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1	<?php
2
3	/**
4	* Pure-PHP ssh-agent client.
5	*
6	* PHP versions 4 and 5
7	*
8	* Here are some examples of how to use this library:
9	* <code>
10	* <?php
11	* include 'System/SSH/Agent.php';
12	* include 'Net/SSH2.php';
13	*
14	* $agent = new System_SSH_Agent();
15	*
16	* $ssh = new Net_SSH2('www.domain.tld');
17	* if (!$ssh->login('username', $agent)) {
18	* exit('Login Failed');
19	* }
20	*
21	* echo $ssh->exec('pwd');
22	* echo $ssh->exec('ls -la');
23	* ?>
24	* </code>
25	*
26	* LICENSE: Permission is hereby granted, free of charge, to any person obtaining a copy
27	* of this software and associated documentation files (the "Software"), to deal
28	* in the Software without restriction, including without limitation the rights
29	* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
30	* copies of the Software, and to permit persons to whom the Software is
31	* furnished to do so, subject to the following conditions:
32	*
33	* The above copyright notice and this permission notice shall be included in
34	* all copies or substantial portions of the Software.
35	*
36	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
37	* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
38	* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
39	* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
40	* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
41	* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
42	* THE SOFTWARE.
43	*
44	* @category System
45	* @package System_SSH_Agent
46	* @author Jim Wigginton <[email protected]>
47	* @copyright 2014 Jim Wigginton
48	* @license http://www.opensource.org/licenses/mit-license.html MIT License
49	* @link http://phpseclib.sourceforge.net
50	* @internal See http://api.libssh.org/rfc/PROTOCOL.agent
51	*/
52
53	/**#@+
54	* Message numbers
55	*
56	* @access private
57	*/
58	// to request SSH1 keys you have to use SSH_AGENTC_REQUEST_RSA_IDENTITIES (1)
59	define('SYSTEM_SSH_AGENTC_REQUEST_IDENTITIES', 11);
60	// this is the SSH2 response; the SSH1 response is SSH_AGENT_RSA_IDENTITIES_ANSWER (2).
61	define('SYSTEM_SSH_AGENT_IDENTITIES_ANSWER', 12);
62	define('SYSTEM_SSH_AGENT_FAILURE', 5);
63	// the SSH1 request is SSH_AGENTC_RSA_CHALLENGE (3)
64	define('SYSTEM_SSH_AGENTC_SIGN_REQUEST', 13);
65	// the SSH1 response is SSH_AGENT_RSA_RESPONSE (4)
66	define('SYSTEM_SSH_AGENT_SIGN_RESPONSE', 14);
67	/*#@-/
68
69	/**@+
70	* Agent forwarding status
71	*
72	* @access private
73	*/
74	// no forwarding requested and not active
75	define('SYSTEM_SSH_AGENT_FORWARD_NONE', 0);
76	// request agent forwarding when opportune
77	define('SYSTEM_SSH_AGENT_FORWARD_REQUEST', 1);
78	// forwarding has been request and is active
79	define('SYSTEM_SSH_AGENT_FORWARD_ACTIVE', 2);
80	/*#@-/
81
82	/**@+
83	* Signature Flags
84	*
85	* See https://tools.ietf.org/html/draft-miller-ssh-agent-00#section-5.3
86	*
87	* @access private
88	*/
89	define('SYSTEM_SSH_AGENT_RSA2_256', 2);
90	define('SYSTEM_SSH_AGENT_RSA2_512', 4);
91	/*#@-/
92
93	/**
94	* Pure-PHP ssh-agent client identity object
95	*
96	* Instantiation should only be performed by System_SSH_Agent class.
97	* This could be thought of as implementing an interface that Crypt_RSA
98	* implements. ie. maybe a Net_SSH_Auth_PublicKey interface or something.
99	* The methods in this interface would be getPublicKey, setSignatureMode
100	* and sign since those are the methods phpseclib looks for to perform
101	* public key authentication.
102	*
103	* @package System_SSH_Agent
104	* @author Jim Wigginton <[email protected]>
105	* @access internal
106	*/
107	class System_SSH_Agent_Identity
108	{
109	/**
110	* Key Object
111	*
112	* @var Crypt_RSA
113	* @access private
114	* @see self::getPublicKey()
115	*/
116	var $key;
117
118	/**
119	* Key Blob
120	*
121	* @var string
122	* @access private
123	* @see self::sign()
124	*/
125	var $key_blob;
126
127	/**
128	* Socket Resource
129	*
130	* @var resource
131	* @access private
132	* @see self::sign()
133	*/
134	var $fsock;
135
136	/**
137	* Signature flags
138	*
139	* @var int
140	* @access private
141	* @see self::sign()
142	* @see self::setHash()
143	*/
144	var $flags = 0;
145
146	/**
147	* Default Constructor.
