1 files changed, 74 insertions, 0 deletions
diff --git a/proto.c b/proto.c
new file mode 100644
index 0000000..df5b77b
--- /dev/null
+++ b/proto.c
@@ -0,0 +1,74 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2005 OpenVPN Solutions LLC <info@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  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 (see the file COPYING included with this
+ *  distribution); if not, write to the Free Software Foundation, Inc.,
+ *  59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#ifdef WIN32
+#include "config-win32.h"
+#else
+#include "config.h"
+#endif
+
+#include "syshead.h"
+
+#include "proto.h"
+
+#include "memdbg.h"
+
+/*
+ * If raw tunnel packet is IPv4, return true and increment
+ * buffer offset to start of IP header.
+ */
+bool
+is_ipv4 (int tunnel_type, struct buffer *buf)
+{
+  int offset;
+  const struct openvpn_iphdr *ih;
+
+  verify_align_4 (buf);
+  if (tunnel_type == DEV_TYPE_TUN)
+    {
+      if (BLEN (buf) < (int) sizeof (struct openvpn_iphdr))
+	return false;
+      offset = 0;
+    }
+  else if (tunnel_type == DEV_TYPE_TAP)
+    {
+      const struct openvpn_ethhdr *eh;
+      if (BLEN (buf) < (int)(sizeof (struct openvpn_ethhdr)
+	  + sizeof (struct openvpn_iphdr)))
+	return false;
+      eh = (const struct openvpn_ethhdr *) BPTR (buf);
+      if (ntohs (eh->proto) != OPENVPN_ETH_P_IPV4)
+	return false;
+      offset = sizeof (struct openvpn_ethhdr);
+    }
+  else
+    return false;
+
+  ih = (const struct openvpn_iphdr *) (BPTR (buf) + offset);
+
+  if (OPENVPN_IPH_GET_VER (ih->version_len) == 4)
+    return buf_advance (buf, offset);
+  else
+    return false;
+}