I am building an app that communicates to a machine via TCP. The issue I have is that I can connect and all is well but once I disconnect and then try and reconnect all I get is error
The code I have in the form is
private void btn_connect_Click(object sender, EventArgs e)
{
try
{
Log(LogMsgType.Normal, String.Format("Connected on {0}\n", DateTime.Now));
string ip = (txt_ipadd_1.Text + "." + txt_ipadd_2.Text + "." + txt_ipadd_3.Text + "." + txt_ipadd_4.Text);
Log(LogMsgType.Normal, String.Format("Connecting to IP address " + ip + " Port # " + txt_port.Text +"\n"));
string con = Codenet.Connect_TCP(ip, Convert.ToInt32(txt_port.Text)); //connect to this one
Log(LogMsgType.Normal, String.Format(con + "\n"));
toolStripStatusLabel1.Text = "Connected";
btn_connect.Visible = false;
btn_disconnect.Visible = true;
ip = "";
}
catch (Exception d)
{
Log(LogMsgType.Error, String.Format("Error..... " + d.StackTrace +"\n"));
}
}
Which goes over to code from the Codenet dll which does the connection and disconnection
public static string Connect_TCP(string ip, int Port)
{
tcpclnt.Connect(ip, Port);
connection_type = "TCP";
return "Connected OK ";
}
public static void DisConnect_TCP()
{
tcpclnt.GetStream().Close();
tcpclnt.Close();
}
The error I get is:
Error..... at System.Net.Sockets.TcpClient.Connect(String hostname, Int32 port) at
comms_engine.Codenet.Connect_TCP(String ip, Int32 Port) in C:\a\code\g_com_test_1\comms_engine\Codenet.cs:line 37 at
comms_test.CommTester.btn_connect_Click(Object sender, EventArgs e) in C:\a\code\g_com_test_1\dll_test\ethernet.cs:line 98
It will not perform the tcpclnt.Connect(ip, Port) even if the ip is different.
It seems that something is still open but what I do not know as the machine has disconnected. I know that as I have UDP in it sending out how many connections it has and I can see then increase and decrease OK.
I tried "public string Connect_TCP(string ip, int Port)" and making a NEW instance of the dll befor calling the connect from the form but that did not work either.
Any ideas what I am doing wrong.
Thanks for answers so far but still I have an issue. I read the MSDN and made a test app and I can now see what is wrong but am clueless on how to fix it at the moment. I am declaring the Client as Static global so I can get it from the connect and disconnect button. I think thta this always creates new instances and I never close them. First time round the machine tells me it has diconnected bu t the app never reconnects In debug mode it falls over at client.Connect(ipEndPoint); with "InvalidOperationException was unhandled" followed by "Once the socket has been disconnected, you can only reconnect again asynchronously, and only to a different EndPoint. BeginConnect must be called on a thread that won't exit until the operation has been completed."
I guess I need to put this Client inside the btn_connect_click and get a pointer to it from inside the disconnect but how?
The full code is
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Net.Sockets;
using System.Net;
using System.IO;
using System.IO.Ports;
using System.Diagnostics;
using System.Threading;
namespace TCP_Test
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
static Socket client = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
private void btn_connect_Click(object sender, EventArgs e)
{
string ip = (txt_ipadd_1.Text + "." + txt_ipadd_2.Text + "." + txt_ipadd_3.Text + "." + txt_ipadd_4.Text);
IPHostEntry ipHost = Dns.GetHostEntry(Dns.GetHostName());
IPAddress ipAddr = IPAddress.Parse(ip);
IPEndPoint ipEndPoint = new IPEndPoint(ipAddr, Convert.ToInt32(txt_port.Text));
// Connect the socket to the remote end point.
client.Connect(ipEndPoint);
rchTxtBx_output.AppendText("connected to " + ipEndPoint + "\n\r");
}
private void btn_disconnect_Click(object sender, EventArgs e)
{
client.Shutdown(SocketShutdown.Both);
client.Disconnect(true);
if (client.Connected)
rchTxtBx_output.AppendText("We're still connnected \n\r");
else
rchTxtBx_output.AppendText("We're disconnected \n\r");
}
}
}
Once you disconnect a TCP socket, it cannot be reconnected. You have to release the socket and create a new one. This is not just limited to the .NET TCPClient class, this is how all socket APIs work in general (WinSock, BSD, etc).
The exception to this rule is the WinSock2-specific DisconnectEx() function, which has a TF_REUSE_SOCKET flag that allows ConnectEx() (and AcceptEx()) to re-use an existing SOCKET instead of requiring a new socket to be created. But that does not apply in your situation.
