Avoid claiming remote received HTLCs with preimage
[rust-lightning] / src / ln / channelmonitor.rs
index f6d741afa10abfecfc64706ab13d6e2ae8a0bfed..9deb11073ffc31273d233277070f528c4eca478f 100644 (file)
@@ -456,12 +456,18 @@ pub struct ChannelMonitor {
        payment_preimages: HashMap<PaymentHash, PaymentPreimage>,
 
        destination_script: Script,
+       // Thanks to data loss protection, we may be able to claim our non-htlc funds
+       // back, this is the script we have to spend from but we need to
+       // scan every commitment transaction for that
+       to_remote_rescue: Option<(Script, SecretKey)>,
 
        // Used to track outpoint in the process of being claimed by our transactions. We need to scan all transactions
        // for inputs spending this. If height timer (u32) is expired and claim tx hasn't reached enough confirmations
        // before, use TxMaterial to regenerate a new claim tx with a satoshis-per-1000-weight-units higher than last
-       // one (u64).
-       our_claim_txn_waiting_first_conf: HashMap<BitcoinOutPoint, (u32, TxMaterial, u64)>,
+       // one (u64), if timelock expiration (u32) is near, decrease height timer, the in-between bumps delay.
+       // Last field cached (u32) is height of outpoint confirmation, which is needed to flush this tracker
+       // in case of reorgs, given block timer are scaled on timer expiration we can't deduce from it original height.
+       our_claim_txn_waiting_first_conf: HashMap<BitcoinOutPoint, (u32, TxMaterial, u64, u32, u32)>,
 
        // Used to track onchain events, i.e transactions parts of channels confirmed on chain, on which
        // we have to take actions once they reach enough confs. Key is a block height timer, i.e we enforce
@@ -482,13 +488,13 @@ macro_rules! subtract_high_prio_fee {
        ($self: ident, $fee_estimator: expr, $value: expr, $predicted_weight: expr, $spent_txid: expr, $used_feerate: expr) => {
                {
                        $used_feerate = $fee_estimator.get_est_sat_per_1000_weight(ConfirmationTarget::HighPriority);
-                       let mut fee = $used_feerate * $predicted_weight / 1000;
+                       let mut fee = $used_feerate * ($predicted_weight as u64) / 1000;
                        if $value <= fee {
                                $used_feerate = $fee_estimator.get_est_sat_per_1000_weight(ConfirmationTarget::Normal);
-                               fee = $used_feerate * $predicted_weight / 1000;
+                               fee = $used_feerate * ($predicted_weight as u64) / 1000;
                                if $value <= fee {
                                        $used_feerate = $fee_estimator.get_est_sat_per_1000_weight(ConfirmationTarget::Background);
-                                       fee = $used_feerate * $predicted_weight / 1000;
+                                       fee = $used_feerate * ($predicted_weight as u64) / 1000;
                                        if $value <= fee {
                                                log_error!($self, "Failed to generate an on-chain punishment tx spending {} as even low priority fee ({} sat) was more than the entire claim balance ({} sat)",
                                                        $spent_txid, fee, $value);
@@ -533,6 +539,7 @@ impl PartialEq for ChannelMonitor {
                        self.current_local_signed_commitment_tx != other.current_local_signed_commitment_tx ||
                        self.payment_preimages != other.payment_preimages ||
                        self.destination_script != other.destination_script ||
+                       self.to_remote_rescue != other.to_remote_rescue ||
                        self.our_claim_txn_waiting_first_conf != other.our_claim_txn_waiting_first_conf ||
                        self.onchain_events_waiting_threshold_conf != other.onchain_events_waiting_threshold_conf
                {
@@ -583,6 +590,7 @@ impl ChannelMonitor {
 
                        payment_preimages: HashMap::new(),
                        destination_script: destination_script,
+                       to_remote_rescue: None,
 
                        our_claim_txn_waiting_first_conf: HashMap::new(),
 
@@ -594,7 +602,7 @@ impl ChannelMonitor {
                }
        }
 
-       fn get_witnesses_weight(inputs: &[InputDescriptors]) -> u64 {
+       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
@@ -624,6 +632,15 @@ impl ChannelMonitor {
                tx_weight
        }
 
