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. Neither the name of the University nor the names of its contributors
  16  *    may be used to endorse or promote products derived from this software
  17  *    without specific prior written permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  29  * SUCH DAMAGE.
  30  * -
  31  * Portions Copyright (c) 1993 by Digital Equipment Corporation.
  32  *
  33  * Permission to use, copy, modify, and distribute this software for any
  34  * purpose with or without fee is hereby granted, provided that the above
  35  * copyright notice and this permission notice appear in all copies, and that
  36  * the name of Digital Equipment Corporation not be used in advertising or
  37  * publicity pertaining to distribution of the document or software without
  38  * specific, written prior permission.
  39  *
  40  * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
  41  * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
  42  * OF MERCHANTABILITY AND FITNESS.   IN NO EVENT SHALL DIGITAL EQUIPMENT
  43  * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
  44  * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
  45  * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
  46  * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
  47  * SOFTWARE.
  48  * -
  49  * --Copyright--
  50  */
  51
  52 #if defined(LIBC_SCCS) && !defined(lint)
  53 static char sccsid[] = "@(#)gethostnamadr.c     8.1 (Berkeley) 6/4/93";
  54 static char fromrcsid[] = "From: Id: gethnamaddr.c,v 8.23 1998/04/07 04:59:46 vixie Exp $";
  55 #endif /* LIBC_SCCS and not lint */
  56 #include <sys/cdefs.h>
  57 __FBSDID("$FreeBSD$");
  58
  59 #include <sys/param.h>
  60 #include <sys/socket.h>
  61 #include <netinet/in.h>
  62 #include <arpa/inet.h>
  63 #include <arpa/nameser.h>
  64
  65 #include <stdio.h>
  66 #include <stdlib.h>
  67 #include <unistd.h>
  68 #include <string.h>
  69 #include <netdb.h>
  70 #include <resolv.h>
  71 #include <ctype.h>
  72 #include <errno.h>
  73 #include <syslog.h>
  74 #include <stdarg.h>
  75 #include <nsswitch.h>
  76
  77 #include "netdb_private.h"
  78 #include "res_config.h"
  79
  80 #define SPRINTF(x) ((size_t)sprintf x)
  81
  82 static const char AskedForGot[] =
  83                 "gethostby*.gethostanswer: asked for \"%s\", got \"%s\"";
  84
  85 #ifdef RESOLVSORT
  86 static void addrsort(char **, int, res_state);
  87 #endif
  88
  89 #ifdef DEBUG
  90 static void dbg_printf(char *, int, res_state) __printflike(1, 0);
  91 #endif
  92
  93 #define MAXPACKET       (64*1024)
  94
  95 typedef union {
  96     HEADER hdr;
  97     u_char buf[MAXPACKET];
  98 } querybuf;
  99
 100 typedef union {
 101     int32_t al;
 102     char ac;
 103 } align;
 104
 105 int _dns_ttl_;
 106
 107 #ifdef DEBUG
 108 static void
 109 dbg_printf(char *msg, int num, res_state res)
 110 {
 111         if (res->options & RES_DEBUG) {
 112                 int save = errno;
 113
 114                 printf(msg, num);
 115                 errno = save;
 116         }
 117 }
 118 #else
 119 # define dbg_printf(msg, num, res) /*nada*/
 120 #endif
 121
 122 #define BOUNDED_INCR(x) \
 123         do { \
 124                 cp += x; \
 125                 if (cp > eom) { \
 126                         RES_SET_H_ERRNO(statp, NO_RECOVERY); \
 127                         return (-1); \
 128                 } \
 129         } while (0)
 130
 131 #define BOUNDS_CHECK(ptr, count) \
 132         do { \
 133                 if ((ptr) + (count) > eom) { \
 134                         RES_SET_H_ERRNO(statp, NO_RECOVERY); \
 135                         return (-1); \
 136                 } \
 137         } while (0)
 138
 139 static int
 140 gethostanswer(const querybuf *answer, int anslen, const char *qname, int qtype,
 141     struct hostent *he, struct hostent_data *hed, res_state statp)
 142 {
 143         const HEADER *hp;
 144         const u_char *cp;
 145         int n;
 146         const u_char *eom, *erdata;
 147         char *bp, *ep, **ap, **hap;
 148         int type, class, ancount, qdcount;
 149         int haveanswer, had_error;
 150         int toobig = 0;
 151         char tbuf[MAXDNAME];
 152         const char *tname;
 153         int (*name_ok)(const char *);
 154
 155         tname = qname;
