rgb_lightning/ln/
script.rs

1//! Abstractions for scripts used in the Lightning Network.
2
3use bitcoin::blockdata::opcodes::all::OP_PUSHBYTES_0 as SEGWIT_V0;
4use bitcoin::blockdata::script::{Builder, Script};
5use bitcoin::hashes::Hash;
6use bitcoin::hash_types::{WPubkeyHash, WScriptHash};
7use bitcoin::secp256k1::PublicKey;
8use bitcoin::util::address::WitnessVersion;
9
10use crate::ln::channelmanager;
11use crate::ln::features::InitFeatures;
12use crate::ln::msgs::DecodeError;
13use crate::util::ser::{Readable, Writeable, Writer};
14
15use core::convert::TryFrom;
16use crate::io;
17
18/// A script pubkey for shutting down a channel as defined by [BOLT #2].
19///
20/// [BOLT #2]: https://github.com/lightning/bolts/blob/master/02-peer-protocol.md
21#[derive(Clone, PartialEq, Eq)]
22pub struct ShutdownScript(ShutdownScriptImpl);
23
24/// An error occurring when converting from [`Script`] to [`ShutdownScript`].
25#[derive(Clone, Debug)]
26pub struct InvalidShutdownScript {
27	/// The script that did not meet the requirements from [BOLT #2].
28	///
29	/// [BOLT #2]: https://github.com/lightning/bolts/blob/master/02-peer-protocol.md
30	pub script: Script
31}
32
33#[derive(Clone, PartialEq, Eq)]
34enum ShutdownScriptImpl {
35	/// [`PublicKey`] used to form a P2WPKH script pubkey. Used to support backward-compatible
36	/// serialization.
37	Legacy(PublicKey),
38
39	/// [`Script`] adhering to a script pubkey format specified in BOLT #2.
40	Bolt2(Script),
41}
42
43impl Writeable for ShutdownScript {
44	fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
45		self.0.write(w)
46	}
47
48	fn serialized_length(&self) -> usize {
49		self.0.serialized_length()
50	}
51}
52
53impl Readable for ShutdownScript {
54	fn read<R: io::Read>(r: &mut R) -> Result<Self, DecodeError> {
55		Ok(ShutdownScript(ShutdownScriptImpl::read(r)?))
56	}
57}
58
59impl_writeable_tlv_based_enum!(ShutdownScriptImpl, ;
60	(0, Legacy),
61	(1, Bolt2),
62);
63
64impl ShutdownScript {
65	/// Generates a P2WPKH script pubkey from the given [`PublicKey`].
66	pub(crate) fn new_p2wpkh_from_pubkey(pubkey: PublicKey) -> Self {
67		Self(ShutdownScriptImpl::Legacy(pubkey))
68	}
69
70	/// Generates a P2WPKH script pubkey from the given [`WPubkeyHash`].
71	pub fn new_p2wpkh(pubkey_hash: &WPubkeyHash) -> Self {
72		Self(ShutdownScriptImpl::Bolt2(Script::new_v0_p2wpkh(pubkey_hash)))
73	}
74
75	/// Generates a P2WSH script pubkey from the given [`WScriptHash`].
76	pub fn new_p2wsh(script_hash: &WScriptHash) -> Self {
77		Self(ShutdownScriptImpl::Bolt2(Script::new_v0_p2wsh(script_hash)))
78	}
79
80	/// Generates a witness script pubkey from the given segwit version and program.
81	///
82	/// Note for version-zero witness scripts you must use [`ShutdownScript::new_p2wpkh`] or
83	/// [`ShutdownScript::new_p2wsh`] instead.
84	///
85	/// # Errors
86	///
87	/// This function may return an error if `program` is invalid for the segwit `version`.
88	pub fn new_witness_program(version: WitnessVersion, program: &[u8]) -> Result<Self, InvalidShutdownScript> {
89		let script = Builder::new()
90			.push_int(version as i64)
91			.push_slice(&program)
92			.into_script();
93		Self::try_from(script)
94	}
95
96	/// Converts the shutdown script into the underlying [`Script`].
