From 3b274e25defe4864f88b49ed00e3483cdfff17be Mon Sep 17 00:00:00 2001
From: Ferenc Toth <ferenc.2.toth@nokia.com>
Date: Tue, 16 Nov 2021 14:20:56 +0100
Subject: [PATCH] Send Gratuitous ARP after IPs are set

---
 plugins/main/ipvlan/ipvlan.go | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/plugins/main/ipvlan/ipvlan.go b/plugins/main/ipvlan/ipvlan.go
index 417a850d5..06b5117d4 100644
--- a/plugins/main/ipvlan/ipvlan.go
+++ b/plugins/main/ipvlan/ipvlan.go
@@ -18,8 +18,10 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
+	"net"
 	"runtime"
 
+	"github.com/j-keck/arping"
 	"github.com/vishvananda/netlink"
 
 	"github.com/containernetworking/cni/pkg/skel"
@@ -254,7 +256,21 @@ func cmdAdd(args *skel.CmdArgs) error {
 	result.Interfaces = []*current.Interface{ipvlanInterface}
 
 	err = netns.Do(func(_ ns.NetNS) error {
-		return ipam.ConfigureIface(args.IfName, result)
+		if err := ipam.ConfigureIface(args.IfName, result); err != nil {
+			return err
+		}
+
+		contVeth, err := net.InterfaceByName(args.IfName)
+		if err != nil {
+			return fmt.Errorf("failed to look up %q: %v", args.IfName, err)
+		}
+
+		for _, ipc := range result.IPs {
+			if ipc.Address.IP.To4() != nil {
+				_ = arping.GratuitousArpOverIface(ipc.Address.IP, *contVeth)
+			}
+		}
+		return nil
 	})
 	if err != nil {
 		return err