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  * 4. 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/types.h>
  60 #include <sys/param.h>
  61 #include <sys/socket.h>
  62 #include <netinet/in.h>
  63 #include <arpa/inet.h>
  64 #include <arpa/nameser.h>
  65
  66 #include <stdio.h>
  67 #include <stdlib.h>
  68 #include <unistd.h>
  69 #include <string.h>
  70 #include <netdb.h>
  71 #include <resolv.h>
  72 #include <ctype.h>
  73 #include <errno.h>
  74 #include <syslog.h>
  75 #include <stdarg.h>
  76 #include <nsswitch.h>
  77
  78 #include "netdb_private.h"
  79 #include "res_config.h"
  80
  81 #define SPRINTF(x) ((size_t)sprintf x)
  82
  83 static const char AskedForGot[] =
  84                 "gethostby*.gethostanswer: asked for \"%s\", got \"%s\"";
  85
  86 #ifdef RESOLVSORT
  87 static void addrsort(char **, int, res_state);
  88 #endif
  89
  90 #ifdef DEBUG
  91 static void dprintf(char *, int, res_state) __printflike(1, 0);
  92 #endif
  93
  94 #define MAXPACKET       (64*1024)
  95
  96 typedef union {
  97     HEADER hdr;
  98     u_char buf[MAXPACKET];
  99 } querybuf;
 100
 101 typedef union {
 102     int32_t al;
 103     char ac;
 104 } align;
 105
 106 int _dns_ttl_;
 107
 108 #ifdef DEBUG
 109 static void
 110 dprintf(char *msg, int num, res_state res)
 111 {
 112         if (res->options & RES_DEBUG) {
 113                 int save = errno;
 114
 115                 printf(msg, num);
 116                 errno = save;
 117         }
 118 }
 119 #else
 120 # define dprintf(msg, num, res) /*nada*/
 121 #endif
 122
 123 #define BOUNDED_INCR(x) \
 124         do { \
 125                 cp += x; \
 126                 if (cp > eom) { \
 127                         RES_SET_H_ERRNO(statp, NO_RECOVERY); \
 128                         return (-1); \
 129                 } \
 130         } while (0)
 131
 132 #define BOUNDS_CHECK(ptr, count) \
 133         do { \
 134                 if ((ptr) + (count) > eom) { \
 135                         RES_SET_H_ERRNO(statp, NO_RECOVERY); \
 136                         return (-1); \
 137                 } \
 138         } while (0)
 139
 140 static int
 141 gethostanswer(const querybuf *answer, int anslen, const char *qname, int qtype,
 142     struct hostent *he, struct hostent_data *hed, res_state statp)
 143 {
 144         const HEADER *hp;
 145         const u_char *cp;
 146         int n;
 147         const u_char *eom, *erdata;
 148         char *bp, *ep, **ap, **hap;
 149         int type, class, ancount, qdcount;
 150         int haveanswer, had_error;
 151         int toobig = 0;
 152         char tbuf[MAXDNAME];
 153         const char *tname;
 154         int (*name_ok)(const char *);
 155
 156         tname = qname;
 157         he->h_name = NULL;
 158         eom = answer->buf + anslen;
 159         switch (qtype) {
 160         case T_A:
 161         case T_AAAA:
 162                 name_ok = res_hnok;
 163                 break;
 164         case T_PTR:
 165                 name_ok = res_dnok;
 166                 break;
 167         default:
 168                 RES_SET_H_ERRNO(statp, NO_RECOVERY);
 169                 return (-1);    /* XXX should be abort(); */
 170         }
 171         /*
 172          * find first satisfactory answer
 173          */
 174         hp = &answer->hdr;
 175         ancount = ntohs(hp->ancount);
 176         qdcount = ntohs(hp->qdcount);
 177         bp = hed->hostbuf;
 178         ep = hed->hostbuf + sizeof hed->hostbuf;
 179         cp = answer->buf;
 180         BOUNDED_INCR(HFIXEDSZ);
 181         if (qdcount != 1) {
 182                 RES_SET_H_ERRNO(statp, NO_RECOVERY);
 183                 return (-1);
 184         }
 185         n = dn_expand(answer->buf, eom, cp, bp, ep - bp);
 186         if ((n < 0) || !(*name_ok)(bp)) {
 187                 RES_SET_H_ERRNO(statp, NO_RECOVERY);
 188                 return (-1);
 189         }
 190         BOUNDED_INCR(n + QFIXEDSZ);
 191         if (qtype == T_A || qtype == T_AAAA) {
 192                 /* res_send() has already verified that the query name is the
 193                  * same as the one we sent; this just gets the expanded name
 194                  * (i.e., with the succeeding search-domain tacked on).
