Once ChannelManager supports payment retries, it will make more sense for its
current send_payment method to be named send_payment_with_route because
retrying should be the default. Here we get a head start on this by making the
rename in outbound_payment, but not changing the public interface yet.
This allows us to move a lot of outbound payment logic out of ChannelManager
and into the new outbound_payment module, and helps avoid growing
ChannelManager when we add retry logic to it in upcoming work.
We want to move all outbound payment-related things to this new module, to help
break up ChannelManager so future payment retries work doesn't increase the
size of ChannelManager.
If, after forwarding an intercepted payment to our counterparty, we
restart with a ChannelMonitor update having been persisted, but the
corresponding ChannelManager update not having been persisted,
we'll still have the intercepted HTLC in the
`pending_intercepted_htlcs` map on start (and potentially a pending
`HTLCIntercepted` event). This will cause us to allow the user to
handle the forwarded HTLC twice, potentially double-forwarding it.
This builds on 0bb87ddad7, which
provided a preemptive fix for the general relay case (though it was
not an actual issue at the time). We simply check for the HTLCs
having been forwarded on startup and remove them from the map.
Fixes#1858
If a user calls `abandon_payment`, then restarts without freshly
persisting the `ChannelManager`, the payment will still be pending
on restart. This was unclear from the docs (and the docs seemed to
imply otherwise). Because this doesn't materially impact the
usability of `abandon_payment` (users shouldn't be called
`retry_payment` on an abandoned one anyway), we simply document it.
Fixes#1804.
Currently `claim_funds` and `claim_funds_internal` call
`claim_funds_from_hop` and then surface and `Event` to the user
informing them of the forwarded/claimed payment based on it's
result. In both places we assume that a claim "completed" even if
a monitor update is being done async.
Instead, here we push that event generation through a
`MonitorUpdateCompletionAction` and a call to
`handle_monitor_update_completion_action`. This will allow us to
hold the event(s) until async monitor updates complete in the
future.
When `claim_funds` has to claim multiple HTLCs as a part of a
single MPP payment, it currently does so holding the
`channel_state` lock for the entire duration of the claim loop.
Here we swap that for taking the lock once for each HTLC. This
allows us to be more flexible with locks going forward, and
ultimately isn't a huge change - if our counterparty intends to
force-close a channel, us choosing to ignore it by holding the
`channel_state` lock for the duration of the claim isn't going to
result in a commitment update, it will just result in the preimage
already being in the `ChannelMonitor`.
Currently `claim_funds` does all HTLC claims in one `channel_state`
lock, ensuring that we always make claims from channels which are
open. It can thus avoid ever having to generate a
`ChannelMonitorUpdate` containing a preimage for a closed channel,
which we only do in `claim_funds_internal` (for forwarded payments).
In the next commit we'll change the locking of
`claim_funds_from_hop` so that `claim_funds` is no longer under a
single lock but takes a lock for each claim. This allows us to be
more flexible with locks going forward, and ultimately isn't a huge
change - if our counterparty intends to force-close a channel, us
choosing to ignore it by holding the `channel_state` lock for the
duration of the claim isn't going to result in a commitment update,
it will just result in the preimage already being in the
`ChannelMonitor`.
This adds a new enum, `MonitorUpdateCompletionAction` and a method
to execute the "actions". They are intended to be done once a
(potentially-async) `ChannelMonitorUpdate` persistence completes,
however this behavior will be implemented in a future PR. For now,
this adds the relevant infrastructure which will allow us to
prepare `claim_funds` for better monitor async handling.
In the next commits we'll move to generating `PaymentClaimed`
events while handling `ChannelMonitorUpdate`s rather than directly
in line. Thus, as a prerequisite, here we move to storing the info
required to generate the `PaymentClaimed` event in a separate map.
Note that while this does introduce a new map which is written as
an even value which users cannot opt out of, the map is only filled
in when users use the asynchronous `ChannelMonitor` updates and
after a future PR. As these are still considered beta, breaking
downgrades for such users is considered acceptable in the future PR
(which will likely be one LDK version later).
