Handle retrying sign_counterparty_commitment inb funding failures
authorMatt Corallo <git@bluematt.me>
Tue, 5 Sep 2023 22:21:04 +0000 (22:21 +0000)
committerChris Waterson <waterson@gmail.com>
Wed, 1 Nov 2023 22:24:20 +0000 (15:24 -0700)
If sign_counterparty_commitment fails (i.e. because the signer is
temporarily disconnected), this really indicates that we should
retry the message sending which required the signature later,
rather than force-closing the channel (which probably won't even
work if the signer is missing).

This commit adds retrying of inbound funding_created signing
failures, regenerating the `FundingSigned` message, attempting to
re-sign, and sending it to our peers if we succeed.

lightning/src/ln/channel.rs

index 134be90ea1986fec44c291d1523caeb39894f652..0ca39c95543a96a91e1784576b8d3dee80f29dd3 100644 (file)
@@ -2129,6 +2129,43 @@ impl<SP: Deref> ChannelContext<SP> where SP::Target: SignerProvider  {
                        next_local_nonce: None,
                })
        }
+
+       /// Only allowed after [`Self::channel_transaction_parameters`] is set.
+       fn get_funding_signed_msg<L: Deref>(&mut self, logger: &L) -> (CommitmentTransaction, Option<msgs::FundingSigned>) where L::Target: Logger {
+               let counterparty_keys = self.build_remote_transaction_keys();
+               let counterparty_initial_commitment_tx = self.build_commitment_transaction(self.cur_counterparty_commitment_transaction_number + 1, &counterparty_keys, false, false, logger).tx;
+
+               let counterparty_trusted_tx = counterparty_initial_commitment_tx.trust();
+               let counterparty_initial_bitcoin_tx = counterparty_trusted_tx.built_transaction();
+               log_trace!(logger, "Initial counterparty tx for channel {} is: txid {} tx {}",
+                       &self.channel_id(), counterparty_initial_bitcoin_tx.txid, encode::serialize_hex(&counterparty_initial_bitcoin_tx.transaction));
+
+               match &self.holder_signer {
+                       // TODO (arik): move match into calling method for Taproot
+                       ChannelSignerType::Ecdsa(ecdsa) => {
+                               let funding_signed = ecdsa.sign_counterparty_commitment(&counterparty_initial_commitment_tx, Vec::new(), &self.secp_ctx)
+                                       .map(|(signature, _)| msgs::FundingSigned {
+                                               channel_id: self.channel_id(),
+                                               signature,
+                                               #[cfg(taproot)]
+                                               partial_signature_with_nonce: None,
+                                       })
+                                       .ok();
+
+                               if funding_signed.is_none() {
+                                       log_trace!(logger, "Counterparty commitment signature not available for funding_signed message; setting signer_pending_funding");
+                                       self.signer_pending_funding = true;
+                               } else if self.signer_pending_funding {
+                                       log_trace!(logger, "Counterparty commitment signature available for funding_signed message; clearing signer_pending_funding");
+                                       self.signer_pending_funding = false;
+                               }
+
+                               // We sign "counterparty" commitment transaction, allowing them to broadcast the tx if they wish.
+                               (counterparty_initial_commitment_tx, funding_signed)
+                       }
+               }
+       }
+
 }
 
 // Internal utility functions for channels
@@ -3957,8 +3994,12 @@ impl<SP: Deref> Channel<SP> where
                let commitment_update = if self.context.signer_pending_commitment_update {
                        self.get_last_commitment_update_for_send(logger).ok()
                } else { None };
-               let funding_signed = None;
-               let channel_ready = None;
+               let funding_signed = if self.context.signer_pending_funding && !self.context.is_outbound() {
+                       self.context.get_funding_signed_msg(logger).1
+               } else { None };
+               let channel_ready = if funding_signed.is_some() {
+                       self.check_get_channel_ready(0)
+               } else { None };
                let funding_created = if self.context.signer_pending_funding && self.context.is_outbound() {
                        self.context.get_funding_created_msg(logger)
                } else { None };
@@ -6730,41 +6771,22 @@ impl<SP: Deref> InboundV1Channel<SP> where SP::Target: SignerProvider {
                self.generate_accept_channel_message()
        }
 
