Execute Bob's on-chain protocol after handshake

Co-authored-by: Tobin C. Harding <tobin@coblox.tech>

swap/src/alice.rs

@@ -18,10 +18,13 @@ mod amounts;
 mod message0;
 mod message1;
 mod message2;
+mod message3;
 
-use self::{amounts::*, message0::*, message1::*, message2::*};
+use self::{amounts::*, message0::*, message1::*, message2::*, message3::*};
 use crate::{
-    bitcoin, monero,
+    bitcoin,
+    bitcoin::TX_LOCK_MINE_TIMEOUT,
+    monero,
     network::{
         peer_tracker::{self, PeerTracker},
         request_response::AliceToBob,
@@ -117,7 +120,6 @@ pub async fn swap(
     );
     swarm.set_state0(state0.clone());
 
-    // TODO: Can we verify message 0 before calling this so we never fail?
     let state1 = state0.receive(message0).expect("failed to receive msg 0");
 
     let (state2, channel) = match swarm.next().await {
@@ -146,8 +148,12 @@ pub async fn swap(
         channel: Some(channel),
     }));
 
-    let mut action_generator =
-        action_generator(network.clone(), bitcoin_wallet.clone(), state3, 3600);
+    let mut action_generator = action_generator(
+        network.clone(),
+        bitcoin_wallet.clone(),
+        state3,
+        TX_LOCK_MINE_TIMEOUT,
+    );
 
     loop {
         let state = action_generator.async_resume().await;
@@ -242,6 +248,7 @@ pub enum OutEvent {
         msg: bob::Message2,
         channel: ResponseChannel<AliceToBob>,
     },
+    Message3(bob::Message3),
 }
 
 impl From<peer_tracker::OutEvent> for OutEvent {
@@ -284,6 +291,14 @@ impl From<message2::OutEvent> for OutEvent {
     }
 }
 
+impl From<message3::OutEvent> for OutEvent {
+    fn from(event: message3::OutEvent) -> Self {
+        match event {
+            message3::OutEvent::Msg(msg) => OutEvent::Message3(msg),
+        }
+    }
+}
+
 /// A `NetworkBehaviour` that represents an XMR/BTC swap node as Alice.
 #[derive(NetworkBehaviour)]
 #[behaviour(out_event = "OutEvent", event_process = false)]
@@ -294,6 +309,7 @@ pub struct Alice {
     message0: Message0,
     message1: Message1,
     message2: Message2,
+    message3: Message3,
     #[behaviour(ignore)]
     identity: Keypair,
 }
@@ -347,6 +363,7 @@ impl Default for Alice {
             message0: Message0::default(),
             message1: Message1::default(),
             message2: Message2::default(),
+            message3: Message3::default(),
             identity,
         }
     }

swap/src/alice/message3.rs

@@ -0,0 +1,94 @@
+use libp2p::{
+    request_response::{
+        handler::RequestProtocol, ProtocolSupport, RequestResponse, RequestResponseConfig,
+        RequestResponseEvent, RequestResponseMessage,
+    },
+    swarm::{NetworkBehaviourAction, NetworkBehaviourEventProcess, PollParameters},
+    NetworkBehaviour,
+};
+use std::{
+    collections::VecDeque,
+    task::{Context, Poll},
+    time::Duration,
+};
+use tracing::{debug, error};
+
+use crate::network::request_response::{AliceToBob, BobToAlice, Codec, Protocol, TIMEOUT};
+use xmr_btc::bob;
+
+#[derive(Debug)]
+pub enum OutEvent {
+    Msg(bob::Message3),
+}
+
+/// A `NetworkBehaviour` that represents receiving of message 3 from Bob.
+#[derive(NetworkBehaviour)]
+#[behaviour(out_event = "OutEvent", poll_method = "poll")]
+#[allow(missing_debug_implementations)]
+pub struct Message3 {
+    rr: RequestResponse<Codec>,
+    #[behaviour(ignore)]
+    events: VecDeque<OutEvent>,
+}
+
+impl Message3 {
+    fn poll(
+        &mut self,
+        _: &mut Context<'_>,
+        _: &mut impl PollParameters,
+    ) -> Poll<NetworkBehaviourAction<RequestProtocol<Codec>, OutEvent>> {
+        if let Some(event) = self.events.pop_front() {
+            return Poll::Ready(NetworkBehaviourAction::GenerateEvent(event));
+        }
+
+        Poll::Pending
+    }
+}
+
+impl Default for Message3 {
+    fn default() -> Self {
+        let timeout = Duration::from_secs(TIMEOUT);
+        let mut config = RequestResponseConfig::default();
+        config.set_request_timeout(timeout);
+
+        Self {
+            rr: RequestResponse::new(
+                Codec::default(),
+                vec![(Protocol, ProtocolSupport::Full)],
+                config,
+            ),
+            events: Default::default(),
+        }
+    }
+}
+
+impl NetworkBehaviourEventProcess<RequestResponseEvent<BobToAlice, AliceToBob>> for Message3 {
+    fn inject_event(&mut self, event: RequestResponseEvent<BobToAlice, AliceToBob>) {
+        match event {
+            RequestResponseEvent::Message {
+                message:
+                    RequestResponseMessage::Request {
+                        request, channel, ..
+                    },
+                ..
+            } => match request {
+                BobToAlice::Message3(msg) => {
+                    self.events.push_back(OutEvent::Msg(msg));
+                    // Send back empty response so that the request/response protocol completes.
+                    self.rr.send_response(channel, AliceToBob::Message3);
+                }
+                other => debug!("got request: {:?}", other),
+            },
+            RequestResponseEvent::Message {
+                message: RequestResponseMessage::Response { .. },
+                ..
+            } => panic!("Alice should not get a Response"),
+            RequestResponseEvent::InboundFailure { error, .. } => {
+                error!("Inbound failure: {:?}", error);
+            }
+            RequestResponseEvent::OutboundFailure { error, .. } => {
+                error!("Outbound failure: {:?}", error);
+            }
+        }
+    }
+}

