Mashed integer causes fundamental logic change in httpbl_check()

Though the solution to this one is easy, this took a long time and a lot of testing with debug logging to find.

If I correctly understand the overall intended logic of httpbl_check(), it goes like this:

#1 - If we've already calculated a result for our user, we're done (return). Otherwise...
#2 - We check to see if the user is already white-listed, else
#3 - If we're caching results, we look for the user in our cache table.
#4 - We check the results of #3, and if it's not an integer (0,1 or 2), we proceed with a DNS lookup and checking to see if the user is malicious and should be grey or blacklisted, or if they're safe, etc.

My testing found that #4 was always happening because the test of #3 results was not an integer, even when it appeared to be a 0, 1 or 2.

I tested this by asking a friend (whose IP I know) to visit a web site with httpbl installed. Before they visited I manually added them to the cache table as a greylisted user (2). However, what happened when they arrived at the site was nothing but the usual experience. They were not greylisted. When I checked the httpbl cache table after their visit, their status was 0, Safe or white-listed in cache only (not the {access} table).

Later I kept repeating this test by manually grey-listing my own IP and visiting the site with a second browser. I kept not getting blacklisted, but getting cache whitelisted. Eventually I added debug logging to each step along the way, to see what was happening.

It turned out that even though I was found in the cache table with a status of 2, a DNS lookup was happening anyway, and because my IP address is not really evil, I was being deemed safe and my status changed to a 0.

So the focus became checking out that integer check ... if (!is_int($result)) {. I did some googling and some reading, like...

http://us2.php.net/is_int, http://us2.php.net/manual/en/function.is-numeric.php, http://drupal.org/node/136473 and http://drupal.org/node/27781

So the first thing I tried was changing the line to if (!is_numeric($result)) {. That worked. After that, if I manually greylisted an IP in the cache {httpbl} table, it stayed greylisted until either I changed it back or proceeded with a successful whitelist challenge, or failed and became blacklisted.

I still don't understand what is happening to the $result variable after _httpbl_cache_get() returns the status value in the cache table, but it seems that's where it loses it's integer type.

However, the final solution I used was to change the test back to if (!is_int($result)) {, but make sure $result is forced back to being an integer when it retrieves the cache table status.

(I'll post the patch when I get the number for this issue).