<?php
namespace Kant\Secure;

/* vim: set expandtab tabstop=4 shiftwidth=4 softtabstop=4: */

/**
 * Pure-PHP implementation of SSHv1.
 *
 * PHP versions 4 and 5
 *
 * Here's a short example of how to use this library:
 * <code>
 * <?php
 * include('Net/SSH1.php');
 *
 * $ssh = new Net_SSH1('www.domain.tld');
 * if (!$ssh->login('username', 'password')) {
 * exit('Login Failed');
 * }
 *
 * echo $ssh->exec('ls -la');
 * ?>
 * </code>
 *
 * Here's another short example:
 * <code>
 * <?php
 * include('Net/SSH1.php');
 *
 * $ssh = new Net_SSH1('www.domain.tld');
 * if (!$ssh->login('username', 'password')) {
 * exit('Login Failed');
 * }
 *
 * echo $ssh->read('username@username:~$');
 * $ssh->write("ls -la\n");
 * echo $ssh->read('username@username:~$');
 * ?>
 * </code>
 *
 * More information on the SSHv1 specification can be found by reading
 * {@link http://www.snailbook.com/docs/protocol-1.5.txt protocol-1.5.txt}.
 *
 * LICENSE: 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.
 *
 * @category Net
 * @package Net_SSH1
 * @author Jim Wigginton <terrafrost@php.net>
 * @copyright MMVII Jim Wigginton
 * @license http://www.opensource.org/licenses/mit-license.html MIT License
 * @version $Id: SSH1.php,v 1.15 2010/03/22 22:01:38 terrafrost Exp $
 * @link http://phpseclib.sourceforge.net
 */
/**
 * Include Math_BigInteger
 *
 * Used to do RSA encryption.
 */
if (!class_exists('Math_BigInteger')) {
    require_once ('Math/BigInteger.php');
}

/**
 * Include Crypt_Null
 */
// require_once('Crypt/Null.php');

/**
 * Include Crypt_DES
 */
if (!class_exists('Crypt_DES')) {
    require_once ('Crypt/DES.php');
}

/**
 * Include Crypt_TripleDES
 */
if (!class_exists('Crypt_TripleDES')) {
    require_once ('Crypt/TripleDES.php');
}

/**
 * Include Crypt_RC4
 */
if (!class_exists('Crypt_RC4')) {
    require_once ('Crypt/RC4.php');
}

/**
 * Include Crypt_Random
 */
// the class_exists() will only be called if the crypt_random_string function hasn't been defined and
// will trigger a call to __autoload() if you're wanting to auto-load classes
// call function_exists() a second time to stop the require_once from being called outside
// of the auto loader
if (!function_exists('crypt_random_string') && ! class_exists('Crypt_Random') && ! function_exists('crypt_random_string')) {
    require_once ('Crypt/Random.php');
}

/*
 * #@+
 * Encryption Methods
 *
 * @see Net_SSH1::getSupportedCiphers()
 * @access public
 */
/**
 * No encryption
 *
 * Not supported.
 */
define('NET_SSH1_CIPHER_NONE', 0);
/**
 * IDEA in CFB mode
 *
 * Not supported.
 */
define('NET_SSH1_CIPHER_IDEA', 1);
/**
 * DES in CBC mode
 */
define('NET_SSH1_CIPHER_DES', 2);
/**
 * Triple-DES in CBC mode
 *
 * All implementations are required to support this
 */
define('NET_SSH1_CIPHER_3DES', 3);
/**
 * TRI's Simple Stream encryption CBC
 *
 * Not supported nor is it defined in the official SSH1 specs. OpenSSH, however, does define it (see cipher.h),
 * although it doesn't use it (see cipher.c)
 */
define('NET_SSH1_CIPHER_BROKEN_TSS', 4);
/**
 * RC4
 *
 * Not supported.
 *
 * @internal According to the SSH1 specs:
 *          
 *           "The first 16 bytes of the session key are used as the key for
 *           the server to client direction. The remaining 16 bytes are used
 *           as the key for the client to server direction. This gives
 *           independent 128-bit keys for each direction."
 *          
 *           This library currently only supports encryption when the same key is being used for both directions. This is
 *           because there's only one $crypto object. Two could be added ($encrypt and $decrypt, perhaps).
 */
define('NET_SSH1_CIPHER_RC4', 5);
/**
 * Blowfish
 *
 * Not supported nor is it defined in the official SSH1 specs. OpenSSH, however, defines it (see cipher.h) and
 * uses it (see cipher.c)
 */
define('NET_SSH1_CIPHER_BLOWFISH', 6);
/* * #@- */

/*
 * #@+
 * Authentication Methods
 *
 * @see Net_SSH1::getSupportedAuthentications()
 * @access public
 */
/**
 * .rhosts or /etc/hosts.equiv
 */
define('NET_SSH1_AUTH_RHOSTS', 1);
/**
 * pure RSA authentication
 */
define('NET_SSH1_AUTH_RSA', 2);
/**
 * password authentication
 *
 * This is the only method that is supported by this library.
 */
define('NET_SSH1_AUTH_PASSWORD', 3);
/**
 * .rhosts with RSA host authentication
 */
define('NET_SSH1_AUTH_RHOSTS_RSA', 4);
/* * #@- */

/*
 * #@+
 * Terminal Modes
 *
 * @link http://3sp.com/content/developer/maverick-net/docs/Maverick.SSH.PseudoTerminalModesMembers.html
 * @access private
 */
define('NET_SSH1_TTY_OP_END', 0);
/* * #@- */

/**
 * The Response Type
 *
 * @see Net_SSH1::_get_binary_packet()
 * @access private
 */
define('NET_SSH1_RESPONSE_TYPE', 1);

/**
 * The Response Data
 *
 * @see Net_SSH1::_get_binary_packet()
 * @access private
 */
define('NET_SSH1_RESPONSE_DATA', 2);

/*
 * #@+
 * Execution Bitmap Masks
 *
 * @see Net_SSH1::bitmap
 * @access private
 */
define('NET_SSH1_MASK_CONSTRUCTOR', 0x00000001);
define('NET_SSH1_MASK_LOGIN', 0x00000002);
define('NET_SSH1_MASK_SHELL', 0x00000004);
/* * #@- */

/*
 * #@+
 * @access public
 * @see Net_SSH1::getLog()
 */
/**
 * Returns the message numbers
 */
define('NET_SSH1_LOG_SIMPLE', 1);
/**
 * Returns the message content
 */
define('NET_SSH1_LOG_COMPLEX', 2);
/**
 * Outputs the content real-time
 */
define('NET_SSH2_LOG_REALTIME', 3);
/**
 * Dumps the content real-time to a file
 */
define('NET_SSH2_LOG_REALTIME_FILE', 4);
/* * #@- */

/*
 * #@+
 * @access public
 * @see Net_SSH1::read()
 */
/**
 * Returns when a string matching $expect exactly is found
 */
define('NET_SSH1_READ_SIMPLE', 1);
/**
 * Returns when a string matching the regular expression $expect is found
 */
define('NET_SSH1_READ_REGEX', 2);

