Merge pull request #3129 from optout21/splicing-msgs-update
[rust-lightning] / lightning / src / ln / channel.rs
index d6ab1876ae0a31af8dfacc5bac01e35ed438e008..4d166cd60f5c84ed6312592b3e59d5783d501914 100644 (file)
@@ -710,7 +710,7 @@ pub const MIN_THEIR_CHAN_RESERVE_SATOSHIS: u64 = 1000;
 pub(super) enum ChannelError {
        Ignore(String),
        Warn(String),
-       Close(String),
+       Close((String, ClosureReason)),
 }
 
 impl fmt::Debug for ChannelError {
@@ -718,7 +718,7 @@ impl fmt::Debug for ChannelError {
                match self {
                        &ChannelError::Ignore(ref e) => write!(f, "Ignore : {}", e),
                        &ChannelError::Warn(ref e) => write!(f, "Warn : {}", e),
-                       &ChannelError::Close(ref e) => write!(f, "Close : {}", e),
+                       &ChannelError::Close((ref e, _)) => write!(f, "Close : {}", e),
                }
        }
 }
@@ -728,11 +728,17 @@ impl fmt::Display for ChannelError {
                match self {
                        &ChannelError::Ignore(ref e) => write!(f, "{}", e),
                        &ChannelError::Warn(ref e) => write!(f, "{}", e),
-                       &ChannelError::Close(ref e) => write!(f, "{}", e),
+                       &ChannelError::Close((ref e, _)) => write!(f, "{}", e),
                }
        }
 }
 
+impl ChannelError {
+       pub(super) fn close(err: String) -> Self {
+               ChannelError::Close((err.clone(), ClosureReason::ProcessingError { err }))
+       }
+}
+
 pub(super) struct WithChannelContext<'a, L: Deref> where L::Target: Logger {
        pub logger: &'a L,
        pub peer_id: Option<PublicKey>,
@@ -767,7 +773,7 @@ macro_rules! secp_check {
        ($res: expr, $err: expr) => {
                match $res {
                        Ok(thing) => thing,
-                       Err(_) => return Err(ChannelError::Close($err)),
+                       Err(_) => return Err(ChannelError::close($err)),
                }
        };
 }
@@ -1467,90 +1473,90 @@ impl<SP: Deref> ChannelContext<SP> where SP::Target: SignerProvider  {
                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)));
+                       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!(
+                       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)));
+                       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)));
+                       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)));
+                       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)));
+                       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)));
+                       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)));
+                       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()));
+                       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)));
+                       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)));
+                       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)));
+                       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)));
+                       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)));
+                       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)));
+                       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)));
+                       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)));
+                       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()));
+                               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)));
+                       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)));
+                       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)));
+                       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
@@ -1563,14 +1569,14 @@ impl<SP: Deref> ChannelContext<SP> where SP::Target: SignerProvider  {
                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)));
+                       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()));
+                       return Err(ChannelError::close("Insufficient funding amount for initial reserve".to_owned()));
                }
 
                let counterparty_shutdown_scriptpubkey = if their_features.supports_upfront_shutdown_script() {
@@ -1581,14 +1587,14 @@ impl<SP: Deref> ChannelContext<SP> where SP::Target: SignerProvider  {
                                                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)))
+                                                       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()));
+                                       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 };
@@ -1596,19 +1602,19 @@ impl<SP: Deref> ChannelContext<SP> where SP::Target: SignerProvider  {
                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())),
+                               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)));
+                               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())),
+                       Err(_) => return Err(ChannelError::close("Failed to get destination script".to_owned())),
                };
 
                let mut secp_ctx = Secp256k1::new();
@@ -2112,8 +2118,8 @@ impl<SP: Deref> ChannelContext<SP> where SP::Target: SignerProvider  {
 
        /// Returns the holder signer for this channel.
        #[cfg(test)]
-       pub fn get_signer(&self) -> &ChannelSignerType<SP> {
-               return &self.holder_signer
+       pub fn get_mut_signer(&mut self) -> &mut ChannelSignerType<SP> {
+               return &mut self.holder_signer
        }
 
        /// Only allowed immediately after deserialization if get_outbound_scid_alias returns 0,
@@ -2140,6 +2146,143 @@ impl<SP: Deref> ChannelContext<SP> where SP::Target: SignerProvider  {
                }
        }
 
