X-Git-Url: http://git.bitcoin.ninja/index.cgi?a=blobdiff_plain;f=src%2Fln%2Fchannel.rs;h=26a3d2061be644cd90292ca680577830fe559b2c;hb=1228663b3e04765c6f8a243d76a1c09ef1d926bc;hp=6c6dacc84c3821c2285b0156a62498dc068b6a49;hpb=ab56b81acd9da3a697dfc37fc4cb43cd8fbb1a2c;p=rust-lightning

diff --git a/src/ln/channel.rs b/src/ln/channel.rs
index 6c6dacc8..26a3d206 100644
--- a/src/ln/channel.rs
+++ b/src/ln/channel.rs
@@ -17,15 +17,16 @@ use crypto::hkdf::{hkdf_extract,hkdf_expand};
 use ln::msgs;
 use ln::msgs::{HandleError, MsgEncodable};
 use ln::channelmonitor::ChannelMonitor;
-use ln::channelmanager::PendingForwardHTLCInfo;
-use ln::chan_utils::{TxCreationKeys,HTLCOutputInCommitment};
+use ln::channelmanager::{PendingForwardHTLCInfo, HTLCFailReason};
+use ln::chan_utils::{TxCreationKeys,HTLCOutputInCommitment,HTLC_SUCCESS_TX_WEIGHT,HTLC_TIMEOUT_TX_WEIGHT};
 use ln::chan_utils;
 use chain::chaininterface::{FeeEstimator,ConfirmationTarget};
+use chain::transaction::OutPoint;
 use util::{transaction_utils,rng};
 use util::sha2::Sha256;
 
 use std::default::Default;
-use std::cmp;
+use std::{cmp,mem};
 use std::time::Instant;
 
 pub struct ChannelKeys {
@@ -43,7 +44,7 @@ impl ChannelKeys {
 	pub fn new_from_seed(seed: &[u8; 32]) -> Result<ChannelKeys, secp256k1::Error> {
 		let mut prk = [0; 32];
 		hkdf_extract(Sha256::new(), b"rust-lightning key gen salt", seed, &mut prk);
-		let secp_ctx = Secp256k1::new();
+		let secp_ctx = Secp256k1::without_caps();
 
 		let mut okm = [0; 32];
 		hkdf_expand(Sha256::new(), &prk, b"rust-lightning funding key info", &mut okm);
@@ -84,19 +85,73 @@ impl ChannelKeys {
 
 #[derive(PartialEq)]
 enum HTLCState {
+	/// Added by remote, to be included in next local commitment tx.
 	RemoteAnnounced,
+	/// Included in a received commitment_signed message (implying we've revoke_and_ack'ed it), but
+	/// the remote side hasn't yet revoked their previous state, which we need them to do before we
+	/// accept this HTLC. Implies AwaitingRemoteRevoke.
+	/// We also have not yet included this HTLC in a commitment_signed message, and are waiting on
+	/// a remote revoke_and_ack on a previous state before we can do so.
+	AwaitingRemoteRevokeToAnnounce,
+	/// Included in a received commitment_signed message (implying we've revoke_and_ack'ed it), but
+	/// the remote side hasn't yet revoked their previous state, which we need them to do before we
+	/// accept this HTLC. Implies AwaitingRemoteRevoke.
+	/// We have included this HTLC in our latest commitment_signed and are now just waiting on a
+	/// revoke_and_ack.
+	AwaitingAnnouncedRemoteRevoke,
+	/// Added by us and included in a commitment_signed (if we were AwaitingRemoteRevoke when we
+	/// created it we would have put it in the holding cell instead). When they next revoke_and_ack
+	/// we will promote to Committed (note that they may not accept it until the next time we
+	/// revoke, but we dont really care about that:
+	///  * they've revoked, so worst case we can announce an old state and get our (option on)
+	///    money back (though we wont), and,
+	///  * we'll send them a revoke when they send a commitment_signed, and since only they're
+	///    allowed to remove it, the "can only be removed once committed on both sides" requirement
+	///    doesn't matter to us and its up to them to enforce it, worst-case they jump ahead but
+	///    we'll never get out of sync).
 	LocalAnnounced,
 	Committed,
+	/// Remote removed this (outbound) HTLC. We're waiting on their commitment_signed to finalize
+	/// the change (though they'll need to revoke before we fail the payment).
+	RemoteRemoved,
+	/// Remote removed this and sent a commitment_signed (implying we've revoke_and_ack'ed it), but
+	/// the remote side hasn't yet revoked their previous state, which we need them to do before we
+	/// can do any backwards failing. Implies AwaitingRemoteRevoke.
+	/// We also have not yet removed this HTLC in a commitment_signed message, and are waiting on a
+	/// remote revoke_and_ack on a previous state before we can do so.
+	AwaitingRemoteRevokeToRemove,
+	/// Remote removed this and sent a commitment_signed (implying we've revoke_and_ack'ed it), but
+	/// the remote side hasn't yet revoked their previous state, which we need them to do before we
+	/// can do any backwards failing. Implies AwaitingRemoteRevoke.
+	/// We have removed this HTLC in our latest commitment_signed and are now just waiting on a
+	/// revoke_and_ack to drop completely.
+	AwaitingRemovedRemoteRevoke,
+	/// Removed by us and a new commitment_signed was sent (if we were AwaitingRemoteRevoke when we
+	/// created it we would have put it in the holding cell instead). When they next revoke_and_ack
+	/// we'll promote to LocalRemovedAwaitingCommitment if we fulfilled, otherwise we'll drop at
+	/// that point.
+	/// Note that we have to keep an eye on the HTLC until we've received a broadcastable
+	/// commitment transaction without it as otherwise we'll have to force-close the channel to
+	/// claim it before the timeout (obviously doesn't apply to revoked HTLCs that we can't claim
+	/// anyway).
+	LocalRemoved,
+	/// Removed by us, sent a new commitment_signed and got a revoke_and_ack. Just waiting on an
+	/// updated local commitment transaction.
+	LocalRemovedAwaitingCommitment,
 }
 
-struct HTLCOutput {
+struct HTLCOutput { //TODO: Refactor into Outbound/InboundHTLCOutput (will save memory and fewer panics)
 	outbound: bool, // ie to an HTLC-Timeout transaction
 	htlc_id: u64,
 	amount_msat: u64,
 	cltv_expiry: u32,
 	payment_hash: [u8; 32],
 	state: HTLCState,
-	// state == RemoteAnnounced implies pending_forward_state, otherwise it must be None
+	/// If we're in a Remote* removed state, set if they failed, otherwise None
+	fail_reason: Option<HTLCFailReason>,
+	/// If we're in LocalRemoved*, set to true if we fulfilled the HTLC, and can claim money
+	local_removed_fulfilled: bool,
+	/// state pre-committed Remote* implies pending_forward_state, otherwise it must be None
 	pending_forward_state: Option<PendingForwardHTLCInfo>,
 }
 
@@ -113,13 +168,23 @@ impl HTLCOutput {
 }
 
 /// See AwaitingRemoteRevoke ChannelState for more info
-struct HTLCOutputAwaitingACK {
-	// always outbound
-	amount_msat: u64,
-	cltv_expiry: u32,
-	payment_hash: [u8; 32],
-	onion_routing_packet: msgs::OnionPacket,
-	time_created: Instant, //TODO: Some kind of timeout thing-a-majig
+enum HTLCUpdateAwaitingACK {
+	AddHTLC {
+		// always outbound
+		amount_msat: u64,
+		cltv_expiry: u32,
+		payment_hash: [u8; 32],
+		onion_routing_packet: msgs::OnionPacket,
+		time_created: Instant, //TODO: Some kind of timeout thing-a-majig
+	},
+	ClaimHTLC {
+		payment_preimage: [u8; 32],
+		payment_hash: [u8; 32], // Only here for effecient duplicate detection
+	},
+	FailHTLC {
+		payment_hash: [u8; 32],
+		err_packet: msgs::OnionErrorPacket,
+	},
 }
 
 enum ChannelState {
@@ -149,7 +214,20 @@ enum ChannelState {
 	/// later.
 	/// Flag is set on ChannelFunded.
 	AwaitingRemoteRevoke = (1 << 7),
+	/// Flag which is set on ChannelFunded or FundingSent after receiving a shutdown message from
+	/// the remote end. If set, they may not add any new HTLCs to the channel, and we are expected
+	/// to respond with our own shutdown message when possible.
+	RemoteShutdownSent = (1 << 8),
+	/// Flag which is set on ChannelFunded or FundingSent after sending a shutdown message. At this
+	/// point, we may not add any new HTLCs to the channel.
+	/// TODO: Investigate some kind of timeout mechanism by which point the remote end must provide
+	/// us their shutdown.
+	LocalShutdownSent = (1 << 9),
+	/// We've successfully negotiated a closing_signed dance. At this point ChannelManager is about
+	/// to drop us, but we store this anyway.
+	ShutdownComplete = (1 << 10),
 }
+const BOTH_SIDES_SHUTDOWN_MASK: u32 = (ChannelState::LocalShutdownSent as u32 | ChannelState::RemoteShutdownSent as u32);
 
 // 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
@@ -171,12 +249,20 @@ pub struct Channel {
 	cur_remote_commitment_transaction_number: u64,
 	value_to_self_msat: u64, // Excluding all pending_htlcs, excluding fees
 	pending_htlcs: Vec<HTLCOutput>,
-	holding_cell_htlcs: Vec<HTLCOutputAwaitingACK>,
+	holding_cell_htlc_updates: Vec<HTLCUpdateAwaitingACK>,
 	next_local_htlc_id: u64,
 	next_remote_htlc_id: u64,
 	channel_update_count: u32,
 	feerate_per_kw: u64,
 
+	#[cfg(test)]
+	// Used in ChannelManager's tests to send a revoked transaction
+	pub last_local_commitment_txn: Vec<Transaction>,
+	#[cfg(not(test))]
+	last_local_commitment_txn: Vec<Transaction>,
+
+	last_sent_closing_fee: Option<(u64, u64)>, // (feerate, fee)
+
 	/// The hash of the block in which the funding transaction reached our CONF_TARGET. We use this
 	/// to detect unconfirmation after a serialize-unserialize roudtrip where we may not see a full
 	/// series of block_connected/block_disconnected calls. Obviously this is not a guarantee as we
@@ -206,12 +292,16 @@ pub struct Channel {
 	their_delayed_payment_basepoint: PublicKey,
 	their_htlc_basepoint: PublicKey,
 	their_cur_commitment_point: PublicKey,
+
+	their_prev_commitment_point: Option<PublicKey>,
 	their_node_id: PublicKey,
 
+	their_shutdown_scriptpubkey: Option<Script>,
+
 	channel_monitor: ChannelMonitor,
 }
 
-const OUR_MAX_HTLCS: u16 = 1; //TODO
+const OUR_MAX_HTLCS: u16 = 5; //TODO
 const CONF_TARGET: u32 = 12; //TODO: Should be much higher
 /// Confirmation count threshold at which we close a channel. Ideally we'd keep the channel around
 /// on ice until the funding transaction gets more confirmations, but the LN protocol doesn't
@@ -224,27 +314,24 @@ const BREAKDOWN_TIMEOUT: u16 = 6 * 24 * 7; //TODO?
 const MAX_LOCAL_BREAKDOWN_TIMEOUT: u16 = 6 * 24 * 14;
 const COMMITMENT_TX_BASE_WEIGHT: u64 = 724;
 const COMMITMENT_TX_WEIGHT_PER_HTLC: u64 = 172;
-const HTLC_SUCCESS_TX_WEIGHT: u64 = 703;
-const HTLC_TIMEOUT_TX_WEIGHT: u64 = 663;
 const SPENDING_INPUT_FOR_A_OUTPUT_WEIGHT: u64 = 79; // prevout: 36, nSequence: 4, script len: 1, witness lengths: (3+1)/4, sig: 73/4, if-selector: 1, redeemScript: (6 ops + 2*33 pubkeys + 1*2 delay)/4
 const B_OUTPUT_PLUS_SPENDING_INPUT_WEIGHT: u64 = 104; // prevout: 40, nSequence: 4, script len: 1, witness lengths: 3/4, sig: 73/4, pubkey: 33/4, output: 31 (TODO: Wrong? Useless?)
 
 macro_rules! secp_call {
-	( $res : expr ) => {
+	( $res: expr, $err: expr ) => {
 		match $res {
 			Ok(key) => key,
 			//TODO: make the error a parameter
-			Err(_) => return Err(HandleError{err: "Secp call failed - probably bad signature or evil data generated a bad pubkey/privkey", msg: None})
+			Err(_) => return Err(HandleError{err: $err, msg: Some(msgs::ErrorAction::DisconnectPeer{})})
 		}
 	};
 }
 
-macro_rules! get_key {
-	( $ctx : expr, $slice : expr ) => {
-		secp_call! (SecretKey::from_slice($ctx, $slice))
-	};
+macro_rules! secp_derived_key {
+	( $res: expr ) => {
+		secp_call!($res, "Derived invalid key, peer is maliciously selecting parameters")
+	}
 }
-
 impl Channel {
 	// Convert constants + channel value to limits:
 	fn get_our_max_htlc_value_in_flight_msat(channel_value_satoshis: u64) -> u64 {
@@ -267,7 +354,7 @@ impl Channel {
 	// Constructors:
 
 	/// panics if channel_value_satoshis is >= (1 << 24)
-	pub fn new_outbound(fee_estimator: &FeeEstimator, their_node_id: PublicKey, channel_value_satoshis: u64, announce_publicly: bool, user_id: u64) -> Channel {
+	pub fn new_outbound(fee_estimator: &FeeEstimator, chan_keys: ChannelKeys, their_node_id: PublicKey, channel_value_satoshis: u64, announce_publicly: bool, user_id: u64) -> Channel {
 		if channel_value_satoshis >= (1 << 24) {
 			panic!("funding value > 2^24");
 		}
@@ -275,19 +362,12 @@ impl Channel {
 		let feerate = fee_estimator.get_est_sat_per_vbyte(ConfirmationTarget::Normal);
 		let background_feerate = fee_estimator.get_est_sat_per_vbyte(ConfirmationTarget::Background);
 
-		let mut key_seed = [0u8; 32];
-		rng::fill_bytes(&mut key_seed);
-		let chan_keys = match ChannelKeys::new_from_seed(&key_seed) {
-			Ok(key) => key,
-			Err(_) => panic!("RNG is busted!")
-		};
-
 		let secp_ctx = Secp256k1::new();
 		let our_channel_monitor_claim_key_hash = Hash160::from_data(&PublicKey::from_secret_key(&secp_ctx, &chan_keys.channel_monitor_claim_key).unwrap().serialize());
 		let our_channel_monitor_claim_script = Builder::new().push_opcode(opcodes::All::OP_PUSHBYTES_0).push_slice(&our_channel_monitor_claim_key_hash[..]).into_script();
 		let channel_monitor = ChannelMonitor::new(&chan_keys.revocation_base_key,
 		                                          &PublicKey::from_secret_key(&secp_ctx, &chan_keys.delayed_payment_base_key).unwrap(),
-		                                          &PublicKey::from_secret_key(&secp_ctx, &chan_keys.htlc_base_key).unwrap(),
+		                                          &chan_keys.htlc_base_key,
 		                                          BREAKDOWN_TIMEOUT, our_channel_monitor_claim_script);
 
 		Channel {
@@ -305,10 +385,14 @@ impl Channel {
 			cur_remote_commitment_transaction_number: (1 << 48) - 1,
 			value_to_self_msat: channel_value_satoshis * 1000, //TODO: give them something on open? Parameterize it?
 			pending_htlcs: Vec::new(),
-			holding_cell_htlcs: Vec::new(),
+			holding_cell_htlc_updates: Vec::new(),
 			next_local_htlc_id: 0,
 			next_remote_htlc_id: 0,
-			channel_update_count: 0,
+			channel_update_count: 1,
+
+			last_local_commitment_txn: Vec::new(),
+
+			last_sent_closing_fee: None,
 
 			funding_tx_confirmed_in: Default::default(),
 			short_channel_id: None,
@@ -331,56 +415,62 @@ impl Channel {
 			their_delayed_payment_basepoint: PublicKey::new(),
 			their_htlc_basepoint: PublicKey::new(),
 			their_cur_commitment_point: PublicKey::new(),
+
+			their_prev_commitment_point: None,
 			their_node_id: their_node_id,
 
+			their_shutdown_scriptpubkey: None,
+
 			channel_monitor: channel_monitor,
 		}
 	}
 
 	fn check_remote_fee(fee_estimator: &FeeEstimator, feerate_per_kw: u32) -> Result<(), HandleError> {
 		if (feerate_per_kw as u64) < fee_estimator.get_est_sat_per_vbyte(ConfirmationTarget::Background) * 250 {
-			return Err(HandleError{err: "Peer's feerate much too low", msg: None});
+			return Err(HandleError{err: "Peer's feerate much too low", msg: Some(msgs::ErrorAction::DisconnectPeer{})});
 		}
 		if (feerate_per_kw as u64) > fee_estimator.get_est_sat_per_vbyte(ConfirmationTarget::HighPriority) * 375 { // 375 = 250 * 1.5x
-			return Err(HandleError{err: "Peer's feerate much too high", msg: None});
+			return Err(HandleError{err: "Peer's feerate much too high", msg: Some(msgs::ErrorAction::DisconnectPeer{})});
 		}
 		Ok(())
 	}
 
