From 28d9036ce4ac5858a48199bf1b8769939aca5c0d Mon Sep 17 00:00:00 2001
From: Valentine Wallace <vwallace@protonmail.com>
Date: Thu, 13 Aug 2020 14:35:39 -0400
Subject: [PATCH] Remove Channel's ChannelMonitor copy

---
 lightning/src/ln/channel.rs        | 35 ------------------------------
 lightning/src/ln/channelmonitor.rs | 23 +-------------------
 2 files changed, 1 insertion(+), 57 deletions(-)

diff --git a/lightning/src/ln/channel.rs b/lightning/src/ln/channel.rs
index 2bea55a57..9d4ccac89 100644
--- a/lightning/src/ln/channel.rs
+++ b/lightning/src/ln/channel.rs
@@ -386,9 +386,6 @@ pub(super) struct Channel<ChanSigner: ChannelKeys> {
 
 	their_shutdown_scriptpubkey: Option<Script>,
 
-	/// Used exclusively to broadcast the latest local state, mostly a historical quirk that this
-	/// is here:
-	channel_monitor: Option<ChannelMonitor<ChanSigner>>,
 	commitment_secrets: CounterpartyCommitmentSecrets,
 
 	network_sync: UpdateStatus,
@@ -557,7 +554,6 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 
 			their_shutdown_scriptpubkey: None,
 
-			channel_monitor: None,
 			commitment_secrets: CounterpartyCommitmentSecrets::new(),
 
 			network_sync: UpdateStatus::Fresh,
@@ -786,7 +782,6 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 
 			their_shutdown_scriptpubkey,
 
-			channel_monitor: None,
 			commitment_secrets: CounterpartyCommitmentSecrets::new(),
 
 			network_sync: UpdateStatus::Fresh,
@@ -1222,7 +1217,6 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 				payment_preimage: payment_preimage_arg.clone(),
 			}],
 		};
-		self.channel_monitor.as_mut().unwrap().update_monitor_ooo(monitor_update.clone(), logger).unwrap();
 
 		if (self.channel_state & (ChannelState::AwaitingRemoteRevoke as u32 | ChannelState::PeerDisconnected as u32 | ChannelState::MonitorUpdateFailed as u32)) != 0 {
 			for pending_update in self.holding_cell_htlc_updates.iter() {
@@ -1552,7 +1546,6 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 			} }
 		}
 
-		self.channel_monitor = Some(create_monitor!());
 		let channel_monitor = create_monitor!();
 
 		self.channel_state = ChannelState::FundingSent as u32;
@@ -1618,7 +1611,6 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 			} }
 		}
 
-		self.channel_monitor = Some(create_monitor!());
 		let channel_monitor = create_monitor!();
 
 		assert_eq!(self.channel_state & (ChannelState::MonitorUpdateFailed as u32), 0); // We have no had any monitor(s) yet to fail update!
@@ -2060,7 +2052,6 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 				htlc_outputs: htlcs_and_sigs
 			}]
 		};
-		self.channel_monitor.as_mut().unwrap().update_monitor_ooo(monitor_update.clone(), logger).unwrap();
 
 		for htlc in self.pending_inbound_htlcs.iter_mut() {
 			let new_forward = if let &InboundHTLCState::RemoteAnnounced(ref forward_info) = &htlc.state {
@@ -2280,7 +2271,6 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 				secret: msg.per_commitment_secret,
 			}],
 		};
-		self.channel_monitor.as_mut().unwrap().update_monitor_ooo(monitor_update.clone(), logger).unwrap();
 
 		// Update state now that we've passed all the can-fail calls...
 		// (note that we may still fail to generate the new commitment_signed message, but that's
@@ -3115,14 +3105,6 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 		self.user_id
 	}
 
