_ 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::{PubkeyHash, ScriptHash, WPubkeyHash, WScriptHash};
   7 use bitcoin::secp256k1::key::PublicKey;
   8
   9 use ln::features::InitFeatures;
  10 use ln::msgs::DecodeError;
  11 use util::ser::{Readable, Writeable, Writer};
  12
  13 use core::convert::TryFrom;
  14 use core::num::NonZeroU8;
  15 use io;
  16
  17 /// A script pubkey for shutting down a channel as defined by [BOLT #2].
  18 ///
  19 /// [BOLT #2]: https://github.com/lightningnetwork/lightning-rfc/blob/master/02-peer-protocol.md
  20 #[derive(Clone)]
  21 pub struct ShutdownScript(ShutdownScriptImpl);
  22
  23 /// An error occurring when converting from [`Script`] to [`ShutdownScript`].
  24 #[derive(Debug)]
  25 pub struct InvalidShutdownScript {
  26         /// The script that did not meet the requirements from [BOLT #2].
  27         ///
  28         /// [BOLT #2]: https://github.com/lightningnetwork/lightning-rfc/blob/master/02-peer-protocol.md
  29         pub script: Script
  30 }
  31
  32 #[derive(Clone)]
  33 enum ShutdownScriptImpl {
  34         /// [`PublicKey`] used to form a P2WPKH script pubkey. Used to support backward-compatible
  35         /// serialization.
  36         Legacy(PublicKey),
  37
  38         /// [`Script`] adhering to a script pubkey format specified in BOLT #2.
  39         Bolt2(Script),
  40 }
  41
  42 impl Writeable for ShutdownScript {
  43         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
  44                 self.0.write(w)
  45         }
  46
  47         fn serialized_length(&self) -> usize {
  48                 self.0.serialized_length()
  49         }
  50 }
  51
  52 impl Readable for ShutdownScript {
  53         fn read<R: io::Read>(r: &mut R) -> Result<Self, DecodeError> {
  54                 Ok(ShutdownScript(ShutdownScriptImpl::read(r)?))
  55         }
  56 }
  57
  58 impl_writeable_tlv_based_enum!(ShutdownScriptImpl, ;
  59         (0, Legacy),
  60         (1, Bolt2),
  61 );
  62
  63 impl ShutdownScript {
  64         /// Generates a P2WPKH script pubkey from the given [`PublicKey`].
  65         pub(crate) fn new_p2wpkh_from_pubkey(pubkey: PublicKey) -> Self {
  66                 Self(ShutdownScriptImpl::Legacy(pubkey))
  67         }
  68
  69         /// Generates a P2PKH script pubkey from the given [`PubkeyHash`].
  70         pub fn new_p2pkh(pubkey_hash: &PubkeyHash) -> Self {
  71                 Self(ShutdownScriptImpl::Bolt2(Script::new_p2pkh(pubkey_hash)))
  72         }
  73
  74         /// Generates a P2SH script pubkey from the given [`ScriptHash`].
  75         pub fn new_p2sh(script_hash: &ScriptHash) -> Self {
  76                 Self(ShutdownScriptImpl::Bolt2(Script::new_p2sh(script_hash)))
  77         }
  78
  79         /// Generates a P2WPKH script pubkey from the given [`WPubkeyHash`].
  80         pub fn new_p2wpkh(pubkey_hash: &WPubkeyHash) -> Self {
  81                 Self(ShutdownScriptImpl::Bolt2(Script::new_v0_wpkh(pubkey_hash)))
  82         }
  83
  84         /// Generates a P2WSH script pubkey from the given [`WScriptHash`].
  85         pub fn new_p2wsh(script_hash: &WScriptHash) -> Self {
  86                 Self(ShutdownScriptImpl::Bolt2(Script::new_v0_wsh(script_hash)))
  87         }
  88
  89         /// Generates a P2WSH script pubkey from the given segwit version and program.
  90         ///
  91         /// # Errors
  92         ///
  93         /// This function may return an error if `program` is invalid for the segwit `version`.
  94         pub fn new_witness_program(version: NonZeroU8, program: &[u8]) -> Result<Self, InvalidShutdownScript> {
  95                 let script = Builder::new()
  96                         .push_int(version.get().into())
  97                         .push_slice(&program)
  98                         .into_script();
  99                 Self::try_from(script)
 100         }
 101
 102         /// Converts the shutdown script into the underlying [`Script`].
 103         pub fn into_inner(self) -> Script {
 104                 self.into()
 105         }
 106
 107         /// Returns the [`PublicKey`] used for a P2WPKH shutdown script if constructed directly from it.
