Fix `cmp::max` execution in `ChannelContext::get_dust_buffer_feerate`
[rust-lightning] / lightning / src / ln / channel.rs
index 2ae44fb0eb0386ac41c4a29715ee8be72c39a009..58d35a1a95a4ddfc05b29d7fcfe4db5bdf6e89a7 100644 (file)
@@ -50,7 +50,6 @@ use crate::util::scid_utils::scid_from_parts;
 use crate::io;
 use crate::prelude::*;
 use core::{cmp,mem,fmt};
-use core::convert::TryInto;
 use core::ops::Deref;
 #[cfg(any(test, fuzzing, debug_assertions))]
 use crate::sync::Mutex;
@@ -104,10 +103,38 @@ enum InboundHTLCRemovalReason {
        Fulfill(PaymentPreimage),
 }
 
+/// Represents the resolution status of an inbound HTLC.
+#[derive(Clone)]
+enum InboundHTLCResolution {
+       /// Resolved implies the action we must take with the inbound HTLC has already been determined,
+       /// i.e., we already know whether it must be failed back or forwarded.
+       //
+       // TODO: Once this variant is removed, we should also clean up
+       // [`MonitorRestoreUpdates::accepted_htlcs`] as the path will be unreachable.
+       Resolved {
+               pending_htlc_status: PendingHTLCStatus,
+       },
+       /// Pending implies we will attempt to resolve the inbound HTLC once it has been fully committed
+       /// to by both sides of the channel, i.e., once a `revoke_and_ack` has been processed by both
+       /// nodes for the state update in which it was proposed.
+       Pending {
+               update_add_htlc: msgs::UpdateAddHTLC,
+       },
+}
+
+impl_writeable_tlv_based_enum!(InboundHTLCResolution,
+       (0, Resolved) => {
+               (0, pending_htlc_status, required),
+       },
+       (2, Pending) => {
+               (0, update_add_htlc, required),
+       };
+);
+
 enum InboundHTLCState {
        /// Offered by remote, to be included in next local commitment tx. I.e., the remote sent an
        /// update_add_htlc message for this HTLC.
-       RemoteAnnounced(PendingHTLCStatus),
+       RemoteAnnounced(InboundHTLCResolution),
        /// Included in a received commitment_signed message (implying we've
        /// revoke_and_ack'd it), but the remote hasn't yet revoked their previous
        /// state (see the example below). We have not yet included this HTLC in a
@@ -137,13 +164,13 @@ enum InboundHTLCState {
        /// Implies AwaitingRemoteRevoke.
        ///
        /// [BOLT #2]: https://github.com/lightning/bolts/blob/master/02-peer-protocol.md
-       AwaitingRemoteRevokeToAnnounce(PendingHTLCStatus),
+       AwaitingRemoteRevokeToAnnounce(InboundHTLCResolution),
        /// Included in a received commitment_signed message (implying we've revoke_and_ack'd it).
        /// We have also included this HTLC in our latest commitment_signed and are now just waiting
        /// on the remote's revoke_and_ack to make this HTLC an irrevocable part of the state of the
        /// channel (before it can then get forwarded and/or removed).
        /// Implies AwaitingRemoteRevoke.
-       AwaitingAnnouncedRemoteRevoke(PendingHTLCStatus),
+       AwaitingAnnouncedRemoteRevoke(InboundHTLCResolution),
        Committed,
        /// Removed by us and a new commitment_signed was sent (if we were AwaitingRemoteRevoke when we
        /// created it we would have put it in the holding cell instead). When they next revoke_and_ack
@@ -1044,6 +1071,7 @@ pub(super) struct MonitorRestoreUpdates {
        pub accepted_htlcs: Vec<(PendingHTLCInfo, u64)>,
        pub failed_htlcs: Vec<(HTLCSource, PaymentHash, HTLCFailReason)>,
        pub finalized_claimed_htlcs: Vec<HTLCSource>,
+       pub pending_update_adds: Vec<msgs::UpdateAddHTLC>,
        pub funding_broadcastable: Option<Transaction>,
        pub channel_ready: Option<msgs::ChannelReady>,
        pub announcement_sigs: Option<msgs::AnnouncementSignatures>,
@@ -1161,6 +1189,10 @@ impl_writeable_tlv_based!(PendingChannelMonitorUpdate, {
 pub(super) enum ChannelPhase<SP: Deref> where SP::Target: SignerProvider {
        UnfundedOutboundV1(OutboundV1Channel<SP>),
        UnfundedInboundV1(InboundV1Channel<SP>),
+       #[cfg(dual_funding)]
+       UnfundedOutboundV2(OutboundV2Channel<SP>),
+       #[cfg(dual_funding)]
+       UnfundedInboundV2(InboundV2Channel<SP>),
        Funded(Channel<SP>),
 }
 
@@ -1173,6 +1205,10 @@ impl<'a, SP: Deref> ChannelPhase<SP> where
                        ChannelPhase::Funded(chan) => &chan.context,
                        ChannelPhase::UnfundedOutboundV1(chan) => &chan.context,
                        ChannelPhase::UnfundedInboundV1(chan) => &chan.context,
+                       #[cfg(dual_funding)]
+                       ChannelPhase::UnfundedOutboundV2(chan) => &chan.context,
+                       #[cfg(dual_funding)]
+                       ChannelPhase::UnfundedInboundV2(chan) => &chan.context,
                }
        }
 
@@ -1181,6 +1217,10 @@ impl<'a, SP: Deref> ChannelPhase<SP> where
                        ChannelPhase::Funded(ref mut chan) => &mut chan.context,
                        ChannelPhase::UnfundedOutboundV1(ref mut chan) => &mut chan.context,
                        ChannelPhase::UnfundedInboundV1(ref mut chan) => &mut chan.context,
+                       #[cfg(dual_funding)]
+                       ChannelPhase::UnfundedOutboundV2(ref mut chan) => &mut chan.context,
+                       #[cfg(dual_funding)]
+                       ChannelPhase::UnfundedInboundV2(ref mut chan) => &mut chan.context,
                }
        }
 }
@@ -1279,6 +1319,7 @@ pub(super) struct ChannelContext<SP: Deref> where SP::Target: SignerProvider {
        monitor_pending_forwards: Vec<(PendingHTLCInfo, u64)>,
        monitor_pending_failures: Vec<(HTLCSource, PaymentHash, HTLCFailReason)>,
        monitor_pending_finalized_fulfills: Vec<HTLCSource>,
+       monitor_pending_update_adds: Vec<msgs::UpdateAddHTLC>,
 
        /// If we went to send a commitment update (ie some messages then [`msgs::CommitmentSigned`])
        /// but our signer (initially) refused to give us a signature, we should retry at some point in
@@ -1503,6 +1544,557 @@ pub(super) struct ChannelContext<SP: Deref> where SP::Target: SignerProvider {
 }
 
