Develop Reference

Socket Exception only when connecting over IP but not localhost

System.Net.Sockets.SocketException (0x80004005): A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond
I only get this error when trying to connect via my public IP, if I use localhost it works fine.
My code:
(Note: Public IP/Local IP and Port have been censored here, but I'm using my public IPV4 Address and a specific port which has been Port forwarded as well as allowed through my computers firewall both inbound and outbound)
(Client):
`
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Net;
using System.Net.Sockets;
namespace RemoteBG
{
public partial class Form1 : Form
{
Socket client;
IPEndPoint remote;
public Form1()
{
InitializeComponent();
IPHostEntry host = Dns.GetHostEntry("PUBLICIP");
IPAddress ipAddress = host.AddressList[0];
IPEndPoint remoteEP = new IPEndPoint(ipAddress, PORT);
Socket sender = new Socket(ipAddress.AddressFamily, SocketType.Stream, ProtocolType.Tcp);
client = sender;
remote = remoteEP;
}
private void TextUpdate(String s)
{
textBox1.AppendText(s + System.Environment.NewLine);
}
private void button1_Click(object sender, EventArgs e)
{
byte[] bytes = new byte[1024];
try
{
// Connect to Remote EndPoint
client.Connect(remote);
Console.WriteLine("Socket connected to {0}",
client.RemoteEndPoint.ToString());
// Encode the data string into a byte array.
byte[] msg = Encoding.ASCII.GetBytes("This is a test<EOF>");
// Send the data through the socket.
int bytesSent = client.Send(msg);
// Receive the response from the remote device.
int bytesRec = client.Receive(bytes);
Console.WriteLine("Echoed test = {0}",
Encoding.ASCII.GetString(bytes, 0, bytesRec));
// Release the socket.
client.Shutdown(SocketShutdown.Both);
client.Close();
}
catch (ArgumentNullException ane)
{
Console.WriteLine("ArgumentNullException : {0}", ane.ToString());
}
catch (SocketException se)
{
TextUpdate("Error connecting to Zang's PC. Error: " + se.ToString());
}
catch (Exception ex)
{
Console.WriteLine("Unexpected exception : {0}", ex.ToString());
}
}
private void button2_Click(object sender, EventArgs e)
{
}
}
}
Server:
using System;
using System.Net;
using System.Net.Sockets;
using System.Text;
namespace RemoteBGServer
{
class Program
{
public static int Main(String[] args)
{
StartServer();
return 0;
}
public static void StartServer()
{
IPHostEntry host = Dns.GetHostEntry("LOCALIP");
IPAddress ipAddress = host.AddressList[0];
IPEndPoint localEndPoint = new IPEndPoint(ipAddress, PORT);
try
{
// Create a Socket that will use Tcp protocol
Socket listener = new Socket(ipAddress.AddressFamily, SocketType.Stream, ProtocolType.Tcp);
// A Socket must be associated with an endpoint using the Bind method
listener.Bind(localEndPoint);
// Specify how many requests a Socket can listen before it gives Server busy response.
// We will listen 10 requests at a time
listener.Listen(10);
Console.WriteLine("Waiting for a connection...");
Socket handler = listener.Accept();
// Incoming data from the client.
string data = null;
byte[] bytes = null;
while (true)
{
bytes = new byte[1024];
int bytesRec = handler.Receive(bytes);
data += Encoding.ASCII.GetString(bytes, 0, bytesRec);
if (data.IndexOf("<EOF>") > -1)
{
break;
}
}
Console.WriteLine("Text received : {0}", data);
byte[] msg = Encoding.ASCII.GetBytes(data);
handler.Send(msg);
handler.Shutdown(SocketShutdown.Both);
handler.Close();
}
catch (Exception e)
{
Console.WriteLine(e.ToString());
}
Console.WriteLine("\n Press any key to continue...");
Console.ReadKey();
}
}
}
`
Expected to see the test message "This is a test" instead got the exception.
This only occurs when using my public ip for IPHostEntry. Localhost works as expected.
Confirmed that the port is forwarded and firewall has exceptions for the port

C# How to do to send more message to Server with Client?

