Class StrNullField

scapy/fields.py:2215–2245

class StrNullField(StrField):
    DELIMITER = b"\x00"

    def addfield(self, pkt, s, val):
        # type: (Packet, bytes, Optional[bytes]) -> bytes
        return s + self.i2m(pkt, val) + self.DELIMITER

    def getfield(self,
                 pkt,  # type: Packet
                 s,  # type: bytes
                 ):
        # type: (...) -> Tuple[bytes, bytes]
        len_str = 0
        while True:
            len_str = s.find(self.DELIMITER, len_str)
            if len_str < 0:
                # DELIMITER not found: return empty
                return b"", s
            if len_str % len(self.DELIMITER):
                len_str += 1
            else:
                break
        return s[len_str + len(self.DELIMITER):], self.m2i(pkt, s[:len_str])

    def randval(self):
        # type: () -> RandTermString
        return RandTermString(RandNum(0, 1200), self.DELIMITER)

    def i2len(self, pkt, x):
        # type: (Optional[Packet], Any) -> int
        return super(StrNullField, self).i2len(pkt, x) + 1


class StrNullFieldUtf16(StrNullField, StrFieldUtf16):