Function c509::determine_issuer

pub(crate) fn determine_issuer(
    self_signed: bool,
    issuer: Option<RelativeDistinguishedName>,
    subject: RelativeDistinguishedName,
) -> Result<RelativeDistinguishedName>

Determine issuer of the certificate. If self-signed is true, issuer is the same as subject. Otherwise, issuer must be present.