 	/// Creates a new channel from a remote sides' request for one.
 	/// Assumes chain_hash has already been checked and corresponds with what we expect!
-	pub fn new_from_req(fee_estimator: &FeeEstimator, their_node_id: PublicKey, msg: &msgs::OpenChannel, user_id: u64, announce_publicly: bool) -> Result<Channel, HandleError> {
+	/// Generally prefers to take the DisconnectPeer action on failure, as a notice to the sender
+	/// that we're rejecting the new channel.
+	pub fn new_from_req(fee_estimator: &FeeEstimator, chan_keys: ChannelKeys, their_node_id: PublicKey, msg: &msgs::OpenChannel, user_id: u64, announce_publicly: bool) -> Result<Channel, HandleError> {
 		// Check sanity of message fields:
 		if msg.funding_satoshis >= (1 << 24) {
-			return Err(HandleError{err: "funding value > 2^24", msg: None});
+			return Err(HandleError{err: "funding value > 2^24", msg: Some(msgs::ErrorAction::DisconnectPeer{})});
 		}
 		if msg.funding_satoshis > 21000000 * 100000000 {
-			return Err(HandleError{err: "More funding_satoshis than there are satoshis!", msg: None});
+			return Err(HandleError{err: "More funding_satoshis than there are satoshis!", msg: Some(msgs::ErrorAction::DisconnectPeer{})});
 		}
 		if msg.channel_reserve_satoshis > msg.funding_satoshis {
-			return Err(HandleError{err: "Bogus channel_reserve_satoshis", msg: None});
+			return Err(HandleError{err: "Bogus channel_reserve_satoshis", msg: Some(msgs::ErrorAction::DisconnectPeer{})});
 		}
 		if msg.push_msat > (msg.funding_satoshis - msg.channel_reserve_satoshis) * 1000 {
-			return Err(HandleError{err: "push_msat more than highest possible value", msg: None});
+			return Err(HandleError{err: "push_msat more than highest possible value", msg: Some(msgs::ErrorAction::DisconnectPeer{})});
 		}
-		if msg.dust_limit_satoshis > 21000000 * 100000000 {
-			return Err(HandleError{err: "Peer never wants payout outputs?", msg: None});
+		if msg.dust_limit_satoshis > msg.funding_satoshis {
+			return Err(HandleError{err: "Peer never wants payout outputs?", msg: Some(msgs::ErrorAction::DisconnectPeer{})});
 		}
 		if msg.max_htlc_value_in_flight_msat > msg.funding_satoshis * 1000 {
-			return Err(HandleError{err: "Bogus max_htlc_value_in_flight_satoshis", msg: None});
+			return Err(HandleError{err: "Bogus max_htlc_value_in_flight_satoshis", msg: Some(msgs::ErrorAction::DisconnectPeer{})});
 		}
 		if msg.htlc_minimum_msat >= (msg.funding_satoshis - msg.channel_reserve_satoshis) * 1000 {
-			return Err(HandleError{err: "Minimum htlc value is full channel value", msg: None});
+			return Err(HandleError{err: "Minimum htlc value is full channel value", msg: Some(msgs::ErrorAction::DisconnectPeer{})});
 		}
 		Channel::check_remote_fee(fee_estimator, msg.feerate_per_kw)?;
 		if msg.to_self_delay > MAX_LOCAL_BREAKDOWN_TIMEOUT {
-			return Err(HandleError{err: "They wanted our payments to be delayed by a needlessly long period", msg: None});
+			return Err(HandleError{err: "They wanted our payments to be delayed by a needlessly long period", msg: Some(msgs::ErrorAction::DisconnectPeer{})});
 		}
 		if msg.max_accepted_htlcs < 1 {
-			return Err(HandleError{err: "0 max_accpted_htlcs makes for a useless channel", msg: None});
+			return Err(HandleError{err: "0 max_accpted_htlcs makes for a useless channel", msg: Some(msgs::ErrorAction::DisconnectPeer{})});
 		}
 		if (msg.channel_flags & 254) != 0 {
-			return Err(HandleError{err: "unknown channel_flags", msg: None});
+			return Err(HandleError{err: "unknown channel_flags", msg: Some(msgs::ErrorAction::DisconnectPeer{})});
 		}
 
 		// Convert things into internal flags and prep our state:
@@ -389,21 +479,15 @@ impl Channel {
 
 		let background_feerate = fee_estimator.get_est_sat_per_vbyte(ConfirmationTarget::Background);
 
-		let mut key_seed = [0u8; 32];
-		rng::fill_bytes(&mut key_seed);
-		let chan_keys = match ChannelKeys::new_from_seed(&key_seed) {
-			Ok(key) => key,
-			Err(_) => panic!("RNG is busted!")
-		};
-
 		let secp_ctx = Secp256k1::new();
 		let our_channel_monitor_claim_key_hash = Hash160::from_data(&PublicKey::from_secret_key(&secp_ctx, &chan_keys.channel_monitor_claim_key).unwrap().serialize());
 		let our_channel_monitor_claim_script = Builder::new().push_opcode(opcodes::All::OP_PUSHBYTES_0).push_slice(&our_channel_monitor_claim_key_hash[..]).into_script();
 		let mut channel_monitor = ChannelMonitor::new(&chan_keys.revocation_base_key,
-		                                          &PublicKey::from_secret_key(&secp_ctx, &chan_keys.delayed_payment_base_key).unwrap(),
-		                                          &PublicKey::from_secret_key(&secp_ctx, &chan_keys.htlc_base_key).unwrap(),
-		                                          BREAKDOWN_TIMEOUT, our_channel_monitor_claim_script);
+		                                              &PublicKey::from_secret_key(&secp_ctx, &chan_keys.delayed_payment_base_key).unwrap(),
+		                                              &chan_keys.htlc_base_key,
+		                                              BREAKDOWN_TIMEOUT, our_channel_monitor_claim_script);
 		channel_monitor.set_their_htlc_base_key(&msg.htlc_basepoint);
+		channel_monitor.set_their_to_self_delay(msg.to_self_delay);
 
 		let mut chan = Channel {
 			user_id: user_id,
@@ -419,10 +503,14 @@ impl Channel {
 			cur_remote_commitment_transaction_number: (1 << 48) - 1,
 			value_to_self_msat: msg.push_msat,
 			pending_htlcs: Vec::new(),
-			holding_cell_htlcs: Vec::new(),
+			holding_cell_htlc_updates: Vec::new(),
 			next_local_htlc_id: 0,
 			next_remote_htlc_id: 0,
-			channel_update_count: 0,
+			channel_update_count: 1,
+
+			last_local_commitment_txn: Vec::new(),
+
+			last_sent_closing_fee: None,
 
 			funding_tx_confirmed_in: Default::default(),
 			short_channel_id: None,
@@ -446,8 +534,12 @@ impl Channel {
 			their_delayed_payment_basepoint: msg.delayed_payment_basepoint,
 			their_htlc_basepoint: msg.htlc_basepoint,
 			their_cur_commitment_point: msg.first_per_commitment_point,
+
+			their_prev_commitment_point: None,
 			their_node_id: their_node_id,
 
+			their_shutdown_scriptpubkey: None,
+
 			channel_monitor: channel_monitor,
 		};
 
@@ -459,9 +551,9 @@ impl Channel {
 
 	// Utilities to derive keys:
 
-	fn build_local_commitment_secret(&self, idx: u64) -> Result<SecretKey, HandleError> {
+	fn build_local_commitment_secret(&self, idx: u64) -> SecretKey {
 		let res = chan_utils::build_commitment_secret(self.local_keys.commitment_seed, idx);
-		Ok(get_key!(&self.secp_ctx, &res))
+		SecretKey::from_slice(&self.secp_ctx, &res).unwrap()
 	}
 
 	// Utilities to build transactions:
@@ -502,35 +594,48 @@ impl Channel {
 	/// generated by the peer which proposed adding the HTLCs, and thus we need to understand both
 	/// which peer generated this transaction and "to whom" this transaction flows.
 	#[inline]
-	fn build_commitment_transaction(&self, commitment_number: u64, keys: &TxCreationKeys, local: bool, generated_by_local: bool) -> Result<(Transaction, Vec<HTLCOutputInCommitment>), HandleError> {
+	fn build_commitment_transaction(&self, commitment_number: u64, keys: &TxCreationKeys, local: bool, generated_by_local: bool) -> (Transaction, Vec<HTLCOutputInCommitment>) {
 		let obscured_commitment_transaction_number = self.get_commitment_transaction_number_obscure_factor() ^ commitment_number;
 
 		let txins = {
 			let mut ins: Vec<TxIn> = Vec::new();
 			ins.push(TxIn {
-				prev_hash: self.channel_monitor.get_funding_txo().unwrap().0,
-				prev_index: self.channel_monitor.get_funding_txo().unwrap().1 as u32,
+				prev_hash: self.channel_monitor.get_funding_txo().unwrap().txid,
+				prev_index: self.channel_monitor.get_funding_txo().unwrap().index as u32,
 				script_sig: Script::new(),
-				sequence: ((0x80 as u32) << 8*3) | ((obscured_commitment_transaction_number >> 3*8) as u32)
+				sequence: ((0x80 as u32) << 8*3) | ((obscured_commitment_transaction_number >> 3*8) as u32),
+				witness: Vec::new(),
 			});
 			ins
 		};
-		let mut witness: Vec<Vec<Vec<u8>>> = Vec::new();
-		witness.push(Vec::new());
 
-		let mut txouts: Vec<(TxOut, Option<HTLCOutputInCommitment>)> = Vec::new();
+		let mut txouts: Vec<(TxOut, Option<HTLCOutputInCommitment>)> = Vec::with_capacity(self.pending_htlcs.len() + 2);
 
 		let dust_limit_satoshis = if local { self.our_dust_limit_satoshis } else { self.their_dust_limit_satoshis };
 		let mut remote_htlc_total_msat = 0;
 		let mut local_htlc_total_msat = 0;
+		let mut value_to_self_msat_offset = 0;
 
 		for ref htlc in self.pending_htlcs.iter() {
-			if htlc.state == HTLCState::Committed || htlc.state == (if generated_by_local { HTLCState::LocalAnnounced } else { HTLCState::RemoteAnnounced }) {
+			let include = match htlc.state {
+				HTLCState::RemoteAnnounced => !generated_by_local,
+				HTLCState::AwaitingRemoteRevokeToAnnounce => !generated_by_local,
+				HTLCState::AwaitingAnnouncedRemoteRevoke => true,
+				HTLCState::LocalAnnounced => generated_by_local,
+				HTLCState::Committed => true,
+				HTLCState::RemoteRemoved => generated_by_local,
+				HTLCState::AwaitingRemoteRevokeToRemove => generated_by_local,
+				HTLCState::AwaitingRemovedRemoteRevoke => false,
+				HTLCState::LocalRemoved => !generated_by_local,
+				HTLCState::LocalRemovedAwaitingCommitment => false,
+			};
+
+			if include {
 				if htlc.outbound == local { // "offered HTLC output"
 					if htlc.amount_msat / 1000 >= dust_limit_satoshis + (self.feerate_per_kw * HTLC_TIMEOUT_TX_WEIGHT / 1000) {
 						let htlc_in_tx = htlc.get_in_commitment(true);
 						txouts.push((TxOut {
-							script_pubkey: chan_utils::get_htlc_redeemscript(&htlc_in_tx, &keys, true).to_v0_p2wsh(),
+							script_pubkey: chan_utils::get_htlc_redeemscript(&htlc_in_tx, &keys).to_v0_p2wsh(),
 							value: htlc.amount_msat / 1000
 						}, Some(htlc_in_tx)));
 					}
@@ -538,7 +643,7 @@ impl Channel {
 					if htlc.amount_msat / 1000 >= dust_limit_satoshis + (self.feerate_per_kw * HTLC_SUCCESS_TX_WEIGHT / 1000) {
 						let htlc_in_tx = htlc.get_in_commitment(false);
 						txouts.push((TxOut { // "received HTLC output"
-							script_pubkey: chan_utils::get_htlc_redeemscript(&htlc_in_tx, &keys, false).to_v0_p2wsh(),
+							script_pubkey: chan_utils::get_htlc_redeemscript(&htlc_in_tx, &keys).to_v0_p2wsh(),
 							value: htlc.amount_msat / 1000
 						}, Some(htlc_in_tx)));
 					}
@@ -548,12 +653,29 @@ impl Channel {
 				} else {
 					remote_htlc_total_msat += htlc.amount_msat;
 				}
+			} else {
+				match htlc.state {
+					HTLCState::AwaitingRemoteRevokeToRemove|HTLCState::AwaitingRemovedRemoteRevoke => {
+						if generated_by_local && htlc.fail_reason.is_none() {
+							value_to_self_msat_offset -= htlc.amount_msat as i64;
+						}
+					},
+					HTLCState::LocalRemoved => {
+						if !generated_by_local && htlc.local_removed_fulfilled {
+							value_to_self_msat_offset += htlc.amount_msat as i64;
+						}
+					},
+					HTLCState::LocalRemovedAwaitingCommitment => {
+						value_to_self_msat_offset += htlc.amount_msat as i64;
+					},
+					_ => {},
+				}
 			}
 		}
 
 		let total_fee: u64 = self.feerate_per_kw * (COMMITMENT_TX_BASE_WEIGHT + (txouts.len() as u64) * COMMITMENT_TX_WEIGHT_PER_HTLC) / 1000;
-		let value_to_self: i64 = ((self.value_to_self_msat - local_htlc_total_msat) as i64) / 1000 - if self.channel_outbound { total_fee as i64 } else { 0 };
-		let value_to_remote: i64 = (((self.channel_value_satoshis * 1000 - self.value_to_self_msat - remote_htlc_total_msat) / 1000) as i64) - if self.channel_outbound { 0 } else { total_fee as i64 };
+		let value_to_self: i64 = ((self.value_to_self_msat - local_htlc_total_msat) as i64 + value_to_self_msat_offset) / 1000 - if self.channel_outbound { total_fee as i64 } else { 0 };
+		let value_to_remote: i64 = (((self.channel_value_satoshis * 1000 - self.value_to_self_msat - remote_htlc_total_msat) as i64 - value_to_self_msat_offset) / 1000) - if self.channel_outbound { 0 } else { total_fee as i64 };
 
 		let value_to_a = if local { value_to_self } else { value_to_remote };
 		let value_to_b = if local { value_to_remote } else { value_to_self };
@@ -578,26 +700,91 @@ impl Channel {
 
 		transaction_utils::sort_outputs(&mut txouts);
 
-		let mut outputs: Vec<TxOut> = Vec::new();
-		let mut htlcs_used: Vec<HTLCOutputInCommitment> = Vec::new();
+		let mut outputs: Vec<TxOut> = Vec::with_capacity(txouts.len());
+		let mut htlcs_used: Vec<HTLCOutputInCommitment> = Vec::with_capacity(txouts.len());
 		for (idx, out) in txouts.drain(..).enumerate() {
 			outputs.push(out.0);
-			match out.1 {
-				Some(out_htlc) => {
-					htlcs_used.push(out_htlc);
-					htlcs_used.last_mut().unwrap().transaction_output_index = idx as u32;
-				},
-				None => {}
+			if let Some(out_htlc) = out.1 {
+				htlcs_used.push(out_htlc);
+				htlcs_used.last_mut().unwrap().transaction_output_index = idx as u32;
 			}
 		}
 
-		Ok((Transaction {
+		(Transaction {
 			version: 2,
 			lock_time: ((0x20 as u32) << 8*3) | ((obscured_commitment_transaction_number & 0xffffffu64) as u32),
 			input: txins,
 			output: outputs,
-			witness: witness
-		}, htlcs_used))
+		}, htlcs_used)
+	}
+
+	#[inline]
+	fn get_closing_scriptpubkey(&self) -> Script {
+		let our_channel_close_key_hash = Hash160::from_data(&PublicKey::from_secret_key(&self.secp_ctx, &self.local_keys.channel_close_key).unwrap().serialize());
+		Builder::new().push_opcode(opcodes::All::OP_PUSHBYTES_0).push_slice(&our_channel_close_key_hash[..]).into_script()
+	}
+
+	#[inline]
+	fn get_closing_transaction_weight(a_scriptpubkey: &Script, b_scriptpubkey: &Script) -> u64 {
+		(4 + 1 + 36 + 4 + 1 + 1 + 2*(8+1) + 4 + a_scriptpubkey.len() as u64 + b_scriptpubkey.len() as u64)*4 + 2 + 1 + 1 + 2*(1 + 72)
+	}
+
+	#[inline]
+	fn build_closing_transaction(&self, proposed_total_fee_satoshis: u64, skip_remote_output: bool) -> (Transaction, u64) {
+		let txins = {
+			let mut ins: Vec<TxIn> = Vec::new();
+			ins.push(TxIn {
+				prev_hash: self.channel_monitor.get_funding_txo().unwrap().txid,
+				prev_index: self.channel_monitor.get_funding_txo().unwrap().index as u32,
+				script_sig: Script::new(),
+				sequence: 0xffffffff,
+				witness: Vec::new(),
+			});
+			ins
+		};
+
+		assert!(self.pending_htlcs.is_empty());
+		let mut txouts: Vec<(TxOut, ())> = Vec::new();
+
+		let mut total_fee_satoshis = proposed_total_fee_satoshis;
+		let value_to_self: i64 = (self.value_to_self_msat as i64) / 1000 - if self.channel_outbound { total_fee_satoshis as i64 } else { 0 };
+		let value_to_remote: i64 = ((self.channel_value_satoshis * 1000 - self.value_to_self_msat) as i64 / 1000) - if self.channel_outbound { 0 } else { total_fee_satoshis as i64 };
+
+		if value_to_self < 0 {
+			assert!(self.channel_outbound);
+			total_fee_satoshis += (-value_to_self) as u64;
+		} else if value_to_remote < 0 {
+			assert!(!self.channel_outbound);
+			total_fee_satoshis += (-value_to_remote) as u64;
+		}
+
+		if !skip_remote_output && value_to_remote as u64 > self.our_dust_limit_satoshis {
+			txouts.push((TxOut {
+				script_pubkey: self.their_shutdown_scriptpubkey.clone().unwrap(),
+				value: value_to_remote as u64
+			}, ()));
+		}
+
+		if value_to_self as u64 > self.our_dust_limit_satoshis {
+			txouts.push((TxOut {
+				script_pubkey: self.get_closing_scriptpubkey(),
+				value: value_to_self as u64
+			}, ()));
+		}
+
+		transaction_utils::sort_outputs(&mut txouts);
+
+		let mut outputs: Vec<TxOut> = Vec::new();
+		for out in txouts.drain(..) {
+			outputs.push(out.0);
+		}
+
+		(Transaction {
+			version: 2,
+			lock_time: 0,
+			input: txins,
+			output: outputs,
+		}, total_fee_satoshis)
 	}
 
