Rm ChannelMonitor merge capabilities in favor of explicit add/update
[rust-lightning] / lightning / src / ln / channelmonitor.rs
index f65b5e7f120ce983686ab9719d6fcbde6e8fcd7c..113e007abead2b6c647cab3db68ffe7363cf0217 100644 (file)
@@ -45,6 +45,45 @@ use std::sync::{Arc,Mutex};
 use std::{hash,cmp, mem};
 use std::ops::Deref;
 
+/// An update generated by the underlying Channel itself which contains some new information the
+/// ChannelMonitor should be made aware of.
+#[cfg_attr(test, derive(PartialEq))]
+#[derive(Clone)]
+#[must_use]
+pub struct ChannelMonitorUpdate {
+       pub(super) updates: Vec<ChannelMonitorUpdateStep>,
+       /// The sequence number of this update. Updates *must* be replayed in-order according to this
+       /// sequence number (and updates may panic if they are not). The update_id values are strictly
+       /// increasing and increase by one for each new update.
+       ///
+       /// This sequence number is also used to track up to which points updates which returned
+       /// ChannelMonitorUpdateErr::TemporaryFailure have been applied to all copies of a given
+       /// ChannelMonitor when ChannelManager::channel_monitor_updated is called.
+       pub update_id: u64,
+}
+
+impl Writeable for ChannelMonitorUpdate {
+       fn write<W: Writer>(&self, w: &mut W) -> Result<(), ::std::io::Error> {
+               self.update_id.write(w)?;
+               (self.updates.len() as u64).write(w)?;
+               for update_step in self.updates.iter() {
+                       update_step.write(w)?;
+               }
+               Ok(())
+       }
+}
+impl<R: ::std::io::Read> Readable<R> for ChannelMonitorUpdate {
+       fn read(r: &mut R) -> Result<Self, DecodeError> {
+               let update_id: u64 = Readable::read(r)?;
+               let len: u64 = Readable::read(r)?;
+               let mut updates = Vec::with_capacity(cmp::min(len as usize, MAX_ALLOC_SIZE / ::std::mem::size_of::<ChannelMonitorUpdateStep>()));
+               for _ in 0..len {
+                       updates.push(Readable::read(r)?);
+               }
+               Ok(Self { update_id, updates })
+       }
+}
+
 /// An error enum representing a failure to persist a channel monitor update.
 #[derive(Clone)]
 pub enum ChannelMonitorUpdateErr {
@@ -52,13 +91,13 @@ pub enum ChannelMonitorUpdateErr {
        /// 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 remote party.
-       /// ChannelManager::test_restore_channel_monitor can be used to retry the update(s) and restore
-       /// the channel to an operational state.
+       /// submitting new commitment transactions to the remote party. 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 continuing to operate when no copy of the updated ChannelMonitor could be
-       /// persisted is unsafe - if you failed to store the update on your own local disk you should
-       /// instead return PermanentFailure to force closure of the channel ASAP.
+       /// 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
@@ -69,8 +108,15 @@ pub enum ChannelMonitorUpdateErr {
        /// been "frozen".
        ///
        /// Note that even if updates made after TemporaryFailure succeed you must still call
-       /// test_restore_channel_monitor to ensure you have the latest monitor and re-enable normal
-       /// channel operation.
+       /// 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
@@ -85,9 +131,9 @@ pub enum ChannelMonitorUpdateErr {
 }
 
 /// General Err type for ChannelMonitor actions. Generally, this implies that the data provided is
-/// inconsistent with the ChannelMonitor being called. eg for ChannelMonitor::insert_combine this
-/// means you tried to merge two monitors for different channels or for a channel which was
-/// restored from a backup and then generated new commitment updates.
+/// 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
+/// corrupted.
 /// Contains a human-readable error message.
 #[derive(Debug)]
 pub struct MonitorUpdateError(pub &'static str);
@@ -104,7 +150,7 @@ impl_writeable!(HTLCUpdate, 0, { payment_hash, payment_preimage, source });
 
