_ 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 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 [`ScriptBuf`] 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: ScriptBuf
  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         /// [`ScriptBuf`] adhering to a script pubkey format specified in BOLT #2.
  40         Bolt2(ScriptBuf),
  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(ScriptBuf::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(ScriptBuf::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(witness_program: &WitnessProgram) -> Result<Self, InvalidShutdownScript> {
  85                 Self::try_from(ScriptBuf::new_witness_program(witness_program))
  86         }
  87
  88         /// Converts the shutdown script into the underlying [`ScriptBuf`].
  89         pub fn into_inner(self) -> ScriptBuf {
  90                 self.into()
  91         }
  92
  93         /// Returns the [`PublicKey`] used for a P2WPKH shutdown script if constructed directly from it.
  94         pub fn as_legacy_pubkey(&self) -> Option<&PublicKey> {
  95                 match &self.0 {
  96                         ShutdownScriptImpl::Legacy(pubkey) => Some(pubkey),
  97                         ShutdownScriptImpl::Bolt2(_) => None,
  98                 }
  99         }
 100
 101         /// Returns whether the shutdown script is compatible with the features as defined by BOLT #2.
 102         ///
 103         /// Specifically, checks for compliance with feature `option_shutdown_anysegwit`.
 104         pub fn is_compatible(&self, features: &InitFeatures) -> bool {
 105                 match &self.0 {
 106                         ShutdownScriptImpl::Legacy(_) => true,
 107                         ShutdownScriptImpl::Bolt2(script) => is_bolt2_compliant(script, features),
 108                 }
 109         }
 110 }
 111
 112 /// Check if a given script is compliant with BOLT 2's shutdown script requirements for the given
 113 /// counterparty features.
 114 pub(crate) fn is_bolt2_compliant(script: &Script, features: &InitFeatures) -> bool {
 115         if script.is_p2pkh() || script.is_p2sh() || script.is_v0_p2wpkh() || script.is_v0_p2wsh() {
 116                 true
 117         } else if features.supports_shutdown_anysegwit() {
 118                 script.is_witness_program() && script.as_bytes()[0] != SEGWIT_V0.to_u8()
 119         } else {
 120                 false
 121         }
 122 }
 123
 124 // Note that this is only for our own shutdown scripts. Counterparties are still allowed to send us
 125 // non-witness shutdown scripts which this rejects.
 126 impl TryFrom<ScriptBuf> for ShutdownScript {
 127         type Error = InvalidShutdownScript;
 128
 129         fn try_from(script: ScriptBuf) -> Result<Self, Self::Error> {
 130                 Self::try_from((script, &channelmanager::provided_init_features(&crate::util::config::UserConfig::default())))
 131         }
 132 }
 133
 134 // Note that this is only for our own shutdown scripts. Counterparties are still allowed to send us
 135 // non-witness shutdown scripts which this rejects.
 136 impl TryFrom<(ScriptBuf, &InitFeatures)> for ShutdownScript {
 137         type Error = InvalidShutdownScript;
 138
 139         fn try_from((script, features): (ScriptBuf, &InitFeatures)) -> Result<Self, Self::Error> {
 140                 if is_bolt2_compliant(&script, features) && script.is_witness_program() {
 141                         Ok(Self(ShutdownScriptImpl::Bolt2(script)))
 142                 } else {
 143                         Err(InvalidShutdownScript { script })
 144                 }
 145         }
 146 }
 147
 148 impl Into<ScriptBuf> for ShutdownScript {
 149         fn into(self) -> ScriptBuf {
 150                 match self.0 {
 151                         ShutdownScriptImpl::Legacy(pubkey) =>
 152                                 ScriptBuf::new_v0_p2wpkh(&WPubkeyHash::hash(&pubkey.serialize())),
 153                         ShutdownScriptImpl::Bolt2(script_pubkey) => script_pubkey,
 154                 }
 155         }
 156 }
 157
 158 impl core::fmt::Display for ShutdownScript{