-       fn funding_created_signature<L: Deref>(&mut self, sig: &Signature, logger: &L) -> Result<(CommitmentTransaction, CommitmentTransaction, Option<Signature>), ChannelError> where L::Target: Logger {
+       fn check_funding_created_signature<L: Deref>(&mut self, sig: &Signature, logger: &L) -> Result<CommitmentTransaction, ChannelError> where L::Target: Logger {
                let funding_script = self.context.get_funding_redeemscript();
 
                let keys = self.context.build_holder_transaction_keys(self.context.cur_holder_commitment_transaction_number);
                let initial_commitment_tx = self.context.build_commitment_transaction(self.context.cur_holder_commitment_transaction_number, &keys, true, false, logger).tx;
-               {
-                       let trusted_tx = initial_commitment_tx.trust();
-                       let initial_commitment_bitcoin_tx = trusted_tx.built_transaction();
-                       let sighash = initial_commitment_bitcoin_tx.get_sighash_all(&funding_script, self.context.channel_value_satoshis);
-                       // They sign the holder commitment transaction...
-                       log_trace!(logger, "Checking funding_created tx signature {} by key {} against tx {} (sighash {}) with redeemscript {} for channel {}.",
-                               log_bytes!(sig.serialize_compact()[..]), log_bytes!(self.context.counterparty_funding_pubkey().serialize()),
-                               encode::serialize_hex(&initial_commitment_bitcoin_tx.transaction), log_bytes!(sighash[..]),
-                               encode::serialize_hex(&funding_script), &self.context.channel_id());
-                       secp_check!(self.context.secp_ctx.verify_ecdsa(&sighash, &sig, self.context.counterparty_funding_pubkey()), "Invalid funding_created signature from peer".to_owned());
-               }
-
-               let counterparty_keys = self.context.build_remote_transaction_keys();
-               let counterparty_initial_commitment_tx = self.context.build_commitment_transaction(self.context.cur_counterparty_commitment_transaction_number, &counterparty_keys, false, false, logger).tx;
-
-               let counterparty_trusted_tx = counterparty_initial_commitment_tx.trust();
-               let counterparty_initial_bitcoin_tx = counterparty_trusted_tx.built_transaction();
-               log_trace!(logger, "Initial counterparty tx for channel {} is: txid {} tx {}",
-                       &self.context.channel_id(), counterparty_initial_bitcoin_tx.txid, encode::serialize_hex(&counterparty_initial_bitcoin_tx.transaction));
-
-               match &self.context.holder_signer {
-                       // TODO (arik): move match into calling method for Taproot
-                       ChannelSignerType::Ecdsa(ecdsa) => {
-                               let counterparty_signature = ecdsa.sign_counterparty_commitment(&counterparty_initial_commitment_tx, Vec::new(), &self.context.secp_ctx)
-                                       .map(|(sig, _)| sig).ok();
+               let trusted_tx = initial_commitment_tx.trust();
+               let initial_commitment_bitcoin_tx = trusted_tx.built_transaction();
+               let sighash = initial_commitment_bitcoin_tx.get_sighash_all(&funding_script, self.context.channel_value_satoshis);
+               // They sign the holder commitment transaction...
+               log_trace!(logger, "Checking funding_created tx signature {} by key {} against tx {} (sighash {}) with redeemscript {} for channel {}.",
+                       log_bytes!(sig.serialize_compact()[..]), log_bytes!(self.context.counterparty_funding_pubkey().serialize()),
+                       encode::serialize_hex(&initial_commitment_bitcoin_tx.transaction), log_bytes!(sighash[..]),
+                       encode::serialize_hex(&funding_script), &self.context.channel_id());
+               secp_check!(self.context.secp_ctx.verify_ecdsa(&sighash, &sig, self.context.counterparty_funding_pubkey()), "Invalid funding_created signature from peer".to_owned());
 
-                               // We sign "counterparty" commitment transaction, allowing them to broadcast the tx if they wish.
-                               Ok((counterparty_initial_commitment_tx, initial_commitment_tx, counterparty_signature))
-                       }
-               }
+               Ok(initial_commitment_tx)
        }
 
        pub fn funding_created<L: Deref>(
@@ -6791,10 +6813,10 @@ impl<SP: Deref> InboundV1Channel<SP> where SP::Target: SignerProvider {
                let funding_txo = OutPoint { txid: msg.funding_txid, index: msg.funding_output_index };
                self.context.channel_transaction_parameters.funding_outpoint = Some(funding_txo);
                // This is an externally observable change before we finish all our checks.  In particular
-               // funding_created_signature may fail.
+               // check_funding_created_signature may fail.
                self.context.holder_signer.as_mut().provide_channel_parameters(&self.context.channel_transaction_parameters);
 
