Capturing NGAP messages

[mrramachari]

I wanted to capture ngap messages using this library,I wanted to know if that's possible using this library if yes I wanted some examples. So far I've managed to read sctp and gtp messages.

`package main
import (
    "fmt" // Import the fmt package to print messages to the console.
    "log" // Import the log package to log errors to the console.
    "os"

    "github.com/google/gopacket"        // Import the gopacket package to decode packets.
    "github.com/google/gopacket/layers" // Import the layers package to access the various network layers.
    "github.com/google/gopacket/pcap"   // Import the pcap package to capture packets.
)

func main() {
    // Check if file argument is provided
    if len(os.Args) < 2 {
        fmt.Println("Please provide a pcap file to read")
        os.Exit(1)
    }

    // Open up the pcap file for reading
    handle, err := pcap.OpenOffline(os.Args[1])
    if err != nil {
        log.Fatal(err)
    }
    defer handle.Close()

    // Loop through packets in file
    packetSource := gopacket.NewPacketSource(handle, handle.LinkType())
    for packet := range packetSource.Packets() {

        // Print the packet details
        // fmt.Println(packet.String())

        // // Extract and print the Ethernet layer
        // ethLayer := packet.Layer(layers.LayerTypeEthernet)
        // if ethLayer != nil {
        //  ethPacket, _ := ethLayer.(*layers.Ethernet)
        //  fmt.Println("Ethernet source MAC address:", ethPacket.SrcMAC)
        //  fmt.Println("Ethernet destination MAC address:", ethPacket.DstMAC)
        // }

        // // Extract and print the IP layer
        // ipLayer := packet.Layer(layers.LayerTypeIPv4)
        // if ipLayer != nil {
        //  ipPacket, _ := ipLayer.(*layers.IPv4)
        //  fmt.Println("IP source address:", ipPacket.SrcIP)
        //  fmt.Println("IP destination address:", ipPacket.DstIP)
        // }

        // Extract and check for SCTP layer
        sctpLayer := packet.Layer(layers.LayerTypeSCTP)
        if sctpLayer != nil {
            fmt.Println("SCTP Packet:")
            fmt.Println(packet.String())
            continue // Skip further processing for this packet
        }

        // // Extract and check for GTP layer
        // gtpLayer := packet.Layer(layers.LayerTypeGTP)
        // if gtpLayer != nil {
        //  fmt.Println("GTP Packet:")
        //  fmt.Println(packet.String())
        //  continue // Skip further processing for this packet
        // }
        ngapLayer := packet.Layer(layers.LayerTypeGTPv1U)
        if ngapLayer != nil {
            fmt.Println("GTPv1U Message:")
            fmt.Println(packet.String())
            continue // Skip further processing for this packet
        }
    }
}`