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  * @(#)gethostnamadr.c  8.1 (Berkeley) 6/4/93
  52  * $From: Id: gethnamaddr.c,v 8.23 1998/04/07 04:59:46 vixie Exp $
  53  * $FreeBSD: src/lib/libc/net/gethostbydns.c,v 1.27.2.5 2002/11/02 18:54:57 ume Exp $
  54  * $DragonFly: src/lib/libc/net/gethostbydns.c,v 1.6 2005/11/13 02:04:47 swildner Exp $
  55  */
  56
  57 #include <sys/types.h>
  58 #include <sys/param.h>
  59 #include <sys/socket.h>
  60 #include <netinet/in.h>
  61 #include <arpa/inet.h>
  62 #include <arpa/nameser.h>
  63
  64 #include <stdio.h>
  65 #include <stdlib.h>
  66 #include <unistd.h>
  67 #include <string.h>
  68 #include <netdb.h>
  69 #include <resolv.h>
  70 #include <ctype.h>
  71 #include <errno.h>
  72 #include <syslog.h>
  73
  74 #include "res_config.h"
  75
  76 #define SPRINTF(x) ((size_t)sprintf x)
  77
  78 #define MAXALIASES      35
  79 #define MAXADDRS        35
  80
  81 static const char AskedForGot[] =
  82                 "gethostby*.gethostanswer: asked for \"%s\", got \"%s\"";
  83
  84 static char *h_addr_ptrs[MAXADDRS + 1];
  85
  86 static struct hostent host;
  87 static char *host_aliases[MAXALIASES];
  88 static char hostbuf[8*1024];
  89 static u_char host_addr[16];    /* IPv4 or IPv6 */
  90
  91 #ifdef RESOLVSORT
  92 static void addrsort (char **, int);
  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 extern int h_errno;
 108 int _dns_ttl_;
 109
 110 #ifdef DEBUG
 111 static void
 112 dprintf(char *msg, int num)
 113 {
 114         if (_res.options & RES_DEBUG) {
 115                 int save = errno;
 116
 117                 printf(msg, num);
 118                 errno = save;
 119         }
 120 }
 121 #else
 122 # define dprintf(msg, num) /*nada*/
 123 #endif
 124
 125 #define BOUNDED_INCR(x) \
 126         do { \
 127                 cp += x; \
 128                 if (cp > eom) { \
 129                         h_errno = NO_RECOVERY; \
 130                         return (NULL); \
 131                 } \
 132         } while (0)
 133
 134 #define BOUNDS_CHECK(ptr, count) \
 135         do { \
 136                 if ((ptr) + (count) > eom) { \
 137                         h_errno = NO_RECOVERY; \
 138                         return (NULL); \
 139                 } \
 140         } while (0)
 141
 142 static struct hostent *
 143 gethostanswer(const querybuf *answer, int anslen, const char *qname, int qtype)
 144 {
 145         const HEADER *hp;
 146         const u_char *cp;
 147         int n;
 148         const u_char *eom, *erdata;
 149         char *bp, **ap, **hap;
 150         int type, class, buflen, 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         host.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                 h_errno = NO_RECOVERY;
 170                 return (NULL);  /* 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 = hostbuf;
 179         buflen = sizeof hostbuf;
 180         cp = answer->buf;
 181         BOUNDED_INCR(HFIXEDSZ);
 182         if (qdcount != 1) {
 183                 h_errno = NO_RECOVERY;
 184                 return (NULL);
 185         }
 186         n = dn_expand(answer->buf, eom, cp, bp, buflen);
 187         if ((n < 0) || !(*name_ok)(bp)) {
 188                 h_errno = NO_RECOVERY;
 189                 return (NULL);
 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                         h_errno = NO_RECOVERY;
 200                         return (NULL);
 201                 }
 202                 host.h_name = bp;
 203                 bp += n;
 204                 buflen -= n;
 205                 /* The qname can be abbreviated, but h_name is now absolute. */
 206                 qname = host.h_name;
 207         }
 208         ap = host_aliases;
 209         *ap = NULL;
 210         host.h_aliases = host_aliases;
 211         hap = h_addr_ptrs;
 212         *hap = NULL;
 213         host.h_addr_list = h_addr_ptrs;
 214         haveanswer = 0;
 215         had_error = 0;
 216         _dns_ttl_ = -1;
 217         while (ancount-- > 0 && cp < eom && !had_error) {
 218                 n = dn_expand(answer->buf, eom, cp, bp, buflen);
 219                 if ((n < 0) || !(*name_ok)(bp)) {
 220                         had_error++;
 221                         continue;
 222                 }
 223                 cp += n;                        /* name */
 224                 BOUNDS_CHECK(cp, 3 * INT16SZ + INT32SZ);
 225                 type = _getshort(cp);
 226                 cp += INT16SZ;                  /* type */
 227                 class = _getshort(cp);
 228                 cp += INT16SZ;                  /* class */
 229                 if (qtype == T_A  && type == T_A)
 230                         _dns_ttl_ = _getlong(cp);
 231                 cp += INT32SZ;                  /* TTL */
 232                 n = _getshort(cp);
 233                 cp += INT16SZ;                  /* len */
 234                 BOUNDS_CHECK(cp, n);
 235                 erdata = cp + n;
 236                 if (class != C_IN) {
 237                         /* XXX - debug? syslog? */
 238                         cp += n;
