Let decision reasons decide on the DNS reply

nameserver/response.go

@@ -0,0 +1,36 @@
+package nameserver
+
+import (
+	"github.com/miekg/dns"
+	"github.com/safing/portbase/log"
+	"github.com/safing/portmaster/nameserver/nsutil"
+	"github.com/safing/portmaster/network"
+)
+
+// sendResponse sends a response to query using w. If reasonCtx is not
+// nil and implements either the Responder or RRProvider interface then
+// those functions are used to craft a DNS response. If reasonCtx is nil
+// or does not implement the Responder interface and verdict is not set
+// to failed a ZeroIP response will be sent. If verdict is set to failed
+// then a ServFail will be sent instead.
+func sendResponse(w dns.ResponseWriter, query *dns.Msg, verdict network.Verdict, reason string, reasonCtx interface{}) {
+	responder, ok := reasonCtx.(nsutil.Responder)
+	if !ok {
+		if verdict == network.VerdictFailed {
+			responder = nsutil.ServeFail()
+		} else {
+			responder = nsutil.ZeroIP()
+		}
+	}
+
+	reply := responder.ReplyWithDNS(query, reason, reasonCtx)
+
+	if extra, ok := reasonCtx.(nsutil.RRProvider); ok {
+		rrs := extra.GetExtraRR(query, reason, reasonCtx)
+		reply.Extra = append(reply.Extra, rrs...)
+	}
+
+	if err := w.WriteMsg(reply); err != nil {
+		log.Errorf("nameserver: failed to send response: %s", err)
+	}
+}