lib/sockets.c

   1 /* sockets.c --- wrappers for Windows socket functions
   2
   3    Copyright (C) 2008-2017 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 <http://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 # include "msvc-nothrow.h"
  32
  33 /* Get set_winsock_errno, FD_TO_SOCKET etc. */
  34 # include "w32sock.h"
  35
  36 static int
  37 close_fd_maybe_socket (const struct fd_hook *remaining_list,
  38                        gl_close_fn primary,
  39                        int fd)
  40 {
  41   /* Note about multithread-safety: There is a race condition where, between
  42      our calls to closesocket() and the primary close(), some other thread
  43      could make system calls that allocate precisely the same HANDLE value
  44      as sock; then the primary close() would call CloseHandle() on it.  */
  45   SOCKET sock;
  46   WSANETWORKEVENTS ev;
  47
  48   /* Test whether fd refers to a socket.  */
  49   sock = FD_TO_SOCKET (fd);
  50   ev.lNetworkEvents = 0xDEADBEEF;
  51   WSAEnumNetworkEvents (sock, NULL, &ev);
  52   if (ev.lNetworkEvents != 0xDEADBEEF)
  53     {
  54       /* fd refers to a socket.  */
  55       /* FIXME: other applications, like squid, use an undocumented
  56          _free_osfhnd free function.  But this is not enough: The 'osfile'
  57          flags for fd also needs to be cleared, but it is hard to access it.
  58          Instead, here we just close twice the file descriptor.  */
  59       if (closesocket (sock))
  60         {
  61           set_winsock_errno ();
  62           return -1;
  63         }
  64       else
  65         {
  66           /* This call frees the file descriptor and does a
  67              CloseHandle ((HANDLE) _get_osfhandle (fd)), which fails.  */
  68           _close (fd);
  69           return 0;
  70         }
  71     }
  72   else
  73     /* Some other type of file descriptor.  */
  74     return execute_close_hooks (remaining_list, primary, fd);
  75 }
  76
  77 static int
  78 ioctl_fd_maybe_socket (const struct fd_hook *remaining_list,
  79                        gl_ioctl_fn primary,
  80                        int fd, int request, void *arg)
  81 {
  82   SOCKET sock;
  83   WSANETWORKEVENTS ev;
  84
  85   /* Test whether fd refers to a socket.  */
  86   sock = FD_TO_SOCKET (fd);
  87   ev.lNetworkEvents = 0xDEADBEEF;
  88   WSAEnumNetworkEvents (sock, NULL, &ev);
  89   if (ev.lNetworkEvents != 0xDEADBEEF)
  90     {
  91       /* fd refers to a socket.  */
  92       if (ioctlsocket (sock, request, arg) < 0)
  93         {
  94           set_winsock_errno ();
  95           return -1;
  96         }
  97       else
  98         return 0;
  99     }
 100   else
 101     /* Some other type of file descriptor.  */
 102     return execute_ioctl_hooks (remaining_list, primary, fd, request, arg);
 103 }
 104
 105 static struct fd_hook fd_sockets_hook;
 106
 107 static int initialized_sockets_version /* = 0 */;
 108
 109 #endif /* WINDOWS_SOCKETS */
 110
 111 int
 112 gl_sockets_startup (int version _GL_UNUSED)
 113 {
 114 #if WINDOWS_SOCKETS
 115   if (version > initialized_sockets_version)
 116     {
 117       WSADATA data;
 118       int err;
 119
 120       err = WSAStartup (version, &data);
 121       if (err != 0)
 122         return 1;
 123
 124       if (data.wVersion != version)
 125         {
 126           WSACleanup ();
 127           return 2;
 128         }
 129
 130       if (initialized_sockets_version == 0)
 131         register_fd_hook (close_fd_maybe_socket, ioctl_fd_maybe_socket,
 132                           &fd_sockets_hook);
 133
 134       initialized_sockets_version = version;
 135     }
 136 #endif
 137
 138   return 0;
 139 }
 140
 141 int
 142 gl_sockets_cleanup (void)
 143 {
 144 #if WINDOWS_SOCKETS
 145   int err;
 146
 147   initialized_sockets_version = 0;
 148
 149   unregister_fd_hook (&fd_sockets_hook);
 150
 151   err = WSACleanup ();
 152   if (err != 0)
 153     return 1;
 154 #endif
 155
 156   return 0;
 157 }