Move channel_ready check after processing transactions

In preparation for checking for confirmed splice funding transactions,
move the channel_ready check to after processing all newly confirmed
transactions. This will allow differentiating between the initial
funding transaction from a splice funding transaction. The former
results in channel_ready while the latter results in a splice_locked.

Note that doing this outside the processing loop is necessary because
check_get_channel_ready and get_announcement_sigs take &mut self, which
isn't possible when iterating over all funding scopes. Moving the checks
after processing means any mutations occurring in those methods will not
happen if an Err is returned in the processing loop. This should be fine
since it would result in a channel closure.

Author: jkczyz

lightning/src/ln/channel.rs

@@ -8161,7 +8161,11 @@ impl<SP: Deref> FundedChannel<SP> where
 		NS::Target: NodeSigner,
 		L::Target: Logger
 	{
-		let mut msgs = (None, None);
+		struct ConfirmedFunding<'a> {
+			funding_tx: &'a Transaction,
+		}
+
+		let mut confirmed_funding = None;
 		if let Some(funding_txo) = self.funding.get_funding_txo() {
 			for &(index_in_block, tx) in txdata.iter() {
 				// Check if the transaction is the expected funding transaction, and if it is,
@@ -8196,28 +8200,16 @@ impl<SP: Deref> FundedChannel<SP> where
 									}
 								}
 							}
+
 							self.context.funding_tx_confirmation_height = height;
 							self.context.funding_tx_confirmed_in = Some(*block_hash);
 							self.context.short_channel_id = match scid_from_parts(height as u64, index_in_block as u64, txo_idx as u64) {
 								Ok(scid) => Some(scid),
 								Err(_) => panic!("Block was bogus - either height was > 16 million, had > 16 million transactions, or had > 65k outputs"),
-							}
+							};
 						}
-						// If this is a coinbase transaction and not a 0-conf channel
-						// we should update our min_depth to 100 to handle coinbase maturity
-						if tx.is_coinbase() &&
-							self.context.minimum_depth.unwrap_or(0) > 0 &&
-							self.context.minimum_depth.unwrap_or(0) < COINBASE_MATURITY {
-							self.context.minimum_depth = Some(COINBASE_MATURITY);
-						}
-					}
-					// If we allow 1-conf funding, we may need to check for channel_ready here and
-					// send it immediately instead of waiting for a best_block_updated call (which
-					// may have already happened for this block).
-					if let Some(channel_ready) = self.check_get_channel_ready(height, logger) {
-						log_info!(logger, "Sending a channel_ready to our peer for channel {}", &self.context.channel_id);
-						let announcement_sigs = self.get_announcement_sigs(node_signer, chain_hash, user_config, height, logger);
-						msgs = (Some(channel_ready), announcement_sigs);
+
+						confirmed_funding = Some(ConfirmedFunding { funding_tx: &tx });
 					}
 				}
 				for inp in tx.input.iter() {
@@ -8228,7 +8220,27 @@ impl<SP: Deref> FundedChannel<SP> where
 				}
 			}
 		}
-		Ok(msgs)
+
+		if let Some(ConfirmedFunding { funding_tx }) = confirmed_funding {
+			// If this is a coinbase transaction and not a 0-conf channel
+			// we should update our min_depth to 100 to handle coinbase maturity
+			if funding_tx.is_coinbase() &&
+				self.context.minimum_depth.unwrap_or(0) > 0 &&
+				self.context.minimum_depth.unwrap_or(0) < COINBASE_MATURITY {
+				self.context.minimum_depth = Some(COINBASE_MATURITY);
+			}
+
+			// If we allow 1-conf funding, we may need to check for channel_ready here and
+			// send it immediately instead of waiting for a best_block_updated call (which
+			// may have already happened for this block).
+			if let Some(channel_ready) = self.check_get_channel_ready(height, logger) {
+				log_info!(logger, "Sending a channel_ready to our peer for channel {}", &self.context.channel_id);
+				let announcement_sigs = self.get_announcement_sigs(node_signer, chain_hash, user_config, height, logger);
+				return Ok((Some(channel_ready), announcement_sigs));
+			}
+		}
+
+		Ok((None, None))
 	}
 
 	/// When a new block is connected, we check the height of the block against outbound holding