lnd.xprv/lnrpc/routerrpc/router_backend.go

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package routerrpc
import (
"encoding/hex"
"errors"
"fmt"
"github.com/btcsuite/btcutil"
"github.com/lightningnetwork/lnd/lnrpc"
"github.com/lightningnetwork/lnd/lnwire"
"github.com/lightningnetwork/lnd/routing"
"github.com/lightningnetwork/lnd/routing/route"
context "golang.org/x/net/context"
)
// RouterBackend contains the backend implementation of the router rpc sub
// server calls.
type RouterBackend struct {
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// MaxPaymentMSat is the largest payment permitted by the backend.
MaxPaymentMSat lnwire.MilliSatoshi
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// SelfNode is the vertex of the node sending the payment.
SelfNode route.Vertex
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// FetchChannelCapacity is a closure that we'll use the fetch the total
// capacity of a channel to populate in responses.
FetchChannelCapacity func(chanID uint64) (btcutil.Amount, error)
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// FindRoutes is a closure that abstracts away how we locate/query for
// routes.
FindRoutes func(source, target route.Vertex,
amt lnwire.MilliSatoshi, restrictions *routing.RestrictParams,
numPaths uint32, finalExpiry ...uint16) (
[]*route.Route, error)
}
// QueryRoutes attempts to query the daemons' Channel Router for a possible
// route to a target destination capable of carrying a specific amount of
// satoshis within the route's flow. The retuned route contains the full
// details required to craft and send an HTLC, also including the necessary
// information that should be present within the Sphinx packet encapsulated
// within the HTLC.
//
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// TODO(roasbeef): should return a slice of routes in reality * create separate
// PR to send based on well formatted route
func (r *RouterBackend) QueryRoutes(ctx context.Context,
in *lnrpc.QueryRoutesRequest) (*lnrpc.QueryRoutesResponse, error) {
parsePubKey := func(key string) (route.Vertex, error) {
pubKeyBytes, err := hex.DecodeString(key)
if err != nil {
return route.Vertex{}, err
}
if len(pubKeyBytes) != 33 {
return route.Vertex{},
errors.New("invalid key length")
}
var v route.Vertex
copy(v[:], pubKeyBytes)
return v, nil
}
// Parse the hex-encoded source and target public keys into full public
// key objects we can properly manipulate.
targetPubKey, err := parsePubKey(in.PubKey)
if err != nil {
return nil, err
}
var sourcePubKey route.Vertex
if in.SourcePubKey != "" {
var err error
sourcePubKey, err = parsePubKey(in.SourcePubKey)
if err != nil {
return nil, err
}
} else {
// If no source is specified, use self.
sourcePubKey = r.SelfNode
}
// Currently, within the bootstrap phase of the network, we limit the
// largest payment size allotted to (2^32) - 1 mSAT or 4.29 million
// satoshis.
amt := btcutil.Amount(in.Amt)
amtMSat := lnwire.NewMSatFromSatoshis(amt)
if amtMSat > r.MaxPaymentMSat {
return nil, fmt.Errorf("payment of %v is too large, max payment "+
"allowed is %v", amt, r.MaxPaymentMSat.ToSatoshis())
}
// Unmarshall restrictions from request.
feeLimit := calculateFeeLimit(in.FeeLimit, amtMSat)
ignoredNodes := make(map[route.Vertex]struct{})
for _, ignorePubKey := range in.IgnoredNodes {
if len(ignorePubKey) != 33 {
return nil, fmt.Errorf("invalid ignore node pubkey")
}
var ignoreVertex route.Vertex
copy(ignoreVertex[:], ignorePubKey)
ignoredNodes[ignoreVertex] = struct{}{}
}
ignoredEdges := make(map[routing.EdgeLocator]struct{})
for _, ignoredEdge := range in.IgnoredEdges {
locator := routing.EdgeLocator{
ChannelID: ignoredEdge.ChannelId,
}
if ignoredEdge.DirectionReverse {
locator.Direction = 1
}
ignoredEdges[locator] = struct{}{}
}
restrictions := &routing.RestrictParams{
FeeLimit: feeLimit,
IgnoredNodes: ignoredNodes,
IgnoredEdges: ignoredEdges,
}
// numRoutes will default to 10 if not specified explicitly.
