realhostname.c revision 80223 
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 80223 2001-07-23 21:42:22Z ume $
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	char trimmed[MAXHOSTNAMELEN];
56	int result;
57	struct hostent *hp;
58
59	result = HOSTNAME_INVALIDADDR;
60	hp = gethostbyaddr((char *)ip, sizeof(*ip), AF_INET);
61
62	if (hp != NULL) {
63		strlcpy(trimmed, hp->h_name, sizeof(trimmed));
64		trimdomain(trimmed, strlen(trimmed));
65		if (strlen(trimmed) <= hsize) {
66			char lookup[MAXHOSTNAMELEN];
67
68			strncpy(lookup, hp->h_name, sizeof(lookup) - 1);
69			lookup[sizeof(lookup) - 1] = '\0';
70			hp = gethostbyname(lookup);
71			if (hp == NULL)
72				result = HOSTNAME_INVALIDNAME;
73			else for (; ; hp->h_addr_list++) {
74				if (*hp->h_addr_list == NULL) {
75					result = HOSTNAME_INCORRECTNAME;
76					break;
77				}
78				if (!memcmp(*hp->h_addr_list, ip, sizeof(*ip))) {
79					strncpy(host, trimmed, hsize);
80					return HOSTNAME_FOUND;
81				}
82			}
83		}
84	}
85
86	strncpy(host, inet_ntoa(*ip), hsize);
87
88	return result;
89}
90
91int
92realhostname_sa(char *host, size_t hsize, struct sockaddr *addr, int addrlen)
93{
94	int result, error;
95	char buf[NI_MAXHOST];
96	struct sockaddr_in sin;
97
98	result = HOSTNAME_INVALIDADDR;
99
100#ifdef INET6
101	/* IPv4 mapped IPv6 addr consideraton, specified in rfc2373. */
102	if (addr->sa_family == AF_INET6 &&
103	    addrlen == sizeof(struct sockaddr_in6) &&
104	    IN6_IS_ADDR_V4MAPPED(&((struct sockaddr_in6 *)addr)->sin6_addr)) {
105		struct sockaddr_in6 *sin6;
106
107		sin6 = (struct sockaddr_in6 *)addr;
108
109		memset(&sin, 0, sizeof(sin));
110		sin.sin_len = sizeof(struct sockaddr_in);
111		sin.sin_family = AF_INET;
112		sin.sin_port = sin6->sin6_port;
113		memcpy(&sin.sin_addr, &sin6->sin6_addr.s6_addr[12],
114		       sizeof(struct in_addr));
115		addr = (struct sockaddr *)&sin;
116		addrlen = sin.sin_len;
117	}
118#endif
119
120	error = getnameinfo(addr, addrlen, buf, sizeof(buf), NULL, 0,
121			    NI_WITHSCOPEID);
122	if (error == 0) {
123		struct addrinfo hints, *res, *ores;
124		struct sockaddr *sa;
125
126		memset(&hints, 0, sizeof(struct addrinfo));
127		hints.ai_family = addr->sa_family;
128		hints.ai_flags = AI_CANONNAME | AI_PASSIVE;
129		hints.ai_socktype = SOCK_STREAM;
130
131		error = getaddrinfo(buf, NULL, &hints, &res);
132		if (error) {
133			result = HOSTNAME_INVALIDNAME;
134			goto numeric;
135		}
136		for (ores = res; ; res = res->ai_next) {
137			if (res == NULL) {
138				freeaddrinfo(ores);
139				result = HOSTNAME_INCORRECTNAME;
140				goto numeric;
141			}
142			sa = res->ai_addr;
143			if (sa == NULL) {
144				freeaddrinfo(ores);
145				result = HOSTNAME_INCORRECTNAME;
146				goto numeric;
147			}
148			if (sa->sa_len == addrlen &&
149			    sa->sa_family == addr->sa_family) {
150				((struct sockinet *)sa)->si_port = ((struct sockinet *)addr)->si_port;
151#ifdef INET6
152				/*
153				 * XXX: sin6_socpe_id may not been
154				 * filled by DNS
155				 */
156				if (sa->sa_family == AF_INET6 &&
157				    ((struct sockaddr_in6 *)sa)->sin6_scope_id == 0)
158					((struct sockaddr_in6 *)sa)->sin6_scope_id = ((struct sockaddr_in6 *)addr)->sin6_scope_id;
159#endif
160				if (!memcmp(sa, addr, sa->sa_len)) {
161					result = HOSTNAME_FOUND;
162					if (ores->ai_canonname == NULL) {
163						freeaddrinfo(ores);
164						goto numeric;
165					}
166					strlcpy(buf, ores->ai_canonname,
167						sizeof(buf));
168					trimdomain(buf, hsize);
169					if (strlen(buf) > hsize &&
170					    addr->sa_family == AF_INET) {
171						freeaddrinfo(ores);
172						goto numeric;
173					}
174					strncpy(host, buf, hsize);
175					break;
176				}
177			}
178		}
179		freeaddrinfo(ores);
180	} else {
181    numeric:
182		if (getnameinfo(addr, addrlen, buf, sizeof(buf), NULL, 0,
183				NI_NUMERICHOST|NI_WITHSCOPEID) == 0)
184			strncpy(host, buf, hsize);
185	}
186
187	return result;
188}
189
190
191