getnetbydns.c revision 32299
1/*- 2 * Copyright (c) 1985, 1988, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed by the University of 16 * California, Berkeley and its contributors. 17 * 4. Neither the name of the University 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 REGENTS 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 REGENTS 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 * Portions Copyright (c) 1993 by Digital Equipment Corporation. 34 * 35 * Permission to use, copy, modify, and distribute this software for any 36 * purpose with or without fee is hereby granted, provided that the above 37 * copyright notice and this permission notice appear in all copies, and that 38 * the name of Digital Equipment Corporation not be used in advertising or 39 * publicity pertaining to distribution of the document or software without 40 * specific, written prior permission. 41 * 42 * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL 43 * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES 44 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL DIGITAL EQUIPMENT 45 * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL 46 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR 47 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS 48 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS 49 * SOFTWARE. 50 * - 51 * --Copyright-- 52 */ 53/* Portions Copyright (c) 1993 Carlos Leandro and Rui Salgueiro 54 * Dep. Matematica Universidade de Coimbra, Portugal, Europe 55 * 56 * Permission to use, copy, modify, and distribute this software for any 57 * purpose with or without fee is hereby granted, provided that the above 58 * copyright notice and this permission notice appear in all copies. 59 */ 60 61#if defined(LIBC_SCCS) && !defined(lint) 62static char sccsid[] = "@(#)gethostnamadr.c 8.1 (Berkeley) 6/4/93"; 63static char rcsid[] = "$Id: getnetbydns.c,v 1.11 1997/06/27 08:22:01 peter Exp $"; 64#endif /* LIBC_SCCS and not lint */ 65 66#include <sys/param.h> 67#include <sys/socket.h> 68#include <netinet/in.h> 69#include <arpa/inet.h> 70#include <arpa/nameser.h> 71 72#include <stdio.h> 73#include <netdb.h> 74#include <resolv.h> 75#include <ctype.h> 76#include <errno.h> 77#include <string.h> 78#include <unistd.h> 79#include <syslog.h> 80 81#include "res_config.h" 82 83extern int h_errno; 84 85#define BYADDR 0 86#define BYNAME 1 87#define MAXALIASES 35 88 89#if PACKETSZ > 1024 90#define MAXPACKET PACKETSZ 91#else 92#define MAXPACKET 1024 93#endif 94 95typedef union { 96 HEADER hdr; 97 u_char buf[MAXPACKET]; 98} querybuf; 99 100typedef union { 101 long al; 102 char ac; 103} align; 104 105static struct netent * 106getnetanswer(answer, anslen, net_i) 107 querybuf *answer; 108 int anslen; 109 int net_i; 110{ 111 112 register HEADER *hp; 113 register u_char *cp; 114 register int n; 115 u_char *eom; 116 int type, class, buflen, ancount, qdcount, haveanswer, i, nchar; 117 char aux1[MAXHOSTNAMELEN], aux2[MAXHOSTNAMELEN], ans[MAXHOSTNAMELEN]; 118 char *in, *st, *pauxt, *bp, **ap; 119 char *paux1 = &aux1[0], *paux2 = &aux2[0], flag = 0; 120static struct netent net_entry; 121static char *net_aliases[MAXALIASES], netbuf[PACKETSZ]; 122 123 /* 124 * find first satisfactory answer 125 * 126 * answer --> +------------+ ( MESSAGE ) 127 * | Header | 128 * +------------+ 129 * | Question | the question for the name server 130 * +------------+ 131 * | Answer | RRs answering the question 132 * +------------+ 133 * | Authority | RRs pointing toward an authority 134 * | Additional | RRs holding additional information 135 * +------------+ 136 */ 137 eom = answer->buf + anslen; 138 hp = &answer->hdr; 139 ancount = ntohs(hp->ancount); /* #/records in the answer section */ 140 qdcount = ntohs(hp->qdcount); /* #/entries in the question section */ 141 bp = netbuf; 142 buflen = sizeof(netbuf); 143 cp = answer->buf + HFIXEDSZ; 144 if (!qdcount) { 145 if (hp->aa) 146 h_errno = HOST_NOT_FOUND; 