I am creating a C# application in which I send files over a LAN connection via sockets, but I encounter an "System.NotSupportedException" when I call the Send function
This is the function of the receiver of the file.
Socket _newSocket;
List<byte> endBuffer;
// Used to connect to the server
private void button1_Click(object sender, EventArgs e)
{
_newSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
_newSocket.Connect(IPAddress.Parse("127.0.0.1"), _PORT);
}
// Used to Receive the file
private void button3_Click(object sender, EventArgs e)
{
_newSocket.Receive(endBuffer.ToArray(), SocketFlags.None);
MessageBox
.Show(Encoding.ASCII.GetString(endBuffer.ToArray(), 0, endBuffer.Count));
}
This is the function I used to start the server.
void SetupServer(object sender)
{
Button temp = (Button)sender;
temp.Enabled = false;
_serverSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
_serverSocket.Bind(new IPEndPoint(IPAddress.Parse(txtConnectToIP.Text), _PORT));
_serverSocket.Listen(5);
_serverSocket.BeginAccept(AcceptCallback, null);
}
void AcceptCallback(IAsyncResult AR)
{
Socket socket;
try
{
socket = _serverSocket.EndAccept(AR);
}
catch
{
MessageBox.Show("Not Working!");
return;
}
_clientSockets.Add(socket);
int id = _clientSockets.Count - 1;
IPAddress ip = IPAddress.Parse(_serverSocket.LocalEndPoint.ToString().Split(':')[0]);
string HostName = Dns.GetHostEntry(ip).HostName.Split('.')[0];
string finalName = HostName + " (" + ip.ToString() + ")";
AddClientForSelectionCallback(finalName);
}
This is the send function.
byte[] postBuffer = Encoding.ASCII.GetBytes("Sending Complete!");
void Send(string filePath)
{
try
{
_serverSocket.SendFile(filePath, null, postBuffer, TransmitFileOptions.ReuseSocket);
}
catch (Exception ec)
{
MessageBox.Show("Failed with error message:\n "+ ec);
}
}
Lastly, how would Receive the file sent because _newSocket.Receive() does not seem to work. I have looked at storing its result in a var, but Receive returns nothing and I will try using ConnectAsync.
Help would really be appreciated.
In your program, _serverSocket is the socket that accepts incoming connections, you cannot send data to it.
As soon as a connection is accepted, you get the socket for that connection:
socket = _serverSocket.EndAccept(AR);
You can use this socket instance to communicate with that specific client.
Related
I have a small server that is received and sends the message back to the client.
this is the client-side
when I open the client it will connect to server through Connect()
public Form1()
{
InitializeComponent();
Connect();
CheckForIllegalCrossThreadCalls = false;
}
this is my connect
void Connect()
{
ipep = new IPEndPoint(IPAddress.Parse("127.0.0.1"), 9999);
server = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
try
{
server.Connect(ipep);
}
catch (SocketException e)
{
MessageBox.Show(Convert.ToString(e));
}
Thread listen = new Thread(Receive);
listen.IsBackground = true; ;
listen.Start();
}
and I have a receive like this
void Receive()
{
datarec = new byte[1024];
try
{
while (true)
{
string StringData;
rec = server.Receive(datarec);
StringData = Encoding.ASCII.GetString(data, 0, rec);
txtShow.Text = StringData;
}
}
catch
{
Close();
}
}
and I send data through a button have Send method
void Send(string s)
{
data = new byte[1024];
data = Encoding.ASCII.GetBytes(s);
server.Send(data, data.Length, SocketFlags.None);
}
Send button
private void button1_Click(object sender, EventArgs e)
{
string s = txtText.Text;
Send(s);
}
this is the server-side
I have a thread server
public static void Process(Socket client)
{
byte[] data = new byte[1024];
int recv;
string dataInput;
IPEndPoint clientep = (IPEndPoint)client.RemoteEndPoint;
Console.WriteLine("Connected with {0} at port {1}", clientep.Address, clientep.Port);
while (true)
{
try
{
recv = client.Receive(data);
dataInput = Encoding.ASCII.GetString(data, 0, recv);
Console.WriteLine(dataInput);
client.Send(data);
}
catch (SocketException e)
{
Console.WriteLine(e);
}
}
}
this is the server main
public static void Main()
{
byte[] rec = new byte[1024];
IPEndPoint ipep = new IPEndPoint(IPAddress.Any, 9999);
Socket server = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
server.Bind(ipep);
server.Listen(10);
Console.WriteLine("Waiting for client...");
Console.WriteLine("LOG CHAT");
while (true)
{
Socket client = server.Accept();
Core core = new Core();
Thread t = new Thread(() => Core.Process(client));
t.Start();
}
}
the server receive message but when it sends a message back it has an error "An established connection was aborted by the software in your host machine"
Can you guys tell me where I was wrong and how can I fix it?
