Merge pull request #1697 from terrafrost/sftpv456-3.0

add SFTP v4/5/6 support to phpseclib v3

phpseclib/Common/Functions/Strings.php

@@ -70,6 +70,7 @@ abstract class Strings
      * C = byte
      * b = boolean (true/false)
      * N = uint32
+     * Q = uint64
      * s = string
      * i = mpint
      * L = name-list
@@ -100,6 +101,12 @@ abstract class Strings
                         throw new \LengthException('At least four byte needs to be present for successful N / i / s / L decodes');
                     }
                     break;
+                case 'Q':
+                    if (strlen($data) < 8) {
+                        throw new \LengthException('At least eight byte needs to be present for successful N / i / s / L decodes');
+                    }
+                    break;
+
                 default:
                     throw new \InvalidArgumentException('$format contains an invalid character');
             }
@@ -114,6 +121,19 @@ abstract class Strings
                     list(, $temp) = unpack('N', self::shift($data, 4));
                     $result[] = $temp;
                     continue 2;
+                case 'Q':
+                    // pack() added support for Q in PHP 5.6.3 and PHP 5.6 is phpseclib 3's minimum version
+                    // so in theory we could support this BUT, "64-bit format codes are not available for
+                    // 32-bit versions" and phpseclib works on 32-bit installs. on 32-bit installs
+                    // 64-bit floats can be used to get larger numbers then 32-bit signed ints would allow
+                    // for. sure, you're not gonna get the full precision of 64-bit numbers but just because
+                    // you need > 32-bit precision doesn't mean you need the full 64-bit precision
+                    extract(unpack('Nupper/Nlower', self::shift($data, 8)));
+                    $temp = $upper ? 4294967296 * $upper : 0;
+                    $temp+= $lower < 0 ? ($lower & 0x7FFFFFFFF) + 0x80000000 : $lower;
+                    // $temp = hexdec(bin2hex(self::shift($data, 8)));
+                    $result[] = $temp;
+                    continue 2;
             }
             list(, $length) = unpack('N', self::shift($data, 4));
             if (strlen($data) < $length) {
@@ -165,6 +185,13 @@ abstract class Strings
                     }
                     $result.= $element ? "\1" : "\0";
                     break;
+                case 'Q':
+                    if (!is_int($element) && !is_float($element)) {
+                        throw new \InvalidArgumentException('An integer was expected.');
+                    }
+                    // 4294967296 == 1 << 32
+                    $result.= pack('NN', $element / 4294967296, $element);
+                    break;
                 case 'N':
                     if (is_float($element)) {
                         $element = (int) $element;

phpseclib/Net/SFTP.php

@@ -5,9 +5,7 @@
  *
  * PHP version 5
  *
- * Currently only supports SFTPv2 and v3, which, according to wikipedia.org, "is the most widely used version,
+ * Supports SFTPv2/3/4/5/6. Defaults to v3.
- * implemented by the popular OpenSSH SFTP server".  If you want SFTPv4/5/6 support, provide me with access
- * to an SFTPv4/5/6 server.
  *
  * The API for this library is modeled after the API from PHP's {@link http://php.net/book.ftp FTP extension}.
  *
@@ -169,6 +167,24 @@ class SFTP extends SSH2
      */
     private $version;
 
+    /**
+     * Default Server SFTP version
+     *
+     * @var int
+     * @see self::_initChannel()
+     * @access private
+     */
+    private $defaultVersion;
+
+    /**
+     * Preferred SFTP version
+     *
+     * @var int
+     * @see self::_initChannel()
+     * @access private
+     */
+    private $preferredVersion = 3;
+
     /**
      * Current working directory
      *
@@ -297,7 +313,7 @@ class SFTP extends SSH2
      * @var bool
      * @access private
      */
-    var $allow_arbitrary_length_packets = false;
+    private $allow_arbitrary_length_packets = false;
 
     /**
      * Was the last packet due to the channels being closed or not?
@@ -309,6 +325,14 @@ class SFTP extends SSH2
      */
     private $channel_close = false;
 
+    /**
+     * Has the SFTP channel been partially negotiated?
+     *
+     * @var bool
+     * @access private
+     */
+    private $partial_init = false;
+
     /**
      * Default Constructor.
      *
@@ -329,15 +353,13 @@ class SFTP extends SSH2
         $this->packet_types = [
             1  => 'NET_SFTP_INIT',
             2  => 'NET_SFTP_VERSION',
-            /* the format of SSH_FXP_OPEN changed between SFTPv4 and SFTPv5+:
-                   SFTPv5+: http://tools.ietf.org/html/draft-ietf-secsh-filexfer-13#section-8.1.1
-               pre-SFTPv5 : http://tools.ietf.org/html/draft-ietf-secsh-filexfer-04#section-6.3 */
             3  => 'NET_SFTP_OPEN',
             4  => 'NET_SFTP_CLOSE',
             5  => 'NET_SFTP_READ',
             6  => 'NET_SFTP_WRITE',
             7  => 'NET_SFTP_LSTAT',
             9  => 'NET_SFTP_SETSTAT',
+            10 => 'NET_SFTP_FSETSTAT',
             11 => 'NET_SFTP_OPENDIR',
             12 => 'NET_SFTP_READDIR',
             13 => 'NET_SFTP_REMOVE',
@@ -345,18 +367,13 @@ class SFTP extends SSH2
             15 => 'NET_SFTP_RMDIR',
             16 => 'NET_SFTP_REALPATH',
             17 => 'NET_SFTP_STAT',
-            /* the format of SSH_FXP_RENAME changed between SFTPv4 and SFTPv5+:
-                   SFTPv5+: http://tools.ietf.org/html/draft-ietf-secsh-filexfer-13#section-8.3
-               pre-SFTPv5 : http://tools.ietf.org/html/draft-ietf-secsh-filexfer-04#section-6.5 */
             18 => 'NET_SFTP_RENAME',
             19 => 'NET_SFTP_READLINK',
             20 => 'NET_SFTP_SYMLINK',
+            21 => 'NET_SFTP_LINK',
 
