resolv/gethnamaddr.c

   1 /*
   2  * Copyright (c) 1985, 1988 Regents of the University of California.
   3  * 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
  34 #if defined(LIBC_SCCS) && !defined(lint)
  35 static char sccsid[] = "@(#)gethostnamadr.c     6.45 (Berkeley) 2/24/91";
  36 #endif /* LIBC_SCCS and not lint */
  37
  38 #include <sys/param.h>
  39 #include <sys/socket.h>
  40 #include <netinet/in.h>
  41 #include <arpa/inet.h>
  42 #include <arpa/nameser.h>
  43 #include <netdb.h>
  44 #include <resolv.h>
  45 #include <stdio.h>
  46 #include <ctype.h>
  47 #include <errno.h>
  48 #include <string.h>
  49
  50 #define MAXALIASES      35
  51 #define MAXADDRS        35
  52
  53 static char *h_addr_ptrs[MAXADDRS + 1];
  54
  55 static struct hostent host;
  56 static char *host_aliases[MAXALIASES];
  57 static char hostbuf[BUFSIZ+1];
  58 static struct in_addr host_addr;
  59 static FILE *hostf = NULL;
  60 static char hostaddr[MAXADDRS];
  61 static char *host_addrs[2];
  62 static int stayopen = 0;
  63 char *strpbrk();
  64
  65 #if PACKETSZ > 1024
  66 #define MAXPACKET       PACKETSZ
  67 #else
  68 #define MAXPACKET       1024
  69 #endif
  70
  71 typedef union {
  72     HEADER hdr;
  73     u_char buf[MAXPACKET];
  74 } querybuf;
  75
  76 typedef union {
  77     long al;
  78     char ac;
  79 } align;
  80
  81 int h_errno;
  82
  83 static struct hostent *
  84 getanswer(answer, anslen, iquery)
  85         querybuf *answer;
  86         int anslen;
  87         int iquery;
  88 {
  89         register HEADER *hp;
  90         register u_char *cp;
  91         register int n;
  92         u_char *eom;
  93         char *bp, **ap;
  94         int type, class, buflen, ancount, qdcount;
  95         int haveanswer, getclass = C_ANY;
  96         char **hap;
  97
  98         eom = answer->buf + anslen;
  99         /*
 100          * find first satisfactory answer
 101          */
 102         hp = &answer->hdr;
 103         ancount = ntohs(hp->ancount);
 104         qdcount = ntohs(hp->qdcount);
 105         bp = hostbuf;
 106         buflen = sizeof(hostbuf);
 107         cp = answer->buf + sizeof(HEADER);
 108         if (qdcount) {
 109                 if (iquery) {
 110                         if ((n = dn_expand((u_char *)answer->buf,
 111                             (u_char *)eom, (u_char *)cp, (u_char *)bp,
 112                             buflen)) < 0) {
 113                                 h_errno = NO_RECOVERY;
 114                                 return ((struct hostent *) NULL);
 115                         }
 116                         cp += n + QFIXEDSZ;
 117                         host.h_name = bp;
 118                         n = strlen(bp) + 1;
 119                         bp += n;
 120                         buflen -= n;
 121                 } else
 122                         cp += __dn_skipname(cp, eom) + QFIXEDSZ;
 123                 while (--qdcount > 0)
 124                         cp += __dn_skipname(cp, eom) + QFIXEDSZ;
 125         } else if (iquery) {
 126                 if (hp->aa)
 127                         h_errno = HOST_NOT_FOUND;
 128                 else
 129                         h_errno = TRY_AGAIN;
 130                 return ((struct hostent *) NULL);
 131         }
 132         ap = host_aliases;
 133         *ap = NULL;
 134         host.h_aliases = host_aliases;
 135         hap = h_addr_ptrs;
 136         *hap = NULL;
 137 #if BSD >= 43 || defined(h_addr)        /* new-style hostent structure */
 138         host.h_addr_list = h_addr_ptrs;
 139 #endif
 140         haveanswer = 0;
 141         while (--ancount >= 0 && cp < eom) {
 142                 if ((n = dn_expand((u_char *)answer->buf, (u_char *)eom,
 143                     (u_char *)cp, (u_char *)bp, buflen)) < 0)
 144                         break;
 145                 cp += n;
 146                 type = _getshort(cp);
 147                 cp += sizeof(u_short);
 148                 class = _getshort(cp);
 149                 cp += sizeof(u_short) + sizeof(u_long);
 150                 n = _getshort(cp);
 151                 cp += sizeof(u_short);
 152                 if (type == T_CNAME) {
 153                         cp += n;
 154                         if (ap >= &host_aliases[MAXALIASES-1])
 155                                 continue;
 156                         *ap++ = bp;
 157                         n = strlen(bp) + 1;
 158                         bp += n;
 159                         buflen -= n;
 160                         continue;
 161                 }
 162                 if (iquery && type == T_PTR) {
 163                         if ((n = dn_expand((u_char *)answer->buf,