+       /// Performs checks against necessary constraints after receiving either an `accept_channel` or
+       /// `accept_channel2` message.
+       pub fn do_accept_channel_checks(
+               &mut self, default_limits: &ChannelHandshakeLimits, their_features: &InitFeatures,
+               common_fields: &msgs::CommonAcceptChannelFields, channel_reserve_satoshis: u64,
+       ) -> Result<(), ChannelError> {
+               let peer_limits = if let Some(ref limits) = self.inbound_handshake_limits_override { limits } else { default_limits };
+
+               // Check sanity of message fields:
+               if !self.is_outbound() {
+                       return Err(ChannelError::close("Got an accept_channel message from an inbound peer".to_owned()));
+               }
+               if !matches!(self.channel_state, ChannelState::NegotiatingFunding(flags) if flags == NegotiatingFundingFlags::OUR_INIT_SENT) {
+                       return Err(ChannelError::close("Got an accept_channel message at a strange time".to_owned()));
+               }
+               if common_fields.dust_limit_satoshis > 21000000 * 100000000 {
+                       return Err(ChannelError::close(format!("Peer never wants payout outputs? dust_limit_satoshis was {}", common_fields.dust_limit_satoshis)));
+               }
+               if channel_reserve_satoshis > self.channel_value_satoshis {
+                       return Err(ChannelError::close(format!("Bogus channel_reserve_satoshis ({}). Must not be greater than ({})", channel_reserve_satoshis, self.channel_value_satoshis)));
+               }
+               if common_fields.dust_limit_satoshis > self.holder_selected_channel_reserve_satoshis {
+                       return Err(ChannelError::close(format!("Dust limit ({}) is bigger than our channel reserve ({})", common_fields.dust_limit_satoshis, self.holder_selected_channel_reserve_satoshis)));
+               }
+               if channel_reserve_satoshis > self.channel_value_satoshis - self.holder_selected_channel_reserve_satoshis {
+                       return Err(ChannelError::close(format!("Bogus channel_reserve_satoshis ({}). Must not be greater than channel value minus our reserve ({})",
+                               channel_reserve_satoshis, self.channel_value_satoshis - self.holder_selected_channel_reserve_satoshis)));
+               }
+               let full_channel_value_msat = (self.channel_value_satoshis - channel_reserve_satoshis) * 1000;
+               if common_fields.htlc_minimum_msat >= full_channel_value_msat {
+                       return Err(ChannelError::close(format!("Minimum htlc value ({}) is full channel value ({})", common_fields.htlc_minimum_msat, full_channel_value_msat)));
+               }
+               let max_delay_acceptable = u16::min(peer_limits.their_to_self_delay, MAX_LOCAL_BREAKDOWN_TIMEOUT);
+               if common_fields.to_self_delay > max_delay_acceptable {
+                       return Err(ChannelError::close(format!("They wanted our payments to be delayed by a needlessly long period. Upper limit: {}. Actual: {}", max_delay_acceptable, common_fields.to_self_delay)));
+               }
+               if common_fields.max_accepted_htlcs < 1 {
+                       return Err(ChannelError::close("0 max_accepted_htlcs makes for a useless channel".to_owned()));
+               }
+               if common_fields.max_accepted_htlcs > MAX_HTLCS {
+                       return Err(ChannelError::close(format!("max_accepted_htlcs was {}. It must not be larger than {}", common_fields.max_accepted_htlcs, MAX_HTLCS)));
+               }
+
+               // Now check against optional parameters as set by config...
+               if common_fields.htlc_minimum_msat > peer_limits.max_htlc_minimum_msat {
+                       return Err(ChannelError::close(format!("htlc_minimum_msat ({}) is higher than the user specified limit ({})", common_fields.htlc_minimum_msat, peer_limits.max_htlc_minimum_msat)));
+               }
+               if common_fields.max_htlc_value_in_flight_msat < peer_limits.min_max_htlc_value_in_flight_msat {
+                       return Err(ChannelError::close(format!("max_htlc_value_in_flight_msat ({}) is less than the user specified limit ({})", common_fields.max_htlc_value_in_flight_msat, peer_limits.min_max_htlc_value_in_flight_msat)));
+               }
+               if channel_reserve_satoshis > peer_limits.max_channel_reserve_satoshis {
+                       return Err(ChannelError::close(format!("channel_reserve_satoshis ({}) is higher than the user specified limit ({})", channel_reserve_satoshis, peer_limits.max_channel_reserve_satoshis)));
+               }
+               if common_fields.max_accepted_htlcs < peer_limits.min_max_accepted_htlcs {
+                       return Err(ChannelError::close(format!("max_accepted_htlcs ({}) is less than the user specified limit ({})", common_fields.max_accepted_htlcs, peer_limits.min_max_accepted_htlcs)));
+               }
+               if common_fields.dust_limit_satoshis < MIN_CHAN_DUST_LIMIT_SATOSHIS {
+                       return Err(ChannelError::close(format!("dust_limit_satoshis ({}) is less than the implementation limit ({})", common_fields.dust_limit_satoshis, MIN_CHAN_DUST_LIMIT_SATOSHIS)));
+               }
+               if common_fields.dust_limit_satoshis > MAX_CHAN_DUST_LIMIT_SATOSHIS {
+                       return Err(ChannelError::close(format!("dust_limit_satoshis ({}) is greater than the implementation limit ({})", common_fields.dust_limit_satoshis, MAX_CHAN_DUST_LIMIT_SATOSHIS)));
+               }
+               if common_fields.minimum_depth > peer_limits.max_minimum_depth {
+                       return Err(ChannelError::close(format!("We consider the minimum depth to be unreasonably large. Expected minimum: ({}). Actual: ({})", peer_limits.max_minimum_depth, common_fields.minimum_depth)));
+               }
+
+               if let Some(ty) = &common_fields.channel_type {
+                       if *ty != self.channel_type {
+                               return Err(ChannelError::close("Channel Type in accept_channel didn't match the one sent in open_channel.".to_owned()));
+                       }
+               } else if their_features.supports_channel_type() {
+                       // Assume they've accepted the channel type as they said they understand it.
+               } else {
+                       let channel_type = ChannelTypeFeatures::from_init(&their_features);
+                       if channel_type != ChannelTypeFeatures::only_static_remote_key() {
+                               return Err(ChannelError::close("Only static_remote_key is supported for non-negotiated channel types".to_owned()));
+                       }
+                       self.channel_type = channel_type.clone();
+                       self.channel_transaction_parameters.channel_type_features = channel_type;
+               }
+
+               let counterparty_shutdown_scriptpubkey = if their_features.supports_upfront_shutdown_script() {
+                       match &common_fields.shutdown_scriptpubkey {
+                               &Some(ref script) => {
+                                       // Peer is signaling upfront_shutdown and has opt-out with a 0-length script. We don't enforce anything
+                                       if script.len() == 0 {
+                                               None
+                                       } else {
+                                               if !script::is_bolt2_compliant(&script, their_features) {
+                                                       return Err(ChannelError::close(format!("Peer is signaling upfront_shutdown but has provided an unacceptable scriptpubkey format: {}", script)));
+                                               }
+                                               Some(script.clone())
+                                       }
+                               },
+                               // Peer is signaling upfront shutdown but don't opt-out with correct mechanism (a.k.a 0-length script). Peer looks buggy, we fail the channel
+                               &None => {
+                                       return Err(ChannelError::close("Peer is signaling upfront_shutdown but we don't get any script. Use 0-length script to opt-out".to_owned()));
+                               }
+                       }
+               } else { None };
+
+               self.counterparty_dust_limit_satoshis = common_fields.dust_limit_satoshis;
+               self.counterparty_max_htlc_value_in_flight_msat = cmp::min(common_fields.max_htlc_value_in_flight_msat, self.channel_value_satoshis * 1000);
+               self.counterparty_selected_channel_reserve_satoshis = Some(channel_reserve_satoshis);
+               self.counterparty_htlc_minimum_msat = common_fields.htlc_minimum_msat;
+               self.counterparty_max_accepted_htlcs = common_fields.max_accepted_htlcs;
+
+               if peer_limits.trust_own_funding_0conf {
+                       self.minimum_depth = Some(common_fields.minimum_depth);
+               } else {
+                       self.minimum_depth = Some(cmp::max(1, common_fields.minimum_depth));
+               }
+
+               let counterparty_pubkeys = ChannelPublicKeys {
+                       funding_pubkey: common_fields.funding_pubkey,
+                       revocation_basepoint: RevocationBasepoint::from(common_fields.revocation_basepoint),
+                       payment_point: common_fields.payment_basepoint,
+                       delayed_payment_basepoint: DelayedPaymentBasepoint::from(common_fields.delayed_payment_basepoint),
+                       htlc_basepoint: HtlcBasepoint::from(common_fields.htlc_basepoint)
+               };
+
+               self.channel_transaction_parameters.counterparty_parameters = Some(CounterpartyChannelTransactionParameters {
+                       selected_contest_delay: common_fields.to_self_delay,
+                       pubkeys: counterparty_pubkeys,
+               });
+
+               self.counterparty_cur_commitment_point = Some(common_fields.first_per_commitment_point);
+               self.counterparty_shutdown_scriptpubkey = counterparty_shutdown_scriptpubkey;
+
+               self.channel_state = ChannelState::NegotiatingFunding(
+                       NegotiatingFundingFlags::OUR_INIT_SENT | NegotiatingFundingFlags::THEIR_INIT_SENT
+               );
+               self.inbound_handshake_limits_override = None; // We're done enforcing limits on our peer's handshake now.
+
+               Ok(())
+       }
+
        /// Returns the block hash in which our funding transaction was confirmed.
        pub fn get_funding_tx_confirmed_in(&self) -> Option<BlockHash> {
                self.funding_tx_confirmed_in
@@ -2625,7 +2768,7 @@ 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(feerate_per_kw + 2530, feerate_plus_quarter.unwrap_or(u32::max_value()))
+               cmp::max(feerate_per_kw.saturating_add(2530), feerate_plus_quarter.unwrap_or(u32::MAX))
        }
 
        /// Get forwarding information for the counterparty.
@@ -3581,7 +3724,12 @@ impl<SP: Deref> Channel<SP> where
                                        return Ok(());
                                }
                        }
-                       return Err(ChannelError::Close(format!("Peer's feerate much too low. Actual: {}. Our expected lower limit: {}", feerate_per_kw, lower_limit)));
+                       return Err(ChannelError::Close((format!(
+                               "Peer's feerate much too low. Actual: {}. Our expected lower limit: {}", feerate_per_kw, lower_limit
+                       ), ClosureReason::PeerFeerateTooLow {
+                               peer_feerate_sat_per_kw: feerate_per_kw,
+                               required_feerate_sat_per_kw: lower_limit,
+                       })));
                }
                Ok(())
        }
@@ -4031,7 +4179,7 @@ impl<SP: Deref> Channel<SP> where
                        }
                        // If we reconnected before sending our `channel_ready` they may still resend theirs.
                        ChannelState::ChannelReady(_) => check_reconnection = true,
-                       _ => return Err(ChannelError::Close("Peer sent a channel_ready at a strange time".to_owned())),
+                       _ => return Err(ChannelError::close("Peer sent a channel_ready at a strange time".to_owned())),
                }
                if check_reconnection {
                        // They probably disconnected/reconnected and re-sent the channel_ready, which is
@@ -4054,7 +4202,7 @@ impl<SP: Deref> Channel<SP> where
                                                ).expect("We already advanced, so previous secret keys should have been validated already")))
                                };
                        if expected_point != Some(msg.next_per_commitment_point) {
-                               return Err(ChannelError::Close("Peer sent a reconnect channel_ready with a different point".to_owned()));
+                               return Err(ChannelError::close("Peer sent a reconnect channel_ready with a different point".to_owned()));
                        }
                        return Ok(None);
                }
@@ -4072,32 +4220,32 @@ impl<SP: Deref> Channel<SP> where
                fee_estimator: &LowerBoundedFeeEstimator<F>,
        ) -> Result<(), ChannelError> where F::Target: FeeEstimator {
                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()));
+                       return Err(ChannelError::close("Got add HTLC message when channel was not in an operational state".to_owned()));
                }
                // 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()));
+                       return Err(ChannelError::close("Got add HTLC message when channel was not in an operational state".to_owned()));
                }
                if self.context.channel_state.is_peer_disconnected() {
-                       return Err(ChannelError::Close("Peer sent update_add_htlc when we needed a channel_reestablish".to_owned()));
+                       return Err(ChannelError::close("Peer sent update_add_htlc when we needed a channel_reestablish".to_owned()));
                }
                if msg.amount_msat > self.context.channel_value_satoshis * 1000 {
-                       return Err(ChannelError::Close("Remote side tried to send more than the total value of the channel".to_owned()));
+                       return Err(ChannelError::close("Remote side tried to send more than the total value of the channel".to_owned()));
                }
                if msg.amount_msat == 0 {
-                       return Err(ChannelError::Close("Remote side tried to send a 0-msat HTLC".to_owned()));
+                       return Err(ChannelError::close("Remote side tried to send a 0-msat HTLC".to_owned()));
                }
                if msg.amount_msat < self.context.holder_htlc_minimum_msat {
-                       return Err(ChannelError::Close(format!("Remote side tried to send less than our minimum HTLC value. Lower limit: ({}). Actual: ({})", self.context.holder_htlc_minimum_msat, msg.amount_msat)));
+                       return Err(ChannelError::close(format!("Remote side tried to send less than our minimum HTLC value. Lower limit: ({}). Actual: ({})", self.context.holder_htlc_minimum_msat, msg.amount_msat)));
                }
 
                let dust_exposure_limiting_feerate = self.context.get_dust_exposure_limiting_feerate(&fee_estimator);
                let htlc_stats = self.context.get_pending_htlc_stats(None, dust_exposure_limiting_feerate);
                if htlc_stats.pending_inbound_htlcs + 1 > self.context.holder_max_accepted_htlcs as usize {
-                       return Err(ChannelError::Close(format!("Remote tried to push more than our max accepted HTLCs ({})", self.context.holder_max_accepted_htlcs)));
+                       return Err(ChannelError::close(format!("Remote tried to push more than our max accepted HTLCs ({})", self.context.holder_max_accepted_htlcs)));
                }
                if htlc_stats.pending_inbound_htlcs_value_msat + msg.amount_msat > self.context.holder_max_htlc_value_in_flight_msat {
-                       return Err(ChannelError::Close(format!("Remote HTLC add would put them over our max HTLC value ({})", self.context.holder_max_htlc_value_in_flight_msat)));
+                       return Err(ChannelError::close(format!("Remote HTLC add would put them over our max HTLC value ({})", self.context.holder_max_htlc_value_in_flight_msat)));
                }
 
