use prelude::*;
use core::cmp;
use sync::{Mutex, Arc};
+#[cfg(test)] use sync::MutexGuard;
use bitcoin::blockdata::transaction::{Transaction, SigHashType};
use bitcoin::util::bip143;
/// - When signing, the holder transaction has not been revoked
/// - When revoking, the holder transaction has not been signed
/// - The holder commitment number is monotonic and without gaps
+/// - The revoked holder commitment number is monotonic and without gaps
+/// - There is at least one unrevoked holder transaction at all times
/// - The counterparty commitment number is monotonic and without gaps
/// - The pre-derived keys and pre-built transaction in CommitmentTransaction were correctly built
///
/// Eventually we will probably want to expose a variant of this which would essentially
/// be what you'd want to run on a hardware wallet.
///
+/// Note that counterparty signatures on the holder transaction are not checked, but it should
+/// be in a complete implementation.
+///
/// Note that before we do so we should ensure its serialization format has backwards- and
/// forwards-compatibility prefix/suffixes!
#[derive(Clone)]
pub struct EnforcingSigner {
pub inner: InMemorySigner,
- /// The last counterparty commitment number we signed, backwards counting
- pub last_commitment_number: Arc<Mutex<Option<u64>>>,
- /// The last holder commitment number we revoked, backwards counting
- pub revoked_commitment: Arc<Mutex<u64>>,
+ /// Channel state used for policy enforcement
+ pub state: Arc<Mutex<EnforcementState>>,
pub disable_revocation_policy_check: bool,
}
impl EnforcingSigner {
/// Construct an EnforcingSigner
pub fn new(inner: InMemorySigner) -> Self {
+ let state = Arc::new(Mutex::new(EnforcementState::new()));
Self {
inner,
- last_commitment_number: Arc::new(Mutex::new(None)),
- revoked_commitment: Arc::new(Mutex::new(INITIAL_REVOKED_COMMITMENT_NUMBER)),
+ state,
disable_revocation_policy_check: false
}
}
/// Construct an EnforcingSigner with externally managed storage
///
/// Since there are multiple copies of this struct for each channel, some coordination is needed
- /// so that all copies are aware of revocations. A pointer to this state is provided here, usually
- /// by an implementation of KeysInterface.
- pub fn new_with_revoked(inner: InMemorySigner, revoked_commitment: Arc<Mutex<u64>>, disable_revocation_policy_check: bool) -> Self {
+ /// so that all copies are aware of enforcement state. A pointer to this state is provided
+ /// here, usually by an implementation of KeysInterface.
+ pub fn new_with_revoked(inner: InMemorySigner, state: Arc<Mutex<EnforcementState>>, disable_revocation_policy_check: bool) -> Self {
Self {
inner,
- last_commitment_number: Arc::new(Mutex::new(None)),
- revoked_commitment,
+ state,
disable_revocation_policy_check
}
}
+
+ #[cfg(test)]
+ pub fn get_enforcement_state(&self) -> MutexGuard<EnforcementState> {
+ self.state.lock().unwrap()
+ }
}
impl BaseSign for EnforcingSigner {
fn release_commitment_secret(&self, idx: u64) -> [u8; 32] {
{
- let mut revoked = self.revoked_commitment.lock().unwrap();
- assert!(idx == *revoked || idx == *revoked - 1, "can only revoke the current or next unrevoked commitment - trying {}, revoked {}", idx, *revoked);
- *revoked = idx;
+ let mut state = self.state.lock().unwrap();
+ 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);
+ assert!(idx > state.last_holder_commitment, "cannot revoke the last holder commitment - attempted to revoke {} last commitment {}", idx, state.last_holder_commitment);
+ state.last_holder_revoked_commitment = idx;
}
self.inner.release_commitment_secret(idx)
}
+ fn validate_holder_commitment(&self, holder_tx: &HolderCommitmentTransaction) {
+ let mut state = self.state.lock().unwrap();
+ let idx = holder_tx.commitment_number();
+ 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);
+ state.last_holder_commitment = idx;
+ }
+
fn pubkeys(&self) -> &ChannelPublicKeys { self.inner.pubkeys() }
fn channel_keys_id(&self) -> [u8; 32] { self.inner.channel_keys_id() }
self.verify_counterparty_commitment_tx(commitment_tx, secp_ctx);
{
- let mut last_commitment_number_guard = self.last_commitment_number.lock().unwrap();
+ let mut state = self.state.lock().unwrap();
let actual_commitment_number = commitment_tx.commitment_number();
- let last_commitment_number = last_commitment_number_guard.unwrap_or(actual_commitment_number);
+ let last_commitment_number = state.last_counterparty_commitment;
// These commitment numbers are backwards counting. We expect either the same as the previously encountered,
// or the next one.
