Develop Reference

Send data to specific client from another client with a server in middle[C#]

I have searched everywhere but couldn't find as they are all answering to send message to all clients. What I want to achieve is multiple clients request to server to request data from another client and other client sends data to server telling it that data is for requesting client and so. I don't know how to achieve this. I'm new to this.
What I want to achieve:
I have tried with Data sending client to listen and requesting client to connect to it and transfer data. I have achieved this on local network but to make it work online it needs port forwarding and my user will be a lot of different people so port forwarding is not possible for every user. So I can rent a server which will act as a center of transfer. I programmed a test server in console which will listen to a server IP:port X and accept new clients and their data on port X and forward it to server IP:port Y but what this does is send data to all clients on port Y. I cannot send it to clients public ip address directly for obvious reasons. I understand that all the requesting clients are connected to port Y but I cannot create and assign new ports to all the clients interacting. So I want a way to determine how to request and receive the data without the need of assigning or creating new ports to different clients on same server.
What I have tried:
Server code
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Net;
using System.Net.Sockets;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
namespace Test___server
{
class server
{
public static string serverIP = "192.168.0.102";
static void Main(string[] args)
{
Thread listenSendingThread = new Thread(listenSending);
listenSendingThread.IsBackground = true;
listenSendingThread.Start();
Thread listenReceivingThread = new Thread(listenReceiving);
listenReceivingThread.IsBackground = true;
listenReceivingThread.Start();
Console.ReadKey();
}
public static List<TcpClient> listSending = new List<TcpClient>();
public static List<TcpClient> listReceiving = new List<TcpClient>();
public static TcpClient clientSending = null;
private static void listenSending()
{
TcpListener listenerSending = new TcpListener(IPAddress.Parse(serverIP), 5319);
listenerSending.Start();
Console.WriteLine("Server listening to " + serverIP + ":5319");
while(true)
{
clientSending = listenerSending.AcceptTcpClient();
listSending.Add(clientSending);
Console.WriteLine("Sender connection received from " + clientSending.Client.RemoteEndPoint);
}
}
private static void send()
{
StreamWriter sw = new StreamWriter(clientSending.GetStream());
sw.WriteLine(message);
sw.Flush();
Console.WriteLine("Message sent!");
}
public static string message = string.Empty;
private static void listenReceiving()
{
TcpListener listener = new TcpListener(IPAddress.Parse(serverIP), 0045);
listener.Start();
Console.WriteLine("Server listening to " + serverIP + ":0045");
while (true)
{
TcpClient client = listener.AcceptTcpClient();
listReceiving.Add(client);
Console.WriteLine("Receiver connection received from " + client.Client.RemoteEndPoint);
StreamReader sr = new StreamReader(client.GetStream());
message = sr.ReadLine();
send();
}
}
}
}
Requesting client code
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace Test____admin
{
class admin
{
static void Main(string[] args)
{
Console.WriteLine("Begin");
string serverIP = "192.168.0.102";
System.Net.Sockets.TcpClient clientSocket = new System.Net.Sockets.TcpClient();
clientSocket.Connect(serverIP, );
Console.WriteLine("Connected");
while (true)
{
Console.WriteLine("Reading");
StreamReader sr = new StreamReader(clientSocket.GetStream());
Console.WriteLine("Message: " + sr.ReadLine());
}
}
}
}
Request satisfying client code
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Net.Sockets;
using System.Text;
using System.Threading.Tasks;
namespace Test___client
{
class client
{
public static string serverIP = "192.168.0.102";
static void Main(string[] args)
{
clientConnect();
}
private static void clientConnect()
{
try
{
TcpClient client = new TcpClient(serverIP, 0045);
StreamWriter sw = new StreamWriter(client.GetStream());
sw.WriteLine("Karan!");
sw.Flush();
}
catch (Exception ex)
{
Console.WriteLine(ex.ToString());
}
}
}
}

You are using a very low-level API, and doing it the right way is challenging. Instead, try YARP as a reverse proxy. The requesting client should notify the reverse proxy about the desired destination client. One option is sending the destination client name in the request header. You will also need to split a single server request into multiple client requests, then merge their responses into a single one. You can achieve it by implementing Transphorms.
I'm not sure this approach applies to your situation because clients should implement server API using REST, Grpc or any other supported technology.

