[libmicrohttpd] unable to respond before reading entire incoming payload

[Ken Zangelin]

Hi,

I am provoking a request for 'Payload too large' for our MHD server, by 
using curl sending a short request (~25 bytes) but adding a Content-Len 
header of a lot more (2 megabytes).

In our case the maximum payload we accept is a megabyte.

So, in the mhd callback routines we detect the  Content-Len header (and 
probably read the 25 bytes of payload as well, haven't checked) and when 
we see that the Content-Len header value is beyond our allowed max size, 
we want to return a response with a payload telling the user about the 
error.

We've tried to set the upload_data_size pointer to point to ZERO, 
awaiting the last call to the callback, but it never comes.

Probably due to that MHD still believes there is more data to read.

Using MHD_OPTION_CONNECTION_TIMEOUT, at least the connection resets 
instead of hangs, but ... we'd like to send that response ...

Is there any way to accomplish what we want?

Thank you!

/KZ