Implement traits Receive{BitcoinRedeemEncsig, TransferProof}

Unfortunately, I had to put the wrap the swarm in Alice's `Network`
struct in an `Arc<Mutex<T>>` in order to be able to use `backoff` to
control the retry mechanism. This is because the stream of events
cannot be turned into a `SharedFuture` (unlike Bob's).

It would be good to find an alternative solution.

swap/src/alice.rs

@@ -2,6 +2,7 @@
 //! Alice holds XMR and wishes receive BTC.
 use anyhow::Result;
 use async_trait::async_trait;
+use backoff::{future::FutureOperation as _, ExponentialBackoff};
 use genawaiter::GeneratorState;
 use libp2p::{
     core::{identity::Keypair, Multiaddr},
@@ -50,17 +51,20 @@ pub async fn swap(
     punish_address: ::bitcoin::Address,
 ) -> Result<()> {
     struct Network {
-        swarm: Swarm,
+        swarm: Arc<Mutex<Swarm>>,
         channel: Option<ResponseChannel<AliceToBob>>,
     }
 
     impl Network {
-        pub fn send_message2(&mut self, proof: monero::TransferProof) {
+        pub async fn send_message2(&mut self, proof: monero::TransferProof) {
             match self.channel.take() {
                 None => warn!("Channel not found, did you call this twice?"),
-                Some(channel) => self.swarm.send_message2(channel, alice::Message2 {
+                Some(channel) => {
+                    let mut guard = self.swarm.lock().await;
+                    guard.send_message2(channel, alice::Message2 {
                         tx_lock_proof: proof,
-                }),
+                    })
+                }
             }
         }
     }
@@ -68,7 +72,27 @@ pub async fn swap(
     #[async_trait]
     impl ReceiveBitcoinRedeemEncsig for Network {
         async fn receive_bitcoin_redeem_encsig(&mut self) -> xmr_btc::bitcoin::EncryptedSignature {
-            todo!()
+            #[derive(Debug)]
+            struct UnexpectedMessage;
+
+            (|| async {
+                let mut guard = self.swarm.lock().await;
+                let encsig = match guard.next().await {
+                    OutEvent::Message3(msg) => msg.tx_redeem_encsig,
+                    other => {
+                        warn!("Expected Bob's Message3, got: {:?}", other);
+                        return Err(backoff::Error::Transient(UnexpectedMessage));
+                    }
+                };
+
+                Result::<_, backoff::Error<UnexpectedMessage>>::Ok(encsig)
+            })
+            .retry(ExponentialBackoff {
+                max_elapsed_time: None,
+                ..Default::default()
+            })
+            .await
+            .expect("transient errors to be retried")
         }
     }
 
@@ -144,7 +168,7 @@ pub async fn swap(
     info!("Handshake complete, we now have State3 for Alice.");
 
     let network = Arc::new(Mutex::new(Network {
-        swarm,
+        swarm: Arc::new(Mutex::new(swarm)),
         channel: Some(channel),
     }));
 
@@ -171,7 +195,7 @@ pub async fn swap(
                     .await?;
 
                 let mut guard = network.as_ref().lock().await;
-                guard.send_message2(transfer_proof);
+                guard.send_message2(transfer_proof).await;
             }
 
             GeneratorState::Yielded(Action::RedeemBtc(tx)) => {

swap/src/bob.rs

@@ -2,16 +2,17 @@
 //! Bob holds BTC and wishes receive XMR.
 use anyhow::Result;
 use async_trait::async_trait;
+use backoff::{future::FutureOperation as _, ExponentialBackoff};
 use futures::{
     channel::mpsc::{Receiver, Sender},
-    StreamExt,
+    FutureExt, StreamExt,
 };
 use genawaiter::GeneratorState;
 use libp2p::{core::identity::Keypair, Multiaddr, NetworkBehaviour, PeerId};
 use rand::rngs::OsRng;
 use std::{process, sync::Arc};
 use tokio::sync::Mutex;
-use tracing::{debug, info};
+use tracing::{debug, info, warn};
 
