This change modifies six structs that were keeping
track of anchors features with an `opt_anchors` field,
as well as another field keeping track of nonzero-fee-
anchor-support.
Specifically, introduce a new constructor for an anchors-
supporting feature set, as well as methods that will
maintain forwards-compatible deserialization in older
versions.
Downstream crates building fur fuzzing will usually set
`--cfg=fuzzing` as a side-effect of the Rust fuzzing tooling. Thus,
we should ensure we build without failure in such cases.
We do this here by simply relying on the `_test_utils` feature,
rather than conditionally-compiling in modules based on the
`fuzzing` flag.
Make sure the penultimate hop took the amount of fee that they claimed to take.
Without checking this TLV, we're heavily relying on the receiving wallet code
to correctly implement logic to calculate that that the fee is as expected.
Useful for penultimate hops in routes to take an extra fee, if for example they
opened a JIT channel to the payee and want them to help bear the channel open
cost.
We need the channel lock for constructing a pending HTLC's status because we
need to know if the channel accepts underpaying HTLCs in upcoming commits.
Certain users may not care how their UTXOs are selected, or their wallet
may not expose enough controls to fully implement the
`CoinSelectionSource` trait. As an alternative, we introduce another
trait `WalletSource` they could opt to implement instead, which is much
simpler as it just returns the set of confirmed UTXOs that may be used.
This trait implementation is then consumed into a wrapper `Wallet` which
implements the `CoinSelectionSource` trait using a "smallest
above-dust-after-spend first" coin selection algorithm.
This allows users to bump their commitments and HTLC transactions
without having to worry about all the little details to do so. Instead,
we'll just require that they implement the `CoinSelectionSource` trait
over their wallet/UTXO source, granting the event handler permission to
spend confirmed UTXOs for the transactions it'll produce.
While the event handler should in most cases produce valid transactions,
assuming the provided confirmed UTXOs are valid, it may not produce
relayable transactions due to not satisfying certain Replace-By-Fee
(RBF) mempool policy requirements. Some of these require that the
replacement transactions have a higher feerate and absolute fee than the
conflicting transactions it aims to replace. To make sure we adhere to
these requirements, we'd have to persist some state for all transactions
the event handler has produced, greatly increasing its complexity. While
we may consider implementing so in the future, we choose to go with a
simple initial version that relies on the OnchainTxHandler's bumping
frequency. For each new bumping attempt, the OnchainTxHandler proposes a
25% feerate increase to ensure transactions can propagate under
constrained mempool circumstances.
In a future commit, we plan to expand `BumpTransactionEvent` variants to
include the unique identifier assigned to pending output claims by the
`OnchainTxHandler` when a commitment is broadcast/confirmed. This
requires making it public in our API. We also choose to rename it to
`ClaimId` for the benefit of users, as the previous `PackageID` term
could be interpreted to be the ID of a BIP-331 transaction package.
While the previous way of computing the identifier was safe, it wouldn't
have been in certain scenarios if we considered splitting aggregated
packages. While this type of splitting has yet to be implemented, it may
come in the near future. To ensure we're prepared to handle such, we
opt to instead commit to all of the HTLCs to claim in the request.
It's unclear what values 1-hop blinded paths should set their BlindedPayInfos
to, because those values are meant to refer to the fees/cltv delta on the path
*between* the intro node and the destination. We zero out these values in the
new variant's methods so they don't mess with path finding/construction.
This commit also adds two new maps to `PeerState` for keeping track
of `OutboundV1Channel`s and `InboundV1Channel`s so that further
commits are a bit easier to review.
