<?php

/**

 * PHPMailer RFC821 SMTP email transport class.

 * PHP Version 5.5.

 *

 * @see       https://github.com/PHPMailer/PHPMailer/ The PHPMailer GitHub project

 *

 * @author    Marcus Bointon (Synchro/coolbru) <phpmailer@synchromedia.co.uk>

 * @author    Jim Jagielski (jimjag) <jimjag@gmail.com>

 * @author    Andy Prevost (codeworxtech) <codeworxtech@users.sourceforge.net>

 * @author    Brent R. Matzelle (original founder)

 * @copyright 2012 - 2019 Marcus Bointon

 * @copyright 2010 - 2012 Jim Jagielski

 * @copyright 2004 - 2009 Andy Prevost

 * @license   http://www.gnu.org/copyleft/lesser.html GNU Lesser General Public License

 * @note      This program is distributed in the hope that it will be useful - WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.

 */

namespace PHPMailer\PHPMailer;

/**

 * PHPMailer RFC821 SMTP email transport class.

 * Implements RFC 821 SMTP commands and provides some utility methods for sending mail to an SMTP server.

 *

 * @author Chris Ryan

 * @author Marcus Bointon <phpmailer@synchromedia.co.uk>

 */

class SMTP

{

    /**

     * The PHPMailer SMTP version number.

     *

     * @var string

     */

    const VERSION = '6.1.6';

    /**

     * SMTP line break constant.

     *

     * @var string

     */

    const LE = "\r\n";

    /**

     * The SMTP port to use if one is not specified.

     *

     * @var int

     */

    const DEFAULT_PORT = 25;

    /**

     * The maximum line length allowed by RFC 5321 section 4.5.3.1.6,

     * *excluding* a trailing CRLF break.

     *

     * @see https://tools.ietf.org/html/rfc5321#section-4.5.3.1.6

     *

     * @var int

     */

    const MAX_LINE_LENGTH = 998;

    /**

     * The maximum line length allowed for replies in RFC 5321 section 4.5.3.1.5,

     * *including* a trailing CRLF line break.

     *

     * @see https://tools.ietf.org/html/rfc5321#section-4.5.3.1.5

     *

     * @var int

     */

    const MAX_REPLY_LENGTH = 512;

    /**

     * Debug level for no output.

     *

     * @var int

     */

    const DEBUG_OFF = 0;

    /**

     * Debug level to show client -> server messages.

     *

     * @var int

     */

    const DEBUG_CLIENT = 1;

    /**

     * Debug level to show client -> server and server -> client messages.

     *

     * @var int

     */

    const DEBUG_SERVER = 2;

    /**

     * Debug level to show connection status, client -> server and server -> client messages.

     *

     * @var int

     */

    const DEBUG_CONNECTION = 3;

    /**

     * Debug level to show all messages.

     *

     * @var int

     */

    const DEBUG_LOWLEVEL = 4;

    /**

     * Debug output level.

     * Options:

     * * self::DEBUG_OFF (`0`) No debug output, default

     * * self::DEBUG_CLIENT (`1`) Client commands

     * * self::DEBUG_SERVER (`2`) Client commands and server responses

     * * self::DEBUG_CONNECTION (`3`) As DEBUG_SERVER plus connection status

     * * self::DEBUG_LOWLEVEL (`4`) Low-level data output, all messages.

     *

     * @var int

     */

    public $do_debug = self::DEBUG_OFF;

    /**

     * How to handle debug output.

     * Options:

     * * `echo` Output plain-text as-is, appropriate for CLI

     * * `html` Output escaped, line breaks converted to `<br>`, appropriate for browser output

     * * `error_log` Output to error log as configured in php.ini

     * Alternatively, you can provide a callable expecting two params: a message string and the debug level:

     *

     * ```php

     * $smtp->Debugoutput = function($str, $level) {echo "debug level $level; message: $str";};

     * ```

     *

     * Alternatively, you can pass in an instance of a PSR-3 compatible logger, though only `debug`

     * level output is used:

     *

     * ```php

     * $mail->Debugoutput = new myPsr3Logger;

     * ```

     *

     * @var string|callable|\Psr\Log\LoggerInterface

     */

    public $Debugoutput = 'echo';

    /**

     * Whether to use VERP.

     *

     * @see http://en.wikipedia.org/wiki/Variable_envelope_return_path

     * @see http://www.postfix.org/VERP_README.html Info on VERP

     *

     * @var bool

     */

    public $do_verp = false;

    /**

     * The timeout value for connection, in seconds.

     * Default of 5 minutes (300sec) is from RFC2821 section 4.5.3.2.

