9915780197

Committed 13 Jul 2024 12:30AM UTC coverage: 49.268% (-9.1%) from 58.413%

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Merge pull request #8653 from ProofOfKeags/fn-prim

DynComms [0/n]: `fn` package additions

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/routing/unified_edges.go

package routing

import (
        "math"

        "github.com/btcsuite/btcd/btcutil"
        "github.com/lightningnetwork/lnd/channeldb"
        "github.com/lightningnetwork/lnd/channeldb/models"
        "github.com/lightningnetwork/lnd/lntypes"
        "github.com/lightningnetwork/lnd/lnwire"
        "github.com/lightningnetwork/lnd/routing/route"
)

// nodeEdgeUnifier holds all edge unifiers for connections towards a node.
type nodeEdgeUnifier struct {
        // edgeUnifiers contains an edge unifier for every from node.
        edgeUnifiers map[route.Vertex]*edgeUnifier

        // sourceNode is the sender of a payment. The rules to pick the final
        // policy are different for local channels.
        sourceNode route.Vertex

        // toNode is the node for which the edge unifiers are instantiated.
        toNode route.Vertex

        // useInboundFees indicates whether to take inbound fees into account.
        useInboundFees bool

        // outChanRestr is an optional outgoing channel restriction for the
        // local channel to use.
        outChanRestr map[uint64]struct{}
}

// newNodeEdgeUnifier instantiates a new nodeEdgeUnifier object. Channel
// policies can be added to this object.
func newNodeEdgeUnifier(sourceNode, toNode route.Vertex, useInboundFees bool,
        outChanRestr map[uint64]struct{}) *nodeEdgeUnifier {

        return &nodeEdgeUnifier{
                edgeUnifiers:   make(map[route.Vertex]*edgeUnifier),
                toNode:         toNode,
                useInboundFees: useInboundFees,
                sourceNode:     sourceNode,
                outChanRestr:   outChanRestr,
        }
}

// addPolicy adds a single channel policy. Capacity may be zero if unknown
// (light clients). We expect a non-nil payload size function and will request a
// graceful shutdown if it is not provided as this indicates that edges are
// incorrectly specified.
func (u *nodeEdgeUnifier) addPolicy(fromNode route.Vertex,
        edge *models.CachedEdgePolicy, inboundFee models.InboundFee,
        capacity btcutil.Amount, hopPayloadSizeFn PayloadSizeFunc,
        blindedPayment *BlindedPayment) {

        localChan := fromNode == u.sourceNode

        // Skip channels if there is an outgoing channel restriction.
        if localChan && u.outChanRestr != nil {
                if _, ok := u.outChanRestr[edge.ChannelID]; !ok {
                        return
                }
        }

        // Update the edgeUnifiers map.
        unifier, ok := u.edgeUnifiers[fromNode]
        if !ok {
                unifier = &edgeUnifier{
                        localChan: localChan,
                }
                u.edgeUnifiers[fromNode] = unifier
        }

        // In case no payload size function was provided a graceful shutdown
        // is requested, because this function is not used as intended.
        if hopPayloadSizeFn == nil {
                log.Criticalf("No payloadsize function was provided for the "+
                        "edge (chanid=%v) when adding it to the edge unifier "+
                        "of node: %v", edge.ChannelID, fromNode)

                return
        }

        // Zero inbound fee for exit hops.
        if !u.useInboundFees {
                inboundFee = models.InboundFee{}
        }

        unifier.edges = append(unifier.edges, newUnifiedEdge(
                edge, capacity, inboundFee, hopPayloadSizeFn, blindedPayment,
        ))
}

// addGraphPolicies adds all policies that are known for the toNode in the
// graph.
func (u *nodeEdgeUnifier) addGraphPolicies(g routingGraph) error {
        cb := func(channel *channeldb.DirectedChannel) error {
                // If there is no edge policy for this candidate node, skip.
                // Note that we are searching backwards so this node would have
                // come prior to the pivot node in the route.
                if channel.InPolicy == nil {
                        return nil
                }

                // Add this policy to the corresponding edgeUnifier. We default
                // to the clear hop payload size function because
                // `addGraphPolicies` is only used for cleartext intermediate
                // hops in a route.
                inboundFee := models.NewInboundFeeFromWire(
                        channel.InboundFee,
                )

                u.addPolicy(
                        channel.OtherNode, channel.InPolicy, inboundFee,
                        channel.Capacity, defaultHopPayloadSize, nil,
                )

                return nil
        }

        // Iterate over all channels of the to node.
        return g.forEachNodeChannel(u.toNode, cb)
}

