Refactor ChannelState to decouple state flags from states
authorWilmer Paulino <wilmer@wilmerpaulino.com>
Tue, 24 Oct 2023 23:54:20 +0000 (16:54 -0700)
committerWilmer Paulino <wilmer@wilmerpaulino.com>
Tue, 5 Dec 2023 23:05:05 +0000 (15:05 -0800)
Previously, our `ChannelState` contained bits for both states and flags.
To make matters worse, some of the flags could apply to multiple states.
This led to its API being very cumbersome, having to apply masks in most
scenarios to check for certain states. As LDK grows and more features
are added requiring more states/flags, the need for a simpler API
arises.

This refactor aims to improve this by decoupling the state flags from
the `ChannelState` enum. Each state that requires flags will now have
its own flags type, to ensure flags can only be applied to their
intended state. All of this is done while maintaining backwards and
forwards compatibility.

lightning/src/ln/channel.rs

index 9455a76140b5b627a21bb0a948caefa85dc3c1c7..ccee71fe6a0d054a6f232eaffd16de6ef6385480 100644 (file)
@@ -261,76 +261,293 @@ enum HTLCUpdateAwaitingACK {
        },
 }
 
-/// There are a few "states" and then a number of flags which can be applied:
-/// We first move through init with `OurInitSent` -> `TheirInitSent` -> `FundingCreated` -> `FundingSent`.
-/// `TheirChannelReady` and `OurChannelReady` then get set on `FundingSent`, and when both are set we
-/// move on to `ChannelReady`.
-/// Note that `PeerDisconnected` can be set on both `ChannelReady` and `FundingSent`.
-/// `ChannelReady` can then get all remaining flags set on it, until we finish shutdown, then we
-/// move on to `ShutdownComplete`, at which point most calls into this channel are disallowed.
+macro_rules! define_state_flags {
+       ($flag_type_doc: expr, $flag_type: ident, [$(($flag_doc: expr, $flag: ident, $value: expr)),+], $extra_flags: expr) => {
+               #[doc = $flag_type_doc]
+               #[derive(Copy, Clone, Debug, PartialEq, PartialOrd, Eq)]
+               struct $flag_type(u32);
+
+               impl $flag_type {
+                       $(
+                               #[doc = $flag_doc]
+                               const $flag: $flag_type = $flag_type($value);
+                       )*
+
+                       /// All flags that apply to the specified [`ChannelState`] variant.
+                       #[allow(unused)]
+                       const ALL: $flag_type = Self($(Self::$flag.0 | )* $extra_flags);
+
+                       #[allow(unused)]
+                       fn new() -> Self { Self(0) }
+
+                       #[allow(unused)]
+                       fn from_u32(flags: u32) -> Result<Self, ()> {
+                               if flags & !Self::ALL.0 != 0 {
+                                       Err(())
+                               } else {
+                                       Ok($flag_type(flags))
+                               }
+                       }
+
+                       #[allow(unused)]
+                       fn is_empty(&self) -> bool { self.0 == 0 }
+
+                       #[allow(unused)]
+                       fn is_set(&self, flag: Self) -> bool { *self & flag == flag }
+               }
+
+               impl core::ops::Not for $flag_type {
+                       type Output = Self;
+                       fn not(self) -> Self::Output { Self(!self.0) }
+               }
+               impl core::ops::BitOr for $flag_type {
+                       type Output = Self;
+                       fn bitor(self, rhs: Self) -> Self::Output { Self(self.0 | rhs.0) }
+               }
+               impl core::ops::BitOrAssign for $flag_type {
+                       fn bitor_assign(&mut self, rhs: Self) { self.0 |= rhs.0; }
+               }
+               impl core::ops::BitAnd for $flag_type {
+                       type Output = Self;
+                       fn bitand(self, rhs: Self) -> Self::Output { Self(self.0 & rhs.0) }
+               }
+               impl core::ops::BitAndAssign for $flag_type {
+                       fn bitand_assign(&mut self, rhs: Self) { self.0 &= rhs.0; }
+               }
+       };
+       ($flag_type_doc: expr, $flag_type: ident, $flags: tt) => {
+               define_state_flags!($flag_type_doc, $flag_type, $flags, 0);
+       };
+       ($flag_type_doc: expr, FUNDED_STATE, $flag_type: ident, $flags: tt) => {
+               define_state_flags!($flag_type_doc, $flag_type, $flags, FundedStateFlags::ALL.0);
+               impl core::ops::BitOr<FundedStateFlags> for $flag_type {
+                       type Output = Self;
+                       fn bitor(self, rhs: FundedStateFlags) -> Self::Output { Self(self.0 | rhs.0) }
+               }
+               impl core::ops::BitOrAssign<FundedStateFlags> for $flag_type {
+                       fn bitor_assign(&mut self, rhs: FundedStateFlags) { self.0 |= rhs.0; }
+               }
+               impl core::ops::BitAnd<FundedStateFlags> for $flag_type {
+                       type Output = Self;
+                       fn bitand(self, rhs: FundedStateFlags) -> Self::Output { Self(self.0 & rhs.0) }
+               }
+               impl core::ops::BitAndAssign<FundedStateFlags> for $flag_type {
+                       fn bitand_assign(&mut self, rhs: FundedStateFlags) { self.0 &= rhs.0; }
+               }
+               impl PartialEq<FundedStateFlags> for $flag_type {
+                       fn eq(&self, other: &FundedStateFlags) -> bool { self.0 == other.0 }
+               }
+               impl From<FundedStateFlags> for $flag_type {
+                       fn from(flags: FundedStateFlags) -> Self { Self(flags.0) }
+               }
+       };
+}
+
+/// We declare all the states/flags here together to help determine which bits are still available
+/// to choose.
+mod state_flags {
+       pub const OUR_INIT_SENT: u32 = 1 << 0;
+       pub const THEIR_INIT_SENT: u32 = 1 << 1;
+       pub const FUNDING_CREATED: u32 = 1 << 2;
+       pub const FUNDING_SENT: u32 = 1 << 3;
+       pub const THEIR_CHANNEL_READY: u32 = 1 << 4;
+       pub const OUR_CHANNEL_READY: u32 = 1 << 5;
+       pub const CHANNEL_READY: u32 = 1 << 6;
+       pub const PEER_DISCONNECTED: u32 = 1 << 7;
+       pub const MONITOR_UPDATE_IN_PROGRESS: u32 = 1 << 8;
+       pub const AWAITING_REMOTE_REVOKE: u32 = 1 << 9;
+       pub const REMOTE_SHUTDOWN_SENT: u32 = 1 << 10;
+       pub const LOCAL_SHUTDOWN_SENT: u32 = 1 << 11;
+       pub const SHUTDOWN_COMPLETE: u32 = 1 << 12;
+       pub const WAITING_FOR_BATCH: u32 = 1 << 13;
+}
+
+define_state_flags!(
+       "Flags that apply to all [`ChannelState`] variants in which the channel is funded.",
+       FundedStateFlags, [
+               ("Indicates the remote side is considered \"disconnected\" and no updates are allowed \
+                       until after we've done a `channel_reestablish` dance.", PEER_DISCONNECTED, state_flags::PEER_DISCONNECTED),
+               ("Indicates the user has told us a `ChannelMonitor` update is pending async persistence \
+                       somewhere and we should pause sending any outbound messages until they've managed to \
+                       complete it.", MONITOR_UPDATE_IN_PROGRESS, state_flags::MONITOR_UPDATE_IN_PROGRESS),
+               ("Indicates we received 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.", REMOTE_SHUTDOWN_SENT, state_flags::REMOTE_SHUTDOWN_SENT),
+               ("Indicates we sent a `shutdown` message. At this point, we may not add any new HTLCs to \
+                       the channel.", LOCAL_SHUTDOWN_SENT, state_flags::LOCAL_SHUTDOWN_SENT)
+       ]
+);
+
+define_state_flags!(
+       "Flags that only apply to [`ChannelState::NegotiatingFunding`].",
+       NegotiatingFundingFlags, [
+               ("Indicates we have (or are prepared to) send our `open_channel`/`accept_channel` message.",
+                       OUR_INIT_SENT, state_flags::OUR_INIT_SENT),
+               ("Indicates we have received their `open_channel`/`accept_channel` message.",
+                       THEIR_INIT_SENT, state_flags::THEIR_INIT_SENT)
+       ]
+);
+
+define_state_flags!(
+       "Flags that only apply to [`ChannelState::FundingSent`].",
+       FUNDED_STATE, FundingSentFlags, [
+               ("Indicates they sent us a `channel_ready` message. Once both `THEIR_CHANNEL_READY` and \
+                       `OUR_CHANNEL_READY` are set, our state moves on to `ChannelReady`.",
+                       THEIR_CHANNEL_READY, state_flags::THEIR_CHANNEL_READY),
+               ("Indicates we sent them a `channel_ready` message. Once both `THEIR_CHANNEL_READY` and \
+                       `OUR_CHANNEL_READY` are set, our state moves on to `ChannelReady`.",
+                       OUR_CHANNEL_READY, state_flags::OUR_CHANNEL_READY),
+               ("Indicates the channel was funded in a batch and the broadcast of the funding transaction \
+                       is being held until all channels in the batch have received `funding_signed` and have \
+                       their monitors persisted.", WAITING_FOR_BATCH, state_flags::WAITING_FOR_BATCH)
+       ]
+);
+
+define_state_flags!(
+       "Flags that only apply to [`ChannelState::ChannelReady`].",
+       FUNDED_STATE, ChannelReadyFlags, [
+               ("Indicates that we have sent a `commitment_signed` but are awaiting the responding \
+                       `revoke_and_ack` message. During this period, we can't generate new `commitment_signed` \
+                       messages as we'd be unable to determine which HTLCs they included in their `revoke_and_ack` \
+                       implicit ACK, so instead we have to hold them away temporarily to be sent later.",
+                       AWAITING_REMOTE_REVOKE, state_flags::AWAITING_REMOTE_REVOKE)
+       ]
+);
+
+#[derive(Copy, Clone, Debug, PartialEq, PartialOrd, Eq)]
 enum ChannelState {
-       /// Implies we have (or are prepared to) send our open_channel/accept_channel message
-       OurInitSent = 1 << 0,
-       /// Implies we have received their `open_channel`/`accept_channel` message
-       TheirInitSent = 1 << 1,
-       /// We have sent `funding_created` and are awaiting a `funding_signed` to advance to `FundingSent`.
-       /// Note that this is nonsense for an inbound channel as we immediately generate `funding_signed`
-       /// upon receipt of `funding_created`, so simply skip this state.
-       FundingCreated = 4,
-       /// Set when we have received/sent `funding_created` and `funding_signed` and are thus now waiting
-       /// on the funding transaction to confirm. The `ChannelReady` flags are set to indicate when we
-       /// and our counterparty consider the funding transaction confirmed.
-       FundingSent = 8,
-       /// Flag which can be set on `FundingSent` to indicate they sent us a `channel_ready` message.
-       /// Once both `TheirChannelReady` and `OurChannelReady` are set, state moves on to `ChannelReady`.
-       TheirChannelReady = 1 << 4,
-       /// Flag which can be set on `FundingSent` to indicate we sent them a `channel_ready` message.
-       /// Once both `TheirChannelReady` and `OurChannelReady` are set, state moves on to `ChannelReady`.
-       OurChannelReady = 1 << 5,
-       ChannelReady = 64,
-       /// Flag which is set on `ChannelReady` and `FundingSent` indicating remote side is considered
-       /// "disconnected" and no updates are allowed until after we've done a `channel_reestablish`
-       /// dance.
-       PeerDisconnected = 1 << 7,
-       /// Flag which is set on `ChannelReady`, FundingCreated, and `FundingSent` indicating the user has
-       /// told us a `ChannelMonitor` update is pending async persistence somewhere and we should pause
-       /// sending any outbound messages until they've managed to finish.
-       MonitorUpdateInProgress = 1 << 8,
-       /// Flag which implies that we have sent a commitment_signed but are awaiting the responding
-       /// revoke_and_ack message. During this time period, we can't generate new commitment_signed
-       /// messages as then we will be unable to determine which HTLCs they included in their
-       /// revoke_and_ack implicit ACK, so instead we have to hold them away temporarily to be sent
-       /// later.
-       /// Flag is set on `ChannelReady`.
-       AwaitingRemoteRevoke = 1 << 9,
-       /// Flag which is set on `ChannelReady` 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 << 10,
-       /// Flag which is set on `ChannelReady` or `FundingSent` after sending a shutdown message. At this
-       /// point, we may not add any new HTLCs to the channel.
-       LocalShutdownSent = 1 << 11,
-       /// We've successfully negotiated a closing_signed dance. At this point ChannelManager is about
-       /// to drop us, but we store this anyway.
-       ShutdownComplete = 4096,
-       /// Flag which is set on `FundingSent` to indicate this channel is funded in a batch and the
-       /// broadcasting of the funding transaction is being held until all channels in the batch
-       /// have received funding_signed and have their monitors persisted.
-       WaitingForBatch = 1 << 13,
+       /// We are negotiating the parameters required for the channel prior to funding it.
+       NegotiatingFunding(NegotiatingFundingFlags),
+       /// We have sent `funding_created` and are awaiting a `funding_signed` to advance to
+       /// `FundingSent`. Note that this is nonsense for an inbound channel as we immediately generate
+       /// `funding_signed` upon receipt of `funding_created`, so simply skip this state.
+       FundingCreated,
+       /// We've received/sent `funding_created` and `funding_signed` and are thus now waiting on the
+       /// funding transaction to confirm.
+       FundingSent(FundingSentFlags),
+       /// Both we and our counterparty consider the funding transaction confirmed and the channel is
+       /// now operational.
+       ChannelReady(ChannelReadyFlags),
+       /// We've successfully negotiated a `closing_signed` dance. At this point, the `ChannelManager`
+       /// is about to drop us, but we store this anyway.
+       ShutdownComplete,
+}
+
+macro_rules! impl_state_flag {
+       ($get: ident, $set: ident, $clear: ident, $state_flag: expr, [$($state: ident),+]) => {
+               #[allow(unused)]
+               fn $get(&self) -> bool {
+                       match self {
+                               $(
+                                       ChannelState::$state(flags) => flags.is_set($state_flag.into()),
+                               )*
+                               _ => false,
+                       }
+               }
+               #[allow(unused)]
+               fn $set(&mut self) {
+                       match self {
+                               $(
+                                       ChannelState::$state(flags) => *flags |= $state_flag,
+                               )*
+                               _ => debug_assert!(false, "Attempted to set flag on unexpected ChannelState"),
+                       }
+               }
+               #[allow(unused)]
+               fn $clear(&mut self) {
+                       match self {
+                               $(
+                                       ChannelState::$state(flags) => *flags &= !($state_flag),
+                               )*
+                               _ => debug_assert!(false, "Attempted to clear flag on unexpected ChannelState"),
+                       }
+               }
+       };
+       ($get: ident, $set: ident, $clear: ident, $state_flag: expr, FUNDED_STATES) => {
+               impl_state_flag!($get, $set, $clear, $state_flag, [FundingSent, ChannelReady]);
+       };
+       ($get: ident, $set: ident, $clear: ident, $state_flag: expr, $state: ident) => {
+               impl_state_flag!($get, $set, $clear, $state_flag, [$state]);
+       };
+}
+
+impl ChannelState {
+       fn from_u32(state: u32) -> Result<Self, ()> {
+               match state {
+                       state_flags::FUNDING_CREATED => Ok(ChannelState::FundingCreated),
+                       state_flags::SHUTDOWN_COMPLETE => Ok(ChannelState::ShutdownComplete),
+                       val => {
+                               if val & state_flags::FUNDING_SENT == state_flags::FUNDING_SENT {
+                                       FundingSentFlags::from_u32(val & !state_flags::FUNDING_SENT)
+                                               .map(|flags| ChannelState::FundingSent(flags))
+                               } else if val & state_flags::CHANNEL_READY == state_flags::CHANNEL_READY {
+                                       ChannelReadyFlags::from_u32(val & !state_flags::CHANNEL_READY)
+                                               .map(|flags| ChannelState::ChannelReady(flags))
+                               } else if let Ok(flags) = NegotiatingFundingFlags::from_u32(val) {
+                                       Ok(ChannelState::NegotiatingFunding(flags))
+                               } else {
+                                       Err(())
+                               }
+                       },
+               }
+       }
+
+       fn to_u32(&self) -> u32 {
+               match self {
+                       ChannelState::NegotiatingFunding(flags) => flags.0,
+                       ChannelState::FundingCreated => state_flags::FUNDING_CREATED,
+                       ChannelState::FundingSent(flags) => state_flags::FUNDING_SENT | flags.0,
+                       ChannelState::ChannelReady(flags) => state_flags::CHANNEL_READY | flags.0,
+                       ChannelState::ShutdownComplete => state_flags::SHUTDOWN_COMPLETE,
+               }
+       }
+
+       fn is_pre_funded_state(&self) -> bool {
+               matches!(self, ChannelState::NegotiatingFunding(_)|ChannelState::FundingCreated)
+       }
+
+       fn is_both_sides_shutdown(&self) -> bool {
+               self.is_local_shutdown_sent() && self.is_remote_shutdown_sent()
+       }
+
+       fn with_funded_state_flags_mask(&self) -> FundedStateFlags {
+               match self {
+                       ChannelState::FundingSent(flags) => FundedStateFlags((*flags & FundedStateFlags::ALL).0),
+                       ChannelState::ChannelReady(flags) => FundedStateFlags((*flags & FundedStateFlags::ALL).0),
+                       _ => FundedStateFlags::new(),
+               }
+       }
+
+       fn should_force_holding_cell(&self) -> bool {
+               match self {
+                       ChannelState::ChannelReady(flags) =>
+                               flags.is_set(ChannelReadyFlags::AWAITING_REMOTE_REVOKE) ||
+                                       flags.is_set(FundedStateFlags::MONITOR_UPDATE_IN_PROGRESS.into()) ||
+                                       flags.is_set(FundedStateFlags::PEER_DISCONNECTED.into()),
+                       _ => {
+                               debug_assert!(false, "The holding cell is only valid within ChannelReady");
+                               false
+                       },
+               }
+       }
+
+       impl_state_flag!(is_peer_disconnected, set_peer_disconnected, clear_peer_disconnected,
+               FundedStateFlags::PEER_DISCONNECTED, FUNDED_STATES);
+       impl_state_flag!(is_monitor_update_in_progress, set_monitor_update_in_progress, clear_monitor_update_in_progress,
+               FundedStateFlags::MONITOR_UPDATE_IN_PROGRESS, FUNDED_STATES);
+       impl_state_flag!(is_local_shutdown_sent, set_local_shutdown_sent, clear_local_shutdown_sent,
+               FundedStateFlags::LOCAL_SHUTDOWN_SENT, FUNDED_STATES);
+       impl_state_flag!(is_remote_shutdown_sent, set_remote_shutdown_sent, clear_remote_shutdown_sent,
+               FundedStateFlags::REMOTE_SHUTDOWN_SENT, FUNDED_STATES);
+       impl_state_flag!(is_our_channel_ready, set_our_channel_ready, clear_our_channel_ready,
+               FundingSentFlags::OUR_CHANNEL_READY, FundingSent);
+       impl_state_flag!(is_their_channel_ready, set_their_channel_ready, clear_their_channel_ready,
+               FundingSentFlags::THEIR_CHANNEL_READY, FundingSent);
+       impl_state_flag!(is_waiting_for_batch, set_waiting_for_batch, clear_waiting_for_batch,
+               FundingSentFlags::WAITING_FOR_BATCH, FundingSent);
+       impl_state_flag!(is_awaiting_remote_revoke, set_awaiting_remote_revoke, clear_awaiting_remote_revoke,
+               ChannelReadyFlags::AWAITING_REMOTE_REVOKE, ChannelReady);
 }
-const BOTH_SIDES_SHUTDOWN_MASK: u32 =
-       ChannelState::LocalShutdownSent as u32 |
-       ChannelState::RemoteShutdownSent as u32;
-const MULTI_STATE_FLAGS: u32 =
-       BOTH_SIDES_SHUTDOWN_MASK |
-       ChannelState::PeerDisconnected as u32 |
-       ChannelState::MonitorUpdateInProgress as u32;
-const STATE_FLAGS: u32 =
-       MULTI_STATE_FLAGS |
-       ChannelState::TheirChannelReady as u32 |
-       ChannelState::OurChannelReady as u32 |
-       ChannelState::AwaitingRemoteRevoke as u32 |
-       ChannelState::WaitingForBatch as u32;
 
