Introduce dedicated bob::State6 for cancelling

swap/src/database/bob.rs

@@ -29,8 +29,8 @@ pub enum Bob {
         state4: bob::State4,
     },
     BtcRedeemed(bob::State5),
-    CancelTimelockExpired(bob::State4),
-    BtcCancelled(bob::State4),
+    CancelTimelockExpired(bob::State6),
+    BtcCancelled(bob::State6),
     Done(BobEndState),
 }
 
@@ -38,7 +38,7 @@ pub enum Bob {
 pub enum BobEndState {
     SafelyAborted,
     XmrRedeemed { tx_lock_id: bitcoin::Txid },
-    BtcRefunded(Box<bob::State4>),
+    BtcRefunded(Box<bob::State6>),
     BtcPunished { tx_lock_id: bitcoin::Txid },
 }
 
@@ -60,9 +60,9 @@ impl From<BobState> for Bob {
             BobState::XmrLocked(state4) => Bob::XmrLocked { state4 },
             BobState::EncSigSent(state4) => Bob::EncSigSent { state4 },
             BobState::BtcRedeemed(state5) => Bob::BtcRedeemed(state5),
-            BobState::CancelTimelockExpired(state4) => Bob::CancelTimelockExpired(state4),
-            BobState::BtcCancelled(state4) => Bob::BtcCancelled(state4),
-            BobState::BtcRefunded(state4) => Bob::Done(BobEndState::BtcRefunded(Box::new(state4))),
+            BobState::CancelTimelockExpired(state6) => Bob::CancelTimelockExpired(state6),
+            BobState::BtcCancelled(state6) => Bob::BtcCancelled(state6),
+            BobState::BtcRefunded(state6) => Bob::Done(BobEndState::BtcRefunded(Box::new(state6))),
             BobState::XmrRedeemed { tx_lock_id } => {
                 Bob::Done(BobEndState::XmrRedeemed { tx_lock_id })
             }
@@ -92,12 +92,12 @@ impl From<Bob> for BobState {
             Bob::XmrLocked { state4 } => BobState::XmrLocked(state4),
             Bob::EncSigSent { state4 } => BobState::EncSigSent(state4),
             Bob::BtcRedeemed(state5) => BobState::BtcRedeemed(state5),
-            Bob::CancelTimelockExpired(state4) => BobState::CancelTimelockExpired(state4),
-            Bob::BtcCancelled(state4) => BobState::BtcCancelled(state4),
+            Bob::CancelTimelockExpired(state6) => BobState::CancelTimelockExpired(state6),
+            Bob::BtcCancelled(state6) => BobState::BtcCancelled(state6),
             Bob::Done(end_state) => match end_state {
                 BobEndState::SafelyAborted => BobState::SafelyAborted,
                 BobEndState::XmrRedeemed { tx_lock_id } => BobState::XmrRedeemed { tx_lock_id },
-                BobEndState::BtcRefunded(state4) => BobState::BtcRefunded(*state4),
+                BobEndState::BtcRefunded(state6) => BobState::BtcRefunded(*state6),
                 BobEndState::BtcPunished { tx_lock_id } => BobState::BtcPunished { tx_lock_id },
             },
         }

swap/src/protocol/bob/cancel.rs

@@ -20,12 +20,12 @@ pub async fn cancel(
     db: Database,
     force: bool,
 ) -> Result<Result<(Txid, BobState), Error>> {
-    let state4 = match state {
+    let state6 = match state {
         BobState::BtcLocked(state3) => state3.cancel(),
         BobState::XmrLockProofReceived { state, .. } => state.cancel(),
-        BobState::XmrLocked(state4) => state4,
-        BobState::EncSigSent(state4) => state4,
-        BobState::CancelTimelockExpired(state4) => state4,
+        BobState::XmrLocked(state4) => state4.cancel(),
+        BobState::EncSigSent(state4) => state4.cancel(),
+        BobState::CancelTimelockExpired(state6) => state6,
         _ => bail!(
             "Cannot cancel swap {} because it is in state {} which is not refundable.",
             swap_id,
@@ -34,16 +34,16 @@ pub async fn cancel(
     };
 
     if !force {
-        if let ExpiredTimelocks::None = state4.expired_timelock(bitcoin_wallet.as_ref()).await? {
+        if let ExpiredTimelocks::None = state6.expired_timelock(bitcoin_wallet.as_ref()).await? {
             return Ok(Err(Error::CancelTimelockNotExpiredYet));
         }
 
