//! 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 chain::channelmonitor::{ChannelMonitor, ChannelMonitorUpdate, ChannelMonitorUpdateErr, MonitorEvent};
+use chain::channelmonitor::{ChannelMonitor, ChannelMonitorUpdate, MonitorEvent};
use chain::keysinterface::Sign;
-use chain::transaction::OutPoint;
+use chain::transaction::{OutPoint, TransactionData};
+
+use prelude::*;
pub mod chaininterface;
pub mod chainmonitor;
pub mod channelmonitor;
pub mod transaction;
pub mod keysinterface;
+pub(crate) mod onchaintx;
+pub(crate) mod package;
+
+/// The best known block as identified by its hash and height.
+#[derive(Clone, Copy, PartialEq)]
+pub struct BestBlock {
+ block_hash: BlockHash,
+ height: u32,
+}
+
+impl BestBlock {
+ /// Constructs a `BestBlock` that represents the genesis block at height 0 of the given
+ /// network.
+ pub fn from_genesis(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 }
+}
/// An error when accessing the chain via [`Access`].
#[derive(Clone)]
/// The `Access` trait defines behavior for accessing chain data and state, such as blocks and
/// UTXOs.
-pub trait Access: Send + Sync {
+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.
fn get_utxo(&self, genesis_hash: &BlockHash, short_channel_id: u64) -> Result<TxOut, AccessError>;
}
-/// The `Listen` trait is used to be notified of when blocks have been connected or disconnected
-/// from the chain.
+/// The `Listen` trait is used to notify when blocks have been connected or disconnected from the
+/// chain.
+///
+/// Useful when needing to replay chain data upon startup or as new chain events occur. Clients
+/// 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.
///
-/// Useful when needing to replay chain data upon startup or as new chain events occur.
+/// 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.
+///
+/// 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.
+///
+/// # 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.
+///
+/// # 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.
+/// - 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.
+///
+/// See individual method documentation for further details.
+///
+/// [`transactions_confirmed`]: Self::transactions_confirmed
+/// [`transaction_unconfirmed`]: Self::transaction_unconfirmed
+/// [`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.
+ ///
+ /// Should 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].
+ ///
+ /// May be called before or after [`best_block_updated`] for the corresponding block. However,
+ /// 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
+ /// [`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.
+ ///
+ /// 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`].
+ ///
+ /// [`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.
+ ///
+ /// Should be called when a new header is available but may be skipped for intermediary blocks
+ /// if they become available at the same time.
+ fn best_block_updated(&self, header: &BlockHeader, height: u32);
+
+ /// Returns transactions that should be monitored for reorganization out of the chain.
+ ///
+ /// 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.
+ ///
+ /// May be called to determine the subset of transactions that must still 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
+ /// given to [`transaction_unconfirmed`].
+ ///
+ /// [`transactions_confirmed`]: Self::transactions_confirmed
+ /// [`transaction_unconfirmed`]: Self::transaction_unconfirmed
+ fn get_relevant_txids(&self) -> Vec<Txid>;
+}
+
+/// An error enum representing a failure to persist a channel monitor update.
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub enum ChannelMonitorUpdateErr {
+ /// 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) that failed
+ /// have been successfully applied, a [`MonitorEvent::UpdateCompleted`] event should be returned
+ /// via [`Watch::release_pending_monitor_events`] which will then restore the channel to an
+ /// operational state.
+ ///
+ /// Note that a given ChannelManager will *never* re-generate a given ChannelMonitorUpdate. If
+ /// you return a TemporaryFailure you must ensure that it is written to disk safely before
+ /// writing out the latest ChannelManager state.
+ ///
+ /// Even when a channel has been "frozen" updates to the ChannelMonitor can continue to occur
+ /// (eg if an inbound HTLC which we forwarded was claimed upstream resulting in us attempting
+ /// to claim it on this channel) and those updates must be applied wherever they can be. At
+ /// least one such updated ChannelMonitor must be persisted otherwise PermanentFailure should
+ /// be returned to get things on-chain ASAP using only the in-memory copy. Obviously updates to
+ /// the channel which would invalidate previous ChannelMonitors are not made when a channel has
+ /// been "frozen".
