Add a utility for syncing a set of chain listeners to a common chain
tip. Required to use before creating an SpvClient when the chain
listener used with the client is actually a set of listeners each of
which may have had left off at a different block. This would occur when
the listeners had been persisted individually at different frequencies
(e.g., a ChainMonitor's individual ChannelMonitors).
The `ChannelKeys` object really isn't about keys at all anymore,
its all about signing. At the same time, we rename the type aliases
used in traits from both `ChanKeySigner` and `Keys` to just
`Signer` (or, in contexts where Channel isnt clear, `ChanSigner`).
Sadly, there's just not really a practical way to map a slice of
objects in our current bindings infrastructure - either we take
ownership of the underlying objects and move them into a Vec, or we
need to leave the original objects in place and have a list of
pointers to the Rust objects. Thus, the only practical mapping is
to create a slice of references using the pointers we have.
This adds a utility method, `KeysManager::spend_spendable_outputs`,
which constructs a Transaction from a given set of
`SpendableOutputDescriptor`s, deriving relevant keys as needed.
It also adds methods which can sign individual inputs where
channel-specific key derivation is required to
`InMemoryChannelKeys`, making it easy to sign transaction inputs
when a custom `KeysInterface` is used with `InMemoryChannelKeys`.
KeyManager::new() took a bitcoin::Network parameter which needs to
be passed to the BIP 32 Extended Key constructor, but because we
never write out the BIP 32 serialization, it isn't used. Instead,
we just pass a dummy value into `ExtendedPrivKey`, dropping the
unused argument to KeysManager::new().
Both SpendableOutputDescriptor::DynamicOutputP2WSH and
SpendableOutputDescriptor::StaticOutputCounterpartyPayment are
relevant only in the context of a given channel, making them
candidates for being passed into helper functions in
`InMemoryChannelKeys`. This moves them into their own structs so
that they can later be used standalone.
This adds a channel_value_satoshis field to
SpendableOutputDescriptors as it is required to recreate our
InMemoryChannelKeys. It also slightly expands documentation.
Instead of `key_derivation_params` being a rather strange type, we
call it `channel_keys_id` and give it a generic 32 byte array. This
should be much clearer for users and also more flexible.
The only API change outside of additional derives is to change
the inner field in `DecodeError::Io()` to an `std::io::ErrorKind`
instead of an `std::io::Error`. While `std::io::Error` obviously
makes more sense in context, it doesn't support Clone, and the
inner error largely doesn't have a lot of value on its own.
We want to make sure that we don't sign revoked transactions.
Given that ChannelKeys are not singletons and revocation enforcement is stateful,
we need to store the revocation state in KeysInterface.
Signing the commitment transaction is almost always followed by signing the attached HTLC transactions, so fold the signing operations into a single method.
This drops any direct calls to a generic `ChannelKeys::read()` and
replaces it with the new `KeysInterface::read_chan_signer()`. Still,
under the hood all of our own `KeysInterface::read_chan_signer()`
implementations simply call out to a `Readable::read()` implemention.
This adds a new method to the general cross-channel `KeysInterface`
which requires it to handle the deserialization of per-channel
signer objects. This allows the deserialization of per-channel
signers to have more context available, which, in the case of the
C bindings, includes the actual KeysInterface information itself.
There's no reason to have ChannelMonitor::write_for_disk instead of
just using the Writeable trait anymore. Previously, it was used to
differentiate with `write_for_watchtower`, but support for
watchtower-mode ChannelMonitors was never completed and the partial
bits were removed long ago.
This has the nice benefit of hitting the custom Writeable codepaths
in C bindings instead of trying to hit trait-generics paths.
It doesn't make sense to ever build a lightning node which doesn't
ever write ChannelMonitors to disk, so having a ChannelKeys object
which doesn't implement Writeable is nonsense.
Here we require Writeable for all ChannelKeys objects, simplifying
code generation for C bindings somewhat.
We only actually use two of the fields in ChannelKeys inside a
ChannelMonitor - the holder revocation_basepoint and the
derivation parameters. Both are relatively small, so there isn't
a lot of reason to hold a full copy of the ChannelKeys (with most
of the interaction with it being inside the OnchainTxHandler).
Further, this will avoid calling read on a `ChannelKeys` twice,
which is a somewhat strange API quirk.
CommitmentTransaction maintains the per-commitment transaction fields needed to construct the associated bitcoin transactions (commitment, HTLC). It replaces passing around of Bitcoin transactions. The ChannelKeys API is modified accordingly.
By regenerating the transaction when implementing a validating external signer, this allows a higher level of assurance that all relevant aspects of the transactions were checked for policy violations.
ChannelTransactionParameters replaces passing around of individual per-channel fields that are needed to construct Bitcoin transactions.
Eliminate ChannelStaticData in favor of ChannelTransactionParameters.
