X-Git-Url: http://git.bitcoin.ninja/index.cgi?a=blobdiff_plain;f=lightning%2Fsrc%2Fchain%2Fchannelmonitor.rs;h=8be785f29d2c38c3165023816e8821b1853418d1;hb=0a31c12f85b55dd2b3a85e929a5c92086bc8842b;hp=761ad7bae83a84180075b39e1c0f4cf2a3dfd0b2;hpb=cd578b55f3650af2296f064f0cf9753f4cf85e93;p=rust-lightning diff --git a/lightning/src/chain/channelmonitor.rs b/lightning/src/chain/channelmonitor.rs index 761ad7ba..8be785f2 100644 --- a/lightning/src/chain/channelmonitor.rs +++ b/lightning/src/chain/channelmonitor.rs @@ -115,67 +115,6 @@ impl Readable for ChannelMonitorUpdate { } } -/// 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) which failed - /// have been successfully applied, ChannelManager::channel_monitor_updated can be used to - /// 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 call - /// channel_monitor_updated to ensure you have the latest monitor and re-enable normal channel - /// operation. - /// - /// Note that the update being processed here will not be replayed for you when you call - /// ChannelManager::channel_monitor_updated, so you must store the update itself along - /// with the persisted ChannelMonitor 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. - 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, -} - /// General Err type for ChannelMonitor actions. Generally, this implies that the data provided is /// inconsistent with the ChannelMonitor being called. eg for ChannelMonitor::update_monitor this /// means you tried to update a monitor for a different channel or the ChannelMonitorUpdate was @@ -190,9 +129,42 @@ pub enum MonitorEvent { /// A monitor event containing an HTLCUpdate. HTLCEvent(HTLCUpdate), - /// A monitor event that the Channel's commitment transaction was broadcasted. - CommitmentTxBroadcasted(OutPoint), + /// A monitor event that the Channel's commitment transaction was confirmed. + CommitmentTxConfirmed(OutPoint), + + /// Indicates a [`ChannelMonitor`] update has completed. See + /// [`ChannelMonitorUpdateErr::TemporaryFailure`] for more information on how this is used. + /// + /// [`ChannelMonitorUpdateErr::TemporaryFailure`]: super::ChannelMonitorUpdateErr::TemporaryFailure + UpdateCompleted { + /// The funding outpoint of the [`ChannelMonitor`] that was updated + funding_txo: OutPoint, + /// The Update ID from [`ChannelMonitorUpdate::update_id`] which was applied or + /// [`ChannelMonitor::get_latest_update_id`]. + /// + /// Note that this should only be set to a given update's ID if all previous updates for the + /// same [`ChannelMonitor`] have been applied and persisted. + monitor_update_id: u64, + }, + + /// Indicates a [`ChannelMonitor`] update has failed. See + /// [`ChannelMonitorUpdateErr::PermanentFailure`] for more information on how this is used. + /// + /// [`ChannelMonitorUpdateErr::PermanentFailure`]: super::ChannelMonitorUpdateErr::PermanentFailure + UpdateFailed(OutPoint), } +impl_writeable_tlv_based_enum_upgradable!(MonitorEvent, + // Note that UpdateCompleted and UpdateFailed are currently never serialized to disk as they are + // generated only in ChainMonitor + (0, UpdateCompleted) => { + (0, funding_txo, required), + (2, monitor_update_id, required), + }, +; + (2, HTLCEvent), + (4, CommitmentTxConfirmed), + (6, UpdateFailed), +); /// Simple structure sent back by `chain::Watch` when an HTLC from a forward channel is detected on /// chain. Used to update the corresponding HTLC in the backward channel. Failing to pass the @@ -232,8 +204,13 @@ pub(crate) const CLTV_CLAIM_BUFFER: u32 = 18; /// with at worst this delay, so we are not only using this value as a mercy for them but also /// us as a safeguard to delay with enough time. pub(crate) const LATENCY_GRACE_PERIOD_BLOCKS: u32 = 3; -/// Number of blocks we wait on seeing a HTLC output being solved before we fail corresponding inbound -/// HTLCs. This prevents us from failing backwards and then getting a reorg resulting in us losing money. +/// Number of blocks we wait on seeing a HTLC output being solved before we fail corresponding +/// inbound HTLCs. This prevents us from failing backwards and then getting a reorg resulting in us +/// losing money. +/// +/// Note that this is a library-wide security assumption. If a reorg deeper than this number of +/// blocks occurs, counterparties may be able to steal funds or claims made by and balances exposed +/// by a [`ChannelMonitor`] may be incorrect. // We also use this delay to be sure we can remove our in-flight claim txn from bump candidates buffer. // It may cause spurious generation of bumped claim txn but that's alright given the outpoint is already // solved by a previous claim tx. What we want to avoid is reorg evicting our claim tx and us not @@ -356,12 +333,21 @@ struct OnchainEventEntry { impl OnchainEventEntry { fn confirmation_threshold(&self) -> u32 { let mut conf_threshold = self.height + ANTI_REORG_DELAY - 1; - if let OnchainEvent::MaturingOutput { - descriptor: SpendableOutputDescriptor::DelayedPaymentOutput(ref descriptor) - } = self.event { - // A CSV'd transaction is confirmable in block (input height) + CSV delay, which means - // it's broadcastable when we see the previous block. - conf_threshold = cmp::max(conf_threshold, self.height + descriptor.to_self_delay as u32 - 1); + match self.event { + OnchainEvent::MaturingOutput { + descriptor: SpendableOutputDescriptor::DelayedPaymentOutput(ref descriptor) + } => { + // A CSV'd transaction is confirmable in block (input height) + CSV delay, which means + // it's broadcastable when we see the previous block. + conf_threshold = cmp::max(conf_threshold, self.height + descriptor.to_self_delay as u32 - 1); + }, + OnchainEvent::FundingSpendConfirmation { on_local_output_csv: Some(csv), .. } | + OnchainEvent::HTLCSpendConfirmation { on_to_local_output_csv: Some(csv), .. } => { + // A CSV'd transaction is confirmable in block (input height) + CSV delay, which means + // it's broadcastable when we see the previous block. + conf_threshold = cmp::max(conf_threshold, self.height + csv as u32 - 1); + }, + _ => {}, } conf_threshold } @@ -375,17 +361,47 @@ impl OnchainEventEntry { /// once they mature to enough confirmations (ANTI_REORG_DELAY) #[derive(PartialEq)] enum OnchainEvent { - /// HTLC output getting solved by a timeout, at maturation we pass upstream payment source information to solve - /// inbound HTLC in backward channel. Note, in case of preimage, we pass info to upstream without delay as we can - /// only win from it, so it's never an OnchainEvent + /// An outbound HTLC failing after a transaction is confirmed. Used + /// * when an outbound HTLC output is spent by us after the HTLC timed out + /// * an outbound HTLC which was not present in the commitment transaction which appeared + /// on-chain (either because it was not fully committed to or it was dust). + /// Note that this is *not* used for preimage claims, as those are passed upstream immediately, + /// appearing only as an `HTLCSpendConfirmation`, below. HTLCUpdate { source: HTLCSource, payment_hash: PaymentHash, onchain_value_satoshis: Option, + /// None in the second case, above, ie when there is no relevant output in the commitment + /// transaction which appeared on chain. + input_idx: Option, }, MaturingOutput { descriptor: SpendableOutputDescriptor, }, + /// A spend of the funding output, either a commitment transaction or a cooperative closing + /// transaction. + FundingSpendConfirmation { + /// The CSV delay for the output of the funding spend transaction (implying it is a local + /// commitment transaction, and this is the delay on the to_self output). + on_local_output_csv: Option, + }, + /// A spend of a commitment transaction HTLC output, set in the cases where *no* `HTLCUpdate` + /// is constructed. This is used when + /// * an outbound HTLC is claimed by our counterparty with a preimage, causing us to + /// immediately claim the HTLC on the inbound edge and track the resolution here, + /// * an inbound HTLC is claimed by our counterparty (with a timeout), + /// * an inbound HTLC is claimed by us (with a preimage). + /// * a revoked-state HTLC transaction was broadcasted, which was claimed by the revocation + /// signature. + HTLCSpendConfirmation { + input_idx: u32, + /// If the claim was made by either party with a preimage, this is filled in + preimage: Option, + /// If the claim was made by us on an inbound HTLC against a local commitment transaction, + /// we set this to the output CSV value which we will have to wait until to spend the + /// output (and generate a SpendableOutput event). + on_to_local_output_csv: Option, + }, } impl Writeable for OnchainEventEntry { @@ -422,10 +438,20 @@ impl_writeable_tlv_based_enum_upgradable!(OnchainEvent, (0, source, required), (1, onchain_value_satoshis, option), (2, payment_hash, required), + (3, input_idx, option), }, (1, MaturingOutput) => { (0, descriptor, required), }, + (3, FundingSpendConfirmation) => { + (0, on_local_output_csv, option), + }, + (5, HTLCSpendConfirmation) => { + (0, input_idx, required), + (2, preimage, option), + (4, on_to_local_output_csv, option), + }, + ); #[cfg_attr(any(test, feature = "fuzztarget", feature = "_test_utils"), derive(PartialEq))] @@ -486,6 +512,72 @@ impl_writeable_tlv_based_enum_upgradable!(ChannelMonitorUpdateStep, }, ); +/// Details about the balance(s) available for spending once the channel appears on chain. +/// +/// See [`ChannelMonitor::get_claimable_balances`] for more details on when these will or will not +/// be provided. +#[derive(Clone, Debug, PartialEq, Eq)] +#[cfg_attr(test, derive(PartialOrd, Ord))] +pub enum Balance { + /// The channel is not yet closed (or the commitment or closing transaction has not yet + /// appeared in a block). The given balance is claimable (less on-chain fees) if the channel is + /// force-closed now. + ClaimableOnChannelClose { + /// The amount available to claim, in satoshis, excluding the on-chain fees which will be + /// required to do so. + claimable_amount_satoshis: u64, + }, + /// The channel has been closed, and the given balance is ours but awaiting confirmations until + /// we consider it spendable. + ClaimableAwaitingConfirmations { + /// The amount available to claim, in satoshis, possibly excluding the on-chain fees which + /// were spent in broadcasting the transaction. + claimable_amount_satoshis: u64, + /// The height at which an [`Event::SpendableOutputs`] event will be generated for this + /// amount. + confirmation_height: u32, + }, + /// The channel has been closed, and the given balance should be ours but awaiting spending + /// transaction confirmation. If the spending transaction does not confirm in time, it is + /// possible our counterparty can take the funds by broadcasting an HTLC timeout on-chain. + /// + /// Once the spending transaction confirms, before it has reached enough confirmations to be + /// considered safe from chain reorganizations, the balance will instead be provided via + /// [`Balance::ClaimableAwaitingConfirmations`]. + ContentiousClaimable { + /// The amount available to claim, in satoshis, excluding the on-chain fees which will be + /// required to do so. + claimable_amount_satoshis: u64, + /// The height at which the counterparty may be able to claim the balance if we have not + /// done so. + timeout_height: u32, + }, + /// HTLCs which we sent to our counterparty which are claimable after a timeout (less on-chain + /// fees) if the counterparty does not know the preimage for the HTLCs. These are somewhat + /// likely to be claimed by our counterparty before we do. + MaybeClaimableHTLCAwaitingTimeout { + /// The amount available to claim, in satoshis, excluding the on-chain fees which will be + /// required to do so. + claimable_amount_satoshis: u64, + /// The height at which we will be able to claim the balance if our counterparty has not + /// done so. + claimable_height: u32, + }, +} + +/// An HTLC which has been irrevocably resolved on-chain, and has reached ANTI_REORG_DELAY. +#[derive(PartialEq)] +struct IrrevocablyResolvedHTLC { + input_idx: u32, + /// Only set if the HTLC claim was ours using a payment preimage + payment_preimage: Option, +} + +impl_writeable_tlv_based!