Attempt to use an SSH tunnel to connect to MySQL on a remote host

Tunnel.php

<?php
/***
Based off code from: 
https://www.experts-exchange.com/questions/26619790/Connect-to-Mysql-through-PHP-ssh2-tunnel.html

Example usage: User/Pass Based Auth MySQL Proxy
-----------------------------------------------
$user_pass_config = array(
	'user' => 'username',
	'pass' => 'password',
	'host' => 'myserver.com',
	'port' => 22
);
$local_proxy_port = 3307;
$remote_proxy_host = '127.0.0.1';
$remote_proxy_port = 3306;
$tunnel = new Tunnel();
$tunnel->set_config( $user_pass_config );
$tunnel->proxy( $local_proxy_port, $remote_proxy_host, $remote_proxy_port );
// We now have a tcp server on 127.0.0.1 port 3307 which is proxying, over ssh, to 127.0.0.1 port 3306 on myserver.com

**/
class Tunnel {

	public $host        = NULL; // SSH Host
	public $port        = 22;   // SSH Port
	public $user        = NULL; // Username
	public $pass        = NULL; // User Password
	
	private $conn        = NULL; // Resource: SSH2 connection
	private $tunnel      = NULL; // Resource: SSH2 tunnel
	private $socket      = NULL; // Local socket
	private $debug_array = [];   // Debug messages

	// -----------------------------------------------------------------------

	public function __construct(){ return $this; }

	// -----------------------------------------------------------------------

	public function set_config( $args = [] )
	{
		foreach( $args as $k => $v )
			$this->$k = $v;

		return $this;
	}

	// -----------------------------------------------------------------------

	public function proxy( $local_port, $remote_host, $remote_port )
	{
		if( ! $this->_connect_to_remote_server( $remote_host, $remote_port ) )
			return FALSE;

		if( ! $this->_create_local_socket( $local_port ) )
			return FALSE;

		$conn = @stream_socket_accept( $this->socket, 180 );

		stream_set_blocking( $conn, FALSE );

		while( ! feof($conn) && ! feof($this->socket) )
		{
			// Read from server to client
			if ( strlen( $data = @fread( $this->tunnel, 4096 ) ) ) {
				if ( FALSE === fwrite( $conn, $data ) )
					break;
			} else if ( strlen( $data = @fread( $conn, 4096 ) ) ) {
				if ( FALSE === fwrite( $this->tunnel, $data ) )
					break;
			} else {
				usleep( 5000 );
			}
		}
		@fclose( $conn );
		@fclose( $this->tunnel );
		return TRUE;
	}

	// -----------------------------------------------------------------------

	private function _connect_to_remote_server( $remote_host, $remote_port )
	{
		if( ! $this->_connect() ) return FALSE;
		if( $this->tunnel )
			return TRUE;
		$this->tunnel = fopen("ssh2.tunnel://$this->conn/$remote_host:$remote_port", 'r+');
		if( ! $this->tunnel OR ! is_resource( $this->tunnel ) )
		{
			$this->debug_array[] = "Failed Initializing Tunnel To $remote_host:$remote_port";
			return FALSE;
		}
		$this->debug_array[] = "Tunnel To $remote_host:$remote_port Initialized";
		stream_set_blocking( $this->tunnel, FALSE );
		return TRUE;
	}

	// -----------------------------------------------------------------------

	private function _connect()
	{
		if( $this->conn )
			return $this->conn;
		if( ! $this->host OR ! $this->port OR ! $this->user OR ! $this->pass )
			return FALSE;
		$this->conn = ssh2_connect( $this->host, $this->port );
		if( ! $this->conn )
		{
			$this->conn = NULL;
			$this->debug_array[] = "Could not connect to $this->host:$this->port";
			return FALSE;
		}
		$this->debug_array[] = "Connected to $this->host:$this->port";

		$auth = ssh2_auth_password( $this->conn, $this->user, $this->pass );
		if( ! $auth )
		{
			$this->conn = NULL;
			$this->debug_array[] = "Could not authenticate for user $this->user";
			return FALSE;
		}
		$this->debug_array[] = "Logged in as $this->user";
		return TRUE;
	}

	// -----------------------------------------------------------------------

	private function _create_local_socket( $port )
	{
		$this->socket = stream_socket_server( "tcp://127.0.0.1:$port", $errno, $errstr );		
		if( ! $this->socket )
		{
			$this->debug_array[] = "Failed creating socket server: $errstr ($errno)";
			return FALSE;
		}
		return TRUE;
	}

	// -----------------------------------------------------------------------

	public function halt()
	{
		$this->conn = NULL;
		@fclose( $this->tunnel );
		die('<pre>' . print_r( $this->debug_array, TRUE ) . '</pre>');
	}
	
	// -----------------------------------------------------------------------

}