Oidc.Auth 1.0.2

Oidc.Auth

A lightweight, reusable OIDC (OpenID Connect) authentication helper for .NET 8 ASP.NET Core applications.

• Build authorization redirect URLs with a secure random nonce
• Exchange authorization codes for tokens via a typed HttpClient
• Zero boilerplate: register with a single AddOidcAuth(...) call
• Fully configurable via the options pattern or appsettings.json

Installation

dotnet add package Oidc.Auth

Quick Start

Option 1 — Inline options (environment variables, secrets manager, etc.)

// Program.cs
using Oidc.Auth.Extensions;

builder.Services.AddOidcAuth(options =>
{
    options.AuthorizationEndpoint = Environment.GetEnvironmentVariable("OAUTH_URL")!;
    options.TokenEndpoint         = Environment.GetEnvironmentVariable("OTOKEN_URL")!;
    options.ClientId              = Environment.GetEnvironmentVariable("OAUTH_CLIENT_ID")!;
    options.ClientSecret          = Environment.GetEnvironmentVariable("OAUTH_CLIENT_SECRET")!;
    options.Scope                 = "openid profile email"; // default: "openid"
});

Option 2 — appsettings.json

// appsettings.json
{
  "OidcAuth": {
    "AuthorizationEndpoint": "https://your-idp.example.com/auth",
    "TokenEndpoint":         "https://your-idp.example.com/token",
    "ClientId":              "your-client-id",
    "ClientSecret":          "your-client-secret",
    "Scope":                 "openid profile email"
  }
}

// Program.cs
builder.Services.AddOidcAuth(builder.Configuration);
// or with a custom section name:
builder.Services.AddOidcAuth(builder.Configuration, sectionName: "MyOidcSection");

Usage

Inject IOidcAuthService into your controller or service:

using Oidc.Auth.Abstractions;
using Microsoft.AspNetCore.Mvc;

[ApiController]
[Route("auth")]
public class AuthController(IOidcAuthService oidcAuth) : ControllerBase
{
    [HttpGet("login")]
    public IActionResult Login([FromQuery] string redirect_uri)
    {
        var url = oidcAuth.BuildAuthorizationUrl(redirect_uri);
        return Ok(new { url });
    }

    [HttpGet("callback")]
    public async Task<IActionResult> Callback([FromQuery] string code, [FromQuery] string redirect_uri)
    {
        var tokenResponse = await oidcAuth.ExchangeCodeForTokenAsync(code, redirect_uri);
        return Ok(tokenResponse);
    }
}

Configuration Reference

Error Handling

ExchangeCodeForTokenAsync throws OidcAuthException on:

• Non-2xx responses from the token endpoint (includes status code + body in message)
• Network/IO errors (wrapped with the original exception as inner)

using Oidc.Auth.Exceptions;

try
{
    var token = await oidcAuth.ExchangeCodeForTokenAsync(code, redirectUri);
}
catch (OidcAuthException ex)
{
    // handle token exchange failure
}

License

MIT