func newPcapIO(ifName string, promisc bool, snaplen int, bufSz int) (handle *PcapIO, err error) {
inactive, err := pcap.NewInactiveHandle(ifName)
if err != nil {
return
}
defer inactive.CleanUp()
if err = inactive.SetPromisc(promisc); err != nil {
return
}
if err = inactive.SetSnapLen(snaplen); err != nil {
return
}
if err = inactive.SetTimeout(-1); err != nil {
return
}
if err = inactive.SetImmediateMode(true); err != nil {
return
}
if err = inactive.SetBufferSize(bufSz); err != nil {
return
}
active, err := inactive.Activate()
if err != nil {
return
}
if err = active.SetDirection(pcap.DirectionIn); err != nil {
return
}
return &PcapIO{handle: active}, nil
}
func tryCapture(iface net.Interface) error {
if iface.Name[:2] == "lo" {
return fmt.Errorf("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 fmt.Errorf("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
}
func newPcapIO(ifName string, promisc bool, snaplen int, bufSz int) (handle *PcapIO, err error) {
inactive, err := pcap.NewInactiveHandle(ifName)
if err != nil {
return
}
defer inactive.CleanUp()
if err = inactive.SetPromisc(promisc); err != nil {
return
}
if err = inactive.SetSnapLen(snaplen); err != nil {
return
}
if err = inactive.SetTimeout(MaxDuration); err != nil {
return
}
if err = inactive.SetImmediateMode(true); err != nil {
// If gopacket is compiled against an older pcap.h that
// doesn't have pcap_set_immediate_mode, it supplies a dummy
// definition that always returns PCAP_ERROR. That becomes
// "Generic error", which is not very helpful. The real
// pcap_set_immediate_mode never returns PCAP_ERROR, so this
// turns it into a more informative message.
if fmt.Sprint(err) == "Generic error" {
err = fmt.Errorf("compiled against an old version of libpcap; please compile against libpcap-1.5.0 or later")
}
return
}
if err = inactive.SetBufferSize(bufSz); err != nil {
return
}
active, err := inactive.Activate()
if err != nil {
return
}
if err = active.SetDirection(pcap.DirectionIn); err != nil {
return
}
return &PcapIO{handle: active}, nil
}