IterateForAssignment: Properly handle invalid syntax for exclude range

pkg/allocate/allocate.go

@@ -102,10 +102,14 @@ func IterateForAssignment(ipnet net.IPNet, rangeStart net.IP, rangeEnd net.IP, r
 	for _, r := range reserveList {
 		reserved[r.IP.String()] = true
 	}
+
 	// Build excluded list, "192.168.2.229/30", "192.168.1.229/30".
 	excluded := []*net.IPNet{}
 	for _, v := range excludeRanges {
-		_, subnet, _ := net.ParseCIDR(v)
+		subnet, err := parseExcludedRange(v)
+		if err != nil {
+			return net.IP{}, reserveList, fmt.Errorf("could not parse exclude range, err: %q", err)
+		}
 		excluded = append(excluded, subnet)
 	}
 
@@ -144,3 +148,28 @@ func skipExcludedSubnets(ip net.IP, excluded []*net.IPNet) net.IP {
 	}
 	return nil
 }
+
+// parseExcludedRange parses a provided string to a net.IPNet.
+// If the provided string is a valid CIDR, return the net.IPNet for that CIDR.
+// If the provided string is a valid IP address, add the /32 or /128 prefix to form the CIDR and return the net.IPNet.
+// Otherwise, return the error.
+func parseExcludedRange(s string) (*net.IPNet, error) {
+	// Try parsing CIDRs.
+	_, subnet, err := net.ParseCIDR(s)
+	if err == nil {
+		return subnet, nil
+	}
+	// The user might have given a single IP address, try parsing that - if it does not parse, return the error that
+	// we got earlier.
+	ip := net.ParseIP(s)
+	if ip == nil {
+		return nil, err
+	}
+	// If the address parses, check if it's IPv4 or IPv6 and add the correct prefix.
+	if ip.To4() != nil {
+		_, subnet, err = net.ParseCIDR(fmt.Sprintf("%s/32", s))
+	} else {
+		_, subnet, err = net.ParseCIDR(fmt.Sprintf("%s/128", s))
+	}
+	return subnet, err
+}

pkg/allocate/allocate_test.go

@@ -113,6 +113,33 @@ var _ = Describe("Allocation operations", func() {
 
 	})
 
+	It("can IterateForAssignment on an IPv4 address excluding a range which is a single IP", func() {
+		firstip, ipnet, err := net.ParseCIDR("192.168.0.0/29")
+		Expect(err).NotTo(HaveOccurred())
+
+		// figure out the range start.
+		calculatedrangestart := net.ParseIP(firstip.Mask(ipnet.Mask).String())
+
+		var ipres []types.IPReservation
+		exrange := []string{"192.168.0.1"}
+		newip, _, err := IterateForAssignment(*ipnet, calculatedrangestart, nil, ipres, exrange, "0xdeadbeef", "")
+		Expect(err).NotTo(HaveOccurred())
+		Expect(fmt.Sprint(newip)).To(Equal("192.168.0.2"))
+	})
+
+	It("correctly handles invalid syntax for an exclude range with IPv4", func() {
+		firstip, ipnet, err := net.ParseCIDR("192.168.0.0/29")
+		Expect(err).NotTo(HaveOccurred())
+
+		// figure out the range start.
+		calculatedrangestart := net.ParseIP(firstip.Mask(ipnet.Mask).String())
+
+		var ipres []types.IPReservation
+		exrange := []string{"192.168.0.1/123"}
+		_, _, err = IterateForAssignment(*ipnet, calculatedrangestart, nil, ipres, exrange, "0xdeadbeef", "")
+		Expect(err).To(MatchError(HavePrefix("could not parse exclude range")))
+	})
+
 	It("can IterateForAssignment on an IPv6 address excluding a range", func() {
 
 		firstip, ipnet, err := net.ParseCIDR("100::2:1/125")
@@ -128,6 +155,32 @@ var _ = Describe("Allocation operations", func() {
 
 	})
 
+	It("can IterateForAssignment on an IPv6 address excluding a range which is a single IP", func() {
+		firstip, ipnet, err := net.ParseCIDR("100::2:1/125")
+		Expect(err).NotTo(HaveOccurred())
+
+		// figure out the range start.
+		calculatedrangestart := net.ParseIP(firstip.Mask(ipnet.Mask).String())
+
+		var ipres []types.IPReservation
+		exrange := []string{"100::2:1"}
+		newip, _, _ := IterateForAssignment(*ipnet, calculatedrangestart, nil, ipres, exrange, "0xdeadbeef", "")
+		Expect(fmt.Sprint(newip)).To(Equal("100::2:2"))
+	})
+
+	It("correctly handles invalid syntax for an exclude range with IPv6", func() {
+		firstip, ipnet, err := net.ParseCIDR("100::2:1/125")
+		Expect(err).NotTo(HaveOccurred())
+
+		// figure out the range start.
+		calculatedrangestart := net.ParseIP(firstip.Mask(ipnet.Mask).String())
+
+		var ipres []types.IPReservation
+		exrange := []string{"100::2::1"}
+		_, _, err = IterateForAssignment(*ipnet, calculatedrangestart, nil, ipres, exrange, "0xdeadbeef", "")
+		Expect(err).To(MatchError(HavePrefix("could not parse exclude range")))
+	})
+
 	It("can IterateForAssignment on an IPv6 address excluding a very large range", func() {
 
 		firstip, ipnet, err := net.ParseCIDR("2001:db8::/30")