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// Copyright 2012 Google, Inc. All rights reserved.
//
// Use of this source code is governed by a BSD-style license
// that can be found in the LICENSE file in the root of the source
// tree.
// +build ignore
// This binary tests that PCAP packet capture is working correctly by issuing
// HTTP requests, then making sure we actually capture data off the wire.
package main
import (
"errors"
"flag"
"fmt"
"log"
"net"
"net/http"
"os"
"time"
"github.com/google/gopacket/pcap"
)
var mode = flag.String("mode", "basic", "One of: basic,filtered,timestamp")
func generatePackets() {
if resp, err := http.Get("http://code.google.com"); err != nil {
log.Printf("Could not get HTTP: %v", err)
} else {
resp.Body.Close()
}
}
func main() {
flag.Parse()
ifaces, err := net.Interfaces()
if err != nil {
log.Fatal(err)
}
for _, iface := range ifaces {
log.Printf("Trying capture on %q", iface.Name)
if err := tryCapture(iface); err != nil {
log.Printf("Error capturing on %q: %v", iface.Name, err)
} else {
log.Printf("Successfully captured on %q", iface.Name)
return
}
}
os.Exit(1)
}
func tryCapture(iface net.Interface) error {
if iface.Name[:2] == "lo" {
return errors.New("skipping loopback")
}
var h *pcap.Handle
var err error
switch *mode {
case "basic":
h, err = pcap.OpenLive(iface.Name, 65536, false, time.Second*3)
if err != nil {
return fmt.Errorf("openlive: %v", err)
}
defer h.Close()
case "filtered":
h, err = pcap.OpenLive(iface.Name, 65536, false, time.Second*3)
if err != nil {
return fmt.Errorf("openlive: %v", err)
}
defer h.Close()
if err := h.SetBPFFilter("port 80 or port 443"); err != nil {
return fmt.Errorf("setbpf: %v", err)
}
case "timestamp":
u, err := pcap.NewInactiveHandle(iface.Name)
if err != nil {
return err
}
defer u.CleanUp()
if err = u.SetSnapLen(65536); err != nil {
return err
} else if err = u.SetPromisc(false); err != nil {
return err
} else if err = u.SetTimeout(time.Second * 3); err != nil {
return err
}
sources := u.SupportedTimestamps()
if len(sources) == 0 {
return errors.New("no supported timestamp sources")
} else if err := u.SetTimestampSource(sources[0]); err != nil {
return fmt.Errorf("settimestampsource(%v): %v", sources[0], err)
} else if h, err = u.Activate(); err != nil {
return fmt.Errorf("could not activate: %v", err)
}
defer h.Close()
default:
panic("Invalid --mode: " + *mode)
}
go generatePackets()
h.ReadPacketData() // Do one dummy read to clear any timeouts.
data, ci, err := h.ReadPacketData()
if err != nil {
return fmt.Errorf("readpacketdata: %v", err)
}
log.Printf("Read packet, %v bytes, CI: %+v", len(data), ci)
return nil
}
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