Merge pull request #1898 from rposky/master

SSH2: Better support for multiple interactive channels & expose shell functions: 3.0 Backport Master Merge

phpseclib/Net/SSH2.php

@@ -549,6 +549,13 @@ class SSH2
      */
     protected array $channel_status = [];
 
+    /**
+     * The identifier of the interactive channel which was opened most recently
+     *
+     * @see self::getInteractiveChannelId()
+     */
+    private int $channel_id_last_interactive = 0;
+
     /**
      * Packet Size
      *
@@ -721,16 +728,6 @@ class SSH2
      */
     private bool $request_pty = false;
 
-    /**
-     * Flag set while exec() is running when using enablePTY()
-     */
-    private bool $in_request_pty_exec = false;
-
-    /**
-     * Flag set after startSubsystem() is called
-     */
-    private bool $in_subsystem = false;
-
     /**
      * Contents of stdError
      */
@@ -2431,7 +2428,7 @@ class SSH2
             return false;
         }
 
-        if ($this->in_request_pty_exec) {
+        if ($this->isPTYOpen()) {
             throw new RuntimeException('If you want to run multiple exec()\'s you will need to disable (and re-enable if appropriate) a PTY for each one.');
         }
 
@@ -2481,8 +2478,6 @@ class SSH2
                 $this->disconnect_helper(DisconnectReason::BY_APPLICATION);
                 throw new RuntimeException('Unable to request pseudo-terminal');
             }
-
-            $this->in_request_pty_exec = true;
         }
 
         // sending a pty-req SSH_MSG_CHANNEL_REQUEST message is unnecessary and, in fact, in most cases, slows things
@@ -2512,7 +2507,8 @@ class SSH2
 
         $this->channel_status[self::CHANNEL_EXEC] = MessageType::CHANNEL_DATA;
 
-        if ($this->in_request_pty_exec) {
+        if ($this->request_pty === true) {
+            $this->channel_id_last_interactive = self::CHANNEL_EXEC;
             return true;
         }
 
@@ -2540,15 +2536,24 @@ class SSH2
     /**
      * Creates an interactive shell
      *
+     * Returns bool(true) if the shell was opened.
+     * Returns bool(false) if the shell was already open.
+     *
+     * @throws InsufficientSetupException if not authenticated
      * @throws UnexpectedValueException on receipt of unexpected packets
      * @throws RuntimeException on other errors
-     *@see self::read()
+     * @see self::isShellOpen()
+     * @see self::read()
      * @see self::write()
      */
-    private function initShell(): bool
+    public function openShell(): bool
     {
-        if ($this->in_request_pty_exec === true) {
-            return true;
+        if ($this->isShellOpen()) {
+            return false;
+        }
+
+        if (!$this->isAuthenticated()) {
+            throw new InsufficientSetupException('Operation disallowed prior to login()');
         }
 
         $this->window_size_server_to_client[self::CHANNEL_SHELL] = $this->window_size;
@@ -2608,29 +2613,41 @@ class SSH2
 
         $this->channel_status[self::CHANNEL_SHELL] = MessageType::CHANNEL_DATA;
 
+        $this->channel_id_last_interactive = self::CHANNEL_SHELL;
+
         $this->bitmap |= self::MASK_SHELL;
 
         return true;
     }
 
     /**
-     * Return the channel to be used with read() / write()
-     *
+     * Return the channel to be used with read(), write(), and reset(), if none were specified
+     * @deprecated for lack of transparency in intended channel target, to be potentially replaced
+     *             with method which guarantees open-ness of all yielded channels and throws
+     *             error for multiple open channels
      * @see self::read()
      * @see self::write()
      */
     private function get_interactive_channel(): int
     {
         switch (true) {
-            case $this->in_subsystem:
+            case $this->is_channel_status_data(self::CHANNEL_SUBSYSTEM):
                 return self::CHANNEL_SUBSYSTEM;
-            case $this->in_request_pty_exec:
+            case $this->is_channel_status_data(self::CHANNEL_EXEC):
                 return self::CHANNEL_EXEC;
             default:
                 return self::CHANNEL_SHELL;
         }
     }
 
