Move TODO from `handle_monitor_update_res` into `Channel`

[rust-lightning] / lightning / src / ln / channel.rs

diff --git a/lightning/src/ln/channel.rs b/lightning/src/ln/channel.rs
index 73a1b56958c4a5f3f5814485d632eddbdb8ccf78..896c475049b4df56673dfa5e2c3ca7d45760e448 100644 (file)
--- a/lightning/src/ln/channel.rs
+++ b/lightning/src/ln/channel.rs
@@ -558,6 +558,11 @@ pub(super) struct Channel<Signer: ChannelSigner> {
        monitor_pending_channel_ready: bool,
        monitor_pending_revoke_and_ack: bool,
        monitor_pending_commitment_signed: bool,
+
+       // TODO: If a channel is drop'd, we don't know whether the `ChannelMonitor` is ultimately
+       // responsible for some of the HTLCs here or not - we don't know whether the update in question
+       // completed or not. We currently ignore these fields entirely when force-closing a channel,
+       // but need to handle this somehow or we run the risk of losing HTLCs!
        monitor_pending_forwards: Vec<(PendingHTLCInfo, u64)>,
        monitor_pending_failures: Vec<(HTLCSource, PaymentHash, HTLCFailReason)>,
        monitor_pending_finalized_fulfills: Vec<HTLCSource>,
@@ -743,6 +748,12 @@ pub(super) struct Channel<Signer: ChannelSigner> {
        /// The unique identifier used to re-derive the private key material for the channel through
        /// [`SignerProvider::derive_channel_signer`].
        channel_keys_id: [u8; 32],
+
+       /// When we generate [`ChannelMonitorUpdate`]s to persist, they may not be persisted immediately.
+       /// If we then persist the [`channelmanager::ChannelManager`] and crash before the persistence
+       /// completes we still need to be able to complete the persistence. Thus, we have to keep a
+       /// copy of the [`ChannelMonitorUpdate`] here until it is complete.
+       pending_monitor_updates: Vec<ChannelMonitorUpdate>,
 }
 
 #[cfg(any(test, fuzzing))]
@@ -1112,6 +1123,8 @@ impl<Signer: WriteableEcdsaChannelSigner> Channel<Signer> {
 
                        channel_type,
                        channel_keys_id,
+
+                       pending_monitor_updates: Vec::new(),
                })
        }
 
@@ -1458,6 +1471,8 @@ impl<Signer: WriteableEcdsaChannelSigner> Channel<Signer> {
 
                        channel_type,
                        channel_keys_id,
+
+                       pending_monitor_updates: Vec::new(),
                };
 
                Ok(chan)
@@ -4891,6 +4906,10 @@ impl<Signer: WriteableEcdsaChannelSigner> Channel<Signer> {
                (self.channel_state & ChannelState::MonitorUpdateInProgress as u32) != 0
        }
 
+       pub fn get_next_monitor_update(&self) -> Option<&ChannelMonitorUpdate> {
+               self.pending_monitor_updates.first()
+       }
+
        /// Returns true if funding_created was sent/received.
        pub fn is_funding_initiated(&self) -> bool {
                self.channel_state >= ChannelState::FundingSent as u32
@@ -6891,6 +6910,8 @@ impl<'a, 'b, 'c, ES: Deref, SP: Deref> ReadableArgs<(&'a ES, &'b SP, u32, &'c Ch
 
                        channel_type: channel_type.unwrap(),
                        channel_keys_id,
+
+                       pending_monitor_updates: Vec::new(),
                })
        }
 }