Pastable version of Sanitize HTML

<pre class='prettyprint' language='cs'>private static Regex _tags = new Regex(&quot;&lt;[^&gt;]*(&gt;|$)&quot;,
    RegexOptions.Singleline | RegexOptions.ExplicitCapture | RegexOptions.Compiled);
private static Regex _whitelist = new Regex(@&quot;
    ^&lt;/?(b(lockquote)?|code|d(d|t|l|el)|em|h(1|2|3)|i|kbd|li|ol|p(re)?|s(ub|up|trong|trike)?|ul)&gt;$|
    ^&lt;(b|h)r\s?/?&gt;$&quot;,
    RegexOptions.Singleline | RegexOptions.ExplicitCapture | RegexOptions.Compiled | RegexOptions.IgnorePatternWhitespace);
private static Regex _whitelist_a = new Regex(@&quot;
    ^&lt;a\s
    href=&quot;&quot;(\#\d+|(https?|ftp)://[-a-z0-9+&amp;@#/%?=~_|!:,.;]+)&quot;&quot;
    (\stitle=&quot;&quot;[^&quot;&quot;&lt;&gt;]+&quot;&quot;)?\s?&gt;$|
    ^&lt;/a&gt;$&quot;,
    RegexOptions.Singleline | RegexOptions.ExplicitCapture | RegexOptions.Compiled | RegexOptions.IgnorePatternWhitespace);
private static Regex _whitelist_img = new Regex(@&quot;
    ^&lt;img\s
    src=&quot;&quot;https?://[-a-z0-9+&amp;@#/%?=~_|!:,.;]+&quot;&quot;
    (\swidth=&quot;&quot;\d{1,3}&quot;&quot;)?
    (\sheight=&quot;&quot;\d{1,3}&quot;&quot;)?
    (\salt=&quot;&quot;[^&quot;&quot;&lt;&gt;]*&quot;&quot;)?
    (\stitle=&quot;&quot;[^&quot;&quot;&lt;&gt;]*&quot;&quot;)?
    \s?/?&gt;$&quot;,
    RegexOptions.Singleline | RegexOptions.ExplicitCapture | RegexOptions.Compiled | RegexOptions.IgnorePatternWhitespace);

/// &lt;summary&gt;
/// sanitize any potentially dangerous tags from the provided raw HTML input using 
/// a whitelist based approach, leaving the &quot;safe&quot; HTML tags
/// CODESNIPPET:4100A61A-1711-4366-B0B0-144D1179A937
/// &lt;/summary&gt;
public static string Sanitize(string html)
{
    if (String.IsNullOrEmpty(html)) return html;

string tagname;
    Match tag;

// match every HTML tag in the input
    MatchCollection tags = _tags.Matches(html);
    for (int i = tags.Count - 1; i &gt; -1; i--)
    {
        tag = tags[i];
        tagname = tag.Value.ToLowerInvariant();
        
        if(!(_whitelist.IsMatch(tagname) || _whitelist_a.IsMatch(tagname) || _whitelist_img.IsMatch(tagname)))
        {
            html = html.Remove(tag.Index, tag.Length);
            System.Diagnostics.Debug.WriteLine(&quot;tag sanitized: &quot; + tagname);
        }
    }

return html;
}</pre>
<a href="http://www.refactormycode.com/codes/333-sanitize-html" style="color:#fff" title="As seen on RefactorMyCode.com"><img alt="Small_logo" src="http://www.refactormycode.com/images/small_logo.gif" style="border:0" /></a>

Refactor :my => 'code'

Recent

Popular

Pastable version of Sanitize HTML