 239                         continue;               /* XXX - had_error++ ? */
 240                 }
 241                 if ((qtype == T_A || qtype == T_AAAA) && type == T_CNAME) {
 242                         if (ap >= &host_aliases[MAXALIASES-1])
 243                                 continue;
 244                         n = dn_expand(answer->buf, eom, cp, tbuf, sizeof tbuf);
 245                         if ((n < 0) || !(*name_ok)(tbuf)) {
 246                                 had_error++;
 247                                 continue;
 248                         }
 249                         cp += n;
 250                         if (cp != erdata) {
 251                                 h_errno = NO_RECOVERY;
 252                                 return (NULL);
 253                         }
 254                         /* Store alias. */
 255                         *ap++ = bp;
 256                         n = strlen(bp) + 1;     /* for the \0 */
 257                         if (n >= MAXHOSTNAMELEN) {
 258                                 had_error++;
 259                                 continue;
 260                         }
 261                         bp += n;
 262                         buflen -= n;
 263                         /* Get canonical name. */
 264                         n = strlen(tbuf) + 1;   /* for the \0 */
 265                         if (n > buflen || n >= MAXHOSTNAMELEN) {
 266                                 had_error++;
 267                                 continue;
 268                         }
 269                         strcpy(bp, tbuf);
 270                         host.h_name = bp;
 271                         bp += n;
 272                         buflen -= n;
 273                         continue;
 274                 }
 275                 if (qtype == T_PTR && type == T_CNAME) {
 276                         n = dn_expand(answer->buf, eom, cp, tbuf, sizeof tbuf);
 277                         if (n < 0 || !res_dnok(tbuf)) {
 278                                 had_error++;
 279                                 continue;
 280                         }
 281                         cp += n;
 282                         if (cp != erdata) {
 283                                 h_errno = NO_RECOVERY;
 284                                 return (NULL);
 285                         }
 286                         /* Get canonical name. */
 287                         n = strlen(tbuf) + 1;   /* for the \0 */
 288                         if (n > buflen || n >= MAXHOSTNAMELEN) {
 289                                 had_error++;
 290                                 continue;
 291                         }
 292                         strcpy(bp, tbuf);
 293                         tname = bp;
 294                         bp += n;
 295                         buflen -= n;
 296                         continue;
 297                 }
 298                 if (type != qtype) {
 299                         if (type != T_SIG)
 300                                 syslog(LOG_NOTICE|LOG_AUTH,
 301         "gethostby*.gethostanswer: asked for \"%s %s %s\", got type \"%s\"",
 302                                        qname, p_class(C_IN), p_type(qtype),
 303                                        p_type(type));
 304                         cp += n;
 305                         continue;               /* XXX - had_error++ ? */
 306                 }
 307                 switch (type) {
 308                 case T_PTR:
 309                         if (strcasecmp(tname, bp) != 0) {
 310                                 syslog(LOG_NOTICE|LOG_AUTH,
 311                                        AskedForGot, qname, bp);
 312                                 cp += n;
 313                                 continue;       /* XXX - had_error++ ? */
 314                         }
 315                         n = dn_expand(answer->buf, eom, cp, bp, buflen);
 316                         if ((n < 0) || !res_hnok(bp)) {
 317                                 had_error++;
 318                                 break;
 319                         }
 320 #if MULTI_PTRS_ARE_ALIASES
 321                         cp += n;
 322                         if (cp != erdata) {
 323                                 h_errno = NO_RECOVERY;
 324                                 return (NULL);
 325                         }
 326                         if (!haveanswer)
 327                                 host.h_name = bp;
 328                         else if (ap < &host_aliases[MAXALIASES-1])
 329                                 *ap++ = bp;
 330                         else
 331                                 n = -1;
 332                         if (n != -1) {
 333                                 n = strlen(bp) + 1;     /* for the \0 */
 334                                 if (n >= MAXHOSTNAMELEN) {
 335                                         had_error++;
 336                                         break;
 337                                 }
 338                                 bp += n;
 339                                 buflen -= n;
 340                         }
