Merge pull request #42 from benthecarman/chain-access

Author: benthecarman

node-manager/src/chain.rs

@@ -0,0 +1,378 @@
+use bitcoin::{BlockHash, BlockHeader, Script, Transaction, Txid};
+
+use crate::error::MutinyError;
+use crate::wallet::MutinyWallet;
+use bdk::blockchain::Blockchain;
+use bdk_macros::maybe_await;
+use lightning::chain::chaininterface::{
+    BroadcasterInterface, ConfirmationTarget, FeeEstimator, FEERATE_FLOOR_SATS_PER_KW,
+};
+use lightning::chain::{Confirm, Filter, WatchedOutput};
+use log::error;
+use std::collections::HashSet;
+use std::sync::{Arc, Mutex};
+use wasm_bindgen_futures::spawn_local;
+
+pub struct MutinyChain {
+    wallet: Arc<MutinyWallet>,
+    // Transactions that were registered via the `Filter` interface and have to be processed.
+    queued_transactions: Mutex<HashSet<Txid>>,
+    // Transactions that were previously processed, but must not be forgotten yet.
+    watched_transactions: Mutex<HashSet<Txid>>,
+    // Outputs that were registered via the `Filter` interface and have to be processed.
+    queued_outputs: Mutex<HashSet<WatchedOutput>>,
+    // Outputs that were previously processed, but must not be forgotten yet.
+    watched_outputs: Mutex<HashSet<WatchedOutput>>,
+    // The tip hash observed during our last sync.
+    last_sync_hash: futures::lock::Mutex<Option<BlockHash>>,
+}
+
+impl MutinyChain {
+    pub(crate) fn new(wallet: Arc<MutinyWallet>) -> Self {
+        let watched_transactions = Mutex::new(HashSet::new());
+        let queued_transactions = Mutex::new(HashSet::new());
+        let watched_outputs = Mutex::new(HashSet::new());
+        let queued_outputs = Mutex::new(HashSet::new());
+        let last_sync_hash = futures::lock::Mutex::new(None);
+        Self {
+            wallet,
+            queued_transactions,
+            watched_transactions,
+            queued_outputs,
+            watched_outputs,
+            last_sync_hash,
+        }
+    }
+
+    /// Syncs the LDK wallet via the `Confirm` interface. We run in a loop until we completed a
+    /// full iteration without
+    pub(crate) async fn sync(
+        &self,
+        confirmables: Vec<&(dyn Confirm + Sync)>,
+    ) -> Result<(), MutinyError> {
+        // This lock makes sure we're syncing once at a time.
+        let mut locked_last_sync_hash = self.last_sync_hash.lock().await;
+
+        let client = &*self.wallet.blockchain;
+
+        let mut tip_hash = client.get_tip_hash().await?;
+
+        loop {
+            let registrations_are_pending = self.process_queues();
+            let tip_is_new = Some(tip_hash) != *locked_last_sync_hash;
+
+            // We loop until any registered transactions have been processed at least once, or the
+            // tip hasn't been updated during the last iteration.
+            if !registrations_are_pending && !tip_is_new {
+                // Nothing to do.
+                break;
+            } else {
+                // Update the known tip to the newest one.
+                if tip_is_new {
+                    // First check for any unconfirmed transactions and act on it immediately.
+                    self.sync_unconfirmed_transactions(&confirmables).await?;
+
+                    match self.sync_best_block_updated(&confirmables, &tip_hash).await {
+                        Ok(()) => {}
+                        Err(MutinyError::ChainAccessFailed) => {
+                            // Immediately restart syncing when we encounter any inconsistencies.
+                            continue;
+                        }
+                        Err(err) => {
+                            // (Semi-)permanent failure, retry later.
+                            return Err(err);
+                        }
+                    }
+                }
+
+                match self.get_confirmed_transactions().await {
+                    Ok((confirmed_txs, unconfirmed_registered_txs, unspent_registered_outputs)) => {
+                        // Double-check tip hash. If something changed, restart last-minute.
+                        tip_hash = client.get_tip_hash().await?;
+                        if Some(tip_hash) != *locked_last_sync_hash {
+                            continue;
+                        }
+
+                        self.sync_confirmed_transactions(
+                            &confirmables,
+                            confirmed_txs,
+                            unconfirmed_registered_txs,
+                            unspent_registered_outputs,
+                        );
+                    }
+                    Err(MutinyError::ChainAccessFailed) => {
+                        // Immediately restart syncing when we encounter any inconsistencies.
+                        continue;
+                    }
+                    Err(err) => {
+                        // (Semi-)permanent failure, retry later.
+                        return Err(err);
+                    }
+                }
+                *locked_last_sync_hash = Some(tip_hash);
+            }
+        }
+        Ok(())
+    }
+
+    // Processes the transaction and output queues, returns `true` if new items had been
