python3-pyghmi 1.0.32-4 / usr / lib / python3 / dist-packages / pyghmi / ipmi / sdr.py

# vim: tabstop=4 shiftwidth=4 softtabstop=4
# coding=utf8

# Copyright 2014 IBM Corporation
# Copyright 2015 Lenovo
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

# This module provides access to SDR offered by a BMC
# This data is common between 'sensors' and 'inventory' modules since SDR
# is both used to enumerate sensors for sensor commands and FRU ids for FRU
# commands

# For now, we will not offer persistent SDR caching as we do in xCAT's IPMI
# code.  Will see if it is adequate to advocate for high object reuse in a
# persistent process for the moment.

# Focus is at least initially on the aspects that make the most sense for a
# remote client to care about.  For example, smbus information is being
# skipped for now

import math
import pyghmi.constants as const
import pyghmi.exceptions as exc
import pyghmi.ipmi.private.constants as ipmiconst
import struct
import weakref

TYPE_UNKNOWN = 0
TYPE_SENSOR = 1
TYPE_FRU = 2


def ones_complement(value, bits):
    # utility function to help with the large amount of 2s
    # complement prevalent in ipmi spec
    signbit = 0b1 << (bits - 1)
    if value & signbit:
        # if negative, subtract 1, then take 1s
        # complement given bits width
        return 0 - (value ^ ((0b1 << bits) - 1))
    else:
        return value


def twos_complement(value, bits):
    # utility function to help with the large amount of 2s
    # complement prevalent in ipmi spec
    signbit = 0b1 << (bits - 1)
    if value & signbit:
        # if negative, subtract 1, then take 1s
        # complement given bits width
        return 0 - ((value - 1) ^ ((0b1 << bits) - 1))
    else:
        return value


unit_types = {
    # table 43-15 'sensor unit type codes'
    0: '',
    1: '°C',
    2: '°F',
    3: 'K',
    4: 'V',
    5: 'A',
    6: 'W',
    7: 'J',
    8: 'C',
    9: 'VA',
    10: 'nt',
    11: 'lm',
    12: 'lx',
    13: 'cd',
    14: 'kPa',
    15: 'PSI',
    16: 'N',
    17: 'CFM',
    18: 'RPM',
    19: 'Hz',
    20: 'μs',
    21: 'ms',
    22: 's',
    23: 'min',
    24: 'hr',
    25: 'd',
    26: 'week(s)',
    27: 'mil',
    28: 'inches',
    29: 'ft',
    30: 'cu in',
    31: 'cu feet',
    32: 'mm',
    33: 'cm',
    34: 'm',
    35: 'cu cm',
    36: 'cu m',
    37: 'L',
    38: 'fl. oz.',
    39: 'radians',
    40: 'steradians',
    41: 'revolutions',
    42: 'cycles',
    43: 'g',
    44: 'ounce',
    45: 'lb',
    46: 'ft-lb',
    47: 'oz-in',
    48: 'gauss',
    49: 'gilberts',
    50: 'henry',
    51: 'millihenry',
    52: 'farad',
    53: 'microfarad',
    54: 'ohms',
    55: 'siemens',
    56: 'mole',
    57: 'becquerel',
    58: 'ppm',
    60: 'dB',
    61: 'dBA',
    62: 'dBC',
    63: 'Gy',
    64: 'sievert',
    65: 'color temp deg K',
    66: 'bit',
    67: 'kb',
    68: 'mb',
    69: 'gb',
    70: 'byte',
    71: 'kB',
    72: 'mB',
    73: 'gB',
    74: 'word',
    75: 'dword',
    76: 'qword',
    77: 'line',
    78: 'hit',
    79: 'miss',
    80: 'retry',
    81: 'reset',
    82: 'overrun/overflow',
    83: 'underrun',
    84: 'collision',
    85: 'packets',
    86: 'messages',
    87: 'characters',
    88: 'error',
    89: 'uncorrectable error',
    90: 'correctable error',
    91: 'fatal error',
    92: 'grams',
}

sensor_rates = {
    0: '',
    1: ' per us',
    2: ' per ms',
    3: ' per s',
    4: ' per minute',
    5: ' per hour',
    6: ' per day',
}


class SensorReading(object):
    """Representation of the state of a sensor.

    It is initialized by pyghmi internally, it does not make sense for
    a developer to create one of these objects directly.

