lib/libc/net/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  * @(#)gethostnamadr.c  8.1 (Berkeley) 6/4/93
  56  * $From: Id: gethnamaddr.c,v 8.23 1998/04/07 04:59:46 vixie Exp $
  57  * $FreeBSD: src/lib/libc/net/gethostbydns.c,v 1.27.2.5 2002/11/02 18:54:57 ume Exp $
  58  * $DragonFly: src/lib/libc/net/gethostbydns.c,v 1.4 2004/10/25 19:38:01 drhodus Exp $
  59  */
  60
  61 #include <sys/types.h>
  62 #include <sys/param.h>
  63 #include <sys/socket.h>
  64 #include <netinet/in.h>
  65 #include <arpa/inet.h>
  66 #include <arpa/nameser.h>
  67
  68 #include <stdio.h>
  69 #include <stdlib.h>
  70 #include <unistd.h>
  71 #include <string.h>
  72 #include <netdb.h>
  73 #include <resolv.h>
  74 #include <ctype.h>
  75 #include <errno.h>
  76 #include <syslog.h>
  77
  78 #include "res_config.h"
  79
  80 #define SPRINTF(x) ((size_t)sprintf x)
  81
  82 #define MAXALIASES      35
  83 #define MAXADDRS        35
  84
  85 static const char AskedForGot[] =
  86                 "gethostby*.gethostanswer: asked for \"%s\", got \"%s\"";
  87
  88 static char *h_addr_ptrs[MAXADDRS + 1];
  89
  90 static struct hostent host;
  91 static char *host_aliases[MAXALIASES];
  92 static char hostbuf[8*1024];
  93 static u_char host_addr[16];    /* IPv4 or IPv6 */
  94
  95 #ifdef RESOLVSORT
  96 static void addrsort (char **, int);
  97 #endif
  98
  99 #define MAXPACKET       (64*1024)
 100
 101 typedef union {
 102     HEADER hdr;
 103     u_char buf[MAXPACKET];
 104 } querybuf;
 105
 106 typedef union {
 107     int32_t al;
 108     char ac;
 109 } align;
 110
 111 extern int h_errno;
 112 int _dns_ttl_;
 113
 114 #ifdef DEBUG
 115 static void
 116 dprintf(msg, num)
 117         char *msg;
 118         int num;
 119 {
 120         if (_res.options & RES_DEBUG) {
 121                 int save = errno;
 122
 123                 printf(msg, num);
 124                 errno = save;
 125         }
 126 }
 127 #else
 128 # define dprintf(msg, num) /*nada*/
 129 #endif
 130
 131 #define BOUNDED_INCR(x) \
 132         do { \
 133                 cp += x; \
 134                 if (cp > eom) { \
 135                         h_errno = NO_RECOVERY; \
 136                         return (NULL); \
 137                 } \
 138         } while (0)
 139
 140 #define BOUNDS_CHECK(ptr, count) \
 141         do { \
 142                 if ((ptr) + (count) > eom) { \
 143                         h_errno = NO_RECOVERY; \
 144                         return (NULL); \
 145                 } \
 146         } while (0)
 147
 148 static struct hostent *
 149 gethostanswer(answer, anslen, qname, qtype)
 150         const querybuf *answer;
 151         int anslen;
 152         const char *qname;
 153         int qtype;
 154 {
 155         const HEADER *hp;
 156         const u_char *cp;
 157         int n;
 158         const u_char *eom, *erdata;
 159         char *bp, **ap, **hap;
 160         int type, class, buflen, ancount, qdcount;
 161         int haveanswer, had_error;
 162         int toobig = 0;
 163         char tbuf[MAXDNAME];
 164         const char *tname;
 165         int (*name_ok) (const char *);
 166
 167         tname = qname;
 168         host.h_name = NULL;
 169         eom = answer->buf + anslen;
 170         switch (qtype) {
 171         case T_A:
 172         case T_AAAA:
 173                 name_ok = res_hnok;
 174                 break;
 175         case T_PTR:
 176                 name_ok = res_dnok;
 177                 break;
 178         default:
 179                 h_errno = NO_RECOVERY;
 180                 return (NULL);  /* XXX should be abort(); */
 181         }
 182         /*
 183          * find first satisfactory answer
 184          */
 185         hp = &answer->hdr;
 186         ancount = ntohs(hp->ancount);
 187         qdcount = ntohs(hp->qdcount);
 188         bp = hostbuf;
 189         buflen = sizeof hostbuf;
 190         cp = answer->buf;
 191         BOUNDED_INCR(HFIXEDSZ);
 192         if (qdcount != 1) {
 193                 h_errno = NO_RECOVERY;
 194                 return (NULL);
 195         }
 196         n = dn_expand(answer->buf, eom, cp, bp, buflen);
 197         if ((n < 0) || !(*name_ok)(bp)) {
 198                 h_errno = NO_RECOVERY;
 199                 return (NULL);
 200         }
 201         BOUNDED_INCR(n + QFIXEDSZ);
 202         if (qtype == T_A || qtype == T_AAAA) {
 203                 /* res_send() has already verified that the query name is the
 204                  * same as the one we sent; this just gets the expanded name
 205                  * (i.e., with the succeeding search-domain tacked on).