 pub const INITIAL_COMMITMENT_NUMBER: u64 = (1 << 48) - 1;
 
@@ -743,7 +960,7 @@ pub(super) struct ChannelContext<SP: Deref> where SP::Target: SignerProvider {
        /// The temporary channel ID used during channel setup. Value kept even after transitioning to a final channel ID.
        /// Will be `None` for channels created prior to 0.0.115.
        temporary_channel_id: Option<ChannelId>,
-       channel_state: u32,
+       channel_state: ChannelState,
 
        // When we reach max(6 blocks, minimum_depth), we need to send an AnnouncementSigs message to
        // our peer. However, we want to make sure they received it, or else rebroadcast it when we
@@ -1040,49 +1257,55 @@ impl<SP: Deref> ChannelContext<SP> where SP::Target: SignerProvider  {
 
        /// Returns true if we've ever received a message from the remote end for this Channel
        pub fn have_received_message(&self) -> bool {
-               self.channel_state & !STATE_FLAGS > (ChannelState::OurInitSent as u32)
+               self.channel_state > ChannelState::NegotiatingFunding(NegotiatingFundingFlags::OUR_INIT_SENT)
        }
 
        /// Returns true if this channel is fully established and not known to be closing.
        /// Allowed in any state (including after shutdown)
        pub fn is_usable(&self) -> bool {
-               let mask = ChannelState::ChannelReady as u32 | BOTH_SIDES_SHUTDOWN_MASK;
-               (self.channel_state & mask) == (ChannelState::ChannelReady as u32) && !self.monitor_pending_channel_ready
+               matches!(self.channel_state, ChannelState::ChannelReady(_)) &&
+                       !self.channel_state.is_local_shutdown_sent() &&
+                       !self.channel_state.is_remote_shutdown_sent() &&
+                       !self.monitor_pending_channel_ready
        }
 
        /// shutdown state returns the state of the channel in its various stages of shutdown
        pub fn shutdown_state(&self) -> ChannelShutdownState {
-               if self.channel_state & (ChannelState::ShutdownComplete as u32) != 0 {
-                       return ChannelShutdownState::ShutdownComplete;
-               }
-               if self.channel_state & (ChannelState::LocalShutdownSent as u32) != 0 &&  self.channel_state & (ChannelState::RemoteShutdownSent as u32) == 0 {
-                       return ChannelShutdownState::ShutdownInitiated;
-               }
-               if (self.channel_state & BOTH_SIDES_SHUTDOWN_MASK != 0) && !self.closing_negotiation_ready() {
-                       return ChannelShutdownState::ResolvingHTLCs;
-               }
-               if (self.channel_state & BOTH_SIDES_SHUTDOWN_MASK != 0) && self.closing_negotiation_ready() {
-                       return ChannelShutdownState::NegotiatingClosingFee;
+               match self.channel_state {
+                       ChannelState::FundingSent(_)|ChannelState::ChannelReady(_) =>
+                               if self.channel_state.is_local_shutdown_sent() && !self.channel_state.is_remote_shutdown_sent() {
+                                       ChannelShutdownState::ShutdownInitiated
+                               } else if (self.channel_state.is_local_shutdown_sent() || self.channel_state.is_remote_shutdown_sent()) && !self.closing_negotiation_ready() {
+                                       ChannelShutdownState::ResolvingHTLCs
+                               } else if (self.channel_state.is_local_shutdown_sent() || self.channel_state.is_remote_shutdown_sent()) && self.closing_negotiation_ready() {
+                                       ChannelShutdownState::NegotiatingClosingFee
+                               } else {
+                                       ChannelShutdownState::NotShuttingDown
+                               },
+                       ChannelState::ShutdownComplete => ChannelShutdownState::ShutdownComplete,
+                       _ => ChannelShutdownState::NotShuttingDown,
                }
-               return ChannelShutdownState::NotShuttingDown;
        }
 
        fn closing_negotiation_ready(&self) -> bool {
+               let is_ready_to_close = match self.channel_state {
+                       ChannelState::FundingSent(flags) =>
+                               flags & FundedStateFlags::ALL == FundedStateFlags::LOCAL_SHUTDOWN_SENT | FundedStateFlags::REMOTE_SHUTDOWN_SENT,
+                       ChannelState::ChannelReady(flags) =>
+                               flags == FundedStateFlags::LOCAL_SHUTDOWN_SENT | FundedStateFlags::REMOTE_SHUTDOWN_SENT,
+                       _ => false,
+               };
                self.pending_inbound_htlcs.is_empty() &&
-               self.pending_outbound_htlcs.is_empty() &&
-               self.pending_update_fee.is_none() &&
-               self.channel_state &
-               (BOTH_SIDES_SHUTDOWN_MASK |
-                       ChannelState::AwaitingRemoteRevoke as u32 |
-                       ChannelState::PeerDisconnected as u32 |
-                       ChannelState::MonitorUpdateInProgress as u32) == BOTH_SIDES_SHUTDOWN_MASK
+                       self.pending_outbound_htlcs.is_empty() &&
+                       self.pending_update_fee.is_none() &&
+                       is_ready_to_close
        }
 
