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     if(proxy_host) {
  70         if(make_address(proxy_host, &dns_addr.sin_addr) != 0)
  71             return -1;
  72         dns_addr.sin_port = htons(proxy_port);
  73         asprintf(&dns_req, "http://%s:%d%s", dns_host, dns_port, dns_path);
  74     } else {
  75         if(make_address(dns_host, &dns_addr.sin_addr) != 0)
  76             return -1;
  77         dns_addr.sin_port = htons(dns_port);
  78         asprintf(&dns_req, "%s", dns_path);
  79     }
  80     dns_addr.sin_family = AF_INET;
  81     return 0;
  82 }
  83
  84 static void
  85 split_spec(const char *spec, char **host, int *port, char **path, int def_port)
  86 {
  87     char *p;
  88     *host = strdup(spec);
  89     p = strchr(*host, ':');
  90     if(p) {
  91         *p++ = '\0';
  92         if(sscanf(p, "%d", port) != 1)
  93             *port = def_port;
  94     } else
  95         *port = def_port;
  96     p = strchr(p ? p : *host, '/');
  97     if(p) {
  98         if(path)
  99             *path = strdup(p);
 100         *p = '\0';
 101     }else
 102         if(path)
 103             *path = NULL;
 104 }
 105
 106
 107 int ROKEN_LIB_FUNCTION
 108 roken_gethostby_setup(const char *proxy_spec, const char *dns_spec)
 109 {
 110     char *proxy_host = NULL;
 111     int proxy_port = 0;
 112     char *dns_host, *dns_path;
 113     int dns_port;
 114
 115     int ret = -1;
 116
 117     split_spec(dns_spec, &dns_host, &dns_port, &dns_path, 80);
 118     if(dns_path == NULL)
 119         goto out;
 120     if(proxy_spec)
 121         split_spec(proxy_spec, &proxy_host, &proxy_port, NULL, 80);
 122     ret = setup_int(proxy_host, proxy_port, dns_host, dns_port, dns_path);
 123 out:
 124     free(proxy_host);
 125     free(dns_host);
 126     free(dns_path);
 127     return ret;
 128 }
 129
 130
 131 /* Try to lookup a name or an ip-address using http as transport
 132    mechanism. See the end of this file for an example program. */
 133 static struct hostent*
 134 roken_gethostby(const char *hostname)
 135 {
 136     int s;
 137     struct sockaddr_in addr;
 138     char *request;
 139     char buf[1024];
 140     int offset = 0;
 141     int n;
 142     char *p, *foo;
 143
 144     if(dns_addr.sin_family == 0)
 145         return NULL; /* no configured host */
 146     addr = dns_addr;
 147     asprintf(&request, "GET %s?%s HTTP/1.0\r\n\r\n", dns_req, hostname);
 148     if(request == NULL)
 149         return NULL;
 150     s  = socket(AF_INET, SOCK_STREAM, 0);
 151     if(s < 0) {
 152         free(request);
 153         return NULL;
 154     }
 155     if(connect(s, (struct sockaddr*)&addr, sizeof(addr)) < 0) {
 156         close(s);
 157         free(request);
 158         return NULL;
 159     }
 160     if(write(s, request, strlen(request)) != strlen(request)) {
 161         close(s);
 162         free(request);
 163         return NULL;
 164     }
 165     free(request);
 166     while(1) {
 167         n = read(s, buf + offset, sizeof(buf) - offset);
 168         if(n <= 0)
 169             break;
 170         offset += n;
 171     }
 172     buf[offset] = '\0';
 173     close(s);
 174     p = strstr(buf, "\r\n\r\n"); /* find end of header */
 175     if(p) p += 4;
 176     else return NULL;
 177     foo = NULL;
 178     p = strtok_r(p, " \t\r\n", &foo);
 179     if(p == NULL)
 180         return NULL;
 181     {
 182         /* make a hostent to return */
 183 #define MAX_ADDRS 16
 184         static struct hostent he;
 185         static char addrs[4 * MAX_ADDRS];
 186         static char *addr_list[MAX_ADDRS + 1];
 187         int num_addrs = 0;
 188
 189         he.h_name = p;
 190         he.h_aliases = NULL;
 191         he.h_addrtype = AF_INET;
 192         he.h_length = 4;
 193
 194         while((p = strtok_r(NULL, " \t\r\n", &foo)) && num_addrs < MAX_ADDRS) {
 195             struct in_addr ip;
 196             inet_aton(p, &ip);
 197             ip.s_addr = ntohl(ip.s_addr);
 198             addr_list[num_addrs] = &addrs[num_addrs * 4];
 199             addrs[num_addrs * 4 + 0] = (ip.s_addr >> 24) & 0xff;
 200             addrs[num_addrs * 4 + 1] = (ip.s_addr >> 16) & 0xff;
 201             addrs[num_addrs * 4 + 2] = (ip.s_addr >> 8) & 0xff;
 202             addrs[num_addrs * 4 + 3] = (ip.s_addr >> 0) & 0xff;
 203             addr_list[++num_addrs] = NULL;
 204         }
 205         he.h_addr_list = addr_list;
 206         return &he;
 207     }
 208 }
 209
 210 struct hostent*
 211 roken_gethostbyname(const char *hostname)
 212 {
 213     struct hostent *he;
 214     he = gethostbyname(hostname);
 215     if(he)
 216         return he;
 217     return roken_gethostby(hostname);
 218 }
 219
 220 struct hostent* ROKEN_LIB_FUNCTION
 221 roken_gethostbyaddr(const void *addr, size_t len, int type)
 222 {
 223     struct in_addr a;
 224     const char *p;
 225     struct hostent *he;
 226     he = gethostbyaddr(addr, len, type);
 227     if(he)
 228         return he;
 229     if(type != AF_INET || len != 4)
 230         return NULL;
 231     p = addr;
 232     a.s_addr = htonl((p[0] << 24) | (p[1] << 16) | (p[2] << 8) | p[3]);
 233     return roken_gethostby(inet_ntoa(a));
 234 }
 235
 236 #if 0
 237
 238 /* this program can be used as a cgi `script' to lookup names and
 239    ip-addresses */
 240
 241 #include <stdio.h>
 242 #include <stdlib.h>
 243 #include <netdb.h>
 244 #include <sys/param.h>
 245
 246 int
 247 main(int argc, char **argv)
 248 {
 249     char *query = getenv("QUERY_STRING");
 250     char host[MAXHOSTNAMELEN];
 251     int i;
 252     struct hostent *he;
 253
 254     printf("Content-type: text/plain\n\n");
 255     if(query == NULL)
 256         exit(0);
 257     he = gethostbyname(query);
 258     strncpy(host, he->h_name, sizeof(host));
 259     host[sizeof(host) - 1] = '\0';
 260     he = gethostbyaddr(he->h_addr, he->h_length, AF_INET);
 261     printf("%s\n", he->h_name);
 262     for(i = 0; he->h_addr_list[i]; i++) {
 263         struct in_addr ip;
 264         unsigned char *p = (unsigned char*)he->h_addr_list[i];
 265         ip.s_addr = htonl((p[0] << 24) | (p[1] << 16) | (p[2] << 8) | p[3]);
 266         printf("%s\n", inet_ntoa(ip));
 267     }
 268     exit(0);
 269 }
 270
 271 #endif