 206                  */
 207                 n = strlen(bp) + 1;             /* for the \0 */
 208                 if (n >= MAXHOSTNAMELEN) {
 209                         h_errno = NO_RECOVERY;
 210                         return (NULL);
 211                 }
 212                 host.h_name = bp;
 213                 bp += n;
 214                 buflen -= n;
 215                 /* The qname can be abbreviated, but h_name is now absolute. */
 216                 qname = host.h_name;
 217         }
 218         ap = host_aliases;
 219         *ap = NULL;
 220         host.h_aliases = host_aliases;
 221         hap = h_addr_ptrs;
 222         *hap = NULL;
 223         host.h_addr_list = h_addr_ptrs;
 224         haveanswer = 0;
 225         had_error = 0;
 226         _dns_ttl_ = -1;
 227         while (ancount-- > 0 && cp < eom && !had_error) {
 228                 n = dn_expand(answer->buf, eom, cp, bp, buflen);
 229                 if ((n < 0) || !(*name_ok)(bp)) {
 230                         had_error++;
 231                         continue;
 232                 }
 233                 cp += n;                        /* name */
 234                 BOUNDS_CHECK(cp, 3 * INT16SZ + INT32SZ);
 235                 type = _getshort(cp);
 236                 cp += INT16SZ;                  /* type */
 237                 class = _getshort(cp);
 238                 cp += INT16SZ;                  /* class */
 239                 if (qtype == T_A  && type == T_A)
 240                         _dns_ttl_ = _getlong(cp);
 241                 cp += INT32SZ;                  /* TTL */
 242                 n = _getshort(cp);
 243                 cp += INT16SZ;                  /* len */
 244                 BOUNDS_CHECK(cp, n);
 245                 erdata = cp + n;
 246                 if (class != C_IN) {
 247                         /* XXX - debug? syslog? */
 248                         cp += n;
 249                         continue;               /* XXX - had_error++ ? */
 250                 }
 251                 if ((qtype == T_A || qtype == T_AAAA) && type == T_CNAME) {
 252                         if (ap >= &host_aliases[MAXALIASES-1])
 253                                 continue;
 254                         n = dn_expand(answer->buf, eom, cp, tbuf, sizeof tbuf);
 255                         if ((n < 0) || !(*name_ok)(tbuf)) {
 256                                 had_error++;
 257                                 continue;
 258                         }
 259                         cp += n;
 260                         if (cp != erdata) {
 261                                 h_errno = NO_RECOVERY;
 262                                 return (NULL);
 263                         }
 264                         /* Store alias. */
 265                         *ap++ = bp;
 266                         n = strlen(bp) + 1;     /* for the \0 */
 267                         if (n >= MAXHOSTNAMELEN) {
 268                                 had_error++;
 269                                 continue;
 270                         }
 271                         bp += n;
 272                         buflen -= n;
 273                         /* Get canonical name. */
 274                         n = strlen(tbuf) + 1;   /* for the \0 */
 275                         if (n > buflen || n >= MAXHOSTNAMELEN) {
 276                                 had_error++;
 277                                 continue;
 278                         }
 279                         strcpy(bp, tbuf);
 280                         host.h_name = bp;
 281                         bp += n;
 282                         buflen -= n;
 283                         continue;
 284                 }
 285                 if (qtype == T_PTR && type == T_CNAME) {
 286                         n = dn_expand(answer->buf, eom, cp, tbuf, sizeof tbuf);
 287                         if (n < 0 || !res_dnok(tbuf)) {
 288                                 had_error++;
 289                                 continue;
 290                         }
 291                         cp += n;
 292                         if (cp != erdata) {
 293                                 h_errno = NO_RECOVERY;
 294                                 return (NULL);
 295                         }
 296                         /* Get canonical name. */
 297                         n = strlen(tbuf) + 1;   /* for the \0 */
 298                         if (n > buflen || n >= MAXHOSTNAMELEN) {
