GetRandomPort returns a random port chosen by the OS by binding to :0 and checking what port was bound.

InAddrAnyFor returns the special IP address to bind to any IP address (0.0.0.0 or ::) depending on IP family.

IPLiteralFor returns the given IP as a literal that can be used in a resource identifier.

IPToRFCForm normalizes the IP address given to fit the expected network byte order octet form described in https://tools.ietf.org/html/rfc5280#section-4.2.1.6.

LoopbackFor returns the loopback address for the given IP family.

LoopbackHostPort formats a loopback address and port correctly for the given IP family.

ToIPFamily tries to detect the IP family (IPv4 or IPv6) based on the given IP string.

Dialer is something that can be used to create network connections.