philesd.java

package com.t99sdevelopment.philesd;

import javax.xml.bind.DatatypeConverter;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.ServerSocket;
import java.net.Socket;
import java.security.MessageDigest;
import java.util.Scanner;
import java.util.regex.*;

public class Main {

    public static void main (String[] args) {

        ServerSocket server;
        Socket client;
        InputStream in;
        OutputStream out;

        try {

            server = new ServerSocket(1234);

            System.out.println("Server has started on localhost.\r\nWaiting for a connection...");

            client = server.accept();

            System.out.println("A client connected.");

            in = client.getInputStream();
            out = client.getOutputStream();

            String data = new Scanner(in, "UTF-8").useDelimiter("\\r\\n\\r\\n").next();

            Matcher get = Pattern.compile("^GET").matcher(data);

            if (get.find()) { // Do not ask me to explain this, just see https://developer.mozilla.org/en-US/docs/Web/API/WebSockets_API/Writing_a_WebSocket_server_in_Java#Handshaking

                Matcher match = Pattern.compile("Sec-WebSocket-Key: (.*)").matcher(data);
                match.find();
                byte[] response = ("HTTP/1.1 101 Switching Protocols\r\n" + "Connection: Upgrade\r\n" + "Upgrade: websocket\r\n" + "Sec-WebSocket-Accept: " + DatatypeConverter.printBase64Binary(MessageDigest.getInstance("SHA-1").digest((match.group(1) + "258EAFA5-E914-47DA-95CA-C5AB0DC85B11").getBytes("UTF-8"))) + "\r\n\r\n").getBytes("UTF-8");
                out.write(response, 0, response.length);

            } else {

                //

            }

            byte[] testMessage = ("Testing... testing... 1 2 3.").getBytes("UTF-8");
            out.write(testMessage, 0, testMessage.length);

        } catch (Exception e) {

            System.out.println(e);

        }

    }

}