ChannelManager docs aren't very approachable as they consist of a large
wall of texts without much direction. As a first step of improvement,
add sections to help delineate the existing text and make it easier to
scan.
This commit completes all of the groundwork necessary to decode incoming
`update_add_htlc` onions once they're fully committed to by both sides.
HTLCs are tracked in batches per-channel on the channel they were
received on. While this path is unreachable for now, until
`InboundHTLCResolution::Resolved` is replaced with
`InboundHTLCResolution::Pending`, it will allow us to obtain
`HTLCHandlingFailed` events for _any_ failed HTLC that comes across a
channel.
When decoding pending `update_add_htlc` onions, we may need to forward
HTLCs using `ChannelManager::forward_htlcs`. This may end up queueing a
`PendingHTLCsForwardable` event, but we're only decoding these pending
onions as a result of handling a `PendingHTLCsForwardable`, so we
shouldn't have to queue another one and wait for it to be handled. By
having a `forward_htlcs` variant that does not push the forward event,
we can ignore the forward event push when forwarding HTLCs which we just
decoded the onion for.
Since decoding pending `update_add_htlc` onions will go through the HTLC
forwarding path, we'll want to make sure we don't queue more events than
necessary if we have both HTLCs to forward/fail and pending
`update_add_htlc` onions to decode.
In the future, we plan to completely remove
`decode_update_add_htlc_onion` and replace it with a batched variant.
This refactor, while improving readability in its current form, does not
feature any functional changes and allows us to reuse the incoming HTLC
acceptance checks in the batched variant.
This simplifies the failure path by allowing us to return the general
error code for a failure, which we can then amend based on whether it
was for a phantom forward.
In the future, we plan to complete remove `decode_update_add_htlc_onion`
and replace it with a batched variant. This refactor, while improving
readability in its current form, does not feature any functional changes
and allows us to reuse most of the logic in the batched variant.
In the future, we plan to complete remove `decode_update_add_htlc_onion`
and replace it with a batched variant. This refactor, while improving
readability in its current form, does not feature any functional changes
and allows us to reuse most of the logic in the batched variant.
In the future, we plan to complete remove `decode_update_add_htlc_onion`
and replace it with a batched variant. This refactor, while improving
readability in its current form, does not feature any functional changes
and allows us to reuse most of the logic in the batched variant.
The existing variants do not cover such case as we previously never
surfaced `HTLCHandlingFailed` events for HTLCs that we failed back with
`UpdateFailMalformedHTLC` due to an invalid onion packet.
We plan to decode the onions of these `update_add_htlc`s as part of the
HTLC forwarding flow (i.e., `process_pending_htlc_forwards`), so we'll
need to track them per-channel at the `ChannelManager` level.
`htlc_forwards` only returns a `Some` value from
`handle_channel_resumption` if we provide it a non-empty
`pending_forwards`. Since we don't, we'll never have a value to handle.
This commit serves as a stepping stone to moving towards resolving HTLCs
once the HTLC has been fully committed to by both sides.
Currently, we decode HTLC onions immediately upon receiving an
`update_add_htlc`. Doing so determines what we should do with the HTLC:
forward it, or immediately fail it back if it cannot be accepted. This
action is tracked until the HTLC is fully committed to by both sides,
and a new commitment in the latter case is proposed to fully remove the
HTLC. While this has worked so far, it has some minor privacy
implications, as forwarding/failing back do not go through the usual
`PendingHTLCsForwardable` flow. It also presents issues with the
quiescence handshake, as failures through this path do not go through
the holding cell abstraction, leading to a potential violation of the
handshake by sending an `update_fail_*` after already having sent
`stfu`.
Since `pending_inbound_htlcs` are written pre-TLVs, we introduce a new
serialization version in which we change the `PendingHTLCStatus`
serialization of
`InboundHTLC::AwaitingRemoteRevokeToRemove/AwaitingRemovedRemoteRevoke`
to be an option instead. We'll still write it as the current version
(`MIN_SERIALIZATION_VERSION`), but we'll support reading the new version
to allow users to downgrade back to this commit.
We add new macro alternatives to
impl_writeable_for_vec/impl_readable_for_vec that add a length prefix to
each element in the `Vec`. This is intended to be used over the existing
macros when attempting to serialize a `Vec` with elements of variable
lengths.
We can't always assume that we're done reading after using a
FixedLengthReader. In some cases, we may need to read a set of
length-prefixed objects one at a time, and we'd like to do so without
incurring an additional allocation by reading a number of bytes first to
then deserialize them.
Replace instance of ChannelManager in BackgroundProcessor and in
Persister with AChannelManager. This reduces the number of type
parameters need in those types, which would need to be repeated in an
async version of Persister.
With its v24.02 release CLN made `GossipQueries` a required feature,
leading to a incompatibility between LDK and CLN when using
`IgnoringMessagHandler` as a `RoutingMessageHandler`, which is usually
the case when a node uses RGS.
To fix this issue, we let `IgnoringMessagHandler` signal `GossipQuery`
support, just to go ahead and ignore every gossip message the peer will
send us. While this is nonsensical and still might result in some
unnecessary bandwidth wasted, we have to do something to fix the
incompatibility.
Before a force closure from timed out HTLCs was treated the same as when
the user manually force closed the channel. This leads to various UX
issues. This adds a new `ClosureReason` called `HTLCsTimedOut` that
signifies that the closure was caused because the HTLCs timed out. To go
along with this, previously we'd always send "Channel force-closed" when
force closing the channel in the error message which was ambigous, now
we send the force closure reason so the peer can know why the channel
was closed.
Use OnionMessenger's public interface in tests whenever possible (i.e.,
when not using any intermediate_nodes in an OnionMessagePath. This
allows us to exercise DefaultMessageRouter, and, in particular that a
path can be found for an unannounced sender when its in the introduction
node.
DefaultMessageRouter will form an OnionMessagePath from a BlindedPath
where the sender is the introduction node but only if the sender is
announced. If the sender is unannounced, then DefaultMessageRouter will
fail. While DefaultMessageRouter will only create a blinded path with an
announced introduction node, it may receive one where the introduction
node is unannounced. Don't return an error in this case, as the
OnionMessenger can advance the blinded path by one hop.
This may occur when two nodes have an unannounced channel and one (the
offer creator) wants to use it for payments without an intermediary node
and without putting its node id in the offer.