 195                  */
 196                 n = strlen(bp) + 1;             /* for the \0 */
 197                 if (n >= MAXHOSTNAMELEN) {
 198                         RES_SET_H_ERRNO(statp, NO_RECOVERY);
 199                         return (-1);
 200                 }
 201                 he->h_name = bp;
 202                 bp += n;
 203                 /* The qname can be abbreviated, but h_name is now absolute. */
 204                 qname = he->h_name;
 205         }
 206         ap = hed->host_aliases;
 207         *ap = NULL;
 208         he->h_aliases = hed->host_aliases;
 209         hap = hed->h_addr_ptrs;
 210         *hap = NULL;
 211         he->h_addr_list = hed->h_addr_ptrs;
 212         haveanswer = 0;
 213         had_error = 0;
 214         _dns_ttl_ = -1;
 215         while (ancount-- > 0 && cp < eom && !had_error) {
 216                 n = dn_expand(answer->buf, eom, cp, bp, ep - bp);
 217                 if ((n < 0) || !(*name_ok)(bp)) {
 218                         had_error++;
 219                         continue;
 220                 }
 221                 cp += n;                        /* name */
 222                 BOUNDS_CHECK(cp, 3 * INT16SZ + INT32SZ);
 223                 type = _getshort(cp);
 224                 cp += INT16SZ;                  /* type */
 225                 class = _getshort(cp);
 226                 cp += INT16SZ;                  /* class */
 227                 if (qtype == T_A  && type == T_A)
 228                         _dns_ttl_ = _getlong(cp);
 229                 cp += INT32SZ;                  /* TTL */
 230                 n = _getshort(cp);
 231                 cp += INT16SZ;                  /* len */
 232                 BOUNDS_CHECK(cp, n);
 233                 erdata = cp + n;
 234                 if (class != C_IN) {
 235                         /* XXX - debug? syslog? */
 236                         cp += n;
 237                         continue;               /* XXX - had_error++ ? */
 238                 }
 239                 if ((qtype == T_A || qtype == T_AAAA) && type == T_CNAME) {
 240                         if (ap >= &hed->host_aliases[_MAXALIASES-1])
 241                                 continue;
 242                         n = dn_expand(answer->buf, eom, cp, tbuf, sizeof tbuf);
 243                         if ((n < 0) || !(*name_ok)(tbuf)) {
 244                                 had_error++;
 245                                 continue;
 246                         }
 247                         cp += n;
 248                         if (cp != erdata) {
 249                                 RES_SET_H_ERRNO(statp, NO_RECOVERY);
 250                                 return (-1);
 251                         }
 252                         /* Store alias. */
 253                         *ap++ = bp;
 254                         n = strlen(bp) + 1;     /* for the \0 */
 255                         if (n >= MAXHOSTNAMELEN) {
 256                                 had_error++;
 257                                 continue;
 258                         }
 259                         bp += n;
 260                         /* Get canonical name. */
 261                         n = strlen(tbuf) + 1;   /* for the \0 */
 262                         if (n > ep - bp || n >= MAXHOSTNAMELEN) {
 263                                 had_error++;
 264                                 continue;
 265                         }
 266                         strcpy(bp, tbuf);
 267                         he->h_name = bp;
 268                         bp += n;
 269                         continue;
 270                 }
 271                 if (qtype == T_PTR && type == T_CNAME) {
 272                         n = dn_expand(answer->buf, eom, cp, tbuf, sizeof tbuf);
 273                         if (n < 0 || !res_dnok(tbuf)) {
 274                                 had_error++;
 275                                 continue;
 276                         }
 277                         cp += n;
 278                         if (cp != erdata) {