 156         he->h_name = NULL;
 157         eom = answer->buf + anslen;
 158         switch (qtype) {
 159         case T_A:
 160         case T_AAAA:
 161                 name_ok = res_hnok;
 162                 break;
 163         case T_PTR:
 164                 name_ok = res_dnok;
 165                 break;
 166         default:
 167                 RES_SET_H_ERRNO(statp, NO_RECOVERY);
 168                 return (-1);    /* XXX should be abort(); */
 169         }
 170         /*
 171          * find first satisfactory answer
 172          */
 173         hp = &answer->hdr;
 174         ancount = ntohs(hp->ancount);
 175         qdcount = ntohs(hp->qdcount);
 176         bp = hed->hostbuf;
 177         ep = hed->hostbuf + sizeof hed->hostbuf;
 178         cp = answer->buf;
 179         BOUNDED_INCR(HFIXEDSZ);
 180         if (qdcount != 1) {
 181                 RES_SET_H_ERRNO(statp, NO_RECOVERY);
 182                 return (-1);
 183         }
 184         n = dn_expand(answer->buf, eom, cp, bp, ep - bp);
 185         if ((n < 0) || !(*name_ok)(bp)) {
 186                 RES_SET_H_ERRNO(statp, NO_RECOVERY);
 187                 return (-1);
 188         }
 189         BOUNDED_INCR(n + QFIXEDSZ);
 190         if (qtype == T_A || qtype == T_AAAA) {
 191                 /* res_send() has already verified that the query name is the
 192                  * same as the one we sent; this just gets the expanded name
 193                  * (i.e., with the succeeding search-domain tacked on).
 194                  */
 195                 n = strlen(bp) + 1;             /* for the \0 */
 196                 if (n >= MAXHOSTNAMELEN) {
 197                         RES_SET_H_ERRNO(statp, NO_RECOVERY);
 198                         return (-1);
 199                 }
 200                 he->h_name = bp;
 201                 bp += n;
 202                 /* The qname can be abbreviated, but h_name is now absolute. */
 203                 qname = he->h_name;
 204         }
 205         ap = hed->host_aliases;
 206         *ap = NULL;
 207         he->h_aliases = hed->host_aliases;
 208         hap = hed->h_addr_ptrs;
 209         *hap = NULL;
 210         he->h_addr_list = hed->h_addr_ptrs;
 211         haveanswer = 0;
 212         had_error = 0;
 213         _dns_ttl_ = -1;
 214         while (ancount-- > 0 && cp < eom && !had_error) {
 215                 n = dn_expand(answer->buf, eom, cp, bp, ep - bp);
 216                 if ((n < 0) || !(*name_ok)(bp)) {
 217                         had_error++;
 218                         continue;
 219                 }
 220                 cp += n;                        /* name */
 221                 BOUNDS_CHECK(cp, 3 * INT16SZ + INT32SZ);
 222                 type = _getshort(cp);
 223                 cp += INT16SZ;                  /* type */
 224                 class = _getshort(cp);
 225                 cp += INT16SZ;                  /* class */
 226                 if (qtype == T_A  && type == T_A)
 227                         _dns_ttl_ = _getlong(cp);
 228                 cp += INT32SZ;                  /* TTL */
 229                 n = _getshort(cp);
 230                 cp += INT16SZ;                  /* len */
 231                 BOUNDS_CHECK(cp, n);
 232                 erdata = cp + n;
 233                 if (class != C_IN) {
 234                         /* XXX - debug? syslog? */
 235                         cp += n;
 236                         continue;               /* XXX - had_error++ ? */
 237                 }
 238                 if ((qtype == T_A || qtype == T_AAAA) && type == T_CNAME) {
 239                         if (ap >= &hed->host_aliases[_MAXALIASES-1])
 240                                 continue;
 241                         n = dn_expand(answer->buf, eom, cp, tbuf, sizeof tbuf);
 242                         if ((n < 0) || !(*name_ok)(tbuf)) {
 243                                 had_error++;
 244                                 continue;
 245                         }
 246                         cp += n;
 247                         if (cp != erdata) {
 248                                 RES_SET_H_ERRNO(statp, NO_RECOVERY);
 249                                 return (-1);
 250                         }
 251                         /* Store alias. */
