TcpListener.AcceptTcpClient Method

Reference

Definition

Namespace:: System.Net.Sockets

Assembly:: System.Net.Sockets.dll

Assembly:: System.dll

Assembly:: netstandard.dll

Source:: TCPListener.cs

Source:: TCPListener.cs

Source:: TCPListener.cs

Important

Some information relates to prerelease product that may be substantially modified before it’s released. Microsoft makes no warranties, express or implied, with respect to the information provided here.

Accepts a pending connection request.

public:
 System::Net::Sockets::TcpClient ^ AcceptTcpClient();

public System.Net.Sockets.TcpClient AcceptTcpClient ();

member this.AcceptTcpClient : unit -> System.Net.Sockets.TcpClient

Public Function AcceptTcpClient () As TcpClient

Returns

TcpClient

A TcpClient used to send and receive data.

Exceptions

InvalidOperationException

The listener has not been started with a call to Start().

SocketException

Use the ErrorCode property to obtain the specific error code. When you have obtained this code, you can refer to the Windows Sockets version 2 API error code documentation for a detailed description of the error.

Examples

In the following code example, the AcceptTcpClient method is used to return a TcpClient. This TcpClient is used to communicate with the newly connected client.

/**
* This program shows how to use the TcpListener class. 
* It creates a TcpListener that listens on the specified port (13000). 
* To run this program at the command line you enter:
* cs_tcpserver
* Any TcpClient that wants to use this server
* has to explicitly connect to an address obtained by the combination of
* the server on which this TcpServer is running and the port 13000. 
* This TcpServer simply echoes back the message sent by the TcpClient, after
* translating it into uppercase. 
**/

#using <System.dll>

using namespace System;
using namespace System::IO;
using namespace System::Net;
using namespace System::Net::Sockets;
using namespace System::Text;

int main()
{
   try
   {
      
      // Set the TcpListener on port 13000.
      Int32 port = 13000;
      TcpListener^ server = gcnew TcpListener(IPAddress::Any, port);
      
      // Start listening for client requests.
      server->Start();
      
      // Buffer for reading data
      array<Byte>^bytes = gcnew array<Byte>(256);
      String^ data = nullptr;
      
      // Enter the listening loop.
      while ( true )
      {
         Console::Write( "Waiting for a connection... " );
         
         // Perform a blocking call to accept requests.
         // You could also use server.AcceptSocket() here.
         TcpClient^ client = server->AcceptTcpClient();
         Console::WriteLine( "Connected!" );
         data = nullptr;
         
         // Get a stream object for reading and writing
         NetworkStream^ stream = client->GetStream();
         Int32 i;
         
         // Loop to receive all the data sent by the client.
         while ( (i = stream->Read( bytes, 0, bytes->Length )) != 0 )
         {
            
            // Translate data bytes to a ASCII string.
            data = System::Text::Encoding::ASCII->GetString( bytes, 0, i );
            Console::WriteLine( String::Format( "Received: {0}", data ) );
            
            // Process the data sent by the client.
            data = data->ToUpper();
            array<Byte>^msg = System::Text::Encoding::ASCII->GetBytes( data );
            
            // Send back a response.
            stream->Write( msg, 0, msg->Length );
            Console::WriteLine( String::Format( "Sent: {0}", data ) );
         }
         
         // Shutdown and end connection
         client->Close();
      }
   }
   catch ( SocketException^ e ) 
   {
      Console::WriteLine( "SocketException: {0}", e );
   }

   Console::WriteLine( "\nHit enter to continue..." );
   Console::Read();
}

/**
* The following sample is intended to demonstrate how to use a
* TcpListener for synchronous communcation with a TCP client
* It creates a TcpListener that listens on the specified port (13000).
* Any TCP client that wants to use this TcpListener has to explicitly connect
* to an address obtained by the combination of the server
* on which this TcpListener is running and the port 13000.
* This TcpListener simply echoes back the message sent by the client
* after translating it into uppercase.
* Refer to the related client in the TcpClient class.
*/
using System;
using System.Text;
using System.IO;
using System.Net;
using System.Net.Sockets;
using System.Threading;

public class TcpListenerSample
{

    static void Main(string[] args)
    {
        try
        {
            // set the TcpListener on port 13000
            int port = 13000;
            TcpListener server = new TcpListener(IPAddress.Any, port);

            // Start listening for client requests
            server.Start();

