Add APIError::IncompatibleShutdownScript

Author: jkczyz

fuzz/src/chanmon_consistency.rs

@@ -253,6 +253,7 @@ fn check_api_err(api_err: APIError) {
 		APIError::MonitorUpdateFailed => {
 			// We can (obviously) temp-fail a monitor update
 		},
+		APIError::IncompatibleShutdownScript { .. } => panic!("Cannot send an incompatible shutdown script"),
 	}
 }
 #[inline]

lightning/src/ln/channel.rs

@@ -607,8 +607,8 @@ impl<Signer: Sign> Channel<Signer> {
 		} else { None };
 
 		if let Some(shutdown_scriptpubkey) = &shutdown_scriptpubkey {
-			if !shutdown_scriptpubkey.is_compatible(their_features) {
-				return Err(APIError::APIMisuseError { err: format!("Provided a scriptpubkey format not accepted by peer: {}", shutdown_scriptpubkey) });
+			if !shutdown_scriptpubkey.is_compatible(&their_features) {
+				return Err(APIError::IncompatibleShutdownScript { script: shutdown_scriptpubkey.clone() });
 			}
 		}
 
@@ -4487,7 +4487,7 @@ impl<Signer: Sign> Channel<Signer> {
 			None => {
 				let shutdown_scriptpubkey = keys_provider.get_shutdown_scriptpubkey();
 				if !shutdown_scriptpubkey.is_compatible(their_features) {
-					return Err(APIError::APIMisuseError { err: format!("Provided a scriptpubkey format not accepted by peer: {}", shutdown_scriptpubkey) });
+					return Err(APIError::IncompatibleShutdownScript { script: shutdown_scriptpubkey.clone() });
 				}
 				self.shutdown_scriptpubkey = Some(shutdown_scriptpubkey);
 				true
@@ -5253,15 +5253,17 @@ mod tests {
 		let seed = [42; 32];
 		let network = Network::Testnet;
 		let keys_provider = test_utils::TestKeysInterface::new(&seed, network);
-		keys_provider.expect(OnGetShutdownScriptpubkey { returns: non_v0_segwit_shutdown_script });
+		keys_provider.expect(OnGetShutdownScriptpubkey {
+			returns: non_v0_segwit_shutdown_script.clone(),
+		});
 
 		let fee_estimator = TestFeeEstimator { fee_est: 253 };
 		let secp_ctx = Secp256k1::new();
 		let node_id = PublicKey::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[42; 32]).unwrap());
 		let config = UserConfig::default();
 		match Channel::<EnforcingSigner>::new_outbound(&&fee_estimator, &&keys_provider, node_id, &features, 10000000, 100000, 42, &config) {
-			Err(APIError::APIMisuseError { err }) => {
-				assert_eq!(err, "Provided a scriptpubkey format not accepted by peer. script: (60020028)");
+			Err(APIError::IncompatibleShutdownScript { script }) => {
+				assert_eq!(script.into_inner(), non_v0_segwit_shutdown_script.into_inner());
 			},
 			Err(e) => panic!("Unexpected error: {:?}", e),
 			Ok(_) => panic!("Expected error"),

lightning/src/ln/functional_tests.rs

@@ -7693,7 +7693,9 @@ fn test_unsupported_anysegwit_shutdown_script() {
 
 	let chan = create_announced_chan_between_nodes(&nodes, 0, 1, node_cfgs[0].features.clone(), node_cfgs[1].features.clone());
 	match nodes[1].node.close_channel(&OutPoint { txid: chan.3.txid(), index: 0 }.to_channel_id()) {
-		Err(APIError::APIMisuseError { err }) => assert_eq!(err, "Provided a scriptpubkey format not accepted by peer. script: (60020028)"),
+		Err(APIError::IncompatibleShutdownScript { script }) => {
+			assert_eq!(script.into_inner(), unsupported_shutdown_script.clone().into_inner());
+		},
 		Err(e) => panic!("Unexpected error: {:?}", e),
 		Ok(_) => panic!("Expected error"),
 	}

lightning/src/util/errors.rs

@@ -9,6 +9,8 @@
 
 //! Error types live here.
 
+use ln::script::ShutdownScript;
+
 use alloc::string::String;
 use core::fmt;
 
@@ -47,6 +49,18 @@ pub enum APIError {
 	/// An attempt to call watch/update_channel returned an Err (ie you did this!), causing the
 	/// attempted action to fail.
 	MonitorUpdateFailed,
+	/// [`KeysInterface::get_shutdown_scriptpubkey`] returned a shutdown scriptpubkey incompatible
+	/// with the channel counterparty as negotiated in [`InitFeatures`].
+	///
+	/// Using a SegWit v0 script should resolve this issue. If you cannot, you won't be able to open
+	/// a channel or cooperatively close one with this peer (and will have to force-close instead).
+	///
+	/// [`KeysInterface::get_shutdown_scriptpubkey`]: crate::chain::keysinterface::KeysInterface::get_shutdown_scriptpubkey
+	/// [`InitFeatures`]: crate::ln::features::InitFeatures
+	IncompatibleShutdownScript {
+		/// The incompatible shutdown script.
+		script: ShutdownScript,
+	},
 }
 
 impl fmt::Debug for APIError {
@@ -57,6 +71,9 @@ impl fmt::Debug for APIError {
 			APIError::RouteError {ref err} => f.write_str(err),
 			APIError::ChannelUnavailable {ref err} => f.write_str(err),
 			APIError::MonitorUpdateFailed => f.write_str("Client indicated a channel monitor update failed"),
+			APIError::IncompatibleShutdownScript { ref script } => {
+				write!(f, "Provided a scriptpubkey format not accepted by peer: {}", script)
+			},
 		}
 	}
 }