[!] add cross-platform support for ARP gratuitous requests, fixes #288 (#290)

Author: pashagolub

README.md

@@ -5,8 +5,8 @@ go 1.23.0
 toolchain go1.24.1
 
 require (
+	github.com/google/gopacket v1.1.19
 	github.com/hashicorp/consul/api v1.31.2
-	github.com/mdlayher/arp v0.0.0-20220512170110-6706a2966875
 	github.com/spf13/pflag v1.0.6
 	github.com/spf13/viper v1.20.0
 	go.etcd.io/etcd/client/v3 v3.5.19
@@ -31,12 +31,8 @@ require (
 	github.com/hashicorp/go-rootcerts v1.0.2 // indirect
 	github.com/hashicorp/golang-lru v1.0.2 // indirect
 	github.com/hashicorp/serf v0.10.1 // indirect
-	github.com/josharian/native v1.1.0 // indirect
 	github.com/mattn/go-colorable v0.1.13 // indirect
 	github.com/mattn/go-isatty v0.0.20 // indirect
-	github.com/mdlayher/ethernet v0.0.0-20220221185849-529eae5b6118 // indirect
-	github.com/mdlayher/packet v1.1.2 // indirect
-	github.com/mdlayher/socket v0.5.1 // indirect
 	github.com/mitchellh/go-homedir v1.1.0 // indirect
 	github.com/mitchellh/mapstructure v1.5.0 // indirect
 	github.com/niemeyer/pretty v0.0.0-20200227124842-a10e7caefd8e // indirect
@@ -51,7 +47,6 @@ require (
 	go.uber.org/multierr v1.11.0 // indirect
 	golang.org/x/exp v0.0.0-20250106191152-7588d65b2ba8 // indirect
 	golang.org/x/net v0.36.0 // indirect
-	golang.org/x/sync v0.11.0 // indirect
 	golang.org/x/text v0.22.0 // indirect
 	google.golang.org/genproto/googleapis/api v0.0.0-20241209162323-e6fa225c2576 // indirect
 	google.golang.org/genproto/googleapis/rpc v0.0.0-20241223144023-3abc09e42ca8 // indirect

