Develop Reference

Named Pipes unexpected result

Have a simple named pipes server:
static void Main(string[] args)
{
StartServer();
Console.Read();
}
static void StartServer()
{
Task.Factory.StartNew(() =>
{
var server = new NamedPipeServerStream("TestPipes");
server.WaitForConnection();
StreamReader reader = new StreamReader(server);
StreamWriter writer = new StreamWriter(server);
while (true)
{
var line = reader.ReadLine();
if (line == "Y")
{
for (int i = 0; i < 5; i++)
writer.WriteLine(i.ToString());
writer.Flush();
}
if (line=="N")
{
for (int i = 10; i < 15; i++)
writer.WriteLine(i.ToString());
writer.Flush();
}
}
});
}
and very simple client:
static void Main(string[] args)
{
//Client
var client = new NamedPipeClientStream(Environment.MachineName, "TestPipes");
client.Connect();
Console.WriteLine($"Connection esteblished at {DateTime.Now}, you may continue");
StreamReader reader = new StreamReader(client);
StreamWriter writer = new StreamWriter(client);
while (true)
{
string input = Console.ReadLine();
if (String.IsNullOrEmpty(input)) continue;
writer.WriteLine(input);
writer.Flush();
string serverString;
while (reader.Peek() >= 0)
{
serverString = reader.ReadLine();
Console.WriteLine(serverString);
}
}
}
but for some reason only first command is being completed.
for example if I enter 'Y' getting output 'Y' and then when 'N' is entered nothing comes from the server.
Need to make it work continuously.
Thank you.

That's because in your client you're defining StreamReader reader = new StreamReader(client); outside of the while loop, so on the first iteration when the reader hits the last line, the underlying stream never gets reset, so reader.Peek() >= 0 yields false for subsequent calls.
Move the declaration of the client reader object inside the while loop:
var client = new NamedPipeClientStream(Environment.MachineName, "TestPipes");
client.Connect();
Console.WriteLine($"Connection esteblished at {DateTime.Now}, you may continue");
StreamWriter writer = new StreamWriter(client);
while (true)
{
StreamReader reader = new StreamReader(client);
string input = Console.ReadLine();
if (String.IsNullOrEmpty(input)) continue;
writer.WriteLine(input);
writer.Flush();
string serverString;
while (reader.Peek() >= 0)
{
serverString = reader.ReadLine();
Console.WriteLine(serverString);
}
}

Using Peek is very rarely good idea, and it's not a good idea here either. For example, try to simulate server delay like this:
var line = reader.ReadLine();
if (line == "Y") {
for (int i = 0; i < 5; i++) {
writer.WriteLine(i.ToString());
writer.Flush();
// delay
Thread.Sleep(100);
}
}
And you will see that your code with Peek (including accepted answer) will fail and just read one line (and on subsequent inputs, like "N", will again display nothing, just like it does now). So your code with Peek is not reliable and will surprisingly fail at the most inappropriate moment.
Instead, let server explicitly mark end of data it sends. For example, with empty line:
if (line == "Y") {
for (int i = 0; i < 5; i++) {
writer.WriteLine(i.ToString());
writer.Flush();
// simulate delay
Thread.Sleep(100);
}
// empty line
writer.WriteLine();
writer.Flush();
}
And on client:
string serverString;
while (true)
{
serverString = reader.ReadLine();
if (!String.IsNullOrWhiteSpace(serverString))
Console.WriteLine(serverString);
else break;
};
This code will work reliably
Moving StreamReader to inner while loop as other answer suggests is also not needed, it looks like it "fixes" your code, but really it doesn't fix anything and just puts your problem under the carpet.

