Decode update_add_htlc onions before forwarding HTLCs
[rust-lightning] / lightning / src / ln / channelmanager.rs
index 87ac05ccb2b905e262f5b32cff5354515a75ba08..28513ebbc9ec921abc4bc539a98ff1d288fe0386 100644 (file)
@@ -58,10 +58,11 @@ use crate::ln::msgs::{ChannelMessageHandler, DecodeError, LightningError};
 use crate::ln::outbound_payment;
 use crate::ln::outbound_payment::{Bolt12PaymentError, OutboundPayments, PaymentAttempts, PendingOutboundPayment, SendAlongPathArgs, StaleExpiration};
 use crate::ln::wire::Encode;
-use crate::offers::invoice::{BlindedPayInfo, Bolt12Invoice, DEFAULT_RELATIVE_EXPIRY, DerivedSigningPubkey, InvoiceBuilder};
+use crate::offers::invoice::{BlindedPayInfo, Bolt12Invoice, DEFAULT_RELATIVE_EXPIRY, DerivedSigningPubkey, ExplicitSigningPubkey, InvoiceBuilder, UnsignedBolt12Invoice};
 use crate::offers::invoice_error::InvoiceError;
+use crate::offers::invoice_request::{DerivedPayerId, InvoiceRequestBuilder};
 use crate::offers::merkle::SignError;
-use crate::offers::offer::{DerivedMetadata, Offer, OfferBuilder};
+use crate::offers::offer::{Offer, OfferBuilder};
 use crate::offers::parse::Bolt12SemanticError;
 use crate::offers::refund::{Refund, RefundBuilder};
 use crate::onion_message::messenger::{Destination, MessageRouter, PendingOnionMessage, new_pending_onion_message};
@@ -77,11 +78,17 @@ use crate::util::logger::{Level, Logger, WithContext};
 use crate::util::errors::APIError;
 #[cfg(not(c_bindings))]
 use {
+       crate::offers::offer::DerivedMetadata,
        crate::routing::router::DefaultRouter,
        crate::routing::gossip::NetworkGraph,
        crate::routing::scoring::{ProbabilisticScorer, ProbabilisticScoringFeeParameters},
        crate::sign::KeysManager,
 };
+#[cfg(c_bindings)]
+use {
+       crate::offers::offer::OfferWithDerivedMetadataBuilder,
+       crate::offers::refund::RefundMaybeWithDerivedMetadataBuilder,
+};
 
 use alloc::collections::{btree_map, BTreeMap};
 
@@ -193,6 +200,8 @@ pub enum PendingHTLCRouting {
                /// For HTLCs received by LDK, these will ultimately bubble back up as
                /// [`RecipientOnionFields::custom_tlvs`].
                custom_tlvs: Vec<(u64, Vec<u8>)>,
+               /// Set if this HTLC is the final hop in a multi-hop blinded path.
+               requires_blinded_error: bool,
        },
 }
 
@@ -214,6 +223,7 @@ impl PendingHTLCRouting {
                match self {
                        Self::Forward { blinded: Some(BlindedForward { failure, .. }), .. } => Some(*failure),
                        Self::Receive { requires_blinded_error: true, .. } => Some(BlindedFailure::FromBlindedNode),
+                       Self::ReceiveKeysend { requires_blinded_error: true, .. } => Some(BlindedFailure::FromBlindedNode),
                        _ => None,
                }
        }
@@ -905,7 +915,14 @@ impl <SP: Deref> PeerState<SP> where SP::Target: SignerProvider {
                        return false
                }
                !self.channel_by_id.iter().any(|(_, phase)|
-                       matches!(phase, ChannelPhase::Funded(_) | ChannelPhase::UnfundedOutboundV1(_))
+                       match phase {
+                               ChannelPhase::Funded(_) | ChannelPhase::UnfundedOutboundV1(_) => true,
+                               ChannelPhase::UnfundedInboundV1(_) => false,
+                               #[cfg(dual_funding)]
+                               ChannelPhase::UnfundedOutboundV2(_) => true,
+                               #[cfg(dual_funding)]
+                               ChannelPhase::UnfundedInboundV2(_) => false,
+                       }
                )
                        && self.monitor_update_blocked_actions.is_empty()
                        && self.in_flight_monitor_updates.is_empty()
@@ -1164,6 +1181,8 @@ where
 //  |   |
 //  |   |__`pending_intercepted_htlcs`
 //  |
+//  |__`decode_update_add_htlcs`
+//  |
 //  |__`per_peer_state`
 //      |
 //      |__`pending_inbound_payments`
@@ -1254,6 +1273,18 @@ where
        /// See `ChannelManager` struct-level documentation for lock order requirements.
        pending_intercepted_htlcs: Mutex<HashMap<InterceptId, PendingAddHTLCInfo>>,
 
+       /// SCID/SCID Alias -> pending `update_add_htlc`s to decode.
+       ///
+       /// Note that because we may have an SCID Alias as the key we can have two entries per channel,
+       /// though in practice we probably won't be receiving HTLCs for a channel both via the alias
+       /// and via the classic SCID.
+       ///
+       /// Note that no consistency guarantees are made about the existence of a channel with the
+       /// `short_channel_id` here, nor the `channel_id` in `UpdateAddHTLC`!
+       ///
+       /// See `ChannelManager` struct-level documentation for lock order requirements.
+       decode_update_add_htlcs: Mutex<HashMap<u64, Vec<msgs::UpdateAddHTLC>>>,
+
        /// The sets of payments which are claimable or currently being claimed. See
        /// [`ClaimablePayments`]' individual field docs for more info.
        ///
@@ -2092,6 +2123,14 @@ macro_rules! convert_chan_phase_err {
                        ChannelPhase::UnfundedInboundV1(channel) => {
                                convert_chan_phase_err!($self, $err, channel, $channel_id, UNFUNDED_CHANNEL)
                        },
+                       #[cfg(dual_funding)]
+                       ChannelPhase::UnfundedOutboundV2(channel) => {
+                               convert_chan_phase_err!($self, $err, channel, $channel_id, UNFUNDED_CHANNEL)
+                       },
+                       #[cfg(dual_funding)]
+                       ChannelPhase::UnfundedInboundV2(channel) => {
+                               convert_chan_phase_err!($self, $err, channel, $channel_id, UNFUNDED_CHANNEL)
+                       },
                }
        };
 }
@@ -2194,7 +2233,7 @@ macro_rules! handle_monitor_update_completion {
                let logger = WithChannelContext::from(&$self.logger, &$chan.context);
                let mut updates = $chan.monitor_updating_restored(&&logger,
                        &$self.node_signer, $self.chain_hash, &$self.default_configuration,
-                       $self.best_block.read().unwrap().height());
+                       $self.best_block.read().unwrap().height);
                let counterparty_node_id = $chan.context.get_counterparty_node_id();
                let channel_update = if updates.channel_ready.is_some() && $chan.context.is_usable() {
                        // We only send a channel_update in the case where we are just now sending a
@@ -2213,9 +2252,9 @@ macro_rules! handle_monitor_update_completion {
                let update_actions = $peer_state.monitor_update_blocked_actions
                        .remove(&$chan.context.channel_id()).unwrap_or(Vec::new());
 
-               let htlc_forwards = $self.handle_channel_resumption(
+               let (htlc_forwards, decode_update_add_htlcs) = $self.handle_channel_resumption(
                        &mut $peer_state.pending_msg_events, $chan, updates.raa,
-                       updates.commitment_update, updates.order, updates.accepted_htlcs,
+                       updates.commitment_update, updates.order, updates.accepted_htlcs, updates.pending_update_adds,
                        updates.funding_broadcastable, updates.channel_ready,
                        updates.announcement_sigs);
                if let Some(upd) = channel_update {
@@ -2276,6 +2315,9 @@ macro_rules! handle_monitor_update_completion {
                if let Some(forwards) = htlc_forwards {
                        $self.forward_htlcs(&mut [forwards][..]);
                }
+               if let Some(decode) = decode_update_add_htlcs {
+                       $self.push_decode_update_add_htlcs(decode);
+               }
                $self.finalize_claims(updates.finalized_claimed_htlcs);
                for failure in updates.failed_htlcs.drain(..) {
                        let receiver = HTLCDestination::NextHopChannel { node_id: Some(counterparty_node_id), channel_id };
@@ -2452,6 +2494,7 @@ where
                        pending_inbound_payments: Mutex::new(new_hash_map()),
                        pending_outbound_payments: OutboundPayments::new(),
                        forward_htlcs: Mutex::new(new_hash_map()),
+                       decode_update_add_htlcs: Mutex::new(new_hash_map()),
                        claimable_payments: Mutex::new(ClaimablePayments { claimable_payments: new_hash_map(), pending_claiming_payments: new_hash_map() }),
                        pending_intercepted_htlcs: Mutex::new(new_hash_map()),
                        outpoint_to_peer: Mutex::new(new_hash_map()),
@@ -2494,7 +2537,7 @@ where
        }
 
        fn create_and_insert_outbound_scid_alias(&self) -> u64 {
-               let height = self.best_block.read().unwrap().height();
+               let height = self.best_block.read().unwrap().height;
                let mut outbound_scid_alias = 0;
                let mut i = 0;
                loop {
@@ -2572,7 +2615,7 @@ where
                        let config = if override_config.is_some() { override_config.as_ref().unwrap() } else { &self.default_configuration };
                        match OutboundV1Channel::new(&self.fee_estimator, &self.entropy_source, &self.signer_provider, their_network_key,
                                their_features, channel_value_satoshis, push_msat, user_channel_id, config,
-                               self.best_block.read().unwrap().height(), outbound_scid_alias, temporary_channel_id)
+                               self.best_block.read().unwrap().height, outbound_scid_alias, temporary_channel_id)
                        {
                                Ok(res) => res,
                                Err(e) => {
@@ -2611,7 +2654,7 @@ where
                // the same channel.
                let mut res = Vec::with_capacity(self.short_to_chan_info.read().unwrap().len());
                {
-                       let best_block_height = self.best_block.read().unwrap().height();
+                       let best_block_height = self.best_block.read().unwrap().height;
                        let per_peer_state = self.per_peer_state.read().unwrap();
                        for (_cp_id, peer_state_mutex) in per_peer_state.iter() {
                                let mut peer_state_lock = peer_state_mutex.lock().unwrap();
@@ -2644,7 +2687,7 @@ where
                // the same channel.
                let mut res = Vec::with_capacity(self.short_to_chan_info.read().unwrap().len());
                {
-                       let best_block_height = self.best_block.read().unwrap().height();
+                       let best_block_height = self.best_block.read().unwrap().height;
                        let per_peer_state = self.per_peer_state.read().unwrap();
                        for (_cp_id, peer_state_mutex) in per_peer_state.iter() {
                                let mut peer_state_lock = peer_state_mutex.lock().unwrap();
@@ -2674,7 +2717,7 @@ where
 
        /// Gets the list of channels we have with a given counterparty, in random order.
        pub fn list_channels_with_counterparty(&self, counterparty_node_id: &PublicKey) -> Vec<ChannelDetails> {
-               let best_block_height = self.best_block.read().unwrap().height();
+               let best_block_height = self.best_block.read().unwrap().height;
                let per_peer_state = self.per_peer_state.read().unwrap();
 
                if let Some(peer_state_mutex) = per_peer_state.get(counterparty_node_id) {
@@ -2958,6 +3001,13 @@ where
                                                // Unfunded channel has no update
                                                (None, chan_phase.context().get_counterparty_node_id())
                                        },
+                                       // TODO(dual_funding): Combine this match arm with above once #[cfg(dual_funding)] is removed.
+                                       #[cfg(dual_funding)]
+                                       ChannelPhase::UnfundedOutboundV2(_) | ChannelPhase::UnfundedInboundV2(_) => {
+                                               self.finish_close_channel(chan_phase.context_mut().force_shutdown(false, closure_reason));
+                                               // Unfunded channel has no update
+                                               (None, chan_phase.context().get_counterparty_node_id())
+                                       },
                                }
                        } else if peer_state.inbound_channel_request_by_id.remove(channel_id).is_some() {
                                log_error!(logger, "Force-closing channel {}", &channel_id);
@@ -3021,8 +3071,8 @@ where
        /// the latest local transaction(s). Fails if `channel_id` is unknown to the manager, or if the
        /// `counterparty_node_id` isn't the counterparty of the corresponding channel.
        ///
-       /// You can always get the latest local transaction(s) to broadcast from
-       /// [`ChannelMonitor::get_latest_holder_commitment_txn`].
+       /// You can always broadcast the latest local transaction(s) via
+       /// [`ChannelMonitor::broadcast_latest_holder_commitment_txn`].
        pub fn force_close_without_broadcasting_txn(&self, channel_id: &ChannelId, counterparty_node_id: &PublicKey)
        -> Result<(), APIError> {
                self.force_close_sending_error(channel_id, counterparty_node_id, false)
@@ -3044,6 +3094,163 @@ where
                }
        }
 
