_ Git - rust-lightning/blob - lightning/src/util/test_channel_signer.rs

   1 // This file is Copyright its original authors, visible in version control
   2 // history.
   3 //
   4 // This file is licensed under the Apache License, Version 2.0 <LICENSE-APACHE
   5 // or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   6 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option.
   7 // You may not use this file except in accordance with one or both of these
   8 // licenses.
   9
  10 use crate::ln::channel::{ANCHOR_OUTPUT_VALUE_SATOSHI, MIN_CHAN_DUST_LIMIT_SATOSHIS};
  11 use crate::ln::chan_utils::{HTLCOutputInCommitment, ChannelPublicKeys, HolderCommitmentTransaction, CommitmentTransaction, ChannelTransactionParameters, TrustedCommitmentTransaction, ClosingTransaction};
  12 use crate::ln::{chan_utils, msgs, PaymentPreimage};
  13 use crate::sign::{WriteableEcdsaChannelSigner, InMemorySigner, ChannelSigner, EcdsaChannelSigner};
  14
  15 use crate::prelude::*;
  16 use core::cmp;
  17 use crate::sync::{Mutex, Arc};
  18 #[cfg(test)] use crate::sync::MutexGuard;
  19
  20 use bitcoin::blockdata::transaction::{Transaction, EcdsaSighashType};
  21 use bitcoin::util::sighash;
  22
  23 use bitcoin::secp256k1;
  24 use bitcoin::secp256k1::{SecretKey, PublicKey};
  25 use bitcoin::secp256k1::{Secp256k1, ecdsa::Signature};
  26 use crate::sign::HTLCDescriptor;
  27 use crate::util::ser::{Writeable, Writer};
  28 use crate::io::Error;
  29 use crate::ln::features::ChannelTypeFeatures;
  30
  31 /// Initial value for revoked commitment downward counter
  32 pub const INITIAL_REVOKED_COMMITMENT_NUMBER: u64 = 1 << 48;
  33
  34 /// An implementation of Sign that enforces some policy checks.  The current checks
  35 /// are an incomplete set.  They include:
  36 ///
  37 /// - When signing, the holder transaction has not been revoked
  38 /// - When revoking, the holder transaction has not been signed
  39 /// - The holder commitment number is monotonic and without gaps
  40 /// - The revoked holder commitment number is monotonic and without gaps
  41 /// - There is at least one unrevoked holder transaction at all times
  42 /// - The counterparty commitment number is monotonic and without gaps
  43 /// - The pre-derived keys and pre-built transaction in CommitmentTransaction were correctly built
  44 ///
  45 /// Eventually we will probably want to expose a variant of this which would essentially
  46 /// be what you'd want to run on a hardware wallet.
  47 ///
  48 /// Note that counterparty signatures on the holder transaction are not checked, but it should
  49 /// be in a complete implementation.
  50 ///
  51 /// Note that before we do so we should ensure its serialization format has backwards- and
  52 /// forwards-compatibility prefix/suffixes!
  53 #[derive(Clone)]
  54 pub struct TestChannelSigner {
  55         pub inner: InMemorySigner,
  56         /// Channel state used for policy enforcement
  57         pub state: Arc<Mutex<EnforcementState>>,
  58         pub disable_revocation_policy_check: bool,
  59         /// When `true` (the default), the signer will respond immediately with signatures. When `false`,
  60         /// the signer will return an error indicating that it is unavailable.
  61         pub available: Arc<Mutex<bool>>,
  62 }
  63
  64 impl PartialEq for TestChannelSigner {
  65         fn eq(&self, o: &Self) -> bool {
  66                 Arc::ptr_eq(&self.state, &o.state)
  67         }
  68 }
  69
  70 impl TestChannelSigner {
  71         /// Construct an TestChannelSigner
  72         pub fn new(inner: InMemorySigner) -> Self {
  73                 let state = Arc::new(Mutex::new(EnforcementState::new()));
  74                 Self {
  75                         inner,
  76                         state,
  77                         disable_revocation_policy_check: false,
  78                         available: Arc::new(Mutex::new(true)),
  79                 }
  80         }
  81
  82         /// Construct an TestChannelSigner with externally managed storage
  83         ///
  84         /// Since there are multiple copies of this struct for each channel, some coordination is needed
  85         /// so that all copies are aware of enforcement state.  A pointer to this state is provided
  86         /// here, usually by an implementation of KeysInterface.
  87         pub fn new_with_revoked(inner: InMemorySigner, state: Arc<Mutex<EnforcementState>>, disable_revocation_policy_check: bool) -> Self {
  88                 Self {
  89                         inner,
  90                         state,
  91                         disable_revocation_policy_check,
  92                         available: Arc::new(Mutex::new(true)),
  93                 }
  94         }
  95
  96         pub fn channel_type_features(&self) -> &ChannelTypeFeatures { self.inner.channel_type_features().unwrap() }
  97
  98         #[cfg(test)]
  99         pub fn get_enforcement_state(&self) -> MutexGuard<EnforcementState> {
 100                 self.state.lock().unwrap()
 101         }
 102
 103         /// Marks the signer's availability.
