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https://github.com/lightningnetwork/lnd.git
synced 2025-09-08 05:08:13 +02:00
htlcswitch+refactor: continue modularising extractTLVPayload
We further break up the extracTLVPayload into more modular pieces. The pieces are structured in such a way as to prepare for extracTLVPayload being called in a recursive manner from within `deriveBlindedRouteForwardingInfo` when we add the logic for handling dummy hops in a later commit. With this refactor, we completey remove the BlindingKit's DecryptAndValidateFwdInfo method.
This commit is contained in:
Elle Mouton
@@ -202,20 +202,135 @@ func extractTLVPayload(r *sphinxHopIterator) (*Payload, RouteRole, error) {
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return payload, routeRole, nil
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}
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// If we had an encrypted data payload present, pull out our forwarding
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// info from the blob.
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fwdInfo, err := r.blindingKit.DecryptAndValidateFwdInfo(
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payload, isFinal,
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return parseAndValidateRecipientData(r, payload, isFinal, routeRole)
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}
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// parseAndValidateRecipientData decrypts the payload from the recipient and
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// then continues handling and validation based on if we are a forwarding node
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// in this blinded path or the final destination node.
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func parseAndValidateRecipientData(r *sphinxHopIterator, payload *Payload,
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isFinal bool, routeRole RouteRole) (*Payload, RouteRole, error) {
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// Decrypt and validate the blinded route data
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routeData, blindingPoint, err := decryptAndValidateBlindedRouteData(
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r, payload,
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)
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if err != nil {
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return nil, routeRole, err
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}
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payload.FwdInfo = *fwdInfo
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// Exit early if this onion is for the exit hop of the route since
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// route blinding receives are not yet supported.
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if isFinal {
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return nil, routeRole, fmt.Errorf("being the final hop in a " +
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"blinded path is not yet supported")
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}
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// Else, we are a forwarding node in this blinded path.
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return deriveBlindedRouteForwardingInfo(
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r, routeData, payload, routeRole, blindingPoint,
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)
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}
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// deriveBlindedRouteForwardingInfo uses the parsed BlindedRouteData from the
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// recipient to derive the ForwardingInfo for the payment.
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func deriveBlindedRouteForwardingInfo(r *sphinxHopIterator,
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routeData *record.BlindedRouteData, payload *Payload,
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routeRole RouteRole, blindingPoint *btcec.PublicKey) (*Payload,
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RouteRole, error) {
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relayInfo, err := routeData.RelayInfo.UnwrapOrErr(
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fmt.Errorf("relay info not set for non-final blinded hop"),
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)
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if err != nil {
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return nil, routeRole, err
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}
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nextSCID, err := routeData.ShortChannelID.UnwrapOrErr(
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fmt.Errorf("next SCID not set for non-final blinded hop"),
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)
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if err != nil {
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return nil, routeRole, err
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}
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fwdAmt, err := calculateForwardingAmount(
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r.blindingKit.IncomingAmount, relayInfo.Val.BaseFee,
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relayInfo.Val.FeeRate,
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)
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if err != nil {
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return nil, routeRole, err
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}
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nextEph, err := routeData.NextBlindingOverride.UnwrapOrFuncErr(
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func() (tlv.RecordT[tlv.TlvType8, *btcec.PublicKey], error) {
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next, err := r.blindingKit.Processor.NextEphemeral(
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blindingPoint,
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)
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if err != nil {
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return routeData.NextBlindingOverride.Zero(),
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err
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}
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return tlv.NewPrimitiveRecord[tlv.TlvType8](next), nil
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})
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if err != nil {
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return nil, routeRole, err
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}
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payload.FwdInfo = ForwardingInfo{
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NextHop: nextSCID.Val,
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AmountToForward: fwdAmt,
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OutgoingCTLV: r.blindingKit.IncomingCltv - uint32(
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relayInfo.Val.CltvExpiryDelta,
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),
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// Remap from blinding override type to blinding point type.
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NextBlinding: tlv.SomeRecordT(
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tlv.NewPrimitiveRecord[lnwire.BlindingPointTlvType](
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nextEph.Val,
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),
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),
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}
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return payload, routeRole, nil
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}
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// decryptAndValidateBlindedRouteData decrypts the encrypted payload from the
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// payment recipient using a blinding key. The incoming HTLC amount and CLTV
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// values are then verified against the policy values from the recipient.
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func decryptAndValidateBlindedRouteData(r *sphinxHopIterator,
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payload *Payload) (*record.BlindedRouteData, *btcec.PublicKey, error) {
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blindingPoint, err := r.blindingKit.getBlindingPoint(
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payload.blindingPoint,
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)
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if err != nil {
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return nil, nil, err
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}
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decrypted, err := r.blindingKit.Processor.DecryptBlindedHopData(
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blindingPoint, payload.encryptedData,
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)
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if err != nil {
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return nil, nil, fmt.Errorf("decrypt blinded data: %w", err)
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}
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buf := bytes.NewBuffer(decrypted)
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routeData, err := record.DecodeBlindedRouteData(buf)
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if err != nil {
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return nil, nil, fmt.Errorf("%w: %w", ErrDecodeFailed, err)
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}
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err = ValidateBlindedRouteData(
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routeData, r.blindingKit.IncomingAmount,
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r.blindingKit.IncomingCltv,
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)
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if err != nil {
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return nil, nil, err
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}
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return routeData, blindingPoint, nil
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}
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// parseAndValidateSenderPayload parses the payload bytes received from the
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// onion constructor (the sender) and validates that various fields have been
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// set. It also uses the presence of a blinding key in either the
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@@ -367,110 +482,6 @@ func (b *BlindingKit) getBlindingPoint(payloadBlinding *btcec.PublicKey) (
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}
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}
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// DecryptAndValidateFwdInfo performs all operations required to decrypt and
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// validate a blinded route.
