Merge pull request #404 from TheBlueMatt/2019-11-signer-api

[rust-lightning] / lightning / src / util / enforcing_trait_impls.rs

diff --git a/lightning/src/util/enforcing_trait_impls.rs b/lightning/src/util/enforcing_trait_impls.rs
new file mode 100644 (file)
index 0000000..09d7017
--- /dev/null
+++ b/lightning/src/util/enforcing_trait_impls.rs
@@ -0,0 +1,58 @@
+use ln::chan_utils::{HTLCOutputInCommitment, TxCreationKeys};
+use chain::keysinterface::{ChannelKeys, InMemoryChannelKeys};
+
+use std::cmp;
+use std::sync::Mutex;
+
+use bitcoin::blockdata::transaction::Transaction;
+use bitcoin::blockdata::script::Script;
+
+use secp256k1;
+use secp256k1::key::SecretKey;
+use secp256k1::{Secp256k1, Signature};
+
+/// Enforces some rules on ChannelKeys calls. 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.
+pub struct EnforcingChannelKeys {
+       pub inner: InMemoryChannelKeys,
+       commitment_number_obscure_and_last: Mutex<(Option<u64>, u64)>,
+}
+
+impl EnforcingChannelKeys {
+       pub fn new(inner: InMemoryChannelKeys) -> Self {
+               Self {
+                       inner,
+                       commitment_number_obscure_and_last: Mutex::new((None, 0)),
+               }
+       }
+}
+impl ChannelKeys for EnforcingChannelKeys {
+       fn funding_key(&self) -> &SecretKey { self.inner.funding_key() }
+       fn revocation_base_key(&self) -> &SecretKey { self.inner.revocation_base_key() }
+       fn payment_base_key(&self) -> &SecretKey { self.inner.payment_base_key() }
+       fn delayed_payment_base_key(&self) -> &SecretKey { self.inner.delayed_payment_base_key() }
+       fn htlc_base_key(&self) -> &SecretKey { self.inner.htlc_base_key() }
+       fn commitment_seed(&self) -> &[u8; 32] { self.inner.commitment_seed() }
+
+       fn sign_remote_commitment<T: secp256k1::Signing>(&self, channel_value_satoshis: u64, channel_funding_script: &Script, feerate_per_kw: u64, commitment_tx: &Transaction, keys: &TxCreationKeys, htlcs: &[&HTLCOutputInCommitment], to_self_delay: u16, secp_ctx: &Secp256k1<T>) -> Result<(Signature, Vec<Signature>), ()> {
+               if commitment_tx.input.len() != 1 { panic!(); }
+               let obscured_commitment_transaction_number = (commitment_tx.lock_time & 0xffffff) as u64 | ((commitment_tx.input[0].sequence as u64 & 0xffffff) << 3*8);
+
+               {
+                       let mut commitment_data = self.commitment_number_obscure_and_last.lock().unwrap();
+                       if commitment_data.0.is_none() {
+                               commitment_data.0 = Some(obscured_commitment_transaction_number ^ commitment_data.1);
+                       }
+                       let commitment_number = obscured_commitment_transaction_number ^ commitment_data.0.unwrap();
+                       assert!(commitment_number == commitment_data.1 || commitment_number == commitment_data.1 + 1);
+                       commitment_data.1 = cmp::max(commitment_number, commitment_data.1)
+               }
+
+               Ok(self.inner.sign_remote_commitment(channel_value_satoshis, channel_funding_script, feerate_per_kw, commitment_tx, keys, htlcs, to_self_delay, secp_ctx).unwrap())
+       }
+}
+
+impl_writeable!(EnforcingChannelKeys, 0, {
+       inner,
+       commitment_number_obscure_and_last
+});