Android™

Get Received SSH Bytes into a BinData

Demonstrates the Chilkat Ssh.GetReceivedBd method, which appends the bytes currently in a channel's normal receive buffer to a BinData. The first argument is the channel number and the second is the BinData. The channel receive buffer is cleared afterward; existing bytes in the BinData are preserved.

Background: When the remote command emits binary — a tarball, an image, a compressed stream — decoding it as text through a charset would corrupt it. BinData keeps the bytes exactly as received, so you can write them to a file, hash them, or hand them to another API. Like the StringBuilder form it appends, making it easy to accumulate across successive reads. On failure the BinData is left unchanged.

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// Important: Don't forget to include the call to System.loadLibrary
// as shown at the bottom of this code sample.
package com.test;

import android.app.Activity;
import com.chilkatsoft.*;

import android.widget.TextView;
import android.os.Bundle;

public class SimpleActivity extends Activity {

  private static final String TAG = "Chilkat";

  // Called when the activity is first created.
  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    boolean success = false;

    //  Demonstrates the Ssh.GetReceivedBd method, which appends the bytes currently in a channel's
    //  receive buffer to a BinData.  The 1st argument is the channel number and the 2nd is the
    //  BinData.  The channel receive buffer is cleared afterward.

    CkSsh ssh = new CkSsh();

    int sshPort = 22;
    success = ssh.Connect("ssh.example.com",sshPort);
    if (success == false) {
        Log.i(TAG, ssh.lastErrorText());
        return;
        }

    //  Normally you would not hard-code the password in source.  You should instead obtain it
    //  from an interactive prompt, environment variable, or a secrets vault.
    String password = "mySshPassword";

    success = ssh.AuthenticatePw("mySshLogin",password);
    if (success == false) {
        Log.i(TAG, ssh.lastErrorText());
        return;
        }

    int channelNum = ssh.OpenSessionChannel();
    if (channelNum < 0) {
        Log.i(TAG, ssh.lastErrorText());
        return;
        }

    //  Run a command whose output may be binary.
    success = ssh.SendReqExec(channelNum,"cat /usr/bin/hostname");
    if (success == false) {
        Log.i(TAG, ssh.lastErrorText());
        return;
        }

    //  IMPORTANT: Set a read timeout.  ReadTimeoutMs defaults to 0, which means no limit -- without
    //  it, this call waits forever if the server never sends channel close.
    ssh.put_ReadTimeoutMs(15000);

    success = ssh.ChannelReceiveToClose(channelNum);
    if (success == false) {
        Log.i(TAG, ssh.lastErrorText());
        return;
        }

    //  Append the raw received bytes to a BinData.  Existing bytes in the BinData are preserved.
    CkBinData bd = new CkBinData();
    success = ssh.GetReceivedBd(channelNum,bd);
    if (success == false) {
        Log.i(TAG, ssh.lastErrorText());
        return;
        }

    Log.i(TAG, "Bytes received: " + String.valueOf(bd.get_NumBytes()));

    ssh.Disconnect();

  }

  static {
      System.loadLibrary("chilkat");

      // Note: If the incorrect library name is passed to System.loadLibrary,
      // then you will see the following error message at application startup:
      //"The application <your-application-name> has stopped unexpectedly. Please try again."
  }
}