| # 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 logging |
| import multiprocessing |
| import re |
| import select |
| import time |
| |
| from autotest_lib.client.common_lib import error |
| from autotest_lib.client.common_lib.cros.network import ping_runner |
| from autotest_lib.client.common_lib.cros.network import xmlrpc_datatypes |
| from autotest_lib.server import site_attenuator |
| from autotest_lib.server.cros.network import hostap_config |
| from autotest_lib.server.cros.network import rvr_test_base |
| |
| class Reporter(object): |
| """Object that forwards stdout from Host.run to a pipe. |
| |
| The |stdout_tee| parameter for Host.run() requires an object that looks |
| like a Python built-in file. In particular, it needs 'flush', which a |
| multiprocessing.Connection (the object returned by multiprocessing.Pipe) |
| doesn't have. This wrapper provides that functionaly in order to allow a |
| pipe to be the target of a stdout_tee. |
| |
| """ |
| |
| def __init__(self, write_pipe): |
| """Initializes reporter. |
| |
| @param write_pipe: the place to send output. |
| |
| """ |
| self._write_pipe = write_pipe |
| |
| |
| def flush(self): |
| """Flushes the output - not used by the pipe.""" |
| pass |
| |
| |
| def close(self): |
| """Closes the pipe.""" |
| return self._write_pipe.close() |
| |
| |
| def fileno(self): |
| """Returns the file number of the pipe.""" |
| return self._write_pipe.fileno() |
| |
| |
| def write(self, string): |
| """Write to the pipe. |
| |
| @param string: the string to write to the pipe. |
| |
| """ |
| self._write_pipe.send(string) |
| |
| |
| def writelines(self, sequence): |
| """Write a number of lines to the pipe. |
| |
| @param sequence: the array of lines to be written. |
| |
| """ |
| for string in sequence: |
| self._write_pipe.send(string) |
| |
| |
| class LaunchIwEvent(object): |
| """Calls 'iw event' and searches for a list of events in its output. |
| |
| This class provides a framework for launching 'iw event' in its own |
| process and searching its output for an ordered list of events expressed |
| as regular expressions. |
| |
| Expected to be called as follows: |
| launch_iw_event = LaunchIwEvent('iw', |
| self.context.client.host, |
| timeout_seconds=60.0) |
| # Do things that cause nl80211 traffic |
| |
| # Now, wait for the results you want. |
| if not launch_iw_event.wait_for_events(['RSSI went below threshold', |
| 'scan started', |
| # ... |
| 'connected to']): |
| raise error.TestFail('Did not find all expected events') |
| |
| """ |
| # A timeout from Host.run(timeout) kills the process and that takes a |
| # few seconds. Therefore, we need to add some margin to the select |
| # timeout (which will kill the process if Host.run(timeout) fails for some |
| # reason). |
| TIMEOUT_MARGIN_SECONDS = 5 |
| |
| def __init__(self, iw_command, dut, timeout_seconds): |
| """Launches 'iw event' process with communication channel for output |
| |
| @param dut: Host object for the dut |
| @param timeout_seconds: timeout for 'iw event' (since it never |
| returns) |
| |
| """ |
| self._iw_command = iw_command |
| self._dut = dut |
| self._timeout_seconds = timeout_seconds |
| self._pipe_reader, pipe_writer = multiprocessing.Pipe() |
| self._iw_event = multiprocessing.Process(target=self.do_iw, |
| args=(pipe_writer, |
| self._timeout_seconds,)) |
| self._iw_event.start() |
| |
| |
| def do_iw(self, connection, timeout_seconds): |
| """Runs 'iw event' |
| |
| iw results are passed back, on the fly, through a supplied connection |
