unwrap

Parse a datagram received on relay off the relay, stripping the SOCKS5 reply header (RSV[2] FRAG ATYP ADDR PORT). Returns the origin (host, port) and the inner payload, or null if the datagram is too short, fragmented (FRAG != 0), or otherwise malformed: the same packets libtorrent's socks5_unwrap returns false for and the caller drops.