PageRank 改變計算方式

Posted on August 20, 2009 by

最近 PageRank 計算的公式改變，已經無法用舊的 HASH 值取回正確的 PR ，會出現錯誤訊息

一般來講，網路上取回 PR 的程式都是算出一串 URL 後丟給 Google ，然後把解讀回傳值，會像是這樣：

http://www.google.com/search?client=navclient-auto&ch=6-9223293982612316911&features=Rank&q=info:roga.tw

可以拆解成幾個部份來看：


$site = 'http://www.example.com'; /* 你的 url */
$info = 'info:' . urldecode($site);	
$checksum = $this->checksum($this->strord($info));
$url = "http://www.google.com/search?client=navclient-auto&ch=6{$checksum}&features=Rank&q={$info}";

$site = 'http://www.example.com'; /* 你的 url */

$info = 'info:' . urldecode($site);

$checksum = $this->checksum($this->strord($info));

$url = "http://www.google.com/search?client=navclient-auto&ch=6{$checksum}&features=Rank&q={$info}";

接著把 $url 用 curl 或是 fopen 之類的方法取回即可。

裡面最重要的就是計算 checksum 這組 hash value 的方法，舊有的方法如下，我們可以看到幾個地方有 Magic Number ，像是上面 $url 字串中包含的 &ch=6 以及後面接 $checksum，以及下面程式碼中計算 checksum 的 $init = 0xE6359A60


    /**
     * Pagerank checksum hash emulator
     */	
	function checksum ($url, $length = null, $init = 0xE6359A60) 
	{
		if (is_null($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 = $this->mix($a,$b,$c);
			$a = $mix[0]; $b = $mix[1]; $c = $mix[2];
			$k += 12;
			$len -= 12;
		}
		
		$c += $length;
		
		switch($len)
		{
			case 11: $c += ($url[$k + 10] << 24);
			case 10: $c += ($url[$k + 9] << 16);
			case 9: $c += ($url[$k + 8] << 8);
			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]);
		}
		
		$mix = $this->mix($a, $b, $c);
		
		return $mix[2];
		
    }
    /**
     * Converts number to int 32
     * (Required for pagerank hash)
     */
	function to_int_32 (&$x)
	{
		$z = hexdec(80000000);
		$y = (int) $x;
		if($y ==- $z && $x <- $z)
		{
			$y = (int) ((-1) * $x);
			$y = (-1) * $y;
		}
		$x = $y;
	}
    
    /**
     * Fills in zeros on a number
     * (Required for pagerank hash)
     */
	function zero_fill ($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;
	}
    
    /**
     * Pagerank hash prerequisites
     */
	function mix($a, $b, $c) 
	{
		$a -= $b; $a -= $c; $this->to_int_32($a); $a = (int)($a ^ ($this->zero_fill($c,13)));
		$b -= $c; $b -= $a; $this->to_int_32($b); $b = (int)($b ^ ($a<<8));
		$c -= $a; $c -= $b; $this->to_int_32($c); $c = (int)($c ^ ($this->zero_fill($b,13)));
		$a -= $b; $a -= $c; $this->to_int_32($a); $a = (int)($a ^ ($this->zero_fill($c,12)));
		$b -= $c; $b -= $a; $this->to_int_32($b); $b = (int)($b ^ ($a<<16));
  		$c -= $a; $c -= $b; $this->to_int_32($c); $c = (int)($c ^ ($this->zero_fill($b,5)));
		$a -= $b; $a -= $c; $this->to_int_32($a); $a = (int)($a ^ ($this->zero_fill($c,3)));
		$b -= $c; $b -= $a; $this->to_int_32($b); $b = (int)($b ^ ($a<<10));
		$c -= $a; $c -= $b; $this->to_int_32($c); $c = (int)($c ^ ($this->zero_fill($b,15)));
		return array($a,$b,$c);
	}    
    /**
     * ASCII conversion of a string
     */    
    function strord($string)
    {
    	for($i = 0; $i < strlen($string); $i++)
    	{
    		$result[$i] = ord($string{$i});
    	}    	
    	return $result;
    }
    
    /**
     * Number formatting for use with pagerank hash
     */
    function format_number ($number='', $divchar = ',', $divat = 3)
    {
    	$decimals = '';
    	$formatted = '';
    	
    	if (strstr($number, '.'))
    	{
    		$pieces = explode('.', $number);
    		$number = $pieces[0];
    		$decimals = '.' . $pieces[1];
    	}
    	else
    	{
    		$number = (string) $number;
    	}
    	
    	if (strlen($number) <= $divat)
    		return $number;
    	
    	$j = 0;
    	
    	for ($i = strlen($number) - 1; $i >= 0; $i--) 
    	{
    		if ($j == $divat)
    		{
    			$formatted = $divchar . $formatted;
    			$j = 0;
    		}    		    	
    		$formatted = $number[$i] . $formatted;
    		$j++;    		
    	}    	
    	return $formatted . $decimals;    	
    }

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/**

* Pagerank checksum hash emulator

function checksum ($url, $length = null, $init = 0xE6359A60)

{

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 = $this->mix($a,$b,$c);

$a = $mix[0]; $b = $mix[1]; $c = $mix[2];

$k += 12;

$len -= 12;

}

$c += $length;

switch($len)

{

case 11: $c += ($url[$k + 10] << 24);

case 10: $c += ($url[$k + 9] << 16);

case 9: $c += ($url[$k + 8] << 8);

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]);

}

$mix = $this->mix($a, $b, $c);

return $mix[2];

}

/**

* Converts number to int 32

* (Required for pagerank hash)

function to_int_32 (&$x)