+       fn can_forward_htlc_to_outgoing_channel(
+               &self, chan: &mut Channel<SP>, msg: &msgs::UpdateAddHTLC, next_packet: &NextPacketDetails
+       ) -> Result<(), (&'static str, u16, Option<msgs::ChannelUpdate>)> {
+               if !chan.context.should_announce() && !self.default_configuration.accept_forwards_to_priv_channels {
+                       // Note that the behavior here should be identical to the above block - we
+                       // should NOT reveal the existence or non-existence of a private channel if
+                       // we don't allow forwards outbound over them.
+                       return Err(("Refusing to forward to a private channel based on our config.", 0x4000 | 10, None));
+               }
+               if chan.context.get_channel_type().supports_scid_privacy() && next_packet.outgoing_scid != chan.context.outbound_scid_alias() {
+                       // `option_scid_alias` (referred to in LDK as `scid_privacy`) means
+                       // "refuse to forward unless the SCID alias was used", so we pretend
+                       // we don't have the channel here.
+                       return Err(("Refusing to forward over real channel SCID as our counterparty requested.", 0x4000 | 10, None));
+               }
+
+               // Note that we could technically not return an error yet here and just hope
+               // that the connection is reestablished or monitor updated by the time we get
+               // around to doing the actual forward, but better to fail early if we can and
+               // hopefully an attacker trying to path-trace payments cannot make this occur
+               // on a small/per-node/per-channel scale.
+               if !chan.context.is_live() { // channel_disabled
+                       // If the channel_update we're going to return is disabled (i.e. the
+                       // peer has been disabled for some time), return `channel_disabled`,
+                       // otherwise return `temporary_channel_failure`.
+                       let chan_update_opt = self.get_channel_update_for_onion(next_packet.outgoing_scid, chan).ok();
+                       if chan_update_opt.as_ref().map(|u| u.contents.flags & 2 == 2).unwrap_or(false) {
+                               return Err(("Forwarding channel has been disconnected for some time.", 0x1000 | 20, chan_update_opt));
+                       } else {
+                               return Err(("Forwarding channel is not in a ready state.", 0x1000 | 7, chan_update_opt));
+                       }
+               }
+               if next_packet.outgoing_amt_msat < chan.context.get_counterparty_htlc_minimum_msat() { // amount_below_minimum
+                       let chan_update_opt = self.get_channel_update_for_onion(next_packet.outgoing_scid, chan).ok();
+                       return Err(("HTLC amount was below the htlc_minimum_msat", 0x1000 | 11, chan_update_opt));
+               }
+               if let Err((err, code)) = chan.htlc_satisfies_config(msg, next_packet.outgoing_amt_msat, next_packet.outgoing_cltv_value) {
+                       let chan_update_opt = self.get_channel_update_for_onion(next_packet.outgoing_scid, chan).ok();
+                       return Err((err, code, chan_update_opt));
+               }
+
+               Ok(())
+       }
+
+       /// Executes a callback `C` that returns some value `X` on the channel found with the given
+       /// `scid`. `None` is returned when the channel is not found.
+       fn do_funded_channel_callback<X, C: Fn(&mut Channel<SP>) -> X>(
+               &self, scid: u64, callback: C,
+       ) -> Option<X> {
+               let (counterparty_node_id, channel_id) = match self.short_to_chan_info.read().unwrap().get(&scid).cloned() {
+                       None => return None,
+                       Some((cp_id, id)) => (cp_id, id),
+               };
+               let per_peer_state = self.per_peer_state.read().unwrap();
+               let peer_state_mutex_opt = per_peer_state.get(&counterparty_node_id);
+               if peer_state_mutex_opt.is_none() {
+                       return None;
+               }
+               let mut peer_state_lock = peer_state_mutex_opt.unwrap().lock().unwrap();
+               let peer_state = &mut *peer_state_lock;
+               match peer_state.channel_by_id.get_mut(&channel_id).and_then(
+                       |chan_phase| if let ChannelPhase::Funded(chan) = chan_phase { Some(chan) } else { None }
+               ) {
+                       None => None,
+                       Some(chan) => Some(callback(chan)),
+               }
+       }
+
+       fn can_forward_htlc(
+               &self, msg: &msgs::UpdateAddHTLC, next_packet_details: &NextPacketDetails
+       ) -> Result<(), (&'static str, u16, Option<msgs::ChannelUpdate>)> {
+               match self.do_funded_channel_callback(next_packet_details.outgoing_scid, |chan: &mut Channel<SP>| {
+                       self.can_forward_htlc_to_outgoing_channel(chan, msg, next_packet_details)
+               }) {
+                       Some(Ok(())) => {},
+                       Some(Err(e)) => return Err(e),
+                       None => {
+                               // If we couldn't find the channel info for the scid, it may be a phantom or
+                               // intercept forward.
+                               if (self.default_configuration.accept_intercept_htlcs &&
+                                       fake_scid::is_valid_intercept(&self.fake_scid_rand_bytes, next_packet_details.outgoing_scid, &self.chain_hash)) ||
+                                       fake_scid::is_valid_phantom(&self.fake_scid_rand_bytes, next_packet_details.outgoing_scid, &self.chain_hash)
+                               {} else {
+                                       return Err(("Don't have available channel for forwarding as requested.", 0x4000 | 10, None));
+                               }
+                       }
+               }
+
+               let cur_height = self.best_block.read().unwrap().height + 1;
+               if let Err((err_msg, err_code)) = check_incoming_htlc_cltv(
+                       cur_height, next_packet_details.outgoing_cltv_value, msg.cltv_expiry
+               ) {
+                       let chan_update_opt = self.do_funded_channel_callback(next_packet_details.outgoing_scid, |chan: &mut Channel<SP>| {
+                               self.get_channel_update_for_onion(next_packet_details.outgoing_scid, chan).ok()
+                       }).flatten();
+                       return Err((err_msg, err_code, chan_update_opt));
+               }
+
+               Ok(())
+       }
+
+       fn htlc_failure_from_update_add_err(
+               &self, msg: &msgs::UpdateAddHTLC, counterparty_node_id: &PublicKey, err_msg: &'static str,
+               mut err_code: u16, chan_update: Option<msgs::ChannelUpdate>, is_intro_node_blinded_forward: bool,
+               shared_secret: &[u8; 32]
+       ) -> HTLCFailureMsg {
+               let mut res = VecWriter(Vec::with_capacity(chan_update.serialized_length() + 2 + 8 + 2));
+               if chan_update.is_some() && err_code & 0x1000 == 0x1000 {
+                       let chan_update = chan_update.unwrap();
+                       if err_code == 0x1000 | 11 || err_code == 0x1000 | 12 {
+                               msg.amount_msat.write(&mut res).expect("Writes cannot fail");
+                       }
+                       else if err_code == 0x1000 | 13 {
+                               msg.cltv_expiry.write(&mut res).expect("Writes cannot fail");
+                       }
+                       else if err_code == 0x1000 | 20 {
+                               // TODO: underspecified, follow https://github.com/lightning/bolts/issues/791
+                               0u16.write(&mut res).expect("Writes cannot fail");
+                       }
+                       (chan_update.serialized_length() as u16 + 2).write(&mut res).expect("Writes cannot fail");
+                       msgs::ChannelUpdate::TYPE.write(&mut res).expect("Writes cannot fail");
+                       chan_update.write(&mut res).expect("Writes cannot fail");
+               } else if err_code & 0x1000 == 0x1000 {
+                       // If we're trying to return an error that requires a `channel_update` but
+                       // we're forwarding to a phantom or intercept "channel" (i.e. cannot
+                       // generate an update), just use the generic "temporary_node_failure"
+                       // instead.
+                       err_code = 0x2000 | 2;
+               }
+
+               log_info!(
+                       WithContext::from(&self.logger, Some(*counterparty_node_id), Some(msg.channel_id)),
+                       "Failed to accept/forward incoming HTLC: {}", err_msg
+               );
+               // If `msg.blinding_point` is set, we must always fail with malformed.
+               if msg.blinding_point.is_some() {
+                       return HTLCFailureMsg::Malformed(msgs::UpdateFailMalformedHTLC {
+                               channel_id: msg.channel_id,
+                               htlc_id: msg.htlc_id,
+                               sha256_of_onion: [0; 32],
+                               failure_code: INVALID_ONION_BLINDING,
+                       });
+               }
+
+               let (err_code, err_data) = if is_intro_node_blinded_forward {
+                       (INVALID_ONION_BLINDING, &[0; 32][..])
+               } else {
+                       (err_code, &res.0[..])
+               };
+               HTLCFailureMsg::Relay(msgs::UpdateFailHTLC {
+                       channel_id: msg.channel_id,
+                       htlc_id: msg.htlc_id,
+                       reason: HTLCFailReason::reason(err_code, err_data.to_vec())
+                               .get_encrypted_failure_packet(shared_secret, &None),
+               })
+       }
+
        fn decode_update_add_htlc_onion(
                &self, msg: &msgs::UpdateAddHTLC, counterparty_node_id: &PublicKey,
        ) -> Result<
@@ -3053,48 +3260,7 @@ where
                        msg, &self.node_signer, &self.logger, &self.secp_ctx
                )?;
 
-               let is_intro_node_forward = match next_hop {
-                       onion_utils::Hop::Forward {
-                               next_hop_data: msgs::InboundOnionPayload::BlindedForward {
-                                       intro_node_blinding_point: Some(_), ..
-                               }, ..
-                       } => true,
-                       _ => false,
-               };
-
-               macro_rules! return_err {
-                       ($msg: expr, $err_code: expr, $data: expr) => {
-                               {
-                                       log_info!(
-                                               WithContext::from(&self.logger, Some(*counterparty_node_id), Some(msg.channel_id)),
-                                               "Failed to accept/forward incoming HTLC: {}", $msg
-                                       );
-                                       // If `msg.blinding_point` is set, we must always fail with malformed.
-                                       if msg.blinding_point.is_some() {
-                                               return Err(HTLCFailureMsg::Malformed(msgs::UpdateFailMalformedHTLC {
-                                                       channel_id: msg.channel_id,
-                                                       htlc_id: msg.htlc_id,
-                                                       sha256_of_onion: [0; 32],
-                                                       failure_code: INVALID_ONION_BLINDING,
-                                               }));
-                                       }
-
-                                       let (err_code, err_data) = if is_intro_node_forward {
-                                               (INVALID_ONION_BLINDING, &[0; 32][..])
-                                       } else { ($err_code, $data) };
-                                       return Err(HTLCFailureMsg::Relay(msgs::UpdateFailHTLC {
-                                               channel_id: msg.channel_id,
-                                               htlc_id: msg.htlc_id,
-                                               reason: HTLCFailReason::reason(err_code, err_data.to_vec())
-                                                       .get_encrypted_failure_packet(&shared_secret, &None),
-                                       }));
-                               }
-                       }
-               }
-
-               let NextPacketDetails {
-                       next_packet_pubkey, outgoing_amt_msat, outgoing_scid, outgoing_cltv_value
-               } = match next_packet_details_opt {
+               let next_packet_details = match next_packet_details_opt {
                        Some(next_packet_details) => next_packet_details,
                        // it is a receive, so no need for outbound checks
                        None => return Ok((next_hop, shared_secret, None)),
@@ -3102,124 +3268,15 @@ where
 
                // Perform outbound checks here instead of in [`Self::construct_pending_htlc_info`] because we
                // can't hold the outbound peer state lock at the same time as the inbound peer state lock.
-               if let Some((err, mut code, chan_update)) = loop {
-                       let id_option = self.short_to_chan_info.read().unwrap().get(&outgoing_scid).cloned();
-                       let forwarding_chan_info_opt = match id_option {
-                               None => { // unknown_next_peer
-                                       // Note that this is likely a timing oracle for detecting whether an scid is a
-                                       // phantom or an intercept.
-                                       if (self.default_configuration.accept_intercept_htlcs &&
-                                               fake_scid::is_valid_intercept(&self.fake_scid_rand_bytes, outgoing_scid, &self.chain_hash)) ||
-                                               fake_scid::is_valid_phantom(&self.fake_scid_rand_bytes, outgoing_scid, &self.chain_hash)
-                                       {
-                                               None
-                                       } else {
-                                               break Some(("Don't have available channel for forwarding as requested.", 0x4000 | 10, None));
-                                       }
-                               },
-                               Some((cp_id, id)) => Some((cp_id.clone(), id.clone())),
-                       };
-                       let chan_update_opt = if let Some((counterparty_node_id, forwarding_id)) = forwarding_chan_info_opt {
-                               let per_peer_state = self.per_peer_state.read().unwrap();
-                               let peer_state_mutex_opt = per_peer_state.get(&counterparty_node_id);
-                               if peer_state_mutex_opt.is_none() {
-                                       break Some(("Don't have available channel for forwarding as requested.", 0x4000 | 10, None));
-                               }
-                               let mut peer_state_lock = peer_state_mutex_opt.unwrap().lock().unwrap();
-                               let peer_state = &mut *peer_state_lock;
-                               let chan = match peer_state.channel_by_id.get_mut(&forwarding_id).map(
-                                       |chan_phase| if let ChannelPhase::Funded(chan) = chan_phase { Some(chan) } else { None }
-                               ).flatten() {
-                                       None => {
-                                               // Channel was removed. The short_to_chan_info and channel_by_id maps
-                                               // have no consistency guarantees.
-                                               break Some(("Don't have available channel for forwarding as requested.", 0x4000 | 10, None));
-                                       },
-                                       Some(chan) => chan
-                               };
-                               if !chan.context.should_announce() && !self.default_configuration.accept_forwards_to_priv_channels {
-                                       // Note that the behavior here should be identical to the above block - we
-                                       // should NOT reveal the existence or non-existence of a private channel if
-                                       // we don't allow forwards outbound over them.
-                                       break Some(("Refusing to forward to a private channel based on our config.", 0x4000 | 10, None));
-                               }
-                               if chan.context.get_channel_type().supports_scid_privacy() && outgoing_scid != chan.context.outbound_scid_alias() {
-                                       // `option_scid_alias` (referred to in LDK as `scid_privacy`) means
-                                       // "refuse to forward unless the SCID alias was used", so we pretend
-                                       // we don't have the channel here.
-                                       break Some(("Refusing to forward over real channel SCID as our counterparty requested.", 0x4000 | 10, None));
-                               }
-                               let chan_update_opt = self.get_channel_update_for_onion(outgoing_scid, chan).ok();
-
-                               // Note that we could technically not return an error yet here and just hope
-                               // that the connection is reestablished or monitor updated by the time we get
-                               // around to doing the actual forward, but better to fail early if we can and
-                               // hopefully an attacker trying to path-trace payments cannot make this occur
-                               // on a small/per-node/per-channel scale.
-                               if !chan.context.is_live() { // channel_disabled
-                                       // If the channel_update we're going to return is disabled (i.e. the
-                                       // peer has been disabled for some time), return `channel_disabled`,
-                                       // otherwise return `temporary_channel_failure`.
-                                       if chan_update_opt.as_ref().map(|u| u.contents.flags & 2 == 2).unwrap_or(false) {
-                                               break Some(("Forwarding channel has been disconnected for some time.", 0x1000 | 20, chan_update_opt));
-                                       } else {
-                                               break Some(("Forwarding channel is not in a ready state.", 0x1000 | 7, chan_update_opt));
-                                       }
-                               }
-                               if outgoing_amt_msat < chan.context.get_counterparty_htlc_minimum_msat() { // amount_below_minimum
-                                       break Some(("HTLC amount was below the htlc_minimum_msat", 0x1000 | 11, chan_update_opt));
-                               }
-                               if let Err((err, code)) = chan.htlc_satisfies_config(&msg, outgoing_amt_msat, outgoing_cltv_value) {
-                                       break Some((err, code, chan_update_opt));
-                               }
-                               chan_update_opt
-                       } else {
-                               None
-                       };
-
-                       let cur_height = self.best_block.read().unwrap().height() + 1;
-
-                       if let Err((err_msg, code)) = check_incoming_htlc_cltv(
-                               cur_height, outgoing_cltv_value, msg.cltv_expiry
-                       ) {
-                               if code & 0x1000 != 0 && chan_update_opt.is_none() {
-                                       // We really should set `incorrect_cltv_expiry` here but as we're not
-                                       // forwarding over a real channel we can't generate a channel_update
-                                       // for it. Instead we just return a generic temporary_node_failure.
-                                       break Some((err_msg, 0x2000 | 2, None))
-                               }
-                               let chan_update_opt = if code & 0x1000 != 0 { chan_update_opt } else { None };
-                               break Some((err_msg, code, chan_update_opt));
-                       }
+               self.can_forward_htlc(&msg, &next_packet_details).map_err(|e| {
+                       let (err_msg, err_code, chan_update_opt) = e;
+                       self.htlc_failure_from_update_add_err(
+                               msg, counterparty_node_id, err_msg, err_code, chan_update_opt,
+                               next_hop.is_intro_node_blinded_forward(), &shared_secret
+                       )
+               })?;
 
