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   1  <?php
   2  
   3  /**
   4   * Pure-PHP ssh-agent client.
   5   *
   6   * PHP version 5
   7   *
   8   * Here are some examples of how to use this library:
   9   * <code>
  10   * <?php
  11   *    include 'vendor/autoload.php';
  12   *
  13   *    $agent = new \phpseclib\System\SSH\Agent();
  14   *
  15   *    $ssh = new \phpseclib\Net\SSH2('www.domain.tld');
  16   *    if (!$ssh->login('username', $agent)) {
  17   *        exit('Login Failed');
  18   *    }
  19   *
  20   *    echo $ssh->exec('pwd');
  21   *    echo $ssh->exec('ls -la');
  22   * ?>
  23   * </code>
  24   *
  25   * @category  System
  26   * @package   SSH\Agent
  27   * @author    Jim Wigginton <terrafrost@php.net>
  28   * @copyright 2014 Jim Wigginton
  29   * @license   http://www.opensource.org/licenses/mit-license.html  MIT License
  30   * @link      http://phpseclib.sourceforge.net
  31   * @internal  See http://api.libssh.org/rfc/PROTOCOL.agent
  32   */
  33  
  34  namespace phpseclib\System\SSH;
  35  
  36  use phpseclib\Crypt\RSA;
  37  use phpseclib\System\SSH\Agent\Identity;
  38  
  39  /**
  40   * Pure-PHP ssh-agent client identity factory
  41   *
  42   * requestIdentities() method pumps out \phpseclib\System\SSH\Agent\Identity objects
  43   *
  44   * @package SSH\Agent
  45   * @author  Jim Wigginton <terrafrost@php.net>
  46   * @access  public
  47   */
  48  class Agent
  49  {
  50      /**#@+
  51       * Message numbers
  52       *
  53       * @access private
  54       */
  55      // to request SSH1 keys you have to use SSH_AGENTC_REQUEST_RSA_IDENTITIES (1)
  56      const SSH_AGENTC_REQUEST_IDENTITIES = 11;
  57      // this is the SSH2 response; the SSH1 response is SSH_AGENT_RSA_IDENTITIES_ANSWER (2).
  58      const SSH_AGENT_IDENTITIES_ANSWER = 12;
  59      // the SSH1 request is SSH_AGENTC_RSA_CHALLENGE (3)
  60      const SSH_AGENTC_SIGN_REQUEST = 13;
  61      // the SSH1 response is SSH_AGENT_RSA_RESPONSE (4)
  62      const SSH_AGENT_SIGN_RESPONSE = 14;
  63      /**#@-*/
  64  
  65      /**@+
  66       * Agent forwarding status
  67       *
  68       * @access private
  69       */
  70      // no forwarding requested and not active
  71      const FORWARD_NONE = 0;
  72      // request agent forwarding when opportune
  73      const FORWARD_REQUEST = 1;
  74      // forwarding has been request and is active
  75      const FORWARD_ACTIVE = 2;
  76      /**#@-*/
  77  
  78      /**
  79       * Unused
  80       */
  81      const SSH_AGENT_FAILURE = 5;
  82  
  83      /**
  84       * Socket Resource
  85       *
  86       * @var resource
  87       * @access private
  88       */
  89      var $fsock;
  90  
  91      /**
  92       * Agent forwarding status
  93       *
  94       * @access private
  95       */
  96      var $forward_status = self::FORWARD_NONE;
  97  
  98      /**
  99       * Buffer for accumulating forwarded authentication
 100       * agent data arriving on SSH data channel destined
 101       * for agent unix socket
 102       *
 103       * @access private
 104       */
 105      var $socket_buffer = '';
 106  
 107      /**
 108       * Tracking the number of bytes we are expecting
 109       * to arrive for the agent socket on the SSH data
 110       * channel
 111       */
 112      var $expected_bytes = 0;
 113  
 114      /**
 115       * Default Constructor
 116       *
 117       * @return \phpseclib\System\SSH\Agent
 118       * @access public
 119       */
 120      function __construct($address = null)
 121      {
 122          if (!$address) {
 123              switch (true) {
 124                  case isset($_SERVER['SSH_AUTH_SOCK']):
 125                      $address = $_SERVER['SSH_AUTH_SOCK'];
 126                      break;
 127                  case isset($_ENV['SSH_AUTH_SOCK']):
 128                      $address = $_ENV['SSH_AUTH_SOCK'];
 129                      break;
 130                  default:
 131                      user_error('SSH_AUTH_SOCK not found');
 132                      return false;
 133              }
 134          }
 135  
 136          if (in_array('unix', stream_get_transports())) {
 137              $this->fsock = fsockopen('unix://' . $address, 0, $errno, $errstr);
