1 # Copyright (c) 2013 The Chromium OS Authors. All rights reserved. 2 # Use of this source code is governed by a BSD-style license that can be 3 # found in the LICENSE file. 4 5 import collections 6 import logging 7 import os.path 8 import time 9 import uuid 10 11 from autotest_lib.client.bin import utils 12 from autotest_lib.client.common_lib import error 13 from autotest_lib.client.common_lib.cros import path_utils 14 15 16 class PacketCapturesDisabledError(Exception): 17 """Signifies that this remote host does not support packet captures.""" 18 pass 19 20 21 # local_pcap_path refers to the path of the result on the local host. 22 # local_log_path refers to the tcpdump log file path on the local host. 23 CaptureResult = collections.namedtuple('CaptureResult', 24 ['local_pcap_path', 'local_log_path']) 25 26 # The number of bytes needed for a probe request is hard to define, 27 # because the frame contents are variable (e.g. radiotap header may 28 # contain different fields, maybe SSID isn't the first tagged 29 # parameter?). The value here is 2x the largest frame size observed in 30 # a quick sample. 31 SNAPLEN_WIFI_PROBE_REQUEST = 600 32 33 TCPDUMP_START_TIMEOUT_SECONDS = 5 34 TCPDUMP_START_POLL_SECONDS = 0.1 35 36 def get_packet_capturer(host, host_description=None, cmd_ifconfig=None, 37 cmd_ip=None, cmd_iw=None, cmd_netdump=None, 38 ignore_failures=False): 39 cmd_ifconfig = (cmd_ifconfig or 40 path_utils.get_install_path('ifconfig', host=host)) 41 cmd_iw = cmd_iw or path_utils.get_install_path('iw', host=host) 42 cmd_ip = cmd_ip or path_utils.get_install_path('ip', host=host) 43 cmd_netdump = (cmd_netdump or 44 path_utils.get_install_path('tcpdump', host=host)) 45 host_description = host_description or 'cap_%s' % uuid.uuid4().hex 46 if None in [cmd_ifconfig, cmd_iw, cmd_ip, cmd_netdump, host_description]: 47 if ignore_failures: 48 logging.warning('Creating a disabled packet capturer for %s.', 49 host_description) 50 return DisabledPacketCapturer() 51 else: 52 raise error.TestFail('Missing commands needed for ' 53 'capturing packets') 54 55 return PacketCapturer(host, host_description, cmd_ifconfig, cmd_ip, cmd_iw, 56 cmd_netdump) 57 58 59 class DisabledPacketCapturer(object): 60 """Delegate meant to look like it could take packet captures.""" 61 62 @property 63 def capture_running(self): 64 """@return False""" 65 return False 66 67 68 def __init__(self): 69 pass 70 71 72 def __enter__(self): 73 return self 74 75 76 def __exit__(self): 77 pass 78 79 80 def close(self): 81 """No-op""" 82 83 84 def create_raw_monitor(self, phy, frequency, ht_type=None, 85 monitor_device=None): 86 """Appears to fail while creating a raw monitor device. 87 88 @param phy string ignored. 89 @param frequency int ignored. 90 @param ht_type string ignored. 91 @param monitor_device string ignored. 92 @return None. 93 94 """ 95 return None 96 97 98 def configure_raw_monitor(self, monitor_device, frequency, ht_type=None): 99 """Fails to configure a raw monitor. 100 101 @param monitor_device string ignored. 102 @param frequency int ignored. 103 @param ht_type string ignored. 104 105 """ 106 107 108 def create_managed_monitor(self, existing_dev, monitor_device=None): 109 """Fails to create a managed monitor device. 110 111 @param existing_device string ignored. 112 @param monitor_device string ignored. 113 @return None 114 115 """ 116 return None 117 118 119 def start_capture(self, interface, local_save_dir, 120 remote_file=None, snaplen=None): 121 """Fails to start a packet capture. 122 123 @param interface string ignored. 124 @param local_save_dir string ignored. 125 @param remote_file string ignored. 126 @param snaplen int ignored. 127 128 @raises PacketCapturesDisabledError. 129 130 """ 131 raise PacketCapturesDisabledError() 132 133 134 def stop_capture(self, capture_pid=None): 135 """Stops all ongoing packet captures. 136 137 @param capture_pid int ignored. 