From c8773151c85620688029d66536ed8d47b42ef2c6 Mon Sep 17 00:00:00 2001
From: Jukka Taimisto <jtaimisto@gmail.com>
Date: Thu, 17 Feb 2022 14:30:16 +0200
Subject: [PATCH] Add unit test to verify OPT record is skipped and rest are
 read

---
 dnsutils/dns_test.go | 52 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 52 insertions(+)

diff --git a/dnsutils/dns_test.go b/dnsutils/dns_test.go
index aa02df07..3c9f38bc 100644
--- a/dnsutils/dns_test.go
+++ b/dnsutils/dns_test.go
@@ -721,6 +721,58 @@ func TestDecodeRdataSOA_Minimization(t *testing.T) {
 		t.Errorf(" error returned: %v", err)
 	}
 }
+func TestDecodeQuestion_SkipOpt(t *testing.T) {
+	payload := []byte{
+		0x43, 0xac, 0x01, 0x00, 0x00, 0x01, 0x00, 0x02,
+		0x00, 0x00, 0x00, 0x00,
+		// Query section
+		0x0f, 0x64, 0x6e, 0x73,
+		0x74, 0x61, 0x70, 0x63, 0x6f, 0x6c, 0x6c, 0x65,
+		0x63, 0x74, 0x6f, 0x72, 0x04, 0x74, 0x65, 0x73,
+		0x74, 0x00, 0x00, 0x01, 0x00, 0x01,
+		// Answer Resource Records
+		0x0f, 0x64,
+		0x6e, 0x73, 0x74, 0x61, 0x70, 0x63, 0x6f, 0x6c,
+		0x6c, 0x65, 0x63, 0x74, 0x6f, 0x72, 0x04, 0x74,
+		0x65, 0x73, 0x74, 0x00,
+		// type OPT, class IN
+		0x00, 0x29, 0x00, 0x01,
+		// TTL
+		0x00, 0x00, 0x0e, 0x10,
+		// RDLENGTH
+		0x00, 0x01,
+		//RDATA
+		0x01,
+		// 2nd resource record
+		0x0f, 0x64,
+		0x6e, 0x73, 0x74, 0x61, 0x70, 0x63, 0x6f, 0x6c,
+		0x6c, 0x65, 0x63, 0x74, 0x6f, 0x72, 0x04, 0x74,
+		0x65, 0x73, 0x74, 0x00,
+		// type A, class IN
+		0x00, 0x01, 0x00, 0x01,
+		// TTL
+		0x00, 0x00, 0x0e, 0x10,
+		// RDLENGTH
+		0x00, 0x04,
+		// RDATA
+		0x7f, 0x00, 0x00, 0x01,
+	}
+	_, _, offsetrr, err := DecodeQuestion(payload)
+	if err != nil {
+		t.Errorf("Unexpected error decoding question: %v", err)
+	}
+
+	answer, _, erra := DecodeAnswer(2, offsetrr, payload)
+	if erra != nil {
+		t.Errorf("Unexpected error decoding answer: %v", erra)
+	}
+	if len(answer) != 1 {
+		t.Fatalf("Expected answer to contain one resource record, got %d", len(answer))
+	}
+	if answer[0].Rdatatype != RdatatypeToString(0x01) || answer[0].Rdata != "127.0.0.1" {
+		t.Errorf("unexpected answer %s %s, expected A 127.0.0.1", answer[0].Rdatatype, answer[0].Rdata)
+	}
+}
 
 func TestDecodeDns_HeaderTooShort(t *testing.T) {
 	decoded := []byte{183, 59}