fix(NRC): add IPv6 logic to bgp-local-addresses

pkg/controllers/routing/network_routes_controller.go

@@ -1099,13 +1099,40 @@ func (nrc *NetworkRoutingController) startBgpServer(grpcServer bool) error {
 
 	var localAddressList []string
 
-	if ipv4IsEnabled() {
-		localAddressList = append(localAddressList, nrc.localAddressList...)
+	if nrc.isIPv4Capable && !utils.ContainsIPv4Address(nrc.localAddressList) {
+		klog.Warningf("List of local addresses did not contain a valid IPv4 address, but IPv4 was " +
+			"enabled in kube-router's CLI options. BGP may not work as expected!")
 	}
 
-	if ipv6IsEnabled() {
-		ip := utils.FindBestIPv6NodeAddress(nrc.primaryIP, nrc.nodeIPv6Addrs)
-		localAddressList = append(localAddressList, ip.String())
+	if nrc.isIPv6Capable && !utils.ContainsIPv6Address(nrc.localAddressList) {
+		klog.Warningf("List of local addresses did not contain a valid IPv6 address, but IPv6 was " +
+			"enabled in kube-router's CLI options. BGP may not work as expected!")
+	}
+
+	for _, addr := range nrc.localAddressList {
+		ip := net.ParseIP(addr)
+		// This should have been caught in NewNetworkRoutingController, but we'll check once more just to be sure
+		if ip == nil {
+			klog.Warningf("was configured to listen on %s, but address was not valid, skipping (this should "+
+				"have been caught earlier in execution, please report upstream!)", addr)
+			continue
+		}
+
+		// Make sure that the address type matches what we're capable of before listening
+		if ip.To4() != nil {
+			if !nrc.isIPv4Capable {
+				klog.Warningf("was configured to listen on %s, but node is not enabled for IPv4 or does not "+
+					"have any IPv4 addresses configured for it, skipping", addr)
+				continue
+			}
+		} else {
+			if !nrc.isIPv6Capable {
+				klog.Warningf("was configured to listen on %s, but node is not enabled for IPv6 or does not "+
+					"have any IPv6 addresses configured for it, skipping", addr)
+				continue
+			}
+		}
+		localAddressList = append(localAddressList, addr)
 	}
 
 	global := &gobgpapi.Global{
@@ -1485,9 +1512,16 @@ func NewNetworkRoutingController(clientset kubernetes.Interface,
 
 	bgpLocalAddressListAnnotation, ok := node.ObjectMeta.Annotations[bgpLocalAddressAnnotation]
 	if !ok {
+		if nrc.isIPv4Capable {
+			nrc.localAddressList = append(nrc.localAddressList,
+				utils.FindBestIPv4NodeAddress(nrc.primaryIP, nrc.nodeIPv4Addrs).String())
+		}
+		if nrc.isIPv6Capable {
+			nrc.localAddressList = append(nrc.localAddressList,
+				utils.FindBestIPv6NodeAddress(nrc.primaryIP, nrc.nodeIPv6Addrs).String())
+		}
 		klog.Infof("Could not find annotation `kube-router.io/bgp-local-addresses` on node object so BGP "+
-			"will listen on node IP: %s address.", nrc.primaryIP.String())
-		nrc.localAddressList = append(nrc.localAddressList, nrc.primaryIP.String())
+			"will listen on node IP: %s addresses.", nrc.localAddressList)
 	} else {
 		klog.Infof("Found annotation `kube-router.io/bgp-local-addresses` on node object so BGP will listen "+
 			"on local IP's: %s", bgpLocalAddressListAnnotation)

pkg/controllers/routing/utils.go

@@ -85,33 +85,6 @@ func stringSliceB64Decode(s []string) ([]string, error) {
 	return ss, nil
 }
 
-func ipv4IsEnabled() bool {
-	l, err := net.Listen("tcp4", "")
-	if err != nil {
-		return false
-	}
-	_ = l.Close()
-
-	return true
-}
-
-func ipv6IsEnabled() bool {
-	// If ipv6 is disabled with;
-	//
-	//  sysctl -w net.ipv6.conf.all.disable_ipv6=1
-	//
-	// It is still possible to listen on the any-address "::". So this
-	// function tries the loopback address "::1" which must be present
-	// if ipv6 is enabled.
-	l, err := net.Listen("tcp6", "[::1]:0")
-	if err != nil {
-		return false
-	}
-	_ = l.Close()
-
-	return true
-}
-
 func getNodeSubnet(nodeIP net.IP) (net.IPNet, string, error) {
 	links, err := netlink.LinkList()
 	if err != nil {

pkg/utils/utils.go

@@ -2,6 +2,7 @@ package utils
 
 import (
 	"io"
+	"net"
 	"sync"
 )
 
@@ -43,3 +44,34 @@ func (b *Broadcaster) Notify(instance interface{}) {
 func CloseCloserDisregardError(handler io.Closer) {
 	_ = handler.Close()
 }
+
+// ContainsIPv4Address checks a given string array to see if it contains a valid IPv4 address within it
+func ContainsIPv4Address(addrs []string) bool {
+	for _, addr := range addrs {
+		ip := net.ParseIP(addr)
+		if ip == nil {
+			continue
+		}
+		if ip.To4() != nil {
+			return true
+		}
+	}
+	return false
+}
+
+// ContainsIPv6Address checks a given string array to see if it contains a valid IPv6 address within it
+func ContainsIPv6Address(addrs []string) bool {
+	for _, addr := range addrs {
+		ip := net.ParseIP(addr)
+		if ip == nil {
+			continue
+		}
+		if ip.To4() != nil {
+			continue
+		}
+		if ip.To16() != nil {
+			return true
+		}
+	}
+	return false
+}