B4X

Abort a Running SSH Tunnel Operation

Demonstrates the AbortCurrent property, which requests that the currently running foreground operation be aborted. It is intended to be set to true from another thread — for example, to interrupt a synchronous Connect that is waiting for an unresponsive server.

Background: A synchronous call like Connect blocks the calling thread until it finishes or times out, which is a problem when a user clicks "Cancel" or the app needs to shut down. Setting AbortCurrent from a different thread breaks the blocked operation out early, returning a failure the caller can handle. Note its scope is deliberately limited to the current foreground operation: it does not stop the background listener or terminate established tunnel clients — use StopAccepting or CloseTunnel for those.

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Dim success As Boolean = False

'  Demonstrates the SshTunnel.AbortCurrent property, which requests that the currently running
'  foreground operation be aborted.

Dim tunnel As ChilkatSshTunnel
tunnel.Initialize("tunnel")

'  AbortCurrent is intended to be set to True from ANOTHER thread to interrupt a synchronous
'  operation in progress -- for example, a Connect that is waiting for an unresponsive server.
'  It does not stop the background listener or terminate established background tunnel clients.
'  
'  The assignment below illustrates the property.  In a real application it would be set on a
'  separate thread while Connect blocks; if it becomes True, the blocked Connect returns with a
'  failure.
tunnel.AbortCurrent = False

tunnel.DestHostname = "db.internal.example.com"
tunnel.DestPort = 5432

Dim sshPort As Int = 22
success = tunnel.Connect("ssh.example.com", sshPort)
If success = False Then
    Log(tunnel.LastErrorText)
    Return
End If

Log("Connected.")

Dim waitForThreadExit As Boolean = True
success = tunnel.CloseTunnel(waitForThreadExit)
If success = False Then
    Log(tunnel.LastErrorText)
    Return
End If