 341                         break;
 342 #else
 343                         host.h_name = bp;
 344                         if (_res.options & RES_USE_INET6) {
 345                                 n = strlen(bp) + 1;     /* for the \0 */
 346                                 if (n >= MAXHOSTNAMELEN) {
 347                                         had_error++;
 348                                         break;
 349                                 }
 350                                 bp += n;
 351                                 buflen -= n;
 352                                 _map_v4v6_hostent(&host, &bp, &buflen);
 353                         }
 354                         h_errno = NETDB_SUCCESS;
 355                         return (&host);
 356 #endif
 357                 case T_A:
 358                 case T_AAAA:
 359                         if (strcasecmp(host.h_name, bp) != 0) {
 360                                 syslog(LOG_NOTICE|LOG_AUTH,
 361                                        AskedForGot, host.h_name, bp);
 362                                 cp += n;
 363                                 continue;       /* XXX - had_error++ ? */
 364                         }
 365                         if (n != host.h_length) {
 366                                 cp += n;
 367                                 continue;
 368                         }
 369                         if (!haveanswer) {
 370                                 int nn;
 371
 372                                 host.h_name = bp;
 373                                 nn = strlen(bp) + 1;    /* for the \0 */
 374                                 bp += nn;
 375                                 buflen -= nn;
 376                         }
 377
 378                         buflen -= sizeof(align) - ((u_long)bp % sizeof(align));
 379                         bp += sizeof(align) - ((u_long)bp % sizeof(align));
 380
 381                         if (bp + n >= &hostbuf[sizeof hostbuf]) {
 382                                 dprintf("size (%d) too big\n", n);
 383                                 had_error++;
 384                                 continue;
 385                         }
 386                         if (hap >= &h_addr_ptrs[MAXADDRS-1]) {
 387                                 if (!toobig++)
 388                                         dprintf("Too many addresses (%d)\n",
 389                                                 MAXADDRS);
 390                                 cp += n;
 391                                 continue;
 392                         }
 393                         bcopy(cp, *hap++ = bp, n);
 394                         bp += n;
 395                         buflen -= n;
 396                         cp += n;
 397                         if (cp != erdata) {
 398                                 h_errno = NO_RECOVERY;
 399                                 return (NULL);
 400                         }
 401                         break;
 402                 default:
 403                         dprintf("Impossible condition (type=%d)\n", type);
 404                         h_errno = NO_RECOVERY;
 405                         return (NULL);
 406                         /* BIND has abort() here, too risky on bad data */
 407                 }
 408                 if (!had_error)
 409                         haveanswer++;
 410         }
 411         if (haveanswer) {
 412                 *ap = NULL;
 413                 *hap = NULL;
 414 # if defined(RESOLVSORT)
 415                 /*
 416                  * Note: we sort even if host can take only one address
 417                  * in its return structures - should give it the "best"
 418                  * address in that case, not some random one
 419                  */
 420                 if (_res.nsort && haveanswer > 1 && qtype == T_A)
 421                         addrsort(h_addr_ptrs, haveanswer);
 422 # endif /*RESOLVSORT*/
 423                 if (!host.h_name) {
 424                         n = strlen(qname) + 1;  /* for the \0 */
 425                         if (n > buflen || n >= MAXHOSTNAMELEN)
 426                                 goto no_recovery;
 427                         strcpy(bp, qname);
 428                         host.h_name = bp;
 429                         bp += n;
 430                         buflen -= n;
 431                 }
 432                 if (_res.options & RES_USE_INET6)
 433                         _map_v4v6_hostent(&host, &bp, &buflen);
 434                 h_errno = NETDB_SUCCESS;
 435                 return (&host);
 436         }
 437  no_recovery:
 438         h_errno = NO_RECOVERY;
 439         return (NULL);
 440 }
 441
 442 struct hostent *
 443 __dns_getanswer(const char *answer, int anslen, const char *qname, int qtype)
 444 {
 445         switch(qtype) {
 446         case T_AAAA:
 447                 host.h_addrtype = AF_INET6;
 448                 host.h_length = IN6ADDRSZ;
 449                 break;
 450         case T_A:
 451         default:
 452                 host.h_addrtype = AF_INET;
 453                 host.h_length = INADDRSZ;
 454                 break;
