1 /* $NetBSD: roken_gethostby.c,v 1.1.1.2 2014/04/24 12:45:52 pettai Exp $ */ 2 3 /* 4 * Copyright (c) 1998 Kungliga Tekniska Högskolan 5 * (Royal Institute of Technology, Stockholm, Sweden). 6 * All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 19 * 3. Neither the name of the Institute nor the names of its contributors 20 * may be used to endorse or promote products derived from this software 21 * without specific prior written permission. 22 * 23 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND 24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26 * ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE 27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33 * SUCH DAMAGE. 34 */ 35 36 #include <config.h> 37 38 #include <krb5/roken.h> 39 40 #undef roken_gethostbyname 41 #undef roken_gethostbyaddr 42 43 static struct sockaddr_in dns_addr; 44 static char *dns_req; 45 46 static int 47 make_address(const char *address, struct in_addr *ip) 48 { 49 if(inet_aton(address, ip) == 0){ 50 /* try to resolve as hostname, it might work if the address we 51 are trying to lookup is local, for instance a web proxy */ 52 struct hostent *he = gethostbyname(address); 53 if(he) { 54 unsigned char *p = (unsigned char*)he->h_addr; 55 ip->s_addr = (p[0] << 24) | (p[1] << 16) | (p[2] << 8) | p[3]; 56 } else { 57 return -1; 58 } 59 } 60 return 0; 61 } 62 63 static int 64 setup_int(const char *proxy_host, short proxy_port, 65 const char *dns_host, short dns_port, 66 const char *dns_path) 67 { 68 memset(&dns_addr, 0, sizeof(dns_addr)); 69 if(dns_req) 70 free(dns_req); 71 dns_req = NULL; 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 if (asprintf(&dns_req, "http://%s:%d%s", dns_host, dns_port, dns_path) < 0) 77 return -1; 78 } else { 79 if(make_address(dns_host, &dns_addr.sin_addr) != 0) 80 return -1; 81 dns_addr.sin_port = htons(dns_port); 82 asprintf(&dns_req, "%s", dns_path); 83 } 84 dns_addr.sin_family = AF_INET; 85 return 0; 86 } 87 88 static void 89 split_spec(const char *spec, char **host, int *port, char **path, int def_port) 90 { 91 char *p; 92 *host = strdup(spec); 93 p = strchr(*host, ':'); 94 if(p) { 95 *p++ = '\0'; 96 if(sscanf(p, "%d", port) != 1) 97 *port = def_port; 98 } else 99 *port = def_port; 100 p = strchr(p ? p : *host, '/'); 101 if(p) { 102 if(path) 103 *path = strdup(p); 104 *p = '\0'; 105 }else 106 if(path) 107 *path = NULL; 108 } 109 110 111 ROKEN_LIB_FUNCTION int ROKEN_LIB_CALL 112 roken_gethostby_setup(const char *proxy_spec, const char *dns_spec) 113 { 114 char *proxy_host = NULL; 115 int proxy_port = 0; 116 char *dns_host, *dns_path; 117 int dns_port; 118 119 int ret = -1; 120 121 split_spec(dns_spec, &dns_host, &dns_port, &dns_path, 80); 122 if(dns_path == NULL) 123 goto out; 124 if(proxy_spec) 125 split_spec(proxy_spec, &proxy_host, &proxy_port, NULL, 80); 126 ret = setup_int(proxy_host, proxy_port, dns_host, dns_port, dns_path); 127 out: 128 free(proxy_host); 129 free(dns_host); 130 free(dns_path); 131 return ret; 132 } 133 134 135 /* Try to lookup a name or an ip-address using http as transport 136 mechanism. See the end of this file for an example program. */ 137 static struct hostent* 138 roken_gethostby(const char *hostname) 139 { 140 int s; 141 struct sockaddr_in addr; 142 char *request = NULL; 143 char buf[1024]; 144 int offset = 0; 145 int n; 146 char *p, *foo; 147 size_t len; 148 149 if(dns_addr.sin_family == 0) 150 return NULL; /* no configured host */ 151 addr = dns_addr; 152 if (asprintf(&request, "GET %s?