WIP

[rust-lightning] / lightning / src / ln / onchaintx.rs

//! The logic to build claims and bump in-flight transactions until confirmations.
//!
//! OnchainTxHandler objetcs are fully-part of ChannelMonitor and encapsulates all
//! building, tracking, bumping and notifications functions.

use bitcoin::blockdata::transaction::{Transaction, TxIn, TxOut, SigHashType};
use bitcoin::blockdata::transaction::OutPoint as BitcoinOutPoint;
use bitcoin::blockdata::script::Script;
use bitcoin::util::bip143;

use bitcoin::hash_types::Txid;

use bitcoin::secp256k1::{Secp256k1, Signature};
use bitcoin::secp256k1;

use ln::msgs::DecodeError;
use ln::channelmonitor::{ANTI_REORG_DELAY, CLTV_SHARED_CLAIM_BUFFER, InputMaterial, ClaimRequest};
use ln::channelmanager::PaymentPreimage;
use ln::chan_utils::{HTLCType, LocalCommitmentTransaction};
use chain::chaininterface::{FeeEstimator, BroadcasterInterface, ConfirmationTarget, MIN_RELAY_FEE_SAT_PER_1000_WEIGHT};
use chain::keysinterface::ChannelKeys;
use util::logger::Logger;
use util::ser::{Readable, Writer, Writeable};
use util::byte_utils;

use std::collections::{HashMap, hash_map};
use std::cmp;
use std::ops::Deref;

const MAX_ALLOC_SIZE: usize = 64*1024;

/// Upon discovering of some classes of onchain tx by ChannelMonitor, we may have to take actions on it
/// once they mature to enough confirmations (ANTI_REORG_DELAY)
#[derive(Clone, PartialEq)]
enum OnchainEvent {
        /// Outpoint under claim process by our own tx, once this one get enough confirmations, we remove it from
        /// bump-txn candidate buffer.
        Claim {
                claim_request: Txid,
        },
        /// Claim tx aggregate multiple claimable outpoints. One of the outpoint may be claimed by a remote party tx.
        /// In this case, we need to drop the outpoint and regenerate a new claim tx. By safety, we keep tracking
        /// the outpoint to be sure to resurect it back to the claim tx if reorgs happen.
        ContentiousOutpoint {
                outpoint: BitcoinOutPoint,
                input_material: InputMaterial,
        }
}

/// Higher-level cache structure needed to re-generate bumped claim txn if needed
#[derive(Clone, PartialEq)]
pub struct ClaimTxBumpMaterial {
        // At every block tick, used to check if pending claiming tx is taking too
        // much time for confirmation and we need to bump it.
        height_timer: Option<u32>,
        // Tracked in case of reorg to wipe out now-superflous bump material
        feerate_previous: u64,
        // Soonest timelocks among set of outpoints claimed, used to compute
        // a priority of not feerate
        soonest_timelock: u32,
        // Cache of script, pubkey, sig or key to solve claimable outputs scriptpubkey.
        per_input_material: HashMap<BitcoinOutPoint, InputMaterial>,
}

impl Writeable for ClaimTxBumpMaterial  {
        fn write<W: Writer>(&self, writer: &mut W) -> Result<(), ::std::io::Error> {
                self.height_timer.write(writer)?;
                writer.write_all(&byte_utils::be64_to_array(self.feerate_previous))?;
                writer.write_all(&byte_utils::be32_to_array(self.soonest_timelock))?;
                writer.write_all(&byte_utils::be64_to_array(self.per_input_material.len() as u64))?;
                for (outp, tx_material) in self.per_input_material.iter() {
                        outp.write(writer)?;
                        tx_material.write(writer)?;
                }
                Ok(())
        }
}

impl Readable for ClaimTxBumpMaterial {
        fn read<R: ::std::io::Read>(reader: &mut R) -> Result<Self, DecodeError> {
                let height_timer = Readable::read(reader)?;
                let feerate_previous = Readable::read(reader)?;
                let soonest_timelock = Readable::read(reader)?;
                let per_input_material_len: u64 = Readable::read(reader)?;
                let mut per_input_material = HashMap::with_capacity(cmp::min(per_input_material_len as usize, MAX_ALLOC_SIZE / 128));
                for _ in 0 ..per_input_material_len {
                        let outpoint = Readable::read(reader)?;
                        let input_material = Readable::read(reader)?;
                        per_input_material.insert(outpoint, input_material);
                }
                Ok(Self { height_timer, feerate_previous, soonest_timelock, per_input_material })
        }
}

#[derive(PartialEq)]
pub(super) 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
}

macro_rules! subtract_high_prio_fee {
        ($logger: ident, $fee_estimator: expr, $value: expr, $predicted_weight: expr, $used_feerate: expr) => {
                {
                        $used_feerate = $fee_estimator.get_est_sat_per_1000_weight(ConfirmationTarget::HighPriority);
                        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 as u64) / 1000;
                                if $value <= fee {
                                        $used_feerate = $fee_estimator.get_est_sat_per_1000_weight(ConfirmationTarget::Background);
                                        fee = $used_feerate * ($predicted_weight as u64) / 1000;
                                        if $value <= fee {
                                                log_error!($logger, "Failed to generate an on-chain punishment tx as even low priority fee ({} sat) was more than the entire claim balance ({} sat)",
                                                        fee, $value);
                                                false
                                        } else {
                                                log_warn!($logger, "Used low priority fee for on-chain punishment tx as high priority fee was more than the entire claim balance ({} sat)",
                                                        $value);
                                                $value -= fee;
                                                true
                                        }
                                } else {
                                        log_warn!($logger, "Used medium priority fee for on-chain punishment tx as high priority fee was more than the entire claim balance ({} sat)",
                                                $value);
                                        $value -= fee;
                                        true
                                }
                        } else {
                                $value -= fee;
                                true
                        }
                }
        }
}