 impl<SP: Deref> ChannelContext<SP> where SP::Target: SignerProvider  {
+       fn new_for_inbound_channel<'a, ES: Deref, F: Deref, L: Deref>(
+               fee_estimator: &'a LowerBoundedFeeEstimator<F>,
+               entropy_source: &'a ES,
+               signer_provider: &'a SP,
+               counterparty_node_id: PublicKey,
+               their_features: &'a InitFeatures,
+               user_id: u128,
+               config: &'a UserConfig,
+               current_chain_height: u32,
+               logger: &'a L,
+               is_0conf: bool,
+               our_funding_satoshis: u64,
+               counterparty_pubkeys: ChannelPublicKeys,
+               channel_type: ChannelTypeFeatures,
+               holder_selected_channel_reserve_satoshis: u64,
+               msg_channel_reserve_satoshis: u64,
+               msg_push_msat: u64,
+               open_channel_fields: msgs::CommonOpenChannelFields,
+       ) -> Result<ChannelContext<SP>, ChannelError>
+               where
+                       ES::Target: EntropySource,
+                       F::Target: FeeEstimator,
+                       L::Target: Logger,
+                       SP::Target: SignerProvider,
+       {
+               let logger = WithContext::from(logger, Some(counterparty_node_id), Some(open_channel_fields.temporary_channel_id));
+               let announced_channel = if (open_channel_fields.channel_flags & 1) == 1 { true } else { false };
+
+               let channel_value_satoshis = our_funding_satoshis.saturating_add(open_channel_fields.funding_satoshis);
+
+               let channel_keys_id = signer_provider.generate_channel_keys_id(true, channel_value_satoshis, user_id);
+               let holder_signer = signer_provider.derive_channel_signer(channel_value_satoshis, channel_keys_id);
+               let pubkeys = holder_signer.pubkeys().clone();
+
+               if config.channel_handshake_config.our_to_self_delay < BREAKDOWN_TIMEOUT {
+                       return Err(ChannelError::Close(format!("Configured with an unreasonable our_to_self_delay ({}) putting user funds at risks. It must be greater than {}", config.channel_handshake_config.our_to_self_delay, BREAKDOWN_TIMEOUT)));
+               }
+
+               // Check sanity of message fields:
+               if channel_value_satoshis > config.channel_handshake_limits.max_funding_satoshis {
+                       return Err(ChannelError::Close(format!(
+                               "Per our config, funding must be at most {}. It was {}. Peer contribution: {}. Our contribution: {}",
+                               config.channel_handshake_limits.max_funding_satoshis, channel_value_satoshis,
+                               open_channel_fields.funding_satoshis, our_funding_satoshis)));
+               }
+               if channel_value_satoshis >= TOTAL_BITCOIN_SUPPLY_SATOSHIS {
+                       return Err(ChannelError::Close(format!("Funding must be smaller than the total bitcoin supply. It was {}", channel_value_satoshis)));
+               }
+               if msg_channel_reserve_satoshis > channel_value_satoshis {
+                       return Err(ChannelError::Close(format!("Bogus channel_reserve_satoshis ({}). Must be no greater than channel_value_satoshis: {}", msg_channel_reserve_satoshis, channel_value_satoshis)));
+               }
+               let full_channel_value_msat = (channel_value_satoshis - msg_channel_reserve_satoshis) * 1000;
+               if msg_push_msat > full_channel_value_msat {
+                       return Err(ChannelError::Close(format!("push_msat {} was larger than channel amount minus reserve ({})", msg_push_msat, full_channel_value_msat)));
+               }
+               if open_channel_fields.dust_limit_satoshis > channel_value_satoshis {
+                       return Err(ChannelError::Close(format!("dust_limit_satoshis {} was larger than channel_value_satoshis {}. Peer never wants payout outputs?", open_channel_fields.dust_limit_satoshis, channel_value_satoshis)));
+               }
+               if open_channel_fields.htlc_minimum_msat >= full_channel_value_msat {
+                       return Err(ChannelError::Close(format!("Minimum htlc value ({}) was larger than full channel value ({})", open_channel_fields.htlc_minimum_msat, full_channel_value_msat)));
+               }
+               Channel::<SP>::check_remote_fee(&channel_type, fee_estimator, open_channel_fields.commitment_feerate_sat_per_1000_weight, None, &&logger)?;
+
+               let max_counterparty_selected_contest_delay = u16::min(config.channel_handshake_limits.their_to_self_delay, MAX_LOCAL_BREAKDOWN_TIMEOUT);
+               if open_channel_fields.to_self_delay > max_counterparty_selected_contest_delay {
+                       return Err(ChannelError::Close(format!("They wanted our payments to be delayed by a needlessly long period. Upper limit: {}. Actual: {}", max_counterparty_selected_contest_delay, open_channel_fields.to_self_delay)));
+               }
+               if open_channel_fields.max_accepted_htlcs < 1 {
+                       return Err(ChannelError::Close("0 max_accepted_htlcs makes for a useless channel".to_owned()));
+               }
+               if open_channel_fields.max_accepted_htlcs > MAX_HTLCS {
+                       return Err(ChannelError::Close(format!("max_accepted_htlcs was {}. It must not be larger than {}", open_channel_fields.max_accepted_htlcs, MAX_HTLCS)));
+               }
+
+               // Now check against optional parameters as set by config...
+               if channel_value_satoshis < config.channel_handshake_limits.min_funding_satoshis {
+                       return Err(ChannelError::Close(format!("Funding satoshis ({}) is less than the user specified limit ({})", channel_value_satoshis, config.channel_handshake_limits.min_funding_satoshis)));
+               }
+               if open_channel_fields.htlc_minimum_msat > config.channel_handshake_limits.max_htlc_minimum_msat {
+                       return Err(ChannelError::Close(format!("htlc_minimum_msat ({}) is higher than the user specified limit ({})", open_channel_fields.htlc_minimum_msat, config.channel_handshake_limits.max_htlc_minimum_msat)));
+               }
+               if open_channel_fields.max_htlc_value_in_flight_msat < config.channel_handshake_limits.min_max_htlc_value_in_flight_msat {
+                       return Err(ChannelError::Close(format!("max_htlc_value_in_flight_msat ({}) is less than the user specified limit ({})", open_channel_fields.max_htlc_value_in_flight_msat, config.channel_handshake_limits.min_max_htlc_value_in_flight_msat)));
+               }
+               if msg_channel_reserve_satoshis > config.channel_handshake_limits.max_channel_reserve_satoshis {
+                       return Err(ChannelError::Close(format!("channel_reserve_satoshis ({}) is higher than the user specified limit ({})", msg_channel_reserve_satoshis, config.channel_handshake_limits.max_channel_reserve_satoshis)));
+               }
+               if open_channel_fields.max_accepted_htlcs < config.channel_handshake_limits.min_max_accepted_htlcs {
+                       return Err(ChannelError::Close(format!("max_accepted_htlcs ({}) is less than the user specified limit ({})", open_channel_fields.max_accepted_htlcs, config.channel_handshake_limits.min_max_accepted_htlcs)));
+               }
+               if open_channel_fields.dust_limit_satoshis < MIN_CHAN_DUST_LIMIT_SATOSHIS {
+                       return Err(ChannelError::Close(format!("dust_limit_satoshis ({}) is less than the implementation limit ({})", open_channel_fields.dust_limit_satoshis, MIN_CHAN_DUST_LIMIT_SATOSHIS)));
+               }
+               if open_channel_fields.dust_limit_satoshis >  MAX_CHAN_DUST_LIMIT_SATOSHIS {
+                       return Err(ChannelError::Close(format!("dust_limit_satoshis ({}) is greater than the implementation limit ({})", open_channel_fields.dust_limit_satoshis, MAX_CHAN_DUST_LIMIT_SATOSHIS)));
+               }
+
+               // Convert things into internal flags and prep our state:
+
+               if config.channel_handshake_limits.force_announced_channel_preference {
+                       if config.channel_handshake_config.announced_channel != announced_channel {
+                               return Err(ChannelError::Close("Peer tried to open channel but their announcement preference is different from ours".to_owned()));
+                       }
+               }
+
+               if holder_selected_channel_reserve_satoshis < MIN_CHAN_DUST_LIMIT_SATOSHIS {
+                       // Protocol level safety check in place, although it should never happen because
+                       // of `MIN_THEIR_CHAN_RESERVE_SATOSHIS`
+                       return Err(ChannelError::Close(format!("Suitable channel reserve not found. remote_channel_reserve was ({}). dust_limit_satoshis is ({}).", holder_selected_channel_reserve_satoshis, MIN_CHAN_DUST_LIMIT_SATOSHIS)));
+               }
+               if holder_selected_channel_reserve_satoshis * 1000 >= full_channel_value_msat {
+                       return Err(ChannelError::Close(format!("Suitable channel reserve not found. remote_channel_reserve was ({})msats. Channel value is ({} - {})msats.", holder_selected_channel_reserve_satoshis * 1000, full_channel_value_msat, msg_push_msat)));
+               }
+               if msg_channel_reserve_satoshis < MIN_CHAN_DUST_LIMIT_SATOSHIS {
+                       log_debug!(logger, "channel_reserve_satoshis ({}) is smaller than our dust limit ({}). We can broadcast stale states without any risk, implying this channel is very insecure for our counterparty.",
+                               msg_channel_reserve_satoshis, MIN_CHAN_DUST_LIMIT_SATOSHIS);
+               }
+               if holder_selected_channel_reserve_satoshis < open_channel_fields.dust_limit_satoshis {
+                       return Err(ChannelError::Close(format!("Dust limit ({}) too high for the channel reserve we require the remote to keep ({})", open_channel_fields.dust_limit_satoshis, holder_selected_channel_reserve_satoshis)));
+               }
+
+               // check if the funder's amount for the initial commitment tx is sufficient
+               // for full fee payment plus a few HTLCs to ensure the channel will be useful.
+               let anchor_outputs_value = if channel_type.supports_anchors_zero_fee_htlc_tx() {
+                       ANCHOR_OUTPUT_VALUE_SATOSHI * 2
+               } else {
+                       0
+               };
+               let funders_amount_msat = open_channel_fields.funding_satoshis * 1000 - msg_push_msat;
+               let commitment_tx_fee = commit_tx_fee_msat(open_channel_fields.commitment_feerate_sat_per_1000_weight, MIN_AFFORDABLE_HTLC_COUNT, &channel_type) / 1000;
+               if (funders_amount_msat / 1000).saturating_sub(anchor_outputs_value) < commitment_tx_fee {
+                       return Err(ChannelError::Close(format!("Funding amount ({} sats) can't even pay fee for initial commitment transaction fee of {} sats.", (funders_amount_msat / 1000).saturating_sub(anchor_outputs_value), commitment_tx_fee)));
+               }
+
+               let to_remote_satoshis = funders_amount_msat / 1000 - commitment_tx_fee - anchor_outputs_value;
+               // While it's reasonable for us to not meet the channel reserve initially (if they don't
+               // want to push much to us), our counterparty should always have more than our reserve.
+               if to_remote_satoshis < holder_selected_channel_reserve_satoshis {
+                       return Err(ChannelError::Close("Insufficient funding amount for initial reserve".to_owned()));
+               }
+
+               let counterparty_shutdown_scriptpubkey = if their_features.supports_upfront_shutdown_script() {
+                       match &open_channel_fields.shutdown_scriptpubkey {
+                               &Some(ref script) => {
+                                       // Peer is signaling upfront_shutdown and has opt-out with a 0-length script. We don't enforce anything
+                                       if script.len() == 0 {
+                                               None
+                                       } else {
+                                               if !script::is_bolt2_compliant(&script, their_features) {
+                                                       return Err(ChannelError::Close(format!("Peer is signaling upfront_shutdown but has provided an unacceptable scriptpubkey format: {}", script)))
+                                               }
+                                               Some(script.clone())
+                                       }
+                               },
+                               // Peer is signaling upfront shutdown but don't opt-out with correct mechanism (a.k.a 0-length script). Peer looks buggy, we fail the channel
+                               &None => {
+                                       return Err(ChannelError::Close("Peer is signaling upfront_shutdown but we don't get any script. Use 0-length script to opt-out".to_owned()));
+                               }
+                       }
+               } else { None };
+
+               let shutdown_scriptpubkey = if config.channel_handshake_config.commit_upfront_shutdown_pubkey {
+                       match signer_provider.get_shutdown_scriptpubkey() {
+                               Ok(scriptpubkey) => Some(scriptpubkey),
+                               Err(_) => return Err(ChannelError::Close("Failed to get upfront shutdown scriptpubkey".to_owned())),
+                       }
+               } else { None };
+
+               if let Some(shutdown_scriptpubkey) = &shutdown_scriptpubkey {
+                       if !shutdown_scriptpubkey.is_compatible(&their_features) {
+                               return Err(ChannelError::Close(format!("Provided a scriptpubkey format not accepted by peer: {}", shutdown_scriptpubkey)));
+                       }
+               }
+
+               let destination_script = match signer_provider.get_destination_script(channel_keys_id) {
+                       Ok(script) => script,
+                       Err(_) => return Err(ChannelError::Close("Failed to get destination script".to_owned())),
+               };
+
+               let mut secp_ctx = Secp256k1::new();
+               secp_ctx.seeded_randomize(&entropy_source.get_secure_random_bytes());
+
+               let minimum_depth = if is_0conf {
+                       Some(0)
+               } else {
+                       Some(cmp::max(config.channel_handshake_config.minimum_depth, 1))
+               };
+
+               let value_to_self_msat = our_funding_satoshis * 1000 + msg_push_msat;
+
+               // TODO(dual_funding): Checks for `funding_feerate_sat_per_1000_weight`?
+
+               let channel_context = ChannelContext {
+                       user_id,
+
+                       config: LegacyChannelConfig {
+                               options: config.channel_config.clone(),
+                               announced_channel,
+                               commit_upfront_shutdown_pubkey: config.channel_handshake_config.commit_upfront_shutdown_pubkey,
+                       },
+
+                       prev_config: None,
+
+                       inbound_handshake_limits_override: None,
+
+                       temporary_channel_id: Some(open_channel_fields.temporary_channel_id),
+                       channel_id: open_channel_fields.temporary_channel_id,
+                       channel_state: ChannelState::NegotiatingFunding(
+                               NegotiatingFundingFlags::OUR_INIT_SENT | NegotiatingFundingFlags::THEIR_INIT_SENT
+                       ),
+                       announcement_sigs_state: AnnouncementSigsState::NotSent,
+                       secp_ctx,
+
+                       latest_monitor_update_id: 0,
+
+                       holder_signer: ChannelSignerType::Ecdsa(holder_signer),
+                       shutdown_scriptpubkey,
+                       destination_script,
+
+                       cur_holder_commitment_transaction_number: INITIAL_COMMITMENT_NUMBER,
+                       cur_counterparty_commitment_transaction_number: INITIAL_COMMITMENT_NUMBER,
+                       value_to_self_msat,
+
+                       pending_inbound_htlcs: Vec::new(),
+                       pending_outbound_htlcs: Vec::new(),
+                       holding_cell_htlc_updates: Vec::new(),
+                       pending_update_fee: None,
+                       holding_cell_update_fee: None,
+                       next_holder_htlc_id: 0,
+                       next_counterparty_htlc_id: 0,
+                       update_time_counter: 1,
+
+                       resend_order: RAACommitmentOrder::CommitmentFirst,
+
+                       monitor_pending_channel_ready: false,
+                       monitor_pending_revoke_and_ack: false,
+                       monitor_pending_commitment_signed: false,
+                       monitor_pending_forwards: Vec::new(),
+                       monitor_pending_failures: Vec::new(),
+                       monitor_pending_finalized_fulfills: Vec::new(),
+                       monitor_pending_update_adds: Vec::new(),
+
+                       signer_pending_commitment_update: false,
+                       signer_pending_funding: false,
+
+
+                       #[cfg(debug_assertions)]
+                       holder_max_commitment_tx_output: Mutex::new((value_to_self_msat, (channel_value_satoshis * 1000 - msg_push_msat).saturating_sub(value_to_self_msat))),
+                       #[cfg(debug_assertions)]
+                       counterparty_max_commitment_tx_output: Mutex::new((value_to_self_msat, (channel_value_satoshis * 1000 - msg_push_msat).saturating_sub(value_to_self_msat))),
+
+                       last_sent_closing_fee: None,
+                       pending_counterparty_closing_signed: None,
+                       expecting_peer_commitment_signed: false,
+                       closing_fee_limits: None,
+                       target_closing_feerate_sats_per_kw: None,
+
+                       funding_tx_confirmed_in: None,
+                       funding_tx_confirmation_height: 0,
+                       short_channel_id: None,
+                       channel_creation_height: current_chain_height,
+
+                       feerate_per_kw: open_channel_fields.commitment_feerate_sat_per_1000_weight,
+                       channel_value_satoshis,
+                       counterparty_dust_limit_satoshis: open_channel_fields.dust_limit_satoshis,
+                       holder_dust_limit_satoshis: MIN_CHAN_DUST_LIMIT_SATOSHIS,
+                       counterparty_max_htlc_value_in_flight_msat: cmp::min(open_channel_fields.max_htlc_value_in_flight_msat, channel_value_satoshis * 1000),
+                       holder_max_htlc_value_in_flight_msat: get_holder_max_htlc_value_in_flight_msat(channel_value_satoshis, &config.channel_handshake_config),
+                       counterparty_selected_channel_reserve_satoshis: Some(msg_channel_reserve_satoshis),
+                       holder_selected_channel_reserve_satoshis,
+                       counterparty_htlc_minimum_msat: open_channel_fields.htlc_minimum_msat,
+                       holder_htlc_minimum_msat: if config.channel_handshake_config.our_htlc_minimum_msat == 0 { 1 } else { config.channel_handshake_config.our_htlc_minimum_msat },
+                       counterparty_max_accepted_htlcs: open_channel_fields.max_accepted_htlcs,
+                       holder_max_accepted_htlcs: cmp::min(config.channel_handshake_config.our_max_accepted_htlcs, MAX_HTLCS),
+                       minimum_depth,
+
+                       counterparty_forwarding_info: None,
+
+                       channel_transaction_parameters: ChannelTransactionParameters {
+                               holder_pubkeys: pubkeys,
+                               holder_selected_contest_delay: config.channel_handshake_config.our_to_self_delay,
+                               is_outbound_from_holder: false,
+                               counterparty_parameters: Some(CounterpartyChannelTransactionParameters {
+                                       selected_contest_delay: open_channel_fields.to_self_delay,
+                                       pubkeys: counterparty_pubkeys,
+                               }),
+                               funding_outpoint: None,
+                               channel_type_features: channel_type.clone()
+                       },
+                       funding_transaction: None,
+                       is_batch_funding: None,
+
+                       counterparty_cur_commitment_point: Some(open_channel_fields.first_per_commitment_point),
+                       counterparty_prev_commitment_point: None,
+                       counterparty_node_id,
+
+                       counterparty_shutdown_scriptpubkey,
+
+                       commitment_secrets: CounterpartyCommitmentSecrets::new(),
+
+                       channel_update_status: ChannelUpdateStatus::Enabled,
+                       closing_signed_in_flight: false,
+
+                       announcement_sigs: None,
+
+                       #[cfg(any(test, fuzzing))]
+                       next_local_commitment_tx_fee_info_cached: Mutex::new(None),
+                       #[cfg(any(test, fuzzing))]
+                       next_remote_commitment_tx_fee_info_cached: Mutex::new(None),
+
+                       workaround_lnd_bug_4006: None,
+                       sent_message_awaiting_response: None,
+
+                       latest_inbound_scid_alias: None,
+                       outbound_scid_alias: 0,
+
+                       channel_pending_event_emitted: false,
+                       channel_ready_event_emitted: false,
+
+                       #[cfg(any(test, fuzzing))]
+                       historical_inbound_htlc_fulfills: new_hash_set(),
+
+                       channel_type,
+                       channel_keys_id,
+
+                       local_initiated_shutdown: None,
+
+                       blocked_monitor_updates: Vec::new(),
+               };
+
+               Ok(channel_context)
+       }
+
+       fn new_for_outbound_channel<'a, ES: Deref, F: Deref>(
+               fee_estimator: &'a LowerBoundedFeeEstimator<F>,
+               entropy_source: &'a ES,
+               signer_provider: &'a SP,
+               counterparty_node_id: PublicKey,
+               their_features: &'a InitFeatures,
+               funding_satoshis: u64,
+               push_msat: u64,
+               user_id: u128,
+               config: &'a UserConfig,
+               current_chain_height: u32,
+               outbound_scid_alias: u64,
+               temporary_channel_id: Option<ChannelId>,
+               holder_selected_channel_reserve_satoshis: u64,
+               channel_keys_id: [u8; 32],
+               holder_signer: <SP::Target as SignerProvider>::EcdsaSigner,
+               pubkeys: ChannelPublicKeys,
+       ) -> Result<ChannelContext<SP>, APIError>
+               where
+                       ES::Target: EntropySource,
+                       F::Target: FeeEstimator,
+                       SP::Target: SignerProvider,
+       {
+               // This will be updated with the counterparty contribution if this is a dual-funded channel
+               let channel_value_satoshis = funding_satoshis;
+
+               let holder_selected_contest_delay = config.channel_handshake_config.our_to_self_delay;
+
+               if !their_features.supports_wumbo() && channel_value_satoshis > MAX_FUNDING_SATOSHIS_NO_WUMBO {
+                       return Err(APIError::APIMisuseError{err: format!("funding_value must not exceed {}, it was {}", MAX_FUNDING_SATOSHIS_NO_WUMBO, channel_value_satoshis)});
+               }
+               if channel_value_satoshis >= TOTAL_BITCOIN_SUPPLY_SATOSHIS {
+                       return Err(APIError::APIMisuseError{err: format!("funding_value must be smaller than the total bitcoin supply, it was {}", channel_value_satoshis)});
+               }
+               let channel_value_msat = channel_value_satoshis * 1000;
+               if push_msat > channel_value_msat {
+                       return Err(APIError::APIMisuseError { err: format!("Push value ({}) was larger than channel_value ({})", push_msat, channel_value_msat) });
+               }
+               if holder_selected_contest_delay < BREAKDOWN_TIMEOUT {
+                       return Err(APIError::APIMisuseError {err: format!("Configured with an unreasonable our_to_self_delay ({}) putting user funds at risks", holder_selected_contest_delay)});
+               }
+
+               let channel_type = get_initial_channel_type(&config, their_features);
+               debug_assert!(channel_type.is_subset(&channelmanager::provided_channel_type_features(&config)));
+
+               let (commitment_conf_target, anchor_outputs_value_msat)  = if channel_type.supports_anchors_zero_fee_htlc_tx() {
+                       (ConfirmationTarget::AnchorChannelFee, ANCHOR_OUTPUT_VALUE_SATOSHI * 2 * 1000)
+               } else {
+                       (ConfirmationTarget::NonAnchorChannelFee, 0)
+               };
+               let commitment_feerate = fee_estimator.bounded_sat_per_1000_weight(commitment_conf_target);
+
+               let value_to_self_msat = channel_value_satoshis * 1000 - push_msat;
+               let commitment_tx_fee = commit_tx_fee_msat(commitment_feerate, MIN_AFFORDABLE_HTLC_COUNT, &channel_type);
+               if value_to_self_msat.saturating_sub(anchor_outputs_value_msat) < commitment_tx_fee {
+                       return Err(APIError::APIMisuseError{ err: format!("Funding amount ({}) can't even pay fee for initial commitment transaction fee of {}.", value_to_self_msat / 1000, commitment_tx_fee / 1000) });
+               }
+
+               let mut secp_ctx = Secp256k1::new();
+               secp_ctx.seeded_randomize(&entropy_source.get_secure_random_bytes());
+
+               let shutdown_scriptpubkey = if config.channel_handshake_config.commit_upfront_shutdown_pubkey {
+                       match signer_provider.get_shutdown_scriptpubkey() {
+                               Ok(scriptpubkey) => Some(scriptpubkey),
+                               Err(_) => return Err(APIError::ChannelUnavailable { err: "Failed to get shutdown scriptpubkey".to_owned()}),
+                       }
+               } else { None };
+
+               if let Some(shutdown_scriptpubkey) = &shutdown_scriptpubkey {
+                       if !shutdown_scriptpubkey.is_compatible(&their_features) {
+                               return Err(APIError::IncompatibleShutdownScript { script: shutdown_scriptpubkey.clone() });
+                       }
+               }
+
+               let destination_script = match signer_provider.get_destination_script(channel_keys_id) {
+                       Ok(script) => script,
+                       Err(_) => return Err(APIError::ChannelUnavailable { err: "Failed to get destination script".to_owned()}),
+               };
+
+               let temporary_channel_id = temporary_channel_id.unwrap_or_else(|| ChannelId::temporary_from_entropy_source(entropy_source));
+
+               Ok(Self {
+                       user_id,
+
+                       config: LegacyChannelConfig {
+                               options: config.channel_config.clone(),
+                               announced_channel: config.channel_handshake_config.announced_channel,
+                               commit_upfront_shutdown_pubkey: config.channel_handshake_config.commit_upfront_shutdown_pubkey,
+                       },
+
+                       prev_config: None,
+
+                       inbound_handshake_limits_override: Some(config.channel_handshake_limits.clone()),
+
+                       channel_id: temporary_channel_id,
+                       temporary_channel_id: Some(temporary_channel_id),
+                       channel_state: ChannelState::NegotiatingFunding(NegotiatingFundingFlags::OUR_INIT_SENT),
+                       announcement_sigs_state: AnnouncementSigsState::NotSent,
+                       secp_ctx,
+                       // We'll add our counterparty's `funding_satoshis` when we receive `accept_channel2`.
+                       channel_value_satoshis,
+
+                       latest_monitor_update_id: 0,
+
+                       holder_signer: ChannelSignerType::Ecdsa(holder_signer),
+                       shutdown_scriptpubkey,
+                       destination_script,
+
+                       cur_holder_commitment_transaction_number: INITIAL_COMMITMENT_NUMBER,
+                       cur_counterparty_commitment_transaction_number: INITIAL_COMMITMENT_NUMBER,
+                       value_to_self_msat,
+
+                       pending_inbound_htlcs: Vec::new(),
+                       pending_outbound_htlcs: Vec::new(),
+                       holding_cell_htlc_updates: Vec::new(),
+                       pending_update_fee: None,
+                       holding_cell_update_fee: None,
+                       next_holder_htlc_id: 0,
+                       next_counterparty_htlc_id: 0,
+                       update_time_counter: 1,
+
+                       resend_order: RAACommitmentOrder::CommitmentFirst,
+
+                       monitor_pending_channel_ready: false,
+                       monitor_pending_revoke_and_ack: false,
+                       monitor_pending_commitment_signed: false,
+                       monitor_pending_forwards: Vec::new(),
+                       monitor_pending_failures: Vec::new(),
+                       monitor_pending_finalized_fulfills: Vec::new(),
+                       monitor_pending_update_adds: Vec::new(),
+
+                       signer_pending_commitment_update: false,
+                       signer_pending_funding: false,
+
+                       // We'll add our counterparty's `funding_satoshis` to these max commitment output assertions
+                       // when we receive `accept_channel2`.
+                       #[cfg(debug_assertions)]
+                       holder_max_commitment_tx_output: Mutex::new((channel_value_satoshis * 1000 - push_msat, push_msat)),
+                       #[cfg(debug_assertions)]
+                       counterparty_max_commitment_tx_output: Mutex::new((channel_value_satoshis * 1000 - push_msat, push_msat)),
+
+                       last_sent_closing_fee: None,
+                       pending_counterparty_closing_signed: None,
+                       expecting_peer_commitment_signed: false,
+                       closing_fee_limits: None,
+                       target_closing_feerate_sats_per_kw: None,
+
+                       funding_tx_confirmed_in: None,
+                       funding_tx_confirmation_height: 0,
+                       short_channel_id: None,
+                       channel_creation_height: current_chain_height,
+
+                       feerate_per_kw: commitment_feerate,
+                       counterparty_dust_limit_satoshis: 0,
+                       holder_dust_limit_satoshis: MIN_CHAN_DUST_LIMIT_SATOSHIS,
+                       counterparty_max_htlc_value_in_flight_msat: 0,
+                       // We'll adjust this to include our counterparty's `funding_satoshis` when we
+                       // receive `accept_channel2`.
+                       holder_max_htlc_value_in_flight_msat: get_holder_max_htlc_value_in_flight_msat(channel_value_satoshis, &config.channel_handshake_config),
+                       counterparty_selected_channel_reserve_satoshis: None, // Filled in in accept_channel
+                       holder_selected_channel_reserve_satoshis,
+                       counterparty_htlc_minimum_msat: 0,
+                       holder_htlc_minimum_msat: if config.channel_handshake_config.our_htlc_minimum_msat == 0 { 1 } else { config.channel_handshake_config.our_htlc_minimum_msat },
+                       counterparty_max_accepted_htlcs: 0,
+                       holder_max_accepted_htlcs: cmp::min(config.channel_handshake_config.our_max_accepted_htlcs, MAX_HTLCS),
+                       minimum_depth: None, // Filled in in accept_channel
+
+                       counterparty_forwarding_info: None,
+
+                       channel_transaction_parameters: ChannelTransactionParameters {
+                               holder_pubkeys: pubkeys,
+                               holder_selected_contest_delay: config.channel_handshake_config.our_to_self_delay,
+                               is_outbound_from_holder: true,
+                               counterparty_parameters: None,
+                               funding_outpoint: None,
+                               channel_type_features: channel_type.clone()
+                       },
+                       funding_transaction: None,
+                       is_batch_funding: None,
+
+                       counterparty_cur_commitment_point: None,
+                       counterparty_prev_commitment_point: None,
+                       counterparty_node_id,
+
+                       counterparty_shutdown_scriptpubkey: None,
+
+                       commitment_secrets: CounterpartyCommitmentSecrets::new(),
+
+                       channel_update_status: ChannelUpdateStatus::Enabled,
+                       closing_signed_in_flight: false,
+
+                       announcement_sigs: None,
+
+                       #[cfg(any(test, fuzzing))]
+                       next_local_commitment_tx_fee_info_cached: Mutex::new(None),
+                       #[cfg(any(test, fuzzing))]
+                       next_remote_commitment_tx_fee_info_cached: Mutex::new(None),
+
+                       workaround_lnd_bug_4006: None,
+                       sent_message_awaiting_response: None,
+
+                       latest_inbound_scid_alias: None,
+                       outbound_scid_alias,
+
+                       channel_pending_event_emitted: false,
+                       channel_ready_event_emitted: false,
+
+                       #[cfg(any(test, fuzzing))]
+                       historical_inbound_htlc_fulfills: new_hash_set(),
+
+                       channel_type,
+                       channel_keys_id,
+
+                       blocked_monitor_updates: Vec::new(),
+                       local_initiated_shutdown: None,
+               })
+       }
+
        /// Allowed in any state (including after shutdown)
        pub fn get_update_time_counter(&self) -> u32 {
                self.update_time_counter
@@ -2138,7 +2730,7 @@ impl<SP: Deref> ChannelContext<SP> where SP::Target: SignerProvider  {
                        feerate_per_kw = cmp::max(feerate_per_kw, feerate);
                }
                let feerate_plus_quarter = feerate_per_kw.checked_mul(1250).map(|v| v / 1000);
-               cmp::max(2530, feerate_plus_quarter.unwrap_or(u32::max_value()))
+               cmp::max(feerate_per_kw + 2530, feerate_plus_quarter.unwrap_or(u32::max_value()))
        }
 
