# 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 copy
import logging

from autotest_lib.client.common_lib import error
from autotest_lib.client.common_lib.cros.network import xmlrpc_security_types


class HostapConfig(object):
    """Parameters for router configuration."""

    # A mapping of frequency to channel number.  This includes some
    # frequencies used outside the US.
    CHANNEL_MAP = {2412: 1,
                   2417: 2,
                   2422: 3,
                   2427: 4,
                   2432: 5,
                   2437: 6,
                   2442: 7,
                   2447: 8,
                   2452: 9,
                   2457: 10,
                   2462: 11,
                   # 12, 13 are only legitimate outside the US.
                   2467: 12,
                   2472: 13,
                   # 34 valid in Japan.
                   5170: 34,
                   # 36-116 valid in the US, except 38, 42, and 46, which have
                   # mixed international support.
                   5180: 36,
                   5190: 38,
                   5200: 40,
                   5210: 42,
                   5220: 44,
                   5230: 46,
                   5240: 48,
                   5260: 52,
                   5280: 56,
                   5300: 60,
                   5320: 64,
                   5500: 100,
                   5520: 104,
                   5540: 108,
                   5560: 112,
                   5580: 116,
                   # 120, 124, 128 valid in Europe/Japan.
                   5600: 120,
                   5620: 124,
                   5640: 128,
                   # 132+ valid in US.
                   5660: 132,
                   5680: 136,
                   5700: 140,
                   5745: 149,
                   5765: 153,
                   5785: 157,
                   5805: 161,
                   5825: 165}

    MODE_11A = 'a'
    MODE_11B = 'b'
    MODE_11G = 'g'
    MODE_11N_MIXED = 'n-mixed'
    MODE_11N_PURE = 'n-only'

    N_CAPABILITY_HT20 = object()
    N_CAPABILITY_HT40 = object()
    N_CAPABILITY_HT40_PLUS = object()
    N_CAPABILITY_HT40_MINUS = object()
    N_CAPABILITY_GREENFIELD = object()
    N_CAPABILITY_SGI20 = object()
    N_CAPABILITY_SGI40 = object()
    ALL_N_CAPABILITIES = [N_CAPABILITY_HT20,
                          N_CAPABILITY_HT40,
                          N_CAPABILITY_HT40_PLUS,
                          N_CAPABILITY_HT40_MINUS,
                          N_CAPABILITY_GREENFIELD,
                          N_CAPABILITY_SGI20,
                          N_CAPABILITY_SGI40]

    # This is a loose merging of the rules for US and EU regulatory
    # domains as taken from IEEE Std 802.11-2012 Appendix E.  For instance,
    # we tolerate HT40 in channels 149-161 (not allowed in EU), but also
    # tolerate HT40+ on channel 7 (not allowed in the US).  We take the loose
    # definition so that we don't prohibit testing in either domain.
    HT40_ALLOW_MAP = {N_CAPABILITY_HT40_MINUS: range(6, 14) +
                                               range(40, 65, 8) +
                                               range(104, 137, 8) +
                                               [153, 161],
                      N_CAPABILITY_HT40_PLUS: range(1, 8) +
                                              range(36, 61, 8) +
                                              range(100, 133, 8) +
                                              [149, 157]}

    PMF_SUPPORT_DISABLED = 0
    PMF_SUPPORT_ENABLED = 1
    PMF_SUPPORT_REQUIRED = 2
    PMF_SUPPORT_VALUES = (PMF_SUPPORT_DISABLED,
                          PMF_SUPPORT_ENABLED,
                          PMF_SUPPORT_REQUIRED)


    @staticmethod
    def get_channel_for_frequency(frequency):
        """Returns the channel number associated with a given frequency.

        @param value: int frequency in MHz.

        @return int frequency associated with the channel.

        """
        return HostapConfig.CHANNEL_MAP[frequency]


    @staticmethod
    def get_frequency_for_channel(channel):
        """Returns the frequency associated with a given channel number.

        @param value: int channel number.

        @return int frequency in MHz associated with the channel.

        """
        for frequency, channel_iter in HostapConfig.CHANNEL_MAP.iteritems():
            if channel == channel_iter:
                return frequency
        else:
            raise error.TestFail('Unknown channel value: %r.' % channel)


    @property
    def channel(self):
        """@return int channel number for self.frequency."""
        return self.get_channel_for_frequency(self.frequency)


    @channel.setter
    def channel(self, value):
        """Sets the channel number to configure hostapd to listen on.

        @param value: int channel number.

        """
        self.frequency = self.get_frequency_for_channel(value)


    @property
    def frequency(self):
        """@return int frequency for hostapd to listen on."""
        return self._frequency


    @frequency.setter
    def frequency(self, value):
        """Sets the frequency for hostapd to listen on.

