http://i3xi5qxvbrngh3g6o7czwjfxwjzigook7zxzjmgwg5b7xnjcn5hzciad.onion/control-spec/index.html
Implementors are
recommended to avoid using TC directly, but instead to use a library that
can easily be updated to use the newer protocol. (Version 0 is used by Tor
versions 0.1.0.x; the protocol in this document only works with Tor
versions in the 0.1.1.x series and later.)