        /// Returns true if this channel is currently available for use. This is a superset of
        /// is_usable() and considers things like the channel being temporarily disabled.
        /// Allowed in any state (including after shutdown)
        pub fn is_live(&self) -> bool {
-               self.is_usable() && (self.channel_state & (ChannelState::PeerDisconnected as u32) == 0)
+               self.is_usable() && !self.channel_state.is_peer_disconnected()
        }
 
        // Public utilities:
@@ -1334,8 +1557,8 @@ impl<SP: Deref> ChannelContext<SP> where SP::Target: SignerProvider  {
        /// Returns true if funding_signed was sent/received and the
        /// funding transaction has been broadcast if necessary.
        pub fn is_funding_broadcast(&self) -> bool {
-               self.channel_state & !STATE_FLAGS >= ChannelState::FundingSent as u32 &&
-                       self.channel_state & ChannelState::WaitingForBatch as u32 == 0
+               !self.channel_state.is_pre_funded_state() &&
+                       !matches!(self.channel_state, ChannelState::FundingSent(flags) if flags.is_set(FundingSentFlags::WAITING_FOR_BATCH))
        }
 
        /// Transaction nomenclature is somewhat confusing here as there are many different cases - a
@@ -2091,11 +2314,14 @@ impl<SP: Deref> ChannelContext<SP> where SP::Target: SignerProvider  {
 
        fn if_unbroadcasted_funding<F, O>(&self, f: F) -> Option<O>
                where F: Fn() -> Option<O> {
-               if self.channel_state & ChannelState::FundingCreated as u32 != 0 ||
-                  self.channel_state & ChannelState::WaitingForBatch as u32 != 0 {
-                       f()
-               } else {
-                       None
+               match self.channel_state {
+                       ChannelState::FundingCreated => f(),
+                       ChannelState::FundingSent(flags) => if flags.is_set(FundingSentFlags::WAITING_FOR_BATCH) {
+                               f()
+                       } else {
+                               None
+                       },
+                       _ => None,
                }
        }
 
@@ -2134,7 +2360,7 @@ impl<SP: Deref> ChannelContext<SP> where SP::Target: SignerProvider  {
                // called during initialization prior to the chain_monitor in the encompassing ChannelManager
                // being fully configured in some cases. Thus, its likely any monitor events we generate will
                // be delayed in being processed! See the docs for `ChannelManagerReadArgs` for more.
-               assert!(self.channel_state != ChannelState::ShutdownComplete as u32);
+               assert!(!matches!(self.channel_state, ChannelState::ShutdownComplete));
 
                // We go ahead and "free" any holding cell HTLCs or HTLCs we haven't yet committed to and
                // return them to fail the payment.
@@ -2156,7 +2382,11 @@ impl<SP: Deref> ChannelContext<SP> where SP::Target: SignerProvider  {
                        // funding transaction, don't return a funding txo (which prevents providing the
                        // monitor update to the user, even if we return one).
                        // See test_duplicate_chan_id and test_pre_lockin_no_chan_closed_update for more.
-                       if self.channel_state & (ChannelState::FundingSent as u32 | ChannelState::ChannelReady as u32 | ChannelState::ShutdownComplete as u32) != 0 {
+                       let generate_monitor_update = match self.channel_state {
+                               ChannelState::FundingSent(_)|ChannelState::ChannelReady(_)|ChannelState::ShutdownComplete => true,
+                               _ => false,
+                       };
+                       if generate_monitor_update {
                                self.latest_monitor_update_id = CLOSED_CHANNEL_UPDATE_ID;
                                Some((self.get_counterparty_node_id(), funding_txo, ChannelMonitorUpdate {
                                        update_id: self.latest_monitor_update_id,
@@ -2166,7 +2396,7 @@ impl<SP: Deref> ChannelContext<SP> where SP::Target: SignerProvider  {
                } else { None };
                let unbroadcasted_batch_funding_txid = self.unbroadcasted_batch_funding_txid();
 
-               self.channel_state = ChannelState::ShutdownComplete as u32;
+               self.channel_state = ChannelState::ShutdownComplete;
                self.update_time_counter += 1;
                ShutdownResult {
                        monitor_update,
@@ -2437,7 +2667,7 @@ impl<SP: Deref> Channel<SP> where
        where L::Target: Logger {
                // Assert that we'll add the HTLC claim to the holding cell in `get_update_fulfill_htlc`
                // (see equivalent if condition there).
-               assert!(self.context.channel_state & (ChannelState::AwaitingRemoteRevoke as u32 | ChannelState::PeerDisconnected as u32 | ChannelState::MonitorUpdateInProgress as u32) != 0);
+               assert!(self.context.channel_state.should_force_holding_cell());
                let mon_update_id = self.context.latest_monitor_update_id; // Forget the ChannelMonitor update
                let fulfill_resp = self.get_update_fulfill_htlc(htlc_id_arg, payment_preimage_arg, logger);
                self.context.latest_monitor_update_id = mon_update_id;
@@ -2451,10 +2681,9 @@ impl<SP: Deref> Channel<SP> where
                // 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.context.channel_state & (ChannelState::ChannelReady as u32)) != (ChannelState::ChannelReady as u32) {
+               if !matches!(self.context.channel_state, ChannelState::ChannelReady(_)) {
                        panic!("Was asked to fulfill an HTLC when channel was not in an operational state");
                }
-               assert_eq!(self.context.channel_state & ChannelState::ShutdownComplete as u32, 0);
 
                // ChannelManager may generate duplicate claims/fails due to HTLC update events from
                // on-chain ChannelsMonitors during block rescan. Ideally we'd figure out a way to drop
@@ -2507,7 +2736,7 @@ impl<SP: Deref> Channel<SP> where
                        }],
                };
 
-               if (self.context.channel_state & (ChannelState::AwaitingRemoteRevoke as u32 | ChannelState::PeerDisconnected as u32 | ChannelState::MonitorUpdateInProgress as u32)) != 0 {
+               if self.context.channel_state.should_force_holding_cell() {
                        // Note that this condition is the same as the assertion in
                        // `claim_htlc_while_disconnected_dropping_mon_update` and must match exactly -
                        // `claim_htlc_while_disconnected_dropping_mon_update` would not work correctly if we
@@ -2535,7 +2764,7 @@ impl<SP: Deref> Channel<SP> where
                                        _ => {}
                                }
                        }
-                       log_trace!(logger, "Adding HTLC claim to holding_cell in channel {}! Current state: {}", &self.context.channel_id(), self.context.channel_state);
+                       log_trace!(logger, "Adding HTLC claim to holding_cell in channel {}! Current state: {}", &self.context.channel_id(), self.context.channel_state.to_u32());
                        self.context.holding_cell_htlc_updates.push(HTLCUpdateAwaitingACK::ClaimHTLC {
                                payment_preimage: payment_preimage_arg, htlc_id: htlc_id_arg,
                        });
@@ -2630,10 +2859,9 @@ impl<SP: Deref> Channel<SP> where
        /// [`ChannelError::Ignore`].
        fn fail_htlc<L: Deref>(&mut self, htlc_id_arg: u64, err_packet: msgs::OnionErrorPacket, mut force_holding_cell: bool, logger: &L)
        -> Result<Option<msgs::UpdateFailHTLC>, ChannelError> where L::Target: Logger {
-               if (self.context.channel_state & (ChannelState::ChannelReady as u32)) != (ChannelState::ChannelReady as u32) {
+               if !matches!(self.context.channel_state, ChannelState::ChannelReady(_)) {
                        panic!("Was asked to fail an HTLC when channel was not in an operational state");
                }
-               assert_eq!(self.context.channel_state & ChannelState::ShutdownComplete as u32, 0);
 
                // ChannelManager may generate duplicate claims/fails due to HTLC update events from
                // on-chain ChannelsMonitors during block rescan. Ideally we'd figure out a way to drop
@@ -2667,7 +2895,7 @@ impl<SP: Deref> Channel<SP> where
                        return Ok(None);
                }
 
-               if (self.context.channel_state & (ChannelState::AwaitingRemoteRevoke as u32 | ChannelState::PeerDisconnected as u32 | ChannelState::MonitorUpdateInProgress as u32)) != 0 {
+               if self.context.channel_state.should_force_holding_cell() {
                        debug_assert!(force_holding_cell, "!force_holding_cell is only called when emptying the holding cell, so we shouldn't end up back in it!");
                        force_holding_cell = true;
                }
@@ -2726,7 +2954,7 @@ impl<SP: Deref> Channel<SP> where
                if !self.context.is_outbound() {
                        return Err(ChannelError::Close("Received funding_signed for an inbound channel?".to_owned()));
                }
-               if self.context.channel_state & !(ChannelState::MonitorUpdateInProgress as u32) != ChannelState::FundingCreated as u32 {
+               if !matches!(self.context.channel_state, ChannelState::FundingCreated) {
                        return Err(ChannelError::Close("Received funding_signed in strange state!".to_owned()));
                }
                if self.context.commitment_secrets.get_min_seen_secret() != (1 << 48) ||
@@ -2792,11 +3020,11 @@ impl<SP: Deref> Channel<SP> where
                        counterparty_initial_commitment_tx.to_broadcaster_value_sat(),
                        counterparty_initial_commitment_tx.to_countersignatory_value_sat(), &&logger_with_chan_monitor);
 
-               assert_eq!(self.context.channel_state & (ChannelState::MonitorUpdateInProgress as u32), 0); // We have no had any monitor(s) yet to fail update!
+               assert!(!self.context.channel_state.is_monitor_update_in_progress()); // We have no had any monitor(s) yet to fail update!
                if self.context.is_batch_funding() {
-                       self.context.channel_state = ChannelState::FundingSent as u32 | ChannelState::WaitingForBatch as u32;
+                       self.context.channel_state = ChannelState::FundingSent(FundingSentFlags::WAITING_FOR_BATCH);
                } else {
-                       self.context.channel_state = ChannelState::FundingSent as u32;
+                       self.context.channel_state = ChannelState::FundingSent(FundingSentFlags::new());
                }
                self.context.cur_holder_commitment_transaction_number -= 1;
                self.context.cur_counterparty_commitment_transaction_number -= 1;
@@ -2814,7 +3042,7 @@ impl<SP: Deref> Channel<SP> where
        /// treated as a non-batch channel going forward.
        pub fn set_batch_ready(&mut self) {
                self.context.is_batch_funding = None;
-               self.context.channel_state &= !(ChannelState::WaitingForBatch as u32);
+               self.context.channel_state.clear_waiting_for_batch();
        }
 
