Allow get_shutdown_scriptpubkey and get_destination_script to return an Error

fuzz/src/chanmon_consistency.rs

@@ -259,18 +259,18 @@ impl SignerProvider for KeyProvider {
 		})
 	}
 
-	fn get_destination_script(&self) -> Script {
+	fn get_destination_script(&self) -> Result<Script, ()> {
 		let secp_ctx = Secp256k1::signing_only();
 		let channel_monitor_claim_key = SecretKey::from_slice(&[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, self.node_secret[31]]).unwrap();
 		let our_channel_monitor_claim_key_hash = WPubkeyHash::hash(&PublicKey::from_secret_key(&secp_ctx, &channel_monitor_claim_key).serialize());
-		Builder::new().push_opcode(opcodes::all::OP_PUSHBYTES_0).push_slice(&our_channel_monitor_claim_key_hash[..]).into_script()
+		Ok(Builder::new().push_opcode(opcodes::all::OP_PUSHBYTES_0).push_slice(&our_channel_monitor_claim_key_hash[..]).into_script())
 	}
 
-	fn get_shutdown_scriptpubkey(&self) -> ShutdownScript {
+	fn get_shutdown_scriptpubkey(&self) -> Result<ShutdownScript, ()> {
 		let secp_ctx = Secp256k1::signing_only();
 		let secret_key = SecretKey::from_slice(&[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 3, self.node_secret[31]]).unwrap();
 		let pubkey_hash = WPubkeyHash::hash(&PublicKey::from_secret_key(&secp_ctx, &secret_key).serialize());
-		ShutdownScript::new_p2wpkh(&pubkey_hash)
+		Ok(ShutdownScript::new_p2wpkh(&pubkey_hash))
 	}
 }
 

fuzz/src/full_stack.rs

@@ -376,18 +376,18 @@ impl SignerProvider for KeyProvider {
 		))
 	}
 
-	fn get_destination_script(&self) -> Script {
+	fn get_destination_script(&self) -> Result<Script, ()> {
 		let secp_ctx = Secp256k1::signing_only();
 		let channel_monitor_claim_key = SecretKey::from_slice(&hex::decode("0fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff").unwrap()[..]).unwrap();
 		let our_channel_monitor_claim_key_hash = WPubkeyHash::hash(&PublicKey::from_secret_key(&secp_ctx, &channel_monitor_claim_key).serialize());
-		Builder::new().push_opcode(opcodes::all::OP_PUSHBYTES_0).push_slice(&our_channel_monitor_claim_key_hash[..]).into_script()
+		Ok(Builder::new().push_opcode(opcodes::all::OP_PUSHBYTES_0).push_slice(&our_channel_monitor_claim_key_hash[..]).into_script())
 	}
 
-	fn get_shutdown_scriptpubkey(&self) -> ShutdownScript {
+	fn get_shutdown_scriptpubkey(&self) -> Result<ShutdownScript, ()> {
 		let secp_ctx = Secp256k1::signing_only();
 		let secret_key = SecretKey::from_slice(&[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1]).unwrap();
 		let pubkey_hash = WPubkeyHash::hash(&PublicKey::from_secret_key(&secp_ctx, &secret_key).serialize());
-		ShutdownScript::new_p2wpkh(&pubkey_hash)
+		Ok(ShutdownScript::new_p2wpkh(&pubkey_hash))
 	}
 }
 

fuzz/src/onion_message.rs

@@ -141,9 +141,9 @@ impl SignerProvider for KeyProvider {
 
 	fn read_chan_signer(&self, _data: &[u8]) -> Result<EnforcingSigner, DecodeError> { unreachable!() }
 
-	fn get_destination_script(&self) -> Script { unreachable!() }
+	fn get_destination_script(&self) -> Result<Script, ()> { unreachable!() }
 
-	fn get_shutdown_scriptpubkey(&self) -> ShutdownScript { unreachable!() }
+	fn get_shutdown_scriptpubkey(&self) -> Result<ShutdownScript, ()> { unreachable!() }
 }
 
 #[cfg(test)]

lightning/src/chain/keysinterface.rs

@@ -543,15 +543,21 @@ pub trait SignerProvider {
 
 	/// Get a script pubkey which we send funds to when claiming on-chain contestable outputs.
 	///
+	/// If this function returns an error, this will result in a channel failing to open.
+	///
 	/// This method should return a different value each time it is called, to avoid linking
 	/// on-chain funds across channels as controlled to the same user.
-	fn get_destination_script(&self) -> Script;
+	fn get_destination_script(&self) -> Result<Script, ()>;
 
