--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/app/src/main/java/ch/ethz/ssh2/Session.java	Thu Dec 03 11:23:55 2015 -0800
@@ -0,0 +1,476 @@
+/*
+ * Copyright (c) 2006-2011 Christian Plattner. All rights reserved.
+ * Please refer to the LICENSE.txt for licensing details.
+ */
+package ch.ethz.ssh2;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.security.SecureRandom;
+
+import ch.ethz.ssh2.channel.Channel;
+import ch.ethz.ssh2.channel.ChannelManager;
+import ch.ethz.ssh2.channel.X11ServerData;
+
+/**
+ * A <code>Session</code> is a remote execution of a program. "Program" means
+ * in this context either a shell, an application or a system command. The
+ * program may or may not have a tty. Only one single program can be started on
+ * a session. However, multiple sessions can be active simultaneously.
+ *
+ * @author Christian Plattner
+ * @version $Id: Session.java 96 2014-04-08 15:14:37Z dkocher@sudo.ch $
+ */
+public class Session {
+    private ChannelManager cm;
+    private Channel cn;
+
+    private boolean flag_pty_requested = false;
+    private boolean flag_x11_requested = false;
+    private boolean flag_execution_started = false;
+    private boolean flag_closed = false;
+
+    private String x11FakeCookie = null;
+
+    private final SecureRandom rnd;
+
+    protected Session(ChannelManager cm, SecureRandom rnd) throws IOException {
+        this.cm = cm;
+        this.cn = cm.openSessionChannel();
+        this.rnd = rnd;
+    }
+
+    /**
+     * Basically just a wrapper for lazy people - identical to calling
+     * <code>requestPTY("dumb", 0, 0, 0, 0, null)</code>.
+     *
+     * @throws IOException
+     */
+    public void requestDumbPTY() throws IOException {
+        requestPTY("dumb", 0, 0, 0, 0, null);
+    }
+
+    /**
+     * Basically just another wrapper for lazy people - identical to calling
+     * <code>requestPTY(term, 0, 0, 0, 0, null)</code>.
+     *
+     * @throws IOException
+     */
+    public void requestPTY(String term) throws IOException {
+        requestPTY(term, 0, 0, 0, 0, null);
+    }
+
+    /**
+     * Allocate a pseudo-terminal for this session.
+     * <p/>
+     * This method may only be called before a program or shell is started in
+     * this session.
+     * <p/>
+     * Different aspects can be specified:
+     * <p/>
+     * <ul>
+     * <li>The TERM environment variable value (e.g., vt100)</li>
+     * <li>The terminal's dimensions.</li>
+     * <li>The encoded terminal modes.</li>
+     * </ul>
+     * Zero dimension parameters are ignored. The character/row dimensions
+     * override the pixel dimensions (when nonzero). Pixel dimensions refer to
+     * the drawable area of the window. The dimension parameters are only
+     * informational. The encoding of terminal modes (parameter
+     * <code>terminal_modes</code>) is described in RFC4254.
+     *
+     * @param term The TERM environment variable value (e.g., vt100)
+     * @param term_width_characters terminal width, characters (e.g., 80)
+     * @param term_height_characters terminal height, rows (e.g., 24)
+     * @param term_width_pixels terminal width, pixels (e.g., 640)
+     * @param term_height_pixels terminal height, pixels (e.g., 480)
+     * @param terminal_modes encoded terminal modes (may be <code>null</code>)
+     * @throws IOException
+     */
+    public void requestPTY(String term, int term_width_characters, int term_height_characters, int term_width_pixels,
+                           int term_height_pixels, byte[] terminal_modes) throws IOException {
+        if (term == null)
+            throw new IllegalArgumentException("TERM cannot be null.");
+
+        if ((terminal_modes != null) && (terminal_modes.length > 0)) {
+            if (terminal_modes[terminal_modes.length - 1] != 0)
+                throw new IOException("Illegal terminal modes description, does not end in zero byte");
+        }
+        else
+            terminal_modes = new byte[] {0};
+
+        synchronized (this) {
+            /* The following is just a nicer error, we would catch it anyway later in the channel code */
+            if (flag_closed)
+                throw new IOException("This session is closed.");
+
+            if (flag_pty_requested)
+                throw new IOException("A PTY was already requested.");
+
+            if (flag_execution_started)
+                throw new IOException(
+                    "Cannot request PTY at this stage anymore, a remote execution has already started.");
+
+            flag_pty_requested = true;
+        }
+
+        cm.requestPTY(cn, term, term_width_characters, term_height_characters, term_width_pixels, term_height_pixels,
+                      terminal_modes);
+    }
+
+    /**
+     * Tells the server that the size of the terminal has changed.
