Make iptables use semver lib

pkg/util/iptables/iptables.go

@@ -21,10 +21,10 @@ import (
 	"io/ioutil"
 	"os"
 	"regexp"
-	"strconv"
 	"strings"
 	"sync"
 
+	"github.com/coreos/go-semver/semver"
 	"github.com/golang/glog"
 	"k8s.io/kubernetes/pkg/util"
 	utilexec "k8s.io/kubernetes/pkg/util/exec"
@@ -106,6 +106,10 @@ type FlushFlag bool
 const FlushTables FlushFlag = true
 const NoFlushTables FlushFlag = false
 
+// Versions of iptables less than this do not support the -C / --check flag
+// (test whether a rule exists).
+const MinCheckVersion = "1.4.11"
+
 // runner implements Interface in terms of exec("iptables").
 type runner struct {
 	mu       sync.Mutex
@@ -399,44 +403,24 @@ func makeFullArgs(table Table, chain Chain, args ...string) []string {
 
 // Checks if iptables has the "-C" flag
 func getIptablesHasCheckCommand(exec utilexec.Interface) (bool, error) {
+	minVersion, err := semver.NewVersion(MinCheckVersion)
+	if err != nil {
+		return false, err
+	}
+	// Returns "vX.Y.Z".
 	vstring, err := GetIptablesVersionString(exec)
 	if err != nil {
 		return false, err
 	}
-
-	v1, v2, v3, err := extractIptablesVersion(vstring)
+	// Make a semver of the part after the v in "vX.X.X".
+	version, err := semver.NewVersion(vstring[1:])
 	if err != nil {
 		return false, err
 	}
-
-	return iptablesHasCheckCommand(v1, v2, v3), nil
-}
-
-// extractIptablesVersion returns the first three components of the iptables version.
-// e.g. "iptables v1.3.66" would return (1, 3, 66, nil)
-func extractIptablesVersion(str string) (int, int, int, error) {
-	versionMatcher := regexp.MustCompile("v([0-9]+)\\.([0-9]+)\\.([0-9]+)")
-	result := versionMatcher.FindStringSubmatch(str)
-	if result == nil {
-		return 0, 0, 0, fmt.Errorf("no iptables version found in string: %s", str)
+	if version.LessThan(*minVersion) {
+		return false, nil
 	}
-
-	v1, err := strconv.Atoi(result[1])
-	if err != nil {
-		return 0, 0, 0, err
-	}
-
-	v2, err := strconv.Atoi(result[2])
-	if err != nil {
-		return 0, 0, 0, err
-	}
-
-	v3, err := strconv.Atoi(result[3])
-	if err != nil {
-		return 0, 0, 0, err
-	}
-
-	return v1, v2, v3, nil
+	return true, nil
 }
 
 // GetIptablesVersionString runs "iptables --version" to get the version string,
@@ -455,17 +439,3 @@ func GetIptablesVersionString(exec utilexec.Interface) (string, error) {
 	}
 	return match[0], nil
 }
-
-// Checks if an iptables version is after 1.4.11, when --check was added
-func iptablesHasCheckCommand(v1 int, v2 int, v3 int) bool {
-	if v1 > 1 {
-		return true
-	}
-	if v1 == 1 && v2 > 4 {
-		return true
-	}
-	if v1 == 1 && v2 == 4 && v3 >= 11 {
-		return true
-	}
-	return false
-}