//! Structs and traits which allow other parts of rust-lightning to interact with the blockchain.
use bitcoin::blockdata::block::{Block, BlockHeader};
+use bitcoin::blockdata::constants::genesis_block;
use bitcoin::blockdata::script::Script;
-use bitcoin::blockdata::transaction::{Transaction, TxOut};
use bitcoin::hash_types::{BlockHash, Txid};
+use bitcoin::network::constants::Network;
+use bitcoin::secp256k1::PublicKey;
-use chain::channelmonitor::{ChannelMonitor, ChannelMonitorUpdate, ChannelMonitorUpdateErr, MonitorEvent};
-use chain::keysinterface::Sign;
-use chain::transaction::{OutPoint, TransactionData};
+use crate::chain::channelmonitor::{ChannelMonitor, ChannelMonitorUpdate, MonitorEvent};
+use crate::sign::WriteableEcdsaChannelSigner;
+use crate::chain::transaction::{OutPoint, TransactionData};
+
+use crate::prelude::*;
pub mod chaininterface;
pub mod chainmonitor;
pub mod channelmonitor;
pub mod transaction;
-pub mod keysinterface;
-
-/// An error when accessing the chain via [`Access`].
-#[derive(Clone)]
-pub enum AccessError {
- /// The requested chain is unknown.
- UnknownChain,
+pub(crate) mod onchaintx;
+pub(crate) mod package;
- /// The requested transaction doesn't exist or hasn't confirmed.
- UnknownTx,
+/// The best known block as identified by its hash and height.
+#[derive(Clone, Copy, PartialEq, Eq)]
+pub struct BestBlock {
+ block_hash: BlockHash,
+ height: u32,
}
-/// The `Access` trait defines behavior for accessing chain data and state, such as blocks and
-/// UTXOs.
-pub trait Access {
- /// Returns the transaction output of a funding transaction encoded by [`short_channel_id`].
- /// Returns an error if `genesis_hash` is for a different chain or if such a transaction output
- /// is unknown.
- ///
- /// [`short_channel_id`]: https://github.com/lightningnetwork/lightning-rfc/blob/master/07-routing-gossip.md#definition-of-short_channel_id
- fn get_utxo(&self, genesis_hash: &BlockHash, short_channel_id: u64) -> Result<TxOut, AccessError>;
+impl BestBlock {
+ /// Constructs a `BestBlock` that represents the genesis block at height 0 of the given
+ /// network.
+ pub fn from_network(network: Network) -> Self {
+ BestBlock {
+ block_hash: genesis_block(network).header.block_hash(),
+ height: 0,
+ }
+ }
+
+ /// Returns a `BestBlock` as identified by the given block hash and height.
+ pub fn new(block_hash: BlockHash, height: u32) -> Self {
+ BestBlock { block_hash, height }
+ }
+
+ /// Returns the best block hash.
+ pub fn block_hash(&self) -> BlockHash { self.block_hash }
+
+ /// Returns the best block height.
+ pub fn height(&self) -> u32 { self.height }
}
+
/// The `Listen` trait is used to notify when blocks have been connected or disconnected from the
/// chain.
///
/// sourcing chain data using a block-oriented API should prefer this interface over [`Confirm`].
/// Such clients fetch the entire header chain whereas clients using [`Confirm`] only fetch headers
/// when needed.
+///
+/// By using [`Listen::filtered_block_connected`] this interface supports clients fetching the
+/// entire header chain and only blocks with matching transaction data using BIP 157 filters or
+/// other similar filtering.
pub trait Listen {
+ /// Notifies the listener that a block was added at the given height, with the transaction data
+ /// possibly filtered.
+ fn filtered_block_connected(&self, header: &BlockHeader, txdata: &TransactionData, height: u32);
+
/// Notifies the listener that a block was added at the given height.
- fn block_connected(&self, block: &Block, height: u32);
+ fn block_connected(&self, block: &Block, height: u32) {
+ let txdata: Vec<_> = block.txdata.iter().enumerate().collect();
+ self.filtered_block_connected(&block.header, &txdata, height);
+ }
/// Notifies the listener that a block was removed at the given height.
fn block_disconnected(&self, header: &BlockHeader, height: u32);
}
-/// The `Confirm` trait is used to notify when transactions have been confirmed on chain or
-/// unconfirmed during a chain reorganization.