+     *
+     * See {@link #requestPTY(String, int, int, int, int, byte[])} for more details about how parameters are interpreted.
+     *
+     * @param term_width_characters
+     *            terminal width, characters (e.g., 80)
+     * @param term_height_characters
+     *            terminal height, rows (e.g., 24)
+     * @param term_width_pixels
+     *            terminal width, pixels (e.g., 640)
+     * @param term_height_pixels
+     *            terminal height, pixels (e.g., 480)
+     * @throws IOException
+     */
+    public void resizePTY(int term_width_characters, int term_height_characters, int term_width_pixels, int term_height_pixels) throws IOException {
+        requestWindowChange(term_width_characters, term_height_characters, term_width_pixels, term_height_pixels);
+    }
+
+    public void requestWindowChange(int term_width_characters, int term_height_characters, int term_width_pixels,
+                                    int term_height_pixels) throws IOException {
+        synchronized (this) {
+            /* The following is just a nicer error, we would catch it anyway later in the channel code */
+            if (flag_closed)
+                throw new IOException("This session is closed.");
+
+            if (!flag_pty_requested)
+                throw new IOException("A PTY was not requested.");
+        }
+
+        cm.requestWindowChange(cn, term_width_characters, term_height_characters, term_width_pixels, term_height_pixels);
+    }
+
+    /**
+     * Request X11 forwarding for the current session.
+     * <p/>
+     * You have to supply the name and port of your X-server.
+     * <p/>
+     * This method may only be called before a program or shell is started in
+     * this session.
+     *
+     * @param hostname the hostname of the real (target) X11 server (e.g., 127.0.0.1)
+     * @param port the port of the real (target) X11 server (e.g., 6010)
+     * @param cookie if non-null, then present this cookie to the real X11 server
+     * @param singleConnection if true, then the server is instructed to only forward one single
+     * connection, no more connections shall be forwarded after first, or after the session
+     * channel has been closed
+     * @throws IOException
+     */
+    public void requestX11Forwarding(String hostname, int port, byte[] cookie, boolean singleConnection)
+    throws IOException {
+        if (hostname == null)
+            throw new IllegalArgumentException("hostname argument may not be null");
+
+        synchronized (this) {
+            /* The following is just a nicer error, we would catch it anyway later in the channel code */
+            if (flag_closed)
+                throw new IOException("This session is closed.");
+
+            if (flag_x11_requested)
+                throw new IOException("X11 forwarding was already requested.");
+
+            if (flag_execution_started)
+                throw new IOException(
+                    "Cannot request X11 forwarding at this stage anymore, a remote execution has already started.");
+
+            flag_x11_requested = true;
+        }
+
+        /* X11ServerData - used to store data about the target X11 server */
+        X11ServerData x11data = new X11ServerData();
+        x11data.hostname = hostname;
+        x11data.port = port;
+        x11data.x11_magic_cookie = cookie; /* if non-null, then present this cookie to the real X11 server */
+        /* Generate fake cookie - this one is used between remote clients and the ganymed proxy */
+        byte[] fakeCookie = new byte[16];
+        String hexEncodedFakeCookie;
+
+        /* Make sure that this fake cookie is unique for this connection */
+
+        while (true) {
+            rnd.nextBytes(fakeCookie);
+            /* Generate also hex representation of fake cookie */
+            StringBuilder tmp = new StringBuilder(32);
+
+            for (int i = 0; i < fakeCookie.length; i++) {
+                String digit2 = Integer.toHexString(fakeCookie[i] & 0xff);
+                tmp.append((digit2.length() == 2) ? digit2 : "0" + digit2);
+            }
+
+            hexEncodedFakeCookie = tmp.toString();
+
+            /* Well, yes, chances are low, but we want to be on the safe side */
+
+            if (cm.checkX11Cookie(hexEncodedFakeCookie) == null)
+                break;
+        }
+
+        /* Ask for X11 forwarding */
+        cm.requestX11(cn, singleConnection, "MIT-MAGIC-COOKIE-1", hexEncodedFakeCookie, 0);
+
+        /* OK, that went fine, get ready to accept X11 connections... */
+        /* ... but only if the user has not called close() in the meantime =) */
+
+        synchronized (this) {
+            if (flag_closed == false) {
+                this.x11FakeCookie = hexEncodedFakeCookie;
+                cm.registerX11Cookie(hexEncodedFakeCookie, x11data);
+            }
+        }
+
+        /* Now it is safe to start remote X11 programs */
+    }
+
+    /**
+     * Execute a command on the remote machine.