How to create TCP message framing for the stream

Here is how my Client connects to the server:
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;
using System.Net.Sockets;
using System.IO;
using System;
using System.Text.RegularExpressions;
using UnityEngine.SceneManagement;
using Newtonsoft.Json;
using System.Linq;
public class ClientWorldServer : MonoBehaviour {
public bool socketReady;
public static TcpClient socket;
public static NetworkStream stream;
public static StreamWriter writer;
public static StreamReader reader;
public void ConnectToWorldServer()
{
if (socketReady)
{
return;
}
//Default host and port values;
string host = "127.0.0.1";
int port = 8080;
try
{
socket = new TcpClient(host, port);
stream = socket.GetStream();
writer = new StreamWriter(stream);
reader = new StreamReader(stream);
socketReady = true;
}
catch (Exception e)
{
Debug.Log("Socket error : " + e.Message);
}
}
}
Here is how i send data to the server using my Send function:
public void Send(string header, Dictionary<string, string> data)
{
if (stream.CanRead)
{
socketReady = true;
}
if (!socketReady)
{
return;
}
JsonData SendData = new JsonData();
SendData.header = "1x" + header;
foreach (var item in data)
{
SendData.data.Add(item.Key.ToString(), item.Value.ToString());
}
SendData.connectionId = connectionId;
string json = JsonConvert.SerializeObject(SendData);
var howManyBytes = json.Length * sizeof(Char);
writer.WriteLine(json);
writer.Flush();
Debug.Log("Client World:" + json);
}
As you can see i'm sending the data to the Stream like a string not like a byte array. As far as i know i should send the data as byte array prepending the size of the message and following the message. On the server side i have no clue how i can read that data.
Here is how i read it now(it works for now, but it will not work if i try to send more messages at once):
class WorldServer
{
public List<ServerClient> clients = new List<ServerClient>();
public List<ServerClient> disconnectList;
public List<CharactersOnline> charactersOnline = new List<CharactersOnline>();
public int port = 8080;
private TcpListener server;
private bool serverStarted;
private int connectionIncrementor;
private string mysqlConnectionString = #"server=xxx;userid=xxx;password=xxx;database=xx";
private MySqlConnection mysqlConn = null;
private MySqlDataReader mysqlReader;
static void Main(string[] args)
{
WorldServer serverInstance = new WorldServer();
Console.WriteLine("Starting World Server...");
try
{
serverInstance.mysqlConn = new MySqlConnection(serverInstance.mysqlConnectionString);
serverInstance.mysqlConn.Open();
Console.WriteLine("Connected to MySQL version: " + serverInstance.mysqlConn.ServerVersion + "\n");
}
catch (Exception e)
{
Console.WriteLine("MySQL Error: " + e.ToString());
}
finally
{
if (serverInstance.mysqlConn != null)
{
serverInstance.mysqlConn.Close();
}
}
serverInstance.clients = new List<ServerClient>();
serverInstance.disconnectList = new List<ServerClient>();
try
{
serverInstance.server = new TcpListener(IPAddress.Any, serverInstance.port);
serverInstance.server.Start();
serverInstance.StartListening();
serverInstance.serverStarted = true;
Console.WriteLine("Server has been started on port: " + serverInstance.port);
}
catch (Exception e)
{
Console.WriteLine("Socket error: " + e.Message);
}
new Thread(() =>
{
Thread.CurrentThread.IsBackground = true;
/* run your code here */
while (true)
{
string input = Console.ReadLine();
string[] commands = input.Split(':');
if (commands[0] == "show online players")
{
Console.WriteLine("Showing connections\n");
foreach (CharactersOnline c in serverInstance.charactersOnline)
{
Console.WriteLine("Character name: " + c.characterName + "Character ID: " + c.characterId + "Connection id: " + c.connectionId + "\n");
}
}
continue;
}
}).Start();
while (true)
{
serverInstance.Update();
}
}
private void Update()
{
//Console.WriteLine("Call");
if (!serverStarted)
{
return;
}
foreach (ServerClient c in clients.ToList())
{
// Is the client still connected?
if (!IsConnected(c.tcp))
{
c.tcp.Close();
disconnectList.Add(c);
Console.WriteLine(c.connectionId + " has disconnected.");
CharacterLogout(c.connectionId);
continue;
//Console.WriteLine("Check for connection?\n");
}
else
{
// Check for message from Client.
NetworkStream s = c.tcp.GetStream();
if (s.DataAvailable)
{
StreamReader reader = new StreamReader(s, true);
string data = reader.ReadLine();
