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<?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 - 2020 Marcus Bointon * @copyright 2010 - 2012 Jim Jagielski * @copyright 2004 - 2009 Andy Prevost * @license https://www.gnu.org/licenses/old-licenses/lgpl-2.1.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 = '7.0.0'; /* * 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 SMTPs port to use if one is not specified. * * @var int / const DEFAULT_SECURE_PORT = 465; /* * The maximum line length allowed by RFC 5321 section 4.5.3.1.6, * excluding a trailing CRLF break. * * @see https://www.rfc-editor.org/rfc/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://www.rfc-editor.org/rfc/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 https://en.wikipedia.org/wiki/Variable_envelope_return_path * @see https://www.postfix.org/VERP_README.html Info on VERP * * @var bool / public $do_verp = false; /* * Whether to use SMTPUTF8. * * @see https://www.rfc-editor.org/rfc/rfc6531 * * @var bool / public $do_smtputf8 = 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 https://www.rfc-editor.org/rfc/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})/', 'Haraka' => '/[\d]{3} Message Queued \((.)\)/', 'ZoneMTA' => '/[\d]{3} Message queued as (.)/', 'Mailjet' => '/[\d]{3} OK queued as (.)/', 'Gsmtp' => '/[\d]{3} 2\.0\.0 OK (.) - gsmtp/', ]; /** * Allowed SMTP XCLIENT attributes. * Must be allowed by the SMTP server. EHLO response is not checked. * * @see https://www.postfix.org/XCLIENT_README.html * * @var array / public static $xclient_allowed_attributes = [ 'NAME', 'ADDR', 'PORT', 'PROTO', 'HELO', 'LOGIN', 'DESTADDR', 'DESTPORT' ]; /* * 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) { //Remove trailing line breaks potentially added by calls to SMTP::client_send() $this->Debugoutput->debug(rtrim($str, "\r\n")); 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 /* @noinspection ForgottenDebugOutputInspection / 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 = []) { //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 ); $this->smtp_conn = $this->getSMTPConnection($host, $port, $timeout, $options); if ($this->smtp_conn === false) { //Error info already set inside `getSMTPConnection()` return false; } $this->edebug('Connection: opened', self::DEBUG_CONNECTION); //Get any announcement $this->last_reply = $this->get_lines(); $this->edebug('SERVER -> CLIENT: ' . $this->last_reply, self::DEBUG_SERVER); $responseCode = (int)substr($this->last_reply, 0, 3); if ($responseCode === 220) { return true; } //Anything other than a 220 response means something went wrong //RFC 5321 says the server will wait for us to send a QUIT in response to a 554 error //https://www.rfc-editor.org/rfc/rfc5321#section-3.1 if ($responseCode === 554) { $this->quit(); } //This will handle 421 responses which may not wait for a QUIT (e.g. if the server is being shut down) $this->edebug('Connection: closing due to error', self::DEBUG_CONNECTION); $this->close(); return false; } /* * Create connection to the 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 $options An array of options for stream_context_create() * * @return false\|resource / protected function getSMTPConnection($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'); } $errno = 0; $errstr = ''; if ($streamok) { $socket_context = stream_context_create($options); set_error_handler(function () { call_user_func_array([$this, 'errorHandler'], func_get_args()); }); $connection = stream_socket_client( $host . ':' . $port, $errno, $errstr, $timeout, STREAM_CLIENT_CONNECT, $socket_context ); } else { //Fall back to fsockopen which should work in more places, but is missing some features $this->edebug( 'Connection: stream_socket_client not available, falling back to fsockopen', self::DEBUG_CONNECTION ); set_error_handler(function () { call_user_func_array([$this, 'errorHandler'], func_get_args()); }); $connection = fsockopen( $host, $port, $errno, $errstr, $timeout ); } restore_error_handler(); //Verify we connected properly if (!is_resource($connection)) { $this->setError( 'Failed to connect to server', '', (string) $errno, $errstr ); $this->edebug( 'SMTP ERROR: ' . $this->error['error'] . ": $errstr ($errno)", self::DEBUG_CLIENT ); return false; } //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, or if set_time_limit is disabled if (0 !== $max && $timeout > $max && strpos(ini_get('disable_functions'), 'set_time_limit') === false) { @set_time_limit($timeout); } stream_set_timeout($connection, $timeout, 0); } return $connection; } /* * Initiate a TLS (encrypted) session. * * @return bool / public function startTLS() { if (!$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; $crypto_method \|= STREAM_CRYPTO_METHOD_TLSv1_1_CLIENT; } //Begin encrypted connection set_error_handler(function () { call_user_func_array([$this, 'errorHandler'], func_get_args()); }); $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 OAuthTokenProvider $OAuth An optional OAuthTokenProvider 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 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; } $this->edebug('Auth method requested: ' . ($authtype ?: 'UNSPECIFIED'), self::DEBUG_LOWLEVEL); $this->edebug( 'Auth methods available on the server: ' . implode(',', $this->server_caps['AUTH']), self::DEBUG_LOWLEVEL ); //If we have requested a specific auth type, check the server supports it before trying others if (null !== $authtype && !in_array($authtype, $this->server_caps['AUTH'], true)) { $this->edebug('Requested auth method not available: ' . $authtype, self::DEBUG_LOWLEVEL); $authtype = null; } if (empty($authtype)) { //If no auth mechanism is specified, attempt to use these, in this order //Try CRAM-MD5 first as it's more secure than the others foreach (['CRAM-MD5', 'LOGIN', 'PLAIN', 'XOAUTH2'] as $method) { if (in_array($method, $this->server_caps['AUTH'], true)) { $authtype = $method; break; } } if (empty($authtype)) { $this->setError('No supported authentication methods found'); return false; } $this->edebug('Auth method selected: ' . $authtype, self::DEBUG_LOWLEVEL); } if (!in_array($authtype, $this->server_caps['AUTH'], true)) { $this->setError("The requested authentication method \"$authtype\" is not supported by the server"); return false; } } elseif (empty($authtype)) { $authtype = 'LOGIN'; } switch ($authtype) { case 'PLAIN': //Start authentication if (!$this->sendCommand('AUTH', 'AUTH PLAIN', 334)) { return false; } //Send encoded username and password if ( //Format from https://www.rfc-editor.org/rfc/rfc4616#section-2 //We skip the first field (it's forgery), so the string starts with a null byte !$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 '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); case 'XOAUTH2': //The OAuth instance must be set up prior to requesting auth. if (null === $OAuth) { return false; } $oauth = $OAuth->getOauth64(); / * An SMTP command line can have a maximum length of 512 bytes, including the command name, * so the base64-encoded OAUTH token has a maximum length of: * 512 - 13 (AUTH XOAUTH2) - 2 (CRLF) = 497 bytes * If the token is longer than that, the command and the token must be sent separately as described in * https://www.rfc-editor.org/rfc/rfc4954#section-4 / if ($oauth === '') { //Sending an empty auth token is legitimate, but it must be encoded as '=' //to indicate it's not a 2-part command if (!$this->sendCommand('AUTH', 'AUTH XOAUTH2 =', 235)) { return false; } } elseif (strlen($oauth) <= 497) { //Authenticate using a token in the initial-response part if (!$this->sendCommand('AUTH', 'AUTH XOAUTH2 ' . $oauth, 235)) { return false; } } else { //The token is too long, so we need to send it in two parts. //Send the auth command without a token and expect a 334 if (!$this->sendCommand('AUTH', 'AUTH XOAUTH2', 334)) { return false; } //Send the token if (!$this->sendCommand('OAuth TOKEN', $oauth, [235, 334])) { return false; } //If the server answers with 334, send an empty line and wait for a 235 if ( substr($this->last_reply, 0, 3) === '334' && $this->sendCommand('AUTH End', '', 235) ) { return false; } } break; default: $this->setError("Authentication method \"$authtype\" is not supported"); return false; } return true; } /* * Calculate an MD5 HMAC hash. * Works like hash_hmac('md5', $data, $key) * in case that function is not available. * * @param string $data The data to hash * @param string $key The key to hash with * * @return string / protected function hmac($data, $key) { if (function_exists('hash_hmac')) { return hash_hmac('md5', $data, $key); } //The following borrowed from //https://www.