Im writing a Client Server Socket C# with TCP protocoll to create sort of "Client Ask, Server Answer" But when I Execute first command my client close. I should put while somewhere but I don't know where. here is the code:
CLIENT
using System;
using System.Net;
using System.Net.Sockets;
using System.Text;
public class SynchronousSocketClient
{
public static void StartClient()
{
// Data buffer for incoming data.
byte[] bytes = new byte[1024];
// Connect to a remote device.
try
{
// Establish the remote endpoint for the socket.
// This example uses port 11000 on the local computer.
IPHostEntry ipHostInfo = Dns.Resolve(Dns.GetHostName());
IPAddress ipAddress = ipHostInfo.AddressList[0];
IPEndPoint remoteEP = new IPEndPoint(ipAddress, 11000);
// Create a TCP/IP socket.
Socket sender = new Socket(AddressFamily.InterNetwork,
SocketType.Stream, ProtocolType.Tcp);
// Connect the socket to the remote endpoint. Catch any errors.
try
{
sender.Connect(remoteEP);
Console.WriteLine("Socket connected to {0}", sender.RemoteEndPoint.ToString());
Console.WriteLine("Insert text to send to server");
String a = Console.ReadLine(); //This is a test<EOF>
// Encode the data string into a byte array.
byte[] msg = Encoding.ASCII.GetBytes(a);
// Send the data through the socket.
int bytesSent = sender.Send(msg);
// Receive the response from the remote device.
int bytesRec = sender.Receive(bytes);
Console.WriteLine("Echoed test = {0}", Encoding.ASCII.GetString(bytes, 0, bytesRec));
// Release the socket.
//sender.Shutdown(SocketShutdown.Both);
//sender.Close();
}
catch (ArgumentNullException ane)
{
Console.WriteLine("ArgumentNullException : {0}", ane.ToString());
}
catch (SocketException se)
{
Console.WriteLine("SocketException : {0}", se.ToString());
}
catch (Exception e)
{
Console.WriteLine("Unexpected exception : {0}", e.ToString());
}
}
catch (Exception e)
{
Console.WriteLine(e.ToString());
}
}
public static int Main(String[] args)
{
StartClient();
//To avoid Prompt disappear
Console.Read();
return 0;
}
}
SERVER
using System;
using System.Net;
using System.Net.Sockets;
using System.Text;
using System.Collections;
using System.IO;
//using System.Diagnostics;
public class SynchronousSocketListener
{
// Incoming data from the client.
public static string data = null;
public static void StartListening()
{
// Data buffer for incoming data.
byte[] bytes = new Byte[1024];
// Establish the local endpoint for the socket.
// Dns.GetHostName returns the name of the
// host running the application.
IPHostEntry ipHostInfo = Dns.Resolve(Dns.GetHostName());
IPAddress ipAddress = ipHostInfo.AddressList[0];
IPEndPoint localEndPoint = new IPEndPoint(ipAddress, 11000);
// Create a TCP/IP socket.
Socket listener = new Socket(AddressFamily.InterNetwork,
SocketType.Stream, ProtocolType.Tcp);
// Bind the socket to the local endpoint and
// listen for incoming connections.
try
{
listener.Bind(localEndPoint);
listener.Listen(10);
byte[] msg = null;
// Start listening for connections.
while (true)
{
Console.WriteLine("Waiting for a connection...");
// Program is suspended while waiting for an incoming connection.
Socket handler = listener.Accept();
data = null;
// An incoming connection needs to be processed.
while (true)
{
bytes = new byte[1024];
int bytesRec = handler.Receive(bytes);
data += Encoding.ASCII.GetString(bytes, 0, bytesRec);
if (data.Equals("ping"))
{
// Show the data on the console.
Console.WriteLine("Text received : {0}", data);
// Echo the data back to the client.
msg = Encoding.ASCII.GetBytes("pong");
handler.Send(msg);
break;
}
if (data.Equals("dir"))
{
// Show the data on the console.
Console.WriteLine("Text received : {0}", data);
// Echo the data back to the client.
msg = Encoding.ASCII.GetBytes(System.AppDomain.CurrentDomain.BaseDirectory);
handler.Send(msg);
break;
}
if (data.Equals("files"))
{
// Show the data on the console.
Console.WriteLine("Text received : {0}", data);
String files = "";
string[] fileEntries = Directory.GetFiles(System.AppDomain.CurrentDomain.BaseDirectory);
foreach (string fileName in fileEntries)
files += ProcessFile(fileName);
// Echo the data back to the client.
msg = Encoding.ASCII.GetBytes(files);
handler.Send(msg);
break;
}
}
// Show the data on the console.
