Question

In openssl, I can get the errorno for the certificate from using the code :

if(SSL_get_peer_certificate(ssl) != NULL){
    if((error = SSL_get_verify_result(ssl)) != X509_V_OK){
        std::cout << "error no = " << error << std::endl;
    }
}

But if I try to get the error string from this error like this:

std::string temp = ERR_error_string(SSL_get_verify_result(ssl), NULL) ;

all i get is:

error:00000013:lib(0):func(0):reason(19)

Is there any way to get the exact reason here?
I have loaded the error strings using this code:

SSL_load_error_strings();

But still i dont get the exact reason. And if i try to use
std::string a = ERR_reason_error_string(19);, The program crashes. What am I doing wrong?

Answer 1

Please use the function X509_verify_cert_error_string to get errors related to Verification of Certificates in OpenSSL. ERR_error_string gives error strings for other SSL lib related errors not for the certificate verification failure specific errors.

As for the crash, there is no reason code mapping to the value 19. All SSL error reason codes start from 100. So, ERR_reason_error_string must be returning NULL which is causing your code to crash.