Track HTLC resolving transaction to determine input index

diff --git a/lightning/src/chain/channelmonitor.rs b/lightning/src/chain/channelmonitor.rs
index 2be7f4cf1f52ebe0d49e8224514b05e07d2d69d0..522cdd87f981e8984c41bfa3c969366f3e347404 100644 (file)
--- a/lightning/src/chain/channelmonitor.rs
+++ b/lightning/src/chain/channelmonitor.rs
@@ -647,6 +647,7 @@ struct IrrevocablyResolvedHTLC {
        /// was not present in the confirmed commitment transaction), HTLC-Success, or HTLC-Timeout
        /// transaction.
        resolving_txid: Option<Txid>, // Added as optional, but always filled in, in 0.0.110
+       resolving_tx: Option<Transaction>,
        /// Only set if the HTLC claim was ours using a payment preimage
        payment_preimage: Option<PaymentPreimage>,
 }
@@ -662,6 +663,7 @@ impl Writeable for IrrevocablyResolvedHTLC {
                        (0, mapped_commitment_tx_output_idx, required),
                        (1, self.resolving_txid, option),
                        (2, self.payment_preimage, option),
+                       (3, self.resolving_tx, option),
                });
                Ok(())
        }
@@ -672,15 +674,18 @@ impl Readable for IrrevocablyResolvedHTLC {
                let mut mapped_commitment_tx_output_idx = 0;
                let mut resolving_txid = None;
                let mut payment_preimage = None;
+               let mut resolving_tx = None;
                read_tlv_fields!(reader, {
                        (0, mapped_commitment_tx_output_idx, required),
                        (1, resolving_txid, option),
                        (2, payment_preimage, option),
+                       (3, resolving_tx, option),
                });
                Ok(Self {
                        commitment_tx_output_idx: if mapped_commitment_tx_output_idx == u32::max_value() { None } else { Some(mapped_commitment_tx_output_idx) },
                        resolving_txid,
                        payment_preimage,
+                       resolving_tx,
                })
        }
 }
@@ -1526,6 +1531,7 @@ impl<Signer: Sign> ChannelMonitorImpl<Signer> {
                        if let Some(v) = htlc.transaction_output_index { v } else { return None; };
 
                let mut htlc_spend_txid_opt = None;
+               let mut htlc_spend_tx_opt = None;
                let mut holder_timeout_spend_pending = None;
                let mut htlc_spend_pending = None;
                let mut holder_delayed_output_pending = None;
@@ -1534,7 +1540,9 @@ impl<Signer: Sign> ChannelMonitorImpl<Signer> {
                                OnchainEvent::HTLCUpdate { commitment_tx_output_idx, htlc_value_satoshis, .. }
                                if commitment_tx_output_idx == Some(htlc_commitment_tx_output_idx) => {
                                        debug_assert!(htlc_spend_txid_opt.is_none());
-                                       htlc_spend_txid_opt = event.transaction.as_ref().map(|tx| tx.txid());
+                                       htlc_spend_txid_opt = Some(&event.txid);
+                                       debug_assert!(htlc_spend_tx_opt.is_none());
+                                       htlc_spend_tx_opt = event.transaction.as_ref();
                                        debug_assert!(holder_timeout_spend_pending.is_none());
                                        debug_assert_eq!(htlc_value_satoshis.unwrap(), htlc.amount_msat / 1000);
                                        holder_timeout_spend_pending = Some(event.confirmation_threshold());
@@ -1542,7 +1550,9 @@ impl<Signer: Sign> ChannelMonitorImpl<Signer> {
                                OnchainEvent::HTLCSpendConfirmation { commitment_tx_output_idx, preimage, .. }
                                if commitment_tx_output_idx == htlc_commitment_tx_output_idx => {
                                        debug_assert!(htlc_spend_txid_opt.is_none());
-                                       htlc_spend_txid_opt = event.transaction.as_ref().map(|tx| tx.txid());
+                                       htlc_spend_txid_opt = Some(&event.txid);
+                                       debug_assert!(htlc_spend_tx_opt.is_none());
+                                       htlc_spend_tx_opt = event.transaction.as_ref();
                                        debug_assert!(htlc_spend_pending.is_none());
                                        htlc_spend_pending = Some((event.confirmation_threshold(), preimage.is_some()));
                                },
@@ -1558,19 +1568,32 @@ impl<Signer: Sign> ChannelMonitorImpl<Signer> {
                let htlc_resolved = self.htlcs_resolved_on_chain.iter()
                        .find(|v| if v.commitment_tx_output_idx == Some(htlc_commitment_tx_output_idx) {
                                debug_assert!(htlc_spend_txid_opt.is_none());
-                               htlc_spend_txid_opt = v.resolving_txid;
+                               htlc_spend_txid_opt = v.resolving_txid.as_ref();
+                               debug_assert!(htlc_spend_tx_opt.is_none());
+                               htlc_spend_tx_opt = v.resolving_tx.as_ref();
                                true
                        } else { false });
                debug_assert!(holder_timeout_spend_pending.is_some() as u8 + htlc_spend_pending.is_some() as u8 + htlc_resolved.is_some() as u8 <= 1);
 
