_ 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::channel_keys::{HtlcKey};
  13 use crate::ln::{msgs, PaymentPreimage};
  14 use crate::sign::{WriteableEcdsaChannelSigner, InMemorySigner, ChannelSigner, EcdsaChannelSigner};
  15
  16 use crate::prelude::*;
  17 use core::cmp;
  18 use crate::sync::{Mutex, Arc};
  19 #[cfg(test)] use crate::sync::MutexGuard;
  20
  21 use bitcoin::blockdata::transaction::Transaction;
  22 use bitcoin::hashes::Hash;
  23 use bitcoin::sighash;
  24 use bitcoin::sighash::EcdsaSighashType;
  25
  26 use bitcoin::secp256k1;
  27 use bitcoin::secp256k1::{SecretKey, PublicKey};
  28 use bitcoin::secp256k1::{Secp256k1, ecdsa::Signature};
  29 use crate::sign::HTLCDescriptor;
  30 use crate::util::ser::{Writeable, Writer};
  31 use crate::io::Error;
  32 use crate::ln::features::ChannelTypeFeatures;
  33
  34 /// Initial value for revoked commitment downward counter
  35 pub const INITIAL_REVOKED_COMMITMENT_NUMBER: u64 = 1 << 48;
  36
  37 /// An implementation of Sign that enforces some policy checks.  The current checks
  38 /// are an incomplete set.  They include:
  39 ///
  40 /// - When signing, the holder transaction has not been revoked
  41 /// - When revoking, the holder transaction has not been signed
  42 /// - The holder commitment number is monotonic and without gaps
  43 /// - The revoked holder commitment number is monotonic and without gaps
  44 /// - There is at least one unrevoked holder transaction at all times
  45 /// - The counterparty commitment number is monotonic and without gaps
  46 /// - The pre-derived keys and pre-built transaction in CommitmentTransaction were correctly built
  47 ///
  48 /// Eventually we will probably want to expose a variant of this which would essentially
  49 /// be what you'd want to run on a hardware wallet.
  50 ///
  51 /// Note that counterparty signatures on the holder transaction are not checked, but it should
  52 /// be in a complete implementation.
  53 ///
  54 /// Note that before we do so we should ensure its serialization format has backwards- and
  55 /// forwards-compatibility prefix/suffixes!
  56 #[derive(Clone)]
  57 pub struct TestChannelSigner {
  58         pub inner: InMemorySigner,
  59         /// Channel state used for policy enforcement
  60         pub state: Arc<Mutex<EnforcementState>>,
  61         pub disable_revocation_policy_check: bool,
  62         /// When `true` (the default), the signer will respond immediately with signatures. When `false`,
  63         /// the signer will return an error indicating that it is unavailable.
  64         pub available: Arc<Mutex<bool>>,
  65 }
  66
  67 impl PartialEq for TestChannelSigner {
  68         fn eq(&self, o: &Self) -> bool {
  69                 Arc::ptr_eq(&self.state, &o.state)
  70         }
  71 }
  72
  73 impl TestChannelSigner {
  74         /// Construct an TestChannelSigner
  75         pub fn new(inner: InMemorySigner) -> Self {
  76                 let state = Arc::new(Mutex::new(EnforcementState::new()));
  77                 Self {
  78                         inner,
  79                         state,
  80                         disable_revocation_policy_check: false,
  81                         available: Arc::new(Mutex::new(true)),
  82                 }
  83         }
  84
  85         /// Construct an TestChannelSigner with externally managed storage
  86         ///
  87         /// Since there are multiple copies of this struct for each channel, some coordination is needed
  88         /// so that all copies are aware of enforcement state.  A pointer to this state is provided
  89         /// here, usually by an implementation of KeysInterface.
  90         pub fn new_with_revoked(inner: InMemorySigner, state: Arc<Mutex<EnforcementState>>, disable_revocation_policy_check: bool) -> Self {
  91                 Self {
  92                         inner,
  93                         state,
  94                         disable_revocation_policy_check,
  95                         available: Arc::new(Mutex::new(true)),
  96                 }
  97         }
  98
  99         pub fn channel_type_features(&self) -> &ChannelTypeFeatures { self.inner.channel_type_features().unwrap() }
 100
 101         #[cfg(test)]
 102         pub fn get_enforcement_state(&self) -> MutexGuard<EnforcementState> {
 103                 self.state.lock().unwrap()
 104         }
 105
 106         /// Marks the signer's availability.
