resolv/getnetnamadr.c

   1 /* Copyright (c) 1993 Carlos Leandro and Rui Salgueiro
   2  *      Dep. Matematica Universidade de Coimbra, Portugal, Europe
   3  *
   4  * Permission to use, copy, modify, and distribute this software for any
   5  * purpose with or without fee is hereby granted, provided that the above
   6  * copyright notice and this permission notice appear in all copies.
   7  */
   8 /*
   9  * Copyright (c) 1983, 1993
  10  *      The Regents of the University of California.  All rights reserved.
  11  *
  12  * Redistribution and use in source and binary forms, with or without
  13  * modification, are permitted provided that the following conditions
  14  * are met:
  15  * 1. Redistributions of source code must retain the above copyright
  16  *    notice, this list of conditions and the following disclaimer.
  17  * 2. Redistributions in binary form must reproduce the above copyright
  18  *    notice, this list of conditions and the following disclaimer in the
  19  *    documentation and/or other materials provided with the distribution.
  20  * 3. All advertising materials mentioning features or use of this software
  21  *    must display the following acknowledgement:
  22  *      This product includes software developed by the University of
  23  *      California, Berkeley and its contributors.
  24  * 4. Neither the name of the University nor the names of its contributors
  25  *    may be used to endorse or promote products derived from this software
  26  *    without specific prior written permission.
  27  *
  28  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  29  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  30  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  31  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  32  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  33  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  34  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  35  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  36  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  37  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  38  * SUCH DAMAGE.
  39  */
  40
  41 #if defined(LIBC_SCCS) && !defined(lint)
  42 static char sccsid[] = "@(#)getnetbyaddr.c      8.1 (Berkeley) 6/4/93";
  43 static char sccsid_[] = "from getnetnamadr.c    1.4 (Coimbra) 93/06/03";
  44 static char rcsid[] = "$Id$";
  45 #endif /* LIBC_SCCS and not lint */
  46
  47 #include <sys/param.h>
  48 #include <sys/socket.h>
  49 #include <netinet/in.h>
  50 #include <arpa/inet.h>
  51 #include <arpa/nameser.h>
  52
  53 #include <stdio.h>
  54 #include <netdb.h>
  55 #include <resolv.h>
  56 #include <ctype.h>
  57 #include <errno.h>
  58 #include <string.h>
  59
  60 extern int h_errno;
  61
  62 #if defined(mips) && defined(SYSTYPE_BSD43)
  63 extern int errno;
  64 #endif
  65
  66 struct netent *_getnetbyaddr __P((long net, int type));
  67 struct netent *_getnetbyname __P((const char *name));
  68
  69 #define BYADDR 0
  70 #define BYNAME 1
  71 #define MAXALIASES      35
  72
  73 #if PACKETSZ > 1024
  74 #define MAXPACKET       PACKETSZ
  75 #else
  76 #define MAXPACKET       1024
  77 #endif
  78
  79 typedef union {
  80         HEADER  hdr;
  81         u_char  buf[MAXPACKET];
  82 } querybuf;
  83
  84 typedef union {
  85         long    al;
  86         char    ac;
  87 } align;
  88
  89 static struct netent *
  90 getnetanswer(answer, anslen, net_i)
  91         querybuf *answer;
  92         int anslen;
  93         int net_i;
  94 {
  95
  96         register HEADER *hp;
  97         register u_char *cp;
  98         register int n;
  99         u_char *eom;
 100         int type, class, buflen, ancount, qdcount, haveanswer, i, nchar;
 101         char aux1[30], aux2[30], ans[30], *in, *st, *pauxt, *bp, **ap,
 102                 *paux1 = &aux1[0], *paux2 = &aux2[0], flag = 0;
 103 static  struct netent net_entry;
 104 static  char *net_aliases[MAXALIASES], netbuf[BUFSIZ+1];
 105
 106         /*
 107          * find first satisfactory answer
 108          *
 109          *      answer --> +------------+  ( MESSAGE )
 110          *                 |   Header   |
 111          *                 +------------+
 112          *                 |  Question  | the question for the name server
 113          *                 +------------+
 114          *                 |   Answer   | RRs answering the question
 115          *                 +------------+
 116          *                 | Authority  | RRs pointing toward an authority
 117          *                 | Additional | RRs holding additional information
 118          *                 +------------+
 119          */
 120         eom = answer->buf + anslen;
 121         hp = &answer->hdr;
 122         ancount = ntohs(hp->ancount); /* #/records in the answer section */
 123         qdcount = ntohs(hp->qdcount); /* #/entries in the question section */
 124         bp = netbuf;
 125         buflen = sizeof(netbuf);
 126         cp = answer->buf + HFIXEDSZ;
 127         if (!qdcount) {
 128                 if (hp->aa)
 129                         h_errno = HOST_NOT_FOUND;
 130                 else
 131                         h_errno = TRY_AGAIN;
 132                 return (NULL);
 133         }
 134         while (qdcount-- > 0)
 135                 cp += __dn_skipname(cp, eom) + QFIXEDSZ;
 136         ap = net_aliases;
 137         *ap = NULL;
 138         net_entry.n_aliases = net_aliases;
 139         haveanswer = 0;
 140         while (--ancount >= 0 && cp < eom) {
 141                 n = dn_expand(answer->buf, eom, cp, bp, buflen);
 142                 if (n < 0)
 143                         break;
 144                 cp += n;
 145                 ans[0] = '\0';
 146                 (void)strcpy(&ans[0], bp);
