lightning/ln/
script.rs

1//! Abstractions for scripts used in the Lightning Network.
2
3use bitcoin::{WitnessProgram, WPubkeyHash, WScriptHash};
4use bitcoin::opcodes::all::OP_PUSHBYTES_0 as SEGWIT_V0;
5use bitcoin::script::{Script, ScriptBuf};
6use bitcoin::hashes::Hash;
7use bitcoin::secp256k1::PublicKey;
8
9use crate::ln::channelmanager;
10use crate::types::features::InitFeatures;
11use crate::ln::msgs::DecodeError;
12use crate::util::ser::{Readable, Writeable, Writer};
13
14use crate::io;
15
16#[allow(unused_imports)]
17use crate::prelude::*;
18
19/// A script pubkey for shutting down a channel as defined by [BOLT #2].
20///
21/// [BOLT #2]: https://github.com/lightning/bolts/blob/master/02-peer-protocol.md
22#[derive(Clone, PartialEq, Eq)]
23pub struct ShutdownScript(ShutdownScriptImpl);
24
25/// An error occurring when converting from [`ScriptBuf`] to [`ShutdownScript`].
26#[derive(Clone, Debug)]
27pub struct InvalidShutdownScript {
28	/// The script that did not meet the requirements from [BOLT #2].
29	///
30	/// [BOLT #2]: https://github.com/lightning/bolts/blob/master/02-peer-protocol.md
31	pub script: ScriptBuf
32}
33
34#[derive(Clone, PartialEq, Eq)]
35enum ShutdownScriptImpl {
36	/// [`PublicKey`] used to form a P2WPKH script pubkey. Used to support backward-compatible
37	/// serialization.
38	Legacy(PublicKey),
39
40	/// [`ScriptBuf`] adhering to a script pubkey format specified in BOLT #2.
41	Bolt2(ScriptBuf),
42}
43
44impl Writeable for ShutdownScript {
45	fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
46		self.0.write(w)
47	}
48}
49
50impl Readable for ShutdownScript {
51	fn read<R: io::Read>(r: &mut R) -> Result<Self, DecodeError> {
52		Ok(ShutdownScript(ShutdownScriptImpl::read(r)?))
53	}
54}
55
56impl_writeable_tlv_based_enum_legacy!(ShutdownScriptImpl, ;
57	(0, Legacy),
58	(1, Bolt2),
59);
60
61impl ShutdownScript {
62	/// Generates a P2WPKH script pubkey from the given [`PublicKey`].
63	pub(crate) fn new_p2wpkh_from_pubkey(pubkey: PublicKey) -> Self {
64		Self(ShutdownScriptImpl::Legacy(pubkey))
65	}
66
67	/// Generates a P2WPKH script pubkey from the given [`WPubkeyHash`].
68	pub fn new_p2wpkh(pubkey_hash: &WPubkeyHash) -> Self {
69		Self(ShutdownScriptImpl::Bolt2(ScriptBuf::new_p2wpkh(pubkey_hash)))
70	}
71
72	/// Generates a P2WSH script pubkey from the given [`WScriptHash`].
73	pub fn new_p2wsh(script_hash: &WScriptHash) -> Self {
74		Self(ShutdownScriptImpl::Bolt2(ScriptBuf::new_p2wsh(script_hash)))
75	}
76
77	/// Generates a witness script pubkey from the given segwit version and program.
78	///
79	/// Note for version-zero witness scripts you must use [`ShutdownScript::new_p2wpkh`] or
80	/// [`ShutdownScript::new_p2wsh`] instead.
81	///
82	/// # Errors
83	///
84	/// This function may return an error if `program` is invalid for the segwit `version`.
85	pub fn new_witness_program(witness_program: &WitnessProgram) -> Result<Self, InvalidShutdownScript> {
86		Self::try_from(ScriptBuf::new_witness_program(witness_program))
87	}
88
89	/// Converts the shutdown script into the underlying [`ScriptBuf`].