+       fn get_height_timer(current_height: u32, timelock_expiration: u32) -> u32 {
+               if timelock_expiration <= current_height || timelock_expiration - current_height <= 3 {
+                       return current_height + 1
+               } else if timelock_expiration - current_height <= 15 {
+                       return current_height + 3
+               }
+               current_height + 15
+       }
+
        #[inline]
        fn place_secret(idx: u64) -> u8 {
                for i in 0..48 {
@@ -752,6 +769,22 @@ impl ChannelMonitor {
                }
        }
 
+       pub(super) fn provide_rescue_remote_commitment_tx_info(&mut self, their_revocation_point: PublicKey) {
+               match self.key_storage {
+                       Storage::Local { ref payment_base_key, .. } => {
+                               if let Ok(payment_key) = chan_utils::derive_public_key(&self.secp_ctx, &their_revocation_point, &PublicKey::from_secret_key(&self.secp_ctx, &payment_base_key)) {
+                                       let to_remote_script =  Builder::new().push_opcode(opcodes::all::OP_PUSHBYTES_0)
+                                               .push_slice(&Hash160::hash(&payment_key.serialize())[..])
+                                               .into_script();
+                                       if let Ok(to_remote_key) = chan_utils::derive_private_key(&self.secp_ctx, &their_revocation_point, &payment_base_key) {
+                                               self.to_remote_rescue = Some((to_remote_script, to_remote_key));
+                                       }
+                               }
+                       },
+                       Storage::Watchtower { .. } => {}
+               }
+       }
+
        /// Informs this monitor of the latest local (ie broadcastable) commitment transaction. The
        /// monitor watches for timeouts and may broadcast it if we approach such a timeout. Thus, it
        /// is important that any clones of this channel monitor (including remote clones) by kept
@@ -841,6 +874,7 @@ impl ChannelMonitor {
                                self.current_local_signed_commitment_tx = Some(local_tx);
                        }
                        self.payment_preimages = other.payment_preimages;
+                       self.to_remote_rescue = other.to_remote_rescue;
                }
 
                self.current_remote_commitment_number = cmp::min(self.current_remote_commitment_number, other.current_remote_commitment_number);
@@ -1094,6 +1128,13 @@ impl ChannelMonitor {
 
                self.last_block_hash.write(writer)?;
                self.destination_script.write(writer)?;
+               if let Some((ref to_remote_script, ref local_key)) = self.to_remote_rescue {
+                       writer.write_all(&[1; 1])?;
+                       to_remote_script.write(writer)?;
+                       local_key.write(writer)?;
+               } else {
+                       writer.write_all(&[0; 1])?;
+               }
 
                writer.write_all(&byte_utils::be64_to_array(self.our_claim_txn_waiting_first_conf.len() as u64))?;
                for (ref outpoint, claim_tx_data) in self.our_claim_txn_waiting_first_conf.iter() {
@@ -1129,6 +1170,8 @@ impl ChannelMonitor {
                                }
                        }
                        writer.write_all(&byte_utils::be64_to_array(claim_tx_data.2))?;
+                       writer.write_all(&byte_utils::be32_to_array(claim_tx_data.3))?;
+                       writer.write_all(&byte_utils::be32_to_array(claim_tx_data.4))?;
                }
 
