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SSH2: add support for zlib and zlib@openssh.com compression

This commit is contained in:
terrafrost 2021-10-26 20:04:53 -05:00
parent 30a9a1541c
commit da6c1b06bf
1 changed files with 151 additions and 21 deletions
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172
phpseclib/Net/SSH2.php
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@ -150,6 +150,23 @@ define('NET_SSH2_READ_REGEX', 2);
define('NET_SSH2_READ_NEXT', 3);
/**#@-*/
/**#@+
* @access private
*/
/**
* No compression
*/
define('NET_SSH2_COMPRESSION_NONE', 1);
/**
* zlib compression
*/
define('NET_SSH2_COMPRESSION_ZLIB', 2);
/**
* zlib@openssh.com
*/
define('NET_SSH2_COMPRESSION_ZLIB_AT_OPENSSH', 3);
/**#@-*/
/**
* Pure-PHP implementation of SSHv2.
*
@ -980,8 +997,57 @@ class Net_SSH2
*
* @see https://tools.ietf.org/html/rfc4252#section-5.1
* @var array|null
* @access private
*/
private $auth_methods_to_continue = null;
var $auth_methods_to_continue = null;
/**
* Compression method
*
* @var int
* @access private
*/
var $compress = NET_SSH2_COMPRESSION_NONE;
/**
* Decompression method
*
* @var resource|object
* @access private
*/
var $decompress = NET_SSH2_COMPRESSION_NONE;
/**
* Compression context
*
* @var int
* @access private
*/
var $compress_context;
/**
* Decompression context
*
* @var resource|object
* @access private
*/
var $decompress_context;
/**
* Regenerate Compression Context
*
* @var bool
* @access private
*/
var $regenerate_compression_context = false;
/**
* Regenerate Decompression Context
*
* @var bool
* @access private
*/
var $regenerate_decompression_context = false;
/**
* Default Constructor.
@ -1590,19 +1656,25 @@ class Net_SSH2
return $this->_disconnect(NET_SSH2_DISCONNECT_KEY_EXCHANGE_FAILED);
}
$compression_map = array(
'none' => NET_SSH2_COMPRESSION_NONE,
'zlib' => NET_SSH2_COMPRESSION_ZLIB,
'zlib@openssh.com' => NET_SSH2_COMPRESSION_ZLIB_AT_OPENSSH
);
$compression_algorithm_out = $this->_array_intersect_first($c2s_compression_algorithms, $this->compression_algorithms_client_to_server);
if ($compression_algorithm_out === false) {
user_error('No compatible client to server compression algorithms found');
return $this->_disconnect(NET_SSH2_DISCONNECT_KEY_EXCHANGE_FAILED);
}
//$this->decompress = $compression_algorithm_out == 'zlib';
$this->compress = $compression_map[$compression_algorithm_out];
$compression_algorithm_in = $this->_array_intersect_first($s2c_compression_algorithms, $this->compression_algorithms_client_to_server);
$compression_algorithm_in = $this->_array_intersect_first($s2c_compression_algorithms, $this->compression_algorithms_server_to_client);
if ($compression_algorithm_in === false) {
user_error('No compatible server to client compression algorithms found');
return $this->_disconnect(NET_SSH2_DISCONNECT_KEY_EXCHANGE_FAILED);
}
//$this->compress = $compression_algorithm_in == 'zlib';
$this->decompress = $compression_map[$compression_algorithm_in];
if (strpos($kex_algorithm, 'diffie-hellman-group-exchange') === 0) {
$dh_group_sizes_packed = pack(
@ -1996,6 +2068,8 @@ class Net_SSH2
}
$this->hmac_check->setKey(substr($key, 0, $checkKeyLength));
$this->regenerate_compression_context = $this->regenerate_decompression_context = true;
return true;
}
@ -3399,7 +3473,7 @@ class Net_SSH2
if (!is_resource($this->fsock) || feof($this->fsock)) {
$this->bitmap = 0;
user_error('Connection closed (by server) prematurely');
user_error('Connection closed (by server) prematurely ' . $elapsed . 's');
return false;
}
@ -3470,9 +3544,41 @@ class Net_SSH2
}
}
//if ($this->decompress) {