+/// The `Confirm` trait is used to notify LDK when relevant transactions have been confirmed on
+/// chain or unconfirmed during a chain reorganization.
///
/// Clients sourcing chain data using a transaction-oriented API should prefer this interface over
-/// [`Listen`]. For instance, an Electrum client may implement [`Filter`] by subscribing to activity
-/// related to registered transactions and outputs. Upon notification, it would pass along the
-/// matching transactions using this interface.
+/// [`Listen`]. For instance, an Electrum-based transaction sync implementation may implement
+/// [`Filter`] to subscribe to relevant transactions and unspent outputs it should monitor for
+/// on-chain activity. Then, it needs to notify LDK via this interface upon observing any changes
+/// with reference to the confirmation status of the monitored objects.
///
/// # Use
-///
/// The intended use is as follows:
-/// - Call [`transactions_confirmed`] to process any on-chain activity of interest.
-/// - Call [`transaction_unconfirmed`] to process any transaction returned by [`get_relevant_txids`]
-/// that has been reorganized out of the chain.
-/// - Call [`best_block_updated`] whenever a new chain tip becomes available.
+/// - Call [`transactions_confirmed`] to notify LDK whenever any of the registered transactions or
+/// outputs are, respectively, confirmed or spent on chain.
+/// - Call [`transaction_unconfirmed`] to notify LDK whenever any transaction returned by
+/// [`get_relevant_txids`] is no longer confirmed in the block with the given block hash.
+/// - Call [`best_block_updated`] to notify LDK whenever a new chain tip becomes available.
///
/// # Order
///
/// Clients must call these methods in chain order. Specifically:
-/// - Transactions confirmed in a block must be given before transactions confirmed in a later
-/// block.
+/// - Transactions which are confirmed in a particular block must be given before transactions
+/// confirmed in a later block.
/// - Dependent transactions within the same block must be given in topological order, possibly in
/// separate calls.
-/// - Unconfirmed transactions must be given after the original confirmations and before any
-/// reconfirmation.
+/// - All unconfirmed transactions must be given after the original confirmations and before *any*
+/// reconfirmations, i.e., [`transactions_confirmed`] and [`transaction_unconfirmed`] calls should
+/// never be interleaved, but always conduced *en bloc*.
+/// - Any reconfirmed transactions need to be explicitly unconfirmed before they are reconfirmed
+/// in regard to the new block.
///
/// See individual method documentation for further details.
///
/// [`best_block_updated`]: Self::best_block_updated
/// [`get_relevant_txids`]: Self::get_relevant_txids
pub trait Confirm {
- /// Processes transactions confirmed in a block with a given header and height.
+ /// Notifies LDK of transactions confirmed in a block with a given header and height.
///
- /// Should be called for any transactions registered by [`Filter::register_tx`] or any
+ /// Must be called for any transactions registered by [`Filter::register_tx`] or any
/// transactions spending an output registered by [`Filter::register_output`]. Such transactions
/// appearing in the same block do not need to be included in the same call; instead, multiple
/// calls with additional transactions may be made so long as they are made in [chain order].
/// in the event of a chain reorganization, it must not be called with a `header` that is no
/// longer in the chain as of the last call to [`best_block_updated`].
///
- /// [chain order]: Confirm#Order
+ /// [chain order]: Confirm#order
/// [`best_block_updated`]: Self::best_block_updated
fn transactions_confirmed(&self, header: &BlockHeader, txdata: &TransactionData, height: u32);
-
- /// Processes a transaction that is no longer confirmed as result of a chain reorganization.
+ /// Notifies LDK of a transaction that is no longer confirmed as result of a chain reorganization.
///
- /// Should be called for any transaction returned by [`get_relevant_txids`] if it has been
- /// reorganized out of the best chain. Once called, the given transaction should not be returned
- /// by [`get_relevant_txids`] unless it has been reconfirmed via [`transactions_confirmed`].