When you call client.Send(data) in your server code, you will send the whole 1024 byte buffer back to the client, not just the data received.
Encoding.ASCII.GetString in the client could fail when processing this garbage and the exception will close the connection.
Try to replace client.Send(data) by client.Send(data, recv, SocketFlags.None).
Also, you should not update UI controls directly from a background thread, Use Control.Invoke for this. Failing to do so will also throw an exception and close the connection.
The form from this code does not appear. How can I get it to show? Through the console, everything works.
void Form1_Load(object sender, EventArgs e)
{
String host = Dns.GetHostName();//name kompa
//ip pc
IPAddress ip = Dns.GetHostByName(host).AddressList[0];
const int port = 2222;
label1.Text = host;
label2.Text = "Сервер запущен на " + ip.ToString() + ":" + port.ToString();
server.serversocket = new Socket(ip.AddressFamily, SocketType.Stream, ProtocolType.Tcp);
server.serversocket.Bind(new IPEndPoint(ip, port));
server.serversocket.Listen(100);
//ошибочка в цикле
while (server.work)
{
MessageBox.Show("dsff");
Socket handle = server.serversocket.Accept();
richTextBox1.AppendText("новое подключение" + handle.RemoteEndPoint.ToString());
new user(handle);
}
As Hans Passant said, you are blocking the GUI thread with a while loop. That will just not do. Events must return asap and can never run indefinitely. And this Form_Load can not return until the server stops working.
It is very common mistake and basically the reason we all went crazy for multitasking and multithreading this century. You can't even do a word processor without it anymore.
You are blocking the ui thread. Using a separate thread for the synchronous socket server would be a solution. The other option would be to use an asynchronous socket so that the execution of the application is not blocked while it waits for a connection. Based on the socket code samples.
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
InitSocketServer();
}
internal void InitSocketServer()
{
IPHostEntry ipHostInfo = Dns.Resolve(Dns.GetHostName());
var ipAddress = ipHostInfo.AddressList[0];
IPEndPoint localEndPoint = new IPEndPoint(ipAddress, 11000);
try
{
Socket listener = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
listener.Bind(localEndPoint);
listener.Listen(100);
listener.BeginAccept(AcceptCallback, listener);
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
}
private void AcceptCallback(IAsyncResult ar)
{
Socket listener = (Socket)ar.AsyncState;
Socket handler = listener.EndAccept(ar);
string data = null;
while (true)
{
var bytes = new byte[1024];
int bytesRec = handler.Receive(bytes);
data += Encoding.ASCII.GetString(bytes, 0, bytesRec);
if (data.IndexOf("<EOF>") > -1)
{
break;
}
}
MessageBox.Show(handler.RemoteEndPoint + " : " + data);
byte[] msg = Encoding.ASCII.GetBytes(data);
handler.Send(msg);
handler.Shutdown(SocketShutdown.Both);
handler.Close();
}
private void button1_Click(object sender, EventArgs e)
{
MessageBox.Show("Test button click");
}
}
I'm pretty new to this, I just want to send a message from my console server window to the client.
Here's my server:
static void Main(string[] args)
{
try
{
IPEndPoint localEndPoint = new IPEndPoint(IPAddress.Any, 8000);
Socket newsock = new Socket(AddressFamily.InterNetwork,
SocketType.Stream, ProtocolType.Tcp);
newsock.Bind(localEndPoint);
newsock.Listen(10);
Socket client = newsock.Accept();
if (client.Connected)
{
Console.WriteLine("client connected.");
}
string msg = "Who's there?";
byte[] buffer = new byte[msg.Count()];
buffer = Encoding.ASCII.GetBytes(msg);
client.Send(buffer);
It works fine when i use client.Send() above, but when when I do as follows below I receive nothing on the other end. Since the client is connected, I see no reason why it fails.