 	#[inline]
@@ -607,11 +794,11 @@ impl Channel {
 	/// The result is a transaction which we can revoke ownership of (ie a "local" transaction)
 	/// TODO Some magic rust shit to compile-time check this?
 	fn build_local_transaction_keys(&self, commitment_number: u64) -> Result<TxCreationKeys, HandleError> {
-		let per_commitment_point = PublicKey::from_secret_key(&self.secp_ctx, &self.build_local_commitment_secret(commitment_number)?).unwrap();
+		let per_commitment_point = PublicKey::from_secret_key(&self.secp_ctx, &self.build_local_commitment_secret(commitment_number)).unwrap();
 		let delayed_payment_base = PublicKey::from_secret_key(&self.secp_ctx, &self.local_keys.delayed_payment_base_key).unwrap();
 		let htlc_basepoint = PublicKey::from_secret_key(&self.secp_ctx, &self.local_keys.htlc_base_key).unwrap();
 
-		Ok(secp_call!(TxCreationKeys::new(&self.secp_ctx, &per_commitment_point, &delayed_payment_base, &htlc_basepoint, &self.their_revocation_basepoint, &self.their_payment_basepoint, &self.their_htlc_basepoint)))
+		Ok(secp_derived_key!(TxCreationKeys::new(&self.secp_ctx, &per_commitment_point, &delayed_payment_base, &htlc_basepoint, &self.their_revocation_basepoint, &self.their_payment_basepoint, &self.their_htlc_basepoint)))
 	}
 
 	#[inline]
@@ -624,7 +811,7 @@ impl Channel {
 		let revocation_basepoint = PublicKey::from_secret_key(&self.secp_ctx, &self.local_keys.revocation_base_key).unwrap();
 		let htlc_basepoint = PublicKey::from_secret_key(&self.secp_ctx, &self.local_keys.htlc_base_key).unwrap();
 
-		Ok(secp_call!(TxCreationKeys::new(&self.secp_ctx, &self.their_cur_commitment_point, &self.their_delayed_payment_basepoint, &self.their_htlc_basepoint, &revocation_basepoint, &payment_basepoint, &htlc_basepoint)))
+		Ok(secp_derived_key!(TxCreationKeys::new(&self.secp_ctx, &self.their_cur_commitment_point, &self.their_delayed_payment_basepoint, &self.their_htlc_basepoint, &revocation_basepoint, &payment_basepoint, &htlc_basepoint)))
 	}
 
 	/// Gets the redeemscript for the funding transaction output (ie the funding transaction output
@@ -642,182 +829,243 @@ impl Channel {
 		}.push_opcode(opcodes::All::OP_PUSHNUM_2).push_opcode(opcodes::All::OP_CHECKMULTISIG).into_script()
 	}
 
-	fn sign_commitment_transaction(&self, tx: &mut Transaction, their_sig: &Signature) -> Result<(), HandleError> {
+	fn sign_commitment_transaction(&self, tx: &mut Transaction, their_sig: &Signature) -> Signature {
 		if tx.input.len() != 1 {
 			panic!("Tried to sign commitment transaction that had input count != 1!");
 		}
-		if tx.witness.len() != 1 || tx.witness[0].len() != 0 {
+		if tx.input[0].witness.len() != 0 {
 			panic!("Tried to re-sign commitment transaction");
 		}
 
 		let funding_redeemscript = self.get_funding_redeemscript();
 
-		let sighash = secp_call!(Message::from_slice(&bip143::SighashComponents::new(&tx).sighash_all(&tx, 0, &funding_redeemscript, self.channel_value_satoshis)[..]));
-		let our_sig = secp_call!(self.secp_ctx.sign(&sighash, &self.local_keys.funding_key));
+		let sighash = Message::from_slice(&bip143::SighashComponents::new(&tx).sighash_all(&tx.input[0], &funding_redeemscript, self.channel_value_satoshis)[..]).unwrap();
+		let our_sig = self.secp_ctx.sign(&sighash, &self.local_keys.funding_key).unwrap();
 
-		tx.witness[0].push(Vec::new()); // First is the multisig dummy
+		tx.input[0].witness.push(Vec::new()); // First is the multisig dummy
 
 		let our_funding_key = PublicKey::from_secret_key(&self.secp_ctx, &self.local_keys.funding_key).unwrap().serialize();
 		let their_funding_key = self.their_funding_pubkey.serialize();
 		if our_funding_key[..] < their_funding_key[..] {
-			tx.witness[0].push(our_sig.serialize_der(&self.secp_ctx).to_vec());
-			tx.witness[0].push(their_sig.serialize_der(&self.secp_ctx).to_vec());
+			tx.input[0].witness.push(our_sig.serialize_der(&self.secp_ctx).to_vec());
+			tx.input[0].witness.push(their_sig.serialize_der(&self.secp_ctx).to_vec());
 		} else {
-			tx.witness[0].push(their_sig.serialize_der(&self.secp_ctx).to_vec());
-			tx.witness[0].push(our_sig.serialize_der(&self.secp_ctx).to_vec());
+			tx.input[0].witness.push(their_sig.serialize_der(&self.secp_ctx).to_vec());
+			tx.input[0].witness.push(our_sig.serialize_der(&self.secp_ctx).to_vec());
 		}
-		tx.witness[0][1].push(SigHashType::All as u8);
-		tx.witness[0][2].push(SigHashType::All as u8);
+		tx.input[0].witness[1].push(SigHashType::All as u8);
+		tx.input[0].witness[2].push(SigHashType::All as u8);
 
-		tx.witness[0].push(funding_redeemscript.into_vec());
+		tx.input[0].witness.push(funding_redeemscript.into_vec());
 
-		Ok(())
+		our_sig
 	}
 
 	/// Builds the htlc-success or htlc-timeout transaction which spends a given HTLC output
 	/// @local is used only to convert relevant internal structures which refer to remote vs local
 	/// to decide value of outputs and direction of HTLCs.
-	fn build_htlc_transaction(&self, prev_hash: &Sha256dHash, htlc: &HTLCOutputInCommitment, local: bool, keys: &TxCreationKeys) -> Result<Transaction, HandleError> {
-		let mut txins: Vec<TxIn> = Vec::new();
-		txins.push(TxIn {
-			prev_hash: prev_hash.clone(),
-			prev_index: htlc.transaction_output_index,
-			script_sig: Script::new(),
-			sequence: 0
-		});
-
-		let mut witnesses: Vec<Vec<Vec<u8>>> = Vec::new();
-		witnesses.push(Vec::new());
+	fn build_htlc_transaction(&self, prev_hash: &Sha256dHash, htlc: &HTLCOutputInCommitment, local: bool, keys: &TxCreationKeys) -> Transaction {
+		chan_utils::build_htlc_transaction(prev_hash, self.feerate_per_kw, if local { self.their_to_self_delay } else { BREAKDOWN_TIMEOUT }, htlc, &keys.a_delayed_payment_key, &keys.revocation_key)
+	}
 
-		let total_fee = if htlc.offered {
-				self.feerate_per_kw * HTLC_TIMEOUT_TX_WEIGHT / 1000
-			} else {
-				self.feerate_per_kw * HTLC_SUCCESS_TX_WEIGHT / 1000
-			};
+	fn create_htlc_tx_signature(&self, tx: &Transaction, htlc: &HTLCOutputInCommitment, keys: &TxCreationKeys) -> Result<(Script, Signature, bool), HandleError> {
+		if tx.input.len() != 1 {
+			panic!("Tried to sign HTLC transaction that had input count != 1!");
+		}
 
-		let mut txouts: Vec<TxOut> = Vec::new();
-		txouts.push(TxOut {
-			script_pubkey: chan_utils::get_revokeable_redeemscript(&keys.revocation_key,
-			                                                       if local { self.their_to_self_delay } else { BREAKDOWN_TIMEOUT },
-			                                                       &keys.a_delayed_payment_key).to_v0_p2wsh(),
-			value: htlc.amount_msat / 1000 - total_fee //TODO: BOLT 3 does not specify if we should add amount_msat before dividing or if we should divide by 1000 before subtracting (as we do here)
-		});
+		let htlc_redeemscript = chan_utils::get_htlc_redeemscript(&htlc, &keys);
 
-		Ok(Transaction {
-			version: 2,
-			lock_time: if htlc.offered { htlc.cltv_expiry } else { 0 },
-			input: txins,
-			output: txouts,
-			witness: witnesses
-		})
+		let our_htlc_key = secp_derived_key!(chan_utils::derive_private_key(&self.secp_ctx, &keys.per_commitment_point, &self.local_keys.htlc_base_key));
+		let sighash = Message::from_slice(&bip143::SighashComponents::new(&tx).sighash_all(&tx.input[0], &htlc_redeemscript, htlc.amount_msat / 1000)[..]).unwrap();
+		let is_local_tx = PublicKey::from_secret_key(&self.secp_ctx, &our_htlc_key).unwrap() == keys.a_htlc_key;
+		Ok((htlc_redeemscript, self.secp_ctx.sign(&sighash, &our_htlc_key).unwrap(), is_local_tx))
 	}
 
 	/// Signs a transaction created by build_htlc_transaction. If the transaction is an
 	/// HTLC-Success transaction (ie htlc.offered is false), preimate must be set!
-	fn sign_htlc_transaction(&self, tx: &mut Transaction, their_sig: &Signature, preimage: &Option<[u8; 32]>, htlc: &HTLCOutputInCommitment, keys: &TxCreationKeys) -> Result<(), HandleError> {
+	fn sign_htlc_transaction(&self, tx: &mut Transaction, their_sig: &Signature, preimage: &Option<[u8; 32]>, htlc: &HTLCOutputInCommitment, keys: &TxCreationKeys) -> Result<Signature, HandleError> {
 		if tx.input.len() != 1 {
 			panic!("Tried to sign HTLC transaction that had input count != 1!");
 		}
-		if tx.witness.len() != 1 || tx.witness[0].len() != 0 {
+		if tx.input[0].witness.len() != 0 {
 			panic!("Tried to re-sign HTLC transaction");
 		}
 
-		let htlc_redeemscript = chan_utils::get_htlc_redeemscript(&htlc, &keys, htlc.offered);
+		let (htlc_redeemscript, our_sig, local_tx) = self.create_htlc_tx_signature(tx, htlc, keys)?;
 
-		let our_htlc_key = secp_call!(chan_utils::derive_private_key(&self.secp_ctx, &keys.per_commitment_point, &self.local_keys.htlc_base_key));
-		let sighash = secp_call!(Message::from_slice(&bip143::SighashComponents::new(&tx).sighash_all(&tx, 0, &htlc_redeemscript, htlc.amount_msat / 1000)[..]));
-		let our_sig = secp_call!(self.secp_ctx.sign(&sighash, &our_htlc_key));
-
-		let local_tx = PublicKey::from_secret_key(&self.secp_ctx, &our_htlc_key).unwrap() == keys.a_htlc_key;
-
-		tx.witness[0].push(Vec::new()); // First is the multisig dummy
+		tx.input[0].witness.push(Vec::new()); // First is the multisig dummy
 
 		if local_tx { // b, then a
-			tx.witness[0].push(their_sig.serialize_der(&self.secp_ctx).to_vec());
-			tx.witness[0].push(our_sig.serialize_der(&self.secp_ctx).to_vec());
+			tx.input[0].witness.push(their_sig.serialize_der(&self.secp_ctx).to_vec());
+			tx.input[0].witness.push(our_sig.serialize_der(&self.secp_ctx).to_vec());
 		} else {
-			tx.witness[0].push(our_sig.serialize_der(&self.secp_ctx).to_vec());
-			tx.witness[0].push(their_sig.serialize_der(&self.secp_ctx).to_vec());
+			tx.input[0].witness.push(our_sig.serialize_der(&self.secp_ctx).to_vec());
+			tx.input[0].witness.push(their_sig.serialize_der(&self.secp_ctx).to_vec());
 		}
-		tx.witness[0][1].push(SigHashType::All as u8);
-		tx.witness[0][2].push(SigHashType::All as u8);
+		tx.input[0].witness[1].push(SigHashType::All as u8);
+		tx.input[0].witness[2].push(SigHashType::All as u8);
 
 		if htlc.offered {
-			tx.witness[0].push(Vec::new());
+			tx.input[0].witness.push(Vec::new());
 		} else {
-			tx.witness[0].push(preimage.unwrap().to_vec());
+			tx.input[0].witness.push(preimage.unwrap().to_vec());
 		}
 
-		tx.witness[0].push(htlc_redeemscript.into_vec());
+		tx.input[0].witness.push(htlc_redeemscript.into_vec());
 
-		Ok(())
+		Ok(our_sig)
 	}
 
-	pub fn get_update_fulfill_htlc(&mut self, payment_preimage: [u8; 32]) -> Result<msgs::UpdateFulfillHTLC, HandleError> {
+	pub fn get_update_fulfill_htlc(&mut self, payment_preimage_arg: [u8; 32]) -> Result<Option<(msgs::UpdateFulfillHTLC, ChannelMonitor)>, HandleError> {
+		// Either ChannelFunded got set (which means it wont bet unset) or there is no way any
+		// caller thought we could have something claimed (cause we wouldn't have accepted in an
+		// incoming HTLC anyway). If we got to ShutdownComplete, callers aren't allowed to call us,
+		// either.
 		if (self.channel_state & (ChannelState::ChannelFunded as u32)) != (ChannelState::ChannelFunded as u32) {
-			return Err(HandleError{err: "Was asked to fulfill an HTLC when channel was not in an operational state", msg: None});
+			panic!("Was asked to fulfill an HTLC when channel was not in an operational state");
 		}
+		assert_eq!(self.channel_state & ChannelState::ShutdownComplete as u32, 0);
 
 		let mut sha = Sha256::new();
-		sha.input(&payment_preimage);
-		let mut payment_hash = [0; 32];
-		sha.result(&mut payment_hash);
+		sha.input(&payment_preimage_arg);
+		let mut payment_hash_calc = [0; 32];
+		sha.result(&mut payment_hash_calc);
+
+		// Now update local state:
+		if (self.channel_state & (ChannelState::AwaitingRemoteRevoke as u32)) == (ChannelState::AwaitingRemoteRevoke as u32) {
+			for pending_update in self.holding_cell_htlc_updates.iter() {
+				match pending_update {
+					&HTLCUpdateAwaitingACK::ClaimHTLC { ref payment_preimage, .. } => {
+						if payment_preimage_arg == *payment_preimage {
+							return Ok(None);
+						}
+					},
+					&HTLCUpdateAwaitingACK::FailHTLC { ref payment_hash, .. } => {
+						if payment_hash_calc == *payment_hash {
+							return Err(HandleError{err: "Unable to find a pending HTLC which matched the given payment preimage", msg: None});
+						}
+					},
+					_ => {}
+				}
+			}
+			self.holding_cell_htlc_updates.push(HTLCUpdateAwaitingACK::ClaimHTLC {
+				payment_preimage: payment_preimage_arg, payment_hash: payment_hash_calc,
+			});
+			return Ok(None);
+		}
 
 		let mut htlc_id = 0;
 		let mut htlc_amount_msat = 0;
-		self.pending_htlcs.retain(|ref htlc| {
-			if !htlc.outbound && htlc.payment_hash == payment_hash {
+		for htlc in self.pending_htlcs.iter_mut() {
+			if !htlc.outbound && htlc.payment_hash == payment_hash_calc {
 				if htlc_id != 0 {
 					panic!("Duplicate HTLC payment_hash, you probably re-used payment preimages, NEVER DO THIS!");
 				}
 				htlc_id = htlc.htlc_id;
 				htlc_amount_msat += htlc.amount_msat;
-				false
-			} else { true }
-		});
+				if htlc.state == HTLCState::Committed {
+					htlc.state = HTLCState::LocalRemoved;
+					htlc.local_removed_fulfilled = true;
+				} else if htlc.state == HTLCState::RemoteAnnounced {
+					panic!("Somehow forwarded HTLC prior to remote revocation!");
+				} else if htlc.state == HTLCState::LocalRemoved || htlc.state == HTLCState::LocalRemovedAwaitingCommitment {
+					return Err(HandleError{err: "Unable to find a pending HTLC which matched the given payment preimage", msg: None});
+				} else {
+					panic!("Have an inbound HTLC when not awaiting remote revoke that had a garbage state");
+				}
+			}
+		}
 		if htlc_amount_msat == 0 {
 			return Err(HandleError{err: "Unable to find a pending HTLC which matched the given payment preimage", msg: None});
 		}
+		self.channel_monitor.provide_payment_preimage(&payment_hash_calc, &payment_preimage_arg);
 
-		//TODO: This is racy af, they may have pending messages in flight to us that will not have
-		//received this yet!
-		self.value_to_self_msat += htlc_amount_msat;
-		Ok(msgs::UpdateFulfillHTLC {
+		Ok(Some((msgs::UpdateFulfillHTLC {
 			channel_id: self.channel_id(),
 			htlc_id: htlc_id,
-			payment_preimage: payment_preimage,
-		})
+			payment_preimage: payment_preimage_arg,
+		}, self.channel_monitor.clone())))
+	}
+
+	pub fn get_update_fulfill_htlc_and_commit(&mut self, payment_preimage: [u8; 32]) -> Result<Option<(msgs::UpdateFulfillHTLC, msgs::CommitmentSigned, ChannelMonitor)>, HandleError> {
+		match self.get_update_fulfill_htlc(payment_preimage)? {
+			Some(update_fulfill_htlc) => {
+				let (commitment, monitor_update) = self.send_commitment_no_status_check()?;
+				Ok(Some((update_fulfill_htlc.0, commitment, monitor_update)))
+			},
+			None => Ok(None)
+		}
 	}
 