                writer.write_all(&byte_utils::be64_to_array(self.onchain_events_waiting_threshold_conf.len() as u64))?;
@@ -1283,7 +1326,7 @@ impl ChannelMonitor {
                                                witness: Vec::new(),
                                        });
                                        inputs_desc.push(InputDescriptors::RevokedOutput);
-                                       inputs_info.push((None, outp.value));
+                                       inputs_info.push((None, outp.value, self.our_to_self_delay as u32));
                                        total_value += outp.value;
                                } else if Some(&outp.script_pubkey) == local_payment_p2wpkh.as_ref() {
                                        spendable_outputs.push(SpendableOutputDescriptor::DynamicOutputP2WPKH {
@@ -1347,7 +1390,7 @@ impl ChannelMonitor {
                                                if htlc.cltv_expiry > height + CLTV_SHARED_CLAIM_BUFFER {
                                                        inputs.push(input);
                                                        inputs_desc.push(if htlc.offered { InputDescriptors::RevokedOfferedHTLC } else { InputDescriptors::RevokedReceivedHTLC });
-                                                       inputs_info.push((Some(idx), tx.output[transaction_output_index as usize].value));
+                                                       inputs_info.push((Some(idx), tx.output[transaction_output_index as usize].value, htlc.cltv_expiry));
                                                        total_value += tx.output[transaction_output_index as usize].value;
                                                } else {
                                                        let mut single_htlc_tx = Transaction {
@@ -1360,6 +1403,7 @@ impl ChannelMonitor {
                                                                }),
                                                        };
                                                        let predicted_weight = single_htlc_tx.get_weight() + Self::get_witnesses_weight(&[if htlc.offered { InputDescriptors::RevokedOfferedHTLC } else { InputDescriptors::RevokedReceivedHTLC }]);
+                                                       let height_timer = Self::get_height_timer(height, htlc.cltv_expiry);
                                                        let mut used_feerate;
                                                        if subtract_high_prio_fee!(self, fee_estimator, single_htlc_tx.output[0].value, predicted_weight, tx.txid(), used_feerate) {
                                                                let sighash_parts = bip143::SighashComponents::new(&single_htlc_tx);
@@ -1367,7 +1411,7 @@ impl ChannelMonitor {
                                                                assert!(predicted_weight >= single_htlc_tx.get_weight());
                                                                match self.our_claim_txn_waiting_first_conf.entry(single_htlc_tx.input[0].previous_output.clone()) {
                                                                        hash_map::Entry::Occupied(_) => {},
-                                                                       hash_map::Entry::Vacant(entry) => { entry.insert((height + 3, TxMaterial::Revoked { script: redeemscript, pubkey: Some(revocation_pubkey), key: revocation_key, is_htlc: true, amount: htlc.amount_msat / 1000 }, used_feerate)); }
+                                                                       hash_map::Entry::Vacant(entry) => { entry.insert((height_timer, TxMaterial::Revoked { script: redeemscript, pubkey: Some(revocation_pubkey), key: revocation_key, is_htlc: true, amount: htlc.amount_msat / 1000 }, used_feerate, htlc.cltv_expiry, height)); }
                                                                }
                                                                txn_to_broadcast.push(single_htlc_tx);
                                                        }
@@ -1444,9 +1488,10 @@ impl ChannelMonitor {
 