 252                         *ap++ = bp;
 253                         n = strlen(bp) + 1;     /* for the \0 */
 254                         if (n >= MAXHOSTNAMELEN) {
 255                                 had_error++;
 256                                 continue;
 257                         }
 258                         bp += n;
 259                         /* Get canonical name. */
 260                         n = strlen(tbuf) + 1;   /* for the \0 */
 261                         if (n > ep - bp || n >= MAXHOSTNAMELEN) {
 262                                 had_error++;
 263                                 continue;
 264                         }
 265                         strcpy(bp, tbuf);
 266                         he->h_name = bp;
 267                         bp += n;
 268                         continue;
 269                 }
 270                 if (qtype == T_PTR && type == T_CNAME) {
 271                         n = dn_expand(answer->buf, eom, cp, tbuf, sizeof tbuf);
 272                         if (n < 0 || !res_dnok(tbuf)) {
 273                                 had_error++;
 274                                 continue;
 275                         }
 276                         cp += n;
 277                         if (cp != erdata) {
 278                                 RES_SET_H_ERRNO(statp, NO_RECOVERY);
 279                                 return (-1);
 280                         }
 281                         /* Get canonical name. */
 282                         n = strlen(tbuf) + 1;   /* for the \0 */
 283                         if (n > ep - bp || n >= MAXHOSTNAMELEN) {
 284                                 had_error++;
 285                                 continue;
 286                         }
 287                         strcpy(bp, tbuf);
 288                         tname = bp;
 289                         bp += n;
 290                         continue;
 291                 }
 292                 if (type != qtype) {
 293                         if (type != T_SIG && type != ns_t_dname)
 294                                 syslog(LOG_NOTICE|LOG_AUTH,
 295         "gethostby*.gethostanswer: asked for \"%s %s %s\", got type \"%s\"",
 296                                        qname, p_class(C_IN), p_type(qtype),
 297                                        p_type(type));
 298                         cp += n;
 299                         continue;               /* XXX - had_error++ ? */
 300                 }
 301                 switch (type) {
 302                 case T_PTR:
 303                         if (strcasecmp(tname, bp) != 0) {
 304                                 syslog(LOG_NOTICE|LOG_AUTH,
 305                                        AskedForGot, qname, bp);
 306                                 cp += n;
 307                                 continue;       /* XXX - had_error++ ? */
 308                         }
 309                         n = dn_expand(answer->buf, eom, cp, bp, ep - bp);
 310                         if ((n < 0) || !res_hnok(bp)) {
 311                                 had_error++;
 312                                 break;
 313                         }
 314 #if MULTI_PTRS_ARE_ALIASES
 315                         cp += n;
 316                         if (cp != erdata) {
 317                                 RES_SET_H_ERRNO(statp, NO_RECOVERY);
 318                                 return (-1);
 319                         }
 320                         if (!haveanswer)
 321                                 he->h_name = bp;
 322                         else if (ap < &hed->host_aliases[_MAXALIASES-1])
 323                                 *ap++ = bp;
 324                         else
 325                                 n = -1;
 326                         if (n != -1) {
 327                                 n = strlen(bp) + 1;     /* for the \0 */
 328                                 if (n >= MAXHOSTNAMELEN) {
 329                                         had_error++;
 330                                         break;
 331                                 }
 332                                 bp += n;
 333                         }
 334                         break;
 335 #else
 336                         he->h_name = bp;
 337                         if (statp->options & RES_USE_INET6) {
