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#!/usr/bin/python
# Copyright 2012 Google, Inc. All rights reserved.
"""TestCreator creates test templates from pcap files."""
import argparse
import base64
import glob
import re
import string
import subprocess
import sys
class Packet(object):
"""Helper class encapsulating packet from a pcap file."""
def __init__(self, packet_lines):
self.packet_lines = packet_lines
self.data = self._DecodeText(packet_lines)
@classmethod
def _DecodeText(cls, packet_lines):
packet_bytes = []
# First line is timestamp and stuff, skip it.
# Format: 0x0010: 0000 0020 3aff 3ffe 0000 0000 0000 0000 ....:.?.........
for line in packet_lines[1:]:
m = re.match(r'\s+0x[a-f\d]+:\s+((?:[\da-f]{2,4}\s)*)', line, re.IGNORECASE)
if m is None: continue
for hexpart in m.group(1).split():
packet_bytes.append(base64.b16decode(hexpart.upper()))
return ''.join(packet_bytes)
def Test(self, name, link_type):
"""Yields a test using this packet, as a set of lines."""
yield '// testPacket%s is the packet:' % name
for line in self.packet_lines:
yield '// ' + line
yield 'var testPacket%s = []byte{' % name
data = list(self.data)
while data:
linebytes, data = data[:16], data[16:]
yield ''.join(['\t'] + ['0x%02x, ' % ord(c) for c in linebytes])
yield '}'
yield 'func TestPacket%s(t *testing.T) {' % name
yield '\tp := gopacket.NewPacket(testPacket%s, LinkType%s, gopacket.Default)' % (name, link_type)
yield '\tif p.ErrorLayer() != nil {'
yield '\t\tt.Error("Failed to decode packet:", p.ErrorLayer().Error())'
yield '\t}'
yield '\tcheckLayers(p, []gopacket.LayerType{LayerType%s, FILL_ME_IN_WITH_ACTUAL_LAYERS}, t)' % link_type
yield '}'
yield 'func BenchmarkDecodePacket%s(b *testing.B) {' % name
yield '\tfor i := 0; i < b.N; i++ {'
yield '\t\tgopacket.NewPacket(testPacket%s, LinkType%s, gopacket.NoCopy)' % (name, link_type)
yield '\t}'
yield '}'
def GetTcpdumpOutput(filename):
"""Runs tcpdump on the given file, returning output as string."""
return subprocess.check_output(
['tcpdump', '-XX', '-s', '0', '-n', '-r', filename])
def TcpdumpOutputToPackets(output):
"""Reads a pcap file with TCPDump, yielding Packet objects."""
pdata = []
for line in output.splitlines():
if line[0] not in string.whitespace and pdata:
yield Packet(pdata)
pdata = []
pdata.append(line)
if pdata:
yield Packet(pdata)
def main():
class CustomHelpFormatter(argparse.ArgumentDefaultsHelpFormatter):
def _format_usage(self, usage, actions, groups, prefix=None):
header =('TestCreator creates gopacket tests using a pcap file.\n\n'
'Tests are written to standard out... they can then be \n'
'copied into the file of your choice and modified as \n'
'you see.\n\n')
return header + argparse.ArgumentDefaultsHelpFormatter._format_usage(
self, usage, actions, groups, prefix)
parser = argparse.ArgumentParser(formatter_class=CustomHelpFormatter)
parser.add_argument('--link_type', default='Ethernet', help='the link type (default: %(default)s)')
parser.add_argument('--name', default='Packet%d', help='the layer type, must have "%d" inside it')
parser.add_argument('files', metavar='file.pcap', type=str, nargs='+', help='the files to process')
args = parser.parse_args()
for arg in args.files:
for path in glob.glob(arg):
for i, packet in enumerate(TcpdumpOutputToPackets(GetTcpdumpOutput(path))):
print '\n'.join(packet.Test(
args.name % i, args.link_type))
if __name__ == '__main__':
main()
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