//Console.WriteLine("Text received : {0}", data);
// Echo the data back to the client.
//byte[] msg = Encoding.ASCII.GetBytes(data);
//handler.Send(msg);
//handler.Shutdown(SocketShutdown.Both);
//handler.Close();
}
}
catch (Exception e)
{
Console.WriteLine(e.ToString());
}
Console.WriteLine("\nPress ENTER to continue...");
Console.Read();
}
public static String ProcessFile(string path)
{
return path += "\n\n" + path;
}
public static void ProcessDirectory(string targetDirectory)
{
// Process the list of files found in the directory.
string[] fileEntries = Directory.GetFiles(targetDirectory);
foreach (string fileName in fileEntries)
ProcessFile(fileName);
// Recurse into subdirectories of this directory.
string[] subdirectoryEntries = Directory.GetDirectories(targetDirectory);
foreach (string subdirectory in subdirectoryEntries)
ProcessDirectory(subdirectory);
}
public static int Main(String[] args)
{
StartListening();
return 0;
}
}
Now If you copy paste this code and execute Server and then Client, you can write something into CLient prompt and get an answers but at 2 attempt CLient close because there is no while that continues the process! I tried put while out of try and into but code crashed! An Help would be appreciate an help or solution is the same, just get an answer :)
Thank you everyone

I have limited knowledge working with sockets. However I know you should only call the following once:
Socket handler = listener.Accept();
I added a while loop under the above line and also removed your break statements at the end of your if conditions.
So the new code becomes:
CLIENT
using System;
using System.Net;
using System.Net.Sockets;
using System.Text;
public class SynchronousSocketClient
{
public static void StartClient()
{
// Data buffer for incoming data.
byte[] bytes = new byte[1024];
// Connect to a remote device.
try
{
// Establish the remote endpoint for the socket.
// This example uses port 11000 on the local computer.
IPHostEntry ipHostInfo = Dns.Resolve(Dns.GetHostName());
IPAddress ipAddress = ipHostInfo.AddressList[0];
IPEndPoint remoteEP = new IPEndPoint(ipAddress, 11000);
// Create a TCP/IP socket.
Socket sender = new Socket(AddressFamily.InterNetwork,
SocketType.Stream, ProtocolType.Tcp);
// Connect the socket to the remote endpoint. Catch any errors.
try
{
sender.Connect(remoteEP);
Console.WriteLine("Socket connected to {0}", sender.RemoteEndPoint.ToString());
while (true)
{
Console.WriteLine("Insert text to send to server");
String a = Console.ReadLine(); //This is a test<EOF>
// Encode the data string into a byte array.
byte[] msg = Encoding.ASCII.GetBytes(a);
// Send the data through the socket.
int bytesSent = sender.Send(msg);
// Receive the response from the remote device.
int bytesRec = sender.Receive(bytes);
Console.WriteLine("Echoed test = {0}", Encoding.ASCII.GetString(bytes, 0, bytesRec));
}
// Release the socket.
//sender.Shutdown(SocketShutdown.Both);
//sender.Close();
}
catch (ArgumentNullException ane)
{
Console.WriteLine("ArgumentNullException : {0}", ane.ToString());
}
catch (SocketException se)
{
Console.WriteLine("SocketException : {0}", se.ToString());
}
catch (Exception e)
{
Console.WriteLine("Unexpected exception : {0}", e.ToString());
}
}
catch (Exception e)
{
Console.WriteLine(e.ToString());
}
}
public static int Main(String[] args)
{
StartClient();
//To avoid Prompt disappear
Console.Read();
return 0;
}
}
SERVER
using System;
using System.Net;
using System.Net.Sockets;
using System.Text;
using System.Collections;
using System.IO;
//using System.Diagnostics;
public class SynchronousSocketListener
{
// Incoming data from the client.
public static string data = null;
public static void StartListening()
{
// Data buffer for incoming data.
byte[] bytes = new Byte[1024];
// Establish the local endpoint for the socket.
// Dns.GetHostName returns the name of the
// host running the application.
IPHostEntry ipHostInfo = Dns.Resolve(Dns.GetHostName());
IPAddress ipAddress = ipHostInfo.AddressList[0];
IPEndPoint localEndPoint = new IPEndPoint(ipAddress, 11000);
// Create a TCP/IP socket.