-	pub fn get_update_fail_htlc(&mut self, payment_hash: &[u8; 32], err_packet: msgs::OnionErrorPacket) -> Result<msgs::UpdateFailHTLC, HandleError> {
+	pub fn get_update_fail_htlc(&mut self, payment_hash_arg: &[u8; 32], err_packet: msgs::OnionErrorPacket) -> Result<Option<msgs::UpdateFailHTLC>, HandleError> {
 		if (self.channel_state & (ChannelState::ChannelFunded as u32)) != (ChannelState::ChannelFunded as u32) {
 			return Err(HandleError{err: "Was asked to fail an HTLC when channel was not in an operational state", msg: None});
 		}
+		assert_eq!(self.channel_state & ChannelState::ShutdownComplete as u32, 0);
+
+		// Now update local state:
+		if (self.channel_state & (ChannelState::AwaitingRemoteRevoke as u32)) == (ChannelState::AwaitingRemoteRevoke as u32) {
+			for pending_update in self.holding_cell_htlc_updates.iter() {
+				match pending_update {
+					&HTLCUpdateAwaitingACK::ClaimHTLC { ref payment_hash, .. } => {
+						if *payment_hash_arg == *payment_hash {
+							return Err(HandleError{err: "Unable to find a pending HTLC which matched the given payment preimage", msg: None});
+						}
+					},
+					&HTLCUpdateAwaitingACK::FailHTLC { ref payment_hash, .. } => {
+						if *payment_hash_arg == *payment_hash {
+							return Ok(None);
+						}
+					},
+					_ => {}
+				}
+			}
+			self.holding_cell_htlc_updates.push(HTLCUpdateAwaitingACK::FailHTLC {
+				payment_hash: payment_hash_arg.clone(),
+				err_packet,
+			});
+			return Ok(None);
+		}
 
 		let mut htlc_id = 0;
 		let mut htlc_amount_msat = 0;
-		self.pending_htlcs.retain(|ref htlc| {
-			if !htlc.outbound && htlc.payment_hash == *payment_hash {
+		for htlc in self.pending_htlcs.iter_mut() {
+			if !htlc.outbound && htlc.payment_hash == *payment_hash_arg {
 				if htlc_id != 0 {
 					panic!("Duplicate HTLC payment_hash, you probably re-used payment preimages, NEVER DO THIS!");
 				}
 				htlc_id = htlc.htlc_id;
 				htlc_amount_msat += htlc.amount_msat;
-				false
-			} else { true }
-		});
+				if htlc.state == HTLCState::Committed {
+					htlc.state = HTLCState::LocalRemoved;
+				} else if htlc.state == HTLCState::RemoteAnnounced {
+					panic!("Somehow forwarded HTLC prior to remote revocation!");
+				} else if htlc.state == HTLCState::LocalRemoved || htlc.state == HTLCState::LocalRemovedAwaitingCommitment {
+					return Err(HandleError{err: "Unable to find a pending HTLC which matched the given payment preimage", msg: None});
+				} else {
+					panic!("Have an inbound HTLC when not awaiting remote revoke that had a garbage state");
+				}
+			}
+		}
 		if htlc_amount_msat == 0 {
 			return Err(HandleError{err: "Unable to find a pending HTLC which matched the given payment preimage", msg: None});
 		}
 
-		//TODO: This is racy af, they may have pending messages in flight to us that will not have
-		//received this yet!
-
-		Ok(msgs::UpdateFailHTLC {
+		Ok(Some(msgs::UpdateFailHTLC {
 			channel_id: self.channel_id(),
 			htlc_id,
 			reason: err_packet
-		})
+		}))
+	}
+
+	pub fn get_update_fail_htlc_and_commit(&mut self, payment_hash: &[u8; 32], err_packet: msgs::OnionErrorPacket) -> Result<Option<(msgs::UpdateFailHTLC, msgs::CommitmentSigned, ChannelMonitor)>, HandleError> {
+		match self.get_update_fail_htlc(payment_hash, err_packet)? {
+			Some(update_fail_htlc) => {
+				let (commitment, monitor_update) = self.send_commitment_no_status_check()?;
+				Ok(Some((update_fail_htlc, commitment, monitor_update)))
+			},
+			None => Ok(None)
+		}
 	}
 
 	// Message handlers:
@@ -867,6 +1115,7 @@ impl Channel {
 
 		let obscure_factor = self.get_commitment_transaction_number_obscure_factor();
 		self.channel_monitor.set_commitment_obscure_factor(obscure_factor);
+		self.channel_monitor.set_their_to_self_delay(msg.to_self_delay);
 
 		self.channel_state = ChannelState::OurInitSent as u32 | ChannelState::TheirInitSent as u32;
 
@@ -877,21 +1126,21 @@ impl Channel {
 		let funding_script = self.get_funding_redeemscript();
 
 		let remote_keys = self.build_remote_transaction_keys()?;
-		let remote_initial_commitment_tx = self.build_commitment_transaction(self.cur_remote_commitment_transaction_number, &remote_keys, false, false)?.0;
-		let remote_sighash = secp_call!(Message::from_slice(&bip143::SighashComponents::new(&remote_initial_commitment_tx).sighash_all(&remote_initial_commitment_tx, 0, &funding_script, self.channel_value_satoshis)[..]));
+		let remote_initial_commitment_tx = self.build_commitment_transaction(self.cur_remote_commitment_transaction_number, &remote_keys, false, false).0;
+		let remote_sighash = Message::from_slice(&bip143::SighashComponents::new(&remote_initial_commitment_tx).sighash_all(&remote_initial_commitment_tx.input[0], &funding_script, self.channel_value_satoshis)[..]).unwrap();
 
 		let local_keys = self.build_local_transaction_keys(self.cur_local_commitment_transaction_number)?;
-		let local_initial_commitment_tx = self.build_commitment_transaction(self.cur_local_commitment_transaction_number, &local_keys, true, false)?.0;
-		let local_sighash = secp_call!(Message::from_slice(&bip143::SighashComponents::new(&local_initial_commitment_tx).sighash_all(&local_initial_commitment_tx, 0, &funding_script, self.channel_value_satoshis)[..]));
+		let local_initial_commitment_tx = self.build_commitment_transaction(self.cur_local_commitment_transaction_number, &local_keys, true, false).0;
+		let local_sighash = Message::from_slice(&bip143::SighashComponents::new(&local_initial_commitment_tx).sighash_all(&local_initial_commitment_tx.input[0], &funding_script, self.channel_value_satoshis)[..]).unwrap();
 
 		// They sign the "local" commitment transaction, allowing us to broadcast the tx if we wish.
-		secp_call!(self.secp_ctx.verify(&local_sighash, &sig, &self.their_funding_pubkey));
+		secp_call!(self.secp_ctx.verify(&local_sighash, &sig, &self.their_funding_pubkey), "Invalid funding_created signature from peer");
 
 		// We sign the "remote" commitment transaction, allowing them to broadcast the tx if they wish.
-		Ok((remote_initial_commitment_tx, secp_call!(self.secp_ctx.sign(&remote_sighash, &self.local_keys.funding_key))))
+		Ok((remote_initial_commitment_tx, self.secp_ctx.sign(&remote_sighash, &self.local_keys.funding_key).unwrap()))
 	}
 
-	pub fn funding_created(&mut self, msg: &msgs::FundingCreated) -> Result<msgs::FundingSigned, HandleError> {
+	pub fn funding_created(&mut self, msg: &msgs::FundingCreated) -> Result<(msgs::FundingSigned, ChannelMonitor), HandleError> {
 		if self.channel_outbound {
 			return Err(HandleError{err: "Received funding_created for an outbound channel?", msg: None});
 		}
@@ -902,10 +1151,11 @@ impl Channel {
 			panic!("Should not have advanced channel commitment tx numbers prior to funding_created");
 		}
 
-		self.channel_monitor.set_funding_info(msg.funding_txid, msg.funding_output_index);
+		let funding_info = OutPoint::new(msg.funding_txid, msg.funding_output_index);
+		self.channel_monitor.set_funding_info(funding_info);
 
 		let (remote_initial_commitment_tx, our_signature) = match self.funding_created_signature(&msg.signature) {
-			Ok((remote_initial_commitment_tx, sig)) => (remote_initial_commitment_tx, sig),
+			Ok(res) => res,
 			Err(e) => {
 				self.channel_monitor.unset_funding_info();
 				return Err(e);
@@ -914,73 +1164,90 @@ impl Channel {
 
 		// Now that we're past error-generating stuff, update our local state:
 
-		//TODO: Determine which tx index in remote_initial_commitment_transaction's outputs
-		//represent a revokeable script!
-		self.channel_monitor.provide_tx_info(&remote_initial_commitment_tx, 0, Vec::new());
+		self.channel_monitor.provide_latest_remote_commitment_tx_info(&remote_initial_commitment_tx, Vec::new(), self.cur_remote_commitment_transaction_number);
 		self.channel_state = ChannelState::FundingSent as u32;
 		let funding_txo = self.channel_monitor.get_funding_txo().unwrap();
-		self.channel_id = funding_txo.0.into_be() ^ Uint256::from_u64(funding_txo.1 as u64).unwrap(); //TODO: or le?
+		self.channel_id = funding_txo.to_channel_id();
+		self.cur_remote_commitment_transaction_number -= 1;
+		self.cur_local_commitment_transaction_number -= 1;
 
-		Ok(msgs::FundingSigned {
+		Ok((msgs::FundingSigned {
 			channel_id: self.channel_id,
 			signature: our_signature
-		})
+		}, self.channel_monitor.clone()))
 	}
 
 	/// 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(&mut self, msg: &msgs::FundingSigned) -> Result<(), HandleError> {
+	pub fn funding_signed(&mut self, msg: &msgs::FundingSigned) -> Result<ChannelMonitor, HandleError> {
 		if !self.channel_outbound {
 			return Err(HandleError{err: "Received funding_signed for an inbound channel?", msg: None});
 		}
 		if self.channel_state != ChannelState::FundingCreated as u32 {
 			return Err(HandleError{err: "Received funding_signed in strange state!", msg: None});
 		}
-		if self.channel_monitor.get_min_seen_secret() != (1 << 48) || self.cur_remote_commitment_transaction_number != (1 << 48) - 1 || self.cur_local_commitment_transaction_number != (1 << 48) - 1 {
+		if self.channel_monitor.get_min_seen_secret() != (1 << 48) || self.cur_remote_commitment_transaction_number != (1 << 48) - 2 || self.cur_local_commitment_transaction_number != (1 << 48) - 1 {
 			panic!("Should not have advanced channel commitment tx numbers prior to funding_created");
 		}
 
 		let funding_script = self.get_funding_redeemscript();
 
 		let local_keys = self.build_local_transaction_keys(self.cur_local_commitment_transaction_number)?;
-		let local_initial_commitment_tx = self.build_commitment_transaction(self.cur_local_commitment_transaction_number, &local_keys, true, false)?.0;
-		let local_sighash = secp_call!(Message::from_slice(&bip143::SighashComponents::new(&local_initial_commitment_tx).sighash_all(&local_initial_commitment_tx, 0, &funding_script, self.channel_value_satoshis)[..]));
+		let mut local_initial_commitment_tx = self.build_commitment_transaction(self.cur_local_commitment_transaction_number, &local_keys, true, false).0;
+		let local_sighash = Message::from_slice(&bip143::SighashComponents::new(&local_initial_commitment_tx).sighash_all(&local_initial_commitment_tx.input[0], &funding_script, self.channel_value_satoshis)[..]).unwrap();
 
 		// They sign the "local" commitment transaction, allowing us to broadcast the tx if we wish.
-		secp_call!(self.secp_ctx.verify(&local_sighash, &msg.signature, &self.their_funding_pubkey));
+		secp_call!(self.secp_ctx.verify(&local_sighash, &msg.signature, &self.their_funding_pubkey), "Invalid funding_signed signature from peer");
 
+		self.sign_commitment_transaction(&mut local_initial_commitment_tx, &msg.signature);
+		self.channel_monitor.provide_latest_local_commitment_tx_info(local_initial_commitment_tx.clone(), local_keys, self.feerate_per_kw, Vec::new());
+		self.last_local_commitment_txn = vec![local_initial_commitment_tx];
 		self.channel_state = ChannelState::FundingSent as u32;
+		self.cur_local_commitment_transaction_number -= 1;
 
-		Ok(())
+		Ok(self.channel_monitor.clone())
 	}
 
 	pub fn funding_locked(&mut self, msg: &msgs::FundingLocked) -> Result<(), HandleError> {
-		if self.channel_state == ChannelState::FundingSent as u32 {
+		let non_shutdown_state = self.channel_state & (!BOTH_SIDES_SHUTDOWN_MASK);
+		if non_shutdown_state == ChannelState::FundingSent as u32 {
 			self.channel_state |= ChannelState::TheirFundingLocked as u32;
-		} else if self.channel_state == (ChannelState::FundingSent as u32 | ChannelState::OurFundingLocked as u32) {
-			self.channel_state = ChannelState::ChannelFunded as u32;
-		} else if self.channel_state < ChannelState::FundingSent as u32 {
-			return Err(HandleError{err: "Peer sent a funding_locked before we'd even been told the funding txid", msg: None});
+		} else if non_shutdown_state == (ChannelState::FundingSent as u32 | ChannelState::OurFundingLocked as u32) {
+			self.channel_state = ChannelState::ChannelFunded as u32 | (self.channel_state & BOTH_SIDES_SHUTDOWN_MASK);
+			self.channel_update_count += 1;
+		} else {
+			return Err(HandleError{err: "Peer sent a funding_locked at a strange time", msg: None});
 		}
 
-		//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 self.their_cur_commitment_point != msg.next_per_commitment_point {
-			return Err(HandleError{err: "Non-duplicate next_per_commitment_point in funding_locked", msg: None});
-		}
+		self.their_prev_commitment_point = Some(self.their_cur_commitment_point);
 		self.their_cur_commitment_point = msg.next_per_commitment_point;
 		Ok(())
 	}
 
 	/// Returns (inbound_htlc_count, outbound_htlc_count, htlc_outbound_value_msat, htlc_inbound_value_msat)
-	fn get_pending_htlc_stats(&self) -> (u32, u32, u64, u64) {
+	/// If its for a remote update check, we need to be more lax about checking against messages we
+	/// sent but they may not have received/processed before they sent this message. Further, for
+	/// our own sends, we're more conservative and even consider things they've removed against
+	/// totals, though there is little reason to outside of further avoiding any race condition
+	/// issues.
+	fn get_pending_htlc_stats(&self, for_remote_update_check: bool) -> (u32, u32, u64, u64) {
 		let mut inbound_htlc_count: u32 = 0;
 		let mut outbound_htlc_count: u32 = 0;
 		let mut htlc_outbound_value_msat = 0;
 		let mut htlc_inbound_value_msat = 0;
 		for ref htlc in self.pending_htlcs.iter() {
+			match htlc.state {
+				HTLCState::RemoteAnnounced => {},
+				HTLCState::AwaitingRemoteRevokeToAnnounce => {},
+				HTLCState::AwaitingAnnouncedRemoteRevoke => {},
+				HTLCState::LocalAnnounced => { if for_remote_update_check { continue; } },
+				HTLCState::Committed => {},
+				HTLCState::RemoteRemoved => { if for_remote_update_check { continue; } },
+				HTLCState::AwaitingRemoteRevokeToRemove => { if for_remote_update_check { continue; } },
+				HTLCState::AwaitingRemovedRemoteRevoke => { if for_remote_update_check { continue; } },
+				HTLCState::LocalRemoved => {},
+				HTLCState::LocalRemovedAwaitingCommitment => { if for_remote_update_check { continue; } },
+			}
 			if !htlc.outbound {
 				inbound_htlc_count += 1;
 				htlc_inbound_value_msat += htlc.amount_msat;
@@ -993,7 +1260,7 @@ impl Channel {
 	}
 
 	pub fn update_add_htlc(&mut self, msg: &msgs::UpdateAddHTLC, pending_forward_state: PendingForwardHTLCInfo) -> Result<(), HandleError> {
-		if (self.channel_state & (ChannelState::ChannelFunded as u32)) != (ChannelState::ChannelFunded as u32) {
+		if (self.channel_state & (ChannelState::ChannelFunded as u32 | ChannelState::RemoteShutdownSent as u32)) != (ChannelState::ChannelFunded as u32) {
 			return Err(HandleError{err: "Got add HTLC message when channel was not in an operational state", msg: None});
 		}
 		if msg.amount_msat > self.channel_value_satoshis * 1000 {
@@ -1003,7 +1270,7 @@ impl Channel {
 			return Err(HandleError{err: "Remote side tried to send less than our minimum HTLC value", msg: None});
 		}
 
-		let (inbound_htlc_count, _, htlc_outbound_value_msat, htlc_inbound_value_msat) = self.get_pending_htlc_stats();
+		let (inbound_htlc_count, _, htlc_outbound_value_msat, htlc_inbound_value_msat) = self.get_pending_htlc_stats(true);
 		if inbound_htlc_count + 1 > OUR_MAX_HTLCS as u32 {
 			return Err(HandleError{err: "Remote tried to push more than our max accepted HTLCs", msg: None});
 		}
@@ -1036,6 +1303,8 @@ impl Channel {
 			payment_hash: msg.payment_hash,
 			cltv_expiry: msg.cltv_expiry,
 			state: HTLCState::RemoteAnnounced,
+			fail_reason: None,
+			local_removed_fulfilled: false,
 			pending_forward_state: Some(pending_forward_state),
 		});
 
