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Need help with C# and networking


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#1 SW214   Members   -  Reputation: 118

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Posted 28 September 2012 - 02:02 AM

So I've been trying to learn networking with a simple "game" using XNA and having it work over a network. Basically it's two dots that are supposed to move with WASD and there's a server they connect to. When it's connecting to localhost it's working fine but if I try to use it when it's not on the same machine I run into problems and things end up crashing and I'm just not sure why.

I've added the code to both below. It may be a little messy because I've been trying anything I could possibly thing of to get it to work. Here's the full code for both the server and the client.

Server:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Microsoft.Xna.Framework;
using System.Net.Sockets;
using System.Net;
using System.IO;
using System.Threading;
using System.Runtime.Serialization;
using System.Runtime.Serialization.Formatters.Binary;
namespace GameServer
{
	class SocketClass
	{
		public Socket accepted;
		public Vector2 position;
		Vector2 lastPos;
		public int id;
		public SocketClass(Socket sock, int num)
		{
			accepted = sock;
			position = Vector2.Zero;
			lastPos = Vector2.Zero;
			id = num;
		}
		public void recData()
		{
			Thread receiveThread = new Thread(() =>
			{
				while (true)
				{
					try
					{
						byte[] buffer = new byte[500];
						int size = accepted.Receive(buffer);
						Array.Resize(ref buffer, size);
						MemoryStream ms = new MemoryStream(buffer);
						BinaryFormatter bf = new BinaryFormatter();
						lastPos = position;
						position = (Vector2)bf.Deserialize(ms);
						Console.Write(id + ": " + "X: " + position.X + " Y: " + position.Y + "\r\n");
					}
					catch
					{
					}
				}
			});
			receiveThread.Start();
		}

		public bool positionChanged()
		{
			if (lastPos == position)
			{
				return false;
			}
			else
				return true;
		}
		public Vector2 getPos()
		{
			return position;
		}
	}
	class Program
	{
		static void Main(string[] args)
		{
			int nextId = 0;
			Socket sock = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
			List<SocketClass> incoming = new List<SocketClass>();
			sock.Bind(new IPEndPoint(0, 1234));
			sock.Listen(0);
			Thread accept = new Thread(() =>
			{
				while (true)
				{
					incoming.Add(new SocketClass(sock.Accept(), nextId));
					Console.Write("Connected\r\n");
					try
					{
						incoming[nextId].recData();
					}
					catch
					{
					}
					nextId++;
				}
			});
			accept.Start();
			while (true)
			{
				for(int i = 0; i < incoming.Count; i++)
				{
					if (incoming[i].positionChanged())
					{
						for (int j = 0; j < incoming.Count; j++)
						{
							if (incoming[i].id != j)
							{
								try
								{
									MemoryStream ms = new MemoryStream();
									BinaryFormatter bf = new BinaryFormatter();
									bf.Serialize(ms, incoming[i].position);
									incoming[j].accepted.Send(ms.ToArray());
								}
								catch
								{
								}
							}
						}
					}
				}
			}
			Console.Read();
		}
	}
}

And here's what I'm using for the client:

using System;
using System.Collections.Generic;
using System.Linq;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Audio;
using Microsoft.Xna.Framework.Content;
using Microsoft.Xna.Framework.GamerServices;
using Microsoft.Xna.Framework.Graphics;
using Microsoft.Xna.Framework.Input;
using Microsoft.Xna.Framework.Media;
using System.Net.Sockets;
using System.Net;
using System.IO;
using System.Threading;
using System.Runtime.Serialization;
using System.Runtime.Serialization.Formatters.Binary;
namespace TestGame
{
	/// <summary>
	/// This is the main type for your game
	/// </summary>
	public class Game1 : Microsoft.Xna.Framework.Game
	{
		GraphicsDeviceManager graphics;
		SpriteBatch spriteBatch;
		Socket sock;
		Texture2D ball, otherBall;
		Vector2 otherVector;
		Vector2 position;
		Vector2 lastPos;
		Thread sockThread;
		int connectedPeople;
		public Game1()
		{
			graphics = new GraphicsDeviceManager(this);
			Content.RootDirectory = "Content";
		}
		/// <summary>
		/// Allows the game to perform any initialization it needs to before starting to run.
		/// This is where it can query for any required services and load any non-graphic
		/// related content.  Calling base.Initialize will enumerate through any components
		/// and initialize them as well.
		/// </summary>
		protected override void Initialize()
		{
			// TODO: Add your initialization logic here
			position = new Vector2(50, 50);
			lastPos = Vector2.Zero;
			sock = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
			base.Initialize();
		}
		/// <summary>
		/// LoadContent will be called once per game and is the place to load
		/// all of your content.
		/// </summary>
		protected override void LoadContent()
		{
			// Create a new SpriteBatch, which can be used to draw textures.
			spriteBatch = new SpriteBatch(GraphicsDevice);
			// TODO: use this.Content to load your game content here
			ball = Content.Load<Texture2D>("testpic");
			otherBall = Content.Load<Texture2D>("othertest");
		  