if (data != null)
{
OnIncomingData(c, data);
}
}
//continue;
}
}
for (int i = 0; i < disconnectList.Count - 1; i++)
{
clients.Remove(disconnectList[i]);
disconnectList.RemoveAt(i);
}
}
private void OnIncomingData(ServerClient c, string data)
{
Console.WriteLine(data);
dynamic json = JsonConvert.DeserializeObject(data);
string header = json.header;
//Console.WriteLine("Conn ID:" + json.connectionId);
string connId = json.connectionId;
int.TryParse(connId, out int connectionId);
string prefix = header.Substring(0, 2);
if (prefix != "1x")
{
Console.WriteLine("Unknown packet: " + data + "\n");
}
else
{
string HeaderPacket = header.Substring(2);
switch (HeaderPacket)
{
default:
Console.WriteLine("Unknown packet: " + data + "\n");
break;
case "004":
int accountId = json.data["accountId"];
SelectAccountCharacters(accountId, connectionId);
break;
case "005":
int characterId = json.data["characterId"];
getCharacterDetails(characterId, connectionId);
break;
case "006":
int charId = json.data["characterId"];
SendDataForSpawningOnlinePlayers(charId, connectionId);
break;
case "008":
Dictionary<string, string> dictObj = json.data.ToObject<Dictionary<string, string>>();
UpdateCharacterPosition(dictObj, connectionId);
break;
}
}
private bool IsConnected(TcpClient c)
{
try
{
if (c != null && c.Client != null && c.Client.Connected)
{
if (c.Client.Poll(0, SelectMode.SelectRead))
{
return !(c.Client.Receive(new byte[1], SocketFlags.Peek) == 0);
}
return true;
}
else
{
return false;
}
}
catch
{
return false;
}
}
private void StartListening()
{
server.BeginAcceptTcpClient(OnConnection, server);
}
private void OnConnection(IAsyncResult ar)
{
connectionIncrementor++;
TcpListener listener = (TcpListener)ar.AsyncState;
clients.Add(new ServerClient(listener.EndAcceptTcpClient(ar)));
clients[clients.Count - 1].connectionId = connectionIncrementor;
StartListening();
//Send a message to everyone, say someone has connected!
Dictionary<string, string> SendDataBroadcast = new Dictionary<string, string>();
SendDataBroadcast.Add("connectionId", clients[clients.Count - 1].connectionId.ToString());
Broadcast("001", SendDataBroadcast, clients, clients[clients.Count - 1].connectionId);
Console.WriteLine(clients[clients.Count - 1].connectionId + " has connected.");
}
And this is how the server send back data to the client:
private void Send(string header, Dictionary<string, string> data, int cnnId)
{
foreach (ServerClient c in clients.ToList())
{
if (c.connectionId == cnnId)
{
try
{
//Console.WriteLine("Sending...");
StreamWriter writer = new StreamWriter(c.tcp.GetStream());
if (header == null)
{
header = "000";
}
JsonData SendData = new JsonData();
SendData.header = "0x" + header;
foreach (var item in data)
{
SendData.data.Add(item.Key.ToString(), item.Value.ToString());
}
SendData.connectionId = cnnId;
string JSonData = JsonConvert.SerializeObject(SendData);
writer.WriteLine(JSonData);
writer.Flush();
//Console.WriteLine("Trying to send data to connection id: " + cnnId + " data:" + sendData);
}
catch (Exception e)
{
Console.WriteLine("Write error : " + e.Message + " to client " + c.connectionId);
}
}
}
}
Here is my ServerClient class:
public class ServerClient
{
public TcpClient tcp;
public int accountId;
public int connectionId;
public ServerClient(TcpClient clientSocket)
{
tcp = clientSocket;
}
}
Can you please show me how i should modify my Send function on the client to send the data as byte array so i can create "TCP Message Framing" and how should i change my the following part on the server:
foreach (ServerClient c in clients.ToList())
{
// Is the client still connected?
if (!IsConnected(c.tcp))
{
c.tcp.Close();
disconnectList.Add(c);
Console.WriteLine(c.connectionId + " has disconnected.");
CharacterLogout(c.connectionId);
continue;
//Console.WriteLine("Check for connection?\n");
}
else
{
// Check for message from Client.
NetworkStream s = c.tcp.GetStream();
if (s.DataAvailable)
{
StreamReader reader = new StreamReader(s, true);
string data = reader.ReadLine();
if (data != null)
{
OnIncomingData(c, data);
}
}
//continue;
}
}
which is responsible for receving data on the server ?
Is it possible to change only these parts from the Client and on the Server and make it continue to work but this time properly with TCP Message Framing ?
Of course the listener on the client and the Send function of the server i'll remake once i understand how this framing should look like.

