From c21c92db37b3d9a414e263026e41d84cba75ad3b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=D0=9F=D1=8B=D1=82=D0=BA=D0=BE=D0=B2=20=D0=A0=D0=BE=D0=BC?=
 =?UTF-8?q?=D0=B0=D0=BD?= <roman.pytkov@mail.ru>
Date: Wed, 17 Sep 2025 12:39:49 +0300
Subject: [PATCH] =?UTF-8?q?=D0=94=D0=BE=D0=B1=D0=B0=D0=B2=D0=BB=D0=B5?=
 =?UTF-8?q?=D0=BD=20magic-header?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 Client/TcpClient.cs | 22 ++++++++++++++++++++--
 Server/TcpServer.cs |  3 +++
 2 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/Client/TcpClient.cs b/Client/TcpClient.cs
index 592caa9..5a93a66 100644
--- a/Client/TcpClient.cs
+++ b/Client/TcpClient.cs
@@ -9,6 +9,7 @@ namespace Client;
 
 public class TcpClientWrapper : IClient
 {
+    private const uint MagicHeader = 0xDEADBEEF;
     private readonly string _host;
     private readonly int _port;
     private CancellationTokenSource _cts = new CancellationTokenSource();
@@ -16,7 +17,7 @@ public class TcpClientWrapper : IClient
     private Func<byte[], Task<Data?>>? _responseConverter;
     private TcpClient? _tcpClient;
 
-    public TcpClientWrapper(Func<byte[], Task<Data?>> responseConverter, string host = "192.168.1.117", int port = 5555)
+    public TcpClientWrapper(Func<byte[], Task<Data?>> responseConverter, string host = "localhost", int port = 5555)
     {
         _host = host;
         _port = port;
@@ -51,9 +52,26 @@ public class TcpClientWrapper : IClient
             {
                 try
                 {
+                    // Читаем magic header полностью
+                    var magicBytes = new byte[4];
+                    int totalRead = 0;
+                    while (totalRead < 4)
+                    {
+                        var read = await stream.ReadAsync(magicBytes, totalRead, 4 - totalRead, token);
+                        if (read == 0) break; // соединение закрыто
+                        totalRead += read;
+                    }
+                    if (totalRead < 4) break;
+                    var magic = BitConverter.ToUInt32(magicBytes, 0);
+                    if (magic != MagicHeader)
+                    {
+                        Console.WriteLine($"Invalid magic header: {magic:X8}, expected {MagicHeader:X8}. Skipping packet.");
+                        continue; // or break, depending on policy
+                    }
+
                     // Читаем длину полностью
                     var lengthBytes = new byte[4];
-                    int totalRead = 0;
+                    totalRead = 0;
                     while (totalRead < 4)
                     {
                         var read = await stream.ReadAsync(lengthBytes, totalRead, 4 - totalRead, token);
diff --git a/Server/TcpServer.cs b/Server/TcpServer.cs
index 122fcc1..6032142 100644
--- a/Server/TcpServer.cs
+++ b/Server/TcpServer.cs
@@ -10,6 +10,7 @@ namespace NetworkTest;
 
 public class TcpServer : IServer
 {
+    private const uint MagicHeader = 0xDEADBEEF;
     private readonly TcpListener _listener;
     private readonly Func<long, Data?> _getData;
     private readonly Func<Data, byte[]> _prepareBytes;
@@ -69,7 +70,9 @@ public class TcpServer : IServer
                 if (data != null)
                 {
                     var bytes = _prepareBytes(data);
+                    var magicBytes = BitConverter.GetBytes(MagicHeader);
                     var lengthBytes = BitConverter.GetBytes(bytes.Length);
+                    await stream.WriteAsync(magicBytes, 0, magicBytes.Length, token);
                     await stream.WriteAsync(lengthBytes, 0, lengthBytes.Length, token);
                     await stream.WriteAsync(bytes, 0, bytes.Length, token);
                     index++;