-                       break None;
-               }
-               {
-                       let mut res = VecWriter(Vec::with_capacity(chan_update.serialized_length() + 2 + 8 + 2));
-                       if let Some(chan_update) = chan_update {
-                               if code == 0x1000 | 11 || code == 0x1000 | 12 {
-                                       msg.amount_msat.write(&mut res).expect("Writes cannot fail");
-                               }
-                               else if code == 0x1000 | 13 {
-                                       msg.cltv_expiry.write(&mut res).expect("Writes cannot fail");
-                               }
-                               else if code == 0x1000 | 20 {
-                                       // TODO: underspecified, follow https://github.com/lightning/bolts/issues/791
-                                       0u16.write(&mut res).expect("Writes cannot fail");
-                               }
-                               (chan_update.serialized_length() as u16 + 2).write(&mut res).expect("Writes cannot fail");
-                               msgs::ChannelUpdate::TYPE.write(&mut res).expect("Writes cannot fail");
-                               chan_update.write(&mut res).expect("Writes cannot fail");
-                       } else if code & 0x1000 == 0x1000 {
-                               // If we're trying to return an error that requires a `channel_update` but
-                               // we're forwarding to a phantom or intercept "channel" (i.e. cannot
-                               // generate an update), just use the generic "temporary_node_failure"
-                               // instead.
-                               code = 0x2000 | 2;
-                       }
-                       return_err!(err, code, &res.0[..]);
-               }
-               Ok((next_hop, shared_secret, Some(next_packet_pubkey)))
+               Ok((next_hop, shared_secret, Some(next_packet_details.next_packet_pubkey)))
        }
 
        fn construct_pending_htlc_status<'a>(
@@ -3254,7 +3311,7 @@ where
                match decoded_hop {
                        onion_utils::Hop::Receive(next_hop_data) => {
                                // OUR PAYMENT!
-                               let current_height: u32 = self.best_block.read().unwrap().height();
+                               let current_height: u32 = self.best_block.read().unwrap().height;
                                match create_recv_pending_htlc_info(next_hop_data, shared_secret, msg.payment_hash,
                                        msg.amount_msat, msg.cltv_expiry, None, allow_underpay, msg.skimmed_fee_msat,
                                        current_height, self.default_configuration.accept_mpp_keysend)
@@ -3514,7 +3571,7 @@ where
        /// [`PeerManager::process_events`]: crate::ln::peer_handler::PeerManager::process_events
        /// [`ChannelMonitorUpdateStatus::InProgress`]: crate::chain::ChannelMonitorUpdateStatus::InProgress
        pub fn send_payment_with_route(&self, route: &Route, payment_hash: PaymentHash, recipient_onion: RecipientOnionFields, payment_id: PaymentId) -> Result<(), PaymentSendFailure> {
-               let best_block_height = self.best_block.read().unwrap().height();
+               let best_block_height = self.best_block.read().unwrap().height;
                let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(self);
                self.pending_outbound_payments
                        .send_payment_with_route(route, payment_hash, recipient_onion, payment_id,
@@ -3525,7 +3582,7 @@ where
        /// Similar to [`ChannelManager::send_payment_with_route`], but will automatically find a route based on
        /// `route_params` and retry failed payment paths based on `retry_strategy`.
        pub fn send_payment(&self, payment_hash: PaymentHash, recipient_onion: RecipientOnionFields, payment_id: PaymentId, route_params: RouteParameters, retry_strategy: Retry) -> Result<(), RetryableSendFailure> {
-               let best_block_height = self.best_block.read().unwrap().height();
+               let best_block_height = self.best_block.read().unwrap().height;
                let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(self);
                self.pending_outbound_payments
                        .send_payment(payment_hash, recipient_onion, payment_id, retry_strategy, route_params,
@@ -3536,7 +3593,7 @@ where
 
        #[cfg(test)]
        pub(super) fn test_send_payment_internal(&self, route: &Route, payment_hash: PaymentHash, recipient_onion: RecipientOnionFields, keysend_preimage: Option<PaymentPreimage>, payment_id: PaymentId, recv_value_msat: Option<u64>, onion_session_privs: Vec<[u8; 32]>) -> Result<(), PaymentSendFailure> {
-               let best_block_height = self.best_block.read().unwrap().height();
+               let best_block_height = self.best_block.read().unwrap().height;
                let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(self);
                self.pending_outbound_payments.test_send_payment_internal(route, payment_hash, recipient_onion,
                        keysend_preimage, payment_id, recv_value_msat, onion_session_privs, &self.node_signer,
@@ -3545,7 +3602,7 @@ where
 
        #[cfg(test)]
        pub(crate) fn test_add_new_pending_payment(&self, payment_hash: PaymentHash, recipient_onion: RecipientOnionFields, payment_id: PaymentId, route: &Route) -> Result<Vec<[u8; 32]>, PaymentSendFailure> {
-               let best_block_height = self.best_block.read().unwrap().height();
+               let best_block_height = self.best_block.read().unwrap().height;
                self.pending_outbound_payments.test_add_new_pending_payment(payment_hash, recipient_onion, payment_id, route, None, &self.entropy_source, best_block_height)
        }
 
@@ -3555,7 +3612,7 @@ where
        }
 
        pub(super) fn send_payment_for_bolt12_invoice(&self, invoice: &Bolt12Invoice, payment_id: PaymentId) -> Result<(), Bolt12PaymentError> {
-               let best_block_height = self.best_block.read().unwrap().height();
+               let best_block_height = self.best_block.read().unwrap().height;
                let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(self);
                self.pending_outbound_payments
                        .send_payment_for_bolt12_invoice(
@@ -3612,7 +3669,7 @@ where
        ///
        /// [`send_payment`]: Self::send_payment
        pub fn send_spontaneous_payment(&self, route: &Route, payment_preimage: Option<PaymentPreimage>, recipient_onion: RecipientOnionFields, payment_id: PaymentId) -> Result<PaymentHash, PaymentSendFailure> {
-               let best_block_height = self.best_block.read().unwrap().height();
+               let best_block_height = self.best_block.read().unwrap().height;
                let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(self);
                self.pending_outbound_payments.send_spontaneous_payment_with_route(
                        route, payment_preimage, recipient_onion, payment_id, &self.entropy_source,
@@ -3627,7 +3684,7 @@ where
        ///
        /// [`PaymentParameters::for_keysend`]: crate::routing::router::PaymentParameters::for_keysend
        pub fn send_spontaneous_payment_with_retry(&self, payment_preimage: Option<PaymentPreimage>, recipient_onion: RecipientOnionFields, payment_id: PaymentId, route_params: RouteParameters, retry_strategy: Retry) -> Result<PaymentHash, RetryableSendFailure> {
-               let best_block_height = self.best_block.read().unwrap().height();
+               let best_block_height = self.best_block.read().unwrap().height;
                let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(self);
                self.pending_outbound_payments.send_spontaneous_payment(payment_preimage, recipient_onion,
                        payment_id, retry_strategy, route_params, &self.router, self.list_usable_channels(),
@@ -3639,7 +3696,7 @@ where
        /// [`PaymentHash`] of probes based on a static secret and a random [`PaymentId`], which allows
        /// us to easily discern them from real payments.
        pub fn send_probe(&self, path: Path) -> Result<(PaymentHash, PaymentId), PaymentSendFailure> {
-               let best_block_height = self.best_block.read().unwrap().height();
+               let best_block_height = self.best_block.read().unwrap().height;
                let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(self);
                self.pending_outbound_payments.send_probe(path, self.probing_cookie_secret,
                        &self.entropy_source, &self.node_signer, best_block_height,
@@ -3917,7 +3974,7 @@ where
                        }));
                }
                {
-                       let height = self.best_block.read().unwrap().height();
+                       let height = self.best_block.read().unwrap().height;
                        // Transactions are evaluated as final by network mempools if their locktime is strictly
                        // lower than the next block height. However, the modules constituting our Lightning
                        // node might not have perfect sync about their blockchain views. Thus, if the wallet
@@ -4247,6 +4304,145 @@ where
                Ok(())
        }
 
+       fn process_pending_update_add_htlcs(&self) {
+               let mut decode_update_add_htlcs = new_hash_map();
+               mem::swap(&mut decode_update_add_htlcs, &mut self.decode_update_add_htlcs.lock().unwrap());
+
+               let get_failed_htlc_destination = |outgoing_scid_opt: Option<u64>, payment_hash: PaymentHash| {
+                       if let Some(outgoing_scid) = outgoing_scid_opt {
+                               match self.short_to_chan_info.read().unwrap().get(&outgoing_scid) {
+                                       Some((outgoing_counterparty_node_id, outgoing_channel_id)) =>
+                                               HTLCDestination::NextHopChannel {
+                                                       node_id: Some(*outgoing_counterparty_node_id),
+                                                       channel_id: *outgoing_channel_id,
+                                               },
+                                       None => HTLCDestination::UnknownNextHop {
+                                               requested_forward_scid: outgoing_scid,
+                                       },
+                               }
+                       } else {
+                               HTLCDestination::FailedPayment { payment_hash }
+                       }
+               };
+
+               'outer_loop: for (incoming_scid, update_add_htlcs) in decode_update_add_htlcs {
+                       let incoming_channel_details_opt = self.do_funded_channel_callback(incoming_scid, |chan: &mut Channel<SP>| {
+                               let counterparty_node_id = chan.context.get_counterparty_node_id();
+                               let channel_id = chan.context.channel_id();
+                               let funding_txo = chan.context.get_funding_txo().unwrap();
+                               let user_channel_id = chan.context.get_user_id();
+                               let accept_underpaying_htlcs = chan.context.config().accept_underpaying_htlcs;
+                               (counterparty_node_id, channel_id, funding_txo, user_channel_id, accept_underpaying_htlcs)
+                       });
+                       let (
+                               incoming_counterparty_node_id, incoming_channel_id, incoming_funding_txo,
+                               incoming_user_channel_id, incoming_accept_underpaying_htlcs
+                        ) = if let Some(incoming_channel_details) = incoming_channel_details_opt {
+                               incoming_channel_details
+                       } else {
+                               // The incoming channel no longer exists, HTLCs should be resolved onchain instead.
+                               continue;
+                       };
+
+                       let mut htlc_forwards = Vec::new();
+                       let mut htlc_fails = Vec::new();
+                       for update_add_htlc in &update_add_htlcs {
+                               let (next_hop, shared_secret, next_packet_details_opt) = match decode_incoming_update_add_htlc_onion(
+                                       &update_add_htlc, &self.node_signer, &self.logger, &self.secp_ctx
+                               ) {
+                                       Ok(decoded_onion) => decoded_onion,
+                                       Err(htlc_fail) => {
+                                               htlc_fails.push((htlc_fail, HTLCDestination::InvalidOnion));
+                                               continue;
+                                       },
+                               };
+
+                               let is_intro_node_blinded_forward = next_hop.is_intro_node_blinded_forward();
+                               let outgoing_scid_opt = next_packet_details_opt.as_ref().map(|d| d.outgoing_scid);
+
+                               // Process the HTLC on the incoming channel.
+                               match self.do_funded_channel_callback(incoming_scid, |chan: &mut Channel<SP>| {
+                                       let logger = WithChannelContext::from(&self.logger, &chan.context);
+                                       chan.can_accept_incoming_htlc(
+                                               update_add_htlc, &self.fee_estimator, &logger,
+                                       )
+                               }) {
+                                       Some(Ok(_)) => {},
+                                       Some(Err((err, code))) => {
+                                               let outgoing_chan_update_opt = if let Some(outgoing_scid) = outgoing_scid_opt.as_ref() {
+                                                       self.do_funded_channel_callback(*outgoing_scid, |chan: &mut Channel<SP>| {
+                                                               self.get_channel_update_for_onion(*outgoing_scid, chan).ok()
+                                                       }).flatten()
+                                               } else {
+                                                       None
+                                               };
+                                               let htlc_fail = self.htlc_failure_from_update_add_err(
+                                                       &update_add_htlc, &incoming_counterparty_node_id, err, code,
+                                                       outgoing_chan_update_opt, is_intro_node_blinded_forward, &shared_secret,
+                                               );
+                                               let htlc_destination = get_failed_htlc_destination(outgoing_scid_opt, update_add_htlc.payment_hash);
+                                               htlc_fails.push((htlc_fail, htlc_destination));
+                                               continue;
+                                       },
+                                       // The incoming channel no longer exists, HTLCs should be resolved onchain instead.
+                                       None => continue 'outer_loop,
+                               }
+
+                               // Now process the HTLC on the outgoing channel if it's a forward.
+                               if let Some(next_packet_details) = next_packet_details_opt.as_ref() {
+                                       if let Err((err, code, chan_update_opt)) = self.can_forward_htlc(
+                                               &update_add_htlc, next_packet_details
+                                       ) {
+                                               let htlc_fail = self.htlc_failure_from_update_add_err(
+                                                       &update_add_htlc, &incoming_counterparty_node_id, err, code,
+                                                       chan_update_opt, is_intro_node_blinded_forward, &shared_secret,
+                                               );
+                                               let htlc_destination = get_failed_htlc_destination(outgoing_scid_opt, update_add_htlc.payment_hash);
+                                               htlc_fails.push((htlc_fail, htlc_destination));
+                                               continue;
+                                       }
+                               }
+
+                               match self.construct_pending_htlc_status(
+                                       &update_add_htlc, &incoming_counterparty_node_id, shared_secret, next_hop,
+                                       incoming_accept_underpaying_htlcs, next_packet_details_opt.map(|d| d.next_packet_pubkey),
+                               ) {
+                                       PendingHTLCStatus::Forward(htlc_forward) => {
+                                               htlc_forwards.push((htlc_forward, update_add_htlc.htlc_id));
+                                       },
+                                       PendingHTLCStatus::Fail(htlc_fail) => {
+                                               let htlc_destination = get_failed_htlc_destination(outgoing_scid_opt, update_add_htlc.payment_hash);
+                                               htlc_fails.push((htlc_fail, htlc_destination));
+                                       },
+                               }
+                       }
+
+                       // Process all of the forwards and failures for the channel in which the HTLCs were
+                       // proposed to as a batch.
+                       let pending_forwards = (incoming_scid, incoming_funding_txo, incoming_channel_id,
+                               incoming_user_channel_id, htlc_forwards.drain(..).collect());
+                       self.forward_htlcs_without_forward_event(&mut [pending_forwards]);
+                       for (htlc_fail, htlc_destination) in htlc_fails.drain(..) {
+                               let failure = match htlc_fail {
+                                       HTLCFailureMsg::Relay(fail_htlc) => HTLCForwardInfo::FailHTLC {
+                                               htlc_id: fail_htlc.htlc_id,
+                                               err_packet: fail_htlc.reason,
+                                       },
+                                       HTLCFailureMsg::Malformed(fail_malformed_htlc) => HTLCForwardInfo::FailMalformedHTLC {
+                                               htlc_id: fail_malformed_htlc.htlc_id,
+                                               sha256_of_onion: fail_malformed_htlc.sha256_of_onion,
+                                               failure_code: fail_malformed_htlc.failure_code,
+                                       },
+                               };
+                               self.forward_htlcs.lock().unwrap().entry(incoming_scid).or_insert(vec![]).push(failure);
+                               self.pending_events.lock().unwrap().push_back((events::Event::HTLCHandlingFailed {
+                                       prev_channel_id: incoming_channel_id,
+                                       failed_next_destination: htlc_destination,
+                               }, None));
+                       }
+               }
+       }
+
        /// Processes HTLCs which are pending waiting on random forward delay.
        ///
        /// Should only really ever be called in response to a PendingHTLCsForwardable event.
@@ -4254,6 +4450,8 @@ where
        pub fn process_pending_htlc_forwards(&self) {
                let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(self);
 
