更改目录结构

server/pkg/arpdis/arp.go

@@ -0,0 +1,56 @@
+package arpdis
+
+// Reference: github.com/malfunkt/arpfox
+// TODO now only support IPv4
+
+import (
+	"github.com/google/gopacket"
+	"github.com/google/gopacket/layers"
+)
+
+var defaultSerializeOpts = gopacket.SerializeOptions{
+	FixLengths:       true,
+	ComputeChecksums: true,
+}
+
+// NewARPRequest creates a bew ARP packet of type "request.
+func NewARPRequest(src *Addr, dst *Addr) ([]byte, error) {
+	return buildPacket(src, dst, layers.ARPRequest)
+}
+
+// NewARPReply creates a new ARP packet of type "reply".
+func NewARPReply(src *Addr, dst *Addr) ([]byte, error) {
+	return buildPacket(src, dst, layers.ARPReply)
+}
+
+// buildPacket creates an template ARP packet with the given source and
+// destination.
+func buildPacket(src *Addr, dst *Addr, opt uint16) ([]byte, error) {
+	ether := layers.Ethernet{
+		EthernetType: layers.EthernetTypeARP,
+		SrcMAC:       src.HardwareAddr,
+		DstMAC:       dst.HardwareAddr,
+	}
+	arp := layers.ARP{
+		AddrType: layers.LinkTypeEthernet,
+		Protocol: layers.EthernetTypeIPv4,
+
+		HwAddressSize:   6,
+		ProtAddressSize: 4,
+		Operation:       opt,
+
+		SourceHwAddress:   src.HardwareAddr,
+		SourceProtAddress: src.IP.To4(),
+
+		DstHwAddress:   dst.HardwareAddr,
+		DstProtAddress: dst.IP.To4(),
+	}
+
+	buf := gopacket.NewSerializeBuffer()
+	err := gopacket.SerializeLayers(buf, defaultSerializeOpts, &ether, &arp)
+	if err != nil {
+		return nil, err
+	}
+
+	return buf.Bytes(), nil
+}