class.smtp.php

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<?php
class SMTP
{
    const VERSION = '5.2.24';

    const CRLF = "\r\n";

    const DEFAULT_SMTP_PORT = 25;

    const MAX_LINE_LENGTH = 998;

    const DEBUG_OFF = 0;

    const DEBUG_CLIENT = 1;

    const DEBUG_SERVER = 2;

    const DEBUG_CONNECTION = 3;

    const DEBUG_LOWLEVEL = 4;

    public $Version = '5.2.24';

    public $SMTP_PORT = 25;

    public $CRLF = "\r\n";

    public $do_debug = self::DEBUG_OFF;

    public $Debugoutput = 'echo';

    public $do_verp = false;

    public $Timeout = 300;

    public $Timelimit = 300;

    protected $smtp_transaction_id_patterns = array(
        'exim' => '/[0-9]{3} OK id=(.*)/',
        'sendmail' => '/[0-9]{3} 2.0.0 (.*) Message/',
        'postfix' => '/[0-9]{3} 2.0.0 Ok: queued as (.*)/'
    );

    protected $smtp_conn;

    protected $error = array(
        'error' => '',
        'detail' => '',
        'smtp_code' => '',
        'smtp_code_ex' => ''
    );

    protected $helo_rply = null;

    protected $server_caps = null;

    protected $last_reply = '';

    protected function edebug($str, $level = 0)
    {
        if ($level > $this->do_debug) {
            return;
        }
        //Avoid clash with built-in function names
        if (!in_array($this->Debugoutput, array('error_log', 'html', 'echo')) and is_callable($this->Debugoutput)) {
            call_user_func($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|\n)/ms', "\n", $str);
                echo gmdate('Y-m-d H:i:s') . "\t" . str_replace(
                    "\n",
                    "\n                   \t                  ",
                    trim($str)
                ) . "\n";
        }
    }

    public function connect($host, $port = null, $timeout = 30, $options = array())
    {
        static $streamok;
        //This is enabled by default since 5.0.0 but some providers disable it
        //Check this once and cache the result
        if (is_null($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_SMTP_PORT;
        }
        // Connect to the SMTP server
        $this->edebug(
            "Connection: opening to $host:$port, timeout=$timeout, options=" .
            var_export($options, true),
            self::DEBUG_CONNECTION
        );
        $errno = 0;
        $errstr = '';
        if ($streamok) {
            $socket_context = stream_context_create($options);
            set_error_handler(array($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
            $this->edebug(
                "Connection: stream_socket_client not available, falling back to fsockopen",
                self::DEBUG_CONNECTION
            );
            set_error_handler(array($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',
                $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 (substr(PHP_OS, 0, 3) != 'WIN') {
            $max = ini_get('max_execution_time');
            // Don't bother if unlimited
            if ($max != 0 && $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;
    }

    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(array($this, 'errorHandler'));
        $crypto_ok = stream_socket_enable_crypto(
            $this->smtp_conn,
            true,
            $crypto_method
        );
        restore_error_handler();
        return $crypto_ok;
    }

    public function authenticate(
        $username,
        $password,
        $authtype = null,
        $realm = '',
        $workstation = '',
        $OAuth = null
    ) {
        if (!$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
            if (!array_key_exists('AUTH', $this->server_caps)) {
                $this->setError('Authentication is not allowed at this stage');
                // 'at this stage' means that auth may be allowed after the stage changes
                // e.g. after STARTTLS
                return false;
            }

            self::edebug('Auth method requested: ' . ($authtype ? $authtype : 'UNKNOWN'), self::DEBUG_LOWLEVEL);
            self::edebug(
                'Auth methods available on the server: ' . implode(',', $this->server_caps['AUTH']),
                self::DEBUG_LOWLEVEL
            );

            if (empty($authtype)) {
                foreach (array('CRAM-MD5', 'LOGIN', 'PLAIN', 'NTLM', 'XOAUTH2') as $method) {
                    if (in_array($method, $this->server_caps['AUTH'])) {
                        $authtype = $method;
                        break;
                    }
                }
                if (empty($authtype)) {
                    $this->setError('No supported authentication methods found');
                    return false;
                }
                self::edebug('Auth method selected: ' . $authtype, self::DEBUG_LOWLEVEL);
            }

