Add transaction index in watched_outputs
[rust-lightning] / lightning / src / chain / channelmonitor.rs
index 5b11835707cec086f92711218bc8c158350161f5..e0f9d607817dfc602f9b4547e7fc8387b5b503c8 100644 (file)
@@ -42,18 +42,15 @@ use ln::chan_utils;
 use ln::chan_utils::{CounterpartyCommitmentSecrets, HTLCOutputInCommitment, HolderCommitmentTransaction, HTLCType};
 use ln::channelmanager::{HTLCSource, PaymentPreimage, PaymentHash};
 use ln::onchaintx::{OnchainTxHandler, InputDescriptors};
-use chain;
-use chain::Filter;
 use chain::chaininterface::{BroadcasterInterface, FeeEstimator};
 use chain::transaction::{OutPoint, TransactionData};
 use chain::keysinterface::{SpendableOutputDescriptor, ChannelKeys};
 use util::logger::Logger;
 use util::ser::{Readable, MaybeReadable, Writer, Writeable, U48};
-use util::{byte_utils, events};
+use util::byte_utils;
 use util::events::Event;
 
 use std::collections::{HashMap, HashSet, hash_map};
-use std::sync::Mutex;
 use std::{cmp, mem};
 use std::ops::Deref;
 use std::io::Error;
@@ -189,185 +186,6 @@ pub struct HTLCUpdate {
 }
 impl_writeable!(HTLCUpdate, 0, { payment_hash, payment_preimage, source });
 