			try
			{
				sock.Connect("127.0.0.1", 1234);
				BinaryFormatter bf = new BinaryFormatter();
				sockThread = new Thread(() =>
				{
					byte[] buffer = new byte[900];
					while (true)
					{
						int size = sock.Receive(buffer);
						connectedPeople = 1;
						Array.Resize(ref buffer, size);
						MemoryStream ms = new MemoryStream(buffer);
						try
						{
							otherVector = (Vector2)bf.Deserialize(ms);
						}
						catch
						{
						}
					}
				});
				sockThread.Start();
			}
			catch
			{
			}
		  
		}
		/// <summary>
		/// UnloadContent will be called once per game and is the place to unload
		/// all content.
		/// </summary>
		protected override void UnloadContent()
		{
			// TODO: Unload any non ContentManager content here
		}
		/// <summary>
		/// Allows the game to run logic such as updating the world,
		/// checking for collisions, gathering input, and playing audio.
		/// </summary>
		/// <param name="gameTime">Provides a snapshot of timing values.</param>
		protected override void Update(GameTime gameTime)
		{
			// Allows the game to exit
			if (GamePad.GetState(PlayerIndex.One).Buttons.Back == ButtonState.Pressed)
				this.Exit();
			// TODO: Add your update logic here
			KeyboardState keystate = Keyboard.GetState();
		  
			if(keystate.IsKeyDown(Keys.A))
			{
				position.X -= 1;
			}
			if (keystate.IsKeyDown(Keys.D))
			{
				position.X += 1;
			}
			if (keystate.IsKeyDown(Keys.W))
			{
				position.Y -= 1;
			}
			if (keystate.IsKeyDown(Keys.S))
			{
				position.Y += 1;
			}
			if (lastPos != position)
			{
				MemoryStream ms = new MemoryStream();
				BinaryFormatter bf = new BinaryFormatter();
				bf.Serialize(ms, position);
				byte[] buffer = ms.ToArray();
				sock.Send(buffer);
			}
			lastPos = position;
		  
			base.Update(gameTime);
		}
		/// <summary>
		/// This is called when the game should draw itself.
		/// </summary>
		/// <param name="gameTime">Provides a snapshot of timing values.</param>
		protected override void Draw(GameTime gameTime)
		{
			GraphicsDevice.Clear(Color.CornflowerBlue);
			// TODO: Add your drawing code here
			spriteBatch.Begin();
			spriteBatch.Draw(ball, position, Color.White);
			if (connectedPeople >= 1)
			{
				spriteBatch.Draw(otherBall, otherVector, Color.White);
			}
			spriteBatch.End();
			base.Draw(gameTime);
		}
	}
}


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#2 Xanather   Members   -  Reputation: 703

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Posted 28 September 2012 - 04:50 AM

This may be due to the way TCP works. TCP acts acts as a stream protocol. You may send data in this format (using two write commands, separated by the quotes): "hello" "my name is xanather" and they may be received on the other machine as "hel" "lo" "my name is xan" "ather". You need to be able to handle this, and there are many techniques in order to do so (using fixed-message lengths, prefix with message length etc...).

#3 hplus0603   Moderators   -  Reputation: 4907

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Posted 28 September 2012 - 01:11 PM

Three things:

1) Xanather is right: You do no formatting of the TCP stream, so you can't tell the difference between the end of one packet and the beginning of the next. There's suggestions in the FAQ for how to deal with this. (hint: send a length before each packet, and make sure there's enough data to decode the length before trying)

2) You're using the built-in system serialization support. It is possible to make that be compact and efficient, but if you use it for any kind of complex data structure, you will waste a lot of bandwidth, because it's designed for enterprise use cases, not game use cases.

3) You're using "Pokemon Exception Handling" ("Gotta catch them all!") Also known as "Enterprise Exception Handling," it's a terrible idea to catch all exceptions, and also to not do anything about them. You should get out of that habit ASAP, or it will bite you in the future!

enum Bool { True, False, FileNotFound };

#4 SW214   Members   -  Reputation: 118

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Posted 28 September 2012 - 03:35 PM

Ah, well that makes sense. That's what I get for trying to go off a simple tutorial to send a string and adjust it to work with what I want. I've just ordered a book about networking in C# so hopefully that will give me a better understanding of everything.

Thanks for the help, and the recommendations on my code. I actually never knew that about the built in serialization although I did know my catching all exceptions was horrible. I do appreciate it.

#5 James Proctor   Members   -  Reputation: 116

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Posted 30 September 2012 - 05:26 AM

Why not just use a prebuilt Network Library like Lidgren which is programmed in C# instead of trying to reinvent the wheel so to speak?




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