Don't pass a latest-block-time to Channel unless we have one

When calling `Channel::best_block_updated` we pass it the timestamp
of the block we're connecting so that it can track the highest
timestamp it has seen.

However, in some cases, we don't actually have a timestamp to pass,
which `Channel::best_block_updated` will happily ignore as it
always takes the `max` of its existing value. Thus, we really
should pass a `None` to ensure the API is understandable, which we
do here.

Author: TheBlueMatt

lightning/src/ln/channel.rs

@@ -10077,8 +10077,8 @@ where
 	/// May return some HTLCs (and their payment_hash) which have timed out and should be failed
 	/// back.
 	pub fn best_block_updated<NS: Deref, L: Deref>(
-		&mut self, height: u32, highest_header_time: u32, chain_hash: ChainHash, node_signer: &NS,
-		user_config: &UserConfig, logger: &L,
+		&mut self, height: u32, highest_header_time: Option<u32>, chain_hash: ChainHash,
+		node_signer: &NS, user_config: &UserConfig, logger: &L,
 	) -> Result<BestBlockUpdatedRes, ClosureReason>
 	where
 		NS::Target: NodeSigner,
@@ -10094,7 +10094,7 @@ where
 
 	#[rustfmt::skip]
 	fn do_best_block_updated<NS: Deref, L: Deref>(
-		&mut self, height: u32, highest_header_time: u32,
+		&mut self, height: u32, highest_header_time: Option<u32>,
 		chain_node_signer: Option<(ChainHash, &NS, &UserConfig)>, logger: &L
 	) -> Result<(Option<FundingConfirmedMessage>, Vec<(HTLCSource, PaymentHash)>, Option<msgs::AnnouncementSignatures>), ClosureReason>
 	where
@@ -10118,7 +10118,9 @@ where
 			}
 		});
 
-		self.context.update_time_counter = cmp::max(self.context.update_time_counter, highest_header_time);
+		if let Some(time) = highest_header_time {
+			self.context.update_time_counter = cmp::max(self.context.update_time_counter, time);
+		}
 
 		// Check if the funding transaction was unconfirmed
 		let funding_tx_confirmations = self.funding.get_funding_tx_confirmations(height);
@@ -10273,12 +10275,9 @@ where
 				// We handle the funding disconnection by calling best_block_updated with a height one
 				// below where our funding was connected, implying a reorg back to conf_height - 1.
 				let reorg_height = funding.funding_tx_confirmation_height - 1;
-				// We use the time field to bump the current time we set on channel updates if its
-				// larger. If we don't know that time has moved forward, we can just set it to the last
-				// time we saw and it will be ignored.
-				let best_time = self.context.update_time_counter;
 
-				match self.do_best_block_updated(reorg_height, best_time, None::<(ChainHash, &&dyn NodeSigner, &UserConfig)>, logger) {
+				let signer_config = None::<(ChainHash, &&dyn NodeSigner, &UserConfig)>;
+				match self.do_best_block_updated(reorg_height, None, signer_config, logger) {
 					Ok((channel_ready, timed_out_htlcs, announcement_sigs)) => {
 						assert!(channel_ready.is_none(), "We can't generate a funding with 0 confirmations?");
 						assert!(timed_out_htlcs.is_empty(), "We can't have accepted HTLCs with a timeout before our funding confirmation?");

lightning/src/ln/channelmanager.rs

@@ -13236,7 +13236,7 @@ where
 		self.do_chain_event(Some(fork_point.height), |channel| {
 			channel.best_block_updated(
 				fork_point.height,
-				0,
+				None,
 				self.chain_hash,
 				&self.node_signer,
 				&self.default_configuration,
@@ -13286,7 +13286,17 @@ where
 		let last_best_block_height = self.best_block.read().unwrap().height;
 		if height < last_best_block_height {
 			let timestamp = self.highest_seen_timestamp.load(Ordering::Acquire);
-			self.do_chain_event(Some(last_best_block_height), |channel| channel.best_block_updated(last_best_block_height, timestamp as u32, self.chain_hash, &self.node_signer, &self.default_configuration, &&WithChannelContext::from(&self.logger, &channel.context, None)));
+			let do_update = |channel: &mut FundedChannel<SP>| {
+				channel.best_block_updated(
+					last_best_block_height,
+					Some(timestamp as u32),
+					self.chain_hash,
+					&self.node_signer,
+					&self.default_configuration,
+					&&WithChannelContext::from(&self.logger, &channel.context, None)
+				)
+			};
+			self.do_chain_event(Some(last_best_block_height), do_update);
 		}
 	}
 
@@ -13346,7 +13356,14 @@ where
 				}
 			}
 
-			channel.best_block_updated(height, header.time, self.chain_hash, &self.node_signer, &self.default_configuration, &&WithChannelContext::from(&self.logger, &channel.context, None))
+			channel.best_block_updated(
+				height,
+				Some(header.time),
+				self.chain_hash,
+				&self.node_signer,
+				&self.default_configuration,
+				&&WithChannelContext::from(&self.logger, &channel.context, None)
+			)
 		});
 
 		macro_rules! max_time {