use bitcoin::network::constants::Network;
use bitcoin::secp256k1::PublicKey;
-use chain::channelmonitor::{ChannelMonitor, ChannelMonitorUpdate, MonitorEvent};
-use chain::keysinterface::Sign;
-use chain::transaction::{OutPoint, TransactionData};
+use crate::chain::channelmonitor::{ChannelMonitor, ChannelMonitorUpdate, MonitorEvent};
+use crate::chain::keysinterface::WriteableEcdsaChannelSigner;
+use crate::chain::transaction::{OutPoint, TransactionData};
-use prelude::*;
+use crate::prelude::*;
pub mod chaininterface;
pub mod chainmonitor;
pub(crate) mod package;
/// The best known block as identified by its hash and height.
-#[derive(Clone, Copy, PartialEq)]
+#[derive(Clone, Copy, PartialEq, Eq)]
pub struct BestBlock {
block_hash: BlockHash,
height: u32,
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].
/// [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 will not be returned
+ /// 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.
///
/// 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 error enum representing a failure to persist a channel monitor update.
-#[derive(Clone, Copy, Debug, PartialEq)]
-pub enum ChannelMonitorUpdateErr {
+/// An enum representing the status of a channel monitor update persistence.
+#[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,
/// Used to indicate a temporary failure (eg connection to a watchtower or remote backup of
/// our state failed, but is expected to succeed at some point in the future).
///
/// Such a failure will "freeze" a channel, preventing us from revoking old states or
/// submitting new commitment transactions to the counterparty. Once the update(s) which failed
- /// have been successfully applied, a [`MonitorEvent::UpdateCompleted`] can be used to restore
- /// the channel to an operational state.
+ /// have been successfully applied, a [`MonitorEvent::Completed`] can be used to restore the
+ /// channel to an operational state.
///
/// Note that a given [`ChannelManager`] will *never* re-generate a [`ChannelMonitorUpdate`].
/// If you return this error you must ensure that it is written to disk safely before writing
/// 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::UpdateCompleted`] is provided, even if you return no error on a
- /// later monitor update for the same channel.
+ /// 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 ChannelMonitors and other local state are backed up in a
/// remote location (with local copies persisted immediately), it is anticipated that all
- /// updates will return TemporaryFailure until the remote copies could be updated.
+ /// updates will return [`InProgress`] until the remote copies could be updated.
///
- /// [`PermanentFailure`]: ChannelMonitorUpdateErr::PermanentFailure
+ /// [`PermanentFailure`]: ChannelMonitorUpdateStatus::PermanentFailure
+ /// [`InProgress`]: ChannelMonitorUpdateStatus::InProgress
/// [`ChannelManager`]: crate::ln::channelmanager::ChannelManager
- TemporaryFailure,
+ InProgress,
/// Used to indicate no further channel monitor updates will be allowed (likely a disk failure
/// or a remote copy of this [`ChannelMonitor`] is no longer reachable and thus not updatable).
///
/// storage is used to claim outputs of rejected state confirmed onchain by another watchtower,
/// lagging behind on block processing.
///
- /// [`PermanentFailure`]: ChannelMonitorUpdateErr::PermanentFailure
+ /// [`PermanentFailure`]: ChannelMonitorUpdateStatus::PermanentFailure
/// [`ChannelManager`]: crate::ln::channelmanager::ChannelManager
PermanentFailure,
}
/// 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
+/// funds in the channel. See [`ChannelMonitorUpdateStatus`] for more details about how to handle
/// multiple instances.
///
-/// [`PermanentFailure`]: ChannelMonitorUpdateErr::PermanentFailure
-pub trait Watch<ChannelSigner: Sign> {
+/// [`PermanentFailure`]: ChannelMonitorUpdateStatus::PermanentFailure
+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.
///
- /// Note: this interface MUST error with [`ChannelMonitorUpdateErr::PermanentFailure`] if
+ /// Note: this interface MUST error with [`ChannelMonitorUpdateStatus::PermanentFailure`] if
/// the given `funding_txo` has previously been registered via `watch_channel`.
///
/// [`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>) -> 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.
+ /// [`ChannelMonitorUpdateStatus`] for invariants around returning an error.
///
/// [`update_monitor`]: channelmonitor::ChannelMonitor::update_monitor
- fn update_channel(&self, funding_txo: OutPoint, update: ChannelMonitorUpdate) -> Result<(), ChannelMonitorUpdateErr>;
+ 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.
/// to disk.
///
/// For details on asynchronous [`ChannelMonitor`] updating and returning
- /// [`MonitorEvent::UpdateCompleted`] here, see [`ChannelMonitorUpdateErr::TemporaryFailure`].
+ /// [`MonitorEvent::Completed`] here, see [`ChannelMonitorUpdateStatus::InProgress`].
fn release_pending_monitor_events(&self) -> Vec<(OutPoint, Vec<MonitorEvent>, Option<PublicKey>)>;
}
/// 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`]: 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 {
///
/// [`ChannelMonitor`]: channelmonitor::ChannelMonitor
/// [`ChannelMonitor::block_connected`]: channelmonitor::ChannelMonitor::block_connected
-#[derive(Clone, PartialEq, Hash)]
+#[derive(Clone, PartialEq, Eq, Hash)]
pub struct WatchedOutput {
/// First block where the transaction output may have been spent.
pub block_hash: Option<BlockHash>,
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