(Go) 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.

Note: This example requires Chilkat v11.0.0 or greater.

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    success := false

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

    tunnel := Socket_Ref.html">chilkat.NewSocket()

    sshHostname := "sftp.example.com"
    sshPort := 22

    // Connect to an SSH server and establish the SSH tunnel:
    success = tunnel.SshOpenTunnel(sshHostname,sshPort)
    if success == false {
        fmt.Println(tunnel.LastErrorText())
        tunnel.DisposeSocket()
        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 {
        fmt.Println(tunnel.LastErrorText())
        tunnel.DisposeSocket()
        return
    }

    // OK, the SSH tunnel is setup.  Now open a channel within the tunnel.
    // Once the channel is obtained, the Socket_Ref.html">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.

    imap := Imap_Ref.html">chilkat.NewImap()

    // Let the IMAP object also use the SSH tunnel
    success = imap.UseSshTunnel(tunnel)
    if success == false {
        fmt.Println(imap.LastErrorText())
        tunnel.DisposeSocket()
        imap.DisposeImap()
        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.SetSsl(true)
    imap.SetPort(993)
    success = imap.Connect("imap.my-imap-server.com")
    if success == false {
        fmt.Println(imap.LastErrorText())
        tunnel.DisposeSocket()
        imap.DisposeImap()
        return
    }

    // Authenticate with the IMAP server via the SSH tunnel.
    success = imap.Login("myLogin","myPassword")
    if success == false {
        fmt.Println(imap.LastErrorText())
        tunnel.DisposeSocket()
        imap.DisposeImap()
        return
    }

    // Select an IMAP mailbox
    success = imap.SelectMailbox("Inbox")
    if success == false {
        fmt.Println(imap.LastErrorText())
        tunnel.DisposeSocket()
        imap.DisposeImap()
        return
    }

    // How many messages in Inbox?
    msgCount := imap.NumMessages()
    if msgCount == 0 {
        fmt.Println("No messages found.")
        tunnel.DisposeSocket()
        imap.DisposeImap()
        return
    }

    upperBound := 10
    if msgCount < upperBound {
        upperBound = msgCount
    }

    // Download up to the 1st 10 messages.
    email := Email_Ref.html">chilkat.NewEmail()
    var i int
    bUid := false
    for i = 1; i <= upperBound; i++ {

        success = imap.FetchEmail(false,i,bUid,email)
        if success == false {
            fmt.Println(imap.LastErrorText())
            tunnel.DisposeSocket()
            imap.DisposeImap()
            email.DisposeEmail()
            return
        }

        fmt.Println(email.From())
        fmt.Println(email.Subject())

    }

    // Disconnect from the IMAP server.
    // The SSH tunnel remains open.
    success = imap.Disconnect()
    if success == false {
        fmt.Println(imap.LastErrorText())
        tunnel.DisposeSocket()
        imap.DisposeImap()
        email.DisposeEmail()
        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 {
        fmt.Println(imap.LastErrorText())
        tunnel.DisposeSocket()
        imap.DisposeImap()
        email.DisposeEmail()
        return
    }

    // Review the LastErrorText to see that the connection was made via the SSH tunnel:
    fmt.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 {
        fmt.Println(imap.LastErrorText())
        tunnel.DisposeSocket()
        imap.DisposeImap()
        email.DisposeEmail()
        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 {
        fmt.Println(imap.LastErrorText())
        tunnel.DisposeSocket()
        imap.DisposeImap()
        email.DisposeEmail()
        return
    }

    // This actually closes the SSH tunnel because it's the last object using it.
    success = tunnel.SshCloseTunnel()
    if success == false {
        fmt.Println(tunnel.LastErrorText())
        tunnel.DisposeSocket()
        imap.DisposeImap()
        email.DisposeEmail()
        return
    }

    fmt.Println("IMAP pre-existing SSH tunnel example completed.")

    tunnel.DisposeSocket()
    imap.DisposeImap()
    email.DisposeEmail()