Reduce force-closures with user fee estimators which round poorly
[rust-lightning] / lightning / src / ln / channel.rs
index e39478bd740c063ce1f29a7dc853238ec75fcf48..0ab687521c3aa5fcff317b1c53ee65e58022dcda 100644 (file)
@@ -32,9 +32,10 @@ use ln::chan_utils::{CounterpartyCommitmentSecrets, TxCreationKeys, HTLCOutputIn
 use ln::chan_utils;
 use chain::BestBlock;
 use chain::chaininterface::{FeeEstimator,ConfirmationTarget};
-use chain::channelmonitor::{ChannelMonitor, ChannelMonitorUpdate, ChannelMonitorUpdateStep, HTLC_FAIL_BACK_BUFFER};
+use chain::channelmonitor::{ChannelMonitor, ChannelMonitorUpdate, ChannelMonitorUpdateStep, LATENCY_GRACE_PERIOD_BLOCKS};
 use chain::transaction::{OutPoint, TransactionData};
 use chain::keysinterface::{Sign, KeysInterface};
+use util::events::ClosureReason;
 use util::ser::{Readable, ReadableArgs, Writeable, Writer, VecWriter};
 use util::logger::Logger;
 use util::errors::APIError;
@@ -61,7 +62,7 @@ pub struct ChannelValueStat {
        pub counterparty_dust_limit_msat: u64,
 }
 
-#[derive(Clone, Copy, PartialEq)]
+#[derive(Debug, Clone, Copy, PartialEq)]
 enum FeeUpdateState {
        // Inbound states mirroring InboundHTLCState
        RemoteAnnounced,
@@ -292,6 +293,19 @@ struct HTLCStats {
        pending_htlcs_value_msat: u64,
        on_counterparty_tx_dust_exposure_msat: u64,
        on_holder_tx_dust_exposure_msat: u64,
+       holding_cell_msat: u64,
+       on_holder_tx_holding_cell_htlcs_count: u32, // dust HTLCs *non*-included
+}
+
+/// An enum gathering stats on commitment transaction, either local or remote.
+struct CommitmentStats<'a> {
+       tx: CommitmentTransaction, // the transaction info
+       feerate_per_kw: u32, // the feerate included to build the transaction
+       total_fee_sat: u64, // the total fee included in the transaction
+       num_nondust_htlcs: usize,  // the number of HTLC outputs (dust HTLCs *non*-included)
+       htlcs_included: Vec<(HTLCOutputInCommitment, Option<&'a HTLCSource>)>, // the list of HTLCs (dust HTLCs *included*) which were not ignored when building the transaction
+       local_balance_msat: u64, // local balance before fees but considering dust limits
+       remote_balance_msat: u64, // remote balance before fees but considering dust limits
 }
 
 /// Used when calculating whether we or the remote can afford an additional HTLC.
@@ -373,11 +387,32 @@ pub(super) struct MonitorRestoreUpdates {
 /// the channel. Sadly, there isn't really a good number for this - if we expect to have no new
 /// HTLCs for days we may need this to suffice for feerate increases across days, but that may
 /// leave the channel less usable as we hold a bigger reserve.
-#[cfg(fuzzing)]
+#[cfg(any(fuzzing, test))]
 pub const FEE_SPIKE_BUFFER_FEE_INCREASE_MULTIPLE: u64 = 2;
-#[cfg(not(fuzzing))]
+#[cfg(not(any(fuzzing, test)))]
 const FEE_SPIKE_BUFFER_FEE_INCREASE_MULTIPLE: u64 = 2;
 
+/// If we fail to see a funding transaction confirmed on-chain within this many blocks after the
+/// channel creation on an inbound channel, we simply force-close and move on.
+/// This constant is the one suggested in BOLT 2.
+pub(crate) const FUNDING_CONF_DEADLINE_BLOCKS: u32 = 2016;
+
+/// In case of a concurrent update_add_htlc proposed by our counterparty, we might
+/// not have enough balance value remaining to cover the onchain cost of this new
+/// HTLC weight. If this happens, our counterparty fails the reception of our
+/// commitment_signed including this new HTLC due to infringement on the channel
+/// reserve.
+/// To prevent this case, we compute our outbound update_fee with an HTLC buffer of
+/// size 2. However, if the number of concurrent update_add_htlc is higher, this still
+/// leads to a channel force-close. Ultimately, this is an issue coming from the
+/// design of LN state machines, allowing asynchronous updates.
+pub(crate) const CONCURRENT_INBOUND_HTLC_FEE_BUFFER: u32 = 2;
+
+/// When a channel is opened, we check that the funding amount is enough to pay for relevant
+/// commitment transaction fees, with at least this many HTLCs present on the commitment
+/// transaction (not counting the value of the HTLCs themselves).
+pub(crate) const MIN_AFFORDABLE_HTLC_COUNT: usize = 4;
+
 // TODO: We should refactor this to be an Inbound/OutboundChannel until initial setup handshaking
 // has been completed, and then turn into a Channel to get compiler-time enforcement of things like
 // calling channel_id() before we're set up or things like get_outbound_funding_signed on an
@@ -475,20 +510,36 @@ pub(super) struct Channel<Signer: Sign> {
        funding_tx_confirmed_in: Option<BlockHash>,
        funding_tx_confirmation_height: u32,
        short_channel_id: Option<u64>,
+       /// Either the height at which this channel was created or the height at which it was last
+       /// serialized if it was serialized by versions prior to 0.0.103.
+       /// We use this to close if funding is never broadcasted.
+       channel_creation_height: u32,
 
        counterparty_dust_limit_satoshis: u64,
+
        #[cfg(test)]
        pub(super) holder_dust_limit_satoshis: u64,
        #[cfg(not(test))]
        holder_dust_limit_satoshis: u64,
+
        #[cfg(test)]
        pub(super) counterparty_max_htlc_value_in_flight_msat: u64,
        #[cfg(not(test))]
        counterparty_max_htlc_value_in_flight_msat: u64,
-       //get_holder_max_htlc_value_in_flight_msat(): u64,
+
+       #[cfg(test)]
+       pub(super) holder_max_htlc_value_in_flight_msat: u64,
+       #[cfg(not(test))]
+       holder_max_htlc_value_in_flight_msat: u64,
+
        /// minimum channel reserve for self to maintain - set by them.
        counterparty_selected_channel_reserve_satoshis: Option<u64>,
-       // get_holder_selected_channel_reserve_satoshis(channel_value_sats: u64): u64
+
+       #[cfg(test)]
+       pub(super) holder_selected_channel_reserve_satoshis: u64,
+       #[cfg(not(test))]
+       holder_selected_channel_reserve_satoshis: u64,
+
        counterparty_htlc_minimum_msat: u64,
        holder_htlc_minimum_msat: u64,
        #[cfg(test)]
@@ -640,13 +691,24 @@ impl<Signer: Sign> Channel<Signer> {
        /// required by us.
        ///
        /// Guaranteed to return a value no larger than channel_value_satoshis
+       ///
+       /// This is used both for new channels and to figure out what reserve value we sent to peers
+       /// for channels serialized before we included our selected reserve value in the serialized
+       /// data explicitly.
        pub(crate) fn get_holder_selected_channel_reserve_satoshis(channel_value_satoshis: u64) -> u64 {
                let (q, _) = channel_value_satoshis.overflowing_div(100);
                cmp::min(channel_value_satoshis, cmp::max(q, 1000)) //TODO
        }
 
+       pub(crate) fn opt_anchors(&self) -> bool {
+               self.channel_transaction_parameters.opt_anchors.is_some()
+       }
+
        // Constructors:
-       pub fn new_outbound<K: Deref, F: Deref>(fee_estimator: &F, keys_provider: &K, counterparty_node_id: PublicKey, their_features: &InitFeatures, channel_value_satoshis: u64, push_msat: u64, user_id: u64, config: &UserConfig) -> Result<Channel<Signer>, APIError>
+       pub fn new_outbound<K: Deref, F: Deref>(
+               fee_estimator: &F, keys_provider: &K, counterparty_node_id: PublicKey, their_features: &InitFeatures,
+               channel_value_satoshis: u64, push_msat: u64, user_id: u64, config: &UserConfig, current_chain_height: u32
+       ) -> Result<Channel<Signer>, APIError>
        where K::Target: KeysInterface<Signer = Signer>,
              F::Target: FeeEstimator,
        {
@@ -671,6 +733,12 @@ impl<Signer: Sign> Channel<Signer> {
 
                let feerate = fee_estimator.get_est_sat_per_1000_weight(ConfirmationTarget::Normal);
 
+               let value_to_self_msat = channel_value_satoshis * 1000 - push_msat;
+               let commitment_tx_fee = Self::commit_tx_fee_msat(feerate, MIN_AFFORDABLE_HTLC_COUNT);
+               if value_to_self_msat < commitment_tx_fee {
+                       return Err(APIError::APIMisuseError{ err: format!("Funding amount ({}) can't even pay fee for initial commitment transaction fee of {}.", value_to_self_msat / 1000, commitment_tx_fee / 1000) });
+               }
+
                let mut secp_ctx = Secp256k1::new();
                secp_ctx.seeded_randomize(&keys_provider.get_secure_random_bytes());
 
@@ -701,7 +769,7 @@ impl<Signer: Sign> Channel<Signer> {
 
                        cur_holder_commitment_transaction_number: INITIAL_COMMITMENT_NUMBER,
                        cur_counterparty_commitment_transaction_number: INITIAL_COMMITMENT_NUMBER,
-                       value_to_self_msat: channel_value_satoshis * 1000 - push_msat,
+                       value_to_self_msat,
 
                        pending_inbound_htlcs: Vec::new(),
                        pending_outbound_htlcs: Vec::new(),
@@ -734,12 +802,15 @@ impl<Signer: Sign> Channel<Signer> {
                        funding_tx_confirmed_in: None,
                        funding_tx_confirmation_height: 0,
                        short_channel_id: None,
+                       channel_creation_height: current_chain_height,
 
                        feerate_per_kw: feerate,
                        counterparty_dust_limit_satoshis: 0,
                        holder_dust_limit_satoshis: MIN_CHAN_DUST_LIMIT_SATOSHIS,
                        counterparty_max_htlc_value_in_flight_msat: 0,
+                       holder_max_htlc_value_in_flight_msat: Self::get_holder_max_htlc_value_in_flight_msat(channel_value_satoshis),
                        counterparty_selected_channel_reserve_satoshis: None, // Filled in in accept_channel
+                       holder_selected_channel_reserve_satoshis,
                        counterparty_htlc_minimum_msat: 0,
                        holder_htlc_minimum_msat: if config.own_channel_config.our_htlc_minimum_msat == 0 { 1 } else { config.own_channel_config.our_htlc_minimum_msat },
                        counterparty_max_accepted_htlcs: 0,
@@ -752,7 +823,8 @@ impl<Signer: Sign> Channel<Signer> {
                                holder_selected_contest_delay: config.own_channel_config.our_to_self_delay,
                                is_outbound_from_holder: true,
                                counterparty_parameters: None,
-                               funding_outpoint: None
+                               funding_outpoint: None,
+                               opt_anchors: None,
                        },
                        funding_transaction: None,
 
@@ -790,8 +862,12 @@ impl<Signer: Sign> Channel<Signer> {
                where F::Target: FeeEstimator
        {
                let lower_limit = fee_estimator.get_est_sat_per_1000_weight(ConfirmationTarget::Background);
-               if feerate_per_kw < lower_limit {
-                       return Err(ChannelError::Close(format!("Peer's feerate much too low. Actual: {}. Our expected lower limit: {}", feerate_per_kw, lower_limit)));
+               // Some fee estimators round up to the next full sat/vbyte (ie 250 sats per kw), causing
+               // occasional issues with feerate disagreements between an initiator that wants a feerate
+               // of 1.1 sat/vbyte and a receiver that wants 1.1 rounded up to 2. Thus, we always add 250
+               // sat/kw before the comparison here.
+               if feerate_per_kw + 250 < lower_limit {
+                       return Err(ChannelError::Close(format!("Peer's feerate much too low. Actual: {}. Our expected lower limit: {} (- 250)", feerate_per_kw, lower_limit)));
                }
                // We only bound the fee updates on the upper side to prevent completely absurd feerates,
                // always accepting up to 25 sat/vByte or 10x our fee estimator's "High Priority" fee.
@@ -807,9 +883,13 @@ impl<Signer: Sign> Channel<Signer> {
 
