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

   1 //! Abstractions for scripts used in the Lightning Network.
   2
   3 use bitcoin::bech32::u5;
   4 use bitcoin::blockdata::opcodes::all::OP_PUSHBYTES_0 as SEGWIT_V0;
   5 use bitcoin::blockdata::script::Script;
   6 use bitcoin::hashes::Hash;
   7 use bitcoin::hash_types::{PubkeyHash, ScriptHash, WPubkeyHash, WScriptHash};
   8 use bitcoin::secp256k1::key::PublicKey;
   9
  10 use ln::features::InitFeatures;
  11 use ln::msgs::DecodeError;
  12 use util::ser::{Readable, Writeable, Writer};
  13
  14 use std::convert::TryFrom;
  15 use std::io::Read;
  16 use core::num::NonZeroU8;
  17
  18 /// A script pubkey for shutting down a channel as defined by [BOLT #2].
  19 ///
  20 /// [BOLT #2]: https://github.com/lightningnetwork/lightning-rfc/blob/master/02-peer-protocol.md
  21 #[derive(Clone)]
  22 pub struct ShutdownScript(ShutdownScriptImpl);
  23
  24 /// An error occurring when converting from [`Script`] to [`ShutdownScript`].
  25 #[derive(Debug)]
  26 pub struct InvalidShutdownScript(Script);
  27
  28 #[derive(Clone)]
  29 enum ShutdownScriptImpl {
  30         /// [`PublicKey`] used to form a P2WPKH script pubkey. Used to support backward-compatible
  31         /// serialization.
  32         Legacy(PublicKey),
  33
  34         /// [`Script`] adhering to a script pubkey format specified in BOLT #2.
  35         Bolt2(Script),
  36 }
  37
  38 impl Writeable for ShutdownScript {
  39         fn write<W: Writer>(&self, w: &mut W) -> Result<(), ::std::io::Error> {
  40                 self.0.write(w)
  41         }
  42
  43         fn serialized_length(&self) -> usize {
  44                 self.0.serialized_length()
  45         }
  46 }
  47
  48 impl Readable for ShutdownScript {
  49         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
  50                 Ok(ShutdownScript(ShutdownScriptImpl::read(r)?))
  51         }
  52 }
  53
  54 impl_writeable_tlv_based_enum!(ShutdownScriptImpl, ;
  55         (0, Legacy),
  56         (1, Bolt2),
  57 );
  58
  59 impl ShutdownScript {
  60         /// Generates a P2WPKH script pubkey from the given [`PublicKey`].
  61         pub(crate) fn new_p2wpkh_from_pubkey(pubkey: PublicKey) -> Self {
  62                 Self(ShutdownScriptImpl::Legacy(pubkey))
  63         }
  64
  65         /// Generates a P2PKH script pubkey from the given [`PubkeyHash`].
  66         pub fn new_p2pkh(pubkey_hash: &PubkeyHash) -> Self {
  67                 Self(ShutdownScriptImpl::Bolt2(Script::new_p2pkh(pubkey_hash)))
  68         }
  69
  70         /// Generates a P2SH script pubkey from the given [`ScriptHash`].
  71         pub fn new_p2sh(script_hash: &ScriptHash) -> Self {
  72                 Self(ShutdownScriptImpl::Bolt2(Script::new_p2sh(script_hash)))
  73         }
  74
  75         /// Generates a P2WPKH script pubkey from the given [`WPubkeyHash`].
  76         pub fn new_p2wpkh(pubkey_hash: &WPubkeyHash) -> Self {
  77                 Self(ShutdownScriptImpl::Bolt2(Script::new_v0_wpkh(pubkey_hash)))
  78         }
  79
  80         /// Generates a P2WSH script pubkey from the given [`WScriptHash`].
  81         pub fn new_p2wsh(script_hash: &WScriptHash) -> Self {
  82                 Self(ShutdownScriptImpl::Bolt2(Script::new_v0_wsh(script_hash)))
  83         }
  84
  85         /// Generates a P2WSH script pubkey from the given segwit version and program.
  86         ///
  87         /// # Panics
  88         ///
  89         /// This function may panic if given a segwit program with an invalid length.
