My solutions to a set of server programming challenges published here: https://protohackers.com/
The grader here seems to be very lax, according to the problem description we might get an input like 1.3e1 to which we'd obviously have to return true, but such an input never occurs.
Sum is biiig
Be careful to not inform a user about events that happened after the user connected but before they fully joined.
Don't strip newlines!
Don't get confused by reading the messages sent by the tester. One message reads "7PBqhi52gBQukUuL4EUegLYQHW is too short", yet the address is valid and should be replaced.
Let me know if anyone finds a nice identity test for the cipher spec. I just ended up brute-forcing it.
Serving 1000 clients at a time, on Linux, requires an increased open file limit. ulimit -n shows the current limit, ulimit -n 10000 increases the limit. This increased limit is only valid within and for the duration of the current shell.
Resource temporarily unavailable (os error 11) can be caused by TcpStream::set_read_timeout.
Make sure to catch not just too small lengths, but also too long.