Checking URLS before connecting with EZproxy

Much like many other institutions Brock uses EZproxy to connect users to off-campus resources.  In theory everything works perfectly however not always.  I wanted to create a web-app that would form an EZproxy request to a particular website and return yes if the URL was in the ezproxy.cfg file.  My first attempt at this was using a straight PHP based command line approach.  The bad news is that security settings in EZproxy wouldn't allow this to happen, which makes perfect sense looking back at it now.  So I tried to see if EZproxy had built in support for this.  Much to my happiness EZproxy recently implemented an XML based service that does what I need.

Basically you format an XML object and send it to your Ezproxy software.  It returns back an XML object with some great diagnostic information about the request.  In particular if it connected.  Like many great features of EZproxy this is not documented well.  In fact the only real mention of it that I found was on the update page that gets created everytime a new version of the software is out.  Look for something called: ProxyURLPassword.

The Setup

You basically set the line: ProxyURLPassword somepassword in ezproxy.cfg and restart the server.  At that point it is ready to go.

Using PHP's simple XML object, here is the specific chunk of code that creates the request, sends it off and evaluates the results from the EZproxy server:

$site_xml_lu = 'http://ezproxy.edu/proxy_url?xml=%3C?xml%20version=%221.0%22?%3E%3Cproxy_url_request%20password= %22somepassword%22%3E%3Curls%3E%3Curl%3E'.$url_in.'%3C/url%3E%3C/urls%3E%3C/proxy_url_request%3E';

$sxe = new SimpleXMLElement($site_xml_lu, NULL, TRUE);

$string = $sxe->asXML();

if (strstr($string, "url proxy=\"true\""))

   echo "Yah look up worked!";

else

   echo "Look up failed. Please contact the library";

The Explanation

• Here is the what is right after "$site_xml_lu=" after it has been URL decoded: "http://ezproxy.edu/proxy_url?xml=<?xml version="1.0"?><proxy_url_request password="somepassword"><urls><url>$url_in</url></urls></proxy_url_request>"

• "http://ezproxy.edu/proxy_url?"  is the domain name of your proxy instance with /proxy_url? appended
•  somepassword is the same one in your ezproxy.cfg file. and $url_in is the name of the variable I gave the incoming URL you want to look up.
• The substr checks to see if "true" is in the returned XML object, indicating that the lookup worked.

You can try this directly in web-based environment by going directly to http://ezproxy.edu/proxy_url (where of course you use the domain name of your ezproxy install).  Trying it on the web really  makes it clear as to how your XML request needs to look.  In fact it gives you a text box with a built example that you can crib from.

After wrapping it up with some AJAX and some other reporting functions the end result is here:

http://library.brocku.ca/proxy/checker.php