Add Next/PreviousSubnet() to netutil pkg

* Add Next/PreviousSubnet() * Add these examples
cloud-barista · Jan 12, 2024 · b1c8471 · b1c8471
1 parent 8ca744c
commit b1c8471
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diff --git a/src/core/common/netutil/netutil.go b/src/core/common/netutil/netutil.go
@@ -429,3 +429,75 @@ func cidrOverlap(cidr1, cidr2 string) bool {
 	_, net2, _ := net.ParseCIDR(cidr2)
 	return net1.Contains(net2.IP) || net2.Contains(net1.IP)
 }
+
+// ///////////////////////////////////////////////////////////////////////////////////
+// NextSubnet find and check the next subnet based on the base/parent network.
+func NextSubnet(currentSubnetCIDR string, baseNetworkCIDR string) (string, error) {
+	// Parse the current subnet
+	_, currentNet, err := net.ParseCIDR(currentSubnetCIDR)
+	if err != nil {
+		return "", err
+	}
+
+	// Parse the base network
+	_, baseNet, err := net.ParseCIDR(baseNetworkCIDR)
+	if err != nil {
+		return "", err
+	}
+
+	// Convert the current subnet's IP to uint32
+	currentIPInt := IpToUint32(currentNet.IP)
+
+	// Calculate the size of the current subnet
+	maskSize, _ := currentNet.Mask.Size()
+	subnetSize := uint32(1 << (32 - maskSize))
+
+	// Calculate the next subnet's starting IP
+	nextIPInt := currentIPInt + subnetSize
+
+	// Convert the next IP to net.IP
+	nextIP := Uint32ToIP(nextIPInt)
+
+	// Check if the next subnet is within the base network range
+	if !baseNet.Contains(nextIP) {
+		return "", fmt.Errorf("the next subnet is outside the base network range")
+	}
+
+	return fmt.Sprintf("%s/%d", nextIP.String(), maskSize), nil
+}
+
+
+// PreviousSubnet find and check the previous subnet based on the base/parent network.
+func PreviousSubnet(currentSubnet string, baseNetworkCIDR string) (string, error) {
+	// Parse the current subnet
+	_, currentNet, err := net.ParseCIDR(currentSubnet)
+	if err != nil {
+		return "", err
+	}
+
+	// Parse the base network
+	_, baseNet, err := net.ParseCIDR(baseNetworkCIDR)
+	if err != nil {
+		return "", err
+	}
+
+	// Convert the current subnet's IP to uint32
+	currentIPInt := IpToUint32(currentNet.IP)
+
+	// Calculate the size of the current subnet
+	maskSize, _ := currentNet.Mask.Size()
+	subnetSize := uint32(1 << (32 - maskSize))
+
+	// Calculate the previous subnet's starting IP
+	previousIPInt := currentIPInt - subnetSize
+
+	// Convert the previous IP to net.IP
+	previousIP := Uint32ToIP(previousIPInt)
+
+	// Check if the previous subnet is within the base network range
+	if !baseNet.Contains(previousIP) {
+		return "", fmt.Errorf("the previous subnet is outside the base network range")
+	}
+
+	return fmt.Sprintf("%s/%d", previousIP.String(), maskSize), nil
+}
diff --git a/src/examples/netutil/netutil.go b/src/examples/netutil/netutil.go
@@ -217,4 +217,80 @@ func runExample(cmd *cobra.Command, args []string) {
 	}
 	fmt.Printf("[Subnetting result]\n%s\n", string(pretty))
 
+	///////////////////////////////////////////////////////////////////////////////////////////////////
+	fmt.Println("\n\nNextSubnet() test example")
+
+	baseNetwork := "10.0.0.0/16"
+	currentSubnet0 := "10.0.0.0/18"
+	currentSubnet1 := "10.0.64.0/18"
+	currentSubnet2 := "10.0.128.0/18"
+	currentSubnet3 := "10.0.192.0/18"
+
+	fmt.Printf("[NextSubnet() Case1] Base Network CIDR: %s, Current Subnet CIDR: %s\n", baseNetwork, currentSubnet0)
+	nextSubnet, err := netutil.NextSubnet(currentSubnet0, baseNetwork)
+	if err != nil {
+		fmt.Println(" Error:", err)
+	} else {
+		fmt.Println(" Next Subnet:", nextSubnet)
+	}
+
+	fmt.Printf("[NextSubnet() Case2] Base Network CIDR: %s, Current Subnet CIDR: %s\n", baseNetwork, currentSubnet1)
+	nextSubnet, err = netutil.NextSubnet(currentSubnet1, baseNetwork)
+	if err != nil {
+		fmt.Println(" Error:", err)
+	} else {
+		fmt.Println(" Next Subnet:", nextSubnet)
+	}
+
+	fmt.Printf("[NextSubnet() Case3] Base Network CIDR: %s, Current Subnet CIDR: %s\n", baseNetwork, currentSubnet2)
+	nextSubnet, err = netutil.NextSubnet(currentSubnet2, baseNetwork)
+	if err != nil {
+		fmt.Println(" Error:", err)
+	} else {
+		fmt.Println(" Next Subnet:", nextSubnet)
+	}
+
+	fmt.Printf("[NextSubnet() Case4] Base Network CIDR: %s, Current Subnet CIDR: %s\n", baseNetwork, currentSubnet3)
+	nextSubnet, err = netutil.NextSubnet(currentSubnet3, baseNetwork)
+	if err != nil {
+		fmt.Println(" Error:", err)
+	} else {
+		fmt.Println(" Next Subnet:", nextSubnet)
+	}
+
+	///////////////////////////////////////////////////////////////////////////////////////////////////
+	fmt.Println("\n\nPreviousSubnet() test example")
+
+	fmt.Printf("[PreviousSubnet() Case1] Base Network CIDR: %s, Current Subnet CIDR: %s\n", baseNetwork, currentSubnet0)
+	previousSubnet, err := netutil.PreviousSubnet(currentSubnet0, baseNetwork)
+	if err != nil {
+		fmt.Println(" Error:", err)
+	} else {
+		fmt.Println(" Previous Subnet:", previousSubnet)
+	}
+
+	fmt.Printf("[PreviousSubnet() Case2] Base Network CIDR: %s, Current Subnet CIDR: %s\n", baseNetwork, currentSubnet1)
+	previousSubnet, err = netutil.PreviousSubnet(currentSubnet1, baseNetwork)
+	if err != nil {
+		fmt.Println(" Error:", err)
+	} else {
+		fmt.Println(" Previous Subnet:", previousSubnet)
+	}
+
+	fmt.Printf("[PreviousSubnet() Case3] Base Network CIDR: %s, Current Subnet CIDR: %s\n", baseNetwork, currentSubnet2)
+	previousSubnet, err = netutil.PreviousSubnet(currentSubnet2, baseNetwork)
+	if err != nil {
+		fmt.Println(" Error:", err)
+	} else {
+		fmt.Println(" Previous Subnet:", previousSubnet)
+	}
+
+	fmt.Printf("[PreviousSubnet() Case4] Base Network CIDR: %s, Current Subnet CIDR: %s\n", baseNetwork, currentSubnet3)
+	previousSubnet, err = netutil.PreviousSubnet(currentSubnet3, baseNetwork)
+	if err != nil {
+		fmt.Println(" Error:", err)
+	} else {
+		fmt.Println(" Previous Subnet:", previousSubnet)
+	}
+
 }