hey-red / Markdown

Open source C# implementation of Markdown processor, as featured on Stack Overflow.

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Option to render URLs with rel="nofollow"

GoogleCodeExporter opened this issue · comments

The site I'm developing will suffer from questionable behaviour by people with 
commercial interests if we let them post URLs without rel="nofollow" on all 
HTML anchors generated in Markdown.

I've attached a patch (generated by Git) of the changes I made to Markdown.cs 
in implementing support for this.

I haven't changed the default behaviour.  Just set the NoFollowLinks property 
to true if you want to opt into this behaviour.

Version number bumped too.

Original issue reported on code.google.com by drewnoakes on 6 Oct 2010 at 11:27

Attachments:

we generally want to decide to nofollow based on a heuristic, e.g., is this 
link inside our network at http://stackexchange.com/sites -- or outside it?

In my opinion, nofollowing links should be done as a separate pass. I guess I 
could support "nofollow everything by default, then unfollow just the safe 
links" but either way it is a loop across all the URLs in the input with some 
custom logic that isn't really markdown specific.

Original comment by wump...@gmail.com on 12 Nov 2010 at 8:52

Original comment by wump...@gmail.com on 12 Nov 2010 at 9:02

  • Added labels: Priority-Low
  • Removed labels: Priority-Medium

Original comment by wump...@gmail.com on 12 Nov 2010 at 9:03

  • Added labels: Type-Enhancement
  • Removed labels: Type-Defect
Good point about deciding whether to include the attribute based on some 
property of the link.  In fact I think that's something I would like to do for 
my app too, now you mention it.

However I'd still like to do this in a single pass, just to reduce the amount 
of string churning on the server.  I think it'd be simpler to code too.  I'll 
hook up a callback mechanism that passes out the URL to some optional external 
code in order to decide whether to mark the link as nofollow or not.

Let me know if you're interested in a patch or not.

Original comment by drewnoakes on 18 Nov 2010 at 2:53