Python: Inflate and Deflate implementations

You can still use the zlib module to inflate/deflate data. The gzip module uses it internally, but adds a file-header to make it into a gzip-file. Looking at the gzip.py file, something like this could work:

import zlib

def deflate(data, compresslevel=9):
    compress = zlib.compressobj(
            compresslevel,        # level: 0-9
            zlib.DEFLATED,        # method: must be DEFLATED
            -zlib.MAX_WBITS,      # window size in bits:
                                  #   -15..-8: negate, suppress header
                                  #   8..15: normal
                                  #   16..30: subtract 16, gzip header
            zlib.DEF_MEM_LEVEL,   # mem level: 1..8/9
            0                     # strategy:
                                  #   0 = Z_DEFAULT_STRATEGY
                                  #   1 = Z_FILTERED
                                  #   2 = Z_HUFFMAN_ONLY
                                  #   3 = Z_RLE
                                  #   4 = Z_FIXED
    )
    deflated = compress.compress(data)
    deflated += compress.flush()
    return deflated

def inflate(data):
    decompress = zlib.decompressobj(
            -zlib.MAX_WBITS  # see above
    )
    inflated = decompress.decompress(data)
    inflated += decompress.flush()
    return inflated

I don’t know if this corresponds exactly to whatever your server requires, but those two functions are able to round-trip any data I tried.

The parameters maps directly to what is passed to the zlib library functions.

Python ⇒ C
zlib.compressobj(...) ⇒ deflateInit(...)
compressobj.compress(...) ⇒ deflate(...)
zlib.decompressobj(...) ⇒ inflateInit(...)
decompressobj.decompress(...) ⇒ inflate(...)

The constructors create the structure and populate it with default values, and pass it along to the init-functions.
The compress/decompress methods update the structure and pass it to inflate/deflate.