// unifiedEdge is the individual channel data that is kept inside an edgeUnifier
// object.
type unifiedEdge struct {
        policy      *models.CachedEdgePolicy
        capacity    btcutil.Amount
        inboundFees models.InboundFee

        // hopPayloadSize supplies an edge with the ability to calculate the
        // exact payload size if this edge would be included in a route. This
        // is needed because hops of a blinded path differ in their payload
        // structure compared to cleartext hops.
        hopPayloadSizeFn PayloadSizeFunc

        // blindedPayment if set, is the BlindedPayment that this edge was
        // derived from originally.
        blindedPayment *BlindedPayment
}

// newUnifiedEdge constructs a new unifiedEdge.
func newUnifiedEdge(policy *models.CachedEdgePolicy, capacity btcutil.Amount,
        inboundFees models.InboundFee, hopPayloadSizeFn PayloadSizeFunc,
        blindedPayment *BlindedPayment) *unifiedEdge {

        return &unifiedEdge{
                policy:           policy,
                capacity:         capacity,
                inboundFees:      inboundFees,
                hopPayloadSizeFn: hopPayloadSizeFn,
                blindedPayment:   blindedPayment,
        }
}

// amtInRange checks whether an amount falls within the valid range for a
// channel.
func (u *unifiedEdge) amtInRange(amt lnwire.MilliSatoshi) bool {
        // If the capacity is available (non-light clients), skip channels that
        // are too small.
        if u.capacity > 0 &&
                amt > lnwire.NewMSatFromSatoshis(u.capacity) {

                log.Tracef("Not enough capacity: amt=%v, capacity=%v",
                        amt, u.capacity)
                return false
        }

        // Skip channels for which this htlc is too large.
        if u.policy.MessageFlags.HasMaxHtlc() &&
                amt > u.policy.MaxHTLC {

                log.Tracef("Exceeds policy's MaxHTLC: amt=%v, MaxHTLC=%v",
                        amt, u.policy.MaxHTLC)
                return false
        }

        // Skip channels for which this htlc is too small.
        if amt < u.policy.MinHTLC {
                log.Tracef("below policy's MinHTLC: amt=%v, MinHTLC=%v",
                        amt, u.policy.MinHTLC)
                return false
        }

        return true
}

// edgeUnifier is an object that covers all channels between a pair of nodes.
type edgeUnifier struct {
        edges     []*unifiedEdge
        localChan bool
}

// getEdge returns the optimal unified edge to use for this connection given a
// specific amount to send. It differentiates between local and network
// channels.
func (u *edgeUnifier) getEdge(netAmtReceived lnwire.MilliSatoshi,
        bandwidthHints bandwidthHints,
        nextOutFee lnwire.MilliSatoshi) *unifiedEdge {

        if u.localChan {
                return u.getEdgeLocal(
                        netAmtReceived, bandwidthHints, nextOutFee,
                )
        }

        return u.getEdgeNetwork(netAmtReceived, nextOutFee)
}

// calcCappedInboundFee calculates the inbound fee for a channel, taking into
// account the total node fee for the "to" node.
func calcCappedInboundFee(edge *unifiedEdge, amt lnwire.MilliSatoshi,
        nextOutFee lnwire.MilliSatoshi) int64 {

        // Calculate the inbound fee charged for the amount that passes over the
        // channel.
        inboundFee := edge.inboundFees.CalcFee(amt)

        // Take into account that the total node fee cannot be negative.
        if inboundFee < -int64(nextOutFee) {
                inboundFee = -int64(nextOutFee)
        }

        return inboundFee
}

// getEdgeLocal returns the optimal unified edge to use for this local
// connection given a specific amount to send.
func (u *edgeUnifier) getEdgeLocal(netAmtReceived lnwire.MilliSatoshi,
        bandwidthHints bandwidthHints,
        nextOutFee lnwire.MilliSatoshi) *unifiedEdge {

        var (
                bestEdge     *unifiedEdge
                maxBandwidth lnwire.MilliSatoshi
        )

        for _, edge := range u.edges {
                // Calculate the inbound fee charged at the receiving node.
                inboundFee := calcCappedInboundFee(
                        edge, netAmtReceived, nextOutFee,
                )

                // Add inbound fee to get to the amount that is sent over the
                // local channel.
                amt := netAmtReceived + lnwire.MilliSatoshi(inboundFee)

                // Check valid amount range for the channel.
                if !edge.amtInRange(amt) {
                        log.Debugf("Amount %v not in range for edge %v",
                                netAmtReceived, edge.policy.ChannelID)

                        continue
                }

                // For local channels, there is no fee to pay or an extra time
                // lock. We only consider the currently available bandwidth for
                // channel selection. The disabled flag is ignored for local
                // channels.

