Socket.EndConnect doesn't throw expected exception

[Guest]

Greetings,

Hope I'm posting in the right group.

I set up a Socket with my local IP and a port on which nothing is listening.
When I use .Connect, I get the expected SocketException 10061 No connection
could be made because the target machine actively refused it.

Now, when I use .BeginConnect / .EndConnect no exception is thrown on
..EndConnect and the code continues. I get an error on .BeginReceive telling
me the Socket is not connected. If I try the .BeginConnect / .EndConnect a
second time, I do get the expected 10061 ErrorCode.

This behaves the same in .NET 1.1 and 2.0. Am I missing something or is
there a reason why the first .EndConnect does not throw an exception like I
expect it to?

Thanks,
Mike

 

[Vadym Stetsyak]

Strange... I cannot reproduce this situation...

Here is the code, it is based on .NET 2.0

namespace Client
{
class Program
{
public static ManualResetEvent allDone =
new ManualResetEvent(false);

public static void BeginConnect1(string host, int port)
{

IPAddress[] IPs = Dns.GetHostAddresses(host);

Socket s = new Socket(AddressFamily.InterNetwork,
SocketType.Stream,
ProtocolType.Tcp);

allDone.Reset();

Console.WriteLine("Establishing Connection to {0}",
host);
s.BeginConnect(IPs[0], port,
new AsyncCallback(ConnectCallback1), s);

// wait here until the connect finishes.
// The callback sets allDone.
allDone.WaitOne();

Console.WriteLine("Connection established");
}

public static void ConnectCallback1(IAsyncResult ar)
{
allDone.Set();
Socket s = (Socket)ar.AsyncState;
s.EndConnect(ar); //here i have the exception if noone is
listering on the remote address
}

static void Main(string[] args)
{
BeginConnect1("192.168.0.15", 6666);

Console.ReadLine();
}
}
}

 

[Guest]

Hello Vadym,

Thanks for the reply. I was not using a ManualResetEvent. Apparently that is
the problem. When I do use one, I get the exception as expected.

Then I took your code and removed the ManualResetEvent. I expected to get no
exception, but the exception still occurred.

I'm not sure what the difference is, although my code is a Windows Service
and not a console app.

Thanks,
Mike

Strange... I cannot reproduce this situation...

Here is the code, it is based on .NET 2.0

namespace Client
{
class Program
{
public static ManualResetEvent allDone =
new ManualResetEvent(false);

public static void BeginConnect1(string host, int port)
{

IPAddress[] IPs = Dns.GetHostAddresses(host);

Socket s = new Socket(AddressFamily.InterNetwork,
SocketType.Stream,
ProtocolType.Tcp);

allDone.Reset();

Console.WriteLine("Establishing Connection to {0}",
host);
s.BeginConnect(IPs[0], port,
new AsyncCallback(ConnectCallback1), s);

// wait here until the connect finishes.
// The callback sets allDone.
allDone.WaitOne();

Console.WriteLine("Connection established");
}

public static void ConnectCallback1(IAsyncResult ar)
{
allDone.Set();
Socket s = (Socket)ar.AsyncState;
s.EndConnect(ar); //here i have the exception if noone is
listering on the remote address
}

static void Main(string[] args)
{
BeginConnect1("192.168.0.15", 6666);

Console.ReadLine();
}
}
}


--
Vadym Stetsyak aka Vadmyst
http://vadmyst.blogspot.com

Greetings,

Hope I'm posting in the right group.

I set up a Socket with my local IP and a port on which nothing is
listening.
When I use .Connect, I get the expected SocketException 10061 No
connection
could be made because the target machine actively refused it.

Now, when I use .BeginConnect / .EndConnect no exception is thrown on
.EndConnect and the code continues. I get an error on .BeginReceive
telling
me the Socket is not connected. If I try the .BeginConnect / .EndConnect a
second time, I do get the expected 10061 ErrorCode.

This behaves the same in .NET 1.1 and 2.0. Am I missing something or is
there a reason why the first .EndConnect does not throw an exception like
I
expect it to?

Thanks,
Mike

 

[Vadym Stetsyak]

I've removed event from the code, and guess what - I'm still getting
exception...