/* * #@- */

/**
 * Pure-PHP implementation of SSHv1.
 *
 * @author Jim Wigginton <terrafrost@php.net>
 * @version 0.1.0
 * @access public
 * @package Net_SSH1
 */
class Net_SSH1
{

    /**
     * The SSH identifier
     *
     * @var String
     * @access private
     */
    var $identifier = 'SSH-1.5-phpseclib';

    /**
     * The Socket Object
     *
     * @var Object
     * @access private
     */
    var $fsock;

    /**
     * The cryptography object
     *
     * @var Object
     * @access private
     */
    var $crypto = false;

    /**
     * Execution Bitmap
     *
     * The bits that are set represent functions that have been called already. This is used to determine
     * if a requisite function has been successfully executed. If not, an error should be thrown.
     *
     * @var Integer
     * @access private
     */
    var $bitmap = 0;

    /**
     * The Server Key Public Exponent
     *
     * Logged for debug purposes
     *
     * @see Net_SSH1::getServerKeyPublicExponent()
     * @var String
     * @access private
     */
    var $server_key_public_exponent;

    /**
     * The Server Key Public Modulus
     *
     * Logged for debug purposes
     *
     * @see Net_SSH1::getServerKeyPublicModulus()
     * @var String
     * @access private
     */
    var $server_key_public_modulus;

    /**
     * The Host Key Public Exponent
     *
     * Logged for debug purposes
     *
     * @see Net_SSH1::getHostKeyPublicExponent()
     * @var String
     * @access private
     */
    var $host_key_public_exponent;

    /**
     * The Host Key Public Modulus
     *
     * Logged for debug purposes
     *
     * @see Net_SSH1::getHostKeyPublicModulus()
     * @var String
     * @access private
     */
    var $host_key_public_modulus;

    /**
     * Supported Ciphers
     *
     * Logged for debug purposes
     *
     * @see Net_SSH1::getSupportedCiphers()
     * @var Array
     * @access private
     */
    var $supported_ciphers = array(
        NET_SSH1_CIPHER_NONE => 'No encryption',
        NET_SSH1_CIPHER_IDEA => 'IDEA in CFB mode',
        NET_SSH1_CIPHER_DES => 'DES in CBC mode',
        NET_SSH1_CIPHER_3DES => 'Triple-DES in CBC mode',
        NET_SSH1_CIPHER_BROKEN_TSS => 'TRI\'s Simple Stream encryption CBC',
        NET_SSH1_CIPHER_RC4 => 'RC4',
        NET_SSH1_CIPHER_BLOWFISH => 'Blowfish'
    );

    /**
     * Supported Authentications
     *
     * Logged for debug purposes
     *
     * @see Net_SSH1::getSupportedAuthentications()
     * @var Array
     * @access private
     */
    var $supported_authentications = array(
        NET_SSH1_AUTH_RHOSTS => '.rhosts or /etc/hosts.equiv',
        NET_SSH1_AUTH_RSA => 'pure RSA authentication',
        NET_SSH1_AUTH_PASSWORD => 'password authentication',
        NET_SSH1_AUTH_RHOSTS_RSA => '.rhosts with RSA host authentication'
    );

    /**
     * Server Identification
     *
     * @see Net_SSH1::getServerIdentification()
     * @var String
     * @access private
     */
    var $server_identification = '';

    /**
     * Protocol Flags
     *
     * @see Net_SSH1::Net_SSH1()
     * @var Array
     * @access private
     */
    var $protocol_flags = array();

    /**
     * Protocol Flag Log
     *
     * @see Net_SSH1::getLog()
     * @var Array
     * @access private
     */
    var $protocol_flag_log = array();

    /**
     * Message Log
     *
     * @see Net_SSH1::getLog()
     * @var Array
     * @access private
     */
    var $message_log = array();

    /**
     * Real-time log file pointer
     *
     * @see Net_SSH1::_append_log()
     * @var Resource
     * @access private
     */
    var $realtime_log_file;

    /**
     * Real-time log file size
     *
     * @see Net_SSH1::_append_log()
     * @var Integer
     * @access private
     */
    var $realtime_log_size;

    /**
     * Real-time log file wrap boolean
     *
     * @see Net_SSH1::_append_log()
     * @var Boolean
     * @access private
     */
    var $realtime_log_wrap;

    /**
     * Interactive Buffer
     *
     * @see Net_SSH1::read()
     * @var Array
     * @access private
     */
    var $interactiveBuffer = '';

    /**
     * Timeout
     *
     * @see Net_SSH1::setTimeout()
     * @access private
     */
    var $timeout;

    /**
     * Current Timeout
     *
     * @see Net_SSH2::_get_channel_packet()
     * @access private
     */
    var $curTimeout;

    /**
     * Default Constructor.
     *
     * Connects to an SSHv1 server
     *
     * @param String $host            
     * @param
     *            optional Integer $port
     * @param
     *            optional Integer $timeout
     * @param
     *            optional Integer $cipher
     * @return Net_SSH1
     * @access public
     */
    function Net_SSH1($host, $port = 22, $timeout = 10, $cipher = NET_SSH1_CIPHER_3DES)
    {
        $this->protocol_flags = array(
            1 => 'NET_SSH1_MSG_DISCONNECT',
            2 => 'NET_SSH1_SMSG_PUBLIC_KEY',
            3 => 'NET_SSH1_CMSG_SESSION_KEY',
            4 => 'NET_SSH1_CMSG_USER',
            9 => 'NET_SSH1_CMSG_AUTH_PASSWORD',
            10 => 'NET_SSH1_CMSG_REQUEST_PTY',
            12 => 'NET_SSH1_CMSG_EXEC_SHELL',
            13 => 'NET_SSH1_CMSG_EXEC_CMD',
            14 => 'NET_SSH1_SMSG_SUCCESS',
            15 => 'NET_SSH1_SMSG_FAILURE',
            16 => 'NET_SSH1_CMSG_STDIN_DATA',
            17 => 'NET_SSH1_SMSG_STDOUT_DATA',
            18 => 'NET_SSH1_SMSG_STDERR_DATA',
            19 => 'NET_SSH1_CMSG_EOF',
            20 => 'NET_SSH1_SMSG_EXITSTATUS',
            33 => 'NET_SSH1_CMSG_EXIT_CONFIRMATION'
        );
        
        $this->_define_array($this->protocol_flags);
        
        $this->fsock = @fsockopen($host, $port, $errno, $errstr, $timeout);
        if (!$this->fsock) {
            user_error(rtrim("Cannot connect to $host. Error $errno. $errstr"));
            return;
        }
        