             101=> 'NET_SFTP_STATUS',
             102=> 'NET_SFTP_HANDLE',
-            /* the format of SSH_FXP_NAME changed between SFTPv3 and SFTPv4+:
-                   SFTPv4+: http://tools.ietf.org/html/draft-ietf-secsh-filexfer-13#section-9.4
-               pre-SFTPv4 : http://tools.ietf.org/html/draft-ietf-secsh-filexfer-02#section-7 */
             103=> 'NET_SFTP_DATA',
             104=> 'NET_SFTP_NAME',
             105=> 'NET_SFTP_ATTRS',
@@ -402,8 +419,20 @@ class SFTP extends SSH2
         $this->attributes = [
             0x00000001 => 'NET_SFTP_ATTR_SIZE',
             0x00000002 => 'NET_SFTP_ATTR_UIDGID',          // defined in SFTPv3, removed in SFTPv4+
+            0x00000080 => 'NET_SFTP_ATTR_OWNERGROUP',      // defined in SFTPv4+
             0x00000004 => 'NET_SFTP_ATTR_PERMISSIONS',
             0x00000008 => 'NET_SFTP_ATTR_ACCESSTIME',
+            0x00000010 => 'NET_SFTP_ATTR_CREATETIME',      // SFTPv4+
+            0x00000020 => 'NET_SFTP_ATTR_MODIFYTIME',
+            0x00000040 => 'NET_SFTP_ATTR_ACL',
+            0x00000100 => 'NET_SFTP_ATTR_SUBSECOND_TIMES',
+            0x00000200 => 'NET_SFTP_ATTR_BITS',            // SFTPv5+
+            0x00000400 => 'NET_SFTP_ATTR_ALLOCATION_SIZE', // SFTPv6+
+            0x00000800 => 'NET_SFTP_ATTR_TEXT_HINT',
+            0x00001000 => 'NET_SFTP_ATTR_MIME_TYPE',
+            0x00002000 => 'NET_SFTP_ATTR_LINK_COUNT',
+            0x00004000 => 'NET_SFTP_ATTR_UNTRANSLATED_NAME',
+            0x00008000 => 'NET_SFTP_ATTR_CTIME',
             // 0x80000000 will yield a floating point on 32-bit systems and converting floating points to integers
             // yields inconsistent behavior depending on how php is compiled.  so we left shift -1 (which, in
             // two's compliment, consists of all 1 bits) by 31.  on 64-bit systems this'll yield 0xFFFFFFFF80000000.
@@ -419,7 +448,32 @@ class SFTP extends SSH2
             0x00000004 => 'NET_SFTP_OPEN_APPEND',
             0x00000008 => 'NET_SFTP_OPEN_CREATE',
             0x00000010 => 'NET_SFTP_OPEN_TRUNCATE',
-            0x00000020 => 'NET_SFTP_OPEN_EXCL'
+            0x00000020 => 'NET_SFTP_OPEN_EXCL',
+            0x00000040 => 'NET_SFTP_OPEN_TEXT' // defined in SFTPv4
+        ];
+        // SFTPv5+ changed the flags up:
+        // https://datatracker.ietf.org/doc/html/draft-ietf-secsh-filexfer-13#section-8.1.1.3
+        $this->open_flags5 = [
+            // when SSH_FXF_ACCESS_DISPOSITION is a 3 bit field that controls how the file is opened
+            0x00000000 => 'NET_SFTP_OPEN_CREATE_NEW',
+            0x00000001 => 'NET_SFTP_OPEN_CREATE_TRUNCATE',
+            0x00000002 => 'NET_SFTP_OPEN_OPEN_EXISTING',
+            0x00000003 => 'NET_SFTP_OPEN_OPEN_OR_CREATE',
+            0x00000004 => 'NET_SFTP_OPEN_TRUNCATE_EXISTING',
+            // the rest of the flags are not supported
+            0x00000008 => 'NET_SFTP_OPEN_APPEND_DATA', // "the offset field of SS_FXP_WRITE requests is ignored"
+            0x00000010 => 'NET_SFTP_OPEN_APPEND_DATA_ATOMIC',
+            0x00000020 => 'NET_SFTP_OPEN_TEXT_MODE',
+            0x00000040 => 'NET_SFTP_OPEN_BLOCK_READ',
+            0x00000080 => 'NET_SFTP_OPEN_BLOCK_WRITE',
+            0x00000100 => 'NET_SFTP_OPEN_BLOCK_DELETE',
+            0x00000200 => 'NET_SFTP_OPEN_BLOCK_ADVISORY',
+            0x00000400 => 'NET_SFTP_OPEN_NOFOLLOW',
+            0x00000800 => 'NET_SFTP_OPEN_DELETE_ON_CLOSE',
+            0x00001000 => 'NET_SFTP_OPEN_ACCESS_AUDIT_ALARM_INFO',
+            0x00002000 => 'NET_SFTP_OPEN_ACCESS_BACKUP',
+            0x00004000 => 'NET_SFTP_OPEN_BACKUP_STREAM',
+            0x00008000 => 'NET_SFTP_OPEN_OVERRIDE_OWNER',
         ];
         // http://tools.ietf.org/html/draft-ietf-secsh-filexfer-04#section-5.2
         // see \phpseclib3\Net\SFTP::_parseLongname() for an explanation
@@ -441,6 +495,7 @@ class SFTP extends SSH2
             $this->status_codes,
             $this->attributes,
             $this->open_flags,
+            $this->open_flags5,
             $this->file_types
         );
 
