Remove one tab level when accessing a `peer_state`
[rust-lightning] / lightning / src / ln / channel.rs
index 55732d704febfcdd6c125c7af18411eb5ce07a3b..76dc15065c05cd298b532247de377b757ce5491f 100644 (file)
@@ -22,32 +22,33 @@ use bitcoin::secp256k1::{PublicKey,SecretKey};
 use bitcoin::secp256k1::{Secp256k1,ecdsa::Signature};
 use bitcoin::secp256k1;
 
-use ln::{PaymentPreimage, PaymentHash};
-use ln::features::{ChannelTypeFeatures, InitFeatures};
-use ln::msgs;
-use ln::msgs::{DecodeError, OptionalField, DataLossProtect};
-use ln::script::{self, ShutdownScript};
-use ln::channelmanager::{self, CounterpartyForwardingInfo, 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, ClosingTransaction};
-use ln::chan_utils;
-use chain::BestBlock;
-use chain::chaininterface::{FeeEstimator, ConfirmationTarget, LowerBoundedFeeEstimator};
-use chain::channelmonitor::{ChannelMonitor, ChannelMonitorUpdate, ChannelMonitorUpdateStep, LATENCY_GRACE_PERIOD_BLOCKS};
-use chain::transaction::{OutPoint, TransactionData};
-use chain::keysinterface::{Sign, KeysInterface};
-use util::events::ClosureReason;
-use util::ser::{Readable, ReadableArgs, Writeable, Writer, VecWriter};
-use util::logger::Logger;
-use util::errors::APIError;
-use util::config::{UserConfig, ChannelConfig, LegacyChannelConfig, ChannelHandshakeConfig, ChannelHandshakeLimits};
-use util::scid_utils::scid_from_parts;
-
-use io;
-use prelude::*;
+use crate::ln::{PaymentPreimage, PaymentHash};
+use crate::ln::features::{ChannelTypeFeatures, InitFeatures};
+use crate::ln::msgs;
+use crate::ln::msgs::{DecodeError, OptionalField, DataLossProtect};
+use crate::ln::script::{self, ShutdownScript};
+use crate::ln::channelmanager::{self, CounterpartyForwardingInfo, PendingHTLCStatus, HTLCSource, HTLCFailureMsg, PendingHTLCInfo, RAACommitmentOrder, BREAKDOWN_TIMEOUT, MIN_CLTV_EXPIRY_DELTA, MAX_LOCAL_BREAKDOWN_TIMEOUT};
+use crate::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, ClosingTransaction};
+use crate::ln::chan_utils;
+use crate::ln::onion_utils::HTLCFailReason;
+use crate::chain::BestBlock;
+use crate::chain::chaininterface::{FeeEstimator, ConfirmationTarget, LowerBoundedFeeEstimator};
+use crate::chain::channelmonitor::{ChannelMonitor, ChannelMonitorUpdate, ChannelMonitorUpdateStep, LATENCY_GRACE_PERIOD_BLOCKS};
+use crate::chain::transaction::{OutPoint, TransactionData};
+use crate::chain::keysinterface::{Sign, EntropySource, KeysInterface, BaseSign, SignerProvider};
+use crate::util::events::ClosureReason;
+use crate::util::ser::{Readable, ReadableArgs, Writeable, Writer, VecWriter};
+use crate::util::logger::Logger;
+use crate::util::errors::APIError;
+use crate::util::config::{UserConfig, ChannelConfig, LegacyChannelConfig, ChannelHandshakeConfig, ChannelHandshakeLimits};
+use crate::util::scid_utils::scid_from_parts;
+
+use crate::io;
+use crate::prelude::*;
 use core::{cmp,mem,fmt};
 use core::ops::Deref;
 #[cfg(any(test, fuzzing, debug_assertions))]
-use sync::Mutex;
+use crate::sync::Mutex;
 use bitcoin::hashes::hex::ToHex;
 
 #[cfg(test)]
@@ -244,9 +245,9 @@ enum HTLCUpdateAwaitingACK {
 /// There are a few "states" and then a number of flags which can be applied:
 /// We first move through init with OurInitSent -> TheirInitSent -> FundingCreated -> FundingSent.
 /// TheirChannelReady and OurChannelReady then get set on FundingSent, and when both are set we
-/// move on to ChannelFunded.
-/// Note that PeerDisconnected can be set on both ChannelFunded and FundingSent.
-/// ChannelFunded can then get all remaining flags set on it, until we finish shutdown, then we
+/// move on to ChannelReady.
+/// Note that PeerDisconnected can be set on both ChannelReady and FundingSent.
+/// ChannelReady can then get all remaining flags set on it, until we finish shutdown, then we
 /// move on to ShutdownComplete, at which point most calls into this channel are disallowed.
 enum ChannelState {
        /// Implies we have (or are prepared to) send our open_channel/accept_channel message
@@ -262,32 +263,32 @@ enum ChannelState {
        /// and our counterparty consider the funding transaction confirmed.
        FundingSent = 8,
        /// Flag which can be set on FundingSent to indicate they sent us a channel_ready message.
-       /// Once both TheirChannelReady and OurChannelReady are set, state moves on to ChannelFunded.
+       /// Once both TheirChannelReady and OurChannelReady are set, state moves on to ChannelReady.
        TheirChannelReady = 1 << 4,
        /// Flag which can be set on FundingSent to indicate we sent them a channel_ready message.
-       /// Once both TheirChannelReady and OurChannelReady are set, state moves on to ChannelFunded.
+       /// Once both TheirChannelReady and OurChannelReady are set, state moves on to ChannelReady.
        OurChannelReady = 1 << 5,
-       ChannelFunded = 64,
-       /// Flag which is set on ChannelFunded and FundingSent indicating remote side is considered
+       ChannelReady = 64,
+       /// Flag which is set on ChannelReady and FundingSent indicating remote side is considered
        /// "disconnected" and no updates are allowed until after we've done a channel_reestablish
        /// dance.
        PeerDisconnected = 1 << 7,
-       /// Flag which is set on ChannelFunded, FundingCreated, and FundingSent indicating the user has
-       /// told us they failed to update our ChannelMonitor somewhere and we should pause sending any
-       /// outbound messages until they've managed to do so.
-       MonitorUpdateFailed = 1 << 8,
+       /// Flag which is set on ChannelReady, FundingCreated, and FundingSent indicating the user has
+       /// told us a ChannelMonitor update is pending async persistence somewhere and we should pause
+       /// sending any outbound messages until they've managed to finish.
+       MonitorUpdateInProgress = 1 << 8,
        /// Flag which implies that we have sent a commitment_signed but are awaiting the responding
        /// revoke_and_ack message. During this time period, we can't generate new commitment_signed
        /// messages as then we will be unable to determine which HTLCs they included in their
        /// revoke_and_ack implicit ACK, so instead we have to hold them away temporarily to be sent
        /// later.
-       /// Flag is set on ChannelFunded.
+       /// Flag is set on ChannelReady.
        AwaitingRemoteRevoke = 1 << 9,
-       /// Flag which is set on ChannelFunded or FundingSent after receiving a shutdown message from
+       /// Flag which is set on ChannelReady or FundingSent after receiving a shutdown message from
        /// the remote end. If set, they may not add any new HTLCs to the channel, and we are expected
        /// to respond with our own shutdown message when possible.
        RemoteShutdownSent = 1 << 10,
-       /// Flag which is set on ChannelFunded or FundingSent after sending a shutdown message. At this
+       /// Flag which is set on ChannelReady or FundingSent after sending a shutdown message. At this
        /// point, we may not add any new HTLCs to the channel.
        LocalShutdownSent = 1 << 11,
        /// We've successfully negotiated a closing_signed dance. At this point ChannelManager is about
@@ -295,7 +296,7 @@ enum ChannelState {
        ShutdownComplete = 4096,
 }
 const BOTH_SIDES_SHUTDOWN_MASK: u32 = ChannelState::LocalShutdownSent as u32 | ChannelState::RemoteShutdownSent as u32;
-const MULTI_STATE_FLAGS: u32 = BOTH_SIDES_SHUTDOWN_MASK | ChannelState::PeerDisconnected as u32 | ChannelState::MonitorUpdateFailed as u32;
+const MULTI_STATE_FLAGS: u32 = BOTH_SIDES_SHUTDOWN_MASK | ChannelState::PeerDisconnected as u32 | ChannelState::MonitorUpdateInProgress as u32;
 
 pub const INITIAL_COMMITMENT_NUMBER: u64 = (1 << 48) - 1;
 
@@ -439,8 +440,6 @@ pub(super) struct ReestablishResponses {
        pub raa: Option<msgs::RevokeAndACK>,
        pub commitment_update: Option<msgs::CommitmentUpdate>,
        pub order: RAACommitmentOrder,
-       pub mon_update: Option<ChannelMonitorUpdate>,
-       pub holding_cell_failed_htlcs: Vec<(HTLCSource, PaymentHash)>,
        pub announcement_sigs: Option<msgs::AnnouncementSignatures>,
        pub shutdown_msg: Option<msgs::Shutdown>,
 }
@@ -509,7 +508,7 @@ pub(super) struct Channel<Signer: Sign> {
 
        inbound_handshake_limits_override: Option<ChannelHandshakeLimits>,
 
-       user_id: u64,
+       user_id: u128,
 
        channel_id: [u8; 32],
        channel_state: u32,
@@ -736,6 +735,13 @@ pub(super) struct Channel<Signer: Sign> {
        // don't currently support node id aliases and eventually privacy should be provided with
        // blinded paths instead of simple scid+node_id aliases.
        outbound_scid_alias: u64,
+
+       // We track whether we already emitted a `ChannelReady` event.
+       channel_ready_event_emitted: bool,
+
+       /// The unique identifier used to re-derive the private key material for the channel through
+       /// [`SignerProvider::derive_channel_signer`].
+       channel_keys_id: [u8; 32],
 }
 
 #[cfg(any(test, fuzzing))]
@@ -899,7 +905,7 @@ impl<Signer: Sign> Channel<Signer> {
        // Constructors:
        pub fn new_outbound<K: Deref, F: Deref>(
                fee_estimator: &LowerBoundedFeeEstimator<F>, keys_provider: &K, counterparty_node_id: PublicKey, their_features: &InitFeatures,
-               channel_value_satoshis: u64, push_msat: u64, user_id: u64, config: &UserConfig, current_chain_height: u32,
+               channel_value_satoshis: u64, push_msat: u64, user_id: u128, config: &UserConfig, current_chain_height: u32,
                outbound_scid_alias: u64
        ) -> Result<Channel<Signer>, APIError>
        where K::Target: KeysInterface<Signer = Signer>,
@@ -908,7 +914,8 @@ impl<Signer: Sign> Channel<Signer> {
                let opt_anchors = false; // TODO - should be based on features
 
                let holder_selected_contest_delay = config.channel_handshake_config.our_to_self_delay;
-               let holder_signer = keys_provider.get_channel_signer(false, channel_value_satoshis);
+               let channel_keys_id = keys_provider.generate_channel_keys_id(false, channel_value_satoshis, user_id);
+               let holder_signer = keys_provider.derive_channel_signer(channel_value_satoshis, channel_keys_id);
                let pubkeys = holder_signer.pubkeys().clone();
 
                if !their_features.supports_wumbo() && channel_value_satoshis > MAX_FUNDING_SATOSHIS_NO_WUMBO {
@@ -1037,6 +1044,7 @@ impl<Signer: Sign> Channel<Signer> {
                                counterparty_parameters: None,
                                funding_outpoint: None,
                                opt_anchors: if opt_anchors { Some(()) } else { None },
+                               opt_non_zero_fee_anchors: None
                        },
                        funding_transaction: None,
 
@@ -1063,15 +1071,19 @@ impl<Signer: Sign> Channel<Signer> {
                        latest_inbound_scid_alias: None,
                        outbound_scid_alias,
 
+                       channel_ready_event_emitted: false,
+
                        #[cfg(any(test, fuzzing))]
                        historical_inbound_htlc_fulfills: HashSet::new(),
 
                        channel_type: Self::get_initial_channel_type(&config),
+                       channel_keys_id,
                })
        }
 
-       fn check_remote_fee<F: Deref>(fee_estimator: &LowerBoundedFeeEstimator<F>, feerate_per_kw: u32) -> Result<(), ChannelError>
-               where F::Target: FeeEstimator
+       fn check_remote_fee<F: Deref, L: Deref>(fee_estimator: &LowerBoundedFeeEstimator<F>,
+               feerate_per_kw: u32, cur_feerate_per_kw: Option<u32>, logger: &L)
+               -> Result<(), ChannelError> where F::Target: FeeEstimator, L::Target: Logger,
        {
                // We only bound the fee updates on the upper side to prevent completely absurd feerates,
                // always accepting up to 25 sat/vByte or 10x our fee estimator's "High Priority" fee.
@@ -1088,6 +1100,14 @@ impl<Signer: Sign> Channel<Signer> {
                // of 1.1 sat/vbyte and a receiver that wants 1.1 rounded up to 2. Thus, we always add 250
                // sat/kw before the comparison here.
                if feerate_per_kw + 250 < lower_limit {
+                       if let Some(cur_feerate) = cur_feerate_per_kw {
+                               if feerate_per_kw > cur_feerate {
+                                       log_warn!(logger,
+                                               "Accepting feerate that may prevent us from closing this channel because it's higher than what we have now. Had {} s/kW, now {} s/kW.",
+                                               cur_feerate, feerate_per_kw);
+                                       return Ok(());
+                               }
+                       }
                        return Err(ChannelError::Close(format!("Peer's feerate much too low. Actual: {}. Our expected lower limit: {} (- 250)", feerate_per_kw, lower_limit)));
                }
                Ok(())
@@ -1097,7 +1117,7 @@ impl<Signer: Sign> Channel<Signer> {
        /// Assumes chain_hash has already been checked and corresponds with what we expect!
        pub fn new_from_req<K: Deref, F: Deref, L: Deref>(
                fee_estimator: &LowerBoundedFeeEstimator<F>, keys_provider: &K, counterparty_node_id: PublicKey, their_features: &InitFeatures,
-               msg: &msgs::OpenChannel, user_id: u64, config: &UserConfig, current_chain_height: u32, logger: &L,
+               msg: &msgs::OpenChannel, user_id: u128, config: &UserConfig, current_chain_height: u32, logger: &L,
                outbound_scid_alias: u64
        ) -> Result<Channel<Signer>, ChannelError>
                where K::Target: KeysInterface<Signer = Signer>,
@@ -1140,7 +1160,8 @@ impl<Signer: Sign> Channel<Signer> {
                        return Err(ChannelError::Close("Channel Type was not understood - we require static remote key".to_owned()));
                }
 