+     *
+     * @param cmd The command to execute on the remote host.
+     * @throws IOException
+     */
+    public void execCommand(String cmd) throws IOException {
+        this.execCommand(cmd, null);
+    }
+
+    /**
+     * Execute a command on the remote machine.
+     *
+     * @param cmd The command to execute on the remote host.
+     * @param charsetName The charset used to convert between Java Unicode Strings and byte encodings
+     * @throws IOException
+     */
+    public void execCommand(String cmd, String charsetName) throws IOException {
+        if (cmd == null)
+            throw new IllegalArgumentException("cmd argument may not be null");
+
+        synchronized (this) {
+            /* The following is just a nicer error, we would catch it anyway later in the channel code */
+            if (flag_closed)
+                throw new IOException("This session is closed.");
+
+            if (flag_execution_started)
+                throw new IOException("A remote execution has already started.");
+
+            flag_execution_started = true;
+        }
+
+        cm.requestExecCommand(cn, cmd, charsetName);
+    }
+
+    /**
+     * Start a shell on the remote machine.
+     *
+     * @throws IOException
+     */
+    public void startShell() throws IOException {
+        synchronized (this) {
+            /* The following is just a nicer error, we would catch it anyway later in the channel code */
+            if (flag_closed)
+                throw new IOException("This session is closed.");
+
+            if (flag_execution_started)
+                throw new IOException("A remote execution has already started.");
+
+            flag_execution_started = true;
+        }
+
+        cm.requestShell(cn);
+    }
+
+    /**
+     * Start a subsystem on the remote machine.
+     * Unless you know what you are doing, you will never need this.
+     *
+     * @param name the name of the subsystem.
+     * @throws IOException
+     */
+    public void startSubSystem(String name) throws IOException {
+        if (name == null)
+            throw new IllegalArgumentException("name argument may not be null");
+
+        synchronized (this) {
+            /* The following is just a nicer error, we would catch it anyway later in the channel code */
+            if (flag_closed)
+                throw new IOException("This session is closed.");
+
+            if (flag_execution_started)
+                throw new IOException("A remote execution has already started.");
+
+            flag_execution_started = true;
+        }
+
+        cm.requestSubSystem(cn, name);
+    }
+
+    /**
+     * Request authentication agent forwarding.
+     * @param agent object that implements the callbacks
+     *
+     * @throws IOException in case of any problem or when the session is closed
+     */
+
+    public synchronized void requestAuthAgentForwarding(AuthAgentCallback agent) throws IOException {
+        synchronized (this) {
+            /*
+             * The following is just a nicer error, we would catch it anyway
+             * later in the channel code
+             */
+            if (flag_closed)
+                throw new IOException("This session is closed.");
+        }
+
+        cm.requestChannelAgentForwarding(cn, agent);
+    }
+
+    public int getState() {
+        return cn.getState();
+    }
+
+    public InputStream getStdout() {
+        return cn.getStdoutStream();
+    }
+
+    public InputStream getStderr() {
+        return cn.getStderrStream();
+    }
+
+    public OutputStream getStdin() {
+        return cn.getStdinStream();
+    }
+
+    /**
+     * This method blocks until there is more data available on either the
+     * stdout or stderr InputStream of this <code>Session</code>. Very useful
+     * if you do not want to use two parallel threads for reading from the two
+     * InputStreams. One can also specify a timeout. NOTE: do NOT call this
+     * method if you use concurrent threads that operate on either of the two
+     * InputStreams of this <code>Session</code> (otherwise this method may
+     * block, even though more data is available).
+     *
+     * @param timeout The (non-negative) timeout in <code>ms</code>. <code>0</code> means no
+     * timeout, the call may block forever.
