# Copyright (c) 2011 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 re

from autotest_lib.client.common_lib import error
from autotest_lib.server.cros.network import packet_capturer

class LinuxSystem(object):
    """Superclass for test machines running Linux.

    Provides a common point for routines that use the cfg80211 userspace tools
    to manipulate the wireless stack, regardless of the role they play.
    Currently the commands shared are the init, which queries for wireless
    devices, along with start_capture and stop_capture.  More commands may
    migrate from site_linux_router as appropriate to share.

    """

    CAPABILITY_5GHZ = '5ghz'
    CAPABILITY_MULTI_AP = 'multi_ap'
    CAPABILITY_MULTI_AP_SAME_BAND = 'multi_ap_same_band'
    CAPABILITY_IBSS = 'ibss_supported'
    CAPABILITY_SEND_MANAGEMENT_FRAME = 'send_management_frame'


    @property
    def capabilities(self):
        """@return iterable object of AP capabilities for this system."""
        if self._capabilities is None:
            self._capabilities = self.get_capabilities()
            logging.info('%s system capabilities: %r',
                         self.role, self._capabilities)
        return self._capabilities


    def __init__(self, host, params, role):
        # Command locations.
        self.cmd_iw = params.get('cmd_iw', '/usr/sbin/iw')
        self.cmd_ip = params.get('cmd_ip', '/usr/sbin/ip')
        self.cmd_dhcpd = params.get('cmd_dhcpd', '/usr/sbin/dhcpd')
        self.cmd_readlink = params.get('cmd_readlink', '/bin/ls -l')
        self.cmd_tcpdump = params.get('cmd_tcpdump', '/usr/sbin/tcpdump')

        self.phy_bus_preference = params.get('phy_bus_preference', {})
        self.phydev2 = params.get('phydev2', None)
        self.phydev5 = params.get('phydev5', None)

        self.host = host
        self.role = role

        self.capture_channel = None
        self.capture_ht_type = None
        self._packet_capturer = packet_capturer.PacketCapturer(
                self.host, host_description=role, cmd_ip=self.cmd_ip,
                cmd_iw=self.cmd_iw, cmd_netdump=self.cmd_tcpdump)

        self.phys_for_frequency, self.phy_bus_type = self._get_phy_info()
        self.wlanifs_in_use = []
        self._capabilities = None


    def _get_phy_info(self):
        """Get information about WiFi devices.

        Parse the output of 'iw list' and some of sysfs and return:

        A dict |phys_for_frequency| which maps from each frequency to a
        list of phys that support that channel.

        A dict |phy_bus_type| which maps from each phy to the bus type for
        each phy.

        @return phys_for_frequency, phy_bus_type tuple as described.

        """
        output = self.host.run('%s list' % self.cmd_iw).stdout
        re_wiphy = re.compile('Wiphy (.*)')
        re_mhz = re.compile('(\d+) MHz')
        in_phy = False
        phy_list = []
        phys_for_frequency = {}
        for line in output.splitlines():
            match_wiphy = re_wiphy.match(line)
            if match_wiphy:
                in_phy = True
                wiphyname = match_wiphy.group(1)
                phy_list.append(wiphyname)
            elif in_phy:
                if line[0] == '\t':
                    match_mhz = re_mhz.search(line)
                    if match_mhz:
                        mhz = int(match_mhz.group(1))
                        if mhz not in phys_for_frequency:
                            phys_for_frequency[mhz] = [wiphyname]
                        else:
                            phys_for_frequency[mhz].append(wiphyname)
                else:
                    in_phy = False

        phy_bus_type = {}
        for phy in phy_list:
            phybus = 'unknown'
            command = '%s /sys/class/ieee80211/%s' % (self.cmd_readlink, phy)
            devpath = self.host.run(command).stdout
            if '/usb' in devpath:
                phybus = 'usb'
            elif '/mmc' in devpath:
                phybus = 'sdio'
            elif '/pci' in devpath:
                phybus = 'pci'
            phy_bus_type[phy] = phybus
        logging.debug('Got phys for frequency: %r', phys_for_frequency)
        return phys_for_frequency, phy_bus_type


    def _remove_interface(self, interface, remove_monitor):
        """Remove an interface from a WiFi device.

