In preparation for the next commit which will remove the
`*LightningNode` from the `ChannelEdgePolicy` struct,
`FetchLightningNode` is modified to take in an optional transaction so
that it can be utilised in places where a transaction exists.
Having a `ForEachChannel` method on the `LightningNode` struct itself
results in a `kvdb.Backend` object needing to be stored within the
LightningNode struct. In this commit, this method is replaced with a
`ForEachNodeChannel` method on the `ChannelGraph` struct will perform
the same function without needing the db pointer to be stored within the
LightningNode. This change, the LightningNode struct more closely
represents the schema on disk.
The existing `ForEachNodeChannel` method on `ChannelGraph` is renamed to
`ForEachNodeDirectedChannel`. It performs a slightly different function
since it's call-back operates on Cached policies.
This commit updates route construction to backfill the fields
required for payment to blinded paths and set amount to forward
and expiry fields to zero for intermediate hops (as is instructed
in the route blinding specification).
We could attempt to do this in the first pass, but that loop
relies on fields like amount to forward and expiry to calculate
each hop backwards, so we keep it simple (stupid) and post
processes the blinded portion, since it's computationally cheap
and more readable.
Add the option to include a blinded route in a route request (exclusive
to including hop hints, because it's incongruous to include both), and
express the route as a chain of hop hints.
Using a chain of hints over a single hint to represent the whole path
allows us to re-use our route construction to fill in a lot of the
path on our behalf.
This commit introduces a single struct to hold all of the parameters
that are passed to FindRoute. This cleans up an already overloaded
function signature and prepares us for handling requests with blinded
routes where we need to perform some additional processing on our
para (such as extracting the target node from the blinded path).
When we introduce blinded routes, some of our hops are expected
to have zero amounts to forward in their hop payload. This commit
updates our hop fee logic to attribute the full blinded route's
fees to the introduction node. We can't actually know where/how
these fees are distributed, so we collect them all at the
introduction node.
With the addition of blinded routes, we now need to account for the
possibility that intermediate nodes payloads will not have an amount
and expiry set because that information is provided by the recipient
encrypted data blob. This commit updates our payload packing to only
optionally include those fields.
This commit adds the encrypted_data, blinding_point and total_amt_msat
tlvs to the known set of even tlvs for the onion payload. These TLVs
are added in two places (the onion payload and hop struct) because
lnd uses the same set of TLV types for both structs (and they
inherently represent the same thing).
Note: in some places, unit tests intentionally mimic the style
of older tests, so as to be more consistently readable.
This commit adds a representation of blinded payments, which include a
blinded path and aggregate routing parameters to be used in payment to
the path.
This commit refactors the params used in lifecycle to prefer
`HTLCAttempt` over `HTLCAttemptInfo`. This change is needed as
`HTLCAttempt` also wraps settled and failure info, which is useful in
the following commits.
This commit turns `MPPayment` into an interface inside `routing`. Having
this interface gives us the benefit to write more granular unit tests
inside payment lifecycle. As seen from the modified unit tests, several
hacky ways of testing the `SendPayment` method is now replaced by a mock
over `MPPayment`.
This commit adds a new method, `NeedWaitAttempts`, to properly decide
whether we need to wait for the outcome of htlc attempts based on the
payment's current state.
This commit moves the struct `paymentState` used in `routing` into
`channeldb` and replaces it with `MPPaymentState`. In the following
commit we'd see the benefit, that we don't need to pass variables back
and forth between the two packages. More importantly, this state is put
closer to its origin, and is strictly updated whenever a payment is read
from disk. This approach is less error-prone comparing to the previous
one, which both the `payment` and `paymentState` need to be updated at
the same time to make sure the data stay consistant in a parallel
environment.
This commit moves the creations of hop and htlcAdd message from
`createNewPaymentAttempt` to `sendPaymentAttempt` to clean up the code
and further pave the way to decomposite the lifecycle.
