Handle if funding output is in a coinbase transaction

Author: benthecarman

lightning/src/ln/channel.rs

@@ -478,6 +478,9 @@ 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.
+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
@@ -4964,6 +4967,14 @@ impl<Signer: WriteableEcdsaChannelSigner> Channel<Signer> {
 			self.funding_tx_confirmation_height = 0;
 		}
 
+        // If funding transaction is coinbase, we need to wait for 100 blocks before
+        // it is spendable. However, we can ignore this rule if the channel is 0-conf.
+		if self.funding_transaction.as_ref().map(|t| t.is_coin_base()).unwrap_or(false) &&
+			funding_tx_confirmations <= COINBASE_MATURITY as i64 &&
+			self.minimum_depth.unwrap_or(0) > 0 {
+			return None;
+		}
+
 		if funding_tx_confirmations < self.minimum_depth.unwrap_or(0) as i64 {
 			return None;
 		}
@@ -5375,6 +5386,14 @@ impl<Signer: WriteableEcdsaChannelSigner> Channel<Signer> {
 		self.channel_id = funding_txo.to_channel_id();
 		self.funding_transaction = Some(funding_transaction);
 
+        // 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);
+        }
+
 		Ok(msgs::FundingCreated {
 			temporary_channel_id,
 			funding_txid: funding_txo.txid,