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. All advertising materials mentioning features or use of this software
  16  *    must display the following acknowledgement:
  17  *      This product includes software developed by the University of
  18  *      California, Berkeley and its contributors.
  19  * 4. Neither the name of the University nor the names of its contributors
  20  *    may be used to endorse or promote products derived from this software
  21  *    without specific prior written permission.
  22  *
  23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  33  * SUCH DAMAGE.
  34  * -
  35  * Portions Copyright (c) 1993 by Digital Equipment Corporation.
  36  *
  37  * Permission to use, copy, modify, and distribute this software for any
  38  * purpose with or without fee is hereby granted, provided that the above
  39  * copyright notice and this permission notice appear in all copies, and that
  40  * the name of Digital Equipment Corporation not be used in advertising or
  41  * publicity pertaining to distribution of the document or software without
  42  * specific, written prior permission.
  43  *
  44  * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
  45  * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
  46  * OF MERCHANTABILITY AND FITNESS.   IN NO EVENT SHALL DIGITAL EQUIPMENT
  47  * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
  48  * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
  49  * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
  50  * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
  51  * SOFTWARE.
  52  * -
  53  * --Copyright--
  54  */
  55
  56 #if defined(LIBC_SCCS) && !defined(lint)
  57 static char sccsid[] = "@(#)gethostnamadr.c     8.1 (Berkeley) 6/4/93";
  58 static char fromrcsid[] = "From: Id: gethnamaddr.c,v 8.23 1998/04/07 04:59:46 vixie Exp $";
  59 #endif /* LIBC_SCCS and not lint */
  60 #include <sys/cdefs.h>
  61 __FBSDID("$FreeBSD$");
  62
  63 #include <sys/types.h>
  64 #include <sys/param.h>
  65 #include <sys/socket.h>
  66 #include <netinet/in.h>
  67 #include <arpa/inet.h>
  68 #include <arpa/nameser.h>
  69
  70 #include <stdio.h>
  71 #include <unistd.h>
  72 #include <string.h>
  73 #include <netdb.h>
  74 #include <resolv.h>
  75 #include <ctype.h>
  76 #include <errno.h>
  77 #include <syslog.h>
  78 #include <stdarg.h>
  79 #include <nsswitch.h>
  80
  81 #include "res_config.h"
  82
  83 #define SPRINTF(x) ((size_t)sprintf x)
  84
  85 #define MAXALIASES      35
  86 #define MAXADDRS        35
  87
  88 static const char AskedForGot[] =
  89                 "gethostby*.gethostanswer: asked for \"%s\", got \"%s\"";
  90
  91 static char *h_addr_ptrs[MAXADDRS + 1];
  92
  93 static struct hostent host;
  94 static char *host_aliases[MAXALIASES];
  95 static char hostbuf[8*1024];
  96 static u_char host_addr[16];    /* IPv4 or IPv6 */
  97
  98 #ifdef RESOLVSORT
  99 static void addrsort(char **, int);
 100 #endif
 101
 102 #ifdef DEBUG
 103 static void dprintf(char *, int) __printflike(1, 0);
 104 #endif
 105
 106 #if PACKETSZ > 1024
 107 #define MAXPACKET       PACKETSZ
 108 #else
 109 #define MAXPACKET       1024
 110 #endif
 111
 112 typedef union {
 113     HEADER hdr;
 114     u_char buf[MAXPACKET];
 115 } querybuf;
 116
 117 typedef union {
 118     int32_t al;
 119     char ac;
 120 } align;
 121
 122 extern int h_errno;
 123 int _dns_ttl_;
 124
 125 #ifdef DEBUG
 126 static void
 127 dprintf(msg, num)
 128         char *msg;
 129         int num;
 130 {
 131         if (_res.options & RES_DEBUG) {
 132                 int save = errno;
 133
 134                 printf(msg, num);
 135                 errno = save;
 136         }
 137 }
 138 #else
 139 # define dprintf(msg, num) /*nada*/
 140 #endif
 141
 142 #define BOUNDED_INCR(x) \
 143         do { \
 144                 cp += x; \
 145                 if (cp > eom) { \
 146                         h_errno = NO_RECOVERY; \
 147                         return (NULL); \
 148                 } \
 149         } while (0)
 150
 151 #define BOUNDS_CHECK(ptr, count) \
 152         do { \
 153                 if ((ptr) + (count) > eom) { \
 154                         h_errno = NO_RECOVERY; \
 155                         return (NULL); \
 156                 } \
 157         } while (0)
 158
 159 static struct hostent *
 160 gethostanswer(answer, anslen, qname, qtype)
 161         const querybuf *answer;
 162         int anslen;
 163         const char *qname;
 164         int qtype;
 165 {
 166         const HEADER *hp;
 167         const u_char *cp;
 168         int n;
 169         const u_char *eom, *erdata;
 170         char *bp, *ep, **ap, **hap;
 171         int type, class, ancount, qdcount;
 172         int haveanswer, had_error;
 173         int toobig = 0;
 174         char tbuf[MAXDNAME];
 175         const char *tname;
