def decode_int(x, f): f += 1 newf = x.index('e', f) try: n = int(x[f:newf]) except (OverflowError, ValueError): n = long(x[f:newf]) if x[f] == '-': if x[f + 1] == '0': raise ValueError elif x[f] == '0' and newf != f+1: raise ValueError return (n, newf+1) def decode_string(x, f): colon = x.index(':', f) try: n = int(x[f:colon]) except (OverflowError, ValueError): n = long(x[f:colon]) if x[f] == '0' and colon != f+1: raise ValueError colon += 1 return (x[colon:colon+n], colon+n) def decode_list(x, f): r, f = [], f+1 while x[f] != 'e': v, f = decode_func[x[f]](x, f) r.append(v) return (r, f + 1) def decode_dict(x, f): r, f = {}, f+1 lastkey = None while x[f] != 'e': k, f = decode_string(x, f) if lastkey >= k: raise ValueError lastkey = k r[k], f = decode_func[x[f]](x, f) return (r, f + 1) decode_func = {} decode_func['l'] = decode_list decode_func['d'] = decode_dict decode_func['i'] = decode_int decode_func['0'] = decode_string decode_func['1'] = decode_string decode_func['2'] = decode_string decode_func['3'] = decode_string decode_func['4'] = decode_string decode_func['5'] = decode_string decode_func['6'] = decode_string decode_func['7'] = decode_string decode_func['8'] = decode_string decode_func['9'] = decode_string def bdecode(x): try: r, l = decode_func[x[0]](x, 0) except (IndexError, KeyError): raise ValueError if l != len(x): raise ValueError return r def test_bdecode(): try: bdecode('0:0:') assert 0 except ValueError: pass try: bdecode('ie') assert 0 except ValueError: pass try: bdecode('i341foo382e') assert 0 except ValueError: pass assert bdecode('i4e') == 4L assert bdecode('i0e') == 0L assert bdecode('i123456789e') == 123456789L assert bdecode('i-10e') == -10L try: bdecode('i-0e') assert 0 except ValueError: pass try: bdecode('i123') assert 0 except ValueError: pass try: bdecode('') assert 0 except ValueError: pass try: bdecode('i6easd') assert 0 except ValueError: pass try: bdecode('35208734823ljdahflajhdf') assert 0 except ValueError: pass try: bdecode('2:abfdjslhfld') assert 0 except ValueError: pass assert bdecode('0:') == '' assert bdecode('3:abc') == 'abc' assert bdecode('10:1234567890') == '1234567890' try: bdecode('02:xy') assert 0 except ValueError: pass try: bdecode('l') assert 0 except ValueError: pass assert bdecode('le') == [] try: bdecode('leanfdldjfh') assert 0 except ValueError: pass assert bdecode('l0:0:0:e') == ['', '', ''] try: bdecode('relwjhrlewjh') assert 0 except ValueError: pass assert bdecode('li1ei2ei3ee') == [1, 2, 3] assert bdecode('l3:asd2:xye') == ['asd', 'xy'] assert bdecode('ll5:Alice3:Bobeli2ei3eee') == [['Alice', 'Bob'], [2, 3]] try: bdecode('d') assert 0 except ValueError: pass try: bdecode('defoobar') assert 0 except ValueError: pass assert bdecode('de') == {} assert bdecode('d3:agei25e4:eyes4:bluee') == {'age': 25, 'eyes': 'blue'} assert bdecode('d8:spam.mp3d6:author5:Alice6:lengthi100000eee') == {'spam.mp3': {'author': 'Alice', 'length': 100000}} try: bdecode('d3:fooe') assert 0 except ValueError: pass try: bdecode('di1e0:e') assert 0 except ValueError: pass try: bdecode('d1:b0:1:a0:e') assert 0 except ValueError: pass try: bdecode('d1:a0:1:a0:e') assert 0 except ValueError: pass try: bdecode('i03e') assert 0 except ValueError: pass try: bdecode('l01:ae') assert 0 except ValueError: pass try: bdecode('9999:x') assert 0 except ValueError: pass try: bdecode('l0:') assert 0 except ValueError: pass try: bdecode('d0:0:') assert 0 except ValueError: pass try: bdecode('d0:') assert 0 except ValueError: pass try: bdecode('00:') assert 0 except ValueError: pass try: bdecode('l-3:e') assert 0 except ValueError: pass try: bdecode('i-03e') assert 0 except ValueError: pass bdecode('d0:i3ee') from types import StringType, UnicodeType, IntType, LongType, DictType, ListType, TupleType class Bencached(object): __slots__ = ['bencoded'] def __init__(self, s): self.bencoded = s def encode_bencached(x,r): r.append(x.bencoded) def encode_int(x, r): r.extend(('i', str(x), 'e')) def encode_string(x, r): r.extend((str(len(x)), ':', x)) def encode_list(x, r): r.append('l') for i in x: encode_func[type(i)](i, r) r.append('e') def encode_dict(x,r): r.append('d') ilist = x.items() ilist.sort() for k, v in ilist: r.extend((str(len(k)), ':', k)) encode_func[type(v)](v, r) r.append('e') encode_func = {} encode_func[type(Bencached(0))] = encode_bencached encode_func[IntType] = encode_int encode_func[LongType] = encode_int encode_func[StringType] = encode_string encode_func[UnicodeType] = encode_string encode_func[ListType] = encode_list encode_func[TupleType] = encode_list encode_func[DictType] = encode_dict try: from types import BooleanType encode_func[BooleanType] = encode_int except ImportError: pass def bencode(x): r = [] encode_func[type(x)](x, r) return ''.join(r) def test_bencode(): assert bencode(4) == 'i4e' assert bencode(0) == 'i0e' assert bencode(-10) == 'i-10e' assert bencode(12345678901234567890L) == 'i12345678901234567890e' assert bencode('') == '0:' assert bencode('abc') == '3:abc' assert bencode('1234567890') == '10:1234567890' assert bencode([]) == 'le' assert bencode([1, 2, 3]) == 'li1ei2ei3ee' assert bencode([['Alice', 'Bob'], [2, 3]]) == 'll5:Alice3:Bobeli2ei3eee' assert bencode({}) == 'de' assert bencode({'age': 25, 'eyes': 'blue'}) == 'd3:agei25e4:eyes4:bluee' assert bencode({'spam.mp3': {'author': 'Alice', 'length': 100000}}) == 'd8:spam.mp3d6:author5:Alice6:lengthi100000eee' assert bencode(Bencached(bencode(3))) == 'i3e' try: bencode({1: 'foo'}) except TypeError: return assert 0 try: import psyco psyco.bind(bdecode) psyco.bind(bencode) except ImportError: pass #test_bencode() #test_bdecode()