 147                 GETSHORT(type, cp);
 148                 GETSHORT(class, cp);
 149                 cp += INT32SZ;          /* TTL */
 150                 GETSHORT(n, cp);
 151                 if (class == C_IN && type == T_PTR) {
 152                         n = dn_expand(answer->buf, eom, cp, bp, buflen);
 153                         if (n < 0) {
 154                                 cp += n;
 155                                 return (NULL);
 156                         }
 157                         cp += n;
 158                         *ap++ = bp;
 159                         bp += strlen(bp) + 1;
 160                         net_entry.n_addrtype =
 161                                 (class == C_IN) ? AF_INET : AF_UNSPEC;
 162                         haveanswer++;
 163                 }
 164         }
 165         if (haveanswer) {
 166                 *ap = NULL;
 167                 switch (net_i) {
 168                 case BYADDR:
 169                         net_entry.n_name = *net_entry.n_aliases;
 170                         net_entry.n_net = 0L;
 171                         break;
 172                 case BYNAME:
 173                         in = *net_entry.n_aliases;
 174                         net_entry.n_name = &ans[0];
 175                         aux2[0] = '\0';
 176                         for (i = 0; i < 4; i++) {
 177                                 for (st = in, nchar = 0;
 178                                      *st != '.';
 179                                      st++, nchar++)
 180                                         ;
 181                                 if (nchar != 1 || *in != '0' || flag) {
 182                                         flag = 1;
 183                                         (void)strncpy(paux1,
 184                                                       (i==0) ? in : in-1,
 185                                                       (i==0) ?nchar : nchar+1);
 186                                         paux1[(i==0) ? nchar : nchar+1] = '\0';
 187                                         pauxt = paux2;
 188                                         paux2 = strcat(paux1, paux2);
 189                                         paux1 = pauxt;
 190                                 }
 191                                 in = ++st;
 192                         }
 193                         net_entry.n_net = inet_network(paux2);
 194                         break;
 195                 }
 196                 net_entry.n_aliases++;
 197                 return (&net_entry);
 198         }
 199         h_errno = TRY_AGAIN;
 200         return (NULL);
 201 }
 202
 203 struct netent *
 204 getnetbyaddr(net, net_type)
 205         register long net;
 206         register int net_type;
 207 {
 208         unsigned int netbr[4];
 209         int nn, anslen;
 210         querybuf buf;
 211         char qbuf[MAXDNAME];
 212         unsigned long net2;
 213         struct netent *net_entry;
 214
 215         if (net_type != AF_INET)
 216                 return (_getnetbyaddr(net, net_type));
 217
 218         for (nn = 4, net2 = net; net2; net2 >>= 8)
 219                 netbr[--nn] = net2 & 0xff;
 220         switch (nn) {
 221         case 3:         /* Class A */
 222                 sprintf(qbuf, "0.0.0.%u.in-addr.arpa", netbr[3]);
 223                 break;
 224         case 2:         /* Class B */
 225                 sprintf(qbuf, "0.0.%u.%u.in-addr.arpa", netbr[3], netbr[2]);
 226                 break;
 227         case 1:         /* Class C */
 228                 sprintf(qbuf, "0.%u.%u.%u.in-addr.arpa", netbr[3], netbr[2],
 229                     netbr[1]);
 230                 break;
 231         case 0:         /* Class D - E */
 232                 sprintf(qbuf, "%u.%u.%u.%u.in-addr.arpa", netbr[3], netbr[2],
 233                     netbr[1], netbr[0]);
 234                 break;
 235         }
 236         anslen = res_query(qbuf, C_IN, T_PTR, (u_char *)&buf, sizeof(buf));
 237         if (anslen < 0) {
 238 #ifdef DEBUG
 239                 if (_res.options & RES_DEBUG)
 240                         printf("res_query failed\n");
 241 #endif
 242                 if (errno == ECONNREFUSED)
 243                         return (_getnetbyaddr(net, net_type));
 244                 return (NULL);
 245         }
 246         net_entry = getnetanswer(&buf, anslen, BYADDR);
 247         if (net_entry) {
 248                 unsigned u_net = net;   /* maybe net should be unsigned ? */
 249
 250                 /* Strip trailing zeros */
 251                 while ((u_net & 0xff) == 0 && u_net != 0)
 252                         u_net >>= 8;
 253                 net_entry->n_net = u_net;
 254                 return (net_entry);
 255         }
 256         return (_getnetbyaddr(net, net_type));
 257 }
 258
 259 struct netent *
 260 getnetbyname(net)
 261         register const char *net;
 262 {
 263         int anslen;
 264         querybuf buf;
 265         char qbuf[MAXDNAME];
 266         struct netent *net_entry;
 267
 268         if ((_res.options & RES_INIT) == 0 && res_init() == -1) {
 269                 h_errno = NETDB_INTERNAL;
 270                 return (NULL);
 271         }
 272         strcpy(&qbuf[0], net);
 273         anslen = res_search(qbuf, C_IN, T_PTR, (u_char *)&buf, sizeof(buf));
 274         if (anslen < 0) {
 275 #ifdef DEBUG
 276                 if (_res.options & RES_DEBUG)
 277                         printf("res_query failed\n");
 278 #endif
 279                 if (errno == ECONNREFUSED)
 280                         return (_getnetbyname(net));
 281                 return (_getnetbyname(net));
 282         }
 283         net_entry = getnetanswer(&buf, anslen, BYNAME);
 284         if (net_entry)
 285                 return (net_entry);
 286         return (_getnetbyname(net));
 287 }