| object. The process terminates itself after a specified timeout. |
| |
| @param connection: a Connection object to which results are written. |
| @param timeout_seconds: number of seconds before 'iw event' is killed. |
| |
| """ |
| reporter = Reporter(connection) |
| # ignore_timeout just ignores the _exception_; the timeout is still |
| # valid. |
| self._dut.run('%s event' % self._iw_command, |
| timeout=timeout_seconds, |
| stdout_tee=reporter, |
| ignore_timeout=True) |
| |
| |
| def wait_for_events(self, expected_events): |
| """Waits for 'expected_events' (in order) from iw. |
| |
| @param expected_events: a list of strings that are regular expressions. |
| This method searches for the each expression, in the order that they |
| appear in |expected_events|, in the stream of output from iw. x |
| |
| @returns: True if all events were found. False, otherwise. |
| |
| """ |
| if not expected_events: |
| logging.error('No events') |
| return False |
| |
| expected_event = expected_events.pop(0) |
| done_time = (time.time() + self._timeout_seconds + |
| LaunchIwEvent.TIMEOUT_MARGIN_SECONDS) |
| received_event_log = [] |
| while expected_event: |
| timeout = done_time - time.time() |
| if timeout <= 0: |
| break |
| (sread, swrite, sexec) = select.select( |
| [self._pipe_reader], [], [], timeout) |
| if sread: |
| received_event = sread[0].recv() |
| received_event_log.append(received_event) |
| if re.search(expected_event, received_event): |
| logging.info('Found expected event: "%s"', |
| received_event.rstrip()) |
| if expected_events: |
| expected_event = expected_events.pop(0) |
| else: |
| expected_event = None |
| logging.info('Found ALL expected events') |
| break |
| else: # Timeout. |
| break |
| |
| if expected_event: |
| logging.error('Never found expected event "%s". iw log:', |
| expected_event) |
| for event in received_event_log: |
| logging.error(event.rstrip()) |
| return False |
| return True |
| |
| |
| class network_WiFi_RoamOnLowPower(rvr_test_base.RvRTestBase): |
| """Tests roaming to an AP when the old one's signal is too weak. |
| |
| This test uses a dual-radio Stumpy as the AP and configures the radios to |
| broadcast two BSS's with different frequencies on the same SSID. The DUT |
| connects to the first radio, the test attenuates that radio, and the DUT |
| is supposed to roam to the second radio. |
| |
| This test requires a particular configuration of test equipment: |
| |
| +--------- StumpyCell/AP ----------+ |
| | chromeX.grover.hostY.router.cros | |
| | | |
| | [Radio 0] [Radio 1] | |
| +--------A-----B----C-----D--------+ |
| +------ BeagleBone ------+ | | | | |
| | chromeX.grover.hostY. | | X | X |
| | attenuator.cros [Port0]-[attenuator] | |
| | [Port1]----- | ----[attenuator] |
| | [Port2]-X | | |
| | [Port3]-X +-----+ | |
| | | | | |
| +------------------------+ | | |
| +--------------E----F--------------+ |
| | [Radio 0] | |
| | | |
| | chromeX.grover.hostY.cros | |
| +-------------- DUT ---------------+ |
| |
| Where antennas A, C, and E are the primary antennas for AP/radio0, |
| AP/radio1, and DUT/radio0, respectively; and antennas B, D, and F are the |
| auxilliary antennas for AP/radio0, AP/radio1, and DUT/radio0, |
| respectively. The BeagleBone controls 2 attenuators that are connected |
| to the primary antennas of AP/radio0 and 1 which are fed into the primary |
| and auxilliary antenna ports of DUT/radio 0. Ports 2 and 3 of the |
| BeagleBone as well as the auxillary antennae of AP/radio0 and 1 are |
| terminated. |
| |
| This arrangement ensures that the attenuator port numbers are assigned to |
