Take the full funding transaction from the user on generation
[rust-lightning] / lightning / src / ln / channel.rs
index 95dcde2c25c6ba1bd3210fd34a54af6a2e4cb1b6..174aecd3ba036f46dc9acdc95d2b287ef536d812 100644 (file)
@@ -25,7 +25,7 @@ use bitcoin::secp256k1;
 use ln::features::{ChannelFeatures, InitFeatures};
 use ln::msgs;
 use ln::msgs::{DecodeError, OptionalField, DataLossProtect};
-use ln::channelmanager::{PendingHTLCStatus, HTLCSource, HTLCFailReason, HTLCFailureMsg, PendingHTLCInfo, RAACommitmentOrder, PaymentPreimage, PaymentHash, BREAKDOWN_TIMEOUT, MAX_LOCAL_BREAKDOWN_TIMEOUT};
+use ln::channelmanager::{PendingHTLCStatus, HTLCSource, HTLCFailReason, HTLCFailureMsg, PendingHTLCInfo, RAACommitmentOrder, PaymentPreimage, PaymentHash, BREAKDOWN_TIMEOUT, MIN_CLTV_EXPIRY_DELTA, MAX_LOCAL_BREAKDOWN_TIMEOUT};
 use ln::chan_utils::{CounterpartyCommitmentSecrets, TxCreationKeys, HTLCOutputInCommitment, HTLC_SUCCESS_TX_WEIGHT, HTLC_TIMEOUT_TX_WEIGHT, make_funding_redeemscript, ChannelPublicKeys, CommitmentTransaction, HolderCommitmentTransaction, ChannelTransactionParameters, CounterpartyChannelTransactionParameters, MAX_HTLCS, get_commitment_transaction_number_obscure_factor};
 use ln::chan_utils;
 use chain::chaininterface::{FeeEstimator,ConfirmationTarget};
@@ -37,9 +37,9 @@ use util::ser::{Readable, ReadableArgs, Writeable, Writer, VecWriter};
 use util::logger::Logger;
 use util::errors::APIError;
 use util::config::{UserConfig,ChannelConfig};
+use util::scid_utils::scid_from_parts;
 
 use std;
-use std::default::Default;
 use std::{cmp,mem,fmt};
 use std::ops::Deref;
 #[cfg(any(test, feature = "fuzztarget"))]
@@ -96,6 +96,7 @@ enum InboundHTLCState {
        /// is used to derive commitment keys, which are used to construct the
        /// signatures in a commitment_signed message.
        /// Implies AwaitingRemoteRevoke.
+       ///
        /// [BOLT #2]: https://github.com/lightningnetwork/lightning-rfc/blob/master/02-peer-protocol.md
        AwaitingRemoteRevokeToAnnounce(PendingHTLCStatus),
        /// Included in a received commitment_signed message (implying we've revoke_and_ack'd it).
@@ -282,6 +283,19 @@ impl HTLCCandidate {
        }
 }
 
+/// Information needed for constructing an invoice route hint for this channel.
+#[derive(Clone)]
+pub struct CounterpartyForwardingInfo {
+       /// Base routing fee in millisatoshis.
+       pub fee_base_msat: u32,
+       /// Amount in millionths of a satoshi the channel will charge per transferred satoshi.
+       pub fee_proportional_millionths: u32,
+       /// The minimum difference in cltv_expiry between an ingoing HTLC and its outgoing counterpart,
+       /// such that the outgoing HTLC is forwardable to this counterparty. See `msgs::ChannelUpdate`'s
+       /// `cltv_expiry_delta` for more details.
+       pub cltv_expiry_delta: u16,
+}
+
 // TODO: We should refactor this to be an Inbound/OutboundChannel until initial setup handshaking
 // has been completed, and then turn into a Channel to get compiler-time enforcement of things like
 // calling channel_id() before we're set up or things like get_outbound_funding_signed on an
@@ -368,9 +382,6 @@ pub(super) struct Channel<Signer: Sign> {
        /// could miss the funding_tx_confirmed_in block as well, but it serves as a useful fallback.
        funding_tx_confirmed_in: Option<BlockHash>,
        short_channel_id: Option<u64>,
-       /// Used to deduplicate block_connected callbacks, also used to verify consistency during
-       /// ChannelManager deserialization (hence pub(super))
-       pub(super) last_block_connected: BlockHash,
        funding_tx_confirmations: u64,
 
        counterparty_dust_limit_satoshis: u64,
@@ -395,10 +406,12 @@ pub(super) struct Channel<Signer: Sign> {
        //implied by OUR_MAX_HTLCS: max_accepted_htlcs: u16,
        minimum_depth: u32,
 
+       counterparty_forwarding_info: Option<CounterpartyForwardingInfo>,
+
        pub(crate) channel_transaction_parameters: ChannelTransactionParameters,
+       funding_transaction: Option<Transaction>,
 
        counterparty_cur_commitment_point: Option<PublicKey>,
-
        counterparty_prev_commitment_point: Option<PublicKey>,
        counterparty_node_id: PublicKey,
 
@@ -521,13 +534,16 @@ impl<Signer: Sign> Channel<Signer> {
 
                let feerate = fee_estimator.get_est_sat_per_1000_weight(ConfirmationTarget::Normal);
 
+               let mut secp_ctx = Secp256k1::new();
+               secp_ctx.seeded_randomize(&keys_provider.get_secure_random_bytes());
+
                Ok(Channel {
                        user_id,
                        config: config.channel_options.clone(),
 
