If a persister returns a temporary failure, the channel monitor should be able
to be put on ice and then revived later. If a persister returns a permanent
failure, the channel should be force closed.
Intended to be a cross-platform implementation of the
channelmonitor::Persist trait.
This adds a new lightning-persister crate, that uses the
newly exposed lightning crate's test utilities.
Notably, this crate is pretty small right now. However, due to
future plans to add more data persistence (e.g. persisting the
ChannelManager, etc) and a desire to avoid pulling in filesystem
usage into the core lightning package, it is best for it to be
separated out.
Note: Windows necessitates the use of OpenOptions with the `write`
permission enabled to `sync_all` on a newly opened channel's
data file.
- 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.
This test is a mutation to underscore the detetection logic bug
we had before #653. HTLC value routed is above the remaining
balance, thus inverting HTLC and `to_remote` output. HTLC
will come second and it wouldn't be seen by pre-#653 detection
as we were eneumerate()'ing on a watched outputs vector (Vec<TxOut>)
thus implictly relying on outputs order detection for correct
spending children filtering.
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 9e03087d6a we started setting
`opt-level` only on profile.test and not profile.dev. When that
commit was authored I tested only that rustc was being called with
opt-level set in its flags, not that the resulted run ran at the
speed I expected. It seems profile.test isn't applied properly to
dependencies or so, resulting in tests running much slower than
they do at profile.dev.opt-level=1.
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()`.
This also pays a fee on the transactions we generate in response to
SpendableOutputDescriptors in tests.
This fixes the known issues in #630, though we should test for
standardness in other ways as well.
This resolves a number of bugs around how we calculate feerates on
closing transactions:
* We previously calculated the weight wrong both by always
counting two outputs instead of counting the number of outputs
that actually exist in the closing transaction and by not
counting the witness redeemscript.
* We use assertions to check the calculated weight matches what we
actually build (with debug_assertions for variable-length sigs).
* As an additional sanity check, we really should check that the
transaction had at least min-relay-fee when we were the channel
initator.
It was noticed (via clippy) by @casey that we were taking and then
immediately dropping the total_consistency_lock because `let _ =`
doesn't actually bind the response to anything. This appears to be
a consequence of wanting `if let Some(_) =` to not hold a ref to
the contained value at all, but is relatively surprising to me.
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.
Outputs to watch are tracked by ChannelMonitor as of
73dce207dd. Instead of determining new
outputs to watch independently using ChainWatchedUtil, do so by
comparing against outputs already tracked. Thus, ChainWatchedUtil and
WatchEvent are no longer needed.
WatchEventProvider served as a means for replacing ChainWatchInterface.
However, it requires users to explicitly fetch WatchEvents, even if not
interested in them. Replace WatchEventProvider by chain::Filter, which
is an optional member of ChainMonitor. If set, interesting transactions
and output spends are registered such that blocks containing them can be
retrieved from a chain source in an efficient manner.
This is useful when the chain source is not a full node. For Electrum,
it allows for pre-filtered blocks. For BIP157/158, it serves as a means
to match against compact filters.
BlockNotifier was removed in the previous commit, thus ChainListener is
no longer needed. Instead, anything needing chain events should be
notified directly.
BlockNotifier is a convenience for handing blocks to listeners. However,
it requires that each listener conforms to the ChainListener interface.
Additionally, there are only two listeners, ChannelManager and
ChainMonitor, the latter of which may not be used when monitoring
channels remotely. Remove BlockNotifier since it doesn't provide much
value and constrains each listener to a specific interface.
ChainMonitor's template Key parameter was meant to allow supporting
both local monitoring, where Key=OutPoint, and watchtowers, where Key=
(PublicKey, u32). Use OutPoint directly since the watchtower case will
not be supported this way.
