Simplify call graph of get_update_fulfill_htlc since it can't Err.
[rust-lightning] / lightning / src / ln / channel.rs
index b940b45f7013e976e0c36d9abe1fde4de1c56ec1..f46d76042df91601e4bc278425906e40bf075e37 100644 (file)
@@ -15,6 +15,7 @@ use bitcoin::consensus::encode;
 
 use bitcoin::hashes::Hash;
 use bitcoin::hashes::sha256::Hash as Sha256;
+use bitcoin::hashes::sha256d::Hash as Sha256d;
 use bitcoin::hash_types::{Txid, BlockHash, WPubkeyHash};
 
 use bitcoin::secp256k1::key::{PublicKey,SecretKey};
@@ -25,9 +26,10 @@ use ln::{PaymentPreimage, PaymentHash};
 use ln::features::{ChannelFeatures, InitFeatures};
 use ln::msgs;
 use ln::msgs::{DecodeError, OptionalField, DataLossProtect};
-use ln::channelmanager::{BestBlock, PendingHTLCStatus, HTLCSource, HTLCFailReason, HTLCFailureMsg, PendingHTLCInfo, RAACommitmentOrder, BREAKDOWN_TIMEOUT, MIN_CLTV_EXPIRY_DELTA, MAX_LOCAL_BREAKDOWN_TIMEOUT};
+use ln::channelmanager::{PendingHTLCStatus, HTLCSource, HTLCFailReason, HTLCFailureMsg, PendingHTLCInfo, RAACommitmentOrder, BREAKDOWN_TIMEOUT, MIN_CLTV_EXPIRY_DELTA, MAX_LOCAL_BREAKDOWN_TIMEOUT};
 use ln::chan_utils::{CounterpartyCommitmentSecrets, TxCreationKeys, HTLCOutputInCommitment, HTLC_SUCCESS_TX_WEIGHT, HTLC_TIMEOUT_TX_WEIGHT, make_funding_redeemscript, ChannelPublicKeys, CommitmentTransaction, HolderCommitmentTransaction, ChannelTransactionParameters, CounterpartyChannelTransactionParameters, MAX_HTLCS, get_commitment_transaction_number_obscure_factor};
 use ln::chan_utils;
+use chain::BestBlock;
 use chain::chaininterface::{FeeEstimator,ConfirmationTarget};
 use chain::channelmonitor::{ChannelMonitor, ChannelMonitorUpdate, ChannelMonitorUpdateStep, HTLC_FAIL_BACK_BUFFER};
 use chain::transaction::{OutPoint, TransactionData};
@@ -39,6 +41,7 @@ use util::errors::APIError;
 use util::config::{UserConfig,ChannelConfig};
 use util::scid_utils::scid_from_parts;
 
+use prelude::*;
 use core::{cmp,mem,fmt};
 use core::ops::Deref;
 #[cfg(any(test, feature = "fuzztarget"))]
@@ -112,8 +115,8 @@ enum InboundHTLCState {
        /// commitment transaction without it as otherwise we'll have to force-close the channel to
        /// claim it before the timeout (obviously doesn't apply to revoked HTLCs that we can't claim
        /// anyway). That said, ChannelMonitor does this for us (see
-       /// ChannelMonitor::would_broadcast_at_height) so we actually remove the HTLC from our own
-       /// local state before then, once we're sure that the next commitment_signed and
+       /// ChannelMonitor::should_broadcast_holder_commitment_txn) so we actually remove the HTLC from
+       /// our own local state before then, once we're sure that the next commitment_signed and
        /// ChannelMonitor::provide_latest_local_commitment_tx will not include this HTLC.
        LocalRemoved(InboundHTLCRemovalReason),
 }
@@ -286,7 +289,7 @@ impl HTLCCandidate {
 }
 
 /// Information needed for constructing an invoice route hint for this channel.
-#[derive(Clone)]
+#[derive(Clone, Debug, PartialEq)]
 pub struct CounterpartyForwardingInfo {
        /// Base routing fee in millisatoshis.
        pub fee_base_msat: u32,
@@ -298,6 +301,33 @@ pub struct CounterpartyForwardingInfo {
        pub cltv_expiry_delta: u16,
 }
 
+/// A return value enum for get_update_fulfill_htlc. See UpdateFulfillCommitFetch variants for
+/// description
+enum UpdateFulfillFetch {
+       NewClaim {
+               monitor_update: ChannelMonitorUpdate,
+               msg: Option<msgs::UpdateFulfillHTLC>,
+       },
+       DuplicateClaim {},
+}
+
+/// The return type of get_update_fulfill_htlc_and_commit.
+pub enum UpdateFulfillCommitFetch {
+       /// Indicates the HTLC fulfill is new, and either generated an update_fulfill message, placed
+       /// it in the holding cell, or re-generated the update_fulfill message after the same claim was
+       /// previously placed in the holding cell (and has since been removed).
+       NewClaim {
+               /// The ChannelMonitorUpdate which places the new payment preimage in the channel monitor
+               monitor_update: ChannelMonitorUpdate,
+               /// The update_fulfill message and commitment_signed message (if the claim was not placed
+               /// in the holding cell).
+               msgs: Option<(msgs::UpdateFulfillHTLC, msgs::CommitmentSigned)>,
+       },
+       /// Indicates the HTLC fulfill is duplicative and already existed either in the holding cell
+       /// or has been forgotten (presumably previously claimed).
+       DuplicateClaim {},
+}
+
 // 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
@@ -394,7 +424,7 @@ pub(super) struct Channel<Signer: Sign> {
        counterparty_max_htlc_value_in_flight_msat: u64,
        //get_holder_max_htlc_value_in_flight_msat(): u64,
        /// minimum channel reserve for self to maintain - set by them.
-       counterparty_selected_channel_reserve_satoshis: u64,
+       counterparty_selected_channel_reserve_satoshis: Option<u64>,
        // get_holder_selected_channel_reserve_satoshis(channel_value_sats: u64): u64
        counterparty_htlc_minimum_msat: u64,
        holder_htlc_minimum_msat: u64,
@@ -403,7 +433,7 @@ pub(super) struct Channel<Signer: Sign> {
        #[cfg(not(test))]
        counterparty_max_accepted_htlcs: u16,
        //implied by OUR_MAX_HTLCS: max_accepted_htlcs: u16,
-       minimum_depth: u32,
+       minimum_depth: Option<u32>,
 
        counterparty_forwarding_info: Option<CounterpartyForwardingInfo>,
 
@@ -420,6 +450,10 @@ pub(super) struct Channel<Signer: Sign> {
 
        channel_update_status: ChannelUpdateStatus,
 
+       /// Our counterparty's channel_announcement signatures provided in announcement_signatures.
+       /// This can be used to rebroadcast the channel_announcement message later.
+       announcement_sigs: Option<(Signature, Signature)>,
+
        // We save these values so we can make sure `next_local_commit_tx_fee_msat` and
        // `next_remote_commit_tx_fee_msat` properly predict what the next commitment transaction fee will
        // be, by comparing the cached values to the fee of the tranaction generated by
@@ -428,6 +462,24 @@ pub(super) struct Channel<Signer: Sign> {
        next_local_commitment_tx_fee_info_cached: Mutex<Option<CommitmentTxInfoCached>>,
        #[cfg(any(test, feature = "fuzztarget"))]
        next_remote_commitment_tx_fee_info_cached: Mutex<Option<CommitmentTxInfoCached>>,
+
+       /// lnd has a long-standing bug where, upon reconnection, if the channel is not yet confirmed
+       /// they will not send a channel_reestablish until the channel locks in. Then, they will send a
+       /// funding_locked *before* sending the channel_reestablish (which is clearly a violation of
+       /// the BOLT specs). We copy c-lightning's workaround here and simply store the funding_locked
+       /// message until we receive a channel_reestablish.
+       ///
+       /// See-also <https://github.com/lightningnetwork/lnd/issues/4006>
+       pub workaround_lnd_bug_4006: Option<msgs::FundingLocked>,
+
+       #[cfg(any(test, feature = "fuzztarget"))]
+       // When we receive an HTLC fulfill on an outbound path, we may immediately fulfill the
+       // corresponding HTLC on the inbound path. If, then, the outbound path channel is
+       // disconnected and reconnected (before we've exchange commitment_signed and revoke_and_ack
+       // messages), they may re-broadcast their update_fulfill_htlc, causing a duplicate claim. This
+       // is fine, but as a sanity check in our failure to generate the second claim, we check here
+       // that the original was a claim, and that we aren't now trying to fulfill a failed HTLC.
+       historical_inbound_htlc_fulfills: HashSet<u64>,
 }
 
 #[cfg(any(test, feature = "fuzztarget"))]
@@ -594,11 +646,11 @@ impl<Signer: Sign> Channel<Signer> {
                        counterparty_dust_limit_satoshis: 0,
                        holder_dust_limit_satoshis: MIN_DUST_LIMIT_SATOSHIS,
                        counterparty_max_htlc_value_in_flight_msat: 0,
-                       counterparty_selected_channel_reserve_satoshis: 0,
+                       counterparty_selected_channel_reserve_satoshis: None, // Filled in in accept_channel
                        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,
-                       minimum_depth: 0, // Filled in in accept_channel
+                       minimum_depth: None, // Filled in in accept_channel
 
                        counterparty_forwarding_info: None,
 
@@ -621,10 +673,17 @@ impl<Signer: Sign> Channel<Signer> {
 
                        channel_update_status: ChannelUpdateStatus::Enabled,
 
+                       announcement_sigs: None,
+
                        #[cfg(any(test, feature = "fuzztarget"))]
                        next_local_commitment_tx_fee_info_cached: Mutex::new(None),
                        #[cfg(any(test, feature = "fuzztarget"))]
                        next_remote_commitment_tx_fee_info_cached: Mutex::new(None),
+
+                       workaround_lnd_bug_4006: None,
+
+                       #[cfg(any(test, feature = "fuzztarget"))]
+                       historical_inbound_htlc_fulfills: HashSet::new(),
                })
        }
 
@@ -832,11 +891,11 @@ impl<Signer: Sign> Channel<Signer> {
                        counterparty_dust_limit_satoshis: msg.dust_limit_satoshis,
                        holder_dust_limit_satoshis: MIN_DUST_LIMIT_SATOSHIS,
                        counterparty_max_htlc_value_in_flight_msat: cmp::min(msg.max_htlc_value_in_flight_msat, msg.funding_satoshis * 1000),
-                       counterparty_selected_channel_reserve_satoshis: msg.channel_reserve_satoshis,
+                       counterparty_selected_channel_reserve_satoshis: Some(msg.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,
-                       minimum_depth: config.own_channel_config.minimum_depth,
+                       minimum_depth: Some(config.own_channel_config.minimum_depth),
 
                        counterparty_forwarding_info: None,
 
@@ -862,10 +921,17 @@ impl<Signer: Sign> Channel<Signer> {
 
                        channel_update_status: ChannelUpdateStatus::Enabled,
 
+                       announcement_sigs: None,
+
                        #[cfg(any(test, feature = "fuzztarget"))]
                        next_local_commitment_tx_fee_info_cached: Mutex::new(None),
                        #[cfg(any(test, feature = "fuzztarget"))]
                        next_remote_commitment_tx_fee_info_cached: Mutex::new(None),
+
+                       workaround_lnd_bug_4006: None,
+
+                       #[cfg(any(test, feature = "fuzztarget"))]
+                       historical_inbound_htlc_fulfills: HashSet::new(),
                };
 
                Ok(chan)
@@ -899,7 +965,10 @@ impl<Signer: Sign> Channel<Signer> {
                let mut local_htlc_total_msat = 0;
                let mut value_to_self_msat_offset = 0;
 