        /// Get forwarding information for the counterparty.
@@ -2815,27 +3407,70 @@ impl<SP: Deref> ChannelContext<SP> where SP::Target: SignerProvider  {
                        _ => todo!()
                }
        }
-}
-
-// Internal utility functions for channels
 
-/// Returns the value to use for `holder_max_htlc_value_in_flight_msat` as a percentage of the
-/// `channel_value_satoshis` in msat, set through
-/// [`ChannelHandshakeConfig::max_inbound_htlc_value_in_flight_percent_of_channel`]
-///
-/// The effective percentage is lower bounded by 1% and upper bounded by 100%.
-///
-/// [`ChannelHandshakeConfig::max_inbound_htlc_value_in_flight_percent_of_channel`]: crate::util::config::ChannelHandshakeConfig::max_inbound_htlc_value_in_flight_percent_of_channel
-fn get_holder_max_htlc_value_in_flight_msat(channel_value_satoshis: u64, config: &ChannelHandshakeConfig) -> u64 {
-       let configured_percent = if config.max_inbound_htlc_value_in_flight_percent_of_channel < 1 {
-               1
-       } else if config.max_inbound_htlc_value_in_flight_percent_of_channel > 100 {
-               100
-       } else {
-               config.max_inbound_htlc_value_in_flight_percent_of_channel as u64
-       };
-       channel_value_satoshis * 10 * configured_percent
-}
+       /// If we receive an error message when attempting to open a channel, it may only be a rejection
+       /// of the channel type we tried, not of our ability to open any channel at all. We can see if a
+       /// downgrade of channel features would be possible so that we can still open the channel.
+       pub(crate) fn maybe_downgrade_channel_features<F: Deref>(
+               &mut self, fee_estimator: &LowerBoundedFeeEstimator<F>
+       ) -> Result<(), ()>
+       where
+               F::Target: FeeEstimator
+       {
+               if !self.is_outbound() ||
+                       !matches!(
+                               self.channel_state, ChannelState::NegotiatingFunding(flags)
+                               if flags == NegotiatingFundingFlags::OUR_INIT_SENT
+                       )
+               {
+                       return Err(());
+               }
+               if self.channel_type == ChannelTypeFeatures::only_static_remote_key() {
+                       // We've exhausted our options
+                       return Err(());
+               }
+               // We support opening a few different types of channels. Try removing our additional
+               // features one by one until we've either arrived at our default or the counterparty has
+               // accepted one.
+               //
+               // Due to the order below, we may not negotiate `option_anchors_zero_fee_htlc_tx` if the
+               // counterparty doesn't support `option_scid_privacy`. Since `get_initial_channel_type`
+               // checks whether the counterparty supports every feature, this would only happen if the
+               // counterparty is advertising the feature, but rejecting channels proposing the feature for
+               // whatever reason.
+               if self.channel_type.supports_anchors_zero_fee_htlc_tx() {
+                       self.channel_type.clear_anchors_zero_fee_htlc_tx();
+                       self.feerate_per_kw = fee_estimator.bounded_sat_per_1000_weight(ConfirmationTarget::NonAnchorChannelFee);
+                       assert!(!self.channel_transaction_parameters.channel_type_features.supports_anchors_nonzero_fee_htlc_tx());
+               } else if self.channel_type.supports_scid_privacy() {
+                       self.channel_type.clear_scid_privacy();
+               } else {
+                       self.channel_type = ChannelTypeFeatures::only_static_remote_key();
+               }
+               self.channel_transaction_parameters.channel_type_features = self.channel_type.clone();
+               Ok(())
+       }
+}
+
+// Internal utility functions for channels
+
+/// Returns the value to use for `holder_max_htlc_value_in_flight_msat` as a percentage of the
+/// `channel_value_satoshis` in msat, set through
+/// [`ChannelHandshakeConfig::max_inbound_htlc_value_in_flight_percent_of_channel`]
+///
+/// The effective percentage is lower bounded by 1% and upper bounded by 100%.
+///
+/// [`ChannelHandshakeConfig::max_inbound_htlc_value_in_flight_percent_of_channel`]: crate::util::config::ChannelHandshakeConfig::max_inbound_htlc_value_in_flight_percent_of_channel
+fn get_holder_max_htlc_value_in_flight_msat(channel_value_satoshis: u64, config: &ChannelHandshakeConfig) -> u64 {
+       let configured_percent = if config.max_inbound_htlc_value_in_flight_percent_of_channel < 1 {
+               1
+       } else if config.max_inbound_htlc_value_in_flight_percent_of_channel > 100 {
+               100
+       } else {
+               config.max_inbound_htlc_value_in_flight_percent_of_channel as u64
+       };
+       channel_value_satoshis * 10 * configured_percent
+}
 
 /// Returns a minimum channel reserve value the remote needs to maintain,
 /// required by us according to the configured or default
@@ -2859,6 +3494,20 @@ pub(crate) fn get_legacy_default_holder_selected_channel_reserve_satoshis(channe
        cmp::min(channel_value_satoshis, cmp::max(q, 1000))
 }
 
+/// Returns a minimum channel reserve value each party needs to maintain, fixed in the spec to a
+/// default of 1% of the total channel value.
+///
+/// Guaranteed to return a value no larger than channel_value_satoshis
+///
+/// This is used both for outbound and inbound channels and has lower bound
+/// of `dust_limit_satoshis`.
+#[cfg(dual_funding)]
+fn get_v2_channel_reserve_satoshis(channel_value_satoshis: u64, dust_limit_satoshis: u64) -> u64 {
+       // Fixed at 1% of channel value by spec.
+       let (q, _) = channel_value_satoshis.overflowing_div(100);
+       cmp::min(channel_value_satoshis, cmp::max(q, dust_limit_satoshis))
+}
+
 // Get the fee cost in SATS of a commitment tx with a given number of HTLC outputs.
 // Note that num_htlcs should not include dust HTLCs.
 #[inline]
@@ -2892,6 +3541,8 @@ pub(super) struct DualFundingChannelContext {
 // Counterparty designates channel data owned by the another channel participant entity.
 pub(super) struct Channel<SP: Deref> where SP::Target: SignerProvider {
        pub context: ChannelContext<SP>,
+       #[cfg(dual_funding)]
+       pub dual_funding_channel_context: Option<DualFundingChannelContext>,
 }
 
 #[cfg(any(test, fuzzing))]
@@ -3466,23 +4117,15 @@ impl<SP: Deref> Channel<SP> where
 
                log_info!(logger, "Received channel_ready from peer for channel {}", &self.context.channel_id());
 
-               Ok(self.get_announcement_sigs(node_signer, chain_hash, user_config, best_block.height(), logger))
+               Ok(self.get_announcement_sigs(node_signer, chain_hash, user_config, best_block.height, logger))
        }
 
-       pub fn update_add_htlc<F, FE: Deref, L: Deref>(
-               &mut self, msg: &msgs::UpdateAddHTLC, mut pending_forward_status: PendingHTLCStatus,
-               create_pending_htlc_status: F, fee_estimator: &LowerBoundedFeeEstimator<FE>, logger: &L
-       ) -> Result<(), ChannelError>
-       where F: for<'a> Fn(&'a Self, PendingHTLCStatus, u16) -> PendingHTLCStatus,
-               FE::Target: FeeEstimator, L::Target: Logger,
-       {
+       pub fn update_add_htlc(
+               &mut self, msg: &msgs::UpdateAddHTLC, pending_forward_status: PendingHTLCStatus,
+       ) -> Result<(), ChannelError> {
                if !matches!(self.context.channel_state, ChannelState::ChannelReady(_)) {
                        return Err(ChannelError::Close("Got add HTLC message when channel was not in an operational state".to_owned()));
                }
-               // We can't accept HTLCs sent after we've sent a shutdown.
-               if self.context.channel_state.is_local_shutdown_sent() {
-                       pending_forward_status = create_pending_htlc_status(self, pending_forward_status, 0x4000|8);
-               }
                // If the remote has sent a shutdown prior to adding this HTLC, then they are in violation of the spec.
                if self.context.channel_state.is_remote_shutdown_sent() {
                        return Err(ChannelError::Close("Got add HTLC message when channel was not in an operational state".to_owned()));
@@ -3501,7 +4144,6 @@ impl<SP: Deref> Channel<SP> where
                }
 
                let inbound_stats = self.context.get_inbound_pending_htlc_stats(None);
-               let outbound_stats = self.context.get_outbound_pending_htlc_stats(None);
                if inbound_stats.pending_htlcs + 1 > self.context.holder_max_accepted_htlcs as u32 {
                        return Err(ChannelError::Close(format!("Remote tried to push more than our max accepted HTLCs ({})", self.context.holder_max_accepted_htlcs)));
                }
@@ -3530,34 +4172,6 @@ impl<SP: Deref> Channel<SP> where
                        }
                }
 