                // Retrieve bandwidth for this local channel. If not
                // available, assume this channel has enough bandwidth.
                //
                // TODO(joostjager): Possibly change to skipping this
                // channel. The bandwidth hint is expected to be
                // available.
                bandwidth, ok := bandwidthHints.availableChanBandwidth(
                        edge.policy.ChannelID, amt,
                )
                if !ok {
                        log.Debugf("Cannot get bandwidth for edge %v, use max "+
                                "instead", edge.policy.ChannelID)
                        bandwidth = lnwire.MaxMilliSatoshi
                }

                // TODO(yy): if the above `!ok` is chosen, we'd have
                // `bandwidth` to be the max value, which will end up having
                // the `maxBandwidth` to be have the largest value and this
                // edge will be the chosen one. This is wrong in two ways,
                // 1. we need to understand why `availableChanBandwidth` cannot
                // find bandwidth for this edge as something is wrong with this
                // channel, and,
                // 2. this edge is likely NOT the local channel with the
                // highest available bandwidth.
                //
                // Skip channels that can't carry the payment.
                if amt > bandwidth {
                        log.Debugf("Skipped edge %v: not enough bandwidth, "+
                                "bandwidth=%v, amt=%v", edge.policy.ChannelID,
                                bandwidth, amt)

                        continue
                }

                // We pick the local channel with the highest available
                // bandwidth, to maximize the success probability. It can be
                // that the channel state changes between querying the bandwidth
                // hints and sending out the htlc.
                if bandwidth < maxBandwidth {
                        log.Debugf("Skipped edge %v: not max bandwidth, "+
                                "bandwidth=%v, maxBandwidth=%v",
                                edge.policy.ChannelID, bandwidth, maxBandwidth)

                        continue
                }
                maxBandwidth = bandwidth

                // Update best edge.
                bestEdge = newUnifiedEdge(
                        edge.policy, edge.capacity, edge.inboundFees,
                        edge.hopPayloadSizeFn, edge.blindedPayment,
                )
        }

        return bestEdge
}

// getEdgeNetwork returns the optimal unified edge to use for this connection
// given a specific amount to send. The goal is to return a unified edge with a
// policy that maximizes the probability of a successful forward in a non-strict
// forwarding context.
func (u *edgeUnifier) getEdgeNetwork(netAmtReceived lnwire.MilliSatoshi,
        nextOutFee lnwire.MilliSatoshi) *unifiedEdge {

        var (
                bestPolicy       *unifiedEdge
                maxFee           int64 = math.MinInt64
                maxTimelock      uint16
                maxCapMsat       lnwire.MilliSatoshi
                hopPayloadSizeFn PayloadSizeFunc
        )

        for _, edge := range u.edges {
                // Calculate the inbound fee charged at the receiving node.
                inboundFee := calcCappedInboundFee(
                        edge, netAmtReceived, nextOutFee,
                )

                // Add inbound fee to get to the amount that is sent over the
                // channel.
                amt := netAmtReceived + lnwire.MilliSatoshi(inboundFee)

                // Check valid amount range for the channel.
                if !edge.amtInRange(amt) {
                        log.Debugf("Amount %v not in range for edge %v",
                                amt, edge.policy.ChannelID)
                        continue
                }

                // For network channels, skip the disabled ones.
                edgeFlags := edge.policy.ChannelFlags
                isDisabled := edgeFlags&lnwire.ChanUpdateDisabled != 0
                if isDisabled {
                        log.Debugf("Skipped edge %v due to it being disabled",
                                edge.policy.ChannelID)
                        continue
                }

