lnd.xprv/record/amp.go
Conner Fromknecht 82b4f11292
record/amp: use switch from 10 -> 14 for AMP TLV type
This is to not conflict with trampoline BOLT.
2021-04-07 12:08:33 -07:00

108 lines
2.8 KiB
Go

package record
import (
"fmt"
"io"
"github.com/lightningnetwork/lnd/tlv"
)
// AMPOnionType is the type used in the onion to reference the AMP fields:
// root_share, set_id, and child_index.
const AMPOnionType tlv.Type = 14
// AMP is a record that encodes the fields necessary for atomic multi-path
// payments.
type AMP struct {
rootShare [32]byte
setID [32]byte
childIndex uint32
}
// NewAMP generate a new AMP record with the given root_share, set_id, and
// child_index.
func NewAMP(rootShare, setID [32]byte, childIndex uint32) *AMP {
return &AMP{
rootShare: rootShare,
setID: setID,
childIndex: childIndex,
}
}
// RootShare returns the root share contained in the AMP record.
func (a *AMP) RootShare() [32]byte {
return a.rootShare
}
// SetID returns the set id contained in the AMP record.
func (a *AMP) SetID() [32]byte {
return a.setID
}
// ChildIndex returns the child index contained in the AMP record.
func (a *AMP) ChildIndex() uint32 {
return a.childIndex
}
// AMPEncoder writes the AMP record to the provided io.Writer.
func AMPEncoder(w io.Writer, val interface{}, buf *[8]byte) error {
if v, ok := val.(*AMP); ok {
if err := tlv.EBytes32(w, &v.rootShare, buf); err != nil {
return err
}
if err := tlv.EBytes32(w, &v.setID, buf); err != nil {
return err
}
return tlv.ETUint32T(w, v.childIndex, buf)
}
return tlv.NewTypeForEncodingErr(val, "AMP")
}
const (
// minAMPLength is the minimum length of a serialized AMP TLV record,
// which occurs when the truncated encoding of child_index takes 0
// bytes, leaving only the root_share and set_id.
minAMPLength = 64
// maxAMPLength is the maximum legnth of a serialized AMP TLV record,
// which occurs when the truncated endoing of a child_index takes 2
// bytes.
maxAMPLength = 68
)
// AMPDecoder reads the AMP record from the provided io.Reader.
func AMPDecoder(r io.Reader, val interface{}, buf *[8]byte, l uint64) error {
if v, ok := val.(*AMP); ok && minAMPLength <= l && l <= maxAMPLength {
if err := tlv.DBytes32(r, &v.rootShare, buf, 32); err != nil {
return err
}
if err := tlv.DBytes32(r, &v.setID, buf, 32); err != nil {
return err
}
return tlv.DTUint32(r, &v.childIndex, buf, l-minAMPLength)
}
return tlv.NewTypeForDecodingErr(val, "AMP", l, maxAMPLength)
}
// Record returns a tlv.Record that can be used to encode or decode this record.
func (a *AMP) Record() tlv.Record {
return tlv.MakeDynamicRecord(
AMPOnionType, a, a.PayloadSize, AMPEncoder, AMPDecoder,
)
}
// PayloadSize returns the size this record takes up in encoded form.
func (a *AMP) PayloadSize() uint64 {
return 32 + 32 + tlv.SizeTUint32(a.childIndex)
}
// String returns a human-readble description of the amp payload fields.
func (a *AMP) String() string {
return fmt.Sprintf("root_share=%x set_id=%x child_index=%d",
a.rootShare, a.setID, a.childIndex)
}