lib/roken/roken_gethostby.c

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