RFC 8305 describes how to connect to a remote host, given that the host may have multiple addresses (IPv4 and IPv6, via DNS A and AAAA resource records), and the local host may have connectivity via IPv4 only, IPv6 only, or both. The preference is to use IPv6.
This package implements the given RFC in its core (Happy_eyeballs module). In addition, the Happy_eyeballs_lwt is a Lwt implementation using Unix.
The implemented state machine is kept in-sync with the code (source: happy_eyeballs.dot at the root of this repository).
It is licensed under the ISC license.
opam install happy-eyeballs happy-eyeballs-lwt happy-eyeballs-mirage