fix encap ip when the tunnel interface has multiple addresses (#2340)

pkg/daemon/config.go

@@ -201,6 +201,10 @@ func (config *Configuration) initNicConfig(nicBridgeMappings map[string]string)
 			klog.Errorf("failed to find iface %s, %v", tunnelNic, err)
 			return err
 		}
+		srcIPs, err := getSrcIPsByRoutes(iface)
+		if err != nil {
+			return fmt.Errorf("failed to get src IPs by routes on interface %s: %v", iface.Name, err)
+		}
 		addrs, err := iface.Addrs()
 		if err != nil {
 			return fmt.Errorf("failed to get iface addr. %v", err)
@@ -210,14 +214,16 @@ func (config *Configuration) initNicConfig(nicBridgeMappings map[string]string)
 			if ip := net.ParseIP(ipStr); ip == nil || ip.IsLinkLocalUnicast() {
 				continue
 			}
-			encapIP = ipStr
-			break
+			if len(srcIPs) == 0 || util.ContainsString(srcIPs, ipStr) {
+				encapIP = ipStr
+				break
+			}
 		}
 		if len(encapIP) == 0 {
 			return fmt.Errorf("iface %s has no valid IP address", tunnelNic)
 		}
 
-		klog.Infof("use %s as tunnel interface", iface.Name)
+		klog.Infof("use %s on %s as tunnel address", encapIP, iface.Name)
 		mtu = iface.MTU
 		config.tunnelIface = iface.Name
 	}

pkg/daemon/config_linux.go

@@ -10,6 +10,25 @@ import (
 
 const defaultBindSocket = "/run/openvswitch/kube-ovn-daemon.sock"
 
+func getSrcIPsByRoutes(iface *net.Interface) ([]string, error) {
+	link, err := netlink.LinkByName(iface.Name)
+	if err != nil {
+		return nil, fmt.Errorf("failed to get link %s: %v", iface.Name, err)
+	}
+	routes, err := netlink.RouteList(link, netlink.FAMILY_ALL)
+	if err != nil {
+		return nil, fmt.Errorf("failed to get routes on link %s: %v", iface.Name, err)
+	}
+
+	srcIPs := make([]string, 0, 2)
+	for _, r := range routes {
+		if r.Src != nil && r.Scope == netlink.SCOPE_LINK {
+			srcIPs = append(srcIPs, r.Src.String())
+		}
+	}
+	return srcIPs, nil
+}
+
 func getIfaceByIP(ip string) (string, int, error) {
 	links, err := netlink.LinkList()
 	if err != nil {

pkg/daemon/config_windows.go

@@ -3,6 +3,7 @@ package daemon
 import (
 	"context"
 	"fmt"
+	"net"
 	"strings"
 
 	"github.com/Microsoft/hcsshim"
@@ -16,6 +17,11 @@ import (
 
 const defaultBindSocket = util.WindowsListenPipe
 
+func getSrcIPsByRoutes(iface *net.Interface) ([]string, error) {
+	// to be implemented in the future
+	return nil, nil
+}
+
 func getIfaceByIP(ip string) (string, int, error) {
 	iface, err := util.GetInterfaceByIP(ip)
 	if err != nil {