PureBasic

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. PureBasic

IncludeFile "CkSocket.pb"
IncludeFile "CkImap.pb"
IncludeFile "CkEmail.pb"

Procedure ChilkatExample()

    success.i = 0

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

    tunnel.i = CkSocket::ckCreate()
    If tunnel.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    sshHostname.s = "sftp.example.com"
    sshPort.i = 22

    ; Connect to an SSH server and establish the SSH tunnel:
    success = CkSocket::ckSshOpenTunnel(tunnel,sshHostname,sshPort)
    If success = 0
        Debug CkSocket::ckLastErrorText(tunnel)
        CkSocket::ckDispose(tunnel)
        ProcedureReturn
    EndIf

    ; 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 = CkSocket::ckSshAuthenticatePw(tunnel,"mySshLogin","mySshPassword")
    If success = 0
        Debug CkSocket::ckLastErrorText(tunnel)
        CkSocket::ckDispose(tunnel)
        ProcedureReturn
    EndIf

    ; 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.

    imap.i = CkImap::ckCreate()
    If imap.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    ; Let the IMAP object also use the SSH tunnel
    success = CkImap::ckUseSshTunnel(imap,tunnel)
    If success = 0
        Debug CkImap::ckLastErrorText(imap)
        CkSocket::ckDispose(tunnel)
        CkImap::ckDispose(imap)
        ProcedureReturn
    EndIf

    ; 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.
    CkImap::setCkSsl(imap, 1)
    CkImap::setCkPort(imap, 993)
    success = CkImap::ckConnect(imap,"imap.my-imap-server.com")
    If success = 0
        Debug CkImap::ckLastErrorText(imap)
        CkSocket::ckDispose(tunnel)
        CkImap::ckDispose(imap)
        ProcedureReturn
    EndIf

    ; Authenticate with the IMAP server via the SSH tunnel.
    success = CkImap::ckLogin(imap,"myLogin","myPassword")
    If success = 0
        Debug CkImap::ckLastErrorText(imap)
        CkSocket::ckDispose(tunnel)
        CkImap::ckDispose(imap)
        ProcedureReturn
    EndIf

    ; Select an IMAP mailbox
    success = CkImap::ckSelectMailbox(imap,"Inbox")
    If success = 0
        Debug CkImap::ckLastErrorText(imap)
        CkSocket::ckDispose(tunnel)
        CkImap::ckDispose(imap)
        ProcedureReturn
    EndIf

    ; How many messages in Inbox?
    msgCount.i = CkImap::ckNumMessages(imap)
    If msgCount = 0
        Debug "No messages found."
        CkSocket::ckDispose(tunnel)
        CkImap::ckDispose(imap)
        ProcedureReturn
    EndIf

    upperBound.i = 10
    If msgCount < upperBound
        upperBound = msgCount
    EndIf

    ; Download up to the 1st 10 messages.
    email.i = CkEmail::ckCreate()
    If email.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    i.i
    bUid.i = 0
    For i = 1 To upperBound

        success = CkImap::ckFetchEmail(imap,0,i,bUid,email)
        If success = 0
            Debug CkImap::ckLastErrorText(imap)
            CkSocket::ckDispose(tunnel)
            CkImap::ckDispose(imap)
            CkEmail::ckDispose(email)
            ProcedureReturn
        EndIf

        Debug CkEmail::ckFrom(email)
        Debug CkEmail::ckSubject(email)

    Next

    ; Disconnect from the IMAP server.
    ; The SSH tunnel remains open.
    success = CkImap::ckDisconnect(imap)
    If success = 0
        Debug CkImap::ckLastErrorText(imap)
        CkSocket::ckDispose(tunnel)
        CkImap::ckDispose(imap)
        CkEmail::ckDispose(email)
        ProcedureReturn
    EndIf

    ; It is possible to re-use the existing SSH tunnel for the next connection:
    success = CkImap::ckConnect(imap,"imap.my-imap-server2.com")
    If success = 0
        Debug CkImap::ckLastErrorText(imap)
        CkSocket::ckDispose(tunnel)
        CkImap::ckDispose(imap)
        CkEmail::ckDispose(email)
        ProcedureReturn
    EndIf

    ; Review the LastErrorText to see that the connection was made via the SSH tunnel:
    Debug CkImap::ckLastErrorText(imap)

    ; This closes the SSH channel, which is the connection with the IMAP server.
    ; It does not close the SSH tunnel
    success = CkImap::ckDisconnect(imap)
    If success = 0
        Debug CkImap::ckLastErrorText(imap)
        CkSocket::ckDispose(tunnel)
        CkImap::ckDispose(imap)
        CkEmail::ckDispose(email)
        ProcedureReturn
    EndIf

    ; 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 = CkImap::ckSshCloseTunnel(imap)
    If success = 0
        Debug CkImap::ckLastErrorText(imap)
        CkSocket::ckDispose(tunnel)
        CkImap::ckDispose(imap)
        CkEmail::ckDispose(email)
        ProcedureReturn
    EndIf

    ; This actually closes the SSH tunnel because it's the last object using it.
    success = CkSocket::ckSshCloseTunnel(tunnel)
    If success = 0
        Debug CkSocket::ckLastErrorText(tunnel)
        CkSocket::ckDispose(tunnel)
        CkImap::ckDispose(imap)
        CkEmail::ckDispose(email)
        ProcedureReturn
    EndIf

    Debug "IMAP pre-existing SSH tunnel example completed."


    CkSocket::ckDispose(tunnel)
    CkImap::ckDispose(imap)
    CkEmail::ckDispose(email)


    ProcedureReturn
EndProcedure