// $payload = gzinflate(substr($payload, 2));
//}
switch ($this->decompress) {
case NET_SSH2_COMPRESSION_ZLIB_AT_OPENSSH:
if (!$this->isAuthenticated()) {
break;
}
case NET_SSH2_COMPRESSION_ZLIB:
if ($this->regenerate_decompression_context) {
$this->regenerate_decompression_context = false;
$cmf = ord($payload[0]);
$cm = $cmf & 0x0F;
if ($cm != 8) { // deflate
user_error("Only CM = 8 ('deflate') is supported ($cm)");
}
$cinfo = ($cmf & 0xF0) >> 4;
if ($cinfo > 7) {
user_error("CINFO above 7 is not allowed ($cinfo)");
}
$windowSize = 1 << ($cinfo + 8);
$flg = ord($payload[1]);
//$fcheck = $flg && 0x0F;
if ((($cmf << 8) | $flg) % 31) {
user_error('fcheck failed');
}
$fdict = boolval($flg & 0x20);
$flevel = ($flg & 0xC0) >> 6;
$this->decompress_context = inflate_init(ZLIB_ENCODING_RAW, ['window' => $cinfo + 8]);
$payload = substr($payload, 2);
}
if ($this->decompress_context) {
$payload = inflate_add($this->decompress_context, $payload, ZLIB_PARTIAL_FLUSH);
}
}
$this->get_seq_no++;
@ -4028,11 +4134,27 @@ class Net_SSH2
return false;
}
//if ($this->compress) {
// // the -4 removes the checksum:
// // http://php.net/function.gzcompress#57710
// $data = substr(gzcompress($data), 0, -4);
//}
if (!isset($logged)) {
$logged = $data;
}
switch ($this->compress) {
case NET_SSH2_COMPRESSION_ZLIB_AT_OPENSSH:
if (!$this->isAuthenticated()) {
break;
}
case NET_SSH2_COMPRESSION_ZLIB:
if (!$this->regenerate_compression_context) {
$header = '';
} else {
$this->regenerate_compression_context = false;
$this->compress_context = deflate_init(ZLIB_ENCODING_RAW, ['window' => 15]);
$header = "\x78\x9C";
}
if ($this->compress_context) {
$data = $header . deflate_add($this->compress_context, $data, ZLIB_PARTIAL_FLUSH);
}
}
// 4 (packet length) + 1 (padding length) + 4 (minimal padding amount) == 9
$packet_length = strlen($data) + 9;
@ -4060,10 +4182,10 @@ class Net_SSH2
if (defined('NET_SSH2_LOGGING')) {
$current = strtok(microtime(), ' ') + strtok('');
$message_number = isset($this->message_numbers[ord($data[0])]) ? $this->message_numbers[ord($data[0])] : 'UNKNOWN (' . ord($data[0]) . ')';
$message_number = isset($this->message_numbers[ord($logged[0])]) ? $this->message_numbers[ord($logged[0])] : 'UNKNOWN (' . ord($logged[0]) . ')';
$message_number = '-> ' . $message_number .
' (since last: ' . round($current - $this->last_packet, 4) . ', network: ' . round($stop - $start, 4) . 's)';
$this->_append_log($message_number, isset($logged) ? $logged : $data);
$this->_append_log($message_number, $logged);
$this->last_packet = $current;
}
@ -4746,10 +4868,12 @@ class Net_SSH2
*/
function getSupportedCompressionAlgorithms()
{
return array(
'none' // REQUIRED no compression
//'zlib' // OPTIONAL ZLIB (LZ77) compression
);
$algos = array('none'); // REQUIRED no compression
if (function_exists('deflate_init')) {
$algos[] = 'zlib@openssh.com'; // https://datatracker.ietf.org/doc/html/draft-miller-secsh-compression-delayed
$algos[] = 'zlib';
}
return $algos;
}
/**
@ -4764,18 +4888,24 @@ class Net_SSH2
{
$this->_connect();
$compression_map = array(
NET_SSH2_COMPRESSION_NONE => 'none',
NET_SSH2_COMPRESSION_ZLIB => 'zlib',
NET_SSH2_COMPRESSION_ZLIB_AT_OPENSSH => 'zlib@openssh.com'
);
return array(
'kex' => $this->kex_algorithm,
'hostkey' => $this->signature_format,
'client_to_server' => array(
'crypt' => $this->encrypt->name,
'mac' => $this->hmac_create->name,
'comp' => 'none',
'comp' => $compression_map[$this->compress],
),
'server_to_client' => array(
'crypt' => $this->decrypt->name,
'mac' => $this->hmac_check->name,
'comp' => 'none',
'comp' => $compression_map[$this->decompress],
)
);
}