Merge pull request #3125 from valentinewallace/2024-06-async-payments-prefactor
[rust-lightning] / lightning / src / ln / channel.rs
index 37ce1082e0a0065c9cd65662172735a0a3c4477b..f5c47260f6ef68842a0ff1c0d03e2935aa4a7560 100644 (file)
@@ -710,7 +710,7 @@ pub const MIN_THEIR_CHAN_RESERVE_SATOSHIS: u64 = 1000;
 pub(super) enum ChannelError {
        Ignore(String),
        Warn(String),
-       Close(String),
+       Close((String, ClosureReason)),
 }
 
 impl fmt::Debug for ChannelError {
@@ -718,7 +718,7 @@ impl fmt::Debug for ChannelError {
                match self {
                        &ChannelError::Ignore(ref e) => write!(f, "Ignore : {}", e),
                        &ChannelError::Warn(ref e) => write!(f, "Warn : {}", e),
-                       &ChannelError::Close(ref e) => write!(f, "Close : {}", e),
+                       &ChannelError::Close((ref e, _)) => write!(f, "Close : {}", e),
                }
        }
 }
@@ -728,14 +728,14 @@ impl fmt::Display for ChannelError {
                match self {
                        &ChannelError::Ignore(ref e) => write!(f, "{}", e),
                        &ChannelError::Warn(ref e) => write!(f, "{}", e),
-                       &ChannelError::Close(ref e) => write!(f, "{}", e),
+                       &ChannelError::Close((ref e, _)) => write!(f, "{}", e),
                }
        }
 }
 
 impl ChannelError {
        pub(super) fn close(err: String) -> Self {
-               ChannelError::Close(err.clone())
+               ChannelError::Close((err.clone(), ClosureReason::ProcessingError { err }))
        }
 }
 
@@ -939,6 +939,75 @@ pub(crate) struct ShutdownResult {
        pub(crate) channel_funding_txo: Option<OutPoint>,
 }
 
+/// Tracks the transaction number, along with current and next commitment points.
+/// This consolidates the logic to advance our commitment number and request new
+/// commitment points from our signer.
+#[derive(Debug, Copy, Clone)]
+enum HolderCommitmentPoint {
+       // TODO: add a variant for before our first commitment point is retrieved
+       /// We've advanced our commitment number and are waiting on the next commitment point.
+       /// Until the `get_per_commitment_point` signer method becomes async, this variant
+       /// will not be used.
+       PendingNext { transaction_number: u64, current: PublicKey },
+       /// Our current commitment point is ready, we've cached our next point,
+       /// and we are not pending a new one.
+       Available { transaction_number: u64, current: PublicKey, next: PublicKey },
+}
+
+impl HolderCommitmentPoint {
+       pub fn new<SP: Deref>(signer: &ChannelSignerType<SP>, secp_ctx: &Secp256k1<secp256k1::All>) -> Self
+               where SP::Target: SignerProvider
+       {
+               HolderCommitmentPoint::Available {
+                       transaction_number: INITIAL_COMMITMENT_NUMBER,
+                       current: signer.as_ref().get_per_commitment_point(INITIAL_COMMITMENT_NUMBER, secp_ctx),
+                       next: signer.as_ref().get_per_commitment_point(INITIAL_COMMITMENT_NUMBER - 1, secp_ctx),
+               }
+       }
+
+       pub fn is_available(&self) -> bool {
+               if let HolderCommitmentPoint::Available { .. } = self { true } else { false }
+       }
+
+       pub fn transaction_number(&self) -> u64 {
+               match self {
+                       HolderCommitmentPoint::PendingNext { transaction_number, .. } => *transaction_number,
+                       HolderCommitmentPoint::Available { transaction_number, .. } => *transaction_number,
+               }
+       }
+
+       pub fn current_point(&self) -> PublicKey {
+               match self {
+                       HolderCommitmentPoint::PendingNext { current, .. } => *current,
+                       HolderCommitmentPoint::Available { current, .. } => *current,
+               }
+       }
+
+       pub fn next_point(&self) -> Option<PublicKey> {
+               match self {
+                       HolderCommitmentPoint::PendingNext { .. } => None,
+                       HolderCommitmentPoint::Available { next, .. } => Some(*next),
+               }
+       }
+
+       pub fn advance<SP: Deref, L: Deref>(&mut self, signer: &ChannelSignerType<SP>, secp_ctx: &Secp256k1<secp256k1::All>, logger: &L)
+               where SP::Target: SignerProvider, L::Target: Logger
+       {
+               if let HolderCommitmentPoint::Available { transaction_number, next, .. } = self {
+                       *self = HolderCommitmentPoint::PendingNext {
+                               transaction_number: *transaction_number - 1,
+                               current: *next,
+                       };
+               }
+
+               if let HolderCommitmentPoint::PendingNext { transaction_number, current } = self {
+                       let next = signer.as_ref().get_per_commitment_point(*transaction_number - 1, secp_ctx);
+                       log_trace!(logger, "Retrieved next per-commitment point {}", *transaction_number - 1);
+                       *self = HolderCommitmentPoint::Available { transaction_number: *transaction_number, current: *current, next };
+               }
+       }
+}
+
 /// If the majority of the channels funds are to the fundee and the initiator holds only just
 /// enough funds to cover their reserve value, channels are at risk of getting "stuck". Because the
 /// initiator controls the feerate, if they then go to increase the channel fee, they may have no
@@ -1117,7 +1186,7 @@ pub(super) struct ChannelContext<SP: Deref> where SP::Target: SignerProvider {
        // generation start at 0 and count up...this simplifies some parts of implementation at the
        // cost of others, but should really just be changed.
 
-       cur_holder_commitment_transaction_number: u64,
+       holder_commitment_point: HolderCommitmentPoint,
        cur_counterparty_commitment_transaction_number: u64,
        value_to_self_msat: u64, // Excluding all pending_htlcs, fees, and anchor outputs
        pending_inbound_htlcs: Vec<InboundHTLCOutput>,
@@ -1559,6 +1628,9 @@ impl<SP: Deref> ChannelContext<SP> where SP::Target: SignerProvider  {
 
                let value_to_self_msat = our_funding_satoshis * 1000 + msg_push_msat;
 
+               let holder_signer = ChannelSignerType::Ecdsa(holder_signer);
+               let holder_commitment_point = HolderCommitmentPoint::new(&holder_signer, &secp_ctx);
+
                // TODO(dual_funding): Checks for `funding_feerate_sat_per_1000_weight`?
 
                let channel_context = ChannelContext {
@@ -1584,11 +1656,11 @@ impl<SP: Deref> ChannelContext<SP> where SP::Target: SignerProvider  {
 
                        latest_monitor_update_id: 0,
 
-                       holder_signer: ChannelSignerType::Ecdsa(holder_signer),
+                       holder_signer,
                        shutdown_scriptpubkey,
                        destination_script,
 
-                       cur_holder_commitment_transaction_number: INITIAL_COMMITMENT_NUMBER,
+                       holder_commitment_point,
                        cur_counterparty_commitment_transaction_number: INITIAL_COMMITMENT_NUMBER,
                        value_to_self_msat,
 
@@ -1783,6 +1855,9 @@ impl<SP: Deref> ChannelContext<SP> where SP::Target: SignerProvider  {
 
                let temporary_channel_id = temporary_channel_id.unwrap_or_else(|| ChannelId::temporary_from_entropy_source(entropy_source));
 
+               let holder_signer = ChannelSignerType::Ecdsa(holder_signer);
+               let holder_commitment_point = HolderCommitmentPoint::new(&holder_signer, &secp_ctx);
+
                Ok(Self {
                        user_id,
 
@@ -1806,11 +1881,11 @@ impl<SP: Deref> ChannelContext<SP> where SP::Target: SignerProvider  {
 