numRoutesIn := uint32(in.NumRoutes)
if numRoutesIn == 0 {
numRoutesIn = 10
}
// Query the channel router for a possible path to the destination that
// can carry `in.Amt` satoshis _including_ the total fee required on
// the route.
var (
routes []*route.Route
findErr error
)
if in.FinalCltvDelta == 0 {
routes, findErr = r.FindRoutes(
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sourcePubKey, targetPubKey, amtMSat, restrictions,
numRoutesIn,
)
} else {
routes, findErr = r.FindRoutes(
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sourcePubKey, targetPubKey, amtMSat, restrictions,
numRoutesIn, uint16(in.FinalCltvDelta),
)
}
if findErr != nil {
return nil, findErr
}
// As the number of returned routes can be less than the number of
// requested routes, we'll clamp down the length of the response to the
// minimum of the two.
numRoutes := uint32(len(routes))
if numRoutesIn < numRoutes {
numRoutes = numRoutesIn
}
// For each valid route, we'll convert the result into the format
// required by the RPC system.
routeResp := &lnrpc.QueryRoutesResponse{
Routes: make([]*lnrpc.Route, 0, in.NumRoutes),
}
for i := uint32(0); i < numRoutes; i++ {
routeResp.Routes = append(
routeResp.Routes,
r.MarshallRoute(routes[i]),
)
}
return routeResp, nil
}
// calculateFeeLimit returns the fee limit in millisatoshis. If a percentage
// based fee limit has been requested, we'll factor in the ratio provided with
// the amount of the payment.
func calculateFeeLimit(feeLimit *lnrpc.FeeLimit,
amount lnwire.MilliSatoshi) lnwire.MilliSatoshi {
switch feeLimit.GetLimit().(type) {
case *lnrpc.FeeLimit_Fixed:
return lnwire.NewMSatFromSatoshis(
btcutil.Amount(feeLimit.GetFixed()),
)
case *lnrpc.FeeLimit_Percent:
return amount * lnwire.MilliSatoshi(feeLimit.GetPercent()) / 100
default:
// If a fee limit was not specified, we'll use the payment's
// amount as an upper bound in order to avoid payment attempts
// from incurring fees higher than the payment amount itself.
return amount
}
}
// MarshallRoute marshalls an internal route to an rpc route struct.
func (r *RouterBackend) MarshallRoute(route *route.Route) *lnrpc.Route {
resp := &lnrpc.Route{
TotalTimeLock: route.TotalTimeLock,
TotalFees: int64(route.TotalFees.ToSatoshis()),
TotalFeesMsat: int64(route.TotalFees),
TotalAmt: int64(route.TotalAmount.ToSatoshis()),
TotalAmtMsat: int64(route.TotalAmount),
Hops: make([]*lnrpc.Hop, len(route.Hops)),
}
incomingAmt := route.TotalAmount
for i, hop := range route.Hops {
fee := route.HopFee(i)
// Channel capacity is not a defining property of a route. For
// backwards RPC compatibility, we retrieve it here from the
// graph.
chanCapacity, err := r.FetchChannelCapacity(hop.ChannelID)
if err != nil {
// If capacity cannot be retrieved, this may be a
// not-yet-received or private channel. Then report
// amount that is sent through the channel as capacity.
chanCapacity = incomingAmt.ToSatoshis()
}
resp.Hops[i] = &lnrpc.Hop{
ChanId: hop.ChannelID,
ChanCapacity: int64(chanCapacity),
AmtToForward: int64(hop.AmtToForward.ToSatoshis()),
AmtToForwardMsat: int64(hop.AmtToForward),
Fee: int64(fee.ToSatoshis()),
FeeMsat: int64(fee),
Expiry: uint32(hop.OutgoingTimeLock),
PubKey: hex.EncodeToString(
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hop.PubKeyBytes[:],
),
}
incomingAmt = hop.AmtToForward
}
return resp
}