lib/libc/net/getnetbydns.c

   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. Neither the name of the University nor the names of its contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  * -
  29  * Portions Copyright (c) 1993 by Digital Equipment Corporation.
  30  *
  31  * Permission to use, copy, modify, and distribute this software for any
  32  * purpose with or without fee is hereby granted, provided that the above
  33  * copyright notice and this permission notice appear in all copies, and that
  34  * the name of Digital Equipment Corporation not be used in advertising or
  35  * publicity pertaining to distribution of the document or software without
  36  * specific, written prior permission.
  37  *
  38  * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
  39  * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
  40  * OF MERCHANTABILITY AND FITNESS.   IN NO EVENT SHALL DIGITAL EQUIPMENT
  41  * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
  42  * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
  43  * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
  44  * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
  45  * SOFTWARE.
  46  * -
  47  * --Copyright--
  48  *
  49  * @(#)gethostnamadr.c  8.1 (Berkeley) 6/4/93
  50  * $FreeBSD: src/lib/libc/net/getnetbydns.c,v 1.13.2.4 2002/10/11 11:07:13 ume Exp $
  51  * $DragonFly: src/lib/libc/net/getnetbydns.c,v 1.5 2005/11/13 02:04:47 swildner Exp $
  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 #include <sys/param.h>
  62 #include <sys/socket.h>
  63 #include <netinet/in.h>
  64 #include <arpa/inet.h>
  65 #include <arpa/nameser.h>
  66
  67 #include <stdio.h>
  68 #include <stdlib.h>
  69 #include <netdb.h>
  70 #include <resolv.h>
  71 #include <ctype.h>
  72 #include <string.h>
  73 #include <unistd.h>
  74 #include <syslog.h>
  75
  76 #include "res_config.h"
  77
  78 extern int h_errno;
  79
  80 #define BYADDR 0
  81 #define BYNAME 1
  82 #define MAXALIASES      35
  83
  84 #define MAXPACKET       (64*1024)
  85
  86 typedef union {
  87         HEADER  hdr;
  88         u_char  buf[MAXPACKET];
  89 } querybuf;
  90
  91 typedef union {
  92         long    al;
  93         char    ac;
  94 } align;
  95
  96 static struct netent *
  97 getnetanswer(querybuf *answer, int anslen, int net_i)
  98 {
  99
 100         HEADER *hp;
 101         u_char *cp;
 102         int n;
 103         u_char *eom;
 104         int type, class, buflen, ancount, qdcount, haveanswer, i, nchar;
 105         char aux1[MAXHOSTNAMELEN], aux2[MAXHOSTNAMELEN], ans[MAXHOSTNAMELEN];
 106         char *in, *st, *pauxt, *bp, **ap;
 107         char *paux1 = &aux1[0], *paux2 = &aux2[0], flag = 0;
 108 static  struct netent net_entry;
 109 static  char *net_aliases[MAXALIASES], netbuf[PACKETSZ];
 110
 111         /*
 112          * find first satisfactory answer
 113          *
 114          *      answer --> +------------+  ( MESSAGE )
 115          *                 |   Header   |
 116          *                 +------------+
 117          *                 |  Question  | the question for the name server
 118          *                 +------------+
 119          *                 |   Answer   | RRs answering the question
 120          *                 +------------+
 121          *                 | Authority  | RRs pointing toward an authority
 122          *                 | Additional | RRs holding additional information
 123          *                 +------------+
 124          */
 125         eom = answer->buf + anslen;
 126         hp = &answer->hdr;
 127         ancount = ntohs(hp->ancount); /* #/records in the answer section */
 128         qdcount = ntohs(hp->qdcount); /* #/entries in the question section */
 129         bp = netbuf;
 130         buflen = sizeof(netbuf);
 131         cp = answer->buf + HFIXEDSZ;
 132         if (!qdcount) {
 133                 if (hp->aa)
 134                         h_errno = HOST_NOT_FOUND;
 135                 else
 136                         h_errno = TRY_AGAIN;
 137                 return (NULL);
 138         }
 139         while (qdcount-- > 0)
 140                 cp += __dn_skipname(cp, eom) + QFIXEDSZ;
 141         ap = net_aliases;
 142         *ap = NULL;
 143         net_entry.n_aliases = net_aliases;
 144         haveanswer = 0;
 145         while (--ancount >= 0 && cp < eom) {
 146                 n = dn_expand(answer->buf, eom, cp, bp, buflen);
 147                 if ((n < 0) || !res_dnok(bp))
 148                         break;
 149                 cp += n;
 150                 ans[0] = '\0';
 151                 strncpy(&ans[0], bp, sizeof(ans) - 1);
 152                 ans[sizeof(ans) - 1] = '\0';
 153                 GETSHORT(type, cp);
 154                 GETSHORT(class, cp);
 155                 cp += INT32SZ;          /* TTL */
 156                 GETSHORT(n, cp);
 157                 if (class == C_IN && type == T_PTR) {
 158                         n = dn_expand(answer->buf, eom, cp, bp, buflen);
 159                         if ((n < 0) || !res_hnok(bp)) {
 160                                 cp += n;
 161                                 return (NULL);
 162                         }
 163                         cp += n;
 164                         *ap++ = bp;
 165                         n = strlen(bp) + 1;
 166                         bp += n;
 167                         buflen -= n;
 168                         net_entry.n_addrtype =
 169                                 (class == C_IN) ? AF_INET : AF_UNSPEC;
