Fix that Antrea Agent may crash when dualstack

When a Cluster is dualstack, it assumes that every Node is configured with
both IPv4 and IPv6 addresses for Antrea Agent. However, if a Node is only
configured with either IPv4 or IPv6 address, Antrea Agent will get crashed.

Signed-off-by: Hongliang Liu <lhongliang@vmware.com>

pkg/agent/openflow/pod_connectivity.go

@@ -75,15 +75,19 @@ func newFeaturePodConnectivity(
 		if ipProtocol == binding.ProtocolIP {
 			ctZones[ipProtocol] = CtZone
 			gatewayIPs[ipProtocol] = nodeConfig.GatewayConfig.IPv4
-			nodeIPs[ipProtocol] = nodeConfig.NodeIPv4Addr.IP
+			if nodeConfig.NodeIPv4Addr != nil {
+				nodeIPs[ipProtocol] = nodeConfig.NodeIPv4Addr.IP
+			}
 			if nodeConfig.PodIPv4CIDR != nil {
 				localCIDRs[ipProtocol] = *nodeConfig.PodIPv4CIDR
 			}
 			ipCtZoneTypeRegMarks[ipProtocol] = IPCtZoneTypeRegMark
 		} else if ipProtocol == binding.ProtocolIPv6 {
 			ctZones[ipProtocol] = CtZoneV6
 			gatewayIPs[ipProtocol] = nodeConfig.GatewayConfig.IPv6
-			nodeIPs[ipProtocol] = nodeConfig.NodeIPv6Addr.IP
+			if nodeConfig.NodeIPv6Addr != nil {
+				nodeIPs[ipProtocol] = nodeConfig.NodeIPv6Addr.IP
+			}
 			if nodeConfig.PodIPv6CIDR != nil {
 				localCIDRs[ipProtocol] = *nodeConfig.PodIPv6CIDR
 			}