Now that we guarantee `claim_payment` will always succeed we have
to let the user know what the deadline is. We still fail payments
if they haven't been claimed in time, which we now expose in
`PaymentClaimable`.
There's no reason to hold a lock on `per_peer_state` while we're
claiming from a since-closed channel via a `ChannelMonitorUpdate`,
which we stop doing here.
`handle_error` must be called without `per_peer_state` mutex or
`pending_events` mutex locks held or we may risk deadlocks.
Previously we checked this in debug builds in the error path, but
not in the success path.
As it turns out, `funding_transaction_generated`'s error path does
hold a `per_peer_state` lock, which we fix here as well as move the
tests to happen unconditionally.
This passes the new `RecipientOnionFields` through the internal
sending APIs, ensuring we have access to the full struct when we
go to construct the sending onion so that we can include any new
fields added there.
While most lightning nodes don't (currently) support providing a
payment secret or payment metadata for spontaneous payments,
there's no specific technical reason why we shouldn't support
sending those fields to a recipient.
Further, when we eventually move to allowing custom TLV entries in
the recipient's onion TLV stream, we'll want to support it for
spontaneous payments as well.
Here we simply add the new `RecipientOnionFields` struct as an
argument to the spontaneous payment send methods. We don't yet
plumb it through the payment sending logic, which will come when we
plumb the new struct through the sending logic to replace the
existing payment secret arguments.
This moves the public payment sending API from passing an explicit
`PaymentSecret` to a new `RecipientOnionFields` struct (which
currently only contains the `PaymentSecret`). This gives us
substantial additional flexibility as we look at add both
`PaymentMetadata`, a new (well, year-or-two-old) BOLT11 invoice
extension to provide additional data sent to the recipient.
In the future, we should also add the ability to add custom TLV
entries in the `RecipientOnionFields` struct.
Many of the fields in `HTLCSource::OutboundRoute` are used to
rebuild the pending-outbound-payment map on reload if the
`ChannelManager` was not serialized though `ChannelMonitor`(s)
were after an HTLC was sent. As of 0.0.114, however, such payments
are not retryable without allowing them to fail and doing a full,
fresh, send.
Thus, some of the fields can be safely removed - we only really
care about having enough information to provide the user a failure
event, not being able to retry.
Here we drop one such field - the `payment_secret`, making our
`ChannelMonitorUpdate`s another handful of bytes smaller.
Previously, LDK would refuse to claim a payment if a channel on
which the payment was received had been closed between when the
HTLC was received and when we went to claim it. This makes sense in
the payment case - why pay an on-chain fee to claim the HTLC when
presumably the sender may retry later. Long ago it also reduced
total code in the claim pipeline.
However, this doesn't make sense if you're trying to do an atomic
swap or some other protocol that requires atomicity with some other
action - if your money got claimed elsewhere you need to be able to
claim the HTLC in lightning no matter what. Further, this is an
over-optimization - there should be a very, very low likelihood
that a channel closes between when we receive the last HTLC for a
payment and the user goes to claim the payment. Since we now have
code to handle this anyway we should allow it.
Fixes#2017.
Currently, users don't have good way of being notified when channel open
negotiations have succeeded and new channels are pending confirmation on
chain. To this end, we add a new `ChannelPending` event that is emitted
when send or receive a `funding_signed` message, i.e., at the last
moment before waiting for the confirmation period.
We track whether the event had previously been emitted in `Channel` and
remove it from `internal_funding_created` entirely. Hence, we now
only emit the event after ChannelMonitorUpdate completion, or upon
channel reestablish. This mitigates a race condition where where we
wouldn't persist the event *and* wouldn't regenerate it on restart,
therefore potentially losing it, if async CMU wouldn't complete before
ChannelManager persistence.
In `no-std`, we exposed `wait` functions which rely on a dummy
`Condvar` which never actually sleeps. This is somwhat nonsensical,
not to mention confusing to users. Instead, we simply remove the
`wait` methods in `no-std` builds.
Rather than having three ways to await a `ChannelManager` being
persistable, this moves to just exposing the awaitable `Future` and
having sleep functions on that.
If routing nodes take less fees and pay the final node more than
`amt_to_forward`, the receiver may see that `total_msat` has been met
before all of the sender's intended HTLCs have arrived. The receiver
may then prematurely claim the payment and release the payment hash,
allowing routing nodes to claim the remaining HTLCs. Using the onion
value `amt_to_forward` to determine when `total_msat` has been met
allows the sender to control the set total.
Final nodes previously had stricter requirements on HTLC contents
matching onion value compared to intermediate nodes. This allowed
for probing, i.e. the last intermediate node could overshoot the
value by a small amount and conclude from the acceptance or rejection
of the HTLC whether the next node was the destination. This also
applies to the msat amount, however this change was already present.
While retrying a failed path of an MPP, a node may want to overshoot
the `total_msat` in order to use a path with an `htlc_minimum_msat`
greater than the remaining value being sent. This commit no longer
fails MPPs that overshoot the `total_msat`, however it does fail
HTLCs with the same payment hash that are received *after* a
payment has become claimable.