                        latest_monitor_update_id: 0,
 
-                       holder_signer: ChannelSignerType::Ecdsa(holder_signer),
+                       holder_signer,
                        shutdown_scriptpubkey,
                        destination_script,
 
-                       cur_holder_commitment_transaction_number: INITIAL_COMMITMENT_NUMBER,
+                       holder_commitment_point,
                        cur_counterparty_commitment_transaction_number: INITIAL_COMMITMENT_NUMBER,
                        value_to_self_msat,
 
@@ -2043,8 +2118,8 @@ impl<SP: Deref> ChannelContext<SP> where SP::Target: SignerProvider  {
 
        /// Returns the holder signer for this channel.
        #[cfg(test)]
-       pub fn get_signer(&self) -> &ChannelSignerType<SP> {
-               return &self.holder_signer
+       pub fn get_mut_signer(&mut self) -> &mut ChannelSignerType<SP> {
+               return &mut self.holder_signer
        }
 
        /// Only allowed immediately after deserialization if get_outbound_scid_alias returns 0,
@@ -2071,6 +2146,143 @@ impl<SP: Deref> ChannelContext<SP> where SP::Target: SignerProvider  {
                }
        }
 
+       /// Performs checks against necessary constraints after receiving either an `accept_channel` or
+       /// `accept_channel2` message.
+       pub fn do_accept_channel_checks(
+               &mut self, default_limits: &ChannelHandshakeLimits, their_features: &InitFeatures,
+               common_fields: &msgs::CommonAcceptChannelFields, channel_reserve_satoshis: u64,
+       ) -> Result<(), ChannelError> {
+               let peer_limits = if let Some(ref limits) = self.inbound_handshake_limits_override { limits } else { default_limits };
+
+               // Check sanity of message fields:
+               if !self.is_outbound() {
+                       return Err(ChannelError::close("Got an accept_channel message from an inbound peer".to_owned()));
+               }
+               if !matches!(self.channel_state, ChannelState::NegotiatingFunding(flags) if flags == NegotiatingFundingFlags::OUR_INIT_SENT) {
+                       return Err(ChannelError::close("Got an accept_channel message at a strange time".to_owned()));
+               }
+               if common_fields.dust_limit_satoshis > 21000000 * 100000000 {
+                       return Err(ChannelError::close(format!("Peer never wants payout outputs? dust_limit_satoshis was {}", common_fields.dust_limit_satoshis)));
+               }
+               if channel_reserve_satoshis > self.channel_value_satoshis {
+                       return Err(ChannelError::close(format!("Bogus channel_reserve_satoshis ({}). Must not be greater than ({})", channel_reserve_satoshis, self.channel_value_satoshis)));
+               }
+               if common_fields.dust_limit_satoshis > self.holder_selected_channel_reserve_satoshis {
+                       return Err(ChannelError::close(format!("Dust limit ({}) is bigger than our channel reserve ({})", common_fields.dust_limit_satoshis, self.holder_selected_channel_reserve_satoshis)));
+               }
+               if channel_reserve_satoshis > self.channel_value_satoshis - self.holder_selected_channel_reserve_satoshis {
+                       return Err(ChannelError::close(format!("Bogus channel_reserve_satoshis ({}). Must not be greater than channel value minus our reserve ({})",
+                               channel_reserve_satoshis, self.channel_value_satoshis - self.holder_selected_channel_reserve_satoshis)));
+               }
+               let full_channel_value_msat = (self.channel_value_satoshis - channel_reserve_satoshis) * 1000;
+               if common_fields.htlc_minimum_msat >= full_channel_value_msat {
+                       return Err(ChannelError::close(format!("Minimum htlc value ({}) is full channel value ({})", common_fields.htlc_minimum_msat, full_channel_value_msat)));
+               }
+               let max_delay_acceptable = u16::min(peer_limits.their_to_self_delay, MAX_LOCAL_BREAKDOWN_TIMEOUT);
+               if common_fields.to_self_delay > max_delay_acceptable {
+                       return Err(ChannelError::close(format!("They wanted our payments to be delayed by a needlessly long period. Upper limit: {}. Actual: {}", max_delay_acceptable, common_fields.to_self_delay)));
+               }
+               if common_fields.max_accepted_htlcs < 1 {
+                       return Err(ChannelError::close("0 max_accepted_htlcs makes for a useless channel".to_owned()));
+               }
+               if common_fields.max_accepted_htlcs > MAX_HTLCS {
+                       return Err(ChannelError::close(format!("max_accepted_htlcs was {}. It must not be larger than {}", common_fields.max_accepted_htlcs, MAX_HTLCS)));
+               }
+
+               // Now check against optional parameters as set by config...
+               if common_fields.htlc_minimum_msat > peer_limits.max_htlc_minimum_msat {
+                       return Err(ChannelError::close(format!("htlc_minimum_msat ({}) is higher than the user specified limit ({})", common_fields.htlc_minimum_msat, peer_limits.max_htlc_minimum_msat)));
+               }
+               if common_fields.max_htlc_value_in_flight_msat < peer_limits.min_max_htlc_value_in_flight_msat {
+                       return Err(ChannelError::close(format!("max_htlc_value_in_flight_msat ({}) is less than the user specified limit ({})", common_fields.max_htlc_value_in_flight_msat, peer_limits.min_max_htlc_value_in_flight_msat)));
+               }
+               if channel_reserve_satoshis > peer_limits.max_channel_reserve_satoshis {
+                       return Err(ChannelError::close(format!("channel_reserve_satoshis ({}) is higher than the user specified limit ({})", channel_reserve_satoshis, peer_limits.max_channel_reserve_satoshis)));
+               }
+               if common_fields.max_accepted_htlcs < peer_limits.min_max_accepted_htlcs {
+                       return Err(ChannelError::close(format!("max_accepted_htlcs ({}) is less than the user specified limit ({})", common_fields.max_accepted_htlcs, peer_limits.min_max_accepted_htlcs)));
+               }
+               if common_fields.dust_limit_satoshis < MIN_CHAN_DUST_LIMIT_SATOSHIS {
+                       return Err(ChannelError::close(format!("dust_limit_satoshis ({}) is less than the implementation limit ({})", common_fields.dust_limit_satoshis, MIN_CHAN_DUST_LIMIT_SATOSHIS)));
+               }
+               if common_fields.dust_limit_satoshis > MAX_CHAN_DUST_LIMIT_SATOSHIS {
+                       return Err(ChannelError::close(format!("dust_limit_satoshis ({}) is greater than the implementation limit ({})", common_fields.dust_limit_satoshis, MAX_CHAN_DUST_LIMIT_SATOSHIS)));
+               }
+               if common_fields.minimum_depth > peer_limits.max_minimum_depth {
+                       return Err(ChannelError::close(format!("We consider the minimum depth to be unreasonably large. Expected minimum: ({}). Actual: ({})", peer_limits.max_minimum_depth, common_fields.minimum_depth)));
+               }
+
+               if let Some(ty) = &common_fields.channel_type {
+                       if *ty != self.channel_type {
+                               return Err(ChannelError::close("Channel Type in accept_channel didn't match the one sent in open_channel.".to_owned()));
+                       }
+               } else if their_features.supports_channel_type() {
+                       // Assume they've accepted the channel type as they said they understand it.
+               } else {
+                       let channel_type = ChannelTypeFeatures::from_init(&their_features);
+                       if channel_type != ChannelTypeFeatures::only_static_remote_key() {
+                               return Err(ChannelError::close("Only static_remote_key is supported for non-negotiated channel types".to_owned()));
+                       }
+                       self.channel_type = channel_type.clone();
+                       self.channel_transaction_parameters.channel_type_features = channel_type;
+               }
+
+               let counterparty_shutdown_scriptpubkey = if their_features.supports_upfront_shutdown_script() {
+                       match &common_fields.shutdown_scriptpubkey {
+                               &Some(ref script) => {
+                                       // Peer is signaling upfront_shutdown and has opt-out with a 0-length script. We don't enforce anything
+                                       if script.len() == 0 {
+                                               None
+                                       } else {
+                                               if !script::is_bolt2_compliant(&script, their_features) {
+                                                       return Err(ChannelError::close(format!("Peer is signaling upfront_shutdown but has provided an unacceptable scriptpubkey format: {}", script)));
+                                               }
+                                               Some(script.clone())
+                                       }
+                               },
+                               // Peer is signaling upfront shutdown but don't opt-out with correct mechanism (a.k.a 0-length script). Peer looks buggy, we fail the channel
+                               &None => {
+                                       return Err(ChannelError::close("Peer is signaling upfront_shutdown but we don't get any script. Use 0-length script to opt-out".to_owned()));
+                               }
+                       }
+               } else { None };
+
+               self.counterparty_dust_limit_satoshis = common_fields.dust_limit_satoshis;
+               self.counterparty_max_htlc_value_in_flight_msat = cmp::min(common_fields.max_htlc_value_in_flight_msat, self.channel_value_satoshis * 1000);
+               self.counterparty_selected_channel_reserve_satoshis = Some(channel_reserve_satoshis);
+               self.counterparty_htlc_minimum_msat = common_fields.htlc_minimum_msat;
+               self.counterparty_max_accepted_htlcs = common_fields.max_accepted_htlcs;
+
+               if peer_limits.trust_own_funding_0conf {
+                       self.minimum_depth = Some(common_fields.minimum_depth);
+               } else {
+                       self.minimum_depth = Some(cmp::max(1, common_fields.minimum_depth));
+               }
+
+               let counterparty_pubkeys = ChannelPublicKeys {
+                       funding_pubkey: common_fields.funding_pubkey,
+                       revocation_basepoint: RevocationBasepoint::from(common_fields.revocation_basepoint),
+                       payment_point: common_fields.payment_basepoint,
+                       delayed_payment_basepoint: DelayedPaymentBasepoint::from(common_fields.delayed_payment_basepoint),
+                       htlc_basepoint: HtlcBasepoint::from(common_fields.htlc_basepoint)
+               };
+
+               self.channel_transaction_parameters.counterparty_parameters = Some(CounterpartyChannelTransactionParameters {
+                       selected_contest_delay: common_fields.to_self_delay,
+                       pubkeys: counterparty_pubkeys,
+               });
+
+               self.counterparty_cur_commitment_point = Some(common_fields.first_per_commitment_point);
+               self.counterparty_shutdown_scriptpubkey = counterparty_shutdown_scriptpubkey;
+
+               self.channel_state = ChannelState::NegotiatingFunding(
+                       NegotiatingFundingFlags::OUR_INIT_SENT | NegotiatingFundingFlags::THEIR_INIT_SENT
+               );
+               self.inbound_handshake_limits_override = None; // We're done enforcing limits on our peer's handshake now.
+
+               Ok(())
+       }
+
        /// 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
@@ -2504,8 +2716,8 @@ impl<SP: Deref> ChannelContext<SP> where SP::Target: SignerProvider  {
        /// 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) -> TxCreationKeys {
-               let per_commitment_point = self.holder_signer.as_ref().get_per_commitment_point(commitment_number, &self.secp_ctx);
+       fn build_holder_transaction_keys(&self) -> TxCreationKeys {
+               let per_commitment_point = self.holder_commitment_point.current_point();
                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();
@@ -3512,7 +3724,12 @@ impl<SP: Deref> Channel<SP> where
                                        return Ok(());
                                }
                        }
-                       return Err(ChannelError::close(format!("Peer's feerate much too low. Actual: {}. Our expected lower limit: {}", feerate_per_kw, lower_limit)));
+                       return Err(ChannelError::Close((format!(
+                               "Peer's feerate much too low. Actual: {}. Our expected lower limit: {}", feerate_per_kw, lower_limit
+                       ), ClosureReason::PeerFeerateTooLow {
+                               peer_feerate_sat_per_kw: feerate_per_kw,
+                               required_feerate_sat_per_kw: lower_limit,
+                       })));
                }
                Ok(())
        }
@@ -4201,9 +4418,9 @@ impl<SP: Deref> Channel<SP> where
 