 159         fn fmt(&self, f: &mut core::fmt::Formatter) -> core::fmt::Result {
 160                 match &self.0 {
 161                         ShutdownScriptImpl::Legacy(_) => self.clone().into_inner().fmt(f),
 162                         ShutdownScriptImpl::Bolt2(script) => script.fmt(f),
 163                 }
 164         }
 165 }
 166
 167 #[cfg(test)]
 168 mod shutdown_script_tests {
 169         use super::ShutdownScript;
 170         use bitcoin::blockdata::opcodes;
 171         use bitcoin::blockdata::script::{Builder, ScriptBuf};
 172         use bitcoin::secp256k1::Secp256k1;
 173         use bitcoin::secp256k1::{PublicKey, SecretKey};
 174         use crate::ln::features::InitFeatures;
 175         use core::convert::TryFrom;
 176         use bitcoin::address::{WitnessProgram, WitnessVersion};
 177
 178         fn pubkey() -> bitcoin::key::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::key::PublicKey::new(PublicKey::from_secret_key(&secp_ctx, &secret_key))
 182         }
 183
 184         fn redeem_script() -> ScriptBuf {
 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         fn any_segwit_features() -> InitFeatures {
 196                 let mut features = InitFeatures::empty();
 197                 features.set_shutdown_any_segwit_optional();
 198                 features
 199         }
 200
 201         #[test]
 202         fn generates_p2wpkh_from_pubkey() {
 203                 let pubkey = pubkey();
 204                 let pubkey_hash = pubkey.wpubkey_hash().unwrap();
 205                 let p2wpkh_script = ScriptBuf::new_v0_p2wpkh(&pubkey_hash);
 206
 207                 let shutdown_script = ShutdownScript::new_p2wpkh_from_pubkey(pubkey.inner);
 208                 assert!(shutdown_script.is_compatible(&any_segwit_features()));
 209                 assert!(shutdown_script.is_compatible(&InitFeatures::empty()));
 210                 assert_eq!(shutdown_script.into_inner(), p2wpkh_script);
 211         }
 212
 213         #[test]
 214         fn generates_p2wpkh_from_pubkey_hash() {
 215                 let pubkey_hash = pubkey().wpubkey_hash().unwrap();
 216                 let p2wpkh_script = ScriptBuf::new_v0_p2wpkh(&pubkey_hash);
 217
 218                 let shutdown_script = ShutdownScript::new_p2wpkh(&pubkey_hash);
 219                 assert!(shutdown_script.is_compatible(&any_segwit_features()));
 220                 assert!(shutdown_script.is_compatible(&InitFeatures::empty()));
 221                 assert_eq!(shutdown_script.into_inner(), p2wpkh_script);
 222                 assert!(ShutdownScript::try_from(p2wpkh_script).is_ok());
 223         }
 224
 225         #[test]
 226         fn generates_p2wsh_from_script_hash() {
 227                 let script_hash = redeem_script().wscript_hash();
 228                 let p2wsh_script = ScriptBuf::new_v0_p2wsh(&script_hash);
 229
 230                 let shutdown_script = ShutdownScript::new_p2wsh(&script_hash);
 231                 assert!(shutdown_script.is_compatible(&any_segwit_features()));
 232                 assert!(shutdown_script.is_compatible(&InitFeatures::empty()));
 233                 assert_eq!(shutdown_script.into_inner(), p2wsh_script);
 234                 assert!(ShutdownScript::try_from(p2wsh_script).is_ok());
 235         }
 236
 237         #[test]
 238         fn generates_segwit_from_non_v0_witness_program() {
 239                 let witness_program = WitnessProgram::new(WitnessVersion::V16, &[0; 40]).unwrap();
 240                 let script = ScriptBuf::new_witness_program(&witness_program);
 241                 let shutdown_script = ShutdownScript::new_witness_program(&witness_program).unwrap();
 242                 assert!(shutdown_script.is_compatible(&any_segwit_features()));
 243                 assert!(!shutdown_script.is_compatible(&InitFeatures::empty()));
 244                 assert_eq!(shutdown_script.into_inner(), script);
 245         }
 246
 247         #[test]
 248         fn fails_from_unsupported_script() {
 249                 let op_return = ScriptBuf::new_op_return(&[0; 42]);
 250                 assert!(ShutdownScript::try_from(op_return).is_err());
 251         }
 252 }