In the majority of cases, once you disconnect a socket, you have to create a new socket from scratch.
Thanks for the help I have now solved it. See above for full code but below is teh snippet that makes it work. Just add client = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp); inside the connect button. My testing now shows it connects and disconnects and allows reconnect or connect to anothe machine. Only took me two man days to work that out with your help.
static Socket client = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
private void btn_connect_Click(object sender, EventArgs e)
{
if (client.Connected)
{
client.Shutdown(SocketShutdown.Both);
client.Disconnect(true);
client.Close();
}
else
{
client = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
try
{
string ip = (txt_ipadd_1.Text + "." + txt_ipadd_2.Text + "." + txt_ipadd_3.Text + "." + txt_ipadd_4.Text);
IPHostEntry ipHost = Dns.GetHostEntry(Dns.GetHostName());
When the connection is closed, underlying socket(TCPClient.Client returns socket) needs to be set for reuse . Use the Socket.Disconnect(true) instead of close to reconnect on the socket. Check the link:
http://msdn.microsoft.com/en-us/library/system.net.sockets.socket.disconnect(v=vs.90).aspx
Related
I have a hardware that streams data to a windows server, and I have IP and port of this server. Now I want to connect unity app as a TCP client to this server. I have tried many solutions, but still have hard time to figure out best way to do this. Any help is highly appreciated. One issue that I have with current tutorials is that most of them define a unity server and try to connect another unity app as client and mostly based on localhost. However, I just want to connect a unity app as a TCP client to a server which I have IP and port.
Warm regards,
enter image description here
First of all, at the top of your script:
using System;
using System.Net.Sockets;
Then, create an instance of TcpClient and begin the connection:
socket = new TcpClient
{
// dataBufferSize is in bytes
ReceiveBufferSize = dataBufferSize,
SendBufferSize = dataBufferSize
};
socket.BeginConnect(ip, port, ConnectCallback, socket);
In ConnectCallback():
private void ConnectCallback(IAsyncResult asyncResult)
{
socket.EndConnect(asyncResult);
if (!socket.Connected) return;
// stream is a NetworkStream you should declare somewhere
stream = socket.GetStream();
// receiveBuffer is a byte[] you should declare somewhere
receiveBuffer = new byte[dataBufferSize];
stream.BeginRead(receiveBuffer, 0, dataBufferSize, ReceiveCallback, null);
}
In ReceiveCallback():
private void ReceiveCallback(IAsyncResult asyncResult)
{
try
{
int byteLength = stream.EndRead(asyncResult);
if (byteLength <= 0)
{
// Disconnect client
return;
}
// Transfer data from receiveBuffer to data variable for handling
byte[] data = new byte[byteLength];
Array.Copy(receiveBuffer, data, byteLength);
// Handle data in any way you want to
// BeginRead again so you can keep receiving data
stream.BeginRead(receiveBuffer, 0, dataBufferSize, ReceiveCallback, null);
}
catch (Exception e)
{
Console.WriteLine($"Error receiving TCP data: {e.Message}");
}
}
I got this information from this tutorial.
I tried some examples of ZMQ on C++,C# and Python. I am trying to have Request-Reply pattern to connect Android device to PC running UWP with Xamarin forms.
Below is the Requestor code:
public void HelloWorld()
{
var timer = new Timer(60000);
timer.Start();
timer.Elapsed += (sender, args) =>
{
this.Cancel = true;
timer.Stop();
};
// Create
const string endpoint = "tcp://PC_ip:3245";
using (var request = new RequestSocket())
{
request.Bind(endpoint);
Thread.Sleep(2000);
while (!Cancel)
{
request.SendFrame("Requester says hello");
var reply = request.ReceiveFrameString();
Debug.WriteLine("Gets reply {0}",reply);
}
}
}
Reply socket code:
public void HelloWorld()
{
var timer = new Timer(60000);
const string endpoint = "tcp://PC_ip:3245";
timer.Start();
timer.Elapsed += (sender, args) =>
{
timer.Stop();
Cancel = true;
};
using (var replierSocket = new ResponseSocket())
{
replierSocket.Connect(endpoint);
Thread.Sleep(2000);
while (!Cancel)
{
var replyFromRequester = replierSocket.ReceiveFrameString();
Debug.WriteLine("Got reply {0}", replyFromRequester);
replierSocket.SendFrame("Response socket say hello");
}
}
}
Cancel is boolean
I went through some questions posted on this and added delay and these connection code blocks only trigger after button clicks on app.
