398 lines
14 KiB
Python
398 lines
14 KiB
Python
|
import logging
|
||
|
|
import struct
|
||
|
|
import ctypes
|
||
|
|
from coapthon.messages.request import Request
|
||
|
|
from coapthon.messages.response import Response
|
||
|
|
from coapthon.messages.option import Option
|
||
|
|
from coapthon import defines
|
||
|
|
from coapthon.messages.message import Message
|
||
|
|
|
||
|
|
__author__ = 'Giacomo Tanganelli'
|
||
|
|
|
||
|
|
logger = logging.getLogger(__name__)
|
||
|
|
|
||
|
|
|
||
|
|
class Serializer(object):
|
||
|
|
"""
|
||
|
|
Serializer class to serialize and deserialize CoAP message to/from udp streams.
|
||
|
|
"""
|
||
|
|
@staticmethod
|
||
|
|
def deserialize(datagram, source):
|
||
|
|
"""
|
||
|
|
De-serialize a stream of byte to a message.
|
||
|
|
|
||
|
|
:param datagram: the incoming udp message
|
||
|
|
:param source: the source address and port (ip, port)
|
||
|
|
:return: the message
|
||
|
|
:rtype: Message
|
||
|
|
"""
|
||
|
|
try:
|
||
|
|
fmt = "!BBH"
|
||
|
|
pos = struct.calcsize(fmt)
|
||
|
|
s = struct.Struct(fmt)
|
||
|
|
values = s.unpack_from(datagram)
|
||
|
|
first = values[0]
|
||
|
|
code = values[1]
|
||
|
|
mid = values[2]
|
||
|
|
version = (first & 0xC0) >> 6
|
||
|
|
message_type = (first & 0x30) >> 4
|
||
|
|
token_length = (first & 0x0F)
|
||
|
|
if Serializer.is_response(code):
|
||
|
|
message = Response()
|
||
|
|
message.code = code
|
||
|
|
elif Serializer.is_request(code):
|
||
|
|
message = Request()
|
||
|
|
message.code = code
|
||
|
|
else:
|
||
|
|
message = Message()
|
||
|
|
message.source = source
|
||
|
|
message.destination = None
|
||
|
|
message.version = version
|
||
|
|
message.type = message_type
|
||
|
|
message.mid = mid
|
||
|
|
if token_length > 0:
|
||
|
|
fmt = "%ss" % token_length
|
||
|
|
s = struct.Struct(fmt)
|
||
|
|
token_value = s.unpack_from(datagram[pos:])[0]
|
||
|
|
message.token = token_value
|
||
|
|
else:
|
||
|
|
message.token = None
|
||
|
|
|
||
|
|
pos += token_length
|
||
|
|
current_option = 0
|
||
|
|
values = datagram[pos:]
|
||
|
|
length_packet = len(values)
|
||
|
|
pos = 0
|
||
|
|
while pos < length_packet:
|
||
|
|
next_byte = struct.unpack("B", values[pos])[0]
|
||
|
|
pos += 1
|
||
|
|
if next_byte != int(defines.PAYLOAD_MARKER):
|
||
|
|
# the first 4 bits of the byte represent the option delta
|
||
|
|
# delta = self._reader.read(4).uint
|
||
|
|
num, option_length, pos = Serializer.read_option_value_len_from_byte(next_byte, pos, values)
|
||
|
|
current_option += num
|
||
|
|
# read option
|
||
|
|
try:
|
||
|
|
option_item = defines.OptionRegistry.LIST[current_option]
|
||
|
|
except KeyError:
|
||
|
|
(opt_critical, _, _) = defines.OptionRegistry.get_option_flags(current_option)
|
||
|
|
if opt_critical:
|
||
|
|
raise AttributeError("Critical option %s unknown" % current_option)
|
||
|
|
else:
|
||
|
|
# If the non-critical option is unknown
|
||
|
|
# (vendor-specific, proprietary) - just skip it
|
||
|
|
#log.err("unrecognized option %d" % current_option)
|
||
|
|
pass
|
||
|
|
else:
|
||
|
|
if option_length == 0:
|
||
|
|
value = None
|
||
|
|
elif option_item.value_type == defines.INTEGER:
|
||
|
|
tmp = values[pos: pos + option_length]
