A little remark about gzip and mirc. Gzip is an encapsulation of compressed data. This compressed part is exactly what mirc reads and writes with $compress() $decompress(), except that it uses zlib deflate encapsulation. Note: zlib/deflate encapsulation is 6 bytes, and gzip encapsulation is 18 bytes (with no filename)
Both formats, gzip and deflate, use encapsulation with checksum verification (ADLER32 for deflate, and CRC32 for gzip). These methods are incompatible, so you can't simply dress gzip as deflate since you can't convert CRC32 to ADLER32. I've debugged mirc, and have found the location where a call to ADLER32 is done. By deactivating it I can feed $decompress() with deflate data or with gzip dressed as deflate. For gzip, I can then verify the CRC32 of the decompressed data. But for native deflate data, since $adler32() doesn't exist, verification is definitively lost.
Now, why mirc doesn't support gzip encoding?
mirc uses its own embedded version of the zlib library. This library natively supports both formats (encoding and decoding in gzip and zlib/deflate format). It should be easy to enable gzip awareness in mirc.