+    /**
+     * Indicates the DATA status on the given channel
+     */
+    private function is_channel_status_data(int $channel): bool
+    {
+        return isset($this->channel_status[$channel]) && $this->channel_status[$channel] == MessageType::CHANNEL_DATA;
+    }
+
     /**
      * Return an available open channel
      *
@@ -2685,24 +2702,36 @@ class SSH2
      * Returns when there's a match for $expect, which can take the form of a string literal or,
      * if $mode == self::READ_REGEX, a regular expression.
      *
+     * If not specifying a channel, an open interactive channel will be selected, or, if there are
+     * no open channels, an interactive shell will be created. If there are multiple open
+     * interactive channels, a legacy behavior will apply in which channel selection prioritizes
+     * an active subsystem, the exec pty, and, lastly, the shell. If using multiple interactive
+     * channels, callers are discouraged from relying on this legacy behavior and should specify
+     * the intended channel.
+     *
+     * @param int $mode One of the self::READ_* constants
+     * @param int|null $channel Channel id returned by self::getInteractiveChannelId()
      * @return string|bool|null
      * @throws RuntimeException on connection error
+     * @throws InsufficientSetupException on unexpected channel status, possibly due to closure
      * @see self::write()
      */
-    public function read(string $expect = '', int $mode = self::READ_SIMPLE)
+    public function read(string $expect = '', int $mode = self::READ_SIMPLE, int $channel = null)
     {
         $this->curTimeout = $this->timeout;
         $this->is_timeout = false;
 
-        if (!$this->isAuthenticated()) {
-            throw new InsufficientSetupException('Operation disallowed prior to login()');
+        if ($channel === null) {
+            $channel = $this->get_interactive_channel();
         }
 
-        if (!($this->bitmap & self::MASK_SHELL) && !$this->initShell()) {
+        if (!$this->isInteractiveChannelOpen($channel)) {
+            if ($channel != self::CHANNEL_SHELL) {
+                throw new InsufficientSetupException('Data is not available on channel');
+            } elseif (!$this->openShell()) {
                 throw new RuntimeException('Unable to initiate an interactive shell session');
             }
-
-        $channel = $this->get_interactive_channel();
+        }
 
         if ($mode == self::READ_NEXT) {
             return $this->get_channel_packet($channel);
@@ -2720,7 +2749,6 @@ class SSH2
             }
             $response = $this->get_channel_packet($channel);
             if ($response === true) {
-                $this->in_request_pty_exec = false;
                 return Strings::shift($this->interactiveBuffer, strlen($this->interactiveBuffer));
             }
 
@@ -2731,20 +2759,33 @@ class SSH2
     /**
      * Inputs a command into an interactive shell.
      *
+     * If not specifying a channel, an open interactive channel will be selected, or, if there are
+     * no open channels, an interactive shell will be created. If there are multiple open
+     * interactive channels, a legacy behavior will apply in which channel selection prioritizes
+     * an active subsystem, the exec pty, and, lastly, the shell. If using multiple interactive
+     * channels, callers are discouraged from relying on this legacy behavior and should specify
+     * the intended channel.
+     *
+     * @param int|null $channel Channel id returned by self::getInteractiveChannelId()
      * @throws RuntimeException on connection error
+     * @throws InsufficientSetupException on unexpected channel status, possibly due to closure
      * @see SSH2::read()
      */
-    public function write(string $cmd): void
+    public function write(string $cmd, int $channel = null): void
     {
-        if (!$this->isAuthenticated()) {
-            throw new InsufficientSetupException('Operation disallowed prior to login()');
+        if ($channel === null) {
+            $channel = $this->get_interactive_channel();
         }
 
-        if (!($this->bitmap & self::MASK_SHELL) && !$this->initShell()) {
+        if (!$this->isInteractiveChannelOpen($channel)) {
+            if ($channel != self::CHANNEL_SHELL) {
+                throw new InsufficientSetupException('Data is not available on channel');
+            } elseif (!$this->openShell()) {
                 throw new RuntimeException('Unable to initiate an interactive shell session');
             }
+        }
 
-        $this->send_channel_packet($this->get_interactive_channel(), $cmd);
+        $this->send_channel_packet($channel, $cmd);
     }
 
     /**
@@ -2795,8 +2836,7 @@ class SSH2
 
         $this->channel_status[self::CHANNEL_SUBSYSTEM] = MessageType::CHANNEL_DATA;
 
