resolv/res_queriesmatch.c

   1 /* Check if two DNS packets contain the same query.
   2    Copyright (C) 2016-2022 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   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, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 /*
  20  * Copyright (c) 1985, 1989, 1993
  21  *    The Regents of the University of California.  All rights reserved.
  22  *
  23  * Redistribution and use in source and binary forms, with or without
  24  * modification, are permitted provided that the following conditions
  25  * are met:
  26  * 1. Redistributions of source code must retain the above copyright
  27  *    notice, this list of conditions and the following disclaimer.
  28  * 2. Redistributions in binary form must reproduce the above copyright
  29  *    notice, this list of conditions and the following disclaimer in the
  30  *    documentation and/or other materials provided with the distribution.
  31  * 4. Neither the name of the University nor the names of its contributors
  32  *    may be used to endorse or promote products derived from this software
  33  *    without specific prior written permission.
  34  *
  35  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  36  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  37  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  38  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  39  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  40  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  41  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  42  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  43  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  44  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  45  * SUCH DAMAGE.
  46  */
  47
  48 /*
  49  * Portions Copyright (c) 1993 by Digital Equipment Corporation.
  50  *
  51  * Permission to use, copy, modify, and distribute this software for any
  52  * purpose with or without fee is hereby granted, provided that the above
  53  * copyright notice and this permission notice appear in all copies, and that
  54  * the name of Digital Equipment Corporation not be used in advertising or
  55  * publicity pertaining to distribution of the document or software without
  56  * specific, written prior permission.
  57  *
  58  * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
  59  * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
  60  * OF MERCHANTABILITY AND FITNESS.   IN NO EVENT SHALL DIGITAL EQUIPMENT
  61  * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
  62  * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
  63  * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
  64  * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
  65  * SOFTWARE.
  66  */
  67
  68 /*
  69  * Portions Copyright (c) 1996-1999 by Internet Software Consortium.
  70  *
  71  * Permission to use, copy, modify, and distribute this software for any
  72  * purpose with or without fee is hereby granted, provided that the above
  73  * copyright notice and this permission notice appear in all copies.
  74  *
  75  * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
  76  * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
  77  * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
  78  * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
  79  * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
  80  * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
  81  * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
  82  * SOFTWARE.
  83  */
  84
  85 #include <resolv.h>
  86
  87 /* Author: paul vixie, 29may94.  */
  88 int
  89 __libc_res_queriesmatch (const unsigned char *buf1, const unsigned char *eom1,
  90                          const unsigned char *buf2, const unsigned char *eom2)
  91 {
  92   if (eom1 - buf1 < HFIXEDSZ || eom2 - buf2 < HFIXEDSZ)
  93     return -1;
  94
  95   /* Only header section present in replies to dynamic update
  96      packets.  */
  97   if ((((HEADER *) buf1)->opcode == ns_o_update) &&
  98       (((HEADER *) buf2)->opcode == ns_o_update))
  99     return 1;
 100
 101   /* Note that we initially do not convert QDCOUNT to the host byte
 102      order.  We can compare it with the second buffer's QDCOUNT
 103      value without doing this.  */
 104   int qdcount = ((HEADER *) buf1)->qdcount;
 105   if (qdcount != ((HEADER *) buf2)->qdcount)
 106     return 0;
 107
 108   qdcount = htons (qdcount);
 109   const unsigned char *cp = buf1 + HFIXEDSZ;
 110
 111   while (qdcount-- > 0)
 112     {
 113       char tname[MAXDNAME+1];
 114       int n, ttype, tclass;
 115
 116       n = __libc_dn_expand (buf1, eom1, cp, tname, sizeof tname);
 117       if (n < 0)
 118         return -1;
 119       cp += n;
 120       if (eom1 - cp < 4)
 121         return -1;
 122       NS_GET16 (ttype, cp);
 123       NS_GET16 (tclass, cp);
 124       if (!__libc_res_nameinquery (tname, ttype, tclass, buf2, eom2))
 125         return 0;
 126     }
 127   return 1;
 128 }
 129 libc_hidden_def (__libc_res_queriesmatch)