                        for (input, info) in spend_tx.input.iter_mut().zip(inputs_info.iter()) {
                                let (redeemscript, revocation_key) = sign_input!(sighash_parts, input, info.0, info.1);
+                               let height_timer = Self::get_height_timer(height, info.2);
                                match self.our_claim_txn_waiting_first_conf.entry(input.previous_output.clone()) {
                                        hash_map::Entry::Occupied(_) => {},
-                                       hash_map::Entry::Vacant(entry) => { entry.insert((height + 3, TxMaterial::Revoked { script: redeemscript, pubkey: if info.0.is_some() { Some(revocation_pubkey) } else { None }, key: revocation_key, is_htlc: if info.0.is_some() { true } else { false }, amount: info.1 }, used_feerate)); }
+                                       hash_map::Entry::Vacant(entry) => { entry.insert((height_timer, TxMaterial::Revoked { script: redeemscript, pubkey: if info.0.is_some() { Some(revocation_pubkey) } else { None }, key: revocation_key, is_htlc: if info.0.is_some() { true } else { false }, amount: info.1 }, used_feerate, if !info.0.is_some() { height + info.2 } else { info.2 }, height)); }
                                }
                        }
                        assert!(predicted_weight >= spend_tx.get_weight());
@@ -1598,45 +1643,48 @@ impl ChannelMonitor {
                                                                return (txn_to_broadcast, (commitment_txid, watch_outputs), spendable_outputs); // Corrupted per_commitment_data, fuck this user
                                                        }
                                                        if let Some(payment_preimage) = self.payment_preimages.get(&htlc.payment_hash) {
-                                                               let input = TxIn {
-                                                                       previous_output: BitcoinOutPoint {
-                                                                               txid: commitment_txid,
-                                                                               vout: transaction_output_index,
-                                                                       },
-                                                                       script_sig: Script::new(),
-                                                                       sequence: idx as u32, // reset to 0xfffffffd in sign_input
-                                                                       witness: Vec::new(),
-                                                               };
-                                                               if htlc.cltv_expiry > height + CLTV_SHARED_CLAIM_BUFFER {
-                                                                       inputs.push(input);
-                                                                       inputs_desc.push(if htlc.offered { InputDescriptors::OfferedHTLC } else { InputDescriptors::ReceivedHTLC });
-                                                                       inputs_info.push((payment_preimage, tx.output[transaction_output_index as usize].value));
-                                                                       total_value += tx.output[transaction_output_index as usize].value;
-                                                               } else {
-                                                                       let mut single_htlc_tx = Transaction {
-                                                                               version: 2,
-                                                                               lock_time: 0,
-                                                                               input: vec![input],
-                                                                               output: vec!(TxOut {
-                                                                                       script_pubkey: self.destination_script.clone(),
-                                                                                       value: htlc.amount_msat / 1000,
-                                                                               }),
+                                                               if htlc.offered {
+                                                                       let input = TxIn {
+                                                                               previous_output: BitcoinOutPoint {
+                                                                                       txid: commitment_txid,
+                                                                                       vout: transaction_output_index,
+                                                                               },
+                                                                               script_sig: Script::new(),
+                                                                               sequence: idx as u32, // reset to 0xfffffffd in sign_input
+                                                                               witness: Vec::new(),
                                                                        };
-                                                                       let predicted_weight = single_htlc_tx.get_weight() + Self::get_witnesses_weight(&[if htlc.offered { InputDescriptors::OfferedHTLC } else { InputDescriptors::ReceivedHTLC }]);
-                                                                       let mut used_feerate;
-                                                                       if subtract_high_prio_fee!(self, fee_estimator, single_htlc_tx.output[0].value, predicted_weight, tx.txid(), used_feerate) {
-                                                                               let sighash_parts = bip143::SighashComponents::new(&single_htlc_tx);
-                                                                               let (redeemscript, htlc_key) = sign_input!(sighash_parts, single_htlc_tx.input[0], htlc.amount_msat / 1000, payment_preimage.0.to_vec());
-                                                                               assert!(predicted_weight >= single_htlc_tx.get_weight());
-                                                                               spendable_outputs.push(SpendableOutputDescriptor::StaticOutput {
-                                                                                       outpoint: BitcoinOutPoint { txid: single_htlc_tx.txid(), vout: 0 },
-                                                                                       output: single_htlc_tx.output[0].clone(),
-                                                                               });
-                                                                               match self.our_claim_txn_waiting_first_conf.entry(single_htlc_tx.input[0].previous_output.clone()) {
-                                                                                       hash_map::Entry::Occupied(_) => {},
-                                                                                       hash_map::Entry::Vacant(entry) => { entry.insert((height + 3, TxMaterial::RemoteHTLC { script: redeemscript, key: htlc_key, preimage: Some(*payment_preimage), amount: htlc.amount_msat / 1000 }, used_feerate)); }
+                                                                       if htlc.cltv_expiry > height + CLTV_SHARED_CLAIM_BUFFER {
+                                                                               inputs.push(input);
+                                                                               inputs_desc.push(if htlc.offered { InputDescriptors::OfferedHTLC } else { InputDescriptors::ReceivedHTLC });
+                                                                               inputs_info.push((payment_preimage, tx.output[transaction_output_index as usize].value, htlc.cltv_expiry));
+                                                                               total_value += tx.output[transaction_output_index as usize].value;
+                                                                       } else {
+                                                                               let mut single_htlc_tx = Transaction {
+                                                                                       version: 2,
+                                                                                       lock_time: 0,
+                                                                                       input: vec![input],
+                                                                                       output: vec!(TxOut {
+                                                                                               script_pubkey: self.destination_script.clone(),
+                                                                                               value: htlc.amount_msat / 1000,
+                                                                                       }),
+                                                                               };
+                                                                               let predicted_weight = single_htlc_tx.get_weight() + Self::get_witnesses_weight(&[if htlc.offered { InputDescriptors::OfferedHTLC } else { InputDescriptors::ReceivedHTLC }]);
+                                                                               let height_timer = Self::get_height_timer(height, htlc.cltv_expiry);
+                                                                               let mut used_feerate;
+                                                                               if subtract_high_prio_fee!(self, fee_estimator, single_htlc_tx.output[0].value, predicted_weight, tx.txid(), used_feerate) {
+                                                                                       let sighash_parts = bip143::SighashComponents::new(&single_htlc_tx);
+                                                                                       let (redeemscript, htlc_key) = sign_input!(sighash_parts, single_htlc_tx.input[0], htlc.amount_msat / 1000, payment_preimage.0.to_vec());
+                                                                                       assert!(predicted_weight >= single_htlc_tx.get_weight());
+                                                                                       spendable_outputs.push(SpendableOutputDescriptor::StaticOutput {
+                                                                                               outpoint: BitcoinOutPoint { txid: single_htlc_tx.txid(), vout: 0 },
+                                                                                               output: single_htlc_tx.output[0].clone(),
+                                                                                       });
+                                                                                       match self.our_claim_txn_waiting_first_conf.entry(single_htlc_tx.input[0].previous_output.clone()) {
+                                                                                               hash_map::Entry::Occupied(_) => {},
+                                                                                               hash_map::Entry::Vacant(entry) => { entry.insert((height_timer, TxMaterial::RemoteHTLC { script: redeemscript, key: htlc_key, preimage: Some(*payment_preimage), amount: htlc.amount_msat / 1000 }, used_feerate, htlc.cltv_expiry, height)); }
+                                                                                       }
+                                                                                       txn_to_broadcast.push(single_htlc_tx);
                                                                                }
-                                                                               txn_to_broadcast.push(single_htlc_tx);
                                                                        }
                                                                }
                                                        }
@@ -1662,6 +1710,7 @@ impl ChannelMonitor {
                                                                        }),
                                                                };
                                                                let predicted_weight = timeout_tx.get_weight() + Self::get_witnesses_weight(&[InputDescriptors::ReceivedHTLC]);
+                                                               let height_timer = Self::get_height_timer(height, htlc.cltv_expiry);
                                                                let mut used_feerate;
                                                                if subtract_high_prio_fee!(self, fee_estimator, timeout_tx.output[0].value, predicted_weight, tx.txid(), used_feerate) {
                                                                        let sighash_parts = bip143::SighashComponents::new(&timeout_tx);
@@ -1670,7 +1719,7 @@ impl ChannelMonitor {
                                                                        //TODO: track SpendableOutputDescriptor
                                                                        match self.our_claim_txn_waiting_first_conf.entry(timeout_tx.input[0].previous_output.clone()) {
                                                                                hash_map::Entry::Occupied(_) => {},
-                                                                               hash_map::Entry::Vacant(entry) => { entry.insert((height + 3, TxMaterial::RemoteHTLC { script : redeemscript, key: htlc_key, preimage: None, amount: htlc.amount_msat / 1000 }, used_feerate)); }
+                                                                               hash_map::Entry::Vacant(entry) => { entry.insert((height_timer, TxMaterial::RemoteHTLC { script : redeemscript, key: htlc_key, preimage: None, amount: htlc.amount_msat / 1000 }, used_feerate, htlc.cltv_expiry, height)); }
                                                                        }
                                                                }
                                                                txn_to_broadcast.push(timeout_tx);
@@ -1702,9 +1751,10 @@ impl ChannelMonitor {
 
