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<?php
/**
* Pure-PHP ssh-agent client.
*
* PHP version 5
*
* Here are some examples of how to use this library:
* <code>
* <?php
* include 'phpseclib/autoload.php';
*
* $agent = new \phpseclib\System\SSH\Agent();
*
* $ssh = new \phpseclib\Net\SSH2('www.domain.tld');
* if (!$ssh->login('username', $agent)) {
* exit('Login Failed');
* }
*
* echo $ssh->exec('pwd');
* echo $ssh->exec('ls -la');
* ?>
* </code>
*
* @category System
* @package SSH\Agent
* @author Jim Wigginton <[email protected]>
* @copyright 2014 Jim Wigginton
* @license http://www.opensource.org/licenses/mit-license.html MIT License
* @link http://phpseclib.sourceforge.net
* @internal See http://api.libssh.org/rfc/PROTOCOL.agent
*/
namespace phpseclib\System\SSH;
use phpseclib\Crypt\RSA;
use phpseclib\System\SSH\Agent\Identity;
/**
* Pure-PHP ssh-agent client identity factory
*
* requestIdentities() method pumps out \phpseclib\System\SSH\Agent\Identity objects
*
* @package SSH\Agent
* @author Jim Wigginton <[email protected]>
* @access public
*/
class Agent
{
/**#@+
* Message numbers
*
* @access private
*/
// to request SSH1 keys you have to use SSH_AGENTC_REQUEST_RSA_IDENTITIES (1)
const SSH_AGENTC_REQUEST_IDENTITIES = 11;
// this is the SSH2 response; the SSH1 response is SSH_AGENT_RSA_IDENTITIES_ANSWER (2).
const SSH_AGENT_IDENTITIES_ANSWER = 12;
// the SSH1 request is SSH_AGENTC_RSA_CHALLENGE (3)
const SSH_AGENTC_SIGN_REQUEST = 13;
// the SSH1 response is SSH_AGENT_RSA_RESPONSE (4)
const SSH_AGENT_SIGN_RESPONSE = 14;
/**#@-*/
/**@+
* Agent forwarding status
*
* @access private
*/
// no forwarding requested and not active
const FORWARD_NONE = 0;
// request agent forwarding when opportune
const FORWARD_REQUEST = 1;
// forwarding has been request and is active
const FORWARD_ACTIVE = 2;
/**#@-*/
/**
* Unused
*/
const SSH_AGENT_FAILURE = 5;
/**
* Socket Resource
*
* @var resource
* @access private
*/
var $fsock;
/**
* Agent forwarding status
*
* @access private
*/
var $forward_status = self::FORWARD_NONE;
/**
* Buffer for accumulating forwarded authentication
* agent data arriving on SSH data channel destined
* for agent unix socket
*
* @access private
*/
var $socket_buffer = '';
/**
* Tracking the number of bytes we are expecting
* to arrive for the agent socket on the SSH data
* channel
*/
var $expected_bytes = 0;
/**
* Default Constructor
*
* @return \phpseclib\System\SSH\Agent
* @access public
*/
function __construct($address = null)
{
if (!$address) {
switch (true) {
case isset($_SERVER['SSH_AUTH_SOCK']):
$address = $_SERVER['SSH_AUTH_SOCK'];
break;
case isset($_ENV['SSH_AUTH_SOCK']):
$address = $_ENV['SSH_AUTH_SOCK'];
break;
default:
user_error('SSH_AUTH_SOCK not found');
return false;
}
}
$this->fsock = fsockopen('unix://' . $address, 0, $errno, $errstr);
if (!$this->fsock) {
user_error("Unable to connect to ssh-agent (Error $errno: $errstr)");
}
}
/**
* Request Identities
*
* See "2.5.2 Requesting a list of protocol 2 keys"
* Returns an array containing zero or more \phpseclib\System\SSH\Agent\Identity objects
*
* @return array
* @access public
*/
function requestIdentities()
{
if (!$this->fsock) {
return array();
}
$packet = pack('NC', 1, self::SSH_AGENTC_REQUEST_IDENTITIES);
if (strlen($packet) != fputs($this->fsock, $packet)) {
user_error('Connection closed while requesting identities');
return array();
}
$temp = fread($this->fsock, 4);
if (strlen($temp) != 4) {
user_error('Connection closed while requesting identities');
return array();
}
$length = current(unpack('N', $temp));
$type = ord(fread($this->fsock, 1));
if ($type != self::SSH_AGENT_IDENTITIES_ANSWER) {
user_error('Unable to request identities');
return array();
}
$identities = array();
$temp = fread($this->fsock, 4);
if (strlen($temp) != 4) {
user_error('Connection closed while requesting identities');
return array();
}
$keyCount = current(unpack('N', $temp));
for ($i = 0; $i < $keyCount; $i++) {