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 . $data))); } /* * Check connection state. * * @return bool True if connected / public function connected() { if (is_resource($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; } /* * Close the socket and clean up the state of the class. * Don't use this function without first trying to use QUIT. * * @see quit() / public function close() { $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); } } /* * Send an SMTP DATA command. * Issues a data command and sends the msg_data to the server, * finalizing the mail transaction. $msg_data is the message * that is to be sent with the headers. Each header needs to be * on a single line followed by a <CRLF> with the message headers * and the message body being separated by an additional <CRLF>. * Implements RFC 821: DATA <CRLF>. * * @param string $msg_data Message data to send * * @return bool / public function data($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 LE) * 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(["\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) { $lines_out = []; if ($in_headers && $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 $line_out) { //Dot-stuffing as per RFC5321 section 4.5.2 //https://www.rfc-editor.org/rfc/rfc5321#section-4.5.2 if (!empty($line_out) && $line_out[0] === '.') { $line_out = '.' . $line_out; } $this->client_send($line_out . static::LE, 'DATA'); } } //Message data has been sent, complete the command //Increase timelimit for end of DATA command $savetimelimit = $this->Timelimit; $this->Timelimit = 2; $result = $this->sendCommand('DATA END', '.', 250); $this->recordLastTransactionID(); //Restore timelimit $this->Timelimit = $savetimelimit; return $result; } /** * Send an SMTP HELO or EHLO command. * Used to identify the sending server to the receiving server. * This makes sure that client and server are in a known state. * Implements RFC 821: HELO <SP> <domain> <CRLF> * and RFC 2821 EHLO. * * @param string $host The host name or IP to connect to * * @return bool / public function hello($host = '') { //Try extended hello first (RFC 2821) if ($this->sendHello('EHLO', $host)) { return true; } //Some servers shut down the SMTP service here (RFC 5321) if (substr($this->helo_rply, 0, 3) == '421') { return false; } return $this->sendHello('HELO', $host); } /* * Send an SMTP HELO or EHLO command. * Low-level implementation used by hello(). * * @param string $hello The HELO string * @param string $host The hostname to say we are * * @return bool * * @see hello() / protected function sendHello($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; } /* * Parse a reply to HELO/EHLO command to discover server extensions. * In case of HELO, the only parameter that can be discovered is a server name. * * @param string $type `HELO` or `EHLO` / protected function parseHelloFields($type) { $this->server_caps = []; $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 = []; } break; default: $fields = true; } } $this->server_caps[$name] = $fields; } } } /* * Send an SMTP MAIL command. * Starts a mail transaction from the email address specified in * $from. Returns true if successful or false otherwise. If True * the mail transaction is started and then one or more recipient * commands may be called followed by a data command. * Implements RFC 821: MAIL <SP> FROM:<reverse-path> <CRLF> and * two extensions, namely XVERP and SMTPUTF8. * * The server's EHLO response is not checked. If use of either * extensions is enabled even though the server does not support * that, mail submission will fail. * * XVERP is documented at https://www.postfix.org/VERP_README.html * and SMTPUTF8 is specified in RFC 6531. * * @param string $from Source address of this message * * @return bool / public function mail($from) { $useVerp = ($this->do_verp ? ' XVERP' : ''); $useSmtputf8 = ($this->do_smtputf8 ? ' SMTPUTF8' : ''); return $this->sendCommand( 'MAIL FROM', 'MAIL FROM:<' . $from . '>' . $useSmtputf8 . $useVerp, 250 ); } /* * Send an SMTP QUIT command. * Closes the socket if there is no error or the $close_on_error argument is true. * Implements from RFC 821: QUIT <CRLF>. * * @param bool $close_on_error Should the connection close if an error occurs? * * @return bool / public function quit($close_on_error = true) { $noerror = $this->sendCommand('QUIT', 'QUIT', 221); $err = $this->error; //Save any error if ($noerror \|\| $close_on_error) { $this->close(); $this->error = $err; //Restore any error from the quit command } return $noerror; } /* * Send an SMTP RCPT command. * Sets the TO argument to $toaddr. * Returns true if the recipient was accepted false if it was rejected. * Implements from RFC 821: RCPT <SP> TO:<forward-path> <CRLF>. * * @param string $address The address the message is being sent to * @param string $dsn Comma separated list of DSN notifications. NEVER, SUCCESS, FAILURE * or DELAY. If you specify NEVER all other notifications are ignored. * * @return bool / public function recipient($address, $dsn = '') { if (empty($dsn)) { $rcpt = 'RCPT TO:<' . $address . '>'; } else { $dsn = strtoupper($dsn); $notify = []; if (strpos($dsn, 'NEVER') !== false) { $notify[] = 'NEVER'; } else { foreach (['SUCCESS', 'FAILURE', 'DELAY'] as $value) { if (strpos($dsn, $value) !== false) { $notify[] = $value; } } } $rcpt = 'RCPT TO:<' . $address . '> NOTIFY=' . implode(',', $notify); } return $this->sendCommand( 'RCPT TO', $rcpt, [250, 251] ); } /* * Send SMTP XCLIENT command to server and check its return code. * * @return bool True on success / public function xclient(array $vars) { $xclient_options = ""; foreach ($vars as $key => $value) { if (in_array($key, SMTP::$xclient_allowed_attributes)) { $xclient_options .= " {$key}={$value}"; } } if (!$xclient_options) { return true; } return $this->sendCommand('XCLIENT', 'XCLIENT' . $xclient_options, 250); } /* * Send an SMTP RSET command. * Abort any transaction that is currently in progress. * Implements RFC 821: RSET <CRLF>. * * @return bool True on success / public function reset() { return $this->sendCommand('RSET', 'RSET', 250); } /* * Send a command to an SMTP server and check its return code. * * @param string $command The command name - not sent to the server * @param string $commandstring The actual command to send * @param int\|array $expect One or more expected integer success codes * * @return bool True on success / protected function sendCommand($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) \|\| (strpos($commandstring, "\r") !== false)) { $this->setError("Command '$command' contained line breaks"); return false; } $this->client_send($commandstring . static::LE, $command); $this->last_reply = $this->get_lines(); //Fetch SMTP code and possible error code explanation $matches = []; if (preg_match('/^([\d]{3})[ -](?:([\d]\\.[\d]\\.[\d]{1,2}) )?/', $this->last_reply, $matches)) { $code = (int) $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 $code = (int) substr($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, true)) { $this->setError( "$command command failed", $detail, $code, $code_ex ); $this->edebug( 'SMTP ERROR: ' . $this->error['error'] . ': ' . $this->last_reply, self::DEBUG_CLIENT ); return false; } //Don't clear the error store when using keepalive if ($command !== 'RSET') { $this->setError(''); } return true; } /* * Send an SMTP SAML command. * Starts a mail transaction from the email address specified in $from. * Returns true if successful or false otherwise. If True * the mail transaction is started and then one or more recipient * commands may be called followed by a data command. This command * will send the message to the users terminal if they are logged * in and send them an email. * Implements RFC 821: SAML <SP> FROM:<reverse-path> <CRLF>. * * @param string $from The address the message is from * * @return bool / public function sendAndMail($from) { return $this->sendCommand('SAML', "SAML FROM:$from", 250); } /* * Send an SMTP VRFY command. * * @param string $name The name to verify * * @return bool / public function verify($name) { return $this->sendCommand('VRFY', "VRFY $name", [250, 251]); } /* * Send an SMTP NOOP command. * Used to keep keep-alives alive, doesn't actually do anything. * * @return bool / public function noop() { return $this->sendCommand('NOOP', 'NOOP', 250); } /* * Send an SMTP TURN command. * This is an optional command for SMTP that this class does not support. * This method is here to make the RFC821 Definition complete for this class * and _may_ be implemented in future. * Implements from RFC 821: TURN <CRLF>. * * @return bool / public function turn() { $this->setError('The SMTP TURN command is not implemented'); $this->edebug('SMTP NOTICE: ' . $this->error['error'], self::DEBUG_CLIENT); return false; } /* * Send raw data to the server. * * @param string $data The data to send * @param string $command