@@ -453,31 +508,32 @@ class SFTP extends SSH2
     }
 
     /**
-     * Login
+     * Check a few things before SFTP functions are called
+     *
+     * @return bool
+     * @access public
+     */
+    private function precheck()
+    {
+        if (!($this->bitmap & SSH2::MASK_LOGIN)) {
+            return false;
+        }
+
+        if ($this->pwd === false) {
+            return $this->init_sftp_connection();
+        }
+
+        return true;
+    }
+
+    /**
+     * Partially initialize an SFTP connection
      *
-     * @param string $username
-     * @param string|AsymmetricKey|array[]|Agent|null ...$args
      * @throws \UnexpectedValueException on receipt of unexpected packets
      * @return bool
      * @access public
      */
-    public function login($username, ...$args)
+    private function partial_init_sftp_connection()
-    {
-        if (!parent::login(...func_get_args())) {
-            return false;
-        }
-
-        return $this->init_sftp_connection();
-    }
-
-    /**
-     * (Re)initializes the SFTP channel
-     *
-     * @throws \UnexpectedValueException on receipt of unexpected packets
-     * @return bool
-     * @access private
-     */
-    private function init_sftp_connection()
     {
         $this->window_size_server_to_client[self::CHANNEL] = $this->window_size;
 
@@ -548,27 +604,30 @@ class SFTP extends SSH2
                                               . 'Got packet type: ' . $this->packet_type);
         }
 
-        list($this->version) = Strings::unpackSSH2('N', $response);
+        $this->use_request_id = true;
+
+        list($this->defaultVersion) = Strings::unpackSSH2('N', $response);
         while (!empty($response)) {
             list($key, $value) = Strings::unpackSSH2('ss', $response);
             $this->extensions[$key] = $value;
         }
 
-        /*
+        $this->partial_init = true;
-         SFTPv4+ defines a 'newline' extension.  SFTPv3 seems to have unofficial support for it via 'newline@vandyke.com',
-         however, I'm not sure what 'newline@vandyke.com' is supposed to do (the fact that it's unofficial means that it's
-         not in the official SFTPv3 specs) and 'newline@vandyke.com' / 'newline' are likely not drop-in substitutes for
-         one another due to the fact that 'newline' comes with a SSH_FXF_TEXT bitmask whereas it seems unlikely that
-         'newline@vandyke.com' would.
-        */
-        /*
-        if (isset($this->extensions['newline@vandyke.com'])) {
-            $this->extensions['newline'] = $this->extensions['newline@vandyke.com'];
-            unset($this->extensions['newline@vandyke.com']);
-        }
-        */
 
-        $this->use_request_id = true;
+        return true;
+    }
+
+    /**
+     * (Re)initializes the SFTP channel
+     *
+     * @return bool
+     * @access private
+     */
+    private function init_sftp_connection()
+    {
+        if (!$this->partial_init && !$this->partial_init_sftp_connection()) {
+            return false;
+        }
 
         /*
          A Note on SFTPv4/5/6 support:
@@ -593,14 +652,56 @@ class SFTP extends SSH2
          in draft-ietf-secsh-filexfer-13 would be quite impossible.  As such, what \phpseclib3\Net\SFTP would do is close the
          channel and reopen it with a new and updated SSH_FXP_INIT packet.
         */
-        switch ($this->version) {
+        $this->version = $this->defaultVersion;
-            case 2:
+        if (isset($this->extensions['versions']) && (!$this->preferredVersion || $this->preferredVersion != $this->version)) {
-            case 3:
+            $versions = explode(',', $this->extensions['versions']);
+            $supported = [6, 5, 4];
+            if ($this->preferredVersion) {
+                $supported = array_diff($supported, [$this->preferredVersion]);
+                array_unshift($supported, $this->preferredVersion);
+            }
+            foreach ($supported as $ver) {
+                if (in_array($ver, $versions)) {
+                    if ($ver === $this->version) {
                         break;
-            default:
+                    }
+                    $this->version = (int) $ver;
+                    $packet = Strings::packSSH2('ss', 'version-select', "$ver");
+                    $this->send_sftp_packet(NET_SFTP_EXTENDED, $packet);
+                    $response = $this->get_sftp_packet();
+                    if ($this->packet_type != NET_SFTP_STATUS) {
+                        throw new \UnexpectedValueException('Expected NET_SFTP_STATUS. '
+                            . 'Got packet type: ' . $this->packet_type);
+                    }
+                    list($status) = Strings::unpackSSH2('N', $response);
+                    if ($status != NET_SFTP_STATUS_OK) {
+                        $this->logError($response, $status);
+                        throw new \UnexpectedValueException('Expected NET_SFTP_STATUS_OK. '
+                            . ' Got ' . $status);
+                    }
+                    break;
+                }
+            }
+        }
+
+        /*
+         SFTPv4+ defines a 'newline' extension.  SFTPv3 seems to have unofficial support for it via 'newline@vandyke.com',
+         however, I'm not sure what 'newline@vandyke.com' is supposed to do (the fact that it's unofficial means that it's
+         not in the official SFTPv3 specs) and 'newline@vandyke.com' / 'newline' are likely not drop-in substitutes for
+         one another due to the fact that 'newline' comes with a SSH_FXF_TEXT bitmask whereas it seems unlikely that
+         'newline@vandyke.com' would.
+        */
+        /*
+        if (isset($this->extensions['newline@vandyke.com'])) {
+            $this->extensions['newline'] = $this->extensions['newline@vandyke.com'];
+            unset($this->extensions['newline@vandyke.com']);
+        }
+        */
+        if ($this->version < 2 || $this->version > 6) {
             return false;
         }
 
+        $this->pwd = true;
         $this->pwd = $this->realpath('.');
 
         $this->update_stat_cache($this->pwd, []);
@@ -686,6 +787,10 @@ class SFTP extends SSH2
      */
     public function pwd()
     {
+        if (!$this->precheck()) {
+            return false;
+        }
+
         return $this->pwd;
     }
 
@@ -729,11 +834,15 @@ class SFTP extends SSH2
      */
     public function realpath($path)
     {
+        if ($this->precheck() === false) {
+            return false;
+        }
+
         if (!$this->canonicalize_paths) {
             return $path;
         }
 
