[libmicrohttpd] Missing Feature: Custom HTTP decoding

[Gerrit Telkamp]

I would like to know your opinion about a feature, we are currently missing in 
libmicrohttpd.

It concerns the URL decoding, implemented in function MHD_http_unescape() (file 
"internal.c").
This function escapes all characters encoded as %HH into a single byte. It is used e.g. 
to convert an URL like "http://hello%20world.com";, received from the browser.

If you are using libmicrohttpd for an AJAX application, MHD_http_unescape() will not be enough. The JavaScript code 
running in the browser might send a string containing differnt characters that those used for URLs. Some browsers are 
sending 16 bit codes, encoded as "%uXXXX" (see alsohttp://www.w3.org/International/O-URL-code.html). And not 
all browsers running on all operation systems are using the same characzer encoding - we have seen that some browsers 
are using ISO8859-1, others are using UTF-8. A German umlaut "ü" for example is encoded as "%FC" 
and not as "%C3%BC" (UTF-8).

A good solution might be to support a custom-specific character decoder, that 
is called by libmicrohttpd instead of its internal MHD_http_unescape(). This 
custom-specific decoder should be provided as a call-back method by the user. 
If it is not defined, the internal
MHD_http_unescape() will be used.

The decoder should get a pointer to the input butter, and might return a new 
pointer to the output buffer. This would be useful if the decoded characters in 
the output buffer need more memory space than what is available in the input 
buffer.

We is your opinion?

Best regards

Gerrit.