@@ -1043,9 +1312,9 @@ impl Channel {
 	}
 
 	/// Removes an outbound HTLC which has been commitment_signed by the remote end
-	fn remove_outbound_htlc(&mut self, htlc_id: u64, check_preimage: Option<[u8; 32]>) -> Result<HTLCOutput, HandleError> {
-		let mut found_idx = None;
-		for (idx, ref htlc) in self.pending_htlcs.iter().enumerate() {
+	#[inline]
+	fn mark_outbound_htlc_removed(&mut self, htlc_id: u64, check_preimage: Option<[u8; 32]>, fail_reason: Option<HTLCFailReason>) -> Result<[u8; 32], HandleError> {
+		for htlc in self.pending_htlcs.iter_mut() {
 			if htlc.outbound && htlc.htlc_id == htlc_id {
 				match check_preimage {
 					None => {},
@@ -1054,72 +1323,23 @@ impl Channel {
 							return Err(HandleError{err: "Remote tried to fulfill HTLC with an incorrect preimage", msg: None});
 						}
 				};
-				found_idx = Some(idx);
-				break;
-			}
-		}
-		match found_idx {
-			None => Err(HandleError{err: "Remote tried to fulfill/fail an HTLC we couldn't find", msg: None}),
-			Some(idx) => {
-				Ok(self.pending_htlcs.swap_remove(idx))
-			}
-		}
-	}
-
-	/// Used to fulfill holding_cell_htlcs when we get a remote ack (or implicitly get it by them
-	/// fulfilling or failing the last pending HTLC)
-	fn free_holding_cell_htlcs(&mut self) -> Result<Option<(Vec<msgs::UpdateAddHTLC>, msgs::CommitmentSigned)>, HandleError> {
-		if self.holding_cell_htlcs.len() != 0 {
-			let mut new_htlcs = self.holding_cell_htlcs.split_off(0);
-			let mut update_add_msgs = Vec::with_capacity(new_htlcs.len());
-			let mut err = None;
-			for new_htlc in new_htlcs.drain(..) {
-				// Note that this *can* fail, though it should be due to rather-rare conditions on
-				// fee races with adding too many outputs which push our total payments just over
-				// the limit. In case its less rare than I anticipate, we may want to revisit
-				// handling this case better and maybe fufilling some of the HTLCs while attempting
-				// to rebalance channels.
-				if self.holding_cell_htlcs.len() != 0 {
-					self.holding_cell_htlcs.push(new_htlc);
-				} else {
-					match self.send_htlc(new_htlc.amount_msat, new_htlc.payment_hash, new_htlc.cltv_expiry, new_htlc.onion_routing_packet.clone()) {
-						Ok(update_add_msg_option) => update_add_msgs.push(update_add_msg_option.unwrap()),
-						Err(e) => {
-							self.holding_cell_htlcs.push(new_htlc);
-							err = Some(e);
-						}
-					}
-				}
-			}
-			//TODO: Need to examine the type of err - if its a fee issue or similar we may want to
-			//fail it back the route, if its a temporary issue we can ignore it...
-			if update_add_msgs.len() > 0 {
-				Ok(Some((update_add_msgs, self.send_commitment()?)))
-			} else {
-				Err(err.unwrap())
-			}
-		} else {
-			Ok(None)
-		}
-	}
-
-	/// Checks if there are any LocalAnnounced HTLCs remaining and sets
-	/// ChannelState::AwaitingRemoteRevoke accordingly, possibly calling free_holding_cell_htlcs.
-	fn check_and_free_holding_cell_htlcs(&mut self) -> Result<Option<(Vec<msgs::UpdateAddHTLC>, msgs::CommitmentSigned)>, HandleError> {
-		if (self.channel_state & (ChannelState::AwaitingRemoteRevoke as u32)) == (ChannelState::AwaitingRemoteRevoke as u32) {
-			for htlc in self.pending_htlcs.iter() {
 				if htlc.state == HTLCState::LocalAnnounced {
-					return Ok(None);
+					return Err(HandleError{err: "Remote tried to fulfill HTLC before it had been committed", msg: None});
+				} else if htlc.state == HTLCState::Committed {
+					htlc.state = HTLCState::RemoteRemoved;
+					htlc.fail_reason = fail_reason;
+				} else if htlc.state == HTLCState::AwaitingRemoteRevokeToRemove || htlc.state == HTLCState::AwaitingRemovedRemoteRevoke || htlc.state == HTLCState::RemoteRemoved {
+					return Err(HandleError{err: "Remote tried to fulfill HTLC that they'd already fulfilled", msg: None});
+				} else {
+					panic!("Got a non-outbound state on an outbound HTLC");
 				}
+				return Ok(htlc.payment_hash.clone());
 			}
-			self.channel_state &= !(ChannelState::AwaitingRemoteRevoke as u32);
-			self.free_holding_cell_htlcs()
-		} else {
-			Ok(None)
 		}
+		Err(HandleError{err: "Remote tried to fulfill/fail an HTLC we couldn't find", msg: None})
 	}
 
-	pub fn update_fulfill_htlc(&mut self, msg: &msgs::UpdateFulfillHTLC) -> Result<Option<(Vec<msgs::UpdateAddHTLC>, msgs::CommitmentSigned)>, HandleError> {
+	pub fn update_fulfill_htlc(&mut self, msg: &msgs::UpdateFulfillHTLC) -> Result<ChannelMonitor, HandleError> {
 		if (self.channel_state & (ChannelState::ChannelFunded as u32)) != (ChannelState::ChannelFunded as u32) {
 			return Err(HandleError{err: "Got add HTLC message when channel was not in an operational state", msg: None});
 		}
@@ -1129,55 +1349,29 @@ impl Channel {
 		let mut payment_hash = [0; 32];
 		sha.result(&mut payment_hash);
 
-		match self.remove_outbound_htlc(msg.htlc_id, Some(payment_hash)) {
-			Err(e) => return Err(e),
-			Ok(htlc) => {
-				//TODO: Double-check that we didn't exceed some limits (or value_to_self went
-				//negative here?)
-				self.value_to_self_msat -= htlc.amount_msat;
-			}
-		}
-
-		self.check_and_free_holding_cell_htlcs()
+		self.channel_monitor.provide_payment_preimage(&payment_hash, &msg.payment_preimage);
+		self.mark_outbound_htlc_removed(msg.htlc_id, Some(payment_hash), None)?;
+		Ok(self.channel_monitor.clone())
 	}
 
-	pub fn update_fail_htlc(&mut self, msg: &msgs::UpdateFailHTLC) -> Result<([u8; 32], Option<(Vec<msgs::UpdateAddHTLC>, msgs::CommitmentSigned)>), HandleError> {
+	pub fn update_fail_htlc(&mut self, msg: &msgs::UpdateFailHTLC, fail_reason: HTLCFailReason) -> Result<[u8; 32], HandleError> {
 		if (self.channel_state & (ChannelState::ChannelFunded as u32)) != (ChannelState::ChannelFunded as u32) {
 			return Err(HandleError{err: "Got add HTLC message when channel was not in an operational state", msg: None});
 		}
 
-		let payment_hash = match self.remove_outbound_htlc(msg.htlc_id, None) {
-			Err(e) => return Err(e),
-			Ok(htlc) => {
-				//TODO: Double-check that we didn't exceed some limits (or value_to_self went
-				//negative here?)
-				htlc.payment_hash
-			}
-		};
-
-		let holding_cell_freedom = self.check_and_free_holding_cell_htlcs()?;
-		Ok((payment_hash, holding_cell_freedom))
+		self.mark_outbound_htlc_removed(msg.htlc_id, None, Some(fail_reason))
 	}
 
-	pub fn update_fail_malformed_htlc(&mut self, msg: &msgs::UpdateFailMalformedHTLC) -> Result<([u8; 32], Option<(Vec<msgs::UpdateAddHTLC>, msgs::CommitmentSigned)>), HandleError> {
+	pub fn update_fail_malformed_htlc(&mut self, msg: &msgs::UpdateFailMalformedHTLC, fail_reason: HTLCFailReason) -> Result<(), HandleError> {
 		if (self.channel_state & (ChannelState::ChannelFunded as u32)) != (ChannelState::ChannelFunded as u32) {
 			return Err(HandleError{err: "Got add HTLC message when channel was not in an operational state", msg: None});
 		}
 
-		let payment_hash = match self.remove_outbound_htlc(msg.htlc_id, None) {
-			Err(e) => return Err(e),
-			Ok(htlc) => {
-				//TODO: Double-check that we didn't exceed some limits (or value_to_self went
-				//negative here?)
-				htlc.payment_hash
-			}
-		};
-
-		let holding_cell_freedom = self.check_and_free_holding_cell_htlcs()?;
-		Ok((payment_hash, holding_cell_freedom))
+		self.mark_outbound_htlc_removed(msg.htlc_id, None, Some(fail_reason))?;
+		Ok(())
 	}
 
-	pub fn commitment_signed(&mut self, msg: &msgs::CommitmentSigned) -> Result<(msgs::RevokeAndACK, Vec<PendingForwardHTLCInfo>), HandleError> {
+	pub fn commitment_signed(&mut self, msg: &msgs::CommitmentSigned) -> Result<(msgs::RevokeAndACK, Option<msgs::CommitmentSigned>, ChannelMonitor), HandleError> {
 		if (self.channel_state & (ChannelState::ChannelFunded as u32)) != (ChannelState::ChannelFunded as u32) {
 			return Err(HandleError{err: "Got commitment signed message when channel was not in an operational state", msg: None});
 		}
@@ -1185,43 +1379,147 @@ impl Channel {
 		let funding_script = self.get_funding_redeemscript();
 
 		let local_keys = self.build_local_transaction_keys(self.cur_local_commitment_transaction_number)?;
-		let local_commitment_tx = self.build_commitment_transaction(self.cur_local_commitment_transaction_number, &local_keys, true, false)?;
-		let local_sighash = secp_call!(Message::from_slice(&bip143::SighashComponents::new(&local_commitment_tx.0).sighash_all(&local_commitment_tx.0, 0, &funding_script, self.channel_value_satoshis)[..]));
-		secp_call!(self.secp_ctx.verify(&local_sighash, &msg.signature, &self.their_funding_pubkey));
+		let mut local_commitment_tx = self.build_commitment_transaction(self.cur_local_commitment_transaction_number, &local_keys, true, false);
+		let local_commitment_txid = local_commitment_tx.0.txid();
+		let local_sighash = Message::from_slice(&bip143::SighashComponents::new(&local_commitment_tx.0).sighash_all(&local_commitment_tx.0.input[0], &funding_script, self.channel_value_satoshis)[..]).unwrap();
+		secp_call!(self.secp_ctx.verify(&local_sighash, &msg.signature, &self.their_funding_pubkey), "Invalid commitment tx signature from peer");
 
 		if msg.htlc_signatures.len() != local_commitment_tx.1.len() {
 			return Err(HandleError{err: "Got wrong number of HTLC signatures from remote", msg: None});
 		}
 
+		let mut new_local_commitment_txn = Vec::with_capacity(local_commitment_tx.1.len() + 1);
+		self.sign_commitment_transaction(&mut local_commitment_tx.0, &msg.signature);
+		new_local_commitment_txn.push(local_commitment_tx.0.clone());
+
+		let mut htlcs_and_sigs = Vec::with_capacity(local_commitment_tx.1.len());
 		for (idx, ref htlc) in local_commitment_tx.1.iter().enumerate() {
-			let htlc_tx = self.build_htlc_transaction(&local_commitment_tx.0.txid(), htlc, true, &local_keys)?;
-			let htlc_redeemscript = chan_utils::get_htlc_redeemscript(&htlc, &local_keys, htlc.offered);
-			let htlc_sighash = secp_call!(Message::from_slice(&bip143::SighashComponents::new(&htlc_tx).sighash_all(&htlc_tx, 0, &htlc_redeemscript, htlc.amount_msat / 1000)[..]));
-			secp_call!(self.secp_ctx.verify(&htlc_sighash, &msg.htlc_signatures[idx], &local_keys.b_htlc_key));
+			let mut htlc_tx = self.build_htlc_transaction(&local_commitment_txid, htlc, true, &local_keys);
+			let htlc_redeemscript = chan_utils::get_htlc_redeemscript(&htlc, &local_keys);
+			let htlc_sighash = Message::from_slice(&bip143::SighashComponents::new(&htlc_tx).sighash_all(&htlc_tx.input[0], &htlc_redeemscript, htlc.amount_msat / 1000)[..]).unwrap();
+			secp_call!(self.secp_ctx.verify(&htlc_sighash, &msg.htlc_signatures[idx], &local_keys.b_htlc_key), "Invalid HTLC tx siganture from peer");
+			let htlc_sig = if htlc.offered {
+				let htlc_sig = self.sign_htlc_transaction(&mut htlc_tx, &msg.htlc_signatures[idx], &None, htlc, &local_keys)?;
+				new_local_commitment_txn.push(htlc_tx);
+				htlc_sig
+			} else {
+				self.create_htlc_tx_signature(&htlc_tx, htlc, &local_keys)?.1
+			};
+			htlcs_and_sigs.push(((*htlc).clone(), msg.htlc_signatures[idx], htlc_sig));
 		}
 
-		let next_per_commitment_point = PublicKey::from_secret_key(&self.secp_ctx, &self.build_local_commitment_secret(self.cur_local_commitment_transaction_number - 1)?).unwrap();
-		let per_commitment_secret = chan_utils::build_commitment_secret(self.local_keys.commitment_seed, self.cur_local_commitment_transaction_number);
-
-		//TODO: Store htlc keys in our channel_watcher
+		let next_per_commitment_point = PublicKey::from_secret_key(&self.secp_ctx, &self.build_local_commitment_secret(self.cur_local_commitment_transaction_number - 1)).unwrap();
+		let per_commitment_secret = chan_utils::build_commitment_secret(self.local_keys.commitment_seed, self.cur_local_commitment_transaction_number + 1);
 
 		// Update state now that we've passed all the can-fail calls...
+		self.channel_monitor.provide_latest_local_commitment_tx_info(local_commitment_tx.0, local_keys, self.feerate_per_kw, htlcs_and_sigs);
 
-		let mut to_forward_infos = Vec::new();
-		for ref mut htlc in self.pending_htlcs.iter_mut() {
+		let mut need_our_commitment = false;
+		for htlc in self.pending_htlcs.iter_mut() {
 			if htlc.state == HTLCState::RemoteAnnounced {
-				htlc.state = HTLCState::Committed;
-				to_forward_infos.push(htlc.pending_forward_state.take().unwrap());
+				htlc.state = HTLCState::AwaitingRemoteRevokeToAnnounce;
+				need_our_commitment = true;
+			} else if htlc.state == HTLCState::RemoteRemoved {
+				htlc.state = HTLCState::AwaitingRemoteRevokeToRemove;
+				need_our_commitment = true;
 			}
 		}
+		// Finally delete all the LocalRemovedAwaitingCommitment HTLCs
+		// We really shouldnt have two passes here, but retain gives a non-mutable ref (Rust bug)
+		let mut claimed_value_msat = 0;
+		self.pending_htlcs.retain(|htlc| {
+			if htlc.state == HTLCState::LocalRemovedAwaitingCommitment {
+				claimed_value_msat += htlc.amount_msat;
+				false
+			} else { true }
+		});
+		self.value_to_self_msat += claimed_value_msat;
 
 		self.cur_local_commitment_transaction_number -= 1;
+		self.last_local_commitment_txn = new_local_commitment_txn;
+
+		let (our_commitment_signed, monitor_update) = if need_our_commitment && (self.channel_state & (ChannelState::AwaitingRemoteRevoke as u32)) == 0 {
+			// If we're AwaitingRemoteRevoke we can't send a new commitment here, but that's ok -
+			// we'll send one right away when we get the revoke_and_ack when we
+			// free_holding_cell_htlcs().
+			let (msg, monitor) = self.send_commitment_no_status_check()?;
+			(Some(msg), monitor)
+		} else { (None, self.channel_monitor.clone()) };
 
 		Ok((msgs::RevokeAndACK {
 			channel_id: self.channel_id,
 			per_commitment_secret: per_commitment_secret,
 			next_per_commitment_point: next_per_commitment_point,
-		}, to_forward_infos))
+		}, our_commitment_signed, monitor_update))
+	}
+
+	/// Used to fulfill holding_cell_htlcs when we get a remote ack (or implicitly get it by them
+	/// fulfilling or failing the last pending HTLC)
+	fn free_holding_cell_htlcs(&mut self) -> Result<Option<(msgs::CommitmentUpdate, ChannelMonitor)>, HandleError> {
+		if self.holding_cell_htlc_updates.len() != 0 {
+			let mut htlc_updates = Vec::new();
+			mem::swap(&mut htlc_updates, &mut self.holding_cell_htlc_updates);
+			let mut update_add_htlcs = Vec::with_capacity(htlc_updates.len());
+			let mut update_fulfill_htlcs = Vec::with_capacity(htlc_updates.len());
+			let mut update_fail_htlcs = Vec::with_capacity(htlc_updates.len());
+			let mut err = None;
+			for htlc_update in htlc_updates.drain(..) {
+				// Note that this *can* fail, though it should be due to rather-rare conditions on
+				// fee races with adding too many outputs which push our total payments just over
+				// the limit. In case its less rare than I anticipate, we may want to revisit
+				// handling this case better and maybe fufilling some of the HTLCs while attempting
+				// to rebalance channels.
+				if err.is_some() { // We're back to AwaitingRemoteRevoke (or are about to fail the channel)
+					self.holding_cell_htlc_updates.push(htlc_update);
+				} else {
+					match &htlc_update {
+						&HTLCUpdateAwaitingACK::AddHTLC {amount_msat, cltv_expiry, payment_hash, ref onion_routing_packet, ..} => {
+							match self.send_htlc(amount_msat, payment_hash, cltv_expiry, onion_routing_packet.clone()) {
+								Ok(update_add_msg_option) => update_add_htlcs.push(update_add_msg_option.unwrap()),
+								Err(e) => {
+									err = Some(e);
+								}
+							}
+						},
+						&HTLCUpdateAwaitingACK::ClaimHTLC { payment_preimage, .. } => {
+							match self.get_update_fulfill_htlc(payment_preimage) {
+								Ok(update_fulfill_msg_option) => update_fulfill_htlcs.push(update_fulfill_msg_option.unwrap().0),
+								Err(e) => {
+									err = Some(e);
+								}
+							}
+						},
+						&HTLCUpdateAwaitingACK::FailHTLC { payment_hash, ref err_packet } => {
+							match self.get_update_fail_htlc(&payment_hash, err_packet.clone()) {
+								Ok(update_fail_msg_option) => update_fail_htlcs.push(update_fail_msg_option.unwrap()),
+								Err(e) => {
+									err = Some(e);
+								}
+							}
+						},
+					}
+					if err.is_some() {
+						self.holding_cell_htlc_updates.push(htlc_update);
+					}
+				}
+			}
+			//TODO: Need to examine the type of err - if its a fee issue or similar we may want to
+			//fail it back the route, if its a temporary issue we can ignore it...
+			match err {
+				None => {
+					let (commitment_signed, monitor_update) = self.send_commitment_no_status_check()?;
+					Ok(Some((msgs::CommitmentUpdate {
+						update_add_htlcs,
+						update_fulfill_htlcs,
+						update_fail_htlcs,
+						commitment_signed,
+					}, monitor_update)))
+				},
+				Some(e) => Err(e)
+			}
+		} else {
+			Ok(None)
+		}
 	}
 
