lib/sockets.c

   1 /* sockets.c --- wrappers for Windows socket functions
   2
   3    Copyright (C) 2008-2020 Free Software Foundation, Inc.
   4
   5    This program is free software: you can redistribute it and/or modify
   6    it under the terms of the GNU General Public License as published by
   7    the Free Software Foundation; either version 3 of the License, or
   8    (at your option) any later version.
   9
  10    This program 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 General Public License for more details.
  14
  15    You should have received a copy of the GNU 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 (int version _GL_UNUSED)
 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 }