StdLib/BsdSocketLib/gethostbydns.c

   1 /*
   2  * ++Copyright++ 1985, 1988, 1993
   3  * -
   4  * Copyright (c) 1985, 1988, 1993
   5  *      The Regents of the University of California.  All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  * 3. All advertising materials mentioning features or use of this software
  16  *    must display the following acknowledgement:
  17  *      This product includes software developed by the University of
  18  *      California, Berkeley and its contributors.
  19  * 4. Neither the name of the University nor the names of its contributors
  20  *    may be used to endorse or promote products derived from this software
  21  *    without specific prior written permission.
  22  *
  23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  33  * SUCH DAMAGE.
  34  * -
  35  * Portions Copyright (c) 1993 by Digital Equipment Corporation.
  36  *
  37  * Permission to use, copy, modify, and distribute this software for any
  38  * purpose with or without fee is hereby granted, provided that the above
  39  * copyright notice and this permission notice appear in all copies, and that
  40  * the name of Digital Equipment Corporation not be used in advertising or
  41  * publicity pertaining to distribution of the document or software without
  42  * specific, written prior permission.
  43  *
  44  * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
  45  * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
  46  * OF MERCHANTABILITY AND FITNESS.   IN NO EVENT SHALL DIGITAL EQUIPMENT
  47  * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
  48  * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
  49  * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
  50  * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
  51  * SOFTWARE.
  52  * -
  53  * --Copyright--
  54  */
  55
  56 /*
  57  * Portions copyright (c) 1999, 2000
  58  * Intel Corporation.
  59  * All rights reserved.
  60  *
  61  * Redistribution and use in source and binary forms, with or without
  62  * modification, are permitted provided that the following conditions
  63  * are met:
  64  *
  65  * 1. Redistributions of source code must retain the above copyright
  66  *    notice, this list of conditions and the following disclaimer.
  67  *
  68  * 2. Redistributions in binary form must reproduce the above copyright
  69  *    notice, this list of conditions and the following disclaimer in the
  70  *    documentation and/or other materials provided with the distribution.
  71  *
  72  * 3. All advertising materials mentioning features or use of this software
  73  *    must display the following acknowledgement:
  74  *
  75  *    This product includes software developed by Intel Corporation and
  76  *    its contributors.
  77  *
  78  * 4. Neither the name of Intel Corporation or its contributors may be
  79  *    used to endorse or promote products derived from this software
  80  *    without specific prior written permission.
  81  *
  82  * THIS SOFTWARE IS PROVIDED BY INTEL CORPORATION AND CONTRIBUTORS ``AS IS''
  83  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  84  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  85  * ARE DISCLAIMED.  IN NO EVENT SHALL INTEL CORPORATION OR CONTRIBUTORS BE
  86  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  87  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  88  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  89  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  90  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  91  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
  92  * THE POSSIBILITY OF SUCH DAMAGE.
  93  *
  94  */
  95
  96 #if defined(LIBC_SCCS) && !defined(lint)
  97 static char sccsid[] = "@(#)gethostnamadr.c     8.1 (Berkeley) 6/4/93";
  98 static char fromrcsid[] = "From: Id: gethnamaddr.c,v 8.23 1998/04/07 04:59:46 vixie Exp $";
  99 static char rcsid[] = "$Id: gethostbydns.c,v 1.1.1.1 2003/11/19 01:51:27 kyu3 Exp $";
 100 #endif /* LIBC_SCCS and not lint */
 101
 102 #include <sys/types.h>
 103 #include <sys/param.h>
 104 #include <sys/socket.h>
 105 #include <netinet/in.h>
 106 #include <arpa/inet.h>
 107 #include <arpa/nameser.h>