-        if ($this->pwd === false) {
+        if ($this->pwd === true) {
             // http://tools.ietf.org/html/draft-ietf-secsh-filexfer-13#section-8.9
             $this->send_sftp_packet(NET_SFTP_REALPATH, Strings::packSSH2('s', $path));
 
@@ -787,7 +896,7 @@ class SFTP extends SSH2
      */
     public function chdir($dir)
     {
-        if (!($this->bitmap & SSH2::MASK_LOGIN)) {
+        if (!$this->precheck()) {
             return false;
         }
 
@@ -941,7 +1050,7 @@ class SFTP extends SSH2
      */
     private function readlist($dir, $raw = true)
     {
-        if (!($this->bitmap & SSH2::MASK_LOGIN)) {
+        if (!$this->precheck()) {
             return false;
         }
 
@@ -984,9 +1093,14 @@ class SFTP extends SSH2
                 case NET_SFTP_NAME:
                     list($count) = Strings::unpackSSH2('N', $response);
                     for ($i = 0; $i < $count; $i++) {
-                        list($shortname, $longname) = Strings::unpackSSH2('ss', $response);
+                        list($shortname) = Strings::unpackSSH2('s', $response);
+                        // SFTPv4 "removed the long filename from the names structure-- it can now be
+                        //         built from information available in the attrs structure."
+                        if ($this->version < 4) {
+                            list($longname) = Strings::unpackSSH2('s', $response);
+                        }
                         $attributes = $this->parseAttributes($response);
-                        if (!isset($attributes['type'])) {
+                        if (!isset($attributes['type']) && $this->version < 4) {
                             $fileType = $this->parseLongname($longname);
                             if ($fileType) {
                                 $attributes['type'] = $fileType;
@@ -1240,7 +1354,7 @@ class SFTP extends SSH2
      */
     public function stat($filename)
     {
-        if (!($this->bitmap & SSH2::MASK_LOGIN)) {
+        if (!$this->precheck()) {
             return false;
         }
 
@@ -1297,7 +1411,7 @@ class SFTP extends SSH2
      */
     public function lstat($filename)
     {
-        if (!($this->bitmap & SSH2::MASK_LOGIN)) {
+        if (!$this->precheck()) {
             return false;
         }
 
@@ -1392,7 +1506,7 @@ class SFTP extends SSH2
      */
     public function truncate($filename, $new_size)
     {
-        $attr = pack('N3', NET_SFTP_ATTR_SIZE, $new_size / 4294967296, $new_size); // 4294967296 == 0x100000000 == 1<<32
+        $attr = Strings::packSSH2('NQ', NET_SFTP_ATTR_SIZE, $new_size);
 
         return $this->setstat($filename, $attr, false);
     }
@@ -1411,7 +1525,7 @@ class SFTP extends SSH2
      */
     public function touch($filename, $time = null, $atime = null)
     {
-        if (!($this->bitmap & SSH2::MASK_LOGIN)) {
+        if (!$this->precheck()) {
             return false;
         }
 
@@ -1427,9 +1541,16 @@ class SFTP extends SSH2
             $atime = $time;
         }
 
-        $flags = NET_SFTP_OPEN_WRITE | NET_SFTP_OPEN_CREATE | NET_SFTP_OPEN_EXCL;
+        $attr = $this->version < 4 ?
-        $attr = pack('N3', NET_SFTP_ATTR_ACCESSTIME, $time, $atime);
+            pack('N3', NET_SFTP_ATTR_ACCESSTIME, $atime, $time) :
-        $packet = Strings::packSSH2('sN', $filename, $flags) . $attr;
+            Strings::packSSH2('NQ2', NET_SFTP_ATTR_ACCESSTIME | NET_SFTP_ATTR_MODIFYTIME, $atime, $time);
+
+        $packet = Strings::packSSH2('s', $filename);
+        $packet.= $this->version >= 5 ?
+            pack('N2', 0, NET_SFTP_OPEN_OPEN_EXISTING) :
+            pack('N', NET_SFTP_OPEN_WRITE | NET_SFTP_OPEN_CREATE | NET_SFTP_OPEN_EXCL);
+        $packet.= $attr;
+
         $this->send_sftp_packet(NET_SFTP_OPEN, $packet);
 
         $response = $this->get_sftp_packet();
@@ -1450,19 +1571,47 @@ class SFTP extends SSH2
     /**
      * Changes file or directory owner
      *
+     * $uid should be an int for SFTPv3 and a string for SFTPv4+. Ideally the string
+     * would be of the form "user@dns_domain" but it does not need to be.
+     * `$sftp->getSupportedVersions()['version']` will return the specific version
+     * that's being used.
+     *
      * Returns true on success or false on error.
      *
      * @param string $filename
-     * @param int $uid
+     * @param int|string $uid
      * @param bool $recursive
      * @return bool
      * @access public
      */
     public function chown($filename, $uid, $recursive = false)
     {
-        // quoting from <http://www.kernel.org/doc/man-pages/online/pages/man2/chown.2.html>,
+        /*
+         quoting <https://datatracker.ietf.org/doc/html/draft-ietf-secsh-filexfer-13#section-7.5>,
+
+         "To avoid a representation that is tied to a particular underlying
+          implementation at the client or server, the use of UTF-8 strings has
+          been chosen.  The string should be of the form "user@dns_domain".
+          This will allow for a client and server that do not use the same
+          local representation the ability to translate to a common syntax that
+          can be interpreted by both.  In the case where there is no
+          translation available to the client or server, the attribute value
+          must be constructed without the "@"."
+
+         phpseclib _could_ auto append the dns_domain to $uid BUT what if it shouldn't
+         have one? phpseclib would have no way of knowing so rather than guess phpseclib
+         will just use whatever value the user provided
+       */
+
+        $attr = $this->version < 4 ?
+            // quoting <http://www.kernel.org/doc/man-pages/online/pages/man2/chown.2.html>,
             // "if the owner or group is specified as -1, then that ID is not changed"
-        $attr = pack('N3', NET_SFTP_ATTR_UIDGID, $uid, -1);
+            pack('N3', NET_SFTP_ATTR_UIDGID, $uid, -1) :
+            // quoting <https://datatracker.ietf.org/doc/html/draft-ietf-secsh-filexfer-13#section-7.5>,
+            // "If either the owner or group field is zero length, the field should be
+            //  considered absent, and no change should be made to that specific field
+            //  during a modification operation"
+            Strings::packSSH2('Nss', NET_SFTP_ATTR_OWNERGROUP, $uid, '');
 