-               let (counterparty_initial_commitment_tx, initial_commitment_tx, sig_opt) = match self.funding_created_signature(&msg.signature, logger) {
+               let initial_commitment_tx = match self.check_funding_created_signature(&msg.signature, logger) {
                        Ok(res) => res,
                        Err(ChannelError::Close(e)) => {
                                self.context.channel_transaction_parameters.funding_outpoint = None;
@@ -6803,7 +6825,7 @@ impl<SP: Deref> InboundV1Channel<SP> where SP::Target: SignerProvider {
                        Err(e) => {
                                // The only error we know how to handle is ChannelError::Close, so we fall over here
                                // to make sure we don't continue with an inconsistent state.
-                               panic!("unexpected error type from funding_created_signature {:?}", e);
+                               panic!("unexpected error type from check_funding_created_signature {:?}", e);
                        }
                };
 
@@ -6821,6 +6843,13 @@ impl<SP: Deref> InboundV1Channel<SP> where SP::Target: SignerProvider {
 
                // Now that we're past error-generating stuff, update our local state:
 
+               self.context.channel_state = ChannelState::FundingSent as u32;
+               self.context.channel_id = funding_txo.to_channel_id();
+               self.context.cur_counterparty_commitment_transaction_number -= 1;
+               self.context.cur_holder_commitment_transaction_number -= 1;
+
+               let (counterparty_initial_commitment_tx, funding_signed) = self.context.get_funding_signed_msg(logger);
+
                let funding_redeemscript = self.context.get_funding_redeemscript();
                let funding_txo_script = funding_redeemscript.to_v0_p2wsh();
                let obscure_factor = get_commitment_transaction_number_obscure_factor(&self.context.get_holder_pubkeys().payment_point, &self.context.get_counterparty_pubkeys().payment_point, self.context.is_outbound());
@@ -6837,39 +6866,22 @@ impl<SP: Deref> InboundV1Channel<SP> where SP::Target: SignerProvider {
 
                channel_monitor.provide_initial_counterparty_commitment_tx(
                        counterparty_initial_commitment_tx.trust().txid(), Vec::new(),
-                       self.context.cur_counterparty_commitment_transaction_number,
+                       self.context.cur_counterparty_commitment_transaction_number + 1,
                        self.context.counterparty_cur_commitment_point.unwrap(), self.context.feerate_per_kw,
                        counterparty_initial_commitment_tx.to_broadcaster_value_sat(),
                        counterparty_initial_commitment_tx.to_countersignatory_value_sat(), logger);
 
-               self.context.channel_state = ChannelState::FundingSent as u32;
-               self.context.channel_id = funding_txo.to_channel_id();
-               self.context.cur_counterparty_commitment_transaction_number -= 1;
-               self.context.cur_holder_commitment_transaction_number -= 1;
-
-               log_info!(logger, "Generated funding_signed for peer for channel {}", &self.context.channel_id());
+               log_info!(logger, "{} funding_signed for peer for channel {}",
+                       if funding_signed.is_some() { "Generated" } else { "Waiting for signature on" }, &self.context.channel_id());
 
                // Promote the channel to a full-fledged one now that we have updated the state and have a
                // `ChannelMonitor`.
                let mut channel = Channel {
                        context: self.context,
                };
-               let channel_id = channel.context.channel_id.clone();
                let need_channel_ready = channel.check_get_channel_ready(0).is_some();
                channel.monitor_updating_paused(false, false, need_channel_ready, Vec::new(), Vec::new(), Vec::new());
 
-               let funding_signed = if let Some(signature) = sig_opt {
-                       Some(msgs::FundingSigned {
-                               channel_id,
-                               signature,
-                               #[cfg(taproot)]
-                               partial_signature_with_nonce: None,
-                       })
-               } else {
-                       channel.context.signer_pending_funding = true;
-                       None
-               };
-
                Ok((channel, funding_signed, channel_monitor))
        }
 }