461 lines
13 KiB
PHP
461 lines
13 KiB
PHP
<?php
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/**
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* Pure-PHP ssh-agent client.
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*
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* PHP versions 4 and 5
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*
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* Here are some examples of how to use this library:
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* <code>
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* <?php
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* include 'System/SSH/Agent.php';
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* include 'Net/SSH2.php';
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*
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* $agent = new System_SSH_Agent();
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*
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* $ssh = new Net_SSH2('www.domain.tld');
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* if (!$ssh->login('username', $agent)) {
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* exit('Login Failed');
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* }
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*
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* echo $ssh->exec('pwd');
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* echo $ssh->exec('ls -la');
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* ?>
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* </code>
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*
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* LICENSE: Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*
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* @category System
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* @package System_SSH_Agent
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* @author Jim Wigginton <terrafrost@php.net>
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* @copyright 2014 Jim Wigginton
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* @license http://www.opensource.org/licenses/mit-license.html MIT License
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* @link http://phpseclib.sourceforge.net
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* @internal See http://api.libssh.org/rfc/PROTOCOL.agent
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*/
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/**#@+
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* Message numbers
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*
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* @access private
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*/
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// to request SSH1 keys you have to use SSH_AGENTC_REQUEST_RSA_IDENTITIES (1)
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define('SYSTEM_SSH_AGENTC_REQUEST_IDENTITIES', 11);
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// this is the SSH2 response; the SSH1 response is SSH_AGENT_RSA_IDENTITIES_ANSWER (2).
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define('SYSTEM_SSH_AGENT_IDENTITIES_ANSWER', 12);
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define('SYSTEM_SSH_AGENT_FAILURE', 5);
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// the SSH1 request is SSH_AGENTC_RSA_CHALLENGE (3)
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define('SYSTEM_SSH_AGENTC_SIGN_REQUEST', 13);
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// the SSH1 response is SSH_AGENT_RSA_RESPONSE (4)
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define('SYSTEM_SSH_AGENT_SIGN_RESPONSE', 14);
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/**@+
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* Agent forwarding status
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*
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* @access private
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*/
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// no forwarding requested and not active
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define('SYSTEM_SSH_AGENT_FORWARD_NONE', 0);
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// request agent forwarding when opportune
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define('SYSTEM_SSH_AGENT_FORWARD_REQUEST', 1);
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// forwarding has been request and is active
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define('SYSTEM_SSH_AGENT_FORWARD_ACTIVE', 2);
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/**#@-*/
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/**
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* Pure-PHP ssh-agent client identity object
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*
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* Instantiation should only be performed by System_SSH_Agent class.
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* This could be thought of as implementing an interface that Crypt_RSA
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* implements. ie. maybe a Net_SSH_Auth_PublicKey interface or something.
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* The methods in this interface would be getPublicKey, setSignatureMode
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* and sign since those are the methods phpseclib looks for to perform
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* public key authentication.
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*
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* @package System_SSH_Agent
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* @author Jim Wigginton <terrafrost@php.net>
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* @access internal
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*/
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class System_SSH_Agent_Identity
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{
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/**
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* Key Object
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*
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* @var Crypt_RSA
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* @access private
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* @see System_SSH_Agent_Identity::getPublicKey()
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*/
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var $key;
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/**
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* Key Blob
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*
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* @var String
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* @access private
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* @see System_SSH_Agent_Identity::sign()
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*/
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var $key_blob;
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/**
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* Socket Resource
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*
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* @var Resource
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* @access private
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* @see System_SSH_Agent_Identity::sign()
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*/
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var $fsock;
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/**
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* Default Constructor.
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*
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* @param Resource $fsock
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* @return System_SSH_Agent_Identity
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* @access private
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*/
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function System_SSH_Agent_Identity($fsock)
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{
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$this->fsock = $fsock;
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}
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/**
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* Set Public Key
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*
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* Called by System_SSH_Agent::requestIdentities()
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*
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* @param Crypt_RSA $key
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* @access private
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*/
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function setPublicKey($key)
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{
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$this->key = $key;
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$this->key->setPublicKey();
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}
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/**
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* Set Public Key
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*
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* Called by System_SSH_Agent::requestIdentities(). The key blob could be extracted from $this->key
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* but this saves a small amount of computation.
