realhostname.c revision 57789 
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 57789 2000-03-07 07:52:01Z 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	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	char buf[NI_MAXHOST];
91
92	result = HOSTNAME_INVALIDADDR;
93
94	error = getnameinfo(addr, addrlen, buf, sizeof(buf), NULL, 0, 0);
95	if (error == 0) {
96		struct addrinfo hints, *res, *ores;
97		struct sockaddr *sa;
98
99		memset(&hints, 0, sizeof(struct addrinfo));
100		hints.ai_family =
101			(addr->sa_family == AF_INET) ? AF_INET : AF_UNSPEC;
102		hints.ai_flags = AI_CANONNAME;
103
104		error = getaddrinfo(buf, NULL, &hints, &res);
105		if (error) {
106			result = HOSTNAME_INVALIDNAME;
107			goto numeric;
108		} else for (ores = res; ; res = res->ai_next) {
109			if (res == NULL) {
110				freeaddrinfo(ores);
111				result = HOSTNAME_INCORRECTNAME;
112				goto numeric;
113			}
114			sa = res->ai_addr;
115			if (sa == NULL) {
116				freeaddrinfo(ores);
117				result = HOSTNAME_INCORRECTNAME;
118				goto numeric;
119			}
120			if (sa->sa_len == addrlen &&
121			    sa->sa_family == addr->sa_family) {
122				u_int16_t port;
123
124				port = ((struct sockinet *)addr)->si_port;
125				((struct sockinet *)addr)->si_port = 0;
126				if (!memcmp(sa, addr, sa->sa_len)) {
127					result = HOSTNAME_FOUND;
128					((struct sockinet *)addr)->si_port =
129						port;
130					if (res->ai_canonname == 0) {
131						freeaddrinfo(ores);
132						goto numeric;
133					}
134					if (strlen(res->ai_canonname) > hsize &&
135					    addr->sa_family == AF_INET) {
136						freeaddrinfo(ores);
137						goto numeric;
138					}
139					strncpy(host, res->ai_canonname,
140						hsize);
141					break;
142				}
143				((struct sockinet *)addr)->si_port = port;
144			}
145#ifdef INET6
146			/*
147			 * XXX IPv4 mapped IPv6 addr consideraton,
148			 * specified in rfc2373.
149			 */
150			if (sa->sa_family == AF_INET &&
151			    addr->sa_family == AF_INET6) {
152				struct in_addr *in;
153				struct in6_addr *in6;
154
155				in = &((struct sockaddr_in *)sa)->sin_addr;
156				in6 = &((struct sockaddr_in6 *)addr)->sin6_addr;
157				if (IN6_IS_ADDR_V4MAPPED(in6) &&
158				    !memcmp(&in6->s6_addr[12], in,
159					    sizeof(*in))) {
160					result = HOSTNAME_FOUND;
161					if (res->ai_canonname == 0) {
162						freeaddrinfo(ores);
163						goto numeric;
164					}
165					if (strlen(res->ai_canonname) > hsize)
166						strncpy(host, inet_ntoa(*in),
167							hsize);
168					else
169						strncpy(host,
170							res->ai_canonname,
171							hsize);
172					break;
173				}
174			}
175#endif
176		}
177		freeaddrinfo(ores);
178	} else {
179    numeric:
180		if (getnameinfo(addr, addrlen, buf, sizeof(buf), NULL, 0,
181				NI_NUMERICHOST|NI_WITHSCOPEID) == 0)
182			strncpy(host, buf, hsize);
183	}
184
185	return result;
186}
187
188
189