Socks5PasswordAuthRequestDecoder Class — netty Architecture

Source Code

codec-socks/src/main/java/io/netty/handler/codec/socksx/v5/Socks5PasswordAuthRequestDecoder.java lines 36–99

public class Socks5PasswordAuthRequestDecoder extends ReplayingDecoder<State> {

    @UnstableApi
    public enum State {
        INIT,
        SUCCESS,
        FAILURE
    }

    public Socks5PasswordAuthRequestDecoder() {
        super(State.INIT);
    }

    @Override
    protected void decode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) throws Exception {
        try {
            switch (state()) {
            case INIT: {
                final int startOffset = in.readerIndex();
                final byte version = in.getByte(startOffset);
                if (version != 1) {
                    throw new DecoderException("unsupported subnegotiation version: " + version + " (expected: 1)");
                }

                final int usernameLength = in.getUnsignedByte(startOffset + 1);
                final int passwordLength = in.getUnsignedByte(startOffset + 2 + usernameLength);
                final int totalLength = usernameLength + passwordLength + 3;

                in.skipBytes(totalLength);
                out.add(new DefaultSocks5PasswordAuthRequest(
                        in.toString(startOffset + 2, usernameLength, CharsetUtil.US_ASCII),
                        in.toString(startOffset + 3 + usernameLength, passwordLength, CharsetUtil.US_ASCII)));

                checkpoint(State.SUCCESS);
            }
            case SUCCESS: {
                int readableBytes = actualReadableBytes();
                if (readableBytes > 0) {
                    out.add(in.readRetainedSlice(readableBytes));
                }
                break;
            }
            case FAILURE: {
                in.skipBytes(actualReadableBytes());
                break;
            }
            }
        } catch (Exception e) {
            fail(out, e);
        }
    }

    private void fail(List<Object> out, Exception cause) {
        if (!(cause instanceof DecoderException)) {
            cause = new DecoderException(cause);
        }

        checkpoint(State.FAILURE);

        Socks5Message m = new DefaultSocks5PasswordAuthRequest("", "");
        m.setDecoderResult(DecoderResult.failure(cause));
        out.add(m);
    }
}