routing/route/route: add optional MPP field to Hop

This commit also modifies the Router serialization to persist the MPP
struct when present, and properly restore it when loading from disk.
This commit is contained in:
Conner Fromknecht 2019-11-04 14:11:28 -08:00
parent b1b7ff8006
commit 6d971e5113
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GPG Key ID: E7D737B67FA592C7
5 changed files with 116 additions and 6 deletions

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@ -14,6 +14,7 @@ import (
"github.com/coreos/bbolt"
"github.com/lightningnetwork/lnd/lntypes"
"github.com/lightningnetwork/lnd/lnwire"
"github.com/lightningnetwork/lnd/record"
"github.com/lightningnetwork/lnd/routing/route"
"github.com/lightningnetwork/lnd/tlv"
)
@ -508,7 +509,9 @@ func deserializePaymentAttemptInfo(r io.Reader) (*PaymentAttemptInfo, error) {
func serializeHop(w io.Writer, h *route.Hop) error {
if err := WriteElements(w,
h.PubKeyBytes[:], h.ChannelID, h.OutgoingTimeLock,
h.PubKeyBytes[:],
h.ChannelID,
h.OutgoingTimeLock,
h.AmtToForward,
); err != nil {
return err
@ -525,10 +528,23 @@ func serializeHop(w io.Writer, h *route.Hop) error {
return WriteElements(w, uint32(0))
}
// Gather all non-primitive TLV records so that they can be serialized
// as a single blob.
//
// TODO(conner): add migration to unify all fields in a single TLV
// blobs. The split approach will cause headaches down the road as more
// fields are added, which we can avoid by having a single TLV stream
// for all payload fields.
var records []tlv.Record
if h.MPP != nil {
records = append(records, h.MPP.Record())
}
records = append(records, h.TLVRecords...)
// Otherwise, we'll transform our slice of records into a map of the
// raw bytes, then serialize them in-line with a length (number of
// elements) prefix.
mapRecords, err := tlv.RecordsToMap(h.TLVRecords)
mapRecords, err := tlv.RecordsToMap(records)
if err != nil {
return err
}
@ -604,6 +620,29 @@ func deserializeHop(r io.Reader) (*route.Hop, error) {
tlvMap[tlvType] = rawRecordBytes
}
// If the MPP type is present, remove it from the generic TLV map and
// parse it back into a proper MPP struct.
//
// TODO(conner): add migration to unify all fields in a single TLV
// blobs. The split approach will cause headaches down the road as more
// fields are added, which we can avoid by having a single TLV stream
// for all payload fields.
mppType := uint64(record.MPPOnionType)
if mppBytes, ok := tlvMap[mppType]; ok {
delete(tlvMap, mppType)
var (
mpp = &record.MPP{}
mppRec = mpp.Record()
r = bytes.NewReader(mppBytes)
)
err := mppRec.Decode(r, uint64(len(mppBytes)))
if err != nil {
return nil, err
}
h.MPP = mpp
}
tlvRecords, err := tlv.MapToRecords(tlvMap)
if err != nil {
return nil, err

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@ -12,6 +12,7 @@ import (
"github.com/btcsuite/btcd/btcec"
"github.com/davecgh/go-spew/spew"
"github.com/lightningnetwork/lnd/lntypes"
"github.com/lightningnetwork/lnd/record"
"github.com/lightningnetwork/lnd/routing/route"
"github.com/lightningnetwork/lnd/tlv"
)
@ -31,6 +32,7 @@ var (
tlv.MakeStaticRecord(1, nil, 3, tlvEncoder, nil),
tlv.MakeStaticRecord(2, nil, 3, tlvEncoder, nil),
},
MPP: record.NewMPP(32, [32]byte{0x42}),
}
testHop2 = &route.Hop{
@ -46,8 +48,8 @@ var (
TotalAmount: 1234567,
SourcePubKey: route.NewVertex(pub),
Hops: []*route.Hop{
testHop1,
testHop2,
testHop1,
},
}
)

