fix bug on getting NextIP of addresses with first byte 0

1. get the right next IP of addresses of first byte 0
2. refactor some methods to handle illegal IPs or IPNets
3. add some unit tests

Signed-off-by: Bruce Ma <brucema19901024@gmail.com>

pkg/ip/cidr.go

@@ -19,43 +19,87 @@ import (
 	"net"
 )
 
-// NextIP returns IP incremented by 1
+// NextIP returns IP incremented by 1, if IP is invalid, return nil
 func NextIP(ip net.IP) net.IP {
-	i := ipToInt(ip)
+	normalizedIP := normalizeIP(ip)
-	return intToIP(i.Add(i, big.NewInt(1)))
+	if normalizedIP == nil {
+		return nil
+	}
+
+	i := ipToInt(normalizedIP)
+	return intToIP(i.Add(i, big.NewInt(1)), len(normalizedIP) == net.IPv6len)
 }
 
-// PrevIP returns IP decremented by 1
+// PrevIP returns IP decremented by 1, if IP is invalid, return nil
 func PrevIP(ip net.IP) net.IP {
-	i := ipToInt(ip)
+	normalizedIP := normalizeIP(ip)
-	return intToIP(i.Sub(i, big.NewInt(1)))
+	if normalizedIP == nil {
+		return nil
+	}
+
+	i := ipToInt(normalizedIP)
+	return intToIP(i.Sub(i, big.NewInt(1)), len(normalizedIP) == net.IPv6len)
 }
 
 // Cmp compares two IPs, returning the usual ordering:
 // a < b : -1
 // a == b : 0
 // a > b : 1
+// incomparable : -2
 func Cmp(a, b net.IP) int {
-	aa := ipToInt(a)
+	normalizedA := normalizeIP(a)
-	bb := ipToInt(b)
+	normalizedB := normalizeIP(b)
-	return aa.Cmp(bb)
+
+	if len(normalizedA) == len(normalizedB) && len(normalizedA) != 0 {
+		return ipToInt(normalizedA).Cmp(ipToInt(normalizedB))
+	}
+
+	return -2
 }
 
 func ipToInt(ip net.IP) *big.Int {
-	if v := ip.To4(); v != nil {
+	return big.NewInt(0).SetBytes(ip)
-		return big.NewInt(0).SetBytes(v)
+}
+
+func intToIP(i *big.Int, isIPv6 bool) net.IP {
+	intBytes := i.Bytes()
+
+	if len(intBytes) == net.IPv4len || len(intBytes) == net.IPv6len {
+		return intBytes
 	}
-	return big.NewInt(0).SetBytes(ip.To16())
+
+	if isIPv6 {
+		return append(make([]byte, net.IPv6len-len(intBytes)), intBytes...)
+	}
+
+	return append(make([]byte, net.IPv4len-len(intBytes)), intBytes...)
 }
 
-func intToIP(i *big.Int) net.IP {
+// normalizeIP will normalize IP by family,
-	return net.IP(i.Bytes())
+// IPv4 : 4-byte form
+// IPv6 : 16-byte form
+// others : nil
+func normalizeIP(ip net.IP) net.IP {
+	if ipTo4 := ip.To4(); ipTo4 != nil {
+		return ipTo4
+	}
+	return ip.To16()
 }
 
-// Network masks off the host portion of the IP
+// Network masks off the host portion of the IP, if IPNet is invalid,
+// return nil
 func Network(ipn *net.IPNet) *net.IPNet {
+	if ipn == nil {
+		return nil
+	}
+
+	maskedIP := ipn.IP.Mask(ipn.Mask)
+	if maskedIP == nil {
+		return nil
+	}
+
 	return &net.IPNet{
-		IP:   ipn.IP.Mask(ipn.Mask),
+		IP:   maskedIP,
 		Mask: ipn.Mask,
 	}
 }