 107         ///
 108         /// When `true`, methods are forwarded to the underlying signer as normal. When `false`, some
 109         /// methods will return `Err` indicating that the signer is unavailable. Intended to be used for
 110         /// testing asynchronous signing.
 111         #[cfg(test)]
 112         pub fn set_available(&self, available: bool) {
 113                 *self.available.lock().unwrap() = available;
 114         }
 115 }
 116
 117 impl ChannelSigner for TestChannelSigner {
 118         fn get_per_commitment_point(&self, idx: u64, secp_ctx: &Secp256k1<secp256k1::All>) -> PublicKey {
 119                 self.inner.get_per_commitment_point(idx, secp_ctx)
 120         }
 121
 122         fn release_commitment_secret(&self, idx: u64) -> [u8; 32] {
 123                 {
 124                         let mut state = self.state.lock().unwrap();
 125                         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);
 126                         assert!(idx > state.last_holder_commitment, "cannot revoke the last holder commitment - attempted to revoke {} last commitment {}", idx, state.last_holder_commitment);
 127                         state.last_holder_revoked_commitment = idx;
 128                 }
 129                 self.inner.release_commitment_secret(idx)
 130         }
 131
 132         fn validate_holder_commitment(&self, holder_tx: &HolderCommitmentTransaction, _preimages: Vec<PaymentPreimage>) -> Result<(), ()> {
 133                 let mut state = self.state.lock().unwrap();
 134                 let idx = holder_tx.commitment_number();
 135                 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);
 136                 state.last_holder_commitment = idx;
 137                 Ok(())
 138         }
 139
 140         fn pubkeys(&self) -> &ChannelPublicKeys { self.inner.pubkeys() }
 141
 142         fn channel_keys_id(&self) -> [u8; 32] { self.inner.channel_keys_id() }
 143
 144         fn provide_channel_parameters(&mut self, channel_parameters: &ChannelTransactionParameters) {
 145                 self.inner.provide_channel_parameters(channel_parameters)
 146         }
 147 }
 148
 149 impl EcdsaChannelSigner for TestChannelSigner {
 150         fn sign_counterparty_commitment(&self, commitment_tx: &CommitmentTransaction, preimages: Vec<PaymentPreimage>, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<(Signature, Vec<Signature>), ()> {
 151                 self.verify_counterparty_commitment_tx(commitment_tx, secp_ctx);
 152
 153                 {
 154                         if !*self.available.lock().unwrap() {
 155                                 return Err(());
 156                         }
 157                         let mut state = self.state.lock().unwrap();
 158                         let actual_commitment_number = commitment_tx.commitment_number();
 159                         let last_commitment_number = state.last_counterparty_commitment;
 160                         // These commitment numbers are backwards counting.  We expect either the same as the previously encountered,
 161                         // or the next one.
 162                         assert!(last_commitment_number == actual_commitment_number || last_commitment_number - 1 == actual_commitment_number, "{} doesn't come after {}", actual_commitment_number, last_commitment_number);
 163                         // Ensure that the counterparty doesn't get more than two broadcastable commitments -
 164                         // the last and the one we are trying to sign
 165                         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);
 166                         state.last_counterparty_commitment = cmp::min(last_commitment_number, actual_commitment_number)
 167                 }
 168
 169                 Ok(self.inner.sign_counterparty_commitment(commitment_tx, preimages, secp_ctx).unwrap())
 170         }
 171
 172         fn validate_counterparty_revocation(&self, idx: u64, _secret: &SecretKey) -> Result<(), ()> {
 173                 if !*self.available.lock().unwrap() {
 174                         return Err(());
 175                 }
 176                 let mut state = self.state.lock().unwrap();
 177                 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);
 178                 state.last_counterparty_revoked_commitment = idx;
 179                 Ok(())
 180         }
 181
 182         fn sign_holder_commitment(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
 183                 if !*self.available.lock().unwrap() {
 184                         return Err(());
 185                 }
 186                 let trusted_tx = self.verify_holder_commitment_tx(commitment_tx, secp_ctx);
 187                 let state = self.state.lock().unwrap();
 188                 let commitment_number = trusted_tx.commitment_number();
 189                 if state.last_holder_revoked_commitment - 1 != commitment_number && state.last_holder_revoked_commitment - 2 != commitment_number {