        $this->server_identification = $init_line = fgets($this->fsock, 255);
        
        if (defined('NET_SSH1_LOGGING')) {
            $this->_append_log('<-', $this->server_identification);
            $this->_append_log('->', $this->identifier . "\r\n");
        }
        
        if (!preg_match('#SSH-([0-9\.]+)-(.+)#', $init_line, $parts)) {
            user_error('Can only connect to SSH servers');
            return;
        }
        if ($parts[1][0] != 1) {
            user_error("Cannot connect to SSH $parts[1] servers");
            return;
        }
        
        fputs($this->fsock, $this->identifier . "\r\n");
        
        $response = $this->_get_binary_packet();
        if ($response[NET_SSH1_RESPONSE_TYPE] != NET_SSH1_SMSG_PUBLIC_KEY) {
            user_error('Expected SSH_SMSG_PUBLIC_KEY');
            return;
        }
        
        $anti_spoofing_cookie = $this->_string_shift($response[NET_SSH1_RESPONSE_DATA], 8);
        
        $this->_string_shift($response[NET_SSH1_RESPONSE_DATA], 4);
        
        $temp = unpack('nlen', $this->_string_shift($response[NET_SSH1_RESPONSE_DATA], 2));
        $server_key_public_exponent = new Math_BigInteger($this->_string_shift($response[NET_SSH1_RESPONSE_DATA], ceil($temp['len'] / 8)), 256);
        $this->server_key_public_exponent = $server_key_public_exponent;
        
        $temp = unpack('nlen', $this->_string_shift($response[NET_SSH1_RESPONSE_DATA], 2));
        $server_key_public_modulus = new Math_BigInteger($this->_string_shift($response[NET_SSH1_RESPONSE_DATA], ceil($temp['len'] / 8)), 256);
        $this->server_key_public_modulus = $server_key_public_modulus;
        
        $this->_string_shift($response[NET_SSH1_RESPONSE_DATA], 4);
        
        $temp = unpack('nlen', $this->_string_shift($response[NET_SSH1_RESPONSE_DATA], 2));
        $host_key_public_exponent = new Math_BigInteger($this->_string_shift($response[NET_SSH1_RESPONSE_DATA], ceil($temp['len'] / 8)), 256);
        $this->host_key_public_exponent = $host_key_public_exponent;
        
        $temp = unpack('nlen', $this->_string_shift($response[NET_SSH1_RESPONSE_DATA], 2));
        $host_key_public_modulus = new Math_BigInteger($this->_string_shift($response[NET_SSH1_RESPONSE_DATA], ceil($temp['len'] / 8)), 256);
        $this->host_key_public_modulus = $host_key_public_modulus;
        
        $this->_string_shift($response[NET_SSH1_RESPONSE_DATA], 4);
        
        // get a list of the supported ciphers
        extract(unpack('Nsupported_ciphers_mask', $this->_string_shift($response[NET_SSH1_RESPONSE_DATA], 4)));
        foreach ($this->supported_ciphers as $mask => $name) {
            if (($supported_ciphers_mask & (1 << $mask)) == 0) {
                unset($this->supported_ciphers[$mask]);
            }
        }
        
        // get a list of the supported authentications
        extract(unpack('Nsupported_authentications_mask', $this->_string_shift($response[NET_SSH1_RESPONSE_DATA], 4)));
        foreach ($this->supported_authentications as $mask => $name) {
            if (($supported_authentications_mask & (1 << $mask)) == 0) {
                unset($this->supported_authentications[$mask]);
            }
        }
        
        $session_id = pack('H*', md5($host_key_public_modulus->toBytes() . $server_key_public_modulus->toBytes() . $anti_spoofing_cookie));
        
        $session_key = crypt_random_string(32);
        $double_encrypted_session_key = $session_key ^ str_pad($session_id, 32, chr(0));
        
        if ($server_key_public_modulus->compare($host_key_public_modulus) < 0) {
            $double_encrypted_session_key = $this->_rsa_crypt($double_encrypted_session_key, array(
                $server_key_public_exponent,
                $server_key_public_modulus
            ));
            $double_encrypted_session_key = $this->_rsa_crypt($double_encrypted_session_key, array(
                $host_key_public_exponent,
                $host_key_public_modulus
            ));
        } else {
            $double_encrypted_session_key = $this->_rsa_crypt($double_encrypted_session_key, array(
                $host_key_public_exponent,
                $host_key_public_modulus
            ));
            $double_encrypted_session_key = $this->_rsa_crypt($double_encrypted_session_key, array(
                $server_key_public_exponent,
                $server_key_public_modulus
            ));
        }
        
        $cipher = isset($this->supported_ciphers[$cipher]) ? $cipher : NET_SSH1_CIPHER_3DES;
        $data = pack('C2a*na*N', NET_SSH1_CMSG_SESSION_KEY, $cipher, $anti_spoofing_cookie, 8 * strlen($double_encrypted_session_key), $double_encrypted_session_key, 0);
        
        if (!$this->_send_binary_packet($data)) {
            user_error('Error sending SSH_CMSG_SESSION_KEY');
            return;
        }
        
        switch ($cipher) {
            // case NET_SSH1_CIPHER_NONE:
            // $this->crypto = new Crypt_Null();
            // break;
            case NET_SSH1_CIPHER_DES:
                $this->crypto = new Crypt_DES();
                $this->crypto->disablePadding();
                $this->crypto->enableContinuousBuffer();
                $this->crypto->setKey(substr($session_key, 0, 8));
                break;
            case NET_SSH1_CIPHER_3DES:
                $this->crypto = new Crypt_TripleDES(CRYPT_DES_MODE_3CBC);
                $this->crypto->disablePadding();
                $this->crypto->enableContinuousBuffer();
                $this->crypto->setKey(substr($session_key, 0, 24));
                break;
            // case NET_SSH1_CIPHER_RC4:
            // $this->crypto = new Crypt_RC4();
            // $this->crypto->enableContinuousBuffer();
            // $this->crypto->setKey(substr($session_key, 0, 16));
            // break;
        }
        
        $response = $this->_get_binary_packet();
        
        if ($response[NET_SSH1_RESPONSE_TYPE] != NET_SSH1_SMSG_SUCCESS) {
            user_error('Expected SSH_SMSG_SUCCESS');
            return;
        }
        
        $this->bitmap = NET_SSH1_MASK_CONSTRUCTOR;
    }

    /**
     * Login
     *
     * @param String $username            
     * @param
     *            optional String $password
     * @return Boolean
     * @access public
     */
    function login($username, $password = '')
    {
        if (!($this->bitmap & NET_SSH1_MASK_CONSTRUCTOR)) {
            return false;
        }
        
        $data = pack('CNa*', NET_SSH1_CMSG_USER, strlen($username), $username);
        
        if (!$this->_send_binary_packet($data)) {
            user_error('Error sending SSH_CMSG_USER');
            return false;
        }
        
