Save state for Bob at specific points in the swap

swap/Cargo.toml

@@ -19,7 +19,7 @@ genawaiter = "0.99.1"
 libp2p = { version = "0.29", default-features = false, features = ["tcp-tokio", "yamux", "mplex", "dns", "noise", "request-response"] }
 libp2p-tokio-socks5 = "0.4"
 log = { version = "0.4", features = ["serde"] }
-monero = "0.9"
+monero = { version = "0.9", features = ["serde_support"] }
 monero-harness = { path = "../monero-harness" }
 rand = "0.7"
 reqwest = { version = "0.10", default-features = false, features = ["socks"] }

swap/src/alice.rs

@@ -31,6 +31,7 @@ use crate::{
         transport::SwapTransport,
         TokioExecutor,
     },
+    storage::Database,
     SwapAmounts, PUNISH_TIMELOCK, REFUND_TIMELOCK,
 };
 use xmr_btc::{
@@ -43,6 +44,7 @@ use xmr_btc::{
 pub async fn swap(
     bitcoin_wallet: Arc<bitcoin::Wallet>,
     monero_wallet: Arc<monero::Wallet>,
+    _db: Database<crate::storage::Alice>,
     listen: Multiaddr,
     transport: SwapTransport,
     behaviour: Alice,

swap/src/bob.rs

@@ -22,14 +22,14 @@ mod message3;
 
 use self::{amounts::*, message0::*, message1::*, message2::*, message3::*};
 use crate::{
-    bitcoin,
+    bitcoin::{self, TX_LOCK_MINE_TIMEOUT},
-    bitcoin::TX_LOCK_MINE_TIMEOUT,
     monero,
     network::{
         peer_tracker::{self, PeerTracker},
         transport::SwapTransport,
         TokioExecutor,
     },
+    storage::{self, Database},
     Cmd, Rsp, SwapAmounts, PUNISH_TIMELOCK, REFUND_TIMELOCK,
 };
 use xmr_btc::{
@@ -43,6 +43,7 @@ use xmr_btc::{
 pub async fn swap(
     bitcoin_wallet: Arc<bitcoin::Wallet>,
     monero_wallet: Arc<monero::Wallet>,
+    db: Database<storage::Bob>,
     btc: u64,
     addr: Multiaddr,
     mut cmd_tx: Sender<Cmd>,
@@ -141,6 +142,9 @@ pub async fn swap(
         other => panic!("unexpected event: {:?}", other),
     };
 
+    db.insert_latest_state(&storage::Bob::Handshaken(state2.clone()))
+        .await?;
+
     swarm.send_message2(alice.clone(), state2.next_message());
 
     info!("Handshake complete");
@@ -151,7 +155,7 @@ pub async fn swap(
         network.clone(),
         monero_wallet.clone(),
         bitcoin_wallet.clone(),
-        state2,
+        state2.clone(),
         TX_LOCK_MINE_TIMEOUT,
     );
 
@@ -166,8 +170,17 @@ pub async fn swap(
                 let _ = bitcoin_wallet
                     .broadcast_signed_transaction(signed_tx_lock)
                     .await?;
+                db.insert_latest_state(&storage::Bob::BtcLocked(state2.clone()))
+                    .await?;
             }
             GeneratorState::Yielded(bob::Action::SendBtcRedeemEncsig(tx_redeem_encsig)) => {
+                // FIXME: We _know_ that this action is only yielded if the monero has been
+                // locked. This only works because we know that this is the case, but it may be
+                // cleaner to save the state inside an implementation of `watch_for_transfer` or
+                // modify the library code to make this easier
+                db.insert_latest_state(&storage::Bob::XmrLocked(state2.clone()))
+                    .await?;
+
                 let mut guard = network.as_ref().lock().await;
                 guard.0.send_message3(alice.clone(), tx_redeem_encsig);
                 info!("Sent Bitcoin redeem encsig");
@@ -185,21 +198,41 @@ pub async fn swap(
                 spend_key,
                 view_key,
             }) => {
+                // FIXME: We _know_ that this action is only yielded if the bitcoin has been
+                // redeemed. This only works because we know that this is the case, but it may
+                // be cleaner to save the state inside an implementation of `watch_for_transfer`
+                // or modify the library code to make this easier
+                db.insert_latest_state(&storage::Bob::BtcRedeemed(state2.clone()))
+                    .await?;
+
                 monero_wallet
                     .create_and_load_wallet_for_output(spend_key, view_key)
                     .await?;
             }
             GeneratorState::Yielded(bob::Action::CancelBtc(tx_cancel)) => {
+                db.insert_latest_state(&storage::Bob::BtcRefundable(state2.clone()))
+                    .await?;
+
                 let _ = bitcoin_wallet
                     .broadcast_signed_transaction(tx_cancel)
                     .await?;
+
+                db.insert_latest_state(&storage::Bob::BtcRefundable(state2.clone()))
+                    .await?;
             }
             GeneratorState::Yielded(bob::Action::RefundBtc(tx_refund)) => {
+                db.insert_latest_state(&storage::Bob::BtcRefundable(state2.clone()))
+                    .await?;
+
                 let _ = bitcoin_wallet
                     .broadcast_signed_transaction(tx_refund)
                     .await?;
             }
-            GeneratorState::Complete(()) => return Ok(()),
+            GeneratorState::Complete(()) => {
+                db.insert_latest_state(&storage::Bob::SwapComplete).await?;
+
+                return Ok(());
+            }
         }
     }
 }

