Google PageRank PHP Class

While developers and designers can debate about the important of different search engine optimizations strategies, one metric that simply can't be argued is a website's Google PageRank, or its importance in driving traffic to the site.  Achieving a better PageRank was a consideration when redesigning this blog.  We can discuss how to achieve a better PageRank in another post -- this post will focus on how you can retrieve a page's Google PageRank using a small PHP class that I have created.

The PHP

The base functions within this class were created by Jamie Scott -- all credit for the base functions go to him.  I've simply placed the functionality into PHP class format for easy use and updated the code to be a bit more transparent.  As far as PHP classes go, this one is quite small:

// Declare the class
class GooglePageRankChecker {
	
	// Track the instance
	private static $instance;
	
	// Constructor
	function getRank($page) {
		// Create the instance, if one isn't created yet
		if(!isset(self::$instance)) {
			self::$instance = new self();
		}
		// Return the result
		return self::$instance->check($page);
	}
	
	
	// Convert string to a number
	function stringToNumber($string,$check,$magic) {
		$int32 = 4294967296;  // 2^32
	    $length = strlen($string);
	    for ($i = 0; $i < $length; $i++) {
	        $check *= $magic; 	
	        //If the float is beyond the boundaries of integer (usually +/- 2.15e+9 = 2^31), 
	        //  the result of converting to integer is undefined
	        //  refer to http://www.php.net/manual/en/language.types.integer.php
	        if($check >= $int32) {
	            $check = ($check - $int32 * (int) ($check / $int32));
	            //if the check less than -2^31
	            $check = ($check < -($int32 / 2)) ? ($check + $int32) : $check;
	        }
	        $check += ord($string{$i}); 
	    }
	    return $check;
	}
	
	// Create a url hash
	function createHash($string) {
		$check1 = $this->stringToNumber($string, 0x1505, 0x21);
	    $check2 = $this->stringToNumber($string, 0, 0x1003F);
	
		$factor = 4;
		$halfFactor = $factor/2;

	    $check1 >>= $halfFactor;
	    $check1 = (($check1 >> $factor) & 0x3FFFFC0 ) | ($check1 & 0x3F);
	    $check1 = (($check1 >> $factor) & 0x3FFC00 ) | ($check1 & 0x3FF);
	    $check1 = (($check1 >> $factor) & 0x3C000 ) | ($check1 & 0x3FFF);	

	    $calc1 = (((($check1 & 0x3C0) << $factor) | ($check1 & 0x3C)) << $halfFactor ) | ($check2 & 0xF0F );
	    $calc2 = (((($check1 & 0xFFFFC000) << $factor) | ($check1 & 0x3C00)) << 0xA) | ($check2 & 0xF0F0000 );

	    return ($calc1 | $calc2);
	}
	
	// Create checksum for hash
	function checkHash($hashNumber)
	{
	    $check = 0;
		$flag = 0;

		$hashString = sprintf('%u', $hashNumber) ;
		$length = strlen($hashString);

		for ($i = $length - 1;  $i >= 0;  $i --) {
			$r = $hashString{$i};
			if(1 === ($flag % 2)) {			  
				$r += $r;	 
				$r = (int)($r / 10) + ($r % 10);
			}
			$check += $r;
			$flag ++;	
		}

		$check %= 10;
		if(0 !== $check) {
			$check = 10 - $check;
			if(1 === ($flag % 2) ) {
				if(1 === ($check % 2)) {
					$check += 9;
				}
				$check >>= 1;
			}
		}

		return '7'.$check.$hashString;
	}
	
	function check($page) {

		// Open a socket to the toolbarqueries address, used by Google Toolbar
		$socket = fsockopen("toolbarqueries.google.com", 80, $errno, $errstr, 30);

		// If a connection can be established
		if($socket) {
			// Prep socket headers
			$out = "GET /search?client=navclient-auto&ch=".$this->checkHash($this->createHash($page))."&features=Rank&q=info:".$page."&num=100&filter=0 HTTP/1.1\r\n";
			$out .= "Host: toolbarqueries.google.com\r\n";
			$out .= "User-Agent: Mozilla/4.0 (compatible; GoogleToolbar 2.0.114-big; Windows XP 5.1)\r\n";
			$out .= "Connection: Close\r\n\r\n";

			// Write settings to the socket
			fwrite($socket, $out);

			// When a response is received...
			$result = "";
			while(!feof($socket)) {
				$data = fgets($socket, 128);
				$pos = strpos($data, "Rank_");
				if($pos !== false){
					$pagerank = substr($data, $pos + 9);
					$result += $pagerank;
				}
			}
			// Close the connection
			fclose($socket);
			
			// Return the rank!
			return $result;
		}
	}
}

The createHash and checkHash methods perform the deep down mathematical operations.  Once those are out of the way, the check method connects to Google's toolbar server, disguising itself as a toolbar via the User-Agent header, to get the page's PageRank.  A singleton pattern is used since creating individual instances isn't important:

$rank = GooglePageRankChecker::getRank("davidwalsh.name"); // returns "5"

The number provided back represents the PageRank for the URL provided!  This PHP class can be used on its own, but I've created a MooTools-powered script to retrieve an address' PageRank via some simple AJAX.

The MooTools JavaScript

This MooTools quick inline MooTools script responds to a button click, making an AJAX call to a PHP script that runs the class provided above:

// When the DOM is ready
window.addEvent("domready",function() {
	
	// When the form is submitted...
	var form = document.id("rankForm"), request, display, domain;
	form.addEvent("submit",function(e) {
		// Stop the event
		if(e) e.stop();
		
		// Create request, if not already created
		if(!request) {
			domain = document.id("domain");
			display = document.id("rankerDisplay");
			request = new Request({
				url: "pagerank-checker.php", 
				method: "post",
				onComplete: function(response) {
					display.setStyle("display","block").set("text","Page rank for " + domainValue + " is: " + response);
				}
			});
		}
		
		// Get the value fo the URL
		domainValue = domain.get("value");
		
		// Send the request
		request.send({ data: { domain: domainValue } });
	});
	
});

Using a JavaScript snippet like this, you could easily add a JavaScript-fronted Google PageRank checker with the framework of your choosing.

Outstanding work by Jamie Scott in creating the base functions to retrieve a page's Google PageRank with PHP.  Hopefully my class makes the PageRank code a bit more portable and recognizable.