DNS64 rewriting in the right place

src/context.c

@@ -1323,6 +1323,9 @@ getdns_context_create_with_extended_memory_functions(
 	result->return_both_v4_and_v6 = 0;
 	result->return_call_reporting = 0;
 	(void) memset(result->dns64_prefix, 0, 16);
+	result->dns64_prefix[1] = 0x64;
+	result->dns64_prefix[2] = 0xff;
+	result->dns64_prefix[3] = 0x9b;
 	result->specify_class = GETDNS_RRCLASS_IN;
 
 	/* state data used to detect changes to the system config files

src/request-internal.c

@@ -721,10 +721,13 @@ _getdns_dns_req_new(getdns_context *context, getdns_eventloop *loop,
 	getdns_dns_req *result = NULL;
         uint32_t klass = context->specify_class;
 	getdns_bindata *dns64_prefix = NULL;
-	int a_aaaa_query = is_extension_set(extensions,
+	int dns64 = is_extension_set(extensions, "dns64", context->dns64);
-	    "return_both_v4_and_v6", context->return_both_v4_and_v6) &&
+	int a_aaaa_query =  (dns64 && request_type == GETDNS_RRTYPE_AAAA) ||
-	    ( request_type == GETDNS_RRTYPE_A ||
+	    ( is_extension_set( extensions, "return_both_v4_and_v6"
-	      request_type == GETDNS_RRTYPE_AAAA );
+                               , context->return_both_v4_and_v6)
+	    && (  request_type == GETDNS_RRTYPE_A
+	       || request_type == GETDNS_RRTYPE_AAAA ));
+
 	/* Reserve for the buffer at least one more byte
 	 * (to test for udp overflow) (hence the + 1),
 	 * And align on the 8 byte boundry  (hence the (x + 7) / 8 * 8)
@@ -910,7 +913,7 @@ _getdns_dns_req_new(getdns_context *context, getdns_eventloop *loop,
 	result->add_warning_for_bad_dns        = is_extension_set(extensions,
 	    "add_warning_for_bad_dns", context->add_warning_for_bad_dns);
 
-	result->dns64 = is_extension_set(extensions, "dns64", context->dns64);
+	result->dns64 = dns64;
 	if (!getdns_dict_get_bindata(extensions, "dns64_prefix", &dns64_prefix)
 	    && dns64_prefix->size == 16)
 		(void) memcpy(result->dns64_prefix, dns64_prefix->data, 16);

src/util-internal.c

@@ -563,6 +563,12 @@ _getdns_create_reply_dict(getdns_context *context, getdns_network_req *req,
 	getdns_list *bad_dns = NULL;
 	_getdns_rrset_spc answer_spc;
 	_getdns_rrset *answer;
+	uint8_t dns64_address[16];
+
+	int dns64_translate = req->owner->dns64 &&
+	    req->owner->netreqs[1] &&
+	    req->request_type == GETDNS_RRTYPE_A &&
+	    just_addrs && !just_addrs->numinuse;
 
 	if (!result)
 		goto error;
@@ -667,6 +673,14 @@ _getdns_create_reply_dict(getdns_context *context, getdns_network_req *req,
 			continue;
 
 		bin_size = rdf_iter->nxt - rdf_iter->pos;
+		if (dns64_translate && rr_type == GETDNS_RRTYPE_A) {
+			(void) memcpy(dns64_address, req->owner->dns64_prefix, 12);
+			(void) memcpy(dns64_address + 12, rdf_iter->pos, 4);
+			rr_type = GETDNS_RRTYPE_AAAA;
+			bin_size = 16;
+			bin_data = dns64_address;
+		}
+		else
 			bin_data = rdf_iter->pos;
 		if (!set_dict(&rr_dict, getdns_dict_create_with_context(context)) ||
 
@@ -1125,6 +1139,13 @@ _getdns_create_getdns_response(getdns_dns_req *completed_request)
 		if (! netreq->response_len)
 			continue;
 
+		/* Skip dns64 translation if we had IPv6 answers alread */
+		if (completed_request->dns64 &&
+		    completed_request->netreqs[1] &&
+		    netreq->request_type == GETDNS_RRTYPE_A &&
+		    just_addrs && just_addrs->numinuse)
+			continue;
+
 		if (netreq->tsig_status == GETDNS_DNSSEC_INSECURE)
 			_getdns_network_validate_tsig(netreq);
 
@@ -1138,7 +1159,6 @@ _getdns_create_getdns_response(getdns_dns_req *completed_request)
 		    netreq->dnssec_status == GETDNS_DNSSEC_BOGUS)
 			nbogus++;
 
-
 		if (! completed_request->dnssec_return_all_statuses &&
 		    ! completed_request->dnssec_return_validation_chain) {
 			if (dnssec_return_status &&