During event handling, ChannelManager methods may need to be called as
indicated in the Event documentation. Ensure that these calls are
idempotent for the same event rather than panicking. This allows users
to persist events for later handling without needing to worry about
processing the same event twice (e.g., if ChannelManager is not
persisted but the events were, the restarted ChannelManager would return
some of the same events).
For some reason rustc was deciding on a type for the `Option` being
deserialized for us as `_user_payment_id`. This really, really,
absolutely should have been a compile failure - the type (with
methods called on it!) was ambiguous! Instead, rustc seems to have
been defaulting to `Option<()>`, causing us to read zero of the
eight bytes in the `user_payment_id` field, which returns an
`Err(InvalidValue)` error as TLVs must always be read fully.
This should likely be reported to rustc as its definitely a bug,
but I cannot seem to cause the same error on any kinda of
vaguely-minimized version of the same code.
Found by `chanmon_consistency` fuzz target.
A peer providing a channel_reserve_satoshis of 0 (or less than our
dust limit) is insecure, but only for them. Because some LSPs do it
with some level of trust of the clients (for a substantial UX
improvement), we explicitly allow it. Because its unlikely to
happen often in normal testing, we test it explicitly here.
`scoring::Time` exists in part to make testing the passage of time
in `Scorer` practical. To allow no-std users to provide a time
source it was exposed as a trait as well. However, it seems
somewhat unlikely that a no-std user is going to have a use for
providing their own time source (otherwise they wouldn't be a
no-std user), and likely they won't have a graph in memory either.
`scoring::Time` as currently written is also exceptionally hard to
write C bindings for - the C bindings trait mappings relies on the
ability to construct trait implementations at runtime with function
pointers (i.e. `dyn Trait`s). `scoring::Time`, on the other hand,
is a supertrait of `core::ops::Sub` which requires a `sub` method
which takes a type parameter and returns a type parameter. Both of
which aren't practical in bindings, especially given the
`Sub::Output` associated type is not bound by any trait bounds at
all (implying we cannot simply map the `sub` function to return an
opaque trait object).
Thus, for simplicity, we here simply seal `scoring::Time` and make
it effectively-private, ensuring the bindings don't need to bother
with it.
Ultimately we likely need to wrap the locked `Score` in a struct
that exposes writeable somehow, but because all traits have to be
fully concretized for C bindings we'll still need `Writeable` on
all `Score` in order to expose `Writeable` on the locked score.
Otherwise, we'll only have a `LockedScore` with a `Score` visible
that only has the `Score` methods, never the original type.
Previously, `holder_selected_channel_reserve_satoshis` and
`holder_max_htlc_value_in_flight_msat` were constant functions
of the channel value satoshis. However, in the future we may allow
allow users to specify it. In order to do so, we'll need to track
them explicitly, including serializing them as appropriate.
We go ahead and do so here, in part as it will make testing
different counterparty-selected channel reserve values easier.
A single PaymentSent event is generated when a payment is fulfilled.
This is occurs when the preimage is revealed on the first claimed HTLC.
For subsequent HTLCs, the event is not generated.
In order to score channels involved with a successful payments, the
scorer must be notified of each successful path involved in the payment.
Add a PaymentPathSuccessful event for this purpose. Generate it whenever
a part is removed from a pending outbound payment. This avoids duplicate
events when reconnecting to a peer.
This adds a new (non-feature) cfg argument `c_bindings` which will
be set when building C bindings. With this, we can (slightly) tweak
behavior and API based on whether we are being built for Rust or C
users.
Ideally we'd never need this, but as long as we can keep the API
consistent-enough to avoid material code drift, this gives us a
cheap way of doing the "right" thing for both C and Rust when the
two are in tension.
We also move lightning-background-processor to support the same
MSRV as the main lightning crate, instead of only
lightning-net-tokio's MSRV.
Previously, we would reject inbound channels if the funder wasn't
able to meet our channel reserve on their first commitment
transaction only if they also failed to push enough to us for us
to not meet their initial channel reserve as well.
There's not a lot of reason to care about us meeting their reserve,
however - its largely expected that they may not push enough to us
in the initial open to meet it, and its not actually our problem if
they don't.
Further, we used our own fee, instead of the channel's actual fee,
to calculate fee affordability of the initial commitment
transaction.
We resolve both issues here, rewriting the combined affordability
check conditionals in inbound channel open handling and adding a
fee affordability check for outbound channels as well.
The prior code may have allowed a counterparty to start the channel
with "no punishment" states - violating the reason for the reserve
threshold.
Instead of magic hard-coded constants, its better for tests to
derive the values used so that they change if constants are changed
and so that it is easier to re-derive constants in the future as
needed.
This may avoid risk of bugs in the future as it requires the caller
to think about the fee being used, not just blindly use the current
(committed) channel feerate.
In upcoming commits, we'll be making the payment secret and payment hash/preimage
derivable from info about the payment + a node secret. This means we don't
need to store any info about incoming payments and can eventually get rid of the
channelmanager::pending_inbound_payments map.
Traits in top-level modules is somewhat confusing - generally
top-level modules are just organizational modules and don't contain
things themselves, instead placing traits and structs in
sub-modules. Further, its incredibly awkward to have a `scorer`
sub-module, but only have a single struct in it, with the relevant
trait it is the only implementation of somewhere else. Not having
`Score` in the `scorer` sub-module is further confusing because
it's the only module anywhere that references scoring at all.
Sending HTLCs which are any greater than a very small fraction of the
channel size tend to fail at a much higher rate. Thus, by default
we start applying a penalty at only 1/8th the channel size and
increase it linearly as the amount reaches the channel's capacity,
20 msat per 1024th of the channel capacity.
This should allow `Score` implementations to make substantially
better decisions, including of the form "willing to pay X to avoid
routing over this channel which may have a high failure rate".
