Moves to official vendoring solution

vendor/github.com/d2g/dhcp4/helpers.go

@@ -0,0 +1,58 @@
+package dhcp4
+
+import (
+	"encoding/binary"
+	"net"
+	"time"
+)
+
+// IPRange returns how many ips in the ip range from start to stop (inclusive)
+func IPRange(start, stop net.IP) int {
+	//return int(Uint([]byte(stop))-Uint([]byte(start))) + 1
+	return int(binary.BigEndian.Uint32(stop.To4())) - int(binary.BigEndian.Uint32(start.To4())) + 1
+}
+
+// IPAdd returns a copy of start + add.
+// IPAdd(net.IP{192,168,1,1},30) returns net.IP{192.168.1.31}
+func IPAdd(start net.IP, add int) net.IP { // IPv4 only
+	start = start.To4()
+	//v := Uvarint([]byte(start))
+	result := make(net.IP, 4)
+	binary.BigEndian.PutUint32(result, binary.BigEndian.Uint32(start)+uint32(add))
+	//PutUint([]byte(result), v+uint64(add))
+	return result
+}
+
+// IPLess returns where IP a is less than IP b.
+func IPLess(a, b net.IP) bool {
+	b = b.To4()
+	for i, ai := range a.To4() {
+		if ai != b[i] {
+			return ai < b[i]
+		}
+	}
+	return false
+}
+
+// IPInRange returns true if ip is between (inclusive) start and stop.
+func IPInRange(start, stop, ip net.IP) bool {
+	return !(IPLess(ip, start) || IPLess(stop, ip))
+}
+
+// OptionsLeaseTime - converts a time.Duration to a 4 byte slice, compatible
+// with OptionIPAddressLeaseTime.
+func OptionsLeaseTime(d time.Duration) []byte {
+	leaseBytes := make([]byte, 4)
+	binary.BigEndian.PutUint32(leaseBytes, uint32(d/time.Second))
+	//PutUvarint(leaseBytes, uint64(d/time.Second))
+	return leaseBytes
+}
+
+// JoinIPs returns a byte slice of IP addresses, one immediately after the other
+// This may be useful for creating multiple IP options such as OptionRouter.
+func JoinIPs(ips []net.IP) (b []byte) {
+	for _, v := range ips {
+		b = append(b, v.To4()...)
+	}
+	return
+}