+    // registered.
+    fn process_queues(&self) -> bool {
+        let mut pending_registrations = false;
+        {
+            let mut locked_queued_transactions = self.queued_transactions.lock().unwrap();
+            if !locked_queued_transactions.is_empty() {
+                let mut locked_watched_transactions = self.watched_transactions.lock().unwrap();
+                pending_registrations = true;
+
+                locked_watched_transactions.extend(locked_queued_transactions.iter());
+                *locked_queued_transactions = HashSet::new();
+            }
+        }
+        {
+            let mut locked_queued_outputs = self.queued_outputs.lock().unwrap();
+            if !locked_queued_outputs.is_empty() {
+                let mut locked_watched_outputs = self.watched_outputs.lock().unwrap();
+                pending_registrations = true;
+
+                locked_watched_outputs.extend(locked_queued_outputs.iter().cloned());
+                *locked_queued_outputs = HashSet::new();
+            }
+        }
+        pending_registrations
+    }
+
+    async fn sync_best_block_updated(
+        &self,
+        confirmables: &Vec<&(dyn Confirm + Sync)>,
+        tip_hash: &BlockHash,
+    ) -> Result<(), MutinyError> {
+        let client = &*self.wallet.blockchain;
+
+        // Inform the interface of the new block.
+        let tip_header = client.get_header_by_hash(tip_hash).await?;
+        let tip_status = client.get_block_status(tip_hash).await?;
+        if tip_status.in_best_chain {
+            if let Some(tip_height) = tip_status.height {
+                for c in confirmables {
+                    c.best_block_updated(&tip_header, tip_height);
+                }
+            }
+        } else {
+            return Err(MutinyError::ChainAccessFailed);
+        }
+        Ok(())
+    }
+
+    fn sync_confirmed_transactions(
+        &self,
+        confirmables: &Vec<&(dyn Confirm + Sync)>,
+        confirmed_txs: Vec<ConfirmedTx>,
+        unconfirmed_registered_txs: HashSet<Txid>,
+        unspent_registered_outputs: HashSet<WatchedOutput>,
+    ) {
+        for ctx in confirmed_txs {
+            for c in confirmables {
+                c.transactions_confirmed(
+                    &ctx.block_header,
+                    &[(ctx.pos, &ctx.tx)],
+                    ctx.block_height,
+                );
+            }
+        }
+
+        *self.watched_transactions.lock().unwrap() = unconfirmed_registered_txs;
+        *self.watched_outputs.lock().unwrap() = unspent_registered_outputs;
+    }
+
+    async fn get_confirmed_transactions(
+        &self,
+    ) -> Result<(Vec<ConfirmedTx>, HashSet<Txid>, HashSet<WatchedOutput>), MutinyError> {
+        let client = &*self.wallet.blockchain;
+
+        // First, check the confirmation status of registered transactions as well as the
+        // status of dependent transactions of registered outputs.
+
+        let mut confirmed_txs = Vec::new();
+
+        // Check in the current queue, as well as in registered transactions leftover from
+        // previous iterations.
+        let registered_txs = self.watched_transactions.lock().unwrap().clone();
+
+        // Remember all registered but unconfirmed transactions for future processing.
+        let mut unconfirmed_registered_txs = HashSet::new();
+
+        for txid in registered_txs {
+            if let Some(confirmed_tx) = self.get_confirmed_tx(&txid, None, None).await? {
+                confirmed_txs.push(confirmed_tx);
+            } else {
+                unconfirmed_registered_txs.insert(txid);
+            }
+        }
+
+        // Check all registered outputs for dependent spending transactions.
+        let registered_outputs = self.watched_outputs.lock().unwrap().clone();
+
+        // Remember all registered outputs that haven't been spent for future processing.
+        let mut unspent_registered_outputs = HashSet::new();
+
+        for output in registered_outputs {
+            if let Some(output_status) = client
+                .get_output_status(&output.outpoint.txid, output.outpoint.index as u64)
+                .await?
+            {
+                if let Some(spending_txid) = output_status.txid {
+                    if let Some(spending_tx_status) = output_status.status {
+                        if let Some(confirmed_tx) = self
+                            .get_confirmed_tx(
+                                &spending_txid,
+                                spending_tx_status.block_hash,
+                                spending_tx_status.block_height,
+                            )
+                            .await?
+                        {
+                            confirmed_txs.push(confirmed_tx);
+                            continue;
+                        }
+                    }
+                }
+            }
+            unspent_registered_outputs.insert(output);
+        }
+
+        // Sort all confirmed transactions first by block height, then by in-block
+        // position, and finally feed them to the interface in order.
+        confirmed_txs.sort_unstable_by(|tx1, tx2| {
+            tx1.block_height