Your frames are already defined by cr/lf - so that much already exists; what you need to do is to keep a back buffer per stream - something like a MemoryStream might be sufficient, depending on how big you need to scale; then essentially what you're looking to do is something like:
while (s.DataAvailable)
{
// try to read a chunk of data from the inbound stream
int bytesRead = s.Read(someBuffer, 0, someBuffer.Length);
if(bytesRead > 0) {
// append to our per-socket back-buffer
perSocketStream.Position = perSocketStream.Length;
perSocketStream.Write(someBuffer, 0, bytesRead);
int frameSize; // detect any complete frame(s)
while((frameSize = DetectFirstCRLF(perSocketStream)) >= 0) {
// decode it as text
var backBuffer = perSocketStream.GetBuffer();
string message = encoding.GetString(
backBuffer, 0, frameSize);
// remove the frame from the start by copying down and resizing
Buffer.BlockCopy(backBuffer, frameSize, backBuffer, 0,
(int)(backBuffer.Length - frameSize));
perSocketStream.SetLength(backBuffer.Length - frameSize);
// process it
ProcessMessage(message);
}
}
}

C# Socket: Client Mishandle 'a' as the Client's id

There are two programs that I made that didn't work. There are the server and the client. The server accepts many client by giving a user an ID (starting from 0). The server sends out the command to the specific client based up the server's id. (Example: 200 client are connected to 1 server. The server's selected id is '5', so the server will send the command to all of the client, and the client will ask the server what ID he wants to execute his command on, and if it's '5', that client will execute and send data to the server). The client has many commands, but to create the smallest code with the same error, I only use 1 command (dir). Basically, the server sends the command to the client and if it matches with the client current id and the server current id, it will process the command. By default, the server's current ID is 10. Here are the list of the commands to help the people who wants to answer:
Server Command:
list (Shows all of the users ID connected and the server's current ID) --> Happens on server
dir (request the client to send its dir listing) --> Sent by the client, read by the Server
set (set the server's current id to any number) (example: 'set 4')
Client:
using System;
using System.Speech.Synthesis;
using System.Windows.Forms;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading;
using System.Net.Sockets;
using System.Net;
namespace clientControl
{
class Program
{
public static string directory = #"C:\";
public static int id = -10;
public static Socket sck = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
static void Main(string[] args)
{
Connect();
getSession();
ReadResponse(sck);
}
static byte[] readResponseFunc()
{
long fileSize = 0;
string fileSizeInString = null;
byte[] fileSizeInByteArray = new byte[1024];
int fileSizeLength = sck.Receive(fileSizeInByteArray);
for (int i = 0; i < fileSizeLength; i++)
{
fileSizeInString = fileSizeInString + (char)fileSizeInByteArray[i];
}
try
{
fileSize = Convert.ToInt64(fileSizeInString);
}
catch { Console.WriteLine(fileSizeInString); }
sck.Send(Encoding.ASCII.GetBytes("a"));
byte[] responseUnknown = new byte[1];
sck.Receive(responseUnknown);
if (Encoding.ASCII.GetString(responseUnknown) == "b")
{
byte[] dataInByteArray = new byte[fileSize];
int dataLength = sck.Receive(dataInByteArray);
return dataInByteArray;
}
return Encoding.ASCII.GetBytes("ERROR RESPONSE FUNC");
}
static void getSession()
{
byte[] message_1 = Encoding.ASCII.GetBytes("make_id");
sck.Send(Encoding.ASCII.GetBytes(message_1.Length.ToString()));
byte[] responseUnknown = new byte[1];
if (Encoding.ASCII.GetString(responseUnknown) == "a")
{
sck.Send(Encoding.ASCII.GetBytes("b"));
sck.Send(message_1);
}
byte[] receivedID = readResponseFunc();
id = Convert.ToInt32(Encoding.ASCII.GetString(receivedID));
}
static bool SocketConnected(Socket s)
{
bool part1 = s.Poll(1000, SelectMode.SelectRead);
bool part2 = (s.Available == 0);
if (part1 && part2)
return false;
else
return true;
}
static void ReadResponse(Socket sck)
{
while (true)
{
if (SocketConnected(sck) == true)
{
try
{
string response = Encoding.ASCII.GetString(readResponseFunc());
byte[] message_1 = Encoding.ASCII.GetBytes("get_id");
sck.Send(Encoding.ASCII.GetBytes(message_1.Length.ToString()));
byte[] responseUnknown = new byte[1];
if (Encoding.ASCII.GetString(responseUnknown) == "a")
{
sck.Send(Encoding.ASCII.GetBytes("b"));
sck.Send(message_1);
}
byte[] response_2InByteArray = readResponseFunc();
string response_2 = Encoding.ASCII.GetString(response_2InByteArray);
if (Convert.ToInt32(response_2) == id)
{
if (response == "dir")
{
string resultOfDirring = "Current Directory: " + directory + "\n\n";
string[] folderListingArray = Directory.GetDirectories(directory);
foreach (string dir in folderListingArray)
{
string formed = "DIRECTORY: " + Path.GetFileName(dir);
resultOfDirring = resultOfDirring + formed + Environment.NewLine;
}
string[] fileListingArray = Directory.GetFiles(directory);
foreach (var file in fileListingArray)
{
FileInfo fileInfo = new FileInfo(file);
string formed = "FILE: " + Path.GetFileName(file) + " - FILE SIZE: " + fileInfo.Length + " BYTES";
resultOfDirring = resultOfDirring + formed + Environment.NewLine;