                        channel_id: keys_provider.get_secure_random_bytes(),
                        channel_state: ChannelState::OurInitSent as u32,
-                       secp_ctx: Secp256k1::new(),
+                       secp_ctx,
                        channel_value_satoshis,
 
                        latest_monitor_update_id: 0,
@@ -566,7 +582,6 @@ impl<Signer: Sign> Channel<Signer> {
 
                        funding_tx_confirmed_in: None,
                        short_channel_id: None,
-                       last_block_connected: Default::default(),
                        funding_tx_confirmations: 0,
 
                        feerate_per_kw: feerate,
@@ -579,6 +594,8 @@ impl<Signer: Sign> Channel<Signer> {
                        counterparty_max_accepted_htlcs: 0,
                        minimum_depth: 0, // Filled in in accept_channel
 
+                       counterparty_forwarding_info: None,
+
                        channel_transaction_parameters: ChannelTransactionParameters {
                                holder_pubkeys: pubkeys,
                                holder_selected_contest_delay: config.own_channel_config.our_to_self_delay,
@@ -586,8 +603,9 @@ impl<Signer: Sign> Channel<Signer> {
                                counterparty_parameters: None,
                                funding_outpoint: None
                        },
-                       counterparty_cur_commitment_point: None,
+                       funding_transaction: None,
 
+                       counterparty_cur_commitment_point: None,
                        counterparty_prev_commitment_point: None,
                        counterparty_node_id,
 
@@ -755,13 +773,16 @@ impl<Signer: Sign> Channel<Signer> {
                        }
                } else { None };
 
+               let mut secp_ctx = Secp256k1::new();
+               secp_ctx.seeded_randomize(&keys_provider.get_secure_random_bytes());
+
                let chan = Channel {
                        user_id,
                        config: local_config,
 
                        channel_id: msg.temporary_channel_id,
                        channel_state: (ChannelState::OurInitSent as u32) | (ChannelState::TheirInitSent as u32),
-                       secp_ctx: Secp256k1::new(),
+                       secp_ctx,
 
                        latest_monitor_update_id: 0,
 
@@ -799,7 +820,6 @@ impl<Signer: Sign> Channel<Signer> {
 
                        funding_tx_confirmed_in: None,
                        short_channel_id: None,
-                       last_block_connected: Default::default(),
                        funding_tx_confirmations: 0,
 
                        feerate_per_kw: msg.feerate_per_kw,
@@ -813,6 +833,8 @@ impl<Signer: Sign> Channel<Signer> {
                        counterparty_max_accepted_htlcs: msg.max_accepted_htlcs,
                        minimum_depth: config.own_channel_config.minimum_depth,
 
+                       counterparty_forwarding_info: None,
+
                        channel_transaction_parameters: ChannelTransactionParameters {
                                holder_pubkeys: pubkeys,
                                holder_selected_contest_delay: config.own_channel_config.our_to_self_delay,
@@ -823,8 +845,9 @@ impl<Signer: Sign> Channel<Signer> {
                                }),
                                funding_outpoint: None
                        },
-                       counterparty_cur_commitment_point: Some(msg.first_per_commitment_point),
+                       funding_transaction: None,
 
+                       counterparty_cur_commitment_point: Some(msg.first_per_commitment_point),
                        counterparty_prev_commitment_point: None,
                        counterparty_node_id,
 
@@ -1516,7 +1539,7 @@ impl<Signer: Sign> Channel<Signer> {
                &self.get_counterparty_pubkeys().funding_pubkey
        }
 
-       pub fn funding_created<L: Deref>(&mut self, msg: &msgs::FundingCreated, logger: &L) -> Result<(msgs::FundingSigned, ChannelMonitor<Signer>), ChannelError> where L::Target: Logger {
+       pub fn funding_created<L: Deref>(&mut self, msg: &msgs::FundingCreated, last_block_hash: BlockHash, logger: &L) -> Result<(msgs::FundingSigned, ChannelMonitor<Signer>), ChannelError> where L::Target: Logger {
                if self.is_outbound() {
                        return Err(ChannelError::Close("Received funding_created for an outbound channel?".to_owned()));
                }
@@ -1564,13 +1587,13 @@ impl<Signer: Sign> Channel<Signer> {
                let funding_redeemscript = self.get_funding_redeemscript();
                let funding_txo_script = funding_redeemscript.to_v0_p2wsh();
                let obscure_factor = get_commitment_transaction_number_obscure_factor(&self.get_holder_pubkeys().payment_point, &self.get_counterparty_pubkeys().payment_point, self.is_outbound());
-               let mut channel_monitor = ChannelMonitor::new(self.holder_signer.clone(),
-                                                             &self.shutdown_pubkey, self.get_holder_selected_contest_delay(),
-                                                             &self.destination_script, (funding_txo, funding_txo_script.clone()),
-                                                             &self.channel_transaction_parameters,
-                                                             funding_redeemscript.clone(), self.channel_value_satoshis,
-                                                             obscure_factor,
-                                                             holder_commitment_tx);
+               let channel_monitor = ChannelMonitor::new(self.secp_ctx.clone(), self.holder_signer.clone(),
+                                                         &self.shutdown_pubkey, self.get_holder_selected_contest_delay(),
+                                                         &self.destination_script, (funding_txo, funding_txo_script.clone()),
+                                                         &self.channel_transaction_parameters,
+                                                         funding_redeemscript.clone(), self.channel_value_satoshis,
+                                                         obscure_factor,
+                                                         holder_commitment_tx, last_block_hash);
 
                channel_monitor.provide_latest_counterparty_commitment_tx(counterparty_initial_commitment_txid, Vec::new(), self.cur_counterparty_commitment_transaction_number, self.counterparty_cur_commitment_point.unwrap(), logger);
 