                // Check holder_selected_channel_reserve_satoshis (we're getting paid, so they have to at least meet
@@ -4126,7 +4274,7 @@ impl<SP: Deref> Channel<SP> where
                let pending_remote_value_msat =
                        self.context.channel_value_satoshis * 1000 - pending_value_to_self_msat;
                if pending_remote_value_msat < msg.amount_msat {
-                       return Err(ChannelError::Close("Remote HTLC add would overdraw remaining funds".to_owned()));
+                       return Err(ChannelError::close("Remote HTLC add would overdraw remaining funds".to_owned()));
                }
 
                // Check that the remote can afford to pay for this HTLC on-chain at the current
@@ -4142,10 +4290,10 @@ impl<SP: Deref> Channel<SP> where
                                0
                        };
                        if pending_remote_value_msat.saturating_sub(msg.amount_msat).saturating_sub(anchor_outputs_value_msat) < remote_commit_tx_fee_msat {
-                               return Err(ChannelError::Close("Remote HTLC add would not leave enough to pay for fees".to_owned()));
+                               return Err(ChannelError::close("Remote HTLC add would not leave enough to pay for fees".to_owned()));
                        };
                        if pending_remote_value_msat.saturating_sub(msg.amount_msat).saturating_sub(remote_commit_tx_fee_msat).saturating_sub(anchor_outputs_value_msat) < self.context.holder_selected_channel_reserve_satoshis * 1000 {
-                               return Err(ChannelError::Close("Remote HTLC add would put them under remote reserve value".to_owned()));
+                               return Err(ChannelError::close("Remote HTLC add would put them under remote reserve value".to_owned()));
                        }
                }
 
@@ -4159,14 +4307,14 @@ impl<SP: Deref> Channel<SP> where
                        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);
                        if self.context.value_to_self_msat < self.context.counterparty_selected_channel_reserve_satoshis.unwrap() * 1000 + local_commit_tx_fee_msat + anchor_outputs_value_msat {
-                               return Err(ChannelError::Close("Cannot accept HTLC that would put our balance under counterparty-announced channel reserve value".to_owned()));
+                               return Err(ChannelError::close("Cannot accept HTLC that would put our balance under counterparty-announced channel reserve value".to_owned()));
                        }
                }
                if self.context.next_counterparty_htlc_id != msg.htlc_id {
-                       return Err(ChannelError::Close(format!("Remote skipped HTLC ID (skipped ID: {})", self.context.next_counterparty_htlc_id)));
+                       return Err(ChannelError::close(format!("Remote skipped HTLC ID (skipped ID: {})", self.context.next_counterparty_htlc_id)));
                }
                if msg.cltv_expiry >= 500000000 {
-                       return Err(ChannelError::Close("Remote provided CLTV expiry in seconds instead of block height".to_owned()));
+                       return Err(ChannelError::close("Remote provided CLTV expiry in seconds instead of block height".to_owned()));
                }
 
                if self.context.channel_state.is_local_shutdown_sent() {
@@ -4200,32 +4348,32 @@ impl<SP: Deref> Channel<SP> where
                                        Some(payment_preimage) => {
                                                let payment_hash = PaymentHash(Sha256::hash(&payment_preimage.0[..]).to_byte_array());
                                                if payment_hash != htlc.payment_hash {
-                                                       return Err(ChannelError::Close(format!("Remote tried to fulfill HTLC ({}) with an incorrect preimage", htlc_id)));
+                                                       return Err(ChannelError::close(format!("Remote tried to fulfill HTLC ({}) with an incorrect preimage", htlc_id)));
                                                }
                                                OutboundHTLCOutcome::Success(Some(payment_preimage))
                                        }
                                };
                                match htlc.state {
                                        OutboundHTLCState::LocalAnnounced(_) =>
-                                               return Err(ChannelError::Close(format!("Remote tried to fulfill/fail HTLC ({}) before it had been committed", htlc_id))),
+                                               return Err(ChannelError::close(format!("Remote tried to fulfill/fail HTLC ({}) before it had been committed", htlc_id))),
                                        OutboundHTLCState::Committed => {
                                                htlc.state = OutboundHTLCState::RemoteRemoved(outcome);
                                        },
                                        OutboundHTLCState::AwaitingRemoteRevokeToRemove(_) | OutboundHTLCState::AwaitingRemovedRemoteRevoke(_) | OutboundHTLCState::RemoteRemoved(_) =>
-                                               return Err(ChannelError::Close(format!("Remote tried to fulfill/fail HTLC ({}) that they'd already fulfilled/failed", htlc_id))),
+                                               return Err(ChannelError::close(format!("Remote tried to fulfill/fail HTLC ({}) that they'd already fulfilled/failed", htlc_id))),
                                }
                                return Ok(htlc);
                        }
                }
-               Err(ChannelError::Close("Remote tried to fulfill/fail an HTLC we couldn't find".to_owned()))
+               Err(ChannelError::close("Remote tried to fulfill/fail an HTLC we couldn't find".to_owned()))
        }
 
        pub fn update_fulfill_htlc(&mut self, msg: &msgs::UpdateFulfillHTLC) -> Result<(HTLCSource, u64, Option<u64>), ChannelError> {
                if !matches!(self.context.channel_state, ChannelState::ChannelReady(_)) {
-                       return Err(ChannelError::Close("Got fulfill HTLC message when channel was not in an operational state".to_owned()));
+                       return Err(ChannelError::close("Got fulfill HTLC message when channel was not in an operational state".to_owned()));
                }
                if self.context.channel_state.is_peer_disconnected() {
-                       return Err(ChannelError::Close("Peer sent update_fulfill_htlc when we needed a channel_reestablish".to_owned()));
+                       return Err(ChannelError::close("Peer sent update_fulfill_htlc when we needed a channel_reestablish".to_owned()));
                }
 
                self.mark_outbound_htlc_removed(msg.htlc_id, Some(msg.payment_preimage), None).map(|htlc| (htlc.source.clone(), htlc.amount_msat, htlc.skimmed_fee_msat))
@@ -4233,10 +4381,10 @@ impl<SP: Deref> Channel<SP> where
 
        pub fn update_fail_htlc(&mut self, msg: &msgs::UpdateFailHTLC, fail_reason: HTLCFailReason) -> Result<(), ChannelError> {
                if !matches!(self.context.channel_state, ChannelState::ChannelReady(_)) {
-                       return Err(ChannelError::Close("Got fail HTLC message when channel was not in an operational state".to_owned()));
+                       return Err(ChannelError::close("Got fail HTLC message when channel was not in an operational state".to_owned()));
                }
                if self.context.channel_state.is_peer_disconnected() {
-                       return Err(ChannelError::Close("Peer sent update_fail_htlc when we needed a channel_reestablish".to_owned()));
+                       return Err(ChannelError::close("Peer sent update_fail_htlc when we needed a channel_reestablish".to_owned()));
                }
 
                self.mark_outbound_htlc_removed(msg.htlc_id, None, Some(fail_reason))?;
@@ -4245,10 +4393,10 @@ impl<SP: Deref> Channel<SP> where
 
        pub fn update_fail_malformed_htlc(&mut self, msg: &msgs::UpdateFailMalformedHTLC, fail_reason: HTLCFailReason) -> Result<(), ChannelError> {
                if !matches!(self.context.channel_state, ChannelState::ChannelReady(_)) {
-                       return Err(ChannelError::Close("Got fail malformed HTLC message when channel was not in an operational state".to_owned()));
+                       return Err(ChannelError::close("Got fail malformed HTLC message when channel was not in an operational state".to_owned()));
                }
                if self.context.channel_state.is_peer_disconnected() {
-                       return Err(ChannelError::Close("Peer sent update_fail_malformed_htlc when we needed a channel_reestablish".to_owned()));
+                       return Err(ChannelError::close("Peer sent update_fail_malformed_htlc when we needed a channel_reestablish".to_owned()));
                }
 