        @param value: int frequency in MHz.

        """
        if value not in self.CHANNEL_MAP or not self.supports_frequency(value):
            raise error.TestFail('Tried to set an invalid frequency: %r.' %
                                 value)

        self._frequency = value


    @property
    def hostapd_ht_capabilities(self):
        """@return string suitable for the ht_capab= line in a hostapd config"""
        ret = []
        if self.ht40_plus_allowed:
            ret.append('[HT40+]')
        elif self.ht40_minus_allowed:
            ret.append('[HT40-]')
        if self.N_CAPABILITY_GREENFIELD in self._n_capabilities:
            logging.warning('Greenfield flag is ignored for hostap...')
        if self.N_CAPABILITY_SGI20 in self._n_capabilities:
            ret.append('[SHORT-GI-20]')
        if self.N_CAPABILITY_SGI40 in self._n_capabilities:
            ret.append('[SHORT-GI-40]')
        return ''.join(ret)


    @property
    def ht40_plus_allowed(self):
        """@return True iff HT40+ is enabled for this configuration."""
        channel_supported = (self.channel in
                             self.HT40_ALLOW_MAP[self.N_CAPABILITY_HT40_PLUS])
        return ((self.N_CAPABILITY_HT40_PLUS in self._n_capabilities or
                 self.N_CAPABILITY_HT40 in self._n_capabilities) and
                channel_supported)


    @property
    def ht40_minus_allowed(self):
        """@return True iff HT40- is enabled for this configuration."""
        channel_supported = (self.channel in
                             self.HT40_ALLOW_MAP[self.N_CAPABILITY_HT40_MINUS])
        return ((self.N_CAPABILITY_HT40_MINUS in self._n_capabilities or
                 self.N_CAPABILITY_HT40 in self._n_capabilities) and
                channel_supported)


    @property
    def ht_packet_capture_mode(self):
        """Get an appropriate packet capture HT parameter.

        When we go to configure a raw monitor we need to configure
        the phy to listen on the correct channel.  Part of doing
        so is to specify the channel width for HT channels.  In the
        case that the AP is configured to be either HT40+ or HT40-,
        we could return the wrong parameter because we don't know which
        configuration will be chosen by hostap.

        @return string HT parameter for frequency configuration.

        """
        if not self.is_11n:
            return None

        if self.ht40_plus_allowed:
            return 'HT40+'

        if self.ht40_minus_allowed:
            return 'HT40-'

        return 'HT20'


    @property
    def hw_mode(self):
        """@return string hardware mode understood by hostapd."""
        if self._mode == self.MODE_11A:
            return self.MODE_11A
        if self._mode == self.MODE_11B:
            return self.MODE_11B
        if self._mode == self.MODE_11G:
            return self.MODE_11G
        if self._mode in (self.MODE_11N_MIXED, self.MODE_11N_PURE):
            # For their own historical reasons, hostapd wants it this way.
            if self.frequency > 5000:
                return self.MODE_11A

            return self.MODE_11G

        raise error.TestFail('Invalid mode.')


    @property
    def is_11n(self):
        """@return True iff we're trying to host an 802.11n network."""
        return self._mode in (self.MODE_11N_MIXED, self.MODE_11N_PURE)


    @property
    def printable_mode(self):
        """@return human readable mode string."""
        if self.is_11n:
            return self.ht_packet_capture_mode

        return '11' + self.hw_mode.upper()


    @property
    def require_ht(self):
        """@return True iff clients should be required to support HT."""
        # TODO(wiley) Why? (crbug.com/237370)
        logging.warning('Not enforcing pure N mode because Snow does '
                        'not seem to support it...')
        return False


    @property
    def ssid_suffix(self):
        """@return meaningful suffix for SSID."""
        return '_ch%d' % self.channel


    def __init__(self, mode=MODE_11B, channel=None, frequency=None,
                 n_capabilities=[], hide_ssid=None, beacon_interval=None,
                 dtim_period=None, frag_threshold=None, ssid=None, bssid=None,
                 force_wmm=None, security_config=None,
                 pmf_support=PMF_SUPPORT_DISABLED,
                 obss_interval=None):
        """Construct a HostapConfig.

        You may specify channel or frequency, but not both.  Both options
        are checked for validity (i.e. you can't specify an invalid channel
        or a frequency that will not be accepted).

