WIP implementation of PKCS7::SignerInfo#add_signed_attribute

Author: rxbynerd

ext/openssl/ossl_pkcs7.c

@@ -972,6 +972,89 @@ ossl_pkcs7si_get_signed_time(VALUE self)
     return Qnil;
 }
 
+static VALUE
+ossl_pkcs7si_add_signed_attribute(VALUE self, VALUE oid, VALUE value) {
+    // PKCS7_add_signed_attribute(PKCS7_SIGNER_INFO *si, int nid, int attrtype, void *value)
+    //
+    // argument sources:
+    // si       - signer_info from OpenSSL, OpenSSL::PKCS7#signers.first, then rubyobj -> OpenSSL struct
+    // nid      - "numerical id" of OID, how to pivot from OpenSSL::ASN1::ObjectId???
+    //          - nightmare
+    //          - ObjectId has little connection with reality, it's a subclass of Primitive
+    // attrtype - "and it adds a new ASN.1 ANY object of type attrtype with the given value to the new attribute."
+    //          - what is this?
+    // value    - void PTR, ossl_asn1_get_asn1type has a case statement that produces a correct value
+
+    PKCS7_SIGNER_INFO *p7si;
+    ASN1_OBJECT *a1obj;
+    ASN1_TYPE *value_as_type; // hacks to use ossl_asn1_get_asn1type's case statement
+    int nid, tag = 0;
+
+    GetPKCS7si(self, p7si);
+
+    // convert OpenSSL::ASN1::ObjectId to a nid
+    a1obj = obj_to_asn1obj(ossl_asn1_get_value(oid)); // TODO: error check
+    nid = OBJ_obj2nid(a1obj);                         // TODO: error check (NID_undef)
+                                                      // it's completely possible someone's using an unknown NID here
+                                                      // we should raise an informative error if this happens
+
+    // so about attrtype...
+    // i'm assuming this would be something like "OpenSSL::ASN1::Sequence" in Ruby
+    // we can determine attrtype from the "value", as essentially the "value" is an attrtype plus value
+    // so attrtype is eventually passed into ASN1_TYPE_set
+    // ASN1_type_set docs makes explicit references to "V_ASN1_SEQUENCE"/"V_ASN1_BOOLEAN"/"V_ASN1_OTHER"
+    // so i'm now pretty convinced i should be able to get this from a1obj
+
+    // though should we use ossl_asn1_get_tag?
+    // ossl_asn1_tag takes VALUE obj -> int
+    tag = ossl_asn1_tag(value); // TODO: error check
+
+    // how tf do we go from value -> ruby -> openssl somehow? -> "value pointer"
+    // maybe this:
+    // value = ossl_asn1_get_value(obj); // no, becaue value is a ruby — ossl_asn1_get_asn1type might have something useful
+
+    // struct asn1_object_st {
+    //   const char *sn, *ln;
+    //   int nid;
+    //   int length;
+    //   const unsigned char *data;
+    //   int flags;
+    // }
+
+
+    // "void *value" goes PKCS7_signed_attribute -> add_attribute -> X509_ATTRIBUTE_create (x_attrib.c)
+    // -> ASN1_TYPE_set(val, atrtype, value)
+    // -> a->value.ptr = value;
+    //    a is an ASN1_TYPE struct (asn1_type_st)
+    //    include/openssl/asn1.h.in as:
+    //
+    // struct asn1_type_st {
+    //   int type;
+    //   union {
+    //     char *ptr;
+    //     // a bunch of other specifically typed attributes like:
+    //     ASN1_BOOLEAN boolean;
+    //     ASN1_UNIVERSALSTRING *universalstring;
+    //   }
+    // very unclear on if this matters though?
+    //
+    // so what do we need? i'm still no closer to actually answering that question
+    // i can get an ASN1_OBJECT but that's still not much use to me
+    //
+    // i can actually get an ASN1_TYPE from ossl_asn1_get_asn1type, which calls
+    // ASN1_TYPE_set under the hood via a crazy case statement.
+    value_as_type = ossl_asn1_get_asn1type(value);
+
+    // method sig would be .add_signed_attribute(oid/type, value)
+    // where ObjectId is actually a Primitive (???) so how do I handle that?
+    // both oid and value are ultimately primitives tbh
+    PKCS7_add_signed_attribute(p7si, nid, tag, value_as_type.value);
+
+    // return the value of the attribute we've just stuck in
+    return value;
+}
+
+
 /*
  * RECIPIENT INFO
  */
@@ -1090,6 +1173,7 @@ Init_ossl_pkcs7(void)
     rb_define_method(cPKCS7Signer, "issuer", ossl_pkcs7si_get_issuer, 0);
     rb_define_method(cPKCS7Signer, "serial", ossl_pkcs7si_get_serial,0);
     rb_define_method(cPKCS7Signer,"signed_time",ossl_pkcs7si_get_signed_time,0);
+    rb_define_method(cPKCS7Signer, "add_signed_attribute", ossl_pkcs7si_add_signed_attribute, 2);
 
     cPKCS7Recipient = rb_define_class_under(cPKCS7,"RecipientInfo",rb_cObject);
     rb_define_alloc_func(cPKCS7Recipient, ossl_pkcs7ri_alloc);