(IrrevocablyResolvedHTLC, { + (0, input_idx, required), + (2, payment_preimage, option), +}); + /// A ChannelMonitor handles chain events (blocks connected and disconnected) and generates /// on-chain transactions to ensure no loss of funds occurs. /// @@ -565,7 +657,17 @@ pub(crate) struct ChannelMonitorImpl { payment_preimages: HashMap, + // Note that `MonitorEvent`s MUST NOT be generated during update processing, only generated + // during chain data processing. This prevents a race in `ChainMonitor::update_channel` (and + // presumably user implementations thereof as well) where we update the in-memory channel + // object, then before the persistence finishes (as it's all under a read-lock), we return + // pending events to the user or to the relevant `ChannelManager`. Then, on reload, we'll have + // the pre-event state here, but have processed the event in the `ChannelManager`. + // Note that because the `event_lock` in `ChainMonitor` is only taken in + // block/transaction-connected events and *not* during block/transaction-disconnected events, + // we further MUST NOT generate events during block/transaction-disconnection. pending_monitor_events: Vec, + pending_events: Vec, // Used to track on-chain events (i.e., transactions part of channels confirmed on chain) on @@ -598,6 +700,12 @@ pub(crate) struct ChannelMonitorImpl { // remote monitor out-of-order with regards to the block view. holder_tx_signed: bool, + funding_spend_confirmed: Option, + /// The set of HTLCs which have been either claimed or failed on chain and have reached + /// the requisite confirmations on the claim/fail transaction (either ANTI_REORG_DELAY or the + /// spending CSV for revocable outputs). + htlcs_resolved_on_chain: Vec, + // We simply modify best_block in Channel's block_connected so that serialization is // consistent but hopefully the users' copy handles block_connected in a consistent way. // (we do *not*, however, update them in update_monitor to ensure any local user copies keep @@ -656,7 +764,9 @@ impl PartialEq for ChannelMonitorImpl { self.onchain_events_awaiting_threshold_conf != other.onchain_events_awaiting_threshold_conf || self.outputs_to_watch != other.outputs_to_watch || self.lockdown_from_offchain != other.lockdown_from_offchain || - self.holder_tx_signed != other.holder_tx_signed + self.holder_tx_signed != other.holder_tx_signed || + self.funding_spend_confirmed != other.funding_spend_confirmed || + self.htlcs_resolved_on_chain != other.htlcs_resolved_on_chain { false } else { @@ -783,14 +893,19 @@ impl Writeable for ChannelMonitorImpl { writer.write_all(&payment_preimage.0[..])?; } - writer.write_all(&byte_utils::be64_to_array(self.pending_monitor_events.len() as u64))?; + writer.write_all(&(self.pending_monitor_events.iter().filter(|ev| match ev { + MonitorEvent::HTLCEvent(_) => true, + MonitorEvent::CommitmentTxConfirmed(_) => true, + _ => false, + }).count() as u64).to_be_bytes())?; for event in self.pending_monitor_events.iter() { match event { MonitorEvent::HTLCEvent(upd) => { 0u8.write(writer)?; upd.write(writer)?; }, - MonitorEvent::CommitmentTxBroadcasted(_) => 1u8.write(writer)? + MonitorEvent::CommitmentTxConfirmed(_) => 1u8.write(writer)?, + _ => {}, // Covered in the TLV writes below } } @@ -821,7 +936,11 @@ impl Writeable for ChannelMonitorImpl { self.lockdown_from_offchain.write(writer)?; self.holder_tx_signed.write(writer)?; - write_tlv_fields!(writer, {}); + write_tlv_fields!(writer, { + (1, self.funding_spend_confirmed, option), + (3, self.htlcs_resolved_on_chain, vec_type), + (5, self.pending_monitor_events, vec_type), + }); Ok(()) } @@ -919,6 +1038,8 @@ impl ChannelMonitor { lockdown_from_offchain: false, holder_tx_signed: false, + funding_spend_confirmed: None, + htlcs_resolved_on_chain: Vec::new(), best_block, @@ -1227,6 +1348,268 @@ impl ChannelMonitor { pub fn current_best_block(&self) -> BestBlock { self.inner.lock().unwrap().best_block.clone() } + + /// Gets the balances in this channel which are either claimable by us if we were to + /// force-close the channel now or which are claimable on-chain (possibly awaiting + /// confirmation). + /// + /// Any balances in the channel which are available on-chain (excluding on-chain fees) are + /// included here until an [`Event::SpendableOutputs`] event has been generated for the + /// balance, or until our counterparty has claimed the balance and accrued several + /// confirmations on the claim transaction. + /// + /// Note that the balances available when you or your counterparty have broadcasted revoked + /// state(s) may not be fully captured here. + // TODO, fix that ^ + /// + /// See [`Balance`] for additional details on the types of claimable balances which + /// may be returned here and their meanings. + pub fn get_claimable_balances(&self) -> Vec { + let mut res = Vec::new(); + let us = self.inner.lock().unwrap(); + + let mut confirmed_txid = us.funding_spend_confirmed; + let mut pending_commitment_tx_conf_thresh = None; + let funding_spend_pending = us.onchain_events_awaiting_threshold_conf.iter().find_map(|event| { + if let OnchainEvent::FundingSpendConfirmation { .. } = event.event { + Some((event.txid, event.confirmation_threshold())) + } else { None } + }); + if let Some((txid, conf_thresh)) = funding_spend_pending { + debug_assert!