SMTP::getSMTPConnection( string $host, int $port = null, int $timeout = 30, array $options = [] ): false|resource

407    protected function getSMTPConnection($host, $port = null, $timeout = 30, $options = [])408    {409        static $streamok;410        //This is enabled by default since 5.0.0 but some providers disable it411        //Check this once and cache the result412        if (null === $streamok) {413            $streamok = function_exists('stream_socket_client');414        }415 416        $errno = 0;417        $errstr = '';418        if ($streamok) {419            $socket_context = stream_context_create($options);420            set_error_handler(function () {421                call_user_func_array([$this, 'errorHandler'], func_get_args());422            });423            $connection = stream_socket_client(424                $host . ':' . $port,425                $errno,426                $errstr,427                $timeout,428                STREAM_CLIENT_CONNECT,429                $socket_context430            );431        } else {432            //Fall back to fsockopen which should work in more places, but is missing some features433            $this->edebug(434                'Connection: stream_socket_client not available, falling back to fsockopen',435                self::DEBUG_CONNECTION436            );437            set_error_handler(function () {438                call_user_func_array([$this, 'errorHandler'], func_get_args());439            });440            $connection = fsockopen(441                $host,442                $port,443                $errno,444                $errstr,445                $timeout446            );447        }448        restore_error_handler();449 450        //Verify we connected properly451        if (!is_resource($connection)) {452            $this->setError(453                'Failed to connect to server',454                '',455                (string) $errno,456                $errstr457            );458            $this->edebug(459                'SMTP ERROR: ' . $this->error['error']460                . ": $errstr ($errno)",461                self::DEBUG_CLIENT462            );463 464            return false;465        }466 467        //SMTP server can take longer to respond, give longer timeout for first read468        //Windows does not have support for this timeout function469        if (strpos(PHP_OS, 'WIN') !== 0) {470            $max = (int)ini_get('max_execution_time');471            //Don't bother if unlimited, or if set_time_limit is disabled472            if (0 !== $max && $timeout > $max && strpos(ini_get('disable_functions'), 'set_time_limit') === false) {473                @set_time_limit($timeout);474            }475            stream_set_timeout($connection, $timeout, 0);476        }477 478        return $connection;479    }