Java Code Examples for com.jcraft.jsch.ChannelExec#isClosed()

/**
 * Connect to a remote host via SSH and execute a command.
 * 
 * @param host
 *          Host to connect to
 * @param user
 *          User to login with
 * @param password
 *          Password for the user
 * @param command
 *          Command to execute
 * @return The result of the command execution
 */
private Result executeSshCommand(final String host, final String user,
    final String password, final String command) {
  
  StringBuilder result = new StringBuilder();
  
  try {
    JSch jsch = new JSch();
    Session session = jsch.getSession(user, host, 22);
    session.setUserInfo(createUserInfo(password));
    session.connect(5000);

    ChannelExec channel = (ChannelExec) session.openChannel("exec");
    channel.setCommand(command);
    channel.setInputStream(null);
    channel.setErrStream(System.err);
    InputStream in = channel.getInputStream();

    channel.connect();

    byte[] tmp = new byte[1024];
    while (true) {
      while (in.available() > 0) {
        int i = in.read(tmp, 0, 1024);
        if (i < 0)
          break;
        result.append(new String(tmp, 0, i));
      }
      if (channel.isClosed()) {
        break;
      }
    }
    channel.disconnect();
    session.disconnect();
  } catch (Exception jex) {
    return createResult(Result.Status.ERROR, jex.getMessage());
  }
 
  return createResult(Result.Status.OK, result.toString());
}
 

private String readChannelInputStream(ChannelExec channel) throws IOException
{
    try (InputStream in = channel.getInputStream();
            InputStreamReader reader = new InputStreamReader(in, StandardCharsets.UTF_8);
            StringWriter stringWriter = new StringWriter())
    {
        while (true)
        {
            IOUtils.copy(reader, stringWriter);
            if (channel.isClosed())
            {
                if (in.available() > 0)
                {
                    continue;
                }
                return stringWriter.toString();
            }
            Sleeper.sleep(Duration.ofSeconds(1));
        }
    }
}
 

/**
 * Wait for a given {@link ChannelExec} to be closed.
 * Will close channel if maxWait is set and exceeded.
 * @param channel the channel
 */
private void waitForChannelClosed(ChannelExec channel) {
    long startTime = System.currentTimeMillis();
    while (!channel.isClosed()) {
        // Check to see if we have been waiting too long, converts ms to minutes
        long elapsedTimeInMins =
                TimeUnit.MILLISECONDS.toMinutes(System.currentTimeMillis() - startTime);
        if (maxWait > 0 && elapsedTimeInMins > maxWait) {
            log.error("Task took too long to complete");
            channel.disconnect();
        }
        try {
            Thread.sleep(1000);
        }
        catch (InterruptedException e) {
            // Should not happen
        }
    }
}
 

/**
 * Reads std and error remote output which are then wrapped inside {@link RemoteCommandReturnInfo}
 *
 * @param channelExec the channel where the command is sent for execution
 * @param timeout the length of time in ms in which the method waits for a available byte(s) as a result of command
 * @return {@link RemoteCommandReturnInfo}
 */
private RemoteCommandReturnInfo getExecRemoteCommandReturnInfo(final ChannelExec channelExec, final long timeout)
        throws IOException, JSchException {

    final String output = scrubberService.scrub(readExecRemoteOutput(channelExec, timeout));
    LOGGER.debug("remote output = {}", output);

    String errorOutput = null;

    // wait for the channel to close before checking the exit status
    final long startTime = System.currentTimeMillis();
    while (!channelExec.isClosed()) {
        if ((System.currentTimeMillis() - startTime) > CHANNEL_EXEC_CLOSE_TIMEOUT) {
            errorOutput = MessageFormat.format("Wait for channel to close timeout! Timeout = {0} ms",
                    CHANNEL_EXEC_CLOSE_TIMEOUT);
            LOGGER.error(errorOutput);
            break;
        }
    }