90	pub fn into_inner(self) -> ScriptBuf {
91		self.into()
92	}
93
94	/// Returns the [`PublicKey`] used for a P2WPKH shutdown script if constructed directly from it.
95	pub fn as_legacy_pubkey(&self) -> Option<&PublicKey> {
96		match &self.0 {
97			ShutdownScriptImpl::Legacy(pubkey) => Some(pubkey),
98			ShutdownScriptImpl::Bolt2(_) => None,
99		}
100	}
101
102	/// Returns whether the shutdown script is compatible with the features as defined by BOLT #2.
103	///
104	/// Specifically, checks for compliance with feature `option_shutdown_anysegwit`.
105	pub fn is_compatible(&self, features: &InitFeatures) -> bool {
106		match &self.0 {
107			ShutdownScriptImpl::Legacy(_) => true,
108			ShutdownScriptImpl::Bolt2(script) => is_bolt2_compliant(script, features),
109		}
110	}
111}
112
113/// Check if a given script is compliant with BOLT 2's shutdown script requirements for the given
114/// counterparty features.
115pub(crate) fn is_bolt2_compliant(script: &Script, features: &InitFeatures) -> bool {
116	if script.is_p2pkh() || script.is_p2sh() || script.is_p2wpkh() || script.is_p2wsh() {
117		true
118	} else if features.supports_shutdown_anysegwit() {
119		script.is_witness_program() && script.as_bytes()[0] != SEGWIT_V0.to_u8()
120	} else {
121		false
122	}
123}
124
125// Note that this is only for our own shutdown scripts. Counterparties are still allowed to send us
126// non-witness shutdown scripts which this rejects.
127impl TryFrom<ScriptBuf> for ShutdownScript {
128	type Error = InvalidShutdownScript;
129
130	fn try_from(script: ScriptBuf) -> Result<Self, Self::Error> {
131		Self::try_from((script, &channelmanager::provided_init_features(&crate::util::config::UserConfig::default())))
132	}
133}
134
135// Note that this is only for our own shutdown scripts. Counterparties are still allowed to send us
136// non-witness shutdown scripts which this rejects.
137impl TryFrom<(ScriptBuf, &InitFeatures)> for ShutdownScript {
138	type Error = InvalidShutdownScript;
139
140	fn try_from((script, features): (ScriptBuf, &InitFeatures)) -> Result<Self, Self::Error> {
141		if is_bolt2_compliant(&script, features) && script.is_witness_program() {
142			Ok(Self(ShutdownScriptImpl::Bolt2(script)))
143		} else {
144			Err(InvalidShutdownScript { script })
145		}
146	}
147}
148
149impl Into<ScriptBuf> for ShutdownScript {
150	fn into(self) -> ScriptBuf {
151		match self.0 {
152			ShutdownScriptImpl::Legacy(pubkey) =>
153				ScriptBuf::new_p2wpkh(&WPubkeyHash::hash(&pubkey.serialize())),
154			ShutdownScriptImpl::Bolt2(script_pubkey) => script_pubkey,
155		}
156	}
157}
158
159impl core::fmt::Display for ShutdownScript{
160	fn fmt(&self, f: &mut core::fmt::Formatter) -> core::fmt::Result {
161		match &self.0 {
162			ShutdownScriptImpl::Legacy(_) => self.clone().into_inner().fmt(f),
163			ShutdownScriptImpl::Bolt2(script) => script.fmt(f),
164		}
165	}
166}
167
168#[cfg(test)]
169mod shutdown_script_tests {
170	use super::ShutdownScript;
171
172	use bitcoin::{WitnessProgram, WitnessVersion};
173	use bitcoin::opcodes;
174	use bitcoin::script::{Builder, ScriptBuf};
175	use bitcoin::secp256k1::Secp256k1;