                let funding_script = self.context.get_funding_redeemscript();
 
-               let keys = self.context.build_holder_transaction_keys(self.context.cur_holder_commitment_transaction_number);
+               let keys = self.context.build_holder_transaction_keys();
 
-               let commitment_stats = self.context.build_commitment_transaction(self.context.cur_holder_commitment_transaction_number, &keys, true, false, logger);
+               let commitment_stats = self.context.build_commitment_transaction(self.context.holder_commitment_point.transaction_number(), &keys, true, false, logger);
                let commitment_txid = {
                        let trusted_tx = commitment_stats.tx.trust();
                        let bitcoin_tx = trusted_tx.built_transaction();
@@ -4366,7 +4583,7 @@ impl<SP: Deref> Channel<SP> where
                        channel_id: Some(self.context.channel_id()),
                };
 
-               self.context.cur_holder_commitment_transaction_number -= 1;
+               self.context.holder_commitment_point.advance(&self.context.holder_signer, &self.context.secp_ctx, logger);
                self.context.expecting_peer_commitment_signed = false;
                // Note that if we need_commitment & !AwaitingRemoteRevoke we'll call
                // build_commitment_no_status_check() next which will reset this to RAAFirst.
@@ -4877,8 +5094,8 @@ impl<SP: Deref> Channel<SP> where
                // Before proposing a feerate update, check that we can actually afford the new fee.
                let dust_exposure_limiting_feerate = self.context.get_dust_exposure_limiting_feerate(&fee_estimator);
                let htlc_stats = self.context.get_pending_htlc_stats(Some(feerate_per_kw), dust_exposure_limiting_feerate);
-               let keys = self.context.build_holder_transaction_keys(self.context.cur_holder_commitment_transaction_number);
-               let commitment_stats = self.context.build_commitment_transaction(self.context.cur_holder_commitment_transaction_number, &keys, true, true, logger);
+               let keys = self.context.build_holder_transaction_keys();
+               let commitment_stats = self.context.build_commitment_transaction(self.context.holder_commitment_point.transaction_number(), &keys, true, true, logger);
                let buffer_fee_msat = commit_tx_fee_sat(feerate_per_kw, commitment_stats.num_nondust_htlcs + htlc_stats.on_holder_tx_outbound_holding_cell_htlcs_count as usize + CONCURRENT_INBOUND_HTLC_FEE_BUFFER as usize, self.context.get_channel_type()) * 1000;
                let holder_balance_msat = commitment_stats.local_balance_msat - htlc_stats.outbound_holding_cell_msat;
                if holder_balance_msat < buffer_fee_msat  + self.context.counterparty_selected_channel_reserve_satoshis.unwrap() * 1000 {
@@ -5060,12 +5277,7 @@ impl<SP: Deref> Channel<SP> where
                        assert!(!self.context.is_outbound() || self.context.minimum_depth == Some(0),
                                "Funding transaction broadcast by the local client before it should have - LDK didn't do it!");
                        self.context.monitor_pending_channel_ready = false;
-                       let next_per_commitment_point = self.context.holder_signer.as_ref().get_per_commitment_point(self.context.cur_holder_commitment_transaction_number, &self.context.secp_ctx);
-                       Some(msgs::ChannelReady {
-                               channel_id: self.context.channel_id(),
-                               next_per_commitment_point,
-                               short_channel_id_alias: Some(self.context.outbound_scid_alias),
-                       })
+                       Some(self.get_channel_ready())
                } else { None };
 
                let announcement_sigs = self.get_announcement_sigs(node_signer, chain_hash, user_config, best_block_height, logger);
@@ -5112,6 +5324,26 @@ impl<SP: Deref> Channel<SP> where
                }
        }
 
