Multi client in server - websocket C#

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how are you? I hope that you are good, I have a question, how can I do to the server consume multi clients? I put all my code

Server

C#

using System;
using System.Net;
using System.Net.Sockets;
using System.Text;
using System.Text.RegularExpressions;

namespace Consola
{
    internal class Program
    {
        static void Main(string[] args)
        {
            string ip = "127.0.0.1";
            int port = 8080;
            var server = new TcpListener(IPAddress.Parse(ip), port);

            server.Start();
            Console.WriteLine("Server has started on {0}:{1}, Waiting for a connection…", ip, port);

            TcpClient client = server.AcceptTcpClient();
            Console.WriteLine("A client connected.");

            NetworkStream stream = client.GetStream();

            // enter to an infinite cycle to be able to handle every change in stream
            while (true)
            {
                while (!stream.DataAvailable) ;
                while (client.Available < 3) ; // match against "get"

                byte[] bytes = new byte[client.Available];
                stream.Read(bytes, 0, client.Available);
                string s = Encoding.UTF8.GetString(bytes);

                if (Regex.IsMatch(s, "^GET", RegexOptions.IgnoreCase))
                {
                    Console.WriteLine("=====Handshaking from client=====\n{0}", s);

                    // 1. Obtain the value of the "Sec-WebSocket-Key" request header without any leading or trailing whitespace
                    // 2. Concatenate it with "258EAFA5-E914-47DA-95CA-C5AB0DC85B11" (a special GUID specified by RFC 6455)
                    // 3. Compute SHA-1 and Base64 hash of the new value
                    // 4. Write the hash back as the value of "Sec-WebSocket-Accept" response header in an HTTP response
                    string swk = Regex.Match(s, "Sec-WebSocket-Key: (.*)").Groups[1].Value.Trim();
                    string swka = swk + "258EAFA5-E914-47DA-95CA-C5AB0DC85B11";
                    byte[] swkaSha1 = System.Security.Cryptography.SHA1.Create().ComputeHash(Encoding.UTF8.GetBytes(swka));
                    string swkaSha1Base64 = Convert.ToBase64String(swkaSha1);

                    // HTTP/1.1 defines the sequence CR LF as the end-of-line marker
                    byte[] response = Encoding.UTF8.GetBytes(
                        "HTTP/1.1 101 Switching Protocols\r\n" +
                        "Connection: Upgrade\r\n" +
                        "Upgrade: websocket\r\n" +
                        "Sec-WebSocket-Accept: " + swkaSha1Base64 + "\r\n\r\n");

                    stream.Write(response, 0, response.Length);
                }
                else
                {
                    bool fin = (bytes[0] & 0b10000000) != 0,
                        mask = (bytes[1] & 0b10000000) != 0; // must be true, "All messages from the client to the server have this bit set"
                    int opcode = bytes[0] & 0b00001111, // expecting 1 - text message
                        offset = 2;
                    ulong msglen = (ulong)(bytes[1] & 0b01111111);

                    if (msglen == 126)
                    {
                        // bytes are reversed because websocket will print them in Big-Endian, whereas
                        // BitConverter will want them arranged in little-endian on windows
                        msglen = BitConverter.ToUInt16(new byte[] { bytes[3], bytes[2] }, 0);
                        offset = 4;
                    }
                    else if (msglen == 127)
                    {
                        // To test the below code, we need to manually buffer larger messages — since the NIC's autobuffering
                        // may be too latency-friendly for this code to run (that is, we may have only some of the bytes in this
                        // websocket frame available through client.Available).
                        msglen = BitConverter.ToUInt64(new byte[] { bytes[9], bytes[8], bytes[7], bytes[6], bytes[5], bytes[4], bytes[3], bytes[2] }, 0);
                        offset = 10;
                    }

                    if (msglen == 0)
                    {
                        Console.WriteLine("msglen == 0");
                    }
                    else if (mask)
                    {
                        byte[] decoded = new byte[msglen];
                        byte[] masks = new byte[4] { bytes[offset], bytes[offset + 1], bytes[offset + 2], bytes[offset + 3] };
                        offset += 4;

                        for (ulong i = 0; i < msglen; ++i)
                            decoded[i] = (byte)(bytes[(ulong)offset + i] ^ masks[i % 4]);

                        string text = Encoding.UTF8.GetString(decoded);
                        Console.WriteLine("{0}", text);
                    }
                    else
                        Console.WriteLine("mask bit not set");

                    Console.WriteLine();
                }
            }
        }
    }
}

Client

HTML

<!DOCTYPE html>
<html lang="en">
<head>
    <link href="Content/bootstrap.min.css" type="text/css" rel="stylesheet" />    
    <script src="Scripts/jquery-3.6.1.min.js" type="text/javascript"></script>    
</head>

