lib/libc/net/gethostbydns.c

   1 /*-
   2  * SPDX-License-Identifier: BSD-3-Clause
   3  *
   4  * ++Copyright++ 1985, 1988, 1993
   5  * -
   6  * Copyright (c) 1985, 1988, 1993
   7  *      The Regents of the University of California.  All rights reserved.
   8  *
   9  * Redistribution and use in source and binary forms, with or without
  10  * modification, are permitted provided that the following conditions
  11  * are met:
  12  * 1. Redistributions of source code must retain the above copyright
  13  *    notice, this list of conditions and the following disclaimer.
  14  * 2. Redistributions in binary form must reproduce the above copyright
  15  *    notice, this list of conditions and the following disclaimer in the
  16  *    documentation and/or other materials provided with the distribution.
  17  * 3. Neither the name of the University nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  * -
  33  * Portions Copyright (c) 1993 by Digital Equipment Corporation.
  34  *
  35  * Permission to use, copy, modify, and distribute this software for any
  36  * purpose with or without fee is hereby granted, provided that the above
  37  * copyright notice and this permission notice appear in all copies, and that
  38  * the name of Digital Equipment Corporation not be used in advertising or
  39  * publicity pertaining to distribution of the document or software without
  40  * specific, written prior permission.
  41  *
  42  * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
  43  * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
  44  * OF MERCHANTABILITY AND FITNESS.   IN NO EVENT SHALL DIGITAL EQUIPMENT
  45  * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
  46  * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
  47  * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
  48  * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
  49  * SOFTWARE.
  50  * -
  51  * --Copyright--
  52  */
  53
  54 #if defined(LIBC_SCCS) && !defined(lint)
  55 static char sccsid[] = "@(#)gethostnamadr.c     8.1 (Berkeley) 6/4/93";
  56 static char fromrcsid[] = "From: Id: gethnamaddr.c,v 8.23 1998/04/07 04:59:46 vixie Exp $";
  57 #endif /* LIBC_SCCS and not lint */
  58 #include <sys/cdefs.h>
  59 __FBSDID("$FreeBSD$");
  60
  61 #include <sys/param.h>
  62 #include <sys/socket.h>
  63 #include <netinet/in.h>
  64 #include <arpa/inet.h>
  65 #include <arpa/nameser.h>
  66
  67 #include <stdio.h>
  68 #include <stdlib.h>
  69 #include <unistd.h>
  70 #include <string.h>
  71 #include <netdb.h>
  72 #include <resolv.h>
  73 #include <ctype.h>
  74 #include <errno.h>
  75 #include <syslog.h>
  76 #include <stdarg.h>
  77 #include <nsswitch.h>
  78
  79 #include "netdb_private.h"
  80 #include "res_config.h"
  81
  82 #define SPRINTF(x) ((size_t)sprintf x)
  83
  84 static const char AskedForGot[] =
  85                 "gethostby*.gethostanswer: asked for \"%s\", got \"%s\"";
  86
  87 #ifdef RESOLVSORT
  88 static void addrsort(char **, int, res_state);
  89 #endif
  90
  91 #ifdef DEBUG
  92 static void dbg_printf(char *, int, res_state) __printflike(1, 0);
  93 #endif
  94
  95 #define MAXPACKET       (64*1024)
  96
  97 typedef union {
  98     HEADER hdr;
  99     u_char buf[MAXPACKET];
 100 } querybuf;
 101
 102 typedef union {
 103     int32_t al;
 104     char ac;
 105 } align;
 106
 107 int _dns_ttl_;
 108
 109 #ifdef DEBUG
 110 static void
 111 dbg_printf(char *msg, int num, res_state res)
 112 {
 113         if (res->options & RES_DEBUG) {
 114                 int save = errno;
 115
 116                 printf(msg, num);
 117                 errno = save;
 118         }
 119 }
 120 #else
 121 # define dbg_printf(msg, num, res) /*nada*/
 122 #endif
 123
 124 #define BOUNDED_INCR(x) \
 125         do { \
 126                 cp += x; \
 127                 if (cp > eom) { \
 128                         RES_SET_H_ERRNO(statp, NO_RECOVERY); \
 129                         return (-1); \
 130                 } \
 131         } while (0)
 132
 133 #define BOUNDS_CHECK(ptr, count) \
 134         do { \
 135                 if ((ptr) + (count) > eom) { \
 136                         RES_SET_H_ERRNO(statp, NO_RECOVERY); \
 137                         return (-1); \
 138                 } \
 139         } while (0)
 140
 141 static int
 142 gethostanswer(const querybuf *answer, int anslen, const char *qname, int qtype,