 164                             (u_char *)eom, (u_char *)cp, (u_char *)bp,
 165                             buflen)) < 0) {
 166                                 cp += n;
 167                                 continue;
 168                         }
 169                         cp += n;
 170                         host.h_name = bp;
 171                         return(&host);
 172                 }
 173                 if (iquery || type != T_A)  {
 174 #ifdef DEBUG
 175                         if (_res.options & RES_DEBUG)
 176                                 printf("unexpected answer type %d, size %d\n",
 177                                         type, n);
 178 #endif
 179                         cp += n;
 180                         continue;
 181                 }
 182                 if (haveanswer) {
 183                         if (n != host.h_length) {
 184                                 cp += n;
 185                                 continue;
 186                         }
 187                         if (class != getclass) {
 188                                 cp += n;
 189                                 continue;
 190                         }
 191                 } else {
 192                         host.h_length = n;
 193                         getclass = class;
 194                         host.h_addrtype = (class == C_IN) ? AF_INET : AF_UNSPEC;
 195                         if (!iquery) {
 196                                 host.h_name = bp;
 197                                 bp += strlen(bp) + 1;
 198                         }
 199                 }
 200
 201                 bp += sizeof(align) - ((u_long)bp % sizeof(align));
 202
 203                 if (bp + n >= &hostbuf[sizeof(hostbuf)]) {
 204 #ifdef DEBUG
 205                         if (_res.options & RES_DEBUG)
 206                                 printf("size (%d) too big\n", n);
 207 #endif
 208                         break;
 209                 }
 210                 bcopy(cp, *hap++ = bp, n);
 211                 bp +=n;
 212                 cp += n;
 213                 haveanswer++;
 214         }
 215         if (haveanswer) {
 216                 *ap = NULL;
 217 #if BSD >= 43 || defined(h_addr)        /* new-style hostent structure */
 218                 *hap = NULL;
 219 #else
 220                 host.h_addr = h_addr_ptrs[0];
 221 #endif
 222                 return (&host);
 223         } else {
 224                 h_errno = TRY_AGAIN;
 225                 return ((struct hostent *) NULL);
 226         }
 227 }
 228
 229 struct hostent *
 230 gethostbyname(name)
 231         char *name;
 232 {
 233         querybuf buf;
 234         register char *cp;
 235         int n;
 236         extern struct hostent *_gethtbyname();
 237
 238         /*
 239          * disallow names consisting only of digits/dots, unless
 240          * they end in a dot.
 241          */
 242         if (isdigit(name[0]))
 243                 for (cp = name;; ++cp) {
 244                         if (!*cp) {
 245                                 if (*--cp == '.')
 246                                         break;
 247                                 /*
 248                                  * All-numeric, no dot at the end.
 249                                  * Fake up a hostent as if we'd actually
 250                                  * done a lookup.  What if someone types
 251                                  * 255.255.255.255?  The test below will
 252                                  * succeed spuriously... ???
 253                                  */
 254                                 if ((host_addr.s_addr = inet_addr(name)) == -1) {
 255                                         h_errno = HOST_NOT_FOUND;
 256                                         return((struct hostent *) NULL);
 257                                 }
 258                                 host.h_name = name;
 259                                 host.h_aliases = host_aliases;
 260                                 host_aliases[0] = NULL;
 261                                 host.h_addrtype = AF_INET;
 262                                 host.h_length = sizeof(u_long);
 263                                 h_addr_ptrs[0] = (char *)&host_addr;
 264                                 h_addr_ptrs[1] = (char *)0;
 265 #if BSD >= 43 || defined(h_addr)        /* new-style hostent structure */
 266                                 host.h_addr_list = h_addr_ptrs;
 267 #else
 268                                 host.h_addr = h_addr_ptrs[0];
 269 #endif
 270                                 return (&host);
 271                         }
 272                         if (!isdigit(*cp) && *cp != '.')