148	*
149	* @param resource $fsock
150	* @return System_SSH_Agent_Identity
151	* @access private
152	*/
153	function __construct($fsock)
154	{
155	$this->fsock = $fsock;
156	}
157
158	/**
159	* PHP4 compatible Default Constructor.
160	*
161	* @see self::__construct()
162	* @param resource $fsock
163	* @access public
164	*/
165	function System_SSH_Agent_Identity($fsock)
166	{
167	$this->__construct($fsock);
168	}
169
170	/**
171	* Set Public Key
172	*
173	* Called by System_SSH_Agent::requestIdentities()
174	*
175	* @param Crypt_RSA $key
176	* @access private
177	*/
178	function setPublicKey($key)
179	{
180	$this->key = $key;
181	$this->key->setPublicKey();
182	}
183
184	/**
185	* Set Public Key
186	*
187	* Called by System_SSH_Agent::requestIdentities(). The key blob could be extracted from $this->key
188	* but this saves a small amount of computation.
189	*
190	* @param string $key_blob
191	* @access private
192	*/
193	function setPublicKeyBlob($key_blob)
194	{
195	$this->key_blob = $key_blob;
196	}
197
198	/**
199	* Get Public Key
200	*
201	* Wrapper for $this->key->getPublicKey()
202	*
203	* @param int $format optional
204	* @return mixed
205	* @access public
206	*/
207	function getPublicKey($format = null)
208	{
209	return !isset($format) ? $this->key->getPublicKey() : $this->key->getPublicKey($format);
210	}
211
212	/**
213	* Set Signature Mode
214	*
215	* Doesn't do anything as ssh-agent doesn't let you pick and choose the signature mode. ie.
216	* ssh-agent's only supported mode is CRYPT_RSA_SIGNATURE_PKCS1
217	*
218	* @param int $mode
219	* @access public
220	*/
221	function setSignatureMode($mode)
222	{
223	}
224
225	/**
226	* Set Hash
227	*
228	* ssh-agent doesn't support using hashes for RSA other than SHA1
229	*
230	* @param string $hash
231	* @access public
232	*/
233	function setHash($hash)
234	{
235	$this->flags = 0;
236	switch ($hash) {
237	case 'sha1':
238	break;
239	case 'sha256':
240	$this->flags = SYSTEM_SSH_AGENT_RSA2_256;
241	break;
242	case 'sha512':
243	$this->flags = SYSTEM_SSH_AGENT_RSA2_512;
244	break;
245	default:
246	user_error('The only supported hashes for RSA are sha1, sha256 and sha512');
247	}
248	}
249
250	/**
251	* Create a signature
252	*
253	* See "2.6.2 Protocol 2 private key signature request"
254	*
255	* @param string $message
256	* @return string
257	* @access public
258	*/
259	function sign($message)
260	{
261	// the last parameter (currently 0) is for flags and ssh-agent only defines one flag (for ssh-dss): SSH_AGENT_OLD_SIGNATURE
262	$packet = pack('CNaNaN', SYSTEM_SSH_AGENTC_SIGN_REQUEST, strlen($this->key_blob), $this->key_blob, strlen($message), $message, $this->flags);
263	$packet = pack('Na*', strlen($packet), $packet);
264	if (strlen($packet) != fputs($this->fsock, $packet)) {
265	user_error('Connection closed during signing');
266	return false;
267	}
268
269	$temp = fread($this->fsock, 4);
270	if (strlen($temp) != 4) {
271	user_error('Connection closed during signing');
272	return false;
273	}
274	$length = current(unpack('N', $temp));
275	$type = ord(fread($this->fsock, 1));
276	if ($type != SYSTEM_SSH_AGENT_SIGN_RESPONSE) {
277	user_error('Unable to retreive signature');
278	return false;
279	}
280
281	$signature_blob = fread($this->fsock, $length - 1);
282	if (strlen($signature_blob) != $length - 1) {
283	user_error('Connection closed during signing');
284	return false;
285	}
286	$length = current(unpack('N', $this->_string_shift($signature_blob, 4)));
287	if ($length != strlen($signature_blob)) {
288	user_error('Malformed signature blob');
289	return false;
290	}
291	$length = current(unpack('N', $this->_string_shift($signature_blob, 4)));
292	if ($length > strlen($signature_blob) + 4) {
293	user_error('Malformed signature blob');
294	return false;
295	}
296	$type = $this->_string_shift($signature_blob, $length);
297	$this->_string_shift($signature_blob, 4);
298
299	return $signature_blob;
300	}
301
302	/**
303	* String Shift
304	*