        /// Creates a new channel from a remote sides' request for one.
        /// Assumes chain_hash has already been checked and corresponds with what we expect!
-       pub fn new_from_req<K: Deref, F: Deref>(fee_estimator: &F, keys_provider: &K, counterparty_node_id: PublicKey, their_features: &InitFeatures, msg: &msgs::OpenChannel, user_id: u64, config: &UserConfig) -> Result<Channel<Signer>, ChannelError>
+       pub fn new_from_req<K: Deref, F: Deref, L: Deref>(
+               fee_estimator: &F, keys_provider: &K, counterparty_node_id: PublicKey, their_features: &InitFeatures,
+               msg: &msgs::OpenChannel, user_id: u64, config: &UserConfig, current_chain_height: u32, logger: &L
+       ) -> Result<Channel<Signer>, ChannelError>
                where K::Target: KeysInterface<Signer = Signer>,
-          F::Target: FeeEstimator
+                     F::Target: FeeEstimator,
+                     L::Target: Logger,
        {
                // First check the channel type is known, failing before we do anything else if we don't
                // support this channel type.
@@ -857,9 +937,6 @@ impl<Signer: Sign> Channel<Signer> {
                if msg.dust_limit_satoshis > msg.funding_satoshis {
                        return Err(ChannelError::Close(format!("dust_limit_satoshis {} was larger than funding_satoshis {}. Peer never wants payout outputs?", msg.dust_limit_satoshis, msg.funding_satoshis)));
                }
-               if msg.dust_limit_satoshis > msg.channel_reserve_satoshis {
-                       return Err(ChannelError::Close(format!("Bogus; channel reserve ({}) is less than dust limit ({})", msg.channel_reserve_satoshis, msg.dust_limit_satoshis)));
-               }
                let full_channel_value_msat = (msg.funding_satoshis - msg.channel_reserve_satoshis) * 1000;
                if msg.htlc_minimum_msat >= full_channel_value_msat {
                        return Err(ChannelError::Close(format!("Minimum htlc value ({}) was larger than full channel value ({})", msg.htlc_minimum_msat, full_channel_value_msat)));
@@ -911,31 +988,31 @@ impl<Signer: Sign> Channel<Signer> {
                // we either accept their preference or the preferences match
                local_config.announced_channel = announce;
 
-               let background_feerate = fee_estimator.get_est_sat_per_1000_weight(ConfirmationTarget::Background);
-
                let holder_selected_channel_reserve_satoshis = Channel::<Signer>::get_holder_selected_channel_reserve_satoshis(msg.funding_satoshis);
                if holder_selected_channel_reserve_satoshis < MIN_CHAN_DUST_LIMIT_SATOSHIS {
                        return Err(ChannelError::Close(format!("Suitable channel reserve not found. remote_channel_reserve was ({}). dust_limit_satoshis is ({}).", holder_selected_channel_reserve_satoshis, MIN_CHAN_DUST_LIMIT_SATOSHIS)));
                }
                if msg.channel_reserve_satoshis < MIN_CHAN_DUST_LIMIT_SATOSHIS {
-                       return Err(ChannelError::Close(format!("channel_reserve_satoshis ({}) is smaller than our dust limit ({})", msg.channel_reserve_satoshis, MIN_CHAN_DUST_LIMIT_SATOSHIS)));
+                       log_debug!(logger, "channel_reserve_satoshis ({}) is smaller than our dust limit ({}). We can broadcast stale states without any risk, implying this channel is very insecure for our counterparty.",
+                               msg.channel_reserve_satoshis, MIN_CHAN_DUST_LIMIT_SATOSHIS);
                }
                if holder_selected_channel_reserve_satoshis < msg.dust_limit_satoshis {
                        return Err(ChannelError::Close(format!("Dust limit ({}) too high for the channel reserve we require the remote to keep ({})", msg.dust_limit_satoshis, holder_selected_channel_reserve_satoshis)));
                }
 
                // check if the funder's amount for the initial commitment tx is sufficient
-               // for full fee payment
+               // for full fee payment plus a few HTLCs to ensure the channel will be useful.
                let funders_amount_msat = msg.funding_satoshis * 1000 - msg.push_msat;
-               let lower_limit = background_feerate as u64 * COMMITMENT_TX_BASE_WEIGHT;
-               if funders_amount_msat < lower_limit {
-                       return Err(ChannelError::Close(format!("Insufficient funding amount ({}) for initial commitment. Must be at least {}", funders_amount_msat, lower_limit)));
+               let commitment_tx_fee = Self::commit_tx_fee_msat(msg.feerate_per_kw, MIN_AFFORDABLE_HTLC_COUNT) / 1000;
+               if funders_amount_msat / 1000 < commitment_tx_fee {
+                       return Err(ChannelError::Close(format!("Funding amount ({} sats) can't even pay fee for initial commitment transaction fee of {} sats.", funders_amount_msat / 1000, commitment_tx_fee)));
                }
 
-               let to_local_msat = msg.push_msat;
-               let to_remote_msat = funders_amount_msat - background_feerate as u64 * COMMITMENT_TX_BASE_WEIGHT;
-               if to_local_msat <= msg.channel_reserve_satoshis * 1000 && to_remote_msat <= holder_selected_channel_reserve_satoshis * 1000 {
-                       return Err(ChannelError::Close("Insufficient funding amount for initial commitment".to_owned()));
+               let to_remote_satoshis = funders_amount_msat / 1000 - commitment_tx_fee;
+               // While it's reasonable for us to not meet the channel reserve initially (if they don't
+               // want to push much to us), our counterparty should always have more than our reserve.
+               if to_remote_satoshis < holder_selected_channel_reserve_satoshis {
+                       return Err(ChannelError::Close("Insufficient funding amount for initial reserve".to_owned()));
                }
 
                let counterparty_shutdown_scriptpubkey = if their_features.supports_upfront_shutdown_script() {
@@ -1020,13 +1097,16 @@ impl<Signer: Sign> Channel<Signer> {
                        funding_tx_confirmed_in: None,
                        funding_tx_confirmation_height: 0,
                        short_channel_id: None,
+                       channel_creation_height: current_chain_height,
 
                        feerate_per_kw: msg.feerate_per_kw,
                        channel_value_satoshis: msg.funding_satoshis,
                        counterparty_dust_limit_satoshis: msg.dust_limit_satoshis,
                        holder_dust_limit_satoshis: MIN_CHAN_DUST_LIMIT_SATOSHIS,
                        counterparty_max_htlc_value_in_flight_msat: cmp::min(msg.max_htlc_value_in_flight_msat, msg.funding_satoshis * 1000),
+                       holder_max_htlc_value_in_flight_msat: Self::get_holder_max_htlc_value_in_flight_msat(msg.funding_satoshis),
                        counterparty_selected_channel_reserve_satoshis: Some(msg.channel_reserve_satoshis),
+                       holder_selected_channel_reserve_satoshis,
                        counterparty_htlc_minimum_msat: msg.htlc_minimum_msat,
                        holder_htlc_minimum_msat: if config.own_channel_config.our_htlc_minimum_msat == 0 { 1 } else { config.own_channel_config.our_htlc_minimum_msat },
                        counterparty_max_accepted_htlcs: msg.max_accepted_htlcs,
@@ -1042,7 +1122,8 @@ impl<Signer: Sign> Channel<Signer> {
                                        selected_contest_delay: msg.to_self_delay,
                                        pubkeys: counterparty_pubkeys,
                                }),
-                               funding_outpoint: None
+                               funding_outpoint: None,
+                               opt_anchors: None
                        },
                        funding_transaction: None,
 
@@ -1088,12 +1169,10 @@ impl<Signer: Sign> Channel<Signer> {
        /// have not yet committed it. Such HTLCs will only be included in transactions which are being
        /// generated by the peer which proposed adding the HTLCs, and thus we need to understand both
        /// which peer generated this transaction and "to whom" this transaction flows.
-       /// Returns (the transaction info, the number of HTLC outputs which were present in the
-       /// transaction, the list of HTLCs which were not ignored when building the transaction).
-       /// Note that below-dust HTLCs are included in the fourth return value, but not the third, and
-       /// sources are provided only for outbound HTLCs in the fourth return value.
        #[inline]
-       fn build_commitment_transaction<L: Deref>(&self, commitment_number: u64, keys: &TxCreationKeys, local: bool, generated_by_local: bool, logger: &L) -> (CommitmentTransaction, u32, usize, Vec<(HTLCOutputInCommitment, Option<&HTLCSource>)>) where L::Target: Logger {
+       fn build_commitment_transaction<L: Deref>(&self, commitment_number: u64, keys: &TxCreationKeys, local: bool, generated_by_local: bool, logger: &L) -> CommitmentStats
+               where L::Target: Logger
+       {
                let mut included_dust_htlcs: Vec<(HTLCOutputInCommitment, Option<&HTLCSource>)> = Vec::new();
                let num_htlcs = self.pending_inbound_htlcs.len() + self.pending_outbound_htlcs.len();
                let mut included_non_dust_htlcs: Vec<(HTLCOutputInCommitment, Option<&HTLCSource>)> = Vec::with_capacity(num_htlcs);
@@ -1212,13 +1291,13 @@ impl<Signer: Sign> Channel<Signer> {
                        }
                }
 
-               let value_to_self_msat: i64 = (self.value_to_self_msat - local_htlc_total_msat) as i64 + value_to_self_msat_offset;
+               let mut value_to_self_msat: i64 = (self.value_to_self_msat - local_htlc_total_msat) as i64 + value_to_self_msat_offset;
                assert!(value_to_self_msat >= 0);
                // Note that in case they have several just-awaiting-last-RAA fulfills in-progress (ie
                // AwaitingRemoteRevokeToRemove or AwaitingRemovedRemoteRevoke) we may have allowed them to
                // "violate" their reserve value by couting those against it. Thus, we have to convert
                // everything to i64 before subtracting as otherwise we can overflow.
-               let value_to_remote_msat: i64 = (self.channel_value_satoshis * 1000) as i64 - (self.value_to_self_msat as i64) - (remote_htlc_total_msat as i64) - value_to_self_msat_offset;
+               let mut value_to_remote_msat: i64 = (self.channel_value_satoshis * 1000) as i64 - (self.value_to_self_msat as i64) - (remote_htlc_total_msat as i64) - value_to_self_msat_offset;
                assert!(value_to_remote_msat >= 0);
 
                #[cfg(debug_assertions)]
@@ -1232,15 +1311,15 @@ impl<Signer: Sign> Channel<Signer> {
                        };
                        debug_assert!(broadcaster_max_commitment_tx_output.0 <= value_to_self_msat as u64 || value_to_self_msat / 1000 >= self.counterparty_selected_channel_reserve_satoshis.unwrap() as i64);
                        broadcaster_max_commitment_tx_output.0 = cmp::max(broadcaster_max_commitment_tx_output.0, value_to_self_msat as u64);
-                       debug_assert!(broadcaster_max_commitment_tx_output.1 <= value_to_remote_msat as u64 || value_to_remote_msat / 1000 >= Channel::<Signer>::get_holder_selected_channel_reserve_satoshis(self.channel_value_satoshis) as i64);
+                       debug_assert!(broadcaster_max_commitment_tx_output.1 <= value_to_remote_msat as u64 || value_to_remote_msat / 1000 >= self.holder_selected_channel_reserve_satoshis as i64);
                        broadcaster_max_commitment_tx_output.1 = cmp::max(broadcaster_max_commitment_tx_output.1, value_to_remote_msat as u64);
                }
 
-               let total_fee = feerate_per_kw as u64 * (COMMITMENT_TX_BASE_WEIGHT + (included_non_dust_htlcs.len() as u64) * COMMITMENT_TX_WEIGHT_PER_HTLC) / 1000;
+               let total_fee_sat = Channel::<Signer>::commit_tx_fee_sat(feerate_per_kw, included_non_dust_htlcs.len());
                let (value_to_self, value_to_remote) = if self.is_outbound() {
-                       (value_to_self_msat / 1000 - total_fee as i64, value_to_remote_msat / 1000)
+                       (value_to_self_msat / 1000 - total_fee_sat as i64, value_to_remote_msat / 1000)
                } else {
-                       (value_to_self_msat / 1000, value_to_remote_msat / 1000 - total_fee as i64)
+                       (value_to_self_msat / 1000, value_to_remote_msat / 1000 - total_fee_sat as i64)
                };
 
                let mut value_to_a = if local { value_to_self } else { value_to_remote };
@@ -1271,7 +1350,7 @@ impl<Signer: Sign> Channel<Signer> {
                let tx = CommitmentTransaction::new_with_auxiliary_htlc_data(commitment_number,
                                                                             value_to_a as u64,
                                                                             value_to_b as u64,
-                                                                            false,
+                                                                            self.channel_transaction_parameters.opt_anchors.is_some(),
                                                                             funding_pubkey_a,
                                                                             funding_pubkey_b,
                                                                             keys.clone(),
@@ -1284,7 +1363,19 @@ impl<Signer: Sign> Channel<Signer> {
                htlcs_included.sort_unstable_by_key(|h| h.0.transaction_output_index.unwrap());
                htlcs_included.append(&mut included_dust_htlcs);
 
