X-Git-Url: http://git.bitcoin.ninja/index.cgi?a=blobdiff_plain;f=lightning%2Fsrc%2Fchain%2Fmod.rs;h=2e1eaea4e5f5b7d54c9828f4b6db769388f0ec89;hb=da298e498fc8bdf6af2b2becf82b0123118f46b4;hp=9968bc6c07284d13e556367a491571c1eec01a10;hpb=4395b92cc8bfe0cc803e70bba11f4db58d5d0dbf;p=rust-lightning diff --git a/lightning/src/chain/mod.rs b/lightning/src/chain/mod.rs index 9968bc6c..2e1eaea4 100644 --- a/lightning/src/chain/mod.rs +++ b/lightning/src/chain/mod.rs @@ -9,6 +9,300 @@ //! 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::keysinterface::Sign; +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 { + /// Returns the best block from the genesis of the given network. + pub fn from_genesis(network: Network) -> Self { + BestBlock { + block_hash: genesis_block(network).header.block_hash(), + height: 0, + } + } + + /// Returns the best block 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)] +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 { + /// 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 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. +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 `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; +} + +/// 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 { + /// 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 { + /// 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 +#[derive(Clone, PartialEq, Hash)] +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 core::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); + } +}