Generate GTPv1-U packet in Go

main.go

package main

import (
        "fmt"
        "net"

        "github.com/google/gopacket"
        "github.com/google/gopacket/layers"
)

func main() {
        icmpPayload := []byte{
                0xe0, 0x57, 0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
                0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f, 0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27,
                0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f, 0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37,
        }
        opts := gopacket.SerializeOptions{FixLengths: true, ComputeChecksums: true}
        buf := gopacket.NewSerializeBuffer()
        iph := &layers.IPv4{
                Version: 4, Protocol: layers.IPProtocolUDP, Flags: layers.IPv4DontFragment, TTL: 64, IHL: 5, Id: 1212,
                SrcIP: net.IP{192, 168, 10, 1}, DstIP: net.IP{192, 168, 10, 5},
        }

        udp := &layers.UDP{SrcPort: 2152, DstPort: 2152}
        udp.SetNetworkLayerForChecksum(iph)

        err := gopacket.SerializeLayers(buf, opts,
                &layers.Ethernet{DstMAC: []byte{0x00, 0x00, 0x5e, 0x00, 0x53, 0x01}, SrcMAC: []byte{0x00, 0x00, 0x5e, 0x00, 0x53, 0x02}, EthernetType: layers.EthernetTypeDot1Q},
                &layers.Dot1Q{VLANIdentifier: 100, Type: layers.EthernetTypeIPv4},
                iph, udp,
                &layers.GTPv1U{Version: 1, ProtocolType: 1, Reserved: 0, ExtensionHeaderFlag: false, SequenceNumberFlag: false, NPDUFlag: false, MessageType: 255, MessageLength: 76, TEID: 2},
                &layers.IPv4{
                        Version: 4, Protocol: layers.IPProtocolICMPv4, Flags: layers.IPv4DontFragment, TTL: 64, IHL: 5, Id: 1160,
                        SrcIP: net.IP{192, 168, 100, 200}, DstIP: net.IP{192, 168, 30, 1},
                },
                &layers.ICMPv4{TypeCode: layers.CreateICMPv4TypeCode(layers.ICMPv4TypeEchoRequest, 0), Id: 1, Seq: 1},
                gopacket.Payload(icmpPayload),
        )
        if err != nil {
                panic(err)
        }
        fmt.Printf("%x", buf.Bytes())
}