-        $this->bitmap |= self::MASK_SHELL;
-        $this->in_subsystem = true;
+        $this->channel_id_last_interactive = self::CHANNEL_SUBSYSTEM;
 
         return true;
     }
@@ -2808,8 +2848,9 @@ class SSH2
      */
     public function stopSubsystem(): bool
     {
-        $this->in_subsystem = false;
+        if ($this->isInteractiveChannelOpen(self::CHANNEL_SUBSYSTEM)) {
             $this->close_channel(self::CHANNEL_SUBSYSTEM);
+        }
         return true;
     }
 
@@ -2817,10 +2858,23 @@ class SSH2
      * Closes a channel
      *
      * If read() timed out you might want to just close the channel and have it auto-restart on the next read() call
+     *
+     * If not specifying a channel, an open interactive channel will be selected. If there are
+     * multiple open interactive channels, a legacy behavior will apply in which channel selection
+     * prioritizes an active subsystem, the exec pty, and, lastly, the shell. If using multiple
+     * interactive channels, callers are discouraged from relying on this legacy behavior and
+     * should specify the intended channel.
+     *
+     * @param int|null $channel Channel id returned by self::getInteractiveChannelId()
      */
-    public function reset(): void
+    public function reset(int $channel = null): void
     {
-        $this->close_channel($this->get_interactive_channel());
+        if ($channel === null) {
+            $channel = $this->get_interactive_channel();
+        }
+        if ($this->isInteractiveChannelOpen($channel)) {
+            $this->close_channel($channel);
+        }
     }
 
     /**
@@ -2872,6 +2926,43 @@ class SSH2
         return (bool) ($this->bitmap & self::MASK_LOGIN);
     }
 
+    /**
+     * Is the interactive shell active?
+     */
+    public function isShellOpen(): bool
+    {
+        return $this->isInteractiveChannelOpen(self::CHANNEL_SHELL);
+    }
+
+    /**
+     * Is the exec pty active?
+     */
+    public function isPTYOpen(): bool
+    {
+        return $this->isInteractiveChannelOpen(self::CHANNEL_EXEC);
+    }
+
+    /**
+     * Is the given interactive channel active?
+     *
+     * @param int $channel Channel id returned by self::getInteractiveChannelId()
+     */
+    public function isInteractiveChannelOpen(int $channel): bool
+    {
+        return $this->isAuthenticated() && $this->is_channel_status_data($channel);
+    }
+
+    /**
+     * Returns a channel identifier, presently of the last interactive channel opened, regardless of current status.
+     * Returns 0 if no interactive channel has been opened.
+     *
+     * @see self::isInteractiveChannelOpen()
+     */
+    public function getInteractiveChannelId(): int
+    {
+        return $this->channel_id_last_interactive;
+    }
+
     /**
      * Pings a server connection, or tries to reconnect if the connection has gone down
      *
@@ -3448,9 +3539,8 @@ class SSH2
      */
     public function disablePTY(): void
     {
-        if ($this->in_request_pty_exec) {
+        if ($this->isPTYOpen()) {
             $this->close_channel(self::CHANNEL_EXEC);
-            $this->in_request_pty_exec = false;
         }
         $this->request_pty = false;
     }
@@ -3475,6 +3565,7 @@ class SSH2
      * - if the connection times out
      * - if the channel status is CHANNEL_OPEN and the response was CHANNEL_OPEN_CONFIRMATION
      * - if the channel status is CHANNEL_REQUEST and the response was CHANNEL_SUCCESS
+     * - if the channel status is CHANNEL_CLOSE and the response was CHANNEL_CLOSE
      *
      * bool(false) is returned if:
      *
@@ -3639,7 +3730,10 @@ class SSH2
                                 throw new RuntimeException('Unable to fulfill channel request');
                         }
                     case MessageType::CHANNEL_CLOSE:
-                        return $type == MessageType::CHANNEL_CLOSE ? true : $this->get_channel_packet($client_channel, $skip_extended);
+                        if ($client_channel == $channel && $type == MessageType::CHANNEL_CLOSE) {
+                            return true;
+                        }
+                        return $this->get_channel_packet($client_channel, $skip_extended);
                 }
             }
 
@@ -3674,9 +3768,8 @@ class SSH2
                 case MessageType::CHANNEL_CLOSE:
                     $this->curTimeout = 5;
 
