This is because we want the ability to retry completely failed
payments.
Upcoming commits will remove these payments on timeout to prevent
DoS issues
Also test that this removal allows retrying single-path payments
When we are prepared to forward HTLCs, we generate a
PendingHTLCsForwardable event with a time in the future when the
user should tell us to forward. This provides some basic batching
of forward events, improving privacy slightly.
After we generate the event, we expect users to spawn a timer in
the background and let us know when it finishes. However, if the
user shuts down before the timer fires, the user will restart and
have no idea that HTLCs are waiting to be forwarded/received.
To fix this, instead of serializing PendingHTLCsForwardable events
to disk while they're pending (before the user starts the timer),
we simply regenerate them when a ChannelManager is deserialized
with HTLCs pending.
Fixes#1042
We want to reuse send_payment internal functions for retries,
so some need to now be parameterized by PaymentId to avoid
generating a new PaymentId on retry
If a counterparty (or an old channel of ours) uses a non-segwit
script for their cooperative close payout, they may include an
output which is unbroadcastable due to not meeting the network dust
limit.
Here we check for this condition, force-closing the channel instead
if we find an output in the closing transaction which does not meet
the limit.
There is little reason for users to be paying out to non-Segwit
scripts when closing channels at this point. Given we will soon, in
rare cases, force-close during shutdown when a counterparty closes
to a non-Segwit script, we should also require it of our own users.
546 sat/vbyte is the current default dust limit on most
implementations, matching the network dust limit for P2SH outputs.
Implementations don't currently appear to send any larger dust
limits, and allowing a larger dust limit implies higher payment
failure risk, so we'd like to be as tight as we can here.
Associated types in C bindings is somewhat of a misnomer - we
concretize each trait to a single struct. Thus, different trait
implementations must still have the same type, which defeats the
point of associated types.
In this particular case, however, we can reasonably special-case
the `Infallible` type, as an instance of it existing implies
something has gone horribly wrong.
In order to help our bindings code figure out how to do so when
referencing a parent trait's associated type, we specify the
explicit type in the implementation method signature.
When we landed custom messages, we used the empty tuple for the
custom message type for `IgnoringMessageHandler`. This was fine,
except that we also implemented `Writeable` to panic when writing
a `()`. Later, we added support for anchor output construction in
CommitmentTransaction, signified by setting a field to `Some(())`,
which is serialized as-is.
This causes us to panic when writing a `CommitmentTransaction`
with `opt_anchors` set. Note that we never set it inside of LDK,
but downstream users may.
Instead, we implement `Writeable` to write nothing for `()` and use
`core::convert::Infallible` for the default custom message type as
it is, appropriately, unconstructable.
This also makes it easier to implement various things in bindings,
as we can always assume `Infallible`-conversion logic is
unreachable.
`wire::Type` is only (publicly) used as the `CustomMessage`
associated type in `CustomMessageReader`, where it has additional
trait bounds on `Debug` and `Writeable`. The documentation for
`Type` even mentions that you need to implement `Writeable` because
this is the one place it is used.
To make this more clear, we move the type bounds onto the trait
itself and not on the associated type.
This is also the only practical way to build C bindings for `Type`
as we cannot have a concrete, single, `Type` struct in C which only
optionally implements various subtraits, at least not without
runtime checking of the type bounds.
When we detect a channel `is_shutdown()` or call on it
`force_shutdown()`, we notify the user with a Event::ChannelClosed
informing about the id and closure reason.
The network serialization format for all messages was changed some
time ago to include a TLV suffix for all messages, however we never
bothered to implement it as there isn't a lot of use validating a
TLV stream with nothing to do with it. However, messages are
increasingly utilizing the TLV suffix feature, and there are some
compatibility concerns with messages written as a part of other
structs having their format changed (see previous commit).
Thus, here we go ahead and convert most message serialization to a
new macro which includes a TLV suffix after a series of fields,
simplifying several serialization implementations in the process.
Going forward, all lightning messages have a TLV stream suffix,
allowing new fields to be added as needed. In the P2P protocol,
messages have an explicit length, so there is no implied length in
the TLV stream itself. HTLCFailureMsg enum variants have messages
in them, but without a size prefix or any explicit end. Thus, if a
HTLCFailureMsg is read as a part of a ChannelManager, with a TLV
stream at the end, there is no way to differentiate between the end
of the message and the next field(s) in the ChannelManager.
Here we add two new variant values for HTLCFailureMsg variants in
the read path, allowing us to switch to the new values if/when we
add new TLV fields in UpdateFailHTLC or UpdateFailMalformedHTLC so
that older versions can still read the new TLV fields.
In order to avoid significant malloc traffic, messages previously
explicitly stated their serialized length allowing for Vec
preallocation during the message serialization pipeline. This added
some amount of complexity in the serialization code, but did avoid
some realloc() calls.
Instead, here, we drop all the complexity in favor of a fixed 2KiB
buffer for all message serialization. This should not only be
simpler with a similar reduction in realloc() traffic, but also
may reduce heap fragmentation by allocating identically-sized
buffers more often.
330 sat/vbyte, the current value, is not sufficient to ensure a
future segwit script longer than 32 bytes meets the dust limit if
used for a shutdown script. Thus, we can either check the value
on shutdown or we can simply require segwit outputs and require a
dust value of no less than 354 sat/vbyte.
We swap the minimum dust value to 354 sat/vbyte here, requiring
segwit scripts in a future commit.
See https://github.com/lightningnetwork/lightning-rfc/issues/905
In general, we should always allow users to query for how much is
currently in-flight being claimed on-chain at any time.
This does so by examining the confirmed claims on-chain and
breaking down what is left to be claimed into a new
`ClaimableBalance` enum.
Fixes#995.
PaymentFailed events contain an optional NetworkUpdate describing
changes to the NetworkGraph as conveyed by a node along a failed payment
path according to BOLT 4. An EventHandler should apply the update to the
graph so that future routing decisions can account for it.
Implement EventHandler for NetGraphMsgHandler to update NetworkGraph.
Previously, NetGraphMsgHandler::handle_htlc_fail_channel_update
implemented this behavior.
MessageSendEvent::PaymentFailureNetworkUpdate served as a hack to pass
an HTLCFailChannelUpdate from ChannelManager to NetGraphMsgHandler via
PeerManager. Instead, remove the event entirely and move the contained
data (renamed NetworkUpdate) to Event::PaymentFailed to be processed by
an event handler.