swap/src/bitcoin.rs

@@ -12,6 +12,8 @@ use xmr_btc::bitcoin::{
     TransactionBlockHeight, TxLock, Txid, WatchForRawTransaction,
 };
 
+pub const TX_LOCK_MINE_TIMEOUT: u64 = 3600;
+
 // This is cut'n'paste from xmr_btc/tests/harness/wallet/bitcoin.rs
 
 #[derive(Debug)]

swap/src/bob.rs

@@ -1,46 +1,61 @@
 //! Run an XMR/BTC swap in the role of Bob.
 //! Bob holds BTC and wishes receive XMR.
 use anyhow::Result;
+use async_trait::async_trait;
 use futures::{
     channel::mpsc::{Receiver, Sender},
     StreamExt,
 };
+use genawaiter::GeneratorState;
 use libp2p::{core::identity::Keypair, Multiaddr, NetworkBehaviour, PeerId};
 use rand::rngs::OsRng;
-use std::{process, thread};
+use std::{process, sync::Arc};
+use tokio::sync::Mutex;
 use tracing::{debug, info};
 
 mod amounts;
 mod message0;
 mod message1;
 mod message2;
+mod message3;
 
-use self::{amounts::*, message0::*, message1::*, message2::*};
+use self::{amounts::*, message0::*, message1::*, message2::*, message3::*};
 use crate::{
+    bitcoin,
+    bitcoin::TX_LOCK_MINE_TIMEOUT,
+    monero,
     network::{
         peer_tracker::{self, PeerTracker},
         transport, TokioExecutor,
     },
-    Cmd, Rsp, SwapAmounts, PUNISH_TIMELOCK, REFUND_TIMELOCK,
+    Cmd, Never, Rsp, SwapAmounts, PUNISH_TIMELOCK, REFUND_TIMELOCK,
 };
 use xmr_btc::{
     alice,
-    bitcoin::{BroadcastSignedTransaction, BuildTxLockPsbt, SignTxLock},
-    bob::{self, State0},
+    bitcoin::{BroadcastSignedTransaction, EncryptedSignature, SignTxLock},
+    bob::{self, action_generator, ReceiveTransferProof, State0},
+    monero::CreateWalletForOutput,
 };
 
 // FIXME: This whole function is horrible, needs total re-write.
-pub async fn swap<W>(
+pub async fn swap(
+    bitcoin_wallet: Arc<bitcoin::Wallet>,
+    monero_wallet: Arc<monero::Wallet>,
     btc: u64,
     addr: Multiaddr,
     mut cmd_tx: Sender<Cmd>,
     mut rsp_rx: Receiver<Rsp>,
     refund_address: ::bitcoin::Address,
-    wallet: W,
-) -> Result<()>
-where
-    W: BuildTxLockPsbt + SignTxLock + BroadcastSignedTransaction + Send + Sync + 'static,
-{
+) -> Result<()> {
+    struct Network(Swarm);
+
+    #[async_trait]
+    impl ReceiveTransferProof for Network {
+        async fn receive_transfer_proof(&mut self) -> monero::TransferProof {
+            todo!()
+        }
+    }
+
     let mut swarm = new_swarm()?;
 
