Wrong certificate verification

When connecting to a database server with a self signed certificate X509_get_verify_result returns X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT_LOCALLY on Windows.

Even if a fingerprint was specified the verification aborts and connection will be closed.
The code only checks for self signed error codes.

Solution: Instead of checking the last error by X509_get_verify_result, we need to register a callback function, which checks if a self signed error occured (SSL_CTX_set_verify).