Better filter clients connecting to Kestrel's dispatch pipes

src/Microsoft.AspNetCore.Server.Kestrel/Internal/Http/ListenerPrimary.cs

@@ -21,6 +21,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Internal.Http
         private readonly List<UvPipeHandle> _dispatchPipes = new List<UvPipeHandle>();
         private int _dispatchIndex;
         private string _pipeName;
+        private byte[] _pipeMessage;
         private IntPtr _fileCompletionInfoPtr;
         private bool _tryDetachFromIOCP = PlatformApis.IsWindows;
 
@@ -36,10 +37,12 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Internal.Http
 
         public async Task StartAsync(
             string pipeName,
+            byte[] pipeMessage,
             ServerAddress address,
             KestrelThread thread)
         {
             _pipeName = pipeName;
+            _pipeMessage = pipeMessage;
 
             if (_fileCompletionInfoPtr == IntPtr.Zero)
             {
@@ -187,7 +190,10 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Internal.Http
 
         private class PipeReadContext
         {
+            private const int _bufferLength = 16;
+
             private readonly ListenerPrimary _listener;
+            private readonly byte[] _buf = new byte[_bufferLength];
             private readonly IntPtr _bufPtr;
             private GCHandle _bufHandle;
             private int _bytesRead;
@@ -195,16 +201,16 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Internal.Http
             public PipeReadContext(ListenerPrimary listener)
             {
                 _listener = listener;
-                _bufHandle = GCHandle.Alloc(new byte[8], GCHandleType.Pinned);
+                _bufHandle = GCHandle.Alloc(_buf, GCHandleType.Pinned);
                 _bufPtr = _bufHandle.AddrOfPinnedObject();
             }
 
             public Libuv.uv_buf_t AllocCallback(UvStreamHandle dispatchPipe, int suggestedSize)
             {
-                return dispatchPipe.Libuv.buf_init(_bufPtr + _bytesRead, 8 - _bytesRead);
+                return dispatchPipe.Libuv.buf_init(_bufPtr + _bytesRead, _bufferLength - _bytesRead);
             }
 
-            public unsafe void ReadCallback(UvStreamHandle dispatchPipe, int status)
+            public void ReadCallback(UvStreamHandle dispatchPipe, int status)
             {
                 try
                 {
@@ -212,9 +218,19 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Internal.Http
 
                     _bytesRead += status;
 
-                    if (_bytesRead == 8)
+                    if (_bytesRead == _bufferLength)
                     {
-                        if (*(ulong*)_bufPtr == Constants.PipeMessage)
+                        var correctMessage = true;
+
+                        for (var i = 0; i < _bufferLength; i++)
+                        {
+                            if (_buf[i] != _listener._pipeMessage[i])
+                            {
+                                correctMessage = false;
+                            }
+                        }
+
+                        if (correctMessage)
                         {
                             _listener._dispatchPipes.Add((UvPipeHandle) dispatchPipe);
                             dispatchPipe.ReadStop();

src/Microsoft.AspNetCore.Server.Kestrel/Internal/Http/ListenerSecondary.cs

@@ -17,10 +17,8 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Internal.Http
     /// </summary>
     public abstract class ListenerSecondary : ListenerContext, IAsyncDisposable
     {
-        private static ArraySegment<ArraySegment<byte>> _pipeMessage =
-            new ArraySegment<ArraySegment<byte>>(new[] { new ArraySegment<byte>(BitConverter.GetBytes(Constants.PipeMessage)) });
-
         private string _pipeName;
+        private byte[] _pipeMessage;
         private IntPtr _ptr;
         private Libuv.uv_buf_t _buf;
         private bool _closed;
@@ -36,10 +34,12 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Internal.Http
 
         public Task StartAsync(
             string pipeName,
+            byte[] pipeMessage,
             ServerAddress address,
             KestrelThread thread)
         {
             _pipeName = pipeName;
+            _pipeMessage = pipeMessage;
             _buf = thread.Loop.Libuv.buf_init(_ptr, 4);
 
             ServerAddress = address;
@@ -104,7 +104,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Internal.Http
                 writeReq.Init(Thread.Loop);
                 writeReq.Write(
                     DispatchPipe,
-                    _pipeMessage,
+                    new ArraySegment<ArraySegment<byte>>(new [] { new ArraySegment<byte>(_pipeMessage) }),
                     (req, status2, ex, state) =>
                     {
                         req.Dispose();

src/Microsoft.AspNetCore.Server.Kestrel/Internal/Infrastructure/Constants.cs

@@ -20,9 +20,6 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Internal.Infrastructure
 
         public const string ServerName = "Kestrel";
 