138 139 """ 140 141 142 class PacketCapturer(object): 143 """Delegate with capability to initiate packet captures on a remote host.""" 144 145 LIBPCAP_POLL_FREQ_SECS = 1 146 147 @property 148 def capture_running(self): 149 """@return True iff we have at least one ongoing packet capture.""" 150 if self._ongoing_captures: 151 return True 152 153 return False 154 155 156 def __init__(self, host, host_description, cmd_ifconfig, cmd_ip, 157 cmd_iw, cmd_netdump, disable_captures=False): 158 self._cmd_netdump = cmd_netdump 159 self._cmd_iw = cmd_iw 160 self._cmd_ip = cmd_ip 161 self._cmd_ifconfig = cmd_ifconfig 162 self._host = host 163 self._ongoing_captures = {} 164 self._cap_num = 0 165 self._if_num = 0 166 self._created_managed_devices = [] 167 self._created_raw_devices = [] 168 self._host_description = host_description 169 170 171 def __enter__(self): 172 return self 173 174 175 def __exit__(self): 176 self.close() 177 178 179 def close(self): 180 """Stop ongoing captures and destroy all created devices.""" 181 self.stop_capture() 182 for device in self._created_managed_devices: 183 self._host.run("%s dev %s del" % (self._cmd_iw, device)) 184 self._created_managed_devices = [] 185 for device in self._created_raw_devices: 186 self._host.run("%s link set %s down" % (self._cmd_ip, device)) 187 self._host.run("%s dev %s del" % (self._cmd_iw, device)) 188 self._created_raw_devices = [] 189 190 191 def create_raw_monitor(self, phy, frequency, ht_type=None, 192 monitor_device=None): 193 """Create and configure a monitor type WiFi interface on a phy. 194 195 If a device called |monitor_device| already exists, it is first removed. 196 197 @param phy string phy name for created monitor (e.g. phy0). 198 @param frequency int frequency for created monitor to watch. 199 @param ht_type string optional HT type ('HT20', 'HT40+', or 'HT40-'). 200 @param monitor_device string name of monitor interface to create. 201 @return string monitor device name created or None on failure. 202 203 """ 204 if not monitor_device: 205 monitor_device = 'mon%d' % self._if_num 206 self._if_num += 1 207 208 self._host.run('%s dev %s del' % (self._cmd_iw, monitor_device), 209 ignore_status=True) 210 result = self._host.run('%s phy %s interface add %s type monitor' % 211 (self._cmd_iw, 212 phy, 213 monitor_device), 214 ignore_status=True) 215 if result.exit_status: 216 logging.error('Failed creating raw monitor.') 217 return None 218 219 self.configure_raw_monitor(monitor_device, frequency, ht_type) 220 self._created_raw_devices.append(monitor_device) 221 return monitor_device 222 223 224 def configure_raw_monitor(self, monitor_device, frequency, ht_type=None): 225 """Configure a raw monitor with frequency and HT params. 226 227 Note that this will stomp on earlier device settings. 228 229 @param monitor_device string name of device to configure. 230 @param frequency int WiFi frequency to dwell on. 231 @param ht_type string optional HT type ('HT20', 'HT40+', or 'HT40-'). 232 233 """ 234 channel_args = str(frequency) 235 if ht_type: 236 ht_type = ht_type.upper() 237 channel_args = '%s %s' % (channel_args, ht_type) 238 if ht_type not in ('HT20', 'HT40+', 'HT40-'): 239 raise error.TestError('Cannot set HT mode: %s', ht_type) 240 241 self._host.run("%s link set %s up" % (self._cmd_ip, monitor_device)) 242 self._host.run("%s dev %s set freq %s" % (self._cmd_iw, 243 monitor_device, 244 channel_args)) 245 246 247 def create_managed_monitor(self, existing_dev, monitor_device=None): 248 """Create a monitor type WiFi interface next to a managed interface. 249 250 If a device called |monitor_device| already exists, it is first removed. 251 252 @param existing_device string existing interface (e.g. mlan0). 253 @param monitor_device string name of monitor interface to create. 254 @return string monitor device name created or None on failure. 