 176         int (*name_ok)(const char *);
 177
 178         tname = qname;
 179         host.h_name = NULL;
 180         eom = answer->buf + anslen;
 181         switch (qtype) {
 182         case T_A:
 183         case T_AAAA:
 184                 name_ok = res_hnok;
 185                 break;
 186         case T_PTR:
 187                 name_ok = res_dnok;
 188                 break;
 189         default:
 190                 h_errno = NO_RECOVERY;
 191                 return (NULL);  /* XXX should be abort(); */
 192         }
 193         /*
 194          * find first satisfactory answer
 195          */
 196         hp = &answer->hdr;
 197         ancount = ntohs(hp->ancount);
 198         qdcount = ntohs(hp->qdcount);
 199         bp = hostbuf;
 200         ep = hostbuf + sizeof hostbuf;
 201         cp = answer->buf;
 202         BOUNDED_INCR(HFIXEDSZ);
 203         if (qdcount != 1) {
 204                 h_errno = NO_RECOVERY;
 205                 return (NULL);
 206         }
 207         n = dn_expand(answer->buf, eom, cp, bp, ep - bp);
 208         if ((n < 0) || !(*name_ok)(bp)) {
 209                 h_errno = NO_RECOVERY;
 210                 return (NULL);
 211         }
 212         BOUNDED_INCR(n + QFIXEDSZ);
 213         if (qtype == T_A || qtype == T_AAAA) {
 214                 /* res_send() has already verified that the query name is the
 215                  * same as the one we sent; this just gets the expanded name
 216                  * (i.e., with the succeeding search-domain tacked on).
 217                  */
 218                 n = strlen(bp) + 1;             /* for the \0 */
 219                 if (n >= MAXHOSTNAMELEN) {
 220                         h_errno = NO_RECOVERY;
 221                         return (NULL);
 222                 }
 223                 host.h_name = bp;
 224                 bp += n;
 225                 /* The qname can be abbreviated, but h_name is now absolute. */
 226                 qname = host.h_name;
 227         }
 228         ap = host_aliases;
 229         *ap = NULL;
 230         host.h_aliases = host_aliases;
 231         hap = h_addr_ptrs;
 232         *hap = NULL;
 233         host.h_addr_list = h_addr_ptrs;
 234         haveanswer = 0;
 235         had_error = 0;
 236         _dns_ttl_ = -1;
 237         while (ancount-- > 0 && cp < eom && !had_error) {
 238                 n = dn_expand(answer->buf, eom, cp, bp, ep - bp);
 239                 if ((n < 0) || !(*name_ok)(bp)) {
 240                         had_error++;
 241                         continue;
 242                 }
 243                 cp += n;                        /* name */
 244                 BOUNDS_CHECK(cp, 3 * INT16SZ + INT32SZ);
 245                 type = _getshort(cp);
 246                 cp += INT16SZ;                  /* type */
 247                 class = _getshort(cp);
 248                 cp += INT16SZ;                  /* class */
 249                 if (qtype == T_A  && type == T_A)
 250                         _dns_ttl_ = _getlong(cp);
 251                 cp += INT32SZ;                  /* TTL */
 252                 n = _getshort(cp);
 253                 cp += INT16SZ;                  /* len */
 254                 BOUNDS_CHECK(cp, n);
 255                 erdata = cp + n;
 256                 if (class != C_IN) {
 257                         /* XXX - debug? syslog? */
 258                         cp += n;
 259                         continue;               /* XXX - had_error++ ? */
 260                 }
 261                 if ((qtype == T_A || qtype == T_AAAA) && type == T_CNAME) {
 262                         if (ap >= &host_aliases[MAXALIASES-1])
 263                                 continue;
 264                         n = dn_expand(answer->buf, eom, cp, tbuf, sizeof tbuf);
 265                         if ((n < 0) || !(*name_ok)(tbuf)) {
 266                                 had_error++;
 267                                 continue;
 268                         }
 269                         cp += n;
 270                         if (cp != erdata) {
 271                                 h_errno = NO_RECOVERY;
 272                                 return (NULL);
 273                         }
 274                         /* Store alias. */
 275                         *ap++ = bp;
 276                         n = strlen(bp) + 1;     /* for the \0 */
 277                         if (n >= MAXHOSTNAMELEN) {
 278                                 had_error++;
 279                                 continue;
 280                         }
 281                         bp += n;
 282                         /* Get canonical name. */
 283                         n = strlen(tbuf) + 1;   /* for the \0 */
 284                         if (n > ep - bp || n >= MAXHOSTNAMELEN) {
 285                                 had_error++;