                self.mark_outbound_htlc_removed(msg.htlc_id, None, Some(fail_reason))?;
@@ -4259,13 +4407,13 @@ impl<SP: Deref> Channel<SP> where
                where L::Target: Logger
        {
                if !matches!(self.context.channel_state, ChannelState::ChannelReady(_)) {
-                       return Err(ChannelError::Close("Got commitment signed message when channel was not in an operational state".to_owned()));
+                       return Err(ChannelError::close("Got commitment signed message when channel was not in an operational state".to_owned()));
                }
                if self.context.channel_state.is_peer_disconnected() {
-                       return Err(ChannelError::Close("Peer sent commitment_signed when we needed a channel_reestablish".to_owned()));
+                       return Err(ChannelError::close("Peer sent commitment_signed when we needed a channel_reestablish".to_owned()));
                }
                if self.context.channel_state.is_both_sides_shutdown() && self.context.last_sent_closing_fee.is_some() {
-                       return Err(ChannelError::Close("Peer sent commitment_signed after we'd started exchanging closing_signeds".to_owned()));
+                       return Err(ChannelError::close("Peer sent commitment_signed after we'd started exchanging closing_signeds".to_owned()));
                }
 
                let funding_script = self.context.get_funding_redeemscript();
@@ -4283,7 +4431,7 @@ impl<SP: Deref> Channel<SP> where
                                log_bytes!(self.context.counterparty_funding_pubkey().serialize()), encode::serialize_hex(&bitcoin_tx.transaction),
                                log_bytes!(sighash[..]), encode::serialize_hex(&funding_script), &self.context.channel_id());
                        if let Err(_) = self.context.secp_ctx.verify_ecdsa(&sighash, &msg.signature, &self.context.counterparty_funding_pubkey()) {
-                               return Err(ChannelError::Close("Invalid commitment tx signature from peer".to_owned()));
+                               return Err(ChannelError::close("Invalid commitment tx signature from peer".to_owned()));
                        }
                        bitcoin_tx.txid
                };
@@ -4298,7 +4446,7 @@ impl<SP: Deref> Channel<SP> where
                        debug_assert!(!self.context.is_outbound());
                        let counterparty_reserve_we_require_msat = self.context.holder_selected_channel_reserve_satoshis * 1000;
                        if commitment_stats.remote_balance_msat < commitment_stats.total_fee_sat * 1000 + counterparty_reserve_we_require_msat {
-                               return Err(ChannelError::Close("Funding remote cannot afford proposed new fee".to_owned()));
+                               return Err(ChannelError::close("Funding remote cannot afford proposed new fee".to_owned()));
                        }
                }
                #[cfg(any(test, fuzzing))]
@@ -4320,7 +4468,7 @@ impl<SP: Deref> Channel<SP> where
                }
 
                if msg.htlc_signatures.len() != commitment_stats.num_nondust_htlcs {
-                       return Err(ChannelError::Close(format!("Got wrong number of HTLC signatures ({}) from remote. It must be {}", msg.htlc_signatures.len(), commitment_stats.num_nondust_htlcs)));
+                       return Err(ChannelError::close(format!("Got wrong number of HTLC signatures ({}) from remote. It must be {}", msg.htlc_signatures.len(), commitment_stats.num_nondust_htlcs)));
                }
 
                // Up to LDK 0.0.115, HTLC information was required to be duplicated in the
@@ -4353,7 +4501,7 @@ impl<SP: Deref> Channel<SP> where
                                        log_bytes!(msg.htlc_signatures[idx].serialize_compact()[..]), log_bytes!(keys.countersignatory_htlc_key.to_public_key().serialize()),
                                        encode::serialize_hex(&htlc_tx), log_bytes!(htlc_sighash[..]), encode::serialize_hex(&htlc_redeemscript), &self.context.channel_id());
                                if let Err(_) = self.context.secp_ctx.verify_ecdsa(&htlc_sighash, &msg.htlc_signatures[idx], &keys.countersignatory_htlc_key.to_public_key()) {
-                                       return Err(ChannelError::Close("Invalid HTLC tx signature from peer".to_owned()));
+                                       return Err(ChannelError::close("Invalid HTLC tx signature from peer".to_owned()));
                                }
                                if !separate_nondust_htlc_sources {
                                        htlcs_and_sigs.push((htlc, Some(msg.htlc_signatures[idx]), source_opt.take()));
@@ -4378,7 +4526,7 @@ impl<SP: Deref> Channel<SP> where
                );
 
                self.context.holder_signer.as_ref().validate_holder_commitment(&holder_commitment_tx, commitment_stats.outbound_htlc_preimages)
-                       .map_err(|_| ChannelError::Close("Failed to validate our commitment".to_owned()))?;
+                       .map_err(|_| ChannelError::close("Failed to validate our commitment".to_owned()))?;
 
                // Update state now that we've passed all the can-fail calls...
                let mut need_commitment = false;
@@ -4631,20 +4779,20 @@ impl<SP: Deref> Channel<SP> where
        where F::Target: FeeEstimator, L::Target: Logger,
        {
                if !matches!(self.context.channel_state, ChannelState::ChannelReady(_)) {
-                       return Err(ChannelError::Close("Got revoke/ACK message when channel was not in an operational state".to_owned()));
+                       return Err(ChannelError::close("Got revoke/ACK message when channel was not in an operational state".to_owned()));
                }
                if self.context.channel_state.is_peer_disconnected() {
-                       return Err(ChannelError::Close("Peer sent revoke_and_ack when we needed a channel_reestablish".to_owned()));
+                       return Err(ChannelError::close("Peer sent revoke_and_ack when we needed a channel_reestablish".to_owned()));
                }
                if self.context.channel_state.is_both_sides_shutdown() && self.context.last_sent_closing_fee.is_some() {
-                       return Err(ChannelError::Close("Peer sent revoke_and_ack after we'd started exchanging closing_signeds".to_owned()));
+                       return Err(ChannelError::close("Peer sent revoke_and_ack after we'd started exchanging closing_signeds".to_owned()));
                }
 
                let secret = secp_check!(SecretKey::from_slice(&msg.per_commitment_secret), "Peer provided an invalid per_commitment_secret".to_owned());
 
                if let Some(counterparty_prev_commitment_point) = self.context.counterparty_prev_commitment_point {
                        if PublicKey::from_secret_key(&self.context.secp_ctx, &secret) != counterparty_prev_commitment_point {
-                               return Err(ChannelError::Close("Got a revoke commitment secret which didn't correspond to their current pubkey".to_owned()));
+                               return Err(ChannelError::close("Got a revoke commitment secret which didn't correspond to their current pubkey".to_owned()));
                        }
                }
 
@@ -4656,7 +4804,7 @@ impl<SP: Deref> Channel<SP> where
                        // lot of work, and there's some chance this is all a misunderstanding anyway.
                        // We have to do *something*, though, since our signer may get mad at us for otherwise
                        // jumping a remote commitment number, so best to just force-close and move on.
-                       return Err(ChannelError::Close("Received an unexpected revoke_and_ack".to_owned()));
+                       return Err(ChannelError::close("Received an unexpected revoke_and_ack".to_owned()));
                }
 
                #[cfg(any(test, fuzzing))]
@@ -4670,7 +4818,7 @@ impl<SP: Deref> Channel<SP> where
                                ecdsa.validate_counterparty_revocation(
                                        self.context.cur_counterparty_commitment_transaction_number + 1,
                                        &secret
-                               ).map_err(|_| ChannelError::Close("Failed to validate revocation from peer".to_owned()))?;
+                               ).map_err(|_| ChannelError::close("Failed to validate revocation from peer".to_owned()))?;
                        },
                        // TODO (taproot|arik)
                        #[cfg(taproot)]
@@ -4678,7 +4826,7 @@ impl<SP: Deref> Channel<SP> where
                };
 
                self.context.commitment_secrets.provide_secret(self.context.cur_counterparty_commitment_transaction_number + 1, msg.per_commitment_secret)
-                       .map_err(|_| ChannelError::Close("Previous secrets did not match new one".to_owned()))?;
+                       .map_err(|_| ChannelError::close("Previous secrets did not match new one".to_owned()))?;
                self.context.latest_monitor_update_id += 1;
                let mut monitor_update = ChannelMonitorUpdate {
                        update_id: self.context.latest_monitor_update_id,
@@ -5176,14 +5324,34 @@ impl<SP: Deref> Channel<SP> where
                }
        }
 