                // Track the maximal capacity for usable channels. If we don't
                // know the capacity, we fall back to MaxHTLC.
                capMsat := lnwire.NewMSatFromSatoshis(edge.capacity)
                if capMsat == 0 && edge.policy.MessageFlags.HasMaxHtlc() {
                        log.Tracef("No capacity available for channel %v, "+
                                "using MaxHtlcMsat (%v) as a fallback.",
                                edge.policy.ChannelID, edge.policy.MaxHTLC)

                        capMsat = edge.policy.MaxHTLC
                }
                maxCapMsat = lntypes.Max(capMsat, maxCapMsat)

                // Track the maximum time lock of all channels that are
                // candidate for non-strict forwarding at the routing node.
                maxTimelock = lntypes.Max(
                        maxTimelock, edge.policy.TimeLockDelta,
                )

                outboundFee := int64(edge.policy.ComputeFee(amt))
                fee := outboundFee + inboundFee

                // Use the policy that results in the highest fee for this
                // specific amount.
                if fee < maxFee {
                        log.Debugf("Skipped edge %v due to it produces less "+
                                "fee: fee=%v, maxFee=%v",
                                edge.policy.ChannelID, fee, maxFee)

                        continue
                }
                maxFee = fee

                bestPolicy = newUnifiedEdge(
                        edge.policy, 0, edge.inboundFees, nil,
                        edge.blindedPayment,
                )

                // The payload size function for edges to a connected peer is
                // always the same hence there is not need to find the maximum.
                // This also counts for blinded edges where we only have one
                // edge to a blinded peer.
                hopPayloadSizeFn = edge.hopPayloadSizeFn
        }

        // Return early if no channel matches.
        if bestPolicy == nil {
                return nil
        }

        // We have already picked the highest fee that could be required for
        // non-strict forwarding. To also cover the case where a lower fee
        // channel requires a longer time lock, we modify the policy by setting
        // the maximum encountered time lock. Note that this results in a
        // synthetic policy that is not actually present on the routing node.
        //
        // The reason we do this, is that we try to maximize the chance that we
        // get forwarded. Because we penalize pair-wise, there won't be a second
        // chance for this node pair. But this is all only needed for nodes that
        // have distinct policies for channels to the same peer.
        policyCopy := *bestPolicy.policy
        policyCopy.TimeLockDelta = maxTimelock
        modifiedEdge := newUnifiedEdge(
                &policyCopy, maxCapMsat.ToSatoshis(), bestPolicy.inboundFees,
                hopPayloadSizeFn, bestPolicy.blindedPayment,
        )

        return modifiedEdge
}

// minAmt returns the minimum amount that can be forwarded on this connection.
func (u *edgeUnifier) minAmt() lnwire.MilliSatoshi {
        min := lnwire.MaxMilliSatoshi
        for _, edge := range u.edges {
                min = lntypes.Min(min, edge.policy.MinHTLC)
        }