impl Readable for Option<Vec<Option<(usize, Signature)>>> {
        fn read<R: ::std::io::Read>(reader: &mut R) -> Result<Self, DecodeError> {
                match Readable::read(reader)? {
                        0u8 => Ok(None),
                        1u8 => {
                                let vlen: u64 = Readable::read(reader)?;
                                let mut ret = Vec::with_capacity(cmp::min(vlen as usize, MAX_ALLOC_SIZE / ::std::mem::size_of::<Option<(usize, Signature)>>()));
                                for _ in 0..vlen {
                                        ret.push(match Readable::read(reader)? {
                                                0u8 => None,
                                                1u8 => Some((<u64 as Readable>::read(reader)? as usize, Readable::read(reader)?)),
                                                _ => return Err(DecodeError::InvalidValue)
                                        });
                                }
                                Ok(Some(ret))
                        },
                        _ => Err(DecodeError::InvalidValue),
                }
        }
}

impl Writeable for Option<Vec<Option<(usize, Signature)>>> {
        fn write<W: Writer>(&self, writer: &mut W) -> Result<(), ::std::io::Error> {
                match self {
                        &Some(ref vec) => {
                                1u8.write(writer)?;
                                (vec.len() as u64).write(writer)?;
                                for opt in vec.iter() {
                                        match opt {
                                                &Some((ref idx, ref sig)) => {
                                                        1u8.write(writer)?;
                                                        (*idx as u64).write(writer)?;
                                                        sig.write(writer)?;
                                                },
                                                &None => 0u8.write(writer)?,
                                        }
                                }
                        },
                        &None => 0u8.write(writer)?,
                }
                Ok(())
        }
}


/// OnchainTxHandler receives claiming requests, aggregates them if it's sound, broadcast and
/// do RBF bumping if possible.
pub struct OnchainTxHandler<ChanSigner: ChannelKeys> {
        destination_script: Script,
        local_commitment: Option<LocalCommitmentTransaction>,
        // local_htlc_sigs and prev_local_htlc_sigs are in the order as they appear in the commitment
        // transaction outputs (hence the Option<>s inside the Vec). The first usize is the index in
        // the set of HTLCs in the LocalCommitmentTransaction (including those which do not appear in
        // the commitment transaction).
        local_htlc_sigs: Option<Vec<Option<(usize, Signature)>>>,
        prev_local_commitment: Option<LocalCommitmentTransaction>,
        prev_local_htlc_sigs: Option<Vec<Option<(usize, Signature)>>>,
        local_csv: u16,

        key_storage: ChanSigner,

        // Used to track claiming requests. If claim tx doesn't confirm before height timer expiration we need to bump
        // it (RBF or CPFP). If an input has been part of an aggregate tx at first claim try, we need to keep it within
        // another bumped aggregate tx to comply with RBF rules. We may have multiple claiming txn in the flight for the
        // same set of outpoints. One of the outpoints may be spent by a transaction not issued by us. That's why at
        // block connection we scan all inputs and if any of them is among a set of a claiming request we test for set
        // equality between spending transaction and claim request. If true, it means transaction was one our claiming one
        // after a security delay of 6 blocks we remove pending claim request. If false, it means transaction wasn't and
        // we need to regenerate new claim request with reduced set of still-claimable outpoints.
        // Key is identifier of the pending claim request, i.e the txid of the initial claiming transaction generated by
        // us and is immutable until all outpoint of the claimable set are post-anti-reorg-delay solved.
        // Entry is cache of elements need to generate a bumped claiming transaction (see ClaimTxBumpMaterial)
        #[cfg(test)] // Used in functional_test to verify sanitization
        pub pending_claim_requests: HashMap<Txid, ClaimTxBumpMaterial>,
        #[cfg(not(test))]
        pending_claim_requests: HashMap<Txid, ClaimTxBumpMaterial>,

        // Used to link outpoints claimed in a connected block to a pending claim request.
        // Key is outpoint than monitor parsing has detected we have keys/scripts to claim
        // Value is (pending claim request identifier, confirmation_block), identifier
        // is txid of the initial claiming transaction and is immutable until outpoint is
        // post-anti-reorg-delay solved, confirmaiton_block is used to erase entry if
        // block with output gets disconnected.
        #[cfg(test)] // Used in functional_test to verify sanitization
        pub claimable_outpoints: HashMap<BitcoinOutPoint, (Txid, u32)>,
        #[cfg(not(test))]
        claimable_outpoints: HashMap<BitcoinOutPoint, (Txid, u32)>,

        onchain_events_waiting_threshold_conf: HashMap<u32, Vec<OnchainEvent>>,

        secp_ctx: Secp256k1<secp256k1::All>,
}

impl<ChanSigner: ChannelKeys + Writeable> OnchainTxHandler<ChanSigner> {
        pub(crate) fn write<W: Writer>(&self, writer: &mut W) -> Result<(), ::std::io::Error> {
                self.destination_script.write(writer)?;
                self.local_commitment.write(writer)?;
                self.local_htlc_sigs.write(writer)?;
                self.prev_local_commitment.write(writer)?;
                self.prev_local_htlc_sigs.write(writer)?;

                self.local_csv.write(writer)?;

                self.key_storage.write(writer)?;

                writer.write_all(&byte_utils::be64_to_array(self.pending_claim_requests.len() as u64))?;
                for (ref ancestor_claim_txid, claim_tx_data) in self.pending_claim_requests.iter() {
                        ancestor_claim_txid.write(writer)?;
                        claim_tx_data.write(writer)?;
                }

                writer.write_all(&byte_utils::be64_to_array(self.claimable_outpoints.len() as u64))?;
                for (ref outp, ref claim_and_height) in self.claimable_outpoints.iter() {
                        outp.write(writer)?;
                        claim_and_height.0.write(writer)?;
                        claim_and_height.1.write(writer)?;
                }