Optionally, the command this is part of, used only for controlling debug output * * @return int\|bool The number of bytes sent to the server or false on error / public function client_send($data, $command = '') { //If SMTP transcripts are left enabled, or debug output is posted online //it can leak credentials, so hide credentials in all but lowest level if ( self::DEBUG_LOWLEVEL > $this->do_debug && in_array($command, ['User & Password', 'Username', 'Password'], true) ) { $this->edebug('CLIENT -> SERVER: [credentials hidden]', self::DEBUG_CLIENT); } else { $this->edebug('CLIENT -> SERVER: ' . $data, self::DEBUG_CLIENT); } set_error_handler(function () { call_user_func_array([$this, 'errorHandler'], func_get_args()); }); $result = fwrite($this->smtp_conn, $data); restore_error_handler(); return $result; } /* * Get the latest error. * * @return array / public function getError() { return $this->error; } /* * Get SMTP extensions available on the server. * * @return array\|null / public function getServerExtList() { return $this->server_caps; } /* * Get metadata about the SMTP server from its HELO/EHLO response. * The method works in three ways, dependent on argument value and current state: * 1. HELO/EHLO has not been sent - returns null and populates $this->error. * 2. HELO has been sent - * $name == 'HELO': returns server name * $name == 'EHLO': returns boolean false * $name == any other string: returns null and populates $this->error * 3. EHLO has been sent - * $name == 'HELO'\|'EHLO': returns the server name * $name == any other string: if extension $name exists, returns True * or its options (e.g. AUTH mechanisms supported). Otherwise returns False. * * @param string $name Name of SMTP extension or 'HELO'\|'EHLO' * * @return string\|bool\|null / public function getServerExt($name) { if (!$this->server_caps) { $this->setError('No HELO/EHLO was sent'); return null; } if (!array_key_exists($name, $this->server_caps)) { if ('HELO' === $name) { return $this->server_caps['EHLO']; } if ('EHLO' === $name \|\| array_key_exists('EHLO', $this->server_caps)) { return false; } $this->setError('HELO handshake was used; No information about server extensions available'); return null; } return $this->server_caps[$name]; } /* * Get the last reply from the server. * * @return string / public function getLastReply() { return $this->last_reply; } /* * Read the SMTP server's response. * Either before eof or socket timeout occurs on the operation. * With SMTP we can tell if we have more lines to read if the * 4th character is '-' symbol. If it is a space then we don't * need to read anything else. * * @return string / protected function get_lines() { //If the connection is bad, give up straight away if (!is_resource($this->smtp_conn)) { return ''; } $data = ''; $endtime = 0; stream_set_timeout($this->smtp_conn, $this->Timeout); if ($this->Timelimit > 0) { $endtime = time() + $this->Timelimit; } $selR = [$this->smtp_conn]; $selW = null; while (is_resource($this->smtp_conn) && !feof($this->smtp_conn)) { //Must pass vars in here as params are by reference //solution for signals inspired by https://github.com/symfony/symfony/pull/6540 set_error_handler(function () { call_user_func_array([$this, 'errorHandler'], func_get_args()); }); $n = stream_select($selR, $selW, $selW, $this->Timelimit); restore_error_handler(); if ($n === false) { $message = $this->getError()['detail']; $this->edebug( 'SMTP -> get_lines(): select failed (' . $message . ')', self::DEBUG_LOWLEVEL ); //stream_select returns false when the `select` system call is interrupted //by an incoming signal, try the select again if ( stripos($message, 'interrupted system call') !== false \|\| ( // on applications with a different locale than english, the message above is not found because // it's translated. So we also check for the SOCKET_EINTR constant which is defined under // Windows and UNIX-like platforms (if available on the platform). defined('SOCKET_EINTR') && stripos($message, 'stream_select(): Unable to select [' . SOCKET_EINTR . ']') !== false ) ) { $this->edebug( 'SMTP -> get_lines(): retrying stream_select', self::DEBUG_LOWLEVEL ); $this->setError(''); continue; } break; } if (!$n) { $this->edebug( 'SMTP -> get_lines(): select timed-out in (' . $this->Timelimit . ' sec)', self::DEBUG_LOWLEVEL ); break; } //Deliberate noise suppression - errors are handled afterwards $str = @fgets($this->smtp_conn, self::MAX_REPLY_LENGTH); $this->edebug('SMTP INBOUND: "' . trim($str) . '"', self::DEBUG_LOWLEVEL); $data .= $str; //If response is only 3 chars (not valid, but RFC5321 S4.2 says it must be handled), //or 4th character is a space or a line break char, we are done reading, break the loop. //String array access is a significant micro-optimisation over strlen if (!isset($str[3]) \|\| $str[3] === ' ' \|\| $str[3] === "\r" \|\| $str[3] === "\n") { break; } //Timed-out? Log and break $info = stream_get_meta_data($this->smtp_conn); if ($info['timed_out']) { $this->edebug( 'SMTP -> get_lines(): stream timed-out (' . $this->Timeout . ' sec)', self::DEBUG_LOWLEVEL ); break; } //Now check if reads took too long if ($endtime && time() > $endtime) { $this->edebug( 'SMTP -> get_lines(): timelimit reached (' . $this->Timelimit . ' sec)', self::DEBUG_LOWLEVEL ); break; } } return $data; } /* * Enable or disable VERP address generation. * * @param bool $enabled / public function setVerp($enabled = false) { $this->do_verp = $enabled; } /* * Get VERP address generation mode. * * @return bool / public function getVerp() { return $this->do_verp; } /* * Enable or disable use of SMTPUTF8. * * @param bool $enabled / public function setSMTPUTF8($enabled = false) { $this->do_smtputf8 = $enabled; } /* * Get SMTPUTF8 use. * * @return bool / public function getSMTPUTF8() { return $this->do_smtputf8; } /* * Set error messages and codes. * * @param string $message The error message * @param string $detail Further detail on the error * @param string $smtp_code An associated SMTP error code * @param string $smtp_code_ex Extended SMTP code / protected function setError($message, $detail = '', $smtp_code = '', $smtp_code_ex = '') { $this->error = [ 'error' => $message, 'detail' => $detail, 'smtp_code' => $smtp_code, 'smtp_code_ex' => $smtp_code_ex, ]; } /* * Set debug output method. * * @param string\|callable $method The name of the mechanism to use for debugging output, or a callable to handle it / public function setDebugOutput($method = 'echo') { $this->Debugoutput = $method; } /* * Get debug output method. * * @return string / public function getDebugOutput() { return $this->Debugoutput; } /* * Set debug output level. * * @param int $level / public function setDebugLevel($level = 0) { $this->do_debug = $level; } /* * Get debug output level. * * @return int / public function getDebugLevel() { return $this->do_debug; } /* * Set SMTP timeout. * * @param int $timeout The timeout duration in seconds / public function setTimeout($timeout = 0) { $this->Timeout = $timeout; } /* * Get SMTP timeout. * * @return int / public function getTimeout() { return $this->Timeout; } /* * Reports an error number and string. * * @param int $errno The error number returned by PHP * @param string $errmsg The error message returned by PHP * @param string $errfile The file the error occurred in * @param int $errline The line number the error occurred on / protected function errorHandler($errno, $errmsg, $errfile = '', $errline = 0) { $notice = 'Connection failed.'; $this->setError( $notice, $errmsg, (string) $errno ); $this->edebug( "$notice Error #$errno: $errmsg [$errfile line $errline]", self::DEBUG_CONNECTION ); } /* * Extract and return the ID of the last SMTP transaction based on * a list of patterns provided in SMTP::$smtp_transaction_id_patterns. * Relies on the host providing the ID in response to a DATA command. * If no reply has been received yet, it will return null. * If no pattern was matched, it will return false. * * @return bool\|string\|null / protected function recordLastTransactionID() { $reply = $this->getLastReply(); if (empty($reply)) { $this->last_smtp_transaction_id = null; } else { $this->last_smtp_transaction_id = false; foreach ($this->smtp_transaction_id_patterns as $smtp_transaction_id_pattern) { $matches = []; if (preg_match($smtp_transaction_id_pattern, $reply, $matches)) { $this->last_smtp_transaction_id = trim($matches[1]); break; } } } return $this->last_smtp_transaction_id; } /* * Get the queue/transaction ID of the last SMTP transaction * If no reply has been received yet, it will return null. * If no pattern was matched, it will return false. * * @return bool\|string\|null * * @see recordLastTransactionID() */ public function getLastTransactionID() { return $this->last_smtp_transaction_id; } } Back

