Receiving data from GPS Device: I have a TCP server setup which is receiving data from various GPS Trackers (GT06). Each GPS devices initiates the request, server accepts it, and starts receiving NMEA data. Problem Is when GPS Connect to Server Error:"An existing connection was forcibly closed by the remote host"
The problem is that I don't know how to receive data from GPS over GPRS/TCP connection. Any suggestions?
using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Net.Sockets;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
namespace T1
{
class Program
{
public class StateObject
{
public const int DEFAULT_SIZE = 1024; //size of receive buffer
public byte[] buffer = new byte[DEFAULT_SIZE]; //receive buffer
public int dataSize = 0; //data size to be received
public bool dataSizeReceived = false; //received data size?
public StringBuilder sb = new StringBuilder(); //received data String
public int dataRecieved = 0;
public Socket workSocket = null; //client socket.
public DateTime TimeStamp; //timestamp of data
public const int BufferSize = 256;
} //end class StateObject
public static AutoResetEvent allDone = new AutoResetEvent(false);
public static AutoResetEvent acceptDone = new AutoResetEvent(false);
static void Main(string[] args)
{
StartListening();
}
public static void StartListening()
{
// Data buffer for incoming data.
byte[] bytes = new Byte[1024];
// Establish the local endpoint for the socket.
// The DNS name of the computer
// running the listener is "host.contoso.com".
IPHostEntry ipHostInfo = Dns.Resolve(Dns.GetHostName());
IPAddress ipAddress = ipHostInfo.AddressList[0];
IPAddress local = IPAddress.Parse("103.118.16.129");
IPEndPoint localEndPoint = new IPEndPoint(ipAddress, 8821);
// Create a TCP/IP socket.
Socket listener = new Socket(AddressFamily.InterNetwork,
SocketType.Stream, ProtocolType.Tcp);
// Bind the socket to the local endpoint and listen for incoming connections.
try
{
listener.Bind(localEndPoint);
listener.Listen(100);
while (true)
{
// Set the event to nonsignaled state.
allDone.Reset();
// Start an asynchronous socket to listen for connections.
Console.WriteLine("Waiting for a connection...");
listener.BeginAccept(new AsyncCallback(AcceptCallback), listener);
// Wait until a connection is made before continuing.
allDone.WaitOne();
}
}
catch (Exception e)
{
Console.WriteLine(e.ToString());
}
// Console.WriteLine("\nPress ENTER to continue...");
// Console.Read();
}
private static void Send(Socket handler, String data)
{
// Convert the string data to byte data using ASCII encoding.
byte[] byteData = Encoding.ASCII.GetBytes(data);
// Begin sending the data to the remote device.
handler.BeginSend(byteData, 0, byteData.Length, 0,
new AsyncCallback(SendCallback), handler);
}
private static void Send(Socket handler, byte[] data)
{
// Convert the string data to byte data using ASCII encoding.
// byte[] byteData = Encoding.ASCII.GetBytes(data);
// Begin sending the data to the remote device.
handler.BeginSend(data, 0, data.Length, 0,
new AsyncCallback(SendCallback), handler);
}
private static void SendCallback(IAsyncResult ar)
{
try
{
// Retrieve the socket from the state object.
Socket handler = (Socket)ar.AsyncState;
// Complete sending the data to the remote device.
int bytesSent = handler.EndSend(ar);
Console.WriteLine("Sent {0} bytes to client.", bytesSent);
handler.Shutdown(SocketShutdown.Both);
handler.Close();
}
catch (Exception e)
{
Console.WriteLine(e.ToString());
}
}
public static void AcceptCallback(IAsyncResult ar)
{
// Signal the main thread to continue.
allDone.Set();
// Get the socket that handles the client request.
Socket listener = (Socket)ar.AsyncState;
Socket handler = listener.EndAccept(ar);
// Create the state object.
StateObject state = new StateObject();
state.workSocket = handler;
handler.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,
new AsyncCallback(ReadCallback), state);
}
static byte[] Unpack(string data)
{
//return null indicates an error
List<byte> bytes = new List<byte>();
// check start and end bytes
if ((data.Substring(0, 4) != "7878") && (data.Substring(data.Length - 4) != "0D0A"))
{
return null;
}
for (int index = 4; index < data.Length - 4; index += 2)
{
bytes.Add(byte.Parse(data.Substring(index, 2), System.Globalization.NumberStyles.HexNumber));
}
//crc test
byte[] packet = bytes.Take(bytes.Count - 2).ToArray();
byte[] crc = bytes.Skip(bytes.Count - 2).ToArray();
uint CalculatedCRC = crc_bytes(packet);
return packet;
}
static public UInt16 crc_bytes(byte[] data)
{
ushort crc = 0xFFFF;
for (int i = 0; i < data.Length; i++)
{
crc ^= (ushort)(Reflect(data[i], 8) << 8);
for (int j = 0; j < 8; j++)
{
if ((crc & 0x8000) > 0)
crc = (ushort)((crc << 1) ^ 0x1021);
else
crc <<= 1;
}
}
crc = Reflect(crc, 16);
crc = (ushort)~crc;
return crc;
}
static public ushort Reflect(ushort data, int size)
{
ushort output = 0;
for (int i = 0; i < size; i++)
{
int lsb = data & 0x01;
output = (ushort)((output << 1) | lsb);
data >>= 1;
}
return output;
}
public static void ReadCallback(IAsyncResult ar)
{
String content = String.Empty;
// Retrieve the state object and the handler socket
// from the asynchronous state object.
StateObject state = (StateObject)ar.AsyncState;
Socket handler = state.workSocket;
// Read data from the client socket.
int bytesRead = handler.EndReceive(ar);
if (bytesRead > 0)
{
if (state.buffer[3] == 1)
{
string input = BitConverter.ToString(state.buffer, 0, bytesRead).Replace("-", "");
Console.WriteLine("Recived {0} bytes to client.", input);
//byte[] bytes = Unpack(input);
//byte[] serialNumber = bytes.Skip(bytes.Length - 2).ToArray();
//byte[] response = { 0x78, 0x78, 0x05, 0x01, 0x00, 0x00, 0x00, 0x0 };
//serialNumber.CopyTo(response, 4);
//UInt16 sendCRC = crc_bytes(response.Take(response.Length - 2).ToArray());
//response[response.Length - 2] = (byte)((sendCRC >> 8) & 0xFF);
//response[response.Length - 1] = (byte)((sendCRC) & 0xFF);
//Send(handler, response);
// handler.Send(response);
}
else
{
// There might be more data, so store the data received so far.
//state.sb.Append(Encoding.ASCII.GetString(state.buffer, 0, bytesRead));
// Check for end-of-file tag. If it is not there, read
// more data.
// content = state.sb.ToString();
Console.WriteLine("Recived {0} bytes to client.", Encoding.ASCII.GetString(state.buffer, 0, bytesRead));
// SaveData(content);
// Not all data received. Get more.
handler.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,
new AsyncCallback(ReadCallback), state);
// }
}
}
}
}
}