            if (!in_array($authtype, $this->server_caps['AUTH'])) {
                $this->setError("The requested authentication method \"$authtype\" is not supported by the server");
                return false;
            }
        } elseif (empty($authtype)) {
            $authtype = 'LOGIN';
        }
        switch ($authtype) {
            case 'PLAIN':
                // Start authentication
                if (!$this->sendCommand('AUTH', 'AUTH PLAIN', 334)) {
                    return false;
                }
                // Send encoded username and password
                if (!$this->sendCommand(
                    'User & Password',
                    base64_encode("\0" . $username . "\0" . $password),
                    235
                )
                ) {
                    return false;
                }
                break;
            case 'LOGIN':
                // Start authentication
                if (!$this->sendCommand('AUTH', 'AUTH LOGIN', 334)) {
                    return false;
                }
                if (!$this->sendCommand("Username", base64_encode($username), 334)) {
                    return false;
                }
                if (!$this->sendCommand("Password", base64_encode($password), 235)) {
                    return false;
                }
                break;
            case 'XOAUTH2':
                //If the OAuth Instance is not set. Can be a case when PHPMailer is used
                //instead of PHPMailerOAuth
                if (is_null($OAuth)) {
                    return false;
                }
                $oauth = $OAuth->getOauth64();

                // Start authentication
                if (!$this->sendCommand('AUTH', 'AUTH XOAUTH2 ' . $oauth, 235)) {
                    return false;
                }
                break;
            case 'NTLM':
                /*
                 * ntlm_sasl_client.php
                 * Bundled with Permission
                 *
                 * How to telnet in windows:
                 * http://technet.microsoft.com/en-us/library/aa995718%28EXCHG.65%29.aspx
                 * PROTOCOL Docs http://curl.haxx.se/rfc/ntlm.html#ntlmSmtpAuthentication
                 */
                require_once 'extras/ntlm_sasl_client.php';
                $temp = new stdClass;
                $ntlm_client = new ntlm_sasl_client_class;
                //Check that functions are available
                if (!$ntlm_client->initialize($temp)) {
                    $this->setError($temp->error);
                    $this->edebug(
                        'You need to enable some modules in your php.ini file: '
                        . $this->error['error'],
                        self::DEBUG_CLIENT
                    );
                    return false;
                }
                //msg1
                $msg1 = $ntlm_client->typeMsg1($realm, $workstation); //msg1

                if (!$this->sendCommand(
                    'AUTH NTLM',
                    'AUTH NTLM ' . base64_encode($msg1),
                    334
                )
                ) {
                    return false;
                }
                //Though 0 based, there is a white space after the 3 digit number
                //msg2
                $challenge = substr($this->last_reply, 3);
                $challenge = base64_decode($challenge);
                $ntlm_res = $ntlm_client->NTLMResponse(
                    substr($challenge, 24, 8),
                    $password
                );
                //msg3
                $msg3 = $ntlm_client->typeMsg3(
                    $ntlm_res,
                    $username,
                    $realm,
                    $workstation
                );
                // send encoded username
                return $this->sendCommand('Username', base64_encode($msg3), 235);
            case 'CRAM-MD5':
                // Start authentication
                if (!$this->sendCommand('AUTH CRAM-MD5', 'AUTH CRAM-MD5', 334)) {
                    return false;
                }
                // Get the challenge
                $challenge = base64_decode(substr($this->last_reply, 4));

                // Build the response
                $response = $username . ' ' . $this->hmac($challenge, $password);

                // send encoded credentials
                return $this->sendCommand('Username', base64_encode($response), 235);
            default:
                $this->setError("Authentication method \"$authtype\" is not supported");
                return false;
        }
        return true;
    }

    protected function hmac($data, $key)
    {
        if (function_exists('hash_hmac')) {
            return hash_hmac('md5', $data, $key);
        }

        // The following borrowed from
        // http://php.net/manual/en/function.mhash.php#27225

        // RFC 2104 HMAC implementation for php.
        // Creates an md5 HMAC.
        // Eliminates the need to install mhash to compute a HMAC
        // by Lance Rushing