@@ -1587,7 +1610,7 @@ impl<Signer: Sign> Channel<Signer> {
 
        /// Handles a funding_signed message from the remote end.
        /// If this call is successful, broadcast the funding transaction (and not before!)
-       pub fn funding_signed<L: Deref>(&mut self, msg: &msgs::FundingSigned, logger: &L) -> Result<ChannelMonitor<Signer>, ChannelError> where L::Target: Logger {
+       pub fn funding_signed<L: Deref>(&mut self, msg: &msgs::FundingSigned, last_block_hash: BlockHash, logger: &L) -> Result<(ChannelMonitor<Signer>, Transaction), ChannelError> where L::Target: Logger {
                if !self.is_outbound() {
                        return Err(ChannelError::Close("Received funding_signed for an inbound channel?".to_owned()));
                }
@@ -1634,13 +1657,13 @@ impl<Signer: Sign> Channel<Signer> {
                let funding_txo = self.get_funding_txo().unwrap();
                let funding_txo_script = funding_redeemscript.to_v0_p2wsh();
                let obscure_factor = get_commitment_transaction_number_obscure_factor(&self.get_holder_pubkeys().payment_point, &self.get_counterparty_pubkeys().payment_point, self.is_outbound());
-               let mut channel_monitor = ChannelMonitor::new(self.holder_signer.clone(),
-                                                             &self.shutdown_pubkey, self.get_holder_selected_contest_delay(),
-                                                             &self.destination_script, (funding_txo, funding_txo_script),
-                                                             &self.channel_transaction_parameters,
-                                                             funding_redeemscript.clone(), self.channel_value_satoshis,
-                                                             obscure_factor,
-                                                             holder_commitment_tx);
+               let channel_monitor = ChannelMonitor::new(self.secp_ctx.clone(), self.holder_signer.clone(),
+                                                         &self.shutdown_pubkey, self.get_holder_selected_contest_delay(),
+                                                         &self.destination_script, (funding_txo, funding_txo_script),
+                                                         &self.channel_transaction_parameters,
+                                                         funding_redeemscript.clone(), self.channel_value_satoshis,
+                                                         obscure_factor,
+                                                         holder_commitment_tx, last_block_hash);
 
                channel_monitor.provide_latest_counterparty_commitment_tx(counterparty_initial_bitcoin_tx.txid, Vec::new(), self.cur_counterparty_commitment_transaction_number, self.counterparty_cur_commitment_point.unwrap(), logger);
 
@@ -1649,7 +1672,7 @@ impl<Signer: Sign> Channel<Signer> {
                self.cur_holder_commitment_transaction_number -= 1;
                self.cur_counterparty_commitment_transaction_number -= 1;
 
-               Ok(channel_monitor)
+               Ok((channel_monitor, self.funding_transaction.as_ref().cloned().unwrap()))
        }
 
        pub fn funding_locked(&mut self, msg: &msgs::FundingLocked) -> Result<(), ChannelError> {
@@ -2750,20 +2773,21 @@ impl<Signer: Sign> Channel<Signer> {
        /// Indicates that the latest ChannelMonitor update has been committed by the client
        /// successfully and we should restore normal operation. Returns messages which should be sent
        /// to the remote side.
-       pub fn monitor_updating_restored<L: Deref>(&mut self, logger: &L) -> (Option<msgs::RevokeAndACK>, Option<msgs::CommitmentUpdate>, RAACommitmentOrder, Vec<(PendingHTLCInfo, u64)>, Vec<(HTLCSource, PaymentHash, HTLCFailReason)>, bool, Option<msgs::FundingLocked>) where L::Target: Logger {
+       pub fn monitor_updating_restored<L: Deref>(&mut self, logger: &L) -> (Option<msgs::RevokeAndACK>, Option<msgs::CommitmentUpdate>, RAACommitmentOrder, Vec<(PendingHTLCInfo, u64)>, Vec<(HTLCSource, PaymentHash, HTLCFailReason)>, Option<Transaction>, Option<msgs::FundingLocked>) where L::Target: Logger {
                assert_eq!(self.channel_state & ChannelState::MonitorUpdateFailed as u32, ChannelState::MonitorUpdateFailed as u32);
                self.channel_state &= !(ChannelState::MonitorUpdateFailed as u32);
 
-               let needs_broadcast_safe = self.channel_state & (ChannelState::FundingSent as u32) != 0 && self.is_outbound();
+               let funding_broadcastable = if self.channel_state & (ChannelState::FundingSent as u32) != 0 && self.is_outbound() {
+                       self.funding_transaction.take()
+               } else { None };
 