(us.funding_spend_confirmed.is_none(), + "We have a pending funding spend awaiting anti-reorg confirmation, we can't have confirmed it already!"); + confirmed_txid = Some(txid); + pending_commitment_tx_conf_thresh = Some(conf_thresh); + } + + macro_rules! walk_htlcs { + ($holder_commitment: expr, $htlc_iter: expr) => { + for htlc in $htlc_iter { + if let Some(htlc_input_idx) = htlc.transaction_output_index { + if us.htlcs_resolved_on_chain.iter().any(|v| v.input_idx == htlc_input_idx) { + assert!(us.funding_spend_confirmed.is_some()); + } else if htlc.offered == $holder_commitment { + // If the payment was outbound, check if there's an HTLCUpdate + // indicating we have spent this HTLC with a timeout, claiming it back + // and awaiting confirmations on it. + let htlc_update_pending = us.onchain_events_awaiting_threshold_conf.iter().find_map(|event| { + if let OnchainEvent::HTLCUpdate { input_idx: Some(input_idx), .. } = event.event { + if input_idx == htlc_input_idx { Some(event.confirmation_threshold()) } else { None } + } else { None } + }); + if let Some(conf_thresh) = htlc_update_pending { + res.push(Balance::ClaimableAwaitingConfirmations { + claimable_amount_satoshis: htlc.amount_msat / 1000, + confirmation_height: conf_thresh, + }); + } else { + res.push(Balance::MaybeClaimableHTLCAwaitingTimeout { + claimable_amount_satoshis: htlc.amount_msat / 1000, + claimable_height: htlc.cltv_expiry, + }); + } + } else if us.payment_preimages.get(&htlc.payment_hash).is_some() { + // Otherwise (the payment was inbound), only expose it as claimable if + // we know the preimage. + // Note that if there is a pending claim, but it did not use the + // preimage, we lost funds to our counterparty! We will then continue + // to show it as ContentiousClaimable until ANTI_REORG_DELAY. + let htlc_spend_pending = us.onchain_events_awaiting_threshold_conf.iter().find_map(|event| { + if let OnchainEvent::HTLCSpendConfirmation { input_idx, preimage, .. } = event.event { + if input_idx == htlc_input_idx { + Some((event.confirmation_threshold(), preimage.is_some())) + } else { None } + } else { None } + }); + if let Some((conf_thresh, true)) = htlc_spend_pending { + res.push(Balance::ClaimableAwaitingConfirmations { + claimable_amount_satoshis: htlc.amount_msat / 1000, + confirmation_height: conf_thresh, + }); + } else { + res.push(Balance::ContentiousClaimable { + claimable_amount_satoshis: htlc.amount_msat / 1000, + timeout_height: htlc.cltv_expiry, + }); + } + } + } + } + } + } + + if let Some(txid) = confirmed_txid { + let mut found_commitment_tx = false; + if Some(txid) == us.current_counterparty_commitment_txid || Some(txid) == us.prev_counterparty_commitment_txid { + walk_htlcs!(false, us.counterparty_claimable_outpoints.get(&txid).unwrap().iter().map(|(a, _)| a)); + if let Some(conf_thresh) = pending_commitment_tx_conf_thresh { + if let Some(value) = us.onchain_events_awaiting_threshold_conf.iter().find_map(|event| { + if let OnchainEvent::MaturingOutput { + descriptor: SpendableOutputDescriptor::StaticPaymentOutput(descriptor) + } = &event.event { + Some(descriptor.output.value) + } else { None } + }) { + res.push(Balance::ClaimableAwaitingConfirmations { + claimable_amount_satoshis: value, + confirmation_height: conf_thresh, + }); + } else { + // If a counterparty commitment transaction is awaiting confirmation, we + // should either have a StaticPaymentOutput MaturingOutput event awaiting + // confirmation with the same height or have never met our dust amount. + } + } + found_commitment_tx = true; + } else if txid == us.current_holder_commitment_tx.txid { + walk_htlcs!(true, us.current_holder_commitment_tx.htlc_outputs.iter().map(|(a, _, _)| a)); + if let Some(conf_thresh) = pending_commitment_tx_conf_thresh { + res.push(Balance::ClaimableAwaitingConfirmations { + claimable_amount_satoshis: us.current_holder_commitment_tx.to_self_value_sat, + confirmation_height: conf_thresh, + }); + } + found_commitment_tx = true; + } else if let Some(prev_commitment) = &us.prev_holder_signed_commitment_tx { + if txid == prev_commitment.txid { + walk_htlcs!(true, prev_commitment.htlc_outputs.iter().map(|(a, _, _)| a)); + if let Some(conf_thresh) = pending_commitment_tx_conf_thresh { + res.push(Balance::ClaimableAwaitingConfirmations { + claimable_amount_satoshis: prev_commitment.to_self_value_sat, + confirmation_height: conf_thresh, + }); + } + found_commitment_tx = true; + } + } + if !found_commitment_tx { + if let Some(conf_thresh) = pending_commitment_tx_conf_thresh { + // We blindly assume this is a cooperative close transaction here, and that + // neither us nor our counterparty misbehaved. At worst we've under-estimated + // the amount we can claim as we'll punish a misbehaving counterparty. + res.push(Balance::ClaimableAwaitingConfirmations { + claimable_amount_satoshis: us.current_holder_commitment_tx.to_self_value_sat, + confirmation_height: conf_thresh, + }); + } + } + // TODO: Add logic to provide claimable balances for counterparty broadcasting revoked + // outputs. + } else { + let mut claimable_inbound_htlc_value_sat = 0; + for (htlc, _, _) in us.current_holder_commitment_tx.htlc_outputs.iter() { + if htlc.transaction_output_index.is_none() { continue; } + if htlc.offered { + res.push(Balance::MaybeClaimableHTLCAwaitingTimeout { + claimable_amount_satoshis: htlc.amount_msat / 1000, + claimable_height: htlc.cltv_expiry, + }); + } else if us.payment_preimages.get(&htlc.payment_hash).is_some() { + claimable_inbound_htlc_value_sat += htlc.amount_msat / 1000; + } + } + res.push(Balance::ClaimableOnChannelClose { + claimable_amount_satoshis: us.current_holder_commitment_tx.to_self_value_sat + claimable_inbound_htlc_value_sat, + }); + } + + res + } + + /// Gets the set of outbound HTLCs which are pending resolution in this channel. + /// This is used to reconstruct pending outbound payments on restart in the ChannelManager. + pub(crate) fn get_pending_outbound_htlcs(&self) -> HashMap { + let mut res = HashMap::new(); + let us = self.inner.lock().unwrap(); + + macro_rules! walk_htlcs { + ($holder_commitment: expr, $htlc_iter: expr) => { + for (htlc, source) in $htlc_iter { + if us.htlcs_resolved_on_chain.iter().any(|v| Some(v.input_idx) == htlc.transaction_output_index) { + // We should assert that funding_spend_confirmed is_some() here, but we + // have some unit tests which violate HTLC transaction CSVs entirely and + // would fail. + // TODO: Once tests all connect transactions at consensus-valid times, we + // should assert here like we do in `get_claimable_balances`. + } else if htlc.offered == $holder_commitment { + // If the payment was outbound, check if there's an HTLCUpdate + // indicating we have spent this HTLC with a timeout, claiming it back + // and awaiting confirmations on it. + let htlc_update_confd = us.onchain_events_awaiting_threshold_conf.iter().any(|event| { + if let OnchainEvent::HTLCUpdate { input_idx: Some(input_idx), .. } = event.event { + // If the HTLC was timed out, we wait for ANTI_REORG_DELAY blocks + // before considering it "no longer pending" - this matches when we + // provide the ChannelManager an HTLC failure event. + Some(input_idx) == htlc.transaction_output_index && + us.best_block.height() >= event.height + ANTI_REORG_DELAY - 1 + } else if let OnchainEvent::HTLCSpendConfirmation { input_idx, .. } = event.event { + // If the HTLC was fulfilled with a preimage, we consider the HTLC + // immediately non-pending, matching when we provide ChannelManager + // the preimage. + Some(input_idx) == htlc.transaction_output_index + } else { false } + }); + if !htlc_update_confd { + res.insert(source.clone(), htlc.clone()); + } + } + } + } + } + + // We're only concerned with the confirmation count of HTLC transactions, and don't + // actually care how many confirmations a commitment transaction may or may not have. Thus, + // we look for either a FundingSpendConfirmation event or a funding_spend_confirmed. + let confirmed_txid = us.funding_spend_confirmed.or_else(|| { + us.onchain_events_awaiting_threshold_conf.iter().find_map(|event| { + if let OnchainEvent::FundingSpendConfirmation { .. } = event.event { + Some(event.txid) + } else { None } + }) + }); + if let Some(txid) = confirmed_txid { + if Some(txid) == us.current_counterparty_commitment_txid || Some(txid) == us.prev_counterparty_commitment_txid { + walk_htlcs!(false, us.counterparty_claimable_outpoints.get(&txid).unwrap().iter().filter_map(|(a, b)| { + if let &Some(ref source) = b { + Some((a, &**source)) + } else { None } + })); + } else if txid == us.current_holder_commitment_tx.txid { + walk_htlcs!(true, us.current_holder_commitment_tx.htlc_outputs.iter().filter_map(|(a, _, c)| { + if let Some(source) = c { Some((a, source)) } else { None } + })); + } else if let Some(prev_commitment) = &us.prev_holder_signed_commitment_tx { + if txid == prev_commitment.txid { + walk_htlcs!(true, prev_commitment.htlc_outputs.iter().filter_map(|(a, _, c)| { + if let Some(source) = c { Some((a, source)) } else { None } + })); + } + } + } else { + // If we have not seen a commitment transaction on-chain (ie the channel is not yet + // closed), just examine the available counterparty commitment transactions. See docs + // on `fail_unbroadcast_htlcs`, below, for justification. + macro_rules! walk_counterparty_commitment { + ($txid: expr) => { + if let Some(ref latest_outpoints) = us.counterparty_claimable_outpoints.get($txid) { + for &(ref htlc, ref source_option) in latest_outpoints.iter() { + if let &Some(ref source) = source_option { + res.insert((**source).clone(), htlc.clone()); + } + } + } + } + } + if let Some(ref txid) = us.current_counterparty_commitment_txid { + walk_counterparty_commitment!(txid); + } + if let Some(ref txid) = us.prev_counterparty_commitment_txid { + walk_counterparty_commitment!(txid); + } + } + + res + } } /// Compares a broadcasted commitment transaction's HTLCs with those in the latest state, @@ -1285,6 +1668,7 @@ macro_rules! fail_unbroadcast_htlcs { source: (**source).clone(), payment_hash: htlc.payment_hash.clone(), onchain_value_satoshis: Some(htlc.amount_msat / 1000), + input_idx: None, }, }; log_trace!($logger, "Failing HTLC with payment_hash {} from {} counterparty commitment tx due to broadcast of {} commitment transaction, waiting for confirmation (at height {})", @@ -1486,7 +1870,7 @@ impl ChannelMonitorImpl { log_info!(logger, "Broadcasting local {}", log_tx!(tx)); broadcaster.broadcast_transaction(tx); } - self.pending_monitor_events.push(MonitorEvent::CommitmentTxBroadcasted(self.funding_info.0)); + self.pending_monitor_events.push(MonitorEvent::CommitmentTxConfirmed(self.funding_info.0)); } pub fn update_monitor(&mut self, updates: &ChannelMonitorUpdate, broadcaster: &B, fee_estimator: &F, logger: &L) -> Result<(), MonitorUpdateError> @@ -1534,7 +1918,7 @@ impl ChannelMonitorImpl { } else if !self.holder_tx_signed { log_error!