/*

 * Copyright (c) 2010, Oracle America, Inc.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions are

 * met:

 *

 *     * Redistributions of source code must retain the above copyright

 *       notice, this list of conditions and the following disclaimer.

 *     * Redistributions in binary form must reproduce the above

 *       copyright notice, this list of conditions and the following

 *       disclaimer in the documentation and/or other materials

 *       provided with the distribution.

 *     * Neither the name of the "Oracle America, Inc." nor the names of its

 *       contributors may be used to endorse or promote products derived

 *       from this software without specific prior written permission.

 *

 *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS

 *   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT

 *   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS

 *   FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE

 *   COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,

 *   INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL

 *   DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE

 *   GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS

 *   INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,

 *   WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING

 *   NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE

 *   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 */

#include <errno.h>

#include <unistd.h>

#include <string.h>

#include <sys/types.h>

#include <sys/socket.h>

#include <netinet/in.h>

#include <libc-lock.h>

/*

 * Locks the static variables in this file.

 */

__libc_lock_define_initialized (static, lock);

/*

 * Bind a socket to a privileged IP port

 */

int

bindresvport (int sd, struct sockaddr_in *sin)

{

  static short port;

  struct sockaddr_in myaddr;

  int i;

#define STARTPORT 600

#define LOWPORT 512

#define ENDPORT (IPPORT_RESERVED - 1)

#define NPORTS	(ENDPORT - STARTPORT + 1)

  static short startport = STARTPORT;

  if (sin == (struct sockaddr_in *) 0)

    {

      sin = &myaddr;

      memset (sin, 0, sizeof (*sin));

      sin->sin_family = AF_INET;

    }

  else if (sin->sin_family != AF_INET)

    {

      __set_errno (EAFNOSUPPORT);

      return -1;

    }

  if (port == 0)

    {

      port = (__getpid () % NPORTS) + STARTPORT;

    }

  /* Initialize to make gcc happy.  */

  int res = -1;

  int nports = ENDPORT - startport + 1;

  int endport = ENDPORT;

  __libc_lock_lock (lock);

 again:

  for (i = 0; i < nports; ++i)

    {

      sin->sin_port = htons (port++);

      if (port > endport)

	port = startport;

      res = __bind (sd, sin, sizeof (struct sockaddr_in));

      if (res >= 0 || errno != EADDRINUSE)

	break;

    }

  if (i == nports && startport != LOWPORT)

    {

      startport = LOWPORT;

      endport = STARTPORT - 1;

      nports = STARTPORT - LOWPORT;

      port = LOWPORT + port % (STARTPORT - LOWPORT);

      goto again;

    }

  __libc_lock_unlock (lock);

  return res;

}

libc_hidden_def (bindresvport)