 299                                 had_error++;
 300                                 continue;
 301                         }
 302                         strcpy(bp, tbuf);
 303                         tname = bp;
 304                         bp += n;
 305                         buflen -= n;
 306                         continue;
 307                 }
 308                 if (type != qtype) {
 309                         if (type != T_SIG)
 310                                 syslog(LOG_NOTICE|LOG_AUTH,
 311         "gethostby*.gethostanswer: asked for \"%s %s %s\", got type \"%s\"",
 312                                        qname, p_class(C_IN), p_type(qtype),
 313                                        p_type(type));
 314                         cp += n;
 315                         continue;               /* XXX - had_error++ ? */
 316                 }
 317                 switch (type) {
 318                 case T_PTR:
 319                         if (strcasecmp(tname, bp) != 0) {
 320                                 syslog(LOG_NOTICE|LOG_AUTH,
 321                                        AskedForGot, qname, bp);
 322                                 cp += n;
 323                                 continue;       /* XXX - had_error++ ? */
 324                         }
 325                         n = dn_expand(answer->buf, eom, cp, bp, buflen);
 326                         if ((n < 0) || !res_hnok(bp)) {
 327                                 had_error++;
 328                                 break;
 329                         }
 330 #if MULTI_PTRS_ARE_ALIASES
 331                         cp += n;
 332                         if (cp != erdata) {
 333                                 h_errno = NO_RECOVERY;
 334                                 return (NULL);
 335                         }
 336                         if (!haveanswer)
 337                                 host.h_name = bp;
 338                         else if (ap < &host_aliases[MAXALIASES-1])
 339                                 *ap++ = bp;
 340                         else
 341                                 n = -1;
 342                         if (n != -1) {
 343                                 n = strlen(bp) + 1;     /* for the \0 */
 344                                 if (n >= MAXHOSTNAMELEN) {
 345                                         had_error++;
 346                                         break;
 347                                 }
 348                                 bp += n;
 349                                 buflen -= n;
 350                         }
 351                         break;
 352 #else
 353                         host.h_name = bp;
 354                         if (_res.options & RES_USE_INET6) {
 355                                 n = strlen(bp) + 1;     /* for the \0 */
 356                                 if (n >= MAXHOSTNAMELEN) {
 357                                         had_error++;
 358                                         break;
 359                                 }
 360                                 bp += n;
 361                                 buflen -= n;
 362                                 _map_v4v6_hostent(&host, &bp, &buflen);
 363                         }
 364                         h_errno = NETDB_SUCCESS;
 365                         return (&host);
 366 #endif
 367                 case T_A:
 368                 case T_AAAA:
 369                         if (strcasecmp(host.h_name, bp) != 0) {
 370                                 syslog(LOG_NOTICE|LOG_AUTH,
 371                                        AskedForGot, host.h_name, bp);
 372                                 cp += n;
 373                                 continue;       /* XXX - had_error++ ? */
 374                         }
 375                         if (n != host.h_length) {
 376                                 cp += n;
 377                                 continue;
 378                         }
 379                         if (!haveanswer) {
 380                                 int nn;
 381
 382                                 host.h_name = bp;
 383                                 nn = strlen(bp) + 1;    /* for the \0 */
 384                                 bp += nn;
 385                                 buflen -= nn;
 386                         }
 387
 388                         buflen -= sizeof(align) - ((u_long)bp % sizeof(align));
 389                         bp += sizeof(align) - ((u_long)bp % sizeof(align));
 390