        $response = $this->_get_binary_packet();
        
        if ($response === true) {
            return false;
        }
        if ($response[NET_SSH1_RESPONSE_TYPE] == NET_SSH1_SMSG_SUCCESS) {
            $this->bitmap |= NET_SSH1_MASK_LOGIN;
            return true;
        } else 
            if ($response[NET_SSH1_RESPONSE_TYPE] != NET_SSH1_SMSG_FAILURE) {
                user_error('Expected SSH_SMSG_SUCCESS or SSH_SMSG_FAILURE');
                return false;
            }
        
        $data = pack('CNa*', NET_SSH1_CMSG_AUTH_PASSWORD, strlen($password), $password);
        
        if (!$this->_send_binary_packet($data)) {
            user_error('Error sending SSH_CMSG_AUTH_PASSWORD');
            return false;
        }
        
        // remove the username and password from the last logged packet
        if (defined('NET_SSH1_LOGGING') && NET_SSH1_LOGGING == NET_SSH1_LOG_COMPLEX) {
            $data = pack('CNa*', NET_SSH1_CMSG_AUTH_PASSWORD, strlen('password'), 'password');
            $this->message_log[count($this->message_log) - 1] = $data;
        }
        
        $response = $this->_get_binary_packet();
        
        if ($response === true) {
            return false;
        }
        if ($response[NET_SSH1_RESPONSE_TYPE] == NET_SSH1_SMSG_SUCCESS) {
            $this->bitmap |= NET_SSH1_MASK_LOGIN;
            return true;
        } else 
            if ($response[NET_SSH1_RESPONSE_TYPE] == NET_SSH1_SMSG_FAILURE) {
                return false;
            } else {
                user_error('Expected SSH_SMSG_SUCCESS or SSH_SMSG_FAILURE');
                return false;
            }
    }

    /**
     * Set Timeout
     *
     * $ssh->exec('ping 127.0.0.1'); on a Linux host will never return and will run indefinitely. setTimeout() makes it so it'll timeout.
     * Setting $timeout to false or 0 will mean there is no timeout.
     *
     * @param Mixed $timeout            
     */
    function setTimeout($timeout)
    {
        $this->timeout = $this->curTimeout = $timeout;
    }

    /**
     * Executes a command on a non-interactive shell, returns the output, and quits.
     *
     * An SSH1 server will close the connection after a command has been executed on a non-interactive shell. SSH2
     * servers don't, however, this isn't an SSH2 client. The way this works, on the server, is by initiating a
     * shell with the -s option, as discussed in the following links:
     *
     * {@link http://www.faqs.org/docs/bashman/bashref_65.html http://www.faqs.org/docs/bashman/bashref_65.html}
     * {@link http://www.faqs.org/docs/bashman/bashref_62.html http://www.faqs.org/docs/bashman/bashref_62.html}
     *
     * To execute further commands, a new Net_SSH1 object will need to be created.
     *
     * Returns false on failure and the output, otherwise.
     *
     * @see Net_SSH1::interactiveRead()
     * @see Net_SSH1::interactiveWrite()
     * @param String $cmd            
     * @return mixed
     * @access public
     */
    function exec($cmd, $block = true)
    {
        if (!($this->bitmap & NET_SSH1_MASK_LOGIN)) {
            user_error('Operation disallowed prior to login()');
            return false;
        }
        
        $data = pack('CNa*', NET_SSH1_CMSG_EXEC_CMD, strlen($cmd), $cmd);
        
        if (!$this->_send_binary_packet($data)) {
            user_error('Error sending SSH_CMSG_EXEC_CMD');
            return false;
        }
        
        if (!$block) {
            return true;
        }
        
        $output = '';
        $response = $this->_get_binary_packet();
        
        if ($response !== false) {
            do {
                $output .= substr($response[NET_SSH1_RESPONSE_DATA], 4);
                $response = $this->_get_binary_packet();
            } while (is_array($response) && $response[NET_SSH1_RESPONSE_TYPE] != NET_SSH1_SMSG_EXITSTATUS);
        }
        
        $data = pack('C', NET_SSH1_CMSG_EXIT_CONFIRMATION);
        
        // i don't think it's really all that important if this packet gets sent or not.
        $this->_send_binary_packet($data);
        
        fclose($this->fsock);
        
        // reset the execution bitmap - a new Net_SSH1 object needs to be created.
        $this->bitmap = 0;
        
        return $output;
    }

    /**
     * Creates an interactive shell
     *
     * @see Net_SSH1::interactiveRead()
     * @see Net_SSH1::interactiveWrite()
     * @return Boolean
     * @access private
     */
    function _initShell()
    {
        // connect using the sample parameters in protocol-1.5.txt.
        // according to wikipedia.org's entry on text terminals, "the fundamental type of application running on a text
        // terminal is a command line interpreter or shell". thus, opening a terminal session to run the shell.
        $data = pack('CNa*N4C', NET_SSH1_CMSG_REQUEST_PTY, strlen('vt100'), 'vt100', 24, 80, 0, 0, NET_SSH1_TTY_OP_END);
        
        if (!$this->_send_binary_packet($data)) {
            user_error('Error sending SSH_CMSG_REQUEST_PTY');
            return false;
        }
        
        $response = $this->_get_binary_packet();
        
        if ($response === true) {
            return false;
        }
        if ($response[NET_SSH1_RESPONSE_TYPE] != NET_SSH1_SMSG_SUCCESS) {
            user_error('Expected SSH_SMSG_SUCCESS');
            return false;
        }
        
        $data = pack('C', NET_SSH1_CMSG_EXEC_SHELL);
        
        if (!$this->_send_binary_packet($data)) {
            user_error('Error sending SSH_CMSG_EXEC_SHELL');
            return false;
        }
        
        $this->bitmap |= NET_SSH1_MASK_SHELL;
        
        // stream_set_blocking($this->fsock, 0);
        
        return true;
    }

    /**
     * Inputs a command into an interactive shell.
     *
     * @see Net_SSH1::interactiveWrite()
     * @param String $cmd            
     * @return Boolean
     * @access public
     */
    function write($cmd)
    {
        return $this->interactiveWrite($cmd);
    }

    /**
     * Returns the output of an interactive shell when there's a match for $expect
     *
     * $expect can take the form of a string literal or, if $mode == NET_SSH1_READ_REGEX,
     * a regular expression.
     *
     * @see Net_SSH1::write()
     * @param String $expect            
     * @param Integer $mode            
     * @return Boolean
     * @access public
     */
    function read($expect, $mode = NET_SSH1_READ_SIMPLE)
    {
        if (!($this->bitmap & NET_SSH1_MASK_LOGIN)) {
            user_error('Operation disallowed prior to login()');
            return false;
        }
        
        if (!($this->bitmap & NET_SSH1_MASK_SHELL) && ! $this->_initShell()) {
            user_error('Unable to initiate an interactive shell session');
            return false;
        }
        