+       pub fn check_for_stale_feerate<L: Logger>(&mut self, logger: &L, min_feerate: u32) -> Result<(), ClosureReason> {
+               if self.context.is_outbound() {
+                       // While its possible our fee is too low for an outbound channel because we've been
+                       // unable to increase the fee, we don't try to force-close directly here.
+                       return Ok(());
+               }
+               if self.context.feerate_per_kw < min_feerate {
+                       log_info!(logger,
+                               "Closing channel as feerate of {} is below required {} (the minimum required rate over the past day)",
+                               self.context.feerate_per_kw, min_feerate
+                       );
+                       Err(ClosureReason::PeerFeerateTooLow {
+                               peer_feerate_sat_per_kw: self.context.feerate_per_kw,
+                               required_feerate_sat_per_kw: min_feerate,
+                       })
+               } else {
+                       Ok(())
+               }
+       }
+
        pub fn update_fee<F: Deref, L: Deref>(&mut self, fee_estimator: &LowerBoundedFeeEstimator<F>, msg: &msgs::UpdateFee, logger: &L) -> Result<(), ChannelError>
                where F::Target: FeeEstimator, L::Target: Logger
        {
                if self.context.is_outbound() {
-                       return Err(ChannelError::Close("Non-funding remote tried to update channel fee".to_owned()));
+                       return Err(ChannelError::close("Non-funding remote tried to update channel fee".to_owned()));
                }
                if self.context.channel_state.is_peer_disconnected() {
-                       return Err(ChannelError::Close("Peer sent update_fee when we needed a channel_reestablish".to_owned()));
+                       return Err(ChannelError::close("Peer sent update_fee when we needed a channel_reestablish".to_owned()));
                }
                Channel::<SP>::check_remote_fee(&self.context.channel_type, fee_estimator, msg.feerate_per_kw, Some(self.context.feerate_per_kw), logger)?;
 
@@ -5194,11 +5362,11 @@ impl<SP: Deref> Channel<SP> where
                let htlc_stats = self.context.get_pending_htlc_stats(None, dust_exposure_limiting_feerate);
                let max_dust_htlc_exposure_msat = self.context.get_max_dust_htlc_exposure_msat(dust_exposure_limiting_feerate);
                if htlc_stats.on_holder_tx_dust_exposure_msat > max_dust_htlc_exposure_msat {
-                       return Err(ChannelError::Close(format!("Peer sent update_fee with a feerate ({}) which may over-expose us to dust-in-flight on our own transactions (totaling {} msat)",
+                       return Err(ChannelError::close(format!("Peer sent update_fee with a feerate ({}) which may over-expose us to dust-in-flight on our own transactions (totaling {} msat)",
                                msg.feerate_per_kw, htlc_stats.on_holder_tx_dust_exposure_msat)));
                }
                if htlc_stats.on_counterparty_tx_dust_exposure_msat > max_dust_htlc_exposure_msat {
-                       return Err(ChannelError::Close(format!("Peer sent update_fee with a feerate ({}) which may over-expose us to dust-in-flight on our counterparty's transactions (totaling {} msat)",
+                       return Err(ChannelError::close(format!("Peer sent update_fee with a feerate ({}) which may over-expose us to dust-in-flight on our counterparty's transactions (totaling {} msat)",
                                msg.feerate_per_kw, htlc_stats.on_counterparty_tx_dust_exposure_msat)));
                }
                Ok(())
@@ -5360,21 +5528,21 @@ impl<SP: Deref> Channel<SP> where
                        // While BOLT 2 doesn't indicate explicitly we should error this channel here, it
                        // almost certainly indicates we are going to end up out-of-sync in some way, so we
                        // just close here instead of trying to recover.
-                       return Err(ChannelError::Close("Peer sent a loose channel_reestablish not after reconnect".to_owned()));
+                       return Err(ChannelError::close("Peer sent a loose channel_reestablish not after reconnect".to_owned()));
                }
 
                if msg.next_local_commitment_number >= INITIAL_COMMITMENT_NUMBER || msg.next_remote_commitment_number >= INITIAL_COMMITMENT_NUMBER ||
                        msg.next_local_commitment_number == 0 {
-                       return Err(ChannelError::Close("Peer sent an invalid channel_reestablish to force close in a non-standard way".to_owned()));
+                       return Err(ChannelError::close("Peer sent an invalid channel_reestablish to force close in a non-standard way".to_owned()));
                }
 
                let our_commitment_transaction = INITIAL_COMMITMENT_NUMBER - self.context.holder_commitment_point.transaction_number() - 1;
                if msg.next_remote_commitment_number > 0 {
                        let expected_point = self.context.holder_signer.as_ref().get_per_commitment_point(INITIAL_COMMITMENT_NUMBER - msg.next_remote_commitment_number + 1, &self.context.secp_ctx);
                        let given_secret = SecretKey::from_slice(&msg.your_last_per_commitment_secret)
-                               .map_err(|_| ChannelError::Close("Peer sent a garbage channel_reestablish with unparseable secret key".to_owned()))?;
+                               .map_err(|_| ChannelError::close("Peer sent a garbage channel_reestablish with unparseable secret key".to_owned()))?;
                        if expected_point != PublicKey::from_secret_key(&self.context.secp_ctx, &given_secret) {
-                               return Err(ChannelError::Close("Peer sent a garbage channel_reestablish with secret key not matching the commitment height provided".to_owned()));
+                               return Err(ChannelError::close("Peer sent a garbage channel_reestablish with secret key not matching the commitment height provided".to_owned()));
                        }
                        if msg.next_remote_commitment_number > our_commitment_transaction {
                                macro_rules! log_and_panic {
@@ -5418,7 +5586,7 @@ impl<SP: Deref> Channel<SP> where
                        if !self.context.channel_state.is_our_channel_ready() ||
                                        self.context.channel_state.is_monitor_update_in_progress() {
                                if msg.next_remote_commitment_number != 0 {
-                                       return Err(ChannelError::Close("Peer claimed they saw a revoke_and_ack but we haven't sent channel_ready yet".to_owned()));
+                                       return Err(ChannelError::close("Peer claimed they saw a revoke_and_ack but we haven't sent channel_ready yet".to_owned()));
                                }
                                // Short circuit the whole handler as there is nothing we can resend them
                                return Ok(ReestablishResponses {
@@ -5451,7 +5619,7 @@ impl<SP: Deref> Channel<SP> where
                        }
                } else {
                        debug_assert!(false, "All values should have been handled in the four cases above");
-                       return Err(ChannelError::Close(format!(
+                       return Err(ChannelError::close(format!(
                                "Peer attempted to reestablish channel expecting a future local commitment transaction: {} (received) vs {} (expected)",
                                msg.next_remote_commitment_number,
                                our_commitment_transaction
@@ -5509,13 +5677,13 @@ impl<SP: Deref> Channel<SP> where
                                })
                        }
                } else if msg.next_local_commitment_number < next_counterparty_commitment_number {
-                       Err(ChannelError::Close(format!(
+                       Err(ChannelError::close(format!(
                                "Peer attempted to reestablish channel with a very old remote commitment transaction: {} (received) vs {} (expected)",
                                msg.next_local_commitment_number,
                                next_counterparty_commitment_number,
                        )))
                } else {
-                       Err(ChannelError::Close(format!(
+                       Err(ChannelError::close(format!(
                                "Peer attempted to reestablish channel with a future remote commitment transaction: {} (received) vs {} (expected)",
                                msg.next_local_commitment_number,
                                next_counterparty_commitment_number,
@@ -5590,7 +5758,7 @@ impl<SP: Deref> Channel<SP> where
        pub fn timer_check_closing_negotiation_progress(&mut self) -> Result<(), ChannelError> {
                if self.closing_negotiation_ready() {
                        if self.context.closing_signed_in_flight {
-                               return Err(ChannelError::Close("closing_signed negotiation failed to finish within two timer ticks".to_owned()));
+                               return Err(ChannelError::close("closing_signed negotiation failed to finish within two timer ticks".to_owned()));
                        } else {
                                self.context.closing_signed_in_flight = true;
                        }
@@ -5635,7 +5803,7 @@ impl<SP: Deref> Channel<SP> where
                        ChannelSignerType::Ecdsa(ecdsa) => {
                                let sig = ecdsa
                                        .sign_closing_transaction(&closing_tx, &self.context.secp_ctx)
-                                       .map_err(|()| ChannelError::Close("Failed to get signature for closing transaction.".to_owned()))?;
+                                       .map_err(|()| ChannelError::close("Failed to get signature for closing transaction.".to_owned()))?;
 