 108
 109 #include <stdio.h>
 110 #include <unistd.h>
 111 #include <string.h>
 112 #include <netdb.h>
 113 #include <resolv.h>
 114 #include <ctype.h>
 115 #include <errno.h>
 116 #ifdef _ORG_FREEBSD_
 117 #include <syslog.h>
 118 #else
 119 #include <stdlib.h>
 120 u_int32_t _getlong(const u_char *src);
 121 u_int16_t _getshort(const u_char *src);
 122 #endif
 123
 124 #include "res_config.h"
 125 #include "Socklib_internals.h"
 126
 127 #define SPRINTF(x) ((size_t)sprintf x)
 128
 129 #define MAXALIASES      35
 130 #define MAXADDRS        35
 131
 132 static const char AskedForGot[] =
 133                 "gethostby*.gethostanswer: asked for \"%s\", got \"%s\"";
 134
 135 static char *h_addr_ptrs[MAXADDRS + 1];
 136
 137 static struct hostent host;
 138 static char *host_aliases[MAXALIASES];
 139 static char hostbuf[8*1024];
 140 static u_char host_addr[16];    /* IPv4 or IPv6 */
 141
 142 #ifdef RESOLVSORT
 143 static void addrsort(char **, int);
 144 #endif
 145
 146 #if PACKETSZ > 1024
 147 #define MAXPACKET       PACKETSZ
 148 #else
 149 #define MAXPACKET       1024
 150 #endif
 151
 152 typedef union {
 153     HEADER hdr;
 154     u_char buf[MAXPACKET];
 155 } querybuf;
 156
 157 typedef union {
 158     int32_t al;
 159     char ac;
 160 } align;
 161
 162 extern int h_errno;
 163 int _dns_ttl_;
 164
 165 #ifdef DEBUG_RES
 166 static void
 167 dprintf(char *msg, int num)
 168 {
 169         if (_res.options & RES_DEBUG) {
 170                 int save = errno;
 171
 172                 printf(msg, num);
 173                 errno = save;
 174         }
 175 }
 176 #else
 177 # define dprintf(msg, num) /*nada*/
 178 #endif
 179
 180 #define BOUNDED_INCR(x) \
 181         do { \
 182                 cp += x; \
 183                 if (cp > eom) { \
 184                         h_errno = NO_RECOVERY; \
 185                         return (NULL); \
 186                 } \
 187         } while (0)
 188
 189 #define BOUNDS_CHECK(ptr, count) \
 190         do { \
 191                 if ((ptr) + (count) > eom) { \
 192                         h_errno = NO_RECOVERY; \
 193                         return (NULL); \
 194                 } \
 195         } while (0)
 196
 197 static struct hostent *
 198 gethostanswer(const querybuf *answer, int anslen, const char *qname, int qtype)
 199 {
 200         register const HEADER *hp;
 201         register const u_char *cp;
 202         register int n;
 203         const u_char *eom, *erdata;
 204         char *bp, **ap, **hap;
 205         int type, class, buflen, ancount, qdcount;
 206         int haveanswer, had_error;
 207         int toobig = 0;
 208         char tbuf[MAXDNAME];
 209         const char *tname;
 210         int (*name_ok)(const char *);
 211
 212         tname = qname;
 213         host.h_name = NULL;
 214         eom = answer->buf + anslen;
 215         switch (qtype) {
 216         case T_A:
 217         case T_AAAA:
 218                 name_ok = res_hnok;
 219                 break;
 220         case T_PTR:
 221                 name_ok = res_dnok;
 222                 break;
 223         default:
 224                 h_errno = NO_RECOVERY;
 225                 return (NULL);  /* XXX should be abort(); */
 226         }
 227         /*
 228          * find first satisfactory answer
 229          */
 230         hp = &answer->hdr;
 231         ancount = ntohs(hp->ancount);
 232         qdcount = ntohs(hp->qdcount);
 233         bp = hostbuf;
 234         buflen = sizeof hostbuf;
 235         cp = answer->buf;
 236         BOUNDED_INCR(HFIXEDSZ);
 237         if (qdcount != 1) {
 238                 h_errno = NO_RECOVERY;
 239                 return (NULL);
 240         }
 241         n = dn_expand(answer->buf, eom, cp, bp, buflen);
 242         if ((n < 0) || !(*name_ok)(bp)) {
 243                 h_errno = NO_RECOVERY;
 244                 return (NULL);
 245         }
 246         BOUNDED_INCR(n + QFIXEDSZ);
 247         if (qtype == T_A || qtype == T_AAAA) {
 248                 /* res_send() has already verified that the query name is the
 249                  * same as the one we sent; this just gets the expanded name
 250                  * (i.e., with the succeeding search-domain tacked on).