error CS1022: Type or namespace definition, or end-of-file expected

I'm creating a messaging application for andriod/ios, but I am completely new to c# and networking, I've followed the first steps of a simple socket tutorial to get me started in networking (https://www.youtube.com/watch?v=KxdOOk6d_I0) but I get the error:
error "CS1022: Type or namespace definition, or end-of-file expected".
I'm assuming that it has something to do with the namespace because im new to c# and don't actually understand what the namespace does, but my compiler says there are no errors (I'm using visual studio code if that makes a difference) but it may be something else.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Net.Sockets;
namespace server_test
{
class program
{
static void main(string[] args)
{
IPAdress ip = Dns.GetHostEntry("localhost").AdressList[0];
TcpListener server = new TcpListener(ip, 8080);
TcpClient client = default(TcpClient);
try
{
server.Start();
Console.WriteLine("server started...");
Console.ReadLine();
}catch (Exception ex)
{
Console.WriteLine(ex.ToString());
Console.ReadLine();
}
}
}
}
it should say server started..." or throw up an exeption but this is what im getting every time:
[Running] mono "C:\Users\Aidan\AppData\Roaming\Code\User\cs-script.user\cscs.exe" "d:!computer science!!NEA!\test stuff\networking\server_test\program.cs"
Error: Specified file could not be compiled.
csscript.CompilerException: d:!computer science!!NEA!\test stuff\networking\server_test\program.cs(7,127): error CS1513: } expected
d:!computer science!!NEA!\test stuff\networking\server_test\program.cs(37,1): error CS1022: Type or namespace definition, or end-of-file expected
at csscript.CSExecutor.ProcessCompilingResult (System.CodeDom.Compiler.CompilerResults results, System.CodeDom.Compiler.CompilerParameters compilerParams, CSScriptLibrary.ScriptParser parser, System.String scriptFileName, System.String assemblyFileName, System.String[] additionalDependencies) [0x00102] in :0
at csscript.CSExecutor.Compile (System.String scriptFileName) [0x0080d] in :0
at csscript.CSExecutor.ExecuteImpl () [0x005a1] in :0
[Done] exited with code=1 in 1.795 seconds

both answers are correct.
System.Net using was missing.
There was a typo in addresslist.
One more problem was - The main function should be spelled as "Main" with capital M.
Full program:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Net.Sockets;
using System.Net;
namespace server_test
{
class program
{
static void Main(string[] args)
{
IPAddress ip = Dns.GetHostEntry("localhost").AddressList[0];
TcpListener server = new TcpListener(ip, 8080);
TcpClient client = default(TcpClient);
try
{
server.Start();
Console.WriteLine("server started...");
Console.ReadLine();
}
catch (Exception ex)
{
Console.WriteLine(ex.ToString());
Console.ReadLine();
}
}
}
}

You are missing namespace import.
Add
using System.Net;
and fix the typo AdressList to AddressList

The error shows The file could not be compiled. So, most probably it's compiler error. I guess below if it's not a typo, the spelling of ipaddress missing a d and so thus AddressList.
IPAddress ip = Dns.GetHostEntry("localhost").AddressList[0];

How can i scan and list all connected devices to my network wireless, i'm getting exception?

My pc is connected to the router of the network i want to scan but the not wireless the pc is connected with a cable to the router.
But my android device is connected to the network wireless.
So in logic in this case the results in the list should be my pc and my android device.
This is what i'm using now managed wifi api:
managed wifi api
This is my code:
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using NativeWifi;
namespace ScanWifi
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
WlanClient client = new WlanClient();
try
{
foreach (WlanClient.WlanInterface wlanIface in client.Interfaces)
{
Wlan.WlanBssEntry[] wlanBssEntries = wlanIface.GetNetworkBssList();
foreach (Wlan.WlanBssEntry network in wlanBssEntries)
{
int rss = network.rssi;
byte[] macAddr = network.dot11Bssid;
string tMac = "";
for (int i = 0; i < macAddr.Length; i++)
{
tMac += macAddr[i].ToString("x2").PadLeft(2, '0').ToUpper();
}
listView1.Items.Add("Found network with SSID {0}." + System.Text.ASCIIEncoding.ASCII.GetString(network.dot11Ssid.SSID).ToString());
listView1.Items.Add("Signal: {0}%."+ network.linkQuality);
listView1.Items.Add("BSS Type: {0}."+ network.dot11BssType);
listView1.Items.Add("MAC: {0}.", tMac);
listView1.Items.Add("RSSID:{0}", rss.ToString());
}
Console.ReadLine();
}
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
}
private void Form1_Load(object sender, EventArgs e)
{
}
}
}
When running the program i'm exception on WlanApi.cs on the line:
Wlan.ThrowIfError(
Wlan.WlanOpenHandle(Wlan.WLAN_CLIENT_VERSION_XP_SP2, IntPtr.Zero, out negotiatedVersion, out clientHandle));
System.ComponentModel.Win32Exception' occurred in ManagedWifi.dll
The service has not been started