 	/// Get a script pubkey which we will send funds to when closing a channel.
 	///
+	/// If this function returns an error, this will result in a channel failing to open or close.
+	/// In the event of a failure when the counterparty is initiating a close, this can result in a
+	/// channel force close.
+	///
 	/// This method should return a different value each time it is called, to avoid linking
 	/// on-chain funds across channels as controlled to the same user.
-	fn get_shutdown_scriptpubkey(&self) -> ShutdownScript;
+	fn get_shutdown_scriptpubkey(&self) -> Result<ShutdownScript, ()>;
 }
 
 /// A simple implementation of [`WriteableEcdsaChannelSigner`] that just keeps the private keys in memory.
@@ -1366,12 +1372,12 @@ impl SignerProvider for KeysManager {
 		InMemorySigner::read(&mut io::Cursor::new(reader), self)
 	}
 
-	fn get_destination_script(&self) -> Script {
-		self.destination_script.clone()
+	fn get_destination_script(&self) -> Result<Script, ()> {
+		Ok(self.destination_script.clone())
 	}
 
-	fn get_shutdown_scriptpubkey(&self) -> ShutdownScript {
-		ShutdownScript::new_p2wpkh_from_pubkey(self.shutdown_pubkey.clone())
+	fn get_shutdown_scriptpubkey(&self) -> Result<ShutdownScript, ()> {
+		Ok(ShutdownScript::new_p2wpkh_from_pubkey(self.shutdown_pubkey.clone()))
 	}
 }
 
@@ -1461,11 +1467,11 @@ impl SignerProvider for PhantomKeysManager {
 		self.inner.read_chan_signer(reader)
 	}
 
-	fn get_destination_script(&self) -> Script {
+	fn get_destination_script(&self) -> Result<Script, ()> {
 		self.inner.get_destination_script()
 	}
 
-	fn get_shutdown_scriptpubkey(&self) -> ShutdownScript {
+	fn get_shutdown_scriptpubkey(&self) -> Result<ShutdownScript, ()> {
 		self.inner.get_shutdown_scriptpubkey()
 	}
 }

lightning/src/ln/channel.rs

@@ -986,7 +986,10 @@ impl<Signer: WriteableEcdsaChannelSigner> Channel<Signer> {
 		secp_ctx.seeded_randomize(&entropy_source.get_secure_random_bytes());
 
 		let shutdown_scriptpubkey = if config.channel_handshake_config.commit_upfront_shutdown_pubkey {
-			Some(signer_provider.get_shutdown_scriptpubkey())
+			match signer_provider.get_shutdown_scriptpubkey() {
+				Ok(scriptpubkey) => Some(scriptpubkey),
+				Err(_) => return Err(APIError::ChannelUnavailable { err: "Failed to get shutdown scriptpubkey".to_owned()}),
+			}
 		} else { None };
 
 		if let Some(shutdown_scriptpubkey) = &shutdown_scriptpubkey {
@@ -995,6 +998,11 @@ impl<Signer: WriteableEcdsaChannelSigner> Channel<Signer> {
 			}
 		}
 
+		let destination_script = match signer_provider.get_destination_script() {
+			Ok(script) => script,
+			Err(_) => return Err(APIError::ChannelUnavailable { err: "Failed to get destination script".to_owned()}),
+		};
+
 		let temporary_channel_id = entropy_source.get_secure_random_bytes();
 
 		Ok(Channel {
@@ -1021,7 +1029,7 @@ impl<Signer: WriteableEcdsaChannelSigner> Channel<Signer> {
 
 			holder_signer,
 			shutdown_scriptpubkey,
-			destination_script: signer_provider.get_destination_script(),
+			destination_script,
 
 			cur_holder_commitment_transaction_number: INITIAL_COMMITMENT_NUMBER,
 			cur_counterparty_commitment_transaction_number: INITIAL_COMMITMENT_NUMBER,
@@ -1333,7 +1341,10 @@ impl<Signer: WriteableEcdsaChannelSigner> Channel<Signer> {
 		} else { None };
 
 		let shutdown_scriptpubkey = if config.channel_handshake_config.commit_upfront_shutdown_pubkey {
-			Some(signer_provider.get_shutdown_scriptpubkey())
+			match signer_provider.get_shutdown_scriptpubkey() {
+				Ok(scriptpubkey) => Some(scriptpubkey),
+				Err(_) => return Err(ChannelError::Close("Failed to get upfront shutdown scriptpubkey".to_owned())),
+			}
 		} else { None };
 
 		if let Some(shutdown_scriptpubkey) = &shutdown_scriptpubkey {
@@ -1342,6 +1353,11 @@ impl<Signer: WriteableEcdsaChannelSigner> Channel<Signer> {
 			}
 		}
 