While debugging , request.ReceiveFrameString() replierSocket.ReceiveFrameString(); are not even hit.
I am new to network programming , I understand that for REQ/REP pattern the code has to be in particular order which I traced and fixed I believe and turned off firewall on my PC so that firewall wont block my incoming connections from Android device.
PC_ip stands for IPv4 address I got from ipconfig /all for my wifi. I also tried external ip of my machine from sites like whatsmyip.org at ResponseSocket but I still dont get response between devices.
Please let me know what am I doing wrong.
Issue replication repository : GitHub/me/XamZeroMq
In the Answer to this question Here:Server Client Application with .NET and Xamarin
the person who answered said: "On Xamarin.Android you can use all of the regular .Net socket classes"
I tried using the code in example of the Microsoft documentation and i had no errors but application just is just displaying like that on the phone:
If I delete the socket code it would display the page normally.My code behind:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Xamarin.Forms;
using Xamarin.Forms.Xaml;
using System.Net;
using System.Net.Sockets;
namespace App14
{
[XamlCompilation(XamlCompilationOptions.Compile)]
public partial class Page2 : ContentPage
{
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.GetHostEntry(Dns.GetHostName());
IPAddress ipAddress = ipHostInfo.AddressList[0];
IPEndPoint localEndPoint = new IPEndPoint(ipAddress, 11000);
// Create a TCP/IP socket.
Socket listener = new Socket(ipAddress.AddressFamily,
SocketType.Stream, ProtocolType.Tcp);
try
{
listener.Bind(localEndPoint);
listener.Listen(10);
// Start listening for connections.
while (true)
{
var label = new Label() { Text = "searching for a connection" };
// Program is suspended while waiting for an incoming connection.
Socket handler = listener.Accept();
label.Text = "Found a Connection";
data = null;
// An incoming connection needs to be processed.
while (true)
{
int bytesRec = handler.Receive(bytes);
data += Encoding.ASCII.GetString(bytes, 0, bytesRec);
if (data.IndexOf("<EOF>") > -1)
{
break;
}
}
// Show the data on the console.
label.Text = "Text received" + 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());
}
}
public Page2 ()
{
StartListening();
Title = "Sign in page";
InitializeComponent();
}
private void page2_click(object sender,EventArgs e)
{
Navigation.PushAsync(new Page1(), true);
}
}
}
Xaml File code:
Why is this?.and can you please provide an example of client mobile or server mobile socket
You are blocking the UI Thread with your StartListening call, since it has a infinite while loop.
The label you create in the while loop is never added as content on the page. Hence the text you add to it will never be shown. You already have a label defined with the name l on the page. In this case you could just use that to add text:
l.Text = "hello";
As commented, you should start your socket listening code on another thread to not block you UI. This could be as simple as writing Task.Run(() => StartListening());. Make sure you understand what this does and possibly how you cancel this Task again when navigating away from the page or during App lifecycle.
If you try to Connect from your mobile with the correct ip address and port number of the Listener when both devices are in the same LAN it should work. If one of the devices is behind a different LAN router/modem you won't be able to connect because the router will block all incoming connections unless you use a port routing mechanism like UPnP.
I am very confused. I cannot find a specific answer to my question.I'm writing my application in core Java specifically.
So, I am simply trying to connect two separate computers.
Computer 'A' is the server, and Computer 'B' is the client.
When the Client connects to the server. This code is about client and server communication in java. I can run both codes in my PC and can connect client and server. But how will I connect 2 computers as a client and server.
Question: I just want to know that can I connect two PC without internet or wireless connection to run this code as a server and client on two different PC.
Can I use ad Hoc network?
