1 /*        $NetBSD: roken_gethostby.c,v 1.2 2017/01/28 21:31:50 christos 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           if (asprintf(&dns_req, "%s", dns_path) < 0)
83               return -1;
84     }
85     dns_addr.sin_family = AF_INET;
86     return 0;
87 }
88 
89 static void
split_spec(const char * spec,char ** host,int * port,char ** path,int def_port)90 split_spec(const char *spec, char **host, int *port, char **path, int def_port)
91 {
92     char *p;
93     *host = strdup(spec);
94     p = strchr(*host, ':');
95     if(p) {
96           *p++ = '\0';
97           if(sscanf(p, "%d", port) != 1)
98               *port = def_port;
99     } else
100           *port = def_port;
101     p = strchr(p ? p : *host, '/');
102     if(p) {
103           if(path)
104               *path = strdup(p);
105           *p = '\0';
106     }else
107           if(path)
108               *path = NULL;
109 }
110 
111 
112 ROKEN_LIB_FUNCTION int ROKEN_LIB_CALL
roken_gethostby_setup(const char * proxy_spec,const char * dns_spec)113 roken_gethostby_setup(const char *proxy_spec, const char *dns_spec)
114 {
115     char *proxy_host = NULL;
116     int proxy_port = 0;
117     char *dns_host, *dns_path;
118     int dns_port;
119 
120     int ret = -1;
121 
122     split_spec(dns_spec, &dns_host, &dns_port, &dns_path, 80);
123     if(dns_path == NULL)
124           goto out;
125     if(proxy_spec)
126           split_spec(proxy_spec, &proxy_host, &proxy_port, NULL, 80);
127     ret = setup_int(proxy_host, proxy_port, dns_host, dns_port, dns_path);
128 out:
129     free(proxy_host);
130     free(dns_host);
131     free(dns_path);
132     return ret;
133 }
134 
135 
136 /* Try to lookup a name or an ip-address using http as transport
137    mechanism. See the end of this file for an example program. */
138 static struct hostent*
roken_gethostby(const char * hostname)139 roken_gethostby(const char *hostname)
140 {
141     int s;
142     struct sockaddr_in addr;
143     char *request = NULL;
144     char buf[1024];
145     int offset = 0;
146     int n;
147     char *p, *foo;
148     size_t len;
149 
150     if(dns_addr.sin_family == 0)
151           return NULL; /* no configured host */
152     addr = dns_addr;
153     if (asprintf(&request, "GET %s?%s HTTP/1.0\r\n\r\n", dns_req, hostname) < 0)
154           return NULL;
155     if(request == NULL)
156           return NULL;
157     s  = socket(AF_INET, SOCK_STREAM, 0);
158     if(s < 0) {
159           free(request);
160           return NULL;
161     }
162     if(connect(s, (struct sockaddr*)&addr, sizeof(addr)) < 0) {
163           close(s);
164           free(request);
165           return NULL;
166     }
167 
168     len = strlen(request);
169     if(write(s, request, len) != (ssize_t)len) {
170           close(s);
171           free(request);
172           return NULL;
173     }
174     free(request);
175     while(1) {
176           n = read(s, buf + offset, sizeof(buf) - offset);
177           if(n <= 0)
178               break;
179           offset += n;
180     }
181     buf[offset] = '\0';
182     close(s);
183     p = strstr(buf, "\r\n\r\n"); /* find end of header */
184     if(p) p += 4;
185     else return NULL;
186     foo = NULL;
187     p = strtok_r(p, " \t\r\n", &foo);
188     if(p == NULL)
189           return NULL;
190     {
191           /* make a hostent to return */
192 #define MAX_ADDRS 16
193           static struct hostent he;
194           static char addrs[4 * MAX_ADDRS];
195           static char *addr_list[MAX_ADDRS + 1];
196           int num_addrs = 0;
197 
198           he.h_name = p;
199           he.h_aliases = NULL;
200           he.h_addrtype = AF_INET;
201           he.h_length = 4;
202 
203           while((p = strtok_r(NULL, " \t\r\n", &foo)) && num_addrs < MAX_ADDRS) {
204               struct in_addr ip;
205               inet_aton(p, &ip);
206               ip.s_addr = ntohl(ip.s_addr);
207               addr_list[num_addrs] = &addrs[num_addrs * 4];
208               addrs[num_addrs * 4 + 0] = (ip.s_addr >> 24) & 0xff;
209               addrs[num_addrs * 4 + 1] = (ip.s_addr >> 16) & 0xff;
210               addrs[num_addrs * 4 + 2] = (ip.s_addr >> 8) & 0xff;
211               addrs[num_addrs * 4 + 3] = (ip.s_addr >> 0) & 0xff;
212               addr_list[++num_addrs] = NULL;
213           }
214           he.h_addr_list = addr_list;
215           return &he;
216     }
217 }
218 
219 ROKEN_LIB_FUNCTION struct hostent* ROKEN_LIB_CALL
roken_gethostbyname(const char * hostname)220 roken_gethostbyname(const char *hostname)
221 {
222     struct hostent *he;
223     he = gethostbyname(hostname);
224     if(he)
225           return he;
226     return roken_gethostby(hostname);
227 }
228 
229 ROKEN_LIB_FUNCTION struct hostent* ROKEN_LIB_CALL
roken_gethostbyaddr(const void * addr,size_t len,int type)230 roken_gethostbyaddr(const void *addr, size_t len, int type)
231 {
232     struct in_addr a;
233     const char *p;
234     struct hostent *he;
235     he = gethostbyaddr(addr, len, type);
236     if(he)
237           return he;
238     if(type != AF_INET || len != 4)
239           return NULL;
240     p = addr;
241     a.s_addr = htonl((p[0] << 24) | (p[1] << 16) | (p[2] << 8) | p[3]);
242     return roken_gethostby(inet_ntoa(a));
243 }
244 
245 #if 0
246 
247 /* this program can be used as a cgi `script' to lookup names and
248    ip-addresses */
249 
250 #include <stdio.h>
251 #include <stdlib.h>
252 #include <netdb.h>
253 #include <sys/param.h>
254 
255 int
256 main(int argc, char **argv)
257 {
258     char *query = getenv("QUERY_STRING");
259     char host[MAXHOSTNAMELEN];
260     int i;
261     struct hostent *he;
262 
263     printf("Content-type: text/plain\n\n");
264     if(query == NULL)
265           exit(0);
266     he = gethostbyname(query);
267     strncpy(host, he->h_name, sizeof(host));
268     host[sizeof(host) - 1] = '\0';
269     he = gethostbyaddr(he->h_addr, he->h_length, AF_INET);
270     printf("%s\n", he->h_name);
271     for(i = 0; he->h_addr_list[i]; i++) {
272           struct in_addr ip;
273           unsigned char *p = (unsigned char*)he->h_addr_list[i];
274           ip.s_addr = htonl((p[0] << 24) | (p[1] << 16) | (p[2] << 8) | p[3]);
275           printf("%s\n", inet_ntoa(ip));
276     }
277     exit(0);
278 }
279 
280 #endif
281