source/Cosmos/Cosmos.System/Cosmos.Sys.csproj

@@ -49,6 +49,7 @@
     <Compile Include="Boot.cs" />
     <Compile Include="Deboot.cs" />
     <Compile Include="Global.cs" />
+    <Compile Include="Network\IP4Packet.cs" />
     <Compile Include="Network\Packet.cs" />
     <Compile Include="Network\UDPPacket.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />

source/Cosmos/Cosmos.System/Network/IP4Packet.cs

@@ -0,0 +1,16 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+
+namespace Cosmos.Sys.Network {
+    public abstract class IP4Packet : Packet {
+        protected int mHeaderSize = 20;
+        protected int mHeaderBegin;
+
+        protected override int Initialize(byte[] aData, int aHeaderSize) {
+           mHeaderBegin = base.Initialize(aData, mHeaderSize + aHeaderSize);
+           return mHeaderBegin;
+        }
+    }
+}

source/Cosmos/Cosmos.System/Network/Packet.cs

@@ -11,16 +11,17 @@ namespace Cosmos.Sys.Network {
         // user that it is not a direct access, but incurs a performance
         // penalty to call
         public byte[] GetData() {
-            Finalize();
+            Conclude();
             return mData;
         }
 
-        protected void Initialize(byte[] aData, int aHeaderSize) {
+        protected virtual int Initialize(byte[] aData, int aHeaderSize) {
             mData = new byte[aData.Length + 8];
             aData.CopyTo(mData, 8);
+            return 0;
         }
 
-        protected virtual void Finalize() {
+        protected virtual void Conclude() {
         }
     }
 }

source/Cosmos/Cosmos.System/Network/UDPPacket.cs

@@ -5,26 +5,28 @@ using System.Text;
 
 namespace Cosmos.Sys.Network {
     // http://en.wikipedia.org/wiki/User_Datagram_Protocol
-    public class UDPPacket : Packet {
+    public class UDPPacket : IP4Packet {
         public UDPPacket(int aSrcPort, int aDestPort, byte[] aData) {
-            Initialize(aData, 8);
+            mHeaderBegin = Initialize(aData, 8);
             // Source Port
-            mData[0] = (byte)(aSrcPort >> 8);
-            mData[1] = (byte)(aSrcPort & 0xFF);
+            mData[mHeaderBegin] = (byte)(aSrcPort >> 8);
+            mData[mHeaderBegin + 1] = (byte)(aSrcPort & 0xFF);
             // Destination Port
-            mData[2] = (byte)(aDestPort >> 8);
-            mData[3] = (byte)(aDestPort & 0xFF);
+            mData[mHeaderBegin + 2] = (byte)(aDestPort >> 8);
+            mData[mHeaderBegin + 3] = (byte)(aDestPort & 0xFF);
             // Length
-            mData[4] = (byte)(mData.Length >> 8);
-            mData[5] = (byte)(mData.Length & 0xFF);
+            mData[mHeaderBegin + 4] = (byte)(mData.Length >> 8);
+            mData[mHeaderBegin + 5] = (byte)(mData.Length & 0xFF);
         }
 
-        protected override void Finalize() {
-            base.Finalize();
+        protected new int mHeaderBegin = 0;
+
+        protected override void Conclude() {
+            base.Conclude();
             // Checksum
             //TODO: Uses info from IPHeader to create check sum as well
-            mData[6] = 0;
-            mData[7] = 0;
+            mData[mHeaderBegin + 6] = 0;
+            mData[mHeaderBegin + 7] = 0;
         }
     }
 }