-/// An implementation of [`chain::Watch`] for monitoring channels.
-///
-/// Connected and disconnected blocks must be provided to `ChainMonitor` as documented by
-/// [`chain::Watch`]. May be used in conjunction with [`ChannelManager`] to monitor channels locally
-/// or used independently to monitor channels remotely.
-///
-/// [`chain::Watch`]: ../trait.Watch.html
-/// [`ChannelManager`]: ../../ln/channelmanager/struct.ChannelManager.html
-pub struct ChainMonitor<ChanSigner: ChannelKeys, C: Deref, T: Deref, F: Deref, L: Deref>
-       where C::Target: chain::Filter,
-        T::Target: BroadcasterInterface,
-        F::Target: FeeEstimator,
-        L::Target: Logger,
-{
-       /// The monitors
-       pub monitors: Mutex<HashMap<OutPoint, ChannelMonitor<ChanSigner>>>,
-       chain_source: Option<C>,
-       broadcaster: T,
-       logger: L,
-       fee_estimator: F
-}
-
-impl<ChanSigner: ChannelKeys, C: Deref, T: Deref, F: Deref, L: Deref> ChainMonitor<ChanSigner, C, T, F, L>
-       where C::Target: chain::Filter,
-             T::Target: BroadcasterInterface,
-             F::Target: FeeEstimator,
-             L::Target: Logger,
-{
-       /// Dispatches to per-channel monitors, which are responsible for updating their on-chain view
-       /// of a channel and reacting accordingly based on transactions in the connected block. See
-       /// [`ChannelMonitor::block_connected`] for details. Any HTLCs that were resolved on chain will
-       /// be returned by [`chain::Watch::release_pending_monitor_events`].
-       ///
-       /// Calls back to [`chain::Filter`] if any monitor indicated new outputs to watch, returning
-       /// `true` if so. Subsequent calls must not exclude any transactions matching the new outputs
-       /// nor any in-block descendants of such transactions. It is not necessary to re-fetch the block
-       /// to obtain updated `txdata`.
-       ///
-       /// [`ChannelMonitor::block_connected`]: struct.ChannelMonitor.html#method.block_connected
-       /// [`chain::Watch::release_pending_monitor_events`]: ../trait.Watch.html#tymethod.release_pending_monitor_events
-       /// [`chain::Filter`]: ../trait.Filter.html
-       pub fn block_connected(&self, header: &BlockHeader, txdata: &TransactionData, height: u32) -> bool {
-               let mut has_new_outputs_to_watch = false;
-               {
-                       let mut monitors = self.monitors.lock().unwrap();
-                       for monitor in monitors.values_mut() {
-                               let mut txn_outputs = monitor.block_connected(header, txdata, height, &*self.broadcaster, &*self.fee_estimator, &*self.logger);
-                               has_new_outputs_to_watch |= !txn_outputs.is_empty();
-
-                               if let Some(ref chain_source) = self.chain_source {
-                                       for (txid, outputs) in txn_outputs.drain(..) {
-                                               for (idx, output) in outputs.iter().enumerate() {
-                                                       chain_source.register_output(&OutPoint { txid, index: idx as u16 }, &output.script_pubkey);
-                                               }
-                                       }
-                               }
-                       }
-               }
-               has_new_outputs_to_watch
-       }
-
-       /// Dispatches to per-channel monitors, which are responsible for updating their on-chain view
-       /// of a channel based on the disconnected block. See [`ChannelMonitor::block_disconnected`] for
-       /// details.
-       ///
-       /// [`ChannelMonitor::block_disconnected`]: struct.ChannelMonitor.html#method.block_disconnected
-       pub fn block_disconnected(&self, header: &BlockHeader, disconnected_height: u32) {
-               let mut monitors = self.monitors.lock().unwrap();
-               for monitor in monitors.values_mut() {
-                       monitor.block_disconnected(header, disconnected_height, &*self.broadcaster, &*self.fee_estimator, &*self.logger);
-               }
-       }
-
-       /// Creates a new `ChainMonitor` used to watch on-chain activity pertaining to channels.
-       ///
-       /// When an optional chain source implementing [`chain::Filter`] is provided, the chain monitor
-       /// will call back to it indicating transactions and outputs of interest. This allows clients to
-       /// pre-filter blocks or only fetch blocks matching a compact filter. Otherwise, clients may
-       /// always need to fetch full blocks absent another means for determining which blocks contain
-       /// transactions relevant to the watched channels.
-       ///
-       /// [`chain::Filter`]: ../trait.Filter.html
-       pub fn new(chain_source: Option<C>, broadcaster: T, logger: L, feeest: F) -> Self {
-               Self {
-                       monitors: Mutex::new(HashMap::new()),
-                       chain_source,
-                       broadcaster,
-                       logger,
-                       fee_estimator: feeest,
-               }
-       }
-
-       /// Adds the monitor that watches the channel referred to by the given outpoint.
-       ///
-       /// Calls back to [`chain::Filter`] with the funding transaction and outputs to watch.
-       ///
-       /// [`chain::Filter`]: ../trait.Filter.html
-       fn add_monitor(&self, outpoint: OutPoint, monitor: ChannelMonitor<ChanSigner>) -> Result<(), MonitorUpdateError> {
