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