 143     struct hostent *he, struct hostent_data *hed, res_state statp)
 144 {
 145         const HEADER *hp;
 146         const u_char *cp;
 147         int n;
 148         const u_char *eom, *erdata;
 149         char *bp, *ep, **ap, **hap;
 150         int type, class, ancount, qdcount;
 151         int haveanswer, had_error;
 152         int toobig = 0;
 153         char tbuf[MAXDNAME];
 154         const char *tname;
 155         int (*name_ok)(const char *);
 156
 157         tname = qname;
 158         he->h_name = NULL;
 159         eom = answer->buf + anslen;
 160         switch (qtype) {
 161         case T_A:
 162         case T_AAAA:
 163                 name_ok = res_hnok;
 164                 break;
 165         case T_PTR:
 166                 name_ok = res_dnok;
 167                 break;
 168         default:
 169                 RES_SET_H_ERRNO(statp, NO_RECOVERY);
 170                 return (-1);    /* XXX should be abort(); */
 171         }
 172         /*
 173          * find first satisfactory answer
 174          */
 175         hp = &answer->hdr;
 176         ancount = ntohs(hp->ancount);
 177         qdcount = ntohs(hp->qdcount);
 178         bp = hed->hostbuf;
 179         ep = hed->hostbuf + sizeof hed->hostbuf;
 180         cp = answer->buf;
 181         BOUNDED_INCR(HFIXEDSZ);
 182         if (qdcount != 1) {
 183                 RES_SET_H_ERRNO(statp, NO_RECOVERY);
 184                 return (-1);
 185         }
 186         n = dn_expand(answer->buf, eom, cp, bp, ep - bp);
 187         if ((n < 0) || !(*name_ok)(bp)) {
 188                 RES_SET_H_ERRNO(statp, NO_RECOVERY);
 189                 return (-1);
 190         }
 191         BOUNDED_INCR(n + QFIXEDSZ);
 192         if (qtype == T_A || qtype == T_AAAA) {
 193                 /* res_send() has already verified that the query name is the
 194                  * same as the one we sent; this just gets the expanded name
 195                  * (i.e., with the succeeding search-domain tacked on).
 196                  */
 197                 n = strlen(bp) + 1;             /* for the \0 */
 198                 if (n >= MAXHOSTNAMELEN) {
 199                         RES_SET_H_ERRNO(statp, NO_RECOVERY);
 200                         return (-1);
 201                 }
 202                 he->h_name = bp;
 203                 bp += n;
 204                 /* The qname can be abbreviated, but h_name is now absolute. */
 205                 qname = he->h_name;
 206         }
 207         ap = hed->host_aliases;
 208         *ap = NULL;
 209         he->h_aliases = hed->host_aliases;
 210         hap = hed->h_addr_ptrs;
 211         *hap = NULL;
 212         he->h_addr_list = hed->h_addr_ptrs;
 213         haveanswer = 0;
 214         had_error = 0;
 215         _dns_ttl_ = -1;
 216         while (ancount-- > 0 && cp < eom && !had_error) {
 217                 n = dn_expand(answer->buf, eom, cp, bp, ep - bp);
 218                 if ((n < 0) || !(*name_ok)(bp)) {
 219                         had_error++;
 220                         continue;
 221                 }
 222                 cp += n;                        /* name */
 223                 BOUNDS_CHECK(cp, 3 * INT16SZ + INT32SZ);
 224                 type = _getshort(cp);
 225                 cp += INT16SZ;                  /* type */
 226                 class = _getshort(cp);
 227                 cp += INT16SZ;                  /* class */
 228                 if (qtype == T_A  && type == T_A)
 229                         _dns_ttl_ = _getlong(cp);
 230                 cp += INT32SZ;                  /* TTL */
 231                 n = _getshort(cp);
 232                 cp += INT16SZ;                  /* len */
 233                 BOUNDS_CHECK(cp, n);
 234                 erdata = cp + n;
 235                 if (class != C_IN) {
 236                         /* XXX - debug? syslog? */
 237                         cp += n;
 238                         continue;               /* XXX - had_error++ ? */
 239                 }
 240                 if ((qtype == T_A || qtype == T_AAAA) && type == T_CNAME) {
 241                         if (ap >= &hed->host_aliases[_MAXALIASES-1])
 242                                 continue;
 243                         n = dn_expand(answer->buf, eom, cp, tbuf, sizeof tbuf);
 244                         if ((n < 0) || !(*name_ok)(tbuf)) {