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func (b *BlindingKit) DecryptAndValidateFwdInfo(payload *Payload,
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isFinalHop bool) (*ForwardingInfo, error) {
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// We expect this function to be called when we have encrypted data
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// present, and expect validation to already have ensured that a
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// blinding key is set either in the payload or the
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// update_add_htlc message.
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blindingPoint, err := b.getBlindingPoint(payload.blindingPoint)
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if err != nil {
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return nil, err
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}
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decrypted, err := b.Processor.DecryptBlindedHopData(
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blindingPoint, payload.encryptedData,
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)
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if err != nil {
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return nil, fmt.Errorf("decrypt blinded "+
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"data: %w", err)
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}
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buf := bytes.NewBuffer(decrypted)
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routeData, err := record.DecodeBlindedRouteData(buf)
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if err != nil {
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return nil, fmt.Errorf("%w: %w",
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ErrDecodeFailed, err)
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}
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// Validate the data in the blinded route against our incoming htlc's
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// information.
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if err := ValidateBlindedRouteData(
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routeData, b.IncomingAmount, b.IncomingCltv,
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); err != nil {
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return nil, err
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}
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// Exit early if this onion is for the exit hop of the route since
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// route blinding receives are not yet supported.
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if isFinalHop {
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return nil, fmt.Errorf("being the final hop in a blinded " +
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"path is not yet supported")
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}
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// At this point, we know we are a forwarding node for this onion
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// and so we expect the relay info and next SCID fields to be set.
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relayInfo, err := routeData.RelayInfo.UnwrapOrErr(
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fmt.Errorf("relay info not set for non-final blinded hop"),
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)
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if err != nil {
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return nil, err
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}
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nextSCID, err := routeData.ShortChannelID.UnwrapOrErr(
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fmt.Errorf("next SCID not set for non-final blinded hop"),
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)
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if err != nil {
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return nil, err
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}
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fwdAmt, err := calculateForwardingAmount(
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b.IncomingAmount, relayInfo.Val.BaseFee, relayInfo.Val.FeeRate,
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)
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if err != nil {
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return nil, err
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}
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// If we have an override for the blinding point for the next node,
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// we'll just use it without tweaking (the sender intended to switch
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// out directly for this blinding point). Otherwise, we'll tweak our
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// blinding point to get the next ephemeral key.
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nextEph, err := routeData.NextBlindingOverride.UnwrapOrFuncErr(
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func() (tlv.RecordT[tlv.TlvType8,
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*btcec.PublicKey], error) {
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next, err := b.Processor.NextEphemeral(blindingPoint)
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if err != nil {
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// Return a zero record because we expect the
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// error to be checked.
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return routeData.NextBlindingOverride.Zero(),
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err
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}
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return tlv.NewPrimitiveRecord[tlv.TlvType8](next), nil
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},
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)
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if err != nil {
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return nil, err
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}
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return &ForwardingInfo{
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NextHop: nextSCID.Val,
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AmountToForward: fwdAmt,
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OutgoingCTLV: b.IncomingCltv - uint32(
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relayInfo.Val.CltvExpiryDelta,
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),
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// Remap from blinding override type to blinding point type.
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NextBlinding: tlv.SomeRecordT(
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tlv.NewPrimitiveRecord[lnwire.BlindingPointTlvType](
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nextEph.Val),
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),
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}, nil
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}
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// calculateForwardingAmount calculates the amount to forward for a blinded
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// hop based on the incoming amount and forwarding parameters.
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//
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@@ -177,11 +177,11 @@ func (m *mockProcessor) NextEphemeral(*btcec.PublicKey) (*btcec.PublicKey,
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return nil, nil
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}
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// TestDecryptAndValidateFwdInfo tests deriving forwarding info using a
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// TestParseAndValidateRecipientData tests deriving forwarding info using a
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// blinding kit. This test does not cover assertions on the calculations of
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// forwarding information, because this is covered in a test dedicated to those
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// calculations.
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func TestDecryptAndValidateFwdInfo(t *testing.T) {
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func TestParseAndValidateRecipientData(t *testing.T) {
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t.Parallel()
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// Encode valid blinding data that we'll fake decrypting for our test.
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@@ -282,11 +282,15 @@ func TestDecryptAndValidateFwdInfo(t *testing.T) {
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tlv.NewPrimitiveRecord[lnwire.BlindingPointTlvType](testCase.updateAddBlinding),
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)
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}
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_, err := kit.DecryptAndValidateFwdInfo(
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&Payload{
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iterator := &sphinxHopIterator{
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blindingKit: kit,
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}
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_, _, err = parseAndValidateRecipientData(
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iterator, &Payload{
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encryptedData: testCase.data,
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blindingPoint: testCase.payloadBlinding,
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}, false,
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}, false, RouteRoleCleartext,
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)
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require.ErrorIs(t, err, testCase.expectedErr)
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})
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