 138              if (!$this->fsock) {
 139                  user_error("Unable to connect to ssh-agent (Error $errno: $errstr)");
 140              }
 141          } else {
 142              if (substr($address, 0, 9) != '\\\\.\\pipe\\' || strpos(substr($address, 9), '\\') !== false) {
 143                  user_error('Address is not formatted as a named pipe should be');
 144              } else {
 145                  $this->fsock = fopen($address, 'r+b');
 146                  if (!$this->fsock) {
 147                      user_error('Unable to open address');
 148                  }
 149              }
 150          }
 151      }
 152  
 153      /**
 154       * Request Identities
 155       *
 156       * See "2.5.2 Requesting a list of protocol 2 keys"
 157       * Returns an array containing zero or more \phpseclib\System\SSH\Agent\Identity objects
 158       *
 159       * @return array
 160       * @access public
 161       */
 162      function requestIdentities()
 163      {
 164          if (!$this->fsock) {
 165              return array();
 166          }
 167  
 168          $packet = pack('NC', 1, self::SSH_AGENTC_REQUEST_IDENTITIES);
 169          if (strlen($packet) != fputs($this->fsock, $packet)) {
 170              user_error('Connection closed while requesting identities');
 171              return array();
 172          }
 173  
 174          $temp = fread($this->fsock, 4);
 175          if (strlen($temp) != 4) {
 176              user_error('Connection closed while requesting identities');
 177              return array();
 178          }
 179          $length = current(unpack('N', $temp));
 180          $type = ord(fread($this->fsock, 1));
 181          if ($type != self::SSH_AGENT_IDENTITIES_ANSWER) {
 182              user_error('Unable to request identities');
 183              return array();
 184          }
 185  
 186          $identities = array();
 187          $temp = fread($this->fsock, 4);
 188          if (strlen($temp) != 4) {
 189              user_error('Connection closed while requesting identities');
 190              return array();
 191          }
 192          $keyCount = current(unpack('N', $temp));
 193          for ($i = 0; $i < $keyCount; $i++) {
 194              $temp = fread($this->fsock, 4);
 195              if (strlen($temp) != 4) {
 196                  user_error('Connection closed while requesting identities');
 197                  return array();
 198              }
 199              $length = current(unpack('N', $temp));
 200              $key_blob = fread($this->fsock, $length);
 201              if (strlen($key_blob) != $length) {
 202                  user_error('Connection closed while requesting identities');
 203                  return array();
 204              }
 205              $key_str = 'ssh-rsa ' . base64_encode($key_blob);
 206              $temp = fread($this->fsock, 4);
 207              if (strlen($temp) != 4) {
 208                  user_error('Connection closed while requesting identities');
 209                  return array();
 210              }
 211              $length = current(unpack('N', $temp));
 212              if ($length) {
 213                  $temp = fread($this->fsock, $length);
 214                  if (strlen($temp) != $length) {
 215                      user_error('Connection closed while requesting identities');
 216                      return array();
 217                  }
 218                  $key_str.= ' ' . $temp;
 219              }
 220              $length = current(unpack('N', substr($key_blob, 0, 4)));
 221              $key_type = substr($key_blob, 4, $length);
 222              switch ($key_type) {
 223                  case 'ssh-rsa':
 224                      $key = new RSA();
 225                      $key->loadKey($key_str);
 226                      break;
 227                  case 'ssh-dss':
 228                      // not currently supported
 229                      break;
 230              }
 231              // resources are passed by reference by default
 232              if (isset($key)) {
 233                  $identity = new Identity($this->fsock);
 234                  $identity->setPublicKey($key);
 235                  $identity->setPublicKeyBlob($key_blob);
