Allow users of AsyncDnsServer to set a default RCODE

This is mostly for cases where no zone is set up and all response stubs
come to response handler with REFUSED as RCODE.

This commit allows to override the RCODE before QueryContext is passed
to response handlers.

diff --git a/bin/tests/system/isctest/asyncserver.py b/bin/tests/system/isctest/asyncserver.py
index f25ca4192b0645958aead4924e369f02cce34f2e..b74b90c1051154cc59db44841b9714803621d06d 100644 (file)
--- a/bin/tests/system/isctest/asyncserver.py
+++ b/bin/tests/system/isctest/asyncserver.py
@@ -734,6 +734,7 @@ class AsyncDnsServer(AsyncServer):
 
     def __init__(
         self,
+        default_rcode: dns.rcode.Rcode = dns.rcode.REFUSED,
         acknowledge_manual_dname_handling: bool = False,
         acknowledge_tsig_dnspython_hacks: bool = False,
     ) -> None:
@@ -742,6 +743,7 @@ class AsyncDnsServer(AsyncServer):
         self._zone_tree: _ZoneTree = _ZoneTree()
         self._connection_handler: Optional[ConnectionHandler] = None
         self._response_handlers: List[ResponseHandler] = []
+        self._default_rcode = default_rcode
         self._acknowledge_manual_dname_handling = acknowledge_manual_dname_handling
         self._acknowledge_tsig_dnspython_hacks = acknowledge_tsig_dnspython_hacks
 
@@ -1067,6 +1069,8 @@ class AsyncDnsServer(AsyncServer):
         """
         Yield response(s) either from response handlers or zone data.
         """
+        qctx.response.set_rcode(self._default_rcode)
+
         self._prepare_response_from_zone_data(qctx)
 
         response_handled = False
@@ -1113,8 +1117,8 @@ class AsyncDnsServer(AsyncServer):
             qctx.zone = zone
             return False
 
-        if not qctx.response.answer:
-            qctx.response.set_rcode(dns.rcode.REFUSED)
+        # RCODE is already set to self._default_rcode, i.e. REFUSED by default;
+        # it should also not be changed when following a CNAME chain
         return True
 
     def _delegation_response(self, qctx: QueryContext) -> bool:
@@ -1192,6 +1196,7 @@ class AsyncDnsServer(AsyncServer):
         if not cname:
             return False
 
+        qctx.response.set_rcode(dns.rcode.NOERROR)
         cname_rrset = dns.rrset.RRset(qctx.current_qname, qctx.qclass, cname.rdtype)
         cname_rrset.update(cname)
         qctx.response.answer.append(cname_rrset)