-               let max_dust_htlc_exposure_msat = self.context.get_max_dust_htlc_exposure_msat(fee_estimator);
-               let (htlc_timeout_dust_limit, htlc_success_dust_limit) = if self.context.get_channel_type().supports_anchors_zero_fee_htlc_tx() {
-                       (0, 0)
-               } else {
-                       let dust_buffer_feerate = self.context.get_dust_buffer_feerate(None) as u64;
-                       (dust_buffer_feerate * htlc_timeout_tx_weight(self.context.get_channel_type()) / 1000,
-                               dust_buffer_feerate * htlc_success_tx_weight(self.context.get_channel_type()) / 1000)
-               };
-               let exposure_dust_limit_timeout_sats = htlc_timeout_dust_limit + self.context.counterparty_dust_limit_satoshis;
-               if msg.amount_msat / 1000 < exposure_dust_limit_timeout_sats {
-                       let on_counterparty_tx_dust_htlc_exposure_msat = inbound_stats.on_counterparty_tx_dust_exposure_msat + outbound_stats.on_counterparty_tx_dust_exposure_msat + msg.amount_msat;
-                       if on_counterparty_tx_dust_htlc_exposure_msat > max_dust_htlc_exposure_msat {
-                               log_info!(logger, "Cannot accept value that would put our exposure to dust HTLCs at {} over the limit {} on counterparty commitment tx",
-                                       on_counterparty_tx_dust_htlc_exposure_msat, max_dust_htlc_exposure_msat);
-                               pending_forward_status = create_pending_htlc_status(self, pending_forward_status, 0x1000|7);
-                       }
-               }
-
-               let exposure_dust_limit_success_sats = htlc_success_dust_limit + self.context.holder_dust_limit_satoshis;
-               if msg.amount_msat / 1000 < exposure_dust_limit_success_sats {
-                       let on_holder_tx_dust_htlc_exposure_msat = inbound_stats.on_holder_tx_dust_exposure_msat + outbound_stats.on_holder_tx_dust_exposure_msat + msg.amount_msat;
-                       if on_holder_tx_dust_htlc_exposure_msat > max_dust_htlc_exposure_msat {
-                               log_info!(logger, "Cannot accept value that would put our exposure to dust HTLCs at {} over the limit {} on holder commitment tx",
-                                       on_holder_tx_dust_htlc_exposure_msat, max_dust_htlc_exposure_msat);
-                               pending_forward_status = create_pending_htlc_status(self, pending_forward_status, 0x1000|7);
-                       }
-               }
-
                let pending_value_to_self_msat =
                        self.context.value_to_self_msat + inbound_stats.pending_htlcs_value_msat - removed_outbound_total_msat;
                let pending_remote_value_msat =
@@ -3591,23 +4205,7 @@ impl<SP: Deref> Channel<SP> where
                } else {
                        0
                };
-               if !self.context.is_outbound() {
-                       // `Some(())` is for the fee spike buffer we keep for the remote. This deviates from
-                       // the spec because the fee spike buffer requirement doesn't exist on the receiver's
-                       // side, only on the sender's. Note that with anchor outputs we are no longer as
-                       // sensitive to fee spikes, so we need to account for them.
-                       let htlc_candidate = HTLCCandidate::new(msg.amount_msat, HTLCInitiator::RemoteOffered);
-                       let mut remote_fee_cost_incl_stuck_buffer_msat = self.context.next_remote_commit_tx_fee_msat(htlc_candidate, Some(()));
-                       if !self.context.get_channel_type().supports_anchors_zero_fee_htlc_tx() {
-                               remote_fee_cost_incl_stuck_buffer_msat *= FEE_SPIKE_BUFFER_FEE_INCREASE_MULTIPLE;
-                       }
-                       if pending_remote_value_msat.saturating_sub(msg.amount_msat).saturating_sub(self.context.holder_selected_channel_reserve_satoshis * 1000).saturating_sub(anchor_outputs_value_msat) < remote_fee_cost_incl_stuck_buffer_msat {
-                               // Note that if the pending_forward_status is not updated here, then it's because we're already failing
-                               // the HTLC, i.e. its status is already set to failing.
-                               log_info!(logger, "Attempting to fail HTLC due to fee spike buffer violation in channel {}. Rebalancing is required.", &self.context.channel_id());
-                               pending_forward_status = create_pending_htlc_status(self, pending_forward_status, 0x1000|7);
-                       }
-               } else {
+               if self.context.is_outbound() {
                        // Check that they won't violate our local required channel reserve by adding this HTLC.
                        let htlc_candidate = HTLCCandidate::new(msg.amount_msat, HTLCInitiator::RemoteOffered);
                        let local_commit_tx_fee_msat = self.context.next_local_commit_tx_fee_msat(htlc_candidate, None);
@@ -3635,7 +4233,9 @@ impl<SP: Deref> Channel<SP> where
                        amount_msat: msg.amount_msat,
                        payment_hash: msg.payment_hash,
                        cltv_expiry: msg.cltv_expiry,
-                       state: InboundHTLCState::RemoteAnnounced(pending_forward_status),
+                       state: InboundHTLCState::RemoteAnnounced(InboundHTLCResolution::Resolved {
+                               pending_htlc_status: pending_forward_status
+                       }),
                });
                Ok(())
        }
@@ -3841,13 +4441,13 @@ impl<SP: Deref> Channel<SP> where
                }
 
                for htlc in self.context.pending_inbound_htlcs.iter_mut() {
-                       let new_forward = if let &InboundHTLCState::RemoteAnnounced(ref forward_info) = &htlc.state {
-                               Some(forward_info.clone())
+                       let htlc_resolution = if let &InboundHTLCState::RemoteAnnounced(ref resolution) = &htlc.state {
+                               Some(resolution.clone())
                        } else { None };
-                       if let Some(forward_info) = new_forward {
+                       if let Some(htlc_resolution) = htlc_resolution {
                                log_trace!(logger, "Updating HTLC {} to AwaitingRemoteRevokeToAnnounce due to commitment_signed in channel {}.",
                                        &htlc.payment_hash, &self.context.channel_id);
-                               htlc.state = InboundHTLCState::AwaitingRemoteRevokeToAnnounce(forward_info);
+                               htlc.state = InboundHTLCState::AwaitingRemoteRevokeToAnnounce(htlc_resolution);
                                need_commitment = true;
                        }
                }
@@ -4157,6 +4757,7 @@ impl<SP: Deref> Channel<SP> where
 
                log_trace!(logger, "Updating HTLCs on receipt of RAA in channel {}...", &self.context.channel_id());
                let mut to_forward_infos = Vec::new();
+               let mut pending_update_adds = Vec::new();
                let mut revoked_htlcs = Vec::new();
                let mut finalized_claimed_htlcs = Vec::new();
                let mut update_fail_htlcs = Vec::new();
@@ -4204,29 +4805,37 @@ impl<SP: Deref> Channel<SP> where
                                        let mut state = InboundHTLCState::Committed;
                                        mem::swap(&mut state, &mut htlc.state);
 
-                                       if let InboundHTLCState::AwaitingRemoteRevokeToAnnounce(forward_info) = state {
+                                       if let InboundHTLCState::AwaitingRemoteRevokeToAnnounce(resolution) = state {
                                                log_trace!(logger, " ...promoting inbound AwaitingRemoteRevokeToAnnounce {} to AwaitingAnnouncedRemoteRevoke", &htlc.payment_hash);
-                                               htlc.state = InboundHTLCState::AwaitingAnnouncedRemoteRevoke(forward_info);
+                                               htlc.state = InboundHTLCState::AwaitingAnnouncedRemoteRevoke(resolution);
                                                require_commitment = true;
-                                       } else if let InboundHTLCState::AwaitingAnnouncedRemoteRevoke(forward_info) = state {
-                                               match forward_info {
-                                                       PendingHTLCStatus::Fail(fail_msg) => {
-                                                               log_trace!(logger, " ...promoting inbound AwaitingAnnouncedRemoteRevoke {} to LocalRemoved due to PendingHTLCStatus indicating failure", &htlc.payment_hash);
-                                                               require_commitment = true;
-                                                               match fail_msg {
-                                                                       HTLCFailureMsg::Relay(msg) => {
-                                                                               htlc.state = InboundHTLCState::LocalRemoved(InboundHTLCRemovalReason::FailRelay(msg.reason.clone()));
-                                                                               update_fail_htlcs.push(msg)
-                                                                       },
-                                                                       HTLCFailureMsg::Malformed(msg) => {
-                                                                               htlc.state = InboundHTLCState::LocalRemoved(InboundHTLCRemovalReason::FailMalformed((msg.sha256_of_onion, msg.failure_code)));
-                                                                               update_fail_malformed_htlcs.push(msg)
+                                       } else if let InboundHTLCState::AwaitingAnnouncedRemoteRevoke(resolution) = state {
+                                               match resolution {
+                                                       InboundHTLCResolution::Resolved { pending_htlc_status } =>
+                                                               match pending_htlc_status {
+                                                                       PendingHTLCStatus::Fail(fail_msg) => {
+                                                                               log_trace!(logger, " ...promoting inbound AwaitingAnnouncedRemoteRevoke {} to LocalRemoved due to PendingHTLCStatus indicating failure", &htlc.payment_hash);
+                                                                               require_commitment = true;
+                                                                               match fail_msg {
+                                                                                       HTLCFailureMsg::Relay(msg) => {
+                                                                                               htlc.state = InboundHTLCState::LocalRemoved(InboundHTLCRemovalReason::FailRelay(msg.reason.clone()));
+                                                                                               update_fail_htlcs.push(msg)
+                                                                                       },
+                                                                                       HTLCFailureMsg::Malformed(msg) => {
+                                                                                               htlc.state = InboundHTLCState::LocalRemoved(InboundHTLCRemovalReason::FailMalformed((msg.sha256_of_onion, msg.failure_code)));
+                                                                                               update_fail_malformed_htlcs.push(msg)
+                                                                                       },
+                                                                               }
                                                                        },
+                                                                       PendingHTLCStatus::Forward(forward_info) => {
+                                                                               log_trace!(logger, " ...promoting inbound AwaitingAnnouncedRemoteRevoke {} to Committed, attempting to forward", &htlc.payment_hash);
+                                                                               to_forward_infos.push((forward_info, htlc.htlc_id));
+                                                                               htlc.state = InboundHTLCState::Committed;
+                                                                       }
                                                                }
-                                                       },
-                                                       PendingHTLCStatus::Forward(forward_info) => {
+                                                       InboundHTLCResolution::Pending { update_add_htlc } => {
                                                                log_trace!(logger, " ...promoting inbound AwaitingAnnouncedRemoteRevoke {} to Committed", &htlc.payment_hash);
-                                                               to_forward_infos.push((forward_info, htlc.htlc_id));
+                                                               pending_update_adds.push(update_add_htlc);
                                                                htlc.state = InboundHTLCState::Committed;
                                                        }
                                                }
@@ -4287,6 +4896,8 @@ impl<SP: Deref> Channel<SP> where
                        }
                }
 
+               self.context.monitor_pending_update_adds.append(&mut pending_update_adds);
+
                if self.context.channel_state.is_monitor_update_in_progress() {
                        // We can't actually generate a new commitment transaction (incl by freeing holding
                        // cells) while we can't update the monitor, so we just return what we have.
@@ -4587,13 +5198,16 @@ impl<SP: Deref> Channel<SP> where
                mem::swap(&mut failed_htlcs, &mut self.context.monitor_pending_failures);
                let mut finalized_claimed_htlcs = Vec::new();
                mem::swap(&mut finalized_claimed_htlcs, &mut self.context.monitor_pending_finalized_fulfills);
+               let mut pending_update_adds = Vec::new();
+               mem::swap(&mut pending_update_adds, &mut self.context.monitor_pending_update_adds);
 
                if self.context.channel_state.is_peer_disconnected() {
                        self.context.monitor_pending_revoke_and_ack = false;
                        self.context.monitor_pending_commitment_signed = false;
                        return MonitorRestoreUpdates {
                                raa: None, commitment_update: None, order: RAACommitmentOrder::RevokeAndACKFirst,
-                               accepted_htlcs, failed_htlcs, finalized_claimed_htlcs, funding_broadcastable, channel_ready, announcement_sigs
+                               accepted_htlcs, failed_htlcs, finalized_claimed_htlcs, pending_update_adds,
+                               funding_broadcastable, channel_ready, announcement_sigs
                        };
                }
 
@@ -4615,7 +5229,8 @@ impl<SP: Deref> Channel<SP> where
                        if commitment_update.is_some() { "a" } else { "no" }, if raa.is_some() { "an" } else { "no" },
                        match order { RAACommitmentOrder::CommitmentFirst => "commitment", RAACommitmentOrder::RevokeAndACKFirst => "RAA"});
                MonitorRestoreUpdates {
-                       raa, commitment_update, order, accepted_htlcs, failed_htlcs, finalized_claimed_htlcs, funding_broadcastable, channel_ready, announcement_sigs
+                       raa, commitment_update, order, accepted_htlcs, failed_htlcs, finalized_claimed_htlcs,
+                       pending_update_adds, funding_broadcastable, channel_ready, announcement_sigs
                }
        }
 
@@ -4855,7 +5470,7 @@ impl<SP: Deref> Channel<SP> where
 
                let shutdown_msg = self.get_outbound_shutdown();
 
-               let announcement_sigs = self.get_announcement_sigs(node_signer, chain_hash, user_config, best_block.height(), logger);
+               let announcement_sigs = self.get_announcement_sigs(node_signer, chain_hash, user_config, best_block.height, logger);
 
                if matches!(self.context.channel_state, ChannelState::AwaitingChannelReady(_)) {
                        // If we're waiting on a monitor update, we shouldn't re-send any channel_ready's.
@@ -5479,6 +6094,86 @@ impl<SP: Deref> Channel<SP> where
                        })
        }
 
+       pub fn can_accept_incoming_htlc<F: Deref, L: Deref>(
+               &self, msg: &msgs::UpdateAddHTLC, fee_estimator: &LowerBoundedFeeEstimator<F>, logger: L
+       ) -> Result<(), (&'static str, u16)>
+       where
+               F::Target: FeeEstimator,
+               L::Target: Logger
+       {
+               if self.context.channel_state.is_local_shutdown_sent() {
+                       return Err(("Shutdown was already sent", 0x4000|8))
+               }
+
+               let inbound_stats = self.context.get_inbound_pending_htlc_stats(None);
+               let outbound_stats = self.context.get_outbound_pending_htlc_stats(None);
+               let max_dust_htlc_exposure_msat = self.context.get_max_dust_htlc_exposure_msat(fee_estimator);
+               let (htlc_timeout_dust_limit, htlc_success_dust_limit) = if self.context.get_channel_type().supports_anchors_zero_fee_htlc_tx() {
+                       (0, 0)
+               } else {
+                       let dust_buffer_feerate = self.context.get_dust_buffer_feerate(None) as u64;
+                       (dust_buffer_feerate * htlc_timeout_tx_weight(self.context.get_channel_type()) / 1000,
+                               dust_buffer_feerate * htlc_success_tx_weight(self.context.get_channel_type()) / 1000)
+               };
+               let exposure_dust_limit_timeout_sats = htlc_timeout_dust_limit + self.context.counterparty_dust_limit_satoshis;
+               if msg.amount_msat / 1000 < exposure_dust_limit_timeout_sats {
+                       let on_counterparty_tx_dust_htlc_exposure_msat = inbound_stats.on_counterparty_tx_dust_exposure_msat + outbound_stats.on_counterparty_tx_dust_exposure_msat + msg.amount_msat;
+                       if on_counterparty_tx_dust_htlc_exposure_msat > max_dust_htlc_exposure_msat {
+                               log_info!(logger, "Cannot accept value that would put our exposure to dust HTLCs at {} over the limit {} on counterparty commitment tx",
+                                       on_counterparty_tx_dust_htlc_exposure_msat, max_dust_htlc_exposure_msat);
+                               return Err(("Exceeded our dust exposure limit on counterparty commitment tx", 0x1000|7))
+                       }
+               }
+
+               let exposure_dust_limit_success_sats = htlc_success_dust_limit + self.context.holder_dust_limit_satoshis;
+               if msg.amount_msat / 1000 < exposure_dust_limit_success_sats {
+                       let on_holder_tx_dust_htlc_exposure_msat = inbound_stats.on_holder_tx_dust_exposure_msat + outbound_stats.on_holder_tx_dust_exposure_msat + msg.amount_msat;
+                       if on_holder_tx_dust_htlc_exposure_msat > max_dust_htlc_exposure_msat {
+                               log_info!(logger, "Cannot accept value that would put our exposure to dust HTLCs at {} over the limit {} on holder commitment tx",
+                                       on_holder_tx_dust_htlc_exposure_msat, max_dust_htlc_exposure_msat);
+                               return Err(("Exceeded our dust exposure limit on holder commitment tx", 0x1000|7))
+                       }
+               }
+
+               let anchor_outputs_value_msat = if self.context.get_channel_type().supports_anchors_zero_fee_htlc_tx() {
+                       ANCHOR_OUTPUT_VALUE_SATOSHI * 2 * 1000
+               } else {
+                       0
+               };
+
+               let mut removed_outbound_total_msat = 0;
+               for ref htlc in self.context.pending_outbound_htlcs.iter() {
+                       if let OutboundHTLCState::AwaitingRemoteRevokeToRemove(OutboundHTLCOutcome::Success(_)) = htlc.state {
+                               removed_outbound_total_msat += htlc.amount_msat;
+                       } else if let OutboundHTLCState::AwaitingRemovedRemoteRevoke(OutboundHTLCOutcome::Success(_)) = htlc.state {
+                               removed_outbound_total_msat += htlc.amount_msat;
+                       }
+               }
+
+               let pending_value_to_self_msat =
+                       self.context.value_to_self_msat + inbound_stats.pending_htlcs_value_msat - removed_outbound_total_msat;
+               let pending_remote_value_msat =
+                       self.context.channel_value_satoshis * 1000 - pending_value_to_self_msat;
+
+               if !self.context.is_outbound() {
+                       // `Some(())` is for the fee spike buffer we keep for the remote. This deviates from
+                       // the spec because the fee spike buffer requirement doesn't exist on the receiver's
+                       // side, only on the sender's. Note that with anchor outputs we are no longer as
+                       // sensitive to fee spikes, so we need to account for them.
+                       let htlc_candidate = HTLCCandidate::new(msg.amount_msat, HTLCInitiator::RemoteOffered);
+                       let mut remote_fee_cost_incl_stuck_buffer_msat = self.context.next_remote_commit_tx_fee_msat(htlc_candidate, Some(()));
+                       if !self.context.get_channel_type().supports_anchors_zero_fee_htlc_tx() {
+                               remote_fee_cost_incl_stuck_buffer_msat *= FEE_SPIKE_BUFFER_FEE_INCREASE_MULTIPLE;
+                       }
+                       if pending_remote_value_msat.saturating_sub(msg.amount_msat).saturating_sub(self.context.holder_selected_channel_reserve_satoshis * 1000).saturating_sub(anchor_outputs_value_msat) < remote_fee_cost_incl_stuck_buffer_msat {
+                               log_info!(logger, "Attempting to fail HTLC due to fee spike buffer violation in channel {}. Rebalancing is required.", &self.context.channel_id());
+                               return Err(("Fee spike buffer violation", 0x1000|7));
+                       }
+               }
+
+               Ok(())
+       }
+
        pub fn get_cur_holder_commitment_transaction_number(&self) -> u64 {
                self.context.cur_holder_commitment_transaction_number + 1
        }
@@ -6601,222 +7296,60 @@ impl<SP: Deref> OutboundV1Channel<SP> where SP::Target: SignerProvider {
        where ES::Target: EntropySource,
              F::Target: FeeEstimator
        {
-               let holder_selected_contest_delay = config.channel_handshake_config.our_to_self_delay;
-               let channel_keys_id = signer_provider.generate_channel_keys_id(false, channel_value_satoshis, user_id);
-               let holder_signer = signer_provider.derive_channel_signer(channel_value_satoshis, channel_keys_id);
-               let pubkeys = holder_signer.pubkeys().clone();
-
-               if !their_features.supports_wumbo() && channel_value_satoshis > MAX_FUNDING_SATOSHIS_NO_WUMBO {
-                       return Err(APIError::APIMisuseError{err: format!("funding_value must not exceed {}, it was {}", MAX_FUNDING_SATOSHIS_NO_WUMBO, channel_value_satoshis)});
-               }
-               if channel_value_satoshis >= TOTAL_BITCOIN_SUPPLY_SATOSHIS {
-                       return Err(APIError::APIMisuseError{err: format!("funding_value must be smaller than the total bitcoin supply, it was {}", channel_value_satoshis)});
-               }
-               let channel_value_msat = channel_value_satoshis * 1000;
-               if push_msat > channel_value_msat {
-                       return Err(APIError::APIMisuseError { err: format!("Push value ({}) was larger than channel_value ({})", push_msat, channel_value_msat) });
-               }
-               if holder_selected_contest_delay < BREAKDOWN_TIMEOUT {
-                       return Err(APIError::APIMisuseError {err: format!("Configured with an unreasonable our_to_self_delay ({}) putting user funds at risks", holder_selected_contest_delay)});
-               }
                let holder_selected_channel_reserve_satoshis = get_holder_selected_channel_reserve_satoshis(channel_value_satoshis, config);
                if holder_selected_channel_reserve_satoshis < MIN_CHAN_DUST_LIMIT_SATOSHIS {
                        // Protocol level safety check in place, although it should never happen because
                        // of `MIN_THEIR_CHAN_RESERVE_SATOSHIS`
-                       return Err(APIError::APIMisuseError { err: format!("Holder selected channel  reserve below implemention limit dust_limit_satoshis {}", holder_selected_channel_reserve_satoshis) });
+                       return Err(APIError::APIMisuseError { err: format!("Holder selected channel reserve below \
+                               implemention limit dust_limit_satoshis {}", holder_selected_channel_reserve_satoshis) });
                }
 
