部署到 Prod 时，WebSocket 不能与 SignalR Core 一起使用答案

【问题标题】：WebSockets don't work with SignalR Core when deployed to Prod部署到 Prod 时，WebSocket 不能与 SignalR Core 一起使用
【发布时间】：2019-06-09 00:21:16
【问题描述】：

在 IIS 8.5 之后运行的 ASP.NET Core 2.1

SignalR 在连接时似乎没有协商子协议并且无法完成连接。从客户端发送到服务器的消息永远不会收到。

我无法将站点配置为直接从 Kestrel 提供服务，因为这是共享服务器。将传输更改为长轮询工作。我已尝试禁用 HTTPS/HSTS 重定向。

附上来自客户端和服务器的日志：

客户端日志：

Information: Normalizing 'hubs/screen' to 'https://<url>/hubs/screen'.
Utils.ts:173 Information: WebSocket connected to ws://<url>/hubs/screen?id=
...
Error: Connection disconnected with error 'Error: Server timeout elapsed without receiving a message from the server.'.<id>

服务器日志：

dbug: Microsoft.AspNetCore.Http.Connections.Internal.HttpConnectionManager[1]
      New connection <id> created.
dbug: Microsoft.AspNetCore.Http.Connections.Internal.HttpConnectionDispatcher[10]
      Sending negotiation response.
dbug: Microsoft.AspNetCore.Http.Connections.Internal.HttpConnectionDispatcher[4]
      Establishing new connection.
dbug: Microsoft.AspNetCore.SignalR.HubConnectionHandler[5]
      OnConnectedAsync started.
dbug: Microsoft.AspNetCore.Http.Connections.Internal.Transports.WebSocketsTransport[1]
      Socket opened using Sub-Protocol: '(null)'.
dbug: Microsoft.AspNetCore.Http.Connections.Internal.Transports.WebSocketsTransport[14]
      Socket connection closed prematurely.
System.Net.WebSockets.WebSocketException (0x80004005): The remote party closed the WebSocket connection without completing the close handshake. ---> System.Net.WebSockets.WebSocketException (0x80004005): The remote party closed the WebSocket connection without completing the close handshake.
   at System.Net.WebSockets.ManagedWebSocket.ThrowIfEOFUnexpected(Boolean throwOnPrematureClosure)
   at System.Net.WebSockets.ManagedWebSocket.EnsureBufferContainsAsync(Int32 minimumRequiredBytes, Boolean throwOnPrematureClosure)
   at System.Net.WebSockets.ManagedWebSocket.ReceiveAsyncPrivate[TWebSocketReceiveResultGetter,TWebSocketReceiveResult](Memory`1 payloadBuffer, CancellationToken cancellationToken, TWebSocketReceiveResultGetter resultGetter)
   at System.Net.WebSockets.ManagedWebSocket.ReceiveAsyncPrivate[TWebSocketReceiveResultGetter,TWebSocketReceiveResult](Memory`1 payloadBuffer, CancellationToken cancellationToken, TWebSocketReceiveResultGetter resultGetter)
   at System.Net.WebSockets.WebSocket.ReceiveAsync(Memory`1 buffer, CancellationToken cancellationToken)
   at Microsoft.AspNetCore.Http.Connections.Internal.Transports.WebSocketsTransport.StartReceiving(WebSocket socket)
fail: Microsoft.AspNetCore.SignalR.HubConnectionContext[5]
      Failed connection handshake.
dbug: Microsoft.AspNetCore.Http.Connections.Internal.Transports.WebSocketsTransport[4]
      Waiting for the application to finish sending data.
dbug: Microsoft.AspNetCore.Http.Connections.Internal.Transports.WebSocketsTransport[2]
      Socket closed.

【问题讨论】：

标签： asp.net-core iis-8 asp.net-core-signalr

【解决方案1】：

我发现了问题！

我们有一个自定义 IIS 模块，该模块将服务器名称 + 请求时间作为 HTTP 标头注入，这导致 SignalR 失败。（该模块可能只是盲目地注入它的头部，而不考虑 Websockets）

【讨论】：