resolv/nss_dns/dns-host.c

   1 /* Copyright (C) 1996-2000, 2001, 2002 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Extended from original form by Ulrich Drepper <drepper@cygnus.com>, 1996.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 /* Parts of this file are plain copies of the file `gethtnamadr.c' from
  21    the bind package and it has the following copyright.  */
  22
  23 /*
  24  * ++Copyright++ 1985, 1988, 1993
  25  * -
  26  * Copyright (c) 1985, 1988, 1993
  27  *    The Regents of the University of California.  All rights reserved.
  28  *
  29  * Redistribution and use in source and binary forms, with or without
  30  * modification, are permitted provided that the following conditions
  31  * are met:
  32  * 1. Redistributions of source code must retain the above copyright
  33  *    notice, this list of conditions and the following disclaimer.
  34  * 2. Redistributions in binary form must reproduce the above copyright
  35  *    notice, this list of conditions and the following disclaimer in the
  36  *    documentation and/or other materials provided with the distribution.
  37  * 4. Neither the name of the University nor the names of its contributors
  38  *    may be used to endorse or promote products derived from this software
  39  *    without specific prior written permission.
  40  *
  41  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  42  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  43  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  44  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  45  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  46  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  47  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  48  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  49  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  50  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  51  * SUCH DAMAGE.
  52  * -
  53  * Portions Copyright (c) 1993 by Digital Equipment Corporation.
  54  *
  55  * Permission to use, copy, modify, and distribute this software for any
  56  * purpose with or without fee is hereby granted, provided that the above
  57  * copyright notice and this permission notice appear in all copies, and that
  58  * the name of Digital Equipment Corporation not be used in advertising or
  59  * publicity pertaining to distribution of the document or software without
  60  * specific, written prior permission.
  61  *
  62  * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
  63  * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
  64  * OF MERCHANTABILITY AND FITNESS.   IN NO EVENT SHALL DIGITAL EQUIPMENT
  65  * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
  66  * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
  67  * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
  68  * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
  69  * SOFTWARE.
  70  * -
  71  * --Copyright--
  72  */
  73
  74 #include <ctype.h>
  75 #include <errno.h>
  76 #include <netdb.h>
  77 #include <stdio.h>
  78 #include <stdlib.h>
  79 #include <stddef.h>
  80 #include <string.h>
  81 #include <sys/syslog.h>
  82
  83 #include "nsswitch.h"
  84
  85 /* Get implementation for some internal functions.  */
  86 #include <resolv/mapv4v6addr.h>
  87 #include <resolv/mapv4v6hostent.h>
  88
  89 #define RESOLVSORT
  90
  91 /* Maximum number of aliases we allow.  */
  92 #define MAX_NR_ALIASES  48
  93 #define MAX_NR_ADDRS    48
  94
  95 #if PACKETSZ > 65536
  96 # define MAXPACKET      PACKETSZ
  97 #else
  98 # define MAXPACKET      65536
  99 #endif
 100 /* As per RFC 1034 and 1035 a host name cannot exceed 255 octets in length.  */
 101 #ifdef MAXHOSTNAMELEN
 102 # undef MAXHOSTNAMELEN
 103 #endif
 104 #define MAXHOSTNAMELEN 256
 105
 106 static const char AskedForGot[] = "\
 107 gethostby*.getanswer: asked for \"%s\", got \"%s\"";
 108
 109
 110 /* We need this time later.  */
 111 typedef union querybuf
 112 {
 113   HEADER hdr;
 114   u_char buf[MAXPACKET];
 115 } querybuf;
 116