 108         pub fn as_legacy_pubkey(&self) -> Option<&PublicKey> {
 109                 match &self.0 {
 110                         ShutdownScriptImpl::Legacy(pubkey) => Some(pubkey),
 111                         ShutdownScriptImpl::Bolt2(_) => None,
 112                 }
 113         }
 114
 115         /// Returns whether the shutdown script is compatible with the features as defined by BOLT #2.
 116         ///
 117         /// Specifically, checks for compliance with feature `option_shutdown_anysegwit`.
 118         pub fn is_compatible(&self, features: &InitFeatures) -> bool {
 119                 match &self.0 {
 120                         ShutdownScriptImpl::Legacy(_) => true,
 121                         ShutdownScriptImpl::Bolt2(script) => is_bolt2_compliant(script, features),
 122                 }
 123         }
 124 }
 125
 126 fn is_bolt2_compliant(script: &Script, features: &InitFeatures) -> bool {
 127         if script.is_p2pkh() || script.is_p2sh() || script.is_v0_p2wpkh() || script.is_v0_p2wsh() {
 128                 true
 129         } else if features.supports_shutdown_anysegwit() {
 130                 script.is_witness_program() && script.as_bytes()[0] != SEGWIT_V0.into_u8()
 131         } else {
 132                 false
 133         }
 134 }
 135
 136 impl TryFrom<Script> for ShutdownScript {
 137         type Error = InvalidShutdownScript;
 138
 139         fn try_from(script: Script) -> Result<Self, Self::Error> {
 140                 Self::try_from((script, &InitFeatures::known()))
 141         }
 142 }
 143
 144 impl 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) {
 149                         Ok(Self(ShutdownScriptImpl::Bolt2(script)))
 150                 } else {
 151                         Err(InvalidShutdownScript { script })
 152                 }
 153         }
 154 }
 155
 156 impl Into<Script> for ShutdownScript {
 157         fn into(self) -> Script {
 158                 match self.0 {
 159                         ShutdownScriptImpl::Legacy(pubkey) =>
 160                                 Script::new_v0_wpkh(&WPubkeyHash::hash(&pubkey.serialize())),
 161                         ShutdownScriptImpl::Bolt2(script_pubkey) => script_pubkey,
 162                 }
 163         }
 164 }
 165
 166 #[cfg(test)]
 167 mod shutdown_script_tests {
 168         use super::ShutdownScript;
 169         use bitcoin::bech32::u5;
 170         use bitcoin::blockdata::opcodes;
 171         use bitcoin::blockdata::script::{Builder, Script};
 172         use bitcoin::secp256k1::Secp256k1;
 173         use bitcoin::secp256k1::key::{PublicKey, SecretKey};
 174         use ln::features::InitFeatures;
 175         use core::convert::TryFrom;
 176         use core::num::NonZeroU8;
 177
 178         fn pubkey() -> bitcoin::util::ecdsa::PublicKey {
 179                 let secp_ctx = Secp256k1::signing_only();
 180                 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();
 181                 bitcoin::util::ecdsa::PublicKey::new(PublicKey::from_secret_key(&secp_ctx, &secret_key))
 182         }
 183
 184         fn redeem_script() -> Script {
 185                 let pubkey = pubkey();
 186                 Builder::new()
 187                         .push_opcode(opcodes::all::OP_PUSHNUM_2)
 188                         .push_key(&pubkey)
 189                         .push_key(&pubkey)
 190                         .push_opcode(opcodes::all::OP_PUSHNUM_2)
 191                         .push_opcode(opcodes::all::OP_CHECKMULTISIG)
 192                         .into_script()
 193         }
 194
 195         #[test]
 196         fn generates_p2wpkh_from_pubkey() {
 197                 let pubkey = pubkey();
 198                 let pubkey_hash = pubkey.wpubkey_hash().unwrap();
 199                 let p2wpkh_script = Script::new_v0_wpkh(&pubkey_hash);
 200
 201                 let shutdown_script = ShutdownScript::new_p2wpkh_from_pubkey(pubkey.key);
 202                 assert!(shutdown_script.is_compatible(&InitFeatures::known()));
 203                 assert!(shutdown_script.is_compatible(&InitFeatures::known().clear_shutdown_anysegwit()));
 204                 assert_eq!(shutdown_script.into_inner(), p2wpkh_script);
 205         }
 206
 207         #[test]
 208         fn generates_p2pkh_from_pubkey_hash() {
 209                 let pubkey_hash = pubkey().pubkey_hash();
 210                 let p2pkh_script = Script::new_p2pkh(&pubkey_hash);
 211