        /// Handles a channel_ready message from our peer. If we've already sent our channel_ready
@@ -2828,7 +3056,7 @@ impl<SP: Deref> Channel<SP> where
                NS::Target: NodeSigner,
                L::Target: Logger
        {
-               if self.context.channel_state & (ChannelState::PeerDisconnected as u32) == ChannelState::PeerDisconnected as u32 {
+               if self.context.channel_state.is_peer_disconnected() {
                        self.context.workaround_lnd_bug_4006 = Some(msg.clone());
                        return Err(ChannelError::Ignore("Peer sent channel_ready when we needed a channel_reestablish. The peer is likely lnd, see https://github.com/lightningnetwork/lnd/issues/4006".to_owned()));
                }
@@ -2842,24 +3070,31 @@ impl<SP: Deref> Channel<SP> where
                        }
                }
 
-               let non_shutdown_state = self.context.channel_state & (!MULTI_STATE_FLAGS);
-
                // Our channel_ready shouldn't have been sent if we are waiting for other channels in the
                // batch, but we can receive channel_ready messages.
-               debug_assert!(
-                       non_shutdown_state & ChannelState::OurChannelReady as u32 == 0 ||
-                       non_shutdown_state & ChannelState::WaitingForBatch as u32 == 0
-               );
-               if non_shutdown_state & !(ChannelState::WaitingForBatch as u32) == ChannelState::FundingSent as u32 {
-                       self.context.channel_state |= ChannelState::TheirChannelReady as u32;
-               } else if non_shutdown_state == (ChannelState::FundingSent as u32 | ChannelState::OurChannelReady as u32) {
-                       self.context.channel_state = ChannelState::ChannelReady as u32 | (self.context.channel_state & MULTI_STATE_FLAGS);
-                       self.context.update_time_counter += 1;
-               } else if self.context.channel_state & (ChannelState::ChannelReady as u32) != 0 ||
-                       // If we reconnected before sending our `channel_ready` they may still resend theirs:
-                       (self.context.channel_state & (ChannelState::FundingSent as u32 | ChannelState::TheirChannelReady as u32) ==
-                                             (ChannelState::FundingSent as u32 | ChannelState::TheirChannelReady as u32))
-               {
+               let mut check_reconnection = false;
+               match &self.context.channel_state {
+                       ChannelState::FundingSent(flags) => {
+                               let flags = *flags & !FundedStateFlags::ALL;
+                               debug_assert!(!flags.is_set(FundingSentFlags::OUR_CHANNEL_READY) || !flags.is_set(FundingSentFlags::WAITING_FOR_BATCH));
+                               if flags & !FundingSentFlags::WAITING_FOR_BATCH == FundingSentFlags::THEIR_CHANNEL_READY {
+                                       // If we reconnected before sending our `channel_ready` they may still resend theirs.
+                                       check_reconnection = true;
+                               } else if (flags & !FundingSentFlags::WAITING_FOR_BATCH).is_empty() {
+                                       self.context.channel_state.set_their_channel_ready();
+                               } else if flags == FundingSentFlags::OUR_CHANNEL_READY {
+                                       self.context.channel_state = ChannelState::ChannelReady(self.context.channel_state.with_funded_state_flags_mask().into());
+                                       self.context.update_time_counter += 1;
+                               } else {
+                                       // We're in `WAITING_FOR_BATCH`, so we should wait until we're ready.
+                                       debug_assert!(flags.is_set(FundingSentFlags::WAITING_FOR_BATCH));
+                               }
+                       }
+                       // If we reconnected before sending our `channel_ready` they may still resend theirs.
+                       ChannelState::ChannelReady(_) => check_reconnection = true,
+                       _ => return Err(ChannelError::Close("Peer sent a channel_ready at a strange time".to_owned())),
+               }
+               if check_reconnection {
                        // They probably disconnected/reconnected and re-sent the channel_ready, which is
                        // required, or they're sending a fresh SCID alias.
                        let expected_point =
@@ -2883,8 +3118,6 @@ impl<SP: Deref> Channel<SP> where
                                return Err(ChannelError::Close("Peer sent a reconnect channel_ready with a different point".to_owned()));
                        }
                        return Ok(None);
-               } else {
-                       return Err(ChannelError::Close("Peer sent a channel_ready at a strange time".to_owned()));
                }
 
                self.context.counterparty_prev_commitment_point = self.context.counterparty_cur_commitment_point;
@@ -2902,17 +3135,18 @@ impl<SP: Deref> Channel<SP> where
        where F: for<'a> Fn(&'a Self, PendingHTLCStatus, u16) -> PendingHTLCStatus,
                FE::Target: FeeEstimator, L::Target: Logger,
        {
+               if !matches!(self.context.channel_state, ChannelState::ChannelReady(_)) {
+                       return Err(ChannelError::Close("Got add HTLC message when channel was not in an operational state".to_owned()));
+               }
                // We can't accept HTLCs sent after we've sent a shutdown.
-               let local_sent_shutdown = (self.context.channel_state & (ChannelState::ChannelReady as u32 | ChannelState::LocalShutdownSent as u32)) != (ChannelState::ChannelReady as u32);
-               if local_sent_shutdown {
+               if self.context.channel_state.is_local_shutdown_sent() {
                        pending_forward_status = create_pending_htlc_status(self, pending_forward_status, 0x4000|8);
                }
                // If the remote has sent a shutdown prior to adding this HTLC, then they are in violation of the spec.
-               let remote_sent_shutdown = (self.context.channel_state & (ChannelState::ChannelReady as u32 | ChannelState::RemoteShutdownSent as u32)) != (ChannelState::ChannelReady as u32);
-               if remote_sent_shutdown {
+               if self.context.channel_state.is_remote_shutdown_sent() {
                        return Err(ChannelError::Close("Got add HTLC message when channel was not in an operational state".to_owned()));
                }
-               if self.context.channel_state & (ChannelState::PeerDisconnected as u32) == ChannelState::PeerDisconnected as u32 {
+               if self.context.channel_state.is_peer_disconnected() {
                        return Err(ChannelError::Close("Peer sent update_add_htlc when we needed a channel_reestablish".to_owned()));
                }
                if msg.amount_msat > self.context.channel_value_satoshis * 1000 {
@@ -3047,7 +3281,7 @@ impl<SP: Deref> Channel<SP> where
                        return Err(ChannelError::Close("Remote provided CLTV expiry in seconds instead of block height".to_owned()));
                }
 
-               if self.context.channel_state & ChannelState::LocalShutdownSent as u32 != 0 {
+               if self.context.channel_state.is_local_shutdown_sent() {
                        if let PendingHTLCStatus::Forward(_) = pending_forward_status {
                                panic!("ChannelManager shouldn't be trying to add a forwardable HTLC after we've started closing");
                        }
@@ -3097,10 +3331,10 @@ impl<SP: Deref> Channel<SP> where
        }
 
        pub fn update_fulfill_htlc(&mut self, msg: &msgs::UpdateFulfillHTLC) -> Result<(HTLCSource, u64), ChannelError> {
-               if (self.context.channel_state & (ChannelState::ChannelReady as u32)) != (ChannelState::ChannelReady as u32) {
+               if !matches!(self.context.channel_state, ChannelState::ChannelReady(_)) {
                        return Err(ChannelError::Close("Got fulfill HTLC message when channel was not in an operational state".to_owned()));
                }
-               if self.context.channel_state & (ChannelState::PeerDisconnected as u32) == ChannelState::PeerDisconnected as u32 {
+               if self.context.channel_state.is_peer_disconnected() {
                        return Err(ChannelError::Close("Peer sent update_fulfill_htlc when we needed a channel_reestablish".to_owned()));
                }
 
@@ -3108,10 +3342,10 @@ impl<SP: Deref> Channel<SP> where
        }
 
        pub fn update_fail_htlc(&mut self, msg: &msgs::UpdateFailHTLC, fail_reason: HTLCFailReason) -> Result<(), ChannelError> {
-               if (self.context.channel_state & (ChannelState::ChannelReady as u32)) != (ChannelState::ChannelReady as u32) {
+               if !matches!(self.context.channel_state, ChannelState::ChannelReady(_)) {
                        return Err(ChannelError::Close("Got fail HTLC message when channel was not in an operational state".to_owned()));
                }
-               if self.context.channel_state & (ChannelState::PeerDisconnected as u32) == ChannelState::PeerDisconnected as u32 {
+               if self.context.channel_state.is_peer_disconnected() {
                        return Err(ChannelError::Close("Peer sent update_fail_htlc when we needed a channel_reestablish".to_owned()));
                }
 
@@ -3120,10 +3354,10 @@ impl<SP: Deref> Channel<SP> where
        }
 
        pub fn update_fail_malformed_htlc(&mut self, msg: &msgs::UpdateFailMalformedHTLC, fail_reason: HTLCFailReason) -> Result<(), ChannelError> {
-               if (self.context.channel_state & (ChannelState::ChannelReady as u32)) != (ChannelState::ChannelReady as u32) {
+               if !matches!(self.context.channel_state, ChannelState::ChannelReady(_)) {
                        return Err(ChannelError::Close("Got fail malformed HTLC message when channel was not in an operational state".to_owned()));
                }
-               if self.context.channel_state & (ChannelState::PeerDisconnected as u32) == ChannelState::PeerDisconnected as u32 {
+               if self.context.channel_state.is_peer_disconnected() {
                        return Err(ChannelError::Close("Peer sent update_fail_malformed_htlc when we needed a channel_reestablish".to_owned()));
                }
 
@@ -3134,13 +3368,13 @@ impl<SP: Deref> Channel<SP> where
        pub fn commitment_signed<L: Deref>(&mut self, msg: &msgs::CommitmentSigned, logger: &L) -> Result<Option<ChannelMonitorUpdate>, ChannelError>
                where L::Target: Logger
        {
-               if (self.context.channel_state & (ChannelState::ChannelReady as u32)) != (ChannelState::ChannelReady as u32) {
+               if !matches!(self.context.channel_state, ChannelState::ChannelReady(_)) {
                        return Err(ChannelError::Close("Got commitment signed message when channel was not in an operational state".to_owned()));
                }
-               if self.context.channel_state & (ChannelState::PeerDisconnected as u32) == ChannelState::PeerDisconnected as u32 {
+               if self.context.channel_state.is_peer_disconnected() {
                        return Err(ChannelError::Close("Peer sent commitment_signed when we needed a channel_reestablish".to_owned()));
                }
-               if self.context.channel_state & BOTH_SIDES_SHUTDOWN_MASK == BOTH_SIDES_SHUTDOWN_MASK && self.context.last_sent_closing_fee.is_some() {
+               if self.context.channel_state.is_both_sides_shutdown() && self.context.last_sent_closing_fee.is_some() {
                        return Err(ChannelError::Close("Peer sent commitment_signed after we'd started exchanging closing_signeds".to_owned()));
                }
 
@@ -3315,11 +3549,11 @@ impl<SP: Deref> Channel<SP> where
                // build_commitment_no_status_check() next which will reset this to RAAFirst.
                self.context.resend_order = RAACommitmentOrder::CommitmentFirst;
 
-               if (self.context.channel_state & ChannelState::MonitorUpdateInProgress as u32) != 0 {
+               if self.context.channel_state.is_monitor_update_in_progress() {
                        // In case we initially failed monitor updating without requiring a response, we need
                        // to make sure the RAA gets sent first.
                        self.context.monitor_pending_revoke_and_ack = true;
-                       if need_commitment && (self.context.channel_state & (ChannelState::AwaitingRemoteRevoke as u32)) == 0 {
+                       if need_commitment && !self.context.channel_state.is_awaiting_remote_revoke() {
                                // If we were going to send a commitment_signed after the RAA, go ahead and do all
                                // the corresponding HTLC status updates so that
                                // get_last_commitment_update_for_send includes the right HTLCs.
@@ -3335,7 +3569,7 @@ impl<SP: Deref> Channel<SP> where
                        return Ok(self.push_ret_blockable_mon_update(monitor_update));
                }
 