 245                                 had_error++;
 246                                 continue;
 247                         }
 248                         cp += n;
 249                         if (cp != erdata) {
 250                                 RES_SET_H_ERRNO(statp, NO_RECOVERY);
 251                                 return (-1);
 252                         }
 253                         /* Store alias. */
 254                         *ap++ = bp;
 255                         n = strlen(bp) + 1;     /* for the \0 */
 256                         if (n >= MAXHOSTNAMELEN) {
 257                                 had_error++;
 258                                 continue;
 259                         }
 260                         bp += n;
 261                         /* Get canonical name. */
 262                         n = strlen(tbuf) + 1;   /* for the \0 */
 263                         if (n > ep - bp || n >= MAXHOSTNAMELEN) {
 264                                 had_error++;
 265                                 continue;
 266                         }
 267                         strcpy(bp, tbuf);
 268                         he->h_name = bp;
 269                         bp += n;
 270                         continue;
 271                 }
 272                 if (qtype == T_PTR && type == T_CNAME) {
 273                         n = dn_expand(answer->buf, eom, cp, tbuf, sizeof tbuf);
 274                         if (n < 0 || !res_dnok(tbuf)) {
 275                                 had_error++;
 276                                 continue;
 277                         }
 278                         cp += n;
 279                         if (cp != erdata) {
 280                                 RES_SET_H_ERRNO(statp, NO_RECOVERY);
 281                                 return (-1);
 282                         }
 283                         /* Get canonical name. */
 284                         n = strlen(tbuf) + 1;   /* for the \0 */
 285                         if (n > ep - bp || n >= MAXHOSTNAMELEN) {
 286                                 had_error++;
 287                                 continue;
 288                         }
 289                         strcpy(bp, tbuf);
 290                         tname = bp;
 291                         bp += n;
 292                         continue;
 293                 }
 294                 if (type != qtype) {
 295                         if (type != T_SIG && type != ns_t_dname)
 296                                 syslog(LOG_NOTICE|LOG_AUTH,
 297         "gethostby*.gethostanswer: asked for \"%s %s %s\", got type \"%s\"",
 298                                        qname, p_class(C_IN), p_type(qtype),
 299                                        p_type(type));
 300                         cp += n;
 301                         continue;               /* XXX - had_error++ ? */
 302                 }
 303                 switch (type) {
 304                 case T_PTR:
 305                         if (strcasecmp(tname, bp) != 0) {
 306                                 syslog(LOG_NOTICE|LOG_AUTH,
 307                                        AskedForGot, qname, bp);
 308                                 cp += n;
 309                                 continue;       /* XXX - had_error++ ? */
 310                         }
 311                         n = dn_expand(answer->buf, eom, cp, bp, ep - bp);
 312                         if ((n < 0) || !res_hnok(bp)) {
 313                                 had_error++;
 314                                 break;
 315                         }
 316 #if MULTI_PTRS_ARE_ALIASES
 317                         cp += n;
 318                         if (cp != erdata) {
 319                                 RES_SET_H_ERRNO(statp, NO_RECOVERY);
 320                                 return (-1);
 321                         }
 322                         if (!haveanswer)
 323                                 he->h_name = bp;
 324                         else if (ap < &hed->host_aliases[_MAXALIASES-1])
 325                                 *ap++ = bp;
 326                         else
 327                                 n = -1;
 328                         if (n != -1) {
 329                                 n = strlen(bp) + 1;     /* for the \0 */
 330                                 if (n >= MAXHOSTNAMELEN) {
 331                                         had_error++;
