@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);
    }
}
 

@Override
protected Future<?> execute() {
    List<Socks5AuthMethod> authMethods = new ArrayList<>(2);
    authMethods.add(Socks5AuthMethod.NO_AUTH);
    if ((username != null) || (password != null)) {
        authMethods.add(Socks5AuthMethod.PASSWORD);
    }
    DefaultSocks5InitialRequest initialRequest = new DefaultSocks5InitialRequest(authMethods);

    addFirstOrReplaceHandler(SOCKS_ENCODER_NAME, Socks5ClientEncoder.DEFAULT);
    addFirstOrReplaceHandler(SOCKS_DECODER_NAME, new Socks5InitialResponseDecoder());
    return writeToChannel(initialRequest);
}