 286                                 continue;
 287                         }
 288                         strcpy(bp, tbuf);
 289                         host.h_name = bp;
 290                         bp += n;
 291                         continue;
 292                 }
 293                 if (qtype == T_PTR && type == T_CNAME) {
 294                         n = dn_expand(answer->buf, eom, cp, tbuf, sizeof tbuf);
 295                         if (n < 0 || !res_dnok(tbuf)) {
 296                                 had_error++;
 297                                 continue;
 298                         }
 299                         cp += n;
 300                         if (cp != erdata) {
 301                                 h_errno = NO_RECOVERY;
 302                                 return (NULL);
 303                         }
 304                         /* Get canonical name. */
 305                         n = strlen(tbuf) + 1;   /* for the \0 */
 306                         if (n > ep - bp || n >= MAXHOSTNAMELEN) {
 307                                 had_error++;
 308                                 continue;
 309                         }
 310                         strcpy(bp, tbuf);
 311                         tname = bp;
 312                         bp += n;
 313                         continue;
 314                 }
 315                 if (type != qtype) {
 316                         if (type != T_SIG)
 317                                 syslog(LOG_NOTICE|LOG_AUTH,
 318         "gethostby*.gethostanswer: asked for \"%s %s %s\", got type \"%s\"",
 319                                        qname, p_class(C_IN), p_type(qtype),
 320                                        p_type(type));
 321                         cp += n;
 322                         continue;               /* XXX - had_error++ ? */
 323                 }
 324                 switch (type) {
 325                 case T_PTR:
 326                         if (strcasecmp(tname, bp) != 0) {
 327                                 syslog(LOG_NOTICE|LOG_AUTH,
 328                                        AskedForGot, qname, bp);
 329                                 cp += n;
 330                                 continue;       /* XXX - had_error++ ? */
 331                         }
 332                         n = dn_expand(answer->buf, eom, cp, bp, ep - bp);
 333                         if ((n < 0) || !res_hnok(bp)) {
 334                                 had_error++;
 335                                 break;
 336                         }
 337 #if MULTI_PTRS_ARE_ALIASES
 338                         cp += n;
 339                         if (cp != erdata) {
 340                                 h_errno = NO_RECOVERY;
 341                                 return (NULL);
 342                         }
 343                         if (!haveanswer)
 344                                 host.h_name = bp;
 345                         else if (ap < &host_aliases[MAXALIASES-1])
 346                                 *ap++ = bp;
 347                         else
 348                                 n = -1;
 349                         if (n != -1) {
 350                                 n = strlen(bp) + 1;     /* for the \0 */
 351                                 if (n >= MAXHOSTNAMELEN) {
 352                                         had_error++;
 353                                         break;
 354                                 }
 355                                 bp += n;
 356                         }
 357                         break;
 358 #else
 359                         host.h_name = bp;
 360                         if (_res.options & RES_USE_INET6) {
 361                                 n = strlen(bp) + 1;     /* for the \0 */
 362                                 if (n >= MAXHOSTNAMELEN) {
 363                                         had_error++;
 364                                         break;
 365                                 }
 366                                 bp += n;
 367                                 _map_v4v6_hostent(&host, &bp, &ep);
 368                         }
 369                         h_errno = NETDB_SUCCESS;
 370                         return (&host);
 371 #endif
 372                 case T_A:
 373                 case T_AAAA:
 374                         if (strcasecmp(host.h_name, bp) != 0) {
 375                                 syslog(LOG_NOTICE|LOG_AUTH,
 376                                        AskedForGot, host.h_name, bp);
 377                                 cp += n;
 378                                 continue;       /* XXX - had_error++ ? */
 379                         }
 380                         if (n != host.h_length) {
 381                                 cp += n;
 382                                 continue;
 383                         }
 384                         if (!haveanswer) {