-               let holder_signer = keys_provider.get_channel_signer(true, msg.funding_satoshis);
+               let channel_keys_id = keys_provider.generate_channel_keys_id(true, msg.funding_satoshis, user_id);
+               let holder_signer = keys_provider.derive_channel_signer(msg.funding_satoshis, channel_keys_id);
                let pubkeys = holder_signer.pubkeys().clone();
                let counterparty_pubkeys = ChannelPublicKeys {
                        funding_pubkey: msg.funding_pubkey,
@@ -1174,7 +1195,7 @@ impl<Signer: Sign> Channel<Signer> {
                if msg.htlc_minimum_msat >= full_channel_value_msat {
                        return Err(ChannelError::Close(format!("Minimum htlc value ({}) was larger than full channel value ({})", msg.htlc_minimum_msat, full_channel_value_msat)));
                }
-               Channel::<Signer>::check_remote_fee(fee_estimator, msg.feerate_per_kw)?;
+               Channel::<Signer>::check_remote_fee(fee_estimator, msg.feerate_per_kw, None, logger)?;
 
                let max_counterparty_selected_contest_delay = u16::min(config.channel_handshake_limits.their_to_self_delay, MAX_LOCAL_BREAKDOWN_TIMEOUT);
                if msg.to_self_delay > max_counterparty_selected_contest_delay {
@@ -1371,6 +1392,7 @@ impl<Signer: Sign> Channel<Signer> {
                                }),
                                funding_outpoint: None,
                                opt_anchors: if opt_anchors { Some(()) } else { None },
+                               opt_non_zero_fee_anchors: None
                        },
                        funding_transaction: None,
 
@@ -1397,10 +1419,13 @@ impl<Signer: Sign> Channel<Signer> {
                        latest_inbound_scid_alias: None,
                        outbound_scid_alias,
 
+                       channel_ready_event_emitted: false,
+
                        #[cfg(any(test, fuzzing))]
                        historical_inbound_htlc_fulfills: HashSet::new(),
 
                        channel_type,
+                       channel_keys_id,
                };
 
                Ok(chan)
@@ -1733,27 +1758,27 @@ impl<Signer: Sign> Channel<Signer> {
        /// our counterparty!)
        /// The result is a transaction which we can revoke broadcastership of (ie a "local" transaction)
        /// TODO Some magic rust shit to compile-time check this?
-       fn build_holder_transaction_keys(&self, commitment_number: u64) -> Result<TxCreationKeys, ChannelError> {
+       fn build_holder_transaction_keys(&self, commitment_number: u64) -> TxCreationKeys {
                let per_commitment_point = self.holder_signer.get_per_commitment_point(commitment_number, &self.secp_ctx);
                let delayed_payment_base = &self.get_holder_pubkeys().delayed_payment_basepoint;
                let htlc_basepoint = &self.get_holder_pubkeys().htlc_basepoint;
                let counterparty_pubkeys = self.get_counterparty_pubkeys();
 
-               Ok(secp_check!(TxCreationKeys::derive_new(&self.secp_ctx, &per_commitment_point, delayed_payment_base, htlc_basepoint, &counterparty_pubkeys.revocation_basepoint, &counterparty_pubkeys.htlc_basepoint), "Local tx keys generation got bogus keys".to_owned()))
+               TxCreationKeys::derive_new(&self.secp_ctx, &per_commitment_point, delayed_payment_base, htlc_basepoint, &counterparty_pubkeys.revocation_basepoint, &counterparty_pubkeys.htlc_basepoint)
        }
 
        #[inline]
        /// Creates a set of keys for build_commitment_transaction to generate a transaction which we
        /// will sign and send to our counterparty.
        /// If an Err is returned, it is a ChannelError::Close (for get_outbound_funding_created)
-       fn build_remote_transaction_keys(&self) -> Result<TxCreationKeys, ChannelError> {
+       fn build_remote_transaction_keys(&self) -> TxCreationKeys {
                //TODO: Ensure that the payment_key derived here ends up in the library users' wallet as we
                //may see payments to it!
                let revocation_basepoint = &self.get_holder_pubkeys().revocation_basepoint;
                let htlc_basepoint = &self.get_holder_pubkeys().htlc_basepoint;
                let counterparty_pubkeys = self.get_counterparty_pubkeys();
 
-               Ok(secp_check!(TxCreationKeys::derive_new(&self.secp_ctx, &self.counterparty_cur_commitment_point.unwrap(), &counterparty_pubkeys.delayed_payment_basepoint, &counterparty_pubkeys.htlc_basepoint, revocation_basepoint, htlc_basepoint), "Remote tx keys generation got bogus keys".to_owned()))
+               TxCreationKeys::derive_new(&self.secp_ctx, &self.counterparty_cur_commitment_point.unwrap(), &counterparty_pubkeys.delayed_payment_basepoint, &counterparty_pubkeys.htlc_basepoint, revocation_basepoint, htlc_basepoint)
        }
 
        /// Gets the redeemscript for the funding transaction output (ie the funding transaction output
@@ -1776,7 +1801,7 @@ impl<Signer: Sign> Channel<Signer> {
        where L::Target: Logger {
                // Assert that we'll add the HTLC claim to the holding cell in `get_update_fulfill_htlc`
                // (see equivalent if condition there).
-               assert!(self.channel_state & (ChannelState::AwaitingRemoteRevoke as u32 | ChannelState::PeerDisconnected as u32 | ChannelState::MonitorUpdateFailed as u32) != 0);
+               assert!(self.channel_state & (ChannelState::AwaitingRemoteRevoke as u32 | ChannelState::PeerDisconnected as u32 | ChannelState::MonitorUpdateInProgress as u32) != 0);
                let mon_update_id = self.latest_monitor_update_id; // Forget the ChannelMonitor update
                let fulfill_resp = self.get_update_fulfill_htlc(htlc_id_arg, payment_preimage_arg, logger);
                self.latest_monitor_update_id = mon_update_id;
@@ -1786,11 +1811,11 @@ impl<Signer: Sign> Channel<Signer> {
        }
 
        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
+               // Either ChannelReady 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,
                // either.
-               if (self.channel_state & (ChannelState::ChannelFunded as u32)) != (ChannelState::ChannelFunded as u32) {
+               if (self.channel_state & (ChannelState::ChannelReady as u32)) != (ChannelState::ChannelReady as u32) {
                        panic!("Was asked to fulfill an HTLC when channel was not in an operational state");
                }
                assert_eq!(self.channel_state & ChannelState::ShutdownComplete as u32, 0);
@@ -1846,7 +1871,7 @@ impl<Signer: Sign> Channel<Signer> {
                        }],
                };
 
-               if (self.channel_state & (ChannelState::AwaitingRemoteRevoke as u32 | ChannelState::PeerDisconnected as u32 | ChannelState::MonitorUpdateFailed as u32)) != 0 {
+               if (self.channel_state & (ChannelState::AwaitingRemoteRevoke as u32 | ChannelState::PeerDisconnected as u32 | ChannelState::MonitorUpdateInProgress as u32)) != 0 {
                        // Note that this condition is the same as the assertion in
                        // `claim_htlc_while_disconnected_dropping_mon_update` and must match exactly -
                        // `claim_htlc_while_disconnected_dropping_mon_update` would not work correctly if we
@@ -1930,10 +1955,27 @@ impl<Signer: Sign> Channel<Signer> {
        /// 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) {
+       ///
+       /// If we do fail twice, we `debug_assert!(false)` and return `Ok(None)`. Thus, this will always
+       /// return `Ok(_)` if preconditions are met. In any case, `Err`s will only be
+       /// [`ChannelError::Ignore`].
+       pub fn queue_fail_htlc<L: Deref>(&mut self, htlc_id_arg: u64, err_packet: msgs::OnionErrorPacket, logger: &L)
+       -> Result<(), ChannelError> where L::Target: Logger {
+               self.fail_htlc(htlc_id_arg, err_packet, true, logger)
+                       .map(|msg_opt| assert!(msg_opt.is_none(), "We forced holding cell?"))
+       }
+
+       /// 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, this will always
+       /// return `Ok(_)` if preconditions are met. In any case, `Err`s will only be
+       /// [`ChannelError::Ignore`].
+       fn fail_htlc<L: Deref>(&mut self, htlc_id_arg: u64, err_packet: msgs::OnionErrorPacket, mut force_holding_cell: bool, logger: &L)
+       -> Result<Option<msgs::UpdateFailHTLC>, ChannelError> where L::Target: Logger {
+               if (self.channel_state & (ChannelState::ChannelReady as u32)) != (ChannelState::ChannelReady as u32) {
                        panic!("Was asked to fail an HTLC when channel was not in an operational state");
                }
                assert_eq!(self.channel_state & ChannelState::ShutdownComplete as u32, 0);
@@ -1970,8 +2012,13 @@ impl<Signer: Sign> Channel<Signer> {
                        return Ok(None);
                }
 
+               if (self.channel_state & (ChannelState::AwaitingRemoteRevoke as u32 | ChannelState::PeerDisconnected as u32 | ChannelState::MonitorUpdateInProgress as u32)) != 0 {
+                       debug_assert!(force_holding_cell, "!force_holding_cell is only called when emptying the holding cell, so we shouldn't end up back in it!");
+                       force_holding_cell = true;
+               }
+
                // Now update local state:
-               if (self.channel_state & (ChannelState::AwaitingRemoteRevoke as u32 | ChannelState::PeerDisconnected as u32 | ChannelState::MonitorUpdateFailed as u32)) != 0 {
+               if force_holding_cell {
                        for pending_update in self.holding_cell_htlc_updates.iter() {
                                match pending_update {
                                        &HTLCUpdateAwaitingACK::ClaimHTLC { htlc_id, .. } => {
@@ -2141,7 +2188,7 @@ impl<Signer: Sign> Channel<Signer> {
        fn funding_created_signature<L: Deref>(&mut self, sig: &Signature, logger: &L) -> Result<(Txid, CommitmentTransaction, Signature), ChannelError> where L::Target: Logger {
                let funding_script = self.get_funding_redeemscript();
 
-               let keys = self.build_holder_transaction_keys(self.cur_holder_commitment_transaction_number)?;
+               let keys = self.build_holder_transaction_keys(self.cur_holder_commitment_transaction_number);
                let initial_commitment_tx = self.build_commitment_transaction(self.cur_holder_commitment_transaction_number, &keys, true, false, logger).tx;
                {
                        let trusted_tx = initial_commitment_tx.trust();
@@ -2155,7 +2202,7 @@ impl<Signer: Sign> Channel<Signer> {
                        secp_check!(self.secp_ctx.verify_ecdsa(&sighash, &sig, self.counterparty_funding_pubkey()), "Invalid funding_created signature from peer".to_owned());
                }
 
-               let counterparty_keys = self.build_remote_transaction_keys()?;
+               let counterparty_keys = self.build_remote_transaction_keys();
                let counterparty_initial_commitment_tx = self.build_commitment_transaction(self.cur_counterparty_commitment_transaction_number, &counterparty_keys, false, false, logger).tx;
 
                let counterparty_trusted_tx = counterparty_initial_commitment_tx.trust();
@@ -2174,7 +2221,13 @@ impl<Signer: Sign> Channel<Signer> {
                &self.get_counterparty_pubkeys().funding_pubkey
        }
 