    It provides the following properties:
    name: UTF-8 string describing the sensor
    units: UTF-8 string describing the units of the sensor (if numeric)
    value: Value of the sensor if numeric
    imprecision: The amount by which the actual measured value may deviate from
        'value' due to limitations in the resolution of the given sensor.
    """

    def __init__(self, reading, suffix):
        self.broken_sensor_ids = {}
        self.health = const.Health.Ok
        self.type = reading['type']
        self.value = None
        self.imprecision = None
        self.states = []
        self.state_ids = []
        self.unavailable = 0
        try:
            self.health = reading['health']
            self.states = reading['states']
            self.state_ids = reading['state_ids']
            self.value = reading['value']
            self.imprecision = reading['imprecision']
        except KeyError:
            pass
        if 'unavailable' in reading:
            self.unavailable = 1
        self.units = suffix
        self.name = reading['name']

    def __repr__(self):
        return repr({
            'value': self.value,
            'states': self.states,
            'state_ids': self.state_ids,
            'units': self.units,
            'imprecision': self.imprecision,
            'name': self.name,
            'type': self.type,
            'unavailable': self.unavailable,
            'health': self.health
        })

    def simplestring(self):
        """Return a summary string of the reading.

        This is intended as a sampling of how the data could be presented by
        a UI.  It's intended to help a developer understand the relation
        between the attributes of a sensor reading if it is not quite clear
        """
        repr = self.name + ": "
        if self.value is not None:
            repr += str(self.value)
            repr += " ± " + str(self.imprecision)
            repr += self.units
        for state in self.states:
            repr += state + ","
        if self.health >= const.Health.Failed:
            repr += '(Failed)'
        elif self.health >= const.Health.Critical:
            repr += '(Critical)'
        elif self.health >= const.Health.Warning:
            repr += '(Warning)'
        return repr


class SDREntry(object):
    """Represent a single entry in the IPMI SDR.

    This is created and consumed by pyghmi internally, there is no reason for
    external code to pay attention to this class.
    """

    def __init__(self, entrybytes, ipmicmd, reportunsupported=False):
        # ignore record id for now, we only care about the sensor number for
        # moment
        self.readable = True
        self.reportunsupported = reportunsupported
        self.ipmicmd = ipmicmd
        if entrybytes[2] != 0x51:
            # only recognize '1.5', the only version defined at time of writing
            raise NotImplementedError
        self.rectype = entrybytes[3]
        self.linearization = None
        # most important to get going are 1, 2, and 11
        self.sdrtype = TYPE_SENSOR  # assume a sensor
        if self.rectype == 1:  # full sdr
            self.full_decode(entrybytes[5:])
        elif self.rectype == 2:  # full sdr
            self.compact_decode(entrybytes[5:])
        elif self.rectype == 3:  # event only
            self.eventonly_decode(entrybytes[5:])
        elif self.rectype == 8:  # entity association
            self.association_decode(entrybytes[5:])
        elif self.rectype == 0x11:  # FRU locator
            self.fru_decode(entrybytes[5:])
        elif self.rectype == 0x12:  # Management controller
            self.mclocate_decode(entrybytes[5:])
        elif self.rectype == 0xc0:  # OEM format
            self.sdrtype = TYPE_UNKNOWN   # assume undefined
            self.oem_decode(entrybytes[5:])
        elif self.reportunsupported:
            raise NotImplementedError
        else:
            self.sdrtype = TYPE_UNKNOWN

    @property
    def name(self):
        if self.sdrtype == TYPE_SENSOR:
            return self.sensor_name
        elif self.sdrtype == TYPE_FRU:
            return self.fru_name
        else:
            return "UNKNOWN"

    def oem_decode(self, entry):
        mfgid = entry[0] + (entry[1] << 8) + (entry[2] << 16)
        if self.reportunsupported:
            raise NotImplementedError("No support for mfgid %X" % mfgid)

    def mclocate_decode(self, entry):
        # For now, we don't have use for MC locator records
        # we'll ignore them at the moment
        self.sdrtype = TYPE_UNKNOWN
        pass

    def fru_decode(self, entry):
        # table 43-7 FRU Device Locator
        self.sdrtype = TYPE_FRU
        self.fru_name = self.tlv_decode(entry[10], entry[11:])
        self.fru_number = entry[1]
        self.fru_logical = (entry[2] & 0b10000000) == 0b10000000
        # 0x8  to 0x10..  0 unspecified except on 0x10, 1 is dimm
        self.fru_type_and_modifier = (entry[5] << 8) + entry[6]

    def association_decode(self, entry):
        # table 43-4 Entity Associaition Record
        # TODO(jbjohnso): actually represent this data
        self.sdrtype = TYPE_UNKNOWN

