line source
+ −
+ − package com.trilead.ssh2;
+ −
+ − import java.io.IOException;
+ − import java.io.InputStream;
+ − import java.io.OutputStream;
+ − import java.security.SecureRandom;
+ −
+ − import com.trilead.ssh2.channel.Channel;
+ − import com.trilead.ssh2.channel.ChannelManager;
+ − import com.trilead.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, plattner@trilead.com
+ − * @version $Id: Session.java,v 1.2 2008/03/03 07:01:36 cplattne Exp $
+ − */
+ − public class Session {
+ − ChannelManager cm;
+ − Channel cn;
+ −
+ − boolean flag_pty_requested = false;
+ − boolean flag_x11_requested = false;
+ − boolean flag_execution_started = false;
+ − boolean flag_closed = false;
+ −
+ − String x11FakeCookie = null;
+ −
+ − final SecureRandom rnd;
+ −
+ − 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);
+ − }
+ −
+ − /**
+ − * Inform other side of connection that our PTY has resized.
+ − * <p>
+ − * 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.
+ − *
+ − * @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 {
+ − 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.resizePTY(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 our 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 */
+ − StringBuffer tmp = new StringBuffer(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 {
+ − 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);
+ − }
+ −
+ − /**
+ − * 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);
+ − }
+ −
+ − /**
+ − * This method can be used to perform end-to-end session (i.e., SSH channel)
+ − * testing. It sends a 'ping' message to the server and waits for the 'pong'
+ − * from the server.
+ − * <p>
+ − * Implementation details: this method sends a SSH_MSG_CHANNEL_REQUEST request
+ − * ('trilead-ping') to the server and waits for the SSH_MSG_CHANNEL_FAILURE reply
+ − * packet.
+ − *
+ − * @throws IOException in case of any problem or when the session is closed
+ − */
+ − public void ping() 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.requestChannelTrileadPing(cn);
+ − }
+ −
+ − /**
+ − * 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 boolean 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.");
+ − }
+ −
+ − return cm.requestChannelAgentForwarding(cn, agent);
+ − }
+ −
+ − 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) {
+ − 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) {
+ − }
+ − }
+ − }
+ − }