        $match = $expect;
        while (true) {
            if ($mode == NET_SSH1_READ_REGEX) {
                preg_match($expect, $this->interactiveBuffer, $matches);
                $match = isset($matches[0]) ? $matches[0] : '';
            }
            $pos = strlen($match) ? strpos($this->interactiveBuffer, $match) : false;
            if ($pos !== false) {
                return $this->_string_shift($this->interactiveBuffer, $pos + strlen($match));
            }
            $response = $this->_get_binary_packet();
            
            if ($response === true) {
                return $this->_string_shift($this->interactiveBuffer, strlen($this->interactiveBuffer));
            }
            $this->interactiveBuffer .= substr($response[NET_SSH1_RESPONSE_DATA], 4);
        }
    }

    /**
     * Inputs a command into an interactive shell.
     *
     * @see Net_SSH1::interactiveRead()
     * @param String $cmd            
     * @return Boolean
     * @access public
     */
    function interactiveWrite($cmd)
    {
        if (!($this->bitmap & NET_SSH1_MASK_LOGIN)) {
            user_error('Operation disallowed prior to login()');
            return false;
        }
        
        if (!($this->bitmap & NET_SSH1_MASK_SHELL) && ! $this->_initShell()) {
            user_error('Unable to initiate an interactive shell session');
            return false;
        }
        
        $data = pack('CNa*', NET_SSH1_CMSG_STDIN_DATA, strlen($cmd), $cmd);
        
        if (!$this->_send_binary_packet($data)) {
            user_error('Error sending SSH_CMSG_STDIN');
            return false;
        }
        
        return true;
    }

    /**
     * Returns the output of an interactive shell when no more output is available.
     *
     * Requires PHP 4.3.0 or later due to the use of the stream_select() function. If you see stuff like
     * "^[[00m", you're seeing ANSI escape codes. According to
     * {@link http://support.microsoft.com/kb/101875 How to Enable ANSI.SYS in a Command Window}, "Windows NT
     * does not support ANSI escape sequences in Win32 Console applications", so if you're a Windows user,
     * there's not going to be much recourse.
     *
     * @see Net_SSH1::interactiveRead()
     * @return String
     * @access public
     */
    function interactiveRead()
    {
        if (!($this->bitmap & NET_SSH1_MASK_LOGIN)) {
            user_error('Operation disallowed prior to login()');
            return false;
        }
        
        if (!($this->bitmap & NET_SSH1_MASK_SHELL) && ! $this->_initShell()) {
            user_error('Unable to initiate an interactive shell session');
            return false;
        }
        
        $read = array(
            $this->fsock
        );
        $write = $except = null;
        if (stream_select($read, $write, $except, 0)) {
            $response = $this->_get_binary_packet();
            return substr($response[NET_SSH1_RESPONSE_DATA], 4);
        } else {
            return '';
        }
    }

    /**
     * Disconnect
     *
     * @access public
     */
    function disconnect()
    {
        $this->_disconnect();
    }

    /**
     * Destructor.
     *
     * Will be called, automatically, if you're supporting just PHP5. If you're supporting PHP4, you'll need to call
     * disconnect().
     *
     * @access public
     */
    function __destruct()
    {
        $this->_disconnect();
    }

    /**
     * Disconnect
     *
     * @param String $msg            
     * @access private
     */
    function _disconnect($msg = 'Client Quit')
    {
        if ($this->bitmap) {
            $data = pack('C', NET_SSH1_CMSG_EOF);
            $this->_send_binary_packet($data);
            /*
             * $response = $this->_get_binary_packet();
             * if ($response === true) {
             * $response = array(NET_SSH1_RESPONSE_TYPE => -1);
             * }
             * switch ($response[NET_SSH1_RESPONSE_TYPE]) {
             * case NET_SSH1_SMSG_EXITSTATUS:
             * $data = pack('C', NET_SSH1_CMSG_EXIT_CONFIRMATION);
             * break;
             * default:
             * $data = pack('CNa*', NET_SSH1_MSG_DISCONNECT, strlen($msg), $msg);
             * }
             */
            $data = pack('CNa*', NET_SSH1_MSG_DISCONNECT, strlen($msg), $msg);
            
            $this->_send_binary_packet($data);
            fclose($this->fsock);
            $this->bitmap = 0;
        }
    }

    /**
     * Gets Binary Packets
     *
     * See 'The Binary Packet Protocol' of protocol-1.5.txt for more info.
     *
     * Also, this function could be improved upon by adding detection for the following exploit:
     * http://www.securiteam.com/securitynews/5LP042K3FY.html
     *
     * @see Net_SSH1::_send_binary_packet()
     * @return Array
     * @access private
     */
    function _get_binary_packet()
    {
        if (feof($this->fsock)) {
            // user_error('connection closed prematurely');
            return false;
        }
        
        if ($this->curTimeout) {
            $read = array(
                $this->fsock
            );
            $write = $except = NULL;
            
            $start = strtok(microtime(), ' ') + strtok(''); // http://php.net/microtime#61838
            $sec = floor($this->curTimeout);
            $usec = 1000000 * ($this->curTimeout - $sec);
            // on windows this returns a "Warning: Invalid CRT parameters detected" error
            if (!@stream_select($read, $write, $except, $sec, $usec) && ! count($read)) {
                // $this->_disconnect('Timeout');
                return true;
            }
            $elapsed = strtok(microtime(), ' ') + strtok('') - $start;
            $this->curTimeout -= $elapsed;
        }
        
        $start = strtok(microtime(), ' ') + strtok(''); // http://php.net/microtime#61838
        $temp = unpack('Nlength', fread($this->fsock, 4));
        
        $padding_length = 8 - ($temp['length'] & 7);
        $length = $temp['length'] + $padding_length;
        
        while ($length > 0) {
            $temp = fread($this->fsock, $length);
            $raw .= $temp;
            $length -= strlen($temp);
        }
        $stop = strtok(microtime(), ' ') + strtok('');
        
        if (strlen($raw) && $this->crypto !== false) {
            $raw = $this->crypto->decrypt($raw);
        }
        
        $padding = substr($raw, 0, $padding_length);
        $type = $raw[$padding_length];
        $data = substr($raw, $padding_length + 1, - 4);
        
        $temp = unpack('Ncrc', substr($raw, - 4));
        
        // if ( $temp['crc'] != $this->_crc($padding . $type . $data) ) {
        // user_error('Bad CRC in packet from server');
        // return false;
        // }
        
        $type = ord($type);
        
        if (defined('NET_SSH1_LOGGING')) {
            $temp = isset($this->protocol_flags[$type]) ? $this->protocol_flags[$type] : 'UNKNOWN';
            $temp = '<- ' . $temp . ' (' . round($stop - $start, 4) . 's)';
            $this->_append_log($temp, $data);
        }
        
        return array(
            NET_SSH1_RESPONSE_TYPE => $type,
            NET_SSH1_RESPONSE_DATA => $data
        );
    }

    /**
     * Sends Binary Packets
     *
     * Returns true on success, false on failure.
     *
     * @see Net_SSH1::_get_binary_packet()
     * @param String $data            
     * @return Boolean
     * @access private
     */
    function _send_binary_packet($data)
    {
        if (feof($this->fsock)) {
            // user_error('connection closed prematurely');
            return false;
        }
        