}
byte[] message_11 = Encoding.ASCII.GetBytes(resultOfDirring);
sck.Send(Encoding.ASCII.GetBytes(message_11.Length.ToString()));
byte[] responseUnknown_11 = new byte[1];
if (Encoding.ASCII.GetString(responseUnknown_11) == "a")
{
sck.Send(Encoding.ASCII.GetBytes("b"));
sck.Send(message_11);
}
}
}
else { }
}
catch { if (SocketConnected(sck) == false) { Console.WriteLine("Client Disconnected: " + sck.RemoteEndPoint); break; }; }
}
else if (SocketConnected(sck) == false) { Console.WriteLine("Client Disconnected: " + sck.RemoteEndPoint); break; }
}
}
static void Connect()
{
while (true)
{
try
{
sck.Connect(IPAddress.Parse("127.0.0.1"), 80);
break;
}
catch { }
}
}
}
}
Server:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Net.Sockets;
using System.IO;
using System.Text;
using System.Threading;
namespace serverControl
{
class Program
{
public static int ftpNum = 1;
public static List<int> listOfClient = new List<int>();
public static TcpListener server = new TcpListener(IPAddress.Parse("127.0.0.1"), 80);
public static string message = null;
public static int id = 0;
public static int selected_id = 10;
static void Main(string[] args)
{
server.Start();
Thread startHandlingClientThread = new Thread(startHandlingClient);
startHandlingClientThread.Start();
while (true)
{
Console.Write(":> ");
string rawmessage = Console.ReadLine();
if (rawmessage == "list")
{
Console.WriteLine("SELECTED ID: " + selected_id);
Console.WriteLine("List of Clients ID:");
for (int i = 0; i < listOfClient.Count; i++)
{
Console.WriteLine(listOfClient[i]);
}
message = rawmessage+"PREVENT_REPETITION_IN_COMMAND";
}
else if (rawmessage.Contains("set ")) { int wantedChangeId = Convert.ToInt32(rawmessage.Replace("set ", "")); selected_id = wantedChangeId; message = rawmessage+ "PREVENT_REPETITION_IN_COMMAND"; }
else
{
message = rawmessage;
}
}
}
static byte[] readResponseFunc(Socket sck)
{
long fileSize = 0;
string fileSizeInString = null;
byte[] fileSizeInByteArray = new byte[1024];
int fileSizeLength = sck.Receive(fileSizeInByteArray);
for (int i = 0; i < fileSizeLength; i++)
{
fileSizeInString = fileSizeInString + (char)fileSizeInByteArray[i];
}
fileSize = Convert.ToInt64(fileSizeInString);
sck.Send(Encoding.ASCII.GetBytes("a"));
byte[] responseUnknown = new byte[1];
sck.Receive(responseUnknown);
if (Encoding.ASCII.GetString(responseUnknown) == "b")
{
byte[] dataInByteArray = new byte[fileSize];
int dataLength = sck.Receive(dataInByteArray);
return dataInByteArray;
}
return Encoding.ASCII.GetBytes("ERROR RESPONSE FUNC");
}
static void startHandlingClient()
{
while (true)
{
handleClient(server);
}
}
static void handleClient(TcpListener clientToAccept)
{
Socket sck = clientToAccept.AcceptSocket();
Thread myNewThread = new Thread(() => ReadResponse(sck));
myNewThread.Start();
}
static bool SocketConnected(Socket s)
{
bool part1 = s.Poll(1000, SelectMode.SelectRead);
bool part2 = (s.Available == 0);
if (part1 && part2)
return false;
else
return true;
}
static void ReadResponse(Socket sck)
{
Thread myNewThread = new Thread(() => SendtoClient(sck));
myNewThread.Start();
Thread.Sleep(2000);
while (true)
{
if (SocketConnected(sck) == true)
{
try
{
byte[] dataInByteArray = readResponseFunc(sck);
string response = Encoding.ASCII.GetString(dataInByteArray);
Console.WriteLine("res: " + response);
if (response != "make_id" && response != "get_id") { Console.WriteLine(response); }
if (response == "make_id")
{
Console.WriteLine("Someone wants an ID");
byte[] message_1 = Encoding.ASCII.GetBytes(id.ToString());
listOfClient.Add(id);
// START
sck.Send(Encoding.ASCII.GetBytes(message_1.Length.ToString()));
byte[] responseUnknown = new byte[1];
if (Encoding.ASCII.GetString(responseUnknown) == "a")
{
sck.Send(Encoding.ASCII.GetBytes("b"));
sck.Send(message_1);
}
id++;
}
if (response == "get_id")
{
byte[] message_1 = Encoding.ASCII.GetBytes(selected_id.ToString());
sck.Send(Encoding.ASCII.GetBytes(message_1.Length.ToString()));
byte[] responseUnknown = new byte[1];
if (Encoding.ASCII.GetString(responseUnknown) == "a")
{
sck.Send(Encoding.ASCII.GetBytes("b"));
sck.Send(message_1);
}
}
}
catch { if (SocketConnected(sck) == false) { Console.WriteLine("Client Disconnected: " + sck.RemoteEndPoint); break; }; }
}
else if (SocketConnected(sck) == false) { Console.WriteLine("Client Disconnected: " + sck.RemoteEndPoint); break; }
}
}
static void SendtoClient(Socket sck)
{
string tempmessage = null;
while (true)
{
if (SocketConnected(sck) == true)
{
if (tempmessage != message)
{
if (!message.Contains("PREVENT_REPETITION_IN_COMMAND"))
{
byte[] message_1 = Encoding.ASCII.GetBytes(message);
sck.Send(Encoding.ASCII.GetBytes(message_1.Length.ToString()));
byte[] responseUnknown = new byte[1];
if (Encoding.ASCII.GetString(responseUnknown) == "a")
{
sck.Send(Encoding.ASCII.GetBytes("b"));
sck.Send(message_1);
}
}
tempmessage = message;
}
}
else if (SocketConnected(sck) == false)
{ Console.WriteLine("Client Disconnected: " + sck.RemoteEndPoint); break; }
}
}
}
}
Problem:
The problem is within the GetSession or the ReadResponseFunc function. The client thinks that his ID received by the server is 'a' (it's suppose to be an integer). I don't want a solution that suggest me to use other libs or
the TcpClient class
Bounty:
I'll put up a bounty with no expiry time to those who solve the problem.