This commit applies the new method `Terminated`. A side effect from
using this method is, we can now save one query `fetchPayment` inside
`FetchInFlightPayments`.
This commit adds a new payment status, `StatusInitiated`, to properly
represent the state where a payment is newly created without attempting
any HTLCs. Since the `PaymentStatus` is a memory representation of a
given payment's status, the enum used for the statuses are directly
updated.
In this commit, we carry out a new notion introduced during a recent
spec meeting to use a feature bit plus 100 before the feature has been
finalized in the spec.
We split into the Final and Staging bits.
In this commit, we start to set _internally_ a new feature bit in the
channel announcements we generate. As these taproot channels can only be
unadvertised, this will never actually leak to the public network. The
funding manager will then set this field to allow the router to properly
validate these channels.
In this commit, we update the Sig type to support ECDSA and schnorr
signatures. We need to do this as the HTLC signatures will become
schnorr sigs for taproot channels. The current spec draft opts to
overload this field since both the sigs are actually 64 bytes in length.
The only consideration with this move is that callers need to "coerce" a
sig to the proper type if they need schnorr signatures.
In this commit, we eliminate some code duplication by removing the old
`HashMutex` struct as it just duplicates all the code with a different
type (uint64 and hash). We then make the main Mutex struct take a type
param, so the key can be parametrized when the struct is instantiated.
This commit adds a a new `MarshalOutPoint` helper in the `lnrpc` package
that can be used to convert a `wire.Outpoint` to an `lnrpc.Outpoint`.
By using this helper, we are less likely to forget to populate both the
string and byte form of the TXID.
The process how we calculate a total probability from the direct and
node probability is modified to give more importance to the direct
probability.
This is important if we know about a recent failure. We should not try
to send over this channel again if we know we can't. Otherwise this can
lead to infinite retrials over the channel, when the probability is
pinned at high probabilities by the other node results.
Having a capacity available is important for liquidity estimation.
* We add a dummy capacity to hop hints. Hop hints specify neither the
capacity nor a maxHTLC size, which is why we assume the channel to
have a high capacity relative to the amount we send.
* We add a capacity to local edges. These channels should always have a
capacity associated with them, even in the neutrino case (a fallback
to maxHTLC is not necessary). This is just for completeness, as the
probability calculation for local channels is done separately.
* The maximal reduction in the probability is limited to 0.5 (previously
~0.05), such that we don't get too low apriori probabilities.
Otherwise, this may lead to a too strong selection of large (and maybe
expensive) channels. A two-hop path would get total probability
penalties of:
- 1000PPM/(0.6*0.6) = 2778 PPM in the unsaturated case
- 1000PPM/(0.6*(0.6*0.5)) = 5556 PPM in the saturated case, where the
second hop is saturated
The difference in PPM of 2778 PPM should be enough to bias towards the
first path.
* The smearing factor is reduced. Previously we had to keep a higher
smearing factor in order to make the capacity factor not go to zero
for high amounts, to still give a fully saturated channel a chance.
This is not needed anymore due to the capping to 0.5. A lower value of
the smearing factor lets us more precisely choose a capacity fraction
and the capacity factor is more neutral when it comes to intermediate
amounts.
We set a conservative default value for the capacity fraction, which
still has the effect of discarding exhausted channels, giving a
noticeable effect when about 90% of the capacity is being used.
We make the capacity factor configurable via an lnd.conf routerrpc
apriori parameter. The capacity factor trades off increased success
probability with a reduced set of channel candidates, which may lead to
increased fees. To let users choose whether the factor is active or not,
we add a config setting where a capacity fraction of 1.0 disables the
factor. We limit the capacity fraction to values between 0.75 and 1.0.
Lower values may discard too many channels.
We require channel updates to have the max HTLC message flag set.
Several flows need to pass that check before channel updates are
forwarded to peers:
* after channel funding: `addToRouterGraph`
* after receiving channel updates from a peer:
`ProcessRemoteAnnouncement`
* after we update channel policies: `PropagateChanPolicyUpdate`