        $bytelen = 64; // byte length for md5
        if (strlen($key) > $bytelen) {
            $key = pack('H*', md5($key));
        }
        $key = str_pad($key, $bytelen, chr(0x00));
        $ipad = str_pad('', $bytelen, chr(0x36));
        $opad = str_pad('', $bytelen, chr(0x5c));
        $k_ipad = $key ^ $ipad;
        $k_opad = $key ^ $opad;

        return md5($k_opad . pack('H*', md5($k_ipad . $data)));
    }

    public function connected()
    {
        if (is_resource($this->smtp_conn)) {
            $sock_status = stream_get_meta_data($this->smtp_conn);
            if ($sock_status['eof']) {
                // The socket is valid but we are not connected
                $this->edebug(
                    'SMTP NOTICE: EOF caught while checking if connected',
                    self::DEBUG_CLIENT
                );
                $this->close();
                return false;
            }
            return true; // everything looks good
        }
        return false;
    }

    public function close()
    {
        $this->setError('');
        $this->server_caps = null;
        $this->helo_rply = null;
        if (is_resource($this->smtp_conn)) {
            // close the connection and cleanup
            fclose($this->smtp_conn);
            $this->smtp_conn = null; //Makes for cleaner serialization
            $this->edebug('Connection: closed', self::DEBUG_CONNECTION);
        }
    }

    public function data($msg_data)
    {
        //This will use the standard timelimit
        if (!$this->sendCommand('DATA', 'DATA', 354)) {
            return false;
        }

        /* The server is ready to accept data!
         * According to rfc821 we should not send more than 1000 characters on a single line (including the CRLF)
         * so we will break the data up into lines by \r and/or \n then if needed we will break each of those into
         * smaller lines to fit within the limit.
         * We will also look for lines that start with a '.' and prepend an additional '.'.
         * NOTE: this does not count towards line-length limit.
         */

        // Normalize line breaks before exploding
        $lines = explode("\n", str_replace(array("\r\n", "\r"), "\n", $msg_data));

        /* To distinguish between a complete RFC822 message and a plain message body, we check if the first field
         * of the first line (':' separated) does not contain a space then it _should_ be a header and we will
         * process all lines before a blank line as headers.
         */

        $field = substr($lines[0], 0, strpos($lines[0], ':'));
        $in_headers = false;
        if (!empty($field) && strpos($field, ' ') === false) {
            $in_headers = true;
        }

        foreach ($lines as $line) {
            $lines_out = array();
            if ($in_headers and $line == '') {
                $in_headers = false;
            }
            //Break this line up into several smaller lines if it's too long
            //Micro-optimisation: isset($str[$len]) is faster than (strlen($str) > $len),
            while (isset($line[self::MAX_LINE_LENGTH])) {
                //Working backwards, try to find a space within the last MAX_LINE_LENGTH chars of the line to break on
                //so as to avoid breaking in the middle of a word
                $pos = strrpos(substr($line, 0, self::MAX_LINE_LENGTH), ' ');
                //Deliberately matches both false and 0
                if (!$pos) {
                    //No nice break found, add a hard break
                    $pos = self::MAX_LINE_LENGTH - 1;
                    $lines_out[] = substr($line, 0, $pos);
                    $line = substr($line, $pos);
                } else {
                    //Break at the found point
                    $lines_out[] = substr($line, 0, $pos);
                    //Move along by the amount we dealt with
                    $line = substr($line, $pos + 1);
                }
                //If processing headers add a LWSP-char to the front of new line RFC822 section 3.1.1
                if ($in_headers) {
                    $line = "\t" . $line;
                }
            }
            $lines_out[] = $line;

            //Send the lines to the server
            foreach ($lines_out as $line_out) {
                //RFC2821 section 4.5.2
                if (!empty($line_out) and $line_out[0] == '.') {
                    $line_out = '.' . $line_out;
                }
                $this->client_send($line_out . self::CRLF);
            }
        }

