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Hi Christian,
You're right, I am walking through the URL to extract the keys and values.
I wrote this 5 years ago and I must have misunderstood the mechanism at the time. I still don't quite understand why the strlen method fails for escaped characters.
I guess I need to rewrite it and call MHD_get_connection_values with a callback to handle all possible name/value pairs. This sounds like a better option than multiple calls to MHD_lookup_connection_value, as there are lots of key/value pairs which are optionally present in the API URL.
Cheers
David
---------------------------------------------------------------------- >Hi David,
>I'm a bit confused as to how you are accessing the 'camname' field, or rather, how >you 'skip' to the next field. I suspect you're badly violating the API, but I'm not sure.
>What it sounds to me like is that you're going after 'camname' by something like:
>const char *camname = url[strlen(url)+1];
>const char *camvalue = camname[strlen(camname)+1];
>const char *nextname = camvalue[strlen(camvalue)+1]; // this fails ...
>const char *nextvalue = nextname[strlen(nextname)+1];
>where 'url' was the respective argument of the MHD_AccessHandlerCallback. That kind-of works, modulo escaping, as you can follow the key-value pairs by walking through memory like this if there is no escaping, but is excessively ugly and not actually guaranteed to work by MHD's API (it just happens to work...).
>What you should be doing is using either the MHD_lookup_connection_value() or MHD_get_connection_values() functions:
>const char *camvalue = MHD_lookup_connection_value (connection, MHD_GET_ARGUMENT_KIND, "camname");
>const char *nextvalue = MHD_lookup_connection_value (connection, MHD_GET_ARGUMENT_KIND, "nextname");
>So are you actually using MHD_lookup_connection_value(), or walking illicitly over MHD's internal buffers? :-) Happy hacking! Christian On 09/22/2015 06:47 PM, address@hidden wrote: >
----------------------------------------------------------------------
Hi there,
> > I've been using libmicrohttpd for a number of years now, but I have just
> found a basic problem with my URL parser when I receive a URL with > escaped characters. In my webpage I am using the _javascript_ function, > encodeURIComponent() to help produce the escaped URL, something like this:-
> > setcamparam.cgi?camname=cam&fred, where "cam&fred" is the name string
> > This is converted into the following url > > setcamparam.cgi?camname=cam%26fred > > which is fine. > > The problem is in my http_access_callback, when I receive this url, I > seem to receive "cam&fred" unescaped, but the length of the field I need
> to skip in the url is 2 more than the string length. If there are more
> escaped characters in the url, then the difference is even higher.
> > How do I know how many escaped characters have been unescaped so that I
> can parse the url correctly and skip to the next field? I'm just using
> strlen() to skip over each field.
> > Best regards
> > David
> >
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