 251                  */
 252                 n = (int)strlen(bp) + 1;                /* for the \0 */
 253                 if (n >= MAXHOSTNAMELEN) {
 254                         h_errno = NO_RECOVERY;
 255                         return (NULL);
 256                 }
 257                 host.h_name = bp;
 258                 bp += n;
 259                 buflen -= n;
 260                 /* The qname can be abbreviated, but h_name is now absolute. */
 261                 qname = host.h_name;
 262         }
 263         ap = host_aliases;
 264         *ap = NULL;
 265         host.h_aliases = host_aliases;
 266         hap = h_addr_ptrs;
 267         *hap = NULL;
 268         host.h_addr_list = h_addr_ptrs;
 269         haveanswer = 0;
 270         had_error = 0;
 271         _dns_ttl_ = -1;
 272         while (ancount-- > 0 && cp < eom && !had_error) {
 273                 n = dn_expand(answer->buf, eom, cp, bp, buflen);
 274                 if ((n < 0) || !(*name_ok)(bp)) {
 275                         had_error++;
 276                         continue;
 277                 }
 278                 cp += n;                        /* name */
 279                 BOUNDS_CHECK(cp, 3 * INT16SZ + INT32SZ);
 280                 type = _getshort(cp);
 281                 cp += INT16SZ;                  /* type */
 282                 class = _getshort(cp);
 283                 cp += INT16SZ;                  /* class */
 284                 if (qtype == T_A  && type == T_A)
 285                         _dns_ttl_ = _getlong(cp);
 286                 cp += INT32SZ;                  /* TTL */
 287                 n = _getshort(cp);
 288                 cp += INT16SZ;                  /* len */
 289                 BOUNDS_CHECK(cp, n);
 290                 erdata = cp + n;
 291                 if (class != C_IN) {
 292                         /* XXX - debug? syslog? */
 293                         cp += n;
 294                         continue;               /* XXX - had_error++ ? */
 295                 }
 296                 if ((qtype == T_A || qtype == T_AAAA) && type == T_CNAME) {
 297                         if (ap >= &host_aliases[MAXALIASES-1])
 298                                 continue;
 299                         n = dn_expand(answer->buf, eom, cp, tbuf, sizeof tbuf);
 300                         if ((n < 0) || !(*name_ok)(tbuf)) {
 301                                 had_error++;
 302                                 continue;
 303                         }
 304                         cp += n;
 305                         if (cp != erdata) {
 306                                 h_errno = NO_RECOVERY;
 307                                 return (NULL);
 308                         }
 309                         /* Store alias. */
 310                         *ap++ = bp;
 311                         n = (int)strlen(bp) + 1;        /* for the \0 */
 312                         if (n >= MAXHOSTNAMELEN) {
 313                                 had_error++;
 314                                 continue;
 315                         }
 316                         bp += n;
 317                         buflen -= n;
 318                         /* Get canonical name. */
 319                         n = (int)strlen(tbuf) + 1;      /* for the \0 */
 320                         if (n > buflen || n >= MAXHOSTNAMELEN) {
 321                                 had_error++;
 322                                 continue;
 323                         }
 324                         strcpy(bp, tbuf);
 325                         host.h_name = bp;
 326                         bp += n;
 327                         buflen -= n;
 328                         continue;
 329                 }
 330                 if (qtype == T_PTR && type == T_CNAME) {
 331                         n = dn_expand(answer->buf, eom, cp, tbuf, sizeof tbuf);
 332                         if (n < 0 || !res_dnok(tbuf)) {
 333                                 had_error++;
 334                                 continue;
 335                         }
 336                         cp += n;
 337                         if (cp != erdata) {
 338                                 h_errno = NO_RECOVERY;
 339                                 return (NULL);
 340                         }
 341                         /* Get canonical name. */
 342                         n = (int)strlen(tbuf) + 1;      /* for the \0 */
 343                         if (n > buflen || n >= MAXHOSTNAMELEN) {
 344                                 had_error++;
 345                                 continue;
 346                         }
 347                         strcpy(bp, tbuf);
 348                         tname = bp;
 349                         bp += n;
 350                         buflen -= n;
 351                         continue;
 352                 }
 353                 if (type != qtype) {
 354 #ifdef _ORG_FREEBSD_
 355                         syslog(LOG_NOTICE|LOG_AUTH,
 356         "gethostby*.gethostanswer: asked for \"%s %s %s\", got type \"%s\"",
 357                                qname, p_class(C_IN), p_type(qtype),
 358                                p_type(type));
 359 #endif
 360                         cp += n;