     libp2p::Swarm::dial_addr(&mut swarm, addr)?;
@@ -82,11 +97,7 @@ where
 
     swarm.send_message0(alice.clone(), state0.next_message(rng));
     let state1 = match swarm.next().await {
-        OutEvent::Message0(msg) => {
-            // TODO: Verify the response message before calling receive() and handle any
-            // error gracefully.
-            state0.receive(&wallet, msg).await?
-        }
+        OutEvent::Message0(msg) => state0.receive(bitcoin_wallet.as_ref(), msg).await?,
         other => panic!("unexpected event: {:?}", other),
     };
 
@@ -102,8 +113,53 @@ where
 
     info!("Handshake complete, we now have State2 for Bob.");
 
-    thread::park();
-    Ok(())
+    let network = Arc::new(Mutex::new(Network(swarm)));
+
+    let mut action_generator = action_generator(
+        network.clone(),
+        monero_wallet.clone(),
+        bitcoin_wallet.clone(),
+        state2,
+        TX_LOCK_MINE_TIMEOUT,
+    );
+
+    loop {
+        let state = action_generator.async_resume().await;
+
+        info!("resumed execution of bob generator, got: {:?}", state);
+
+        match state {
+            GeneratorState::Yielded(bob::Action::LockBtc(tx_lock)) => {
+                let signed_tx_lock = bitcoin_wallet.sign_tx_lock(tx_lock).await?;
+                let _ = bitcoin_wallet
+                    .broadcast_signed_transaction(signed_tx_lock)
+                    .await?;
+            }
+            GeneratorState::Yielded(bob::Action::SendBtcRedeemEncsig(tx_redeem_encsig)) => {
+                let mut guard = network.as_ref().lock().await;
+                guard.0.send_message3(alice.clone(), tx_redeem_encsig);
+            }
+            GeneratorState::Yielded(bob::Action::CreateXmrWalletForOutput {
+                spend_key,
+                view_key,
+            }) => {
+                monero_wallet
+                    .create_and_load_wallet_for_output(spend_key, view_key)
+                    .await?;
+            }
+            GeneratorState::Yielded(bob::Action::CancelBtc(tx_cancel)) => {
+                let _ = bitcoin_wallet
+                    .broadcast_signed_transaction(tx_cancel)
+                    .await?;
+            }
+            GeneratorState::Yielded(bob::Action::RefundBtc(tx_refund)) => {
+                let _ = bitcoin_wallet
+                    .broadcast_signed_transaction(tx_refund)
+                    .await?;
+            }
+            GeneratorState::Complete(()) => return Ok(()),
+        }
+    }
 }
 
 pub type Swarm = libp2p::Swarm<Bob>;
@@ -188,6 +244,12 @@ impl From<message2::OutEvent> for OutEvent {
     }
 }
 
+impl From<Never> for OutEvent {
+    fn from(_: Never) -> Self {
+        panic!("not ever")
+    }
+}
+
 /// A `NetworkBehaviour` that represents an XMR/BTC swap node as Bob.
 #[derive(NetworkBehaviour)]
 #[behaviour(out_event = "OutEvent", event_process = false)]
@@ -198,6 +260,7 @@ pub struct Bob {
     message0: Message0,
     message1: Message1,
     message2: Message2,
+    message3: Message3,
     #[behaviour(ignore)]
     identity: Keypair,
 }
@@ -233,6 +296,12 @@ impl Bob {
         self.message2.send(alice, msg)
     }
 
+    /// Sends Bob's fourth message to Alice.
+    pub fn send_message3(&mut self, alice: PeerId, tx_redeem_encsig: EncryptedSignature) {
+        let msg = bob::Message3 { tx_redeem_encsig };
+        self.message3.send(alice, msg)
+    }
+
     /// Returns Alice's peer id if we are connected.
     pub fn peer_id_of_alice(&self) -> Option<PeerId> {
         self.pt.counterparty_peer_id()
@@ -249,6 +318,7 @@ impl Default for Bob {
             message0: Message0::default(),
             message1: Message1::default(),
             message2: Message2::default(),
+            message3: Message3::default(),
             identity,
         }
     }