 /// Simple trait indicating ability to track a set of ChannelMonitors and multiplex events between
 /// them. Generally should be implemented by keeping a local SimpleManyChannelMonitor and passing
-/// events to it, while also taking any add_update_monitor events and passing them to some remote
+/// events to it, while also taking any add/update_monitor events and passing them to some remote
 /// server(s).
 ///
 /// Note that any updates to a channel's monitor *must* be applied to each instance of the
@@ -118,7 +164,7 @@ impl_writeable!(HTLCUpdate, 0, { payment_hash, payment_preimage, source });
 /// BlockNotifier and call the BlockNotifier's `block_(dis)connected` methods, which will notify
 /// all registered listeners in one go.
 pub trait ManyChannelMonitor<ChanSigner: ChannelKeys>: Send + Sync {
-       /// Adds or updates a monitor for the given `funding_txo`.
+       /// Adds a monitor for the given `funding_txo`.
        ///
        /// Implementer must also ensure that the funding_txo txid *and* outpoint are registered with
        /// any relevant ChainWatchInterfaces such that the provided monitor receives block_connected
@@ -129,8 +175,22 @@ pub trait ManyChannelMonitor<ChanSigner: ChannelKeys>: Send + Sync {
        /// any spends of any of the outputs.
        ///
        /// Any spends of outputs which should have been registered which aren't passed to
-       /// ChannelMonitors via block_connected may result in funds loss.
-       fn add_update_monitor(&self, funding_txo: OutPoint, monitor: ChannelMonitor<ChanSigner>) -> Result<(), ChannelMonitorUpdateErr>;
+       /// ChannelMonitors via block_connected may result in FUNDS LOSS.
+       fn add_monitor(&self, funding_txo: OutPoint, monitor: ChannelMonitor<ChanSigner>) -> Result<(), ChannelMonitorUpdateErr>;
+
+       /// Updates a monitor for the given `funding_txo`.
+       ///
+       /// Implementer must also ensure that the funding_txo txid *and* outpoint are registered with
+       /// any relevant ChainWatchInterfaces such that the provided monitor receives block_connected
+       /// callbacks with the funding transaction, or any spends of it.
+       ///
+       /// Further, the implementer must also ensure that each output returned in
+       /// monitor.get_watch_outputs() is registered to ensure that the provided monitor learns about
+       /// any spends of any of the outputs.
+       ///
+       /// Any spends of outputs which should have been registered which aren't passed to
+       /// ChannelMonitors via block_connected may result in FUNDS LOSS.
+       fn update_monitor(&self, funding_txo: OutPoint, monitor: ChannelMonitorUpdate) -> Result<(), ChannelMonitorUpdateErr>;
 
        /// Used by ChannelManager to get list of HTLC resolved onchain and which needed to be updated
        /// with success or failure.
@@ -219,14 +279,11 @@ impl<Key : Send + cmp::Eq + hash::Hash + 'static, ChanSigner: ChannelKeys, T: De
        }
 
        /// Adds or updates the monitor which monitors the channel referred to by the given key.
-       pub fn add_update_monitor_by_key(&self, key: Key, monitor: ChannelMonitor<ChanSigner>) -> Result<(), MonitorUpdateError> {
+       pub fn add_monitor_by_key(&self, key: Key, monitor: ChannelMonitor<ChanSigner>) -> Result<(), MonitorUpdateError> {
                let mut monitors = self.monitors.lock().unwrap();
-               match monitors.get_mut(&key) {
-                       Some(orig_monitor) => {
-                               log_trace!(self, "Updating Channel Monitor for channel {}", log_funding_info!(monitor.key_storage));
-                               return orig_monitor.insert_combine(monitor);
-                       },
-                       None => {}
+               let entry = match monitors.entry(key) {
+                       hash_map::Entry::Occupied(_) => return Err(MonitorUpdateError("Channel monitor for given key is already present")),
+                       hash_map::Entry::Vacant(e) => e,
                };
                match monitor.key_storage {
                        Storage::Local { ref funding_info, .. } => {
@@ -250,16 +307,35 @@ impl<Key : Send + cmp::Eq + hash::Hash + 'static, ChanSigner: ChannelKeys, T: De
                                self.chain_monitor.install_watch_outpoint((*txid, idx as u32), script);
                        }
                }
-               monitors.insert(key, monitor);
+               entry.insert(monitor);
                Ok(())
        }
+
+       /// Updates the monitor which monitors the channel referred to by the given key.
+       pub fn update_monitor_by_key(&self, key: Key, update: ChannelMonitorUpdate) -> Result<(), MonitorUpdateError> {
+               let mut monitors = self.monitors.lock().unwrap();
+               match monitors.get_mut(&key) {
+                       Some(orig_monitor) => {
+                               log_trace!(self, "Updating Channel Monitor for channel {}", log_funding_info!(orig_monitor.key_storage));
+                               orig_monitor.update_monitor(update)
+                       },
+                       None => Err(MonitorUpdateError("No such monitor registered"))
+               }
+       }
 }
 
 impl<ChanSigner: ChannelKeys, T: Deref + Sync + Send> ManyChannelMonitor<ChanSigner> for SimpleManyChannelMonitor<OutPoint, ChanSigner, T>
        where T::Target: BroadcasterInterface
 {
-       fn add_update_monitor(&self, funding_txo: OutPoint, monitor: ChannelMonitor<ChanSigner>) -> Result<(), ChannelMonitorUpdateErr> {
-               match self.add_update_monitor_by_key(funding_txo, monitor) {
+       fn add_monitor(&self, funding_txo: OutPoint, monitor: ChannelMonitor<ChanSigner>) -> Result<(), ChannelMonitorUpdateErr> {
+               match self.add_monitor_by_key(funding_txo, monitor) {
+                       Ok(_) => Ok(()),
+                       Err(_) => Err(ChannelMonitorUpdateErr::PermanentFailure),
+               }
+       }
+
+       fn update_monitor(&self, funding_txo: OutPoint, update: ChannelMonitorUpdate) -> Result<(), ChannelMonitorUpdateErr> {
+               match self.update_monitor_by_key(funding_txo, update) {
                        Ok(_) => Ok(()),
                        Err(_) => Err(ChannelMonitorUpdateErr::PermanentFailure),
                }
@@ -569,6 +645,141 @@ impl<R: ::std::io::Read> Readable<R> for ClaimTxBumpMaterial {
 const SERIALIZATION_VERSION: u8 = 1;
 const MIN_SERIALIZATION_VERSION: u8 = 1;
 