-                    if ($this->bitmap & self::MASK_SHELL) {
-                        $this->bitmap &= ~self::MASK_SHELL;
-                    }
+                    $this->close_channel_bitmap($channel);
+
                     if ($this->channel_status[$channel] != MessageType::CHANNEL_EOF) {
                         $this->send_binary_packet(pack('CN', MessageType::CHANNEL_CLOSE, $this->server_channels[$channel]));
                     }
@@ -4002,17 +4095,27 @@ class SSH2
         while (!is_bool($this->get_channel_packet($client_channel))) {
         }
 
-        if ($this->is_timeout) {
-            $this->disconnect();
-        }
-
         if ($want_reply) {
             $this->send_binary_packet(pack('CN', MessageType::CHANNEL_CLOSE, $this->server_channels[$client_channel]));
         }
 
+        $this->close_channel_bitmap($client_channel);
+    }
+
+    /**
+     * Maintains execution state bitmap in response to channel closure
+     */
+    private function close_channel_bitmap(int $client_channel): void
+    {
+        switch ($client_channel) {
+            case self::CHANNEL_SHELL:
+                // Shell status has been maintained in the bitmap for backwards
+                //  compatibility sake, but can be removed going forward
                 if ($this->bitmap & self::MASK_SHELL) {
                     $this->bitmap &= ~self::MASK_SHELL;
                 }
+                break;
+        }
     }
 
     /**

tests/Functional/Net/SSH2Test.php

@@ -15,9 +15,28 @@ use phpseclib3\Tests\PhpseclibFunctionalTestCase;
 
 class SSH2Test extends PhpseclibFunctionalTestCase
 {
+    public function getSSH2(): SSH2
+    {
+        return new SSH2($this->getEnv('SSH_HOSTNAME'), 22);
+    }
+
+    public function getSSH2Login(): SSH2
+    {
+        $ssh = $this->getSSH2();
+
+        $username = $this->getEnv('SSH_USERNAME');
+        $password = $this->getEnv('SSH_PASSWORD');
+        $this->assertTrue(
+            $ssh->login($username, $password),
+            'SSH2 login using password failed.'
+        );
+
+        return $ssh;
+    }
+
     public function testConstructor(): SSH2
     {
-        $ssh = new SSH2($this->getEnv('SSH_HOSTNAME'));
+        $ssh = $this->getSSH2();
 
         $this->assertIsObject(
             $ssh,
@@ -44,6 +63,17 @@ class SSH2Test extends PhpseclibFunctionalTestCase
             'Failed asserting that SSH2 is not authenticated after construction.'
         );
 
+        $this->assertFalse(
+            $ssh->isShellOpen(),
+            'Failed asserting that SSH2 does not have open shell after construction.'
+        );
+
+        $this->assertEquals(
+            0,
+            $ssh->getInteractiveChannelId(),
+            'Failed asserting that channel identifier 0 is returned.'
+        );
+
         $this->assertNotEmpty(
             $ssh->getServerPublicHostKey(),
             'Failed asserting that a non-empty public host key was fetched.'
@@ -84,6 +114,11 @@ class SSH2Test extends PhpseclibFunctionalTestCase
             'Failed asserting that SSH2 is not authenticated after bad login attempt.'
         );
 
+        $this->assertFalse(
+            $ssh->isShellOpen(),
+            'Failed asserting that SSH2 does not have open shell after bad login attempt.'
+        );
+
         return $ssh;
     }
 
@@ -104,6 +139,11 @@ class SSH2Test extends PhpseclibFunctionalTestCase
             'Failed asserting that SSH2 is authenticated after good login attempt.'
         );
 
+        $this->assertFalse(
+            $ssh->isShellOpen(),
+            'Failed asserting that SSH2 does not have open shell after good login attempt.'
+        );
+
         return $ssh;
     }
 
@@ -123,12 +163,28 @@ class SSH2Test extends PhpseclibFunctionalTestCase
             ->will($this->returnValue(true));
         $ssh->exec('pwd', [$callbackObject, 'callbackMethod']);
 