        //Message data has been sent, complete the command
        //Increase timelimit for end of DATA command
        $savetimelimit = $this->Timelimit;
        $this->Timelimit = $this->Timelimit * 2;
        $result = $this->sendCommand('DATA END', '.', 250);
        //Restore timelimit
        $this->Timelimit = $savetimelimit;
        return $result;
    }

    public function hello($host = '')
    {
        //Try extended hello first (RFC 2821)
        return (boolean)($this->sendHello('EHLO', $host) or $this->sendHello('HELO', $host));
    }

    protected function sendHello($hello, $host)
    {
        $noerror = $this->sendCommand($hello, $hello . ' ' . $host, 250);
        $this->helo_rply = $this->last_reply;
        if ($noerror) {
            $this->parseHelloFields($hello);
        } else {
            $this->server_caps = null;
        }
        return $noerror;
    }

    protected function parseHelloFields($type)
    {
        $this->server_caps = array();
        $lines = explode("\n", $this->helo_rply);

        foreach ($lines as $n => $s) {
            //First 4 chars contain response code followed by - or space
            $s = trim(substr($s, 4));
            if (empty($s)) {
                continue;
            }
            $fields = explode(' ', $s);
            if (!empty($fields)) {
                if (!$n) {
                    $name = $type;
                    $fields = $fields[0];
                } else {
                    $name = array_shift($fields);
                    switch ($name) {
                        case 'SIZE':
                            $fields = ($fields ? $fields[0] : 0);
                            break;
                        case 'AUTH':
                            if (!is_array($fields)) {
                                $fields = array();
                            }
                            break;
                        default:
                            $fields = true;
                    }
                }
                $this->server_caps[$name] = $fields;
            }
        }
    }

    public function mail($from)
    {
        $useVerp = ($this->do_verp ? ' XVERP' : '');
        return $this->sendCommand(
            'MAIL FROM',
            'MAIL FROM:<' . $from . '>' . $useVerp,
            250
        );
    }

    public function quit($close_on_error = true)
    {
        $noerror = $this->sendCommand('QUIT', 'QUIT', 221);
        $err = $this->error; //Save any error
        if ($noerror or $close_on_error) {
            $this->close();
            $this->error = $err; //Restore any error from the quit command
        }
        return $noerror;
    }

    public function recipient($address)
    {
        return $this->sendCommand(
            'RCPT TO',
            'RCPT TO:<' . $address . '>',
            array(250, 251)
        );
    }

    public function reset()
    {
        return $this->sendCommand('RSET', 'RSET', 250);
    }

    protected function sendCommand($command, $commandstring, $expect)
    {
        if (!$this->connected()) {
            $this->setError("Called $command without being connected");
            return false;
        }
        //Reject line breaks in all commands
        if (strpos($commandstring, "\n") !== false or strpos($commandstring, "\r") !== false) {
            $this->setError("Command '$command' contained line breaks");
            return false;
        }
        $this->client_send($commandstring . self::CRLF);

        $this->last_reply = $this->get_lines();
        // Fetch SMTP code and possible error code explanation
        $matches = array();
        if (preg_match("/^([0-9]{3})[ -](?:([0-9]\\.[0-9]\\.[0-9]) )?/", $this->last_reply, $matches)) {
            $code = $matches[1];
            $code_ex = (count($matches) > 2 ? $matches[2] : null);
            // Cut off error code from each response line
            $detail = preg_replace(
                "/{$code}[ -]" .
                ($code_ex ? str_replace('.', '\\.', $code_ex) . ' ' : '') . "/m",
                '',
                $this->last_reply
            );
        } else {
            // Fall back to simple parsing if regex fails
            $code = substr($this->last_reply, 0, 3);
            $code_ex = null;
            $detail = substr($this->last_reply, 4);
        }

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

        if (!in_array($code, (array)$expect)) {
            $this->setError(
                "$command command failed",
                $detail,
                $code,
                $code_ex
            );
            $this->edebug(
                'SMTP ERROR: ' . $this->error['error'] . ': ' . $this->last_reply,
                self::DEBUG_CLIENT
            );
            return false;
        }

        $this->setError('');
        return true;
    }

    public function sendAndMail($from)
    {
        return $this->sendCommand('SAML', "SAML FROM:$from", 250);
    }

    public function verify($name)
    {
        return $this->sendCommand('VRFY', "VRFY $name", array(250, 251));
    }

    public function noop()
    {
        return $this->sendCommand('NOOP', 'NOOP', 250);
    }

    public function turn()
    {
        $this->setError('The SMTP TURN command is not implemented');
        $this->edebug('SMTP NOTICE: ' . $this->error['error'], self::DEBUG_CLIENT);
        return false;
    }

    public function client_send($data)
    {
        $this->edebug("CLIENT -> SERVER: $data", self::DEBUG_CLIENT);
        set_error_handler(array($this, 'errorHandler'));
        $result = fwrite($this->smtp_conn, $data);
        restore_error_handler();
        return $result;
    }

    public function getError()
    {
        return $this->error;
    }

    public function getServerExtList()
    {
        return $this->server_caps;
    }

    public function getServerExt($name)
    {
        if (!$this->server_caps) {
            $this->setError('No HELO/EHLO was sent');
            return null;
        }

