Schreiben eines WebSocket-Servers in C#

TcpListener(System.Net.IPAddress localAddr, int port)

using System.Net.Sockets; using System.Net; using System; class Server { public static void Main() { TcpListener server = new TcpListener(IPAddress.Parse("127.0.0.1"), 80); server.Start(); Console.WriteLine("Server has started on 127.0.0.1:80.{0}Waiting for a connection…", Environment.NewLine); TcpClient client = server.AcceptTcpClient(); Console.WriteLine("A client connected."); } }

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); byte[] bytes = new byte[client.Available]; stream.Read(bytes, 0, bytes.Length); }

using System.Text; using System.Text.RegularExpressions; while(client.Available < 3) { // wait for enough bytes to be available } byte[] bytes = new byte[client.Available]; stream.Read(bytes, 0, bytes.Length); // Translate bytes of request to string String data = Encoding.UTF8.GetString(bytes); if (Regex.IsMatch(data, "^GET")) { } else { }

if (new System.Text.RegularExpressions.Regex("^GET").IsMatch(data)) { const string eol = "\r\n"; // 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" + eol + "Connection: Upgrade" + eol + "Upgrade: websocket" + eol + "Sec-WebSocket-Accept: " + Convert.ToBase64String( System.Security.Cryptography.SHA1.Create().ComputeHash( Encoding.UTF8.GetBytes( new System.Text.RegularExpressions.Regex("Sec-WebSocket-Key: (.*)").Match(data).Groups[1].Value.Trim() + "258EAFA5-E914-47DA-95CA-C5AB0DC85B11" ) ) ) + eol + eol); stream.Write(response, 0, response.Length); }

byte[] decoded = new byte[3]; byte[] encoded = new byte[3] {112, 16, 109}; byte[] mask = new byte[4] {61, 84, 35, 6}; for (int i = 0; i < encoded.Length; i++) { decoded[i] = (byte)(encoded[i] ^ mask[i % 4]); }

// // csc ws-server.cs // ws-server.exe using System; using System.Net; using System.Net.Sockets; using System.Text; using System.Text.RegularExpressions; class Server { public static void Main() { string ip = "127.0.0.1"; int port = 80; 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, 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 swkAndSalt = swk + "258EAFA5-E914-47DA-95CA-C5AB0DC85B11"; byte[] swkAndSaltSha1 = System.Security.Cryptography.SHA1.Create().ComputeHash(Encoding.UTF8.GetBytes(swkAndSalt)); string swkAndSaltSha1Base64 = Convert.ToBase64String(swkAndSaltSha1); // 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: " + swkAndSaltSha1Base64 + "\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 ulong offset = 2, msgLen = bytes[1] & (ulong)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[offset + i] ^ masks[i % 4]); string text = Encoding.UTF8.GetString(decoded); Console.WriteLine("{0}", text); } else Console.WriteLine("mask bit not set"); Console.WriteLine(); } } } }

<!doctype html> <html lang="en"> <head> <link rel="stylesheet" href="styles.css" /> <script src="client.js" defer></script> </head> <body> <h2>WebSocket Test</h2> <textarea cols="60" rows="6"></textarea> <button>send</button> <div id="output"></div> </body> </html>

textarea { vertical-align: bottom; } #output { overflow: auto; } #output > p { overflow-wrap: break-word; } #output span { color: blue; } #output span.error { color: red; }

// http://www.websocket.org/echo.html const button = document.querySelector("button"); const output = document.querySelector("#output"); const textarea = document.querySelector("textarea"); const wsUri = "ws://127.0.0.1/"; const websocket = new WebSocket(wsUri); button.addEventListener("click", 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(`<span class="error">ERROR:</span> ${e.data}`); }; function doSend(message) { writeToScreen(`SENT: ${message}`); websocket.send(message); } function writeToScreen(message) { output.insertAdjacentHTML("afterbegin", `<p>${message}</p>`); } function onClickButton() { const text = textarea.value; text && doSend(text); textarea.value = ""; textarea.focus(); }