Timeout for Alice waiting for ack for sending transfer proof

If dialing Bob fails Alice waits for the acknowledgement of the transfer proof indefinitely.
The timout prevents her execution from hanging.
Added a ToDo to re-visit the ack receivers. They don't add value at the moment and should be removed.

swap/src/protocol/alice/event_loop.rs

@@ -1,4 +1,5 @@
 use crate::{
+    execution_params::ExecutionParams,
     network::{transport::SwapTransport, TokioExecutor},
     protocol::{
         alice::{Behaviour, OutEvent, State0, State3, SwapResponse, TransferProof},
@@ -9,7 +10,10 @@ use anyhow::{anyhow, Context, Result};
 use libp2p::{
     core::Multiaddr, futures::FutureExt, request_response::ResponseChannel, PeerId, Swarm,
 };
-use tokio::sync::mpsc::{Receiver, Sender};
+use tokio::{
+    sync::mpsc::{Receiver, Sender},
+    time::timeout,
+};
 use tracing::{error, trace};
 
 #[allow(missing_debug_implementations)]
@@ -91,13 +95,27 @@ impl EventLoopHandle {
         Ok(())
     }
 
-    pub async fn send_transfer_proof(&mut self, bob: PeerId, msg: TransferProof) -> Result<()> {
+    pub async fn send_transfer_proof(
+        &mut self,
+        bob: PeerId,
+        msg: TransferProof,
+        execution_params: ExecutionParams,
+    ) -> Result<()> {
         let _ = self.send_transfer_proof.send((bob, msg)).await?;
 
-        self.recv_transfer_proof_ack
-            .recv()
-            .await
-            .ok_or_else(|| anyhow!("Failed to receive transfer proof ack from Bob"))?;
+        // TODO: Re-evaluate if these acknowledges are necessary at all.
+        // If we don't use a timeout here and Alice fails to dial Bob she will wait
+        // indefinitely for this acknowledge.
+        if timeout(
+            execution_params.bob_time_to_act,
+            self.recv_transfer_proof_ack.recv(),
+        )
+        .await
+        .is_err()
+        {
+            error!("Failed to receive transfer proof ack from Bob")
+        }
+
         Ok(())
     }
 }

swap/src/protocol/alice/steps.rs

@@ -96,6 +96,7 @@ pub async fn lock_xmr<W>(
     state3: alice::State3,
     event_loop_handle: &mut EventLoopHandle,
     monero_wallet: Arc<W>,
+    execution_params: ExecutionParams,
 ) -> Result<()>
 where
     W: Transfer,
@@ -117,9 +118,13 @@ where
     //  Otherwise Alice might publish the lock tx twice!
 
     event_loop_handle
-        .send_transfer_proof(bob_peer_id, TransferProof {
-            tx_lock_proof: transfer_proof,
-        })
+        .send_transfer_proof(
+            bob_peer_id,
+            TransferProof {
+                tx_lock_proof: transfer_proof,
+            },
+            execution_params,
+        )
         .await?;
 
     Ok(())

swap/src/protocol/alice/swap.rs

@@ -165,6 +165,7 @@ async fn run_until_internal(
                     *state3.clone(),
                     &mut event_loop_handle,
                     monero_wallet.clone(),
+                    execution_params,
                 )
                 .await?;
 

swap/tests/bob_refunds_using_cancel_and_refund_command.rs

@@ -10,7 +10,7 @@ async fn given_bob_manually_refunds_after_btc_locked_bob_refunds() {
         let (bob_swap, bob_join_handle) = ctx.new_swap_as_bob().await;
 
         let alice_handle = alice::run(alice_swap);
-        tokio::spawn(alice_handle);
+        let alice_swap_handle = tokio::spawn(alice_handle);
 
         let bob_state = bob::run_until(bob_swap, is_btc_locked).await.unwrap();
 
@@ -57,10 +57,8 @@ async fn given_bob_manually_refunds_after_btc_locked_bob_refunds() {
 
         ctx.assert_bob_refunded(bob_state).await;
 
-        // TODO: Alice hangs indefinitely waiting for Blob's acknowledge on
-        //  sending the transfer proof
-        // let alice_state = alice_swap_handle.await.unwrap().unwrap();
-        // ctx.assert_alice_refunded(alice_state).await;
+        let alice_state = alice_swap_handle.await.unwrap().unwrap();
+        ctx.assert_alice_refunded(alice_state).await;
     })
     .await;
 }