# The contents of this file are subject to the BitTorrent Open Source License # Version 1.1 (the License). You may not copy or use this file, in either # source code or executable form, except in compliance with the License. You # may obtain a copy of the License at http://www.bittorrent.com/license/. # # Software distributed under the License is distributed on an AS IS basis, # WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License # for the specific language governing rights and limitations under the # License. # Written by Petru Paler class BTFailure(Exception): pass def decode_int(x, f): f += 1 newf = x.index('e', f) n = int(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) n = int(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 while x[f] != 'e': k, f = decode_string(x, f) 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, ValueError): raise BTFailure("not a valid bencoded string") if l != len(x): raise BTFailure("invalid bencoded value (data after valid prefix)") return r from types import StringType, 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_bool(x, r): if x: encode_int(1, r) else: encode_int(0, r) 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[Bencached] = encode_bencached encode_func[IntType] = encode_int encode_func[LongType] = encode_int encode_func[StringType] = 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_bool except ImportError: pass def bencode(x): r = [] encode_func[type(x)](x, r) return ''.join(r)