        $length = strlen($data) + 4;
        
        $padding = crypt_random_string(8 - ($length & 7));
        
        $orig = $data;
        $data = $padding . $data;
        $data .= pack('N', $this->_crc($data));
        
        if ($this->crypto !== false) {
            $data = $this->crypto->encrypt($data);
        }
        
        $packet = pack('Na*', $length, $data);
        
        $start = strtok(microtime(), ' ') + strtok(''); // http://php.net/microtime#61838
        $result = strlen($packet) == fputs($this->fsock, $packet);
        $stop = strtok(microtime(), ' ') + strtok('');
        
        if (defined('NET_SSH1_LOGGING')) {
            $temp = isset($this->protocol_flags[ord($orig[0])]) ? $this->protocol_flags[ord($orig[0])] : 'UNKNOWN';
            $temp = '-> ' . $temp . ' (' . round($stop - $start, 4) . 's)';
            $this->_append_log($temp, $orig);
        }
        
        return $result;
    }

    /**
     * Cyclic Redundancy Check (CRC)
     *
     * PHP's crc32 function is implemented slightly differently than the one that SSH v1 uses, so
     * we've reimplemented it. A more detailed discussion of the differences can be found after
     * $crc_lookup_table's initialization.
     *
     * @see Net_SSH1::_get_binary_packet()
     * @see Net_SSH1::_send_binary_packet()
     * @param String $data            
     * @return Integer
     * @access private
     */
    function _crc($data)
    {
        static $crc_lookup_table = array(
            0x00000000,
            0x77073096,
            0xEE0E612C,
            0x990951BA,
            0x076DC419,
            0x706AF48F,
            0xE963A535,
            0x9E6495A3,
            0x0EDB8832,
            0x79DCB8A4,
            0xE0D5E91E,
            0x97D2D988,
            0x09B64C2B,
            0x7EB17CBD,
            0xE7B82D07,
            0x90BF1D91,
            0x1DB71064,
            0x6AB020F2,
            0xF3B97148,
            0x84BE41DE,
            0x1ADAD47D,
            0x6DDDE4EB,
            0xF4D4B551,
            0x83D385C7,
            0x136C9856,
            0x646BA8C0,
            0xFD62F97A,
            0x8A65C9EC,
            0x14015C4F,
            0x63066CD9,
            0xFA0F3D63,
            0x8D080DF5,
            0x3B6E20C8,
            0x4C69105E,
            0xD56041E4,
            0xA2677172,
            0x3C03E4D1,
            0x4B04D447,
            0xD20D85FD,
            0xA50AB56B,
            0x35B5A8FA,
            0x42B2986C,
            0xDBBBC9D6,
            0xACBCF940,
            0x32D86CE3,
            0x45DF5C75,
            0xDCD60DCF,
            0xABD13D59,
            0x26D930AC,
            0x51DE003A,
            0xC8D75180,
            0xBFD06116,
            0x21B4F4B5,
            0x56B3C423,
            0xCFBA9599,
            0xB8BDA50F,
            0x2802B89E,
            0x5F058808,
            0xC60CD9B2,
            0xB10BE924,
            0x2F6F7C87,
            0x58684C11,
            0xC1611DAB,
            0xB6662D3D,
            0x76DC4190,
            0x01DB7106,
            0x98D220BC,
            0xEFD5102A,
            0x71B18589,
            0x06B6B51F,
            0x9FBFE4A5,
            0xE8B8D433,
            0x7807C9A2,
            0x0F00F934,
            0x9609A88E,
            0xE10E9818,
            0x7F6A0DBB,
            0x086D3D2D,
            0x91646C97,
            0xE6635C01,
            0x6B6B51F4,
            0x1C6C6162,
            0x856530D8,
            0xF262004E,
            0x6C0695ED,
            0x1B01A57B,
            0x8208F4C1,
            0xF50FC457,
            0x65B0D9C6,
            0x12B7E950,
            0x8BBEB8EA,
            0xFCB9887C,
            0x62DD1DDF,
            0x15DA2D49,
            0x8CD37CF3,
            0xFBD44C65,
            0x4DB26158,
            0x3AB551CE,
            0xA3BC0074,
            0xD4BB30E2,
            0x4ADFA541,
            0x3DD895D7,
            0xA4D1C46D,
            0xD3D6F4FB,
            0x4369E96A,
            0x346ED9FC,
            0xAD678846,
            0xDA60B8D0,
            0x44042D73,
            0x33031DE5,
            0xAA0A4C5F,
            0xDD0D7CC9,
            0x5005713C,
            0x270241AA,
            0xBE0B1010,
            0xC90C2086,
            0x5768B525,
            0x206F85B3,
            0xB966D409,
            0xCE61E49F,
            0x5EDEF90E,
            0x29D9C998,
            0xB0D09822,
            0xC7D7A8B4,
            0x59B33D17,
            0x2EB40D81,
            0xB7BD5C3B,
            0xC0BA6CAD,
            0xEDB88320,
            0x9ABFB3B6,
            0x03B6E20C,
            0x74B1D29A,
            0xEAD54739,
            0x9DD277AF,
            0x04DB2615,
            0x73DC1683,
            0xE3630B12,
            0x94643B84,
            0x0D6D6A3E,
            0x7A6A5AA8,
            0xE40ECF0B,
            0x9309FF9D,
            0x0A00AE27,
            0x7D079EB1,
            0xF00F9344,
            0x8708A3D2,
            0x1E01F268,
            0x6906C2FE,
            0xF762575D,
            0x806567CB,
            0x196C3671,
            0x6E6B06E7,
            0xFED41B76,
            0x89D32BE0,
            0x10DA7A5A,
            0x67DD4ACC,
            0xF9B9DF6F,
            0x8EBEEFF9,
            0x17B7BE43,
            0x60B08ED5,
            0xD6D6A3E8,
            0xA1D1937E,
            0x38D8C2C4,
            0x4FDFF252,
            0xD1BB67F1,
            0xA6BC5767,
            0x3FB506DD,
            0x48B2364B,
            0xD80D2BDA,
            0xAF0A1B4C,
            0x36034AF6,
            0x41047A60,
            0xDF60EFC3,
            0xA867DF55,
            0x316E8EEF,
            0x4669BE79,
            0xCB61B38C,
            0xBC66831A,
            0x256FD2A0,
            0x5268E236,
            0xCC0C7795,
            0xBB0B4703,
            0x220216B9,
            0x5505262F,
            0xC5BA3BBE,
            0xB2BD0B28,
            0x2BB45A92,
            0x5CB36A04,
            0xC2D7FFA7,
            0xB5D0CF31,
            0x2CD99E8B,
            0x5BDEAE1D,
            0x9B64C2B0,
            0xEC63F226,
            0x756AA39C,
            0x026D930A,
            0x9C0906A9,
            0xEB0E363F,
            0x72076785,
            0x05005713,
            0x95BF4A82,
            0xE2B87A14,
            0x7BB12BAE,
            0x0CB61B38,
            0x92D28E9B,
            0xE5D5BE0D,
            0x7CDCEFB7,
            0x0BDBDF21,
            0x86D3D2D4,
            0xF1D4E242,
            0x68DDB3F8,
            0x1FDA836E,
            0x81BE16CD,
            0xF6B9265B,
            0x6FB077E1,
            0x18B74777,
            0x88085AE6,
            0xFF0F6A70,
            0x66063BCA,
            0x11010B5C,
            0x8F659EFF,
            0xF862AE69,
            0x616BFFD3,
            0x166CCF45,
            0xA00AE278,
            0xD70DD2EE,
            0x4E048354,
            0x3903B3C2,
            0xA7672661,
            0xD06016F7,
            0x4969474D,
            0x3E6E77DB,
            0xAED16A4A,
            0xD9D65ADC,
            0x40DF0B66,
            0x37D83BF0,
            0xA9BCAE53,
            0xDEBB9EC5,
            0x47B2CF7F,
            0x30B5FFE9,
            0xBDBDF21C,
            0xCABAC28A,
            0x53B39330,
            0x24B4A3A6,
            0xBAD03605,
            0xCDD70693,
            0x54DE5729,
            0x23D967BF,
            0xB3667A2E,
            0xC4614AB8,
            0x5D681B02,
            0x2A6F2B94,
            0xB40BBE37,
            0xC30C8EA1,
            0x5A05DF1B,
            0x2D02EF8D
        );
        