 455         }
 456
 457         return(gethostanswer((const querybuf *)answer, anslen, qname, qtype));
 458 }
 459
 460 struct hostent *
 461 _gethostbydnsname(const char *name, int af)
 462 {
 463         querybuf *buf;
 464         const char *cp;
 465         char *bp;
 466         int n, size, type, len;
 467         struct hostent *hp;
 468
 469         if ((_res.options & RES_INIT) == 0 && res_init() == -1) {
 470                 h_errno = NETDB_INTERNAL;
 471                 return (NULL);
 472         }
 473
 474         switch (af) {
 475         case AF_INET:
 476                 size = INADDRSZ;
 477                 type = T_A;
 478                 break;
 479         case AF_INET6:
 480                 size = IN6ADDRSZ;
 481                 type = T_AAAA;
 482                 break;
 483         default:
 484                 h_errno = NETDB_INTERNAL;
 485                 errno = EAFNOSUPPORT;
 486                 return (NULL);
 487         }
 488
 489         host.h_addrtype = af;
 490         host.h_length = size;
 491
 492         /*
 493          * if there aren't any dots, it could be a user-level alias.
 494          * this is also done in res_query() since we are not the only
 495          * function that looks up host names.
 496          */
 497         if (!strchr(name, '.') && (cp = __hostalias(name)))
 498                 name = cp;
 499
 500         /*
 501          * disallow names consisting only of digits/dots, unless
 502          * they end in a dot.
 503          */
 504         if (isdigit((unsigned char)name[0]))
 505                 for (cp = name;; ++cp) {
 506                         if (!*cp) {
 507                                 if (*--cp == '.')
 508                                         break;
 509                                 /*
 510                                  * All-numeric, no dot at the end.
 511                                  * Fake up a hostent as if we'd actually
 512                                  * done a lookup.
 513                                  */
 514                                 if (inet_pton(af, name, host_addr) <= 0) {
 515                                         h_errno = HOST_NOT_FOUND;
 516                                         return (NULL);
 517                                 }
 518                                 strncpy(hostbuf, name, MAXDNAME);
 519                                 hostbuf[MAXDNAME] = '\0';
 520                                 bp = hostbuf + MAXDNAME;
 521                                 len = sizeof hostbuf - MAXDNAME;
 522                                 host.h_name = hostbuf;
 523                                 host.h_aliases = host_aliases;
 524                                 host_aliases[0] = NULL;
 525                                 h_addr_ptrs[0] = (char *)host_addr;
 526                                 h_addr_ptrs[1] = NULL;
 527                                 host.h_addr_list = h_addr_ptrs;
 528                                 if (_res.options & RES_USE_INET6)
 529                                         _map_v4v6_hostent(&host, &bp, &len);
 530                                 h_errno = NETDB_SUCCESS;
 531                                 return (&host);
 532                         }
 533                         if (!isdigit((unsigned char)*cp) && *cp != '.')
 534                                 break;
 535                 }
 536         if ((isxdigit((unsigned char)name[0]) && strchr(name, ':') != NULL) ||
 537             name[0] == ':')
 538                 for (cp = name;; ++cp) {
 539                         if (!*cp) {
 540                                 if (*--cp == '.')
 541                                         break;
 542                                 /*
 543                                  * All-IPv6-legal, no dot at the end.
 544                                  * Fake up a hostent as if we'd actually
 545                                  * done a lookup.
 546                                  */
 547                                 if (inet_pton(af, name, host_addr) <= 0) {
 548                                         h_errno = HOST_NOT_FOUND;
 549                                         return (NULL);
 550                                 }
 551                                 strncpy(hostbuf, name, MAXDNAME);
 552                                 hostbuf[MAXDNAME] = '\0';
 553                                 bp = hostbuf + MAXDNAME;
 554                                 len = sizeof hostbuf - MAXDNAME;
 555                                 host.h_name = hostbuf;
 556                                 host.h_aliases = host_aliases;
 557                                 host_aliases[0] = NULL;
 558                                 h_addr_ptrs[0] = (char *)host_addr;
 559                                 h_addr_ptrs[1] = NULL;
 560                                 host.h_addr_list = h_addr_ptrs;
 561                                 h_errno = NETDB_SUCCESS;
 562                                 return (&host);
 563                         }
 564                         if (!isxdigit((unsigned char)*cp) && *cp != ':' && *cp != '.')
