_ 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::{Script, ScriptBuf};
   5 use bitcoin::hashes::Hash;
   6 use bitcoin::hash_types::{WPubkeyHash, WScriptHash};
   7 use bitcoin::secp256k1::PublicKey;
   8 use bitcoin::address::WitnessProgram;
   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 crate::io;
  16
  17 #[allow(unused_imports)]
  18 use crate::prelude::*;
  19
  20 /// A script pubkey for shutting down a channel as defined by [BOLT #2].
  21 ///
  22 /// [BOLT #2]: https://github.com/lightning/bolts/blob/master/02-peer-protocol.md
  23 #[derive(Clone, PartialEq, Eq)]
  24 pub struct ShutdownScript(ShutdownScriptImpl);
  25
  26 /// An error occurring when converting from [`ScriptBuf`] to [`ShutdownScript`].
  27 #[derive(Clone, Debug)]
  28 pub struct InvalidShutdownScript {
  29         /// The script that did not meet the requirements from [BOLT #2].
  30         ///
  31         /// [BOLT #2]: https://github.com/lightning/bolts/blob/master/02-peer-protocol.md
  32         pub script: ScriptBuf
  33 }
  34
  35 #[derive(Clone, PartialEq, Eq)]
  36 enum ShutdownScriptImpl {
  37         /// [`PublicKey`] used to form a P2WPKH script pubkey. Used to support backward-compatible
  38         /// serialization.
  39         Legacy(PublicKey),
  40
  41         /// [`ScriptBuf`] adhering to a script pubkey format specified in BOLT #2.
  42         Bolt2(ScriptBuf),
  43 }
  44
  45 impl Writeable for ShutdownScript {
  46         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
  47                 self.0.write(w)
  48         }
  49 }
  50
  51 impl Readable for ShutdownScript {
  52         fn read<R: io::Read>(r: &mut R) -> Result<Self, DecodeError> {
  53                 Ok(ShutdownScript(ShutdownScriptImpl::read(r)?))
  54         }
  55 }
  56
  57 impl_writeable_tlv_based_enum!(ShutdownScriptImpl, ;
  58         (0, Legacy),
  59         (1, Bolt2),
  60 );
  61
  62 impl ShutdownScript {
  63         /// Generates a P2WPKH script pubkey from the given [`PublicKey`].
  64         pub(crate) fn new_p2wpkh_from_pubkey(pubkey: PublicKey) -> Self {
  65                 Self(ShutdownScriptImpl::Legacy(pubkey))
  66         }
  67
  68         /// Generates a P2WPKH script pubkey from the given [`WPubkeyHash`].
  69         pub fn new_p2wpkh(pubkey_hash: &WPubkeyHash) -> Self {
  70                 Self(ShutdownScriptImpl::Bolt2(ScriptBuf::new_v0_p2wpkh(pubkey_hash)))
  71         }
  72
  73         /// Generates a P2WSH script pubkey from the given [`WScriptHash`].
  74         pub fn new_p2wsh(script_hash: &WScriptHash) -> Self {
  75                 Self(ShutdownScriptImpl::Bolt2(ScriptBuf::new_v0_p2wsh(script_hash)))
  76         }
  77
  78         /// Generates a witness script pubkey from the given segwit version and program.
  79         ///
  80         /// Note for version-zero witness scripts you must use [`ShutdownScript::new_p2wpkh`] or
  81         /// [`ShutdownScript::new_p2wsh`] instead.
  82         ///
  83         /// # Errors
  84         ///
  85         /// This function may return an error if `program` is invalid for the segwit `version`.
  86         pub fn new_witness_program(witness_program: &WitnessProgram) -> Result<Self, InvalidShutdownScript> {
  87                 Self::try_from(ScriptBuf::new_witness_program(witness_program))
  88         }
  89
  90         /// Converts the shutdown script into the underlying [`ScriptBuf`].
  91         pub fn into_inner(self) -> ScriptBuf {
  92                 self.into()
  93         }
  94
  95         /// Returns the [`PublicKey`] used for a P2WPKH shutdown script if constructed directly from it.
  96         pub fn as_legacy_pubkey(&self) -> Option<&PublicKey> {
  97                 match &self.0 {
  98                         ShutdownScriptImpl::Legacy(pubkey) => Some(pubkey),
  99                         ShutdownScriptImpl::Bolt2(_) => None,
 100                 }
 101         }
 102
 103         /// Returns whether the shutdown script is compatible with the features as defined by BOLT #2.
 104         ///
 105         /// Specifically, checks for compliance with feature `option_shutdown_anysegwit`.
