blob: 48e46ecf87d1acc5935f9c87971823f1ba5b06f9 [file] [log] [blame]
# Copyright (c) 2013 The Chromium OS Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.
import datetime
import logging
import re
from autotest_lib.client.common_lib import utils
WLAN_PROBE_FILTER = 'wlan type mgt subtype probe-req'
class Frame(object):
"""A frame from a packet capture."""
TIME_FORMAT = "%H:%M:%S.%f"
def __init__(self, frametime, bit_rate, mcs_index, probe_ssid):
self._datetime = frametime
self._bit_rate = bit_rate
self._mcs_index = mcs_index
self._probe_ssid = probe_ssid
def time_datetime(self):
"""The time of the frame, as a |datetime| object."""
return self._datetime
def bit_rate(self):
"""The bitrate used to transmit the frame, as an int."""
return self._bit_rate
def mcs_index(self):
The MCS index used to transmit the frame, as an int.
The value may be None, if the frame was not transmitted
using 802.11n modes.
return self._mcs_index
def probe_ssid(self):
The SSID of the probe request, as a string.
The value may be None, if the frame is not a probe request.
return self._probe_ssid
def time_string(self):
"""The time of the frame, in local time, as a string."""
return self._datetime.strftime(self.TIME_FORMAT)
def get_frames(pcap_path, remote_host=None, pcap_filter='',
Get a parsed representation of the contents of a pcap file.
@param pcap_path: string path to pcap file.
@param remote_host: Host object (if the file is remote).
@param pcap_filter: string filter to apply to captured frames.
@param command_tcpdump: string path of tcpdump command.
@return list of Frame structs.
run =
if remote_host:
run =
result = run('%s -n -tt -r %s "%s"' % (command_tcpdump, pcap_path,
frames = []'Parsing frames')
bad_lines = 0
for frame in result.stdout.splitlines():
match ='^(?P<ts>\d+\.\d{6}).* '
r'(?P<rate>\d+.\d) Mb/s', frame)
if not match:
logging.debug('Found bad tcpdump line: %s', frame)
bad_lines += 1
frame_datetime = datetime.datetime.fromtimestamp(
rate = float('rate'))
match ='MCS (\d+)', frame)
if match:
mcs_index = int(
mcs_index = None
# Note: this fails if the SSID contains a ')'
match ='Probe Request \(([^)]*)\)', frame)
if match:
probe_ssid =
probe_ssid = None
frames.append(Frame(frame_datetime, rate, mcs_index, probe_ssid))
if bad_lines:
logging.error('Failed to parse %d lines.', bad_lines)
return frames
def get_probe_ssids(pcap_path, remote_host=None, probe_sender=None):
Get the SSIDs that were named in 802.11 probe requests frames.
Parse a pcap, returning all the SSIDs named in 802.11 probe
request frames. If |probe_sender| is specified, only probes
from that MAC address will be considered.
@param pcap_path: string path to pcap file.
@param remote_host: Host object (if the file is remote).
@param probe_sender: MAC address of the device sending probes.
@return: A frozenset of the SSIDs that were probed.
if probe_sender:
pcap_filter = '%s and wlan addr2 %s' % (
WLAN_PROBE_FILTER, probe_sender)
pcap_filter = WLAN_PROBE_FILTER
frames = get_frames(pcap_path, remote_host, pcap_filter)
return frozenset(
[frame.probe_ssid for frame in frames
if frame.probe_ssid is not None])