Add feature to add next free IP

cmd/classes.go

@@ -6,6 +6,7 @@ package cmd
 
 import (
 	"errors"
+	"math"
 	"net/netip"
 	"time"
 )
@@ -19,6 +20,21 @@ type Subnet struct {
 	Addresses []Address    `json:"addresses"`
 }
 
+// GetIPCount gets the IP count for the Subnet
+//
+// Returns the IP count or -1 if it's a IPv6 prefix
+func (s Subnet) GetIPCount() int {
+	if !s.Subnet.Addr().Is4() {
+		return -1
+	}
+	hostbits := float64(32 - s.Subnet.Bits())
+	if s.Subnet.Bits() == 31 {
+		return 2
+	} else {
+		return int(math.Pow(2, hostbits)) - 2
+	}
+}
+
 // HasIP checks if a Subnet already contains given netip.Addr.
 // Returns true if the IP already is present, false otherwise.
 func (s Subnet) HasIP(ip netip.Addr) bool {
@@ -33,6 +49,42 @@ func (s Subnet) HasIP(ip netip.Addr) bool {
 	return iscontained
 }
 
+// FindFirstFreeIP finds and returns the next free netip.Addr
+// or an invalid netip.Addr if no free IP was found
+func (s Subnet) FindFirstFreeIP() netip.Addr {
+	var ip netip.Addr
+
+	if s.Subnet.Addr().Is4() {
+		subnetips := s.GetIPCount()
+
+		// handling /31 prefixes
+		if subnetips == 2 {
+			ip = s.Subnet.Addr()
+		} else {
+			ip = s.Subnet.Addr().Next()
+		}
+
+		// start at first free IP
+		for count := 0; count < subnetips; count++ {
+
+			if s.HasIP(ip) {
+				ip = ip.Next()
+			} else {
+				return ip
+			}
+		}
+	} else {
+		ip = s.Subnet.Addr().Next()
+		for ; s.Subnet.Contains(ip); ip = ip.Next() {
+			if !s.HasIP(ip) {
+				return ip
+			}
+		}
+	}
+
+	return netip.Addr{}
+}
+
 // RemoveIP removes the Address object for given ip from
 // the Address list of the subnet.
 //

cmd/ip-add.go

@@ -15,67 +15,80 @@ import (
 )
 
 var ipaddCmd = &cobra.Command{
-	Use:     "add ipaddress [hostname]",
+	Use:     "add ipaddress|subnet [hostname]",
 	Short:   "Add new IP address",
-	Long:    `Add new IP address`,
+	Long:    `Adds a new IP address OR the next free IP address from a subnet`,
 	Aliases: []string{"a"},
 	Args:    cobra.RangeArgs(1, 2),
 	Run: func(cmd *cobra.Command, args []string) {
-		var ipaddress, hostname string
+		var iparg, hostname string
 
 		if len(args) == 1 {
-			ipaddress = args[0]
+			iparg = args[0]
 			hostname = ""
 		} else {
-			ipaddress = args[0]
+			iparg = args[0]
 			hostname = args[1]
 		}
 
-		ip, parseerr := netip.ParseAddr(ipaddress)
+		var bestsubnet Subnet
+		var ip netip.Addr
 
-		// Exit if parsed value is no valid IP
-		if parseerr != nil {
-			fmt.Println("[ERROR]", parseerr)
+		argip, ipparseerr := netip.ParseAddr(iparg)
+		argsubnet, subparseerr := netip.ParsePrefix(iparg)
+
+		if ipparseerr != nil && subparseerr != nil {
+			fmt.Printf("[ERROR] Argument is neither a valid IP address nor a valid Subnet: %v", iparg)
 			os.Exit(1)
-		}
+		} else if ipparseerr == nil && subparseerr != nil {
+			// argument was a single IP
+			var subnetexists bool
+			bestsubnet, subnetexists = FindBestSubnet(argip)
+			if !subnetexists {
+				fmt.Printf("[ERROR] Found no suitable subnet for IP %v\n", iparg)
+				fmt.Printf("[ERROR] Maybe you need to add it first?\n")
+				os.Exit(1)
+			}
+			if bestsubnet.HasIP(argip) {
+				fmt.Printf("[ERROR] IP %v already exists in subnet %v\n", argip.String(), bestsubnet.Subnet.String())
+				os.Exit(1)
+			}
+			ip = argip
 