         return $this->setstat($filename, $attr, $recursive);
     }
@@ -1470,17 +1619,24 @@ class SFTP extends SSH2
     /**
      * Changes file or directory group
      *
+     * $gid should be an int for SFTPv3 and a string for SFTPv4+. Ideally the string
+     * would be of the form "user@dns_domain" but it does not need to be.
+     * `$sftp->getSupportedVersions()['version']` will return the specific version
+     * that's being used.
+     *
      * Returns true on success or false on error.
      *
      * @param string $filename
-     * @param int $gid
+     * @param int|string $gid
      * @param bool $recursive
      * @return bool
      * @access public
      */
     public function chgrp($filename, $gid, $recursive = false)
     {
-        $attr = pack('N3', NET_SFTP_ATTR_UIDGID, -1, $gid);
+        $attr = $this->version < 4 ?
+            pack('N3', NET_SFTP_ATTR_UIDGID, $gid, -1) :
+            Strings::packSSH2('Nss', NET_SFTP_ATTR_OWNERGROUP, '', $gid);
 
         return $this->setstat($filename, $attr, $recursive);
     }
@@ -1547,7 +1703,7 @@ class SFTP extends SSH2
      */
     private function setstat($filename, $attr, $recursive)
     {
-        if (!($this->bitmap & SSH2::MASK_LOGIN)) {
+        if (!$this->precheck()) {
             return false;
         }
 
@@ -1565,9 +1721,11 @@ class SFTP extends SSH2
             return $result;
         }
 
-        // SFTPv4+ has an additional byte field - type - that would need to be sent, as well. setting it to
+        $packet = Strings::packSSH2('s', $filename);
-        // SSH_FILEXFER_TYPE_UNKNOWN might work. if not, we'd have to do an SSH_FXP_STAT before doing an SSH_FXP_SETSTAT.
+        $packet.= $this->version >= 4 ?
-        $this->send_sftp_packet(NET_SFTP_SETSTAT, Strings::packSSH2('s', $filename) . $attr);
+            pack('a*Ca*', substr($attr, 0, 4), NET_SFTP_TYPE_UNKNOWN, substr($attr, 4)) :
+            $attr;
+        $this->send_sftp_packet(NET_SFTP_SETSTAT, $packet);
 
         /*
          "Because some systems must use separate system calls to set various attributes, it is possible that a failure
@@ -1632,7 +1790,11 @@ class SFTP extends SSH2
                     return false;
                 }
             } else {
-                $this->send_sftp_packet(NET_SFTP_SETSTAT, Strings::packSSH2('s', $temp) . $attr);
+                $packet = Strings::packSSH2('s', $temp);
+                $packet.= $this->version >= 4 ?
+                    pack('Ca*', NET_SFTP_TYPE_UNKNOWN, $attr) :
+                    $attr;
+                $this->send_sftp_packet(NET_SFTP_SETSTAT, $packet);
 
                 $i++;
 
@@ -1645,7 +1807,11 @@ class SFTP extends SSH2
             }
         }
 
-        $this->send_sftp_packet(NET_SFTP_SETSTAT, Strings::packSSH2('s', $path) . $attr);
+        $packet = Strings::packSSH2('s', $path);
+        $packet.= $this->version >= 4 ?
+            pack('Ca*', NET_SFTP_TYPE_UNKNOWN, $attr) :
+            $atr;
+        $this->send_sftp_packet(NET_SFTP_SETSTAT, $packet);
 
         $i++;
 
@@ -1669,7 +1835,7 @@ class SFTP extends SSH2
      */
     public function readlink($link)
     {
-        if (!($this->bitmap & SSH2::MASK_LOGIN)) {
+        if (!$this->precheck()) {
             return false;
         }
 
@@ -1713,15 +1879,44 @@ class SFTP extends SSH2
      */
     public function symlink($target, $link)
     {
-        if (!($this->bitmap & SSH2::MASK_LOGIN)) {
+        if (!$this->precheck()) {
             return false;
         }
 
         //$target = $this->realpath($target);
         $link = $this->realpath($link);
 
-        $packet = Strings::packSSH2('ss', $target, $link);
+        /* quoting https://datatracker.ietf.org/doc/html/draft-ietf-secsh-filexfer-09#section-12.1 :
-        $this->send_sftp_packet(NET_SFTP_SYMLINK, $packet);
+
+           Changed the SYMLINK packet to be LINK and give it the ability to
+           create hard links.  Also change it's packet number because many
+           implementation implemented SYMLINK with the arguments reversed.
+           Hopefully the new argument names make it clear which way is which.
+        */
+        if ($this->version == 6) {
+            $type = NET_SFTP_LINK;
+            $packet = Strings::packSSH2('ssC', $link, $target, 1);
+        } else {
+            $type = NET_SFTP_SYMLINK;
+            /* quoting http://bxr.su/OpenBSD/usr.bin/ssh/PROTOCOL#347 :
+
+               3.1. sftp: Reversal of arguments to SSH_FXP_SYMLINK
+
+               When OpenSSH's sftp-server was implemented, the order of the arguments
+               to the SSH_FXP_SYMLINK method was inadvertently reversed. Unfortunately,
+               the reversal was not noticed until the server was widely deployed. Since
+               fixing this to follow the specification would cause incompatibility, the
+               current order was retained. For correct operation, clients should send
+               SSH_FXP_SYMLINK as follows:
+
+                   uint32      id
+                   string      targetpath
+                   string      linkpath */
+            $packet = substr($this->server_identifier, 0, 15) == 'SSH-2.0-OpenSSH' ?
+                Strings::packSSH2('ss', $target, $link) :
+                Strings::packSSH2('ss', $link, $target);
+        }
+        $this->send_sftp_packet($type, $packet);
 