97	pub fn into_inner(self) -> Script {
98		self.into()
99	}
100
101	/// Returns the [`PublicKey`] used for a P2WPKH shutdown script if constructed directly from it.
102	pub fn as_legacy_pubkey(&self) -> Option<&PublicKey> {
103		match &self.0 {
104			ShutdownScriptImpl::Legacy(pubkey) => Some(pubkey),
105			ShutdownScriptImpl::Bolt2(_) => None,
106		}
107	}
108
109	/// Returns whether the shutdown script is compatible with the features as defined by BOLT #2.
110	///
111	/// Specifically, checks for compliance with feature `option_shutdown_anysegwit`.
112	pub fn is_compatible(&self, features: &InitFeatures) -> bool {
113		match &self.0 {
114			ShutdownScriptImpl::Legacy(_) => true,
115			ShutdownScriptImpl::Bolt2(script) => is_bolt2_compliant(script, features),
116		}
117	}
118}
119
120/// Check if a given script is compliant with BOLT 2's shutdown script requirements for the given
121/// counterparty features.
122pub(crate) fn is_bolt2_compliant(script: &Script, features: &InitFeatures) -> bool {
123	if script.is_p2pkh() || script.is_p2sh() || script.is_v0_p2wpkh() || script.is_v0_p2wsh() {
124		true
125	} else if features.supports_shutdown_anysegwit() {
126		script.is_witness_program() && script.as_bytes()[0] != SEGWIT_V0.to_u8()
127	} else {
128		false
129	}
130}
131
132// Note that this is only for our own shutdown scripts. Counterparties are still allowed to send us
133// non-witness shutdown scripts which this rejects.
134impl TryFrom<Script> for ShutdownScript {
135	type Error = InvalidShutdownScript;
136
137	fn try_from(script: Script) -> Result<Self, Self::Error> {
138		Self::try_from((script, &channelmanager::provided_init_features()))
139	}
140}
141
142// Note that this is only for our own shutdown scripts. Counterparties are still allowed to send us
143// non-witness shutdown scripts which this rejects.
144impl TryFrom<(Script, &InitFeatures)> for ShutdownScript {
145	type Error = InvalidShutdownScript;
146
147	fn try_from((script, features): (Script, &InitFeatures)) -> Result<Self, Self::Error> {
148		if is_bolt2_compliant(&script, features) && script.is_witness_program() {
149			Ok(Self(ShutdownScriptImpl::Bolt2(script)))
150		} else {
151			Err(InvalidShutdownScript { script })
152		}
153	}
154}
155
156impl Into<Script> for ShutdownScript {
157	fn into(self) -> Script {
158		match self.0 {
159			ShutdownScriptImpl::Legacy(pubkey) =>
160				Script::new_v0_p2wpkh(&WPubkeyHash::hash(&pubkey.serialize())),
161			ShutdownScriptImpl::Bolt2(script_pubkey) => script_pubkey,
162		}
163	}
164}
165
166impl core::fmt::Display for ShutdownScript{
167	fn fmt(&self, f: &mut core::fmt::Formatter) -> core::fmt::Result {
168		match &self.0 {
169			ShutdownScriptImpl::Legacy(_) => self.clone().into_inner().fmt(f),
170			ShutdownScriptImpl::Bolt2(script) => script.fmt(f),
171		}
172	}
173}
174
175#[cfg(test)]
176mod shutdown_script_tests {
177	use super::ShutdownScript;
178	use bitcoin::blockdata::opcodes;
179	use bitcoin::blockdata::script::{Builder, Script};
180	use bitcoin::secp256k1::Secp256k1;
181	use bitcoin::secp256k1::{PublicKey, SecretKey};
182	use crate::ln::features::InitFeatures;
183	use core::convert::TryFrom;
184	use bitcoin::util::address::WitnessVersion;
185
186	fn pubkey() -> bitcoin::util::key::PublicKey {
187		let secp_ctx = Secp256k1::signing_only();
188		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();
