_ Git - rust-lightning/blob - lightning/src/ln/script.rs

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