         $response = $this->get_sftp_packet();
         if ($this->packet_type != NET_SFTP_STATUS) {
@@ -1749,7 +1944,7 @@ class SFTP extends SSH2
      */
     public function mkdir($dir, $mode = -1, $recursive = false)
     {
-        if (!($this->bitmap & SSH2::MASK_LOGIN)) {
+        if (!$this->precheck()) {
             return false;
         }
 
@@ -1814,7 +2009,7 @@ class SFTP extends SSH2
      */
     public function rmdir($dir)
     {
-        if (!($this->bitmap & SSH2::MASK_LOGIN)) {
+        if (!$this->precheck()) {
             return false;
         }
 
@@ -1858,7 +2053,8 @@ class SFTP extends SSH2
      * contain as many bytes as filename.ext does on your local filesystem.  If your filename.ext is 1MB then that is how
      * large $remote_file will be, as well.
      *
-     * Setting $mode to self::SOURCE_CALLBACK will use $data as callback function, which gets only one parameter -- number of bytes to return, and returns a string if there is some data or null if there is no more data
+     * Setting $mode to self::SOURCE_CALLBACK will use $data as callback function, which gets only one parameter -- number
+     * of bytes to return, and returns a string if there is some data or null if there is no more data
      *
      * If $data is a resource then it'll be used as a resource instead.
      *
@@ -1898,7 +2094,7 @@ class SFTP extends SSH2
      */
     public function put($remote_file, $data, $mode = self::SOURCE_STRING, $start = -1, $local_start = -1, $progressCallback = null)
     {
-        if (!($this->bitmap & SSH2::MASK_LOGIN)) {
+        if (!$this->precheck()) {
             return false;
         }
 
@@ -1907,10 +2103,16 @@ class SFTP extends SSH2
             return false;
         }
 
+        $this->remove_from_stat_cache($remote_file);
+
+        if ($this->version >= 5) {
+            $flags = NET_SFTP_OPEN_OPEN_OR_CREATE;
+        } else {
             $flags = NET_SFTP_OPEN_WRITE | NET_SFTP_OPEN_CREATE;
             // according to the SFTP specs, NET_SFTP_OPEN_APPEND should "force all writes to append data at the end of the file."
             // in practice, it doesn't seem to do that.
             //$flags|= ($mode & self::RESUME) ? NET_SFTP_OPEN_APPEND : NET_SFTP_OPEN_TRUNCATE;
+        }
 
         if ($start >= 0) {
             $offset = $start;
@@ -1920,12 +2122,19 @@ class SFTP extends SSH2
             $offset = $size !== false ? $size : 0;
         } else {
             $offset = 0;
+            if ($this->version >= 5) {
+                $flags = NET_SFTP_OPEN_CREATE_TRUNCATE;
+            } else {
                 $flags|= NET_SFTP_OPEN_TRUNCATE;
             }
+        }
 
         $this->remove_from_stat_cache($remote_file);
 
-        $packet = Strings::packSSH2('sNN', $remote_file, $flags, 0);
+        $packet = Strings::packSSH2('s', $remote_file);
+        $packet.= $this->version >= 5 ?
+            pack('N3', 0, $flags, 0) :
+            pack('N2', $flags, 0);
         $this->send_sftp_packet(NET_SFTP_OPEN, $packet);
 
         $response = $this->get_sftp_packet();
@@ -2032,6 +2241,8 @@ class SFTP extends SSH2
             }
         }
 
+        $result = $this->close_handle($handle);
+
         if (!$this->read_put_responses($i)) {
             if ($mode & self::SOURCE_LOCAL_FILE) {
                 fclose($fp);
@@ -2040,18 +2251,23 @@ class SFTP extends SSH2
             return false;
         }
 
-        if ($mode & self::SOURCE_LOCAL_FILE) {
+        if ($mode & SFTP::SOURCE_LOCAL_FILE) {
-            if ($this->preserveTime) {
-                $stat = fstat($fp);
-                $this->touch($remote_file, $stat['mtime'], $stat['atime']);
-            }
-
             if (isset($fp) && is_resource($fp)) {
                 fclose($fp);
             }
+
+            if ($this->preserveTime) {
+                $stat = stat($data);
+                $attr = $this->version < 4 ?
+                    pack('N3', NET_SFTP_ATTR_ACCESSTIME, $stat['atime'], $stat['time']) :
+                    Strings::packSSH2('NQ2', NET_SFTP_ATTR_ACCESSTIME | NET_SFTP_ATTR_MODIFYTIME, $stat['atime'], $stat['time']);
+                if (!$this->setstat($remote_file, $attr, false)) {
+                    throw new \RuntimeException('Error setting file time');
+                }
+            }
         }
 
-        return $this->close_handle($handle);
+        return $result;
     }
 
     /**
@@ -2133,7 +2349,7 @@ class SFTP extends SSH2
      */
     public function get($remote_file, $local_file = false, $offset = 0, $length = -1, $progressCallback = null)
     {
-        if (!($this->bitmap & SSH2::MASK_LOGIN)) {
+        if (!$this->precheck()) {
             return false;
         }
 
@@ -2142,7 +2358,10 @@ class SFTP extends SSH2
             return false;
         }
 
-        $packet = pack('Na*N2', strlen($remote_file), $remote_file, NET_SFTP_OPEN_READ, 0);
+        $packet = Strings::packSSH2('s', $remote_file);
+        $packet.= $this->version >= 5 ?
+            pack('N3', 0, NET_SFTP_OPEN_OPEN_EXISTING, 0) :
+            pack('N2', NET_SFTP_OPEN_READ, 0);
         $this->send_sftp_packet(NET_SFTP_OPEN, $packet);
 
