lnd/lnrpc/routerrpc/router_backend.go
Conner Fromknecht 8cb17d5c1f
lnrpc/routerrpc/router_backend: populate and unmarshal mpp fields
This commit parses mpp_total_amt_msat and mpp_payment_addr from the
SendToRoute rpc and populates an MPP record on the internal hop
reprsentation. When the router goes to encode the onion packet, these
fields will be serialized for the destination. We also populate the mpp
fields when marshalling routes in rpc responses.
2019-11-04 15:11:23 -08:00

783 lines
22 KiB
Go

package routerrpc
import (
"context"
"encoding/hex"
"errors"
"fmt"
math "math"
"time"
"github.com/btcsuite/btcd/btcec"
"github.com/btcsuite/btcd/chaincfg"
"github.com/btcsuite/btcutil"
"github.com/lightningnetwork/lnd/lnrpc"
"github.com/lightningnetwork/lnd/lntypes"
"github.com/lightningnetwork/lnd/lnwire"
"github.com/lightningnetwork/lnd/record"
"github.com/lightningnetwork/lnd/routing"
"github.com/lightningnetwork/lnd/routing/route"
"github.com/lightningnetwork/lnd/tlv"
"github.com/lightningnetwork/lnd/zpay32"
)
// RouterBackend contains the backend implementation of the router rpc sub
// server calls.
type RouterBackend struct {
// MaxPaymentMSat is the largest payment permitted by the backend.
MaxPaymentMSat lnwire.MilliSatoshi
// SelfNode is the vertex of the node sending the payment.
SelfNode route.Vertex
// 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)
// FetchChannelEndpoints returns the pubkeys of both endpoints of the
// given channel id.
FetchChannelEndpoints func(chanID uint64) (route.Vertex,
route.Vertex, error)
// FindRoutes is a closure that abstracts away how we locate/query for
// routes.
FindRoute func(source, target route.Vertex,
amt lnwire.MilliSatoshi, restrictions *routing.RestrictParams,
destTlvRecords []tlv.Record,
finalExpiry ...uint16) (*route.Route, error)
MissionControl MissionControl
// ActiveNetParams are the network parameters of the primary network
// that the route is operating on. This is necessary so we can ensure
// that we receive payment requests that send to destinations on our
// network.
ActiveNetParams *chaincfg.Params
// Tower is the ControlTower instance that is used to track pending
// payments.
Tower routing.ControlTower
// MaxTotalTimelock is the maximum total time lock a route is allowed to
// have.
MaxTotalTimelock uint32
}
// MissionControl defines the mission control dependencies of routerrpc.
type MissionControl interface {
// GetProbability is expected to return the success probability of a
// payment from fromNode to toNode.
GetProbability(fromNode, toNode route.Vertex,
amt lnwire.MilliSatoshi) float64
// ResetHistory resets the history of MissionControl returning it to a
// state as if no payment attempts have been made.
ResetHistory() error
// GetHistorySnapshot takes a snapshot from the current mission control
// state and actual probability estimates.
GetHistorySnapshot() *routing.MissionControlSnapshot
// GetPairHistorySnapshot returns the stored history for a given node
// pair.
GetPairHistorySnapshot(fromNode,
toNode route.Vertex) routing.TimedPairResult
}
// 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.
//
// 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
}
return route.NewVertexFromBytes(pubKeyBytes)
}
// 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 {
ignoreVertex, err := route.NewVertexFromBytes(ignorePubKey)
if err != nil {
return nil, err
}
ignoredNodes[ignoreVertex] = struct{}{}
}
ignoredPairs := make(map[routing.DirectedNodePair]struct{})
// Convert deprecated ignoredEdges to pairs.
for _, ignoredEdge := range in.IgnoredEdges {
pair, err := r.rpcEdgeToPair(ignoredEdge)
if err != nil {
log.Warnf("Ignore channel %v skipped: %v",
ignoredEdge.ChannelId, err)
continue
}
ignoredPairs[pair] = struct{}{}
}
// Add ignored pairs to set.
