Python fields.BitField方法代码示例

# 需要导入模块: from scapy import fields [as 别名]
# 或者: from scapy.fields import BitField [as 别名]
def getfield(self, pkt, s):
        # type: (Optional[packet.Packet], Union[str, Tuple[str, int]]) -> Tuple[Union[Tuple[str, int], str], int]  # noqa: E501
        """
        :param packet.Packet|None pkt: the packet instance containing this field instance; probably unused.  # noqa: E501
        :param str|(str, int) s: either a str if size%8==0 or a tuple with the string to parse from and the number of  # noqa: E501
          bits already consumed by previous bitfield-compatible fields.
        :return: (str|(str, int), int): Returns the remaining string and the parsed value. May return a tuple if there  # noqa: E501
          are remaining bits to parse in the first byte. Returned value is equal to default value  # noqa: E501
        :raises: AssertionError
        """
        r = super(HPackMagicBitField, self).getfield(pkt, s)
        assert (
            isinstance(r, tuple) and
            len(r) == 2 and
            isinstance(r[1], six.integer_types)
        ), 'Second element of BitField.getfield return value expected to be an int or a long; API change detected'  # noqa: E501
        assert r[1] == self._magic, 'Invalid value parsed from s; error in class guessing detected!'  # noqa: E501
        return r 

# 需要导入模块: from scapy import fields [as 别名]
# 或者: from scapy.fields import BitField [as 别名]
def addfield(self, pkt, s, val):
        # type: (Optional[packet.Packet], Union[str, Tuple[str, int, int]], int) -> str  # noqa: E501
        """
          An AbstractUVarIntField prefix always consumes the remaining bits
          of a BitField;if no current BitField is in use (no tuple in
          entry) then the prefix length is 8 bits and the whole byte is to
          be consumed

        :param packet.Packet|None pkt: the packet containing this field.
          Probably unused.
        :param str|(str, int, long) s: the string to append this field to.
          A tuple indicates that some bits were already generated by another
          bitfield-compatible field. This MUST be the case if "size" is not 8.
          The int is the number of bits already generated in the first byte of
          the str. The long is the value that was generated by the previous
          bitfield-compatible fields.
        :param int val: the positive or null value to be added.
        :return: str: s concatenated with the machine representation of this
          field.
        :raises: AssertionError
        """
        assert(val >= 0)
        if isinstance(s, bytes):
            assert self.size == 8, 'EINVAL: s: tuple expected when prefix_len is not a full byte'  # noqa: E501
            return s + self.i2m(pkt, val)

        # s is a tuple
        # assert(s[1] >= 0)
        # assert(s[2] >= 0)
        # assert (8 - s[1]) == self.size, 'EINVAL: s: not enough bits remaining in current byte to read the prefix'  # noqa: E501

        if val >= self._max_value:
            return s[0] + chb((s[2] << self.size) + self._max_value) + self.i2m(pkt, val)[1:]  # noqa: E501
        # This AbstractUVarIntField is only one byte long; setting the prefix value  # noqa: E501
        # and appending the resulting byte to the string
        return s[0] + chb((s[2] << self.size) + orb(self.i2m(pkt, val)))