Merge #705

705: Handle Results of waiting for timelocks to expire r=rishflab a=da-kami

Fixes an issue where the CLI is transitioning into a `CancelTimelockExpired` state but the timelock is actually not expired yet. 
This happened because watching for confirmations errored and the error was not handled but the same behaviour as reaching the cancel timelock height was applied.

For now this PR will fail the execution in case of the block height watching logic failing. Eventually there should be a more resilient strategy that includes retries. 

Co-authored-by: Daniel Karzel <daniel@comit.network>
Co-authored-by: rishflab <rishflab@hotmail.com>

CHANGELOG.md

@@ -16,6 +16,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - An issue where the ASB was unable to use the Monero wallet in case `monero-wallet-rpc` has been restarted.
   In case no wallet is loaded when we try to interact with the `monero-wallet-rpc` daemon, we now load the correct wallet on-demand.
   See issue https://github.com/comit-network/xmr-btc-swap/issues/652.
+- An issue where swap protocol was getting stuck trying to submit the cancel transaction.
+  We were not handling the error when TxCancel submission fails.
+  We also configured the electrum client to retry 5 times in order to help with this problem.
+  See issues: https://github.com/comit-network/xmr-btc-swap/issues/709 https://github.com/comit-network/xmr-btc-swap/issues/688, https://github.com/comit-network/xmr-btc-swap/issues/701.
 
 ## [0.8.1] - 2021-08-16
 

swap/src/bitcoin/wallet.rs

@@ -48,7 +48,10 @@ impl Wallet {
         env_config: env::Config,
         target_block: usize,
     ) -> Result<Self> {
-        let client = bdk::electrum_client::Client::new(electrum_rpc_url.as_str())
+        let config = bdk::electrum_client::ConfigBuilder::default()
+            .retry(5)
+            .build();
+        let client = bdk::electrum_client::Client::from_config(electrum_rpc_url.as_str(), config)
             .context("Failed to initialize Electrum RPC client")?;
 
         let db = bdk::sled::open(wallet_dir)?.open_tree(SLED_TREE_NAME)?;

swap/src/cli/event_loop.rs

@@ -54,7 +54,7 @@ impl EventLoop {
     ) -> Result<(Self, EventLoopHandle)> {
         let execution_setup = bmrng::channel_with_timeout(1, Duration::from_secs(60));
         let transfer_proof = bmrng::channel_with_timeout(1, Duration::from_secs(60));
-        let encrypted_signature = bmrng::channel_with_timeout(1, Duration::from_secs(60));
+        let encrypted_signature = bmrng::channel(1);
         let quote = bmrng::channel_with_timeout(1, Duration::from_secs(60));
 
         let event_loop = EventLoop {
@@ -248,7 +248,7 @@ impl EventLoopHandle {
     pub async fn send_encrypted_signature(
         &mut self,
         tx_redeem_encsig: EncryptedSignature,
-    ) -> Result<()> {
+    ) -> Result<(), bmrng::error::RequestError<EncryptedSignature>> {
         Ok(self
             .encrypted_signature
             .send_receive(tx_redeem_encsig)

swap/src/protocol/alice/swap.rs

@@ -195,7 +195,8 @@ where
             select! {
                 biased; // make sure the cancel timelock expiry future is polled first
 
-                _ = tx_lock_status.wait_until_confirmed_with(state3.cancel_timelock) => {
+                result = tx_lock_status.wait_until_confirmed_with(state3.cancel_timelock) => {
+                    let _ = result?;
                     AliceState::CancelTimelockExpired {
                         monero_wallet_restore_blockheight,
                         transfer_proof,

swap/src/protocol/bob/swap.rs

@@ -128,7 +128,7 @@ async fn next_state(
 
                         let state4 = state3.cancel();
                         BobState::CancelTimelockExpired(state4)
-                    }
+                    },
                 }
             } else {
                 let state4 = state3.cancel();
@@ -159,7 +159,8 @@ async fn next_state(
                             },
                         }
                     }
-                    _ = tx_lock_status.wait_until_confirmed_with(state.cancel_timelock) => {
+                    result = tx_lock_status.wait_until_confirmed_with(state.cancel_timelock) => {
+                        let _ = result?;
                         BobState::CancelTimelockExpired(state.cancel())
                     }
                 }
@@ -175,10 +176,15 @@ async fn next_state(
                 // Bob sends Alice his key
 
                 select! {
-                    _ = event_loop_handle.send_encrypted_signature(state.tx_redeem_encsig()) => {
+                    result = event_loop_handle.send_encrypted_signature(state.tx_redeem_encsig()) => {
-                        BobState::EncSigSent(state)
+                        match result {
+                            Ok(_) => BobState::EncSigSent(state),
+                            Err(bmrng::error::RequestError::RecvError | bmrng::error::RequestError::SendError(_)) => bail!("Failed to communicate encrypted signature through event loop channel"),
+                            Err(bmrng::error::RequestError::RecvTimeoutError) => unreachable!("We construct the channel with no timeout"),
+                        }
                     },
-                    _ = tx_lock_status.wait_until_confirmed_with(state.cancel_timelock) => {
+                    result = tx_lock_status.wait_until_confirmed_with(state.cancel_timelock) => {
+                        let _ = result?;
                         BobState::CancelTimelockExpired(state.cancel())
                     }
                 }
@@ -194,7 +200,8 @@ async fn next_state(
                     state5 = state.watch_for_redeem_btc(bitcoin_wallet) => {
                         BobState::BtcRedeemed(state5?)
                     },
-                    _ = tx_lock_status.wait_until_confirmed_with(state.cancel_timelock) => {
+                    result = tx_lock_status.wait_until_confirmed_with(state.cancel_timelock) => {
+                        let _ = result?;
                         BobState::CancelTimelockExpired(state.cancel())
                     }
                 }