 104         ///
 105         /// When `true`, methods are forwarded to the underlying signer as normal. When `false`, some
 106         /// methods will return `Err` indicating that the signer is unavailable. Intended to be used for
 107         /// testing asynchronous signing.
 108         #[cfg(test)]
 109         pub fn set_available(&self, available: bool) {
 110                 *self.available.lock().unwrap() = available;
 111         }
 112 }
 113
 114 impl ChannelSigner for TestChannelSigner {
 115         fn get_per_commitment_point(&self, idx: u64, secp_ctx: &Secp256k1<secp256k1::All>) -> PublicKey {
 116                 self.inner.get_per_commitment_point(idx, secp_ctx)
 117         }
 118
 119         fn release_commitment_secret(&self, idx: u64) -> [u8; 32] {
 120                 {
 121                         let mut state = self.state.lock().unwrap();
 122                         assert!(idx == state.last_holder_revoked_commitment || idx == state.last_holder_revoked_commitment - 1, "can only revoke the current or next unrevoked commitment - trying {}, last revoked {}", idx, state.last_holder_revoked_commitment);
 123                         assert!(idx > state.last_holder_commitment, "cannot revoke the last holder commitment - attempted to revoke {} last commitment {}", idx, state.last_holder_commitment);
 124                         state.last_holder_revoked_commitment = idx;
 125                 }
 126                 self.inner.release_commitment_secret(idx)
 127         }
 128
 129         fn validate_holder_commitment(&self, holder_tx: &HolderCommitmentTransaction, _preimages: Vec<PaymentPreimage>) -> Result<(), ()> {
 130                 let mut state = self.state.lock().unwrap();
 131                 let idx = holder_tx.commitment_number();
 132                 assert!(idx == state.last_holder_commitment || idx == state.last_holder_commitment - 1, "expecting to validate the current or next holder commitment - trying {}, current {}", idx, state.last_holder_commitment);
 133                 state.last_holder_commitment = idx;
 134                 Ok(())
 135         }
 136
 137         fn pubkeys(&self) -> &ChannelPublicKeys { self.inner.pubkeys() }
 138
 139         fn channel_keys_id(&self) -> [u8; 32] { self.inner.channel_keys_id() }
 140
 141         fn provide_channel_parameters(&mut self, channel_parameters: &ChannelTransactionParameters) {
 142                 self.inner.provide_channel_parameters(channel_parameters)
 143         }
 144 }
 145
 146 impl EcdsaChannelSigner for TestChannelSigner {
 147         fn sign_counterparty_commitment(&self, commitment_tx: &CommitmentTransaction, preimages: Vec<PaymentPreimage>, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<(Signature, Vec<Signature>), ()> {
 148                 self.verify_counterparty_commitment_tx(commitment_tx, secp_ctx);
 149
 150                 {
 151                         if !*self.available.lock().unwrap() {
 152                                 return Err(());
 153                         }
 154                         let mut state = self.state.lock().unwrap();
 155                         let actual_commitment_number = commitment_tx.commitment_number();
 156                         let last_commitment_number = state.last_counterparty_commitment;
 157                         // These commitment numbers are backwards counting.  We expect either the same as the previously encountered,
 158                         // or the next one.