|
||
|
|
value = 0
|
||
|
|
for b in tmp:
|
||
|
|
value = (value << 8) | struct.unpack("B", b)[0]
|
||
|
|
elif option_item.value_type == defines.OPAQUE:
|
||
|
|
tmp = values[pos: pos + option_length]
|
||
|
|
value = bytearray(tmp)
|
||
|
|
else:
|
||
|
|
tmp = values[pos: pos + option_length]
|
||
|
|
value = ""
|
||
|
|
for b in tmp:
|
||
|
|
value += str(b)
|
||
|
|
|
||
|
|
option = Option()
|
||
|
|
option.number = current_option
|
||
|
|
option.value = Serializer.convert_to_raw(current_option, value, option_length)
|
||
|
|
|
||
|
|
message.add_option(option)
|
||
|
|
if option.number == defines.OptionRegistry.CONTENT_TYPE.number:
|
||
|
|
message.payload_type = option.value
|
||
|
|
finally:
|
||
|
|
pos += option_length
|
||
|
|
else:
|
||
|
|
|
||
|
|
if length_packet <= pos:
|
||
|
|
# log.err("Payload Marker with no payload")
|
||
|
|
raise AttributeError("Packet length %s, pos %s" % (length_packet, pos))
|
||
|
|
message.payload = ""
|
||
|
|
payload = values[pos:]
|
||
|
|
for b in payload:
|
||
|
|
message.payload += str(b)
|
||
|
|
pos += 1
|
||
|
|
return message
|
||
|
|
except AttributeError:
|
||
|
|
return defines.Codes.BAD_REQUEST.number
|
||
|
|
except struct.error:
|
||
|
|
return defines.Codes.BAD_REQUEST.number
|
||
|
|
|
||
|
|
@staticmethod
|
||
|
|
def serialize(message):
|
||
|
|
"""
|
||
|
|
Serialize a message to a udp packet
|
||
|
|
|
||
|
|
:type message: Message
|
||
|
|
:param message: the message to be serialized
|
||
|
|
:rtype: stream of byte
|
||
|
|
:return: the message serialized
|
||
|
|
"""
|
||
|
|
fmt = "!BBH"
|
||
|
|
|
||
|
|
if message.token is None or message.token == "":
|
||
|
|
tkl = 0
|
||
|
|
else:
|
||
|
|
tkl = len(message.token)
|
||
|
|
tmp = (defines.VERSION << 2)
|
||
|
|
tmp |= message.type
|
||
|
|
tmp <<= 4
|
||
|
|
tmp |= tkl
|
||
|
|
values = [tmp, message.code, message.mid]
|
||
|
|
|
||
|
|
if message.token is not None and tkl > 0:
|
||
|
|
|
||
|
|
for b in str(message.token):
|
||
|
|
fmt += "c"
|
||
|
|
values.append(b)
|
||
|
|
|
||
|
|
options = Serializer.as_sorted_list(message.options) # already sorted
|
||
|
|
lastoptionnumber = 0
|
||
|
|
for option in options:
|
||
|
|
|
||
|
|
# write 4-bit option delta
|
||
|
|
optiondelta = option.number - lastoptionnumber
|
||
|
|
optiondeltanibble = Serializer.get_option_nibble(optiondelta)
|
||
|
|
tmp = (optiondeltanibble << defines.OPTION_DELTA_BITS)
|
||
|
|
|
||
|
|
# write 4-bit option length
|
||
|
|
optionlength = option.length
|
||
|
|
optionlengthnibble = Serializer.get_option_nibble(optionlength)
|
||
|
|
tmp |= optionlengthnibble
|
||
|
|
fmt += "B"
|
||
|
|
values.append(tmp)
|
||
|
|
|
||
|
|
# write extended option delta field (0 - 2 bytes)
|
||
|
|
if optiondeltanibble == 13:
|
||
|
|
fmt += "B"
|
||
|
|
values.append(optiondelta - 13)
|
||
|
|
elif optiondeltanibble == 14:
|
||
|
|
fmt += "H"
|
||
|
|
values.append(optiondelta - 269)
|
||
|
|
|
||
|
|
# write extended option length field (0 - 2 bytes)
|
||
|
|
if optionlengthnibble == 13:
|
||
|
|
fmt += "B"
|
||
|
|
values.append(optionlength - 13)
|
||
|
|
elif optionlengthnibble == 14:
|
||
|
|
fmt += "H"
|
||
|
|
values.append(optionlength - 269)
|
||
|
|
|
||
|
|
