Add onchain_utils

Onchain_utils aims to gather interfaces to communicate between
onchain channel transactions parser (ChannelMonitor) and outputs
claiming logic (OnchainTxHandler). These interfaces are data
structures, generated per-case by ChannelMonitor and consumed
blindly by OnchainTxHandler.

Author: Antoine Riard

lightning/src/ln/channelmonitor.rs

@@ -31,7 +31,8 @@ use ln::msgs::DecodeError;
 use ln::chan_utils;
 use ln::chan_utils::{CounterpartyCommitmentSecrets, HTLCOutputInCommitment, LocalCommitmentTransaction, HTLCType};
 use ln::channelmanager::{HTLCSource, PaymentPreimage, PaymentHash};
-use ln::onchaintx::{OnchainTxHandler, InputDescriptors};
+use ln::onchaintx::OnchainTxHandler;
+use ln::onchain_utils::InputDescriptors;
 use chain::chaininterface::{ChainListener, ChainWatchInterface, BroadcasterInterface, FeeEstimator};
 use chain::transaction::OutPoint;
 use chain::keysinterface::{SpendableOutputDescriptor, ChannelKeys};
@@ -2538,7 +2539,8 @@ mod tests {
 	use chain::transaction::OutPoint;
 	use ln::channelmanager::{PaymentPreimage, PaymentHash};
 	use ln::channelmonitor::ChannelMonitor;
-	use ln::onchaintx::{OnchainTxHandler, InputDescriptors};
+	use ln::onchain_utils::InputDescriptors;
+	use ln::onchain_utils;
 	use ln::chan_utils;
 	use ln::chan_utils::{HTLCOutputInCommitment, LocalCommitmentTransaction};
 	use util::test_utils::TestLogger;
@@ -2731,7 +2733,7 @@ mod tests {
 		for (idx, inp) in claim_tx.input.iter_mut().zip(inputs_des.iter()).enumerate() {
 			sign_input!(sighash_parts, inp.0, idx as u32, 0, inp.1, sum_actual_sigs);
 		}
-		assert_eq!(base_weight + OnchainTxHandler::<InMemoryChannelKeys>::get_witnesses_weight(&inputs_des[..]),  claim_tx.get_weight() + /* max_length_sig */ (73 * inputs_des.len() - sum_actual_sigs));
+		assert_eq!(base_weight + onchain_utils::get_witnesses_weight(&inputs_des[..]),  claim_tx.get_weight() + /* max_length_sig */ (73 * inputs_des.len() - sum_actual_sigs));
 
 		// Claim tx with 1 offered HTLCs, 3 received HTLCs
 		claim_tx.input.clear();
@@ -2753,7 +2755,7 @@ mod tests {
 		for (idx, inp) in claim_tx.input.iter_mut().zip(inputs_des.iter()).enumerate() {
 			sign_input!(sighash_parts, inp.0, idx as u32, 0, inp.1, sum_actual_sigs);
 		}
-		assert_eq!(base_weight + OnchainTxHandler::<InMemoryChannelKeys>::get_witnesses_weight(&inputs_des[..]),  claim_tx.get_weight() + /* max_length_sig */ (73 * inputs_des.len() - sum_actual_sigs));
+		assert_eq!(base_weight + onchain_utils::get_witnesses_weight(&inputs_des[..]),  claim_tx.get_weight() + /* max_length_sig */ (73 * inputs_des.len() - sum_actual_sigs));
 
 		// Justice tx with 1 revoked HTLC-Success tx output
 		claim_tx.input.clear();
@@ -2773,7 +2775,7 @@ mod tests {
 		for (idx, inp) in claim_tx.input.iter_mut().zip(inputs_des.iter()).enumerate() {
 			sign_input!(sighash_parts, inp.0, idx as u32, 0, inp.1, sum_actual_sigs);
 		}
-		assert_eq!(base_weight + OnchainTxHandler::<InMemoryChannelKeys>::get_witnesses_weight(&inputs_des[..]), claim_tx.get_weight() + /* max_length_isg */ (73 * inputs_des.len() - sum_actual_sigs));
+		assert_eq!(base_weight + onchain_utils::get_witnesses_weight(&inputs_des[..]), claim_tx.get_weight() + /* max_length_isg */ (73 * inputs_des.len() - sum_actual_sigs));
 	}
 
 	// Further testing is done in the ChannelManager integration tests.

