resolv/getnetnamadr.c

   1 /* Copyright (c) 1993 Carlos Leandro and Rui Salgueiro
   2  *      Dep. Matematica Universidade de Coimbra, Portugal, Europe
   3  */
   4 /*
   5  * Copyright (c) 1983 Regents of the University of California.
   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  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  * 3. All advertising materials mentioning features or use of this software
  17  *    must display the following acknowledgement:
  18  *      This product includes software developed by the University of
  19  *      California, Berkeley and its contributors.
  20  * 4. Neither the name of the University nor the names of its contributors
  21  *    may be used to endorse or promote products derived from this software
  22  *    without specific prior written permission.
  23  *
  24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  34  * SUCH DAMAGE.
  35  */
  36
  37 #if defined(LIBC_SCCS) && !defined(lint)
  38 static char sccsid[] = "@(#)getnetnamadr.c      1.4 (Coimbra) 93/06/03";
  39 static char rcsid[] = "$Id$";
  40 #endif /* LIBC_SCCS and not lint */
  41
  42 #include <sys/param.h>
  43 #include <sys/socket.h>
  44 #include <netinet/in.h>
  45 #include <arpa/inet.h>
  46 #include <arpa/nameser.h>
  47
  48 #include <stdio.h>
  49 #include <netdb.h>
  50 #include <resolv.h>
  51 #include <ctype.h>
  52 #include <errno.h>
  53 #include <string.h>
  54
  55 extern int h_errno;
  56
  57 #if defined(mips) && defined(SYSTYPE_BSD43)
  58 extern int errno;
  59 #endif
  60
  61 struct netent *_getnetbyaddr __P((long net, int type));
  62 #if defined(sun)
  63 struct netent *_getnetbyname __P((char *name));
  64 #else
  65 struct netent *_getnetbyname __P((const char *name));
  66 #endif
  67
  68 #define BYADDR 0
  69 #define BYNAME 1
  70 #define MAXALIASES      35
  71
  72 #if PACKETSZ > 1024
  73 #define MAXPACKET       PACKETSZ
  74 #else
  75 #define MAXPACKET       1024
  76 #endif
  77
  78 typedef union {
  79         HEADER  hdr;
  80         u_char  buf[MAXPACKET];
  81 } querybuf;
  82
  83 typedef union {
  84         long    al;
  85         char    ac;
  86 } align;
  87
  88 static struct netent *
  89 getnetanswer(answer, anslen, net_i)
  90         querybuf *answer;
  91         int anslen;
  92         int net_i;
  93 {
  94
  95         register HEADER *hp;
  96         register u_char *cp;
  97         register int    n;
  98         u_char          *eom;
  99         int             type, class, buflen, ancount, qdcount,
 100                         haveanswer, i, nchar,
 101                         getclass = C_ANY,
 102                         net_length = 0;
 103         char            aux1[30], aux2[30], ans[30],
 104                         *in, *st, *pauxt, *bp, **ap,
 105                         *paux1 = &aux1[0],
 106                         *paux2 = &aux2[0],
 107                         flag = 0;
 108 static  struct netent   net_entry;
 109 static  char            *net_aliases[MAXALIASES],
 110                         netbuf[BUFSIZ+1];
 111
 112         /*
 113          * find first satisfactory answer
 114          *
 115          *      answer --> +------------+  ( MESSAGE )
 116          *                 |   Header   |
 117          *                 +------------+
 118          *                 |  Question  | the question for the name server
 119          *                 +------------+
 120          *                 |   Answer   | RRs answering the question
 121          *                 +------------+
 122          *                 | Authority  | RRs pointing toward an authority
 123          *                 | Additional | RRs holding additional information
 124          *                 +------------+
 125          */
 126         eom = answer->buf + anslen;
 127         hp = &answer->hdr;
 128         ancount = ntohs(hp->ancount); /* #/records in the answer section */
 129         qdcount = ntohs(hp->qdcount); /* #/entries in the question section */
 130         bp = netbuf;
 131         buflen = sizeof(netbuf);
 132         cp = answer->buf + HFIXEDSZ;
 133         if (!qdcount) {
 134                 if (hp->aa)
 135                         h_errno = HOST_NOT_FOUND;
 136                 else
 137                         h_errno = TRY_AGAIN;
 138
 139                 return ((struct netent *) NULL);
 140         }
 141         while (qdcount-- > 0){
 142                 cp += __dn_skipname(cp, eom) + QFIXEDSZ;
 143         }
 144         ap = net_aliases;
 145         *ap = NULL;
 146         net_entry.n_aliases = net_aliases;
 147         haveanswer = 0;
 148         while (--ancount >= 0 && cp < eom) {
 149                 n = dn_expand(answer->buf, eom, cp, bp, buflen);
 150                 if (n < 0)
 151                         break;
 152                 cp += n;
 153                 ans[0] = '\0';
 154                 (void)strcpy(&ans[0], bp);
 155                 GETSHORT(type, cp);
 156                 GETSHORT(class, cp);
 157                 cp += INT32SZ;          /* TTL */
 158                 GETSHORT(n, cp);
 159                 if (class == C_IN && type == T_PTR) {
 160                         n = dn_expand(answer->buf, eom, cp, bp, buflen);
 161                         if (n < 0) {
 162                                 cp += n;
 163                                 return (NULL);
 164                         }
 165                         cp += n;
 166                         *ap++ = bp;
 167                         bp += (strlen(bp) + 1);
 168                         net_entry.n_addrtype = (class == C_IN)