Socket listener = new Socket(AddressFamily.InterNetwork,
SocketType.Stream, ProtocolType.Tcp);
// Bind the socket to the local endpoint and
// listen for incoming connections.
while (true)
{
try
{
//if (!listener.IsBound)
//{
listener.Bind(localEndPoint);
//}
listener.Listen(10);
byte[] msg = null;
// Start listening for connections.
while (true)
{
Console.WriteLine("Waiting for a connection...");
// Program is suspended while waiting for an incoming connection.
Socket handler = listener.Accept();
while (true)
{
data = null;
// An incoming connection needs to be processed.
bytes = new byte[1024];
int bytesRec = handler.Receive(bytes);
data += Encoding.ASCII.GetString(bytes, 0, bytesRec);
if (data.Equals("ping"))
{
// Show the data on the console.
Console.WriteLine("Text received : {0}", data);
// Echo the data back to the client.
msg = Encoding.ASCII.GetBytes("pong");
handler.Send(msg);
//break;
}
if (data.Equals("dir"))
{
// Show the data on the console.
Console.WriteLine("Text received : {0}", data);
// Echo the data back to the client.
msg = Encoding.ASCII.GetBytes(System.AppDomain.CurrentDomain.BaseDirectory);
handler.Send(msg);
//break;
}
if (data.Equals("files"))
{
// Show the data on the console.
Console.WriteLine("Text received : {0}", data);
String files = "";
string[] fileEntries = Directory.GetFiles(System.AppDomain.CurrentDomain.BaseDirectory);
foreach (string fileName in fileEntries)
files += ProcessFile(fileName);
// Echo the data back to the client.
msg = Encoding.ASCII.GetBytes(files);
handler.Send(msg);
//break;
}
}
// Show the data on the console.
//Console.WriteLine("Text received : {0}", data);
// Echo the data back to the client.
//byte[] msg = Encoding.ASCII.GetBytes(data);
//handler.Send(msg);
//handler.Shutdown(SocketShutdown.Both);
//handler.Close();
}
}
catch (Exception e)
{
Console.WriteLine(e.ToString());
}
}
Console.WriteLine("\nPress ENTER to continue...");
Console.Read();
}
public static String ProcessFile(string path)
{
return path += "\n\n" + path;
}
public static void ProcessDirectory(string targetDirectory)
{
// Process the list of files found in the directory.
string[] fileEntries = Directory.GetFiles(targetDirectory);
foreach (string fileName in fileEntries)
ProcessFile(fileName);
// Recurse into subdirectories of this directory.
string[] subdirectoryEntries = Directory.GetDirectories(targetDirectory);
foreach (string subdirectory in subdirectoryEntries)
ProcessDirectory(subdirectory);
}
public static int Main(String[] args)
{
StartListening();
return 0;
}
}

TCP- I can't send data when listening as a server

I can't send data when I listen over TCP.I need to listen all the time incoming connections and I should send some data whenever needed.My server code starts to listen when program loads,but when I try to send data it gives this error:
"Only one usage of each socket address (protocol/network address/port) is normally permitted (typically under load)."
And here is my code:
public void Send(object sender, System.EventArgs e)
{
String str = "08";
String str2 = "4213";
String CRCvalue = CRC("08" + str2);
String str3 = str2 + CRCvalue;
Connect("localhost", "hello localhost " + Guid.NewGuid());
}
static void Connect(String server, String message)
{
try
{
Int32 port = 2101;
TcpClient client = new TcpClient(server, port);
Byte[] data = System.Text.Encoding.ASCII.GetBytes(message);
NetworkStream stream = client.GetStream();
// Send the message to the connected TcpServer.
stream.Write(data, 0, data.Length);
System.Diagnostics.Debug.WriteLine("Sent");
stream.Close();
client.Close();
}
catch (ArgumentNullException e)
{
System.Diagnostics.Debug.WriteLine("ArgumentNullException: {0}", e);
}
catch (SocketException e)
{
System.Diagnostics.Debug.WriteLine("SocketException: {0}", e);
}}
protected override void OnLoad(EventArgs e)
{
CreateServer();
}
private static void CreateServer()
{
var tcp = new TcpListener(System.Net.IPAddress.Any,25565);
tcp.Start();
var listeningThread = new Thread(() =>
{
while (true)
{
var tcpClient = tcp.AcceptTcpClient();
ThreadPool.QueueUserWorkItem(param =>
{
NetworkStream stream = tcpClient.GetStream();
string incomming;
byte[] bytes = new byte[1024];
int i = stream.Read(bytes, 0, bytes.Length);
incomming = System.Text.Encoding.ASCII.GetString(bytes, 0, i);
System.Diagnostics.Debug.WriteLine(incomming);
tcpClient.Close();
}, null);
}
});
Any help will be apprecitated.

