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

   1 //! Abstractions for scripts used in the Lightning Network.
   2
   3 use bitcoin::{WitnessProgram, WPubkeyHash, WScriptHash};
   4 use bitcoin::blockdata::opcodes::all::OP_PUSHBYTES_0 as SEGWIT_V0;
   5 use bitcoin::blockdata::script::{Script, ScriptBuf};
   6 use bitcoin::hashes::Hash;
   7 use bitcoin::secp256k1::PublicKey;
   8
   9 use crate::ln::channelmanager;
  10 use crate::ln::features::InitFeatures;
  11 use crate::ln::msgs::DecodeError;
  12 use crate::util::ser::{Readable, Writeable, Writer};
  13
  14 use crate::io;
  15
  16 #[allow(unused_imports)]
  17 use crate::prelude::*;
  18
  19 /// A script pubkey for shutting down a channel as defined by [BOLT #2].
  20 ///
  21 /// [BOLT #2]: https://github.com/lightning/bolts/blob/master/02-peer-protocol.md
  22 #[derive(Clone, PartialEq, Eq)]
  23 pub struct ShutdownScript(ShutdownScriptImpl);
  24
  25 /// An error occurring when converting from [`ScriptBuf`] to [`ShutdownScript`].
  26 #[derive(Clone, Debug)]
  27 pub struct InvalidShutdownScript {
  28         /// The script that did not meet the requirements from [BOLT #2].
  29         ///
  30         /// [BOLT #2]: https://github.com/lightning/bolts/blob/master/02-peer-protocol.md
  31         pub script: ScriptBuf
  32 }
  33
  34 #[derive(Clone, PartialEq, Eq)]
  35 enum ShutdownScriptImpl {
  36         /// [`PublicKey`] used to form a P2WPKH script pubkey. Used to support backward-compatible
  37         /// serialization.
  38         Legacy(PublicKey),
  39
  40         /// [`ScriptBuf`] adhering to a script pubkey format specified in BOLT #2.
  41         Bolt2(ScriptBuf),
  42 }
  43
  44 impl Writeable for ShutdownScript {
  45         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
  46                 self.0.write(w)
  47         }
  48 }
  49
  50 impl Readable for ShutdownScript {
  51         fn read<R: io::Read>(r: &mut R) -> Result<Self, DecodeError> {
  52                 Ok(ShutdownScript(ShutdownScriptImpl::read(r)?))
  53         }
  54 }
  55
  56 impl_writeable_tlv_based_enum!(ShutdownScriptImpl, ;
  57         (0, Legacy),
  58         (1, Bolt2),
  59 );
  60
  61 impl ShutdownScript {
  62         /// Generates a P2WPKH script pubkey from the given [`PublicKey`].
  63         pub(crate) fn new_p2wpkh_from_pubkey(pubkey: PublicKey) -> Self {
  64                 Self(ShutdownScriptImpl::Legacy(pubkey))
  65         }
  66
  67         /// Generates a P2WPKH script pubkey from the given [`WPubkeyHash`].
  68         pub fn new_p2wpkh(pubkey_hash: &WPubkeyHash) -> Self {
  69                 Self(ShutdownScriptImpl::Bolt2(ScriptBuf::new_p2wpkh(pubkey_hash)))
  70         }
  71
  72         /// Generates a P2WSH script pubkey from the given [`WScriptHash`].
  73         pub fn new_p2wsh(script_hash: &WScriptHash) -> Self {
  74                 Self(ShutdownScriptImpl::Bolt2(ScriptBuf::new_p2wsh(script_hash)))
  75         }
  76
  77         /// Generates a witness script pubkey from the given segwit version and program.
  78         ///
  79         /// Note for version-zero witness scripts you must use [`ShutdownScript::new_p2wpkh`] or
  80         /// [`ShutdownScript::new_p2wsh`] instead.
  81         ///
  82         /// # Errors
  83         ///
  84         /// This function may return an error if `program` is invalid for the segwit `version`.