 190                         if !self.disable_revocation_policy_check {
 191                                 panic!("can only sign the next two unrevoked commitment numbers, revoked={} vs requested={} for {}",
 192                                        state.last_holder_revoked_commitment, commitment_number, self.inner.commitment_seed[0])
 193                         }
 194                 }
 195                 Ok(self.inner.sign_holder_commitment(commitment_tx, secp_ctx).unwrap())
 196         }
 197
 198         #[cfg(any(test,feature = "unsafe_revoked_tx_signing"))]
 199         fn unsafe_sign_holder_commitment(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
 200                 Ok(self.inner.unsafe_sign_holder_commitment(commitment_tx, secp_ctx).unwrap())
 201         }
 202
 203         fn sign_justice_revoked_output(&self, justice_tx: &Transaction, input: usize, amount: u64, per_commitment_key: &SecretKey, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
 204                 Ok(self.inner.sign_justice_revoked_output(justice_tx, input, amount, per_commitment_key, secp_ctx).unwrap())
 205         }
 206
 207         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, ()> {
 208                 Ok(self.inner.sign_justice_revoked_htlc(justice_tx, input, amount, per_commitment_key, htlc, secp_ctx).unwrap())
 209         }
 210
 211         fn sign_holder_htlc_transaction(
 212                 &self, htlc_tx: &Transaction, input: usize, htlc_descriptor: &HTLCDescriptor,
 213                 secp_ctx: &Secp256k1<secp256k1::All>
 214         ) -> Result<Signature, ()> {
 215                 let state = self.state.lock().unwrap();
 216                 if state.last_holder_revoked_commitment - 1 != htlc_descriptor.per_commitment_number &&
 217                         state.last_holder_revoked_commitment - 2 != htlc_descriptor.per_commitment_number
 218                 {
 219                         if !self.disable_revocation_policy_check {
 220                                 panic!("can only sign the next two unrevoked commitment numbers, revoked={} vs requested={} for {}",
 221                                        state.last_holder_revoked_commitment, htlc_descriptor.per_commitment_number, self.inner.commitment_seed[0])
 222                         }
 223                 }
 224                 assert_eq!(htlc_tx.input[input], htlc_descriptor.unsigned_tx_input());
 225                 assert_eq!(htlc_tx.output[input], htlc_descriptor.tx_output(secp_ctx));
 226                 {
 227                         let witness_script = htlc_descriptor.witness_script(secp_ctx);
 228                         let sighash_type = if self.channel_type_features().supports_anchors_zero_fee_htlc_tx() {
 229                                 EcdsaSighashType::SinglePlusAnyoneCanPay
 230                         } else {
 231                                 EcdsaSighashType::All
 232                         };
 233                         let sighash = &sighash::SighashCache::new(&*htlc_tx).segwit_signature_hash(
 234                                 input, &witness_script, htlc_descriptor.htlc.amount_msat / 1000, sighash_type
 235                         ).unwrap();
 236                         let countersignatory_htlc_key = HtlcKey::from_basepoint(
 237                                 &secp_ctx, &self.inner.counterparty_pubkeys().unwrap().htlc_basepoint, &htlc_descriptor.per_commitment_point,
 238                         );
 239
 240                         secp_ctx.verify_ecdsa(
 241                                 &hash_to_message!(sighash.as_byte_array()), &htlc_descriptor.counterparty_sig, &countersignatory_htlc_key.to_public_key()
 242                         ).unwrap();
 243                 }
 244                 Ok(self.inner.sign_holder_htlc_transaction(htlc_tx, input, htlc_descriptor, secp_ctx).unwrap())
 245         }
 246
 247         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, ()> {
 248                 Ok(self.inner.sign_counterparty_htlc_transaction(htlc_tx, input, amount, per_commitment_point, htlc, secp_ctx).unwrap())
 249         }
 250
 251         fn sign_closing_transaction(&self, closing_tx: &ClosingTransaction, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
 252                 closing_tx.verify(self.inner.funding_outpoint().unwrap().into_bitcoin_outpoint())
 253                         .expect("derived different closing transaction");
 254                 Ok(self.inner.sign_closing_transaction(closing_tx, secp_ctx).unwrap())
 255         }
 256
 257         fn sign_holder_anchor_input(
 258                 &self, anchor_tx: &Transaction, input: usize, secp_ctx: &Secp256k1<secp256k1::All>,
 259         ) -> Result<Signature, ()> {
 260                 debug_assert!(MIN_CHAN_DUST_LIMIT_SATOSHIS > ANCHOR_OUTPUT_VALUE_SATOSHI);
 261                 // As long as our minimum dust limit is enforced and is greater than our anchor output
 262                 // value, an anchor output can only have an index within [0, 1].
