Set AnchorDescriptor output value to CSV and P2A anchor amounts

Co-authored-by: Matt Corallo <git@bluematt.me>

Author: tankyleo

lightning/src/chain/channelmonitor.rs

@@ -4416,8 +4416,6 @@ impl<Signer: EcdsaChannelSigner> ChannelMonitorImpl<Signer> {
 						counterparty_node_id,
 						claim_id,
 						package_target_feerate_sat_per_1000_weight,
-						commitment_tx,
-						commitment_tx_fee_satoshis,
 						anchor_descriptor: AnchorDescriptor {
 							channel_derivation_parameters: ChannelDerivationParameters {
 								keys_id: self.channel_keys_id,
@@ -4428,8 +4426,11 @@ impl<Signer: EcdsaChannelSigner> ChannelMonitorImpl<Signer> {
 								txid: commitment_txid,
 								vout: anchor_output_idx,
 							},
+							value: commitment_tx.output[anchor_output_idx as usize].value,
 						},
 						pending_htlcs: pending_nondust_htlcs,
+						commitment_tx,
+						commitment_tx_fee_satoshis,
 					}));
 				},
 				ClaimEvent::BumpHTLC {

lightning/src/chain/onchaintx.rs

@@ -30,7 +30,8 @@ use crate::chain::package::{PackageSolvingData, PackageTemplate};
 use crate::chain::transaction::MaybeSignedTransaction;
 use crate::chain::ClaimId;
 use crate::ln::chan_utils::{
-	self, ChannelTransactionParameters, HTLCOutputInCommitment, HolderCommitmentTransaction,
+	get_keyed_anchor_redeemscript, shared_anchor_script_pubkey, ChannelTransactionParameters,
+	HTLCOutputInCommitment, HolderCommitmentTransaction,
 };
 use crate::ln::msgs::DecodeError;
 use crate::sign::{ecdsa::EcdsaChannelSigner, EntropySource, HTLCDescriptor, SignerProvider};
@@ -677,7 +678,16 @@ impl<ChannelSigner: EcdsaChannelSigner> OnchainTxHandler<ChannelSigner> {
 					let channel_parameters = output.channel_parameters.as_ref()
 						.unwrap_or(self.channel_parameters());
 					let funding_pubkey = &channel_parameters.holder_pubkeys.funding_pubkey;
-					match chan_utils::get_keyed_anchor_output(&tx, funding_pubkey) {
+					let script_pubkey = if channel_parameters.channel_type_features.supports_anchors_zero_fee_htlc_tx() {
+						get_keyed_anchor_redeemscript(funding_pubkey).to_p2wsh()
+					} else {
+						debug_assert!(channel_parameters.channel_type_features.supports_anchor_zero_fee_commitments());
+						shared_anchor_script_pubkey()
+					};
+					let anchor_output = tx.output.iter().enumerate()
+						.find(|(_, txout)| txout.script_pubkey == script_pubkey)
+						.map(|(idx, txout)| (idx as u32, txout));
+					match anchor_output {
 						// An anchor output was found, so we should yield a funding event externally.
 						Some((idx, _)) => {
 							// TODO: Use a lower confirmation target when both our and the

lightning/src/events/bump_transaction/mod.rs

@@ -26,7 +26,6 @@ use crate::ln::chan_utils::{
 	shared_anchor_script_pubkey, HTLCOutputInCommitment, ANCHOR_INPUT_WITNESS_WEIGHT,
 	HTLC_SUCCESS_INPUT_ANCHOR_WITNESS_WEIGHT, HTLC_TIMEOUT_INPUT_ANCHOR_WITNESS_WEIGHT,
 };
-use crate::ln::channel::ANCHOR_OUTPUT_VALUE_SATOSHI;
 use crate::ln::types::ChannelId;
 use crate::prelude::*;
 use crate::sign::ecdsa::EcdsaChannelSigner;
@@ -64,6 +63,8 @@ pub struct AnchorDescriptor {
 	/// The transaction input's outpoint corresponding to the commitment transaction's anchor
 	/// output.
 	pub outpoint: OutPoint,
+	/// Zero-fee-commitment anchors have variable value, which is tracked here.
+	pub value: Amount,
 }
 