 169                                                 ? AF_INET
 170                                                 : AF_UNSPEC;
 171                         haveanswer++;
 172                 }
 173         }
 174         if (haveanswer) {
 175                 *ap = NULL;
 176                 switch (net_i) {
 177                    case BYADDR :
 178                         net_entry.n_name = *net_entry.n_aliases;
 179                         net_entry.n_net = 0L;
 180                         break;
 181                    case BYNAME :
 182                         in = *net_entry.n_aliases;
 183                         net_entry.n_name = &ans[0];
 184                         aux2[0] = '\0';
 185                         for (i = 0;  i < 4;  i++) {
 186                                 for (st = in, nchar = 0;
 187                                      *st != '.';
 188                                      st++, nchar++)
 189                                         ;
 190                                 if (nchar != 1 || *in != '0' || flag) {
 191                                         flag = 1;
 192                                         (void)strncpy(paux1,
 193                                                       (i==0) ?in :in-1,
 194                                                       (i==0) ?nchar :nchar+1);
 195                                         paux1[(i==0) ?nchar :nchar+1] = '\0';
 196                                         pauxt = paux2;
 197                                         paux2 = strcat(paux1, paux2);
 198                                         paux1 = pauxt;
 199                                 }
 200                                 in = ++st;
 201                         }
 202                         net_entry.n_net = inet_network(paux2);
 203                 }
 204                 net_entry.n_aliases++;
 205                 return (&net_entry);
 206         } else {
 207                 h_errno = TRY_AGAIN;
 208                 return ((struct netent *) NULL);
 209         }
 210 }
 211
 212 struct netent *
 213 getnetbyaddr(net, net_type)
 214         register long net;
 215         register int net_type;
 216 {
 217         unsigned int    netbr[4];
 218         int             nn, anslen;
 219         querybuf        buf;
 220         char            qbuf[MAXDNAME];
 221         unsigned long   net2;
 222         struct netent   *net_entry;
 223
 224         if (net_type != AF_INET)
 225                 return (_getnetbyaddr(net, net_type));
 226
 227         for (nn = 4, net2 = net;  net2;  net2 >>= 8) {
 228                 netbr[--nn] = net2 & 0xff;
 229         }
 230         switch (nn) {
 231                 case 3:         /* Class A */
 232                         (void)sprintf(qbuf, "0.0.0.%u.in-addr.arpa",
 233                                       netbr[3]);
 234                         break;
 235                 case 2:         /* Class B */
 236                         (void)sprintf(qbuf, "0.0.%u.%u.in-addr.arpa",
 237                                       netbr[3], netbr[2]);
 238                         break;
 239                 case 1:         /* Class C */
 240                         (void)sprintf(qbuf, "0.%u.%u.%u.in-addr.arpa",
 241                                       netbr[3], netbr[2], netbr[1]);
 242                         break;
 243                 case 0:         /* Class D - E */
 244                         (void)sprintf(qbuf, "%u.%u.%u.%u.in-addr.arpa",
 245                                       netbr[3], netbr[2], netbr[1], netbr[0]);
 246                         break;
 247         }
 248         anslen = res_query(qbuf, C_IN, T_PTR, buf.buf, sizeof buf.buf);
 249         if (anslen < 0) {
 250 #ifdef DEBUG
 251                 if (_res.options & RES_DEBUG)
 252                         printf("res_query failed\n");
 253 #endif
 254                 if (errno == ECONNREFUSED)
 255                         return (_getnetbyaddr(net, net_type));
 256                 return (_getnetbyaddr(net, net_type));
 257         }
 258         net_entry = getnetanswer(&buf, anslen, BYADDR);
 259         if (net_entry) {
 260                 unsigned u_net = net;   /* maybe net should be unsigned ? */
 261
 262                 /* Strip trailing zeros */
 263                 while ((u_net & 0xff) == 0 && u_net != 0) {
 264                         u_net >>= 8;
 265                 }
 266                 net_entry->n_net = u_net;
 267                 return (net_entry);
 268         } else {
 269                 return (_getnetbyaddr(net, net_type));
 270         }
 271 }
 272
 273 struct netent *
 274 getnetbyname(net)
 275 #if defined(sun)
 276         register char *net;
 277 #else
 278         register const char *net;
 279 #endif
 280 {
 281         unsigned int    netbr[4];
 282         int             anslen;
 283         querybuf        buf;
 284         char            qbuf[MAXDNAME];
 285         struct netent   *net_entry;
 286
 287         (void)strcpy(&qbuf[0],net);
 288         anslen = res_search(qbuf, C_IN, T_PTR, buf.buf, sizeof buf.buf);
 289         if (anslen < 0) {
 290 #ifdef DEBUG
 291                 if (_res.options & RES_DEBUG)
 292                         printf("res_query failed\n");
 293 #endif
 294                 if (errno == ECONNREFUSED)
 295                         return (_getnetbyname(net));
 296                 return (_getnetbyname(net));
 297         }
 298         net_entry = getnetanswer(&buf, anslen, BYNAME);
 299         if (net_entry)
 300                 return (net_entry);
 301         else
 302                 return (_getnetbyname(net));
 303 }