        return min
}

1	package routing
2
3	import (
4	"math"
5
6	"github.com/btcsuite/btcd/btcutil"
7	"github.com/lightningnetwork/lnd/channeldb"
8	"github.com/lightningnetwork/lnd/channeldb/models"
9	"github.com/lightningnetwork/lnd/lntypes"
10	"github.com/lightningnetwork/lnd/lnwire"
11	"github.com/lightningnetwork/lnd/routing/route"
12	)
13
14	// nodeEdgeUnifier holds all edge unifiers for connections towards a node.
15	type nodeEdgeUnifier struct {
16	// edgeUnifiers contains an edge unifier for every from node.
17	edgeUnifiers map[route.Vertex]*edgeUnifier
18
19	// sourceNode is the sender of a payment. The rules to pick the final
20	// policy are different for local channels.
21	sourceNode route.Vertex
22
23	// toNode is the node for which the edge unifiers are instantiated.
24	toNode route.Vertex
25
26	// useInboundFees indicates whether to take inbound fees into account.
27	useInboundFees bool
28
29	// outChanRestr is an optional outgoing channel restriction for the
30	// local channel to use.
31	outChanRestr map[uint64]struct{}
32	}
33
34	// newNodeEdgeUnifier instantiates a new nodeEdgeUnifier object. Channel
35	// policies can be added to this object.
36	func newNodeEdgeUnifier(sourceNode, toNode route.Vertex, useInboundFees bool,
37	outChanRestr map[uint64]struct{}) *nodeEdgeUnifier {	3✔
38		3✔
39	return &nodeEdgeUnifier{	3✔
40	edgeUnifiers: make(map[route.Vertex]*edgeUnifier),	3✔
41	toNode: toNode,	3✔
42	useInboundFees: useInboundFees,	3✔
43	sourceNode: sourceNode,	3✔
44	outChanRestr: outChanRestr,	3✔
45	}	3✔
46	}	3✔
47
48	// addPolicy adds a single channel policy. Capacity may be zero if unknown
49	// (light clients). We expect a non-nil payload size function and will request a
50	// graceful shutdown if it is not provided as this indicates that edges are
51	// incorrectly specified.
52	func (u *nodeEdgeUnifier) addPolicy(fromNode route.Vertex,
53	edge *models.CachedEdgePolicy, inboundFee models.InboundFee,
54	capacity btcutil.Amount, hopPayloadSizeFn PayloadSizeFunc,
55	blindedPayment *BlindedPayment) {	3✔
56		3✔
57	localChan := fromNode == u.sourceNode	3✔
58		3✔
59	// Skip channels if there is an outgoing channel restriction.	3✔
60	if localChan && u.outChanRestr != nil {	3✔
61	if _, ok := u.outChanRestr[edge.ChannelID]; !ok {	×
62	return	×
63	}	×
64	}
65
66	// Update the edgeUnifiers map.
67	unifier, ok := u.edgeUnifiers[fromNode]	3✔
68	if !ok {	6✔
69	unifier = &edgeUnifier{	3✔
70	localChan: localChan,	3✔
71	}	3✔
72	u.edgeUnifiers[fromNode] = unifier	3✔
73	}	3✔
74
75	// In case no payload size function was provided a graceful shutdown
76	// is requested, because this function is not used as intended.
77	if hopPayloadSizeFn == nil {	3✔
78	log.Criticalf("No payloadsize function was provided for the "+	×
79	"edge (chanid=%v) when adding it to the edge unifier "+	×
80	"of node: %v", edge.ChannelID, fromNode)	×
81		×
82	return	×
83	}	×
84
85	// Zero inbound fee for exit hops.
86	if !u.useInboundFees {	6✔
87	inboundFee = models.InboundFee{}	3✔
88	}	3✔
89
90	unifier.edges = append(unifier.edges, newUnifiedEdge(	3✔
91	edge, capacity, inboundFee, hopPayloadSizeFn, blindedPayment,	3✔
92	))	3✔
93	}
94
95	// addGraphPolicies adds all policies that are known for the toNode in the
96	// graph.
97	func (u *nodeEdgeUnifier) addGraphPolicies(g routingGraph) error {	3✔
98	cb := func(channel *channeldb.DirectedChannel) error {	6✔
99	// If there is no edge policy for this candidate node, skip.	3✔
100	// Note that we are searching backwards so this node would have	3✔
101	// come prior to the pivot node in the route.	3✔
102	if channel.InPolicy == nil {	3✔
103	return nil	×
104	}	×
105
106	// Add this policy to the corresponding edgeUnifier. We default
107	// to the clear hop payload size function because
108	// `addGraphPolicies` is only used for cleartext intermediate
109	// hops in a route.
