1  /* sockets.c --- wrappers for Windows socket functions
       2  
       3     Copyright (C) 2008-2023 Free Software Foundation, Inc.
       4  
       5     This file is free software: you can redistribute it and/or modify
       6     it under the terms of the GNU Lesser General Public License as
       7     published by the Free Software Foundation; either version 2.1 of the
       8     License, or (at your option) any later version.
       9  
      10     This file 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
      13     GNU Lesser General Public License for more details.
      14  
      15     You should have received a copy of the GNU Lesser General Public License
      16     along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
      17  
      18  /* Written by Simon Josefsson */
      19  
      20  #include <config.h>
      21  
      22  /* Specification.  */
      23  #include "sockets.h"
      24  
      25  #if WINDOWS_SOCKETS
      26  
      27  /* This includes winsock2.h on MinGW. */
      28  # include <sys/socket.h>
      29  
      30  # include "fd-hook.h"
      31  # if GNULIB_MSVC_NOTHROW
      32  #  include "msvc-nothrow.h"
      33  # else
      34  #  include <io.h>
      35  # endif
      36  
      37  /* Get set_winsock_errno, FD_TO_SOCKET etc. */
      38  # include "w32sock.h"
      39  
      40  static int
      41  close_fd_maybe_socket (const struct fd_hook *remaining_list,
      42                         gl_close_fn primary,
      43                         int fd)
      44  {
      45    /* Note about multithread-safety: There is a race condition where, between
      46       our calls to closesocket() and the primary close(), some other thread
      47       could make system calls that allocate precisely the same HANDLE value
      48       as sock; then the primary close() would call CloseHandle() on it.  */
      49    SOCKET sock;
      50    WSANETWORKEVENTS ev;
      51  
      52    /* Test whether fd refers to a socket.  */
      53    sock = FD_TO_SOCKET (fd);
      54    ev.lNetworkEvents = 0xDEADBEEF;
      55    WSAEnumNetworkEvents (sock, NULL, &ev);
      56    if (ev.lNetworkEvents != 0xDEADBEEF)
      57      {
      58        /* fd refers to a socket.  */
      59        /* FIXME: other applications, like squid, use an undocumented
      60           _free_osfhnd free function.  But this is not enough: The 'osfile'
      61           flags for fd also needs to be cleared, but it is hard to access it.
      62           Instead, here we just close twice the file descriptor.  */
      63        if (closesocket (sock))
      64          {
      65            set_winsock_errno ();
      66            return -1;
      67          }
      68        else
      69          {
      70            /* This call frees the file descriptor and does a
      71               CloseHandle ((HANDLE) _get_osfhandle (fd)), which fails.  */
      72            _close (fd);
      73            return 0;
      74          }
      75      }
      76    else
      77      /* Some other type of file descriptor.  */
      78      return execute_close_hooks (remaining_list, primary, fd);
      79  }
      80  
      81  static int
      82  ioctl_fd_maybe_socket (const struct fd_hook *remaining_list,
      83                         gl_ioctl_fn primary,
      84                         int fd, int request, void *arg)
      85  {
      86    SOCKET sock;
      87    WSANETWORKEVENTS ev;
      88  
      89    /* Test whether fd refers to a socket.  */
      90    sock = FD_TO_SOCKET (fd);
      91    ev.lNetworkEvents = 0xDEADBEEF;
      92    WSAEnumNetworkEvents (sock, NULL, &ev);
      93    if (ev.lNetworkEvents != 0xDEADBEEF)
      94      {
      95        /* fd refers to a socket.  */
      96        if (ioctlsocket (sock, request, arg) < 0)
      97          {
      98            set_winsock_errno ();
      99            return -1;
     100          }
     101        else
     102          return 0;
     103      }
     104    else
     105      /* Some other type of file descriptor.  */
     106      return execute_ioctl_hooks (remaining_list, primary, fd, request, arg);
     107  }
     108  
     109  static struct fd_hook fd_sockets_hook;
     110  
     111  static int initialized_sockets_version /* = 0 */;
     112  
     113  #endif /* WINDOWS_SOCKETS */
     114  
     115  int
     116  gl_sockets_startup (_GL_UNUSED int version)
     117  {
     118  #if WINDOWS_SOCKETS
     119    if (version > initialized_sockets_version)
     120      {
     121        WSADATA data;
     122        int err;
     123  
     124        err = WSAStartup (version, &data);
     125        if (err != 0)
     126          return 1;
     127  
     128        if (data.wVersion != version)
     129          {
     130            WSACleanup ();
     131            return 2;
     132          }
     133  
     134        if (initialized_sockets_version == 0)
     135          register_fd_hook (close_fd_maybe_socket, ioctl_fd_maybe_socket,
     136                            &fd_sockets_hook);
     137  
     138        initialized_sockets_version = version;
     139      }
     140  #endif
     141  
     142    return 0;
     143  }
     144  
     145  int
     146  gl_sockets_cleanup (void)
     147  {
     148  #if WINDOWS_SOCKETS
     149    int err;
     150  
     151    initialized_sockets_version = 0;
     152  
     153    unregister_fd_hook (&fd_sockets_hook);
     154  
     155    err = WSACleanup ();
     156    if (err != 0)
     157      return 1;
     158  #endif
     159  
     160    return 0;
     161  }