Feature request: bandwidth accounting

It would be extremely helpful if muonproxy stored counters for the amount of data (bytes) transfered from and to every client IP, and provided a way to request this data from the server at runtime. Some ways to implement this that I can think of are: a) signal handler - output the counters into a specified file or file descriptor upon receiving a specific signal (like SIGUSR1) b) dedicated "admin" UNIX or UDP socket that accepts commands and returns data