From 24f444b9f7089a1045edcbac95efe77216a9a368 Mon Sep 17 00:00:00 2001
From: Thomas Eizinger <thomas@eizinger.io>
Date: Thu, 1 Apr 2021 16:38:33 +1100
Subject: [PATCH] Race sending transfer proof against cancel timelock

Sending the transfer proof might never resolve because Bob doesn't
come back online. In that case, we need to make sure we bail out
as soon as the timelock expires.
---
 swap/src/protocol/alice/swap.rs | 35 ++++++++++++++++++---------------
 1 file changed, 19 insertions(+), 16 deletions(-)

diff --git a/swap/src/protocol/alice/swap.rs b/swap/src/protocol/alice/swap.rs
index c7acbc66..2f2b1c86 100644
--- a/swap/src/protocol/alice/swap.rs
+++ b/swap/src/protocol/alice/swap.rs
@@ -116,29 +116,32 @@ async fn next_state(
                 state3,
             },
         },
-
         AliceState::XmrLocked {
             monero_wallet_restore_blockheight,
             transfer_proof,
             state3,
-        } => match state3.expired_timelocks(bitcoin_wallet).await? {
-            ExpiredTimelocks::None => {
-                event_loop_handle
-                    .send_transfer_proof(transfer_proof.clone())
-                    .await?;
+        } => {
+            let tx_lock_status = bitcoin_wallet.subscribe_to(state3.tx_lock.clone()).await;
 
-                XmrLockTransferProofSent {
-                    monero_wallet_restore_blockheight,
-                    transfer_proof,
-                    state3,
+            tokio::select! {
+                result = event_loop_handle.send_transfer_proof(transfer_proof.clone()) => {
+                   result?;
+
+                   XmrLockTransferProofSent {
+                       monero_wallet_restore_blockheight,
+                       transfer_proof,
+                       state3,
+                   }
+                },
+                _ = tx_lock_status.wait_until_confirmed_with(state3.cancel_timelock) => {
+                    AliceState::CancelTimelockExpired {
+                        monero_wallet_restore_blockheight,
+                        transfer_proof,
+                        state3,
+                    }
                 }
             }
-            _ => AliceState::CancelTimelockExpired {
-                monero_wallet_restore_blockheight,
-                transfer_proof,
-                state3,
-            },
-        },
+        }
         AliceState::XmrLockTransferProofSent {
             monero_wallet_restore_blockheight,
             transfer_proof,