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
41 struct sockinet {
42 u_char si_len;
43 u_char si_family;
44 u_short si_port;
45 };
46
47 int
realhostname(char * host,size_t hsize,const struct in_addr * ip)48 realhostname(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
97 int
realhostname_sa(char * host,size_t hsize,struct sockaddr * addr,int addrlen)98 realhostname_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