lightning/src/ln/mod.rs

@@ -23,6 +23,7 @@ pub mod peer_channel_encryptor;
 pub(crate) mod peer_channel_encryptor;
 
 mod channel;
+mod onchain_utils;
 mod onion_utils;
 mod wire;
 

lightning/src/ln/onchain_utils.rs

@@ -0,0 +1,90 @@
+//! Utilities for computing witnesses weight and feerate computation for onchain operation
+
+use ln::msgs::DecodeError;
+use util::ser::{Readable, Writer, Writeable};
+
+#[derive(PartialEq, Clone, Copy)]
+pub(crate) enum InputDescriptors {
+	RevokedOfferedHTLC,
+	RevokedReceivedHTLC,
+	OfferedHTLC,
+	ReceivedHTLC,
+	RevokedOutput, // either a revoked to_local output on commitment tx, a revoked HTLC-Timeout output or a revoked HTLC-Success output
+}
+
+impl Writeable for InputDescriptors {
+	fn write<W: Writer>(&self, writer: &mut W) -> Result<(), ::std::io::Error> {
+		match self {
+			&InputDescriptors::RevokedOfferedHTLC => {
+				writer.write_all(&[0; 1])?;
+			},
+			&InputDescriptors::RevokedReceivedHTLC => {
+				writer.write_all(&[1; 1])?;
+			},
+			&InputDescriptors::OfferedHTLC => {
+				writer.write_all(&[2; 1])?;
+			},
+			&InputDescriptors::ReceivedHTLC => {
+				writer.write_all(&[3; 1])?;
+			}
+			&InputDescriptors::RevokedOutput => {
+				writer.write_all(&[4; 1])?;
+			}
+		}
+		Ok(())
+	}
+}
+
+impl Readable for InputDescriptors {
+	fn read<R: ::std::io::Read>(reader: &mut R) -> Result<Self, DecodeError> {
+		let input_descriptor = match <u8 as Readable>::read(reader)? {
+			0 => {
+				InputDescriptors::RevokedOfferedHTLC
+			},
+			1 => {
+				InputDescriptors::RevokedReceivedHTLC
+			},
+			2 => {
+				InputDescriptors::OfferedHTLC
+			},
+			3 => {
+				InputDescriptors::ReceivedHTLC
+			},
+			4 => {
+				InputDescriptors::RevokedOutput
+			}
+			_ => return Err(DecodeError::InvalidValue),
+		};
+		Ok(input_descriptor)
+	}
+}
+
+pub(crate) fn get_witnesses_weight(inputs: &[InputDescriptors]) -> usize {
+	let mut tx_weight = 2; // count segwit flags
+	for inp in inputs {
+		// We use expected weight (and not actual) as signatures and time lock delays may vary
+		tx_weight +=  match inp {
+			// number_of_witness_elements + sig_length + revocation_sig + pubkey_length + revocationpubkey + witness_script_length + witness_script
+			&InputDescriptors::RevokedOfferedHTLC => {
+				1 + 1 + 73 + 1 + 33 + 1 + 133
+			},
+			// number_of_witness_elements + sig_length + revocation_sig + pubkey_length + revocationpubkey + witness_script_length + witness_script
+			&InputDescriptors::RevokedReceivedHTLC => {
+				1 + 1 + 73 + 1 + 33 + 1 + 139
+			},
+			// number_of_witness_elements + sig_length + remotehtlc_sig  + preimage_length + preimage + witness_script_length + witness_script
+			&InputDescriptors::OfferedHTLC => {
+				1 + 1 + 73 + 1 + 32 + 1 + 133
+			},
+			// number_of_witness_elements + sig_length + revocation_sig + pubkey_length + revocationpubkey + witness_script_length + witness_script
+			&InputDescriptors::ReceivedHTLC => {
+				1 + 1 + 73 + 1 + 1 + 1 + 139
+			},
+			// number_of_witness_elements + sig_length + revocation_sig + true_length + op_true + witness_script_length + witness_script
+			&InputDescriptors::RevokedOutput => {
+				1 + 1 + 73 + 1 + 1 + 1 + 77
+			},
+		};
+	}
+	tx_weight
+}

lightning/src/ln/onchaintx.rs

@@ -17,6 +17,8 @@ use ln::channelmonitor::{ANTI_REORG_DELAY, CLTV_SHARED_CLAIM_BUFFER, InputMateri
 use ln::channelmanager::PaymentPreimage;
 use ln::chan_utils;
 use ln::chan_utils::{TxCreationKeys, LocalCommitmentTransaction};
+use ln::onchain_utils::InputDescriptors;
+use ln::onchain_utils;
 use chain::chaininterface::{FeeEstimator, BroadcasterInterface, ConfirmationTarget, MIN_RELAY_FEE_SAT_PER_1000_WEIGHT};
 use chain::keysinterface::ChannelKeys;
 use util::logger::Logger;
@@ -92,61 +94,6 @@ impl Readable for ClaimTxBumpMaterial {
 	}
 }
 
