Building an authentication gateway for external API in ASP.NET Core

Other Questions API
1

I’m working on an ASP.NET Core app that needs to act as a middleman between clients and an external API. Here’s what I want to do:

  1. Give clients a special token when they ask for it
  2. Check if the client’s request has a valid token
  3. If it does, forward the request to the external API using Basic auth
  4. Send the API’s response back to the client

I’ve got some code that seems to work, but I’m not sure if it’s the best way to do this. Here’s a simplified version:

[HttpGet]
public async Task ForwardGet()
{
    // TODO: Check token

    var apiResponse = await _apiClient.GetAsync(Request.QueryString.Value);
    await CopyResponseToClient(apiResponse);
}

[HttpPost]
public async Task ForwardPost()
{
    // TODO: Check token

    var apiResponse = await _apiClient.PostAsync(string.Empty, new StreamContent(Request.Body));
    await CopyResponseToClient(apiResponse);
}

private async Task CopyResponseToClient(HttpResponseMessage apiResponse)
{
    Response.StatusCode = (int)apiResponse.StatusCode;
    Response.ContentType = apiResponse.Content.Headers.ContentType?.ToString();
    Response.ContentLength = apiResponse.Content.Headers.ContentLength;
    await Response.WriteAsync(await apiResponse.Content.ReadAsStringAsync());
}

Is this a good approach? Will it cause issues if the application scales up? Also, is there a simpler method for managing token creation and validation?

2

hey, ur approach looks ok but there’s room for improvement. have u considered using JWT for token stuff? it’s pretty solid. also, maybe think bout using a cache like Redis if u need to scale up. oh, and be careful with big responses - streaming might be better than loading everything into memory. don’t forget to handle errors properly too!

3

I’ve implemented a similar authentication gateway in one of my projects, and I can share some insights from that experience.

Your approach is on the right track, but there are a few improvements you could make. For token management, I’d recommend using JWT (JSON Web Tokens). They’re secure, can carry claims, and are widely supported.

For scalability, consider using a distributed cache like Redis for token storage. This will help if you need to scale horizontally.

One thing to watch out for is memory usage when forwarding large payloads. Instead of reading the entire response into memory, you might want to stream it directly to the client.

Also, don’t forget to handle errors gracefully, both from the external API and from token validation. You don’t want to expose sensitive information in error messages.

Lastly, for simplicity, you could look into using a library like IdentityServer4 for token management. It can handle a lot of the complexities for you.

4

Your approach seems solid, but there are a few considerations to keep in mind. For token management, I’d suggest using a library like IdentityServer or implementing JWT tokens. They’re secure and widely supported in the .NET ecosystem.

For scalability, you might want to look into caching strategies, especially if you’re dealing with high traffic. Redis could be a good option here.

One potential issue I see is with large payloads. Instead of reading the entire response into memory, consider streaming it to the client. This can significantly reduce memory usage.

Also, don’t forget to implement proper error handling and logging. It’s crucial for debugging and maintaining the system in production.

Lastly, you might want to consider rate limiting to protect both your service and the external API from potential abuse or overload.