PHP which compression function has equal output like mod_deflate?

Question

I tried:

gzencode($contents, 9, FORCE_DEFLATE)
gzdeflate...
zlib_encode($contents, -15);// RFC 1951 - raw deflate
zlib_encode($contents, 15);// RFC 1950 - zlib
<         


        

Answer 1

PHP's gzcompress(). The use of the word "deflate" in the HTTP specification and content encoding is a misnomer. It really means zlib, which is a zlib wrapper around raw deflate data. gzcompress() produces zlib-wrapped deflate data.

From the HTTP 1.1 specification:

deflate: The "zlib" format defined in RFC 1950 [31] in combination with the "deflate" compression mechanism described in RFC 1951 [29].

So HTTP "deflate" == zlib. HTTP "deflate" != deflate.

For reference, gzencode() produces gzip-wrapped deflate data, and gzdeflate() produces raw, unwrapped deflate data.