 391                         if (bp + n >= &hostbuf[sizeof hostbuf]) {
 392                                 dprintf("size (%d) too big\n", n);
 393                                 had_error++;
 394                                 continue;
 395                         }
 396                         if (hap >= &h_addr_ptrs[MAXADDRS-1]) {
 397                                 if (!toobig++)
 398                                         dprintf("Too many addresses (%d)\n",
 399                                                 MAXADDRS);
 400                                 cp += n;
 401                                 continue;
 402                         }
 403                         bcopy(cp, *hap++ = bp, n);
 404                         bp += n;
 405                         buflen -= n;
 406                         cp += n;
 407                         if (cp != erdata) {
 408                                 h_errno = NO_RECOVERY;
 409                                 return (NULL);
 410                         }
 411                         break;
 412                 default:
 413                         dprintf("Impossible condition (type=%d)\n", type);
 414                         h_errno = NO_RECOVERY;
 415                         return (NULL);
 416                         /* BIND has abort() here, too risky on bad data */
 417                 }
 418                 if (!had_error)
 419                         haveanswer++;
 420         }
 421         if (haveanswer) {
 422                 *ap = NULL;
 423                 *hap = NULL;
 424 # if defined(RESOLVSORT)
 425                 /*
 426                  * Note: we sort even if host can take only one address
 427                  * in its return structures - should give it the "best"
 428                  * address in that case, not some random one
 429                  */
 430                 if (_res.nsort && haveanswer > 1 && qtype == T_A)
 431                         addrsort(h_addr_ptrs, haveanswer);
 432 # endif /*RESOLVSORT*/
 433                 if (!host.h_name) {
 434                         n = strlen(qname) + 1;  /* for the \0 */
 435                         if (n > buflen || n >= MAXHOSTNAMELEN)
 436                                 goto no_recovery;
 437                         strcpy(bp, qname);
 438                         host.h_name = bp;
 439                         bp += n;
 440                         buflen -= n;
 441                 }
 442                 if (_res.options & RES_USE_INET6)
 443                         _map_v4v6_hostent(&host, &bp, &buflen);
 444                 h_errno = NETDB_SUCCESS;
 445                 return (&host);
 446         }
 447  no_recovery:
 448         h_errno = NO_RECOVERY;
 449         return (NULL);
 450 }
 451
 452 struct hostent *
 453 __dns_getanswer(answer, anslen, qname, qtype)
 454         const char *answer;
 455         int anslen;
 456         const char *qname;
 457         int qtype;
 458 {
 459         switch(qtype) {
 460         case T_AAAA:
 461                 host.h_addrtype = AF_INET6;
 462                 host.h_length = IN6ADDRSZ;
 463                 break;
 464         case T_A:
 465         default:
 466                 host.h_addrtype = AF_INET;
 467                 host.h_length = INADDRSZ;
 468                 break;
 469         }
 470
 471         return(gethostanswer((const querybuf *)answer, anslen, qname, qtype));
 472 }
 473
 474 struct hostent *
 475 _gethostbydnsname(name, af)
 476         const char *name;
 477         int af;
 478 {
 479         querybuf *buf;
 480         const char *cp;
 481         char *bp;
 482         int n, size, type, len;
 483         struct hostent *hp;
 484
 485         if ((_res.options & RES_INIT) == 0 && res_init() == -1) {
 486                 h_errno = NETDB_INTERNAL;
 487                 return (NULL);
 488         }
 489
 490         switch (af) {
 491         case AF_INET:
 492                 size = INADDRSZ;
 493                 type = T_A;
 494                 break;
 495         case AF_INET6:
 496                 size = IN6ADDRSZ;
 497                 type = T_AAAA;
 498                 break;
 499         default:
 500                 h_errno = NETDB_INTERNAL;
 501                 errno = EAFNOSUPPORT;
 502                 return (NULL);
 503         }
 504
 505         host.h_addrtype = af;
 506         host.h_length = size;
 507
 508         /*
 509          * if there aren't any dots, it could be a user-level alias.