-       pub fn funding_created<L: Deref>(&mut self, msg: &msgs::FundingCreated, best_block: BestBlock, logger: &L) -> Result<(msgs::FundingSigned, ChannelMonitor<Signer>, Option<msgs::ChannelReady>), ChannelError> where L::Target: Logger {
+       pub fn funding_created<K: Deref, L: Deref>(
+               &mut self, msg: &msgs::FundingCreated, best_block: BestBlock, keys_source: &K, logger: &L
+       ) -> Result<(msgs::FundingSigned, ChannelMonitor<<K::Target as SignerProvider>::Signer>, Option<msgs::ChannelReady>), ChannelError>
+       where
+               K::Target: KeysInterface,
+               L::Target: Logger
+       {
                if self.is_outbound() {
                        return Err(ChannelError::Close("Received funding_created for an outbound channel?".to_owned()));
                }
@@ -2197,7 +2250,7 @@ impl<Signer: Sign> Channel<Signer> {
                self.channel_transaction_parameters.funding_outpoint = Some(funding_txo);
                // This is an externally observable change before we finish all our checks.  In particular
                // funding_created_signature may fail.
-               self.holder_signer.ready_channel(&self.channel_transaction_parameters);
+               self.holder_signer.provide_channel_parameters(&self.channel_transaction_parameters);
 
                let (counterparty_initial_commitment_txid, initial_commitment_tx, signature) = match self.funding_created_signature(&msg.signature, logger) {
                        Ok(res) => res,
@@ -2229,7 +2282,9 @@ impl<Signer: Sign> Channel<Signer> {
                let funding_txo_script = funding_redeemscript.to_v0_p2wsh();
                let obscure_factor = get_commitment_transaction_number_obscure_factor(&self.get_holder_pubkeys().payment_point, &self.get_counterparty_pubkeys().payment_point, self.is_outbound());
                let shutdown_script = self.shutdown_scriptpubkey.clone().map(|script| script.into_inner());
-               let channel_monitor = ChannelMonitor::new(self.secp_ctx.clone(), self.holder_signer.clone(),
+               let mut monitor_signer = keys_source.derive_channel_signer(self.channel_value_satoshis, self.channel_keys_id);
+               monitor_signer.provide_channel_parameters(&self.channel_transaction_parameters);
+               let channel_monitor = ChannelMonitor::new(self.secp_ctx.clone(), monitor_signer,
                                                          shutdown_script, self.get_holder_selected_contest_delay(),
                                                          &self.destination_script, (funding_txo, funding_txo_script.clone()),
                                                          &self.channel_transaction_parameters,
@@ -2254,11 +2309,17 @@ impl<Signer: Sign> Channel<Signer> {
 
        /// Handles a funding_signed message from the remote end.
        /// If this call is successful, broadcast the funding transaction (and not before!)
-       pub fn funding_signed<L: Deref>(&mut self, msg: &msgs::FundingSigned, best_block: BestBlock, logger: &L) -> Result<(ChannelMonitor<Signer>, Transaction, Option<msgs::ChannelReady>), ChannelError> where L::Target: Logger {
+       pub fn funding_signed<K: Deref, L: Deref>(
+               &mut self, msg: &msgs::FundingSigned, best_block: BestBlock, keys_source: &K, logger: &L
+       ) -> Result<(ChannelMonitor<<K::Target as SignerProvider>::Signer>, Transaction, Option<msgs::ChannelReady>), ChannelError>
+       where
+               K::Target: KeysInterface,
+               L::Target: Logger
+       {
                if !self.is_outbound() {
                        return Err(ChannelError::Close("Received funding_signed for an inbound channel?".to_owned()));
                }
-               if self.channel_state & !(ChannelState::MonitorUpdateFailed as u32) != ChannelState::FundingCreated as u32 {
+               if self.channel_state & !(ChannelState::MonitorUpdateInProgress as u32) != ChannelState::FundingCreated as u32 {
                        return Err(ChannelError::Close("Received funding_signed in strange state!".to_owned()));
                }
                if self.commitment_secrets.get_min_seen_secret() != (1 << 48) ||
@@ -2269,7 +2330,7 @@ impl<Signer: Sign> Channel<Signer> {
 
                let funding_script = self.get_funding_redeemscript();
 
-               let counterparty_keys = self.build_remote_transaction_keys()?;
+               let counterparty_keys = self.build_remote_transaction_keys();
                let counterparty_initial_commitment_tx = self.build_commitment_transaction(self.cur_counterparty_commitment_transaction_number, &counterparty_keys, false, false, logger).tx;
                let counterparty_trusted_tx = counterparty_initial_commitment_tx.trust();
                let counterparty_initial_bitcoin_tx = counterparty_trusted_tx.built_transaction();
@@ -2277,7 +2338,7 @@ impl<Signer: Sign> Channel<Signer> {
                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 holder_signer = self.build_holder_transaction_keys(self.cur_holder_commitment_transaction_number);
                let initial_commitment_tx = self.build_commitment_transaction(self.cur_holder_commitment_transaction_number, &holder_signer, true, false, logger).tx;
                {
                        let trusted_tx = initial_commitment_tx.trust();
@@ -2306,7 +2367,9 @@ impl<Signer: Sign> Channel<Signer> {
                let funding_txo_script = funding_redeemscript.to_v0_p2wsh();
                let obscure_factor = get_commitment_transaction_number_obscure_factor(&self.get_holder_pubkeys().payment_point, &self.get_counterparty_pubkeys().payment_point, self.is_outbound());
                let shutdown_script = self.shutdown_scriptpubkey.clone().map(|script| script.into_inner());
-               let channel_monitor = ChannelMonitor::new(self.secp_ctx.clone(), self.holder_signer.clone(),
+               let mut monitor_signer = keys_source.derive_channel_signer(self.channel_value_satoshis, self.channel_keys_id);
+               monitor_signer.provide_channel_parameters(&self.channel_transaction_parameters);
+               let channel_monitor = ChannelMonitor::new(self.secp_ctx.clone(), monitor_signer,
                                                          shutdown_script, self.get_holder_selected_contest_delay(),
                                                          &self.destination_script, (funding_txo, funding_txo_script),
                                                          &self.channel_transaction_parameters,
@@ -2316,7 +2379,7 @@ impl<Signer: Sign> Channel<Signer> {
 
                channel_monitor.provide_latest_counterparty_commitment_tx(counterparty_initial_bitcoin_tx.txid, Vec::new(), self.cur_counterparty_commitment_transaction_number, self.counterparty_cur_commitment_point.unwrap(), logger);
 
-               assert_eq!(self.channel_state & (ChannelState::MonitorUpdateFailed as u32), 0); // We have no had any monitor(s) yet to fail update!
+               assert_eq!(self.channel_state & (ChannelState::MonitorUpdateInProgress as u32), 0); // We have no had any monitor(s) yet to fail update!
                self.channel_state = ChannelState::FundingSent as u32;
                self.cur_holder_commitment_transaction_number -= 1;
                self.cur_counterparty_commitment_transaction_number -= 1;
@@ -2349,9 +2412,9 @@ impl<Signer: Sign> Channel<Signer> {
                if non_shutdown_state == ChannelState::FundingSent as u32 {
                        self.channel_state |= ChannelState::TheirChannelReady as u32;
                } else if non_shutdown_state == (ChannelState::FundingSent as u32 | ChannelState::OurChannelReady as u32) {
-                       self.channel_state = ChannelState::ChannelFunded as u32 | (self.channel_state & MULTI_STATE_FLAGS);
+                       self.channel_state = ChannelState::ChannelReady as u32 | (self.channel_state & MULTI_STATE_FLAGS);
                        self.update_time_counter += 1;
-               } else if self.channel_state & (ChannelState::ChannelFunded as u32) != 0 ||
+               } else if self.channel_state & (ChannelState::ChannelReady as u32) != 0 ||
                        // If we reconnected before sending our `channel_ready` they may still resend theirs:
                        (self.channel_state & (ChannelState::FundingSent as u32 | ChannelState::TheirChannelReady as u32) ==
                                              (ChannelState::FundingSent as u32 | ChannelState::TheirChannelReady as u32))
@@ -2712,12 +2775,12 @@ impl<Signer: Sign> Channel<Signer> {
        pub fn update_add_htlc<F, L: Deref>(&mut self, msg: &msgs::UpdateAddHTLC, mut pending_forward_status: PendingHTLCStatus, create_pending_htlc_status: F, logger: &L) -> Result<(), ChannelError>
        where F: for<'a> Fn(&'a Self, PendingHTLCStatus, u16) -> PendingHTLCStatus, L::Target: Logger {
                // We can't accept HTLCs sent after we've sent a shutdown.
-               let local_sent_shutdown = (self.channel_state & (ChannelState::ChannelFunded as u32 | ChannelState::LocalShutdownSent as u32)) != (ChannelState::ChannelFunded as u32);
+               let local_sent_shutdown = (self.channel_state & (ChannelState::ChannelReady as u32 | ChannelState::LocalShutdownSent as u32)) != (ChannelState::ChannelReady as u32);
                if local_sent_shutdown {
                        pending_forward_status = create_pending_htlc_status(self, pending_forward_status, 0x4000|8);
                }
                // If the remote has sent a shutdown prior to adding this HTLC, then they are in violation of the spec.
-               let remote_sent_shutdown = (self.channel_state & (ChannelState::ChannelFunded as u32 | ChannelState::RemoteShutdownSent as u32)) != (ChannelState::ChannelFunded as u32);
+               let remote_sent_shutdown = (self.channel_state & (ChannelState::ChannelReady as u32 | ChannelState::RemoteShutdownSent as u32)) != (ChannelState::ChannelReady as u32);
                if remote_sent_shutdown {
                        return Err(ChannelError::Close("Got add HTLC message when channel was not in an operational state".to_owned()));
                }
@@ -2894,7 +2957,7 @@ impl<Signer: Sign> Channel<Signer> {
        }
 
        pub fn update_fulfill_htlc(&mut self, msg: &msgs::UpdateFulfillHTLC) -> Result<(HTLCSource, u64), ChannelError> {
-               if (self.channel_state & (ChannelState::ChannelFunded as u32)) != (ChannelState::ChannelFunded as u32) {
+               if (self.channel_state & (ChannelState::ChannelReady as u32)) != (ChannelState::ChannelReady as u32) {
                        return Err(ChannelError::Close("Got fulfill HTLC message when channel was not in an operational state".to_owned()));
                }
                if self.channel_state & (ChannelState::PeerDisconnected as u32) == ChannelState::PeerDisconnected as u32 {
@@ -2905,7 +2968,7 @@ impl<Signer: Sign> Channel<Signer> {
        }
 
        pub fn update_fail_htlc(&mut self, msg: &msgs::UpdateFailHTLC, fail_reason: HTLCFailReason) -> Result<(), ChannelError> {
-               if (self.channel_state & (ChannelState::ChannelFunded as u32)) != (ChannelState::ChannelFunded as u32) {
+               if (self.channel_state & (ChannelState::ChannelReady as u32)) != (ChannelState::ChannelReady as u32) {
                        return Err(ChannelError::Close("Got fail HTLC message when channel was not in an operational state".to_owned()));
                }
                if self.channel_state & (ChannelState::PeerDisconnected as u32) == ChannelState::PeerDisconnected as u32 {
@@ -2917,7 +2980,7 @@ impl<Signer: Sign> Channel<Signer> {
        }
 
        pub fn update_fail_malformed_htlc(&mut self, msg: &msgs::UpdateFailMalformedHTLC, fail_reason: HTLCFailReason) -> Result<(), ChannelError> {
-               if (self.channel_state & (ChannelState::ChannelFunded as u32)) != (ChannelState::ChannelFunded as u32) {
+               if (self.channel_state & (ChannelState::ChannelReady as u32)) != (ChannelState::ChannelReady as u32) {
                        return Err(ChannelError::Close("Got fail malformed HTLC message when channel was not in an operational state".to_owned()));
                }
                if self.channel_state & (ChannelState::PeerDisconnected as u32) == ChannelState::PeerDisconnected as u32 {
@@ -2931,7 +2994,7 @@ impl<Signer: Sign> Channel<Signer> {
        pub fn commitment_signed<L: Deref>(&mut self, msg: &msgs::CommitmentSigned, logger: &L) -> Result<(msgs::RevokeAndACK, Option<msgs::CommitmentSigned>, ChannelMonitorUpdate), (Option<ChannelMonitorUpdate>, ChannelError)>
                where L::Target: Logger
        {
-               if (self.channel_state & (ChannelState::ChannelFunded as u32)) != (ChannelState::ChannelFunded as u32) {
+               if (self.channel_state & (ChannelState::ChannelReady as u32)) != (ChannelState::ChannelReady as u32) {
                        return Err((None, ChannelError::Close("Got commitment signed message when channel was not in an operational state".to_owned())));
                }
                if self.channel_state & (ChannelState::PeerDisconnected as u32) == ChannelState::PeerDisconnected as u32 {
@@ -2943,7 +3006,7 @@ impl<Signer: Sign> Channel<Signer> {
 
                let funding_script = self.get_funding_redeemscript();
 
-               let keys = self.build_holder_transaction_keys(self.cur_holder_commitment_transaction_number).map_err(|e| (None, e))?;
+               let keys = self.build_holder_transaction_keys(self.cur_holder_commitment_transaction_number);
 
                let commitment_stats = self.build_commitment_transaction(self.cur_holder_commitment_transaction_number, &keys, true, false, logger);
                let commitment_txid = {
@@ -3002,7 +3065,7 @@ impl<Signer: Sign> Channel<Signer> {
                        if let Some(_) = htlc.transaction_output_index {
                                let htlc_tx = chan_utils::build_htlc_transaction(&commitment_txid, commitment_stats.feerate_per_kw,
                                        self.get_counterparty_selected_contest_delay().unwrap(), &htlc, self.opt_anchors(),
-                                       &keys.broadcaster_delayed_payment_key, &keys.revocation_key);
+                                       false, &keys.broadcaster_delayed_payment_key, &keys.revocation_key);
 
                                let htlc_redeemscript = chan_utils::get_htlc_redeemscript(&htlc, self.opt_anchors(), &keys);
                                let htlc_sighashtype = if self.opt_anchors() { EcdsaSighashType::SinglePlusAnyoneCanPay } else { EcdsaSighashType::All };
@@ -3078,7 +3141,7 @@ impl<Signer: Sign> Channel<Signer> {
                // send_commitment_no_status_check() next which will reset this to RAAFirst.
                self.resend_order = RAACommitmentOrder::CommitmentFirst;
 