+        $this->assertFalse(
+            $ssh->isPTYOpen(),
+            'Failed asserting that SSH2 does not have open exec channel after exec.'
+        );
+
+        $this->assertFalse(
+            $ssh->isShellOpen(),
+            'Failed asserting that SSH2 does not have open shell channel after exec.'
+        );
+
+        $this->assertEquals(
+            0,
+            $ssh->getInteractiveChannelId(),
+            'Failed asserting that channel identifier 0 is returned after exec.'
+        );
+
         return $ssh;
     }
 
     public function testGetServerPublicHostKey(): void
     {
-        $ssh = new SSH2($this->getEnv('SSH_HOSTNAME'));
+        $ssh = $this->getSSH2();
 
         $this->assertIsString($ssh->getServerPublicHostKey());
     }
@@ -153,11 +209,65 @@ class SSH2Test extends PhpseclibFunctionalTestCase
     public function testDisablePTY(SSH2 $ssh): SSH2
     {
         $ssh->enablePTY();
+
+        $this->assertTrue(
+            $ssh->isPTYEnabled(),
+            'Failed asserting that pty was enabled.'
+        );
+
+        $this->assertFalse(
+            $ssh->isPTYOpen(),
+            'Failed asserting that pty was not open after enable.'
+        );
+
+        $this->assertEquals(
+            0,
+            $ssh->getInteractiveChannelId(),
+            'Failed asserting that 0 channel identifier is returned prior to opening.'
+        );
+
         $ssh->exec('ls -latr');
+
+        $this->assertTrue(
+            $ssh->isPTYOpen(),
+            'Failed asserting that pty was open.'
+        );
+
+        $this->assertFalse(
+            $ssh->isShellOpen(),
+            'Failed asserting that shell was not open after pty exec.'
+        );
+
+        $this->assertEquals(
+            SSH2::CHANNEL_EXEC,
+            $ssh->getInteractiveChannelId(),
+            'Failed asserting that exec channel identifier is returned after exec.'
+        );
+
         $ssh->disablePTY();
+
+        $this->assertFalse(
+            $ssh->isPTYEnabled(),
+            'Failed asserting that pty was disabled.'
+        );
+
+        $this->assertFalse(
+            $ssh->isPTYOpen(),
+            'Failed asserting that pty was not open after disable.'
+        );
+
+        $this->assertEquals(
+            SSH2::CHANNEL_EXEC,
+            $ssh->getInteractiveChannelId(),
+            'Failed asserting that exec channel identifier is returned after pty exec close.'
+        );
+
         $ssh->exec('pwd');
 
-        $this->assertTrue(true);
+        $this->assertFalse(
+            $ssh->isPTYOpen(),
+            'Failed asserting that pty was not open after exec.'
+        );
 
         return $ssh;
     }
@@ -184,13 +294,248 @@ class SSH2Test extends PhpseclibFunctionalTestCase
 
         $ssh->write("ping 127.0.0.1\n");
 
+        $this->assertTrue(
+            $ssh->isShellOpen(),
+            'Failed asserting that SSH2 has open shell after shell read/write.'
+        );
+
+        $this->assertFalse(
+            $ssh->isPTYOpen(),
+            'Failed asserting that pty was not open after shell read/write.'
+        );
+
+        $this->assertEquals(
+            SSH2::CHANNEL_SHELL,
+            $ssh->getInteractiveChannelId(),
+            'Failed asserting that shell channel identifier is returned after shell read/write.'
+        );
+
         $ssh->enablePTY();
-        $ssh->exec('bash');
+
+        $this->assertTrue(
+            $ssh->exec('bash'),
+            'Failed asserting exec command succeeded.'
+        );
+
+        $this->assertTrue(
+            $ssh->isShellOpen(),
+            'Failed asserting that SSH2 has open shell after pty exec.'
+        );
+
+        $this->assertTrue(
+            $ssh->isPTYOpen(),
+            'Failed asserting that pty was not open after exec.'
+        );
+
+        $this->assertEquals(
+            SSH2::CHANNEL_EXEC,
+            $ssh->getInteractiveChannelId(),
+            'Failed asserting that exec channel identifier is returned after pty exec.'
+        );
 
         $ssh->write("ls -latr\n");
 
         $ssh->setTimeout(1);
 