-               log_trace!(logger, "Building commitment transaction number {} (really {} xor {}) for {}, generated by {} with fee {}...", commitment_number, (INITIAL_COMMITMENT_NUMBER - commitment_number), get_commitment_transaction_number_obscure_factor(&self.get_holder_pubkeys().payment_point, &self.get_counterparty_pubkeys().payment_point, self.is_outbound()), if local { "us" } else { "remote" }, if generated_by_local { "us" } else { "remote" }, feerate_per_kw);
+               log_trace!(logger, "Building commitment transaction number {} (really {} xor {}) for channel {} for {}, generated by {} with fee {}...",
+                       commitment_number, (INITIAL_COMMITMENT_NUMBER - commitment_number),
+                       get_commitment_transaction_number_obscure_factor(&self.get_holder_pubkeys().payment_point, &self.get_counterparty_pubkeys().payment_point, self.is_outbound()),
+                       log_bytes!(self.channel_id), if local { "us" } else { "remote" }, if generated_by_local { "us" } else { "remote" }, feerate_per_kw);
 
                macro_rules! get_htlc_in_commitment {
                        ($htlc: expr, $offered: expr) => {
@@ -1010,7 +1079,7 @@ impl<Signer: Sign> Channel<Signer> {
                        } else {
                                self.counterparty_max_commitment_tx_output.lock().unwrap()
                        };
-                       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 as i64);
+                       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);
                        broadcaster_max_commitment_tx_output.1 = cmp::max(broadcaster_max_commitment_tx_output.1, value_to_remote_msat as u64);
@@ -1190,20 +1259,7 @@ impl<Signer: Sign> Channel<Signer> {
                make_funding_redeemscript(&self.get_holder_pubkeys().funding_pubkey, self.counterparty_funding_pubkey())
        }
 
-       /// Builds the htlc-success or htlc-timeout transaction which spends a given HTLC output
-       /// @local is used only to convert relevant internal structures which refer to remote vs local
-       /// to decide value of outputs and direction of HTLCs.
-       fn build_htlc_transaction(&self, prev_hash: &Txid, htlc: &HTLCOutputInCommitment, local: bool, keys: &TxCreationKeys, feerate_per_kw: u32) -> Transaction {
-               chan_utils::build_htlc_transaction(prev_hash, feerate_per_kw, if local { self.get_counterparty_selected_contest_delay() } else { self.get_holder_selected_contest_delay() }, htlc, &keys.broadcaster_delayed_payment_key, &keys.revocation_key)
-       }
-
-       /// Per HTLC, only one get_update_fail_htlc or get_update_fulfill_htlc call may be made.
-       /// In such cases we debug_assert!(false) and return a ChannelError::Ignore. Thus, will always
-       /// return Ok(_) if debug assertions are turned on or preconditions are met.
-       ///
-       /// Note that it is still possible to hit these assertions in case we find a preimage on-chain
-       /// but then have a reorg which settles on an HTLC-failure on chain.
-       fn get_update_fulfill_htlc<L: Deref>(&mut self, htlc_id_arg: u64, payment_preimage_arg: PaymentPreimage, logger: &L) -> Result<(Option<msgs::UpdateFulfillHTLC>, Option<ChannelMonitorUpdate>), ChannelError> where L::Target: Logger {
+       fn get_update_fulfill_htlc<L: Deref>(&mut self, htlc_id_arg: u64, payment_preimage_arg: PaymentPreimage, logger: &L) -> UpdateFulfillFetch where L::Target: Logger {
                // Either ChannelFunded got set (which means it won't be unset) or there is no way any
                // caller thought we could have something claimed (cause we wouldn't have accepted in an
                // incoming HTLC anyway). If we got to ShutdownComplete, callers aren't allowed to call us,
@@ -1229,9 +1285,9 @@ impl<Signer: Sign> Channel<Signer> {
                                                if let &InboundHTLCRemovalReason::Fulfill(_) = reason {
                                                } else {
                                                        log_warn!(logger, "Have preimage and want to fulfill HTLC with payment hash {} we already failed against channel {}", log_bytes!(htlc.payment_hash.0), log_bytes!(self.channel_id()));
+                                                       debug_assert!(false, "Tried to fulfill an HTLC that was already failed");
                                                }
-                                               debug_assert!(false, "Tried to fulfill an HTLC that was already fail/fulfilled");
-                                               return Ok((None, None));
+                                               return UpdateFulfillFetch::DuplicateClaim {};
                                        },
                                        _ => {
                                                debug_assert!(false, "Have an inbound HTLC we tried to claim before it was fully committed to");
@@ -1243,7 +1299,11 @@ impl<Signer: Sign> Channel<Signer> {
                        }
                }
                if pending_idx == core::usize::MAX {
-                       return Err(ChannelError::Ignore("Unable to find a pending HTLC which matched the given HTLC ID".to_owned()));
+                       #[cfg(any(test, feature = "fuzztarget"))]
+                       // If we failed to find an HTLC to fulfill, make sure it was previously fulfilled and
+                       // this is simply a duplicate claim, not previously failed and we lost funds.
+                       debug_assert!(self.historical_inbound_htlc_fulfills.contains(&htlc_id_arg));
+                       return UpdateFulfillFetch::DuplicateClaim {};
                }
 
                // Now update local state:
@@ -1265,8 +1325,9 @@ impl<Signer: Sign> Channel<Signer> {
                                                if htlc_id_arg == htlc_id {
                                                        // Make sure we don't leave latest_monitor_update_id incremented here:
                                                        self.latest_monitor_update_id -= 1;
-                                                       debug_assert!(false, "Tried to fulfill an HTLC that was already fulfilled");
-                                                       return Ok((None, None));
+                                                       #[cfg(any(test, feature = "fuzztarget"))]
+                                                       debug_assert!(self.historical_inbound_htlc_fulfills.contains(&htlc_id_arg));
+                                                       return UpdateFulfillFetch::DuplicateClaim {};
                                                }
                                        },
                                        &HTLCUpdateAwaitingACK::FailHTLC { htlc_id, .. } => {
@@ -1275,63 +1336,66 @@ impl<Signer: Sign> Channel<Signer> {
                                                        // TODO: We may actually be able to switch to a fulfill here, though its
                                                        // rare enough it may not be worth the complexity burden.
                                                        debug_assert!(false, "Tried to fulfill an HTLC that was already failed");
-                                                       return Ok((None, Some(monitor_update)));
+                                                       return UpdateFulfillFetch::NewClaim { monitor_update, msg: None };
                                                }
                                        },
                                        _ => {}
                                }
                        }
-                       log_trace!(logger, "Adding HTLC claim to holding_cell! Current state: {}", self.channel_state);
+                       log_trace!(logger, "Adding HTLC claim to holding_cell in channel {}! Current state: {}", log_bytes!(self.channel_id()), self.channel_state);
                        self.holding_cell_htlc_updates.push(HTLCUpdateAwaitingACK::ClaimHTLC {
                                payment_preimage: payment_preimage_arg, htlc_id: htlc_id_arg,
                        });
-                       return Ok((None, Some(monitor_update)));
+                       #[cfg(any(test, feature = "fuzztarget"))]
+                       self.historical_inbound_htlc_fulfills.insert(htlc_id_arg);
+                       return UpdateFulfillFetch::NewClaim { monitor_update, msg: None };
                }
+               #[cfg(any(test, feature = "fuzztarget"))]
+               self.historical_inbound_htlc_fulfills.insert(htlc_id_arg);
 
                {
                        let htlc = &mut self.pending_inbound_htlcs[pending_idx];
                        if let InboundHTLCState::Committed = htlc.state {
                        } else {
                                debug_assert!(false, "Have an inbound HTLC we tried to claim before it was fully committed to");
-                               return Ok((None, Some(monitor_update)));
+                               return UpdateFulfillFetch::NewClaim { monitor_update, msg: None };
                        }
-                       log_trace!(logger, "Upgrading HTLC {} to LocalRemoved with a Fulfill!", log_bytes!(htlc.payment_hash.0));
+                       log_trace!(logger, "Upgrading HTLC {} to LocalRemoved with a Fulfill in channel {}!", log_bytes!(htlc.payment_hash.0), log_bytes!(self.channel_id));
                        htlc.state = InboundHTLCState::LocalRemoved(InboundHTLCRemovalReason::Fulfill(payment_preimage_arg.clone()));
                }
 
-               Ok((Some(msgs::UpdateFulfillHTLC {
-                       channel_id: self.channel_id(),
-                       htlc_id: htlc_id_arg,
-                       payment_preimage: payment_preimage_arg,
-               }), Some(monitor_update)))
+               UpdateFulfillFetch::NewClaim {
+                       monitor_update,
+                       msg: Some(msgs::UpdateFulfillHTLC {
+                               channel_id: self.channel_id(),
+                               htlc_id: htlc_id_arg,
+                               payment_preimage: payment_preimage_arg,
+                       }),
+               }
        }
 
-       pub fn get_update_fulfill_htlc_and_commit<L: Deref>(&mut self, htlc_id: u64, payment_preimage: PaymentPreimage, logger: &L) -> Result<(Option<(msgs::UpdateFulfillHTLC, msgs::CommitmentSigned)>, Option<ChannelMonitorUpdate>), ChannelError> where L::Target: Logger {
-               match self.get_update_fulfill_htlc(htlc_id, payment_preimage, logger)? {
-                       (Some(update_fulfill_htlc), Some(mut monitor_update)) => {
+       pub fn get_update_fulfill_htlc_and_commit<L: Deref>(&mut self, htlc_id: u64, payment_preimage: PaymentPreimage, logger: &L) -> Result<UpdateFulfillCommitFetch, ChannelError> where L::Target: Logger {
+               match self.get_update_fulfill_htlc(htlc_id, payment_preimage, logger) {
+                       UpdateFulfillFetch::NewClaim { mut monitor_update, msg: Some(update_fulfill_htlc) } => {
                                let (commitment, mut additional_update) = self.send_commitment_no_status_check(logger)?;
                                // send_commitment_no_status_check may bump latest_monitor_id but we want them to be
                                // strictly increasing by one, so decrement it here.
                                self.latest_monitor_update_id = monitor_update.update_id;
                                monitor_update.updates.append(&mut additional_update.updates);
-                               Ok((Some((update_fulfill_htlc, commitment)), Some(monitor_update)))
-                       },
-                       (Some(update_fulfill_htlc), None) => {
-                               let (commitment, monitor_update) = self.send_commitment_no_status_check(logger)?;
-                               Ok((Some((update_fulfill_htlc, commitment)), Some(monitor_update)))
+                               Ok(UpdateFulfillCommitFetch::NewClaim { monitor_update, msgs: Some((update_fulfill_htlc, commitment)) })
                        },
-                       (None, Some(monitor_update)) => Ok((None, Some(monitor_update))),
-                       (None, None) => Ok((None, None))
+                       UpdateFulfillFetch::NewClaim { monitor_update, msg: None } => Ok(UpdateFulfillCommitFetch::NewClaim { monitor_update, msgs: None }),
+                       UpdateFulfillFetch::DuplicateClaim {} => Ok(UpdateFulfillCommitFetch::DuplicateClaim {}),
                }
        }
 
