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package rings
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import "net/netip"
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// AddrFromU32 converts a 32bit value into an IPv4
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// address.
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func AddrFromU32(v uint32) netip.Addr {
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return AddrFrom4(
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uint(v>>24),
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uint(v>>16),
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uint(v>>8),
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uint(v),
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)
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}
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// AddrFrom4 assembles an IPv4 address for 4 numbers.
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// each number is truncated to 8-bits.
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func AddrFrom4(a, b, c, d uint) netip.Addr {
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return netip.AddrFrom4([4]byte{
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byte(a & 0xff),
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byte(b & 0xff),
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byte(c & 0xff),
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byte(d & 0xff),
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})
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}
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// AddrToU32 converts a valid IPv4 address into it's
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// 32bit numeric representation.
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func AddrToU32(addr netip.Addr) (v uint32, ok bool) {
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if addr.IsValid() {
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if addr.Is4() || addr.Is4In6() {
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a4 := addr.As4()
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v = uint32(a4[0])<<24 +
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uint32(a4[1])<<16 +
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uint32(a4[2])<<8 +
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uint32(a4[3])
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return v, true
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}
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}
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return 0, false
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}
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// PrefixToRange returns the beginning and end of a
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// [netip.Prefix] (aka CIDR or subnet).
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func PrefixToRange(subnet netip.Prefix) (from, to netip.Addr, ok bool) {
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var u uint32
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addr := subnet.Addr()
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if u, ok = AddrToU32(addr); ok {
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bits := subnet.Bits()
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switch {
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case bits > 32, bits < 0:
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// bad
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case bits == 32:
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// single
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from, to, ok = addr, addr, true
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default:
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// subnet
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shift := 32 - bits
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m1 := uint32((1 << shift) - 1)
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m0 := uint32(0xffffffff) & ^m1
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u0 := u & m0
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u1 := u0 + m1
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ok = true
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from = AddrFromU32(u0)
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to = AddrFromU32(u1)
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}
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}
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return from, to, ok
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}
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