 159                         assert!(last_commitment_number == actual_commitment_number || last_commitment_number - 1 == actual_commitment_number, "{} doesn't come after {}", actual_commitment_number, last_commitment_number);
 160                         // Ensure that the counterparty doesn't get more than two broadcastable commitments -
 161                         // the last and the one we are trying to sign
 162                         assert!(actual_commitment_number >= state.last_counterparty_revoked_commitment - 2, "cannot sign a commitment if second to last wasn't revoked - signing {} revoked {}", actual_commitment_number, state.last_counterparty_revoked_commitment);
 163                         state.last_counterparty_commitment = cmp::min(last_commitment_number, actual_commitment_number)
 164                 }
 165
 166                 Ok(self.inner.sign_counterparty_commitment(commitment_tx, preimages, secp_ctx).unwrap())
 167         }
 168
 169         fn validate_counterparty_revocation(&self, idx: u64, _secret: &SecretKey) -> Result<(), ()> {
 170                 if !*self.available.lock().unwrap() {
 171                         return Err(());
 172                 }
 173                 let mut state = self.state.lock().unwrap();
 174                 assert!(idx == state.last_counterparty_revoked_commitment || idx == state.last_counterparty_revoked_commitment - 1, "expecting to validate the current or next counterparty revocation - trying {}, current {}", idx, state.last_counterparty_revoked_commitment);
 175                 state.last_counterparty_revoked_commitment = idx;
 176                 Ok(())
 177         }
 178
 179         fn sign_holder_commitment(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
 180                 if !*self.available.lock().unwrap() {
 181                         return Err(());
 182                 }
 183                 let trusted_tx = self.verify_holder_commitment_tx(commitment_tx, secp_ctx);
 184                 let state = self.state.lock().unwrap();
 185                 let commitment_number = trusted_tx.commitment_number();
 186                 if state.last_holder_revoked_commitment - 1 != commitment_number && state.last_holder_revoked_commitment - 2 != commitment_number {
 187                         if !self.disable_revocation_policy_check {
 188                                 panic!("can only sign the next two unrevoked commitment numbers, revoked={} vs requested={} for {}",
 189                                        state.last_holder_revoked_commitment, commitment_number, self.inner.commitment_seed[0])
 190                         }
 191                 }
 192                 Ok(self.inner.sign_holder_commitment(commitment_tx, secp_ctx).unwrap())
 193         }
 194
 195         #[cfg(any(test,feature = "unsafe_revoked_tx_signing"))]
 196         fn unsafe_sign_holder_commitment(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
 197                 Ok(self.inner.unsafe_sign_holder_commitment(commitment_tx, secp_ctx).unwrap())
 198         }
 199
 200         fn sign_justice_revoked_output(&self, justice_tx: &Transaction, input: usize, amount: u64, per_commitment_key: &SecretKey, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
 201                 Ok(self.inner.sign_justice_revoked_output(justice_tx, input, amount, per_commitment_key, secp_ctx).unwrap())
 202         }
 203
 204         fn sign_justice_revoked_htlc(&self, justice_tx: &Transaction, input: usize, amount: u64, per_commitment_key: &SecretKey, htlc: &HTLCOutputInCommitment, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
 205                 Ok(self.inner.sign_justice_revoked_htlc(justice_tx, input, amount, per_commitment_key, htlc, secp_ctx).unwrap())
 206         }
 207
 208         fn sign_holder_htlc_transaction(
 209                 &self, htlc_tx: &Transaction, input: usize, htlc_descriptor: &HTLCDescriptor,
 210                 secp_ctx: &Secp256k1<secp256k1::All>
 211         ) -> Result<Signature, ()> {
 212                 let state = self.state.lock().unwrap();
 213                 if state.last_holder_revoked_commitment - 1 != htlc_descriptor.per_commitment_number &&
 214                         state.last_holder_revoked_commitment - 2 != htlc_descriptor.per_commitment_number
 215                 {
 216                         if !self.disable_revocation_policy_check {
 217                                 panic!("can only sign the next two unrevoked commitment numbers, revoked={} vs requested={} for {}",
 218                                        state.last_holder_revoked_commitment, htlc_descriptor.per_commitment_number, self.inner.commitment_seed[0])
 219                         }
 220                 }
 221                 assert_eq!(htlc_tx.input[input], htlc_descriptor.unsigned_tx_input());
 222                 assert_eq!(htlc_tx.output[input], htlc_descriptor.tx_output(secp_ctx));
 223                 {
 224                         let witness_script = htlc_descriptor.witness_script(secp_ctx);
 225                         let sighash_type = if self.channel_type_features().supports_anchors_zero_fee_htlc_tx() {
 226                                 EcdsaSighashType::SinglePlusAnyoneCanPay
 227                         } else {
 228                                 EcdsaSighashType::All
 229                         };
 230                         let sighash = &sighash::SighashCache::new(&*htlc_tx).segwit_signature_hash(
 231                                 input, &witness_script, htlc_descriptor.htlc.amount_msat / 1000, sighash_type
 232                         ).unwrap();
 233                         let countersignatory_htlc_key = chan_utils::derive_public_key(
 234                                 &secp_ctx, &htlc_descriptor.per_commitment_point, &self.inner.counterparty_pubkeys().unwrap().htlc_basepoint
 235                         );
 236                         secp_ctx.verify_ecdsa(
 237                                 &hash_to_message!(&sighash), &htlc_descriptor.counterparty_sig, &countersignatory_htlc_key
 238                         ).unwrap();
 239                 }
 240                 Ok(self.inner.sign_holder_htlc_transaction(htlc_tx, input, htlc_descriptor, secp_ctx).unwrap())
 241         }
 242
 243         fn sign_counterparty_htlc_transaction(&self, htlc_tx: &Transaction, input: usize, amount: u64, per_commitment_point: &PublicKey, htlc: &HTLCOutputInCommitment, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
 244                 Ok(self.inner.sign_counterparty_htlc_transaction(htlc_tx, input, amount, per_commitment_point, htlc, secp_ctx).unwrap())
 245         }
 246
 247         fn sign_closing_transaction(&self, closing_tx: &ClosingTransaction, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
 248                 closing_tx.verify(self.inner.funding_outpoint().unwrap().into_bitcoin_outpoint())
 249                         .expect("derived different closing transaction");
 250                 Ok(self.inner.sign_closing_transaction(closing_tx, secp_ctx).unwrap())
 251         }
 252
 253         fn sign_holder_anchor_input(
 254                 &self, anchor_tx: &Transaction, input: usize, secp_ctx: &Secp256k1<secp256k1::All>,
 255         ) -> Result<Signature, ()> {
 256                 debug_assert!(MIN_CHAN_DUST_LIMIT_SATOSHIS > ANCHOR_OUTPUT_VALUE_SATOSHI);
 257                 // As long as our minimum dust limit is enforced and is greater than our anchor output
 258                 // value, an anchor output can only have an index within [0, 1].