                writer.write_all(&byte_utils::be64_to_array(self.onchain_events_waiting_threshold_conf.len() as u64))?;
                for (ref target, ref events) in self.onchain_events_waiting_threshold_conf.iter() {
                        writer.write_all(&byte_utils::be32_to_array(**target))?;
                        writer.write_all(&byte_utils::be64_to_array(events.len() as u64))?;
                        for ev in events.iter() {
                                match *ev {
                                        OnchainEvent::Claim { ref claim_request } => {
                                                writer.write_all(&[0; 1])?;
                                                claim_request.write(writer)?;
                                        },
                                        OnchainEvent::ContentiousOutpoint { ref outpoint, ref input_material } => {
                                                writer.write_all(&[1; 1])?;
                                                outpoint.write(writer)?;
                                                input_material.write(writer)?;
                                        }
                                }
                        }
                }
                Ok(())
        }
}

impl<ChanSigner: ChannelKeys + Readable> Readable for OnchainTxHandler<ChanSigner> {
        fn read<R: ::std::io::Read>(reader: &mut R) -> Result<Self, DecodeError> {
                let destination_script = Readable::read(reader)?;

                let local_commitment = Readable::read(reader)?;
                let local_htlc_sigs = Readable::read(reader)?;
                let prev_local_commitment = Readable::read(reader)?;
                let prev_local_htlc_sigs = Readable::read(reader)?;

                let local_csv = Readable::read(reader)?;

                let key_storage = Readable::read(reader)?;

                let pending_claim_requests_len: u64 = Readable::read(reader)?;
                let mut pending_claim_requests = HashMap::with_capacity(cmp::min(pending_claim_requests_len as usize, MAX_ALLOC_SIZE / 128));
                for _ in 0..pending_claim_requests_len {
                        pending_claim_requests.insert(Readable::read(reader)?, Readable::read(reader)?);
                }

                let claimable_outpoints_len: u64 = Readable::read(reader)?;
                let mut claimable_outpoints = HashMap::with_capacity(cmp::min(pending_claim_requests_len as usize, MAX_ALLOC_SIZE / 128));
                for _ in 0..claimable_outpoints_len {
                        let outpoint = Readable::read(reader)?;
                        let ancestor_claim_txid = Readable::read(reader)?;
                        let height = Readable::read(reader)?;
                        claimable_outpoints.insert(outpoint, (ancestor_claim_txid, height));
                }
                let waiting_threshold_conf_len: u64 = Readable::read(reader)?;
                let mut onchain_events_waiting_threshold_conf = HashMap::with_capacity(cmp::min(waiting_threshold_conf_len as usize, MAX_ALLOC_SIZE / 128));
                for _ in 0..waiting_threshold_conf_len {
                        let height_target = Readable::read(reader)?;
                        let events_len: u64 = Readable::read(reader)?;
                        let mut events = Vec::with_capacity(cmp::min(events_len as usize, MAX_ALLOC_SIZE / 128));
                        for _ in 0..events_len {
                                let ev = match <u8 as Readable>::read(reader)? {
                                        0 => {
                                                let claim_request = Readable::read(reader)?;
                                                OnchainEvent::Claim {
                                                        claim_request
                                                }
                                        },
                                        1 => {
                                                let outpoint = Readable::read(reader)?;
                                                let input_material = Readable::read(reader)?;
                                                OnchainEvent::ContentiousOutpoint {
                                                        outpoint,
                                                        input_material
                                                }
                                        }
                                        _ => return Err(DecodeError::InvalidValue),
                                };
                                events.push(ev);
                        }
                        onchain_events_waiting_threshold_conf.insert(height_target, events);
                }

                Ok(OnchainTxHandler {
                        destination_script,
                        local_commitment,
                        local_htlc_sigs,
                        prev_local_commitment,
                        prev_local_htlc_sigs,
                        local_csv,
                        key_storage,
                        claimable_outpoints,
                        pending_claim_requests,
                        onchain_events_waiting_threshold_conf,
                        secp_ctx: Secp256k1::new(),
                })
        }
}

impl<ChanSigner: ChannelKeys> OnchainTxHandler<ChanSigner> {
        pub(super) fn new(destination_script: Script, keys: ChanSigner, local_csv: u16) -> Self {

                let key_storage = keys;

                OnchainTxHandler {
                        destination_script,
                        local_commitment: None,
                        local_htlc_sigs: None,
                        prev_local_commitment: None,
                        prev_local_htlc_sigs: None,
                        local_csv,
                        key_storage,
                        pending_claim_requests: HashMap::new(),
                        claimable_outpoints: HashMap::new(),
                        onchain_events_waiting_threshold_conf: HashMap::new(),

                        secp_ctx: Secp256k1::new(),
                }
        }

        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 + 136
                                },
                                // number_of_witness_elements + sig_length + revocation_sig + pubkey_length + revocationpubkey + witness_script_length + witness_script
                                &InputDescriptors::RevokedReceivedHTLC => {
                                        1 + 1 + 73 + 1 + 33 + 1 + 142
                                },
                                // number_of_witness_elements + sig_length + remotehtlc_sig  + preimage_length + preimage + witness_script_length + witness_script
                                &InputDescriptors::OfferedHTLC => {
                                        1 + 1 + 73 + 1 + 32 + 1 + 136
                                },
                                // number_of_witness_elements + sig_length + revocation_sig + pubkey_length + revocationpubkey + witness_script_length + witness_script
                                &InputDescriptors::ReceivedHTLC => {
                                        1 + 1 + 73 + 1 + 1 + 1 + 142
                                },
                                // 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
        /// than our counterparty can do it too. If timelock expires soon, height timer is going to be scale down in consequence to increase
        /// frequency of the bump and so increase our bets of success.
        fn get_height_timer(current_height: u32, timelock_expiration: u32) -> u32 {
                if timelock_expiration <= current_height + 3 {
                        return current_height + 1
                } else if timelock_expiration - current_height <= 15 {
                        return current_height + 3
                }
                current_height + 15
        }

