Merge pull request #1208 from TheBlueMatt/2021-12-less-force-close
[rust-lightning] / lightning / src / chain / keysinterface.rs
index c2e78a79394ea84cdbc69e88e269b863a614b948..7be26634916fbaa5268d264528e7099953d6c03d 100644 (file)
@@ -34,7 +34,7 @@ use util::ser::{Writeable, Writer, Readable};
 
 use chain::transaction::OutPoint;
 use ln::chan_utils;
-use ln::chan_utils::{HTLCOutputInCommitment, make_funding_redeemscript, ChannelPublicKeys, HolderCommitmentTransaction, ChannelTransactionParameters, CommitmentTransaction};
+use ln::chan_utils::{HTLCOutputInCommitment, make_funding_redeemscript, ChannelPublicKeys, HolderCommitmentTransaction, ChannelTransactionParameters, CommitmentTransaction, ClosingTransaction};
 use ln::msgs::UnsignedChannelAnnouncement;
 use ln::script::ShutdownScript;
 
@@ -212,6 +212,13 @@ pub trait BaseSign {
        /// Note that the commitment number starts at (1 << 48) - 1 and counts backwards.
        // TODO: return a Result so we can signal a validation error
        fn release_commitment_secret(&self, idx: u64) -> [u8; 32];
+       /// Validate the counterparty's signatures on the holder commitment transaction and HTLCs.
+       ///
+       /// This is required in order for the signer to make sure that releasing a commitment
+       /// secret won't leave us without a broadcastable holder transaction.
+       /// Policy checks should be implemented in this function, including checking the amount
+       /// sent to us and checking the HTLCs.
+       fn validate_holder_commitment(&self, holder_tx: &HolderCommitmentTransaction) -> Result<(), ()>;
        /// Gets the holder's channel public keys and basepoints
        fn pubkeys(&self) -> &ChannelPublicKeys;
        /// Gets an arbitrary identifier describing the set of keys which are provided back to you in
@@ -222,9 +229,17 @@ pub trait BaseSign {
        /// Create a signature for a counterparty's commitment transaction and associated HTLC transactions.
        ///
        /// Note that if signing fails or is rejected, the channel will be force-closed.
+       ///
+       /// Policy checks should be implemented in this function, including checking the amount
+       /// sent to us and checking the HTLCs.
        //
        // TODO: Document the things someone using this interface should enforce before signing.
        fn sign_counterparty_commitment(&self, commitment_tx: &CommitmentTransaction, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<(Signature, Vec<Signature>), ()>;
+       /// Validate the counterparty's revocation.
+       ///
+       /// This is required in order for the signer to make sure that the state has moved
+       /// forward and it is safe to sign the next counterparty commitment.
+       fn validate_counterparty_revocation(&self, idx: u64, secret: &SecretKey) -> Result<(), ()>;
 
        /// Create a signatures for a holder's commitment transaction and its claiming HTLC transactions.
        /// This will only ever be called with a non-revoked commitment_tx.  This will be called with the
@@ -307,7 +322,7 @@ pub trait BaseSign {
        ///
        /// Note that, due to rounding, there may be one "missing" satoshi, and either party may have
        /// chosen to forgo their output as dust.
-       fn sign_closing_transaction(&self, closing_tx: &Transaction, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()>;
+       fn sign_closing_transaction(&self, closing_tx: &ClosingTransaction, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()>;
 
        /// Signs a channel announcement message with our funding key, proving it comes from one
        /// of the channel participants.
@@ -490,6 +505,12 @@ impl InMemorySigner {
                self.channel_parameters.as_ref().unwrap()
        }
 
+       /// Whether anchors should be used.
+       /// Will panic if ready_channel wasn't called.
+       pub fn opt_anchors(&self) -> bool {
+               self.get_channel_parameters().opt_anchors.is_some()
+       }
+
        /// Sign the single input of spend_tx at index `input_idx` which spends the output
        /// described by descriptor, returning the witness stack for the input.
        ///
@@ -558,6 +579,10 @@ impl BaseSign for InMemorySigner {
                chan_utils::build_commitment_secret(&self.commitment_seed, idx)
        }
 
+       fn validate_holder_commitment(&self, _holder_tx: &HolderCommitmentTransaction) -> Result<(), ()> {
+               Ok(())
+       }
+
        fn pubkeys(&self) -> &ChannelPublicKeys { &self.holder_channel_pubkeys }
        fn channel_keys_id(&self) -> [u8; 32] { self.channel_keys_id }
 
@@ -574,8 +599,8 @@ impl BaseSign for InMemorySigner {
 
                let mut htlc_sigs = Vec::with_capacity(commitment_tx.htlcs().len());
                for htlc in commitment_tx.htlcs() {
-                       let htlc_tx = chan_utils::build_htlc_transaction(&commitment_txid, commitment_tx.feerate_per_kw(), self.holder_selected_contest_delay(), htlc, &keys.broadcaster_delayed_payment_key, &keys.revocation_key);
-                       let htlc_redeemscript = chan_utils::get_htlc_redeemscript(&htlc, &keys);
+                       let htlc_tx = chan_utils::build_htlc_transaction(&commitment_txid, commitment_tx.feerate_per_kw(), self.holder_selected_contest_delay(), htlc, self.opt_anchors(), &keys.broadcaster_delayed_payment_key, &keys.revocation_key);
+                       let htlc_redeemscript = chan_utils::get_htlc_redeemscript(&htlc, self.opt_anchors(), &keys);
                        let htlc_sighash = hash_to_message!(&bip143::SigHashCache::new(&htlc_tx).signature_hash(0, &htlc_redeemscript, htlc.amount_msat / 1000, SigHashType::All)[..]);
                        let holder_htlc_key = chan_utils::derive_private_key(&secp_ctx, &keys.per_commitment_point, &self.htlc_base_key).map_err(|_| ())?;
                        htlc_sigs.push(secp_ctx.sign(&htlc_sighash, &holder_htlc_key));
@@ -584,6 +609,10 @@ impl BaseSign for InMemorySigner {
                Ok((commitment_sig, htlc_sigs))
        }
 
