forked from weaveworks/weave
-
Notifications
You must be signed in to change notification settings - Fork 0
/
pcap.go
85 lines (76 loc) · 2.18 KB
/
pcap.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
package router
import (
"code.google.com/p/gopacket/pcap"
"fmt"
)
type PcapIO struct {
handle *pcap.Handle
}
func NewPcapIO(ifName string, bufSz int) (PacketSourceSink, error) {
pio, err := newPcapIO(ifName, true, 65535, bufSz)
if err != nil {
return pio, err
}
// Under Linux, libpcap implements the SetDirection filtering
// in userspace. So set a BPF filter to discard outbound
// packets inside the kernel. We do this here rather than in
// newPcapIO because libpcap doesn't like this in combination
// with a 0 snaplen.
err = pio.handle.SetBPFFilter("inbound")
return pio, err
}
func NewPcapO(ifName string) (po PacketSink, err error) {
po, err = newPcapIO(ifName, false, 0, 0)
return
}
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
}
func (pi *PcapIO) ReadPacket() (data []byte, err error) {
for {
data, _, err = pi.handle.ZeroCopyReadPacketData()
if err == nil || err != pcap.NextErrorTimeoutExpired {
break
}
}
return
}
func (po *PcapIO) WritePacket(data []byte) error {
return po.handle.WritePacketData(data)
}