 mod amounts;
 mod message0;
@@ -52,7 +53,28 @@ pub async fn swap(
     #[async_trait]
     impl ReceiveTransferProof for Network {
         async fn receive_transfer_proof(&mut self) -> monero::TransferProof {
-            todo!()
+            #[derive(Debug)]
+            struct UnexpectedMessage;
+
+            let future = self.0.next().shared();
+
+            (|| async {
+                let proof = match future.clone().await {
+                    OutEvent::Message2(msg) => msg.tx_lock_proof,
+                    other => {
+                        warn!("Expected Alice's Message2, got: {:?}", other);
+                        return Err(backoff::Error::Transient(UnexpectedMessage));
+                    }
+                };
+
+                Result::<_, backoff::Error<UnexpectedMessage>>::Ok(proof)
+            })
+            .retry(ExponentialBackoff {
+                max_elapsed_time: None,
+                ..Default::default()
+            })
+            .await
+            .expect("transient errors to be retried")
         }
     }
 
@@ -193,7 +215,7 @@ fn new_swarm() -> Result<Swarm> {
 }
 
 #[allow(clippy::large_enum_variant)]
-#[derive(Debug)]
+#[derive(Debug, Clone)]
 pub enum OutEvent {
     ConnectionEstablished(PeerId),
     Amounts(SwapAmounts),

xmr-btc/tests/on_chain.rs

@@ -168,7 +168,7 @@ async fn swap_as_alice(
 }
 
 async fn swap_as_bob(
-    network: BobNetwork,
+    network: Arc<Mutex<BobNetwork>>,
     mut sender: Sender<EncryptedSignature>,
     monero_wallet: Arc<harness::wallet::monero::Wallet>,
     bitcoin_wallet: Arc<harness::wallet::bitcoin::Wallet>,
@@ -274,11 +274,9 @@ async fn on_chain_happy_path() {
     let (alice_network, bob_sender) = Network::<EncryptedSignature>::new();
     let (bob_network, alice_sender) = Network::<TransferProof>::new();
 
-    let alice_network = Arc::new(Mutex::new(alice_network));
-
     try_join(
         swap_as_alice(
-            alice_network,
+            Arc::new(Mutex::new(alice_network)),
             alice_sender,
             alice_monero_wallet.clone(),
             alice_bitcoin_wallet.clone(),
@@ -286,7 +284,7 @@ async fn on_chain_happy_path() {
             alice,
         ),
         swap_as_bob(
-            bob_network,
+            Arc::new(Mutex::new(bob_network)),
             bob_sender,
             bob_monero_wallet.clone(),
             bob_bitcoin_wallet.clone(),
@@ -367,11 +365,9 @@ async fn on_chain_both_refund_if_alice_never_redeems() {
     let (alice_network, bob_sender) = Network::<EncryptedSignature>::new();
     let (bob_network, alice_sender) = Network::<TransferProof>::new();
 
-    let alice_network = Arc::new(Mutex::new(alice_network));
-
     try_join(
         swap_as_alice(
-            alice_network,
+            Arc::new(Mutex::new(alice_network)),
             alice_sender,
             alice_monero_wallet.clone(),
             alice_bitcoin_wallet.clone(),
@@ -382,7 +378,7 @@ async fn on_chain_both_refund_if_alice_never_redeems() {
             alice,
         ),
         swap_as_bob(
-            bob_network,
+            Arc::new(Mutex::new(bob_network)),
             bob_sender,
             bob_monero_wallet.clone(),
             bob_bitcoin_wallet.clone(),
@@ -464,10 +460,8 @@ async fn on_chain_alice_punishes_if_bob_never_acts_after_fund() {
     let (alice_network, bob_sender) = Network::<EncryptedSignature>::new();
     let (bob_network, alice_sender) = Network::<TransferProof>::new();
 
-    let alice_network = Arc::new(Mutex::new(alice_network));
-
     let alice_swap = swap_as_alice(
-        alice_network,
+        Arc::new(Mutex::new(alice_network)),
         alice_sender,
         alice_monero_wallet.clone(),
         alice_bitcoin_wallet.clone(),
@@ -475,7 +469,7 @@ async fn on_chain_alice_punishes_if_bob_never_acts_after_fund() {
         alice,
     );
     let bob_swap = swap_as_bob(
-        bob_network,
+        Arc::new(Mutex::new(bob_network)),
         bob_sender,
         bob_monero_wallet.clone(),
         bob_bitcoin_wallet.clone(),