-       /// Per HTLC, only one get_update_fail_htlc or get_update_fulfill_htlc call may be made.
-       /// In such cases we debug_assert!(false) and return a ChannelError::Ignore. Thus, will always
-       /// return Ok(_) if debug assertions are turned on or preconditions are met.
-       ///
-       /// Note that it is still possible to hit these assertions in case we find a preimage on-chain
-       /// but then have a reorg which settles on an HTLC-failure on chain.
-       pub fn get_update_fail_htlc(&mut self, htlc_id_arg: u64, err_packet: msgs::OnionErrorPacket) -> Result<Option<msgs::UpdateFailHTLC>, ChannelError> {
+       /// We can only have one resolution per HTLC. In some cases around reconnect, we may fulfill
+       /// an HTLC more than once or fulfill once and then attempt to fail after reconnect. We cannot,
+       /// however, fail more than once as we wait for an upstream failure to be irrevocably committed
+       /// before we fail backwards.
+       /// If we do fail twice, we debug_assert!(false) and return Ok(None). Thus, will always return
+       /// Ok(_) if debug assertions are turned on or preconditions are met.
+       pub fn get_update_fail_htlc<L: Deref>(&mut self, htlc_id_arg: u64, err_packet: msgs::OnionErrorPacket, logger: &L) -> Result<Option<msgs::UpdateFailHTLC>, ChannelError> where L::Target: Logger {
                if (self.channel_state & (ChannelState::ChannelFunded as u32)) != (ChannelState::ChannelFunded as u32) {
                        panic!("Was asked to fail an HTLC when channel was not in an operational state");
                }
@@ -1346,8 +1410,11 @@ impl<Signer: Sign> Channel<Signer> {
                        if htlc.htlc_id == htlc_id_arg {
                                match htlc.state {
                                        InboundHTLCState::Committed => {},
-                                       InboundHTLCState::LocalRemoved(_) => {
-                                               debug_assert!(false, "Tried to fail an HTLC that was already fail/fulfilled");
+                                       InboundHTLCState::LocalRemoved(ref reason) => {
+                                               if let &InboundHTLCRemovalReason::Fulfill(_) = reason {
+                                               } else {
+                                                       debug_assert!(false, "Tried to fail an HTLC that was already failed");
+                                               }
                                                return Ok(None);
                                        },
                                        _ => {
@@ -1359,7 +1426,11 @@ impl<Signer: Sign> Channel<Signer> {
                        }
                }
                if pending_idx == core::usize::MAX {
-                       return Err(ChannelError::Ignore("Unable to find a pending HTLC which matched the given HTLC ID".to_owned()));
+                       #[cfg(any(test, feature = "fuzztarget"))]
+                       // If we failed to find an HTLC to fail, make sure it was previously fulfilled and this
+                       // is simply a duplicate fail, not previously failed and we failed-back too early.
+                       debug_assert!(self.historical_inbound_htlc_fulfills.contains(&htlc_id_arg));
+                       return Ok(None);
                }
 
                // Now update local state:
@@ -1368,8 +1439,9 @@ impl<Signer: Sign> Channel<Signer> {
                                match pending_update {
                                        &HTLCUpdateAwaitingACK::ClaimHTLC { htlc_id, .. } => {
                                                if htlc_id_arg == htlc_id {
-                                                       debug_assert!(false, "Tried to fail an HTLC that was already fulfilled");
-                                                       return Err(ChannelError::Ignore("Unable to find a pending HTLC which matched the given HTLC ID".to_owned()));
+                                                       #[cfg(any(test, feature = "fuzztarget"))]
+                                                       debug_assert!(self.historical_inbound_htlc_fulfills.contains(&htlc_id_arg));
+                                                       return Ok(None);
                                                }
                                        },
                                        &HTLCUpdateAwaitingACK::FailHTLC { htlc_id, .. } => {
@@ -1381,6 +1453,7 @@ impl<Signer: Sign> Channel<Signer> {
                                        _ => {}
                                }
                        }
+                       log_trace!(logger, "Placing failure for HTLC ID {} in holding cell in channel {}.", htlc_id_arg, log_bytes!(self.channel_id()));
                        self.holding_cell_htlc_updates.push(HTLCUpdateAwaitingACK::FailHTLC {
                                htlc_id: htlc_id_arg,
                                err_packet,
@@ -1388,6 +1461,7 @@ impl<Signer: Sign> Channel<Signer> {
                        return Ok(None);
                }
 
+               log_trace!(logger, "Failing HTLC ID {} back with a update_fail_htlc message in channel {}.", htlc_id_arg, log_bytes!(self.channel_id()));
                {
                        let htlc = &mut self.pending_inbound_htlcs[pending_idx];
                        htlc.state = InboundHTLCState::LocalRemoved(InboundHTLCRemovalReason::FailRelay(err_packet.clone()));
@@ -1416,9 +1490,6 @@ 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.dust_limit_satoshis > msg.channel_reserve_satoshis {
-                       return Err(ChannelError::Close(format!("Bogus channel_reserve ({}) and dust_limit ({})", msg.channel_reserve_satoshis, msg.dust_limit_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)));
                }
@@ -1463,6 +1534,12 @@ impl<Signer: Sign> Channel<Signer> {
                if msg.minimum_depth > config.peer_channel_config_limits.max_minimum_depth {
                        return Err(ChannelError::Close(format!("We consider the minimum depth to be unreasonably large. Expected minimum: ({}). Actual: ({})", config.peer_channel_config_limits.max_minimum_depth, msg.minimum_depth)));
                }
+               if msg.minimum_depth == 0 {
+                       // Note that if this changes we should update the serialization minimum version to
+                       // indicate to older clients that they don't understand some features of the current
+                       // channel.
+                       return Err(ChannelError::Close("Minimum confirmation depth must be at least 1".to_owned()));
+               }
 
                let counterparty_shutdown_scriptpubkey = if their_features.supports_upfront_shutdown_script() {
                        match &msg.shutdown_scriptpubkey {
@@ -1486,10 +1563,10 @@ impl<Signer: Sign> Channel<Signer> {
 
                self.counterparty_dust_limit_satoshis = msg.dust_limit_satoshis;
                self.counterparty_max_htlc_value_in_flight_msat = cmp::min(msg.max_htlc_value_in_flight_msat, self.channel_value_satoshis * 1000);
-               self.counterparty_selected_channel_reserve_satoshis = msg.channel_reserve_satoshis;
+               self.counterparty_selected_channel_reserve_satoshis = Some(msg.channel_reserve_satoshis);
                self.counterparty_htlc_minimum_msat = msg.htlc_minimum_msat;
                self.counterparty_max_accepted_htlcs = msg.max_accepted_htlcs;
-               self.minimum_depth = msg.minimum_depth;
+               self.minimum_depth = Some(msg.minimum_depth);
 
                let counterparty_pubkeys = ChannelPublicKeys {
                        funding_pubkey: msg.funding_pubkey,
@@ -1522,7 +1599,10 @@ impl<Signer: Sign> Channel<Signer> {
                        let initial_commitment_bitcoin_tx = trusted_tx.built_transaction();
                        let sighash = initial_commitment_bitcoin_tx.get_sighash_all(&funding_script, self.channel_value_satoshis);
                        // They sign the holder commitment transaction...
-                       log_trace!(logger, "Checking funding_created tx signature {} by key {} against tx {} (sighash {}) with redeemscript {}", log_bytes!(sig.serialize_compact()[..]), log_bytes!(self.counterparty_funding_pubkey().serialize()), encode::serialize_hex(&initial_commitment_bitcoin_tx.transaction), log_bytes!(sighash[..]), encode::serialize_hex(&funding_script));
+                       log_trace!(logger, "Checking funding_created tx signature {} by key {} against tx {} (sighash {}) with redeemscript {} for channel {}.",
+                               log_bytes!(sig.serialize_compact()[..]), log_bytes!(self.counterparty_funding_pubkey().serialize()),
+                               encode::serialize_hex(&initial_commitment_bitcoin_tx.transaction), log_bytes!(sighash[..]),
+                               encode::serialize_hex(&funding_script), log_bytes!(self.channel_id()));
                        secp_check!(self.secp_ctx.verify(&sighash, &sig, self.counterparty_funding_pubkey()), "Invalid funding_created signature from peer".to_owned());
                }
 
@@ -1531,7 +1611,8 @@ impl<Signer: Sign> Channel<Signer> {
 
                let counterparty_trusted_tx = counterparty_initial_commitment_tx.trust();
                let counterparty_initial_bitcoin_tx = counterparty_trusted_tx.built_transaction();
-               log_trace!(logger, "Initial counterparty ID {} tx {}", counterparty_initial_bitcoin_tx.txid, encode::serialize_hex(&counterparty_initial_bitcoin_tx.transaction));
+               log_trace!(logger, "Initial counterparty tx for channel {} is: txid {} tx {}",
+                       log_bytes!(self.channel_id()), counterparty_initial_bitcoin_tx.txid, encode::serialize_hex(&counterparty_initial_bitcoin_tx.transaction));
 
                let counterparty_signature = 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;
@@ -1607,6 +1688,8 @@ impl<Signer: Sign> Channel<Signer> {
                self.cur_counterparty_commitment_transaction_number -= 1;
                self.cur_holder_commitment_transaction_number -= 1;
 
+               log_info!(logger, "Generated funding_signed for peer for channel {}", log_bytes!(self.channel_id()));
+
                Ok((msgs::FundingSigned {
                        channel_id: self.channel_id,
                        signature
@@ -1635,7 +1718,8 @@ impl<Signer: Sign> Channel<Signer> {
                let counterparty_trusted_tx = counterparty_initial_commitment_tx.trust();
                let counterparty_initial_bitcoin_tx = counterparty_trusted_tx.built_transaction();
 
-               log_trace!(logger, "Initial counterparty ID {} tx {}", counterparty_initial_bitcoin_tx.txid, encode::serialize_hex(&counterparty_initial_bitcoin_tx.transaction));
+               log_trace!(logger, "Initial counterparty tx for channel {} is: txid {} tx {}",
+                       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, self.feerate_per_kw, logger).0;
@@ -1677,12 +1761,15 @@ impl<Signer: Sign> Channel<Signer> {
                self.cur_holder_commitment_transaction_number -= 1;
                self.cur_counterparty_commitment_transaction_number -= 1;
 
+               log_info!(logger, "Received funding_signed from peer for channel {}", log_bytes!(self.channel_id()));
+
                Ok((channel_monitor, self.funding_transaction.as_ref().cloned().unwrap()))
        }
 
-       pub fn funding_locked(&mut self, msg: &msgs::FundingLocked) -> Result<(), ChannelError> {
+       pub fn funding_locked<L: Deref>(&mut self, msg: &msgs::FundingLocked, logger: &L) -> Result<(), ChannelError> where L::Target: Logger {
                if self.channel_state & (ChannelState::PeerDisconnected as u32) == ChannelState::PeerDisconnected as u32 {
-                       return Err(ChannelError::Close("Peer sent funding_locked when we needed a channel_reestablish".to_owned()));
+                       self.workaround_lnd_bug_4006 = Some(msg.clone());
+                       return Err(ChannelError::Ignore("Peer sent funding_locked when we needed a channel_reestablish. The peer is likely lnd, see https://github.com/lightningnetwork/lnd/issues/4006".to_owned()));
                }
 
                let non_shutdown_state = self.channel_state & (!MULTI_STATE_FLAGS);
@@ -1710,6 +1797,9 @@ impl<Signer: Sign> Channel<Signer> {
 
                self.counterparty_prev_commitment_point = self.counterparty_cur_commitment_point;
                self.counterparty_cur_commitment_point = Some(msg.next_per_commitment_point);
+
+               log_info!(logger, "Received funding_locked from peer for channel {}", log_bytes!(self.channel_id()));
+
                Ok(())
        }
 
