1 /* $NetBSD: roken_gethostby.c,v 1.1.1.2 2014/04/24 12:45:52 pettai Exp $ */
2
3 /*
4 * Copyright (c) 1998 Kungliga Tekniska Högskolan
5 * (Royal Institute of Technology, Stockholm, Sweden).
6 * All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 *
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 *
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 *
19 * 3. Neither the name of the Institute nor the names of its contributors
20 * may be used to endorse or promote products derived from this software
21 * without specific prior written permission.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26 * ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33 * SUCH DAMAGE.
34 */
35
36 #include <config.h>
37
38 #include <krb5/roken.h>
39
40 #undef roken_gethostbyname
41 #undef roken_gethostbyaddr
42
43 static struct sockaddr_in dns_addr;
44 static char *dns_req;
45
46 static int
make_address(const char * address,struct in_addr * ip)47 make_address(const char *address, struct in_addr *ip)
48 {
49 if(inet_aton(address, ip) == 0){
50 /* try to resolve as hostname, it might work if the address we
51 are trying to lookup is local, for instance a web proxy */
52 struct hostent *he = gethostbyname(address);
53 if(he) {
54 unsigned char *p = (unsigned char*)he->h_addr;
55 ip->s_addr = (p[0] << 24) | (p[1] << 16) | (p[2] << 8) | p[3];
56 } else {
57 return -1;
58 }
59 }
60 return 0;
61 }
62
63 static int
setup_int(const char * proxy_host,short proxy_port,const char * dns_host,short dns_port,const char * dns_path)64 setup_int(const char *proxy_host, short proxy_port,
65 const char *dns_host, short dns_port,
66 const char *dns_path)
67 {
68 memset(&dns_addr, 0, sizeof(dns_addr));
69 if(dns_req)
70 free(dns_req);
71 dns_req = NULL;
72 if(proxy_host) {
73 if(make_address(proxy_host, &dns_addr.sin_addr) != 0)
74 return -1;
75 dns_addr.sin_port = htons(proxy_port);
76 if (asprintf(&dns_req, "http://%s:%d%s", dns_host, dns_port, dns_path) < 0)
77 return -1;
78 } else {
79 if(make_address(dns_host, &dns_addr.sin_addr) != 0)
80 return -1;
81 dns_addr.sin_port = htons(dns_port);
82 asprintf(&dns_req, "%s", dns_path);
83 }
84 dns_addr.sin_family = AF_INET;
85 return 0;
86 }
87
88 static void
split_spec(const char * spec,char ** host,int * port,char ** path,int def_port)89 split_spec(const char *spec, char **host, int *port, char **path, int def_port)
90 {
91 char *p;
92 *host = strdup(spec);
93 p = strchr(*host, ':');
94 if(p) {
95 *p++ = '\0';
96 if(sscanf(p, "%d", port) != 1)
97 *port = def_port;
98 } else
99 *port = def_port;
100 p = strchr(p ? p : *host, '/');
101 if(p) {
102 if(path)
103 *path = strdup(p);
104 *p = '\0';
105 }else
106 if(path)
107 *path = NULL;
108 }
109
110
111 ROKEN_LIB_FUNCTION int ROKEN_LIB_CALL
roken_gethostby_setup(const char * proxy_spec,const char * dns_spec)112 roken_gethostby_setup(const char *proxy_spec, const char *dns_spec)
113 {
114 char *proxy_host = NULL;
115 int proxy_port = 0;
116 char *dns_host, *dns_path;
117 int dns_port;
118
119 int ret = -1;
120
121 split_spec(dns_spec, &dns_host, &dns_port, &dns_path, 80);
122 if(dns_path == NULL)
123 goto out;
124 if(proxy_spec)
125 split_spec(proxy_spec, &proxy_host, &proxy_port, NULL, 80);
126 ret = setup_int(proxy_host, proxy_port, dns_host, dns_port, dns_path);
127 out:
128 free(proxy_host);
129 free(dns_host);
130 free(dns_path);
131 return ret;
132 }
133
134
135 /* Try to lookup a name or an ip-address using http as transport
136 mechanism. See the end of this file for an example program. */
137 static struct hostent*
roken_gethostby(const char * hostname)138 roken_gethostby(const char *hostname)
139 {