go.mod

@@ -51,11 +51,11 @@ github.com/google/btree v1.0.1 h1:gK4Kx5IaGY9CD5sPJ36FHiBJ6ZXl0kilRiiCj+jdYp4=
 github.com/google/btree v1.0.1/go.mod h1:xXMiIv4Fb/0kKde4SpL7qlzvu5cMJDRkFDxJfI9uaxA=
 github.com/google/go-cmp v0.3.1/go.mod h1:8QqcDgzrUqlUb/G2PQTWiueGozuR1884gddMywk6iLU=
 github.com/google/go-cmp v0.4.0/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
-github.com/google/go-cmp v0.5.6/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
-github.com/google/go-cmp v0.5.7/go.mod h1:n+brtR0CgQNWTVd5ZUFpTBC8YFBDLK/h/bpaJ8/DtOE=
 github.com/google/go-cmp v0.6.0 h1:ofyhxvXcZhMsU5ulbFiLKl/XBFqE1GSq7atu8tAmTRI=
 github.com/google/go-cmp v0.6.0/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
 github.com/google/gofuzz v1.0.0/go.mod h1:dBl0BpW6vV/+mYPU4Po3pmUjxk6FQPldtuIdl/M65Eg=
+github.com/google/gopacket v1.1.19 h1:ves8RnFZPGiFnTS0uPQStjwru6uO6h+nlr9j6fL7kF8=
+github.com/google/gopacket v1.1.19/go.mod h1:iJ8V8n6KS+z2U1A8pUwu8bW5SyEMkXJB8Yo/Vo+TKTo=
 github.com/hashicorp/consul/api v1.31.2 h1:NicObVJHcCmyOIl7Z9iHPvvFrocgTYo9cITSGg0/7pw=
 github.com/hashicorp/consul/api v1.31.2/go.mod h1:Z8YgY0eVPukT/17ejW+l+C7zJmKwgPHtjU1q16v/Y40=
 github.com/hashicorp/consul/sdk v0.16.1 h1:V8TxTnImoPD5cj0U9Spl0TUxcytjcbbJeADFF07KdHg=
@@ -102,9 +102,6 @@ github.com/hashicorp/memberlist v0.5.0 h1:EtYPN8DpAURiapus508I4n9CzHs2W+8NZGbmmR
 github.com/hashicorp/memberlist v0.5.0/go.mod h1:yvyXLpo0QaGE59Y7hDTsTzDD25JYBZ4mHgHUZ8lrOI0=
 github.com/hashicorp/serf v0.10.1 h1:Z1H2J60yRKvfDYAOZLd2MU0ND4AH/WDz7xYHDWQsIPY=
 github.com/hashicorp/serf v0.10.1/go.mod h1:yL2t6BqATOLGc5HF7qbFkTfXoPIY0WZdWHfEvMqbG+4=
-github.com/josharian/native v1.0.0/go.mod h1:7X/raswPFr05uY3HiLlYeyQntB6OO7E/d2Cu7qoaN2w=
-github.com/josharian/native v1.1.0 h1:uuaP0hAbW7Y4l0ZRQ6C9zfb7Mg1mbFKry/xzDAfmtLA=
-github.com/josharian/native v1.1.0/go.mod h1:7X/raswPFr05uY3HiLlYeyQntB6OO7E/d2Cu7qoaN2w=
 github.com/json-iterator/go v1.1.6/go.mod h1:+SdeFBvtyEkXs7REEP0seUULqWtbJapLOCVDaaPEHmU=
 github.com/json-iterator/go v1.1.9/go.mod h1:KdQUCv79m/52Kvf8AW2vK1V8akMuk1QjK/uOdHXbAo4=
 github.com/julienschmidt/httprouter v1.2.0/go.mod h1:SYymIcj16QtmaHHD7aYtjjsJG7VTCxuUUipMqKk8s4w=
@@ -135,16 +132,6 @@ github.com/mattn/go-isatty v0.0.16/go.mod h1:kYGgaQfpe5nmfYZH+SKPsOc2e4SrIfOl2e/
 github.com/mattn/go-isatty v0.0.20 h1:xfD0iDuEKnDkl03q4limB+vH+GxLEtL/jb4xVJSWWEY=
 github.com/mattn/go-isatty v0.0.20/go.mod h1:W+V8PltTTMOvKvAeJH7IuucS94S2C6jfK/D7dTCTo3Y=
 github.com/matttproud/golang_protobuf_extensions v1.0.1/go.mod h1:D8He9yQNgCq6Z5Ld7szi9bcBfOoFv/3dc6xSMkL2PC0=
-github.com/mdlayher/arp v0.0.0-20220512170110-6706a2966875 h1:ql8x//rJsHMjS+qqEag8n3i4azw1QneKh5PieH9UEbY=
-github.com/mdlayher/arp v0.0.0-20220512170110-6706a2966875/go.mod h1:kfOoFJuHWp76v1RgZCb9/gVUc7XdY877S2uVYbNliGc=
-github.com/mdlayher/ethernet v0.0.0-20220221185849-529eae5b6118 h1:2oDp6OOhLxQ9JBoUuysVz9UZ9uI6oLUbvAZu0x8o+vE=
-github.com/mdlayher/ethernet v0.0.0-20220221185849-529eae5b6118/go.mod h1:ZFUnHIVchZ9lJoWoEGUg8Q3M4U8aNNWA3CVSUTkW4og=
-github.com/mdlayher/packet v1.0.0/go.mod h1:eE7/ctqDhoiRhQ44ko5JZU2zxB88g+JH/6jmnjzPjOU=
-github.com/mdlayher/packet v1.1.2 h1:3Up1NG6LZrsgDVn6X4L9Ge/iyRyxFEFD9o6Pr3Q1nQY=
-github.com/mdlayher/packet v1.1.2/go.mod h1:GEu1+n9sG5VtiRE4SydOmX5GTwyyYlteZiFU+x0kew4=
-github.com/mdlayher/socket v0.2.1/go.mod h1:QLlNPkFR88mRUNQIzRBMfXxwKal8H7u1h3bL1CV+f0E=
-github.com/mdlayher/socket v0.5.1 h1:VZaqt6RkGkt2OE9l3GcC6nZkqD3xKeQLyfleW/uBcos=
-github.com/mdlayher/socket v0.5.1/go.mod h1:TjPLHI1UgwEv5J1B5q0zTZq12A/6H7nKmtTanQE37IQ=
 github.com/miekg/dns v1.1.26/go.mod h1:bPDLeHnStXmXAq1m/Ch/hvfNHr14JKNPMBo3VZKjuso=
 github.com/miekg/dns v1.1.41 h1:WMszZWJG0XmzbK9FEmzH2TVcqYzFesusSIB41b8KHxY=
 github.com/miekg/dns v1.1.41/go.mod h1:p6aan82bvRIyn+zDIv9xYNUpwa73JcSh9BKwknJysuI=
