TODO

* Non-blocking connect() to backend server
* Non-blocking DNS resolution
** Allow nameservers to be specified in configuration file
* Allow source address for connection to backend to be specified
* Reimplement configuration reloading
* Optionally dump invalid requests to file
* Per connection access logging including hostname, bytes rx/tx, src/dst ip/port, timestamp and duration
* Improved table backend lookup, currently this is a linear search
** Considering splitting hostname at label boundaries and search backwards from TLD
* HTTP or DNS interface for backend servers to determine remote IP and port of connection