_ 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::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 P2WPKH script pubkey from the given [`WPubkeyHash`].
  70         pub fn new_p2wpkh(pubkey_hash: &WPubkeyHash) -> Self {
  71                 Self(ShutdownScriptImpl::Bolt2(Script::new_v0_wpkh(pubkey_hash)))
  72         }
  73
  74         /// Generates a P2WSH script pubkey from the given [`WScriptHash`].
  75         pub fn new_p2wsh(script_hash: &WScriptHash) -> Self {
  76                 Self(ShutdownScriptImpl::Bolt2(Script::new_v0_wsh(script_hash)))
  77         }
  78
  79         /// Generates a witness script pubkey from the given segwit version and program.
  80         ///
  81         /// Note for version-zero witness scripts you must use [`ShutdownScript::new_p2wpkh`] or
  82         /// [`ShutdownScript::new_p2wsh`] instead.
  83         ///
  84         /// # Errors
  85         ///
  86         /// This function may return an error if `program` is invalid for the segwit `version`.
  87         pub fn new_witness_program(version: NonZeroU8, program: &[u8]) -> Result<Self, InvalidShutdownScript> {
  88                 let script = Builder::new()
  89                         .push_int(version.get().into())
  90                         .push_slice(&program)
  91                         .into_script();
  92                 Self::try_from(script)
  93         }
  94
  95         /// Converts the shutdown script into the underlying [`Script`].
  96         pub fn into_inner(self) -> Script {
  97                 self.into()
  98         }
  99
 100         /// Returns the [`PublicKey`] used for a P2WPKH shutdown script if constructed directly from it.
 101         pub fn as_legacy_pubkey(&self) -> Option<&PublicKey> {
 102                 match &self.0 {
 103                         ShutdownScriptImpl::Legacy(pubkey) => Some(pubkey),
 104                         ShutdownScriptImpl::Bolt2(_) => None,
 105                 }
 106         }
 107
 108         /// Returns whether the shutdown script is compatible with the features as defined by BOLT #2.
 109         ///
 110         /// Specifically, checks for compliance with feature `option_shutdown_anysegwit`.
 111         pub fn is_compatible(&self, features: &InitFeatures) -> bool {
 112                 match &self.0 {
 113                         ShutdownScriptImpl::Legacy(_) => true,
 114                         ShutdownScriptImpl::Bolt2(script) => is_bolt2_compliant(script, features),
 115                 }
 116         }
 117 }
 118
 119 /// Check if a given script is compliant with BOLT 2's shutdown script requirements for the given
 120 /// counterparty features.
 121 pub(crate) fn is_bolt2_compliant(script: &Script, features: &InitFeatures) -> bool {
 122         if script.is_p2pkh() || script.is_p2sh() || script.is_v0_p2wpkh() || script.is_v0_p2wsh() {
 123                 true
 124         } else if features.supports_shutdown_anysegwit() {
 125                 script.is_witness_program() && script.as_bytes()[0] != SEGWIT_V0.into_u8()
 126         } else {
 127                 false
 128         }
 129 }
 130
 131 // Note that this is only for our own shutdown scripts. Counterparties are still allowed to send us
 132 // non-witness shutdown scripts which this rejects.
 133 impl TryFrom<Script> for ShutdownScript {
 134         type Error = InvalidShutdownScript;
 135
 136         fn try_from(script: Script) -> Result<Self, Self::Error> {
 137                 Self::try_from((script, &InitFeatures::known()))
 138         }
 139 }
 140
 141 // Note that this is only for our own shutdown scripts. Counterparties are still allowed to send us
 142 // non-witness shutdown scripts which this rejects.
