1 /* $NetBSD: roken_gethostby.c,v 1.2 2017/01/28 21:31:50 christos 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 if (asprintf(&dns_req, "%s", dns_path) < 0) 83 return -1; 84 } 85 dns_addr.sin_family = AF_INET; 86 return 0; 87 } 88 89 static void 90 split_spec(const char *spec, char **host, int *port, char **path, int def_port) 91 { 92 char *p; 93 *host = strdup(spec); 94 p = strchr(*host, ':'); 95 if(p) { 96 *p++ = '\0'; 97 if(sscanf(p, "%d", port) != 1) 98 *port = def_port; 99 } else 100 *port = def_port; 101 p = strchr(p ? p : *host, '/'); 102 if(p) { 103 if(path) 104 *path = strdup(p); 105 *p = '\0'; 106 }else 107 if(path) 108 *path = NULL; 109 } 110 111 112 ROKEN_LIB_FUNCTION int ROKEN_LIB_CALL 113 roken_gethostby_setup(const char *proxy_spec, const char *dns_spec) 114 { 115 char *proxy_host = NULL; 116 int proxy_port = 0; 117 char *dns_host, *dns_path; 118 int dns_port; 119 120 int ret = -1; 121 122 split_spec(dns_spec, &dns_host, &dns_port, &dns_path, 80); 123 if(dns_path == NULL) 124 goto out; 125 if(proxy_spec) 126 split_spec(proxy_spec, &proxy_host, &proxy_port, NULL, 80); 127 ret = setup_int(proxy_host, proxy_port, dns_host, dns_port, dns_path); 128 out: 129 free(proxy_host); 130 free(dns_host); 131 free(dns_path); 132 return ret; 133 } 134 135 136 /* Try to lookup a name or an ip-address using http as transport 137 mechanism. See the end of this file for an example program. */ 138 static struct hostent* 139 roken_gethostby(const char *hostname) 140 { 141 int s; 142 struct sockaddr_in addr; 143 char *request = NULL; 144 char buf[1024]; 145 int offset = 0; 146 int n; 147 char *p, *foo; 148 size_t len; 149 150 if(dns_addr.sin_family == 0) 151 return NULL; /* no configured host */ 152 addr = dns_addr; 153 if (asprintf(&request, "GET %s?%s HTTP/1.0\r\n\r\n", dns_req, hostname) < 0) 154 return NULL; 155 if(request == NULL) 156 return NULL; 157 s = socket(AF_INET, SOCK_STREAM, 0); 158 if(s < 0) { 159 free(request); 160 return NULL; 161 } 162 if(connect(s, (struct sockaddr*)&addr, sizeof(addr)) < 0) { 163 close(s); 164 free(request); 165 return NULL; 166 } 167 168 len = strlen(request); 169 if(write(s, request, len) != (ssize_t)len) { 170 close(s); 171 free(request); 172 return NULL; 173 } 174 free(request); 175 while(1) { 176 n = read(s, buf + offset, sizeof(buf) - offset); 177 if(n <= 0) 178 break; 179 offset += n; 180 } 181 buf[offset] = '\0'; 182 close(s); 183 p = strstr(buf, "\r\n\r\n"); /* find end of header */ 184 if(p) p += 4; 185 else return NULL; 186 foo = NULL; 187 p = strtok_r(p, " \t\r\n", &foo); 188 if(p == NULL) 189 return NULL; 190 { 191 /* make a hostent to return */ 192 #define MAX_ADDRS 16 193 static struct hostent he; 194 static char addrs[4 * MAX_ADDRS]; 195 static char *addr_list[MAX_ADDRS + 1]; 196 int num_addrs = 0; 197 198 he.h_name = p; 199 he.h_aliases = NULL; 200 he.h_addrtype = AF_INET; 201 he.h_length = 4; 202 203 while((p = strtok_r(NULL, " \t\r\n", &foo)) && num_addrs < MAX_ADDRS) { 204 struct in_addr ip; 205 inet_aton(p, &ip); 206 ip.s_addr = ntohl(ip.s_addr); 207 addr_list[num_addrs] = &addrs[num_addrs * 4]; 208 addrs[num_addrs * 4 + 0] = (ip.s_addr >> 24) & 0xff; 209 addrs[num_addrs * 4 + 1] = (ip.s_addr >> 16) & 0xff; 210 addrs[num_addrs * 4 + 2] = (ip.s_addr >> 8) & 0xff; 211 addrs[num_addrs * 4 + 3] = (ip.s_addr >> 0) & 0xff; 212 addr_list[++num_addrs] = NULL; 213 } 214 he.h_addr_list = addr_list; 215 return &he; 216 } 217 } 218 219 ROKEN_LIB_FUNCTION struct hostent* ROKEN_LIB_CALL 220 roken_gethostbyname(const char *hostname) 221 { 222 struct hostent *he; 223 he = gethostbyname(hostname); 224 if(he) 225 return he; 226 return roken_gethostby(hostname); 227 } 228 229 ROKEN_LIB_FUNCTION struct hostent* ROKEN_LIB_CALL 230 roken_gethostbyaddr(const void *addr, size_t len, int type) 231 { 232 struct in_addr a; 233 const char *p; 234 struct hostent *he; 235 he = gethostbyaddr(addr, len, type); 236 if(he) 237 return he; 238 if(type != AF_INET || len != 4) 239 return NULL; 240 p = addr; 241 a.s_addr = htonl((p[0] << 24) | (p[1] << 16) | (p[2] << 8) | p[3]); 242 return roken_gethostby(inet_ntoa(a)); 243 } 244 245 #if 0 246 247 /* this program can be used as a cgi `script' to lookup names and 248 ip-addresses */ 249 250 #include <stdio.h> 251 #include <stdlib.h> 252 #include <netdb.h> 253 #include <sys/param.h> 254 255 int 256 main(int argc, char **argv) 257 { 258 char *query = getenv("QUERY_STRING"); 259 char host[MAXHOSTNAMELEN]; 260 int i; 261 struct hostent *he; 262 263 printf("Content-type: text/plain\n\n"); 264 if(query == NULL) 265 exit(0); 266 he = gethostbyname(query); 267 strncpy(host, he->h_name, sizeof(host)); 268 host[sizeof(host) - 1] = '\0'; 269 he = gethostbyaddr(he->h_addr, he->h_length, AF_INET); 270 printf("%s\n", he->h_name); 271 for(i = 0; he->h_addr_list[i]; i++) { 272 struct in_addr ip; 273 unsigned char *p = (unsigned char*)he->h_addr_list[i]; 274 ip.s_addr = htonl((p[0] << 24) | (p[1] << 16) | (p[2] << 8) | p[3]); 275 printf("%s\n", inet_ntoa(ip)); 276 } 277 exit(0); 278 } 279 280 #endif 281