 385                                 int nn;
 386
 387                                 host.h_name = bp;
 388                                 nn = strlen(bp) + 1;    /* for the \0 */
 389                                 bp += nn;
 390                         }
 391
 392                         bp += sizeof(align) - ((u_long)bp % sizeof(align));
 393
 394                         if (bp + n >= ep) {
 395                                 dprintf("size (%d) too big\n", n);
 396                                 had_error++;
 397                                 continue;
 398                         }
 399                         if (hap >= &h_addr_ptrs[MAXADDRS-1]) {
 400                                 if (!toobig++)
 401                                         dprintf("Too many addresses (%d)\n",
 402                                                 MAXADDRS);
 403                                 cp += n;
 404                                 continue;
 405                         }
 406                         bcopy(cp, *hap++ = bp, n);
 407                         bp += n;
 408                         cp += n;
 409                         if (cp != erdata) {
 410                                 h_errno = NO_RECOVERY;
 411                                 return (NULL);
 412                         }
 413                         break;
 414                 default:
 415                         dprintf("Impossible condition (type=%d)\n", type);
 416                         h_errno = NO_RECOVERY;
 417                         return (NULL);
 418                         /* BIND has abort() here, too risky on bad data */
 419                 }
 420                 if (!had_error)
 421                         haveanswer++;
 422         }
 423         if (haveanswer) {
 424                 *ap = NULL;
 425                 *hap = NULL;
 426 # if defined(RESOLVSORT)
 427                 /*
 428                  * Note: we sort even if host can take only one address
 429                  * in its return structures - should give it the "best"
 430                  * address in that case, not some random one
 431                  */
 432                 if (_res.nsort && haveanswer > 1 && qtype == T_A)
 433                         addrsort(h_addr_ptrs, haveanswer);
 434 # endif /*RESOLVSORT*/
 435                 if (!host.h_name) {
 436                         n = strlen(qname) + 1;  /* for the \0 */
 437                         if (n > ep - bp || n >= MAXHOSTNAMELEN)
 438                                 goto no_recovery;
 439                         strcpy(bp, qname);
 440                         host.h_name = bp;
 441                         bp += n;
 442                 }
 443                 if (_res.options & RES_USE_INET6)
 444                         _map_v4v6_hostent(&host, &bp, &ep);
 445                 h_errno = NETDB_SUCCESS;
 446                 return (&host);
 447         }
 448  no_recovery:
 449         h_errno = NO_RECOVERY;
 450         return (NULL);
 451 }
 452
 453 struct hostent *
 454 __dns_getanswer(answer, anslen, qname, qtype)
 455         const char *answer;
 456         int anslen;
 457         const char *qname;
 458         int qtype;
 459 {
 460         switch(qtype) {
 461         case T_AAAA:
 462                 host.h_addrtype = AF_INET6;
 463                 host.h_length = IN6ADDRSZ;
 464                 break;
 465         case T_A:
 466         default:
 467                 host.h_addrtype = AF_INET;
 468                 host.h_length = INADDRSZ;
 469                 break;
 470         }
 471
 472         return(gethostanswer((const querybuf *)answer, anslen, qname, qtype));
 473 }
 474
 475 int
 476 _dns_gethostbyname(void *rval, void *cb_data, va_list ap)
 477 {
 478         const char *name;
 479         int af;
 480         querybuf buf;
 481         const char *cp;
 482         char *bp, *ep;
 483         int n, size, type, len;
 484
 485         name = va_arg(ap, const char *);
 486         af = va_arg(ap, int);
 487         *(struct hostent **)rval = NULL;
 488
 489         if ((_res.options & RES_INIT) == 0 && res_init() == -1) {
 490                 h_errno = NETDB_INTERNAL;
 491                 return NS_UNAVAIL;
 492         }
 493
 494         switch (af) {
 495         case AF_INET:
 496                 size = INADDRSZ;
 497                 type = T_A;
 498                 break;
 499         case AF_INET6:
 500                 size = IN6ADDRSZ;
 501                 type = T_AAAA;
 502                 break;
 503         default:
 504                 h_errno = NETDB_INTERNAL;
 505                 errno = EAFNOSUPPORT;
 506                 return NS_UNAVAIL;
 507         }
 508
 509         host.h_addrtype = af;
 510         host.h_length = size;
 511
 512         /*
 513          * if there aren't any dots, it could be a user-level alias.