            // Buffer for reading data
            byte[] bytes = new byte[1024];
            string data;

            //Enter the listening loop
            while (true)
            {
                Console.Write("Waiting for a connection... ");

                // Perform a blocking call to accept requests.
                // You could also use server.AcceptSocket() here.
                TcpClient client = server.AcceptTcpClient();
                Console.WriteLine("Connected!");

                // Get a stream object for reading and writing
                NetworkStream stream = client.GetStream();

                int i;

                // Loop to receive all the data sent by the client.
                i = stream.Read(bytes, 0, bytes.Length);

                while (i != 0)
                {
                    // Translate data bytes to a ASCII string.
                    data = System.Text.Encoding.ASCII.GetString(bytes, 0, i);
                    Console.WriteLine(String.Format("Received: {0}", data));

                    // Process the data sent by the client.
                    data = data.ToUpper();

                    byte[] msg = System.Text.Encoding.ASCII.GetBytes(data);

                    // Send back a response.
                    stream.Write(msg, 0, msg.Length);
                    Console.WriteLine(String.Format("Sent: {0}", data));

                    i = stream.Read(bytes, 0, bytes.Length);
                }

                // Shutdown and end connection
                client.Close();
            }
        }
        catch (SocketException e)
        {
            Console.WriteLine("SocketException: {0}", e);
        }

        Console.WriteLine("Hit enter to continue...");
        Console.Read();
    }
}

' The following sample is intended to demonstrate how to use a
' TcpListener for synchronous communcation with a TCP client
' It creates a TcpListener that connects to the specified port (13000).
' Any TCP client that wants to use this TcpListener has to explicitly connect 
' to an address obtained by the combination of the server
' on which this TcpListener is running and the port 13000.
' This TcpListener simply echoes back the message sent by the client
' after translating it into uppercase. 
' Refer to the related client in the TcpClient class. 
'/


Imports System.IO
Imports System.Net
Imports System.Net.Sockets
Imports System.Text

 _

Class MyTcpListener
   
   Public Shared Sub Main()
      
      Try
         ' Set the TcpListener on port 13000.
         Dim port As Int32 = 13000
         Dim server As New TcpListener(IPAddress.Any, port)
         
         ' Start listening for client requests.
         server.Start()
         
         ' Buffer for reading data
         Dim bytes(1024) As [Byte]
         Dim data As [String] = Nothing
         
         ' Enter the listening loop.
         While True
            Console.Write("Waiting for a connection... ")
            
            ' Perform a blocking call to accept requests.
            ' You could also use server.AcceptSocket() here.
            Dim client As TcpClient = server.AcceptTcpClient()
            Console.WriteLine("Connected!")
            
            data = Nothing
            
            ' Get a stream object for reading and writing
            Dim stream As NetworkStream = client.GetStream()
            
            Dim i As Int32
            
            ' Loop to receive all the data sent by the client.
            i = stream.Read(bytes, 0, bytes.Length)
            While (i <> 0) 
               ' Translate data bytes to a ASCII string.
               data = System.Text.Encoding.ASCII.GetString(bytes, 0, i)
               Console.WriteLine([String].Format("Received: {0}", data))
               
               ' Process the data sent by the client.
               data = data.ToUpper()
               
               Dim msg As [Byte]() = System.Text.Encoding.ASCII.GetBytes(data)
               
               ' Send back a response.
               stream.Write(msg, 0, msg.Length)
               Console.WriteLine([String].Format("Sent: {0}", data))
              
               i = stream.Read(bytes, 0, bytes.Length)

            End While
            
            ' Shutdown and end connection
            client.Close()
         End While
      Catch e As SocketException
         Console.WriteLine("SocketException: {0}", e)
      End Try
      
      Console.WriteLine(ControlChars.Cr + "Hit enter to continue...")
      Console.Read()
   End Sub
End Class

Remarks

AcceptTcpClient is a blocking method that returns a TcpClient that you can use to send and receive data. Use the Pending method to determine if connection requests are available in the incoming connection queue if you want to avoid blocking.

Use the TcpClient.GetStream method to obtain the underlying NetworkStream of the returned TcpClient. The NetworkStream will provide you with methods for sending and receiving with the remote host. When you are through with the TcpClient, be sure to call its Close method. If you want greater flexibility than a TcpClient offers, consider using AcceptSocket.

Note

This member outputs trace information when you enable network tracing in your application. For more information, see Network Tracing in the .NET Framework.

Applies to

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