如何以编程方式获取X509证书中的电子邮件地址？

Question

I'm trying to get both the CN and emailAddress field from a X509 cert object in C. Currently i'm getting the CN like this:

cert_entry = X509_NAME_get_entry(X509_get_subject_name(cert), 0);
ASN1_STRING *entryData = X509_NAME_ENTRY_get_data( cert_entry );
ASN1_STRING_to_UTF8(&CN, entryData);
printf("%s",CN);

My question is how do I get the emailAddress field? I thought about parsing the string, but I'm guess there has to be a smarter way of doing that?

Answer 1

Figured it out

X509_NAME * subject_name = X509_get_subject_name(cert); 
int nid_email = OBJ_txt2nid("emailAddress"); 
X509_NAME_get_text_by_NID(subject_name, nid_email, peer_email, 256);