+#[cfg_attr(test, derive(PartialEq))]
+#[derive(Clone)]
+pub(super) enum ChannelMonitorUpdateStep {
+       LatestLocalCommitmentTXInfo {
+               // TODO: We really need to not be generating a fully-signed transaction in Channel and
+               // passing it here, we need to hold off so that the ChanSigner can enforce a
+               // only-sign-local-state-for-broadcast once invariant:
+               commitment_tx: LocalCommitmentTransaction,
+               local_keys: chan_utils::TxCreationKeys,
+               feerate_per_kw: u64,
+               htlc_outputs: Vec<(HTLCOutputInCommitment, Option<Signature>, Option<HTLCSource>)>,
+       },
+       LatestRemoteCommitmentTXInfo {
+               unsigned_commitment_tx: Transaction, // TODO: We should actually only need the txid here
+               htlc_outputs: Vec<(HTLCOutputInCommitment, Option<Box<HTLCSource>>)>,
+               commitment_number: u64,
+               their_revocation_point: PublicKey,
+       },
+       PaymentPreimage {
+               payment_preimage: PaymentPreimage,
+       },
+       CommitmentSecret {
+               idx: u64,
+               secret: [u8; 32],
+       },
+       /// Indicates our channel is likely a stale version, we're closing, but this update should
+       /// allow us to spend what is ours if our counterparty broadcasts their latest state.
+       RescueRemoteCommitmentTXInfo {
+               their_current_per_commitment_point: PublicKey,
+       },
+}
+
+impl Writeable for ChannelMonitorUpdateStep {
+       fn write<W: Writer>(&self, w: &mut W) -> Result<(), ::std::io::Error> {
+               match self {
+                       &ChannelMonitorUpdateStep::LatestLocalCommitmentTXInfo { ref commitment_tx, ref local_keys, ref feerate_per_kw, ref htlc_outputs } => {
+                               0u8.write(w)?;
+                               commitment_tx.write(w)?;
+                               local_keys.write(w)?;
+                               feerate_per_kw.write(w)?;
+                               (htlc_outputs.len() as u64).write(w)?;
+                               for &(ref output, ref signature, ref source) in htlc_outputs.iter() {
+                                       output.write(w)?;
+                                       signature.write(w)?;
+                                       source.write(w)?;
+                               }
+                       }
+                       &ChannelMonitorUpdateStep::LatestRemoteCommitmentTXInfo { ref unsigned_commitment_tx, ref htlc_outputs, ref commitment_number, ref their_revocation_point } => {
+                               1u8.write(w)?;
+                               unsigned_commitment_tx.write(w)?;
+                               commitment_number.write(w)?;
+                               their_revocation_point.write(w)?;
+                               (htlc_outputs.len() as u64).write(w)?;
+                               for &(ref output, ref source) in htlc_outputs.iter() {
+                                       output.write(w)?;
+                                       match source {
+                                               &None => 0u8.write(w)?,
+                                               &Some(ref s) => {
+                                                       1u8.write(w)?;
+                                                       s.write(w)?;
+                                               },
+                                       }
+                               }
+                       },
+                       &ChannelMonitorUpdateStep::PaymentPreimage { ref payment_preimage } => {
+                               2u8.write(w)?;
+                               payment_preimage.write(w)?;
+                       },
+                       &ChannelMonitorUpdateStep::CommitmentSecret { ref idx, ref secret } => {
+                               3u8.write(w)?;
+                               idx.write(w)?;
+                               secret.write(w)?;
+                       },
+                       &ChannelMonitorUpdateStep::RescueRemoteCommitmentTXInfo { ref their_current_per_commitment_point } => {
+                               4u8.write(w)?;
+                               their_current_per_commitment_point.write(w)?;
+                       },
+               }
+               Ok(())
+       }
+}
+impl<R: ::std::io::Read> Readable<R> for ChannelMonitorUpdateStep {
+       fn read(r: &mut R) -> Result<Self, DecodeError> {
+               match Readable::read(r)? {
+                       0u8 => {
+                               Ok(ChannelMonitorUpdateStep::LatestLocalCommitmentTXInfo {
+                                       commitment_tx: Readable::read(r)?,
+                                       local_keys: Readable::read(r)?,
+                                       feerate_per_kw: Readable::read(r)?,
+                                       htlc_outputs: {
+                                               let len: u64 = Readable::read(r)?;
+                                               let mut res = Vec::new();
+                                               for _ in 0..len {
+                                                       res.push((Readable::read(r)?, Readable::read(r)?, Readable::read(r)?));
+                                               }
+                                               res
+                                       },
+                               })
+                       },
+                       1u8 => {
+                               Ok(ChannelMonitorUpdateStep::LatestRemoteCommitmentTXInfo {
+                                       unsigned_commitment_tx: Readable::read(r)?,
+                                       commitment_number: Readable::read(r)?,
+                                       their_revocation_point: Readable::read(r)?,
+                                       htlc_outputs: {
+                                               let len: u64 = Readable::read(r)?;
+                                               let mut res = Vec::new();
+                                               for _ in 0..len {
+                                                       res.push((Readable::read(r)?, <Option<HTLCSource> as Readable<R>>::read(r)?.map(|o| Box::new(o))));
+                                               }
+                                               res
+                                       },
+                               })
+                       },
+                       2u8 => {
+                               Ok(ChannelMonitorUpdateStep::PaymentPreimage {
+                                       payment_preimage: Readable::read(r)?,
+                               })
+                       },
+                       3u8 => {
+                               Ok(ChannelMonitorUpdateStep::CommitmentSecret {
+                                       idx: Readable::read(r)?,
+                                       secret: Readable::read(r)?,
+                               })
+                       },
+                       4u8 => {
+                               Ok(ChannelMonitorUpdateStep::RescueRemoteCommitmentTXInfo {
+                                       their_current_per_commitment_point: Readable::read(r)?,
+                               })
+                       },
+                       _ => Err(DecodeError::InvalidValue),
+               }
+       }
+}
+
 /// A ChannelMonitor handles chain events (blocks connected and disconnected) and generates
 /// on-chain transactions to ensure no loss of funds occurs.
 ///
@@ -576,6 +787,7 @@ const MIN_SERIALIZATION_VERSION: u8 = 1;
 /// information and are actively monitoring the chain.
 #[derive(Clone)]
 pub struct ChannelMonitor<ChanSigner: ChannelKeys> {
+       latest_update_id: u64,
        commitment_transaction_number_obscure_factor: u64,
 
