This commit extends the link with a new synchronous delivery point for
local UpdateAddHTLC messages. The switch method SendHTLC is updated to
use this delivery point and thereby becomes a synchronous call.
For MPP payments, synchronous hand-off is important. Otherwise the next
pathfinding round could start without the channel balance updated yet.
This commit moves the current logic for sending failures out of the link
and into the mailbox in preparation for our failing delayed htlcs. We do
so because the mailbox may need to fail packets while the link is
offline, and needs to be able to complete the task without member
methods on the link.
This commit changes the switch to only log an error if update_fail_htlc
comes in and closeCircuit returns ErrUnknownCircuit. Rationale
being that only settles should hit this code path, anything else
is a result of a link flap and should be treated as an error.
Add notifications for local initiated sends settles and forwarding
failures. As with link failures, local send settles and forwarding
failures are reported directly to the router so must have their own
notification handling.
Notify link failures for our own payments. Separate handling code is
required for local payment link failures because we do not pass these
failures back through the switch (like we do for link failures for
forwards), but rather send them straight back to the router. Our own
sends have the payment ID saved in the incoming htlc ID of the packet's
incoming circuit. This change replaces that value with for the sake
of consistent notifying of sends and receives from our node.
This commit sets more fields on the htlcPacket created to fail adding
a htlc packet to the switch for notification purposes. This new data is
copied by value from the original packet. The packet is then failed
back to the peer that forwarded us the packet, which is handled by
handledownstream packet. The values added to the packet are not used
in the handling of a failed packet.
In this commit, a htlcNotifier interface is added to allow for easy
unit testing. Instances of the HtlcNotifier are added to the server,
switch and link.
This commit enables the user to specify he is not interested in
automatically close channels with pending payments that their
corresponding htlcs have timed-out.
By requiring a configurable grace period uptime of our node
before closing such channels, we give a chance to the other node to
properly cancel the htlc and avoid unnecessary on-chain transaction.
In mobile it is very important for the user experience as otherwise
channels will be force closed more frequently.
This commit adds a linkError field to track the value of failures
which occur at our node. This field is set when local payments or
multi hop htlcs fail in the switch or on our outgoing link. This
addition is required for the addition of a htlc notifier which will
notify these failures in handleDownstreamPacket.
The passing of link error to failAddPacket removes the need for an
additional error field, because the link error's failure detail will
contain any additional metadata. In the places where the failure detail
does not cover all the metadata that was previously supplied by addr
err, the error is logged before calling failAddPacket so that this
change does not reduce the amount of information we log.
Add a FailureDetail interface which allows us have different kinds of
failures for link errors. This interface will be used to cover failures
that occur when on invoice payment, because the errors have already
been enumerated in the invoices package.
Rename FailureDetail in a separate commit so that a FailureDetail
interface can be introduced in the following commit.
OutgoingFailureOnionDecode is renamed to OutgoingFailureDecodeError
to specifically indicate that we could not decode the wire
failure that our payment experienced.
Add a CheckCircularForward function which detects packets which are
forwards over the same incoming and outgoing link, and errors if the
node is configured to disallow forwards of this nature. This check is
added to increase the cost of a liquidity lockup attack, because it
increases the length of the route required to lock up an individual
node's bandwidth. Since nodes are currently limited to 20 hops,
increasing the length of the route needed to lock up capital increases
the number of malicious payments an attacker will have to route, which
increases the capital requirement of the attack overall.
Update the ChannelLink interface to specifically
return the LinkError struct. This error implements
the ClearTextError interface, so will be picked
up as a routing realted error by the router.
With LinkErrors implemented, the switch now
returns a LinkError for all failures on our
incoming/outgoing link and ForwardingError when
the failure occurs down the line.
Add a constructor for the creation of forwarding errors.
A special constructor is added for the case where we have
an unknown wire failure, and must set a nil failure message.
This commit is adapted from @Bluetegu's original
pull request #1462.