+               self.process_pending_update_add_htlcs();
+
                let mut new_events = VecDeque::new();
                let mut failed_forwards = Vec::new();
                let mut phantom_receives: Vec<(u64, OutPoint, ChannelId, u128, Vec<(PendingHTLCInfo, u64)>)> = Vec::new();
@@ -4341,7 +4539,7 @@ where
                                                                                                };
                                                                                                match next_hop {
                                                                                                        onion_utils::Hop::Receive(hop_data) => {
-                                                                                                               let current_height: u32 = self.best_block.read().unwrap().height();
+                                                                                                               let current_height: u32 = self.best_block.read().unwrap().height;
                                                                                                                match create_recv_pending_htlc_info(hop_data,
                                                                                                                        incoming_shared_secret, payment_hash, outgoing_amt_msat,
                                                                                                                        outgoing_cltv_value, Some(phantom_shared_secret), false, None,
@@ -4494,7 +4692,10 @@ where
                                                                                (incoming_cltv_expiry, OnionPayload::Invoice { _legacy_hop_data },
                                                                                        Some(payment_data), phantom_shared_secret, onion_fields)
                                                                        },
-                                                                       PendingHTLCRouting::ReceiveKeysend { payment_data, payment_preimage, payment_metadata, incoming_cltv_expiry, custom_tlvs } => {
+                                                                       PendingHTLCRouting::ReceiveKeysend {
+                                                                               payment_data, payment_preimage, payment_metadata,
+                                                                               incoming_cltv_expiry, custom_tlvs, requires_blinded_error: _
+                                                                       } => {
                                                                                let onion_fields = RecipientOnionFields {
                                                                                        payment_secret: payment_data.as_ref().map(|data| data.payment_secret),
                                                                                        payment_metadata,
@@ -4538,7 +4739,7 @@ where
                                                                                debug_assert!(!committed_to_claimable);
                                                                                let mut htlc_msat_height_data = $htlc.value.to_be_bytes().to_vec();
                                                                                htlc_msat_height_data.extend_from_slice(
-                                                                                       &self.best_block.read().unwrap().height().to_be_bytes(),
+                                                                                       &self.best_block.read().unwrap().height.to_be_bytes(),
                                                                                );
                                                                                failed_forwards.push((HTLCSource::PreviousHopData(HTLCPreviousHopData {
                                                                                                short_channel_id: $htlc.prev_hop.short_channel_id,
@@ -4676,7 +4877,7 @@ where
                                                                                                        }
                                                                                                };
                                                                                                if let Some(min_final_cltv_expiry_delta) = min_final_cltv_expiry_delta {
-                                                                                                       let expected_min_expiry_height = (self.current_best_block().height() + min_final_cltv_expiry_delta as u32) as u64;
+                                                                                                       let expected_min_expiry_height = (self.current_best_block().height + min_final_cltv_expiry_delta as u32) as u64;
                                                                                                        if (cltv_expiry as u64) < expected_min_expiry_height {
                                                                                                                log_trace!(self.logger, "Failing new HTLC with payment_hash {} as its CLTV expiry was too soon (had {}, earliest expected {})",
                                                                                                                        &payment_hash, cltv_expiry, expected_min_expiry_height);
@@ -4730,7 +4931,7 @@ where
                        }
                }
 
-               let best_block_height = self.best_block.read().unwrap().height();
+               let best_block_height = self.best_block.read().unwrap().height;
                self.pending_outbound_payments.check_retry_payments(&self.router, || self.list_usable_channels(),
                        || self.compute_inflight_htlcs(), &self.entropy_source, &self.node_signer, best_block_height,
                        &self.pending_events, &self.logger, |args| self.send_payment_along_path(args));
@@ -4833,10 +5034,6 @@ where
 
                // If the feerate has decreased by less than half, don't bother
                if new_feerate <= chan.context.get_feerate_sat_per_1000_weight() && new_feerate * 2 > chan.context.get_feerate_sat_per_1000_weight() {
-                       if new_feerate != chan.context.get_feerate_sat_per_1000_weight() {
-                               log_trace!(logger, "Channel {} does not qualify for a feerate change from {} to {}.",
-                               chan_id, chan.context.get_feerate_sat_per_1000_weight(), new_feerate);
-                       }
                        return NotifyOption::SkipPersistNoEvents;
                }
                if !chan.context.is_live() {
@@ -5035,6 +5232,16 @@ where
                                                                process_unfunded_channel_tick(chan_id, &mut chan.context, &mut chan.unfunded_context,
                                                                        pending_msg_events, counterparty_node_id)
                                                        },
+                                                       #[cfg(dual_funding)]
+                                                       ChannelPhase::UnfundedInboundV2(chan) => {
+                                                               process_unfunded_channel_tick(chan_id, &mut chan.context, &mut chan.unfunded_context,
+                                                                       pending_msg_events, counterparty_node_id)
+                                                       },
+                                                       #[cfg(dual_funding)]
+                                                       ChannelPhase::UnfundedOutboundV2(chan) => {
+                                                               process_unfunded_channel_tick(chan_id, &mut chan.context, &mut chan.unfunded_context,
+                                                                       pending_msg_events, counterparty_node_id)
+                                                       },
                                                }
                                        });
 
@@ -5195,7 +5402,7 @@ where
                        FailureCode::RequiredNodeFeatureMissing => HTLCFailReason::from_failure_code(failure_code.into()),
                        FailureCode::IncorrectOrUnknownPaymentDetails => {
                                let mut htlc_msat_height_data = htlc.value.to_be_bytes().to_vec();
-                               htlc_msat_height_data.extend_from_slice(&self.best_block.read().unwrap().height().to_be_bytes());
+                               htlc_msat_height_data.extend_from_slice(&self.best_block.read().unwrap().height.to_be_bytes());
                                HTLCFailReason::reason(failure_code.into(), htlc_msat_height_data)
                        },
                        FailureCode::InvalidOnionPayload(data) => {
@@ -5289,9 +5496,14 @@ where
                }
        }
 
+       fn fail_htlc_backwards_internal(&self, source: &HTLCSource, payment_hash: &PaymentHash, onion_error: &HTLCFailReason, destination: HTLCDestination) {
+               let push_forward_event = self.fail_htlc_backwards_internal_without_forward_event(source, payment_hash, onion_error, destination);
+               if push_forward_event { self.push_pending_forwards_ev(); }
+       }
+
        /// Fails an HTLC backwards to the sender of it to us.
        /// Note that we do not assume that channels corresponding to failed HTLCs are still available.
-       fn fail_htlc_backwards_internal(&self, source: &HTLCSource, payment_hash: &PaymentHash, onion_error: &HTLCFailReason, destination: HTLCDestination) {
+       fn fail_htlc_backwards_internal_without_forward_event(&self, source: &HTLCSource, payment_hash: &PaymentHash, onion_error: &HTLCFailReason, destination: HTLCDestination) -> bool {
                // Ensure that no peer state channel storage lock is held when calling this function.
                // This ensures that future code doesn't introduce a lock-order requirement for
                // `forward_htlcs` to be locked after the `per_peer_state` peer locks, which calling
@@ -5309,12 +5521,12 @@ where
                // Note that we MUST NOT end up calling methods on self.chain_monitor here - we're called
                // from block_connected which may run during initialization prior to the chain_monitor
                // being fully configured. See the docs for `ChannelManagerReadArgs` for more.
+               let mut push_forward_event;
                match source {
                        HTLCSource::OutboundRoute { ref path, ref session_priv, ref payment_id, .. } => {
-                               if self.pending_outbound_payments.fail_htlc(source, payment_hash, onion_error, path,
+                               push_forward_event = self.pending_outbound_payments.fail_htlc(source, payment_hash, onion_error, path,
                                        session_priv, payment_id, self.probing_cookie_secret, &self.secp_ctx,
-                                       &self.pending_events, &self.logger)
-                               { self.push_pending_forwards_ev(); }
+                                       &self.pending_events, &self.logger);
                        },
                        HTLCSource::PreviousHopData(HTLCPreviousHopData {
                                ref short_channel_id, ref htlc_id, ref incoming_packet_shared_secret,
@@ -5348,11 +5560,9 @@ where
                                        }
                                };
 
-                               let mut push_forward_ev = false;
+                               push_forward_event = self.decode_update_add_htlcs.lock().unwrap().is_empty();
                                let mut forward_htlcs = self.forward_htlcs.lock().unwrap();
-                               if forward_htlcs.is_empty() {
-                                       push_forward_ev = true;
-                               }
+                               push_forward_event &= forward_htlcs.is_empty();
                                match forward_htlcs.entry(*short_channel_id) {
                                        hash_map::Entry::Occupied(mut entry) => {
                                                entry.get_mut().push(failure);
@@ -5362,7 +5572,6 @@ where
                                        }
                                }
                                mem::drop(forward_htlcs);
-                               if push_forward_ev { self.push_pending_forwards_ev(); }
                                let mut pending_events = self.pending_events.lock().unwrap();
                                pending_events.push_back((events::Event::HTLCHandlingFailed {
                                        prev_channel_id: *channel_id,
@@ -5370,6 +5579,7 @@ where
                                }, None));
                        },
                }
+               push_forward_event
        }
 
        /// Provides a payment preimage in response to [`Event::PaymentClaimable`], generating any
@@ -5526,7 +5736,7 @@ where
                if !valid_mpp {
                        for htlc in sources.drain(..) {
                                let mut htlc_msat_height_data = htlc.value.to_be_bytes().to_vec();
-                               htlc_msat_height_data.extend_from_slice(&self.best_block.read().unwrap().height().to_be_bytes());
+                               htlc_msat_height_data.extend_from_slice(&self.best_block.read().unwrap().height.to_be_bytes());
                                let source = HTLCSource::PreviousHopData(htlc.prev_hop);
                                let reason = HTLCFailReason::reason(0x4000 | 15, htlc_msat_height_data);
                                let receiver = HTLCDestination::FailedPayment { payment_hash };
@@ -5705,7 +5915,7 @@ where
        fn claim_funds_internal(&self, source: HTLCSource, payment_preimage: PaymentPreimage,
                forwarded_htlc_value_msat: Option<u64>, skimmed_fee_msat: Option<u64>, from_onchain: bool,
                startup_replay: bool, next_channel_counterparty_node_id: Option<PublicKey>,
-               next_channel_outpoint: OutPoint, next_channel_id: ChannelId,
+               next_channel_outpoint: OutPoint, next_channel_id: ChannelId, next_user_channel_id: Option<u128>,
        ) {
                match source {
                        HTLCSource::OutboundRoute { session_priv, payment_id, path, .. } => {
@@ -5724,11 +5934,10 @@ where
                        },
                        HTLCSource::PreviousHopData(hop_data) => {
                                let prev_channel_id = hop_data.channel_id;
+                               let prev_user_channel_id = hop_data.user_channel_id;
                                let completed_blocker = RAAMonitorUpdateBlockingAction::from_prev_hop_data(&hop_data);
                                #[cfg(debug_assertions)]
                                let claiming_chan_funding_outpoint = hop_data.outpoint;
-                               #[cfg(debug_assertions)]
-                               let claiming_channel_id = hop_data.channel_id;
                                let res = self.claim_funds_from_hop(hop_data, payment_preimage,
                                        |htlc_claim_value_msat, definitely_duplicate| {
                                                let chan_to_release =
@@ -5786,7 +5995,7 @@ where
                                                                                BackgroundEvent::MonitorUpdatesComplete {
                                                                                        channel_id, ..
                                                                                } =>
-                                                                                       *channel_id == claiming_channel_id,
+                                                                                       *channel_id == prev_channel_id,
                                                                        }
                                                                }), "{:?}", *background_events);
                                                        }
@@ -5810,12 +6019,14 @@ where
                                                                "skimmed_fee_msat must always be included in total_fee_earned_msat");
                                                        Some(MonitorUpdateCompletionAction::EmitEventAndFreeOtherChannel {
                                                                event: events::Event::PaymentForwarded {
-                                                                       total_fee_earned_msat,
-                                                                       claim_from_onchain_tx: from_onchain,
                                                                        prev_channel_id: Some(prev_channel_id),
                                                                        next_channel_id: Some(next_channel_id),
-                                                                       outbound_amount_forwarded_msat: forwarded_htlc_value_msat,
+                                                                       prev_user_channel_id,
+                                                                       next_user_channel_id,
+                                                                       total_fee_earned_msat,
                                                                        skimmed_fee_msat,
+                                                                       claim_from_onchain_tx: from_onchain,
+                                                                       outbound_amount_forwarded_msat: forwarded_htlc_value_msat,
                                                                },
                                                                downstream_counterparty_and_funding_outpoint: chan_to_release,
                                                        })
@@ -5887,24 +6098,31 @@ where
        fn handle_channel_resumption(&self, pending_msg_events: &mut Vec<MessageSendEvent>,
                channel: &mut Channel<SP>, raa: Option<msgs::RevokeAndACK>,
                commitment_update: Option<msgs::CommitmentUpdate>, order: RAACommitmentOrder,
-               pending_forwards: Vec<(PendingHTLCInfo, u64)>, funding_broadcastable: Option<Transaction>,
+               pending_forwards: Vec<(PendingHTLCInfo, u64)>, pending_update_adds: Vec<msgs::UpdateAddHTLC>,
+               funding_broadcastable: Option<Transaction>,
                channel_ready: Option<msgs::ChannelReady>, announcement_sigs: Option<msgs::AnnouncementSignatures>)
-       -> Option<(u64, OutPoint, ChannelId, u128, Vec<(PendingHTLCInfo, u64)>)> {
+       -> (Option<(u64, OutPoint, ChannelId, u128, Vec<(PendingHTLCInfo, u64)>)>, Option<(u64, Vec<msgs::UpdateAddHTLC>)>) {
                let logger = WithChannelContext::from(&self.logger, &channel.context);
-               log_trace!(logger, "Handling channel resumption for channel {} with {} RAA, {} commitment update, {} pending forwards, {}broadcasting funding, {} channel ready, {} announcement",
+               log_trace!(logger, "Handling channel resumption for channel {} with {} RAA, {} commitment update, {} pending forwards, {} pending update_add_htlcs, {}broadcasting funding, {} channel ready, {} announcement",
                        &channel.context.channel_id(),
                        if raa.is_some() { "an" } else { "no" },
-                       if commitment_update.is_some() { "a" } else { "no" }, pending_forwards.len(),
+                       if commitment_update.is_some() { "a" } else { "no" },
+                       pending_forwards.len(), pending_update_adds.len(),
                        if funding_broadcastable.is_some() { "" } else { "not " },
                        if channel_ready.is_some() { "sending" } else { "without" },
                        if announcement_sigs.is_some() { "sending" } else { "without" });
 