Edit File : SMTP.php | Size : 51.25 KB

<?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 - 2020 Marcus Bointon
 * @copyright 2010 - 2012 Jim Jagielski
 * @copyright 2004 - 2009 Andy Prevost
 * @license   https://www.gnu.org/licenses/old-licenses/lgpl-2.1.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 = '7.0.0';

/**
     * 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 SMTPs port to use if one is not specified.
     *
     * @var int
     */
    const DEFAULT_SECURE_PORT = 465;

/**
     * The maximum line length allowed by RFC 5321 section 4.5.3.1.6,
     * *excluding* a trailing CRLF break.
     *
     * @see https://www.rfc-editor.org/rfc/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://www.rfc-editor.org/rfc/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 https://en.wikipedia.org/wiki/Variable_envelope_return_path
     * @see https://www.postfix.org/VERP_README.html Info on VERP
     *
     * @var bool
     */
    public $do_verp = false;

/**
     * Whether to use SMTPUTF8.
     *
     * @see https://www.rfc-editor.org/rfc/rfc6531
     *
     * @var bool
     */
    public $do_smtputf8 = 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 https://www.rfc-editor.org/rfc/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})/',
        'Haraka' => '/[\d]{3} Message Queued $(.*)$/',
        'ZoneMTA' => '/[\d]{3} Message queued as (.*)/',
        'Mailjet' => '/[\d]{3} OK queued as (.*)/',
        'Gsmtp' => '/[\d]{3} 2\.0\.0 OK (.*) - gsmtp/',
    ];