pkg/ip/cidr_test.go

@@ -0,0 +1,247 @@
+// Copyright 2022 CNI authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package ip
+
+import (
+	"net"
+
+	. "github.com/onsi/ginkgo"
+	. "github.com/onsi/gomega"
+)
+
+var _ = Describe("CIDR functions", func() {
+	It("NextIP", func() {
+		testCases := []struct {
+			ip     net.IP
+			nextIP net.IP
+		}{
+			{
+				[]byte{192, 0, 2},
+				nil,
+			},
+			{
+				net.ParseIP("192.168.0.1"),
+				net.IPv4(192, 168, 0, 2).To4(),
+			},
+			{
+				net.ParseIP("192.168.0.255"),
+				net.IPv4(192, 168, 1, 0).To4(),
+			},
+			{
+				net.ParseIP("0.1.0.5"),
+				net.IPv4(0, 1, 0, 6).To4(),
+			},
+			{
+				net.ParseIP("AB12::123"),
+				net.ParseIP("AB12::124"),
+			},
+			{
+				net.ParseIP("AB12::FFFF"),
+				net.ParseIP("AB12::1:0"),
+			},
+			{
+				net.ParseIP("0::123"),
+				net.ParseIP("0::124"),
+			},
+		}
+
+		for _, test := range testCases {
+			ip := NextIP(test.ip)
+
+			Expect(ip).To(Equal(test.nextIP))
+		}
+	})
+
+	It("PrevIP", func() {
+		testCases := []struct {
+			ip     net.IP
+			prevIP net.IP
+		}{
+			{
+				[]byte{192, 0, 2},
+				nil,
+			},
+			{
+				net.ParseIP("192.168.0.2"),
+				net.IPv4(192, 168, 0, 1).To4(),
+			},
+			{
+				net.ParseIP("192.168.1.0"),
+				net.IPv4(192, 168, 0, 255).To4(),
+			},
+			{
+				net.ParseIP("0.1.0.5"),
+				net.IPv4(0, 1, 0, 4).To4(),
+			},
+			{
+				net.ParseIP("AB12::123"),
+				net.ParseIP("AB12::122"),
+			},
+			{
+				net.ParseIP("AB12::1:0"),
+				net.ParseIP("AB12::FFFF"),
+			},
+			{
+				net.ParseIP("0::124"),
+				net.ParseIP("0::123"),
+			},
+		}
+
+		for _, test := range testCases {
+			ip := PrevIP(test.ip)
+
+			Expect(ip).To(Equal(test.prevIP))
+		}
+	})
+
+	It("Cmp", func() {
+		testCases := []struct {
+			a      net.IP
+			b      net.IP
+			result int
+		}{
+			{
+				net.ParseIP("192.168.0.2"),
+				nil,
+				-2,
+			},
+			{
+				net.ParseIP("192.168.0.2"),
+				[]byte{192, 168, 5},
+				-2,
+			},
+			{
+				net.ParseIP("192.168.0.2"),
+				net.ParseIP("AB12::123"),
+				-2,
+			},
+			{
+				net.ParseIP("192.168.0.2"),
+				net.ParseIP("192.168.0.5"),
+				-1,
+			},
+			{
+				net.ParseIP("192.168.0.2"),
+				net.ParseIP("192.168.0.5").To4(),
+				-1,
+			},
+			{
+				net.ParseIP("192.168.0.10"),
+				net.ParseIP("192.168.0.5"),
+				1,
+			},
+			{
+				net.ParseIP("192.168.0.10"),
+				net.ParseIP("192.168.0.10"),
+				0,
+			},
+			{
+				net.ParseIP("192.168.0.10"),
+				net.ParseIP("192.168.0.10").To4(),
+				0,
+			},
+			{
+				net.ParseIP("AB12::122"),
+				net.ParseIP("AB12::123"),
+				-1,
+			},
+			{
+				net.ParseIP("AB12::210"),
+				net.ParseIP("AB12::123"),
+				1,
+			},
+			{
+				net.ParseIP("AB12::210"),
+				net.ParseIP("AB12::210"),
+				0,
+			},
+		}
+
+		for _, test := range testCases {
+			result := Cmp(test.a, test.b)
+
+			Expect(result).To(Equal(test.result))
+		}
+	})
+
+	It("Network", func() {
+		testCases := []struct {
+			ipNet  *net.IPNet
+			result *net.IPNet
+		}{
+			{
+				nil,
+				nil,
+			},
+			{
+				&net.IPNet{
+					IP:   nil,
+					Mask: net.IPv4Mask(255, 255, 255, 0),
+				},
+				nil,
+			},
+			{
+				&net.IPNet{
+					IP:   net.IPv4(192, 168, 0, 1),
+					Mask: nil,
+				},
+				nil,
+			},
+			{
+				&net.IPNet{
+					IP:   net.ParseIP("AB12::123"),
+					Mask: net.IPv4Mask(255, 255, 255, 0),
+				},
+				nil,
+			},
+			{
+				&net.IPNet{
+					IP:   net.IPv4(192, 168, 0, 100).To4(),
+					Mask: net.CIDRMask(120, 128),
+				},
+				&net.IPNet{
+					IP:   net.IPv4(192, 168, 0, 0).To4(),
+					Mask: net.CIDRMask(120, 128),
+				},
+			},
+			{
+				&net.IPNet{
+					IP:   net.IPv4(192, 168, 0, 100),
+					Mask: net.CIDRMask(24, 32),
+				},
+				&net.IPNet{
+					IP:   net.IPv4(192, 168, 0, 0).To4(),
+					Mask: net.CIDRMask(24, 32),
+				},
+			},
+			{
+				&net.IPNet{
+					IP:   net.ParseIP("AB12::123"),
+					Mask: net.CIDRMask(120, 128),
+				},
+				&net.IPNet{
+					IP:   net.ParseIP("AB12::100"),
+					Mask: net.CIDRMask(120, 128),
+				},
+			},
+		}
+
+		for _, test := range testCases {
+			result := Network(test.ipNet)
+
+			Expect(result).To(Equal(test.result))
+		}
+	})
+})