dfu_transport.py

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# Python specific imports
import abc
import logging

# Nordic Semiconductor imports

logger = logging.getLogger(__name__)


class DfuEvent:
    PROGRESS_EVENT = 1


class DfuTransport(object):
    """
    This class as an abstract base class inherited from when implementing transports.

    The class is generic in nature, the underlying implementation may have missing semantic
    than this class describes. But the intent is that the implementer shall follow the semantic as
    best as she can.
    """
    __metaclass__ = abc.ABCMeta

    OP_CODE = {
        'CreateObject'          : 0x01,
        'SetPRN'                : 0x02,
        'CalcChecSum'           : 0x03,
        'Execute'               : 0x04,
        'ReadObject'            : 0x06,
        'Response'              : 0x60,
    }

    RES_CODE = {
        'InvalidCode'           : 0x00,
        'Success'               : 0x01,
        'NotSupported'          : 0x02,
        'InvalidParameter'      : 0x03,
        'InsufficientResources' : 0x04,
        'InvalidObject'         : 0x05,
        'InvalidSignature'      : 0x06,
        'UnsupportedType'       : 0x07,
        'OperationNotPermitted' : 0x08,
        'OperationFailed'       : 0x0A,
        'ExtendedError'         : 0x0B,
    }

    EXT_ERROR_CODE = [
        "No extended error code has been set. This error indicates an implementation problem.",
        "Invalid error code. This error code should never be used outside of development.",
        "The format of the command was incorrect. This error code is not used in the current implementation, because @ref NRF_DFU_RES_CODE_OP_CODE_NOT_SUPPORTED and @ref NRF_DFU_RES_CODE_INVALID_PARAMETER cover all possible format errors.",
        "The command was successfully parsed, but it is not supported or unknown.",
        "The init command is invalid. The init packet either has an invalid update type or it is missing required fields for the update type (for example, the init packet for a SoftDevice update is missing the SoftDevice size field).",
        "The firmware version is too low. For an application, the version must be greater than the current application. For a bootloader, it must be greater than or equal to the current version. This requirement prevents downgrade attacks.""", 
        "The hardware version of the device does not match the required hardware version for the update.",
        "The array of supported SoftDevices for the update does not contain the FWID of the current SoftDevice.",
        "The init packet does not contain a signature. This error code is not used in the current implementation, because init packets without a signature are regarded as invalid.",
        "The hash type that is specified by the init packet is not supported by the DFU bootloader.",
        "The hash of the firmware image cannot be calculated.",
        "The type of the signature is unknown or not supported by the DFU bootloader.",
        "The hash of the received firmware image does not match the hash in the init packet.",
        "The available space on the device is insufficient to hold the firmware.",
    ]

    @abc.abstractmethod
    def __init__(self):
        self.callbacks = {}


    @abc.abstractmethod
    def open(self):
        """
        Open a port if appropriate for the transport.
        :return:
        """
        pass


    @abc.abstractmethod
    def close(self):
        """
        Close a port if appropriate for the transport.
        :return:
        """
        pass

    @abc.abstractmethod
    def send_init_packet(self, init_packet):
        """
        Send init_packet to device.

        This call will block until init_packet is sent and transfer of packet is complete.

        :param init_packet: Init packet as a str.
        :return:
        """
        pass


    @abc.abstractmethod
    def send_firmware(self, firmware):
        """
        Start sending firmware to device.

        This call will block until transfer of firmware is complete.

        :param firmware:
        :return:
        """
        pass


    def register_events_callback(self, event_type, callback):
        """
        Register a callback.

        :param DfuEvent callback:
        :return: None
        """
        if event_type not in self.callbacks:
            self.callbacks[event_type] = []

        self.callbacks[event_type].append(callback)


    def _send_event(self, event_type, **kwargs):
        """
        Method for sending events to registered callbacks.

        If callbacks throws exceptions event propagation will stop and this method be part of the track trace.

        :param DfuEvent event_type:
        :param kwargs: Arguments to callback function
        :return:
        """
        if event_type in self.callbacks.keys():
            for callback in self.callbacks[event_type]:
                callback(**kwargs)