-               if (self.channel_state & ChannelState::MonitorUpdateFailed as u32) != 0 {
+               if (self.channel_state & ChannelState::MonitorUpdateInProgress as u32) != 0 {
                        // In case we initially failed monitor updating without requiring a response, we need
                        // to make sure the RAA gets sent first.
                        self.monitor_pending_revoke_and_ack = true;
@@ -3124,16 +3187,16 @@ impl<Signer: Sign> Channel<Signer> {
        /// 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 {
+               if self.channel_state >= ChannelState::ChannelReady as u32 &&
+                  (self.channel_state & (ChannelState::AwaitingRemoteRevoke as u32 | ChannelState::PeerDisconnected as u32 | ChannelState::MonitorUpdateInProgress 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)
+       /// Frees any pending commitment updates in the holding cell, generating the relevant messages
+       /// for our counterparty.
        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);
+               assert_eq!(self.channel_state & ChannelState::MonitorUpdateInProgress 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{} 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()));
@@ -3157,7 +3220,7 @@ impl<Signer: Sign> Channel<Signer> {
                                // to rebalance channels.
                                match &htlc_update {
                                        &HTLCUpdateAwaitingACK::AddHTLC {amount_msat, cltv_expiry, ref payment_hash, ref source, ref onion_routing_packet, ..} => {
-                                               match self.send_htlc(amount_msat, *payment_hash, cltv_expiry, source.clone(), onion_routing_packet.clone(), logger) {
+                                               match self.send_htlc(amount_msat, *payment_hash, cltv_expiry, source.clone(), onion_routing_packet.clone(), false, logger) {
                                                        Ok(update_add_msg_option) => update_add_htlcs.push(update_add_msg_option.unwrap()),
                                                        Err(e) => {
                                                                match e {
@@ -3193,13 +3256,13 @@ impl<Signer: Sign> Channel<Signer> {
                                                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(), logger) {
+                                               match self.fail_htlc(htlc_id, err_packet.clone(), false, 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.
+                                                               // `queue_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) => {
@@ -3216,7 +3279,7 @@ impl<Signer: Sign> Channel<Signer> {
                                return Ok((None, htlcs_to_fail));
                        }
                        let update_fee = if let Some(feerate) = self.holding_cell_update_fee.take() {
-                               self.send_update_fee(feerate, logger)
+                               self.send_update_fee(feerate, false, logger)
                        } else {
                                None
                        };
@@ -3252,7 +3315,7 @@ impl<Signer: Sign> Channel<Signer> {
        pub fn revoke_and_ack<L: Deref>(&mut self, msg: &msgs::RevokeAndACK, logger: &L) -> Result<RAAUpdates, ChannelError>
                where L::Target: Logger,
        {
-               if (self.channel_state & (ChannelState::ChannelFunded as u32)) != (ChannelState::ChannelFunded as u32) {
+               if (self.channel_state & (ChannelState::ChannelReady as u32)) != (ChannelState::ChannelReady as u32) {
                        return Err(ChannelError::Close("Got revoke/ACK message when channel was not in an operational state".to_owned()));
                }
                if self.channel_state & (ChannelState::PeerDisconnected as u32) == ChannelState::PeerDisconnected as u32 {
@@ -3428,7 +3491,7 @@ impl<Signer: Sign> Channel<Signer> {
                        }
                }
 
-               if (self.channel_state & ChannelState::MonitorUpdateFailed as u32) == ChannelState::MonitorUpdateFailed as u32 {
+               if (self.channel_state & ChannelState::MonitorUpdateInProgress as u32) == ChannelState::MonitorUpdateInProgress as u32 {
                        // We can't actually generate a new commitment transaction (incl by freeing holding
                        // cells) while we can't update the monitor, so we just return what we have.
                        if require_commitment {
@@ -3516,12 +3579,22 @@ impl<Signer: Sign> Channel<Signer> {
                }
        }
 
+       /// Queues up an outbound update fee by placing it in the holding cell. You should call
+       /// [`Self::maybe_free_holding_cell_htlcs`] in order to actually generate and send the
+       /// commitment update.
+       pub fn queue_update_fee<L: Deref>(&mut self, feerate_per_kw: u32, logger: &L) where L::Target: Logger {
+               let msg_opt = self.send_update_fee(feerate_per_kw, true, logger);
+               assert!(msg_opt.is_none(), "We forced holding cell?");
+       }
+
        /// Adds a pending update to this channel. See the doc for send_htlc for
        /// further details on the optionness of the return value.
        /// If our balance is too low to cover the cost of the next commitment transaction at the
        /// new feerate, the update is cancelled.
-       /// You MUST call send_commitment prior to any other calls on this Channel
-       fn send_update_fee<L: Deref>(&mut self, feerate_per_kw: u32, logger: &L) -> Option<msgs::UpdateFee> where L::Target: Logger {
+       ///
+       /// You MUST call [`Self::send_commitment_no_state_update`] prior to any other calls on this
+       /// [`Channel`] if `force_holding_cell` is false.
+       fn send_update_fee<L: Deref>(&mut self, feerate_per_kw: u32, mut force_holding_cell: bool, logger: &L) -> Option<msgs::UpdateFee> where L::Target: Logger {
                if !self.is_outbound() {
                        panic!("Cannot send fee from inbound channel");
                }
@@ -3535,7 +3608,7 @@ impl<Signer: Sign> Channel<Signer> {
                // Before proposing a feerate update, check that we can actually afford the new fee.
                let inbound_stats = self.get_inbound_pending_htlc_stats(Some(feerate_per_kw));
                let outbound_stats = self.get_outbound_pending_htlc_stats(Some(feerate_per_kw));
-               let keys = if let Ok(keys) = self.build_holder_transaction_keys(self.cur_holder_commitment_transaction_number) { keys } else { return None; };
+               let keys = self.build_holder_transaction_keys(self.cur_holder_commitment_transaction_number);
                let commitment_stats = self.build_commitment_transaction(self.cur_holder_commitment_transaction_number, &keys, true, true, logger);
                let buffer_fee_msat = Channel::<Signer>::commit_tx_fee_sat(feerate_per_kw, commitment_stats.num_nondust_htlcs + outbound_stats.on_holder_tx_holding_cell_htlcs_count as usize + CONCURRENT_INBOUND_HTLC_FEE_BUFFER as usize, self.opt_anchors()) * 1000;
                let holder_balance_msat = commitment_stats.local_balance_msat - outbound_stats.holding_cell_msat;
@@ -3557,7 +3630,11 @@ impl<Signer: Sign> Channel<Signer> {
                        return None;
                }
 
-               if (self.channel_state & (ChannelState::AwaitingRemoteRevoke as u32 | ChannelState::MonitorUpdateFailed as u32)) != 0 {
+               if (self.channel_state & (ChannelState::AwaitingRemoteRevoke as u32 | ChannelState::MonitorUpdateInProgress as u32)) != 0 {
+                       force_holding_cell = true;
+               }
+
+               if force_holding_cell {
                        self.holding_cell_update_fee = Some(feerate_per_kw);
                        return None;
                }
@@ -3571,16 +3648,6 @@ impl<Signer: Sign> Channel<Signer> {
                })
        }
 
-       pub fn send_update_fee_and_commit<L: Deref>(&mut self, feerate_per_kw: u32, logger: &L) -> Result<Option<(msgs::UpdateFee, msgs::CommitmentSigned, ChannelMonitorUpdate)>, ChannelError> where L::Target: Logger {
-               match self.send_update_fee(feerate_per_kw, logger) {
-                       Some(update_fee) => {
-                               let (commitment_signed, monitor_update) = self.send_commitment_no_status_check(logger)?;
-                               Ok(Some((update_fee, commitment_signed, monitor_update)))
-                       },
-                       None => Ok(None)
-               }
-       }
-
        /// 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.
@@ -3677,15 +3744,15 @@ impl<Signer: Sign> Channel<Signer> {
                self.monitor_pending_forwards.append(&mut pending_forwards);
                self.monitor_pending_failures.append(&mut pending_fails);
                self.monitor_pending_finalized_fulfills.append(&mut pending_finalized_claimed_htlcs);
-               self.channel_state |= ChannelState::MonitorUpdateFailed as u32;
+               self.channel_state |= ChannelState::MonitorUpdateInProgress as u32;
        }
 
        /// Indicates that the latest ChannelMonitor update has been committed by the client
        /// successfully and we should restore normal operation. Returns messages which should be sent
        /// to the remote side.
        pub fn monitor_updating_restored<L: Deref>(&mut self, logger: &L, node_pk: PublicKey, genesis_block_hash: BlockHash, best_block_height: u32) -> MonitorRestoreUpdates where L::Target: Logger {
-               assert_eq!(self.channel_state & ChannelState::MonitorUpdateFailed as u32, ChannelState::MonitorUpdateFailed as u32);
-               self.channel_state &= !(ChannelState::MonitorUpdateFailed as u32);
+               assert_eq!(self.channel_state & ChannelState::MonitorUpdateInProgress as u32, ChannelState::MonitorUpdateInProgress as u32);
+               self.channel_state &= !(ChannelState::MonitorUpdateInProgress as u32);
 
                // If we're past (or at) the FundingSent stage on an outbound channel, try to
                // (re-)broadcast the funding transaction as we may have declined to broadcast it when we
@@ -3696,13 +3763,13 @@ impl<Signer: Sign> Channel<Signer> {
                        } else { None };
                // That said, if the funding transaction is already confirmed (ie we're active with a
                // minimum_depth over 0) don't bother re-broadcasting the confirmed funding tx.
-               if self.channel_state & !MULTI_STATE_FLAGS >= ChannelState::ChannelFunded as u32 && self.minimum_depth != Some(0) {
+               if self.channel_state & !MULTI_STATE_FLAGS >= ChannelState::ChannelReady as u32 && self.minimum_depth != Some(0) {
                        funding_broadcastable = None;
                }
 
-               // We will never broadcast the funding transaction when we're in MonitorUpdateFailed (and
-               // we assume the user never directly broadcasts the funding transaction and waits for us to
-               // do it). Thus, we can only ever hit monitor_pending_channel_ready when we're
+               // We will never broadcast the funding transaction when we're in MonitorUpdateInProgress
+               // (and we assume the user never directly broadcasts the funding transaction and waits for
+               // us to do it). Thus, we can only ever hit monitor_pending_channel_ready when we're
                // * an inbound channel that failed to persist the monitor on funding_created and we got
                //   the funding transaction confirmed before the monitor was persisted, or
                // * a 0-conf channel and intended to send the channel_ready before any broadcast at all.
@@ -3755,8 +3822,8 @@ impl<Signer: Sign> Channel<Signer> {
                }
        }
 
-       pub fn update_fee<F: Deref>(&mut self, fee_estimator: &LowerBoundedFeeEstimator<F>, msg: &msgs::UpdateFee) -> Result<(), ChannelError>
-               where F::Target: FeeEstimator
+       pub fn update_fee<F: Deref, L: Deref>(&mut self, fee_estimator: &LowerBoundedFeeEstimator<F>, msg: &msgs::UpdateFee, logger: &L) -> Result<(), ChannelError>
+               where F::Target: FeeEstimator, L::Target: Logger
        {
                if self.is_outbound() {
                        return Err(ChannelError::Close("Non-funding remote tried to update channel fee".to_owned()));
@@ -3764,7 +3831,7 @@ impl<Signer: Sign> Channel<Signer> {
                if self.channel_state & (ChannelState::PeerDisconnected as u32) == ChannelState::PeerDisconnected as u32 {
                        return Err(ChannelError::Close("Peer sent update_fee when we needed a channel_reestablish".to_owned()));
                }
-               Channel::<Signer>::check_remote_fee(fee_estimator, msg.feerate_per_kw)?;
+               Channel::<Signer>::check_remote_fee(fee_estimator, msg.feerate_per_kw, Some(self.feerate_per_kw), logger)?;
                let feerate_over_dust_buffer = msg.feerate_per_kw > self.get_dust_buffer_feerate(None);
 
                self.pending_update_fee = Some((msg.feerate_per_kw, FeeUpdateState::RemoteAnnounced));
@@ -3941,16 +4008,15 @@ impl<Signer: Sign> Channel<Signer> {
                if self.channel_state & (ChannelState::FundingSent as u32) == ChannelState::FundingSent as u32 {
                        // If we're waiting on a monitor update, we shouldn't re-send any channel_ready's.
                        if self.channel_state & (ChannelState::OurChannelReady as u32) == 0 ||
-                                       self.channel_state & (ChannelState::MonitorUpdateFailed as u32) != 0 {
+                                       self.channel_state & (ChannelState::MonitorUpdateInProgress as u32) != 0 {
                                if msg.next_remote_commitment_number != 0 {
                                        return Err(ChannelError::Close("Peer claimed they saw a revoke_and_ack but we haven't sent channel_ready yet".to_owned()));
                                }
                                // Short circuit the whole handler as there is nothing we can resend them
                                return Ok(ReestablishResponses {
                                        channel_ready: None,
-                                       raa: None, commitment_update: None, mon_update: None,
+                                       raa: None, commitment_update: None,
                                        order: RAACommitmentOrder::CommitmentFirst,
-                                       holding_cell_failed_htlcs: Vec::new(),
                                        shutdown_msg, announcement_sigs,
                                });
                        }
@@ -3963,9 +4029,8 @@ impl<Signer: Sign> Channel<Signer> {
                                        next_per_commitment_point,
                                        short_channel_id_alias: Some(self.outbound_scid_alias),
                                }),
-                               raa: None, commitment_update: None, mon_update: None,
+                               raa: None, commitment_update: None,
                                order: RAACommitmentOrder::CommitmentFirst,
-                               holding_cell_failed_htlcs: Vec::new(),
                                shutdown_msg, announcement_sigs,
                        });
                }
@@ -3975,7 +4040,7 @@ impl<Signer: Sign> Channel<Signer> {
                        // Note that if we need to repeat our ChannelReady we'll do that in the next if block.
                        None
                } else if msg.next_remote_commitment_number + 1 == (INITIAL_COMMITMENT_NUMBER - 1) - self.cur_holder_commitment_transaction_number {
-                       if self.channel_state & (ChannelState::MonitorUpdateFailed as u32) != 0 {
+                       if self.channel_state & (ChannelState::MonitorUpdateInProgress as u32) != 0 {
                                self.monitor_pending_revoke_and_ack = true;
                                None
                        } else {
@@ -3992,7 +4057,7 @@ impl<Signer: Sign> Channel<Signer> {
                let next_counterparty_commitment_number = INITIAL_COMMITMENT_NUMBER - self.cur_counterparty_commitment_transaction_number + if (self.channel_state & ChannelState::AwaitingRemoteRevoke as u32) != 0 { 1 } else { 0 };
 
                let channel_ready = if msg.next_local_commitment_number == 1 && INITIAL_COMMITMENT_NUMBER - self.cur_holder_commitment_transaction_number == 1 {
-                       // We should never have to worry about MonitorUpdateFailed resending ChannelReady
+                       // We should never have to worry about MonitorUpdateInProgress resending ChannelReady
                        let next_per_commitment_point = self.holder_signer.get_per_commitment_point(self.cur_holder_commitment_transaction_number, &self.secp_ctx);
                        Some(msgs::ChannelReady {
                                channel_id: self.channel_id(),
@@ -4008,46 +4073,12 @@ impl<Signer: Sign> Channel<Signer> {
                                log_debug!(logger, "Reconnected channel {} with no loss", log_bytes!(self.channel_id()));
                        }
 