 143 impl TryFrom<(Script, &InitFeatures)> for ShutdownScript {
 144         type Error = InvalidShutdownScript;
 145
 146         fn try_from((script, features): (Script, &InitFeatures)) -> Result<Self, Self::Error> {
 147                 if is_bolt2_compliant(&script, features) && script.is_witness_program() {
 148                         Ok(Self(ShutdownScriptImpl::Bolt2(script)))
 149                 } else {
 150                         Err(InvalidShutdownScript { script })
 151                 }
 152         }
 153 }
 154
 155 impl Into<Script> for ShutdownScript {
 156         fn into(self) -> Script {
 157                 match self.0 {
 158                         ShutdownScriptImpl::Legacy(pubkey) =>
 159                                 Script::new_v0_wpkh(&WPubkeyHash::hash(&pubkey.serialize())),
 160                         ShutdownScriptImpl::Bolt2(script_pubkey) => script_pubkey,
 161                 }
 162         }
 163 }
 164
 165 impl core::fmt::Display for ShutdownScript{
 166         fn fmt(&self, f: &mut core::fmt::Formatter) -> core::fmt::Result {
 167                 match &self.0 {
 168                         ShutdownScriptImpl::Legacy(_) => self.clone().into_inner().fmt(f),
 169                         ShutdownScriptImpl::Bolt2(script) => script.fmt(f),
 170                 }
 171         }
 172 }
 173
 174 #[cfg(test)]
 175 mod shutdown_script_tests {
 176         use super::ShutdownScript;
 177         use bitcoin::bech32::u5;
 178         use bitcoin::blockdata::opcodes;
 179         use bitcoin::blockdata::script::{Builder, Script};
 180         use bitcoin::secp256k1::Secp256k1;
 181         use bitcoin::secp256k1::key::{PublicKey, SecretKey};
 182         use ln::features::InitFeatures;
 183         use core::convert::TryFrom;
 184         use core::num::NonZeroU8;
 185
 186         fn pubkey() -> bitcoin::util::ecdsa::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::ecdsa::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         #[test]
 204         fn generates_p2wpkh_from_pubkey() {
 205                 let pubkey = pubkey();
 206                 let pubkey_hash = pubkey.wpubkey_hash().unwrap();
 207                 let p2wpkh_script = Script::new_v0_wpkh(&pubkey_hash);
 208
 209                 let shutdown_script = ShutdownScript::new_p2wpkh_from_pubkey(pubkey.key);
 210                 assert!(shutdown_script.is_compatible(&InitFeatures::known()));
 211                 assert!(shutdown_script.is_compatible(&InitFeatures::known().clear_shutdown_anysegwit()));
 212                 assert_eq!(shutdown_script.into_inner(), p2wpkh_script);
 213         }
 214
 215         #[test]
 216         fn generates_p2wpkh_from_pubkey_hash() {
 217                 let pubkey_hash = pubkey().wpubkey_hash().unwrap();
 218                 let p2wpkh_script = Script::new_v0_wpkh(&pubkey_hash);
 219
 220                 let shutdown_script = ShutdownScript::new_p2wpkh(&pubkey_hash);
 221                 assert!(shutdown_script.is_compatible(&InitFeatures::known()));
 222                 assert!(shutdown_script.is_compatible(&InitFeatures::known().clear_shutdown_anysegwit()));
 223                 assert_eq!(shutdown_script.into_inner(), p2wpkh_script);
 224                 assert!(ShutdownScript::try_from(p2wpkh_script).is_ok());
 225         }
 226
 227         #[test]
 228         fn generates_p2wsh_from_script_hash() {
 229                 let script_hash = redeem_script().wscript_hash();
 230                 let p2wsh_script = Script::new_v0_wsh(&script_hash);
 231
 232                 let shutdown_script = ShutdownScript::new_p2wsh(&script_hash);
 233                 assert!(shutdown_script.is_compatible(&InitFeatures::known()));
 234                 assert!(shutdown_script.is_compatible(&InitFeatures::known().clear_shutdown_anysegwit()));
 235                 assert_eq!(shutdown_script.into_inner(), p2wsh_script);
 236                 assert!(ShutdownScript::try_from(p2wsh_script).is_ok());
 237         }
 238
 239         #[test]
 240         fn generates_segwit_from_non_v0_witness_program() {
 241                 let version = u5::try_from_u8(16).unwrap();
 242                 let witness_program = Script::new_witness_program(version, &[0; 40]);
 243
 244                 let version = NonZeroU8::new(version.to_u8()).unwrap();
 245                 let shutdown_script = ShutdownScript::new_witness_program(version, &[0; 40]).unwrap();
 246                 assert!(shutdown_script.is_compatible(&InitFeatures::known()));
 247                 assert!(!shutdown_script.is_compatible(&InitFeatures::known().clear_shutdown_anysegwit()));
 248                 assert_eq!(shutdown_script.into_inner(), witness_program);
 249         }
 250
 251         #[test]
 252         fn fails_from_unsupported_script() {
 253                 let op_return = Script::new_op_return(&[0; 42]);
 254                 assert!(ShutdownScript::try_from(op_return).is_err());
 255         }
 256
 257         #[test]
 258         fn fails_from_invalid_segwit_version() {
 259                 let version = NonZeroU8::new(17).unwrap();
 260                 assert!(ShutdownScript::new_witness_program(version, &[0; 40]).is_err());
 261         }
 262
 263         #[test]
 264         fn fails_from_invalid_segwit_v0_witness_program() {
 265                 let witness_program = Script::new_witness_program(u5::try_from_u8(0).unwrap(), &[0; 2]);
 266                 assert!(ShutdownScript::try_from(witness_program).is_err());
 267         }
 268
 269         #[test]
 270         fn fails_from_invalid_segwit_non_v0_witness_program() {
 271                 let version = u5::try_from_u8(16).unwrap();
 272                 let witness_program = Script::new_witness_program(version, &[0; 42]);
 273                 assert!(ShutdownScript::try_from(witness_program).is_err());
 274
 275                 let version = NonZeroU8::new(version.to_u8()).unwrap();
 276                 assert!(ShutdownScript::new_witness_program(version, &[0; 42]).is_err());
 277         }
 278 }