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htlcswitch/iterator: use batch API for sphinx router

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This commit is contained in:
Conner Fromknecht 2018-01-16 00:36:14 -08:00
parent fcf08382f7
commit f075905d6c
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GPG Key ID: 39DE78FBE6ACB0EF
1 changed files with 209 additions and 24 deletions
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233
htlcswitch/iterator.go
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@ -40,6 +40,10 @@ var (
// exitHop is a special "hop" which denotes that an incoming HTLC is
// meant to pay finally to the receiving node.
exitHop lnwire.ShortChannelID
// sourceHop is a sentinel value denoting that an incoming HTLC is
// initiated by our own switch.
sourceHop lnwire.ShortChannelID
)
// ForwardingInfo contains all the information that is necessary to forward and
@ -85,14 +89,20 @@ type HopIterator interface {
// EncodeNextHop encodes the onion packet destined for the next hop
// into the passed io.Writer.
EncodeNextHop(w io.Writer) error
// ExtractErrorEncrypter returns the ErrorEncrypter needed for this hop,
// along with a failure code to signal if the decoding was successful.
ExtractErrorEncrypter(ErrorEncrypterExtracter) (ErrorEncrypter,
lnwire.FailCode)
}
// sphinxHopIterator is the Sphinx implementation of hop iterator which uses
// onion routing to encode the payment route in such a way so that node might
// see only the next hop in the route..
type sphinxHopIterator struct {
// nextPacket is the decoded onion packet for the _next_ hop.
nextPacket *sphinx.OnionPacket
// ogPacket is the original packet from which the processed packet is
// derived.
ogPacket *sphinx.OnionPacket
// processedPacket is the outcome of processing an onion packet. It
// includes the information required to properly forward the packet to
@ -100,6 +110,17 @@ type sphinxHopIterator struct {
processedPacket *sphinx.ProcessedPacket
}
// makeSphinxHopIterator converts a processed packet returned from a sphinx
// router and converts it into an hop iterator for usage in the link.
func makeSphinxHopIterator(ogPacket *sphinx.OnionPacket,
packet *sphinx.ProcessedPacket) *sphinxHopIterator {
return &sphinxHopIterator{
ogPacket: ogPacket,
processedPacket: packet,
}
}
// A compile time check to ensure sphinxHopIterator implements the HopIterator
// interface.
var _ HopIterator = (*sphinxHopIterator)(nil)
@ -108,7 +129,7 @@ var _ HopIterator = (*sphinxHopIterator)(nil)
//
// NOTE: Part of the HopIterator interface.
func (r *sphinxHopIterator) EncodeNextHop(w io.Writer) error {
return r.nextPacket.Encode(w)
return r.processedPacket.NextPacket.Encode(w)
}
// ForwardingInstructions returns the set of fields that detail exactly _how_
@ -137,6 +158,18 @@ func (r *sphinxHopIterator) ForwardingInstructions() ForwardingInfo {
}
}
// ExtractErrorEncrypter decodes and returns the ErrorEncrypter for this hop,
// along with a failure code to signal if the decoding was successful. The
// ErrorEncrypter is used to encrypt errors back to the sender in the event that
// a payment fails.
//
// NOTE: Part of the HopIterator interface.
func (r *sphinxHopIterator) ExtractErrorEncrypter(
extracter ErrorEncrypterExtracter) (ErrorEncrypter, lnwire.FailCode) {
return extracter(r.ogPacket)
}
// OnionProcessor is responsible for keeping all sphinx dependent parts inside
// and expose only decoding function. With such approach we give freedom for
// subsystems which wants to decode sphinx path to not be dependable from
@ -155,11 +188,22 @@ func NewOnionProcessor(router *sphinx.Router) *OnionProcessor {
return &OnionProcessor{router}
}
// Start spins up the onion processor's sphinx router.
func (p *OnionProcessor) Start() error {
return p.router.Start()
}
// Stop shutsdown the onion processor's sphinx router.
