1 /* 2 * Copyright (c) 1998 Kungliga Tekniska H�gskolan 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: roken_gethostby.c,v 1.5 1999/12/05 13:16:44 assar Exp $"); 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 111 roken_gethostby_setup(const char *proxy_spec, const char *dns_spec) 112 { 113 char *proxy_host = NULL; 114 int proxy_port; 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 sin; 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 sin = 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*)&sin, sizeof(sin)) < 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]; 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* 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 275