swap/src/bob/message3.rs

@@ -0,0 +1,84 @@
+use libp2p::{
+    request_response::{
+        handler::RequestProtocol, ProtocolSupport, RequestResponse, RequestResponseConfig,
+        RequestResponseEvent, RequestResponseMessage,
+    },
+    swarm::{NetworkBehaviourAction, NetworkBehaviourEventProcess, PollParameters},
+    NetworkBehaviour, PeerId,
+};
+use std::{
+    task::{Context, Poll},
+    time::Duration,
+};
+use tracing::{debug, error};
+
+use crate::{
+    network::request_response::{AliceToBob, BobToAlice, Codec, Protocol, TIMEOUT},
+    Never,
+};
+use xmr_btc::bob;
+
+/// A `NetworkBehaviour` that represents sending message 3 to Alice.
+#[derive(NetworkBehaviour)]
+#[behaviour(out_event = "Never", poll_method = "poll")]
+#[allow(missing_debug_implementations)]
+pub struct Message3 {
+    rr: RequestResponse<Codec>,
+}
+
+impl Message3 {
+    pub fn send(&mut self, alice: PeerId, msg: bob::Message3) {
+        let msg = BobToAlice::Message3(msg);
+        let _id = self.rr.send_request(&alice, msg);
+    }
+
+    // TODO: Do we need a custom implementation if we are not bubbling any out
+    // events?
+    fn poll(
+        &mut self,
+        _: &mut Context<'_>,
+        _: &mut impl PollParameters,
+    ) -> Poll<NetworkBehaviourAction<RequestProtocol<Codec>, Never>> {
+        Poll::Pending
+    }
+}
+
+impl Default for Message3 {
+    fn default() -> Self {
+        let timeout = Duration::from_secs(TIMEOUT);
+        let mut config = RequestResponseConfig::default();
+        config.set_request_timeout(timeout);
+
+        Self {
+            rr: RequestResponse::new(
+                Codec::default(),
+                vec![(Protocol, ProtocolSupport::Full)],
+                config,
+            ),
+        }
+    }
+}
+
+impl NetworkBehaviourEventProcess<RequestResponseEvent<BobToAlice, AliceToBob>> for Message3 {
+    fn inject_event(&mut self, event: RequestResponseEvent<BobToAlice, AliceToBob>) {
+        match event {
+            RequestResponseEvent::Message {
+                message: RequestResponseMessage::Request { .. },
+                ..
+            } => panic!("Bob should never get a request from Alice"),
+            RequestResponseEvent::Message {
+                message: RequestResponseMessage::Response { response, .. },
+                ..
+            } => match response {
+                AliceToBob::Message3 => debug!("Alice correctly responded to message 3"),
+                other => debug!("unexpected response: {:?}", other),
+            },
+            RequestResponseEvent::InboundFailure { error, .. } => {
+                error!("Inbound failure: {:?}", error);
+            }
+            RequestResponseEvent::OutboundFailure { error, .. } => {
+                error!("Outbound failure: {:?}", error);
+            }
+        }
+    }
+}

swap/src/main.rs

@@ -26,7 +26,6 @@ mod trace;
 
 use cli::Options;
 use swap::{alice, bitcoin, bob, monero, Cmd, Rsp, SwapAmounts};
-use xmr_btc::bitcoin::{BroadcastSignedTransaction, BuildTxLockPsbt, SignTxLock};
 
 // TODO: Add root seed file instead of generating new seed each run.
 // TODO: Remove all instances of the todo! macro
@@ -92,28 +91,31 @@ async fn main() -> Result<()> {
     } else {
         info!("running swap node as Bob ...");
 
-        let alice_address = match opt.alice_address {
+        let alice = match opt.alice_address {
             Some(addr) => addr,
             None => bail!("Address required to dial"),
         };
-        let alice_address = multiaddr(&alice_address)?;
+        let alice = multiaddr(&alice)?;
 
         let url = Url::parse(BITCOIND_JSON_RPC_URL).expect("failed to parse url");
         let bitcoin_wallet = bitcoin::Wallet::new("bob", &url)
             .await
             .expect("failed to create bitcoin wallet");
 
+        let monero_wallet = Arc::new(monero::Wallet::localhost(MONERO_WALLET_RPC_PORT));
+
         let refund = bitcoin_wallet
             .new_address()
             .await
             .expect("failed to get new address");
 
+        let bitcoin_wallet = Arc::new(bitcoin_wallet);
         match (opt.piconeros, opt.satoshis) {
             (Some(_), Some(_)) => bail!("Please supply only a single amount to swap"),
             (None, None) => bail!("Please supply an amount to swap"),
             (Some(_picos), _) => todo!("support starting with picos"),
             (None, Some(sats)) => {
-                swap_as_bob(sats, alice_address, refund, bitcoin_wallet).await?;
+                swap_as_bob(bitcoin_wallet, monero_wallet, sats, alice, refund).await?;
             }
         };
     }
@@ -164,18 +166,24 @@ async fn swap_as_alice(
     }
 }
 
