From c111675dd8788ef8ab662989b1e5a90fc04a9a56 Mon Sep 17 00:00:00 2001
From: Viktor Liu <17948409+lixmal@users.noreply.github.com>
Date: Wed, 5 Mar 2025 18:57:17 +0100
Subject: [PATCH]  [client] Handle large DNS packets in dns route resolution
 (#3441)

---
 client/internal/routemanager/dnsinterceptor/handler.go | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/client/internal/routemanager/dnsinterceptor/handler.go b/client/internal/routemanager/dnsinterceptor/handler.go
index f36285cc4..da1056e2d 100644
--- a/client/internal/routemanager/dnsinterceptor/handler.go
+++ b/client/internal/routemanager/dnsinterceptor/handler.go
@@ -160,6 +160,12 @@ func (d *DnsInterceptor) ServeDNS(w dns.ResponseWriter, r *dns.Msg) {
 		return
 	}
 
+	// set the AuthenticatedData flag and the EDNS0 buffer size to 4096 bytes to support larger dns records
+	if r.Extra == nil {
+		r.SetEdns0(4096, false)
+		r.MsgHdr.AuthenticatedData = true
+	}
+
 	client := &dns.Client{
 		Timeout: 5 * time.Second,
 		Net:     "udp",