-                       if (self.channel_state & (ChannelState::AwaitingRemoteRevoke as u32 | ChannelState::MonitorUpdateFailed as u32)) == 0 {
-                               // 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
-                               // now!
-                               match self.free_holding_cell_htlcs(logger) {
-                                       Err(ChannelError::Close(msg)) => Err(ChannelError::Close(msg)),
-                                       Err(ChannelError::Warn(_)) | Err(ChannelError::Ignore(_)) =>
-                                               panic!("Got non-channel-failing result from free_holding_cell_htlcs"),
-                                       Ok((Some((commitment_update, monitor_update)), holding_cell_failed_htlcs)) => {
-                                               Ok(ReestablishResponses {
-                                                       channel_ready, shutdown_msg, announcement_sigs,
-                                                       raa: required_revoke,
-                                                       commitment_update: Some(commitment_update),
-                                                       order: self.resend_order.clone(),
-                                                       mon_update: Some(monitor_update),
-                                                       holding_cell_failed_htlcs,
-                                               })
-                                       },
-                                       Ok((None, holding_cell_failed_htlcs)) => {
-                                               Ok(ReestablishResponses {
-                                                       channel_ready, shutdown_msg, announcement_sigs,
-                                                       raa: required_revoke,
-                                                       commitment_update: None,
-                                                       order: self.resend_order.clone(),
-                                                       mon_update: None,
-                                                       holding_cell_failed_htlcs,
-                                               })
-                                       },
-                               }
-                       } else {
-                               Ok(ReestablishResponses {
-                                       channel_ready, shutdown_msg, announcement_sigs,
-                                       raa: required_revoke,
-                                       commitment_update: None,
-                                       order: self.resend_order.clone(),
-                                       mon_update: None,
-                                       holding_cell_failed_htlcs: Vec::new(),
-                               })
-                       }
+                       Ok(ReestablishResponses {
+                               channel_ready, shutdown_msg, announcement_sigs,
+                               raa: required_revoke,
+                               commitment_update: None,
+                               order: self.resend_order.clone(),
+                       })
                } else if msg.next_local_commitment_number == next_counterparty_commitment_number - 1 {
                        if required_revoke.is_some() {
                                log_debug!(logger, "Reconnected channel {} with lost outbound RAA and lost remote commitment tx", log_bytes!(self.channel_id()));
@@ -4055,13 +4086,12 @@ impl<Signer: Sign> Channel<Signer> {
                                log_debug!(logger, "Reconnected channel {} with only lost remote commitment tx", log_bytes!(self.channel_id()));
                        }
 
-                       if self.channel_state & (ChannelState::MonitorUpdateFailed as u32) != 0 {
+                       if self.channel_state & (ChannelState::MonitorUpdateInProgress as u32) != 0 {
                                self.monitor_pending_commitment_signed = true;
                                Ok(ReestablishResponses {
                                        channel_ready, shutdown_msg, announcement_sigs,
-                                       commitment_update: None, raa: None, mon_update: None,
+                                       commitment_update: None, raa: None,
                                        order: self.resend_order.clone(),
-                                       holding_cell_failed_htlcs: Vec::new(),
                                })
                        } else {
                                Ok(ReestablishResponses {
@@ -4069,8 +4099,6 @@ impl<Signer: Sign> Channel<Signer> {
                                        raa: required_revoke,
                                        commitment_update: Some(self.get_last_commitment_update(logger)),
                                        order: self.resend_order.clone(),
-                                       mon_update: None,
-                                       holding_cell_failed_htlcs: Vec::new(),
                                })
                        }
                } else {
@@ -4137,7 +4165,7 @@ impl<Signer: Sign> Channel<Signer> {
                self.pending_inbound_htlcs.is_empty() && self.pending_outbound_htlcs.is_empty() &&
                        self.channel_state &
                                (BOTH_SIDES_SHUTDOWN_MASK | ChannelState::AwaitingRemoteRevoke as u32 |
-                                ChannelState::PeerDisconnected as u32 | ChannelState::MonitorUpdateFailed as u32)
+                                ChannelState::PeerDisconnected as u32 | ChannelState::MonitorUpdateInProgress as u32)
                                == BOTH_SIDES_SHUTDOWN_MASK &&
                        self.pending_update_fee.is_none()
        }
@@ -4198,7 +4226,7 @@ impl<Signer: Sign> Channel<Signer> {
        pub fn shutdown<K: Deref>(
                &mut self, keys_provider: &K, their_features: &InitFeatures, msg: &msgs::Shutdown
        ) -> Result<(Option<msgs::Shutdown>, Option<ChannelMonitorUpdate>, Vec<(HTLCSource, PaymentHash)>), ChannelError>
-       where K::Target: KeysInterface<Signer = Signer>
+       where K::Target: KeysInterface
        {
                if self.channel_state & (ChannelState::PeerDisconnected as u32) == ChannelState::PeerDisconnected as u32 {
                        return Err(ChannelError::Close("Peer sent shutdown when we needed a channel_reestablish".to_owned()));
@@ -4333,7 +4361,7 @@ impl<Signer: Sign> Channel<Signer> {
                        return Err(ChannelError::Close("Remote tried to send a closing_signed when we were supposed to propose the first one".to_owned()));
                }
 
-               if self.channel_state & ChannelState::MonitorUpdateFailed as u32 != 0 {
+               if self.channel_state & ChannelState::MonitorUpdateInProgress as u32 != 0 {
                        self.pending_counterparty_closing_signed = Some(msg.clone());
                        return Ok((None, None));
                }
@@ -4475,7 +4503,7 @@ impl<Signer: Sign> Channel<Signer> {
 
        /// 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 {
+       pub fn get_user_id(&self) -> u128 {
                self.user_id
        }
 
@@ -4513,6 +4541,21 @@ impl<Signer: Sign> Channel<Signer> {
                self.channel_transaction_parameters.funding_outpoint
        }
 
+       /// Returns the block hash in which our funding transaction was confirmed.
+       pub fn get_funding_tx_confirmed_in(&self) -> Option<BlockHash> {
+               self.funding_tx_confirmed_in
+       }
+
+       /// Returns the current number of confirmations on the funding transaction.
+       pub fn get_funding_tx_confirmations(&self, height: u32) -> u32 {
+               if self.funding_tx_confirmation_height == 0 {
+                       // We either haven't seen any confirmation yet, or observed a reorg.
+                       return 0;
+               }
+
+               height.checked_sub(self.funding_tx_confirmation_height).map_or(0, |c| c + 1)
+       }
+
        fn get_holder_selected_contest_delay(&self) -> u16 {
                self.channel_transaction_parameters.holder_selected_contest_delay
        }
@@ -4598,6 +4641,16 @@ impl<Signer: Sign> Channel<Signer> {
                self.prev_config.map(|prev_config| prev_config.0)
        }
 
+       // Checks whether we should emit a `ChannelReady` event.
+       pub(crate) fn should_emit_channel_ready_event(&mut self) -> bool {
+               self.is_usable() && !self.channel_ready_event_emitted
+       }
+
+       // Remembers that we already emitted a `ChannelReady` event.
+       pub(crate) fn set_channel_ready_event_emitted(&mut self) {
+               self.channel_ready_event_emitted = true;
+       }
+
        /// Tracks the number of ticks elapsed since the previous [`ChannelConfig`] was updated. Once
        /// [`EXPIRE_PREV_CONFIG_TICKS`] is reached, the previous config is considered expired and will
        /// no longer be considered when forwarding HTLCs.
@@ -4766,8 +4819,8 @@ impl<Signer: Sign> Channel<Signer> {
        /// Returns true if this channel is fully established and not known to be closing.
        /// Allowed in any state (including after shutdown)
        pub fn is_usable(&self) -> bool {
-               let mask = ChannelState::ChannelFunded as u32 | BOTH_SIDES_SHUTDOWN_MASK;
-               (self.channel_state & mask) == (ChannelState::ChannelFunded as u32) && !self.monitor_pending_channel_ready
+               let mask = ChannelState::ChannelReady as u32 | BOTH_SIDES_SHUTDOWN_MASK;
+               (self.channel_state & mask) == (ChannelState::ChannelReady as u32) && !self.monitor_pending_channel_ready
        }
 
        /// Returns true if this channel is currently available for use. This is a superset of
@@ -4780,7 +4833,7 @@ impl<Signer: Sign> Channel<Signer> {
        /// Returns true if this channel has been marked as awaiting a monitor update to move forward.
        /// Allowed in any state (including after shutdown)
        pub fn is_awaiting_monitor_update(&self) -> bool {
-               (self.channel_state & ChannelState::MonitorUpdateFailed as u32) != 0
+               (self.channel_state & ChannelState::MonitorUpdateInProgress as u32) != 0
        }
 
        /// Returns true if funding_created was sent/received.
@@ -4795,7 +4848,7 @@ impl<Signer: Sign> Channel<Signer> {
        pub fn is_awaiting_initial_mon_persist(&self) -> bool {
                if !self.is_awaiting_monitor_update() { return false; }
                if self.channel_state &
-                       !(ChannelState::TheirChannelReady as u32 | ChannelState::PeerDisconnected as u32 | ChannelState::MonitorUpdateFailed as u32)
+                       !(ChannelState::TheirChannelReady as u32 | ChannelState::PeerDisconnected as u32 | ChannelState::MonitorUpdateInProgress as u32)
                                == ChannelState::FundingSent as u32 {
                        // If we're not a 0conf channel, we'll be waiting on a monitor update with only
                        // FundingSent set, though our peer could have sent their channel_ready.
@@ -4826,7 +4879,7 @@ impl<Signer: Sign> Channel<Signer> {
 
        /// Returns true if our channel_ready has been sent
        pub fn is_our_channel_ready(&self) -> bool {
-               (self.channel_state & ChannelState::OurChannelReady as u32) != 0 || self.channel_state >= ChannelState::ChannelFunded as u32
+               (self.channel_state & ChannelState::OurChannelReady as u32) != 0 || self.channel_state >= ChannelState::ChannelReady as u32
        }
 
        /// Returns true if our peer has either initiated or agreed to shut down the channel.
@@ -4880,14 +4933,14 @@ impl<Signer: Sign> Channel<Signer> {
                        self.channel_state |= ChannelState::OurChannelReady as u32;
                        true
                } else if non_shutdown_state == (ChannelState::FundingSent as u32 | ChannelState::TheirChannelReady as u32) {
-                       self.channel_state = ChannelState::ChannelFunded as u32 | (self.channel_state & MULTI_STATE_FLAGS);
+                       self.channel_state = ChannelState::ChannelReady as u32 | (self.channel_state & MULTI_STATE_FLAGS);
                        self.update_time_counter += 1;
                        true
                } else if non_shutdown_state == (ChannelState::FundingSent as u32 | ChannelState::OurChannelReady as u32) {
                        // We got a reorg but not enough to trigger a force close, just ignore.
                        false
                } else {
-                       if self.funding_tx_confirmation_height != 0 && self.channel_state < ChannelState::ChannelFunded as u32 {
+                       if self.funding_tx_confirmation_height != 0 && self.channel_state < ChannelState::ChannelReady as u32 {
                                // We should never see a funding transaction on-chain until we've received
                                // funding_signed (if we're an outbound channel), or seen funding_generated (if we're
                                // an inbound channel - before that we have no known funding TXID). The fuzzer,
@@ -4902,7 +4955,7 @@ impl<Signer: Sign> Channel<Signer> {
                };
 
                if need_commitment_update {
-                       if self.channel_state & (ChannelState::MonitorUpdateFailed as u32) == 0 {
+                       if self.channel_state & (ChannelState::MonitorUpdateInProgress as u32) == 0 {
                                if self.channel_state & (ChannelState::PeerDisconnected as u32) == 0 {
                                        let next_per_commitment_point =
                                                self.holder_signer.get_per_commitment_point(INITIAL_COMMITMENT_NUMBER - 1, &self.secp_ctx);
@@ -5031,7 +5084,7 @@ impl<Signer: Sign> Channel<Signer> {
                }
 
                let non_shutdown_state = self.channel_state & (!MULTI_STATE_FLAGS);
-               if non_shutdown_state >= ChannelState::ChannelFunded as u32 ||
+               if non_shutdown_state >= ChannelState::ChannelReady as u32 ||
                   (non_shutdown_state & ChannelState::OurChannelReady as u32) == ChannelState::OurChannelReady as u32 {
                        let mut funding_tx_confirmations = height as i64 - self.funding_tx_confirmation_height as i64 + 1;
                        if self.funding_tx_confirmation_height == 0 {
@@ -5059,7 +5112,7 @@ impl<Signer: Sign> Channel<Signer> {
                                height >= self.channel_creation_height + FUNDING_CONF_DEADLINE_BLOCKS {
                        log_info!(logger, "Closing channel {} due to funding timeout", log_bytes!(self.channel_id));
                        // If funding_tx_confirmed_in is unset, the channel must not be active
-                       assert!(non_shutdown_state <= ChannelState::ChannelFunded as u32);
+                       assert!(non_shutdown_state <= ChannelState::ChannelReady as u32);
                        assert_eq!(non_shutdown_state & ChannelState::OurChannelReady as u32, 0);
                        return Err(ClosureReason::FundingTimedOut);
                }
@@ -5156,7 +5209,7 @@ impl<Signer: Sign> Channel<Signer> {
        /// should be sent back to the counterparty node.
        ///
        /// [`msgs::AcceptChannel`]: crate::ln::msgs::AcceptChannel
-       pub fn accept_inbound_channel(&mut self, user_id: u64) -> msgs::AcceptChannel {
+       pub fn accept_inbound_channel(&mut self, user_id: u128) -> msgs::AcceptChannel {
                if self.is_outbound() {
                        panic!("Tried to send accept_channel for an outbound channel?");
                }
@@ -5219,7 +5272,7 @@ impl<Signer: Sign> Channel<Signer> {
 