+               let htlc_commitment_outpoint = BitcoinOutPoint::new(confirmed_txid.unwrap(), htlc_commitment_tx_output_idx);
                let htlc_output_to_spend =
                        if let Some(txid) = htlc_spend_txid_opt {
-                               debug_assert!(
-                                       self.onchain_tx_handler.channel_transaction_parameters.opt_anchors.is_none(),
-                                       "This code needs updating for anchors");
-                               BitcoinOutPoint::new(txid, 0)
+                               // Because HTLC transactions either only have 1 input and 1 output (pre-anchors) or
+                               // are signed with SIGHASH_SINGLE|ANYONECANPAY under BIP-0143 (post-anchors), we can
+                               // locate the correct output by ensuring its adjacent input spends the HTLC output
+                               // in the commitment.
+                               if let Some(ref tx) = htlc_spend_tx_opt {
+                                       let htlc_input_idx_opt = tx.input.iter().enumerate()
+                                               .find(|(_, input)| input.previous_output == htlc_commitment_outpoint)
+                                               .map(|(idx, _)| idx as u32);
+                                       debug_assert!(htlc_input_idx_opt.is_some());
+                                       BitcoinOutPoint::new(*txid, htlc_input_idx_opt.unwrap_or(0))
+                               } else {
+                                       debug_assert!(!self.onchain_tx_handler.opt_anchors());
+                                       BitcoinOutPoint::new(*txid, 0)
+                               }
                        } else {
-                               BitcoinOutPoint::new(confirmed_txid.unwrap(), htlc_commitment_tx_output_idx)
+                               htlc_commitment_outpoint
                        };
                let htlc_output_spend_pending = self.onchain_tx_handler.is_output_spend_pending(&htlc_output_to_spend);
 
@@ -1594,8 +1617,7 @@ impl<Signer: Sign> ChannelMonitorImpl<Signer> {
                                } = &event.event {
                                        if event.transaction.as_ref().map(|tx| tx.input.iter().any(|inp| {
                                                if let Some(htlc_spend_txid) = htlc_spend_txid_opt {
-                                                       Some(tx.txid()) == htlc_spend_txid_opt ||
-                                                               inp.previous_output.txid == htlc_spend_txid
+                                                       tx.txid() == *htlc_spend_txid || inp.previous_output.txid == *htlc_spend_txid
                                                } else {
                                                        Some(inp.previous_output.txid) == confirmed_txid &&
                                                                inp.previous_output.vout == htlc_commitment_tx_output_idx
@@ -3074,7 +3096,9 @@ impl<Signer: Sign> ChannelMonitorImpl<Signer> {
                                                htlc_value_satoshis,
                                        }));
                                        self.htlcs_resolved_on_chain.push(IrrevocablyResolvedHTLC {
-                                               commitment_tx_output_idx, resolving_txid: Some(entry.txid),
+                                               commitment_tx_output_idx,
+                                               resolving_txid: Some(entry.txid),
+                                               resolving_tx: entry.transaction,
                                                payment_preimage: None,
                                        });
                                },
@@ -3087,7 +3111,9 @@ impl<Signer: Sign> ChannelMonitorImpl<Signer> {
                                },
                                OnchainEvent::HTLCSpendConfirmation { commitment_tx_output_idx, preimage, .. } => {
                                        self.htlcs_resolved_on_chain.push(IrrevocablyResolvedHTLC {
-                                               commitment_tx_output_idx: Some(commitment_tx_output_idx), resolving_txid: Some(entry.txid),
+                                               commitment_tx_output_idx: Some(commitment_tx_output_idx),
+                                               resolving_txid: Some(entry.txid),
+                                               resolving_tx: entry.transaction,
                                                payment_preimage: preimage,
                                        });
                                },

diff --git a/lightning/src/util/events.rs b/lightning/src/util/events.rs
index 28bd6978f6a5c9c7dad0563639e30a163bec5062..f7ec29e79e1898bc12e79594a43bc206f55f2791 100644 (file)
--- a/lightning/src/util/events.rs
+++ b/lightning/src/util/events.rs
@@ -249,7 +249,7 @@ pub enum BumpTransactionEvent {
        /// with additional inputs to meet the target feerate. Failure to meet the target feerate
        /// decreases the confirmation odds of the transaction package (which includes the commitment
        /// and child anchor transactions), possibly resulting in a loss of funds. Once the transaction
-       /// is constructed, it must be fully signed for and broadcasted by the consumer of the event
+       /// is constructed, it must be fully signed for and broadcast by the consumer of the event
        /// along with the `commitment_tx` enclosed. Note that the `commitment_tx` must always be
        /// broadcast first, as the child anchor transaction depends on it.
        ///