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*
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* @param String $key_blob
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* @access private
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*/
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function setPublicKeyBlob($key_blob)
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{
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$this->key_blob = $key_blob;
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}
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/**
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* Get Public Key
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*
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* Wrapper for $this->key->getPublicKey()
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*
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* @param Integer $format optional
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* @return Mixed
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* @access public
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*/
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function getPublicKey($format = null)
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{
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return !isset($format) ? $this->key->getPublicKey() : $this->key->getPublicKey($format);
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}
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/**
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* Set Signature Mode
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*
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* Doesn't do anything as ssh-agent doesn't let you pick and choose the signature mode. ie.
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* ssh-agent's only supported mode is CRYPT_RSA_SIGNATURE_PKCS1
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*
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* @param Integer $mode
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* @access public
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*/
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function setSignatureMode($mode)
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{
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}
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/**
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* Create a signature
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*
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* See "2.6.2 Protocol 2 private key signature request"
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*
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* @param String $message
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* @return String
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* @access public
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*/
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function sign($message)
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{
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// the last parameter (currently 0) is for flags and ssh-agent only defines one flag (for ssh-dss): SSH_AGENT_OLD_SIGNATURE
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$packet = pack('CNa*Na*N', SYSTEM_SSH_AGENTC_SIGN_REQUEST, strlen($this->key_blob), $this->key_blob, strlen($message), $message, 0);
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$packet = pack('Na*', strlen($packet), $packet);
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if (strlen($packet) != fputs($this->fsock, $packet)) {
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user_error('Connection closed during signing');
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}
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$length = current(unpack('N', fread($this->fsock, 4)));
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$type = ord(fread($this->fsock, 1));
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if ($type != SYSTEM_SSH_AGENT_SIGN_RESPONSE) {
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user_error('Unable to retreive signature');
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}
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$signature_blob = fread($this->fsock, $length - 1);
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// the only other signature format defined - ssh-dss - is the same length as ssh-rsa
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// the + 12 is for the other various SSH added length fields
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return substr($signature_blob, strlen('ssh-rsa') + 12);
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}
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}
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/**
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* Pure-PHP ssh-agent client identity factory
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*
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* requestIdentities() method pumps out System_SSH_Agent_Identity objects
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*
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* @package System_SSH_Agent
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* @author Jim Wigginton <terrafrost@php.net>
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* @access internal
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*/
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class System_SSH_Agent
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{
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/**
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* Socket Resource
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*
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* @var Resource
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* @access private
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*/
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var $fsock;
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/**
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* Agent forwarding status
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*
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* @access private
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*/
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var $forward_status = SYSTEM_SSH_AGENT_FORWARD_NONE;
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/**
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* Buffer for accumulating forwarded authentication
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* agent data arriving on SSH data channel destined
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* for agent unix socket
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*
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* @access private
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*/
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var $socket_buffer = '';
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/**
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* Tracking the number of bytes we are expecting
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* to arrive for the agent socket on the SSH data
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* channel
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*/
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var $expected_bytes = 0;
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/**
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* Default Constructor
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*
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* @return System_SSH_Agent
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* @access public
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*/
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function System_SSH_Agent()
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{
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switch (true) {
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case isset($_SERVER['SSH_AUTH_SOCK']):
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$address = $_SERVER['SSH_AUTH_SOCK'];
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break;
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case isset($_ENV['SSH_AUTH_SOCK']):
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$address = $_ENV['SSH_AUTH_SOCK'];
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break;
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default:
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user_error('SSH_AUTH_SOCK not found');
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return false;
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}
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$this->fsock = fsockopen('unix://' . $address, 0, $errno, $errstr);
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if (!$this->fsock) {
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user_error("Unable to connect to ssh-agent (Error $errno: $errstr)");
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}
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}
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/**
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* Request Identities
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*
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* See "2.5.2 Requesting a list of protocol 2 keys"
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* Returns an array containing zero or more System_SSH_Agent_Identity objects
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*
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* @return Array
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* @access public
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*/
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function requestIdentities()
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{
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if (!$this->fsock) {
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return array();
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}
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$packet = pack('NC', 1, SYSTEM_SSH_AGENTC_REQUEST_IDENTITIES);
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if (strlen($packet) != fputs($this->fsock, $packet)) {
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user_error('Connection closed while requesting identities');
