TCP client stream

Question

I'm comunicationg with a email gateway. That gateway has an specific ip and port.

The requests the gateway are JSON formated and the gateway normally responds first whith an proceeding state and then with a confirmation or error state, represented also in JSON.

The code to make the requests and receive the response is:

using System;
using System.IO;
using System.Net;
using System.Net.Sockets;
using System.Text;
using System.Collections.Generic;
using System.Threading;

using Microsoft.Win32;

public class TcpClientSample
{
    public static void SendMessage(TcpClient client, string msg)
    {
        Console.WriteLine("REQUEST:" + msg);

        NetworkStream stream = client.GetStream();

        byte[] myWriteBuffer = Encoding.ASCII.GetBytes(msg);
        stream.Write(myWriteBuffer, 0, myWriteBuffer.Length);

        byte[] myWriteBuffer2 = Encoding.ASCII.GetBytes("\r\n");
        stream.Write(myWriteBuffer2, 0, myWriteBuffer2.Length);

        string gResponse = "";
        BinaryReader r = new BinaryReader(stream);        

        int receivedMessages = 0;
        while (true)
        {     
            while (true)
            {
                char currentChar = r.ReadChar();
                if (currentChar == '\n')
                    break;
                else
                    gResponse = gResponse + currentChar;
            }           

            if (gResponse != "")
            {
                Console.WriteLine("RESPONSE:" + gResponse);
                receivedMessages = receivedMessages + 1;    
            }

            if (receivedMessages == 2)
            {   
                break;
            }

        }        
    }

    public static void Main()
    {
        List<string> messages = new List<string>();        

        for (int i = 0; i < 1; i++)
        {
            String msg = "{ \"user\" : \"James\", \"email\" : \"james@domain.pt\" }";
            messages.Add(msg);
        }

        TcpClient client = new TcpClient();

        client.Connect("someIp", somePort);

        int sentMessages = 0;
        int receivedMessages = 0;
        foreach (string msg in messages)
        {
            Thread newThread = new Thread(() =>
            {
                sentMessages = sentMessages + 1;
                Console.WriteLine("SENT MESSAGES: " + sentMessages);
                SendMessage(client, msg);
                receivedMessages = receivedMessages + 1;
                Console.WriteLine("RECEIVED MESSAGES: " + receivedMessages);                
            });            
            newThread.Start();

        }        

        Console.ReadLine();
    }
}

If I send few emails (up to 10) the network stream is OK.

But if I send thousands of emails I get messed chars lie

:{iyo"asn ooyes" "ncd" 0,"s_d:"4379" nme" 92729,"er_u" ,"ed_t_i" 2#" p cin_d:"921891010-11:11.725,"s" 4663175D0105E6912ADAAFFF6FDA393367" rpy:"rcein"

Why is this?

Don't worry I'm not a spammer :D

score 0 · Answer 1 · answered May 12 '11 at 00:06

When you write a message to a TCP socket, it'll respond with the sent data. When the buffer is full, I expect it's 0, but you advance your send buffer anyway. You should advance it by the return value :)

Edit: it looks like you're using a stream abstraction which writes the internal buffer. The situation is the same. You are saying "the message has been completely sent" when the internal buffer state is not saying this, i.e. position does not equal limit. You need to keep sending until the remaining amount of buffer is 0 before moving on.

score 0 · Accepted Answer · answered May 21 '11 at 12:34

I solved this issue by having a single method just to read from the stream like this:

private TcpClient client;
private NetworkStream stream;

public void ListenFromGateway()
{
   ...
   while (true)
      {
         byte[] bytes = new byte[client.ReceiveBufferSize];

         //BLOCKS UNTIL AT LEAST ONE BYTE IS READ
         stream.Read(bytes, 0, (int)client.ReceiveBufferSize);

         //RETURNS THE DATA RECEIVED 
         string returndata = Encoding.UTF8.GetString(bytes);

         //REMOVE THE EXCEDING CHARACTERS STARTING ON \r
         string returndata = returndata.Remove(returndata.IndexOf('\r'));

         ...
}

Thanks for the help

TCP client stream

2 Answers2