 117 /* These functions are defined in res_comp.c.  */
 118 #define NS_MAXCDNAME    255     /* maximum compressed domain name */
 119 extern int __ns_name_ntop (const u_char *, char *, size_t);
 120 extern int __ns_name_unpack (const u_char *, const u_char *,
 121                              const u_char *, u_char *, size_t);
 122
 123
 124 static enum nss_status getanswer_r (const querybuf *answer, int anslen,
 125                                     const char *qname, int qtype,
 126                                     struct hostent *result, char *buffer,
 127                                     size_t buflen, int *errnop, int *h_errnop,
 128                                     int map);
 129
 130 enum nss_status
 131 _nss_dns_gethostbyname2_r (const char *name, int af, struct hostent *result,
 132                            char *buffer, size_t buflen, int *errnop,
 133                            int *h_errnop)
 134 {
 135   union
 136   {
 137     querybuf *buf;
 138     u_char *ptr;
 139   } host_buffer;
 140   querybuf *orig_host_buffer;
 141   char tmp[NS_MAXDNAME];
 142   int size, type, n;
 143   const char *cp;
 144   int map = 0;
 145   int olderr = errno;
 146   enum nss_status status;
 147
 148   if ((_res.options & RES_INIT) == 0 && __res_ninit (&_res) == -1)
 149     return NSS_STATUS_UNAVAIL;
 150
 151   switch (af) {
 152   case AF_INET:
 153     size = INADDRSZ;
 154     type = T_A;
 155     break;
 156   case AF_INET6:
 157     size = IN6ADDRSZ;
 158     type = T_AAAA;
 159     break;
 160   default:
 161     *h_errnop = NO_DATA;
 162     *errnop = EAFNOSUPPORT;
 163     return NSS_STATUS_UNAVAIL;
 164   }
 165
 166   result->h_addrtype = af;
 167   result->h_length = size;
 168
 169   /*
 170    * if there aren't any dots, it could be a user-level alias.
 171    * this is also done in res_query() since we are not the only
 172    * function that looks up host names.
 173    */
 174   if (strchr (name, '.') == NULL
 175       && (cp = res_hostalias (&_res, name, tmp, sizeof (tmp))) != NULL)
 176     name = cp;
 177
 178   host_buffer.buf = orig_host_buffer = (querybuf *) alloca (1024);
 179
 180   n = __libc_res_nsearch (&_res, name, C_IN, type, host_buffer.buf->buf,
 181                           1024, &host_buffer.ptr);
 182   if (n < 0)
 183     {
 184       enum nss_status status = (errno == ECONNREFUSED
 185                                 ? NSS_STATUS_UNAVAIL : NSS_STATUS_NOTFOUND);
 186       *h_errnop = h_errno;
 187       if (h_errno == TRY_AGAIN)
 188         *errnop = EAGAIN;
 189       else
 190         __set_errno (olderr);
 191
 192       /* If we are looking for a IPv6 address and mapping is enabled
 193          by having the RES_USE_INET6 bit in _res.options set, we try
 194          another lookup.  */
 195       if (af == AF_INET6 && (_res.options & RES_USE_INET6))
 196         n = __libc_res_nsearch (&_res, name, C_IN, T_A, host_buffer.buf->buf,
 197                                 host_buffer.buf != orig_host_buffer
 198                                 ? MAXPACKET : 1024, &host_buffer.ptr);
 199
 200       if (n < 0)
 201         {
 202           if (host_buffer.buf != orig_host_buffer)
 203             free (host_buffer.buf);
 204           return status;
 205         }
 206
 207       map = 1;
 208
 209       result->h_addrtype = AF_INET;
 210       result->h_length = INADDRSZ;;
 211     }
 212
 213   status = getanswer_r (host_buffer.buf, n, name, type, result, buffer, buflen,
 214                         errnop, h_errnop, map);
 215   if (host_buffer.buf != orig_host_buffer)
 216     free (host_buffer.buf);
 217   return status;
 218 }
 219
 220
 221 enum nss_status
 222 _nss_dns_gethostbyname_r (const char *name, struct hostent *result,
 223                           char *buffer, size_t buflen, int *errnop,
 224                           int *h_errnop)
 225 {
 226   enum nss_status status = NSS_STATUS_NOTFOUND;
 227
 228   if (_res.options & RES_USE_INET6)
 229     status = _nss_dns_gethostbyname2_r (name, AF_INET6, result, buffer,
 230                                         buflen, errnop, h_errnop);