-               let channel_type = Self::get_initial_channel_type(&config, their_features);
-               debug_assert!(channel_type.is_subset(&channelmanager::provided_channel_type_features(&config)));
+               let channel_keys_id = signer_provider.generate_channel_keys_id(false, channel_value_satoshis, user_id);
+               let holder_signer = signer_provider.derive_channel_signer(channel_value_satoshis, channel_keys_id);
+               let pubkeys = holder_signer.pubkeys().clone();
 
-               let (commitment_conf_target, anchor_outputs_value_msat)  = if channel_type.supports_anchors_zero_fee_htlc_tx() {
-                       (ConfirmationTarget::AnchorChannelFee, ANCHOR_OUTPUT_VALUE_SATOSHI * 2 * 1000)
-               } else {
-                       (ConfirmationTarget::NonAnchorChannelFee, 0)
+               let chan = Self {
+                       context: ChannelContext::new_for_outbound_channel(
+                               fee_estimator,
+                               entropy_source,
+                               signer_provider,
+                               counterparty_node_id,
+                               their_features,
+                               channel_value_satoshis,
+                               push_msat,
+                               user_id,
+                               config,
+                               current_chain_height,
+                               outbound_scid_alias,
+                               temporary_channel_id,
+                               holder_selected_channel_reserve_satoshis,
+                               channel_keys_id,
+                               holder_signer,
+                               pubkeys,
+                       )?,
+                       unfunded_context: UnfundedChannelContext { unfunded_channel_age_ticks: 0 }
                };
-               let commitment_feerate = fee_estimator.bounded_sat_per_1000_weight(commitment_conf_target);
-
-               let value_to_self_msat = channel_value_satoshis * 1000 - push_msat;
-               let commitment_tx_fee = commit_tx_fee_msat(commitment_feerate, MIN_AFFORDABLE_HTLC_COUNT, &channel_type);
-               if value_to_self_msat.saturating_sub(anchor_outputs_value_msat) < commitment_tx_fee {
-                       return Err(APIError::APIMisuseError{ err: format!("Funding amount ({}) can't even pay fee for initial commitment transaction fee of {}.", value_to_self_msat / 1000, commitment_tx_fee / 1000) });
-               }
-
-               let mut secp_ctx = Secp256k1::new();
-               secp_ctx.seeded_randomize(&entropy_source.get_secure_random_bytes());
+               Ok(chan)
+       }
 
-               let shutdown_scriptpubkey = if config.channel_handshake_config.commit_upfront_shutdown_pubkey {
-                       match signer_provider.get_shutdown_scriptpubkey() {
-                               Ok(scriptpubkey) => Some(scriptpubkey),
-                               Err(_) => return Err(APIError::ChannelUnavailable { err: "Failed to get shutdown scriptpubkey".to_owned()}),
-                       }
-               } else { None };
+       /// Only allowed after [`ChannelContext::channel_transaction_parameters`] is set.
+       fn get_funding_created_msg<L: Deref>(&mut self, logger: &L) -> Option<msgs::FundingCreated> where L::Target: Logger {
+               let counterparty_keys = self.context.build_remote_transaction_keys();
+               let counterparty_initial_commitment_tx = self.context.build_commitment_transaction(self.context.cur_counterparty_commitment_transaction_number, &counterparty_keys, false, false, logger).tx;
+               let signature = match &self.context.holder_signer {
+                       // TODO (taproot|arik): move match into calling method for Taproot
+                       ChannelSignerType::Ecdsa(ecdsa) => {
+                               ecdsa.sign_counterparty_commitment(&counterparty_initial_commitment_tx, Vec::new(), Vec::new(), &self.context.secp_ctx)
+                                       .map(|(sig, _)| sig).ok()?
+                       },
+                       // TODO (taproot|arik)
+                       #[cfg(taproot)]
+                       _ => todo!()
+               };
 
-               if let Some(shutdown_scriptpubkey) = &shutdown_scriptpubkey {
-                       if !shutdown_scriptpubkey.is_compatible(&their_features) {
-                               return Err(APIError::IncompatibleShutdownScript { script: shutdown_scriptpubkey.clone() });
-                       }
-               }
-
-               let destination_script = match signer_provider.get_destination_script(channel_keys_id) {
-                       Ok(script) => script,
-                       Err(_) => return Err(APIError::ChannelUnavailable { err: "Failed to get destination script".to_owned()}),
-               };
-
-               let temporary_channel_id = temporary_channel_id.unwrap_or_else(|| ChannelId::temporary_from_entropy_source(entropy_source));
-
-               Ok(Self {
-                       context: ChannelContext {
-                               user_id,
-
-                               config: LegacyChannelConfig {
-                                       options: config.channel_config.clone(),
-                                       announced_channel: config.channel_handshake_config.announced_channel,
-                                       commit_upfront_shutdown_pubkey: config.channel_handshake_config.commit_upfront_shutdown_pubkey,
-                               },
-
-                               prev_config: None,
-
-                               inbound_handshake_limits_override: Some(config.channel_handshake_limits.clone()),
-
-                               channel_id: temporary_channel_id,
-                               temporary_channel_id: Some(temporary_channel_id),
-                               channel_state: ChannelState::NegotiatingFunding(NegotiatingFundingFlags::OUR_INIT_SENT),
-                               announcement_sigs_state: AnnouncementSigsState::NotSent,
-                               secp_ctx,
-                               channel_value_satoshis,
-
-                               latest_monitor_update_id: 0,
-
-                               holder_signer: ChannelSignerType::Ecdsa(holder_signer),
-                               shutdown_scriptpubkey,
-                               destination_script,
-
-                               cur_holder_commitment_transaction_number: INITIAL_COMMITMENT_NUMBER,
-                               cur_counterparty_commitment_transaction_number: INITIAL_COMMITMENT_NUMBER,
-                               value_to_self_msat,
-
-                               pending_inbound_htlcs: Vec::new(),
-                               pending_outbound_htlcs: Vec::new(),
-                               holding_cell_htlc_updates: Vec::new(),
-                               pending_update_fee: None,
-                               holding_cell_update_fee: None,
-                               next_holder_htlc_id: 0,
-                               next_counterparty_htlc_id: 0,
-                               update_time_counter: 1,
-
-                               resend_order: RAACommitmentOrder::CommitmentFirst,
-
-                               monitor_pending_channel_ready: false,
-                               monitor_pending_revoke_and_ack: false,
-                               monitor_pending_commitment_signed: false,
-                               monitor_pending_forwards: Vec::new(),
-                               monitor_pending_failures: Vec::new(),
-                               monitor_pending_finalized_fulfills: Vec::new(),
-
-                               signer_pending_commitment_update: false,
-                               signer_pending_funding: false,
-
-                               #[cfg(debug_assertions)]
-                               holder_max_commitment_tx_output: Mutex::new((channel_value_satoshis * 1000 - push_msat, push_msat)),
-                               #[cfg(debug_assertions)]
-                               counterparty_max_commitment_tx_output: Mutex::new((channel_value_satoshis * 1000 - push_msat, push_msat)),
-
-                               last_sent_closing_fee: None,
-                               pending_counterparty_closing_signed: None,
-                               expecting_peer_commitment_signed: false,
-                               closing_fee_limits: None,
-                               target_closing_feerate_sats_per_kw: None,
-
-                               funding_tx_confirmed_in: None,
-                               funding_tx_confirmation_height: 0,
-                               short_channel_id: None,
-                               channel_creation_height: current_chain_height,
-
-                               feerate_per_kw: commitment_feerate,
-                               counterparty_dust_limit_satoshis: 0,
-                               holder_dust_limit_satoshis: MIN_CHAN_DUST_LIMIT_SATOSHIS,
-                               counterparty_max_htlc_value_in_flight_msat: 0,
-                               holder_max_htlc_value_in_flight_msat: get_holder_max_htlc_value_in_flight_msat(channel_value_satoshis, &config.channel_handshake_config),
-                               counterparty_selected_channel_reserve_satoshis: None, // Filled in in accept_channel
-                               holder_selected_channel_reserve_satoshis,
-                               counterparty_htlc_minimum_msat: 0,
-                               holder_htlc_minimum_msat: if config.channel_handshake_config.our_htlc_minimum_msat == 0 { 1 } else { config.channel_handshake_config.our_htlc_minimum_msat },
-                               counterparty_max_accepted_htlcs: 0,
-                               holder_max_accepted_htlcs: cmp::min(config.channel_handshake_config.our_max_accepted_htlcs, MAX_HTLCS),
-                               minimum_depth: None, // Filled in in accept_channel
-
-                               counterparty_forwarding_info: None,
-
-                               channel_transaction_parameters: ChannelTransactionParameters {
-                                       holder_pubkeys: pubkeys,
-                                       holder_selected_contest_delay: config.channel_handshake_config.our_to_self_delay,
-                                       is_outbound_from_holder: true,
-                                       counterparty_parameters: None,
-                                       funding_outpoint: None,
-                                       channel_type_features: channel_type.clone()
-                               },
-                               funding_transaction: None,
-                               is_batch_funding: None,
-
-                               counterparty_cur_commitment_point: None,
-                               counterparty_prev_commitment_point: None,
-                               counterparty_node_id,
-
-                               counterparty_shutdown_scriptpubkey: None,
-
-                               commitment_secrets: CounterpartyCommitmentSecrets::new(),
-
-                               channel_update_status: ChannelUpdateStatus::Enabled,
-                               closing_signed_in_flight: false,
-
-                               announcement_sigs: None,
-
-                               #[cfg(any(test, fuzzing))]
-                               next_local_commitment_tx_fee_info_cached: Mutex::new(None),
-                               #[cfg(any(test, fuzzing))]
-                               next_remote_commitment_tx_fee_info_cached: Mutex::new(None),
-
-                               workaround_lnd_bug_4006: None,
-                               sent_message_awaiting_response: None,
-
-                               latest_inbound_scid_alias: None,
-                               outbound_scid_alias,
-
-                               channel_pending_event_emitted: false,
-                               channel_ready_event_emitted: false,
-
-                               #[cfg(any(test, fuzzing))]
-                               historical_inbound_htlc_fulfills: new_hash_set(),
-
-                               channel_type,
-                               channel_keys_id,
-
-                               blocked_monitor_updates: Vec::new(),
-                               local_initiated_shutdown: None,
-                       },
-                       unfunded_context: UnfundedChannelContext { unfunded_channel_age_ticks: 0 }
-               })
-       }
-
-       /// Only allowed after [`ChannelContext::channel_transaction_parameters`] is set.
-       fn get_funding_created_msg<L: Deref>(&mut self, logger: &L) -> Option<msgs::FundingCreated> where L::Target: Logger {
-               let counterparty_keys = self.context.build_remote_transaction_keys();
-               let counterparty_initial_commitment_tx = self.context.build_commitment_transaction(self.context.cur_counterparty_commitment_transaction_number, &counterparty_keys, false, false, logger).tx;
-               let signature = match &self.context.holder_signer {
-                       // TODO (taproot|arik): move match into calling method for Taproot
-                       ChannelSignerType::Ecdsa(ecdsa) => {
-                               ecdsa.sign_counterparty_commitment(&counterparty_initial_commitment_tx, Vec::new(), Vec::new(), &self.context.secp_ctx)
-                                       .map(|(sig, _)| sig).ok()?
-                       },
-                       // TODO (taproot|arik)
-                       #[cfg(taproot)]
-                       _ => todo!()
-               };
-
-               if self.context.signer_pending_funding {
-                       log_trace!(logger, "Counterparty commitment signature ready for funding_created message: clearing signer_pending_funding");
-                       self.context.signer_pending_funding = false;
+               if self.context.signer_pending_funding {
+                       log_trace!(logger, "Counterparty commitment signature ready for funding_created message: clearing signer_pending_funding");
+                       self.context.signer_pending_funding = false;
                }
 
                Some(msgs::FundingCreated {
@@ -6890,29 +7423,6 @@ impl<SP: Deref> OutboundV1Channel<SP> where SP::Target: SignerProvider {
                Ok(funding_created)
        }
 
-       fn get_initial_channel_type(config: &UserConfig, their_features: &InitFeatures) -> ChannelTypeFeatures {
-               // The default channel type (ie the first one we try) depends on whether the channel is
-               // public - if it is, we just go with `only_static_remotekey` as it's the only option
-               // available. If it's private, we first try `scid_privacy` as it provides better privacy
-               // with no other changes, and fall back to `only_static_remotekey`.
-               let mut ret = ChannelTypeFeatures::only_static_remote_key();
-               if !config.channel_handshake_config.announced_channel &&
-                       config.channel_handshake_config.negotiate_scid_privacy &&
-                       their_features.supports_scid_privacy() {
-                       ret.set_scid_privacy_required();
-               }
-
-               // Optionally, if the user would like to negotiate the `anchors_zero_fee_htlc_tx` option, we
-               // set it now. If they don't understand it, we'll fall back to our default of
-               // `only_static_remotekey`.
-               if config.channel_handshake_config.negotiate_anchors_zero_fee_htlc_tx &&
-                       their_features.supports_anchors_zero_fee_htlc_tx() {
-                       ret.set_anchors_zero_fee_htlc_tx_required();
-               }
-
-               ret
-       }
-
        /// If we receive an error message, it may only be a rejection of the channel type we tried,
        /// not of our ability to open any channel at all. Thus, on error, we should first call this
        /// and see if we get a new `OpenChannel` message, otherwise the channel is failed.
@@ -6922,37 +7432,7 @@ impl<SP: Deref> OutboundV1Channel<SP> where SP::Target: SignerProvider {
        where
                F::Target: FeeEstimator
        {
-               if !self.context.is_outbound() ||
-                       !matches!(
-                               self.context.channel_state, ChannelState::NegotiatingFunding(flags)
-                               if flags == NegotiatingFundingFlags::OUR_INIT_SENT
-                       )
-               {
-                       return Err(());
-               }
-               if self.context.channel_type == ChannelTypeFeatures::only_static_remote_key() {
-                       // We've exhausted our options
-                       return Err(());
-               }
-               // We support opening a few different types of channels. Try removing our additional
-               // features one by one until we've either arrived at our default or the counterparty has
-               // accepted one.
-               //
-               // Due to the order below, we may not negotiate `option_anchors_zero_fee_htlc_tx` if the
-               // counterparty doesn't support `option_scid_privacy`. Since `get_initial_channel_type`
-               // checks whether the counterparty supports every feature, this would only happen if the
-               // counterparty is advertising the feature, but rejecting channels proposing the feature for
-               // whatever reason.
-               if self.context.channel_type.supports_anchors_zero_fee_htlc_tx() {
-                       self.context.channel_type.clear_anchors_zero_fee_htlc_tx();
-                       self.context.feerate_per_kw = fee_estimator.bounded_sat_per_1000_weight(ConfirmationTarget::NonAnchorChannelFee);
-                       assert!(!self.context.channel_transaction_parameters.channel_type_features.supports_anchors_nonzero_fee_htlc_tx());
-               } else if self.context.channel_type.supports_scid_privacy() {
-                       self.context.channel_type.clear_scid_privacy();
-               } else {
-                       self.context.channel_type = ChannelTypeFeatures::only_static_remote_key();
-               }
-               self.context.channel_transaction_parameters.channel_type_features = self.context.channel_type.clone();
+               self.context.maybe_downgrade_channel_features(fee_estimator)?;
                Ok(self.get_open_channel(chain_hash))
        }
 