{

$z = hexdec(80000000);

$y = (int) $x;

if($y ==- $z && $x <- $z)

{

$y = (int) ((-1) * $x);

$y = (-1) * $y;

}

$x = $y;

}

/**

* Fills in zeros on a number

* (Required for pagerank hash)

function zero_fill ($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;

}

/**

* Pagerank hash prerequisites

function mix($a, $b, $c)

{

$a -= $b; $a -= $c; $this->to_int_32($a); $a = (int)($a ^ ($this->zero_fill($c,13)));

$b -= $c; $b -= $a; $this->to_int_32($b); $b = (int)($b ^ ($a<<8));

$c -= $a; $c -= $b; $this->to_int_32($c); $c = (int)($c ^ ($this->zero_fill($b,13)));

$a -= $b; $a -= $c; $this->to_int_32($a); $a = (int)($a ^ ($this->zero_fill($c,12)));

$b -= $c; $b -= $a; $this->to_int_32($b); $b = (int)($b ^ ($a<<16));

$c -= $a; $c -= $b; $this->to_int_32($c); $c = (int)($c ^ ($this->zero_fill($b,5)));

$a -= $b; $a -= $c; $this->to_int_32($a); $a = (int)($a ^ ($this->zero_fill($c,3)));

$b -= $c; $b -= $a; $this->to_int_32($b); $b = (int)($b ^ ($a<<10));

$c -= $a; $c -= $b; $this->to_int_32($c); $c = (int)($c ^ ($this->zero_fill($b,15)));

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

}

/**

* ASCII conversion of a string

function strord($string)

{

for($i = 0; $i < strlen($string); $i++)

{

$result[$i] = ord($string{$i});

}

return $result;

}

/**

* Number formatting for use with pagerank hash

function format_number ($number='', $divchar = ',', $divat = 3)

{

$decimals = '';

$formatted = '';

if (strstr($number, '.'))

{

$pieces = explode('.', $number);

$number = $pieces[0];

$decimals = '.' . $pieces[1];

}

else

{

$number = (string) $number;

}

if (strlen($number) <= $divat)

return $number;

$j = 0;

for ($i = strlen($number) - 1; $i >= 0; $i--)

{

if ($j == $divat)

{

$formatted = $divchar . $formatted;

$j = 0;

}

$formatted = $number[$i] . $formatted;

$j++;

}

return $formatted . $decimals;

}

我後來在 http://wpcn.googlecode.com 找到一個新的 Google PageRank checksum 算法，它是針對 WP 寫的，稍微改寫一下就可以使用了。


$info = urlencode("info:".$site);
$checksum = $this->CheckHash($this->HashURL($site));
$url = "http://www.google.com/search?client=navclient-auto&ch=$checksum&features=Rank&=$info"

$info = urlencode("info:".$site);

$checksum = $this->CheckHash($this->HashURL($site));

$url = "http://www.google.com/search?client=navclient-auto&ch=$checksum&features=Rank&=$info"

最重要的 $checksum 計算方法如下：



	//convert a string to a 32-bit integer
	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;
	}

	//genearate a hash for a url
	function HashURL($String) {
		$Check1 = $this->StrToNum($String, 0x1505, 0x21);
		$Check2 = $this->StrToNum($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);
	}
	
	//genearate a checksum for the hash string
	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;
	}

//convert a string to a 32-bit integer

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;

}

//genearate a hash for a url

function HashURL($String) {

$Check1 = $this->StrToNum($String, 0x1505, 0x21);

$Check2 = $this->StrToNum($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);

}

//genearate a checksum for the hash string

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;

}

裡面一樣有 Magic Number ，像是 CheckHash() 的 return value。接著一樣把 $url 用 curl 或是 fopen 之類的方法取回即可。

唉，我還是不懂為什麼 Google 不提供取回 PR 的 API 。

Posted in Programming

6 comments on “PageRank 改變計算方式”

野貓 says:

August 20, 2009 at 14:05

對啊，直接提供一個讓大家丟網址過去他就吐數字回來的小工具不好嗎 Q_Q

Reply
help me says:

August 28, 2009 at 20:55

roga大大,很抱歉在這邊打擾你,我是sitestates的使用者,因為在那邊po留言板一直失敗,所以在這邊向你求助

我前天開始登入一直失敗,在我輸入完帳號密碼按了送出,結果畫面就像甚麼都沒發生一樣,帳號密碼欄還是空白等著我輸入的狀態

我有試著去申請忘記密碼,用系統給的新帳號登入,可是情況也是一樣><

ps,請問有辦法刪除以前自己留言版的留言嗎?一點小小的隱私問題@@

Reply
- roga says:
  
  August 28, 2009 at 23:01
  
  您好，請試著清除瀏覽器的 Cookie 再試一次，謝謝您 🙂
  
  Reply
help me says:

August 31, 2009 at 23:31

roga大大,
我發現是瀏覽器的問題,因為我下載了GreenBrowser就沒問題了
如果以後有人跟我一樣是vista ie打不開的,
清cookie也沒用的話
可以叫他們下載這個瀏覽器試試看喔

謝謝你^^

Reply
- roga says:
  
  September 1, 2009 at 17:06
  
  非常抱歉呢！～謝謝你唷 ^^
  
  Reply
CL says:

October 6, 2009 at 00:30

roga大大,
我發現是瀏覽器的問題,因為我下載了GreenBrowser就沒問題了
如果以後有人跟我一樣是vista ie打不開的,
清cookie也沒用的話
可以叫他們下載這個瀏覽器試試看喔
謝謝你^^

Reply