+       pub fn check_for_stale_feerate<L: Logger>(&mut self, logger: &L, min_feerate: u32) -> Result<(), ClosureReason> {
+               if self.context.is_outbound() {
+                       // While its possible our fee is too low for an outbound channel because we've been
+                       // unable to increase the fee, we don't try to force-close directly here.
+                       return Ok(());
+               }
+               if self.context.feerate_per_kw < min_feerate {
+                       log_info!(logger,
+                               "Closing channel as feerate of {} is below required {} (the minimum required rate over the past day)",
+                               self.context.feerate_per_kw, min_feerate
+                       );
+                       Err(ClosureReason::PeerFeerateTooLow {
+                               peer_feerate_sat_per_kw: self.context.feerate_per_kw,
+                               required_feerate_sat_per_kw: min_feerate,
+                       })
+               } else {
+                       Ok(())
+               }
+       }
+
        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
        {
@@ -5151,7 +5383,7 @@ impl<SP: Deref> Channel<SP> where
                        self.context.get_funding_signed_msg(logger).1
                } else { None };
                let channel_ready = if funding_signed.is_some() {
-                       self.check_get_channel_ready(0)
+                       self.check_get_channel_ready(0, logger)
                } else { None };
 
                log_trace!(logger, "Signer unblocked with {} commitment_update, {} funding_signed and {} channel_ready",
@@ -5167,8 +5399,11 @@ impl<SP: Deref> Channel<SP> where
        }
 
        fn get_last_revoke_and_ack(&self) -> msgs::RevokeAndACK {
-               let next_per_commitment_point = self.context.holder_signer.as_ref().get_per_commitment_point(self.context.cur_holder_commitment_transaction_number, &self.context.secp_ctx);
-               let per_commitment_secret = self.context.holder_signer.as_ref().release_commitment_secret(self.context.cur_holder_commitment_transaction_number + 2);
+               debug_assert!(self.context.holder_commitment_point.transaction_number() <= INITIAL_COMMITMENT_NUMBER + 2);
+               // TODO: handle non-available case when get_per_commitment_point becomes async
+               debug_assert!(self.context.holder_commitment_point.is_available());
+               let next_per_commitment_point = self.context.holder_commitment_point.current_point();
+               let per_commitment_secret = self.context.holder_signer.as_ref().release_commitment_secret(self.context.holder_commitment_point.transaction_number() + 2);
                msgs::RevokeAndACK {
                        channel_id: self.context.channel_id,
                        per_commitment_secret,
@@ -5301,7 +5536,7 @@ impl<SP: Deref> Channel<SP> where
                        return Err(ChannelError::close("Peer sent an invalid channel_reestablish to force close in a non-standard way".to_owned()));
                }
 
-               let our_commitment_transaction = INITIAL_COMMITMENT_NUMBER - self.context.cur_holder_commitment_transaction_number - 1;
+               let our_commitment_transaction = INITIAL_COMMITMENT_NUMBER - self.context.holder_commitment_point.transaction_number() - 1;
                if msg.next_remote_commitment_number > 0 {
                        let expected_point = self.context.holder_signer.as_ref().get_per_commitment_point(INITIAL_COMMITMENT_NUMBER - msg.next_remote_commitment_number + 1, &self.context.secp_ctx);
                        let given_secret = SecretKey::from_slice(&msg.your_last_per_commitment_secret)
@@ -5363,13 +5598,8 @@ impl<SP: Deref> Channel<SP> where
                        }
 
                        // We have OurChannelReady set!
-                       let next_per_commitment_point = self.context.holder_signer.as_ref().get_per_commitment_point(self.context.cur_holder_commitment_transaction_number, &self.context.secp_ctx);
                        return Ok(ReestablishResponses {
-                               channel_ready: Some(msgs::ChannelReady {
-                                       channel_id: self.context.channel_id(),
-                                       next_per_commitment_point,
-                                       short_channel_id_alias: Some(self.context.outbound_scid_alias),
-                               }),
+                               channel_ready: Some(self.get_channel_ready()),
                                raa: None, commitment_update: None,
                                order: RAACommitmentOrder::CommitmentFirst,
                                shutdown_msg, announcement_sigs,
@@ -5406,14 +5636,9 @@ impl<SP: Deref> Channel<SP> where
                }
                let next_counterparty_commitment_number = INITIAL_COMMITMENT_NUMBER - self.context.cur_counterparty_commitment_transaction_number + if is_awaiting_remote_revoke { 1 } else { 0 };
 
-               let channel_ready = if msg.next_local_commitment_number == 1 && INITIAL_COMMITMENT_NUMBER - self.context.cur_holder_commitment_transaction_number == 1 {
+               let channel_ready = if msg.next_local_commitment_number == 1 && INITIAL_COMMITMENT_NUMBER - self.context.holder_commitment_point.transaction_number() == 1 {
                        // We should never have to worry about MonitorUpdateInProgress resending ChannelReady
-                       let next_per_commitment_point = self.context.holder_signer.as_ref().get_per_commitment_point(self.context.cur_holder_commitment_transaction_number, &self.context.secp_ctx);
-                       Some(msgs::ChannelReady {
-                               channel_id: self.context.channel_id(),
-                               next_per_commitment_point,
-                               short_channel_id_alias: Some(self.context.outbound_scid_alias),
-                       })
+                       Some(self.get_channel_ready())
                } else { None };
 
                if msg.next_local_commitment_number == next_counterparty_commitment_number {
@@ -6059,7 +6284,7 @@ impl<SP: Deref> Channel<SP> where
        }
 
        pub fn get_cur_holder_commitment_transaction_number(&self) -> u64 {
-               self.context.cur_holder_commitment_transaction_number + 1
+               self.context.holder_commitment_point.transaction_number() + 1
        }
 
        pub fn get_cur_counterparty_commitment_transaction_number(&self) -> u64 {
@@ -6174,7 +6399,7 @@ impl<SP: Deref> Channel<SP> where
                        debug_assert!(self.context.minimum_depth.unwrap_or(1) > 0);
                        return true;
                }
-               if self.context.cur_holder_commitment_transaction_number == INITIAL_COMMITMENT_NUMBER - 1 &&
+               if self.context.holder_commitment_point.transaction_number() == INITIAL_COMMITMENT_NUMBER - 1 &&
                        self.context.cur_counterparty_commitment_transaction_number == INITIAL_COMMITMENT_NUMBER - 1 {
                        // If we're a 0-conf channel, we'll move beyond AwaitingChannelReady immediately even while
                        // waiting for the initial monitor persistence. Thus, we check if our commitment
@@ -6233,7 +6458,9 @@ impl<SP: Deref> Channel<SP> where
                self.context.channel_update_status = status;
        }
 
-       fn check_get_channel_ready(&mut self, height: u32) -> Option<msgs::ChannelReady> {
+       fn check_get_channel_ready<L: Deref>(&mut self, height: u32, logger: &L) -> Option<msgs::ChannelReady>
+               where L::Target: Logger
+       {
                // Called:
                //  * always when a new block/transactions are confirmed with the new height
                //  * when funding is signed with a height of 0
@@ -6253,6 +6480,8 @@ impl<SP: Deref> Channel<SP> where
                // If we're still pending the signature on a funding transaction, then we're not ready to send a
                // channel_ready yet.
                if self.context.signer_pending_funding {
+                       // TODO: set signer_pending_channel_ready
+                       log_debug!(logger, "Can't produce channel_ready: the signer is pending funding.");
                        return None;
                }
 
@@ -6285,22 +6514,35 @@ impl<SP: Deref> Channel<SP> where
                        false
                };
 