-               let mut monitors = self.monitors.lock().unwrap();
-               let entry = match monitors.entry(outpoint) {
-                       hash_map::Entry::Occupied(_) => return Err(MonitorUpdateError("Channel monitor for given outpoint is already present")),
-                       hash_map::Entry::Vacant(e) => e,
-               };
-               {
-                       let funding_txo = monitor.get_funding_txo();
-                       log_trace!(self.logger, "Got new Channel Monitor for channel {}", log_bytes!(funding_txo.0.to_channel_id()[..]));
-
-                       if let Some(ref chain_source) = self.chain_source {
-                               chain_source.register_tx(&funding_txo.0.txid, &funding_txo.1);
-                               for (txid, outputs) in monitor.get_outputs_to_watch().iter() {
-                                       for (idx, script_pubkey) in outputs.iter().enumerate() {
-                                               chain_source.register_output(&OutPoint { txid: *txid, index: idx as u16 }, &script_pubkey);
-                                       }
-                               }
-                       }
-               }
-               entry.insert(monitor);
-               Ok(())
-       }
-
-       /// Updates the monitor that watches the channel referred to by the given outpoint.
-       fn update_monitor(&self, outpoint: OutPoint, update: ChannelMonitorUpdate) -> Result<(), MonitorUpdateError> {
-               let mut monitors = self.monitors.lock().unwrap();
-               match monitors.get_mut(&outpoint) {
-                       Some(orig_monitor) => {
-                               log_trace!(self.logger, "Updating Channel Monitor for channel {}", log_funding_info!(orig_monitor));
-                               orig_monitor.update_monitor(update, &self.broadcaster, &self.logger)
-                       },
-                       None => Err(MonitorUpdateError("No such monitor registered"))
-               }
-       }
-}
-
-impl<ChanSigner: ChannelKeys, C: Deref + Sync + Send, T: Deref + Sync + Send, F: Deref + Sync + Send, L: Deref + Sync + Send> chain::Watch for ChainMonitor<ChanSigner, C, T, F, L>
-       where C::Target: chain::Filter,
-             T::Target: BroadcasterInterface,
-             F::Target: FeeEstimator,
-             L::Target: Logger,
-{
-       type Keys = ChanSigner;
-
-       fn watch_channel(&self, funding_txo: OutPoint, monitor: ChannelMonitor<ChanSigner>) -> Result<(), ChannelMonitorUpdateErr> {
-               match self.add_monitor(funding_txo, monitor) {
-                       Ok(_) => Ok(()),
-                       Err(_) => Err(ChannelMonitorUpdateErr::PermanentFailure),
-               }
-       }
-
-       fn update_channel(&self, funding_txo: OutPoint, update: ChannelMonitorUpdate) -> Result<(), ChannelMonitorUpdateErr> {
-               match self.update_monitor(funding_txo, update) {
-                       Ok(_) => Ok(()),
-                       Err(_) => Err(ChannelMonitorUpdateErr::PermanentFailure),
-               }
-       }
-
-       fn release_pending_monitor_events(&self) -> Vec<MonitorEvent> {
-               let mut pending_monitor_events = Vec::new();
-               for chan in self.monitors.lock().unwrap().values_mut() {
-                       pending_monitor_events.append(&mut chan.get_and_clear_pending_monitor_events());
-               }
-               pending_monitor_events
-       }
-}
-
-impl<ChanSigner: ChannelKeys, C: Deref, T: Deref, F: Deref, L: Deref> events::EventsProvider for ChainMonitor<ChanSigner, C, T, F, L>
-       where C::Target: chain::Filter,
-             T::Target: BroadcasterInterface,
-             F::Target: FeeEstimator,
-             L::Target: Logger,
-{
-       fn get_and_clear_pending_events(&self) -> Vec<Event> {
-               let mut pending_events = Vec::new();
-               for chan in self.monitors.lock().unwrap().values_mut() {
-                       pending_events.append(&mut chan.get_and_clear_pending_events());
-               }
-               pending_events
-       }
-}
-
 /// If an HTLC expires within this many blocks, don't try to claim it in a shared transaction,
 /// instead claiming it in its own individual transaction.
 pub(crate) const CLTV_SHARED_CLAIM_BUFFER: u32 = 12;
@@ -813,7 +631,7 @@ pub struct ChannelMonitor<ChanSigner: ChannelKeys> {
        /// spending. Thus, in order to claim them via revocation key, we track all the counterparty
        /// commitment transactions which we find on-chain, mapping them to the commitment number which
        /// can be used to derive the revocation key and claim the transactions.
-       counterparty_commitment_txn_on_chain: HashMap<Txid, (u64, Vec<Script>)>,
+       counterparty_commitment_txn_on_chain: HashMap<Txid, u64>,
        /// Cache used to make pruning of payment_preimages faster.
        /// Maps payment_hash values to commitment numbers for counterparty transactions for non-revoked
        /// counterparty transactions (ie should remain pretty small).
@@ -848,7 +666,7 @@ pub struct ChannelMonitor<ChanSigner: ChannelKeys> {
        // interface knows about the TXOs that we want to be notified of spends of. We could probably
        // be smart and derive them from the above storage fields, but its much simpler and more
        // Obviously Correct (tm) if we just keep track of them explicitly.
-       outputs_to_watch: HashMap<Txid, Vec<Script>>,
+       outputs_to_watch: HashMap<Txid, Vec<(u32, Script)>>,
 