| the primary radio, first, and the secondary radio, second. If this happens, |
| the ports will be numbered in the order in which the AP's channels are |
| configured (port 0 is first, port 1 is second, etc.). |
| |
| This test is a de facto test that the ports are configured in that |
| arrangement since swapping Port0 and Port1 would cause us to attenuate the |
| secondary radio, providing no impetus for the DUT to switch radios and |
| causing the test to fail to connect at radio 1's frequency. |
| |
| """ |
| |
| version = 1 |
| |
| FREQUENCY_0 = 2412 |
| FREQUENCY_1 = 2462 |
| PORT_0 = 0 # Port created first (on FREQUENCY_0) |
| PORT_1 = 1 # Port created second (on FREQUENCY_1) |
| |
| # Supplicant's signal to noise threshold for roaming. When noise is |
| # measurable and S/N is less than the threshold, supplicant will attempt |
| # to roam. We're setting the roam threshold (and setting it so high -- |
| # it's usually 18) because some of the DUTs we're using have a hard time |
| # measuring signals below -55 dBm. A threshold of 40 roams when the |
| # signal is about -50 dBm (since the noise tends to be around -89). |
| ABSOLUTE_ROAM_THRESHOLD_DB = 40 |
| |
| |
| def run_once(self): |
| """Test body.""" |
| self.context.client.clear_supplicant_blacklist() |
| |
| with self.context.client.roam_threshold( |
| self.ABSOLUTE_ROAM_THRESHOLD_DB): |
| logging.info('- Configure first AP & connect') |
| self.context.configure(hostap_config.HostapConfig( |
| frequency=self.FREQUENCY_0, |
| mode=hostap_config.HostapConfig.MODE_11G)) |
| router_ssid = self.context.router.get_ssid() |
| self.context.assert_connect_wifi(xmlrpc_datatypes. |
| AssociationParameters( |
| ssid=router_ssid)) |
| self.context.assert_ping_from_dut() |
| |
| # Setup background scan configuration to set a signal level, below |
| # which, supplicant will scan (3dB below the current level). We |
| # must reconnect for these parameters to take effect. |
| logging.info('- Set background scan level') |
| bgscan_config = xmlrpc_datatypes.BgscanConfiguration( |
| method='simple', |
| signal=self.context.client.wifi_signal_level - 3) |
| self.context.client.shill.disconnect(router_ssid) |
| self.context.assert_connect_wifi( |
| xmlrpc_datatypes.AssociationParameters( |
| ssid=router_ssid, bgscan_config=bgscan_config)) |
| |
| logging.info('- Configure second AP') |
| self.context.configure(hostap_config.HostapConfig( |
| ssid=router_ssid, |
| frequency=self.FREQUENCY_1, |
| mode=hostap_config.HostapConfig.MODE_11G), |
| multi_interface=True) |
| |
| launch_iw_event = LaunchIwEvent('iw', |
| self.context.client.host, |
| timeout_seconds=60.0) |
| |
| logging.info('- Drop the power on the first AP') |
| |
| self.set_signal_to_force_roam(port=self.PORT_0, |
| frequency=self.FREQUENCY_0) |
| |
| # Verify that the low signal event is generated, that supplicant |
| # scans as a result (or, at least, that supplicant scans after the |
| # threshold is passed), and that it connects to something. |
| logging.info('- Wait for RSSI threshold drop, scan, and connect') |
| if not launch_iw_event.wait_for_events(['RSSI went below threshold', |
| 'scan started', |
| 'connected to']): |
| raise error.TestFail('Did not find all expected events') |
| |
| logging.info('- Wait for a connection on the second AP') |
| # Instead of explicitly connecting, just wait to see if the DUT |
| # connects to the second AP by itself |
| self.context.wait_for_connection(ssid=router_ssid, |
| freq=self.FREQUENCY_1, ap_num=1) |
| |
| # Clean up. |
| self.context.router.deconfig() |
| |
| |
