mirror of
https://github.com/evilhero/mylar
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281 lines
8.9 KiB
Python
281 lines
8.9 KiB
Python
# Copyright (C) 2011 by clueless <clueless.nospam ! mail.com>
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#
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# Permission is hereby granted, free of charge, to any person obtaining a copy
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# of this software and associated documentation files (the "Software"), to deal
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# in the Software without restriction, including without limitation the rights
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# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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# copies of the Software, and to permit persons to whom the Software is
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# furnished to do so, subject to the following conditions:
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#
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# The above copyright notice and this permission notice shall be included in
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# all copies or substantial portions of the Software.
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#
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# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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# THE SOFTWARE.
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#
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# Version: 20111107
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#
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# Changelog
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# ---------
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# 2011-11-07 - Added support for Python2 (tested on 2.6)
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# 2011-10-03 - Fixed: moved check for end of list at the top of the while loop
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# in _decode_list (in case the list is empty) (Chris Lucas)
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# - Converted dictionary keys to str
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# 2011-04-24 - Changed date format to YYYY-MM-DD for versioning, bigger
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# integer denotes a newer version
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# - Fixed a bug that would treat False as an integral type but
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# encode it using the 'False' string, attempting to encode a
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# boolean now results in an error
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# - Fixed a bug where an integer value of 0 in a list or
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# dictionary resulted in a parse error while decoding
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#
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# 2011-04-03 - Original release
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import sys
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_py3 = sys.version_info[0] == 3
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if _py3:
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_VALID_STRING_TYPES = (str,)
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else:
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_VALID_STRING_TYPES = (str, unicode) # @UndefinedVariable
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_TYPE_INT = 1
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_TYPE_STRING = 2
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_TYPE_LIST = 3
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_TYPE_DICTIONARY = 4
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_TYPE_END = 5
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_TYPE_INVALID = 6
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# Function to determine the type of he next value/item
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# Arguments:
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# char First character of the string that is to be decoded
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# Return value:
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# Returns an integer that describes what type the next value/item is
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def _gettype(char):
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if not isinstance(char, int):
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char = ord(char)
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if char == 0x6C: # 'l'
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return _TYPE_LIST
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elif char == 0x64: # 'd'
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return _TYPE_DICTIONARY
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elif char == 0x69: # 'i'
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return _TYPE_INT
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elif char == 0x65: # 'e'
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return _TYPE_END
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elif char >= 0x30 and char <= 0x39: # '0' '9'
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return _TYPE_STRING
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else:
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return _TYPE_INVALID
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# Function to parse a string from the bendcoded data
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# Arguments:
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# data bencoded data, must be guaranteed to be a string
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# Return Value:
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# Returns a tuple, the first member of the tuple is the parsed string
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# The second member is whatever remains of the bencoded data so it can
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# be used to parse the next part of the data
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def _decode_string(data):
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end = 1
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# if py3, data[end] is going to be an int
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# if py2, data[end] will be a string
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if _py3:
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char = 0x3A
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else:
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char = chr(0x3A)
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while data[end] != char: # ':'
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end = end + 1
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strlen = int(data[:end])
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return (data[end + 1:strlen + end + 1], data[strlen + end + 1:])
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# Function to parse an integer from the bencoded data
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# Arguments:
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# data bencoded data, must be guaranteed to be an integer
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# Return Value:
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# Returns a tuple, the first member of the tuple is the parsed string
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# The second member is whatever remains of the bencoded data so it can
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# be used to parse the next part of the data
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def _decode_int(data):
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end = 1
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# if py3, data[end] is going to be an int
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# if py2, data[end] will be a string
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if _py3:
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char = 0x65
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else:
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char = chr(0x65)
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while data[end] != char: # 'e'
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end = end + 1
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return (int(data[1:end]), data[end + 1:])
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# Function to parse a bencoded list
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# Arguments:
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# data bencoded data, must be guaranted to be the start of a list
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# Return Value:
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# Returns a tuple, the first member of the tuple is the parsed list
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# The second member is whatever remains of the bencoded data so it can
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# be used to parse the next part of the data
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def _decode_list(data):
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x = []
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overflow = data[1:]
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while True: # Loop over the data
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if _gettype(overflow[0]) == _TYPE_END: # - Break if we reach the end of the list
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return (x, overflow[1:]) # and return the list and overflow
