(SQL Server) TLS Connection within SSH Tunnel (Port Forwarding)

Demonstrates using Chilkat Socket to communicate to a TLS service through an SSH tunnel. This example will connect (through a port-forwarded SSH tunnel) to the GMAIL IMAP server via TLS and will receive the greeting.

Note: The Chilkat IMAP API provides direct support for using SSH tunneling with the IMAP protocol. This example serves only to demonstrate that, in general, TLS connections can be tunneled through SSH.

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

// Important: See this note about string length limitations for strings returned by sp_OAMethod calls.
//
CREATE PROCEDURE ChilkatSample
AS
BEGIN
    DECLARE @hr int
    DECLARE @iTmp0 int
    DECLARE @sTmp0 nvarchar(4000)
    -- This example requires the Chilkat API to have been previously unlocked.
    -- See Global Unlock Sample for sample code.

    DECLARE @tunnel int
    EXEC @hr = sp_OACreate 'Chilkat_9_5_0.Socket', @tunnel OUT
    IF @hr <> 0
    BEGIN
        PRINT 'Failed to create ActiveX component'
        RETURN
    END

    DECLARE @sshHostname nvarchar(4000)
    SELECT @sshHostname = 'sftp.example.com'
    DECLARE @sshPort int
    SELECT @sshPort = 22

    -- Connect to an SSH server and establish the SSH tunnel:
    DECLARE @success int
    EXEC sp_OAMethod @tunnel, 'SshOpenTunnel', @success OUT, @sshHostname, @sshPort
    IF @success <> 1
      BEGIN
        EXEC sp_OAGetProperty @tunnel, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @tunnel
        RETURN
      END

    -- Authenticate with the SSH server via a login/password
    -- or with a public key.
    -- This example demonstrates SSH password authentication.
    EXEC sp_OAMethod @tunnel, 'SshAuthenticatePw', @success OUT, 'mySshLogin', 'mySshPassword'
    IF @success <> 1
      BEGIN
        EXEC sp_OAGetProperty @tunnel, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @tunnel
        RETURN
      END

    --  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.

    -- Connect to the GMAIL IMAP server via TLS (through the port-forwarded SSH tunnel)
    DECLARE @channel int

    DECLARE @maxWaitMs int
    SELECT @maxWaitMs = 4000
    DECLARE @useTls int
    SELECT @useTls = 1
    EXEC sp_OAMethod @tunnel, 'SshOpenChannel', @channel OUT, 'imap.gmail.com', 993, @useTls, @maxWaitMs
    EXEC sp_OAGetProperty @tunnel, 'LastMethodSuccess', @iTmp0 OUT
    IF @iTmp0 = 0
      BEGIN
        EXEC sp_OAGetProperty @tunnel, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @tunnel
        RETURN
      END

    -- If desired, visually inspect the LastErrorText to see that indeed the TLS
    -- protocol was run inside the SSH tunnel:
    EXEC sp_OAGetProperty @tunnel, 'LastErrorText', @sTmp0 OUT
    PRINT @sTmp0

    -- The first thing an IMAP server does is to send a greeting terminated with a CRLF.
    DECLARE @imapGreeting nvarchar(4000)
    EXEC sp_OAMethod @channel, 'ReceiveToCRLF', @imapGreeting OUT
    EXEC sp_OAGetProperty @channel, 'LastMethodSuccess', @iTmp0 OUT
    IF @iTmp0 <> 1
      BEGIN
        EXEC sp_OAGetProperty @channel, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @channel

        EXEC @hr = sp_OADestroy @tunnel
        RETURN
      END


    PRINT @imapGreeting

    -- Close the connection to imap.gmail.com.  This is actually closing our channel
    -- within the SSH tunnel, but keeps the tunnel open for the next port-forwarded connection.
    EXEC sp_OAMethod @channel, 'Close', @success OUT, @maxWaitMs
    IF @success <> 1
      BEGIN
        EXEC sp_OAGetProperty @channel, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @tunnel
        RETURN
      END

    EXEC @hr = sp_OADestroy @channel

    -- Finally, close the SSH tunnel.
    EXEC sp_OAMethod @tunnel, 'SshCloseTunnel', @success OUT
    IF @success <> 1
      BEGIN
        EXEC sp_OAGetProperty @tunnel, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @tunnel
        RETURN
      END


    PRINT 'TLS SSH tunneling example completed.'

    EXEC @hr = sp_OADestroy @tunnel


END
GO