@@ -239,12 +226,12 @@ golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550/go.mod h1:yigFU9vqHzYiE8U
 golang.org/x/crypto v0.0.0-20200622213623-75b288015ac9/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
 golang.org/x/exp v0.0.0-20250106191152-7588d65b2ba8 h1:yqrTHse8TCMW1M1ZCP+VAR/l0kKxwaAIqN/il7x4voA=
 golang.org/x/exp v0.0.0-20250106191152-7588d65b2ba8/go.mod h1:tujkw807nyEEAamNbDrEGzRav+ilXA7PCRAd6xsmwiU=
+golang.org/x/lint v0.0.0-20200302205851-738671d3881b/go.mod h1:3xt1FjdF8hUf6vQPIChWIBhFzV8gjjsPE/fR3IyQdNY=
+golang.org/x/mod v0.1.1-0.20191105210325-c90efee705ee/go.mod h1:QqPTAvyqsEbceGzBzNggFXnrqF1CaUcvgkdR5Ot7KZg=
 golang.org/x/mod v0.2.0/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
 golang.org/x/mod v0.3.0/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
 golang.org/x/net v0.0.0-20181114220301-adae6a3d119a/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
 golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
-golang.org/x/net v0.0.0-20190503192946-f4e77d36d62c/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
-golang.org/x/net v0.0.0-20190603091049-60506f45cf65/go.mod h1:HSz+uSET+XFnRR8LxR5pz3Of3rY3CfYBVs4xY44aLks=
 golang.org/x/net v0.0.0-20190613194153-d28f0bde5980/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
 golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
 golang.org/x/net v0.0.0-20190923162816-aa69164e4478/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
@@ -260,8 +247,6 @@ golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJ
 golang.org/x/sync v0.0.0-20190911185100-cd5d95a43a6e/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.0.0-20201020160332-67f06af15bc9/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.0.0-20210220032951-036812b2e83c/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
-golang.org/x/sync v0.11.0 h1:GGz8+XQP4FvTTrjZPzNKTMFtSXH80RAzG+5ghFPgK9w=
-golang.org/x/sync v0.11.0/go.mod h1:Czt+wKu1gCyEFDUtn0jG5QVvpJ6rzVqr5aXyt9drQfk=
 golang.org/x/sys v0.0.0-20180823144017-11551d06cbcc/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20180905080454-ebe1bf3edb33/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20181116152217-5ac8a444bdc5/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
@@ -281,7 +266,6 @@ golang.org/x/sys v0.0.0-20210303074136-134d130e1a04/go.mod h1:h1NjWce9XRLGQEsW7w
 golang.org/x/sys v0.0.0-20210330210617-4fbd30eecc44/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20210630005230-0f9fa26af87c/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20210927094055-39ccf1dd6fa6/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/sys v0.0.0-20220209214540-3681064d5158/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20220503163025-988cb79eb6c6/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20220728004956-3c1f35247d10/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20220811171246-fbc7d0a398ab/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
@@ -298,6 +282,7 @@ golang.org/x/text v0.22.0/go.mod h1:YRoo4H8PVmsu+E3Ou7cqLVH8oXWIHVoX0jqUWALQhfY=
 golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
 golang.org/x/tools v0.0.0-20190907020128-2ca718005c18/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
 golang.org/x/tools v0.0.0-20191119224855-298f0cb1881e/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
+golang.org/x/tools v0.0.0-20200130002326-2f3ba24bd6e7/go.mod h1:TB2adYChydJhpapKDTa4BR/hXlZSLoq2Wpct/0txZ28=
 golang.org/x/tools v0.0.0-20200619180055-7c47624df98f/go.mod h1:EkVYQZoAsY45+roYkvgYkIh4xh/qjgUK9TdY2XT94GE=
 golang.org/x/tools v0.0.0-20210106214847-113979e3529a/go.mod h1:emZCQorbCU4vsT4fOWvOPXz4eW1wZW4PmDk9uLelYpA=
 golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=

