Framework for extended message encoding
- helper classes for encoding/decoding messages - includes both old as well as new extended one (msgpack+zlib) - the classes are unused yet and are supposed to be for experimenting
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class BTFailure(Exception):
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pass
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@ -1,142 +0,0 @@
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# coding: utf-8
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# The contents of this file are subject to the BitTorrent Open Source License
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# Version 1.1 (the License). You may not copy or use this file, in either
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# source code or executable form, except in compliance with the License. You
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# may obtain a copy of the License at http://www.bittorrent.com/license/.
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#
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# Software distributed under the License is distributed on an AS IS basis,
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# WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
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# for the specific language governing rights and limitations under the
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# License.
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# Written by Petru Paler
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# Modifed by Peter Šurda
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from BTL import BTFailure
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def decode_int(x, f):
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f += 1
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newf = x.index('e', f)
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n = int(x[f:newf])
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if x[f] == '-':
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if x[f + 1] == '0':
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raise ValueError
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elif x[f] == '0' and newf != f+1:
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raise ValueError
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return (n, newf+1)
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def decode_string(x, f):
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colon = x.index(':', f)
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n = int(x[f:colon])
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if x[f] == '0' and colon != f+1:
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raise ValueError
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colon += 1
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return (x[colon:colon+n], colon+n)
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def decode_list(x, f):
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r, f = [], f+1
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while x[f] != 'e':
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v, f = decode_func[x[f]](x, f)
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r.append(v)
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return (r, f + 1)
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def decode_dict(x, f):
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r, f = {}, f+1
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while x[f] != 'e':
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k, f = decode_string(x, f)
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r[k], f = decode_func[x[f]](x, f)
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return (r, f + 1)
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decode_func = {}
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decode_func['l'] = decode_list
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decode_func['d'] = decode_dict
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decode_func['i'] = decode_int
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decode_func['0'] = decode_string
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decode_func['1'] = decode_string
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decode_func['2'] = decode_string
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decode_func['3'] = decode_string
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decode_func['4'] = decode_string
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decode_func['5'] = decode_string
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decode_func['6'] = decode_string
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decode_func['7'] = decode_string
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decode_func['8'] = decode_string
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decode_func['9'] = decode_string
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def bdecode(x):
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try:
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r, l = decode_func[x[0]](x, 0)
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except (IndexError, KeyError, ValueError):
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raise BTFailure("not a valid bencoded string")
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if l != len(x):
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raise BTFailure("invalid bencoded value (data after valid prefix)")
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return r
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from types import StringType, IntType, LongType, DictType, ListType, TupleType, UnicodeType, NoneType
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class Bencached(object):
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__slots__ = ['bencoded']
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def __init__(self, s):
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self.bencoded = s
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def encode_bencached(x,r):
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r.append(x.bencoded)
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def encode_int(x, r):
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r.extend(('i', str(x), 'e'))
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def encode_bool(x, r):
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if x:
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encode_int(1, r)
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else:
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encode_int(0, r)
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def encode_string(x, r):
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r.extend((str(len(x)), ':', x))
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def encode_unicode(x, r):
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raw = x.encode('utf8')
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r.extend((str(len(raw)), ':', raw))
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def encode_none(x, r):
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r.extend('0:')
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def encode_list(x, r):
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r.append('l')
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for i in x:
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encode_func[type(i)](i, r)
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r.append('e')
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def encode_dict(x,r):
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r.append('d')
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ilist = x.items()
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ilist.sort()
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for k, v in ilist:
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r.extend((str(len(k)), ':', k))
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encode_func[type(v)](v, r)
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r.append('e')
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encode_func = {}
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encode_func[Bencached] = encode_bencached
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encode_func[IntType] = encode_int
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encode_func[LongType] = encode_int
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encode_func[StringType] = encode_string
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encode_func[ListType] = encode_list
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encode_func[TupleType] = encode_list
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encode_func[DictType] = encode_dict
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encode_func[UnicodeType] = encode_unicode
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encode_func[NoneType] = encode_none
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try:
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from types import BooleanType
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encode_func[BooleanType] = encode_bool
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except ImportError:
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pass
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def bencode(x):
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r = []
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encode_func[type(x)](x, r)
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return ''.join(r)
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86
src/helper_msgcoding.py
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86
src/helper_msgcoding.py
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@ -0,0 +1,86 @@
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#!/usr/bin/python2.7
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import msgpack
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import zlib
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from debug import logger
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BITMESSAGE_ENCODING_IGNORE = 0
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BITMESSAGE_ENCODING_TRIVIAL = 1
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BITMESSAGE_ENCODING_SIMPLE = 2
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BITMESSAGE.ENCODING_EXTENDED = 3
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class MsgEncode(object):
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def __init__(self, message, encoding = BITMESSAGE_ENCODING_SIMPLE):
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self.data = None
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self.encoding = encoding
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self.length = 0
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if self.encoding == BITMESSAGE_ENCODING_EXTENDED:
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self.encodeExtended(message)
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elif self.encoding == BITMESSAGE_ENCODING_SIMPLE:
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self.encodeSimple(message)
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elif self.encoding == BITMESSAGE_ENCODING_TRIVIAL:
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self.encodeTrivial(message)
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def encodeExtended(self, message):
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try:
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self.data = zlib.compress(msgpack.dumps({"": "message", "subject": message['subject'], "message": ['body']}), 9)
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except zlib.error:
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logger.error ("Error compressing message")
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raise
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except msgpack.exceptions.PackException:
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logger.error ("Error msgpacking message")
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raise
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self.length = len(self.data)
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def encodeSimple(self, message):
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self.data = 'Subject:' + message['subject'] + '\n' + 'Body:' + message['body']
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self.length = len(self.data)
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def encodeTrivial(self, message):
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self.data = message['body']
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self.length = len(self.data)
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class MsgDecode(object):
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def __init__(self, encoding, data):
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self.encoding = encoding
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if self.encoding == BITMESSAGE_ENCODING_EXTENDED:
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self.decodeExtended(data)
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elif self.encoding in [BITMESSAGE_ENCODING_SIMPLE, BITMESSAGE_ENCODING_TRIVIAL]:
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self.decodeSimple(data)
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return
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def decodeExtended(self, data):
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try:
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tmp = msgpack.loads(zlib.decompress(data))
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except zlib.error:
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logger.error ("Error decompressing message")
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raise
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except (msgpack.exceptions.UnpackException,
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msgpack.exceptions.ExtraData):
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logger.error ("Error msgunpacking message")
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raise
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try:
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if tmp[""] == "message":
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self.body = tmp["body"]
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self.subject = tmp["subject"]
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except:
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logger.error ("Malformed message")
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raise
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def decodeSimple(self, data):
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bodyPositionIndex = string.find(data, '\nBody:')
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if bodyPositionIndex > 1:
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subject = message[8:bodyPositionIndex]
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# Only save and show the first 500 characters of the subject.
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# Any more is probably an attack.
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subject = subject[:500]
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body = message[bodyPositionIndex + 6:]
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else:
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subject = ''
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body = message
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# Throw away any extra lines (headers) after the subject.
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if subject:
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subject = subject.splitlines()[0]
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self.subject = subject
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self.message = body
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