-               if need_commitment_update {
-                       if !self.context.channel_state.is_monitor_update_in_progress() {
-                               if !self.context.channel_state.is_peer_disconnected() {
-                                       let next_per_commitment_point =
-                                               self.context.holder_signer.as_ref().get_per_commitment_point(INITIAL_COMMITMENT_NUMBER - 1, &self.context.secp_ctx);
-                                       return Some(msgs::ChannelReady {
-                                               channel_id: self.context.channel_id,
-                                               next_per_commitment_point,
-                                               short_channel_id_alias: Some(self.context.outbound_scid_alias),
-                                       });
-                               }
-                       } else {
-                               self.context.monitor_pending_channel_ready = true;
-                       }
+               if !need_commitment_update {
+                       log_debug!(logger, "Not producing channel_ready: we do not need a commitment update");
+                       return None;
+               }
+
+               if self.context.channel_state.is_monitor_update_in_progress() {
+                       log_debug!(logger, "Not producing channel_ready: a monitor update is in progress. Setting monitor_pending_channel_ready.");
+                       self.context.monitor_pending_channel_ready = true;
+                       return None;
+               }
+
+               if self.context.channel_state.is_peer_disconnected() {
+                       log_debug!(logger, "Not producing channel_ready: the peer is disconnected.");
+                       return None;
+               }
+
+               // TODO: when get_per_commiment_point becomes async, check if the point is
+               // available, if not, set signer_pending_channel_ready and return None
+
+               Some(self.get_channel_ready())
+       }
+
+       fn get_channel_ready(&self) -> msgs::ChannelReady {
+               debug_assert!(self.context.holder_commitment_point.is_available());
+               msgs::ChannelReady {
+                       channel_id: self.context.channel_id(),
+                       next_per_commitment_point: self.context.holder_commitment_point.current_point(),
+                       short_channel_id_alias: Some(self.context.outbound_scid_alias),
                }
-               None
        }
 
        /// When a transaction is confirmed, we check whether it is or spends the funding transaction
@@ -6367,7 +6609,7 @@ impl<SP: Deref> Channel<SP> where
                                        // If we allow 1-conf funding, we may need to check for channel_ready here and
                                        // send it immediately instead of waiting for a best_block_updated call (which
                                        // may have already happened for this block).
-                                       if let Some(channel_ready) = self.check_get_channel_ready(height) {
+                                       if let Some(channel_ready) = self.check_get_channel_ready(height, logger) {
                                                log_info!(logger, "Sending a channel_ready to our peer for channel {}", &self.context.channel_id);
                                                let announcement_sigs = self.get_announcement_sigs(node_signer, chain_hash, user_config, height, logger);
                                                msgs = (Some(channel_ready), announcement_sigs);
@@ -6433,7 +6675,7 @@ impl<SP: Deref> Channel<SP> where
 
                self.context.update_time_counter = cmp::max(self.context.update_time_counter, highest_header_time);
 
-               if let Some(channel_ready) = self.check_get_channel_ready(height) {
+               if let Some(channel_ready) = self.check_get_channel_ready(height, logger) {
                        let announcement_sigs = if let Some((chain_hash, node_signer, user_config)) = chain_node_signer {
                                self.get_announcement_sigs(node_signer, chain_hash, user_config, height, logger)
                        } else { None };
@@ -6736,7 +6978,7 @@ impl<SP: Deref> Channel<SP> where
 
                        // next_local_commitment_number is the next commitment_signed number we expect to
                        // receive (indicating if they need to resend one that we missed).
-                       next_local_commitment_number: INITIAL_COMMITMENT_NUMBER - self.context.cur_holder_commitment_transaction_number,
+                       next_local_commitment_number: INITIAL_COMMITMENT_NUMBER - self.context.holder_commitment_point.transaction_number(),
                        // We have to set next_remote_commitment_number to the next revoke_and_ack we expect to
                        // receive, however we track it by the next commitment number for a remote transaction
                        // (which is one further, as they always revoke previous commitment transaction, not
@@ -7288,7 +7530,7 @@ impl<SP: Deref> OutboundV1Channel<SP> where SP::Target: SignerProvider {
                }
                if self.context.commitment_secrets.get_min_seen_secret() != (1 << 48) ||
                                self.context.cur_counterparty_commitment_transaction_number != INITIAL_COMMITMENT_NUMBER ||
-                               self.context.cur_holder_commitment_transaction_number != INITIAL_COMMITMENT_NUMBER {
+                               self.context.holder_commitment_point.transaction_number() != INITIAL_COMMITMENT_NUMBER {
                        panic!("Should not have advanced channel commitment tx numbers prior to funding_created");
                }
 
@@ -7343,7 +7585,7 @@ impl<SP: Deref> OutboundV1Channel<SP> where SP::Target: SignerProvider {
        /// Returns true if we can resume the channel by sending the [`msgs::OpenChannel`] again.
        pub fn is_resumable(&self) -> bool {
                !self.context.have_received_message() &&
-                       self.context.cur_holder_commitment_transaction_number == INITIAL_COMMITMENT_NUMBER
+                       self.context.holder_commitment_point.transaction_number() == INITIAL_COMMITMENT_NUMBER
        }
 
        pub fn get_open_channel(&self, chain_hash: ChainHash) -> msgs::OpenChannel {
@@ -7354,11 +7596,12 @@ impl<SP: Deref> OutboundV1Channel<SP> where SP::Target: SignerProvider {
                        panic!("Cannot generate an open_channel after we've moved forward");
                }
 
-               if self.context.cur_holder_commitment_transaction_number != INITIAL_COMMITMENT_NUMBER {
+               if self.context.holder_commitment_point.transaction_number() != INITIAL_COMMITMENT_NUMBER {
                        panic!("Tried to send an open_channel for a channel that has already advanced");
                }
 
-               let first_per_commitment_point = self.context.holder_signer.as_ref().get_per_commitment_point(self.context.cur_holder_commitment_transaction_number, &self.context.secp_ctx);
+               debug_assert!(self.context.holder_commitment_point.is_available());
+               let first_per_commitment_point = self.context.holder_commitment_point.current_point();
                let keys = self.context.get_holder_pubkeys();
 
                msgs::OpenChannel {
@@ -7391,136 +7634,11 @@ impl<SP: Deref> OutboundV1Channel<SP> where SP::Target: SignerProvider {
        }
 
