Decompression limit

- there is now a configurable decompression limit, default at
1MB. Oversize messages are trated as if they never arrived,
just a log entry

src/class_objectProcessor.py

@@ -28,7 +28,6 @@ import tr
 from debug import logger
 import l10n
 
-
 class objectProcessor(threading.Thread):
     """
     The objectProcessor thread, of which there is only one, receives network
@@ -71,6 +70,8 @@ class objectProcessor(threading.Thread):
                     pass
                 else:
                     logger.critical('Error! Bug! The class_objectProcessor was passed an object type it doesn\'t recognize: %s' % str(objectType))
+            except helper_msgcoding.DecompressionSizeException as e:
+                logger.error("The object is too big after decompression (stopped decompressing at %ib, your configured limit %ib). Ignoring", e.size, BMConfigParser().safeGetInt("zlib", "maxsize"))
             except varintDecodeError as e:
                 logger.debug("There was a problem with a varint while processing an object. Some details: %s" % e)
             except Exception as e:

src/helper_msgcoding.py

@@ -7,6 +7,7 @@ except ImportError:
 import string
 import zlib
 
+from bmconfigparser import BMConfigParser
 import shared
 from debug import logger
 import messagetypes
@@ -17,6 +18,10 @@ BITMESSAGE_ENCODING_TRIVIAL = 1
 BITMESSAGE_ENCODING_SIMPLE = 2
 BITMESSAGE_ENCODING_EXTENDED = 3
 
+class DecompressionSizeException(Exception):
+    def __init__(self, size):
+        self.size = size
+
 
 class MsgEncode(object):
     def __init__(self, message, encoding=BITMESSAGE_ENCODING_SIMPLE):
@@ -65,11 +70,24 @@ class MsgDecode(object):
             self.subject = _translate("MsgDecode", "Unknown encoding")
 
     def decodeExtended(self, data):
+        dc = zlib.decompressobj()
+        tmp = ""
+        while len(tmp) <= BMConfigParser().safeGetInt("zlib", "maxsize"):
+            try:
+                got = dc.decompress(data, BMConfigParser().safeGetInt("zlib", "maxsize") + 1 - len(tmp))
+                # EOF
+                if got == "":
+                    break
+                tmp += got
+                data = dc.unconsumed_tail
+            except zlib.error:
+                logger.error("Error decompressing message")
+                raise
+        else:
+            raise DecompressionSizeException(len(tmp))
+
         try:
-            tmp = msgpack.loads(zlib.decompress(data))
+            tmp = msgpack.loads(tmp)
-        except zlib.error:
-            logger.error("Error decompressing message")
-            raise
         except (msgpack.exceptions.UnpackException,
                 msgpack.exceptions.ExtraData):
             logger.error("Error msgunpacking message")