-               let need_commitment_signed = if need_commitment && (self.context.channel_state & (ChannelState::AwaitingRemoteRevoke as u32)) == 0 {
+               let need_commitment_signed = if need_commitment && !self.context.channel_state.is_awaiting_remote_revoke() {
                        // 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().
@@ -3361,8 +3595,7 @@ impl<SP: Deref> Channel<SP> where
        ) -> (Option<ChannelMonitorUpdate>, Vec<(HTLCSource, PaymentHash)>)
        where F::Target: FeeEstimator, L::Target: Logger
        {
-               if self.context.channel_state & !STATE_FLAGS >= ChannelState::ChannelReady as u32 &&
-                  (self.context.channel_state & (ChannelState::AwaitingRemoteRevoke as u32 | ChannelState::PeerDisconnected as u32 | ChannelState::MonitorUpdateInProgress as u32)) == 0 {
+               if matches!(self.context.channel_state, ChannelState::ChannelReady(_)) && !self.context.channel_state.should_force_holding_cell() {
                        self.free_holding_cell_htlcs(fee_estimator, logger)
                } else { (None, Vec::new()) }
        }
@@ -3374,7 +3607,7 @@ impl<SP: Deref> Channel<SP> where
        ) -> (Option<ChannelMonitorUpdate>, Vec<(HTLCSource, PaymentHash)>)
        where F::Target: FeeEstimator, L::Target: Logger
        {
-               assert_eq!(self.context.channel_state & ChannelState::MonitorUpdateInProgress as u32, 0);
+               assert!(!self.context.channel_state.is_monitor_update_in_progress());
                if self.context.holding_cell_htlc_updates.len() != 0 || self.context.holding_cell_update_fee.is_some() {
                        log_trace!(logger, "Freeing holding cell with {} HTLC updates{} in channel {}", self.context.holding_cell_htlc_updates.len(),
                                if self.context.holding_cell_update_fee.is_some() { " and a fee update" } else { "" }, &self.context.channel_id());
@@ -3495,13 +3728,13 @@ impl<SP: Deref> Channel<SP> where
        ) -> Result<(Vec<(HTLCSource, PaymentHash)>, Option<ChannelMonitorUpdate>), ChannelError>
        where F::Target: FeeEstimator, L::Target: Logger,
        {
-               if (self.context.channel_state & (ChannelState::ChannelReady as u32)) != (ChannelState::ChannelReady as u32) {
+               if !matches!(self.context.channel_state, ChannelState::ChannelReady(_)) {
                        return Err(ChannelError::Close("Got revoke/ACK message when channel was not in an operational state".to_owned()));
                }
-               if self.context.channel_state & (ChannelState::PeerDisconnected as u32) == ChannelState::PeerDisconnected as u32 {
+               if self.context.channel_state.is_peer_disconnected() {
                        return Err(ChannelError::Close("Peer sent revoke_and_ack when we needed a channel_reestablish".to_owned()));
                }
-               if self.context.channel_state & BOTH_SIDES_SHUTDOWN_MASK == BOTH_SIDES_SHUTDOWN_MASK && self.context.last_sent_closing_fee.is_some() {
+               if self.context.channel_state.is_both_sides_shutdown() && self.context.last_sent_closing_fee.is_some() {
                        return Err(ChannelError::Close("Peer sent revoke_and_ack after we'd started exchanging closing_signeds".to_owned()));
                }
 
@@ -3513,7 +3746,7 @@ impl<SP: Deref> Channel<SP> where
                        }
                }
 
-               if self.context.channel_state & ChannelState::AwaitingRemoteRevoke as u32 == 0 {
+               if !self.context.channel_state.is_awaiting_remote_revoke() {
                        // Our counterparty seems to have burned their coins to us (by revoking a state when we
                        // haven't given them a new commitment transaction to broadcast). We should probably
                        // take advantage of this by updating our channel monitor, sending them an error, and
@@ -3557,7 +3790,7 @@ impl<SP: Deref> Channel<SP> where
                // (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.context.channel_state &= !(ChannelState::AwaitingRemoteRevoke as u32);
+               self.context.channel_state.clear_awaiting_remote_revoke();
                self.context.sent_message_awaiting_response = None;
                self.context.counterparty_prev_commitment_point = self.context.counterparty_cur_commitment_point;
                self.context.counterparty_cur_commitment_point = Some(msg.next_per_commitment_point);
@@ -3699,7 +3932,7 @@ impl<SP: Deref> Channel<SP> where
                        }
                }
 
-               if (self.context.channel_state & ChannelState::MonitorUpdateInProgress as u32) == ChannelState::MonitorUpdateInProgress as u32 {
+               if self.context.channel_state.is_monitor_update_in_progress() {
                        // We can't actually generate a new commitment transaction (incl by freeing holding
                        // cells) while we can't update the monitor, so we just return what we have.
                        if require_commitment {
@@ -3821,7 +4054,7 @@ impl<SP: Deref> Channel<SP> where
                        return None;
                }
 
-               if (self.context.channel_state & (ChannelState::AwaitingRemoteRevoke as u32 | ChannelState::MonitorUpdateInProgress as u32)) != 0 {
+               if self.context.channel_state.is_awaiting_remote_revoke() || self.context.channel_state.is_monitor_update_in_progress() {
                        force_holding_cell = true;
                }
 
@@ -3846,12 +4079,12 @@ impl<SP: Deref> Channel<SP> where
        /// completed.
        /// May return `Err(())`, which implies [`ChannelContext::force_shutdown`] should be called immediately.
        pub fn remove_uncommitted_htlcs_and_mark_paused<L: Deref>(&mut self, logger: &L) -> Result<(), ()> where L::Target: Logger {
-               assert_eq!(self.context.channel_state & ChannelState::ShutdownComplete as u32, 0);
-               if self.context.channel_state & !STATE_FLAGS < ChannelState::FundingSent as u32 {
-                       return Err(());
+               assert!(!matches!(self.context.channel_state, ChannelState::ShutdownComplete));
+               if self.context.channel_state.is_pre_funded_state() {
+                       return Err(())
                }
 
-               if self.context.channel_state & (ChannelState::PeerDisconnected as u32) == (ChannelState::PeerDisconnected as u32) {
+               if self.context.channel_state.is_peer_disconnected() {
                        // While the below code should be idempotent, it's simpler to just return early, as
                        // redundant disconnect events can fire, though they should be rare.
                        return Ok(());
@@ -3913,7 +4146,7 @@ impl<SP: Deref> Channel<SP> where
 
                self.context.sent_message_awaiting_response = None;
 
-               self.context.channel_state |= ChannelState::PeerDisconnected as u32;
+               self.context.channel_state.set_peer_disconnected();
                log_trace!(logger, "Peer disconnection resulted in {} remote-announced HTLC drops on channel {}", inbound_drop_count, &self.context.channel_id());
                Ok(())
        }
@@ -3940,7 +4173,7 @@ impl<SP: Deref> Channel<SP> where
                self.context.monitor_pending_forwards.append(&mut pending_forwards);
                self.context.monitor_pending_failures.append(&mut pending_fails);
                self.context.monitor_pending_finalized_fulfills.append(&mut pending_finalized_claimed_htlcs);
-               self.context.channel_state |= ChannelState::MonitorUpdateInProgress as u32;
+               self.context.channel_state.set_monitor_update_in_progress();
        }
 
        /// Indicates that the latest ChannelMonitor update has been committed by the client
@@ -3954,19 +4187,22 @@ impl<SP: Deref> Channel<SP> where
                L::Target: Logger,
                NS::Target: NodeSigner
        {
-               assert_eq!(self.context.channel_state & ChannelState::MonitorUpdateInProgress as u32, ChannelState::MonitorUpdateInProgress as u32);
-               self.context.channel_state &= !(ChannelState::MonitorUpdateInProgress as u32);
+               assert!(self.context.channel_state.is_monitor_update_in_progress());
+               self.context.channel_state.clear_monitor_update_in_progress();
 
                // If we're past (or at) the FundingSent stage on an outbound channel, try to
                // (re-)broadcast the funding transaction as we may have declined to broadcast it when we
                // first received the funding_signed.
                let mut funding_broadcastable =
-                       if self.context.is_outbound() && self.context.channel_state & !STATE_FLAGS >= ChannelState::FundingSent as u32 && self.context.channel_state & ChannelState::WaitingForBatch as u32 == 0 {
+                       if self.context.is_outbound() &&
+                               matches!(self.context.channel_state, ChannelState::FundingSent(flags) if !flags.is_set(FundingSentFlags::WAITING_FOR_BATCH)) ||
+                               matches!(self.context.channel_state, ChannelState::ChannelReady(_))
+                       {
                                self.context.funding_transaction.take()
                        } else { None };
                // That said, if the funding transaction is already confirmed (ie we're active with a
                // minimum_depth over 0) don't bother re-broadcasting the confirmed funding tx.
-               if self.context.channel_state & !STATE_FLAGS >= ChannelState::ChannelReady as u32 && self.context.minimum_depth != Some(0) {
+               if matches!(self.context.channel_state, ChannelState::ChannelReady(_)) && self.context.minimum_depth != Some(0) {
                        funding_broadcastable = None;
                }
 
@@ -3997,7 +4233,7 @@ impl<SP: Deref> Channel<SP> where
                let mut finalized_claimed_htlcs = Vec::new();
                mem::swap(&mut finalized_claimed_htlcs, &mut self.context.monitor_pending_finalized_fulfills);
 
-               if self.context.channel_state & (ChannelState::PeerDisconnected as u32) != 0 {
+               if self.context.channel_state.is_peer_disconnected() {
                        self.context.monitor_pending_revoke_and_ack = false;
                        self.context.monitor_pending_commitment_signed = false;
                        return MonitorRestoreUpdates {
@@ -4034,7 +4270,7 @@ impl<SP: Deref> Channel<SP> where
                if self.context.is_outbound() {
                        return Err(ChannelError::Close("Non-funding remote tried to update channel fee".to_owned()));
                }
-               if self.context.channel_state & (ChannelState::PeerDisconnected as u32) == ChannelState::PeerDisconnected as u32 {
+               if self.context.channel_state.is_peer_disconnected() {
                        return Err(ChannelError::Close("Peer sent update_fee when we needed a channel_reestablish".to_owned()));
                }
                Channel::<SP>::check_remote_fee(&self.context.channel_type, fee_estimator, msg.feerate_per_kw, Some(self.context.feerate_per_kw), logger)?;
@@ -4185,7 +4421,7 @@ impl<SP: Deref> Channel<SP> where
 
        /// Gets the `Shutdown` message we should send our peer on reconnect, if any.
        pub fn get_outbound_shutdown(&self) -> Option<msgs::Shutdown> {
-               if self.context.channel_state & (ChannelState::LocalShutdownSent as u32) != 0 {
+               if self.context.channel_state.is_local_shutdown_sent() {
                        assert!(self.context.shutdown_scriptpubkey.is_some());
                        Some(msgs::Shutdown {
                                channel_id: self.context.channel_id,
@@ -4209,7 +4445,7 @@ impl<SP: Deref> Channel<SP> where
                L::Target: Logger,
                NS::Target: NodeSigner
        {
-               if self.context.channel_state & (ChannelState::PeerDisconnected as u32) == 0 {
+               if !self.context.channel_state.is_peer_disconnected() {
                        // While BOLT 2 doesn't indicate explicitly we should error this channel here, it
                        // almost certainly indicates we are going to end up out-of-sync in some way, so we
                        // just close here instead of trying to recover.
@@ -4259,17 +4495,17 @@ impl<SP: Deref> Channel<SP> where
 
                // Go ahead and unmark PeerDisconnected as various calls we may make check for it (and all
                // remaining cases either succeed or ErrorMessage-fail).
-               self.context.channel_state &= !(ChannelState::PeerDisconnected as u32);
+               self.context.channel_state.clear_peer_disconnected();
                self.context.sent_message_awaiting_response = None;
 
                let shutdown_msg = self.get_outbound_shutdown();
 
                let announcement_sigs = self.get_announcement_sigs(node_signer, chain_hash, user_config, best_block.height(), logger);
 