while (client.Connected)
{
Console.WriteLine("enter msg: ");
string userMsg = Console.ReadLine();
byte[] userBuffer = new byte[userMsg.Count()];
userBuffer = Encoding.ASCII.GetBytes(userMsg);
client.Send(userBuffer);
Console.ReadKey();
}
}
catch (Exception e)
{
Console.WriteLine("Error: " + e);
}
}
Here's the code for the client:
public partial class MainWindow : Window
{
Socket server = new Socket(AddressFamily.InterNetwork,
SocketType.Stream, ProtocolType.Tcp);
IPEndPoint ipep = new IPEndPoint(IPAddress.Parse("127.0.0.1"), 8000);
byte[] buffer = new byte[12];
public MainWindow()
{
InitializeComponent();
}
private void btn_Connect_Click(object sender, RoutedEventArgs e)
{
server = new Socket(AddressFamily.InterNetwork,
SocketType.Stream, ProtocolType.Tcp);
server.Connect(ipep);
if (server.Connected)
{
txt_Log.AppendText("\nConnected to target server.");
}
btn.IsEnabled = false;
btn_disc.IsEnabled = true;
}
private void btn_Disconnect_Click(object sender, RoutedEventArgs e)
{
server.Close();
if (!server.Connected)
{
txt_Log.AppendText("\nDisconnected to target server.");
}
btn.IsEnabled = true;
btn_disc.IsEnabled = false;
}
private void btn_Fetch_Click(object sender, RoutedEventArgs e)
{
if (buffer != null)
{
using (server)
{
server.Receive(buffer);
txt_Log.AppendText(System.Text.Encoding.Default.GetString(buffer));
buffer = null;
}
}
else
{
txt_Log.AppendText("\nNo data to send.");
}
}
}
Well I've run your server code. No problems there...
For the client, it seemed you dispose the server, which drops the connnection? and null the buffer, so you can't re-use that either....
I wrote some test client code which seemed to work fine
class Program
{
static void Main(string[] args)
{
Socket server = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
server.Connect("127.0.0.1", 8000);
byte[] buffer = new byte[1024];
while (true)
{
int bytes = server.Receive(buffer);
Console.WriteLine(System.Text.Encoding.Default.GetString(buffer, 0, bytes));
}
}
}
Note that the point of this you don't disconnect the client every time you read a packet, and if you null your static before and then null check it is going to be null so fetch will only work once, therefore don't do it!
Also as Mark said, check the number of bytes read from the call the Receive so you can tell how many bytes to decode.
Change
private void btn_Fetch_Click(object sender, RoutedEventArgs e)
{
if (buffer != null)
{
using (server)
{
server.Receive(buffer);
txt_Log.AppendText(System.Text.Encoding.Default.GetString(buffer));
buffer = null;
}
}
else
{
txt_Log.AppendText("\nNo data to send.");
}
}
To..
private void btn_Fetch_Click(object sender, RoutedEventArgs e)
{
if (buffer != null)
{
server.Receive(buffer);
txt_Log.AppendText(System.Text.Encoding.Default.GetString(buffer));
buffer = null;
}
else
{
txt_Log.AppendText("\nNo data to send.");
}
}
and call dispose when the window is closed
protected override void OnClosed(EventArgs e) {
base.OnClosed(e);
server.Dispose();
}
I have implemented TCP hole punching in C#. What I am getting is, the clients are sending the SYN messages to each other but they are dropped at the opposite routers. The scenario is something like this:
Client:A--------Router:A--------Server--------Router:B--------Client:B
If client:A sends the SYN packet to Client:B, it is dropped at Router:B, which is obvious NAT behavior. But, according to the hole punch scenarios, now if the client:B sends SYN to client:A, it should pass through the NAT at router:A. Here in my case, router:A ,too, drops this packet. In netstat, it shows the conenction with B as SYN_SENT and after couple of seconds, I get a message like "The client has not been responding. Connection failure"
As per my research in this, reason behind dropping, may be silent dropping or active rejection. If it is silent dropping, then the hole should be punched and SYN from B should be passed through NAT at A. And if it is active rejection, the router:A will get the notification message from router:B about dropping and A will close the hole.
The problem is I am not getting any notification message at A. (checked through router log).
I also tried to an already implemented TCP hole pucnhing example taken from
https://github.com/jasonpang/tcp-holepunching
But I am getting the similar results. Help me to find out the solution for this.
