Problem with Sockets

Visual C# General

Peter Doss

Hi buddies, How are you !!

I got the following problem while i am developing a chat software

My software consists of two parts:

  • Server
  • Client

each in a seperate project, and each works very well when they are working alone, but when i try to test my application -I run the server then the client- i got the problem that when the client create the TcpClient object i got this message:

Only one usage of each socket address (protocol/network address/port) is normally permitted

I think that is because i use the same port number for both applications but this is the only way to run both applications on the same machine.

the short version of my question is:

How can I start a TcpListener and a TcpClient on the same machine and the same port

I tried all the windows registry things but no change accured,

Thanks in advance.

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Re: Visual C# General Problem with Sockets

timvw

To me it seems that both your server and client are trying to bind to the same ip:port combination... Only the server should bind to a socket.. And the client should then connect/open (but not bind to) that socket...




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Re: Visual C# General Problem with Sockets

Peter Doss

Hi Timvw,

yes my server binds the ip/port, and my client use a TcpClient to connect to the server, i think this is the normal way to do it, is there any way to connect to the server without using the TcpClient bound to the port





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Re: Visual C# General Problem with Sockets

timvw

Could you show us the code please

server:

IPAddress ipAddress = IPAddress.Parse("127.0.0.1");
int port = 54321;

TcpListener tcpListener = new TcpListener(ipAddress, port);

// start, acceptsockets, close, ...


client:

TcpClient tcpClient = new TcpClient();
tcpClient.Connect("127.0.0.1", 54321);

// read, write, close, ...






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Re: Visual C# General Problem with Sockets

Thomas Li

Hi Peter

I just tested this:

Server:

TcpListener tcpl = new TcpListener(IPAddress.Any, 101);

public Form1()
{
InitializeComponent();
}

private void Form1_Load(object sender, EventArgs e)
{
tcpl.Start();
tcpl.AcceptTcpClient();
}

Client:

TcpClient tc = new TcpClient("localhost", 101);
bool x = tc.Connected;

x became true (no error or something else)

Could it be that you have 2 server instances running or that some other application is already running on that specific port (skype always listens at port 80 for example)


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Re: Visual C# General Problem with Sockets

Peter Doss

Hi Tim, Hi Thomas

My server code is something like this:

 

this.listener = new TcpListener(IPAddress.Loopback, 12554);

this.listener.Start();

while (true)

{

try

{

this.socket = this.listener.AcceptSocket();

this.stream = new NetworkStream(this.socket);

this.reader = new BinaryReader(this.stream);

this.writer = new BinaryWriter(this.stream);

if (this.Authenticate())

this.Redirect();

}

catch { }

}

 

 

and it run in a seperate thread

my client code is:

System.Net.IPEndPoint ee = new System.Net.IPEndPoint(System.Net.IPAddress.Loopback, 12554);

TcpClient cl = new TcpClient(endPoint);

try

{

this.stream = cl.GetStream();

this.reader = new BinaryReader(this.stream);

this.writer = new BinaryWriter(this.stream);

}

catch

{ }

 

 

I am sure the problem is not because another application is using this ip/port, because the exception doesn't happen when i don't start the server

When i compiled the code with .NetFX 1.1(VS 2003) the problem didn't accur

 



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Re: Visual C# General Problem with Sockets

timvw

If you use the TcpClient constructor that accepts an IPEndPoint you will bind to that address...


The following code should do what you want:

TcpClient cl = new TcpClient();
cl.Connect(endPoint);




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Re: Visual C# General Problem with Sockets

Peter Doss

When i used the Connect method, the old exception didn't happen but a new one happens that says that the target machine refuses the connection, i checked my network configuration and my firewall setting and still got the same message

if you have evered experienced that please help me, thank you :)





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Re: Visual C# General Problem with Sockets

timvw

If you're sure your firewall(s) and network configuration are accepting incoming connections on that ip:port than you should verifiy if the server is really running ;)

(netstat -an might be helpful)




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