189		bitcoin::util::key::PublicKey::new(PublicKey::from_secret_key(&secp_ctx, &secret_key))
190	}
191
192	fn redeem_script() -> Script {
193		let pubkey = pubkey();
194		Builder::new()
195			.push_opcode(opcodes::all::OP_PUSHNUM_2)
196			.push_key(&pubkey)
197			.push_key(&pubkey)
198			.push_opcode(opcodes::all::OP_PUSHNUM_2)
199			.push_opcode(opcodes::all::OP_CHECKMULTISIG)
200			.into_script()
201	}
202
203	fn any_segwit_features() -> InitFeatures {
204		let mut features = InitFeatures::empty();
205		features.set_shutdown_any_segwit_optional();
206		features
207	}
208
209	#[test]
210	fn generates_p2wpkh_from_pubkey() {
211		let pubkey = pubkey();
212		let pubkey_hash = pubkey.wpubkey_hash().unwrap();
213		let p2wpkh_script = Script::new_v0_p2wpkh(&pubkey_hash);
214
215		let shutdown_script = ShutdownScript::new_p2wpkh_from_pubkey(pubkey.inner);
216		assert!(shutdown_script.is_compatible(&any_segwit_features()));
217		assert!(shutdown_script.is_compatible(&InitFeatures::empty()));
218		assert_eq!(shutdown_script.into_inner(), p2wpkh_script);
219	}
220
221	#[test]
222	fn generates_p2wpkh_from_pubkey_hash() {
223		let pubkey_hash = pubkey().wpubkey_hash().unwrap();
224		let p2wpkh_script = Script::new_v0_p2wpkh(&pubkey_hash);
225
226		let shutdown_script = ShutdownScript::new_p2wpkh(&pubkey_hash);
227		assert!(shutdown_script.is_compatible(&any_segwit_features()));
228		assert!(shutdown_script.is_compatible(&InitFeatures::empty()));
229		assert_eq!(shutdown_script.into_inner(), p2wpkh_script);
230		assert!(ShutdownScript::try_from(p2wpkh_script).is_ok());
231	}
232
233	#[test]
234	fn generates_p2wsh_from_script_hash() {
235		let script_hash = redeem_script().wscript_hash();
236		let p2wsh_script = Script::new_v0_p2wsh(&script_hash);
237
238		let shutdown_script = ShutdownScript::new_p2wsh(&script_hash);
239		assert!(shutdown_script.is_compatible(&any_segwit_features()));
240		assert!(shutdown_script.is_compatible(&InitFeatures::empty()));
241		assert_eq!(shutdown_script.into_inner(), p2wsh_script);
242		assert!(ShutdownScript::try_from(p2wsh_script).is_ok());
243	}
244
245	#[test]
246	fn generates_segwit_from_non_v0_witness_program() {
247		let witness_program = Script::new_witness_program(WitnessVersion::V16, &[0; 40]);
248		let shutdown_script = ShutdownScript::new_witness_program(WitnessVersion::V16, &[0; 40]).unwrap();
249		assert!(shutdown_script.is_compatible(&any_segwit_features()));
250		assert!(!shutdown_script.is_compatible(&InitFeatures::empty()));
251		assert_eq!(shutdown_script.into_inner(), witness_program);
252	}
253
254	#[test]
255	fn fails_from_unsupported_script() {
256		let op_return = Script::new_op_return(&[0; 42]);
257		assert!(ShutdownScript::try_from(op_return).is_err());
258	}
259
260	#[test]
261	fn fails_from_invalid_segwit_v0_witness_program() {
262		let witness_program = Script::new_witness_program(WitnessVersion::V0, &[0; 2]);
263		assert!(ShutdownScript::try_from(witness_program).is_err());
264	}
265
266	#[test]
267	fn fails_from_invalid_segwit_non_v0_witness_program() {
268		let witness_program = Script::new_witness_program(WitnessVersion::V16, &[0; 42]);
269		assert!(ShutdownScript::try_from(witness_program).is_err());
270
271		assert!(ShutdownScript::new_witness_program(WitnessVersion::V16, &[0; 42]).is_err());
272	}
273}
rgb_lightning/ln/script.rs

rgb_lightning/ln/
script.rs