255 256 """ 257 if not monitor_device: 258 monitor_device = 'mon%d' % self._if_num 259 self._if_num += 1 260 self._host.run('%s dev %s del' % (self._cmd_iw, monitor_device), 261 ignore_status=True) 262 result = self._host.run('%s dev %s interface add %s type monitor' % 263 (self._cmd_iw, 264 existing_dev, 265 monitor_device), 266 ignore_status=True) 267 if result.exit_status: 268 logging.warning('Failed creating monitor.') 269 return None 270 271 self._host.run('%s %s up' % (self._cmd_ifconfig, monitor_device)) 272 self._created_managed_devices.append(monitor_device) 273 return monitor_device 274 275 276 def _is_capture_active(self, remote_log_file): 277 """Check if a packet capture has completed initialization. 278 279 @param remote_log_file string path to the capture's log file 280 @return True iff log file indicates that tcpdump is listening. 281 """ 282 return self._host.run( 283 'grep "listening on" "%s"' % remote_log_file, ignore_status=True 284 ).exit_status == 0 285 286 287 def start_capture(self, interface, local_save_dir, 288 remote_file=None, snaplen=None): 289 """Start a packet capture on an existing interface. 290 291 @param interface string existing interface to capture on. 292 @param local_save_dir string directory on local machine to hold results. 293 @param remote_file string full path on remote host to hold the capture. 294 @param snaplen int maximum captured frame length. 295 @return int pid of started packet capture. 296 297 """ 298 remote_file = (remote_file or 299 '/tmp/%s.%d.pcap' % (self._host_description, 300 self._cap_num)) 301 self._cap_num += 1 302 remote_log_file = '%s.log' % remote_file 303 # Redirect output because SSH refuses to return until the child file 304 # descriptors are closed. 305 cmd = '%s -U -i %s -w %s -s %d >%s 2>&1 & echo $!' % ( 306 self._cmd_netdump, 307 interface, 308 remote_file, 309 snaplen or 0, 310 remote_log_file) 311 logging.debug('Starting managed packet capture') 312 pid = int(self._host.run(cmd).stdout) 313 self._ongoing_captures[pid] = (remote_file, 314 remote_log_file, 315 local_save_dir) 316 is_capture_active = lambda: self._is_capture_active(remote_log_file) 317 utils.poll_for_condition( 318 is_capture_active, 319 timeout=TCPDUMP_START_TIMEOUT_SECONDS, 320 sleep_interval=TCPDUMP_START_POLL_SECONDS, 321 desc='Timeout waiting for tcpdump to start.') 322 return pid 323 324 325 def stop_capture(self, capture_pid=None, local_save_dir=None, 326 local_pcap_filename=None): 327 """Stop an ongoing packet capture, or all ongoing packet captures. 328 329 If |capture_pid| is given, stops that capture, otherwise stops all 330 ongoing captures. 331 332 This method will sleep for a small amount of time, to ensure that 333 libpcap has completed its last poll(). The caller must ensure that 334 no unwanted traffic is received during this time. 335 336 @param capture_pid int pid of ongoing packet capture or None. 337 @param local_save_dir path to directory to save pcap file in locally. 338 @param local_pcap_filename name of file to store pcap in 339 (basename only). 340 @return list of RemoteCaptureResult tuples 341 342 """ 343 time.sleep(self.LIBPCAP_POLL_FREQ_SECS * 2) 344 345 if capture_pid: 346 pids_to_kill = [capture_pid] 347 else: 348 pids_to_kill = list(self._ongoing_captures.keys()) 349 350 results = [] 351 for pid in pids_to_kill: 352 self._host.run('kill -INT %d' % pid, ignore_status=True) 353 remote_pcap, remote_pcap_log, save_dir = self._ongoing_captures[pid] 354 pcap_filename = os.path.basename(remote_pcap) 355 pcap_log_filename = os.path.basename(remote_pcap_log) 356 if local_pcap_filename: 357 pcap_filename = os.path.join(local_save_dir or save_dir, 358 local_pcap_filename) 359 pcap_log_filename = os.path.join(local_save_dir or save_dir, 360 '%s.log' % local_pcap_filename) 361 pairs = [(remote_pcap, pcap_filename), 362 (remote_pcap_log, pcap_log_filename)] 363 364 for remote_file, local_file in pairs: 365 self._host.get_file(remote_file, local_file) 366 self._host.run('rm -f %s' % remote_file) 367 368 self._ongoing_captures.pop(pid) 369 results.append(CaptureResult(pcap_filename, 370 pcap_log_filename)) 371 return results 372