        key_storage: Storage<ChanSigner>,
@@ -664,7 +876,7 @@ pub struct ChannelMonitor<ChanSigner: ChannelKeys> {
 
        // We simply modify last_block_hash 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 insert_combine to ensure any local user copies keep
+       // (we do *not*, however, update them in update_monitor to ensure any local user copies keep
        // their last_block_hash from its state and not based on updated copies that didn't run through
        // the full block_connected).
        pub(crate) last_block_hash: Sha256dHash,
@@ -711,7 +923,8 @@ macro_rules! subtract_high_prio_fee {
 /// underlying object
 impl<ChanSigner: ChannelKeys> PartialEq for ChannelMonitor<ChanSigner> {
        fn eq(&self, other: &Self) -> bool {
-               if self.commitment_transaction_number_obscure_factor != other.commitment_transaction_number_obscure_factor ||
+               if self.latest_update_id != other.latest_update_id ||
+                       self.commitment_transaction_number_obscure_factor != other.commitment_transaction_number_obscure_factor ||
                        self.key_storage != other.key_storage ||
                        self.their_htlc_base_key != other.their_htlc_base_key ||
                        self.their_delayed_payment_base_key != other.their_delayed_payment_base_key ||
@@ -751,6 +964,8 @@ impl<ChanSigner: ChannelKeys + Writeable> ChannelMonitor<ChanSigner> {
                writer.write_all(&[SERIALIZATION_VERSION; 1])?;
                writer.write_all(&[MIN_SERIALIZATION_VERSION; 1])?;
 
+               self.latest_update_id.write(writer)?;
+
                // Set in initial Channel-object creation, so should always be set by now:
                U48(self.commitment_transaction_number_obscure_factor).write(writer)?;
 
@@ -997,30 +1212,43 @@ impl<ChanSigner: ChannelKeys + Writeable> ChannelMonitor<ChanSigner> {
 }
 
