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Author lloyd
Recipients lloyd
Date 2007-11-29.17:15:11
SpamBayes Score 0.10931212
Marked as misclassified No
Message-id <1196356512.02.0.767950905039.issue1523@psf.upfronthosting.co.za>
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Content
The XDR format requires integers to fit into 4 byte values. However (at
least on x86-64) xdrlib will silently accept (and truncate) values
larger than this (up to 2**64-1). Taking a (very brief) look at the
xdrlib code, it appears this is actually a problem in the struct module,
but I don't have the time (or interest) to trace through the _struct
module code.

An example on an x86-64 machine (Python 2.4.3) of encoding 2**32 (which
will not fit in an XDR field) being silently truncated:

$ ./xdr.py 
4294967296 -> 00000000 -> 0

An example of struct itself not detecting overflow:

>>> struct.pack("!I", 2**32)
'\x00\x00\x00\x00'

struct.pack will only throw an overflow error if a value >= 2**64 is
used, even if it is encoding into a field that is much smaller.
Files
File name Uploaded
xdr.py lloyd, 2007-11-29.17:15:11
History
Date User Action Args
2007-11-29 17:15:12lloydsetspambayes_score: 0.109312 -> 0.10931212
recipients: + lloyd
2007-11-29 17:15:12lloydsetspambayes_score: 0.109312 -> 0.109312
messageid: <1196356512.02.0.767950905039.issue1523@psf.upfronthosting.co.za>
2007-11-29 17:15:11lloydlinkissue1523 messages
2007-11-29 17:15:11lloydcreate