110	inboundFee := models.NewInboundFeeFromWire(	3✔
111	channel.InboundFee,	3✔
112	)	3✔
113		3✔
114	u.addPolicy(	3✔
115	channel.OtherNode, channel.InPolicy, inboundFee,	3✔
116	channel.Capacity, defaultHopPayloadSize, nil,	3✔
117	)	3✔
118		3✔
119	return nil	3✔
120	}
121
122	// Iterate over all channels of the to node.
123	return g.forEachNodeChannel(u.toNode, cb)	3✔
124	}
125
126	// unifiedEdge is the individual channel data that is kept inside an edgeUnifier
127	// object.
128	type unifiedEdge struct {
129	policy *models.CachedEdgePolicy
130	capacity btcutil.Amount
131	inboundFees models.InboundFee
132
133	// hopPayloadSize supplies an edge with the ability to calculate the
134	// exact payload size if this edge would be included in a route. This
135	// is needed because hops of a blinded path differ in their payload
136	// structure compared to cleartext hops.
137	hopPayloadSizeFn PayloadSizeFunc
138
139	// blindedPayment if set, is the BlindedPayment that this edge was
140	// derived from originally.
141	blindedPayment *BlindedPayment
142	}
143
144	// newUnifiedEdge constructs a new unifiedEdge.
145	func newUnifiedEdge(policy *models.CachedEdgePolicy, capacity btcutil.Amount,
146	inboundFees models.InboundFee, hopPayloadSizeFn PayloadSizeFunc,
147	blindedPayment BlindedPayment) unifiedEdge {	3✔
148		3✔
149	return &unifiedEdge{	3✔
150	policy: policy,	3✔
151	capacity: capacity,	3✔
152	inboundFees: inboundFees,	3✔
153	hopPayloadSizeFn: hopPayloadSizeFn,	3✔
154	blindedPayment: blindedPayment,	3✔
155	}	3✔
156	}	3✔
157
158	// amtInRange checks whether an amount falls within the valid range for a
159	// channel.
160	func (u *unifiedEdge) amtInRange(amt lnwire.MilliSatoshi) bool {	3✔
161	// If the capacity is available (non-light clients), skip channels that	3✔
162	// are too small.	3✔
163	if u.capacity > 0 &&	3✔
164	amt > lnwire.NewMSatFromSatoshis(u.capacity) {	3✔
165		×
166	log.Tracef("Not enough capacity: amt=%v, capacity=%v",	×
167	amt, u.capacity)	×
168	return false	×
169	}	×
170
171	// Skip channels for which this htlc is too large.
172	if u.policy.MessageFlags.HasMaxHtlc() &&	3✔
173	amt > u.policy.MaxHTLC {	6✔
174		3✔
175	log.Tracef("Exceeds policy's MaxHTLC: amt=%v, MaxHTLC=%v",	3✔
176	amt, u.policy.MaxHTLC)	3✔
177	return false	3✔
178	}	3✔
179
180	// Skip channels for which this htlc is too small.
181	if amt < u.policy.MinHTLC {	6✔
182	log.Tracef("below policy's MinHTLC: amt=%v, MinHTLC=%v",	3✔
183	amt, u.policy.MinHTLC)	3✔
184	return false	3✔
185	}	3✔
186
187	return true	3✔
188	}
189
190	// edgeUnifier is an object that covers all channels between a pair of nodes.
191	type edgeUnifier struct {
192	edges []*unifiedEdge
193	localChan bool
194	}
195
196	// getEdge returns the optimal unified edge to use for this connection given a
197	// specific amount to send. It differentiates between local and network
198	// channels.
199	func (u *edgeUnifier) getEdge(netAmtReceived lnwire.MilliSatoshi,
200	bandwidthHints bandwidthHints,
201	nextOutFee lnwire.MilliSatoshi) *unifiedEdge {	3✔
202		3✔
203	if u.localChan {	6✔
204	return u.getEdgeLocal(	3✔
205	netAmtReceived, bandwidthHints, nextOutFee,	3✔
206	)	3✔
207	}	3✔
208
209	return u.getEdgeNetwork(netAmtReceived, nextOutFee)	3✔
210	}
211
212	// calcCappedInboundFee calculates the inbound fee for a channel, taking into
213	// account the total node fee for the "to" node.
214	func calcCappedInboundFee(edge *unifiedEdge, amt lnwire.MilliSatoshi,
215	nextOutFee lnwire.MilliSatoshi) int64 {	3✔
216		3✔
217	// Calculate the inbound fee charged for the amount that passes over the	3✔
218	// channel.	3✔
219	inboundFee := edge.inboundFees.CalcFee(amt)	3✔
220		3✔
221	// Take into account that the total node fee cannot be negative.	3✔
222	if inboundFee < -int64(nextOutFee) {	3✔
223	inboundFee = -int64(nextOutFee)	×
224	}	×
225
226	return inboundFee	3✔
227	}
228