/**
     * Allowed SMTP XCLIENT attributes.
     * Must be allowed by the SMTP server. EHLO response is not checked.
     *
     * @see https://www.postfix.org/XCLIENT_README.html
     *
     * @var array
     */
    public static $xclient_allowed_attributes = [
        'NAME', 'ADDR', 'PORT', 'PROTO', 'HELO', 'LOGIN', 'DESTADDR', 'DESTPORT'
    ];

/**
     * 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) {
            //Remove trailing line breaks potentially added by calls to SMTP::client_send()
            $this->Debugoutput->debug(rtrim($str, "\r\n"));

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 ($this->Debugoutput) {
            case 'error_log':
                //Don't output, just log
                /** @noinspection ForgottenDebugOutputInspection */
                error_log($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 = [])
    {
        //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
        );

$this->smtp_conn = $this->getSMTPConnection($host, $port, $timeout, $options);

if ($this->smtp_conn === false) {
            //Error info already set inside `getSMTPConnection()`
            return false;
        }

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

//Get any announcement
        $this->last_reply = $this->get_lines();
        $this->edebug('SERVER -> CLIENT: ' . $this->last_reply, self::DEBUG_SERVER);
        $responseCode = (int)substr($this->last_reply, 0, 3);
        if ($responseCode === 220) {
            return true;
        }
        //Anything other than a 220 response means something went wrong
        //RFC 5321 says the server will wait for us to send a QUIT in response to a 554 error
        //https://www.rfc-editor.org/rfc/rfc5321#section-3.1
        if ($responseCode === 554) {
            $this->quit();
        }
        //This will handle 421 responses which may not wait for a QUIT (e.g. if the server is being shut down)
        $this->edebug('Connection: closing due to error', self::DEBUG_CONNECTION);
        $this->close();
        return false;
    }

/**
     * Create connection to the 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  $options An array of options for stream_context_create()
     *
     * @return false|resource
     */
    protected function getSMTPConnection($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');
        }

$errno = 0;
        $errstr = '';
        if ($streamok) {
            $socket_context = stream_context_create($options);
            set_error_handler(function () {
                call_user_func_array([$this, 'errorHandler'], func_get_args());
            });
            $connection = stream_socket_client(
                $host . ':' . $port,
                $errno,
                $errstr,
                $timeout,
                STREAM_CLIENT_CONNECT,
                $socket_context
            );
        } else {
            //Fall back to fsockopen which should work in more places, but is missing some features
            $this->edebug(
                'Connection: stream_socket_client not available, falling back to fsockopen',
                self::DEBUG_CONNECTION
            );
            set_error_handler(function () {
                call_user_func_array([$this, 'errorHandler'], func_get_args());
            });
            $connection = fsockopen(
                $host,
                $port,
                $errno,
                $errstr,
                $timeout
            );
        }
        restore_error_handler();

//Verify we connected properly
        if (!is_resource($connection)) {
            $this->setError(
                'Failed to connect to server',
                '',
                (string) $errno,
                $errstr
            );
            $this->edebug(
                'SMTP ERROR: ' . $this->error['error']
                . ": $errstr ($errno)",
                self::DEBUG_CLIENT
            );

return false;
        }

//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, or if set_time_limit is disabled
            if (0 !== $max && $timeout > $max && strpos(ini_get('disable_functions'), 'set_time_limit') === false) {
                @set_time_limit($timeout);
            }
            stream_set_timeout($connection, $timeout, 0);
        }

return $connection;
    }

/**
     * 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(function () {
                call_user_func_array([$this, 'errorHandler'], func_get_args());
            });
        $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 OAuthTokenProvider $OAuth An optional OAuthTokenProvider 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
            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;
            }

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

//If we have requested a specific auth type, check the server supports it before trying others
            if (null !== $authtype && !in_array($authtype, $this->server_caps['AUTH'], true)) {
                $this->edebug('Requested auth method not available: ' . $authtype, self::DEBUG_LOWLEVEL);
                $authtype = null;
            }

if (empty($authtype)) {
                //If no auth mechanism is specified, attempt to use these, in this order
                //Try CRAM-MD5 first as it's more secure than the others
                foreach (['CRAM-MD5', 'LOGIN', 'PLAIN', 'XOAUTH2'] as $method) {
                    if (in_array($method, $this->server_caps['AUTH'], true)) {
                        $authtype = $method;
                        break;
                    }
                }
                if (empty($authtype)) {
                    $this->setError('No supported authentication methods found');

return false;
                }
                $this->edebug('Auth method selected: ' . $authtype, self::DEBUG_LOWLEVEL);
            }

if (!in_array($authtype, $this->server_caps['AUTH'], true)) {
                $this->setError("The requested authentication method \"$authtype\" is not supported by the server");

return false;
            }
        } elseif (empty($authtype)) {
            $authtype = 'LOGIN';
        }
        switch ($authtype) {
            case 'PLAIN':
                //Start authentication
                if (!$this->sendCommand('AUTH', 'AUTH PLAIN', 334)) {
                    return false;
                }
                //Send encoded username and password
                if (
                    //Format from https://www.rfc-editor.org/rfc/rfc4616#section-2
                    //We skip the first field (it's forgery), so the string starts with a null byte
                    !$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 '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);
            case 'XOAUTH2':
                //The OAuth instance must be set up prior to requesting auth.
                if (null === $OAuth) {
                    return false;
                }
                $oauth = $OAuth->getOauth64();
                /*
                 * An SMTP command line can have a maximum length of 512 bytes, including the command name,
                 * so the base64-encoded OAUTH token has a maximum length of:
                 * 512 - 13 (AUTH XOAUTH2) - 2 (CRLF) = 497 bytes
                 * If the token is longer than that, the command and the token must be sent separately as described in
                 * https://www.rfc-editor.org/rfc/rfc4954#section-4
                 */
                if ($oauth === '') {
                    //Sending an empty auth token is legitimate, but it must be encoded as '='
                    //to indicate it's not a 2-part command
                    if (!$this->sendCommand('AUTH', 'AUTH XOAUTH2 =', 235)) {
                        return false;
                    }
                } elseif (strlen($oauth) <= 497) {
                    //Authenticate using a token in the initial-response part
                    if (!$this->sendCommand('AUTH', 'AUTH XOAUTH2 ' . $oauth, 235)) {
                        return false;
                    }
                } else {
                    //The token is too long, so we need to send it in two parts.
                    //Send the auth command without a token and expect a 334
                    if (!$this->sendCommand('AUTH', 'AUTH XOAUTH2', 334)) {
                        return false;
                    }
                    //Send the token
                    if (!$this->sendCommand('OAuth TOKEN', $oauth, [235, 334])) {
                        return false;
                    }
                    //If the server answers with 334, send an empty line and wait for a 235
                    if (
                        substr($this->last_reply, 0, 3) === '334'
                        && $this->sendCommand('AUTH End', '', 235)
                    ) {
                        return false;
                    }
                }
                break;
            default:
                $this->setError("Authentication method \"$authtype\" is not supported");

return false;
        }

return true;
    }

/**
     * Calculate an MD5 HMAC hash.
     * Works like hash_hmac('md5', $data, $key)
     * in case that function is not available.
     *
     * @param string $data The data to hash
     * @param string $key  The key to hash with
     *
     * @return string
     */
    protected function hmac($data, $key)
    {
        if (function_exists('hash_hmac')) {
            return hash_hmac('md5', $data, $key);
        }