         $this->assertIsString($ssh->read());
+
+        $this->assertTrue(
+            $ssh->isTimeout(),
+            'Failed asserting that pty exec read timed out'
+        );
+
+        $this->assertTrue(
+            $ssh->isShellOpen(),
+            'Failed asserting that SSH2 shell remains open across pty exec read/write.'
+        );
+
+        $this->assertTrue(
+            $ssh->isPTYOpen(),
+            'Failed asserting that pty was open after read timeout.'
+        );
+    }
+
+    public function testOpenShell(): SSH2
+    {
+        $ssh = $this->getSSH2Login();
+
+        $this->assertTrue(
+            $ssh->openShell(),
+            'SSH2 shell initialization failed.'
+        );
+
+        $this->assertTrue(
+            $ssh->isShellOpen(),
+            'Failed asserting that SSH2 has open shell after init.'
+        );
+
+        $this->assertNotFalse(
+            $ssh->read(),
+            'Failed asserting that read succeeds.'
+        );
+
+        $ssh->write('hello');
+
+        $this->assertTrue(
+            $ssh->isShellOpen(),
+            'Failed asserting that SSH2 has open shell after read/write.'
+        );
+
+        $this->assertEquals(
+            SSH2::CHANNEL_SHELL,
+            $ssh->getInteractiveChannelId(),
+            'Failed asserting that shell channel identifier is returned after read/write.'
+        );
+
+        return $ssh;
+    }
+
+    /**
+     * @depends testOpenShell
+     */
+    public function testResetOpenShell(SSH2 $ssh): void
+    {
+        $ssh->reset();
+
+        $this->assertFalse(
+            $ssh->isShellOpen(),
+            'Failed asserting that SSH2 has open shell after reset.'
+        );
+
+        $this->assertEquals(
+            SSH2::CHANNEL_SHELL,
+            $ssh->getInteractiveChannelId(),
+            'Failed asserting that shell channel identifier is returned after reset.'
+        );
+    }
+
+    public function testMultipleExecPty(): void
+    {
+        $this->expectException(\RuntimeException::class);
+        $this->expectExceptionMessage('If you want to run multiple exec()\'s you will need to disable (and re-enable if appropriate) a PTY for each one.');
+
+        $ssh = $this->getSSH2Login();
+
+        $ssh->enablePTY();
+
+        $ssh->exec('bash');
+
+        $ssh->exec('bash');
+    }
+
+    public function testMultipleInteractiveChannels(): void
+    {
+        $ssh = $this->getSSH2Login();
+
+        $this->assertTrue(
+            $ssh->openShell(),
+            'SSH2 shell initialization failed.'
+        );
+
+        $this->assertEquals(
+            SSH2::CHANNEL_SHELL,
+            $ssh->getInteractiveChannelId(),
+            'Failed asserting that shell channel identifier is returned after open shell.'
+        );
+
+        $ssh->setTimeout(1);
+
+        $this->assertIsString(
+            $ssh->read(),
+            'Failed asserting that read succeeds after shell init'
+        );
+
+        $directory = $ssh->exec('pwd');
+
+        $this->assertFalse(
+            $ssh->isTimeout(),
+            'failed'
+        );
+
+        $this->assertIsString(
+            $directory,
+            'Failed asserting that exec succeeds after shell read/write'
+        );
+
+        $ssh->write("pwd\n");
+
+        $this->assertStringContainsString(
+            trim($directory),
+            $ssh->read(),
+            'Failed asserting that current directory can be read from shell after exec'
+        );
+
+        $ssh->enablePTY();
+
+        $this->assertTrue(
+            $ssh->exec('bash'),
+            'Failed asserting that pty exec succeeds'
+        );
+
+        $this->assertTrue(
+            $ssh->isShellOpen(),
+            'Failed asserting that SSH2 has open shell after pty exec.'
+        );
+
+        $this->assertEquals(
+            SSH2::CHANNEL_EXEC,
+            $ssh->getInteractiveChannelId(),
+            'Failed asserting that exec channel identifier is returned after pty exec.'
+        );
+
+        $ssh->write("pwd\n", SSH2::CHANNEL_SHELL);
+
+        $this->assertStringContainsString(
+            trim($directory),
+            $ssh->read('', SSH2::READ_SIMPLE, SSH2::CHANNEL_SHELL),
+            'Failed asserting that current directory can be read from shell after pty exec'
+        );
+
+        $this->assertTrue(
+            $ssh->isPTYOpen(),
+            'Failed asserting that SSH2 has open pty exec after shell read/write.'
+        );
+
+        $ssh->write("pwd\n", SSH2::CHANNEL_EXEC);
+
+        $this->assertIsString(
+            $ssh->read('', SSH2::READ_SIMPLE, SSH2::CHANNEL_EXEC),
+            'Failed asserting that pty exec read succeeds'
+        );
+
+        $ssh->reset(SSH2::CHANNEL_EXEC);
+
+        $this->assertFalse(
+            $ssh->isPTYOpen(),
+            'Failed asserting that SSH2 has closed pty exec after reset.'
+        );
+
+        $ssh->disablePTY();
+
+        $this->assertTrue(
+            $ssh->isShellOpen(),
+            'Failed asserting that SSH2 has open shell after pty exec.'
+        );
+
+        $ssh->write("pwd\n", SSH2::CHANNEL_SHELL);
+
+        $this->assertStringContainsString(
+            trim($directory),
+            $ssh->read('', SSH2::READ_SIMPLE, SSH2::CHANNEL_SHELL),
+            'Failed asserting that current directory can be read from shell after pty exec'
+        );
+
+        $ssh->reset(SSH2::CHANNEL_SHELL);
+
+        $this->assertFalse(
+            $ssh->isShellOpen(),
+            'Failed asserting that SSH2 has closed shell after reset.'
+        );
+
+        $this->assertEquals(
+            SSH2::CHANNEL_EXEC,
+            $ssh->getInteractiveChannelId(),
+            'Failed asserting that exec channel identifier is maintained as last opened channel.'
+        );
     }
 }

