Peppy Heppy

URLS to LINKS

written by Paul on September 3rd, 2005 @ 03:07 PM

In acontent management system I was working on at work we noticed there was a couple of problems with how the URLs entered by users broke our web site due to their length. We also had a request to automatically turn hand typed URLs into links, so here is what I did in C#

Added the RegEx namespace:


using System.Text.RegularExpressions;

Here is the method I added to our utility class:


public string URLsToHyperlinks(string sInput)<br />
 {<br />
  return Regex.Replace(sInput, @&quot;(\bhttp://[^ ]+\b)&quot;, @&quot;&lt;a href=&quot;&quot;$0&quot;&quot;&gt;$0&lt;/a&gt;&quot;);<br />
 }

Here is a function that does the same thing only in PHP


function urls_to_hyperlinks($text)<br />
 {<br />
  return preg_replace( &quot;`((http)+(s)?:(//)|(www\.))((\w|\.|\-|_)+)(/)?(\S+)?`i&quot;, &quot;&lt;a href=\&quot;http\\3://\\5\\6\\8\\9\&quot; title=\&quot;\\0\&quot; target=\&quot;_blank\&quot;&gt;\\5\\6&lt;/a&gt;&quot;, $text); <br />
 }

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C# Quickly remove un supported HTML tags from forms

written by Paul on August 29th, 2005 @ 01:14 PM

While building a some forms for a web site, I realized that there were some users that were using HTML tags in forms that I wasn't happy about. I didn't mind some tags since they were hrmless and gives the users who know HTML some ability to alter presentation. So here is what I did in C# to clean up/remove HTM tags. I am sure there are many ways to improve it (so feel free to.)


// this method will remove *most* malicious code leaving allowed 
// HTML intact
public static string stripHTMLTags(string input)
{
    string output = "";
    // break the comments so someone cannot add an open comment
    input = input.Replace("<!--", "");

    // strip out comments and doctype
    Regex docType = new Regex("<!DOCTYPE[.]*>");
    output = docType.Replace(input, "");

    // add target="_blank" to hrefs and remove parts that are 
    // not supported
    output = Regex.Replace(output, "(.*)", @"$5");

    // strip out most known tags except (a|b|br|blockquote|em|h1|h2|
h3|h4|h5|h6|hr|i|li|ol|p|u|ul|strong|sub|sup)
    Regex badTags = new Regex("< [/]{0,1}(abbr|acronym|address|applet
|area|base|basefont|bdo|big|body|button|caption|center|cite|code|col
|colgroup|dd|del|dir|div|dfn|dl|dt|embed|fieldset|font|form|frame
|frameset|head|html|iframe|img|input|ins|isindex|kbd|label|legend
|link|map|menu|meta|noframes|noscript|object|optgroup|option
|param|pre|q|s|samp|script|select|small|span|strike|style|table
|tbody|td|textarea|tfoot|th|thead|title|tr|tt|var|xmp){1}[.]*>");
    return badTags.Replace(output, "");
}

Here were a couple of web sites that I used as a reference: Regular Expression Reference - http://www.regular-expressions.info/reference.html
A somewhat comprehensive list of HTML tags - http://www.w3schools.com/tags/default.asp

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