// This file is Copyright its original authors, visible in version control // history. // // This file is licensed under the Apache License, Version 2.0 or the MIT license // , at your option. // You may not use this file except in accordance with one or both of these // licenses. //! 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::{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`]. #[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 { /// 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; } /// The `Listen` trait is used to be notified of 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. pub trait Listen { /// Notifies the listener that a block was added at the given height. fn block_connected(&self, block: &Block, height: u32); /// Notifies the listener that a block was removed at the given height. fn block_disconnected(&self, header: &BlockHeader, height: u32); } /// 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. /// /// 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: 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::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) -> 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::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. fn release_pending_monitor_events(&self) -> Vec; } /// 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`]. /// /// [`TemporaryFailure`]: channelmonitor::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 { /// 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. /// /// 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)>; } /// 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`]. /// /// 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 pub struct WatchedOutput { /// First block where the transaction output may have been spent. pub block_hash: Option, /// Outpoint identifying the transaction output. pub outpoint: OutPoint, /// Spending condition of the transaction output. pub script_pubkey: Script, } impl Listen for std::ops::Deref { 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 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); } }