229	// getEdgeLocal returns the optimal unified edge to use for this local
230	// connection given a specific amount to send.
231	func (u *edgeUnifier) getEdgeLocal(netAmtReceived lnwire.MilliSatoshi,
232	bandwidthHints bandwidthHints,
233	nextOutFee lnwire.MilliSatoshi) *unifiedEdge {	3✔
234		3✔
235	var (	3✔
236	bestEdge *unifiedEdge	3✔
237	maxBandwidth lnwire.MilliSatoshi	3✔
238	)	3✔
239		3✔
240	for _, edge := range u.edges {	6✔
241	// Calculate the inbound fee charged at the receiving node.	3✔
242	inboundFee := calcCappedInboundFee(	3✔
243	edge, netAmtReceived, nextOutFee,	3✔
244	)	3✔
245		3✔
246	// Add inbound fee to get to the amount that is sent over the	3✔
247	// local channel.	3✔
248	amt := netAmtReceived + lnwire.MilliSatoshi(inboundFee)	3✔
249		3✔
250	// Check valid amount range for the channel.	3✔
251	if !edge.amtInRange(amt) {	3✔
252	log.Debugf("Amount %v not in range for edge %v",	×
253	netAmtReceived, edge.policy.ChannelID)	×
254		×
255	continue	×
256	}
257
258	// For local channels, there is no fee to pay or an extra time
259	// lock. We only consider the currently available bandwidth for
260	// channel selection. The disabled flag is ignored for local
261	// channels.
262
263	// Retrieve bandwidth for this local channel. If not
264	// available, assume this channel has enough bandwidth.
265	//
266	// TODO(joostjager): Possibly change to skipping this
267	// channel. The bandwidth hint is expected to be
268	// available.
269	bandwidth, ok := bandwidthHints.availableChanBandwidth(	3✔
270	edge.policy.ChannelID, amt,	3✔
271	)	3✔
272	if !ok {	3✔
273	log.Debugf("Cannot get bandwidth for edge %v, use max "+	×
274	"instead", edge.policy.ChannelID)	×
275	bandwidth = lnwire.MaxMilliSatoshi	×
276	}	×
277
278	// TODO(yy): if the above `!ok` is chosen, we'd have
279	// `bandwidth` to be the max value, which will end up having
280	// the `maxBandwidth` to be have the largest value and this
281	// edge will be the chosen one. This is wrong in two ways,
282	// 1. we need to understand why `availableChanBandwidth` cannot
283	// find bandwidth for this edge as something is wrong with this
284	// channel, and,
285	// 2. this edge is likely NOT the local channel with the
286	// highest available bandwidth.
287	//
288	// Skip channels that can't carry the payment.
289	if amt > bandwidth {	6✔
290	log.Debugf("Skipped edge %v: not enough bandwidth, "+	3✔
291	"bandwidth=%v, amt=%v", edge.policy.ChannelID,	3✔
292	bandwidth, amt)	3✔
293		3✔
294	continue	3✔
295	}
296
297	// We pick the local channel with the highest available
298	// bandwidth, to maximize the success probability. It can be
299	// that the channel state changes between querying the bandwidth
300	// hints and sending out the htlc.
301	if bandwidth < maxBandwidth {	3✔
302	log.Debugf("Skipped edge %v: not max bandwidth, "+	×
303	"bandwidth=%v, maxBandwidth=%v",	×
304	edge.policy.ChannelID, bandwidth, maxBandwidth)	×
305		×
306	continue	×
307	}
308	maxBandwidth = bandwidth	3✔
309		3✔
310	// Update best edge.	3✔
311	bestEdge = newUnifiedEdge(	3✔
312	edge.policy, edge.capacity, edge.inboundFees,	3✔
313	edge.hopPayloadSizeFn, edge.blindedPayment,	3✔
314	)	3✔
315	}
316
317	return bestEdge	3✔
318	}
319
320	// getEdgeNetwork returns the optimal unified edge to use for this connection
321	// given a specific amount to send. The goal is to return a unified edge with a
322	// policy that maximizes the probability of a successful forward in a non-strict
323	// forwarding context.
324	func (u *edgeUnifier) getEdgeNetwork(netAmtReceived lnwire.MilliSatoshi,
325	nextOutFee lnwire.MilliSatoshi) *unifiedEdge {	3✔
326		3✔
327	var (	3✔
328	bestPolicy *unifiedEdge	3✔
329	maxFee int64 = math.MinInt64	3✔
330	maxTimelock uint16	3✔
331	maxCapMsat lnwire.MilliSatoshi	3✔
332	hopPayloadSizeFn PayloadSizeFunc	3✔
333	)	3✔
334		3✔
335	for _, edge := range u.edges {	6✔