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}
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$length = current(unpack('N', fread($this->fsock, 4)));
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$type = ord(fread($this->fsock, 1));
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if ($type != SYSTEM_SSH_AGENT_IDENTITIES_ANSWER) {
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user_error('Unable to request identities');
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}
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$identities = array();
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$keyCount = current(unpack('N', fread($this->fsock, 4)));
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for ($i = 0; $i < $keyCount; $i++) {
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$length = current(unpack('N', fread($this->fsock, 4)));
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$key_blob = fread($this->fsock, $length);
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$length = current(unpack('N', fread($this->fsock, 4)));
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$key_comment = fread($this->fsock, $length);
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$length = current(unpack('N', substr($key_blob, 0, 4)));
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$key_type = substr($key_blob, 4, $length);
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switch ($key_type) {
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case 'ssh-rsa':
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if (!class_exists('Crypt_RSA')) {
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include_once 'Crypt/RSA.php';
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}
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$key = new Crypt_RSA();
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$key->loadKey('ssh-rsa ' . base64_encode($key_blob) . ' ' . $key_comment);
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break;
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case 'ssh-dss':
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// not currently supported
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break;
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}
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// resources are passed by reference by default
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if (isset($key)) {
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$identity = new System_SSH_Agent_Identity($this->fsock);
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$identity->setPublicKey($key);
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$identity->setPublicKeyBlob($key_blob);
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$identities[] = $identity;
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unset($key);
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}
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}
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return $identities;
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}
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/**
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* Signal that agent forwarding should
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* be requested when a channel is opened
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*
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* @param Net_SSH2 $ssh
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* @return Boolean
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* @access public
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*/
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function startSSHForwarding($ssh)
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{
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if ($this->forward_status == SYSTEM_SSH_AGENT_FORWARD_NONE) {
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$this->forward_status = SYSTEM_SSH_AGENT_FORWARD_REQUEST;
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}
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}
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/**
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* Request agent forwarding of remote server
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*
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* @param Net_SSH2 $ssh
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* @return Boolean
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* @access private
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*/
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function _request_forwarding($ssh)
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{
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$request_channel = $ssh->_get_open_channel();
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if ($request_channel === false) {
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return false;
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}
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$packet = pack(
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'CNNa*C',
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NET_SSH2_MSG_CHANNEL_REQUEST,
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$ssh->server_channels[$request_channel],
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strlen('auth-agent-req@openssh.com'),
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'auth-agent-req@openssh.com',
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1
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);
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$ssh->channel_status[$request_channel] = NET_SSH2_MSG_CHANNEL_REQUEST;
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if (!$ssh->_send_binary_packet($packet)) {
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return false;
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}
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$response = $ssh->_get_channel_packet($request_channel);
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if ($response === false) {
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return false;
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}
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$ssh->channel_status[$request_channel] = NET_SSH2_MSG_CHANNEL_OPEN;
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$this->forward_status = SYSTEM_SSH_AGENT_FORWARD_ACTIVE;
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return true;
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}
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/**
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* On successful channel open
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*
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* This method is called upon successful channel
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* open to give the SSH Agent an opportunity
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* to take further action. i.e. request agent forwarding
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*
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* @param Net_SSH2 $ssh
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* @access private
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*/
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function _on_channel_open($ssh)
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{
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if ($this->forward_status == SYSTEM_SSH_AGENT_FORWARD_REQUEST) {
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$this->_request_forwarding($ssh);
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}
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}
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/**
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* Forward data to SSH Agent and return data reply
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*
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* @param String $data
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* @return data from SSH Agent
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* @access private
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*/
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function _forward_data($data)
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{
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if ($this->expected_bytes > 0) {
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$this->socket_buffer.= $data;
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$this->expected_bytes -= strlen($data);
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} else {
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$agent_data_bytes = current(unpack('N', $data));
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$current_data_bytes = strlen($data);
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$this->socket_buffer = $data;
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if ($current_data_bytes != $agent_data_bytes + 4) {
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$this->expected_bytes = ($agent_data_bytes + 4) - $current_data_bytes;
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return false;
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}
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}
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if (strlen($this->socket_buffer) != fwrite($this->fsock, $this->socket_buffer)) {
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user_error('Connection closed attempting to forward data to SSH agent');
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}
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$this->socket_buffer = '';
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$this->expected_bytes = 0;
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$agent_reply_bytes = current(unpack('N', fread($this->fsock, 4)));
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$agent_reply_data = fread($this->fsock, $agent_reply_bytes);
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$agent_reply_data = current(unpack('a*', $agent_reply_data));
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return pack('Na*', $agent_reply_bytes, $agent_reply_data);
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}
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}
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