+		let destination_script = match signer_provider.get_destination_script() {
+			Ok(script) => script,
+			Err(_) => return Err(ChannelError::Close("Failed to get destination script".to_owned())),
+		};
+
 		let mut secp_ctx = Secp256k1::new();
 		secp_ctx.seeded_randomize(&entropy_source.get_secure_random_bytes());
 
@@ -1368,7 +1384,7 @@ impl<Signer: WriteableEcdsaChannelSigner> Channel<Signer> {
 
 			holder_signer,
 			shutdown_scriptpubkey,
-			destination_script: signer_provider.get_destination_script(),
+			destination_script,
 
 			cur_holder_commitment_transaction_number: INITIAL_COMMITMENT_NUMBER,
 			cur_counterparty_commitment_transaction_number: INITIAL_COMMITMENT_NUMBER,
@@ -4355,7 +4371,10 @@ impl<Signer: WriteableEcdsaChannelSigner> Channel<Signer> {
 			Some(_) => false,
 			None => {
 				assert!(send_shutdown);
-				let shutdown_scriptpubkey = signer_provider.get_shutdown_scriptpubkey();
+				let shutdown_scriptpubkey = match signer_provider.get_shutdown_scriptpubkey() {
+					Ok(scriptpubkey) => scriptpubkey,
+					Err(_) => return Err(ChannelError::Close("Failed to get shutdown scriptpubkey".to_owned())),
+				};
 				if !shutdown_scriptpubkey.is_compatible(their_features) {
 					return Err(ChannelError::Close(format!("Provided a scriptpubkey format not accepted by peer: {}", shutdown_scriptpubkey)));
 				}
@@ -6062,7 +6081,10 @@ impl<Signer: WriteableEcdsaChannelSigner> Channel<Signer> {
 		let update_shutdown_script = match self.shutdown_scriptpubkey {
 			Some(_) => false,
 			None if !chan_closed => {
-				let shutdown_scriptpubkey = signer_provider.get_shutdown_scriptpubkey();
+				let shutdown_scriptpubkey = match signer_provider.get_shutdown_scriptpubkey() {
+					Ok(scriptpubkey) => scriptpubkey,
+					Err(_) => return Err(APIError::ChannelUnavailable { err: "Failed to get shutdown scriptpubkey".to_owned() }),
+				};
 				if !shutdown_scriptpubkey.is_compatible(their_features) {
 					return Err(APIError::IncompatibleShutdownScript { script: shutdown_scriptpubkey.clone() });
 				}
@@ -7086,17 +7108,17 @@ mod tests {
 
 		fn read_chan_signer(&self, _data: &[u8]) -> Result<Self::Signer, DecodeError> { panic!(); }
 
-		fn get_destination_script(&self) -> Script {
+		fn get_destination_script(&self) -> Result<Script, ()> {
 			let secp_ctx = Secp256k1::signing_only();
 			let channel_monitor_claim_key = SecretKey::from_slice(&hex::decode("0fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff").unwrap()[..]).unwrap();
 			let channel_monitor_claim_key_hash = WPubkeyHash::hash(&PublicKey::from_secret_key(&secp_ctx, &channel_monitor_claim_key).serialize());
-			Builder::new().push_opcode(opcodes::all::OP_PUSHBYTES_0).push_slice(&channel_monitor_claim_key_hash[..]).into_script()
+			Ok(Builder::new().push_opcode(opcodes::all::OP_PUSHBYTES_0).push_slice(&channel_monitor_claim_key_hash[..]).into_script())
 		}
 
-		fn get_shutdown_scriptpubkey(&self) -> ShutdownScript {
+		fn get_shutdown_scriptpubkey(&self) -> Result<ShutdownScript, ()> {
 			let secp_ctx = Secp256k1::signing_only();
 			let channel_close_key = SecretKey::from_slice(&hex::decode("0fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff").unwrap()[..]).unwrap();
-			ShutdownScript::new_p2wpkh_from_pubkey(PublicKey::from_secret_key(&secp_ctx, &channel_close_key))
+			Ok(ShutdownScript::new_p2wpkh_from_pubkey(PublicKey::from_secret_key(&secp_ctx, &channel_close_key)))
 		}
 	}
 