//The following borrowed from
        //https://www.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)));
    }

/**
     * Check connection state.
     *
     * @return bool True if connected
     */
    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;
    }

/**
     * Close the socket and clean up the state of the class.
     * Don't use this function without first trying to use QUIT.
     *
     * @see quit()
     */
    public function close()
    {
        $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);
        }
    }

/**
     * Send an SMTP DATA command.
     * Issues a data command and sends the msg_data to the server,
     * finalizing the mail transaction. $msg_data is the message
     * that is to be sent with the headers. Each header needs to be
     * on a single line followed by a <CRLF> with the message headers
     * and the message body being separated by an additional <CRLF>.
     * Implements RFC 821: DATA <CRLF>.
     *
     * @param string $msg_data Message data to send
     *
     * @return bool
     */
    public function data($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 LE)
         * 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(["\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) {
            $lines_out = [];
            if ($in_headers && $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 $line_out) {
                //Dot-stuffing as per RFC5321 section 4.5.2
                //https://www.rfc-editor.org/rfc/rfc5321#section-4.5.2
                if (!empty($line_out) && $line_out[0] === '.') {
                    $line_out = '.' . $line_out;
                }
                $this->client_send($line_out . static::LE, 'DATA');
            }
        }

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

return $result;
    }

/**
     * Send an SMTP HELO or EHLO command.
     * Used to identify the sending server to the receiving server.
     * This makes sure that client and server are in a known state.
     * Implements RFC 821: HELO <SP> <domain> <CRLF>
     * and RFC 2821 EHLO.
     *
     * @param string $host The host name or IP to connect to
     *
     * @return bool
     */
    public function hello($host = '')
    {
        //Try extended hello first (RFC 2821)
        if ($this->sendHello('EHLO', $host)) {
            return true;
        }

//Some servers shut down the SMTP service here (RFC 5321)
        if (substr($this->helo_rply, 0, 3) == '421') {
            return false;
        }

return $this->sendHello('HELO', $host);
    }

/**
     * Send an SMTP HELO or EHLO command.
     * Low-level implementation used by hello().
     *
     * @param string $hello The HELO string
     * @param string $host  The hostname to say we are
     *
     * @return bool
     *
     * @see hello()
     */
    protected function sendHello($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;
    }

/**
     * Parse a reply to HELO/EHLO command to discover server extensions.
     * In case of HELO, the only parameter that can be discovered is a server name.
     *
     * @param string $type `HELO` or `EHLO`
     */
    protected function parseHelloFields($type)
    {
        $this->server_caps = [];
        $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 = [];
                            }
                            break;
                        default:
                            $fields = true;
                    }
                }
                $this->server_caps[$name] = $fields;
            }
        }
    }

/**
     * Send an SMTP MAIL command.
     * Starts a mail transaction from the email address specified in
     * $from. Returns true if successful or false otherwise. If True
     * the mail transaction is started and then one or more recipient
     * commands may be called followed by a data command.
     * Implements RFC 821: MAIL <SP> FROM:<reverse-path> <CRLF> and
     * two extensions, namely XVERP and SMTPUTF8.
     *
     * The server's EHLO response is not checked. If use of either
     * extensions is enabled even though the server does not support
     * that, mail submission will fail.
     *
     * XVERP is documented at https://www.postfix.org/VERP_README.html
     * and SMTPUTF8 is specified in RFC 6531.
     *
     * @param string $from Source address of this message
     *
     * @return bool
     */
    public function mail($from)
    {
        $useVerp = ($this->do_verp ? ' XVERP' : '');
        $useSmtputf8 = ($this->do_smtputf8 ? ' SMTPUTF8' : '');

return $this->sendCommand(
            'MAIL FROM',
            'MAIL FROM:<' . $from . '>' . $useSmtputf8 . $useVerp,
            250
        );
    }

/**
     * Send an SMTP QUIT command.
     * Closes the socket if there is no error or the $close_on_error argument is true.
     * Implements from RFC 821: QUIT <CRLF>.
     *
     * @param bool $close_on_error Should the connection close if an error occurs?
     *
     * @return bool
     */
    public function quit($close_on_error = true)
    {
        $noerror = $this->sendCommand('QUIT', 'QUIT', 221);
        $err = $this->error; //Save any error
        if ($noerror || $close_on_error) {
            $this->close();
            $this->error = $err; //Restore any error from the quit command
        }

return $noerror;
    }

/**
     * Send an SMTP RCPT command.
     * Sets the TO argument to $toaddr.
     * Returns true if the recipient was accepted false if it was rejected.
     * Implements from RFC 821: RCPT <SP> TO:<forward-path> <CRLF>.
     *
     * @param string $address The address the message is being sent to
     * @param string $dsn     Comma separated list of DSN notifications. NEVER, SUCCESS, FAILURE
     *                        or DELAY. If you specify NEVER all other notifications are ignored.
     *
     * @return bool
     */
    public function recipient($address, $dsn = '')
    {
        if (empty($dsn)) {
            $rcpt = 'RCPT TO:<' . $address . '>';
        } else {
            $dsn = strtoupper($dsn);
            $notify = [];

if (strpos($dsn, 'NEVER') !== false) {
                $notify[] = 'NEVER';
            } else {
                foreach (['SUCCESS', 'FAILURE', 'DELAY'] as $value) {
                    if (strpos($dsn, $value) !== false) {
                        $notify[] = $value;
                    }
                }
            }

$rcpt = 'RCPT TO:<' . $address . '> NOTIFY=' . implode(',', $notify);
        }

return $this->sendCommand(
            'RCPT TO',
            $rcpt,
            [250, 251]
        );
    }

/**
     * Send SMTP XCLIENT command to server and check its return code.
     *
     * @return bool True on success
     */
    public function xclient(array $vars)
    {
        $xclient_options = "";
        foreach ($vars as $key => $value) {
            if (in_array($key, SMTP::$xclient_allowed_attributes)) {
                $xclient_options .= " {$key}={$value}";
            }
        }
        if (!$xclient_options) {
            return true;
        }
        return $this->sendCommand('XCLIENT', 'XCLIENT' . $xclient_options, 250);
    }