-               (tx, feerate_per_kw, num_nondust_htlcs, htlcs_included)
+               // For the stats, trimmed-to-0 the value in msats accordingly
+               value_to_self_msat = if (value_to_self_msat * 1000) < broadcaster_dust_limit_satoshis as i64 { 0 } else { value_to_self_msat };
+               value_to_remote_msat = if (value_to_remote_msat * 1000) < broadcaster_dust_limit_satoshis as i64 { 0 } else { value_to_remote_msat };
+
+               CommitmentStats {
+                       tx,
+                       feerate_per_kw,
+                       total_fee_sat,
+                       num_nondust_htlcs,
+                       htlcs_included,
+                       local_balance_msat: value_to_self_msat as u64,
+                       remote_balance_msat: value_to_remote_msat as u64,
+               }
        }
 
        #[inline]
@@ -1635,12 +1726,8 @@ impl<Signer: Sign> Channel<Signer> {
                if msg.channel_reserve_satoshis > self.channel_value_satoshis {
                        return Err(ChannelError::Close(format!("Bogus channel_reserve_satoshis ({}). Must not be greater than ({})", msg.channel_reserve_satoshis, self.channel_value_satoshis)));
                }
-               if msg.channel_reserve_satoshis < self.holder_dust_limit_satoshis {
-                       return Err(ChannelError::Close(format!("Peer never wants payout outputs? channel_reserve_satoshis was ({}). dust_limit is ({})", msg.channel_reserve_satoshis, self.holder_dust_limit_satoshis)));
-               }
-               let remote_reserve = Channel::<Signer>::get_holder_selected_channel_reserve_satoshis(self.channel_value_satoshis);
-               if msg.dust_limit_satoshis > remote_reserve {
-                       return Err(ChannelError::Close(format!("Dust limit ({}) is bigger than our channel reserve ({})", msg.dust_limit_satoshis, remote_reserve)));
+               if msg.dust_limit_satoshis > self.holder_selected_channel_reserve_satoshis {
+                       return Err(ChannelError::Close(format!("Dust limit ({}) is bigger than our channel reserve ({})", msg.dust_limit_satoshis, self.holder_selected_channel_reserve_satoshis)));
                }
                let full_channel_value_msat = (self.channel_value_satoshis - msg.channel_reserve_satoshis) * 1000;
                if msg.htlc_minimum_msat >= full_channel_value_msat {
@@ -1738,7 +1825,7 @@ impl<Signer: Sign> Channel<Signer> {
                let funding_script = self.get_funding_redeemscript();
 
                let keys = self.build_holder_transaction_keys(self.cur_holder_commitment_transaction_number)?;
-               let initial_commitment_tx = self.build_commitment_transaction(self.cur_holder_commitment_transaction_number, &keys, true, false, logger).0;
+               let initial_commitment_tx = self.build_commitment_transaction(self.cur_holder_commitment_transaction_number, &keys, true, false, logger).tx;
                {
                        let trusted_tx = initial_commitment_tx.trust();
                        let initial_commitment_bitcoin_tx = trusted_tx.built_transaction();
@@ -1752,7 +1839,7 @@ impl<Signer: Sign> Channel<Signer> {
                }
 
                let counterparty_keys = self.build_remote_transaction_keys()?;
-               let counterparty_initial_commitment_tx = self.build_commitment_transaction(self.cur_counterparty_commitment_transaction_number, &counterparty_keys, false, false, logger).0;
+               let counterparty_initial_commitment_tx = self.build_commitment_transaction(self.cur_counterparty_commitment_transaction_number, &counterparty_keys, false, false, logger).tx;
 
                let counterparty_trusted_tx = counterparty_initial_commitment_tx.trust();
                let counterparty_initial_bitcoin_tx = counterparty_trusted_tx.built_transaction();
@@ -1863,7 +1950,7 @@ impl<Signer: Sign> Channel<Signer> {
                let funding_script = self.get_funding_redeemscript();
 
                let counterparty_keys = self.build_remote_transaction_keys()?;
-               let counterparty_initial_commitment_tx = self.build_commitment_transaction(self.cur_counterparty_commitment_transaction_number, &counterparty_keys, false, false, logger).0;
+               let counterparty_initial_commitment_tx = self.build_commitment_transaction(self.cur_counterparty_commitment_transaction_number, &counterparty_keys, false, false, logger).tx;
                let counterparty_trusted_tx = counterparty_initial_commitment_tx.trust();
                let counterparty_initial_bitcoin_tx = counterparty_trusted_tx.built_transaction();
 
@@ -1871,7 +1958,7 @@ impl<Signer: Sign> Channel<Signer> {
                        log_bytes!(self.channel_id()), counterparty_initial_bitcoin_tx.txid, encode::serialize_hex(&counterparty_initial_bitcoin_tx.transaction));
 
                let holder_signer = self.build_holder_transaction_keys(self.cur_holder_commitment_transaction_number)?;
-               let initial_commitment_tx = self.build_commitment_transaction(self.cur_holder_commitment_transaction_number, &holder_signer, true, false, logger).0;
+               let initial_commitment_tx = self.build_commitment_transaction(self.cur_holder_commitment_transaction_number, &holder_signer, true, false, logger).tx;
                {
                        let trusted_tx = initial_commitment_tx.trust();
                        let initial_commitment_bitcoin_tx = trusted_tx.built_transaction();
@@ -1966,16 +2053,18 @@ impl<Signer: Sign> Channel<Signer> {
        }
 
        /// Returns a HTLCStats about inbound pending htlcs
-       fn get_inbound_pending_htlc_stats(&self) -> HTLCStats {
+       fn get_inbound_pending_htlc_stats(&self, outbound_feerate_update: Option<u32>) -> HTLCStats {
                let mut stats = HTLCStats {
                        pending_htlcs: self.pending_inbound_htlcs.len() as u32,
                        pending_htlcs_value_msat: 0,
                        on_counterparty_tx_dust_exposure_msat: 0,
                        on_holder_tx_dust_exposure_msat: 0,
+                       holding_cell_msat: 0,
+                       on_holder_tx_holding_cell_htlcs_count: 0,
                };
 
-               let counterparty_dust_limit_timeout_sat = (self.get_dust_buffer_feerate() as u64 * HTLC_TIMEOUT_TX_WEIGHT / 1000) + self.counterparty_dust_limit_satoshis;
-               let holder_dust_limit_success_sat = (self.get_dust_buffer_feerate() as u64 * HTLC_SUCCESS_TX_WEIGHT / 1000) + self.holder_dust_limit_satoshis;
+               let counterparty_dust_limit_timeout_sat = (self.get_dust_buffer_feerate(outbound_feerate_update) as u64 * HTLC_TIMEOUT_TX_WEIGHT / 1000) + self.counterparty_dust_limit_satoshis;
+               let holder_dust_limit_success_sat = (self.get_dust_buffer_feerate(outbound_feerate_update) as u64 * HTLC_SUCCESS_TX_WEIGHT / 1000) + self.holder_dust_limit_satoshis;
                for ref htlc in self.pending_inbound_htlcs.iter() {
                        stats.pending_htlcs_value_msat += htlc.amount_msat;
                        if htlc.amount_msat / 1000 < counterparty_dust_limit_timeout_sat {
@@ -1989,16 +2078,18 @@ impl<Signer: Sign> Channel<Signer> {
        }
 
        /// Returns a HTLCStats about pending outbound htlcs, *including* pending adds in our holding cell.
-       fn get_outbound_pending_htlc_stats(&self) -> HTLCStats {
+       fn get_outbound_pending_htlc_stats(&self, outbound_feerate_update: Option<u32>) -> HTLCStats {
                let mut stats = HTLCStats {
                        pending_htlcs: self.pending_outbound_htlcs.len() as u32,
                        pending_htlcs_value_msat: 0,
                        on_counterparty_tx_dust_exposure_msat: 0,
                        on_holder_tx_dust_exposure_msat: 0,
+                       holding_cell_msat: 0,
+                       on_holder_tx_holding_cell_htlcs_count: 0,
                };
 
-               let counterparty_dust_limit_success_sat = (self.get_dust_buffer_feerate() as u64 * HTLC_SUCCESS_TX_WEIGHT / 1000) + self.counterparty_dust_limit_satoshis;
-               let holder_dust_limit_timeout_sat = (self.get_dust_buffer_feerate() as u64 * HTLC_TIMEOUT_TX_WEIGHT / 1000) + self.holder_dust_limit_satoshis;
+               let counterparty_dust_limit_success_sat = (self.get_dust_buffer_feerate(outbound_feerate_update) as u64 * HTLC_SUCCESS_TX_WEIGHT / 1000) + self.counterparty_dust_limit_satoshis;
+               let holder_dust_limit_timeout_sat = (self.get_dust_buffer_feerate(outbound_feerate_update) as u64 * HTLC_TIMEOUT_TX_WEIGHT / 1000) + self.holder_dust_limit_satoshis;
                for ref htlc in self.pending_outbound_htlcs.iter() {
                        stats.pending_htlcs_value_msat += htlc.amount_msat;
                        if htlc.amount_msat / 1000 < counterparty_dust_limit_success_sat {
@@ -2013,11 +2104,14 @@ impl<Signer: Sign> Channel<Signer> {
                        if let &HTLCUpdateAwaitingACK::AddHTLC { ref amount_msat, .. } = update {
                                stats.pending_htlcs += 1;
                                stats.pending_htlcs_value_msat += amount_msat;
+                               stats.holding_cell_msat += amount_msat;
                                if *amount_msat / 1000 < counterparty_dust_limit_success_sat {
                                        stats.on_counterparty_tx_dust_exposure_msat += amount_msat;
                                }
                                if *amount_msat / 1000 < holder_dust_limit_timeout_sat {
                                        stats.on_holder_tx_dust_exposure_msat += amount_msat;
+                               } else {
+                                       stats.on_holder_tx_holding_cell_htlcs_count += 1;
                                }
                        }
                }
@@ -2033,27 +2127,33 @@ impl<Signer: Sign> Channel<Signer> {
                (
                        cmp::max(self.channel_value_satoshis as i64 * 1000
                                - self.value_to_self_msat as i64
-                               - self.get_inbound_pending_htlc_stats().pending_htlcs_value_msat as i64
-                               - Self::get_holder_selected_channel_reserve_satoshis(self.channel_value_satoshis) as i64 * 1000,
+                               - self.get_inbound_pending_htlc_stats(None).pending_htlcs_value_msat as i64
+                               - self.holder_selected_channel_reserve_satoshis as i64 * 1000,
                        0) as u64,
                        cmp::max(self.value_to_self_msat as i64
-                               - self.get_outbound_pending_htlc_stats().pending_htlcs_value_msat as i64
+                               - self.get_outbound_pending_htlc_stats(None).pending_htlcs_value_msat as i64
                                - self.counterparty_selected_channel_reserve_satoshis.unwrap_or(0) as i64 * 1000,
                        0) as u64
                )
        }
 
        pub fn get_holder_counterparty_selected_channel_reserve_satoshis(&self) -> (u64, Option<u64>) {
-               (Self::get_holder_selected_channel_reserve_satoshis(self.channel_value_satoshis),
-               self.counterparty_selected_channel_reserve_satoshis)
+               (self.holder_selected_channel_reserve_satoshis, self.counterparty_selected_channel_reserve_satoshis)
        }
 
-       // Get the fee cost of a commitment tx with a given number of HTLC outputs.
+       // Get the fee cost in MSATS of a commitment tx with a given number of HTLC outputs.
        // Note that num_htlcs should not include dust HTLCs.
-       fn commit_tx_fee_msat(&self, num_htlcs: usize) -> u64 {
+       fn commit_tx_fee_msat(feerate_per_kw: u32, num_htlcs: usize) -> u64 {
                // Note that we need to divide before multiplying to round properly,
                // since the lowest denomination of bitcoin on-chain is the satoshi.
-               (COMMITMENT_TX_BASE_WEIGHT + num_htlcs as u64 * COMMITMENT_TX_WEIGHT_PER_HTLC) * self.feerate_per_kw as u64 / 1000 * 1000
+               (COMMITMENT_TX_BASE_WEIGHT + num_htlcs as u64 * COMMITMENT_TX_WEIGHT_PER_HTLC) * feerate_per_kw as u64 / 1000 * 1000
+       }
+
+       // Get the fee cost in SATS of a commitment tx with a given number of HTLC outputs.
+       // Note that num_htlcs should not include dust HTLCs.
+       #[inline]
+       fn commit_tx_fee_sat(feerate_per_kw: u32, num_htlcs: usize) -> u64 {
+               feerate_per_kw as u64 * (COMMITMENT_TX_BASE_WEIGHT + num_htlcs as u64 * COMMITMENT_TX_WEIGHT_PER_HTLC) / 1000
        }
 