@@ -7222,7 +7702,11 @@ impl<SP: Deref> OutboundV1Channel<SP> where SP::Target: SignerProvider {
 
                log_info!(logger, "Received funding_signed from peer for channel {}", &self.context.channel_id());
 
-               let mut channel = Channel { context: self.context };
+               let mut channel = Channel {
+                       context: self.context,
+                       #[cfg(dual_funding)]
+                       dual_funding_channel_context: None,
+               };
 
                let need_channel_ready = channel.check_get_channel_ready(0).is_some();
                channel.monitor_updating_paused(false, false, need_channel_ready, Vec::new(), Vec::new(), Vec::new());
@@ -7247,12 +7731,12 @@ pub(super) struct InboundV1Channel<SP: Deref> where SP::Target: SignerProvider {
 }
 
 /// Fetches the [`ChannelTypeFeatures`] that will be used for a channel built from a given
-/// [`msgs::OpenChannel`].
+/// [`msgs::CommonOpenChannelFields`].
 pub(super) fn channel_type_from_open_channel(
-       msg: &msgs::OpenChannel, their_features: &InitFeatures,
+       common_fields: &msgs::CommonOpenChannelFields, their_features: &InitFeatures,
        our_supported_features: &ChannelTypeFeatures
 ) -> Result<ChannelTypeFeatures, ChannelError> {
-       if let Some(channel_type) = &msg.common_fields.channel_type {
+       if let Some(channel_type) = &common_fields.channel_type {
                if channel_type.supports_any_optional_bits() {
                        return Err(ChannelError::Close("Channel Type field contained optional bits - this is not allowed".to_owned()));
                }
@@ -7267,7 +7751,7 @@ pub(super) fn channel_type_from_open_channel(
                if !channel_type.is_subset(our_supported_features) {
                        return Err(ChannelError::Close("Channel Type contains unsupported features".to_owned()));
                }
-               let announced_channel = if (msg.common_fields.channel_flags & 1) == 1 { true } else { false };
+               let announced_channel = if (common_fields.channel_flags & 1) == 1 { true } else { false };
                if channel_type.requires_scid_privacy() && announced_channel {
                        return Err(ChannelError::Close("SCID Alias/Privacy Channel Type cannot be set on a public channel".to_owned()));
                }
@@ -7295,15 +7779,12 @@ impl<SP: Deref> InboundV1Channel<SP> where SP::Target: SignerProvider {
                          L::Target: Logger,
        {
                let logger = WithContext::from(logger, Some(counterparty_node_id), Some(msg.common_fields.temporary_channel_id));
-               let announced_channel = if (msg.common_fields.channel_flags & 1) == 1 { true } else { false };
 
                // First check the channel type is known, failing before we do anything else if we don't
                // support this channel type.
-               let channel_type = channel_type_from_open_channel(msg, their_features, our_supported_features)?;
+               let channel_type = channel_type_from_open_channel(&msg.common_fields, their_features, our_supported_features)?;
 
-               let channel_keys_id = signer_provider.generate_channel_keys_id(true, msg.common_fields.funding_satoshis, user_id);
-               let holder_signer = signer_provider.derive_channel_signer(msg.common_fields.funding_satoshis, channel_keys_id);
-               let pubkeys = holder_signer.pubkeys().clone();
+               let holder_selected_channel_reserve_satoshis = get_holder_selected_channel_reserve_satoshis(msg.common_fields.funding_satoshis, config);
                let counterparty_pubkeys = ChannelPublicKeys {
                        funding_pubkey: msg.common_fields.funding_pubkey,
                        revocation_basepoint: RevocationBasepoint::from(msg.common_fields.revocation_basepoint),
@@ -7312,297 +7793,29 @@ impl<SP: Deref> InboundV1Channel<SP> where SP::Target: SignerProvider {
                        htlc_basepoint: HtlcBasepoint::from(msg.common_fields.htlc_basepoint)
                };
 
-               if config.channel_handshake_config.our_to_self_delay < BREAKDOWN_TIMEOUT {
-                       return Err(ChannelError::Close(format!("Configured with an unreasonable our_to_self_delay ({}) putting user funds at risks. It must be greater than {}", config.channel_handshake_config.our_to_self_delay, BREAKDOWN_TIMEOUT)));
-               }
-
-               // Check sanity of message fields:
-               if msg.common_fields.funding_satoshis > config.channel_handshake_limits.max_funding_satoshis {
-                       return Err(ChannelError::Close(format!("Per our config, funding must be at most {}. It was {}", config.channel_handshake_limits.max_funding_satoshis, msg.common_fields.funding_satoshis)));
-               }
-               if msg.common_fields.funding_satoshis >= TOTAL_BITCOIN_SUPPLY_SATOSHIS {
-                       return Err(ChannelError::Close(format!("Funding must be smaller than the total bitcoin supply. It was {}", msg.common_fields.funding_satoshis)));
-               }
-               if msg.channel_reserve_satoshis > msg.common_fields.funding_satoshis {
-                       return Err(ChannelError::Close(format!("Bogus channel_reserve_satoshis ({}). Must be not greater than funding_satoshis: {}", msg.channel_reserve_satoshis, msg.common_fields.funding_satoshis)));
-               }
-               let full_channel_value_msat = (msg.common_fields.funding_satoshis - msg.channel_reserve_satoshis) * 1000;
-               if msg.push_msat > full_channel_value_msat {
-                       return Err(ChannelError::Close(format!("push_msat {} was larger than channel amount minus reserve ({})", msg.push_msat, full_channel_value_msat)));
-               }
-               if msg.common_fields.dust_limit_satoshis > msg.common_fields.funding_satoshis {
-                       return Err(ChannelError::Close(format!("dust_limit_satoshis {} was larger than funding_satoshis {}. Peer never wants payout outputs?", msg.common_fields.dust_limit_satoshis, msg.common_fields.funding_satoshis)));
-               }
-               if msg.common_fields.htlc_minimum_msat >= full_channel_value_msat {
-                       return Err(ChannelError::Close(format!("Minimum htlc value ({}) was larger than full channel value ({})", msg.common_fields.htlc_minimum_msat, full_channel_value_msat)));
-               }
-               Channel::<SP>::check_remote_fee(&channel_type, fee_estimator, msg.common_fields.commitment_feerate_sat_per_1000_weight, None, &&logger)?;
-
-               let max_counterparty_selected_contest_delay = u16::min(config.channel_handshake_limits.their_to_self_delay, MAX_LOCAL_BREAKDOWN_TIMEOUT);
-               if msg.common_fields.to_self_delay > max_counterparty_selected_contest_delay {
-                       return Err(ChannelError::Close(format!("They wanted our payments to be delayed by a needlessly long period. Upper limit: {}. Actual: {}", max_counterparty_selected_contest_delay, msg.common_fields.to_self_delay)));
-               }
-               if msg.common_fields.max_accepted_htlcs < 1 {
-                       return Err(ChannelError::Close("0 max_accepted_htlcs makes for a useless channel".to_owned()));
-               }
-               if msg.common_fields.max_accepted_htlcs > MAX_HTLCS {
-                       return Err(ChannelError::Close(format!("max_accepted_htlcs was {}. It must not be larger than {}", msg.common_fields.max_accepted_htlcs, MAX_HTLCS)));
-               }
-
-               // Now check against optional parameters as set by config...
-               if msg.common_fields.funding_satoshis < config.channel_handshake_limits.min_funding_satoshis {
-                       return Err(ChannelError::Close(format!("Funding satoshis ({}) is less than the user specified limit ({})", msg.common_fields.funding_satoshis, config.channel_handshake_limits.min_funding_satoshis)));
-               }
-               if msg.common_fields.htlc_minimum_msat > config.channel_handshake_limits.max_htlc_minimum_msat {
-                       return Err(ChannelError::Close(format!("htlc_minimum_msat ({}) is higher than the user specified limit ({})", msg.common_fields.htlc_minimum_msat,  config.channel_handshake_limits.max_htlc_minimum_msat)));
-               }
-               if msg.common_fields.max_htlc_value_in_flight_msat < config.channel_handshake_limits.min_max_htlc_value_in_flight_msat {
-                       return Err(ChannelError::Close(format!("max_htlc_value_in_flight_msat ({}) is less than the user specified limit ({})", msg.common_fields.max_htlc_value_in_flight_msat, config.channel_handshake_limits.min_max_htlc_value_in_flight_msat)));
-               }
-               if msg.channel_reserve_satoshis > config.channel_handshake_limits.max_channel_reserve_satoshis {
-                       return Err(ChannelError::Close(format!("channel_reserve_satoshis ({}) is higher than the user specified limit ({})", msg.channel_reserve_satoshis, config.channel_handshake_limits.max_channel_reserve_satoshis)));
-               }
-               if msg.common_fields.max_accepted_htlcs < config.channel_handshake_limits.min_max_accepted_htlcs {
-                       return Err(ChannelError::Close(format!("max_accepted_htlcs ({}) is less than the user specified limit ({})", msg.common_fields.max_accepted_htlcs, config.channel_handshake_limits.min_max_accepted_htlcs)));
-               }
-               if msg.common_fields.dust_limit_satoshis < MIN_CHAN_DUST_LIMIT_SATOSHIS {
-                       return Err(ChannelError::Close(format!("dust_limit_satoshis ({}) is less than the implementation limit ({})", msg.common_fields.dust_limit_satoshis, MIN_CHAN_DUST_LIMIT_SATOSHIS)));
-               }
-               if msg.common_fields.dust_limit_satoshis >  MAX_CHAN_DUST_LIMIT_SATOSHIS {
-                       return Err(ChannelError::Close(format!("dust_limit_satoshis ({}) is greater than the implementation limit ({})", msg.common_fields.dust_limit_satoshis, MAX_CHAN_DUST_LIMIT_SATOSHIS)));
-               }
-
-               // Convert things into internal flags and prep our state:
-
-               if config.channel_handshake_limits.force_announced_channel_preference {
-                       if config.channel_handshake_config.announced_channel != announced_channel {
-                               return Err(ChannelError::Close("Peer tried to open channel but their announcement preference is different from ours".to_owned()));
-                       }
-               }
-
-               let holder_selected_channel_reserve_satoshis = get_holder_selected_channel_reserve_satoshis(msg.common_fields.funding_satoshis, config);
-               if holder_selected_channel_reserve_satoshis < MIN_CHAN_DUST_LIMIT_SATOSHIS {
-                       // Protocol level safety check in place, although it should never happen because
-                       // of `MIN_THEIR_CHAN_RESERVE_SATOSHIS`
-                       return Err(ChannelError::Close(format!("Suitable channel reserve not found. remote_channel_reserve was ({}). dust_limit_satoshis is ({}).", holder_selected_channel_reserve_satoshis, MIN_CHAN_DUST_LIMIT_SATOSHIS)));
-               }
-               if holder_selected_channel_reserve_satoshis * 1000 >= full_channel_value_msat {
-                       return Err(ChannelError::Close(format!("Suitable channel reserve not found. remote_channel_reserve was ({})msats. Channel value is ({} - {})msats.", holder_selected_channel_reserve_satoshis * 1000, full_channel_value_msat, msg.push_msat)));
-               }
-               if msg.channel_reserve_satoshis < MIN_CHAN_DUST_LIMIT_SATOSHIS {
-                       log_debug!(logger, "channel_reserve_satoshis ({}) is smaller than our dust limit ({}). We can broadcast stale states without any risk, implying this channel is very insecure for our counterparty.",
-                               msg.channel_reserve_satoshis, MIN_CHAN_DUST_LIMIT_SATOSHIS);
-               }
-               if holder_selected_channel_reserve_satoshis < msg.common_fields.dust_limit_satoshis {
-                       return Err(ChannelError::Close(format!("Dust limit ({}) too high for the channel reserve we require the remote to keep ({})", msg.common_fields.dust_limit_satoshis, holder_selected_channel_reserve_satoshis)));
-               }
-
-               // check if the funder's amount for the initial commitment tx is sufficient
-               // for full fee payment plus a few HTLCs to ensure the channel will be useful.
-               let anchor_outputs_value = if channel_type.supports_anchors_zero_fee_htlc_tx() {
-                       ANCHOR_OUTPUT_VALUE_SATOSHI * 2
-               } else {
-                       0
-               };
-               let funders_amount_msat = msg.common_fields.funding_satoshis * 1000 - msg.push_msat;
-               let commitment_tx_fee = commit_tx_fee_msat(msg.common_fields.commitment_feerate_sat_per_1000_weight, MIN_AFFORDABLE_HTLC_COUNT, &channel_type) / 1000;
-               if (funders_amount_msat / 1000).saturating_sub(anchor_outputs_value) < commitment_tx_fee {
-                       return Err(ChannelError::Close(format!("Funding amount ({} sats) can't even pay fee for initial commitment transaction fee of {} sats.", (funders_amount_msat / 1000).saturating_sub(anchor_outputs_value), commitment_tx_fee)));
-               }
-
-               let to_remote_satoshis = funders_amount_msat / 1000 - commitment_tx_fee - anchor_outputs_value;
-               // While it's reasonable for us to not meet the channel reserve initially (if they don't
-               // want to push much to us), our counterparty should always have more than our reserve.
-               if to_remote_satoshis < holder_selected_channel_reserve_satoshis {
-                       return Err(ChannelError::Close("Insufficient funding amount for initial reserve".to_owned()));
-               }
-
-               let counterparty_shutdown_scriptpubkey = if their_features.supports_upfront_shutdown_script() {
-                       match &msg.common_fields.shutdown_scriptpubkey {
-                               &Some(ref script) => {
-                                       // Peer is signaling upfront_shutdown and has opt-out with a 0-length script. We don't enforce anything
-                                       if script.len() == 0 {
-                                               None
-                                       } else {
-                                               if !script::is_bolt2_compliant(&script, their_features) {
-                                                       return Err(ChannelError::Close(format!("Peer is signaling upfront_shutdown but has provided an unacceptable scriptpubkey format: {}", script)))
-                                               }
-                                               Some(script.clone())
-                                       }
-                               },
-                               // Peer is signaling upfront shutdown but don't opt-out with correct mechanism (a.k.a 0-length script). Peer looks buggy, we fail the channel
-                               &None => {
-                                       return Err(ChannelError::Close("Peer is signaling upfront_shutdown but we don't get any script. Use 0-length script to opt-out".to_owned()));
-                               }
-                       }
-               } else { None };
-
-               let shutdown_scriptpubkey = if config.channel_handshake_config.commit_upfront_shutdown_pubkey {
-                       match signer_provider.get_shutdown_scriptpubkey() {
-                               Ok(scriptpubkey) => Some(scriptpubkey),
-                               Err(_) => return Err(ChannelError::Close("Failed to get upfront shutdown scriptpubkey".to_owned())),
-                       }
-               } else { None };
-
-               if let Some(shutdown_scriptpubkey) = &shutdown_scriptpubkey {
-                       if !shutdown_scriptpubkey.is_compatible(&their_features) {
-                               return Err(ChannelError::Close(format!("Provided a scriptpubkey format not accepted by peer: {}", shutdown_scriptpubkey)));
-                       }
-               }
-
-               let destination_script = match signer_provider.get_destination_script(channel_keys_id) {
-                       Ok(script) => script,
-                       Err(_) => return Err(ChannelError::Close("Failed to get destination script".to_owned())),
-               };
-
-               let mut secp_ctx = Secp256k1::new();
-               secp_ctx.seeded_randomize(&entropy_source.get_secure_random_bytes());
-
-               let minimum_depth = if is_0conf {
-                       Some(0)
-               } else {
-                       Some(cmp::max(config.channel_handshake_config.minimum_depth, 1))
-               };
-
                let chan = Self {
-                       context: ChannelContext {
-                               user_id,
-
-                               config: LegacyChannelConfig {
-                                       options: config.channel_config.clone(),
-                                       announced_channel,
-                                       commit_upfront_shutdown_pubkey: config.channel_handshake_config.commit_upfront_shutdown_pubkey,
-                               },
-
-                               prev_config: None,
-
-                               inbound_handshake_limits_override: None,
-
-                               temporary_channel_id: Some(msg.common_fields.temporary_channel_id),
-                               channel_id: msg.common_fields.temporary_channel_id,
-                               channel_state: ChannelState::NegotiatingFunding(
-                                       NegotiatingFundingFlags::OUR_INIT_SENT | NegotiatingFundingFlags::THEIR_INIT_SENT
-                               ),
-                               announcement_sigs_state: AnnouncementSigsState::NotSent,
-                               secp_ctx,
-
-                               latest_monitor_update_id: 0,
-
-                               holder_signer: ChannelSignerType::Ecdsa(holder_signer),
-                               shutdown_scriptpubkey,
-                               destination_script,
-
-                               cur_holder_commitment_transaction_number: INITIAL_COMMITMENT_NUMBER,
-                               cur_counterparty_commitment_transaction_number: INITIAL_COMMITMENT_NUMBER,
-                               value_to_self_msat: msg.push_msat,
-
-                               pending_inbound_htlcs: Vec::new(),
-                               pending_outbound_htlcs: Vec::new(),
-                               holding_cell_htlc_updates: Vec::new(),
-                               pending_update_fee: None,
-                               holding_cell_update_fee: None,
-                               next_holder_htlc_id: 0,
-                               next_counterparty_htlc_id: 0,
-                               update_time_counter: 1,
-
-                               resend_order: RAACommitmentOrder::CommitmentFirst,
-
-                               monitor_pending_channel_ready: false,
-                               monitor_pending_revoke_and_ack: false,
-                               monitor_pending_commitment_signed: false,
-                               monitor_pending_forwards: Vec::new(),
-                               monitor_pending_failures: Vec::new(),
-                               monitor_pending_finalized_fulfills: Vec::new(),
-
-                               signer_pending_commitment_update: false,
-                               signer_pending_funding: false,
-
-                               #[cfg(debug_assertions)]
-                               holder_max_commitment_tx_output: Mutex::new((msg.push_msat, msg.common_fields.funding_satoshis * 1000 - msg.push_msat)),
-                               #[cfg(debug_assertions)]
-                               counterparty_max_commitment_tx_output: Mutex::new((msg.push_msat, msg.common_fields.funding_satoshis * 1000 - msg.push_msat)),
-
-                               last_sent_closing_fee: None,
-                               pending_counterparty_closing_signed: None,
-                               expecting_peer_commitment_signed: false,
-                               closing_fee_limits: None,
-                               target_closing_feerate_sats_per_kw: None,
-
-                               funding_tx_confirmed_in: None,
-                               funding_tx_confirmation_height: 0,
-                               short_channel_id: None,
-                               channel_creation_height: current_chain_height,
-
-                               feerate_per_kw: msg.common_fields.commitment_feerate_sat_per_1000_weight,
-                               channel_value_satoshis: msg.common_fields.funding_satoshis,
-                               counterparty_dust_limit_satoshis: msg.common_fields.dust_limit_satoshis,
-                               holder_dust_limit_satoshis: MIN_CHAN_DUST_LIMIT_SATOSHIS,
-                               counterparty_max_htlc_value_in_flight_msat: cmp::min(msg.common_fields.max_htlc_value_in_flight_msat, msg.common_fields.funding_satoshis * 1000),
-                               holder_max_htlc_value_in_flight_msat: get_holder_max_htlc_value_in_flight_msat(msg.common_fields.funding_satoshis, &config.channel_handshake_config),
-                               counterparty_selected_channel_reserve_satoshis: Some(msg.channel_reserve_satoshis),
-                               holder_selected_channel_reserve_satoshis,
-                               counterparty_htlc_minimum_msat: msg.common_fields.htlc_minimum_msat,
-                               holder_htlc_minimum_msat: if config.channel_handshake_config.our_htlc_minimum_msat == 0 { 1 } else { config.channel_handshake_config.our_htlc_minimum_msat },
-                               counterparty_max_accepted_htlcs: msg.common_fields.max_accepted_htlcs,
-                               holder_max_accepted_htlcs: cmp::min(config.channel_handshake_config.our_max_accepted_htlcs, MAX_HTLCS),
-                               minimum_depth,
-
-                               counterparty_forwarding_info: None,
-
-                               channel_transaction_parameters: ChannelTransactionParameters {
-                                       holder_pubkeys: pubkeys,
-                                       holder_selected_contest_delay: config.channel_handshake_config.our_to_self_delay,
-                                       is_outbound_from_holder: false,
-                                       counterparty_parameters: Some(CounterpartyChannelTransactionParameters {
-                                               selected_contest_delay: msg.common_fields.to_self_delay,
-                                               pubkeys: counterparty_pubkeys,
-                                       }),
-                                       funding_outpoint: None,
-                                       channel_type_features: channel_type.clone()
-                               },
-                               funding_transaction: None,
-                               is_batch_funding: None,
-
-                               counterparty_cur_commitment_point: Some(msg.common_fields.first_per_commitment_point),
-                               counterparty_prev_commitment_point: None,
+                       context: ChannelContext::new_for_inbound_channel(
+                               fee_estimator,
+                               entropy_source,
+                               signer_provider,
                                counterparty_node_id,
+                               their_features,
+                               user_id,
+                               config,
+                               current_chain_height,
+                               &&logger,
+                               is_0conf,
+                               0,
 