     * This needs to be quite high to function correctly with hosts using greetdelay as an anti-spam measure.

     *

     * @see http://tools.ietf.org/html/rfc2821#section-4.5.3.2

     *

     * @var int

     */

    public $Timeout = 300;

    /**

     * How long to wait for commands to complete, in seconds.

     * Default of 5 minutes (300sec) is from RFC2821 section 4.5.3.2.

     *

     * @var int

     */

    public $Timelimit = 300;

    /**

     * Patterns to extract an SMTP transaction id from reply to a DATA command.

     * The first capture group in each regex will be used as the ID.

     * MS ESMTP returns the message ID, which may not be correct for internal tracking.

     *

     * @var string[]

     */

    protected $smtp_transaction_id_patterns = [

        'exim' => '/[\d]{3} OK id=(.*)/',

        'sendmail' => '/[\d]{3} 2.0.0 (.*) Message/',

        'postfix' => '/[\d]{3} 2.0.0 Ok: queued as (.*)/',

        'Microsoft_ESMTP' => '/[0-9]{3} 2.[\d].0 (.*)@(?:.*) Queued mail for delivery/',

        'Amazon_SES' => '/[\d]{3} Ok (.*)/',

        'SendGrid' => '/[\d]{3} Ok: queued as (.*)/',

        'CampaignMonitor' => '/[\d]{3} 2.0.0 OK:([a-zA-Z\d]{48})/',

    ];

    /**

     * The last transaction ID issued in response to a DATA command,

     * if one was detected.

     *

     * @var string|bool|null

     */

    protected $last_smtp_transaction_id;

    /**

     * The socket for the server connection.

     *

     * @var ?resource

     */

    protected $smtp_conn;

    /**

     * Error information, if any, for the last SMTP command.

     *

     * @var array

     */

    protected $error = [

        'error' => '',

        'detail' => '',

        'smtp_code' => '',

        'smtp_code_ex' => '',

    ];

    /**

     * The reply the server sent to us for HELO.

     * If null, no HELO string has yet been received.

     *

     * @var string|null

     */

    protected $helo_rply;

    /**

     * The set of SMTP extensions sent in reply to EHLO command.

     * Indexes of the array are extension names.

     * Value at index 'HELO' or 'EHLO' (according to command that was sent)

     * represents the server name. In case of HELO it is the only element of the array.

     * Other values can be boolean TRUE or an array containing extension options.

     * If null, no HELO/EHLO string has yet been received.

     *

     * @var array|null

     */

    protected $server_caps;

    /**

     * The most recent reply received from the server.

     *

     * @var string

     */

    protected $last_reply = '';

    /**

     * Output debugging info via a user-selected method.

     *

     * @param string $str   Debug string to output

     * @param int    $level The debug level of this message; see DEBUG_* constants

     *

     * @see SMTP::$Debugoutput

     * @see SMTP::$do_debug

     */

    protected function edebug($str, $level = 0)

    {

        if ($level > $this->do_debug) {

            return;

        }

        //Is this a PSR-3 logger?

        if ($this->Debugoutput instanceof \Psr\Log\LoggerInterface) {

            $this->Debugoutput->debug($str);

            return;

        }

        //Avoid clash with built-in function names

        if (is_callable($this->Debugoutput) && !in_array($this->Debugoutput, ['error_log', 'html', 'echo'])) {

            call_user_func($this->Debugoutput, $str, $level);

            return;

        }

        switch ($this->Debugoutput) {

            case 'error_log':

                //Don't output, just log

                error_log($str);

                break;

            case 'html':

                //Cleans up output a bit for a better looking, HTML-safe output

                echo gmdate('Y-m-d H:i:s'), ' ', htmlentities(

                    preg_replace('/[\r\n]+/', '', $str),

                    ENT_QUOTES,

                    'UTF-8'

                ), "<br>\n";

                break;

            case 'echo':

            default:

                //Normalize line breaks

                $str = preg_replace('/\r\n|\r/m', "\n", $str);

                echo gmdate('Y-m-d H:i:s'),

                "\t",

                    //Trim trailing space

                trim(

                    //Indent for readability, except for trailing break

                    str_replace(

                        "\n",

                        "\n                   \t                  ",

                        trim($str)

                    )

                ),

                "\n";

        }

    }

    /**

     * Connect to an SMTP server.

