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

[pbd22]

Hi. I am getting the below error:
Event Type: Error
Event Source: PeskyService
Event Category: None
Event ID: 0
Date: 1/30/2008
Time: 5:49:10 PM
User: N/A
Computer: Computer
Description:
Only one usage of each socket address (protocol/network address/port)
is normally permitted
The service is starting (successfully) and then throwing this error
immediately after. It does this about 1,900 times in a very short
period of time and then throws an event log too full error.

I am not closing something when I should be - I feel. I have provided
the relevant methods (I think) showing where stuff gets opened and
closed.

The methods are:

protected override void OnStart(string[] args)
{
this.timer1.Enabled = true;
new Thread(new ThreadStart(Listen)).Start();

}

protected override void OnStop()
{
this.timer1.Enabled = false;
base.OnStop();

}
public void Listen()
{

Queue unsyncq = new Queue();
connectionQueue = Queue.Synchronized(unsyncq);

try
{

TcpListener listener = new TcpListener(_telnetServer,
_telnetPort);
listener.Start();

while (true)
{

_telnetSocket = listener.AcceptTcpClient();
connectionQueue.Enqueue(_telnetSocket);

Thread workingthread = new Thread(new
ThreadStart(TheConnectionHandler));
workingthread.Start();

}

}
catch (Exception e)
{
eventLog2.WriteEntry("Error in Listener:" + e.Message,
EventLogEntryType.Error);
return;
}

}

....
public void TheConnectionHandler()
{

_telnetSocket = (TcpClient)connectionQueue.Dequeue();
_clientStream = _telnetSocket.GetStream();

while (true)
{

_bytesRead = 0;

try
{

_bytesRead = _clientStream.Read(message, 0,
4096); //message

}
catch
{
//a socket error has occured
break;
}
if (_bytesRead == 0)
{
break;
}

statusMessage += ASCII.GetString(message, 0,
_bytesRead);

[SNIP]

_telnetSocket.Close();
_clientStream.Close();
}

[=?Utf-8?B?QW5pbCBURw==?=]

This normally happens when a client tries to connect on a socket on which
another connection has already been accepted...

"pbd22" wrote:

>
Hi. I am getting the below error:
Event Type: Error
Event Source: PeskyService
Event Category: None
Event ID: 0
Date: 1/30/2008
Time: 5:49:10 PM
User: N/A
Computer: Computer
Description:
Only one usage of each socket address (protocol/network address/port)
is normally permitted
The service is starting (successfully) and then throwing this error
immediately after. It does this about 1,900 times in a very short
period of time and then throws an event log too full error.

I am not closing something when I should be - I feel. I have provided
the relevant methods (I think) showing where stuff gets opened and
closed.

The methods are:

protected override void OnStart(string[] args)
{
this.timer1.Enabled = true;
new Thread(new ThreadStart(Listen)).Start();

}

protected override void OnStop()
{
this.timer1.Enabled = false;
base.OnStop();

}
public void Listen()
{

Queue unsyncq = new Queue();
connectionQueue = Queue.Synchronized(unsyncq);

try
{

TcpListener listener = new TcpListener(_telnetServer,
_telnetPort);
listener.Start();

while (true)
{

_telnetSocket = listener.AcceptTcpClient();
connectionQueue.Enqueue(_telnetSocket);

Thread workingthread = new Thread(new
ThreadStart(TheConnectionHandler));
workingthread.Start();

}

}
catch (Exception e)
{
eventLog2.WriteEntry("Error in Listener:" + e.Message,
EventLogEntryType.Error);
return;
}

}

....
public void TheConnectionHandler()
{

_telnetSocket = (TcpClient)connectionQueue.Dequeue();
_clientStream = _telnetSocket.GetStream();

while (true)
{

_bytesRead = 0;

try
{

_bytesRead = _clientStream.Read(message, 0,
4096); //message

}
catch
{
//a socket error has occured
break;
}
if (_bytesRead == 0)
{
break;
}

statusMessage += ASCII.GetString(message, 0,
_bytesRead);

[SNIP]

_telnetSocket.Close();
_clientStream.Close();
}

[pbd22]

OK, thanks.
I sort of figured that but am unclear where exactly to post the stop
command.
If I do something like the below, the intllisense tells me that
listener.stop() will
never be reachable. Where, exactly, do i call stop??

