Re: [libmicrohttpd] Parsing multipart/formdata

[Markus Doppelbauer]

Hi Christian,

No problem. Just a corner case as you say.

Thanks a lot for your answer.

Best wishes

-------- Weitergeleitete Nachricht --------

Von: Christian Grothoff <address@hidden>

Antwort an: libmicrohttpd development and user mailinglist <address@hidden>

An: address@hidden

Betreff: Re: [libmicrohttpd] Parsing multipart/formdata

Datum: Tue, 21 Apr 2020 16:25:53 +0200

Hi Markus,

Let me get this straight:

The scenario you are concerned with is to distinguish the case that

there are possibly two variables with *identical* key / content-type

*values* and the first one has an 'empty' value, and the second case is

that there is just one value and you got called with size=0 merely

because of 'unfortunate' network traffic. Is that right?

If so, I don't think the current API allows you to _reliably_

distinguish those two cases (cmp'ing pointers is an unreliable hack, as

you say). It's an interesting corner case, which we may want to document

and/or fix in the v2.0 API -- unless someone has a good proposal for how

to do address this case in a binary-API compatible way.

Happy hacking!

Christian

On 4/21/20 4:17 PM, Markus Doppelbauer wrote:

Hello,

Is there a reliable way to detect 'continution' in 'MHD_PostDataIterator()'?

To detect the beginning of a new variable I have tested: 'off == 0'.

But this is not reliable. It is a rare case but sometimes the iterator

stops right

before the first content-byte (if helpful I will provide a testcase):

first call:

MHD_PostDataIterator( cls, kind=MHD_POSTDATA_KIND, key="upload-name",

filename="video.mp4", content_type="video/mp4", transfer_encoding=nullptr,

data="" off=0, size=0 );

second call:

MHD_PostDataIterator( cls, kind=MHD_POSTDATA_KIND, key="upload-name",

filename="video.mp4", content_type="video/mp4", transfer_encoding=nullptr,

data="" off=0, size=64724 );

Pointer comparision of 'key', 'filename' and 'content_type' works - but

is also not 100% reliable.

'malloc()' could provide the same address.

Thanks a lot

Markus