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#include <config.h> 35 36#include "roken.h" 37 38#undef roken_gethostbyname 39#undef roken_gethostbyaddr 40 41static struct sockaddr_in dns_addr; 42static char *dns_req; 43 44static int 45make_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 61static int 62setup_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 84static void 85split_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 107int ROKEN_LIB_FUNCTION 108roken_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); 123out: 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. */ 133static struct hostent* 134roken_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 210struct hostent* 211roken_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 220struct hostent* ROKEN_LIB_FUNCTION 221roken_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 246int 247main(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 272