 514          * this is also done in res_query() since we are not the only
 515          * function that looks up host names.
 516          */
 517         if (!strchr(name, '.') && (cp = __hostalias(name)))
 518                 name = cp;
 519
 520         /*
 521          * disallow names consisting only of digits/dots, unless
 522          * they end in a dot.
 523          */
 524         if (isdigit((unsigned char)name[0]))
 525                 for (cp = name;; ++cp) {
 526                         if (!*cp) {
 527                                 if (*--cp == '.')
 528                                         break;
 529                                 /*
 530                                  * All-numeric, no dot at the end.
 531                                  * Fake up a hostent as if we'd actually
 532                                  * done a lookup.
 533                                  */
 534                                 if (inet_pton(af, name, host_addr) <= 0) {
 535                                         h_errno = HOST_NOT_FOUND;
 536                                         return NS_NOTFOUND;
 537                                 }
 538                                 strncpy(hostbuf, name, MAXDNAME);
 539                                 hostbuf[MAXDNAME] = '\0';
 540                                 bp = hostbuf + MAXDNAME;
 541                                 ep = hostbuf + sizeof hostbuf;
 542                                 host.h_name = hostbuf;
 543                                 host.h_aliases = host_aliases;
 544                                 host_aliases[0] = NULL;
 545                                 h_addr_ptrs[0] = (char *)host_addr;
 546                                 h_addr_ptrs[1] = NULL;
 547                                 host.h_addr_list = h_addr_ptrs;
 548                                 if (_res.options & RES_USE_INET6)
 549                                         _map_v4v6_hostent(&host, &bp, &ep);
 550                                 h_errno = NETDB_SUCCESS;
 551                                 *(struct hostent **)rval = &host;
 552                                 return NS_SUCCESS;
 553                         }
 554                         if (!isdigit((unsigned char)*cp) && *cp != '.')
 555                                 break;
 556                 }
 557         if ((isxdigit((unsigned char)name[0]) && strchr(name, ':') != NULL) ||
 558             name[0] == ':')
 559                 for (cp = name;; ++cp) {
 560                         if (!*cp) {
 561                                 if (*--cp == '.')
 562                                         break;
 563                                 /*
 564                                  * All-IPv6-legal, no dot at the end.
 565                                  * Fake up a hostent as if we'd actually
 566                                  * done a lookup.
 567                                  */
 568                                 if (inet_pton(af, name, host_addr) <= 0) {
 569                                         h_errno = HOST_NOT_FOUND;
 570                                         return NS_NOTFOUND;
 571                                 }
 572                                 strncpy(hostbuf, name, MAXDNAME);
 573                                 hostbuf[MAXDNAME] = '\0';
 574                                 bp = hostbuf + MAXDNAME;
 575                                 len = sizeof hostbuf - MAXDNAME;
 576                                 host.h_name = hostbuf;
 577                                 host.h_aliases = host_aliases;
 578                                 host_aliases[0] = NULL;
 579                                 h_addr_ptrs[0] = (char *)host_addr;
 580                                 h_addr_ptrs[1] = NULL;
 581                                 host.h_addr_list = h_addr_ptrs;
 582                                 h_errno = NETDB_SUCCESS;
 583                                 *(struct hostent **)rval = &host;
 584                                 return NS_SUCCESS;
 585                         }
 586                         if (!isxdigit((unsigned char)*cp) && *cp != ':' && *cp != '.')
