Support option_upfront_shutdown_script for local peer

Track shutdown_pubkey of peer at open/accept_channel messages

Fix encoding_init test

Author: Antoine Riard

src/ln/channel.rs

@@ -522,7 +522,7 @@ impl Channel {
 
 	/// Creates a new channel from a remote sides' request for one.
 	/// Assumes chain_hash has already been checked and corresponds with what we expect!
-	pub fn new_from_req(fee_estimator: &FeeEstimator, keys_provider: &Arc<KeysInterface>, their_node_id: PublicKey, _their_local_features: LocalFeatures, msg: &msgs::OpenChannel, user_id: u64, logger: Arc<Logger>, config: &UserConfig) -> Result<Channel, ChannelError> {
+	pub fn new_from_req(fee_estimator: &FeeEstimator, keys_provider: &Arc<KeysInterface>, their_node_id: PublicKey, their_local_features: LocalFeatures, msg: &msgs::OpenChannel, user_id: u64, logger: Arc<Logger>, config: &UserConfig) -> Result<Channel, ChannelError> {
 		let chan_keys = keys_provider.get_channel_keys(true);
 		let mut local_config = (*config).channel_options.clone();
 
@@ -625,6 +625,27 @@ impl Channel {
 		channel_monitor.set_their_base_keys(&msg.htlc_basepoint, &msg.delayed_payment_basepoint);
 		channel_monitor.set_their_to_self_delay(msg.to_self_delay);
 
+		let their_shutdown_scriptpubkey = if their_local_features.supports_upfront_shutdown_script() {
+			match &msg.shutdown_scriptpubkey {
+				&OptionalField::Present(ref script) => {
+					// Peer is signaling upfront_shutdown and has provided a non-accepted scriptpubkey format. We enforce it while receiving shutdown msg
+					if script.is_p2pkh() || script.is_p2sh() || script.is_v0_p2wsh() || script.is_v0_p2wpkh() {
+						Some(script.clone())
+					// Peer is signaling upfront_shutdown and has opt-out with a 0-length script. We don't enforce anything
+					} else if script.len() == 0 {
+						None
+					// Peer is signaling upfront_shutdown and has provided a non-accepted scriptpubkey format. Fail the channel
+					} else {
+						return Err(ChannelError::Close("Peer is signaling upfront_shutdown but has provided a non-accepted scriptpubkey format"));
+					}
+				},
+				// Peer is signaling upfront shutdown but don't opt-out with correct mechanism (a.k.a 0-length script). Peer looks buggy, we fail the channel
+				&OptionalField::Absent => {
+					return Err(ChannelError::Close("Peer is signaling upfront_shutdown but we don't get any script. Use 0-length script to opt-out"));
+				}
+			}
+		} else { None };
+
 		let mut chan = Channel {
 			user_id: user_id,
 			config: local_config,
@@ -692,7 +713,7 @@ impl Channel {
 			their_prev_commitment_point: None,
 			their_node_id: their_node_id,
 
-			their_shutdown_scriptpubkey: None,
+			their_shutdown_scriptpubkey,
 
 			channel_monitor: channel_monitor,
 
@@ -1341,7 +1362,7 @@ impl Channel {
 
 	// Message handlers:
 
-	pub fn accept_channel(&mut self, msg: &msgs::AcceptChannel, config: &UserConfig, _their_local_features: LocalFeatures) -> Result<(), ChannelError> {
+	pub fn accept_channel(&mut self, msg: &msgs::AcceptChannel, config: &UserConfig, their_local_features: LocalFeatures) -> Result<(), ChannelError> {
 		// Check sanity of message fields:
 		if !self.channel_outbound {
 			return Err(ChannelError::Close("Got an accept_channel message from an inbound peer"));
@@ -1400,6 +1421,27 @@ impl Channel {
 			return Err(ChannelError::Close("We consider the minimum depth to be unreasonably large"));
 		}
 