-        // "Kestrel\0"
-        public const ulong PipeMessage = 0x006C65727473654B;
-
         private static int? GetECONNRESET()
         {
             if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))

src/Microsoft.AspNetCore.Server.Kestrel/Internal/KestrelEngine.cs

@@ -70,6 +70,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Internal
             try
             {
                 var pipeName = (Libuv.IsWindows ? @"\\.\pipe\kestrel_" : "/tmp/kestrel_") + Guid.NewGuid().ToString("n");
+                var pipeMessage = Guid.NewGuid().ToByteArray();
 
                 var single = Threads.Count == 1;
                 var first = true;
@@ -91,7 +92,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Internal
                             : new TcpListenerPrimary(ServiceContext);
 
                         listeners.Add(listener);
-                        listener.StartAsync(pipeName, address, thread).Wait();
+                        listener.StartAsync(pipeName, pipeMessage, address, thread).Wait();
                     }
                     else
                     {
@@ -99,7 +100,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Internal
                             ? (ListenerSecondary) new PipeListenerSecondary(ServiceContext)
                             : new TcpListenerSecondary(ServiceContext);
                         listeners.Add(listener);
-                        listener.StartAsync(pipeName, address, thread).Wait();
+                        listener.StartAsync(pipeName, pipeMessage, address, thread).Wait();
                     }
 
                     first = false;

test/Microsoft.AspNetCore.Server.KestrelTests/ListenerPrimaryTests.cs

@@ -2,6 +2,7 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
+using System.IO;
 using System.Linq;
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Hosting.Server;
@@ -10,6 +11,7 @@ using Microsoft.AspNetCore.Http.Features;
 using Microsoft.AspNetCore.Server.Kestrel;
 using Microsoft.AspNetCore.Server.Kestrel.Internal;
 using Microsoft.AspNetCore.Server.Kestrel.Internal.Http;
+using Microsoft.AspNetCore.Server.Kestrel.Internal.Infrastructure;
 using Microsoft.AspNetCore.Server.Kestrel.Internal.Networking;
 using Microsoft.AspNetCore.Testing;
 using Microsoft.Extensions.Logging;
@@ -55,12 +57,13 @@ namespace Microsoft.AspNetCore.Server.KestrelTests
             {
                 var address = ServerAddress.FromUrl("http://127.0.0.1:0/");
                 var pipeName = (libuv.IsWindows ? @"\\.\pipe\kestrel_" : "/tmp/kestrel_") + Guid.NewGuid().ToString("n");
+                var pipeMessage = Guid.NewGuid().ToByteArray();
 
                 // Start primary listener
                 var kestrelThreadPrimary = new KestrelThread(kestrelEngine);
                 await kestrelThreadPrimary.StartAsync();
                 var listenerPrimary = new TcpListenerPrimary(serviceContextPrimary);
-                await listenerPrimary.StartAsync(pipeName, address, kestrelThreadPrimary);
+                await listenerPrimary.StartAsync(pipeName, pipeMessage, address, kestrelThreadPrimary);
 
                 // Until a secondary listener is added, TCP connections get dispatched directly
                 Assert.Equal("Primary", await HttpClientSlim.GetStringAsync(address.ToString()));
@@ -70,7 +73,7 @@ namespace Microsoft.AspNetCore.Server.KestrelTests
                 var kestrelThreadSecondary = new KestrelThread(kestrelEngine);
                 await kestrelThreadSecondary.StartAsync();
                 var listenerSecondary = new TcpListenerSecondary(serviceContextSecondary);
-                await listenerSecondary.StartAsync(pipeName, address, kestrelThreadSecondary);
+                await listenerSecondary.StartAsync(pipeName, pipeMessage, address, kestrelThreadSecondary);
 
                 // Once a secondary listener is added, TCP connections start getting dispatched to it
                 Assert.Equal("Secondary", await HttpClientSlim.GetStringAsync(address.ToString()));
@@ -128,18 +131,19 @@ namespace Microsoft.AspNetCore.Server.KestrelTests
             {
                 var address = ServerAddress.FromUrl("http://127.0.0.1:0/");
                 var pipeName = (libuv.IsWindows ? @"\\.\pipe\kestrel_" : "/tmp/kestrel_") + Guid.NewGuid().ToString("n");
+                var pipeMessage = Guid.NewGuid().ToByteArray();
 
                 // Start primary listener
                 var kestrelThreadPrimary = new KestrelThread(kestrelEngine);
                 await kestrelThreadPrimary.StartAsync();
                 var listenerPrimary = new TcpListenerPrimary(serviceContextPrimary);
-                await listenerPrimary.StartAsync(pipeName, address, kestrelThreadPrimary);
+                await listenerPrimary.StartAsync(pipeName, pipeMessage, address, kestrelThreadPrimary);
 