swap/src/main.rs

@@ -27,6 +27,7 @@ use swap::{
     network::transport::{build, build_tor, SwapTransport},
     Cmd, Rsp, SwapAmounts,
 };
+use tempfile::tempdir;
 use tracing::info;
 
 mod cli;
@@ -80,9 +81,12 @@ async fn main() -> Result<()> {
 
             let monero_wallet = Arc::new(monero::Wallet::new(monerod_url));
 
+            let db = Database::open(db_dir.path()).unwrap();
+
             swap_as_alice(
                 bitcoin_wallet,
                 monero_wallet,
+                db
                 listen_addr,
                 transport,
                 behaviour,
@@ -113,9 +117,12 @@ async fn main() -> Result<()> {
 
             let monero_wallet = Arc::new(monero::Wallet::new(monerod_url));
 
+            let db = Database::open(db_dir.path()).unwrap();
+
             swap_as_bob(
                 bitcoin_wallet,
                 monero_wallet,
+                db
                 satoshis,
                 alice_addr,
                 transport,
@@ -149,6 +156,7 @@ async fn create_tor_service(
 async fn swap_as_alice(
     bitcoin_wallet: Arc<swap::bitcoin::Wallet>,
     monero_wallet: Arc<swap::monero::Wallet>,
+    db: Database<storage::Alice>,
     addr: Multiaddr,
     transport: SwapTransport,
     behaviour: Alice,
@@ -159,6 +167,7 @@ async fn swap_as_alice(
 async fn swap_as_bob(
     bitcoin_wallet: Arc<swap::bitcoin::Wallet>,
     monero_wallet: Arc<swap::monero::Wallet>,
+    db: Database<storage::Bob>,
     sats: u64,
     alice: Multiaddr,
     transport: SwapTransport,
@@ -169,6 +178,7 @@ async fn swap_as_bob(
     tokio::spawn(bob::swap(
         bitcoin_wallet,
         monero_wallet,
+        db,
         sats,
         alice,
         cmd_tx,

swap/src/storage.rs

@@ -1,6 +1,36 @@
 use anyhow::{anyhow, Context, Result};
-use serde::{de::DeserializeOwned, Serialize};
+use serde::{de::DeserializeOwned, Deserialize, Serialize};
 use std::path::Path;
+use xmr_btc::{alice, bitcoin::EncryptedSignature, bob, serde::monero_private_key};
+
+#[derive(Clone, Debug, Deserialize, Serialize)]
+pub enum Bob {
+    Handshaken(bob::State2),
+    BtcLocked(bob::State2),
+    XmrLocked(bob::State2),
+    BtcRedeemed(bob::State2),
+    BtcRefundable(bob::State2),
+    SwapComplete,
+}
+
+#[allow(clippy::large_enum_variant)]
+#[derive(Clone, Debug, Deserialize, Serialize)]
+pub enum Alice {
+    Handshaken(alice::State3),
+    BtcLocked(alice::State3),
+    XmrLocked(alice::State3),
+    ReceivedEncSig {
+        state: alice::State3,
+        enc_sig: EncryptedSignature,
+    },
+    BtcCancelled(alice::State3),
+    BtcRefunded {
+        state: alice::State3,
+        #[serde(with = "monero_private_key")]
+        s_b: monero::PrivateKey,
+    },
+    SwapComplete,
+}
 
 pub struct Database<T>
 where

xmr-btc/src/bob.rs

@@ -495,7 +495,7 @@ impl State1 {
     }
 }
 
-#[derive(Debug, Deserialize, Serialize)]
+#[derive(Debug, Clone, Deserialize, Serialize)]
 pub struct State2 {
     pub A: bitcoin::PublicKey,
     pub b: bitcoin::SecretKey,