Domain blocks: suspend, silence, reject media

DomainBlock (domain, severity, reject-media, public and private comment)
covers the domain and its subdomains. Admins manage them under
/clientapi/admin/domainblocks/{list,insert,delete}; the set is kept in
memory, reloaded on every change and at most five minutes stale.

A suspended domain is refused by FederationHttp.IsAllowed, so nothing is
fetched from it and no job delivers to it, and the inbox drops its
activities with a 202 before fetching any key. Reject-media strips the
attachments of posts from that domain. Silence is recorded for the
timelines and notifications that arrive in P1.2.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_012CzABvBkbcFqoHdmi8b9WB

PrivaPub.Tests/Federation/InboxScenarioTests.cs

@@ -4,16 +4,18 @@ using Microsoft.Extensions.Logging.Abstractions;
 using MongoDB.Entities;
 
 using PrivaPub.Federation.Actors;
-using PrivaPub.Federation.Inbox;
-using PrivaPub.Federation.Objects;
 using PrivaPub.Federation.Inbox.Handlers;
-using PrivaPub.Models.Jobs;
+using PrivaPub.Federation.Inbox;
+using PrivaPub.Federation.Moderation;
+using PrivaPub.Federation.Objects;
 using PrivaPub.Federation.Outbox;
 using PrivaPub.Infrastructure.Jobs;
-using PrivaPub.Models;
+using PrivaPub.Models.Federation;
 using PrivaPub.Models.Group;
+using PrivaPub.Models.Jobs;
 using PrivaPub.Models.Post;
 using PrivaPub.Models.User;
+using PrivaPub.Models;
 using PrivaPub.StaticServices;
 using PrivaPub.Tests.Support;
 
@@ -33,6 +35,7 @@ namespace PrivaPub.Tests.Federation
 		LocalActorService _local;
 		InboxReceiver _receiver;
 		InboxProcessor _processor;
+		DomainBlocks _blocks;
 
 		public async ValueTask InitializeAsync()
 		{
@@ -44,12 +47,13 @@ namespace PrivaPub.Tests.Federation
 			var queue = new JobQueue();
 			var delivery = new DeliveryService(new DbEntities(), queue);
 			var db = new DbEntities();
-			_receiver = new InboxReceiver(_local, remote, queue, NullLogger<InboxReceiver>.Instance);
+			_blocks = new DomainBlocks(NullLogger<DomainBlocks>.Instance);
+			_receiver = new InboxReceiver(_local, remote, queue, _blocks, NullLogger<InboxReceiver>.Instance);
 			_processor = new InboxProcessor(remote, new IActivityHandler[]
 			{
 				new FollowHandler(db, _local, remote, delivery),
 				new UndoHandler(db, _local, remote, delivery),
-				new CreateHandler(db, _local, remote, delivery),
+				new CreateHandler(db, _local, remote, delivery, _blocks),
 				new DeleteHandler(db, _local, remote, delivery),
 				new UpdateHandler(db, _local, remote)
 			}, NullLogger<InboxProcessor>.Instance);
@@ -254,6 +258,46 @@ namespace PrivaPub.Tests.Federation
 			Assert.Equal(alice.Id, mention.AccountId);
 		}
 
+		[Fact]
+		public async Task A_suspended_domain_is_dropped_before_its_key_is_fetched()
+		{
+			var token = TestContext.Current.CancellationToken;
+			var alice = await LocalAvatar("alice");
+			var bob = new RemoteActor(_peer, "bob", _peer.B);
+			await DB.Default.SaveAsync(new DomainBlock { Domain = "localhost", Severity = DomainBlockSeverity.Suspend }, token);
+			try
+			{
+				await _blocks.Reload(token);
+				var before = _peer.Requests.Count;
+
+				var result = await Deliver(bob, $"/peasants/{alice.UserName}/mouth", DirectCreate(bob, alice.Uri));
+
+				Assert.Equal(202, result.StatusCode);
+				Assert.Equal(before, _peer.Requests.Count);
+				Assert.False(await DB.Default.Find<Post>().Match(p => p.ActorURI == bob.Id).ExecuteAnyAsync(token));
+			}
+			finally
+			{
+				await DB.Default.DeleteAsync<DomainBlock>(b => b.Domain == "localhost");
+				await _blocks.Reload(token);
+			}
+		}
+
+		[Fact]
+		public void A_block_covers_subdomains_but_not_lookalikes()
+		{
+			var blocks = new DomainBlocks(NullLogger<DomainBlocks>.Instance);
+			typeof(DomainBlocks).GetField("_blocks", System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Instance)!
+				.SetValue(blocks, new Dictionary<string, DomainBlock> { ["evil.example"] = new() { Domain = "evil.example", Severity = DomainBlockSeverity.Silence } });
+			typeof(DomainBlocks).GetField("_loadedAt", System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Instance)!
+				.SetValue(blocks, DateTime.UtcNow);
+
+			Assert.NotNull(blocks.Find("evil.example"));
+			Assert.NotNull(blocks.Find("A.Evil.Example."));
+			Assert.Null(blocks.Find("notevil.example"));
+			Assert.False(blocks.IsSuspended("evil.example"));
+		}
+
 		[Fact]
 		public async Task A_bad_signature_is_a_401()
 		{