Merge pull request #1657 from TheBlueMatt/2022-08-async-man-update

[rust-lightning] / lightning / src / chain / channelmonitor.rs

diff --git a/lightning/src/chain/channelmonitor.rs b/lightning/src/chain/channelmonitor.rs
index 500f2b521dd404bdb5c53b06332c37fb5064a4c2..52cfe9972f7289388caa38d8b7244c7ec6b905bc 100644 (file)
--- a/lightning/src/chain/channelmonitor.rs
+++ b/lightning/src/chain/channelmonitor.rs
@@ -59,8 +59,13 @@ use core::convert::TryInto;
 use core::ops::Deref;
 use sync::Mutex;
 
-/// An update generated by the underlying Channel itself which contains some new information the
-/// ChannelMonitor should be made aware of.
+/// An update generated by the underlying channel itself which contains some new information the
+/// [`ChannelMonitor`] should be made aware of.
+///
+/// Because this represents only a small number of updates to the underlying state, it is generally
+/// much smaller than a full [`ChannelMonitor`]. However, for large single commitment transaction
+/// updates (e.g. ones during which there are hundreds of HTLCs pending on the commitment
+/// transaction), a single update may reach upwards of 1 MiB in serialized size.
 #[cfg_attr(any(test, fuzzing, feature = "_test_utils"), derive(PartialEq))]
 #[derive(Clone)]
 #[must_use]
@@ -578,14 +583,25 @@ pub enum Balance {
        /// 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.
+       MaybeTimeoutClaimableHTLC {
+               /// The amount potentially 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,
        },
+       /// HTLCs which we received from our counterparty which are claimable with a preimage which we
+       /// do not currently have. This will only be claimable if we receive the preimage from the node
+       /// to which we forwarded this HTLC before the timeout.
+       MaybePreimageClaimableHTLC {
+               /// The amount potentially 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 our counterparty will be able to claim the balance if we have not
+               /// yet received the preimage and claimed it ourselves.
+               expiry_height: u32,
+       },
        /// The channel has been closed, and our counterparty broadcasted a revoked commitment
        /// transaction.
        ///
@@ -1542,7 +1558,7 @@ impl<Signer: Sign> ChannelMonitorImpl<Signer> {
                                        confirmation_height: conf_thresh,
                                });
                        } else {
-                               return Some(Balance::MaybeClaimableHTLCAwaitingTimeout {
+                               return Some(Balance::MaybeTimeoutClaimableHTLC {
                                        claimable_amount_satoshis: htlc.amount_msat / 1000,
                                        claimable_height: htlc.cltv_expiry,
                                });
@@ -1565,6 +1581,11 @@ impl<Signer: Sign> ChannelMonitorImpl<Signer> {
                                        timeout_height: htlc.cltv_expiry,
                                });
                        }
+               } else if htlc_resolved.is_none() {
+                       return Some(Balance::MaybePreimageClaimableHTLC {
+                               claimable_amount_satoshis: htlc.amount_msat / 1000,
+                               expiry_height: htlc.cltv_expiry,
+                       });
                }
                None
        }
@@ -1722,12 +1743,19 @@ impl<Signer: Sign> ChannelMonitor<Signer> {
                        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 {
+                                       res.push(Balance::MaybeTimeoutClaimableHTLC {
                                                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;
+                               } else {
+                                       // As long as the HTLC is still in our latest commitment state, treat
+                                       // it as potentially claimable, even if it has long-since expired.
+                                       res.push(Balance::MaybePreimageClaimableHTLC {
+                                               claimable_amount_satoshis: htlc.amount_msat / 1000,
+                                               expiry_height: htlc.cltv_expiry,
+                                       });
                                }
                        }
                        res.push(Balance::ClaimableOnChannelClose {