@Override
protected boolean handleProxyProtocol(ChannelHandlerContext ctx, Object msg) throws Exception {
    if (!authenticated) {
        authenticated = authenticate(ctx, msg);
        return false;
    }

    Socks5CommandRequest req = (Socks5CommandRequest) msg;
    assertThat(req.type(), is(Socks5CommandType.CONNECT));

    Socks5CommandResponse res =
            new DefaultSocks5CommandResponse(Socks5CommandStatus.SUCCESS, Socks5AddressType.IPv4);
    intermediaryDestination = SocketUtils.socketAddress(req.dstAddr(), req.dstPort());

    ctx.write(res);

    ctx.pipeline().remove(ENCODER);
    ctx.pipeline().remove(DECODER);

    return true;
}
 

private void onSocksSuccess(ChannelHandlerContext ctx, Socks5CommandRequest request) {
    Address serverAddr = new Address(request.dstAddr(), request.dstPort());
    createServerChannel(ctx, serverAddr).addListener(new ChannelFutureListener() {
        @Override
        public void operationComplete(ChannelFuture future) throws Exception {
            if (future.isSuccess()) {
                ConnectionInfo newConnectionInfo = new ConnectionInfo(
                        connectionInfo.getClientAddr(), serverAddr);
                ctx.writeAndFlush(new DefaultSocks5CommandResponse(
                        Socks5CommandStatus.SUCCESS,
                        request.dstAddrType(),
                        request.dstAddr(),
                        request.dstPort()));

                onServerConnected(ctx, newConnectionInfo, future.channel());
            } else {
                ctx.channel().writeAndFlush(new DefaultSocks5CommandResponse(
                        Socks5CommandStatus.FAILURE,
                        request.dstAddrType(),
                        request.dstAddr(),
                        request.dstPort()));
                ctx.close();
            }
        }
    });
}
 

@Override
protected void channelRead0(ChannelHandlerContext ctx, Socks5Message msg) throws Exception {
    if (msg instanceof DefaultSocks5InitialRequest) {
        ctx.pipeline().addBefore(ctx.name(), Socks5CommandRequestDecoder.class.getName(),
                                 new Socks5CommandRequestDecoder());
        ctx.writeAndFlush(new DefaultSocks5InitialResponse(Socks5AuthMethod.NO_AUTH));
    } else if (msg instanceof DefaultSocks5CommandRequest) {
        final DefaultSocks5CommandRequest req = (DefaultSocks5CommandRequest) msg;
        ctx.pipeline().remove(Socks5CommandRequestDecoder.class);
        ctx.fireUserEventTriggered(new ProxySuccessEvent(
                new InetSocketAddress(req.dstAddr(), req.dstPort()),
                new DefaultSocks5CommandResponse(Socks5CommandStatus.SUCCESS,
                                                 Socks5AddressType.IPv4)));
    } else {
        throw new IllegalStateException("unexpected msg: " + msg);
    }
}