        // Message handlers
-       pub fn accept_channel(&mut self, msg: &msgs::AcceptChannel, default_limits: &ChannelHandshakeLimits, their_features: &InitFeatures) -> Result<(), ChannelError> {
-               let peer_limits = if let Some(ref limits) = self.context.inbound_handshake_limits_override { limits } else { default_limits };
-
-               // Check sanity of message fields:
-               if !self.context.is_outbound() {
-                       return Err(ChannelError::close("Got an accept_channel message from an inbound peer".to_owned()));
-               }
-               if !matches!(self.context.channel_state, ChannelState::NegotiatingFunding(flags) if flags == NegotiatingFundingFlags::OUR_INIT_SENT) {
-                       return Err(ChannelError::close("Got an accept_channel message at a strange time".to_owned()));
-               }
-               if msg.common_fields.dust_limit_satoshis > 21000000 * 100000000 {
-                       return Err(ChannelError::close(format!("Peer never wants payout outputs? dust_limit_satoshis was {}", msg.common_fields.dust_limit_satoshis)));
-               }
-               if msg.channel_reserve_satoshis > self.context.channel_value_satoshis {
-                       return Err(ChannelError::close(format!("Bogus channel_reserve_satoshis ({}). Must not be greater than ({})", msg.channel_reserve_satoshis, self.context.channel_value_satoshis)));
-               }
-               if msg.common_fields.dust_limit_satoshis > self.context.holder_selected_channel_reserve_satoshis {
-                       return Err(ChannelError::close(format!("Dust limit ({}) is bigger than our channel reserve ({})", msg.common_fields.dust_limit_satoshis, self.context.holder_selected_channel_reserve_satoshis)));
-               }
-               if msg.channel_reserve_satoshis > self.context.channel_value_satoshis - self.context.holder_selected_channel_reserve_satoshis {
-                       return Err(ChannelError::close(format!("Bogus channel_reserve_satoshis ({}). Must not be greater than channel value minus our reserve ({})",
-                               msg.channel_reserve_satoshis, self.context.channel_value_satoshis - self.context.holder_selected_channel_reserve_satoshis)));
-               }
-               let full_channel_value_msat = (self.context.channel_value_satoshis - msg.channel_reserve_satoshis) * 1000;
-               if msg.common_fields.htlc_minimum_msat >= full_channel_value_msat {
-                       return Err(ChannelError::close(format!("Minimum htlc value ({}) is full channel value ({})", msg.common_fields.htlc_minimum_msat, full_channel_value_msat)));
-               }
-               let max_delay_acceptable = u16::min(peer_limits.their_to_self_delay, MAX_LOCAL_BREAKDOWN_TIMEOUT);
-               if msg.common_fields.to_self_delay > max_delay_acceptable {
-                       return Err(ChannelError::close(format!("They wanted our payments to be delayed by a needlessly long period. Upper limit: {}. Actual: {}", max_delay_acceptable, msg.common_fields.to_self_delay)));
-               }
-               if msg.common_fields.max_accepted_htlcs < 1 {
-                       return Err(ChannelError::close("0 max_accepted_htlcs makes for a useless channel".to_owned()));
-               }
-               if msg.common_fields.max_accepted_htlcs > MAX_HTLCS {
-                       return Err(ChannelError::close(format!("max_accepted_htlcs was {}. It must not be larger than {}", msg.common_fields.max_accepted_htlcs, MAX_HTLCS)));
-               }
-
-               // Now check against optional parameters as set by config...
-               if msg.common_fields.htlc_minimum_msat > peer_limits.max_htlc_minimum_msat {
-                       return Err(ChannelError::close(format!("htlc_minimum_msat ({}) is higher than the user specified limit ({})", msg.common_fields.htlc_minimum_msat, peer_limits.max_htlc_minimum_msat)));
-               }
-               if msg.common_fields.max_htlc_value_in_flight_msat < peer_limits.min_max_htlc_value_in_flight_msat {
-                       return Err(ChannelError::close(format!("max_htlc_value_in_flight_msat ({}) is less than the user specified limit ({})", msg.common_fields.max_htlc_value_in_flight_msat, peer_limits.min_max_htlc_value_in_flight_msat)));
-               }
-               if msg.channel_reserve_satoshis > peer_limits.max_channel_reserve_satoshis {
-                       return Err(ChannelError::close(format!("channel_reserve_satoshis ({}) is higher than the user specified limit ({})", msg.channel_reserve_satoshis, peer_limits.max_channel_reserve_satoshis)));
-               }
-               if msg.common_fields.max_accepted_htlcs < peer_limits.min_max_accepted_htlcs {
-                       return Err(ChannelError::close(format!("max_accepted_htlcs ({}) is less than the user specified limit ({})", msg.common_fields.max_accepted_htlcs, peer_limits.min_max_accepted_htlcs)));
-               }
-               if msg.common_fields.dust_limit_satoshis < MIN_CHAN_DUST_LIMIT_SATOSHIS {
-                       return Err(ChannelError::close(format!("dust_limit_satoshis ({}) is less than the implementation limit ({})", msg.common_fields.dust_limit_satoshis, MIN_CHAN_DUST_LIMIT_SATOSHIS)));
-               }
-               if msg.common_fields.dust_limit_satoshis > MAX_CHAN_DUST_LIMIT_SATOSHIS {
-                       return Err(ChannelError::close(format!("dust_limit_satoshis ({}) is greater than the implementation limit ({})", msg.common_fields.dust_limit_satoshis, MAX_CHAN_DUST_LIMIT_SATOSHIS)));
-               }
-               if msg.common_fields.minimum_depth > peer_limits.max_minimum_depth {
-                       return Err(ChannelError::close(format!("We consider the minimum depth to be unreasonably large. Expected minimum: ({}). Actual: ({})", peer_limits.max_minimum_depth, msg.common_fields.minimum_depth)));
-               }
-
-               if let Some(ty) = &msg.common_fields.channel_type {
-                       if *ty != self.context.channel_type {
-                               return Err(ChannelError::close("Channel Type in accept_channel didn't match the one sent in open_channel.".to_owned()));
-                       }
-               } else if their_features.supports_channel_type() {
-                       // Assume they've accepted the channel type as they said they understand it.
-               } else {
-                       let channel_type = ChannelTypeFeatures::from_init(&their_features);
-                       if channel_type != ChannelTypeFeatures::only_static_remote_key() {
-                               return Err(ChannelError::close("Only static_remote_key is supported for non-negotiated channel types".to_owned()));
-                       }
-                       self.context.channel_type = channel_type.clone();
-                       self.context.channel_transaction_parameters.channel_type_features = channel_type;
-               }
-
-               let counterparty_shutdown_scriptpubkey = if their_features.supports_upfront_shutdown_script() {
-                       match &msg.common_fields.shutdown_scriptpubkey {
-                               &Some(ref script) => {
-                                       // Peer is signaling upfront_shutdown and has opt-out with a 0-length script. We don't enforce anything
-                                       if script.len() == 0 {
-                                               None
-                                       } else {
-                                               if !script::is_bolt2_compliant(&script, their_features) {
-                                                       return Err(ChannelError::close(format!("Peer is signaling upfront_shutdown but has provided an unacceptable scriptpubkey format: {}", script)));
-                                               }
-                                               Some(script.clone())
-                                       }
-                               },
-                               // Peer is signaling upfront shutdown but don't opt-out with correct mechanism (a.k.a 0-length script). Peer looks buggy, we fail the channel
-                               &None => {
-                                       return Err(ChannelError::close("Peer is signaling upfront_shutdown but we don't get any script. Use 0-length script to opt-out".to_owned()));
-                               }
-                       }
-               } else { None };
-
-               self.context.counterparty_dust_limit_satoshis = msg.common_fields.dust_limit_satoshis;
-               self.context.counterparty_max_htlc_value_in_flight_msat = cmp::min(msg.common_fields.max_htlc_value_in_flight_msat, self.context.channel_value_satoshis * 1000);
-               self.context.counterparty_selected_channel_reserve_satoshis = Some(msg.channel_reserve_satoshis);
-               self.context.counterparty_htlc_minimum_msat = msg.common_fields.htlc_minimum_msat;
-               self.context.counterparty_max_accepted_htlcs = msg.common_fields.max_accepted_htlcs;
-
-               if peer_limits.trust_own_funding_0conf {
-                       self.context.minimum_depth = Some(msg.common_fields.minimum_depth);
-               } else {
-                       self.context.minimum_depth = Some(cmp::max(1, msg.common_fields.minimum_depth));
-               }
-
-               let counterparty_pubkeys = ChannelPublicKeys {
-                       funding_pubkey: msg.common_fields.funding_pubkey,
-                       revocation_basepoint: RevocationBasepoint::from(msg.common_fields.revocation_basepoint),
-                       payment_point: msg.common_fields.payment_basepoint,
-                       delayed_payment_basepoint: DelayedPaymentBasepoint::from(msg.common_fields.delayed_payment_basepoint),
-                       htlc_basepoint: HtlcBasepoint::from(msg.common_fields.htlc_basepoint)
-               };
-
-               self.context.channel_transaction_parameters.counterparty_parameters = Some(CounterpartyChannelTransactionParameters {
-                       selected_contest_delay: msg.common_fields.to_self_delay,
-                       pubkeys: counterparty_pubkeys,
-               });
-
-               self.context.counterparty_cur_commitment_point = Some(msg.common_fields.first_per_commitment_point);
-               self.context.counterparty_shutdown_scriptpubkey = counterparty_shutdown_scriptpubkey;
-
-               self.context.channel_state = ChannelState::NegotiatingFunding(
-                       NegotiatingFundingFlags::OUR_INIT_SENT | NegotiatingFundingFlags::THEIR_INIT_SENT
-               );
-               self.context.inbound_handshake_limits_override = None; // We're done enforcing limits on our peer's handshake now.
-
-               Ok(())
+       pub fn accept_channel(
+               &mut self, msg: &msgs::AcceptChannel, default_limits: &ChannelHandshakeLimits,
+               their_features: &InitFeatures
+       ) -> Result<(), ChannelError> {
+               self.context.do_accept_channel_checks(default_limits, their_features, &msg.common_fields, msg.channel_reserve_satoshis)
        }
 