 510          * this is also done in res_query() since we are not the only
 511          * function that looks up host names.
 512          */
 513         if (!strchr(name, '.') && (cp = __hostalias(name)))
 514                 name = cp;
 515
 516         /*
 517          * disallow names consisting only of digits/dots, unless
 518          * they end in a dot.
 519          */
 520         if (isdigit((unsigned char)name[0]))
 521                 for (cp = name;; ++cp) {
 522                         if (!*cp) {
 523                                 if (*--cp == '.')
 524                                         break;
 525                                 /*
 526                                  * All-numeric, no dot at the end.
 527                                  * Fake up a hostent as if we'd actually
 528                                  * done a lookup.
 529                                  */
 530                                 if (inet_pton(af, name, host_addr) <= 0) {
 531                                         h_errno = HOST_NOT_FOUND;
 532                                         return (NULL);
 533                                 }
 534                                 strncpy(hostbuf, name, MAXDNAME);
 535                                 hostbuf[MAXDNAME] = '\0';
 536                                 bp = hostbuf + MAXDNAME;
 537                                 len = sizeof hostbuf - MAXDNAME;
 538                                 host.h_name = hostbuf;
 539                                 host.h_aliases = host_aliases;
 540                                 host_aliases[0] = NULL;
 541                                 h_addr_ptrs[0] = (char *)host_addr;
 542                                 h_addr_ptrs[1] = NULL;
 543                                 host.h_addr_list = h_addr_ptrs;
 544                                 if (_res.options & RES_USE_INET6)
 545                                         _map_v4v6_hostent(&host, &bp, &len);
 546                                 h_errno = NETDB_SUCCESS;
 547                                 return (&host);
 548                         }
 549                         if (!isdigit((unsigned char)*cp) && *cp != '.')
 550                                 break;
 551                 }
 552         if ((isxdigit((unsigned char)name[0]) && strchr(name, ':') != NULL) ||
 553             name[0] == ':')
 554                 for (cp = name;; ++cp) {
 555                         if (!*cp) {
 556                                 if (*--cp == '.')
 557                                         break;
 558                                 /*
 559                                  * All-IPv6-legal, no dot at the end.
 560                                  * Fake up a hostent as if we'd actually
 561                                  * done a lookup.
 562                                  */
 563                                 if (inet_pton(af, name, host_addr) <= 0) {
 564                                         h_errno = HOST_NOT_FOUND;
 565                                         return (NULL);
 566                                 }
 567                                 strncpy(hostbuf, name, MAXDNAME);
 568                                 hostbuf[MAXDNAME] = '\0';
 569                                 bp = hostbuf + MAXDNAME;
 570                                 len = sizeof hostbuf - MAXDNAME;
 571                                 host.h_name = hostbuf;
 572                                 host.h_aliases = host_aliases;
 573                                 host_aliases[0] = NULL;
 574                                 h_addr_ptrs[0] = (char *)host_addr;
 575                                 h_addr_ptrs[1] = NULL;
 576                                 host.h_addr_list = h_addr_ptrs;
 577                                 h_errno = NETDB_SUCCESS;
 578                                 return (&host);
 579                         }
 580                         if (!isxdigit((unsigned char)*cp) && *cp != ':' && *cp != '.')