    def eventonly_decode(self, entry):
        # table 43-3 event_only sensor record
        self._common_decode(entry)
        self.sensor_name = self.tlv_decode(entry[11], entry[12:])
        self.readable = False

    def compact_decode(self, entry):
        # table 43-2 compact sensor record
        self._common_decode(entry)
        self.sensor_name = self.tlv_decode(entry[26], entry[27:])

    def assert_trap_value(self, offset):
        trapval = (self.sensor_type_number << 16) + (self.reading_type << 8)
        return trapval + offset

    def _common_decode(self, entry):
        # event only, compact and full are very similar
        # this function handles the common aspects of compact and full
        # offsets from spec, minus 6
        self.sensor_number = entry[2]
        self.entity = ipmiconst.entity_ids.get(
            entry[3], 'Unknown entity {0}'.format(entry[3]))
        if self.rectype == 3:
            self.sensor_type_number = entry[5]
            self.reading_type = entry[6]  # table 42-1
        else:
            self.sensor_type_number = entry[7]
            self.reading_type = entry[8]  # table 42-1
        try:
            self.sensor_type = ipmiconst.sensor_type_codes[
                self.sensor_type_number]
        except KeyError:
            self.sensor_type = "UNKNOWN type " + str(self.sensor_type_number)
        if self.rectype == 3:
            return
        # 0: unspecified
        # 1: generic threshold based
        # 0x6f: discrete sensor-specific from table 42-3, sensor offsets
        # all others per table 42-2, generic discrete
        # numeric format is one of:
        # 0 - unsigned, 1 - 1s complement, 2 - 2s complement, 3 - ignore number
        # compact records are supposed to always write it as '3', presumably
        # to allow for the concept of a compact record with a numeric format
        # even though numerics are not allowed today.  Some implementations
        # violate the spec and do something other than 3 today.  Tolerate
        # the violation under the assumption that things are not so hard up
        # that there will ever be a need for compact sensors supporting numeric
        # values
        if self.rectype == 2:
            self.numeric_format = 3
        else:
            self.numeric_format = (entry[15] & 0b11000000) >> 6
        self.sensor_rate = sensor_rates[(entry[15] & 0b111000) >> 3]
        self.unit_mod = ""
        if (entry[15] & 0b110) == 0b10:  # unit1 by unit2
            self.unit_mod = "/"
        elif (entry[15] & 0b110) == 0b100:
            # combine the units by multiplying, SI nomenclature is either spac
            # or hyphen, so go with space
            self.unit_mod = " "
        self.percent = ''
        if entry[15] & 1 == 1:
            self.percent = '% '
        self.baseunit = unit_types[entry[16]]
        self.modunit = unit_types[entry[17]]
        self.unit_suffix = self.percent + self.baseunit + self.unit_mod + \
            self.modunit

    def full_decode(self, entry):
        # offsets are table from spec, minus 6
        # TODO(jbjohnso): table 43-13, put in constants to interpret entry[3]
        self._common_decode(entry)
        # now must extract the formula data to transform values
        # entry[18 to entry[24].
        # if not linear, must use get sensor reading factors
        # TODO(jbjohnso): the various other values
        self.sensor_name = self.tlv_decode(entry[42], entry[43:])
        self.linearization = entry[18] & 0b1111111
        if self.linearization <= 11:
            # the enumuration of linear sensors goes to 11,
            # static formula parameters are applicable, decode them
            # if 0x70, then the sesor reading will have to get the
            # factors on the fly.
            # the formula could apply if we bother with nominal
            # reading interpretation
            self.decode_formula(entry[19:25])

    def _decode_state(self, state):
        mapping = ipmiconst.generic_type_offsets
        try:
            if self.reading_type in mapping:
                desc = mapping[self.reading_type][state]['desc']
                health = mapping[self.reading_type][state]['severity']
            elif self.reading_type == 0x6f:
                mapping = ipmiconst.sensor_type_offsets
                desc = mapping[self.sensor_type_number][state]['desc']
                health = mapping[self.sensor_type_number][state]['severity']
            else:
                desc = "Unknown state %d" % state
                health = const.Health.Warning
        except KeyError:
            desc = "Unknown state %d for reading type %d/sensor type %d" % (
                state, self.reading_type, self.sensor_type_number)
            health = const.Health.Warning
        return desc, health

