Zlib: correct checksum but error decompressing

Andre andre.cohen at gmail.com
Wed Aug 26 16:19:42 CEST 2009

I have been trying to solve this issue for a while now. I receive data
from a TCP connection which is compressed. I know the correct checksum
for the data and both the client and server generate the same
checksum. However, in Python when it comes to decompressing the data I
get the exception: "Error -5 while decompressing data"! I would assume
that if the string in python is equivalent to the correct checksum
than the decompress function should also work on the same string, but
that's clearly not the case.

# convert data to a byte array
data = array('b', raw_data)
# print checksum for visual inspection
print zlib.crc32(data.tostring())
# try to decompress, but fails!
str = zlib.decompress(data.tostring())

Does anyone know what's going on?

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