Added --subnet validation

cmd/minikube/cmd/start.go

@@ -47,6 +47,7 @@ import (
 	"golang.org/x/text/cases"
 	"golang.org/x/text/language"
 	"k8s.io/minikube/pkg/minikube/command"
+	netutil "k8s.io/minikube/pkg/network"
 
 	"k8s.io/klog/v2"
 	cmdcfg "k8s.io/minikube/cmd/minikube/cmd/config"
@@ -1212,32 +1213,19 @@ func validateFlags(cmd *cobra.Command, drvName string) {
 
 	}
 
-	if cmd.Flags().Changed(containerRuntime) {
-		err := validateRuntime(viper.GetString(containerRuntime))
+	if cmd.Flags().Changed(subnet) {
+		err := validateSubnet(viper.GetString(subnet))
 		if err != nil {
 			exit.Message(reason.Usage, "{{.err}}", out.V{"err": err})
 		}
-		validateCNI(cmd, viper.GetString(containerRuntime))
 	}
 
-	if driver.BareMetal(drvName) {
-		if ClusterFlagValue() != constants.DefaultClusterName {
-			exit.Message(reason.DrvUnsupportedProfile, "The '{{.name}} driver does not support multiple profiles: https://minikube.sigs.k8s.io/docs/reference/drivers/none/", out.V{"name": drvName})
-		}
-
-		// default container runtime varies, starting with Kubernetes 1.24 - assume that only the default container runtime has been tested
-		rtime := viper.GetString(containerRuntime)
-		if rtime != constants.DefaultContainerRuntime && rtime != defaultRuntime(getKubernetesVersion(nil)) {
-			out.WarningT("Using the '{{.runtime}}' runtime with the 'none' driver is an untested configuration!", out.V{"runtime": rtime})
-		}
-
-		// conntrack is required starting with Kubernetes 1.18, include the release candidates for completion
-		version, _ := util.ParseKubernetesVersion(getKubernetesVersion(nil))
-		if version.GTE(semver.MustParse("1.18.0-beta.1")) {
-			if _, err := exec.LookPath("conntrack"); err != nil {
-				exit.Message(reason.GuestMissingConntrack, "Sorry, Kubernetes {{.k8sVersion}} requires conntrack to be installed in root's path", out.V{"k8sVersion": version.String()})
-			}
+	if cmd.Flags().Changed(containerRuntime) {
+		err := validateRuntime(viper.GetString(containerRuntime))
+		if err != nil {
+			exit.Message(reason.Usage, "{{.err}}", out.V{"err": err})
 		}
+		validateCNI(cmd, viper.GetString(containerRuntime))
 	}
 
 	if driver.IsSSH(drvName) {
@@ -1279,6 +1267,7 @@ func validateFlags(cmd *cobra.Command, drvName string) {
 		exit.Message(reason.Usage, "Sorry, please set the --output flag to one of the following valid options: [text,json]")
 	}
 
+	validateBareMetal(drvName)
 	validateRegistryMirror()
 	validateInsecureRegistry()
 }
@@ -1763,6 +1752,50 @@ func validateDockerStorageDriver(drvName string) {
 	viper.Set(preload, false)
 }
 
+// validateSubnet checks that the subnet provided has a private IP
+// and does not have a mask of more that /30
+func validateSubnet(subnet string) error {
+	ip, cidr, err := netutil.ParseAddr(subnet)
+	if err != nil {
+		return errors.Errorf("Sorry, unable to parse subnet: %v", err)
+	}
+	if !ip.IsPrivate() {
+		return errors.Errorf("Sorry, the subnet %s is not a private IP", ip)
+	}
+
+	if cidr != nil {
+		mask, _ := cidr.Mask.Size()
+		if mask > 30 {
+			return errors.Errorf("Sorry, the subnet provided does not have a mask less than or equal to /30")
+		}
+	}
+	return nil
+}
+
+func validateBareMetal(drvName string) {
+	if !driver.BareMetal(drvName) {
+		return
+	}
+
+	if ClusterFlagValue() != constants.DefaultClusterName {
+		exit.Message(reason.DrvUnsupportedProfile, "The '{{.name}} driver does not support multiple profiles: https://minikube.sigs.k8s.io/docs/reference/drivers/none/", out.V{"name": drvName})
+	}
+
+	// default container runtime varies, starting with Kubernetes 1.24 - assume that only the default container runtime has been tested
+	rtime := viper.GetString(containerRuntime)
+	if rtime != constants.DefaultContainerRuntime && rtime != defaultRuntime(getKubernetesVersion(nil)) {
+		out.WarningT("Using the '{{.runtime}}' runtime with the 'none' driver is an untested configuration!", out.V{"runtime": rtime})
+	}
+
+	// conntrack is required starting with Kubernetes 1.18, include the release candidates for completion
+	version, _ := util.ParseKubernetesVersion(getKubernetesVersion(nil))
+	if version.GTE(semver.MustParse("1.18.0-beta.1")) {
+		if _, err := exec.LookPath("conntrack"); err != nil {
+			exit.Message(reason.GuestMissingConntrack, "Sorry, Kubernetes {{.k8sVersion}} requires conntrack to be installed in root's path", out.V{"k8sVersion": version.String()})
+		}
+	}
+}
+
 func exitIfNotForced(r reason.Kind, message string, v ...out.V) {
 	if !viper.GetBool(force) {
 		exit.Message(r, message, v...)

