BenDcode
A python module for decoding bencoded data
Bencoding
Bencoding is a meta data representation format fot the BitTorrent Protocol (BTP). The Augmented BNF syntax for Bencoding is given below
dictionary = "d" 1*(string anytype) "e"
list = "l" 1*anytype "e"
integer = "i" signumber "e"
string = number ":" <number long sequence of any CHAR>
anytype = dictionary / list / integer / string
signumber = "-" number / number
number = 1*DIGIT
CHAR = %x00-FF
DIGIT = "0" / "1" / "2" / "3" / "4" /
"5" / "6" / "7" / "8" / "9"
Source: BTP RFC
Installation
Using pip
pip install bendcode
Manual Installation
git clone https://github.com/sanketh95/BenDcode
cd BenDcode
python setup.py install
Usage
Decoding bencoded data is simple.
>>> import bendcode
>>> bendcode.decode('i123e')
123
>>> bendcode.decode('4:John')
'John'
>>> bendcode.decode('li234ei123ee')
[234, 123]
>>> bendcode.decode('d1:ai123e1:bi234ee')
{'a': 123, 'b': 234}
You can decode invidual types too !
>>> import bendcode
>>> bendcode.match_string('3:abc')
('abc', '')
>>> bendcode.match_int('i-123e')
(-123, '')
>>> bendcode.match_list('li123ee')
([123], '')
>>> bendcode.match_dict('d1:a1:bei123e')
({'a': 'b'}, 'i123e')
Note: The match_* series of functions return a tuple (first_possbile_match, remaining_unmatched_string)
Bendcode can encode too
>>> import bendcode
>>> bendcode.encode(123)
'i123e'
>>> bendcode.encode('John')
'4:John'
>>> bendcode.encode([123, 'bro'])
'li123e3:broe'
>>> bendcode.encode({'hello': 123})
'd5:helloi123ee'
>>> bendcode.encode(None)
''
You decide whether to raise an exception or not for any functions mentioned above by setting the fail_silently
parameter to True
or False
>>> import bendcode
>>> bendcode.match_string('abc')
(None, 'abc')
>>> bendcode.match_string('abc', fail_silently=False)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "bendcode\bendcode.py", line 39, in match_string
raise MalformedBencodeError('Failed to match string in ' + str(raw))
bendcode.exceptions.MalformedBencodeError: Failed to match string in abc
Tests
Run tests using the following code
>>> from bendcode import tests
>>> tests.run_tests()
..................................
----------------------------------------
Ran 34 tests in 0.015s
OK
Issues
If you find any bug, feel free to create an issue here.
License
BenDcode uses GNU v2 License. Read the terms of the license here.