                 // Add secondary listener
                 var kestrelThreadSecondary = new KestrelThread(kestrelEngine);
                 await kestrelThreadSecondary.StartAsync();
                 var listenerSecondary = new TcpListenerSecondary(serviceContextSecondary);
-                await listenerSecondary.StartAsync(pipeName, address, kestrelThreadSecondary);
+                await listenerSecondary.StartAsync(pipeName, pipeMessage, address, kestrelThreadSecondary);
 
                 // TCP Connections get round-robined
                 Assert.Equal("Secondary", await HttpClientSlim.GetStringAsync(address.ToString()));
@@ -199,7 +203,79 @@ namespace Microsoft.AspNetCore.Server.KestrelTests
 
             Assert.Equal(1, primaryTrace.Logger.TotalErrorsLogged);
             var errorMessage = primaryTrace.Logger.Messages.First(m => m.LogLevel == LogLevel.Error);
-            Assert.Contains("EOF", errorMessage.Exception.ToString());
+            Assert.Equal(Constants.EOF, Assert.IsType<UvException>(errorMessage.Exception).StatusCode);
+        }
+
+
+        [Fact]
+        public async Task PipeConnectionsWithWrongMessageAreLoggedAndIgnored()
+        {
+            var libuv = new Libuv();
+
+            var primaryTrace = new TestKestrelTrace();
+
+            var serviceContextPrimary = new TestServiceContext
+            {
+                Log = primaryTrace,
+                FrameFactory = context =>
+                {
+                    return new Frame<DefaultHttpContext>(new TestApplication(c =>
+                    {
+                        return c.Response.WriteAsync("Primary");
+                    }), context);
+                }
+            };
+
+            var serviceContextSecondary = new ServiceContext
+            {
+                Log = new TestKestrelTrace(),
+                AppLifetime = serviceContextPrimary.AppLifetime,
+                DateHeaderValueManager = serviceContextPrimary.DateHeaderValueManager,
+                ServerOptions = serviceContextPrimary.ServerOptions,
+                ThreadPool = serviceContextPrimary.ThreadPool,
+                FrameFactory = context =>
+                {
+                    return new Frame<DefaultHttpContext>(new TestApplication(c =>
+                    {
+                        return c.Response.WriteAsync("Secondary"); ;
+                    }), context);
+                }
+            };
+
+            using (var kestrelEngine = new KestrelEngine(libuv, serviceContextPrimary))
+            {
+                var address = ServerAddress.FromUrl("http://127.0.0.1:0/");
+                var pipeName = (libuv.IsWindows ? @"\\.\pipe\kestrel_" : "/tmp/kestrel_") + Guid.NewGuid().ToString("n");
+                var pipeMessage = Guid.NewGuid().ToByteArray();
+
+                // Start primary listener
+                var kestrelThreadPrimary = new KestrelThread(kestrelEngine);
+                await kestrelThreadPrimary.StartAsync();
+                var listenerPrimary = new TcpListenerPrimary(serviceContextPrimary);
+                await listenerPrimary.StartAsync(pipeName, pipeMessage, address, kestrelThreadPrimary);
+
+                // Add secondary listener with wrong pipe message
+                var kestrelThreadSecondary = new KestrelThread(kestrelEngine);
+                await kestrelThreadSecondary.StartAsync();
+                var listenerSecondary = new TcpListenerSecondary(serviceContextSecondary);
+                await listenerSecondary.StartAsync(pipeName, Guid.NewGuid().ToByteArray(), address, kestrelThreadSecondary);
+
+                // TCP Connections get round-robined
+                Assert.Equal("Primary", await HttpClientSlim.GetStringAsync(address.ToString()));
+                Assert.Equal("Primary", await HttpClientSlim.GetStringAsync(address.ToString()));
+                Assert.Equal("Primary", await HttpClientSlim.GetStringAsync(address.ToString()));
+
+                await listenerSecondary.DisposeAsync();
+                await kestrelThreadSecondary.StopAsync(TimeSpan.FromSeconds(1));
+
+                await listenerPrimary.DisposeAsync();
+                await kestrelThreadPrimary.StopAsync(TimeSpan.FromSeconds(1));
+            }
+
+            Assert.Equal(1, primaryTrace.Logger.TotalErrorsLogged);
+            var errorMessage = primaryTrace.Logger.Messages.First(m => m.LogLevel == LogLevel.Error);
+            Assert.IsType<IOException>(errorMessage.Exception);
+            Assert.Contains("Bad data", errorMessage.Exception.ToString());
         }
 
         private class TestApplication : IHttpApplication<DefaultHttpContext>