From 82f52b21eefa4ba7b07b4b31ae828cea08c872fa Mon Sep 17 00:00:00 2001
From: Tom Deseyn <tom.deseyn@gmail.com>
Date: Mon, 4 Jan 2021 10:06:26 +0100
Subject: [PATCH] Fix NullReferenceException in StartReceive method (#39)

---
 src/Tmds.MDns/NetworkInterfaceHandler.cs | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/src/Tmds.MDns/NetworkInterfaceHandler.cs b/src/Tmds.MDns/NetworkInterfaceHandler.cs
index 3403e88..58cbdc1 100644
--- a/src/Tmds.MDns/NetworkInterfaceHandler.cs
+++ b/src/Tmds.MDns/NetworkInterfaceHandler.cs
@@ -126,9 +126,14 @@ internal void Send(IList<ArraySegment<byte>> packets)
         {
             try
             {
+                var socket = _socket;
+                if (socket == null)
+                {
+                    return;
+                }
                 foreach (ArraySegment<byte> segment in packets)
                 {
-                    _socket.SendTo(segment.Array, segment.Offset, segment.Count, SocketFlags.None, IPv4EndPoint);
+                    socket.SendTo(segment.Array, segment.Offset, segment.Count, SocketFlags.None, IPv4EndPoint);
                 }
             }
             catch
@@ -194,7 +199,7 @@ private void OnReceive(IAsyncResult ar)
             lock (this)
             {
 #if NETSTANDARD1_3
-                if (args.SocketError != SocketError.Success)
+                if (args.SocketError != SocketError.Success || _socket == null)
                 {
                     return;
                 }
@@ -239,7 +244,7 @@ private void OnReceive(IAsyncResult ar)
                                 }
                             }
                         }
-                    }
+                    }
                     if (header.IsResponse && header.IsNoError)
                     {
                         for (int i = 0; i < header.QuestionCount; i++)