(Node.js) 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.

Install Chilkat for Node.js and Electron using npm at Chilkat npm packages for Node.js Chilkat npm packages for Electron on Windows, Linux, MacOS

var os = require('os');
if (os.platform() == 'win32') {  
  var chilkat = require('@chilkat/ck-node23-win64'); 
} else if (os.platform() == 'linux') {
    if (os.arch() == 'arm') {
        var chilkat = require('@chilkat/ck-node23-linux-arm');
    } else if (os.arch() == 'arm64') {
        var chilkat = require('@chilkat/ck-node23-linux-arm64');
    } else {
        var chilkat = require('@chilkat/ck-node23-linux-x64');
    }
} else if (os.platform() == 'darwin') {
  var chilkat = require('@chilkat/ck-node23-mac-universal');
}

function chilkatExample() {

    // 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.
    var chilkatGlob = new chilkat.Global();
    var success = chilkatGlob.UnlockBundle("Anything for 30-day trial.");
    if (success !== true) {
        console.log(chilkatGlob.LastErrorText);
        return;
    }

    var tunnel = new chilkat.Socket();

    var success;

    var sshHostname = "sftp.example.com";
    var sshPort = 22;

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

    var imap = new chilkat.Imap();

    // Let the IMAP object also use the SSH tunnel
    success = imap.UseSshTunnel(tunnel);
    if (success !== true) {
        console.log(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) {
        console.log(imap.LastErrorText);
        return;
    }

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

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

    // How many messages in Inbox?
    var msgCount = imap.NumMessages;
    if (msgCount == 0) {
        console.log("No messages found.");
        return;
    }

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

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

        // email: Email
        var email = imap.FetchSingle(i,bUid);
        if (imap.LastMethodSuccess == false) {
            console.log(imap.LastErrorText);
            return;

        }
        else {
            console.log(email.From);
            console.log(email.Subject);
            console.log("----");

        }

    }

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

    // Review the LastErrorText to see that the connection was made via the SSH tunnel:
    console.log(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) {
        console.log(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) {
        console.log(imap.LastErrorText);
        return;
    }

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

    console.log("IMAP pre-existing SSH tunnel example completed.");

}

chilkatExample();