        /// Handles a funding_signed message from the remote end.
@@ -7539,7 +7657,7 @@ impl<SP: Deref> OutboundV1Channel<SP> where SP::Target: SignerProvider {
                }
                if self.context.commitment_secrets.get_min_seen_secret() != (1 << 48) ||
                                self.context.cur_counterparty_commitment_transaction_number != INITIAL_COMMITMENT_NUMBER ||
-                               self.context.cur_holder_commitment_transaction_number != INITIAL_COMMITMENT_NUMBER {
+                               self.context.holder_commitment_point.transaction_number() != INITIAL_COMMITMENT_NUMBER {
                        panic!("Should not have advanced channel commitment tx numbers prior to funding_created");
                }
 
@@ -7553,8 +7671,8 @@ impl<SP: Deref> OutboundV1Channel<SP> where SP::Target: SignerProvider {
                log_trace!(logger, "Initial counterparty tx for channel {} is: txid {} tx {}",
                        &self.context.channel_id(), counterparty_initial_bitcoin_tx.txid, encode::serialize_hex(&counterparty_initial_bitcoin_tx.transaction));
 
-               let holder_signer = self.context.build_holder_transaction_keys(self.context.cur_holder_commitment_transaction_number);
-               let initial_commitment_tx = self.context.build_commitment_transaction(self.context.cur_holder_commitment_transaction_number, &holder_signer, true, false, logger).tx;
+               let holder_signer = self.context.build_holder_transaction_keys();
+               let initial_commitment_tx = self.context.build_commitment_transaction(self.context.holder_commitment_point.transaction_number(), &holder_signer, true, false, logger).tx;
                {
                        let trusted_tx = initial_commitment_tx.trust();
                        let initial_commitment_bitcoin_tx = trusted_tx.built_transaction();
@@ -7607,7 +7725,7 @@ impl<SP: Deref> OutboundV1Channel<SP> where SP::Target: SignerProvider {
                } else {
                        self.context.channel_state = ChannelState::AwaitingChannelReady(AwaitingChannelReadyFlags::new());
                }
-               self.context.cur_holder_commitment_transaction_number -= 1;
+               self.context.holder_commitment_point.advance(&self.context.holder_signer, &self.context.secp_ctx, logger);
                self.context.cur_counterparty_commitment_transaction_number -= 1;
 
                log_info!(logger, "Received funding_signed from peer for channel {}", &self.context.channel_id());
@@ -7618,7 +7736,7 @@ impl<SP: Deref> OutboundV1Channel<SP> where SP::Target: SignerProvider {
                        dual_funding_channel_context: None,
                };
 
-               let need_channel_ready = channel.check_get_channel_ready(0).is_some();
+               let need_channel_ready = channel.check_get_channel_ready(0, logger).is_some();
                channel.monitor_updating_paused(false, false, need_channel_ready, Vec::new(), Vec::new(), Vec::new());
                Ok((channel, channel_monitor))
        }
@@ -7743,7 +7861,7 @@ impl<SP: Deref> InboundV1Channel<SP> where SP::Target: SignerProvider {
                ) {
                        panic!("Tried to send accept_channel after channel had moved forward");
                }
-               if self.context.cur_holder_commitment_transaction_number != INITIAL_COMMITMENT_NUMBER {
+               if self.context.holder_commitment_point.transaction_number() != INITIAL_COMMITMENT_NUMBER {
                        panic!("Tried to send an accept_channel for a channel that has already advanced");
                }
 
@@ -7756,7 +7874,8 @@ impl<SP: Deref> InboundV1Channel<SP> where SP::Target: SignerProvider {
        ///
        /// [`msgs::AcceptChannel`]: crate::ln::msgs::AcceptChannel
        fn generate_accept_channel_message(&self) -> msgs::AcceptChannel {
-               let first_per_commitment_point = self.context.holder_signer.as_ref().get_per_commitment_point(self.context.cur_holder_commitment_transaction_number, &self.context.secp_ctx);
+               debug_assert!(self.context.holder_commitment_point.is_available());
+               let first_per_commitment_point = self.context.holder_commitment_point.current_point();
                let keys = self.context.get_holder_pubkeys();
 
                msgs::AcceptChannel {
@@ -7798,8 +7917,8 @@ impl<SP: Deref> InboundV1Channel<SP> where SP::Target: SignerProvider {
        fn check_funding_created_signature<L: Deref>(&mut self, sig: &Signature, logger: &L) -> Result<CommitmentTransaction, ChannelError> where L::Target: Logger {
                let funding_script = self.context.get_funding_redeemscript();
 
-               let keys = self.context.build_holder_transaction_keys(self.context.cur_holder_commitment_transaction_number);
-               let initial_commitment_tx = self.context.build_commitment_transaction(self.context.cur_holder_commitment_transaction_number, &keys, true, false, logger).tx;
+               let keys = self.context.build_holder_transaction_keys();
+               let initial_commitment_tx = self.context.build_commitment_transaction(self.context.holder_commitment_point.transaction_number(), &keys, true, false, logger).tx;
                let trusted_tx = initial_commitment_tx.trust();
                let initial_commitment_bitcoin_tx = trusted_tx.built_transaction();
                let sighash = initial_commitment_bitcoin_tx.get_sighash_all(&funding_script, self.context.channel_value_satoshis);
@@ -7833,7 +7952,7 @@ impl<SP: Deref> InboundV1Channel<SP> where SP::Target: SignerProvider {
                }
                if self.context.commitment_secrets.get_min_seen_secret() != (1 << 48) ||
                                self.context.cur_counterparty_commitment_transaction_number != INITIAL_COMMITMENT_NUMBER ||
-                               self.context.cur_holder_commitment_transaction_number != INITIAL_COMMITMENT_NUMBER {
+                               self.context.holder_commitment_point.transaction_number() != INITIAL_COMMITMENT_NUMBER {
                        panic!("Should not have advanced channel commitment tx numbers prior to funding_created");
                }
 
@@ -7873,7 +7992,7 @@ impl<SP: Deref> InboundV1Channel<SP> where SP::Target: SignerProvider {
                self.context.channel_state = ChannelState::AwaitingChannelReady(AwaitingChannelReadyFlags::new());
                self.context.channel_id = ChannelId::v1_from_funding_outpoint(funding_txo);
                self.context.cur_counterparty_commitment_transaction_number -= 1;
-               self.context.cur_holder_commitment_transaction_number -= 1;
+               self.context.holder_commitment_point.advance(&self.context.holder_signer, &self.context.secp_ctx, logger);
 
                let (counterparty_initial_commitment_tx, funding_signed) = self.context.get_funding_signed_msg(logger);
 
@@ -7907,7 +8026,7 @@ impl<SP: Deref> InboundV1Channel<SP> where SP::Target: SignerProvider {
                        #[cfg(any(dual_funding, splicing))]
                        dual_funding_channel_context: None,
                };
-               let need_channel_ready = channel.check_get_channel_ready(0).is_some();
+               let need_channel_ready = channel.check_get_channel_ready(0, logger).is_some();
                channel.monitor_updating_paused(false, false, need_channel_ready, Vec::new(), Vec::new(), Vec::new());
 
                Ok((channel, funding_signed, channel_monitor))
@@ -7994,15 +8113,15 @@ impl<SP: Deref> OutboundV2Channel<SP> where SP::Target: SignerProvider {
                        debug_assert!(false, "Cannot generate an open_channel2 after we've moved forward");
                }
 