 279                                 RES_SET_H_ERRNO(statp, NO_RECOVERY);
 280                                 return (-1);
 281                         }
 282                         /* Get canonical name. */
 283                         n = strlen(tbuf) + 1;   /* for the \0 */
 284                         if (n > ep - bp || n >= MAXHOSTNAMELEN) {
 285                                 had_error++;
 286                                 continue;
 287                         }
 288                         strcpy(bp, tbuf);
 289                         tname = bp;
 290                         bp += n;
 291                         continue;
 292                 }
 293                 if (type != qtype) {
 294                         if (type != T_SIG && type != ns_t_dname)
 295                                 syslog(LOG_NOTICE|LOG_AUTH,
 296         "gethostby*.gethostanswer: asked for \"%s %s %s\", got type \"%s\"",
 297                                        qname, p_class(C_IN), p_type(qtype),
 298                                        p_type(type));
 299                         cp += n;
 300                         continue;               /* XXX - had_error++ ? */
 301                 }
 302                 switch (type) {
 303                 case T_PTR:
 304                         if (strcasecmp(tname, bp) != 0) {
 305                                 syslog(LOG_NOTICE|LOG_AUTH,
 306                                        AskedForGot, qname, bp);
 307                                 cp += n;
 308                                 continue;       /* XXX - had_error++ ? */
 309                         }
 310                         n = dn_expand(answer->buf, eom, cp, bp, ep - bp);
 311                         if ((n < 0) || !res_hnok(bp)) {
 312                                 had_error++;
 313                                 break;
 314                         }
 315 #if MULTI_PTRS_ARE_ALIASES
 316                         cp += n;
 317                         if (cp != erdata) {
 318                                 RES_SET_H_ERRNO(statp, NO_RECOVERY);
 319                                 return (-1);
 320                         }
 321                         if (!haveanswer)
 322                                 he->h_name = bp;
 323                         else if (ap < &hed->host_aliases[_MAXALIASES-1])
 324                                 *ap++ = bp;
 325                         else
 326                                 n = -1;
 327                         if (n != -1) {
 328                                 n = strlen(bp) + 1;     /* for the \0 */
 329                                 if (n >= MAXHOSTNAMELEN) {
 330                                         had_error++;
 331                                         break;
 332                                 }
 333                                 bp += n;
 334                         }
 335                         break;
 336 #else
 337                         he->h_name = bp;
 338                         if (statp->options & RES_USE_INET6) {
 339                                 n = strlen(bp) + 1;     /* for the \0 */
 340                                 if (n >= MAXHOSTNAMELEN) {
 341                                         had_error++;
 342                                         break;
 343                                 }
 344                                 bp += n;
 345                                 _map_v4v6_hostent(he, &bp, ep);
 346                         }
 347                         RES_SET_H_ERRNO(statp, NETDB_SUCCESS);
 348                         return (0);
 349 #endif
 350                 case T_A:
 351                 case T_AAAA:
 352                         if (strcasecmp(he->h_name, bp) != 0) {
 353                                 syslog(LOG_NOTICE|LOG_AUTH,
 354                                        AskedForGot, he->h_name, bp);
 355                                 cp += n;
 356                                 continue;       /* XXX - had_error++ ? */
 357                         }
 358                         if (n != he->h_length) {