        /// If an Err is returned, it is a ChannelError::Close (for get_outbound_funding_created)
        fn get_outbound_funding_created_signature<L: Deref>(&mut self, logger: &L) -> Result<Signature, ChannelError> where L::Target: Logger {
-               let counterparty_keys = self.build_remote_transaction_keys()?;
+               let counterparty_keys = self.build_remote_transaction_keys();
                let counterparty_initial_commitment_tx = self.build_commitment_transaction(self.cur_counterparty_commitment_transaction_number, &counterparty_keys, false, false, logger).tx;
                Ok(self.holder_signer.sign_counterparty_commitment(&counterparty_initial_commitment_tx, Vec::new(), &self.secp_ctx)
                                .map_err(|_| ChannelError::Close("Failed to get signatures for new commitment_signed".to_owned()))?.0)
@@ -5246,7 +5299,7 @@ impl<Signer: Sign> Channel<Signer> {
                }
 
                self.channel_transaction_parameters.funding_outpoint = Some(funding_txo);
-               self.holder_signer.ready_channel(&self.channel_transaction_parameters);
+               self.holder_signer.provide_channel_parameters(&self.channel_transaction_parameters);
 
                let signature = match self.get_outbound_funding_created_signature(logger) {
                        Ok(res) => res,
@@ -5468,23 +5521,44 @@ impl<Signer: Sign> Channel<Signer> {
 
        // Send stuff to our remote peers:
 
+       /// Queues up an outbound HTLC to send by placing it in the holding cell. You should call
+       /// [`Self::maybe_free_holding_cell_htlcs`] in order to actually generate and send the
+       /// commitment update.
+       ///
+       /// `Err`s will only be [`ChannelError::Ignore`].
+       pub fn queue_add_htlc<L: Deref>(&mut self, amount_msat: u64, payment_hash: PaymentHash, cltv_expiry: u32, source: HTLCSource,
+               onion_routing_packet: msgs::OnionPacket, logger: &L)
+       -> Result<(), ChannelError> where L::Target: Logger {
+               self
+                       .send_htlc(amount_msat, payment_hash, cltv_expiry, source, onion_routing_packet, true, logger)
+                       .map(|msg_opt| assert!(msg_opt.is_none(), "We forced holding cell?"))
+                       .map_err(|err| {
+                               if let ChannelError::Ignore(_) = err { /* fine */ }
+                               else { debug_assert!(false, "Queueing cannot trigger channel failure"); }
+                               err
+                       })
+       }
+
        /// 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.
+       /// [`Self::send_htlc_and_commit`] instead cause you'll want both messages at once.
        ///
        /// 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.
+       /// * In cases where we're marked MonitorUpdateInProgress, 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!
+       /// You MUST call [`Self::send_commitment_no_state_update`] prior to calling any other methods
+       /// on this [`Channel`] if `force_holding_cell` is false.
        ///
-       /// If an Err is returned, it's a ChannelError::Ignore!
-       pub fn send_htlc<L: Deref>(&mut self, amount_msat: u64, payment_hash: PaymentHash, cltv_expiry: u32, source: HTLCSource, onion_routing_packet: msgs::OnionPacket, logger: &L) -> Result<Option<msgs::UpdateAddHTLC>, ChannelError> where L::Target: Logger {
-               if (self.channel_state & (ChannelState::ChannelFunded as u32 | BOTH_SIDES_SHUTDOWN_MASK)) != (ChannelState::ChannelFunded as u32) {
+       /// `Err`s will only be [`ChannelError::Ignore`].
+       fn send_htlc<L: Deref>(&mut self, amount_msat: u64, payment_hash: PaymentHash, cltv_expiry: u32, source: HTLCSource,
+               onion_routing_packet: msgs::OnionPacket, mut force_holding_cell: bool, logger: &L)
+       -> Result<Option<msgs::UpdateAddHTLC>, ChannelError> where L::Target: Logger {
+               if (self.channel_state & (ChannelState::ChannelReady as u32 | BOTH_SIDES_SHUTDOWN_MASK)) != (ChannelState::ChannelReady as u32) {
                        return Err(ChannelError::Ignore("Cannot send HTLC until channel is fully established and we haven't started shutting down".to_owned()));
                }
                let channel_total_msat = self.channel_value_satoshis * 1000;
@@ -5520,7 +5594,7 @@ impl<Signer: Sign> Channel<Signer> {
                        return Err(ChannelError::Ignore(format!("Cannot send value that would put us over the max HTLC value in flight our peer will accept ({})", self.counterparty_max_htlc_value_in_flight_msat)));
                }
 
-               let keys = self.build_holder_transaction_keys(self.cur_holder_commitment_transaction_number)?;
+               let keys = self.build_holder_transaction_keys(self.cur_holder_commitment_transaction_number);
                let commitment_stats = self.build_commitment_transaction(self.cur_holder_commitment_transaction_number, &keys, true, true, logger);
                if !self.is_outbound() {
                        // Check that we won't violate the remote channel reserve by adding this HTLC.
@@ -5578,8 +5652,12 @@ impl<Signer: Sign> Channel<Signer> {
                        return Err(ChannelError::Ignore(format!("Cannot send value that would put our balance under counterparty-announced channel reserve value ({})", chan_reserve_msat)));
                }
 
+               if (self.channel_state & (ChannelState::AwaitingRemoteRevoke as u32 | ChannelState::MonitorUpdateInProgress as u32)) != 0 {
+                       force_holding_cell = true;
+               }
+
                // Now update local state:
-               if (self.channel_state & (ChannelState::AwaitingRemoteRevoke as u32 | ChannelState::MonitorUpdateFailed as u32)) != 0 {
+               if force_holding_cell {
                        self.holding_cell_htlc_updates.push(HTLCUpdateAwaitingACK::AddHTLC {
                                amount_msat,
                                payment_hash,
@@ -5612,41 +5690,6 @@ impl<Signer: Sign> Channel<Signer> {
                Ok(Some(res))
        }
 
-       /// Creates a signed commitment transaction to send to the remote peer.
-       /// Always returns a ChannelError::Close if an immediately-preceding (read: the
-       /// last call to this Channel) send_htlc returned Ok(Some(_)) and there is an Err.
-       /// May panic if called except immediately after a successful, Ok(Some(_))-returning send_htlc.
-       pub fn send_commitment<L: Deref>(&mut self, logger: &L) -> Result<(msgs::CommitmentSigned, ChannelMonitorUpdate), ChannelError> where L::Target: Logger {
-               if (self.channel_state & (ChannelState::ChannelFunded as u32)) != (ChannelState::ChannelFunded as u32) {
-                       panic!("Cannot create commitment tx until channel is fully established");
-               }
-               if (self.channel_state & (ChannelState::AwaitingRemoteRevoke as u32)) == (ChannelState::AwaitingRemoteRevoke as u32) {
-                       panic!("Cannot create commitment tx until remote revokes their previous commitment");
-               }
-               if (self.channel_state & (ChannelState::PeerDisconnected as u32)) == (ChannelState::PeerDisconnected as u32) {
-                       panic!("Cannot create commitment tx while disconnected, as send_htlc will have returned an Err so a send_commitment precondition has been violated");
-               }
-               if (self.channel_state & (ChannelState::MonitorUpdateFailed as u32)) == (ChannelState::MonitorUpdateFailed as u32) {
-                       panic!("Cannot create commitment tx while awaiting monitor update unfreeze, as send_htlc will have returned an Err so a send_commitment precondition has been violated");
-               }
-               let mut have_updates = self.is_outbound() && self.pending_update_fee.is_some();
-               for htlc in self.pending_outbound_htlcs.iter() {
-                       if let OutboundHTLCState::LocalAnnounced(_) = htlc.state {
-                               have_updates = true;
-                       }
-                       if have_updates { break; }
-               }
-               for htlc in self.pending_inbound_htlcs.iter() {
-                       if let InboundHTLCState::LocalRemoved(_) = htlc.state {
-                               have_updates = true;
-                       }
-                       if have_updates { break; }
-               }
-               if !have_updates {
-                       panic!("Cannot create commitment tx until we have some updates to send");
-               }
-               self.send_commitment_no_status_check(logger)
-       }
        /// Only fails in case of bad keys
        fn send_commitment_no_status_check<L: Deref>(&mut self, logger: &L) -> Result<(msgs::CommitmentSigned, ChannelMonitorUpdate), ChannelError> where L::Target: Logger {
                log_trace!(logger, "Updating HTLC state for a newly-sent commitment_signed...");
@@ -5712,7 +5755,7 @@ impl<Signer: Sign> Channel<Signer> {
        /// Only fails in case of bad keys. Used for channel_reestablish commitment_signed generation
        /// when we shouldn't change HTLC/channel state.
        fn send_commitment_no_state_update<L: Deref>(&self, logger: &L) -> Result<(msgs::CommitmentSigned, (Txid, Vec<(HTLCOutputInCommitment, Option<&HTLCSource>)>)), ChannelError> where L::Target: Logger {
-               let counterparty_keys = self.build_remote_transaction_keys()?;
+               let counterparty_keys = self.build_remote_transaction_keys();
                let commitment_stats = self.build_commitment_transaction(self.cur_counterparty_commitment_transaction_number, &counterparty_keys, false, true, logger);
                let counterparty_commitment_txid = commitment_stats.tx.trust().txid();
                let (signature, htlc_signatures);
@@ -5753,7 +5796,7 @@ impl<Signer: Sign> Channel<Signer> {
 
                        for (ref htlc_sig, ref htlc) in htlc_signatures.iter().zip(htlcs) {
                                log_trace!(logger, "Signed remote HTLC tx {} with redeemscript {} with pubkey {} -> {} in channel {}",
-                                       encode::serialize_hex(&chan_utils::build_htlc_transaction(&counterparty_commitment_txid, commitment_stats.feerate_per_kw, self.get_holder_selected_contest_delay(), htlc, self.opt_anchors(), &counterparty_keys.broadcaster_delayed_payment_key, &counterparty_keys.revocation_key)),
+                                       encode::serialize_hex(&chan_utils::build_htlc_transaction(&counterparty_commitment_txid, commitment_stats.feerate_per_kw, self.get_holder_selected_contest_delay(), htlc, self.opt_anchors(), false, &counterparty_keys.broadcaster_delayed_payment_key, &counterparty_keys.revocation_key)),
                                        encode::serialize_hex(&chan_utils::get_htlc_redeemscript(&htlc, self.opt_anchors(), &counterparty_keys)),
                                        log_bytes!(counterparty_keys.broadcaster_htlc_key.serialize()),
                                        log_bytes!(htlc_sig.serialize_compact()[..]), log_bytes!(self.channel_id()));
@@ -5769,10 +5812,11 @@ impl<Signer: Sign> Channel<Signer> {
 
