X-Git-Url: http://git.bitcoin.ninja/index.cgi?a=blobdiff_plain;f=lightning%2Fsrc%2Fchain%2Fmod.rs;h=24eb09e7090b212ea9867aba9844ed6993c83735;hb=f53d13bcb8220b3ce39e51a4d20beb23b3930d1f;hp=1d51f262216d3620fb068908864db0c545f0f734;hpb=94bb0c9128c2635ea08ec089f79fab04880dedd0;p=rust-lightning diff --git a/lightning/src/chain/mod.rs b/lightning/src/chain/mod.rs index 1d51f262..24eb09e7 100644 --- a/lightning/src/chain/mod.rs +++ b/lightning/src/chain/mod.rs @@ -9,23 +9,57 @@ //! 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::TxOut; +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`]. -/// -/// [`Access`]: trait.Access.html #[derive(Clone)] pub enum AccessError { /// The requested chain is unknown. @@ -37,7 +71,7 @@ pub enum AccessError { /// 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. @@ -46,6 +80,177 @@ pub trait Access: Send + Sync { 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. +/// +/// 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) { + 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; +} + +/// 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. /// @@ -64,19 +269,20 @@ pub trait Access: Send + Sync { /// 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: Send + Sync { +/// [`PermanentFailure`]: 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/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 + /// 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 fn watch_channel(&self, funding_txo: OutPoint, monitor: ChannelMonitor) -> Result<(), ChannelMonitorUpdateErr>; /// Updates a channel identified by `funding_txo` by applying `update` to its monitor. @@ -84,12 +290,18 @@ pub trait Watch: Send + Sync { /// 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 + /// [`update_monitor`]: channelmonitor::ChannelMonitor::update_monitor 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; } @@ -107,19 +319,74 @@ pub trait Watch: Send + Sync { /// /// 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` +/// 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 +/// [`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); - /// 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); + /// 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 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) { + (**self).block_disconnected(header, height); + } +} + +impl Listen for (T, U) +where + T::Target: Listen, + U::Target: Listen, +{ + 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) { + self.0.block_disconnected(header, height); + self.1.block_disconnected(header, height); + } }