Account for coinbase tx in ChannelContext::minimum_depth

Now that FundedScope::minimum_depth_override is used to override the
minimum depth with COINBASE_MATURITY when the funding transaction is the
coinbase transaction, use this in ChannelContext::minimum_depth method.
Also, add a minimum_depth to Channel. The one on ChannelContext can
become private once FudningScope doesn't need to be accessed directly
from a ChannelManager macro.

This fixes ChannelDetails showing an incorrect minimum depth when the
coinbase transaction is used to fund the channel.

Author: jkczyz

lightning/src/ln/channel.rs

@@ -1829,6 +1829,10 @@ where
 			ChannelPhase::UnfundedV2(chan) => chan.context.get_available_balances_for_scope(&chan.funding, fee_estimator),
 		}
 	}
+
+	pub fn minimum_depth(&self) -> Option<u32> {
+		self.context().minimum_depth(self.funding())
+	}
 }
 
 impl<SP: Deref> From<OutboundV1Channel<SP>> for Channel<SP>
@@ -3675,8 +3679,8 @@ where
 		self.temporary_channel_id
 	}
 
-	pub fn minimum_depth(&self) -> Option<u32> {
-		self.minimum_depth
+	pub(super) fn minimum_depth(&self, funding: &FundingScope) -> Option<u32> {
+		funding.minimum_depth_override.or(self.minimum_depth)
 	}
 
 	/// Gets the "user_id" value passed into the construction of this channel. It has no special
@@ -8977,9 +8981,9 @@ where
 	}
 
 	fn check_funding_meets_minimum_depth(&self, funding: &FundingScope, height: u32) -> bool {
-		let minimum_depth = funding
-			.minimum_depth_override
-			.or(self.context.minimum_depth)
+		let minimum_depth = self
+			.context
+			.minimum_depth(funding)
 			.expect("ChannelContext::minimum_depth should be set for FundedChannel");
 
 		// Zero-conf channels always meet the minimum depth.

lightning/src/ln/channel_state.rs

@@ -531,7 +531,7 @@ impl ChannelDetails {
 			next_outbound_htlc_limit_msat: balance.next_outbound_htlc_limit_msat,
 			next_outbound_htlc_minimum_msat: balance.next_outbound_htlc_minimum_msat,
 			user_channel_id: context.get_user_id(),
-			confirmations_required: context.minimum_depth(),
+			confirmations_required: channel.minimum_depth(),
 			confirmations: Some(funding.get_funding_tx_confirmations(best_block_height)),
 			force_close_spend_delay: funding.get_counterparty_selected_contest_delay(),
 			is_outbound: funding.is_outbound(),

lightning/src/ln/channelmanager.rs

@@ -3163,7 +3163,7 @@ macro_rules! locked_close_channel {
 		// into the map (which prevents the `PeerState` from being cleaned up) for channels that
 		// never even got confirmations (which would open us up to DoS attacks).
 		let update_id = $channel_context.get_latest_monitor_update_id();
-		if $channel_funding.get_funding_tx_confirmation_height().is_some() || $channel_context.minimum_depth() == Some(0) || update_id > 1 {
+		if $channel_funding.get_funding_tx_confirmation_height().is_some() || $channel_context.minimum_depth($channel_funding) == Some(0) || update_id > 1 {
 			let chan_id = $channel_context.channel_id();
 			$peer_state.closed_channel_monitor_update_ids.insert(chan_id, update_id);
 		}
@@ -8291,7 +8291,7 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
 
 		if accept_0conf {
 			// This should have been correctly configured by the call to Inbound(V1/V2)Channel::new.
-			debug_assert!(channel.context().minimum_depth().unwrap() == 0);
+			debug_assert!(channel.minimum_depth().unwrap() == 0);
 		} else if channel.funding().get_channel_type().requires_zero_conf() {
 			let send_msg_err_event = MessageSendEvent::HandleError {
 				node_id: channel.context().get_counterparty_node_id(),
@@ -8369,7 +8369,7 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
 				Some(funded_chan) => {
 					// This covers non-zero-conf inbound `Channel`s that we are currently monitoring, but those
 					// which have not yet had any confirmations on-chain.
-					if !funded_chan.funding.is_outbound() && funded_chan.context.minimum_depth().unwrap_or(1) != 0 &&
+					if !funded_chan.funding.is_outbound() && chan.minimum_depth().unwrap_or(1) != 0 &&
 						funded_chan.funding.get_funding_tx_confirmations(best_block_height) == 0
 					{
 						num_unfunded_channels += 1;
@@ -8382,7 +8382,7 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
 					}
 
 					// 0conf channels are not considered unfunded.
-					if chan.context().minimum_depth().unwrap_or(1) == 0 {
+					if chan.minimum_depth().unwrap_or(1) == 0 {
 						continue;
 					}