 impl AnchorDescriptor {
@@ -80,7 +81,7 @@ impl AnchorDescriptor {
 			assert!(tx_params.channel_type_features.supports_anchor_zero_fee_commitments());
 			shared_anchor_script_pubkey()
 		};
-		TxOut { script_pubkey, value: Amount::from_sat(ANCHOR_OUTPUT_VALUE_SATOSHI) }
+		TxOut { script_pubkey, value: self.value }
 	}
 
 	/// Returns the unsigned transaction input spending the anchor output in the commitment
@@ -1029,6 +1030,7 @@ mod tests {
 	};
 	use crate::io::Cursor;
 	use crate::ln::chan_utils::ChannelTransactionParameters;
+	use crate::ln::channel::ANCHOR_OUTPUT_VALUE_SATOSHI;
 	use crate::sign::KeysManager;
 	use crate::types::features::ChannelTypeFeatures;
 	use crate::util::ser::Readable;
@@ -1147,6 +1149,7 @@ mod tests {
 					transaction_parameters,
 				},
 				outpoint: OutPoint { txid: Txid::from_byte_array([42; 32]), vout: 0 },
+				value: Amount::from_sat(ANCHOR_OUTPUT_VALUE_SATOSHI),
 			},
 			pending_htlcs: Vec::new(),
 		});

lightning/src/ln/chan_utils.rs

@@ -89,9 +89,6 @@ pub const ANCHOR_INPUT_WITNESS_WEIGHT: u64 = 114;
 #[cfg(not(feature = "grind_signatures"))]
 pub const ANCHOR_INPUT_WITNESS_WEIGHT: u64 = 115;
 
-/// The P2A scriptpubkey
-pub const P2A_SCRIPT: &[u8] = &[0x51, 0x02, 0x4e, 0x73];
-
 /// The maximum value of the P2A anchor
 pub const P2A_MAX_VALUE: u64 = 240;
 
@@ -978,16 +975,6 @@ pub fn get_keyed_anchor_redeemscript(funding_pubkey: &PublicKey) -> ScriptBuf {
 		.into_script()
 }
 
-/// Locates the output with a keyed anchor (non-zero-fee-commitments) script paying to
-/// `funding_pubkey` within `commitment_tx`.
-#[rustfmt::skip]
-pub(crate) fn get_keyed_anchor_output<'a>(commitment_tx: &'a Transaction, funding_pubkey: &PublicKey) -> Option<(u32, &'a TxOut)> {
-	let anchor_script = get_keyed_anchor_redeemscript(funding_pubkey).to_p2wsh();
-	commitment_tx.output.iter().enumerate()
-		.find(|(_, txout)| txout.script_pubkey == anchor_script)
-		.map(|(idx, txout)| (idx as u32, txout))
-}
-
 /// Returns the witness required to satisfy and spend a keyed anchor (non-zero-fee-commitments)
 /// input.
 pub fn build_keyed_anchor_input_witness(
@@ -1891,7 +1878,7 @@ impl CommitmentTransaction {
 				// These subtractions panic on underflow, but this should never happen
 				let trimmed_sum_sat = channel_value_satoshis - nondust_htlcs_value_sum_sat - to_broadcaster_value_sat - to_countersignatory_value_sat;
 				insert_non_htlc_output(TxOut {
-					script_pubkey: ScriptBuf::from_bytes(P2A_SCRIPT.to_vec()),
+					script_pubkey: shared_anchor_script_pubkey(),
 					value: cmp::min(Amount::from_sat(P2A_MAX_VALUE), trimmed_sum_sat),
 				});
 		}