    LOGGER.debug("Channel exec exit status = {}", channelExec.getExitStatus());

    if (channelExec.getExitStatus() != 0 && channelExec.getExitStatus() != -1) {
        errorOutput = readExecRemoteOutput(channelExec, timeout);
        LOGGER.debug("remote error output = {}", errorOutput);
    }

    return new RemoteCommandReturnInfo(channelExec.getExitStatus(), output, errorOutput);
}
 

/**
 * Connect to a remote host via SSH and execute a command.
 * 
 * @param host
 *          Host to connect to
 * @param user
 *          User to login with
 * @param password
 *          Password for the user
 * @param command
 *          Command to execute
 * @return The result of the command execution
 */
private Result executeSshCommand(final String host, final String user,
    final String password, final String command) {
  
  StringBuilder result = new StringBuilder();
  
  try {
    JSch jsch = new JSch();
    Session session = jsch.getSession(user, host, 22);
    session.setUserInfo(createUserInfo(password));
    session.connect(5000);

    ChannelExec channel = (ChannelExec) session.openChannel("exec");
    channel.setCommand(command);
    channel.setInputStream(null);
    channel.setErrStream(System.err);
    InputStream in = channel.getInputStream();

    channel.connect();

    byte[] tmp = new byte[1024];
    while (true) {
      while (in.available() > 0) {
        int i = in.read(tmp, 0, 1024);
        if (i < 0)
          break;
        result.append(new String(tmp, 0, i));
      }
      if (channel.isClosed()) {
        break;
      }
    }
    channel.disconnect();
    session.disconnect();
  } catch (Exception jex) {
    return createResult(Result.Status.ERROR, jex.getMessage());
  }
 
  return createResult(Result.Status.OK, result.toString());
}
 

/**
 * Executes a command and returns the (standard) output through a StringBuilder.
 *
 * @param command The command
 * @param output  The output
 * @return The exit code of the command
 * @throws JSchException       if a JSch error is detected.
 * @throws FileSystemException if a session cannot be created.
 * @throws IOException         if an I/O error is detected.
 */
private int executeCommand(final String command, final StringBuilder output) throws JSchException, IOException {
    final ChannelExec channel = (ChannelExec) getSession().openChannel("exec");
    try {
        channel.setCommand(command);
        channel.setInputStream(null);
        try (final InputStreamReader stream = new InputStreamReader(channel.getInputStream())) {
            channel.setErrStream(System.err, true);
            channel.connect(connectTimeoutMillis);

            // Read the stream
            final char[] buffer = new char[EXEC_BUFFER_SIZE];
            int read;
            while ((read = stream.read(buffer, 0, buffer.length)) >= 0) {
                output.append(buffer, 0, read);
            }
        }

        // Wait until the command finishes (should not be long since we read the output stream)
        while (!channel.isClosed()) {
            try {
                Thread.sleep(SLEEP_MILLIS);
            } catch (final Exception ee) {
                // TODO: swallow exception, really?
            }
        }
    } finally {
        channel.disconnect();
    }
    return channel.getExitStatus();
}
 

/**
 *
 * {@link  org.apache.commons.vfs2.provider.sftp.SftpFileSystem#executeCommand(java.lang.String, java.lang.StringBuilder) }
 */
private int executeCommand( String command, StringBuilder output ) throws JSchException, IOException {
  this.ensureSession();
  ChannelExec channel = (ChannelExec) this.session.openChannel( "exec" );
  channel.setCommand( command );
  channel.setInputStream( (InputStream) null );
  InputStreamReader stream = new InputStreamReader( channel.getInputStream() );
  channel.setErrStream( System.err, true );
  channel.connect();
  char[] buffer = new char[128];

  int read;
  while ( ( read = stream.read( buffer, 0, buffer.length ) ) >= 0 ) {
    output.append( buffer, 0, read );
  }

  stream.close();