        /// Adds a pending outbound HTLC to this channel, and creates a signed commitment transaction
        /// to send to the remote peer in one go.
-       /// Shorthand for calling send_htlc() followed by send_commitment(), see docs on those for
-       /// more info.
+       ///
+       /// Shorthand for calling [`Self::send_htlc`] followed by a commitment update, see docs on
+       /// [`Self::send_htlc`] and [`Self::send_commitment_no_state_update`] for more info.
        pub fn send_htlc_and_commit<L: Deref>(&mut self, amount_msat: u64, payment_hash: PaymentHash, cltv_expiry: u32, source: HTLCSource, onion_routing_packet: msgs::OnionPacket, logger: &L) -> Result<Option<(msgs::UpdateAddHTLC, msgs::CommitmentSigned, ChannelMonitorUpdate)>, ChannelError> where L::Target: Logger {
-               match self.send_htlc(amount_msat, payment_hash, cltv_expiry, source, onion_routing_packet, logger)? {
+               match self.send_htlc(amount_msat, payment_hash, cltv_expiry, source, onion_routing_packet, false, logger)? {
                        Some(update_add_htlc) => {
                                let (commitment_signed, monitor_update) = self.send_commitment_no_status_check(logger)?;
                                Ok(Some((update_add_htlc, commitment_signed, monitor_update)))
@@ -5803,7 +5847,7 @@ impl<Signer: Sign> Channel<Signer> {
        /// holding cell HTLCs for payment failure.
        pub fn get_shutdown<K: Deref>(&mut self, keys_provider: &K, their_features: &InitFeatures, target_feerate_sats_per_kw: Option<u32>)
        -> Result<(msgs::Shutdown, Option<ChannelMonitorUpdate>, Vec<(HTLCSource, PaymentHash)>), APIError>
-       where K::Target: KeysInterface<Signer = Signer> {
+       where K::Target: KeysInterface {
                for htlc in self.pending_outbound_htlcs.iter() {
                        if let OutboundHTLCState::LocalAnnounced(_) = htlc.state {
                                return Err(APIError::APIMisuseError{err: "Cannot begin shutdown with pending HTLCs. Process pending events first".to_owned()});
@@ -5818,7 +5862,7 @@ impl<Signer: Sign> Channel<Signer> {
                        }
                }
                assert_eq!(self.channel_state & ChannelState::ShutdownComplete as u32, 0);
-               if self.channel_state & (ChannelState::PeerDisconnected as u32 | ChannelState::MonitorUpdateFailed as u32) != 0 {
+               if self.channel_state & (ChannelState::PeerDisconnected as u32 | ChannelState::MonitorUpdateInProgress as u32) != 0 {
                        return Err(APIError::ChannelUnavailable{err: "Cannot begin shutdown while peer is disconnected or we're waiting on a monitor update, maybe force-close instead?".to_owned()});
                }
 
@@ -5906,7 +5950,7 @@ impl<Signer: Sign> Channel<Signer> {
                        // funding transaction, don't return a funding txo (which prevents providing the
                        // monitor update to the user, even if we return one).
                        // See test_duplicate_chan_id and test_pre_lockin_no_chan_closed_update for more.
-                       if self.channel_state & (ChannelState::FundingSent as u32 | ChannelState::ChannelFunded as u32 | ChannelState::ShutdownComplete as u32) != 0 {
+                       if self.channel_state & (ChannelState::FundingSent as u32 | ChannelState::ChannelReady as u32 | ChannelState::ShutdownComplete as u32) != 0 {
                                self.latest_monitor_update_id += 1;
                                Some((funding_txo, ChannelMonitorUpdate {
                                        update_id: self.latest_monitor_update_id,
@@ -5919,9 +5963,21 @@ impl<Signer: Sign> Channel<Signer> {
                self.update_time_counter += 1;
                (monitor_update, dropped_outbound_htlcs)
        }
+
+       pub fn inflight_htlc_sources(&self) -> impl Iterator<Item=(&HTLCSource, &PaymentHash)> {
+               self.holding_cell_htlc_updates.iter()
+                       .flat_map(|htlc_update| {
+                               match htlc_update {
+                                       HTLCUpdateAwaitingACK::AddHTLC { source, payment_hash, .. }
+                                               => Some((source, payment_hash)),
+                                       _ => None,
+                               }
+                       })
+                       .chain(self.pending_outbound_htlcs.iter().map(|htlc| (&htlc.source, &htlc.payment_hash)))
+       }
 }
 
-const SERIALIZATION_VERSION: u8 = 2;
+const SERIALIZATION_VERSION: u8 = 3;
 const MIN_SERIALIZATION_VERSION: u8 = 2;
 
 impl_writeable_tlv_based_enum!(InboundHTLCRemovalReason,;
@@ -5983,9 +6039,13 @@ impl<Signer: Sign> Writeable for Channel<Signer> {
                // Note that we write out as if remove_uncommitted_htlcs_and_mark_paused had just been
                // called.
 
-               write_ver_prefix!(writer, SERIALIZATION_VERSION, MIN_SERIALIZATION_VERSION);
+               write_ver_prefix!(writer, MIN_SERIALIZATION_VERSION, MIN_SERIALIZATION_VERSION);
 
-               self.user_id.write(writer)?;
+               // `user_id` used to be a single u64 value. In order to remain backwards compatible with
+               // versions prior to 0.0.113, the u128 is serialized as two separate u64 values. We write
+               // the low bytes now and the optional high bytes later.
+               let user_id_low = self.user_id as u64;
+               user_id_low.write(writer)?;
 
                // Version 1 deserializers expected to read parts of the config object here. Version 2
                // deserializers (0.0.99) now read config through TLVs, and as we now require them for
@@ -6230,6 +6290,13 @@ impl<Signer: Sign> Writeable for Channel<Signer> {
                        if self.holder_max_htlc_value_in_flight_msat != Self::get_holder_max_htlc_value_in_flight_msat(self.channel_value_satoshis, &old_max_in_flight_percent_config)
                        { Some(self.holder_max_htlc_value_in_flight_msat) } else { None };
 
+               let channel_ready_event_emitted = Some(self.channel_ready_event_emitted);
+
+               // `user_id` used to be a single u64 value. In order to remain backwards compatible with
+               // versions prior to 0.0.113, the u128 is serialized as two separate u64 values. Therefore,
+               // we write the high bytes as an option here.
+               let user_id_high_opt = Some((self.user_id >> 64) as u64);
+
                write_tlv_fields!(writer, {
                        (0, self.announcement_sigs, option),
                        // minimum_depth and counterparty_selected_channel_reserve_satoshis used to have a
@@ -6252,6 +6319,9 @@ impl<Signer: Sign> Writeable for Channel<Signer> {
                        (17, self.announcement_sigs_state, required),
                        (19, self.latest_inbound_scid_alias, option),
                        (21, self.outbound_scid_alias, required),
+                       (23, channel_ready_event_emitted, option),
+                       (25, user_id_high_opt, option),
+                       (27, self.channel_keys_id, required),
                });
 
                Ok(())
@@ -6259,13 +6329,16 @@ impl<Signer: Sign> Writeable for Channel<Signer> {
 }
 
 const MAX_ALLOC_SIZE: usize = 64*1024;
-impl<'a, Signer: Sign, K: Deref> ReadableArgs<(&'a K, u32)> for Channel<Signer>
-               where K::Target: KeysInterface<Signer = Signer> {
+impl<'a, K: Deref> ReadableArgs<(&'a K, u32)> for Channel<<K::Target as SignerProvider>::Signer>
+               where K::Target: KeysInterface {
        fn read<R : io::Read>(reader: &mut R, args: (&'a K, u32)) -> Result<Self, DecodeError> {
                let (keys_source, serialized_height) = args;
                let ver = read_ver_prefix!(reader, SERIALIZATION_VERSION);
 
-               let user_id = Readable::read(reader)?;
+               // `user_id` used to be a single u64 value. In order to remain backwards compatible with
+               // versions prior to 0.0.113, the u128 is serialized as two separate u64 values. We read
+               // the low bytes now and the high bytes later.
+               let user_id_low: u64 = Readable::read(reader)?;
 
                let mut config = Some(LegacyChannelConfig::default());
                if ver == 1 {
@@ -6285,16 +6358,20 @@ impl<'a, Signer: Sign, K: Deref> ReadableArgs<(&'a K, u32)> for Channel<Signer>
 
                let latest_monitor_update_id = Readable::read(reader)?;
 
-               let keys_len: u32 = Readable::read(reader)?;
-               let mut keys_data = Vec::with_capacity(cmp::min(keys_len as usize, MAX_ALLOC_SIZE));
-               while keys_data.len() != keys_len as usize {
-                       // Read 1KB at a time to avoid accidentally allocating 4GB on corrupted channel keys
-                       let mut data = [0; 1024];
-                       let read_slice = &mut data[0..cmp::min(1024, keys_len as usize - keys_data.len())];
-                       reader.read_exact(read_slice)?;
-                       keys_data.extend_from_slice(read_slice);
+               let mut keys_data = None;
+               if ver <= 2 {
+                       // Read the serialize signer bytes. We'll choose to deserialize them or not based on whether
+                       // the `channel_keys_id` TLV is present below.
+                       let keys_len: u32 = Readable::read(reader)?;
+                       keys_data = Some(Vec::with_capacity(cmp::min(keys_len as usize, MAX_ALLOC_SIZE)));
+                       while keys_data.as_ref().unwrap().len() != keys_len as usize {
+                               // Read 1KB at a time to avoid accidentally allocating 4GB on corrupted channel keys
+                               let mut data = [0; 1024];
+                               let read_slice = &mut data[0..cmp::min(1024, keys_len as usize - keys_data.as_ref().unwrap().len())];
+                               reader.read_exact(read_slice)?;
+                               keys_data.as_mut().unwrap().extend_from_slice(read_slice);
+                       }
                }
-               let holder_signer = keys_source.read_chan_signer(&keys_data)?;
 
                // Read the old serialization for shutdown_pubkey, preferring the TLV field later if set.
                let mut shutdown_scriptpubkey = match <PublicKey as Readable>::read(reader) {
@@ -6509,6 +6586,10 @@ impl<'a, Signer: Sign, K: Deref> ReadableArgs<(&'a K, u32)> for Channel<Signer>
                let mut announcement_sigs_state = Some(AnnouncementSigsState::NotSent);
                let mut latest_inbound_scid_alias = None;
                let mut outbound_scid_alias = None;
+               let mut channel_ready_event_emitted = None;
+
+               let mut user_id_high_opt: Option<u64> = None;
+               let mut channel_keys_id: Option<[u8; 32]> = None;
 
                read_tlv_fields!(reader, {
                        (0, announcement_sigs, option),
@@ -6526,8 +6607,27 @@ impl<'a, Signer: Sign, K: Deref> ReadableArgs<(&'a K, u32)> for Channel<Signer>
                        (17, announcement_sigs_state, option),
                        (19, latest_inbound_scid_alias, option),
                        (21, outbound_scid_alias, option),
+                       (23, channel_ready_event_emitted, option),
+                       (25, user_id_high_opt, option),
+                       (27, channel_keys_id, option),
                });
 
+               let (channel_keys_id, holder_signer) = if let Some(channel_keys_id) = channel_keys_id {
+                       let mut holder_signer = keys_source.derive_channel_signer(channel_value_satoshis, channel_keys_id);
+                       // If we've gotten to the funding stage of the channel, populate the signer with its
+                       // required channel parameters.
+                       let non_shutdown_state = channel_state & (!MULTI_STATE_FLAGS);
+                       if non_shutdown_state >= (ChannelState::FundingCreated as u32) {
+                               holder_signer.provide_channel_parameters(&channel_parameters);
+                       }
+                       (channel_keys_id, holder_signer)
+               } else {
+                       // `keys_data` can be `None` if we had corrupted data.
+                       let keys_data = keys_data.ok_or(DecodeError::InvalidValue)?;
+                       let holder_signer = keys_source.read_chan_signer(&keys_data)?;
+                       (holder_signer.channel_keys_id(), holder_signer)
+               };
+
                if let Some(preimages) = preimages_opt {
                        let mut iter = preimages.into_iter();
                        for htlc in pending_outbound_htlcs.iter_mut() {
@@ -6562,6 +6662,11 @@ impl<'a, Signer: Sign, K: Deref> ReadableArgs<(&'a K, u32)> for Channel<Signer>
                let mut secp_ctx = Secp256k1::new();
                secp_ctx.seeded_randomize(&keys_source.get_secure_random_bytes());
 
+               // `user_id` used to be a single u64 value. In order to remain backwards
+               // compatible with versions prior to 0.0.113, the u128 is serialized as two
+               // separate u64 values.
+               let user_id = user_id_low as u128 + ((user_id_high_opt.unwrap_or(0) as u128) << 64);
+
                Ok(Channel {
                        user_id,
 
@@ -6666,10 +6771,13 @@ impl<'a, Signer: Sign, K: Deref> ReadableArgs<(&'a K, u32)> for Channel<Signer>
                        // Later in the ChannelManager deserialization phase we scan for channels and assign scid aliases if its missing
                        outbound_scid_alias: outbound_scid_alias.unwrap_or(0),
 
+                       channel_ready_event_emitted: channel_ready_event_emitted.unwrap_or(true),
+
                        #[cfg(any(test, fuzzing))]
                        historical_inbound_htlc_fulfills,
 
