Handle if funding output is in a coinbase transaction

Author: benthecarman

lightning/src/ln/channel.rs

@@ -479,6 +479,9 @@ pub(crate) const MIN_AFFORDABLE_HTLC_COUNT: usize = 4;
 ///   * `EXPIRE_PREV_CONFIG_TICKS` = convergence_delay / tick_interval
 pub(crate) const EXPIRE_PREV_CONFIG_TICKS: usize = 5;
 
+/// Number of blocks needed for an output from a coinbase transaction to be spendable.
+pub(crate) const COINBASE_MATURITY: u32 = 100;
+
 // TODO: We should refactor this to be an Inbound/OutboundChannel until initial setup handshaking
 // has been completed, and then turn into a Channel to get compiler-time enforcement of things like
 // calling channel_id() before we're set up or things like get_outbound_funding_signed on an
@@ -5142,6 +5145,15 @@ impl<Signer: WriteableEcdsaChannelSigner> Channel<Signer> {
 							}
 						}
 					}
+
+					// 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_coin_base() &&
+						self.minimum_depth.unwrap_or(0) > 0 &&
+						self.minimum_depth.unwrap_or(0) < COINBASE_MATURITY {
+						self.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).
@@ -5454,6 +5466,15 @@ impl<Signer: WriteableEcdsaChannelSigner> Channel<Signer> {
 
 		self.channel_state = ChannelState::FundingCreated as u32;
 		self.channel_id = funding_txo.to_channel_id();
+
+		// If the funding transaction is a coinbase transaction, we need to set the minimum depth to 100
+		// We can skip this if it is a zero-conf channel.
+		if funding_transaction.is_coin_base() &&
+			self.minimum_depth.unwrap_or(0) > 0 &&
+			self.minimum_depth.unwrap_or(0) < COINBASE_MATURITY {
+			self.minimum_depth = Some(COINBASE_MATURITY);
+		}
+
 		self.funding_transaction = Some(funding_transaction);
 
 		Ok(msgs::FundingCreated {