                                self.context.last_sent_closing_fee = Some((total_fee_satoshis, sig.clone()));
                                Ok((Some(msgs::ClosingSigned {
@@ -5681,17 +5849,17 @@ impl<SP: Deref> Channel<SP> where
        ) -> Result<(Option<msgs::Shutdown>, Option<ChannelMonitorUpdate>, Vec<(HTLCSource, PaymentHash)>), ChannelError>
        {
                if self.context.channel_state.is_peer_disconnected() {
-                       return Err(ChannelError::Close("Peer sent shutdown when we needed a channel_reestablish".to_owned()));
+                       return Err(ChannelError::close("Peer sent shutdown when we needed a channel_reestablish".to_owned()));
                }
                if self.context.channel_state.is_pre_funded_state() {
                        // Spec says we should fail the connection, not the channel, but that's nonsense, there
                        // are plenty of reasons you may want to fail a channel pre-funding, and spec says you
                        // can do that via error message without getting a connection fail anyway...
-                       return Err(ChannelError::Close("Peer sent shutdown pre-funding generation".to_owned()));
+                       return Err(ChannelError::close("Peer sent shutdown pre-funding generation".to_owned()));
                }
                for htlc in self.context.pending_inbound_htlcs.iter() {
                        if let InboundHTLCState::RemoteAnnounced(_) = htlc.state {
-                               return Err(ChannelError::Close("Got shutdown with remote pending HTLCs".to_owned()));
+                               return Err(ChannelError::close("Got shutdown with remote pending HTLCs".to_owned()));
                        }
                }
                assert!(!matches!(self.context.channel_state, ChannelState::ShutdownComplete));
@@ -5719,10 +5887,10 @@ impl<SP: Deref> Channel<SP> where
                                assert!(send_shutdown);
                                let shutdown_scriptpubkey = match signer_provider.get_shutdown_scriptpubkey() {
                                        Ok(scriptpubkey) => scriptpubkey,
-                                       Err(_) => return Err(ChannelError::Close("Failed to get shutdown scriptpubkey".to_owned())),
+                                       Err(_) => return Err(ChannelError::close("Failed to get shutdown scriptpubkey".to_owned())),
                                };
                                if !shutdown_scriptpubkey.is_compatible(their_features) {
-                                       return Err(ChannelError::Close(format!("Provided a scriptpubkey format not accepted by peer: {}", shutdown_scriptpubkey)));
+                                       return Err(ChannelError::close(format!("Provided a scriptpubkey format not accepted by peer: {}", shutdown_scriptpubkey)));
                                }
                                self.context.shutdown_scriptpubkey = Some(shutdown_scriptpubkey);
                                true
@@ -5804,20 +5972,20 @@ impl<SP: Deref> Channel<SP> where
                where F::Target: FeeEstimator
        {
                if !self.context.channel_state.is_both_sides_shutdown() {
-                       return Err(ChannelError::Close("Remote end sent us a closing_signed before both sides provided a shutdown".to_owned()));
+                       return Err(ChannelError::close("Remote end sent us a closing_signed before both sides provided a shutdown".to_owned()));
                }
                if self.context.channel_state.is_peer_disconnected() {
-                       return Err(ChannelError::Close("Peer sent closing_signed when we needed a channel_reestablish".to_owned()));
+                       return Err(ChannelError::close("Peer sent closing_signed when we needed a channel_reestablish".to_owned()));
                }
                if !self.context.pending_inbound_htlcs.is_empty() || !self.context.pending_outbound_htlcs.is_empty() {
-                       return Err(ChannelError::Close("Remote end sent us a closing_signed while there were still pending HTLCs".to_owned()));
+                       return Err(ChannelError::close("Remote end sent us a closing_signed while there were still pending HTLCs".to_owned()));
                }
                if msg.fee_satoshis > TOTAL_BITCOIN_SUPPLY_SATOSHIS { // this is required to stop potential overflow in build_closing_transaction
-                       return Err(ChannelError::Close("Remote tried to send us a closing tx with > 21 million BTC fee".to_owned()));
+                       return Err(ChannelError::close("Remote tried to send us a closing tx with > 21 million BTC fee".to_owned()));
                }
 
                if self.context.is_outbound() && self.context.last_sent_closing_fee.is_none() {
-                       return Err(ChannelError::Close("Remote tried to send a closing_signed when we were supposed to propose the first one".to_owned()));
+                       return Err(ChannelError::close("Remote tried to send a closing_signed when we were supposed to propose the first one".to_owned()));
                }
 
                if self.context.channel_state.is_monitor_update_in_progress() {
@@ -5828,7 +5996,7 @@ impl<SP: Deref> Channel<SP> where
                let funding_redeemscript = self.context.get_funding_redeemscript();
                let (mut closing_tx, used_total_fee) = self.build_closing_transaction(msg.fee_satoshis, false);
                if used_total_fee != msg.fee_satoshis {
-                       return Err(ChannelError::Close(format!("Remote sent us a closing_signed with a fee other than the value they can claim. Fee in message: {}. Actual closing tx fee: {}", msg.fee_satoshis, used_total_fee)));
+                       return Err(ChannelError::close(format!("Remote sent us a closing_signed with a fee other than the value they can claim. Fee in message: {}. Actual closing tx fee: {}", msg.fee_satoshis, used_total_fee)));
                }
                let sighash = closing_tx.trust().get_sighash_all(&funding_redeemscript, self.context.channel_value_satoshis);
 
@@ -5845,7 +6013,7 @@ impl<SP: Deref> Channel<SP> where
 
                for outp in closing_tx.trust().built_transaction().output.iter() {
                        if !outp.script_pubkey.is_witness_program() && outp.value < Amount::from_sat(MAX_STD_OUTPUT_DUST_LIMIT_SATOSHIS) {
-                               return Err(ChannelError::Close("Remote sent us a closing_signed with a dust output. Always use segwit closing scripts!".to_owned()));
+                               return Err(ChannelError::close("Remote sent us a closing_signed with a dust output. Always use segwit closing scripts!".to_owned()));
                        }
                }
 
@@ -5891,7 +6059,7 @@ impl<SP: Deref> Channel<SP> where
                                        ChannelSignerType::Ecdsa(ecdsa) => {
                                                let sig = ecdsa
                                                        .sign_closing_transaction(&closing_tx, &self.context.secp_ctx)
-                                                       .map_err(|_| ChannelError::Close("External signer refused to sign closing transaction".to_owned()))?;
+                                                       .map_err(|_| ChannelError::close("External signer refused to sign closing transaction".to_owned()))?;
                                                let (signed_tx, shutdown_result) = if $new_fee == msg.fee_satoshis {
                                                        let shutdown_result = ShutdownResult {
                                                                closure_reason,
@@ -5933,7 +6101,7 @@ impl<SP: Deref> Channel<SP> where
 
                if let Some(msgs::ClosingSignedFeeRange { min_fee_satoshis, max_fee_satoshis }) = msg.fee_range {
                        if msg.fee_satoshis < min_fee_satoshis || msg.fee_satoshis > max_fee_satoshis {
-                               return Err(ChannelError::Close(format!("Peer sent a bogus closing_signed - suggested fee of {} sat was not in their desired range of {} sat - {} sat", msg.fee_satoshis, min_fee_satoshis, max_fee_satoshis)));
+                               return Err(ChannelError::close(format!("Peer sent a bogus closing_signed - suggested fee of {} sat was not in their desired range of {} sat - {} sat", msg.fee_satoshis, min_fee_satoshis, max_fee_satoshis)));
                        }
                        if max_fee_satoshis < our_min_fee {
                                return Err(ChannelError::Warn(format!("Unable to come to consensus about closing feerate, remote's max fee ({} sat) was smaller than our min fee ({} sat)", max_fee_satoshis, our_min_fee)));
@@ -5949,7 +6117,7 @@ impl<SP: Deref> Channel<SP> where
                                propose_fee!(cmp::min(max_fee_satoshis, our_max_fee));
                        } else {
                                if msg.fee_satoshis < our_min_fee || msg.fee_satoshis > our_max_fee {
-                                       return Err(ChannelError::Close(format!("Peer sent a bogus closing_signed - suggested fee of {} sat was not in our desired range of {} sat - {} sat after we informed them of our range.",
+                                       return Err(ChannelError::close(format!("Peer sent a bogus closing_signed - suggested fee of {} sat was not in our desired range of {} sat - {} sat after we informed them of our range.",
                                                msg.fee_satoshis, our_min_fee, our_max_fee)));
                                }
                                // The proposed fee is in our acceptable range, accept it and broadcast!
@@ -5965,7 +6133,7 @@ impl<SP: Deref> Channel<SP> where
                                        } else if last_fee < our_max_fee {
                                                propose_fee!(our_max_fee);
                                        } else {
-                                               return Err(ChannelError::Close(format!("Unable to come to consensus about closing feerate, remote wants something ({} sat) higher than our max fee ({} sat)", msg.fee_satoshis, our_max_fee)));
+                                               return Err(ChannelError::close(format!("Unable to come to consensus about closing feerate, remote wants something ({} sat) higher than our max fee ({} sat)", msg.fee_satoshis, our_max_fee)));
                                        }
                                } else {
                                        if msg.fee_satoshis > our_min_fee {
@@ -5973,7 +6141,7 @@ impl<SP: Deref> Channel<SP> where
                                        } else if last_fee > our_min_fee {
                                                propose_fee!(our_min_fee);
                                        } else {
-                                               return Err(ChannelError::Close(format!("Unable to come to consensus about closing feerate, remote wants something ({} sat) lower than our min fee ({} sat)", msg.fee_satoshis, our_min_fee)));
+                                               return Err(ChannelError::close(format!("Unable to come to consensus about closing feerate, remote wants something ({} sat) lower than our min fee ({} sat)", msg.fee_satoshis, our_min_fee)));
                                        }
                                }
                        } else {
@@ -6740,12 +6908,12 @@ impl<SP: Deref> Channel<SP> where
                let msghash = hash_to_message!(&Sha256d::hash(&announcement.encode()[..])[..]);
 
