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# Copyright (c) 2015, Nordic Semiconductor
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
#
# * Redistributions of source code must retain the above copyright notice, this
# list of conditions and the following disclaimer.
#
# * Redistributions in binary form must reproduce the above copyright notice,
# this list of conditions and the following disclaimer in the documentation
# and/or other materials provided with the distribution.
#
# * Neither the name of Nordic Semiconductor ASA nor the names of its
# contributors may be used to endorse or promote products derived from
# this software without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
# DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
# SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
# CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
# OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
from enum import Enum
import struct
INIT_PACKET_USES_CRC16 = 0
INIT_PACKET_USES_HASH = 1
INIT_PACKET_EXT_USES_ECDS = 2
class PacketField(Enum):
DEVICE_TYPE = 1
DEVICE_REVISION = 2
APP_VERSION = 3
REQUIRED_SOFTDEVICES_ARRAY = 4
OPT_DATA = 5
NORDIC_PROPRIETARY_OPT_DATA_EXT_PACKET_ID = 6
NORDIC_PROPRIETARY_OPT_DATA_FIRMWARE_LENGTH = 7
NORDIC_PROPRIETARY_OPT_DATA_FIRMWARE_HASH = 8
NORDIC_PROPRIETARY_OPT_DATA_FIRMWARE_CRC16 = 9
NORDIC_PROPRIETARY_OPT_DATA_INIT_PACKET_ECDS = 10
class Packet(object):
"""
Class that implements the INIT packet format.
http://developer.nordicsemi.com/nRF51_SDK/doc/7.1.0/s110/html/a00065.html
"""
UNSIGNED_SHORT = "H"
UNSIGNED_INT = "I"
UNSIGNED_CHAR = "B"
CHAR_ARRAY = "s"
def __init__(self, init_packet_fields):
"""
:param init_packet_fields: Dictionary with packet fields
"""
self.init_packet_fields = init_packet_fields
def generate_packet(self):
"""
Generates a binary packet from provided init_packet_fields provided in constructor.
This version includes the extended data
:return str: Returns a string representing the init_packet (in binary)
"""
# Create struct format string based on keys that are
# present in self.init_packet_fields
format_string = self.__generate_struct_format_string()
args = []
# If you got error message AttributeError: 'int' object has no attribute 'value'.
# Uncomment line 84 and comment out line 85 and run 'python setup.py install'
#for key in sorted(self.init_packet_fields.keys(), key=lambda x: x):
for key in sorted(self.init_packet_fields.keys(), key=lambda x: x.value):
# Add length to fields that required that
if key in [PacketField.REQUIRED_SOFTDEVICES_ARRAY,
PacketField.OPT_DATA]:
args.append(len(self.init_packet_fields[key]))
args.extend(self.init_packet_fields[key])
else:
args.append(self.init_packet_fields[key])
return struct.pack(format_string, *args)
def __generate_struct_format_string(self):
format_string = "<" # Use little endian format with standard sizes for python,
# see https://docs.python.org/2/library/struct.html
# If you got error message AttributeError: 'int' object has no attribute 'value'.
# Uncomment line 102 and comment out line 103 and run 'python setup.py install'
#for key in sorted(self.init_packet_fields.keys(), key=lambda x: x):
for key in sorted(self.init_packet_fields.keys(), key=lambda x: x.value):
if key in [PacketField.DEVICE_TYPE,
PacketField.DEVICE_REVISION,
]:
format_string += Packet.UNSIGNED_SHORT
elif key in [PacketField.APP_VERSION]:
format_string += Packet.UNSIGNED_INT
elif key in [PacketField.REQUIRED_SOFTDEVICES_ARRAY]:
array_elements = self.init_packet_fields[key]
format_string += Packet.UNSIGNED_SHORT # Add length field to format packet
for _ in range(len(array_elements)):
format_string += Packet.UNSIGNED_SHORT
elif key in [PacketField.OPT_DATA]:
format_string += Packet.UNSIGNED_SHORT # Add length field to optional data
format_string += "{0}{1}".format(len(self.init_packet_fields[key]), Packet.CHAR_ARRAY)
elif key in [PacketField.NORDIC_PROPRIETARY_OPT_DATA_EXT_PACKET_ID]:
format_string += Packet.UNSIGNED_INT # Add the extended packet id field
elif key == PacketField.NORDIC_PROPRIETARY_OPT_DATA_FIRMWARE_LENGTH:
format_string += Packet.UNSIGNED_INT # Add the firmware length field
elif key == PacketField.NORDIC_PROPRIETARY_OPT_DATA_FIRMWARE_HASH:
format_string += "32{0}".format(Packet.CHAR_ARRAY) # SHA-256 requires 32 bytes
elif key == PacketField.NORDIC_PROPRIETARY_OPT_DATA_FIRMWARE_CRC16:
format_string += Packet.UNSIGNED_SHORT
elif key == PacketField.NORDIC_PROPRIETARY_OPT_DATA_INIT_PACKET_ECDS:
format_string += "64{0}".format(Packet.CHAR_ARRAY) # ECDS based on P-256 using SHA-256 requires 64 bytes
return format_string
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