                                        for (input, info) in spend_tx.input.iter_mut().zip(inputs_info.iter()) {
                                                let (redeemscript, htlc_key) = sign_input!(sighash_parts, input, info.1, (info.0).0.to_vec());
+                                               let height_timer = Self::get_height_timer(height, info.2);
                                                match self.our_claim_txn_waiting_first_conf.entry(input.previous_output.clone()) {
                                                        hash_map::Entry::Occupied(_) => {},
-                                                       hash_map::Entry::Vacant(entry) => { entry.insert((height + 3, TxMaterial::RemoteHTLC { script: redeemscript, key: htlc_key, preimage: Some(*(info.0)), amount: info.1}, used_feerate)); }
+                                                       hash_map::Entry::Vacant(entry) => { entry.insert((height_timer, TxMaterial::RemoteHTLC { script: redeemscript, key: htlc_key, preimage: Some(*(info.0)), amount: info.1}, used_feerate, info.2, height)); }
                                                }
                                        }
                                        assert!(predicted_weight >= spend_tx.get_weight());
@@ -1715,6 +1765,16 @@ impl ChannelMonitor {
                                        txn_to_broadcast.push(spend_tx);
                                }
                        }
+               } else if let Some((ref to_remote_rescue, ref local_key)) = self.to_remote_rescue {
+                       for (idx, outp) in tx.output.iter().enumerate() {
+                               if to_remote_rescue == &outp.script_pubkey {
+                                       spendable_outputs.push(SpendableOutputDescriptor::DynamicOutputP2WPKH {
+                                               outpoint: BitcoinOutPoint { txid: commitment_txid, vout: idx as u32 },
+                                               key: local_key.clone(),
+                                               output: outp.clone(),
+                                       });
+                               }
+                       }
                }
 