147 else 148 h_errno = TRY_AGAIN; 149 return (NULL); 150 } 151 while (qdcount-- > 0) 152 cp += __dn_skipname(cp, eom) + QFIXEDSZ; 153 ap = net_aliases; 154 *ap = NULL; 155 net_entry.n_aliases = net_aliases; 156 haveanswer = 0; 157 while (--ancount >= 0 && cp < eom) { 158 n = dn_expand(answer->buf, eom, cp, bp, buflen); 159 if ((n < 0) || !res_dnok(bp)) 160 break; 161 cp += n; 162 ans[0] = '\0'; 163 (void)strncpy(&ans[0], bp, sizeof(ans) - 1); 164 ans[sizeof(ans) - 1] = '\0'; 165 GETSHORT(type, cp); 166 GETSHORT(class, cp); 167 cp += INT32SZ; /* TTL */ 168 GETSHORT(n, cp); 169 if (class == C_IN && type == T_PTR) { 170 n = dn_expand(answer->buf, eom, cp, bp, buflen); 171 if ((n < 0) || !res_hnok(bp)) { 172 cp += n; 173 return (NULL); 174 } 175 cp += n; 176 *ap++ = bp; 177 bp += strlen(bp) + 1; 178 net_entry.n_addrtype = 179 (class == C_IN) ? AF_INET : AF_UNSPEC; 180 haveanswer++; 181 } 182 } 183 if (haveanswer) { 184 *ap = NULL; 185 switch (net_i) { 186 case BYADDR: 187 net_entry.n_name = *net_entry.n_aliases; 188 net_entry.n_net = 0L; 189 break; 190 case BYNAME: 191 in = *net_entry.n_aliases; 192 net_entry.n_name = &ans[0]; 193 aux2[0] = '\0'; 194 for (i = 0; i < 4; i++) { 195 for (st = in, nchar = 0; 196 *st != '.'; 197 st++, nchar++) 198 ; 199 if (nchar != 1 || *in != '0' || flag) { 200 flag = 1; 201 (void)strncpy(paux1, 202 (i==0) ? in : in-1, 203 (i==0) ?nchar : nchar+1); 204 paux1[(i==0) ? nchar : nchar+1] = '\0'; 205 pauxt = paux2; 206 paux2 = strcat(paux1, paux2); 207 paux1 = pauxt; 208 } 209 in = ++st; 210 } 211 net_entry.n_net = inet_network(paux2); 212 break; 213 } 214 net_entry.n_aliases++; 215 return (&net_entry); 216 } 217 h_errno = TRY_AGAIN; 218 return (NULL); 219} 220 221struct netent * 222_getnetbydnsaddr(net, net_type) 223 register unsigned long net; 224 register int net_type; 225{ 226 unsigned int netbr[4]; 227 int nn, anslen; 228 querybuf buf; 229 char qbuf[MAXDNAME]; 230 unsigned long net2; 231 struct netent *net_entry; 232 233 if (net_type != AF_INET) 234 return (NULL); 235 236 for (nn = 4, net2 = net; net2; net2 >>= 8) 237 netbr[--nn] = net2 & 0xff; 238 switch (nn) { 239 case 3: /* Class A */ 240 sprintf(qbuf, "0.0.0.%u.in-addr.arpa", netbr[3]); 241 break; 242 case 2: /* Class B */ 243 sprintf(qbuf, "0.0.%u.%u.in-addr.arpa", netbr[3], netbr[2]); 244 break; 245 case 1: /* Class C */ 246 sprintf(qbuf, "0.%u.%u.%u.in-addr.arpa", netbr[3], netbr[2], 247 netbr[1]); 248 break; 249 case 0: /* Class D - E */ 250 sprintf(qbuf, "%u.%u.%u.%u.in-addr.arpa", netbr[3], netbr[2], 251 netbr[1], netbr[0]); 252 break; 253 } 254 anslen = res_query(qbuf, C_IN, T_PTR, (u_char *)&buf, sizeof(buf)); 255 if (anslen < 0) { 256#ifdef DEBUG 257 if (_res.options & RES_DEBUG) 258 printf("res_query failed\n"); 259#endif 260 return (NULL); 261 } 262 net_entry = getnetanswer(&buf, anslen, BYADDR); 263 if (net_entry) { 264 unsigned u_net = net; /* maybe net should be unsigned ? */ 265 266 /* Strip trailing zeros */ 267 while ((u_net & 0xff) == 0 && u_net != 0) 268 u_net >>= 8; 269 net_entry->n_net = u_net; 270 return (net_entry); 271 } 272 return (NULL); 273} 274 275struct netent * 276_getnetbydnsname(net) 277 register const char *net; 278{ 279 int anslen; 280 querybuf buf; 281 char qbuf[MAXDNAME]; 282 283 if ((_res.options & RES_INIT) == 0 && res_init() == -1) { 284 h_errno = NETDB_INTERNAL; 285 return (NULL); 286 } 287 strncpy(qbuf, net, sizeof(qbuf) - 1); 288 qbuf[sizeof(qbuf) - 1] = '\0'; 289 anslen = res_search(qbuf, C_IN, T_PTR, (u_char *)&buf, sizeof(buf)); 290 if (anslen < 0) { 291#ifdef DEBUG 292 if (_res.options & RES_DEBUG) 293 printf("res_query failed\n"); 294#endif 295 return (NULL); 296 } 297 return getnetanswer(&buf, anslen, BYNAME); 298} 299 300void 301_setnetdnsent(stayopen) 302 int stayopen; 303{ 304 if (stayopen) 305 _res.options |= RES_STAYOPEN | RES_USEVC; 306} 307 308void 309_endnetdnsent() 310{ 311 _res.options &= ~(RES_STAYOPEN | RES_USEVC); 312 res_close(); 313} 314