 259                 assert!(anchor_tx.input[input].previous_output.vout == 0 || anchor_tx.input[input].previous_output.vout == 1);
 260                 self.inner.sign_holder_anchor_input(anchor_tx, input, secp_ctx)
 261         }
 262
 263         fn sign_channel_announcement_with_funding_key(
 264                 &self, msg: &msgs::UnsignedChannelAnnouncement, secp_ctx: &Secp256k1<secp256k1::All>
 265         ) -> Result<Signature, ()> {
 266                 self.inner.sign_channel_announcement_with_funding_key(msg, secp_ctx)
 267         }
 268 }
 269
 270 impl WriteableEcdsaChannelSigner for TestChannelSigner {}
 271
 272 impl Writeable for TestChannelSigner {
 273         fn write<W: Writer>(&self, writer: &mut W) -> Result<(), Error> {
 274                 // TestChannelSigner has two fields - `inner` ([`InMemorySigner`]) and `state`
 275                 // ([`EnforcementState`]). `inner` is serialized here and deserialized by
 276                 // [`SignerProvider::read_chan_signer`]. `state` is managed by [`SignerProvider`]
 277                 // and will be serialized as needed by the implementation of that trait.
 278                 self.inner.write(writer)?;
 279                 Ok(())
 280         }
 281 }
 282
 283 impl TestChannelSigner {
 284         fn verify_counterparty_commitment_tx<'a, T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &'a CommitmentTransaction, secp_ctx: &Secp256k1<T>) -> TrustedCommitmentTransaction<'a> {
 285                 commitment_tx.verify(
 286                         &self.inner.get_channel_parameters().unwrap().as_counterparty_broadcastable(),
 287                         self.inner.counterparty_pubkeys().unwrap(), self.inner.pubkeys(), secp_ctx
 288                 ).expect("derived different per-tx keys or built transaction")
 289         }
 290
 291         fn verify_holder_commitment_tx<'a, T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &'a CommitmentTransaction, secp_ctx: &Secp256k1<T>) -> TrustedCommitmentTransaction<'a> {
 292                 commitment_tx.verify(
 293                         &self.inner.get_channel_parameters().unwrap().as_holder_broadcastable(),
 294                         self.inner.pubkeys(), self.inner.counterparty_pubkeys().unwrap(), secp_ctx
 295                 ).expect("derived different per-tx keys or built transaction")
 296         }
 297 }
 298
 299 /// The state used by [`TestChannelSigner`] in order to enforce policy checks
 300 ///
 301 /// This structure is maintained by KeysInterface since we may have multiple copies of
 302 /// the signer and they must coordinate their state.
 303 #[derive(Clone)]
 304 pub struct EnforcementState {
 305         /// The last counterparty commitment number we signed, backwards counting
 306         pub last_counterparty_commitment: u64,
 307         /// The last counterparty commitment they revoked, backwards counting
 308         pub last_counterparty_revoked_commitment: u64,
 309         /// The last holder commitment number we revoked, backwards counting
 310         pub last_holder_revoked_commitment: u64,
 311         /// The last validated holder commitment number, backwards counting
 312         pub last_holder_commitment: u64,
 313 }
 314
 315 impl EnforcementState {
 316         /// Enforcement state for a new channel
 317         pub fn new() -> Self {
 318                 EnforcementState {
 319                         last_counterparty_commitment: INITIAL_REVOKED_COMMITMENT_NUMBER,
 320                         last_counterparty_revoked_commitment: INITIAL_REVOKED_COMMITMENT_NUMBER,
 321                         last_holder_revoked_commitment: INITIAL_REVOKED_COMMITMENT_NUMBER,
 322                         last_holder_commitment: INITIAL_REVOKED_COMMITMENT_NUMBER,
 323                 }
 324         }
 325 }