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@ -4,6 +4,7 @@ import (
"bytes"
"encoding/binary"
"encoding/hex"
"errors"
"fmt"
"io"
"strconv"
@ -19,9 +20,17 @@ import (
// VertexSize is the size of the array to store a vertex.
const VertexSize = 33
// ErrNoRouteHopsProvided is returned when a caller attempts to construct a new
// sphinx packet, but provides an empty set of hops for each route.
var ErrNoRouteHopsProvided = fmt.Errorf("empty route hops provided")
var (
// ErrNoRouteHopsProvided is returned when a caller attempts to
// construct a new sphinx packet, but provides an empty set of hops for
// each route.
ErrNoRouteHopsProvided = fmt.Errorf("empty route hops provided")
// ErrIntermediateMPPHop is returned when a hop tries to deliver an MPP
// record to an intermediate hop, only final hops can receive MPP
// records.
ErrIntermediateMPPHop = errors.New("cannot send MPP to intermediate")
)
// Vertex is a simple alias for the serialization of a compressed Bitcoin
// public key.
@ -94,6 +103,10 @@ type Hop struct {
// carries as a fee will be subtracted by the hop.
AmtToForward lnwire.MilliSatoshi
// MPP encapsulates the data required for option_mpp. This field should
// only be set for the final hop.
MPP *record.MPP
// TLVRecords if non-nil are a set of additional TLV records that
// should be included in the forwarding instructions for this node.
TLVRecords []tlv.Record
@ -140,6 +153,17 @@ func (h *Hop) PackHopPayload(w io.Writer, nextChanID uint64) error {
)
}
// If an MPP record is destined for this hop, ensure that we only ever
// attach it to the final hop. Otherwise the route was constructed
// incorrectly.
if h.MPP != nil {
if nextChanID == 0 {
records = append(records, h.MPP.Record())
} else {
return ErrIntermediateMPPHop
}
}
// Append any custom types destined for this hop.
records = append(records, h.TLVRecords...)

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@ -1,9 +1,11 @@
package route
import (
"bytes"
"testing"
"github.com/lightningnetwork/lnd/lnwire"
"github.com/lightningnetwork/lnd/record"
)
// TestRouteTotalFees checks that a route reports the expected total fee.
@ -56,3 +58,38 @@ func TestRouteTotalFees(t *testing.T) {
}
}
var (
testAmt = lnwire.MilliSatoshi(1000)
testAddr = [32]byte{0x01, 0x02}
)
// TestMPPHop asserts that a Hop will encode a non-nil to final nodes, and fail
// when trying to send to intermediaries.
func TestMPPHop(t *testing.T) {
t.Parallel()
hop := Hop{
ChannelID: 1,
OutgoingTimeLock: 44,
AmtToForward: testAmt,
LegacyPayload: false,
MPP: record.NewMPP(testAmt, testAddr),
}
// Encoding an MPP record to an intermediate hop should result in a
// failure.
var b bytes.Buffer
err := hop.PackHopPayload(&b, 2)
if err != ErrIntermediateMPPHop {
t.Fatalf("expected err: %v, got: %v",
ErrIntermediateMPPHop, err)
}
// Encoding an MPP record to a final hop should be successful.
b.Reset()
err = hop.PackHopPayload(&b, 0)
if err != nil {
t.Fatalf("expected err: %v, got: %v", nil, err)
}
}

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@ -85,6 +85,14 @@ func (f *Record) Encode(w io.Writer) error {
return f.encoder(w, f.value, &b)
}
// Decode read in the TLV record from the passed reader. This is useful when a
// caller wants decode a *single* TLV record, outside the context of the Stream
// struct.
func (f *Record) Decode(r io.Reader, l uint64) error {
var b [8]byte
return f.decoder(r, f.value, &b, l)
}
// MakePrimitiveRecord creates a record for common types.
func MakePrimitiveRecord(typ Type, val interface{}) Record {
var (