         $response = $this->get_sftp_packet();
@@ -2243,6 +2462,7 @@ class SFTP extends SSH2
                             fclose($fp);
                         }
                         if ($this->channel_close) {
+                            $this->partial_init = false;
                             $this->init_sftp_connection();
                             return false;
                         } else {
@@ -2294,7 +2514,7 @@ class SFTP extends SSH2
      */
     public function delete($path, $recursive = true)
     {
-        if (!($this->bitmap & SSH2::MASK_LOGIN)) {
+        if (!$this->precheck()) {
             return false;
         }
 
@@ -2415,6 +2635,10 @@ class SFTP extends SSH2
     public function file_exists($path)
     {
         if ($this->use_stat_cache) {
+            if (!$this->precheck()) {
+                return false;
+            }
+
             $path = $this->realpath($path);
 
             $result = $this->query_stat_cache($path);
@@ -2485,6 +2709,10 @@ class SFTP extends SSH2
      */
     public function is_readable($path)
     {
+        if (!$this->precheck()) {
+            return false;
+        }
+
         $packet = Strings::packSSH2('sNN', $this->realpath($path), NET_SFTP_OPEN_READ, 0);
         $this->send_sftp_packet(NET_SFTP_OPEN, $packet);
 
@@ -2509,6 +2737,10 @@ class SFTP extends SSH2
      */
     public function is_writable($path)
     {
+        if (!$this->precheck()) {
+            return false;
+        }
+
         $packet = Strings::packSSH2('sNN', $this->realpath($path), NET_SFTP_OPEN_WRITE, 0);
         $this->send_sftp_packet(NET_SFTP_OPEN, $packet);
 
@@ -2685,6 +2917,10 @@ class SFTP extends SSH2
      */
     private function get_xstat_cache_prop($path, $prop, $type)
     {
+        if (!$this->precheck()) {
+            return false;
+        }
+
         if ($this->use_stat_cache) {
             $path = $this->realpath($path);
 
@@ -2705,7 +2941,9 @@ class SFTP extends SSH2
     }
 
     /**
-     * Renames a file or a directory on the SFTP server
+     * Renames a file or a directory on the SFTP server.
+     *
+     * If the file already exists this will return false
      *
      * @param string $oldname
      * @param string $newname
@@ -2715,7 +2953,7 @@ class SFTP extends SSH2
      */
     public function rename($oldname, $newname)
     {
-        if (!($this->bitmap & SSH2::MASK_LOGIN)) {
+        if (!$this->precheck()) {
             return false;
         }
 
@@ -2727,6 +2965,18 @@ class SFTP extends SSH2
 
         // http://tools.ietf.org/html/draft-ietf-secsh-filexfer-13#section-8.3
         $packet = Strings::packSSH2('ss', $oldname, $newname);
+        if ($this->version >= 5) {
+            /* quoting https://datatracker.ietf.org/doc/html/draft-ietf-secsh-filexfer-05#section-6.5 ,
+
+               'flags' is 0 or a combination of:
+
+                   SSH_FXP_RENAME_OVERWRITE  0x00000001
+                   SSH_FXP_RENAME_ATOMIC     0x00000002
+                   SSH_FXP_RENAME_NATIVE     0x00000004
+
+               (none of these are currently supported) */
+            $packet.= "\0\0\0\0";
+        }
         $this->send_sftp_packet(NET_SFTP_RENAME, $packet);
 
         $response = $this->get_sftp_packet();
@@ -2751,6 +3001,27 @@ class SFTP extends SSH2
         return true;
     }
 
+    /**
+     * Parse Time
+     *
+     * See '7.7.  Times' of draft-ietf-secsh-filexfer-13 for more info.
+     *
+     * @param string $key
+     * @param int $flags
+     * @param string $response
+     * @return array
+     * @access private
+     */
+    private function parseTime($key, $flags, &$response)
+    {
+        $attr = [];
+        list($attr[$key]) = Strings::unpackSSH2('Q', $response);
+        if ($flags & NET_SFTP_ATTR_SUBSECOND_TIMES) {
+            list($attr[key . '-nseconds']) = Strings::unpackSSH2('N', $response);
+        }
+        return $attr;
+    }
+
     /**
      * Parse Attributes
      *
@@ -2762,10 +3033,12 @@ class SFTP extends SSH2
      */
     protected function parseAttributes(&$response)
     {
-        $attr = [];
+        if ($this->version >= 4) {
+            list($flags, $attr['type']) = Strings::unpackSSH2('NC', $response);
+        } else {
             list($flags) = Strings::unpackSSH2('N', $response);
+        }
 