+ /// Must be called for any transaction returned by [`get_relevant_txids`] if it has been
+ /// reorganized out of the best chain or if it is no longer confirmed in the block with the
+ /// given block hash. Once called, the given transaction will not be returned
+ /// by [`get_relevant_txids`], unless it has been reconfirmed via [`transactions_confirmed`].
///
/// [`get_relevant_txids`]: Self::get_relevant_txids
/// [`transactions_confirmed`]: Self::transactions_confirmed
fn transaction_unconfirmed(&self, txid: &Txid);
-
- /// Processes an update to the best header connected at the given height.
+ /// Notifies LDK of an update to the best header connected at the given height.
///
- /// Should be called when a new header is available but may be skipped for intermediary blocks
- /// if they become available at the same time.
+ /// Must be called whenever a new chain tip becomes available. May be skipped for intermediary
+ /// blocks.
fn best_block_updated(&self, header: &BlockHeader, height: u32);
-
- /// Returns transactions that should be monitored for reorganization out of the chain.
+ /// Returns transactions that must be monitored for reorganization out of the chain along
+ /// with the hash of the block as part of which it had been previously confirmed.
+ ///
+ /// Note that the returned `Option<BlockHash>` might be `None` for channels created with LDK
+ /// 0.0.112 and prior, in which case you need to manually track previous confirmations.
///
- /// Should include any transactions passed to [`transactions_confirmed`] that have insufficient
- /// confirmations to be safe from a chain reorganization. Should not include any transactions
- /// passed to [`transaction_unconfirmed`] unless later reconfirmed.
+ /// Will include any transactions passed to [`transactions_confirmed`] that have insufficient
+ /// confirmations to be safe from a chain reorganization. Will not include any transactions
+ /// passed to [`transaction_unconfirmed`], unless later reconfirmed.
///
- /// May be called to determine the subset of transactions that must still be monitored for
+ /// Must be called to determine the subset of transactions that must be monitored for
/// reorganization. Will be idempotent between calls but may change as a result of calls to the
- /// other interface methods. Thus, this is useful to determine which transactions may need to be
+ /// other interface methods. Thus, this is useful to determine which transactions must be
/// given to [`transaction_unconfirmed`].
///
+ /// If any of the returned transactions are confirmed in a block other than the one with the
+ /// given hash, they need to be unconfirmed and reconfirmed via [`transaction_unconfirmed`] and
+ /// [`transactions_confirmed`], respectively.
+ ///
/// [`transactions_confirmed`]: Self::transactions_confirmed
/// [`transaction_unconfirmed`]: Self::transaction_unconfirmed
- fn get_relevant_txids(&self) -> Vec<Txid>;
+ fn get_relevant_txids(&self) -> Vec<(Txid, Option<BlockHash>)>;
+}
+
+/// An enum representing the status of a channel monitor update persistence.
+///
+/// These are generally used as the return value for an implementation of [`Persist`] which is used
+/// as the storage layer for a [`ChainMonitor`]. See the docs on [`Persist`] for a high-level
+/// explanation of how to handle different cases.
+///
+/// While `UnrecoverableError` is provided as a failure variant, it is not truly "handled" on the
+/// calling side, and generally results in an immediate panic. For those who prefer to avoid
+/// panics, `InProgress` can be used and you can retry the update operation in the background or
+/// shut down cleanly.
+///
+/// Note that channels should generally *not* be force-closed after a persistence failure.
+/// Force-closing with the latest [`ChannelMonitorUpdate`] applied may result in a transaction
+/// being broadcast which can only be spent by the latest [`ChannelMonitor`]! Thus, if the
+/// latest [`ChannelMonitor`] is not durably persisted anywhere and exists only in memory, naively
+/// calling [`ChannelManager::force_close_broadcasting_latest_txn`] *may result in loss of funds*!
+///
+/// [`Persist`]: chainmonitor::Persist
+/// [`ChainMonitor`]: chainmonitor::ChainMonitor
+/// [`ChannelManager::force_close_broadcasting_latest_txn`]: crate::ln::channelmanager::ChannelManager::force_close_broadcasting_latest_txn
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub enum ChannelMonitorUpdateStatus {
+ /// The update has been durably persisted and all copies of the relevant [`ChannelMonitor`]
+ /// have been updated.
+ ///
+ /// This includes performing any `fsync()` calls required to ensure the update is guaranteed to
+ /// be available on restart even if the application crashes.
+ Completed,
+ /// Indicates that the update will happen asynchronously in the background or that a transient
+ /// failure occurred which is being retried in the background and will eventually complete.
+ ///
+ /// This will "freeze" a channel, preventing us from revoking old states or submitting a new
+ /// commitment transaction to the counterparty. Once the update(s) which are `InProgress` have
+ /// been completed, a [`MonitorEvent::Completed`] can be used to restore the channel to an
+ /// operational state.
+ ///
+ /// Even when a channel has been "frozen", updates to the [`ChannelMonitor`] can continue to
+ /// occur (e.g. if an inbound HTLC which we forwarded was claimed upstream, resulting in us
+ /// attempting to claim it on this channel) and those updates must still be persisted.
+ ///
+ /// No updates to the channel will be made which could invalidate other [`ChannelMonitor`]s
+ /// until a [`MonitorEvent::Completed`] is provided, even if you return no error on a later
+ /// monitor update for the same channel.
+ ///
+ /// For deployments where a copy of [`ChannelMonitor`]s and other local state are backed up in
+ /// a remote location (with local copies persisted immediately), it is anticipated that all
+ /// updates will return [`InProgress`] until the remote copies could be updated.
+ ///
+ /// Note that while fully asynchronous persistence of [`ChannelMonitor`] data is generally
+ /// reliable, this feature is considered beta, and a handful of edge-cases remain. Until the
+ /// remaining cases are fixed, in rare cases, *using this feature may lead to funds loss*.
+ ///
+ /// [`InProgress`]: ChannelMonitorUpdateStatus::InProgress
+ InProgress,
+ /// Indicates that an update has failed and will not complete at any point in the future.
+ ///
+ /// Currently returning this variant will cause LDK to immediately panic to encourage immediate
+ /// shutdown. In the future this may be updated to disconnect peers and refuse to continue
+ /// normal operation without a panic.
+ ///
+ /// Applications which wish to perform an orderly shutdown after failure should consider
+ /// returning [`InProgress`] instead and simply shut down without ever marking the update
+ /// complete.
+ ///
+ /// [`InProgress`]: ChannelMonitorUpdateStatus::InProgress
+ UnrecoverableError,
}
/// The `Watch` trait defines behavior for watching on-chain activity pertaining to channels as
/// blocks are connected and disconnected.
///
/// Each channel is associated with a [`ChannelMonitor`]. Implementations of this trait are
-/// responsible for maintaining a set of monitors such that they can be updated accordingly as
-/// channel state changes and HTLCs are resolved. See method documentation for specific
-/// requirements.
-///
-/// Implementations **must** ensure that updates are successfully applied and persisted upon method
-/// completion. If an update fails with a [`PermanentFailure`], then it must immediately shut down
-/// without taking any further action such as persisting the current state.
+/// responsible for maintaining a set of monitors such that they can be updated as channel state
+/// changes. On each update, *all copies* of a [`ChannelMonitor`] must be updated and the update
+/// persisted to disk to ensure that the latest [`ChannelMonitor`] state can be reloaded if the
+/// application crashes.
///
-/// If an implementation maintains multiple instances of a channel's monitor (e.g., by storing
-/// backup copies), then it must ensure that updates are applied across all instances. Otherwise, it
-/// could result in a revoked transaction being broadcast, allowing the counterparty to claim all
-/// funds in the channel. See [`ChannelMonitorUpdateErr`] for more details about how to handle
-/// multiple instances.
-///
-/// [`ChannelMonitor`]: channelmonitor::ChannelMonitor
-/// [`ChannelMonitorUpdateErr`]: channelmonitor::ChannelMonitorUpdateErr
-/// [`PermanentFailure`]: channelmonitor::ChannelMonitorUpdateErr::PermanentFailure
-pub trait Watch<ChannelSigner: Sign> {
+/// See method documentation and [`ChannelMonitorUpdateStatus`] for specific requirements.
+pub trait Watch<ChannelSigner: WriteableEcdsaChannelSigner> {
/// Watches a channel identified by `funding_txo` using `monitor`.
///
/// Implementations are responsible for watching the chain for the funding transaction along
/// with any spends of outputs returned by [`get_outputs_to_watch`]. In practice, this means
/// calling [`block_connected`] and [`block_disconnected`] on the monitor.
///
+ /// A return of `Err(())` indicates that the channel should immediately be force-closed without
+ /// broadcasting the funding transaction.
+ ///
+ /// If the given `funding_txo` has previously been registered via `watch_channel`, `Err(())`
+ /// must be returned.
+ ///
/// [`get_outputs_to_watch`]: channelmonitor::ChannelMonitor::get_outputs_to_watch
/// [`block_connected`]: channelmonitor::ChannelMonitor::block_connected
/// [`block_disconnected`]: channelmonitor::ChannelMonitor::block_disconnected
- fn watch_channel(&self, funding_txo: OutPoint, monitor: ChannelMonitor<ChannelSigner>) -> Result<(), ChannelMonitorUpdateErr>;
+ fn watch_channel(&self, funding_txo: OutPoint, monitor: ChannelMonitor<ChannelSigner>) -> Result<ChannelMonitorUpdateStatus, ()>;
/// Updates a channel identified by `funding_txo` by applying `update` to its monitor.
///
- /// Implementations must call [`update_monitor`] with the given update. See
- /// [`ChannelMonitorUpdateErr`] for invariants around returning an error.
+ /// Implementations must call [`ChannelMonitor::update_monitor`] with the given update. This
+ /// may fail (returning an `Err(())`), in which case this should return
+ /// [`ChannelMonitorUpdateStatus::InProgress`] (and the update should never complete). This
+ /// generally implies the channel has been closed (either by the funding outpoint being spent
+ /// on-chain or the [`ChannelMonitor`] having decided to do so and broadcasted a transaction),
+ /// and the [`ChannelManager`] state will be updated once it sees the funding spend on-chain.
+ ///
+ /// In general, persistence failures should be retried after returning
+ /// [`ChannelMonitorUpdateStatus::InProgress`] and eventually complete. If a failure truly
+ /// cannot be retried, the node should shut down immediately after returning
+ /// [`ChannelMonitorUpdateStatus::UnrecoverableError`], see its documentation for more info.
///
- /// [`update_monitor`]: channelmonitor::ChannelMonitor::update_monitor
- /// [`ChannelMonitorUpdateErr`]: channelmonitor::ChannelMonitorUpdateErr
- fn update_channel(&self, funding_txo: OutPoint, update: ChannelMonitorUpdate) -> Result<(), ChannelMonitorUpdateErr>;
+ /// [`ChannelManager`]: crate::ln::channelmanager::ChannelManager
+ fn update_channel(&self, funding_txo: OutPoint, update: &ChannelMonitorUpdate) -> ChannelMonitorUpdateStatus;
/// Returns any monitor events since the last call. Subsequent calls must only return new
/// events.
- fn release_pending_monitor_events(&self) -> Vec<MonitorEvent>;
+ ///
+ /// Note that after any block- or transaction-connection calls to a [`ChannelMonitor`], no
+ /// further events may be returned here until the [`ChannelMonitor`] has been fully persisted
+ /// to disk.
+ ///
+ /// For details on asynchronous [`ChannelMonitor`] updating and returning
+ /// [`MonitorEvent::Completed`] here, see [`ChannelMonitorUpdateStatus::InProgress`].
+ fn release_pending_monitor_events(&self) -> Vec<(OutPoint, Vec<MonitorEvent>, Option<PublicKey>)>;
}
/// The `Filter` trait defines behavior for indicating chain activity of interest pertaining to
/// Note that use as part of a [`Watch`] implementation involves reentrancy. Therefore, the `Filter`
/// should not block on I/O. Implementations should instead queue the newly monitored data to be
/// processed later. Then, in order to block until the data has been processed, any [`Watch`]
-/// invocation that has called the `Filter` must return [`TemporaryFailure`].
