Parse and inspect
ip, err := netip.ParseAddr("192.0.2.1")
fmt.Println(ip.Is4(), ip.Is6())
fmt.Println(ip.IsPrivate(), ip.IsLoopback())
v6 := netip.MustParseAddr("2001:db8::1")
fmt.Println(v6.Is4(), v6.Is6())net/netip
A modern, comparable, immutable IP address type. Zero allocations, usable as a map key. Prefer this over net.IP in new code.
Why netip over net.IP?
net.IP is a []byte — not comparable, allocates, has representation ambiguities (v4 in v6). netip.Addr is a struct: comparable with ==, usable as a map key, fixed size, no allocations.
Addr — a single IP
Use as a map key
seen := map[netip.Addr]int{}
seen[ip]++ // can't do this with net.IPAddrPort — Addr + port number
Parse a host:port
ap, _ := netip.ParseAddrPort("192.0.2.1:443")
fmt.Println(ap.Addr(), ap.Port())Prefix — CIDR-style subnet
Containment checks
p := netip.MustParsePrefix("10.0.0.0/8")
fmt.Println(p.Contains(netip.MustParseAddr("10.1.2.3"))) // true
fmt.Println(p.Contains(netip.MustParseAddr("192.0.2.1"))) // false