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SSH2: send KEXINIT packet and identification string first or last

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This commit is contained in:
terrafrost 2017-08-07 00:15:50 -05:00
parent acebfe28d6
commit 7ccb0d0b02
1 changed files with 142 additions and 43 deletions
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185
phpseclib/Net/SSH2.php
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@ -875,6 +875,22 @@ class Net_SSH2
*/
var $agent;
/**
* Send the identification string first?
*
* @var bool
* @access private
*/
var $send_id_string_first = true;
/**
* Send the key exchange initiation packet first?
*
* @var bool
* @access private
*/
var $send_kex_first = true;
/**
* Default Constructor.
*
@ -1017,13 +1033,69 @@ class Net_SSH2
* CRYPT_MODE_INTERNAL, CRYPT_MODE_MCRYPT
*
* @param int $engine
* @access private
* @access public
*/
function setCryptoEngine($engine)
{
$this->crypto_engine = $engine;
}
/**
* Send Identification String First
*
* https://tools.ietf.org/html/rfc4253#section-4.2 says "when the connection has been established,
* both sides MUST send an identification string". It does not say which side sends it first. In
* theory it shouldn't matter but it is a fact of life that some SSH servers are simply buggy
*
* @access public
*/
function sendIdentificationStringFirst()
{
$this->send_id_string_first = true;
}
/**
* Send Identification String Last
*
* https://tools.ietf.org/html/rfc4253#section-4.2 says "when the connection has been established,
* both sides MUST send an identification string". It does not say which side sends it first. In
* theory it shouldn't matter but it is a fact of life that some SSH servers are simply buggy
*
* @access public
*/
function sendIdentificationStringLast()
{
$this->send_id_string_first = false;
}
/**
* Send SSH_MSG_KEXINIT First
*
* https://tools.ietf.org/html/rfc4253#section-7.1 says "key exchange begins by each sending
* sending the [SSH_MSG_KEXINIT] packet". It does not say which side sends it first. In theory
* it shouldn't matter but it is a fact of life that some SSH servers are simply buggy
*
* @access public
*/
function sendKEXINITFirst()
{
$this->send_kex_first = true;
}
/**
* Send SSH_MSG_KEXINIT Last
*
* https://tools.ietf.org/html/rfc4253#section-7.1 says "key exchange begins by each sending
* sending the [SSH_MSG_KEXINIT] packet". It does not say which side sends it first. In theory
* it shouldn't matter but it is a fact of life that some SSH servers are simply buggy
*
* @access public
*/
function sendKEXINITLast()
{
$this->send_kex_first = false;
}
/**
* Connect to an SSHv2 server
*
@ -1065,7 +1137,9 @@ class Net_SSH2
$this->identifier = $this->_generate_identifier();
fputs($this->fsock, $this->identifier . "\r\n");
if ($this->send_id_string_first) {
fputs($this->fsock, $this->identifier . "\r\n");
}
/* According to the SSH2 specs,
@ -1125,18 +1199,28 @@ class Net_SSH2
return false;
}
$response = $this->_get_binary_packet();
if ($response === false) {
user_error('Connection closed by server');
return false;
if (!$this->send_id_string_first) {
fputs($this->fsock, $this->identifier . "\r\n");
}
if (!strlen($response) || ord($response[0]) != NET_SSH2_MSG_KEXINIT) {
user_error('Expected SSH_MSG_KEXINIT');
return false;
if (!$this->send_kex_first) {
$response = $this->_get_binary_packet();
if ($response === false) {
user_error('Connection closed by server');
return false;
}
if (!strlen($response) || ord($response[0]) != NET_SSH2_MSG_KEXINIT) {
user_error('Expected SSH_MSG_KEXINIT');
return false;
}
if (!$this->_key_exchange($response)) {
return false;
}
}
if (!$this->_key_exchange($response)) {
if ($this->send_kex_first && !$this->_key_exchange()) {
return false;
}
@ -1180,10 +1264,10 @@ class Net_SSH2
/**
* Key Exchange
*
* @param string $kexinit_payload_server
* @param string $kexinit_payload_server optional
* @access private
*/
function _key_exchange($kexinit_payload_server)
function _key_exchange($kexinit_payload_server = false)
{
static $kex_algorithms = array(
'diffie-hellman-group1-sha1', // REQUIRED
@ -1317,6 +1401,51 @@ class Net_SSH2
$client_cookie = crypt_random_string(16);
$kexinit_payload_client = pack(
'Ca*Na*Na*Na*Na*Na*Na*Na*Na*Na*Na*CN',
NET_SSH2_MSG_KEXINIT,
$client_cookie,
strlen($str_kex_algorithms),
$str_kex_algorithms,
strlen($str_server_host_key_algorithms),
$str_server_host_key_algorithms,
strlen($encryption_algorithms_client_to_server),
$encryption_algorithms_client_to_server,
strlen($encryption_algorithms_server_to_client),
$encryption_algorithms_server_to_client,
strlen($mac_algorithms_client_to_server),
$mac_algorithms_client_to_server,
strlen($mac_algorithms_server_to_client),
$mac_algorithms_server_to_client,
strlen($compression_algorithms_client_to_server),
$compression_algorithms_client_to_server,
strlen($compression_algorithms_server_to_client),
$compression_algorithms_server_to_client,
0,
'',
0,
'',
0,
0
);
if ($this->send_kex_first) {
if (!$this->_send_binary_packet($kexinit_payload_client)) {
return false;
}
$kexinit_payload_server = $this->_get_binary_packet();
if ($kexinit_payload_server === false) {
user_error('Connection closed by server');
return false;
}
if (!strlen($kexinit_payload_server) || ord($kexinit_payload_server[0]) != NET_SSH2_MSG_KEXINIT) {
user_error('Expected SSH_MSG_KEXINIT');
return false;
}
}
$response = $kexinit_payload_server;
$this->_string_shift($response, 1); // skip past the message number (it should be SSH_MSG_KEXINIT)
$server_cookie = $this->_string_shift($response, 16);
@ -1387,39 +1516,9 @@ class Net_SSH2
extract(unpack('Cfirst_kex_packet_follows', $this->_string_shift($response, 1)));
$first_kex_packet_follows = $first_kex_packet_follows != 0;
// the sending of SSH2_MSG_KEXINIT could go in one of two places. this is the second place.
$kexinit_payload_client = pack(
'Ca*Na*Na*Na*Na*Na*Na*Na*Na*Na*Na*CN',
NET_SSH2_MSG_KEXINIT,
$client_cookie,
strlen($str_kex_algorithms),
$str_kex_algorithms,
strlen($str_server_host_key_algorithms),
$str_server_host_key_algorithms,
strlen($encryption_algorithms_client_to_server),
$encryption_algorithms_client_to_server,
strlen($encryption_algorithms_server_to_client),
$encryption_algorithms_server_to_client,
strlen($mac_algorithms_client_to_server),
$mac_algorithms_client_to_server,
strlen($mac_algorithms_server_to_client),
$mac_algorithms_server_to_client,
strlen($compression_algorithms_client_to_server),
$compression_algorithms_client_to_server,
strlen($compression_algorithms_server_to_client),
$compression_algorithms_server_to_client,
0,
'',
0,
'',
0,
0
);
if (!$this->_send_binary_packet($kexinit_payload_client)) {
if (!$this->send_kex_first && !$this->_send_binary_packet($kexinit_payload_client)) {
return false;
}
// here ends the second place.
// we need to decide upon the symmetric encryption algorithms before we do the diffie-hellman key exchange
// we don't initialize any crypto-objects, yet - we do that, later. for now, we need the lengths to make the