 	/// Handles receiving a remote's revoke_and_ack. Note that we may return a new
@@ -1229,40 +1527,277 @@ impl Channel {
 	/// waiting on this revoke_and_ack. The generation of this new commitment_signed may also fail,
 	/// generating an appropriate error *after* the channel state has been updated based on the
 	/// revoke_and_ack message.
-	pub fn revoke_and_ack(&mut self, msg: &msgs::RevokeAndACK) -> Result<Option<(Vec<msgs::UpdateAddHTLC>, msgs::CommitmentSigned)>, HandleError> {
+	pub fn revoke_and_ack(&mut self, msg: &msgs::RevokeAndACK) -> Result<(Option<msgs::CommitmentUpdate>, Vec<PendingForwardHTLCInfo>, Vec<([u8; 32], HTLCFailReason)>, ChannelMonitor), HandleError> {
 		if (self.channel_state & (ChannelState::ChannelFunded as u32)) != (ChannelState::ChannelFunded as u32) {
 			return Err(HandleError{err: "Got revoke/ACK message when channel was not in an operational state", msg: None});
 		}
-		if PublicKey::from_secret_key(&self.secp_ctx, &get_key!(&self.secp_ctx, &msg.per_commitment_secret)).unwrap() != self.their_cur_commitment_point {
-			return Err(HandleError{err: "Got a revoke commitment secret which didn't correspond to their current pubkey", msg: None});
+		if let Some(their_prev_commitment_point) = self.their_prev_commitment_point {
+			if PublicKey::from_secret_key(&self.secp_ctx, &secp_call!(SecretKey::from_slice(&self.secp_ctx, &msg.per_commitment_secret), "Peer provided an invalid per_commitment_secret")).unwrap() != their_prev_commitment_point {
+				return Err(HandleError{err: "Got a revoke commitment secret which didn't correspond to their current pubkey", msg: None});
+			}
 		}
-		self.channel_monitor.provide_secret(self.cur_remote_commitment_transaction_number, msg.per_commitment_secret)?;
+		self.channel_monitor.provide_secret(self.cur_remote_commitment_transaction_number + 1, msg.per_commitment_secret, Some((self.cur_remote_commitment_transaction_number - 1, msg.next_per_commitment_point)))?;
 
 		// Update state now that we've passed all the can-fail calls...
 		// (note that we may still fail to generate the new commitment_signed message, but that's
 		// OK, we step the channel here and *then* if the new generation fails we can fail the
 		// channel based on that, but stepping stuff here should be safe either way.
 		self.channel_state &= !(ChannelState::AwaitingRemoteRevoke as u32);
+		self.their_prev_commitment_point = Some(self.their_cur_commitment_point);
 		self.their_cur_commitment_point = msg.next_per_commitment_point;
 		self.cur_remote_commitment_transaction_number -= 1;
+
+		let mut to_forward_infos = Vec::new();
+		let mut revoked_htlcs = Vec::new();
+		let mut require_commitment = false;
+		let mut value_to_self_msat_diff: i64 = 0;
+		// We really shouldnt have two passes here, but retain gives a non-mutable ref (Rust bug)
+		self.pending_htlcs.retain(|htlc| {
+			if htlc.state == HTLCState::LocalRemoved {
+				if htlc.local_removed_fulfilled { true } else { false }
+			} else if htlc.state == HTLCState::AwaitingRemovedRemoteRevoke {
+				if let Some(reason) = htlc.fail_reason.clone() { // We really want take() here, but, again, non-mut ref :(
+					revoked_htlcs.push((htlc.payment_hash, reason));
+				} else {
+					// They fulfilled, so we sent them money
+					value_to_self_msat_diff -= htlc.amount_msat as i64;
+				}
+				false
+			} else { true }
+		});
 		for htlc in self.pending_htlcs.iter_mut() {
 			if htlc.state == HTLCState::LocalAnnounced {
 				htlc.state = HTLCState::Committed;
+			} else if htlc.state == HTLCState::AwaitingRemoteRevokeToAnnounce {
+				htlc.state = HTLCState::AwaitingAnnouncedRemoteRevoke;
+				require_commitment = true;
+			} else if htlc.state == HTLCState::AwaitingAnnouncedRemoteRevoke {
+				htlc.state = HTLCState::Committed;
+				to_forward_infos.push(htlc.pending_forward_state.take().unwrap());
+			} else if htlc.state == HTLCState::AwaitingRemoteRevokeToRemove {
+				htlc.state = HTLCState::AwaitingRemovedRemoteRevoke;
+				require_commitment = true;
+			} else if htlc.state == HTLCState::LocalRemoved {
+				assert!(htlc.local_removed_fulfilled);
+				htlc.state = HTLCState::LocalRemovedAwaitingCommitment;
+			}
+		}
+		self.value_to_self_msat = (self.value_to_self_msat as i64 + value_to_self_msat_diff) as u64;
+
+		match self.free_holding_cell_htlcs()? {
+			Some(commitment_update) => {
+				Ok((Some(commitment_update.0), to_forward_infos, revoked_htlcs, commitment_update.1))
+			},
+			None => {
+				if require_commitment {
+					let (commitment_signed, monitor_update) = self.send_commitment_no_status_check()?;
+					Ok((Some(msgs::CommitmentUpdate {
+						update_add_htlcs: Vec::new(),
+						update_fulfill_htlcs: Vec::new(),
+						update_fail_htlcs: Vec::new(),
+						commitment_signed
+					}), to_forward_infos, revoked_htlcs, monitor_update))
+				} else {
+					Ok((None, to_forward_infos, revoked_htlcs, self.channel_monitor.clone()))
+				}
 			}
 		}
-
-		self.free_holding_cell_htlcs()
 	}
 
 	pub fn update_fee(&mut self, fee_estimator: &FeeEstimator, msg: &msgs::UpdateFee) -> Result<(), HandleError> {
-        if self.channel_outbound {
+		if self.channel_outbound {
 			return Err(HandleError{err: "Non-funding remote tried to update channel fee", msg: None});
-        }
-		Channel::check_remote_fee(fee_estimator, msg.feerate_per_kw).unwrap();
+		}
+		Channel::check_remote_fee(fee_estimator, msg.feerate_per_kw)?;
+		self.channel_update_count += 1;
 		self.feerate_per_kw = msg.feerate_per_kw as u64;
 		Ok(())
 	}
 
+	pub fn shutdown(&mut self, fee_estimator: &FeeEstimator, msg: &msgs::Shutdown) -> Result<(Option<msgs::Shutdown>, Option<msgs::ClosingSigned>, Vec<[u8; 32]>), HandleError> {
+		if self.channel_state < ChannelState::FundingSent as u32 {
+			self.channel_state = ChannelState::ShutdownComplete as u32;
+			self.channel_update_count += 1;
+			return Ok((None, None, Vec::new()));
+		}
+		for htlc in self.pending_htlcs.iter() {
+			if htlc.state == HTLCState::RemoteAnnounced {
+				return Err(HandleError{err: "Got shutdown with remote pending HTLCs", msg: None});
+			}
+		}
+		if (self.channel_state & ChannelState::RemoteShutdownSent as u32) == ChannelState::RemoteShutdownSent as u32 {
+			return Err(HandleError{err: "Remote peer sent duplicate shutdown message", msg: None});
+		}
+		assert_eq!(self.channel_state & ChannelState::ShutdownComplete as u32, 0);
+
+		// BOLT 2 says we must only send a scriptpubkey of certain standard forms, which are up to
+		// 34 bytes in length, so dont let the remote peer feed us some super fee-heavy script.
+		if self.channel_outbound && msg.scriptpubkey.len() > 34 {
+			return Err(HandleError{err: "Got shutdown_scriptpubkey of absurd length from remote peer", msg: None});
+		}
+		//TODO: Check shutdown_scriptpubkey form as BOLT says we must? WHYYY
+
+		if self.their_shutdown_scriptpubkey.is_some() {
+			if Some(&msg.scriptpubkey) != self.their_shutdown_scriptpubkey.as_ref() {
+				return Err(HandleError{err: "Got shutdown request with a scriptpubkey which did not match their previous scriptpubkey", msg: None});
+			}
+		} else {
+			self.their_shutdown_scriptpubkey = Some(msg.scriptpubkey.clone());
+		}
+
+		let our_closing_script = self.get_closing_scriptpubkey();
+
+		let (proposed_feerate, proposed_fee, our_sig) = if self.channel_outbound && self.pending_htlcs.is_empty() {
+			let mut proposed_feerate = fee_estimator.get_est_sat_per_vbyte(ConfirmationTarget::Background);
+			if self.feerate_per_kw > proposed_feerate * 250 {
+				proposed_feerate = self.feerate_per_kw / 250;
+			}
+			let tx_weight = Self::get_closing_transaction_weight(&our_closing_script, &msg.scriptpubkey);
+			let proposed_total_fee_satoshis = proposed_feerate * tx_weight / 4;
+
+			let (closing_tx, total_fee_satoshis) = self.build_closing_transaction(proposed_total_fee_satoshis, false);
+			let funding_redeemscript = self.get_funding_redeemscript();
+			let sighash = Message::from_slice(&bip143::SighashComponents::new(&closing_tx).sighash_all(&closing_tx.input[0], &funding_redeemscript, self.channel_value_satoshis)[..]).unwrap();
+
+			(Some(proposed_feerate), Some(total_fee_satoshis), Some(self.secp_ctx.sign(&sighash, &self.local_keys.funding_key).unwrap()))
+		} else { (None, None, None) };
+
+		// From here on out, we may not fail!
+
+		self.channel_state |= ChannelState::RemoteShutdownSent as u32;
+		self.channel_update_count += 1;
+
+		// We can't send our shutdown until we've committed all of our pending HTLCs, but the
+		// remote side is unlikely to accept any new HTLCs, so we go ahead and "free" any holding
+		// cell HTLCs and return them to fail the payment.
+		let mut dropped_outbound_htlcs = Vec::with_capacity(self.holding_cell_htlc_updates.len());
+		self.holding_cell_htlc_updates.retain(|htlc_update| {
+			match htlc_update {
+				&HTLCUpdateAwaitingACK::AddHTLC { ref payment_hash, .. } => {
+					dropped_outbound_htlcs.push(payment_hash.clone());
+					false
+				},
+				_ => true
+			}
+		});
+		for htlc in self.pending_htlcs.iter() {
+			if htlc.state == HTLCState::LocalAnnounced {
+				return Ok((None, None, dropped_outbound_htlcs));
+			}
+		}
+
+		let our_shutdown = if (self.channel_state & ChannelState::LocalShutdownSent as u32) == ChannelState::LocalShutdownSent as u32 {
+			None
+		} else {
+			Some(msgs::Shutdown {
+				channel_id: self.channel_id,
+				scriptpubkey: our_closing_script,
+			})
+		};
+
+		self.channel_state |= ChannelState::LocalShutdownSent as u32;
+		self.channel_update_count += 1;
+		if self.pending_htlcs.is_empty() && self.channel_outbound {
+			// There are no more HTLCs and we're the funder, this means we start the closing_signed
+			// dance with an initial fee proposal!
+			self.last_sent_closing_fee = Some((proposed_feerate.unwrap(), proposed_fee.unwrap()));
+			Ok((our_shutdown, Some(msgs::ClosingSigned {
+				channel_id: self.channel_id,
+				fee_satoshis: proposed_fee.unwrap(),
+				signature: our_sig.unwrap(),
+			}), dropped_outbound_htlcs))
+		} else {
+			Ok((our_shutdown, None, dropped_outbound_htlcs))
+		}
+	}
+
+	pub fn closing_signed(&mut self, fee_estimator: &FeeEstimator, msg: &msgs::ClosingSigned) -> Result<(Option<msgs::ClosingSigned>, Option<Transaction>), HandleError> {
+		if self.channel_state & BOTH_SIDES_SHUTDOWN_MASK != BOTH_SIDES_SHUTDOWN_MASK {
+			return Err(HandleError{err: "Remote end sent us a closing_signed before both sides provided a shutdown", msg: None});
+		}
+		if !self.pending_htlcs.is_empty() {
+			return Err(HandleError{err: "Remote end sent us a closing_signed while there were still pending HTLCs", msg: None});
+		}
+		if msg.fee_satoshis > 21000000 * 10000000 {
+			return Err(HandleError{err: "Remote tried to send us a closing tx with > 21 million BTC fee", msg: None});
+		}
+
+		let funding_redeemscript = self.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(HandleError{err: "Remote sent us a closing_signed with a fee greater than the value they can claim", msg: None});
+		}
+		let mut sighash = Message::from_slice(&bip143::SighashComponents::new(&closing_tx).sighash_all(&closing_tx.input[0], &funding_redeemscript, self.channel_value_satoshis)[..]).unwrap();
+
+		match self.secp_ctx.verify(&sighash, &msg.signature, &self.their_funding_pubkey) {
+			Ok(_) => {},
+			Err(_) => {
+				// The remote end may have decided to revoke their output due to inconsistent dust
+				// limits, so check for that case by re-checking the signature here.
+				closing_tx = self.build_closing_transaction(msg.fee_satoshis, true).0;
+				sighash = Message::from_slice(&bip143::SighashComponents::new(&closing_tx).sighash_all(&closing_tx.input[0], &funding_redeemscript, self.channel_value_satoshis)[..]).unwrap();
+				secp_call!(self.secp_ctx.verify(&sighash, &msg.signature, &self.their_funding_pubkey), "Invalid closing tx signature from peer");
+			},
+		};
+
+		if let Some((_, last_fee)) = self.last_sent_closing_fee {
+			if last_fee == msg.fee_satoshis {
+				self.sign_commitment_transaction(&mut closing_tx, &msg.signature);
+				self.channel_state = ChannelState::ShutdownComplete as u32;
+				self.channel_update_count += 1;
+				return Ok((None, Some(closing_tx)));
+			}
+		}
+
+		macro_rules! propose_new_feerate {
+			($new_feerate: expr) => {
+				let closing_tx_max_weight = Self::get_closing_transaction_weight(&self.get_closing_scriptpubkey(), self.their_shutdown_scriptpubkey.as_ref().unwrap());
+				let (closing_tx, used_total_fee) = self.build_closing_transaction($new_feerate * closing_tx_max_weight / 4, false);
+				sighash = Message::from_slice(&bip143::SighashComponents::new(&closing_tx).sighash_all(&closing_tx.input[0], &funding_redeemscript, self.channel_value_satoshis)[..]).unwrap();
+				let our_sig = self.secp_ctx.sign(&sighash, &self.local_keys.funding_key).unwrap();
+				self.last_sent_closing_fee = Some(($new_feerate, used_total_fee));
+				return Ok((Some(msgs::ClosingSigned {
+					channel_id: self.channel_id,
+					fee_satoshis: used_total_fee,
+					signature: our_sig,
+				}), None))
+			}
+		}
+
+		let proposed_sat_per_vbyte = msg.fee_satoshis * 4 / closing_tx.get_weight();
+		if self.channel_outbound {
+			let our_max_feerate = fee_estimator.get_est_sat_per_vbyte(ConfirmationTarget::Normal);
+			if proposed_sat_per_vbyte > our_max_feerate {
+				if let Some((last_feerate, _)) = self.last_sent_closing_fee {
+					if our_max_feerate <= last_feerate {
+						return Err(HandleError{err: "Unable to come to consensus about closing feerate, remote wanted something higher than our Normal feerate", msg: None});
+					}
+				}
+				propose_new_feerate!(our_max_feerate);
+			}
+		} else {
+			let our_min_feerate = fee_estimator.get_est_sat_per_vbyte(ConfirmationTarget::Background);
+			if proposed_sat_per_vbyte < our_min_feerate {
+				if let Some((last_feerate, _)) = self.last_sent_closing_fee {
+					if our_min_feerate >= last_feerate {
+						return Err(HandleError{err: "Unable to come to consensus about closing feerate, remote wanted something lower than our Background feerate", msg: None});
+					}
+				}
+				propose_new_feerate!(our_min_feerate);
+			}
+		}
+
+		let our_sig = self.sign_commitment_transaction(&mut closing_tx, &msg.signature);
+		self.channel_state = ChannelState::ShutdownComplete as u32;
+		self.channel_update_count += 1;
+
+		Ok((Some(msgs::ClosingSigned {
+			channel_id: self.channel_id,
+			fee_satoshis: msg.fee_satoshis,
+			signature: our_sig,
+		}), Some(closing_tx)))
+	}
+
 	// Public utilities:
 
 	pub fn channel_id(&self) -> Uint256 {
@@ -1275,6 +1810,13 @@ impl Channel {
 		self.user_id
 	}
 
+	pub fn channel_monitor(&self) -> ChannelMonitor {
+		if self.channel_state < ChannelState::FundingCreated as u32 {
+			panic!("Can't get a channel monitor until funding has been created");
+		}
+		self.channel_monitor.clone()
+	}
+
 	/// Guaranteed to be Some after both FundingLocked messages have been exchanged (and, thus,
 	/// is_usable() returns true).
 	pub fn get_short_channel_id(&self) -> Option<u64> {
@@ -1283,7 +1825,7 @@ impl Channel {
 