+                .cmp(&tx2.block_height)
+                .then_with(|| tx1.pos.cmp(&tx2.pos))
+        });
+
+        Ok((
+            confirmed_txs,
+            unconfirmed_registered_txs,
+            unspent_registered_outputs,
+        ))
+    }
+
+    async fn get_confirmed_tx(
+        &self,
+        txid: &Txid,
+        expected_block_hash: Option<BlockHash>,
+        known_block_height: Option<u32>,
+    ) -> Result<Option<ConfirmedTx>, MutinyError> {
+        let client = &*self.wallet.blockchain;
+
+        if let Some(merkle_proof) = client.get_merkle_proof(txid).await? {
+            let block_hash = client.get_block_hash(merkle_proof.block_height).await?;
+            if let Some(expected_block_hash) = expected_block_hash {
+                if expected_block_hash != block_hash {
+                    return Err(MutinyError::ChainAccessFailed);
+                }
+            }
+
+            let block_header = client.get_header_by_hash(&block_hash).await?;
+
+            if let Some(tx) = client.get_tx(txid).await? {
+                // We can take a shortcut here if a previous call already gave us the height.
+                if let Some(block_height) = known_block_height {
+                    // if we have mismatched heights something probably went wrong
+                    if merkle_proof.block_height != block_height {
+                        return Err(MutinyError::ChainAccessFailed);
+                    }
+                    return Ok(Some(ConfirmedTx {
+                        tx,
+                        block_header,
+                        pos: merkle_proof.pos,
+                        block_height,
+                    }));
+                }
+
+                return Ok(Some(ConfirmedTx {
+                    tx,
+                    block_header,
+                    pos: merkle_proof.pos,
+                    block_height: merkle_proof.block_height,
+                }));
+            }
+        }
+        Ok(None)
+    }
+
+    async fn sync_unconfirmed_transactions(
+        &self,
+        confirmables: &Vec<&(dyn Confirm + Sync)>,
+    ) -> Result<(), MutinyError> {
+        let client = &*self.wallet.blockchain;
+        // Query the interface for relevant txids and check whether they are still
+        // in the best chain, mark them unconfirmed otherwise.
+
+        let relevant_txids = confirmables
+            .iter()
+            .flat_map(|c| c.get_relevant_txids())
+            .collect::<Vec<Txid>>();
+        for txid in relevant_txids {
+            match client.get_tx_status(&txid).await {
+                Ok(Some(status)) => {
+                    // Skip if the tx in question is still confirmed.
+                    if status.confirmed {
+                        continue;
+                    }
+                }
+                // if the tx no longer exists or errors, we should
+                // consider it unconfirmed
+                Ok(None) => (),
+                Err(_) => (),
+            }
+
+            for c in confirmables {
+                c.transaction_unconfirmed(&txid);
+            }
+        }
+
+        Ok(())
+    }
+}
+
+struct ConfirmedTx {
+    tx: Transaction,
+    block_header: BlockHeader,
+    block_height: u32,
+    pos: usize,
+}
+
+impl Filter for MutinyChain {
+    fn register_tx(&self, txid: &Txid, _script_pubkey: &Script) {
+        self.queued_transactions.lock().unwrap().insert(*txid);
+    }
+
+    fn register_output(&self, output: WatchedOutput) {
+        self.queued_outputs.lock().unwrap().insert(output);
+    }
+}
+
+impl BroadcasterInterface for MutinyChain {
+    fn broadcast_transaction(&self, tx: &Transaction) {
+        let blockchain = self.wallet.blockchain.clone();
+        let tx_clone = tx.clone();
+        spawn_local(async move {
+            maybe_await!(blockchain.broadcast(&tx_clone))
+                .unwrap_or_else(|_| error!("failed to broadcast tx! {}", tx_clone.txid()))
+        });
+    }
+}
+
+impl FeeEstimator for MutinyChain {
+    fn get_est_sat_per_1000_weight(&self, confirmation_target: ConfirmationTarget) -> u32 {
+        // todo get from esplora
+        fallback_fee_from_conf_target(confirmation_target)
+    }
+}
+
+fn fallback_fee_from_conf_target(confirmation_target: ConfirmationTarget) -> u32 {
+    match confirmation_target {
+        ConfirmationTarget::Background => FEERATE_FLOOR_SATS_PER_KW,
+        ConfirmationTarget::Normal => 2000,
+        ConfirmationTarget::HighPriority => 5000,
+    }
+}

node-manager/src/error.rs

@@ -1,3 +1,4 @@
+use bdk::esplora_client;
 use lightning::ln::peer_handler::PeerHandleError;
 use thiserror::Error;
 use wasm_bindgen::JsValue;
@@ -92,6 +93,14 @@ impl From<bdk::Error> for MutinyError {
     }
 }
 
+// TODO add more granular errors for esplora failures
+impl From<esplora_client::Error> for MutinyError {
+    fn from(_e: esplora_client::Error) -> Self {
+        // This is most likely a chain access failure
+        Self::ChainAccessFailed
+    }
+}
+
 impl From<PeerHandleError> for MutinyError {
     fn from(_e: PeerHandleError) -> Self {
         // TODO handle the case where `no_connection_possible`