 361                         continue;               /* XXX - had_error++ ? */
 362                 }
 363                 switch (type) {
 364                 case T_PTR:
 365                         if (strcasecmp(tname, bp) != 0) {
 366 #ifdef _ORG_FREEBSD_
 367                                 syslog(LOG_NOTICE|LOG_AUTH,
 368                                        AskedForGot, qname, bp);
 369 #endif
 370                                 cp += n;
 371                                 continue;       /* XXX - had_error++ ? */
 372                         }
 373                         n = dn_expand(answer->buf, eom, cp, bp, buflen);
 374                         if ((n < 0) || !res_hnok(bp)) {
 375                                 had_error++;
 376                                 break;
 377                         }
 378 #if MULTI_PTRS_ARE_ALIASES
 379                         cp += n;
 380                         if (cp != erdata) {
 381                                 h_errno = NO_RECOVERY;
 382                                 return (NULL);
 383                         }
 384                         if (!haveanswer)
 385                                 host.h_name = bp;
 386                         else if (ap < &host_aliases[MAXALIASES-1])
 387                                 *ap++ = bp;
 388                         else
 389                                 n = -1;
 390                         if (n != -1) {
 391                                 n = (int)strlen(bp) + 1;        /* for the \0 */
 392                                 if (n >= MAXHOSTNAMELEN) {
 393                                         had_error++;
 394                                         break;
 395                                 }
 396                                 bp += n;
 397                                 buflen -= n;
 398                         }
 399                         break;
 400 #else
 401                         host.h_name = bp;
 402                         if (_res.options & RES_USE_INET6) {
 403                                 n = strlen(bp) + 1;     /* for the \0 */
 404                                 if (n >= MAXHOSTNAMELEN) {
 405                                         had_error++;
 406                                         break;
 407                                 }
 408                                 bp += n;
 409                                 buflen -= n;
 410                                 _map_v4v6_hostent(&host, &bp, &buflen);
 411                         }
 412                         h_errno = NETDB_SUCCESS;
 413                         return (&host);
 414 #endif
 415                 case T_A:
 416                 case T_AAAA:
 417                         if (strcasecmp(host.h_name, bp) != 0) {
 418 #ifdef _ORG_FREEBSD_
 419                                 syslog(LOG_NOTICE|LOG_AUTH,
 420                                        AskedForGot, host.h_name, bp);
 421 #endif
 422                                 cp += n;
 423                                 continue;       /* XXX - had_error++ ? */
 424                         }
 425                         if (n != host.h_length) {
 426                                 cp += n;
 427                                 continue;
 428                         }
 429                         if (!haveanswer) {
 430                                 register int nn;
 431
 432                                 host.h_name = bp;
 433                                 nn = (int)strlen(bp) + 1;       /* for the \0 */
 434                                 bp += nn;
 435                                 buflen -= nn;
 436                         }
 437
 438                         bp += sizeof(align) - ((size_t)bp % sizeof(align));
 439
 440                         if (bp + n >= &hostbuf[sizeof hostbuf]) {
 441                                 dprintf("size (%d) too big\n", n);
 442                                 had_error++;
 443                                 continue;
 444                         }
 445                         if (hap >= &h_addr_ptrs[MAXADDRS-1]) {
 446                                 if (!toobig++)
 447                                         dprintf("Too many addresses (%d)\n",
 448                                                 MAXADDRS);
 449                                 cp += n;
 450                                 continue;
 451                         }
 452       *hap++ = bp;
 453                         bcopy(cp, bp, n);
 454                         bp += n;
 455                         buflen -= n;
 456                         cp += n;
 457                         if (cp != erdata) {
 458                                 h_errno = NO_RECOVERY;
 459                                 return (NULL);
 460                         }
 461                         break;
 462                 default:
 463                         dprintf("Impossible condition (type=%d)\n", type);
 464                         h_errno = NO_RECOVERY;
 465                         return (NULL);
 466                         /* BIND has abort() here, too risky on bad data */
 467                 }
 468                 if (!had_error)
 469                         haveanswer++;
 470         }
 471         if (haveanswer) {
 472                 *ap = NULL;
 473                 *hap = NULL;