-               // Because we will never generate a FundingBroadcastSafe event when we're in
-               // MonitorUpdateFailed, if we assume the user only broadcast the funding transaction when
-               // they received the FundingBroadcastSafe event, we can only ever hit
-               // monitor_pending_funding_locked when we're an inbound channel which failed to persist the
-               // monitor on funding_created, and we even got the funding transaction confirmed before the
-               // monitor was persisted.
+               // We will never broadcast the funding transaction when we're in MonitorUpdateFailed (and
+               // we assume the user never directly broadcasts the funding transaction and waits for us to
+               // do it). Thus, we can only ever hit monitor_pending_funding_locked when we're an inbound
+               // channel which failed to persist the monitor on funding_created, and we got the funding
+               // transaction confirmed before the monitor was persisted.
                let funding_locked = if self.monitor_pending_funding_locked {
-                       assert!(!self.is_outbound(), "Funding transaction broadcast without FundingBroadcastSafe!");
+                       assert!(!self.is_outbound(), "Funding transaction broadcast by the local client before it should have - LDK didn't do it!");
                        self.monitor_pending_funding_locked = false;
                        let next_per_commitment_point = self.holder_signer.get_per_commitment_point(self.cur_holder_commitment_transaction_number, &self.secp_ctx);
                        Some(msgs::FundingLocked {
@@ -2780,7 +2804,7 @@ impl<Signer: Sign> Channel<Signer> {
                if self.channel_state & (ChannelState::PeerDisconnected as u32) != 0 {
                        self.monitor_pending_revoke_and_ack = false;
                        self.monitor_pending_commitment_signed = false;
-                       return (None, None, RAACommitmentOrder::RevokeAndACKFirst, forwards, failures, needs_broadcast_safe, funding_locked);
+                       return (None, None, RAACommitmentOrder::RevokeAndACKFirst, forwards, failures, funding_broadcastable, funding_locked);
                }
 
                let raa = if self.monitor_pending_revoke_and_ack {
@@ -2794,11 +2818,11 @@ impl<Signer: Sign> Channel<Signer> {
                self.monitor_pending_commitment_signed = false;
                let order = self.resend_order.clone();
                log_trace!(logger, "Restored monitor updating resulting in {}{} commitment update and {} RAA, with {} first",
-                       if needs_broadcast_safe { "a funding broadcast safe, " } else { "" },
+                       if funding_broadcastable.is_some() { "a funding broadcastable, " } else { "" },
                        if commitment_update.is_some() { "a" } else { "no" },
                        if raa.is_some() { "an" } else { "no" },
                        match order { RAACommitmentOrder::CommitmentFirst => "commitment", RAACommitmentOrder::RevokeAndACKFirst => "RAA"});
-               (raa, commitment_update, order, forwards, failures, needs_broadcast_safe, funding_locked)
+               (raa, commitment_update, order, forwards, failures, funding_broadcastable, funding_locked)
        }
 
        pub fn update_fee<F: Deref>(&mut self, fee_estimator: &F, msg: &msgs::UpdateFee) -> Result<(), ChannelError>
@@ -3319,7 +3343,7 @@ impl<Signer: Sign> Channel<Signer> {
                        // Upper bound by capacity. We make it a bit less than full capacity to prevent attempts
                        // to use full capacity. This is an effort to reduce routing failures, because in many cases
                        // channel might have been used to route very small values (either by honest users or as DoS).
-                       self.channel_value_satoshis * 9 / 10,
+                       self.channel_value_satoshis * 1000 * 9 / 10,
 
                        Channel::<Signer>::get_holder_max_htlc_value_in_flight_msat(self.channel_value_satoshis)
                );
@@ -3338,6 +3362,10 @@ impl<Signer: Sign> Channel<Signer> {
                self.config.fee_proportional_millionths
        }
 
