1107ab06c3 introduced an API to have a
ChannelKeys implementer sign HTLC transactions by calling into the
LocalCommitmentTransaction object, which would then store the tx.
This API was incredibly awkward, both because it required an
external signer trust our own internal interfaces, but also because
it didn't allow for any inspection of what was about to be signed.
Further, it signed the HTLC transactions one-by-one in a somewhat
inefficient way, and there isn't a clear way to resolve this (as
the which-HTLC parameter has to refer to something in between the
HTLC's arbitrary index, and its index in the commitment tx, which
has "holes" for the non-HTLC outputs and skips some HTLCs).
We replace it with a new function in ChannelKeys which allows us
to sign all HTLCs in a given commitment transaction (which allows
for a bit more effeciency on the signers' part, as well as
sidesteps the which-HTLC issue). This may also simplify the signer
implementation as we will always want to sign all HTLCs spending a
given commitment transaction at once anyway.
We also de-mut the LocalCommitmentTransaction passed to the
ChanKeys, instead opting to make LocalCommitmentTransaction const
and avoid storing any new HTLC-related data in it.
This cleans up sign_local_commitment somewhat by returning a
Result<Signaure, ()> over the local commitment transaction instead
of modifying the struct which was passed in.
This is the first step in making LocalCommitmentTransaction a
completely pub struct, using it just to communicate enough
information to the user to allow them to construct a signaure
instead of having it contain a bunch of logic.
This should make it much easier to implement a custom ChannelKeys
by disconnecting the local commitment transaction signing from our
own datastructures.
We want to avoid a third-party channel closure, where a random node
by sending us a payment expiring at current height, would trigger our
onchain logic to close the channel due to a near-expiration.
Relatively simple test that, after a monitor update fails, we get
the right return value and continue with the bits of the MPP that
did not send after the monitor updating is restored.
We only do this for incoming HTLCs directly as we rely on channel
closure and HTLC-Timeout broadcast to fail any HTLCs which we
relayed onwards where our next-hop doesn't update_fail in time.
The ChanKeys is created with knowledge of the Channel's value and
funding redeemscript up-front, so we should not be providing it
when making signing requests.
Not only was watchtower mode never implemented, but the bits that
we had were removed some time ago. It doesn't seem likely we'll
move forward with a "watchtower-mode" ChannelMonitor, instead
we'll likely have some other, separate struct for this.
After we moved the ChannelMonitor creation later during Channel
init, we never went back and cleaned up ChannelMonitor to remove
a number of now-useless Option<>s, so we do that now.
HTLC Transaction can't be bumped without sighash changes
so their gneeration is one-time for nwo. 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 broadcaster order.
Number of transactions may vary because of temporary anti-duplicata
tweak can't dissociate between 2- broadcast from different
origins (ChannelMonitor, ChannelManager) and 2-broadcast from same
component.
Extend external signer interface to sign HTLC transactions on its
behalf without seckey passing. This move will allow us to remove
key access access from ChannelMonitor hot memory in further work.
HTLC transactions should stay half-signed by remote until
we need to broadcast them for timing-out/claiming HTLCs onchain.
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.
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.
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.
Enforce a minimum htlc_minimum_msat of 1.
Instead of computing dynamically htlc_minimum_msat based on feerate,
relies on user-provided configuration value. This let user compute
an economical-driven channel parameter according to network dynamics.
This is a somewhat-obvious oversight in the capabilities of
rust-lightning, though not a particularly interesting one until we
start relying on node_features (eg for variable-length-onions and
Base AMP).
Sadly its not fully automated as we don't really want to store the
list of available addresses from the user. However, with a simple
call to ChannelManager::broadcast_node_announcement and a sensible
peer_handler, the announcement is made.
This is a cheap way to fix an error in Router serialization
roundtrip due to us calling read_to_end during the read of
channel/node announcement/updates. During normal message reading,
we only have limited bytes to read (specifically the message buffer)
so this is fine, however when we read them inside Router, we have
more data from other fields of the Router available as well. Thus,
we end up reading the entire rest of the Router into one message
field, and failing to deserialize.
Because such fields are always stored in Option<>s, we can simply
use a LengthLimitingStream in the Option<> serialization format and
make only the correct number of bytes available.