-               let mut htlc_forwards = None;
-
                let counterparty_node_id = channel.context.get_counterparty_node_id();
+               let short_channel_id = channel.context.get_short_channel_id().unwrap_or(channel.context.outbound_scid_alias());
+
+               let mut htlc_forwards = None;
                if !pending_forwards.is_empty() {
-                       htlc_forwards = Some((channel.context.get_short_channel_id().unwrap_or(channel.context.outbound_scid_alias()),
-                               channel.context.get_funding_txo().unwrap(), channel.context.channel_id(), channel.context.get_user_id(), pending_forwards));
+                       htlc_forwards = Some((short_channel_id, channel.context.get_funding_txo().unwrap(),
+                               channel.context.channel_id(), channel.context.get_user_id(), pending_forwards));
+               }
+               let mut decode_update_add_htlcs = None;
+               if !pending_update_adds.is_empty() {
+                       decode_update_add_htlcs = Some((short_channel_id, pending_update_adds));
                }
 
                if let Some(msg) = channel_ready {
@@ -5955,7 +6173,7 @@ where
                        emit_channel_ready_event!(pending_events, channel);
                }
 
-               htlc_forwards
+               (htlc_forwards, decode_update_add_htlcs)
        }
 
        fn channel_monitor_updated(&self, funding_txo: &OutPoint, channel_id: &ChannelId, highest_applied_update_id: u64, counterparty_node_id: Option<&PublicKey>) {
@@ -6070,73 +6288,82 @@ where
                // happening and return an error. N.B. that we create channel with an outbound SCID of zero so
                // that we can delay allocating the SCID until after we're sure that the checks below will
                // succeed.
-               let mut channel = match peer_state.inbound_channel_request_by_id.remove(temporary_channel_id) {
+               let res = match peer_state.inbound_channel_request_by_id.remove(temporary_channel_id) {
                        Some(unaccepted_channel) => {
-                               let best_block_height = self.best_block.read().unwrap().height();
+                               let best_block_height = self.best_block.read().unwrap().height;
                                InboundV1Channel::new(&self.fee_estimator, &self.entropy_source, &self.signer_provider,
                                        counterparty_node_id.clone(), &self.channel_type_features(), &peer_state.latest_features,
                                        &unaccepted_channel.open_channel_msg, user_channel_id, &self.default_configuration, best_block_height,
-                                       &self.logger, accept_0conf).map_err(|e| {
-                                               let err_str = e.to_string();
-                                               log_error!(logger, "{}", err_str);
-
-                                               APIError::ChannelUnavailable { err: err_str }
-                                       })
-                               }
+                                       &self.logger, accept_0conf).map_err(|err| MsgHandleErrInternal::from_chan_no_close(err, *temporary_channel_id))
+                       },
                        _ => {
                                let err_str = "No such channel awaiting to be accepted.".to_owned();
                                log_error!(logger, "{}", err_str);
 
-                               Err(APIError::APIMisuseError { err: err_str })
+                               return Err(APIError::APIMisuseError { err: err_str });
                        }
-               }?;
+               };
 
-               if accept_0conf {
-                       // This should have been correctly configured by the call to InboundV1Channel::new.
-                       debug_assert!(channel.context.minimum_depth().unwrap() == 0);
-               } else if channel.context.get_channel_type().requires_zero_conf() {
-                       let send_msg_err_event = events::MessageSendEvent::HandleError {
-                               node_id: channel.context.get_counterparty_node_id(),
-                               action: msgs::ErrorAction::SendErrorMessage{
-                                       msg: msgs::ErrorMessage { channel_id: temporary_channel_id.clone(), data: "No zero confirmation channels accepted".to_owned(), }
+               match res {
+                       Err(err) => {
+                               mem::drop(peer_state_lock);
+                               mem::drop(per_peer_state);
+                               match handle_error!(self, Result::<(), MsgHandleErrInternal>::Err(err), *counterparty_node_id) {
+                                       Ok(_) => unreachable!("`handle_error` only returns Err as we've passed in an Err"),
+                                       Err(e) => {
+                                               return Err(APIError::ChannelUnavailable { err: e.err });
+                                       },
                                }
-                       };
-                       peer_state.pending_msg_events.push(send_msg_err_event);
-                       let err_str = "Please use accept_inbound_channel_from_trusted_peer_0conf to accept channels with zero confirmations.".to_owned();
-                       log_error!(logger, "{}", err_str);
+                       }
+                       Ok(mut channel) => {
+                               if accept_0conf {
+                                       // This should have been correctly configured by the call to InboundV1Channel::new.
+                                       debug_assert!(channel.context.minimum_depth().unwrap() == 0);
+                               } else if channel.context.get_channel_type().requires_zero_conf() {
+                                       let send_msg_err_event = events::MessageSendEvent::HandleError {
+                                               node_id: channel.context.get_counterparty_node_id(),
+                                               action: msgs::ErrorAction::SendErrorMessage{
+                                                       msg: msgs::ErrorMessage { channel_id: temporary_channel_id.clone(), data: "No zero confirmation channels accepted".to_owned(), }
+                                               }
+                                       };
+                                       peer_state.pending_msg_events.push(send_msg_err_event);
+                                       let err_str = "Please use accept_inbound_channel_from_trusted_peer_0conf to accept channels with zero confirmations.".to_owned();
+                                       log_error!(logger, "{}", err_str);
 
-                       return Err(APIError::APIMisuseError { err: err_str });
-               } else {
-                       // If this peer already has some channels, a new channel won't increase our number of peers
-                       // with unfunded channels, so as long as we aren't over the maximum number of unfunded
-                       // channels per-peer we can accept channels from a peer with existing ones.
-                       if is_only_peer_channel && peers_without_funded_channels >= MAX_UNFUNDED_CHANNEL_PEERS {
-                               let send_msg_err_event = events::MessageSendEvent::HandleError {
-                                       node_id: channel.context.get_counterparty_node_id(),
-                                       action: msgs::ErrorAction::SendErrorMessage{
-                                               msg: msgs::ErrorMessage { channel_id: temporary_channel_id.clone(), data: "Have too many peers with unfunded channels, not accepting new ones".to_owned(), }
-                                       }
-                               };
-                               peer_state.pending_msg_events.push(send_msg_err_event);
-                               let err_str = "Too many peers with unfunded channels, refusing to accept new ones".to_owned();
-                               log_error!(logger, "{}", err_str);
+                                       return Err(APIError::APIMisuseError { err: err_str });
+                               } else {
+                                       // If this peer already has some channels, a new channel won't increase our number of peers
+                                       // with unfunded channels, so as long as we aren't over the maximum number of unfunded
+                                       // channels per-peer we can accept channels from a peer with existing ones.
+                                       if is_only_peer_channel && peers_without_funded_channels >= MAX_UNFUNDED_CHANNEL_PEERS {
+                                               let send_msg_err_event = events::MessageSendEvent::HandleError {
+                                                       node_id: channel.context.get_counterparty_node_id(),
+                                                       action: msgs::ErrorAction::SendErrorMessage{
+                                                               msg: msgs::ErrorMessage { channel_id: temporary_channel_id.clone(), data: "Have too many peers with unfunded channels, not accepting new ones".to_owned(), }
+                                                       }
+                                               };
+                                               peer_state.pending_msg_events.push(send_msg_err_event);
+                                               let err_str = "Too many peers with unfunded channels, refusing to accept new ones".to_owned();
+                                               log_error!(logger, "{}", err_str);
 
-                               return Err(APIError::APIMisuseError { err: err_str });
-                       }
-               }
+                                               return Err(APIError::APIMisuseError { err: err_str });
+                                       }
+                               }
 
-               // Now that we know we have a channel, assign an outbound SCID alias.
-               let outbound_scid_alias = self.create_and_insert_outbound_scid_alias();
-               channel.context.set_outbound_scid_alias(outbound_scid_alias);
+                               // Now that we know we have a channel, assign an outbound SCID alias.
+                               let outbound_scid_alias = self.create_and_insert_outbound_scid_alias();
+                               channel.context.set_outbound_scid_alias(outbound_scid_alias);
 
-               peer_state.pending_msg_events.push(events::MessageSendEvent::SendAcceptChannel {
-                       node_id: channel.context.get_counterparty_node_id(),
-                       msg: channel.accept_inbound_channel(),
-               });
+                               peer_state.pending_msg_events.push(events::MessageSendEvent::SendAcceptChannel {
+                                       node_id: channel.context.get_counterparty_node_id(),
+                                       msg: channel.accept_inbound_channel(),
+                               });
 
-               peer_state.channel_by_id.insert(temporary_channel_id.clone(), ChannelPhase::UnfundedInboundV1(channel));
+                               peer_state.channel_by_id.insert(temporary_channel_id.clone(), ChannelPhase::UnfundedInboundV1(channel));
 
-               Ok(())
+                               Ok(())
+                       },
+               }
        }
 
        /// Gets the number of peers which match the given filter and do not have any funded, outbound,
@@ -6147,7 +6374,7 @@ where
        fn peers_without_funded_channels<Filter>(&self, maybe_count_peer: Filter) -> usize
        where Filter: Fn(&PeerState<SP>) -> bool {
                let mut peers_without_funded_channels = 0;
-               let best_block_height = self.best_block.read().unwrap().height();
+               let best_block_height = self.best_block.read().unwrap().height;
                {
                        let peer_state_lock = self.per_peer_state.read().unwrap();
                        for (_, peer_mtx) in peer_state_lock.iter() {
@@ -6182,9 +6409,25 @@ where
                                                num_unfunded_channels += 1;
                                        }
                                },
+                               // TODO(dual_funding): Combine this match arm with above once #[cfg(dual_funding)] is removed.
+                               #[cfg(dual_funding)]
+                               ChannelPhase::UnfundedInboundV2(chan) => {
+                                       // Only inbound V2 channels that are not 0conf and that we do not contribute to will be
+                                       // included in the unfunded count.
+                                       if chan.context.minimum_depth().unwrap_or(1) != 0 &&
+                                               chan.dual_funding_context.our_funding_satoshis == 0 {
+                                               num_unfunded_channels += 1;
+                                       }
+                               },
                                ChannelPhase::UnfundedOutboundV1(_) => {
                                        // Outbound channels don't contribute to the unfunded count in the DoS context.
                                        continue;
+                               },
+                               // TODO(dual_funding): Combine this match arm with above once #[cfg(dual_funding)] is removed.
+                               #[cfg(dual_funding)]
+                               ChannelPhase::UnfundedOutboundV2(_) => {
+                                       // Outbound channels don't contribute to the unfunded count in the DoS context.
+                                       continue;
                                }
                        }
                }
@@ -6233,7 +6476,7 @@ where
                                msg.common_fields.temporary_channel_id.clone()));
                }
 
-               let best_block_height = self.best_block.read().unwrap().height();
+               let best_block_height = self.best_block.read().unwrap().height;
                if Self::unfunded_channel_count(peer_state, best_block_height) >= MAX_UNFUNDED_CHANS_PER_PEER {
                        return Err(MsgHandleErrInternal::send_err_msg_no_close(
                                format!("Refusing more than {} unfunded channels.", MAX_UNFUNDED_CHANS_PER_PEER),
@@ -6251,7 +6494,7 @@ where
                // If we're doing manual acceptance checks on the channel, then defer creation until we're sure we want to accept.
                if self.default_configuration.manually_accept_inbound_channels {
                        let channel_type = channel::channel_type_from_open_channel(
-                                       &msg, &peer_state.latest_features, &self.channel_type_features()
+                                       &msg.common_fields, &peer_state.latest_features, &self.channel_type_features()
                                ).map_err(|e|
                                        MsgHandleErrInternal::from_chan_no_close(e, msg.common_fields.temporary_channel_id)
                                )?;
@@ -6607,6 +6850,14 @@ where
                                                let mut chan = remove_channel_phase!(self, chan_phase_entry);
                                                finish_shutdown = Some(chan.context_mut().force_shutdown(false, ClosureReason::CounterpartyCoopClosedUnfundedChannel));
                                        },
+                                       // TODO(dual_funding): Combine this match arm with above.
+                                       #[cfg(dual_funding)]
+                                       ChannelPhase::UnfundedInboundV2(_) | ChannelPhase::UnfundedOutboundV2(_) => {
+                                               let context = phase.context_mut();
+                                               log_error!(self.logger, "Immediately closing unfunded channel {} as peer asked to cooperatively shut it down (which is unnecessary)", &msg.channel_id);
+                                               let mut chan = remove_channel_phase!(self, chan_phase_entry);
+                                               finish_shutdown = Some(chan.context_mut().force_shutdown(false, ClosureReason::CounterpartyCoopClosedUnfundedChannel));
+                                       },
                                }
                        } else {
                                return Err(MsgHandleErrInternal::send_err_msg_no_close(format!("Got a message for a channel from the wrong node! No such channel for the passed counterparty_node_id {}", counterparty_node_id), msg.channel_id))
@@ -6707,7 +6958,7 @@ where
                match peer_state.channel_by_id.entry(msg.channel_id) {
                        hash_map::Entry::Occupied(mut chan_phase_entry) => {
                                if let ChannelPhase::Funded(chan) = chan_phase_entry.get_mut() {
-                                       let pending_forward_info = match decoded_hop_res {
+                                       let mut pending_forward_info = match decoded_hop_res {
                                                Ok((next_hop, shared_secret, next_packet_pk_opt)) =>
                                                        self.construct_pending_htlc_status(
                                                                msg, counterparty_node_id, shared_secret, next_hop,
@@ -6715,44 +6966,45 @@ where
                                                        ),
                                                Err(e) => PendingHTLCStatus::Fail(e)
                                        };
-                                       let create_pending_htlc_status = |chan: &Channel<SP>, pending_forward_info: PendingHTLCStatus, error_code: u16| {
+                                       let logger = WithChannelContext::from(&self.logger, &chan.context);
+                                       // If the update_add is completely bogus, the call will Err and we will close,
+                                       // but if we've sent a shutdown and they haven't acknowledged it yet, we just
+                                       // want to reject the new HTLC and fail it backwards instead of forwarding.
+                                       if let Err((_, error_code)) = chan.can_accept_incoming_htlc(&msg, &self.fee_estimator, &logger) {
                                                if msg.blinding_point.is_some() {
-                                                       return PendingHTLCStatus::Fail(HTLCFailureMsg::Malformed(
-                                                                       msgs::UpdateFailMalformedHTLC {
-                                                                               channel_id: msg.channel_id,
-                                                                               htlc_id: msg.htlc_id,
-                                                                               sha256_of_onion: [0; 32],
-                                                                               failure_code: INVALID_ONION_BLINDING,
-                                                                       }
-                                                       ))
-                                               }
-                                               // If the update_add is completely bogus, the call will Err and we will close,
-                                               // but if we've sent a shutdown and they haven't acknowledged it yet, we just
-                                               // want to reject the new HTLC and fail it backwards instead of forwarding.
-                                               match pending_forward_info {
-                                                       PendingHTLCStatus::Forward(PendingHTLCInfo {
-                                                               ref incoming_shared_secret, ref routing, ..
-                                                       }) => {
-                                                               let reason = if routing.blinded_failure().is_some() {
-                                                                       HTLCFailReason::reason(INVALID_ONION_BLINDING, vec![0; 32])
-                                                               } else if (error_code & 0x1000) != 0 {
-                                                                       let (real_code, error_data) = self.get_htlc_inbound_temp_fail_err_and_data(error_code, chan);
-                                                                       HTLCFailReason::reason(real_code, error_data)
-                                                               } else {
-                                                                       HTLCFailReason::from_failure_code(error_code)
-                                                               }.get_encrypted_failure_packet(incoming_shared_secret, &None);
-                                                               let msg = msgs::UpdateFailHTLC {
+                                                       pending_forward_info = PendingHTLCStatus::Fail(HTLCFailureMsg::Malformed(
+                                                               msgs::UpdateFailMalformedHTLC {
                                                                        channel_id: msg.channel_id,
                                                                        htlc_id: msg.htlc_id,
-                                                                       reason
-                                                               };
-                                                               PendingHTLCStatus::Fail(HTLCFailureMsg::Relay(msg))
-                                                       },
-                                                       _ => pending_forward_info
+                                                                       sha256_of_onion: [0; 32],
+                                                                       failure_code: INVALID_ONION_BLINDING,
+                                                               }
+                                                       ))
+                                               } else {
+                                                       match pending_forward_info {
+                                                               PendingHTLCStatus::Forward(PendingHTLCInfo {
+                                                                       ref incoming_shared_secret, ref routing, ..
+                                                               }) => {
+                                                                       let reason = if routing.blinded_failure().is_some() {
+                                                                               HTLCFailReason::reason(INVALID_ONION_BLINDING, vec![0; 32])
+                                                                       } else if (error_code & 0x1000) != 0 {
+                                                                               let (real_code, error_data) = self.get_htlc_inbound_temp_fail_err_and_data(error_code, chan);
+                                                                               HTLCFailReason::reason(real_code, error_data)
+                                                                       } else {
+                                                                               HTLCFailReason::from_failure_code(error_code)
+                                                                       }.get_encrypted_failure_packet(incoming_shared_secret, &None);
+                                                                       let msg = msgs::UpdateFailHTLC {
+                                                                               channel_id: msg.channel_id,
+                                                                               htlc_id: msg.htlc_id,
+                                                                               reason
+                                                                       };
+                                                                       pending_forward_info = PendingHTLCStatus::Fail(HTLCFailureMsg::Relay(msg));
+                                                               },
+                                                               _ => {},
+                                                       }
                                                }
-                                       };
-                                       let logger = WithChannelContext::from(&self.logger, &chan.context);
-                                       try_chan_phase_entry!(self, chan.update_add_htlc(&msg, pending_forward_info, create_pending_htlc_status, &self.fee_estimator, &&logger), chan_phase_entry);
+                                       }
+                                       try_chan_phase_entry!(self, chan.update_add_htlc(&msg, pending_forward_info), chan_phase_entry);
                                } else {
                                        return try_chan_phase_entry!(self, Err(ChannelError::Close(
                                                "Got an update_add_htlc message for an unfunded channel!".into())), chan_phase_entry);
@@ -6765,6 +7017,7 @@ where
 