-               if self.context.cur_holder_commitment_transaction_number != INITIAL_COMMITMENT_NUMBER {
+               if self.context.holder_commitment_point.transaction_number() != INITIAL_COMMITMENT_NUMBER {
                        debug_assert!(false, "Tried to send an open_channel2 for a channel that has already advanced");
                }
 
                let first_per_commitment_point = self.context.holder_signer.as_ref()
-                       .get_per_commitment_point(self.context.cur_holder_commitment_transaction_number,
+                       .get_per_commitment_point(self.context.holder_commitment_point.transaction_number(),
                                &self.context.secp_ctx);
                let second_per_commitment_point = self.context.holder_signer.as_ref()
-                       .get_per_commitment_point(self.context.cur_holder_commitment_transaction_number - 1,
+                       .get_per_commitment_point(self.context.holder_commitment_point.transaction_number() - 1,
                                &self.context.secp_ctx);
                let keys = self.context.get_holder_pubkeys();
 
@@ -8136,7 +8255,7 @@ impl<SP: Deref> InboundV2Channel<SP> where SP::Target: SignerProvider {
                ) {
                        debug_assert!(false, "Tried to send accept_channel2 after channel had moved forward");
                }
-               if self.context.cur_holder_commitment_transaction_number != INITIAL_COMMITMENT_NUMBER {
+               if self.context.holder_commitment_point.transaction_number() != INITIAL_COMMITMENT_NUMBER {
                        debug_assert!(false, "Tried to send an accept_channel2 for a channel that has already advanced");
                }
 
@@ -8150,9 +8269,9 @@ impl<SP: Deref> InboundV2Channel<SP> where SP::Target: SignerProvider {
        /// [`msgs::AcceptChannelV2`]: crate::ln::msgs::AcceptChannelV2
        fn generate_accept_channel_v2_message(&self) -> msgs::AcceptChannelV2 {
                let first_per_commitment_point = self.context.holder_signer.as_ref().get_per_commitment_point(
-                       self.context.cur_holder_commitment_transaction_number, &self.context.secp_ctx);
+                       self.context.holder_commitment_point.transaction_number(), &self.context.secp_ctx);
                let second_per_commitment_point = self.context.holder_signer.as_ref().get_per_commitment_point(
-                       self.context.cur_holder_commitment_transaction_number - 1, &self.context.secp_ctx);
+                       self.context.holder_commitment_point.transaction_number() - 1, &self.context.secp_ctx);
                let keys = self.context.get_holder_pubkeys();
 
                msgs::AcceptChannelV2 {
@@ -8325,7 +8444,7 @@ impl<SP: Deref> Writeable for Channel<SP> where SP::Target: SignerProvider {
                }
                self.context.destination_script.write(writer)?;
 
-               self.context.cur_holder_commitment_transaction_number.write(writer)?;
+               self.context.holder_commitment_point.transaction_number().write(writer)?;
                self.context.cur_counterparty_commitment_transaction_number.write(writer)?;
                self.context.value_to_self_msat.write(writer)?;
 
@@ -8599,6 +8718,10 @@ impl<SP: Deref> Writeable for Channel<SP> where SP::Target: SignerProvider {
                        monitor_pending_update_adds = Some(&self.context.monitor_pending_update_adds);
                }
 
+               // `current_point` will become optional when async signing is implemented.
+               let cur_holder_commitment_point = Some(self.context.holder_commitment_point.current_point());
+               let next_holder_commitment_point = self.context.holder_commitment_point.next_point();
+
                write_tlv_fields!(writer, {
                        (0, self.context.announcement_sigs, option),
                        // minimum_depth and counterparty_selected_channel_reserve_satoshis used to have a
@@ -8635,7 +8758,8 @@ impl<SP: Deref> Writeable for Channel<SP> where SP::Target: SignerProvider {
                        (39, pending_outbound_blinding_points, optional_vec),
                        (41, holding_cell_blinding_points, optional_vec),
                        (43, malformed_htlcs, optional_vec), // Added in 0.0.119
-                       // 45 and 47 are reserved for async signing
+                       (45, cur_holder_commitment_point, option),
+                       (47, next_holder_commitment_point, option),
                        (49, self.context.local_initiated_shutdown, option), // Added in 0.0.122
                });
 
@@ -8946,6 +9070,9 @@ impl<'a, 'b, 'c, ES: Deref, SP: Deref> ReadableArgs<(&'a ES, &'b SP, u32, &'c Ch
                let mut malformed_htlcs: Option<Vec<(u64, u16, [u8; 32])>> = None;
                let mut monitor_pending_update_adds: Option<Vec<msgs::UpdateAddHTLC>> = None;
 
+               let mut cur_holder_commitment_point_opt: Option<PublicKey> = None;
+               let mut next_holder_commitment_point_opt: Option<PublicKey> = None;
+
                read_tlv_fields!(reader, {
                        (0, announcement_sigs, option),
                        (1, minimum_depth, option),
@@ -8976,7 +9103,8 @@ impl<'a, 'b, 'c, ES: Deref, SP: Deref> ReadableArgs<(&'a ES, &'b SP, u32, &'c Ch
                        (39, pending_outbound_blinding_points_opt, optional_vec),
                        (41, holding_cell_blinding_points_opt, optional_vec),
                        (43, malformed_htlcs, optional_vec), // Added in 0.0.119
-                       // 45 and 47 are reserved for async signing
+                       (45, cur_holder_commitment_point_opt, option),
+                       (47, next_holder_commitment_point_opt, option),
                        (49, local_initiated_shutdown, option),
                });
 
@@ -9088,6 +9216,24 @@ impl<'a, 'b, 'c, ES: Deref, SP: Deref> ReadableArgs<(&'a ES, &'b SP, u32, &'c Ch
                        }
                }
 
+               // If we're restoring this channel for the first time after an upgrade, then we require that the
+               // signer be available so that we can immediately populate the current commitment point. Channel
+               // restoration will fail if this is not possible.
+               let holder_commitment_point = match (cur_holder_commitment_point_opt, next_holder_commitment_point_opt) {
+                       (Some(current), Some(next)) => HolderCommitmentPoint::Available {
+                               transaction_number: cur_holder_commitment_transaction_number, current, next
+                       },
+                       (Some(current), _) => HolderCommitmentPoint::Available {
+                               transaction_number: cur_holder_commitment_transaction_number, current,
+                               next: holder_signer.get_per_commitment_point(cur_holder_commitment_transaction_number - 1, &secp_ctx),
+                       },
+                       (_, _) => HolderCommitmentPoint::Available {
+                               transaction_number: cur_holder_commitment_transaction_number,
+                               current: holder_signer.get_per_commitment_point(cur_holder_commitment_transaction_number, &secp_ctx),
+                               next: holder_signer.get_per_commitment_point(cur_holder_commitment_transaction_number - 1, &secp_ctx),
+                       },
+               };
+
                Ok(Channel {
                        context: ChannelContext {
                                user_id,
@@ -9113,7 +9259,7 @@ impl<'a, 'b, 'c, ES: Deref, SP: Deref> ReadableArgs<(&'a ES, &'b SP, u32, &'c Ch
                                shutdown_scriptpubkey,
                                destination_script,
 
-                               cur_holder_commitment_transaction_number,
+                               holder_commitment_point,
                                cur_counterparty_commitment_transaction_number,
                                value_to_self_msat,
 
@@ -10987,6 +11133,6 @@ mod tests {
                // Clear the ChannelState::WaitingForBatch only when called by ChannelManager.
                node_a_chan.set_batch_ready();
                assert_eq!(node_a_chan.context.channel_state, ChannelState::AwaitingChannelReady(AwaitingChannelReadyFlags::THEIR_CHANNEL_READY));
-               assert!(node_a_chan.check_get_channel_ready(0).is_some());
+               assert!(node_a_chan.check_get_channel_ready(0, &&logger).is_some());
        }
 }