        /// Lightning security model (i.e being able to redeem/timeout HTLC or penalize coutnerparty onchain) lays on the assumption of claim transactions getting confirmed before timelock expiration
        /// (CSV or CLTV following cases). In case of high-fee spikes, claim tx may stuck in the mempool, so you need to bump its feerate quickly using Replace-By-Fee or Child-Pay-For-Parent.
        fn generate_claim_tx<F: Deref, L: Deref>(&mut self, height: u32, cached_claim_datas: &ClaimTxBumpMaterial, fee_estimator: F, logger: L) -> Option<(Option<u32>, u64, Transaction)>
                where F::Target: FeeEstimator,
                                        L::Target: Logger,
        {
                if cached_claim_datas.per_input_material.len() == 0 { return None } // But don't prune pending claiming request yet, we may have to resurrect HTLCs
                let mut inputs = Vec::new();
                for (outp, material) in cached_claim_datas.per_input_material.iter() {
                        log_trace!(logger, "Outpoint {}:{}", outp.txid, outp.vout);
                        inputs.push(TxIn {
                                previous_output: *outp,
                                script_sig: Script::new(),
                                sequence: match material {
                                        &InputMaterial::Revoked { .. } => 1, // XXX: Depends on spec discussion
                                        &InputMaterial::RemoteHTLC { .. } => 1,
                                        &InputMaterial::LocalHTLC { .. } => 1,
                                },
                                witness: Vec::new(),
                        });
                }
                let mut bumped_tx = Transaction {
                        version: 2,
                        lock_time: 0,
                        input: inputs,
                        output: vec![TxOut {
                                script_pubkey: self.destination_script.clone(),
                                value: 0
                        }],
                };

                macro_rules! RBF_bump {
                        ($amount: expr, $old_feerate: expr, $fee_estimator: expr, $predicted_weight: expr) => {
                                {
                                        let mut used_feerate;
                                        // If old feerate inferior to actual one given back by Fee Estimator, use it to compute new fee...
                                        let new_fee = if $old_feerate < $fee_estimator.get_est_sat_per_1000_weight(ConfirmationTarget::HighPriority) {
                                                let mut value = $amount;
                                                if subtract_high_prio_fee!(logger, $fee_estimator, value, $predicted_weight, used_feerate) {
                                                        // Overflow check is done in subtract_high_prio_fee
                                                        $amount - value
                                                } else {
                                                        log_trace!(logger, "Can't new-estimation bump new claiming tx, amount {} is too small", $amount);
                                                        return None;
                                                }
                                        // ...else just increase the previous feerate by 25% (because that's a nice number)
                                        } else {
                                                let fee = $old_feerate * $predicted_weight / 750;
                                                if $amount <= fee {
                                                        log_trace!(logger, "Can't 25% bump new claiming tx, amount {} is too small", $amount);
                                                        return None;
                                                }
                                                fee
                                        };

                                        let previous_fee = $old_feerate * $predicted_weight / 1000;
                                        let min_relay_fee = MIN_RELAY_FEE_SAT_PER_1000_WEIGHT * $predicted_weight / 1000;
                                        // BIP 125 Opt-in Full Replace-by-Fee Signaling
                                        //      * 3. The replacement transaction pays an absolute fee of at least the sum paid by the original transactions.
                                        //      * 4. The replacement transaction must also pay for its own bandwidth at or above the rate set by the node's minimum relay fee setting.
                                        let new_fee = if new_fee < previous_fee + min_relay_fee {
                                                new_fee + previous_fee + min_relay_fee - new_fee
                                        } else {
                                                new_fee
                                        };
                                        Some((new_fee, new_fee * 1000 / $predicted_weight))
                                }
                        }
                }

                // Compute new height timer to decide when we need to regenerate a new bumped version of the claim tx (if we
                // didn't receive confirmation of it before, or not enough reorg-safe depth on top of it).
                let new_timer = Some(Self::get_height_timer(height, cached_claim_datas.soonest_timelock));
                let mut inputs_witnesses_weight = 0;
                let mut amt = 0;
                let mut dynamic_fee = true;
                for per_outp_material in cached_claim_datas.per_input_material.values() {
                        match per_outp_material {
                                &InputMaterial::Revoked { ref witness_script, ref is_htlc, ref amount, .. } => {
                                        inputs_witnesses_weight += Self::get_witnesses_weight(if !is_htlc { &[InputDescriptors::RevokedOutput] } else if HTLCType::scriptlen_to_htlctype(witness_script.len()) == Some(HTLCType::OfferedHTLC) { &[InputDescriptors::RevokedOfferedHTLC] } else if HTLCType::scriptlen_to_htlctype(witness_script.len()) == Some(HTLCType::AcceptedHTLC) { &[InputDescriptors::RevokedReceivedHTLC] } else { unreachable!() });
                                        amt += *amount;
                                },
                                &InputMaterial::RemoteHTLC { ref preimage, ref amount, .. } => {
                                        inputs_witnesses_weight += Self::get_witnesses_weight(if preimage.is_some() { &[InputDescriptors::OfferedHTLC] } else { &[InputDescriptors::ReceivedHTLC] });
                                        amt += *amount;
                                },
                                &InputMaterial::LocalHTLC { .. } => {
                                        dynamic_fee = false;
                                },
                                &InputMaterial::Funding { .. } => {
                                        dynamic_fee = false;
                                }
                        }
                }
                if dynamic_fee {
                        let predicted_weight = bumped_tx.get_weight() + inputs_witnesses_weight;
                        let mut new_feerate;
                        // If old feerate is 0, first iteration of this claim, use normal fee calculation
                        if cached_claim_datas.feerate_previous != 0 {
                                if let Some((new_fee, feerate)) = RBF_bump!(amt, cached_claim_datas.feerate_previous, fee_estimator, predicted_weight as u64) {
                                        // If new computed fee is superior at the whole claimable amount burn all in fees
                                        if new_fee > amt {
                                                bumped_tx.output[0].value = 0;
                                        } else {
                                                bumped_tx.output[0].value = amt - new_fee;
                                        }
                                        new_feerate = feerate;
                                } else { return None; }
                        } else {
                                if subtract_high_prio_fee!(logger, fee_estimator, amt, predicted_weight, new_feerate) {
                                        bumped_tx.output[0].value = amt;
                                } else { return None; }
                        }
                        assert!(new_feerate != 0);

