<?php
class BaseProxy {
    protected $addr = NULL;
    protected $port = NULL;
    protected $debug = false;
    protected $clients = array();
    protected $buffer = array();
    public $maxConnections = 50;
    public $pid = -1;
    
    function __construct($addr='0.0.0.0',$port='8000') {
        $this->debug = defined('DEBUG') ? DEBUG : false;
        $this->log('__construct()');
        set_time_limit(0);
        if (defined('THREADING') && (THREADING == true)) {
            if (!extension_loaded('pcntl')) {
                $prefix = (PHP_SHLIB_SUFFIX === 'dll') ? 'php_' : '';
                if (!@dl($prefix . 'pcntl.' . PHP_SHLIB_SUFFIX)) $this->pid = -2;
            }
        }
        else {
            $this->pid = -2;
        }
        $this->addr = $addr;
        $this->port = $port;
        
        try {
            $this->socket = socket_create(AF_INET,SOCK_STREAM,SOL_TCP);
            if ($this->socket === false) $this->halt('Unable to create main socket');
            socket_set_option($this->socket,SOL_SOCKET,SO_REUSEADDR,1);
            if (!socket_set_nonblock($this->socket)) $this->log($this->lastError());
            if (!socket_bind($this->socket,$this->addr,$this->port)) $this->halt($this->lastError());
            socket_getsockname($this->socket,$this->addr,$this->port);
            $this->log(sprintf('Starting HTTP Proxy on %s port %s',$this->addr,$this->port));
            if (!socket_listen($this->socket)) $this->halt($this->lastError());
        }
        catch (Exception $e) {
            $this->halt($e->getMessage());
        }
        $this->main();
    }
    
    function __destruct() {
        $this->log('__destruct()');
        if ($this->pid !== 0) {
            socket_close($this->socket);
            foreach ($this->clients as $s) $this->destroy($s);
            $this->clients = array();
            $this->buffer = array();
        }
        posix_kill(getmypid(),9);
    }
    
    public function lastError($s=NULL) {
        if ($s === NULL) $s =& $this->socket;
        return @socket_strerror(socket_last_error($s));
    }
    
    public function main() {
        $write = NULL;
        while (true) {
            if ((count($this->clients) <= $this->maxConnections) && ($s = @socket_accept($this->socket))) {
                socket_getpeername($s,$raddr,$rport); 
                $this->log("Received Connection from $raddr:$rport");
                $this->buffer[$s] = '';
                if (!socket_set_block($s)) $this->log($this->lastError($s));
                if (!socket_set_option($s,SOL_SOCKET,SO_RCVTIMEO,array('sec'=>10,'usec'=>0))) $this->log($this->lastError($s));
                if (!socket_set_option($s,SOL_SOCKET,SO_SNDTIMEO,array('sec'=>10,'usec'=>0))) $this->log($this->lastError($s));
                $this->clients[$s] = $s;
                $this->log(sprintf('%s active connections',count($this->clients)));
            }
            $read = $except = array_values($this->clients);
            if (@socket_select($read,$write,$except,0)) {
                foreach ($read as $s) {
                    $this->read($s);
                }
                foreach ($except as $s) {
                    $this->log($this->lastError($s));
                    $this->destroy($s);
                }
            }
            usleep(100000);
        }
    }
    
    protected function destroy($s) {
        socket_close($s);
        unset($this->clients[$s]);
        unset($this->buffer[$s]);
    }
    
    protected function read($s) {
        $this->buffer[$s] .= socket_read($s,8192,PHP_BINARY_READ);
        if (preg_match('#\r\n\r\n$#s',$this->buffer[$s])) {
            if (trim($this->buffer[$s]) == 'QUIT') exit;
            unset($this->clients[$s]);
            if ($this->pid != -2) $this->pid = pcntl_fork();
            if ($this->pid <= 0) $this->handle($s);
        }
    }
    
    protected function handle($s) {
        $req = preg_split('#\r\n#s',$this->buffer[$s],-1);
        unset($this->buffer[$s]);
        list($method,$url,$protocol) = sscanf(array_shift($req),'%s %s %s');
        $this->log("handle() :: $method $url $protocol");
        switch ($method) {
            case 'CONNECT':
                $this->do_CONNECT($s,$url,$protocol,$req);
                break;
            case 'GET':
            case 'POST':
            case 'DELETE':
            case 'PUT':
            case 'HEAD':
                $this->do_GET($s,$method,$url,$protocol,$req);
                break;
            default:
                $this->do_ERROR($s,'Not Implemented',501,$protocol,$req);
                break;
        }
        $this->log('handle() :: done');
        if ($this->pid === 0) {
            $this->log('Killing child process');
            posix_kill(getmypid(),9);
            exit;
        }
    }
    
