(.NET Core C#) 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.

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// Starting in v9.5.0.49, all Chilkat classes can be unlocked at once at the beginning of a program
// by calling UnlockBundle.  It requires a Bundle unlock code.
Chilkat.Global chilkatGlob = new Chilkat.Global();
bool success = chilkatGlob.UnlockBundle("Anything for 30-day trial.");
if (success != true) {
    Debug.WriteLine(chilkatGlob.LastErrorText);
    return;
}

Chilkat.Socket tunnel = new Chilkat.Socket();

bool success;

string sshHostname = "www.my-ssh-server.com";
int sshPort = 22;

// Connect to an SSH server and establish the SSH tunnel:
success = tunnel.SshOpenTunnel(sshHostname,sshPort);
if (success != true) {
    Debug.WriteLine(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 != true) {
    Debug.WriteLine(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.

Chilkat.Imap imap = new Chilkat.Imap();

// Let the IMAP object also use the SSH tunnel
success = imap.UseSshTunnel(tunnel);
if (success != true) {
    Debug.WriteLine(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.Ssl = true;
imap.Port = 993;
success = imap.Connect("imap.my-imap-server.com");
if (success != true) {
    Debug.WriteLine(imap.LastErrorText);
    return;
}

// Authenticate with the IMAP server via the SSH tunnel.
success = imap.Login("myLogin","myPassword");
if (success != true) {
    Debug.WriteLine(imap.LastErrorText);
    return;
}

// Select an IMAP mailbox
success = imap.SelectMailbox("Inbox");
if (success != true) {
    Debug.WriteLine(imap.LastErrorText);
    return;
}

// How many messages in Inbox?
int msgCount = imap.NumMessages;
if (msgCount == 0) {
    Debug.WriteLine("No messages found.");
    return;
}

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

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

    Chilkat.Email email = imap.FetchSingle(i,bUid);
    if (imap.LastMethodSuccess == false) {
        Debug.WriteLine(imap.LastErrorText);
        return;

    }
    else {
        Debug.WriteLine(email.From);
        Debug.WriteLine(email.Subject);
        Debug.WriteLine("----");

    }

}

// Disconnect from the IMAP server.
// The SSH tunnel remains open.
success = imap.Disconnect();
if (success != true) {
    Debug.WriteLine(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 != true) {
    Debug.WriteLine(imap.LastErrorText);
    return;
}

// Review the LastErrorText to see that the connection was made via the SSH tunnel:
Debug.WriteLine(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 != true) {
    Debug.WriteLine(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 != true) {
    Debug.WriteLine(imap.LastErrorText);
    return;
}

// This actually closes the SSH tunnel because it's the last object using it.
success = tunnel.SshCloseTunnel();
if (success != true) {
    Debug.WriteLine(tunnel.LastErrorText);
    return;
}

Debug.WriteLine("IMAP pre-existing SSH tunnel example completed.");