                        for (i, (outp, per_outp_material)) in cached_claim_datas.per_input_material.iter().enumerate() {
                                match per_outp_material {
                                        &InputMaterial::Revoked { ref witness_script, ref pubkey, ref key, ref is_htlc, ref amount } => {
                                                let sighash_parts = bip143::SighashComponents::new(&bumped_tx);
                                                let sighash = hash_to_message!(&sighash_parts.sighash_all(&bumped_tx.input[i], &witness_script, *amount)[..]);
                                                let sig = self.secp_ctx.sign(&sighash, &key);
                                                bumped_tx.input[i].witness.push(sig.serialize_der().to_vec());
                                                bumped_tx.input[i].witness[0].push(SigHashType::All as u8);
                                                if *is_htlc {
                                                        bumped_tx.input[i].witness.push(pubkey.unwrap().clone().serialize().to_vec());
                                                } else {
                                                        bumped_tx.input[i].witness.push(vec!(1));
                                                }
                                                bumped_tx.input[i].witness.push(witness_script.clone().into_bytes());
                                                log_trace!(logger, "Going to broadcast Penalty Transaction {} claiming revoked {} output {} from {} with new feerate {}...", bumped_tx.txid(), if !is_htlc { "to_local" } else if HTLCType::scriptlen_to_htlctype(witness_script.len()) == Some(HTLCType::OfferedHTLC) { "offered" } else if HTLCType::scriptlen_to_htlctype(witness_script.len()) == Some(HTLCType::AcceptedHTLC) { "received" } else { "" }, outp.vout, outp.txid, new_feerate);
                                        },
                                        &InputMaterial::RemoteHTLC { ref witness_script, ref key, ref preimage, ref amount, ref locktime } => {
                                                if !preimage.is_some() { bumped_tx.lock_time = *locktime }; // Right now we don't aggregate time-locked transaction, if we do we should set lock_time before to avoid breaking hash computation
                                                let sighash_parts = bip143::SighashComponents::new(&bumped_tx);
                                                let sighash = hash_to_message!(&sighash_parts.sighash_all(&bumped_tx.input[i], &witness_script, *amount)[..]);
                                                let sig = self.secp_ctx.sign(&sighash, &key);
                                                bumped_tx.input[i].witness.push(sig.serialize_der().to_vec());
                                                bumped_tx.input[i].witness[0].push(SigHashType::All as u8);
                                                if let &Some(preimage) = preimage {
                                                        bumped_tx.input[i].witness.push(preimage.clone().0.to_vec());
                                                } else {
                                                        bumped_tx.input[i].witness.push(vec![]);
                                                }
                                                bumped_tx.input[i].witness.push(witness_script.clone().into_bytes());
                                                log_trace!(logger, "Going to broadcast Claim Transaction {} claiming remote {} htlc output {} from {} with new feerate {}...", bumped_tx.txid(), if preimage.is_some() { "offered" } else { "received" }, outp.vout, outp.txid, new_feerate);
                                        },
                                        _ => unreachable!()
                                }
                        }
                        log_trace!(logger, "...with timer {}", new_timer.unwrap());
                        assert!(predicted_weight >= bumped_tx.get_weight());
                        return Some((new_timer, new_feerate, bumped_tx))
                } else {
                        for (_, (outp, per_outp_material)) in cached_claim_datas.per_input_material.iter().enumerate() {
                                match per_outp_material {
                                        &InputMaterial::LocalHTLC { ref preimage, ref amount } => {
                                                let htlc_tx = self.get_fully_signed_htlc_tx(outp, preimage);
                                                if let Some(htlc_tx) = htlc_tx {
                                                        let feerate = (amount - htlc_tx.output[0].value) * 1000 / htlc_tx.get_weight() as u64;
                                                        // Timer set to $NEVER given we can't bump tx without anchor outputs
                                                        log_trace!(logger, "Going to broadcast Local HTLC-{} claiming HTLC output {} from {}...", if preimage.is_some() { "Success" } else { "Timeout" }, outp.vout, outp.txid);
                                                        return Some((None, feerate, htlc_tx));
                                                }
                                                return None;
                                        },
                                        &InputMaterial::Funding { ref funding_redeemscript } => {
                                                let signed_tx = self.get_fully_signed_local_tx(funding_redeemscript).unwrap();
                                                // Timer set to $NEVER given we can't bump tx without anchor outputs
                                                log_trace!(logger, "Going to broadcast Local Transaction {} claiming funding output {} from {}...", signed_tx.txid(), outp.vout, outp.txid);
                                                return Some((None, self.local_commitment.as_ref().unwrap().feerate_per_kw, signed_tx));
                                        }
                                        _ => unreachable!()
                                }
                        }
                }
                None
        }

        pub(super) fn block_connected<B: Deref, F: Deref, L: Deref>(&mut self, txn_matched: &[&Transaction], claimable_outpoints: Vec<ClaimRequest>, height: u32, broadcaster: B, fee_estimator: F, logger: L)
                where B::Target: BroadcasterInterface,
                      F::Target: FeeEstimator,
                                        L::Target: Logger,
        {
                log_trace!(logger, "Block at height {} connected with {} claim requests", height, claimable_outpoints.len());
                let mut new_claims = Vec::new();
                let mut aggregated_claim = HashMap::new();
                let mut aggregated_soonest = ::std::u32::MAX;