 338                                 n = strlen(bp) + 1;     /* for the \0 */
 339                                 if (n >= MAXHOSTNAMELEN) {
 340                                         had_error++;
 341                                         break;
 342                                 }
 343                                 bp += n;
 344                                 _map_v4v6_hostent(he, &bp, ep);
 345                         }
 346                         RES_SET_H_ERRNO(statp, NETDB_SUCCESS);
 347                         return (0);
 348 #endif
 349                 case T_A:
 350                 case T_AAAA:
 351                         if (strcasecmp(he->h_name, bp) != 0) {
 352                                 syslog(LOG_NOTICE|LOG_AUTH,
 353                                        AskedForGot, he->h_name, bp);
 354                                 cp += n;
 355                                 continue;       /* XXX - had_error++ ? */
 356                         }
 357                         if (n != he->h_length) {
 358                                 cp += n;
 359                                 continue;
 360                         }
 361                         if (!haveanswer) {
 362                                 int nn;
 363
 364                                 he->h_name = bp;
 365                                 nn = strlen(bp) + 1;    /* for the \0 */
 366                                 bp += nn;
 367                         }
 368
 369                         bp += sizeof(align) - ((u_long)bp % sizeof(align));
 370
 371                         if (bp + n >= ep) {
 372                                 dbg_printf("size (%d) too big\n", n, statp);
 373                                 had_error++;
 374                                 continue;
 375                         }
 376                         if (hap >= &hed->h_addr_ptrs[_MAXADDRS-1]) {
 377                                 if (!toobig++)
 378                                         dbg_printf("Too many addresses (%d)\n",
 379                                                 _MAXADDRS, statp);
 380                                 cp += n;
 381                                 continue;
 382                         }
 383                         memcpy(*hap++ = bp, cp, n);
 384                         bp += n;
 385                         cp += n;
 386                         if (cp != erdata) {
 387                                 RES_SET_H_ERRNO(statp, NO_RECOVERY);
 388                                 return (-1);
 389                         }
 390                         break;
 391                 default:
 392                         dbg_printf("Impossible condition (type=%d)\n", type,
 393                             statp);
 394                         RES_SET_H_ERRNO(statp, NO_RECOVERY);
 395                         return (-1);
 396                         /* BIND has abort() here, too risky on bad data */
 397                 }
 398                 if (!had_error)
 399                         haveanswer++;
 400         }
 401         if (haveanswer) {
 402                 *ap = NULL;
 403                 *hap = NULL;
 404 # if defined(RESOLVSORT)
 405                 /*
 406                  * Note: we sort even if host can take only one address
 407                  * in its return structures - should give it the "best"
 408                  * address in that case, not some random one
 409                  */
 410                 if (statp->nsort && haveanswer > 1 && qtype == T_A)
 411                         addrsort(hed->h_addr_ptrs, haveanswer, statp);
 412 # endif /*RESOLVSORT*/
 413                 if (!he->h_name) {
 414                         n = strlen(qname) + 1;  /* for the \0 */
 415                         if (n > ep - bp || n >= MAXHOSTNAMELEN)
 416                                 goto no_recovery;
 417                         strcpy(bp, qname);
 418                         he->h_name = bp;
 419                         bp += n;
 420                 }
 421                 if (statp->options & RES_USE_INET6)
 422                         _map_v4v6_hostent(he, &bp, ep);
 423                 RES_SET_H_ERRNO(statp, NETDB_SUCCESS);
 424                 return (0);
 425         }
 426  no_recovery:
 427         RES_SET_H_ERRNO(statp, NO_RECOVERY);
 428         return (-1);
 429 }
 430
