//! Structs and traits which allow other parts of rust-lightning to interact with the blockchain.
+use bitcoin::blockdata::block::{Block, BlockHeader};
use bitcoin::blockdata::script::Script;
use bitcoin::blockdata::transaction::TxOut;
use bitcoin::hash_types::{BlockHash, Txid};
+use chain::channelmonitor::{ChannelMonitor, ChannelMonitorUpdate, ChannelMonitorUpdateErr, MonitorEvent};
+use chain::keysinterface::Sign;
use chain::transaction::OutPoint;
pub mod chaininterface;
+pub mod chainmonitor;
+pub mod channelmonitor;
pub mod transaction;
pub mod keysinterface;
+/// An error when accessing the chain via [`Access`].
+///
+/// [`Access`]: trait.Access.html
+#[derive(Clone)]
+pub enum AccessError {
+ /// The requested chain is unknown.
+ UnknownChain,
+
+ /// The requested transaction doesn't exist or hasn't confirmed.
+ UnknownTx,
+}
+
/// The `Access` trait defines behavior for accessing chain data and state, such as blocks and
/// UTXOs.
pub trait Access: Send + Sync {
fn get_utxo(&self, genesis_hash: &BlockHash, short_channel_id: u64) -> Result<TxOut, AccessError>;
}
-/// An error when accessing the chain via [`Access`].
+/// The `Listen` trait is used to be notified of when blocks have been connected or disconnected
+/// from the chain.
///
-/// [`Access`]: trait.Access.html
-#[derive(Clone)]
-pub enum AccessError {
- /// The requested chain is unknown.
- UnknownChain,
+/// Useful when needing to replay chain data upon startup or as new chain events occur.
+pub trait Listen {
+ /// Notifies the listener that a block was added at the given height.
+ fn block_connected(&self, block: &Block, height: u32);
- /// The requested transaction doesn't exist or hasn't confirmed.
- UnknownTx,
+ /// Notifies the listener that a block was removed at the given height.
+ fn block_disconnected(&self, header: &BlockHeader, height: u32);
}
-/// An interface for providing [`WatchEvent`]s.
+/// 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.
///
-/// [`WatchEvent`]: enum.WatchEvent.html
-pub trait WatchEventProvider {
- /// Releases events produced since the last call. Subsequent calls must only return new events.
- fn release_pending_watch_events(&self) -> Vec<WatchEvent>;
+/// 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/struct.ChannelMonitor.html
+/// [`ChannelMonitorUpdateErr`]: channelmonitor/enum.ChannelMonitorUpdateErr.html
+/// [`PermanentFailure`]: channelmonitor/enum.ChannelMonitorUpdateErr.html#variant.PermanentFailure
+pub trait Watch<ChannelSigner: Sign>: Send + Sync {
+ /// 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.
+ ///
+ /// [`get_outputs_to_watch`]: channelmonitor/struct.ChannelMonitor.html#method.get_outputs_to_watch
+ /// [`block_connected`]: channelmonitor/struct.ChannelMonitor.html#method.block_connected
+ /// [`block_disconnected`]: channelmonitor/struct.ChannelMonitor.html#method.block_disconnected
+ fn watch_channel(&self, funding_txo: OutPoint, monitor: ChannelMonitor<ChannelSigner>) -> Result<(), ChannelMonitorUpdateErr>;
+
+ /// 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.
+ ///
+ /// [`update_monitor`]: channelmonitor/struct.ChannelMonitor.html#method.update_monitor
+ /// [`ChannelMonitorUpdateErr`]: channelmonitor/enum.ChannelMonitorUpdateErr.html
+ 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.
+ fn release_pending_monitor_events(&self) -> Vec<MonitorEvent>;
}
-/// An event indicating on-chain activity to watch for pertaining to a channel.
-pub enum WatchEvent {
- /// Watch for a transaction with `txid` and having an output with `script_pubkey` as a spending
- /// condition.
- WatchTransaction {
- /// Identifier of the transaction.
- txid: Txid,
-
- /// Spending condition for an output of the transaction.
- script_pubkey: Script,
- },
- /// Watch for spends of a transaction output identified by `outpoint` having `script_pubkey` as
- /// the spending condition.
- WatchOutput {
- /// Identifier for the output.
- outpoint: OutPoint,
-
- /// Spending condition for the output.
- script_pubkey: Script,
+/// The `Filter` trait defines behavior for indicating chain activity of interest pertaining to
+/// channels.
+///
+/// This is useful in order to have a [`Watch`] implementation convey to a chain source which
+/// transactions to be notified of. Notification may take the form of pre-filtering blocks or, in
+/// the case of [BIP 157]/[BIP 158], only fetching a block if the compact filter matches. If
+/// receiving full blocks from a chain source, any further filtering is unnecessary.
+///
+/// After an output has been registered, subsequent block retrievals from the chain source must not
+/// exclude any transactions matching the new criteria nor any in-block descendants of such
+/// transactions.
+///
+/// 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`].
+///
+/// [`Watch`]: trait.Watch.html
+/// [`TemporaryFailure`]: channelmonitor/enum.ChannelMonitorUpdateErr.html#variant.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 {
+ /// 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);
+
+ /// Registers interest in spends of a transaction output identified by `outpoint` having
+ /// `script_pubkey` as the spending condition.
+ fn register_output(&self, outpoint: &OutPoint, 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);
+ }
+
+ fn block_disconnected(&self, header: &BlockHeader, height: u32) {
+ (**self).block_disconnected(header, height);
+ }
+}
+
+impl<T: std::ops::Deref, U: std::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 block_disconnected(&self, header: &BlockHeader, height: u32) {
+ self.0.block_disconnected(header, height);
+ self.1.block_disconnected(header, height);
}
}
projects / rust-lightning / blobdiff