replace pcap with raw socket calls

Author: pashagolub

ipmanager/basicConfigurer.go

@@ -7,7 +7,6 @@ import (
 
 	"github.com/google/gopacket"
 	"github.com/google/gopacket/layers"
-	"github.com/google/gopacket/pcap"
 )
 
 // BasicConfigurer can be used to enable vip-management on nodes
@@ -55,14 +54,7 @@ const (
 )
 
 // arpSendGratuitous is a function that sends gratuitous ARP requests
-func (c *BasicConfigurer) arpSendGratuitous() error {
-	// Open the network interface for sending
-	handle, err := pcap.OpenLive(c.Iface.Name, 65536, false, pcap.BlockForever)
-	if err != nil {
-		return err
-	}
-	defer handle.Close()
-
+func (c *BasicConfigurer) createGratuitousARP() ([]byte, error) {
 	// Create the Ethernet layer
 	ethLayer := &layers.Ethernet{
 		SrcMAC:       c.Iface.HardwareAddr,
@@ -89,11 +81,10 @@ func (c *BasicConfigurer) arpSendGratuitous() error {
 		FixLengths:       true,
 		ComputeChecksums: true,
 	}
-	err = gopacket.SerializeLayers(buffer, opts, ethLayer, arpLayer)
-	if err != nil {
-		return err
+
+	if err := gopacket.SerializeLayers(buffer, opts, ethLayer, arpLayer); err != nil {
+		return nil, err
 	}
 
-	// Send the packet
-	return handle.WritePacketData(buffer.Bytes())
+	return buffer.Bytes(), nil
 }

ipmanager/basicConfigurer_linux.go

@@ -1,21 +1,51 @@
 package ipmanager
 
 import (
+	"net"
 	"os/exec"
+	"syscall"
 )
 
 const (
 	arpRequestOp = 1
 	arpReplyOp   = 2
 )
 
+func htons(i uint16) uint16 {
+	return (i<<8)&0xff00 | i>>8
+}
+
+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)
+
+	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
+	}
+
+	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 {
-		if err := c.arpSendGratuitous(); err != nil {
-			log.Error("Failed to send gratuitous ARP: ", err)
+		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)
+			}
 		}
 	}
 

ipmanager/basicConfigurer_windows.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)
@@ -26,8 +38,12 @@ func (c *BasicConfigurer) configureAddress() bool {
 		return false
 	}
 
-	if err := c.arpSendGratuitous(); err != nil {
-		log.Error("Failed to send gratuitous ARP: ", err)
+	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
 }