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<?php/***
 * Copyright 2016 Igor Dyshlenko
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */
 
 /**
 * Ssh2Connector
 * The class provides basic functions for connecting and exchanging data with
 * the ssh2 server.
 *
 * @author Igor Dyshlenko
 * @category Console
 * @license https://opensource.org/licenses/MIT MIT
 */
 
 class Ssh2Connector implements ShellConnector {
 protected $host, $port, $userName;
 protected $callbacks;
 
 protected
 $connection        = null,
 $connected        = false,
 $connErrCode    = null,
 $connErrMsg        = '',
 $connErrLang    = null;
 
 protected $shell    = null;
 protected $logger    = null;
 protected $writeBuffer    =    null;
 
 /**
 * Constructor
 * @param string $host
 * @param int $port - default 22.
 * @param mixed $logger - PEAR Log class object for logging all events, any
 *                        other value is ignored.
 * @throws BadFunctionCallException if ssh2_connect() function doesn't exist.
 * @throws LogicException if connect to ssh server is fail.
 */
 public function __construct($host, $port=22, $logger=null) {
 $this->logger = new LogWrapper($logger);
 
 if (!function_exists('ssh2_connect')) {
 $msg = 'Function ssh2_connect doesn\'t exist.';
 $this->logger->err(__METHOD__ . ': ' . $msg);
 throw new BadFunctionCallException($msg);
 }
 
 $this->host = $host;
 $this->port = $port;
 $this->callbacks = array('disconnect' => array($this, 'ssh_disconnect'));
 if (!($this->connection = ssh2_connect($host, $port, null, $this->callbacks))) {
 $msg = 'Fail: unable to establish connection to ' . $host . ':' . $port .
 "\n" . $this->connErrCode . ': ' . $this->connErrMsg;
 $this->logger->err(__METHOD__ . ': ' . $msg);
 throw new LogicException($msg);
 }
 $this->logger->debug(__METHOD__ . ': Connection to ' . $host . ':' . $port . ' established.');
 $this->connected = true;
 }
 
 public function __destruct() {
 $this->logout();
 $this->disconnect();
 }
 
 /**
 * Login function
 * @param string $userName - user name (login).
 * @param string $pass - password.
 * @return bool true if success.
 * @throws LogicException if authentication error.
 */
 public function login($userName, $pass='') {
 if (!ssh2_auth_password($this->connection, $userName, $pass)) {
 $msg = 'Fail: unable to authenticate user ' . $userName;
 $this->logger->err(__METHOD__ . ': ' . $msg);
 throw new LogicException($msg);
 }
 
 $this->userName = $userName;
 
 if (!($this->shell = ssh2_shell($this->connection, 'vt102', null, 80, 40, SSH2_TERM_UNIT_CHARS))) {
 $msg = 'Fail: unable to establish shell.';
 $this->logger->err(__METHOD__ . ': ' . $msg);
 throw new LogicException($msg);
 }
 
 $this->loggedIn = true;
 $this->logger->debug(__METHOD__ . ': user ' . $userName . ' logged in.');
 
 return true;
 }
 
 /**
 * Logout function
 * @return bool true if success, false if fail.
 */
 public function logout() {
 if ($this->isLoggedIn()) {
 fclose($this->shell);
 $this->logger->debug(__METHOD__ . ': user ' . $this->userName . ' logged out.');
 
 return true;
 }
 
 return false;
 }
 
 public function disconnect() {}
 
 /**
 * Get "is ssh2 connected" state
 * @return bool
 */
 public function isConnected() {
 return $this->connected;
 }
 
 /**
 * Get "is logged in" state
 * @return bool
 */
 public function isLoggedIn() {
 return is_resource($this->shell);
 }
 
 /**
 * Callback "disconnect" function for ssh2_connect().
 * @param int $reason - Error Number
 * @param string $message - Error message
 * @param mixed $language
 */
 public function ssh_disconnect($reason, $message, $language) {
 $this->connected = false;
 $this->connErrCode = $reason;
 $this->connErrMsg = $message;
 $this->connErrLang = $language;
 $this->logger->debug(__METHOD__ . ': SSH2 connection ' . $this->userName . '@' . $this->host .
 ':' . $this->port . ' closed. ' . $reason . ': ' . $message);
 }
 
 /**
 * Get Error Message returned ssh2_connect() function.
 * @return string error message if error, empty string ('') otherwise
 */
 public function getError() {
 return $this->connErrMsg;
 }
 
 /**
 * Get Error Number returned ssh2_connect() function.
 * @return mixed - int error code if error, NULL otherwise
 */
 public function getErrno() {
 return $this->connErrCode;
 }
 
 /**
 * Read character from stream.
 * @return mixed - string (readed character) or FALSE if EOF or error.
 */
 public function read() {
 
 if (!($this->isLoggedIn() && $this->isConnected()) || feof($this->shell)){
 $this->logger->debug(__METHOD__ . ': SSH2 connection ' . $this->userName . '@' . $this->host .
 ':' . $this->port . ' closed or logged out or feof().');
 return false;
 }
 
 $char = fread($this->shell, 1);
 
 if ($char === '' && !feof($this->shell)) {
 usleep(100000);
 $char = fread($this->shell, 1);
 }
 
 if ($char === false) {
 $this->logger->debug(__METHOD__ . ': Error read from stream.');
 }
 
 return $char;
 }
 
 /**
 * Write data to ssh connection.
 * @param string $data - data for write
 * @return int - number of written chars or FALSE if error
 */
 public function write($data) {
 $total = strlen($data);
 $written = $n = 0;
 $buf = $data;
 
 while ($written < $total){
 $buf = substr($buf,$n);
 if (($n = fwrite($this->shell,$buf,4096)) === false) {
 if (feof($this->shell)) {
 $this->logger->debug(__METHOD__ . ': ' . $this->userName . '@' . $this->host . ' disconnected.');
 break;
 } else {
 $msg = 'Error writing to socket.';
 $this->logger->err(__METHOD__ . ': ' . $msg);
 throw new RuntimeException($msg);
 }
 }
 $written += $n;
 }
 
 fflush($this->shell);
 
 return !$this->connected || feof($this->shell) ? false : $written;
 }
 }
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