        @param interface string interface to remove (e.g. wlan0).
        @param remove_monitor bool True if we should also remove a monitor.

        """
        self.host.run('%s link set %s down' % (self.cmd_ip, interface))
        self.host.run('%s dev %s del' % (self.cmd_iw, interface))
        if remove_monitor:
            # Some old hostap implementations create a 'mon.<interface>' to
            # handle management frame transmit/receive.
            self.host.run('%s link set mon.%s down' % (self.cmd_ip, interface),
                          ignore_status=True)
            self.host.run('%s dev mon.%s del' % (self.cmd_iw, interface),
                      ignore_status=True)
        for phytype in self.wlanifs:
            for phy in self.wlanifs[phytype]:
                if self.wlanifs[phytype][phy] == interface:
                    self.wlanifs[phytype].pop(phy)
                    break


    def _remove_interfaces(self):
        """Remove all WiFi devices."""
        self.wlanifs = {}
        # Remove all wifi devices.
        output = self.host.run('%s dev' % self.cmd_iw).stdout
        test = re.compile('[\s]*Interface (.*)')
        for line in output.splitlines():
            m = test.match(line)
            if m:
                self._remove_interface(m.group(1), False)


    def get_capabilities(self):
        caps = set()
        phymap = self.phys_for_frequency
        if [freq for freq in phymap.iterkeys() if freq > 5000]:
            # The frequencies are expressed in megaherz
            caps.add(self.CAPABILITY_5GHZ)
        if [freq for freq in phymap.iterkeys() if len(phymap[freq]) > 1]:
            caps.add(self.CAPABILITY_MULTI_AP_SAME_BAND)
            caps.add(self.CAPABILITY_MULTI_AP)
        elif len(self.phy_bus_type) > 1:
            caps.add(self.CAPABILITY_MULTI_AP)
        return caps


    def start_capture_params(self, params):
        """Start a packet capture.

        Note that in |params|, 'channel' refers to the frequency of the WiFi
        channel (e.g. 2412), not the channel number.

        @param params dict of site_wifitest parameters.

        """
        if 'channel' in params:
            self.capture_channel = int(params['channel'])
        for arg in ('ht20', 'ht40+', 'ht40-'):
            if arg in params:
                self.capture_ht_type = arg.upper()

        if not self.capture_channel:
            raise error.TestError('No capture channel specified.')

        self.start_capture(self.capture_channel, ht_type=self.capture_ht_type)


    def stop_capture_params(self, params):
        """Stop a packet capture.

        @param params dict unused, but required by our dispatch method.

        """
        self.stop_capture()


    def start_capture(self, frequency, ht_type=None):
        """Start a packet capture.

        @param frequency int frequency of channel to capture on.
        @param ht_type string one of (None, 'HT20', 'HT40+', 'HT40-').

        """
        if self._packet_capturer.capture_running:
            self.stop_capture()
        # LinuxSystem likes to manage the phys on its own, so let it.
        self.capture_interface = self._get_wlanif(frequency, 'monitor')
        # But let the capturer configure the interface.
        self._packet_capturer.configure_raw_monitor(self.capture_interface,
                                                    frequency,
                                                    ht_type=ht_type)
        # Start the capture.
        self._packet_capturer.start_capture(self.capture_interface, './debug/')


    def stop_capture(self):
        """Stop a packet capture."""
        if not self._packet_capturer.capture_running:
            return
        self._packet_capturer.stop_capture()
        self.host.run('%s link set %s down' % (self.cmd_ip,
                                               self.capture_interface))
        self._release_wlanif(self.capture_interface)


    def _get_phy_for_frequency(self, frequency, phytype):
        """Get a phy appropriate for a frequency and phytype.

