/* sockets.c --- wrappers for Windows socket functions

   Copyright (C) 2008-2020 Free Software Foundation, Inc.

   This program is free software: you can redistribute it and/or modify

   it under the terms of the GNU General Public License as published by

   the Free Software Foundation; either version 3 of the License, or

   (at your option) any later version.

   This program is distributed in the hope that it will be useful,

   but WITHOUT ANY WARRANTY; without even the implied warranty of

   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License

   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */

/* Written by Simon Josefsson */

#include <config.h>

/* Specification.  */

#include "sockets.h"

#if WINDOWS_SOCKETS

/* This includes winsock2.h on MinGW. */

# include <sys/socket.h>

# include "fd-hook.h"

# if GNULIB_MSVC_NOTHROW

#  include "msvc-nothrow.h"

# else

#  include <io.h>

# endif

/* Get set_winsock_errno, FD_TO_SOCKET etc. */

# include "w32sock.h"

static int

close_fd_maybe_socket (const struct fd_hook *remaining_list,

                       gl_close_fn primary,

                       int fd)

{

  /* Note about multithread-safety: There is a race condition where, between

     our calls to closesocket() and the primary close(), some other thread

     could make system calls that allocate precisely the same HANDLE value

     as sock; then the primary close() would call CloseHandle() on it.  */

  SOCKET sock;

  WSANETWORKEVENTS ev;

  /* Test whether fd refers to a socket.  */

  sock = FD_TO_SOCKET (fd);

  ev.lNetworkEvents = 0xDEADBEEF;

  WSAEnumNetworkEvents (sock, NULL, &ev;;

  if (ev.lNetworkEvents != 0xDEADBEEF)

    {

      /* fd refers to a socket.  */

      /* FIXME: other applications, like squid, use an undocumented

         _free_osfhnd free function.  But this is not enough: The 'osfile'

         flags for fd also needs to be cleared, but it is hard to access it.

         Instead, here we just close twice the file descriptor.  */

      if (closesocket (sock))

        {

          set_winsock_errno ();

          return -1;

        }

      else

        {

          /* This call frees the file descriptor and does a

             CloseHandle ((HANDLE) _get_osfhandle (fd)), which fails.  */

          _close (fd);

          return 0;

        }

    }

  else

    /* Some other type of file descriptor.  */

    return execute_close_hooks (remaining_list, primary, fd);

}

static int

ioctl_fd_maybe_socket (const struct fd_hook *remaining_list,

                       gl_ioctl_fn primary,

                       int fd, int request, void *arg)

{

  SOCKET sock;

  WSANETWORKEVENTS ev;

  /* Test whether fd refers to a socket.  */

  sock = FD_TO_SOCKET (fd);

  ev.lNetworkEvents = 0xDEADBEEF;

  WSAEnumNetworkEvents (sock, NULL, &ev;;

  if (ev.lNetworkEvents != 0xDEADBEEF)

    {

      /* fd refers to a socket.  */

      if (ioctlsocket (sock, request, arg) < 0)

        {

          set_winsock_errno ();

          return -1;

        }

      else

        return 0;

    }

  else

    /* Some other type of file descriptor.  */

    return execute_ioctl_hooks (remaining_list, primary, fd, request, arg);

}

static struct fd_hook fd_sockets_hook;

static int initialized_sockets_version /* = 0 */;

#endif /* WINDOWS_SOCKETS */

int

gl_sockets_startup (int version _GL_UNUSED)

{

#if WINDOWS_SOCKETS

  if (version > initialized_sockets_version)

    {

      WSADATA data;

      int err;

      err = WSAStartup (version, &data);

      if (err != 0)

        return 1;

      if (data.wVersion != version)

        {

          WSACleanup ();

          return 2;

        }

      if (initialized_sockets_version == 0)

        register_fd_hook (close_fd_maybe_socket, ioctl_fd_maybe_socket,

                          &fd_sockets_hook);

      initialized_sockets_version = version;

    }

#endif

  return 0;

}

int

gl_sockets_cleanup (void)

{

#if WINDOWS_SOCKETS

  int err;

  initialized_sockets_version = 0;

  unregister_fd_hook (&fd_sockets_hook);

  err = WSACleanup ();

  if (err != 0)

    return 1;

#endif

  return 0;

}