MinecraftPing.java

/*
 * Copyright 2014 jamietech. All rights reserved.
 * https://github.com/jamietech/MinecraftServerPing
 *
 * Redistribution and use in source and binary forms, with or without modification, are
 * permitted provided that the following conditions are met:
 *
 *    1. Redistributions of source code must retain the above copyright notice, this list of
 *       conditions and the following disclaimer.
 *
 *    2. Redistributions in binary form must reproduce the above copyright notice, this list
 *       of conditions and the following disclaimer in the documentation and/or other materials
 *       provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ''AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
 * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * The views and conclusions contained in the software and documentation are those of the
 * authors and contributors and should not be interpreted as representing official policies,
 * either expressed or implied, of anybody else.
 */

package co.foxdev.foxbot.utils.minecraft;

import com.google.gson.Gson;

import java.io.ByteArrayOutputStream;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.net.InetSocketAddress;
import java.net.Socket;

public class MinecraftPing
{

    /**
     * Fetches a {@link MinecraftPingReply} for the supplied hostname.
     * <b>Assumed timeout of 2s and port of 25565.</b>
     *
     * @param hostname - a valid String hostname
     * @return {@link MinecraftPingReply}
     * @throws IOException
     */
    public MinecraftPingReply getPing(final String hostname) throws IOException
    {
        return this.getPing(new MinecraftPingOptions().setHostname(hostname));
    }

    /**
     * Fetches a {@link MinecraftPingReply} for the supplied options.
     *
     * @param options - a filled instance of {@link MinecraftPingOptions}
     * @return {@link MinecraftPingReply}
     * @throws IOException
     */
    public MinecraftPingReply getPing(final MinecraftPingOptions options) throws IOException
    {
        MinecraftPingUtil.validate(options.getHostname(), "Hostname cannot be null.");
        MinecraftPingUtil.validate(options.getPort(), "Port cannot be null.");
        final Socket socket = new Socket();
        socket.connect(new InetSocketAddress(options.getHostname(), options.getPort()), options.getTimeout());
        final DataInputStream in = new DataInputStream(socket.getInputStream());
        final DataOutputStream out = new DataOutputStream(socket.getOutputStream());
        //> Handshake
        ByteArrayOutputStream handshake_bytes = new ByteArrayOutputStream();
        DataOutputStream handshake = new DataOutputStream(handshake_bytes);
        handshake.writeByte(MinecraftPingUtil.PACKET_HANDSHAKE);
        MinecraftPingUtil.writeVarInt(handshake, MinecraftPingUtil.PROTOCOL_VERSION);
        MinecraftPingUtil.writeVarInt(handshake, options.getHostname().length());
        handshake.writeBytes(options.getHostname());
        handshake.writeShort(options.getPort());
        MinecraftPingUtil.writeVarInt(handshake, MinecraftPingUtil.STATUS_HANDSHAKE);
        MinecraftPingUtil.writeVarInt(out, handshake_bytes.size());
        out.write(handshake_bytes.toByteArray());
        //> Status request
        out.writeByte(0x01); // Size of packet
        out.writeByte(MinecraftPingUtil.PACKET_STATUSREQUEST);
        //< Status response
        MinecraftPingUtil.readVarInt(in); // Size
        int id = MinecraftPingUtil.readVarInt(in);
        MinecraftPingUtil.io(id == -1, "Server prematurely ended stream.");
        MinecraftPingUtil.io(id != MinecraftPingUtil.PACKET_STATUSREQUEST, "Server returned invalid packet.");
        int length = MinecraftPingUtil.readVarInt(in);
        MinecraftPingUtil.io(length == -1, "Server prematurely ended stream.");
        MinecraftPingUtil.io(length == 0, "Server returned unexpected value.");
        byte[] data = new byte[length];
        in.readFully(data);
        String json = new String(data, options.getCharset());
        //> Ping
        out.writeByte(0x09); // Size of packet
        out.writeByte(MinecraftPingUtil.PACKET_PING);
        out.writeLong(System.currentTimeMillis());
        //< Ping
        MinecraftPingUtil.readVarInt(in); // Size
        id = MinecraftPingUtil.readVarInt(in);
        MinecraftPingUtil.io(id == -1, "Server prematurely ended stream.");
        MinecraftPingUtil.io(id != MinecraftPingUtil.PACKET_PING, "Server returned invalid packet.");
        // Close
        handshake.close();
        handshake_bytes.close();
        out.close();
        in.close();
        socket.close();
        return new Gson().fromJson(json, MinecraftPingReply.class);
    }
}