_ 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 ln::channelmanager;
  11 use ln::features::InitFeatures;
  12 use ln::msgs::DecodeError;
  13 use util::ser::{Readable, Writeable, Writer};
  14
  15 use core::convert::TryFrom;
  16 use 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)]
  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)]
  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         fn serialized_length(&self) -> usize {
  49                 self.0.serialized_length()
  50         }
  51 }
  52
  53 impl Readable for ShutdownScript {
  54         fn read<R: io::Read>(r: &mut R) -> Result<Self, DecodeError> {
  55                 Ok(ShutdownScript(ShutdownScriptImpl::read(r)?))
  56         }
  57 }
  58
  59 impl_writeable_tlv_based_enum!(ShutdownScriptImpl, ;
  60         (0, Legacy),
  61         (1, Bolt2),
  62 );
  63
  64 impl 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.
 122 pub(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.
 134 impl 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.
 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) && script.is_witness_program() {
 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_p2wpkh(&WPubkeyHash::hash(&pubkey.serialize())),
 161                         ShutdownScriptImpl::Bolt2(script_pubkey) => script_pubkey,
 162                 }
 163         }
 164 }
 165
 166 impl 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)]
 176 mod 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 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 }