125		hints.ai_socktype = SOCK_STREAM;
126
127		error = getaddrinfo(buf, NULL, &hints, &res);
128		if (error) {
129			result = HOSTNAME_INVALIDNAME;
130			goto numeric;
131		}
132		for (ores = res; ; res = res->ai_next) {
133			if (res == NULL) {
134				freeaddrinfo(ores);
135				result = HOSTNAME_INCORRECTNAME;
136				goto numeric;
137			}
138			sa = res->ai_addr;
139			if (sa == NULL) {
140				freeaddrinfo(ores);
141				result = HOSTNAME_INCORRECTNAME;
142				goto numeric;
143			}
144			if (sa->sa_len == addrlen &&
145			    sa->sa_family == addr->sa_family) {
146				((struct sockinet *)sa)->si_port = ((struct sockinet *)addr)->si_port;
147#ifdef INET6
148				/*
149				 * XXX: sin6_socpe_id may not been
150				 * filled by DNS
151				 */
152				if (sa->sa_family == AF_INET6 &&
153				    ((struct sockaddr_in6 *)sa)->sin6_scope_id == 0)
154					((struct sockaddr_in6 *)sa)->sin6_scope_id = ((struct sockaddr_in6 *)addr)->sin6_scope_id;
155#endif
156				if (!memcmp(sa, addr, sa->sa_len)) {
157					result = HOSTNAME_FOUND;
158					if (ores->ai_canonname == NULL) {
159						freeaddrinfo(ores);
160						goto numeric;
161					}
162					strlcpy(buf, ores->ai_canonname,
163						sizeof(buf));
164					trimdomain(buf, hsize);
165					if (strlen(buf) > hsize &&
166					    addr->sa_family == AF_INET) {
167						freeaddrinfo(ores);
168						goto numeric;
169					}
170					strncpy(host, buf, hsize);
171					break;
172				}
173			}
174		}
175		freeaddrinfo(ores);
176	} else {
177    numeric:
178		if (getnameinfo(addr, addrlen, buf, sizeof(buf), NULL, 0,
179				NI_NUMERICHOST) == 0)
180			strncpy(host, buf, hsize);
181	}
182
183	return result;
184}
185
186
187