+		let their_shutdown_scriptpubkey = if their_local_features.supports_upfront_shutdown_script() {
+			match &msg.shutdown_scriptpubkey {
+				&OptionalField::Present(ref script) => {
+					// Peer is signaling upfront_shutdown and has provided a non-accepted scriptpubkey format. We enforce it while receiving shutdown msg
+					if script.is_p2pkh() || script.is_p2sh() || script.is_v0_p2wsh() || script.is_v0_p2wpkh() {
+						Some(script.clone())
+					// Peer is signaling upfront_shutdown and has opt-out with a 0-length script. We don't enforce anything
+					} else if script.len() == 0 {
+						None
+					// Peer is signaling upfront_shutdown and has provided a non-accepted scriptpubkey format. Fail the channel
+					} else {
+						return Err(ChannelError::Close("Peer is signaling upfront_shutdown but has provided a non-accepted scriptpubkey format"));
+					}
+				},
+				// Peer is signaling upfront shutdown but don't opt-out with correct mechanism (a.k.a 0-length script). Peer looks buggy, we fail the channel
+				&OptionalField::Absent => {
+					return Err(ChannelError::Close("Peer is signaling upfront_shutdown but we don't get any script. Use 0-length script to opt-out"));
+				}
+			}
+		} else { None };
+
 		self.channel_monitor.set_their_base_keys(&msg.htlc_basepoint, &msg.delayed_payment_basepoint);
 
 		self.their_dust_limit_satoshis = msg.dust_limit_satoshis;
@@ -1415,6 +1457,7 @@ impl Channel {
 		self.their_delayed_payment_basepoint = Some(msg.delayed_payment_basepoint);
 		self.their_htlc_basepoint = Some(msg.htlc_basepoint);
 		self.their_cur_commitment_point = Some(msg.first_per_commitment_point);
+		self.their_shutdown_scriptpubkey = their_shutdown_scriptpubkey;
 
 		let obscure_factor = self.get_commitment_transaction_number_obscure_factor();
 		self.channel_monitor.set_commitment_obscure_factor(obscure_factor);

src/ln/msgs.rs

@@ -60,9 +60,16 @@ pub struct LocalFeatures {
 
 impl LocalFeatures {
 	/// Create a blank LocalFeatures flags (visibility extended for fuzz tests)
+	#[cfg(not(feature = "fuzztarget"))]
+	pub(crate) fn new() -> LocalFeatures {
+		LocalFeatures {
+			flags: vec![1 << 4],
+		}
+	}
+	#[cfg(feature = "fuzztarget")]
 	pub fn new() -> LocalFeatures {
 		LocalFeatures {
-			flags: Vec::new(),
+			flags: vec![1 << 4],
 		}
 	}
 
@@ -87,8 +94,8 @@ impl LocalFeatures {
 	pub(crate) fn supports_upfront_shutdown_script(&self) -> bool {
 		self.flags.len() > 0 && (self.flags[0] & (3 << 4)) != 0
 	}
-	pub(crate) fn requires_upfront_shutdown_script(&self) -> bool {
-		self.flags.len() > 0 && (self.flags[0] & (1 << 4)) != 0
+	pub(crate) fn unset_upfront_shutdown_script(&mut self) {
+		self.flags[0] ^= 1 << 4;
 	}
 
 	pub(crate) fn requires_unknown_bits(&self) -> bool {
@@ -2011,9 +2018,9 @@ mod tests {
 			target_value.append(&mut hex::decode("0000").unwrap());
 		}
 		if initial_routing_sync {
-			target_value.append(&mut hex::decode("000108").unwrap());
+			target_value.append(&mut hex::decode("000118").unwrap());
 		} else {
-			target_value.append(&mut hex::decode("0000").unwrap());
+			target_value.append(&mut hex::decode("000110").unwrap());
 		}
 		assert_eq!(encoded_value, target_value);
 	}

src/ln/peer_handler.rs

@@ -587,10 +587,6 @@ impl<Descriptor: SocketDescriptor> PeerManager<Descriptor> {
 													log_info!(self, "Peer local features required data_loss_protect");
 													return Err(PeerHandleError{ no_connection_possible: true });
 												}
-												if msg.local_features.requires_upfront_shutdown_script() {
-													log_info!(self, "Peer local features required upfront_shutdown_script");
-													return Err(PeerHandleError{ no_connection_possible: true });
-												}
 												if peer.their_global_features.is_some() {
 													return Err(PeerHandleError{ no_connection_possible: false });
 												}