 581                                 break;
 582                 }
 583
 584         if ((buf = malloc(sizeof(*buf))) == NULL) {
 585                 h_errno = NETDB_INTERNAL;
 586                 return (NULL);
 587         }
 588         n = res_search(name, C_IN, type, buf->buf, sizeof(buf->buf));
 589         if (n < 0) {
 590                 free(buf);
 591                 dprintf("res_search failed (%d)\n", n);
 592                 return (NULL);
 593         } else if (n > sizeof(buf->buf)) {
 594                 free(buf);
 595                 dprintf("static buffer is too small (%d)\n", n);
 596                 return (NULL);
 597         }
 598         hp = gethostanswer(buf, n, name, type);
 599         free(buf);
 600         return (hp);
 601 }
 602
 603 struct hostent *
 604 _gethostbydnsaddr(addr, len, af)
 605         const char *addr;       /* XXX should have been def'd as u_char! */
 606         int len, af;
 607 {
 608         const u_char *uaddr = (const u_char *)addr;
 609         static const u_char mapped[] = { 0,0, 0,0, 0,0, 0,0, 0,0, 0xff,0xff };
 610         static const u_char tunnelled[] = { 0,0, 0,0, 0,0, 0,0, 0,0, 0,0 };
 611         int n, size;
 612         querybuf *buf;
 613         struct hostent *hp;
 614         char qbuf[MAXDNAME+1], *qp;
 615 #ifdef SUNSECURITY
 616         struct hostent *rhp;
 617         char **haddr;
 618         u_long old_options;
 619         char hname2[MAXDNAME+1];
 620 #endif /*SUNSECURITY*/
 621
 622         if ((_res.options & RES_INIT) == 0 && res_init() == -1) {
 623                 h_errno = NETDB_INTERNAL;
 624                 return (NULL);
 625         }
 626         if (af == AF_INET6 && len == IN6ADDRSZ &&
 627             (!bcmp(uaddr, mapped, sizeof mapped) ||
 628              !bcmp(uaddr, tunnelled, sizeof tunnelled))) {
 629                 /* Unmap. */
 630                 addr += sizeof mapped;
 631                 uaddr += sizeof mapped;
 632                 af = AF_INET;
 633                 len = INADDRSZ;
 634         }
 635         switch (af) {
 636         case AF_INET:
 637                 size = INADDRSZ;
 638                 break;
 639         case AF_INET6:
 640                 size = IN6ADDRSZ;
 641                 break;
 642         default:
 643                 errno = EAFNOSUPPORT;
 644                 h_errno = NETDB_INTERNAL;
 645                 return (NULL);
 646         }
 647         if (size != len) {
 648                 errno = EINVAL;
 649                 h_errno = NETDB_INTERNAL;
 650                 return (NULL);
 651         }
 652         switch (af) {
 653         case AF_INET:
 654                 (void) sprintf(qbuf, "%u.%u.%u.%u.in-addr.arpa",
 655                                (uaddr[3] & 0xff),
 656                                (uaddr[2] & 0xff),
 657                                (uaddr[1] & 0xff),
 658                                (uaddr[0] & 0xff));
 659                 break;
 660         case AF_INET6:
 661                 qp = qbuf;
 662                 for (n = IN6ADDRSZ - 1; n >= 0; n--) {
 663                         qp += SPRINTF((qp, "%x.%x.",
 664                                        uaddr[n] & 0xf,
 665                                        (uaddr[n] >> 4) & 0xf));
 666                 }
 667                 strlcat(qbuf, "ip6.arpa", sizeof(qbuf));
 668                 break;
 669         default:
 670                 abort();
 671         }
 672         if ((buf = malloc(sizeof(*buf))) == NULL) {
 673                 h_errno = NETDB_INTERNAL;
 674                 return (NULL);
 675         }
 676         n = res_query(qbuf, C_IN, T_PTR, (u_char *)buf->buf, sizeof buf->buf);
 677         if (n < 0 && af == AF_INET6) {
 678                 *qp = '\0';
 679                 strlcat(qbuf, "ip6.int", sizeof(qbuf));
 680                 n = res_query(qbuf, C_IN, T_PTR, (u_char *)buf->buf,
 681                               sizeof buf->buf);
 682         }
 683         if (n < 0) {
 684                 free(buf);
 685                 dprintf("res_query failed (%d)\n", n);
 686                 return (NULL);
