BasicAuthentication als Attribut für Actions

AMWD.Common.AspNetCore/BasicAuthentication/BasicAuthenticationMiddleware.cs

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+using System;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using Microsoft.AspNetCore.Http;
+
+namespace AMWD.Common.AspNetCore.BasicAuthentication
+{
+	/// <summary>
+	/// Implements a basic authentication.
+	/// </summary>
+	public class BasicAuthenticationMiddleware
+	{
+		private readonly RequestDelegate next;
+		private readonly string realm;
+		private readonly IBasicAuthenticationValidator validator;
+
+		/// <summary>
+		/// Initializes a new instance of the <see cref="BasicAuthenticationMiddleware"/> class.
+		/// </summary>
+		/// <param name="next">The following delegate in the process chain.</param>
+		/// <param name="realm">The realm to display when requesting for credentials.</param>
+		/// <param name="validator">A basic authentication validator.</param>
+		public BasicAuthenticationMiddleware(RequestDelegate next, string realm, IBasicAuthenticationValidator validator)
+		{
+			this.next = next;
+			this.realm = realm;
+			this.validator = validator;
+		}
+
+		/// <summary>
+		/// The delegate invokation.
+		/// Performs the authentication check.
+		/// </summary>
+		/// <param name="httpContext">The corresponding HTTP context.</param>
+		/// <returns>An awaitable task.</returns>
+		public async Task InvokeAsync(HttpContext httpContext)
+		{
+			if (httpContext.Request.Headers.TryGetValue("Authorization", out var authHeader)
+				&& ((string)authHeader).StartsWith("Basic "))
+			{
+				string encoded = ((string)authHeader).Split(' ', StringSplitOptions.RemoveEmptyEntries).LastOrDefault() ?? "";
+
+				string decoded = Encoding.UTF8.GetString(Convert.FromBase64String(encoded));
+				string[] parts = decoded.Split(':', 2);
+
+				var principal = validator.ValidateAsync(parts[0], parts[1], httpContext.GetRemoteIpAddress());
+				if (principal != null)
+				{
+					await next.Invoke(httpContext);
+					return;
+				}
+			}
+
+			httpContext.Response.Headers["WWW-Authenticate"] = "Basic";
+			if (!string.IsNullOrWhiteSpace(realm))
+			{
+				httpContext.Response.Headers["WWW-Authenticate"] += $" realm=\"{realm}\"";
+			}
+
+			httpContext.Response.StatusCode = StatusCodes.Status401Unauthorized;
+		}
+	}
+}