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 185277 2008-11-25 02:15:09Z avatar $
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 #include <libutil.h>
39
40 struct sockinet {
41 u_char si_len;
42 u_char si_family;
43 u_short si_port;
44 };
45
46 int
realhostname(char * host,size_t hsize,const struct in_addr * ip)47 realhostname(char *host, size_t hsize, const struct in_addr *ip)
48 {
49 char trimmed[MAXHOSTNAMELEN];
50 int result;
51 struct hostent *hp;
52
53 result = HOSTNAME_INVALIDADDR;
54 hp = gethostbyaddr((const char *)ip, sizeof(*ip), AF_INET);
55
56 if (hp != NULL) {
57 strlcpy(trimmed, hp->h_name, sizeof(trimmed));
58 trimdomain(trimmed, strlen(trimmed));
59 if (strlen(trimmed) <= hsize) {
60 char lookup[MAXHOSTNAMELEN];
61
62 strlcpy(lookup, hp->h_name, sizeof(lookup));
63 hp = gethostbyname(lookup);
64 if (hp == NULL)
65 result = HOSTNAME_INVALIDNAME;
66 else for (; ; hp->h_addr_list++) {
67 if (*hp->h_addr_list == NULL) {
68 result = HOSTNAME_INCORRECTNAME;
69 break;
70 }
71 if (!memcmp(*hp->h_addr_list, ip, sizeof(*ip))) {
72 strncpy(host, trimmed, hsize);
73 return HOSTNAME_FOUND;
74 }
75 }
76 }
77 }
78
79 strncpy(host, inet_ntoa(*ip), hsize);
80
81 return result;
82 }
83
84 /*
85 * struct sockaddr has very lax alignment requirements, since all its
86 * members are char or equivalent. This is a problem when trying to
87 * dereference a struct sockaddr_in6 * that was passed in as a struct
88 * sockaddr *. Although we know (or trust) that the passed-in struct was
89 * properly aligned, the compiler doesn't, and (rightly) complains. These
90 * macros perform the cast in a way that the compiler will accept.
91 */
92 #define SOCKADDR_IN6(p) ((struct sockaddr_in6 *)(void *)(p))
93 #define SOCKADDR_IN(p) ((struct sockaddr_in *)(void *)(p))
94 #define SOCKINET(p) ((struct sockinet *)(void *)(p))
95
96 int
realhostname_sa(char * host,size_t hsize,struct sockaddr * addr,int addrlen)97 realhostname_sa(char *host, size_t hsize, struct sockaddr *addr, int addrlen)
98 {
99 int result, error;
100 char buf[NI_MAXHOST];
101 #ifdef INET6
102 struct sockaddr_in lsin;
103 #endif
104
105 result = HOSTNAME_INVALIDADDR;
106
107 #ifdef INET6
108 /* IPv4 mapped IPv6 addr consideraton, specified in rfc2373. */
109 if (addr->sa_family == AF_INET6 &&
110 addrlen == sizeof(struct sockaddr_in6) &&
111 IN6_IS_ADDR_V4MAPPED(&SOCKADDR_IN6(addr)->sin6_addr)) {
112 struct sockaddr_in6 *sin6;
113
114 sin6 = SOCKADDR_IN6(addr);
115
116 memset(&lsin, 0, sizeof(lsin));
117 lsin.sin_len = sizeof(struct sockaddr_in);
118 lsin.sin_family = AF_INET;
119 lsin.sin_port = sin6->sin6_port;
120 memcpy(&lsin.sin_addr, &sin6->sin6_addr.s6_addr[12],
121 sizeof(struct in_addr));
122 addr = (struct sockaddr *)&lsin;
123 addrlen = lsin.sin_len;
124 }
125 #endif
126
127 error = getnameinfo(addr, addrlen, buf, sizeof(buf), NULL, 0,
128 NI_NAMEREQD);
129 if (error == 0) {
130 struct addrinfo hints, *res, *ores;
131 struct sockaddr *sa;
132
133 memset(&hints, 0, sizeof(struct addrinfo));
134 hints.ai_family = addr->sa_family;
135 hints.ai_flags = AI_CANONNAME | AI_PASSIVE;
136 hints.ai_socktype = SOCK_STREAM;
137
138 error = getaddrinfo(buf, NULL, &hints, &res);
139 if (error) {
140 result = HOSTNAME_INVALIDNAME;
141 goto numeric;
142 }
143 for (ores = res; ; res = res->ai_next) {
144 if (res == NULL) {
145 freeaddrinfo(ores);
146 result = HOSTNAME_INCORRECTNAME;
147 goto numeric;
148 }
149 sa = res->ai_addr;
150 if (sa == NULL) {
151 freeaddrinfo(ores);
152 result = HOSTNAME_INCORRECTNAME;
153 goto numeric;
154 }
155 if (sa->sa_len == addrlen &&
156 sa->sa_family == addr->sa_family) {
157 SOCKINET(sa)->si_port = SOCKINET(addr)->si_port;
158 #ifdef INET6
159 /*
160 * XXX: sin6_socpe_id may not been
161 * filled by DNS
162 */
163 if (sa->sa_family == AF_INET6 &&
164 SOCKADDR_IN6(sa)->sin6_scope_id == 0)
165 SOCKADDR_IN6(sa)->sin6_scope_id =
166 SOCKADDR_IN6(addr)->sin6_scope_id;
167 #endif
168 if (!memcmp(sa, addr, sa->sa_len)) {
169 result = HOSTNAME_FOUND;
170 if (ores->ai_canonname == NULL) {
171 freeaddrinfo(ores);
172 goto numeric;
173 }
174 strlcpy(buf, ores->ai_canonname,
175 sizeof(buf));
176 trimdomain(buf, hsize);
177 if (strlen(buf) > hsize &&
178 addr->sa_family == AF_INET) {
179 freeaddrinfo(ores);
180 goto numeric;
181 }
182 strncpy(host, buf, hsize);
183 break;
184 }
185 }
186 }
187 freeaddrinfo(ores);
188 } else {
189 numeric:
190 if (getnameinfo(addr, addrlen, buf, sizeof(buf), NULL, 0,
191 NI_NUMERICHOST) == 0)
192 strncpy(host, buf, hsize);
193 }
194
195 return result;
196 }
197
198
199