        // For this function to yield the same output as PHP's crc32 function, $crc would have to be
        // set to 0xFFFFFFFF, initially - not 0x00000000 as it currently is.
        $crc = 0x00000000;
        $length = strlen($data);
        
        for ($i = 0; $i < $length; $i ++) {
            // We AND $crc >> 8 with 0x00FFFFFF because we want the eight newly added bits to all
            // be zero. PHP, unfortunately, doesn't always do this. 0x80000000 >> 8, as an example,
            // yields 0xFF800000 - not 0x00800000. The following link elaborates:
            // http://www.php.net/manual/en/language.operators.bitwise.php#57281
            $crc = (($crc >> 8) & 0x00FFFFFF) ^ $crc_lookup_table[($crc & 0xFF) ^ ord($data[$i])];
        }
        
        // In addition to having to set $crc to 0xFFFFFFFF, initially, the return value must be XOR'd with
        // 0xFFFFFFFF for this function to return the same thing that PHP's crc32 function would.
        return $crc;
    }

    /**
     * String Shift
     *
     * Inspired by array_shift
     *
     * @param String $string            
     * @param
     *            optional Integer $index
     * @return String
     * @access private
     */
    function _string_shift(&$string, $index = 1)
    {
        $substr = substr($string, 0, $index);
        $string = substr($string, $index);
        return $substr;
    }

    /**
     * RSA Encrypt
     *
     * Returns mod(pow($m, $e), $n), where $n should be the product of two (large) primes $p and $q and where $e
     * should be a number with the property that gcd($e, ($p - 1) * ($q - 1)) == 1. Could just make anything that
     * calls this call modexp, instead, but I think this makes things clearer, maybe...
     *
     * @see Net_SSH1::Net_SSH1()
     * @param Math_BigInteger $m            
     * @param Array $key            
     * @return Math_BigInteger
     * @access private
     */
    function _rsa_crypt($m, $key)
    {
        /*
         * if (!class_exists('Crypt_RSA')) {
         * require_once('Crypt/RSA.php');
         * }
         *
         * $rsa = new Crypt_RSA();
         * $rsa->loadKey($key, CRYPT_RSA_PUBLIC_FORMAT_RAW);
         * $rsa->setEncryptionMode(CRYPT_RSA_ENCRYPTION_PKCS1);
         * return $rsa->encrypt($m);
         */
        
        // To quote from protocol-1.5.txt:
        // The most significant byte (which is only partial as the value must be
        // less than the public modulus, which is never a power of two) is zero.
        //
        // The next byte contains the value 2 (which stands for public-key
        // encrypted data in the PKCS standard [PKCS#1]). Then, there are non-
        // zero random bytes to fill any unused space, a zero byte, and the data
        // to be encrypted in the least significant bytes, the last byte of the
        // data in the least significant byte.
        // Presumably the part of PKCS#1 they're refering to is "Section 7.2.1 Encryption Operation",
        // under "7.2 RSAES-PKCS1-v1.5" and "7 Encryption schemes" of the following URL:
        // ftp://ftp.rsasecurity.com/pub/pkcs/pkcs-1/pkcs-1v2-1.pdf
        $modulus = $key[1]->toBytes();
        $length = strlen($modulus) - strlen($m) - 3;
        $random = '';
        while (strlen($random) != $length) {
            $block = crypt_random_string($length - strlen($random));
            $block = str_replace("\x00", '', $block);
            $random .= $block;
        }
        $temp = chr(0) . chr(2) . $random . chr(0) . $m;
        
        $m = new Math_BigInteger($temp, 256);
        $m = $m->modPow($key[0], $key[1]);
        
        return $m->toBytes();
    }

    /**
     * Define Array
     *
     * Takes any number of arrays whose indices are integers and whose values are strings and defines a bunch of
     * named constants from it, using the value as the name of the constant and the index as the value of the constant.
     * If any of the constants that would be defined already exists, none of the constants will be defined.
     *
     * @param Array $array            
     * @access private
     */
    function _define_array()
    {
        $args = func_get_args();
        foreach ($args as $arg) {
            foreach ($arg as $key => $value) {
                if (!defined($value)) {
                    define($value, $key);
                } else {
                    break 2;
                }
            }
        }
    }

    /**
     * Returns a log of the packets that have been sent and received.
     *
     * Returns a string if NET_SSH2_LOGGING == NET_SSH2_LOG_COMPLEX, an array if NET_SSH2_LOGGING == NET_SSH2_LOG_SIMPLE and false if !defined('NET_SSH2_LOGGING')
     *
     * @access public
     * @return String or Array
     */
    function getLog()
    {
        if (!defined('NET_SSH1_LOGGING')) {
            return false;
        }
        
        switch (NET_SSH1_LOGGING) {
            case NET_SSH1_LOG_SIMPLE:
                return $this->message_number_log;
                break;
            case NET_SSH1_LOG_COMPLEX:
                return $this->_format_log($this->message_log, $this->protocol_flags_log);
                break;
            default:
                return false;
        }
    }

    /**
     * Formats a log for printing
     *
     * @param Array $message_log            
     * @param Array $message_number_log            
     * @access private
     * @return String
     */
    function _format_log($message_log, $message_number_log)
    {
        static $boundary = ':', $long_width = 65, $short_width = 16;
        