        // Get the commitment tx fee for the local's (i.e. our) next commitment transaction based on the
@@ -2120,12 +2220,12 @@ impl<Signer: Sign> Channel<Signer> {
                }
 
                let num_htlcs = included_htlcs + addl_htlcs;
-               let res = self.commit_tx_fee_msat(num_htlcs);
+               let res = Self::commit_tx_fee_msat(self.feerate_per_kw, num_htlcs);
                #[cfg(any(test, feature = "fuzztarget"))]
                {
                        let mut fee = res;
                        if fee_spike_buffer_htlc.is_some() {
-                               fee = self.commit_tx_fee_msat(num_htlcs - 1);
+                               fee = Self::commit_tx_fee_msat(self.feerate_per_kw, num_htlcs - 1);
                        }
                        let total_pending_htlcs = self.pending_inbound_htlcs.len() + self.pending_outbound_htlcs.len()
                                + self.holding_cell_htlc_updates.len();
@@ -2198,12 +2298,12 @@ impl<Signer: Sign> Channel<Signer> {
                }
 
                let num_htlcs = included_htlcs + addl_htlcs;
-               let res = self.commit_tx_fee_msat(num_htlcs);
+               let res = Self::commit_tx_fee_msat(self.feerate_per_kw, num_htlcs);
                #[cfg(any(test, feature = "fuzztarget"))]
                {
                        let mut fee = res;
                        if fee_spike_buffer_htlc.is_some() {
-                               fee = self.commit_tx_fee_msat(num_htlcs - 1);
+                               fee = Self::commit_tx_fee_msat(self.feerate_per_kw, num_htlcs - 1);
                        }
                        let total_pending_htlcs = self.pending_inbound_htlcs.len() + self.pending_outbound_htlcs.len();
                        let commitment_tx_info = CommitmentTxInfoCached {
@@ -2249,14 +2349,13 @@ impl<Signer: Sign> Channel<Signer> {
                        return Err(ChannelError::Close(format!("Remote side tried to send less than our minimum HTLC value. Lower limit: ({}). Actual: ({})", self.holder_htlc_minimum_msat, msg.amount_msat)));
                }
 
-               let inbound_stats = self.get_inbound_pending_htlc_stats();
-               let outbound_stats = self.get_outbound_pending_htlc_stats();
+               let inbound_stats = self.get_inbound_pending_htlc_stats(None);
+               let outbound_stats = self.get_outbound_pending_htlc_stats(None);
                if inbound_stats.pending_htlcs + 1 > OUR_MAX_HTLCS as u32 {
                        return Err(ChannelError::Close(format!("Remote tried to push more than our max accepted HTLCs ({})", OUR_MAX_HTLCS)));
                }
-               let holder_max_htlc_value_in_flight_msat = Channel::<Signer>::get_holder_max_htlc_value_in_flight_msat(self.channel_value_satoshis);
-               if inbound_stats.pending_htlcs_value_msat + msg.amount_msat > holder_max_htlc_value_in_flight_msat {
-                       return Err(ChannelError::Close(format!("Remote HTLC add would put them over our max HTLC value ({})", holder_max_htlc_value_in_flight_msat)));
+               if inbound_stats.pending_htlcs_value_msat + msg.amount_msat > self.holder_max_htlc_value_in_flight_msat {
+                       return Err(ChannelError::Close(format!("Remote HTLC add would put them over our max HTLC value ({})", self.holder_max_htlc_value_in_flight_msat)));
                }
                // Check holder_selected_channel_reserve_satoshis (we're getting paid, so they have to at least meet
                // the reserve_satoshis we told them to always have as direct payment so that they lose
@@ -2279,7 +2378,7 @@ impl<Signer: Sign> Channel<Signer> {
                        }
                }
 
-               let exposure_dust_limit_timeout_sats = (self.get_dust_buffer_feerate() as u64 * HTLC_TIMEOUT_TX_WEIGHT / 1000) + self.counterparty_dust_limit_satoshis;
+               let exposure_dust_limit_timeout_sats = (self.get_dust_buffer_feerate(None) as u64 * HTLC_TIMEOUT_TX_WEIGHT / 1000) + self.counterparty_dust_limit_satoshis;
                if msg.amount_msat / 1000 < exposure_dust_limit_timeout_sats {
                        let on_counterparty_tx_dust_htlc_exposure_msat = inbound_stats.on_counterparty_tx_dust_exposure_msat + outbound_stats.on_counterparty_tx_dust_exposure_msat + msg.amount_msat;
                        if on_counterparty_tx_dust_htlc_exposure_msat > self.get_max_dust_htlc_exposure_msat() {
@@ -2289,7 +2388,7 @@ impl<Signer: Sign> Channel<Signer> {
                        }
                }
 
-               let exposure_dust_limit_success_sats = (self.get_dust_buffer_feerate() as u64 * HTLC_SUCCESS_TX_WEIGHT / 1000) + self.holder_dust_limit_satoshis;
+               let exposure_dust_limit_success_sats = (self.get_dust_buffer_feerate(None) as u64 * HTLC_SUCCESS_TX_WEIGHT / 1000) + self.holder_dust_limit_satoshis;
                if msg.amount_msat / 1000 < exposure_dust_limit_success_sats {
                        let on_holder_tx_dust_htlc_exposure_msat = inbound_stats.on_holder_tx_dust_exposure_msat + outbound_stats.on_holder_tx_dust_exposure_msat + msg.amount_msat;
                        if on_holder_tx_dust_htlc_exposure_msat > self.get_max_dust_htlc_exposure_msat() {
@@ -2317,9 +2416,7 @@ impl<Signer: Sign> Channel<Signer> {
                        return Err(ChannelError::Close("Remote HTLC add would not leave enough to pay for fees".to_owned()));
                };
 
-               let chan_reserve_msat =
-                       Channel::<Signer>::get_holder_selected_channel_reserve_satoshis(self.channel_value_satoshis) * 1000;
-               if pending_remote_value_msat - msg.amount_msat - remote_commit_tx_fee_msat < chan_reserve_msat {
+               if pending_remote_value_msat - msg.amount_msat - remote_commit_tx_fee_msat < self.holder_selected_channel_reserve_satoshis * 1000 {
                        return Err(ChannelError::Close("Remote HTLC add would put them under remote reserve value".to_owned()));
                }
 
@@ -2334,7 +2431,7 @@ impl<Signer: Sign> Channel<Signer> {
                        // sensitive to fee spikes.
                        let htlc_candidate = HTLCCandidate::new(msg.amount_msat, HTLCInitiator::RemoteOffered);
                        let remote_fee_cost_incl_stuck_buffer_msat = 2 * self.next_remote_commit_tx_fee_msat(htlc_candidate, Some(()));
-                       if pending_remote_value_msat - msg.amount_msat - chan_reserve_msat < remote_fee_cost_incl_stuck_buffer_msat {
+                       if pending_remote_value_msat - msg.amount_msat - self.holder_selected_channel_reserve_satoshis * 1000 < remote_fee_cost_incl_stuck_buffer_msat {
                                // Note that if the pending_forward_status is not updated here, then it's because we're already failing
                                // the HTLC, i.e. its status is already set to failing.
                                log_info!(logger, "Attempting to fail HTLC due to fee spike buffer violation in channel {}. Rebalancing is required.", log_bytes!(self.channel_id()));
@@ -2453,36 +2550,32 @@ impl<Signer: Sign> Channel<Signer> {
 
                let keys = self.build_holder_transaction_keys(self.cur_holder_commitment_transaction_number).map_err(|e| (None, e))?;
 
-               let (num_htlcs, mut htlcs_cloned, commitment_tx, commitment_txid, feerate_per_kw) = {
-                       let commitment_tx = self.build_commitment_transaction(self.cur_holder_commitment_transaction_number, &keys, true, false, logger);
-                       let commitment_txid = {
-                               let trusted_tx = commitment_tx.0.trust();
-                               let bitcoin_tx = trusted_tx.built_transaction();
-                               let sighash = bitcoin_tx.get_sighash_all(&funding_script, self.channel_value_satoshis);
-
-                               log_trace!(logger, "Checking commitment tx signature {} by key {} against tx {} (sighash {}) with redeemscript {} in channel {}",
-                                       log_bytes!(msg.signature.serialize_compact()[..]),
-                                       log_bytes!(self.counterparty_funding_pubkey().serialize()), encode::serialize_hex(&bitcoin_tx.transaction),
-                                       log_bytes!(sighash[..]), encode::serialize_hex(&funding_script), log_bytes!(self.channel_id()));
-                               if let Err(_) = self.secp_ctx.verify(&sighash, &msg.signature, &self.counterparty_funding_pubkey()) {
-                                       return Err((None, ChannelError::Close("Invalid commitment tx signature from peer".to_owned())));
-                               }
-                               bitcoin_tx.txid
-                       };
-                       let htlcs_cloned: Vec<_> = commitment_tx.3.iter().map(|htlc| (htlc.0.clone(), htlc.1.map(|h| h.clone()))).collect();
-                       (commitment_tx.2, htlcs_cloned, commitment_tx.0, commitment_txid, commitment_tx.1)
+               let commitment_stats = self.build_commitment_transaction(self.cur_holder_commitment_transaction_number, &keys, true, false, logger);
+               let commitment_txid = {
+                       let trusted_tx = commitment_stats.tx.trust();
+                       let bitcoin_tx = trusted_tx.built_transaction();
+                       let sighash = bitcoin_tx.get_sighash_all(&funding_script, self.channel_value_satoshis);
+
+                       log_trace!(logger, "Checking commitment tx signature {} by key {} against tx {} (sighash {}) with redeemscript {} in channel {}",
+                               log_bytes!(msg.signature.serialize_compact()[..]),
+                               log_bytes!(self.counterparty_funding_pubkey().serialize()), encode::serialize_hex(&bitcoin_tx.transaction),
+                               log_bytes!(sighash[..]), encode::serialize_hex(&funding_script), log_bytes!(self.channel_id()));
+                       if let Err(_) = self.secp_ctx.verify(&sighash, &msg.signature, &self.counterparty_funding_pubkey()) {
+                               return Err((None, ChannelError::Close("Invalid commitment tx signature from peer".to_owned())));
+                       }
+                       bitcoin_tx.txid
                };
+               let mut htlcs_cloned: Vec<_> = commitment_stats.htlcs_included.iter().map(|htlc| (htlc.0.clone(), htlc.1.map(|h| h.clone()))).collect();
 
                // If our counterparty updated the channel fee in this commitment transaction, check that
                // they can actually afford the new fee now.
                let update_fee = if let Some((_, update_state)) = self.pending_update_fee {
                        update_state == FeeUpdateState::RemoteAnnounced
                } else { false };
-               if update_fee { debug_assert!(!self.is_outbound()); }
-               let total_fee = feerate_per_kw as u64 * (COMMITMENT_TX_BASE_WEIGHT + (num_htlcs as u64) * COMMITMENT_TX_WEIGHT_PER_HTLC) / 1000;
                if update_fee {
-                       let counterparty_reserve_we_require = Channel::<Signer>::get_holder_selected_channel_reserve_satoshis(self.channel_value_satoshis);
-                       if self.channel_value_satoshis - self.value_to_self_msat / 1000 < total_fee + counterparty_reserve_we_require {
+                       debug_assert!(!self.is_outbound());
+                       let counterparty_reserve_we_require_msat = self.holder_selected_channel_reserve_satoshis * 1000;
+                       if commitment_stats.remote_balance_msat < commitment_stats.total_fee_sat * 1000 + counterparty_reserve_we_require_msat {
                                return Err((None, ChannelError::Close("Funding remote cannot afford proposed new fee".to_owned())));
                        }
                }
@@ -2498,25 +2591,25 @@ impl<Signer: Sign> Channel<Signer> {
                                                && info.next_holder_htlc_id == self.next_holder_htlc_id
                                                && info.next_counterparty_htlc_id == self.next_counterparty_htlc_id
                                                && info.feerate == self.feerate_per_kw {
-                                                       assert_eq!(total_fee, info.fee / 1000);
+                                                       assert_eq!(commitment_stats.total_fee_sat, info.fee / 1000);
                                                }
                                }
                        }
                }
 
-               if msg.htlc_signatures.len() != num_htlcs {
-                       return Err((None, ChannelError::Close(format!("Got wrong number of HTLC signatures ({}) from remote. It must be {}", msg.htlc_signatures.len(), num_htlcs))));
+               if msg.htlc_signatures.len() != commitment_stats.num_nondust_htlcs {
+                       return Err((None, ChannelError::Close(format!("Got wrong number of HTLC signatures ({}) from remote. It must be {}", msg.htlc_signatures.len(), commitment_stats.num_nondust_htlcs))));
                }
 