The logic in your code is very confusing. My question to you: Why are you sending 'a' and 'b' back and forth between the server and client? Is it some sort of confirmation that the message has been received?
Anyways, throughout the quick tests I've done just now, it seems that the problem is Line 59 of your server:
sck.Send(Encoding.ASCII.GetBytes("a"));
Here's what I figured out during testing:
Server executes.
Client executes.
Client sends server the length of "make_id" (Line 51 of client)
Client waits for a response to return.
Server reads the value and sends back 'a' (Line 59 of server)
You may want to spend some time to straighten out your protocol so it's less confusing and more organized. That would help people like me and you spot bugs much more easily.

The user 'Bobby' has already found your problem. Credits go to him.
I further suggest that you use less threads, as thread synchronisation needs some effort when doing it right: all data that is accessed from different threads must be secured by locks, so that no outdated values remain in the CPU caches. Use .net Monitor from the "threading synchronisation primitives" for that job.
About the threads themselves:
You should have only one thread in the server. This thread takes all clients from a list (secured by Monitor), in which they were added when connection attempts were received. On each client it checks for incoming messages, evaluates them and replies with own messages if needed.
The client also has just one thread, that will loop (dont forget a sleep in the loop or you will have 100% usage of the used CPU core), send messages when desired and wait for replies when messages were sent.
About the messages:
I already gave some proposals in a comment to Bobby's answer. I suggest you create a CMessage class that has a Serialize() and Deserialze() to create a byte array to send from the CMessage members (serializing the content) or vice versa filling the members from the received bytes. You then may use this class in both programs and you'll have common solution.

Multithreading for making http post requests to web service

I want to send multiple HTTP post requests to a Web Service in C# .For example , if n=3 then http post requests from 3 xml files should be made and also the response should be written in a file.Once the first 3 requests are made then the next 3 requests will be made .
So i made the following code but i was getting random outputs at first. But now i am getting either out of index range exception in the inner for loop or Internal server error (500). Plz suggest appropriate changes. I am using .NET4.0
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
using System.Threading;
using System.Xml;
using System.Net;
using System.Threading.Tasks;
namespace ConsoleApplication5
{
class Program
{
static void Main(string[] args)
{
int n = 0;
Console.WriteLine("Enter the number");
string s = Console.ReadLine();
int.TryParse(s, out n);
string path = "C:\\";
string[] files = null;
files = Directory.GetFiles(path, "*.xml", SearchOption.TopDirectoryOnly);
List<Task> tasks = new List<Task>(files.Length);
for (int i = 0; i < files.Length; i += n)
{
for (int j = 0; j < n; j++)
{
int x = i + j;
if (x < files.Length && files[x] != null)
{
Task t = new Task(() => function(files[x]));
t.Start();
tasks.Add(t);
}
}
if (tasks.Count > 0)
{
Task.WaitAll(tasks.ToArray(), Timeout.Infinite); // or less than infinite
tasks.Clear();
}
}
}
public static void function(string temp)
{
XmlDocument doc = new XmlDocument();
doc.Load(temp);
HttpWebRequest request = (HttpWebRequest)WebRequest.Create("http://10.76.22.135/wpaADws/ADService.asmx");
request.ContentType = "text/xml;charset=\"utf-8\"";
request.Accept = "text/xml";
request.Method = "POST";
Stream stream = request.GetRequestStream();
doc.Save(stream);
stream.Close();
HttpWebResponse response = (HttpWebResponse)request.GetResponse();
using (StreamReader rd = new StreamReader(response.GetResponseStream()))
{
string soapResult = rd.ReadToEnd();
doc.LoadXml(soapResult);
File.WriteAllText(temp, doc.DocumentElement.InnerText);
//XmlTextWriter xml=new XmlTextWriter(
Console.WriteLine(soapResult);
Console.ReadKey();
}
}
}
}

This code works .
Explaination :
Firstly the user gives the source and destination paths for the .xml files.
Directory.getFiles() helps us to get the .xml files in the string array .
(we have to pass .xml as a parameter) .
SO now what basically happens is for each file we get at the source pat , a thread is created .
But say if the user wants to send "n" requests at a time , then n threads are created at a time.
And the next set of threads are not created unless the previous threads are finished executing.
This is ensured by thread.Join().
And after a request is made to the web service , we get the response by getResponse() and the response is written in .xml files which are stored at the destination paths.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
using System.Threading;
using System.Xml;
using System.Net;
namespace ConsoleApplication4
{
class Program
{
int flag = 1;
string destination;
string source;
static void Main(string[] args)
{
Console.ForegroundColor = ConsoleColor.Red;
Console.WriteLine("**************************** Send HTTP Post Requests **************************");
int n = 0;
Program p = new Program();
Console.WriteLine("Enter the number of requests you want to send at a time");
string s = Console.ReadLine();
int.TryParse(s, out n);
Console.WriteLine("Enter Source");
p.source = Console.ReadLine();
Console.WriteLine("Enter Destination");
p.destination = Console.ReadLine();
string[] files = null;
files = Directory.GetFiles(p.source, "*.xml", SearchOption.TopDirectoryOnly);
Thread[] thread = new Thread[files.Length];
int len = files.Length;
for (int i = 0; i<len; i+=n)
{
int x = i;
//Thread.Sleep(5000);
for (int j = 0; j < n && x < len; j++)
{
var localx = x;
thread[x] = new Thread(() => function(files[localx], p));
thread[x].Start();
Thread.Sleep(50);
//thread[x].Join();
x++;
}
int y = x - n;
for (; y < x; y++)
{
int t = y;
thread[t].Join();
}
}
// thread[0] = new Thread(() => function(files[0]));
//thread[0].Start();
Console.ReadKey();
}
public static void function(string temp,Program p)
{
XmlDocument doc = new XmlDocument();
doc.Load(temp);
string final_d=p.destination + "response " + p.flag + ".xml";
p.flag++;
HttpWebRequest request = (HttpWebRequest)WebRequest.Create("http://10.76.22.135/wpaADws/ADService.asmx");
request.ContentType = "text/xml;charset=\"utf-8\"";
request.Accept = "text/xml";
request.Method = "POST";
Stream stream = request.GetRequestStream();
doc.Save(stream);
stream.Close();
HttpWebResponse response = (HttpWebResponse)request.GetResponse();
using (StreamReader rd = new StreamReader(response.GetResponseStream()))
{
string soapResult = rd.ReadToEnd();
doc.LoadXml(soapResult);
File.WriteAllText(final_d, doc.DocumentElement.InnerText);
//XmlTextWriter xml=new XmlTextWriter(
Console.WriteLine(soapResult);
//Console.ReadKey();
}
}
}
}

