From 991cebb3d3f478ca89856bc57bef57d2c7c0cc63 Mon Sep 17 00:00:00 2001
From: Daniel <dhaavi@users.noreply.github.com>
Date: Fri, 25 Sep 2020 10:23:59 +0200
Subject: [PATCH] Retry send DNS response without extra section

---
 nameserver/response.go | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/nameserver/response.go b/nameserver/response.go
index 1159ce9e..1894c9b5 100644
--- a/nameserver/response.go
+++ b/nameserver/response.go
@@ -53,5 +53,14 @@ func writeDNSResponse(w dns.ResponseWriter, m *dns.Msg) (err error) {
 	}()
 
 	err = w.WriteMsg(m)
+	if err == nil {
+		// If we receive an error we might have exceeded the message size with all
+		// our extra information records. Retry again without the extra section.
+		m.Extra = nil
+		noExtraErr := w.WriteMsg(m)
+		if noExtraErr == nil {
+			log.Warningf("nameserver: failed to write dns message with extra section: %s", err)
+		}
+	}
 	return
 }