                // TODO: Sadly, we pass HTLCs twice to ChannelMonitor: once via the HolderCommitmentTransaction and once via the update
                let mut htlcs_and_sigs = Vec::with_capacity(htlcs_cloned.len());
                for (idx, (htlc, source)) in htlcs_cloned.drain(..).enumerate() {
                        if let Some(_) = htlc.transaction_output_index {
-                               let htlc_tx = chan_utils::build_htlc_transaction(&commitment_txid, feerate_per_kw,
-                                       self.get_counterparty_selected_contest_delay().unwrap(), &htlc,
+                               let htlc_tx = chan_utils::build_htlc_transaction(&commitment_txid, commitment_stats.feerate_per_kw,
+                                       self.get_counterparty_selected_contest_delay().unwrap(), &htlc, self.opt_anchors(),
                                        &keys.broadcaster_delayed_payment_key, &keys.revocation_key);
 
-                               let htlc_redeemscript = chan_utils::get_htlc_redeemscript(&htlc, &keys);
+                               let htlc_redeemscript = chan_utils::get_htlc_redeemscript(&htlc, self.opt_anchors(), &keys);
                                let htlc_sighash = hash_to_message!(&bip143::SigHashCache::new(&htlc_tx).signature_hash(0, &htlc_redeemscript, htlc.amount_msat / 1000, SigHashType::All)[..]);
                                log_trace!(logger, "Checking HTLC tx signature {} by key {} against tx {} (sighash {}) with redeemscript {} in channel {}.",
                                        log_bytes!(msg.htlc_signatures[idx].serialize_compact()[..]), log_bytes!(keys.countersignatory_htlc_key.serialize()),
@@ -2531,7 +2624,7 @@ impl<Signer: Sign> Channel<Signer> {
                }
 
                let holder_commitment_tx = HolderCommitmentTransaction::new(
-                       commitment_tx,
+                       commitment_stats.tx,
                        msg.signature,
                        msg.htlc_signatures.clone(),
                        &self.get_holder_pubkeys().funding_pubkey,
@@ -2667,7 +2760,7 @@ impl<Signer: Sign> Channel<Signer> {
                                // to rebalance channels.
                                match &htlc_update {
                                        &HTLCUpdateAwaitingACK::AddHTLC {amount_msat, cltv_expiry, ref payment_hash, ref source, ref onion_routing_packet, ..} => {
-                                               match self.send_htlc(amount_msat, *payment_hash, cltv_expiry, source.clone(), onion_routing_packet.clone()) {
+                                               match self.send_htlc(amount_msat, *payment_hash, cltv_expiry, source.clone(), onion_routing_packet.clone(), logger) {
                                                        Ok(update_add_msg_option) => update_add_htlcs.push(update_add_msg_option.unwrap()),
                                                        Err(e) => {
                                                                match e {
@@ -2726,12 +2819,7 @@ impl<Signer: Sign> Channel<Signer> {
                                return Ok((None, htlcs_to_fail));
                        }
                        let update_fee = if let Some(feerate) = self.holding_cell_update_fee.take() {
-                               assert!(self.is_outbound());
-                               self.pending_update_fee = Some((feerate, FeeUpdateState::Outbound));
-                               Some(msgs::UpdateFee {
-                                       channel_id: self.channel_id,
-                                       feerate_per_kw: feerate as u32,
-                               })
+                               self.send_update_fee(feerate, logger)
                        } else {
                                None
                        };
@@ -3028,8 +3116,10 @@ impl<Signer: Sign> Channel<Signer> {
 
        /// Adds a pending update to this channel. See the doc for send_htlc for
        /// further details on the optionness of the return value.
+       /// If our balance is too low to cover the cost of the next commitment transaction at the
+       /// new feerate, the update is cancelled.
        /// You MUST call send_commitment prior to any other calls on this Channel
-       fn send_update_fee(&mut self, feerate_per_kw: u32) -> Option<msgs::UpdateFee> {
+       fn send_update_fee<L: Deref>(&mut self, feerate_per_kw: u32, logger: &L) -> Option<msgs::UpdateFee> where L::Target: Logger {
                if !self.is_outbound() {
                        panic!("Cannot send fee from inbound channel");
                }
@@ -3040,6 +3130,31 @@ impl<Signer: Sign> Channel<Signer> {
                        panic!("Cannot update fee while peer is disconnected/we're awaiting a monitor update (ChannelManager should have caught this)");
                }
 
+               // Before proposing a feerate update, check that we can actually afford the new fee.
+               let inbound_stats = self.get_inbound_pending_htlc_stats(Some(feerate_per_kw));
+               let outbound_stats = self.get_outbound_pending_htlc_stats(Some(feerate_per_kw));
+               let keys = if let Ok(keys) = self.build_holder_transaction_keys(self.cur_holder_commitment_transaction_number) { keys } else { return None; };
+               let commitment_stats = self.build_commitment_transaction(self.cur_holder_commitment_transaction_number, &keys, true, true, logger);
+               let buffer_fee_msat = Channel::<Signer>::commit_tx_fee_sat(feerate_per_kw, commitment_stats.num_nondust_htlcs + outbound_stats.on_holder_tx_holding_cell_htlcs_count as usize + CONCURRENT_INBOUND_HTLC_FEE_BUFFER as usize) * 1000;
+               let holder_balance_msat = commitment_stats.local_balance_msat - outbound_stats.holding_cell_msat;
+               if holder_balance_msat < buffer_fee_msat  + self.counterparty_selected_channel_reserve_satoshis.unwrap() * 1000 {
+                       //TODO: auto-close after a number of failures?
+                       log_debug!(logger, "Cannot afford to send new feerate at {}", feerate_per_kw);
+                       return None;
+               }
+
+               // Note, we evaluate pending htlc "preemptive" trimmed-to-dust threshold at the proposed `feerate_per_kw`.
+               let holder_tx_dust_exposure = inbound_stats.on_holder_tx_dust_exposure_msat + outbound_stats.on_holder_tx_dust_exposure_msat;
+               let counterparty_tx_dust_exposure = inbound_stats.on_counterparty_tx_dust_exposure_msat + outbound_stats.on_counterparty_tx_dust_exposure_msat;
+               if holder_tx_dust_exposure > self.get_max_dust_htlc_exposure_msat() {
+                       log_debug!(logger, "Cannot afford to send new feerate at {} without infringing max dust htlc exposure", feerate_per_kw);
+                       return None;
+               }
+               if counterparty_tx_dust_exposure > self.get_max_dust_htlc_exposure_msat() {
+                       log_debug!(logger, "Cannot afford to send new feerate at {} without infringing max dust htlc exposure", feerate_per_kw);
+                       return None;
+               }
+
                if (self.channel_state & (ChannelState::AwaitingRemoteRevoke as u32 | ChannelState::MonitorUpdateFailed as u32)) != 0 {
                        self.holding_cell_update_fee = Some(feerate_per_kw);
                        return None;
@@ -3055,7 +3170,7 @@ impl<Signer: Sign> Channel<Signer> {
        }
 
        pub fn send_update_fee_and_commit<L: Deref>(&mut self, feerate_per_kw: u32, logger: &L) -> Result<Option<(msgs::UpdateFee, msgs::CommitmentSigned, ChannelMonitorUpdate)>, ChannelError> where L::Target: Logger {
-               match self.send_update_fee(feerate_per_kw) {
+               match self.send_update_fee(feerate_per_kw, logger) {
                        Some(update_fee) => {
                                let (commitment_signed, monitor_update) = self.send_commitment_no_status_check(logger)?;
                                Ok(Some((update_fee, commitment_signed, monitor_update)))
@@ -3219,7 +3334,7 @@ impl<Signer: Sign> Channel<Signer> {
                        return Err(ChannelError::Close("Peer sent update_fee when we needed a channel_reestablish".to_owned()));
                }
                Channel::<Signer>::check_remote_fee(fee_estimator, msg.feerate_per_kw)?;
-               let feerate_over_dust_buffer = msg.feerate_per_kw > self.get_dust_buffer_feerate();
+               let feerate_over_dust_buffer = msg.feerate_per_kw > self.get_dust_buffer_feerate(None);
 
                self.pending_update_fee = Some((msg.feerate_per_kw, FeeUpdateState::RemoteAnnounced));
                self.update_time_counter += 1;
@@ -3227,8 +3342,8 @@ impl<Signer: Sign> Channel<Signer> {
                // `get_dust_buffer_feerate` considers the `pending_update_fee` status), check that we
                // won't be pushed over our dust exposure limit by the feerate increase.
                if feerate_over_dust_buffer {
-                       let inbound_stats = self.get_inbound_pending_htlc_stats();
-                       let outbound_stats = self.get_outbound_pending_htlc_stats();
+                       let inbound_stats = self.get_inbound_pending_htlc_stats(None);
+                       let outbound_stats = self.get_outbound_pending_htlc_stats(None);
                        let holder_tx_dust_exposure = inbound_stats.on_holder_tx_dust_exposure_msat + outbound_stats.on_holder_tx_dust_exposure_msat;
                        let counterparty_tx_dust_exposure = inbound_stats.on_counterparty_tx_dust_exposure_msat + outbound_stats.on_counterparty_tx_dust_exposure_msat;
                        if holder_tx_dust_exposure > self.get_max_dust_htlc_exposure_msat() {
@@ -3900,7 +4015,7 @@ impl<Signer: Sign> Channel<Signer> {
                        // channel might have been used to route very small values (either by honest users or as DoS).
                        self.channel_value_satoshis * 1000 * 9 / 10,
 
-                       Channel::<Signer>::get_holder_max_htlc_value_in_flight_msat(self.channel_value_satoshis)
+                       self.holder_max_htlc_value_in_flight_msat
                );
        }
 
@@ -3929,7 +4044,7 @@ impl<Signer: Sign> Channel<Signer> {
                self.feerate_per_kw
        }
 
-       pub fn get_dust_buffer_feerate(&self) -> u32 {
+       pub fn get_dust_buffer_feerate(&self, outbound_feerate_update: Option<u32>) -> u32 {
                // When calculating our exposure to dust HTLCs, we assume that the channel feerate
                // may, at any point, increase by at least 10 sat/vB (i.e 2530 sat/kWU) or 25%,
                // whichever is higher. This ensures that we aren't suddenly exposed to significantly
@@ -3941,6 +4056,9 @@ impl<Signer: Sign> Channel<Signer> {
                if let Some((feerate, _)) = self.pending_update_fee {
                        feerate_per_kw = cmp::max(feerate_per_kw, feerate);
                }
+               if let Some(feerate) = outbound_feerate_update {
+                       feerate_per_kw = cmp::max(feerate_per_kw, feerate);
+               }
                cmp::max(2530, feerate_per_kw * 1250 / 1000)
        }
 
