Parse and validate subnet ranges

util/config.go

@@ -1,24 +1,31 @@
 package util
 
-import "strings"
+import (
+	"net"
+	"strings"
+
+	"github.com/labstack/gommon/log"
+)
 
 // Runtime config
 var (
-	DisableLogin   bool
-	BindAddress    string
-	SmtpHostname   string
-	SmtpPort       int
-	SmtpUsername   string
-	SmtpPassword   string
-	SmtpNoTLSCheck bool
-	SmtpEncryption string
-	SmtpAuthType   string
-	SendgridApiKey string
-	EmailFrom      string
-	EmailFromName  string
-	SessionSecret  []byte
-	WgConfTemplate string
-	BasePath       string
+	DisableLogin      bool
+	BindAddress       string
+	SmtpHostname      string
+	SmtpPort          int
+	SmtpUsername      string
+	SmtpPassword      string
+	SmtpNoTLSCheck    bool
+	SmtpEncryption    string
+	SmtpAuthType      string
+	SendgridApiKey    string
+	EmailFrom         string
+	EmailFromName     string
+	SessionSecret     []byte
+	WgConfTemplate    string
+	BasePath          string
+	SubnetRanges      map[string]([]*net.IPNet)
+	SubnetRangesOrder []string
 )
 
 const (
@@ -66,3 +73,45 @@ func ParseBasePath(basePath string) string {
 	}
 	return basePath
 }
+
+func ParseSubnetRanges(subnetRangesStr string) map[string]([]*net.IPNet) {
+	subnetRanges := map[string]([]*net.IPNet){}
+	if subnetRangesStr == "" {
+		return subnetRanges
+	}
+	cidrSet := map[string]bool{}
+	subnetRangesStr = strings.TrimSpace(subnetRangesStr)
+	subnetRangesStr = strings.Trim(subnetRangesStr, ";:,")
+	ranges := strings.Split(subnetRangesStr, ";")
+	for _, rng := range ranges {
+		rng = strings.TrimSpace(rng)
+		rngSpl := strings.Split(rng, ":")
+		if len(rngSpl) != 2 {
+			log.Warnf("Unable to parse subnet range: %v. Skipped.", rng)
+			continue
+		}
+		rngName := strings.TrimSpace(rngSpl[0])
+		subnetRanges[rngName] = make([]*net.IPNet, 0)
+		cidrs := strings.Split(rngSpl[1], ",")
+		for _, cidr := range cidrs {
+			cidr = strings.TrimSpace(cidr)
+			_, net, err := net.ParseCIDR(cidr)
+			if err != nil {
+				log.Warnf("[%v] Unable to parse CIDR: %v. Skipped.", rngName, cidr)
+				continue
+			}
+			if cidrSet[net.String()] {
+				log.Warnf("[%v] CIDR already exists: %v. Skipped.", rngName, net.String())
+				continue
+			}
+			cidrSet[net.String()] = true
+			subnetRanges[rngName] = append(subnetRanges[rngName], net)
+		}
+		if len(subnetRanges[rngName]) == 0 {
+			delete(subnetRanges, rngName)
+		} else {
+			SubnetRangesOrder = append(SubnetRangesOrder, rngName)
+		}
+	}
+	return subnetRanges
+}

util/util.go

@@ -95,6 +95,15 @@ func ClientDefaultsFromEnv() model.ClientDefaults {
 	return clientDefaults
 }
 
+// ContainsCIDR to check if ipnet1 contains ipnet2
+// https://stackoverflow.com/a/40406619/6111641
+// https://go.dev/play/p/Q4J-JEN3sF
+func ContainsCIDR(ipnet1, ipnet2 *net.IPNet) bool {
+	ones1, _ := ipnet1.Mask.Size()
+	ones2, _ := ipnet2.Mask.Size()
+	return ones1 <= ones2 && ipnet1.Contains(ipnet2.IP)
+}
+
 // ValidateCIDR to validate a network CIDR
 func ValidateCIDR(cidr string) bool {
 	_, _, err := net.ParseCIDR(cidr)
@@ -384,6 +393,88 @@ func ValidateIPAllocation(serverAddresses []string, ipAllocatedList []string, ip
 	return true, nil
 }
 
+// ValidateAndFixSubnetRanges to check if subnet ranges are valid for the server configuration
+// Removes all non-valid CIDRs
+func ValidateAndFixSubnetRanges(db store.IStore) error {
+	if len(SubnetRangesOrder) == 0 {
+		return nil
+	}
+
+	server, err := db.GetServer()
+	if err != nil {
+		return err
+	}
+	var serverSubnets []*net.IPNet
+	for _, addr := range server.Interface.Addresses {
+		addr = strings.TrimSpace(addr)
+		_, net, err := net.ParseCIDR(addr)
+		if err != nil {
+			return err
+		}
+		serverSubnets = append(serverSubnets, net)
+	}
+
+	for _, rng := range SubnetRangesOrder {
+		cidrs := SubnetRanges[rng]
+		if len(cidrs) > 0 {
+			newCIDRs := make([]*net.IPNet, 0)
+			for _, cidr := range cidrs {
+				valid := false
+
+				for _, serverSubnet := range serverSubnets {
+					if ContainsCIDR(serverSubnet, cidr) {
+						valid = true
+						break
+					}
+				}
+
+				if valid {
+					newCIDRs = append(newCIDRs, cidr)
+				} else {
+					log.Warnf("[%v] CIDR is outside of all server subnets: %v. Removed.", rng, cidr)
+				}
+			}
+
+			if len(newCIDRs) > 0 {
+				SubnetRanges[rng] = newCIDRs
+			} else {
+				delete(SubnetRanges, rng)
+				log.Warnf("[%v] No valid CIDRs in this subnet range. Removed.", rng)
+			}
+		}
+	}
+
+	return nil
+}
+
+// GetSubnetRangesString to get a formatted string, representing active subnet ranges
+func GetSubnetRangesString() string {
+	if len(SubnetRangesOrder) == 0 {
+		return ""
+	}
+
+	strB := strings.Builder{}
+
+	for _, rng := range SubnetRangesOrder {
+		cidrs := SubnetRanges[rng]
+		if len(cidrs) > 0 {
+			strB.WriteString(rng)
+			strB.WriteString(":[")
+			first := true
+			for _, cidr := range cidrs {
+				if !first {
+					strB.WriteString(", ")
+				}
+				strB.WriteString(cidr.String())
+				first = false
+			}
+			strB.WriteString("]  ")
+		}
+	}
+
+	return strings.TrimSpace(strB.String())
+}
+
 // WriteWireGuardServerConfig to write Wireguard server config. e.g. wg0.conf
 func WriteWireGuardServerConfig(tmplDir fs.FS, serverConfig model.Server, clientDataList []model.ClientData, usersList []model.User, globalSettings model.GlobalSetting) error {
 	var tmplWireguardConf string