The exception tells you that you are trying to open the same server socket more than once. You should close your TcpListener (and join the listening thread) on form close. You could also use a singleton service, which manages the tcp listener (or assign a static field and only create the listener if the field is not set).

webcam frame in a class to serialize and send

I'm trying to serialize a MessageData class and send it by network.
This class contain picture in bitmap that I need to display on a form.
The transmitted bitmap it's a frame that a webcam need to transmit several times each second by network to a WinForm.
This program it's a test and in future will be splitted in two parts, client part with receiver method and winform, and a server part with webcam and sender method.
Actually the Serializing and sending-receiving of the object-picture is not working, the winform is not showing any image if I force picture to pass from the serializing-network process instad of get it directly.
The webcam frames are managed with the Emgu.CV library, and locally it's working very well, but not by remote with the serialization sending of the frames.
All that follow is inside the namespace Idea:
[Serializable]
public class MessageData {
public MessageData(Bitmap img){
Picture = img;
}
public static Bitmap Picture { get; set; }
}
[Serializable]
public class MessageSendData {
public MessageSendData(Bitmap img){
Picture = img;
}
public static Bitmap Picture { get; set; }
}
public partial class Idea : Form
{
//declaring global variables
private Capture capture; //takes images from camera as image frames
private bool captureInProgress; // checks if capture is executing
private TcpListener ascolto;
Bitmap bitmapricevuto;
public Idea()
{
InitializeComponent();
}
private void Idea_Load(object sender, EventArgs e)
{
}
private void ProcessFrame(object sender, EventArgs arg)
{
Image<Bgr, Byte> ImageFrame = capture.QueryFrame(); //line 1
// CamImageBox.Image = byteArrayToImage(MyImageBytes(ImageFrame.ToBitmap()));
// CamImageBox.Image = ImageFrame.ToBitmap();
Thread r = new Thread(Ricevi);
r.Start();
MessageSendData.Picture = ImageFrame.ToBitmap();
Thread s = new Thread(Spedisci);
s.Start();
lock (MessageData.Picture){
CamImageBox.Image = MessageData.Picture;
}
}
private void btnStart_Click(object sender, EventArgs e)
{
#region if capture is not created, create it now
if (capture == null)
{
try
{
capture = new Capture();
}
catch (NullReferenceException excpt)
{
MessageBox.Show(excpt.Message);
}
}
#endregion
if (capture != null)
{
if (captureInProgress)
{ //if camera is getting frames then stop the capture and set button Text
// "Start" for resuming capture
btnStart.Text = "Start!"; //
Application.Idle -= ProcessFrame;
}
else
{
//if camera is NOT getting frames then start the capture and set button
// Text to "Stop" for pausing capture
btnStart.Text = "Stop";
Application.Idle += ProcessFrame;
}
captureInProgress = !captureInProgress;
}
}
private void ReleaseData()
{
if (capture != null)
capture.Dispose();
}
public static void Ricevi()
{
IPAddress address = IPAddress.Parse("127.0.0.1");
TcpListener listener = new TcpListener(address, 8585);
listener.Start();
Bitmap mia;
try
{
using (TcpClient client = listener.AcceptTcpClient())
{
NetworkStream stream = client.GetStream();
IFormatter formatter = new BinaryFormatter();
while (true)
{
lock (MessageData.Picture){
MessageData.Picture = (Bitmap)formatter.Deserialize(stream);
}
}
}
}
catch(Exception ex) { }
return;
}
public static void Spedisci()
{
IPAddress address = IPAddress.Parse("127.0.0.1");
TcpClient client = new TcpClient();
try
{
client.Connect(address, 8585);
// Retrieve the network stream.