-	/// May only be called after funding has been initiated (ie is_funding_initiated() is true)
-	pub fn channel_monitor(&mut self) -> &mut ChannelMonitor<ChanSigner> {
-		if self.channel_state < ChannelState::FundingSent as u32 {
-			panic!("Can't get a channel monitor until funding has been created");
-		}
-		self.channel_monitor.as_mut().unwrap()
-	}
-
 	/// Guaranteed to be Some after both FundingLocked messages have been exchanged (and, thus,
 	/// is_usable() returns true).
 	/// Allowed in any state (including after shutdown)
@@ -3397,9 +3379,6 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 		if header.bitcoin_hash() != self.last_block_connected {
 			self.last_block_connected = header.bitcoin_hash();
 			self.update_time_counter = cmp::max(self.update_time_counter, header.time);
-			if let Some(channel_monitor) = self.channel_monitor.as_mut() {
-				channel_monitor.last_block_hash = self.last_block_connected;
-			}
 			if self.funding_tx_confirmations > 0 {
 				if self.funding_tx_confirmations == self.minimum_depth as u64 {
 					let need_commitment_update = if non_shutdown_state == ChannelState::FundingSent as u32 {
@@ -3458,9 +3437,6 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 			self.funding_tx_confirmations = self.minimum_depth as u64 - 1;
 		}
 		self.last_block_connected = header.bitcoin_hash();
-		if let Some(channel_monitor) = self.channel_monitor.as_mut() {
-			channel_monitor.last_block_hash = self.last_block_connected;
-		}
 		false
 	}
 
@@ -3871,7 +3847,6 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 				their_revocation_point: self.their_cur_commitment_point.unwrap()
 			}]
 		};
-		self.channel_monitor.as_mut().unwrap().update_monitor_ooo(monitor_update.clone(), logger).unwrap();
 		self.channel_state |= ChannelState::AwaitingRemoteRevoke as u32;
 		Ok((res, monitor_update))
 	}
@@ -4242,8 +4217,6 @@ impl<ChanSigner: ChannelKeys + Writeable> Writeable for Channel<ChanSigner> {
 		self.their_shutdown_scriptpubkey.write(writer)?;
 
 		self.commitment_secrets.write(writer)?;
-
-		self.channel_monitor.as_ref().unwrap().write_for_disk(writer)?;
 		Ok(())
 	}
 }
@@ -4398,13 +4371,6 @@ impl<ChanSigner: ChannelKeys + Readable> Readable for Channel<ChanSigner> {
 		let their_shutdown_scriptpubkey = Readable::read(reader)?;
 		let commitment_secrets = Readable::read(reader)?;
 
-		let (monitor_last_block, channel_monitor) = Readable::read(reader)?;
-		// We drop the ChannelMonitor's last block connected hash cause we don't actually bother
-		// doing full block connection operations on the internal ChannelMonitor copies
-		if monitor_last_block != last_block_connected {
-			return Err(DecodeError::InvalidValue);
-		}
-
 		Ok(Channel {
 			user_id,
 
@@ -4476,7 +4442,6 @@ impl<ChanSigner: ChannelKeys + Readable> Readable for Channel<ChanSigner> {
 
 			their_shutdown_scriptpubkey,
 
-			channel_monitor: Some(channel_monitor),
 			commitment_secrets,
 
 			network_sync: UpdateStatus::Fresh,
diff --git a/lightning/src/ln/channelmonitor.rs b/lightning/src/ln/channelmonitor.rs
index b08bfddbf..060e88faa 100644
--- a/lightning/src/ln/channelmonitor.rs
+++ b/lightning/src/ln/channelmonitor.rs
@@ -828,7 +828,7 @@ pub struct ChannelMonitor<ChanSigner: ChannelKeys> {
 	// (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: BlockHash,
+	last_block_hash: BlockHash,
 	secp_ctx: Secp256k1<secp256k1::All>, //TODO: dedup this a bit...
 }
 
@@ -1370,27 +1370,6 @@ impl<ChanSigner: ChannelKeys> ChannelMonitor<ChanSigner> {
 		self.pending_monitor_events.push(MonitorEvent::CommitmentTxBroadcasted(self.funding_info.0));
 	}
 
-	/// Used in Channel to cheat wrt the update_ids since it plays games, will be removed soon!
-	pub(super) fn update_monitor_ooo<L: Deref>(&mut self, mut updates: ChannelMonitorUpdate, logger: &L) -> Result<(), MonitorUpdateError> where L::Target: Logger {
-		for update in updates.updates.drain(..) {
-			match update {
-				ChannelMonitorUpdateStep::LatestLocalCommitmentTXInfo { commitment_tx, htlc_outputs } => {
-					if self.lockdown_from_offchain { panic!(); }
-					self.provide_latest_local_commitment_tx_info(commitment_tx, 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, logger),
-				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::ChannelForceClosed { .. } => {},
-			}
-		}
-		self.latest_update_id = updates.update_id;
-		Ok(())
-	}
-
 	/// Updates a ChannelMonitor on the basis of some new information provided by the Channel
 	/// itself.
 	///
-- 
2.39.5