 565                                 break;
 566                 }
 567
 568         if ((buf = malloc(sizeof(*buf))) == NULL) {
 569                 h_errno = NETDB_INTERNAL;
 570                 return (NULL);
 571         }
 572         n = res_search(name, C_IN, type, buf->buf, sizeof(buf->buf));
 573         if (n < 0) {
 574                 free(buf);
 575                 dprintf("res_search failed (%d)\n", n);
 576                 return (NULL);
 577         } else if (n > sizeof(buf->buf)) {
 578                 free(buf);
 579                 dprintf("static buffer is too small (%d)\n", n);
 580                 return (NULL);
 581         }
 582         hp = gethostanswer(buf, n, name, type);
 583         free(buf);
 584         return (hp);
 585 }
 586
 587 struct hostent *
 588 _gethostbydnsaddr(const char *addr,     /* XXX should have been def'd as u_char! */
 589                   int len,
 590                   int af)
 591 {
 592         const u_char *uaddr = (const u_char *)addr;
 593         static const u_char mapped[] = { 0,0, 0,0, 0,0, 0,0, 0,0, 0xff,0xff };
 594         static const u_char tunnelled[] = { 0,0, 0,0, 0,0, 0,0, 0,0, 0,0 };
 595         int n, size;
 596         querybuf *buf;
 597         struct hostent *hp;
 598         char qbuf[MAXDNAME+1], *qp;
 599 #ifdef SUNSECURITY
 600         struct hostent *rhp;
 601         char **haddr;
 602         u_long old_options;
 603         char hname2[MAXDNAME+1];
 604 #endif /*SUNSECURITY*/
 605
 606         if ((_res.options & RES_INIT) == 0 && res_init() == -1) {
 607                 h_errno = NETDB_INTERNAL;
 608                 return (NULL);
 609         }
 610         if (af == AF_INET6 && len == IN6ADDRSZ &&
 611             (!bcmp(uaddr, mapped, sizeof mapped) ||
 612              !bcmp(uaddr, tunnelled, sizeof tunnelled))) {
 613                 /* Unmap. */
 614                 addr += sizeof mapped;
 615                 uaddr += sizeof mapped;
 616                 af = AF_INET;
 617                 len = INADDRSZ;
 618         }
 619         switch (af) {
 620         case AF_INET:
 621                 size = INADDRSZ;
 622                 break;
 623         case AF_INET6:
 624                 size = IN6ADDRSZ;
 625                 break;
 626         default:
 627                 errno = EAFNOSUPPORT;
 628                 h_errno = NETDB_INTERNAL;
 629                 return (NULL);
 630         }
 631         if (size != len) {
 632                 errno = EINVAL;
 633                 h_errno = NETDB_INTERNAL;
 634                 return (NULL);
 635         }
 636         switch (af) {
 637         case AF_INET:
 638                 sprintf(qbuf, "%u.%u.%u.%u.in-addr.arpa",
 639                                (uaddr[3] & 0xff),
 640                                (uaddr[2] & 0xff),
 641                                (uaddr[1] & 0xff),
 642                                (uaddr[0] & 0xff));
 643                 break;
 644         case AF_INET6:
 645                 qp = qbuf;
 646                 for (n = IN6ADDRSZ - 1; n >= 0; n--) {
 647                         qp += SPRINTF((qp, "%x.%x.",
 648                                        uaddr[n] & 0xf,
 649                                        (uaddr[n] >> 4) & 0xf));
 650                 }
 651                 strlcat(qbuf, "ip6.arpa", sizeof(qbuf));
 652                 break;
 653         default:
 654                 abort();
 655         }
 656         if ((buf = malloc(sizeof(*buf))) == NULL) {
 657                 h_errno = NETDB_INTERNAL;
 658                 return (NULL);
 659         }
 660         n = res_query(qbuf, C_IN, T_PTR, (u_char *)buf->buf, sizeof buf->buf);
 661         if (n < 0 && af == AF_INET6) {
 662                 *qp = '\0';
 663                 strlcat(qbuf, "ip6.int", sizeof(qbuf));
 664                 n = res_query(qbuf, C_IN, T_PTR, (u_char *)buf->buf,
 665                               sizeof buf->buf);
 666         }
 667         if (n < 0) {
 668                 free(buf);
 669                 dprintf("res_query failed (%d)\n", n);