 231   if (status == NSS_STATUS_NOTFOUND)
 232     status = _nss_dns_gethostbyname2_r (name, AF_INET, result, buffer,
 233                                         buflen, errnop, h_errnop);
 234
 235   return status;
 236 }
 237
 238
 239 enum nss_status
 240 _nss_dns_gethostbyaddr_r (const void *addr, socklen_t len, int af,
 241                           struct hostent *result, char *buffer, size_t buflen,
 242                           int *errnop, int *h_errnop)
 243 {
 244   static const u_char mapped[] = { 0,0, 0,0, 0,0, 0,0, 0,0, 0xff,0xff };
 245   static const u_char tunnelled[] = { 0,0, 0,0, 0,0, 0,0, 0,0, 0,0 };
 246   static const u_char v6local[] = { 0,0, 0,1 };
 247   const u_char *uaddr = (const u_char *)addr;
 248   struct host_data
 249   {
 250     char *aliases[MAX_NR_ALIASES];
 251     unsigned char host_addr[16];        /* IPv4 or IPv6 */
 252     char *h_addr_ptrs[MAX_NR_ADDRS + 1];
 253     char linebuffer[0];
 254   } *host_data = (struct host_data *) buffer;
 255   union
 256   {
 257     querybuf *buf;
 258     u_char *ptr;
 259   } host_buffer;
 260   querybuf *orig_host_buffer;
 261   char qbuf[MAXDNAME+1], *qp = NULL;
 262   size_t size;
 263   int n, status;
 264   int olderr = errno;
 265
 266   if ((_res.options & RES_INIT) == 0 && __res_ninit (&_res) == -1)
 267     return NSS_STATUS_UNAVAIL;
 268
 269   if (af == AF_INET6 && len == IN6ADDRSZ
 270       && (memcmp (uaddr, mapped, sizeof mapped) == 0
 271           || (memcmp (uaddr, tunnelled, sizeof tunnelled) == 0
 272               && memcmp (&uaddr[sizeof tunnelled], v6local, sizeof v6local))))
 273     {
 274       /* Unmap. */
 275       addr += sizeof mapped;
 276       uaddr += sizeof mapped;
 277       af = AF_INET;
 278       len = INADDRSZ;
 279     }
 280
 281   switch (af)
 282     {
 283     case AF_INET:
 284       size = INADDRSZ;
 285       break;
 286     case AF_INET6:
 287       size = IN6ADDRSZ;
 288       break;
 289     default:
 290       *errnop = EAFNOSUPPORT;
 291       *h_errnop = NETDB_INTERNAL;
 292       return NSS_STATUS_UNAVAIL;
 293     }
 294   if (size > len)
 295     {
 296       *errnop = EAFNOSUPPORT;
 297       *h_errnop = NETDB_INTERNAL;
 298       return NSS_STATUS_UNAVAIL;
 299     }
 300
 301   switch (af)
 302     {
 303     case AF_INET:
 304       sprintf (qbuf, "%u.%u.%u.%u.in-addr.arpa", (uaddr[3] & 0xff),
 305                (uaddr[2] & 0xff), (uaddr[1] & 0xff), (uaddr[0] & 0xff));
 306       break;
 307     case AF_INET6:
 308       qp = qbuf;
 309       for (n = IN6ADDRSZ - 1; n >= 0; n--)
 310         qp += sprintf (qp, "%x.%x.", uaddr[n] & 0xf, (uaddr[n] >> 4) & 0xf);
 311       strcpy (qp, "ip6.arpa");
 312       break;
 313     default:
 314       /* Cannot happen.  */
 315       break;
 316     }
 317
 318   host_buffer.buf = orig_host_buffer = (querybuf *) alloca (1024);
 319
 320   n = __libc_res_nquery (&_res, qbuf, C_IN, T_PTR, host_buffer.buf->buf,
 321                          1024, &host_buffer.ptr);
 322   if (n < 0 && af == AF_INET6)
 323     {
 324       strcpy (qp, "ip6.int");
 325       n = __libc_res_nquery (&_res, qbuf, C_IN, T_PTR, host_buffer.buf->buf,
 326                              host_buffer.buf != orig_host_buffer
 327                              ? MAXPACKET : 1024, &host_buffer.ptr);
 328     }
 329   if (n < 0)
 330     {
 331       *h_errnop = h_errno;
 332       __set_errno (olderr);
 333       if (host_buffer.buf != orig_host_buffer)
 334         free (host_buffer.buf);
 335       return errno == ECONNREFUSED ? NSS_STATUS_UNAVAIL : NSS_STATUS_NOTFOUND;
 336     }
 337
 338   status = getanswer_r (host_buffer.buf, n, qbuf, T_PTR, result, buffer, buflen,
 339                         errnop, h_errnop, 0 /* XXX */);
 340   if (host_buffer.buf != orig_host_buffer)
 341     free (host_buffer.buf);
 342   if (status != NSS_STATUS_SUCCESS)
 343     {
 344       *h_errnop = h_errno;
 345       *errnop = errno;
 346       return status;
 347     }
 348
 349 #ifdef SUNSECURITY
 350   This is not implemented because it is not possible to use the current
 351   source from bind in a multi-threaded program.
