Rate Policy

Libraries/Esiur/Security/RateLimiting/RatePolicy.cs

@@ -0,0 +1,72 @@
+using Esiur.Data.Types;
+using Esiur.Protocol;
+using Esiur.Resource;
+using Esiur.Security.Authority;
+using Esiur.Security.Permissions;
+using System;
+
+namespace Esiur.Security.RateLimiting;
+
+/// <summary>
+/// Describes the request currently being evaluated by a rate policy.
+/// </summary>
+public sealed class RateControlContext
+{
+    public Warehouse Warehouse { get; }
+    public EpConnection Connection { get; }
+    public Session Session { get; }
+    public IResource? Resource { get; }
+    public MemberDef Member { get; }
+    public ActionType Action { get; }
+
+    /// <summary>
+    /// Optional delay assigned by a policy to an allowed queued request.
+    /// </summary>
+    public TimeSpan Delay { get; set; }
+
+    public RateControlContext(
+        Warehouse warehouse,
+        EpConnection connection,
+        Session session,
+        IResource? resource,
+        MemberDef member,
+        ActionType action)
+    {
+        Warehouse = warehouse ?? throw new ArgumentNullException(nameof(warehouse));
+        Connection = connection ?? throw new ArgumentNullException(nameof(connection));
+        Session = session ?? throw new ArgumentNullException(nameof(session));
+        Resource = resource;
+        Member = member ?? throw new ArgumentNullException(nameof(member));
+        Action = action;
+    }
+}
+
+/// <summary>
+/// Base class for named Warehouse rate-control policies.
+/// </summary>
+public abstract class RatePolicy
+{
+    /// <summary>
+    /// Name referenced by <see cref="RateControlAttribute"/>.
+    /// </summary>
+    public string Name { get; set; } = string.Empty;
+
+    protected RatePolicy()
+    {
+    }
+
+    protected RatePolicy(string name)
+    {
+        Name = name;
+    }
+
+    /// <summary>
+    /// Evaluates a context-free policy. Override this for simple policies.
+    /// </summary>
+    public virtual Ruling Applicable() => Ruling.DontCare;
+
+    /// <summary>
+    /// Evaluates a request. Context-aware policies should override this overload.
+    /// </summary>
+    public virtual Ruling Applicable(RateControlContext context) => Applicable();
+}