+       pub fn get_cltv_expiry_delta(&self) -> u16 {
+               cmp::max(self.config.cltv_expiry_delta, MIN_CLTV_EXPIRY_DELTA)
+       }
+
        #[cfg(test)]
        pub fn get_feerate(&self) -> u32 {
                self.feerate_per_kw
@@ -3511,12 +3539,12 @@ impl<Signer: Sign> Channel<Signer> {
                                _ => true
                        }
                });
-               let non_shutdown_state = self.channel_state & (!MULTI_STATE_FLAGS);
-               if header.block_hash() != self.last_block_connected {
-                       if self.funding_tx_confirmations > 0 {
-                               self.funding_tx_confirmations += 1;
-                       }
+
+               if self.funding_tx_confirmations > 0 {
+                       self.funding_tx_confirmations += 1;
                }
+
+               let non_shutdown_state = self.channel_state & (!MULTI_STATE_FLAGS);
                if non_shutdown_state & !(ChannelState::TheirFundingLocked as u32) == ChannelState::FundingSent as u32 {
                        for &(index_in_block, tx) in txdata.iter() {
                                let funding_txo = self.get_funding_txo().unwrap();
@@ -3550,58 +3578,53 @@ impl<Signer: Sign> Channel<Signer> {
                                                                }
                                                        }
                                                }
-                                               if height > 0xff_ff_ff || (index_in_block) > 0xff_ff_ff {
-                                                       panic!("Block was bogus - either height 16 million or had > 16 million transactions");
-                                               }
-                                               assert!(txo_idx <= 0xffff); // txo_idx is a (u16 as usize), so this is just listed here for completeness
                                                self.funding_tx_confirmations = 1;
-                                               self.short_channel_id = Some(((height as u64)         << (5*8)) |
-                                                                            ((index_in_block as u64) << (2*8)) |
-                                                                            ((txo_idx as u64)        << (0*8)));
+                                               self.short_channel_id = match scid_from_parts(height as u64, index_in_block as u64, txo_idx as u64) {
+                                                       Ok(scid) => Some(scid),
+                                                       Err(_) => panic!("Block was bogus - either height was > 16 million, had > 16 million transactions, or had > 65k outputs"),
+                                               }
                                        }
                                }
                        }
                }
-               if header.block_hash() != self.last_block_connected {
-                       self.last_block_connected = header.block_hash();
-                       self.update_time_counter = cmp::max(self.update_time_counter, header.time);
-                       if self.funding_tx_confirmations > 0 {
-                               if self.funding_tx_confirmations == self.minimum_depth as u64 {
-                                       let need_commitment_update = if non_shutdown_state == ChannelState::FundingSent as u32 {
-                                               self.channel_state |= ChannelState::OurFundingLocked as u32;
-                                               true
-                                       } else if non_shutdown_state == (ChannelState::FundingSent as u32 | ChannelState::TheirFundingLocked as u32) {
-                                               self.channel_state = ChannelState::ChannelFunded as u32 | (self.channel_state & MULTI_STATE_FLAGS);
-                                               self.update_time_counter += 1;
-                                               true
-                                       } else if non_shutdown_state == (ChannelState::FundingSent as u32 | ChannelState::OurFundingLocked as u32) {
-                                               // We got a reorg but not enough to trigger a force close, just update
-                                               // funding_tx_confirmed_in and return.
-                                               false
-                                       } else if self.channel_state < ChannelState::ChannelFunded as u32 {
-                                               panic!("Started confirming a channel in a state pre-FundingSent?: {}", self.channel_state);
+
+               self.update_time_counter = cmp::max(self.update_time_counter, header.time);
+               if self.funding_tx_confirmations > 0 {
+                       if self.funding_tx_confirmations == self.minimum_depth as u64 {
+                               let need_commitment_update = if non_shutdown_state == ChannelState::FundingSent as u32 {
+                                       self.channel_state |= ChannelState::OurFundingLocked as u32;
+                                       true
+                               } else if non_shutdown_state == (ChannelState::FundingSent as u32 | ChannelState::TheirFundingLocked as u32) {
+                                       self.channel_state = ChannelState::ChannelFunded as u32 | (self.channel_state & MULTI_STATE_FLAGS);
+                                       self.update_time_counter += 1;
+                                       true
+                               } else if non_shutdown_state == (ChannelState::FundingSent as u32 | ChannelState::OurFundingLocked as u32) {
+                                       // We got a reorg but not enough to trigger a force close, just update
+                                       // funding_tx_confirmed_in and return.
+                                       false
+                               } else if self.channel_state < ChannelState::ChannelFunded as u32 {
+                                       panic!("Started confirming a channel in a state pre-FundingSent?: {}", self.channel_state);
+                               } else {
+                                       // We got a reorg but not enough to trigger a force close, just update
+                                       // funding_tx_confirmed_in and return.
+                                       false
+                               };
+                               self.funding_tx_confirmed_in = Some(header.block_hash());
+
+                               //TODO: Note that this must be a duplicate of the previous commitment point they sent us,
+                               //as otherwise we will have a commitment transaction that they can't revoke (well, kinda,
+                               //they can by sending two revoke_and_acks back-to-back, but not really). This appears to be
+                               //a protocol oversight, but I assume I'm just missing something.
+                               if need_commitment_update {
+                                       if self.channel_state & (ChannelState::MonitorUpdateFailed as u32) == 0 {
+                                               let next_per_commitment_point = self.holder_signer.get_per_commitment_point(self.cur_holder_commitment_transaction_number, &self.secp_ctx);
+                                               return Ok((Some(msgs::FundingLocked {
+                                                       channel_id: self.channel_id,
+                                                       next_per_commitment_point,
+                                               }), timed_out_htlcs));
                                        } else {
-                                               // We got a reorg but not enough to trigger a force close, just update
-                                               // funding_tx_confirmed_in and return.
-                                               false
-                                       };
-                                       self.funding_tx_confirmed_in = Some(self.last_block_connected);
-
-                                       //TODO: Note that this must be a duplicate of the previous commitment point they sent us,
-                                       //as otherwise we will have a commitment transaction that they can't revoke (well, kinda,
-                                       //they can by sending two revoke_and_acks back-to-back, but not really). This appears to be
-                                       //a protocol oversight, but I assume I'm just missing something.
-                                       if need_commitment_update {
-                                               if self.channel_state & (ChannelState::MonitorUpdateFailed as u32) == 0 {
-                                                       let next_per_commitment_point = self.holder_signer.get_per_commitment_point(self.cur_holder_commitment_transaction_number, &self.secp_ctx);
-                                                       return Ok((Some(msgs::FundingLocked {
-                                                               channel_id: self.channel_id,
-                                                               next_per_commitment_point,
-                                                       }), timed_out_htlcs));
-                                               } else {
-                                                       self.monitor_pending_funding_locked = true;
-                                                       return Ok((None, timed_out_htlcs));
-                                               }
+                                               self.monitor_pending_funding_locked = true;
+                                               return Ok((None, timed_out_htlcs));
                                        }
                                }
                        }
@@ -3619,8 +3642,7 @@ impl<Signer: Sign> Channel<Signer> {
                                return true;
                        }
                }
-               self.last_block_connected = header.block_hash();
-               if Some(self.last_block_connected) == self.funding_tx_confirmed_in {
+               if Some(header.block_hash()) == self.funding_tx_confirmed_in {
                        self.funding_tx_confirmations = self.minimum_depth as u64 - 1;
                }
                false
@@ -3715,7 +3737,7 @@ impl<Signer: Sign> Channel<Signer> {
        /// Note that channel_id changes during this call!
        /// Do NOT broadcast the funding transaction until after a successful funding_signed call!
        /// If an Err is returned, it is a ChannelError::Close.
-       pub fn get_outbound_funding_created<L: Deref>(&mut self, funding_txo: OutPoint, logger: &L) -> Result<msgs::FundingCreated, ChannelError> where L::Target: Logger {
+       pub fn get_outbound_funding_created<L: Deref>(&mut self, funding_transaction: Transaction, funding_txo: OutPoint, logger: &L) -> Result<msgs::FundingCreated, ChannelError> where L::Target: Logger {
                if !self.is_outbound() {
                        panic!("Tried to create outbound funding_created message on an inbound channel!");
                }
@@ -3746,6 +3768,7 @@ impl<Signer: Sign> Channel<Signer> {
 
                self.channel_state = ChannelState::FundingCreated as u32;
                self.channel_id = funding_txo.to_channel_id();
+               self.funding_transaction = Some(funding_transaction);
 
