torrent_to_magnet.py

import sys
import bencode
import hashlib
import base64
import urllib

torrent_file = sys.argv[1]
torrent = open(torrent_file, 'r').read()
metadata = bencode.bdecode(torrent)

hashcontents = bencode.bencode(metadata['info'])
digest = hashlib.sha1(hashcontents).digest()
b32hash = base64.b32encode(digest)
print "magnet:?xt=urn:btih:%s" %  b32hash

params = {
  'xt': 'urn:btih:%s' % b32hash,
  'dn': metadata['info']['name'],
  'tr': metadata['announce'],
  'xl': metadata['info']['length']}

paramstr = urllib.urlencode(params)
magneturi = 'magnet:?%s' % paramstr
print magneturi