-               if self.context.channel_state & (ChannelState::FundingSent as u32) == ChannelState::FundingSent as u32 {
+               if matches!(self.context.channel_state, ChannelState::FundingSent(_)) {
                        // If we're waiting on a monitor update, we shouldn't re-send any channel_ready's.
-                       if self.context.channel_state & (ChannelState::OurChannelReady as u32) == 0 ||
-                                       self.context.channel_state & (ChannelState::MonitorUpdateInProgress as u32) != 0 {
+                       if !self.context.channel_state.is_our_channel_ready() ||
+                                       self.context.channel_state.is_monitor_update_in_progress() {
                                if msg.next_remote_commitment_number != 0 {
                                        return Err(ChannelError::Close("Peer claimed they saw a revoke_and_ack but we haven't sent channel_ready yet".to_owned()));
                                }
@@ -4301,7 +4537,7 @@ impl<SP: Deref> Channel<SP> where
                        // Note that if we need to repeat our ChannelReady we'll do that in the next if block.
                        None
                } else if msg.next_remote_commitment_number + 1 == our_commitment_transaction {
-                       if self.context.channel_state & (ChannelState::MonitorUpdateInProgress as u32) != 0 {
+                       if self.context.channel_state.is_monitor_update_in_progress() {
                                self.context.monitor_pending_revoke_and_ack = true;
                                None
                        } else {
@@ -4320,7 +4556,7 @@ impl<SP: Deref> Channel<SP> where
                // revoke_and_ack, not on sending commitment_signed, so we add one if have
                // AwaitingRemoteRevoke set, which indicates we sent a commitment_signed but haven't gotten
                // the corresponding revoke_and_ack back yet.
-               let is_awaiting_remote_revoke = self.context.channel_state & ChannelState::AwaitingRemoteRevoke as u32 != 0;
+               let is_awaiting_remote_revoke = self.context.channel_state.is_awaiting_remote_revoke();
                if is_awaiting_remote_revoke && !self.is_awaiting_monitor_update() {
                        self.mark_awaiting_response();
                }
@@ -4356,7 +4592,7 @@ impl<SP: Deref> Channel<SP> where
                                log_debug!(logger, "Reconnected channel {} with only lost remote commitment tx", &self.context.channel_id());
                        }
 
-                       if self.context.channel_state & (ChannelState::MonitorUpdateInProgress as u32) != 0 {
+                       if self.context.channel_state.is_monitor_update_in_progress() {
                                self.context.monitor_pending_commitment_signed = true;
                                Ok(ReestablishResponses {
                                        channel_ready, shutdown_msg, announcement_sigs,
@@ -4543,10 +4779,10 @@ impl<SP: Deref> Channel<SP> where
                &mut self, signer_provider: &SP, their_features: &InitFeatures, msg: &msgs::Shutdown
        ) -> Result<(Option<msgs::Shutdown>, Option<ChannelMonitorUpdate>, Vec<(HTLCSource, PaymentHash)>), ChannelError>
        {
-               if self.context.channel_state & (ChannelState::PeerDisconnected as u32) == ChannelState::PeerDisconnected as u32 {
+               if self.context.channel_state.is_peer_disconnected() {
                        return Err(ChannelError::Close("Peer sent shutdown when we needed a channel_reestablish".to_owned()));
                }
-               if self.context.channel_state & !STATE_FLAGS < ChannelState::FundingSent as u32 {
+               if self.context.channel_state.is_pre_funded_state() {
                        // Spec says we should fail the connection, not the channel, but that's nonsense, there
                        // are plenty of reasons you may want to fail a channel pre-funding, and spec says you
                        // can do that via error message without getting a connection fail anyway...
@@ -4557,7 +4793,7 @@ impl<SP: Deref> Channel<SP> where
                                return Err(ChannelError::Close("Got shutdown with remote pending HTLCs".to_owned()));
                        }
                }
-               assert_eq!(self.context.channel_state & ChannelState::ShutdownComplete as u32, 0);
+               assert!(!matches!(self.context.channel_state, ChannelState::ShutdownComplete));
 
                if !script::is_bolt2_compliant(&msg.scriptpubkey, their_features) {
                        return Err(ChannelError::Warn(format!("Got a nonstandard scriptpubkey ({}) from remote peer", msg.scriptpubkey.to_hex_string())));
@@ -4574,7 +4810,7 @@ impl<SP: Deref> Channel<SP> where
                // If we have any LocalAnnounced updates we'll probably just get back an update_fail_htlc
                // immediately after the commitment dance, but we can send a Shutdown because we won't send
                // any further commitment updates after we set LocalShutdownSent.
-               let send_shutdown = (self.context.channel_state & ChannelState::LocalShutdownSent as u32) != ChannelState::LocalShutdownSent as u32;
+               let send_shutdown = !self.context.channel_state.is_local_shutdown_sent();
 
                let update_shutdown_script = match self.context.shutdown_scriptpubkey {
                        Some(_) => false,
@@ -4594,7 +4830,7 @@ impl<SP: Deref> Channel<SP> where
 
                // From here on out, we may not fail!
 
-               self.context.channel_state |= ChannelState::RemoteShutdownSent as u32;
+               self.context.channel_state.set_remote_shutdown_sent();
                self.context.update_time_counter += 1;
 
                let monitor_update = if update_shutdown_script {
@@ -4630,7 +4866,7 @@ impl<SP: Deref> Channel<SP> where
                        }
                });
 
-               self.context.channel_state |= ChannelState::LocalShutdownSent as u32;
+               self.context.channel_state.set_local_shutdown_sent();
                self.context.update_time_counter += 1;
 
                Ok((shutdown, monitor_update, dropped_outbound_htlcs))
@@ -4664,10 +4900,10 @@ impl<SP: Deref> Channel<SP> where
                -> Result<(Option<msgs::ClosingSigned>, Option<Transaction>, Option<ShutdownResult>), ChannelError>
                where F::Target: FeeEstimator
        {
-               if self.context.channel_state & BOTH_SIDES_SHUTDOWN_MASK != BOTH_SIDES_SHUTDOWN_MASK {
+               if !self.context.channel_state.is_both_sides_shutdown() {
                        return Err(ChannelError::Close("Remote end sent us a closing_signed before both sides provided a shutdown".to_owned()));
                }
-               if self.context.channel_state & (ChannelState::PeerDisconnected as u32) == ChannelState::PeerDisconnected as u32 {
+               if self.context.channel_state.is_peer_disconnected() {
                        return Err(ChannelError::Close("Peer sent closing_signed when we needed a channel_reestablish".to_owned()));
                }
                if !self.context.pending_inbound_htlcs.is_empty() || !self.context.pending_outbound_htlcs.is_empty() {
@@ -4681,7 +4917,7 @@ impl<SP: Deref> Channel<SP> where
                        return Err(ChannelError::Close("Remote tried to send a closing_signed when we were supposed to propose the first one".to_owned()));
                }
 
-               if self.context.channel_state & ChannelState::MonitorUpdateInProgress as u32 != 0 {
+               if self.context.channel_state.is_monitor_update_in_progress() {
                        self.context.pending_counterparty_closing_signed = Some(msg.clone());
                        return Ok((None, None, None));
                }
@@ -4721,7 +4957,7 @@ impl<SP: Deref> Channel<SP> where
                                        counterparty_node_id: self.context.counterparty_node_id,
                                };
                                let tx = self.build_signed_closing_transaction(&mut closing_tx, &msg.signature, &sig);
-                               self.context.channel_state = ChannelState::ShutdownComplete as u32;
+                               self.context.channel_state = ChannelState::ShutdownComplete;
                                self.context.update_time_counter += 1;
                                return Ok((None, Some(tx), Some(shutdown_result)));
                        }
@@ -4750,7 +4986,7 @@ impl<SP: Deref> Channel<SP> where
                                                                channel_id: self.context.channel_id,
                                                                counterparty_node_id: self.context.counterparty_node_id,
                                                        };
-                                                       self.context.channel_state = ChannelState::ShutdownComplete as u32;
+                                                       self.context.channel_state = ChannelState::ShutdownComplete;
                                                        self.context.update_time_counter += 1;
                                                        let tx = self.build_signed_closing_transaction(&closing_tx, &msg.signature, &sig);
                                                        (Some(tx), Some(shutdown_result))
@@ -4875,7 +5111,7 @@ impl<SP: Deref> Channel<SP> where
        }
 
        pub fn get_cur_counterparty_commitment_transaction_number(&self) -> u64 {
-               self.context.cur_counterparty_commitment_transaction_number + 1 - if self.context.channel_state & (ChannelState::AwaitingRemoteRevoke as u32) != 0 { 1 } else { 0 }
+               self.context.cur_counterparty_commitment_transaction_number + 1 - if self.context.channel_state.is_awaiting_remote_revoke() { 1 } else { 0 }
        }
 
        pub fn get_revoked_counterparty_commitment_transaction_number(&self) -> u64 {
@@ -4915,7 +5151,7 @@ impl<SP: Deref> Channel<SP> where
        /// Returns true if this channel has been marked as awaiting a monitor update to move forward.
        /// Allowed in any state (including after shutdown)
        pub fn is_awaiting_monitor_update(&self) -> bool {
-               (self.context.channel_state & ChannelState::MonitorUpdateInProgress as u32) != 0
+               self.context.channel_state.is_monitor_update_in_progress()
        }
 
        /// Gets the latest [`ChannelMonitorUpdate`] ID which has been released and is in-flight.
@@ -4957,9 +5193,10 @@ impl<SP: Deref> Channel<SP> where
        /// advanced state.
        pub fn is_awaiting_initial_mon_persist(&self) -> bool {
                if !self.is_awaiting_monitor_update() { return false; }
-               if self.context.channel_state &
-                       !(ChannelState::TheirChannelReady as u32 | ChannelState::PeerDisconnected as u32 | ChannelState::MonitorUpdateInProgress as u32 | ChannelState::WaitingForBatch as u32)
-                               == ChannelState::FundingSent as u32 {
+               if matches!(
+                       self.context.channel_state, ChannelState::FundingSent(flags)
+                       if (flags & !(FundingSentFlags::THEIR_CHANNEL_READY | FundedStateFlags::PEER_DISCONNECTED | FundedStateFlags::MONITOR_UPDATE_IN_PROGRESS | FundingSentFlags::WAITING_FOR_BATCH)).is_empty()
+               ) {
                        // If we're not a 0conf channel, we'll be waiting on a monitor update with only
                        // FundingSent set, though our peer could have sent their channel_ready.
                        debug_assert!(self.context.minimum_depth.unwrap_or(1) > 0);
@@ -4989,27 +5226,25 @@ impl<SP: Deref> Channel<SP> where
 
        /// Returns true if our channel_ready has been sent
        pub fn is_our_channel_ready(&self) -> bool {
-               (self.context.channel_state & ChannelState::OurChannelReady as u32) != 0 || self.context.channel_state & !STATE_FLAGS >= ChannelState::ChannelReady as u32
+               matches!(self.context.channel_state, ChannelState::FundingSent(flags) if flags.is_set(FundingSentFlags::OUR_CHANNEL_READY)) ||
+                       matches!(self.context.channel_state, ChannelState::ChannelReady(_))
        }
 
        /// Returns true if our peer has either initiated or agreed to shut down the channel.
        pub fn received_shutdown(&self) -> bool {
-               (self.context.channel_state & ChannelState::RemoteShutdownSent as u32) != 0
+               self.context.channel_state.is_remote_shutdown_sent()
        }
 
        /// Returns true if we either initiated or agreed to shut down the channel.
        pub fn sent_shutdown(&self) -> bool {
-               (self.context.channel_state & ChannelState::LocalShutdownSent as u32) != 0
+               self.context.channel_state.is_local_shutdown_sent()
        }
 
        /// 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.context.channel_state & ChannelState::ShutdownComplete as u32) == ChannelState::ShutdownComplete as u32  {
-                       assert!(self.context.channel_state == ChannelState::ShutdownComplete as u32);
-                       true
-               } else { false }
+               matches!(self.context.channel_state, ChannelState::ShutdownComplete)
        }
 
        pub fn channel_update_status(&self) -> ChannelUpdateStatus {
@@ -5046,19 +5281,20 @@ impl<SP: Deref> Channel<SP> where
 
                // Note that we don't include ChannelState::WaitingForBatch as we don't want to send
                // channel_ready until the entire batch is ready.
-               let non_shutdown_state = self.context.channel_state & (!MULTI_STATE_FLAGS);
-               let need_commitment_update = if non_shutdown_state == ChannelState::FundingSent as u32 {
-                       self.context.channel_state |= ChannelState::OurChannelReady as u32;
+               let need_commitment_update = if matches!(self.context.channel_state, ChannelState::FundingSent(f) if (f & !FundedStateFlags::ALL).is_empty()) {
+                       self.context.channel_state.set_our_channel_ready();
                        true
-               } else if non_shutdown_state == (ChannelState::FundingSent as u32 | ChannelState::TheirChannelReady as u32) {
-                       self.context.channel_state = ChannelState::ChannelReady as u32 | (self.context.channel_state & MULTI_STATE_FLAGS);
+               } else if matches!(self.context.channel_state, ChannelState::FundingSent(f) if f & !FundedStateFlags::ALL == FundingSentFlags::THEIR_CHANNEL_READY) {
+                       self.context.channel_state = ChannelState::ChannelReady(self.context.channel_state.with_funded_state_flags_mask().into());
                        self.context.update_time_counter += 1;
                        true
-               } else if non_shutdown_state == (ChannelState::FundingSent as u32 | ChannelState::OurChannelReady as u32) {
+               } else if matches!(self.context.channel_state, ChannelState::FundingSent(f) if f & !FundedStateFlags::ALL == FundingSentFlags::OUR_CHANNEL_READY) {
                        // We got a reorg but not enough to trigger a force close, just ignore.
                        false
                } else {
-                       if self.context.funding_tx_confirmation_height != 0 && self.context.channel_state & !STATE_FLAGS < ChannelState::ChannelReady as u32 {
+                       if self.context.funding_tx_confirmation_height != 0 &&
+                               self.context.channel_state < ChannelState::ChannelReady(ChannelReadyFlags::new())
+                       {
                                // We should never see a funding transaction on-chain until we've received
                                // funding_signed (if we're an outbound channel), or seen funding_generated (if we're
                                // an inbound channel - before that we have no known funding TXID). The fuzzer,
@@ -5066,15 +5302,15 @@ impl<SP: Deref> Channel<SP> where
                                #[cfg(not(fuzzing))]
                                panic!("Started confirming a channel in a state pre-FundingSent: {}.\n\
                                        Do NOT broadcast a funding transaction manually - let LDK do it for you!",
-                                       self.context.channel_state);
+                                       self.context.channel_state.to_u32());
                        }
                        // We got a reorg but not enough to trigger a force close, just ignore.
                        false
                };
 
                if need_commitment_update {
-                       if self.context.channel_state & (ChannelState::MonitorUpdateInProgress as u32) == 0 {
-                               if self.context.channel_state & (ChannelState::PeerDisconnected as u32) == 0 {
+                       if !self.context.channel_state.is_monitor_update_in_progress() {
+                               if !self.context.channel_state.is_peer_disconnected() {
                                        let next_per_commitment_point =
                                                self.context.holder_signer.as_ref().get_per_commitment_point(INITIAL_COMMITMENT_NUMBER - 1, &self.context.secp_ctx);
                                        return Some(msgs::ChannelReady {
@@ -5228,9 +5464,8 @@ impl<SP: Deref> Channel<SP> where
                        return Ok((Some(channel_ready), timed_out_htlcs, announcement_sigs));
                }
 
-               let non_shutdown_state = self.context.channel_state & (!MULTI_STATE_FLAGS);
-               if non_shutdown_state & !STATE_FLAGS >= ChannelState::ChannelReady as u32 ||
-                  (non_shutdown_state & ChannelState::OurChannelReady as u32) == ChannelState::OurChannelReady as u32 {
+               if matches!(self.context.channel_state, ChannelState::ChannelReady(_)) ||
+                       self.context.channel_state.is_our_channel_ready() {
                        let mut funding_tx_confirmations = height as i64 - self.context.funding_tx_confirmation_height as i64 + 1;
                        if self.context.funding_tx_confirmation_height == 0 {
                                // Note that check_get_channel_ready may reset funding_tx_confirmation_height to
@@ -5257,8 +5492,8 @@ impl<SP: Deref> Channel<SP> where
                                height >= self.context.channel_creation_height + FUNDING_CONF_DEADLINE_BLOCKS {
                        log_info!(logger, "Closing channel {} due to funding timeout", &self.context.channel_id);
                        // If funding_tx_confirmed_in is unset, the channel must not be active
-                       assert!(non_shutdown_state & !STATE_FLAGS <= ChannelState::ChannelReady as u32);
-                       assert_eq!(non_shutdown_state & ChannelState::OurChannelReady as u32, 0);
+                       assert!(self.context.channel_state <= ChannelState::ChannelReady(ChannelReadyFlags::new()));
+                       assert!(!self.context.channel_state.is_our_channel_ready());
                        return Err(ClosureReason::FundingTimedOut);
                }
 
@@ -5356,7 +5591,7 @@ impl<SP: Deref> Channel<SP> where
                        return None;
                }
 
-               if self.context.channel_state & ChannelState::PeerDisconnected as u32 != 0 {
+               if self.context.channel_state.is_peer_disconnected() {
                        log_trace!(logger, "Cannot create an announcement_signatures as our peer is disconnected");
                        return None;
                }
@@ -5494,7 +5729,7 @@ impl<SP: Deref> Channel<SP> where
        /// May panic if called on a channel that wasn't immediately-previously
        /// self.remove_uncommitted_htlcs_and_mark_paused()'d
        pub fn get_channel_reestablish<L: Deref>(&mut self, logger: &L) -> msgs::ChannelReestablish where L::Target: Logger {
-               assert_eq!(self.context.channel_state & ChannelState::PeerDisconnected as u32, ChannelState::PeerDisconnected as u32);
+               assert!(self.context.channel_state.is_peer_disconnected());
                assert_ne!(self.context.cur_counterparty_commitment_transaction_number, INITIAL_COMMITMENT_NUMBER);
                // Prior to static_remotekey, my_current_per_commitment_point was critical to claiming
                // current to_remote balances. However, it no longer has any use, and thus is now simply
@@ -5592,7 +5827,10 @@ impl<SP: Deref> Channel<SP> where
        ) -> Result<Option<msgs::UpdateAddHTLC>, ChannelError>
        where F::Target: FeeEstimator, L::Target: Logger
        {
-               if (self.context.channel_state & (ChannelState::ChannelReady as u32 | BOTH_SIDES_SHUTDOWN_MASK)) != (ChannelState::ChannelReady as u32) {
+               if !matches!(self.context.channel_state, ChannelState::ChannelReady(_)) ||
+                       self.context.channel_state.is_local_shutdown_sent() ||
+                       self.context.channel_state.is_remote_shutdown_sent()
+               {
                        return Err(ChannelError::Ignore("Cannot send HTLC until channel is fully established and we haven't started shutting down".to_owned()));
                }
                let channel_total_msat = self.context.channel_value_satoshis * 1000;
@@ -5615,7 +5853,7 @@ impl<SP: Deref> Channel<SP> where
                                available_balances.next_outbound_htlc_limit_msat)));
                }
 
-               if (self.context.channel_state & (ChannelState::PeerDisconnected as u32)) != 0 {
+               if self.context.channel_state.is_peer_disconnected() {
                        // Note that this should never really happen, if we're !is_live() on receipt of an
                        // incoming HTLC for relay will result in us rejecting the HTLC and we won't allow
                        // the user to send directly into a !is_live() channel. However, if we
@@ -5625,7 +5863,7 @@ impl<SP: Deref> Channel<SP> where
                        return Err(ChannelError::Ignore("Cannot send an HTLC while disconnected from channel counterparty".to_owned()));
                }
 
-               let need_holding_cell = (self.context.channel_state & (ChannelState::AwaitingRemoteRevoke as u32 | ChannelState::MonitorUpdateInProgress as u32)) != 0;
+               let need_holding_cell = self.context.channel_state.should_force_holding_cell();
                log_debug!(logger, "Pushing new outbound HTLC with hash {} for {} msat {}",
                        payment_hash, amount_msat,
                        if force_holding_cell { "into holding cell" }
@@ -5732,7 +5970,7 @@ impl<SP: Deref> Channel<SP> where
                                to_countersignatory_value_sat: Some(counterparty_commitment_tx.to_countersignatory_value_sat()),
                        }]
                };
-               self.context.channel_state |= ChannelState::AwaitingRemoteRevoke as u32;
+               self.context.channel_state.set_awaiting_remote_revoke();
                monitor_update
        }
 
@@ -5878,26 +6116,24 @@ impl<SP: Deref> Channel<SP> where
                                return Err(APIError::APIMisuseError{err: "Cannot begin shutdown with pending HTLCs. Process pending events first".to_owned()});
                        }
                }
-               if self.context.channel_state & BOTH_SIDES_SHUTDOWN_MASK != 0 {
-                       if (self.context.channel_state & ChannelState::LocalShutdownSent as u32) == ChannelState::LocalShutdownSent as u32 {
-                               return Err(APIError::APIMisuseError{err: "Shutdown already in progress".to_owned()});
-                       }
-                       else if (self.context.channel_state & ChannelState::RemoteShutdownSent as u32) == ChannelState::RemoteShutdownSent as u32 {
-                               return Err(APIError::ChannelUnavailable{err: "Shutdown already in progress by remote".to_owned()});
-                       }
+               if self.context.channel_state.is_local_shutdown_sent() {
+                       return Err(APIError::APIMisuseError{err: "Shutdown already in progress".to_owned()});
+               }
+               else if self.context.channel_state.is_remote_shutdown_sent() {
+                       return Err(APIError::ChannelUnavailable{err: "Shutdown already in progress by remote".to_owned()});
                }
                if self.context.shutdown_scriptpubkey.is_some() && override_shutdown_script.is_some() {
                        return Err(APIError::APIMisuseError{err: "Cannot override shutdown script for a channel with one already set".to_owned()});
                }
-               assert_eq!(self.context.channel_state & ChannelState::ShutdownComplete as u32, 0);
-               if self.context.channel_state & (ChannelState::PeerDisconnected as u32 | ChannelState::MonitorUpdateInProgress as u32) != 0 {
+               assert!(!matches!(self.context.channel_state, ChannelState::ShutdownComplete));
+               if self.context.channel_state.is_peer_disconnected() || self.context.channel_state.is_monitor_update_in_progress() {
                        return Err(APIError::ChannelUnavailable{err: "Cannot begin shutdown while peer is disconnected or we're waiting on a monitor update, maybe force-close instead?".to_owned()});
                }
 
                // If we haven't funded the channel yet, we don't need to bother ensuring the shutdown
                // script is set, we just force-close and call it a day.
                let mut chan_closed = false;
-               if self.context.channel_state & !STATE_FLAGS < ChannelState::FundingSent as u32 {
+               if self.context.channel_state.is_pre_funded_state() {
                        chan_closed = true;
                }
 
@@ -5926,7 +6162,7 @@ impl<SP: Deref> Channel<SP> where
 
                // From here on out, we may not fail!
                self.context.target_closing_feerate_sats_per_kw = target_feerate_sats_per_kw;
-               let shutdown_result = if self.context.channel_state & !STATE_FLAGS < ChannelState::FundingSent as u32 {
+               let shutdown_result = if self.context.channel_state.is_pre_funded_state() {
                        let shutdown_result = ShutdownResult {
                                monitor_update: None,
                                dropped_outbound_htlcs: Vec::new(),
@@ -5934,10 +6170,10 @@ impl<SP: Deref> Channel<SP> where
                                channel_id: self.context.channel_id,
                                counterparty_node_id: self.context.counterparty_node_id,
                        };
-                       self.context.channel_state = ChannelState::ShutdownComplete as u32;
+                       self.context.channel_state = ChannelState::ShutdownComplete;
                        Some(shutdown_result)
                } else {
-                       self.context.channel_state |= ChannelState::LocalShutdownSent as u32;
+                       self.context.channel_state.set_local_shutdown_sent();
                        None
                };
                self.context.update_time_counter += 1;
@@ -6086,7 +6322,7 @@ impl<SP: Deref> OutboundV1Channel<SP> where SP::Target: SignerProvider {
 
                                channel_id: temporary_channel_id,
                                temporary_channel_id: Some(temporary_channel_id),
-                               channel_state: ChannelState::OurInitSent as u32,
+                               channel_state: ChannelState::NegotiatingFunding(NegotiatingFundingFlags::OUR_INIT_SENT),
                                announcement_sigs_state: AnnouncementSigsState::NotSent,
                                secp_ctx,
                                channel_value_satoshis,
@@ -6215,7 +6451,10 @@ impl<SP: Deref> OutboundV1Channel<SP> where SP::Target: SignerProvider {
                if !self.context.is_outbound() {
                        panic!("Tried to create outbound funding_created message on an inbound channel!");
                }
-               if self.context.channel_state != (ChannelState::OurInitSent as u32 | ChannelState::TheirInitSent as u32) {
+               if !matches!(
+                       self.context.channel_state, ChannelState::NegotiatingFunding(flags)
+                       if flags == (NegotiatingFundingFlags::OUR_INIT_SENT | NegotiatingFundingFlags::THEIR_INIT_SENT)
+               ) {
                        panic!("Tried to get a funding_created messsage at a time other than immediately after initial handshake completion (or tried to get funding_created twice)");
                }
                if self.context.commitment_secrets.get_min_seen_secret() != (1 << 48) ||
@@ -6229,7 +6468,7 @@ impl<SP: Deref> OutboundV1Channel<SP> where SP::Target: SignerProvider {
 
                // Now that we're past error-generating stuff, update our local state:
 
-               self.context.channel_state = ChannelState::FundingCreated as u32;
+               self.context.channel_state = ChannelState::FundingCreated;
                self.context.channel_id = funding_txo.to_channel_id();
 
                // If the funding transaction is a coinbase transaction, we need to set the minimum depth to 100.
@@ -6290,7 +6529,14 @@ impl<SP: Deref> OutboundV1Channel<SP> where SP::Target: SignerProvider {
        where
                F::Target: FeeEstimator
        {
-               if !self.context.is_outbound() || self.context.channel_state != ChannelState::OurInitSent as u32 { return Err(()); }
+               if !self.context.is_outbound() ||
+                       !matches!(
+                               self.context.channel_state, ChannelState::NegotiatingFunding(flags)
+                               if flags == NegotiatingFundingFlags::OUR_INIT_SENT
+                       )
+               {
+                       return Err(());
+               }
                if self.context.channel_type == ChannelTypeFeatures::only_static_remote_key() {
                        // We've exhausted our options
                        return Err(());
@@ -6321,7 +6567,7 @@ impl<SP: Deref> OutboundV1Channel<SP> where SP::Target: SignerProvider {
                if !self.context.is_outbound() {
                        panic!("Tried to open a channel for an inbound channel?");
                }
-               if self.context.channel_state != ChannelState::OurInitSent as u32 {
+               if self.context.have_received_message() {
                        panic!("Cannot generate an open_channel after we've moved forward");
                }
 
@@ -6367,7 +6613,7 @@ impl<SP: Deref> OutboundV1Channel<SP> where SP::Target: SignerProvider {
                if !self.context.is_outbound() {
                        return Err(ChannelError::Close("Got an accept_channel message from an inbound peer".to_owned()));
                }
-               if self.context.channel_state != ChannelState::OurInitSent as u32 {
+               if !matches!(self.context.channel_state, ChannelState::NegotiatingFunding(flags) if flags == NegotiatingFundingFlags::OUR_INIT_SENT) {
                        return Err(ChannelError::Close("Got an accept_channel message at a strange time".to_owned()));
                }
                if msg.dust_limit_satoshis > 21000000 * 100000000 {
@@ -6484,7 +6730,9 @@ impl<SP: Deref> OutboundV1Channel<SP> where SP::Target: SignerProvider {
                self.context.counterparty_cur_commitment_point = Some(msg.first_per_commitment_point);
                self.context.counterparty_shutdown_scriptpubkey = counterparty_shutdown_scriptpubkey;
 
-               self.context.channel_state = ChannelState::OurInitSent as u32 | ChannelState::TheirInitSent as u32;
+               self.context.channel_state = ChannelState::NegotiatingFunding(
+                       NegotiatingFundingFlags::OUR_INIT_SENT | NegotiatingFundingFlags::THEIR_INIT_SENT
+               );
                self.context.inbound_handshake_limits_override = None; // We're done enforcing limits on our peer's handshake now.
 
                Ok(())
@@ -6721,7 +6969,9 @@ impl<SP: Deref> InboundV1Channel<SP> where SP::Target: SignerProvider {
 
                                temporary_channel_id: Some(msg.temporary_channel_id),
                                channel_id: msg.temporary_channel_id,
-                               channel_state: (ChannelState::OurInitSent as u32) | (ChannelState::TheirInitSent as u32),
+                               channel_state: ChannelState::NegotiatingFunding(
+                                       NegotiatingFundingFlags::OUR_INIT_SENT | NegotiatingFundingFlags::THEIR_INIT_SENT
+                               ),
                                announcement_sigs_state: AnnouncementSigsState::NotSent,
                                secp_ctx,
 
@@ -6851,7 +7101,10 @@ impl<SP: Deref> InboundV1Channel<SP> where SP::Target: SignerProvider {
                if self.context.is_outbound() {
                        panic!("Tried to send accept_channel for an outbound channel?");
                }
-               if self.context.channel_state != (ChannelState::OurInitSent as u32) | (ChannelState::TheirInitSent as u32) {
+               if !matches!(
+                       self.context.channel_state, ChannelState::NegotiatingFunding(flags)
+                       if flags == (NegotiatingFundingFlags::OUR_INIT_SENT | NegotiatingFundingFlags::THEIR_INIT_SENT)
+               ) {
                        panic!("Tried to send accept_channel after channel had moved forward");
                }
                if self.context.cur_holder_commitment_transaction_number != INITIAL_COMMITMENT_NUMBER {
@@ -6931,7 +7184,10 @@ impl<SP: Deref> InboundV1Channel<SP> where SP::Target: SignerProvider {
                if self.context.is_outbound() {
                        return Err((self, ChannelError::Close("Received funding_created for an outbound channel?".to_owned())));
                }
-               if self.context.channel_state != (ChannelState::OurInitSent as u32 | ChannelState::TheirInitSent as u32) {
+               if !matches!(
+                       self.context.channel_state, ChannelState::NegotiatingFunding(flags)
+                       if flags == (NegotiatingFundingFlags::OUR_INIT_SENT | NegotiatingFundingFlags::THEIR_INIT_SENT)
+               ) {
                        // BOLT 2 says that if we disconnect before we send funding_signed we SHOULD NOT
                        // remember the channel, so it's safe to just send an error_message here and drop the
                        // channel.
@@ -6976,7 +7232,7 @@ impl<SP: Deref> InboundV1Channel<SP> where SP::Target: SignerProvider {
 
                // Now that we're past error-generating stuff, update our local state:
 
-               self.context.channel_state = ChannelState::FundingSent as u32;
+               self.context.channel_state = ChannelState::FundingSent(FundingSentFlags::new());
                self.context.channel_id = funding_txo.to_channel_id();
                self.context.cur_counterparty_commitment_transaction_number -= 1;
                self.context.cur_holder_commitment_transaction_number -= 1;
@@ -7095,7 +7351,13 @@ impl<SP: Deref> Writeable for Channel<SP> where SP::Target: SignerProvider {
                writer.write_all(&[0; 8])?;
 
                self.context.channel_id.write(writer)?;
-               (self.context.channel_state | ChannelState::PeerDisconnected as u32).write(writer)?;
+               {
+                       let mut channel_state = self.context.channel_state;
+                       if matches!(channel_state, ChannelState::FundingSent(_)|ChannelState::ChannelReady(_)) {
+                               channel_state.set_peer_disconnected();
+                       }
+                       channel_state.to_u32().write(writer)?;
+               }
                self.context.channel_value_satoshis.write(writer)?;
 
                self.context.latest_monitor_update_id.write(writer)?;
@@ -7428,7 +7690,7 @@ impl<'a, 'b, 'c, ES: Deref, SP: Deref> ReadableArgs<(&'a ES, &'b SP, u32, &'c Ch
                }
 
                let channel_id = Readable::read(reader)?;
-               let channel_state = Readable::read(reader)?;
+               let channel_state = ChannelState::from_u32(Readable::read(reader)?).map_err(|_| DecodeError::InvalidValue)?;
                let channel_value_satoshis = Readable::read(reader)?;
 
                let latest_monitor_update_id = Readable::read(reader)?;
@@ -7718,8 +7980,7 @@ impl<'a, 'b, 'c, ES: Deref, SP: Deref> ReadableArgs<(&'a ES, &'b SP, u32, &'c Ch
                        let mut holder_signer = signer_provider.derive_channel_signer(channel_value_satoshis, channel_keys_id);
                        // If we've gotten to the funding stage of the channel, populate the signer with its
                        // required channel parameters.
-                       let non_shutdown_state = channel_state & (!MULTI_STATE_FLAGS);
-                       if non_shutdown_state & !STATE_FLAGS >= (ChannelState::FundingCreated as u32) {
+                       if channel_state >= ChannelState::FundingCreated {
                                holder_signer.provide_channel_parameters(&channel_parameters);
                        }
                        (channel_keys_id, holder_signer)
@@ -7945,7 +8206,7 @@ mod tests {
        use crate::ln::channel_keys::{RevocationKey, RevocationBasepoint};
        use crate::ln::channelmanager::{self, HTLCSource, PaymentId};
        use crate::ln::channel::InitFeatures;
-       use crate::ln::channel::{Channel, ChannelState, InboundHTLCOutput, OutboundV1Channel, InboundV1Channel, OutboundHTLCOutput, InboundHTLCState, OutboundHTLCState, HTLCCandidate, HTLCInitiator, HTLCUpdateAwaitingACK, commit_tx_fee_msat};
+       use crate::ln::channel::{FundingSentFlags, Channel, ChannelState, InboundHTLCOutput, OutboundV1Channel, InboundV1Channel, OutboundHTLCOutput, InboundHTLCState, OutboundHTLCState, HTLCCandidate, HTLCInitiator, HTLCUpdateAwaitingACK, commit_tx_fee_msat};
        use crate::ln::channel::{MAX_FUNDING_SATOSHIS_NO_WUMBO, TOTAL_BITCOIN_SUPPLY_SATOSHIS, MIN_THEIR_CHAN_RESERVE_SATOSHIS};
        use crate::ln::features::{ChannelFeatures, ChannelTypeFeatures, NodeFeatures};
        use crate::ln::msgs;
@@ -9637,11 +9898,7 @@ mod tests {
                // as the funding transaction depends on all channels in the batch becoming ready.
                assert!(node_a_updates.channel_ready.is_none());
                assert!(node_a_updates.funding_broadcastable.is_none());
-               assert_eq!(
-                       node_a_chan.context.channel_state,
-                       ChannelState::FundingSent as u32 |
-                       ChannelState::WaitingForBatch as u32,
-               );
+               assert_eq!(node_a_chan.context.channel_state, ChannelState::FundingSent(FundingSentFlags::WAITING_FOR_BATCH));
 
                // It is possible to receive a 0conf channel_ready from the remote node.
                node_a_chan.channel_ready(
@@ -9654,18 +9911,12 @@ mod tests {
                ).unwrap();
                assert_eq!(
                        node_a_chan.context.channel_state,
-                       ChannelState::FundingSent as u32 |
-                       ChannelState::WaitingForBatch as u32 |
-                       ChannelState::TheirChannelReady as u32,
+                       ChannelState::FundingSent(FundingSentFlags::WAITING_FOR_BATCH | FundingSentFlags::THEIR_CHANNEL_READY)
                );
 
                // Clear the ChannelState::WaitingForBatch only when called by ChannelManager.
                node_a_chan.set_batch_ready();
-               assert_eq!(
-                       node_a_chan.context.channel_state,
-                       ChannelState::FundingSent as u32 |
-                       ChannelState::TheirChannelReady as u32,
-               );
+               assert_eq!(node_a_chan.context.channel_state, ChannelState::FundingSent(FundingSentFlags::THEIR_CHANNEL_READY));
                assert!(node_a_chan.check_get_channel_ready(0).is_some());
        }
 }