                Ok(msgs::FundingCreated {
                        temporary_channel_id,
@@ -4081,7 +4104,8 @@ impl<Signer: Sign> Channel<Signer> {
                        signature = res.0;
                        htlc_signatures = res.1;
 
-                       log_trace!(logger, "Signed remote commitment tx {} with redeemscript {} -> {}",
+                       log_trace!(logger, "Signed remote commitment tx {} (txid {}) with redeemscript {} -> {}",
+                               encode::serialize_hex(&counterparty_commitment_tx.0.trust().built_transaction().transaction),
                                &counterparty_commitment_txid,
                                encode::serialize_hex(&self.get_funding_redeemscript()),
                                log_bytes!(signature.serialize_compact()[..]));
@@ -4116,6 +4140,25 @@ impl<Signer: Sign> Channel<Signer> {
                }
        }
 
+       /// Get forwarding information for the counterparty.
+       pub fn counterparty_forwarding_info(&self) -> Option<CounterpartyForwardingInfo> {
+               self.counterparty_forwarding_info.clone()
+       }
+
+       pub fn channel_update(&mut self, msg: &msgs::ChannelUpdate) -> Result<(), ChannelError> {
+               let usable_channel_value_msat = (self.channel_value_satoshis - self.counterparty_selected_channel_reserve_satoshis) * 1000;
+               if msg.contents.htlc_minimum_msat >= usable_channel_value_msat {
+                       return Err(ChannelError::Close("Minimum htlc value is greater than channel value".to_string()));
+               }
+               self.counterparty_forwarding_info = Some(CounterpartyForwardingInfo {
+                       fee_base_msat: msg.contents.fee_base_msat,
+                       fee_proportional_millionths: msg.contents.fee_proportional_millionths,
+                       cltv_expiry_delta: msg.contents.cltv_expiry_delta
+               });
+
+               Ok(())
+       }
+
        /// Begins the shutdown process, getting a message for the remote peer and returning all
        /// holding cell HTLCs for payment failure.
        pub fn get_shutdown(&mut self) -> Result<(msgs::Shutdown, Vec<(HTLCSource, PaymentHash)>), APIError> {
@@ -4172,7 +4215,11 @@ impl<Signer: Sign> Channel<Signer> {
        /// those explicitly stated to be allowed after shutdown completes, eg some simple getters).
        /// Also returns the list of payment_hashes for channels which we can safely fail backwards
        /// immediately (others we will have to allow to time out).
-       pub fn force_shutdown(&mut self, should_broadcast: bool) -> (Option<OutPoint>, ChannelMonitorUpdate, Vec<(HTLCSource, PaymentHash)>) {
+       pub fn force_shutdown(&mut self, should_broadcast: bool) -> (Option<(OutPoint, ChannelMonitorUpdate)>, Vec<(HTLCSource, PaymentHash)>) {
+               // Note that we MUST only generate a monitor update that indicates force-closure - we're
+               // called during initialization prior to the chain_monitor in the encompassing ChannelManager
+               // being fully configured in some cases. Thus, its likely any monitor events we generate will
+               // be delayed in being processed! See the docs for `ChannelManagerReadArgs` for more.
                assert!(self.channel_state != ChannelState::ShutdownComplete as u32);
 
                // We go ahead and "free" any holding cell HTLCs or HTLCs we haven't yet committed to and
@@ -4186,7 +4233,7 @@ impl<Signer: Sign> Channel<Signer> {
                                _ => {}
                        }
                }
-               let funding_txo = if let Some(funding_txo) = self.get_funding_txo() {
+               let monitor_update = if let Some(funding_txo) = self.get_funding_txo() {
                        // If we haven't yet exchanged funding signatures (ie channel_state < FundingSent),
                        // returning a channel monitor update here would imply a channel monitor update before
                        // we even registered the channel monitor to begin with, which is invalid.
@@ -4195,17 +4242,17 @@ impl<Signer: Sign> Channel<Signer> {
                        // monitor update to the user, even if we return one).
                        // See test_duplicate_chan_id and test_pre_lockin_no_chan_closed_update for more.
                        if self.channel_state & (ChannelState::FundingSent as u32 | ChannelState::ChannelFunded as u32 | ChannelState::ShutdownComplete as u32) != 0 {
-                               Some(funding_txo.clone())
+                               self.latest_monitor_update_id += 1;
+                               Some((funding_txo, ChannelMonitorUpdate {
+                                       update_id: self.latest_monitor_update_id,
+                                       updates: vec![ChannelMonitorUpdateStep::ChannelForceClosed { should_broadcast }],
+                               }))
                        } else { None }
                } else { None };
 
                self.channel_state = ChannelState::ShutdownComplete as u32;
                self.update_time_counter += 1;
-               self.latest_monitor_update_id += 1;
-               (funding_txo, ChannelMonitorUpdate {
-                       update_id: self.latest_monitor_update_id,
-                       updates: vec![ChannelMonitorUpdateStep::ChannelForceClosed { should_broadcast }],
-               }, dropped_outbound_htlcs)
+               (monitor_update, dropped_outbound_htlcs)
        }
 }
 