+ ///
+ /// Note that even if updates made after TemporaryFailure succeed you must still provide a
+ /// [`MonitorEvent::UpdateCompleted`] to ensure you have the latest monitor and re-enable
+ /// normal channel operation. Note that this is normally generated through a call to
+ /// [`ChainMonitor::channel_monitor_updated`].
+ ///
+ /// Note that the update being processed here will not be replayed for you when you return a
+ /// [`MonitorEvent::UpdateCompleted`] event via [`Watch::release_pending_monitor_events`], so
+ /// you must store the update itself on your own local disk prior to returning a
+ /// TemporaryFailure. You may, of course, employ a journaling approach, storing only the
+ /// ChannelMonitorUpdate on disk without updating the monitor itself, replaying the journal at
+ /// reload-time.
+ ///
+ /// 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.
+ ///
+ /// [`ChainMonitor::channel_monitor_updated`]: chainmonitor::ChainMonitor::channel_monitor_updated
+ TemporaryFailure,
+ /// Used to indicate no further channel monitor updates will be allowed (eg we've moved on to a
+ /// different watchtower and cannot update with all watchtowers that were previously informed
+ /// of this channel).
+ ///
+ /// At reception of this error, ChannelManager will force-close the channel and return at
+ /// least a final ChannelMonitorUpdate::ChannelForceClosed which must be delivered to at
+ /// least one ChannelMonitor copy. Revocation secret MUST NOT be released and offchain channel
+ /// update must be rejected.
+ ///
+ /// This failure may also signal a failure to update the local persisted copy of one of
+ /// the channel monitor instance.
+ ///
+ /// Note that even when you fail a holder commitment transaction update, you must store the
+ /// update to ensure you can claim from it in case of a duplicate copy of this ChannelMonitor
+ /// broadcasts it (e.g distributed channel-monitor deployment)
+ ///
+ /// In case of distributed watchtowers deployment, the new version must be written to disk, as
+ /// state may have been stored but rejected due to a block forcing a commitment broadcast. This
+ /// storage is used to claim outputs of rejected state confirmed onchain by another watchtower,
+ /// lagging behind on block processing.
+ PermanentFailure,
+}
+
/// The `Watch` trait defines behavior for watching on-chain activity pertaining to channels as
/// blocks are connected and disconnected.
///
/// 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>: Send + Sync {
+/// [`PermanentFailure`]: ChannelMonitorUpdateErr::PermanentFailure
+pub trait Watch<ChannelSigner: Sign> {
/// 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
+ /// 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
/// [`ChannelMonitorUpdateErr`] for invariants around returning an error.
///
/// [`update_monitor`]: channelmonitor::ChannelMonitor::update_monitor
- /// [`ChannelMonitorUpdateErr`]: channelmonitor::ChannelMonitorUpdateErr
fn update_channel(&self, funding_txo: OutPoint, update: ChannelMonitorUpdate) -> Result<(), ChannelMonitorUpdateErr>;
/// Returns any monitor events since the last call. Subsequent calls must only return new
/// events.
+ ///
+ /// 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::UpdateCompleted`] here, see [`ChannelMonitorUpdateErr::TemporaryFailure`].
fn release_pending_monitor_events(&self) -> Vec<MonitorEvent>;
}
/// processed later. Then, in order to block until the data has been processed, any [`Watch`]
/// invocation that has called the `Filter` must return [`TemporaryFailure`].
///
-/// [`TemporaryFailure`]: channelmonitor::ChannelMonitorUpdateErr::TemporaryFailure
+/// [`TemporaryFailure`]: ChannelMonitorUpdateErr::TemporaryFailure
/// [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: Send + Sync {
+pub trait Filter {
/// Registers interest in a transaction with `txid` and having an output with `script_pubkey` as
/// a spending condition.
fn register_tx(&self, txid: &Txid, script_pubkey: &Script);
///
/// [`ChannelMonitor`]: channelmonitor::ChannelMonitor
/// [`ChannelMonitor::block_connected`]: channelmonitor::ChannelMonitor::block_connected
+#[derive(Clone, PartialEq, 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) {
projects / rust-lightning / blobdiff