    def decode_sensor_reading(self, reading):
        numeric = None
        output = {
            'name': self.sensor_name,
            'type': self.sensor_type,
            'id': self.sensor_number,
        }
        if reading[1] & 0b100000:
            output['unavailable'] = 1
            return SensorReading(output, self.unit_suffix)
        if self.numeric_format == 2:
            numeric = twos_complement(reading[0], 8)
        elif self.numeric_format == 1:
            numeric = ones_complement(reading[0], 8)
        elif self.numeric_format == 0:
            numeric = reading[0]
        discrete = True
        if numeric is not None:
            lowerbound = numeric - (0.5 + (self.tolerance / 2.0))
            upperbound = numeric + (0.5 + (self.tolerance / 2.0))
            lowerbound = self.decode_value(lowerbound)
            upperbound = self.decode_value(upperbound)
            output['value'] = (lowerbound + upperbound) / 2.0
            output['imprecision'] = output['value'] - lowerbound
            discrete = False
        upper = 'upper'
        lower = 'lower'
        if self.linearization == 7:
            # if the formula is 1/x, then the intuitive sense of upper and
            # lower are backwards
            upper = 'lower'
            lower = 'upper'
        output['states'] = []
        output['state_ids'] = []
        output['health'] = const.Health.Ok
        if discrete:
            for state in range(8):
                if reading[2] & (0b1 << state):
                    statedesc, health = self._decode_state(state)
                    output['health'] |= health
                    output['states'].append(statedesc)
                    output['state_ids'].append(self.assert_trap_value(state))
            if len(reading) > 3:
                for state in range(7):
                    if reading[3] & (0b1 << state):
                        statedesc, health = self._decode_state(state + 8)
                        output['health'] |= health
                        output['states'].append(statedesc)
                        output['state_ids'].append(
                            self.assert_trap_value(state + 8))
        else:
            if reading[2] & 0b1:
                output['health'] |= const.Health.Warning
                output['states'].append(lower + " non-critical threshold")
                output['state_ids'].append(self.assert_trap_value(1))
            if reading[2] & 0b10:
                output['health'] |= const.Health.Critical
                output['states'].append(lower + " critical threshold")
                output['state_ids'].append(self.assert_trap_value(2))
            if reading[2] & 0b100:
                output['health'] |= const.Health.Failed
                output['states'].append(lower + " non-recoverable threshold")
                output['state_ids'].append(self.assert_trap_value(3))
            if reading[2] & 0b1000:
                output['health'] |= const.Health.Warning
                output['states'].append(upper + " non-critical threshold")
                output['state_ids'].append(self.assert_trap_value(4))
            if reading[2] & 0b10000:
                output['health'] |= const.Health.Critical
                output['states'].append(upper + " critical threshold")
                output['state_ids'].append(self.assert_trap_value(5))
            if reading[2] & 0b100000:
                output['health'] |= const.Health.Failed
                output['states'].append(upper + " non-recoverable threshold")
                output['state_ids'].append(self.assert_trap_value(6))
        return SensorReading(output, self.unit_suffix)

    def _set_tmp_formula(self, value):
        rsp = self.ipmicmd.raw_command(netfn=4, command=0x23,
                                       data=(self.sensor_number, value))
        # skip next reading field, not used in on-demand situation
        self.decode_formula(rsp['data'][1:])

    def decode_value(self, value):
        # Take the input value and return meaningful value
        linearization = self.linearization
        if linearization > 11:  # direct calling code to get factors
            # for now, we will get the factors on demand
            # the facility is engineered such that at construction
            # time the entire BMC table should be fetchable in a reasonable
            # fashion.  However for now opt for retrieving rows as needed
            # rather than tracking all that information for a relatively
            # rare behavior
            self._set_tmp_formula(value)
            linearization = 0
        # time to compute the pre-linearization value.
        decoded = float((value * self.m + self.b) *
                        (10 ** self.resultexponent))
        if linearization == 0:
            return decoded
        elif linearization == 1:
            return math.log(decoded)
        elif linearization == 2:
            return math.log(decoded, 10)
        elif linearization == 3:
            return math.log(decoded, 2)
        elif linearization == 4:
            return math.exp(decoded)
        elif linearization == 5:
            return 10 ** decoded
        elif linearization == 6:
            return 2 ** decoded
        elif linearization == 7:
            return 1 / decoded
        elif linearization == 8:
            return decoded ** 2
        elif linearization == 9:
            return decoded ** 3
        elif linearization == 10:
            return math.sqrt(decoded)
        elif linearization == 11:
            return decoded ** (1.0/3)
        else:
            raise NotImplementedError