 431 /* XXX: for async DNS resolver in ypserv */
 432 struct hostent *
 433 __dns_getanswer(const char *answer, int anslen, const char *qname, int qtype)
 434 {
 435         struct hostent *he;
 436         struct hostent_data *hed;
 437         int error;
 438         res_state statp;
 439
 440         statp = __res_state();
 441         if ((he = __hostent_init()) == NULL ||
 442             (hed = __hostent_data_init()) == NULL) {
 443                 RES_SET_H_ERRNO(statp, NETDB_INTERNAL);
 444                 return (NULL);
 445         }
 446         switch (qtype) {
 447         case T_AAAA:
 448                 he->h_addrtype = AF_INET6;
 449                 he->h_length = NS_IN6ADDRSZ;
 450                 break;
 451         case T_A:
 452         default:
 453                 he->h_addrtype = AF_INET;
 454                 he->h_length = NS_INADDRSZ;
 455                 break;
 456         }
 457
 458         error = gethostanswer((const querybuf *)answer, anslen, qname, qtype,
 459             he, hed, statp);
 460         return (error == 0) ? he : NULL;
 461 }
 462
 463 int
 464 _dns_gethostbyname(void *rval, void *cb_data, va_list ap)
 465 {
 466         const char *name;
 467         int af;
 468         char *buffer;
 469         size_t buflen;
 470         int *errnop, *h_errnop;
 471         struct hostent *hptr, he;
 472         struct hostent_data *hed;
 473         querybuf *buf;
 474         int n, type, error;
 475         res_state statp;
 476
 477         name = va_arg(ap, const char *);
 478         af = va_arg(ap, int);
 479         hptr = va_arg(ap, struct hostent *);
 480         buffer = va_arg(ap, char *);
 481         buflen = va_arg(ap, size_t);
 482         errnop = va_arg(ap, int *);
 483         h_errnop = va_arg(ap, int *);
 484
 485         *((struct hostent **)rval) = NULL;
 486
 487         statp = __res_state();
 488         if ((hed = __hostent_data_init()) == NULL) {
 489                 RES_SET_H_ERRNO(statp, NETDB_INTERNAL);
 490                 *h_errnop = statp->res_h_errno;
 491                 return (NS_NOTFOUND);
 492         }
 493
 494         he.h_addrtype = af;
 495         switch (af) {
 496         case AF_INET:
 497                 he.h_length = NS_INADDRSZ;
 498                 type = T_A;
 499                 break;
 500         case AF_INET6:
 501                 he.h_length = NS_IN6ADDRSZ;
 502                 type = T_AAAA;
 503                 break;
 504         default:
 505                 RES_SET_H_ERRNO(statp, NETDB_INTERNAL);
 506                 *h_errnop = statp->res_h_errno;
 507                 errno = EAFNOSUPPORT;
 508                 return (NS_UNAVAIL);
 509         }
 510
 511         if ((buf = malloc(sizeof(*buf))) == NULL) {
 512                 RES_SET_H_ERRNO(statp, NETDB_INTERNAL);
 513                 *h_errnop = statp->res_h_errno;
 514                 return (NS_NOTFOUND);
 515         }
 516         n = res_nsearch(statp, name, C_IN, type, buf->buf, sizeof(buf->buf));
 517         if (n < 0) {
 518                 free(buf);
 519                 dbg_printf("res_nsearch failed (%d)\n", n, statp);
 520                 *h_errnop = statp->res_h_errno;
 521                 return (NS_NOTFOUND);
 522         } else if (n > sizeof(buf->buf)) {
 523                 free(buf);
 524                 dbg_printf("static buffer is too small (%d)\n", n, statp);
 525                 *h_errnop = statp->res_h_errno;
 526                 return (NS_UNAVAIL);
 527         }
 528         error = gethostanswer(buf, n, name, type, &he, hed, statp);
 529         free(buf);
 530         if (error != 0) {
 531                 *h_errnop = statp->res_h_errno;
 532                 switch (statp->res_h_errno) {
 533                 case HOST_NOT_FOUND:
 534                         return (NS_NOTFOUND);
 535                 case TRY_AGAIN:
 536                         return (NS_TRYAGAIN);
 537                 default:
 538                         return (NS_UNAVAIL);
 539                 }
 540                 /*NOTREACHED*/
 541         }
 542         if (__copy_hostent(&he, hptr, buffer, buflen) != 0) {
 543                 *errnop = errno;
 544                 RES_SET_H_ERRNO(statp, NETDB_INTERNAL);
 545                 *h_errnop = statp->res_h_errno;
 546                 return (NS_RETURN);