 687         }
 688         if (n > sizeof buf->buf) {
 689                 free(buf);
 690                 dprintf("static buffer is too small (%d)\n", n);
 691                 return (NULL);
 692         }
 693         if (!(hp = gethostanswer(buf, n, qbuf, T_PTR))) {
 694                 free(buf);
 695                 return (NULL);  /* h_errno was set by gethostanswer() */
 696         }
 697         free(buf);
 698 #ifdef SUNSECURITY
 699         if (af == AF_INET) {
 700             /*
 701              * turn off search as the name should be absolute,
 702              * 'localhost' should be matched by defnames
 703              */
 704             strncpy(hname2, hp->h_name, MAXDNAME);
 705             hname2[MAXDNAME] = '\0';
 706             old_options = _res.options;
 707             _res.options &= ~RES_DNSRCH;
 708             _res.options |= RES_DEFNAMES;
 709             if (!(rhp = gethostbyname(hname2))) {
 710                 syslog(LOG_NOTICE|LOG_AUTH,
 711                        "gethostbyaddr: No A record for %s (verifying [%s])",
 712                        hname2, inet_ntoa(*((struct in_addr *)addr)));
 713                 _res.options = old_options;
 714                 h_errno = HOST_NOT_FOUND;
 715                 return (NULL);
 716             }
 717             _res.options = old_options;
 718             for (haddr = rhp->h_addr_list; *haddr; haddr++)
 719                 if (!memcmp(*haddr, addr, INADDRSZ))
 720                         break;
 721             if (!*haddr) {
 722                 syslog(LOG_NOTICE|LOG_AUTH,
 723                        "gethostbyaddr: A record of %s != PTR record [%s]",
 724                        hname2, inet_ntoa(*((struct in_addr *)addr)));
 725                 h_errno = HOST_NOT_FOUND;
 726                 return (NULL);
 727             }
 728         }
 729 #endif /*SUNSECURITY*/
 730         hp->h_addrtype = af;
 731         hp->h_length = len;
 732         bcopy(addr, host_addr, len);
 733         h_addr_ptrs[0] = (char *)host_addr;
 734         h_addr_ptrs[1] = NULL;
 735         if (af == AF_INET && (_res.options & RES_USE_INET6)) {
 736                 _map_v4v6_address((char*)host_addr, (char*)host_addr);
 737                 hp->h_addrtype = AF_INET6;
 738                 hp->h_length = IN6ADDRSZ;
 739         }
 740         h_errno = NETDB_SUCCESS;
 741         return (hp);
 742 }
 743
 744 #ifdef RESOLVSORT
 745 static void
 746 addrsort(ap, num)
 747         char **ap;
 748         int num;
 749 {
 750         int i, j;
 751         char **p;
 752         short aval[MAXADDRS];
 753         int needsort = 0;
 754
 755         p = ap;
 756         for (i = 0; i < num; i++, p++) {
 757             for (j = 0 ; (unsigned)j < _res.nsort; j++)
 758                 if (_res.sort_list[j].addr.s_addr ==
 759                     (((struct in_addr *)(*p))->s_addr & _res.sort_list[j].mask))
 760                         break;
 761             aval[i] = j;
 762             if (needsort == 0 && i > 0 && j < aval[i-1])
 763                 needsort = i;
 764         }
 765         if (!needsort)
 766             return;
 767
 768         while (needsort < num) {
 769             for (j = needsort - 1; j >= 0; j--) {
 770                 if (aval[j] > aval[j+1]) {
 771                     char *hp;
 772
 773                     i = aval[j];
 774                     aval[j] = aval[j+1];
 775                     aval[j+1] = i;
 776
 777                     hp = ap[j];
 778                     ap[j] = ap[j+1];
 779                     ap[j+1] = hp;
 780
 781                 } else
 782                     break;
 783             }
 784             needsort++;
 785         }
 786 }
 787 #endif
 788 void
 789 _sethostdnsent(stayopen)
 790         int stayopen;
 791 {
 792         if ((_res.options & RES_INIT) == 0 && res_init() == -1)
 793                 return;
 794         if (stayopen)
 795                 _res.options |= RES_STAYOPEN | RES_USEVC;
 796 }
 797
 798 void
 799 _endhostdnsent()
 800 {
 801         _res.options &= ~(RES_STAYOPEN | RES_USEVC);
 802         res_close();
 803 }