Read/Write on shadowsocks/conn should be thread safe

[dunjut]

GoDoc on net.Conn says Multiple goroutines may invoke methods on a Conn simultaneously.

shadowsocks/conn doesn't follow the thread-safe assumption, this may break some code in future use.

[arthurkiller]

I did not understand what's wrong.

[dunjut]

When multiple goroutines invoke Read/Write simultaneously, there will be race conditions loading/assigning on Cipher, readBuf and writeBuf. There's no any lock mechanism protecting this.

It wouldn't cause any problems so far because shadowsocks seems not using Conn anywhere in concurrent context.

I'm just suggesting that Conn should eventually be thread-safe because that's how a net.Conn interface behaves.