%s HTTP/1.0\r\n\r\n", dns_req, hostname) < 0) 153 return NULL; 154 if(request == NULL) 155 return NULL; 156 s = socket(AF_INET, SOCK_STREAM, 0); 157 if(s < 0) { 158 free(request); 159 return NULL; 160 } 161 if(connect(s, (struct sockaddr*)&addr, sizeof(addr)) < 0) { 162 close(s); 163 free(request); 164 return NULL; 165 } 166 167 len = strlen(request); 168 if(write(s, request, len) != (ssize_t)len) { 169 close(s); 170 free(request); 171 return NULL; 172 } 173 free(request); 174 while(1) { 175 n = read(s, buf + offset, sizeof(buf) - offset); 176 if(n <= 0) 177 break; 178 offset += n; 179 } 180 buf[offset] = '\0'; 181 close(s); 182 p = strstr(buf, "\r\n\r\n"); /* find end of header */ 183 if(p) p += 4; 184 else return NULL; 185 foo = NULL; 186 p = strtok_r(p, " \t\r\n", &foo); 187 if(p == NULL) 188 return NULL; 189 { 190 /* make a hostent to return */ 191 #define MAX_ADDRS 16 192 static struct hostent he; 193 static char addrs[4 * MAX_ADDRS]; 194 static char *addr_list[MAX_ADDRS + 1]; 195 int num_addrs = 0; 196 197 he.h_name = p; 198 he.h_aliases = NULL; 199 he.h_addrtype = AF_INET; 200 he.h_length = 4; 201 202 while((p = strtok_r(NULL, " \t\r\n", &foo)) && num_addrs < MAX_ADDRS) { 203 struct in_addr ip; 204 inet_aton(p, &ip); 205 ip.s_addr = ntohl(ip.s_addr); 206 addr_list[num_addrs] = &addrs[num_addrs * 4]; 207 addrs[num_addrs * 4 + 0] = (ip.s_addr >> 24) & 0xff; 208 addrs[num_addrs * 4 + 1] = (ip.s_addr >> 16) & 0xff; 209 addrs[num_addrs * 4 + 2] = (ip.s_addr >> 8) & 0xff; 210 addrs[num_addrs * 4 + 3] = (ip.s_addr >> 0) & 0xff; 211 addr_list[++num_addrs] = NULL; 212 } 213 he.h_addr_list = addr_list; 214 return &he; 215 } 216 } 217 218 ROKEN_LIB_FUNCTION struct hostent* ROKEN_LIB_CALL 219 roken_gethostbyname(const char *hostname) 220 { 221 struct hostent *he; 222 he = gethostbyname(hostname); 223 if(he) 224 return he; 225 return roken_gethostby(hostname); 226 } 227 228 ROKEN_LIB_FUNCTION struct hostent* ROKEN_LIB_CALL 229 roken_gethostbyaddr(const void *addr, size_t len, int type) 230 { 231 struct in_addr a; 232 const char *p; 233 struct hostent *he; 234 he = gethostbyaddr(addr, len, type); 235 if(he) 236 return he; 237 if(type != AF_INET || len != 4) 238 return NULL; 239 p = addr; 240 a.s_addr = htonl((p[0] << 24) | (p[1] << 16) | (p[2] << 8) | p[3]); 241 return roken_gethostby(inet_ntoa(a)); 242 } 243 244 #if 0 245 246 /* this program can be used as a cgi `script' to lookup names and 247 ip-addresses */ 248 249 #include <stdio.h> 250 #include <stdlib.h> 251 #include <netdb.h> 252 #include <sys/param.h> 253 254 int 255 main(int argc, char **argv) 256 { 257 char *query = getenv("QUERY_STRING"); 258 char host[MAXHOSTNAMELEN]; 259 int i; 260 struct hostent *he; 261 262 printf("Content-type: text/plain\n\n"); 263 if(query == NULL) 264 exit(0); 265 he = gethostbyname(query); 266 strncpy(host, he->h_name, sizeof(host)); 267 host[sizeof(host) - 1] = '\0'; 268 he = gethostbyaddr(he->h_addr, he->h_length, AF_INET); 269 printf("%s\n", he->h_name); 270 for(i = 0; he->h_addr_list[i]; i++) { 271 struct in_addr ip; 272 unsigned char *p = (unsigned char*)he->h_addr_list[i]; 273 ip.s_addr = htonl((p[0] << 24) | (p[1] << 16) | (p[2] << 8) | p[3]); 274 printf("%s\n", inet_ntoa(ip)); 275 } 276 exit(0); 277 } 278 279 #endif 280