@@ -1747,8 +1837,22 @@ impl<Signer: Sign> Channel<Signer> {
        /// corner case properly.
        pub fn get_inbound_outbound_available_balance_msat(&self) -> (u64, u64) {
                // Note that we have to handle overflow due to the above case.
-               (cmp::max(self.channel_value_satoshis as i64 * 1000 - self.value_to_self_msat as i64 - self.get_inbound_pending_htlc_stats().1 as i64, 0) as u64,
-               cmp::max(self.value_to_self_msat as i64 - self.get_outbound_pending_htlc_stats().1 as i64, 0) as u64)
+               (
+                       cmp::max(self.channel_value_satoshis as i64 * 1000
+                               - self.value_to_self_msat as i64
+                               - self.get_inbound_pending_htlc_stats().1 as i64
+                               - Self::get_holder_selected_channel_reserve_satoshis(self.channel_value_satoshis) as i64 * 1000,
+                       0) as u64,
+                       cmp::max(self.value_to_self_msat as i64
+                               - self.get_outbound_pending_htlc_stats().1 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)
        }
 
        // Get the fee cost of a commitment tx with a given number of HTLC outputs.
@@ -2019,14 +2123,14 @@ impl<Signer: Sign> Channel<Signer> {
                        if pending_remote_value_msat - msg.amount_msat - chan_reserve_msat < 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");
+                               log_info!(logger, "Attempting to fail HTLC due to fee spike buffer violation in channel {}. Rebalancing is required.", log_bytes!(self.channel_id()));
                                pending_forward_status = create_pending_htlc_status(self, pending_forward_status, 0x1000|7);
                        }
                } else {
                        // Check that they won't violate our local required channel reserve by adding this HTLC.
                        let htlc_candidate = HTLCCandidate::new(msg.amount_msat, HTLCInitiator::RemoteOffered);
                        let local_commit_tx_fee_msat = self.next_local_commit_tx_fee_msat(htlc_candidate, None);
-                       if self.value_to_self_msat < self.counterparty_selected_channel_reserve_satoshis * 1000 + local_commit_tx_fee_msat {
+                       if self.value_to_self_msat < self.counterparty_selected_channel_reserve_satoshis.unwrap() * 1000 + local_commit_tx_fee_msat {
                                return Err(ChannelError::Close("Cannot accept HTLC that would put our balance under counterparty-announced channel reserve value".to_owned()));
                        }
                }
@@ -2151,7 +2255,10 @@ impl<Signer: Sign> Channel<Signer> {
                                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 {}", 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_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())));
                                }
@@ -2195,10 +2302,15 @@ impl<Signer: Sign> Channel<Signer> {
                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 = self.build_htlc_transaction(&commitment_txid, &htlc, true, &keys, feerate_per_kw);
+                               let htlc_tx = chan_utils::build_htlc_transaction(&commitment_txid, feerate_per_kw,
+                                       self.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);
                                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 {}", log_bytes!(msg.htlc_signatures[idx].serialize_compact()[..]), log_bytes!(keys.countersignatory_htlc_key.serialize()), encode::serialize_hex(&htlc_tx), log_bytes!(htlc_sighash[..]), encode::serialize_hex(&htlc_redeemscript));
+                               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()),
+                                       encode::serialize_hex(&htlc_tx), log_bytes!(htlc_sighash[..]), encode::serialize_hex(&htlc_redeemscript), log_bytes!(self.channel_id()));
                                if let Err(_) = self.secp_ctx.verify(&htlc_sighash, &msg.htlc_signatures[idx], &keys.countersignatory_htlc_key) {
                                        return Err((None, ChannelError::Close("Invalid HTLC tx signature from peer".to_owned())));
                                }
@@ -2248,6 +2360,8 @@ impl<Signer: Sign> Channel<Signer> {
                                Some(forward_info.clone())
                        } else { None };
                        if let Some(forward_info) = new_forward {
+                               log_trace!(logger, "Updating HTLC {} to AwaitingRemoteRevokeToAnnounce due to commitment_signed in channel {}.",
+                                       log_bytes!(htlc.payment_hash.0), log_bytes!(self.channel_id));
                                htlc.state = InboundHTLCState::AwaitingRemoteRevokeToAnnounce(forward_info);
                                need_commitment = true;
                        }
@@ -2256,6 +2370,8 @@ impl<Signer: Sign> Channel<Signer> {
                        if let Some(fail_reason) = if let &mut OutboundHTLCState::RemoteRemoved(ref mut fail_reason) = &mut htlc.state {
                                Some(fail_reason.take())
                        } else { None } {
+                               log_trace!(logger, "Updating HTLC {} to AwaitingRemoteRevokeToRemove due to commitment_signed in channel {}.",
+                                       log_bytes!(htlc.payment_hash.0), log_bytes!(self.channel_id));
                                htlc.state = OutboundHTLCState::AwaitingRemoteRevokeToRemove(fail_reason);
                                need_commitment = true;
                        }
@@ -2281,6 +2397,8 @@ impl<Signer: Sign> Channel<Signer> {
                                self.latest_monitor_update_id = monitor_update.update_id;
                                monitor_update.updates.append(&mut additional_update.updates);
                        }
+                       log_debug!(logger, "Received valid commitment_signed from peer in channel {}, updated HTLC state but awaiting a monitor update resolution to reply.",
+                               log_bytes!(self.channel_id));
                        // TODO: Call maybe_propose_first_closing_signed on restoration (or call it here and
                        // re-send the message on restoration)
                        return Err((Some(monitor_update), ChannelError::Ignore("Previous monitor update failure prevented generation of RAA".to_owned())));
@@ -2300,6 +2418,9 @@ impl<Signer: Sign> Channel<Signer> {
                        (None, self.maybe_propose_first_closing_signed(fee_estimator))
                } else { (None, None) };
 
+               log_debug!(logger, "Received valid commitment_signed from peer in channel {}, updating HTLC state and responding with{} a revoke_and_ack.",
+                       log_bytes!(self.channel_id()), if commitment_signed.is_some() { " our own commitment_signed and" } else { "" });
+
                Ok((msgs::RevokeAndACK {
                        channel_id: self.channel_id,
                        per_commitment_secret,
@@ -2307,12 +2428,23 @@ impl<Signer: Sign> Channel<Signer> {
                }, commitment_signed, closing_signed, monitor_update))
        }
 
+       /// Public version of the below, checking relevant preconditions first.
+       /// If we're not in a state where freeing the holding cell makes sense, this is a no-op and
+       /// returns `(None, Vec::new())`.
+       pub fn maybe_free_holding_cell_htlcs<L: Deref>(&mut self, logger: &L) -> Result<(Option<(msgs::CommitmentUpdate, ChannelMonitorUpdate)>, Vec<(HTLCSource, PaymentHash)>), ChannelError> where L::Target: Logger {
+               if self.channel_state >= ChannelState::ChannelFunded as u32 &&
+                  (self.channel_state & (ChannelState::AwaitingRemoteRevoke as u32 | ChannelState::PeerDisconnected as u32 | ChannelState::MonitorUpdateFailed as u32)) == 0 {
+                       self.free_holding_cell_htlcs(logger)
+               } else { Ok((None, Vec::new())) }
+       }
+
        /// Used to fulfill holding_cell_htlcs when we get a remote ack (or implicitly get it by them
        /// fulfilling or failing the last pending HTLC)
        fn free_holding_cell_htlcs<L: Deref>(&mut self, logger: &L) -> Result<(Option<(msgs::CommitmentUpdate, ChannelMonitorUpdate)>, Vec<(HTLCSource, PaymentHash)>), ChannelError> where L::Target: Logger {
                assert_eq!(self.channel_state & ChannelState::MonitorUpdateFailed as u32, 0);
                if self.holding_cell_htlc_updates.len() != 0 || self.holding_cell_update_fee.is_some() {
-                       log_trace!(logger, "Freeing holding cell with {} HTLC updates{}", self.holding_cell_htlc_updates.len(), if self.holding_cell_update_fee.is_some() { " and a fee update" } else { "" });
+                       log_trace!(logger, "Freeing holding cell with {} HTLC updates{} in channel {}", self.holding_cell_htlc_updates.len(),
+                               if self.holding_cell_update_fee.is_some() { " and a fee update" } else { "" }, log_bytes!(self.channel_id()));
 
                        let mut monitor_update = ChannelMonitorUpdate {
                                update_id: self.latest_monitor_update_id + 1, // We don't increment this yet!
@@ -2338,7 +2470,8 @@ impl<Signer: Sign> Channel<Signer> {
                                                        Err(e) => {
                                                                match e {
                                                                        ChannelError::Ignore(ref msg) => {
-                                                                               log_info!(logger, "Failed to send HTLC with payment_hash {} due to {}", log_bytes!(payment_hash.0), msg);
+                                                                               log_info!(logger, "Failed to send HTLC with payment_hash {} due to {} in channel {}",
+                                                                                       log_bytes!(payment_hash.0), msg, log_bytes!(self.channel_id()));
                                                                                // If we fail to send here, then this HTLC should
                                                                                // be failed backwards. Failing to send here
                                                                                // indicates that this HTLC may keep being put back
@@ -2355,24 +2488,28 @@ impl<Signer: Sign> Channel<Signer> {
                                                }
                                        },
                                        &HTLCUpdateAwaitingACK::ClaimHTLC { ref payment_preimage, htlc_id, .. } => {
-                                               match self.get_update_fulfill_htlc(htlc_id, *payment_preimage, logger) {
-                                                       Ok((update_fulfill_msg_option, additional_monitor_update_opt)) => {
-                                                               update_fulfill_htlcs.push(update_fulfill_msg_option.unwrap());
-                                                               if let Some(mut additional_monitor_update) = additional_monitor_update_opt {
-                                                                       monitor_update.updates.append(&mut additional_monitor_update.updates);
-                                                               }
-                                                       },
-                                                       Err(e) => {
-                                                               if let ChannelError::Ignore(_) = e {}
-                                                               else {
-                                                                       panic!("Got a non-IgnoreError action trying to fulfill holding cell HTLC");
-                                                               }
-                                                       }
-                                               }
+                                               // If an HTLC claim was previously added to the holding cell (via
+                                               // `get_update_fulfill_htlc`, then generating the claim message itself must
+                                               // not fail - any in between attempts to claim the HTLC will have resulted
+                                               // in it hitting the holding cell again and we cannot change the state of a
+                                               // holding cell HTLC from fulfill to anything else.
+                                               let (update_fulfill_msg_option, mut additional_monitor_update) =
+                                                       if let UpdateFulfillFetch::NewClaim { msg, monitor_update } = self.get_update_fulfill_htlc(htlc_id, *payment_preimage, logger) {
+                                                               (msg, monitor_update)
+                                                       } else { unreachable!() };
+                                               update_fulfill_htlcs.push(update_fulfill_msg_option.unwrap());
+                                               monitor_update.updates.append(&mut additional_monitor_update.updates);
                                        },
                                        &HTLCUpdateAwaitingACK::FailHTLC { htlc_id, ref err_packet } => {
-                                               match self.get_update_fail_htlc(htlc_id, err_packet.clone()) {
-                                                       Ok(update_fail_msg_option) => update_fail_htlcs.push(update_fail_msg_option.unwrap()),
+                                               match self.get_update_fail_htlc(htlc_id, err_packet.clone(), logger) {
+                                                       Ok(update_fail_msg_option) => {
+                                                               // If an HTLC failure was previously added to the holding cell (via
+                                                               // `get_update_fail_htlc`) then generating the fail message itself
+                                                               // must not fail - we should never end up in a state where we
+                                                               // double-fail an HTLC or fail-then-claim an HTLC as it indicates
+                                                               // we didn't wait for a full revocation before failing.
+                                                               update_fail_htlcs.push(update_fail_msg_option.unwrap())
+                                                       },
                                                        Err(e) => {
                                                                if let ChannelError::Ignore(_) = e {}
                                                                else {
@@ -2402,6 +2539,10 @@ impl<Signer: Sign> Channel<Signer> {
                        self.latest_monitor_update_id = monitor_update.update_id;
                        monitor_update.updates.append(&mut additional_update.updates);
 
