=======================================
PHP Websockets Letsencrypt
=======================================

A quick introduction to test php websockets with letsencrypt.

1. create and run listener on the command line.
2. create and open the client web page in a browser.


=======================================
ed /non/web/directory/socket.php
---------------------------------------

<?php
error_reporting(E_ALL);

if(php_sapi_name() != 'cli') {
  exit('nope');
}

$path = '/usr/local/etc/letsencrypt/live/www.domain.com/';
$host = 'www.domain.com';
$port = 1234;
$transport = 'tlsv1.2';
$ssl = [
  'ssl' => [
    'local_cert'          => $path.'cert.pem',      // SSL Certificate
    'local_pk'            => $path.'privkey.pem',   // SSL Keyfile
    'disable_compression' => true,                  // TLS compression attack vulnerability
    'verify_peer'         => false,                 // Set this to true if acting as an SSL client
    'ssltransport'        => $transport,            // Transport Methods such as 'tlsv1.1', tlsv1.2'
  ]
];
$ssl_context = stream_context_create($ssl);
$server = stream_socket_server($transport.'://'.$host.':'.$port, $errno, $errstr, STREAM_SERVER_BIND|STREAM_SERVER_LISTEN, $ssl_context);
if(!$server) {
  exit($errstr.' ('.$errno.')');
}
$clients = array($server);
$write  = NULL;
$except = NULL;
$seconds = 10;

while(true) {
  $changed = $clients;
  stream_select($changed, $write, $except, $seconds);
  if(in_array($server, $changed)) {
    $client = @stream_socket_accept($server);
    if(!$client) {
      continue;
    }
    $clients[] = $client;
    $ip = stream_socket_get_name($client, true);
    print('New Client connected from '.$ip.PHP_EOL);

    stream_set_blocking($client, true);
    $headers = fread($client, 1500);
    handshake($client, $headers, $host, $port);
    stream_set_blocking($client, false);

    send_message($clients, mask($ip.' connected'));
    $found_socket = array_search($server, $changed);
    unset($changed[$found_socket]);
  }
  foreach($changed as $changed_socket) {
    $ip = stream_socket_get_name($changed_socket, true);
    $buffer = stream_get_contents($changed_socket);
    if($buffer == false) {
      print('Client Disconnected from '.$ip.PHP_EOL);
      @fclose($changed_socket);
      $found_socket = array_search($changed_socket, $clients);
      unset($clients[$found_socket]);
    }
    $unmasked = unmask($buffer);
    if($unmasked != '') {
      print(PHP_EOL.'Received a Message from '.$ip.':'.PHP_EOL.$unmasked.PHP_EOL);
    }
    $response = mask($unmasked);

    send_message($clients, $response);
  }
}
fclose($server);

function unmask($text) {
  $length = @ord($text[1]) & 127;
  if($length == 126) {
    $masks = substr($text, 4, 4);
    $data  = substr($text, 8);
  } elseif($length == 127) {
    $masks = substr($text, 10, 4);
    $data  = substr($text, 14);
  } else {
    $masks = substr($text, 2, 4);
    $data  = substr($text, 6);
  }
  $text = '';
  for($i = 0; $i < strlen($data); ++$i) {
    $text .= $data[$i] ^ $masks[$i % 4];
  }
  return $text;
}

function mask($text) {
  $b1 = 0x80 | (0x1 & 0x0f);
  $length = strlen($text);
  if($length <= 125) {
    $header = pack('CC', $b1, $length);
  } elseif($length > 125 && $length < 65536) {
    $header = pack('CCn', $b1, 126, $length);
  } elseif($length >= 65536) {
    $header = pack('CCNN', $b1, 127, $length);
  }
  return $header.$text;
}

function handshake($client, $rcvd, $host, $port) {
  $headers = array();
  $lines = preg_split('/\r\n/', $rcvd);
  foreach($lines as $line) {
    $line = rtrim($line);
    if(preg_match('/\A(\S+): (.*)\z/', $line, $matches)) {
      $headers[$matches[1]] = $matches[2];
    }
  }
  if(isset($headers['Sec-WebSocket-Key'])) {
    $secKey = $headers['Sec-WebSocket-Key'];
    $secAccept = base64_encode(pack('H*', sha1($secKey.'258EAFA5-E914-47DA-95CA-C5AB0DC85B11')));
    // hand shaking header
    $upgrade = 'HTTP/1.1 101 Web Socket Protocol Handshake'.PHP_EOL.
    'Upgrade: websocket'.PHP_EOL.
    'Connection: Upgrade'.PHP_EOL.
    'WebSocket-Origin: '.$host.PHP_EOL.
    'WebSocket-Location: wss://'.$host.':'.$port.PHP_EOL.
    'Sec-WebSocket-Version: 13'.PHP_EOL.
    'Sec-WebSocket-Accept: '.$secAccept.PHP_EOL.PHP_EOL;
    fwrite($client, $upgrade);
  }
}

function send_message($clients, $msg) {
  foreach($clients as $changed_socket) {
    @fwrite($changed_socket, $msg);
  }
}
?>


=======================================
ed /path/to/site/htdocs/sockettest.php
---------------------------------------

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <link rel="shortcut icon" href="favicon.ico">
    <title>socket test</title>
    <link rel="stylesheet" href="vendor/bootstrap-5.3.3-dist/css/bootstrap.min.css">
  </head>
  <body>
    <div class="container py-3">
      <form id="form">
        <fieldset>
          <div class="row g-1">
            <div class="col-4">
              <input type="text" class="form-control" id="input" placeholder="enter something" required>
            </div>
            <div class="col-2">
              <button type="submit" class="btn btn-primary" id="submit">Send</button>
            </div>
          </div>
        </fieldset>
      </form>
      <div class="mt-2" id="open">&nbsp;</div>
      <div class="mt-2" id="send">&nbsp;</div>
      <div class="mt-2" id="message">&nbsp;</div>
      <div class="mt-2" id="close">&nbsp;</div>
      <div class="mt-2" id="error">&nbsp;</div>
    </div>
    <script src="vendor/jquery/jquery.min.js"></script>
    <script src="vendor/bootstrap-5.3.3-dist/js/bootstrap.bundle.min.js"></script>
    <script>
var message = '';
var socket = new WebSocket('wss://www.domain.com:1234');
socket.onerror = function(event) {
  $('#error').html(event.data);
};
socket.onopen = function(event) {
  $('#open').html('Connection established');
};
socket.onmessage = function(event) {
  message += event.data+'<br>';
  $('#message').html('Received: '+message);
};
socket.onclose = function(event) {
  if(event.wasClean) {
    $('#close').html('Connection closed cleanly, code='+event.code+' reason='+event.reason);
  } else {
    $('#close').html('Connection died');
  };
};
$(document).on('submit', '#form', function(event) {
  var send = $('#input').val();
  socket.send(send);
  $('#send').html('Send: '+send);
  $('#input').val('');
  return false;
});
    </script>
  </body>
</html>


=======================================
Start the listener on the server
---------------------------------------

root@server:~ # php /non/web/directory/socket.php


=======================================
Connect to the listener
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https://www.domain.com:1234/sockettest.php


=======================================
done
=======================================