    def decode_formula(self, entry):
        self.m = \
            twos_complement(entry[0] + ((entry[1] & 0b11000000) << 2), 10)
        self.tolerance = entry[1] & 0b111111
        self.b = \
            twos_complement(entry[2] + ((entry[3] & 0b11000000) << 2), 10)
        self.accuracy = (entry[3] & 0b111111) + \
            (entry[4] & 0b11110000) << 2
        self.accuracyexp = (entry[4] & 0b1100) >> 2
        self.direction = entry[4] & 0b11
        # 0 = n/a, 1 = input, 2 = output
        self.resultexponent = twos_complement((entry[5] & 0b11110000) >> 4, 4)
        bexponent = twos_complement(entry[5] & 0b1111, 4)
        # might as well do the math to 'b' now rather than wait for later
        self.b = self.b * (10**bexponent)

    def tlv_decode(self, tlv, data):
        # Per IPMI 'type/length byte format
        ipmitype = (tlv & 0b11000000) >> 6
        if not len(data):
            return ""
        if ipmitype == 0:  # Unicode per 43.15 in ipmi 2.0 spec
            # the spec is not specific about encoding, assuming utf8
            return unicode(struct.pack("%dB" % len(data), *data), "utf_8")
        elif ipmitype == 1:  # BCD '+'
            tmpl = "%02X" * len(data)
            tstr = tmpl % tuple(data)
            tstr = tstr.replace("A", " ").replace("B", "-").replace("C", ".")
            return tstr.replace("D", ":").replace("E", ",").replace("F", "_")
        elif ipmitype == 2:  # 6 bit ascii, start at 0x20
            # the ordering is very peculiar and is best understood from
            # IPMI SPEC "6-bit packed ascii example
            tstr = ""
            while len(data) >= 3:  # the packing only works with 3 byte chunks
                tstr += chr((data[0] & 0b111111) + 0x20)
                tstr += chr(((data[1] & 0b1111) << 2) +
                            (data[0] >> 6) + 0x20)
                tstr += chr(((data[2] & 0b11) << 4) +
                            (data[1] >> 4) + 0x20)
                tstr += chr((data[2] >> 2) + 0x20)
            return tstr
        elif ipmitype == 3:  # ACSII+LATIN1
            return struct.pack("%dB" % len(data), *data)


class SDR(object):
    """Examine the state of sensors managed by a BMC

    Presents the data from sensor read commands as directed by the SDR in a
    reasonable format.  This module is used by the command module, and is not
    intended for consumption by external code directly

    :param ipmicmd: A Command class object
    """
    def __init__(self, ipmicmd):
        self.ipmicmd = weakref.proxy(ipmicmd)
        self.sensors = {}
        self.fru = {}
        self.read_info()

    def read_info(self):
        # first, we want to know the device id
        rsp = self.ipmicmd.xraw_command(netfn=6, command=1)
        rsp['data'] = bytearray(rsp['data'])
        self.device_id = rsp['data'][0]
        self.device_rev = rsp['data'][1] & 0b111
        # Going to ignore device available until get sdr command
        # since that provides usefully distinct state and this does not
        self.fw_major = rsp['data'][2] & 0b1111111
        self.fw_minor = "%02X" % rsp['data'][3]  # BCD encoding, oddly enough
        self.ipmiversion = rsp['data'][4]  # 51h = 1.5, 02h = 2.0
        self.mfg_id = rsp['data'][8] << 16 + rsp['data'][7] << 8 + \
            rsp['data'][6]
        self.prod_id = rsp['data'][10] << 8 + rsp['data'][9]
        if len(rsp['data']) > 11:
            self.aux_fw = self.decode_aux(rsp['data'][11:15])
        if rsp['data'][1] & 0b10000000 and rsp['data'][5] & 0b10 == 0:
            # The device has device sdrs, also does not support SDR repository
            # device, so we are meant to use an alternative mechanism to get
            # SDR data
            if rsp['data'][5] & 1:
                # The device has sensor device support, so in theory we should
                # be able to proceed
                # However at the moment, we haven't done so
                raise NotImplementedError
            return
            # We have Device SDR, without SDR Repository device, but
            # also without sensor device support, no idea how to
            # continue
        self.get_sdr()

    def get_sdr_reservation(self):
        rsp = self.ipmicmd.raw_command(netfn=0x0a, command=0x22)
        if rsp['code'] != 0:
            raise exc.IpmiException(rsp['error'])
        return rsp['data'][0] + (rsp['data'][1] << 8)

