Add project files.

src/common/Elsa.Api.Common/Requirements/LocalHostRequirement.cs

@@ -0,0 +1,36 @@
+using Elsa.Extensions;
+using JetBrains.Annotations;
+using Microsoft.AspNetCore.Authorization;
+using Microsoft.AspNetCore.Http;
+
+namespace Elsa.Requirements;
+
+/// <summary>
+/// Represents an authorization requirement for localhost requests, meaning that if a request comes from the localhost, the requirement is met.
+/// </summary>
+public class LocalHostRequirement : IAuthorizationRequirement
+{
+}
+
+/// <inheritdoc />
+[PublicAPI]
+public class LocalHostRequirementHandler : AuthorizationHandler<LocalHostRequirement>
+{
+    private readonly IHttpContextAccessor _httpContextAccessor;
+
+    /// <inheritdoc />
+    public LocalHostRequirementHandler(IHttpContextAccessor httpContextAccessor)
+    {
+        _httpContextAccessor = httpContextAccessor;
+    }
+
+    /// <inheritdoc />
+    protected override Task HandleRequirementAsync(AuthorizationHandlerContext context, LocalHostRequirement requirement)
+    {
+        if (_httpContextAccessor.HttpContext?.Request.IsLocal() == false)
+            context.Fail(new AuthorizationFailureReason(this, "Only requests from localhost are allowed"));
+
+        context.Succeed(requirement);
+        return Task.CompletedTask;
+    }
+}