NetworkStream stream = client.GetStream();
IFormatter formatter = new BinaryFormatter();
while(true)
{
lock (MessageSendData.Picture) {
formatter.Serialize(stream, MessageSendData.Picture);
//Thread.Sleep(1000);
}
}
}
catch (Exception ex) { }
}
/*
public byte[] MyImageBytes(Image MyImage)
{
ImageConverter converter = new ImageConverter();
return (byte[])converter.ConvertTo(MyImage, typeof(byte[]));
}
public Image byteArrayToImage(byte[] bytesArr)
{
MemoryStream memstr = new MemoryStream(bytesArr);
Image img = Image.FromStream(memstr);
return img;
}
*/
}
}
'
I've realized two methods: 1-First method convert the bitmap in a byte array. 2-Second method convert the byte array in a bitmap. Testing them directly without send the converted bytes by tcp network I see that all software are working. Now I've created two methods "Invia" and "Ricevi" that are sending and receiving with async methods the bytearrays by spliting them in stream of a length of 1024 each. My issue on compiling it's about the Async Task methods returned types. How to fix this threads Task async issues?
'
private void ProcessFrame(object sender, EventArgs arg)
{
Image<Bgr, Byte> ImageFrame = capture.QueryFrame();
invia(MyImageBytes(ImageFrame.ToBitmap()));
CamImageBox.Image = ricevi();
}
public byte[] MyImageBytes(Image MyImage)
{
ImageConverter converter = new ImageConverter();
return (byte[])converter.ConvertTo(MyImage, typeof(byte[]));
}
'
Send (Invia) and Receive(Ricevi) methods last version here showed below are using the chars converted to bytes array and appended to the bitmap bytes array for send and receive the bitmap. Actually I've issues during compiling:
public static void invia(byte[] bytetosend)
{
// Data buffer for incoming data.
byte[] bytes = new byte[1024];
// Connect to a remote device.
try {
// Establish the remote endpoint for the socket.
// This example uses port 11000 on the local computer.
IPHostEntry ipHostInfo = Dns.Resolve(Dns.GetHostName());
IPAddress ipAddress = ipHostInfo.AddressList[0];
IPEndPoint remoteEP = new IPEndPoint(ipAddress,11000);
// Create a TCP/IP socket.
Socket sender = new Socket(AddressFamily.InterNetwork,
SocketType.Stream, ProtocolType.Tcp );
// Connect the socket to the remote endpoint. Catch any errors.
try {
sender.Connect(remoteEP);
Console.WriteLine("Socket connected to {0}",
sender.RemoteEndPoint.ToString());
// Encode the data string into a byte array.
var mahByteArray = new ArrayList<byte>();
mahByteArray.AddRange(bytetosend);
string eof = "<EOF>";
mahByteArray.Insert(0, Convert.ToByte(eof)); // Adds eof bytes to the beginning.
byte[] msg = mahByteArray.ToArray();
// Send the data through the socket.
int bytesSent = sender.Send(msg);
// Receive the response from the remote device.
int bytesRec = sender.Receive(bytes);
Console.WriteLine("Echoed test = {0}",
Encoding.ASCII.GetString(bytes,0,bytesRec));
// Release the socket.
sender.Shutdown(SocketShutdown.Both);
sender.Close();
} catch (ArgumentNullException ane) {
Console.WriteLine("ArgumentNullException : {0}",ane.ToString());
} catch (SocketException se) {
Console.WriteLine("SocketException : {0}",se.ToString());
} catch (Exception e) {
Console.WriteLine("Unexpected exception : {0}", e.ToString());
}
} catch (Exception e) {
Console.WriteLine( e.ToString());
}
}
public static void ricevi()
{
// Data buffer for incoming data.
byte[] bytes = new Byte[1024];
var scambioArray = new ArrayList();
// Establish the local endpoint for the socket.
// Dns.GetHostName returns the name of the
// host running the application.
IPHostEntry ipHostInfo = Dns.Resolve(Dns.GetHostName());
IPAddress ipAddress = ipHostInfo.AddressList[0];
IPEndPoint localEndPoint = new IPEndPoint(ipAddress, 11000);
// Create a TCP/IP socket.
Socket listener = new Socket(AddressFamily.InterNetwork,
SocketType.Stream, ProtocolType.Tcp);
// Bind the socket to the local endpoint and
// listen for incoming connections.
try
{
listener.Bind(localEndPoint);
listener.Listen(10);
// Start listening for connections.
while (true)
{
Console.WriteLine("Waiting for a connection...");
// Program is suspended while waiting for an incoming connection.