# write option value
|
||
|
|
if optionlength > 0:
|
||
|
|
opt_type = defines.OptionRegistry.LIST[option.number].value_type
|
||
|
|
if opt_type == defines.INTEGER:
|
||
|
|
words = Serializer.int_to_words(option.value, optionlength, 8)
|
||
|
|
for num in range(0, optionlength):
|
||
|
|
fmt += "B"
|
||
|
|
values.append(words[num])
|
||
|
|
elif opt_type == defines.STRING:
|
||
|
|
for b in str(option.value):
|
||
|
|
fmt += "c"
|
||
|
|
values.append(b)
|
||
|
|
else:
|
||
|
|
for b in option.value:
|
||
|
|
fmt += "B"
|
||
|
|
values.append(b)
|
||
|
|
|
||
|
|
|
||
|
|
# update last option number
|
||
|
|
lastoptionnumber = option.number
|
||
|
|
|
||
|
|
payload = message.payload
|
||
|
|
|
||
|
|
if payload is not None and len(payload) > 0:
|
||
|
|
# if payload is present and of non-zero length, it is prefixed by
|
||
|
|
# an one-byte Payload Marker (0xFF) which indicates the end of
|
||
|
|
# options and the start of the payload
|
||
|
|
|
||
|
|
fmt += "B"
|
||
|
|
values.append(defines.PAYLOAD_MARKER)
|
||
|
|
|
||
|
|
for b in str(payload):
|
||
|
|
fmt += "c"
|
||
|
|
values.append(b)
|
||
|
|
|
||
|
|
datagram = None
|
||
|
|
if values[1] is None:
|
||
|
|
values[1] = 0
|
||
|
|
try:
|
||
|
|
s = struct.Struct(fmt)
|
||
|
|
datagram = ctypes.create_string_buffer(s.size)
|
||
|
|
s.pack_into(datagram, 0, *values)
|
||
|
|
except struct.error:
|
||
|
|
# The .exception method will report on the exception encountered
|
||
|
|
# and provide a traceback.
|
||
|
|
logging.exception('Failed to pack structure')
|
||
|
|
|
||
|
|
return datagram
|
||
|
|
|
||
|
|
@staticmethod
|
||
|
|
def is_request(code):
|
||
|
|
"""
|
||
|
|
Checks if is request.
|
||
|
|
|
||
|
|
:return: True, if is request
|
||
|
|
"""
|
||
|
|
return defines.REQUEST_CODE_LOWER_BOUND <= code <= defines.REQUEST_CODE_UPPER_BOUND
|
||
|
|
|
||
|
|
@staticmethod
|
||
|
|
def is_response(code):
|
||
|
|
"""
|
||
|
|
Checks if is response.
|
||
|
|
|
||
|
|
:return: True, if is response
|
||
|
|
"""
|
||
|
|
return defines.RESPONSE_CODE_LOWER_BOUND <= code <= defines.RESPONSE_CODE_UPPER_BOUND
|
||
|
|
|
||
|
|
@staticmethod
|
||
|
|
def read_option_value_from_nibble(nibble, pos, values):
|
||
|
|
"""
|
||
|
|
Calculates the value used in the extended option fields.
|
||
|
|
|
||
|
|
:param nibble: the 4-bit option header value.
|
||
|
|
:return: the value calculated from the nibble and the extended option value.
|
||
|
|
"""
|
||
|
|
if nibble <= 12:
|
||
|
|
return nibble, pos
|
||
|
|
elif nibble == 13:
|
||
|
|
tmp = struct.unpack("!B", values[pos])[0] + 13
|
||
|
|
pos += 1
|
||
|
|
return tmp, pos
|
||
|
|
elif nibble == 14:
|
||
|
|
s = struct.Struct("!H")
|
||
|
|
tmp = s.unpack_from(values[pos:])[0] + 269
|
||
|
|
pos += 2
|
||
|
|
return tmp, pos
|
||
|
|
else:
|
||
|
|
raise AttributeError("Unsupported option nibble " + str(nibble))
|
||
|
|
|
||
|
|
@staticmethod
|
||
|
|
def read_option_value_len_from_byte(byte, pos, values):
|
||
|
|
"""
|
||
|
|
Calculates the value and length used in the extended option fields.
|
||
|
|
|
||
|
|
:param byte: 1-byte option header value.
|
||
|
|
:return: the value and length, calculated from the header including the extended fields.
