PowerBuilder

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. PowerBuilder

integer li_rc
integer li_Success
oleobject loo_Tunnel
string ls_SshHostname
integer li_SshPort
oleobject loo_Imap
integer li_MsgCount
integer li_UpperBound
oleobject loo_Email
integer i
integer li_BUid

li_Success = 0

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

loo_Tunnel = create oleobject
li_rc = loo_Tunnel.ConnectToNewObject("Chilkat.Socket")
if li_rc < 0 then
    destroy loo_Tunnel
    MessageBox("Error","Connecting to COM object failed")
    return
end if

ls_SshHostname = "sftp.example.com"
li_SshPort = 22

// Connect to an SSH server and establish the SSH tunnel:
li_Success = loo_Tunnel.SshOpenTunnel(ls_SshHostname,li_SshPort)
if li_Success = 0 then
    Write-Debug loo_Tunnel.LastErrorText
    destroy loo_Tunnel
    return
end if

// 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.
li_Success = loo_Tunnel.SshAuthenticatePw("mySshLogin","mySshPassword")
if li_Success = 0 then
    Write-Debug loo_Tunnel.LastErrorText
    destroy loo_Tunnel
    return
end if

// 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.

loo_Imap = create oleobject
li_rc = loo_Imap.ConnectToNewObject("Chilkat.Imap")

// Let the IMAP object also use the SSH tunnel
li_Success = loo_Imap.UseSshTunnel(loo_Tunnel)
if li_Success = 0 then
    Write-Debug loo_Imap.LastErrorText
    destroy loo_Tunnel
    destroy loo_Imap
    return
end if

// 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.
loo_Imap.Ssl = 1
loo_Imap.Port = 993
li_Success = loo_Imap.Connect("imap.my-imap-server.com")
if li_Success = 0 then
    Write-Debug loo_Imap.LastErrorText
    destroy loo_Tunnel
    destroy loo_Imap
    return
end if

// Authenticate with the IMAP server via the SSH tunnel.
li_Success = loo_Imap.Login("myLogin","myPassword")
if li_Success = 0 then
    Write-Debug loo_Imap.LastErrorText
    destroy loo_Tunnel
    destroy loo_Imap
    return
end if

// Select an IMAP mailbox
li_Success = loo_Imap.SelectMailbox("Inbox")
if li_Success = 0 then
    Write-Debug loo_Imap.LastErrorText
    destroy loo_Tunnel
    destroy loo_Imap
    return
end if

// How many messages in Inbox?
li_MsgCount = loo_Imap.NumMessages
if li_MsgCount = 0 then
    Write-Debug "No messages found."
    destroy loo_Tunnel
    destroy loo_Imap
    return
end if

li_UpperBound = 10
if li_MsgCount < li_UpperBound then
    li_UpperBound = li_MsgCount
end if

// Download up to the 1st 10 messages.
loo_Email = create oleobject
li_rc = loo_Email.ConnectToNewObject("Chilkat.Email")

li_BUid = 0
for i = 1 to li_UpperBound

    li_Success = loo_Imap.FetchEmail(0,i,li_BUid,loo_Email)
    if li_Success = 0 then
        Write-Debug loo_Imap.LastErrorText
        destroy loo_Tunnel
        destroy loo_Imap
        destroy loo_Email
        return
    end if

    Write-Debug loo_Email.From
    Write-Debug loo_Email.Subject

next

// Disconnect from the IMAP server.
// The SSH tunnel remains open.
li_Success = loo_Imap.Disconnect()
if li_Success = 0 then
    Write-Debug loo_Imap.LastErrorText
    destroy loo_Tunnel
    destroy loo_Imap
    destroy loo_Email
    return
end if

// It is possible to re-use the existing SSH tunnel for the next connection:
li_Success = loo_Imap.Connect("imap.my-imap-server2.com")
if li_Success = 0 then
    Write-Debug loo_Imap.LastErrorText
    destroy loo_Tunnel
    destroy loo_Imap
    destroy loo_Email
    return
end if

// Review the LastErrorText to see that the connection was made via the SSH tunnel:
Write-Debug loo_Imap.LastErrorText

// This closes the SSH channel, which is the connection with the IMAP server.
// It does not close the SSH tunnel
li_Success = loo_Imap.Disconnect()
if li_Success = 0 then
    Write-Debug loo_Imap.LastErrorText
    destroy loo_Tunnel
    destroy loo_Imap
    destroy loo_Email
    return
end if

// 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.
li_Success = loo_Imap.SshCloseTunnel()
if li_Success = 0 then
    Write-Debug loo_Imap.LastErrorText
    destroy loo_Tunnel
    destroy loo_Imap
    destroy loo_Email
    return
end if

// This actually closes the SSH tunnel because it's the last object using it.
li_Success = loo_Tunnel.SshCloseTunnel()
if li_Success = 0 then
    Write-Debug loo_Tunnel.LastErrorText
    destroy loo_Tunnel
    destroy loo_Imap
    destroy loo_Email
    return
end if

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


destroy loo_Tunnel
destroy loo_Imap
destroy loo_Email