Socket handler = listener.Accept();
string eofr = "<EOF>";
byte[] trova = Convert.ToByte(eofr);
// An incoming connection needs to be processed.
while (true)
{
bytes = new byte[1024];
int bytesRec = handler.Receive(bytes);
if (bytes.IndexOf(trova))
{
var mahByteArray = new ArrayList();
mahByteArray.AddRange(bytes);
mahByteArray.Remove(trova);
bytes = mahByteArray.ToArray();
break;
}
scambioArray.AddRange(bytes);
}
// Echo the data back to the client.
byte[] msg = scambioArray.ToArray();
MessageData.Picture = byteArrayToImage(msg);
handler.Shutdown(SocketShutdown.Both);
handler.Close();
}
}
catch (Exception e)
{
Console.WriteLine(e.ToString());
}
}

Try something like this
using System;
using System.Collections.Generic;
using System.Collections;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Net;
using System.Net.Sockets;
using System.IO;
namespace WindowsFormsApplication1
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
public static void invia(byte[] bytetosend)
{
// Data buffer for incoming data.
byte[] bytes = new byte[1024];
// Connect to a remote device.
try
{
// Establish the remote endpoint for the socket.
// This example uses port 11000 on the local computer.
IPHostEntry ipHostInfo = Dns.Resolve(Dns.GetHostName());
IPAddress ipAddress = ipHostInfo.AddressList[0];
IPEndPoint remoteEP = new IPEndPoint(ipAddress, 11000);
// Create a TCP/IP socket.
Socket sender = new Socket(AddressFamily.InterNetwork,
SocketType.Stream, ProtocolType.Tcp);
// Connect the socket to the remote endpoint. Catch any errors.
try
{
sender.Connect(remoteEP);
Console.WriteLine("Socket connected to {0}",
sender.RemoteEndPoint.ToString());
// Encode the data string into a byte array.
var mahByteArray = new List<byte>();
mahByteArray.AddRange(bytetosend);
string eof = "<EOF>";
mahByteArray.Insert(0, Convert.ToByte(eof)); // Adds eof bytes to the beginning.
byte[] msg = mahByteArray.ToArray();
// Send the data through the socket.
int bytesSent = sender.Send(msg);
// Receive the response from the remote device.
int bytesRec = sender.Receive(bytes);
Console.WriteLine("Echoed test = {0}",
Encoding.ASCII.GetString(bytes, 0, bytesRec));
// Release the socket.
sender.Shutdown(SocketShutdown.Both);
sender.Close();
}
catch (ArgumentNullException ane)
{
Console.WriteLine("ArgumentNullException : {0}", ane.ToString());
}
catch (SocketException se)
{
Console.WriteLine("SocketException : {0}", se.ToString());
}
catch (Exception e)
{
Console.WriteLine("Unexpected exception : {0}", e.ToString());
}
}
catch (Exception e)
{
Console.WriteLine(e.ToString());
}
}
public void ricevi()
{
// Data buffer for incoming data.
List<byte> bytes = (new Byte[1024]).ToList();
List<byte> scambioArray = new List<byte>();
// Establish the local endpoint for the socket.
// Dns.GetHostName returns the name of the
// host running the application.
IPHostEntry ipHostInfo = Dns.Resolve(Dns.GetHostName());
IPAddress ipAddress = ipHostInfo.AddressList[0];
IPEndPoint localEndPoint = new IPEndPoint(ipAddress, 11000);
// Create a TCP/IP socket.
Socket listener = new Socket(AddressFamily.InterNetwork,
SocketType.Stream, ProtocolType.Tcp);
// Bind the socket to the local endpoint and
// listen for incoming connections.
try
{
listener.Bind(localEndPoint);
listener.Listen(10);
// Start listening for connections.
while (true)
{
Console.WriteLine("Waiting for a connection...");
// Program is suspended while waiting for an incoming connection.
Socket handler = listener.Accept();
string eofr = "<EOF>";
List<byte> trova = Encoding.UTF8.GetBytes(eofr).ToList();
// An incoming connection needs to be processed.
while (true)
{
bytes = (new byte[1024]).ToList();
int bytesRec = handler.Receive(bytes.ToArray());
if (bytes.Contains(trova[0]))
{
List<byte> mahByteArray = new List<byte>();
mahByteArray.AddRange(bytes);
mahByteArray.Remove(trova[0]);
bytes = mahByteArray.ToArray().ToList();
break;
}
scambioArray.AddRange(bytes);
}
// Echo the data back to the client.
byte[] msg = scambioArray.ToArray();
MemoryStream stream = new MemoryStream(msg);
MessageData.Image = Image.FromStream(stream);
handler.Shutdown(SocketShutdown.Both);
handler.Close();
}
}
catch (Exception e)
{
Console.WriteLine(e.ToString());
}
}
}
}
​

Why does Socket.Receive throw SocketException (10054) when remote host disconnects?