336	// Calculate the inbound fee charged at the receiving node.	3✔
337	inboundFee := calcCappedInboundFee(	3✔
338	edge, netAmtReceived, nextOutFee,	3✔
339	)	3✔
340		3✔
341	// Add inbound fee to get to the amount that is sent over the	3✔
342	// channel.	3✔
343	amt := netAmtReceived + lnwire.MilliSatoshi(inboundFee)	3✔
344		3✔
345	// Check valid amount range for the channel.	3✔
346	if !edge.amtInRange(amt) {	6✔
347	log.Debugf("Amount %v not in range for edge %v",	3✔
348	amt, edge.policy.ChannelID)	3✔
349	continue	3✔
350	}
351
352	// For network channels, skip the disabled ones.
353	edgeFlags := edge.policy.ChannelFlags	3✔
354	isDisabled := edgeFlags&lnwire.ChanUpdateDisabled != 0	3✔
355	if isDisabled {	3✔
356	log.Debugf("Skipped edge %v due to it being disabled",	×
357	edge.policy.ChannelID)	×
358	continue	×
359	}
360
361	// Track the maximal capacity for usable channels. If we don't
362	// know the capacity, we fall back to MaxHTLC.
363	capMsat := lnwire.NewMSatFromSatoshis(edge.capacity)	3✔
364	if capMsat == 0 && edge.policy.MessageFlags.HasMaxHtlc() {	3✔
365	log.Tracef("No capacity available for channel %v, "+	×
366	"using MaxHtlcMsat (%v) as a fallback.",	×
367	edge.policy.ChannelID, edge.policy.MaxHTLC)	×
368		×
369	capMsat = edge.policy.MaxHTLC	×
370	}	×
371	maxCapMsat = lntypes.Max(capMsat, maxCapMsat)	3✔
372		3✔
373	// Track the maximum time lock of all channels that are	3✔
374	// candidate for non-strict forwarding at the routing node.	3✔
375	maxTimelock = lntypes.Max(	3✔
376	maxTimelock, edge.policy.TimeLockDelta,	3✔
377	)	3✔
378		3✔
379	outboundFee := int64(edge.policy.ComputeFee(amt))	3✔
380	fee := outboundFee + inboundFee	3✔
381		3✔
382	// Use the policy that results in the highest fee for this	3✔
383	// specific amount.	3✔
384	if fee < maxFee {	3✔
385	log.Debugf("Skipped edge %v due to it produces less "+	×
386	"fee: fee=%v, maxFee=%v",	×
387	edge.policy.ChannelID, fee, maxFee)	×
388		×
389	continue	×
390	}
391	maxFee = fee	3✔
392		3✔
393	bestPolicy = newUnifiedEdge(	3✔
394	edge.policy, 0, edge.inboundFees, nil,	3✔
395	edge.blindedPayment,	3✔
396	)	3✔
397		3✔
398	// The payload size function for edges to a connected peer is	3✔
399	// always the same hence there is not need to find the maximum.	3✔
400	// This also counts for blinded edges where we only have one	3✔
401	// edge to a blinded peer.	3✔
402	hopPayloadSizeFn = edge.hopPayloadSizeFn	3✔
403	}
404
405	// Return early if no channel matches.
406	if bestPolicy == nil {	6✔
407	return nil	3✔
408	}	3✔
409
410	// We have already picked the highest fee that could be required for
411	// non-strict forwarding. To also cover the case where a lower fee
412	// channel requires a longer time lock, we modify the policy by setting
413	// the maximum encountered time lock. Note that this results in a
414	// synthetic policy that is not actually present on the routing node.
415	//
416	// The reason we do this, is that we try to maximize the chance that we
417	// get forwarded. Because we penalize pair-wise, there won't be a second
418	// chance for this node pair. But this is all only needed for nodes that
419	// have distinct policies for channels to the same peer.
420	policyCopy := *bestPolicy.policy	3✔
421	policyCopy.TimeLockDelta = maxTimelock	3✔
422	modifiedEdge := newUnifiedEdge(	3✔
423	&policyCopy, maxCapMsat.ToSatoshis(), bestPolicy.inboundFees,	3✔
424	hopPayloadSizeFn, bestPolicy.blindedPayment,	3✔
425	)	3✔
426		3✔
427	return modifiedEdge	3✔
428	}
429
430	// minAmt returns the minimum amount that can be forwarded on this connection.
431	func (u *edgeUnifier) minAmt() lnwire.MilliSatoshi {	×
432	min := lnwire.MaxMilliSatoshi	×
433	for _, edge := range u.edges {	×
434	min = lntypes.Min(min, edge.policy.MinHTLC)	×
435	}	×
436
437	return min	×
438	}

lightningnetwork / lnd / 9915780197

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