                (txn_to_broadcast, (commitment_txid, watch_outputs), spendable_outputs)
@@ -1750,7 +1810,7 @@ impl ChannelMonitor {
                        None => return (None, None),
                        Some(their_delayed_payment_base_key) => ignore_error!(chan_utils::derive_public_key(&self.secp_ctx, &per_commitment_point, &their_delayed_payment_base_key)),
                };
-               let redeemscript = chan_utils::get_revokeable_redeemscript(&revocation_pubkey, self.their_to_self_delay.unwrap(), &delayed_key);
+               let redeemscript = chan_utils::get_revokeable_redeemscript(&revocation_pubkey, self.our_to_self_delay, &delayed_key);
                let revokeable_p2wsh = redeemscript.to_v0_p2wsh();
                let htlc_txid = tx.txid(); //TODO: This is gonna be a performance bottleneck for watchtowers!
 
@@ -1808,15 +1868,16 @@ impl ChannelMonitor {
                        assert!(predicted_weight >= spend_tx.get_weight());
                        let outpoint = BitcoinOutPoint { txid: spend_tx.txid(), vout: 0 };
                        let output = spend_tx.output[0].clone();
+                       let height_timer = Self::get_height_timer(height, self.their_to_self_delay.unwrap() as u32); // We can safely unwrap given we are past channel opening
                        match self.our_claim_txn_waiting_first_conf.entry(spend_tx.input[0].previous_output.clone()) {
                                hash_map::Entry::Occupied(_) => {},
-                               hash_map::Entry::Vacant(entry) => { entry.insert((height + 3, TxMaterial::Revoked { script: redeemscript, pubkey: None, key: revocation_key, is_htlc: false, amount: tx.output[0].value }, used_feerate)); }
+                               hash_map::Entry::Vacant(entry) => { entry.insert((height_timer, TxMaterial::Revoked { script: redeemscript, pubkey: None, key: revocation_key, is_htlc: false, amount: tx.output[0].value }, used_feerate, height + self.our_to_self_delay as u32, height)); }
                        }
                        (Some(spend_tx), Some(SpendableOutputDescriptor::StaticOutput { outpoint, output }))
                } else { (None, None) }
        }
 
-       fn broadcast_by_local_state(&self, local_tx: &LocalSignedTx, per_commitment_point: &Option<PublicKey>, delayed_payment_base_key: &Option<SecretKey>, height: u32) -> (Vec<Transaction>, Vec<SpendableOutputDescriptor>, Vec<TxOut>, Vec<(BitcoinOutPoint, (u32, TxMaterial, u64))>) {
+       fn broadcast_by_local_state(&self, local_tx: &LocalSignedTx, per_commitment_point: &Option<PublicKey>, delayed_payment_base_key: &Option<SecretKey>, height: u32) -> (Vec<Transaction>, Vec<SpendableOutputDescriptor>, Vec<TxOut>, Vec<(BitcoinOutPoint, (u32, TxMaterial, u64, u32, u32))>) {
                let mut res = Vec::with_capacity(local_tx.htlc_outputs.len());
                let mut spendable_outputs = Vec::with_capacity(local_tx.htlc_outputs.len());
                let mut watch_outputs = Vec::with_capacity(local_tx.htlc_outputs.len());
@@ -1869,7 +1930,8 @@ impl ChannelMonitor {
                                                htlc_timeout_tx.input[0].witness.push(htlc_script.clone().into_bytes());
 
                                                add_dynamic_output!(htlc_timeout_tx, 0);
-                                               pending_claims.push((htlc_timeout_tx.input[0].previous_output.clone(), (height + 3, TxMaterial::LocalHTLC { script: htlc_script, sigs: (*their_sig, *our_sig), preimage: None, amount: htlc.amount_msat / 1000}, 0)));
+                                               let height_timer = Self::get_height_timer(height, htlc.cltv_expiry);
+                                               pending_claims.push((htlc_timeout_tx.input[0].previous_output.clone(), (height_timer, TxMaterial::LocalHTLC { script: htlc_script, sigs: (*their_sig, *our_sig), preimage: None, amount: htlc.amount_msat / 1000}, 0, htlc.cltv_expiry, height)));
                                                res.push(htlc_timeout_tx);
                                        } else {
                                                if let Some(payment_preimage) = self.payment_preimages.get(&htlc.payment_hash) {
@@ -1888,7 +1950,8 @@ impl ChannelMonitor {
                                                        htlc_success_tx.input[0].witness.push(htlc_script.clone().into_bytes());
 
