Question

When using the x509 certificate in c++ obtained using the function SSL_get_peer_certificate, which function should be used to handle the subject alternative name field of the certificate? Some certificates dont have multiple CN’s but have multiple subject alternative name. How should that be handled?

I was able to get the x509_EXTENSIONS struture.

typedef struct X509_extension_st
    {
    ASN1_OBJECT *object;
    ASN1_BOOLEAN critical;
    ASN1_OCTET_STRING *value;
    } X509_EXTENSION;

What is the difference between the object and the value pointers?

Answer 1

I guess in some of recent versions of OpenSSL, the X509_st (of which type the peer cert is) contains a field STACK_OF(GENERAL_NAME) *altname. If you are able to access it, it should solve your problem.