Ensure kernel sends GARPs to avoid communication failures (#4649)

Signed-off-by: Cyclinder Kuo <[email protected]>

cmd/spiderpool/cmd/command_add.go

@@ -25,6 +25,7 @@ import (
 	"github.com/spidernet-io/spiderpool/api/v1/agent/models"
 	"github.com/spidernet-io/spiderpool/pkg/constant"
 	spiderpoolip "github.com/spidernet-io/spiderpool/pkg/ip"
+	"github.com/spidernet-io/spiderpool/pkg/networking/networking"
 	"github.com/spidernet-io/spiderpool/pkg/openapi"
 )
 
@@ -164,8 +165,7 @@ func CmdAdd(args *skel.CmdArgs) (err error) {
 	// do ip conflict and gateway detection
 	logger.Sugar().Info("postIpam response",
 		zap.Any("DNS", ipamResponse.Payload.DNS),
-		zap.Any("Routes", ipamResponse.Payload.Routes),
-		zap.Any("Ips", ipamResponse.Payload.Ips))
+		zap.Any("Routes", ipamResponse.Payload.Routes))
 
 	if err = DetectIPConflictAndGatewayReachable(logger, args.IfName, hostNs, netns, ipamResponse.Payload.Ips); err != nil {
 		if errors.Is(err, constant.ErrIPConflict) || errors.Is(err, constant.ErrGatewayUnreachable) {
@@ -179,6 +179,30 @@ func CmdAdd(args *skel.CmdArgs) (err error) {
 		return err
 	}
 
+	// CNI will set the interface to up, and the kernel only sends GARPs/Unsolicited NA when the interface
+	// goes from down to up or when the link-layer address changes on the interfaces. in order to the
+	// kernel send GARPs/Unsolicited NA when the interface goes from down to up.
+	// see https://github.com/spidernet-io/spiderpool/issues/4650
+	var ipRes []net.IP
+	for _, i := range ipamResponse.Payload.Ips {
+		if i.Address != nil && *i.Address != "" {
+			ipa, _, err := net.ParseCIDR(*i.Address)
+			if err != nil {
+				logger.Error(err.Error())
+				continue
+			}
+			ipRes = append(ipRes, ipa)
+		}
+	}
+
+	err = netns.Do(func(netNS ns.NetNS) error {
+		return networking.AnnounceIPs(logger, args.IfName, ipRes)
+	})
+
+	if err != nil {
+		logger.Error(err.Error())
+	}
+
 	// Assemble the result of IPAM request response.
 	result, err := assembleResult(conf.CNIVersion, args.IfName, ipamResponse)
 	if err != nil {

pkg/networking/networking/packet.go

@@ -18,6 +18,7 @@ import (
 	"syscall"
 	"time"
 
+	"go.uber.org/zap"
 	"golang.org/x/net/icmp"
 	"golang.org/x/net/ipv6"
 	"golang.org/x/sys/unix"
@@ -313,3 +314,39 @@ func ParseIPv6NeighborAdvertisementMsg(n int, buf []byte) (srcIP net.IP, mac net
 	}
 	return
 }
+
+func AnnounceIPs(logger *zap.Logger, iface string, ips []net.IP) error {
+	l, err := netlink.LinkByName(iface)
+	if err != nil {
+		return err
+	}
+
+	for _, addr := range ips {
+		logger.Debug("announcing ip", zap.String("ip", addr.String()), zap.String("interface", iface))
+		if addr.To4() != nil {
+			// send an gratuitous arp to announce the new mac address
+			if err = SendARPReuqest(l, addr, addr); err != nil {
+				logger.Error("failed to send gratuitous arps", zap.Error(err))
+			} else {
+				logger.Info("Send gratuitous arps successfully", zap.String("interface", iface))
+			}
+		} else {
+			ifi, err := net.InterfaceByName(iface)
+			if err != nil {
+				return fmt.Errorf("failed to InterfaceByName %s: %w", iface, err)
+			}
+
+			ndpClient, _, err := ndp.Listen(ifi, ndp.LinkLocal)
+			if err != nil {
+				return fmt.Errorf("failed to init ndp client: %w", err)
+			}
+			defer ndpClient.Close()
+			if err = SendUnsolicitedNeighborAdvertisement(addr, ifi, ndpClient); err != nil {
+				logger.Error("failed to send unsolicited neighbor advertisements", zap.Error(err))
+			} else {
+				logger.Info("Send unsolicited neighbor advertisements successfully", zap.String("interface", iface))
+			}
+		}
+	}
+	return nil
+}