-#[derive(PartialEq, Clone, Copy)]
-pub(crate) enum InputDescriptors {
-	RevokedOfferedHTLC,
-	RevokedReceivedHTLC,
-	OfferedHTLC,
-	ReceivedHTLC,
-	RevokedOutput, // either a revoked to_local output on commitment tx, a revoked HTLC-Timeout output or a revoked HTLC-Success output
-}
-
-impl Writeable for InputDescriptors {
-	fn write<W: Writer>(&self, writer: &mut W) -> Result<(), ::std::io::Error> {
-		match self {
-			&InputDescriptors::RevokedOfferedHTLC => {
-				writer.write_all(&[0; 1])?;
-			},
-			&InputDescriptors::RevokedReceivedHTLC => {
-				writer.write_all(&[1; 1])?;
-			},
-			&InputDescriptors::OfferedHTLC => {
-				writer.write_all(&[2; 1])?;
-			},
-			&InputDescriptors::ReceivedHTLC => {
-				writer.write_all(&[3; 1])?;
-			}
-			&InputDescriptors::RevokedOutput => {
-				writer.write_all(&[4; 1])?;
-			}
-		}
-		Ok(())
-	}
-}
-
-impl Readable for InputDescriptors {
-	fn read<R: ::std::io::Read>(reader: &mut R) -> Result<Self, DecodeError> {
-		let input_descriptor = match <u8 as Readable>::read(reader)? {
-			0 => {
-				InputDescriptors::RevokedOfferedHTLC
-			},
-			1 => {
-				InputDescriptors::RevokedReceivedHTLC
-			},
-			2 => {
-				InputDescriptors::OfferedHTLC
-			},
-			3 => {
-				InputDescriptors::ReceivedHTLC
-			},
-			4 => {
-				InputDescriptors::RevokedOutput
-			}
-			_ => return Err(DecodeError::InvalidValue),
-		};
-		Ok(input_descriptor)
-	}
-}
 
 macro_rules! subtract_high_prio_fee {
 	($logger: ident, $fee_estimator: expr, $value: expr, $predicted_weight: expr, $used_feerate: expr) => {
@@ -416,36 +363,6 @@ impl<ChanSigner: ChannelKeys> OnchainTxHandler<ChanSigner> {
 		}
 	}
 
-	pub(super) fn get_witnesses_weight(inputs: &[InputDescriptors]) -> usize {
-		let mut tx_weight = 2; // count segwit flags
-		for inp in inputs {
-			// We use expected weight (and not actual) as signatures and time lock delays may vary
-			tx_weight +=  match inp {
-				// number_of_witness_elements + sig_length + revocation_sig + pubkey_length + revocationpubkey + witness_script_length + witness_script
-				&InputDescriptors::RevokedOfferedHTLC => {
-					1 + 1 + 73 + 1 + 33 + 1 + 133
-				},
-				// number_of_witness_elements + sig_length + revocation_sig + pubkey_length + revocationpubkey + witness_script_length + witness_script
-				&InputDescriptors::RevokedReceivedHTLC => {
-					1 + 1 + 73 + 1 + 33 + 1 + 139
-				},
-				// number_of_witness_elements + sig_length + remotehtlc_sig  + preimage_length + preimage + witness_script_length + witness_script
-				&InputDescriptors::OfferedHTLC => {
-					1 + 1 + 73 + 1 + 32 + 1 + 133
-				},
-				// number_of_witness_elements + sig_length + revocation_sig + pubkey_length + revocationpubkey + witness_script_length + witness_script
-				&InputDescriptors::ReceivedHTLC => {
-					1 + 1 + 73 + 1 + 1 + 1 + 139
-				},
-				// number_of_witness_elements + sig_length + revocation_sig + true_length + op_true + witness_script_length + witness_script
-				&InputDescriptors::RevokedOutput => {
-					1 + 1 + 73 + 1 + 1 + 1 + 77
-				},
-			};
-		}
-		tx_weight
-	}
-
 	/// In LN, output claimed are time-sensitive, which means we have to spend them before reaching some timelock expiration. At in-channel
 	/// output detection, we generate a first version of a claim tx and associate to it a height timer. A height timer is an absolute block
 	/// height than once reached we should generate a new bumped "version" of the claim tx to be sure than we safely claim outputs before
@@ -535,11 +452,11 @@ impl<ChanSigner: ChannelKeys> OnchainTxHandler<ChanSigner> {
 		for per_outp_material in cached_claim_datas.per_input_material.values() {
 			match per_outp_material {
 				&InputMaterial::Revoked { ref input_descriptor, ref amount, .. } => {
-					inputs_witnesses_weight += Self::get_witnesses_weight(&[*input_descriptor]);
+					inputs_witnesses_weight += onchain_utils::get_witnesses_weight(&[*input_descriptor]);
 					amt += *amount;
 				},
 				&InputMaterial::RemoteHTLC { ref preimage, ref htlc, .. } => {
-					inputs_witnesses_weight += Self::get_witnesses_weight(if preimage.is_some() { &[InputDescriptors::OfferedHTLC] } else { &[InputDescriptors::ReceivedHTLC] });
+					inputs_witnesses_weight += onchain_utils::get_witnesses_weight(if preimage.is_some() { &[InputDescriptors::OfferedHTLC] } else { &[InputDescriptors::ReceivedHTLC] });
 					amt += htlc.amount_msat / 1000;
 				},
 				&InputMaterial::LocalHTLC { .. } => {