/**
     * Send an SMTP RSET command.
     * Abort any transaction that is currently in progress.
     * Implements RFC 821: RSET <CRLF>.
     *
     * @return bool True on success
     */
    public function reset()
    {
        return $this->sendCommand('RSET', 'RSET', 250);
    }

/**
     * Send a command to an SMTP server and check its return code.
     *
     * @param string    $command       The command name - not sent to the server
     * @param string    $commandstring The actual command to send
     * @param int|array $expect        One or more expected integer success codes
     *
     * @return bool True on success
     */
    protected function sendCommand($command, $commandstring, $expect)
    {
        if (!$this->connected()) {
            $this->setError("Called $command without being connected");

return false;
        }
        //Reject line breaks in all commands
        if ((strpos($commandstring, "\n") !== false) || (strpos($commandstring, "\r") !== false)) {
            $this->setError("Command '$command' contained line breaks");

return false;
        }
        $this->client_send($commandstring . static::LE, $command);

$this->last_reply = $this->get_lines();
        //Fetch SMTP code and possible error code explanation
        $matches = [];
        if (preg_match('/^([\d]{3})[ -](?:([\d]\\.[\d]\\.[\d]{1,2}) )?/', $this->last_reply, $matches)) {
            $code = (int) $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
            $code = (int) substr($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, true)) {
            $this->setError(
                "$command command failed",
                $detail,
                $code,
                $code_ex
            );
            $this->edebug(
                'SMTP ERROR: ' . $this->error['error'] . ': ' . $this->last_reply,
                self::DEBUG_CLIENT
            );

return false;
        }

//Don't clear the error store when using keepalive
        if ($command !== 'RSET') {
            $this->setError('');
        }

return true;
    }

/**
     * Send an SMTP SAML command.
     * Starts a mail transaction from the email address specified in $from.
     * Returns true if successful or false otherwise. If True
     * the mail transaction is started and then one or more recipient
     * commands may be called followed by a data command. This command
     * will send the message to the users terminal if they are logged
     * in and send them an email.
     * Implements RFC 821: SAML <SP> FROM:<reverse-path> <CRLF>.
     *
     * @param string $from The address the message is from
     *
     * @return bool
     */
    public function sendAndMail($from)
    {
        return $this->sendCommand('SAML', "SAML FROM:$from", 250);
    }

/**
     * Send an SMTP VRFY command.
     *
     * @param string $name The name to verify
     *
     * @return bool
     */
    public function verify($name)
    {
        return $this->sendCommand('VRFY', "VRFY $name", [250, 251]);
    }

/**
     * Send an SMTP NOOP command.
     * Used to keep keep-alives alive, doesn't actually do anything.
     *
     * @return bool
     */
    public function noop()
    {
        return $this->sendCommand('NOOP', 'NOOP', 250);
    }

/**
     * Send an SMTP TURN command.
     * This is an optional command for SMTP that this class does not support.
     * This method is here to make the RFC821 Definition complete for this class
     * and _may_ be implemented in future.
     * Implements from RFC 821: TURN <CRLF>.
     *
     * @return bool
     */
    public function turn()
    {
        $this->setError('The SMTP TURN command is not implemented');
        $this->edebug('SMTP NOTICE: ' . $this->error['error'], self::DEBUG_CLIENT);

return false;
    }

/**
     * Send raw data to the server.
     *
     * @param string $data    The data to send
     * @param string $command Optionally, the command this is part of, used only for controlling debug output
     *
     * @return int|bool The number of bytes sent to the server or false on error
     */
    public function client_send($data, $command = '')
    {
        //If SMTP transcripts are left enabled, or debug output is posted online
        //it can leak credentials, so hide credentials in all but lowest level
        if (
            self::DEBUG_LOWLEVEL > $this->do_debug &&
            in_array($command, ['User & Password', 'Username', 'Password'], true)
        ) {
            $this->edebug('CLIENT -> SERVER: [credentials hidden]', self::DEBUG_CLIENT);
        } else {
            $this->edebug('CLIENT -> SERVER: ' . $data, self::DEBUG_CLIENT);
        }
        set_error_handler(function () {
            call_user_func_array([$this, 'errorHandler'], func_get_args());
        });
        $result = fwrite($this->smtp_conn, $data);
        restore_error_handler();

return $result;
    }

/**
     * Get the latest error.
     *
     * @return array
     */
    public function getError()
    {
        return $this->error;
    }

/**
     * Get SMTP extensions available on the server.
     *
     * @return array|null
     */
    public function getServerExtList()
    {
        return $this->server_caps;
    }

/**
     * Get metadata about the SMTP server from its HELO/EHLO response.
     * The method works in three ways, dependent on argument value and current state:
     *   1. HELO/EHLO has not been sent - returns null and populates $this->error.
     *   2. HELO has been sent -
     *     $name == 'HELO': returns server name
     *     $name == 'EHLO': returns boolean false
     *     $name == any other string: returns null and populates $this->error
     *   3. EHLO has been sent -
     *     $name == 'HELO'|'EHLO': returns the server name
     *     $name == any other string: if extension $name exists, returns True
     *       or its options (e.g. AUTH mechanisms supported). Otherwise returns False.
     *
     * @param string $name Name of SMTP extension or 'HELO'|'EHLO'
     *
     * @return string|bool|null
     */
    public function getServerExt($name)
    {
        if (!$this->server_caps) {
            $this->setError('No HELO/EHLO was sent');

return null;
        }

if (!array_key_exists($name, $this->server_caps)) {
            if ('HELO' === $name) {
                return $this->server_caps['EHLO'];
            }
            if ('EHLO' === $name || array_key_exists('EHLO', $this->server_caps)) {
                return false;
            }
            $this->setError('HELO handshake was used; No information about server extensions available');

return null;
        }

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

/**
     * Get the last reply from the server.
     *
     * @return string
     */
    public function getLastReply()
    {
        return $this->last_reply;
    }

/**
     * Read the SMTP server's response.
     * Either before eof or socket timeout occurs on the operation.
     * With SMTP we can tell if we have more lines to read if the
     * 4th character is '-' symbol. If it is a space then we don't
     * need to read anything else.
     *
     * @return string
     */
    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;
        }
        $selR = [$this->smtp_conn];
        $selW = null;
        while (is_resource($this->smtp_conn) && !feof($this->smtp_conn)) {
            //Must pass vars in here as params are by reference
            //solution for signals inspired by https://github.com/symfony/symfony/pull/6540
            set_error_handler(function () {
                call_user_func_array([$this, 'errorHandler'], func_get_args());
            });
            $n = stream_select($selR, $selW, $selW, $this->Timelimit);
            restore_error_handler();

if ($n === false) {
                $message = $this->getError()['detail'];