What is the value of Socket.Connected value, when connection callback is
called?

Maybe as a quick solution would be the check if
Socket.Connected == true....

--
Vadym Stetsyak aka Vadmyst
http://vadmyst.blogspot.com

Hello Vadym,

Thanks for the reply. I was not using a ManualResetEvent. Apparently that
is
the problem. When I do use one, I get the exception as expected.

Then I took your code and removed the ManualResetEvent. I expected to get
no
exception, but the exception still occurred.

I'm not sure what the difference is, although my code is a Windows Service
and not a console app.

Thanks,
Mike

Strange... I cannot reproduce this situation...

Here is the code, it is based on .NET 2.0

namespace Client
{
class Program
{
public static ManualResetEvent allDone =
new ManualResetEvent(false);

public static void BeginConnect1(string host, int port)
{

IPAddress[] IPs = Dns.GetHostAddresses(host);

Socket s = new Socket(AddressFamily.InterNetwork,
SocketType.Stream,
ProtocolType.Tcp);

allDone.Reset();

Console.WriteLine("Establishing Connection to {0}",
host);
s.BeginConnect(IPs[0], port,
new AsyncCallback(ConnectCallback1), s);

// wait here until the connect finishes.
// The callback sets allDone.
allDone.WaitOne();

Console.WriteLine("Connection established");
}

public static void ConnectCallback1(IAsyncResult ar)
{
allDone.Set();
Socket s = (Socket)ar.AsyncState;
s.EndConnect(ar); //here i have the exception if noone
is
listering on the remote address
}

static void Main(string[] args)
{
BeginConnect1("192.168.0.15", 6666);

Console.ReadLine();
}
}
}


--
Vadym Stetsyak aka Vadmyst
http://vadmyst.blogspot.com

Greetings,

Hope I'm posting in the right group.

I set up a Socket with my local IP and a port on which nothing is
listening.
When I use .Connect, I get the expected SocketException 10061 No
connection
could be made because the target machine actively refused it.

Now, when I use .BeginConnect / .EndConnect no exception is thrown on
.EndConnect and the code continues. I get an error on .BeginReceive
telling
me the Socket is not connected. If I try the .BeginConnect /
.EndConnect a
second time, I do get the expected 10061 ErrorCode.

This behaves the same in .NET 1.1 and 2.0. Am I missing something or is
there a reason why the first .EndConnect does not throw an exception
like
I
expect it to?

Thanks,
Mike

 

[Vadym Stetsyak]

Can you post the code, where you're doing async connect?

--
Vadym Stetsyak aka Vadmyst
http://vadmyst.blogspot.com

Hello Vadym,

Thanks for the reply. I was not using a ManualResetEvent. Apparently that
is
the problem. When I do use one, I get the exception as expected.

Then I took your code and removed the ManualResetEvent. I expected to get
no
exception, but the exception still occurred.

I'm not sure what the difference is, although my code is a Windows Service
and not a console app.

Thanks,
Mike

Strange... I cannot reproduce this situation...

Here is the code, it is based on .NET 2.0

namespace Client
{
class Program
{
public static ManualResetEvent allDone =
new ManualResetEvent(false);

public static void BeginConnect1(string host, int port)
{

IPAddress[] IPs = Dns.GetHostAddresses(host);

Socket s = new Socket(AddressFamily.InterNetwork,
SocketType.Stream,
ProtocolType.Tcp);

allDone.Reset();

Console.WriteLine("Establishing Connection to {0}",
host);
s.BeginConnect(IPs[0], port,
new AsyncCallback(ConnectCallback1), s);

// wait here until the connect finishes.
// The callback sets allDone.
allDone.WaitOne();

Console.WriteLine("Connection established");
}

public static void ConnectCallback1(IAsyncResult ar)
{
allDone.Set();
Socket s = (Socket)ar.AsyncState;
s.EndConnect(ar); //here i have the exception if noone
is
listering on the remote address
}

static void Main(string[] args)
{
BeginConnect1("192.168.0.15", 6666);

Console.ReadLine();
}
}
}


--
Vadym Stetsyak aka Vadmyst
http://vadmyst.blogspot.com

Greetings,

Hope I'm posting in the right group.