 474 # if defined(RESOLVSORT)
 475                 /*
 476                  * Note: we sort even if host can take only one address
 477                  * in its return structures - should give it the "best"
 478                  * address in that case, not some random one
 479                  */
 480                 if (_res.nsort && haveanswer > 1 && qtype == T_A)
 481                         addrsort(h_addr_ptrs, haveanswer);
 482 # endif /*RESOLVSORT*/
 483                 if (!host.h_name) {
 484                         n = (int)strlen(qname) + 1;     /* for the \0 */
 485                         if (n > buflen || n >= MAXHOSTNAMELEN)
 486                                 goto no_recovery;
 487                         strcpy(bp, qname);
 488                         host.h_name = bp;
 489                         bp += n;
 490                         buflen -= n;
 491                 }
 492                 if (_res.options & RES_USE_INET6)
 493                         _map_v4v6_hostent(&host, &bp, &buflen);
 494                 h_errno = NETDB_SUCCESS;
 495                 return (&host);
 496         }
 497  no_recovery:
 498         h_errno = NO_RECOVERY;
 499         return (NULL);
 500 }
 501
 502 struct hostent *
 503 __dns_getanswer(const char *answer, int anslen, const char *qname, int qtype)
 504 {
 505         switch(qtype) {
 506         case T_AAAA:
 507                 host.h_addrtype = AF_INET6;
 508                 host.h_length = IN6ADDRSZ;
 509                 break;
 510         case T_A:
 511         default:
 512                 host.h_addrtype = AF_INET;
 513                 host.h_length = INADDRSZ;
 514                 break;
 515         }
 516
 517         return(gethostanswer((const querybuf *)answer, anslen, qname, qtype));
 518 }
 519
 520 struct hostent *
 521 _gethostbydnsname(const char *name, int af)
 522 {
 523         querybuf buf;
 524         register const char *cp;
 525         char *bp;
 526         int n, size, type, len;
 527
 528         if ((_res.options & RES_INIT) == 0 && res_init() == -1) {
 529                 h_errno = NETDB_INTERNAL;
 530                 return (NULL);
 531         }
 532
 533         switch (af) {
 534         case AF_INET:
 535                 size = INADDRSZ;
 536                 type = T_A;
 537                 break;
 538         case AF_INET6:
 539                 size = IN6ADDRSZ;
 540                 type = T_AAAA;
 541                 break;
 542         default:
 543                 h_errno = NETDB_INTERNAL;
 544                 errno = EAFNOSUPPORT;
 545                 return (NULL);
 546         }
 547
 548         host.h_addrtype = af;
 549         host.h_length = size;
 550
 551         /*
 552          * if there aren't any dots, it could be a user-level alias.
 553          * this is also done in res_query() since we are not the only
 554          * function that looks up host names.
 555          */
 556         if (!strchr(name, '.') && ( NULL != (cp = __hostalias(name))))
 557                 name = cp;
 558
 559         /*
 560          * disallow names consisting only of digits/dots, unless
 561          * they end in a dot.
 562          */
 563         if (isdigit(name[0]))
 564                 for (cp = name;; ++cp) {
 565                         if (!*cp) {
 566                                 if (*--cp == '.')
 567                                         break;
 568                                 /*
 569                                  * All-numeric, no dot at the end.
 570                                  * Fake up a hostent as if we'd actually
 571                                  * done a lookup.
 572                                  */
 573                                 if (inet_pton(af, name, host_addr) <= 0) {
 574                                         h_errno = HOST_NOT_FOUND;
 575                                         return (NULL);
 576                                 }
 577                                 strncpy(hostbuf, name, MAXDNAME);
 578                                 hostbuf[MAXDNAME] = '\0';
 579                                 bp = hostbuf + MAXDNAME;
 580                                 len = sizeof hostbuf - MAXDNAME;
 581                                 host.h_name = hostbuf;
 582                                 host.h_aliases = host_aliases;
 583                                 host_aliases[0] = NULL;
 584                                 h_addr_ptrs[0] = (char *)host_addr;
 585                                 h_addr_ptrs[1] = NULL;
 586                                 host.h_addr_list = h_addr_ptrs;
 587                                 if (_res.options & RES_USE_INET6)
 588                                         _map_v4v6_hostent(&host, &bp, &len);
 589                                 h_errno = NETDB_SUCCESS;
 590                                 return (&host);
 591                         }
 592                         if (!isdigit(*cp) && *cp != '.')
 593                                 break;
 594                 }
 595         if ((isxdigit(name[0]) && strchr(name, ':') != NULL) ||
 596             name[0] == ':')
 597                 for (cp = name;; ++cp) {
 598                         if (!*cp) {
 599                                 if (*--cp == '.')