$this->edebug(
                    'SMTP -> get_lines(): select failed (' . $message . ')',
                    self::DEBUG_LOWLEVEL
                );

//stream_select returns false when the `select` system call is interrupted
                //by an incoming signal, try the select again
                if (
                    stripos($message, 'interrupted system call') !== false ||
                    (
                        // on applications with a different locale than english, the message above is not found because
                        // it's translated. So we also check for the SOCKET_EINTR constant which is defined under
                        // Windows and UNIX-like platforms (if available on the platform).
                        defined('SOCKET_EINTR') &&
                        stripos($message, 'stream_select(): Unable to select [' . SOCKET_EINTR . ']') !== false
                    )
                ) {
                    $this->edebug(
                        'SMTP -> get_lines(): retrying stream_select',
                        self::DEBUG_LOWLEVEL
                    );
                    $this->setError('');
                    continue;
                }

break;
            }

if (!$n) {
                $this->edebug(
                    'SMTP -> get_lines(): select timed-out in (' . $this->Timelimit . ' sec)',
                    self::DEBUG_LOWLEVEL
                );
                break;
            }

//Deliberate noise suppression - errors are handled afterwards
            $str = @fgets($this->smtp_conn, self::MAX_REPLY_LENGTH);
            $this->edebug('SMTP INBOUND: "' . trim($str) . '"', self::DEBUG_LOWLEVEL);
            $data .= $str;
            //If response is only 3 chars (not valid, but RFC5321 S4.2 says it must be handled),
            //or 4th character is a space or a line break char, we are done reading, break the loop.
            //String array access is a significant micro-optimisation over strlen
            if (!isset($str[3]) || $str[3] === ' ' || $str[3] === "\r" || $str[3] === "\n") {
                break;
            }
            //Timed-out? Log and break
            $info = stream_get_meta_data($this->smtp_conn);
            if ($info['timed_out']) {
                $this->edebug(
                    'SMTP -> get_lines(): stream timed-out (' . $this->Timeout . ' sec)',
                    self::DEBUG_LOWLEVEL
                );
                break;
            }
            //Now check if reads took too long
            if ($endtime && time() > $endtime) {
                $this->edebug(
                    'SMTP -> get_lines(): timelimit reached (' .
                    $this->Timelimit . ' sec)',
                    self::DEBUG_LOWLEVEL
                );
                break;
            }
        }

return $data;
    }

/**
     * Enable or disable VERP address generation.
     *
     * @param bool $enabled
     */
    public function setVerp($enabled = false)
    {
        $this->do_verp = $enabled;
    }

/**
     * Get VERP address generation mode.
     *
     * @return bool
     */
    public function getVerp()
    {
        return $this->do_verp;
    }

/**
     * Enable or disable use of SMTPUTF8.
     *
     * @param bool $enabled
     */
    public function setSMTPUTF8($enabled = false)
    {
        $this->do_smtputf8 = $enabled;
    }

/**
     * Get SMTPUTF8 use.
     *
     * @return bool
     */
    public function getSMTPUTF8()
    {
        return $this->do_smtputf8;
    }

/**
     * Set error messages and codes.
     *
     * @param string $message      The error message
     * @param string $detail       Further detail on the error
     * @param string $smtp_code    An associated SMTP error code
     * @param string $smtp_code_ex Extended SMTP code
     */
    protected function setError($message, $detail = '', $smtp_code = '', $smtp_code_ex = '')
    {
        $this->error = [
            'error' => $message,
            'detail' => $detail,
            'smtp_code' => $smtp_code,
            'smtp_code_ex' => $smtp_code_ex,
        ];
    }

/**
     * Set debug output method.
     *
     * @param string|callable $method The name of the mechanism to use for debugging output, or a callable to handle it
     */
    public function setDebugOutput($method = 'echo')
    {
        $this->Debugoutput = $method;
    }

/**
     * Get debug output method.
     *
     * @return string
     */
    public function getDebugOutput()
    {
        return $this->Debugoutput;
    }

/**
     * Set debug output level.
     *
     * @param int $level
     */
    public function setDebugLevel($level = 0)
    {
        $this->do_debug = $level;
    }

/**
     * Get debug output level.
     *
     * @return int
     */
    public function getDebugLevel()
    {
        return $this->do_debug;
    }

/**
     * Set SMTP timeout.
     *
     * @param int $timeout The timeout duration in seconds
     */
    public function setTimeout($timeout = 0)
    {
        $this->Timeout = $timeout;
    }

/**
     * Get SMTP timeout.
     *
     * @return int
     */
    public function getTimeout()
    {
        return $this->Timeout;
    }

/**
     * Reports an error number and string.
     *
     * @param int    $errno   The error number returned by PHP
     * @param string $errmsg  The error message returned by PHP
     * @param string $errfile The file the error occurred in
     * @param int    $errline The line number the error occurred on
     */
    protected function errorHandler($errno, $errmsg, $errfile = '', $errline = 0)
    {
        $notice = 'Connection failed.';
        $this->setError(
            $notice,
            $errmsg,
            (string) $errno
        );
        $this->edebug(
            "$notice Error #$errno: $errmsg [$errfile line $errline]",
            self::DEBUG_CONNECTION
        );
    }

/**
     * Extract and return the ID of the last SMTP transaction based on
     * a list of patterns provided in SMTP::$smtp_transaction_id_patterns.
     * Relies on the host providing the ID in response to a DATA command.
     * If no reply has been received yet, it will return null.
     * If no pattern was matched, it will return false.
     *
     * @return bool|string|null
     */
    protected function recordLastTransactionID()
    {
        $reply = $this->getLastReply();

if (empty($reply)) {
            $this->last_smtp_transaction_id = null;
        } else {
            $this->last_smtp_transaction_id = false;
            foreach ($this->smtp_transaction_id_patterns as $smtp_transaction_id_pattern) {
                $matches = [];
                if (preg_match($smtp_transaction_id_pattern, $reply, $matches)) {
                    $this->last_smtp_transaction_id = trim($matches[1]);
                    break;
                }
            }
        }

return $this->last_smtp_transaction_id;
    }

/**
     * Get the queue/transaction ID of the last SMTP transaction
     * If no reply has been received yet, it will return null.
     * If no pattern was matched, it will return false.
     *
     * @return bool|string|null
     *
     * @see recordLastTransactionID()
     */
    public function getLastTransactionID()
    {
        return $this->last_smtp_transaction_id;
    }
}

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