                if self.context.secp_ctx.verify_ecdsa(&msghash, &msg.node_signature, &self.context.get_counterparty_node_id()).is_err() {
-                       return Err(ChannelError::Close(format!(
+                       return Err(ChannelError::close(format!(
                                "Bad announcement_signatures. Failed to verify node_signature. UnsignedChannelAnnouncement used for verification is {:?}. their_node_key is {:?}",
                                 &announcement, self.context.get_counterparty_node_id())));
                }
                if self.context.secp_ctx.verify_ecdsa(&msghash, &msg.bitcoin_signature, self.context.counterparty_funding_pubkey()).is_err() {
-                       return Err(ChannelError::Close(format!(
+                       return Err(ChannelError::close(format!(
                                "Bad announcement_signatures. Failed to verify bitcoin_signature. UnsignedChannelAnnouncement used for verification is {:?}. their_bitcoin_key is ({:?})",
                                &announcement, self.context.counterparty_funding_pubkey())));
                }
@@ -7104,6 +7272,7 @@ impl<SP: Deref> Channel<SP> where
                                        channel_id: self.context.channel_id,
                                        signature,
                                        htlc_signatures,
+                                       batch: None,
                                        #[cfg(taproot)]
                                        partial_signature_with_nonce: None,
                                }, (counterparty_commitment_txid, commitment_stats.htlcs_included)))
@@ -7466,136 +7635,11 @@ impl<SP: Deref> OutboundV1Channel<SP> where SP::Target: SignerProvider {
        }
 
        // Message handlers
-       pub fn accept_channel(&mut self, msg: &msgs::AcceptChannel, default_limits: &ChannelHandshakeLimits, their_features: &InitFeatures) -> Result<(), ChannelError> {
-               let peer_limits = if let Some(ref limits) = self.context.inbound_handshake_limits_override { limits } else { default_limits };
-
-               // Check sanity of message fields:
-               if !self.context.is_outbound() {
-                       return Err(ChannelError::Close("Got an accept_channel message from an inbound peer".to_owned()));
-               }
-               if !matches!(self.context.channel_state, ChannelState::NegotiatingFunding(flags) if flags == NegotiatingFundingFlags::OUR_INIT_SENT) {
-                       return Err(ChannelError::Close("Got an accept_channel message at a strange time".to_owned()));
-               }
-               if msg.common_fields.dust_limit_satoshis > 21000000 * 100000000 {
-                       return Err(ChannelError::Close(format!("Peer never wants payout outputs? dust_limit_satoshis was {}", msg.common_fields.dust_limit_satoshis)));
-               }
-               if msg.channel_reserve_satoshis > self.context.channel_value_satoshis {
-                       return Err(ChannelError::Close(format!("Bogus channel_reserve_satoshis ({}). Must not be greater than ({})", msg.channel_reserve_satoshis, self.context.channel_value_satoshis)));
-               }
-               if msg.common_fields.dust_limit_satoshis > self.context.holder_selected_channel_reserve_satoshis {
-                       return Err(ChannelError::Close(format!("Dust limit ({}) is bigger than our channel reserve ({})", msg.common_fields.dust_limit_satoshis, self.context.holder_selected_channel_reserve_satoshis)));
-               }
-               if msg.channel_reserve_satoshis > self.context.channel_value_satoshis - self.context.holder_selected_channel_reserve_satoshis {
-                       return Err(ChannelError::Close(format!("Bogus channel_reserve_satoshis ({}). Must not be greater than channel value minus our reserve ({})",
-                               msg.channel_reserve_satoshis, self.context.channel_value_satoshis - self.context.holder_selected_channel_reserve_satoshis)));
-               }
-               let full_channel_value_msat = (self.context.channel_value_satoshis - msg.channel_reserve_satoshis) * 1000;
-               if msg.common_fields.htlc_minimum_msat >= full_channel_value_msat {
-                       return Err(ChannelError::Close(format!("Minimum htlc value ({}) is full channel value ({})", msg.common_fields.htlc_minimum_msat, full_channel_value_msat)));
-               }
-               let max_delay_acceptable = u16::min(peer_limits.their_to_self_delay, MAX_LOCAL_BREAKDOWN_TIMEOUT);
-               if msg.common_fields.to_self_delay > max_delay_acceptable {
-                       return Err(ChannelError::Close(format!("They wanted our payments to be delayed by a needlessly long period. Upper limit: {}. Actual: {}", max_delay_acceptable, msg.common_fields.to_self_delay)));
-               }
-               if msg.common_fields.max_accepted_htlcs < 1 {
-                       return Err(ChannelError::Close("0 max_accepted_htlcs makes for a useless channel".to_owned()));
-               }
-               if msg.common_fields.max_accepted_htlcs > MAX_HTLCS {
-                       return Err(ChannelError::Close(format!("max_accepted_htlcs was {}. It must not be larger than {}", msg.common_fields.max_accepted_htlcs, MAX_HTLCS)));
-               }
-
-               // Now check against optional parameters as set by config...
-               if msg.common_fields.htlc_minimum_msat > peer_limits.max_htlc_minimum_msat {
-                       return Err(ChannelError::Close(format!("htlc_minimum_msat ({}) is higher than the user specified limit ({})", msg.common_fields.htlc_minimum_msat, peer_limits.max_htlc_minimum_msat)));
-               }
-               if msg.common_fields.max_htlc_value_in_flight_msat < peer_limits.min_max_htlc_value_in_flight_msat {
-                       return Err(ChannelError::Close(format!("max_htlc_value_in_flight_msat ({}) is less than the user specified limit ({})", msg.common_fields.max_htlc_value_in_flight_msat, peer_limits.min_max_htlc_value_in_flight_msat)));
-               }
-               if msg.channel_reserve_satoshis > peer_limits.max_channel_reserve_satoshis {
-                       return Err(ChannelError::Close(format!("channel_reserve_satoshis ({}) is higher than the user specified limit ({})", msg.channel_reserve_satoshis, peer_limits.max_channel_reserve_satoshis)));
-               }
-               if msg.common_fields.max_accepted_htlcs < peer_limits.min_max_accepted_htlcs {
-                       return Err(ChannelError::Close(format!("max_accepted_htlcs ({}) is less than the user specified limit ({})", msg.common_fields.max_accepted_htlcs, peer_limits.min_max_accepted_htlcs)));
-               }
-               if msg.common_fields.dust_limit_satoshis < MIN_CHAN_DUST_LIMIT_SATOSHIS {
-                       return Err(ChannelError::Close(format!("dust_limit_satoshis ({}) is less than the implementation limit ({})", msg.common_fields.dust_limit_satoshis, MIN_CHAN_DUST_LIMIT_SATOSHIS)));
-               }
-               if msg.common_fields.dust_limit_satoshis > MAX_CHAN_DUST_LIMIT_SATOSHIS {
-                       return Err(ChannelError::Close(format!("dust_limit_satoshis ({}) is greater than the implementation limit ({})", msg.common_fields.dust_limit_satoshis, MAX_CHAN_DUST_LIMIT_SATOSHIS)));
-               }
-               if msg.common_fields.minimum_depth > peer_limits.max_minimum_depth {
-                       return Err(ChannelError::Close(format!("We consider the minimum depth to be unreasonably large. Expected minimum: ({}). Actual: ({})", peer_limits.max_minimum_depth, msg.common_fields.minimum_depth)));
-               }
-
-               if let Some(ty) = &msg.common_fields.channel_type {
-                       if *ty != self.context.channel_type {
-                               return Err(ChannelError::Close("Channel Type in accept_channel didn't match the one sent in open_channel.".to_owned()));
-                       }
-               } else if their_features.supports_channel_type() {
-                       // Assume they've accepted the channel type as they said they understand it.
-               } else {
-                       let channel_type = ChannelTypeFeatures::from_init(&their_features);
-                       if channel_type != ChannelTypeFeatures::only_static_remote_key() {
-                               return Err(ChannelError::Close("Only static_remote_key is supported for non-negotiated channel types".to_owned()));
-                       }
-                       self.context.channel_type = channel_type.clone();
-                       self.context.channel_transaction_parameters.channel_type_features = channel_type;
-               }
-
-               let counterparty_shutdown_scriptpubkey = if their_features.supports_upfront_shutdown_script() {
-                       match &msg.common_fields.shutdown_scriptpubkey {
-                               &Some(ref script) => {
-                                       // Peer is signaling upfront_shutdown and has opt-out with a 0-length script. We don't enforce anything
-                                       if script.len() == 0 {
-                                               None
-                                       } else {
-                                               if !script::is_bolt2_compliant(&script, their_features) {
-                                                       return Err(ChannelError::Close(format!("Peer is signaling upfront_shutdown but has provided an unacceptable scriptpubkey format: {}", script)));
-                                               }
-                                               Some(script.clone())
-                                       }
-                               },
-                               // Peer is signaling upfront shutdown but don't opt-out with correct mechanism (a.k.a 0-length script). Peer looks buggy, we fail the channel
-                               &None => {
-                                       return Err(ChannelError::Close("Peer is signaling upfront_shutdown but we don't get any script. Use 0-length script to opt-out".to_owned()));
-                               }
-                       }
-               } else { None };
-
-               self.context.counterparty_dust_limit_satoshis = msg.common_fields.dust_limit_satoshis;
-               self.context.counterparty_max_htlc_value_in_flight_msat = cmp::min(msg.common_fields.max_htlc_value_in_flight_msat, self.context.channel_value_satoshis * 1000);
-               self.context.counterparty_selected_channel_reserve_satoshis = Some(msg.channel_reserve_satoshis);
-               self.context.counterparty_htlc_minimum_msat = msg.common_fields.htlc_minimum_msat;
-               self.context.counterparty_max_accepted_htlcs = msg.common_fields.max_accepted_htlcs;
-
-               if peer_limits.trust_own_funding_0conf {
-                       self.context.minimum_depth = Some(msg.common_fields.minimum_depth);
-               } else {
-                       self.context.minimum_depth = Some(cmp::max(1, msg.common_fields.minimum_depth));
-               }
-
-               let counterparty_pubkeys = ChannelPublicKeys {
-                       funding_pubkey: msg.common_fields.funding_pubkey,
-                       revocation_basepoint: RevocationBasepoint::from(msg.common_fields.revocation_basepoint),
-                       payment_point: msg.common_fields.payment_basepoint,
-                       delayed_payment_basepoint: DelayedPaymentBasepoint::from(msg.common_fields.delayed_payment_basepoint),
-                       htlc_basepoint: HtlcBasepoint::from(msg.common_fields.htlc_basepoint)
-               };
-
-               self.context.channel_transaction_parameters.counterparty_parameters = Some(CounterpartyChannelTransactionParameters {
-                       selected_contest_delay: msg.common_fields.to_self_delay,
-                       pubkeys: counterparty_pubkeys,
-               });
-
-               self.context.counterparty_cur_commitment_point = Some(msg.common_fields.first_per_commitment_point);
-               self.context.counterparty_shutdown_scriptpubkey = counterparty_shutdown_scriptpubkey;
-
-               self.context.channel_state = ChannelState::NegotiatingFunding(
-                       NegotiatingFundingFlags::OUR_INIT_SENT | NegotiatingFundingFlags::THEIR_INIT_SENT
-               );
-               self.context.inbound_handshake_limits_override = None; // We're done enforcing limits on our peer's handshake now.
-
-               Ok(())
+       pub fn accept_channel(
+               &mut self, msg: &msgs::AcceptChannel, default_limits: &ChannelHandshakeLimits,
+               their_features: &InitFeatures
+       ) -> Result<(), ChannelError> {
+               self.context.do_accept_channel_checks(default_limits, their_features, &msg.common_fields, msg.channel_reserve_satoshis)
        }
 