 600                                         break;
 601                                 /*
 602                                  * All-IPv6-legal, no dot at the end.
 603                                  * Fake up a hostent as if we'd actually
 604                                  * done a lookup.
 605                                  */
 606                                 if (inet_pton(af, name, host_addr) <= 0) {
 607                                         h_errno = HOST_NOT_FOUND;
 608                                         return (NULL);
 609                                 }
 610                                 strncpy(hostbuf, name, MAXDNAME);
 611                                 hostbuf[MAXDNAME] = '\0';
 612                                 bp = hostbuf + MAXDNAME;
 613                                 len = sizeof hostbuf - MAXDNAME;
 614                                 host.h_name = hostbuf;
 615                                 host.h_aliases = host_aliases;
 616                                 host_aliases[0] = NULL;
 617                                 h_addr_ptrs[0] = (char *)host_addr;
 618                                 h_addr_ptrs[1] = NULL;
 619                                 host.h_addr_list = h_addr_ptrs;
 620                                 h_errno = NETDB_SUCCESS;
 621                                 return (&host);
 622                         }
 623                         if (!isxdigit(*cp) && *cp != ':' && *cp != '.')
 624                                 break;
 625                 }
 626
 627         if ((n = res_search(name, C_IN, type, buf.buf, sizeof(buf))) < 0) {
 628                 dprintf("res_search failed (%d)\n", n);
 629                 return (NULL);
 630         }
 631         return (gethostanswer(&buf, n, name, type));
 632 }
 633
 634 struct hostent *
 635 _gethostbydnsaddr(const char *addr, int len, int af)
 636 {
 637         const u_char *uaddr = (const u_char *)addr;
 638         static const u_char mapped[] = { 0,0, 0,0, 0,0, 0,0, 0,0, 0xff,0xff };
 639         static const u_char tunnelled[] = { 0,0, 0,0, 0,0, 0,0, 0,0, 0,0 };
 640         int n, size;
 641         querybuf buf;
 642         register struct hostent *hp;
 643         char qbuf[MAXDNAME+1], *qp;
 644 #ifdef SUNSECURITY
 645         register struct hostent *rhp;
 646         char **haddr;
 647         u_long old_options;
 648         char hname2[MAXDNAME+1];
 649 #endif /*SUNSECURITY*/
 650
 651         if ((_res.options & RES_INIT) == 0 && res_init() == -1) {
 652                 h_errno = NETDB_INTERNAL;
 653                 return (NULL);
 654         }
 655         if (af == AF_INET6 && len == IN6ADDRSZ &&
 656             (!bcmp(uaddr, mapped, sizeof mapped) ||
 657              !bcmp(uaddr, tunnelled, sizeof tunnelled))) {
 658                 /* Unmap. */
 659                 addr += sizeof mapped;
 660                 uaddr += sizeof mapped;
 661                 af = AF_INET;
 662                 len = INADDRSZ;
 663         }
 664         switch (af) {
 665         case AF_INET:
 666                 size = INADDRSZ;
 667                 break;
 668         case AF_INET6:
 669                 size = IN6ADDRSZ;
 670                 break;
 671         default:
 672                 errno = EAFNOSUPPORT;
 673                 h_errno = NETDB_INTERNAL;
 674                 return (NULL);
 675         }
 676         if (size != len) {
 677                 errno = EINVAL;
 678                 h_errno = NETDB_INTERNAL;
 679                 return (NULL);
 680         }
 681         switch (af) {
 682         case AF_INET:
 683                 (void) sprintf(qbuf, "%u.%u.%u.%u.in-addr.arpa",
 684                                (uaddr[3] & 0xff),
 685                                (uaddr[2] & 0xff),
 686                                (uaddr[1] & 0xff),
 687                                (uaddr[0] & 0xff));
 688                 break;
 689         case AF_INET6:
 690                 qp = qbuf;
 691                 for (n = IN6ADDRSZ - 1; n >= 0; n--) {
 692                         qp += SPRINTF((qp, "%x.%x.",
 693                                        uaddr[n] & 0xf,
 694                                        (uaddr[n] >> 4) & 0xf));
 695                 }
