UDPListener: System.Net.Sock ets.SocketExcep tion

[J C]

Hi,

I'm using UDPClient to make a simple DNS server. I notice that
intermittently and unpredictibly I get:

Unhandled Exception: System.Net.Sock ets.SocketExcep tion: An existing
connection
was forcibly closed by the remote host
at System.Net.Sock ets.Socket.Rece iveFrom(Byte[] buffer, Int32 offset,
Int32 s
ize, SocketFlags socketFlags, EndPoint& remoteEP)
at System.Net.Sock ets.UdpClient.R eceive(IPEndPoi nt& remoteEP)
at dnsone_c.CoolUD P.Receive()
at dnsone_c.Progra m.Main(String[] args)

If I try to restart the server right away, I get:

Unhandled Exception: System.Net.Sock ets.SocketExcep tion: Only one usage of
each
socket address (protocol/network address/port) is normally permitted
at System.Net.Sock ets.Socket.DoBi nd(EndPoint endPointSnapsho t,
SocketAddress
socketAddress)
at System.Net.Sock ets.Socket.Bind (EndPoint localEP)
at System.Net.Sock ets.UdpClient.. ctor(IPEndPoint localEP)
at dnsone_c.CoolUD P.Receive()
at dnsone_c.Progra m.Main(String[] args)

After about a minute, this goes away and I can restart the program as usual.

Is the problem maybe that I'm both sending and receiving out of the same
UDPClient object? It's like something's getting in the way and blocking the
port and the program throws a fit.

Thanks,

--Jon
j@fourtentech.c om

[J C]

It appears I can keep the program from erroring out by putting the Receive
and Send calls in a try/catch block, but if anyone has advice on how to
eliminate the problem rather than just mask it, that would be great!

--Jon
"J C" <j@fourtentech. com> wrote in message
news:OG******** ******@TK2MSFTN GP09.phx.gbl...

Hi,

I'm using UDPClient to make a simple DNS server. I notice that
intermittently and unpredictibly I get:

Unhandled Exception: System.Net.Sock ets.SocketExcep tion: An existing
connection
was forcibly closed by the remote host
at System.Net.Sock ets.Socket.Rece iveFrom(Byte[] buffer, Int32 offset,
Int32 s
ize, SocketFlags socketFlags, EndPoint& remoteEP)
at System.Net.Sock ets.UdpClient.R eceive(IPEndPoi nt& remoteEP)
at dnsone_c.CoolUD P.Receive()
at dnsone_c.Progra m.Main(String[] args)

If I try to restart the server right away, I get:

Unhandled Exception: System.Net.Sock ets.SocketExcep tion: Only one usage of
each
socket address (protocol/network address/port) is normally permitted
at System.Net.Sock ets.Socket.DoBi nd(EndPoint endPointSnapsho t,
SocketAddress
socketAddress)
at System.Net.Sock ets.Socket.Bind (EndPoint localEP)
at System.Net.Sock ets.UdpClient.. ctor(IPEndPoint localEP)
at dnsone_c.CoolUD P.Receive()
at dnsone_c.Progra m.Main(String[] args)

After about a minute, this goes away and I can restart the program as
usual.

Is the problem maybe that I'm both sending and receiving out of the same
UDPClient object? It's like something's getting in the way and blocking
the port and the program throws a fit.

Thanks,

--Jon
j@fourtentech.c om

[Vadym Stetsyak]

Hello, J!

Can you post the code sample where you perform network I/O?

J> Unhandled Exception: System.Net.Sock ets.SocketExcep tion: An existing
J> connection
J> was forcibly closed by the remote host
J> at System.Net.Sock ets.Socket.Rece iveFrom(Byte[] buffer, Int32 offset,
J> Int32 s
J> ize, SocketFlags socketFlags, EndPoint& remoteEP)
J> at System.Net.Sock ets.UdpClient.R eceive(IPEndPoi nt& remoteEP)
J> at dnsone_c.CoolUD P.Receive()
J> at dnsone_c.Progra m.Main(String[] args)

Do you use UDPClient.Conne ct(...) method?
--
Regards, Vadym Stetsyak
www: http://vadmyst.blogspot.com

[J C]

Sure... the general idea is:

namespace dnsone_c {
class Program {
static void Main(string[] args) {
CoolUDP myCoolUDP = new CoolUDP();
myCoolUDP.Recei ve();
}
}

class CoolUDP {
private IPEndPoint myEndPoint = new IPEndPoint(IPAd dress.Any, 53);
private IPEndPoint herEndPoint = new IPEndPoint(IPAd dress.Any, 0);

public void Receive() {
UdpClient myListener = new UdpClient(myEnd Point);
byte[] herDNSQuery;
string herDNSQueryText ;

while (true) {
try {
herDNSQuery = myListener.Rece ive(ref herEndPoint);
} catch {
Console.WriteLi ne("Big error (1).");
continue;
}

if( //i like the packet )
//generate a response in byte[] myDNSResponse

try {
myListener.Send (myDNSResponse, myDNSResponse.L ength,
herEndPoint);
}
catch {
Console.WriteLi ne("Big error (2).");
continue;
}
}
}
}
}
}

--Jon

"Vadym Stetsyak" <va*****@ukr.ne t> wrote in message
news:ed******** ******@tk2msftn gp13.phx.gbl...

Hello, J!

Can you post the code sample where you perform network I/O?

J> Unhandled Exception: System.Net.Sock ets.SocketExcep tion: An existing
J> connection
J> was forcibly closed by the remote host
J> at System.Net.Sock ets.Socket.Rece iveFrom(Byte[] buffer, Int32
offset,
J> Int32 s
J> ize, SocketFlags socketFlags, EndPoint& remoteEP)
J> at System.Net.Sock ets.UdpClient.R eceive(IPEndPoi nt& remoteEP)
J> at dnsone_c.CoolUD P.Receive()
J> at dnsone_c.Progra m.Main(String[] args)

Do you use UDPClient.Conne ct(...) method?
--
Regards, Vadym Stetsyak
www: http://vadmyst.blogspot.com