Question

I have a dynamically generated list of URL’s from our internal network. For each URL, I want to:

1. Find the IP of the URL.
2. Compare the IP to a list of IP’s and their associated server.
3. Return the server associated with the IP.

The IP of course is UNIQUE in the list of IP’s, so is there a recommended way to initially store the list of IP values so I can supply it with a an IP (key) and get back the associated server (value)?

I’ve looked at multidimensional arrays, or even brute force — just create an array for each individual server’s IP list — but that seems inefficient.

Here is the PHP I want to have (psuedo):

$IPServerList = array(0 => array(ip=>1.2.3.4,server=>"server1"),
       1 => array(ip=>2.1.3.4,server=>"server2"),
       2 => array(ip=>3.1.3.3,server=>"server1"));

getServer("url1.mycoolurl.com");

function getServer($url) {
    $ip = gethostbyname($url);
"Search $IPServerList for this $ip and return the 'server' value"
    // 

}

Are there any specific ways I should be storing the IP/Server list? Any recommended built in PHP functions to do the search? Any help is appreciated!

Answer 1

I’m not seeing any obvious reason for avoiding associative arrays:

$IPServerList = array(
  '1.2.3.4' => "server1",
  '2.1.3.4' => "server2",
  '3.1.3.3' => "server1",
);

Arrays in PHP double has hashs/maps/dictionaries, depending on what you’re used to calling them. The point is, you can use any unique string/number for your array index, and since you seem to have a 1-to-1 mapping of IPs to server names, this seems ideal.

I don’t think you’re likely going to find a faster way in PHP to access your data, and you can’t beat it for simplicity:

 if (array_key_exists($IPServerList, '192.168.1.1')) {
   echo $IPServerList['192.168.1.1'];
 }

The PHP manual on arrays will be useful.