 352 #endif
 353
 354   result->h_addrtype = af;
 355   result->h_length = len;
 356   memcpy (host_data->host_addr, addr, len);
 357   host_data->h_addr_ptrs[0] = (char *) host_data->host_addr;
 358   host_data->h_addr_ptrs[1] = NULL;
 359 #if 0
 360   /* XXX I think this is wrong.  Why should an IPv4 address be
 361      converted to IPv6 if the user explicitly asked for IPv4?  */
 362   if (af == AF_INET && (_res.options & RES_USE_INET6))
 363     {
 364       map_v4v6_address ((char *) host_data->host_addr,
 365                         (char *) host_data->host_addr);
 366       result->h_addrtype = AF_INET6;
 367       result->h_length = IN6ADDRSZ;
 368     }
 369 #endif
 370   *h_errnop = NETDB_SUCCESS;
 371   return NSS_STATUS_SUCCESS;
 372 }
 373
 374 #ifdef RESOLVSORT
 375 static void addrsort (char **ap, int num);
 376
 377 static void
 378 addrsort (char **ap, int num)
 379 {
 380   int i, j;
 381   char **p;
 382   short aval[MAX_NR_ADDRS];
 383   int needsort = 0;
 384
 385   p = ap;
 386   if (num > MAX_NR_ADDRS)
 387     num = MAX_NR_ADDRS;
 388   for (i = 0; i < num; i++, p++)
 389     {
 390       for (j = 0 ; (unsigned)j < _res.nsort; j++)
 391         if (_res.sort_list[j].addr.s_addr ==
 392             (((struct in_addr *)(*p))->s_addr & _res.sort_list[j].mask))
 393           break;
 394       aval[i] = j;
 395       if (needsort == 0 && i > 0 && j < aval[i-1])
 396         needsort = i;
 397     }
 398   if (!needsort)
 399     return;
 400
 401   while (needsort++ < num)
 402     for (j = needsort - 2; j >= 0; j--)
 403       if (aval[j] > aval[j+1])
 404         {
 405           char *hp;
 406
 407           i = aval[j];
 408           aval[j] = aval[j+1];
 409           aval[j+1] = i;
 410
 411           hp = ap[j];
 412           ap[j] = ap[j+1];
 413           ap[j+1] = hp;
 414         }
 415       else
 416         break;
 417 }
 418 #endif
 419
 420 static enum nss_status
 421 getanswer_r (const querybuf *answer, int anslen, const char *qname, int qtype,
 422              struct hostent *result, char *buffer, size_t buflen,
 423              int *errnop, int *h_errnop, int map)
 424 {
 425   struct host_data
 426   {
 427     char *aliases[MAX_NR_ALIASES];
 428     unsigned char host_addr[16];        /* IPv4 or IPv6 */
 429     char *h_addr_ptrs[0];
 430   } *host_data = (struct host_data *) buffer;
 431   int linebuflen = buflen - sizeof (struct host_data);
 432   register const HEADER *hp;
 433   const u_char *end_of_message, *cp;
 434   int n, ancount, qdcount;
 435   int haveanswer, had_error;
 436   char *bp, **ap, **hap;
 437   char tbuf[MAXDNAME];
 438   const char *tname;
 439   int (*name_ok) (const char *);
 440   u_char packtmp[NS_MAXCDNAME];
 441   int have_to_map = 0;
 442
 443   if (__builtin_expect (linebuflen, 0) < 0)
 444     {
 445       /* The buffer is too small.  */
 446     too_small:
 447       *errnop = ERANGE;
 448       *h_errnop = NETDB_INTERNAL;
 449       return NSS_STATUS_TRYAGAIN;
 450     }
 451
 452   tname = qname;
 453   result->h_name = NULL;
 454   end_of_message = answer->buf + anslen;
 455   switch (qtype)
 456     {
 457     case T_A:
 458     case T_AAAA:
 459       name_ok = res_hnok;
 460       break;
 461     case T_PTR:
 462       name_ok = res_dnok;
 463       break;
 464     default:
 465       *errnop = ENOENT;
 466       return NSS_STATUS_UNAVAIL;  /* XXX should be abort(); */
 467     }
 468
 469   /*
 470    * find first satisfactory answer
 471    */
 472   hp = &answer->hdr;
 473   ancount = ntohs (hp->ancount);
 474   qdcount = ntohs (hp->qdcount);
 475   cp = answer->buf + HFIXEDSZ;
