1/*-
2 * SPDX-License-Identifier: BSD-2-Clause
3 *
4 * Copyright (c) 1999 Brian Somers <brian@Awfulhak.org>
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
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
47int
48realhostname(char *host, size_t hsize, const struct in_addr *ip)
49{
50	char trimmed[MAXHOSTNAMELEN];
51	int result;
52	struct hostent *hp;
53
54	result = HOSTNAME_INVALIDADDR;
55	hp = gethostbyaddr((const char *)ip, sizeof(*ip), AF_INET);
56
57	if (hp != NULL) {
58		strlcpy(trimmed, hp->h_name, sizeof(trimmed));
59		trimdomain(trimmed, strlen(trimmed));
60		if (strlen(trimmed) <= hsize) {
61			char lookup[MAXHOSTNAMELEN];
62
63			strlcpy(lookup, hp->h_name, sizeof(lookup));
64			hp = gethostbyname(lookup);
65			if (hp == NULL)
66				result = HOSTNAME_INVALIDNAME;
67			else for (; ; hp->h_addr_list++) {
68				if (*hp->h_addr_list == NULL) {
69					result = HOSTNAME_INCORRECTNAME;
70					break;
71				}
72				if (!memcmp(*hp->h_addr_list, ip, sizeof(*ip))) {
73					strncpy(host, trimmed, hsize);
74					return HOSTNAME_FOUND;
75				}
76			}
77		}
78	}
79
80	strncpy(host, inet_ntoa(*ip), hsize);
81
82	return result;
83}
84
85/*
86 * struct sockaddr has very lax alignment requirements, since all its
87 * members are char or equivalent.  This is a problem when trying to
88 * dereference a struct sockaddr_in6 * that was passed in as a struct
89 * sockaddr *.  Although we know (or trust) that the passed-in struct was
90 * properly aligned, the compiler doesn't, and (rightly) complains.  These
91 * macros perform the cast in a way that the compiler will accept.
92 */
93#define SOCKADDR_IN6(p) ((struct sockaddr_in6 *)(void *)(p))
94#define SOCKADDR_IN(p) ((struct sockaddr_in *)(void *)(p))
95#define SOCKINET(p) ((struct sockinet *)(void *)(p))
96
97int
98realhostname_sa(char *host, size_t hsize, struct sockaddr *addr, int addrlen)
99{
100	int result, error;
101	char buf[NI_MAXHOST];
102#ifdef INET6
103	struct sockaddr_in lsin;
104#endif
105
106	result = HOSTNAME_INVALIDADDR;
107
108#ifdef INET6
109	/* IPv4 mapped IPv6 addr consideraton, specified in rfc2373. */
110	if (addr->sa_family == AF_INET6 &&
111	    addrlen == sizeof(struct sockaddr_in6) &&
112	    IN6_IS_ADDR_V4MAPPED(&SOCKADDR_IN6(addr)->sin6_addr)) {
113		struct sockaddr_in6 *sin6;
114
115		sin6 = SOCKADDR_IN6(addr);
116
117		memset(&lsin, 0, sizeof(lsin));
118		lsin.sin_len = sizeof(struct sockaddr_in);
119		lsin.sin_family = AF_INET;
120		lsin.sin_port = sin6->sin6_port;
121		memcpy(&lsin.sin_addr, &sin6->sin6_addr.s6_addr[12],
122		       sizeof(struct in_addr));
123		addr = (struct sockaddr *)&lsin;
124		addrlen = lsin.sin_len;
125	}
126#endif
127
128	error = getnameinfo(addr, addrlen, buf, sizeof(buf), NULL, 0,
129			    NI_NAMEREQD);
130	if (error == 0) {
131		struct addrinfo hints, *res, *ores;
132		struct sockaddr *sa;
133
134		memset(&hints, 0, sizeof(struct addrinfo));
135		hints.ai_family = addr->sa_family;
136		hints.ai_flags = AI_CANONNAME | AI_PASSIVE;
137		hints.ai_socktype = SOCK_STREAM;
138
139		error = getaddrinfo(buf, NULL, &hints, &res);
140		if (error) {
141			result = HOSTNAME_INVALIDNAME;
142			goto numeric;
143		}
144		for (ores = res; ; res = res->ai_next) {
145			if (res == NULL) {
146				freeaddrinfo(ores);
147				result = HOSTNAME_INCORRECTNAME;
148				goto numeric;
149			}
150			sa = res->ai_addr;
151			if (sa == NULL) {
152				freeaddrinfo(ores);
153				result = HOSTNAME_INCORRECTNAME;
154				goto numeric;
155			}
156			if (sa->sa_len == addrlen &&
157			    sa->sa_family == addr->sa_family) {
158				SOCKINET(sa)->si_port = SOCKINET(addr)->si_port;
159#ifdef INET6
160				/*
161				 * XXX: sin6_socpe_id may not been
162				 * filled by DNS
163				 */
164				if (sa->sa_family == AF_INET6 &&
165				    SOCKADDR_IN6(sa)->sin6_scope_id == 0)
166					SOCKADDR_IN6(sa)->sin6_scope_id =
167					    SOCKADDR_IN6(addr)->sin6_scope_id;
168#endif
169				if (!memcmp(sa, addr, sa->sa_len)) {
170					result = HOSTNAME_FOUND;
171					if (ores->ai_canonname == NULL) {
172						freeaddrinfo(ores);
173						goto numeric;
174					}
175					strlcpy(buf, ores->ai_canonname,
176						sizeof(buf));
177					trimdomain(buf, hsize);
178					if (strlen(buf) > hsize &&
179					    addr->sa_family == AF_INET) {
180						freeaddrinfo(ores);
181						goto numeric;
182					}
183					strncpy(host, buf, hsize);
184					break;
185				}
186			}
187		}
188		freeaddrinfo(ores);
189	} else {
190    numeric:
191		if (getnameinfo(addr, addrlen, buf, sizeof(buf), NULL, 0,
192				NI_NUMERICHOST) == 0)
193			strncpy(host, buf, hsize);
194	}
195
196	return result;
197}
198
199
200