Discover enumerates and evaluates all known network interfaces and addresses and filters it down to the ones that reach both a LAN and the internet We are only interested in IPv4 addresses because for the most part, domestic ISPs do not issue their customers with IPv6 routing, it's still a pain in the ass outside of large data centre connections.

GetAddressesAndInterfaces returns all of the addresses and interfaces that would be resolved from an automatic addresses that can connect two processes at all.

GetInterface returns the address and interface of multicast-and-internet capable interfaces.

Address is the network address that routes to the gateway and thus the internet.

Gateway stores the current network default gateway as discovered by github.com/jackpal/gateway.

Interface is the net.Interface of the Address above.

IPNet is the subnet of the Gateway's LAN.

SecondaryAddresses are all the other addresses that can be reached from somewhere (including localhost) but not necessarily the internet.

SecondaryInterfaces is the interfaces of the SecondaryAddresses stored in the corresponding slice index.