 impl<ChanSigner: ChannelKeys> ChannelMonitor<ChanSigner> {
-       pub(super) fn new(keys: ChanSigner, funding_key: &SecretKey, revocation_base_key: &SecretKey, delayed_payment_base_key: &SecretKey, htlc_base_key: &SecretKey, payment_base_key: &SecretKey, shutdown_pubkey: &PublicKey, our_to_self_delay: u16, destination_script: Script, logger: Arc<Logger>) -> ChannelMonitor<ChanSigner> {
+       pub(super) fn new(keys: ChanSigner, shutdown_pubkey: &PublicKey,
+                       our_to_self_delay: u16, destination_script: &Script, funding_info: (OutPoint, Script),
+                       their_htlc_base_key: &PublicKey, their_delayed_payment_base_key: &PublicKey,
+                       their_to_self_delay: u16, funding_redeemscript: Script, channel_value_satoshis: u64,
+                       commitment_transaction_number_obscure_factor: u64,
+                       logger: Arc<Logger>) -> ChannelMonitor<ChanSigner> {
+
+               assert!(commitment_transaction_number_obscure_factor <= (1 << 48));
+               let funding_key = keys.funding_key().clone();
+               let revocation_base_key = keys.revocation_base_key().clone();
+               let htlc_base_key = keys.htlc_base_key().clone();
+               let delayed_payment_base_key = keys.delayed_payment_base_key().clone();
+               let payment_base_key = keys.payment_base_key().clone();
                ChannelMonitor {
-                       commitment_transaction_number_obscure_factor: 0,
+                       latest_update_id: 0,
+                       commitment_transaction_number_obscure_factor,
 
                        key_storage: Storage::Local {
                                keys,
-                               funding_key: funding_key.clone(),
-                               revocation_base_key: revocation_base_key.clone(),
-                               htlc_base_key: htlc_base_key.clone(),
-                               delayed_payment_base_key: delayed_payment_base_key.clone(),
-                               payment_base_key: payment_base_key.clone(),
+                               funding_key,
+                               revocation_base_key,
+                               htlc_base_key,
+                               delayed_payment_base_key,
+                               payment_base_key,
                                shutdown_pubkey: shutdown_pubkey.clone(),
-                               funding_info: None,
+                               funding_info: Some(funding_info),
                                current_remote_commitment_txid: None,
                                prev_remote_commitment_txid: None,
                        },
-                       their_htlc_base_key: None,
-                       their_delayed_payment_base_key: None,
-                       funding_redeemscript: None,
-                       channel_value_satoshis: None,
+                       their_htlc_base_key: Some(their_htlc_base_key.clone()),
+                       their_delayed_payment_base_key: Some(their_delayed_payment_base_key.clone()),
+                       funding_redeemscript: Some(funding_redeemscript),
+                       channel_value_satoshis: Some(channel_value_satoshis),
                        their_cur_revocation_points: None,
 
                        our_to_self_delay: our_to_self_delay,
-                       their_to_self_delay: None,
+                       their_to_self_delay: Some(their_to_self_delay),
 
                        commitment_secrets: CounterpartyCommitmentSecrets::new(),
                        remote_claimable_outpoints: HashMap::new(),
@@ -1034,7 +1262,7 @@ impl<ChanSigner: ChannelKeys> ChannelMonitor<ChanSigner> {
                        payment_preimages: HashMap::new(),
                        pending_htlcs_updated: Vec::new(),
 
-                       destination_script: destination_script,
+                       destination_script: destination_script.clone(),
                        to_remote_rescue: None,
 
                        pending_claim_requests: HashMap::new(),
@@ -1207,8 +1435,10 @@ impl<ChanSigner: ChannelKeys> ChannelMonitor<ChanSigner> {
        /// is important that any clones of this channel monitor (including remote clones) by kept
        /// up-to-date as our local commitment transaction is updated.
        /// Panics if set_their_to_self_delay has never been called.
-       pub(super) fn provide_latest_local_commitment_tx_info(&mut self, commitment_tx: LocalCommitmentTransaction, local_keys: chan_utils::TxCreationKeys, feerate_per_kw: u64, htlc_outputs: Vec<(HTLCOutputInCommitment, Option<Signature>, Option<HTLCSource>)>) {
-               assert!(self.their_to_self_delay.is_some());
+       pub(super) fn provide_latest_local_commitment_tx_info(&mut self, commitment_tx: LocalCommitmentTransaction, local_keys: chan_utils::TxCreationKeys, feerate_per_kw: u64, htlc_outputs: Vec<(HTLCOutputInCommitment, Option<Signature>, Option<HTLCSource>)>) -> Result<(), MonitorUpdateError> {
+               if self.their_to_self_delay.is_none() {
+                       return Err(MonitorUpdateError("Got a local commitment tx info update before we'd set basic information about the channel"));
+               }
                self.prev_local_signed_commitment_tx = self.current_local_signed_commitment_tx.take();
                self.current_local_signed_commitment_tx = Some(LocalSignedTx {
                        txid: commitment_tx.txid(),
@@ -1221,6 +1451,7 @@ impl<ChanSigner: ChannelKeys> ChannelMonitor<ChanSigner> {
                        feerate_per_kw,
                        htlc_outputs,
                });
+               Ok(())
        }
 
        /// Provides a payment_hash->payment_preimage mapping. Will be automatically pruned when all
@@ -1229,95 +1460,56 @@ impl<ChanSigner: ChannelKeys> ChannelMonitor<ChanSigner> {
                self.payment_preimages.insert(payment_hash.clone(), payment_preimage.clone());
        }
 
