1
2 /* Copyright 1998 by the Massachusetts Institute of Technology.
3 *
4 * Permission to use, copy, modify, and distribute this
5 * software and its documentation for any purpose and without
6 * fee is hereby granted, provided that the above copyright
7 * notice appear in all copies and that both that copyright
8 * notice and this permission notice appear in supporting
9 * documentation, and that the name of M.I.T. not be used in
10 * advertising or publicity pertaining to distribution of the
11 * software without specific, written prior permission.
12 * M.I.T. makes no representations about the suitability of
13 * this software for any purpose. It is provided "as is"
14 * without express or implied warranty.
15 */
16 #include "ares_setup.h"
17
18 #ifdef HAVE_NETINET_IN_H
19 # include <netinet/in.h>
20 #endif
21 #ifdef HAVE_NETDB_H
22 # include <netdb.h>
23 #endif
24 #ifdef HAVE_ARPA_INET_H
25 # include <arpa/inet.h>
26 #endif
27
28 #include "ares_nameser.h"
29
30 #include "ares.h"
31 #include "ares_inet_net_pton.h"
32 #include "ares_platform.h"
33 #include "ares_private.h"
34
35 #ifdef WATT32
36 #undef WIN32
37 #endif
38
39 struct addr_query {
40 /* Arguments passed to ares_gethostbyaddr() */
41 ares_channel channel;
42 struct ares_addr addr;
43 ares_host_callback callback;
44 void *arg;
45
46 const char *remaining_lookups;
47 int timeouts;
48 };
49
50 static void next_lookup(struct addr_query *aquery);
51 static void addr_callback(void *arg, int status, int timeouts,
52 unsigned char *abuf, int alen);
53 static void end_aquery(struct addr_query *aquery, int status,
54 struct hostent *host);
55 static int file_lookup(struct ares_addr *addr, struct hostent **host);
56 static void ptr_rr_name(char *name, const struct ares_addr *addr);
57
ares_gethostbyaddr(ares_channel channel,const void * addr,int addrlen,int family,ares_host_callback callback,void * arg)58 void ares_gethostbyaddr(ares_channel channel, const void *addr, int addrlen,
59 int family, ares_host_callback callback, void *arg)
60 {
61 struct addr_query *aquery;
62
63 if (family != AF_INET && family != AF_INET6)
64 {
65 callback(arg, ARES_ENOTIMP, 0, NULL);
66 return;
67 }
68
69 if ((family == AF_INET && addrlen != sizeof(aquery->addr.addrV4)) ||
70 (family == AF_INET6 && addrlen != sizeof(aquery->addr.addrV6)))
71 {
72 callback(arg, ARES_ENOTIMP, 0, NULL);
73 return;
74 }
75
76 aquery = ares_malloc(sizeof(struct addr_query));
77 if (!aquery)
78 {
79 callback(arg, ARES_ENOMEM, 0, NULL);
80 return;
81 }
82 aquery->channel = channel;
83 if (family == AF_INET)
84 memcpy(&aquery->addr.addrV4, addr, sizeof(aquery->addr.addrV4));
85 else
86 memcpy(&aquery->addr.addrV6, addr, sizeof(aquery->addr.addrV6));
87 aquery->addr.family = family;
88 aquery->callback = callback;
89 aquery->arg = arg;
90 aquery->remaining_lookups = channel->lookups;
91 aquery->timeouts = 0;
92
93 next_lookup(aquery);
94 }
95
next_lookup(struct addr_query * aquery)96 static void next_lookup(struct addr_query *aquery)
97 {
98 const char *p;
99 char name[128];
100 int status;
101 struct hostent *host;
102
103 for (p = aquery->remaining_lookups; *p; p++)
104 {
105 switch (*p)
106 {
107 case 'b':
108 ptr_rr_name(name, &aquery->addr);
109 aquery->remaining_lookups = p + 1;
110 ares_query(aquery->channel, name, C_IN, T_PTR, addr_callback,
111 aquery);
112 return;
113 case 'f':
114 status = file_lookup(&aquery->addr, &host);
115
116 /* this status check below previously checked for !ARES_ENOTFOUND,
117 but we should not assume that this single error code is the one
118 that can occur, as that is in fact no longer the case */
119 if (status == ARES_SUCCESS)
120 {
121 end_aquery(aquery, status, host);
122 return;
123 }
124 break;
125 }
126 }
127 end_aquery(aquery, ARES_ENOTFOUND, NULL);
128 }
129
addr_callback(void * arg,int status,int timeouts,unsigned char * abuf,int alen)130 static void addr_callback(void *arg, int status, int timeouts,
131 unsigned char *abuf, int alen)
132 {
133 struct addr_query *aquery = (struct addr_query *) arg;
134 struct hostent *host;
135 size_t addrlen;
136
137 aquery->timeouts += timeouts;
138 if (status == ARES_SUCCESS)
139 {
140 if (aquery->addr.family == AF_INET)
141 {
142 addrlen = sizeof(aquery->addr.addrV4);