-        if state4
+        if state6
             .check_for_tx_cancel(bitcoin_wallet.as_ref())
             .await
             .is_ok()
         {
-            let state = BobState::BtcCancelled(state4);
+            let state = BobState::BtcCancelled(state6);
             let db_state = state.into();
             db.insert_latest_state(swap_id, Swap::Bob(db_state)).await?;
 
@@ -51,9 +51,9 @@ pub async fn cancel(
         }
     }
 
-    let txid = state4.submit_tx_cancel(bitcoin_wallet.as_ref()).await?;
+    let txid = state6.submit_tx_cancel(bitcoin_wallet.as_ref()).await?;
 
-    let state = BobState::BtcCancelled(state4);
+    let state = BobState::BtcCancelled(state6);
     let db_state = state.clone().into();
     db.insert_latest_state(swap_id, Swap::Bob(db_state)).await?;
 

swap/src/protocol/bob/refund.rs

@@ -16,14 +16,14 @@ pub async fn refund(
     db: Database,
     force: bool,
 ) -> Result<Result<BobState, SwapNotCancelledYet>> {
-    let state4 = if force {
+    let state6 = if force {
         match state {
             BobState::BtcLocked(state3) => state3.cancel(),
             BobState::XmrLockProofReceived { state, .. } => state.cancel(),
-            BobState::XmrLocked(state4) => state4,
-            BobState::EncSigSent(state4) => state4,
-            BobState::CancelTimelockExpired(state4) => state4,
-            BobState::BtcCancelled(state4) => state4,
+            BobState::XmrLocked(state4) => state4.cancel(),
+            BobState::EncSigSent(state4) => state4.cancel(),
+            BobState::CancelTimelockExpired(state6) => state6,
+            BobState::BtcCancelled(state6) => state6,
             _ => bail!(
                 "Cannot refund swap {} because it is in state {} which is not refundable.",
                 swap_id,
@@ -32,16 +32,16 @@ pub async fn refund(
         }
     } else {
         match state {
-            BobState::BtcCancelled(state4) => state4,
+            BobState::BtcCancelled(state6) => state6,
             _ => {
                 return Ok(Err(SwapNotCancelledYet(swap_id)));
             }
         }
     };
 
-    state4.refund_btc(bitcoin_wallet.as_ref()).await?;
+    state6.refund_btc(bitcoin_wallet.as_ref()).await?;
 
-    let state = BobState::BtcRefunded(state4);
+    let state = BobState::BtcRefunded(state6);
     let db_state = state.clone().into();
 
     db.insert_latest_state(swap_id, Swap::Bob(db_state)).await?;

swap/src/protocol/bob/state.rs

@@ -34,9 +34,9 @@ pub enum BobState {
     XmrLocked(State4),
     EncSigSent(State4),
     BtcRedeemed(State5),
-    CancelTimelockExpired(State4),
-    BtcCancelled(State4),
-    BtcRefunded(State4),
+    CancelTimelockExpired(State6),
+    BtcCancelled(State6),
+    BtcRefunded(State6),
     XmrRedeemed {
         tx_lock_id: bitcoin::Txid,
     },
@@ -357,23 +357,17 @@ impl State3 {
         Ok(())
     }
 
-    pub fn cancel(&self) -> State4 {
-        State4 {
+    pub fn cancel(&self) -> State6 {
+        State6 {
             A: self.A,
             b: self.b.clone(),
             s_b: self.s_b,
-            S_a_bitcoin: self.S_a_bitcoin,
-            v: self.v,
             cancel_timelock: self.cancel_timelock,
             punish_timelock: self.punish_timelock,
             refund_address: self.refund_address.clone(),
-            redeem_address: self.redeem_address.clone(),
             tx_lock: self.tx_lock.clone(),
             tx_cancel_sig_a: self.tx_cancel_sig_a.clone(),
             tx_refund_encsig: self.tx_refund_encsig.clone(),
-            // For cancel scenarios the monero wallet rescan blockchain height is irrelevant for
-            // Bob, because Bob's cancel can only lead to refunding on Bitcoin
-            monero_wallet_restore_blockheight: BlockHeight { height: 0 },
         }
     }
 