 587                                 break;
 588                 }
 589
 590         if ((n = res_search(name, C_IN, type, buf.buf, sizeof(buf))) < 0) {
 591                 dprintf("res_search failed (%d)\n", n);
 592                 return NS_UNAVAIL;
 593         }
 594         *(struct hostent **)rval = gethostanswer(&buf, n, name, type);
 595         return (*(struct hostent **)rval != NULL) ? NS_SUCCESS : NS_NOTFOUND;
 596 }
 597
 598 int
 599 _dns_gethostbyaddr(void *rval, void *cb_data, va_list ap)
 600 {
 601         const char *addr;       /* XXX should have been def'd as u_char! */
 602         int len, af;
 603         const u_char *uaddr;
 604         static const u_char mapped[] = { 0,0, 0,0, 0,0, 0,0, 0,0, 0xff,0xff };
 605         static const u_char tunnelled[] = { 0,0, 0,0, 0,0, 0,0, 0,0, 0,0 };
 606         int n, size;
 607         querybuf buf;
 608         struct hostent *hp;
 609         char qbuf[MAXDNAME+1], *qp;
 610 #ifdef SUNSECURITY
 611         struct hostent *rhp;
 612         char **haddr;
 613         u_long old_options;
 614         char hname2[MAXDNAME+1];
 615 #endif /*SUNSECURITY*/
 616
 617         addr = va_arg(ap, const char *);
 618         uaddr = (const u_char *)addr;
 619         len = va_arg(ap, int);
 620         af = va_arg(ap, int);
 621
 622         *(struct hostent **)rval = NULL;
 623
 624         if ((_res.options & RES_INIT) == 0 && res_init() == -1) {
 625                 h_errno = NETDB_INTERNAL;
 626                 return NS_UNAVAIL;
 627         }
 628         if (af == AF_INET6 && len == IN6ADDRSZ &&
 629             (!bcmp(uaddr, mapped, sizeof mapped) ||
 630              !bcmp(uaddr, tunnelled, sizeof tunnelled))) {
 631                 /* Unmap. */
 632                 addr += sizeof mapped;
 633                 uaddr += sizeof mapped;
 634                 af = AF_INET;
 635                 len = INADDRSZ;
 636         }
 637         switch (af) {
 638         case AF_INET:
 639                 size = INADDRSZ;
 640                 break;
 641         case AF_INET6:
 642                 size = IN6ADDRSZ;
 643                 break;
 644         default:
 645                 errno = EAFNOSUPPORT;
 646                 h_errno = NETDB_INTERNAL;
 647                 return NS_UNAVAIL;
 648         }
 649         if (size != len) {
 650                 errno = EINVAL;
 651                 h_errno = NETDB_INTERNAL;
 652                 return NS_UNAVAIL;
 653         }
 654         switch (af) {
 655         case AF_INET:
 656                 (void) sprintf(qbuf, "%u.%u.%u.%u.in-addr.arpa",
 657                                (uaddr[3] & 0xff),
 658                                (uaddr[2] & 0xff),
 659                                (uaddr[1] & 0xff),
 660                                (uaddr[0] & 0xff));
 661                 break;
 662         case AF_INET6:
 663                 qp = qbuf;
 664                 for (n = IN6ADDRSZ - 1; n >= 0; n--) {
 665                         qp += SPRINTF((qp, "%x.%x.",
 666                                        uaddr[n] & 0xf,
 667                                        (uaddr[n] >> 4) & 0xf));
 668                 }
 669                 strcpy(qp, "ip6.int");
 670                 break;
 671         default:
 672                 abort();
 673         }
 674         n = res_query(qbuf, C_IN, T_PTR, (u_char *)buf.buf, sizeof buf.buf);
 675         if (n < 0) {
 676                 dprintf("res_query failed (%d)\n", n);
 677                 return NS_UNAVAIL;
 678         }
 679         if (n > sizeof buf.buf) {
 680                 dprintf("static buffer is too small (%d)\n", n);
 681                 return NS_UNAVAIL;
 682         }
 683         if (!(hp = gethostanswer(&buf, n, qbuf, T_PTR)))
 684                 return NS_NOTFOUND;   /* h_errno was set by gethostanswer() */