@@ -4117,7 +4235,7 @@ impl<Signer: Sign> Channel<Signer> {
        /// In the first case, we store the confirmation height and calculating the short channel id.
        /// In the second, we simply return an Err indicating we need to be force-closed now.
        pub fn transactions_confirmed<L: Deref>(&mut self, block_hash: &BlockHash, height: u32, txdata: &TransactionData, logger: &L)
-                       -> Result<Option<msgs::FundingLocked>, msgs::ErrorMessage> where L::Target: Logger {
+       -> Result<Option<msgs::FundingLocked>, ClosureReason> where L::Target: Logger {
                let non_shutdown_state = self.channel_state & (!MULTI_STATE_FLAGS);
                for &(index_in_block, tx) in txdata.iter() {
                        if let Some(funding_txo) = self.get_funding_txo() {
@@ -4138,10 +4256,8 @@ impl<Signer: Sign> Channel<Signer> {
                                                                panic!("Client called ChannelManager::funding_transaction_generated with bogus transaction!");
                                                        }
                                                        self.update_time_counter += 1;
-                                                       return Err(msgs::ErrorMessage {
-                                                               channel_id: self.channel_id(),
-                                                               data: "funding tx had wrong script/value or output index".to_owned()
-                                                       });
+                                                       let err_reason = "funding tx had wrong script/value or output index";
+                                                       return Err(ClosureReason::ProcessingError { err: err_reason.to_owned() });
                                                } else {
                                                        if self.is_outbound() {
                                                                for input in tx.input.iter() {
@@ -4172,10 +4288,7 @@ impl<Signer: Sign> Channel<Signer> {
                                for inp in tx.input.iter() {
                                        if inp.previous_output == funding_txo.into_bitcoin_outpoint() {
                                                log_info!(logger, "Detected channel-closing tx {} spending {}:{}, closing channel {}", tx.txid(), inp.previous_output.txid, inp.previous_output.vout, log_bytes!(self.channel_id()));
-                                               return Err(msgs::ErrorMessage {
-                                                       channel_id: self.channel_id(),
-                                                       data: "Commitment or closing transaction was confirmed on chain.".to_owned()
-                                               });
+                                               return Err(ClosureReason::CommitmentTxConfirmed);
                                        }
                                }
                        }
@@ -4195,9 +4308,12 @@ impl<Signer: Sign> Channel<Signer> {
        /// May return some HTLCs (and their payment_hash) which have timed out and should be failed
        /// back.
        pub fn best_block_updated<L: Deref>(&mut self, height: u32, highest_header_time: u32, logger: &L)
-                       -> Result<(Option<msgs::FundingLocked>, Vec<(HTLCSource, PaymentHash)>), msgs::ErrorMessage> where L::Target: Logger {
+       -> Result<(Option<msgs::FundingLocked>, Vec<(HTLCSource, PaymentHash)>), ClosureReason> where L::Target: Logger {
                let mut timed_out_htlcs = Vec::new();
-               let unforwarded_htlc_cltv_limit = height + HTLC_FAIL_BACK_BUFFER;
+               // This mirrors the check in ChannelManager::decode_update_add_htlc_onion, refusing to
+               // forward an HTLC when our counterparty should almost certainly just fail it for expiring
+               // ~now.
+               let unforwarded_htlc_cltv_limit = height + LATENCY_GRACE_PERIOD_BLOCKS;
                self.holding_cell_htlc_updates.retain(|htlc_update| {
                        match htlc_update {
                                &HTLCUpdateAwaitingACK::AddHTLC { ref payment_hash, ref source, ref cltv_expiry, .. } => {
@@ -4233,11 +4349,17 @@ impl<Signer: Sign> Channel<Signer> {
                        // close the channel and hope we can get the latest state on chain (because presumably
                        // the funding transaction is at least still in the mempool of most nodes).
                        if funding_tx_confirmations < self.minimum_depth.unwrap() as i64 / 2 {
-                               return Err(msgs::ErrorMessage {
-                                       channel_id: self.channel_id(),
-                                       data: format!("Funding transaction was un-confirmed. Locked at {} confs, now have {} confs.", self.minimum_depth.unwrap(), funding_tx_confirmations),
-                               });
+                               let err_reason = format!("Funding transaction was un-confirmed. Locked at {} confs, now have {} confs.",
+                                       self.minimum_depth.unwrap(), funding_tx_confirmations);
+                               return Err(ClosureReason::ProcessingError { err: err_reason });
                        }
+               } else if !self.is_outbound() && self.funding_tx_confirmed_in.is_none() &&
+                               height >= self.channel_creation_height + FUNDING_CONF_DEADLINE_BLOCKS {
+                       log_info!(logger, "Closing channel {} due to funding timeout", log_bytes!(self.channel_id));
+                       // If funding_tx_confirmed_in is unset, the channel must not be active
+                       assert!(non_shutdown_state <= ChannelState::ChannelFunded as u32);
+                       assert_eq!(non_shutdown_state & ChannelState::OurFundingLocked as u32, 0);
+                       return Err(ClosureReason::FundingTimedOut);
                }
 
                Ok((None, timed_out_htlcs))
@@ -4246,7 +4368,7 @@ impl<Signer: Sign> Channel<Signer> {
        /// Indicates the funding transaction is no longer confirmed in the main chain. This may
        /// force-close the channel, but may also indicate a harmless reorganization of a block or two
        /// before the channel has reached funding_locked and we can just wait for more blocks.
-       pub fn funding_transaction_unconfirmed<L: Deref>(&mut self, logger: &L) -> Result<(), msgs::ErrorMessage> where L::Target: Logger {
+       pub fn funding_transaction_unconfirmed<L: Deref>(&mut self, logger: &L) -> Result<(), ClosureReason> where L::Target: Logger {
                if self.funding_tx_confirmation_height != 0 {
                        // We handle the funding disconnection by calling best_block_updated with a height one
                        // below where our funding was connected, implying a reorg back to conf_height - 1.
@@ -4293,8 +4415,8 @@ impl<Signer: Sign> Channel<Signer> {
                        funding_satoshis: self.channel_value_satoshis,
                        push_msat: self.channel_value_satoshis * 1000 - self.value_to_self_msat,
                        dust_limit_satoshis: self.holder_dust_limit_satoshis,
-                       max_htlc_value_in_flight_msat: Channel::<Signer>::get_holder_max_htlc_value_in_flight_msat(self.channel_value_satoshis),
-                       channel_reserve_satoshis: Channel::<Signer>::get_holder_selected_channel_reserve_satoshis(self.channel_value_satoshis),
+                       max_htlc_value_in_flight_msat: self.holder_max_htlc_value_in_flight_msat,
+                       channel_reserve_satoshis: self.holder_selected_channel_reserve_satoshis,
                        htlc_minimum_msat: self.holder_htlc_minimum_msat,
                        feerate_per_kw: self.feerate_per_kw as u32,
                        to_self_delay: self.get_holder_selected_contest_delay(),
@@ -4331,8 +4453,8 @@ impl<Signer: Sign> Channel<Signer> {
                msgs::AcceptChannel {
                        temporary_channel_id: self.channel_id,
                        dust_limit_satoshis: self.holder_dust_limit_satoshis,
-                       max_htlc_value_in_flight_msat: Channel::<Signer>::get_holder_max_htlc_value_in_flight_msat(self.channel_value_satoshis),
-                       channel_reserve_satoshis: Channel::<Signer>::get_holder_selected_channel_reserve_satoshis(self.channel_value_satoshis),
+                       max_htlc_value_in_flight_msat: self.holder_max_htlc_value_in_flight_msat,
+                       channel_reserve_satoshis: self.holder_selected_channel_reserve_satoshis,
                        htlc_minimum_msat: self.holder_htlc_minimum_msat,
                        minimum_depth: self.minimum_depth.unwrap(),
                        to_self_delay: self.get_holder_selected_contest_delay(),
@@ -4353,7 +4475,7 @@ impl<Signer: Sign> Channel<Signer> {
        /// If an Err is returned, it is a ChannelError::Close (for get_outbound_funding_created)
        fn get_outbound_funding_created_signature<L: Deref>(&mut self, logger: &L) -> Result<Signature, ChannelError> where L::Target: Logger {
                let counterparty_keys = self.build_remote_transaction_keys()?;
-               let counterparty_initial_commitment_tx = self.build_commitment_transaction(self.cur_counterparty_commitment_transaction_number, &counterparty_keys, false, false, logger).0;
+               let counterparty_initial_commitment_tx = self.build_commitment_transaction(self.cur_counterparty_commitment_transaction_number, &counterparty_keys, false, false, logger).tx;
                Ok(self.holder_signer.sign_counterparty_commitment(&counterparty_initial_commitment_tx, &self.secp_ctx)
                                .map_err(|_| ChannelError::Close("Failed to get signatures for new commitment_signed".to_owned()))?.0)
        }
@@ -4572,7 +4694,7 @@ impl<Signer: Sign> Channel<Signer> {
        /// You MUST call send_commitment prior to calling any other methods on this Channel!
        ///
        /// If an Err is returned, it's a ChannelError::Ignore!
-       pub fn send_htlc(&mut self, amount_msat: u64, payment_hash: PaymentHash, cltv_expiry: u32, source: HTLCSource, onion_routing_packet: msgs::OnionPacket) -> Result<Option<msgs::UpdateAddHTLC>, ChannelError> {
+       pub fn send_htlc<L: Deref>(&mut self, amount_msat: u64, payment_hash: PaymentHash, cltv_expiry: u32, source: HTLCSource, onion_routing_packet: msgs::OnionPacket, logger: &L) -> Result<Option<msgs::UpdateAddHTLC>, ChannelError> where L::Target: Logger {
                if (self.channel_state & (ChannelState::ChannelFunded as u32 | BOTH_SIDES_SHUTDOWN_MASK)) != (ChannelState::ChannelFunded as u32) {
                        return Err(ChannelError::Ignore("Cannot send HTLC until channel is fully established and we haven't started shutting down".to_owned()));
                }
@@ -4599,8 +4721,8 @@ impl<Signer: Sign> Channel<Signer> {
                        return Err(ChannelError::Ignore("Cannot send an HTLC while disconnected from channel counterparty".to_owned()));
                }
 
-               let inbound_stats = self.get_inbound_pending_htlc_stats();
-               let outbound_stats = self.get_outbound_pending_htlc_stats();
+               let inbound_stats = self.get_inbound_pending_htlc_stats(None);
+               let outbound_stats = self.get_outbound_pending_htlc_stats(None);
                if outbound_stats.pending_htlcs + 1 > self.counterparty_max_accepted_htlcs as u32 {
                        return Err(ChannelError::Ignore(format!("Cannot push more than their max accepted HTLCs ({})", self.counterparty_max_accepted_htlcs)));
                }
@@ -4609,18 +4731,19 @@ impl<Signer: Sign> Channel<Signer> {
                        return Err(ChannelError::Ignore(format!("Cannot send value that would put us over the max HTLC value in flight our peer will accept ({})", self.counterparty_max_htlc_value_in_flight_msat)));
                }
 
+               let keys = self.build_holder_transaction_keys(self.cur_holder_commitment_transaction_number)?;
+               let commitment_stats = self.build_commitment_transaction(self.cur_holder_commitment_transaction_number, &keys, true, true, logger);
                if !self.is_outbound() {
                        // Check that we won't violate the remote channel reserve by adding this HTLC.
-                       let counterparty_balance_msat = self.channel_value_satoshis * 1000 - self.value_to_self_msat;
-                       let holder_selected_chan_reserve_msat = Channel::<Signer>::get_holder_selected_channel_reserve_satoshis(self.channel_value_satoshis) * 1000;
                        let htlc_candidate = HTLCCandidate::new(amount_msat, HTLCInitiator::LocalOffered);
                        let counterparty_commit_tx_fee_msat = self.next_remote_commit_tx_fee_msat(htlc_candidate, None);
-                       if counterparty_balance_msat < holder_selected_chan_reserve_msat + counterparty_commit_tx_fee_msat {
+                       let holder_selected_chan_reserve_msat = self.holder_selected_channel_reserve_satoshis * 1000;
+                       if commitment_stats.remote_balance_msat < counterparty_commit_tx_fee_msat + holder_selected_chan_reserve_msat {
                                return Err(ChannelError::Ignore("Cannot send value that would put counterparty balance under holder-announced channel reserve value".to_owned()));
                        }
                }
 
-               let exposure_dust_limit_success_sats = (self.get_dust_buffer_feerate() as u64 * HTLC_SUCCESS_TX_WEIGHT / 1000) + self.counterparty_dust_limit_satoshis;
+               let exposure_dust_limit_success_sats = (self.get_dust_buffer_feerate(None) as u64 * HTLC_SUCCESS_TX_WEIGHT / 1000) + self.counterparty_dust_limit_satoshis;
                if amount_msat / 1000 < exposure_dust_limit_success_sats {
                        let on_counterparty_dust_htlc_exposure_msat = inbound_stats.on_counterparty_tx_dust_exposure_msat + outbound_stats.on_counterparty_tx_dust_exposure_msat + amount_msat;
                        if on_counterparty_dust_htlc_exposure_msat > self.get_max_dust_htlc_exposure_msat() {
@@ -4629,7 +4752,7 @@ impl<Signer: Sign> Channel<Signer> {
                        }
                }
 
-               let exposure_dust_limit_timeout_sats = (self.get_dust_buffer_feerate() as u64 * HTLC_TIMEOUT_TX_WEIGHT / 1000) + self.holder_dust_limit_satoshis;
+               let exposure_dust_limit_timeout_sats = (self.get_dust_buffer_feerate(None) as u64 * HTLC_TIMEOUT_TX_WEIGHT / 1000) + self.holder_dust_limit_satoshis;
                if amount_msat / 1000 <  exposure_dust_limit_timeout_sats {
                        let on_holder_dust_htlc_exposure_msat = inbound_stats.on_holder_tx_dust_exposure_msat + outbound_stats.on_holder_tx_dust_exposure_msat + amount_msat;
                        if on_holder_dust_htlc_exposure_msat > self.get_max_dust_htlc_exposure_msat() {
@@ -4638,9 +4761,9 @@ impl<Signer: Sign> Channel<Signer> {
                        }
                }
 
-               let pending_value_to_self_msat = self.value_to_self_msat - outbound_stats.pending_htlcs_value_msat;
-               if pending_value_to_self_msat < amount_msat {
-                       return Err(ChannelError::Ignore(format!("Cannot send value that would overdraw remaining funds. Amount: {}, pending value to self {}", amount_msat, pending_value_to_self_msat)));
+               let holder_balance_msat = commitment_stats.local_balance_msat - outbound_stats.holding_cell_msat;
+               if holder_balance_msat < amount_msat {
+                       return Err(ChannelError::Ignore(format!("Cannot send value that would overdraw remaining funds. Amount: {}, pending value to self {}", amount_msat, holder_balance_msat)));
                }
 
