theamm / yabencode

Yet Another Bencode module

YABEncode - Yet Another Bencode module

An implementation of bencoding/bdecoding in Python 3, with somewhat descriptive Exceptions for decode errors. Also includes a command-line tool for decoding and pretty-printing bencoded data!

Installing

To install from PyPI:

pip install yabencode

---

Usage:

In Python...

import yabencode
# bencode supports dicts, lists, ints and strings (bytestrings)
yabencode.encode({'foo':'baz', 'list':['eggs', 'spam', 'bacon']})
# Input can be string, bytes or a file object
yabencode.decode(b'd3:foo3:baz4:listl4:eggs4:spam5:baconee')

try:
    # Malformed data, 'spam' is missing an 'a'
    yabencode.decode(b'd3:foo3:baz4:listl4:eggs4:spm5:baconee')
except yabencode.MalformedBencodeException as e:
    print(e)
    # Unexpected data type (b':') at position 31 (0x1F hex)

try:
    # Bencode does not support floats
    yabencode.encode({'float':3.14})
except yabencode.BencodeException as e:
    print(e)
    # Unsupported type <class 'float'>

or with the command-line tool:

$ yabencode -h
usage: yabencode [-h] [-t KEY] [-r] FILE

Bdecode a file/standard input and pretty-print the resulting data

positional arguments:
  FILE                  Input file. Use - for stdin

optional arguments:
  -h, --help            show this help message and exit
  -t KEY, --truncate KEY
                        Truncate values under given key. May be repeated for
                        multiple values
  -r, --raw             Raw keys - do not decode dictionary keys

$ # The 'pieces'-bytestring is rather long, so let's truncate it
$ yabencode -t pieces ubuntu-17.04-desktop-amd64.iso.torrent
{'announce': b'http://torrent.ubuntu.com:6969/announce',
 'announce-list': [[b'http://torrent.ubuntu.com:6969/announce'],
                   [b'http://ipv6.torrent.ubuntu.com:6969/announce']],
 'comment': b'Ubuntu CD releases.ubuntu.com',
 'creation date': 1492077159,
 'info': {'length': 1609039872,
          'name': b'ubuntu-17.04-desktop-amd64.iso',
          'piece length': 524288,
          'pieces': '<truncated>'}}

$ # Reading bytes from stdin (using -r to not decode the keys)
$ curl -s 'http://torrent.ubuntu.com:6969/scrape?info_hash=%59%06%67%69%b9%ad%42%da%2e%50%86%11%c3%3d%7c%44%80%b3%85%7b' | yabencode -r -
{b'files': {b'Y\x06gi\xb9\xadB\xda.P\x86\x11\xc3=|D\x80\xb3\x85{': {b'complete': 3473,
                                                                    b'downloaded': 33029,
                                                                    b'incomplete': 102,
                                                                    b'name': b'ubuntu-17.04-desktop-amd64.iso'}}}