带有异步/等待的 Socket.DuplicateAndClose 失败并显示 E_INVALIDARG

Question

我在将 Socket.DuplicateAndClose 与 C# 的 async/await 功能结合使用时遇到了问题。我已将问题隔离为一个最小的测试用例，如下所示。请注意，使用writer.WriteLine 而不是WriteLineAsync（和Flush 而不是FlushAsync）可以使程序成功而不会出错。但是，引入 async/await 会在 WriteLineAsync("Second socket") 行引发异常。

对于相当长的最小测试用例表示歉意，它尽可能小。

这是 .net 中的错误吗？还是我做错了什么？

using System;
using System.Diagnostics;
using System.IO;
using System.Net;
using System.Net.Sockets;
using System.Threading;
using System.Threading.Tasks;

namespace SocketTest
{
    class Program
    {
        // Simple hosting socket, not actually part of the problem, just something to connect to in Main()
        static void HostSocket(object dummy)
        {
            var listen = new TcpListener(IPAddress.Any, 12345);
            listen.Start();
            var client = listen.AcceptTcpClient();
            listen.Stop();
            var reader = new StreamReader(client.GetStream());
            while (true)
            {
                string line;
                try
                {
                    line = reader.ReadLine();
                }
                catch (Exception e)
                {
                    Console.WriteLine("Server exception:");
                    Console.WriteLine(e);
                    break;
                }
                if (line == null)
                    break;
                Console.WriteLine("Server: " + line);
            }
            reader.Dispose();
            Console.WriteLine("Server closed");
        }

        // The main problem
        static async Task RealMain()
        {
            // Connect to localhost and write a line to it. This works.
            var client = new TcpClient("127.0.0.1", 12345);
            var writer = new StreamWriter(client.GetStream());
            await writer.WriteLineAsync("First socket");
            await writer.FlushAsync();
            // Duplicate the socket with Socket.DuplicateAndClose, passing the current PID
            var info = client.Client.DuplicateAndClose(Process.GetCurrentProcess().Id);
            // Close() must be after Duplicate, otherwise ObjectDisposedException
            writer.Close();
            // Create a TcpClient using the SocketInformation struct obtained from DuplicateAndClose
            var second = new TcpClient();
            second.Client = new Socket(info);
            writer = new StreamWriter(second.GetStream());
            // Write the second line from the new socket
            await writer.WriteLineAsync("Second socket"); // EXCEPTION HERE
            await writer.FlushAsync();
            writer.Close();
        }

        // Boot the server and then start the client
        static void Main(string[] args)
        {
            new Thread(HostSocket) { IsBackground = true }.Start();
            Thread.Sleep(100);
            RealMain().Wait();
            Console.ReadKey(true);
        }
    }
}

例外是：

System.AggregateException was unhandled
  HResult=-2146233088
  Message=One or more errors occurred.
  Source=mscorlib
  StackTrace:
       at System.Threading.Tasks.Task.ThrowIfExceptional(Boolean includeTaskCanceledExceptions)
       at System.Threading.Tasks.Task.Wait(Int32 millisecondsTimeout, CancellationToken cancellationToken)
       at System.Threading.Tasks.Task.Wait()
       at SocketTest.Program.Main(String[] args) in c:\users\khyperia\documents\visual studio 2015\Projects\SocketTest\Program.cs:line 69
       at System.AppDomain._nExecuteAssembly(RuntimeAssembly assembly, String[] args)
       at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args)
       at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
       at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
       at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
       at System.Threading.ThreadHelper.ThreadStart()
  InnerException: 
       HResult=-2146232800
       Message=Unable to write data to the transport connection: The parameter is incorrect. (Exception from HRESULT: 0x80070057 (E_INVALIDARG)).
       Source=System
       StackTrace:
            at System.Net.Sockets.NetworkStream.BeginWrite(Byte[] buffer, Int32 offset, Int32 size, AsyncCallback callback, Object state)
            at System.IO.Stream.<BeginEndWriteAsync>b__16(Stream stream, ReadWriteParameters args, AsyncCallback callback, Object state)
            at System.Threading.Tasks.TaskFactory`1.FromAsyncTrim[TInstance,TArgs](TInstance thisRef, TArgs args, Func`5 beginMethod, Func`3 endMethod)
            at System.IO.Stream.BeginEndWriteAsync(Byte[] buffer, Int32 offset, Int32 count)
            at System.IO.Stream.WriteAsync(Byte[] buffer, Int32 offset, Int32 count, CancellationToken cancellationToken)
            at System.IO.Stream.WriteAsync(Byte[] buffer, Int32 offset, Int32 count)
            at System.IO.StreamWriter.<FlushAsyncInternal>d__1e.MoveNext()
         --- End of stack trace from previous location where exception was thrown ---
            at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
            at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
            at System.Runtime.CompilerServices.TaskAwaiter.GetResult()
            at SocketTest.Program.<RealMain>d__1.MoveNext() in c:\users\khyperia\documents\visual studio 2015\Projects\SocketTest\Program.cs:line 60
       InnerException: 
            HResult=-2147024809
            Message=The parameter is incorrect. (Exception from HRESULT: 0x80070057 (E_INVALIDARG))
            Source=mscorlib
            StackTrace:
                 at System.Threading.ThreadPool.BindIOCompletionCallbackNative(IntPtr fileHandle)
                 at System.Threading.ThreadPool.BindHandle(SafeHandle osHandle)
                 at System.Net.Sockets.Socket.BindToCompletionPort()
                 at System.Net.Sockets.BaseOverlappedAsyncResult.SetUnmanagedStructures(Object objectsToPin)
                 at System.Net.Sockets.OverlappedAsyncResult.SetUnmanagedStructures(Byte[] buffer, Int32 offset, Int32 size, SocketAddress socketAddress, Boolean pinSocketAddress)
                 at System.Net.Sockets.Socket.DoBeginSend(Byte[] buffer, Int32 offset, Int32 size, SocketFlags socketFlags, OverlappedAsyncResult asyncResult)
                 at System.Net.Sockets.Socket.BeginSend(Byte[] buffer, Int32 offset, Int32 size, SocketFlags socketFlags, SocketError& errorCode, AsyncCallback callback, Object state)
                 at System.Net.Sockets.Socket.BeginSend(Byte[] buffer, Int32 offset, Int32 size, SocketFlags socketFlags, AsyncCallback callback, Object state)
                 at System.Net.Sockets.NetworkStream.BeginWrite(Byte[] buffer, Int32 offset, Int32 size, AsyncCallback callback, Object state)
            InnerException: 

Answer 1

根据MSDN：

如果创建套接字的进程使用异步方法（BeginReceive 或 BeginSend），该进程必须首先将 UseOnlyOverlappedIO 属性设置为 true；否则，套接字会绑定到创建进程的完成端口，这可能会导致目标进程抛出 ArgumentNullException。

虽然不是ArgumentNullException抛出的，试试这个：

var info = client.Client.DuplicateAndClose(Process.GetCurrentProcess().Id);
info.Options |= SocketInformationOptions.UseOnlyOverlappedIO;