The IndexOutOfRangeException you experienced in your original post was due to the improper index handling on the last batch of files you were processing. That last batch can be incomplete and you treated that as a regular batch of set size
(n=3 in your post)
Since you're moving to TPL and Tasks, I suggest Parallel Programming with Microsoft .NET, and the pipeline pattern which seems very appropriate to your scenario. You can harness the power of concurrent collections and the producer/consumer pattern together with the pipeline, like below. BlockingCollection ensures concurrent adding of items and the BlockingCollection.GetConsumingEnumerable call produces a consuming blocking enumerator for your collection.
const int BUFFER_SIZE = 3; // no concurrent items to process
const string XML_FOLDER_PATH = "<whatever>";
public static void Pipeline()
{
var bufferXmlFileNames = new BlockingCollection<string>(BUFFER_SIZE);
var bufferInputXmlDocuments = new BlockingCollection<XmlDocument>(BUFFER_SIZE);
var bufferWebRequests = new BlockingCollection<HttpWebRequest>(BUFFER_SIZE);
var bufferSoapResults = new BlockingCollection<string>(BUFFER_SIZE);
var f = new TaskFactory(TaskCreationOptions.LongRunning, TaskContinuationOptions.None);
// Stage 1: get xml file paths
var stage1 = f.StartNew(() => {
try
{
foreach (var phrase in Directory.GetFiles(XML_FOLDER_PATH, "*.xml", SearchOption.TopDirectoryOnly))
{ // build concurrent collection
bufferXmlFileNames.Add(phrase);
}
}
finally
{ // no more additions acceptedin
bufferXmlFileNames.CompleteAdding();
}
});
// Stage 2: ProduceInputXmlDocuments(bufferXmlFileNames, bufferInputXmlDocuments)
var stage2 = f.StartNew(() => {
try
{
foreach (var xmlFileName in bufferXmlFileNames.GetConsumingEnumerable())
{
XmlDocument doc = new XmlDocument();
doc.Load(xmlFileName);
bufferInputXmlDocuments.Add(doc);
}
}
finally
{
bufferInputXmlDocuments.CompleteAdding();
}
});
// Stage 3: PostRequests(BlockingCollection<XmlDocument> xmlDocs, BlockingCollection<HttpWebRequest> posts)
var stage3 = f.StartNew(() => {
try
{
foreach (var xmlDoc in bufferInputXmlDocuments.GetConsumingEnumerable())
{
HttpWebRequest request = (HttpWebRequest)WebRequest.Create("http://10.76.22.135/wpaADws/ADService.asmx");
request.ContentType = "text/xml;charset=\"utf-8\"";
request.Accept = "text/xml";
request.Method = "POST";
//
Stream stream = request.GetRequestStream();
xmlDoc.Save(stream);
stream.Close();
//
bufferWebRequests.Add(request);
}
}
finally
{
bufferWebRequests.CompleteAdding();
}
});
// Stage 4: ProcessResponses(bufferWebRequests, bufferSoapResults)
var stage4 = f.StartNew(() =>
{
try
{
foreach (var postRequest in bufferWebRequests.GetConsumingEnumerable())
{
HttpWebResponse response = (HttpWebResponse)postRequest.GetResponse();
using (StreamReader rd = new StreamReader(response.GetResponseStream()))
{
string soapResult = rd.ReadToEnd();
bufferSoapResults.Add(soapResult);
}
}
}
finally
{
bufferSoapResults.CompleteAdding();
}
});
// stage 5: update UI
var stage5 = f.StartNew(() =>
{
foreach (var soapResult in bufferSoapResults.GetConsumingEnumerable())
{
Console.WriteLine(soapResult);
}
});
// display blocking collection load state,
// the number of elements in each blocking collection of the pipeline stages
// you can supress this call completely, because it is informational only
var stageDisplay = f.StartNew(
() =>
{
while (true)
{
Console.WriteLine("{0,10} {1,10} {2,10} {3,10}", bufferXmlFileNames.Count, bufferInputXmlDocuments.Count, bufferWebRequests.Count, bufferSoapResults.Count);
//check last stage completion
if (stage5.IsCompleted)
return;
}
}
);
Task.WaitAll(stage1, stage2, stage3, stage4, stage5); //or
//Task.WaitAll(stage1, stage2, stage3, stage4, stage5, stageDisplay);
}