 236                  $identities[] = $identity;
 237                  unset($key);
 238              }
 239          }
 240  
 241          return $identities;
 242      }
 243  
 244      /**
 245       * Signal that agent forwarding should
 246       * be requested when a channel is opened
 247       *
 248       * @return bool
 249       * @access public
 250       */
 251      function startSSHForwarding()
 252      {
 253          if ($this->forward_status == self::FORWARD_NONE) {
 254              $this->forward_status = self::FORWARD_REQUEST;
 255          }
 256      }
 257  
 258      /**
 259       * Request agent forwarding of remote server
 260       *
 261       * @param Net_SSH2 $ssh
 262       * @return bool
 263       * @access private
 264       */
 265      function _request_forwarding($ssh)
 266      {
 267          $request_channel = $ssh->_get_open_channel();
 268          if ($request_channel === false) {
 269              return false;
 270          }
 271  
 272          $packet = pack(
 273              'CNNa*C',
 274              NET_SSH2_MSG_CHANNEL_REQUEST,
 275              $ssh->server_channels[$request_channel],
 276              strlen('auth-agent-req@openssh.com'),
 277              'auth-agent-req@openssh.com',
 278              1
 279          );
 280  
 281          $ssh->channel_status[$request_channel] = NET_SSH2_MSG_CHANNEL_REQUEST;
 282  
 283          if (!$ssh->_send_binary_packet($packet)) {
 284              return false;
 285          }
 286  
 287          $response = $ssh->_get_channel_packet($request_channel);
 288          if ($response === false) {
 289              return false;
 290          }
 291  
 292          $ssh->channel_status[$request_channel] = NET_SSH2_MSG_CHANNEL_OPEN;
 293          $this->forward_status = self::FORWARD_ACTIVE;
 294  
 295          return true;
 296      }
 297  
 298      /**
 299       * On successful channel open
 300       *
 301       * This method is called upon successful channel
 302       * open to give the SSH Agent an opportunity
 303       * to take further action. i.e. request agent forwarding
 304       *
 305       * @param Net_SSH2 $ssh
 306       * @access private
 307       */
 308      function _on_channel_open($ssh)
 309      {
 310          if ($this->forward_status == self::FORWARD_REQUEST) {
 311              $this->_request_forwarding($ssh);
 312          }
 313      }
 314  
 315      /**
 316       * Forward data to SSH Agent and return data reply
 317       *
 318       * @param string $data
 319       * @return data from SSH Agent
 320       * @access private
 321       */
 322      function _forward_data($data)
 323      {
 324          if ($this->expected_bytes > 0) {
 325              $this->socket_buffer.= $data;
 326              $this->expected_bytes -= strlen($data);
 327          } else {
 328              $agent_data_bytes = current(unpack('N', $data));
 329              $current_data_bytes = strlen($data);
 330              $this->socket_buffer = $data;
 331              if ($current_data_bytes != $agent_data_bytes + 4) {
 332                  $this->expected_bytes = ($agent_data_bytes + 4) - $current_data_bytes;
 333                  return false;
 334              }
 335          }
 336  
 337          if (strlen($this->socket_buffer) != fwrite($this->fsock, $this->socket_buffer)) {
 338              user_error('Connection closed attempting to forward data to SSH agent');
 339              return false;
 340          }
 341  
 342          $this->socket_buffer = '';
 343          $this->expected_bytes = 0;
 344  
 345          $temp = fread($this->fsock, 4);
 346          if (strlen($temp) != 4) {
 347              user_error('Connection closed while reading data response');
 348              return false;
 349          }
 350          $agent_reply_bytes = current(unpack('N', $temp));
 351  
 352          $agent_reply_data = fread($this->fsock, $agent_reply_bytes);
 353          if (strlen($agent_reply_data) != $agent_reply_bytes) {
 354              user_error('Connection closed while reading data response');
 355              return false;
 356          }
 357          $agent_reply_data = current(unpack('a*', $agent_reply_data));
 358  
 359          return pack('Na*', $agent_reply_bytes, $agent_reply_data);
 360      }
 361  }