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

bencode/BTL.py

@@ -1,2 +0,0 @@
-class BTFailure(Exception):
-    pass

bencode/__init__.py

@@ -1,142 +0,0 @@
-# coding: utf-8
-# 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
-# Modifed by Peter Šurda
-
-from BTL import BTFailure
-
-
-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, UnicodeType, NoneType
-
-
-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_unicode(x, r):
-    raw = x.encode('utf8')
-    r.extend((str(len(raw)), ':', raw))
-
-def encode_none(x, r):
-    r.extend('0:')
-
-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
-encode_func[UnicodeType] = encode_unicode
-encode_func[NoneType] = encode_none
-
-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)

src/helper_msgcoding.py

@@ -0,0 +1,86 @@
+#!/usr/bin/python2.7
+
+import msgpack
+import zlib
+
+from debug import logger
+
+BITMESSAGE_ENCODING_IGNORE = 0
+BITMESSAGE_ENCODING_TRIVIAL = 1
+BITMESSAGE_ENCODING_SIMPLE = 2
+BITMESSAGE.ENCODING_EXTENDED = 3
+
+class MsgEncode(object):
+    def __init__(self, message, encoding = BITMESSAGE_ENCODING_SIMPLE):
+        self.data = None
+        self.encoding = encoding
+        self.length = 0
+        if self.encoding == BITMESSAGE_ENCODING_EXTENDED:
+            self.encodeExtended(message)
+        elif self.encoding == BITMESSAGE_ENCODING_SIMPLE:
+            self.encodeSimple(message)
+        elif self.encoding == BITMESSAGE_ENCODING_TRIVIAL:
+            self.encodeTrivial(message)
+
+    def encodeExtended(self, message):
+        try:
+            self.data = zlib.compress(msgpack.dumps({"": "message", "subject": message['subject'], "message": ['body']}), 9)
+        except zlib.error:
+            logger.error ("Error compressing message")
+            raise
+        except msgpack.exceptions.PackException:
+            logger.error ("Error msgpacking message")
+            raise
+        self.length = len(self.data)
+
+    def encodeSimple(self, message):
+        self.data = 'Subject:' + message['subject'] + '\n' + 'Body:' + message['body']
+        self.length = len(self.data)
+
+    def encodeTrivial(self, message):
+        self.data = message['body']
+        self.length = len(self.data)
+
+class MsgDecode(object):
+    def __init__(self, encoding, data):
+        self.encoding = encoding
+        if self.encoding == BITMESSAGE_ENCODING_EXTENDED:
+            self.decodeExtended(data)
+        elif self.encoding in [BITMESSAGE_ENCODING_SIMPLE, BITMESSAGE_ENCODING_TRIVIAL]:
+            self.decodeSimple(data)
+        return
+
+    def decodeExtended(self, data):
+        try:
+            tmp = msgpack.loads(zlib.decompress(data))
+        except zlib.error:
+            logger.error ("Error decompressing message")
+            raise
+        except (msgpack.exceptions.UnpackException,
+                msgpack.exceptions.ExtraData):
+            logger.error ("Error msgunpacking message")
+            raise
+        try:
+            if tmp[""] == "message":
+                self.body = tmp["body"]
+                self.subject = tmp["subject"]
+        except:
+            logger.error ("Malformed message")
+            raise
+
+    def decodeSimple(self, data):
+        bodyPositionIndex = string.find(data, '\nBody:')
+        if bodyPositionIndex > 1:
+            subject = message[8:bodyPositionIndex]
+            # Only save and show the first 500 characters of the subject.
+            # Any more is probably an attack.
+            subject = subject[:500]
+            body = message[bodyPositionIndex + 6:]
+        else:
+            subject = ''
+            body = message
+        # Throw away any extra lines (headers) after the subject.
+        if subject:
+            subject = subject.splitlines()[0]
+        self.subject = subject
+        self.message = body