        // the tight logic knot ;)
        if (!array_key_exists($name, $this->server_caps)) {
            if ($name == 'HELO') {
                return $this->server_caps['EHLO'];
            }
            if ($name == 'EHLO' || array_key_exists('EHLO', $this->server_caps)) {
                return false;
            }
            $this->setError('HELO handshake was used. Client knows nothing about server extensions');
            return null;
        }

        return $this->server_caps[$name];
    }

    public function getLastReply()
    {
        return $this->last_reply;
    }

    protected function get_lines()
    {
        // If the connection is bad, give up straight away
        if (!is_resource($this->smtp_conn)) {
            return '';
        }
        $data = '';
        $endtime = 0;
        stream_set_timeout($this->smtp_conn, $this->Timeout);
        if ($this->Timelimit > 0) {
            $endtime = time() + $this->Timelimit;
        }
        while (is_resource($this->smtp_conn) && !feof($this->smtp_conn)) {
            $str = @fgets($this->smtp_conn, 515);
            $this->edebug("SMTP -> get_lines(): \$data is \"$data\"", self::DEBUG_LOWLEVEL);
            $this->edebug("SMTP -> get_lines(): \$str is  \"$str\"", self::DEBUG_LOWLEVEL);
            $data .= $str;
            // If response is only 3 chars (not valid, but RFC5321 S4.2 says it must be handled),
            // or 4th character is a space, we are done reading, break the loop,
            // string array access is a micro-optimisation over strlen
            if (!isset($str[3]) or (isset($str[3]) and $str[3] == ' ')) {
                break;
            }
            // Timed-out? Log and break
            $info = stream_get_meta_data($this->smtp_conn);
            if ($info['timed_out']) {
                $this->edebug(
                    'SMTP -> get_lines(): timed-out (' . $this->Timeout . ' sec)',
                    self::DEBUG_LOWLEVEL
                );
                break;
            }
            // Now check if reads took too long
            if ($endtime and time() > $endtime) {
                $this->edebug(
                    'SMTP -> get_lines(): timelimit reached (' .
                    $this->Timelimit . ' sec)',
                    self::DEBUG_LOWLEVEL
                );
                break;
            }
        }
        return $data;
    }

    public function setVerp($enabled = false)
    {
        $this->do_verp = $enabled;
    }

    public function getVerp()
    {
        return $this->do_verp;
    }

    protected function setError($message, $detail = '', $smtp_code = '', $smtp_code_ex = '')
    {
        $this->error = array(
            'error' => $message,
            'detail' => $detail,
            'smtp_code' => $smtp_code,
            'smtp_code_ex' => $smtp_code_ex
        );
    }

    public function setDebugOutput($method = 'echo')
    {
        $this->Debugoutput = $method;
    }

    public function getDebugOutput()
    {
        return $this->Debugoutput;
    }

    public function setDebugLevel($level = 0)
    {
        $this->do_debug = $level;
    }

    public function getDebugLevel()
    {
        return $this->do_debug;
    }

    public function setTimeout($timeout = 0)
    {
        $this->Timeout = $timeout;
    }

    public function getTimeout()
    {
        return $this->Timeout;
    }

    protected function errorHandler($errno, $errmsg, $errfile = '', $errline = 0)
    {
        $notice = 'Connection failed.';
        $this->setError(
            $notice,
            $errno,
            $errmsg
        );
        $this->edebug(
            $notice . ' Error #' . $errno . ': ' . $errmsg . " [$errfile line $errline]",
            self::DEBUG_CONNECTION
        );
    }

    public function getLastTransactionID()
    {
        $reply = $this->getLastReply();

        if (empty($reply)) {
            return null;
        }

        foreach ($this->smtp_transaction_id_patterns as $smtp_transaction_id_pattern) {
            if (preg_match($smtp_transaction_id_pattern, $reply, $matches)) {
                return $matches[1];
            }
        }

        return false;
    }
}