  90         pub fn new_witness_program(version: NonZeroU8, program: &[u8]) -> Self {
  91                 let version = u5::try_from_u8(version.get()).expect("Invalid segwit version");
  92                 let script = Script::new_witness_program(version, program);
  93                 Self::try_from(script).expect("Invalid segwit program")
  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 fn is_bolt2_compliant(script: &Script, features: &InitFeatures) -> bool {
 121         if script.is_p2pkh() || script.is_p2sh() || script.is_v0_p2wpkh() || script.is_v0_p2wsh() {
 122                 true
 123         } else if features.supports_shutdown_anysegwit() {
 124                 script.is_witness_program() && script.as_bytes()[0] != SEGWIT_V0.into_u8()
 125         } else {
 126                 false
 127         }
 128 }
 129
 130 impl TryFrom<Script> for ShutdownScript {
 131         type Error = InvalidShutdownScript;
 132
 133         fn try_from(script: Script) -> Result<Self, Self::Error> {
 134                 Self::try_from((script, &InitFeatures::known()))
 135         }
 136 }
 137
 138 impl TryFrom<(Script, &InitFeatures)> for ShutdownScript {
 139         type Error = InvalidShutdownScript;
 140
 141         fn try_from((script, features): (Script, &InitFeatures)) -> Result<Self, Self::Error> {
 142                 if is_bolt2_compliant(&script, features) {
 143                         Ok(Self(ShutdownScriptImpl::Bolt2(script)))
 144                 } else {
 145                         Err(InvalidShutdownScript(script))
 146                 }
 147         }
 148 }
 149
 150 impl Into<Script> for ShutdownScript {
 151         fn into(self) -> Script {
 152                 match self.0 {
 153                         ShutdownScriptImpl::Legacy(pubkey) =>
 154                                 Script::new_v0_wpkh(&WPubkeyHash::hash(&pubkey.serialize())),
 155                         ShutdownScriptImpl::Bolt2(script_pubkey) => script_pubkey,
 156                 }
 157         }
 158 }
 159
 160 #[cfg(test)]
 161 mod shutdown_script_tests {
 162         use super::ShutdownScript;
 163         use bitcoin::bech32::u5;
 164         use bitcoin::blockdata::opcodes;
 165         use bitcoin::blockdata::script::{Builder, Script};
 166         use bitcoin::secp256k1::Secp256k1;
 167         use bitcoin::secp256k1::key::{PublicKey, SecretKey};
 168         use ln::features::InitFeatures;
 169         use std::convert::TryFrom;
 170         use core::num::NonZeroU8;
 171
 172         fn pubkey() -> bitcoin::util::ecdsa::PublicKey {
 173                 let secp_ctx = Secp256k1::signing_only();
 174                 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();
 175                 bitcoin::util::ecdsa::PublicKey::new(PublicKey::from_secret_key(&secp_ctx, &secret_key))
 176         }
 177
 178         fn redeem_script() -> Script {
 179                 let pubkey = pubkey();
 180                 Builder::new()
 181                         .push_opcode(opcodes::all::OP_PUSHNUM_2)
 182                         .push_key(&pubkey)
 183                         .push_key(&pubkey)
 184                         .push_opcode(opcodes::all::OP_PUSHNUM_2)
 185                         .push_opcode(opcodes::all::OP_CHECKMULTISIG)
 186                         .into_script()
 187         }
 188
 189         #[test]
 190         fn generates_p2wpkh_from_pubkey() {
 191                 let pubkey = pubkey();
 192                 let pubkey_hash = pubkey.wpubkey_hash().unwrap();
 193                 let p2wpkh_script = Script::new_v0_wpkh(&pubkey_hash);
 194
 195                 let shutdown_script = ShutdownScript::new_p2wpkh_from_pubkey(pubkey.key);
 196                 assert!(shutdown_script.is_compatible(&InitFeatures::known()));
 197                 assert!(shutdown_script.is_compatible(&InitFeatures::known().clear_shutdown_anysegwit()));
 198                 assert_eq!(shutdown_script.into_inner(), p2wpkh_script);
 199         }
 200
 201         #[test]
 202         fn generates_p2pkh_from_pubkey_hash() {
 203                 let pubkey_hash = pubkey().pubkey_hash();
