Test whether an IP address falls within a CIDR block. A well-formed address of a different family (or simply outside the block) returns contains=false — not an error.

Return both the fully-expanded (eight 4-hex groups) and canonical compressed (RFC 5952) forms of an address. IPv4 is returned unchanged in both fields.

Parse an IPv4 or IPv6 address and classify it — version, normalized form and RFC range (unicast, private, loopback, linkLocal, multicast, uniqueLocal, ipv4Mapped, …). Detects IPv4-mapped IPv6.

Compute network details of a CIDR block — network & broadcast address, usable host range, total and usable address counts. Works for IPv4 and IPv6 (counts returned as strings for large IPv6 blocks). Honours RFC 3021 for /31.