        Return the most appropriate phy interface for operating on the
        frequency |frequency| in the role indicated by |phytype|.  Prefer idle
        phys to busy phys if any exist.  Secondarily, show affinity for phys
        that use the bus type associated with this phy type.

        @param frequency int WiFi frequency of phy.
        @param phytype string key of phytype registered at construction time.
        @return string name of phy to use.

        """
        phys = self.phys_for_frequency[frequency]

        busy_phys = set(phy for phy, wlanif, phytype in self.wlanifs_in_use)
        idle_phys = [phy for phy in phys if phy not in busy_phys]
        phys = idle_phys or phys

        preferred_bus = self.phy_bus_preference.get(phytype)
        preferred_phys = [phy for phy in phys
                          if self.phy_bus_type[phy] == preferred_bus]
        phys = preferred_phys or phys

        return phys[0]


    def _get_wlanif(self, frequency, phytype, mode = None, same_phy_as = None):
        """Get a WiFi device that supports the given frequency, mode, and type.

        This function is used by inherited classes, so we use the single '_'
        convention rather than the '__' we usually use for non-scriptable
        commands, since these cannot be inherited by subclasses.

        We still support the old "phydevN" parameters, but this code is
        smart enough to do without it.

        @param frequency int WiFi frequency to support.
        @param phytype string type of phy (e.g. 'monitor').
        @param mode string 'a' 'b' or 'g'.
        @param same_phy_as string create the interface on the same phy as this.
        @return string WiFi device.

        """
        if same_phy_as:
            for phy, wlanif_i, phytype_i in self.wlanifs_in_use:
                if wlanif_i == same_phy_as:
                     break
            else:
                raise error.TestFail('Unable to find phy for interface %s' %
                                     same_phy_as)
        elif mode in ('b', 'g') and self.phydev2 is not None:
            phy = self.phydev2
        elif mode == 'a' and self.phydev5 is not None:
            phy = self.phydev5
        elif frequency in self.phys_for_frequency:
            phy = self._get_phy_for_frequency(frequency, phytype)
        else:
            raise error.TestFail('Unable to find phy for frequency %d mode %s' %
                                 (frequency, mode))

        # If self.wlanifs is not defined, this is the first time we've
        # allocated a wlan interface.  Perform init by calling
        # remove_interfaces().
        if not hasattr(self, 'wlanifs'):
            self._remove_interfaces()
        if phytype not in self.wlanifs:
            self.wlanifs[phytype] = {}
        elif phy in self.wlanifs[phytype]:
            return self.wlanifs[phytype][phy]

        wlanif = '%s%d' % (phytype, len(self.wlanifs[phytype].keys()))
        self.wlanifs[phytype][phy] = wlanif

        self.host.run('%s phy %s interface add %s type %s' %
            (self.cmd_iw, phy, wlanif, phytype))

        self.wlanifs_in_use.append((phy, wlanif, phytype))

        return wlanif


    def _release_wlanif(self, wlanif):
        """Release a device allocated throuhg _get_wlanif().

        @param wlanif string name of device to release.

        """
        for phy, wlanif_i, phytype in self.wlanifs_in_use:
            if wlanif_i == wlanif:
                 self.wlanifs_in_use.remove((phy, wlanif, phytype))


    def require_capabilities(self, requirements, fatal_failure=False):
        """Require capabilities of this LinuxSystem.

        Check that capabilities in |requirements| exist on this system.
        Raise and exception to skip but not fail the test if said
        capabilities are not found.  Pass |fatal_failure| to cause this
        error to become a test failure.

        @param requirements list of CAPABILITY_* defined above.
        @param fatal_failure bool True iff failures should be fatal.

        """
        to_be_raised = error.TestNAError
        if fatal_failure:
            to_be_raised = error.TestFail
        missing = [cap for cap in requirements if not cap in self.capabilities]
        if missing:
            raise to_be_raised('AP on %s is missing required capabilites: %r' %
                               (self.role, missing))