lightning/src/ln/channelmanager.rs

@@ -1854,6 +1854,10 @@ where
 	/// Raises [`APIError::APIMisuseError`] when `channel_value_satoshis` > 2**24 or `push_msat` is
 	/// greater than `channel_value_satoshis * 1k` or `channel_value_satoshis < 1000`.
 	///
+	/// Raises [`APIError::ChannelUnavailable`] if the channel cannot be opened due to failing to
+	/// generate a shutdown scriptpubkey or destination script set by
+	/// [`SignerProvider::get_shutdown_scriptpubkey`] or [`SignerProvider::get_destination_script`].
+	///
 	/// Note that we do not check if you are currently connected to the given peer. If no
 	/// connection is available, the outbound `open_channel` message may fail to send, resulting in
 	/// the channel eventually being silently forgotten (dropped on reload).
@@ -2098,6 +2102,11 @@ where
 	///
 	/// May generate a [`SendShutdown`] message event on success, which should be relayed.
 	///
+	/// Raises [`APIError::ChannelUnavailable`] if the channel cannot be closed due to failing to
+	/// generate a shutdown scriptpubkey or destination script set by
+	/// [`SignerProvider::get_shutdown_scriptpubkey`]. A force-closure may be needed to close the
+	/// channel.
+	///
 	/// [`ChannelConfig::force_close_avoidance_max_fee_satoshis`]: crate::util::config::ChannelConfig::force_close_avoidance_max_fee_satoshis
 	/// [`Background`]: crate::chain::chaininterface::ConfirmationTarget::Background
 	/// [`Normal`]: crate::chain::chaininterface::ConfirmationTarget::Normal
@@ -2122,6 +2131,11 @@ where
 	///
 	/// May generate a [`SendShutdown`] message event on success, which should be relayed.
 	///
+	/// Raises [`APIError::ChannelUnavailable`] if the channel cannot be closed due to failing to
+	/// generate a shutdown scriptpubkey or destination script set by
+	/// [`SignerProvider::get_shutdown_scriptpubkey`]. A force-closure may be needed to close the
+	/// channel.
+	///
 	/// [`ChannelConfig::force_close_avoidance_max_fee_satoshis`]: crate::util::config::ChannelConfig::force_close_avoidance_max_fee_satoshis
 	/// [`Background`]: crate::chain::chaininterface::ConfirmationTarget::Background
 	/// [`Normal`]: crate::chain::chaininterface::ConfirmationTarget::Normal

lightning/src/ln/shutdown_tests.rs

@@ -669,7 +669,7 @@ fn test_unsupported_anysegwit_shutdown_script() {
 	let nodes = create_network(3, &node_cfgs, &node_chanmgrs);
 
 	// Check that using an unsupported shutdown script fails and a supported one succeeds.
-	let supported_shutdown_script = chanmon_cfgs[1].keys_manager.get_shutdown_scriptpubkey();
+	let supported_shutdown_script = chanmon_cfgs[1].keys_manager.get_shutdown_scriptpubkey().unwrap();
 	let unsupported_shutdown_script =
 		ShutdownScript::new_witness_program(WitnessVersion::V16, &[0, 40]).unwrap();
 	chanmon_cfgs[1].keys_manager

lightning/src/util/test_utils.rs

@@ -171,8 +171,8 @@ impl SignerProvider for OnlyReadsKeysInterface {
 		))
 	}
 
-	fn get_destination_script(&self) -> Script { unreachable!(); }
-	fn get_shutdown_scriptpubkey(&self) -> ShutdownScript { unreachable!(); }
+	fn get_destination_script(&self) -> Result<Script, ()> { Err(()) }
+	fn get_shutdown_scriptpubkey(&self) -> Result<ShutdownScript, ()> { Err(()) }
 }
 
 pub struct TestChainMonitor<'a> {
@@ -793,14 +793,14 @@ impl SignerProvider for TestKeysInterface {
 		))
 	}
 
-	fn get_destination_script(&self) -> Script { self.backing.get_destination_script() }
+	fn get_destination_script(&self) -> Result<Script, ()> { self.backing.get_destination_script() }
 
-	fn get_shutdown_scriptpubkey(&self) -> ShutdownScript {
+	fn get_shutdown_scriptpubkey(&self) -> Result<ShutdownScript, ()> {
 		match &mut *self.expectations.lock().unwrap() {
 			None => self.backing.get_shutdown_scriptpubkey(),
 			Some(expectations) => match expectations.pop_front() {
 				None => panic!("Unexpected get_shutdown_scriptpubkey"),
-				Some(expectation) => expectation.returns,
+				Some(expectation) => Ok(expectation.returns),
 			},
 		}
 	}