From e636c10380ab8176b3f31b14fb3e8ce4a7558578 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ask=20Bj=C3=B8rn=20Hansen?= <ask@develooper.com>
Date: Mon, 30 Dec 2019 05:42:48 -0800
Subject: [PATCH] Support the zero length EDNS0 EXPIRE option (#1065)

* Support the zero length EDNS0 EXPIRE option

* EDNS0 EXPIRE: Just reference the RFC, don't link to it

Co-Authored-By: Miek Gieben <miek@miek.nl>

Co-authored-by: Miek Gieben <miek@miek.nl>
---
 edns.go | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/edns.go b/edns.go
index d244f7c6..04808d57 100644
--- a/edns.go
+++ b/edns.go
@@ -543,6 +543,10 @@ func (e *EDNS0_EXPIRE) pack() ([]byte, error) {
 }
 
 func (e *EDNS0_EXPIRE) unpack(b []byte) error {
+	if len(b) == 0 {
+		// zero-length EXPIRE query, see RFC 7314 Section 2
+		return nil
+	}
 	if len(b) < 4 {
 		return ErrBuf
 	}