cmd/minikube/cmd/start_test.go

@@ -628,3 +628,40 @@ func TestValidatePorts(t *testing.T) {
 		})
 	}
 }
+
+func TestValidateSubnet(t *testing.T) {
+	type subnetTest struct {
+		subnet   string
+		errorMsg string
+	}
+	var tests = []subnetTest{
+		{
+			subnet:   "192.168.1.1",
+			errorMsg: "",
+		},
+		{
+			subnet:   "193.169.1.1",
+			errorMsg: "Sorry, the subnet 193.169.1.1 is not a private IP",
+		},
+		{
+			subnet:   "192.168.1.1/24",
+			errorMsg: "",
+		},
+		{
+			subnet:   "192.168.1.1/32",
+			errorMsg: "Sorry, the subnet provided does not have a mask less than or equal to /30",
+		},
+	}
+	for _, test := range tests {
+		t.Run(test.subnet, func(t *testing.T) {
+			gotError := ""
+			got := validateSubnet(test.subnet)
+			if got != nil {
+				gotError = got.Error()
+			}
+			if gotError != test.errorMsg {
+				t.Errorf("validateSubnet(subnet=%v): got %v, expected %v", test.subnet, got, test.errorMsg)
+			}
+		})
+	}
+}

pkg/network/network.go

@@ -126,12 +126,9 @@ func lookupInInterfaces(ip net.IP) (*Parameters, *net.IPNet, error) {
 var inspect = func(addr string) (*Parameters, error) {
 
 	// extract ip from addr
-	ip, network, err := net.ParseCIDR(addr)
+	ip, network, err := ParseAddr(addr)
 	if err != nil {
-		ip = net.ParseIP(addr)
-		if ip == nil {
-			return nil, fmt.Errorf("failed parsing address %s: %w", addr, err)
-		}
+		return nil, err
 	}
 
 	n := &Parameters{}
@@ -261,6 +258,19 @@ func FreeSubnet(startSubnet string, step, tries int) (*Parameters, error) {
 	return nil, fmt.Errorf("no free private network subnets found with given parameters (start: %q, step: %d, tries: %d)", startSubnet, step, tries)
 }
 
+// ParseAddr will try to parse an ip or a cidr address
+func ParseAddr(addr string) (net.IP, *net.IPNet, error) {
+	ip, network, err := net.ParseCIDR(addr)
+	if err != nil {
+		ip = net.ParseIP(addr)
+		if ip == nil {
+			return nil, nil, fmt.Errorf("failed parsing address %s: %w", addr, err)
+		}
+		err = nil
+	}
+	return ip, network, err
+}
+
 // reserveSubnet returns if subnet was successfully reserved for given period:
 //   - false, if it already has unexpired reservation
 //   - true, if new reservation was created or expired one renewed

pkg/network/network_test.go

@@ -114,3 +114,48 @@ func TestFreeSubnet(t *testing.T) {
 		}
 	})
 }
+
+func TestParseAddr(t *testing.T) {
+	t.Run("ValidIP", func(t *testing.T) {
+		addr := "192.168.9.0"
+		ip, _, err := ParseAddr(addr)
+		if err != nil {
+			t.Fatal(err)
+		}
+		if ip.String() != addr {
+			t.Errorf("expected IP = %q; got = %q", addr, ip.String())
+		}
+	})
+
+	t.Run("ValidCIDR", func(t *testing.T) {
+		addr := "192.168.9.0/30"
+		ip, cidr, err := ParseAddr(addr)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		expected := "192.168.9.0"
+		if ip.String() != expected {
+			t.Errorf("expected IP = %q; got = %q", expected, ip.String())
+		}
+
+		mask, _ := cidr.Mask.Size()
+		expectedMask := 30
+		if mask != expectedMask {
+			t.Errorf("expected mask = %q; got = %q", mask, expectedMask)
+		}
+	})
+
+	t.Run("InvalidAddr", func(t *testing.T) {
+		tests := []string{
+			"192.168.9",
+			"192.168.9.0/30000",
+		}
+		for _, test := range tests {
+			_, _, err := ParseAddr(test)
+			if err == nil {
+				t.Fatalf("expected to fail since address is invalid")
+			}
+		}
+	})
+}