                                                        add_dynamic_output!(htlc_success_tx, 0);
-                                                       pending_claims.push((htlc_success_tx.input[0].previous_output.clone(), (height + 3, TxMaterial::LocalHTLC { script: htlc_script, sigs: (*their_sig, *our_sig), preimage: Some(*payment_preimage), amount: htlc.amount_msat / 1000}, 0)));
+                                                       let height_timer = Self::get_height_timer(height, htlc.cltv_expiry);
+                                                       pending_claims.push((htlc_success_tx.input[0].previous_output.clone(), (height_timer, TxMaterial::LocalHTLC { script: htlc_script, sigs: (*their_sig, *our_sig), preimage: Some(*payment_preimage), amount: htlc.amount_msat / 1000}, 0, htlc.cltv_expiry, height)));
                                                        res.push(htlc_success_tx);
                                                }
                                        }
@@ -2027,9 +2090,16 @@ impl ChannelMonitor {
                None
        }
 
-       /// Used by ChannelManager deserialization to broadcast the latest local state if it's copy of
-       /// the Channel was out-of-date.
-       pub(super) fn get_latest_local_commitment_txn(&self) -> Vec<Transaction> {
+       /// Used by ChannelManager deserialization to broadcast the latest local state if its copy of
+       /// the Channel was out-of-date. You may use it to get a broadcastable local toxic tx in case of
+       /// fallen-behind, i.e when receiving a channel_reestablish with a proof that our remote side knows
+       /// a higher revocation secret than the local commitment number we are aware of. Broadcasting these
+       /// transactions are UNSAFE, as they allow remote side to punish you. Nevertheless you may want to
+       /// broadcast them if remote don't close channel with his higher commitment transaction after a
+       /// substantial amount of time (a month or even a year) to get back funds. Best may be to contact
+       /// out-of-band the other node operator to coordinate with him if option is available to you.
+       /// In any-case, choice is up to the user.
+       pub fn get_latest_local_commitment_txn(&self) -> Vec<Transaction> {
                if let &Some(ref local_tx) = &self.current_local_signed_commitment_tx {
                        let mut res = vec![local_tx.tx.clone()];
                        match self.key_storage {
@@ -2067,19 +2137,21 @@ impl ChannelMonitor {
                                        }
                                };
                                if funding_txo.is_none() || (prevout.txid == funding_txo.as_ref().unwrap().0.txid && prevout.vout == funding_txo.as_ref().unwrap().0.index as u32) {
-                                       let (remote_txn, new_outputs, mut spendable_output) = self.check_spend_remote_transaction(tx, height, fee_estimator);
-                                       txn = remote_txn;
-                                       spendable_outputs.append(&mut spendable_output);
-                                       if !new_outputs.1.is_empty() {
-                                               watch_outputs.push(new_outputs);
-                                       }
-                                       if txn.is_empty() {
-                                               let (local_txn, mut spendable_output, new_outputs) = self.check_spend_local_transaction(tx, height);
+                                       if (tx.input[0].sequence >> 8*3) as u8 == 0x80 && (tx.lock_time >> 8*3) as u8 == 0x20 {
+                                               let (remote_txn, new_outputs, mut spendable_output) = self.check_spend_remote_transaction(tx, height, fee_estimator);
+                                               txn = remote_txn;
                                                spendable_outputs.append(&mut spendable_output);
-                                               txn = local_txn;
                                                if !new_outputs.1.is_empty() {
                                                        watch_outputs.push(new_outputs);
                                                }
+                                               if txn.is_empty() {
+                                                       let (local_txn, mut spendable_output, new_outputs) = self.check_spend_local_transaction(tx, height);
+                                                       spendable_outputs.append(&mut spendable_output);
+                                                       txn = local_txn;
+                                                       if !new_outputs.1.is_empty() {
+                                                               watch_outputs.push(new_outputs);
+                                                       }
+                                               }
                                        }
                                        if !funding_txo.is_none() && txn.is_empty() {
                                                if let Some(spendable_output) = self.check_spend_closing_transaction(tx) {
@@ -2190,7 +2262,7 @@ impl ChannelMonitor {
                        //- htlc update there as failure-trigger tx (revoked commitment tx, non-revoked commitment tx, HTLC-timeout tx) has been disconnected
                        //- our claim tx on a commitment tx output
                }
-               self.our_claim_txn_waiting_first_conf.retain(|_, ref mut v| if v.0 == height + 3 { false } else { true });
+               self.our_claim_txn_waiting_first_conf.retain(|_, ref mut v| if v.3 == height { false } else { true });
                self.last_block_hash = block_hash.clone();
        }
 
