SSL_get_verify_result - get result of peer certificate verification
 #include <openssl/ssl.h>
 long SSL_get_verify_result(const SSL *ssl);
SSL_get_verify_result() returns the result of the verification of the
  X509 certificate presented by the peer, if any.
SSL_get_verify_result() can only return one error code while the
  verification of a certificate can fail because of many reasons at the same
  time. Only the last verification error that occurred during the processing is
  available from SSL_get_verify_result().
Sometimes there can be a sequence of errors leading to the
    verification failure as reported by SSL_get_verify_result(). To get
    the errors, it is necessary to setup a verify callback via
    SSL_CTX_set_verify(3) or SSL_set_verify(3) and retrieve the
    errors from the error stack there, because once SSL_connect(3)
    returns, these errors may no longer be available.
The verification result is part of the established session and is
    restored when a session is reused.
If no peer certificate was presented, the returned result code is X509_V_OK.
  This is because no verification error occurred, it does however not indicate
  success. SSL_get_verify_result() is only useful in connection with
  SSL_get_peer_certificate(3).
The following return values can currently occur:
  - X509_V_OK
- The verification succeeded or no peer certificate was presented.
- Any other value
- Documented in openssl-verify(1).
ssl(7), SSL_set_verify_result(3),
  SSL_get_peer_certificate(3), openssl-verify(1)
Copyright 2000-2023 The OpenSSL Project Authors. All Rights Reserved.Licensed under the Apache License 2.0 (the "License").
    You may not use this file except in compliance with the License. You can
    obtain a copy in the file LICENSE in the source distribution or at
    <https://www.openssl.org/source/license.html>.