+                       log_debug!(logger, "Freeing holding cell in channel {} resulted in {}{} HTLCs added, {} HTLCs fulfilled, and {} HTLCs failed.",
+                               log_bytes!(self.channel_id()), if update_fee.is_some() { "a fee update, " } else { "" },
+                               update_add_htlcs.len(), update_fulfill_htlcs.len(), update_fail_htlcs.len());
+
                        Ok((Some((msgs::CommitmentUpdate {
                                update_add_htlcs,
                                update_fulfill_htlcs,
@@ -2477,7 +2618,7 @@ impl<Signer: Sign> Channel<Signer> {
                self.counterparty_cur_commitment_point = Some(msg.next_per_commitment_point);
                self.cur_counterparty_commitment_transaction_number -= 1;
 
-               log_trace!(logger, "Updating HTLCs on receipt of RAA...");
+               log_trace!(logger, "Updating HTLCs on receipt of RAA in channel {}...", log_bytes!(self.channel_id()));
                let mut to_forward_infos = Vec::new();
                let mut revoked_htlcs = Vec::new();
                let mut update_fail_htlcs = Vec::new();
@@ -2514,10 +2655,8 @@ impl<Signer: Sign> Channel<Signer> {
                        });
                        for htlc in pending_inbound_htlcs.iter_mut() {
                                let swap = if let &InboundHTLCState::AwaitingRemoteRevokeToAnnounce(_) = &htlc.state {
-                                       log_trace!(logger, " ...promoting inbound AwaitingRemoteRevokeToAnnounce {} to Committed", log_bytes!(htlc.payment_hash.0));
                                        true
                                } else if let &InboundHTLCState::AwaitingAnnouncedRemoteRevoke(_) = &htlc.state {
-                                       log_trace!(logger, " ...promoting inbound AwaitingAnnouncedRemoteRevoke {} to Committed", log_bytes!(htlc.payment_hash.0));
                                        true
                                } else { false };
                                if swap {
@@ -2525,11 +2664,13 @@ impl<Signer: Sign> Channel<Signer> {
                                        mem::swap(&mut state, &mut htlc.state);
 
                                        if let InboundHTLCState::AwaitingRemoteRevokeToAnnounce(forward_info) = state {
+                                               log_trace!(logger, " ...promoting inbound AwaitingRemoteRevokeToAnnounce {} to AwaitingAnnouncedRemoteRevoke", log_bytes!(htlc.payment_hash.0));
                                                htlc.state = InboundHTLCState::AwaitingAnnouncedRemoteRevoke(forward_info);
                                                require_commitment = true;
                                        } else if let InboundHTLCState::AwaitingAnnouncedRemoteRevoke(forward_info) = state {
                                                match forward_info {
                                                        PendingHTLCStatus::Fail(fail_msg) => {
+                                                               log_trace!(logger, " ...promoting inbound AwaitingAnnouncedRemoteRevoke {} to LocalRemoved due to PendingHTLCStatus indicating failure", log_bytes!(htlc.payment_hash.0));
                                                                require_commitment = true;
                                                                match fail_msg {
                                                                        HTLCFailureMsg::Relay(msg) => {
@@ -2543,6 +2684,7 @@ impl<Signer: Sign> Channel<Signer> {
                                                                }
                                                        },
                                                        PendingHTLCStatus::Forward(forward_info) => {
+                                                               log_trace!(logger, " ...promoting inbound AwaitingAnnouncedRemoteRevoke {} to Committed", log_bytes!(htlc.payment_hash.0));
                                                                to_forward_infos.push((forward_info, htlc.htlc_id));
                                                                htlc.state = InboundHTLCState::Committed;
                                                        }
@@ -2600,6 +2742,7 @@ impl<Signer: Sign> Channel<Signer> {
                        }
                        self.monitor_pending_forwards.append(&mut to_forward_infos);
                        self.monitor_pending_failures.append(&mut revoked_htlcs);
+                       log_debug!(logger, "Received a valid revoke_and_ack for channel {} but awaiting a monitor update resolution to reply.", log_bytes!(self.channel_id()));
                        return Ok((None, Vec::new(), Vec::new(), None, monitor_update, Vec::new()))
                }
 
@@ -2630,6 +2773,8 @@ impl<Signer: Sign> Channel<Signer> {
                                        self.latest_monitor_update_id = monitor_update.update_id;
                                        monitor_update.updates.append(&mut additional_update.updates);
 
+                                       log_debug!(logger, "Received a valid revoke_and_ack for channel {}. Responding with a commitment update with {} HTLCs failed.",
+                                               log_bytes!(self.channel_id()), update_fail_htlcs.len() + update_fail_malformed_htlcs.len());
                                        Ok((Some(msgs::CommitmentUpdate {
                                                update_add_htlcs: Vec::new(),
                                                update_fulfill_htlcs: Vec::new(),
@@ -2639,6 +2784,7 @@ impl<Signer: Sign> Channel<Signer> {
                                                commitment_signed
                                        }), to_forward_infos, revoked_htlcs, None, monitor_update, htlcs_to_fail))
                                } else {
+                                       log_debug!(logger, "Received a valid revoke_and_ack for channel {} with no reply necessary.", log_bytes!(self.channel_id()));
                                        Ok((None, to_forward_infos, revoked_htlcs, self.maybe_propose_first_closing_signed(fee_estimator), monitor_update, htlcs_to_fail))
                                }
                        }
@@ -2684,19 +2830,16 @@ impl<Signer: Sign> Channel<Signer> {
                }
        }
 
-       /// Removes any uncommitted HTLCs, to be used on peer disconnection, including any pending
-       /// HTLCs that we intended to add but haven't as we were waiting on a remote revoke.
-       /// Returns the set of PendingHTLCStatuses from remote uncommitted HTLCs (which we're
-       /// implicitly dropping) and the payment_hashes of HTLCs we tried to add but are dropping.
+       /// Removes any uncommitted inbound HTLCs and resets the state of uncommitted outbound HTLC
+       /// updates, to be used on peer disconnection. After this, update_*_htlc messages need to be
+       /// resent.
        /// No further message handling calls may be made until a channel_reestablish dance has
        /// completed.
-       pub fn remove_uncommitted_htlcs_and_mark_paused<L: Deref>(&mut self, logger: &L) -> Vec<(HTLCSource, PaymentHash)> where L::Target: Logger {
-               let mut outbound_drops = Vec::new();
-
+       pub fn remove_uncommitted_htlcs_and_mark_paused<L: Deref>(&mut self, logger: &L)  where L::Target: Logger {
                assert_eq!(self.channel_state & ChannelState::ShutdownComplete as u32, 0);
                if self.channel_state < ChannelState::FundingSent as u32 {
                        self.channel_state = ChannelState::ShutdownComplete as u32;
-                       return outbound_drops;
+                       return;
                }
                // Upon reconnect we have to start the closing_signed dance over, but shutdown messages
                // will be retransmitted.
@@ -2739,23 +2882,8 @@ impl<Signer: Sign> Channel<Signer> {
                        }
                }
 
-               self.holding_cell_htlc_updates.retain(|htlc_update| {
-                       match htlc_update {
-                               // Note that currently on channel reestablish we assert that there are
-                               // no holding cell HTLC update_adds, so if in the future we stop
-                               // dropping added HTLCs here and failing them backwards, then there will
-                               // need to be corresponding changes made in the Channel's re-establish
-                               // logic.
-                               &HTLCUpdateAwaitingACK::AddHTLC { ref payment_hash, ref source, .. } => {
-                                       outbound_drops.push((source.clone(), payment_hash.clone()));
-                                       false
-                               },
-                               &HTLCUpdateAwaitingACK::ClaimHTLC {..} | &HTLCUpdateAwaitingACK::FailHTLC {..} => true,
-                       }
-               });
                self.channel_state |= ChannelState::PeerDisconnected as u32;
-               log_debug!(logger, "Peer disconnection resulted in {} remote-announced HTLC drops and {} waiting-to-locally-announced HTLC drops on channel {}", outbound_drops.len(), inbound_drop_count, log_bytes!(self.channel_id()));
-               outbound_drops
+               log_trace!(logger, "Peer disconnection resulted in {} remote-announced HTLC drops on channel {}", inbound_drop_count, log_bytes!(self.channel_id()));
        }
 
        /// Indicates that a ChannelMonitor update failed to be stored by the client and further
@@ -2822,10 +2950,9 @@ impl<Signer: Sign> Channel<Signer> {
                self.monitor_pending_revoke_and_ack = false;
                self.monitor_pending_commitment_signed = false;
                let order = self.resend_order.clone();
-               log_trace!(logger, "Restored monitor updating resulting in {}{} commitment update and {} RAA, with {} first",
-                       if funding_broadcastable.is_some() { "a funding broadcastable, " } else { "" },
-                       if commitment_update.is_some() { "a" } else { "no" },
-                       if raa.is_some() { "an" } else { "no" },
+               log_debug!(logger, "Restored monitor updating in channel {} resulting in {}{} commitment update and {} RAA, with {} first",
+                       log_bytes!(self.channel_id()), if funding_broadcastable.is_some() { "a funding broadcastable, " } else { "" },
+                       if commitment_update.is_some() { "a" } else { "no" }, if raa.is_some() { "an" } else { "no" },
                        match order { RAACommitmentOrder::CommitmentFirst => "commitment", RAACommitmentOrder::RevokeAndACKFirst => "RAA"});
                (raa, commitment_update, order, forwards, failures, funding_broadcastable, funding_locked)
        }
@@ -2903,8 +3030,8 @@ impl<Signer: Sign> Channel<Signer> {
                        }
                }
 
-               log_trace!(logger, "Regenerated latest commitment update with {} update_adds, {} update_fulfills, {} update_fails, and {} update_fail_malformeds",
-                               update_add_htlcs.len(), update_fulfill_htlcs.len(), update_fail_htlcs.len(), update_fail_malformed_htlcs.len());
+               log_trace!(logger, "Regenerated latest commitment update in channel {} with {} update_adds, {} update_fulfills, {} update_fails, and {} update_fail_malformeds",
+                               log_bytes!(self.channel_id()), update_add_htlcs.len(), update_fulfill_htlcs.len(), update_fail_htlcs.len(), update_fail_malformed_htlcs.len());
                msgs::CommitmentUpdate {
                        update_add_htlcs, update_fulfill_htlcs, update_fail_htlcs, update_fail_malformed_htlcs,
                        update_fee: None,
@@ -2914,7 +3041,7 @@ impl<Signer: Sign> Channel<Signer> {
 
        /// May panic if some calls other than message-handling calls (which will all Err immediately)
        /// have been called between remove_uncommitted_htlcs_and_mark_paused and this call.
-       pub fn channel_reestablish<L: Deref>(&mut self, msg: &msgs::ChannelReestablish, logger: &L) -> Result<(Option<msgs::FundingLocked>, Option<msgs::RevokeAndACK>, Option<msgs::CommitmentUpdate>, Option<ChannelMonitorUpdate>, RAACommitmentOrder, Option<msgs::Shutdown>), ChannelError> where L::Target: Logger {
+       pub fn channel_reestablish<L: Deref>(&mut self, msg: &msgs::ChannelReestablish, logger: &L) -> Result<(Option<msgs::FundingLocked>, Option<msgs::RevokeAndACK>, Option<msgs::CommitmentUpdate>, Option<ChannelMonitorUpdate>, RAACommitmentOrder, Vec<(HTLCSource, PaymentHash)>, Option<msgs::Shutdown>), ChannelError> where L::Target: Logger {
                if self.channel_state & (ChannelState::PeerDisconnected as u32) == 0 {
                        // While BOLT 2 doesn't indicate explicitly we should error this channel here, it
                        // almost certainly indicates we are going to end up out-of-sync in some way, so we
@@ -2965,7 +3092,7 @@ impl<Signer: Sign> Channel<Signer> {
                                        return Err(ChannelError::Close("Peer claimed they saw a revoke_and_ack but we haven't sent funding_locked yet".to_owned()));
                                }
                                // Short circuit the whole handler as there is nothing we can resend them
-                               return Ok((None, None, None, None, RAACommitmentOrder::CommitmentFirst, shutdown_msg));
+                               return Ok((None, None, None, None, RAACommitmentOrder::CommitmentFirst, Vec::new(), shutdown_msg));
                        }
 
