See the complaint on #4039. This doesn't fix that particular
issue (it's somewhat unrelated), but does solve around
a file parsing problem reported by @void-in
This does change some of the meaning of the required-ness of the
directories. Before, if you wanted to serve files, but not receive any,
you would just fail to set a OUTPUTPATH.
Now, since both are required, users are required to both send and
recieve. This seems okay, you can always just set two different
locations and point the one you don't want at /dev/null or something.
Otherwise you will tend to listen on your default ipv6 'any' address and
bound to udp6 port 69, assuming you haven't bothered to disable your
automatically-enabled ipv6 stack.
This is almost never correct.