Blazor Server(.NET6)中SignalR的HubConnectionContext二次调用丢失用户信息

问题描述 #

基于Blazor Server和.NET6实现了默认身份认证功能（登录、注销、注册正常），尝试通过SignalR向特定用户发送消息时遇到问题：已实现IUserIdProvider接口获取UserId，首次启动应用时可通过connection.GetHttpContext()或connection.User.FindFirstValue(ClaimTypes.Name)获取用户信息，但导航到其他页面再次调用Hub时，HubConnectionContext丢失了用户所有信息。强制使用常量ID可正常工作，疑惑二次调用丢失信息的原因，不确定是否需要配置Cookie（首次调用可正常获取信息）。

现有代码 #

CustomUserIdProvider.cs #

public class CustomUserIdProvider : IUserIdProvider
{
    public string? GetUserId(HubConnectionContext connection)
    {
        var httpContext = connection.GetHttpContext();
        var userId = connection.User.FindFirstValue(ClaimTypes.Name);

        if (string.IsNullOrWhiteSpace(userId))
            return string.Empty;

        return userId;
    }
}

Program.cs #

// ...
builder.Services.AddSingleton<IUserIdProvider, CustomUserIdProvider>();
// ...
app.UseAuthentication();
app.UseAuthorization();

SignalR.razor #

protected override async Task OnInitializedAsync()
{
        hubConnection = new HubConnectionBuilder()
            .WithUrl(NavigationManager.ToAbsoluteUri("/notifyhub"))
        .Build();
        hubConnection.On<int, string>("ReceiveMessage", (id, message) =>
    {
        var encodedMsg = $"{id}: {message}";
        InvokeAsync(StateHasChanged);
    });

        await hubConnection.StartAsync();
}
private async Task Send()
{
        if (hubConnection is not null)
        {
            var authState = await AuthenticationStateProvider.GetAuthenticationStateAsync();
            var user = authState.User;
            authMessage = $"{user.Identity.Name} is authenticated.";
            claims = user.Claims;
            surnameMessage =
                $"Surname: {user.FindFirst(c => c.Type == ClaimTypes.Surname)?.Value}";
            await hubConnection.SendAsync("Send", user.Identity.Name, 1, "Message envoyé");
        }
}

问题原因及解决方法 #

核心原因 #

Blazor Server采用SPA式客户端导航，而非传统HTTP页面刷新。首次加载时，SignalR连接基于初始请求的HttpContext建立，自动携带了认证Cookie；但导航后重新创建的HubConnection默认不会主动携带认证凭证，导致Hub端无法识别用户身份。

解决步骤 #

1. 配置HubConnection携带认证凭证
   在构建HubConnection时，显式设置包含Cookie凭证，确保认证信息被传递：

   hubConnection = new HubConnectionBuilder()
       .WithUrl(NavigationManager.ToAbsoluteUri("/notifyhub"), options =>
       {
           options.Credentials = FetchCredentials.Include;
       })
       .WithAutomaticReconnect() // 可选：添加自动重连，提升连接稳定性
       .Build();
   

2. 确认中间件顺序正确性
   确保Program.cs中中间件顺序符合.NET认证规范，必须按以下顺序配置：

   app.UseRouting();
   app.UseAuthentication();
   app.UseAuthorization();
   app.MapBlazorHub(); // 必须在认证中间件之后注册
   app.MapFallbackToPage("/_Host");
   

3. 优化用户ID获取逻辑
   建议使用ClaimTypes.NameIdentifier作为用户唯一标识（而非ClaimTypes.Name），避免用户名重复导致的问题：

   public string? GetUserId(HubConnectionContext connection)
   {
       var userId = connection.User.FindFirstValue(ClaimTypes.NameIdentifier);
       return string.IsNullOrWhiteSpace(userId) ? string.Empty : userId;
   }
   

4. 复用HubConnection避免重复创建
   将HubConnection封装为注入服务，避免每次组件初始化都创建新连接：

   // 封装Hub服务类
   public class NotifyHubService
   {
       public HubConnection HubConnection { get; }
   
       public NotifyHubService(NavigationManager navigationManager)
       {
           HubConnection = new HubConnectionBuilder()
               .WithUrl(navigationManager.ToAbsoluteUri("/notifyhub"), options =>
               {
                   options.Credentials = FetchCredentials.Include;
               })
               .WithAutomaticReconnect()
               .Build();
       }
   }
   
   // Program.cs中注册服务
   builder.Services.AddScoped<NotifyHubService>();
   
   // 组件中注入使用
   [Inject]
   private NotifyHubService HubService { get; set; }
   
   protected override async Task OnInitializedAsync()
   {
       if (HubService.HubConnection.State == HubConnectionState.Disconnected)
       {
           await HubService.HubConnection.StartAsync();
       }
       HubService.HubConnection.On<int, string>("ReceiveMessage", (id, message) =>
       {
           var encodedMsg = $"{id}: {message}";
           InvokeAsync(StateHasChanged);
       });
   }
   

内容的提问来源于stack exchange，提问作者Dmidecode