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 asprintf(&dns_req, "%s", dns_path); 81 } 82 dns_addr.sin_family = AF_INET; 83 return 0; 84 } 85 86 static void 87 split_spec(const char *spec, char **host, int *port, char **path, int def_port) 88 { 89 char *p; 90 *host = strdup(spec); 91 p = strchr(*host, ':'); 92 if(p) { 93 *p++ = '\0'; 94 if(sscanf(p, "%d", port) != 1) 95 *port = def_port; 96 } else 97 *port = def_port; 98 p = strchr(p ? p : *host, '/'); 99 if(p) { 100 if(path) 101 *path = strdup(p); 102 *p = '\0'; 103 }else 104 if(path) 105 *path = NULL; 106 } 107 108 109 ROKEN_LIB_FUNCTION int ROKEN_LIB_CALL 110 roken_gethostby_setup(const char *proxy_spec, const char *dns_spec) 111 { 112 char *proxy_host = NULL; 113 int proxy_port = 0; 114 char *dns_host, *dns_path; 115 int dns_port; 116 117 int ret = -1; 118 119 split_spec(dns_spec, &dns_host, &dns_port, &dns_path, 80); 120 if(dns_path == NULL) 121 goto out; 122 if(proxy_spec) 123 split_spec(proxy_spec, &proxy_host, &proxy_port, NULL, 80); 124 ret = setup_int(proxy_host, proxy_port, dns_host, dns_port, dns_path); 125 out: 126 free(proxy_host); 127 free(dns_host); 128 free(dns_path); 129 return ret; 130 } 131 132 133 /* Try to lookup a name or an ip-address using http as transport 134 mechanism. See the end of this file for an example program. */ 135 static struct hostent* 136 roken_gethostby(const char *hostname) 137 { 138 int s; 139 struct sockaddr_in addr; 140 char *request = NULL; 141 char buf[1024]; 142 int offset = 0; 143 int n; 144 char *p, *foo; 145 size_t len; 146 147 if(dns_addr.sin_family == 0) 148 return NULL; /* no configured host */ 149 addr = dns_addr; 150 if (asprintf(&request, "GET %s?%s HTTP/1.0\r\n\r\n", dns_req, hostname) < 0) 151 return NULL; 152 if(request == NULL) 153 return NULL; 154 s = socket(AF_INET, SOCK_STREAM, 0); 155 if(s < 0) { 156 free(request); 157 return NULL; 158 } 159 if(connect(s, (struct sockaddr*)&addr, sizeof(addr)) < 0) { 160 close(s); 161 free(request); 162 return NULL; 163 } 164 165 len = strlen(request); 166 if(write(s, request, len) != (ssize_t)len) { 167 close(s); 168 free(request); 169 return NULL; 170 } 171 free(request); 172 while(1) { 173 n = read(s, buf + offset, sizeof(buf) - offset); 174 if(n <= 0) 175 break; 176 offset += n; 177 } 178 buf[offset] = '\0'; 179 close(s); 180 p = strstr(buf, "\r\n\r\n"); /* find end of header */ 181 if(p) p += 4; 182 else return NULL; 183 foo = NULL; 184 p = strtok_r(p, " \t\r\n", &foo); 185 if(p == NULL) 186 return NULL; 187 { 188 /* make a hostent to return */ 189 #define MAX_ADDRS 16 190 static struct hostent he; 191 static char addrs[4 * MAX_ADDRS]; 192 static char *addr_list[MAX_ADDRS + 1]; 193 int num_addrs = 0; 194 195 he.h_name = p; 196 he.h_aliases = NULL; 197 he.h_addrtype = AF_INET; 198 he.h_length = 4; 199 200 while((p = strtok_r(NULL, " \t\r\n", &foo)) && num_addrs < MAX_ADDRS) { 201 struct in_addr ip; 202 inet_aton(p, &ip); 203 ip.s_addr = ntohl(ip.s_addr); 204 addr_list[num_addrs] = &addrs[num_addrs * 4]; 205 addrs[num_addrs * 4 + 0] = (ip.s_addr >> 24) & 0xff; 206 addrs[num_addrs * 4 + 1] = (ip.s_addr >> 16) & 0xff; 207 addrs[num_addrs * 4 + 2] = (ip.s_addr >> 8) & 0xff; 208 addrs[num_addrs * 4 + 3] = (ip.s_addr >> 0) & 0xff; 209 addr_list[++num_addrs] = NULL; 210 } 211 he.h_addr_list = addr_list; 212 return &he; 213 } 214 } 215 216 ROKEN_LIB_FUNCTION struct hostent* ROKEN_LIB_CALL 217 roken_gethostbyname(const char *hostname) 218 { 219 struct hostent *he; 220 he = gethostbyname(hostname); 221 if(he) 222 return he; 223 return roken_gethostby(hostname); 224 } 225 226 ROKEN_LIB_FUNCTION struct hostent* ROKEN_LIB_CALL 227 roken_gethostbyaddr(const void *addr, size_t len, int type) 228 { 229 struct in_addr a; 230 const char *p; 231 struct hostent *he; 232 he = gethostbyaddr(addr, len, type); 233 if(he) 234 return he; 235 if(type != AF_INET || len != 4) 236 return NULL; 237 p = addr; 238 a.s_addr = htonl((p[0] << 24) | (p[1] << 16) | (p[2] << 8) | p[3]); 239 return roken_gethostby(inet_ntoa(a)); 240 } 241 242 #if 0 243 244 /* this program can be used as a cgi `script' to lookup names and 245 ip-addresses */ 246 247 #include <stdio.h> 248 #include <stdlib.h> 249 #include <netdb.h> 250 #include <sys/param.h> 251 252 int 253 main(int argc, char **argv) 254 { 255 char *query = getenv("QUERY_STRING"); 256 char host[MAXHOSTNAMELEN]; 257 int i; 258 struct hostent *he; 259 260 printf("Content-type: text/plain\n\n"); 261 if(query == NULL) 262 exit(0); 263 he = gethostbyname(query); 264 strncpy(host, he->h_name, sizeof(host)); 265 host[sizeof(host) - 1] = '\0'; 266 he = gethostbyaddr(he->h_addr, he->h_length, AF_INET); 267 printf("%s\n", he->h_name); 268 for(i = 0; he->h_addr_list[i]; i++) { 269 struct in_addr ip; 270 unsigned char *p = (unsigned char*)he->h_addr_list[i]; 271 ip.s_addr = htonl((p[0] << 24) | (p[1] << 16) | (p[2] << 8) | p[3]); 272 printf("%s\n", inet_ntoa(ip)); 273 } 274 exit(0); 275 } 276 277 #endif 278