  while ( !channel.isClosed() ) {
    try {
      Thread.sleep( 100L );
    } catch ( Exception exc ) {
      log.logMinimal( "Warning: Error session closing. " + exc.getMessage() );
    }
  }

  channel.disconnect();
  return channel.getExitStatus();
}
 

/**
 * Read the remote output for the exec channel. This is the code provided on the jcraft site with a timeout added.
 *
 * @param channelExec the exec channel
 * @param timeout     the maximum period of time for reading the channel output
 * @return the output from the channel
 * @throws IOException for any issues encoutered when retrieving the input stream from the channel
 */
private String readExecRemoteOutput(ChannelExec channelExec, long timeout) throws IOException {
    final BufferedInputStream bufIn = new BufferedInputStream(channelExec.getInputStream());
    final StringBuilder outputBuilder = new StringBuilder();

    final byte[] tmp = new byte[BYTE_CHUNK_SIZE];
    final long startTime = System.currentTimeMillis();
    final long readLoopSleepTime = Long.parseLong(ApplicationProperties.get(
            JSCH_EXEC_READ_REMOTE_OUTPUT_LOOP_SLEEP_TIME.getPropertyName(), READ_LOOP_SLEEP_TIME_DEFAULT_VALUE));

    while (true) {
        // read the stream
        while (bufIn.available() > 0) {
            int i = bufIn.read(tmp, 0, BYTE_CHUNK_SIZE);
            if (i < 0) {
                break;
            }
            outputBuilder.append(new String(tmp, 0, i, StandardCharsets.UTF_8));
        }

        // check if the channel is closed
        if (channelExec.isClosed()) {
            // check for any more bytes on the input stream
            sleep(readLoopSleepTime);

            if (bufIn.available() > 0) {
                continue;
            }

            LOGGER.debug("exit-status: {}", channelExec.getExitStatus());
            break;
        }

        // check timeout
        if ((System.currentTimeMillis() - startTime) > timeout) {
            LOGGER.warn("Remote exec output reading timeout!");
            break;
        }

        // If for some reason the channel is not getting closed, we should not hog CPU time with this loop hence
        // we sleep for a while
        sleep(readLoopSleepTime);
    }
    return outputBuilder.toString();
}
 

/**
 * Seems there are bad naming in the library the sysout is in
 * channel.getInputStream(); the syserr is in
 * ((ChannelExec)channel).setErrStream(os);
 *
 * @param channel
 *            the channel
 * @return the response on singe request
 */
public ResponseOnSingeRequest executeAndGenResponse(ChannelExec channel) {
    ResponseOnSingeRequest sshResponse = new ResponseOnSingeRequest();

    InputStream in = null;
    OutputStream outputStreamStdErr = new ByteArrayOutputStream();
    StringBuilder sbStdOut = new StringBuilder();
    try {

        in = channel.getInputStream();
        channel.setErrStream(outputStreamStdErr);

        byte[] tmp = new byte[ParallecGlobalConfig.sshBufferSize];
        while (true) {
            while (in.available() > 0) {
                int i = in.read(tmp, 0, ParallecGlobalConfig.sshBufferSize);
                if (i < 0)
                    break;
                sbStdOut.append(new String(tmp, 0, i));

            }

            if (channel.isClosed()) {
                if (in.available() > 0)
                    continue;
                sshResponse.setFailObtainResponse(false);

                // exit 0 is good
                int exitStatus = channel.getExitStatus();
                sshResponse.setStatusCodeInt(exitStatus);
                sshResponse.setStatusCode(Integer.toString(exitStatus));
                break;
            }

            Thread.sleep(ParallecGlobalConfig.sshSleepMIllisBtwReadBuffer);
        }

        sshResponse.setResponseBody(sbStdOut.toString());
        sshResponse.setErrorMessage(outputStreamStdErr.toString());
        sshResponse.setReceiveTimeNow();
    } catch (Exception t) {
        throw new RuntimeException(t);
    }

    return sshResponse;
}