     *

     * @param string $host    SMTP server IP or host name

     * @param int    $port    The port number to connect to

     * @param int    $timeout How long to wait for the connection to open

     * @param array  $options An array of options for stream_context_create()

     *

     * @return bool

     */

    public function connect($host, $port = null, $timeout = 30, $options = [])

    {

        static $streamok;

        //This is enabled by default since 5.0.0 but some providers disable it

        //Check this once and cache the result

        if (null === $streamok) {

            $streamok = function_exists('stream_socket_client');

        }

        // Clear errors to avoid confusion

        $this->setError('');

        // Make sure we are __not__ connected

        if ($this->connected()) {

            // Already connected, generate error

            $this->setError('Already connected to a server');

            return false;

        }

        if (empty($port)) {

            $port = self::DEFAULT_PORT;

        }

        // Connect to the SMTP server

        $this->edebug(

            "Connection: opening to $host:$port, timeout=$timeout, options=" .

            (count($options) > 0 ? var_export($options, true) : 'array()'),

            self::DEBUG_CONNECTION

        );

        $errno = 0;

        $errstr = '';

        if ($streamok) {

            $socket_context = stream_context_create($options);

            set_error_handler([$this, 'errorHandler']);

            $this->smtp_conn = stream_socket_client(

                $host . ':' . $port,

                $errno,

                $errstr,

                $timeout,

                STREAM_CLIENT_CONNECT,

                $socket_context

            );

            restore_error_handler();

        } else {

            //Fall back to fsockopen which should work in more places, but is missing some features

            $this->edebug(

                'Connection: stream_socket_client not available, falling back to fsockopen',

                self::DEBUG_CONNECTION

            );

            set_error_handler([$this, 'errorHandler']);

            $this->smtp_conn = fsockopen(

                $host,

                $port,

                $errno,

                $errstr,

                $timeout

            );

            restore_error_handler();

        }

        // Verify we connected properly

        if (!is_resource($this->smtp_conn)) {

            $this->setError(

                'Failed to connect to server',

                '',

                (string) $errno,

                $errstr

            );

            $this->edebug(

                'SMTP ERROR: ' . $this->error['error']

                . ": $errstr ($errno)",

                self::DEBUG_CLIENT

            );

            return false;

        }

        $this->edebug('Connection: opened', self::DEBUG_CONNECTION);

        // SMTP server can take longer to respond, give longer timeout for first read

        // Windows does not have support for this timeout function

        if (strpos(PHP_OS, 'WIN') !== 0) {

            $max = (int) ini_get('max_execution_time');

            // Don't bother if unlimited

            if (0 !== $max && $timeout > $max) {

                @set_time_limit($timeout);

            }

            stream_set_timeout($this->smtp_conn, $timeout, 0);

        }

        // Get any announcement

        $announce = $this->get_lines();

        $this->edebug('SERVER -> CLIENT: ' . $announce, self::DEBUG_SERVER);

        return true;

    }

    /**

     * Initiate a TLS (encrypted) session.

     *

     * @return bool

     */

    public function startTLS()

    {

        if (!$this->sendCommand('STARTTLS', 'STARTTLS', 220)) {

            return false;

        }

        //Allow the best TLS version(s) we can

        $crypto_method = STREAM_CRYPTO_METHOD_TLS_CLIENT;

        //PHP 5.6.7 dropped inclusion of TLS 1.1 and 1.2 in STREAM_CRYPTO_METHOD_TLS_CLIENT

        //so add them back in manually if we can

        if (defined('STREAM_CRYPTO_METHOD_TLSv1_2_CLIENT')) {

            $crypto_method |= STREAM_CRYPTO_METHOD_TLSv1_2_CLIENT;

            $crypto_method |= STREAM_CRYPTO_METHOD_TLSv1_1_CLIENT;

        }

        // Begin encrypted connection

        set_error_handler([$this, 'errorHandler']);

        $crypto_ok = stream_socket_enable_crypto(

            $this->smtp_conn,

            true,

            $crypto_method

        );

        restore_error_handler();

        return (bool) $crypto_ok;

    }

    /**

     * Perform SMTP authentication.

     * Must be run after hello().

     *

     * @see    hello()

     *

     * @param string $username The user name

     * @param string $password The password

     * @param string $authtype The auth type (CRAM-MD5, PLAIN, LOGIN, XOAUTH2)

     * @param OAuth  $OAuth    An optional OAuth instance for XOAUTH2 authentication

     *

     * @return bool True if successfully authenticated

     */

    public function authenticate(

        $username,

        $password,

        $authtype = null,

        $OAuth = null

    ) {

        if (!$this->server_caps) {

            $this->setError('Authentication is not allowed before HELO/EHLO');

            return false;

        }

        if (array_key_exists('EHLO', $this->server_caps)) {

            // SMTP extensions are available; try to find a proper authentication method