|
||
|
|
"""
|
||
|
|
h_nibble = (byte & 0xF0) >> 4
|
||
|
|
l_nibble = byte & 0x0F
|
||
|
|
value = 0
|
||
|
|
length = 0
|
||
|
|
if h_nibble <= 12:
|
||
|
|
value = h_nibble
|
||
|
|
elif h_nibble == 13:
|
||
|
|
value = struct.unpack("!B", values[pos])[0] + 13
|
||
|
|
pos += 1
|
||
|
|
elif h_nibble == 14:
|
||
|
|
s = struct.Struct("!H")
|
||
|
|
value = s.unpack_from(values[pos:])[0] + 269
|
||
|
|
pos += 2
|
||
|
|
else:
|
||
|
|
raise AttributeError("Unsupported option number nibble " + str(h_nibble))
|
||
|
|
|
||
|
|
if l_nibble <= 12:
|
||
|
|
length = l_nibble
|
||
|
|
elif l_nibble == 13:
|
||
|
|
length = struct.unpack("!B", values[pos])[0] + 13
|
||
|
|
pos += 1
|
||
|
|
elif l_nibble == 14:
|
||
|
|
length = s.unpack_from(values[pos:])[0] + 269
|
||
|
|
pos += 2
|
||
|
|
else:
|
||
|
|
raise AttributeError("Unsupported option length nibble " + str(l_nibble))
|
||
|
|
return value, length, pos
|
||
|
|
|
||
|
|
@staticmethod
|
||
|
|
def convert_to_raw(number, value, length):
|
||
|
|
"""
|
||
|
|
Get the value of an option as a ByteArray.
|
||
|
|
|
||
|
|
:param number: the option number
|
||
|
|
:param value: the option value
|
||
|
|
:param length: the option length
|
||
|
|
:return: the value of an option as a BitArray
|
||
|
|
"""
|
||
|
|
|
||
|
|
opt_type = defines.OptionRegistry.LIST[number].value_type
|
||
|
|
|
||
|
|
if length == 0 and opt_type != defines.INTEGER:
|
||
|
|
return bytearray()
|
||
|
|
if length == 0 and opt_type == defines.INTEGER:
|
||
|
|
return 0
|
||
|
|
if isinstance(value, tuple):
|
||
|
|
value = value[0]
|
||
|
|
if isinstance(value, unicode):
|
||
|
|
value = str(value)
|
||
|
|
if isinstance(value, str):
|
||
|
|
return bytearray(value, "utf-8")
|
||
|
|
elif isinstance(value, int):
|
||
|
|
return value
|
||
|
|
else:
|
||
|
|
return bytearray(value)
|
||
|
|
|
||
|
|
@staticmethod
|
||
|
|
def as_sorted_list(options):
|
||
|
|
"""
|
||
|
|
Returns all options in a list sorted according to their option numbers.
|
||
|
|
|
||
|
|
:return: the sorted list
|
||
|
|
"""
|
||
|
|
if len(options) > 0:
|
||
|
|
options.sort(None, key=lambda o: o.number)
|
||
|
|
return options
|
||
|
|
|
||
|
|
@staticmethod
|
||
|
|
def get_option_nibble(optionvalue):
|
||
|
|
"""
|
||
|
|
Returns the 4-bit option header value.
|
||
|
|
|
||
|
|
:param optionvalue: the option value (delta or length) to be encoded.
|
||
|
|
:return: the 4-bit option header value.
|
||
|
|
"""
|
||
|
|
if optionvalue <= 12:
|
||
|
|
return optionvalue
|
||
|
|
elif optionvalue <= 255 + 13:
|
||
|
|
return 13
|
||
|
|
elif optionvalue <= 65535 + 269:
|
||
|
|
return 14
|
||
|
|
else:
|
||
|
|
raise AttributeError("Unsupported option delta " + optionvalue)
|
||
|
|
|
||
|
|
@staticmethod
|
||
|
|
def int_to_words(int_val, num_words=4, word_size=32):
|
||
|
|
"""
|
||
|
|
Convert a int value to bytes.
|
||
|
|
|
||
|
|
:param int_val: an arbitrary length Python integer to be split up.
|
||
|
|
Network byte order is assumed. Raises an IndexError if width of
|
||
|
|
integer (in bits) exceeds word_size * num_words.
|
||
|
|
|
||
|
|
:param num_words: number of words expected in return value tuple.
|
||
|
|
|
||
|
|
:param word_size: size/width of individual words (in bits).
|
||
|
|
|
||
|
|
:return: a list of fixed width words based on provided parameters.
|
||
|
|
"""
|
||
|
|
max_int = 2 ** (word_size*num_words) - 1
|
||
|
|
max_word_size = 2 ** word_size - 1
|
||
|
|
|
||
|
|
if not 0 <= int_val <= max_int:
|
||
|
|
raise AttributeError('integer %r is out of bounds!' % hex(int_val))
|
||
|
|
|
||
|
|
words = []
|
||
|
|
for _ in range(num_words):
|
||
|
|
word = int_val & max_word_size
|
||
|
|
words.append(int(word))
|
||
|
|
int_val >>= word_size
|
||
|
|
words.reverse()
|
||
|
|
|
||
|
|
return words
|