                        channel_type: channel_type.unwrap(),
+                       channel_keys_id,
                })
        }
 }
@@ -6683,24 +6791,24 @@ mod tests {
        use bitcoin::blockdata::opcodes;
        use bitcoin::network::constants::Network;
        use hex;
-       use ln::PaymentHash;
-       use ln::channelmanager::{self, HTLCSource, PaymentId};
-       use ln::channel::{Channel, InboundHTLCOutput, OutboundHTLCOutput, InboundHTLCState, OutboundHTLCState, HTLCCandidate, HTLCInitiator};
-       use ln::channel::{MAX_FUNDING_SATOSHIS_NO_WUMBO, TOTAL_BITCOIN_SUPPLY_SATOSHIS, MIN_THEIR_CHAN_RESERVE_SATOSHIS};
-       use ln::features::ChannelTypeFeatures;
-       use ln::msgs::{ChannelUpdate, DataLossProtect, DecodeError, OptionalField, UnsignedChannelUpdate, MAX_VALUE_MSAT};
-       use ln::script::ShutdownScript;
-       use ln::chan_utils;
-       use ln::chan_utils::{htlc_success_tx_weight, htlc_timeout_tx_weight};
-       use chain::BestBlock;
-       use chain::chaininterface::{FeeEstimator, LowerBoundedFeeEstimator, ConfirmationTarget};
-       use chain::keysinterface::{InMemorySigner, Recipient, KeyMaterial, KeysInterface};
-       use chain::transaction::OutPoint;
-       use util::config::UserConfig;
-       use util::enforcing_trait_impls::EnforcingSigner;
-       use util::errors::APIError;
-       use util::test_utils;
-       use util::test_utils::OnGetShutdownScriptpubkey;
+       use crate::ln::PaymentHash;
+       use crate::ln::channelmanager::{self, HTLCSource, PaymentId};
+       use crate::ln::channel::{Channel, InboundHTLCOutput, OutboundHTLCOutput, InboundHTLCState, OutboundHTLCState, HTLCCandidate, HTLCInitiator};
+       use crate::ln::channel::{MAX_FUNDING_SATOSHIS_NO_WUMBO, TOTAL_BITCOIN_SUPPLY_SATOSHIS, MIN_THEIR_CHAN_RESERVE_SATOSHIS};
+       use crate::ln::features::ChannelTypeFeatures;
+       use crate::ln::msgs::{ChannelUpdate, DataLossProtect, DecodeError, OptionalField, UnsignedChannelUpdate, MAX_VALUE_MSAT};
+       use crate::ln::script::ShutdownScript;
+       use crate::ln::chan_utils;
+       use crate::ln::chan_utils::{htlc_success_tx_weight, htlc_timeout_tx_weight};
+       use crate::chain::BestBlock;
+       use crate::chain::chaininterface::{FeeEstimator, LowerBoundedFeeEstimator, ConfirmationTarget};
+       use crate::chain::keysinterface::{BaseSign, InMemorySigner, Recipient, KeyMaterial, KeysInterface, EntropySource, NodeSigner, SignerProvider};
+       use crate::chain::transaction::OutPoint;
+       use crate::util::config::UserConfig;
+       use crate::util::enforcing_trait_impls::EnforcingSigner;
+       use crate::util::errors::APIError;
+       use crate::util::test_utils;
+       use crate::util::test_utils::OnGetShutdownScriptpubkey;
        use bitcoin::secp256k1::{Secp256k1, ecdsa::Signature, Scalar};
        use bitcoin::secp256k1::ffi::Signature as FFISignature;
        use bitcoin::secp256k1::{SecretKey,PublicKey};
@@ -6712,7 +6820,7 @@ mod tests {
        use bitcoin::bech32::u5;
        use bitcoin::PackedLockTime;
        use bitcoin::util::address::WitnessVersion;
-       use prelude::*;
+       use crate::prelude::*;
 
        struct TestFeeEstimator {
                fee_est: u32
@@ -6736,18 +6844,46 @@ mod tests {
                // arithmetic, causing a panic with debug assertions enabled.
                let fee_est = TestFeeEstimator { fee_est: 42 };
                let bounded_fee_estimator = LowerBoundedFeeEstimator::new(&fee_est);
-               assert!(Channel::<InMemorySigner>::check_remote_fee(&bounded_fee_estimator, u32::max_value()).is_err());
+               assert!(Channel::<InMemorySigner>::check_remote_fee(&bounded_fee_estimator,
+                       u32::max_value(), None, &&test_utils::TestLogger::new()).is_err());
        }
 
        struct Keys {
                signer: InMemorySigner,
        }
-       impl KeysInterface for Keys {
-               type Signer = InMemorySigner;
 
+       impl EntropySource for Keys {
+               fn get_secure_random_bytes(&self) -> [u8; 32] { [0; 32] }
+       }
+
+       impl NodeSigner for Keys {
                fn get_node_secret(&self, _recipient: Recipient) -> Result<SecretKey, ()> { panic!(); }
+
+               fn get_node_id(&self, recipient: Recipient) -> Result<PublicKey, ()> {
+                       let secp_ctx = Secp256k1::signing_only();
+                       Ok(PublicKey::from_secret_key(&secp_ctx, &self.get_node_secret(recipient)?))
+               }
+
                fn ecdh(&self, _recipient: Recipient, _other_key: &PublicKey, _tweak: Option<&Scalar>) -> Result<SharedSecret, ()> { panic!(); }
+
                fn get_inbound_payment_key_material(&self) -> KeyMaterial { panic!(); }
+
+               fn sign_invoice(&self, _hrp_bytes: &[u8], _invoice_data: &[u5], _recipient: Recipient) -> Result<RecoverableSignature, ()> { panic!(); }
+       }
+
+       impl SignerProvider for Keys {
+               type Signer = InMemorySigner;
+
+               fn generate_channel_keys_id(&self, _inbound: bool, _channel_value_satoshis: u64, _user_channel_id: u128) -> [u8; 32] {
+                       self.signer.channel_keys_id()
+               }
+
+               fn derive_channel_signer(&self, _channel_value_satoshis: u64, _channel_keys_id: [u8; 32]) -> Self::Signer {
+                       self.signer.clone()
+               }
+
+               fn read_chan_signer(&self, _data: &[u8]) -> Result<Self::Signer, DecodeError> { panic!(); }
+
                fn get_destination_script(&self) -> Script {
                        let secp_ctx = Secp256k1::signing_only();
                        let channel_monitor_claim_key = SecretKey::from_slice(&hex::decode("0fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff").unwrap()[..]).unwrap();
@@ -6760,15 +6896,10 @@ mod tests {
                        let channel_close_key = SecretKey::from_slice(&hex::decode("0fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff").unwrap()[..]).unwrap();
                        ShutdownScript::new_p2wpkh_from_pubkey(PublicKey::from_secret_key(&secp_ctx, &channel_close_key))
                }
-
-               fn get_channel_signer(&self, _inbound: bool, _channel_value_satoshis: u64) -> InMemorySigner {
-                       self.signer.clone()
-               }
-               fn get_secure_random_bytes(&self) -> [u8; 32] { [0; 32] }
-               fn read_chan_signer(&self, _data: &[u8]) -> Result<Self::Signer, DecodeError> { panic!(); }
-               fn sign_invoice(&self, _hrp_bytes: &[u8], _invoice_data: &[u5], _recipient: Recipient) -> Result<RecoverableSignature, ()> { panic!(); }
        }
 
+       impl KeysInterface for Keys {}
+
        #[cfg(not(feature = "grind_signatures"))]
        fn public_from_secret_hex(secp_ctx: &Secp256k1<bitcoin::secp256k1::All>, hex: &str) -> PublicKey {
                PublicKey::from_secret_key(&secp_ctx, &SecretKey::from_slice(&hex::decode(hex).unwrap()[..]).unwrap())
@@ -6976,10 +7107,10 @@ mod tests {
                }]};
                let funding_outpoint = OutPoint{ txid: tx.txid(), index: 0 };
                let funding_created_msg = node_a_chan.get_outbound_funding_created(tx.clone(), funding_outpoint, &&logger).unwrap();
-               let (funding_signed_msg, _, _) = node_b_chan.funding_created(&funding_created_msg, best_block, &&logger).unwrap();
+               let (funding_signed_msg, _, _) = node_b_chan.funding_created(&funding_created_msg, best_block, &&keys_provider, &&logger).unwrap();
 
                // Node B --> Node A: funding signed
-               let _ = node_a_chan.funding_signed(&funding_signed_msg, best_block, &&logger);
+               let _ = node_a_chan.funding_signed(&funding_signed_msg, best_block, &&keys_provider, &&logger);
 
                // Now disconnect the two nodes and check that the commitment point in
                // Node B's channel_reestablish message is sane.
@@ -7196,12 +7327,12 @@ mod tests {
                use bitcoin::hashes::hex::FromHex;
                use bitcoin::hash_types::Txid;
                use bitcoin::secp256k1::Message;
-               use chain::keysinterface::BaseSign;
-               use ln::PaymentPreimage;
-               use ln::channel::{HTLCOutputInCommitment ,TxCreationKeys};
-               use ln::chan_utils::{ChannelPublicKeys, HolderCommitmentTransaction, CounterpartyChannelTransactionParameters};
-               use util::logger::Logger;
-               use sync::Arc;
+               use crate::chain::keysinterface::BaseSign;
+               use crate::ln::PaymentPreimage;
+               use crate::ln::channel::{HTLCOutputInCommitment ,TxCreationKeys};
+               use crate::ln::chan_utils::{ChannelPublicKeys, HolderCommitmentTransaction, CounterpartyChannelTransactionParameters};
+               use crate::util::logger::Logger;
+               use crate::sync::Arc;
 
                // Test vectors from BOLT 3 Appendices C and F (anchors):
                let feeest = TestFeeEstimator{fee_est: 15000};
@@ -7220,7 +7351,7 @@ mod tests {
                        // These aren't set in the test vectors:
                        [0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff],
                        10_000_000,
-                       [0; 32]
+                       [0; 32],
                );
 
                assert_eq!(signer.pubkeys().funding_pubkey.serialize()[..],
@@ -7249,7 +7380,7 @@ mod tests {
                                selected_contest_delay: 144
                        });
                chan.channel_transaction_parameters.funding_outpoint = Some(funding_info);
-               signer.ready_channel(&chan.channel_transaction_parameters);
+               signer.provide_channel_parameters(&chan.channel_transaction_parameters);
 
                assert_eq!(counterparty_pubkeys.payment_point.serialize()[..],
                           hex::decode("032c0b7cf95324a07d05398b240174dc0c2be444d96b159aa6c7f7b1e668680991").unwrap()[..]);
@@ -7267,7 +7398,7 @@ mod tests {
                let per_commitment_secret = SecretKey::from_slice(&hex::decode("1f1e1d1c1b1a191817161514131211100f0e0d0c0b0a09080706050403020100").unwrap()[..]).unwrap();
                let per_commitment_point = PublicKey::from_secret_key(&secp_ctx, &per_commitment_secret);
                let htlc_basepoint = &chan.holder_signer.pubkeys().htlc_basepoint;
-               let keys = TxCreationKeys::derive_new(&secp_ctx, &per_commitment_point, delayed_payment_base, htlc_basepoint, &counterparty_pubkeys.revocation_basepoint, &counterparty_pubkeys.htlc_basepoint).unwrap();
+               let keys = TxCreationKeys::derive_new(&secp_ctx, &per_commitment_point, delayed_payment_base, htlc_basepoint, &counterparty_pubkeys.revocation_basepoint, &counterparty_pubkeys.htlc_basepoint);
 
                macro_rules! test_commitment {
                        ( $counterparty_sig_hex: expr, $sig_hex: expr, $tx_hex: expr, $($remain:tt)* ) => {
@@ -7338,7 +7469,7 @@ mod tests {
                                        let ref htlc = htlcs[$htlc_idx];
                                        let htlc_tx = chan_utils::build_htlc_transaction(&unsigned_tx.txid, chan.feerate_per_kw,
                                                chan.get_counterparty_selected_contest_delay().unwrap(),
-                                               &htlc, $opt_anchors, &keys.broadcaster_delayed_payment_key, &keys.revocation_key);
+                                               &htlc, $opt_anchors, false, &keys.broadcaster_delayed_payment_key, &keys.revocation_key);
                                        let htlc_redeemscript = chan_utils::get_htlc_redeemscript(&htlc, $opt_anchors, &keys);
                                        let htlc_sighashtype = if $opt_anchors { EcdsaSighashType::SinglePlusAnyoneCanPay } else { EcdsaSighashType::All };
                                        let htlc_sighash = Message::from_slice(&sighash::SighashCache::new(&htlc_tx).segwit_signature_hash(0, &htlc_redeemscript, htlc.amount_msat / 1000, htlc_sighashtype).unwrap()[..]).unwrap();
@@ -7920,16 +8051,16 @@ mod tests {
                let per_commitment_point = PublicKey::from_secret_key(&secp_ctx, &per_commitment_secret);
                assert_eq!(per_commitment_point.serialize()[..], hex::decode("025f7117a78150fe2ef97db7cfc83bd57b2e2c0d0dd25eaf467a4a1c2a45ce1486").unwrap()[..]);
 
-               assert_eq!(chan_utils::derive_public_key(&secp_ctx, &per_commitment_point, &base_point).unwrap().serialize()[..],
+               assert_eq!(chan_utils::derive_public_key(&secp_ctx, &per_commitment_point, &base_point).serialize()[..],
                                hex::decode("0235f2dbfaa89b57ec7b055afe29849ef7ddfeb1cefdb9ebdc43f5494984db29e5").unwrap()[..]);
 
-               assert_eq!(chan_utils::derive_private_key(&secp_ctx, &per_commitment_point, &base_secret).unwrap(),
+               assert_eq!(chan_utils::derive_private_key(&secp_ctx, &per_commitment_point, &base_secret),
                                SecretKey::from_slice(&hex::decode("cbced912d3b21bf196a766651e436aff192362621ce317704ea2f75d87e7be0f").unwrap()[..]).unwrap());
 
-               assert_eq!(chan_utils::derive_public_revocation_key(&secp_ctx, &per_commitment_point, &base_point).unwrap().serialize()[..],
+               assert_eq!(chan_utils::derive_public_revocation_key(&secp_ctx, &per_commitment_point, &base_point).serialize()[..],
                                hex::decode("02916e326636d19c33f13e8c0c3a03dd157f332f3e99c317c141dd865eb01f8ff0").unwrap()[..]);
 
-               assert_eq!(chan_utils::derive_private_revocation_key(&secp_ctx, &per_commitment_secret, &base_secret).unwrap(),
+               assert_eq!(chan_utils::derive_private_revocation_key(&secp_ctx, &per_commitment_secret, &base_secret),
                                SecretKey::from_slice(&hex::decode("d09ffff62ddb2297ab000cc85bcb4283fdeb6aa052affbc9dddcf33b61078110").unwrap()[..]).unwrap());
        }