Open socket for communication with network layer.

1 files changed, 111 insertions, 0 deletions

diff --git a/sysdeps/unix/sysv/linux/opensock.c b/sysdeps/unix/sysv/linux/opensock.c
new file mode 100644
index 0000000000..a3c55a94e8
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/opensock.c
@@ -0,0 +1,111 @@
+/* Copyright (C) 1999, 2001 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library 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
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, write to the Free
+   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+   02111-1307 USA.  */
+
+#include <assert.h>
+#include <errno.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <sys/socket.h>
+
+/* Return a socket of any type.  The socket can be used in subsequent
+   ioctl calls to talk to the kernel.  */
+int internal_function
+__opensock (void)
+{
+  static int last_family;	/* Available socket family we will use.  */
+  static int last_type;
+  static const struct
+  {
+    int family;
+    const char procname[15];
+  } afs[] =
+    {
+      { AF_UNIX, "net/unix" },
+      { AF_INET, "" },
+      { AF_INET6, "net/if_inet6" },
+      { AF_AX25, "net/ax25" },
+      { AF_NETROM, "net/nr" },
+      { AF_ROSE, "net/rose" },
+      { AF_IPX, "net/ipx" },
+      { AF_APPLETALK, "net/appletalk" },
+      { AF_ECONET, "sys/net/econet" },
+      { AF_ASH, "sys/net/ash" },
+      { AF_X25, "net/x25" }
+    };
+#define nafs (sizeof (afs) / sizeof (afs[0]))
+  char fname[sizeof "/proc/" + 14];
+  int result;
+  int has_proc;
+  int cnt;
+
+  /* We already know which family to use from the last call.  Use it
+     again.  */
+  if (last_family != 0)
+    {
+      assert (last_type != 0);
+
+      result = socket (last_family, last_type, 0);
+      if (result != -1 || errno != EAFNOSUPPORT)
+	/* Maybe the socket type isn't supported anymore (module is
+	   unloaded).  In this case again try to find the type.  */
+	return result;
+
+      /* Reset the values.  They seem not valid anymore.  */
+      last_family = 0;
+      last_type = 0;
+    }
+
+  /* Check whether the /proc filesystem is available.  */
+  has_proc = __access ("/proc/net", R_OK) != -1;
+  strcpy (fname, "/proc/");
+
+  /* Iterate over the interface families and find one which is
+     available.  */
+  for (cnt = 0; cnt < nafs; ++cnt)
+    {
+      int type = SOCK_DGRAM;
+
+      if (has_proc && afs[cnt].procname[0] != '\0')
+	{
+	  strcpy (fname + 6, afs[cnt].procname);
+	  if (__access (fname, R_OK) == -1)
+	    /* The /proc entry is not available.  I.e., we cannot
+	       create a socket of this type (without loading the
+	       module).  Don't look for it since this might trigger
+	       loading the module.  */
+	    continue;
+	}
+
+      if (afs[cnt].family == AF_NETROM || afs[cnt].family == AF_X25)
+	type = SOCK_SEQPACKET;
+
+      result = socket (afs[cnt].family, type, 0);
+      if (result != -1)
+	{
+	  /* Found an available family.  */
+	  last_type = type;
+	  last_family = afs[cnt].family;
+	  return result;
+	}
+    }
+
+  /* None of the protocol families is available.  It is unclear what kind
+     of error is returned.  ENOENT seems like a reasonable choice.  */
+  __set_errno (ENOENT);
+  return -1;
+}