在ASP.NET Core 6中嵌入noVNC的WebSocket代理实现故障排查

我需要在.NET Web应用的iframe中嵌入noVNC控制台，我的OpenStack配置仅接收HTTP请求，但Web应用使用HTTPS协议。当在ASP.NET Web应用里用iframe展示noVNC控制台时，控制台会向我的服务器发送WSS请求，可OpenStack Horizon只支持WS请求。我编写了中间件实现HTTPS转HTTP、WSS转WS，但控制台能显示却立即断开连接，附上相关代码及问题截图：

HTTP反向代理中间件 #

namespace ReverseProxyApplication
{
    public class ReverseProxyMiddleware
    {
        private static readonly HttpClient _httpClient = new HttpClient();


        private readonly RequestDelegate _nextMiddleware;

        public ReverseProxyMiddleware(RequestDelegate nextMiddleware)
        {
            _nextMiddleware = nextMiddleware;
        }

        public async Task Invoke(HttpContext context)
        {
            var targetUri = BuildTargetUri(context.Request);

            if (targetUri != null)
            {

                
                var targetRequestMessage = CreateTargetMessage(context, targetUri);

                using (var responseMessage = await _httpClient.SendAsync(targetRequestMessage, HttpCompletionOption.ResponseHeadersRead, context.RequestAborted))
                {
                    context.Response.StatusCode = (int)responseMessage.StatusCode;
                    CopyFromTargetResponseHeaders(context, responseMessage);
                    await responseMessage.Content.CopyToAsync(context.Response.Body);
                }
                
                return;
            }

            await _nextMiddleware(context);
        }

        private HttpRequestMessage CreateTargetMessage(HttpContext context, Uri targetUri)
        {
            var requestMessage = new HttpRequestMessage();
            CopyFromOriginalRequestContentAndHeaders(context, requestMessage);

            requestMessage.RequestUri = targetUri;
            requestMessage.Headers.Host = targetUri.Host;
            requestMessage.Method = GetMethod(context.Request.Method);

            return requestMessage;
        }

        private void CopyFromOriginalRequestContentAndHeaders(HttpContext context, HttpRequestMessage requestMessage)
        {
            var requestMethod = context.Request.Method;

            if (!HttpMethods.IsGet(requestMethod) &&
              !HttpMethods.IsHead(requestMethod) &&
              !HttpMethods.IsDelete(requestMethod) &&
              !HttpMethods.IsTrace(requestMethod))
            {
                var streamContent = new StreamContent(context.Request.Body);
                requestMessage.Content = streamContent;
            }

            foreach (var header in context.Request.Headers)
            {
                requestMessage.Content?.Headers.TryAddWithoutValidation(header.Key, header.Value.ToArray());
            }
        }

        private void CopyFromTargetResponseHeaders(HttpContext context, HttpResponseMessage responseMessage)
        {
            foreach (var header in responseMessage.Headers)
            {
                context.Response.Headers[header.Key] = header.Value.ToArray();
            }

            foreach (var header in responseMessage.Content.Headers)
            {
                context.Response.Headers[header.Key] = header.Value.ToArray();
            }
            context.Response.Headers.Remove("transfer-encoding");
        }
        private static HttpMethod GetMethod(string method)
        {
            if (HttpMethods.IsDelete(method)) return HttpMethod.Delete;
            if (HttpMethods.IsGet(method)) return HttpMethod.Get;
            if (HttpMethods.IsHead(method)) return HttpMethod.Head;
            if (HttpMethods.IsOptions(method)) return HttpMethod.Options;
            if (HttpMethods.IsPost(method)) return HttpMethod.Post;
            if (HttpMethods.IsPut(method)) return HttpMethod.Put;
            if (HttpMethods.IsTrace(method)) return HttpMethod.Trace;
            return new HttpMethod(method);
        }

        private Uri BuildTargetUri(HttpRequest request)
        {
            Uri targetUri = null;

            if (request.Path.StartsWithSegments("/horizon", out var remainingPath))
            {
                targetUri = new Uri("http://192.168.66.11:6080" + remainingPath);
            }



            return targetUri;
        }
    }
}

WebSocket中间件 #

public class WebSocketMiddleware
{
    private static ConcurrentDictionary<string, WebSocket> _sockets = new ConcurrentDictionary<string, WebSocket>();

    private readonly RequestDelegate _next;