    protected function do_ERROR($s,$errmsg,$errcode,$protocol,$req) {
        $this->log(sprintf('do_ERROR(%s,%s)',$errmsg,$errcode));
        $html = "<html><head><title>$errcode $errmsg</title></head><body><h1>$errmsg</h1></body></html>";
        $length = strlen($html);
        socket_write($s,"Status: $errcode $errmsg\r\nContent-Type: text/html\r\nContent-Length: $length\r\n\r\n$html");
        $this->destroy($s);
    }
    
    protected function do_CONNECT($s,$url,$protocol,$req) {
        $this->log(sprintf('do_CONNECT(%s)',$url));
        list($host,$port) = explode(':',$url,2);
        $d = socket_create(AF_INET,SOCK_STREAM,SOL_TCP);
        if (($d === false) || !@socket_connect($d,$host,$port)) {
            if ($d) $this->log($this->lastError($d));
            @socket_close($d);
            $this->do_ERROR($s,'Not Found',404,$protocol,$req);
        }
        else {
            socket_write($s,"$protocol 200 Connection established\r\n\r\n");
            $this->read_write($s,$d,30);
        }        
    }
    
    protected function do_GET($s,$method,$url,$protocol,$req) {
        $this->log(sprintf('do_GET(%s,%s)',$method,$url));
        @extract(parse_url($url));
        if ((strtolower($scheme) != 'http') || $fragment || !$host || !$path) {
            $this->do_ERROR($s,'Bad Request',400,$protocol,$req);
        }
        else {
            if (!$port) $port = 80;
            $d = socket_create(AF_INET,SOCK_STREAM,SOL_TCP);
            if (($d == false) || !@socket_connect($d,$host,$port)) {
                if ($d) $this->log($this->lastError($d));
                @socket_close($d);
                $this->do_ERROR($s,'Not Found',404,$protocol,$req);
            }
            else {
                // todo : auth requests
                if ($query) $query = "?$query";
                socket_write($d,sprintf("%s %s %s\r\n",$method,$path.$query,$protocol));
                foreach ($req as $h) {
                    if (empty($h)) socket_write($d,"Connection: close\r\n\r\n");
                    elseif (!preg_match('#^(Proxy-Connection)|(Connection ?:)#si',$h)) socket_write($d,"$h\r\n");
                }
                $this->read_write($s,$d);
            }
        }
    }
    
    protected function read_write($client,$server,$max_idling=20) {
        $this->log('read_write()');
        if (!socket_set_block($server)) $this->log($this->lastError($server));
        if (!socket_set_option($server,SOL_SOCKET,SO_RCVTIMEO,array('sec'=>10,'usec'=>0))) $this->log($this->lastError($server));
        if (!socket_set_option($server,SOL_SOCKET,SO_SNDTIMEO,array('sec'=>10,'usec'=>0))) $this->log($this->lastError($server));
        $n = 0;
        $write = NULL;
        while (true) {
            $n++;
            $read = $except = array($client,$server);
            if (socket_select($read,$write,$except,3,0)) {
                foreach ($read as $in) {
                    $data = @socket_read($in,8192,PHP_BINARY_READ);
                    if ($data === false) {
                        $this->log($this->lastError($in));
                        break;
                    }
                    elseif ($data) {
                        if (!@socket_write($in == $client ? $server : $client,$data)) {
                            $this->log($this->lastError($in == $client ? $server : $client));
                            break;
                        }
                        else $n = 0;
                    }
                }
                if (count($except)) {
                    foreach ($except as $e) $this->log($this->lastError($e));
                    break;
                }
            }
            if ($n >= $max_idling) break;
        }
        $this->destroy($client);
        $this->destroy($server);
    }
    
    protected function log($msg) {
        if ($this->debug) printf("%s %s [PID=%s/%s]\n",date('Y-m-d H:i:s'),$msg,getmypid(),$this->pid);
    }
    
    protected function halt($errmsg) {
        die("$errmsg\n");
    }
}

define('DEBUG',true);
define('THREADING',true);

$proxy = $argc == 3 ? new BaseProxy($argv[1],$argv[2]) : new BaseProxy;
?>