Callback getting max 255 bytes of data from TEXTAREA in FORM

jaypdx · Post by **jaypdx** » Wed Dec 23, 2020 7:33 pm

I have a callback receiving data from a textarea in a form but I'm only getting the first 255 bytes of the form data in my callback handler.

My html looks like this:

Code: Select all

<body>
	<form action="configform.html" method=post>
		<fieldset>
			<legend>Board setup file:</legend>
			<h2>Config file:</h2>
			<textarea id="text" maxlength="2500" name="configtext" rows="15" cols="80"><!--VARIABLE ConfigText --></textarea>
			<br />
			<input type="submit" name="load" value="Load from SD">
			<input type="submit" name="check" value="Check syntax">
			<input type="submit" name="save" value="Save to SD">
			<br />
			<h2>Errors:</h2>
			<textarea readonly id="text" name="configerr" rows="15" cols="80"><!--VARIABLE ConfigErr --></textarea>
			<h2><!--FUNCTIONCALL ShowSDCardStatus --></h2>
		</fieldset>
	</form>
	<br />
	<a href="index.html">Return to Main Page</a>
</body>

and my callback handler looks like this:

Code: Select all

void configFormPostCallBack(int sock, PostEvents event, const char * pName, const char * pValue)
{
    // Received a call back with an event, check for event type
    switch (event)
    {
    case eStartingPost:     // Called at the beginning of the post before any data is sent
    	iprintf("configFormPostCallBack:eStartingPost: pName=[%s]\n", pName);
        break;

    case eVariable:     // Called once for each variable in the form
    	iprintf("configFormPostCallBack:eVariable: pName=[%s]\n", pName);
        if (strcmp("configtext", pName) == 0) {
            iprintf("strlen(pValue)=%d\n", strlen(pValue));
            strcpy(ConfigText, pValue);
            iprintf("ConfigText: (%d bytes):\n%s\n", strlen(ConfigText), ConfigText);
            dump_buff(pValue);
        }
        .
        .
        .
}

// Create a global static post handling object that responds to the specified html page.
// A separate post handler can be created for each form in your application.
HtmlPostVariableListCallback postForm1("configform*", configFormPostCallBack);

I only get the first 255 bytes in pValue (with a null-terminator), regardless of how much text I have in the textarea on the web page. (In my code, strlen(pValue) is never more than 255.)

HTTP_RX_BUFFERSIZE in constants.h is 10000.

I get the same results from Chrome and Edge. Adding the maxlength="2500" to the textarea doesn't make a difference.

Is there some way to receive larger text blocks?

Thanks

jaypdx · Post by **jaypdx** » Wed Dec 23, 2020 8:42 pm

I went into httppost.cpp and increased MAX_VALUE_SIZE to 4096, which is large enough for my application, and now I'm getting all the data in my callback handler. But this is a little scary - is this the right way to do this? did I break something else?

I wonder what the best way is to capture changes to the RTOS source in version control.

Post by **TomNB** » Thu Dec 24, 2020 8:58 am

Hello,

The reason for the smaller size is that we can run on platforms as low as 32k of ram, so the defaults are the most common size.

This is a good example of the override feature in NetBurner 3.x. If you look at your eclipse project you will see a directory called "override". There is a readme in that directory that explains how to use it, but the idea is that if you need to modify a system file you put it in there and leave the original intact. Anything in the override folder will take precedence. In this case:

- The override requires the same folder structure as the system files, so in override, create folders nbrtos\source.
- Copy httppost.cpp to the source folder
- Modify your MAX_VALUE_SIZE variable
- In the eclipse project window, click on Build Targets -> Clean NetBurner System Libraries.
- Do a clean on your project so it rebuilds I use right-click, Clean Project

Now any changes you make to httppost.cpp in the override directory will be incorporated into your project. You only need to do the build target clean procedure when you add new files to the override.

All your other projects will be built with the unmodified system files.

Post by **pbreed** » Thu Dec 24, 2020 9:11 am

What platform and what tools revision?

jaypdx · Post by **jaypdx** » Thu Dec 24, 2020 1:42 pm

I'm using 3.3.0 of the NNDK.

Thanks for info about the overload directory. It seems to work well and will help a lot with version control.

There is one strange thing... when I open httppost.cpp in the overload directory Eclipse flags a some warnings that don't show up when I open the file in it's 'native' location (c:\nburn\nbrtos\source). I attached an image of what I'm seeing - the warnings are "IoExpandStruct could not be resolved", "GetExtraData could not be resolved", etc. I can't do an 'open declaration' on IoExpandStruct, even though iointernal.h is accessible through my Includes (in \nburn\nbrtos\include). It's not a big deal, but it's probably not supposed to work this way.

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Callback getting max 255 bytes of data from TEXTAREA in FORM

Callback getting max 255 bytes of data from TEXTAREA in FORM

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Re: Callback getting max 255 bytes of data from TEXTAREA in FORM