-       /// Combines this ChannelMonitor with the information contained in the other ChannelMonitor.
-       /// After a successful call this ChannelMonitor is up-to-date and is safe to use to monitor the
-       /// chain for new blocks/transactions.
-       pub fn insert_combine(&mut self, mut other: ChannelMonitor<ChanSigner>) -> Result<(), MonitorUpdateError> {
-               match self.key_storage {
-                       Storage::Local { ref funding_info, .. } => {
-                               if funding_info.is_none() { return Err(MonitorUpdateError("Try to combine a Local monitor without funding_info")); }
-                               let our_funding_info = funding_info;
-                               if let Storage::Local { ref funding_info, .. } = other.key_storage {
-                                       if funding_info.is_none() { return Err(MonitorUpdateError("Try to combine a Local monitor without funding_info")); }
-                                       // We should be able to compare the entire funding_txo, but in fuzztarget it's trivially
-                                       // easy to collide the funding_txo hash and have a different scriptPubKey.
-                                       if funding_info.as_ref().unwrap().0 != our_funding_info.as_ref().unwrap().0 {
-                                               return Err(MonitorUpdateError("Funding transaction outputs are not identical!"));
-                                       }
-                               } else {
-                                       return Err(MonitorUpdateError("Try to combine a Local monitor with a Watchtower one !"));
-                               }
-                       },
-                       Storage::Watchtower { .. } => {
-                               if let Storage::Watchtower { .. } = other.key_storage {
-                                       unimplemented!();
-                               } else {
-                                       return Err(MonitorUpdateError("Try to combine a Watchtower monitor with a Local one !"));
-                               }
-                       },
-               }
-               let other_min_secret = other.get_min_seen_secret();
-               let our_min_secret = self.get_min_seen_secret();
-               if our_min_secret > other_min_secret {
-                       self.provide_secret(other_min_secret, other.get_secret(other_min_secret).unwrap())?;
-               }
-               if let Some(ref local_tx) = self.current_local_signed_commitment_tx {
-                       if let Some(ref other_local_tx) = other.current_local_signed_commitment_tx {
-                               let our_commitment_number = 0xffffffffffff - ((((local_tx.tx.without_valid_witness().input[0].sequence as u64 & 0xffffff) << 3*8) | (local_tx.tx.without_valid_witness().lock_time as u64 & 0xffffff)) ^ self.commitment_transaction_number_obscure_factor);
-                               let other_commitment_number = 0xffffffffffff - ((((other_local_tx.tx.without_valid_witness().input[0].sequence as u64 & 0xffffff) << 3*8) | (other_local_tx.tx.without_valid_witness().lock_time as u64 & 0xffffff)) ^ other.commitment_transaction_number_obscure_factor);
-                               if our_commitment_number >= other_commitment_number {
-                                       self.key_storage = other.key_storage;
-                               }
-                       }
-               }
-               // TODO: We should use current_remote_commitment_number and the commitment number out of
-               // local transactions to decide how to merge
-               if our_min_secret >= other_min_secret {
-                       self.their_cur_revocation_points = other.their_cur_revocation_points;
-                       for (txid, htlcs) in other.remote_claimable_outpoints.drain() {
-                               self.remote_claimable_outpoints.insert(txid, htlcs);
-                       }
-                       if let Some(local_tx) = other.prev_local_signed_commitment_tx {
-                               self.prev_local_signed_commitment_tx = Some(local_tx);
-                       }
-                       if let Some(local_tx) = other.current_local_signed_commitment_tx {
-                               self.current_local_signed_commitment_tx = Some(local_tx);
-                       }
-                       self.payment_preimages = other.payment_preimages;
-                       self.to_remote_rescue = other.to_remote_rescue;
-               }
-
-               self.current_remote_commitment_number = cmp::min(self.current_remote_commitment_number, other.current_remote_commitment_number);
+       /// Used in Channel to cheat wrt the update_ids since it plays games, will be removed soon!
+       pub(super) fn update_monitor_ooo(&mut self, mut updates: ChannelMonitorUpdate) -> Result<(), MonitorUpdateError> {
+               for update in updates.updates.drain(..) {
+                       match update {
+                               ChannelMonitorUpdateStep::LatestLocalCommitmentTXInfo { commitment_tx, local_keys, feerate_per_kw, htlc_outputs } =>
+                                       self.provide_latest_local_commitment_tx_info(commitment_tx, local_keys, feerate_per_kw, htlc_outputs)?,
+                               ChannelMonitorUpdateStep::LatestRemoteCommitmentTXInfo { unsigned_commitment_tx, htlc_outputs, commitment_number, their_revocation_point } =>
+                                       self.provide_latest_remote_commitment_tx_info(&unsigned_commitment_tx, htlc_outputs, commitment_number, their_revocation_point),
+                               ChannelMonitorUpdateStep::PaymentPreimage { payment_preimage } =>
+                                       self.provide_payment_preimage(&PaymentHash(Sha256::hash(&payment_preimage.0[..]).into_inner()), &payment_preimage),
+                               ChannelMonitorUpdateStep::CommitmentSecret { idx, secret } =>
+                                       self.provide_secret(idx, secret)?,
+                               ChannelMonitorUpdateStep::RescueRemoteCommitmentTXInfo { their_current_per_commitment_point } =>
+                                       self.provide_rescue_remote_commitment_tx_info(their_current_per_commitment_point),
+                       }
+               }
+               self.latest_update_id = updates.update_id;
                Ok(())
        }
 