 685 #ifdef SUNSECURITY
 686         if (af == AF_INET) {
 687             /*
 688              * turn off search as the name should be absolute,
 689              * 'localhost' should be matched by defnames
 690              */
 691             strncpy(hname2, hp->h_name, MAXDNAME);
 692             hname2[MAXDNAME] = '\0';
 693             old_options = _res.options;
 694             _res.options &= ~RES_DNSRCH;
 695             _res.options |= RES_DEFNAMES;
 696             if (!(rhp = gethostbyname(hname2))) {
 697                 syslog(LOG_NOTICE|LOG_AUTH,
 698                        "gethostbyaddr: No A record for %s (verifying [%s])",
 699                        hname2, inet_ntoa(*((struct in_addr *)addr)));
 700                 _res.options = old_options;
 701                 h_errno = HOST_NOT_FOUND;
 702                 return NS_NOTFOUND;
 703             }
 704             _res.options = old_options;
 705             for (haddr = rhp->h_addr_list; *haddr; haddr++)
 706                 if (!memcmp(*haddr, addr, INADDRSZ))
 707                         break;
 708             if (!*haddr) {
 709                 syslog(LOG_NOTICE|LOG_AUTH,
 710                        "gethostbyaddr: A record of %s != PTR record [%s]",
 711                        hname2, inet_ntoa(*((struct in_addr *)addr)));
 712                 h_errno = HOST_NOT_FOUND;
 713                 return NS_NOTFOUND;
 714             }
 715         }
 716 #endif /*SUNSECURITY*/
 717         hp->h_addrtype = af;
 718         hp->h_length = len;
 719         bcopy(addr, host_addr, len);
 720         h_addr_ptrs[0] = (char *)host_addr;
 721         h_addr_ptrs[1] = NULL;
 722         if (af == AF_INET && (_res.options & RES_USE_INET6)) {
 723                 _map_v4v6_address((char*)host_addr, (char*)host_addr);
 724                 hp->h_addrtype = AF_INET6;
 725                 hp->h_length = IN6ADDRSZ;
 726         }
 727         h_errno = NETDB_SUCCESS;
 728         *(struct hostent **)rval = hp;
 729         return (hp != NULL) ? NS_SUCCESS : NS_NOTFOUND;
 730 }
 731
 732 #ifdef RESOLVSORT
 733 static void
 734 addrsort(ap, num)
 735         char **ap;
 736         int num;
 737 {
 738         int i, j;
 739         char **p;
 740         short aval[MAXADDRS];
 741         int needsort = 0;
 742
 743         p = ap;
 744         for (i = 0; i < num; i++, p++) {
 745             for (j = 0 ; (unsigned)j < _res.nsort; j++)
 746                 if (_res.sort_list[j].addr.s_addr ==
 747                     (((struct in_addr *)(*p))->s_addr & _res.sort_list[j].mask))
 748                         break;
 749             aval[i] = j;
 750             if (needsort == 0 && i > 0 && j < aval[i-1])
 751                 needsort = i;
 752         }
 753         if (!needsort)
 754             return;
 755
 756         while (needsort < num) {
 757             for (j = needsort - 1; j >= 0; j--) {
 758                 if (aval[j] > aval[j+1]) {
 759                     char *hp;
 760
 761                     i = aval[j];
 762                     aval[j] = aval[j+1];
 763                     aval[j+1] = i;
 764
 765                     hp = ap[j];
 766                     ap[j] = ap[j+1];
 767                     ap[j+1] = hp;
 768
 769                 } else
 770                     break;
 771             }
 772             needsort++;
 773         }
 774 }
 775 #endif
 776 void
 777 _sethostdnsent(stayopen)
 778         int stayopen;
 779 {
 780         if ((_res.options & RES_INIT) == 0 && res_init() == -1)
 781                 return;
 782         if (stayopen)
 783                 _res.options |= RES_STAYOPEN | RES_USEVC;
 784 }
 785
 786 void
 787 _endhostdnsent()
 788 {
 789         _res.options &= ~(RES_STAYOPEN | RES_USEVC);
 790         res_close();
 791 }