func (p *OnionProcessor) Stop() error {
p.router.Stop()
return nil
}
// DecodeHopIterator attempts to decode a valid sphinx packet from the passed io.Reader
// instance using the rHash as the associated data when checking the relevant
// MACs during the decoding process.
func (p *OnionProcessor) DecodeHopIterator(r io.Reader, rHash []byte) (HopIterator,
lnwire.FailCode) {
func (p *OnionProcessor) DecodeHopIterator(r io.Reader, rHash []byte,
incomingCltv uint32) (HopIterator, lnwire.FailCode) {
onionPkt := &sphinx.OnionPacket{}
if err := onionPkt.Decode(r); err != nil {
@ -179,7 +223,9 @@ func (p *OnionProcessor) DecodeHopIterator(r io.Reader, rHash []byte) (HopIterat
// associated data in order to thwart attempts a replay attacks. In the
// case of a replay, an attacker is *forced* to use the same payment
// hash twice, thereby losing their money entirely.
sphinxPacket, err := p.router.ProcessOnionPacket(onionPkt, rHash)
sphinxPacket, err := p.router.ProcessOnionPacket(
onionPkt, rHash, incomingCltv,
)
if err != nil {
switch err {
case sphinx.ErrInvalidOnionVersion:
@ -194,10 +240,160 @@ func (p *OnionProcessor) DecodeHopIterator(r io.Reader, rHash []byte) (HopIterat
}
}
return &sphinxHopIterator{
nextPacket: sphinxPacket.NextPacket,
processedPacket: sphinxPacket,
}, lnwire.CodeNone
return makeSphinxHopIterator(onionPkt, sphinxPacket), lnwire.CodeNone
}
// DecodeHopIteratorRequest encapsulates all date necessary to process an onion
// packet, perform sphinx replay detection, and schedule the entry for garbage
// collection.
type DecodeHopIteratorRequest struct {
OnionReader io.Reader
RHash []byte
IncomingCltv uint32
}
// DecodeHopIteratorResponse encapsulates the outcome of a batched sphinx onion
// processing.
type DecodeHopIteratorResponse struct {
HopIterator HopIterator
FailCode lnwire.FailCode
}
// Result returns the (HopIterator, lnwire.FailCode) tuple, which should
// correspond to the index of a particular DecodeHopIteratorRequest.
//
// NOTE: The HopIterator should be considered invalid if the fail code is
// anything but lnwire.CodeNone.
func (r *DecodeHopIteratorResponse) Result() (HopIterator, lnwire.FailCode) {
return r.HopIterator, r.FailCode
}
// DecodeHopIterators performs batched decoding and validation of incoming
// sphinx packets. For the same `id`, this method will return the same iterators
// and failcodes upon subsequent invocations.
//
// NOTE: In order for the responses to be valid, the caller must guarantee that
// the presented readers and rhashes *NEVER* deviate across invocations for the
// same id.
func (p *OnionProcessor) DecodeHopIterators(id []byte,
reqs []DecodeHopIteratorRequest) ([]DecodeHopIteratorResponse, error) {
var (
batchSize = len(reqs)
onionPkts = make([]sphinx.OnionPacket, batchSize)
resps = make([]DecodeHopIteratorResponse, batchSize)
)
tx := p.router.BeginTxn(id, batchSize)
for i, req := range reqs {
onionPkt := &onionPkts[i]
resp := &resps[i]
err := onionPkt.Decode(req.OnionReader)
switch err {
case nil:
// success
case sphinx.ErrInvalidOnionVersion:
resp.FailCode = lnwire.CodeInvalidOnionVersion
continue
case sphinx.ErrInvalidOnionKey:
resp.FailCode = lnwire.CodeInvalidOnionKey
continue
default:
log.Errorf("unable to decode onion packet: %v", err)
resp.FailCode = lnwire.CodeInvalidOnionKey
continue
}
err = tx.ProcessOnionPacket(
uint16(i), onionPkt, req.RHash, req.IncomingCltv,
)
switch err {
case nil:
// success
case sphinx.ErrInvalidOnionVersion:
resp.FailCode = lnwire.CodeInvalidOnionVersion
continue
case sphinx.ErrInvalidOnionHMAC:
resp.FailCode = lnwire.CodeInvalidOnionHmac
continue
case sphinx.ErrInvalidOnionKey:
resp.FailCode = lnwire.CodeInvalidOnionKey
continue
default:
log.Errorf("unable to process onion packet: %v", err)
resp.FailCode = lnwire.CodeInvalidOnionKey
continue
}
}
// With that batch created, we will now attempt to write the shared
// secrets to disk. This operation will returns the set of indices that
// were detected as replays, and the computed sphinx packets for all
// indices that did not fail the above loop. Only indices that are not
// in the replay set should be considered valid, as they are
// opportunistically computed.
