In a previous version of the 0-conf code we did not correctly
handle 0-conf channels getting the funding transaction reorg'd out
(and the real SCID possibly changing on us).
This supports routing outbound over 0-conf channels by utilizing
the outbound SCID alias that we assign to all channels to refer to
the selected channel when routing.
If our peer sets a minimum depth of 0, and we're set to trusting
ourselves to not double-spend our own funding transactions, send a
funding_locked message immediately after funding signed.
Note that some special care has to be taken around the
`channel_state` values - `ChannelFunded` no longer implies the
funding transaction is confirmed on-chain. Thus, for example, the
should-we-re-broadcast logic has to now accept `channel_state`
values greater than `ChannelFunded` as indicating we may still need
to re-broadcast our funding tranasction, unless `minimum_depth` is
greater than 0.
Further note that this starts writing `Channel` objects with a
`MIN_SERIALIZATION_VERSION` of 2. Thus, LDK versions prior to
0.0.99 (July 2021) will now refuse to read serialized
Channels/ChannelManagers.
In the next few commits we add support for 0conf channels, allowing
us to have an active channel with HTLC and other updates flying
prior to having an SCID available. This would break several
assumptions made in `ChannelManager`, which we address here by
looking at SCID aliases in addition to SCIDs.
While the HTLC-claim process happens across all MPP parts under one
lock, this doesn't imply that they are claimed fully atomically on
disk. Ultimately, an application can crash after persisting one
`ChannelMonitorUpdate` out of multiple monitor updates needed for
the full claim.
Previously, this would leave us in a very bad state - because of
the all-channels-available check in `claim_funds` we'd refuse to
claim the payment again on restart (even though the
`PaymentReceived` event will be passed to the user again), and we'd
end up having partially claimed the payment!
The fix for the consistency part of this issue is pretty
straightforward - just check for this condition on startup and
complete the claim across all channels/`ChannelMonitor`s if we
detect it.
This still leaves us in a confused state from the perspective of
the user, however - we've actually claimed a payment but when they
call `claim_funds` we return `false` indicating it could not be
claimed.
The `ChannelMonitor` had a field for the counterparty's
`cur_revocation_points`. Somewhat confusingly, this actually stored
the counterparty's *per-commitment* points, not the (derived)
revocation points.
Here we correct this by simply renaming the references as
appropriate. Note the update in `channel.rs` makes the variable
names align correctly.
In `HTLCUpdate` and `OnchainEvent` tracking, we store the HTLC
value (rounded down to whole satoshis). This is somewhat
confusingly referred to as the `onchain_value_satoshis` even though
it refers to the commitment transaction output value, not the value
available on chain (which may have been reduced by an
HTLC-Timeout/HTLC-Success transaction).
In fc77c57c3c we stopped using the
`FInalOnionHopData` in `OnionPayload::Invoice` directly and intend
to remove it eventually. However, in the next few commits we need
access to the payment secret when claimaing a payment, as we create
a new `PaymentPurpose` during the claim process for a new event.
In order to get access to a `PaymentPurpose` without having access
to the `FinalOnionHopData` we here change the storage of
`claimable_htlcs` to store a single `PaymentPurpose` explicitly
with each set of claimable HTLCs.
In fc77c57c3c we stopped using the
`FinalOnionHopData` in `OnionPayload::Invoice` directly and renamed
it `_legacy_hop_data` with the intent of removing it in a few
versions. However, we continue to check that it was included in the
serialized data, meaning we would not be able to remove it without
breaking ability to serialize full `ChannelManager`s.
This fixes that by making the `_legacy_hop_data` an `Option` which
we will happily handle just fine if its `None`.
We have a bunch of fancy infrastructure to ensure we can connect
blocks using all our different connection interfaces, but we only
bother to use it in a few select tests.
This expands our use of `ConnectStyle` to most of our tests by
simply randomizing the style in each test. This makes our tests
non-deterministic, but we print the connection style at start so
that it's easy to reproduce a failure deterministically.
In the next commit we'll randomize the `ConnectStyle` used in each
test. However, some tests are slightly too prescriptive, which we
address here in a few places.
This update also includes a minor refactor. The return type of
`pending_monitor_events` has been changed to a `Vec` tuple with the
`OutPoint` type. This associates a `Vec` of `MonitorEvent`s with a
funding outpoint.
We've also renamed `source/sink_channel_id` to `prev/next_channel_id` in
the favour of clarity.
Instead of including a `Secp256k1` context per
`PeerChannelEncryptor`, which is relatively expensive memory-wise
and nontrivial CPU-wise to construct, we should keep one for all
peers and simply reuse it.
This is relatively trivial so we do so in this commit.
Since its trivial to do so, we also take this opportunity to
randomize the new PeerManager context.
Because we handle messages (which can take some time, persisting
things to disk or validating cryptographic signatures) with the
top-level read lock, but require the top-level write lock to
connect new peers or handle disconnection, we are particularly
sensitive to writer starvation issues.
Rust's libstd RwLock does not provide any fairness guarantees,
using whatever the OS provides as-is. On Linux, pthreads defaults
to starving writers, which Rust's RwLock exposes to us (without
any configurability).
Here we work around that issue by blocking readers if there are
pending writers, optimizing for readable code over
perfectly-optimized blocking.
Only one instance of PeerManager::process_events can run at a time,
and each run always finishes all available work before returning.
Thus, having several threads blocked on the process_events lock
doesn't accomplish anything but blocking more threads.
Here we limit the number of blocked calls on process_events to two
- one processing events and one blocked at the top which will
process all available events after the first completes.
Because the peers write lock "blocks the world", and happens after
each read event, always taking the write lock has pretty severe
impacts on parallelism. Instead, here, we only take the global
write lock if we have to disconnect a peer.
Users are required to only ever call `read_event` serially
per-peer, thus we actually don't need any locks while we're
processing messages - we can only be processing messages in one
thread per-peer.
That said, we do need to ensure that another thread doesn't
disconnect the peer we're processing messages for, as that could
result in a peer_disconencted call while we're processing a
message for the same peer - somewhat nonsensical.
This significantly improves parallelism especially during gossip
processing as it avoids waiting on the entire set of individual
peer locks to forward a gossip message while several other threads
are validating gossip messages with their individual peer locks
held.
This adds the required locking to process messages from different
peers simultaneously in `PeerManager`. Note that channel messages
are still processed under a global lock in `ChannelManager`, and
most work is still processed under a global lock in gossip message
handling, but parallelizing message deserialization and message
decryption is somewhat helpful.
Add test that ensures that channels are closed with
`ClosureReason::DisconnectedPeer` if the peer disconnects before the
funding transaction has been broadcasted.
