Merge pull request #4865 from sub-mod/proxier_go_change

use ChooseHostInterface in kube-proxy

pkg/util/util.go

@@ -17,9 +17,14 @@ limitations under the License.
 package util
 
 import (
+	"bufio"
+	"encoding/hex"
 	"encoding/json"
 	"fmt"
+	"io"
 	"io/ioutil"
+	"net"
+	"os"
 	"path"
 	"reflect"
 	"regexp"
@@ -252,3 +257,188 @@ func SplitQualifiedName(str string) (string, string) {
 func JoinQualifiedName(namespace, name string) string {
 	return path.Join(namespace, name)
 }
+
+type Route struct {
+	Interface   string
+	Destination net.IP
+	Gateway     net.IP
+	// TODO: add more fields here if needed
+}
+
+func getRoutes(input io.Reader) ([]Route, error) {
+	routes := []Route{}
+	if input == nil {
+		return nil, fmt.Errorf("input is nil")
+	}
+	scanner := bufio.NewReader(input)
+	for {
+		line, err := scanner.ReadString('\n')
+		if err == io.EOF {
+			break
+		}
+		//ignore the headers in the route info
+		if strings.HasPrefix(line, "Iface") {
+			continue
+		}
+		fields := strings.Fields(line)
+		routes = append(routes, Route{})
+		route := &routes[len(routes)-1]
+		route.Interface = fields[0]
+		ip, err := parseIP(fields[1])
+		if err != nil {
+			return nil, err
+		}
+		route.Destination = ip
+		ip, err = parseIP(fields[2])
+		if err != nil {
+			return nil, err
+		}
+		route.Gateway = ip
+	}
+	return routes, nil
+}
+
+func parseIP(str string) (net.IP, error) {
+	if str == "" {
+		return nil, fmt.Errorf("input is nil")
+	}
+	bytes, err := hex.DecodeString(str)
+	if err != nil {
+		return nil, err
+	}
+	//TODO add ipv6 support
+	if len(bytes) != net.IPv4len {
+		return nil, fmt.Errorf("only IPv4 is supported")
+	}
+	bytes[0], bytes[1], bytes[2], bytes[3] = bytes[3], bytes[2], bytes[1], bytes[0]
+	return net.IP(bytes), nil
+}
+
+func isInterfaceUp(intf *net.Interface) bool {
+	if intf == nil {
+		return false
+	}
+	if intf.Flags&net.FlagUp != 0 {
+		glog.V(4).Infof("Interface %v is up", intf.Name)
+		return true
+	}
+	return false
+}
+
+//getFinalIP method receives all the IP addrs of a Interface
+//and returns a nil if the address is Loopback , Ipv6  or nil.
+//It returns a valid IPv4 if an Ipv4 address is found in the array.
+func getFinalIP(addrs []net.Addr) (net.IP, error) {
+	if len(addrs) > 0 {
+		for i := range addrs {
+			glog.V(4).Infof("Checking addr  %s.", addrs[i].String())
+			ip, _, err := net.ParseCIDR(addrs[i].String())
+			if err != nil {
+				return nil, err
+			}
+			//Only IPv4
+			//TODO : add IPv6 support
+			if ip.To4() != nil {
+				if !ip.IsLoopback() {
+					glog.V(4).Infof("IP found %v", ip)
+					return ip, nil
+				} else {
+					glog.V(4).Infof("Loopback found %v", ip)
+				}
+			} else {
+				glog.V(4).Infof("%v is not a valid IPv4 address", ip)
+			}
+
+		}
+	}
+	return nil, nil
+}
+
+func getIPFromInterface(intfName string, nw networkInterfacer) (net.IP, error) {
+	intf, err := nw.InterfaceByName(intfName)
+	if err != nil {
+		return nil, err
+	}
+	if isInterfaceUp(intf) {
+		addrs, err := nw.Addrs(intf)
+		if err != nil {
+			return nil, err
+		}
+		glog.V(4).Infof("Interface %q has %d addresses :%v.", intfName, len(addrs), addrs)
+		finalIP, err := getFinalIP(addrs)
+		if err != nil {
+			return nil, err
+		}
+		if finalIP != nil {
+			glog.V(4).Infof("valid IPv4 address for interface %q found as %v.", intfName, finalIP)
+			return finalIP, nil
+		}
+	}
+
+	return nil, nil
+}
+
+//ChooseHostInterface is a method used fetch an IP for a daemon.
+//It uses data from /proc/net/route file.
+//For a node with no internet connection ,it returns error
+//For a multi n/w interface node it returns the IP of the interface with gateway on it.
+func ChooseHostInterface() (net.IP, error) {
+	inFile, err := os.Open("/proc/net/route")
+	if err != nil {
+		return nil, err
+	}
+	defer inFile.Close()
+	var nw networkInterfacer = networkInterface{}
+	return chooseHostInterfaceFromRoute(inFile, nw)
+}
+
+type networkInterfacer interface {
+	InterfaceByName(intfName string) (*net.Interface, error)
+	Addrs(intf *net.Interface) ([]net.Addr, error)
+}
+
+type networkInterface struct{}
+
+func (_ networkInterface) InterfaceByName(intfName string) (*net.Interface, error) {
+	intf, err := net.InterfaceByName(intfName)
+	if err != nil {
+		return nil, err
+	}
+	return intf, nil
+}
+
+func (_ networkInterface) Addrs(intf *net.Interface) ([]net.Addr, error) {
+	addrs, err := intf.Addrs()
+	if err != nil {
+		return nil, err
+	}
+	return addrs, nil
+}
+
+func chooseHostInterfaceFromRoute(inFile io.Reader, nw networkInterfacer) (net.IP, error) {
+	routes, err := getRoutes(inFile)
+	if err != nil {
+		return nil, err
+	}
+	zero := net.IP{0, 0, 0, 0}
+	var finalIP net.IP
+	for i := range routes {
+		//find interface with gateway
+		if routes[i].Destination.Equal(zero) {
+			glog.V(4).Infof("Default route transits interface %q", routes[i].Interface)
+			finalIP, err := getIPFromInterface(routes[i].Interface, nw)
+			if err != nil {
+				return nil, err
+			}
+			if finalIP != nil {
+				glog.V(4).Infof("Choosing IP %v ", finalIP)
+				return finalIP, nil
+			}
+		}
+	}
+	glog.V(4).Infof("No valid IP found")
+	if finalIP == nil {
+		return nil, fmt.Errorf("Unable to select an IP.")
+	}
+	return nil, nil
+}