SQL Server

Stop an SSH Tunnel Listener (StopAccepting)

Demonstrates the Chilkat SshTunnel.StopAccepting method, which stops the local listener so no new client connections are accepted. The only argument (waitForThread) selects whether to wait for the listener thread to exit. Existing forwarded clients remain connected.

Background: The distinction from CloseTunnel is the point: StopAccepting closes only the front door, leaving already-connected clients to finish their transfers undisturbed. That makes it the graceful way to drain a tunnel — stop taking new work, let existing work complete, then close — rather than cutting everyone off at once.

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-- Important: See this note about string length limitations for strings returned by sp_OAMethod calls.
--
CREATE PROCEDURE ChilkatSample
AS
BEGIN
    DECLARE @hr int
    DECLARE @sTmp0 nvarchar(4000)
    DECLARE @success int
    SELECT @success = 0

    --  Demonstrates the SshTunnel.StopAccepting method, which stops the local listener so that no new
    --  client connections are accepted.  The only argument (waitForThread) selects whether to wait for
    --  the listener thread to exit.  Existing forwarded clients remain connected.

    DECLARE @tunnel int
    EXEC @hr = sp_OACreate 'Chilkat.SshTunnel', @tunnel OUT
    IF @hr <> 0
    BEGIN
        PRINT 'Failed to create ActiveX component'
        RETURN
    END

    EXEC sp_OASetProperty @tunnel, 'DestHostname', 'db.internal.example.com'
    EXEC sp_OASetProperty @tunnel, 'DestPort', 5432

    DECLARE @sshPort int
    SELECT @sshPort = 22
    EXEC sp_OAMethod @tunnel, 'Connect', @success OUT, 'ssh.example.com', @sshPort
    IF @success = 0
      BEGIN
        EXEC sp_OAGetProperty @tunnel, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @tunnel
        RETURN
      END

    --  Normally you would not hard-code the password in source.  You should instead obtain it
    --  from an interactive prompt, environment variable, or a secrets vault.
    DECLARE @password nvarchar(4000)
    SELECT @password = 'mySshPassword'

    EXEC sp_OAMethod @tunnel, 'AuthenticatePw', @success OUT, 'mySshLogin', @password
    IF @success = 0
      BEGIN
        EXEC sp_OAGetProperty @tunnel, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @tunnel
        RETURN
      END

    DECLARE @listenPort int
    SELECT @listenPort = 1080
    EXEC sp_OAMethod @tunnel, 'BeginAccepting', @success OUT, @listenPort
    IF @success = 0
      BEGIN
        EXEC sp_OAGetProperty @tunnel, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @tunnel
        RETURN
      END

    --  ... the tunnel runs for a while ...

    --  Stop accepting NEW connections, but leave already-connected clients running.
    DECLARE @waitForThread int
    SELECT @waitForThread = 1
    EXEC sp_OAMethod @tunnel, 'StopAccepting', @success OUT, @waitForThread
    IF @success = 0
      BEGIN
        EXEC sp_OAGetProperty @tunnel, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @tunnel
        RETURN
      END

    PRINT 'The listener has stopped; existing clients continue.'

    DECLARE @waitForThreadExit int
    SELECT @waitForThreadExit = 1
    EXEC sp_OAMethod @tunnel, 'CloseTunnel', @success OUT, @waitForThreadExit
    IF @success = 0
      BEGIN
        EXEC sp_OAGetProperty @tunnel, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @tunnel
        RETURN
      END

    EXEC @hr = sp_OADestroy @tunnel


END
GO