@@ -428,29 +422,6 @@ impl State4 {
         self.b.encsign(self.S_a_bitcoin, tx_redeem.digest())
     }
 
-    pub async fn check_for_tx_cancel(
-        &self,
-        bitcoin_wallet: &bitcoin::Wallet,
-    ) -> Result<Transaction> {
-        let tx_cancel =
-            bitcoin::TxCancel::new(&self.tx_lock, self.cancel_timelock, self.A, self.b.public());
-
-        let tx = bitcoin_wallet.get_raw_transaction(tx_cancel.txid()).await?;
-
-        Ok(tx)
-    }
-
-    pub async fn submit_tx_cancel(&self, bitcoin_wallet: &bitcoin::Wallet) -> Result<Txid> {
-        let transaction =
-            bitcoin::TxCancel::new(&self.tx_lock, self.cancel_timelock, self.A, self.b.public())
-                .complete_as_bob(self.A, self.b.clone(), self.tx_cancel_sig_a.clone())
-                .context("Failed to complete Bitcoin cancel transaction")?;
-
-        let (tx_id, _) = bitcoin_wallet.broadcast(transaction, "cancel").await?;
-
-        Ok(tx_id)
-    }
-
     pub async fn watch_for_redeem_btc(&self, bitcoin_wallet: &bitcoin::Wallet) -> Result<State5> {
         let tx_redeem = bitcoin::TxRedeem::new(&self.tx_lock, &self.redeem_address);
         let tx_redeem_encsig = self.b.encsign(self.S_a_bitcoin, tx_redeem.digest());
@@ -505,29 +476,18 @@ impl State4 {
         ))
     }
 
-    pub async fn refund_btc(&self, bitcoin_wallet: &bitcoin::Wallet) -> Result<()> {
-        let tx_cancel =
-            bitcoin::TxCancel::new(&self.tx_lock, self.cancel_timelock, self.A, self.b.public());
-        let tx_refund = bitcoin::TxRefund::new(&tx_cancel, &self.refund_address);
-
-        let adaptor = Adaptor::<HashTranscript<Sha256>, Deterministic<Sha256>>::default();
-
-        let sig_b = self.b.sign(tx_refund.digest());
-        let sig_a =
-            adaptor.decrypt_signature(&self.s_b.to_secpfun_scalar(), self.tx_refund_encsig.clone());
-
-        let signed_tx_refund =
-            tx_refund.add_signatures((self.A, sig_a), (self.b.public(), sig_b))?;
-
-        let (_, finality) = bitcoin_wallet.broadcast(signed_tx_refund, "refund").await?;
-
-        finality.await?;
-
-        Ok(())
+    pub fn cancel(self) -> State6 {
+        State6 {
+            A: self.A,
+            b: self.b,
+            s_b: self.s_b,
+            cancel_timelock: self.cancel_timelock,
+            punish_timelock: self.punish_timelock,
+            refund_address: self.refund_address,
+            tx_lock: self.tx_lock,
+            tx_cancel_sig_a: self.tx_cancel_sig_a,
+            tx_refund_encsig: self.tx_refund_encsig,
         }
-
-    pub fn tx_lock_id(&self) -> bitcoin::Txid {
-        self.tx_lock.txid()
     }
 }
 