        @param mode string MODE_11x defined above.
        @param channel int channel number.
        @param frequency int frequency of channel.
        @param n_capabilities list of N_CAPABILITY_x defined above.
        @param hide_ssid True if we should set up a hidden SSID.
        @param beacon_interval int beacon interval of AP.
        @param dtim_period int include a DTIM every |dtim_period| beacons.
        @param frag_threshold int maximum outgoing data frame size.
        @param ssid string up to 32 byte SSID overriding the router default.
        @param bssid string like 00:11:22:33:44:55.
        @param force_wmm True if we should force WMM on, False if we should
            force it off, None if we shouldn't force anything.
        @param security_config SecurityConfig object.
        @param pmf_support one of PMF_SUPPORT_* above.  Controls whether the
            client supports/must support 802.11w.
        @param obss_interval int interval in seconds that client should be
            required to do background scans for overlapping BSSes.

        """
        super(HostapConfig, self).__init__()
        if channel is not None and frequency is not None:
            raise error.TestError('Specify either frequency or channel '
                                  'but not both.')

        self.wmm_enabled = False
        unknown_caps = [cap for cap in n_capabilities
                        if cap not in self.ALL_N_CAPABILITIES]
        if unknown_caps:
            raise error.TestError('Unknown capabilities: %r' % unknown_caps)

        self._n_capabilities = set(n_capabilities)
        if self._n_capabilities:
            self.wmm_enabled = True
        if self._n_capabilities and mode is None:
            mode = self.MODE_11N_PURE
        self._mode = mode

        self._frequency = None
        if channel:
            self.channel = channel
        elif frequency:
            self.frequency = frequency
        else:
            raise error.TestError('Specify either frequency or channel.')

        if not self.supports_frequency(self.frequency):
            raise error.TestFail('Configured a mode %s that does not support '
                                 'frequency %d' % (self._mode, self.frequency))

        self.hide_ssid = hide_ssid
        self.beacon_interval = beacon_interval
        self.dtim_period = dtim_period
        self.frag_threshold = frag_threshold
        if ssid and len(ssid) > 32:
            raise error.TestFail('Tried to specify SSID that was too long.')

        self.ssid = ssid
        self.bssid = bssid
        if force_wmm is not None:
            self.wmm_enabled = force_wmm
        if pmf_support not in self.PMF_SUPPORT_VALUES:
            raise error.TestFail('Invalid value for pmf_support: %r' %
                                 pmf_support)

        self.pmf_support = pmf_support
        self.security_config = (copy.copy(security_config) or
                                xmlrpc_security_types.SecurityConfig())
        self.obss_interval = obss_interval


    def __repr__(self):
        return ('%s(mode=%r, channel=%r, frequency=%r, '
                'n_capabilities=%r, hide_ssid=%r, beacon_interval=%r, '
                'dtim_period=%r, frag_threshold=%r, ssid=%r, bssid=%r, '
                'wmm_enabled=%r, security_config=%r)' % (
                        self.__class__.__name__,
                        self._mode,
                        self.channel,
                        self.frequency,
                        self._n_capabilities,
                        self.hide_ssid,
                        self.beacon_interval,
                        self.dtim_period,
                        self.frag_threshold,
                        self.ssid,
                        self.bssid,
                        self.wmm_enabled,
                        self.security_config))


    def get_security_hostapd_conf(self):
        """@return dict of hostapd settings related to security."""
        return self.security_config.get_hostapd_config()


    def supports_channel(self, value):
        """Check whether channel is supported by the current hardware mode.

        @param value: int channel to check.
        @return True iff the current mode supports the band of the channel.

        """
        for freq, channel in self.CHANNEL_MAP.iteritems():
            if channel == value:
                return self.supports_frequency(freq)

        return False


    def supports_frequency(self, frequency):
        """Check whether frequency is supported by the current hardware mode.

        @param frequency: int frequency to check.
        @return True iff the current mode supports the band of the frequency.

        """
        if self._mode == self.MODE_11A and frequency < 5000:
            return False

        if self._mode in (self.MODE_11B, self.MODE_11G) and frequency > 5000:
            return False

        if frequency not in self.CHANNEL_MAP:
            return False

        channel = self.CHANNEL_MAP[frequency]
        supports_plus = (channel in
                         self.HT40_ALLOW_MAP[self.N_CAPABILITY_HT40_PLUS])
        supports_minus = (channel in
                          self.HT40_ALLOW_MAP[self.N_CAPABILITY_HT40_MINUS])
        if (self.N_CAPABILITY_HT40_PLUS in self._n_capabilities and
                not supports_plus):
            return False

        if (self.N_CAPABILITY_HT40_MINUS in self._n_capabilities and
                not supports_minus):
            return False

        if (self.N_CAPABILITY_HT40 in self._n_capabilities and
                not supports_plus and not supports_minus):
            return False

        return True