PHP VK audio unmask (decode extras)

perfect.php

<?php
//(js -> php) code. letter by letter

global $n, $i, $id;
$n = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMN0PQRSTUVWXYZO123456789+/=";
$id = 12345; //YOUR USER ID

$i = [
	'v' => function($e) {
		return strrev($e);
	},
	'r' => function($e, $t){
		global $n;
		$e = str_split($e);
		for ($o = $n . $n, $s = count($e); $s--;){
			$i = stripos($o, $e[$s]);
			if(~$i){
				$e[$s] = substr($o, $i - $t, 1);
			}
		}
		return implode("", $e);
	},
	's' => function($e, $t) {
		$n = strlen($e);
		if ($n) {
			$i = r($e, $t);
			$o = 0;
			$e = str_split($e);
			for (; ++$o < $n;){
				$p = array_splice($e, $i[$n - 1 - $o], 1, $e[$o]);
				$e[$o] = $p[0];
			}

			$e = implode("", $e);
		}

		return $e;
	},
	'i' => function($e, $t){
		global $i, $id;
		$k = $i['s'];
		return $k($e, $t ^ $id);
	},
];

function o() {
	return false;
}

function a($e){
	global $n;
	if (!$e || strlen($e) % 4 == 1) {
		return !1;
	}
	$s = 0;
	for ($o = 0, $a = "";$s < strlen($e);) {
		$i = $e[$s++];
		$i = strpos($n, $i);
		if ($i !== false) {
			$t = ($o % 4) ? 64 * $t + $i : $i;
			if ($o++ % 4) {
				$a .= chr(255 & $t >> (-2 * $o & 6));
			}
		}
	}

	return $a;
}

function r($e, $t) {
	$n = strlen($e);
	$i = [];
	if ($n) {
		$o = $n;
		$t = abs($t);
		for (; $o--;){
			$t = ($n * ($o + 1) ^ $t + $o) % $n;
			$i[$o] = $t;
		}
	}
	return $i;
}

function s($e){
	global $i;
	if (!o() && strpos($e, "audio_api_unavailable") !== false) {
		$t = explode("?extra=", $e);
		$t = $t[1];
		$t = explode("#", $t);
		$n = ("" === $t[1]) ? "" : a($t[1]);
		$t = a($t[0]);
		if (!is_string($n) || !$t){ return $e;}
		$n = $n ? explode(chr(9), $n) : [];
		for ($l = count($n); $l--;) {
			$r = explode(chr(11), $n[$l]);
			$s = array_splice($r, 0, 1, $t);
			$s = $s[0];
			if (!$i[$s]){ return $e; }
			$t = $i[$s](...$r);
		}
		if ($t && "http" === substr($t, 0, 4)){ return $t;}
	}
	return $e;
}


//For example
//EASY <><<><><> 
//$extra = s("https://m.vk.com/mp3/audio_api_unavailable.mp3?extra=encodevaluefromvk"); //Encode extra url -> Good extra url
//Or see -> test.php        

test.php

<?php
include_once(__DIR__ . "/perfect.php");

$email = ""; //Login
$pass = ""; //Pass

$auth_url = "https://m.vk.com";

if(array_key_exists("extra", $_GET)){

	header("Content-type: audio/mpeg");

	echo file_get_contents(urldecode($_GET['extra']));

}else {

	/* Auth .. Copied from stackoverflow */
	$ch = curl_init();
	curl_setopt($ch, CURLOPT_URL, $auth_url);
	curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, 0);
	curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, 0);
	curl_setopt($ch, CURLOPT_COOKIEJAR, 'cookie.txt');
	curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
	$login_page = curl_exec($ch);
	curl_close($ch);

	preg_match("/<form method=\"post\" action=\"([^\"]+)/", $login_page, $login_url);
	$login_url = $login_url[1];

	$ch = curl_init();
	curl_setopt($ch, CURLOPT_URL, $login_url);
	curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, 0);
	curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, 0);
	curl_setopt($ch, CURLOPT_POST, 1);
	curl_setopt($ch, CURLOPT_FOLLOWLOCATION, 1);
	curl_setopt($ch, CURLOPT_POSTFIELDS, ["email" => $email, "pass" => $pass]);
	curl_setopt($ch, CURLOPT_COOKIEFILE, 'cookie.txt');
	curl_setopt($ch, CURLOPT_COOKIEJAR, 'cookie.txt');
	curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
	curl_exec($ch);
	curl_close($ch);



	/* Get music */
	$ch = curl_init();
	curl_setopt($ch, CURLOPT_URL, "https://m.vk.com/audio");
	curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, 0);
	curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, 0);
	curl_setopt($ch, CURLOPT_FOLLOWLOCATION, 1);
	curl_setopt($ch, CURLOPT_HTTPHEADER, ['X-Requested-With: XMLHttpRequest']);
	curl_setopt($ch, CURLOPT_POST, 1);
	curl_setopt($ch, CURLOPT_POSTFIELDS, ["_ajax" => 1, 'q' => $_GET['search']]);
	curl_setopt($ch, CURLOPT_COOKIEFILE, 'cookie.txt');
	curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
	$page = curl_exec($ch);
	curl_close($ch);

	$html = json_decode($page, true);
	$html = $html[3][0];
	$html = mb_convert_encoding($html, "UTF-8", "windows-1251");

	preg_match_all('/<span class="ai_title">(.+?)<\/span>/', $html, $titles);
	$titles = $titles[1];

	preg_match_all('/<span class="ai_artist">(.+?)<\/span>/', $html, $artists);
	$artists = $artists[1];

	//Get extras
	preg_match_all('/"https:\/\/m\.vk\.com\/mp3\/audio_api_unavailable\.mp3\?extra=([^"]+)/', $html, $extras);
	$extras = $extras[1];

	$result = array();

	foreach ($titles as $k => $title) {

		$result[] = array(
			"title" => strip_tags($title),
			"artist" => strip_tags($artists[$k]),
			"extra" => s("https://m.vk.com/mp3/audio_api_unavailable.mp3?extra=" . $extras[$k]) //Decooooooode
		);


	}

	/* Html */

	?>
	<!doctype html>
	<html lang="ru">
	<head>
		<meta charset="windows-1251">
		<title>Document</title>
	</head>
	<body>

	<?php

	echo "<table>";

	foreach ($result as $val) {

		echo "<tr>";

		echo("<td>" . mb_convert_encoding($val['title'], "CP1251", "UTF8") . "</td><td>" . mb_convert_encoding($val['artist'], "CP1251", "UTF8") . "</td><td><a href='" . ("?extra=" . $val['extra']) . "'>Получить</a></td>");

		echo "</tr>";

	}

	echo "</table>";

	?>
	</body>
	</html>

	<?php

}