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 #ifdef HAVE_CONFIG_H
  35 #include <config.h>
  36 RCSID("$Id$");
  37 #endif
  38
  39 #include "roken.h"
  40
  41 #undef roken_gethostbyname
  42 #undef roken_gethostbyaddr
  43
  44 static struct sockaddr_in dns_addr;
  45 static char *dns_req;
  46
  47 static int
  48 make_address(const char *address, struct in_addr *ip)
  49 {
  50     if(inet_aton(address, ip) == 0){
  51         /* try to resolve as hostname, it might work if the address we
  52            are trying to lookup is local, for instance a web proxy */
  53         struct hostent *he = gethostbyname(address);
  54         if(he) {
  55             unsigned char *p = (unsigned char*)he->h_addr;
  56             ip->s_addr = (p[0] << 24) | (p[1] << 16) | (p[2] << 8) | p[3];
  57         } else {
  58             return -1;
  59         }
  60     }
  61     return 0;
  62 }
  63
  64 static int
  65 setup_int(const char *proxy_host, short proxy_port,
  66           const char *dns_host, short dns_port,
  67           const char *dns_path)
  68 {
  69     memset(&dns_addr, 0, sizeof(dns_addr));
  70     if(dns_req)
  71         free(dns_req);
  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         asprintf(&dns_req, "http://%s:%d%s", dns_host, dns_port, dns_path);
  77     } else {
  78         if(make_address(dns_host, &dns_addr.sin_addr) != 0)
  79             return -1;
  80         dns_addr.sin_port = htons(dns_port);
  81         asprintf(&dns_req, "%s", dns_path);
  82     }
  83     dns_addr.sin_family = AF_INET;
  84     return 0;
  85 }
  86
  87 static void
  88 split_spec(const char *spec, char **host, int *port, char **path, int def_port)
  89 {
  90     char *p;
  91     *host = strdup(spec);
  92     p = strchr(*host, ':');
  93     if(p) {
  94         *p++ = '\0';
  95         if(sscanf(p, "%d", port) != 1)
  96             *port = def_port;
  97     } else
  98         *port = def_port;
  99     p = strchr(p ? p : *host, '/');
 100     if(p) {
 101         if(path)
 102             *path = strdup(p);
 103         *p = '\0';
 104     }else
 105         if(path)
 106             *path = NULL;
 107 }
 108
 109
 110 int ROKEN_LIB_FUNCTION
 111 roken_gethostby_setup(const char *proxy_spec, const char *dns_spec)
 112 {
 113     char *proxy_host = NULL;
 114     int proxy_port = 0;
 115     char *dns_host, *dns_path;
 116     int dns_port;
 117
 118     int ret = -1;
 119
 120     split_spec(dns_spec, &dns_host, &dns_port, &dns_path, 80);
 121     if(dns_path == NULL)
 122         goto out;
 123     if(proxy_spec)
 124         split_spec(proxy_spec, &proxy_host, &proxy_port, NULL, 80);
 125     ret = setup_int(proxy_host, proxy_port, dns_host, dns_port, dns_path);
 126 out:
 127     free(proxy_host);
 128     free(dns_host);
 129     free(dns_path);
 130     return ret;
 131 }
 132
 133
 134 /* Try to lookup a name or an ip-address using http as transport
 135    mechanism. See the end of this file for an example program. */
 136 static struct hostent*
 137 roken_gethostby(const char *hostname)
 138 {
 139     int s;
 140     struct sockaddr_in addr;
 141     char *request;
 142     char buf[1024];
 143     int offset = 0;
 144     int n;
 145     char *p, *foo;
 146
 147     if(dns_addr.sin_family == 0)
 148         return NULL; /* no configured host */
 149     addr = dns_addr;
 150     asprintf(&request, "GET %s?%s HTTP/1.0\r\n\r\n", dns_req, hostname);
 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 struct hostent*
 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 struct hostent* ROKEN_LIB_FUNCTION
 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