add vendor

vendor/github.com/apparentlymart/go-cidr/cidr/wrangling.go

@@ -0,0 +1,37 @@
+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)
+}