GameSession.java

package emu.grasscutter.server.game;

import java.io.File;
import java.net.InetSocketAddress;
import java.util.Set;
import emu.grasscutter.Grasscutter;
import emu.grasscutter.Grasscutter.ServerDebugMode;
import emu.grasscutter.game.Account;
import emu.grasscutter.game.player.Player;
import emu.grasscutter.net.packet.BasePacket;
import emu.grasscutter.net.packet.PacketOpcodes;
import emu.grasscutter.net.packet.PacketOpcodesUtil;
import emu.grasscutter.server.event.game.SendPacketEvent;
import emu.grasscutter.utils.Crypto;
import emu.grasscutter.utils.FileUtils;
import emu.grasscutter.utils.Utils;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;

import static emu.grasscutter.config.Configuration.*;
import static emu.grasscutter.utils.Language.translate;

public class GameSession implements GameSessionManager.KcpChannel {
	private final GameServer server;
	private GameSessionManager.KcpTunnel tunnel;

	private Account account;
	private Player player;

	private boolean useSecretKey;
	private SessionState state;

	private int clientTime;
	private long lastPingTime;
	private int lastClientSeq = 10;

	public GameSession(GameServer server) {
		this.server = server;
		this.state = SessionState.WAITING_FOR_TOKEN;
		this.lastPingTime = System.currentTimeMillis();
	}

	public GameServer getServer() {
		return server;
	}

	public InetSocketAddress getAddress() {
		try{
			return tunnel.getAddress();
		}catch (Throwable ignore){
			return null;
		}
	}

	public boolean useSecretKey() {
		return useSecretKey;
	}

	public Account getAccount() {
		return account;
	}

	public void setAccount(Account account) {
		this.account = account;
	}

	public String getAccountId() {
		return this.getAccount().getId();
	}

	public Player getPlayer() {
		return player;
	}

	public synchronized void setPlayer(Player player) {
		this.player = player;
		this.player.setSession(this);
		this.player.setAccount(this.getAccount());
	}

	public SessionState getState() {
		return state;
	}

	public void setState(SessionState state) {
		this.state = state;
	}

	public boolean isLoggedIn() {
		return this.getPlayer() != null;
	}

	public void setUseSecretKey(boolean useSecretKey) {
		this.useSecretKey = useSecretKey;
	}

	public int getClientTime() {
		return this.clientTime;
	}

	public long getLastPingTime() {
		return lastPingTime;
	}

	public void updateLastPingTime(int clientTime) {
		this.clientTime = clientTime;
		this.lastPingTime = System.currentTimeMillis();
	}

	public int getNextClientSequence() {
		return ++lastClientSeq;
	}

    public void replayPacket(int opcode, String name) {
    	String filePath = PACKET(name);
		File p = new File(filePath);

		if (!p.exists()) return;

		byte[] packet = FileUtils.read(p);

		BasePacket basePacket = new BasePacket(opcode);
		basePacket.setData(packet);

		send(basePacket);
    }

    public void logPacket( String sendOrRecv, int opcode, byte[] payload) {
        Grasscutter.getLogger().info(sendOrRecv + ": " + PacketOpcodesUtil.getOpcodeName(opcode) + " (" + opcode + ")");
        System.out.println(Utils.bytesToHex(payload));
    }
    public void send(BasePacket packet) {
    	// Test
    	if (packet.getOpcode() <= 0) {
    		Grasscutter.getLogger().warn("Tried to send packet with missing cmd id!");
    		return;
    	}

		// DO NOT REMOVE (unless we find a way to validate code before sending to client which I don't think we can)
		// Stop WindSeedClientNotify from being sent for security purposes.
		if(PacketOpcodes.BANNED_PACKETS.contains(packet.getOpcode())) {
			return;
		}

    	// Header
    	if (packet.shouldBuildHeader()) {
    		packet.buildHeader(this.getNextClientSequence());
    	}

    	// Log
    	switch (GAME_INFO.logPackets) {
    	    case ALL -> {
    	        if (!loopPacket.contains(packet.getOpcode())) {
                    logPacket("SEND", packet.getOpcode(), packet.getData());
                }
    	    }
    	    case WHITELIST-> {
    	        if (SERVER.debugWhitelist.contains(packet.getOpcode())) {
    	            logPacket("SEND", packet.getOpcode(), packet.getData());
    	        }
    	    }
    	    case BLACKLIST-> {
                if (!SERVER.debugBlacklist.contains(packet.getOpcode())) {
                    logPacket("SEND", packet.getOpcode(), packet.getData());
                }
            }
    	    default -> {}
    	}