packets, replays, err := tx.Commit()
if err != nil {
log.Errorf("unable to process onion packet batch %x: %v",
id, err)
// If we failed to commit the batch to the secret share log, we
// will mark all not-yet-failed channels with a temporary
// channel failure and exit since we cannot proceed.
for i := range resps {
resp := &resps[i]
// Skip any indexes that already failed onion decoding.
if resp.FailCode != lnwire.CodeNone {
continue
}
log.Errorf("unable to process onion packet %x-%v",
id, i)
resp.FailCode = lnwire.CodeTemporaryChannelFailure
}
// TODO(conner): return real errors to caller so link can fail?
return resps, err
}
// Otherwise, the commit was successful. Now we will post process any
// remaining packets, additionally failing any that were included in the
// replay set.
for i := range resps {
resp := &resps[i]
// Skip any indexes that already failed onion decoding.
if resp.FailCode != lnwire.CodeNone {
continue
}
// If this index is contained in the replay set, mark it with a
// temporary channel failure error code. We infer that the
// offending error was due to a replayed packet because this
// index was found in the replay set.
if replays.Contains(uint16(i)) {
log.Errorf("unable to process onion packet: %v",
sphinx.ErrReplayedPacket)
resp.FailCode = lnwire.CodeTemporaryChannelFailure
continue
}
// Finally, construct a hop iterator from our processed sphinx
// packet, simultaneously caching the original onion packet.
resp.HopIterator = makeSphinxHopIterator(&onionPkts[i], &packets[i])
}
return resps, nil
}
// ExtractErrorEncrypter takes an io.Reader which should contain the onion
@ -205,20 +401,8 @@ func (p *OnionProcessor) DecodeHopIterator(r io.Reader, rHash []byte) (HopIterat
// ErrorEncrypter instance using the derived shared secret. In the case that en
// error occurs, a lnwire failure code detailing the parsing failure will be
// returned.
func (p *OnionProcessor) ExtractErrorEncrypter(r io.Reader) (ErrorEncrypter, lnwire.FailCode) {
onionPkt := &sphinx.OnionPacket{}
if err := onionPkt.Decode(r); err != nil {
switch err {
case sphinx.ErrInvalidOnionVersion:
return nil, lnwire.CodeInvalidOnionVersion
case sphinx.ErrInvalidOnionKey:
return nil, lnwire.CodeInvalidOnionKey
default:
log.Errorf("unable to decode onion packet: %v", err)
return nil, lnwire.CodeInvalidOnionKey
}
}
func (p *OnionProcessor) ExtractErrorEncrypter(onionPkt *sphinx.OnionPacket) (
ErrorEncrypter, lnwire.FailCode) {
onionObfuscator, err := sphinx.NewOnionErrorEncrypter(p.router,
onionPkt.EphemeralKey)
@ -238,5 +422,6 @@ func (p *OnionProcessor) ExtractErrorEncrypter(r io.Reader) (ErrorEncrypter, lnw
return &SphinxErrorEncrypter{
OnionErrorEncrypter: onionObfuscator,
ogPacket: onionPkt,
}, lnwire.CodeNone
}