 359                                 cp += n;
 360                                 continue;
 361                         }
 362                         if (!haveanswer) {
 363                                 int nn;
 364
 365                                 he->h_name = bp;
 366                                 nn = strlen(bp) + 1;    /* for the \0 */
 367                                 bp += nn;
 368                         }
 369
 370                         bp += sizeof(align) - ((u_long)bp % sizeof(align));
 371
 372                         if (bp + n >= ep) {
 373                                 dprintf("size (%d) too big\n", n, statp);
 374                                 had_error++;
 375                                 continue;
 376                         }
 377                         if (hap >= &hed->h_addr_ptrs[_MAXADDRS-1]) {
 378                                 if (!toobig++)
 379                                         dprintf("Too many addresses (%d)\n",
 380                                                 _MAXADDRS, statp);
 381                                 cp += n;
 382                                 continue;
 383                         }
 384                         memcpy(*hap++ = bp, cp, n);
 385                         bp += n;
 386                         cp += n;
 387                         if (cp != erdata) {
 388                                 RES_SET_H_ERRNO(statp, NO_RECOVERY);
 389                                 return (-1);
 390                         }
 391                         break;
 392                 default:
 393                         dprintf("Impossible condition (type=%d)\n", type,
 394                             statp);
 395                         RES_SET_H_ERRNO(statp, NO_RECOVERY);
 396                         return (-1);
 397                         /* BIND has abort() here, too risky on bad data */
 398                 }
 399                 if (!had_error)
 400                         haveanswer++;
 401         }
 402         if (haveanswer) {
 403                 *ap = NULL;
 404                 *hap = NULL;
 405 # if defined(RESOLVSORT)
 406                 /*
 407                  * Note: we sort even if host can take only one address
 408                  * in its return structures - should give it the "best"
 409                  * address in that case, not some random one
 410                  */
 411                 if (statp->nsort && haveanswer > 1 && qtype == T_A)
 412                         addrsort(hed->h_addr_ptrs, haveanswer, statp);
 413 # endif /*RESOLVSORT*/
 414                 if (!he->h_name) {
 415                         n = strlen(qname) + 1;  /* for the \0 */
 416                         if (n > ep - bp || n >= MAXHOSTNAMELEN)
 417                                 goto no_recovery;
 418                         strcpy(bp, qname);
 419                         he->h_name = bp;
 420                         bp += n;
 421                 }
 422                 if (statp->options & RES_USE_INET6)
 423                         _map_v4v6_hostent(he, &bp, ep);
 424                 RES_SET_H_ERRNO(statp, NETDB_SUCCESS);
 425                 return (0);
 426         }
 427  no_recovery:
 428         RES_SET_H_ERRNO(statp, NO_RECOVERY);
 429         return (-1);
 430 }
 431
 432 /* XXX: for async DNS resolver in ypserv */
 433 struct hostent *
 434 __dns_getanswer(const char *answer, int anslen, const char *qname, int qtype)
 435 {
 436         struct hostent *he;
 437         struct hostent_data *hed;
 438         int error;
 439         res_state statp;
 440
 441         statp = __res_state();
 442         if ((he = __hostent_init()) == NULL ||
 443             (hed = __hostent_data_init()) == NULL) {
 444                 RES_SET_H_ERRNO(statp, NETDB_INTERNAL);
 445                 return (NULL);
 446         }
 447         switch (qtype) {
 448         case T_AAAA:
 449                 he->h_addrtype = AF_INET6;
 450                 he->h_length = NS_IN6ADDRSZ;
 451                 break;
 452         case T_A:
 453         default:
 454                 he->h_addrtype = AF_INET;
 455                 he->h_length = NS_INADDRSZ;
 456                 break;
 457         }
 458
 459         error = gethostanswer((const querybuf *)answer, anslen, qname, qtype,
 460             he, hed, statp);
 461         return (error == 0) ? he : NULL;
 462 }
 463
 464 int
 465 _dns_gethostbyname(void *rval, void *cb_data, va_list ap)
 466 {
 467         const char *name;
 468         int af;
 469         char *buffer;
 470         size_t buflen;
 471         int *errnop, *h_errnop;
 472         struct hostent *hptr, he;
 473         struct hostent_data *hed;
 474         querybuf *buf;
 475         int n, type, error;
 476         res_state statp;
 477
 478         name = va_arg(ap, const char *);
 479         af = va_arg(ap, int);
 480         hptr = va_arg(ap, struct hostent *);
 481         buffer = va_arg(ap, char *);
 482         buflen = va_arg(ap, size_t);
 483         errnop = va_arg(ap, int *);
 484         h_errnop = va_arg(ap, int *);
 485
 486         *((struct hostent **)rval) = NULL;
 487
 488         statp = __res_state();
 489         if ((hed = __hostent_data_init()) == NULL) {
 490                 RES_SET_H_ERRNO(statp, NETDB_INTERNAL);
 491                 *h_errnop = statp->res_h_errno;
 492                 return (NS_NOTFOUND);
 493         }
 494
 495         he.h_addrtype = af;
 496         switch (af) {
 497         case AF_INET:
 498                 he.h_length = NS_INADDRSZ;
 499                 type = T_A;
 500                 break;
 501         case AF_INET6:
 502                 he.h_length = NS_IN6ADDRSZ;
 503                 type = T_AAAA;
 504                 break;
 505         default:
 506                 RES_SET_H_ERRNO(statp, NETDB_INTERNAL);
 507                 *h_errnop = statp->res_h_errno;
 508                 errno = EAFNOSUPPORT;
 509                 return (NS_UNAVAIL);
 510         }
 511
 512         if ((buf = malloc(sizeof(*buf))) == NULL) {
 513                 RES_SET_H_ERRNO(statp, NETDB_INTERNAL);
 514                 *h_errnop = statp->res_h_errno;
 515                 return (NS_NOTFOUND);
 516         }
 517         n = res_nsearch(statp, name, C_IN, type, buf->buf, sizeof(buf->buf));
 518         if (n < 0) {
 519                 free(buf);
 520                 dprintf("res_nsearch failed (%d)\n", n, statp);
 521                 *h_errnop = statp->res_h_errno;
 522                 return (NS_NOTFOUND);
 523         } else if (n > sizeof(buf->buf)) {
 524                 free(buf);
 525                 dprintf("static buffer is too small (%d)\n", n, statp);
 526                 *h_errnop = statp->res_h_errno;
 527                 return (NS_UNAVAIL);
 528         }
 529         error = gethostanswer(buf, n, name, type, &he, hed, statp);
 530         free(buf);
 531         if (error != 0) {
 532                 *h_errnop = statp->res_h_errno;
 533                 switch (statp->res_h_errno) {
 534                 case HOST_NOT_FOUND:
 535                         return (NS_NOTFOUND);
 536                 case TRY_AGAIN:
 537                         return (NS_TRYAGAIN);
 538                 default:
 539                         return (NS_UNAVAIL);
 540                 }
 541                 /*NOTREACHED*/
 542         }
 543         if (__copy_hostent(&he, hptr, buffer, buflen) != 0) {
 544                 *errnop = errno;
 545                 RES_SET_H_ERRNO(statp, NETDB_INTERNAL);
 546                 *h_errnop = statp->res_h_errno;
 547                 return (NS_RETURN);
 548         }
 549         RES_SET_H_ERRNO(statp, NETDB_SUCCESS);
 550         *((struct hostent **)rval) = hptr;
 551         return (NS_SUCCESS);
 552 }
 553
 554 int
 555 _dns_gethostbyaddr(void *rval, void *cb_data, va_list ap)
 556 {
 557         const void *addr;
 558         socklen_t len;
 559         int af;
 560         char *buffer;
 561         size_t buflen;
 562         int *errnop, *h_errnop;
 563         const u_char *uaddr;
 564         struct hostent *hptr, he;
 565         struct hostent_data *hed;