For Windows 10, the service "WLAN AutoConfig" must be started for WlanClient to work. This service should be started automatically on a computer which has a WiFi adapter present. On a computer such as a desktop which does not have a WiFi adapter, the service startup type is probably Manual and not started; you can start it anyway and WlanClient should no longer throw any exceptions, but without a WiFi adapter, it won't see any interfaces, so you won't be able to get a list of networks.

According to the documentation of the [WlanOpenHandle ][1] function, the problem is that the Wireless Zero Configuration (WZC) service is not started on your machine:
WlanOpenHandle will return an error message if the Wireless Zero Configuration (WZC) service has not been started or if the WZC service is not responsive.
However, depending on your platform, it might also might be the case that you are simply passing the wrong parameters to the WlanOpenHandle function. Have you tried passing Wlan.WLAN_CLIENT_VERSION_LONGHORN as the first parameter?

400 Bad Request (Invalid Host) using simple webserver in C#

I've got a small C# console app to work as a webserver. It responds well on the NAT with devices in the same network, but when I try to access it in a browser from the external IP i get a 400.
The router is configured to port forward, otherwise I get a 404.
localhost:8888/test works fine.
also 192.168.0.x:8888/test for any device.
xxx.xxx.xxx.xxx:8888/test fails with HTTP Error 400. The request hostname is invalid.
Any suggestions?
using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Text;
using System.Threading.Tasks;
namespace httpsrv
{
class Program
{
static void Main(string[] args)
{
WebServer ws = new WebServer(SendResponse, "http://localhost:8888/test/");
ws.Run();
Console.WriteLine("Pi server started");
Console.ReadKey();
ws.Stop();
}
public static string SendResponse(HttpListenerRequest request)
{
return string.Format("<HTML><BODY>Hosted from rasp. pi!<br>{0}</BODY></HTML>", DateTime.Now);
}
}
}
Webserver class:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
namespace httpsrv
{
public class WebServer
{
private readonly HttpListener _listener = new HttpListener();
private readonly Func<HttpListenerRequest, string> _responderMethod;
public WebServer(string[] prefixes, Func<HttpListenerRequest, string> method)
{
if (!HttpListener.IsSupported)
throw new NotSupportedException(
"Needs Windows XP SP2, Server 2003 or later.");
if (prefixes == null || prefixes.Length == 0)
throw new ArgumentException("prefixes");
if (method == null)
throw new ArgumentException("method");
foreach (string s in prefixes)
_listener.Prefixes.Add(s);
_responderMethod = method;
_listener.Start();
}
public WebServer(Func<HttpListenerRequest, string> method, params string[] prefixes)
: this(prefixes, method) { }
public void Run()
{
ThreadPool.QueueUserWorkItem((o) =>
{
Console.WriteLine("Webserver running...");
try
{
while (_listener.IsListening)
{
ThreadPool.QueueUserWorkItem((c) =>
{
var ctx = c as HttpListenerContext;
try
{
string rstr = _responderMethod(ctx.Request);
byte[] buf = Encoding.UTF8.GetBytes(rstr);
ctx.Response.ContentLength64 = buf.Length;
ctx.Response.OutputStream.Write(buf, 0, buf.Length);
}
catch { }
finally
{
ctx.Response.OutputStream.Close();
}
}, _listener.GetContext());
}
}
catch { }
});
}
public void Stop()
{
_listener.Stop();
_listener.Close();
}
}
}

I had this issue on ubuntu when using self hosted OWIN and c#.
I fixed it by setting the base address set inside my .exe to
http://*:80
instead of
http://192.168.1.1:80

This
WebServer ws = new WebServer(SendResponse, "http://*:80/");
plus starting application (or command prompt / Visual Studio) with 'Run as administrator' mode worked great!

Either your DNS or name resolution is bad.
There are no routes to forward that traffic to your web server
Check your port forwarding you should be forwarding port 8888 to the internal IP
Last but not least check your firewall, it should allow port 8888
Looking at your code, it seems you are hard coding the request, make that a variable so that you can change it on the fly

Had similar issue as #sean-bradley - but on .net.
This worked great:
WebServer ws = new WebServer(SendResponse, "http://+:80/");

SharpSVN connection rate limit to localhost?