 273                                 break;
 274                 }
 275
 276         if ((n = res_search(name, C_IN, T_A, buf.buf, sizeof(buf))) < 0) {
 277 #ifdef DEBUG
 278                 if (_res.options & RES_DEBUG)
 279                         printf("res_search failed\n");
 280 #endif
 281                 if (errno == ECONNREFUSED)
 282                         return (_gethtbyname(name));
 283                 else
 284                         return ((struct hostent *) NULL);
 285         }
 286         return (getanswer(&buf, n, 0));
 287 }
 288
 289 struct hostent *
 290 gethostbyaddr(addr, len, type)
 291         const char *addr;
 292         int len, type;
 293 {
 294         int n;
 295         querybuf buf;
 296         register struct hostent *hp;
 297         char qbuf[MAXDNAME];
 298         extern struct hostent *_gethtbyaddr();
 299
 300         if (type != AF_INET)
 301                 return ((struct hostent *) NULL);
 302         (void)sprintf(qbuf, "%u.%u.%u.%u.in-addr.arpa",
 303                 ((unsigned)addr[3] & 0xff),
 304                 ((unsigned)addr[2] & 0xff),
 305                 ((unsigned)addr[1] & 0xff),
 306                 ((unsigned)addr[0] & 0xff));
 307         n = res_query(qbuf, C_IN, T_PTR, (char *)&buf, sizeof(buf));
 308         if (n < 0) {
 309 #ifdef DEBUG
 310                 if (_res.options & RES_DEBUG)
 311                         printf("res_query failed\n");
 312 #endif
 313                 if (errno == ECONNREFUSED)
 314                         return (_gethtbyaddr(addr, len, type));
 315                 return ((struct hostent *) NULL);
 316         }
 317         hp = getanswer(&buf, n, 1);
 318         if (hp == NULL)
 319                 return ((struct hostent *) NULL);
 320         hp->h_addrtype = type;
 321         hp->h_length = len;
 322         h_addr_ptrs[0] = (char *)&host_addr;
 323         h_addr_ptrs[1] = (char *)0;
 324         host_addr = *(struct in_addr *)addr;
 325 #if BSD < 43 && !defined(h_addr)        /* new-style hostent structure */
 326         hp->h_addr = h_addr_ptrs[0];
 327 #endif
 328         return(hp);
 329 }
 330
 331 _sethtent(f)
 332         int f;
 333 {
 334         if (hostf == NULL)
 335                 hostf = fopen(_PATH_HOSTS, "r" );
 336         else
 337                 rewind(hostf);
 338         stayopen |= f;
 339 }
 340
 341 _endhtent()
 342 {
 343         if (hostf && !stayopen) {
 344                 (void) fclose(hostf);
 345                 hostf = NULL;
 346         }
 347 }
 348
 349 struct hostent *
 350 _gethtent()
 351 {
 352         char *p;
 353         register char *cp, **q;
 354
 355         if (hostf == NULL && (hostf = fopen(_PATH_HOSTS, "r" )) == NULL)
 356                 return (NULL);
 357 again:
 358         if ((p = fgets(hostbuf, BUFSIZ, hostf)) == NULL)
 359                 return (NULL);
 360         if (*p == '#')
 361                 goto again;
 362         cp = strpbrk(p, "#\n");
 363         if (cp == NULL)
 364                 goto again;
 365         *cp = '\0';
 366         cp = strpbrk(p, " \t");
 367         if (cp == NULL)
 368                 goto again;
 369         *cp++ = '\0';
 370         /* THIS STUFF IS INTERNET SPECIFIC */
 371 #if BSD >= 43 || defined(h_addr)        /* new-style hostent structure */
 372         host.h_addr_list = host_addrs;
 373 #endif
 374         host.h_addr = hostaddr;
 375         *((u_long *)host.h_addr) = inet_addr(p);
 376         host.h_length = sizeof (u_long);
 377         host.h_addrtype = AF_INET;
 378         while (*cp == ' ' || *cp == '\t')
 379                 cp++;
 380         host.h_name = cp;
 381         q = host.h_aliases = host_aliases;
 382         cp = strpbrk(cp, " \t");
 383         if (cp != NULL)
 384                 *cp++ = '\0';
 385         while (cp && *cp) {
 386                 if (*cp == ' ' || *cp == '\t') {
 387                         cp++;
 388                         continue;
 389                 }
 390                 if (q < &host_aliases[MAXALIASES - 1])
 391                         *q++ = cp;
 392                 cp = strpbrk(cp, " \t");
 393                 if (cp != NULL)
 394                         *cp++ = '\0';
 395         }
 396         *q = NULL;
 397         return (&host);
 398 }
 399
 400 struct hostent *
 401 _gethtbyname(name)
 402         char *name;
 403 {
 404         register struct hostent *p;
 405         register char **cp;
 406
 407         _sethtent(0);
 408         while (p = _gethtent()) {
 409                 if (strcasecmp(p->h_name, name) == 0)
 410                         break;
 411                 for (cp = p->h_aliases; *cp != 0; cp++)
 412                         if (strcasecmp(*cp, name) == 0)
 413                                 goto found;
 414         }
 415 found:
 416         _endhtent();
 417         return (p);
 418 }
 419
 420 struct hostent *
 421 _gethtbyaddr(addr, len, type)
 422         const char *addr;
 423         int len, type;
 424 {
 425         register struct hostent *p;
 426
 427         _sethtent(0);
 428         while (p = _gethtent())
 429                 if (p->h_addrtype == type && !bcmp(p->h_addr, addr, len))
 430                         break;
 431         _endhtent();
 432         return (p);
 433 }