title: Ruby: Detecting broken links without actually crawling the URL?
body: <p>Is there a Ruby gem, or Ruby-esque way to check a webpage for broken links without crawling the actual links and checking for 404's, etc. Basically, I want a solution that works offline, and I want to detect links that are obviously syntactically broken, not links that point to web pages that don't exist.</p>
  
  <p>So for instance, if a link points to "http//stackoverflow.com", that's a syntactically broken link, and I want to detect that. However if a link points to "<a href="http://www.webpagedoesnotexistyet.com" rel="nofollow">http://www.webpagedoesnotexistyet.com</a>" and it returns a 404, I'm OK with not detecting that.</p>