 	/// Returns the funding_txo we either got from our peer, or were given by
 	/// get_outbound_funding_created.
-	pub fn get_funding_txo(&self) -> Option<(Sha256dHash, u16)> {
+	pub fn get_funding_txo(&self) -> Option<OutPoint> {
 		self.channel_monitor.get_funding_txo()
 	}
 
@@ -1299,8 +1841,7 @@ impl Channel {
 		self.channel_value_satoshis
 	}
 
-	pub fn get_channel_update_count(&mut self) -> u32 {
-		self.channel_update_count += 1; //TODO: This should be base on updates, not updates *sent*
+	pub fn get_channel_update_count(&self) -> u32 {
 		self.channel_update_count
 	}
 
@@ -1323,16 +1864,10 @@ impl Channel {
 		res as u32
 	}
 
-	pub fn channel_monitor(&self) -> ChannelMonitor {
-		if self.channel_state < ChannelState::FundingCreated as u32 {
-			panic!("Can't get a channel monitor until funding has been created");
-		}
-		self.channel_monitor.clone()
-	}
-
 	/// Returns true if this channel is fully established and not known to be closing.
 	pub fn is_usable(&self) -> bool {
-		(self.channel_state & (ChannelState::ChannelFunded as u32)) == (ChannelState::ChannelFunded as u32)
+		let mask = ChannelState::ChannelFunded as u32 | BOTH_SIDES_SHUTDOWN_MASK;
+		(self.channel_state & mask) == (ChannelState::ChannelFunded as u32)
 	}
 
 	/// Returns true if this channel is currently available for use. This is a superset of
@@ -1341,19 +1876,31 @@ impl Channel {
 		self.is_usable()
 	}
 
+	/// Returns true if this channel is fully shut down. True here implies that no further actions
+	/// may/will be taken on this channel, and thus this object should be freed. Any future changes
+	/// will be handled appropriately by the chain monitor.
+	pub fn is_shutdown(&self) -> bool {
+		if (self.channel_state & ChannelState::ShutdownComplete as u32) == ChannelState::ShutdownComplete as u32  {
+			assert!(self.channel_state == ChannelState::ShutdownComplete as u32);
+			true
+		} else { false }
+	}
+
 	/// Called by channelmanager based on chain blocks being connected.
 	/// Note that we only need to use this to detect funding_signed, anything else is handled by
 	/// the channel_monitor.
 	pub fn block_connected(&mut self, header: &BlockHeader, height: u32, txn_matched: &[&Transaction], indexes_of_txn_matched: &[u32]) -> Option<msgs::FundingLocked> {
+		let non_shutdown_state = self.channel_state & (!BOTH_SIDES_SHUTDOWN_MASK);
 		if self.funding_tx_confirmations > 0 {
 			if header.bitcoin_hash() != self.last_block_connected {
 				self.last_block_connected = header.bitcoin_hash();
 				self.funding_tx_confirmations += 1;
 				if self.funding_tx_confirmations == CONF_TARGET as u64 {
-					if self.channel_state == ChannelState::FundingSent as u32 {
+					if non_shutdown_state == ChannelState::FundingSent as u32 {
 						self.channel_state |= ChannelState::OurFundingLocked as u32;
-					} else if self.channel_state == (ChannelState::FundingSent as u32 | ChannelState::TheirFundingLocked as u32) {
-						self.channel_state = ChannelState::ChannelFunded as u32;
+					} else if non_shutdown_state == (ChannelState::FundingSent as u32 | ChannelState::TheirFundingLocked as u32) {
+						self.channel_state = ChannelState::ChannelFunded as u32 | (self.channel_state & BOTH_SIDES_SHUTDOWN_MASK);
+						self.channel_update_count += 1;
 						//TODO: Something about a state where we "lost confirmation"
 					} else if self.channel_state < ChannelState::ChannelFunded as u32 {
 						panic!("Started confirming a channel in a state pre-FundingSent?");
@@ -1364,11 +1911,7 @@ impl Channel {
 					//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.
-					let next_per_commitment_secret = match self.build_local_commitment_secret(self.cur_local_commitment_transaction_number) {
-						Ok(secret) => secret,
-						Err(_) => return None
-					};
-
+					let next_per_commitment_secret = self.build_local_commitment_secret(self.cur_local_commitment_transaction_number);
 					let next_per_commitment_point = PublicKey::from_secret_key(&self.secp_ctx, &next_per_commitment_secret).unwrap();
 					return Some(msgs::FundingLocked {
 						channel_id: self.channel_id,
@@ -1377,13 +1920,20 @@ impl Channel {
 				}
 			}
 		}
-		if self.channel_state & !(ChannelState::TheirFundingLocked as u32) == ChannelState::FundingSent as u32 {
+		if non_shutdown_state & !(ChannelState::TheirFundingLocked as u32) == ChannelState::FundingSent as u32 {
 			for (ref tx, index_in_block) in txn_matched.iter().zip(indexes_of_txn_matched) {
-				if tx.txid() == self.channel_monitor.get_funding_txo().unwrap().0 {
-					self.funding_tx_confirmations = 1;
-					self.short_channel_id = Some(((height as u64)          << (5*8)) |
-					                             ((*index_in_block as u64) << (2*8)) |
-					                             ((self.channel_monitor.get_funding_txo().unwrap().1 as u64) << (2*8)));
+				if tx.txid() == self.channel_monitor.get_funding_txo().unwrap().txid {
+					let txo_idx = self.channel_monitor.get_funding_txo().unwrap().index as usize;
+					if txo_idx >= tx.output.len() || tx.output[txo_idx].script_pubkey != self.get_funding_redeemscript().to_v0_p2wsh() ||
+						tx.output[txo_idx].value != self.channel_value_satoshis {
+						self.channel_state = ChannelState::ShutdownComplete as u32;
+						self.channel_update_count += 1;
+					} else {
+						self.funding_tx_confirmations = 1;
+						self.short_channel_id = Some(((height as u64)		   << (5*8)) |
+						                             ((*index_in_block as u64) << (2*8)) |
+						                             ((self.channel_monitor.get_funding_txo().unwrap().index as u64) << (2*8)));
+					}
 				}
 			}
 		}
@@ -1421,7 +1971,7 @@ impl Channel {
 			panic!("Tried to send an open_channel for a channel that has already advanced");
 		}
 
-		let local_commitment_secret = self.build_local_commitment_secret(self.cur_local_commitment_transaction_number)?;
+		let local_commitment_secret = self.build_local_commitment_secret(self.cur_local_commitment_transaction_number);
 
 		Ok(msgs::OpenChannel {
 			chain_hash: chain_hash,
@@ -1457,7 +2007,7 @@ impl Channel {
 			panic!("Tried to send an accept_channel for a channel that has already advanced");
 		}
 
-		let local_commitment_secret = self.build_local_commitment_secret(self.cur_local_commitment_transaction_number)?;
+		let local_commitment_secret = self.build_local_commitment_secret(self.cur_local_commitment_transaction_number);
 
 		Ok(msgs::AcceptChannel {
 			temporary_channel_id: self.channel_id,
@@ -1478,15 +2028,15 @@ impl Channel {
 		})
 	}
 
-	fn get_outbound_funding_created_signature(&mut self) -> Result<Signature, HandleError> {
+	fn get_outbound_funding_created_signature(&mut self) -> Result<(Signature, Transaction), HandleError> {
 		let funding_script = self.get_funding_redeemscript();
 
 		let remote_keys = self.build_remote_transaction_keys()?;
-		let remote_initial_commitment_tx = self.build_commitment_transaction(self.cur_remote_commitment_transaction_number, &remote_keys, false, false)?.0;
-		let remote_sighash = secp_call!(Message::from_slice(&bip143::SighashComponents::new(&remote_initial_commitment_tx).sighash_all(&remote_initial_commitment_tx, 0, &funding_script, self.channel_value_satoshis)[..]));
+		let remote_initial_commitment_tx = self.build_commitment_transaction(self.cur_remote_commitment_transaction_number, &remote_keys, false, false).0;
+		let remote_sighash = Message::from_slice(&bip143::SighashComponents::new(&remote_initial_commitment_tx).sighash_all(&remote_initial_commitment_tx.input[0], &funding_script, self.channel_value_satoshis)[..]).unwrap();
 
 		// We sign the "remote" commitment transaction, allowing them to broadcast the tx if they wish.
-		Ok(secp_call!(self.secp_ctx.sign(&remote_sighash, &self.local_keys.funding_key)))
+		Ok((self.secp_ctx.sign(&remote_sighash, &self.local_keys.funding_key).unwrap(), remote_initial_commitment_tx))
 	}
 
 	/// Updates channel state with knowledge of the funding transaction's txid/index, and generates
@@ -1495,7 +2045,7 @@ impl Channel {
 	/// or if called on an inbound channel.
 	/// Note that channel_id changes during this call!
 	/// Do NOT broadcast the funding transaction until after a successful funding_signed call!
-	pub fn get_outbound_funding_created(&mut self, funding_txid: Sha256dHash, funding_output_index: u16) -> Result<msgs::FundingCreated, HandleError> {
+	pub fn get_outbound_funding_created(&mut self, funding_txo: OutPoint) -> Result<(msgs::FundingCreated, ChannelMonitor), HandleError> {
 		if !self.channel_outbound {
 			panic!("Tried to create outbound funding_created message on an inbound channel!");
 		}
@@ -1506,10 +2056,10 @@ impl Channel {
 			panic!("Should not have advanced channel commitment tx numbers prior to funding_created");
 		}
 
-		self.channel_monitor.set_funding_info(funding_txid, funding_output_index);
+		self.channel_monitor.set_funding_info(funding_txo);
 
-		let our_signature = match self.get_outbound_funding_created_signature() {
-			Ok(sig) => sig,
+		let (our_signature, commitment_tx) = match self.get_outbound_funding_created_signature() {
+			Ok(res) => res,
 			Err(e) => {
 				self.channel_monitor.unset_funding_info();
 				return Err(e);
@@ -1519,28 +2069,32 @@ impl Channel {
 		let temporary_channel_id = self.channel_id;
 
 		// Now that we're past error-generating stuff, update our local state:
-
+		self.channel_monitor.provide_latest_remote_commitment_tx_info(&commitment_tx, Vec::new(), self.cur_remote_commitment_transaction_number);
 		self.channel_state = ChannelState::FundingCreated as u32;
 		let funding_txo = self.channel_monitor.get_funding_txo().unwrap();
-		self.channel_id = funding_txo.0.into_be() ^ Uint256::from_u64(funding_txo.1 as u64).unwrap(); //TODO: or le?
+		self.channel_id = funding_txo.to_channel_id();
+		self.cur_remote_commitment_transaction_number -= 1;
 
-		Ok(msgs::FundingCreated {
+		Ok((msgs::FundingCreated {
 			temporary_channel_id: temporary_channel_id,
-			funding_txid: funding_txid,
-			funding_output_index: funding_output_index,
+			funding_txid: funding_txo.txid,
+			funding_output_index: funding_txo.index,
 			signature: our_signature
-		})
+		}, self.channel_monitor.clone()))
 	}
 
 	/// Gets an UnsignedChannelAnnouncement, as well as a signature covering it using our
 	/// bitcoin_key, if available, for this channel. The channel must be publicly announceable and
 	/// available for use (have exchanged FundingLocked messages in both directions. Should be used
 	/// for both loose and in response to an AnnouncementSignatures message from the remote peer.
+	/// Note that you can get an announcement for a channel which is closing, though you should
+	/// likely not announce such a thing. In case its already been announced, a channel_update
+	/// message can mark the channel disabled.
 	pub fn get_channel_announcement(&self, our_node_id: PublicKey, chain_hash: Sha256dHash) -> Result<(msgs::UnsignedChannelAnnouncement, Signature), HandleError> {
 		if !self.announce_publicly {
 			return Err(HandleError{err: "Channel is not available for public announcements", msg: None});
 		}
-		if self.channel_state < ChannelState::ChannelFunded as u32 {
+		if self.channel_state & (ChannelState::ChannelFunded as u32) != (ChannelState::ChannelFunded as u32) {
 			return Err(HandleError{err: "Cannot get a ChannelAnnouncement until the channel funding has been locked", msg: None});
 		}
 
@@ -1558,7 +2112,7 @@ impl Channel {
 		};
 
 		let msghash = Message::from_slice(&Sha256dHash::from_data(&msg.encode()[..])[..]).unwrap();
-		let sig = secp_call!(self.secp_ctx.sign(&msghash, &self.local_keys.funding_key));
+		let sig = self.secp_ctx.sign(&msghash, &self.local_keys.funding_key).unwrap();
 
 		Ok((msg, sig))
 	}
@@ -1572,8 +2126,8 @@ impl Channel {
 	/// waiting on the remote peer to send us a revoke_and_ack during which time we cannot add new
 	/// HTLCs on the wire or we wouldn't be able to determine what they actually ACK'ed.
 	pub fn send_htlc(&mut self, amount_msat: u64, payment_hash: [u8; 32], cltv_expiry: u32, onion_routing_packet: msgs::OnionPacket) -> Result<Option<msgs::UpdateAddHTLC>, HandleError> {
-		if (self.channel_state & (ChannelState::ChannelFunded as u32)) != (ChannelState::ChannelFunded as u32) {
-			return Err(HandleError{err: "Cannot send HTLC until channel is fully established", msg: None});
+		if (self.channel_state & (ChannelState::ChannelFunded as u32 | BOTH_SIDES_SHUTDOWN_MASK)) != (ChannelState::ChannelFunded as u32) {
+			return Err(HandleError{err: "Cannot send HTLC until channel is fully established and we haven't started shutting down", msg: None});
 		}
 
 		if amount_msat > self.channel_value_satoshis * 1000 {
@@ -1583,7 +2137,7 @@ impl Channel {
 			return Err(HandleError{err: "Cannot send less than their minimum HTLC value", msg: None});
 		}
 
-		let (_, outbound_htlc_count, htlc_outbound_value_msat, htlc_inbound_value_msat) = self.get_pending_htlc_stats();
+		let (_, outbound_htlc_count, htlc_outbound_value_msat, htlc_inbound_value_msat) = self.get_pending_htlc_stats(false);
 		if outbound_htlc_count + 1 > self.their_max_accepted_htlcs as u32 {
 			return Err(HandleError{err: "Cannot push more than their max accepted HTLCs", msg: None});
 		}
@@ -1602,7 +2156,7 @@ impl Channel {
 		// Now update local state:
 		if (self.channel_state & (ChannelState::AwaitingRemoteRevoke as u32)) == (ChannelState::AwaitingRemoteRevoke as u32) {
 			//TODO: Check the limits *including* other pending holding cell HTLCs!
-			self.holding_cell_htlcs.push(HTLCOutputAwaitingACK {
+			self.holding_cell_htlc_updates.push(HTLCUpdateAwaitingACK::AddHTLC {
 				amount_msat: amount_msat,
 				payment_hash: payment_hash,
 				cltv_expiry: cltv_expiry,
@@ -1619,6 +2173,8 @@ impl Channel {
 			payment_hash: payment_hash.clone(),
 			cltv_expiry: cltv_expiry,
 			state: HTLCState::LocalAnnounced,
+			fail_reason: None,
+			local_removed_fulfilled: false,
 			pending_forward_state: None
 		});
 
@@ -1636,49 +2192,134 @@ impl Channel {
 	}
 
 	/// Creates a signed commitment transaction to send to the remote peer.
-	pub fn send_commitment(&mut self) -> Result<msgs::CommitmentSigned, HandleError> {
+	pub fn send_commitment(&mut self) -> Result<(msgs::CommitmentSigned, ChannelMonitor), HandleError> {
 		if (self.channel_state & (ChannelState::ChannelFunded as u32)) != (ChannelState::ChannelFunded as u32) {
 			return Err(HandleError{err: "Cannot create commitment tx until channel is fully established", msg: None});
 		}
-
+		if (self.channel_state & (ChannelState::AwaitingRemoteRevoke as u32)) == (ChannelState::AwaitingRemoteRevoke as u32) {
+			return Err(HandleError{err: "Cannot create commitment tx until remote revokes their previous commitment", msg: None});
+		}
+		let mut have_updates = false; // TODO initialize with "have we sent a fee update?"
+		for htlc in self.pending_htlcs.iter() {
+			if htlc.state == HTLCState::LocalAnnounced {
+				have_updates = true;
+			}
+			if have_updates { break; }
+		}
+		if !have_updates {
+			return Err(HandleError{err: "Cannot create commitment tx until we have some updates to send", msg: None});
+		}
+		self.send_commitment_no_status_check()
+	}
+	/// Only fails in case of bad keys
+	fn send_commitment_no_status_check(&mut self) -> Result<(msgs::CommitmentSigned, ChannelMonitor), HandleError> {
 		let funding_script = self.get_funding_redeemscript();
 
