Java

IMAP Use Existing SSH Tunnel

Demonstrates how to connect to an IMAP server using an existing SSH tunnel. This creates a new channel within the SSH tunnel, which can be a TCP or TLS connection, and is connected to a remote IMAP server through port forwarding. Java

import com.chilkatsoft.*;

public class ChilkatExample {

  static {
    try {
        System.loadLibrary("chilkat");
    } catch (UnsatisfiedLinkError e) {
      System.err.println("Native code library failed to load.\n" + e);
      System.exit(1);
    }
  }

  public static void main(String argv[])
  {
    boolean success = false;

    // This example assumes the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    CkSocket tunnel = new CkSocket();

    String sshHostname = "sftp.example.com";
    int sshPort = 22;

    // Connect to an SSH server and establish the SSH tunnel:
    success = tunnel.SshOpenTunnel(sshHostname,sshPort);
    if (success == false) {
        System.out.println(tunnel.lastErrorText());
        return;
        }

    // Authenticate with the SSH server via a login/password
    // or with a public key.  
    // This example demonstrates SSH password authentication.
    // Note: This is not authenticating with the IMAP server, it is
    // for authenticating with the SSH server, which is separate.
    success = tunnel.SshAuthenticatePw("mySshLogin","mySshPassword");
    if (success == false) {
        System.out.println(tunnel.lastErrorText());
        return;
        }

    // OK, the SSH tunnel is setup.  Now open a channel within the tunnel.
    // Once the channel is obtained, the Socket API may
    // be used exactly the same as usual, except all communications
    // are sent through the channel in the SSH tunnel.
    // Any number of channels may be created from the same SSH tunnel.
    // Multiple channels may coexist at the same time.

    CkImap imap = new CkImap();

    // Let the IMAP object also use the SSH tunnel
    success = imap.UseSshTunnel(tunnel);
    if (success == false) {
        System.out.println(imap.lastErrorText());
        return;
        }

    // Connect to an IMAP server via the already established SSH tunnel.
    // Because the SSH tunnel has been previously setup,
    // this does not establish a direct connection with the IMAP
    // server.  It directs the SSH server to establish the connection.

    // In this example, the IMAP server requires SSL/TLS.  The TLS connection
    // will be enclosed within the SSH tunnel.
    imap.put_Ssl(true);
    imap.put_Port(993);
    success = imap.Connect("imap.my-imap-server.com");
    if (success == false) {
        System.out.println(imap.lastErrorText());
        return;
        }

    // Authenticate with the IMAP server via the SSH tunnel.
    success = imap.Login("myLogin","myPassword");
    if (success == false) {
        System.out.println(imap.lastErrorText());
        return;
        }

    // Select an IMAP mailbox
    success = imap.SelectMailbox("Inbox");
    if (success == false) {
        System.out.println(imap.lastErrorText());
        return;
        }

    // How many messages in Inbox?
    int msgCount = imap.get_NumMessages();
    if (msgCount == 0) {
        System.out.println("No messages found.");
        return;
        }

    int upperBound = 10;
    if (msgCount < upperBound) {
        upperBound = msgCount;
        }

    // Download up to the 1st 10 messages.
    CkEmail email = new CkEmail();
    int i;
    boolean bUid = false;
    for (i = 1; i <= upperBound; i++) {

        success = imap.FetchEmail(false,i,bUid,email);
        if (success == false) {
            System.out.println(imap.lastErrorText());
            return;
            }

        System.out.println(email.ck_from());
        System.out.println(email.subject());

        }

    // Disconnect from the IMAP server.
    // The SSH tunnel remains open.
    success = imap.Disconnect();
    if (success == false) {
        System.out.println(imap.lastErrorText());
        return;
        }

    // It is possible to re-use the existing SSH tunnel for the next connection:
    success = imap.Connect("imap.my-imap-server2.com");
    if (success == false) {
        System.out.println(imap.lastErrorText());
        return;
        }

    // Review the LastErrorText to see that the connection was made via the SSH tunnel:
    System.out.println(imap.lastErrorText());

    // This closes the SSH channel, which is the connection with the IMAP server.
    // It does not close the SSH tunnel
    success = imap.Disconnect();
    if (success == false) {
        System.out.println(imap.lastErrorText());
        return;
        }

    // Finally, close the SSH tunnel.

    // Note: If other objects are using the same SSH tunnel, the tunnel is not 
    // actually closed.  It is only closed when the last object using the tunnel closes it.

    // At this point, both the imap and tunnel objects have references to the internal
    // SSH tunnel.  We need to close each.

    // This call doesn't actually close the tunnel yet, because the tunnel object still
    // holds an internal reference.
    success = imap.SshCloseTunnel();
    if (success == false) {
        System.out.println(imap.lastErrorText());
        return;
        }

    // This actually closes the SSH tunnel because it's the last object using it.
    success = tunnel.SshCloseTunnel();
    if (success == false) {
        System.out.println(tunnel.lastErrorText());
        return;
        }

    System.out.println("IMAP pre-existing SSH tunnel example completed.");
  }
}