        #[cfg(test)]
        pub onchain_tx_handler: OnchainTxHandler<ChanSigner>,
@@ -1006,13 +824,9 @@ impl<ChanSigner: ChannelKeys + Writeable> ChannelMonitor<ChanSigner> {
                }
 
                writer.write_all(&byte_utils::be64_to_array(self.counterparty_commitment_txn_on_chain.len() as u64))?;
-               for (ref txid, &(commitment_number, ref txouts)) in self.counterparty_commitment_txn_on_chain.iter() {
+               for (ref txid, commitment_number) in self.counterparty_commitment_txn_on_chain.iter() {
                        writer.write_all(&txid[..])?;
-                       writer.write_all(&byte_utils::be48_to_array(commitment_number))?;
-                       (txouts.len() as u64).write(writer)?;
-                       for script in txouts.iter() {
-                               script.write(writer)?;
-                       }
+                       writer.write_all(&byte_utils::be48_to_array(*commitment_number))?;
                }
 
                writer.write_all(&byte_utils::be64_to_array(self.counterparty_hash_commitment_number.len() as u64))?;
@@ -1100,10 +914,11 @@ impl<ChanSigner: ChannelKeys + Writeable> ChannelMonitor<ChanSigner> {
                }
 
                (self.outputs_to_watch.len() as u64).write(writer)?;
-               for (txid, output_scripts) in self.outputs_to_watch.iter() {
+               for (txid, idx_scripts) in self.outputs_to_watch.iter() {
                        txid.write(writer)?;
-                       (output_scripts.len() as u64).write(writer)?;
-                       for script in output_scripts.iter() {
+                       (idx_scripts.len() as u64).write(writer)?;
+                       for (idx, script) in idx_scripts.iter() {
+                               idx.write(writer)?;
                                script.write(writer)?;
                        }
                }
@@ -1149,7 +964,7 @@ impl<ChanSigner: ChannelKeys> ChannelMonitor<ChanSigner> {
                onchain_tx_handler.provide_latest_holder_tx(initial_holder_commitment_tx);
 
                let mut outputs_to_watch = HashMap::new();
-               outputs_to_watch.insert(funding_info.0.txid, vec![funding_info.1.clone()]);
+               outputs_to_watch.insert(funding_info.0.txid, vec![(funding_info.0.index as u32, funding_info.1.clone())]);
 
                ChannelMonitor {
                        latest_update_id: 0,
@@ -1167,7 +982,7 @@ impl<ChanSigner: ChannelKeys> ChannelMonitor<ChanSigner> {
 
                        counterparty_tx_cache,
                        funding_redeemscript,
-                       channel_value_satoshis: channel_value_satoshis,
+                       channel_value_satoshis,
                        their_cur_revocation_points: None,
 
                        on_holder_tx_csv,
@@ -1315,7 +1130,7 @@ impl<ChanSigner: ChannelKeys> ChannelMonitor<ChanSigner> {
                        delayed_payment_key: commitment_tx.keys.broadcaster_delayed_payment_key,
                        per_commitment_point: commitment_tx.keys.per_commitment_point,
                        feerate_per_kw: commitment_tx.feerate_per_kw,
-                       htlc_outputs: htlc_outputs,
+                       htlc_outputs,
                };
                self.onchain_tx_handler.provide_latest_holder_tx(commitment_tx);
                self.current_holder_commitment_number = 0xffff_ffff_ffff - ((((sequence & 0xffffff) << 3*8) | (locktime as u64 & 0xffffff)) ^ self.commitment_transaction_number_obscure_factor);
@@ -1395,24 +1210,14 @@ impl<ChanSigner: ChannelKeys> ChannelMonitor<ChanSigner> {
        /// transaction), which we must learn about spends of via block_connected().
        ///
        /// (C-not exported) because we have no HashMap bindings
-       pub fn get_outputs_to_watch(&self) -> &HashMap<Txid, Vec<Script>> {
-               &self.outputs_to_watch
-       }
-
-       /// Gets the sets of all outpoints which this ChannelMonitor expects to hear about spends of.
-       /// Generally useful when deserializing as during normal operation the return values of
-       /// block_connected are sufficient to ensure all relevant outpoints are being monitored (note
-       /// that the get_funding_txo outpoint and transaction must also be monitored for!).
-       ///
-       /// (C-not exported) as there is no practical way to track lifetimes of returned values.
-       pub fn get_monitored_outpoints(&self) -> Vec<(Txid, u32, &Script)> {
-               let mut res = Vec::with_capacity(self.counterparty_commitment_txn_on_chain.len() * 2);
-               for (ref txid, &(_, ref outputs)) in self.counterparty_commitment_txn_on_chain.iter() {
-                       for (idx, output) in outputs.iter().enumerate() {
-                               res.push(((*txid).clone(), idx as u32, output));
-                       }
+       pub fn get_outputs_to_watch(&self) -> &HashMap<Txid, Vec<(u32, Script)>> {
+               // If we've detected a counterparty commitment tx on chain, we must include it in the set
+               // of outputs to watch for spends of, otherwise we're likely to lose user funds. Because
+               // its trivial to do, double-check that here.
+               for (txid, _) in self.counterparty_commitment_txn_on_chain.iter() {
+                       self.outputs_to_watch.get(txid).expect("Counterparty commitment txn which have been broadcast should have outputs registered");
                }
-               res
+               &self.outputs_to_watch
        }
 
