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         if (asprintf(&dns_req, "%s", dns_path) < 0)
  81             return -1;
  82     }
  83     dns_addr.sin_family = AF_INET;
  84     return 0;
  85 }
  86
  87 static int
  88 split_spec(const char *spec, char **host, int *port, char **path, int def_port)
  89 {
  90     char *p;
  91     *host = strdup(spec);
  92     if (*host == NULL)
  93         return -1;
  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             if (*path == NULL) {
 106                 free(*host);
 107                 *host = NULL;
 108                 return -1;
 109             }
 110         }
 111         *p = '\0';
 112     }else
 113         if(path)
 114             *path = NULL;
 115     return 0;
 116 }
 117
 118
 119 ROKEN_LIB_FUNCTION int ROKEN_LIB_CALL
 120 roken_gethostby_setup(const char *proxy_spec, const char *dns_spec)
 121 {
 122     char *proxy_host = NULL;
 123     int proxy_port = 0;
 124     char *dns_host = NULL, *dns_path = NULL;
 125     int dns_port;
 126     int ret;
 127
 128     ret = split_spec(dns_spec, &dns_host, &dns_port, &dns_path, 80);
 129     if(ret)
 130         goto out;
 131     if(proxy_spec) {
 132         ret = split_spec(proxy_spec, &proxy_host, &proxy_port, NULL, 80);
 133         if (ret)
 134             goto out;
 135     }
 136     ret = setup_int(proxy_host, proxy_port, dns_host, dns_port, dns_path);
 137     if (ret)
 138         goto out;
 139
 140 out:
 141     free(proxy_host);
 142     free(dns_host);
 143     free(dns_path);
 144     return ret;
 145 }
 146
 147
 148 /* Try to lookup a name or an ip-address using http as transport
 149    mechanism. See the end of this file for an example program. */
 150 static struct hostent*
 151 roken_gethostby(const char *hostname)
 152 {
 153     int s;
 154     struct sockaddr_in addr;
 155     char *request = NULL;
 156     char buf[1024];
 157     int offset = 0;
 158     int n;
 159     char *p, *foo;
 160     size_t len;
 161
 162     if(dns_addr.sin_family == 0)
 163         return NULL; /* no configured host */
 164     addr = dns_addr;
 165     if (asprintf(&request, "GET %s?%s HTTP/1.0\r\n\r\n", dns_req, hostname) < 0)
 166         return NULL;
 167     if(request == NULL)
 168         return NULL;
 169     s  = socket(AF_INET, SOCK_STREAM, 0);
 170     if(s < 0) {
 171         free(request);
 172         return NULL;
 173     }
 174     if(connect(s, (struct sockaddr*)&addr, sizeof(addr)) < 0) {
 175         close(s);
 176         free(request);
 177         return NULL;
 178     }
 179
 180     len = strlen(request);
 181     if(write(s, request, len) != (ssize_t)len) {
 182         close(s);
 183         free(request);
 184         return NULL;
 185     }
 186     free(request);
 187     while(1) {
 188         n = read(s, buf + offset, sizeof(buf) - offset);
 189         if(n <= 0)
 190             break;
 191         offset += n;
 192     }
 193     buf[offset] = '\0';
 194     close(s);
 195     p = strstr(buf, "\r\n\r\n"); /* find end of header */
 196     if(p) p += 4;
 197     else return NULL;
 198     foo = NULL;
 199     p = strtok_r(p, " \t\r\n", &foo);
 200     if(p == NULL)
 201         return NULL;
 202     {
 203         /* make a hostent to return */
 204 #define MAX_ADDRS 16
 205         static struct hostent he;
 206         static char addrs[4 * MAX_ADDRS];
 207         static char *addr_list[MAX_ADDRS + 1];
 208         int num_addrs = 0;
 209
 210         he.h_name = p;
 211         he.h_aliases = NULL;
 212         he.h_addrtype = AF_INET;
 213         he.h_length = 4;
 214
 215         while((p = strtok_r(NULL, " \t\r\n", &foo)) && num_addrs < MAX_ADDRS) {
 216             struct in_addr ip;
 217             inet_aton(p, &ip);
 218             ip.s_addr = ntohl(ip.s_addr);
 219             addr_list[num_addrs] = &addrs[num_addrs * 4];
 220             addrs[num_addrs * 4 + 0] = (ip.s_addr >> 24) & 0xff;
 221             addrs[num_addrs * 4 + 1] = (ip.s_addr >> 16) & 0xff;
 222             addrs[num_addrs * 4 + 2] = (ip.s_addr >> 8) & 0xff;
 223             addrs[num_addrs * 4 + 3] = (ip.s_addr >> 0) & 0xff;
 224             addr_list[++num_addrs] = NULL;
 225         }
 226         he.h_addr_list = addr_list;
 227         return &he;
 228     }
 229 }
 230
 231 ROKEN_LIB_FUNCTION struct hostent* ROKEN_LIB_CALL
 232 roken_gethostbyname(const char *hostname)
 233 {
 234     struct hostent *he;
 235     he = gethostbyname(hostname);
 236     if(he)
 237         return he;
 238     return roken_gethostby(hostname);
 239 }
 240
 241 ROKEN_LIB_FUNCTION struct hostent* ROKEN_LIB_CALL
 242 roken_gethostbyaddr(const void *addr, size_t len, int type)
 243 {
 244     struct in_addr a;
 245     const char *p;
 246     struct hostent *he;
 247     he = gethostbyaddr(addr, len, type);
 248     if(he)
 249         return he;
 250     if(type != AF_INET || len != 4)
 251         return NULL;
 252     p = addr;
 253     a.s_addr = htonl((p[0] << 24) | (p[1] << 16) | (p[2] << 8) | p[3]);
 254     return roken_gethostby(inet_ntoa(a));
 255 }
 256
 257 #if 0
 258
 259 /* this program can be used as a cgi `script' to lookup names and
 260    ip-addresses */
 261
 262 #include <stdio.h>
 263 #include <stdlib.h>
 264 #include <netdb.h>
 265 #include <sys/param.h>
 266
 267 int
 268 main(int argc, char **argv)
 269 {
 270     char *query = getenv("QUERY_STRING");
 271     char host[MAXHOSTNAMELEN];
 272     int i;
 273     struct hostent *he;
 274
 275     printf("Content-type: text/plain\n\n");
 276     if(query == NULL)
 277         exit(0);
 278     he = gethostbyname(query);
 279     strncpy(host, he->h_name, sizeof(host));
 280     host[sizeof(host) - 1] = '\0';
 281     he = gethostbyaddr(he->h_addr, he->h_length, AF_INET);
 282     printf("%s\n", he->h_name);
 283     for(i = 0; he->h_addr_list[i]; i++) {
 284         struct in_addr ip;
 285         unsigned char *p = (unsigned char*)he->h_addr_list[i];
 286         ip.s_addr = htonl((p[0] << 24) | (p[1] << 16) | (p[2] << 8) | p[3]);
 287         printf("%s\n", inet_ntoa(ip));
 288     }
 289     exit(0);
 290 }
 291
 292 #endif