Thanks.
TcpListener listener = new TcpListener(_telnetServer,
_telnetPort);
listener.Start();

while (true)
{

_telnetSocket = listener.AcceptTcpClient();
connectionQueue.Enqueue(_telnetSocket);

Thread workingthread = new Thread(new
ThreadStart(TheConnectionHandler));
workingthread.Start();

}
listener.Stop();

[pbd22]

anybody care to address the OP? :)

Should I be flusing my queue and closing the listener?
If so, where exactly should I be placing my closing logic?

I'd appreciate any help here. Thanks!

[Peter Duniho]

On Thu, 31 Jan 2008 06:12:10 -0800, pbd22 <du*****@gmail.comwrote:

OK, thanks.
I sort of figured that but am unclear where exactly to post the stop
command.
If I do something like the below, the intllisense tells me that
listener.stop() will
never be reachable. Where, exactly, do i call stop??

Where you call it now would be fine, if you had any way to exit the loop.
So, one fix is to change the loop so there's a way to exit it. :)

Personally, I wouldn't bother with the loop. I'd use the asynchronous API
so that I didn't have a thread sitting blocked at a call to an Accept
method, and thus I could stop and close the socket wherever I like without
worrying about some thread that I needed to coordinate with.

But barring that, another alternative would be to put a try/catch around
the call to AcceptTcpClient() and then just stop the listening socket from
somewhere else when you need to shut down the service. Then you catch the
exception that's thrown when the socket is stopped and closed, and in that
way detect that it's time to exit the loop (of course, in that scenario
there's no need to call Stop() after the loop, since calling Stop() and
Close() would be what got you out of the loop in the first place :) ).

Pete

[pbd22]

Thanks Pete.

So, something like this?

TcpListener listener = new TcpListener(_telnetServer, _telnetPort);
listener.Start();

while (true)
{
try
{
_telnetSocket = listener.AcceptTcpClient();
}
catch (Exception)
{
break;
}
finally
{
connectionQueue.Enqueue(_telnetSocket);
Thread workingthread = new Thread(new
ThreadStart(TheConnectionHandler));
workingthread.Start();
}

}

And, elsewhere in the program, when it is time to exit, i call:

_telnetSocket.Close()?

Thanks again,
Peter

[Peter Duniho]

On Fri, 01 Feb 2008 09:37:58 -0800, pbd22 <du*****@gmail.comwrote:

Thanks Pete.

So, something like this?

No, definitely not. The "finally" clause will _always_ execute, whether
an exception occurs or not. You don't want to go starting up a new client
connection thread if AccepTcpClient() throws an exception.

So, skip the "finally" clause...just leave that code outside the try/catch
block, and leave the "break" in the "catch" clause so that the loop exits
when an exception is thrown.

Pete

[pbd22]

Pete:

What exactly am I doing wrong here?

Cannot access a disposed object.
Object name: 'System.Net.Sockets.NetworkStream'.

I pretty easy stab is that I have closed my network stream and i am
trying to open it again.
What I don't get is that the prior connection closed everything and
the next user has to log on again (telnet 192.22.23.4).
So, shouldn't the new session open the stream as it always does?

Peter

[pbd22]

Thanks.

I think the "refreshed data" may be my problem. How do I ensure that,
on the next
connection, the buffer is clean and that no "old" data will be
processed?

For what it is worth, If something goes bad in my program (either via
user logic or program error) this is
what i use:

private void SendResponse(string message)
{

//add some message to the buffer here...

_clientStream.Write(buffer, 0, buffer.Length);
loginState = LoginState.Login;
_telnetSocket.Close();

}
Here is my handler that sets up the connection

public void TheConnectionHandler()
{

_telnetSocket = (TcpClient)connectionQueue.Dequeue();
_clientStream = _telnetSocket.GetStream();

buffer = ASCII.GetBytes(" ");
_clientStream.Write(buffer, 0, buffer.Length);
_clientStream.Flush();

while (true)
{

_bytesRead = 0;

try
{

//blocks until a client sends a message
_bytesRead = _clientStream.Read(message, 0,
4096); //message

}
catch
{
//a socket error has occured
break;
}
if (_bytesRead == 0)
{
break;
}

statusMessage += ASCII.GetString(message, 0,
_bytesRead);

// and so on...

PS. "I pretty easy stab = A pretty easy stab". Was typing fast.

[pbd22]

Yeah, its the statusMessage variable.

Its not clean when a new connection happens.

A clean version is:

statusMessage = <x><y></y><z></z></x>

When the error happens, statusMessage reads:

statusMessage = <x><y></y><z></z></x><

the last "<" must have carried over from the former connection.

How do I make sure this doesn't happen?

Thanks.
Peter