@@ -559,3 +519,83 @@ impl State5 {
         self.tx_lock.txid()
     }
 }
+
+#[derive(Debug, Clone, Deserialize, Serialize, PartialEq)]
+pub struct State6 {
+    A: bitcoin::PublicKey,
+    b: bitcoin::SecretKey,
+    s_b: monero::Scalar,
+    cancel_timelock: CancelTimelock,
+    punish_timelock: PunishTimelock,
+    refund_address: bitcoin::Address,
+    tx_lock: bitcoin::TxLock,
+    tx_cancel_sig_a: Signature,
+    tx_refund_encsig: bitcoin::EncryptedSignature,
+}
+
+impl State6 {
+    pub async fn expired_timelock(
+        &self,
+        bitcoin_wallet: &bitcoin::Wallet,
+    ) -> Result<ExpiredTimelocks> {
+        let tx_cancel = TxCancel::new(&self.tx_lock, self.cancel_timelock, self.A, self.b.public());
+
+        let tx_lock_status = bitcoin_wallet.status_of_script(&self.tx_lock).await?;
+        let tx_cancel_status = bitcoin_wallet.status_of_script(&tx_cancel).await?;
+
+        Ok(current_epoch(
+            self.cancel_timelock,
+            self.punish_timelock,
+            tx_lock_status,
+            tx_cancel_status,
+        ))
+    }
+
+    pub async fn check_for_tx_cancel(
+        &self,
+        bitcoin_wallet: &bitcoin::Wallet,
+    ) -> Result<Transaction> {
+        let tx_cancel =
+            bitcoin::TxCancel::new(&self.tx_lock, self.cancel_timelock, self.A, self.b.public());
+
+        let tx = bitcoin_wallet.get_raw_transaction(tx_cancel.txid()).await?;
+
+        Ok(tx)
+    }
+
+    pub async fn submit_tx_cancel(&self, bitcoin_wallet: &bitcoin::Wallet) -> Result<Txid> {
+        let transaction =
+            bitcoin::TxCancel::new(&self.tx_lock, self.cancel_timelock, self.A, self.b.public())
+                .complete_as_bob(self.A, self.b.clone(), self.tx_cancel_sig_a.clone())
+                .context("Failed to complete Bitcoin cancel transaction")?;
+
+        let (tx_id, _) = bitcoin_wallet.broadcast(transaction, "cancel").await?;
+
+        Ok(tx_id)
+    }
+
+    pub async fn refund_btc(&self, bitcoin_wallet: &bitcoin::Wallet) -> Result<()> {
+        let tx_cancel =
+            bitcoin::TxCancel::new(&self.tx_lock, self.cancel_timelock, self.A, self.b.public());
+        let tx_refund = bitcoin::TxRefund::new(&tx_cancel, &self.refund_address);
+
+        let adaptor = Adaptor::<HashTranscript<Sha256>, Deterministic<Sha256>>::default();
+
+        let sig_b = self.b.sign(tx_refund.digest());
+        let sig_a =
+            adaptor.decrypt_signature(&self.s_b.to_secpfun_scalar(), self.tx_refund_encsig.clone());
+
+        let signed_tx_refund =
+            tx_refund.add_signatures((self.A, sig_a), (self.b.public(), sig_b))?;
+
+        let (_, finality) = bitcoin_wallet.broadcast(signed_tx_refund, "refund").await?;
+
+        finality.await?;
+
+        Ok(())
+    }
+
+    pub fn tx_lock_id(&self) -> bitcoin::Txid {
+        self.tx_lock.txid()
+    }
+}

swap/src/protocol/bob/swap.rs

@@ -184,11 +184,11 @@ async fn run_until_internal(
                         BobState::EncSigSent(state)
                     },
                     _ = state.wait_for_cancel_timelock_to_expire(bitcoin_wallet.as_ref()) => {
-                        BobState::CancelTimelockExpired(state)
+                        BobState::CancelTimelockExpired(state.cancel())
                     }
                 }
             } else {
-                BobState::CancelTimelockExpired(state)
+                BobState::CancelTimelockExpired(state.cancel())
             }
         }
         BobState::EncSigSent(state) => {
@@ -198,11 +198,11 @@ async fn run_until_internal(
                         BobState::BtcRedeemed(state5?)
                     },
                     _ = state.wait_for_cancel_timelock_to_expire(bitcoin_wallet.as_ref()) => {
-                        BobState::CancelTimelockExpired(state)
+                        BobState::CancelTimelockExpired(state.cancel())
                     }
                 }
             } else {
-                BobState::CancelTimelockExpired(state)
+                BobState::CancelTimelockExpired(state.cancel())
             }
         }
         BobState::BtcRedeemed(state) => {