                // Try to aggregate outputs if their timelock expiration isn't imminent (absolute_timelock
                // <= CLTV_SHARED_CLAIM_BUFFER) and they don't require an immediate nLockTime (aggregable).
                for req in claimable_outpoints {
                        // Don't claim a outpoint twice that would be bad for privacy and may uselessly lock a CPFP input for a while
                        if let Some(_) = self.claimable_outpoints.get(&req.outpoint) { log_trace!(logger, "Bouncing off outpoint {}:{}, already registered its claiming request", req.outpoint.txid, req.outpoint.vout); } else {
                                log_trace!(logger, "Test if outpoint can be aggregated with expiration {} against {}", req.absolute_timelock, height + CLTV_SHARED_CLAIM_BUFFER);
                                if req.absolute_timelock <= height + CLTV_SHARED_CLAIM_BUFFER || !req.aggregable { // Don't aggregate if outpoint absolute timelock is soon or marked as non-aggregable
                                        let mut single_input = HashMap::new();
                                        single_input.insert(req.outpoint, req.witness_data);
                                        new_claims.push((req.absolute_timelock, single_input));
                                } else {
                                        aggregated_claim.insert(req.outpoint, req.witness_data);
                                        if req.absolute_timelock < aggregated_soonest {
                                                aggregated_soonest = req.absolute_timelock;
                                        }
                                }
                        }
                }
                new_claims.push((aggregated_soonest, aggregated_claim));

                // Generate claim transactions and track them to bump if necessary at
                // height timer expiration (i.e in how many blocks we're going to take action).
                for (soonest_timelock, claim) in new_claims.drain(..) {
                        let mut claim_material = ClaimTxBumpMaterial { height_timer: None, feerate_previous: 0, soonest_timelock, per_input_material: claim };
                        if let Some((new_timer, new_feerate, tx)) = self.generate_claim_tx(height, &claim_material, &*fee_estimator, &*logger) {
                                claim_material.height_timer = new_timer;
                                claim_material.feerate_previous = new_feerate;
                                let txid = tx.txid();
                                for k in claim_material.per_input_material.keys() {
                                        log_trace!(logger, "Registering claiming request for {}:{}", k.txid, k.vout);
                                        self.claimable_outpoints.insert(k.clone(), (txid, height));
                                }
                                self.pending_claim_requests.insert(txid, claim_material);
                                log_trace!(logger, "Broadcast onchain {}", log_tx!(tx));
                                broadcaster.broadcast_transaction(&tx);
                        }
                }

                let mut bump_candidates = HashMap::new();
                for tx in txn_matched {
                        // Scan all input to verify is one of the outpoint spent is of interest for us
                        let mut claimed_outputs_material = Vec::new();
                        for inp in &tx.input {
                                if let Some(first_claim_txid_height) = self.claimable_outpoints.get(&inp.previous_output) {
                                        // If outpoint has claim request pending on it...
                                        if let Some(claim_material) = self.pending_claim_requests.get_mut(&first_claim_txid_height.0) {
                                                //... we need to verify equality between transaction outpoints and claim request
                                                // outpoints to know if transaction is the original claim or a bumped one issued
                                                // by us.
                                                let mut set_equality = true;
                                                if claim_material.per_input_material.len() != tx.input.len() {
                                                        set_equality = false;
                                                } else {
                                                        for (claim_inp, tx_inp) in claim_material.per_input_material.keys().zip(tx.input.iter()) {
                                                                if *claim_inp != tx_inp.previous_output {
                                                                        set_equality = false;
                                                                }
                                                        }
                                                }

                                                macro_rules! clean_claim_request_after_safety_delay {
                                                        () => {
                                                                let new_event = OnchainEvent::Claim { claim_request: first_claim_txid_height.0.clone() };
                                                                match self.onchain_events_waiting_threshold_conf.entry(height + ANTI_REORG_DELAY - 1) {
                                                                        hash_map::Entry::Occupied(mut entry) => {
                                                                                if !entry.get().contains(&new_event) {
                                                                                        entry.get_mut().push(new_event);
                                                                                }
                                                                        },
                                                                        hash_map::Entry::Vacant(entry) => {
                                                                                entry.insert(vec![new_event]);
                                                                        }
                                                                }
                                                        }
                                                }

                                                // If this is our transaction (or our counterparty spent all the outputs
                                                // before we could anyway with same inputs order than us), wait for
                                                // ANTI_REORG_DELAY and clean the RBF tracking map.
                                                if set_equality {
                                                        clean_claim_request_after_safety_delay!();
                                                } else { // If false, generate new claim request with update outpoint set
                                                        let mut at_least_one_drop = false;
                                                        for input in tx.input.iter() {
                                                                if let Some(input_material) = claim_material.per_input_material.remove(&input.previous_output) {
                                                                        claimed_outputs_material.push((input.previous_output, input_material));
                                                                        at_least_one_drop = true;
                                                                }
                                                                // If there are no outpoints left to claim in this request, drop it entirely after ANTI_REORG_DELAY.
                                                                if claim_material.per_input_material.is_empty() {
                                                                        clean_claim_request_after_safety_delay!();
                                                                }
                                                        }
                                                        //TODO: recompute soonest_timelock to avoid wasting a bit on fees
                                                        if at_least_one_drop {
                                                                bump_candidates.insert(first_claim_txid_height.0.clone(), claim_material.clone());
                                                        }
                                                }
                                                break; //No need to iterate further, either tx is our or their
                                        } else {
                                                panic!("Inconsistencies between pending_claim_requests map and claimable_outpoints map");
                                        }
                                }
                        }
                        for (outpoint, input_material) in claimed_outputs_material.drain(..) {
                                let new_event = OnchainEvent::ContentiousOutpoint { outpoint, input_material };
                                match self.onchain_events_waiting_threshold_conf.entry(height + ANTI_REORG_DELAY - 1) {
                                        hash_map::Entry::Occupied(mut entry) => {
                                                if !entry.get().contains(&new_event) {
                                                        entry.get_mut().push(new_event);
                                                }
                                        },
                                        hash_map::Entry::Vacant(entry) => {
                                                entry.insert(vec![new_event]);
                                        }
                                }
                        }
                }

