Caching of input material for HTLC transaction was introducted
prevently but since then API (InputMaterial) has changed
between ChannelMonitor and OnchainTxHandler
Implementing dynamic fee bumping implied to cache transaction material
including its witness, to generate a bumped version if needed.
ChannelMonitor is slowly rescoped to its parsing function with ongoing
patchset and data duplicata are removed. If signed local commitment tx
access is needed, it's done through OnchainTxHandler extended API
For test framework purpose, we use the test-only method
ChannelMonitor::unsafe_get_latest_local_commitment_txn to intentionally
generate unsafe local commitment to exerce revocation logic.
By caching current local commitment number instead of deciphering
it from local commitment tx, we may remove local commitment tx
from ChannelMonitor in next commit.
Local Commitment Transaction can't be bumped without anchor outputs
so their generation is one-time for now. We move them in
OnchainTxHandler for simplifying ChannelMonitor and to prepare
storage of keys material behind one external signer interface.
Some tests break due to change in transaction broadcast order but
number of transactions broadcast should stay the same.
To prevent any unsafe state discrepancy between offchain and onchain,
once local commitment transaction has been signed due to an event
(either block height for HTLC-timeout or channel force-closure), don't
allow any further update of local commitment transaction view
to avoid delivery of revocation secret to counterparty for the
aformentionned signed transaction.
As transaction generation and signature is headed to be moved
inside OnchainTxHandler, cache local_commitment_tx signed by remote.
If access to local commitment transaction is needed, we extend Onchain
TxHandler API to do so.
Previously, we would regenerate this class of txn twice due to
block-rescan triggered by new watching outputs registered.
This commmit doesn't change behavior, it only tweaks TestBroadcaster
to ensure we modify cleanly tests anticipating next commit
refactor.
Extend external signer interface to sign local commitment transactions
on its behalf without seckey passing. This move will allow us to remove
key access from ChannelMonitor hot memory in further work.
Local commitment transaction should stay half-signed by remote until
we need to broadcast for a channel force-close or a HTLC to timeout onchain.
Add an unsafe test-only version of sign_local_commitment to fulfill our
test_framework needs.
ChannelManager::send_payment stopped utilizing its ownership of the
Route with MPP (which, for readability, now clone()s the individual
paths when creating HTLCSource::OutboundRoute objects). While this
isn't ideal, it likely also makes sense to ensure that the user has
access to the Route after sending to correlate individual path
failures with the paths in the route or, in the future, retry
individual paths.
Thus, the easiest solution is to just take the Route by reference,
allowing the user to retain ownership.
This rather dramatically changes the return type of send_payment
making it much clearer when resending is safe and allowing us to
return a list of Results since different paths may have different
return values.
Previously if we claimed an MPP where a previous-hop channel was
closed while we were waitng for the user to provide us the preimage
we'd simply skip claiming that HTLC without letting the user know.
This refactors the claim logic to first check that all the channels
are still available (which is actually all we need - we really
mostly care about updating the channel monitors, not the channels
themselves) and then claim the HTLCs in the same lock, ensuring
atomicity.
Base AMP is centered around the concept of a 'payment_secret` - an
opaque 32-byte random string which is used to authenticate the
sender to the recipient as well as tie the various HTLCs which
make up one payment together. This new field gets exposed in a
number of places, though sadly only as an Option for backwards
compatibility when sending to a receiver/receiving from a sender
which does not support Base AMP.
Sadly a huge diff here, but almost all of it is changing the method
signatures for sending/receiving/failing HTLCs and the
PaymentReceived event, which all now need to expose an
Option<[u8; 32]> for the payment_secret.
It doesn't yet properly fail back pending HTLCs when the full AMP
payment is never received (which should result in accidental
channel force-closures). Further, as sending AMP payments is not
yet supported, the only test here is a simple single-path payment
with a payment_secret in it.
Upon channel failure, any pending HTLCs in a channel's holding cell must
be failed backward. The added test exercises this behavior and
demonstrates a deadlock triggered within the handle_error!() macro. The
deadlock occurs when the channel_state lock is already held and then
reacquired when finish_force_close_channel() is called.
This partially reverts 933ae34703,
though note that 933ae34703 fixed a
similar deadlock while introducing this one.
If we have HTLCs to fail backwards, handle_error!() will call
finish_force_close_channel() which will attempt to lock channel_state
while it is locked at the original caller. Instead, hold the lock for
shorter scopes such that it is not held upon entering handle_error!().
Co-authored-by: Matt Corallo <git@bluematt.me>
Co-authored-by: Jeffrey Czyz <jkczyz@gmail.com>
check_spend_local_transaction is tasked with detection of
onchain local commitment transaction and generate HTLC transaction.
Signing an already onchain tx isn't necessary.
Rename ChannelMonitor::Storage to OnchainDetection,
holder of channel state (base_key+per_commitment_point)
to detect onchain transactions accordingly.
Going further between splitting detection and transaction
generation, we endow OnchainTxHandler with keys access.
That way, in latter commits, we may remove secret keys entirely
from ChannelMonitor.
Watchtower will be supported through external signer interface
where a watchtower implementation may differ from a local one
by the scope of key access and pre-signed datas.
If any monitors are out of sync with the Channel, we previously
closed the channel, but we should really only do that if the
monitor is ahead of the channel, opting to call the whole thing
invalid if the channel is ahead of the monitor.
We delay SpendableOutputDescriptor until reaching ANTI_REORG_DELAY
to avoid misleading user wallet in case of reorg and alternative
settlement on a channel output.
Fix tests in consequence.
is_paying_spendable_output
Add ChannelMonitor::broadcasted_local_revokable_script to detect
onchain local txn paying back to us.
Fix tests in consequence