 170                         haveanswer++;
 171                 }
 172         }
 173         if (haveanswer) {
 174                 *ap = NULL;
 175                 switch (net_i) {
 176                 case BYADDR:
 177                         net_entry.n_name = *net_entry.n_aliases;
 178                         net_entry.n_net = 0L;
 179                         break;
 180                 case BYNAME:
 181                         in = *net_entry.n_aliases;
 182                         net_entry.n_name = &ans[0];
 183                         aux2[0] = '\0';
 184                         for (i = 0; i < 4; i++) {
 185                                 for (st = in, nchar = 0;
 186                                      *st != '.';
 187                                      st++, nchar++)
 188                                         ;
 189                                 if (nchar != 1 || *in != '0' || flag) {
 190                                         flag = 1;
 191                                         strncpy(paux1, (i==0) ? in : in-1,
 192                                                 (i==0) ? nchar : nchar+1);
 193                                         paux1[(i==0) ? nchar : nchar+1] = '\0';
 194                                         pauxt = paux2;
 195                                         paux2 = strcat(paux1, paux2);
 196                                         paux1 = pauxt;
 197                                 }
 198                                 in = ++st;
 199                         }
 200                         net_entry.n_net = inet_network(paux2);
 201                         break;
 202                 }
 203                 net_entry.n_aliases++;
 204                 return (&net_entry);
 205         }
 206         h_errno = TRY_AGAIN;
 207         return (NULL);
 208 }
 209
 210 struct netent *
 211 _getnetbydnsaddr(unsigned long net, int net_type)
 212 {
 213         unsigned int netbr[4];
 214         int nn, anslen;
 215         querybuf *buf;
 216         char qbuf[MAXDNAME];
 217         unsigned long net2;
 218         struct netent *net_entry;
 219
 220         if (net_type != AF_INET)
 221                 return (NULL);
 222
 223         for (nn = 4, net2 = net; net2; net2 >>= 8)
 224                 netbr[--nn] = net2 & 0xff;
 225         switch (nn) {
 226         case 3:         /* Class A */
 227                 sprintf(qbuf, "0.0.0.%u.in-addr.arpa", netbr[3]);
 228                 break;
 229         case 2:         /* Class B */
 230                 sprintf(qbuf, "0.0.%u.%u.in-addr.arpa", netbr[3], netbr[2]);
 231                 break;
 232         case 1:         /* Class C */
 233                 sprintf(qbuf, "0.%u.%u.%u.in-addr.arpa", netbr[3], netbr[2],
 234                     netbr[1]);
 235                 break;
 236         case 0:         /* Class D - E */
 237                 sprintf(qbuf, "%u.%u.%u.%u.in-addr.arpa", netbr[3], netbr[2],
 238                     netbr[1], netbr[0]);
 239                 break;
 240         }
 241         if ((buf = malloc(sizeof(*buf))) == NULL) {
 242                 h_errno = NETDB_INTERNAL;
 243                 return (NULL);
 244         }
 245         anslen = res_query(qbuf, C_IN, T_PTR, (u_char *)buf, sizeof(*buf));
 246         if (anslen < 0) {
 247                 free(buf);
 248 #ifdef DEBUG
 249                 if (_res.options & RES_DEBUG)
 250                         printf("res_search failed\n");
 251 #endif
 252                 return (NULL);
 253         } else if (anslen > sizeof(*buf)) {
 254                 free(buf);
 255 #ifdef DEBUG
 256                 if (_res.options & RES_DEBUG)
 257                         printf("res_search static buffer too small\n");
 258 #endif
 259                 return (NULL);
 260         }
 261         net_entry = getnetanswer(buf, anslen, BYADDR);
 262         free(buf);
 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
 275 struct netent *
 276 _getnetbydnsname(const char *net)
 277 {
 278         int anslen;
 279         querybuf *buf;
 280         char qbuf[MAXDNAME];
 281         struct netent *net_entry;
 282
 283         if ((_res.options & RES_INIT) == 0 && res_init() == -1) {
 284                 h_errno = NETDB_INTERNAL;
 285                 return (NULL);
 286         }
 287         if ((buf = malloc(sizeof(*buf))) == NULL) {
 288                 h_errno = NETDB_INTERNAL;
 289                 return (NULL);
 290         }
 291         strncpy(qbuf, net, sizeof(qbuf) - 1);
 292         qbuf[sizeof(qbuf) - 1] = '\0';
 293         anslen = res_search(qbuf, C_IN, T_PTR, (u_char *)buf, sizeof(*buf));
 294         if (anslen < 0) {
 295                 free(buf);
 296 #ifdef DEBUG
 297                 if (_res.options & RES_DEBUG)
 298                         printf("res_search failed\n");
 299 #endif
 300                 return (NULL);
 301         } else if (anslen > sizeof(*buf)) {
 302                 free(buf);
 303 #ifdef DEBUG
 304                 if (_res.options & RES_DEBUG)
 305                         printf("res_search static buffer too small\n");
 306 #endif
 307                 return (NULL);
 308         }
 309         net_entry = getnetanswer(buf, anslen, BYNAME);
 310         free(buf);
 311         return net_entry;
 312 }
 313
 314 void
 315 _setnetdnsent(int stayopen)
 316 {
 317         if (stayopen)
 318                 _res.options |= RES_STAYOPEN | RES_USEVC;
 319 }
 320
 321 void
 322 _endnetdnsent(void)
 323 {
 324         _res.options &= ~(RES_STAYOPEN | RES_USEVC);
 325         res_close();
 326 }