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Posted 21 Dec 2005

Genesis UDP Server and Client

, 21 Dec 2005
An article that shows the implementation of a lightweight UDP server and client with optional reliable channel.
 * Genesis Socket Server and Client
 * (C)Copyright 2005/2006 Robert Harwood <>
 * Please see included license.txt file for information on redistribution and usage.
#region Using directives

using System;
using System.Text;


namespace GenesisCore
	/// <summary>
	/// Enumeration containing filter flags for the broadcast methods.
	/// </summary>
	public enum BroadcastFilter : int
		None		= 0,					//Filter out everything
		Servers		= 1,					//Send to servers we are connected to.
		Clients		= 2,					//Send to clients connected to us.
		All			= Servers | Clients,	//Send to both servers and clients (every connection).
		AuthedOnly	= 4,					//Only send to authed clients or servers we are authed with.

    public class GenesisConsts
        //Command packet handling constants
        public static int MAX_EXCEPTIONS = 10;				//Maximum concurrent exceptions in receive loop before it shuts down
        public static int MAX_COMMAND_LEN = 512;			//Maimum command packet length (larger are split up)
        public static int MAX_FIELD_LEN = 2000;				//Maximum field length in a command
        public static int MAX_FIELDS = 50;					//Max number of fields allowed in a command
        public static int CONNECTION_TIMEOUT = 15;			//Seconds between pings before a connection is deemed timed out
        public static int CONNECTION_CLEAN_TIME = 3;		//Seconds between timed out connection cleanups
        public static int CONNECTION_PING_DELAY = 5;		//Seconds between pinging server connections
        public static int CONNECTION_RELIABLE_RETRY = 2;	//Seconds between resending reliable packets
		public static int CONNECTION_TIMEOUT_CHECK = 2;
		public static int CONNECTION_TIMEOUT_TIME = 5;
		public static int BAN_CHECK_TIME = 20;				//Seconds between checks of expired bans.
		public static int DEFAULT_MAX_WARNINGS = 3;			//Number of warnings an IP can get before being banned.
		public static int MAX_RELIABLE_QUEUED = 25;			//Maximum number of reliable commands that can be queued.

        //Used to ensure the encryption key was ok.
        public static string ENCRYPT_CHECK_STRING = "GC"; //Sent with every packet to validate the encryption key

        //Internal standard command opcodes
        public static string OPCODE_COMPOUNDPIECE = "00";
        public static string OPCODE_CONNECTIONREQUEST = "01";
        public static string OPCODE_CONNECTIONACK = "02";
        public static string OPCODE_LOGINDETAILS = "03";
        public static string OPCODE_LOGINACK = "04";
        public static string OPCODE_DISCONNECT = "05";
        public static string OPCODE_PING = "06";
        public static string OPCODE_RELIABLEACK = "07";

        //Command packet flags
        public static byte FLAGS_NONE = 0;
        public static byte FLAGS_CONNECTIONLESS = 1;
        public static byte FLAGS_ENCRYPTED = 2;
        public static byte FLAGS_COMPOUNDPIECE = 4;
        public static byte FLAGS_COMPOUNDEND = 8;
        public static byte FLAGS_RELIABLE = 16;
        public static byte FLAGS_SEQUENCED = 32;

        //Function return constants
        public static int UDP_OK = 0;
        public static int UDP_FAIL = 1000;
        public static int UDP_NOTFOUND = 1001;
        public static int UDP_ALREADYCONNECTED = 1002;
        public static int UDP_ALREADYINQUEUE = 1003;
        public static int UDP_UNRELIABLETOOLONG = 1004;
        public static int UDP_RELIABLENODESTINATION = 1005;
		public static int UDP_UNABLETORESOLVE = 1006;
		public static int UDP_RELIABLEQUEUEFULL = 1007;

        //UDP engine states
        public static int UDP_STATE_IDLE = 0;
        public static int UDP_STATE_LISTENING = 1;
        public static int UDP_STATE_CLOSING = 2;

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About the Author

Rob Harwood
Web Developer
United Kingdom United Kingdom
Born in England, I have been programming since a very early age when my dad gave me prewritten programs to type in and run on a Sinclair ZX81 machine (seeing my name printed out on a TV screen was enough to keep me entertained!). I later did work using basic and STOS basic on the Atari ST and after that got my first PC and used Microsoft's QBasic. Later when I was about 13 I was in an airport and saw a trial copy of Visual Basic on a magazine, which I bought and it got me hooked on the Microsoft development tools.

Currently I am studying a software engineering degree and have been working with .NET since 1.0. I have just moved over to Visual Studio 2005/.NET 2.0 and am loving it! During my degree I have worked for a year at DuPont, where I ended up changing a lot of their old existing software over to .NET and improving it in the process! Since then I have been back and done some consulting work involving maintaining some of their older C++/MFC software.

While most of my current interestes involve .NET I am also confident in working with C++ in Win32, VB, Java, and have even done some development work on the Linux platform (although most of this involved ensuring that software I wrote in C++ was platform independent).

I have a strong passion for software technology, both higher level and more recently, systems level stuff (the dissertation I am doing for my degree is to implement a small compiler and virtual machine in C# for a Pascal-style language).

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