fix (Bob): Check if Bitcoin redeem transaction was published before transitioning to CancelTimelockExpired (#1427)

* fix (Bob): Check if Bitcoin redeem transaction was published before transitioning to CancelTimelockExpired

---------

Co-authored-by: binarybaron <86064887+binarybaron@users.noreply.github.com>
Co-authored-by: Byron Hambly <bhambly@blockstream.com>
This commit is contained in:
pokkst 2024-06-04 05:49:15 -05:00 committed by GitHub
parent 1930540c1f
commit 9635c0b551
No known key found for this signature in database
GPG Key ID: B5690EEEBB952194
5 changed files with 84 additions and 0 deletions

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@ -164,6 +164,7 @@ jobs:
ensure_same_swap_id, ensure_same_swap_id,
concurrent_bobs_before_xmr_lock_proof_sent, concurrent_bobs_before_xmr_lock_proof_sent,
alice_manually_redeems_after_enc_sig_learned, alice_manually_redeems_after_enc_sig_learned,
happy_path_bob_offline_while_alice_redeems_btc,
] ]
runs-on: ubuntu-latest runs-on: ubuntu-latest
steps: steps:

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@ -489,6 +489,27 @@ pub struct State4 {
} }
impl State4 { impl State4 {
pub async fn check_for_tx_redeem(&self, bitcoin_wallet: &bitcoin::Wallet) -> Result<State5> {
let tx_redeem =
bitcoin::TxRedeem::new(&self.tx_lock, &self.redeem_address, self.tx_redeem_fee);
let tx_redeem_encsig = self.b.encsign(self.S_a_bitcoin, tx_redeem.digest());
let tx_redeem_candidate = bitcoin_wallet.get_raw_transaction(tx_redeem.txid()).await?;
let tx_redeem_sig =
tx_redeem.extract_signature_by_key(tx_redeem_candidate, self.b.public())?;
let s_a = bitcoin::recover(self.S_a_bitcoin, tx_redeem_sig, tx_redeem_encsig)?;
let s_a = monero::private_key_from_secp256k1_scalar(s_a.into());
Ok(State5 {
s_a,
s_b: self.s_b,
v: self.v,
tx_lock: self.tx_lock.clone(),
monero_wallet_restore_blockheight: self.monero_wallet_restore_blockheight,
})
}
pub fn tx_redeem_encsig(&self) -> bitcoin::EncryptedSignature { pub fn tx_redeem_encsig(&self) -> bitcoin::EncryptedSignature {
let tx_redeem = let tx_redeem =
bitcoin::TxRedeem::new(&self.tx_lock, &self.redeem_address, self.tx_redeem_fee); bitcoin::TxRedeem::new(&self.tx_lock, &self.redeem_address, self.tx_redeem_fee);

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@ -183,6 +183,13 @@ async fn next_state(
} }
} }
BobState::XmrLocked(state) => { BobState::XmrLocked(state) => {
// In case we send the encrypted signature to Alice, but she doesn't give us a confirmation
// We need to check if she still published the Bitcoin redeem transaction
// Otherwise we risk staying stuck in "XmrLocked"
if let Ok(state5) = state.check_for_tx_redeem(bitcoin_wallet).await {
return Ok(BobState::BtcRedeemed(state5));
}
let tx_lock_status = bitcoin_wallet.subscribe_to(state.tx_lock.clone()).await; let tx_lock_status = bitcoin_wallet.subscribe_to(state.tx_lock.clone()).await;
if let ExpiredTimelocks::None { .. } = state.expired_timelock(bitcoin_wallet).await? { if let ExpiredTimelocks::None { .. } = state.expired_timelock(bitcoin_wallet).await? {
@ -207,6 +214,13 @@ async fn next_state(
} }
} }
BobState::EncSigSent(state) => { BobState::EncSigSent(state) => {
// We need to make sure that Alice did not publish the redeem transaction while we were offline
// Even if the cancel timelock expired, if Alice published the redeem transaction while we were away we cannot miss it
// If we do we cannot refund and will never be able to leave the "CancelTimelockExpired" state
if let Ok(state5) = state.check_for_tx_redeem(bitcoin_wallet).await {
return Ok(BobState::BtcRedeemed(state5));
}
let tx_lock_status = bitcoin_wallet.subscribe_to(state.tx_lock.clone()).await; let tx_lock_status = bitcoin_wallet.subscribe_to(state.tx_lock.clone()).await;
if let ExpiredTimelocks::None { .. } = state.expired_timelock(bitcoin_wallet).await? { if let ExpiredTimelocks::None { .. } = state.expired_timelock(bitcoin_wallet).await? {

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@ -0,0 +1,44 @@
pub mod harness;
use crate::harness::bob_run_until::is_encsig_sent;
use swap::asb::FixedRate;
use swap::protocol::bob::BobState;
use swap::protocol::{alice, bob};
use tokio::join;
#[tokio::test]
async fn given_bob_restarts_while_alice_redeems_btc() {
harness::setup_test(harness::SlowCancelConfig, |mut ctx| async move {
let (bob_swap, bob_handle) = ctx.bob_swap().await;
let swap_id = bob_swap.id;
let bob_swap = tokio::spawn(bob::run_until(bob_swap, is_encsig_sent));
let alice_swap = ctx.alice_next_swap().await;
let alice_swap = tokio::spawn(alice::run(alice_swap, FixedRate::default()));
let (bob_state, alice_state) = join!(bob_swap, alice_swap);
ctx.assert_alice_redeemed(alice_state??).await;
assert!(matches!(bob_state??, BobState::EncSigSent { .. }));
let (bob_swap, _) = ctx.stop_and_resume_bob_from_db(bob_handle, swap_id).await;
if let BobState::EncSigSent(state4) = bob_swap.state.clone() {
bob_swap
.bitcoin_wallet
.subscribe_to(state4.tx_lock)
.await
.wait_until_confirmed_with(state4.cancel_timelock)
.await?;
} else {
panic!("Bob in unexpected state {}", bob_swap.state);
}
// Restart Bob
let bob_state = bob::run(bob_swap).await?;
ctx.assert_bob_redeemed(bob_state).await;
Ok(())
})
.await;
}

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@ -996,6 +996,10 @@ pub mod alice_run_until {
pub fn is_encsig_learned(state: &AliceState) -> bool { pub fn is_encsig_learned(state: &AliceState) -> bool {
matches!(state, AliceState::EncSigLearned { .. }) matches!(state, AliceState::EncSigLearned { .. })
} }
pub fn is_btc_redeemed(state: &AliceState) -> bool {
matches!(state, AliceState::BtcRedeemed { .. })
}
} }
pub mod bob_run_until { pub mod bob_run_until {