                        // We have OurFundingLocked set!
@@ -2973,7 +3100,7 @@ impl<Signer: Sign> Channel<Signer> {
                        return Ok((Some(msgs::FundingLocked {
                                channel_id: self.channel_id(),
                                next_per_commitment_point,
-                       }), None, None, None, RAACommitmentOrder::CommitmentFirst, shutdown_msg));
+                       }), None, None, None, RAACommitmentOrder::CommitmentFirst, Vec::new(), shutdown_msg));
                }
 
                let required_revoke = if msg.next_remote_commitment_number + 1 == INITIAL_COMMITMENT_NUMBER - self.cur_holder_commitment_transaction_number {
@@ -3014,14 +3141,6 @@ impl<Signer: Sign> Channel<Signer> {
                        }
 
                        if (self.channel_state & (ChannelState::AwaitingRemoteRevoke as u32 | ChannelState::MonitorUpdateFailed as u32)) == 0 {
-                               // Note that if in the future we no longer drop holding cell update_adds on peer
-                               // disconnect, this logic will need to be updated.
-                               for htlc_update in self.holding_cell_htlc_updates.iter() {
-                                       if let &HTLCUpdateAwaitingACK::AddHTLC { .. } = htlc_update {
-                                               debug_assert!(false, "There shouldn't be any add-HTLCs in the holding cell now because they should have been dropped on peer disconnect. Panic here because said HTLCs won't be handled correctly.");
-                                       }
-                               }
-
                                // We're up-to-date and not waiting on a remote revoke (if we are our
                                // channel_reestablish should result in them sending a revoke_and_ack), but we may
                                // have received some updates while we were disconnected. Free the holding cell
@@ -3030,20 +3149,14 @@ impl<Signer: Sign> Channel<Signer> {
                                        Err(ChannelError::Close(msg)) => return Err(ChannelError::Close(msg)),
                                        Err(ChannelError::Ignore(_)) | Err(ChannelError::CloseDelayBroadcast(_)) => panic!("Got non-channel-failing result from free_holding_cell_htlcs"),
                                        Ok((Some((commitment_update, monitor_update)), htlcs_to_fail)) => {
-                                               // If in the future we no longer drop holding cell update_adds on peer
-                                               // disconnect, we may be handed some HTLCs to fail backwards here.
-                                               assert!(htlcs_to_fail.is_empty());
-                                               return Ok((resend_funding_locked, required_revoke, Some(commitment_update), Some(monitor_update), self.resend_order.clone(), shutdown_msg));
+                                               return Ok((resend_funding_locked, required_revoke, Some(commitment_update), Some(monitor_update), self.resend_order.clone(), htlcs_to_fail, shutdown_msg));
                                        },
                                        Ok((None, htlcs_to_fail)) => {
-                                               // If in the future we no longer drop holding cell update_adds on peer
-                                               // disconnect, we may be handed some HTLCs to fail backwards here.
-                                               assert!(htlcs_to_fail.is_empty());
-                                               return Ok((resend_funding_locked, required_revoke, None, None, self.resend_order.clone(), shutdown_msg));
+                                               return Ok((resend_funding_locked, required_revoke, None, None, self.resend_order.clone(), htlcs_to_fail, shutdown_msg));
                                        },
                                }
                        } else {
-                               return Ok((resend_funding_locked, required_revoke, None, None, self.resend_order.clone(), shutdown_msg));
+                               return Ok((resend_funding_locked, required_revoke, None, None, self.resend_order.clone(), Vec::new(), shutdown_msg));
                        }
                } else if msg.next_local_commitment_number == next_counterparty_commitment_number - 1 {
                        if required_revoke.is_some() {
@@ -3054,10 +3167,10 @@ impl<Signer: Sign> Channel<Signer> {
 
                        if self.channel_state & (ChannelState::MonitorUpdateFailed as u32) != 0 {
                                self.monitor_pending_commitment_signed = true;
-                               return Ok((resend_funding_locked, None, None, None, self.resend_order.clone(), shutdown_msg));
+                               return Ok((resend_funding_locked, None, None, None, self.resend_order.clone(), Vec::new(), shutdown_msg));
                        }
 
-                       return Ok((resend_funding_locked, required_revoke, Some(self.get_last_commitment_update(logger)), None, self.resend_order.clone(), shutdown_msg));
+                       return Ok((resend_funding_locked, required_revoke, Some(self.get_last_commitment_update(logger)), None, self.resend_order.clone(), Vec::new(), shutdown_msg));
                } else {
                        return Err(ChannelError::Close("Peer attempted to reestablish channel with a very old remote commitment transaction".to_owned()));
                }
@@ -3296,6 +3409,10 @@ impl<Signer: Sign> Channel<Signer> {
                self.channel_id
        }
 
+       pub fn minimum_depth(&self) -> Option<u32> {
+               self.minimum_depth
+       }
+
        /// Gets the "user_id" value passed into the construction of this channel. It has no special
        /// meaning and exists only to allow users to have a persistent identifier of a channel.
        pub fn get_user_id(&self) -> u64 {
@@ -3323,8 +3440,9 @@ impl<Signer: Sign> Channel<Signer> {
                &self.channel_transaction_parameters.holder_pubkeys
        }
 
-       fn get_counterparty_selected_contest_delay(&self) -> u16 {
-               self.channel_transaction_parameters.counterparty_parameters.as_ref().unwrap().selected_contest_delay
+       pub fn get_counterparty_selected_contest_delay(&self) -> Option<u16> {
+               self.channel_transaction_parameters.counterparty_parameters
+                       .as_ref().map(|params| params.selected_contest_delay)
        }
 
        fn get_counterparty_pubkeys(&self) -> &ChannelPublicKeys {
@@ -3398,7 +3516,7 @@ impl<Signer: Sign> Channel<Signer> {
                ChannelValueStat {
                        value_to_self_msat: self.value_to_self_msat,
                        channel_value_msat: self.channel_value_satoshis * 1000,
-                       channel_reserve_msat: self.counterparty_selected_channel_reserve_satoshis * 1000,
+                       channel_reserve_msat: self.counterparty_selected_channel_reserve_satoshis.unwrap() * 1000,
                        pending_outbound_htlcs_amount_msat: self.pending_outbound_htlcs.iter().map(|ref h| h.amount_msat).sum::<u64>(),
                        pending_inbound_htlcs_amount_msat: self.pending_inbound_htlcs.iter().map(|ref h| h.amount_msat).sum::<u64>(),
                        holding_cell_outbound_amount_msat: {
@@ -3473,7 +3591,7 @@ impl<Signer: Sign> Channel<Signer> {
        /// is_usable() and considers things like the channel being temporarily disabled.
        /// Allowed in any state (including after shutdown)
        pub fn is_live(&self) -> bool {
-               self.is_usable() && (self.channel_state & (ChannelState::PeerDisconnected as u32 | ChannelState::MonitorUpdateFailed as u32) == 0)
+               self.is_usable() && (self.channel_state & (ChannelState::PeerDisconnected as u32) == 0)
        }
 
        /// Returns true if this channel has been marked as awaiting a monitor update to move forward.
@@ -3515,7 +3633,7 @@ impl<Signer: Sign> Channel<Signer> {
                        self.funding_tx_confirmation_height = 0;
                }
 
-               if funding_tx_confirmations < self.minimum_depth as i64 {
+               if funding_tx_confirmations < self.minimum_depth.unwrap_or(0) as i64 {
                        return None;
                }
 
@@ -3603,12 +3721,13 @@ impl<Signer: Sign> Channel<Signer> {
                                        // send it immediately instead of waiting for a best_block_updated call (which
                                        // may have already happened for this block).
                                        if let Some(funding_locked) = self.check_get_funding_locked(height) {
+                                               log_info!(logger, "Sending a funding_locked to our peer for channel {}", log_bytes!(self.channel_id));
                                                return Ok(Some(funding_locked));
                                        }
                                }
                                for inp in tx.input.iter() {
                                        if inp.previous_output == funding_txo.into_bitcoin_outpoint() {
-                                               log_trace!(logger, "Detected channel-closing tx {} spending {}:{}, closing channel {}", tx.txid(), inp.previous_output.txid, inp.previous_output.vout, log_bytes!(self.channel_id()));
+                                               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()
@@ -3631,7 +3750,8 @@ 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(&mut self, height: u32, highest_header_time: u32) -> Result<(Option<msgs::FundingLocked>, Vec<(HTLCSource, PaymentHash)>), msgs::ErrorMessage> {
+       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 {
                let mut timed_out_htlcs = Vec::new();
                let unforwarded_htlc_cltv_limit = height + HTLC_FAIL_BACK_BUFFER;
                self.holding_cell_htlc_updates.retain(|htlc_update| {
@@ -3649,6 +3769,7 @@ impl<Signer: Sign> Channel<Signer> {
                self.update_time_counter = cmp::max(self.update_time_counter, highest_header_time);
 
                if let Some(funding_locked) = self.check_get_funding_locked(height) {
+                       log_info!(logger, "Sending a funding_locked to our peer for channel {}", log_bytes!(self.channel_id));
                        return Ok((Some(funding_locked), timed_out_htlcs));
                }
 
@@ -3667,10 +3788,10 @@ impl<Signer: Sign> Channel<Signer> {
                        // the funding transaction's confirmation count has dipped below minimum_depth / 2,
                        // 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 as i64 / 2 {
+                       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, funding_tx_confirmations),
+                                       data: format!("Funding transaction was un-confirmed. Locked at {} confs, now have {} confs.", self.minimum_depth.unwrap(), funding_tx_confirmations),
                                });
                        }
                }
@@ -3681,7 +3802,7 @@ 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(&mut self) -> Result<(), msgs::ErrorMessage> {
+       pub fn funding_transaction_unconfirmed<L: Deref>(&mut self, logger: &L) -> Result<(), msgs::ErrorMessage> 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.
@@ -3690,7 +3811,7 @@ impl<Signer: Sign> Channel<Signer> {
                        // larger. If we don't know that time has moved forward, we can just set it to the last
                        // time we saw and it will be ignored.
                        let best_time = self.update_time_counter;
-                       match self.best_block_updated(reorg_height, best_time) {
+                       match self.best_block_updated(reorg_height, best_time, logger) {
                                Ok((funding_locked, timed_out_htlcs)) => {
                                        assert!(funding_locked.is_none(), "We can't generate a funding with 0 confirmations?");
                                        assert!(timed_out_htlcs.is_empty(), "We can't have accepted HTLCs with a timeout before our funding confirmation?");
@@ -3765,7 +3886,7 @@ impl<Signer: Sign> Channel<Signer> {
                        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),
                        htlc_minimum_msat: self.holder_htlc_minimum_msat,
-                       minimum_depth: self.minimum_depth,
+                       minimum_depth: self.minimum_depth.unwrap(),
                        to_self_delay: self.get_holder_selected_contest_delay(),
                        max_accepted_htlcs: OUR_MAX_HTLCS,
                        funding_pubkey: keys.funding_pubkey,
@@ -3842,6 +3963,8 @@ impl<Signer: Sign> Channel<Signer> {
        /// closing).
        /// Note that the "channel must be funded" requirement is stricter than BOLT 7 requires - see
        /// https://github.com/lightningnetwork/lightning-rfc/issues/468
+       ///
+       /// This will only return ChannelError::Ignore upon failure.
        pub fn get_channel_announcement(&self, node_id: PublicKey, chain_hash: BlockHash) -> Result<(msgs::UnsignedChannelAnnouncement, Signature), ChannelError> {
                if !self.config.announced_channel {
                        return Err(ChannelError::Ignore("Channel is not available for public announcements".to_owned()));
@@ -3872,6 +3995,63 @@ impl<Signer: Sign> Channel<Signer> {
                Ok((msg, sig))
        }
 