-		// Exit if parsed value is an IPv6 Address
-		// TODO: Implement IPv6 support
-		//if !ip.Is4() {
-		//    fmt.Printf("[ERROR] IPv6 is not yet supported!\n")
-		//    os.Exit(1)
-		//}
+		} else if subparseerr == nil && ipparseerr != nil {
+			// argument was a subnet
+			var subneterr error
+			bestsubnet, subneterr = GetSubnet(argsubnet)
+			if subneterr != nil {
+				fmt.Println("[ERROR]", subneterr)
+				os.Exit(1)
+			}
+			ip = bestsubnet.FindFirstFreeIP()
 
-		subnet, subnetexists := FindBestSubnet(ip)
+			if !ip.IsValid() {
+				fmt.Printf("[ERROR] Found no free IP in Subnet %v\n", argsubnet.String())
+				os.Exit(1)
+			}
 
-		if !subnetexists {
-			fmt.Printf("[ERROR] Found no suitable subnet for IP %v\n", ipaddress)
-			fmt.Printf("[ERROR] Maybe you need to add it first?\n")
-			os.Exit(1)
-		}
-
-		if subnet.HasIP(ip) {
-			fmt.Printf("[ERROR] IP %v already exists in subnet %v\n", ip.String(), subnet.Subnet.String())
-			os.Exit(1)
 		}
 
 		currentuser, _ := user.Current()
 		timestamp := time.Now()
 
-		subnet.Addresses = append(subnet.Addresses, Address{ip, hostname, timestamp, currentuser.Username})
-		subnet.ChangedBy = currentuser.Username
-		subnet.ChangedAt = timestamp
+		bestsubnet.Addresses = append(bestsubnet.Addresses, Address{ip, hostname, timestamp, currentuser.Username})
+		bestsubnet.ChangedBy = currentuser.Username
+		bestsubnet.ChangedAt = timestamp
 
-		writeerr := subnet.WriteSubnet()
+		writeerr := bestsubnet.WriteSubnet()
 		if writeerr != nil {
 			fmt.Println("[ERROR]", writeerr)
 			os.Exit(1)
 		}
 
 		if hostname == "" {
-			fmt.Printf("added ip:\nip: %v\n", ipaddress)
+			fmt.Printf("added ip:\nip: %v\n", ip.String())
 		} else {
-			fmt.Printf("added ip:\nip: %v\nhostname: %v\n", ipaddress, hostname)
+			fmt.Printf("added ip:\nip: %v\nhostname: %v\n", ip.String(), hostname)
 			dnserr := AddDNSFqdn(hostname, ip)
 			if dnserr != nil {
 				fmt.Println("[ERROR]", dnserr)

cmd/storage.go

@@ -114,7 +114,13 @@ func (s Subnet) WriteSubnet() error {
 		fmt.Println("[ERROR]", fileerr)
 		os.Exit(1)
 	}
-	defer file.Close()
+	defer func(file *os.File) {
+		err := file.Close()
+		if err != nil {
+			fmt.Println("[ERROR]", err)
+			os.Exit(1)
+		}
+	}(file)
 
 	_, writeerr := file.Write(data)
 	if writeerr != nil {
@@ -137,12 +143,12 @@ func GetSubnet(net netip.Prefix) (Subnet, error) {
 
 	content, readerr := os.ReadFile(filename)
 	if readerr != nil {
-		return Subnet{}, readerr
+		return Subnet{}, fmt.Errorf("can't open file for subnet %v for reading", net.String())
 	}
 
 	marsherr := json.Unmarshal(content, &subnet)
 	if marsherr != nil {
-		return Subnet{}, marsherr
+		return Subnet{}, fmt.Errorf("can't unmarshal file contents of file %v\n%v", filename, marsherr)
 	}
 
 	return subnet, nil