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package cidr
import (
"fmt"
"math/big"
"net"
)
func ipToInt(ip net.IP) (*big.Int, int) {
val := &big.Int{}
val.SetBytes([]byte(ip))
if len(ip) == net.IPv4len {
return val, 32
} else if len(ip) == net.IPv6len {
return val, 128
} else {
panic(fmt.Errorf("Unsupported address length %d", len(ip)))
}
}
func intToIP(ipInt *big.Int, bits int) net.IP {
ipBytes := ipInt.Bytes()
ret := make([]byte, bits/8)
// Pack our IP bytes into the end of the return array,
// since big.Int.Bytes() removes front zero padding.
for i := 1; i <= len(ipBytes); i++ {
ret[len(ret)-i] = ipBytes[len(ipBytes)-i]
}
return net.IP(ret)
}
func insertNumIntoIP(ip net.IP, bigNum *big.Int, prefixLen int) net.IP {
ipInt, totalBits := ipToInt(ip)
bigNum.Lsh(bigNum, uint(totalBits-prefixLen))
ipInt.Or(ipInt, bigNum)
return intToIP(ipInt, totalBits)
}
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