-async fn swap_as_bob<W>(
+async fn swap_as_bob(
+    bitcoin_wallet: Arc<swap::bitcoin::Wallet>,
+    monero_wallet: Arc<swap::monero::Wallet>,
     sats: u64,
     alice: Multiaddr,
     refund: ::bitcoin::Address,
-    wallet: W,
-) -> Result<()>
-where
-    W: BuildTxLockPsbt + SignTxLock + BroadcastSignedTransaction + Send + Sync + 'static,
-{
+) -> Result<()> {
     let (cmd_tx, mut cmd_rx) = mpsc::channel(1);
     let (mut rsp_tx, rsp_rx) = mpsc::channel(1);
-    tokio::spawn(bob::swap(sats, alice, cmd_tx, rsp_rx, refund, wallet));
+    tokio::spawn(bob::swap(
+        bitcoin_wallet,
+        monero_wallet,
+        sats,
+        alice,
+        cmd_tx,
+        rsp_rx,
+        refund,
+    ));
 
     loop {
         let read = cmd_rx.next().await;

swap/src/network/request_response.rs

@@ -26,6 +26,7 @@ pub enum BobToAlice {
     Message0(bob::Message0),
     Message1(bob::Message1),
     Message2(bob::Message2),
+    Message3(bob::Message3),
 }
 
 /// Messages Alice sends to Bob.
@@ -36,6 +37,7 @@ pub enum AliceToBob {
     Message0(alice::Message0),
     Message1(alice::Message1),
     Message2(alice::Message2),
+    Message3, // empty response
 }
 
 #[derive(Debug, Clone, Copy, Default)]

xmr-btc/src/bob.rs

@@ -28,7 +28,7 @@ use std::{
     sync::Arc,
     time::Duration,
 };
-use tokio::time::timeout;
+use tokio::{sync::Mutex, time::timeout};
 use tracing::error;
 
 pub mod message;
@@ -62,7 +62,7 @@ pub trait ReceiveTransferProof {
 /// The argument `bitcoin_tx_lock_timeout` is used to determine how long we will
 /// wait for Bob, the caller of this function, to lock up the bitcoin.
 pub fn action_generator<N, M, B>(
-    mut network: N,
+    network: Arc<Mutex<N>>,
     monero_client: Arc<M>,
     bitcoin_client: Arc<B>,
     // TODO: Replace this with a new, slimmer struct?
@@ -85,7 +85,7 @@ pub fn action_generator<N, M, B>(
     bitcoin_tx_lock_timeout: u64,
 ) -> GenBoxed<Action, (), ()>
 where
-    N: ReceiveTransferProof + Send + Sync + 'static,
+    N: ReceiveTransferProof + Send + 'static,
     M: monero::WatchForTransfer + Send + Sync + 'static,
     B: bitcoin::BlockHeight
         + bitcoin::TransactionBlockHeight
@@ -140,14 +140,19 @@ where
             .shared();
             pin_mut!(poll_until_btc_has_expired);
 
-            let transfer_proof = match select(
-                network.receive_transfer_proof(),
-                poll_until_btc_has_expired.clone(),
-            )
-            .await
-            {
-                Either::Left((proof, _)) => proof,
-                Either::Right(_) => return Err(SwapFailed::AfterBtcLock(Reason::BtcExpired)),
+            let transfer_proof = {
+                let mut guard = network.as_ref().lock().await;
+                let transfer_proof = match select(
+                    guard.receive_transfer_proof(),
+                    poll_until_btc_has_expired.clone(),
+                )
+                .await
+                {
+                    Either::Left((proof, _)) => proof,
+                    Either::Right(_) => return Err(SwapFailed::AfterBtcLock(Reason::BtcExpired)),
+                };
+
+                transfer_proof
             };
 
             let S_b_monero = monero::PublicKey::from_private_key(&monero::PrivateKey::from_scalar(

xmr-btc/src/bob/message.rs

@@ -33,9 +33,9 @@ pub struct Message2 {
     pub(crate) tx_cancel_sig: Signature,
 }
 
-#[derive(Clone, Debug)]
+#[derive(Clone, Debug, Serialize, Deserialize)]
 pub struct Message3 {
-    pub(crate) tx_redeem_encsig: EncryptedSignature,
+    pub tx_redeem_encsig: EncryptedSignature,
 }
 
 impl_try_from_parent_enum!(Message0, Message);