I used to write socket programs in C and can't understand why the above is happening.
My server blocks at a Receive call, when it returns 0, I break out of the while loop and shutdown the thread.
public class MyServer {
public MyServer() {
}
public void Init() {
ThreadPool.QueueUserWorkItem(StartListening);
while (true) {
Console.Read();
}
}
public void StartListening(Object state) {
// Establish the local endpoint for the socket.
IPAddress ipAddress = IPAddress.Parse("127.0.0.1");
IPEndPoint localEndPoint = new IPEndPoint(ipAddress, 11000);
Socket listener = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
try {
// Bind the socket to the local endpoint and listen for incoming connections.
listener.Bind(localEndPoint);
listener.Listen(100);
while (true) {
Console.WriteLine("Waiting for a connection...");
// get connection
Socket client = listener.Accept();
// push client to another thread
ThreadPool.QueueUserWorkItem(HandleClient, client);
}
} catch (Exception e) {
Console.WriteLine(e.ToString());
}
}
private void HandleClient(Object obj) {
// Get the socket that handles the client request.
Socket client = (Socket)obj;
// Create the state object.
StateObject state = new StateObject();
state.workSocket = client;
try {
while (true) {
int bytesRead = client.Receive(state.buffer);
Console.WriteLine("bytesRead=" + bytesRead);
// remote dc.
if (bytesRead == 0)
break;
String content = Encoding.ASCII.GetString(state.buffer, 0, bytesRead);
Console.WriteLine("Read {0} bytes from socket. \n Data : {1}", content.Length, content);
client.Send(state.buffer, 0, state.buffer.Length, 0);
}
} catch (SocketException e) {
Console.WriteLine("SocketException : {0}", e.ToString());
}
client.Shutdown(SocketShutdown.Both);
client.Close();
}
private void Send(Socket handler, String data) {
byte[] byteData = Encoding.ASCII.GetBytes(data);
// Begin sending the data to the remote device.
//handler.BeginSend(byteData, 0, byteData.Length, 0, new AsyncCallback(SendCallback), handler);
}
}
However, when I click on the close button ("x") of the client, server's Receive call throws a SocketException. According to MSDN's Remarks section, this shouldn't happen because I've satisfied both the connection-oriented part (see above) and client shutdown part(see below) conditions.
Client.cs (pseudo):
public class MyClient {
public void Init() {
byte[] bytes = new byte[1024];
Socket sender = null;
try {
IPAddress ipAddress = IPAddress.Parse("127.0.0.1");
IPEndPoint remoteEP = new IPEndPoint(ipAddress, 11000);
sender = new Socket(AddressFamily.InterNetwork,
SocketType.Stream, ProtocolType.Tcp);
sender.Connect(remoteEP);
Console.WriteLine("Socket connected to {0}",
sender.RemoteEndPoint.ToString());
while (true) {
// Encode the data string into a byte array.
String input = Console.ReadLine();
byte[] msg = Encoding.ASCII.GetBytes(input);
// Send the data through the socket.
int bytesSent = sender.Send(msg);
// Receive the response from the remote device.
int bytesRec = sender.Receive(bytes);
Console.WriteLine("Echoed test = {0}",
Encoding.ASCII.GetString(bytes, 0, bytesRec));
}
} catch (ArgumentNullException ane) {
Console.WriteLine("ArgumentNullException : {0}", ane.ToString());
} catch (SocketException se) {
Console.WriteLine("SocketException : {0}", se.ToString());
} catch (Exception e) {
Console.WriteLine("Unexpected exception : {0}", e.ToString());
} finally {
sender.Shutdown(SocketShutdown.Both);
sender.Close();
}
}
}
My shallow understanding of finally blocks is that it will always execute. But it doesn't seem to be the case here.
SO, what did I do wrong here? Should I just catch the exception, close the client socket on the server side and just move on, ignoring it? But I would prefer if an exception were not thrown at all.