-       /// Allows this monitor to scan only for transactions which are applicable. Note that this is
-       /// optional, without it this monitor cannot be used in an SPV client, but you may wish to
-       /// avoid this on a monitor you wish to send to a watchtower as it provides slightly better
-       /// privacy.
-       /// It's the responsibility of the caller to register outpoint and script with passing the former
-       /// value as key to add_update_monitor.
-       pub(super) fn set_funding_info(&mut self, new_funding_info: (OutPoint, Script)) {
-               match self.key_storage {
-                       Storage::Local { ref mut funding_info, .. } => {
-                               *funding_info = Some(new_funding_info);
-                       },
-                       Storage::Watchtower { .. } => {
-                               panic!("Channel somehow ended up with its internal ChannelMonitor being in Watchtower mode?");
-                       }
-               }
+       /// Updates a ChannelMonitor on the basis of some new information provided by the Channel
+       /// itself.
+       ///
+       /// panics if the given update is not the next update by update_id.
+       pub fn update_monitor(&mut self, mut updates: ChannelMonitorUpdate) -> Result<(), MonitorUpdateError> {
+               if self.latest_update_id + 1 != updates.update_id {
+                       panic!("Attempted to apply ChannelMonitorUpdates out of order, check the update_id before passing an update to update_monitor!");
+               }
+               for update in updates.updates.drain(..) {
+                       match update {
+                               ChannelMonitorUpdateStep::LatestLocalCommitmentTXInfo { commitment_tx, local_keys, feerate_per_kw, htlc_outputs } =>
+                                       self.provide_latest_local_commitment_tx_info(commitment_tx, local_keys, feerate_per_kw, htlc_outputs)?,
+                               ChannelMonitorUpdateStep::LatestRemoteCommitmentTXInfo { unsigned_commitment_tx, htlc_outputs, commitment_number, their_revocation_point } =>
+                                       self.provide_latest_remote_commitment_tx_info(&unsigned_commitment_tx, htlc_outputs, commitment_number, their_revocation_point),
+                               ChannelMonitorUpdateStep::PaymentPreimage { payment_preimage } =>
+                                       self.provide_payment_preimage(&PaymentHash(Sha256::hash(&payment_preimage.0[..]).into_inner()), &payment_preimage),
+                               ChannelMonitorUpdateStep::CommitmentSecret { idx, secret } =>
+                                       self.provide_secret(idx, secret)?,
+                               ChannelMonitorUpdateStep::RescueRemoteCommitmentTXInfo { their_current_per_commitment_point } =>
+                                       self.provide_rescue_remote_commitment_tx_info(their_current_per_commitment_point),
+                       }
+               }
+               self.latest_update_id = updates.update_id;
+               Ok(())
        }
 
-       /// We log these base keys at channel opening to being able to rebuild redeemscript in case of leaked revoked commit tx
-       /// Panics if commitment_transaction_number_obscure_factor doesn't fit in 48 bits
-       pub(super) fn set_basic_channel_info(&mut self, their_htlc_base_key: &PublicKey, their_delayed_payment_base_key: &PublicKey, their_to_self_delay: u16, funding_redeemscript: Script, channel_value_satoshis: u64, commitment_transaction_number_obscure_factor: u64) {
-               self.their_htlc_base_key = Some(their_htlc_base_key.clone());
-               self.their_delayed_payment_base_key = Some(their_delayed_payment_base_key.clone());
-               self.their_to_self_delay = Some(their_to_self_delay);
-               self.funding_redeemscript = Some(funding_redeemscript);
-               self.channel_value_satoshis = Some(channel_value_satoshis);
-               assert!(commitment_transaction_number_obscure_factor < (1 << 48));
-               self.commitment_transaction_number_obscure_factor = commitment_transaction_number_obscure_factor;
+       /// Gets the update_id from the latest ChannelMonitorUpdate which was applied to this
+       /// ChannelMonitor.
+       pub fn get_latest_update_id(&self) -> u64 {
+               self.latest_update_id
        }
 
        /// Gets the funding transaction outpoint of the channel this ChannelMonitor is monitoring for.
@@ -2981,6 +3173,7 @@ impl<R: ::std::io::Read, ChanSigner: ChannelKeys + Readable<R>> ReadableArgs<R,
                        return Err(DecodeError::UnknownVersion);
                }
 
