unction is used to control the behaviour when the SSL_VERIFY_PEER flag is set. It must be supplied by the application and receives two arguments: <b>preverify_ok</b> indicates, whether the verification of the certificate in question was passed (preverify_ok=1) or not (preverify_ok=0). <b>x509_ctx</b> is a pointer to the complete context used for the certificate chain verification.</p>

<p>The certificate chain is checked starting with the deepest nesting level (the root CA certificate) and worked upward to 