        /// Get the list of HTLCs who's status has been updated on chain. This should be called by
@@ -1460,7 +1265,7 @@ impl<ChanSigner: ChannelKeys> ChannelMonitor<ChanSigner> {
        /// HTLC-Success/HTLC-Timeout transactions.
        /// Return updates for HTLC pending in the channel and failed automatically by the broadcast of
        /// revoked counterparty commitment tx
-       fn check_spend_counterparty_transaction<L: Deref>(&mut self, tx: &Transaction, height: u32, logger: &L) -> (Vec<ClaimRequest>, (Txid, Vec<TxOut>)) where L::Target: Logger {
+       fn check_spend_counterparty_transaction<L: Deref>(&mut self, tx: &Transaction, height: u32, logger: &L) -> (Vec<ClaimRequest>, (Txid, Vec<(u32, TxOut)>)) where L::Target: Logger {
                // Most secp and related errors trying to create keys means we have no hope of constructing
                // a spend transaction...so we return no transactions to broadcast
                let mut claimable_outpoints = Vec::new();
@@ -1515,8 +1320,10 @@ impl<ChanSigner: ChannelKeys> ChannelMonitor<ChanSigner> {
                        if !claimable_outpoints.is_empty() || per_commitment_option.is_some() { // ie we're confident this is actually ours
                                // We're definitely a counterparty commitment transaction!
                                log_trace!(logger, "Got broadcast of revoked counterparty commitment transaction, going to generate general spend tx with {} inputs", claimable_outpoints.len());
-                               watch_outputs.append(&mut tx.output.clone());
-                               self.counterparty_commitment_txn_on_chain.insert(commitment_txid, (commitment_number, tx.output.iter().map(|output| { output.script_pubkey.clone() }).collect()));
+                               for (idx, outp) in tx.output.iter().enumerate() {
+                                       watch_outputs.push((idx as u32, outp.clone()));
+                               }
+                               self.counterparty_commitment_txn_on_chain.insert(commitment_txid, commitment_number);
 
                                macro_rules! check_htlc_fails {
                                        ($txid: expr, $commitment_tx: expr) => {
@@ -1562,8 +1369,10 @@ impl<ChanSigner: ChannelKeys> ChannelMonitor<ChanSigner> {
                        // already processed the block, resulting in the counterparty_commitment_txn_on_chain entry
                        // not being generated by the above conditional. Thus, to be safe, we go ahead and
                        // insert it here.
-                       watch_outputs.append(&mut tx.output.clone());
-                       self.counterparty_commitment_txn_on_chain.insert(commitment_txid, (commitment_number, tx.output.iter().map(|output| { output.script_pubkey.clone() }).collect()));
+                       for (idx, outp) in tx.output.iter().enumerate() {
+                               watch_outputs.push((idx as u32, outp.clone()));
+                       }
+                       self.counterparty_commitment_txn_on_chain.insert(commitment_txid, commitment_number);
 
                        log_trace!(logger, "Got broadcast of non-revoked counterparty commitment transaction {}", commitment_txid);
 
@@ -1652,7 +1461,7 @@ impl<ChanSigner: ChannelKeys> ChannelMonitor<ChanSigner> {
        }
 