        fn internal_update_fulfill_htlc(&self, counterparty_node_id: &PublicKey, msg: &msgs::UpdateFulfillHTLC) -> Result<(), MsgHandleErrInternal> {
                let funding_txo;
+               let next_user_channel_id;
                let (htlc_source, forwarded_htlc_value, skimmed_fee_msat) = {
                        let per_peer_state = self.per_peer_state.read().unwrap();
                        let peer_state_mutex = per_peer_state.get(counterparty_node_id)
@@ -6794,6 +7047,7 @@ where
                                                // outbound HTLC is claimed. This is guaranteed to all complete before we
                                                // process the RAA as messages are processed from single peers serially.
                                                funding_txo = chan.context.get_funding_txo().expect("We won't accept a fulfill until funded");
+                                               next_user_channel_id = chan.context.get_user_id();
                                                res
                                        } else {
                                                return try_chan_phase_entry!(self, Err(ChannelError::Close(
@@ -6805,7 +7059,7 @@ where
                };
                self.claim_funds_internal(htlc_source, msg.payment_preimage.clone(),
                        Some(forwarded_htlc_value), skimmed_fee_msat, false, false, Some(*counterparty_node_id),
-                       funding_txo, msg.channel_id
+                       funding_txo, msg.channel_id, Some(next_user_channel_id),
                );
 
                Ok(())
@@ -6894,10 +7148,28 @@ where
                }
        }
 
+       fn push_decode_update_add_htlcs(&self, mut update_add_htlcs: (u64, Vec<msgs::UpdateAddHTLC>)) {
+               let mut push_forward_event = self.forward_htlcs.lock().unwrap().is_empty();
+               let mut decode_update_add_htlcs = self.decode_update_add_htlcs.lock().unwrap();
+               push_forward_event &= decode_update_add_htlcs.is_empty();
+               let scid = update_add_htlcs.0;
+               match decode_update_add_htlcs.entry(scid) {
+                       hash_map::Entry::Occupied(mut e) => { e.get_mut().append(&mut update_add_htlcs.1); },
+                       hash_map::Entry::Vacant(e) => { e.insert(update_add_htlcs.1); },
+               }
+               if push_forward_event { self.push_pending_forwards_ev(); }
+       }
+
        #[inline]
        fn forward_htlcs(&self, per_source_pending_forwards: &mut [(u64, OutPoint, ChannelId, u128, Vec<(PendingHTLCInfo, u64)>)]) {
+               let push_forward_event = self.forward_htlcs_without_forward_event(per_source_pending_forwards);
+               if push_forward_event { self.push_pending_forwards_ev() }
+       }
+
+       #[inline]
+       fn forward_htlcs_without_forward_event(&self, per_source_pending_forwards: &mut [(u64, OutPoint, ChannelId, u128, Vec<(PendingHTLCInfo, u64)>)]) -> bool {
+               let mut push_forward_event = false;
                for &mut (prev_short_channel_id, prev_funding_outpoint, prev_channel_id, prev_user_channel_id, ref mut pending_forwards) in per_source_pending_forwards {
-                       let mut push_forward_event = false;
                        let mut new_intercept_events = VecDeque::new();
                        let mut failed_intercept_forwards = Vec::new();
                        if !pending_forwards.is_empty() {
@@ -6910,6 +7182,7 @@ where
                                        // Pull this now to avoid introducing a lock order with `forward_htlcs`.
                                        let is_our_scid = self.short_to_chan_info.read().unwrap().contains_key(&scid);
 
+                                       let decode_update_add_htlcs_empty = self.decode_update_add_htlcs.lock().unwrap().is_empty();
                                        let mut forward_htlcs = self.forward_htlcs.lock().unwrap();
                                        let forward_htlcs_empty = forward_htlcs.is_empty();
                                        match forward_htlcs.entry(scid) {
@@ -6958,9 +7231,7 @@ where
                                                        } else {
                                                                // We don't want to generate a PendingHTLCsForwardable event if only intercepted
                                                                // payments are being processed.
-                                                               if forward_htlcs_empty {
-                                                                       push_forward_event = true;
-                                                               }
+                                                               push_forward_event |= forward_htlcs_empty && decode_update_add_htlcs_empty;
                                                                entry.insert(vec!(HTLCForwardInfo::AddHTLC(PendingAddHTLCInfo {
                                                                        prev_short_channel_id, prev_funding_outpoint, prev_channel_id, prev_htlc_id, prev_user_channel_id, forward_info })));
                                                        }
@@ -6970,15 +7241,15 @@ where
                        }
 
                        for (htlc_source, payment_hash, failure_reason, destination) in failed_intercept_forwards.drain(..) {
-                               self.fail_htlc_backwards_internal(&htlc_source, &payment_hash, &failure_reason, destination);
+                               push_forward_event |= self.fail_htlc_backwards_internal_without_forward_event(&htlc_source, &payment_hash, &failure_reason, destination);
                        }
 
                        if !new_intercept_events.is_empty() {
                                let mut events = self.pending_events.lock().unwrap();
                                events.append(&mut new_intercept_events);
                        }
-                       if push_forward_event { self.push_pending_forwards_ev() }
                }
+               push_forward_event
        }
 
        fn push_pending_forwards_ev(&self) {
@@ -7118,7 +7389,7 @@ where
 
                                        peer_state.pending_msg_events.push(events::MessageSendEvent::BroadcastChannelAnnouncement {
                                                msg: try_chan_phase_entry!(self, chan.announcement_signatures(
-                                                       &self.node_signer, self.chain_hash, self.best_block.read().unwrap().height(),
+                                                       &self.node_signer, self.chain_hash, self.best_block.read().unwrap().height,
                                                        msg, &self.default_configuration
                                                ), chan_phase_entry),
                                                // Note that announcement_signatures fails if the channel cannot be announced,
@@ -7188,7 +7459,6 @@ where
        }
 
        fn internal_channel_reestablish(&self, counterparty_node_id: &PublicKey, msg: &msgs::ChannelReestablish) -> Result<NotifyOption, MsgHandleErrInternal> {
-               let htlc_forwards;
                let need_lnd_workaround = {
                        let per_peer_state = self.per_peer_state.read().unwrap();
 
@@ -7231,9 +7501,11 @@ where
                                                        }
                                                }
                                                let need_lnd_workaround = chan.context.workaround_lnd_bug_4006.take();
-                                               htlc_forwards = self.handle_channel_resumption(
+                                               let (htlc_forwards, decode_update_add_htlcs) = self.handle_channel_resumption(
                                                        &mut peer_state.pending_msg_events, chan, responses.raa, responses.commitment_update, responses.order,
-                                                       Vec::new(), None, responses.channel_ready, responses.announcement_sigs);
+                                                       Vec::new(), Vec::new(), None, responses.channel_ready, responses.announcement_sigs);
+                                               debug_assert!(htlc_forwards.is_none());
+                                               debug_assert!(decode_update_add_htlcs.is_none());
                                                if let Some(upd) = channel_update {
                                                        peer_state.pending_msg_events.push(upd);
                                                }
@@ -7279,16 +7551,10 @@ where
                        }
                };
 
-               let mut persist = NotifyOption::SkipPersistHandleEvents;
-               if let Some(forwards) = htlc_forwards {
-                       self.forward_htlcs(&mut [forwards][..]);
-                       persist = NotifyOption::DoPersist;
-               }
-
                if let Some(channel_ready_msg) = need_lnd_workaround {
                        self.internal_channel_ready(counterparty_node_id, &channel_ready_msg)?;
                }
-               Ok(persist)
+               Ok(NotifyOption::SkipPersistHandleEvents)
        }
 
        /// Process pending events from the [`chain::Watch`], returning whether any events were processed.
@@ -7307,7 +7573,7 @@ where
                                                        log_trace!(logger, "Claiming HTLC with preimage {} from our monitor", preimage);
                                                        self.claim_funds_internal(htlc_update.source, preimage,
                                                                htlc_update.htlc_value_satoshis.map(|v| v * 1000), None, true,
-                                                               false, counterparty_node_id, funding_outpoint, channel_id);
+                                                               false, counterparty_node_id, funding_outpoint, channel_id, None);
                                                } else {
                                                        log_trace!(logger, "Failing HTLC with hash {} from our monitor", &htlc_update.payment_hash);
                                                        let receiver = HTLCDestination::NextHopChannel { node_id: counterparty_node_id, channel_id };
@@ -7315,7 +7581,7 @@ where
                                                        self.fail_htlc_backwards_internal(&htlc_update.source, &htlc_update.payment_hash, &reason, receiver);
                                                }
                                        },
-                                       MonitorEvent::HolderForceClosed(_funding_outpoint) => {
+                                       MonitorEvent::HolderForceClosed(_) | MonitorEvent::HolderForceClosedWithInfo { .. } => {
                                                let counterparty_node_id_opt = match counterparty_node_id {
                                                        Some(cp_id) => Some(cp_id),
                                                        None => {
@@ -7333,7 +7599,12 @@ where
                                                                let pending_msg_events = &mut peer_state.pending_msg_events;
                                                                if let hash_map::Entry::Occupied(chan_phase_entry) = peer_state.channel_by_id.entry(channel_id) {
                                                                        if let ChannelPhase::Funded(mut chan) = remove_channel_phase!(self, chan_phase_entry) {
-                                                                               failed_channels.push(chan.context.force_shutdown(false, ClosureReason::HolderForceClosed));
+                                                                               let reason = if let MonitorEvent::HolderForceClosedWithInfo { reason, .. } = monitor_event {
+                                                                                       reason
+                                                                               } else {
+                                                                                       ClosureReason::HolderForceClosed
+                                                                               };
+                                                                               failed_channels.push(chan.context.force_shutdown(false, reason.clone()));
                                                                                if let Ok(update) = self.get_channel_update_for_broadcast(&chan) {
                                                                                        pending_msg_events.push(events::MessageSendEvent::BroadcastChannelUpdate {
                                                                                                msg: update
@@ -7342,7 +7613,7 @@ where
                                                                                pending_msg_events.push(events::MessageSendEvent::HandleError {
                                                                                        node_id: chan.context.get_counterparty_node_id(),
                                                                                        action: msgs::ErrorAction::DisconnectPeer {
-                                                                                               msg: Some(msgs::ErrorMessage { channel_id: chan.context.channel_id(), data: "Channel force-closed".to_owned() })
+                                                                                               msg: Some(msgs::ErrorMessage { channel_id: chan.context.channel_id(), data: reason.to_string() })
                                                                                        },
                                                                                });
                                                                        }
@@ -7581,7 +7852,9 @@ where
                        self.finish_close_channel(failure);
                }
        }
+}
 
+macro_rules! create_offer_builder { ($self: ident, $builder: ty) => {
        /// Creates an [`OfferBuilder`] such that the [`Offer`] it builds is recognized by the
        /// [`ChannelManager`] when handling [`InvoiceRequest`] messages for the offer. The offer will
        /// not have an expiration unless otherwise set on the builder.
@@ -7610,23 +7883,25 @@ where
        /// [`Offer`]: crate::offers::offer::Offer
        /// [`InvoiceRequest`]: crate::offers::invoice_request::InvoiceRequest
        pub fn create_offer_builder(
-               &self, description: String
-       ) -> Result<OfferBuilder<DerivedMetadata, secp256k1::All>, Bolt12SemanticError> {
-               let node_id = self.get_our_node_id();
-               let expanded_key = &self.inbound_payment_key;
-               let entropy = &*self.entropy_source;
-               let secp_ctx = &self.secp_ctx;
-
-               let path = self.create_blinded_path().map_err(|_| Bolt12SemanticError::MissingPaths)?;
+               &$self, description: String
+       ) -> Result<$builder, Bolt12SemanticError> {
+               let node_id = $self.get_our_node_id();
+               let expanded_key = &$self.inbound_payment_key;
+               let entropy = &*$self.entropy_source;
+               let secp_ctx = &$self.secp_ctx;
+
+               let path = $self.create_blinded_path().map_err(|_| Bolt12SemanticError::MissingPaths)?;
                let builder = OfferBuilder::deriving_signing_pubkey(
                        description, node_id, expanded_key, entropy, secp_ctx
                )
-                       .chain_hash(self.chain_hash)
+                       .chain_hash($self.chain_hash)
                        .path(path);
 
