Authentication error when SignalR tries to negotiate on HubConnection.StartAsync - signalr

Question

I have a blazor server side web app that uses AAD for authentication. I have added SignalR to it according to the guidance. It starts up fine, but when I try to connect using the following code:
var hubUrl = _navigationManager.ToAbsoluteUri("messaging");
hubConnection = new HubConnectionBuilder()
.WithUrl(hubUrl)
.Build();
await hubConnection.StartAsync();
I get an exception. This the console debug trace:
[INF] Request finished HTTP/2 GET https://localhost:5001/css/insight-icons/fonts/Insight.woff2 - - - 304 - font/woff2 3.1879ms
[INF] Request starting HTTP/1.1 POST https://localhost:5001/messaging/negotiate?negotiateVersion=1 - 0
[INF] OpenIdConnect was not authenticated. Failure message: Not authenticated
[INF] Authorization failed. These requirements were not met:
DenyAnonymousAuthorizationRequirement: Requires an authenticated user.
[INF] AuthenticationScheme: OpenIdConnect was challenged.
[INF] Request finished HTTP/1.1 POST https://localhost:5001/messaging/negotiate?negotiateVersion=1 - 0 - 302 0 - 962.8463ms
As mentioned I am logged in and authenticated using AAD.
Any suggestions as to what I am doing wrong of what is missing?

Answer 1

Note the token config:
hubConnection = new HubConnectionBuilder()
.WithUrl(hubUrl), options =>
{
options.AccessTokenProvider = async () =>
{
var accessTokenResult = await AccessTokenProvider.RequestAccessToken();
accessTokenResult.TryGetToken(out var accessToken);
var token = accessToken.Value;
return token;
};
})
.Build();
You should also configure the middleware one the server to add the tokens to requests going to the hub. (Not required to start the connection)
services.TryAddEnumerable(
ServiceDescriptor.Singleton<IPostConfigureOptions<JwtBearerOptions>,ConfigureJwtBearerOptions>());
ConfigureJwtBearerOptions.cs (Change the endpoint)
public class ConfigureJwtBearerOptions : IPostConfigureOptions<JwtBearerOptions>
{
public void PostConfigure(string name, JwtBearerOptions options)
{
var originalOnMessageReceived = options.Events.OnMessageReceived;
options.Events.OnMessageReceived = async context =>
{
await originalOnMessageReceived(context);
if (string.IsNullOrEmpty(context.Token))
{
var accessToken = context.Request.Query["access_token"];
var requestPath = context.HttpContext.Request.Path;
var endPoint = $"/chathub";
if (!string.IsNullOrEmpty(accessToken) &&
requestPath.StartsWithSegments(endPoint))
{
context.Token = accessToken;
}
}
};
}
}