Possible encoding problem using PHP-7 Sockets as WebSocket Server - php

Question

When trying to use PHP7.3 as SocketServer for WebSockets I encounter a problem where a message send from Firefox come out the socket all messed up. And always differently.
However, messages send from PHP to Firefox are fine.
For example:
socket.onopen = function(e)
{
e.target.send(JSON.stringify({"sessionid" : "5e8a2f30a164e", "sockid" : "5e8a5c8cd99e6"}));
}
one time becomes
)'JR9ZT#GN.Fx+/9JL#
hL+J)/
Z
next time it's
ZXC!+&)1,4<a`m&bj%i9rl=av+,91'xzv?9v9;'c=ux
Clientrequest:
GET / HTTP/1.1
Host: 192.168.5.54:8089
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:74.0) Gecko/20100101 Firefox/74.0
Accept: */*
Accept-Language: de,en-US;q=0.7,en;q=0.3
Accept-Encoding: gzip, deflate
Sec-WebSocket-Version: 13
Origin: http://192.168.5.54
Sec-WebSocket-Extensions: permessage-deflate
Sec-WebSocket-Key: uhfFVS5mhYptk6FF8jl73g==
Connection: keep-alive, Upgrade
Cookie: XDEBUG_SESSION=XDEBUG_ECLIPSE
Pragma: no-cache
Cache-Control: no-cache
Upgrade: websocket
Servercode[shortend]:
$this->socket = socket_create(AF_INET, SOCK_STREAM, SOL_TCP)
$ret = socket_bind($this->socket, $this->host, $this->port);
$ret = socket_listen( $this->socket, 0 );
socket_set_nonblock($this->socket);
while ($this->isServer)
{
$connection = #socket_accept($this->socket);
[... forking for new connection cont in child]
}
Child:
socket_close($this->socket);
[...]
$request = socket_read($connection, 5000); //creates above client request
preg_match('#Sec-WebSocket-Key: (.*)\r\n#', $request, $matches);
$key = base64_encode(pack('H*', sha1($matches[1] . '258EAFA5-E914-47DA-95CA-C5AB0DC85B11')));
$headers = "HTTP/1.1 101 Switching Protocols\r\n";
$headers .= "Upgrade: websocket\r\n";
$headers .= "Connection: Upgrade\r\n";
$headers .= "Sec-WebSocket-Version: 13\r\n";
//$headers .= "Sec-WebSocket-Protocol: json\r\n";
$headers .= "Sec-WebSocket-Accept: $key\r\n\r\n";
socket_write($connection, $headers, strlen($headers));
require_once("objs/User.php");
$user = new User();
// Send messages into WebSocket in a loop.
socket_set_nonblock($connection);
while (true)
{
if(($msg = socket_read($connection, 5000)) === "")
{
die;
}
if(!empty($msg))
{
echo $msg."\n";
}
I'm at a loss here and would appreciate your help!

Answer 1

It turns out data send from client->server is always "masked" using WebSockets.
The function unmask($payload) from this post helped me solve the problem.