I set up a Socket with my local IP and a port on which nothing is
listening.
When I use .Connect, I get the expected SocketException 10061 No
connection
could be made because the target machine actively refused it.

Now, when I use .BeginConnect / .EndConnect no exception is thrown on
.EndConnect and the code continues. I get an error on .BeginReceive
telling
me the Socket is not connected. If I try the .BeginConnect /
.EndConnect a
second time, I do get the expected 10061 ErrorCode.

This behaves the same in .NET 1.1 and 2.0. Am I missing something or is
there a reason why the first .EndConnect does not throw an exception
like
I
expect it to?

Thanks,
Mike

 

[Guest]

Hello Vadym,

I hope my last post was clear.

You code (console application): Expected exception occurs, with or without
using ManualResetEvent.

My code (Windows server): Expected exception occurs only when using
ManualResetEvent

Here's the code from my service - with the ManualResetEvent.Set commented
out, the code does not throw an exception as (I think) it should.

private void ConnectToStateSwitchCallback(IAsyncResult ar)
{
try
{
// Retrieve the Socket and end the asynchronous connect
method.
//allDone.Set();
Socket s = (Socket)ar.AsyncState;
s.EndConnect(ar);

You are probably right in checking for Socket.Connected, I will look into
that as MSDN says "whether a Socket is connected to a remote host as of the
last Send or Receive operation." I have not sent or received data as of yet.

What I am doing is to call Socket.BeginReceive a few lines down in the
method snippet above. .BeginReceive will throw a SocketException.ErrorCode of
10057 - socket is not connected. I then try to connect again, and on the
second try, I get the expected exception - ErrorCode 10061.

Thank you for your time. This is not a huge issue for me, as I have two or
three ways to work around it right now. I'm just curious and trying to figure
exactly what is happening.

Can you post the code, where you're doing async connect?

--
Vadym Stetsyak aka Vadmyst
http://vadmyst.blogspot.com

Hello Vadym,

Thanks for the reply. I was not using a ManualResetEvent. Apparently that
is
the problem. When I do use one, I get the exception as expected.

Then I took your code and removed the ManualResetEvent. I expected to get
no
exception, but the exception still occurred.

I'm not sure what the difference is, although my code is a Windows Service
and not a console app.

Thanks,
Mike

Strange... I cannot reproduce this situation...

Here is the code, it is based on .NET 2.0

namespace Client
{
class Program
{
public static ManualResetEvent allDone =
new ManualResetEvent(false);

public static void BeginConnect1(string host, int port)
{

IPAddress[] IPs = Dns.GetHostAddresses(host);

Socket s = new Socket(AddressFamily.InterNetwork,
SocketType.Stream,
ProtocolType.Tcp);

allDone.Reset();

Console.WriteLine("Establishing Connection to {0}",
host);
s.BeginConnect(IPs[0], port,
new AsyncCallback(ConnectCallback1), s);

// wait here until the connect finishes.
// The callback sets allDone.
allDone.WaitOne();

Console.WriteLine("Connection established");
}

public static void ConnectCallback1(IAsyncResult ar)
{
allDone.Set();
Socket s = (Socket)ar.AsyncState;
s.EndConnect(ar); //here i have the exception if noone
is
listering on the remote address
}

static void Main(string[] args)
{
BeginConnect1("192.168.0.15", 6666);

Console.ReadLine();
}
}
}


--
Vadym Stetsyak aka Vadmyst
http://vadmyst.blogspot.com

Greetings,

Hope I'm posting in the right group.

I set up a Socket with my local IP and a port on which nothing is
listening.
When I use .Connect, I get the expected SocketException 10061 No
connection
could be made because the target machine actively refused it.

Now, when I use .BeginConnect / .EndConnect no exception is thrown on
.EndConnect and the code continues. I get an error on .BeginReceive
telling
me the Socket is not connected. If I try the .BeginConnect /
.EndConnect a
second time, I do get the expected 10061 ErrorCode.

This behaves the same in .NET 1.1 and 2.0. Am I missing something or is
there a reason why the first .EndConnect does not throw an exception
like
I
expect it to?

Thanks,
Mike