From 0a08f0efd1eab1d1770e4f00a62bd01e0d321ee5 Mon Sep 17 00:00:00 2001
From: aler9 <46489434+aler9@users.noreply.github.com>
Date: Tue, 8 Mar 2022 16:23:56 +0100
Subject: [PATCH] Make Packet.MarshalTo() thread-safe

A Marshal function shouldn't change any property of the object that is
being marshaled. Otherwise, Marshal() is non-thread safe and can't be
called by multiple goroutines in parallel.

PR #155 makes Packet.Marshal() set the Packet.Header.Padding bit when
Packet.PaddingSize is non-zero; while this is preferable from the user
point of view, it doesn't allow thread safety.

This patch fixes the issue.
---
 packet.go      | 1 -
 packet_test.go | 1 +
 2 files changed, 1 insertion(+), 1 deletion(-)

diff --git a/packet.go b/packet.go
index b3ae124..383a2bb 100644
--- a/packet.go
+++ b/packet.go
@@ -470,7 +470,6 @@ func (p Packet) Marshal() (buf []byte, err error) {
 
 // MarshalTo serializes the packet and writes to the buffer.
 func (p Packet) MarshalTo(buf []byte) (n int, err error) {
-	p.Header.Padding = p.PaddingSize != 0
 	n, err = p.Header.MarshalTo(buf)
 	if err != nil {
 		return 0, err
diff --git a/packet_test.go b/packet_test.go
index 5d19c11..6067c28 100644
--- a/packet_test.go
+++ b/packet_test.go
@@ -251,6 +251,7 @@ func TestBasic(t *testing.T) {
 				}},
 			},
 			Version:        2,
+			Padding:        true,
 			PayloadType:    96,
 			SequenceNumber: 27023,
 			Timestamp:      3653407706,