dns: never return error on UDP DNS

UDP parsers should never return error as it should indicate to Suricata
that an unrecoverable error has occurred.  UDP being record based for
the most part is almost always recoverable, at least for protocols like
DNS.

rust/src/dns/dns.rs

@@ -767,11 +767,8 @@ pub unsafe extern "C" fn rs_dns_parse_request(
     stream_slice: StreamSlice, _data: *const std::os::raw::c_void,
 ) -> AppLayerResult {
     let state = cast_pointer!(state, DNSState);
-    if state.parse_request_udp(flow, stream_slice) {
+    state.parse_request_udp(flow, stream_slice);
     AppLayerResult::ok()
-    } else {
-        AppLayerResult::err()
-    }
 }
 
 #[no_mangle]
@@ -780,11 +777,8 @@ pub unsafe extern "C" fn rs_dns_parse_response(
     stream_slice: StreamSlice, _data: *const std::os::raw::c_void,
 ) -> AppLayerResult {
     let state = cast_pointer!(state, DNSState);
-    if state.parse_response_udp(flow, stream_slice) {
+    state.parse_response_udp(flow, stream_slice);
     AppLayerResult::ok()
-    } else {
-        AppLayerResult::err()
-    }
 }
 
 /// C binding parse a DNS request. Returns 1 on success, -1 on failure.