 547         }
 548         RES_SET_H_ERRNO(statp, NETDB_SUCCESS);
 549         *((struct hostent **)rval) = hptr;
 550         return (NS_SUCCESS);
 551 }
 552
 553 int
 554 _dns_gethostbyaddr(void *rval, void *cb_data, va_list ap)
 555 {
 556         const void *addr;
 557         socklen_t len;
 558         int af;
 559         char *buffer;
 560         size_t buflen;
 561         int *errnop, *h_errnop;
 562         const u_char *uaddr;
 563         struct hostent *hptr, he;
 564         struct hostent_data *hed;
 565         int n;
 566         querybuf *buf;
 567         char qbuf[MAXDNAME+1], *qp;
 568         res_state statp;
 569 #ifdef SUNSECURITY
 570         struct hostdata rhd;
 571         struct hostent *rhe;
 572         char **haddr;
 573         u_long old_options;
 574         char hname2[MAXDNAME+1], numaddr[46];
 575         int ret_h_error;
 576 #endif /*SUNSECURITY*/
 577
 578         addr = va_arg(ap, const void *);
 579         len = va_arg(ap, socklen_t);
 580         af = va_arg(ap, int);
 581         hptr = va_arg(ap, struct hostent *);
 582         buffer = va_arg(ap, char *);
 583         buflen = va_arg(ap, size_t);
 584         errnop = va_arg(ap, int *);
 585         h_errnop = va_arg(ap, int *);
 586         uaddr = (const u_char *)addr;
 587
 588         *((struct hostent **)rval) = NULL;
 589
 590         statp = __res_state();
 591         if ((hed = __hostent_data_init()) == NULL) {
 592                 RES_SET_H_ERRNO(statp, NETDB_INTERNAL);
 593                 *h_errnop = statp->res_h_errno;
 594                 return (NS_NOTFOUND);
 595         }
 596
 597         switch (af) {
 598         case AF_INET:
 599                 (void) sprintf(qbuf, "%u.%u.%u.%u.in-addr.arpa",
 600                                (uaddr[3] & 0xff),
 601                                (uaddr[2] & 0xff),
 602                                (uaddr[1] & 0xff),
 603                                (uaddr[0] & 0xff));
 604                 break;
 605         case AF_INET6:
 606                 qp = qbuf;
 607                 for (n = NS_IN6ADDRSZ - 1; n >= 0; n--) {
 608                         qp += SPRINTF((qp, "%x.%x.",
 609                                        uaddr[n] & 0xf,
 610                                        (uaddr[n] >> 4) & 0xf));
 611                 }
 612                 strlcat(qbuf, "ip6.arpa", sizeof(qbuf));
 613                 break;
 614         default:
 615                 abort();
 616         }
 617         if ((buf = malloc(sizeof(*buf))) == NULL) {
 618                 RES_SET_H_ERRNO(statp, NETDB_INTERNAL);
 619                 *h_errnop = statp->res_h_errno;
 620                 return NS_NOTFOUND;
 621         }
 622         n = res_nquery(statp, qbuf, C_IN, T_PTR, (u_char *)buf->buf,
 623             sizeof buf->buf);
 624         if (n < 0) {
 625                 free(buf);
 626                 dbg_printf("res_nquery failed (%d)\n", n, statp);
 627                 *h_errnop = statp->res_h_errno;
 628                 return (NS_UNAVAIL);
 629         }
 630         if (n > sizeof buf->buf) {
 631                 free(buf);
 632                 dbg_printf("static buffer is too small (%d)\n", n, statp);
 633                 *h_errnop = statp->res_h_errno;
 634                 return (NS_UNAVAIL);
 635         }
 636         if (gethostanswer(buf, n, qbuf, T_PTR, &he, hed, statp) != 0) {
 637                 free(buf);
 638                 *h_errnop = statp->res_h_errno;
 639                 switch (statp->res_h_errno) {
 640                 case HOST_NOT_FOUND:
 641                         return (NS_NOTFOUND);
 642                 case TRY_AGAIN:
 643                         return (NS_TRYAGAIN);
 644                 default:
 645                         return (NS_UNAVAIL);
 646                 }
 647                 /*NOTREACHED*/
 648         }
 649         free(buf);
 650 #ifdef SUNSECURITY
 651         if (af == AF_INET) {
 652             /*
 653              * turn off search as the name should be absolute,
 654              * 'localhost' should be matched by defnames
 655              */
 656             strncpy(hname2, he.h_name, MAXDNAME);
 657             hname2[MAXDNAME] = '\0';
 658             old_options = statp->options;
 659             statp->options &= ~RES_DNSRCH;