<body>
    <div class="card">
        <div class="card-header">
            <h2>Prueba simple de WebSocket</h2>
        </div>
        <div class="card-body">
            <p>
                <textarea cols="60" rows="6" id="cajadetexto"></textarea>
            </p>
            <p>
                <button id="boton" class="btn btn-primary">Enviar</button>
            </p>
            <p>
                <div id="salida"></div>
            </p>
        </div>
    </div>

    <style type="text/css">
        textarea {
            vertical-align: bottom;
        }

        #salida {
            overflow: auto;
        }

        #salida > p {
            overflow-wrap: break-word;
        }

        #salida span {
            color: blue;
        }

        #salida span.error {
            color: red;
        }
    </style>

    <script type="text/javascript">
        $(document).ready(function () {
            const wsUri = "ws://127.0.0.1:8080/";
            const websocket = new WebSocket(wsUri);

            $(document).on("click", "#boton", onClickButton);

            websocket.onopen = (e) => {
                writeToScreen("CONNECTED");
                doSend("WebSocket rocks");
            };

            websocket.onclose = (e) => {
                writeToScreen("DISCONNECTED");
            };

            websocket.onmessage = (e) => {
                writeToScreen(`<span>RESPONSE: ${e.data}</span>`);
            };

            websocket.onerror = (e) => {
                writeToScreen(`ERROR: ${e.data}`);
            };

            function doSend(message) {
                writeToScreen(`SENT: ${message}`);
                websocket.send(message);
            }

            function writeToScreen(message) {
                $("#salida").append("<p>" + message + "</p>");
            }

            function onClickButton() {
                var text = $("#cajadetexto").val();

                text && doSend(text);
                $("#cajadetexto").val("");
                $("#cajadetexto").focus();
            }
        });
    </script>
</body>
</html>

I based my code on this link: https://github.com/mdn/content/blob/main/files/en-us/web/api/websockets_api/writing_websocket_server/index.md?plain=1

Thanks and I wait your answers.

What I have tried:

I tried implement a server that use multi clients without limited size, also I searched many sites about multi-client but I usually found examples of multi clients using web sockets in console application or in .net core when this code need to be developed with .net framework.

I failed in all my tries.

Posted 21-Dec-22 17:32pm

detectivejd

Updated 2-Jan-23 1:15am

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Comments

adriancs 22-Dec-22 1:20am

I have a portable ASP.NET web server called "CassiniDev", that performs this. It handled request and serves the page. If you're interested, u can go to it's github for the source code. here's the link to the github: https://github.com/adriancs2/CassiniDev

detectivejd 22-Dec-22 9:47am

I saw your solution but I need to implement the web socket with web page as client part and multi client in a server, I don´t know how use threads to this situation with my current code.

2 solutions

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OriginalGriff · Accepted Answer · 2022-12-21T22:18:00

Solution 1

A Socket is a point-to-point connection: one server, one client.
To support one server, multiple clients, you need multiple Sockets: one per client.
The easiest way is to setup each client as a separate thread which creates a socket and stes it to listen. When a client connects to it, you create a new thread with a new Socket for the next one, and so on. WHen the Socket disconnects, the thread is terminated as well.

Posted 21-Dec-22 22:18pm

OriginalGriff

Comments

detectivejd 22-Dec-22 8:30am

Very well, how can i implement thread to multiple client connection?

Because I added a tcpclient list but i don´t know how implement it

string ip = "127.0.0.1";
int port = 8080;
var server = new TcpListener(IPAddress.Parse(ip), port);

server.Start();
Console.WriteLine("Server has started on {0}:{1}, Waiting for a connection…", ip, port);

TcpClient client = server.AcceptTcpClient();
tcpClients.Add(client);
.....

detectivejd · Accepted Answer · 2023-01-02T01:15:00

I resolved the trouble, All that I needed it was encode the messages to that the server had hability of notify other client messages, also I had to create a client list to get all connected clients and detect the real time notifications from the frontend.
The frontend ended to relegated except in the backend (server) interaction.

I pass the code finished.

Server

C#

using System;
using System.Collections.Generic;
using System.Net;
using System.Net.Sockets;
using System.Text;
using System.Text.RegularExpressions;
using System.Threading;
using System.Linq;

namespace Consola
{
    public class Program
    {
        private static List<Socket> clients = new List<Socket>();
        private static TcpListener tcpListener = new TcpListener(
            IPAddress.Parse("127.0.0.1"), 
            8080
        );
        public static void Main(string[] args)
        {
            tcpListener.Start();
            while(true)
            {
                Socket client = tcpListener.AcceptSocket();
                if (client.Connected)
                {
                    clients.Add(client);
                    Thread nuevoHilo = new Thread(() => Listeners(client));
                    nuevoHilo.Start();
                }                    
            }
        }

        private static void Listeners(Socket client)
        {
            Console.WriteLine("Client:" + client.RemoteEndPoint + " now connected to server.");
            NetworkStream stream = new NetworkStream(client);

            while (true)
            {
                while (!stream.DataAvailable) ;
                while (client.Available < 3) ; // match against "get"

                byte[] bytes = new byte[client.Available];
                stream.Read(bytes, 0, bytes.Length);
                string s = Encoding.UTF8.GetString(bytes);

                if (Regex.IsMatch(s, "^GET", RegexOptions.IgnoreCase))
                {
                    Console.WriteLine("=====Handshaking from client=====\n{0}", s);