-        // SFTPv4+ have a type field (a byte) that follows the above flag field
         foreach ($this->attributes as $key => $value) {
             switch ($flags & $key) {
                 case NET_SFTP_ATTR_SIZE:             // 0x00000001
@@ -2775,9 +3048,7 @@ class SFTP extends SSH2
                     // IEEE 754 binary64 "double precision" on such platforms and
                     // as such can represent integers of at least 2^50 without loss
                     // of precision. Interpreted in filesize, 2^50 bytes = 1024 TiB.
-                    list($upper, $size) = Strings::unpackSSH2('NN', $response);
+                    list($attr['size']) = Strings::unpackSSH2('Q', $response);
-                    $attr['size'] = $upper ? 4294967296 * $upper : 0;
-                    $attr['size']+= $size < 0 ? ($size & 0x7FFFFFFF) + 0x80000000 : $size;
                     break;
                 case NET_SFTP_ATTR_UIDGID: // 0x00000002 (SFTPv3 only)
                     list($attr['uid'], $attr['gid']) = Strings::unpackSSH2('NN', $response);
@@ -2785,13 +3056,78 @@ class SFTP extends SSH2
                 case NET_SFTP_ATTR_PERMISSIONS: // 0x00000004
                     list($attr['mode']) = Strings::unpackSSH2('N', $response);
                     $fileType = $this->parseMode($attr['mode']);
-                    if ($fileType !== false) {
+                    if ($this->version < 4 && $fileType !== false) {
                         $attr+= ['type' => $fileType];
                     }
                     break;
                 case NET_SFTP_ATTR_ACCESSTIME: // 0x00000008
+                    if ($this->version >= 4) {
+                        $attr+= $this->parseTime('atime', $flags, $response);
+                        break;
+                    }
                     list($attr['atime'], $attr['mtime']) = Strings::unpackSSH2('NN', $response);
                     break;
+                case NET_SFTP_ATTR_CREATETIME:       // 0x00000010 (SFTPv4+)
+                    $attr+= $this->parseTime('createtime', $flags, $response);
+                    break;
+                case NET_SFTP_ATTR_MODIFYTIME:       // 0x00000020
+                    $attr+= $this->parseTime('mtime', $flags, $response);
+                    break;
+                case NET_SFTP_ATTR_ACL:              // 0x00000040
+                    // access control list
+                    // see https://datatracker.ietf.org/doc/html/draft-ietf-secsh-filexfer-04#section-5.7
+                    // currently unsupported
+                    list($count) = Strings::unpackSSH2('N', $response);
+                    for ($i = 0; $i < $count; $i++) {
+                        list($type, $flag, $mask, $who) = Strings::unpackSSH2('N3s', $result);
+                    }
+                    break;
+                case NET_SFTP_ATTR_OWNERGROUP:       // 0x00000080
+                    list($attr['owner'], $attr['$group']) = Strings::unpackSSH2('ss', $response);
+                    break;
+                case NET_SFTP_ATTR_SUBSECOND_TIMES:  // 0x00000100
+                    break;
+                case NET_SFTP_ATTR_BITS:             // 0x00000200 (SFTPv5+)
+                    // see https://datatracker.ietf.org/doc/html/draft-ietf-secsh-filexfer-05#section-5.8
+                    // currently unsupported
+                    // tells if you file is:
+                    // readonly, system, hidden, case inensitive, archive, encrypted, compressed, sparse
+                    // append only, immutable, sync
+                    list($attrib_bits, $attrib_bits_valid) = Strings::unpackSSH2('N2', $response);
+                    // if we were actually gonna implement the above it ought to be
+                    // $attr['attrib-bits'] and $attr['attrib-bits-valid']
+                    // eg. - instead of _
+                    break;
+                case NET_SFTP_ATTR_ALLOCATION_SIZE:  // 0x00000400 (SFTPv6+)
+                    // see https://datatracker.ietf.org/doc/html/draft-ietf-secsh-filexfer-13#section-7.4
+                    // represents the number of bytes that the file consumes on the disk. will
+                    // usually be larger than the 'size' field
+                    list($attr['allocation-size']) = Strings::unpack('Q', $response);
+                    break;
+                case NET_SFTP_ATTR_TEXT_HINT:        // 0x00000800
+                    // https://datatracker.ietf.org/doc/html/draft-ietf-secsh-filexfer-13#section-7.10
+                    // currently unsupported
+                    // tells if file is "known text", "guessed text", "known binary", "guessed binary"
+                    list($text_hint) = Strings::unpackSSH2('C', $response);
+                    // the above should be $attr['text-hint']
+                    break;
+                case NET_SFTP_ATTR_MIME_TYPE:        // 0x00001000
+                    // see https://datatracker.ietf.org/doc/html/draft-ietf-secsh-filexfer-13#section-7.11
+                    list($attr['mime-type']) = Strings::unpackSSH2('s', $response);
+                    break;
+                case NET_SFTP_ATTR_LINK_COUNT:       // 0x00002000
+                    // see https://datatracker.ietf.org/doc/html/draft-ietf-secsh-filexfer-13#section-7.12
+                    list($attr['link-count']) = Strings::unpackSS2('N', $response);
+                    break;
+                case NET_SFTP_ATTR_UNTRANSLATED_NAME:// 0x00004000
+                    // see https://datatracker.ietf.org/doc/html/draft-ietf-secsh-filexfer-13#section-7.13
+                    list($attr['untranslated-name']) = Strings::unpackSSH2('s', $response);
+                    break;
+                case NET_SFTP_ATTR_CTIME:            // 0x00008000
+                    // 'ctime' contains the last time the file attributes were changed.  The
+                    // exact meaning of this field depends on the server.
+                    $attr+= $this->parseTime('ctime', $flags, $response);
+                    break;
                 case NET_SFTP_ATTR_EXTENDED: // 0x80000000
                     list($count) = Strings::unpackSSH2('N', $response);
                     for ($i = 0; $i < $count; $i++) {
@@ -3116,13 +3452,51 @@ class SFTP extends SSH2
      */
     public function getSupportedVersions()
     {
-        $temp = ['version' => $this->version];
+        if (!($this->bitmap & NET_SSH2_MASK_LOGIN)) {
+            return false;
+        }
+
+        if (!$this->partial_init) {
+            $this->partial_init_sftp_connection();
+        }
+
+        $temp = ['version' => $this->defaultVersion];
         if (isset($this->extensions['versions'])) {
             $temp['extensions'] = $this->extensions['versions'];
         }
         return $temp;
     }
 
+    /**
+     * Get supported SFTP versions
+     *
+     * @return array
+     * @access public
+     */
+    public function getNegotiatedVersion()
+    {
+        if (!$this->precheck()) {
+            return false;
+        }
+
+        return $this->version;
+    }
+
+    /**
+     * Set preferred version
+     *
+     * If you're preferred version isn't supported then the highest supported
+     * version of SFTP will be utilized. Set to null or false or int(0) to
+     * unset the preferred version
+     *
+     * @param int $version
+     * @access public
+     */
+    public function setPreferredVersion($version)
+    {
+        $this->preferredVersion = $version;
+    }
+
     /**
      * Disconnect
      *

phpseclib/Net/SSH2.php

@@ -216,7 +216,7 @@ class SSH2
      * @var array|false
      * @access private
      */
-    private $server_identifier = false;
+    protected $server_identifier = false;
 
     /**
      * Key Exchange Algorithms