for _, ignorePair := range in.IgnoredPairs {
from, err := route.NewVertexFromBytes(ignorePair.From)
if err != nil {
return nil, err
}
to, err := route.NewVertexFromBytes(ignorePair.To)
if err != nil {
return nil, err
}
pair := routing.NewDirectedNodePair(from, to)
ignoredPairs[pair] = struct{}{}
}
// Since QueryRoutes allows having a different source other than
// ourselves, we'll only apply our max time lock if we are the source.
maxTotalTimelock := r.MaxTotalTimelock
if sourcePubKey != r.SelfNode {
maxTotalTimelock = math.MaxUint32
}
cltvLimit, err := ValidateCLTVLimit(in.CltvLimit, maxTotalTimelock)
if err != nil {
return nil, err
}
// We need to subtract the final delta before passing it into path
// finding. The optimal path is independent of the final cltv delta and
// the path finding algorithm is unaware of this value.
finalCLTVDelta := uint16(zpay32.DefaultFinalCLTVDelta)
if in.FinalCltvDelta != 0 {
finalCLTVDelta = uint16(in.FinalCltvDelta)
}
cltvLimit -= uint32(finalCLTVDelta)
var destTLV map[uint64][]byte
restrictions := &routing.RestrictParams{
FeeLimit: feeLimit,
ProbabilitySource: func(fromNode, toNode route.Vertex,
amt lnwire.MilliSatoshi) float64 {
if _, ok := ignoredNodes[fromNode]; ok {
return 0
}
pair := routing.DirectedNodePair{
From: fromNode,
To: toNode,
}
if _, ok := ignoredPairs[pair]; ok {
return 0
}
if !in.UseMissionControl {
return 1
}
return r.MissionControl.GetProbability(
fromNode, toNode, amt,
)
},
DestPayloadTLV: len(destTLV) != 0,
CltvLimit: cltvLimit,
}
// If we have any TLV records destined for the final hop, then we'll
// attempt to decode them now into a form that the router can more
// easily manipulate.
destTlvRecords, err := tlv.MapToRecords(destTLV)
if err != nil {
return nil, err
}
// 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.
route, err := r.FindRoute(
sourcePubKey, targetPubKey, amtMSat, restrictions,
destTlvRecords, finalCLTVDelta,
)
if err != nil {
return nil, err
}
// For each valid route, we'll convert the result into the format
// required by the RPC system.
rpcRoute, err := r.MarshallRoute(route)
if err != nil {
return nil, err
}
// Calculate route success probability. Do not rely on a probability
// that could have been returned from path finding, because mission
// control may have been disabled in the provided ProbabilitySource.
successProb := r.getSuccessProbability(route)
routeResp := &lnrpc.QueryRoutesResponse{
Routes: []*lnrpc.Route{rpcRoute},
SuccessProb: successProb,
}
return routeResp, nil
}
// getSuccessProbability returns the success probability for the given route
// based on the current state of mission control.
func (r *RouterBackend) getSuccessProbability(rt *route.Route) float64 {
fromNode := rt.SourcePubKey
amtToFwd := rt.TotalAmount
successProb := 1.0
for _, hop := range rt.Hops {
toNode := hop.PubKeyBytes
probability := r.MissionControl.GetProbability(
fromNode, toNode, amtToFwd,
)
successProb *= probability
amtToFwd = hop.AmtToForward
fromNode = toNode
}
return successProb
}
// rpcEdgeToPair looks up the provided channel and returns the channel endpoints
// as a directed pair.
func (r *RouterBackend) rpcEdgeToPair(e *lnrpc.EdgeLocator) (
routing.DirectedNodePair, error) {
a, b, err := r.FetchChannelEndpoints(e.ChannelId)
if err != nil {
return routing.DirectedNodePair{}, err
}
var pair routing.DirectedNodePair
if e.DirectionReverse {
pair.From, pair.To = b, a
} else {
pair.From, pair.To = a, b
}
return pair, 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, error) {
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()
}
// Extract the MPP fields if present on this hop.
var mpp *lnrpc.MPPRecord
if hop.MPP != nil {
addr := hop.MPP.PaymentAddr()
mpp = &lnrpc.MPPRecord{
PaymentAddr: addr[:],
TotalAmtMsat: int64(hop.MPP.TotalMsat()),
}
}
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(
hop.PubKeyBytes[:],
),
TlvPayload: !hop.LegacyPayload,
MppRecord: mpp,
}
incomingAmt = hop.AmtToForward
}
return resp, nil
}
// UnmarshallHopByChannelLookup unmarshalls an rpc hop for which the pub key is
// not known. This function will query the channel graph with channel id to
// retrieve both endpoints and determine the hop pubkey using the previous hop
// pubkey. If the channel is unknown, an error is returned.