+/// invocation that has called the `Filter` must return [`InProgress`].
///
-/// [`TemporaryFailure`]: channelmonitor::ChannelMonitorUpdateErr::TemporaryFailure
+/// [`InProgress`]: ChannelMonitorUpdateStatus::InProgress
/// [BIP 157]: https://github.com/bitcoin/bips/blob/master/bip-0157.mediawiki
/// [BIP 158]: https://github.com/bitcoin/bips/blob/master/bip-0158.mediawiki
pub trait Filter {
/// Registers interest in spends of a transaction output.
///
- /// Optionally, when `output.block_hash` is set, should return any transaction spending the
- /// output that is found in the corresponding block along with its index.
- ///
- /// This return value is useful for Electrum clients in order to supply in-block descendant
- /// transactions which otherwise were not included. This is not necessary for other clients if
- /// such descendant transactions were already included (e.g., when a BIP 157 client provides the
- /// full block).
- fn register_output(&self, output: WatchedOutput) -> Option<(usize, Transaction)>;
+ /// Note that this method might be called during processing of a new block. You therefore need
+ /// to ensure that also dependent output spents within an already connected block are correctly
+ /// handled, e.g., by re-scanning the block in question whenever new outputs have been
+ /// registered mid-processing.
+ fn register_output(&self, output: WatchedOutput);
}
/// A transaction output watched by a [`ChannelMonitor`] for spends on-chain.
///
/// Used to convey to a [`Filter`] such an output with a given spending condition. Any transaction
/// spending the output must be given to [`ChannelMonitor::block_connected`] either directly or via
-/// the return value of [`Filter::register_output`].
+/// [`Confirm::transactions_confirmed`].
///
/// If `block_hash` is `Some`, this indicates the output was created in the corresponding block and
/// may have been spent there. See [`Filter::register_output`] for details.
///
/// [`ChannelMonitor`]: channelmonitor::ChannelMonitor
/// [`ChannelMonitor::block_connected`]: channelmonitor::ChannelMonitor::block_connected
+#[derive(Clone, PartialEq, Eq, Hash)]
pub struct WatchedOutput {
/// First block where the transaction output may have been spent.
pub block_hash: Option<BlockHash>,
pub script_pubkey: Script,
}
-impl<T: Listen> Listen for std::ops::Deref<Target = T> {
- fn block_connected(&self, block: &Block, height: u32) {
- (**self).block_connected(block, height);
+impl<T: Listen> Listen for core::ops::Deref<Target = T> {
+ fn filtered_block_connected(&self, header: &BlockHeader, txdata: &TransactionData, height: u32) {
+ (**self).filtered_block_connected(header, txdata, height);
}
fn block_disconnected(&self, header: &BlockHeader, height: u32) {
}
}
-impl<T: std::ops::Deref, U: std::ops::Deref> Listen for (T, U)
+impl<T: core::ops::Deref, U: core::ops::Deref> Listen for (T, U)
where
T::Target: Listen,
U::Target: Listen,
{
- fn block_connected(&self, block: &Block, height: u32) {
- self.0.block_connected(block, height);
- self.1.block_connected(block, height);
+ fn filtered_block_connected(&self, header: &BlockHeader, txdata: &TransactionData, height: u32) {
+ self.0.filtered_block_connected(header, txdata, height);
+ self.1.filtered_block_connected(header, txdata, height);
}
fn block_disconnected(&self, header: &BlockHeader, height: u32) {
self.1.block_disconnected(header, height);
}
}
+
+/// A unique identifier to track each pending output claim within a [`ChannelMonitor`].
+///
+/// This is not exported to bindings users as we just use [u8; 32] directly.
+#[derive(Copy, Clone, Debug, Hash, PartialEq, Eq)]
+pub struct ClaimId(pub [u8; 32]);
projects / rust-lightning / blobdiff