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
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
|
// 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.
//go:build linux
package pcapgo_test
import (
"bytes"
"context"
"fmt"
"log"
"os"
"sync/atomic"
"testing"
"time"
"github.com/vishvananda/netlink"
"github.com/gopacket/gopacket"
"github.com/gopacket/gopacket/layers"
"github.com/gopacket/gopacket/pcapgo"
)
const (
timeout = 100 * time.Millisecond
)
func Example_captureEthernet() {
f, err := os.Create("/tmp/lo.pcap")
if err != nil {
log.Fatal(err)
}
defer f.Close()
pcapw := pcapgo.NewWriter(f)
if err := pcapw.WriteFileHeader(1600, layers.LinkTypeEthernet); err != nil {
log.Fatalf("WriteFileHeader: %v", err)
}
handle, err := pcapgo.NewEthernetHandle("lo")
if err != nil {
log.Fatalf("OpenEthernet: %v", err)
}
pkgsrc := gopacket.NewPacketSource(handle, layers.LayerTypeEthernet)
ctx, cancel := context.WithCancel(context.Background())
defer cancel()
for packet := range pkgsrc.PacketsCtx(ctx) {
if err := pcapw.WritePacket(packet.Metadata().CaptureInfo, packet.Data()); err != nil {
log.Fatalf("pcap.WritePacket(): %v", err)
}
}
}
func TestEthernetHandle_Close_WithTimeout(t *testing.T) {
t.Skip("needs root access, skipping")
var (
handle *pcapgo.EthernetHandle
err error
done = make(chan struct{})
)
handle, err = pcapgo.NewEthernetHandle(setupDummyInterface(t))
if err != nil {
t.Fatalf("OpenEthernet: %v", err)
}
ctx, cancel := context.WithTimeout(context.Background(), timeout)
defer cancel()
pkgsrc := gopacket.NewPacketSource(handle, layers.LayerTypeEthernet)
go consumePacketSource(ctx, t, pkgsrc, done)
select {
case _, more := <-done:
if more {
t.Fatalf("done channel is polluted?!")
} else {
t.Log("PacketSource got closed")
}
case <-time.After(2 * timeout):
}
}
func TestEthernetHandle_Close_WithCancel(t *testing.T) {
t.Skip("needs root access, skipping")
var (
handle *pcapgo.EthernetHandle
err error
done = make(chan struct{})
)
handle, err = pcapgo.NewEthernetHandle(setupDummyInterface(t))
if err != nil {
t.Fatalf("OpenEthernet: %v", err)
}
ctx, cancel := context.WithCancel(context.Background())
pkgsrc := gopacket.NewPacketSource(handle, layers.LayerTypeEthernet)
go consumePacketSource(ctx, t, pkgsrc, done)
go func() {
<-time.After(timeout)
cancel()
}()
select {
case _, more := <-done:
if more {
t.Fatalf("done channel is polluted?!")
} else {
t.Log("PacketSource got closed")
}
case <-time.After(2 * timeout):
}
}
func consumePacketSource(ctx context.Context, tb testing.TB, pkgsrc *gopacket.PacketSource, done chan<- struct{}) {
tb.Helper()
var writer = pcapgo.NewWriter(new(bytes.Buffer))
defer close(done)
for packet := range pkgsrc.PacketsCtx(ctx) {
if err := writer.WritePacket(packet.Metadata().CaptureInfo, packet.Data()); err != nil {
tb.Errorf("pcap.WritePacket(): %v", err)
}
}
}
var (
dummyInterfaceIdx int32 = -1
)
// setupDummyInterface configures a dummy interface and returns the generated interface name.
// It assigns an address from the 127.10.0.0/24 network.
// It does not check if there are already more than 254 interfaces.
// If there are the call to netlink.ParseAddr will fail because 127.10.0.256/24 isn't a valid IP address,
// but it should be fine for testing purposes.
func setupDummyInterface(tb testing.TB) (ifName string) {
tb.Helper()
la := netlink.NewLinkAttrs()
idx := atomic.AddInt32(&dummyInterfaceIdx, 1)
la.Name = fmt.Sprintf("dummy%02d", idx)
dummyInterface := &netlink.Dummy{LinkAttrs: la}
if err := netlink.LinkAdd(dummyInterface); err != nil {
tb.Fatalf("netlink.LinkAdd() error = %v", err)
}
var (
link netlink.Link
addr *netlink.Addr
err error
)
link, err = netlink.LinkByName(la.Name)
if err != nil {
tb.Fatalf("netlink.LinkByName() error = %v", err)
}
tb.Cleanup(func() {
if err := netlink.LinkDel(link); err != nil {
tb.Fatalf("netlink.LinkDel() error = %v", err)
}
})
addr, err = netlink.ParseAddr(fmt.Sprintf("127.10.0.%d/24", idx+1))
if err != nil {
tb.Fatalf("netlink.ParseAddr() = %v", err)
}
if err := netlink.AddrAdd(link, addr); err != nil {
tb.Fatalf("netlink.AddrAdd() error = %v", err)
}
if err := netlink.LinkSetUp(link); err != nil {
tb.Fatalf("netlink.LinkSetUp() error = %v", err)
}
return la.Name
}
|