Use counterparty txid instead of tx in channelmonitor update.
Like the previous commit for channel-closed monitor updates for
inbound channels during processing of a funding_created message,
this resolves a more general issue for closing outbound channels
which have sent a funding_created but not yet received a
funding_signed.
This issue was also detected by full_stack_target.
To make similar issues easier to detect in testing and fuzzing, an
additional assertion is added to panic on updates to a channel
monitor before registering it.
If we receive a preimage for an outgoing HTLC that solves an output on a
backwards force-closed channel, we need to claim the output on-chain.
Note that this commit also gets rid of the channel monitor redundantly setting
`self.counterparty_payment_script` in `check_spend_counterparty_transaction`.
Co-authored-by: Antoine Riard <ariard@student.42.fr>
Co-authored-by: Valentine Wallace <vwallace@protonmail.com>
Now callers will separately retrieve the claim requests/
holder revokable script and the new watched holder outputs.
This will be used in the next commit for times when we
need to get holder claim requests, but don't have access to
the holder commitment transaction.
Helpful for debugging. I also included the change in the provide_preimage method
signature which will be used in an upcoming commit, because commit-wise it was
easier to combine the changes.
If the channel is hitting the chain right as we receive a preimage,
previous to this commit the relevant ChannelMonitor would never
learn of this preimage.
- The ChainMonitor should:
Whenever a new channel is added or updated, these updates
should be conveyed to the persister and persisted to disk.
Even if the update errors while it's being applied, the
updated monitor still needs to be persisted.
We remove test_no_failure_dust_htlc_local_commitment from our test
framework as this test deliberately throwing junk transaction in
our monitoring parsing code is hitting new assertions.
This test was added in #333, but it sounds as an oversight as the
correctness intention of this test (i.e verifying lack of dust
HTLCs canceling back in case of junk commitment transaction) doesn't
currently break.
Previously, outputs were monitored based on txid and an index yelled
from an enumeration over the returned selected outputs by monitoring
code. This is always have been broken but was only discovered while
introducing anchor outputs as those ones rank always first per BIP69.
We didn't have test cases where a HTLC was bigger than a party balance
on a holder commitment and thus not ranking first.
Next commit introduce test coverage.
In review of the final doc changes in #649, I noticed there
appeared to be redundant monitored-outpoints function in
`ChannelMonitor` - `get_monitored_outpoints()` and
`get_outputs_to_watch()`.
In 6f08779b04,
get_monitored_outpoints() was added, with its behavior largely the
same as today's - only returning the set of remote commitment txn
outputs that we've learned about on-chain. This is clearly not
sufficient, and in 73dce207dd,
`get_outputs_to_watch` was added which was overly cautious to
ensure nothing was missed. Still, the author of 73dce207dd
(me) seemed entirely unaware of the work in 6f08779b04
(also me), despite the function being the literal next function in
the same file. This is presumably because it was assumed that
`get_monitored_outpoints` referred to oupoints for which we should
monitor for spends of (which is true), while `get_outputs_to_watch`
referred to outpouts which we should monitor for the transaction
containing said output (which is not true), or something of that
nature. Specifically, it is the expected behavior that the only
time we care about `Filter::register_tx` is for the funding
transaction (which we aren't aware of the inputs of), but for all
other transactions we register interest on the basis of an outpoint
in the previous transaction (ie via `Filter::register_output`).
Here we drop the broken-on-day-one `get_monitored_outpoints()`
version, but assert in testing that the values which it would return
are all present in `get_outputs_to_watch()`.
Previously, we had a concept of "rescaning" blocks when we detected
a need to monitor for a new set of outputs in future blocks while
connecting a block. In such cases, we'd need to possibly learn about
these new spends later in the *same block*, requiring clients who
filter blocks to get a newly-filtered copy of the same block. While
redoing the chain access API, it became increasingly clear this was
an overly complicated API feature, and it seems likely most clients
will not use it anyway.
Further, any client who *does* filter blocks can simply update their
filtering algorithm to include any descendants of matched
transactions in the filter results, avoiding the need for rescan
support entirely.
Thus, it was decided that we'd move forward without rescan support
in #649, however to avoid significant further changes in the
already-large 649, we decided to fully remove support in a
follow-up.
Here, we remove the API features that existed for rescan and fix
the few tests to not rely on it.
After this commit, we now only ever have one possible version of
block connection transactions, making it possible to be
significantly more confident in our test coverage actually
capturing all realistic scenarios.
Given the chain::Watch interface is defined in terms of ChannelMonitor
and ChannelMonitorUpdateErr, move channelmonitor.rs from the ln module
to the chain module.
Transaction data from a block may be filtered before it is passed to
block_connected functions, which may need the index of each transaction
within the block. Rather than define each function in terms of a slice
of tuples, define a type alias for the slice where it can be documented.
