form getting spammed...how to block it out

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Hello folks.

I've been having issues lately with a bot spamming my form with BB code. as such..

[url=http://www.example.com/]viagra on line[/url]

I tried this function..

function vKill($title) {
	if (preg_match("/[url=http/", $title)) {
		return TRUE;
	} else {
		return FALSE;
		}
}

to no avail..
anyone have any suggestions?

I just need to check for certain patterns and if they exist block the form from being sent.

Thanks much!

etully

The [ character (square bracket) has a special meaning inside a regular expression. Remove that for starters or escape it by putting a backslash in front of it.

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I removed the bracket.. but its still not working.
I even tried with a simple =.
Is that also a special character in a regular expression?

Bobulous

Try this:

preg_match("/\[url=http/i", $title);

The [ should escape the left-square-bracket safely. The i modifier (which comes after the end-of-pattern forward-slash) tells the matcher to be case-insensitive.

If this doesn't return true on a $title string that you are sure it should, then examine the $title string to make sure there are no tricks being used to break up the url=http part. I don't see how Javascript could be used to break it up and still cause the BB code to work, but it's worth checking out.

If URLs are causing you this much trouble, doesn't the BB software allow you to disable them?

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Thanks for the update.
I ended going sort of the backward approach, which seems more robust anyway.

Since it's supposed to be accepting a phrase or question. I'm only allowing alpha numeric characters and some punctuation.

Thanks much for the reply. I wil certainly try it out.

function vKill($short) {
	$exp = "[^a-z0-9.,?!' ]";
	if (eregi("$exp", "$short")) 
	{
		return FALSE;
	}
	else
	{
		return TRUE;
	}
}