        /// Attempts to claim a counterparty HTLC-Success/HTLC-Timeout's outputs using the revocation key
-       fn check_spend_counterparty_htlc<L: Deref>(&mut self, tx: &Transaction, commitment_number: u64, height: u32, logger: &L) -> (Vec<ClaimRequest>, Option<(Txid, Vec<TxOut>)>) where L::Target: Logger {
+       fn check_spend_counterparty_htlc<L: Deref>(&mut self, tx: &Transaction, commitment_number: u64, height: u32, logger: &L) -> (Vec<ClaimRequest>, Option<(Txid, Vec<(u32, TxOut)>)>) where L::Target: Logger {
                let htlc_txid = tx.txid();
                if tx.input.len() != 1 || tx.output.len() != 1 || tx.input[0].witness.len() != 5 {
                        return (Vec::new(), None)
@@ -1674,10 +1483,11 @@ impl<ChanSigner: ChannelKeys> ChannelMonitor<ChanSigner> {
                log_trace!(logger, "Counterparty HTLC broadcast {}:{}", htlc_txid, 0);
                let witness_data = InputMaterial::Revoked { per_commitment_point, counterparty_delayed_payment_base_key: self.counterparty_tx_cache.counterparty_delayed_payment_base_key, counterparty_htlc_base_key: self.counterparty_tx_cache.counterparty_htlc_base_key,  per_commitment_key, input_descriptor: InputDescriptors::RevokedOutput, amount: tx.output[0].value, htlc: None, on_counterparty_tx_csv: self.counterparty_tx_cache.on_counterparty_tx_csv };
                let claimable_outpoints = vec!(ClaimRequest { absolute_timelock: height + self.counterparty_tx_cache.on_counterparty_tx_csv as u32, aggregable: true, outpoint: BitcoinOutPoint { txid: htlc_txid, vout: 0}, witness_data });
-               (claimable_outpoints, Some((htlc_txid, tx.output.clone())))
+               let outputs = vec![(0, tx.output[0].clone())];
+               (claimable_outpoints, Some((htlc_txid, outputs)))
        }
 
-       fn broadcast_by_holder_state(&self, commitment_tx: &Transaction, holder_tx: &HolderSignedTx) -> (Vec<ClaimRequest>, Vec<TxOut>, Option<(Script, PublicKey, PublicKey)>) {
+       fn broadcast_by_holder_state(&self, commitment_tx: &Transaction, holder_tx: &HolderSignedTx) -> (Vec<ClaimRequest>, Vec<(u32, TxOut)>, Option<(Script, PublicKey, PublicKey)>) {
                let mut claim_requests = Vec::with_capacity(holder_tx.htlc_outputs.len());
                let mut watch_outputs = Vec::with_capacity(holder_tx.htlc_outputs.len());
 
@@ -1698,7 +1508,7 @@ impl<ChanSigner: ChannelKeys> ChannelMonitor<ChanSigner> {
                                                        } else { None },
                                                amount: htlc.amount_msat,
                                }});
-                               watch_outputs.push(commitment_tx.output[transaction_output_index as usize].clone());
+                               watch_outputs.push((transaction_output_index, commitment_tx.output[transaction_output_index as usize].clone()));
                        }
                }
 