                // `2 *` and extra HTLC are for the fee spike buffer.
@@ -4648,14 +4771,14 @@ impl<Signer: Sign> Channel<Signer> {
                        let htlc_candidate = HTLCCandidate::new(amount_msat, HTLCInitiator::LocalOffered);
                        FEE_SPIKE_BUFFER_FEE_INCREASE_MULTIPLE * self.next_local_commit_tx_fee_msat(htlc_candidate, Some(()))
                } else { 0 };
-               if pending_value_to_self_msat - amount_msat < commit_tx_fee_msat {
-                       return Err(ChannelError::Ignore(format!("Cannot send value that would not leave enough to pay for fees. Pending value to self: {}. local_commit_tx_fee {}", pending_value_to_self_msat, commit_tx_fee_msat)));
+               if holder_balance_msat - amount_msat < commit_tx_fee_msat {
+                       return Err(ChannelError::Ignore(format!("Cannot send value that would not leave enough to pay for fees. Pending value to self: {}. local_commit_tx_fee {}", holder_balance_msat, commit_tx_fee_msat)));
                }
 
                // Check self.counterparty_selected_channel_reserve_satoshis (the amount we must keep as
                // reserve for the remote to have something to claim if we misbehave)
                let chan_reserve_msat = self.counterparty_selected_channel_reserve_satoshis.unwrap() * 1000;
-               if pending_value_to_self_msat - amount_msat - commit_tx_fee_msat < chan_reserve_msat {
+               if holder_balance_msat - amount_msat - commit_tx_fee_msat < chan_reserve_msat {
                        return Err(ChannelError::Ignore(format!("Cannot send value that would put our balance under counterparty-announced channel reserve value ({})", chan_reserve_msat)));
                }
 
@@ -4789,9 +4912,8 @@ impl<Signer: Sign> Channel<Signer> {
        /// when we shouldn't change HTLC/channel state.
        fn send_commitment_no_state_update<L: Deref>(&self, logger: &L) -> Result<(msgs::CommitmentSigned, (Txid, Vec<(HTLCOutputInCommitment, Option<&HTLCSource>)>)), ChannelError> where L::Target: Logger {
                let counterparty_keys = self.build_remote_transaction_keys()?;
-               let counterparty_commitment_tx = self.build_commitment_transaction(self.cur_counterparty_commitment_transaction_number, &counterparty_keys, false, true, logger);
-               let feerate_per_kw = counterparty_commitment_tx.1;
-               let counterparty_commitment_txid = counterparty_commitment_tx.0.trust().txid();
+               let commitment_stats = self.build_commitment_transaction(self.cur_counterparty_commitment_transaction_number, &counterparty_keys, false, true, logger);
+               let counterparty_commitment_txid = commitment_stats.tx.trust().txid();
                let (signature, htlc_signatures);
 
                #[cfg(any(test, feature = "fuzztarget"))]
@@ -4805,7 +4927,7 @@ impl<Signer: Sign> Channel<Signer> {
                                                && info.next_holder_htlc_id == self.next_holder_htlc_id
                                                && info.next_counterparty_htlc_id == self.next_counterparty_htlc_id
                                                && info.feerate == self.feerate_per_kw {
-                                                       let actual_fee = self.commit_tx_fee_msat(counterparty_commitment_tx.2);
+                                                       let actual_fee = Self::commit_tx_fee_msat(self.feerate_per_kw, commitment_stats.num_nondust_htlcs);
                                                        assert_eq!(actual_fee, info.fee);
                                                }
                                }
@@ -4813,25 +4935,25 @@ impl<Signer: Sign> Channel<Signer> {
                }
 
                {
-                       let mut htlcs = Vec::with_capacity(counterparty_commitment_tx.3.len());
-                       for &(ref htlc, _) in counterparty_commitment_tx.3.iter() {
+                       let mut htlcs = Vec::with_capacity(commitment_stats.htlcs_included.len());
+                       for &(ref htlc, _) in commitment_stats.htlcs_included.iter() {
                                htlcs.push(htlc);
                        }
 
-                       let res = self.holder_signer.sign_counterparty_commitment(&counterparty_commitment_tx.0, &self.secp_ctx)
+                       let res = self.holder_signer.sign_counterparty_commitment(&commitment_stats.tx, &self.secp_ctx)
                                .map_err(|_| ChannelError::Close("Failed to get signatures for new commitment_signed".to_owned()))?;
                        signature = res.0;
                        htlc_signatures = res.1;
 
                        log_trace!(logger, "Signed remote commitment tx {} (txid {}) with redeemscript {} -> {} in channel {}",
-                               encode::serialize_hex(&counterparty_commitment_tx.0.trust().built_transaction().transaction),
+                               encode::serialize_hex(&commitment_stats.tx.trust().built_transaction().transaction),
                                &counterparty_commitment_txid, encode::serialize_hex(&self.get_funding_redeemscript()),
                                log_bytes!(signature.serialize_compact()[..]), log_bytes!(self.channel_id()));
 
                        for (ref htlc_sig, ref htlc) in htlc_signatures.iter().zip(htlcs) {
                                log_trace!(logger, "Signed remote HTLC tx {} with redeemscript {} with pubkey {} -> {} in channel {}",
-                                       encode::serialize_hex(&chan_utils::build_htlc_transaction(&counterparty_commitment_txid, feerate_per_kw, self.get_holder_selected_contest_delay(), htlc, &counterparty_keys.broadcaster_delayed_payment_key, &counterparty_keys.revocation_key)),
-                                       encode::serialize_hex(&chan_utils::get_htlc_redeemscript(&htlc, &counterparty_keys)),
+                                       encode::serialize_hex(&chan_utils::build_htlc_transaction(&counterparty_commitment_txid, commitment_stats.feerate_per_kw, self.get_holder_selected_contest_delay(), htlc, self.opt_anchors(), &counterparty_keys.broadcaster_delayed_payment_key, &counterparty_keys.revocation_key)),
+                                       encode::serialize_hex(&chan_utils::get_htlc_redeemscript(&htlc, self.opt_anchors(), &counterparty_keys)),
                                        log_bytes!(counterparty_keys.broadcaster_htlc_key.serialize()),
                                        log_bytes!(htlc_sig.serialize_compact()[..]), log_bytes!(self.channel_id()));
                        }
@@ -4841,7 +4963,7 @@ impl<Signer: Sign> Channel<Signer> {
                        channel_id: self.channel_id,
                        signature,
                        htlc_signatures,
-               }, (counterparty_commitment_txid, counterparty_commitment_tx.3)))
+               }, (counterparty_commitment_txid, commitment_stats.htlcs_included)))
        }
 
        /// Adds a pending outbound HTLC to this channel, and creates a signed commitment transaction
@@ -4849,7 +4971,7 @@ impl<Signer: Sign> Channel<Signer> {
        /// Shorthand for calling send_htlc() followed by send_commitment(), see docs on those for
        /// more info.
        pub fn send_htlc_and_commit<L: Deref>(&mut self, amount_msat: u64, payment_hash: PaymentHash, cltv_expiry: u32, source: HTLCSource, onion_routing_packet: msgs::OnionPacket, logger: &L) -> Result<Option<(msgs::UpdateAddHTLC, msgs::CommitmentSigned, ChannelMonitorUpdate)>, ChannelError> where L::Target: Logger {
-               match self.send_htlc(amount_msat, payment_hash, cltv_expiry, source, onion_routing_packet)? {
+               match self.send_htlc(amount_msat, payment_hash, cltv_expiry, source, onion_routing_packet, logger)? {
                        Some(update_add_htlc) => {
                                let (commitment_signed, monitor_update) = self.send_commitment_no_status_check(logger)?;
                                Ok(Some((update_add_htlc, commitment_signed, monitor_update)))
@@ -5254,6 +5376,22 @@ impl<Signer: Sign> Writeable for Channel<Signer> {
                        htlc.write(writer)?;
                }
 
+               // If the channel type is something other than only-static-remote-key, then we need to have
+               // older clients fail to deserialize this channel at all. If the type is
+               // only-static-remote-key, we simply consider it "default" and don't write the channel type
+               // out at all.
+               let chan_type = if self.channel_type != ChannelTypeFeatures::only_static_remote_key() {
+                       Some(&self.channel_type) } else { None };
+
+               // The same logic applies for `holder_selected_channel_reserve_satoshis` and
+               // `holder_max_htlc_value_in_flight_msat` values other than the defaults.
+               let serialized_holder_selected_reserve =
+                       if self.holder_selected_channel_reserve_satoshis != Self::get_holder_selected_channel_reserve_satoshis(self.channel_value_satoshis)
+                       { Some(self.holder_selected_channel_reserve_satoshis) } else { None };
+               let serialized_holder_htlc_max_in_flight =
+                       if self.holder_max_htlc_value_in_flight_msat != Self::get_holder_max_htlc_value_in_flight_msat(self.channel_value_satoshis)
+                       { Some(self.holder_max_htlc_value_in_flight_msat) } else { None };
+
                write_tlv_fields!(writer, {
                        (0, self.announcement_sigs, option),
                        // minimum_depth and counterparty_selected_channel_reserve_satoshis used to have a
@@ -5263,12 +5401,15 @@ impl<Signer: Sign> Writeable for Channel<Signer> {
                        // and new versions map the default values to None and allow the TLV entries here to
                        // override that.
                        (1, self.minimum_depth, option),
+                       (2, chan_type, option),
                        (3, self.counterparty_selected_channel_reserve_satoshis, option),
+                       (4, serialized_holder_selected_reserve, option),
                        (5, self.config, required),
+                       (6, serialized_holder_htlc_max_in_flight, option),
                        (7, self.shutdown_scriptpubkey, option),
                        (9, self.target_closing_feerate_sats_per_kw, option),
                        (11, self.monitor_pending_finalized_fulfills, vec_type),
-                       (13, self.channel_type, required),
+                       (13, self.channel_creation_height, required),
                });
 
                Ok(())
@@ -5276,9 +5417,10 @@ impl<Signer: Sign> Writeable for Channel<Signer> {
 }
 
 const MAX_ALLOC_SIZE: usize = 64*1024;
-impl<'a, Signer: Sign, K: Deref> ReadableArgs<&'a K> for Channel<Signer>
+impl<'a, Signer: Sign, K: Deref> ReadableArgs<(&'a K, u32)> for Channel<Signer>
                where K::Target: KeysInterface<Signer = Signer> {
-       fn read<R : io::Read>(reader: &mut R, keys_source: &'a K) -> Result<Self, DecodeError> {
+       fn read<R : io::Read>(reader: &mut R, args: (&'a K, u32)) -> Result<Self, DecodeError> {
+               let (keys_source, serialized_height) = args;
                let ver = read_ver_prefix!(reader, SERIALIZATION_VERSION);
 
                let user_id = Readable::read(reader)?;
@@ -5503,18 +5645,24 @@ impl<'a, Signer: Sign, K: Deref> ReadableArgs<&'a K> for Channel<Signer>
                let mut announcement_sigs = None;
                let mut target_closing_feerate_sats_per_kw = None;
                let mut monitor_pending_finalized_fulfills = Some(Vec::new());
+               let mut holder_selected_channel_reserve_satoshis = Some(Self::get_holder_selected_channel_reserve_satoshis(channel_value_satoshis));
+               let mut holder_max_htlc_value_in_flight_msat = Some(Self::get_holder_max_htlc_value_in_flight_msat(channel_value_satoshis));
                // Prior to supporting channel type negotiation, all of our channels were static_remotekey
                // only, so we default to that if none was written.
                let mut channel_type = Some(ChannelTypeFeatures::only_static_remote_key());
+               let mut channel_creation_height = Some(serialized_height);
                read_tlv_fields!(reader, {
                        (0, announcement_sigs, option),
                        (1, minimum_depth, option),
+                       (2, channel_type, option),
                        (3, counterparty_selected_channel_reserve_satoshis, option),
+                       (4, holder_selected_channel_reserve_satoshis, option),
                        (5, config, option), // Note that if none is provided we will *not* overwrite the existing one.
+                       (6, holder_max_htlc_value_in_flight_msat, option),
                        (7, shutdown_scriptpubkey, option),
                        (9, target_closing_feerate_sats_per_kw, option),
                        (11, monitor_pending_finalized_fulfills, vec_type),
-                       (13, channel_type, option),
+                       (13, channel_creation_height, option),
                });
 
                let chan_features = channel_type.as_ref().unwrap();
@@ -5524,6 +5672,11 @@ impl<'a, Signer: Sign, K: Deref> ReadableArgs<&'a K> for Channel<Signer>
                        return Err(DecodeError::UnknownRequiredFeature);
                }
 