go.sum

@@ -5,7 +5,8 @@ import (
 	"net"
 	"strings"
 
-	arp "github.com/mdlayher/arp"
+	"github.com/google/gopacket"
+	"github.com/google/gopacket/layers"
 )
 
 // BasicConfigurer can be used to enable vip-management on nodes
@@ -16,7 +17,6 @@ import (
 // nearby routers and other devices.
 type BasicConfigurer struct {
 	*IPConfiguration
-	arpClient  *arp.Client
 	ntecontext uint32 //used by Windows to delete IP address
 }
 
@@ -48,8 +48,43 @@ func (c *BasicConfigurer) queryAddress() bool {
 	return false
 }
 
-func (c *BasicConfigurer) cleanupArp() {
-	if c.arpClient != nil {
-		c.arpClient.Close()
+const (
+	MACAddressSize  = 6
+	IPv4AddressSize = 4
+)
+
+// createGratuitousARP prepares a packet with a gratuitous ARP request
+func (c *BasicConfigurer) createGratuitousARP() ([]byte, error) {
+	// Create the Ethernet layer
+	ethLayer := &layers.Ethernet{
+		SrcMAC:       c.Iface.HardwareAddr,
+		DstMAC:       net.HardwareAddr{0xff, 0xff, 0xff, 0xff, 0xff, 0xff}, // Broadcast
+		EthernetType: layers.EthernetTypeARP,
 	}
+
+	// Create the ARP layer
+	arpLayer := &layers.ARP{
+		AddrType:          layers.LinkTypeEthernet,
+		Protocol:          layers.EthernetTypeIPv4,
+		HwAddressSize:     MACAddressSize,
+		ProtAddressSize:   IPv4AddressSize,
+		Operation:         layers.ARPReply, // Gratuitous ARP is sent as a reply
+		SourceHwAddress:   c.Iface.HardwareAddr,
+		SourceProtAddress: c.IPConfiguration.VIP.AsSlice(),
+		DstHwAddress:      c.Iface.HardwareAddr, // Gratuitous ARP targets itself
+		DstProtAddress:    c.IPConfiguration.VIP.AsSlice(),
+	}
+
+	// Create a packet with the layers
+	buffer := gopacket.NewSerializeBuffer()
+	opts := gopacket.SerializeOptions{
+		FixLengths:       true,
+		ComputeChecksums: true,
+	}
+
+	if err := gopacket.SerializeLayers(buffer, opts, ethLayer, arpLayer); err != nil {
+		return nil, err
+	}
+
+	return buffer.Bytes(), nil
 }

ipmanager/basicConfigurer.go

@@ -3,37 +3,46 @@ package ipmanager
 import (
 	"net"
 	"os/exec"
-	"time"
-
-	arp "github.com/mdlayher/arp"
+	"syscall"
 )
 