 204                 let p2pkh_script = Script::new_p2pkh(&pubkey_hash);
 205
 206                 let shutdown_script = ShutdownScript::new_p2pkh(&pubkey_hash);
 207                 assert!(shutdown_script.is_compatible(&InitFeatures::known()));
 208                 assert!(shutdown_script.is_compatible(&InitFeatures::known().clear_shutdown_anysegwit()));
 209                 assert_eq!(shutdown_script.into_inner(), p2pkh_script);
 210                 assert!(ShutdownScript::try_from(p2pkh_script).is_ok());
 211         }
 212
 213         #[test]
 214         fn generates_p2sh_from_script_hash() {
 215                 let script_hash = redeem_script().script_hash();
 216                 let p2sh_script = Script::new_p2sh(&script_hash);
 217
 218                 let shutdown_script = ShutdownScript::new_p2sh(&script_hash);
 219                 assert!(shutdown_script.is_compatible(&InitFeatures::known()));
 220                 assert!(shutdown_script.is_compatible(&InitFeatures::known().clear_shutdown_anysegwit()));
 221                 assert_eq!(shutdown_script.into_inner(), p2sh_script);
 222                 assert!(ShutdownScript::try_from(p2sh_script).is_ok());
 223         }
 224
 225         #[test]
 226         fn generates_p2wpkh_from_pubkey_hash() {
 227                 let pubkey_hash = pubkey().wpubkey_hash().unwrap();
 228                 let p2wpkh_script = Script::new_v0_wpkh(&pubkey_hash);
 229
 230                 let shutdown_script = ShutdownScript::new_p2wpkh(&pubkey_hash);
 231                 assert!(shutdown_script.is_compatible(&InitFeatures::known()));
 232                 assert!(shutdown_script.is_compatible(&InitFeatures::known().clear_shutdown_anysegwit()));
 233                 assert_eq!(shutdown_script.into_inner(), p2wpkh_script);
 234                 assert!(ShutdownScript::try_from(p2wpkh_script).is_ok());
 235         }
 236
 237         #[test]
 238         fn generates_p2wsh_from_script_hash() {
 239                 let script_hash = redeem_script().wscript_hash();
 240                 let p2wsh_script = Script::new_v0_wsh(&script_hash);
 241
 242                 let shutdown_script = ShutdownScript::new_p2wsh(&script_hash);
 243                 assert!(shutdown_script.is_compatible(&InitFeatures::known()));
 244                 assert!(shutdown_script.is_compatible(&InitFeatures::known().clear_shutdown_anysegwit()));
 245                 assert_eq!(shutdown_script.into_inner(), p2wsh_script);
 246                 assert!(ShutdownScript::try_from(p2wsh_script).is_ok());
 247         }
 248
 249         #[test]
 250         fn generates_segwit_from_non_v0_witness_program() {
 251                 let version = u5::try_from_u8(16).unwrap();
 252                 let witness_program = Script::new_witness_program(version, &[0; 40]);
 253
 254                 let version = NonZeroU8::new(version.to_u8()).unwrap();
 255                 let shutdown_script = ShutdownScript::new_witness_program(version, &[0; 40]);
 256                 assert!(shutdown_script.is_compatible(&InitFeatures::known()));
 257                 assert!(!shutdown_script.is_compatible(&InitFeatures::known().clear_shutdown_anysegwit()));
 258                 assert_eq!(shutdown_script.into_inner(), witness_program);
 259         }
 260
 261         #[test]
 262         fn fails_from_unsupported_script() {
 263                 let op_return = Script::new_op_return(&[0; 42]);
 264                 assert!(ShutdownScript::try_from(op_return).is_err());
 265         }
 266
 267         #[test]
 268         fn fails_from_invalid_segwit_v0_witness_program() {
 269                 let witness_program = Script::new_witness_program(u5::try_from_u8(0).unwrap(), &[0; 2]);
 270                 assert!(ShutdownScript::try_from(witness_program).is_err());
 271         }
 272
 273         #[test]
 274         fn fails_from_invalid_segwit_non_v0_witness_program() {
 275                 let witness_program = Script::new_witness_program(u5::try_from_u8(16).unwrap(), &[0; 42]);
 276                 assert!(ShutdownScript::try_from(witness_program).is_err());
 277         }
 278 }