@@ -2606,6 +2678,15 @@ impl<R: ::std::io::Read> ReadableArgs<R, Arc<Logger>> for (Sha256dHash, ChannelM
 
                let last_block_hash: Sha256dHash = Readable::read(reader)?;
                let destination_script = Readable::read(reader)?;
+               let to_remote_rescue = match <u8 as Readable<R>>::read(reader)? {
+                       0 => None,
+                       1 => {
+                               let to_remote_script = Readable::read(reader)?;
+                               let local_key = Readable::read(reader)?;
+                               Some((to_remote_script, local_key))
+                       }
+                       _ => return Err(DecodeError::InvalidValue),
+               };
 
                let our_claim_txn_waiting_first_conf_len: u64 = Readable::read(reader)?;
                let mut our_claim_txn_waiting_first_conf = HashMap::with_capacity(cmp::min(our_claim_txn_waiting_first_conf_len as usize, MAX_ALLOC_SIZE / 128));
@@ -2659,7 +2740,9 @@ impl<R: ::std::io::Read> ReadableArgs<R, Arc<Logger>> for (Sha256dHash, ChannelM
                                _ => return Err(DecodeError::InvalidValue),
                        };
                        let last_fee = Readable::read(reader)?;
-                       our_claim_txn_waiting_first_conf.insert(outpoint, (height_target, tx_material, last_fee));
+                       let timelock_expiration = Readable::read(reader)?;
+                       let height = Readable::read(reader)?;
+                       our_claim_txn_waiting_first_conf.insert(outpoint, (height_target, tx_material, last_fee, timelock_expiration, height));
                }
 
                let waiting_threshold_conf_len: u64 = Readable::read(reader)?;
@@ -2713,6 +2796,7 @@ impl<R: ::std::io::Read> ReadableArgs<R, Arc<Logger>> for (Sha256dHash, ChannelM
                        payment_preimages,
 
                        destination_script,
+                       to_remote_rescue,
 
                        our_claim_txn_waiting_first_conf,
 
@@ -3225,7 +3309,7 @@ mod tests {
                let secp_ctx = Secp256k1::new();
                let privkey = SecretKey::from_slice(&hex::decode("0101010101010101010101010101010101010101010101010101010101010101").unwrap()[..]).unwrap();
                let pubkey = PublicKey::from_secret_key(&secp_ctx, &privkey);
-               let mut sum_actual_sigs: u64 = 0;
+               let mut sum_actual_sigs = 0;
 
                macro_rules! sign_input {
                        ($sighash_parts: expr, $input: expr, $idx: expr, $amount: expr, $input_type: expr, $sum_actual_sigs: expr) => {
@@ -3241,7 +3325,7 @@ mod tests {
                                let sig = secp_ctx.sign(&sighash, &privkey);
                                $input.witness.push(sig.serialize_der().to_vec());
                                $input.witness[0].push(SigHashType::All as u8);
-                               sum_actual_sigs += $input.witness[0].len() as u64;
+                               sum_actual_sigs += $input.witness[0].len();
                                if *$input_type == InputDescriptors::RevokedOutput {
                                        $input.witness.push(vec!(1));
                                } else if *$input_type == InputDescriptors::RevokedOfferedHTLC || *$input_type == InputDescriptors::RevokedReceivedHTLC {
@@ -3284,7 +3368,7 @@ 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 + ChannelMonitor::get_witnesses_weight(&inputs_des[..]),  claim_tx.get_weight() + /* max_length_sig */ (73 * inputs_des.len() as u64 - sum_actual_sigs));
+               assert_eq!(base_weight + ChannelMonitor::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();
@@ -3306,7 +3390,7 @@ 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 + ChannelMonitor::get_witnesses_weight(&inputs_des[..]),  claim_tx.get_weight() + /* max_length_sig */ (73 * inputs_des.len() as u64 - sum_actual_sigs));
+               assert_eq!(base_weight + ChannelMonitor::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();
@@ -3326,7 +3410,7 @@ 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 + ChannelMonitor::get_witnesses_weight(&inputs_des[..]), claim_tx.get_weight() + /* max_length_isg */ (73 * inputs_des.len() as u64 - sum_actual_sigs));
+               assert_eq!(base_weight + ChannelMonitor::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.