glibc/resolv/res_libc.c

/*
 * Copyright (c) 1995-1999 by Internet Software Consortium.
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
 * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
 * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
 * SOFTWARE.
 */

/* Define some functions that go int libc.so.  */

#if defined(LIBC_SCCS) && !defined(lint)
static const char rcsid[] = "$Id$";
#endif /* LIBC_SCCS and not lint */

#include <sys/types.h>
#include <sys/param.h>
#include <sys/socket.h>
#include <sys/time.h>

#include <netinet/in.h>
#include <arpa/inet.h>
#include <arpa/nameser.h>

#include <ctype.h>
#include <netdb.h>
#include <resolv.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>


/* This is the old res_init function.  It has been moved from
   res_data.c to this file since res_init should go into libc.so but
   the rest of res_data not.  */


int
res_init(void) {
	extern int __res_vinit(res_state, int);

	/*
	 * These three fields used to be statically initialized.  This made
	 * it hard to use this code in a shared library.  It is necessary,
	 * now that we're doing dynamic initialization here, that we preserve
	 * the old semantics: if an application modifies one of these three
	 * fields of _res before res_init() is called, res_init() will not
	 * alter them.  Of course, if an application is setting them to
	 * _zero_ before calling res_init(), hoping to override what used
	 * to be the static default, we can't detect it and unexpected results
	 * will follow.  Zero for any of these fields would make no sense,
	 * so one can safely assume that the applications were already getting
	 * unexpected results.
	 *
	 * _res.options is tricky since some apps were known to diddle the bits
	 * before res_init() was first called. We can't replicate that semantic
	 * with dynamic initialization (they may have turned bits off that are
	 * set in RES_DEFAULT).  Our solution is to declare such applications
	 * "broken".  They could fool us by setting RES_INIT but none do (yet).
	 */
	if (!_res.retrans)
		_res.retrans = RES_TIMEOUT;
	if (!_res.retry)
		_res.retry = 4;
	if (!(_res.options & RES_INIT))
		_res.options = RES_DEFAULT;

	/*
	 * This one used to initialize implicitly to zero, so unless the app
	 * has set it to something in particular, we can randomize it now.
	 */
	if (!_res.id)
		_res.id = res_randomid();

	return (__res_vinit(&_res, 1));
}

/* We need a resolver context - in unthreaded apps, this weak function
   provides it.  */

#undef _res

struct __res_state _res;


struct __res_state *
weak_const_function
__res_state(void)
{
  return &_res;
}