-                               counterparty_shutdown_scriptpubkey,
-
-                               commitment_secrets: CounterpartyCommitmentSecrets::new(),
-
-                               channel_update_status: ChannelUpdateStatus::Enabled,
-                               closing_signed_in_flight: false,
-
-                               announcement_sigs: None,
-
-                               #[cfg(any(test, fuzzing))]
-                               next_local_commitment_tx_fee_info_cached: Mutex::new(None),
-                               #[cfg(any(test, fuzzing))]
-                               next_remote_commitment_tx_fee_info_cached: Mutex::new(None),
-
-                               workaround_lnd_bug_4006: None,
-                               sent_message_awaiting_response: None,
-
-                               latest_inbound_scid_alias: None,
-                               outbound_scid_alias: 0,
-
-                               channel_pending_event_emitted: false,
-                               channel_ready_event_emitted: false,
-
-                               #[cfg(any(test, fuzzing))]
-                               historical_inbound_htlc_fulfills: new_hash_set(),
-
+                               counterparty_pubkeys,
                                channel_type,
-                               channel_keys_id,
-
-                               local_initiated_shutdown: None,
-
-                               blocked_monitor_updates: Vec::new(),
-                       },
+                               holder_selected_channel_reserve_satoshis,
+                               msg.channel_reserve_satoshis,
+                               msg.push_msat,
+                               msg.common_fields.clone(),
+                       )?,
                        unfunded_context: UnfundedChannelContext { unfunded_channel_age_ticks: 0 }
                };
-
                Ok(chan)
        }
 
@@ -7781,6 +7994,8 @@ impl<SP: Deref> InboundV1Channel<SP> where SP::Target: SignerProvider {
                // `ChannelMonitor`.
                let mut channel = Channel {
                        context: self.context,
+                       #[cfg(dual_funding)]
+                       dual_funding_channel_context: None,
                };
                let need_channel_ready = channel.check_get_channel_ready(0).is_some();
                channel.monitor_updating_paused(false, false, need_channel_ready, Vec::new(), Vec::new(), Vec::new());
@@ -7789,7 +8004,310 @@ impl<SP: Deref> InboundV1Channel<SP> where SP::Target: SignerProvider {
        }
 }
 
-const SERIALIZATION_VERSION: u8 = 3;
+// A not-yet-funded outbound (from holder) channel using V2 channel establishment.
+#[cfg(dual_funding)]
+pub(super) struct OutboundV2Channel<SP: Deref> where SP::Target: SignerProvider {
+       pub context: ChannelContext<SP>,
+       pub unfunded_context: UnfundedChannelContext,
+       #[cfg(dual_funding)]
+       pub dual_funding_context: DualFundingChannelContext,
+}
+
+#[cfg(dual_funding)]
+impl<SP: Deref> OutboundV2Channel<SP> where SP::Target: SignerProvider {
+       pub fn new<ES: Deref, F: Deref>(
+               fee_estimator: &LowerBoundedFeeEstimator<F>, entropy_source: &ES, signer_provider: &SP,
+               counterparty_node_id: PublicKey, their_features: &InitFeatures, funding_satoshis: u64,
+               user_id: u128, config: &UserConfig, current_chain_height: u32, outbound_scid_alias: u64,
+               funding_confirmation_target: ConfirmationTarget,
+       ) -> Result<OutboundV2Channel<SP>, APIError>
+       where ES::Target: EntropySource,
+             F::Target: FeeEstimator,
+       {
+               let channel_keys_id = signer_provider.generate_channel_keys_id(false, funding_satoshis, user_id);
+               let holder_signer = signer_provider.derive_channel_signer(funding_satoshis, channel_keys_id);
+               let pubkeys = holder_signer.pubkeys().clone();
+
+               let temporary_channel_id = Some(ChannelId::temporary_v2_from_revocation_basepoint(&pubkeys.revocation_basepoint));
+
+               let holder_selected_channel_reserve_satoshis = get_v2_channel_reserve_satoshis(
+                       funding_satoshis, MIN_CHAN_DUST_LIMIT_SATOSHIS);
+
+               let funding_feerate_sat_per_1000_weight = fee_estimator.bounded_sat_per_1000_weight(funding_confirmation_target);
+               let funding_tx_locktime = current_chain_height;
+
+               let chan = Self {
+                       context: ChannelContext::new_for_outbound_channel(
+                               fee_estimator,
+                               entropy_source,
+                               signer_provider,
+                               counterparty_node_id,
+                               their_features,
+                               funding_satoshis,
+                               0,
+                               user_id,
+                               config,
+                               current_chain_height,
+                               outbound_scid_alias,
+                               temporary_channel_id,
+                               holder_selected_channel_reserve_satoshis,
+                               channel_keys_id,
+                               holder_signer,
+                               pubkeys,
+                       )?,
+                       unfunded_context: UnfundedChannelContext { unfunded_channel_age_ticks: 0 },
+                       dual_funding_context: DualFundingChannelContext {
+                               our_funding_satoshis: funding_satoshis,
+                               their_funding_satoshis: 0,
+                               funding_tx_locktime,
+                               funding_feerate_sat_per_1000_weight,
+                       }
+               };
+               Ok(chan)
+       }
+
+       /// If we receive an error message, it may only be a rejection of the channel type we tried,
+       /// not of our ability to open any channel at all. Thus, on error, we should first call this
+       /// and see if we get a new `OpenChannelV2` message, otherwise the channel is failed.
+       pub(crate) fn maybe_handle_error_without_close<F: Deref>(
+               &mut self, chain_hash: ChainHash, fee_estimator: &LowerBoundedFeeEstimator<F>
+       ) -> Result<msgs::OpenChannelV2, ()>
+       where
+               F::Target: FeeEstimator
+       {
+               self.context.maybe_downgrade_channel_features(fee_estimator)?;
+               Ok(self.get_open_channel_v2(chain_hash))
+       }
+
+       pub fn get_open_channel_v2(&self, chain_hash: ChainHash) -> msgs::OpenChannelV2 {
+               if self.context.have_received_message() {
+                       debug_assert!(false, "Cannot generate an open_channel2 after we've moved forward");
+               }
+
+               if self.context.cur_holder_commitment_transaction_number != INITIAL_COMMITMENT_NUMBER {
+                       debug_assert!(false, "Tried to send an open_channel2 for a channel that has already advanced");
+               }
+
+               let first_per_commitment_point = self.context.holder_signer.as_ref()
+                       .get_per_commitment_point(self.context.cur_holder_commitment_transaction_number,
+                               &self.context.secp_ctx);
+               let second_per_commitment_point = self.context.holder_signer.as_ref()
+                       .get_per_commitment_point(self.context.cur_holder_commitment_transaction_number - 1,
+                               &self.context.secp_ctx);
+               let keys = self.context.get_holder_pubkeys();
+
+               msgs::OpenChannelV2 {
+                       common_fields: msgs::CommonOpenChannelFields {
+                               chain_hash,
+                               temporary_channel_id: self.context.temporary_channel_id.unwrap(),
+                               funding_satoshis: self.context.channel_value_satoshis,
+                               dust_limit_satoshis: self.context.holder_dust_limit_satoshis,
+                               max_htlc_value_in_flight_msat: self.context.holder_max_htlc_value_in_flight_msat,
+                               htlc_minimum_msat: self.context.holder_htlc_minimum_msat,
+                               commitment_feerate_sat_per_1000_weight: self.context.feerate_per_kw,
+                               to_self_delay: self.context.get_holder_selected_contest_delay(),
+                               max_accepted_htlcs: self.context.holder_max_accepted_htlcs,
+                               funding_pubkey: keys.funding_pubkey,
+                               revocation_basepoint: keys.revocation_basepoint.to_public_key(),
+                               payment_basepoint: keys.payment_point,
+                               delayed_payment_basepoint: keys.delayed_payment_basepoint.to_public_key(),
+                               htlc_basepoint: keys.htlc_basepoint.to_public_key(),
+                               first_per_commitment_point,
+                               channel_flags: if self.context.config.announced_channel {1} else {0},
+                               shutdown_scriptpubkey: Some(match &self.context.shutdown_scriptpubkey {
+                                       Some(script) => script.clone().into_inner(),
+                                       None => Builder::new().into_script(),
+                               }),
+                               channel_type: Some(self.context.channel_type.clone()),
+                       },
+                       funding_feerate_sat_per_1000_weight: self.context.feerate_per_kw,
+                       second_per_commitment_point,
+                       locktime: self.dual_funding_context.funding_tx_locktime,
+                       require_confirmed_inputs: None,
+               }
+       }
+}
+
+// A not-yet-funded inbound (from counterparty) channel using V2 channel establishment.
+#[cfg(dual_funding)]
+pub(super) struct InboundV2Channel<SP: Deref> where SP::Target: SignerProvider {
+       pub context: ChannelContext<SP>,
+       pub unfunded_context: UnfundedChannelContext,
+       pub dual_funding_context: DualFundingChannelContext,
+}
+
+#[cfg(dual_funding)]
+impl<SP: Deref> InboundV2Channel<SP> where SP::Target: SignerProvider {
+       /// Creates a new dual-funded channel from a remote side's request for one.
+       /// Assumes chain_hash has already been checked and corresponds with what we expect!
+       pub fn new<ES: Deref, F: Deref, L: Deref>(
+               fee_estimator: &LowerBoundedFeeEstimator<F>, entropy_source: &ES, signer_provider: &SP,
+               counterparty_node_id: PublicKey, our_supported_features: &ChannelTypeFeatures,
+               their_features: &InitFeatures, msg: &msgs::OpenChannelV2, funding_satoshis: u64, user_id: u128,
+               config: &UserConfig, current_chain_height: u32, logger: &L,
+       ) -> Result<InboundV2Channel<SP>, ChannelError>
+               where ES::Target: EntropySource,
+                         F::Target: FeeEstimator,
+                         L::Target: Logger,
+       {
+               let channel_value_satoshis = funding_satoshis.saturating_add(msg.common_fields.funding_satoshis);
+               let counterparty_selected_channel_reserve_satoshis = get_v2_channel_reserve_satoshis(
+                       channel_value_satoshis, msg.common_fields.dust_limit_satoshis);
+               let holder_selected_channel_reserve_satoshis = get_v2_channel_reserve_satoshis(
+                       channel_value_satoshis, MIN_CHAN_DUST_LIMIT_SATOSHIS);
+
+               // First check the channel type is known, failing before we do anything else if we don't
+               // support this channel type.
+               if msg.common_fields.channel_type.is_none() {
+                       return Err(ChannelError::Close(format!("Rejecting V2 channel {} missing channel_type",
+                               msg.common_fields.temporary_channel_id)))
+               }
+               let channel_type = channel_type_from_open_channel(&msg.common_fields, their_features, our_supported_features)?;
+
+               let counterparty_pubkeys = ChannelPublicKeys {
+                       funding_pubkey: msg.common_fields.funding_pubkey,
+                       revocation_basepoint: RevocationBasepoint(msg.common_fields.revocation_basepoint),
+                       payment_point: msg.common_fields.payment_basepoint,
+                       delayed_payment_basepoint: DelayedPaymentBasepoint(msg.common_fields.delayed_payment_basepoint),
+                       htlc_basepoint: HtlcBasepoint(msg.common_fields.htlc_basepoint)
+               };
+
+               let mut context = ChannelContext::new_for_inbound_channel(
+                       fee_estimator,
+                       entropy_source,
+                       signer_provider,
+                       counterparty_node_id,
+                       their_features,
+                       user_id,
+                       config,
+                       current_chain_height,
+                       logger,
+                       false,
+
+                       funding_satoshis,
+
+                       counterparty_pubkeys,
+                       channel_type,
+                       holder_selected_channel_reserve_satoshis,
+                       counterparty_selected_channel_reserve_satoshis,
+                       0 /* push_msat not used in dual-funding */,
+                       msg.common_fields.clone(),
+               )?;
+               let channel_id = ChannelId::v2_from_revocation_basepoints(
+                       &context.get_holder_pubkeys().revocation_basepoint,
+                       &context.get_counterparty_pubkeys().revocation_basepoint);
+               context.channel_id = channel_id;
+
+               let chan = Self {
+                       context,
+                       unfunded_context: UnfundedChannelContext { unfunded_channel_age_ticks: 0 },
+                       dual_funding_context: DualFundingChannelContext {
+                               our_funding_satoshis: funding_satoshis,
+                               their_funding_satoshis: msg.common_fields.funding_satoshis,
+                               funding_tx_locktime: msg.locktime,
+                               funding_feerate_sat_per_1000_weight: msg.funding_feerate_sat_per_1000_weight,
+                       }
+               };
+
+               Ok(chan)
+       }
+
+       /// Marks an inbound channel as accepted and generates a [`msgs::AcceptChannelV2`] message which
+       /// should be sent back to the counterparty node.
+       ///
+       /// [`msgs::AcceptChannelV2`]: crate::ln::msgs::AcceptChannelV2
+       pub fn accept_inbound_dual_funded_channel(&mut self) -> msgs::AcceptChannelV2 {
+               if self.context.is_outbound() {
+                       debug_assert!(false, "Tried to send accept_channel for an outbound channel?");
+               }
+               if !matches!(
+                       self.context.channel_state, ChannelState::NegotiatingFunding(flags)
+                       if flags == (NegotiatingFundingFlags::OUR_INIT_SENT | NegotiatingFundingFlags::THEIR_INIT_SENT)
+               ) {
+                       debug_assert!(false, "Tried to send accept_channel2 after channel had moved forward");
+               }
+               if self.context.cur_holder_commitment_transaction_number != INITIAL_COMMITMENT_NUMBER {
+                       debug_assert!(false, "Tried to send an accept_channel2 for a channel that has already advanced");
+               }
+
+               self.generate_accept_channel_v2_message()
+       }
+
+       /// This function is used to explicitly generate a [`msgs::AcceptChannel`] message for an
+       /// inbound channel. If the intention is to accept an inbound channel, use
+       /// [`InboundV1Channel::accept_inbound_channel`] instead.
+       ///
+       /// [`msgs::AcceptChannelV2`]: crate::ln::msgs::AcceptChannelV2
+       fn generate_accept_channel_v2_message(&self) -> msgs::AcceptChannelV2 {
+               let first_per_commitment_point = self.context.holder_signer.as_ref().get_per_commitment_point(
+                       self.context.cur_holder_commitment_transaction_number, &self.context.secp_ctx);
+               let second_per_commitment_point = self.context.holder_signer.as_ref().get_per_commitment_point(
+                       self.context.cur_holder_commitment_transaction_number - 1, &self.context.secp_ctx);
+               let keys = self.context.get_holder_pubkeys();
+
+               msgs::AcceptChannelV2 {
+                       common_fields: msgs::CommonAcceptChannelFields {
+                               temporary_channel_id: self.context.temporary_channel_id.unwrap(),
+                               dust_limit_satoshis: self.context.holder_dust_limit_satoshis,
+                               max_htlc_value_in_flight_msat: self.context.holder_max_htlc_value_in_flight_msat,
+                               htlc_minimum_msat: self.context.holder_htlc_minimum_msat,
+                               minimum_depth: self.context.minimum_depth.unwrap(),
+                               to_self_delay: self.context.get_holder_selected_contest_delay(),
+                               max_accepted_htlcs: self.context.holder_max_accepted_htlcs,
+                               funding_pubkey: keys.funding_pubkey,
+                               revocation_basepoint: keys.revocation_basepoint.to_public_key(),
+                               payment_basepoint: keys.payment_point,
+                               delayed_payment_basepoint: keys.delayed_payment_basepoint.to_public_key(),
+                               htlc_basepoint: keys.htlc_basepoint.to_public_key(),
+                               first_per_commitment_point,
+                               shutdown_scriptpubkey: Some(match &self.context.shutdown_scriptpubkey {
+                                       Some(script) => script.clone().into_inner(),
+                                       None => Builder::new().into_script(),
+                               }),
+                               channel_type: Some(self.context.channel_type.clone()),
+                       },
+                       funding_satoshis: self.dual_funding_context.our_funding_satoshis,
+                       second_per_commitment_point,
+                       require_confirmed_inputs: None,
+               }
+       }
+
+       /// Enables the possibility for tests to extract a [`msgs::AcceptChannelV2`] message for an
+       /// inbound channel without accepting it.
+       ///
+       /// [`msgs::AcceptChannelV2`]: crate::ln::msgs::AcceptChannelV2
+       #[cfg(test)]
+       pub fn get_accept_channel_v2_message(&self) -> msgs::AcceptChannelV2 {
+               self.generate_accept_channel_v2_message()
+       }
+}
+
+// Unfunded channel utilities
+
+fn get_initial_channel_type(config: &UserConfig, their_features: &InitFeatures) -> ChannelTypeFeatures {
+       // The default channel type (ie the first one we try) depends on whether the channel is
+       // public - if it is, we just go with `only_static_remotekey` as it's the only option
+       // available. If it's private, we first try `scid_privacy` as it provides better privacy
+       // with no other changes, and fall back to `only_static_remotekey`.
+       let mut ret = ChannelTypeFeatures::only_static_remote_key();
+       if !config.channel_handshake_config.announced_channel &&
+               config.channel_handshake_config.negotiate_scid_privacy &&
+               their_features.supports_scid_privacy() {
+               ret.set_scid_privacy_required();
+       }
+
+       // Optionally, if the user would like to negotiate the `anchors_zero_fee_htlc_tx` option, we
+       // set it now. If they don't understand it, we'll fall back to our default of
+       // `only_static_remotekey`.
+       if config.channel_handshake_config.negotiate_anchors_zero_fee_htlc_tx &&
+               their_features.supports_anchors_zero_fee_htlc_tx() {
+               ret.set_anchors_zero_fee_htlc_tx_required();
+       }
+
+       ret
+}
+
+const SERIALIZATION_VERSION: u8 = 4;
 const MIN_SERIALIZATION_VERSION: u8 = 3;
 