    def get_sdr(self):
        repinfo = self.ipmicmd.xraw_command(netfn=0x0a, command=0x20)
        repinfo['data'] = bytearray(repinfo['data'])
        if (repinfo['data'][0] != 0x51):
            # we only understand SDR version 51h, the only version defined
            # at time of this writing
            raise NotImplementedError
        # NOTE(jbjohnso): we actually don't need to care about 'numrecords'
        # since FFFF marks the end explicitly
        # numrecords = (rsp['data'][2] << 8) + rsp['data'][1]
        # NOTE(jbjohnso): don't care about 'free space' at the moment
        # NOTE(jbjohnso): most recent timstamp data for add and erase could be
        # handy to detect cache staleness, but for now will assume invariant
        # over life of session
        # NOTE(jbjohnso): not looking to support the various options in op
        # support, ignore those for now, reservation if some BMCs can't read
        # full SDR in one slurp
        recid = 0
        rsvid = 0  # partial 'get sdr' will require this
        offset = 0
        size = 0xff
        chunksize = 128
        self.broken_sensor_ids = {}
        while recid != 0xffff:  # per 33.12 Get SDR command, 0xffff marks end
            newrecid = 0
            currlen = 0
            sdrdata = bytearray()
            while True:  # loop until SDR fetched wholly
                if size != 0xff and rsvid == 0:
                    rsvid = self.get_sdr_reservation()
                rqdata = [rsvid & 0xff, rsvid >> 8,
                          recid & 0xff, recid >> 8,
                          offset, size]
                sdrrec = self.ipmicmd.raw_command(netfn=0x0a, command=0x23,
                                                  data=rqdata)
                if sdrrec['code'] == 0xca:
                    if size == 0xff:  # get just 5 to get header to know length
                        size = 5
                    elif size > 5:
                        size /= 2
                        # push things over such that it's less
                        # likely to be just 1 short of a read
                        # and incur a whole new request
                        size += 2
                        chunksize = size
                    continue
                if sdrrec['code'] == 0xc5:  # need a new reservation id
                    rsvid = 0
                    continue
                if sdrrec['code'] != 0:
                    raise exc.IpmiException(sdrrec['error'])
                if newrecid == 0:
                    newrecid = (sdrrec['data'][1] << 8) + sdrrec['data'][0]
                if currlen == 0:
                    currlen = sdrrec['data'][6] + 5  # compensate for header
                sdrdata.extend(sdrrec['data'][2:])
                # determine next offset to use based on current offset and the
                # size used last time.
                offset += size
                if offset >= currlen:
                    break
                if size == 5 and offset == 5:
                    # bump up size after header retrieval
                    size = chunksize
                if (offset + size) > currlen:
                    size = currlen - offset
            self.add_sdr(sdrdata)
            offset = 0
            if size != 0xff:
                size = 5
            if newrecid == recid:
                raise exc.BmcErrorException("Incorrect SDR record id from BMC")
            recid = newrecid
        for sid in self.broken_sensor_ids:
            try:
                del self.sensors[sid]
            except KeyError:
                pass

    def get_sensor_numbers(self):
        for number in self.sensors:
            if self.sensors[number].readable:
                yield number

    def add_sdr(self, sdrbytes):
        newent = SDREntry(sdrbytes, self.ipmicmd)
        if newent.sdrtype == TYPE_SENSOR:
            id = newent.sensor_number
            if id in self.sensors:
                self.broken_sensor_ids[id] = True
                return
            self.sensors[id] = newent
        elif newent.sdrtype == TYPE_FRU:
            id = newent.fru_number
            if id in self.fru:
                self.broken_sensor_ids[id] = True
                return
            self.fru[id] = newent

    def decode_aux(self, auxdata):
        # This is where manufacturers can add their own
        # decode information
        return "".join(hex(x) for x in auxdata)

if __name__ == "__main__":  # test code
    import os
    import pyghmi.ipmi.command as ipmicmd
    import sys
    password = os.environ['IPMIPASSWORD']
    bmc = sys.argv[1]
    user = sys.argv[2]
    ipmicmd = ipmicmd.Command(bmc=bmc, userid=user, password=password)
    sdr = SDR(ipmicmd)
    for number in sdr.get_sensor_numbers():
        rsp = ipmicmd.raw_command(command=0x2d, netfn=4, data=(number,))
        if 'error' in rsp:
            continue
        reading = sdr.sensors[number].decode_sensor_reading(rsp['data'])
        if reading is not None:
            print(repr(reading))