func (r *RouterBackend) UnmarshallHopByChannelLookup(hop *lnrpc.Hop,
prevPubKeyBytes [33]byte) (*route.Hop, error) {
// Discard edge policies, because they may be nil.
node1, node2, err := r.FetchChannelEndpoints(hop.ChanId)
if err != nil {
return nil, err
}
var pubKeyBytes [33]byte
switch {
case prevPubKeyBytes == node1:
pubKeyBytes = node2
case prevPubKeyBytes == node2:
pubKeyBytes = node1
default:
return nil, fmt.Errorf("channel edge does not match expected node")
}
var tlvRecords []tlv.Record
mpp, err := UnmarshalMPP(hop.MppRecord)
if err != nil {
return nil, err
}
return &route.Hop{
OutgoingTimeLock: hop.Expiry,
AmtToForward: lnwire.MilliSatoshi(hop.AmtToForwardMsat),
PubKeyBytes: pubKeyBytes,
ChannelID: hop.ChanId,
TLVRecords: tlvRecords,
LegacyPayload: !hop.TlvPayload,
MPP: mpp,
}, nil
}
// UnmarshallKnownPubkeyHop unmarshalls an rpc hop that contains the hop pubkey.
// The channel graph doesn't need to be queried because all information required
// for sending the payment is present.
func UnmarshallKnownPubkeyHop(hop *lnrpc.Hop) (*route.Hop, error) {
pubKey, err := hex.DecodeString(hop.PubKey)
if err != nil {
return nil, fmt.Errorf("cannot decode pubkey %s", hop.PubKey)
}
var pubKeyBytes [33]byte
copy(pubKeyBytes[:], pubKey)
var tlvRecords []tlv.Record
mpp, err := UnmarshalMPP(hop.MppRecord)
if err != nil {
return nil, err
}
return &route.Hop{
OutgoingTimeLock: hop.Expiry,
AmtToForward: lnwire.MilliSatoshi(hop.AmtToForwardMsat),
PubKeyBytes: pubKeyBytes,
ChannelID: hop.ChanId,
TLVRecords: tlvRecords,
LegacyPayload: !hop.TlvPayload,
MPP: mpp,
}, nil
}
// UnmarshallHop unmarshalls an rpc hop that may or may not contain a node
// pubkey.
func (r *RouterBackend) UnmarshallHop(hop *lnrpc.Hop,
prevNodePubKey [33]byte) (*route.Hop, error) {
if hop.PubKey == "" {
// If no pub key is given of the hop, the local channel
// graph needs to be queried to complete the information
// necessary for routing.
return r.UnmarshallHopByChannelLookup(hop, prevNodePubKey)
}
return UnmarshallKnownPubkeyHop(hop)
}
// UnmarshallRoute unmarshalls an rpc route. For hops that don't specify a
// pubkey, the channel graph is queried.
func (r *RouterBackend) UnmarshallRoute(rpcroute *lnrpc.Route) (
*route.Route, error) {
prevNodePubKey := r.SelfNode
hops := make([]*route.Hop, len(rpcroute.Hops))
for i, hop := range rpcroute.Hops {
routeHop, err := r.UnmarshallHop(hop, prevNodePubKey)
if err != nil {
return nil, err
}
hops[i] = routeHop
prevNodePubKey = routeHop.PubKeyBytes
}
route, err := route.NewRouteFromHops(
lnwire.MilliSatoshi(rpcroute.TotalAmtMsat),
rpcroute.TotalTimeLock,
r.SelfNode,
hops,
)
if err != nil {
return nil, err
}
return route, nil
}
// extractIntentFromSendRequest attempts to parse the SendRequest details
// required to dispatch a client from the information presented by an RPC
// client.
func (r *RouterBackend) extractIntentFromSendRequest(
rpcPayReq *SendPaymentRequest) (*routing.LightningPayment, error) {
payIntent := &routing.LightningPayment{}
// Pass along an outgoing channel restriction if specified.