		// Invoke event.
		SendPacketEvent event = new SendPacketEvent(this, packet); event.call();
    	if(!event.isCanceled()) { // If event is not cancelled, continue.
			tunnel.writeData(event.getPacket().build());
		}
    }

	private static final Set<Integer> loopPacket = Set.of(
			PacketOpcodes.PingReq,
			PacketOpcodes.PingRsp,
			PacketOpcodes.WorldPlayerRTTNotify,
			PacketOpcodes.UnionCmdNotify,
			PacketOpcodes.QueryPathReq
	);

	@Override
	public void onConnected(GameSessionManager.KcpTunnel tunnel) {
		this.tunnel = tunnel;
		Grasscutter.getLogger().info(translate("messages.game.connect", this.getAddress().toString()));
	}


	@Override
	public void handleReceive(byte[] bytes) {
		// Decrypt and turn back into a packet
		Crypto.xor(bytes, useSecretKey() ? Crypto.ENCRYPT_KEY : Crypto.DISPATCH_KEY);
		ByteBuf packet = Unpooled.wrappedBuffer(bytes);

		// Log
		//logPacket(packet);
		// Handle
		try {
			boolean allDebug = GAME_INFO.logPackets == ServerDebugMode.ALL;
			while (packet.readableBytes() > 0) {
				// Length
				if (packet.readableBytes() < 12) {
					return;
				}
				// Packet sanity check
				int const1 = packet.readShort();
				if (const1 != 17767) {
					if(allDebug){
						Grasscutter.getLogger().error("Bad Data Package Received: got {} ,expect 17767",const1);
					}
					return; // Bad packet
				}
				// Data
				int opcode = packet.readShort();
				int headerLength = packet.readShort();
				int payloadLength = packet.readInt();
				byte[] header = new byte[headerLength];
				byte[] payload = new byte[payloadLength];

				packet.readBytes(header);
				packet.readBytes(payload);
				// Sanity check #2
				int const2 = packet.readShort();
				if (const2 != -30293) {
					if(allDebug){
						Grasscutter.getLogger().error("Bad Data Package Received: got {} ,expect -30293",const2);
					}
					return; // Bad packet
				}
				
				// Log packet
				switch (GAME_INFO.logPackets) {
    	            case ALL -> {
    	                if (!loopPacket.contains(opcode)) {
                            logPacket("RECV",opcode, payload);
                        }
    	            }
    	            case WHITELIST-> {
    	                if (SERVER.debugWhitelist.contains(opcode)) {
    	                    logPacket("RECV",opcode, payload);
    	                }
    	            }
    	            case BLACKLIST-> {
    	                if (!(SERVER.debugBlacklist.contains(opcode))) {
    	                    logPacket("RECV",opcode, payload);
    	                }
    	            }
    	            default -> {}
    	        }

				// Handle
				getServer().getPacketHandler().handle(this, opcode, header, payload);
			}
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			//byteBuf.release(); //Needn't
			packet.release();
		}
	}

	@Override
	public void handleClose() {
		setState(SessionState.INACTIVE);
		//send disconnection pack in case of reconnection
		Grasscutter.getLogger().info(translate("messages.game.disconnect", this.getAddress().toString()));
		// Save after disconnecting
		if (this.isLoggedIn()) {
			Player player = getPlayer();
			// Call logout event.
			player.onLogout();
		}
		try {
			send(new BasePacket(PacketOpcodes.ServerDisconnectClientNotify));
		}catch (Throwable ignore){
			Grasscutter.getLogger().warn("closing {} error",getAddress().getAddress().getHostAddress());
		}
		tunnel = null;
	}

	public void close() {
		tunnel.close();
	}

	public boolean isActive() {
		return getState() == SessionState.ACTIVE;
	}

	public enum SessionState {
		INACTIVE,
		WAITING_FOR_TOKEN,
		WAITING_FOR_LOGIN,
		PICKING_CHARACTER,
		ACTIVE
	}
}