CODEWITHSUNDEEP
asp.net-mvchtml-encode
Zachary Scott
Zachary Scott

Reputation: 21188

ASP.NET MVC: How to allow some HTML mark-up in Html Encoded content?

Is there some magic existing code in MVC 2 to Html.Encode() strings and allow certain html markup, like paragraph marks and breaks? (coming from a Linq to SQL database field)

A horrible code example to achieve the effect:

Html.Encode(Model.fieldName).Replace("&lt;br /&gt;", "<br />")

What would be really nice is to overload something and pass to it an array (or object) full of allowed html tags.

Upvotes: 3

Views: 2570

Answers (3)

Joe Finsterwald
Joe Finsterwald

Reputation: 51

It's not a good idea to create your own whitelist based on regular expressions because you'll likely inadvertently open a security hole for XSS.

From Sanderson's book "Pro ASP.NET MVC3 Framework": "...The only viable mitigation is strict, whitelist-based filtering: use a library like the HTML Agility Pack to ensure the user-supplied markup contains only the tags that you explicitly allow."

Sanderson goes on to supply a link to a site that demonstrates a broad range of XSS techniques that you'd have to test for if you use the regex approach. Check out http://ha.ckers.org/xss.html

Upvotes: 5

Dean Harding
Dean Harding

Reputation: 72678

There is nothing built in to ASP.NET or MVC for this, but it's not that hard to write your own whitelist-based one with regular expressions and so on. Here's one that Jeff wrote, though it's pretty rough around the edges...

Upvotes: 4

griegs
griegs

Reputation: 22770

I can't think of anything off the bat but I guess you could write an extension method that allows you to add a paremeter/list of items to allow.

Html.Encode(Mode.fieldName, List<items> Myitems);

It could modify the allowable tags into &lt; etc and then encodes the rest like normal.

Upvotes: 2

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