-               Ok(builder)
+               Ok(builder.into())
        }
+} }
 
+macro_rules! create_refund_builder { ($self: ident, $builder: ty) => {
        /// Creates a [`RefundBuilder`] such that the [`Refund`] it builds is recognized by the
        /// [`ChannelManager`] when handling [`Bolt12Invoice`] messages for the refund.
        ///
@@ -7676,31 +7951,55 @@ where
        /// [`Bolt12Invoice::payment_paths`]: crate::offers::invoice::Bolt12Invoice::payment_paths
        /// [Avoiding Duplicate Payments]: #avoiding-duplicate-payments
        pub fn create_refund_builder(
-               &self, description: String, amount_msats: u64, absolute_expiry: Duration,
+               &$self, description: String, amount_msats: u64, absolute_expiry: Duration,
                payment_id: PaymentId, retry_strategy: Retry, max_total_routing_fee_msat: Option<u64>
-       ) -> Result<RefundBuilder<secp256k1::All>, Bolt12SemanticError> {
-               let node_id = self.get_our_node_id();
-               let expanded_key = &self.inbound_payment_key;
-               let entropy = &*self.entropy_source;
-               let secp_ctx = &self.secp_ctx;
+       ) -> Result<$builder, Bolt12SemanticError> {
+               let node_id = $self.get_our_node_id();
+               let expanded_key = &$self.inbound_payment_key;
+               let entropy = &*$self.entropy_source;
+               let secp_ctx = &$self.secp_ctx;
 
-               let path = self.create_blinded_path().map_err(|_| Bolt12SemanticError::MissingPaths)?;
+               let path = $self.create_blinded_path().map_err(|_| Bolt12SemanticError::MissingPaths)?;
                let builder = RefundBuilder::deriving_payer_id(
                        description, node_id, expanded_key, entropy, secp_ctx, amount_msats, payment_id
                )?
-                       .chain_hash(self.chain_hash)
+                       .chain_hash($self.chain_hash)
                        .absolute_expiry(absolute_expiry)
                        .path(path);
 
+               let _persistence_guard = PersistenceNotifierGuard::notify_on_drop($self);
+
                let expiration = StaleExpiration::AbsoluteTimeout(absolute_expiry);
-               self.pending_outbound_payments
+               $self.pending_outbound_payments
                        .add_new_awaiting_invoice(
                                payment_id, expiration, retry_strategy, max_total_routing_fee_msat,
                        )
                        .map_err(|_| Bolt12SemanticError::DuplicatePaymentId)?;
 
-               Ok(builder)
+               Ok(builder.into())
        }
+} }
+
+impl<M: Deref, T: Deref, ES: Deref, NS: Deref, SP: Deref, F: Deref, R: Deref, L: Deref> ChannelManager<M, T, ES, NS, SP, F, R, L>
+where
+       M::Target: chain::Watch<<SP::Target as SignerProvider>::EcdsaSigner>,
+       T::Target: BroadcasterInterface,
+       ES::Target: EntropySource,
+       NS::Target: NodeSigner,
+       SP::Target: SignerProvider,
+       F::Target: FeeEstimator,
+       R::Target: Router,
+       L::Target: Logger,
+{
+       #[cfg(not(c_bindings))]
+       create_offer_builder!(self, OfferBuilder<DerivedMetadata, secp256k1::All>);
+       #[cfg(not(c_bindings))]
+       create_refund_builder!(self, RefundBuilder<secp256k1::All>);
+
+       #[cfg(c_bindings)]
+       create_offer_builder!(self, OfferWithDerivedMetadataBuilder);
+       #[cfg(c_bindings)]
+       create_refund_builder!(self, RefundMaybeWithDerivedMetadataBuilder);
 
        /// Pays for an [`Offer`] using the given parameters by creating an [`InvoiceRequest`] and
        /// enqueuing it to be sent via an onion message. [`ChannelManager`] will pay the actual
@@ -7745,6 +8044,7 @@ where
        /// Errors if:
        /// - a duplicate `payment_id` is provided given the caveats in the aforementioned link,
        /// - the provided parameters are invalid for the offer,
+       /// - the offer is for an unsupported chain, or
        /// - the parameterized [`Router`] is unable to create a blinded reply path for the invoice
        ///   request.
        ///
@@ -7764,9 +8064,11 @@ where
                let entropy = &*self.entropy_source;
                let secp_ctx = &self.secp_ctx;
 
-               let builder = offer
+               let builder: InvoiceRequestBuilder<DerivedPayerId, secp256k1::All> = offer
                        .request_invoice_deriving_payer_id(expanded_key, entropy, secp_ctx, payment_id)?
-                       .chain_hash(self.chain_hash)?;
+                       .into();
+               let builder = builder.chain_hash(self.chain_hash)?;
+
                let builder = match quantity {
                        None => builder,
                        Some(quantity) => builder.quantity(quantity)?,
@@ -7782,6 +8084,8 @@ where
                let invoice_request = builder.build_and_sign()?;
                let reply_path = self.create_blinded_path().map_err(|_| Bolt12SemanticError::MissingPaths)?;
 
+               let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(self);
+
                let expiration = StaleExpiration::TimerTicks(1);
                self.pending_outbound_payments
                        .add_new_awaiting_invoice(
@@ -7831,8 +8135,10 @@ where
        ///
        /// # Errors
        ///
-       /// Errors if the parameterized [`Router`] is unable to create a blinded payment path or reply
-       /// path for the invoice.
+       /// Errors if:
+       /// - the refund is for an unsupported chain, or
+       /// - the parameterized [`Router`] is unable to create a blinded payment path or reply path for
+       ///   the invoice.
        ///
        /// [`Bolt12Invoice`]: crate::offers::invoice::Bolt12Invoice
        pub fn request_refund_payment(&self, refund: &Refund) -> Result<(), Bolt12SemanticError> {
@@ -7843,6 +8149,12 @@ where
                let amount_msats = refund.amount_msats();
                let relative_expiry = DEFAULT_RELATIVE_EXPIRY.as_secs() as u32;
 
+               if refund.chain() != self.chain_hash {
+                       return Err(Bolt12SemanticError::UnsupportedChain);
+               }
+
+               let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(self);
+
                match self.create_inbound_payment(Some(amount_msats), relative_expiry, None) {
                        Ok((payment_hash, payment_secret)) => {
                                let payment_paths = self.create_blinded_payment_paths(amount_msats, payment_secret)
@@ -7860,6 +8172,7 @@ where
                                let builder = refund.respond_using_derived_keys_no_std(
                                        payment_paths, payment_hash, created_at, expanded_key, entropy
                                )?;
+                               let builder: InvoiceBuilder<DerivedSigningPubkey> = builder.into();
                                let invoice = builder.allow_mpp().build_and_sign(secp_ctx)?;
                                let reply_path = self.create_blinded_path()
                                        .map_err(|_| Bolt12SemanticError::MissingPaths)?;
@@ -8016,7 +8329,7 @@ where
 
                let first_hops = self.list_usable_channels();
                let payee_node_id = self.get_our_node_id();
-               let max_cltv_expiry = self.best_block.read().unwrap().height() + CLTV_FAR_FAR_AWAY
+               let max_cltv_expiry = self.best_block.read().unwrap().height + CLTV_FAR_FAR_AWAY
                        + LATENCY_GRACE_PERIOD_BLOCKS;
                let payee_tlvs = ReceiveTlvs {
                        payment_secret,
@@ -8035,7 +8348,7 @@ where
        ///
        /// [phantom node payments]: crate::sign::PhantomKeysManager
        pub fn get_phantom_scid(&self) -> u64 {
-               let best_block_height = self.best_block.read().unwrap().height();
+               let best_block_height = self.best_block.read().unwrap().height;
                let short_to_chan_info = self.short_to_chan_info.read().unwrap();
                loop {
                        let scid_candidate = fake_scid::Namespace::Phantom.get_fake_scid(best_block_height, &self.chain_hash, &self.fake_scid_rand_bytes, &self.entropy_source);
@@ -8065,7 +8378,7 @@ where
        /// Note that this method is not guaranteed to return unique values, you may need to call it a few
        /// times to get a unique scid.
        pub fn get_intercept_scid(&self) -> u64 {
-               let best_block_height = self.best_block.read().unwrap().height();
+               let best_block_height = self.best_block.read().unwrap().height;
                let short_to_chan_info = self.short_to_chan_info.read().unwrap();
                loop {
                        let scid_candidate = fake_scid::Namespace::Intercept.get_fake_scid(best_block_height, &self.chain_hash, &self.fake_scid_rand_bytes, &self.entropy_source);
@@ -8313,9 +8626,9 @@ where
        fn filtered_block_connected(&self, header: &Header, txdata: &TransactionData, height: u32) {
                {
                        let best_block = self.best_block.read().unwrap();
-                       assert_eq!(best_block.block_hash(), header.prev_blockhash,
+                       assert_eq!(best_block.block_hash, header.prev_blockhash,
                                "Blocks must be connected in chain-order - the connected header must build on the last connected header");
-                       assert_eq!(best_block.height(), height - 1,
+                       assert_eq!(best_block.height, height - 1,
                                "Blocks must be connected in chain-order - the connected block height must be one greater than the previous height");
                }
 
@@ -8330,9 +8643,9 @@ where
                let new_height = height - 1;
                {
                        let mut best_block = self.best_block.write().unwrap();
-                       assert_eq!(best_block.block_hash(), header.block_hash(),
+                       assert_eq!(best_block.block_hash, header.block_hash(),
                                "Blocks must be disconnected in chain-order - the disconnected header must be the last connected header");
-                       assert_eq!(best_block.height(), height,
+                       assert_eq!(best_block.height, height,
                                "Blocks must be disconnected in chain-order - the disconnected block must have the correct height");
                        *best_block = BestBlock::new(header.prev_blockhash, new_height)
                }
@@ -8366,7 +8679,7 @@ where
                self.do_chain_event(Some(height), |channel| channel.transactions_confirmed(&block_hash, height, txdata, self.chain_hash, &self.node_signer, &self.default_configuration, &&WithChannelContext::from(&self.logger, &channel.context))
                        .map(|(a, b)| (a, Vec::new(), b)));
 
-               let last_best_block_height = self.best_block.read().unwrap().height();
+               let last_best_block_height = self.best_block.read().unwrap().height;
                if height < last_best_block_height {
                        let timestamp = self.highest_seen_timestamp.load(Ordering::Acquire);
                        self.do_chain_event(Some(last_best_block_height), |channel| channel.best_block_updated(last_best_block_height, timestamp as u32, self.chain_hash, &self.node_signer, &self.default_configuration, &&WithChannelContext::from(&self.logger, &channel.context)));
@@ -8474,6 +8787,9 @@ where
                                        match phase {
                                                // Retain unfunded channels.
                                                ChannelPhase::UnfundedOutboundV1(_) | ChannelPhase::UnfundedInboundV1(_) => true,
+                                               // TODO(dual_funding): Combine this match arm with above.
+                                               #[cfg(dual_funding)]
+                                               ChannelPhase::UnfundedOutboundV2(_) | ChannelPhase::UnfundedInboundV2(_) => true,
                                                ChannelPhase::Funded(channel) => {
                                                        let res = f(channel);
                                                        if let Ok((channel_ready_opt, mut timed_out_pending_htlcs, announcement_sigs)) = res {
@@ -8943,6 +9259,14 @@ where
                                                ChannelPhase::UnfundedInboundV1(chan) => {
                                                        &mut chan.context
                                                },
+                                               #[cfg(dual_funding)]
+                                               ChannelPhase::UnfundedOutboundV2(chan) => {
+                                                       &mut chan.context
+                                               },
+                                               #[cfg(dual_funding)]
+                                               ChannelPhase::UnfundedInboundV2(chan) => {
+                                                       &mut chan.context
+                                               },
                                        };
                                        // Clean up for removal.
                                        update_maps_on_chan_removal!(self, &context);
@@ -9055,7 +9379,7 @@ where
                                                let mut peer_state = e.get().lock().unwrap();
                                                peer_state.latest_features = init_msg.features.clone();
 
-                                               let best_block_height = self.best_block.read().unwrap().height();
+                                               let best_block_height = self.best_block.read().unwrap().height;
                                                if inbound_peer_limited &&
                                                        Self::unfunded_channel_count(&*peer_state, best_block_height) ==
                                                        peer_state.channel_by_id.len()
@@ -9095,12 +9419,30 @@ where
                                                        });
                                                }
 
