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
|
// 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.
// Package dumpcommand implements a run function for pfdump and pcapdump
// with many similar flags/features to tcpdump. This code is split out seperate
// from data sources (pcap/pfring) so it can be used by both.
package dumpcommand
import (
"flag"
"fmt"
"log"
"os"
"time"
"github.com/google/gopacket"
"github.com/google/gopacket/ip4defrag"
"github.com/google/gopacket/layers" // pulls in all layers decoders
)
var (
print = flag.Bool("print", true, "Print out packets, if false only prints out statistics")
maxcount = flag.Int("c", -1, "Only grab this many packets, then exit")
decoder = flag.String("decoder", "Ethernet", "Name of the decoder to use")
dump = flag.Bool("X", false, "If true, dump very verbose info on each packet")
statsevery = flag.Int("stats", 1000, "Output statistics every N packets")
printErrors = flag.Bool("errors", false, "Print out packet dumps of decode errors, useful for checking decoders against live traffic")
lazy = flag.Bool("lazy", false, "If true, do lazy decoding")
defrag = flag.Bool("defrag", false, "If true, do IPv4 defrag")
)
func Run(src gopacket.PacketDataSource) {
if !flag.Parsed() {
log.Fatalln("Run called without flags.Parse() being called")
}
var dec gopacket.Decoder
var ok bool
if dec, ok = gopacket.DecodersByLayerName[*decoder]; !ok {
log.Fatalln("No decoder named", *decoder)
}
source := gopacket.NewPacketSource(src, dec)
source.Lazy = *lazy
source.NoCopy = true
source.DecodeStreamsAsDatagrams = true
fmt.Fprintln(os.Stderr, "Starting to read packets")
count := 0
bytes := int64(0)
start := time.Now()
errors := 0
truncated := 0
layertypes := map[gopacket.LayerType]int{}
defragger := ip4defrag.NewIPv4Defragmenter()
for packet := range source.Packets() {
count++
bytes += int64(len(packet.Data()))
// defrag the IPv4 packet if required
if *defrag {
ip4Layer := packet.Layer(layers.LayerTypeIPv4)
if ip4Layer == nil {
continue
}
ip4 := ip4Layer.(*layers.IPv4)
l := ip4.Length
newip4, err := defragger.DefragIPv4(ip4)
if err != nil {
log.Fatalln("Error while de-fragmenting", err)
} else if newip4 == nil {
continue // packet fragment, we don't have whole packet yet.
}
if newip4.Length != l {
fmt.Printf("Decoding re-assembled packet: %s\n", newip4.NextLayerType())
pb, ok := packet.(gopacket.PacketBuilder)
if !ok {
panic("Not a PacketBuilder")
}
nextDecoder := newip4.NextLayerType()
nextDecoder.Decode(newip4.Payload, pb)
}
}
if *dump {
fmt.Println(packet.Dump())
} else if *print {
fmt.Println(packet)
}
if !*lazy || *print || *dump { // if we've already decoded all layers...
for _, layer := range packet.Layers() {
layertypes[layer.LayerType()]++
}
if packet.Metadata().Truncated {
truncated++
}
if errLayer := packet.ErrorLayer(); errLayer != nil {
errors++
if *printErrors {
fmt.Println("Error:", errLayer.Error())
fmt.Println("--- Packet ---")
fmt.Println(packet.Dump())
}
}
}
done := *maxcount > 0 && count >= *maxcount
if count%*statsevery == 0 || done {
fmt.Fprintf(os.Stderr, "Processed %v packets (%v bytes) in %v, %v errors and %v truncated packets\n", count, bytes, time.Since(start), errors, truncated)
if len(layertypes) > 0 {
fmt.Fprintf(os.Stderr, "Layer types seen: %+v\n", layertypes)
}
}
if done {
break
}
}
}
|