| def set_signal_to_force_roam(self, port, frequency): |
| """Adjust the AP attenuation to force the DUT to roam. |
| |
| wpa_supplicant (v2.0-devel) decides when to roam based on a number of |
| factors even when we're only interested in the scenario when the roam |
| is instigated by an RSSI drop. The gates for roaming differ between |
| systems that have drivers that measure noise and those that don't. If |
| the driver reports noise, the S/N of both the current BSS and the |
| target BSS is capped at 30 and then the following conditions must be |
| met: |
| |
| 1) The S/N of the current AP must be below supplicant's roam |
| threshold. |
| 2) The S/N of the roam target must be more than 3dB larger than |
| that of the current BSS. |
| |
| If the driver does not report noise, the following condition must be |
| met: |
| |
| 3) The roam target's signal must be above the current BSS's signal |
| by a signal-dependent value (that value doesn't currently go |
| higher than 5). |
| |
| This would all be enough complication. Unfortunately, the DUT's signal |
| measurement hardware has typically not been optimized for accurate |
| measurement throughout the signal range. Based on some testing |
| (crbug:295752), it was discovered that the DUT's measurements of signal |
| levels somewhere below -50dBm show values greater than the actual signal |
| and with quite a bit of variance. Since wpa_supplicant uses this same |
| mechanism to read its levels, this code must iterate to find values that |
| will reliably trigger supplicant to roam to the second AP. |
| |
| It was also shown that some MIMO DUTs send different signal levels to |
| their two radios (testing has shown this to be somewhere around 5dB to |
| 7dB). |
| |
| @param port: the beaglebone port that is desired to be attenuated. |
| @param frequency: noise needs to be read for a frequency. |
| |
| """ |
| # wpa_supplicant calls an S/N of 30 dB "quite good signal" and caps the |
| # S/N at this level for the purposes of roaming calculations. We'll do |
| # the same (since we're trying to instigate behavior in supplicant). |
| GREAT_SNR = 30 |
| |
| # The difference between the S/Ns of APs from 2), above. |
| MIN_AP_SIGNAL_DIFF_FOR_ROAM_DB = 3 |
| |
| # The maximum delta for a system that doesn't measure noise, from 3), |
| # above. |
| MIN_NOISELESS_SIGNAL_DIFF_FOR_ROAM_DB = 5 |
| |
| # Adds a clear margin to attenuator levels to make sure that we |
| # attenuate enough to do the job in light of signal and noise levels |
| # that bounce around. This value was reached empirically and further |
| # tweaking may be necessary if this test gets flaky. |
| SIGNAL_TO_NOISE_MARGIN_DB = 3 |
| |
| # The measured difference between the radios on one of our APs. |
| # TODO(wdg): dynamically measure the difference between the AP's radios |
| # (crbug:307678). |
| TEST_HW_SIGNAL_DELTA_DB = 7 |
| |
| # wpa_supplicant's roaming algorithm differs between systems that can |
| # measure noise and those that can't. This code tracks those |
| # differences. |
| actual_signal_dbm = self.context.client.wifi_signal_level |
| actual_noise_dbm = self.context.client.wifi_noise_level(frequency) |
| logging.info('Radio 0 signal: %r, noise: %r', actual_signal_dbm, |
| actual_noise_dbm) |
| if actual_noise_dbm is not None: |
| system_measures_noise = True |
| actual_snr_db = actual_signal_dbm - actual_noise_dbm |
| radio1_snr_db = actual_snr_db - TEST_HW_SIGNAL_DELTA_DB |
| |
| # Supplicant will cap any S/N measurement used for roaming at |
| # GREAT_SNR so we'll do the same. |
| if radio1_snr_db > GREAT_SNR: |