 263                 assert!(anchor_tx.input[input].previous_output.vout == 0 || anchor_tx.input[input].previous_output.vout == 1);
 264                 self.inner.sign_holder_anchor_input(anchor_tx, input, secp_ctx)
 265         }
 266
 267         fn sign_channel_announcement_with_funding_key(
 268                 &self, msg: &msgs::UnsignedChannelAnnouncement, secp_ctx: &Secp256k1<secp256k1::All>
 269         ) -> Result<Signature, ()> {
 270                 self.inner.sign_channel_announcement_with_funding_key(msg, secp_ctx)
 271         }
 272 }
 273
 274 impl WriteableEcdsaChannelSigner for TestChannelSigner {}
 275
 276 impl Writeable for TestChannelSigner {
 277         fn write<W: Writer>(&self, writer: &mut W) -> Result<(), Error> {
 278                 // TestChannelSigner has two fields - `inner` ([`InMemorySigner`]) and `state`
 279                 // ([`EnforcementState`]). `inner` is serialized here and deserialized by
 280                 // [`SignerProvider::read_chan_signer`]. `state` is managed by [`SignerProvider`]
 281                 // and will be serialized as needed by the implementation of that trait.
 282                 self.inner.write(writer)?;
 283                 Ok(())
 284         }
 285 }
 286
 287 impl TestChannelSigner {
 288         fn verify_counterparty_commitment_tx<'a, T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &'a CommitmentTransaction, secp_ctx: &Secp256k1<T>) -> TrustedCommitmentTransaction<'a> {
 289                 commitment_tx.verify(
 290                         &self.inner.get_channel_parameters().unwrap().as_counterparty_broadcastable(),
 291                         self.inner.counterparty_pubkeys().unwrap(), self.inner.pubkeys(), secp_ctx
 292                 ).expect("derived different per-tx keys or built transaction")
 293         }
 294
 295         fn verify_holder_commitment_tx<'a, T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &'a CommitmentTransaction, secp_ctx: &Secp256k1<T>) -> TrustedCommitmentTransaction<'a> {
 296                 commitment_tx.verify(
 297                         &self.inner.get_channel_parameters().unwrap().as_holder_broadcastable(),
 298                         self.inner.pubkeys(), self.inner.counterparty_pubkeys().unwrap(), secp_ctx
 299                 ).expect("derived different per-tx keys or built transaction")
 300         }
 301 }
 302
 303 /// The state used by [`TestChannelSigner`] in order to enforce policy checks
 304 ///
 305 /// This structure is maintained by KeysInterface since we may have multiple copies of
 306 /// the signer and they must coordinate their state.
 307 #[derive(Clone)]
 308 pub struct EnforcementState {
 309         /// The last counterparty commitment number we signed, backwards counting
 310         pub last_counterparty_commitment: u64,
 311         /// The last counterparty commitment they revoked, backwards counting
 312         pub last_counterparty_revoked_commitment: u64,
 313         /// The last holder commitment number we revoked, backwards counting
 314         pub last_holder_revoked_commitment: u64,
 315         /// The last validated holder commitment number, backwards counting
 316         pub last_holder_commitment: u64,
 317 }
 318
 319 impl EnforcementState {
 320         /// Enforcement state for a new channel
 321         pub fn new() -> Self {
 322                 EnforcementState {
 323                         last_counterparty_commitment: INITIAL_REVOKED_COMMITMENT_NUMBER,
 324                         last_counterparty_revoked_commitment: INITIAL_REVOKED_COMMITMENT_NUMBER,
 325                         last_holder_revoked_commitment: INITIAL_REVOKED_COMMITMENT_NUMBER,
 326                         last_holder_commitment: INITIAL_REVOKED_COMMITMENT_NUMBER,
 327                 }
 328         }
 329 }