1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause
3 *
4 * Copyright (c) 1999 Brian Somers <[email protected]>
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/cdefs.h>
30 #include <sys/param.h>
31 #include <sys/socket.h>
32
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 struct sockinet {
43 u_char si_len;
44 u_char si_family;
45 u_short si_port;
46 };
47
48 int
realhostname(char * host,size_t hsize,const struct in_addr * ip)49 realhostname(char *host, size_t hsize, const struct in_addr *ip)
50 {
51 char trimmed[MAXHOSTNAMELEN];
52 int result;
53 struct hostent *hp;
54
55 result = HOSTNAME_INVALIDADDR;
56 hp = gethostbyaddr((const char *)ip, sizeof(*ip), AF_INET);
57
58 if (hp != NULL) {
59 strlcpy(trimmed, hp->h_name, sizeof(trimmed));
60 trimdomain(trimmed, strlen(trimmed));
61 if (strlen(trimmed) <= hsize) {
62 char lookup[MAXHOSTNAMELEN];
63
64 strlcpy(lookup, hp->h_name, sizeof(lookup));
65 hp = gethostbyname(lookup);
66 if (hp == NULL)
67 result = HOSTNAME_INVALIDNAME;
68 else for (; ; hp->h_addr_list++) {
69 if (*hp->h_addr_list == NULL) {
70 result = HOSTNAME_INCORRECTNAME;
71 break;
72 }
73 if (!memcmp(*hp->h_addr_list, ip, sizeof(*ip))) {
74 strncpy(host, trimmed, hsize);
75 return HOSTNAME_FOUND;
76 }
77 }
78 }
79 }
80
81 strncpy(host, inet_ntoa(*ip), hsize);
82
83 return result;
84 }
85
86 /*
87 * struct sockaddr has very lax alignment requirements, since all its
88 * members are char or equivalent. This is a problem when trying to
89 * dereference a struct sockaddr_in6 * that was passed in as a struct
90 * sockaddr *. Although we know (or trust) that the passed-in struct was
91 * properly aligned, the compiler doesn't, and (rightly) complains. These
92 * macros perform the cast in a way that the compiler will accept.
93 */
94 #define SOCKADDR_IN6(p) ((struct sockaddr_in6 *)(void *)(p))
95 #define SOCKADDR_IN(p) ((struct sockaddr_in *)(void *)(p))
96 #define SOCKINET(p) ((struct sockinet *)(void *)(p))
97
98 int
realhostname_sa(char * host,size_t hsize,struct sockaddr * addr,int addrlen)99 realhostname_sa(char *host, size_t hsize, struct sockaddr *addr, int addrlen)
100 {
101 int result, error;
102 char buf[NI_MAXHOST];
103 #ifdef INET6
104 struct sockaddr_in lsin;
105 #endif
106
107 result = HOSTNAME_INVALIDADDR;
108
109 #ifdef INET6
110 /* IPv4 mapped IPv6 addr consideraton, specified in rfc2373. */
111 if (addr->sa_family == AF_INET6 &&
112 addrlen == sizeof(struct sockaddr_in6) &&
113 IN6_IS_ADDR_V4MAPPED(&SOCKADDR_IN6(addr)->sin6_addr)) {
114 struct sockaddr_in6 *sin6;
115
116 sin6 = SOCKADDR_IN6(addr);
117
118 memset(&lsin, 0, sizeof(lsin));
119 lsin.sin_len = sizeof(struct sockaddr_in);
120 lsin.sin_family = AF_INET;
121 lsin.sin_port = sin6->sin6_port;
122 memcpy(&lsin.sin_addr, &sin6->sin6_addr.s6_addr[12],
123 sizeof(struct in_addr));
124 addr = (struct sockaddr *)&lsin;
125 addrlen = lsin.sin_len;
126 }
127 #endif
128
129 error = getnameinfo(addr, addrlen, buf, sizeof(buf), NULL, 0,
130 NI_NAMEREQD);
131 if (error == 0) {
132 struct addrinfo hints, *res, *ores;
133 struct sockaddr *sa;
134
135 memset(&hints, 0, sizeof(struct addrinfo));
136 hints.ai_family = addr->sa_family;
137 hints.ai_flags = AI_CANONNAME | AI_PASSIVE;
138 hints.ai_socktype = SOCK_STREAM;
139
140 error = getaddrinfo(buf, NULL, &hints, &res);
141 if (error) {
142 result = HOSTNAME_INVALIDNAME;
143 goto numeric;
144 }
145 for (ores = res; ; res = res->ai_next) {
146 if (res == NULL) {
147 freeaddrinfo(ores);
148 result = HOSTNAME_INCORRECTNAME;
149 goto numeric;
150 }
151 sa = res->ai_addr;
152 if (sa == NULL) {
153 freeaddrinfo(ores);
154 result = HOSTNAME_INCORRECTNAME;
155 goto numeric;
156 }
157 if (sa->sa_len == addrlen &&
158 sa->sa_family == addr->sa_family) {
159 SOCKINET(sa)->si_port = SOCKINET(addr)->si_port;
160 #ifdef INET6
161 /*
162 * XXX: sin6_socpe_id may not been
163 * filled by DNS
164 */
165 if (sa->sa_family == AF_INET6 &&
166 SOCKADDR_IN6(sa)->sin6_scope_id == 0)
167 SOCKADDR_IN6(sa)->sin6_scope_id =
168 SOCKADDR_IN6(addr)->sin6_scope_id;
169 #endif
170 if (!memcmp(sa, addr, sa->sa_len)) {
171 result = HOSTNAME_FOUND;
172 if (ores->ai_canonname == NULL) {
173 freeaddrinfo(ores);
174 goto numeric;
175 }
176 strlcpy(buf, ores->ai_canonname,
177 sizeof(buf));
178 trimdomain(buf, hsize);
179 if (strlen(buf) > hsize &&
180 addr->sa_family == AF_INET) {
181 freeaddrinfo(ores);
182 goto numeric;
183 }
184 strncpy(host, buf, hsize);
185 break;
186 }
187 }
188 }
189 freeaddrinfo(ores);
190 } else {
191 numeric:
192 if (getnameinfo(addr, addrlen, buf, sizeof(buf), NULL, 0,
193 NI_NUMERICHOST) == 0)
194 strncpy(host, buf, hsize);
195 }
196
197 return result;
198 }
199
200
201