I am also doubtful about the timeout for the holes punched at routers.
namespace HolePunching
{
public class HolePunchingClient
{
private Socket _clientSocket;
private Socket _serverSocket;
private Socket _connectSocket;
//private Socket _serverSocket;
private Socket _holePunchedSocket;
public HolePunchingClient (IPEndPoint localEndPoint)
{
/*For the moment, only TCP Hole Punching is supported*/
_clientSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
_clientSocket.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, true);
_clientSocket.Bind(localEndPoint);
//_serverSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
//_serverSocket.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, true);
//_serverSocket.Bind(localEndPoint);
}
private void ProcessClientRequest (object sender, DoWorkEventArgs eventArgs)
{
try
{
IPEndPoint iep = (IPEndPoint)eventArgs.Argument;
_connectSocket.Connect(iep);
Console.WriteLine("Connected correctly with: " + iep);
_serverSocket.Close();
_holePunchedSocket = _connectSocket;
Console.WriteLine("\n\n\nException check clientRequest\n\n\n");
}
catch (Exception e)
{
Console.WriteLine("In ProcessClientRequest: " + e.Message);
return;
}
}
private void ProcessServerRequest (object sender, DoWorkEventArgs eventArgs)
{
try
{
_serverSocket.Listen(10);
Socket s = _serverSocket.Accept();
Console.WriteLine("Received connection from: " + s.RemoteEndPoint);
_holePunchedSocket = s;
Console.WriteLine("\n\n\nException check serverRequest\n\n\n");
}
catch (Exception e)
{
Console.WriteLine("In ProcessServerRequest: " + e.Message);
return;
}
}
private void ProcessRequest (object sender, DoWorkEventArgs eventArgs)
{
while (true)
{
byte[] bytes = new byte[2048];
_clientSocket.Receive(bytes);
MessageType messageType = (MessageType) bytes[0];
Console.WriteLine("MessageType received: " + messageType);
switch (messageType)
{
case MessageType.ConnectClient:
byte[] byteAddress = new byte[4];
byte[] bytePort = new byte[2];
Buffer.BlockCopy(bytes, 1, byteAddress, 0, 4);
Buffer.BlockCopy(bytes, 5, bytePort, 0, 2);
IPEndPoint remoteEndPoint = new IPEndPoint(new IPAddress(byteAddress), BitConverter.ToUInt16(bytePort, 0));
Console.WriteLine("HP will be done towards this address: " + remoteEndPoint);
_connectSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
_connectSocket.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, true);
_connectSocket.Bind(_clientSocket.LocalEndPoint);
_serverSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
_serverSocket.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, true);
_serverSocket.Bind(_clientSocket.LocalEndPoint);
BackgroundWorker bwClient = new BackgroundWorker();
bwClient.DoWork += ProcessClientRequest;
BackgroundWorker bwServer = new BackgroundWorker();
bwServer.DoWork += ProcessServerRequest;
bwClient.RunWorkerAsync(remoteEndPoint);
bwServer.RunWorkerAsync();
break;
}
}
}
public void Connect (IPEndPoint serverEndPoint)
{
_clientSocket.Connect(serverEndPoint);
_clientSocket.Send(BitConverter.GetBytes((byte)MessageType.Register));
BackgroundWorker bw = new BackgroundWorker();
bw.DoWork += ProcessRequest;
bw.RunWorkerAsync();
}
public Socket HolePunch (IPAddress otherAddress)
{
byte[] bytes = new byte[5];
Buffer.BlockCopy(BitConverter.GetBytes((byte)MessageType.RequestClient), 0, bytes, 0, 1);
Buffer.BlockCopy(otherAddress.GetAddressBytes(), 0, bytes, 1, 4);
_clientSocket.Send(bytes);
while (_holePunchedSocket == null)
{
System.Threading.Thread.Sleep(1500);
}
return _holePunchedSocket;
}
}
}
This is the client code, which I have taken from the link above. I'm getting the exception message "No response from another client. Connection failure" while connecting to the client B/A.
client A and B both run the same copies of this program. Either of them will send a request to server to connect with the other client. Server will send the IP-Port combination to both. and the client code will proceed by sending the connect request to each other.(which eventually gets timed out)
I've searched for the better part of the day trying to figure this out, and I'm certain I'm missing a simple solution somewhere.