(logger, "You have a toxic holder commitment transaction avaible in channel monitor, read comment in ChannelMonitor::get_latest_holder_commitment_txn to be informed of manual action to take"); } else { - // If we generated a MonitorEvent::CommitmentTxBroadcasted, the ChannelManager + // If we generated a MonitorEvent::CommitmentTxConfirmed, the ChannelManager // will still give us a ChannelForceClosed event with !should_broadcast, but we // shouldn't print the scary warning above. log_info!(logger, "Channel off-chain state closed after we broadcasted our latest commitment transaction."); @@ -1804,7 +2188,8 @@ impl ChannelMonitorImpl { /// Attempts to claim any claimable HTLCs in a commitment transaction which was not (yet) /// revoked using data in holder_claimable_outpoints. /// Should not be used if check_spend_revoked_transaction succeeds. - fn check_spend_holder_transaction(&mut self, tx: &Transaction, height: u32, logger: &L) -> (Vec, TransactionOutputs) where L::Target: Logger { + /// Returns None unless the transaction is definitely one of our commitment transactions. + fn check_spend_holder_transaction(&mut self, tx: &Transaction, height: u32, logger: &L) -> Option<(Vec, TransactionOutputs)> where L::Target: Logger { let commitment_txid = tx.txid(); let mut claim_requests = Vec::new(); let mut watch_outputs = Vec::new(); @@ -1839,9 +2224,10 @@ impl ChannelMonitorImpl { } if is_holder_tx { + Some((claim_requests, (commitment_txid, watch_outputs))) + } else { + None } - - (claim_requests, (commitment_txid, watch_outputs)) } pub fn get_latest_holder_commitment_txn(&mut self, logger: &L) -> Vec where L::Target: Logger { @@ -1973,20 +2359,32 @@ impl ChannelMonitorImpl { // filters. let prevout = &tx.input[0].previous_output; if prevout.txid == self.funding_info.0.txid && prevout.vout == self.funding_info.0.index as u32 { + let mut balance_spendable_csv = None; + log_info!(logger, "Channel closed by funding output spend in txid {}.", log_bytes!(tx.txid())); if (tx.input[0].sequence >> 8*3) as u8 == 0x80 && (tx.lock_time >> 8*3) as u8 == 0x20 { let (mut new_outpoints, new_outputs) = self.check_spend_counterparty_transaction(&tx, height, &logger); if !new_outputs.1.is_empty() { watch_outputs.push(new_outputs); } + claimable_outpoints.append(&mut new_outpoints); if new_outpoints.is_empty() { - let (mut new_outpoints, new_outputs) = self.check_spend_holder_transaction(&tx, height, &logger); - if !new_outputs.1.is_empty() { - watch_outputs.push(new_outputs); + if let Some((mut new_outpoints, new_outputs)) = self.check_spend_holder_transaction(&tx, height, &logger) { + if !new_outputs.1.is_empty() { + watch_outputs.push(new_outputs); + } + claimable_outpoints.append(&mut new_outpoints); + balance_spendable_csv = Some(self.on_holder_tx_csv); } - claimable_outpoints.append(&mut new_outpoints); } - claimable_outpoints.append(&mut new_outpoints); } + let txid = tx.txid(); + self.onchain_events_awaiting_threshold_conf.push(OnchainEventEntry { + txid, + height: height, + event: OnchainEvent::FundingSpendConfirmation { + on_local_output_csv: balance_spendable_csv, + }, + }); } else { if let Some(&commitment_number) = self.counterparty_commitment_txn_on_chain.get(&prevout.txid) { let (mut new_outpoints, new_outputs_option) = self.check_spend_counterparty_htlc(&tx, commitment_number, height, &logger); @@ -2042,7 +2440,7 @@ impl ChannelMonitorImpl { let funding_outp = HolderFundingOutput::build(self.funding_redeemscript.clone()); let commitment_package = PackageTemplate::build_package(self.funding_info.0.txid.clone(), self.funding_info.0.index as u32, PackageSolvingData::HolderFundingOutput(funding_outp), self.best_block.height(), false, self.best_block.height()); claimable_outpoints.push(commitment_package); - self.pending_monitor_events.push(MonitorEvent::CommitmentTxBroadcasted(self.funding_info.0)); + self.pending_monitor_events.push(MonitorEvent::CommitmentTxConfirmed(self.funding_info.0)); let commitment_tx = self.onchain_tx_handler.get_fully_signed_holder_tx(&self.funding_redeemscript); self.holder_tx_signed = true; // Because we're broadcasting a commitment transaction, we should construct the package @@ -2074,7 +2472,7 @@ impl ChannelMonitorImpl { .iter() .filter_map(|entry| match &entry.event { OnchainEvent::HTLCUpdate { source, .. } => Some(source), - OnchainEvent::MaturingOutput { .. } => None, + _ => None, }) .collect(); #[cfg(debug_assertions)] @@ -2083,7 +2481,7 @@ impl ChannelMonitorImpl { // Produce actionable events from on-chain events having reached their threshold. for entry in onchain_events_reaching_threshold_conf.drain(..) { match entry.event { - OnchainEvent::HTLCUpdate { ref source, payment_hash, onchain_value_satoshis } => { + OnchainEvent::HTLCUpdate { ref source, payment_hash, onchain_value_satoshis, input_idx } => { // Check for duplicate HTLC resolutions. #[cfg(debug_assertions)] { @@ -2107,13 +2505,22 @@ impl ChannelMonitorImpl { source: source.clone(), onchain_value_satoshis, })); + if let Some(idx) = input_idx { + self.htlcs_resolved_on_chain.push(IrrevocablyResolvedHTLC { input_idx: idx, payment_preimage: None }); + } }, OnchainEvent::MaturingOutput { descriptor } => { log_debug!(logger, "Descriptor {} has got enough confirmations to be passed upstream", log_spendable!