+       /// Signs the given channel announcement, returning a ChannelError::Ignore if no keys are
+       /// available.
+       fn sign_channel_announcement(&self, our_node_secret: &SecretKey, our_node_id: PublicKey, msghash: secp256k1::Message, announcement: msgs::UnsignedChannelAnnouncement, our_bitcoin_sig: Signature) -> Result<msgs::ChannelAnnouncement, ChannelError> {
+               if let Some((their_node_sig, their_bitcoin_sig)) = self.announcement_sigs {
+                       let were_node_one = announcement.node_id_1 == our_node_id;
+
+                       let our_node_sig = self.secp_ctx.sign(&msghash, our_node_secret);
+                       Ok(msgs::ChannelAnnouncement {
+                               node_signature_1: if were_node_one { our_node_sig } else { their_node_sig },
+                               node_signature_2: if were_node_one { their_node_sig } else { our_node_sig },
+                               bitcoin_signature_1: if were_node_one { our_bitcoin_sig } else { their_bitcoin_sig },
+                               bitcoin_signature_2: if were_node_one { their_bitcoin_sig } else { our_bitcoin_sig },
+                               contents: announcement,
+                       })
+               } else {
+                       Err(ChannelError::Ignore("Attempted to sign channel announcement before we'd received announcement_signatures".to_string()))
+               }
+       }
+
+       /// Processes an incoming announcement_signatures message, providing a fully-signed
+       /// channel_announcement message which we can broadcast and storing our counterparty's
+       /// signatures for later reconstruction/rebroadcast of the channel_announcement.
+       pub fn announcement_signatures(&mut self, our_node_secret: &SecretKey, our_node_id: PublicKey, chain_hash: BlockHash, msg: &msgs::AnnouncementSignatures) -> Result<msgs::ChannelAnnouncement, ChannelError> {
+               let (announcement, our_bitcoin_sig) = self.get_channel_announcement(our_node_id.clone(), chain_hash)?;
+
+               let msghash = hash_to_message!(&Sha256d::hash(&announcement.encode()[..])[..]);
+
+               if self.secp_ctx.verify(&msghash, &msg.node_signature, &self.get_counterparty_node_id()).is_err() {
+                       return Err(ChannelError::Close(format!(
+                               "Bad announcement_signatures. Failed to verify node_signature. UnsignedChannelAnnouncement used for verification is {:?}. their_node_key is {:?}",
+                                &announcement, self.get_counterparty_node_id())));
+               }
+               if self.secp_ctx.verify(&msghash, &msg.bitcoin_signature, self.counterparty_funding_pubkey()).is_err() {
+                       return Err(ChannelError::Close(format!(
+                               "Bad announcement_signatures. Failed to verify bitcoin_signature. UnsignedChannelAnnouncement used for verification is {:?}. their_bitcoin_key is ({:?})",
+                               &announcement, self.counterparty_funding_pubkey())));
+               }
+
+               self.announcement_sigs = Some((msg.node_signature, msg.bitcoin_signature));
+
+               self.sign_channel_announcement(our_node_secret, our_node_id, msghash, announcement, our_bitcoin_sig)
+       }
+
+       /// Gets a signed channel_announcement for this channel, if we previously received an
+       /// announcement_signatures from our counterparty.
+       pub fn get_signed_channel_announcement(&self, our_node_secret: &SecretKey, our_node_id: PublicKey, chain_hash: BlockHash) -> Option<msgs::ChannelAnnouncement> {
+               let (announcement, our_bitcoin_sig) = match self.get_channel_announcement(our_node_id.clone(), chain_hash) {
+                       Ok(res) => res,
+                       Err(_) => return None,
+               };
+               let msghash = hash_to_message!(&Sha256d::hash(&announcement.encode()[..])[..]);
+               match self.sign_channel_announcement(our_node_secret, our_node_id, msghash, announcement, our_bitcoin_sig) {
+                       Ok(res) => Some(res),
+                       Err(_) => None,
+               }
+       }
+
        /// May panic if called on a channel that wasn't immediately-previously
        /// self.remove_uncommitted_htlcs_and_mark_paused()'d
        pub fn get_channel_reestablish<L: Deref>(&self, logger: &L) -> msgs::ChannelReestablish where L::Target: Logger {
@@ -3887,13 +4067,13 @@ impl<Signer: Sign> Channel<Signer> {
                let dummy_pubkey = PublicKey::from_slice(&pk).unwrap();
                let data_loss_protect = if self.cur_counterparty_commitment_transaction_number + 1 < INITIAL_COMMITMENT_NUMBER {
                        let remote_last_secret = self.commitment_secrets.get_secret(self.cur_counterparty_commitment_transaction_number + 2).unwrap();
-                       log_trace!(logger, "Enough info to generate a Data Loss Protect with per_commitment_secret {}", log_bytes!(remote_last_secret));
+                       log_trace!(logger, "Enough info to generate a Data Loss Protect with per_commitment_secret {} for channel {}", log_bytes!(remote_last_secret), log_bytes!(self.channel_id()));
                        OptionalField::Present(DataLossProtect {
                                your_last_per_commitment_secret: remote_last_secret,
                                my_current_per_commitment_point: dummy_pubkey
                        })
                } else {
-                       log_info!(logger, "Sending a data_loss_protect with no previous remote per_commitment_secret");
+                       log_info!(logger, "Sending a data_loss_protect with no previous remote per_commitment_secret for channel {}", log_bytes!(self.channel_id()));
                        OptionalField::Present(DataLossProtect {
                                your_last_per_commitment_secret: [0;32],
                                my_current_per_commitment_point: dummy_pubkey,
@@ -3928,10 +4108,18 @@ impl<Signer: Sign> Channel<Signer> {
 
        /// Adds a pending outbound HTLC to this channel, note that you probably want
        /// send_htlc_and_commit instead cause you'll want both messages at once.
-       /// This returns an option instead of a pure UpdateAddHTLC as we may be in a state where we are
-       /// waiting on the remote peer to send us a revoke_and_ack during which time we cannot add new
-       /// HTLCs on the wire or we wouldn't be able to determine what they actually ACK'ed.
-       /// You MUST call send_commitment prior to any other calls on this Channel
+       ///
+       /// This returns an optional UpdateAddHTLC as we may be in a state where we cannot add HTLCs on
+       /// the wire:
+       /// * In cases where we're waiting on the remote peer to send us a revoke_and_ack, we
+       ///   wouldn't be able to determine what they actually ACK'ed if we have two sets of updates
+       ///   awaiting ACK.
+       /// * In cases where we're marked MonitorUpdateFailed, we cannot commit to a new state as we
+       ///   may not yet have sent the previous commitment update messages and will need to regenerate
+       ///   them.
+       ///
+       /// 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> {
                if (self.channel_state & (ChannelState::ChannelFunded as u32 | BOTH_SIDES_SHUTDOWN_MASK)) != (ChannelState::ChannelFunded as u32) {
@@ -3950,14 +4138,14 @@ impl<Signer: Sign> Channel<Signer> {
                        return Err(ChannelError::Ignore(format!("Cannot send less than their minimum HTLC value ({})", self.counterparty_htlc_minimum_msat)));
                }
 
-               if (self.channel_state & (ChannelState::PeerDisconnected as u32 | ChannelState::MonitorUpdateFailed as u32)) != 0 {
+               if (self.channel_state & (ChannelState::PeerDisconnected as u32)) != 0 {
                        // Note that this should never really happen, if we're !is_live() on receipt of an
                        // incoming HTLC for relay will result in us rejecting the HTLC and we won't allow
                        // the user to send directly into a !is_live() channel. However, if we
                        // disconnected during the time the previous hop was doing the commitment dance we may
                        // end up getting here after the forwarding delay. In any case, returning an
                        // IgnoreError will get ChannelManager to do the right thing and fail backwards now.
-                       return Err(ChannelError::Ignore("Cannot send an HTLC while disconnected/frozen for channel monitor update".to_owned()));
+                       return Err(ChannelError::Ignore("Cannot send an HTLC while disconnected from channel counterparty".to_owned()));
                }
 
                let (outbound_htlc_count, htlc_outbound_value_msat) = self.get_outbound_pending_htlc_stats();
@@ -3996,13 +4184,13 @@ impl<Signer: Sign> Channel<Signer> {
 
                // 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 * 1000;
+               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 {
                        return Err(ChannelError::Ignore(format!("Cannot send value that would put our balance under counterparty-announced channel reserve value ({})", chan_reserve_msat)));
                }
 
                // Now update local state:
-               if (self.channel_state & (ChannelState::AwaitingRemoteRevoke as u32)) == (ChannelState::AwaitingRemoteRevoke as u32) {
+               if (self.channel_state & (ChannelState::AwaitingRemoteRevoke as u32 | ChannelState::MonitorUpdateFailed as u32)) != 0 {
                        self.holding_cell_htlc_updates.push(HTLCUpdateAwaitingACK::AddHTLC {
                                amount_msat,
                                payment_hash,
@@ -4160,18 +4348,17 @@ impl<Signer: Sign> Channel<Signer> {
                        signature = res.0;
                        htlc_signatures = res.1;
 
-                       log_trace!(logger, "Signed remote commitment tx {} (txid {}) with redeemscript {} -> {}",
+                       log_trace!(logger, "Signed remote commitment tx {} (txid {}) with redeemscript {} -> {} in channel {}",
                                encode::serialize_hex(&counterparty_commitment_tx.0.trust().built_transaction().transaction),
-                               &counterparty_commitment_txid,
-                               encode::serialize_hex(&self.get_funding_redeemscript()),
-                               log_bytes!(signature.serialize_compact()[..]));
+                               &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 {} -> {}",
+                               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)),
                                        log_bytes!(counterparty_keys.broadcaster_htlc_key.serialize()),
-                                       log_bytes!(htlc_sig.serialize_compact()[..]));
+                                       log_bytes!(htlc_sig.serialize_compact()[..]), log_bytes!(self.channel_id()));
                        }
                }
 
@@ -4202,8 +4389,7 @@ impl<Signer: Sign> Channel<Signer> {
        }
 
        pub fn channel_update(&mut self, msg: &msgs::ChannelUpdate) -> Result<(), ChannelError> {
-               let usable_channel_value_msat = (self.channel_value_satoshis - self.counterparty_selected_channel_reserve_satoshis) * 1000;
-               if msg.contents.htlc_minimum_msat >= usable_channel_value_msat {
+               if msg.contents.htlc_minimum_msat >= self.channel_value_satoshis * 1000 {
                        return Err(ChannelError::Close("Minimum htlc value is greater than channel value".to_string()));
                }
                self.counterparty_forwarding_info = Some(CounterpartyForwardingInfo {
@@ -4333,37 +4519,11 @@ fn is_unsupported_shutdown_script(their_features: &InitFeatures, script: &Script
 const SERIALIZATION_VERSION: u8 = 1;
 const MIN_SERIALIZATION_VERSION: u8 = 1;
 
