Microsoft selects some sockets



  • From MSDN:

    The following code example uses Select to determine which listening sockets have a connection request.

    IPHostEntry ipHostEntry = Dns.Resolve(Dns.GetHostName());
    IPAddress ipAddress = ipHostEntry.AddressList[0];
    
    Socket socket0 = null;
    Socket socket1 = null; 
    Socket socket2 = null; 
    Socket socket3 = null; 
    Socket socket4 = null; 
    Socket socket5 = null; 
    
    ArrayList listenList = new ArrayList();
    listenList.Add(socket0);
    listenList.Add(socket1);
    listenList.Add(socket2);
    
    ArrayList acceptList = new ArrayList();
    acceptList.Add(socket3);
    acceptList.Add(socket4);
    acceptList.Add(socket5);
    
    for( int i = 0; i < 3; i++ )
    {
      listenList[i] = new Socket(AddressFamily.InterNetwork,
                                 SocketType.Stream,
                                 ProtocolType.Tcp);
      ((Socket)listenList[i]).Bind(new IPEndPoint(ipAddress, 11000 + i));
      ((Socket)listenList[i]).Listen(10);
    }
    
    // Only the sockets that contain a connection request
    // will remain in listenList after Select returns.
    
    Socket.Select(listenList, null, null, 1000);
    
    for( int i = 0; i < listenList.Count; i++ )
    {
      acceptList[i] = ((Socket)listenList[i]).Accept();
    }
    

    live MSDN link
    archive just in case Microsoft MSDNs MSDN again
    oh look they did MSDN MSDN
    here's another archive link (scroll to the right)

    This example code does the following:

    1. Find the current machine's IP address via DNS.
    2. Set 6 variables to null, add 3 of them to each of 2 lists, and then never touch the variables again.
    3. Listen on ports 11000, 11001, and 11002, allowing up to 10 connections on each port to be queued.
    4. Wait UP TO 1 MILLISECOND for any of the listeners to receive a connection.
    5. For each listener that either had a connection waiting or received a connection during that millisecond, accept one connection and replace one of the three nulls in the second list.
    6. As the program has ended, the operating system reclaims the sockets.


  • The C++ snippet seems to have had the beginning cut off at some point, and the main function just exits immediately so who knows what it was ever supposed to do:

          IPHostEntry^ lipa = Dns::Resolve( Dns::GetHostName() );
    
          //Gets three separate local endpoints.
          IPEndPoint^ lep1 = gcnew IPEndPoint( lipa->AddressList[ 0 ],11000 );
          IPEndPoint^ lep2 = gcnew IPEndPoint( lipa->AddressList[ 0 ],11001 );
          IPEndPoint^ lep3 = gcnew IPEndPoint( lipa->AddressList[ 0 ],11002 );
    
          //creates an array of endpoints.
          array<IPEndPoint^>^ipendpoints = gcnew array<IPEndPoint^>(3);
          ipendpoints[ 0 ] = lep1;
          ipendpoints[ 1 ] = lep2;
          ipendpoints[ 2 ] = lep3;
    
          //Creates three separate sockets.
          Socket^ s1 = gcnew Socket( lep1->Address->AddressFamily,SocketType::Stream,ProtocolType::Tcp );
          Socket^ s2 = gcnew Socket( lep2->Address->AddressFamily,SocketType::Stream,ProtocolType::Tcp );
          Socket^ s3 = gcnew Socket( lep3->Address->AddressFamily,SocketType::Stream,ProtocolType::Tcp );
          array<Socket^>^socketList = gcnew array<Socket^>(3);
          socketList[ 0 ] = s1;
          socketList[ 1 ] = s2;
          socketList[ 2 ] = s3;
    
          //Binds and Listens on all sockets in the array of sockets.
          for ( int i = 0; i < 3; i++ )
          {
             socketList[ i ]->Bind( ipendpoints[ i ] );
             socketList[ i ]->Listen( 1000 );
    
          }
    
          //Calls Select to determine which sockets are ready for reading.
          Socket::Select( safe_cast<IList^>(socketList), nullptr, nullptr, 1000 );
    
          //Reads on the sockets returned by Select.
          array<Byte>^buffer = gcnew array<Byte>(1024);
          String^ outString;
          for ( Int32 j = 0; j < (socketList->Length - 1); j++ )
          {
             socketList[ j ]->Receive( buffer );
             outString =  "Socket ";
             outString->Concat( j.ToString(),  " has the message", Encoding::ASCII->GetString( buffer ) );
             Console::WriteLine( outString );
    
          }
       }
    
    };
    
    int main()
    {
       return 0;
    }
    

    Not to mention it is actually C++/CLI instead of C++.


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  • @lb_ said in Microsoft selects some sockets:

    Not to mention it is actually C++/CLI instead of C++.

    Well it is the .NET documentation, so. That seems normal and expected.



  • @blakeyrat Normally the language tabs differentiate, though. I've seen pages with both a C++/CLI tab and a C++ tab.



  • MSDN said:

    AddressFamily.InterNetwork

    InterNetwork

    :butwhy.pgm:



  • @ben_lubar said in Microsoft selects some sockets:

    Microsoft MSDNs MSDN again

    Upvoted just for that.


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