From 69b2069dea160faff6b2b13bb3d660037f12649d Mon Sep 17 00:00:00 2001
From: Till <2353100+S7evinK@users.noreply.github.com>
Date: Sat, 8 Jul 2023 11:45:44 +0200
Subject: [PATCH] Avoid loops by setting end to an empty string if start == end
 (#3146)

---
 syncapi/routing/messages.go | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/syncapi/routing/messages.go b/syncapi/routing/messages.go
index 937e20ad8d..c38716185e 100644
--- a/syncapi/routing/messages.go
+++ b/syncapi/routing/messages.go
@@ -250,6 +250,12 @@ func OnIncomingMessagesRequest(
 		}
 	}
 
+	// If start and end are equal, we either reached the beginning or something else
+	// is wrong. To avoid endless loops from clients, set end to 0 an empty string
+	if start == end {
+		end = types.TopologyToken{}
+	}
+
 	util.GetLogger(req.Context()).WithFields(logrus.Fields{
 		"from":         from.String(),
 		"to":           to.String(),