+               if channel_parameters.opt_anchors.is_some() {
+                       // Relax this check when ChannelTypeFeatures supports anchors.
+                       return Err(DecodeError::InvalidValue);
+               }
+
                let mut secp_ctx = Secp256k1::new();
                secp_ctx.seeded_randomize(&keys_source.get_secure_random_bytes());
 
@@ -5579,11 +5732,14 @@ impl<'a, Signer: Sign, K: Deref> ReadableArgs<&'a K> for Channel<Signer>
                        funding_tx_confirmed_in,
                        funding_tx_confirmation_height,
                        short_channel_id,
+                       channel_creation_height: channel_creation_height.unwrap(),
 
                        counterparty_dust_limit_satoshis,
                        holder_dust_limit_satoshis,
                        counterparty_max_htlc_value_in_flight_msat,
+                       holder_max_htlc_value_in_flight_msat: holder_max_htlc_value_in_flight_msat.unwrap(),
                        counterparty_selected_channel_reserve_satoshis,
+                       holder_selected_channel_reserve_satoshis: holder_selected_channel_reserve_satoshis.unwrap(),
                        counterparty_htlc_minimum_msat,
                        holder_htlc_minimum_msat,
                        counterparty_max_accepted_htlcs,
@@ -5727,7 +5883,7 @@ mod tests {
                let secp_ctx = Secp256k1::new();
                let node_id = PublicKey::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[42; 32]).unwrap());
                let config = UserConfig::default();
-               match Channel::<EnforcingSigner>::new_outbound(&&fee_estimator, &&keys_provider, node_id, &features, 10000000, 100000, 42, &config) {
+               match Channel::<EnforcingSigner>::new_outbound(&&fee_estimator, &&keys_provider, node_id, &features, 10000000, 100000, 42, &config, 0) {
                        Err(APIError::IncompatibleShutdownScript { script }) => {
                                assert_eq!(script.into_inner(), non_v0_segwit_shutdown_script.into_inner());
                        },
@@ -5749,7 +5905,7 @@ mod tests {
 
                let node_a_node_id = PublicKey::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[42; 32]).unwrap());
                let config = UserConfig::default();
-               let node_a_chan = Channel::<EnforcingSigner>::new_outbound(&&fee_est, &&keys_provider, node_a_node_id, &InitFeatures::known(), 10000000, 100000, 42, &config).unwrap();
+               let node_a_chan = Channel::<EnforcingSigner>::new_outbound(&&fee_est, &&keys_provider, node_a_node_id, &InitFeatures::known(), 10000000, 100000, 42, &config, 0).unwrap();
 
                // Now change the fee so we can check that the fee in the open_channel message is the
                // same as the old fee.
@@ -5767,6 +5923,7 @@ mod tests {
                let seed = [42; 32];
                let network = Network::Testnet;
                let keys_provider = test_utils::TestKeysInterface::new(&seed, network);
+               let logger = test_utils::TestLogger::new();
 
                // Go through the flow of opening a channel between two nodes, making sure
                // they have different dust limits.
@@ -5774,13 +5931,13 @@ mod tests {
                // Create Node A's channel pointing to Node B's pubkey
                let node_b_node_id = PublicKey::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[42; 32]).unwrap());
                let config = UserConfig::default();
-               let mut node_a_chan = Channel::<EnforcingSigner>::new_outbound(&&feeest, &&keys_provider, node_b_node_id, &InitFeatures::known(), 10000000, 100000, 42, &config).unwrap();
+               let mut node_a_chan = Channel::<EnforcingSigner>::new_outbound(&&feeest, &&keys_provider, node_b_node_id, &InitFeatures::known(), 10000000, 100000, 42, &config, 0).unwrap();
 
                // Create Node B's channel by receiving Node A's open_channel message
                // Make sure A's dust limit is as we expect.
                let open_channel_msg = node_a_chan.get_open_channel(genesis_block(network).header.block_hash());
                let node_b_node_id = PublicKey::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[7; 32]).unwrap());
-               let node_b_chan = Channel::<EnforcingSigner>::new_from_req(&&feeest, &&keys_provider, node_b_node_id, &InitFeatures::known(), &open_channel_msg, 7, &config).unwrap();
+               let node_b_chan = Channel::<EnforcingSigner>::new_from_req(&&feeest, &&keys_provider, node_b_node_id, &InitFeatures::known(), &open_channel_msg, 7, &config, 0, &&logger).unwrap();
 
                // Node B --> Node A: accept channel, explicitly setting B's dust limit.
                let mut accept_channel_msg = node_b_chan.get_accept_channel();
@@ -5818,13 +5975,13 @@ mod tests {
                // the dust limit check.
                let htlc_candidate = HTLCCandidate::new(htlc_amount_msat, HTLCInitiator::LocalOffered);
                let local_commit_tx_fee = node_a_chan.next_local_commit_tx_fee_msat(htlc_candidate, None);
-               let local_commit_fee_0_htlcs = node_a_chan.commit_tx_fee_msat(0);
+               let local_commit_fee_0_htlcs = Channel::<EnforcingSigner>::commit_tx_fee_msat(node_a_chan.feerate_per_kw, 0);
                assert_eq!(local_commit_tx_fee, local_commit_fee_0_htlcs);
 
                // Finally, make sure that when Node A calculates the remote's commitment transaction fees, all
                // of the HTLCs are seen to be above the dust limit.
                node_a_chan.channel_transaction_parameters.is_outbound_from_holder = false;
-               let remote_commit_fee_3_htlcs = node_a_chan.commit_tx_fee_msat(3);
+               let remote_commit_fee_3_htlcs = Channel::<EnforcingSigner>::commit_tx_fee_msat(node_a_chan.feerate_per_kw, 3);
                let htlc_candidate = HTLCCandidate::new(htlc_amount_msat, HTLCInitiator::LocalOffered);
                let remote_commit_tx_fee = node_a_chan.next_remote_commit_tx_fee_msat(htlc_candidate, None);
                assert_eq!(remote_commit_tx_fee, remote_commit_fee_3_htlcs);
@@ -5844,10 +6001,10 @@ mod tests {
 
                let node_id = PublicKey::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[42; 32]).unwrap());
                let config = UserConfig::default();
-               let mut chan = Channel::<EnforcingSigner>::new_outbound(&&fee_est, &&keys_provider, node_id, &InitFeatures::known(), 10000000, 100000, 42, &config).unwrap();
+               let mut chan = Channel::<EnforcingSigner>::new_outbound(&&fee_est, &&keys_provider, node_id, &InitFeatures::known(), 10000000, 100000, 42, &config, 0).unwrap();
 
-               let commitment_tx_fee_0_htlcs = chan.commit_tx_fee_msat(0);
-               let commitment_tx_fee_1_htlc = chan.commit_tx_fee_msat(1);
+               let commitment_tx_fee_0_htlcs = Channel::<EnforcingSigner>::commit_tx_fee_msat(chan.feerate_per_kw, 0);
+               let commitment_tx_fee_1_htlc = Channel::<EnforcingSigner>::commit_tx_fee_msat(chan.feerate_per_kw, 1);
 
                // If HTLC_SUCCESS_TX_WEIGHT and HTLC_TIMEOUT_TX_WEIGHT were swapped: then this HTLC would be
                // counted as dust when it shouldn't be.
@@ -5893,12 +6050,12 @@ mod tests {
                // Create Node A's channel pointing to Node B's pubkey
                let node_b_node_id = PublicKey::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[42; 32]).unwrap());
                let config = UserConfig::default();
-               let mut node_a_chan = Channel::<EnforcingSigner>::new_outbound(&&feeest, &&keys_provider, node_b_node_id, &InitFeatures::known(), 10000000, 100000, 42, &config).unwrap();
+               let mut node_a_chan = Channel::<EnforcingSigner>::new_outbound(&&feeest, &&keys_provider, node_b_node_id, &InitFeatures::known(), 10000000, 100000, 42, &config, 0).unwrap();
 
                // Create Node B's channel by receiving Node A's open_channel message
                let open_channel_msg = node_a_chan.get_open_channel(chain_hash);
                let node_b_node_id = PublicKey::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[7; 32]).unwrap());
-               let mut node_b_chan = Channel::<EnforcingSigner>::new_from_req(&&feeest, &&keys_provider, node_b_node_id, &InitFeatures::known(), &open_channel_msg, 7, &config).unwrap();
+               let mut node_b_chan = Channel::<EnforcingSigner>::new_from_req(&&feeest, &&keys_provider, node_b_node_id, &InitFeatures::known(), &open_channel_msg, 7, &config, 0, &&logger).unwrap();
 
                // Node B --> Node A: accept channel
                let accept_channel_msg = node_b_chan.get_accept_channel();
@@ -5955,7 +6112,7 @@ mod tests {
                // Create a channel.
                let node_b_node_id = PublicKey::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[42; 32]).unwrap());
                let config = UserConfig::default();
-               let mut node_a_chan = Channel::<EnforcingSigner>::new_outbound(&&feeest, &&keys_provider, node_b_node_id, &InitFeatures::known(), 10000000, 100000, 42, &config).unwrap();
+               let mut node_a_chan = Channel::<EnforcingSigner>::new_outbound(&&feeest, &&keys_provider, node_b_node_id, &InitFeatures::known(), 10000000, 100000, 42, &config, 0).unwrap();
                assert!(node_a_chan.counterparty_forwarding_info.is_none());
                assert_eq!(node_a_chan.holder_htlc_minimum_msat, 1); // the default
                assert!(node_a_chan.counterparty_forwarding_info().is_none());
@@ -6019,7 +6176,7 @@ mod tests {
                let counterparty_node_id = PublicKey::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[42; 32]).unwrap());
                let mut config = UserConfig::default();
                config.channel_options.announced_channel = false;
-               let mut chan = Channel::<InMemorySigner>::new_outbound(&&feeest, &&keys_provider, counterparty_node_id, &InitFeatures::known(), 10_000_000, 100000, 42, &config).unwrap(); // Nothing uses their network key in this test
+               let mut chan = Channel::<InMemorySigner>::new_outbound(&&feeest, &&keys_provider, counterparty_node_id, &InitFeatures::known(), 10_000_000, 100000, 42, &config, 0).unwrap(); // Nothing uses their network key in this test
                chan.holder_dust_limit_satoshis = 546;
                chan.counterparty_selected_channel_reserve_satoshis = Some(0); // Filled in in accept_channel
 
@@ -6063,12 +6220,12 @@ mod tests {
                                $( { $htlc_idx: expr, $counterparty_htlc_sig_hex: expr, $htlc_sig_hex: expr, $htlc_tx_hex: expr } ), *
                        } ) => { {
                                let (commitment_tx, htlcs): (_, Vec<HTLCOutputInCommitment>) = {
-                                       let mut res = chan.build_commitment_transaction(0xffffffffffff - 42, &keys, true, false, &logger);
+                                       let mut commitment_stats = chan.build_commitment_transaction(0xffffffffffff - 42, &keys, true, false, &logger);
 
-                                       let htlcs = res.3.drain(..)
+                                       let htlcs = commitment_stats.htlcs_included.drain(..)
                                                .filter_map(|(htlc, _)| if htlc.transaction_output_index.is_some() { Some(htlc) } else { None })
                                                .collect();
-                                       (res.0, htlcs)
+                                       (commitment_stats.tx, htlcs)
                                };
                                let trusted_tx = commitment_tx.trust();
                                let unsigned_tx = trusted_tx.built_transaction();
@@ -6109,10 +6266,11 @@ mod tests {
                                        let remote_signature = Signature::from_der(&hex::decode($counterparty_htlc_sig_hex).unwrap()[..]).unwrap();
 
                                        let ref htlc = htlcs[$htlc_idx];
+                                       let opt_anchors = false;
                                        let htlc_tx = chan_utils::build_htlc_transaction(&unsigned_tx.txid, chan.feerate_per_kw,
                                                chan.get_counterparty_selected_contest_delay().unwrap(),
-                                               &htlc, &keys.broadcaster_delayed_payment_key, &keys.revocation_key);
-                                       let htlc_redeemscript = chan_utils::get_htlc_redeemscript(&htlc, &keys);
+                                               &htlc, opt_anchors, &keys.broadcaster_delayed_payment_key, &keys.revocation_key);
+                                       let htlc_redeemscript = chan_utils::get_htlc_redeemscript(&htlc, opt_anchors, &keys);
                                        let htlc_sighash = Message::from_slice(&bip143::SigHashCache::new(&htlc_tx).signature_hash(0, &htlc_redeemscript, htlc.amount_msat / 1000, SigHashType::All)[..]).unwrap();
                                        secp_ctx.verify(&htlc_sighash, &remote_signature, &keys.countersignatory_htlc_key).unwrap();