-const (
-	arpRequestOp = 1
-	arpReplyOp   = 2
-)
+// htons converts uint16 to network byte order
+func htons(i uint16) uint16 {
+	return (i<<8)&0xff00 | i>>8
+}
 
-var (
-	ethernetBroadcast = net.HardwareAddr{0xff, 0xff, 0xff, 0xff, 0xff, 0xff}
-)
+func sendPacketLinux(iface net.Interface, packetData []byte) error {
+	fd, err := syscall.Socket(syscall.AF_PACKET, syscall.SOCK_RAW, int(htons(syscall.ETH_P_ALL)))
+	if err != nil {
+		return err
+	}
+	defer syscall.Close(fd)
 
-// configureAddress assigns virtual IP address
-func (c *BasicConfigurer) configureAddress() bool {
-	if c.arpClient == nil {
-		if err := c.createArpClient(); err != nil {
-			log.Error("Couldn't create an Arp client:", err)
-		}
+	var sll syscall.SockaddrLinklayer
+	sll.Protocol = htons(syscall.ETH_P_ARP)
+	sll.Ifindex = iface.Index
+	sll.Hatype = syscall.ARPHRD_ETHER
+	sll.Pkttype = syscall.PACKET_BROADCAST
+
+	if err = syscall.Bind(fd, &sll); err != nil {
+		return err
 	}
 
-	log.Infof("Configuring address %s on %s", c.getCIDR(), c.Iface.Name)
+	return syscall.Sendto(fd, packetData, 0, &sll)
+}
 
+// configureAddress assigns virtual IP address
+func (c *BasicConfigurer) configureAddress() bool {
+	log.Infof("Configuring address %s on %s", c.getCIDR(), c.Iface.Name)
 	result := c.runAddressConfiguration("add")
-
 	if result {
-		// For now it is save to say that also working even if a
-		// gratuitous arp message could not be send but logging an
-		// errror should be enough.
-		_ = c.arpSendGratuitous()
+		if buff, err := c.createGratuitousARP(); err != nil {
+			log.Warn("Failed to compose gratuitous ARP request: ", err)
+		} else {
+			if err := sendPacketLinux(c.Iface, buff); err != nil {
+				log.Warn("Failed to send gratuitous ARP request: ", err)
+			}
+		}
 	}
 