(descriptor)); self.pending_events.push(Event::SpendableOutputs { outputs: vec![descriptor] }); - } + }, + OnchainEvent::HTLCSpendConfirmation { input_idx, preimage, .. } => { + self.htlcs_resolved_on_chain.push(IrrevocablyResolvedHTLC { input_idx, payment_preimage: preimage }); + }, + OnchainEvent::FundingSpendConfirmation { .. } => { + self.funding_spend_confirmed = Some(entry.txid); + }, } } @@ -2291,15 +2698,34 @@ impl ChannelMonitorImpl { let revocation_sig_claim = (input.witness.len() == 3 && HTLCType::scriptlen_to_htlctype(input.witness[2].len()) == Some(HTLCType::OfferedHTLC) && input.witness[1].len() == 33) || (input.witness.len() == 3 && HTLCType::scriptlen_to_htlctype(input.witness[2].len()) == Some(HTLCType::AcceptedHTLC) && input.witness[1].len() == 33); let accepted_preimage_claim = input.witness.len() == 5 && HTLCType::scriptlen_to_htlctype(input.witness[4].len()) == Some(HTLCType::AcceptedHTLC); - let offered_preimage_claim = input.witness.len() == 3 && HTLCType::scriptlen_to_htlctype(input.witness[2].len()) == Some(HTLCType::OfferedHTLC); + #[cfg(not(fuzzing))] + let accepted_timeout_claim = input.witness.len() == 3 && HTLCType::scriptlen_to_htlctype(input.witness[2].len()) == Some(HTLCType::AcceptedHTLC) && !revocation_sig_claim; + let offered_preimage_claim = input.witness.len() == 3 && HTLCType::scriptlen_to_htlctype(input.witness[2].len()) == Some(HTLCType::OfferedHTLC) && !revocation_sig_claim; + #[cfg(not(fuzzing))] + let offered_timeout_claim = input.witness.len() == 5 && HTLCType::scriptlen_to_htlctype(input.witness[4].len()) == Some(HTLCType::OfferedHTLC); + + let mut payment_preimage = PaymentPreimage([0; 32]); + if accepted_preimage_claim { + payment_preimage.0.copy_from_slice(&input.witness[3]); + } else if offered_preimage_claim { + payment_preimage.0.copy_from_slice(&input.witness[1]); + } macro_rules! log_claim { ($tx_info: expr, $holder_tx: expr, $htlc: expr, $source_avail: expr) => { - // We found the output in question, but aren't failing it backwards - // as we have no corresponding source and no valid counterparty commitment txid - // to try a weak source binding with same-hash, same-value still-valid offered HTLC. - // This implies either it is an inbound HTLC or an outbound HTLC on a revoked transaction. let outbound_htlc = $holder_tx == $htlc.offered; + // HTLCs must either be claimed by a matching script type or through the + // revocation path: + #[cfg(not(fuzzing))] // Note that the fuzzer is not bound by pesky things like "signatures" + debug_assert!(!$htlc.offered || offered_preimage_claim || offered_timeout_claim || revocation_sig_claim); + #[cfg(not(fuzzing))] // Note that the fuzzer is not bound by pesky things like "signatures" + debug_assert!($htlc.offered || accepted_preimage_claim || accepted_timeout_claim || revocation_sig_claim); + // Further, only exactly one of the possible spend paths should have been + // matched by any HTLC spend: + #[cfg(not(fuzzing))] // Note that the fuzzer is not bound by pesky things like "signatures" + debug_assert_eq!(accepted_preimage_claim as u8 + accepted_timeout_claim as u8 + + offered_preimage_claim as u8 + offered_timeout_claim as u8 + + revocation_sig_claim as u8, 1); if ($holder_tx && revocation_sig_claim) || (outbound_htlc && !$source_avail && (accepted_preimage_claim || offered_preimage_claim)) { log_error!(logger, "Input spending {} ({}:{}) in {} resolves {} HTLC with payment hash {} with {}!", @@ -2344,13 +2770,37 @@ impl ChannelMonitorImpl { // resolve the source HTLC with the original sender. payment_data = Some(((*source).clone(), htlc_output.payment_hash, htlc_output.amount_msat)); } else if !$holder_tx { - check_htlc_valid_counterparty!(self.current_counterparty_commitment_txid, htlc_output); + check_htlc_valid_counterparty!(self.current_counterparty_commitment_txid, htlc_output); if payment_data.is_none() { check_htlc_valid_counterparty!(self.prev_counterparty_commitment_txid, htlc_output); } } if payment_data.is_none() { log_claim!($tx_info, $holder_tx, htlc_output, false); + let outbound_htlc = $holder_tx == htlc_output.offered; + if !outbound_htlc || revocation_sig_claim { + self.onchain_events_awaiting_threshold_conf.push(OnchainEventEntry { + txid: tx.txid(), height, + event: OnchainEvent::HTLCSpendConfirmation { + input_idx: input.previous_output.vout, + preimage: if accepted_preimage_claim || offered_preimage_claim { + Some(payment_preimage) } else { None }, + // If this is a payment to us (!outbound_htlc, above), + // wait for the CSV delay before dropping the HTLC from + // claimable balance if the claim was an HTLC-Success + // transaction. + on_to_local_output_csv: if accepted_preimage_claim { + Some(self.on_holder_tx_csv) } else { None }, + }, + }); + } else { + // Outbound claims should always have payment_data, unless + // we've already failed the HTLC as the commitment transaction + // which was broadcasted was revoked. In that case, we should + // spend the HTLC output here immediately, and expose that fact + // as a Balance, something which we do not yet do. + // TODO: Track the above as claimable! + } continue 'outer_loop; } } @@ -2376,11 +2826,18 @@ impl ChannelMonitorImpl { // Check that scan_commitment, above, decided there is some source worth relaying an // HTLC resolution backwards to and figure out whether we learned a preimage from it. if let Some((source, payment_hash, amount_msat)) = payment_data { - let mut payment_preimage = PaymentPreimage([0; 32]); if accepted_preimage_claim { if !self.pending_monitor_events.iter().any( |update| if let &MonitorEvent::HTLCEvent(ref upd) = update { upd.source == source } else { false }) { - payment_preimage.0.copy_from_slice(&input.witness[3]); + self.onchain_events_awaiting_threshold_conf.push(OnchainEventEntry { + txid: tx.txid(), + height, + event: OnchainEvent::HTLCSpendConfirmation { + input_idx: input.previous_output.vout, + preimage: Some(payment_preimage), + on_to_local_output_csv: None, + }, + }); self.pending_monitor_events.push(MonitorEvent::HTLCEvent(HTLCUpdate { source, payment_preimage: Some(payment_preimage), @@ -2393,7 +2850,15 @@ impl ChannelMonitorImpl { |update| if let &MonitorEvent::HTLCEvent(ref upd) = update { upd.source == source } else { false }) { - payment_preimage.0.copy_from_slice(&input.witness[1]); + self.onchain_events_awaiting_threshold_conf.push(OnchainEventEntry { + txid: tx.txid(), + height, + event: OnchainEvent::HTLCSpendConfirmation { + input_idx: input.previous_output.vout, + preimage: Some(payment_preimage), + on_to_local_output_csv: None, + }, + }); self.pending_monitor_events.push(MonitorEvent::HTLCEvent(HTLCUpdate { source, payment_preimage: Some(payment_preimage), @@ -2417,6 +2882,7 @@ impl ChannelMonitorImpl { event: OnchainEvent::HTLCUpdate { source, payment_hash, onchain_value_satoshis: Some(amount_msat / 1000), + input_idx: Some(input.previous_output.vout), }, }; log_info!