realhostname.c revision 98021 
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: head/lib/libutil/realhostname.c 98021 2002-06-07 17:25:19Z ume $");
29
30#include <sys/param.h>
31
32#include <sys/socket.h>
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
42/* wrapper for KAME-special getnameinfo() */
43#ifndef NI_WITHSCOPEID
44#define	NI_WITHSCOPEID	0
45#endif
46
47struct sockinet {
48	u_char	si_len;
49	u_char	si_family;
50	u_short	si_port;
51};
52
53int
54realhostname(char *host, size_t hsize, const struct in_addr *ip)
55{
56	char trimmed[MAXHOSTNAMELEN];
57	int result;
58	struct hostent *hp;
59
60	result = HOSTNAME_INVALIDADDR;
61	hp = gethostbyaddr((char *)ip, sizeof(*ip), AF_INET);
62
63	if (hp != NULL) {
64		strlcpy(trimmed, hp->h_name, sizeof(trimmed));
65		trimdomain(trimmed, strlen(trimmed));
66		if (strlen(trimmed) <= hsize) {
67			char lookup[MAXHOSTNAMELEN];
68
69			strncpy(lookup, hp->h_name, sizeof(lookup) - 1);
70			lookup[sizeof(lookup) - 1] = '\0';
71			hp = gethostbyname(lookup);
72			if (hp == NULL)
73				result = HOSTNAME_INVALIDNAME;
74			else for (; ; hp->h_addr_list++) {
75				if (*hp->h_addr_list == NULL) {
76					result = HOSTNAME_INCORRECTNAME;
77					break;
78				}
79				if (!memcmp(*hp->h_addr_list, ip, sizeof(*ip))) {
80					strncpy(host, trimmed, hsize);
81					return HOSTNAME_FOUND;
82				}
83			}
84		}
85	}
86
87	strncpy(host, inet_ntoa(*ip), hsize);
88
89	return result;
90}
91
92int
93realhostname_sa(char *host, size_t hsize, struct sockaddr *addr, int addrlen)
94{
95	int result, error;
96	char buf[NI_MAXHOST];
97	struct sockaddr_in sin;
98
99	result = HOSTNAME_INVALIDADDR;
100
101#ifdef INET6
102	/* IPv4 mapped IPv6 addr consideraton, specified in rfc2373. */
103	if (addr->sa_family == AF_INET6 &&
104	    addrlen == sizeof(struct sockaddr_in6) &&
105	    IN6_IS_ADDR_V4MAPPED(&((struct sockaddr_in6 *)addr)->sin6_addr)) {
106		struct sockaddr_in6 *sin6;
107
108		sin6 = (struct sockaddr_in6 *)addr;
109
110		memset(&sin, 0, sizeof(sin));
111		sin.sin_len = sizeof(struct sockaddr_in);
112		sin.sin_family = AF_INET;
113		sin.sin_port = sin6->sin6_port;
114		memcpy(&sin.sin_addr, &sin6->sin6_addr.s6_addr[12],
115		       sizeof(struct in_addr));
116		addr = (struct sockaddr *)&sin;
117		addrlen = sin.sin_len;
118	}
119#endif
120
121	error = getnameinfo(addr, addrlen, buf, sizeof(buf), NULL, 0,
122			    NI_WITHSCOPEID | NI_NAMEREQD);
123	if (error == 0) {
124		struct addrinfo hints, *res, *ores;
125		struct sockaddr *sa;
126
127		memset(&hints, 0, sizeof(struct addrinfo));
128		hints.ai_family = addr->sa_family;
129		hints.ai_flags = AI_CANONNAME | AI_PASSIVE;
130		hints.ai_socktype = SOCK_STREAM;
131
132		error = getaddrinfo(buf, NULL, &hints, &res);
133		if (error) {
134			result = HOSTNAME_INVALIDNAME;
135			goto numeric;
136		}
137		for (ores = res; ; res = res->ai_next) {
138			if (res == NULL) {
139				freeaddrinfo(ores);
140				result = HOSTNAME_INCORRECTNAME;
141				goto numeric;
142			}
143			sa = res->ai_addr;
144			if (sa == NULL) {
145				freeaddrinfo(ores);
146				result = HOSTNAME_INCORRECTNAME;
147				goto numeric;
148			}
149			if (sa->sa_len == addrlen &&
150			    sa->sa_family == addr->sa_family) {
151				((struct sockinet *)sa)->si_port = ((struct sockinet *)addr)->si_port;
152#ifdef INET6
153				/*
154				 * XXX: sin6_socpe_id may not been
155				 * filled by DNS
156				 */
157				if (sa->sa_family == AF_INET6 &&
158				    ((struct sockaddr_in6 *)sa)->sin6_scope_id == 0)
159					((struct sockaddr_in6 *)sa)->sin6_scope_id = ((struct sockaddr_in6 *)addr)->sin6_scope_id;
160#endif
161				if (!memcmp(sa, addr, sa->sa_len)) {
162					result = HOSTNAME_FOUND;
163					if (ores->ai_canonname == NULL) {
164						freeaddrinfo(ores);
165						goto numeric;
166					}
167					strlcpy(buf, ores->ai_canonname,
168						sizeof(buf));
169					trimdomain(buf, hsize);
170					if (strlen(buf) > hsize &&
171					    addr->sa_family == AF_INET) {
172						freeaddrinfo(ores);
173						goto numeric;
174					}
175					strncpy(host, buf, hsize);
176					break;
177				}
178			}
179		}
180		freeaddrinfo(ores);
181	} else {
182    numeric:
183		if (getnameinfo(addr, addrlen, buf, sizeof(buf), NULL, 0,
184				NI_NUMERICHOST|NI_WITHSCOPEID) == 0)
185			strncpy(host, buf, hsize);
186	}
187
188	return result;
189}
190
191
192