assert!(last_commitment_number == actual_commitment_number || last_commitment_number - 1 == actual_commitment_number, "{} doesn't come after {}", actual_commitment_number, last_commitment_number);
- *last_commitment_number_guard = Some(cmp::min(last_commitment_number, actual_commitment_number))
+ // Ensure that the counterparty doesn't get more than two broadcastable commitments -
+ // the last and the one we are trying to sign
+ 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);
+ state.last_counterparty_commitment = cmp::min(last_commitment_number, actual_commitment_number)
}
Ok(self.inner.sign_counterparty_commitment(commitment_tx, secp_ctx).unwrap())
}
+ fn validate_counterparty_revocation(&self, idx: u64, _secret: &SecretKey) {
+ let mut state = self.state.lock().unwrap();
+ 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);
+ state.last_counterparty_revoked_commitment = idx;
+ }
+
fn sign_holder_commitment_and_htlcs(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<(Signature, Vec<Signature>), ()> {
let trusted_tx = self.verify_holder_commitment_tx(commitment_tx, secp_ctx);
let commitment_txid = trusted_tx.txid();
let holder_csv = self.inner.counterparty_selected_contest_delay();
- let revoked = self.revoked_commitment.lock().unwrap();
+ let state = self.state.lock().unwrap();
let commitment_number = trusted_tx.commitment_number();
- if *revoked - 1 != commitment_number && *revoked - 2 != commitment_number {
+ if state.last_holder_revoked_commitment - 1 != commitment_number && state.last_holder_revoked_commitment - 2 != commitment_number {
if !self.disable_revocation_policy_check {
panic!("can only sign the next two unrevoked commitment numbers, revoked={} vs requested={} for {}",
- *revoked, commitment_number, self.inner.commitment_seed[0])
+ state.last_holder_revoked_commitment, commitment_number, self.inner.commitment_seed[0])
}
}
impl Writeable for EnforcingSigner {
fn write<W: Writer>(&self, writer: &mut W) -> Result<(), Error> {
self.inner.write(writer)?;
- let last = *self.last_commitment_number.lock().unwrap();
- last.write(writer)?;
+ // NOTE - the commitment state is maintained by KeysInterface, so we don't persist it
Ok(())
}
}
impl Readable for EnforcingSigner {
fn read<R: io::Read>(reader: &mut R) -> Result<Self, DecodeError> {
let inner = Readable::read(reader)?;
- let last_commitment_number = Readable::read(reader)?;
+ let state = Arc::new(Mutex::new(EnforcementState::new()));
Ok(EnforcingSigner {
inner,
- last_commitment_number: Arc::new(Mutex::new(last_commitment_number)),
- revoked_commitment: Arc::new(Mutex::new(INITIAL_REVOKED_COMMITMENT_NUMBER)),
+ state,
disable_revocation_policy_check: false,
})
}
.expect("derived different per-tx keys or built transaction")
}
}
+
+/// The state used by [`EnforcingSigner`] in order to enforce policy checks
+///
+/// This structure is maintained by KeysInterface since we may have multiple copies of
+/// the signer and they must coordinate their state.
+#[derive(Clone)]
+pub struct EnforcementState {
+ /// The last counterparty commitment number we signed, backwards counting
+ pub last_counterparty_commitment: u64,
+ /// The last counterparty commitment they revoked, backwards counting
+ pub last_counterparty_revoked_commitment: u64,
+ /// The last holder commitment number we revoked, backwards counting
+ pub last_holder_revoked_commitment: u64,
+ /// The last validated holder commitment number, backwards counting
+ pub last_holder_commitment: u64,
+}
+
+impl EnforcementState {
+ /// Enforcement state for a new channel
+ pub fn new() -> Self {
+ EnforcementState {
+ last_counterparty_commitment: INITIAL_REVOKED_COMMITMENT_NUMBER,
+ last_counterparty_revoked_commitment: INITIAL_REVOKED_COMMITMENT_NUMBER,
+ last_holder_revoked_commitment: INITIAL_REVOKED_COMMITMENT_NUMBER,
+ last_holder_commitment: INITIAL_REVOKED_COMMITMENT_NUMBER,
+ }
+ }
+}
projects / rust-lightning / blobdiff