Google PageRank的计算源代码

以下转自：http://www.ugia.cn/
最近对google的PageRank比较感兴趣，一直想知道如何不用google toolbar来获取pr值。用嗅探工具获得google toolbar发出请求的url为:http://toolbarqueries.google.com//search?client=navclient-auto&ch=64170410360&ie=UTF-8&oe=UTF-8&features=Rank:FVN&q=info:http%3A//www.ugia.cn,其中的关键部分为ch=64170410360,即CheckSum,不知道这个是用的什么算法得出来的。

苦苦搜索之后,找到如下代码:

转自: http://meese.ath.cx/google via 思路(http://silu.spirezone.com)

源代码如下:

<?php
/**
This code is released unto the public domain
*/
//header("Content-Type: text/plain; charset=utf-8");
define(‘GOOGLE_MAGIC’, 0xE6359A60);

//unsigned shift right
function zeroFill($a, $b)
{
$z = hexdec(80000000);
if ($z & $a)
{
$a = ($a>>1);
$a &= (~$z);
$a |= 0x40000000;
$a = ($a>>($b-1));
}
else
{
$a = ($a>>$b);
}
return $a;
}

function mix($a,$b,$c) {
$a -= $b; $a -= $c; $a ^= (zeroFill($c,13));
$b -= $c; $b -= $a; $b ^= ($a< <8);
$c -= $a; $c -= $b; $c ^= (zeroFill($b,13));
$a -= $b; $a -= $c; $a ^= (zeroFill($c,12));
$b -= $c; $b -= $a; $b ^= ($a<<16);
$c -= $a; $c -= $b; $c ^= (zeroFill($b,5));
$a -= $b; $a -= $c; $a ^= (zeroFill($c,3));
$b -= $c; $b -= $a; $b ^= ($a<<10);
$c -= $a; $c -= $b; $c ^= (zeroFill($b,15));

return array($a,$b,$c);
}

function GoogleCH($url, $length=null, $init=GOOGLE_MAGIC) {
if(is_null($length)) {
$length = sizeof($url);
}
$a = $b = 0x9E3779B9;
$c = $init;
$k = 0;
$len = $length;
while($len >= 12) {
$a += ($url[$k+0] +($url[$k+1]< <8) +($url[$k+2]<<16) +($url[$k+3]<<24));
$b += ($url[$k+4] +($url[$k+5]<<8) +($url[$k+6]<<16) +($url[$k+7]<<24));
$c += ($url[$k+8] +($url[$k+9]<<8) +($url[$k+10]<<16)+($url[$k+11]<<24));
$mix = mix($a,$b,$c);
$a = $mix[0]; $b = $mix[1]; $c = $mix[2];
$k += 12;
$len -= 12;
}

$c += $length;
switch($len) /* all the case statements fall through */
{
case 11: $c+=($url[$k+10]<<24);
case 10: $c+=($url[$k+9]<<16);
case 9 : $c+=($url[$k+8]<<8);
/* the first byte of c is reserved for the length */
case 8 : $b+=($url[$k+7]<<24);
case 7 : $b+=($url[$k+6]<<16);
case 6 : $b+=($url[$k+5]<<8);
case 5 : $b+=($url[$k+4]);
case 4 : $a+=($url[$k+3]<<24);
case 3 : $a+=($url[$k+2]<<16);
case 2 : $a+=($url[$k+1]<<8);
case 1 : $a+=($url[$k+0]);
/* case 0: nothing left to add */
}
$mix = mix($a,$b,$c);
/*——————————————– report the result */
return $mix[2];
}

//converts a string into an array of integers containing the numeric value of the char
function strord($string) {
for($i=0;$i<strlen($string);$i++) {
$result[$i] = ord($string{$i});
}
return $result;
}
// http://www.example.com/ – Checksum: 6540747202
$url = ‘info:’.$_GET[‘url’];
$ch = GoogleCH(strord($url));
$url=’info:’.urlencode($_GET[‘url’]);
echo file_get_contents("http://www.google.com/search?client=navclient-auto&ch=6$ch&ie=UTF-8&oe=UTF-8&features=Rank&q=$url");
/* use curl send the user angent
$curl = curl_init("http://www.google.com/search?client=navclient-auto&ch=6$ch&ie=UTF-8&oe=UTF-8&features=Rank&q=$url");
curl_setopt ($curl, CURLOPT_USERAGENT, "Mozilla/4.0 (compatible; GoogleToolbar 2.0.110-big; Windows 2000 5.0)");
curl_exec($curl);
*/
?>
</></>