 332                                         break;
 333                                 }
 334                                 bp += n;
 335                         }
 336                         break;
 337 #else
 338                         he->h_name = bp;
 339                         if (statp->options & RES_USE_INET6) {
 340                                 n = strlen(bp) + 1;     /* for the \0 */
 341                                 if (n >= MAXHOSTNAMELEN) {
 342                                         had_error++;
 343                                         break;
 344                                 }
 345                                 bp += n;
 346                                 _map_v4v6_hostent(he, &bp, ep);
 347                         }
 348                         RES_SET_H_ERRNO(statp, NETDB_SUCCESS);
 349                         return (0);
 350 #endif
 351                 case T_A:
 352                 case T_AAAA:
 353                         if (strcasecmp(he->h_name, bp) != 0) {
 354                                 syslog(LOG_NOTICE|LOG_AUTH,
 355                                        AskedForGot, he->h_name, bp);
 356                                 cp += n;
 357                                 continue;       /* XXX - had_error++ ? */
 358                         }
 359                         if (n != he->h_length) {
 360                                 cp += n;
 361                                 continue;
 362                         }
 363                         if (!haveanswer) {
 364                                 int nn;
 365
 366                                 he->h_name = bp;
 367                                 nn = strlen(bp) + 1;    /* for the \0 */
 368                                 bp += nn;
 369                         }
 370
 371                         bp += sizeof(align) - ((u_long)bp % sizeof(align));
 372
 373                         if (bp + n >= ep) {
 374                                 dbg_printf("size (%d) too big\n", n, statp);
 375                                 had_error++;
 376                                 continue;
 377                         }
 378                         if (hap >= &hed->h_addr_ptrs[_MAXADDRS-1]) {
 379                                 if (!toobig++)
 380                                         dbg_printf("Too many addresses (%d)\n",
 381                                                 _MAXADDRS, statp);
 382                                 cp += n;
 383                                 continue;
 384                         }
 385                         memcpy(*hap++ = bp, cp, n);
 386                         bp += n;
 387                         cp += n;
 388                         if (cp != erdata) {
 389                                 RES_SET_H_ERRNO(statp, NO_RECOVERY);
 390                                 return (-1);
 391                         }
 392                         break;
 393                 default:
 394                         dbg_printf("Impossible condition (type=%d)\n", type,
 395                             statp);
 396                         RES_SET_H_ERRNO(statp, NO_RECOVERY);
 397                         return (-1);
 398                         /* BIND has abort() here, too risky on bad data */
 399                 }
 400                 if (!had_error)
 401                         haveanswer++;
 402         }
 403         if (haveanswer) {
 404                 *ap = NULL;
 405                 *hap = NULL;
 406 # if defined(RESOLVSORT)
 407                 /*
 408                  * Note: we sort even if host can take only one address
 409                  * in its return structures - should give it the "best"
 410                  * address in that case, not some random one
 411                  */
 412                 if (statp->nsort && haveanswer > 1 && qtype == T_A)
 413                         addrsort(hed->h_addr_ptrs, haveanswer, statp);
 414 # endif /*RESOLVSORT*/
 415                 if (!he->h_name) {
 416                         n = strlen(qname) + 1;  /* for the \0 */
 417                         if (n > ep - bp || n >= MAXHOSTNAMELEN)
 418                                 goto no_recovery;
 419                         strcpy(bp, qname);
 420                         he->h_name = bp;
 421                         bp += n;
 422                 }
 423                 if (statp->options & RES_USE_INET6)
