Add waiting_tlc_ack for HTLC operations

src/fiber/channel.rs

@@ -1083,7 +1083,11 @@ where
                 state.update_state(ChannelState::SigningCommitment(flags));
                 state.maybe_transition_to_tx_signatures(flags, &self.network)?;
             }
-            CommitmentSignedFlags::ChannelReady() => {}
+            CommitmentSignedFlags::ChannelReady() => {
+                // we are in ChannelReady state for TLC operations, after sending commitment_signed message,
+                // set the flag of waiting_tlc_ack to true, so that we don't handle TLC operations until we receive the ack.
+                state.waiting_tlc_ack = true;
+            }
             CommitmentSignedFlags::PendingShutdown(_) => {
                 state.maybe_transition_to_shutdown(&self.network)?;
             }
@@ -1097,6 +1101,7 @@ where
         command: AddTlcCommand,
     ) -> Result<u64, ProcessingChannelError> {
         debug!("handle add tlc command : {:?}", &command);
+        state.check_ack_status_for_tlc()?;
         state.check_for_tlc_update(Some(command.amount))?;
         state.check_tlc_expiry(command.expiry)?;
         let tlc = state.create_outbounding_tlc(command);
@@ -1138,6 +1143,7 @@ where
         state: &mut ChannelActorState,
         command: RemoveTlcCommand,
     ) -> ProcessingChannelResult {
+        state.check_ack_status_for_tlc()?;
         state.check_for_tlc_update(None)?;
         let tlc = state.remove_tlc_with_reason(TLCId::Received(command.id), &command.reason)?;
         let msg = FiberMessageWithPeerId::new(
@@ -2002,6 +2008,10 @@ pub struct ChannelActorState {
     // An inbound channel is one where the counterparty is the funder of the channel.
     pub is_acceptor: bool,
 
+    // we are expecting ACK for the commitment_signed message,
+    // when we are in this state, we won't process any AddTlc and RemoveTlc commands.
+    pub waiting_tlc_ack: bool,
+
     // TODO: consider transaction fee while building the commitment transaction.
 
     // The invariant here is that the sum of `to_local_amount` and `to_remote_amount`
@@ -2173,6 +2183,8 @@ pub enum ProcessingChannelError {
     RepeatedProcessing(String),
     #[error("Invalid parameter: {0}")]
     InvalidParameter(String),
+    #[error("Unable to handle TLC command in waiting TLC ACK state")]
+    WaitingTlcAck,
     #[error("Capacity error: {0}")]
     CapacityError(#[from] CapacityError),
     #[error("Failed to spawn actor: {0}")]
@@ -2777,6 +2789,7 @@ impl ChannelActorState {
             funding_tx: None,
             funding_tx_confirmed_at: None,
             is_acceptor: true,
+            waiting_tlc_ack: false,
             funding_udt_type_script,
             to_local_amount: local_value,
             to_remote_amount: remote_value,
@@ -2840,6 +2853,7 @@ impl ChannelActorState {
             funding_tx_confirmed_at: None,
             funding_udt_type_script,
             is_acceptor: false,
+            waiting_tlc_ack: false,
             to_local_amount,
             to_remote_amount: 0,
             commitment_fee_rate,
@@ -4119,6 +4133,12 @@ impl ChannelActorState {
         Ok(())
     }
 
+    fn check_ack_status_for_tlc(&self) -> ProcessingChannelResult {
+        if self.waiting_tlc_ack {
+            return Err(ProcessingChannelError::WaitingTlcAck);
+        }
+        Ok(())
+    }
     fn check_for_tlc_update(&self, add_tlc_amount: Option<u128>) -> ProcessingChannelResult {
         match self.state {
             ChannelState::ChannelReady() => {}
@@ -4915,6 +4935,7 @@ impl ChannelActorState {
 
         self.update_state_on_raa_msg(true);
         self.append_remote_commitment_point(next_per_commitment_point);
+        self.waiting_tlc_ack = false;
 
         emit_service_event(
             network,