Create a packet from raw bytes and write to pcap file using gopacket

I want to create a packet from raw bytes using gopacket and write the packets to a pcap file.

I created a UDP packet from raw bytes as below.

package main
import (
"fmt"
"net"
"log"
"os"
"time"
//"encoding/hex"
"github.com/google/gopacket"
"github.com/google/gopacket/layers"
"github.com/google/gopacket/pcap"
"github.com/google/gopacket/pcapgo"
)
var (
device       string = "eth0"
snapshot_len int32  = 65535
promiscuous  bool   = false
err          error
timeout      time.Duration = 30 * time.Second
handle       *pcap.Handle
buffer       gopacket.SerializeBuffer
options      gopacket.SerializeOptions
)
func main() {
ethernetLayer := &layers.Ethernet{
SrcMAC: net.HardwareAddr{0xFF, 0xAA, 0xFA, 0xAA, 0xFF, 0xAA},
DstMAC: net.HardwareAddr{0xBD, 0xBD, 0xBD, 0xBD, 0xBD, 0xBD},
}
ipLayer := &layers.IPv4{
SrcIP: net.IP{127,0,0,1},
DstIP: net.IP{8,8,8,8},
}
udpLayer := &layers.UDP{
SrcPort: 51190,
DstPort: 4789,
}
rawBytes := []byte{10, 20, 30}
buffer = gopacket.NewSerializeBuffer()
gopacket.SerializeLayers(buffer, options,
ethernetLayer,
ipLayer,
udpLayer,
gopacket.Payload(rawBytes),
)
outgoingPacket := buffer.Bytes()
fmt.Println(outgoingPacket)
ethpacket := gopacket.NewPacket(outgoingPacket,
layers.LayerTypeEthernet,
gopacket.Default )

I am struck how to write these packets to a pcap file. This is that part of the code.

        f, err := os.Create("temp.pcap")
if err != nil {
log.Fatal(err)
os.Exit(1)
}
defer f.Close()
//handle, err = pcap.OpenLive(device, snapshot_len, promiscuous, timeout)
//if err != nil {
//        log.Fatal(err)
//}
//defer handle.Close()
//handle.WritePacketData(outgoingPacket)
w := pcapgo.NewWriter(f)
w.WriteFileHeader(uint32(snapshot_len), layers.LinkTypeEthernet)
w.WritePacket(ethpacket.Metadata().CaptureInfo, ethpacket.Data())

This is the error I am getting. Please help how to proceed further

[root@centos-sqa-blr01 gopacket]# go run create_pcap.go
#command-line-arguments
./create_pcap.go:75:26: packet.MetaData undefined (type gopacket.Packet has no field or method MetaData, but does have Metadata)

Notice the error info: "MetaData" is not "Metadata".

Guess you need to modify:

-            w.WritePacket(packet.MetaData().CaptureInfo, ethpacket.Data())
+            w.WritePacket(packet.Metadata().CaptureInfo, ethpacket.Data())

UPDATE:

If u just want to create and write a packet, comment the following codes. It works for me.

	// handle, err = pcap.OpenLive(device, snapshot_len, promiscuous, timeout)
	// if err != nil {
	// 	log.Fatal(err)
	// }
	// defer handle.Close()