 670                 return (NULL);
 671         }
 672         if (n > sizeof buf->buf) {
 673                 free(buf);
 674                 dprintf("static buffer is too small (%d)\n", n);
 675                 return (NULL);
 676         }
 677         if (!(hp = gethostanswer(buf, n, qbuf, T_PTR))) {
 678                 free(buf);
 679                 return (NULL);  /* h_errno was set by gethostanswer() */
 680         }
 681         free(buf);
 682 #ifdef SUNSECURITY
 683         if (af == AF_INET) {
 684             /*
 685              * turn off search as the name should be absolute,
 686              * 'localhost' should be matched by defnames
 687              */
 688             strncpy(hname2, hp->h_name, MAXDNAME);
 689             hname2[MAXDNAME] = '\0';
 690             old_options = _res.options;
 691             _res.options &= ~RES_DNSRCH;
 692             _res.options |= RES_DEFNAMES;
 693             if (!(rhp = gethostbyname(hname2))) {
 694                 syslog(LOG_NOTICE|LOG_AUTH,
 695                        "gethostbyaddr: No A record for %s (verifying [%s])",
 696                        hname2, inet_ntoa(*((struct in_addr *)addr)));
 697                 _res.options = old_options;
 698                 h_errno = HOST_NOT_FOUND;
 699                 return (NULL);
 700             }
 701             _res.options = old_options;
 702             for (haddr = rhp->h_addr_list; *haddr; haddr++)
 703                 if (!memcmp(*haddr, addr, INADDRSZ))
 704                         break;
 705             if (!*haddr) {
 706                 syslog(LOG_NOTICE|LOG_AUTH,
 707                        "gethostbyaddr: A record of %s != PTR record [%s]",
 708                        hname2, inet_ntoa(*((struct in_addr *)addr)));
 709                 h_errno = HOST_NOT_FOUND;
 710                 return (NULL);
 711             }
 712         }
 713 #endif /*SUNSECURITY*/
 714         hp->h_addrtype = af;
 715         hp->h_length = len;
 716         bcopy(addr, host_addr, len);
 717         h_addr_ptrs[0] = (char *)host_addr;
 718         h_addr_ptrs[1] = NULL;
 719         if (af == AF_INET && (_res.options & RES_USE_INET6)) {
 720                 _map_v4v6_address((char*)host_addr, (char*)host_addr);
 721                 hp->h_addrtype = AF_INET6;
 722                 hp->h_length = IN6ADDRSZ;
 723         }
 724         h_errno = NETDB_SUCCESS;
 725         return (hp);
 726 }
 727
 728 #ifdef RESOLVSORT
 729 static void
 730 addrsort(char **ap, int num)
 731 {
 732         int i, j;
 733         char **p;
 734         short aval[MAXADDRS];
 735         int needsort = 0;
 736
 737         p = ap;
 738         for (i = 0; i < num; i++, p++) {
 739             for (j = 0 ; (unsigned)j < _res.nsort; j++)
 740                 if (_res.sort_list[j].addr.s_addr ==
 741                     (((struct in_addr *)(*p))->s_addr & _res.sort_list[j].mask))
 742                         break;
 743             aval[i] = j;
 744             if (needsort == 0 && i > 0 && j < aval[i-1])
 745                 needsort = i;
 746         }
 747         if (!needsort)
 748             return;
 749
 750         while (needsort < num) {
 751             for (j = needsort - 1; j >= 0; j--) {
 752                 if (aval[j] > aval[j+1]) {
 753                     char *hp;
 754
 755                     i = aval[j];
 756                     aval[j] = aval[j+1];
 757                     aval[j+1] = i;
 758
 759                     hp = ap[j];
 760                     ap[j] = ap[j+1];
 761                     ap[j+1] = hp;
 762
 763                 } else
 764                     break;
 765             }
 766             needsort++;
 767         }
 768 }
 769 #endif
 770 void
 771 _sethostdnsent(int stayopen)
 772 {
 773         if ((_res.options & RES_INIT) == 0 && res_init() == -1)
 774                 return;
 775         if (stayopen)
 776                 _res.options |= RES_STAYOPEN | RES_USEVC;
 777 }
 778
 779 void
 780 _endhostdnsent(void)
 781 {
 782         _res.options &= ~(RES_STAYOPEN | RES_USEVC);
 783         res_close();
 784 }