From 3d9f02f342a4c3d5e945e0e181c6efee08d53efa Mon Sep 17 00:00:00 2001
From: Farhad Shabani <farhad.shabani@gmail.com>
Date: Wed, 24 Jul 2024 08:18:14 -0700
Subject: [PATCH] fix: expire client when elapsed time from trusted equals
 trusting period

---
 .../1239-consider-client-expired-at-trusting-period.md       | 3 +++
 ibc-clients/ics07-tendermint/src/client_state/validation.rs  | 5 ++++-
 tests-integration/tests/core/ics02_client/update_client.rs   | 2 +-
 3 files changed, 8 insertions(+), 2 deletions(-)
 create mode 100644 .changelog/unreleased/bug-fixes/1239-consider-client-expired-at-trusting-period.md

diff --git a/.changelog/unreleased/bug-fixes/1239-consider-client-expired-at-trusting-period.md b/.changelog/unreleased/bug-fixes/1239-consider-client-expired-at-trusting-period.md
new file mode 100644
index 000000000..3f2ecbcd2
--- /dev/null
+++ b/.changelog/unreleased/bug-fixes/1239-consider-client-expired-at-trusting-period.md
@@ -0,0 +1,3 @@
+- [ibc-client-tendermint] Expire a client when the elapsed time from a trusted
+  header equals the trusting period, to stay consistent with the expiry logic in
+  `tendermint-rs` ([\#1239](https://github.com/cosmos/ibc-rs/issues/1239))
diff --git a/ibc-clients/ics07-tendermint/src/client_state/validation.rs b/ibc-clients/ics07-tendermint/src/client_state/validation.rs
index 116b84dd8..1e34fd770 100644
--- a/ibc-clients/ics07-tendermint/src/client_state/validation.rs
+++ b/ibc-clients/ics07-tendermint/src/client_state/validation.rs
@@ -221,7 +221,10 @@ where
     if let Some(elapsed_since_latest_consensus_state) =
         now.duration_since(&latest_consensus_state.timestamp().into())
     {
-        if elapsed_since_latest_consensus_state > client_state.trusting_period {
+        // Note: The equality is considered as expired to stay consistent with
+        // the check in tendermint-rs, where a header at `trusted_header_time +
+        // trusting_period` is considered as expired.
+        if elapsed_since_latest_consensus_state >= client_state.trusting_period {
             return Ok(Status::Expired);
         }
     }
diff --git a/tests-integration/tests/core/ics02_client/update_client.rs b/tests-integration/tests/core/ics02_client/update_client.rs
index d5f19f8eb..3cd5e96b5 100644
--- a/tests-integration/tests/core/ics02_client/update_client.rs
+++ b/tests-integration/tests/core/ics02_client/update_client.rs
@@ -1431,7 +1431,7 @@ fn test_expired_client() {
         );
 
     while ctx.ibc_store.host_timestamp().expect("no error")
-        < (timestamp + trusting_period).expect("no error")
+        <= (timestamp + trusting_period).expect("no error")
     {
         ctx.advance_block_height();
     }