From 911b20ebb5898ce111e7c31cd1801e2534e2a3c6 Mon Sep 17 00:00:00 2001
From: Bond_009 <bond.009@outlook.com>
Date: Wed, 27 Apr 2022 11:19:20 +0200
Subject: [PATCH] Avoid byte[] allocation for IPAddressUtil.IsMulticast

Ping.RawSocket his its own inline implementaion of this, maybe this
should be consolidated somewhere?
src/libraries/System.Net.Ping/src/System/Net/NetworkInformation/Ping.RawSocket.cs
L101
---
 .../src/System/Net/NetworkInformation/IPAddressUtil.cs        | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/libraries/System.Net.NetworkInformation/src/System/Net/NetworkInformation/IPAddressUtil.cs b/src/libraries/System.Net.NetworkInformation/src/System/Net/NetworkInformation/IPAddressUtil.cs
index 6f7081026cb86f..c2e776a07bee0c 100644
--- a/src/libraries/System.Net.NetworkInformation/src/System/Net/NetworkInformation/IPAddressUtil.cs
+++ b/src/libraries/System.Net.NetworkInformation/src/System/Net/NetworkInformation/IPAddressUtil.cs
@@ -20,7 +20,9 @@ public static bool IsMulticast(IPAddress address)
             }
             else
             {
-                byte firstByte = address.GetAddressBytes()[0];
+#pragma warning disable CS0618 // using Obsolete Address API because it's the more efficient option in this case
+                byte firstByte = (byte)address.Address;
+#pragma warning restore CS0618
                 return firstByte >= 224 && firstByte <= 239;
             }
         }