                    // 1. Obtain the value of the "Sec-WebSocket-Key" request header without any leading or trailing whitespace
                    // 2. Concatenate it with "258EAFA5-E914-47DA-95CA-C5AB0DC85B11" (a special GUID specified by RFC 6455)
                    // 3. Compute SHA-1 and Base64 hash of the new value
                    // 4. Write the hash back as the value of "Sec-WebSocket-Accept" response header in an HTTP response
                    string swk = Regex.Match(s, "Sec-WebSocket-Key: (.*)").Groups[1].Value.Trim();
                    string swka = swk + "258EAFA5-E914-47DA-95CA-C5AB0DC85B11";
                    byte[] swkaSha1 = System.Security.Cryptography.SHA1.Create().ComputeHash(Encoding.UTF8.GetBytes(swka));
                    string swkaSha1Base64 = Convert.ToBase64String(swkaSha1);

                    // HTTP/1.1 defines the sequence CR LF as the end-of-line marker
                    byte[] response = Encoding.UTF8.GetBytes(
                        "HTTP/1.1 101 Switching Protocols\r\n" +
                        "Connection: Upgrade\r\n" +
                        "Upgrade: websocket\r\n" +
                        "Sec-WebSocket-Accept: " + swkaSha1Base64 + "\r\n\r\n");

                    stream.Write(response, 0, response.Length);
                }
                else
                {
                    var text = DecodeMessage(bytes);

                    Console.WriteLine("{0}", text);
                        
                    var otherClients = clients.Where(
                            c => c.RemoteEndPoint != client.RemoteEndPoint
                        ).ToList();

                    if (otherClients.Count > 0)
                    {
                        foreach (var cli in otherClients)
                        {
                            var sendMessage = EncodeMessageToSend(text);
                            cli.Send(sendMessage);
                        }
                    }

                    Console.WriteLine();
                }
            }
        }

        private static string DecodeMessage(byte[] bytes)
        {
            var secondByte = bytes[1];
            var dataLength = secondByte & 127;
            var indexFirstMask = 2;
            if (dataLength == 126)
                indexFirstMask = 4;
            else if (dataLength == 127)
                indexFirstMask = 10;

            var keys = bytes.Skip(indexFirstMask).Take(4);
            var indexFirstDataByte = indexFirstMask + 4;

            var decoded = new byte[bytes.Length - indexFirstDataByte];
            for (int i = indexFirstDataByte, j = 0; i < bytes.Length; i++, j++)
            {
                decoded[j] = (byte)(bytes[i] ^ keys.ElementAt(j % 4));
            }

            return Encoding.UTF8.GetString(decoded, 0, decoded.Length);
        }

        private static byte[] EncodeMessageToSend(string message)
        {
            byte[] response;
            byte[] bytesRaw = Encoding.UTF8.GetBytes(message);
            byte[] frame = new byte[10];

            var indexStartRawData = -1;
            var length = bytesRaw.Length;

            frame[0] = (byte)129;
            if (length <= 125)
            {
                frame[1] = (byte)length;
                indexStartRawData = 2;
            }
            else if (length >= 126 && length <= 65535)
            {
                frame[1] = (byte)126;
                frame[2] = (byte)((length >> 8) & 255);
                frame[3] = (byte)(length & 255);
                indexStartRawData = 4;
            }
            else
            {
                frame[1] = (byte)127;
                frame[2] = (byte)((length >> 56) & 255);
                frame[3] = (byte)((length >> 48) & 255);
                frame[4] = (byte)((length >> 40) & 255);
                frame[5] = (byte)((length >> 32) & 255);
                frame[6] = (byte)((length >> 24) & 255);
                frame[7] = (byte)((length >> 16) & 255);
                frame[8] = (byte)((length >> 8) & 255);
                frame[9] = (byte)(length & 255);

                indexStartRawData = 10;
            }

            response = new byte[indexStartRawData + length];

            int i, reponseIdx = 0;

            //Add the frame bytes to the reponse
            for (i = 0; i < indexStartRawData; i++)
            {
                response[reponseIdx] = frame[i];
                reponseIdx++;
            }

            //Add the data bytes to the response
            for (i = 0; i < length; i++)
            {
                response[reponseIdx] = bytesRaw[i];
                reponseIdx++;
            }

            return response;
        }
    }
}