This is pre-work for allowing nodes to overshoot onion values and
changing validation for MPP completion. This adds a field to
`ClaimableHTLC` that is separate from the onion values, which
represents the actual received amount reported in `PaymentClaimable`
which is what we want to validate against when a user goes to claim.
`ChannelMonitorUpdate`s are our most size-sensitive objects - they
are the minimal objects which need to be written to disk on each
commitment update. Thus, we should be careful to ensure we don't
pack too much extraneous information into each one.
Here we add future support for removing the per-HTLC explicit
`Option<Signature>` and `HTLCInCommitmentUpdate` for non-dust HTLCs
in holder commitment tx updates, which are redundant with the
`HolderCommitmentTransaction`.
While we cannot remove them entirely as previous versions rely on
them, adding support for filling in the in-memory structures from
the redundant fields will let us remove them in a future version.
We also add test-only generation logic to test the new derivation.
This is largely motivated by some follow-up work for anchors that will
introduce an event handler for `BumpTransaction` events, which we can
now include in this new top-level `events` module.
This results in a new, potentially redundant, `ChannelMonitorUpdate`
that must be applied to `ChannelMonitor`s to broadcast the holder's
latest commitment transaction.
This is a behavior change for anchor channels since their commitments
may require additional fees to be attached through a child anchor
transaction. Recall that anchor transactions are only generated by the
event consumer after processing a `BumpTransactionEvent::ChannelClose`
event, which is yielded after applying a
`ChannelMonitorUpdateStep::ChannelForceClosed` monitor update. Assuming
the node operator is not watching the mempool to generate these anchor
transactions without LDK, an anchor channel which we had to fail when
deserializing our `ChannelManager` would have its commitment transaction
broadcast by itself, potentially exposing the node operator to loss of
funds if the commitment transaction's fee is not enough to be accepted
into the network's mempools.
While we already provide a `list_channels` method, it could result in
quite a large `Vec<ChannelDetails>`. Here, we provide the means to query
our channels by `counterparty_node_id` and DRY up the code.
`FaliureCode` is a trivial enum with no body, so we shouldn't be
passing it by reference. Its sufficiently strange that the Java
bindings aren't happy with it, which is fine, we should just fix it
here.
When we receive an update_fulfill_htlc message, we immediately try
to "claim" the HTLC against the HTLCSource. If there is one, this
works great, we immediately generate a `ChannelMonitorUpdate` for
the corresponding inbound HTLC and persist that before we ever get
to processing our counterparty's `commitment_signed` and persisting
the corresponding `ChannelMonitorUpdate`.
However, if there isn't one (and this is the first successful HTLC
for a payment we sent), we immediately generate a `PaymentSent`
event and queue it up for the user. Then, a millisecond later, we
receive the `commitment_signed` from our peer, removing the HTLC
from the latest local commitment transaction as a side-effect of
the `ChannelMonitorUpdate` applied.
If the user has processed the `PaymentSent` event by that point,
great, we're done. However, if they have not, and we crash prior to
persisting the `ChannelManager`, on startup we get confused about
the state of the payment. We'll force-close the channel for being
stale, and see an HTLC which was removed and is no longer present
in the latest commitment transaction (which we're broadcasting).
Because we claim corresponding inbound HTLCs before updating a
`ChannelMonitor`, we assume such HTLCs have failed - attempting to
fail after having claimed should be a noop. However, in the
sent-payment case we now generate a `PaymentFailed` event for the
user, allowing an HTLC to complete without giving the user a
preimage.
Here we address this issue by storing the payment preimages for
claimed outbound HTLCs in the `ChannelMonitor`, in addition to the
existing inbound HTLC preimages already stored there. This allows
us to fix the specific issue described by checking for a preimage
and switching the type of event generated in response. In addition,
it reduces the risk of future confusion by ensuring we don't fail
HTLCs which were claimed but not fully committed to before a crash.
It does not, however, full fix the issue here - because the
preimages are removed after the HTLC has been fully removed from
available commitment transactions if we are substantially delayed
in persisting the `ChannelManager` from the time we receive the
`update_fulfill_htlc` until after a full commitment signed dance
completes we may still hit this issue. The full fix for this issue
is to delay the persistence of the `ChannelMonitorUpdate` until
after the `PaymentSent` event has been processed. This avoids the
issue entirely, ensuring we process the event before updating the
`ChannelMonitor`, the same as we ensure the upstream HTLC has been
claimed before updating the `ChannelMonitor` for forwarded
payments.
The full solution will be implemented in a later work, however this
change still makes sense at that point as well - if we were to
delay the initial `commitment_signed` `ChannelMonitorUpdate` util
after the `PaymentSent` event has been processed (which likely
requires a database update on the users' end), we'd hold our
`commitment_signed` + `revoke_and_ack` response for two DB writes
(i.e. `fsync()` calls), making our commitment transaction
processing a full `fsync` slower. By making this change first, we
can instead delay the `ChannelMonitorUpdate` from the
counterparty's final `revoke_and_ack` message until the event has
been processed, giving us a full network roundtrip to do so and
avoiding delaying our response as long as an `fsync` is faster than
a network roundtrip.
