_ 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
 110 impl TryFrom<Script> for ShutdownScript {
 111         type Error = InvalidShutdownScript;
 112
 113         fn try_from(script: Script) -> Result<Self, Self::Error> {
 114                 Self::try_from((script, &InitFeatures::known()))
 115         }
 116 }
 117
 118 impl TryFrom<(Script, &InitFeatures)> for ShutdownScript {
 119         type Error = InvalidShutdownScript;
 120
 121         fn try_from((script, features): (Script, &InitFeatures)) -> Result<Self, Self::Error> {
 122                 if script.is_p2pkh() || script.is_p2sh() || script.is_v0_p2wpkh() || script.is_v0_p2wsh() {
 123                         Ok(Self(ShutdownScriptImpl::Bolt2(script)))
 124                 } else if features.supports_shutdown_anysegwit() && script.is_witness_program() && script.as_bytes()[0] != SEGWIT_V0.into_u8() {
 125                         Ok(Self(ShutdownScriptImpl::Bolt2(script)))  // option_shutdown_anysegwit
 126                 } else {
 127                         Err(InvalidShutdownScript(script))
 128                 }
 129         }
 130 }
 131
 132 impl Into<Script> for ShutdownScript {
 133         fn into(self) -> Script {
 134                 match self.0 {
 135                         ShutdownScriptImpl::Legacy(pubkey) =>
 136                                 Script::new_v0_wpkh(&WPubkeyHash::hash(&pubkey.serialize())),
 137                         ShutdownScriptImpl::Bolt2(script_pubkey) => script_pubkey,
 138                 }
 139         }
 140 }
 141
 142 #[cfg(test)]
 143 mod shutdown_script_tests {
 144         use super::ShutdownScript;
 145         use bitcoin::bech32::u5;
 146         use bitcoin::blockdata::opcodes;
 147         use bitcoin::blockdata::script::{Builder, Script};
 148         use bitcoin::secp256k1::Secp256k1;
 149         use bitcoin::secp256k1::key::{PublicKey, SecretKey};
 150         use std::convert::TryFrom;
 151
 152         fn pubkey() -> bitcoin::util::ecdsa::PublicKey {
 153                 let secp_ctx = Secp256k1::signing_only();
 154                 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();
 155                 bitcoin::util::ecdsa::PublicKey::new(PublicKey::from_secret_key(&secp_ctx, &secret_key))
 156         }
 157
 158         fn redeem_script() -> Script {
 159                 let pubkey = pubkey();
 160                 Builder::new()
 161                         .push_opcode(opcodes::all::OP_PUSHNUM_2)
 162                         .push_key(&pubkey)
 163                         .push_key(&pubkey)
 164                         .push_opcode(opcodes::all::OP_PUSHNUM_2)
 165                         .push_opcode(opcodes::all::OP_CHECKMULTISIG)
 166                         .into_script()
 167         }
 168
 169         #[test]
 170         fn generates_p2wpkh_from_pubkey() {
 171                 let pubkey = pubkey();
 172                 let pubkey_hash = pubkey.wpubkey_hash().unwrap();
 173                 let p2wpkh_script = Script::new_v0_wpkh(&pubkey_hash);
 174
 175                 let shutdown_script = ShutdownScript::new_p2wpkh_from_pubkey(pubkey.key);
 176                 assert_eq!(shutdown_script.into_inner(), p2wpkh_script);
 177         }
 178
 179         #[test]
 180         fn generates_p2pkh_from_pubkey_hash() {
 181                 let pubkey_hash = pubkey().pubkey_hash();
 182                 let p2pkh_script = Script::new_p2pkh(&pubkey_hash);
 183
 184                 let shutdown_script = ShutdownScript::new_p2pkh(&pubkey_hash);
 185                 assert_eq!(shutdown_script.into_inner(), p2pkh_script);
 186                 assert!(ShutdownScript::try_from(p2pkh_script).is_ok());
 187         }
 188
 189         #[test]
 190         fn generates_p2sh_from_script_hash() {
 191                 let script_hash = redeem_script().script_hash();
 192                 let p2sh_script = Script::new_p2sh(&script_hash);
 193
 194                 let shutdown_script = ShutdownScript::new_p2sh(&script_hash);
 195                 assert_eq!(shutdown_script.into_inner(), p2sh_script);
 196                 assert!(ShutdownScript::try_from(p2sh_script).is_ok());
 197         }
 198
 199         #[test]
 200         fn generates_p2wpkh_from_pubkey_hash() {
 201                 let pubkey_hash = pubkey().wpubkey_hash().unwrap();
 202                 let p2wpkh_script = Script::new_v0_wpkh(&pubkey_hash);
 203
 204                 let shutdown_script = ShutdownScript::new_p2wpkh(&pubkey_hash);
 205                 assert_eq!(shutdown_script.into_inner(), p2wpkh_script);
 206                 assert!(ShutdownScript::try_from(p2wpkh_script).is_ok());
 207         }
 208
 209         #[test]
 210         fn generates_p2wsh_from_script_hash() {
 211                 let script_hash = redeem_script().wscript_hash();
 212                 let p2wsh_script = Script::new_v0_wsh(&script_hash);
 213
 214                 let shutdown_script = ShutdownScript::new_p2wsh(&script_hash);
 215                 assert_eq!(shutdown_script.into_inner(), p2wsh_script);
 216                 assert!(ShutdownScript::try_from(p2wsh_script).is_ok());
 217         }
 218
 219         #[test]
 220         fn fails_from_unsupported_script() {
 221                 let op_return = Script::new_op_return(&[0; 42]);
 222                 assert!(ShutdownScript::try_from(op_return).is_err());
 223         }
 224
 225         #[test]
 226         fn fails_from_invalid_segwit_v0_program() {
 227                 let witness_program = Script::new_witness_program(u5::try_from_u8(0).unwrap(), &[0; 2]);
 228                 assert!(ShutdownScript::try_from(witness_program).is_err());
 229         }
 230 }