@@ -4424,8 +4471,6 @@ impl<Signer: Sign> Writeable for Channel<Signer> {
 
                self.funding_tx_confirmed_in.write(writer)?;
                self.short_channel_id.write(writer)?;
-
-               self.last_block_connected.write(writer)?;
                self.funding_tx_confirmations.write(writer)?;
 
                self.counterparty_dust_limit_satoshis.write(writer)?;
@@ -4437,9 +4482,20 @@ impl<Signer: Sign> Writeable for Channel<Signer> {
                self.counterparty_max_accepted_htlcs.write(writer)?;
                self.minimum_depth.write(writer)?;
 
+               match &self.counterparty_forwarding_info {
+                       Some(info) => {
+                               1u8.write(writer)?;
+                               info.fee_base_msat.write(writer)?;
+                               info.fee_proportional_millionths.write(writer)?;
+                               info.cltv_expiry_delta.write(writer)?;
+                       },
+                       None => 0u8.write(writer)?
+               }
+
                self.channel_transaction_parameters.write(writer)?;
-               self.counterparty_cur_commitment_point.write(writer)?;
+               self.funding_transaction.write(writer)?;
 
+               self.counterparty_cur_commitment_point.write(writer)?;
                self.counterparty_prev_commitment_point.write(writer)?;
                self.counterparty_node_id.write(writer)?;
 
@@ -4586,8 +4642,6 @@ impl<'a, Signer: Sign, K: Deref> ReadableArgs<&'a K> for Channel<Signer>
 
                let funding_tx_confirmed_in = Readable::read(reader)?;
                let short_channel_id = Readable::read(reader)?;
-
-               let last_block_connected = Readable::read(reader)?;
                let funding_tx_confirmations = Readable::read(reader)?;
 
                let counterparty_dust_limit_satoshis = Readable::read(reader)?;
@@ -4599,7 +4653,19 @@ impl<'a, Signer: Sign, K: Deref> ReadableArgs<&'a K> for Channel<Signer>
                let counterparty_max_accepted_htlcs = Readable::read(reader)?;
                let minimum_depth = Readable::read(reader)?;
 
+               let counterparty_forwarding_info = match <u8 as Readable>::read(reader)? {
+                       0 => None,
+                       1 => Some(CounterpartyForwardingInfo {
+                               fee_base_msat: Readable::read(reader)?,
+                               fee_proportional_millionths: Readable::read(reader)?,
+                               cltv_expiry_delta: Readable::read(reader)?,
+                       }),
+                       _ => return Err(DecodeError::InvalidValue),
+               };
+
                let channel_parameters = Readable::read(reader)?;
+               let funding_transaction = Readable::read(reader)?;
+
                let counterparty_cur_commitment_point = Readable::read(reader)?;
 
                let counterparty_prev_commitment_point = Readable::read(reader)?;
@@ -4608,13 +4674,16 @@ impl<'a, Signer: Sign, K: Deref> ReadableArgs<&'a K> for Channel<Signer>
                let counterparty_shutdown_scriptpubkey = Readable::read(reader)?;
                let commitment_secrets = Readable::read(reader)?;
 
+               let mut secp_ctx = Secp256k1::new();
+               secp_ctx.seeded_randomize(&keys_source.get_secure_random_bytes());
+
                Ok(Channel {
                        user_id,
 
                        config,
                        channel_id,
                        channel_state,
-                       secp_ctx: Secp256k1::new(),
+                       secp_ctx,
                        channel_value_satoshis,
 
                        latest_monitor_update_id,
@@ -4655,7 +4724,6 @@ impl<'a, Signer: Sign, K: Deref> ReadableArgs<&'a K> for Channel<Signer>
 
                        funding_tx_confirmed_in,
                        short_channel_id,
-                       last_block_connected,
                        funding_tx_confirmations,
 
                        counterparty_dust_limit_satoshis,
@@ -4667,9 +4735,12 @@ impl<'a, Signer: Sign, K: Deref> ReadableArgs<&'a K> for Channel<Signer>
                        counterparty_max_accepted_htlcs,
                        minimum_depth,
 
+                       counterparty_forwarding_info,
+
                        channel_transaction_parameters: channel_parameters,
-                       counterparty_cur_commitment_point,
+                       funding_transaction,
 
+                       counterparty_cur_commitment_point,
                        counterparty_prev_commitment_point,
                        counterparty_node_id,
 