 424                         _map_v4v6_hostent(he, &bp, ep);
 425                 RES_SET_H_ERRNO(statp, NETDB_SUCCESS);
 426                 return (0);
 427         }
 428  no_recovery:
 429         RES_SET_H_ERRNO(statp, NO_RECOVERY);
 430         return (-1);
 431 }
 432
 433 /* XXX: for async DNS resolver in ypserv */
 434 struct hostent *
 435 __dns_getanswer(const char *answer, int anslen, const char *qname, int qtype)
 436 {
 437         struct hostent *he;
 438         struct hostent_data *hed;
 439         int error;
 440         res_state statp;
 441
 442         statp = __res_state();
 443         if ((he = __hostent_init()) == NULL ||
 444             (hed = __hostent_data_init()) == NULL) {
 445                 RES_SET_H_ERRNO(statp, NETDB_INTERNAL);
 446                 return (NULL);
 447         }
 448         switch (qtype) {
 449         case T_AAAA:
 450                 he->h_addrtype = AF_INET6;
 451                 he->h_length = NS_IN6ADDRSZ;
 452                 break;
 453         case T_A:
 454         default:
 455                 he->h_addrtype = AF_INET;
 456                 he->h_length = NS_INADDRSZ;
 457                 break;
 458         }
 459
 460         error = gethostanswer((const querybuf *)answer, anslen, qname, qtype,
 461             he, hed, statp);
 462         return (error == 0) ? he : NULL;
 463 }
 464
 465 int
 466 _dns_gethostbyname(void *rval, void *cb_data, va_list ap)
 467 {
 468         const char *name;
 469         int af;
 470         char *buffer;
 471         size_t buflen;
 472         int *errnop, *h_errnop;
 473         struct hostent *hptr, he;
 474         struct hostent_data *hed;
 475         querybuf *buf;
 476         int n, type, error;
 477         res_state statp;
 478
 479         name = va_arg(ap, const char *);
 480         af = va_arg(ap, int);
 481         hptr = va_arg(ap, struct hostent *);
 482         buffer = va_arg(ap, char *);
 483         buflen = va_arg(ap, size_t);
 484         errnop = va_arg(ap, int *);
 485         h_errnop = va_arg(ap, int *);
 486
 487         *((struct hostent **)rval) = NULL;
 488
 489         statp = __res_state();
 490         if ((hed = __hostent_data_init()) == NULL) {
 491                 RES_SET_H_ERRNO(statp, NETDB_INTERNAL);
 492                 *h_errnop = statp->res_h_errno;
 493                 return (NS_NOTFOUND);
 494         }
 495
 496         he.h_addrtype = af;
 497         switch (af) {
 498         case AF_INET:
 499                 he.h_length = NS_INADDRSZ;
 500                 type = T_A;
 501                 break;
 502         case AF_INET6:
 503                 he.h_length = NS_IN6ADDRSZ;
 504                 type = T_AAAA;
 505                 break;
 506         default:
 507                 RES_SET_H_ERRNO(statp, NETDB_INTERNAL);
 508                 *h_errnop = statp->res_h_errno;
 509                 errno = EAFNOSUPPORT;
 510                 return (NS_UNAVAIL);
 511         }
 512
 513         if ((buf = malloc(sizeof(*buf))) == NULL) {
 514                 RES_SET_H_ERRNO(statp, NETDB_INTERNAL);
 515                 *h_errnop = statp->res_h_errno;
 516                 return (NS_NOTFOUND);
 517         }
 518         n = res_nsearch(statp, name, C_IN, type, buf->buf, sizeof(buf->buf));
 519         if (n < 0) {
 520                 free(buf);
 521                 dbg_printf("res_nsearch failed (%d)\n", n, statp);
 522                 *h_errnop = statp->res_h_errno;
 523                 return (NS_NOTFOUND);
 524         } else if (n > sizeof(buf->buf)) {
 525                 free(buf);
 526                 dbg_printf("static buffer is too small (%d)\n", n, statp);
 527                 *h_errnop = statp->res_h_errno;
 528                 return (NS_UNAVAIL);
 529         }
 530         error = gethostanswer(buf, n, name, type, &he, hed, statp);
 531         free(buf);
 532         if (error != 0) {
 533                 *h_errnop = statp->res_h_errno;
 534                 switch (statp->res_h_errno) {
 535                 case HOST_NOT_FOUND:
 536                         return (NS_NOTFOUND);
 537                 case TRY_AGAIN:
 538                         return (NS_TRYAGAIN);
 539                 default:
 540                         return (NS_UNAVAIL);
 541                 }
 542                 /*NOTREACHED*/
 543         }
 544         if (__copy_hostent(&he, hptr, buffer, buflen) != 0) {
 545                 *errnop = errno;
 546                 RES_SET_H_ERRNO(statp, NETDB_INTERNAL);
 547                 *h_errnop = statp->res_h_errno;
 548                 return (NS_RETURN);
 549         }
 550         RES_SET_H_ERRNO(statp, NETDB_SUCCESS);
 551         *((struct hostent **)rval) = hptr;
 552         return (NS_SUCCESS);
 553 }
 554
 555 int
 556 _dns_gethostbyaddr(void *rval, void *cb_data, va_list ap)
 557 {
 558         const void *addr;
 559         socklen_t len;
 560         int af;
 561         char *buffer;
 562         size_t buflen;
 563         int *errnop, *h_errnop;
 564         const u_char *uaddr;
 565         struct hostent *hptr, he;
 566         struct hostent_data *hed;
 567         int n;
 568         querybuf *buf;
 569         char qbuf[MAXDNAME+1], *qp;
 570         res_state statp;
 571 #ifdef SUNSECURITY
 572         struct hostdata rhd;
 573         struct hostent *rhe;
 574         char **haddr;
 575         u_long old_options;
 576         char hname2[MAXDNAME+1], numaddr[46];
 577         int ret_h_error;
 578 #endif /*SUNSECURITY*/
 579
 580         addr = va_arg(ap, const void *);
 581         len = va_arg(ap, socklen_t);
 582         af = va_arg(ap, int);
 583         hptr = va_arg(ap, struct hostent *);
 584         buffer = va_arg(ap, char *);
 585         buflen = va_arg(ap, size_t);
 586         errnop = va_arg(ap, int *);
 587         h_errnop = va_arg(ap, int *);
 588         uaddr = (const u_char *)addr;
 589
 590         *((struct hostent **)rval) = NULL;
 591
 592         statp = __res_state();
 593         if ((hed = __hostent_data_init()) == NULL) {
 594                 RES_SET_H_ERRNO(statp, NETDB_INTERNAL);
 595                 *h_errnop = statp->res_h_errno;
 596                 return (NS_NOTFOUND);
 597         }
 598
 599         switch (af) {
 600         case AF_INET:
 601                 (void) sprintf(qbuf, "%u.%u.%u.%u.in-addr.arpa",
 602                                (uaddr[3] & 0xff),
 603                                (uaddr[2] & 0xff),
 604                                (uaddr[1] & 0xff),
 605                                (uaddr[0] & 0xff));
 606                 break;
 607         case AF_INET6:
 608                 qp = qbuf;
 609                 for (n = NS_IN6ADDRSZ - 1; n >= 0; n--) {
 610                         qp += SPRINTF((qp, "%x.%x.",
 611                                        uaddr[n] & 0xf,
 612                                        (uaddr[n] >> 4) & 0xf));
 613                 }
 614                 strlcat(qbuf, "ip6.arpa", sizeof(qbuf));
 615                 break;
 616         default:
 617                 abort();
 618         }
 619         if ((buf = malloc(sizeof(*buf))) == NULL) {
 620                 RES_SET_H_ERRNO(statp, NETDB_INTERNAL);
 621                 *h_errnop = statp->res_h_errno;
 622                 return NS_NOTFOUND;
 623         }
 624         n = res_nquery(statp, qbuf, C_IN, T_PTR, (u_char *)buf->buf,
 625             sizeof buf->buf);
 626         if (n < 0) {
 627                 free(buf);
 628                 dbg_printf("res_nquery failed (%d)\n", n, statp);
 629                 *h_errnop = statp->res_h_errno;
 630                 return (NS_UNAVAIL);
 631         }
 632         if (n > sizeof buf->buf) {
 633                 free(buf);
 634                 dbg_printf("static buffer is too small (%d)\n", n, statp);
 635                 *h_errnop = statp->res_h_errno;
 636                 return (NS_UNAVAIL);
 637         }
 638         if (gethostanswer(buf, n, qbuf, T_PTR, &he, hed, statp) != 0) {
 639                 free(buf);
 640                 *h_errnop = statp->res_h_errno;
 641                 switch (statp->res_h_errno) {
 642                 case HOST_NOT_FOUND:
 643                         return (NS_NOTFOUND);
 644                 case TRY_AGAIN:
 645                         return (NS_TRYAGAIN);
 646                 default:
 647                         return (NS_UNAVAIL);
 648                 }
 649                 /*NOTREACHED*/
 650         }
 651         free(buf);
 652 #ifdef SUNSECURITY
 653         if (af == AF_INET) {
 654             /*
 655              * turn off search as the name should be absolute,
 656              * 'localhost' should be matched by defnames
 657              */
 658             strncpy(hname2, he.h_name, MAXDNAME);
 659             hname2[MAXDNAME] = '\0';
 660             old_options = statp->options;
