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<?php
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$magic = 'TzGq';
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$tempdir = sys_get_temp_dir() . "/hop" . $magic;
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if(!is_dir($tempdir)){
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	mkdir($tempdir); //make sure it's there
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}
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//get url
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$url = $_SERVER["QUERY_STRING"];
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//like /path/hop.php?/uRIcksm_lOnGidENTifIEr
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//Looks for a file with a name or contents prefix, if found, send it and deletes it
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function findSendDelete($tempdir, $prefix, $one=true){
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	if($dh = opendir($tempdir)){
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		while(($file = readdir($dh)) !== false){
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			if(strpos($file, $prefix) !== 0){
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				continue;
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			}
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			readfile($tempdir."/".$file);
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			unlink($tempdir."/".$file);
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			if($one){
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				break;
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			}
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		}
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	}
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}
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//handle control
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if($url === "/control"){
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	if($_SERVER['REQUEST_METHOD'] === 'POST'){
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		//handle data for payload - save in a "down" file or the "init" file
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		$postdata = file_get_contents("php://input");
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		if(array_key_exists('HTTP_X_INIT', $_SERVER)){
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			$f = fopen($tempdir."/init", "w"); //only one init file
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		}else{
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			$prefix = "down_" . sha1($_SERVER['HTTP_X_URLFRAG']);
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			$f = fopen(tempnam($tempdir,$prefix), "w");
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		}
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		fwrite($f, $postdata);
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		fclose($f);
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	}else{
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		findSendDelete($tempdir, "up_", false);
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	}
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}else if($_SERVER['REQUEST_METHOD'] === 'POST'){
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	//get data
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	$postdata = file_get_contents("php://input");
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	//See if we should send anything down
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	if($postdata === "RECV\x00" || $postdata === "RECV"){
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		findSendDelete($tempdir, "down_" . sha1($url));
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		$fname = $tempdir . "/up_recv_" . sha1($url); //Only keep one RECV poll
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	}else{
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		$fname = tempnam($tempdir, "up_"); //actual data gets its own filename
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	}
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	//find free and write new file
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	$f = fopen($fname, "w");
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	fwrite($f, $magic);
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	//Little-endian pack length and data
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	$urlen = strlen($url);
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	fwrite($f, pack('V', $urlen));
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	fwrite($f, $url);
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	$postdatalen = strlen($postdata);
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	fwrite($f, pack('V', $postdatalen));
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	fwrite($f, $postdata);
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	fclose($f);
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//Initial query will be a GET and have a 12345 in it
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}else if(strpos($url, "12345") !== FALSE){
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	readfile($tempdir."/init");
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}
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