| radio1_snr_db = GREAT_SNR |
| |
| # In order to roam, the S/N of radio 0 must be both less than 3db |
| # below radio1 and less than the roam threshold. |
| logging.info('Radio 1 S/N = %d', radio1_snr_db) |
| delta_snr_threshold_db = (radio1_snr_db - |
| MIN_AP_SIGNAL_DIFF_FOR_ROAM_DB) |
| if (delta_snr_threshold_db < self.ABSOLUTE_ROAM_THRESHOLD_DB): |
| target_snr_db = delta_snr_threshold_db |
| logging.info('Target S/N = %d (delta algorithm)', |
| target_snr_db) |
| else: |
| target_snr_db = self.ABSOLUTE_ROAM_THRESHOLD_DB |
| logging.info('Target S/N = %d (threshold algorithm)', |
| target_snr_db) |
| |
| # Add some margin. |
| target_snr_db -= SIGNAL_TO_NOISE_MARGIN_DB |
| attenuation_db = actual_snr_db - target_snr_db |
| logging.info('Noise: target S/N=%d attenuation=%r', |
| target_snr_db, attenuation_db) |
| else: |
| system_measures_noise = False |
| # On a system that doesn't measure noise, supplicant needs the |
| # signal from radio 0 to be less than that of radio 1 minus a fixed |
| # delta value. While we're here, subtract additional margin from |
| # the target value. |
| target_signal_dbm = (actual_signal_dbm - TEST_HW_SIGNAL_DELTA_DB - |
| MIN_NOISELESS_SIGNAL_DIFF_FOR_ROAM_DB - |
| SIGNAL_TO_NOISE_MARGIN_DB) |
| attenuation_db = actual_signal_dbm - target_signal_dbm |
| logging.info('No noise: target_signal=%r, attenuation=%r', |
| target_signal_dbm, attenuation_db) |
| |
| # Attenuate, measure S/N, repeat (due to flaky measurments) until S/N is |
| # where we want it. |
| keep_tweaking_snr = True |
| while keep_tweaking_snr: |
| # Keep attenuation values below the attenuator's maximum. |
| if attenuation_db > (site_attenuator.Attenuator. |
| MAX_VARIABLE_ATTENUATION): |
| attenuation_db = (site_attenuator.Attenuator. |
| MAX_VARIABLE_ATTENUATION) |
| logging.info('Applying attenuation=%r', attenuation_db) |
| self.context.attenuator.set_variable_attenuation_on_port( |
| port, attenuation_db) |
| if attenuation_db >= (site_attenuator.Attenuator. |
| MAX_VARIABLE_ATTENUATION): |
| logging.warning('. NOTICE: Attenuation is at maximum value') |
| keep_tweaking_snr = False |
| elif system_measures_noise: |
| actual_snr_db = self.get_signal_to_noise(frequency) |
| if actual_snr_db > target_snr_db: |
| logging.info('. S/N (%d) > target value (%d)', |
| actual_snr_db, target_snr_db) |
| attenuation_db += actual_snr_db - target_snr_db |
| else: |
| logging.info('. GOOD S/N=%r', actual_snr_db) |
| keep_tweaking_snr = False |
| else: |
| actual_signal_dbm = self.context.client.wifi_signal_level |
| logging.info('. signal=%r', actual_signal_dbm) |
| if actual_signal_dbm > target_signal_dbm: |
| logging.info('. Signal > target value (%d)', |
| target_signal_dbm) |
| attenuation_db += actual_signal_dbm - target_signal_dbm |
| else: |
| keep_tweaking_snr = False |
| |
| logging.info('Done') |
| |
| |
| def get_signal_to_noise(self, frequency): |
| """Gets both the signal and the noise on the current connection. |
| |
| @param frequency: noise needs to be read for a frequency. |
| @returns: signal and noise in dBm |
| |
| """ |
| ping_ip = self.context.get_wifi_addr(ap_num=0) |
| ping_config = ping_runner.PingConfig(target_ip=ping_ip, count=1, |
| ignore_status=True, |
| ignore_result=True) |
| self.context.client.ping(ping_config) # Just to provide traffic. |
| signal_dbm = self.context.client.wifi_signal_level |
| noise_dbm = self.context.client.wifi_noise_level(frequency) |
| print '. signal: %r, noise: %r' % (signal_dbm, noise_dbm) |
| if noise_dbm is None: |
| return None |
| return signal_dbm - noise_dbm |