305	* Inspired by array_shift
306	*
307	* @param string $string
308	* @param int $index
309	* @return string
310	* @access private
311	*/
312	function _string_shift(&$string, $index = 1)
313	{
314	$substr = substr($string, 0, $index);
315	$string = substr($string, $index);
316	return $substr;
317	}
318	}
319
320	/**
321	* Pure-PHP ssh-agent client identity factory
322	*
323	* requestIdentities() method pumps out System_SSH_Agent_Identity objects
324	*
325	* @package System_SSH_Agent
326	* @author Jim Wigginton <[email protected]>
327	* @access public
328	*/
329	class System_SSH_Agent
330	{
331	/**
332	* Socket Resource
333	*
334	* @var resource
335	* @access private
336	*/
337	var $fsock;
338
339	/**
340	* Agent forwarding status
341	*
342	* @access private
343	*/
344	var $forward_status = SYSTEM_SSH_AGENT_FORWARD_NONE;
345
346	/**
347	* Buffer for accumulating forwarded authentication
348	* agent data arriving on SSH data channel destined
349	* for agent unix socket
350	*
351	* @access private
352	*/
353	var $socket_buffer = '';
354
355	/**
356	* Tracking the number of bytes we are expecting
357	* to arrive for the agent socket on the SSH data
358	* channel
359	*/
360	var $expected_bytes = 0;
361
362	/**
363	* Default Constructor
364	*
365	* @return System_SSH_Agent
366	* @access public
367	*/
368	function __construct($address = null)
369	{
370	if (!$address) {
371	switch (true) {
372	case isset($_SERVER['SSH_AUTH_SOCK']):
373	$address = $_SERVER['SSH_AUTH_SOCK'];
374	break;
375	case isset($_ENV['SSH_AUTH_SOCK']):
376	$address = $_ENV['SSH_AUTH_SOCK'];
377	break;
378	default:
379	user_error('SSH_AUTH_SOCK not found');
380	return false;
381	}
382	}
383
384	$this->fsock = fsockopen('unix://' . $address, 0, $errno, $errstr);
385	if (!$this->fsock) {
386	user_error("Unable to connect to ssh-agent (Error $errno: $errstr)");
387	}
388	}
389
390	/**
391	* PHP4 compatible Default Constructor.
392	*
393	* @see self::__construct()
394	* @access public
395	*/
396	function System_SSH_Agent($address = null)
397	{
398	$this->__construct($address);
399	}
400
401	/**
402	* Request Identities
403	*
404	* See "2.5.2 Requesting a list of protocol 2 keys"
405	* Returns an array containing zero or more System_SSH_Agent_Identity objects
406	*
407	* @return array
408	* @access public
409	*/
410	function requestIdentities()
411	{
412	if (!$this->fsock) {
413	return array();
414	}
415
416	$packet = pack('NC', 1, SYSTEM_SSH_AGENTC_REQUEST_IDENTITIES);
417	if (strlen($packet) != fputs($this->fsock, $packet)) {
418	user_error('Connection closed while requesting identities');
419	return array();
420	}
421
422	$temp = fread($this->fsock, 4);
423	if (strlen($temp) != 4) {
424	user_error('Connection closed while requesting identities');
425	return array();
426	}
427	$length = current(unpack('N', $temp));
428	$type = ord(fread($this->fsock, 1));
429	if ($type != SYSTEM_SSH_AGENT_IDENTITIES_ANSWER) {
430	user_error('Unable to request identities');
431	return array();
432	}
433
434	$identities = array();
435	$temp = fread($this->fsock, 4);
436	if (strlen($temp) != 4) {
437	user_error('Connection closed while requesting identities');
438	return array();
439	}
440	$keyCount = current(unpack('N', $temp));
441	for ($i = 0; $i < $keyCount; $i++) {
442	$temp = fread($this->fsock, 4);
443	if (strlen($temp) != 4) {
444	user_error('Connection closed while requesting identities');
445	return array();
446	}
447	$length = current(unpack('N', $temp));
448	$key_blob = fread($this->fsock, $length);
449	if (strlen($key_blob) != $length) {
450	user_error('Connection closed while requesting identities');
451	return array();
452	}
453	$key_str = 'ssh-rsa ' . base64_encode($key_blob);
454	$temp = fread($this->fsock, 4);
455	if (strlen($temp) != 4) {
456	user_error('Connection closed while requesting identities');
457	return array();
458	}
459	$length = current(unpack('N', $temp));
460	if ($length) {
461	$temp = fread($this->fsock, $length);