(logger, "Failing HTLC with payment_hash {} timeout by a spend tx, waiting for confirmation (at height {})", log_bytes!(payment_hash.0), entry.confirmation_threshold()); @@ -2494,53 +2960,6 @@ impl ChannelMonitorImpl { } } -/// `Persist` defines behavior for persisting channel monitors: this could mean -/// writing once to disk, and/or uploading to one or more backup services. -/// -/// Note that for every new monitor, you **must** persist the new `ChannelMonitor` -/// to disk/backups. And, on every update, you **must** persist either the -/// `ChannelMonitorUpdate` or the updated monitor itself. Otherwise, there is risk -/// of situations such as revoking a transaction, then crashing before this -/// revocation can be persisted, then unintentionally broadcasting a revoked -/// transaction and losing money. This is a risk because previous channel states -/// are toxic, so it's important that whatever channel state is persisted is -/// kept up-to-date. -pub trait Persist { - /// Persist a new channel's data. The data can be stored any way you want, but - /// the identifier provided by Rust-Lightning is the channel's outpoint (and - /// it is up to you to maintain a correct mapping between the outpoint and the - /// stored channel data). Note that you **must** persist every new monitor to - /// disk. See the `Persist` trait documentation for more details. - /// - /// See [`ChannelMonitor::write`] for writing out a `ChannelMonitor`, - /// and [`ChannelMonitorUpdateErr`] for requirements when returning errors. - fn persist_new_channel(&self, id: OutPoint, data: &ChannelMonitor) -> Result<(), ChannelMonitorUpdateErr>; - - /// Update one channel's data. The provided `ChannelMonitor` has already - /// applied the given update. - /// - /// Note that on every update, you **must** persist either the - /// `ChannelMonitorUpdate` or the updated monitor itself to disk/backups. See - /// the `Persist` trait documentation for more details. - /// - /// If an implementer chooses to persist the updates only, they need to make - /// sure that all the updates are applied to the `ChannelMonitors` *before* - /// the set of channel monitors is given to the `ChannelManager` - /// deserialization routine. See [`ChannelMonitor::update_monitor`] for - /// applying a monitor update to a monitor. If full `ChannelMonitors` are - /// persisted, then there is no need to persist individual updates. - /// - /// Note that there could be a performance tradeoff between persisting complete - /// channel monitors on every update vs. persisting only updates and applying - /// them in batches. The size of each monitor grows `O(number of state updates)` - /// whereas updates are small and `O(1)`. - /// - /// See [`ChannelMonitor::write`] for writing out a `ChannelMonitor`, - /// [`ChannelMonitorUpdate::write`] for writing out an update, and - /// [`ChannelMonitorUpdateErr`] for requirements when returning errors. - fn update_persisted_channel(&self, id: OutPoint, update: &ChannelMonitorUpdate, data: &ChannelMonitor) -> Result<(), ChannelMonitorUpdateErr>; -} - impl chain::Listen for (ChannelMonitor, T, F, L) where T::Target: BroadcasterInterface, @@ -2725,14 +3144,15 @@ impl<'a, Signer: Sign, K: KeysInterface> ReadableArgs<&'a K> } let pending_monitor_events_len: u64 = Readable::read(reader)?; - let mut pending_monitor_events = Vec::with_capacity(cmp::min(pending_monitor_events_len as usize, MAX_ALLOC_SIZE / (32 + 8*3))); + let mut pending_monitor_events = Some( + Vec::with_capacity(cmp::min(pending_monitor_events_len as usize, MAX_ALLOC_SIZE / (32 + 8*3)))); for _ in 0..pending_monitor_events_len { let ev = match ::read(reader)? { 0 => MonitorEvent::HTLCEvent(Readable::read(reader)?), - 1 => MonitorEvent::CommitmentTxBroadcasted(funding_info.0), + 1 => MonitorEvent::CommitmentTxConfirmed(funding_info.0), _ => return Err(DecodeError::InvalidValue) }; - pending_monitor_events.push(ev); + pending_monitor_events.as_mut().unwrap().push(ev); } let pending_events_len: u64 = Readable::read(reader)?; @@ -2788,7 +3208,13 @@ impl<'a, Signer: Sign, K: KeysInterface> ReadableArgs<&'a K> return Err(DecodeError::InvalidValue); } - read_tlv_fields!(reader, {}); + let mut funding_spend_confirmed = None; + let mut htlcs_resolved_on_chain = Some(Vec::new()); + read_tlv_fields!(reader, { + (1, funding_spend_confirmed, option), + (3, htlcs_resolved_on_chain, vec_type), + (5, pending_monitor_events, vec_type), + }); let mut secp_ctx = Secp256k1::new(); secp_ctx.seeded_randomize(&keys_manager.get_secure_random_bytes()); @@ -2827,7 +3253,7 @@ impl<'a, Signer: Sign, K: KeysInterface> ReadableArgs<&'a K> current_holder_commitment_number, payment_preimages, - pending_monitor_events, + pending_monitor_events: pending_monitor_events.unwrap(), pending_events, onchain_events_awaiting_threshold_conf, @@ -2837,6 +3263,8 @@ impl<'a, Signer: Sign, K: KeysInterface> ReadableArgs<&'a K> lockdown_from_offchain, holder_tx_signed, + funding_spend_confirmed, + htlcs_resolved_on_chain: htlcs_resolved_on_chain.unwrap(), best_block,