if rpcPayReq.OutgoingChanId != 0 {
payIntent.OutgoingChannelID = &rpcPayReq.OutgoingChanId
}
// Take the CLTV limit from the request if set, otherwise use the max.
cltvLimit, err := ValidateCLTVLimit(
uint32(rpcPayReq.CltvLimit), r.MaxTotalTimelock,
)
if err != nil {
return nil, err
}
payIntent.CltvLimit = cltvLimit
// Take fee limit from request.
payIntent.FeeLimit = lnwire.NewMSatFromSatoshis(
btcutil.Amount(rpcPayReq.FeeLimitSat),
)
// Set payment attempt timeout.
if rpcPayReq.TimeoutSeconds == 0 {
return nil, errors.New("timeout_seconds must be specified")
}
var destTLV map[uint64][]byte
if len(destTLV) != 0 {
var err error
payIntent.FinalDestRecords, err = tlv.MapToRecords(destTLV)
if err != nil {
return nil, err
}
}
payIntent.PayAttemptTimeout = time.Second *
time.Duration(rpcPayReq.TimeoutSeconds)
// Route hints.
routeHints, err := unmarshallRouteHints(
rpcPayReq.RouteHints,
)
if err != nil {
return nil, err
}
payIntent.RouteHints = routeHints
// If the payment request field isn't blank, then the details of the
// invoice are encoded entirely within the encoded payReq. So we'll
// attempt to decode it, populating the payment accordingly.
if rpcPayReq.PaymentRequest != "" {
switch {
case len(rpcPayReq.Dest) > 0:
return nil, errors.New("dest and payment_request " +
"cannot appear together")
case len(rpcPayReq.PaymentHash) > 0:
return nil, errors.New("dest and payment_hash " +
"cannot appear together")
case rpcPayReq.FinalCltvDelta != 0:
return nil, errors.New("dest and final_cltv_delta " +
"cannot appear together")
}
payReq, err := zpay32.Decode(
rpcPayReq.PaymentRequest, r.ActiveNetParams,
)
if err != nil {
return nil, err
}
// Next, we'll ensure that this payreq hasn't already expired.
err = ValidatePayReqExpiry(payReq)
if err != nil {
return nil, err
}
// If the amount was not included in the invoice, then we let
// the payee specify the amount of satoshis they wish to send.
// We override the amount to pay with the amount provided from
// the payment request.
if payReq.MilliSat == nil {
if rpcPayReq.Amt == 0 {
return nil, errors.New("amount must be " +
"specified when paying a zero amount " +
"invoice")
}
payIntent.Amount = lnwire.NewMSatFromSatoshis(
btcutil.Amount(rpcPayReq.Amt),
)
} else {
if rpcPayReq.Amt != 0 {
return nil, errors.New("amount must not be " +
"specified when paying a non-zero " +
" amount invoice")
}
payIntent.Amount = *payReq.MilliSat
}
copy(payIntent.PaymentHash[:], payReq.PaymentHash[:])
destKey := payReq.Destination.SerializeCompressed()
copy(payIntent.Target[:], destKey)
payIntent.FinalCLTVDelta = uint16(payReq.MinFinalCLTVExpiry())
payIntent.RouteHints = append(
payIntent.RouteHints, payReq.RouteHints...,
)
} else {
// Otherwise, If the payment request field was not specified
// (and a custom route wasn't specified), construct the payment
// from the other fields.
// Payment destination.
target, err := route.NewVertexFromBytes(rpcPayReq.Dest)
if err != nil {
return nil, err
}
payIntent.Target = target
// Final payment CLTV delta.
if rpcPayReq.FinalCltvDelta != 0 {
payIntent.FinalCLTVDelta =
uint16(rpcPayReq.FinalCltvDelta)
} else {
payIntent.FinalCLTVDelta = zpay32.DefaultFinalCLTVDelta
}
// Amount.
if rpcPayReq.Amt == 0 {
return nil, errors.New("amount must be specified")
}
payIntent.Amount = lnwire.NewMSatFromSatoshis(
btcutil.Amount(rpcPayReq.Amt),
)
// Payment hash.
copy(payIntent.PaymentHash[:], rpcPayReq.PaymentHash)
}
// 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.
