Question

I need to find all src and href’s in a string and replace them with a fully quilifies url.

ex:
src=”/test/style.css?somethinghere” becomes src=”http://www.mydomain.com/test/style.css?somethinghere”

and the same goes for href’s.

I will use them in a web relay server.

I will use regex replace, but what does the regex look like?

Answer 1

You are missing important information, like: what type of regular expression you are interested in. I am assuming that you are referring to perl-compatible regular expression.

In any case this will help in the guidance and theory and answer, and if you let me know the engine/language used I can probably help adapt this to your needs.

I use something similar to collect, pre-process, filter and forward relevant news feeds from various places. MSDN has this problem of relative URIs, here is my configuration for this:

'msdn' => {
             'action' => [
                         {
                           'tag' => 'get_url_as_content'
                         },
...
...
                         {
                           'regex' => 's/<img( [^\\/>]*)src="\\//<img$1src="http:\\/\\/blogs.msdn.com\\//gsi',
                           'tag' => 'mod_content'
                         },
                         {
                           'regex' => 's/<a( [^\\/>]*)href="\\//<a$1href="http:\\/\\/blogs.msdn.com\\//gsi',
                           'tag' => 'mod_content'
                         }
...
...
                       ]
           },

Here you can see the two regular expressions that I am using.

This one restores the content between img and src words and then makes the URLs absolute.

s/<img( [^\/>]*)src="\//<img$1src="http:\/\/blogs.msdn.com\//gsi

Similarly for anchor tags…

s/<a( [^\/>]*)href="\//<a$1href="http:\/\/blogs.msdn.com\//gsi

These have been working for quite some time now, over 3 years without issues 🙂

Hope this helps.