[yrro]

You're probably aware of c-ares, if not then check it out unless you really want to write your own.

(As an administrator I'm getting a bit tired of working around the differing bugs and behaviour of different resolver implementations).

glibc also has an async getaddrinfo_a function for asynchronous name resolution, with completion notification.

[matheusmoreira]

I will look into it even if I end up writing my own. Reading source code is always helpful. Thank you.