If we try to send any onion error with the `UPDATE` flag in
response to a phantom receipt, we should always swap it for
something generic that doesn't require a `channel_update` in it.
Here we use `temporary_node_failure`.
Test provided by Valentine Wallace <vwallace@protonmail.com>
When we receive a phantom HTLC with a bogus/modified CLTV, we
should fail back with `incorrect_cltv_expiry`, but that requires a
`channel_update`, which we cannot generate for a phantom HTLC which
has no corresponding channel. Thus, instead, we have to fall back
to `incorrect_cltv_expiry`.
Fixes#1879
The spec mandates that we copy the `sha256_hash_of_onion` field
from the `UpdateFailMalformedHTLC` message into the error message
we send back to the sender, however we simply ignored it. Here we
copy it into the message correctly.
This replaces `final_expiry_too_soon` with
`incorrect_or_unknown_payment` as was done in
https://github.com/lightning/bolts/pull/608. Note that the
rationale for this (that it may expose whether you are the final
recipient for the payment or not) does not currently apply to us -
we don't apply different final CLTV values to different payments.
However, we might in the future, and this will make us slightly
more consistent with other nodes.
Like the previous commit, here we update the update_fee+commit
logic to simply push the fee update into the holding cell and then
use the standard holding-cell-freeing codepaths to actually send
the commitment update. This removes a substantial amount of code,
reducing redundant codepaths and keeping channel state machine
logic in channel.rs.
We currently free the channel holding cells in
`get_and_clear_pending_msg_events`, blocking outbound messages
while we do so. This is fine, but may block the message pipeline
longer than we need to. In the next commit we'll push
timer-originating channel fee updates out through the holding cell
pipeline, leaning more on that freeing in the future.
Thus, to avoid a regression in message time, here we clear the
holding cell after processing all timer events. This also avoids
needing to change tests in the next commit.
When we batch HTLC updates, we currently do the explicit queueing
plus the commitment generation in the `ChannelManager`. This is a
bit strange as its ultimately really a `Channel` responsibility to
generate commitments at the correct time, with the abstraction
leaking into `ChannelManager` with the `send_htlc` and
`get_update_fail_htlc` method docs having clear comments about
how `send_commitment` MUST be called prior to calling other
`Channel` methods.
Luckily `Channel` already has an update queue - the holding cell.
Thus, we can trivially rewrite the batch update logic as inserting
the desired updates into the holding cell and then asking all
channels to clear their holding cells.
When a channel is force-closed, if a `ChannelMonitor` update is
completed but a `ChannelManager` persist has not yet happened,
HTLCs which were removed in the latest (persisted) `ChannelMonitor`
update will not be failed even though they do not appear in the
commitment transaction which went on chain. This is because the
`ChannelManager` thinks the `ChannelMonitor` is responsible for
them (as it is stale), but the `ChannelMonitor` has no knowledge of
the HTLC at all (as it is not stale).
The fix for this is relatively simple - we need to check for this
specific case and fail back such HTLCs when deserializing a
`ChannelManager`
If, after forwarding a payment to our counterparty, we restart with
a ChannelMonitor update having been persisted, but the
corresponding ChannelManager update was not persisted, we'll still
have the forwarded HTLC in the `forward_htlcs` map on start. This
will cause us to generate a (spurious) `PendingHTLCsForwardable`
event. However, when we go to forward said HTLC, we'll notice the
channel has been closed and leave it up to the `ChannelMontior` to
finalize the HTLC.
This is all fine today - we won't lose any funds, we'll just
generate an excess forwardable event and then fail to forward.
However, in the future when we allow for forward-time channel
changes this could break. Thus, its worth adding tests for this
behavior today, and, while we're at it, removing the spurious
forwardable HTLCs event.
Soon we're going to need to return an error when ChannelManager is unable to
find a route, so we'll need a way to distinguish between that and the user
supplying an invalid route.