$temp = fread($this->fsock, 4);
if (strlen($temp) != 4) {
user_error('Connection closed while requesting identities');
return array();
}
$length = current(unpack('N', $temp));
$key_blob = fread($this->fsock, $length);
if (strlen($key_blob) != $length) {
user_error('Connection closed while requesting identities');
return array();
}
$key_str = 'ssh-rsa ' . base64_encode($key_blob);
$temp = fread($this->fsock, 4);
if (strlen($temp) != 4) {
user_error('Connection closed while requesting identities');
return array();
}
$length = current(unpack('N', $temp));
if ($length) {
$temp = fread($this->fsock, $length);
if (strlen($temp) != $length) {
user_error('Connection closed while requesting identities');
return array();
}
$key_str.= ' ' . $temp;
}
$length = current(unpack('N', substr($key_blob, 0, 4)));
$key_type = substr($key_blob, 4, $length);
switch ($key_type) {
case 'ssh-rsa':
$key = new RSA();
$key->loadKey($key_str);
break;
case 'ssh-dss':
// not currently supported
break;
}
// resources are passed by reference by default
if (isset($key)) {
$identity = new Identity($this->fsock);
$identity->setPublicKey($key);
$identity->setPublicKeyBlob($key_blob);
$identities[] = $identity;
unset($key);
}
}
return $identities;
}
/**
* Signal that agent forwarding should
* be requested when a channel is opened
*
* @param Net_SSH2 $ssh
* @return bool
* @access public
*/
function startSSHForwarding($ssh)
{
if ($this->forward_status == self::FORWARD_NONE) {
$this->forward_status = self::FORWARD_REQUEST;
}
}
/**
* Request agent forwarding of remote server
*
* @param Net_SSH2 $ssh
* @return bool
* @access private
*/
function _request_forwarding($ssh)
{
$request_channel = $ssh->_get_open_channel();
if ($request_channel === false) {
return false;
}
$packet = pack(
'CNNa*C',
NET_SSH2_MSG_CHANNEL_REQUEST,
$ssh->server_channels[$request_channel],
strlen('[email protected]'),
'[email protected]',
1
);
$ssh->channel_status[$request_channel] = NET_SSH2_MSG_CHANNEL_REQUEST;
if (!$ssh->_send_binary_packet($packet)) {
return false;
}
$response = $ssh->_get_channel_packet($request_channel);
if ($response === false) {
return false;
}
$ssh->channel_status[$request_channel] = NET_SSH2_MSG_CHANNEL_OPEN;
$this->forward_status = self::FORWARD_ACTIVE;
return true;
}
/**
* On successful channel open
*
* This method is called upon successful channel
* open to give the SSH Agent an opportunity
* to take further action. i.e. request agent forwarding
*
* @param Net_SSH2 $ssh
* @access private
*/
function _on_channel_open($ssh)
{
if ($this->forward_status == self::FORWARD_REQUEST) {
$this->_request_forwarding($ssh);
}
}
/**
* Forward data to SSH Agent and return data reply
*
* @param string $data
* @return data from SSH Agent
* @access private
*/
function _forward_data($data)
{
if ($this->expected_bytes > 0) {
$this->socket_buffer.= $data;
$this->expected_bytes -= strlen($data);
} else {
$agent_data_bytes = current(unpack('N', $data));
$current_data_bytes = strlen($data);
$this->socket_buffer = $data;
if ($current_data_bytes != $agent_data_bytes + 4) {
$this->expected_bytes = ($agent_data_bytes + 4) - $current_data_bytes;
return false;
}
}
if (strlen($this->socket_buffer) != fwrite($this->fsock, $this->socket_buffer)) {
user_error('Connection closed attempting to forward data to SSH agent');
return false;
}
$this->socket_buffer = '';
$this->expected_bytes = 0;
$temp = fread($this->fsock, 4);
if (strlen($temp) != 4) {
user_error('Connection closed while reading data response');
return false;
}
$agent_reply_bytes = current(unpack('N', $temp));
$agent_reply_data = fread($this->fsock, $agent_reply_bytes);
if (strlen($agent_reply_data) != $agent_reply_bytes) {
user_error('Connection closed while reading data response');
return false;
}
$agent_reply_data = current(unpack('a*', $agent_reply_data));
return pack('Na*', $agent_reply_bytes, $agent_reply_data);
}
}
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