 212                 let shutdown_script = ShutdownScript::new_p2pkh(&pubkey_hash);
 213                 assert!(shutdown_script.is_compatible(&InitFeatures::known()));
 214                 assert!(shutdown_script.is_compatible(&InitFeatures::known().clear_shutdown_anysegwit()));
 215                 assert_eq!(shutdown_script.into_inner(), p2pkh_script);
 216                 assert!(ShutdownScript::try_from(p2pkh_script).is_ok());
 217         }
 218
 219         #[test]
 220         fn generates_p2sh_from_script_hash() {
 221                 let script_hash = redeem_script().script_hash();
 222                 let p2sh_script = Script::new_p2sh(&script_hash);
 223
 224                 let shutdown_script = ShutdownScript::new_p2sh(&script_hash);
 225                 assert!(shutdown_script.is_compatible(&InitFeatures::known()));
 226                 assert!(shutdown_script.is_compatible(&InitFeatures::known().clear_shutdown_anysegwit()));
 227                 assert_eq!(shutdown_script.into_inner(), p2sh_script);
 228                 assert!(ShutdownScript::try_from(p2sh_script).is_ok());
 229         }
 230
 231         #[test]
 232         fn generates_p2wpkh_from_pubkey_hash() {
 233                 let pubkey_hash = pubkey().wpubkey_hash().unwrap();
 234                 let p2wpkh_script = Script::new_v0_wpkh(&pubkey_hash);
 235
 236                 let shutdown_script = ShutdownScript::new_p2wpkh(&pubkey_hash);
 237                 assert!(shutdown_script.is_compatible(&InitFeatures::known()));
 238                 assert!(shutdown_script.is_compatible(&InitFeatures::known().clear_shutdown_anysegwit()));
 239                 assert_eq!(shutdown_script.into_inner(), p2wpkh_script);
 240                 assert!(ShutdownScript::try_from(p2wpkh_script).is_ok());
 241         }
 242
 243         #[test]
 244         fn generates_p2wsh_from_script_hash() {
 245                 let script_hash = redeem_script().wscript_hash();
 246                 let p2wsh_script = Script::new_v0_wsh(&script_hash);
 247
 248                 let shutdown_script = ShutdownScript::new_p2wsh(&script_hash);
 249                 assert!(shutdown_script.is_compatible(&InitFeatures::known()));
 250                 assert!(shutdown_script.is_compatible(&InitFeatures::known().clear_shutdown_anysegwit()));
 251                 assert_eq!(shutdown_script.into_inner(), p2wsh_script);
 252                 assert!(ShutdownScript::try_from(p2wsh_script).is_ok());
 253         }
 254
 255         #[test]
 256         fn generates_segwit_from_non_v0_witness_program() {
 257                 let version = u5::try_from_u8(16).unwrap();
 258                 let witness_program = Script::new_witness_program(version, &[0; 40]);
 259
 260                 let version = NonZeroU8::new(version.to_u8()).unwrap();
 261                 let shutdown_script = ShutdownScript::new_witness_program(version, &[0; 40]).unwrap();
 262                 assert!(shutdown_script.is_compatible(&InitFeatures::known()));
 263                 assert!(!shutdown_script.is_compatible(&InitFeatures::known().clear_shutdown_anysegwit()));
 264                 assert_eq!(shutdown_script.into_inner(), witness_program);
 265         }
 266
 267         #[test]
 268         fn fails_from_unsupported_script() {
 269                 let op_return = Script::new_op_return(&[0; 42]);
 270                 assert!(ShutdownScript::try_from(op_return).is_err());
 271         }
 272
 273         #[test]
 274         fn fails_from_invalid_segwit_version() {
 275                 let version = NonZeroU8::new(17).unwrap();
 276                 assert!(ShutdownScript::new_witness_program(version, &[0; 40]).is_err());
 277         }
 278
 279         #[test]
 280         fn fails_from_invalid_segwit_v0_witness_program() {
 281                 let witness_program = Script::new_witness_program(u5::try_from_u8(0).unwrap(), &[0; 2]);
 282                 assert!(ShutdownScript::try_from(witness_program).is_err());
 283         }
 284
 285         #[test]
 286         fn fails_from_invalid_segwit_non_v0_witness_program() {
 287                 let version = u5::try_from_u8(16).unwrap();
 288                 let witness_program = Script::new_witness_program(version, &[0; 42]);
 289                 assert!(ShutdownScript::try_from(witness_program).is_err());
 290
 291                 let version = NonZeroU8::new(version.to_u8()).unwrap();
 292                 assert!(ShutdownScript::new_witness_program(version, &[0; 42]).is_err());
 293         }
 294 }