def _deserialize(string):
"""
Converts a string to a readable packet
Args:
string: a serialized packet (in a string form)
Returns:
The deserialized packet.
Raises:
PacketException: If the packet header is corrupt, a PacketException will be raised.
"""
# Read the packet header
(packetType, _comma, tail) = string.partition(",")
try :
packetType = int(packetType)
# Check if the packet type has an invalid value. If so, an exception will be raised.
Packet_TYPE.reverse_mapping[packetType]
except Exception :
raise PacketException("Invalid packet string: Unknown packet type")
(priority, _comma, tail) = tail.partition(",")
try :
priority = int(priority)
except Exception :
raise PacketException("Invalid packet string: packet priority must be an integer")
# Create the packet
p = _Packet(packetType, priority)
p._setData(tail)
# Return the readable packet
return p
def __commonReadCode(self, typeLabel, returnType):
"""
Code shared by all read operations
Args:
typeLabel: The type label (i.e. int for integer values, string for strings, and so on)
returnType: The value type to return (i.e. str for strings, int for integers, and so on).
Returns:
A value read from the packet.
Raises:
PacketException: this exceptions will be raised when the packet's current value does not
match with the type label and when the packet value and the type label do not match.
"""
(label, _dot, tail) = self.__data.partition("·")
if (typeLabel != label):
raise PacketException("Can't read a " +
self.__extractTypeName(returnType) +
" value")
(value, _dot, tail) = tail.partition("·")
try:
returnValue = returnType(value)
except Exception:
raise PacketException(
"Invalid packet string: label and data types do not match")
# Everything went OK => discard the read data
self.__data = tail
# Return the read value
return returnValue
def __commonWriteCode(self, value, dataType, field, checkType):
"""
Code shared by all write operations
Args:
value: the value to write into the packet
dataType: the expected value datatype (i.e. integer, boolean, float,...)
field: the label to use in the data string
checkType: when True, the value's data type will be checked. When False,
the value will be written directly into the data string.
Returns:
Nothing
Raises:
PacketException: these exceptions will be raised when type errors are detected
and when the packet has not enough room to hold the value.
"""
if checkType and not isinstance(value, dataType):
raise PacketException("The given value is not an " +
self.__extractTypeName(str(dataType)) +
" instance")
dataToAdd = str(value)
newLength = len(self.__data) + len(field) + len(dataToAdd) + 2
if (newLength > 65000):
# The maximum TCP segment length is 65536 bytes. 536 bytes are reserved for the packet header.
raise PacketException("There\'s not enough space to hold a " + self.__extractTypeName(str(dataType))\
+ " value")
self.__data += field + '·' + dataToAdd + '·'
def writeString(self, value):
"""
Writes a string into the packet
Args:
value: a string
Raises:
PacketException: these exceptions will be raised when type errors are detected
and when the packet has not enough room to hold the value.
"""
if not (isinstance(value, str) or isinstance(value, unicode)):
raise PacketException("The given value is not an " + self.__extractTypeName(str) + " instance")
if '$' in value :
raise PacketException('Strings cannot contain the \'$\' character')
self.__commonWriteCode(value, str, _DATA_TYPE.STRING, False)
def writeBool(self, value):
"""
Writes a boolean value into the packet.
Args:
value: a bool value
Raises:
PacketException: these exceptions will be raised when type errors are detected
and when the packet has not enough room to hold the value.
"""
if not isinstance(value, bool) :
raise PacketException("The given value is not a " + self.__extractTypeName(str(bool)) + " instance")
if (value) :
self.writeInt(1)
else :
self.writeInt(0)