resolv/res_data.c

   1 /* Miscellaneous definitions for libresolv.
   2    Copyright (C) 1995-2020 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) 1995-1999 by Internet Software Consortium.
  21  *
  22  * Permission to use, copy, modify, and distribute this software for any
  23  * purpose with or without fee is hereby granted, provided that the above
  24  * copyright notice and this permission notice appear in all copies.
  25  *
  26  * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
  27  * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
  28  * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
  29  * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
  30  * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
  31  * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
  32  * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
  33  * SOFTWARE.
  34  */
  35
  36 #include <resolv.h>
  37
  38 /* This function belongs to libresolv, which is why it is not included
  39    in res-close.c.  */
  40 void
  41 __res_close (void)
  42 {
  43   /* Some programs call res_close before res_init.  Since _res._vcsock
  44      isn't explicitly initialized, these means that we could call
  45      close (0), which might lead to some security problems.  Therefore
  46      we check if res_init was called before by looking at the RES_INIT
  47      bit in _res.options.  If it hasn't been set we bail out
  48      early.  */
  49   if ((_res.options & RES_INIT) == 0)
  50     return;
  51   /* We don't free the name server addresses because we never did it
  52      and it would be done implicitly on shutdown.  */
  53   __res_iclose (&_res, false);
  54 }