        /// Handles a funding_signed message from the remote end.
@@ -7607,10 +7651,10 @@ impl<SP: Deref> OutboundV1Channel<SP> where SP::Target: SignerProvider {
                L::Target: Logger
        {
                if !self.context.is_outbound() {
-                       return Err((self, ChannelError::Close("Received funding_signed for an inbound channel?".to_owned())));
+                       return Err((self, ChannelError::close("Received funding_signed for an inbound channel?".to_owned())));
                }
                if !matches!(self.context.channel_state, ChannelState::FundingNegotiated) {
-                       return Err((self, ChannelError::Close("Received funding_signed in strange state!".to_owned())));
+                       return Err((self, ChannelError::close("Received funding_signed in strange state!".to_owned())));
                }
                if self.context.commitment_secrets.get_min_seen_secret() != (1 << 48) ||
                                self.context.cur_counterparty_commitment_transaction_number != INITIAL_COMMITMENT_NUMBER ||
@@ -7636,7 +7680,7 @@ impl<SP: Deref> OutboundV1Channel<SP> where SP::Target: SignerProvider {
                        let sighash = initial_commitment_bitcoin_tx.get_sighash_all(&funding_script, self.context.channel_value_satoshis);
                        // They sign our commitment transaction, allowing us to broadcast the tx if we wish.
                        if let Err(_) = self.context.secp_ctx.verify_ecdsa(&sighash, &msg.signature, &self.context.get_counterparty_pubkeys().funding_pubkey) {
-                               return Err((self, ChannelError::Close("Invalid funding_signed signature from peer".to_owned())));
+                               return Err((self, ChannelError::close("Invalid funding_signed signature from peer".to_owned())));
                        }
                }
 
@@ -7651,7 +7695,7 @@ impl<SP: Deref> OutboundV1Channel<SP> where SP::Target: SignerProvider {
                let validated =
                        self.context.holder_signer.as_ref().validate_holder_commitment(&holder_commitment_tx, Vec::new());
                if validated.is_err() {
-                       return Err((self, ChannelError::Close("Failed to validate our commitment".to_owned())));
+                       return Err((self, ChannelError::close("Failed to validate our commitment".to_owned())));
                }
 
                let funding_redeemscript = self.context.get_funding_redeemscript();
@@ -7723,28 +7767,28 @@ pub(super) fn channel_type_from_open_channel(
 ) -> Result<ChannelTypeFeatures, ChannelError> {
        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()));
+                       return Err(ChannelError::close("Channel Type field contained optional bits - this is not allowed".to_owned()));
                }
 
                // We only support the channel types defined by the `ChannelManager` in
                // `provided_channel_type_features`. The channel type must always support
                // `static_remote_key`.
                if !channel_type.requires_static_remote_key() {
-                       return Err(ChannelError::Close("Channel Type was not understood - we require static remote key".to_owned()));
+                       return Err(ChannelError::close("Channel Type was not understood - we require static remote key".to_owned()));
                }
                // Make sure we support all of the features behind the channel type.
                if !channel_type.is_subset(our_supported_features) {
-                       return Err(ChannelError::Close("Channel Type contains unsupported features".to_owned()));
+                       return Err(ChannelError::close("Channel Type contains unsupported features".to_owned()));
                }
                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()));
+                       return Err(ChannelError::close("SCID Alias/Privacy Channel Type cannot be set on a public channel".to_owned()));
                }
                Ok(channel_type.clone())
        } else {
                let channel_type = ChannelTypeFeatures::from_init(&their_features);
                if channel_type != ChannelTypeFeatures::only_static_remote_key() {
-                       return Err(ChannelError::Close("Only static_remote_key is supported for non-negotiated channel types".to_owned()));
+                       return Err(ChannelError::close("Only static_remote_key is supported for non-negotiated channel types".to_owned()));
                }
                Ok(channel_type)
        }
@@ -7896,7 +7940,7 @@ impl<SP: Deref> InboundV1Channel<SP> where SP::Target: SignerProvider {
                L::Target: Logger
        {
                if self.context.is_outbound() {
-                       return Err((self, ChannelError::Close("Received funding_created for an outbound channel?".to_owned())));
+                       return Err((self, ChannelError::close("Received funding_created for an outbound channel?".to_owned())));
                }
                if !matches!(
                        self.context.channel_state, ChannelState::NegotiatingFunding(flags)
@@ -7905,7 +7949,7 @@ impl<SP: Deref> InboundV1Channel<SP> where SP::Target: SignerProvider {
                        // BOLT 2 says that if we disconnect before we send funding_signed we SHOULD NOT
                        // remember the channel, so it's safe to just send an error_message here and drop the
                        // channel.
-                       return Err((self, ChannelError::Close("Received funding_created after we got the channel!".to_owned())));
+                       return Err((self, ChannelError::close("Received funding_created after we got the channel!".to_owned())));
                }
                if self.context.commitment_secrets.get_min_seen_secret() != (1 << 48) ||
                                self.context.cur_counterparty_commitment_transaction_number != INITIAL_COMMITMENT_NUMBER ||
@@ -7941,7 +7985,7 @@ impl<SP: Deref> InboundV1Channel<SP> where SP::Target: SignerProvider {
                );
 
                if let Err(_) = self.context.holder_signer.as_ref().validate_holder_commitment(&holder_commitment_tx, Vec::new()) {
-                       return Err((self, ChannelError::Close("Failed to validate our commitment".to_owned())));
+                       return Err((self, ChannelError::close("Failed to validate our commitment".to_owned())));
                }
 
                // Now that we're past error-generating stuff, update our local state:
@@ -8145,7 +8189,7 @@ impl<SP: Deref> InboundV2Channel<SP> where SP::Target: SignerProvider {
                // 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",
+                       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)?;