+                                               // TODO(dual_funding): Combine this match arm with above once #[cfg(dual_funding)] is removed.
+                                               #[cfg(dual_funding)]
+                                               ChannelPhase::UnfundedOutboundV2(chan) => {
+                                                       pending_msg_events.push(events::MessageSendEvent::SendOpenChannelV2 {
+                                                               node_id: chan.context.get_counterparty_node_id(),
+                                                               msg: chan.get_open_channel_v2(self.chain_hash),
+                                                       });
+                                               },
+
                                                ChannelPhase::UnfundedInboundV1(_) => {
                                                        // Since unfunded inbound channel maps are cleared upon disconnecting a peer,
                                                        // they are not persisted and won't be recovered after a crash.
                                                        // Therefore, they shouldn't exist at this point.
                                                        debug_assert!(false);
                                                }
+
+                                               // TODO(dual_funding): Combine this match arm with above once #[cfg(dual_funding)] is removed.
+                                               #[cfg(dual_funding)]
+                                               ChannelPhase::UnfundedInboundV2(channel) => {
+                                                       // Since unfunded inbound channel maps are cleared upon disconnecting a peer,
+                                                       // they are not persisted and won't be recovered after a crash.
+                                                       // Therefore, they shouldn't exist at this point.
+                                                       debug_assert!(false);
+                                               },
                                        }
                                }
                        }
@@ -9112,8 +9454,6 @@ where
        }
 
        fn handle_error(&self, counterparty_node_id: &PublicKey, msg: &msgs::ErrorMessage) {
-               let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(self);
-
                match &msg.data as &str {
                        "cannot co-op close channel w/ active htlcs"|
                        "link failed to shutdown" =>
@@ -9126,34 +9466,45 @@ where
                                // We're not going to bother handling this in a sensible way, instead simply
                                // repeating the Shutdown message on repeat until morale improves.
                                if !msg.channel_id.is_zero() {
-                                       let per_peer_state = self.per_peer_state.read().unwrap();
-                                       let peer_state_mutex_opt = per_peer_state.get(counterparty_node_id);
-                                       if peer_state_mutex_opt.is_none() { return; }
-                                       let mut peer_state = peer_state_mutex_opt.unwrap().lock().unwrap();
-                                       if let Some(ChannelPhase::Funded(chan)) = peer_state.channel_by_id.get(&msg.channel_id) {
-                                               if let Some(msg) = chan.get_outbound_shutdown() {
-                                                       peer_state.pending_msg_events.push(events::MessageSendEvent::SendShutdown {
-                                                               node_id: *counterparty_node_id,
-                                                               msg,
-                                                       });
-                                               }
-                                               peer_state.pending_msg_events.push(events::MessageSendEvent::HandleError {
-                                                       node_id: *counterparty_node_id,
-                                                       action: msgs::ErrorAction::SendWarningMessage {
-                                                               msg: msgs::WarningMessage {
-                                                                       channel_id: msg.channel_id,
-                                                                       data: "You appear to be exhibiting LND bug 6039, we'll keep sending you shutdown messages until you handle them correctly".to_owned()
-                                                               },
-                                                               log_level: Level::Trace,
+                                       PersistenceNotifierGuard::optionally_notify(
+                                               self,
+                                               || -> NotifyOption {
+                                                       let per_peer_state = self.per_peer_state.read().unwrap();
+                                                       let peer_state_mutex_opt = per_peer_state.get(counterparty_node_id);
+                                                       if peer_state_mutex_opt.is_none() { return NotifyOption::SkipPersistNoEvents; }
+                                                       let mut peer_state = peer_state_mutex_opt.unwrap().lock().unwrap();
+                                                       if let Some(ChannelPhase::Funded(chan)) = peer_state.channel_by_id.get(&msg.channel_id) {
+                                                               if let Some(msg) = chan.get_outbound_shutdown() {
+                                                                       peer_state.pending_msg_events.push(events::MessageSendEvent::SendShutdown {
+                                                                               node_id: *counterparty_node_id,
+                                                                               msg,
+                                                                       });
+                                                               }
+                                                               peer_state.pending_msg_events.push(events::MessageSendEvent::HandleError {
+                                                                       node_id: *counterparty_node_id,
+                                                                       action: msgs::ErrorAction::SendWarningMessage {
+                                                                               msg: msgs::WarningMessage {
+                                                                                       channel_id: msg.channel_id,
+                                                                                       data: "You appear to be exhibiting LND bug 6039, we'll keep sending you shutdown messages until you handle them correctly".to_owned()
+                                                                               },
+                                                                               log_level: Level::Trace,
+                                                                       }
+                                                               });
+                                                               // This can happen in a fairly tight loop, so we absolutely cannot trigger
+                                                               // a `ChannelManager` write here.
+                                                               return NotifyOption::SkipPersistHandleEvents;
                                                        }
-                                               });
-                                       }
+                                                       NotifyOption::SkipPersistNoEvents
+                                               }
+                                       );
                                }
                                return;
                        }
                        _ => {}
                }
 
+               let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(self);
+
                if msg.channel_id.is_zero() {
                        let channel_ids: Vec<ChannelId> = {
                                let per_peer_state = self.per_peer_state.read().unwrap();
@@ -9178,14 +9529,29 @@ where
                                if peer_state_mutex_opt.is_none() { return; }
                                let mut peer_state_lock = peer_state_mutex_opt.unwrap().lock().unwrap();
                                let peer_state = &mut *peer_state_lock;
-                               if let Some(ChannelPhase::UnfundedOutboundV1(chan)) = peer_state.channel_by_id.get_mut(&msg.channel_id) {
-                                       if let Ok(msg) = chan.maybe_handle_error_without_close(self.chain_hash, &self.fee_estimator) {
-                                               peer_state.pending_msg_events.push(events::MessageSendEvent::SendOpenChannel {
-                                                       node_id: *counterparty_node_id,
-                                                       msg,
-                                               });
-                                               return;
-                                       }
+                               match peer_state.channel_by_id.get_mut(&msg.channel_id) {
+                                       Some(ChannelPhase::UnfundedOutboundV1(ref mut chan)) => {
+                                               if let Ok(msg) = chan.maybe_handle_error_without_close(self.chain_hash, &self.fee_estimator) {
+                                                       peer_state.pending_msg_events.push(events::MessageSendEvent::SendOpenChannel {
+                                                               node_id: *counterparty_node_id,
+                                                               msg,
+                                                       });
+                                                       return;
+                                               }
+                                       },
+                                       #[cfg(dual_funding)]
+                                       Some(ChannelPhase::UnfundedOutboundV2(ref mut chan)) => {
+                                               if let Ok(msg) = chan.maybe_handle_error_without_close(self.chain_hash, &self.fee_estimator) {
+                                                       peer_state.pending_msg_events.push(events::MessageSendEvent::SendOpenChannelV2 {
+                                                               node_id: *counterparty_node_id,
+                                                               msg,
+                                                       });
+                                                       return;
+                                               }
+                                       },
+                                       None | Some(ChannelPhase::UnfundedInboundV1(_) | ChannelPhase::Funded(_)) => (),
+                                       #[cfg(dual_funding)]
+                                       Some(ChannelPhase::UnfundedInboundV2(_)) => (),
                                }
                        }
 
@@ -9328,6 +9694,8 @@ where
                                        let builder = invoice_request.respond_using_derived_keys_no_std(
                                                payment_paths, payment_hash, created_at
                                        );
+                                       let builder: Result<InvoiceBuilder<DerivedSigningPubkey>, _> =
+                                               builder.map(|b| b.into());
                                        match builder.and_then(|b| b.allow_mpp().build_and_sign(secp_ctx)) {
                                                Ok(invoice) => Some(OffersMessage::Invoice(invoice)),
                                                Err(error) => Some(OffersMessage::InvoiceError(error.into())),
@@ -9339,18 +9707,25 @@ where
                                        let builder = invoice_request.respond_with_no_std(
                                                payment_paths, payment_hash, created_at
                                        );
+                                       let builder: Result<InvoiceBuilder<ExplicitSigningPubkey>, _> =
+                                               builder.map(|b| b.into());
                                        let response = builder.and_then(|builder| builder.allow_mpp().build())
                                                .map_err(|e| OffersMessage::InvoiceError(e.into()))
-                                               .and_then(|invoice|
-                                                       match invoice.sign(|invoice| self.node_signer.sign_bolt12_invoice(invoice)) {
+                                               .and_then(|invoice| {
+                                                       #[cfg(c_bindings)]
+                                                       let mut invoice = invoice;
+                                                       match invoice.sign(|invoice: &UnsignedBolt12Invoice|
+                                                               self.node_signer.sign_bolt12_invoice(invoice)
+                                                       ) {
                                                                Ok(invoice) => Ok(OffersMessage::Invoice(invoice)),
-                                                               Err(SignError::Signing(())) => Err(OffersMessage::InvoiceError(
+                                                               Err(SignError::Signing) => Err(OffersMessage::InvoiceError(
                                                                                InvoiceError::from_string("Failed signing invoice".to_string())
                                                                )),
                                                                Err(SignError::Verification(_)) => Err(OffersMessage::InvoiceError(
                                                                                InvoiceError::from_string("Failed invoice signature verification".to_string())
                                                                )),
-                                                       });
+                                                       }
+                                               });
                                        match response {
                                                Ok(invoice) => Some(invoice),
                                                Err(error) => Some(error),
@@ -9612,6 +9987,7 @@ impl_writeable_tlv_based_enum!(PendingHTLCRouting,
        },
        (2, ReceiveKeysend) => {
                (0, payment_preimage, required),
+               (1, requires_blinded_error, (default_value, false)),
                (2, incoming_cltv_expiry, required),
                (3, payment_metadata, option),
                (4, payment_data, option), // Added in 0.0.116
@@ -9964,8 +10340,8 @@ where
                self.chain_hash.write(writer)?;
                {
                        let best_block = self.best_block.read().unwrap();
-                       best_block.height().write(writer)?;
-                       best_block.block_hash().write(writer)?;
+                       best_block.height.write(writer)?;
+                       best_block.block_hash.write(writer)?;
                }
 
                let mut serializable_peer_count: u64 = 0;
@@ -10011,6 +10387,12 @@ where
                        }
                }
 
+               let mut decode_update_add_htlcs_opt = None;
+               let decode_update_add_htlcs = self.decode_update_add_htlcs.lock().unwrap();
+               if !decode_update_add_htlcs.is_empty() {
+                       decode_update_add_htlcs_opt = Some(decode_update_add_htlcs);
+               }
+
                let per_peer_state = self.per_peer_state.write().unwrap();
 
                let pending_inbound_payments = self.pending_inbound_payments.lock().unwrap();
@@ -10162,6 +10544,7 @@ where
                        (10, in_flight_monitor_updates, option),
                        (11, self.probing_cookie_secret, required),
                        (13, htlc_onion_fields, optional_vec),
+                       (14, decode_update_add_htlcs_opt, option),
                });
 
                Ok(())
@@ -10627,6 +11010,7 @@ where
                let mut monitor_update_blocked_actions_per_peer: Option<Vec<(_, BTreeMap<_, Vec<_>>)>> = Some(Vec::new());
                let mut events_override = None;
                let mut in_flight_monitor_updates: Option<HashMap<(PublicKey, OutPoint), Vec<ChannelMonitorUpdate>>> = None;
+               let mut decode_update_add_htlcs: Option<HashMap<u64, Vec<msgs::UpdateAddHTLC>>> = None;
                read_tlv_fields!(reader, {
                        (1, pending_outbound_payments_no_retry, option),
                        (2, pending_intercepted_htlcs, option),
@@ -10640,7 +11024,9 @@ where
                        (10, in_flight_monitor_updates, option),
                        (11, probing_cookie_secret, option),
                        (13, claimable_htlc_onion_fields, optional_vec),
+                       (14, decode_update_add_htlcs, option),
                });
+               let mut decode_update_add_htlcs = decode_update_add_htlcs.unwrap_or_else(|| new_hash_map());
                if fake_scid_rand_bytes.is_none() {
                        fake_scid_rand_bytes = Some(args.entropy_source.get_secure_random_bytes());
                }
@@ -10860,6 +11246,18 @@ where
                                                                // still have an entry for this HTLC in `forward_htlcs` or
                                                                // `pending_intercepted_htlcs`, we were apparently not persisted after
                                                                // the monitor was when forwarding the payment.
+                                                               decode_update_add_htlcs.retain(|scid, update_add_htlcs| {
+                                                                       update_add_htlcs.retain(|update_add_htlc| {
+                                                                               let matches = *scid == prev_hop_data.short_channel_id &&
+                                                                                       update_add_htlc.htlc_id == prev_hop_data.htlc_id;
+                                                                               if matches {
+                                                                                       log_info!(logger, "Removing pending to-decode HTLC with hash {} as it was forwarded to the closed channel {}",
+                                                                                               &htlc.payment_hash, &monitor.channel_id());
+                                                                               }
+                                                                               !matches
+                                                                       });
+                                                                       !update_add_htlcs.is_empty()
+                                                               });
                                                                forward_htlcs.retain(|_, forwards| {
                                                                        forwards.retain(|forward| {
                                                                                if let HTLCForwardInfo::AddHTLC(htlc_info) = forward {
@@ -10941,7 +11339,7 @@ where
                        }
                }
 
-               if !forward_htlcs.is_empty() || pending_outbounds.needs_abandon() {
+               if !forward_htlcs.is_empty() || !decode_update_add_htlcs.is_empty() || pending_outbounds.needs_abandon() {
                        // If we have pending HTLCs to forward, assume we either dropped a
                        // `PendingHTLCsForwardable` or the user received it but never processed it as they
                        // shut down before the timer hit. Either way, set the time_forwardable to a small
@@ -11175,6 +11573,7 @@ where
                        pending_intercepted_htlcs: Mutex::new(pending_intercepted_htlcs.unwrap()),
 
                        forward_htlcs: Mutex::new(forward_htlcs),
+                       decode_update_add_htlcs: Mutex::new(decode_update_add_htlcs),
                        claimable_payments: Mutex::new(ClaimablePayments { claimable_payments, pending_claiming_payments: pending_claiming_payments.unwrap() }),
                        outbound_scid_aliases: Mutex::new(outbound_scid_aliases),
                        outpoint_to_peer: Mutex::new(outpoint_to_peer),
@@ -11223,7 +11622,9 @@ where
                        // don't remember in the `ChannelMonitor` where we got a preimage from, but if the
                        // channel is closed we just assume that it probably came from an on-chain claim.
                        channel_manager.claim_funds_internal(source, preimage, Some(downstream_value), None,
-                               downstream_closed, true, downstream_node_id, downstream_funding, downstream_channel_id);
+                               downstream_closed, true, downstream_node_id, downstream_funding,
+                               downstream_channel_id, None
+                       );
                }
 
                //TODO: Broadcast channel update for closed channels, but only after we've made a
@@ -12247,7 +12648,7 @@ mod tests {
                };
                // Check that if the amount we received + the penultimate hop extra fee is less than the sender
                // intended amount, we fail the payment.
-               let current_height: u32 = node[0].node.best_block.read().unwrap().height();
+               let current_height: u32 = node[0].node.best_block.read().unwrap().height;
                if let Err(crate::ln::channelmanager::InboundHTLCErr { err_code, .. }) =
                        create_recv_pending_htlc_info(hop_data, [0; 32], PaymentHash([0; 32]),
                                sender_intended_amt_msat - extra_fee_msat - 1, 42, None, true, Some(extra_fee_msat),
@@ -12267,7 +12668,7 @@ mod tests {
                        }),
                        custom_tlvs: Vec::new(),
                };
-               let current_height: u32 = node[0].node.best_block.read().unwrap().height();
+               let current_height: u32 = node[0].node.best_block.read().unwrap().height;
                assert!(create_recv_pending_htlc_info(hop_data, [0; 32], PaymentHash([0; 32]),
                        sender_intended_amt_msat - extra_fee_msat, 42, None, true, Some(extra_fee_msat),
                        current_height, node[0].node.default_configuration.accept_mpp_keysend).is_ok());
@@ -12280,7 +12681,7 @@ mod tests {
                let node_chanmgr = create_node_chanmgrs(1, &node_cfg, &[None]);
                let node = create_network(1, &node_cfg, &node_chanmgr);
 
-               let current_height: u32 = node[0].node.best_block.read().unwrap().height();
+               let current_height: u32 = node[0].node.best_block.read().unwrap().height;
                let result = create_recv_pending_htlc_info(msgs::InboundOnionPayload::Receive {
                        sender_intended_htlc_amt_msat: 100,
                        cltv_expiry_height: 22,
@@ -12706,7 +13107,7 @@ pub mod bench {
 
                assert_eq!(&tx_broadcaster.txn_broadcasted.lock().unwrap()[..], &[tx.clone()]);
 
-               let block = create_dummy_block(BestBlock::from_network(network).block_hash(), 42, vec![tx]);
+               let block = create_dummy_block(BestBlock::from_network(network).block_hash, 42, vec![tx]);
                Listen::block_connected(&node_a, &block, 1);
                Listen::block_connected(&node_b, &block, 1);