Here are my codes for server and client as follows:
MyServer1
{
try
{
System.out.println("Server Started");
ss=new ServerSocket(10);
s=ss.accept();
System.out.println(s);
System.out.println("CLIENT CONNECTED");
dis= new DataInputStream(s.getInputStream());
dos= new DataOutputStream(s.getOutputStream());
ServerChat();
}
catch(Exception e)
{
System.out.println(e);
}
}
public static void main (String as[])
{
new MyServer1();
}
public void ServerChat() throws IOException
{
String str, s1;
do
{
str=dis.readUTF();
System.out.println("Client Message:"+str);
BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
s1=br.readLine();
dos.writeUTF(s1);
dos.flush();
}
while(!s1.equals("bye"));
}
MyClient1
//code for client
import java.io.*;
import java.net.*;
public class MyClient1
{
Socket s;
DataInputStream din;
DataOutputStream dout;
public MyClient1()
{
try
{
//s=new Socket("10.10.0.3,10");
s=new Socket("MyServere1",10);
System.out.println(s);
din= new DataInputStream(s.getInputStream());
dout= new DataOutputStream(s.getOutputStream());
ClientChat();
}
catch(Exception e)
{
System.out.println(e);
}
}
public void ClientChat() throws IOException
{
BufferedReader br= new BufferedReader(newInputStreamReader(System.in));
String s1;
do
{
s1=br.readLine();
dout.writeUTF(s1);
dout.flush();
System.out.println("Server Message:"+din.readUTF());
}
while(!s1.equals("stop"));
}
As long as both computers are on the same network, whether its a peer to peer, LAN or a much wider network, you should be able to. The key is this, if you ping one machine from the other, do you get a hit if yes then they should connect, if not then they won't
CAVEAT: I have not looked at your code and I don't think this question has much to do with programming, it is probably more suited to networking.
I cannot receive a UDP packet on a Windows Azure Virtual Machine. I have done the following:
On the Virtual Machine, via Windows Firewall, I opened up Port 1234* both Inbound and Outbound for both UDP and TCP protocols. I did not add any IP exclusions. The rule should apply to Domain, Private and Public profiles. I am allowing Block Edge Traversal.
In the Azure Management Portal, I added Endpoints for my Virtual Machine instance. I added both UDP and TCP protocol endpoints. Public and Private port numbers are both 1234.
I have two test programs that I wrote: UDPSender and UDPReceiver. Using two computers on my local network, the test programs successfully sent a packet between them. (Edit: I also used UDPTester Android App to successfully send a 'trans-ISP' message to my PC running the UDPReceiver.)
Moving UDPReceiver to my Virtual Machine, I cannot successfully receive a message.
Did I miss anything in my Azure Endpoint configuration? Please Help!
* Port Number changed to protect the innocent.
Test Program Code Below...
UDPSender:
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
textMessage.Text = "Knock, knock";
textIP.Text = "xxx.xxx.xxx.xxx";
textPort.Text = "1234";
}
private void buttonSend_Click(object sender, EventArgs e)
{
UdpClient udpClient = new UdpClient(textIP.Text, Convert.ToInt32(textPort.Text));
Byte[] sendBytes = Encoding.ASCII.GetBytes(textMessage.Text);
try
{
udpClient.Send(sendBytes, sendBytes.Length);
}
catch (Exception ex)
{
Console.WriteLine(ex.ToString());
}
}
}
UDPReceiver:
private static void Main(string[] args)
{
//Creates a UdpClient for reading incoming data.
UdpClient receivingUdpClient = new UdpClient(1234);
while (true)
{
//Creates an IPEndPoint to record the IP Address and port number of the sender.
// The IPEndPoint will allow you to read datagrams sent from any source.
System.Net.IPEndPoint RemoteIpEndPoint = new System.Net.IPEndPoint(System.Net.IPAddress.Any, 0);
try
{
// Blocks until a message returns on this socket from a remote host.
Byte[] receiveBytes = receivingUdpClient.Receive(ref RemoteIpEndPoint);
string returnData = Encoding.ASCII.GetString(receiveBytes);
string messageOut = String.Format("[{0},{1}]#[{2}]: {3}",
RemoteIpEndPoint.Address.ToString(),
RemoteIpEndPoint.Port.ToString(),
DateTime.Now,
returnData.ToString());
Console.WriteLine(messageOut);
}
catch (Exception ex)
{
Console.WriteLine(ex.ToString());
}
}
}
The code looks correct. I compared it against my implementation. Here are the key sections for reference:
Your csdef should have the correct port protocol. You said you did this through the portal, but confirm the settings saved:
<Endpoints>
<InputEndpoint name="UdpEndpoint" protocol="udp" port="8080" localPort="8080" />
</Endpoints>
(from https://github.com/ytechie/LogHub/blob/master/Microsoft.LogHub.Cloud/ServiceDefinition.csdef)
And listening on the correct port was as easy as:
var endPoint = new IPEndPoint(IPAddress.Any, 0);
var udp = new UdpClient(8080);
(from https://github.com/ytechie/LogHub/blob/master/Microsoft.LogHub/Global.asax.cs)
Feel free to take a look at my implementation and look for differences. I did notice that you're using the synchronous version of "Receive", but that shouldn't matter.
I'm also curious if this is PaaS or IaaS. In either case, you'll need to hit against the load balanced endpoint, and not an internal endpoint which would be inaccessible from the internet.