  85         pub fn new_witness_program(witness_program: &WitnessProgram) -> Result<Self, InvalidShutdownScript> {
  86                 Self::try_from(ScriptBuf::new_witness_program(witness_program))
  87         }
  88
  89         /// Converts the shutdown script into the underlying [`ScriptBuf`].
  90         pub fn into_inner(self) -> ScriptBuf {
  91                 self.into()
  92         }
  93
  94         /// Returns the [`PublicKey`] used for a P2WPKH shutdown script if constructed directly from it.
  95         pub fn as_legacy_pubkey(&self) -> Option<&PublicKey> {
  96                 match &self.0 {
  97                         ShutdownScriptImpl::Legacy(pubkey) => Some(pubkey),
  98                         ShutdownScriptImpl::Bolt2(_) => None,
  99                 }
 100         }
 101
 102         /// Returns whether the shutdown script is compatible with the features as defined by BOLT #2.
 103         ///
 104         /// Specifically, checks for compliance with feature `option_shutdown_anysegwit`.
 105         pub fn is_compatible(&self, features: &InitFeatures) -> bool {
 106                 match &self.0 {
 107                         ShutdownScriptImpl::Legacy(_) => true,
 108                         ShutdownScriptImpl::Bolt2(script) => is_bolt2_compliant(script, features),
 109                 }
 110         }
 111 }
 112
 113 /// Check if a given script is compliant with BOLT 2's shutdown script requirements for the given
 114 /// counterparty features.
 115 pub(crate) fn is_bolt2_compliant(script: &Script, features: &InitFeatures) -> bool {
 116         if script.is_p2pkh() || script.is_p2sh() || script.is_p2wpkh() || script.is_p2wsh() {
 117                 true
 118         } else if features.supports_shutdown_anysegwit() {
 119                 script.is_witness_program() && script.as_bytes()[0] != SEGWIT_V0.to_u8()
 120         } else {
 121                 false
 122         }
 123 }
 124
 125 // Note that this is only for our own shutdown scripts. Counterparties are still allowed to send us
 126 // non-witness shutdown scripts which this rejects.
 127 impl TryFrom<ScriptBuf> for ShutdownScript {
 128         type Error = InvalidShutdownScript;
 129
 130         fn try_from(script: ScriptBuf) -> Result<Self, Self::Error> {
 131                 Self::try_from((script, &channelmanager::provided_init_features(&crate::util::config::UserConfig::default())))
 132         }
 133 }
 134
 135 // Note that this is only for our own shutdown scripts. Counterparties are still allowed to send us
 136 // non-witness shutdown scripts which this rejects.
 137 impl TryFrom<(ScriptBuf, &InitFeatures)> for ShutdownScript {
 138         type Error = InvalidShutdownScript;
 139
 140         fn try_from((script, features): (ScriptBuf, &InitFeatures)) -> Result<Self, Self::Error> {
 141                 if is_bolt2_compliant(&script, features) && script.is_witness_program() {
 142                         Ok(Self(ShutdownScriptImpl::Bolt2(script)))
 143                 } else {
 144                         Err(InvalidShutdownScript { script })
 145                 }
 146         }
 147 }
 148
 149 impl Into<ScriptBuf> for ShutdownScript {
 150         fn into(self) -> ScriptBuf {
 151                 match self.0 {
 152                         ShutdownScriptImpl::Legacy(pubkey) =>
 153                                 ScriptBuf::new_p2wpkh(&WPubkeyHash::hash(&pubkey.serialize())),
 154                         ShutdownScriptImpl::Bolt2(script_pubkey) => script_pubkey,
 155                 }
 156         }
 157 }
 158
 159 impl core::fmt::Display for ShutdownScript{
 160         fn fmt(&self, f: &mut core::fmt::Formatter) -> core::fmt::Result {
 161                 match &self.0 {
 162                         ShutdownScriptImpl::Legacy(_) => self.clone().into_inner().fmt(f),
 163                         ShutdownScriptImpl::Bolt2(script) => script.fmt(f),
 164                 }
 165         }
 166 }
 167
 168 #[cfg(test)]
 169 mod shutdown_script_tests {
 170         use super::ShutdownScript;
 171