                // After security delay, either our claim tx got enough confs or outpoint is definetely out of reach
                if let Some(events) = self.onchain_events_waiting_threshold_conf.remove(&height) {
                        for ev in events {
                                match ev {
                                        OnchainEvent::Claim { claim_request } => {
                                                // We may remove a whole set of claim outpoints here, as these one may have
                                                // been aggregated in a single tx and claimed so atomically
                                                if let Some(bump_material) = self.pending_claim_requests.remove(&claim_request) {
                                                        for outpoint in bump_material.per_input_material.keys() {
                                                                self.claimable_outpoints.remove(&outpoint);
                                                        }
                                                }
                                        },
                                        OnchainEvent::ContentiousOutpoint { outpoint, .. } => {
                                                self.claimable_outpoints.remove(&outpoint);
                                        }
                                }
                        }
                }

                // Check if any pending claim request must be rescheduled
                for (first_claim_txid, ref claim_data) in self.pending_claim_requests.iter() {
                        if let Some(h) = claim_data.height_timer {
                                if h == height {
                                        bump_candidates.insert(*first_claim_txid, (*claim_data).clone());
                                }
                        }
                }

                // Build, bump and rebroadcast tx accordingly
                log_trace!(logger, "Bumping {} candidates", bump_candidates.len());
                for (first_claim_txid, claim_material) in bump_candidates.iter() {
                        if let Some((new_timer, new_feerate, bump_tx)) = self.generate_claim_tx(height, &claim_material, &*fee_estimator, &*logger) {
                                log_trace!(logger, "Broadcast onchain {}", log_tx!(bump_tx));
                                broadcaster.broadcast_transaction(&bump_tx);
                                if let Some(claim_material) = self.pending_claim_requests.get_mut(first_claim_txid) {
                                        claim_material.height_timer = new_timer;
                                        claim_material.feerate_previous = new_feerate;
                                }
                        }
                }
        }

        pub(super) fn block_disconnected<B: Deref, F: Deref, L: Deref>(&mut self, height: u32, broadcaster: B, fee_estimator: F, logger: L)
                where B::Target: BroadcasterInterface,
                      F::Target: FeeEstimator,
                                        L::Target: Logger,
        {
                let mut bump_candidates = HashMap::new();
                if let Some(events) = self.onchain_events_waiting_threshold_conf.remove(&(height + ANTI_REORG_DELAY - 1)) {
                        //- our claim tx on a commitment tx output
                        //- resurect outpoint back in its claimable set and regenerate tx
                        for ev in events {
                                match ev {
                                        OnchainEvent::ContentiousOutpoint { outpoint, input_material } => {
                                                if let Some(ancestor_claimable_txid) = self.claimable_outpoints.get(&outpoint) {
                                                        if let Some(claim_material) = self.pending_claim_requests.get_mut(&ancestor_claimable_txid.0) {
                                                                claim_material.per_input_material.insert(outpoint, input_material);
                                                                // Using a HashMap guarantee us than if we have multiple outpoints getting
                                                                // resurrected only one bump claim tx is going to be broadcast
                                                                bump_candidates.insert(ancestor_claimable_txid.clone(), claim_material.clone());
                                                        }
                                                }
                                        },
                                        _ => {},
                                }
                        }
                }
                for (_, claim_material) in bump_candidates.iter_mut() {
                        if let Some((new_timer, new_feerate, bump_tx)) = self.generate_claim_tx(height, &claim_material, &*fee_estimator, &*logger) {
                                claim_material.height_timer = new_timer;
                                claim_material.feerate_previous = new_feerate;
                                broadcaster.broadcast_transaction(&bump_tx);
                        }
                }
                for (ancestor_claim_txid, claim_material) in bump_candidates.drain() {
                        self.pending_claim_requests.insert(ancestor_claim_txid.0, claim_material);
                }
                //TODO: if we implement cross-block aggregated claim transaction we need to refresh set of outpoints and regenerate tx but
                // right now if one of the outpoint get disconnected, just erase whole pending claim request.
                let mut remove_request = Vec::new();
                self.claimable_outpoints.retain(|_, ref v|
                        if v.1 == height {
                        remove_request.push(v.0.clone());
                        false
                        } else { true });
                for req in remove_request {
                        self.pending_claim_requests.remove(&req);
                }
        }

        pub(super) fn provide_latest_local_tx(&mut self, tx: LocalCommitmentTransaction) -> Result<(), ()> {
                // To prevent any unsafe state discrepancy between offchain and onchain, once local
                // commitment transaction has been signed due to an event (either block height for
                // HTLC-timeout or channel force-closure), don't allow any further update of local
                // commitment transaction view to avoid delivery of revocation secret to counterparty
                // for the aformentionned signed transaction.
                if self.local_htlc_sigs.is_some() || self.prev_local_htlc_sigs.is_some() {
                        return Err(());
                }
                self.prev_local_commitment = self.local_commitment.take();
                self.local_commitment = Some(tx);
                Ok(())
        }

