ASP.NET Core 6微服务中RabbitMQ RPC获取登录用户名失败问题

我有两个微服务：

• 负责授权认证的Identity Service（运行在localhost:7096，基于Identity系统配置）
• 为已认证用户提供资源的Application Service（运行在localhost:7141）

当通过RabbitMQ RPC模式从Identity Service获取已登录用户的用户名时出现异常：

• Identity Service提供get-logged-in-user-name端点，通过自定义扩展方法ClaimPrincipleExtension.GetUsername获取当前登录用户的用户名
• 直接调用该端点功能正常，但通过Application Service的RabbitMQ消费者发起HTTP请求调用时抛出异常
• 若在端点中返回硬编码字符串（如"ExampleUser"）则一切正常

相关代码 #

RabbitMQ消费者代码 #

private async void ConsumerReceived(object sender, BasicDeliverEventArgs e)
{
        var response = "";

        var body = e.Body.ToArray();
        var props = e.BasicProperties;
        var replyProps = _channel.CreateBasicProperties();
        replyProps.CorrelationId = props.CorrelationId;

        try
        {
            var wee = _serviceProvider.GetService<IHttpClientFactory>();

            var client = wee.CreateClient();

            var loggedUserName = await client.GetAsync("https://localhost:7096/get-logged-in-user-name");

            response = await loggedUserName.Content.ReadAsStringAsync();
        }
        catch (Exception E)
        {
            Console.WriteLine(E);
            response = "null";
        }
        finally
        {
            var responseBytes = Encoding.UTF8.GetBytes(response);
            _channel.BasicPublish(exchange: "",
                routingKey: props.ReplyTo,
                basicProperties: replyProps,
                body: responseBytes);

            _channel.BasicAck(deliveryTag: e.DeliveryTag,
                multiple: false);
        }
}

扩展方法代码 #

public static class ClaimPrincipleExtension
{
    public static string GetUsername(this ClaimsPrincipal user)
    {
        return user.FindFirst(ClaimTypes.Name).Value;
    }
}

端点代码 #

[HttpGet("get-logged-in-user-name")]
public string GetLoggedInUserName()
{
        string username = User.GetUsername(); //!< -获取当前登录用户名
        return username; //!< -在此处触发RPC服务端与客户端错误
        // return "ExampleUser"; //! <-返回该硬编码值则一切正常
}

错误堆栈信息 #

at Shared.Abstraction.Extensions.ClaimPrincipleExtension.GetUsername(ClaimsPrincipal user) in /Users/michal/Desktop/MyDateApp/Shared/Extensions/ClaimPrincipleExtension.cs:line 10
at IdentityServer.Application.Controllers.UserController.GetLoggedInUserName() in /Users/michal/Desktop/MyDateApp/MicroServices/IdentityServer/IdentityServer.Application/Controllers/UserController.cs:line 41
at lambda_method3(Closure , Object , Object[] )
at Microsoft.AspNetCore.Mvc.Infrastructure.ActionMethodExecutor.SyncObjectResultExecutor.Execute(IActionResultTypeMapper mapper, ObjectMethodExecutor executor, Object controller, Object[] arguments)
at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.InvokeActionMethodAsync()
at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.InvokeNextActionFilterAsync()
--- End of stack trace from previous location ---
at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.Rethrow(ActionExecutedContextSealed context)
at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.InvokeInnerFilterAsync()
--- End of stack trace from previous location ---
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.g__Awaited|25_0(ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Rethrow(ResourceExecutedContextSealed context)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.InvokeFilterPipelineAsync()
--- End of stack trace from previous location ---
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.g__Awaited|17_0(ResourceInvoker invoker, Task task, IDisposable scope)
at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.g__Awaited|17_0(ResourceInvoker invoker, Task task, IDisposable scope)
at Microsoft.AspNetCore.Routing.EndpointMiddleware.g__AwaitRequestTask|6_0(Endpoint endpoint, Task requestTask, ILogger logger)
at Microsoft.AspNetCore.Authorization.AuthorizationMiddleware.Invoke(HttpContext context)
at Microsoft.AspNetCore.Authentication.AuthenticationMiddleware.Invoke(HttpContext context)
at Swashbuckle.AspNetCore.SwaggerUI.SwaggerUIMiddleware.Invoke(HttpContext httpContext)
at Microsoft.AspNetCore.Session.SessionMiddleware.Invoke(HttpContext context)
at Microsoft.AspNetCore.Session.SessionMiddleware.Invoke(HttpContext context)
at Swashbuckle.AspNetCore.Swagger.SwaggerMiddleware.Invoke(HttpContext httpContext, ISwaggerProvider swaggerProvider)
at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.Invoke(HttpContext context)

请求头 #

Host: localhost:7096

问题分析与解决方案 #

核心原因 #

从错误堆栈可知，异常发生在ClaimPrincipleExtension.GetUsername方法第10行：user.FindFirst(ClaimTypes.Name)返回null，访问.Value时触发空引用异常。

直接调用端点正常，是因为浏览器/客户端请求携带了认证令牌（如JWT Cookie或Authorization头），Identity Service能识别用户并填充ClaimsPrincipal；而RabbitMQ消费者发起的HTTP请求未携带任何认证信息，Identity Service无法识别用户，User对象不存在ClaimTypes.Name声明。

解决方案 #

1. 在HTTP请求中携带认证令牌
   当Application Service发送RabbitMQ RPC请求时，需将用户的认证令牌（如原始请求中的JWT）作为消息体传递给消费者。消费者拿到令牌后，在发起HTTP请求时添加Authorization头：

   // 从RabbitMQ消息体解析用户JWT令牌
   var token = Encoding.UTF8.GetString(body);
   client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", token);
   var loggedUserName = await client.GetAsync("https://localhost:7096/get-logged-in-user-name");
   

2. 优化扩展方法，添加空值检查
   修改ClaimPrincipleExtension.GetUsername方法，避免空引用异常，同时给出明确错误提示：

   public static class ClaimPrincipleExtension
   {
       public static string GetUsername(this ClaimsPrincipal user)
       {
           var nameClaim = user.FindFirst(ClaimTypes.Name);
           if (nameClaim == null)
           {
               throw new InvalidOperationException("当前用户未包含用户名声明");
               // 或返回默认值：return string.Empty;
           }
           return nameClaim.Value;
       }
   }
   

3. 为端点添加授权策略
   确保get-logged-in-user-name端点添加授权特性，未认证请求直接返回401，避免走到获取用户名的逻辑：

   [HttpGet("get-logged-in-user-name")]
   [Authorize] // 添加授权特性
   public string GetLoggedInUserName()
   {
       string username = User.GetUsername();
       return username;
   }
   

内容的提问来源于stack exchange，提问作者Micheal841