+		// We can upgrade the status of some HTLCs that are waiting on a commitment, even if we
+		// fail to generate this, we still are at least at a position where upgrading their status
+		// is acceptable.
+		for htlc in self.pending_htlcs.iter_mut() {
+			if htlc.state == HTLCState::AwaitingRemoteRevokeToAnnounce {
+				htlc.state = HTLCState::AwaitingAnnouncedRemoteRevoke;
+			} else if htlc.state == HTLCState::AwaitingRemoteRevokeToRemove {
+				htlc.state = HTLCState::AwaitingRemovedRemoteRevoke;
+			}
+		}
+
 		let remote_keys = self.build_remote_transaction_keys()?;
-		let remote_commitment_tx = self.build_commitment_transaction(self.cur_remote_commitment_transaction_number, &remote_keys, false, true)?;
-		let remote_sighash = secp_call!(Message::from_slice(&bip143::SighashComponents::new(&remote_commitment_tx.0).sighash_all(&remote_commitment_tx.0, 0, &funding_script, self.channel_value_satoshis)[..]));
-		let our_sig = secp_call!(self.secp_ctx.sign(&remote_sighash, &self.local_keys.funding_key));
+		let remote_commitment_tx = self.build_commitment_transaction(self.cur_remote_commitment_transaction_number, &remote_keys, false, true);
+		let remote_commitment_txid = remote_commitment_tx.0.txid();
+		let remote_sighash = Message::from_slice(&bip143::SighashComponents::new(&remote_commitment_tx.0).sighash_all(&remote_commitment_tx.0.input[0], &funding_script, self.channel_value_satoshis)[..]).unwrap();
+		let our_sig = self.secp_ctx.sign(&remote_sighash, &self.local_keys.funding_key).unwrap();
 
 		let mut htlc_sigs = Vec::new();
 
 		for ref htlc in remote_commitment_tx.1.iter() {
-			let htlc_tx = self.build_htlc_transaction(&remote_commitment_tx.0.txid(), htlc, false, &remote_keys)?;
-			let htlc_redeemscript = chan_utils::get_htlc_redeemscript(&htlc, &remote_keys, htlc.offered);
-			let htlc_sighash = secp_call!(Message::from_slice(&bip143::SighashComponents::new(&htlc_tx).sighash_all(&htlc_tx, 0, &htlc_redeemscript, htlc.amount_msat / 1000)[..]));
-			let our_htlc_key = secp_call!(chan_utils::derive_private_key(&self.secp_ctx, &remote_keys.per_commitment_point, &self.local_keys.htlc_base_key));
-			htlc_sigs.push(secp_call!(self.secp_ctx.sign(&htlc_sighash, &our_htlc_key)));
+			let htlc_tx = self.build_htlc_transaction(&remote_commitment_txid, htlc, false, &remote_keys);
+			let htlc_redeemscript = chan_utils::get_htlc_redeemscript(&htlc, &remote_keys);
+			let htlc_sighash = Message::from_slice(&bip143::SighashComponents::new(&htlc_tx).sighash_all(&htlc_tx.input[0], &htlc_redeemscript, htlc.amount_msat / 1000)[..]).unwrap();
+			let our_htlc_key = secp_derived_key!(chan_utils::derive_private_key(&self.secp_ctx, &remote_keys.per_commitment_point, &self.local_keys.htlc_base_key));
+			htlc_sigs.push(self.secp_ctx.sign(&htlc_sighash, &our_htlc_key).unwrap());
 		}
 
 		// Update state now that we've passed all the can-fail calls...
+		self.channel_monitor.provide_latest_remote_commitment_tx_info(&remote_commitment_tx.0, remote_commitment_tx.1, self.cur_remote_commitment_transaction_number);
 		self.channel_state |= ChannelState::AwaitingRemoteRevoke as u32;
 
-		Ok(msgs::CommitmentSigned {
+		Ok((msgs::CommitmentSigned {
 			channel_id: self.channel_id,
 			signature: our_sig,
 			htlc_signatures: htlc_sigs,
-		})
+		}, self.channel_monitor.clone()))
 	}
 
 	/// Adds a pending outbound HTLC to this channel, and creates a signed commitment transaction
 	/// to send to the remote peer in one go.
 	/// Shorthand for calling send_htlc() followed by send_commitment(), see docs on those for
 	/// more info.
-	pub fn send_htlc_and_commit(&mut self, amount_msat: u64, payment_hash: [u8; 32], cltv_expiry: u32, onion_routing_packet: msgs::OnionPacket) -> Result<Option<(msgs::UpdateAddHTLC, msgs::CommitmentSigned)>, HandleError> {
+	pub fn send_htlc_and_commit(&mut self, amount_msat: u64, payment_hash: [u8; 32], cltv_expiry: u32, onion_routing_packet: msgs::OnionPacket) -> Result<Option<(msgs::UpdateAddHTLC, msgs::CommitmentSigned, ChannelMonitor)>, HandleError> {
 		match self.send_htlc(amount_msat, payment_hash, cltv_expiry, onion_routing_packet)? {
-			Some(update_add_htlc) =>
-				Ok(Some((update_add_htlc, self.send_commitment()?))),
+			Some(update_add_htlc) => {
+				let (commitment_signed, monitor_update) = self.send_commitment_no_status_check()?;
+				Ok(Some((update_add_htlc, commitment_signed, monitor_update)))
+			},
 			None => Ok(None)
 		}
 	}
+
+	/// 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<[u8; 32]>), HandleError> {
+		for htlc in self.pending_htlcs.iter() {
+			if htlc.state == HTLCState::LocalAnnounced {
+				return Err(HandleError{err: "Cannot begin shutdown with pending HTLCs, call send_commitment first", msg: None});
+			}
+		}
+		if self.channel_state & BOTH_SIDES_SHUTDOWN_MASK != 0 {
+			return Err(HandleError{err: "Shutdown already in progress", msg: None});
+		}
+		assert_eq!(self.channel_state & ChannelState::ShutdownComplete as u32, 0);
+
+		let our_closing_script = self.get_closing_scriptpubkey();
+
+		// From here on out, we may not fail!
+		if self.channel_state < ChannelState::FundingSent as u32 {
+			self.channel_state = ChannelState::ShutdownComplete as u32;
+		} else {
+			self.channel_state |= ChannelState::LocalShutdownSent as u32;
+		}
+		self.channel_update_count += 1;
+
+		// We can't send our shutdown until we've committed all of our pending HTLCs, but the
+		// remote side is unlikely to accept any new HTLCs, so we go ahead and "free" any holding
+		// cell HTLCs and return them to fail the payment.
+		let mut dropped_outbound_htlcs = Vec::with_capacity(self.holding_cell_htlc_updates.len());
+		self.holding_cell_htlc_updates.retain(|htlc_update| {
+			match htlc_update {
+				&HTLCUpdateAwaitingACK::AddHTLC { ref payment_hash, .. } => {
+					dropped_outbound_htlcs.push(payment_hash.clone());
+					false
+				},
+				_ => true
+			}
+		});
+
+		Ok((msgs::Shutdown {
+			channel_id: self.channel_id,
+			scriptpubkey: our_closing_script,
+		}, dropped_outbound_htlcs))
+	}
+
+	/// Gets the latest commitment transaction and any dependant transactions for relay (forcing
+	/// shutdown of this channel - no more calls into this Channel may be made afterwards.
+	pub fn force_shutdown(&mut self) -> Vec<Transaction> {
+		assert!(self.channel_state != ChannelState::ShutdownComplete as u32);
+		self.channel_state = ChannelState::ShutdownComplete as u32;
+		self.channel_update_count += 1;
+		let mut res = Vec::new();
+		mem::swap(&mut res, &mut self.last_local_commitment_txn);
+		res
+	}
 }
 
 #[cfg(test)]
@@ -1688,9 +2329,10 @@ mod tests {
 	use bitcoin::util::bip143;
 	use bitcoin::network::serialize::serialize;
 	use bitcoin::blockdata::transaction::Transaction;
-	use ln::channel::{Channel,HTLCOutput,HTLCState,HTLCOutputInCommitment,TxCreationKeys};
+	use ln::channel::{Channel,ChannelKeys,HTLCOutput,HTLCState,HTLCOutputInCommitment,TxCreationKeys};
 	use ln::chan_utils;
 	use chain::chaininterface::{FeeEstimator,ConfirmationTarget};
+    use chain::transaction::OutPoint;
 	use secp256k1::{Secp256k1,Message,Signature};
 	use secp256k1::key::{SecretKey,PublicKey};
 	use crypto::sha2::Sha256;
@@ -1709,22 +2351,29 @@ mod tests {
 	fn outbound_commitment_test() {
 		// Test vectors from BOLT 3 Appendix C:
 		let feeest = TestFeeEstimator{fee_est: 15000/250};
-		let mut chan = Channel::new_outbound(&feeest, PublicKey::new(), 10000000, false, 42); // Nothing uses their network key in this test
-		chan.their_to_self_delay = 144;
-		chan.our_dust_limit_satoshis = 546;
-
 		let secp_ctx = Secp256k1::new();
 
-		chan.local_keys.funding_key = SecretKey::from_slice(&secp_ctx, &hex_bytes("30ff4956bbdd3222d44cc5e8a1261dab1e07957bdac5ae88fe3261ef321f3749").unwrap()[..]).unwrap();
-		assert_eq!(PublicKey::from_secret_key(&secp_ctx, &chan.local_keys.funding_key).unwrap().serialize()[..],
+		let chan_keys = ChannelKeys {
+			funding_key: SecretKey::from_slice(&secp_ctx, &hex_bytes("30ff4956bbdd3222d44cc5e8a1261dab1e07957bdac5ae88fe3261ef321f3749").unwrap()[..]).unwrap(),
+			payment_base_key: SecretKey::from_slice(&secp_ctx, &hex_bytes("1111111111111111111111111111111111111111111111111111111111111111").unwrap()[..]).unwrap(),
+			delayed_payment_base_key: SecretKey::from_slice(&secp_ctx, &hex_bytes("3333333333333333333333333333333333333333333333333333333333333333").unwrap()[..]).unwrap(),
+			htlc_base_key: SecretKey::from_slice(&secp_ctx, &hex_bytes("1111111111111111111111111111111111111111111111111111111111111111").unwrap()[..]).unwrap(),
+
+			// These aren't set in the test vectors:
+			revocation_base_key: SecretKey::from_slice(&secp_ctx, &hex_bytes("0fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff").unwrap()[..]).unwrap(),
+			channel_close_key: SecretKey::from_slice(&secp_ctx, &hex_bytes("0fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff").unwrap()[..]).unwrap(),
+			channel_monitor_claim_key: SecretKey::from_slice(&secp_ctx, &hex_bytes("0fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff").unwrap()[..]).unwrap(),
+			commitment_seed: [0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff],
+		};
+		assert_eq!(PublicKey::from_secret_key(&secp_ctx, &chan_keys.funding_key).unwrap().serialize()[..],
 				hex_bytes("023da092f6980e58d2c037173180e9a465476026ee50f96695963e8efe436f54eb").unwrap()[..]);
 
-		chan.local_keys.payment_base_key = SecretKey::from_slice(&secp_ctx, &hex_bytes("1111111111111111111111111111111111111111111111111111111111111111").unwrap()[..]).unwrap();
-		chan.local_keys.delayed_payment_base_key = SecretKey::from_slice(&secp_ctx, &hex_bytes("3333333333333333333333333333333333333333333333333333333333333333").unwrap()[..]).unwrap();
-		chan.local_keys.htlc_base_key = SecretKey::from_slice(&secp_ctx, &hex_bytes("1111111111111111111111111111111111111111111111111111111111111111").unwrap()[..]).unwrap();
-		// chan.local_keys.commitment_seed isn't derived in the test vectors :(
+		let mut chan = Channel::new_outbound(&feeest, chan_keys, PublicKey::new(), 10000000, false, 42); // Nothing uses their network key in this test
+		chan.their_to_self_delay = 144;
+		chan.our_dust_limit_satoshis = 546;
 
-		chan.channel_monitor.set_funding_info(Sha256dHash::from_hex("8984484a580b825b9972d7adb15050b3ab624ccd731946b3eeddb92f4e7ef6be").unwrap(), 0);
+		let funding_info = OutPoint::new(Sha256dHash::from_hex("8984484a580b825b9972d7adb15050b3ab624ccd731946b3eeddb92f4e7ef6be").unwrap(), 0);
+		chan.channel_monitor.set_funding_info(funding_info);
 
 		chan.their_payment_basepoint = PublicKey::from_secret_key(&secp_ctx, &SecretKey::from_slice(&secp_ctx, &hex_bytes("4444444444444444444444444444444444444444444444444444444444444444").unwrap()[..]).unwrap()).unwrap();
 		assert_eq!(chan.their_payment_basepoint.serialize()[..],
@@ -1753,12 +2402,12 @@ mod tests {
 
 		macro_rules! test_commitment {
 			( $their_sig_hex: expr, $our_sig_hex: expr, $tx_hex: expr) => {
-				unsigned_tx = chan.build_commitment_transaction(42, &keys, true, false).unwrap();
+				unsigned_tx = chan.build_commitment_transaction(42, &keys, true, false);
 				let their_signature = Signature::from_der(&secp_ctx, &hex_bytes($their_sig_hex).unwrap()[..]).unwrap();
-				let sighash = Message::from_slice(&bip143::SighashComponents::new(&unsigned_tx.0).sighash_all(&unsigned_tx.0, 0, &chan.get_funding_redeemscript(), chan.channel_value_satoshis)[..]).unwrap();
+				let sighash = Message::from_slice(&bip143::SighashComponents::new(&unsigned_tx.0).sighash_all(&unsigned_tx.0.input[0], &chan.get_funding_redeemscript(), chan.channel_value_satoshis)[..]).unwrap();
 				secp_ctx.verify(&sighash, &their_signature, &chan.their_funding_pubkey).unwrap();
 
-				chan.sign_commitment_transaction(&mut unsigned_tx.0, &their_signature).unwrap();
+				chan.sign_commitment_transaction(&mut unsigned_tx.0, &their_signature);
 
 				assert_eq!(serialize(&unsigned_tx.0).unwrap()[..],
 						hex_bytes($tx_hex).unwrap()[..]);
@@ -1770,9 +2419,9 @@ mod tests {
 				let remote_signature = Signature::from_der(&secp_ctx, &hex_bytes($their_sig_hex).unwrap()[..]).unwrap();
 
 				let ref htlc = unsigned_tx.1[$htlc_idx];
-				let mut htlc_tx = chan.build_htlc_transaction(&unsigned_tx.0.txid(), &htlc, true, &keys).unwrap();
-				let htlc_redeemscript = chan_utils::get_htlc_redeemscript(&htlc, &keys, htlc.offered);
-				let htlc_sighash = Message::from_slice(&bip143::SighashComponents::new(&htlc_tx).sighash_all(&htlc_tx, 0, &htlc_redeemscript, htlc.amount_msat / 1000)[..]).unwrap();
+				let mut htlc_tx = chan.build_htlc_transaction(&unsigned_tx.0.txid(), &htlc, true, &keys);
+				let htlc_redeemscript = chan_utils::get_htlc_redeemscript(&htlc, &keys);
+				let htlc_sighash = Message::from_slice(&bip143::SighashComponents::new(&htlc_tx).sighash_all(&htlc_tx.input[0], &htlc_redeemscript, htlc.amount_msat / 1000)[..]).unwrap();
 				secp_ctx.verify(&htlc_sighash, &remote_signature, &keys.b_htlc_key).unwrap();
 
 				let mut preimage: Option<[u8; 32]> = None;
@@ -1815,6 +2464,8 @@ mod tests {
 				cltv_expiry: 500,
 				payment_hash: [0; 32],
 				state: HTLCState::Committed,
+				fail_reason: None,
+				local_removed_fulfilled: false,
 				pending_forward_state: None,
 			};
 			let mut sha = Sha256::new();
@@ -1830,6 +2481,8 @@ mod tests {
 				cltv_expiry: 501,
 				payment_hash: [0; 32],
 				state: HTLCState::Committed,
+				fail_reason: None,
+				local_removed_fulfilled: false,
 				pending_forward_state: None,
 			};
 			let mut sha = Sha256::new();
@@ -1845,6 +2498,8 @@ mod tests {
 				cltv_expiry: 502,
 				payment_hash: [0; 32],
 				state: HTLCState::Committed,
+				fail_reason: None,
+				local_removed_fulfilled: false,
 				pending_forward_state: None,
 			};
 			let mut sha = Sha256::new();
@@ -1860,6 +2515,8 @@ mod tests {
 				cltv_expiry: 503,
 				payment_hash: [0; 32],
 				state: HTLCState::Committed,
+				fail_reason: None,
+				local_removed_fulfilled: false,
 				pending_forward_state: None,
 			};
 			let mut sha = Sha256::new();
@@ -1875,6 +2532,8 @@ mod tests {
 				cltv_expiry: 504,
 				payment_hash: [0; 32],
 				state: HTLCState::Committed,
+				fail_reason: None,
+				local_removed_fulfilled: false,
 				pending_forward_state: None,
 			};
 			let mut sha = Sha256::new();
@@ -2213,17 +2872,17 @@ mod tests {
 
 		seed[0..32].clone_from_slice(&hex_bytes("FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF").unwrap());
 		assert_eq!(chan_utils::build_commitment_secret(seed, 281474976710655),
-				hex_bytes("7cc854b54e3e0dcdb010d7a3fee464a9687be6e8db3be6854c475621e007a5dc").unwrap()[..]);
+		           hex_bytes("7cc854b54e3e0dcdb010d7a3fee464a9687be6e8db3be6854c475621e007a5dc").unwrap()[..]);
 
 		assert_eq!(chan_utils::build_commitment_secret(seed, 0xaaaaaaaaaaa),
-				hex_bytes("56f4008fb007ca9acf0e15b054d5c9fd12ee06cea347914ddbaed70d1c13a528").unwrap()[..]);
+		           hex_bytes("56f4008fb007ca9acf0e15b054d5c9fd12ee06cea347914ddbaed70d1c13a528").unwrap()[..]);
 
 		assert_eq!(chan_utils::build_commitment_secret(seed, 0x555555555555),
-				hex_bytes("9015daaeb06dba4ccc05b91b2f73bd54405f2be9f217fbacd3c5ac2e62327d31").unwrap()[..]);
+		           hex_bytes("9015daaeb06dba4ccc05b91b2f73bd54405f2be9f217fbacd3c5ac2e62327d31").unwrap()[..]);
 
 		seed[0..32].clone_from_slice(&hex_bytes("0101010101010101010101010101010101010101010101010101010101010101").unwrap());
 		assert_eq!(chan_utils::build_commitment_secret(seed, 1),
-				hex_bytes("915c75942a26bb3a433a8ce2cb0427c29ec6c1775cfc78328b57f6ba7bfeaa9c").unwrap()[..]);
+		           hex_bytes("915c75942a26bb3a433a8ce2cb0427c29ec6c1775cfc78328b57f6ba7bfeaa9c").unwrap()[..]);
 	}
 
 	#[test]