4 Protocol is very simple: two
5 @url{https://en.wikipedia.org/wiki/Netstring, netstring}s are sent over TCP.
6 First one holds desired filename extension, without the leading dot, up to 9
7 characters long. Second one is the paste data itself.
10 "hello world", no explicit extension => 0:,11:hello world,
11 "http://example.com/", "url" extension => 3:url,18:http://example.com,