This commit reads an optional address to pay funds out to
from a user iniitiated close channel address. If the channel
already has a shutdown script set, the request will fail if
an address is provided. Otherwise, the cooperative close will
pay out to the address provided.
In this commit, we create a new chainfee package, that houses all fee
related functionality used within the codebase. The creation of this new
package furthers our long-term goal of extracting functionality from the
bloated `lnwallet` package into new distinct packages. Additionally,
this new packages resolves a class of import cycle that could arise if a
new package that was imported by something in `lnwallet` wanted to use
the existing fee related functions in the prior `lnwallet` package.
In the scenario where the requested channel does not have enough balance
and another channel towards the same node generates a different failure,
we erroneously returned UnknownNextPeer instead of the expected
TemporaryChannelFailure.
This commit rewrites the non-strict forwarding logic in the switch to
return the proper failure message. Part of this is moving the link
balance check inside the link.
The policy update logic that resided part in the gossiper and
part in the rpc server is extracted into its own object.
This prepares for additional validation logic to be added for policy
updates that would otherwise make the gossiper heavier.
It is also a small first step towards separation of our own channel data
from the rest of the graph.
Since we will now wait to deliver the event after channel reestablish,
notifying when the link is added to the switch will no longer be
sufficient. Later, we will add receiving reestablish as an additional
requirement for EligibleToForward returning true.
The inactive ntfn is also moved, to ensure that we don't fire inactive
notifications if no corresponding active notification was sent.
In this commit, we fix a bug where if a user updates a forwarding policy to be
zero, the update will be applied to the policy correctly on-disk, but not
in-memory.
We solve this issue by having the gossiper return the list of on-disk updated
policies and passing these policies to the switch, so the switch can assume
that zero-valued fields are intentional and not just uninitialized.
htlcs
config: Adding RejectHTLC field in config struct
This commit adds a RejectHTLC field in the config struct in config.go.
This allows the user to run lnd as a node that does not accept onward
HTLCs.
htlcswitch/switch: Adding a field RejectHTLC to the switch config
This commit adds a field RejectHTLC to the switch config. When the
switch receives an HTLC it will check this flag and if the HTLC is not
from the source hop, the HTLC will be rejected.
htlcswitch/switch: adding check for RejectHTLC flag and incomingChanID
This commit adds a check when receiving UpdateAddHTLC. The check looks
for the RejectHTLC flag set and whether the HTLC is from the sourceHop
(the local switch). If the HTLC is not from the sourceHop, then we
reject the HTLC and return a FailChannelDisabled error.
server: adding RejectHTLC field to initialization of switch
lnd_test: adding test for RejectHTLC
This commit adds a test which tests that a node with the --rejecthtlc
flag will reject any onward HTLCs but still can receive direct HTLCs and
can send HTLCs.
This commit makes the outgoing link pipeline the settle to the
switch as soon as it receives it. Previously, it would wait for a
revocation before sending it, which caused increased latency on
payments as well as possibly never settling on the incoming link.
A duplicate settle is still sent to the switch, but it is handled
gracefully. A new AckEventTicker was added to the switch which
acknowledges any pending settle / fail entries in an outgoing
link's fwd pkgs in batch. This was needed in order to reduce the
number of db txn's which would have been incurred by acking whenever
we receive a duplicate settle without batching.
Methods on failure message types used to be defined on value receivers.
This allowed assignment of a failure message to ForwardingError both as
a value and as a pointer. This is error-prone, especially when using a
type switch.
In this commit the failure message methods are changed so that they
target pointer receivers.
Two instances where a value was assigned instead of a reference are
fixed.
In this commit we move handing the deobfuscator from the router to the
switch from when the payment is initiated, to when the result is
queried.
We do this because only the router can recreate the deobfuscator after a
restart, and we are preparing for being able to handle results across
restarts.
Since the deobfuscator cannot be nil anymore, we can also get rid of
that special case.
