Скачать или смотреть Solving Forbidden Errors with Custom Middleware in .Net Core

Learn how to effectively handle `Forbidden` errors in your .Net Core custom middleware, guiding users to the right error controller without causing infinite redirects.
---
This video is based on the question https://stackoverflow.com/q/74656143/ asked by the user 'Rajeev Menon' ( https://stackoverflow.com/u/1240358/ ) and on the answer https://stackoverflow.com/a/74659930/ provided by the user 'Rajeev Menon' ( https://stackoverflow.com/u/1240358/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: .Net core custom middleware - How to come out with Forbidden error and goto Error controller

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l...
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Handling Forbidden Errors with Custom Middleware in .Net Core

When developing applications using .Net Core, you may run into situations where you need a robust way to handle authentication and authorization scenarios. Sometimes, you need a custom middleware layer to enforce additional checks that aren’t covered by standard authentication and authorization methods. However, what happens when you encounter Forbidden errors? In this guide, we will explore how to properly handle such errors in your custom middleware and redirect users to the error controller efficiently without falling into endless redirect loops.

The Problem: Navigating Forbidden Errors

In certain cases, your custom middleware logic might set the response status code to 403, indicating that access is forbidden. A common challenge developers face here is to ensure that after setting this forbidden status code, the request stops processing further down the middleware pipeline. Failing to do so can lead to unexpected behavior, like accumulating responses that should not be combined or, in some cases, infinite redirects when utilizing response.Redirect() for error pages.

Common Scenarios Leading to Forbidden Errors

Custom Authentication Failures: When users do not meet the authentication criteria.

Authorization Issues: Users may authenticate successfully but fail authorization checks.

Business Logic Restrictions: Certain application rules may deny access based on specific conditions.

The Solution: Properly Handling Middleware Flow

Below is a step-by-step guide to ensure your custom middleware handles Forbidden responses correctly and navigates the user to the designated error controller effectively.

Step 1: Setting the Status Code

To trigger a 403 Forbidden response, start by setting the response status code in your middleware as shown below:

[[See Video to Reveal this Text or Code Snippet]]

Step 2: Complete the Response

Instead of calling the next middleware in the pipeline, which could interfere with your intended logic and allow further processing, you need to complete the response. By using:

[[See Video to Reveal this Text or Code Snippet]]

This method stops any further handling of the request immediately after sending the Forbidden status.

Step 3: Bypassing the Next Middleware

To match this with the .Net Core middleware pattern, remove or comment out the call to _next(context). By skipping this call, you effectively prevent subsequent middleware from executing, ensuring that only your error handling code runs.

Final Code Example

Here’s the implementation reflecting the suggested solution:

[[See Video to Reveal this Text or Code Snippet]]

Notes on Implementation

Ensure that the Error controller and related views are set up properly to handle these 403 Forbidden responses.

Test your middleware thoroughly, particularly scenarios where the custom checks could diverge from standard authorization.

Conclusion

Navigating Forbidden errors in custom middleware within a .Net Core application does not have to be complicated. By following the outlined steps—setting the status code, completing the response, and carefully controlling the middleware pipeline—you can effectively redirect users to the appropriate error handling logic without falling into potential pitfalls like infinite redirect loops. Implementing these practices will help enhance the user experience in your applications, making them more robust and reliable.

If you have found this guide helpful, feel free to share it with other developers facing similar challenges in their .Net Core projects!