198 lines
8.3 KiB
Python
198 lines
8.3 KiB
Python
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#! /usr/bin/python3
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"""
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@file mib_packet_content_parser.py
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@brief Generic File Parser class
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@details
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Used by the MIB Exporter. There are multiple functions which are abstract and should
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be implemented by a custom parser implementation.
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A file list to parse must be supplied.
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Child classes fill out the MIB table (self.mib_table)
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@author R. Mueller
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@date 14.11.2019
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"""
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import enum
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from abc import abstractmethod
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from typing import Dict
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class FileParserModes(enum.Enum):
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REGULAR = enum.auto(),
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MOVING_WINDOW = enum.auto()
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class FileParser:
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"""
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This parent class gathers common file parser operations into a super class.
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The user should do the following to use this base class:
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1. Create a custom parser class which implements this class and implement the abstract
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functions
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2. Set the parser mode
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3. Call parse_files. Additional arguments and keyword arguments can be supplied as well and
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will be passed through to the abstract function implementations.
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"""
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def __init__(self, file_list):
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if len(file_list) == 0:
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print("File list is empty !")
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self.file_list_empty = True
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else:
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self.file_list_empty = False
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self.file_list = file_list
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# Can be used to have unique key in MIB tables
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self.index = 0
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# Initialize empty MIB table which will be filled by specific parser implementation
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self.mib_table = dict()
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self.__parser_mode = FileParserModes.REGULAR
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self.__parser_args = 0
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self.__debug_moving_window = False
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self.__debug_moving_window_filename = ""
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self._verbose_level = 1
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def set_regular_parser_mode(self):
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"""
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Set regular parsing mode. This will be the default, so it is not strictly necessary to call
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this.
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:return:
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"""
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self.__parser_mode = FileParserModes.REGULAR
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def set_moving_window_mode(self, moving_window_size: int):
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"""
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Set moving window parsing mode
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:param moving_window_size:
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:return:
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"""
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self.__parser_mode = FileParserModes.MOVING_WINDOW
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self.__parser_args = moving_window_size
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def set_verbosity(self, verbose_level: int):
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self._verbose_level = verbose_level
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def enable_moving_window_debugging(self, file_name: str):
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self.__debug_moving_window = True
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self.__debug_moving_window_filename = file_name
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def parse_files(self, *args: any, **kwargs) -> Dict:
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"""
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Core method which is called to parse the files
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:param args: Optional positional arguments. Passed on the file parser
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:param kwargs: Optional keyword arguments. Passed on to file parser
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:return: Returns the mib table dictionary.
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"""
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if self.file_list_empty:
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print(f"Nothing to parse, supplied file list is empty!")
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return self.mib_table
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if self.__parser_mode == FileParserModes.REGULAR:
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for file_name in self.file_list:
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# Implemented by child class ! Fill out info table (self.mib_table) in this routine
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self._handle_file_parsing(file_name, *args, **kwargs)
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# Can be implemented by child class to edit the table after it is finished.
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# default implementation is empty
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self._post_parsing_operation()
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elif self.__parser_mode == FileParserModes.MOVING_WINDOW:
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for file_name in self.file_list:
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self.__parse_file_with_moving_window(file_name, *args, **kwargs)
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self._post_parsing_operation()
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return self.mib_table
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@abstractmethod
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def _handle_file_parsing(self, file_name: str, *args, **kwargs):
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"""
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Implemented by child class. The developer should fill the info table (self.mib_table)
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in this routine
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:param file_name:
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:param args: Additional arguments passed through the parse_files method.
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:param kwargs: Additional keyword arguments passed through the parse_files method.
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:return: Nothing. Fill out the member dictionary self.mib_table in the function instead.
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"""
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pass
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@abstractmethod
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def _handle_file_parsing_moving_window(
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self, file_name: str, current_line: int, moving_window_size: int, moving_window: list,
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*args, **kwargs):
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"""
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This will be called for the MOVING_WINDOW parser mode.
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:param file_name: Current file name
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:param current_line: Current line number.
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:param moving_window_size: Size of the moving window
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:param moving_window: Current moving window. The last entry of the moving window
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is the current line number
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:return: Nothing. Fill out the member dictionary self.mib_table in the function instead.
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"""
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pass
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@abstractmethod
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def _post_parsing_operation(self):
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"""
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# Can be implemented by child class to perform post parsing operations (e.g. setting a
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flag or editting MIB table entries)
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:return:
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"""
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def __parse_file_with_moving_window(self, file_name: str, *args, **kwargs):
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all_lines = self._open_file(file_name=file_name)
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moving_window_size = self.__parser_args
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if moving_window_size == 0:
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print("Moving window size is 0!")
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return
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moving_window = [""] * moving_window_size
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for line_idx, line in enumerate(all_lines):
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if self.__debug_moving_window and self.__debug_moving_window_filename in file_name:
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print(f"Moving window pre line anaylsis line {line_idx}")
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print(moving_window)
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# The moving window will start with only the bottom being in the file
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if line_idx == 0:
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moving_window[self.__parser_args - 1] = line
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# More and more of the window is inside the file now
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elif line_idx < moving_window_size:
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for idx in range(line_idx, 0, -1):
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moving_window[moving_window_size - 1 - idx] = \
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moving_window[moving_window_size - idx]
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moving_window[moving_window_size - 1] = line
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# The full window is inside the file now.
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elif line_idx >= moving_window_size:
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for idx in range(moving_window_size - 1):
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moving_window[idx] = moving_window[idx + 1]
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moving_window[moving_window_size - 1] = line
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if self.__debug_moving_window and self.__debug_moving_window_filename in file_name:
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print(f"Moving window post line anaylsis line {line_idx}")
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print(moving_window)
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self._handle_file_parsing_moving_window(
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file_name, line_idx, moving_window_size, moving_window, *args, **kwargs
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)
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# Now the moving window moved past the end of the file. Sections which are outside
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# the file are assigned an empty string until the window has moved out of file completely
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for remaining_windows_idx in range(moving_window_size):
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if self.__debug_moving_window and self.__debug_moving_window_filename in file_name:
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print(f"Moving window pre line analysis post EOF")
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print(moving_window)
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num_entries_to_clear = remaining_windows_idx + 1
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for idx_to_clear in range(num_entries_to_clear):
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moving_window[moving_window_size - 1 - idx_to_clear] = ""
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for idx_to_reassign in range(moving_window_size - 1 - num_entries_to_clear):
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moving_window[idx_to_reassign] = moving_window[idx_to_reassign + 1]
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if self.__debug_moving_window and self.__debug_moving_window_filename in file_name:
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print(f"Moving window post line anaylsis post EOF")
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print(moving_window)
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pass
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@staticmethod
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def _open_file(file_name: str) -> list:
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"""
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Open a file, attempting common encodings utf-8 and cp1252
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:param file_name:
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:return:
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"""
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try:
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file = open(file_name, 'r', encoding='utf-8')
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all_lines = file.readlines()
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except UnicodeDecodeError:
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print("ReturnValueParser: Decoding error with file " + file_name)
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file = open(file_name, 'r', encoding='cp1252')
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all_lines = file.readlines()
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return all_lines
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