462	if (strlen($temp) != $length) {
463	user_error('Connection closed while requesting identities');
464	return array();
465	}
466	$key_str.= ' ' . $temp;
467	}
468	$length = current(unpack('N', substr($key_blob, 0, 4)));
469	$key_type = substr($key_blob, 4, $length);
470	switch ($key_type) {
471	case 'ssh-rsa':
472	if (!class_exists('Crypt_RSA')) {
473	include_once 'Crypt/RSA.php';
474	}
475	$key = new Crypt_RSA();
476	$key->loadKey($key_str);
477	break;
478	case 'ssh-dss':
479	// not currently supported
480	break;
481	}
482	// resources are passed by reference by default
483	if (isset($key)) {
484	$identity = new System_SSH_Agent_Identity($this->fsock);
485	$identity->setPublicKey($key);
486	$identity->setPublicKeyBlob($key_blob);
487	$identities[] = $identity;
488	unset($key);
489	}
490	}
491
492	return $identities;
493	}
494
495	/**
496	* Signal that agent forwarding should
497	* be requested when a channel is opened
498	*
499	* @return bool
500	* @access public
501	*/
502	function startSSHForwarding()
503	{
504	if ($this->forward_status == SYSTEM_SSH_AGENT_FORWARD_NONE) {
505	$this->forward_status = SYSTEM_SSH_AGENT_FORWARD_REQUEST;
506	}
507	}
508
509	/**
510	* Request agent forwarding of remote server
511	*
512	* @param Net_SSH2 $ssh
513	* @return bool
514	* @access private
515	*/
516	function _request_forwarding($ssh)
517	{
518	$request_channel = $ssh->_get_open_channel();
519	if ($request_channel === false) {
520	return false;
521	}
522
523	$packet = pack(
524	'CNNa*C',
525	NET_SSH2_MSG_CHANNEL_REQUEST,
526	$ssh->server_channels[$request_channel],
527	strlen('[email protected]'),
528	'[email protected]',
529	1
530	);
531
532	$ssh->channel_status[$request_channel] = NET_SSH2_MSG_CHANNEL_REQUEST;
533
534	if (!$ssh->_send_binary_packet($packet)) {
535	return false;
536	}
537
538	$response = $ssh->_get_channel_packet($request_channel);
539	if ($response === false) {
540	return false;
541	}
542
543	$ssh->channel_status[$request_channel] = NET_SSH2_MSG_CHANNEL_OPEN;
544	$this->forward_status = SYSTEM_SSH_AGENT_FORWARD_ACTIVE;
545
546	return true;
547	}
548
549	/**
550	* On successful channel open
551	*
552	* This method is called upon successful channel
553	* open to give the SSH Agent an opportunity
554	* to take further action. i.e. request agent forwarding
555	*
556	* @param Net_SSH2 $ssh
557	* @access private
558	*/
559	function _on_channel_open($ssh)
560	{
561	if ($this->forward_status == SYSTEM_SSH_AGENT_FORWARD_REQUEST) {
562	$this->_request_forwarding($ssh);
563	}
564	}
565
566	/**
567	* Forward data to SSH Agent and return data reply
568	*
569	* @param string $data
570	* @return data from SSH Agent
571	* @access private
572	*/
573	function _forward_data($data)
574	{
575	if ($this->expected_bytes > 0) {
576	$this->socket_buffer.= $data;
577	$this->expected_bytes -= strlen($data);
578	} else {
579	$agent_data_bytes = current(unpack('N', $data));
580	$current_data_bytes = strlen($data);
581	$this->socket_buffer = $data;
582	if ($current_data_bytes != $agent_data_bytes + 4) {
583	$this->expected_bytes = ($agent_data_bytes + 4) - $current_data_bytes;
584	return false;
585	}
586	}
587
588	if (strlen($this->socket_buffer) != fwrite($this->fsock, $this->socket_buffer)) {
589	user_error('Connection closed attempting to forward data to SSH agent');
590	return false;
591	}
592
593	$this->socket_buffer = '';
594	$this->expected_bytes = 0;
595
596	$temp = fread($this->fsock, 4);
597	if (strlen($temp) != 4) {
598	user_error('Connection closed while reading data response');
599	return false;
600	}
601	$agent_reply_bytes = current(unpack('N', $temp));
602
603	$agent_reply_data = fread($this->fsock, $agent_reply_bytes);
604	if (strlen($agent_reply_data) != $agent_reply_bytes) {
605	user_error('Connection closed while reading data response');
606	return false;
607	}
608	$agent_reply_data = current(unpack('a*', $agent_reply_data));
609
610	return pack('Na*', $agent_reply_bytes, $agent_reply_data);
611	}
612	}
613