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using id() to generate a 32-bit integer fails in 64-bit environment #14

Closed GoogleCodeExporter closed 9 years ago

GoogleCodeExporter commented 9 years ago 
with a 64-bit build of python, id() results often exceed 2**32, which causes 
structure.pack to be unhappy.

Found this in the srvsvcserver code, but maybe it's elsewhere.. Here's what I 
did to fix (not bulletproof, but probably safe?):

Index: impacket/dcerpc/srvsvcserver.py
===================================================================
--- impacket/dcerpc/srvsvcserver.py (revision 714)
+++ impacket/dcerpc/srvsvcserver.py (working copy)
@@ -212,6 +212,9 @@
 import ConfigParser
 import struct

+def _get_id(o):
+  return id(o) & 0xffffffff
+
 class SRVSVCServer(DCERPCServer):
     def __init__(self):
         DCERPCServer.__init__(self)
@@ -243,9 +246,9 @@
        answer = srvsvc.SRVSVCSwitchpShareInfo2()
        answer['Level']      = 1
        answer['InfoStruct'] = srvsvc.SRVSVCShareInfo1()
-       answer['InfoStruct']['pNetName'] = id(share)
+       answer['InfoStruct']['pNetName'] = _get_id(share)
        answer['InfoStruct']['Type']     = int(share['share type'])
-       answer['InfoStruct']['pRemark']  = id(share)+1
+       answer['InfoStruct']['pRemark']  = _get_id(share)+1
        answer = str(answer)
        netName = srvsvc.NDRString()
        remark  = srvsvc.NDRString()
@@ -276,9 +279,9 @@
        answer = str(shareEnum) 
        for i in self.__shares:
           shareInfo = srvsvc.SRVSVCShareInfo1()
-          shareInfo['pNetName'] = id(i)
+          shareInfo['pNetName'] = _get_id(i)
           shareInfo['Type']     = int(self.__shares[i]['share type'])
-          shareInfo['pRemark']  = id(i)+1
+          shareInfo['pRemark']  = _get_id(i)+1
           answer += str(shareInfo)

        for i in self.__shares:

Original issue reported on code.google.com by bryanbu...@gmail.com on 10 Sep 2012 at 5:14

GoogleCodeExporter commented 9 years ago 
Wow.. nice catch Bryan.. Can you send me an output of the error you receive?

Original comment by bet...@gmail.com on 10 Sep 2012 at 5:26

GoogleCodeExporter commented 9 years ago 
caught exception: ("'L' format requires 0 <= number <= 4294967295", "When 
packing field 'pNetName | <L | 4410144592' in 
impacket.dcerpc.srvsvc.SRVSVCShareInfo1")

Original comment by bryanbu...@gmail.com on 10 Sep 2012 at 5:28

GoogleCodeExporter commented 9 years ago 
here's a random test in my environment:

In [1]: x = id('test')

In [2]: x
Out[2]: 4341761680

In [3]: x > 2**32
Out[3]: True

In [4]: x - 2**32
Out[4]: 46794384

In [5]: import struct

In [6]: struct.pack('>L', x)
---------------------------------------------------------------------------
error                                     Traceback (most recent call last)
<ipython-input-6-80b596231688> in <module>()
----> 1 struct.pack('>L', x)

error: 'L' format requires 0 <= number <= 4294967295

Original comment by bryanbu...@gmail.com on 10 Sep 2012 at 5:29

GoogleCodeExporter commented 9 years ago 
Great...

Yep.. your fix indeed solves the problem.. but only if the definition of the 
structure field is '<L' (otherwise the mask should be changed).. stick to that 
fix.. and let me review the other parts of the library when id() is used and 
see if I can come up with something more general, that can check the 
structure's definition as well.

We had a similar issue in the past in structure (it uses id() for some stuff 
too..)...

graciass!
bto

Original comment by bet...@gmail.com on 10 Sep 2012 at 5:33

GoogleCodeExporter commented 9 years ago 
Okey.. 

There weren't many other instances of the same problem.. (just a few in 
svcctl). Fixed in http://code.google.com/p/impacket/source/detail?r=715

Let me know if it works...

thanks bryan!

Original comment by bet...@gmail.com on 10 Sep 2012 at 7:41