 566         int n;
 567         querybuf *buf;
 568         char qbuf[MAXDNAME+1], *qp;
 569         res_state statp;
 570 #ifdef SUNSECURITY
 571         struct hostdata rhd;
 572         struct hostent *rhe;
 573         char **haddr;
 574         u_long old_options;
 575         char hname2[MAXDNAME+1], numaddr[46];
 576         int ret_h_error;
 577 #endif /*SUNSECURITY*/
 578
 579         addr = va_arg(ap, const void *);
 580         len = va_arg(ap, socklen_t);
 581         af = va_arg(ap, int);
 582         hptr = va_arg(ap, struct hostent *);
 583         buffer = va_arg(ap, char *);
 584         buflen = va_arg(ap, size_t);
 585         errnop = va_arg(ap, int *);
 586         h_errnop = va_arg(ap, int *);
 587         uaddr = (const u_char *)addr;
 588
 589         *((struct hostent **)rval) = NULL;
 590
 591         statp = __res_state();
 592         if ((hed = __hostent_data_init()) == NULL) {
 593                 RES_SET_H_ERRNO(statp, NETDB_INTERNAL);
 594                 *h_errnop = statp->res_h_errno;
 595                 return (NS_NOTFOUND);
 596         }
 597
 598         switch (af) {
 599         case AF_INET:
 600                 (void) sprintf(qbuf, "%u.%u.%u.%u.in-addr.arpa",
 601                                (uaddr[3] & 0xff),
 602                                (uaddr[2] & 0xff),
 603                                (uaddr[1] & 0xff),
 604                                (uaddr[0] & 0xff));
 605                 break;
 606         case AF_INET6:
 607                 qp = qbuf;
 608                 for (n = NS_IN6ADDRSZ - 1; n >= 0; n--) {
 609                         qp += SPRINTF((qp, "%x.%x.",
 610                                        uaddr[n] & 0xf,
 611                                        (uaddr[n] >> 4) & 0xf));
 612                 }
 613                 strlcat(qbuf, "ip6.arpa", sizeof(qbuf));
 614                 break;
 615         default:
 616                 abort();
 617         }
 618         if ((buf = malloc(sizeof(*buf))) == NULL) {
 619                 RES_SET_H_ERRNO(statp, NETDB_INTERNAL);
 620                 *h_errnop = statp->res_h_errno;
 621                 return NS_NOTFOUND;
 622         }
 623         n = res_nquery(statp, qbuf, C_IN, T_PTR, (u_char *)buf->buf,
 624             sizeof buf->buf);
 625         if (n < 0) {
 626                 free(buf);
 627                 dprintf("res_nquery failed (%d)\n", n, statp);
 628                 *h_errnop = statp->res_h_errno;
 629                 return (NS_UNAVAIL);
 630         }
 631         if (n > sizeof buf->buf) {
 632                 free(buf);
 633                 dprintf("static buffer is too small (%d)\n", n, statp);
 634                 *h_errnop = statp->res_h_errno;
 635                 return (NS_UNAVAIL);
 636         }
 637         if (gethostanswer(buf, n, qbuf, T_PTR, &he, hed, statp) != 0) {
 638                 free(buf);
 639                 *h_errnop = statp->res_h_errno;
 640                 switch (statp->res_h_errno) {
 641                 case HOST_NOT_FOUND:
 642                         return (NS_NOTFOUND);
 643                 case TRY_AGAIN:
 644                         return (NS_TRYAGAIN);
 645                 default:
 646                         return (NS_UNAVAIL);
 647                 }
 648                 /*NOTREACHED*/
 649         }
 650         free(buf);
 651 #ifdef SUNSECURITY
 652         if (af == AF_INET) {
 653             /*
 654              * turn off search as the name should be absolute,
 655              * 'localhost' should be matched by defnames
 656              */
 657             strncpy(hname2, he.h_name, MAXDNAME);
 658             hname2[MAXDNAME] = '\0';
 659             old_options = statp->options;
 660             statp->options &= ~RES_DNSRCH;
 661             statp->options |= RES_DEFNAMES;
 662             memset(&rhd, 0, sizeof rhd);
 663             rhe = gethostbyname_r(hname2, &rhd.host, &rhd.data,
 664                 sizeof(rhd.data), &ret_h_error);
 665             if (rhe == NULL) {