140 int s;
141 struct sockaddr_in addr;
142 char *request = NULL;
143 char buf[1024];
144 int offset = 0;
145 int n;
146 char *p, *foo;
147 size_t len;
148
149 if(dns_addr.sin_family == 0)
150 return NULL; /* no configured host */
151 addr = dns_addr;
152 if (asprintf(&request, "GET %s?%s HTTP/1.0\r\n\r\n", dns_req, hostname) < 0)
153 return NULL;
154 if(request == NULL)
155 return NULL;
156 s = socket(AF_INET, SOCK_STREAM, 0);
157 if(s < 0) {
158 free(request);
159 return NULL;
160 }
161 if(connect(s, (struct sockaddr*)&addr, sizeof(addr)) < 0) {
162 close(s);
163 free(request);
164 return NULL;
165 }
166
167 len = strlen(request);
168 if(write(s, request, len) != (ssize_t)len) {
169 close(s);
170 free(request);
171 return NULL;
172 }
173 free(request);
174 while(1) {
175 n = read(s, buf + offset, sizeof(buf) - offset);
176 if(n <= 0)
177 break;
178 offset += n;
179 }
180 buf[offset] = '\0';
181 close(s);
182 p = strstr(buf, "\r\n\r\n"); /* find end of header */
183 if(p) p += 4;
184 else return NULL;
185 foo = NULL;
186 p = strtok_r(p, " \t\r\n", &foo);
187 if(p == NULL)
188 return NULL;
189 {
190 /* make a hostent to return */
191 #define MAX_ADDRS 16
192 static struct hostent he;
193 static char addrs[4 * MAX_ADDRS];
194 static char *addr_list[MAX_ADDRS + 1];
195 int num_addrs = 0;
196
197 he.h_name = p;
198 he.h_aliases = NULL;
199 he.h_addrtype = AF_INET;
200 he.h_length = 4;
201
202 while((p = strtok_r(NULL, " \t\r\n", &foo)) && num_addrs < MAX_ADDRS) {
203 struct in_addr ip;
204 inet_aton(p, &ip);
205 ip.s_addr = ntohl(ip.s_addr);
206 addr_list[num_addrs] = &addrs[num_addrs * 4];
207 addrs[num_addrs * 4 + 0] = (ip.s_addr >> 24) & 0xff;
208 addrs[num_addrs * 4 + 1] = (ip.s_addr >> 16) & 0xff;
209 addrs[num_addrs * 4 + 2] = (ip.s_addr >> 8) & 0xff;
210 addrs[num_addrs * 4 + 3] = (ip.s_addr >> 0) & 0xff;
211 addr_list[++num_addrs] = NULL;
212 }
213 he.h_addr_list = addr_list;
214 return &he;
215 }
216 }
217
218 ROKEN_LIB_FUNCTION struct hostent* ROKEN_LIB_CALL
roken_gethostbyname(const char * hostname)219 roken_gethostbyname(const char *hostname)
220 {
221 struct hostent *he;
222 he = gethostbyname(hostname);
223 if(he)
224 return he;
225 return roken_gethostby(hostname);
226 }
227
228 ROKEN_LIB_FUNCTION struct hostent* ROKEN_LIB_CALL
roken_gethostbyaddr(const void * addr,size_t len,int type)229 roken_gethostbyaddr(const void *addr, size_t len, int type)
230 {
231 struct in_addr a;
232 const char *p;
233 struct hostent *he;
234 he = gethostbyaddr(addr, len, type);
235 if(he)
236 return he;
237 if(type != AF_INET || len != 4)
238 return NULL;
239 p = addr;
240 a.s_addr = htonl((p[0] << 24) | (p[1] << 16) | (p[2] << 8) | p[3]);
241 return roken_gethostby(inet_ntoa(a));
242 }
243
244 #if 0
245
246 /* this program can be used as a cgi `script' to lookup names and
247 ip-addresses */
248
249 #include <stdio.h>
250 #include <stdlib.h>
251 #include <netdb.h>
252 #include <sys/param.h>
253
254 int
255 main(int argc, char **argv)
256 {
257 char *query = getenv("QUERY_STRING");
258 char host[MAXHOSTNAMELEN];
259 int i;
260 struct hostent *he;
261
262 printf("Content-type: text/plain\n\n");
263 if(query == NULL)
264 exit(0);
265 he = gethostbyname(query);
266 strncpy(host, he->h_name, sizeof(host));
267 host[sizeof(host) - 1] = '\0';
268 he = gethostbyaddr(he->h_addr, he->h_length, AF_INET);
269 printf("%s\n", he->h_name);
270 for(i = 0; he->h_addr_list[i]; i++) {
271 struct in_addr ip;
272 unsigned char *p = (unsigned char*)he->h_addr_list[i];
273 ip.s_addr = htonl((p[0] << 24) | (p[1] << 16) | (p[2] << 8) | p[3]);
274 printf("%s\n", inet_ntoa(ip));
275 }
276 exit(0);
277 }
278
279 #endif
280