recipients

static VALUE
ossl_pkcs7_get_recipient(VALUE self)
{
    PKCS7 *pkcs7;
    STACK_OF(PKCS7_RECIP_INFO) *sk;
    PKCS7_RECIP_INFO *si;
    int num, i;
    VALUE ary;

    GetPKCS7(self, pkcs7);
    if (PKCS7_type_is_enveloped(pkcs7))
        sk = pkcs7->d.enveloped->recipientinfo;
    else if (PKCS7_type_is_signedAndEnveloped(pkcs7))
        sk = pkcs7->d.signed_and_enveloped->recipientinfo;
    else sk = NULL;
    if (!sk) return rb_ary_new();
    if ((num = sk_PKCS7_RECIP_INFO_num(sk)) < 0) {
        ossl_raise(ePKCS7Error, "Negative number of recipient!");
    }
    ary = rb_ary_new2(num);
    for (i=0; i<num; i++) {
        si = sk_PKCS7_RECIP_INFO_value(sk, i);
        rb_ary_push(ary, ossl_pkcs7ri_new(si));
    }

    return ary;
}