解析获取优酷视频真实下载地址的PHP源代码

<?php
//--调用方法/demo.php?url=http://v.youku.com/v_show/id_xmzkyoda2ntey.html
echo getyoukuflv($_get['url']);

function getyoukuflv($url){
    preg_match("#id_(.*?)\.html#",$url,$out);
    $id=$out[1];
    $content=get_curl_contents('http://v.youku.com/player/getplaylist/videoids/'.$id);
    $data=json_decode($content);
    foreach($data->data[0]->streamfileids as $k=>$v){
    $sid=getsid();
    $fileid=getfileid($v,$data->data[0]->seed);
    $one=($data->data[0]->segs->$k);
    if($k == 'flv' || $k == 'mp4') return "http://f.youku.com/player/getflvpath/sid/{$sid}_00/st/{$k}/fileid/{$fileid}?k={$one[0]->k}";
    continue;
    }
} 
function get_curl_contents($url, $second = 5){
    if(!function_exists('curl_init')) die('php.ini未开启php_curl.dll');
    $c = curl_init();
    curl_setopt($c,curlopt_url,$url);
    $useragent=$_server['http_user_agent'];
    curl_setopt($c,curlopt_useragent,$useragent);
    curl_setopt($c,curlopt_header,0);
    curl_setopt($c,curlopt_timeout,$second);
    curl_setopt($c,curlopt_returntransfer, true);
    $cnt = curl_exec($c);
    $cnt=mb_check_encoding($cnt,'utf-8')?iconv('gbk','utf-8//ignore',$cnt):$cnt; //字符编码转换
    curl_close($c);
    return $cnt;
}
function getsid() {
    $sid = time().(rand(0,9000)+10000);
    return $sid;
}
function getkey($key1,$key2){
    $a = hexdec($key1);
    $b = $a ^ 0xa55aa5a5;
    $b = dechex($b);
    return $key2.$b;
}
function getfileid($fileid,$seed) {
    $mixed = getmixstring($seed);
    $ids = explode("*",$fileid);
    unset($ids[count($ids)-1]);
    $realid = "";
    for ($i=0;$i < count($ids);++$i) {
    $idx = $ids[$i];
    $realid .= substr($mixed,$idx,1);
    }
    return $realid;
}
function getmixstring($seed) {
    $mixed = "";
    $source = "abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz/\\:._-1234567890";
    $len = strlen($source);
    for($i=0;$i< $len;++$i){
    $seed = ($seed * 211 + 30031) % 65536;
    $index = ($seed / 65536 * strlen($source));
    $c = substr($source,$index,1);
    $mixed .= $c;
    $source = str_replace($c, "",$source);
    }
    return $mixed;
}
?>