@@ -1708,7 +1518,7 @@ impl<ChanSigner: ChannelKeys> ChannelMonitor<ChanSigner> {
        /// 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<L: Deref>(&mut self, tx: &Transaction, height: u32, logger: &L) -> (Vec<ClaimRequest>, (Txid, Vec<TxOut>)) where L::Target: Logger {
+       fn check_spend_holder_transaction<L: Deref>(&mut self, tx: &Transaction, height: u32, logger: &L) -> (Vec<ClaimRequest>, (Txid, Vec<(u32, TxOut)>)) where L::Target: Logger {
                let commitment_txid = tx.txid();
                let mut claim_requests = Vec::new();
                let mut watch_outputs = Vec::new();
@@ -1858,7 +1668,7 @@ impl<ChanSigner: ChannelKeys> ChannelMonitor<ChanSigner> {
        /// [`get_outputs_to_watch`].
        ///
        /// [`get_outputs_to_watch`]: #method.get_outputs_to_watch
-       pub fn block_connected<B: Deref, F: Deref, L: Deref>(&mut self, header: &BlockHeader, txdata: &TransactionData, height: u32, broadcaster: B, fee_estimator: F, logger: L)-> Vec<(Txid, Vec<TxOut>)>
+       pub fn block_connected<B: Deref, F: Deref, L: Deref>(&mut self, header: &BlockHeader, txdata: &TransactionData, height: u32, broadcaster: B, fee_estimator: F, logger: L)-> Vec<(Txid, Vec<(u32, TxOut)>)>
                where B::Target: BroadcasterInterface,
                      F::Target: FeeEstimator,
                                        L::Target: Logger,
@@ -1901,7 +1711,7 @@ impl<ChanSigner: ChannelKeys> ChannelMonitor<ChanSigner> {
                                                claimable_outpoints.append(&mut new_outpoints);
                                        }
                                } else {
-                                       if let Some(&(commitment_number, _)) = self.counterparty_commitment_txn_on_chain.get(&prevout.txid) {
+                                       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);
                                                claimable_outpoints.append(&mut new_outpoints);
                                                if let Some(new_outputs) = new_outputs_option {
@@ -1959,8 +1769,8 @@ impl<ChanSigner: ChannelKeys> ChannelMonitor<ChanSigner> {
                // Determine new outputs to watch by comparing against previously known outputs to watch,
                // updating the latter in the process.
                watch_outputs.retain(|&(ref txid, ref txouts)| {
-                       let output_scripts = txouts.iter().map(|o| o.script_pubkey.clone()).collect();
-                       self.outputs_to_watch.insert(txid.clone(), output_scripts).is_none()
+                       let idx_and_scripts = txouts.iter().map(|o| (o.0, o.1.script_pubkey.clone())).collect();
+                       self.outputs_to_watch.insert(txid.clone(), idx_and_scripts).is_none()
                });
                watch_outputs
        }
@@ -2009,8 +1819,8 @@ impl<ChanSigner: ChannelKeys> ChannelMonitor<ChanSigner> {
        fn spends_watched_output(&self, tx: &Transaction) -> bool {
                for input in tx.input.iter() {
                        if let Some(outputs) = self.get_outputs_to_watch().get(&input.previous_output.txid) {
-                               for (idx, _script_pubkey) in outputs.iter().enumerate() {
-                                       if idx == input.previous_output.vout as usize {
+                               for (idx, _script_pubkey) in outputs.iter() {
+                                       if *idx == input.previous_output.vout {
                                                return true;
                                        }
                                }
@@ -2393,12 +2203,7 @@ impl<ChanSigner: ChannelKeys + Readable> Readable for (BlockHash, ChannelMonitor
                for _ in 0..counterparty_commitment_txn_on_chain_len {
                        let txid: Txid = Readable::read(reader)?;
                        let commitment_number = <U48 as Readable>::read(reader)?.0;
-                       let outputs_count = <u64 as Readable>::read(reader)?;
-                       let mut outputs = Vec::with_capacity(cmp::min(outputs_count as usize, MAX_ALLOC_SIZE / 8));
-                       for _ in 0..outputs_count {
-                               outputs.push(Readable::read(reader)?);
-                       }
-                       if let Some(_) = counterparty_commitment_txn_on_chain.insert(txid, (commitment_number, outputs)) {
+                       if let Some(_) = counterparty_commitment_txn_on_chain.insert(txid, commitment_number) {
                                return Err(DecodeError::InvalidValue);
                        }
                }
@@ -2517,13 +2322,13 @@ impl<ChanSigner: ChannelKeys + Readable> Readable for (BlockHash, ChannelMonitor
                }
 
                let outputs_to_watch_len: u64 = Readable::read(reader)?;
-               let mut outputs_to_watch = HashMap::with_capacity(cmp::min(outputs_to_watch_len as usize, MAX_ALLOC_SIZE / (mem::size_of::<Txid>() + mem::size_of::<Vec<Script>>())));
+               let mut outputs_to_watch = HashMap::with_capacity(cmp::min(outputs_to_watch_len as usize, MAX_ALLOC_SIZE / (mem::size_of::<Txid>() + mem::size_of::<u32>() + mem::size_of::<Vec<Script>>())));
                for _ in 0..outputs_to_watch_len {
                        let txid = Readable::read(reader)?;
                        let outputs_len: u64 = Readable::read(reader)?;
-                       let mut outputs = Vec::with_capacity(cmp::min(outputs_len as usize, MAX_ALLOC_SIZE / mem::size_of::<Script>()));
+                       let mut outputs = Vec::with_capacity(cmp::min(outputs_len as usize, MAX_ALLOC_SIZE / (mem::size_of::<u32>() + mem::size_of::<Script>())));
                        for _ in 0..outputs_len {
-                               outputs.push(Readable::read(reader)?);
+                               outputs.push((Readable::read(reader)?, Readable::read(reader)?));
                        }
                        if let Some(_) = outputs_to_watch.insert(txid, outputs) {
                                return Err(DecodeError::InvalidValue);