176	use bitcoin::secp256k1::{PublicKey, SecretKey};
177
178	use crate::types::features::InitFeatures;
179	use crate::prelude::*;
180
181	fn pubkey() -> bitcoin::key::PublicKey {
182		let secp_ctx = Secp256k1::signing_only();
183		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();
184		bitcoin::key::PublicKey::new(PublicKey::from_secret_key(&secp_ctx, &secret_key))
185	}
186
187	fn redeem_script() -> ScriptBuf {
188		let pubkey = pubkey();
189		Builder::new()
190			.push_opcode(opcodes::all::OP_PUSHNUM_2)
191			.push_key(&pubkey)
192			.push_key(&pubkey)
193			.push_opcode(opcodes::all::OP_PUSHNUM_2)
194			.push_opcode(opcodes::all::OP_CHECKMULTISIG)
195			.into_script()
196	}
197
198	fn any_segwit_features() -> InitFeatures {
199		let mut features = InitFeatures::empty();
200		features.set_shutdown_any_segwit_optional();
201		features
202	}
203
204	#[test]
205	fn generates_p2wpkh_from_pubkey() {
206		let pubkey = pubkey();
207		let pubkey_hash = pubkey.wpubkey_hash().unwrap();
208		let p2wpkh_script = ScriptBuf::new_p2wpkh(&pubkey_hash);
209
210		let shutdown_script = ShutdownScript::new_p2wpkh_from_pubkey(pubkey.inner);
211		assert!(shutdown_script.is_compatible(&any_segwit_features()));
212		assert!(shutdown_script.is_compatible(&InitFeatures::empty()));
213		assert_eq!(shutdown_script.into_inner(), p2wpkh_script);
214	}
215
216	#[test]
217	fn generates_p2wpkh_from_pubkey_hash() {
218		let pubkey_hash = pubkey().wpubkey_hash().unwrap();
219		let p2wpkh_script = ScriptBuf::new_p2wpkh(&pubkey_hash);
220
221		let shutdown_script = ShutdownScript::new_p2wpkh(&pubkey_hash);
222		assert!(shutdown_script.is_compatible(&any_segwit_features()));
223		assert!(shutdown_script.is_compatible(&InitFeatures::empty()));
224		assert_eq!(shutdown_script.into_inner(), p2wpkh_script);
225		assert!(ShutdownScript::try_from(p2wpkh_script).is_ok());
226	}
227
228	#[test]
229	fn generates_p2wsh_from_script_hash() {
230		let script_hash = redeem_script().wscript_hash();
231		let p2wsh_script = ScriptBuf::new_p2wsh(&script_hash);
232
233		let shutdown_script = ShutdownScript::new_p2wsh(&script_hash);
234		assert!(shutdown_script.is_compatible(&any_segwit_features()));
235		assert!(shutdown_script.is_compatible(&InitFeatures::empty()));
236		assert_eq!(shutdown_script.into_inner(), p2wsh_script);
237		assert!(ShutdownScript::try_from(p2wsh_script).is_ok());
238	}
239
240	#[test]
241	fn generates_segwit_from_non_v0_witness_program() {
242		let witness_program = WitnessProgram::new(WitnessVersion::V16, &[0; 40]).unwrap();
243		let script = ScriptBuf::new_witness_program(&witness_program);
244		let shutdown_script = ShutdownScript::new_witness_program(&witness_program).unwrap();
245		assert!(shutdown_script.is_compatible(&any_segwit_features()));
246		assert!(!shutdown_script.is_compatible(&InitFeatures::empty()));
247		assert_eq!(shutdown_script.into_inner(), script);
248	}
249
250	#[test]
251	fn fails_from_unsupported_script() {
252		let op_return = ScriptBuf::new_op_return(&[0; 42]);
253		assert!(ShutdownScript::try_from(op_return).is_err());
254	}
255}
lightning/ln/script.rs

lightning/ln/
script.rs