By using a variable-length integer for the new field, we avoid
wasting space compared to the existing serialization format.
This makes Readable symmetric with Writeable and makes sense -
something which is Readable should be Readable for any stream which
implements std::io::Read, not only for a stream type it decides on.
This solves some lifetime-compatibility issues in trying to read()
from a LengthLimitingReader in arbitrary Readable impls.
As noted in the docs, Events don't round-trip fully, but round-trip
in a way that is useful for ChannelManagers, specifically some events
don't make sense anymore after a restart.
This removes the somewhat-easy-to-misuse Clone from ChannelMonitors,
opening us up to being able to track Events in ChannelMonitors with
less risk of misuse.
Sadly it doesn't remove the Clone requirement for ChannelKeys,
though gets us much closer - we now just need to request a second
copy once when we go to create the ChannelMonitors.
This removes the ability to merge ChannelMonitors in favor of
explicit ChannelMonitorUpdates. It further removes
ChannelManager::test_restore_channel_monitor in favor of the new
ChannelManager::channel_monitor_updated method, which explicitly
confirms a set of updates instead of providing the latest copy of
each ChannelMonitor to the user.
This removes almost all need for Channels to have the latest
channel_monitor, except for broadcasting the latest local state.
This is the first step in migrating ChannelMonitor updating logic
to use incremental Update objects instead of copying the
ChannelMonitors themselves and insert_combine()ing them.
This adds most of the scaffolding and updates relevant comments to
refer to the new architecture, without changing how any actual
updates occur.
This is important for a number of reasons:
* Firstly, I hit this trying to implement rescan in the demo
bitcoinrpc client - if individual ChannelMonitors are out of
sync with each other, we cannot add them all into a
ManyChannelMonitor together and then rescan, but need to rescan
them individually without having to do a bunch of manual work.
Of the three return values in ChannelMonitor::block_connected,
only the HTLCsource stuff that is moved here makes no sense to
be exposed to the user.
* Secondly, the logic currently in ManyChannelMonitor cannot be
reproduced by the user! HTLCSource is deliberately an opaque
type but we use its data to decide which things to keep when
inserting into the HashMap. This would prevent a user from
properly implementing a replacement ManyChannelMonitor, which is
unacceptable.
* Finally, by moving the tracking into ChannelMonitor, we can
serialize them out, which prevents us from forgetting them when
loading from disk, though there are still other races which need
to be handled to make this fully safe (see TODOs in
ChannelManager).
This is safe as no two entries can have the same HTLCSource across
different channels (or, if they did, it would be a rather serious
bug), though note that, IIRC, when this code was added, the
HTLCSource field in the values was not present.
We also take this opportunity to rename the fetch function to match
our other event interfaces, makaing it clear that by calling the
function the set of HTLCUpdates will also be cleared.
Previously, if new ouputs were found to be watched as part
of channel operations, the block was rescan which triggers
again parser and generation of transactions already issued.
This commit first modifies the test framework without
altering further ChannelMonitor.
ChannelMonitor refactoring is introduced in a latter commit.
There's quite a bit of machinery included here, but it neatly
avoids any dynamic allocation during TLV deserialization, and the
calling side looks nice and simple. The macro-generated code is
pretty nice, though has some redundant if statements (I haven't
checked if they get optimized out yet, but I can't imagine they
don't).
This adds a number of new stream adapters to track and/or calculate
the number of bytes read/written to an underlying stream, as well
as wrappers for the two (?!) variable-length integer types that TLV
introduces.
This prepares for variable-length per-hop-data by wrapping the full
hop_data field in a decrypting stream, with a few minor
optimizations and redundant allocations to boot.
PeerManager determines whether the initial_routing_sync feature bit
should be set when sending Init messages to peers. Move this to the
Router as it is better able to determine if a full sync is needed.
* Fixed a number of grammar issues
* Clarified the docs for users who are intimately farmiliar with
arbitrary lines of text copied from the BOLTs
* Added a bit more text so that things are easier to read and less
disjoint.
* Clarified exactly how the witness stack should look since I had
to go dig for it.
Additional changes:
* Update fuzz crate to match ChannelManager's new API
* Update lightning-net-tokio library to match ChannelManager's new ChannelMonitor Deref API
* Update tests to match ChannelManager's new ChannelMonitor Deref API