 106         pub fn is_compatible(&self, features: &InitFeatures) -> bool {
 107                 match &self.0 {
 108                         ShutdownScriptImpl::Legacy(_) => true,
 109                         ShutdownScriptImpl::Bolt2(script) => is_bolt2_compliant(script, features),
 110                 }
 111         }
 112 }
 113
 114 /// Check if a given script is compliant with BOLT 2's shutdown script requirements for the given
 115 /// counterparty features.
 116 pub(crate) fn is_bolt2_compliant(script: &Script, features: &InitFeatures) -> bool {
 117         if script.is_p2pkh() || script.is_p2sh() || script.is_v0_p2wpkh() || script.is_v0_p2wsh() {
 118                 true
 119         } else if features.supports_shutdown_anysegwit() {
 120                 script.is_witness_program() && script.as_bytes()[0] != SEGWIT_V0.to_u8()
 121         } else {
 122                 false
 123         }
 124 }
 125
 126 // Note that this is only for our own shutdown scripts. Counterparties are still allowed to send us
 127 // non-witness shutdown scripts which this rejects.
 128 impl TryFrom<ScriptBuf> for ShutdownScript {
 129         type Error = InvalidShutdownScript;
 130
 131         fn try_from(script: ScriptBuf) -> Result<Self, Self::Error> {
 132                 Self::try_from((script, &channelmanager::provided_init_features(&crate::util::config::UserConfig::default())))
 133         }
 134 }
 135
 136 // Note that this is only for our own shutdown scripts. Counterparties are still allowed to send us
 137 // non-witness shutdown scripts which this rejects.
 138 impl TryFrom<(ScriptBuf, &InitFeatures)> for ShutdownScript {
 139         type Error = InvalidShutdownScript;
 140
 141         fn try_from((script, features): (ScriptBuf, &InitFeatures)) -> Result<Self, Self::Error> {
 142                 if is_bolt2_compliant(&script, features) && script.is_witness_program() {
 143                         Ok(Self(ShutdownScriptImpl::Bolt2(script)))
 144                 } else {
 145                         Err(InvalidShutdownScript { script })
 146                 }
 147         }
 148 }
 149
 150 impl Into<ScriptBuf> for ShutdownScript {
 151         fn into(self) -> ScriptBuf {
 152                 match self.0 {
 153                         ShutdownScriptImpl::Legacy(pubkey) =>
 154                                 ScriptBuf::new_v0_p2wpkh(&WPubkeyHash::hash(&pubkey.serialize())),
 155                         ShutdownScriptImpl::Bolt2(script_pubkey) => script_pubkey,
 156                 }
 157         }
 158 }
 159
 160 impl core::fmt::Display for ShutdownScript{
 161         fn fmt(&self, f: &mut core::fmt::Formatter) -> core::fmt::Result {
 162                 match &self.0 {
 163                         ShutdownScriptImpl::Legacy(_) => self.clone().into_inner().fmt(f),
 164                         ShutdownScriptImpl::Bolt2(script) => script.fmt(f),
 165                 }
 166         }
 167 }
 168
 169 #[cfg(test)]
 170 mod shutdown_script_tests {
 171         use super::ShutdownScript;
 172
 173         use bitcoin::address::{WitnessProgram, WitnessVersion};
 174         use bitcoin::blockdata::opcodes;
 175         use bitcoin::blockdata::script::{Builder, ScriptBuf};
 176         use bitcoin::secp256k1::Secp256k1;
 177         use bitcoin::secp256k1::{PublicKey, SecretKey};
 178
 179         use crate::ln::features::InitFeatures;
 180         use crate::prelude::*;
 181
 182         fn pubkey() -> bitcoin::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::key::PublicKey::new(PublicKey::from_secret_key(&secp_ctx, &secret_key))
 186         }
 187
 188         fn redeem_script() -> ScriptBuf {
 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 = ScriptBuf::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 = ScriptBuf::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 = ScriptBuf::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 = WitnessProgram::new(WitnessVersion::V16, &[0; 40]).unwrap();
 244                 let script = ScriptBuf::new_witness_program(&witness_program);
 245                 let shutdown_script = ShutdownScript::new_witness_program(&witness_program).unwrap();
 246                 assert!(shutdown_script.is_compatible(&any_segwit_features()));
 247                 assert!(!shutdown_script.is_compatible(&InitFeatures::empty()));
 248                 assert_eq!(shutdown_script.into_inner(), script);
 249         }
 250
 251         #[test]
 252         fn fails_from_unsupported_script() {
 253                 let op_return = ScriptBuf::new_op_return(&[0; 42]);
 254                 assert!(ShutdownScript::try_from(op_return).is_err());
 255         }
 256 }