 172         use bitcoin::{WitnessProgram, WitnessVersion};
 173         use bitcoin::blockdata::opcodes;
 174         use bitcoin::blockdata::script::{Builder, ScriptBuf};
 175         use bitcoin::secp256k1::Secp256k1;
 176         use bitcoin::secp256k1::{PublicKey, SecretKey};
 177
 178         use crate::ln::features::InitFeatures;
 179         use crate::prelude::*;
 180
 181         fn pubkey() -> bitcoin::key::PublicKey {
 182                 let secp_ctx = Secp256k1::signing_only();
 183                 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();
 184                 bitcoin::key::PublicKey::new(PublicKey::from_secret_key(&secp_ctx, &secret_key))
 185         }
 186
 187         fn redeem_script() -> ScriptBuf {
 188                 let pubkey = pubkey();
 189                 Builder::new()
 190                         .push_opcode(opcodes::all::OP_PUSHNUM_2)
 191                         .push_key(&pubkey)
 192                         .push_key(&pubkey)
 193                         .push_opcode(opcodes::all::OP_PUSHNUM_2)
 194                         .push_opcode(opcodes::all::OP_CHECKMULTISIG)
 195                         .into_script()
 196         }
 197
 198         fn any_segwit_features() -> InitFeatures {
 199                 let mut features = InitFeatures::empty();
 200                 features.set_shutdown_any_segwit_optional();
 201                 features
 202         }
 203
 204         #[test]
 205         fn generates_p2wpkh_from_pubkey() {
 206                 let pubkey = pubkey();
 207                 let pubkey_hash = pubkey.wpubkey_hash().unwrap();
 208                 let p2wpkh_script = ScriptBuf::new_p2wpkh(&pubkey_hash);
 209
 210                 let shutdown_script = ShutdownScript::new_p2wpkh_from_pubkey(pubkey.inner);
 211                 assert!(shutdown_script.is_compatible(&any_segwit_features()));
 212                 assert!(shutdown_script.is_compatible(&InitFeatures::empty()));
 213                 assert_eq!(shutdown_script.into_inner(), p2wpkh_script);
 214         }
 215
 216         #[test]
 217         fn generates_p2wpkh_from_pubkey_hash() {
 218                 let pubkey_hash = pubkey().wpubkey_hash().unwrap();
 219                 let p2wpkh_script = ScriptBuf::new_p2wpkh(&pubkey_hash);
 220
 221                 let shutdown_script = ShutdownScript::new_p2wpkh(&pubkey_hash);
 222                 assert!(shutdown_script.is_compatible(&any_segwit_features()));
 223                 assert!(shutdown_script.is_compatible(&InitFeatures::empty()));
 224                 assert_eq!(shutdown_script.into_inner(), p2wpkh_script);
 225                 assert!(ShutdownScript::try_from(p2wpkh_script).is_ok());
 226         }
 227
 228         #[test]
 229         fn generates_p2wsh_from_script_hash() {
 230                 let script_hash = redeem_script().wscript_hash();
 231                 let p2wsh_script = ScriptBuf::new_p2wsh(&script_hash);
 232
 233                 let shutdown_script = ShutdownScript::new_p2wsh(&script_hash);
 234                 assert!(shutdown_script.is_compatible(&any_segwit_features()));
 235                 assert!(shutdown_script.is_compatible(&InitFeatures::empty()));
 236                 assert_eq!(shutdown_script.into_inner(), p2wsh_script);
 237                 assert!(ShutdownScript::try_from(p2wsh_script).is_ok());
 238         }
 239
 240         #[test]
 241         fn generates_segwit_from_non_v0_witness_program() {
 242                 let witness_program = WitnessProgram::new(WitnessVersion::V16, &[0; 40]).unwrap();
 243                 let script = ScriptBuf::new_witness_program(&witness_program);
 244                 let shutdown_script = ShutdownScript::new_witness_program(&witness_program).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(), script);
 248         }
 249
 250         #[test]
 251         fn fails_from_unsupported_script() {
 252                 let op_return = ScriptBuf::new_op_return(&[0; 42]);
 253                 assert!(ShutdownScript::try_from(op_return).is_err());
 254         }
 255 }