if payIntent.Amount > r.MaxPaymentMSat {
// In this case, we'll send an error to the caller, but
// continue our loop for the next payment.
return payIntent, fmt.Errorf("payment of %v is too large, "+
"max payment allowed is %v", payIntent.Amount,
r.MaxPaymentMSat)
}
return payIntent, nil
}
// unmarshallRouteHints unmarshalls a list of route hints.
func unmarshallRouteHints(rpcRouteHints []*lnrpc.RouteHint) (
[][]zpay32.HopHint, error) {
routeHints := make([][]zpay32.HopHint, 0, len(rpcRouteHints))
for _, rpcRouteHint := range rpcRouteHints {
routeHint := make(
[]zpay32.HopHint, 0, len(rpcRouteHint.HopHints),
)
for _, rpcHint := range rpcRouteHint.HopHints {
hint, err := unmarshallHopHint(rpcHint)
if err != nil {
return nil, err
}
routeHint = append(routeHint, hint)
}
routeHints = append(routeHints, routeHint)
}
return routeHints, nil
}
// unmarshallHopHint unmarshalls a single hop hint.
func unmarshallHopHint(rpcHint *lnrpc.HopHint) (zpay32.HopHint, error) {
pubBytes, err := hex.DecodeString(rpcHint.NodeId)
if err != nil {
return zpay32.HopHint{}, err
}
pubkey, err := btcec.ParsePubKey(pubBytes, btcec.S256())
if err != nil {
return zpay32.HopHint{}, err
}
return zpay32.HopHint{
NodeID: pubkey,
ChannelID: rpcHint.ChanId,
FeeBaseMSat: rpcHint.FeeBaseMsat,
FeeProportionalMillionths: rpcHint.FeeProportionalMillionths,
CLTVExpiryDelta: uint16(rpcHint.CltvExpiryDelta),
}, nil
}
// ValidatePayReqExpiry checks if the passed payment request has expired. In
// the case it has expired, an error will be returned.
func ValidatePayReqExpiry(payReq *zpay32.Invoice) error {
expiry := payReq.Expiry()
validUntil := payReq.Timestamp.Add(expiry)
if time.Now().After(validUntil) {
return fmt.Errorf("invoice expired. Valid until %v", validUntil)
}
return nil
}
// ValidateCLTVLimit returns a valid CLTV limit given a value and a maximum. If
// the value exceeds the maximum, then an error is returned. If the value is 0,
// then the maximum is used.
func ValidateCLTVLimit(val, max uint32) (uint32, error) {
switch {
case val == 0:
return max, nil
case val > max:
return 0, fmt.Errorf("total time lock of %v exceeds max "+
"allowed %v", val, max)
default:
return val, nil
}
}
// UnmarshalMPP accepts the mpp_total_amt_msat and mpp_payment_addr fields from
// an RPC request and converts into an record.MPP object. An error is returned
// if the payment address is not 0 or 32 bytes. If the total amount and payment
// address are zero-value, the return value will be nil signaling there is no
// MPP record to attach to this hop. Otherwise, a non-nil reocrd will be
// contained combining the provided values.
func UnmarshalMPP(reqMPP *lnrpc.MPPRecord) (*record.MPP, error) {
// If no MPP record was submitted, assume the user wants to send a
// regular payment.
if reqMPP == nil {
return nil, nil
}
reqTotal := reqMPP.TotalAmtMsat
reqAddr := reqMPP.PaymentAddr
switch {
// No MPP fields were provided.
case reqTotal == 0 && len(reqAddr) == 0:
return nil, fmt.Errorf("missing total_msat and payment_addr")
// Total is present, but payment address is missing.
case reqTotal > 0 && len(reqAddr) == 0:
return nil, fmt.Errorf("missing payment_addr")
// Payment address is present, but total is missing.
case reqTotal == 0 && len(reqAddr) > 0:
return nil, fmt.Errorf("missing total_msat")
}
addr, err := lntypes.MakeHash(reqAddr)
if err != nil {
return nil, fmt.Errorf("unable to parse "+
"payment_addr: %v", err)
}
total := lnwire.MilliSatoshi(reqTotal)
return record.NewMPP(total, addr), nil
}