 476   if (__builtin_expect (qdcount, 1) != 1)
 477     {
 478       *h_errnop = NO_RECOVERY;
 479       return NSS_STATUS_UNAVAIL;
 480     }
 481   if (sizeof (struct host_data) + (ancount + 1) * sizeof (char *) >= buflen)
 482     goto too_small;
 483   bp = (char *) &host_data->h_addr_ptrs[ancount + 1];
 484   linebuflen -= (ancount + 1) * sizeof (char *);
 485
 486   n = __ns_name_unpack (answer->buf, end_of_message, cp,
 487                         packtmp, sizeof packtmp);
 488   if (n != -1 && __ns_name_ntop (packtmp, bp, linebuflen) == -1)
 489     {
 490       if (__builtin_expect (errno, 0) == EMSGSIZE)
 491         goto too_small;
 492
 493       n = -1;
 494     }
 495
 496   if (n > 0 && bp[0] == '.')
 497     bp[0] = '\0';
 498
 499   if (n < 0 || (*name_ok) (bp) == 0)
 500     {
 501       *errnop = errno;
 502       *h_errnop = NO_RECOVERY;
 503       return NSS_STATUS_UNAVAIL;
 504     }
 505   cp += n + QFIXEDSZ;
 506
 507   if (qtype == T_A || qtype == T_AAAA)
 508     {
 509       /* res_send() has already verified that the query name is the
 510        * same as the one we sent; this just gets the expanded name
 511        * (i.e., with the succeeding search-domain tacked on).
 512        */
 513       n = strlen (bp) + 1;             /* for the \0 */
 514       if (n >= MAXHOSTNAMELEN)
 515         {
 516           *h_errnop = NO_RECOVERY;
 517           *errnop = ENOENT;
 518           return NSS_STATUS_TRYAGAIN;
 519         }
 520       result->h_name = bp;
 521       bp += n;
 522       linebuflen -= n;
 523       if (linebuflen < 0)
 524         goto too_small;
 525       /* The qname can be abbreviated, but h_name is now absolute. */
 526       qname = result->h_name;
 527     }
 528
 529   ap = host_data->aliases;
 530   *ap = NULL;
 531   result->h_aliases = host_data->aliases;
 532   hap = host_data->h_addr_ptrs;
 533   *hap = NULL;
 534   result->h_addr_list = host_data->h_addr_ptrs;
 535   haveanswer = 0;
 536   had_error = 0;
 537
 538   while (ancount-- > 0 && cp < end_of_message && had_error == 0)
 539     {
 540       int type, class;
 541
 542       n = __ns_name_unpack (answer->buf, end_of_message, cp,
 543                             packtmp, sizeof packtmp);
 544       if (n != -1 && __ns_name_ntop (packtmp, bp, linebuflen) == -1)
 545         {
 546           if (__builtin_expect (errno, 0) == EMSGSIZE)
 547             goto too_small;
 548
 549           n = -1;
 550         }
 551
 552       if (n < 0 || (*name_ok) (bp) == 0)
 553         {
 554           ++had_error;
 555           continue;
 556         }
 557       cp += n;                          /* name */
 558       type = ns_get16 (cp);
 559       cp += INT16SZ;                    /* type */
 560       class = ns_get16 (cp);
 561       cp += INT16SZ + INT32SZ;          /* class, TTL */
 562       n = ns_get16 (cp);
 563       cp += INT16SZ;                    /* len */
 564       if (class != C_IN)
 565         {
 566           /* XXX - debug? syslog? */
 567           cp += n;
 568           continue;                     /* XXX - had_error++ ? */
 569         }
 570
 571       if ((qtype ==T_A || qtype == T_AAAA) && type == T_CNAME)
 572         {
 573           if (ap >= &host_data->aliases[MAX_NR_ALIASES - 1])
 574             continue;
 575           n = dn_expand (answer->buf, end_of_message, cp, tbuf, sizeof tbuf);
 576           if (n < 0 || (*name_ok) (tbuf) == 0)
 577             {
 578               ++had_error;
 579               continue;
 580             }
 581           cp += n;
 582           /* Store alias.  */
 583           *ap++ = bp;