I'm using an asynchronous socket client connection to monitor incoming data from a TCP connection. I've implemented a ManualResetEvent and Callback method as recommended by the msdn sample, but the Callback method is not able to invoke the methods used to output the received data to my Windows form. How do I take the data received from the socket, and send it to the text box in my form?
I'm certain there's a simple trick that I'm missing somewhere. The sample code is written for a console application. How do I have the form react to incoming data from the Socket?
Update:
I think you've got me on the right track. I tried putting in code to use delegates, but I clearly don't quite understand how delegates work, as it keeps throwing the following errors:
An object reference is required for the non-static field, method, or property 'APRS_SMS_Gateway.MainForm.SockOutputDelegate'
Can you get me a little closer? It's the ConnectCallBack Handler that I'm trying to work on right now, but I want to use the same method (SockOutput) from all the CallBacks.
public partial class MainForm : Form
{
private AutoResetEvent receiveNow;
public delegate void SockOutputDelegatetype(string text); // Define delegate type
public SockOutputDelegatetype SockOutputDelegate;
// The port number for the remote device.
private const int port = 14580;
// ManualResetEvent instances signal completion.
private static ManualResetEvent connectDone =
new ManualResetEvent(false);
private static ManualResetEvent sendDone =
new ManualResetEvent(false);
private static ManualResetEvent receiveDone =
new ManualResetEvent(false);
// The response from the remote device.
private static String response = String.Empty;
public MainForm()
{
InitializeComponent();
SockOutputDelegate = new SockOutputDelegatetype(SockOutput);
}
private void Form1_Load(object sender, EventArgs e)
{
CommSetting.APRSServer = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
//StartClient();
}
private void StartClient()
{
try
{
IPHostEntry ipHostInfo = Dns.GetHostEntry("rotate.aprs.net");
IPAddress ipAddress = ipHostInfo.AddressList[0];
IPEndPoint remoteEP = new IPEndPoint(ipAddress, port);
// Create a TCP/IP socket.
//Socket APRSServer = new Socket(AddressFamily.InterNetwork,
// SocketType.Stream, ProtocolType.Tcp);
// Connect to the remote endpoint.
CommSetting.APRSServer.BeginConnect(remoteEP,
new AsyncCallback(ConnectCallback), CommSetting.APRSServer);
connectDone.WaitOne();
//Show the connect string from the host
Receive(CommSetting.APRSServer);
//receiveDone.WaitOne();
//Show the connection response
//SockOutput(response);
}
catch (Exception e)
{
SockOutput(e.ToString());
}
}
private static void ConnectCallback(IAsyncResult ar)
{
try
{
// Retrieve the socket from the state object.
Socket APRSServer = (Socket)ar.AsyncState;
// Complete the connection.
APRSServer.EndConnect(ar);
// Signal that the connection has been made.
connectDone.Set();
}
catch (Exception e)
{
MainForm.Invoke(MainForm.SockOutputDelegate, e.ToString());
}
}
private static void Receive(Socket client)
{
try
{
// Create the state object.
StateObject state = new StateObject();
state.workSocket = client;
// Begin receiving the data from the remote device.
client.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,
new AsyncCallback(ReceiveCallback), state);
}
catch (Exception e)
{
//throw new ApplicationException(e.ToString());
response = e.ToString();
}
}
private static void ReceiveCallback(IAsyncResult ar)
{
try
{
// Retrieve the state object and the client socket
// from the asynchronous state object.
StateObject state = (StateObject)ar.AsyncState;
Socket client = state.workSocket;
// Read data from the remote device.
int bytesRead = client.EndReceive(ar);
if (bytesRead > 0)
{
// There might be more data, so store the data received so far.
state.sb.Append(Encoding.ASCII.GetString(state.buffer, 0, bytesRead));
// Get the rest of the data.
client.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,
new AsyncCallback(ReceiveCallback), state);
}
else
{
// All the data has arrived; put it in response.
if (state.sb.Length > 1)
{
response = state.sb.ToString();
}
// Signal that all bytes have been received.
receiveDone.Set();
}
}
catch (Exception e)
{
response = e.ToString();
}
}
void SockOutput(string text)
{
txtSockLog.AppendText(text);
txtSockLog.AppendText("\r\n");
}
}
}
It sounds like your socket side is working OK, its just updating the winform that's causing problems. You may find your answer here Update WinForm Controls from another thread _and_ class.