 660             statp->options |= RES_DEFNAMES;
 661             memset(&rhd, 0, sizeof rhd);
 662             rhe = gethostbyname_r(hname2, &rhd.host, &rhd.data,
 663                 sizeof(rhd.data), &ret_h_error);
 664             if (rhe == NULL) {
 665                 if (inet_ntop(af, addr, numaddr, sizeof(numaddr)) == NULL)
 666                     strlcpy(numaddr, "UNKNOWN", sizeof(numaddr));
 667                 syslog(LOG_NOTICE|LOG_AUTH,
 668                        "gethostbyaddr: No A record for %s (verifying [%s])",
 669                        hname2, numaddr);
 670                 statp->options = old_options;
 671                 RES_SET_H_ERRNO(statp, HOST_NOT_FOUND);
 672                 *h_errnop = statp->res_h_errno;
 673                 return (NS_NOTFOUND);
 674             }
 675             statp->options = old_options;
 676             for (haddr = rhe->h_addr_list; *haddr; haddr++)
 677                 if (!memcmp(*haddr, addr, NS_INADDRSZ))
 678                         break;
 679             if (!*haddr) {
 680                 if (inet_ntop(af, addr, numaddr, sizeof(numaddr)) == NULL)
 681                     strlcpy(numaddr, "UNKNOWN", sizeof(numaddr));
 682                 syslog(LOG_NOTICE|LOG_AUTH,
 683                        "gethostbyaddr: A record of %s != PTR record [%s]",
 684                        hname2, numaddr);
 685                 RES_SET_H_ERRNO(statp, HOST_NOT_FOUND);
 686                 *h_errnop = statp->res_h_errno;
 687                 return (NS_NOTFOUND);
 688             }
 689         }
 690 #endif /*SUNSECURITY*/
 691         he.h_addrtype = af;
 692         he.h_length = len;
 693         memcpy(hed->host_addr, uaddr, len);
 694         hed->h_addr_ptrs[0] = (char *)hed->host_addr;
 695         hed->h_addr_ptrs[1] = NULL;
 696         if (af == AF_INET && (statp->options & RES_USE_INET6)) {
 697                 _map_v4v6_address((char*)hed->host_addr, (char*)hed->host_addr);
 698                 he.h_addrtype = AF_INET6;
 699                 he.h_length = NS_IN6ADDRSZ;
 700         }
 701         if (__copy_hostent(&he, hptr, buffer, buflen) != 0) {
 702                 *errnop = errno;
 703                 RES_SET_H_ERRNO(statp, NETDB_INTERNAL);
 704                 *h_errnop = statp->res_h_errno;
 705                 return (NS_RETURN);
 706         }
 707         RES_SET_H_ERRNO(statp, NETDB_SUCCESS);
 708         *((struct hostent **)rval) = hptr;
 709         return (NS_SUCCESS);
 710 }
 711
 712 #ifdef RESOLVSORT
 713 static void
 714 addrsort(char **ap, int num, res_state res)
 715 {
 716         int i, j;
 717         char **p;
 718         short aval[_MAXADDRS];
 719         int needsort = 0;
 720
 721         p = ap;
 722         for (i = 0; i < num; i++, p++) {
 723             for (j = 0 ; (unsigned)j < res->nsort; j++)
 724                 if (res->sort_list[j].addr.s_addr ==
 725                     (((struct in_addr *)(*p))->s_addr & res->sort_list[j].mask))
 726                         break;
 727             aval[i] = j;
 728             if (needsort == 0 && i > 0 && j < aval[i-1])
 729                 needsort = i;
 730         }
 731         if (!needsort)
 732             return;
 733
 734         while (needsort < num) {
 735             for (j = needsort - 1; j >= 0; j--) {
 736                 if (aval[j] > aval[j+1]) {
 737                     char *hp;
 738
 739                     i = aval[j];
 740                     aval[j] = aval[j+1];
 741                     aval[j+1] = i;
 742
 743                     hp = ap[j];
 744                     ap[j] = ap[j+1];
 745                     ap[j+1] = hp;
 746
 747                 } else
 748                     break;
 749             }
 750             needsort++;
 751         }
 752 }
 753 #endif
 754
 755 void
 756 _sethostdnsent(int stayopen)
 757 {
 758         res_state statp;
 759
 760         statp = __res_state();
 761         if ((statp->options & RES_INIT) == 0 && res_ninit(statp) == -1)
 762                 return;
 763         if (stayopen)
 764                 statp->options |= RES_STAYOPEN | RES_USEVC;
 765 }
 766
 767 void
 768 _endhostdnsent(void)
 769 {
 770         res_state statp;
 771
 772         statp = __res_state();
 773         statp->options &= ~(RES_STAYOPEN | RES_USEVC);
 774         res_nclose(statp);
 775 }