 666                 if (inet_ntop(af, addr, numaddr, sizeof(numaddr)) == NULL)
 667                     strlcpy(numaddr, "UNKNOWN", sizeof(numaddr));
 668                 syslog(LOG_NOTICE|LOG_AUTH,
 669                        "gethostbyaddr: No A record for %s (verifying [%s])",
 670                        hname2, numaddr);
 671                 statp->options = old_options;
 672                 RES_SET_H_ERRNO(statp, HOST_NOT_FOUND);
 673                 *h_errnop = statp->res_h_errno;
 674                 return (NS_NOTFOUND);
 675             }
 676             statp->options = old_options;
 677             for (haddr = rhe->h_addr_list; *haddr; haddr++)
 678                 if (!memcmp(*haddr, addr, NS_INADDRSZ))
 679                         break;
 680             if (!*haddr) {
 681                 if (inet_ntop(af, addr, numaddr, sizeof(numaddr)) == NULL)
 682                     strlcpy(numaddr, "UNKNOWN", sizeof(numaddr));
 683                 syslog(LOG_NOTICE|LOG_AUTH,
 684                        "gethostbyaddr: A record of %s != PTR record [%s]",
 685                        hname2, numaddr);
 686                 RES_SET_H_ERRNO(statp, HOST_NOT_FOUND);
 687                 *h_errnop = statp->res_h_errno;
 688                 return (NS_NOTFOUND);
 689             }
 690         }
 691 #endif /*SUNSECURITY*/
 692         he.h_addrtype = af;
 693         he.h_length = len;
 694         memcpy(hed->host_addr, uaddr, len);
 695         hed->h_addr_ptrs[0] = (char *)hed->host_addr;
 696         hed->h_addr_ptrs[1] = NULL;
 697         if (af == AF_INET && (statp->options & RES_USE_INET6)) {
 698                 _map_v4v6_address((char*)hed->host_addr, (char*)hed->host_addr);
 699                 he.h_addrtype = AF_INET6;
 700                 he.h_length = NS_IN6ADDRSZ;
 701         }
 702         if (__copy_hostent(&he, hptr, buffer, buflen) != 0) {
 703                 *errnop = errno;
 704                 RES_SET_H_ERRNO(statp, NETDB_INTERNAL);
 705                 *h_errnop = statp->res_h_errno;
 706                 return (NS_RETURN);
 707         }
 708         RES_SET_H_ERRNO(statp, NETDB_SUCCESS);
 709         *((struct hostent **)rval) = hptr;
 710         return (NS_SUCCESS);
 711 }
 712
 713 #ifdef RESOLVSORT
 714 static void
 715 addrsort(char **ap, int num, res_state res)
 716 {
 717         int i, j;
 718         char **p;
 719         short aval[_MAXADDRS];
 720         int needsort = 0;
 721
 722         p = ap;
 723         for (i = 0; i < num; i++, p++) {
 724             for (j = 0 ; (unsigned)j < res->nsort; j++)
 725                 if (res->sort_list[j].addr.s_addr ==
 726                     (((struct in_addr *)(*p))->s_addr & res->sort_list[j].mask))
 727                         break;
 728             aval[i] = j;
 729             if (needsort == 0 && i > 0 && j < aval[i-1])
 730                 needsort = i;
 731         }
 732         if (!needsort)
 733             return;
 734
 735         while (needsort < num) {
 736             for (j = needsort - 1; j >= 0; j--) {
 737                 if (aval[j] > aval[j+1]) {
 738                     char *hp;
 739
 740                     i = aval[j];
 741                     aval[j] = aval[j+1];
 742                     aval[j+1] = i;
 743
 744                     hp = ap[j];
 745                     ap[j] = ap[j+1];
 746                     ap[j+1] = hp;
 747
 748                 } else
 749                     break;
 750             }
 751             needsort++;
 752         }
 753 }
 754 #endif
 755
 756 void
 757 _sethostdnsent(int stayopen)
 758 {
 759         res_state statp;
 760
 761         statp = __res_state();
 762         if ((statp->options & RES_INIT) == 0 && res_ninit(statp) == -1)
 763                 return;
 764         if (stayopen)
 765                 statp->options |= RES_STAYOPEN | RES_USEVC;
 766 }
 767
 768 void
 769 _endhostdnsent(void)
 770 {
 771         res_state statp;
 772
 773         statp = __res_state();
 774         statp->options &= ~(RES_STAYOPEN | RES_USEVC);
 775         res_nclose(statp);
 776 }