@@ -4702,7 +4773,7 @@ mod tests {
        use ln::channel::{Channel,Sign,InboundHTLCOutput,OutboundHTLCOutput,InboundHTLCState,OutboundHTLCState,HTLCOutputInCommitment,HTLCCandidate,HTLCInitiator,TxCreationKeys};
        use ln::channel::MAX_FUNDING_SATOSHIS;
        use ln::features::InitFeatures;
-       use ln::msgs::{OptionalField, DataLossProtect, DecodeError};
+       use ln::msgs::{ChannelUpdate, DataLossProtect, DecodeError, OptionalField, UnsignedChannelUpdate};
        use ln::chan_utils;
        use ln::chan_utils::{ChannelPublicKeys, HolderCommitmentTransaction, CounterpartyChannelTransactionParameters, HTLC_SUCCESS_TX_WEIGHT, HTLC_TIMEOUT_TX_WEIGHT};
        use chain::chaininterface::{FeeEstimator,ConfirmationTarget};
@@ -4713,6 +4784,7 @@ mod tests {
        use util::test_utils;
        use util::logger::Logger;
        use bitcoin::secp256k1::{Secp256k1, Message, Signature, All};
+       use bitcoin::secp256k1::ffi::Signature as FFISignature;
        use bitcoin::secp256k1::key::{SecretKey,PublicKey};
        use bitcoin::hashes::sha256::Hash as Sha256;
        use bitcoin::hashes::Hash;
@@ -4910,6 +4982,8 @@ mod tests {
                let secp_ctx = Secp256k1::new();
                let seed = [42; 32];
                let network = Network::Testnet;
+               let chain_hash = genesis_block(network).header.block_hash();
+               let last_block_hash = chain_hash;
                let keys_provider = test_utils::TestKeysInterface::new(&seed, network);
 
                // Go through the flow of opening a channel between two nodes.
@@ -4920,7 +4994,7 @@ mod tests {
                let mut node_a_chan = Channel::<EnforcingSigner>::new_outbound(&&feeest, &&keys_provider, node_b_node_id, 10000000, 100000, 42, &config).unwrap();
 
                // Create Node B's channel by receiving Node A's open_channel message
-               let open_channel_msg = node_a_chan.get_open_channel(genesis_block(network).header.block_hash());
+               let open_channel_msg = node_a_chan.get_open_channel(chain_hash);
                let node_b_node_id = PublicKey::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[7; 32]).unwrap());
                let mut node_b_chan = Channel::<EnforcingSigner>::new_from_req(&&feeest, &&keys_provider, node_b_node_id, InitFeatures::known(), &open_channel_msg, 7, &config).unwrap();
 
@@ -4934,11 +5008,11 @@ mod tests {
                        value: 10000000, script_pubkey: output_script.clone(),
                }]};
                let funding_outpoint = OutPoint{ txid: tx.txid(), index: 0 };
-               let funding_created_msg = node_a_chan.get_outbound_funding_created(funding_outpoint, &&logger).unwrap();
-               let (funding_signed_msg, _) = node_b_chan.funding_created(&funding_created_msg, &&logger).unwrap();
+               let funding_created_msg = node_a_chan.get_outbound_funding_created(tx.clone(), funding_outpoint, &&logger).unwrap();
+               let (funding_signed_msg, _) = node_b_chan.funding_created(&funding_created_msg, last_block_hash, &&logger).unwrap();
 
                // Node B --> Node A: funding signed
-               let _ = node_a_chan.funding_signed(&funding_signed_msg, &&logger);
+               let _ = node_a_chan.funding_signed(&funding_signed_msg, last_block_hash, &&logger);
 
                // Now disconnect the two nodes and check that the commitment point in
                // Node B's channel_reestablish message is sane.
@@ -4967,6 +5041,54 @@ mod tests {
                }
        }
 
+       #[test]
+       fn channel_update() {
+               let feeest = TestFeeEstimator{fee_est: 15000};
+               let secp_ctx = Secp256k1::new();
+               let seed = [42; 32];
+               let network = Network::Testnet;
+               let chain_hash = genesis_block(network).header.block_hash();
+               let keys_provider = test_utils::TestKeysInterface::new(&seed, network);
+
+               // Create a channel.
+               let node_b_node_id = PublicKey::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[42; 32]).unwrap());
+               let config = UserConfig::default();
+               let mut node_a_chan = Channel::<EnforcingSigner>::new_outbound(&&feeest, &&keys_provider, node_b_node_id, 10000000, 100000, 42, &config).unwrap();
+               assert!(node_a_chan.counterparty_forwarding_info.is_none());
+               assert_eq!(node_a_chan.holder_htlc_minimum_msat, 1); // the default
+               assert!(node_a_chan.counterparty_forwarding_info().is_none());
+
+               // Make sure that receiving a channel update will update the Channel as expected.
+               let update = ChannelUpdate {
+                       contents: UnsignedChannelUpdate {
+                               chain_hash,
+                               short_channel_id: 0,
+                               timestamp: 0,
+                               flags: 0,
+                               cltv_expiry_delta: 100,
+                               htlc_minimum_msat: 5,
+                               htlc_maximum_msat: OptionalField::Absent,
+                               fee_base_msat: 110,
+                               fee_proportional_millionths: 11,
+                               excess_data: Vec::new(),
+                       },
+                       signature: Signature::from(unsafe { FFISignature::new() })
+               };
+               node_a_chan.channel_update(&update).unwrap();
+
+               // The counterparty can send an update with a higher minimum HTLC, but that shouldn't
+               // change our official htlc_minimum_msat.
+               assert_eq!(node_a_chan.holder_htlc_minimum_msat, 1);
+               match node_a_chan.counterparty_forwarding_info() {
+                       Some(info) => {
+                               assert_eq!(info.cltv_expiry_delta, 100);
+                               assert_eq!(info.fee_base_msat, 110);
+                               assert_eq!(info.fee_proportional_millionths, 11);
+                       },
+                       None => panic!("expected counterparty forwarding info to be Some")
+               }
+       }
+
        #[test]
        fn outbound_commitment_test() {
                // Test vectors from BOLT 3 Appendix C: