Do not serialize `Channel::last_sent_closing_fee` to disk

We're supposed to write `Channel` to disk as if
`remove_uncommitted_htlcs_and_mark_paused` had just run, however we
were writing `last_sent_closing_fee` to disk (if it is not-None),
whereas `remove_uncommitted_htlcs_and_mark_paused` clears it.
Indeed, the BOLTs say fee "... negotiation restarts on
reconnection."

diff --git a/lightning/src/ln/channel.rs b/lightning/src/ln/channel.rs
index e41d6d287b914d060149d047408ca5b7c1e2b191..d47b4e72439f401334d5f500b77c2338408349b0 100644 (file)
--- a/lightning/src/ln/channel.rs
+++ b/lightning/src/ln/channel.rs
@@ -4973,15 +4973,11 @@ impl<Signer: Sign> Writeable for Channel<Signer> {
                self.update_time_counter.write(writer)?;
                self.feerate_per_kw.write(writer)?;
 
-               match self.last_sent_closing_fee {
-                       Some((feerate, fee, sig)) => {
-                               1u8.write(writer)?;
-                               feerate.write(writer)?;
-                               fee.write(writer)?;
-                               sig.write(writer)?;
-                       },
-                       None => 0u8.write(writer)?,
-               }
+               // Versions prior to 0.0.100 expected to read the fields of `last_sent_closing_fee` here,
+               // however we are supposed to restart shutdown fee negotiation on reconnect (and wipe
+               // `last_send_closing_fee` in `remove_uncommitted_htlcs_and_mark_paused`) so we should never
+               // consider the stale state on reload.
+               0u8.write(writer)?;
 
                self.funding_tx_confirmed_in.write(writer)?;
                self.funding_tx_confirmation_height.write(writer)?;
@@ -5189,11 +5185,19 @@ impl<'a, Signer: Sign, K: Deref> ReadableArgs<&'a K> for Channel<Signer>
                let update_time_counter = Readable::read(reader)?;
                let feerate_per_kw = Readable::read(reader)?;
 
-               let last_sent_closing_fee = match <u8 as Readable>::read(reader)? {
-                       0 => None,
-                       1 => Some((Readable::read(reader)?, Readable::read(reader)?, Readable::read(reader)?)),
+               // Versions prior to 0.0.100 expected to read the fields of `last_sent_closing_fee` here,
+               // however we are supposed to restart shutdown fee negotiation on reconnect (and wipe
+               // `last_send_closing_fee` in `remove_uncommitted_htlcs_and_mark_paused`) so we should never
+               // consider the stale state on reload.
+               match <u8 as Readable>::read(reader)? {
+                       0 => {},
+                       1 => {
+                               let _: u32 = Readable::read(reader)?;
+                               let _: u64 = Readable::read(reader)?;
+                               let _: Signature = Readable::read(reader)?;
+                       },
                        _ => return Err(DecodeError::InvalidValue),
-               };
+               }
 
                let funding_tx_confirmed_in = Readable::read(reader)?;
                let funding_tx_confirmation_height = Readable::read(reader)?;
@@ -5321,7 +5325,7 @@ impl<'a, Signer: Sign, K: Deref> ReadableArgs<&'a K> for Channel<Signer>
                        #[cfg(debug_assertions)]
                        counterparty_max_commitment_tx_output: Mutex::new((0, 0)),
 
-                       last_sent_closing_fee,
+                       last_sent_closing_fee: None,
 
                        funding_tx_confirmed_in,
                        funding_tx_confirmation_height,