        $output = '';
        for ($i = 0; $i < count($message_log); $i ++) {
            $output .= $message_number_log[$i] . "\r\n";
            $current_log = $message_log[$i];
            $j = 0;
            do {
                if (strlen($current_log)) {
                    $output .= str_pad(dechex($j), 7, '0', STR_PAD_LEFT) . '0  ';
                }
                $fragment = $this->_string_shift($current_log, $short_width);
                $hex = substr(preg_replace('#(.)#es', '"' . $boundary . '" . str_pad(dechex(ord(substr("\\1", -1))), 2, "0", STR_PAD_LEFT)', $fragment), strlen($boundary));
                // replace non ASCII printable characters with dots
                // http://en.wikipedia.org/wiki/ASCII#ASCII_printable_characters
                // also replace < with a . since < messes up the output on web browsers
                $raw = preg_replace('#[^\x20-\x7E]|<#', '.', $fragment);
                $output .= str_pad($hex, $long_width - $short_width, ' ') . $raw . "\r\n";
                $j ++;
            } while (strlen($current_log));
            $output .= "\r\n";
        }
        
        return $output;
    }

    /**
     * Return the server key public exponent
     *
     * Returns, by default, the base-10 representation. If $raw_output is set to true, returns, instead,
     * the raw bytes. This behavior is similar to PHP's md5() function.
     *
     * @param
     *            optional Boolean $raw_output
     * @return String
     * @access public
     */
    function getServerKeyPublicExponent($raw_output = false)
    {
        return $raw_output ? $this->server_key_public_exponent->toBytes() : $this->server_key_public_exponent->toString();
    }

    /**
     * Return the server key public modulus
     *
     * Returns, by default, the base-10 representation. If $raw_output is set to true, returns, instead,
     * the raw bytes. This behavior is similar to PHP's md5() function.
     *
     * @param
     *            optional Boolean $raw_output
     * @return String
     * @access public
     */
    function getServerKeyPublicModulus($raw_output = false)
    {
        return $raw_output ? $this->server_key_public_modulus->toBytes() : $this->server_key_public_modulus->toString();
    }

    /**
     * Return the host key public exponent
     *
     * Returns, by default, the base-10 representation. If $raw_output is set to true, returns, instead,
     * the raw bytes. This behavior is similar to PHP's md5() function.
     *
     * @param
     *            optional Boolean $raw_output
     * @return String
     * @access public
     */
    function getHostKeyPublicExponent($raw_output = false)
    {
        return $raw_output ? $this->host_key_public_exponent->toBytes() : $this->host_key_public_exponent->toString();
    }

    /**
     * Return the host key public modulus
     *
     * Returns, by default, the base-10 representation. If $raw_output is set to true, returns, instead,
     * the raw bytes. This behavior is similar to PHP's md5() function.
     *
     * @param
     *            optional Boolean $raw_output
     * @return String
     * @access public
     */
    function getHostKeyPublicModulus($raw_output = false)
    {
        return $raw_output ? $this->host_key_public_modulus->toBytes() : $this->host_key_public_modulus->toString();
    }

    /**
     * Return a list of ciphers supported by SSH1 server.
     *
     * Just because a cipher is supported by an SSH1 server doesn't mean it's supported by this library. If $raw_output
     * is set to true, returns, instead, an array of constants. ie. instead of array('Triple-DES in CBC mode'), you'll
     * get array(NET_SSH1_CIPHER_3DES).
     *
     * @param
     *            optional Boolean $raw_output
     * @return Array
     * @access public
     */
    function getSupportedCiphers($raw_output = false)
    {
        return $raw_output ? array_keys($this->supported_ciphers) : array_values($this->supported_ciphers);
    }

    /**
     * Return a list of authentications supported by SSH1 server.
     *
     * Just because a cipher is supported by an SSH1 server doesn't mean it's supported by this library. If $raw_output
     * is set to true, returns, instead, an array of constants. ie. instead of array('password authentication'), you'll
     * get array(NET_SSH1_AUTH_PASSWORD).
     *
     * @param
     *            optional Boolean $raw_output
     * @return Array
     * @access public
     */
    function getSupportedAuthentications($raw_output = false)
    {
        return $raw_output ? array_keys($this->supported_authentications) : array_values($this->supported_authentications);
    }

    /**
     * Return the server identification.
     *
     * @return String
     * @access public
     */
    function getServerIdentification()
    {
        return rtrim($this->server_identification);
    }

    /**
     * Logs data packets
     *
     * Makes sure that only the last 1MB worth of packets will be logged
     *
     * @param String $data            
     * @access private
     */
    function _append_log($protocol_flags, $message)
    {
        switch (NET_SSH1_LOGGING) {
            // useful for benchmarks
            case NET_SSH1_LOG_SIMPLE:
                $this->protocol_flags_log[] = $protocol_flags;
                break;
            // the most useful log for SSH1
            case NET_SSH1_LOG_COMPLEX:
                $this->protocol_flags_log[] = $protocol_flags;
                $this->_string_shift($message);
                $this->log_size += strlen($message);
                $this->message_log[] = $message;
                while ($this->log_size > NET_SSH2_LOG_MAX_SIZE) {
                    $this->log_size -= strlen(array_shift($this->message_log));
                    array_shift($this->protocol_flags_log);
                }
                break;
            // dump the output out realtime; packets may be interspersed with non packets,
            // passwords won't be filtered out and select other packets may not be correctly
            // identified
            case NET_SSH1_LOG_REALTIME:
                echo "<pre>\r\n" . $this->_format_log(array(
                    $message
                ), array(
                    $protocol_flags
                )) . "\r\n</pre>\r\n";
                @flush();
                @ob_flush();
                break;
            // basically the same thing as NET_SSH1_LOG_REALTIME with the caveat that NET_SSH1_LOG_REALTIME_FILE
            // needs to be defined and that the resultant log file will be capped out at NET_SSH1_LOG_MAX_SIZE.
            // the earliest part of the log file is denoted by the first <<< START >>> and is not going to necessarily
            // at the beginning of the file
            case NET_SSH1_LOG_REALTIME_FILE:
                if (!isset($this->realtime_log_file)) {
                    // PHP doesn't seem to like using constants in fopen()
                    $filename = NET_SSH2_LOG_REALTIME_FILE;
                    $fp = fopen($filename, 'w');
                    $this->realtime_log_file = $fp;
                }
                if (!is_resource($this->realtime_log_file)) {
                    break;
                }
                $entry = $this->_format_log(array(
                    $message
                ), array(
                    $protocol_flags
                ));
                if ($this->realtime_log_wrap) {
                    $temp = "<<< START >>>\r\n";
                    $entry .= $temp;
                    fseek($this->realtime_log_file, ftell($this->realtime_log_file) - strlen($temp));
                }
                $this->realtime_log_size += strlen($entry);
                if ($this->realtime_log_size > NET_SSH1_LOG_MAX_SIZE) {
                    fseek($this->realtime_log_file, 0);
                    $this->realtime_log_size = strlen($entry);
                    $this->realtime_log_wrap = true;
                }
                fputs($this->realtime_log_file, $entry);
        }
    }
}