How about using tasks like this:
List<Task> tasks = new List<Task>(n);
for (int i = 0; i < files.Length; i += n)
{
for (int j = 0; j < n; j++)
{
int x = i + j;
if (x < files.Length && files[x] != null)
{
Task t = new Task(() => function(files[x]));
t.Start();
tasks.Add(t);
}
}
if (tasks.Count > 0)
{
Task.WaitAll(tasks.ToArray(), Timeout.Infinite); // or less than infinite
tasks.Clear();
}
}
I tried to be a little tidier on the indexing...
Also, note that the int x = i + j; in the inner loop is important due to how C# captures variables for the lambda.
If the problem is tracing down indexing arithmetic, maybe use indexing variables with meaningful names?
List<Task> tasks = new List<Task>(taskCount);
for (int filesIdx = 0; filesIdx < files.Length; filesIdx += taskCount)
{
for (int tasksIdx = 0; tasksIdx < taskCount; tasksIdx++)
{
int index = filesIdx + tasksIdx;
if (index < files.Length && files[index] != null)
{
Task task = new Task(() => function(files[index]));
task.Start();
tasks.Add(task);
}
}
if (tasks.Count > 0)
{
Task.WaitAll(tasks.ToArray(), Timeout.Infinite); // or less than infinite
tasks.Clear();
}
}

Add link to rich text box that starts a process (RDP)

I'm trying to add a clickable link to a rich text box that says something like "Start RDP" so when a user clicks on it, it will start windows remote desktop and use put the machine name in the box for you. Here is my code so far, It searchs Active Directory for a computer name that the user enters, pings the machine and if it is online, show its status in another textbox.
private void btnAd_Click(object sender, EventArgs e)
{
var adsb = new StringBuilder();
var mssb = new StringBuilder();
DirectoryEntry de = new DirectoryEntry();
de.Path = "LDAP://dc=Domain.org";
try
{
string wildcard = "*";
string adser = wildcard + txtAd.Text + wildcard;
DirectorySearcher ser = new DirectorySearcher();
ser.SizeLimit = System.Int32.MaxValue;
ser.PageSize = System.Int32.MaxValue;
ser.Filter = "(&(ObjectCategory=computer)(name=" + adser + "))"; //Only allows Computers to be returned in results.
SearchResultCollection results = ser.FindAll();
if (String.IsNullOrEmpty(txtcomputers.Text)) //if the textbox is empty, write ad search results to textbox
{
foreach (SearchResult res in results)
{
string[] temp = res.Path.Split(','); //temp[0] would contain the computer name ex: cn=computerName,..
adsb.AppendLine(temp[0].Substring(10));//returns everything after LDAP://CN= until end of temp[0].
if (Ping(temp[0].Substring(10)))
{
mssb.AppendLine(temp[0].Substring(10) + "....Online");
}
else
{
mssb.AppendLine(temp[0].Substring(10) + "....Offline");
}
}
rtbComputerstatus.Text = mssb.ToString();
txtcomputers.Text = adsb.ToString();
}
else //Add items to textbox if there are already items present.
{
txtcomputers.AppendText(Environment.NewLine);
rtbComputerstatus.AppendText(Environment.NewLine);
foreach (SearchResult res in results)
{
string[] temp = res.Path.Split(',');
adsb.AppendLine(temp[0].Substring(10));
txtcomputers.AppendText(adsb.ToString());
if (Ping(temp[0].Substring(10)))
{
mssb.AppendLine(temp[0].Substring(10) + "....Online......");
}
else
{
mssb.AppendLine(temp[0].Substring(10) + "....Offline");
}
rtbComputerstatus.AppendText(mssb.ToString());
}
}
//trims spaces
this.txtcomputers.Text = this.txtcomputers.Text.Trim();
txtcomputers.CharacterCasing = CharacterCasing.Upper;
//color items
HighlightPhrase(rtbComputerstatus, "Online",Color.Green);
HighlightPhrase(rtbComputerstatus, "Offline", Color.Red);
HighlightPhrase(rtbComputerstatus, "RDP", Color.Blue);
}
catch (Exception ex)
{
MessageBox.Show(ex.ToString());
}
finally
{
de.Dispose();//Clean up resources
}
}
// color method
static void HighlightPhrase(RichTextBox box, string phrase, Color color)
{
int pos = box.SelectionStart;
string s = box.Text;
for (int ix = 0; ; )
{
int jx = s.IndexOf(phrase, ix, StringComparison.CurrentCultureIgnoreCase);
if (jx < 0) break;
box.SelectionStart = jx;
box.SelectionLength = phrase.Length;
box.SelectionColor = color;
ix = jx + 1;
}
box.SelectionStart = pos;
box.SelectionLength = 0;
}
//ping method
public static bool Ping(string hostName)
{
bool result = false;
try
{
Ping pingSender = new Ping(); PingOptions options = new PingOptions();
// Use the default Ttl value which is 128,
// but change the fragmentation behavior.
options.DontFragment = true;
// Create a buffer of 32 bytes of data to be transmitted.
string data = "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa";
byte[] buffer = Encoding.ASCII.GetBytes(data);
int timeout = 120;
PingReply reply = pingSender.Send(hostName, timeout, buffer, options); if (reply.Status == IPStatus.Success)
{
result = true;
}
else
{
result = false;
}
}
catch
{
result = false;
}
return result;
}
Any suggestions ? I've tried a few different things but can't seem to get it working.
Thanks !

There is an article published on Codeproject, describing the solution that you are looking for: link
Hope this will help. Rgds, AB