PHP implementation code of Google PR value

//PageRank Lookup v1.1 by HM2K (update: 31/01/07)
//based on an alogoritham found here: http://pagerank.gamesaga.net/

//settings - host and user agent
$googlehost='toolbarqueries.google.com';
$googleua='Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.0.6) Gecko/20060728 Firefox/1.5';

//字符串转换到32位整数
function StrToNum($Str, $Check, $Magic) {
    $Int32Unit = 4294967296;  // 2^32

    $length = strlen($Str);
    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 >= $Int32Unit) {
            $Check = ($Check - $Int32Unit * (int) ($Check / $Int32Unit));
            //if the check less than -2^31
            $Check = ($Check < -2147483648) ? ($Check + $Int32Unit) : $Check;
        }
        $Check += ord($Str{$i});
    }
    return $Check;
}

//将URL进行哈希编码
function HashURL($String) {
    $Check1 = StrToNum($String, 0x1505, 0x21);
    $Check2 = StrToNum($String, 0, 0x1003F);

    $Check1 >>= 2;
    $Check1 = (($Check1 >> 4) & 0x3FFFFC0 ) | ($Check1 & 0x3F);
    $Check1 = (($Check1 >> 4) & 0x3FFC00 ) | ($Check1 & 0x3FF);
    $Check1 = (($Check1 >> 4) & 0x3C000 ) | ($Check1 & 0x3FFF);

    $T1 = (((($Check1 & 0x3C0) << 4) | ($Check1 & 0x3C)) <<2 ) | ($Check2 & 0xF0F );
    $T2 = (((($Check1 & 0xFFFFC000) << 4) | ($Check1 & 0x3C00)) << 0xA) | ($Check2 & 0xF0F0000 );

    return ($T1 | $T2);
}

//为哈希字符串生成校验码
function CheckHash($Hashnum) {
    $CheckByte = 0;
    $Flag = 0;

    $HashStr = sprintf('%u', $Hashnum) ;
    $length = strlen($HashStr);

    for ($i = $length - 1;  $i >= 0;  $i --) {
        $Re = $HashStr{$i};
        if (1 === ($Flag % 2)) {
            $Re += $Re;
            $Re = (int)($Re / 10) + ($Re % 10);
        }
        $CheckByte += $Re;
        $Flag ++;
    }

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

    return '7'.$CheckByte.$HashStr;
}

//返回pagerank哈希校验码
function getch($url) { return CheckHash(HashURL($url)); }

//返回PR值
function getpr($url) {
    global $googlehost,$googleua;
    $ch = getch($url);
    $fp = fsockopen($googlehost, 80, $errno, $errstr, 30);
    if ($fp) {
       $out = "GET /search?client=navclient-auto&ch=$ch&features=Rank&q=info:$url HTTP/1.1rn";
       //echo "$outn"; //debug only
       $out .= "User-Agent: $googleuarn";
       $out .= "Host: $googlehostrn";
       $out .= "Connection: Closernrn";

       fwrite($fp, $out);

       //$pagerank = substr(fgets($fp, 128), 4); //debug only
       //echo $pagerank; //debug only
       while (!feof($fp)) {
            $data = fgets($fp, 128);
            //echo $data;
            $pos = strpos($data, "Rank_");
            if($pos === false){} else{
                $pr=substr($data, $pos + 9);
                $pr=trim($pr);
                $pr=str_replace("n",'',$pr);
                return $pr;
            }
       }
       //else { echo "$errstr ($errno)n"; } //debug only
       fclose($fp);
    }
}

//生成pagerank图形
function pagerank($url,$width=40,$method='style') {
    if (!preg_match('/^(http://)?([^/]+)/i', $url)) { $url='http://'.$url; }
    $pr=getpr($url);
    $pagerank="PageRank: $pr/10";

    //The (old) image method
    if ($method == 'image') {
    $prpos=$width*$pr/10;
    $prneg=$width-$prpos;
    $html='';
    }
    //The pre-styled method
    if ($method == 'style') {
    $prpercent=100*$pr/10;
    $html='';
    }

    $out=''.$html.'';
    return $out;
}

if ((!isset($_POST['url'])) && (!isset($_GET['url']))) { echo ''; }
if (isset($_REQUEST['url'])) { echo pagerank($_REQUEST['url']); }
?>