        fn sign_latest_local_htlcs(&mut self) {
                if let Some(ref local_commitment) = self.local_commitment {
                        if let Ok(sigs) = self.key_storage.sign_local_commitment_htlc_transactions(local_commitment, self.local_csv, &self.secp_ctx) {
                                self.local_htlc_sigs = Some(Vec::new());
                                let ret = self.local_htlc_sigs.as_mut().unwrap();
                                for (htlc_idx, (local_sig, &(ref htlc, _))) in sigs.iter().zip(local_commitment.per_htlc.iter()).enumerate() {
                                        if let Some(tx_idx) = htlc.transaction_output_index {
                                                if ret.len() <= tx_idx as usize { ret.resize(tx_idx as usize + 1, None); }
                                                ret[tx_idx as usize] = Some((htlc_idx, local_sig.expect("Did not receive a signature for a non-dust HTLC")));
                                        } else {
                                                assert!(local_sig.is_none(), "Received a signature for a dust HTLC");
                                        }
                                }
                        }
                }
        }
        fn sign_prev_local_htlcs(&mut self) {
                if let Some(ref local_commitment) = self.prev_local_commitment {
                        if let Ok(sigs) = self.key_storage.sign_local_commitment_htlc_transactions(local_commitment, self.local_csv, &self.secp_ctx) {
                                self.prev_local_htlc_sigs = Some(Vec::new());
                                let ret = self.prev_local_htlc_sigs.as_mut().unwrap();
                                for (htlc_idx, (local_sig, &(ref htlc, _))) in sigs.iter().zip(local_commitment.per_htlc.iter()).enumerate() {
                                        if let Some(tx_idx) = htlc.transaction_output_index {
                                                if ret.len() <= tx_idx as usize { ret.resize(tx_idx as usize + 1, None); }
                                                ret[tx_idx as usize] = Some((htlc_idx, local_sig.expect("Did not receive a signature for a non-dust HTLC")));
                                        } else {
                                                assert!(local_sig.is_none(), "Received a signature for a dust HTLC");
                                        }
                                }
                        }
                }
        }

        //TODO: getting lastest local transactions should be infaillible and result in us "force-closing the channel", but we may
        // have empty local commitment transaction if a ChannelMonitor is asked to force-close just after Channel::get_outbound_funding_created,
        // before providing a initial commitment transaction. For outbound channel, init ChannelMonitor at Channel::funding_signed, there is nothing
        // to monitor before.
        pub(super) fn get_fully_signed_local_tx(&mut self, funding_redeemscript: &Script) -> Option<Transaction> {
                if let Some(ref mut local_commitment) = self.local_commitment {
                        match self.key_storage.sign_local_commitment(local_commitment, &self.secp_ctx) {
                                Ok(sig) => Some(local_commitment.add_local_sig(funding_redeemscript, sig)),
                                Err(_) => return None,
                        }
                } else {
                        None
                }
        }

        #[cfg(test)]
        pub(super) fn get_fully_signed_copy_local_tx(&mut self, funding_redeemscript: &Script) -> Option<Transaction> {
                if let Some(ref mut local_commitment) = self.local_commitment {
                        let local_commitment = local_commitment.clone();
                        match self.key_storage.sign_local_commitment(&local_commitment, &self.secp_ctx) {
                                Ok(sig) => Some(local_commitment.add_local_sig(funding_redeemscript, sig)),
                                Err(_) => return None,
                        }
                } else {
                        None
                }
        }

        pub(super) fn get_fully_signed_htlc_tx(&mut self, outp: &::bitcoin::OutPoint, preimage: &Option<PaymentPreimage>) -> Option<Transaction> {
                let mut htlc_tx = None;
                if self.local_commitment.is_some() {
                        let commitment_txid = self.local_commitment.as_ref().unwrap().txid();
                        if commitment_txid == outp.txid {
                                self.sign_latest_local_htlcs();
                                if let &Some(ref htlc_sigs) = &self.local_htlc_sigs {
                                        let &(ref htlc_idx, ref htlc_sig) = htlc_sigs[outp.vout as usize].as_ref().unwrap();
                                        htlc_tx = Some(self.local_commitment.as_ref().unwrap()
                                                .get_signed_htlc_tx(*htlc_idx, htlc_sig, preimage, self.local_csv));
                                }
                        }
                }
                if self.prev_local_commitment.is_some() {
                        let commitment_txid = self.prev_local_commitment.as_ref().unwrap().txid();
                        if commitment_txid == outp.txid {
                                self.sign_prev_local_htlcs();
                                if let &Some(ref htlc_sigs) = &self.prev_local_htlc_sigs {
                                        let &(ref htlc_idx, ref htlc_sig) = htlc_sigs[outp.vout as usize].as_ref().unwrap();
                                        htlc_tx = Some(self.prev_local_commitment.as_ref().unwrap()
                                                .get_signed_htlc_tx(*htlc_idx, htlc_sig, preimage, self.local_csv));
                                }
                        }
                }
                htlc_tx
        }

        #[cfg(test)]
        pub(super) fn unsafe_get_fully_signed_htlc_tx(&mut self, outp: &::bitcoin::OutPoint, preimage: &Option<PaymentPreimage>) -> Option<Transaction> {
                let latest_had_sigs = self.local_htlc_sigs.is_some();
                let prev_had_sigs = self.prev_local_htlc_sigs.is_some();
                let ret = self.get_fully_signed_htlc_tx(outp, preimage);
                if !latest_had_sigs {
                        self.local_htlc_sigs = None;
                }
                if !prev_had_sigs {
                        self.prev_local_htlc_sigs = None;
                }
                ret
        }
}