-impl Writeable for InboundHTLCRemovalReason {
-       fn write<W: Writer>(&self, writer: &mut W) -> Result<(), ::std::io::Error> {
-               match self {
-                       &InboundHTLCRemovalReason::FailRelay(ref error_packet) => {
-                               0u8.write(writer)?;
-                               error_packet.write(writer)?;
-                       },
-                       &InboundHTLCRemovalReason::FailMalformed((ref onion_hash, ref err_code)) => {
-                               1u8.write(writer)?;
-                               onion_hash.write(writer)?;
-                               err_code.write(writer)?;
-                       },
-                       &InboundHTLCRemovalReason::Fulfill(ref payment_preimage) => {
-                               2u8.write(writer)?;
-                               payment_preimage.write(writer)?;
-                       },
-               }
-               Ok(())
-       }
-}
-
-impl Readable for InboundHTLCRemovalReason {
-       fn read<R: ::std::io::Read>(reader: &mut R) -> Result<Self, DecodeError> {
-               Ok(match <u8 as Readable>::read(reader)? {
-                       0 => InboundHTLCRemovalReason::FailRelay(Readable::read(reader)?),
-                       1 => InboundHTLCRemovalReason::FailMalformed((Readable::read(reader)?, Readable::read(reader)?)),
-                       2 => InboundHTLCRemovalReason::Fulfill(Readable::read(reader)?),
-                       _ => return Err(DecodeError::InvalidValue),
-               })
-       }
-}
+impl_writeable_tlv_based_enum!(InboundHTLCRemovalReason,;
+       (0, FailRelay),
+       (1, FailMalformed),
+       (2, Fulfill),
+);
 
 impl Writeable for ChannelUpdateStatus {
        fn write<W: Writer>(&self, writer: &mut W) -> Result<(), ::std::io::Error> {
@@ -4393,10 +4553,9 @@ impl Readable for ChannelUpdateStatus {
 impl<Signer: Sign> Writeable for Channel<Signer> {
        fn write<W: Writer>(&self, writer: &mut W) -> Result<(), ::std::io::Error> {
                // Note that we write out as if remove_uncommitted_htlcs_and_mark_paused had just been
-               // called but include holding cell updates (and obviously we don't modify self).
+               // called.
 
-               writer.write_all(&[SERIALIZATION_VERSION; 1])?;
-               writer.write_all(&[MIN_SERIALIZATION_VERSION; 1])?;
+               write_ver_prefix!(writer, SERIALIZATION_VERSION, MIN_SERIALIZATION_VERSION);
 
                self.user_id.write(writer)?;
                self.config.write(writer)?;
@@ -4471,9 +4630,10 @@ impl<Signer: Sign> Writeable for Channel<Signer> {
                                &OutboundHTLCState::Committed => {
                                        1u8.write(writer)?;
                                },
-                               &OutboundHTLCState::RemoteRemoved(ref fail_reason) => {
-                                       2u8.write(writer)?;
-                                       fail_reason.write(writer)?;
+                               &OutboundHTLCState::RemoteRemoved(_) => {
+                                       // Treat this as a Committed because we haven't received the CS - they'll
+                                       // resend the claim/fail on reconnect as we all (hopefully) the missing CS.
+                                       1u8.write(writer)?;
                                },
                                &OutboundHTLCState::AwaitingRemoteRevokeToRemove(ref fail_reason) => {
                                        3u8.write(writer)?;
@@ -4557,11 +4717,11 @@ impl<Signer: Sign> Writeable for Channel<Signer> {
                self.counterparty_dust_limit_satoshis.write(writer)?;
                self.holder_dust_limit_satoshis.write(writer)?;
                self.counterparty_max_htlc_value_in_flight_msat.write(writer)?;
-               self.counterparty_selected_channel_reserve_satoshis.write(writer)?;
+               self.counterparty_selected_channel_reserve_satoshis.unwrap_or(0).write(writer)?;
                self.counterparty_htlc_minimum_msat.write(writer)?;
                self.holder_htlc_minimum_msat.write(writer)?;
                self.counterparty_max_accepted_htlcs.write(writer)?;
-               self.minimum_depth.write(writer)?;
+               self.minimum_depth.unwrap_or(0).write(writer)?;
 
                match &self.counterparty_forwarding_info {
                        Some(info) => {
@@ -4585,6 +4745,26 @@ impl<Signer: Sign> Writeable for Channel<Signer> {
                self.commitment_secrets.write(writer)?;
 
                self.channel_update_status.write(writer)?;
+
+               #[cfg(any(test, feature = "fuzztarget"))]
+               (self.historical_inbound_htlc_fulfills.len() as u64).write(writer)?;
+               #[cfg(any(test, feature = "fuzztarget"))]
+               for htlc in self.historical_inbound_htlc_fulfills.iter() {
+                       htlc.write(writer)?;
+               }
+
+               write_tlv_fields!(writer, {
+                       (0, self.announcement_sigs, option),
+                       // minimum_depth and counterparty_selected_channel_reserve_satoshis used to have a
+                       // default value instead of being Option<>al. Thus, to maintain compatibility we write
+                       // them twice, once with their original default values above, and once as an option
+                       // here. On the read side, old versions will simply ignore the odd-type entries here,
+                       // and new versions map the default values to None and allow the TLV entries here to
+                       // override that.
+                       (1, self.minimum_depth, option),
+                       (3, self.counterparty_selected_channel_reserve_satoshis, option),
+               });
+
                Ok(())
        }
 }
@@ -4593,11 +4773,7 @@ const MAX_ALLOC_SIZE: usize = 64*1024;
 impl<'a, Signer: Sign, K: Deref> ReadableArgs<&'a K> for Channel<Signer>
                where K::Target: KeysInterface<Signer = Signer> {
        fn read<R : ::std::io::Read>(reader: &mut R, keys_source: &'a K) -> Result<Self, DecodeError> {
-               let _ver: u8 = Readable::read(reader)?;
-               let min_ver: u8 = Readable::read(reader)?;
-               if min_ver > SERIALIZATION_VERSION {
-                       return Err(DecodeError::UnknownVersion);
-               }
+               let _ver = read_ver_prefix!(reader, SERIALIZATION_VERSION);
 
                let user_id = Readable::read(reader)?;
                let config: ChannelConfig = Readable::read(reader)?;
@@ -4730,11 +4906,21 @@ impl<'a, Signer: Sign, K: Deref> ReadableArgs<&'a K> for Channel<Signer>
                let counterparty_dust_limit_satoshis = Readable::read(reader)?;
                let holder_dust_limit_satoshis = Readable::read(reader)?;
                let counterparty_max_htlc_value_in_flight_msat = Readable::read(reader)?;
-               let counterparty_selected_channel_reserve_satoshis = Readable::read(reader)?;
+               let mut counterparty_selected_channel_reserve_satoshis = Some(Readable::read(reader)?);
+               if counterparty_selected_channel_reserve_satoshis == Some(0) {
+                       // Versions up to 0.0.98 had counterparty_selected_channel_reserve_satoshis as a
+                       // non-option, writing 0 for what we now consider None.
+                       counterparty_selected_channel_reserve_satoshis = None;
+               }
                let counterparty_htlc_minimum_msat = Readable::read(reader)?;
                let holder_htlc_minimum_msat = Readable::read(reader)?;
                let counterparty_max_accepted_htlcs = Readable::read(reader)?;
-               let minimum_depth = Readable::read(reader)?;
+               let mut minimum_depth = Some(Readable::read(reader)?);
+               if minimum_depth == Some(0) {
+                       // Versions up to 0.0.98 had minimum_depth as a non-option, writing 0 for what we now
+                       // consider None.
+                       minimum_depth = None;
+               }
 
                let counterparty_forwarding_info = match <u8 as Readable>::read(reader)? {
                        0 => None,
@@ -4759,6 +4945,23 @@ impl<'a, Signer: Sign, K: Deref> ReadableArgs<&'a K> for Channel<Signer>
 
                let channel_update_status = Readable::read(reader)?;
 
+               #[cfg(any(test, feature = "fuzztarget"))]
+               let mut historical_inbound_htlc_fulfills = HashSet::new();
+               #[cfg(any(test, feature = "fuzztarget"))]
+               {
+                       let htlc_fulfills_len: u64 = Readable::read(reader)?;
+                       for _ in 0..htlc_fulfills_len {
+                               assert!(historical_inbound_htlc_fulfills.insert(Readable::read(reader)?));
+                       }
+               }
+
+               let mut announcement_sigs = None;
+               read_tlv_fields!(reader, {
+                       (0, announcement_sigs, option),
+                       (1, minimum_depth, option),
+                       (3, counterparty_selected_channel_reserve_satoshis, option),
+               });
+
                let mut secp_ctx = Secp256k1::new();
                secp_ctx.seeded_randomize(&keys_source.get_secure_random_bytes());
 
@@ -4835,10 +5038,17 @@ impl<'a, Signer: Sign, K: Deref> ReadableArgs<&'a K> for Channel<Signer>
 
                        channel_update_status,
 
+                       announcement_sigs,
+
                        #[cfg(any(test, feature = "fuzztarget"))]
                        next_local_commitment_tx_fee_info_cached: Mutex::new(None),
                        #[cfg(any(test, feature = "fuzztarget"))]
                        next_remote_commitment_tx_fee_info_cached: Mutex::new(None),
+
+                       workaround_lnd_bug_4006: None,
+
+                       #[cfg(any(test, feature = "fuzztarget"))]
+                       historical_inbound_htlc_fulfills,
                })
        }
 }
@@ -4855,13 +5065,14 @@ mod tests {
        use bitcoin::hashes::hex::FromHex;
        use hex;
        use ln::{PaymentPreimage, PaymentHash};
-       use ln::channelmanager::{BestBlock, HTLCSource};
+       use ln::channelmanager::HTLCSource;
        use ln::channel::{Channel,InboundHTLCOutput,OutboundHTLCOutput,InboundHTLCState,OutboundHTLCState,HTLCOutputInCommitment,HTLCCandidate,HTLCInitiator,TxCreationKeys};
        use ln::channel::MAX_FUNDING_SATOSHIS;
        use ln::features::InitFeatures;
        use ln::msgs::{ChannelUpdate, DataLossProtect, DecodeError, OptionalField, UnsignedChannelUpdate};
        use ln::chan_utils;
        use ln::chan_utils::{ChannelPublicKeys, HolderCommitmentTransaction, CounterpartyChannelTransactionParameters, HTLC_SUCCESS_TX_WEIGHT, HTLC_TIMEOUT_TX_WEIGHT};
+       use chain::BestBlock;
        use chain::chaininterface::{FeeEstimator,ConfirmationTarget};
        use chain::keysinterface::{InMemorySigner, KeysInterface, BaseSign};
        use chain::transaction::OutPoint;
@@ -4877,6 +5088,7 @@ mod tests {
        use bitcoin::hashes::Hash;
        use bitcoin::hash_types::{Txid, WPubkeyHash};
        use std::sync::Arc;
+       use prelude::*;
 
        struct TestFeeEstimator {
                fee_est: u32
@@ -5207,6 +5419,7 @@ mod tests {
                config.channel_options.announced_channel = false;
                let mut chan = Channel::<InMemorySigner>::new_outbound(&&feeest, &&keys_provider, counterparty_node_id, 10_000_000, 100000, 42, &config).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
 
                let funding_info = OutPoint{ txid: Txid::from_hex("8984484a580b825b9972d7adb15050b3ab624ccd731946b3eeddb92f4e7ef6be").unwrap(), index: 0 };
 
@@ -5294,7 +5507,9 @@ mod tests {
                                        let remote_signature = Signature::from_der(&hex::decode($counterparty_htlc_sig_hex).unwrap()[..]).unwrap();
 
                                        let ref htlc = htlcs[$htlc_idx];
-                                       let htlc_tx = chan.build_htlc_transaction(&unsigned_tx.txid, &htlc, true, &keys, chan.feerate_per_kw);
+                                       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);
                                        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();