Firefox extension to get google pagerank and alexa ranking - firefox

Question

I am creating a Mozilla Firefox toolbar to show PageRank and Alexa ranking of current website. One way I came to know is to use XMLHttpRequest in my JavaScript file to get information from a PHP page hosted on my website's server.
The PHP class has this function:
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
$out = "GET /tbr?client=navclient-auto&ch=".$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 $result;
}
Is there a better way to get page ranks in my custom Firefox toolbar without having to host a PHP service?
// Create a url hash
function createHash($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;
}

Answer 1

If your PHP code only makes an HTTP request then you can just do the same request from the Firefox extension as well:
var request = new XMLHttpHeader();
request.open("http://toolbarqueries.google.com/tbr?client=navclient-auto&ch=...");
request.setRequestHeader("User-Agent", "Mozilla/4.0 (compatible; GoogleToolbar 2.0.114-big; Windows XP 5.1)");
request.send();
However, you should clarify whether this use of a Google server (particularly masquerading as Google Toolbar) complies with their Terms of Service. Otherwise you might find yourself confronted with legal action or at the very least sudden changes in the way this web service works.
As to the hash function: obviously you can either translate this algorithm to JavaScript (which is pretty straightforward from the look of it) or search around to see whether anybody did it already. E.g. I found this JS-based hash algorithm implementation (it's a different algorithm that is prefixed with 8 instead of 7 however, note also that this prefix isn't returned by the hash function but is rather part of the URL there).