 	return result
@@ -64,96 +73,3 @@ func (c *BasicConfigurer) runAddressConfiguration(action string) bool {
 	}
 	return true
 }
-
-func (c *BasicConfigurer) createArpClient() (err error) {
-	for i := 0; i < c.RetryNum; i++ {
-		if c.arpClient, err = arp.Dial(&c.Iface); err == nil {
-			return
-		}
-		log.Infof("Problems with producing the arp client: %s", err)
-		time.Sleep(time.Duration(c.RetryAfter) * time.Millisecond)
-	}
-	return
-}
-
-// sends a gratuitous ARP request and reply
-func (c *BasicConfigurer) arpSendGratuitous() error {
-	/* While RFC 2002 does not say whether a gratuitous ARP request or reply is preferred
-	 * to update ones neighbours' MAC tables, the Wireshark Wiki recommends sending both.
-	 *		https://wiki.wireshark.org/Gratuitous_ARP
-	 * This site also recommends sending a reply, as requests might be ignored by some hardware:
-	 *		https://support.citrix.com/article/CTX112701
-	 */
-	if c.arpClient == nil {
-		log.Info("No arp client available, skip send gratuitous ARP")
-		return nil
-	}
-	gratuitousReplyPackage, err := arp.NewPacket(
-		arpReplyOp,
-		c.Iface.HardwareAddr,
-		c.VIP,
-		c.Iface.HardwareAddr,
-		c.VIP,
-	)
-	if err != nil {
-		log.Infof("Gratuitous arp reply package is malformed: %s", err)
-		return err
-	}
-
-	/* RFC 2002 specifies (in section 4.6) that a gratuitous ARP request
-	 * should "not set" the target Hardware Address (THA).
-	 * Since the arp package offers no option to leave the THA out, we specify the Zero-MAC.
-	 * If parsing that fails for some reason, we'll just use the local interface's address.
-	 * The field is probably ignored by the receivers' implementation anyway.
-	 */
-	arpRequestDestMac, err := net.ParseMAC("00:00:00:00:00:00")
-	if err != nil {
-		// not entirely RFC-2002 conform but better then nothing.
-		arpRequestDestMac = c.Iface.HardwareAddr
-	}
-
-	gratuitousRequestPackage, err := arp.NewPacket(
-		arpRequestOp,
-		c.Iface.HardwareAddr,
-		c.VIP,
-		arpRequestDestMac,
-		c.VIP,
-	)
-	if err != nil {
-		log.Infof("Gratuitous arp request package is malformed: %s", err)
-		return err
-	}
-
-	for i := 0; i < c.RetryNum; i++ {
-		errReply := c.arpClient.WriteTo(gratuitousReplyPackage, ethernetBroadcast)
-		if err != nil {
-			log.Error("Couldn't write to the arpClient:", errReply)
-		} else {
-			log.Info("Sent gratuitous ARP reply")
-		}
-
-		errRequest := c.arpClient.WriteTo(gratuitousRequestPackage, ethernetBroadcast)
-		if err != nil {
-			log.Error("Couldn't write to the arpClient:", errRequest)
-		} else {
-			log.Info("Sent gratuitous ARP request")
-		}
-
-		if errReply != nil || errRequest != nil {
-			/* If something went wrong while sending the packages, we'll recreate the ARP client for the next try,
-			 * to avoid having a stale client that gives "network is down" error.
-			 */
-			err = c.createArpClient()
-		} else {
-			//TODO: think about whether to leave this out to achieve simple repeat sending of GARP packages
-			break
-		}
-		time.Sleep(time.Duration(c.RetryAfter) * time.Millisecond)
-	}
-	if err != nil {
-		log.Error("Too many retries", err)
-		return err
-	}
-
-	return nil
-}

ipmanager/basicConfigurer_linux.go

@@ -7,6 +7,18 @@ import (
 	"github.com/cybertec-postgresql/vip-manager/iphlpapi"
 )
 
+func sendPacketWindows(iface net.Interface, packetData []byte) error {
+	// Open a raw socket using Winsock
+	conn, err := net.Dial("ip4:ethernet", iface.HardwareAddr.String())
+	if err != nil {
+		return err
+	}
+	defer conn.Close()
+	// Send the packet
+	_, err = conn.Write(packetData)
+	return err
+}
+
 // configureAddress assigns virtual IP address
 func (c *BasicConfigurer) configureAddress() bool {
 	log.Infof("Configuring address %s on %s", c.getCIDR(), c.Iface.Name)
@@ -25,10 +37,14 @@ func (c *BasicConfigurer) configureAddress() bool {
 		log.Error("Failed to add address: ", err)
 		return false
 	}
-	// For now it is save to say that also working even if a
-	// gratuitous arp message could not be send but logging an
-	// errror should be enough.
-	//_ = c.ARPSendGratuitous()
+
+	if buff, err := c.createGratuitousARP(); err != nil {
+		log.Warn("Failed to compose gratuitous ARP request: ", err)
+	} else {
+		if err := sendPacketWindows(c.Iface, buff); err != nil {
+			log.Warn("Failed to send gratuitous ARP request: ", err)
+		}
+	}
 	return true
 }
 

ipmanager/basicConfigurer_windows.go

@@ -275,8 +275,3 @@ func (c *HetznerConfigurer) runAddressConfiguration() bool {
 	c.cachedState = unknown
 	return false
 }
-
-func (c *HetznerConfigurer) cleanupArp() {
-	// dummy function as the usage of interfaces requires us to have this function.
-	// It is sufficient for the leader to tell Hetzner to switch the IP, no cleanup needed.
-}