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value, overflow = _decode(overflow) #
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if isinstance(value, bool) or overflow == '': # - if we have a parse error
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return (False, False) # Die with error
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else: # - Otherwise
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x.append(value) # add the value to the list
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# Function to parse a bencoded list
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# Arguments:
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# data bencoded data, must be guaranted to be the start of a list
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# Return Value:
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# Returns a tuple, the first member of the tuple is the parsed dictionary
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# The second member is whatever remains of the bencoded data so it can
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# be used to parse the next part of the data
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def _decode_dict(data):
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x = {}
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overflow = data[1:]
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while True: # Loop over the data
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if _gettype(overflow[0]) != _TYPE_STRING: # - If the key is not a string
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return (False, False) # Die with error
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key, overflow = _decode(overflow) #
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if key == False or overflow == '': # - If parse error
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return (False, False) # Die with error
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value, overflow = _decode(overflow) #
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if isinstance(value, bool) or overflow == '': # - If parse error
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print("Error parsing value")
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print(value)
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print(overflow)
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return (False, False) # Die with error
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else:
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# don't use bytes for the key
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key = key.decode()
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x[key] = value
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if _gettype(overflow[0]) == _TYPE_END:
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return (x, overflow[1:])
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# Arguments:
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# data bencoded data in bytes format
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# Return Values:
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# Returns a tuple, the first member is the parsed data, could be a string,
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# an integer, a list or a dictionary, or a combination of those
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# The second member is the leftover of parsing, if everything parses correctly this
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# should be an empty byte string
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def _decode(data):
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btype = _gettype(data[0])
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if btype == _TYPE_INT:
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return _decode_int(data)
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elif btype == _TYPE_STRING:
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return _decode_string(data)
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elif btype == _TYPE_LIST:
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return _decode_list(data)
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elif btype == _TYPE_DICTIONARY:
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return _decode_dict(data)
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else:
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return (False, False)
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# Function to decode bencoded data
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# Arguments:
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# data bencoded data, can be str or bytes
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# Return Values:
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# Returns the decoded data on success, this coud be bytes, int, dict or list
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# or a combinatin of those
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# If an error occurs the return value is False
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def decode(data):
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# if isinstance(data, str):
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# data = data.encode()
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decoded, overflow = _decode(data)
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return decoded
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# Args: data as integer
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# return: encoded byte string
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def _encode_int(data):
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return b'i' + str(data).encode() + b'e'
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# Args: data as string or bytes
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# Return: encoded byte string
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def _encode_string(data):
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return str(len(data)).encode() + b':' + data
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# Args: data as list
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# Return: Encoded byte string, false on error
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def _encode_list(data):
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elist = b'l'
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for item in data:
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eitem = encode(item)
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if eitem == False:
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return False
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elist += eitem
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return elist + b'e'
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# Args: data as dict
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# Return: encoded byte string, false on error
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def _encode_dict(data):
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edict = b'd'
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keys = []
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for key in data:
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if not isinstance(key, _VALID_STRING_TYPES) and not isinstance(key, bytes):
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return False
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keys.append(key)
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keys.sort()
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for key in keys:
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ekey = encode(key)
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eitem = encode(data[key])
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if ekey == False or eitem == False:
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return False
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edict += ekey + eitem
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return edict + b'e'
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# Function to encode a variable in bencoding
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# Arguments:
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# data Variable to be encoded, can be a list, dict, str, bytes, int or a combination of those
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# Return Values:
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# Returns the encoded data as a byte string when successful
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# If an error occurs the return value is False
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def encode(data):
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if isinstance(data, bool):
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return False
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elif isinstance(data, int):
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return _encode_int(data)
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elif isinstance(data, bytes):
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return _encode_string(data)
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elif isinstance(data, _VALID_STRING_TYPES):
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return _encode_string(data.encode())
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elif isinstance(data, list):
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return _encode_list(data)
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elif isinstance(data, dict):
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return _encode_dict(data)
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else:
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return False
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