+     * @return <ul>
+     *         <li><code>0</code> if no more data will arrive.</li>
+     *         <li><code>1</code> if more data is available.</li>
+     *         <li><code>-1</code> if a timeout occurred.</li>
+     *         </ul>
+     * @throws IOException
+     * @deprecated This method has been replaced with a much more powerful wait-for-condition
+     *             interface and therefore acts only as a wrapper.
+     */
+    public int waitUntilDataAvailable(long timeout) throws IOException {
+        if (timeout < 0)
+            throw new IllegalArgumentException("timeout must not be negative!");
+
+        int conditions = cm.waitForCondition(cn, timeout, ChannelCondition.STDOUT_DATA | ChannelCondition.STDERR_DATA
+                                             | ChannelCondition.EOF);
+
+        if ((conditions & ChannelCondition.TIMEOUT) != 0)
+            return -1;
+
+        if ((conditions & (ChannelCondition.STDOUT_DATA | ChannelCondition.STDERR_DATA)) != 0)
+            return 1;
+
+        /* Here we do not need to check separately for CLOSED, since CLOSED implies EOF */
+
+        if ((conditions & ChannelCondition.EOF) != 0)
+            return 0;
+
+        throw new IllegalStateException("Unexpected condition result (" + conditions + ")");
+    }
+
+    /**
+     * This method blocks until certain conditions hold true on the underlying SSH-2 channel.
+     * <p/>
+     * This method returns as soon as one of the following happens:
+     * <ul>
+     * <li>at least of the specified conditions (see {@link ChannelCondition}) holds true</li>
+     * <li>timeout > 0 and a timeout occured (TIMEOUT will be set in result conditions)</a>
+     * <li>the underlying channel was closed (CLOSED will be set in result conditions)</a>
+     * </ul>
+     * <p/>
+     * In any case, the result value contains ALL current conditions, which may be more
+     * than the specified condition set (i.e., never use the "==" operator to test for conditions
+     * in the bitmask, see also comments in {@link ChannelCondition}).
+     * <p/>
+     * Note: do NOT call this method if you want to wait for STDOUT_DATA or STDERR_DATA and
+     * there are concurrent threads (e.g., StreamGobblers) that operate on either of the two
+     * InputStreams of this <code>Session</code> (otherwise this method may
+     * block, even though more data is available in the StreamGobblers).
+     *
+     * @param condition_set a bitmask based on {@link ChannelCondition} values
+     * @param timeout non-negative timeout in ms, <code>0</code> means no timeout
+     * @return all bitmask specifying all current conditions that are true
+     */
+
+    public int waitForCondition(int condition_set, long timeout) throws IOException {
+        if (timeout < 0)
+            throw new IllegalArgumentException("timeout must be non-negative!");
+
+        return cm.waitForCondition(cn, timeout, condition_set);
+    }
+
+    /**
+     * Get the exit code/status from the remote command - if available. Be
+     * careful - not all server implementations return this value. It is
+     * generally a good idea to call this method only when all data from the
+     * remote side has been consumed (see also the <code<WaitForCondition</code> method).
+     *
+     * @return An <code>Integer</code> holding the exit code, or
+     *         <code>null</code> if no exit code is (yet) available.
+     */
+    public Integer getExitStatus() {
+        return cn.getExitStatus();
+    }
+
+    /**
+     * Get the name of the signal by which the process on the remote side was
+     * stopped - if available and applicable. Be careful - not all server
+     * implementations return this value.
+     *
+     * @return An <code>String</code> holding the name of the signal, or
+     *         <code>null</code> if the process exited normally or is still
+     *         running (or if the server forgot to send this information).
+     */
+    public String getExitSignal() {
+        return cn.getExitSignal();
+    }
+
+    /**
+     * Close this session. NEVER forget to call this method to free up resources -
+     * even if you got an exception from one of the other methods (or when
+     * getting an Exception on the Input- or OutputStreams). Sometimes these other
+     * methods may throw an exception, saying that the underlying channel is
+     * closed (this can happen, e.g., if the other server sent a close message.)
+     * However, as long as you have not called the <code>close()</code>
+     * method, you may be wasting (local) resources.
+     */
+    public void close() {
+        synchronized (this) {
+            if (flag_closed)
+                return;
+
+            flag_closed = true;
+
+            if (x11FakeCookie != null)
+                cm.unRegisterX11Cookie(x11FakeCookie, true);
+
+            try {
+                cm.closeChannel(cn, "Closed due to user request", true);
+            }
+            catch (IOException ignored) {
+            }
+        }
+    }
+}