tests/Unit/Net/SSH2UnitTest.php

@@ -10,6 +10,7 @@ declare(strict_types=1);
 
 namespace phpseclib3\Tests\Unit\Net;
 
+use phpseclib3\Exception\InsufficientSetupException;
 use phpseclib3\Net\SSH2;
 use phpseclib3\Tests\PhpseclibTestCase;
 
@@ -143,6 +144,71 @@ class SSH2UnitTest extends PhpseclibTestCase
         $this->assertSame('{' . spl_object_hash($ssh) . '}', $ssh->getResourceId());
     }
 
+    /**
+     * @requires PHPUnit < 10
+     */
+    public function testReadUnauthenticated(): void
+    {
+        $this->expectException(InsufficientSetupException::class);
+        $this->expectExceptionMessage('Operation disallowed prior to login()');
+
+        $ssh = $this->createSSHMock();
+
+        $ssh->read();
+    }
+
+    /**
+     * @requires PHPUnit < 10
+     */
+    public function testWriteUnauthenticated(): void
+    {
+        $this->expectException(InsufficientSetupException::class);
+        $this->expectExceptionMessage('Operation disallowed prior to login()');
+
+        $ssh = $this->createSSHMock();
+
+        $ssh->write('');
+    }
+
+    /**
+     * @requires PHPUnit < 10
+     */
+    public function testWriteOpensShell(): void
+    {
+        $ssh = $this->getMockBuilder(SSH2::class)
+            ->disableOriginalConstructor()
+            ->setMethods(['__destruct', 'isAuthenticated', 'openShell', 'send_channel_packet'])
+            ->getMock();
+        $ssh->expects($this->once())
+            ->method('isAuthenticated')
+            ->willReturn(true);
+        $ssh->expects($this->once())
+            ->method('openShell')
+            ->willReturn(true);
+        $ssh->expects($this->once())
+            ->method('send_channel_packet')
+            ->with(SSH2::CHANNEL_SHELL, 'hello');
+
+        $ssh->write('hello');
+    }
+
+    /**
+     * @requires PHPUnit < 10
+     */
+    public function testOpenShellWhenOpen(): void
+    {
+        $ssh = $this->getMockBuilder(SSH2::class)
+            ->disableOriginalConstructor()
+            ->setMethods(['__destruct', 'isShellOpen'])
+            ->getMock();
+
+        $ssh->expects($this->once())
+            ->method('isShellOpen')
+            ->willReturn(true);
+
+        $this->assertFalse($ssh->openShell());
+    }
+
     public function testGetTimeout(): void
     {
         $ssh = new SSH2('localhost');