+               let latest_update_id: u64 = Readable::read(reader)?;
                let commitment_transaction_number_obscure_factor = <U48 as Readable<R>>::read(reader)?.0;
 
                let key_storage = match <u8 as Readable<R>>::read(reader)? {
@@ -3241,6 +3434,7 @@ impl<R: ::std::io::Read, ChanSigner: ChannelKeys + Readable<R>> ReadableArgs<R,
                }
 
                Ok((last_block_hash.clone(), ChannelMonitor {
+                       latest_update_id,
                        commitment_transaction_number_obscure_factor,
 
                        key_storage,
@@ -3295,6 +3489,7 @@ mod tests {
        use bitcoin_hashes::sha256d::Hash as Sha256dHash;
        use bitcoin_hashes::hex::FromHex;
        use hex;
+       use chain::transaction::OutPoint;
        use ln::channelmanager::{PaymentPreimage, PaymentHash};
        use ln::channelmonitor::{ChannelMonitor, InputDescriptors};
        use ln::chan_utils;
@@ -3387,10 +3582,16 @@ mod tests {
 
                // Prune with one old state and a local commitment tx holding a few overlaps with the
                // old state.
-               let mut monitor = ChannelMonitor::new(keys, &SecretKey::from_slice(&[41; 32]).unwrap(), &SecretKey::from_slice(&[42; 32]).unwrap(), &SecretKey::from_slice(&[43; 32]).unwrap(), &SecretKey::from_slice(&[44; 32]).unwrap(), &SecretKey::from_slice(&[44; 32]).unwrap(), &PublicKey::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[45; 32]).unwrap()), 0, Script::new(), logger.clone());
+               let mut monitor = ChannelMonitor::new(keys,
+                       &PublicKey::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[42; 32]).unwrap()), 0, &Script::new(),
+                       (OutPoint { txid: Sha256dHash::from_slice(&[43; 32]).unwrap(), index: 0 }, Script::new()),
+                       &PublicKey::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[44; 32]).unwrap()),
+                       &PublicKey::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[45; 32]).unwrap()),
+                       0, Script::new(), 46, 0, logger.clone());
+
                monitor.their_to_self_delay = Some(10);
 
-               monitor.provide_latest_local_commitment_tx_info(LocalCommitmentTransaction::dummy(), dummy_keys!(), 0, preimages_to_local_htlcs!(preimages[0..10]));
+               monitor.provide_latest_local_commitment_tx_info(LocalCommitmentTransaction::dummy(), dummy_keys!(), 0, preimages_to_local_htlcs!(preimages[0..10])).unwrap();
                monitor.provide_latest_remote_commitment_tx_info(&dummy_tx, preimages_slice_to_htlc_outputs!(preimages[5..15]), 281474976710655, dummy_key);
                monitor.provide_latest_remote_commitment_tx_info(&dummy_tx, preimages_slice_to_htlc_outputs!(preimages[15..20]), 281474976710654, dummy_key);
                monitor.provide_latest_remote_commitment_tx_info(&dummy_tx, preimages_slice_to_htlc_outputs!(preimages[17..20]), 281474976710653, dummy_key);
@@ -3416,7 +3617,7 @@ mod tests {
 
                // Now update local commitment tx info, pruning only element 18 as we still care about the
                // previous commitment tx's preimages too
-               monitor.provide_latest_local_commitment_tx_info(LocalCommitmentTransaction::dummy(), dummy_keys!(), 0, preimages_to_local_htlcs!(preimages[0..5]));
+               monitor.provide_latest_local_commitment_tx_info(LocalCommitmentTransaction::dummy(), dummy_keys!(), 0, preimages_to_local_htlcs!(preimages[0..5])).unwrap();
                secret[0..32].clone_from_slice(&hex::decode("2273e227a5b7449b6e70f1fb4652864038b1cbf9cd7c043a7d6456b7fc275ad8").unwrap());
                monitor.provide_secret(281474976710653, secret.clone()).unwrap();
                assert_eq!(monitor.payment_preimages.len(), 12);
@@ -3424,7 +3625,7 @@ mod tests {
                test_preimages_exist!(&preimages[18..20], monitor);
 
                // But if we do it again, we'll prune 5-10
-               monitor.provide_latest_local_commitment_tx_info(LocalCommitmentTransaction::dummy(), dummy_keys!(), 0, preimages_to_local_htlcs!(preimages[0..3]));
+               monitor.provide_latest_local_commitment_tx_info(LocalCommitmentTransaction::dummy(), dummy_keys!(), 0, preimages_to_local_htlcs!(preimages[0..3])).unwrap();
                secret[0..32].clone_from_slice(&hex::decode("27cddaa5624534cb6cb9d7da077cf2b22ab21e9b506fd4998a51d54502e99116").unwrap());
                monitor.provide_secret(281474976710652, secret.clone()).unwrap();
                assert_eq!(monitor.payment_preimages.len(), 5);