 696                 strcpy(qp, "ip6.int");
 697                 break;
 698         default:
 699                 abort();
 700         }
 701         n = res_query(qbuf, C_IN, T_PTR, (u_char *)buf.buf, sizeof buf.buf);
 702         if (n < 0) {
 703                 dprintf("res_query failed (%d)\n", n);
 704                 return (NULL);
 705         }
 706         if ( NULL == (hp = gethostanswer(&buf, n, qbuf, T_PTR)))
 707                 return (NULL);  /* h_errno was set by gethostanswer() */
 708 #ifdef SUNSECURITY
 709         if (af == AF_INET) {
 710             /*
 711              * turn off search as the name should be absolute,
 712              * 'localhost' should be matched by defnames
 713              */
 714             strncpy(hname2, hp->h_name, MAXDNAME);
 715             hname2[MAXDNAME] = '\0';
 716             old_options = _res.options;
 717             _res.options &= ~RES_DNSRCH;
 718             _res.options |= RES_DEFNAMES;
 719             if (!(rhp = gethostbyname(hname2))) {
 720 #ifdef _ORG_FREEBSD_
 721                 syslog(LOG_NOTICE|LOG_AUTH,
 722                        "gethostbyaddr: No A record for %s (verifying [%s])",
 723                        hname2, inet_ntoa(*((struct in_addr *)addr)));
 724 #endif
 725                 _res.options = old_options;
 726                 h_errno = HOST_NOT_FOUND;
 727                 return (NULL);
 728             }
 729             _res.options = old_options;
 730             for (haddr = rhp->h_addr_list; *haddr; haddr++)
 731                 if (!memcmp(*haddr, addr, INADDRSZ))
 732                         break;
 733             if (!*haddr) {
 734 #ifdef _ORG_FREEBSD_
 735                 syslog(LOG_NOTICE|LOG_AUTH,
 736                        "gethostbyaddr: A record of %s != PTR record [%s]",
 737                        hname2, inet_ntoa(*((struct in_addr *)addr)));
 738 #endif
 739                 h_errno = HOST_NOT_FOUND;
 740                 return (NULL);
 741             }
 742         }
 743 #endif /*SUNSECURITY*/
 744         hp->h_addrtype = af;
 745         hp->h_length = len;
 746         bcopy(addr, host_addr, len);
 747         h_addr_ptrs[0] = (char *)host_addr;
 748         h_addr_ptrs[1] = NULL;
 749         if (af == AF_INET && (_res.options & RES_USE_INET6)) {
 750                 _map_v4v6_address((char*)host_addr, (char*)host_addr);
 751                 hp->h_addrtype = AF_INET6;
 752                 hp->h_length = IN6ADDRSZ;
 753         }
 754         h_errno = NETDB_SUCCESS;
 755         return (hp);
 756 }
 757
 758 #ifdef RESOLVSORT
 759 static void
 760 addrsort(char **ap, int num)
 761 {
 762         short i, j;
 763         char **p;
 764         short aval[MAXADDRS];
 765         short needsort = 0;
 766
 767         p = ap;
 768         for (i = 0; i < num; i++, p++) {
 769             for (j = 0 ; (unsigned)j < _res.nsort; j++)
 770                 if (_res.sort_list[j].addr.s_addr ==
 771                     (((struct in_addr *)(*p))->s_addr & _res.sort_list[j].mask))
 772                         break;
 773             aval[i] = j;
 774             if (needsort == 0 && i > 0 && j < aval[i-1])
 775                 needsort = i;
 776         }
 777         if (!needsort)
 778             return;
 779
 780         while (needsort < num) {
 781             for (j = needsort - 1; j >= 0; j--) {
 782                 if (aval[j] > aval[j+1]) {
 783                     char *hp;
 784
 785                     i = aval[j];
 786                     aval[j] = aval[j+1];
 787                     aval[j+1] = i;
 788
 789                     hp = ap[j];
 790                     ap[j] = ap[j+1];
 791                     ap[j+1] = hp;
 792
 793                 } else
 794                     break;
 795             }
 796             needsort++;
 797         }
 798 }
 799 #endif
 800 void
 801 _sethostdnsent(int stayopen)
 802 {
 803         if ((_res.options & RES_INIT) == 0 && res_init() == -1)
 804                 return;
 805         if (stayopen)
 806                 _res.options |= RES_STAYOPEN | RES_USEVC;
 807 }
 808
 809 void
 810 _endhostdnsent()
 811 {
 812         _res.options &= ~(RES_STAYOPEN | RES_USEVC);
 813         res_close();
 814 }