 661             statp->options &= ~RES_DNSRCH;
 662             statp->options |= RES_DEFNAMES;
 663             memset(&rhd, 0, sizeof rhd);
 664             rhe = gethostbyname_r(hname2, &rhd.host, &rhd.data,
 665                 sizeof(rhd.data), &ret_h_error);
 666             if (rhe == NULL) {
 667                 if (inet_ntop(af, addr, numaddr, sizeof(numaddr)) == NULL)
 668                     strlcpy(numaddr, "UNKNOWN", sizeof(numaddr));
 669                 syslog(LOG_NOTICE|LOG_AUTH,
 670                        "gethostbyaddr: No A record for %s (verifying [%s])",
 671                        hname2, numaddr);
 672                 statp->options = old_options;
 673                 RES_SET_H_ERRNO(statp, HOST_NOT_FOUND);
 674                 *h_errnop = statp->res_h_errno;
 675                 return (NS_NOTFOUND);
 676             }
 677             statp->options = old_options;
 678             for (haddr = rhe->h_addr_list; *haddr; haddr++)
 679                 if (!memcmp(*haddr, addr, NS_INADDRSZ))
 680                         break;
 681             if (!*haddr) {
 682                 if (inet_ntop(af, addr, numaddr, sizeof(numaddr)) == NULL)
 683                     strlcpy(numaddr, "UNKNOWN", sizeof(numaddr));
 684                 syslog(LOG_NOTICE|LOG_AUTH,
 685                        "gethostbyaddr: A record of %s != PTR record [%s]",
 686                        hname2, numaddr);
 687                 RES_SET_H_ERRNO(statp, HOST_NOT_FOUND);
 688                 *h_errnop = statp->res_h_errno;
 689                 return (NS_NOTFOUND);
 690             }
 691         }
 692 #endif /*SUNSECURITY*/
 693         he.h_addrtype = af;
 694         he.h_length = len;
 695         memcpy(hed->host_addr, uaddr, len);
 696         hed->h_addr_ptrs[0] = (char *)hed->host_addr;
 697         hed->h_addr_ptrs[1] = NULL;
 698         if (af == AF_INET && (statp->options & RES_USE_INET6)) {
 699                 _map_v4v6_address((char*)hed->host_addr, (char*)hed->host_addr);
 700                 he.h_addrtype = AF_INET6;
 701                 he.h_length = NS_IN6ADDRSZ;
 702         }
 703         if (__copy_hostent(&he, hptr, buffer, buflen) != 0) {
 704                 *errnop = errno;
 705                 RES_SET_H_ERRNO(statp, NETDB_INTERNAL);
 706                 *h_errnop = statp->res_h_errno;
 707                 return (NS_RETURN);
 708         }
 709         RES_SET_H_ERRNO(statp, NETDB_SUCCESS);
 710         *((struct hostent **)rval) = hptr;
 711         return (NS_SUCCESS);
 712 }
 713
 714 #ifdef RESOLVSORT
 715 static void
 716 addrsort(char **ap, int num, res_state res)
 717 {
 718         int i, j;
 719         char **p;
 720         short aval[_MAXADDRS];
 721         int needsort = 0;
 722
 723         p = ap;
 724         for (i = 0; i < num; i++, p++) {
 725             for (j = 0 ; (unsigned)j < res->nsort; j++)
 726                 if (res->sort_list[j].addr.s_addr ==
 727                     (((struct in_addr *)(*p))->s_addr & res->sort_list[j].mask))
 728                         break;
 729             aval[i] = j;
 730             if (needsort == 0 && i > 0 && j < aval[i-1])
 731                 needsort = i;
 732         }
 733         if (!needsort)
 734             return;
 735
 736         while (needsort < num) {
 737             for (j = needsort - 1; j >= 0; j--) {
 738                 if (aval[j] > aval[j+1]) {
 739                     char *hp;
 740
 741                     i = aval[j];
 742                     aval[j] = aval[j+1];
 743                     aval[j+1] = i;
 744
 745                     hp = ap[j];
 746                     ap[j] = ap[j+1];
 747                     ap[j+1] = hp;
 748
 749                 } else
 750                     break;
 751             }
 752             needsort++;
 753         }
 754 }
 755 #endif
 756
 757 void
 758 _sethostdnsent(int stayopen)
 759 {
 760         res_state statp;
 761
 762         statp = __res_state();
 763         if ((statp->options & RES_INIT) == 0 && res_ninit(statp) == -1)
 764                 return;
 765         if (stayopen)
 766                 statp->options |= RES_STAYOPEN | RES_USEVC;
 767 }
 768
 769 void
 770 _endhostdnsent(void)
 771 {
 772         res_state statp;
 773
 774         statp = __res_state();
 775         statp->options &= ~(RES_STAYOPEN | RES_USEVC);
 776         res_nclose(statp);
 777 }