Can't read any data when protocol set to origin

[CuberL]

I just working on a SSR speed test project base on your library. But I found that when I set protocol to origin, I can't read any data from server side. After checking your code, I found a line may cause that problem

shadowsocksR/tcp.go

Lines 180 to 186 in b0d026c

	postDecryptedData, length, err := c.IProtocol.PostDecrypt(encryptbuf)
	if err != nil {
	return 0, err
	}
	if length == 0 {
	c.readEncryptBuf.Write(encryptbuf)
	return 0, nil

It return nothing when PostDecrypt return length = 0. I removed line 186 in local and it works. Can check if it is a bug. Thx for your awesome library. 👍