 impl_writeable_tlv_based_enum!(InboundHTLCRemovalReason,;
@@ -7851,7 +8369,18 @@ impl<SP: Deref> Writeable for Channel<SP> where SP::Target: SignerProvider {
                // Note that we write out as if remove_uncommitted_htlcs_and_mark_paused had just been
                // called.
 
-               write_ver_prefix!(writer, MIN_SERIALIZATION_VERSION, MIN_SERIALIZATION_VERSION);
+               let version_to_write = if self.context.pending_inbound_htlcs.iter().any(|htlc| match htlc.state {
+                       InboundHTLCState::AwaitingRemoteRevokeToAnnounce(ref htlc_resolution)|
+                               InboundHTLCState::AwaitingAnnouncedRemoteRevoke(ref htlc_resolution) => {
+                               matches!(htlc_resolution, InboundHTLCResolution::Pending { .. })
+                       },
+                       _ => false,
+               }) {
+                       SERIALIZATION_VERSION
+               } else {
+                       MIN_SERIALIZATION_VERSION
+               };
+               write_ver_prefix!(writer, version_to_write, MIN_SERIALIZATION_VERSION);
 
                // `user_id` used to be a single u64 value. In order to remain backwards compatible with
                // versions prior to 0.0.113, the u128 is serialized as two separate u64 values. We write
@@ -7907,13 +8436,29 @@ impl<SP: Deref> Writeable for Channel<SP> where SP::Target: SignerProvider {
                        htlc.payment_hash.write(writer)?;
                        match &htlc.state {
                                &InboundHTLCState::RemoteAnnounced(_) => unreachable!(),
-                               &InboundHTLCState::AwaitingRemoteRevokeToAnnounce(ref htlc_state) => {
+                               &InboundHTLCState::AwaitingRemoteRevokeToAnnounce(ref htlc_resolution) => {
                                        1u8.write(writer)?;
-                                       htlc_state.write(writer)?;
+                                       if version_to_write <= 3 {
+                                               if let InboundHTLCResolution::Resolved { pending_htlc_status } = htlc_resolution {
+                                                       pending_htlc_status.write(writer)?;
+                                               } else {
+                                                       panic!();
+                                               }
+                                       } else {
+                                               htlc_resolution.write(writer)?;
+                                       }
                                },
-                               &InboundHTLCState::AwaitingAnnouncedRemoteRevoke(ref htlc_state) => {
+                               &InboundHTLCState::AwaitingAnnouncedRemoteRevoke(ref htlc_resolution) => {
                                        2u8.write(writer)?;
-                                       htlc_state.write(writer)?;
+                                       if version_to_write <= 3 {
+                                               if let InboundHTLCResolution::Resolved { pending_htlc_status } = htlc_resolution {
+                                                       pending_htlc_status.write(writer)?;
+                                               } else {
+                                                       panic!();
+                                               }
+                                       } else {
+                                               htlc_resolution.write(writer)?;
+                                       }
                                },
                                &InboundHTLCState::Committed => {
                                        3u8.write(writer)?;
@@ -8139,6 +8684,11 @@ impl<SP: Deref> Writeable for Channel<SP> where SP::Target: SignerProvider {
 
                let holder_max_accepted_htlcs = if self.context.holder_max_accepted_htlcs == DEFAULT_MAX_HTLCS { None } else { Some(self.context.holder_max_accepted_htlcs) };
 
+               let mut monitor_pending_update_adds = None;
+               if !self.context.monitor_pending_update_adds.is_empty() {
+                       monitor_pending_update_adds = Some(&self.context.monitor_pending_update_adds);
+               }
+
                write_tlv_fields!(writer, {
                        (0, self.context.announcement_sigs, option),
                        // minimum_depth and counterparty_selected_channel_reserve_satoshis used to have a
@@ -8156,6 +8706,7 @@ impl<SP: Deref> Writeable for Channel<SP> where SP::Target: SignerProvider {
                        (7, self.context.shutdown_scriptpubkey, option),
                        (8, self.context.blocked_monitor_updates, optional_vec),
                        (9, self.context.target_closing_feerate_sats_per_kw, option),
+                       (10, monitor_pending_update_adds, option), // Added in 0.0.122
                        (11, self.context.monitor_pending_finalized_fulfills, required_vec),
                        (13, self.context.channel_creation_height, required),
                        (15, preimages, required_vec),
@@ -8174,7 +8725,8 @@ impl<SP: Deref> Writeable for Channel<SP> where SP::Target: SignerProvider {
                        (39, pending_outbound_blinding_points, optional_vec),
                        (41, holding_cell_blinding_points, optional_vec),
                        (43, malformed_htlcs, optional_vec), // Added in 0.0.119
-                       (45, self.context.local_initiated_shutdown, option), // Added in 0.0.122
+                       // 45 and 47 are reserved for async signing
+                       (49, self.context.local_initiated_shutdown, option), // Added in 0.0.122
                });
 
                Ok(())
@@ -8250,8 +8802,22 @@ impl<'a, 'b, 'c, ES: Deref, SP: Deref> ReadableArgs<(&'a ES, &'b SP, u32, &'c Ch
                                cltv_expiry: Readable::read(reader)?,
                                payment_hash: Readable::read(reader)?,
                                state: match <u8 as Readable>::read(reader)? {
-                                       1 => InboundHTLCState::AwaitingRemoteRevokeToAnnounce(Readable::read(reader)?),
-                                       2 => InboundHTLCState::AwaitingAnnouncedRemoteRevoke(Readable::read(reader)?),
+                                       1 => {
+                                               let resolution = if ver <= 3 {
+                                                       InboundHTLCResolution::Resolved { pending_htlc_status: Readable::read(reader)? }
+                                               } else {
+                                                       Readable::read(reader)?
+                                               };
+                                               InboundHTLCState::AwaitingRemoteRevokeToAnnounce(resolution)
+                                       },
+                                       2 => {
+                                               let resolution = if ver <= 3 {
+                                                       InboundHTLCResolution::Resolved { pending_htlc_status: Readable::read(reader)? }
+                                               } else {
+                                                       Readable::read(reader)?
+                                               };
+                                               InboundHTLCState::AwaitingAnnouncedRemoteRevoke(resolution)
+                                       },
                                        3 => InboundHTLCState::Committed,
                                        4 => InboundHTLCState::LocalRemoved(Readable::read(reader)?),
                                        _ => return Err(DecodeError::InvalidValue),
@@ -8468,6 +9034,7 @@ impl<'a, 'b, 'c, ES: Deref, SP: Deref> ReadableArgs<(&'a ES, &'b SP, u32, &'c Ch
                let mut holding_cell_blinding_points_opt: Option<Vec<Option<PublicKey>>> = None;
 
                let mut malformed_htlcs: Option<Vec<(u64, u16, [u8; 32])>> = None;
+               let mut monitor_pending_update_adds: Option<Vec<msgs::UpdateAddHTLC>> = None;
 
                read_tlv_fields!(reader, {
                        (0, announcement_sigs, option),
@@ -8480,6 +9047,7 @@ impl<'a, 'b, 'c, ES: Deref, SP: Deref> ReadableArgs<(&'a ES, &'b SP, u32, &'c Ch
                        (7, shutdown_scriptpubkey, option),
                        (8, blocked_monitor_updates, optional_vec),
                        (9, target_closing_feerate_sats_per_kw, option),
+                       (10, monitor_pending_update_adds, option), // Added in 0.0.122
                        (11, monitor_pending_finalized_fulfills, optional_vec),
                        (13, channel_creation_height, option),
                        (15, preimages_opt, optional_vec),
@@ -8498,7 +9066,8 @@ impl<'a, 'b, 'c, ES: Deref, SP: Deref> ReadableArgs<(&'a ES, &'b SP, u32, &'c Ch
                        (39, pending_outbound_blinding_points_opt, optional_vec),
                        (41, holding_cell_blinding_points_opt, optional_vec),
                        (43, malformed_htlcs, optional_vec), // Added in 0.0.119
-                       (45, local_initiated_shutdown, option),
+                       // 45 and 47 are reserved for async signing
+                       (49, local_initiated_shutdown, option),
                });
 
                let (channel_keys_id, holder_signer) = if let Some(channel_keys_id) = channel_keys_id {
@@ -8651,6 +9220,7 @@ impl<'a, 'b, 'c, ES: Deref, SP: Deref> ReadableArgs<(&'a ES, &'b SP, u32, &'c Ch
                                monitor_pending_forwards,
                                monitor_pending_failures,
                                monitor_pending_finalized_fulfills: monitor_pending_finalized_fulfills.unwrap(),
+                               monitor_pending_update_adds: monitor_pending_update_adds.unwrap_or(Vec::new()),
 
                                signer_pending_commitment_update: false,
                                signer_pending_funding: false,
@@ -8732,7 +9302,9 @@ impl<'a, 'b, 'c, ES: Deref, SP: Deref> ReadableArgs<(&'a ES, &'b SP, u32, &'c Ch
                                local_initiated_shutdown,
 
                                blocked_monitor_updates: blocked_monitor_updates.unwrap(),
-                       }
+                       },
+                       #[cfg(dual_funding)]
+                       dual_funding_channel_context: None,
                })
        }
 }