+       fn validate_counterparty_revocation(&self, _idx: u64, _secret: &SecretKey) -> Result<(), ()> {
+               Ok(())
+       }
+
        fn sign_holder_commitment_and_htlcs(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<(Signature, Vec<Signature>), ()> {
                let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key);
                let funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &self.counterparty_pubkeys().funding_pubkey);
@@ -625,7 +654,7 @@ impl BaseSign for InMemorySigner {
                let witness_script = {
                        let counterparty_htlcpubkey = chan_utils::derive_public_key(&secp_ctx, &per_commitment_point, &self.counterparty_pubkeys().htlc_basepoint).map_err(|_| ())?;
                        let holder_htlcpubkey = chan_utils::derive_public_key(&secp_ctx, &per_commitment_point, &self.pubkeys().htlc_basepoint).map_err(|_| ())?;
-                       chan_utils::get_htlc_redeemscript_with_explicit_keys(&htlc, &counterparty_htlcpubkey, &holder_htlcpubkey, &revocation_pubkey)
+                       chan_utils::get_htlc_redeemscript_with_explicit_keys(&htlc, self.opt_anchors(), &counterparty_htlcpubkey, &holder_htlcpubkey, &revocation_pubkey)
                };
                let mut sighash_parts = bip143::SigHashCache::new(justice_tx);
                let sighash = hash_to_message!(&sighash_parts.signature_hash(input, &witness_script, amount, SigHashType::All)[..]);
@@ -637,7 +666,7 @@ impl BaseSign for InMemorySigner {
                        let witness_script = if let Ok(revocation_pubkey) = chan_utils::derive_public_revocation_key(&secp_ctx, &per_commitment_point, &self.pubkeys().revocation_basepoint) {
                                if let Ok(counterparty_htlcpubkey) = chan_utils::derive_public_key(&secp_ctx, &per_commitment_point, &self.counterparty_pubkeys().htlc_basepoint) {
                                        if let Ok(htlcpubkey) = chan_utils::derive_public_key(&secp_ctx, &per_commitment_point, &self.pubkeys().htlc_basepoint) {
-                                               chan_utils::get_htlc_redeemscript_with_explicit_keys(&htlc, &counterparty_htlcpubkey, &htlcpubkey, &revocation_pubkey)
+                                               chan_utils::get_htlc_redeemscript_with_explicit_keys(&htlc, self.opt_anchors(), &counterparty_htlcpubkey, &htlcpubkey, &revocation_pubkey)
                                        } else { return Err(()) }
                                } else { return Err(()) }
                        } else { return Err(()) };
@@ -648,17 +677,10 @@ impl BaseSign for InMemorySigner {
                Err(())
        }
 
-       fn sign_closing_transaction(&self, closing_tx: &Transaction, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
-               if closing_tx.input.len() != 1 { return Err(()); }
-               if closing_tx.input[0].witness.len() != 0 { return Err(()); }
-               if closing_tx.output.len() > 2 { return Err(()); }
-
+       fn sign_closing_transaction(&self, closing_tx: &ClosingTransaction, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
                let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key);
                let channel_funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &self.counterparty_pubkeys().funding_pubkey);
-
-               let sighash = hash_to_message!(&bip143::SigHashCache::new(closing_tx)
-                       .signature_hash(0, &channel_funding_redeemscript, self.channel_value_satoshis, SigHashType::All)[..]);
-               Ok(secp_ctx.sign(&sighash, &self.funding_key))
+               Ok(closing_tx.trust().sign(&self.funding_key, &channel_funding_redeemscript, self.channel_value_satoshis, secp_ctx))
        }
 
        fn sign_channel_announcement(&self, msg: &UnsignedChannelAnnouncement, secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()> {
@@ -944,7 +966,8 @@ impl KeysManager {
                        input,
                        output: outputs,
                };
-               transaction_utils::maybe_add_change_output(&mut spend_tx, input_value, witness_weight, feerate_sat_per_1000_weight, change_destination_script)?;
+               let expected_max_weight =
+                       transaction_utils::maybe_add_change_output(&mut spend_tx, input_value, witness_weight, feerate_sat_per_1000_weight, change_destination_script)?;
 
                let mut keys_cache: Option<(InMemorySigner, [u8; 32])> = None;
                let mut input_idx = 0;
@@ -998,6 +1021,12 @@ impl KeysManager {
                        }
                        input_idx += 1;
                }
+
+               debug_assert!(expected_max_weight >= spend_tx.get_weight());
+               // Note that witnesses with a signature vary somewhat in size, so allow
+               // `expected_max_weight` to overshoot by up to 3 bytes per input.
+               debug_assert!(expected_max_weight <= spend_tx.get_weight() + descriptors.len() * 3);
+
                Ok(spend_tx)
        }
 }