We use SharpSVN to programmatically access SVN repositories. Now we have the problem that the access to local repositories via svn:// or http:// urls is very slow - every access needs at least one second, and our app needs to fetch a bunch of properties and directory listings.
We could reproduce the problem on two different machines, both are Windows 7 32 bit and are in the same domain. The SVN servers are VisualSVN 2.1.9 for http:// urls and the CollabNet 1.6.17 for svn:// urls. It appears for connections via "localhost" and via the host name. It appears in our C# application, as well as a small testbed app using IronPython and when calling the SharpSvn svn.exe command.
This problem does not happen when accessing when accessing remote repositories (Both a linux and a windows XP server) - here, each access is between 0.01 and 0.08 secs, which is expected due to network latency. The Problem also does not happen when acessing the local repositories via file:// urls or when accessing the repositories via "native" svn command line tools from CollabNet.
Now my question is: Has Windows 7 or .NET or SharpSVN some built-in limit which only applies to localhost connections?
(Addition: I now found out that this limit also applies when connecting via a small C# test program using System.Net.Sockets.TcpClient:
Server:
using System;
using System.IO;
using System.Net;
using System.Net.Sockets;
namespace TcpSpeedServer
{
class Program
{
public static void Main()
{
Int32 port = 47011;
IPAddress localAddr = IPAddress.Parse("127.0.0.1");
var server = new TcpListener(localAddr, port);
server.Start();
Console.WriteLine("Listening on {0} : {1}", localAddr, port);
ulong count = 0;
// Enter the listening loop.
while(true)
{
using (var client = server.AcceptTcpClient()) {
Console.WriteLine("Connected: {0} {1}!", count, client.Client.RemoteEndPoint);
count += 1;
using (var stream = client.GetStream()) {
using (StreamWriter writer = new StreamWriter(stream))
using (StreamReader reader = new StreamReader(stream))
{
string query = reader.ReadLine();
writer.WriteLine("GET / HTTP/1.0");
writer.WriteLine();
writer.Flush();
}
}
}
}
}
}
}
Client:
using System;
using System.Collections.Generic;
using System.IO;
using System.Net.Sockets;
using System.Threading;
namespace TcpSpeedTest
{
class Program
{
const bool ASYNC = false;
static DateTime s_now;
public static void Main(string[] args)
{
var liste = new List<object>();
s_now = DateTime.Now;
for (int i=0; i < 100; i += 1) {
if (ASYNC)
ThreadPool.QueueUserWorkItem(connect, i);
else
connect(i);
}
Console.WriteLine("outer: " + (DateTime.Now - s_now));
Console.ReadLine();
}
private static void connect(object i)
{
DateTime now = DateTime.Now;
using (TcpClient client = new TcpClient("localhost", 47011))
{
var stream = client.GetStream();
using (StreamWriter writer = new StreamWriter(stream))
using (StreamReader reader = new StreamReader(stream))
{
writer.WriteLine("GET / HTTP/1.0");
writer.WriteLine();
writer.Flush();
string result = reader.ReadLine();
}
}
Console.WriteLine(string.Format("inner: {0} - {1} - {2}", i, DateTime.Now - now, DateTime.Now - s_now));
}
}
}
So this problem seems not to be subversion specific.)
Addition2: When running the client under Mono 2.10 for windows, the problem does not appear. So it seems to be specific to .NET framework.
Addition3: It seems to be an IPv6 related problem. The server only listens on IPv4, but the hostname also resolves to IPv6. Now it seems that the OS code internally tries the IPv6 connection, and after getting the connection reset, waits 1 sec before falling back to IPv4. And this game is repeated for every single connection attempt. http://msdn.microsoft.com/en-us/library/115ytk56.aspx documents that for TcpClient (thanks to Andreas Johansson from the MSDN forums for the hint!), and it seems that the APR used by Apache internally uses a similar mechanism.

Addition 3 is also the solution to your problem. To fix this, either make DNS/hosts file only resolve to an IPv4 address, or make the IPv6 server(s) work.
You can enter in C:\Windows\System32\drivers\etc\hosts something like:
127.0.0.1 localhost-ipv4
And then use that name to connect.
You can also make svnserve listen to IPv6 addresses. A quick search for svnserve options [revealed][1] that it defaults to IPv6, so in its startup parameters is probably a --listen-host. Try removing that, or when it's not present forcing it to run at IPv6.
The same can be done for the Apache webserver:
Listen 0.0.0.0:80
Listen [::]:80