DataFlex

Upgrade a Plain TCP Connection to TLS

Demonstrates Socket.ConvertToSsl, which upgrades an already-connected plain TCP socket to TLS by performing a client-side TLS handshake over the existing connection.

Background. This supports STARTTLS-style upgrades, where a protocol begins in plaintext and switches to TLS at a defined point. Perform the protocol-specific negotiation first, then call ConvertToSsl.

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DataFlex

Use ChilkatAx-win32.pkg

Procedure Test
    Boolean iSuccess
    Handle hoSocket
    Boolean iBTls
    Integer iMaxWaitMs
    String sTemp1

    Move False To iSuccess

    Get Create (RefClass(cComChilkatSocket)) To hoSocket
    If (Not(IsComObjectCreated(hoSocket))) Begin
        Send CreateComObject of hoSocket
    End

    //  Connect as plain TCP (no TLS yet).
    Move False To iBTls
    Move 5000 To iMaxWaitMs
    Get ComConnect Of hoSocket "example.com" 5000 iBTls iMaxWaitMs To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoSocket To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    //  At the point where the application protocol permits a STARTTLS-style upgrade, perform any required
    //  negotiation, then upgrade the existing connection to TLS with a client-side handshake.
    Get ComConvertToSsl Of hoSocket To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoSocket To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Showln "Connection upgraded to TLS."


End_Procedure