lnd.xprv/htlcswitch/hop/payload.go

242 lines
6.8 KiB
Go

package hop
import (
"encoding/binary"
"fmt"
"io"
sphinx "github.com/lightningnetwork/lightning-onion"
"github.com/lightningnetwork/lnd/lnwire"
"github.com/lightningnetwork/lnd/record"
"github.com/lightningnetwork/lnd/tlv"
)
// PayloadViolation is an enum encapsulating the possible invalid payload
// violations that can occur when processing or validating a payload.
type PayloadViolation byte
const (
// OmittedViolation indicates that a type was expected to be found the
// payload but was absent.
OmittedViolation PayloadViolation = iota
// IncludedViolation indicates that a type was expected to be omitted
// from the payload but was present.
IncludedViolation
// RequiredViolation indicates that an unknown even type was found in
// the payload that we could not process.
RequiredViolation
)
// String returns a human-readable description of the violation as a verb.
func (v PayloadViolation) String() string {
switch v {
case OmittedViolation:
return "omitted"
case IncludedViolation:
return "included"
case RequiredViolation:
return "required"
default:
return "unknown violation"
}
}
// ErrInvalidPayload is an error returned when a parsed onion payload either
// included or omitted incorrect records for a particular hop type.
type ErrInvalidPayload struct {
// Type the record's type that cause the violation.
Type tlv.Type
// Violation is an enum indicating the type of violation detected in
// processing Type.
Violation PayloadViolation
// FinalHop if true, indicates that the violation is for the final hop
// in the route (identified by next hop id), otherwise the violation is
// for an intermediate hop.
FinalHop bool
}
// Error returns a human-readable description of the invalid payload error.
func (e ErrInvalidPayload) Error() string {
hopType := "intermediate"
if e.FinalHop {
hopType = "final"
}
return fmt.Sprintf("onion payload for %s hop %v record with type %d",
hopType, e.Violation, e.Type)
}
// Payload encapsulates all information delivered to a hop in an onion payload.
// A Hop can represent either a TLV or legacy payload. The primary forwarding
// instruction can be accessed via ForwardingInfo, and additional records can be
// accessed by other member functions.
type Payload struct {
// FwdInfo holds the basic parameters required for HTLC forwarding, e.g.
// amount, cltv, and next hop.
FwdInfo ForwardingInfo
// MPP holds the info provided in an option_mpp record when parsed from
// a TLV onion payload.
MPP *record.MPP
}
// NewLegacyPayload builds a Payload from the amount, cltv, and next hop
// parameters provided by leegacy onion payloads.
func NewLegacyPayload(f *sphinx.HopData) *Payload {
nextHop := binary.BigEndian.Uint64(f.NextAddress[:])
return &Payload{
FwdInfo: ForwardingInfo{
Network: BitcoinNetwork,
NextHop: lnwire.NewShortChanIDFromInt(nextHop),
AmountToForward: lnwire.MilliSatoshi(f.ForwardAmount),
OutgoingCTLV: f.OutgoingCltv,
},
}
}
// NewPayloadFromReader builds a new Hop from the passed io.Reader. The reader
// should correspond to the bytes encapsulated in a TLV onion payload.
func NewPayloadFromReader(r io.Reader) (*Payload, error) {
var (
cid uint64
amt uint64
cltv uint32
mpp = &record.MPP{}
)
tlvStream, err := tlv.NewStream(
record.NewAmtToFwdRecord(&amt),
record.NewLockTimeRecord(&cltv),
record.NewNextHopIDRecord(&cid),
mpp.Record(),
)
if err != nil {
return nil, err
}
parsedTypes, err := tlvStream.DecodeWithParsedTypes(r)
if err != nil {
// Promote any required type failures into ErrInvalidPayload.
if e, required := err.(tlv.ErrUnknownRequiredType); required {
// If the parser returned an unknown required type
// failure, we'll first check that the payload is
// properly formed according to our known set of
// constraints. If an error is discovered, this
// overrides the required type failure.
nextHop := lnwire.NewShortChanIDFromInt(cid)
err = ValidateParsedPayloadTypes(parsedTypes, nextHop)
if err != nil {
return nil, err
}
// Otherwise the known constraints were applied
// successfully, report the invalid type failure
// returned by the parser.
return nil, ErrInvalidPayload{
Type: tlv.Type(e),
Violation: RequiredViolation,
FinalHop: nextHop == Exit,
}
}
return nil, err
}
// Validate whether the sender properly included or omitted tlv records
// in accordance with BOLT 04.
nextHop := lnwire.NewShortChanIDFromInt(cid)
err = ValidateParsedPayloadTypes(parsedTypes, nextHop)
if err != nil {
return nil, err
}
// If no MPP field was parsed, set the MPP field on the resulting
// payload to nil.
if _, ok := parsedTypes[record.MPPOnionType]; !ok {
mpp = nil
}
return &Payload{
FwdInfo: ForwardingInfo{
Network: BitcoinNetwork,
NextHop: nextHop,
AmountToForward: lnwire.MilliSatoshi(amt),
OutgoingCTLV: cltv,
},
MPP: mpp,
}, nil
}
// ForwardingInfo returns the basic parameters required for HTLC forwarding,
// e.g. amount, cltv, and next hop.
func (h *Payload) ForwardingInfo() ForwardingInfo {
return h.FwdInfo
}
// ValidateParsedPayloadTypes checks the types parsed from a hop payload to
// ensure that the proper fields are either included or omitted. The finalHop
// boolean should be true if the payload was parsed for an exit hop. The
// requirements for this method are described in BOLT 04.
func ValidateParsedPayloadTypes(parsedTypes tlv.TypeSet,
nextHop lnwire.ShortChannelID) error {
isFinalHop := nextHop == Exit
_, hasAmt := parsedTypes[record.AmtOnionType]
_, hasLockTime := parsedTypes[record.LockTimeOnionType]
_, hasNextHop := parsedTypes[record.NextHopOnionType]
_, hasMPP := parsedTypes[record.MPPOnionType]
switch {
// All hops must include an amount to forward.
case !hasAmt:
return ErrInvalidPayload{
Type: record.AmtOnionType,
Violation: OmittedViolation,
FinalHop: isFinalHop,
}
// All hops must include a cltv expiry.
case !hasLockTime:
return ErrInvalidPayload{
Type: record.LockTimeOnionType,
Violation: OmittedViolation,
FinalHop: isFinalHop,
}
// The exit hop should omit the next hop id. If nextHop != Exit, the
// sender must have included a record, so we don't need to test for its
// inclusion at intermediate hops directly.
case isFinalHop && hasNextHop:
return ErrInvalidPayload{
Type: record.NextHopOnionType,
Violation: IncludedViolation,
FinalHop: true,
}
// Intermediate nodes should never receive MPP fields.
case !isFinalHop && hasMPP:
return ErrInvalidPayload{
Type: record.MPPOnionType,
Violation: IncludedViolation,
FinalHop: isFinalHop,
}
}
return nil
}
// MultiPath returns the record corresponding the option_mpp parsed from the
// onion payload.
func (h *Payload) MultiPath() *record.MPP {
return h.MPP
}