safe html filtering with php?

Question

function validCleanHtml( $unclosedString )
{
    preg_match_all( "/<([^\/]\w*)>/", $closedString = $unclosedString, $tags );
    for ( $i = count( $tags[1] ) - 1; $i >= 0; $i-- )
    {
        $tag = $tags[1][$i];
        if ( substr_count( $closedString, "</$tag>" ) < substr_count( $closedString, "<$tag>" ) )
            $closedString .= "</$tag>";
    }
    $validTags = "<em><strong>";
    $validClosedString = strip_tags( $closedString, $validTags );
    return $validClosedString;

}

ok what i want is to enable 2 html, em and strong, is this just secure from xss ? if not how can we secure it ?

jasonbar · Accepted Answer · 2010-07-29 17:40:25Z

12

Have you looked at any existing solutions like htmlpurifier? You really don't want to write your own HTML parser - and certainly not with regular expressions.

answered Jul 29, 2010 at 17:40

jasonbar

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1 Comment

FernandoZ Over a year ago

I think something like this is the way to go for safehtml. I don't think it is necessary to re-invent the wheel. This is exactly what I was looking for, even though it may not be exactly what the original poster of this question was looking for.

Community · Accepted Answer · 2023-11-17 20:38:18Z

4

I think that strip_tags holds the answer.

https://www.php.net/strip_tags

Rather than enabling certain fields, you could also remove the ones you don't want. Namely: link, style, script, iframe, frame

edited Nov 17, 2023 at 20:38

CommunityBot

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answered Jul 29, 2010 at 17:39

Mitch Dempsey

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1 Comment

Charles Over a year ago

@Adam, please consider @jasonbar's answer as well. It provides superior filtering options than strip_tags.

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