143 status = ares_parse_ptr_reply(abuf, alen, &aquery->addr.addrV4,
144 (int)addrlen, AF_INET, &host);
145 }
146 else
147 {
148 addrlen = sizeof(aquery->addr.addrV6);
149 status = ares_parse_ptr_reply(abuf, alen, &aquery->addr.addrV6,
150 (int)addrlen, AF_INET6, &host);
151 }
152 end_aquery(aquery, status, host);
153 }
154 else if (status == ARES_EDESTRUCTION || status == ARES_ECANCELLED)
155 end_aquery(aquery, status, NULL);
156 else
157 next_lookup(aquery);
158 }
159
end_aquery(struct addr_query * aquery,int status,struct hostent * host)160 static void end_aquery(struct addr_query *aquery, int status,
161 struct hostent *host)
162 {
163 aquery->callback(aquery->arg, status, aquery->timeouts, host);
164 if (host)
165 ares_free_hostent(host);
166 ares_free(aquery);
167 }
168
file_lookup(struct ares_addr * addr,struct hostent ** host)169 static int file_lookup(struct ares_addr *addr, struct hostent **host)
170 {
171 FILE *fp;
172 int status;
173 int error;
174
175 #ifdef WIN32
176 char PATH_HOSTS[MAX_PATH];
177 win_platform platform;
178
179 PATH_HOSTS[0] = '\0';
180
181 platform = ares__getplatform();
182
183 if (platform == WIN_NT) {
184 char tmp[MAX_PATH];
185 HKEY hkeyHosts;
186
187 if (RegOpenKeyExA(HKEY_LOCAL_MACHINE, WIN_NS_NT_KEY, 0, KEY_READ,
188 &hkeyHosts) == ERROR_SUCCESS)
189 {
190 DWORD dwLength = MAX_PATH;
191 RegQueryValueExA(hkeyHosts, DATABASEPATH, NULL, NULL, (LPBYTE)tmp,
192 &dwLength);
193 ExpandEnvironmentStringsA(tmp, PATH_HOSTS, MAX_PATH);
194 RegCloseKey(hkeyHosts);
195 }
196 }
197 else if (platform == WIN_9X)
198 GetWindowsDirectoryA(PATH_HOSTS, MAX_PATH);
199 else
200 return ARES_ENOTFOUND;
201
202 strcat(PATH_HOSTS, WIN_PATH_HOSTS);
203
204 #elif defined(WATT32)
205 const char *PATH_HOSTS = _w32_GetHostsFile();
206
207 if (!PATH_HOSTS)
208 return ARES_ENOTFOUND;
209 #endif
210
211 fp = fopen(PATH_HOSTS, "r");
212 if (!fp)
213 {
214 error = ERRNO;
215 switch(error)
216 {
217 case ENOENT:
218 case ESRCH:
219 return ARES_ENOTFOUND;
220 default:
221 DEBUGF(fprintf(stderr, "fopen() failed with error: %d %s\n",
222 error, strerror(error)));
223 DEBUGF(fprintf(stderr, "Error opening file: %s\n",
224 PATH_HOSTS));
225 *host = NULL;
226 return ARES_EFILE;
227 }
228 }
229 while ((status = ares__get_hostent(fp, addr->family, host)) == ARES_SUCCESS)
230 {
231 if (addr->family != (*host)->h_addrtype)
232 {
233 ares_free_hostent(*host);
234 continue;
235 }
236 if (addr->family == AF_INET)
237 {
238 if (memcmp((*host)->h_addr, &addr->addrV4,
239 sizeof(addr->addrV4)) == 0)
240 break;
241 }
242 else if (addr->family == AF_INET6)
243 {
244 if (memcmp((*host)->h_addr, &addr->addrV6,
245 sizeof(addr->addrV6)) == 0)
246 break;
247 }
248 ares_free_hostent(*host);
249 }
250 fclose(fp);
251 if (status == ARES_EOF)
252 status = ARES_ENOTFOUND;
253 if (status != ARES_SUCCESS)
254 *host = NULL;
255 return status;
256 }
257
ptr_rr_name(char * name,const struct ares_addr * addr)258 static void ptr_rr_name(char *name, const struct ares_addr *addr)
259 {
260 if (addr->family == AF_INET)
261 {
262 unsigned long laddr = ntohl(addr->addrV4.s_addr);
263 unsigned long a1 = (laddr >> 24UL) & 0xFFUL;
264 unsigned long a2 = (laddr >> 16UL) & 0xFFUL;
265 unsigned long a3 = (laddr >> 8UL) & 0xFFUL;
266 unsigned long a4 = laddr & 0xFFUL;
267 sprintf(name, "%lu.%lu.%lu.%lu.in-addr.arpa", a4, a3, a2, a1);
268 }
269 else
270 {
271 unsigned char *bytes = (unsigned char *)&addr->addrV6;
272 /* There are too many arguments to do this in one line using
273 * minimally C89-compliant compilers */
274 sprintf(name,
275 "%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.",
276 bytes[15]&0xf, bytes[15] >> 4, bytes[14]&0xf, bytes[14] >> 4,
277 bytes[13]&0xf, bytes[13] >> 4, bytes[12]&0xf, bytes[12] >> 4,
278 bytes[11]&0xf, bytes[11] >> 4, bytes[10]&0xf, bytes[10] >> 4,
279 bytes[9]&0xf, bytes[9] >> 4, bytes[8]&0xf, bytes[8] >> 4);
280 sprintf(name+strlen(name),
281 "%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.ip6.arpa",
282 bytes[7]&0xf, bytes[7] >> 4, bytes[6]&0xf, bytes[6] >> 4,
283 bytes[5]&0xf, bytes[5] >> 4, bytes[4]&0xf, bytes[4] >> 4,
284 bytes[3]&0xf, bytes[3] >> 4, bytes[2]&0xf, bytes[2] >> 4,
285 bytes[1]&0xf, bytes[1] >> 4, bytes[0]&0xf, bytes[0] >> 4);
286 }
287 }
288