    public WebSocketMiddleware(RequestDelegate next)
    {
        _next = next;
    }

    public async Task Invoke(HttpContext context)
    {
        if (!context.WebSockets.IsWebSocketRequest)
        {
            await _next.Invoke(context);
            return;
        }
        var buffer = new ArraySegment<byte>(new byte[8192]);
        Uri targetUri = new Uri("ws://192.168.66.11:6080/" + context.Request.QueryString.Value);
        ClientWebSocket _websocketClient = new ClientWebSocket();

        await _websocketClient.ConnectAsync(targetUri, CancellationToken.None);
        // if (_websocketClient.State == WebSocketState.Open)
        // {
        //     // await _websocketClient.SendAsync(buffer, WebSocketMessageType.Binary, true, CancellationToken.None);
        //     var result = await _websocketClient.ReceiveAsync(buffer, CancellationToken.None);

        //     if (result.MessageType == WebSocketMessageType.Close)
        //     {
        //         await _websocketClient.CloseAsync(WebSocketCloseStatus.NormalClosure, null, CancellationToken.None);

        //     }
        // }

        CancellationToken ct = context.RequestAborted;
        WebSocket currentSocket = await context.WebSockets.AcceptWebSocketAsync();

        var socketId = Guid.NewGuid().ToString();

        _sockets.TryAdd(socketId, currentSocket);

        foreach (var socket in _sockets)
        {
            if (socket.Value.State != WebSocketState.Open)
            {
                continue;
            }

            await SendStringAsync(socket.Value, _websocketClient, buffer, ct);
        }





        while (true)
        {
            if (ct.IsCancellationRequested)
            {
                break;
            }

            var response = await ReceiveStringAsync(currentSocket, _websocketClient, context, ct);
            if (response != null)
            {
                if (currentSocket.State != WebSocketState.Open)
                {
                    break;
                }
                //continue;
                foreach (var socket in _sockets)
                {
                    if (socket.Value.State != WebSocketState.Open)
                    {
                        continue;
                    }

                    await SendStringAsync(socket.Value, _websocketClient, response, ct);
                }

            }



        }

        WebSocket dummy;
        _sockets.TryRemove(socketId, out dummy);

        await currentSocket.CloseAsync(WebSocketCloseStatus.NormalClosure, "Closing", ct);
        currentSocket.Dispose();
    }

    private static Task SendStringAsync(WebSocket socket, ClientWebSocket _websocketClient, ArraySegment<byte> data, CancellationToken ct = default(CancellationToken))
    {
        //var buffer = Encoding.UTF8.GetBytes(data);
        var segment = new ArraySegment<byte>(new byte[8192]);
        if (_websocketClient.State == WebSocketState.Open)
        {

            _websocketClient.ReceiveAsync(segment, CancellationToken.None);
            //_websocketClient.SendAsync(segment, WebSocketMessageType.Binary, true, CancellationToken.None);


        }
        return socket.SendAsync(segment, WebSocketMessageType.Binary, true, ct);
    }

    private static async Task<ArraySegment<byte>> ReceiveStringAsync(WebSocket socket, ClientWebSocket _websocketClient, HttpContext context, CancellationToken ct = default(CancellationToken))
    {
        var buffer = new ArraySegment<byte>(new byte[8192]);

        WebSocketReceiveResult result;
        do
        {
            ct.ThrowIfCancellationRequested();

            result = await socket.ReceiveAsync(buffer, ct);

        } while (!result.EndOfMessage);

        // Uri targetUri = new Uri("ws://192.168.66.11:6080/" + context.Request.QueryString.Value);
        //ClientWebSocket _websocketClient = new ClientWebSocket();
        //await _websocketClient.ConnectAsync(targetUri, CancellationToken.None);
        if (_websocketClient.State == WebSocketState.Open)
        {
            bool hasAllZeroes = buffer.All(singleByte => singleByte == 0);
            if (!hasAllZeroes)
                await _websocketClient.SendAsync(buffer, WebSocketMessageType.Binary, true, CancellationToken.None);
            //var myresult = await _websocketClient.ReceiveAsync(buffer, CancellationToken.None);



        }

        return buffer == new ArraySegment<byte>(new byte[8192]) ? null : buffer;

    }
}

页面加载情况 #

内容的提问来源于stack exchange，提问作者Shervin Souri