Capture HTTP network packages with gopacket/pcap

http_capture.go

package main

import (
	"github.com/google/gopacket"
	//"github.com/google/gopacket/layers"
	"flag"
	"fmt"
	"github.com/google/gopacket/pcap"
)

func main() {
	var hostname string
	flag.StringVar(&hostname, "hostname", "localhost", "target host name")
	flag.Parse()

	handle, err := pcap.OpenLive("eth0", 1600, true, pcap.BlockForever)
	if err != nil {
		panic(err)
	}
	expr := fmt.Sprintf("host %s and tcp and dst port 80", hostname)
	fmt.Printf("Handling expression %q\n", expr)
	err = handle.SetBPFFilter(expr)
	if err != nil {
		panic(err)
	}
	packetSource := gopacket.NewPacketSource(handle, handle.LinkType())
	for packet := range packetSource.Packets() {
		// Get the TCP layer from this packet
		if app := packet.ApplicationLayer(); app != nil {
			println(string(app.Payload()))
		}
	}
}