From 0933943dd67b8b2f28b48341f4e6b2188bf5062d Mon Sep 17 00:00:00 2001
From: Jason Volk <jason@zemos.net>
Date: Thu, 26 Feb 2026 13:06:36 +0000
Subject: [PATCH] Remove bad_event_ratelimiter entries after expiration.

Signed-off-by: Jason Volk <jason@zemos.net>
---
 src/service/rooms/event_handler/fetch_auth.rs |  9 +++++++--
 .../event_handler/handle_incoming_pdu.rs      |  3 +++
 src/service/rooms/event_handler/mod.rs        | 19 +++++++++++++++++--
 3 files changed, 27 insertions(+), 4 deletions(-)

diff --git a/src/service/rooms/event_handler/fetch_auth.rs b/src/service/rooms/event_handler/fetch_auth.rs
index 298f75f4..7a442e5a 100644
--- a/src/service/rooms/event_handler/fetch_auth.rs
+++ b/src/service/rooms/event_handler/fetch_auth.rs
@@ -4,7 +4,7 @@ use std::{
 	time::Duration,
 };
 
-use futures::{FutureExt, StreamExt};
+use futures::{FutureExt, StreamExt, TryFutureExt};
 use ruma::{
 	CanonicalJsonObject, CanonicalJsonValue, EventId, OwnedEventId, RoomId, RoomVersionId,
 	ServerName, api::federation::event::get_event,
@@ -89,6 +89,7 @@ where
 						if next_id == id {
 							pdus.push((pdu, Some(json)));
 						}
+						self.cancel_back_off(&next_id);
 					} else {
 						self.back_off(&next_id);
 					}
@@ -152,8 +153,11 @@ async fn fetch_auth_chain(
 			.services
 			.federation
 			.execute(origin, get_event::v1::Request { event_id: next_id.clone() })
+			.inspect_err(|e| debug_error!(?next_id, "Failed to fetch event: {e}"))
+			.inspect_ok(|_| {
+				self.cancel_back_off(&next_id);
+			})
 			.await
-			.inspect_err(|e| debug_error!("Failed to fetch event {next_id}: {e}"))
 		else {
 			debug_warn!("Backing off from {next_id}");
 			self.back_off(&next_id);
@@ -168,6 +172,7 @@ async fn fetch_auth_chain(
 			continue;
 		};
 
+		self.cancel_back_off(&next_id);
 		if calculated_event_id != next_id {
 			warn!(
 				"Server didn't return event id we requested: requested: {next_id}, we got \
diff --git a/src/service/rooms/event_handler/handle_incoming_pdu.rs b/src/service/rooms/event_handler/handle_incoming_pdu.rs
index a1fcf6bb..99cc930a 100644
--- a/src/service/rooms/event_handler/handle_incoming_pdu.rs
+++ b/src/service/rooms/event_handler/handle_incoming_pdu.rs
@@ -170,6 +170,9 @@ pub async fn handle_incoming_pdu<'a>(
 				warn!("Prev {prev_id} failed: {e}");
 				self.back_off(prev_id);
 			})
+			.inspect_ok(|()| {
+				self.cancel_back_off(prev_id);
+			})
 			.map(|_| self.services.server.check_running())
 		})
 		.boxed()
diff --git a/src/service/rooms/event_handler/mod.rs b/src/service/rooms/event_handler/mod.rs
index b34300b7..ae77eae5 100644
--- a/src/service/rooms/event_handler/mod.rs
+++ b/src/service/rooms/event_handler/mod.rs
@@ -76,7 +76,16 @@ impl crate::Service for Service {
 }
 
 #[implement(Service)]
-fn back_off(&self, event_id: &EventId) {
+fn cancel_back_off(&self, event_id: &EventId) -> bool {
+	self.bad_event_ratelimiter
+		.write()
+		.expect("locked")
+		.remove(event_id)
+		.is_some()
+}
+
+#[implement(Service)]
+fn back_off(&self, event_id: &EventId) -> bool {
 	use hash_map::Entry::{Occupied, Vacant};
 
 	match self
@@ -87,9 +96,11 @@ fn back_off(&self, event_id: &EventId) {
 	{
 		| Vacant(e) => {
 			e.insert((Instant::now(), 1));
+			true
 		},
 		| Occupied(mut e) => {
 			*e.get_mut() = (Instant::now(), e.get().1.saturating_add(1));
+			false
 		},
 	}
 }
@@ -106,7 +117,11 @@ fn is_backed_off(&self, event_id: &EventId, range: Range<Duration>) -> bool {
 		return false;
 	};
 
-	continue_exponential_backoff(range.start, range.end, time.elapsed(), tries)
+	if !continue_exponential_backoff(range.start, range.end, time.elapsed(), tries) {
+		return false;
+	}
+
+	true
 }
 
 #[implement(Service)]