 584           n = strlen (bp) + 1;          /* For the \0.  */
 585           if (__builtin_expect (n, 0) >= MAXHOSTNAMELEN)
 586             {
 587               ++had_error;
 588               continue;
 589             }
 590           bp += n;
 591           linebuflen -= n;
 592           /* Get canonical name.  */
 593           n = strlen (tbuf) + 1;        /* For the \0.  */
 594           if (__builtin_expect (n > linebuflen, 0))
 595             goto too_small;
 596           if (__builtin_expect (n, 0) >= MAXHOSTNAMELEN)
 597             {
 598               ++had_error;
 599               continue;
 600             }
 601           result->h_name = bp;
 602           bp = __mempcpy (bp, tbuf, n); /* Cannot overflow.  */
 603           linebuflen -= n;
 604           continue;
 605         }
 606
 607       if (qtype == T_PTR && type == T_CNAME)
 608         {
 609           n = dn_expand (answer->buf, end_of_message, cp, tbuf, sizeof tbuf);
 610           if (n < 0 || res_dnok (tbuf) == 0)
 611             {
 612               ++had_error;
 613               continue;
 614             }
 615           cp += n;
 616           /* Get canonical name.  */
 617           n = strlen (tbuf) + 1;   /* For the \0.  */
 618           if (__builtin_expect (n > linebuflen, 0))
 619             goto too_small;
 620           if (__builtin_expect (n, 0) >= MAXHOSTNAMELEN)
 621             {
 622               ++had_error;
 623               continue;
 624             }
 625           tname = bp;
 626           bp = __mempcpy (bp, tbuf, n); /* Cannot overflow.  */
 627           linebuflen -= n;
 628           continue;
 629         }
 630       if (__builtin_expect (type == T_SIG, 0)
 631           || __builtin_expect (type == T_KEY, 0)
 632           || __builtin_expect (type == T_NXT, 0))
 633         {
 634           /* We don't support DNSSEC yet.  For now, ignore the record
 635              and send a low priority message to syslog.  */
 636           syslog (LOG_DEBUG | LOG_AUTH,
 637                "gethostby*.getanswer: asked for \"%s %s %s\", got type \"%s\"",
 638                   qname, p_class (C_IN), p_type(qtype), p_type (type));
 639           cp += n;
 640           continue;
 641         }
 642
 643       if (type == T_A && qtype == T_AAAA && map)
 644         have_to_map = 1;
 645       else if (__builtin_expect (type != qtype, 0))
 646         {
 647           syslog (LOG_NOTICE | LOG_AUTH,
 648                "gethostby*.getanswer: asked for \"%s %s %s\", got type \"%s\"",
 649                   qname, p_class (C_IN), p_type (qtype), p_type (type));
 650           cp += n;
 651           continue;                     /* XXX - had_error++ ? */
 652         }
 653
 654       switch (type)
 655         {
 656         case T_PTR:
 657           if (__strcasecmp (tname, bp) != 0)
 658             {
 659               syslog (LOG_NOTICE | LOG_AUTH, AskedForGot, qname, bp);
 660               cp += n;
 661               continue;                 /* XXX - had_error++ ? */
 662             }
 663
 664           n = __ns_name_unpack (answer->buf, end_of_message, cp,
 665                                 packtmp, sizeof packtmp);
 666           if (n != -1 && __ns_name_ntop (packtmp, bp, linebuflen) == -1)
 667             {
 668               if (__builtin_expect (errno, 0) == EMSGSIZE)
 669                 goto too_small;
 670
 671               n = -1;
 672             }
 673
 674           if (n < 0 || res_hnok (bp) == 0)
 675             {
 676               ++had_error;
 677               break;
 678             }
 679 #if MULTI_PTRS_ARE_ALIASES
 680           cp += n;
 681           if (haveanswer == 0)
 682             result->h_name = bp;
 683           else if (ap < &host_data->aliases[MAXALIASES-1])
 684             *ap++ = bp;
 685           else
 686             n = -1;
 687           if (n != -1)
 688             {
 689               n = strlen (bp) + 1;      /* for the \0 */
 690               if (__builtin_expect (n, 0) >= MAXHOSTNAMELEN)
 691                 {
 692                   ++had_error;
 693                   break;
 694                 }
 695               bp += n;
 696               linebuflen -= n;
 697             }
 698           break;
 699 #else
 700           result->h_name = bp;
 701           if (have_to_map)
 702             {
 703               n = strlen (bp) + 1;      /* for the \0 */
 704               if (n >= MAXHOSTNAMELEN)
 705                 {
 706                   ++had_error;
 707                   break;
 708                 }
 709               bp += n;
 710               linebuflen -= n;
 711               map_v4v6_hostent (result, &bp, &linebuflen);
 712             }
 713           *h_errnop = NETDB_SUCCESS;
 714           return NSS_STATUS_SUCCESS;
 715 #endif
 716         case T_A:
 717         case T_AAAA:
 718           if (__builtin_expect (strcasecmp (result->h_name, bp), 0) != 0)
 719             {
 720               syslog (LOG_NOTICE | LOG_AUTH, AskedForGot, result->h_name, bp);
 721               cp += n;
 722               continue;                 /* XXX - had_error++ ? */
 723             }
 724           if (n != result->h_length)
 725             {
 726               cp += n;
 727               continue;
 728             }
 729           if (!haveanswer)
 730             {
 731               register int nn;
 732
 733               result->h_name = bp;
 734               nn = strlen (bp) + 1;     /* for the \0 */
 735               bp += nn;
 736               linebuflen -= nn;
 737             }
 738
 739           linebuflen -= sizeof (align) - ((u_long) bp % sizeof (align));
 740           bp += sizeof (align) - ((u_long) bp % sizeof (align));
 741
 742           if (__builtin_expect (n > linebuflen, 0))
 743             goto too_small;
 744           bp = __mempcpy (*hap++ = bp, cp, n);
 745           cp += n;
 746           linebuflen -= n;
 747           break;
 748         default:
 749           abort ();
 750         }
 751       if (had_error == 0)
 752         ++haveanswer;
 753     }
 754
 755   if (haveanswer > 0)
 756     {
 757       *ap = NULL;
 758       *hap = NULL;
 759 #if defined RESOLVSORT
 760       /*
 761        * Note: we sort even if host can take only one address
 762        * in its return structures - should give it the "best"
 763        * address in that case, not some random one
 764        */
 765       if (_res.nsort && haveanswer > 1 && qtype == T_A)
 766         addrsort (host_data->h_addr_ptrs, haveanswer);
 767 #endif /*RESOLVSORT*/
 768
 769       if (result->h_name == NULL)
 770         {
 771           n = strlen (qname) + 1;       /* For the \0.  */
 772           if (n > linebuflen)
 773             goto too_small;
 774           if (n >= MAXHOSTNAMELEN)
 775             goto no_recovery;
 776           result->h_name = bp;
 777           bp = __mempcpy (bp, qname, n);        /* Cannot overflow.  */
 778           linebuflen -= n;
 779         }
 780
 781       if (have_to_map)
 782         map_v4v6_hostent (result, &bp, &linebuflen);
 783       *h_errnop = NETDB_SUCCESS;
 784       return NSS_STATUS_SUCCESS;
 785     }
 786  no_recovery:
 787   *h_errnop = NO_RECOVERY;
 788   *errnop = ENOENT;
 789   return NSS_STATUS_TRYAGAIN;
 790 }